microsoft word lankika lankika et al.,/journal of tropical forestry and environment vol. 2, no. 02 (2012) 37-42 37 species composition of odonate fauna in meegahawatta, a wetland area in hanwella, sri lanka m.d.h. lankika* 1 , m.m.s.c. karunaratne 1 and k. conniff 2 1 department of zoology, university of sri jayewardenepura, nugegoda, sri lanka 2 k. conniff, c/o icimod, kathmandu, nepal date received: 12-01-2012 date accepted: 21-06-2012 abstract approximately 120 species of odonata (zygoptera and anisoptera) have been recorded in sri lanka to date. there are many gaps in our knowledge of odonata taxonomy and distribution. the present study, therefore, was carried out to investigate adult odonata species present in meegahawatta area (1000m 2 ) in hanwella. the study was carried out using two fixed quadrats (20m x 10m) randomly established in two selected sites. total number of individuals belonging to each species was counted fortnightly by using binoculars. a total of 27 species, 11 zygoptera and 16 anisoptera representing eight families were recorded. this comprised of three endemic zygopteran species (libellago adami, pseudagrion rubiceps ceylonicum and prodasineura sita) and three endemic anisopteran species (epopthalmia vittata cyanocephala, cyclogomphus gynostylus and macrogomphus lankanensis). among those identified was one recently discovered and yet un-described archibasis species. of the three endemic anisopteran species recorded, c. gynostylus and m. lankanensis are listed as vulnerable species in the iucn redlist of 2010. although the zygopterans showed higher diversity index and evenness index (h’= 1.99, e= 0.83) than the anisopterans (h’=1.96, e= 0.32), their richness index (r=1.67) was less than that of the anisopterans (r= 2.49). the most common zygopteran species recorded was pseudagrion malabaricum whereas neurothemis tulia tulia was the most common anisopteran species. key words: odonate fauna, anisoptera, zygoptera, species composition, meegahawatta wetland area 1. introduction the order odonata (dragonflies and damselflies) contains about 6000 described species of medium to very large insects. the highest species number is known from the oriental region which has more than 1,000 species (nesemann et al., 2011). it is an insect order of much interest to naturalists as well as to scientists focusing on studies in ecology or biodiversity. although generally considered to have little economic significance, adults and larvae of all odonate species are key predators among insects recorded frequently in aquatic ecosystems (corbet, 1999). although odonates can occupy nearly almost all kinds of habitats, aquatic habitats with high heterogeneity of vegetation are believed to be ideal for them (wahizatul-afzan et al., 2006), thus wetlands indicating high diversity of odonate species. in several countries, these insects are being used as an important ecological tool to assess the quality of aquatic ecosystems such as streams, rivers, and lakes because of their high sensitivity to human disturbances (fulan et al., 2010). *correspondence: harshi87@hotmail.com tel: +94-723234407 issn 2235-9370 print / issn 2235-9362 online ©2012 university of sri jayewardenepura lankika et al.,/journal of tropical forestry and environment vol. 2, no. 02 (2012) 37-42 38 even though the odonate fauna all over the world is well-known (arulprakash and gunathilagaraj, 2010), there are many gaps in the knowledge of sri lankan odonate fauna (bedjanic, 2004). currently, 120 odonate species have been identified in sri lanka of which 55 are zygopterans belonging to 8 families and 65 are anisopterans belonging to 4 families (bedjanic, 2006; iucn, 2007). this contains 57 endemic, 13 critically endangered, 5 endangered and 2 vulnerable species (iucn, 2010) making the odonate fauna in sri lanka a very threatened insect group (bedjanic, 2004). the present study, therefore, was carried out in order to identify the odonata species present in meegahawatta wetland area as it is a locality which provides suitable habitats for a large number of fauna including odonates. the knowledge gained thus would support the sri lankan odonata checklist and is also vital for the conservation of these insects. moreover, information on distribution and species composition is essential for further studies of biogeography and habitat usage of these insects. 2. materials and methods 2.1. study area the present study was conducted in a forested wetland area in hanwella known as meegahawatta wetland (1000m 2 ). it is situated within the low country wet zone and has a tropical monsoon climate. two sites were selected as the study area (figure1) and the first site (20m x 10m) comprised of two shallow water filled bogs (2m x 0.5m) along the entrance of the wetland area. figure 1: study area in meegahawatta wetland, hanwella. the box above represents sampling site 1and the box below represents sampling site 2 lankika et al.,/journal of tropical forestry and environment vol. 2, no. 02 (2012) 37-42 39 the adjacent land area with lush vegetation, mainly consisting of grasses and climbers such as cyperus pilosus, ischaemum timorense, ipomoea pes-caprae and ipomoea mauritiana is seasonally flooded. the two bogs consist of such aquatic plants as cyperus sp., nymphoides parriflora and utricularia aurea. the water surface is partially covered by shrubs and trees such as syzygium caryophyllatum and cerbera odollam, and hence is not completely exposed to sunlight. there is a permanent small stream with clear running water at the second site (20m x 10m) of the study area and a dense vegetation cover with similar grasses, climbers and trees found at the first site. the canopy is made of different types of bamboo species which somewhat covered the water surface. except for utricularia aurea no other aquatic plants are found in the water way. 2.2. sampling method this study was carried out from january to may 2011. the total number of odonata species observed inside the sampling area was recorded throughout this period. the two entire sampling sites were thoroughly scanned once in two weeks with the use of a pair of binoculars. both sampling sites were visited on the same day and data were collected between 9.00 – 11.00 am. all the individuals observed and recorded were identified to the species level with reference to taxonomic keys (de fonseka, 2000; de silva wijeratne et al., 2003). 2.3. data analysis the species diversity (h’) for the study area was calculated using the shannon wiener diversity index. h’ = ∑ pi ln pi…………... (1) where, pi= ni/n, ni= total number of individuals belonging to i th species, n= total number of individuals belonging to the sampled population species richness index was calculated using margalef’s richness index (r). r = s -1/ln (n)………….. (2) where, s= total number of species species evenness was calculated using evenness index (e). e = h’/ln (s)………….. (3) 3. results and discussion a total of 27 odonate species were identified from meegahawatta wetland area during the study period. the odonate species recorded comprised of 11 zygoptera species belonging to 4 families (chlorocyphidae, coenagrionidae, platycnemididae and protoneuridae) and 16 anisoptera species belonging to 4 families (gomphidae, aeshnidae, libellulidae and corduliidae (table 1). the most common species recorded during the study period (figure 2) were the zygopteran pseudagrion malabaricum (13%) and the anisopteran neurothemis tulia tulia (20%). on the other hand, the least common species found were ischnura aurora, cyclogomphus gynostylus, macrogomphus lankanensis, orthetrum luzonicum, rhodothermis rufa, epopthalmia vittata cyanocephala. according to the calculated biological indices (figure 3), species diversity and evenness in zygopterans (1.99, 0.83) were higher than those of the anisopterans (1.96, 0.32). however, richness index was higher in anisopterans (2.49) than in zygopterans (1.67). lankika et al.,/journal of tropical forestry and environment vol. 2, no. 02 (2012) 37-42 40 table1: odonate species composition at meegahawatta wetland area in hanwella, sri lanka during the period of january to may 2011 suborder family scientific name common name zygoptera chlorocyphidae libellago adami e (fraser, 1939) adam’s gem coenagrionidae agriocnemis pygmaea pygmaea (rambur, 1842) wandering wisp ceriagrion cerinorubellum (brauer, 1866) painted waxtail ceriagrion coromandelianum (fabricius, 1798) yellow waxtail pseudagrion malabaricum fraser, 1924 malabar sprite pseudagrion rubriceps ceylonicum e (kirby, 1891) sri lanka orangefaced sprite ischnura aurora aurora (brauer, 1865) dawn bluetail onychargia atrocyana (selys, 1865) marsh dancer platycnemididae copera marginipes (rambur, 1842) yellow featherlegs protoneuridae prodasineura sita e (kirby, 1893) stripe-headed treadtail archibasis sp (nov) anisoptera gomphidae cyclogomphus gynostylus v,e (fraser, 1925) transvestite clubtail macrogomphus lankanensis v,e (fraser, 1933) sri lanka forktail ictinogomphus rapax (rambur, 1842) rapacious flangetail aeshnidae gynacantha dravida (fraser, 1936) indian duskhawker libellulidae brachydiplax sobrina (rambur, 1842) sombre liutenant orthetrum luzonicum (brauer, 1868) marsh skimmer orthetrum sabina sabina (drury, 1770) green skimmer acisoma panorpoides panorpoides (rambur, 1842) asian pintail brachythemis contaminata (fabricius, 1793) asian grounling neurothemis tulia tulia (drury, 1773) pied parasol rhodothemis rufa (rambur, 1842) spine-legged redbolt trithemis aurora (burmeister, 1839) crimson dropwing rhyothemis trianglularis (kirby, 1889) blue-based flutterer rhyothemis variegata variegata (linnaeus, 1763) variable flutterer tholymis tillarga (fabricius, 1798) foggy-winged twister corduliidae epophthalmia vittata cyanocephala e (hagen, 1866) blue-eyed cruiser v =vulnerable, e = endemic, nov= novel the 27 odonate species recorded in meegahawatta wetland area during the study period comprised of 22.5% of the total sri lankan odonate fauna. this included six endemic species (table 1) comprising three zygopteran species (libellago adami, pseudagrion rubiceps ceylonicum and prodasineura sita) and three anisopteran species (epopthalmia vittata cyanocephala, cyclogomphus gynostylus and macrogomphus lankanensis). of the three endemic anisopteran species recorded, c. gynostylus and m. lankanensis are listed as vulnerable species in the iucn redlist of 2010. also, both of these species have been stated as a taxonomically isolated group by bedjanic (2004). it is of great significance that the two vulnerable species recorded in the study area are the same and the only two lankika et al.,/journal of tropical forestry and environment vol. 2, no. 02 (2012) 37-42 41 vulnerable species recorded in the checklist of sri lanka (iucn, 2007). furthermore, among the identified species during the study period was one quite recently discovered and yet un-described archibasis species. bedjanic in 2004 also referred to a novel archibasis sp. but it is not described as yet. this merits a great need for further studies to describe the exact species. figure 2: odonate species composition in meegahawatta wetland area during the study period figure 3: species diversity, richness and evenness of odonates recorded in meegahawatta wetland area. h’-shannon wiener diversity index, r-margalef richness index, e – evenness index lankika et al.,/journal of tropical forestry and environment vol. 2, no. 02 (2012) 37-42 42 although the odonate fauna in sri lanka is ecologically important, little research has been conducted so far on their distribution, abundance, biology and habitats. hence, the data acquired in this study should, ideally be, put in an odonatological database to generate distribution maps and also to determine their conservation status. lastly, the presence of a relatively high number of odonate species consisting six endemic species that include two vulnerable species within this relatively small wetland area suggests urgent need to employ much needed conservation measures to safeguard this vital ecosystem. references arulprakash, r and k, gunathilagaraj. 2010. abundance and diversity of odonata in temporary water bodies of coimbotore and sahlem districts in tamil nadu. journal of threatened taxa.2 (8):1099-1102. bedjanic, m. 2004. odonata fauna of sri lanka: research state and threat status. international journal of odonatology.7 (2): 279-294. bedjanic, m. 2006. current status of taxonomy, research and conservation of dragonfly fauna (insect: odonata) of sri lanka. the fauna of sri lanka: status of taxonomy, research and conservation. sri lanka government of sri lanka, colombo.1:2030. corbet, p. s. 1999. dragon flies: behavior and ecology. new york, usa: cornell university press. 829 pp. de fonseka.t. 2000. dragonflies of sri lanka. wild life heritage trust, colombo. de silva wijeratne, g., m. bedjanic and k. conniff, 2003. dragonflies of sri lanka. gegan’s photo booklet.jetwing research initiative,colombo. fulan, j. a., r. raimundo, d. figueiredo and m. correia, 20 �10. abundance and diversity of dragon flies four years after the construction of a reservoir. limnetica, 29 (2): 279-286. iucn sri lanka., 2010. a comparison of the conservation and legal status of the fauna and flora of sri lanka. iucn sri lanka, colombo. iucn sri lanka, 2007. the 2007 red list of threatened fauna and flora of sri lanka. the world conservation union and ministry of environment and natural resources, colombo, sri lanka. nesemann, h., r. d. t. shah and d. n. shah, 2011. key to the larval stages of common odonata of hindu kush himalaya, with short notes on habitats and ecology journal of threatened taxa 3(9): 2045–2060. wahizatul-afzan, a. j. julia and a. amirrudin, 2006. diversity and distribution of dragonflies (insecta: odonata) in sekayu recreational forest, terengganu. journal of sustainability, science and management. 1 (2): 97106. 76 *correspondence: upuls@sjp.ac.lk tel: +94714450339 © university of sri jayewardenepura prediction of the early growth of plantation grown g. walla p.g.t. dilrukshi1, s.m.c.u.p. subasinghe1*, a.m.w.k. senevirathne2, n.m.c. nayanakantha3 1centre for forestry and environment, department of forestry and environmental science, university of sri jayewardenepura, nugegoda, sri lanka 2department of export agriculture, uva wellassa university, badulla, sri lanka 3department of biosystems technology, uva wellassa university, badulla, sri lanka date received: 15-04-2021 date accepted: 29-06-2021 abstract certain tree species of thymalaeaceae family produce highly fragrant, valuable resin called agarwood inside the stems, branches and roots due to a defence mechanism to protect internal tissue damage from invading microorganisms. gyrinops walla is the only native tree species bearing the agarwood resin production ability which is growing in the low and mid elevations of wet climates of sri lanka. after some years of discovering the ability to produce agarwood resins in of g. walla, private sector investors planned to establish small and medium scale plantations using this species. however, information on g. walla growth rates under plantations conditions were not available, which are essential for the effective management. therefore the present study aimed at constructing height and diameter prediction models for the early stages of g. walla plantations. for this purse, monthly measured height and diameter data of 40 plants of an even-aged g. walla plantation were used. several non-linear and 2nd and 3rd order polynomial models were initially tested, keeping age as the single explanatory variable. among them, the best performances were given by the 2nd order polynomial models for both height and diameter variables. both models had r2 over 99.0 and root mean square error and mean absolute difference less than 0.10, proving high accuracy. fitted line plots also did not indicate deviations of the residuals. though the models built in this study are recommended for predicting the early plantation growth of g. walla, future research should be conducted to validate them till the maturity of the trees. keywords: g. walla, polynomial regression, growth modelling, plantation, height, diameter 1. introduction agarwood is a highly valuable resin in incense and perfume markets of various parts of the world (okudera and ito, 2009; kakino et al., 2010; peng et al., 2015). it is produced by certain tree members of family thymalaeaceae as a defence mechanism to protect the internal tissue damage from external microorganisms (rogers, 2009; chen et al., 2011). agarwood is mainly sold in two forms in the market as black or brown colour chips and as extracted oils from the tissues. a good quality agarwood kilo of any form is sold for about usd 30,000.00. gyrinops walla, the only agarwood producing tree member of thymalaeaceae family naturally growing in sri lanka is commonly found in the homegardens and natural forests of the wet zone of the country (dassanayake and fosberg, 1981). this species does not have any timber value and its ability of producing agarwood was scientifically proven by subasinghe et al. (2012) and subasinghe and hettiarachchi (2013). they also found out for the first time that agarwood of g. walla has similar qualities to the agarwood available in the market which are produced from the other species of the same family growing in southeast asian countries (espinoza et al., 2014). due to the high value of agarwood produced in g. walla, private sector investors recently tend to cultivate this species in small and medium scale. this will create opportunity to obtain a considerable foreign income due to the high dilrukshi et al. /journal of tropical forestry and environment vol. 11 no. 1 (2021) 76-80 77 demand for raw agarwood and related products. information on seed germination and nursery establishment of g. walla have already been identified via some research (page and awarau, 2012) which are helpful for plantation establishment. however, no studies have yet been conducted on plantation establishment using this species and its growth rates which are essential to determine the time for inoculation and harvesting age. therefore, the present study aimed at building mathematical models to predict the height and diameter growth of g. walla during the early stages of plantation establishment. a growth model can be considered as an abstraction of reality, by which the key relationships of a selected biological mechanism are being conceptualised (vanclay, 2017). forest growth models therefore, provide platforms for forest managers to predict the growth, even without years of experience (vanclay, 1994, chaudhuri et al., 1995). thereby, growth models become powerful tools in quantification of tree variables which are helpful for the forest managers take effective decisions on their forests. however, model construction is a long term exercise because of the need of data measured at regular intervals to make proper forecasts of the tree growth via easily measureable variables. the idea of tree growth modelling is to provide a simple platform for the users for forecasting required variables without much efforts (adame et al., 2008). linear models are useful in this aspect though they may not be accurate with long-term prediction of biological variables, especially against time. while non-linear regression allows greater flexibility in formulating models to ensure sensible extrapolation, it does have some limitations. one problem is that, unlike linear regression, non-linear regression does not necessarily provide a unique best unbiased solution for a given set of variables (vanclay, 1994). 2. methodology 2.1 measurements a 2 ha gyrinops walla plantation established in 2017 in kalutara district of the wet zone of sri lanka was selected for taking necessary measurements. the distance between plants was 3m×3m comprising 1,111 plants per ha. height from the ground to the topmost growing position of the main stem and the diameter at 30 cm above the ground were measured using a calibrated pole and a calliper respectively at monthly intervals for four years. randomly selected 40 plants were used for taking both measurements. 2.2 building relationships the intention of the present study was to develop simple, but robust models for redacting height and diameter growth of g. walla at the early years of plantation establishment. therefore the model building was conducted using the general form given in equation 1. selection of the suitable candidate models were done based on the scatter distribution of height and diameter values with the age. then, logistic, michaelis-menten and second and third order polynomial models were fitted to the collected data to find the best fit. height and diameter growth=f(age) 2.3 determination of the quality of the models the quality of the models were determined quantitatively by coefficient of determination (r2), root mean square error (rmse), and mean absolute difference (mad) and qualitatively by the distribution of the fitted lines on raw data. rmse=√ (�̂�𝑖−𝑦𝑖) 2 𝑛 (1) (2) 78 mad= ∑|y î -y i | n where: n=number of data 𝑦𝑖=observed variable 𝑦�̂�=predicted variable 3. results out of the tested models 2nd order polynomial equations produced the best results as shown in table 1. therefore those models were selected for further testing with fitted line plots (figure 1-2). table 1: description of the resultant second order polynomial models. model r2 rmse mad height=0.9457+0.0050×age+0.0009×age2 99.76% 0.032 0.024 diameter=0.4112+0.0292×age+0.0023×age2 99.82% 0.084 0.071 the r2 values of both height and diameter models were above 99% and root mean square error and mean absolute difference values were lower than 0.1 proving high accuracy and low bias of the selected models (table 1). fitted lines and measured data were also closely arranged indicating a very low deviations of the residuals. figure 1. averaged measured height values and the fitted line. figure 2. averaged measured diameter values and the fitted line. 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 0 10 20 30 40 50 h e ig h t, m age, month 0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 0 10 20 30 40 50 d ia m e te r, c m age, month (3) dilrukshi et al. /journal of tropical forestry and environment vol. 11 no. 1 (2021) 76-80 79 4. discussion though aquilaria plantations were established in southeast asian region, modelling the growth of those species was even not frequently studied in the past. in 1996, hai and yahya developed a linear equation to predict height of a. malaccensis from diameter. however, some researchers attempted to model the quality of agarwood oil against different extraction methods, e.g. pornpunyapat et al., (2011). the main requirement of a successful model is its ability of maintaining a high accuracy in predicting the response variable. therefore, in modelling, it is a common practice to transform data into biologically accepted forms to minimise the prediction error (subasinghe and munasinghe, 2011, vanclay, 1994). however, it was not necessary for the present study because the modelling error of the constructed 2nd order polynomial models was negligible. though different non-linear modes were tested in this study, the best fit was obtained by second order polynomial equations. the main intention of model building for describing biological relationships is to establish simple, but robust relationships which is easy and accurate for the user (vanclay, 1994). some believe that, the behaviour of polynomial equations cannot be biologically explained because the same explanatory variable is entered into the equation with changing power value. however, many researchers, e.g. (brown, 1997) successfully used polynomial equations for tree growth prediction. therefore it is recommended to use the models developed in this study for the young stage of g. walla plantations to predict the height and diameter values against age. however, due to lack of data, the variation of the growth till the maturity of g. walla plantations were not available for this study. further, the use of the models built in this study cannot be recommended for extrapolating the growth till the maturity due to the differences of the biological growth of the trees with the age. therefore, it is recommended to continue similar research by collecting data till the maturity of g. walla trees so that the models built in this study can be further validated. references adame, p., hynynen, j., canellas, i. and del río, m., 2008. individual-tree diameter growth model for rebollo oak (quercus pyrenaica willd.) coppices. forest ecology and management, 255(3-4): 1011-1022. brown, s., 1997. estimating biomass and biomass change of tropical forests: a primer. fao forestry paper 134, food and agriculture organisation to the united nations, rome. chaudhuri, d., kurungara, v.k., sethuraj, m.r., 1995. estimation of biomass in hevea clones by regression method: relation between girth and biomass. indian journal of natural rubber research, 8(2):113-116. chen, h., yang, y., xue, j., wei, j., zhang, z., chen, h., 2011. comparison of compositions and antimicrobial activities of essential oils from chemically stimulated agarwood, wild agarwood and healthy aquilaria sinensis (lour.) gilg trees. molecules, 16:4884-4896. peng, c.s., osman, m.f., bahari, n., zakaria, r. and rahim, k.a., 2015. agarwood inducement technology: a method for producing oil grade agarwood in cultivated aquilaria malaccensis lamk. journal of agrobiotechnology, 6: 1-16. dassanayake, m.d., fosberg, f.r., 1981. flora of sri lanka. ibh publishing company, new delhi, india. espinoza, e.o., lancaster1, c.a., kreitals, n.m., hata, m., cody, r.b., blanchette, r.a., 2014. distinguishing wild from cultivated agarwood (aquilaria spp.) using direct analysis in real time and time of-flight mass spectrometry. rapid communication in mass spectrometry, 28:281289. hai, l.e., yahya, a.z., 1996. the growth performance of plantation grown aquilaria malaccensis in peninsular malaysia. journal of tropical forest science, 8(4):573-575. 80 kakino, m., tazawa, s., maruyama, h., tsuruma, k., araki, y., shimazawa, m. and hara, h., 2010. laxative effects of agarwood on low-fiber diet-induced constipation in rats. bmc complementary and alternative medicine, 10(1): 1-8. okudera y, ito m., 2009. production of agarwood fragrant constituents in aquilaria calli and cell suspension cultures. plant biotechnology, 26: 307-315. page, t. awarau, a., 2012. performance of agarwood (aquilaria crassna) seedling transplants improved by shade and fertiliser. forest ecology and management, 265: 258-269. pornpunyapat, j., chetpattananondh, p., tongurai, c., 2011. mathematical modelling for extraction of essential oil from aquilaria crassna by hydrodistillation and quality of agarwood oil. bangladesh journal of pharmacology, 6:18-24. rogers, z.s., 2009. a world checklist of thymelaeaceae (version 1). missouri botanical garden, st. louis, mo, usa. subasinghe, s.m.c.u.p., munasinghe, g.b., 2011. estimation of above ground tree biomass and carbon of pinus caribaea ( morelet ). journal of tropcial forestry and environment, 1(1): 5771. subasinghe, s.m.c.u.p. and hettiarachchi, d.s., 2013. agarwood resin production and resin quality of gyrinops walla gaertn. international journal of agriculture and science, 3: 357-362. subasinghe, s.m.c.u.p., hettiarachchi, d.s., rathnamalala, e., 2012. agarwood-type resin from gyrinops walla gaertn: a new discovery. journal of tropcial forestry and environment, 2(2): 43-48. vanclay, j.k., 1994. modelling forest growth and yield: applications to mixed tropical forests. cab international, uk. vanclay, j.k., 2017. robust models for smallholder forests. indian forester, 143(9): 852-855. dissanayake et al. /journal of tropical forestry and environment vol. 11 no. 1 (2021) 69-75 69 *correspondence: sandalidissanayake89@gmail.com tel: +94715277235 © university of sri jayewardenepura value additions on iron-oxide nanoparticles in laterite soils available in south-west sri lanka: development of effective filtering techniques n.u.s. dissanayake*, b. m. gunathilake, s. ranasinghe department of forestry and environmental science, faculty of applied sciences, university of sri jayewardenepura, nugegoda, sri lanka date received: 15-03-2021 date accepted: 22-06-2021 abstract environmental contamination by phosphate is on the rise with extensive and diffuse pollution. answering these badly behaved with serious technologies is very costly. soil has been commonly used in several wastewater treatment systems and showed to be an in effect substrate for phosphate removal and retention. using natural sorbent such as laterite could be a way out. the removal of phosphate from aqueous solutions was investigated by using raw laterite in this study. in the adsorption process, the effect of ph, contact time, concentration, adsorbent dosage and salt concentrations were taken into consideration and experiments were carried out in the batch experiment system. laterite proved to be an effective adsorbent and the removal efficiency remained around 90% of all cases. the optimal dosage was identified as 1g and the removal efficiency was more than 90%. study of the adsorption as a function of contact time showed that 3 hours was sufficient time for maximum removal of phosphate. acidic environments of ph values less than 5 facilitated the adsorption of phosphate and the removal efficiency decreased with increasing ph value of the solution. based on the obtained results from this study, raw laterite is effective in removing phosphate from aqueous solutions and is a cost effective alternative for commercially available adsorbents that are currently used to remove contaminants from drinking water. keywords: adsorption, phosphate, laterite, removal, efficiency 1. introduction phosphorus is an indispensable element for all life on earth that exists naturally as phosphate ion. phosphate is added to the environment natural due to decomposition of rocks and minerals, storm water runoff, agricultural runoff (johnson et al., 2007; donald et al., 2011), erosion and sedimentation, atmospheric deposition, direct input by animals. phosphate is also added due to anthropogenic activities such as discharge from wastewater treatment plants and permitted industries (mueller, 1995). out of the main sources of phosphate, municipal wastewater has a significant portion of phosphate than others (binder et al., 2009; egle et al., 2014). the natural background levels of total phosphorus are generally less than 0.03 mg/l. the natural levels of phosphate usually range from 0.005 to 0.05 mg/l in water and soil solutions generally contain 0.20 to 0.30 mg/l (daniel et al. 1998). many bodies of freshwater are currently experiencing increases of phosphorus from outside sources. the range from 0.025 0.1 mg/l stimulates the algal growth and levels greater than 0.1 mg/l accelerates the growth of algae that (brian, 2005). small additions of phosphorus can result in large changes in aquatic systems and deteriorate the water quality by changing physical, chemical and biological parameters of the water bodies (carneiro et al., 2014). too much phosphorus triggers vigorous growth of algae and larger aquatic plants, which can result in decreased levels of dissolved oxygen, a process called eutrophication. high levels of phosphorus can also lead to algae blooms that produce algal toxins which can be harmful to human & animal health and suffocates fish populations https://www.sciencedirect.com/topics/earth-and-planetary-sciences/diffuse-pollution https://www.sciencedirect.com/topics/earth-and-planetary-sciences/sorbent https://www.sciencedirect.com/topics/earth-and-planetary-sciences/laterite 70 (chislock et.al., 2013). the most visible effect of cultural eutrophication is the creation of dense blooms of toxic, and foul-smelling phytoplankton that reduces the clearness of water and harms water quality. algal blooms limit light penetration, reducing growth and causing die-offs of plants in littoral zones and complicates the process of water purification (tilman et al., 2001). in order to combat eutrophication like water issues of water reservoirs phosphate should be removed and maintain at its safe level. various technologies are used to remove phosphorus from wastewater, including: chemical precipitation, membrane separation, biological treatment, and adsorption (yeoman et al., 1988). but chemical and biological phosphorous treatments are the two main techniques that are used in removing phosphorus from domestic and industrial wastewater. furthermore, many variations and combinations have been used for the treatment processes. however, these methods of phosphate removal from drain liquids also have certain disadvantages, such as capital costs, operation and maintenance costs, coagulants generate as secondary pollution and complex usage. clay minerals have widely been used for removal of phosphate from wastewater. hamdi and srasra (2012) dealt with the removal of phosphate ions from aqueous solutions using kaolinitic and smectic clay minerals and synthetic zeolite as an adsorbent. as well as al-modified betonite samples were prepared and used for phosphorus removal from the various phosphate contains solutions (elsergany and shanableh, 2012). laterite is a common secondary clay mineral present in tropical countries under wet climate, that is rich in iron and aluminium predominantly with rusty-red color due to higher levels of iron oxides. laterite consist specific iron and aluminium bearing primary and secondary minerals such as kaolinite, goethite, hematite, gibbsite and quartz. it usually forms in hot and wet tropical and subtropical regions of sri lanka, where the climate is humid. laterite soil has a higher percentage of clay, higher cation exchange capacity with higher water retaining capacity. in general, laterite is soft and wet in nature (engelhardt, 2010). it has a strong affinity for sorption of inorganic and organic contaminants. hence, laterite has been revealed as an effective filter media for contaminated water. therefore, the scope of this study is to use laterite as a filter medium to remove phosphate in an aqueous solution. the main objectives are to explore an effective phosphate filtering system by laterite soil and to investigate the optimum characteristics of the material for associated sorption processes. 2. methodology 2.1 sample preparation laterite soil samples were collected from the western province of sri lanka by auger drilling method. collected soils were air-dried about 48 hours to remove the excess moisture content. air-dried soil was crushed to prepare powdered material (106 µm). 2.2 chemical experimentation the adsorption of phosphate into the laterite soil was carried out under different conditions. under room temperature and natural ph, the optimum adsorbent soil dosage, optimum phosphate concentration and optimum contact time were studied at the beginning. the ascorbic acid method (eaton et al., 2005) was followed for all the experiments and finally, the removal efficiency of the samples was measured using the uv spectrophotometer at 890 nm wavelength. readings were taken in triplicates to increase the accuracy. the absorbed amount of phosphate at the equilibrium was calculated by the equation 1. where c0 is the initial concentration of the phosphate (ppm), and ce is the equilibrium concentration of the phosphate (ppm). the removal efficiency was calculated according to equation 1. percentage removal efficiency= (c0-ce)×100 c0 where: (1) 71 c0=initial concentration of the phosphate (ppm) ce=equilibrium concentration of the phosphate (ppm) 2.3 determination of the optimum soil dosage a phosphate stock solution of 1000 ppm was prepared by dissolving kh2po4 in deionized water and needed solutions were prepared dilutions. initial phosphate concentration was prepared to 50 ppm and then 50.0 ml of the solution was added to 0.2, 0.5, 1.0, 1.5, 2.0, 2.5 and 3 g of laterite soil in the process to identify the optimum soil dosage. the solutions were shaken at 120 rpm for 1 hour, and the remaining phosphate concentrations were measured. 2.4 determination of the optimum phosphate concentration to determine the optimum phosphate concentration, series of phosphate solutions were prepared as 0.2, 0.4, 0.6, 0.8, 1, 5, 10, 15, 20, 30, 40 and 50 ppm. 1 g of laterite soil was mixed with 50 ml of solutions and were shaken at 120 rpm for 24 hours. the remaining phosphate concentrations were measured. 2.5 determination of the optimum contact time 50.0 ml of 0.8 ppm phosphate solutions were mixed with 1 g of soil and optimum contact time was observed at different time intervals to find out the optimum contact time for the low concentration. the same procedure was followed for the high concentration phosphate (50 ppm). the solutions were shaken at 120 rpm and the remaining phosphate concentrations were measured. 2.6 determination of the optimum ph then optimum ph of phosphate removal by laterite soil was studied by adding 1 g of laterite soil in 50 ml of phosphate solution and it was shaken at 120 rpm for 3 hrs. the ph was adjusted by adding h2so4 acid and naoh drops. 1 g of soil sample was mixed with 50 ml of 0.8 ppm phosphate solution for the testing. the solutions were shaken at 120 rpm and the remaining phosphate concentrations were measured. 2.7 determination of the effect of salts for the determination of effect of salts of the phosphate absorption, salt solutions with 2 ppm concentrations were prepared. then 25 ml of the phosphate solution and 25 ml of salt solution (nacl, naf, na2co3, nacl, nano3, caco3, cacl2, cahco3) were mixed and added into the 1 g of laterite sample and kept 3 hrs. figure 1. determination of optimum soil dose 3. results and discussion varying initial soil amount, research was conducted to find out the optimum soil dosage required to attain the highest removal efficiency during laterite phosphate contact. variation in the 72 removal phosphate efficiency at different initial soil dosages is shown in figure 1. this figure shows the removal efficiency of phosphate increases rapidly with an increase in the amount of laterite due to greater availability of the surface area for the adsorption of phosphate. a significant increase in uptake was observed when the dose was increased from 0.3 to 3 g. the figure shows more than 88% higher rate of removal of phosphate and 3 g showed highest removal efficiency (91.98%). 1 g showed more than 90% removal efficiency at first. therefore 1 g of laterite soil was identified to continue the research. figure 2. determination of optimum phosphate concentration phosphate removal efficiency at different initial concentrations is shown in figure 2 and it is evident that more than 99% phosphate removal was seen in all cases. 0.8 ppm was showed highest removal efficiency (99.96%) from all phosphate concentrations. 5 ppm and 15 ppm solution also showed high values (99.95%) that were close to the results of the 0.8 ppm solution. removal efficiency, increased with the increment in the concentration, because the ratio of surface active sites to total phosphate increases and therefore the interaction of adsorbate with the active sites on the adsorbent surface were sufficient for efficient phosphate removal. figure 3. determination of optimum time figure 4. determination of optimum time for low phosphate concentration for high phosphate concentration figure 3 and 4 show the optimum contact time for low and high phosphate concentration respectively. the figure 3 shows more than 99% removal efficiency followed by a higher subsequent removal rate that gradually approached a constant. at 3 hours it showed the highest removal efficiency of 99.9%. the solution adsorption initiates the rapid removal at the start, while the rate tends to be slightly slowed down with the saturation of the adsorption sites at the late hours. the removal 73 efficiency of phosphate at low concentrations showed that the removal efficiency, increased up to 3 hours and decreased after 3 hours, where the curve seems to be flattened. figure 4 showed that more than 88% removal efficiency for high phosphate concentration and 7 hours showed the highest removal efficiency (89.35%). figure 5. determination of optimum ph the results obtained indicate that adsorption of phosphate on laterite increases with decreasing ph, with the highest removal efficiency (99.99%) obtained at ph 7.5 and 99.8% removal efficiency obtained at ph 4.3 and ph 5. the amount of phosphate ions removed from solution by at low ph values was higher than that removed by laterite at high ph values. lowest removal efficiency (90.76%) was obtained at ph 11.1. this observation can be attributed to the effects of solution ph on phosphate speciation and charge development on the laterite surface. figure 6. determination of effect of salts phosphate adsorption on laterite soil was investigated in the presence of following competing salts: naf, na2co3, nano3, nacl, na2so4, caco3, cacl2 and ca(hco3)2. the eight competing salts had a different adverse effect on phosphate removal. the phosphate adsorption of laterite soil follows the order: naf>cacl2>caco3>nano3>ca(hco3)2>nacl>na2so4>na2co3 respectively. among the eight salts, all the salts had not largest impact on the adsorption of phosphate. 74 usage of laterite soil as an adsorbent to remove contaminants from water has several advantages. the main benefit is, the lower cost. other adsorbents require intense purification, preparation, and activation before use in practical applications. however laterite, in its raw form showed significantly high phosphate removal efficiency without any of these steps. this is one reason for the lower cost. it has also been seen that laterite soil is readily available in countries such as sri lanka (dissanayake, 1980), india (kumar, 2008), and china (zhang et al., 2014), which is beneficial and cost effective. other than that, as laterite soil is a natural adsorbent, no environmental damage is anticipated during the preparation stages. similar studied have been conducted by using laterite soil available in china (zhang et al., 2014), however, the phosphate removal efficiency of sri lankan raw laterite is very much higher. 4. conclusion adsorption studies were conducted to investigate the adsorption capacity of laterite under different conditions. based on the result of studies, laterite can be used as an adsorbent for the removal of phosphate from the solutions. laterite is easily available in large quantities and the treatment method of adsorption seemed to be economical. there is no need for the pre-treatment of the laterite with any chemicals such as acid or base. this minimizes the cost of adsorbent preparation. laterite proved to be an effective adsorbent and removal capacity was found around 90%. the phosphorus removal increases with adsorbent dosage. study of the adsorption as a function of contact time showed that 3 hours was sufficient time for maximum removal of phosphate. ph value is an important factor affecting the adsorption of phosphate on laterite. acidic environment (ph=1-5) is favorable to the adsorption of phosphate. the amount of adsorption decreases with increasing ph value of the solution. the results concluded that laterite soil has a higher removal efficiency for all the given conditions. acknowledgement this study was conducted under the ahead ice grant. our special thanks to world bank ahead project for funding. references binder, c.r., de baan, l. and wittmer, d., 2009. phosphorflüsse in der schweiz: stand, risiken und handlungsoptionen. abschlussbericht. umwelt-wissen, 0928. brian, o. 2005. what are phosphates? university center for environmental quality, geoenvironmental sciences and engineering department: phosphate and water quality. carneiro, f.m., nabout, j.c., vieira, l.c., roland, f. and bini, l.m., 2014. determinants of chlorophyll-a concentration in tropical reservoirs. hydrobiologia, 740: 89-99. chislock, m.f., doster, e., zitomer, r.a. and wilson, a.e., 2013. eutrophication: causes, consequences, and controls in aquatic ecosystems. nature education knowledge, 4: 10. daniel, t.c., sharpley, a. n., and lemunyon, j. l., 1998. agricultural phosphorus and eutrophication: a symposium overview. journal of environmental quality, 27: 251-257. dissanayake, c.b., 1980. mineralogy and chemical composition of some laterites of sri lanka. geoderma, 23: 147-155. donald, d.b., bogard, m.j., finlay, k. and leavitt, p.r., 2011. comparative effects of urea, ammonium, and nitrate on phytoplankton abundance, community composition, and toxicity in hypereutrophic freshwaters. limnology and oceanography, 56: 2161-2175. eaton, a.d., clesceri, l.s., rice, e.w., greenberg, a.e. and franson, m.a.h. eds., 2005. standard methods for the examination of water and wastewater. egle, l., zoboli, o., thaler, s., rechberger, h. and zessner, m., 2014. the austrian p budget as a basis for resource optimization. resources, conservation and recycling, 83: 152-162. el-sergany, m. and shanableh, a., 2012. phosphorus removal using al-modified bentonite clayeffect of particle size. asia pacific conference on environmental science and technology advances in biomedical engineering, 6: 323-329. 75 engelhardt and richard a.,2010, new directions for archaeological research on the angkor plain: the use of remote sensing technology for research into ancient khmer environmental engineering. unesco, 8. hamdi, n. and srasra, e., 2012. removal of phosphate ions from aqueous solution using tunisian clays minerals and synthetic zeolite. journal of environmental sciences, 24: 617-623. johnson, p.t., chase, j.m., dosch, k.l., hartson, r.b., gross, j.a., larson, d.j., sutherland, d.r. and carpenter, s.r., 2007. aquatic eutrophication promotes pathogenic infection in amphibians. proceedings of the national academy of sciences, 104: 15781-15786. maji, s.k., pal, a. and pal, t., 2008. arsenic removal from real-life groundwater by adsorption on laterite soil. journal of hazardous materials, 151: 811-820. mueller, d.k., 1995. nutrients in ground water and surface water of the united states: an analysis of data through 1992. 95: 4031. tilman, d., fargione, j., wolff, b., d'antonio, c., dobson, a., howarth, r., schindler, d., schlesinger, w.h., simberloff, d. and swackhamer, d., 2001. forecasting agriculturally driven global environmental change. science, 292: 281-284. yeoman, s., stephenson, t., lester, j.n. and perry, r., 1988. the removal of phosphorus during wastewater treatment: a review. environmental pollution, 49: 183-233. zhang, l., wu, w., liu, j., zhou, q., luo, j., zhang, j. and wang, x., 2014. removal of phosphate from water using raw and activated laterite: batch and column studies. desalination and water treatment, 52: 778-783. https://web.archive.org/web/20090922103448/http:/ejournal.anu.edu.au/index.php/bippa/article/viewfile/440/429 https://web.archive.org/web/20090922103448/http:/ejournal.anu.edu.au/index.php/bippa/article/viewfile/440/429 https://web.archive.org/web/20090922103448/http:/ejournal.anu.edu.au/index.php/bippa/article/viewfile/440/429 microsoft word 7 nigeria paper borokini et al., /journal of tropical forestry and environment vol. 2, no. 01 (2012) 69-76 69 case study community-based forest resources management in nigeria: case study of ngel nyaki forest reserve, mambilla plateau, taraba state, nigeria t.i. borokini* 1 , f.d, babalola 2 , t.o. amusa 3 , s.t. ivande 4 , z.j. wala 4 , o.o. jegede 5 , d. tanko 6 , and j.o. ihuma 7 1 national centre for genetic resources and biotechnology, p.m.b 5382, ibadan, nigeria 2 department of forest management and policy, university of ilorin, ilorin, nigeria 3 forestry research institute of nigeria (frin), new bussa, nigeria 4 ap leventis ornithological research insitute (aplori), jos, nigeria 5 nigeria conservation foundation (ncf), lagos, nigeria 6 ahmadu bello university (abu), zaria, nigeria 7 department of biological sciences, bingham university, nigeria date received: 18-12-2011 date accepted: 28-03-2012 abstract in nigeria, human communities are found within or beside forest ecosystems, depending on these ecosystems for survival. their forest exploitation is considered a threat to conservation efforts, leading to constant conflicts between government, law enforcement agencies and the communities. the best solution is a win-win system of participatory community-based forest resources management, in which the communities are regarded as stakeholders rather than as threats. this paper explains the adoption of this approach in ngel nyaki forest reserve, mambilla plateau, where the communities were trained in establishment and management of forest plantations with readily available market for their timber; employment for some of the community youths as well as community development projects. this paper calls for the adoption of this system in other protected areas in nigeria, while the government should provide basic amenities for the communities as alternatives to those forest products. keywords: community-based forest management, ngel nyaki forest reserve, protected areas, nigeria. 1. introduction from time immemorial, human settlements have been associated with tropical forests, and to date, in nigeria, human settlements are found within or beside forest regions, mostly the rural dwellers, whose lives and existence are solely dependent on the forests and their resources. for instance, in omo biosphere reserve, southwest nigeria, there are about 20 enclaves inside the reserve, mainly located on the periphery, and four timber camps and one small town. there are an estimated 20,000 inhabitants living inside the reserve (amador and uijetwaal, 1997) and during the dry season there is a temporary influx of hausa people from the north, igbo people from the east and non-nigerians (perrson and warner, 2003). greengrass (2006) noted that most of the inhabitants are farmers and timber workers, indicating that their livelihood depend on the forests. *corresponding author: tbisrael@gmail.com, tel: +23 4805 4506902 issn 2235-9370 print / issn 2235-9362 online ©2012 university of sri jayewardenepura borokini et al., /journal of tropical forestry and environment vol. 2, no. 01 (2012) 69-76 70 nigerian moist forests are rich in epiphytic ferns and orchids, and contain over 560 species of trees which attain heights of at least 12 metres and girth of 60 centimetres. due to the relatively large number of plant species identified, nigeria has been ranked the 11th in biodiversity in africa. in addition, the west african forests is one of the 25 biodiversity hotspots of global significance for conservation priorities (myers et al., 2000) and the nigerian tropical rainforests form a significant part of this (borokini et al., 2010). however, due to massive logging, fuelwood harvesting, poaching and expansion of agricultural lands, nigeria is losing many of her natural forests and their wildlife. nigeria was adjudged to have the highest rate of deforestation of primary forests having lost 55.7% of her natural forests between 2000 and 2005 (fao, 2006). the fao 2005 forest resources assessment further revealed that, poor tropical countries have the highest rate of deforestation (fao, 2006). as a result, as many as 58 (10.4%) of the tree species are listed as endangered (formecu, 1999). this biodiversity loss occurs in spite of the establishment of forest reserves, protected areas and associated conservation and environment laws. this indicates partial or total failure of these legal and institutional frameworks for nature conservation in nigeria. a good example of this was reported by greengrass (2006) in her studies on chimpanzees in southwest nigeria, that in most of the forest reserves visited, the state and local forest departments are unable to control the large-scale illegal activities taking place within the forest reserves. while the timber industries are being blamed for the illegal and excessive logging, the rural dwellers are accused of deforestation for fuelwood and farmland expansion. however, it is difficult, if not totally impossible to stop rural dwellers that live close to the forest from entering the forests because of conservation laws. these people have been depending on the forests from several centuries back and worse still, their illiteracy and poverty level is very high. over 70% of the population in sub-saharan africa (ssa) lives in rural areas where most households depend on forests and woodlands for their livelihoods (topa, 2005). while agricultural activities meet most of their subsistence needs, forest products—timber and non-timber forest products (ntfps)—provide a substantial part of the disposable income for at least 20 percent of rural families. in many protected areas in nigeria, there are active or passive conflicts on natural resource control between the government/government staff and the rural dwellers. the only viable solution is to consider these local people as stakeholders for effective conservation of these natural ecosystems earmarked as protected areas. this concept is called community-based forest resources management (cbfrm), which is synonymous to community-based natural resources management (cbnrm), or simply called community forestry. community forestry was defined by fao as “any situation which intimately involves local people in a forestry activity. it embraces a spectrum of situations ranging from woodlots in areas which are short of wood and other forest products for local needs, through the growing of trees at the farm level to provide cash crops and the processing of forest products at the household, artisan or small industry level to generate income, to the activities of forest dwelling communities” (fao, 1978). it primarily entails involving the local communities in conservation of the forests around them, training them on tree plantation and management, integrating tree planting with food crop cultivation (agroforestry), employment of some of the local people as staff of the protected area, community development projects as well as involving the people in the formulation of conservation policies. currently, the practice of cbnrm is very limited in nigeria (babalola, 2009). taungya system was probably the oldest method of community participation in forest management, introduced by richard st. barber baker in 1926 (bada, 1999). since then, several other practices such as agroforestry have been introduced, but it appears that most of these practices are not being used in most of the protected areas in nigeria. furthermore, as much as agroforestry is effective in forest management, it does not consider or favour other important biological components of the forest borokini et al., /journal of tropical forestry and environment vol. 2, no. 01 (2012) 69-76 71 ecosystem, such as the wildlife, shrubs, herbs and epiphytes, which have their equally important economic and ecological significance. therefore, this paper describes community participation in the management of ngel nyaki forest reserve, as a way to advocate for best practices in community forest management in nigeria. 2. ngel nyaki forest reserve ngel nyaki is located towards the western escarpment of the mambilla plateau. mambilla plateau is the highest plateau in nigeria with the mean altitude of 1,524metres (5,000 feet) above the sea level, while some hills are much higher, such as chappal waddi (the highest mountain in nigeria) which is 2,419 metres (7,936 feet) high. mambilla plateau is located in taraba state, north-eastern part of nigeria, and it is characterised by semi-temperate climate. there are about 15 forest fringes on the mambilla plateau, which include ngel nyaki forest reserve, leinde fadali, sarkaka, ndum yaji, and other fringing forests; but ngel nyaki forest reserve is the most diverse forest (chapman & chapman 2001). figure 1 shows the location of all the protected areas, including ngel nyaki forest reserve on mambilla plateau. ngel nyaki forest is made up of a main forest and three forest fragments separated by hills covered by montane grasslands. the reserve is situated between latitudes 07° 05’n and longitude 011° 05’e at an altitude of 1,400m – 1,600m above sea level. the reserve occupies about 46km 2 area of land, with about 7.2 km 2 of sub-montane to midaltitude forest. it was gazetted a local authority forest reserve under gashaka mambilla native authority forest reserve order of 24 april 1969. plate 1 shows the topography and part of the forests in ngel nyaki forest reserve. figure 1: map showing mambilla plateau, taraba state, nigeria (source: chapman and chapman, 2001) ngel nyaki forest harboured several threatened species and others unknown at that time elsewhere in west africa (anthonotha noldeae, apodytes dimidiata and pterygota mildbraedii) and nigeria (ficus chlamydocarpa and isolona cf. deightonii) (dowsett-lemaire, 1989). this diverse forest flora was reflected in the high number of primates and other animal species, and high bird species diversity (hall 1976, ash et al., 1989). over 146 vascular plant species have been identified and collected by dr. j.d chapman, many of which are trees and are endemic to the afromontane region. borokini et al., /journal of tropical forestry and environment vol. 2, no. 01 (2012) 69-76 72 furthermore, some of them are listed in the iucn red data – entandrophragma angolense, lovoa trichiloiodes, millettia conraui and pouteria altissima – some others are new additions to the west africa flora – pterygota mildbraedii, anthonotha noldeae and apodytes dimidiata. furthermore, plants such as isolona cf deightonii and ficus chlamydocarpa are new to nigerian flora. till date, there are still many plants in the forest that are yet to be identified, and they are suspected to be new plants (chapman and chapman, 2001). plate 1: photograph showing a section of ngel nyaki forest reserve associated with the wide floristic diversity are corresponding faunal diversity of large several herds of tantalus monkeys, duikers, birds, colobus monkeys, mountain gorillas, the red data listed chimpanzee, pan troglodytes subsp. vellerosus, putty nose monkeys (cercopithecus nictitans cf subspecies martini) and black and white colobus monkeys (colobus guereza occidentalis). oates (2000, pers. comm.) noted that the chimpanzees in the montane and submontane forests belong to the distinct subspecies pan troglodytes vellerosus listed as ‘endangered’ by the iucn primate specialist group (iucn, 2000). he also noted that the putty-nose monkey (cercopithecus nictitans, cf subspecies martini) needs taxonomic review and suspects that the mambilla putty noses may be different from those in the gashaka lowlands. furthermore, 10 buffalo syncerus caffer were also sighted. ngel nyaki is also classified as an important bird area (fishpool and evans, 2001). snakes and other terrestrial reptiles are very rare there due to the very cold weather on the plateau which is unfavourable to the poikilothermic nature of the snakes. the table 1 gives a list of the economic plants found in the area that are listed in the iucn red data list (iucn 2000). plate 2 depicts the some of the biodiversity of the ngel nyaki forest reserve. 3. community-participation in forest management in ngel nyaki forest 3.1 the people the area is populated by mambilla people and fulani herders. the mambilla people are primarily farmers. yelwa village appears to be the closest to the ngel nyaki forest reserve, a distance of about 40 minutes trekking. they cultivate maize for corn flour meal (tuwo). mairiga (pers. comm.) stated that ‘nyaki’ means ‘bean’, suggesting that they might have been cultivating beans in the past. the major agricultural crops here are coffee and tea, which are cultivated and sold in large quantities. mambilla plateau is the home to nigeria and west africa’s only highland tea plantations. towns on the mambilla plateau are small with populations ranging from 100 to 5,000 people, which include gembu (the largest town), dorofi, nguroje, ngelforo, wakili buba and maisamari. other agricultural crops include plantain, a special variety of pepper which when ripe, the flesh is yellowish-orange instead of the common red colored ripe pepper fruits; and a special variety of yam that resembles cocoyam. the borokini et al., /journal of tropical forestry and environment vol. 2, no. 01 (2012) 69-76 73 fulani people are cattle herders settling on the hills where they get grass for their animals. they also sell raw milk, cheese and yoghurt. table 1: list of plants in ngel nyaki forest reserve that are present in the iucn 2000 red data list s/n plant name family 1 peucedanum angustisectum (engl.) norman apiaceae 2 lobelia columnaris hook. f. campanulaceae 3 wahlenbergia ramosissima (hemsley) thulin sub-sp ramosissima campanulaceae 4 bafutia tenuicaulis c.d adams asteraceae 5 helichrysum cameroonense hutch & dalziel asteraceae 6 vernonia bamendae c.d adams asteraceae 7 stachys pseudohymifusa sebsebe subsp saxeri y.b harv. lamiaceae 8 crotalaria bamendae hepper leguminosae 9 crotalaria ledermanii baker f. leguminosae 10 millettia conraui harms leguminosae 11 entandrophragma angolense (welw.) c.dc meliaceae 12 khaya grandifoliola c.dc meliaceae 13 lovoa trichilioides harms meliaceae 14 eugenia gilgii engl. & brehm myrtaceae 15 polygala tenuicaulis hook f. subsp. tayloriana j. paiva polygalaceae 16 prunus africana hook f. rosaceae 17 chassalia laikomensis cheek ined. rubiaceae 18 pouteria altissima (a. chev.) baehni sapotaceae 19 dombeya cf. ledermanii sterculiaceae 20 carex preusii k. schum cyperaceae 21 eriocaulon asteroids s.m phillips eriocaulaceae 22 eriocaulon bamendae s.m phillips eriocaulaceae 23 raphia mambillensis otedoh araceae 24 xyeris sp. xyridaceae 25 irvingia gabonensis irvingiaceae 3.2 community participation in forest management when ngel nyaki forest was to be designated a forest reserve, yelwa community was relocated to its present location, perhaps one of the very few successful relocation of communities from the forest in nigeria. later, nigerian montane forest project (nmfp) was established by the university of christchurch, new zealand for research in biodiversity conservation and forest ecology. ngel nyaki forest reserve appears to be safe from deforestation and bush meat hunting. several of the yelwa community and staff of nmfp were interviewed informally in addition to personal observations, yielding the following explanations: 1. forest plantations: several local communities, including yelwa, were trained in planting, seedling and field management of fast woods, especially eucalyptus spp. (figure 2) which they grow in large quantity and within 6-10 years, they harvest and transport them to nearby towns, such as gembu, mutum biyu, jalingo, katsina ala, makurdi and other areas in the northeastern nigeria. the timber from eucalyptus is used for building and construction purposes, as well as the young boles are used as poles and mainly as firewood. this was observed as a great source of income to the people because eucalyptus is a fast growing wood. harvesting was done in such a way that the felled tree can regenerate naturally. in this way, no one goes into the forests to fell the trees. borokini et al., /journal of tropical forestry and environment vol. 2, no. 01 (2012) 69-76 74 plate 2: photographs illustrating the biodiversity of ngel nyaki forest reserve 2. employment: virtually all the staff of the forest reserve and nmfp are local people of yelwa community. this makes security of the forest reserve very effective and it also enhances community cooperation with the forest reserve staff. 3. community development project: funded by the essomobil oil company, the nmfp built a nursery school for the yelwa community. this was not available in the community before then, and it was made free for them to allow their children have access to education. several other areas of community forestry that need to be given serious consideration in nigeria include working out a sharing formula between the government and the local communities for the proceeds from the sales of forest resources or tourism; for which the local communities must have a a dominant shrub on the mountains a tree fern an orchid species bryophytes growing on a tree a pack of “shy” tantalus monkeys forest escarpment borokini et al., /journal of tropical forestry and environment vol. 2, no. 01 (2012) 69-76 75 larger share. furthermore, local people should be encouraged to make and sell local wares, like arts and crafts to tourists that visit protected areas around them, community development projects such as production of methane (biogas) from waste products and dumps for energy generation to replace fuelwood harvesting and burning. in addition, biodiversity offset projects, in which industries help financing biodiversity conservation projects as a way of paying for industrial wastes they release into the environment is very limited in nigeria. only very few industries are funding biodiversity projects. figure 2: eucalyptus plantation managed by the yelwa community 4. conclusion unless the local communities neighbouring protected areas are considered an important stakeholder in the management of the protected areas, there can never be a successful conservation of the nation’s biodiversity. the most effective way to do this is to give these local people a cheaper and more accessible alternative to the resources they get from the forests – mainly fuelwood and bush-meat in addition to community development projects, employments in the protected areas to their people, sharing of proceeds from the forests with the communities for sustainable development projects, favourable land policies to encourage land ownership for individual afforestation micro-businesses and source of livelihood, which may be through small-scale businesses, afforestation projects, bushmeat rearing among others. it should be noted that full cooperation of these communities are pivotal to successful biodiversity conservation. acknowledgment the study was funded through the 2010 small grant progamme of tropical biology association (tba). we are also grateful to dr. hazel chapman, director of nigerian montane forest project, for granting us the permission to conduct the research in ngel nyaki forest reserve. references amador, m.r., uijetwaal, a.a.c., 1997. towards a sustainable management of the omo forest reserve, ogun state, nigeria. unpublished report, nigerian forest elephant group. borokini et al., /journal of tropical forestry and environment vol. 2, no. 01 (2012) 69-76 76 ash, j.s., dowsett, r.j., dowsett-lemaire, f. 1989. new ornithological distribution records from eastern nigeria. in dowsett, r.j. tauraco research report 1. tauraco press, ely, uk. babalola, f.d. 2009. joint forest management (jfm): opportunity for implementation of rural development in cross river state, nigeria. african scientist 10 (3): 127-137. bada, s.o, 1999. community participation in the management of omo forest reserve. prepared for formecu, federal department of forestry, abuja, nigeria, 23-30. borokini, t.i., okere, a.u., giwa, a.o., daramola, b.o., odofin, w.t., 2010. biodiversity and conservation of plant genetic resources in field genebank of the national centre for genetic resources and biotechnology, ibadan, nigeria. international journal of biodiversity and conservation 2(3): 037-050. chapman, j.d., chapman, h.m., 2001. the forests of taraba and adamawa states, nigeria. an ecological account and plant species checklist. university of canterbury, christchurch, new zealand, 5-27. dowsett-lemaire, f., 1989. physiography and vegetation of the highland forests of eastern nigeria. tauraco research report, 1, 6–12. greengrass e.j., 2006. a survey of chimpanzees in south-west nigeria. ncf-wcs biodiversity research programme. unpublished report. fao., 1978. forestry for local community development. forestry paper 7, fao, rome. fao. 2006. global forest resources assessment 2005. fao forestry paper 147, rome. fishpool, l.d.c., evans, m.i., 2001. important bird areas in africa and associated islands. pisces publications, newbury, uk, 42-46. formecu, 1999. forest resources study, nigeria. revised national report vol. 2. prepared for formecu by beak and geomatics international, 87-99. hall, p. 1976. the birds of mambilla plateau. bulletin of the nigerian ornithological society, 12, 67– 72. iucn 2000. iucn red data list categories. iucn, gland, switzerland. myers n., mittermeier ra., mittermeier cg., de fonseca gab., kent j., 2000. biodiversity hotspots for conservation priorities. nature 403. perrson, h.m., warner, m.d., 2003. the chimpanzees and other primates of omo forest reserve. the nigerian field 68: 160-167. topa g., 2005. framework for forest resource management in sub-saharan africa. africa region working paper series number 89. the world bank. 137pp. jayakody et al. /journal of tropical forestry and environment vol. 9, no. 02 (2019) 93-100 93 composition analysis of selected sri lankan seaweeds m.m jayakody1, m.p.g vanniarachchy1*, i. wijesekara1 1department of food science & technology, faculty of applied sciences, university of sri jayewardenepura, gangodawila, nugegoda, sri lanka date received: 12-11-2018 date accepted: 20-12-2019 abstract seaweeds are a rich source of health beneficial bioactive nutraceuticals and currently they are under-utilized in sri lanka. in the present study, proximate analysis of seaweed varieties chnoospora minima and porphyra sp. obtained from mirissa, matara, sri lanka and ulva fasciata was taken from point dondra matara, sri lanka on june, 2018 were investigated. the moisture content, total fat content, protein content and ash content were determined according to the official methods of analysis by association of official analytical chemists after drying for 8h at 600 c. the results revealed that the moisture contents (%) of chnoospora minima, porphyra sp. and ulva fasciata were 13.24 ± 0.20, 14.30 ± 0.14 and 18.11 ± 0.01 respectively. total fat contents (%) of chnoospora minima, porphyra sp. and ulva fasciata were 0.21 ± 0.11, 0.19 ± 0.03 and 0.28 ± 0.05 respectively. protein contents (%) of chnoospora minima, porphyra sp. and ulva fasciata were 13.70 ± 0.2, 21.14 ± 0.04 and 11.84 ± 0.1. total ash contents (%) of chnoospora minima, porphyra sp. and ulva fasciata were 17.20 ± 0.24, 5.40 ± 0.7 and 18.05 ± 0.21 respectively. total carbohydrate content (%) was analyzed according to the dubois method. chnoospora minima, porphyra sp. and ulva fasciata showed total carbohydrate content (%) as 3.87 + 0.66, 20.59 ± 0.24 and 7.68 ± 1.16 respectively. moreover, the sulphate content was analyzed according to the precipitate method. chnoospora minima, porphyra sp. and ulva fasciata showed 1.45 ± 0.35, 2.75 ± 0.07 and 4.54 ± 0.06, sulfate contents (%) respectively. in conclusion, highest ash content which indicates a good mineral content was observed in ulva fasciata and chnoospora minima. fibre, protein and carbohydrate contents are significantly different among the 3 samples. highest fibre content was observed in chnoospora minima. highest protein and carbohydrate contents were observed in porphyra sp. but there is no significant difference in fat contents among the three samples. keywords: chnoospora minima; porphyra sp.; ulva fasciata; proximate analysis; sulphur 1. introduction at present people are seeking more benefits from foods other than satisfying their hunger. thus the role of food in human health is gaining more attention over the last few years (gupta and abughannam, 2011). in that case, since seaweeds are an underutilized abundant food resource in sri lanka seaweed based products can be introduced as a good choice for consumption. the beneficial effects of food can be attributed to different compounds present in foods such as phenolic compounds, sulphated polysaccharides and organic acids which possess antioxidants, antimicrobial, antiviral and anticancer activity (gupta and abu-ghannam, 2011). though the chemical composition of seaweeds is not well known as the terrestrial plants but it is known to be rich in carbohydrates, protein and minerals as well as bioactive compounds such as polyphenols, terpenoids, carotenoids and tocopherols. seaweeds have been also reported to produce a great variety of metabolic compounds which are not produced by terrestrial plants. bioactive compounds which have been isolated and identified from seaweeds include sulphated polysaccharides (laminarins and fucoidans), polyphenols such as phlorotannins carotenoid pigments such *correspondence: mihiripg@sjp.ac.lk, issn 2235-9370 print / issn 2235-9362 online ©university of sri jayewardenepura doi: https://doi.org/10.31357/jtfe.v9i2.4471 94 as fucoxanthin and astaxanthin, sterols and mycosporine-like amino acids. (gupta and abu-ghannam, 2011). generally seaweeds can be classifies in to 3 main groups according to their pigmentation as bro wn (phaeophyta), red (rhodophyta), and green (chlorophyta) seaweeds (chan, ho and phang, 2006). seaweed is a food source which contains protein, lipids, vitamins and minerals. it is stated that this nutrient content varies depending on the type of species, the time of collection, geographic habitat, and ambient conditions such as water temperature and light intensity as well as nutrient concentration in water (marsham, scott and tobin, 2007). studies have been revealed that seaweeds are rich with polysaccharides. these seaweed polysaccharides cannot be entirely digested by human intestinal enzymes. hence they are regarded as fibre rich food ingredients. together with their low lipid content, seaweeds only provide a very low amount of energy. consumption of seaweeds can increase the intake of dietary fiber and lower the occurrence of some chronic diseases (diabetes, obesity, heart diseases, cancers), which are associated with low fiber diets (wong and cheung, 2000). the protein in algae contains all the essential amino acids. (dawczynski, schubert and jahreis, 2007). matanjun et al., 2008 has also stated that, seaweeds contain all the essential amino acids in different proportions, except for tryptophan, which was destroyed during hydrolysis. thus the present study has done to get a general idea about the nutritional composition of chnoospora minima, porphyra sp. and ulva fasciata available in southern cost of sri lanka. 2. methodology 2.1. sample collection the seaweed samples of porphyra sp. and chnoospora minima seaweed varieties were manually collected during june, 2018 from mirissa, matara district, sri lanka (5°56'53.74" (5.9482on))and 80°28'17.71" (80.4715 oe)) and ulva fasciata from point dondra, matara district, sri lanka (5° 55' 7.9" (5.9189°n) and 80° 35' 24.8" (80.5902°e)) all the algal samples were harvested manually from the respective locations and then transported to the laboratory in polythene bags. they were thoroughly cleaned to remove epiphytes and detritus attached to the fronds and kept in a freezer till further use. finally algal samples were dried at 600c, in a drying cabinet for 8 hours. then they were pulverized into small particles, sieved through the 355micron (number 42) sieve. then they were stored in room temperature, sealed in polypropylene bags till further used in analysis. 2.2. determination of moisture content moisture content was determined by the infrared moisture analyzer (shimadzu, max 60g, d=0.001g) expressed as percentage by weight of sample. 2.3. determination of total ash (gravimetric method) total ash content was determined according to the aoac official method 923.03. approximately 5g of the samples were weighed into previously cleaned, dried and weighed porcelain crucibles. subsequently the samples were ignited slowly over a bunsen flame until no more fumes evolved. the dishes were then transferred in to the muffle furnace (wise therm) set at 550 0c and incinerated until it was free of black carbon particles and turns to white or grey in colour. the incinerated crucibles were cooled in the desiccator and the weight was recorded. ashing, cooling and weighing procedures were repeated until the difference between two successive weights was less than 1 mg. experiment was duplicated. finally the total ash percentage was determined by the following equation; jayakody et al. /journal of tropical forestry and environment vol. 9, no. 02 (2019) 93-100 95 ash % = weight of ash ash % = m3 m1 m2 m1 m1 = weight of the empty crucible m2 = weight of the crucible + sample before drying m3 = weight of the crucible + sample after drying 2.4. determination of protein content protein content was determined by micro kjeldhal method (aoac method 978.04) with following 3 main steps. those were acid digestion of samples, distillation of the samples followed by titration. during acid digestion 50mg of the sample were measured on to a tissue paper and folded such that samples do not come out. then the samples were digested separately at 420 0c for 3 hours in kjeldhal digestion flasks with 2.5 ml of conc. h2so4 and a kjeldhal tablet. after digestion the contents in the digesting tubes were transferred to the tube in the distillation unit one by one while supplying 32% naoh and distilled water to the distillation unit. during the distillation, the emitted gas was collected to 5ml of 4% boric acid solution with few drops of kjeldhal indicator in the medium. the gas trapped by 4% boric acid was titrated with 0.02 m standardized hcl and recorded the end point. protein content of the seaweed samples were calculated by the following equation. the experiment was triplicated. nitrogen (%) = (sample titre – blank titre ) x molarity of hcl x 14 x 100 weight of the sample taken x 1000 protein = nitrogen (%) x factor 2.5. determination of lipid content (soxhelt extraction method) lipid content was determined by the soxhelt extraction method. approximately 10g of finely ground sample was weighed to the nearest 0.1g into the motor and pestle and twice the weight of anhydrous sodium sulphate was added. the content was ground until a free flowing powder was obtained after which it was transferred in to the extraction thimble and covered with a cotton wool. the extraction thimble with the sample was placed in the soxhlet apparatus. a cleaned, dried and previously weighed round bottom flask (250 ml) containing 200 ml of petroleum ether with pumice chips and a condenser was connected to the soxhlet apparatus and refluxed for 5 hours keeping the heating rate low enough to prevent solvent escaping from the top of the condenser during the refluxing. after the refluxing was over, the solvent was distilled off and cooled the content with the flask and weighed. the process was repeated until a constant x 100 x 100 weight of the sample 96 weight was obtained. experiment was duplicated. the crude fat percentage of the sample was determined by the following equation, percentage of crude fat content of the sample = w1 f x 100 w2 w1 = weight of the flask with fat and chips. f = weight of the flask and the chips. w2 = weight of the sample 2.6. determination of total carbohydrate content (dubois method) the sugar content was determined by using modified method of (dubois et al., 1956). approximately 0.1g of pulverized sample which was measured by the analytical balance (agn220c max 220g, d= 0.0001g) was hydrolyzed at 100 0c in a water bath for 2 hours with 50ml of 2m hcl after which neutralized by 50ml of 2 m naoh. the neutralized solution was filtered through whatman no. 41 paper. 500 µl of filtrate and 500 µl of 20% phenol solution was added into a test tube followed by 2.5 ml concentrated sulfuric acid (analytical grade reagent). mixture was incubated for 10 min in room temperature. after incubation mixture was vortex vigorously for 10 seconds. then solution was again incubated in room temperature for 15 min, followed by 37 0c incubator for 30 minutes. absorbance was measured at a wavelength of 490 nm using uv mini-1240 spectrophotometer. blank solution was prepared following the same procedure as above replacing the sample with distilled water. the standard curve was drawn for dglucose from regression analysis using the software minitab r 17 by measuring the absorbance values corresponding to d-glucose concentration. experiment was triplicated for all the samples and standards. 2.7. determination of total fibre content total fibre content was calculated by the following equation; percentage of fibre content (m/m) = 100 (a+ b +c+d+e) a = percentage moisture content of the sample b = percentage total fat content of the sample c = percentage crude protein content of the sample d = percentage total carbohydrate content of the sample e = percentage total ash content of the sample 2.8. determination of sulphate content sulphate was determined using modified aoac gravimetric method (aoac,1995) with minor modifications. dry seaweed sample of 0.5g was transferred into a beaker with 10ml of concentrated hn03. the beaker was placed in hot plate and it was heated at 123 0c in a fume hood for 30 min to have the final volume of digest as 2-3 ml. after cooling the sample in fume hood 23 drops of 40% hcho solution were added to reduce the excess hno3. the mixture was filtered into 250ml conical flask and 0.5 ml concentrated hcl was added followed by distilled water to bring the volume to 200ml. the solution was heat to boiling and 10ml of 0.25 m bacl2 was added drop wise with constant stirring for 5 min and kept aside for 5h in a warm place, the baso4 solution was filtered with ash less whatman filter paper and precipitate was ashed in crucibles in muffle furnace at 560 0c for 24h. the crucibles were transferred jayakody et al. /journal of tropical forestry and environment vol. 9, no. 02 (2019) 93-100 97 to desiccator for cooling and weighed to determine the weight of baso4. the percentage sulphate was calculated from the following equation; sulphate (%db) = (0.4116 x a) b a = weight of baso4 b = weight of the sample 2.8. statistical analysis analysis was performed in duplicates except for the crude protein content. mean values of moisture, fat, protein, carbohydrate, ash and fibre were analyzed by one-way anova and tukey comparison at p < 0.05 by minitab 17 to detect significant differences among groups. 3. results table 1: moisture, fat, and protein contents of chnoospora minima, porphyra sp., and ulva fasciata seaweed variety moisture (%) fat (%) protein (%) chnoospora minima 13.24 + 0.20 c 0.21 + 0.11a 13.70 + 0.2b porphyra sp. 14.30 + 0.14b 0.19 + 0.03a 21.14 + 0.04a ulva fasciata 18.11 + 0.01a 0.28 + 0.05a 11.84 + 0.1c values are means ± sd of two determinations. different letters a, b and c in the same column indicate significant difference (p<0.05) table 2 : carbohydrate, ash and fibre contents of chnoospora minima, porphyra sp., and ulva fasciata seaweed variety carbohydrate (%) ash (%) fibre (%) chnoospora minima 3.87 + 0.66c 17.20 + 0.24a 51.77 + 1.03a porphyra sp. 20.59 + 0.24a 5.4 + 0.7b 38.24 + 1.08c ulva fasciata 7.68 + 1.16b 18.05 + 0.21a 44.04 + 0.77b values are means ± sd of two determinations. different letters a, b and c in the same column indicate significant difference (p<0.05) table 3 : sulphate content of chnoospora minima, porphyra sp. and ulva fasciata seaweed variety sulphate content (%) x 100 98 chnoospora minima 1.45 + 0.35c porphyra sp. 2.75 + 0.07b ulva fasciata 4.54 + 0.06a values are means ± sd of two determinations. different letters a, b and c in the same column indicate significant difference (p<0.05) 4. discussion the results revealed that the highest composition of analyzed seaweed varieties is comprised of fibre. the fibre content of the analyzed seaweed varieties are significantly different (p < 0.05) from each other. chnoospora minima has the highest fibre content among all the 3 varieties. dietary fibre is defined as an indigestible fraction which contains oligosaccharides and resistant starches, resistant proteins, and associated compounds such as polyphenols (jiménez-escrig and sánchez-muniz, 2000). generally fibre is not digested by the digestive enzymes. but this undigested portion will supply many health benefits to the body. fibre adds bulk to the diet, fibre will also attracts water and turns to gel during digestion there by traps carbohydrates and slows absorption of glucose hence it lowers variance in blood sugar levels, it also lowers total and ldl cholesterol etc. (dhingra et al., 2011). thus consumption of fibre rich food will enable the consumers to lead a healthy life. the results of the analysis revealed that the crude protein content of the samples significantly different among each other (p < 0.05). highest protein content was recorded in the red algae variety porphyra sp. (21.14 + 0.04). while lowest in the green algae u. fasciata (11.84 + 0.1) the results obtained from the analysis agree with fleurence, morançais and dumay, (2018) which states that the protein content of marine algae differs according to the species and low for brown seaweeds (3 ± 15% of dry weight), moderate for green algae (9 ± 26% of dry weight) and protein content is high for red seaweeds (maximum 47% of dry weight) (fleurence, morançais and dumay, 2018). the fat content of the all the analyzed seaweed varieties were not significantly different (p > 0.05). the data of fat content (%) remained in the range (<4% on dw) as reported earlier for various macro algal species. (kumari et al., 2010). the carbohydrate content (%) of chnoospora minima, porphyra sp. and ulva fasciata is represented in table 2. according to the results carbohydrate contents of the 3 seaweed varieties are significantly different (p < 0.05) recording the highest carbohydrate content 20.59 + 0.24 in porphyra sp. the phenol–sulfuric acid method is used to determine the carbohydrate content of the samples. it is a simple and rapid colorimetric method to determine total carbohydrates in a sample. this method determines virtually all classes of carbohydrates, including monosaccharides, disaccharides, oligosaccharides, and polysaccharides. although the method detects almost all carbohydrates, the absorptivity of the different carbohydrates varies. thus, unless a sample is known to contain only one carbohydrate, the results must be expressed arbitrarily in terms of one carbohydrate. in this method, the concentrated sulfuric acid breaks down any polysaccharides, oligosaccharides, and disaccharides to monosaccharide. pentoses (5-carbon compounds) are then dehydrated to furfural, and hexoses (6-carbon compounds) to hydroxymethyl furfural. these compounds then react with phenol to produce a yellowgold color. for products that are high in hexose sugars, glucose is commonly used to create the standard curve, and the absorption is measured at 490 nm. the color for this reaction is stable for several hours, it is said that the accuracy of the method is within ±2% under proper conditions. (nielsen, 2009). jayakody et al. /journal of tropical forestry and environment vol. 9, no. 02 (2019) 93-100 99 the table 3 represents the sulphate content of the 3 seaweed varieties. the sulphate contents of the 3 seaweed varieties are significantly different (p < 0.05) and the highest sulphate content has been recorded in u. fasciata as 4.54 + 0.06 according to certain research articles sulphates and chlorides are the main anions found in seaweeds. these are important constituents of charged polysaccharides in marine algae which related to high salt concentration in the environment. (gómez-ordóñez, alonso and rupérez, 2010). research report by rupérez and saura-calixto, (2001) has reported that physicochemical properties of dietary fibre in edible seaweeds are related to the hydrophilic nature of the charged polysaccharides. sulphated polysaccharides from edible marine algae are not toxic for humans and, especially fucans and alginic acid derivatives, are known to exhibit different biological properties, such as anticoagulant, anti inflammatory, antiviral, or antitumoral activities. (rupérez, ahrazem and leal, 2002). also, sulphated polysaccharides from brown and red seaweeds have been reported to exhibit antioxidant capacity in vitro and potentially could be used as natural antioxidants by the food industry (rupérez, ahrazem and leal, 2002). 5. conclusion all the 3 seaweed varieties, chnoospora minima, porphyra sp. and ulva fasciata are very good sources of dietary fibre while all the 3 seaweed varieties are poor in fat. the three varieties are also moderately good sources of carbohydrates, protein and minerals with a highest carbohydrate and protein content in porphyra sp. among the three. acknowledgment the authors wish to thank department of food science and technology of university of sri jayewardenepura for supplying necessary equipment and chemicals for the research. references chan, c., ho, c. and phang, s., 2006. trends in seaweed research. trends in plant science, 11:165-166. dawczynski, c., schubert, r. and jahreis, g., 2007. amino acids, fatty acids, and dietary fibre in edible seaweed products. food chemistry, 103:891-899. dhingra, d., michael, m., rajput, h. and patil, r., 2011. dietary fibre in foods: a review. journal of food science and technology, 49:255-266. dubois, m., gilles, k., hamilton, j., rebers, p. and smith, f., 1956. colorimetric method for determination of sugars and related substances. analytical chemistry, 28:350-356. fleurence, j., morançais, m. and dumay, j., 2018. seaweed proteins. proteins in food processing, pp.245-262. gómez-ordóñez, e., alonso, e. and rupérez, p., 2010. a simple ion chromatography method for inorganic anion analysis in edible seaweeds. talanta, 82:1313-1317. gupta, s. and abu-ghannam, n., 2011. recent developments in the application of seaweeds or seaweed extracts as a means for enhancing the safety and quality attributes of foods. innovative food science & emerging technologies, 12:600-609. 100 jiménez-escrig, a. and sánchez-muniz, f., 2000. dietary fibre from edible seaweeds: chemical structure, physicochemical properties and effects on cholesterol metabolism. nutrition research, 20:585-598. kumari, p., kumar, m., gupta, v., reddy, c. and jha, b., 2010. tropical marine macroalgae as potential sources of nutritionally important pufas. food chemistry, 120:749-757. marsham, s., scott, g. and tobin, m., 2007. comparison of nutritive chemistry of a range of temperate seaweeds. food chemistry, 100:1331-1336. matanjun, p., mohamed, s., mustapha, n. and muhammad, k., 2008. nutrient content of tropical edible seaweeds, eucheuma cottonii, caulerpa lentillifera and sargassum polycystum. journal of applied phycology, 21:75-80. nielsen, s., 2009. phenol-sulfuric acid method for total carbohydrates. food analysis laboratory manual, pp.47-53. rupérez, p., ahrazem, o. and leal, j., 2002. potential antioxidant capacity of sulfated polysaccharides from the edible marine brown seaweedfucus vesiculosus. journal of agricultural and food chemistry, 50:840-845. rupérez, p. and saura-calixto, f., 2001. dietary fibre and physicochemical properties of edible spanish seaweeds. european food research and technology, 212:349-354. wong, k. and cheung, p., 2000. nutritional evaluation of some subtropical red and green seaweeds. food chemistry, 71:475-482. hauchhum. /journal of tropical forestry and environment vol. 7, no. 02 (2017) 31-38 31 aboveground biomass and carbon stock assessment in forest stands of gmelina arborea roxb. in mizoram, north-east india r.hauchhum* department of forestry, mizoram university, tanhril, mizoram. date received: 02-09-2017 date accepted: 02-12-2017 abstract aboveground biomass and carbon stock in tropical forest play an important role in global carbon cycle. assessment of biomass and carbon pool in different forest stands may provide information in making decisions about the carbon management within the forest. gmelina arborea, a fast growing species that is widely distributed and an important timber species of mizoram has been chosen to assess its biomass and carbon stock. the present study was carried out to estimate the aboveground biomass and carbon stock in g. arborea in different forest stands of mamit district, mizoram, north-east india. the result shows that the total aboveground biomass ranged between 66-108 mg ha-1 and carbon stock (30.0053.20 mg c ha-1). the aboveground biomass and carbon stock was maximum in forest stands (site-iii) with highest tree density and diameter class of 30-40cm and 40-50cm indicating the forest site was mature and undisturbed. the result demonstrates that g. arborea contribute in carbon sequestration and helps in mitigating global warming. further, the aboveground biomass and carbon sequestration potential was greatly affected by the tree composition, population pressure and anthropogenic activities. keywords: aboveground biomass, carbon stock, diameter class, gmelina arborea, tropical forest 1. introduction forests are natural storehouses for biomass and carbon. forest ecosystem is one of the most important carbon sinks nature has provided; carbon is continuously removed from the atmosphere by forest ecosystem processes and stored both in vegetation and soils (mcguire et al., 2001). anthropogenic activities, conversion to agriculture and increase industries rapidly decrease the forests worldwide; these are responsible for increases in atmospheric concentration of co2 and other greenhouse gases, which in turn, are thought to be a primary source for global climate change (melillo et al., 1996). thus, forest ecosystem plays a vital role in the global carbon cycle by sequestering a huge amount of co2from the atmosphere. earlier studies indicate that the amount of carbon stored in plant biomass globally exceeds that of atmospheric co2, and nearly 90% of the plant biomass carbon is stored in tree biomass (mooney et al., 2001). the potential of co2 sequestration intricately linked with site quality, forest type, tree species and age of stand (huyand anh, 2008). biomass and carbon storage in forest ecosystems play significant role in the global carbon cycle (li et al., 2013: zhao et al., 2014). therefore, tree biomass play crucial role for understanding the potential future changes of the climate system. biomass analysis is an important assessment in the carbon cycle especially, carbon sequestration. recently, biomass is become an important element in understanding and estimating the carbon pools and fluxes of greenhouse gases from terrestrial biosphere associated with land use and land cover changes (cairns et al., 2003). *correspondence: ramchhanliana85@gmail.com tel: +91 9612322075 issn 2235-9370 print / issn 2235-9362 online © university of sri jayewardenepura 32 the aboveground tree biomass and below ground root biomass both need to be assessed to enable better estimations of total carbon (hamburg, 2000). forest biomass accounts for 85-90% of terrestrial vegetation (dixonet al., 1994) and the amount of biomass change considerably with land use, disturbance and variation in environmental conditions (canadell et al., 2007: luyssaertet al., 2007). forest ecosystems store carbon in the biomass through photosynthetic process, thereby sequestering carbon dioxide that would or else be present in the atmosphere in large quantity. undisturbed forest ecosystems are generally highly productive and accumulate more biomass and carbon per unit area compared to other land use systems like agriculture. thus, forest play key role in global carbon cycle (canadell et al., 2007; houghton, 2005) and aboveground biomass and carbon storage have been across different parts of the world (hoover et al., 2012; tang et al., 2012). many research works had been carried out to study biomass production and carbon stock of tropical forests in different tree species by actual harvest at different ages and allometric equations relating biomass with one or more tree dimensions (jain and ansari, 2012). in the scenario of global warming and climate change, it is very essential to assess the biomass production and carbon sequestration using non harvest techniques but through standing trees. therefore, in this study, a nondestructive approached is adopted to determine the biomass and carbon stock in standing of g. arborea. the present investigation aims to estimate the aboveground biomass and carbon stock of g. arborea in the tropical forest ecosystem of mamit district, mizoram to understand the potential of tropical forest to mitigate the climate change at regional level. 2. material and methods 2.1 site descriptions the study was conducted at four forest stands in damparengpui, amamit district situated in the western part of mizoram. the geographic position of the four study sites is: site-i (23°43.’07.19” n and 92°24’55.84” e, altitude=1318 ft), site-ii (23°43.’04.95” n and 92°24’42.19” e, altitude=1355ft), site-iii (23°43.’20.39”n and 92°24’43.02”e, altitude=1157ft) and site-iv (23°43.’27.65”n and 2°25’06.43”e, altitude=1117ft). the area of the study sites receives a high rainfall with 2660 mm annually and the temperature during summer ranged between 25-35º c and during winter season (5-15º c). soil type of the study area is colluvial, formed along the steeps sided slopes due to accumulation of soil forming materials on slope surface. the study area is a tropical deciduous forest with moderately and steeply slopes which are covered with natural vegetation of tree species like gmelina arborea, albizia procera, steculia villosa, ficus semicordata, bischofia javanica and schima wallichiietc. 2.2 field sampling, aboveground biomass, carbon estimation field sampling was carried out at the month of march, 2014 by laying 10 quadrats of 20×20m size randomly in each site, the girth of all trees present in the sample plot were measured using measuring tape at breast height (1.37 m) above the ground, and height of g. arborea was measured with the help of an instrument haga altimeter. the measured girth was converted into diameter using the formula (diameter=girth/л). volume was estimated by volumetric equations available in the literature (fsi, 1996). to obtain biomass of each individual species, volume of each tree was multiplied with specific gravity. the carbon stock in each individual tree (g. arborea) was estimated by multiplication of biomass with conversion factor of 0.45 (i.e. 45% of the biomass). core segment of the wood (extracted from g. arborea) from each site was employed to determine the specific gravity. the wood samples were kept in oven at 100° c for 24 hours and specific gravity of g. arborea was 0.56 which was used to estimate the aboveground biomass. calculation of the growing stock for each site was carried out using the formula given below. hauchhum. /journal of tropical forestry and environment vol. 7, no. 02 (2017) 31-38 33 𝑉𝑠𝑝 = 𝛴 𝑉𝑖 (1) (2) where: i = 1……… n. number of tree measured within sample plot vi = volume of single tree vsp = total timber volume within sample plot vph = timber volume per hectare a = area under the sample plot 3. results and discussion 3.1 vegetation structure, stand density and basal area the highest density of g. arborea was recorded in site-iii (310 trees ha-1) followed by site-iv (230 trees ha-1), site-i (220 trees ha-1) and site-ii (210 trees ha-1) (table 1). the mean diameter at breast height (dbh), tree height and basal cover of g. arborea at different sites were listed in table 1. table 1: tree species composition, density and basal cover at the four forest stands of the study site. site species mean dbh (cm) mean height (m) density basal cover (m 2 /ha) i gmelina arborea 37 16.43 220 23 albizia procera 35 6.5 stereospermum neuranthum 34 3.6 sterculia villosa 18 0.04 schima wallichii 16 0.43 garuga pinnata 36 4.1 glochidion arborescens 24 0.93 ii gmelina arborea 31 12.75 210 16.1 albizia procera 43 9.1 stereospermum neuranthum 41 6.7 sterculia villosa 14 0.65 garuga pinnata 23 0.86 bischofia javanica 17 0.71 schima wallichii 15 0.39 iii gmelina arborea 34 16.45 310 29.8 albizia procera 35 7.8 sterculia villosa 15 3 stereospermum neuranthum 36 22 glochidion arborescens 20 2.14 bischofia javanica 22 0.61 schima wallichii 19 1.54 iv gmelina arborea 31 17.95 230 21.3 albizia procera 30 5.9 sterculia villosa 15 0.78 bischofia javanica 18 0.78 schima wallichii 12 5.71 ficus semicordata 42 1.38 vsp × 10000 vph = ---------------------- a 34 the number of trees recorded in 20-30 cm and 30-40 cm diameter class was highest compared 4050 cm,on the other hand, only 4 g. arborea species in 50-60 cm diameter class was found in site-i but not in other study sites (figure 1). the decrease in number of trees in larger diameter class e.g. 40-50 cm and 50-60 cm of g. arborea may be the result of selective felling by the village people for timber and agriculture implements. it indicates large anthropogenic activities and disturbances by the village people in this area that results in forest degradation and deforestation. figure 1: number of trees (g. arborea) in different diameter class in four forests stands of mizoram. relationship of above ground biomass with dbh and height. the amount of aboveground biomass and carbon in different diameter class at different sites were depicted in table 2. the volume of trees increases with increase in diameter class, similarly, the amount of biomass and carbon storage. the amount of aboveground biomass and carbon content in 50-60cm diameter was relatively high with 42.32 mg ha-1 and 19.04 mg c ha-1 respectively. the aboveground biomass varied from 10.55-17.51 mg ha-1 in 20-30cm diameter class, 23.16-41.52 mg ha-1 in 30-40cm diameter class and 19.78-43.11 mg ha-1 in 40-50cm diameter class. the variations in aboveground biomass in different diameter class may be the result of changes in number of trees, species composition and basal cover across the study sites. the dbh of g. arborea significantly correlated with volume, aboveground biomass and carbon storage for all the sites at r2= 0.9686 for site-i, r2=0.9778 for site-ii, r2=0.9896 for site-iii and r2=0.9583 for site-iv (figure 2). similarly, the relationship of tree height with volume, aboveground biomass and carbon storage in g. arborea was tested and given in figure 3. the relationship of tree height with volume, biomass and carbon in site-i was (r2=0.4481), site-ii (r2=0.8580), site-iii (r2=0.6139) and site-iv (r2=0.6851)indicating that tree height has weak relationship compared to dbh with tree volume, aboveground biomass and carbon storage. table 2: aboveground biomass (mg ha-1) and carbon (mg c ha-1) in different diameter class at four forest stands of the study site. diameter site-i site-ii site-iii site-iv class (cm) biomass carbon biomass carbon biomass carbon biomass carbon 20-30 10.55 4.75 14.46 6.51 10.85 4.88 17.51 7.88 30-40 23.16 10.42 31.39 14.12 41.52 18.68 34.42 15.48 40-50 29.91 13.45 19.78 8.91 43.11 19.39 30.59 13.76 50-60 42.32 19.04 0 2 4 6 8 10 12 14 20-30 30-40 40-50 50-60 n o . o f g . a rb o re a tr e e s diameter class (cm) site-i site-ii site-iii site-iv hauchhum. /journal of tropical forestry and environment vol. 7, no. 02 (2017) 31-38 35 figure 2:regression analysis between diameter at breast height (dbh) with volume, aboveground (abg) biomass and carbon storage in g. arborea in different sites (a) site-i (b) site-ii (c) site-iii and (d) site-iv in tropical forest stands of mizoram. 3.2 variation in aboveground biomass and carbon stock in gmelina arborea the amount of total aboveground biomass was highest in site-iii with 118.00 mg c ha-1 followed site-i (106.00 mg c ha-1) and lowest was recorded in 66.00 mg c ha-1). these results demonstrate that the amount of aboveground biomass varied with site to site depending on the forest type, age of stands and tree density. however, on contrary to the present result, borah et al. (2013) reported that the aboveground in different species in tropical forest of cachar district, assom was not affected by the tree density. the amount of aboveground biomass in the present study are in agreement with earlier studies e.g. agus et al., (2001), bohre et al. (2013) and devagiri. (2013) but relatively lower compared to earlier studies in subtropical forests of manipur with biomass ranged between 179-246 mg ha-1 (thokchom and yadava, 2013), sub-tropical broad leave forest (130-255 mg ha-1) reported by yadava (2010). aboveground carbon estimation described in the literature suggests that carbon constitute between 45 to 50% of dry matter and it can be estimated by simply taking a fraction of biomass as (magnussen and reed, 2004). 𝐶 = 0.45 × 𝐵 (3) where: c = carbon content b =biomass. y = 0.5197x 10.564 r² = 0.9686 y = 0.2806x 5.7044 r² = 0.9686 y = 0.1263x 2.567 r² = 0.9686 -5 0 5 10 15 20 25 30 0 20 40 60 80 dbh (cm) volume abg biomass carbon(a) y = 0.4451x 7.941 r² = 0.9778 y = 0.2404x 4.2881 r² = 0.9778 y = 0.1082x 1.9297 r² = 0.9778 0 5 10 15 0 10 20 30 40 50 dbh (cm) volume abg biomass carbon(b) y = 0.489x 10.134 r² = 0.9901 y = 0.264x 5.4721 r² = 0.9901 y = 0.1188x 2.4625 r² = 0.9901 0 5 10 15 0 10 20 30 40 50 dbh (cm) volume abg biomass carbon(c) y = 0.4212x 7.7034 r² = 0.9554 y = 0.2274x 4.1599 r² = 0.9554 y = 0.1023x 1.8719 r² = 0.9554 -5 0 5 10 15 0 10 20 30 40 50 dbh (cm) volume abg biomass carbon(d) 36 in the present study we followed the above equation to assess the carbon stock in g. arborea at different sites in tropical forest area of mizoram. the total carbon stock range from 30.00 mg cha-1 to 53.20 mg cha-1with carbon content was highest in site-iii and lowest in site-ii. the lowest amount of aboveground biomass and carbon content in site-ii may be the result of low tree density, vegetation composition and anthropogenic disturbance compared to other sites. the age of forest may also influence the potential to sequester carbon (terakunpisut et al., 2007). on the other hand, increase number of trees, basal area, growing stock and presence of large number of 30-40 cm and 40-50 cm diameter class in site site-iii may be responsible for increase aboveground biomass and carbon stock. these indicate that siteiii was mature and less disturbed which favors the growth and development of these forests compared to other sites and have greater rate of carbon sequestration. the present study demonstrates that population pressure and tree density has significant impact on biomass and carbon stock in tropical forest. figure 3: regression analysis between tree height with volume, aboveground (abg) biomass and carbon storage in g. arborea in different sites (a) site-i (b) site-ii (c) site-iii and (d) site-iv in tropical forest stands of mizoram. table 3: basal area, total biomass, total carbon and total growing stock at four forest stands of the study site. site basal area (m 2 ha -1 ) total biomass (mg ha -1 ) total carbon (mg cha -1 ) total growing stock (m 3 ) i 23.00 106.00 47.70 196.30 ii 16.10 66.00 30.00 121.60 iii 29.80 118.00 53.20 218.80 iv 21.30 82.00 36.80 151.40 y = 0.757x 3.3728 r² = 0.4481 y = 0.4088x 1.8213 r² = 0.4481 y = 0.184x 0.8196 r² = 0.4481 0 5 10 15 20 25 30 0 10 20 30 height (cm) volume abg biomass carbon(a) y = 0.902x 5.5888 r² = 0.858 y = 0.4871x 3.0179 r² = 0.858 y = 0.2192x 1.3581 r² = 0.858 0 5 10 15 20 0 5 10 15 20 25 height (cm) volume abg biomass carbon(b) y = 0.8632x 7.4021 r² = 0.6139 y = 0.4661x 3.9971 r² = 0.6139 y = 0.2098x 1.7987 r² = 0.6139 0 5 10 15 0 5 10 15 20 25 height (cm) volume abg biomass carbon(c) y = 0.6765x 5.8266 r² = 0.6851 y = 0.3653x 3.1464 r² = 0.6851 y = 0.1644x 1.4159 r² = 0.6851 -5 0 5 10 15 0 10 20 30 height (m) volume abg biomass carbon(d) hauchhum. /journal of tropical forestry and environment vol. 7, no. 02 (2017) 31-38 37 4. conclusions the present study indicates that aboveground biomass and carbon storage in g. arborea at different sites in tropical forest was highest in forest stands with high tree density, basal area and growing stock. the presence of diameter class with 30-40 cm and 40-50 cm has greater potential to carbon sequestration compared to other diameter class. furthermore, the aboveground biomass and carbon has strong relationship with dbh compared to height of the tree. this indicates that the larger diameter class, the greater carbon sequestration which in turn significantly reduces the carbon level in the atmosphere. the result in the present study shows that g. arborea forest stands in tropical region has a great potential to sequester carbon and the amount of carbon sequestration depends on species composition and anthropogenic activities. acknowledgements author is thankful to university grants commission (ugc) for financial assistance in the form of rajiv gandhi national fellowship (rgnf) and department of forestry, mizoram university for proving laboratory facility. references agus, l., karyanto, o.,hardiwinoto, s.,na’iem, m.,kita,s.,haibarak., toda, h. 2001. biomass productivity and carbon stock in short rotation plantation of gmelina arborea roxb. in tropical forest. indonesian journal of agricultural sciences.1, 11-16. bohra, n., nath,a.j.,das, a.k. 2013. aboveground biomass and carbon stocks of trees species in tropical forests of cachar district, assom, northeast india. international journal of ecology and environmental sciences.39, 97-106. bohre, p., chaubey, o.p., singhal, p.k. 2013.biomass accumulation and carbon sequestration in tectonagrandislinn. f. and gmelinaarborearoxb. international journal of bio-science and biotechnology.5, 153-173. cairns, m.a., olmsted,l., gradanosj.,argaeg,j. 2003. composition and aboveground tree biomass of dry semi-evergreen forest on mexico’s yucatan peninsula. forest ecology and management.186, 125132. canadell, j.g., lequere, c.,raupach,m.r.,field, c.b.,buitenhuis, e.t.,ciais,p., j. conway,t., gillett,n.p.,houghton,a.r., morland,g. 2007. contribution to accelerating atmospheric co2 growth from economic activity, carbon intensity and efficiency of natural sink. proceeding of the national academy of science. usa.104, 18866-18870. devagiri, g. m., money, s.,singh,s.,dadhawal, v. k.,patil,p.,khaple,a. k.,devakumar, a. s.,hubballi,s.2013. assessment of above ground biomass and carbon pool in different vegetation types of south western part of karnataka, india using spectral modeling. tropical ecology.54, 149–165. dixon, r. k., brown, s., houghton, r.a., solomon, a.m.,trexler, m.c., wisniewki j. 1994. carbon pools and flux of global forest ecosystem. science, 263, pp 185-190. forest survey of india, 1996. volume equations for forests of india, nepal and bhutan. fsi, ministry of environment and forests, dehradun. hamburg, s.p. 2000. simple rules for measuring changes in ecosystem carbon in forestry-offset projects. mitigation and adaptation strategies for global change.5, 25–37. hoover, c.m., leak, w.b., keel, b.g. 2012. benchmark carbon stocks from old growth forests in northern new england, usa. forest ecology management.266, 108-114. huy, b., anh, t.a. 2008. estimating co2 sequestration in natural broad-leaved evergreen forest in vietnam. asia–pacific agroforestry news (fao).32, 7-10. 38 jain, a.,ansari, s.a. 2013.quantification by allometric equations of carbon sequestered by tectonagrandis in different agroforestry systems. journal of forestry research.24, 699-702. li, c., zha, t., liu, j., jia, x. 2013. carbon and nitrogen distribution across a chronosequence of secondary lacebark pine in china. forest chronology,89, pp 192–198 luyssaert, s., jung,m.,richardson, a.d., reichstein, m., papale, d., piao, s.l., schulze, e.d., wingate, l., matteucci, g., aragao,l.,aubinet,m.,beer,c.,bernhofer,c.,black, k.g.,bonal,d.,bonnefond, j.m.,chambers,j.,ciais,p.,cook,b., davis, k.j., dolman, a.j.,gielen,b.,goulden,m.,grace,j., granier,a.,grille,a.,griffs,t.,grunwald,t.,guidolotti,g., handson, p.j.,harding,r., hollinger, d.y., hutgra, l.r.,kolari,p.,krujit, b., kutsch,w.,lagergen, f., laurilla, t. 2007. co2 balance of boreal, temperate, and tropical forests derived from a global database. global change biology.13, 2509–2537. mcguire, a. d., sitch,s.,clein, j.s.,dargaville,r.,esser,g.,foley,j., wittenberg, u. 2001. carbon balance of the terrestrial biosphere in the twentieth century: analyses of co2, climate and land use effects with four process-based ecosystem models. global biogeochemical cycles.15, 183–206. melillo, j.m., hall, d.o.,agren, g.i. 1996. ‘executive summary’, in a. i. breymeyer, d. o. hall, j. m. melillo, and g. i. agren (eds.), global changes: effects on coniferous forests &grasslands, john willey & sons pub., ny. mooney, h., roy, j., saugier,b. 2001.terrestrial global productivity: past, present and future. academic press, san diego. tang, j. w., yin, j.x., qi, j.f.,jepsen, m.r.,lu, x.t. 2012. ecosystem carbon storage of tropical forests over limestone in xishuangbanna, sw china. journal of tropical forest sciences.24, 399-407. terakunpisut, j., gajaseni, n.,ruankawe, n. 2007. carbon sequestration potential in aboveground biomass of tong phaphun national forest, thailand. applied ecology and environmental research.5, 93-102. thokchom, a., yadava,p.s. 2013. biomass and carbon stock assessment in the sub-tropical forests of manipur, north-east india. international journal of ecology and environmental sciences.39, 107113. yadava, p.s. 2010. soil and vegetation carbon pool and sequestration the forest ecosystems of manipur, northeast india. in; qasim, s. z. & m. goel, (editors) carbon sequestration technologies for clean energy. daya publication house, new delhi, pp 163-170. zhao, j.,kang,f.,wang,l., yu, x., zhao, w., song, x., zhang,y., chen, f., sun,y., he, t., han,h. 2014. patterns of biomass and carbon distribution across a chronosequence of chinese pine (pinustabulaeformis) forests. plos one.9, e94966. issn 2235-9370 print / issn 2235-9362 online © university of sri jayewardenepura __________________________________________________ *correspondence: nabeysingha@gmail.com tel: +94 714444849 issn 2235-9370 print/issn 2235-9362 online ©university of sri jayewardenepura variation of water quality of four micro watersheds outlets in upstream of mahaweli river during maha cropping season n.s. abeysingha1*, m.i. madusanka1, b. rotawewa2 and n. gunasena2 1department of agricultural engineering and soil science, faculty of agriculture, rajarata university of sri lanka, anuradhapura, sri lanka 2food and agriculture organisation of the united nations, colombo 07, sri lanka date received: 11-07-2019 date accepted: 22-12-2019 abstract non-point source, agriculture based pollutants have been identified as one of the main cause for water pollution in sri lanka. naranhinna, pambadeniya kappeti-ela, and rajamale micro watersheds located in the kandy district have been identified by the project on rehabilitation of degraded agricultural lands in the central highlands implemented by food and agricultural organisation (fao) to rehabilitate through watershed management plan. this study assessed the baseline water quality status of these micro watersheds by obtaining water samples at the outlet of each watersheds during the maha cropping seasons 2018/2019. three replicates water samples from each outlets were collected six times and analysed for ec , ph, tds, co3 2-, hco3 -, no3 -, nh4 +, available p, total k, na, ca, mg, fe, al, as, cd, cr, mn, and pb using standard methods. most of the tested drinking water quality parameters in all four micro watersheds were within the permissible limits of world health organisation (who) standard except fe and nh4 +. observed fe contents exceeded the who limits (0.3 mg/l) of all watersheds and was in the range of 1.21.5 mg/l. concentration of nh4+ at kappeti ela, rajamale, and pambadeniya was in the range of 0.5 to 0.7 mg/l which exceeded the who standard (0.5 mg/l). using the tested parameters, study calculated drinking water quality index (dwqi) and also irrigation water quality index (iwqi) for all investigated micro watersheds for each of the sampling date. according to the guideline, mean dwqi (19 to 48.1) graded the water of all micro watersheds as excellent while iwqi (8.7-9.2) characterised them as excellent for any crops during the study period. keywords: drinking water quality, irrigation water quality, mahaweli river, micro-watersheds 1. introduction rivers in sri lanka can be considered as life blood of its economy and development as it plays a major role in irrigation, hydro power generation, municipal water supply, and also there are valuable freshwater ecosystems in association with the rivers in the country. discharge of pollutants without proper treatments to a river system from domestic sources, storm water discharges, industrial wastewaters, agricultural runoff and the other sources can have short term and long term detrimental effects on the quality of a river system (singh, 2007). the mahaweli river is the longest river in sri lanka which flows for 335 km covering about 16% of land area of sri lanka (withanachchi et al., 2014). it contributes to one seventh of sri lankas’ total runoff (hewawasam, 2010) and a succession of multipurpose reservoirs have been built to capture the runoff under mahaweli development programme. upstream mahaweli is the main water production area of the river and water reaching from these area is fast getting polluted due to unfavorable human activities. doi: https://doi.org/10.31357/jtfe.v9i2.4467 46 mailto:nabeysingha@gmail.com abeysinghe et al. /journal of tropical forestry and environment vol. 9, no. 02 (2019) 46-54 47 it is identified that the use of excessive amount of synthetic inorganic fertilizer, pesticides on crops and grasslands; raring of farm animals, especially cattle in the river basin, waste disposal to river, and soil erosion in cultivated lands and construction sites in the river basin as ways of water pollution (dissanayake and weerasooriya, 1986). land degradation especially from soil erosion has been identified as a major issue in upper mahaweli area (hewawasam, 2010). it is noted that mahaweli river receives large amount of harmful materials from highly polluted canals, side streams or drains (dissanayake and weerasooriya, 1986). river water quality also varies over both space and time (ai et al., 2015). upstream mahaweli water quality may be different from those of downstream mahaweli water. four micro watersheds naranhinna, kappeti ela, rajamale, and pambadeniya located in upper mahaweli area of kandy district have been selected to rehabilitate by the un fao funded project. monitoring water quality is crucial to understand watershed health and for establishing appropriate watershed management plan (charalampous et al., 2015). this rehabilitation project sought to know the variation of surface water quality of these micro watersheds before starting their land rehabilitation programmes. therefore, this study focused to investigate the status of water quality in four micro watersheds during the maha cropping season (september to march 2018/19), and also probe into the reasons for the variation. 2. materials and methods 2.1 study area this study was carried out in four micro-watersheds, naranhinna, kappetiya ela, rajamale, and pambadeniya located in deltota divisional secretariat (ds) division and doluwa divisional secretariat division in kandy district. figure 1 shows the spatial distribution of these micro watersheds in ds divisions. these watersheds were delineated taking the water quality monitoring places as outlets using arcgis 10.2 software. moreover, table 1 summarises the land use and land cover, area extent, number of farmers and some locational characteristics of four micro watersheds. naranhinna watershed situated in gonangoda, pattiyagama, and gabadagama grama niladari (gn) divisions of deltota divisional secretary division while 95% of micro watershed extent located in gonangoda gn division. as shown in table 1, naranhinna watershed extends 149 ha and elevation ranges between 840 m to 1,520 m above msl, located in the eastern slope of central highlands. keppitiya ela micro watershed with an extent of 203 ha is in three villages namely gurukele, nawa gurukelle and lagumdeniya that located in. gurukele gn division of doluwa divisional secretariat division. nawa gurukelle villages covers major part of the micro watershed. the elevation of keppitiya ela micro watershed ranges between 590-870 m above msl and comparatively large extent of agricultural lands are occupied in the watershed. rajamale micro-watershed is the largest micro watershed extending 206 ha is located in the gurukele and panwilathanna gn divisions of doluwa divisional secretariat division. its elevation ranges between 600-890 m above msl. the smallest micro watershed selected for the study is pambadeniya micro-watershed with area of 83 ha which is located in pambadeniya and panwilathanna gn divisions of doluwa divisional secretariat division and pambadeniya gn division covers 85% of this micro watershed. in addition, baseline survey of the project identified that naranhinna watershed is a part of gurugal oya sub watershed of mahaweli river. keppitiya ela and rajamale micro watersheds are located in the nillamba sub-watershed while pambadeniya micro watershed is located in atabageoya subwatershed of mahaweli river basin. 48 table 1: land use and land cover, and important locational characteristics of four micro watersheds. micro watershed name naranhinna keppetiyaela rajamale pabadeniya, ds division delthota doluwa doluwa doluwa gn divisions gonangoda,pattiyagama gabadagama north gurukelle gurukelle, panvilathenna pabadeniya panvilathenna number of farmers 138 71 307 135 micro watershed extent (ha) 149 203 206 83 agricultural land extent (ha) 48 143 138 59 tea (ha) 33 73 89 30 home garden (ha) 13 11 11 9 mixed crops (ha) 0 57 9 19 paddy (ha) 0 2 1 0 vegetable (ha) 2 0 1 0 abandoned agricultural lands (ha) 64 45 46 8 reservations (ha) 3 7 8 0 forest (ha) 25 1 12 15 pinus plantation (ha) 6 0 0 0 poultry farm (ha) 0 0 26 0 other (cemetery, playground etc.) (ha) 3 6 1 1 1.1 sample collection samples were collected from the outlets of watersheds in three week interval during maha cropping season. three samples/ replicates from each outlets were collected six times from september 2018 to march 2019. sampling points were permanently selected before starting the work and gps locations of selected points were recorded. water samples were collected in clean plastic sampling bottles in the early hours of the day. sampling bottles were previously rinsed with detergent, tap water, and then distilled water. collection of water samples was done by first rinsing the bottles three times with the water taken from watershed outlet before collection. collected water samples were immediately covered, labelled and brought to the lab for analysis. figure 1. geographical locations of four micro watersheds naranhinna, kappetiela, rajamale, and pambadeniya. abeysinghe et al. /journal of tropical forestry and environment vol. 9, no. 02 (2019) 46-54 49 2.3 analysis of water samples the water samples were analysed for ph, ec, tds, nh4 + -n, no-3 -n, available p, total k, na, ca, mg, fe, al, as, cd, pb, and hg. water temperature, ph, ec, tds were measured immediately using the multi-parameter analyser (hatch, sension 156). other parameters such as nh4 + -n, no-3 -n, available p, total k, na, ca, mg, fe, al, as, cd, pb, hg were determined in the laboratory by using standard laboratory methods. nh4 +-n content was determined by uv-visible spectrophotometer with 4500 nh3 f phenate method (solorzano, 1969). no3 n content of water samples were tested by uvvisible spectrophotometer with salicylic acid method (cataldo et al., 1975). available p content of water samples was determined by uv-visible spectrophotometer with ascorbic acid method (olsen et al., 1954). total k, na, ca, mg, fe, al, as, cd and pb contents were measured by icp-oes following the method of martin et al. (1994). in addition, sodium percentage (sp), sodium adsorption ratio (sar) and residual sodium carbonate (rsc), kelly’s ratio (kr), and magnesium hazard (mh) were calculated to test the suitability of water especially for irrigation. sodium percentage (na %) was calculated using the following formula. all ionic concentrations in the equation 1 are expressed in meq/l. na (%) = ( na + + k + ca 2+ +mg 2+ +k + ) ×100 sar was calculated from the ratio of sodium to calcium and magnesium (richards 1954). all ionic concentrations in the equation 2 are expressed in meq/l. sar= na + √ca 2+ +mg 2+ 2 residual sodium carbonate (rsc) index was calculated from the difference of total carbonate and bicarbonate with total calcium and magnesium (ragunath, 1987). all ionic concentrations in the equation 3 are expressed in meq/l. rsc index = [hco3 _ +co3 2 ] [ca 2+ +mg 2+ ] (3) the kelly’s ratio was measured using the expression (kelly, 1963). all ionic concentrations in the equation 4 are expressed in meq/l. kr= na + ca 2+ +mg 2+ the magnesium hazard (mh) was calculated using the equation 5 (szabolcs and darab, 1964). mh= ( mg + ca 2+ +mg 2+ ) ×100 moreover, irrigation water quality index (iwqi) and drinking water quality index (dwqi) were also calculated following the equation 4 (stambuk, 1999). dwqi = σsii n (6) (1) (2) (5) (4) 50 where: n = number of parameters sii = the sub index of n th parameter sii = wi×qi (7) qi = ci si ×100 where: ci = concentration of each chemical parameter in each water sample in mg/l si = drinking water quality standard for each chemical parameter in mg/l wi = wx ∑ wx n i=1 where: wx= relative weight descriptive statistics such as mean, max and min and standard deviation were calculated for the parameters tested for each points and considered them as the water quality status of micro watersheds. 3. results and discussion this chapter first discusses the mean status of the water quality data of the outlet of the four micro watersheds and then compare the tested water quality parameters with the standards of fao irrigation and who drinking water quality. since the comparison of each parameter on the standards doesn’t give overall idea about the suitability of water for irrigation or drinking, this study discusses the overall mean iwqi and dwqi of waters of each micro watersheds also. 3.1 mean status of the water quality of four micro watershed outlets as physical and physicochemical parameters ph, turbidity and electrical conductivity (ec) was tested and their mean values of the six times sampling are shown in table 2. ph of the four watersheds water during maha cropping season ranged from slightly acidic (6.88) to slightly basic (7.14). table 2: variation of physical and physicochemical water quality parameters of four micro-watersheds. watersheds ph turbidity (ntu) electrical conductivity (ec) (µs/cm) naranhinna 7.14 3.95 38.35 kappetiela 6.86 4.88 39.20 rajamale 6.89 5.01 28.11 pambadeniya 6.88 4.56 36.05 who drinking water quality standards 6.5-8.5 5.00 750 fao irrigation water quality standards 6.5-8.5 700 turbidity is a measure of the degree to which the water loses its transparency due to the presence of suspended particle and it shows the relative clarity of the water. mean turbidity of the micro watersheds outlets varied from 3.95 to 5.01 ntu during the maha cropping seasons 2018/19. ec represents the total ionised constitutes of water which is a measure of dissolved salts in water. during the sampling time mean ec was in the ranged from 28.11 to 39.2 µs/cm (table 2) in all micro watersheds. (9) (8) abeysinghe et al. /journal of tropical forestry and environment vol. 9, no. 02 (2019) 46-54 51 the no3-n, nh4-n and po4-p are plant nutrients and their concentration in water indicates eutrophication status of water bodies. the mean no3-n concentrations of four micro watersheds varies from 3.31 to 6.47 in water (table 3) while mean nh4 -n concentration was in the range of 0.42 to 0.75 ppm. table 3: variation of chemical water quality parameters of four micro-watersheds. considering the metal tested, ca was recorded the highest and the lowest was zn (table 4). during the study period, total iron concentration in all four micro watersheds water ranged from 1.23 to1.52 mg/l. pb was observed comparatively higher concentration as a heavy metal and was in the range of 1.94 to 1.46 ppb. as was observed only in naranhinna micro watershed outlet while cr was observed approximately same concentration (0.01 ppm) in all micro watershed outlets. the al concentration of all four micro watersheds varied from 0.00 to 0.05 mg/l (table 4). table 4: variation of metallic water quality parameters of four-micro watershed. naranhinna kappetiela rajamale pambadeniya who drinking water quality standards fao irrigation water quality standards na (ppm) 0.55 0.97 0.7 0.68 200 0-920 mg ( ppm) 1.61 1.34 0.79 1.59 30 0-60.75 ca (ppm) 3.96 3.33 2.04 4.88 75 0-400 cd (ppb) 0.06 0.04 0.04 0.04 3.0 0.01 pb (ppb) 1.46 1.86 1.89 1.94 10 5.0 as (ppb) 4.8 0.0 0.0 0.0 10 0.1 al (ppm) 0.05 0.0 0.01 0.02 0.2 5.0 cr (ppb) 0.01 0.01 0.01 0.01 50 0.1 fe (ppm) 1.23 1.47 1.36 1.52 0.3 5.0 mn ppm) 0.02 0.02 0.02 0.02 0.1 0.2 zn (ppm) 0.0 0.0 0.0 0.0 2.0 2.0 3.2 variation of mean water quality parameters with the fao and who guidelines the ph values recorded in watersheds water were within the standard range of irrigation and drinking water quality standard of fao and who respectively. considering the mean ec, water can be used for drinking and irrigation for any crops without any restriction when compared to who drinking and fao irrigation water quality guidelines. turbidity of water of all most all micro watersheds were within the who permissible level except at the outlet of rajamale watershed (table 2). turbidity was little higher at the rajamale watershed watersheds nh4--n (ppm) no3--n (ppm) po4--p (ppm) hco3 (ppm) co3 -2 (ppm) tds (ppm) naranhinna 0.42 3.74 0.02 129.67 5.83 18.13 kappetiela 0.51 3.31 0.01 90.67 3.33 18.38 rajamale 0.53 6.47 0.01 90.33 6.67 13.15 pambadeniya 0.75 4.40 0.01 120.17 5.83 16.88 who drinking water quality standards 0.5 50 5 200 100 300 fao irrigation water quality standards 0-5 05 0-2 610 0-30 4502000 52 probably due to suspended soil particles by soil erosion at the watershed. fao irrigation water quality standards doesn’t provide a critical level for turbidity. however, high level of turbidity can affect the performance of the irrigation facility, and can lower the hydraulic conductivity of the soil and in turn pollute the soil surface through surface flow. therefore spain recommends a level lower than 10 ntu for vegetables (jeong et al., 2016). however, in terms of turbidity, the water of all micro watersheds during the study period is suitable for irrigation. according to fao guidelines, sensitive crops may be affected by nitrogen (no3-n) concentrations above 5 mg/l (table 3). the highest value of no3-n is recorded at rajamale watershed outlet and long term application of water of rajamale watershed may be affected to nitrogen sensitive crops. this water is however suitable for drinking when compared to who guidelines of no3-n. water status of mean nh4n concentration, water of three watersheds except naranhinna is unsuitable for drinking (table 3). nh4-n is an indicator of the breakdown of organic n (kanownik et al., 2019). hence, organic nitrogen sources of three micro watersheds may be rearing of cattle and the use of organic fertilizers etc., and natural organic matter decomposition. po4-p, hco3 and tds concentrations were with the permissible levels of irrigation and drinking water quality guidelines of fao and who respectively. considering the metal tested, na, mg, ca, mn, al, cr and zn concentration of all the micro watersheds water were with the permissible levels of who and fao guidelines (table 4). the incidence of cognitive impairments, especially in children, and cancers of all sorts are links to toxicants such as hg, pb, as, and cd (obiri et al., 2010). in addition, various studies shows that as, cd are causes for the chronic kidney disease of unknown etiology that prevailed mainly in dry zone area of sri lanka (abeysingha et al., 2018a). however, tested mean concentration of as, cd and pb were within the permissible levels of all four micro watersheds waters during maha cropping season 2018/19. water quality study done by dissanayake and weerasooriya (1986) showed lower concentration of pb (1 to 5 ppb) and cd (1 to 2 ppb) in entire mahaweli water. fe content of water of all micro watersheds exceeded the who drinking water quality limit (0.3 mg/l) of 2004. however, these values did not exceed the concentration for irrigation which is 5 mg/l (fao, 1985). high concentrations of fe are attributable to dissimilarly iron-reduction of fe(iii)-oxide minerals, which is coupled to the oxidation and mineralization of labile organic carbon (borrok et al., 2018). dissanayake and weerasooriya (1986) also observed total fe content in mahaweli river in the range of 0.013 to 4.7 mg/l. the al concentration of all four micro watersheds were with the permissible levels for drinking and irrigation. table 5. variation of derived water quality parameters of four micro-watersheds. watersheds sar rsc sp % kr mh naranhinna 0.18 1.99 28.65 0.25 40.34 kappetiela 0.34 1.88 35.81 0.46 40.00 rajamale 0.29 1.53 43.16 0.70 40.34 pambadeniya 0.25 1.79 12.79 0.36 38.85 suitable limit for irrigation (fao) 18 2.5 60 1 50 sar, rsc, sp%, kr and mh in water samples are generally interpreted for the assessment of the suitability of irrigation water (brindha and kavitha, 2015; abeysingha et al., 2018b). as shown in table 5, average derived water quality parameters of all four micro watersheds were within the permissible critical limit of irrigation water quality of fao. therefore, the water of these four micro watersheds can be used for any crops and soil without detrimental effects. https://www.sciencedirect.com/topics/earth-and-planetary-sciences/oxidation https://www.sciencedirect.com/topics/earth-and-planetary-sciences/mineralization https://www.sciencedirect.com/topics/earth-and-planetary-sciences/organic-carbon abeysinghe et al. /journal of tropical forestry and environment vol. 9, no. 02 (2019) 46-54 53 3.3 water quality indexes drinking and irrigation water quality indexes were calculated using analysed results and standard values of fao and who and results are shown in table 6. according to table 6, the water of all four micro watersheds can be graded as excellent in terms of mean dwqi and it varied from 19.0 to 48.1. the maximum values of dwqi reached 97 at pambadeniya micro watershed which is also good according to the stambuk (1999). considering mean iwqi (8.7-9.2) of tested watersheds, the water can be characterised as excellent for any crops during the study period. however, this analysis did not consider water quality parameters such as micro biological status of water due to limited funding for the study. in addition, high water pollution may be present most frequently during low flow dry season due to lower dilution effect (david et al., 2013). therefore, it is suggested to monitor the water quality status of these four micro watersheds during low rainy, yala cropping season along with the streamflow to further understand entire behavior of these four micro watersheds in relation to water quality. table 6: variation of irrigation and drinking water quality indexes. iwqi dwqi watersheds min max mean min max mean naranhinna 7.9 9.9 8.7 29.2 67.4 48.1 kappetiela 7.8 11.3 9.2 28.0 38.1 34.0 rajamale 7.3 12.6 9.0 11.7 25.9 19.0 pambadeniya 4.5 10.0 7.1 31.5 97.0 45.1 note: 0-50:excellent, 51-100:good, 101-200:poor, 201-300:very poor, >300:unsuitable 2. conclusions the results of this study showed that the most of the tested drinking water quality parameters in all four micro watersheds were within the permissible limits of who standards but fe and nh4 +n concentrations exceed the permissible level. observed fe content of all watersheds was in the range of 1.2-1.5 mg/l. concentration of nh4+ at kappeti ela, rajamale, and pambadeniya was in the range of 0.5 to 0.7 mg/l which exceeded the who standard (0.5 mg/l). however, the water of all four micro watersheds can be graded as excellent in terms of dwqi and it varied from 19 to 48.1. considering mean iwqi (8.7-9.2) of tested watersheds, the water can also be characterized as excellent for any crops during the study period. references abeysingha, n.s., dassanayake, k.b. and weerarathna, c.s., 2018a. will restoration of ecological functions of tank cascade system contribute to reduce ckdu in sri lanka? a review. journal of environment management and sustainable development, 7:60-81. abeysingha, n.s., silva, d.s.m.d. and duminda, d.m.s., 2018b. hydro chemical assessment of agrowell water for irrigation in thalawa block in mahaweli system-h in anuradhapura, sri lanka. the journal of agricultural sciences-sri lanka, 13:186-199. ai l., shi z.h., yin w. and huang x., 2015. spatial and seasonal patterns in stream water contamination across mountainous watersheds: linkage with landscape characteristics. journal of hydrology, 523:398-408. brindha, k. and kavitha, r., 2015. hydrochemical assessment of surface water and groundwater quality along uyyakondan channel, south india. environmental earth science, 73:5383-5393. borrok, d.m., lenz, r.m., jennings, j.e., gentry, m.l., steensma, j. and vinson, d.s., 2018. the origins of high concentrations of iron, sodium, bicarbonate, and arsenic in the lower mississippi river alluvial aquifer. applied geochemistry, 98:383-392. https://www.sciencedirect.com/science/article/pii/s0883292718302993#! https://www.sciencedirect.com/science/article/pii/s0883292718302993#! https://www.sciencedirect.com/science/article/pii/s0883292718302993#! https://www.sciencedirect.com/science/article/pii/s0883292718302993#! 54 charalampous, n., kindou, a., vlastos, d., tsarpali, v., antonopoulou, m., konstantinou, i. and dailianis, s., 2015. a multidisciplinary assessment of river surface water quality in areas heavily influenced by human activities. achieves of environmental contamination and toxicology, 69:208-222. david, a., tournoud, m.g., perrin, j.l., rosain, d., rodier, c., salles, c., bancon-montigny, c. and picot, b., 2013. spatial and temporal trends in water quality in a mediterranean temporary river impacted by sewage effluents. environmental monitoring and assessment, 185:2517-2534. dissanayake, c.b. and weerasooriya, s.v.r., 1986. the environmental chemistry of mahaweli river, sri lanka. international journal of environmental studies, 28:207-223. hewawasam, t., 2010. effect of land use in the upper mahaweli catchment area on erosion, landslides and siltation in hydropower reservoirs of sri lanka. journal of the national science foundation of sri lanka, 38:3-14. jeong, h., kim, h. and jang t., 2016. irrigation water quality standards for indirect wastewater reuse in agriculture: a contribution toward sustainable wastewater reuse in south korea. water, 8:169. kelly, w.p., 1963. use of saline irrigation water, soil science. 95:355-39. kanownik, w., policht-latawiec, a. and fudała, w., 2019. nutrient pollutants in surface water-assessing trends in drinking water resource quality for a regional city in central europe. sustainability mdpi, 11:1-15. martin, t.d., brockhoff, c.a. and creed j.t., 1994. emmc methods work group-method 200.7, determination of metals and trace elements in water and wastes by inductively coupled plasmaatomic emission spectrometry. revision 4.4, u. s. environmental protection agency, cincinnati, ohio. obiri, s., dodoo, d.k., essumang, d.k. and armah, f.a., 2010. cancer and non-cancer risk assessment from exposure to arsenic, copper, and cadmium in borehole, tap, and surface water in the obuasi municipality. ghana, human and ecological risk assessment, 22:651-665. ragunath, h.m., 1987. groundwater. wiley eastern ltd., new delhi. 563. richards, l.a., 1954. diagnosis and improvement of saline and alkali soils. usda handbook, 60. stambuk, g.n., 1999. water quality evaluation by index in dalmatia. water research, 33:3423-3440. szabolcs, i. and darab, c., 1964. the influence of irrigation water of high sodium carbonate content of soils, 2:802-812. singh l.b., 2007. river pollution. 1st ed., aph publishing, new delhi. 192. withanachchi, s.s., köpke, s., withanachchi, c.r., pathiranage, r. and ploeger a., 2014. water resource management in dry zonal paddy cultivation in mahaweli river basin, sri lanka: an analysis of spatial and temporal climate change impacts and tradit ional knowledge. climate, 2:329-354. microsoft word 2 development_of_a_macroinvertebrate-based_index_ref_-_amended-13-03-2012_-_copy.doc perera et al., /journal of tropical forestry and environment vol. 2, no. 01 (2012) 10-19 10 development of a macroinvertebrate–based index of biotic integrity (mibi) for colombo-sri jayewardenepura canal system l. g. r. y. perera 1 *, j. wattavidanage 1 , and n. nilakarawasam 1 1 department of zoology, open university of sri lanka, nawala, nugegoda, sri lanka date received: 10-06-2011 date accepted: 22-02-2012 abstract macroinvertebrates have been identified as excellent indicators of stream/ wetland health as they respond rapidly to environmental changes and provide short to medium term pollution history records. current study was aimed to develop a macroinvertebrate-based index of biotic integrity (m-ibi) which is a new approach to monitor stream/wetland health of colombo-sri jayewardenepura canal system. sixty eight macroinvertebrate samples were obtained using a d-framed kick net from ten stations namely kotte, nawala, ousl, kirimandala mw., wellawatta, orugodawatta, st. sebastian, beira lake, buthgamuwa and royal park representing main branches of the system and marshes covering dissimilar environmental conditions of the canal system during the period of nov. 2008 to june 2009 on monthly basis. habitat characteristics and some water quality parameters also recorded. for the index development, those ten stations were grouped into two as ’reference’ and ‘degraded’ based on their environmental conditions. then ten candidate metrics were selected out of 41 for m-ibi development after evaluating their sensitivity and appropriateness. validity of the index was tested with a new independent data set. scores acquired were positively correlated with do values (r = 0.578). that concluded the potential of using m-ibi developed for biological monitoring and improving biotic integrity of streams/ wetlands. keywords: macroinvertebrates, stream health, biotic integrity, multimetric index, colombo-sri jayewardenepura canal system 1. introduction the canal system which is in and around colombo-sri jayewardenepura area is currently in such an environmentally deteriorated condition due to rapid development and urbanization of the area. the quality of water and habitat in most of the areas are influenced by industrial and public effluent discharge to the canal system. according to the beira lake restoration study (1993) cited by fernando (1994), the data collected by the central environmental authority during a period of 23 months (from march 1991 to february 1993) has shown that st. sebastian canal, which is a branch of the colombo canal system, had recorded high turbidity, bod and cod values, richer in nutrients; reduction of nitrate into nitrite and ammonia (due to eutrophication), high concentrations of metals and faecal coliform. * correspondence: ousl.ruvini@gmail.com tel-++ 94 77236 8009 issn 2235-9370 print / issn 2235-9362 online ©2012 university of sri jayewardenepura perera et al., /journal of tropical forestry and environment vol. 2, no. 01 (2012) 10-19 11 these records have already shown an unhealthy condition of the canal system for living beings. also it has been severely affected on well being of the community live around the canal system. aquatic macroinvertebrates are organisms that are large enough to be seen with the naked eye, lack of a backbone and inhibit all types of waters including lentic, lotic and muddy habitats (viklund, 2011). they are capable of indicating any change in the environment through their responses at different levels of organization, ranging from the individual animal to the total invertebrate community (hodkinson and jackson, 2005). since they live in the water for all or most of their life cycle, are exposed directly to the stress of pollution and the prevailing conditions of the aquatic environment, are easy to collect, differ in their tolerance to amount and types of pollution, are easy to identify, often live for more than one year thus well suited to long-term observation of stresses. their high species diversity which means many potentially different reactions to many different environmental effects can be used as bioindicators for assessing and monitoring the state of health of aquatic environments (invertebrates as indicators, 2008). the biological integrity of a stream or an aquatic ecosystem means how well the habitat can support biological communities, including algae, invertebrates, fish, aquatic mammals and birds. for a given habitat, to have high biological integrity, it should be unimpaired or minimally disturbed by human or other activities and must contain a diverse assemblage of naturally occurring plants and animals (jensen, 2007). multimetric indices are commonly used for evaluating the biological condition of water bodies. most multimetric indices consist of a number of measures or metrics (attributes), describing a specific assemblage like fish or macroinvertebrates, which are combined into a single ‘multimetric’ value representing the condition of a water body (blocksom, 2003). these metrics can represent a wide range of ecological characteristics, including taxa richness, taxonomic composition, pollution tolerance, functional feeding groups, and behavioural habits. the indices of biotic/biological integrity (ibi) are one form of multimetric index that focuses on fish, periphyton, or benthic communities. these ibis are region-specific due to the variations in communities across a wide range of ecological habitats. therefore it is only applicable only for regions that show same environmental conditions (wittman and mundahl, 2002). this study was aimed to develop a macroinvertebrate-based multimetric index of biological integrity as an alternative for other conventional methods like chemical and instrumental which are much expensive and need advance laboratory facilities. 2. methodology 2.1. study area colombo-sri jayewardenepura (diyawanna oya) canal net work is a man made canal system which is located on the left bank of the lower valley of kelani ganga. it is situated in the western province, colombo district of sri lanka, latitudes 6 52’ 55” 6 55’ 45” n and longitudes 79 52’ 35” 79 55’ 15” e. main catchment areas of the canal system are the low-lying marshlands known as kolonnawa, heen ela and kotte marsh (figure 1). these are also important as major flood detention zones in the city of colombo (colombo flood detention areas, 1995). total area of the marsh is around 400ha. the canal system has 3 outfalls to the sea namely mutwal (underground tunnel system), wellawatta and dehiwala (last two are open drains). the average depth of these canals is about 1.5 meters. it may vary seasonally due to heavy sedimentation of silts and bank erosion in the rainy season and it was frequently clogged with floating weeds & dumps (polythene, plastics & domestic wastes). it has been found that 43.5% of the families in the study area dump their household garbage into the marsh (colombo flood detention areas, 1995). present study was carried out covering an extensive area of the canal network. ten sites were selected considering human factors (such as density of settlements, perera et al., /journal of tropical forestry and environment vol. 2, no. 01 (2012) 10-19 12 industries, etc.), habitat characteristics (such as availability of marshlands and riparian vegetation) and representing significant canals and streams. figure 1: study area map: colombo sri jayewardenepura canal system 2.2. data collection biological sampling and habitat assessments were made in ten sampling sites on monthly basis during the period of november 2008 to june 2009. after developing the index a new set of samples was obtained for validation test during the period of may to june 2011. it was included with 3 new sites. macroinvertebrates were sampled using a d-framed kick net with a 400 µm mesh bag. it was dragged along both river banks within a known distance (10 meters). collected macroinvertebrate samples were sorted and identified at least up to family level by using naked eye, a hand lens or microscope and according to both locally and internationally reputed keys and guides such as mendis and fernando (1962), fernando, (1963, 1964, and 1969), the waterwatch australia steering committee (2004) and bartlett (2009), then enumerated and computerized. some of the physical and-chemical parameters like temperature, ph value, conductivity and total dissolved solids (tds) of the water were measured at the field using potable measuring instrument [electrical conductivity metre (340-set1, wtw co., weilheim, germany)]. for further water quality analysis, additional water samples were collected and brought into the laboratory. then, other physical and chemical parameters were analyzed in the laboratory as mentioned below; dissolved oxygen (do): winkler method, biochemical oxygen demand (bod): standard5-day bod testing method, alkalinity and cl concentration: titrimetric. 2.3. data analysis following steps were used to analyse data collected to develop the macroinvertebrate-based index of biotic integrity (m-ibi). step 1. identification of reference and degraded sites (sampling stations): reference and degraded sites were identified and designated based on selection criteria (table 1) that comprise both laboratory and field survey records (do value, bod value, urban land and forested land use practices of the area). 1 4 2 6 3 5 7 8 109 v1 v2v3 n marshlands paddy fields study area flow direction main canals sampling sites: 1. kotte 2. nawala 3. ousl 4. kirimandala mw. 5. wellawatta 6. orugodawatta 7. st. sebastian 8. beira lake 9. budhgamuwa 10. royal park extra sites used for validation: v1. torrington v2. kotte lake v3. kotte bridge map of sri lanka perera et al., /journal of tropical forestry and environment vol. 2, no. 01 (2012) 10-19 13 table 1: criteria used for designating reference and degraded sampling sites reference site degraded site reference do value >= 2.5 urban land use <= 50% forested/marshy land use > 25% bod value < 5mg/l do value < 2.5 urban land use > 50% forested/ marshy land use < 25% bod value >= 5mg/l (stribling et al., 1998) (stribling et al., 1998) (stribling et al., 1998) (chauhan et al., 2011) step 2. compiling and calculating candidate metrics: candidate metrics for testing and potential inclusion in the m-ibi were nominated primarily by assessing the previous work done, parallel studies or documents/ protocols/ guidelines published by varies authors or institutes such as stribling (1998), chirhart (2003), macroinvertebrates as bio-indicators (2008), jensen (2007), calculating and interpreting the genus-level b-ibi (2001), bennett and rysavy (2003), wittman and mundahl (2002), weigel et al. (2002), mandaville (2002) and karr et al. (2002). these macroinvertebrate based 41 candidate metrics were grouped in to five and listed out with their possible response to environmental stresses (stream impairment) in table 2. table 2: candidate metrics and their predicted response to increasing stressors candidate metric predicted response 1. taxonomic richness (i). overall species richness decrease (ii). tot no of individuals of the sample (average ) decrease (iii). tot ept (ephemeroptera+plecoptera+tricoptera) decrease (iv). no of diptera taxa decrease (v). no of molluscs taxa decrease (vi). no of odonata taxa decrease (vii). no of hemiptera taxa decrease (viii). no of coleoptera taxa decrease (ix). no of annelida/policheata taxa decrease (x). no of crustacea taxa decrease (xi). no of chironomidae taxa decrease 2. taxonomic composition & abundance (xii). % of diptera increase (xiii). % of ept decrease (xiv). % of molluscs decrease (xv). % of odonata decrease (xvi). % of hemiptera decrease (xvii). % of coleoptera decrease (xviii). % of annelid/ polycheats decrease (xix). % of crustacen decrease (xx). % of chironomids increase (xxi). most abundant species and % decrease table 2 continues … perera et al., /journal of tropical forestry and environment vol. 2, no. 01 (2012) 10-19 14 3. pollution tolerance / intolerance (xxii) hilsenhoff family biotic index (fbi) increase (xxiii) no of intolerant taxa decrease (xxiv) no of intolerant individuals decrease (xxv) % intolerant ind of the sample decrease (xxvi) no of tolerant taxa increase (xxvii) no of tolerant individuals increase (xxviii) % tolerant ind of the sample increase 4. trophic structure (functional feeding groups) (xxix) no of predator taxa decrease (xxx) no of collector gatherer taxa variable (xxxi) no of collector filter taxa variable (xxxii) no of scraper taxa decrease (xxxiii) no of shredder taxa decrease (xxxiv) % predator individuals decrease (xxxv) % collector gatherer individuals decrease (xxxvi) % collector filter individuals decrease (xxxvii) % scraper individuals decrease (xxxviii) % shredder individuals decrease 5. incorporated diversity (xxxix) shannon-wiener diversity index (h) decrease (xxxl) simpson's diversity index (1-d) decrease 6. proportional metrics (xxxli) heterogeneity decrease step 3. selecting candidate metrics: the criterion used for the selection of candidate metrics was based on; 1. their sensitivity to stream impairment/ human influences: each candidate metrics was tested to determine its correlation with environmental parameters such as do, cl , tds and conductivity by using pearson’s product-moment correlation method. metrics showed significant correlation (r >= 0.5 / -0.5) with those environment parameters were considered further. 2. their ability to distinguish between reference and degraded sites: the distributions of metric values of reference and degraded sites were compared using a non parametric statistical test (t test). metrics whose values differed between reference and degraded sites (p < 0.05) were retained for further analysis, whereas those metrics having similar medians and distributions in reference and degraded sites were eliminated. 3. their contribution of non-redundant information to the m-ibi: many metrics are sensitive to the same change in conditions of stream habitat. these metrics that are highly correlated with one another do not contribute much new information to the m-ibi score (stribling, 1998). hence the redundancies among these metrics were calculated using pearson’s product-movement correlation method. redundant metrics (r >= 0.75) were used in index combinations only if inclusion increased the index classification efficiency. perera et al., /journal of tropical forestry and environment vol. 2, no. 01 (2012) 10-19 15 step 4. index development and scoring: finalized metrics for the index development were further taken into consideration and the calculated metric values were converted to metric scores. quartile statistics for each of the final metrics were calculated for both reference and degraded data sets. metric values that are equal or above 25 th percentile of reference sites were scored as 5 while metric values equal or lower than 25th percentile of degraded sites were scored as 0 and those were in between these two boundaries were scored as 3. to obtain the final m-ibi for a given site, scores obtained for all metrics simply added together. metrics those expectations were reversed were scored conversely. finally the qualitative ratings and the stream condition that describe the status of the canal assessed were developed for five rating categories as excellent, good, fair, poor and very poor by dividing the total index score into five equal classes. step 5. m-ibi testing and validation: once the m-ibi was developed it was tested using a new independent data set of macroinvertebrates collected from ten sites of colombo-sri jayawardhanpura canal system during the period of april-may, 2011. apart from seven sampling stations used for index development there were three (3) new sampling sites namely, torrington, kotte lake (near renovation site) and kotte bridge (near lion’s club). also to test the validity and to check if any relationship existed between the m-ibi and habitat parameters used in conventional monitoring, m-ibi scores were plotted against habitat parameters (do value) for all ten sites. 3. results and discussion 3.1. habitat assessment and designation of sampling stations based on the criteria developed for designating reference and degraded sites; kotte, nawala, ousl, buthgamuawa and royal park sites were declared as reference sites whereas the others were as degraded sites. evaluation criteria and the scores obtained for sites are given in table 3. table 3: evaluation and designation of sampling stations base on their do, bod values, urban land use and forested land use practices of the surrounding area sampling station do value > 2.5 bod value < 5mg/l urban land use < 50% forested land use > 25% total score category (reference>=3/ degraded <3) kotte 1 1 1 1 4 reference nawala 1 1 0 1 3 reference ousl 1 1 0 1 3 reference kirimandala mw 0 1 0 1 2 degraded wellawatta 0 1 0 0 1 degraded orugodawatta 0 1 0 0 1 degraded st. sebastian 0 1 0 0 1 degraded beira lake 0 0 0 0 0 degraded buthgamuwa 1 1 1 1 4 reference royal park 1 1 1 1 4 reference 3.2. metric selection and evaluation results for the first step of metrics evaluation was obtained by finding the correlation between 41 candidate metrics and do, cl-, tds and conductivity values, also between reference and degraded sites. thirty one candidate metrics resulted pearson’s correlation coefficient value as (r) >=0.50 or -0.50 and got the conclusion as ‘positive’. as for the second step, again a ttest was done for all candidate metrics and out of them 11 metrics resulted as ‘positive’. collectively, fifteen candidate metrics representing five main categories (ecological characteristics) were qualified for the next step which was perera et al., /journal of tropical forestry and environment vol. 2, no. 01 (2012) 10-19 16 for the redundancy. after considering the redundancy test results, ten metrics that had less occurrence of obtaining redundancy value (r) >= 0.75 were considered for the index development. however candidate metrics like; (i) overall species richness, (x) no of crustacean taxa, (xxx) shannon-wiener index and (xxxli) heterogeneity were included to the final list as to increase the classification efficiency. 3.3. index development and scoring as the final outcome, ten (10) out of forty one (41) candidate metrics were designated for the mibi development. then their values were converted to unitless m-ibi scores as in table 4. table 4: scoring criteria for the ten metrics used in macroinvertebrates based index of biological integrity (m-ibi) finally, the status or the narrative ratings of the m-ibi and their score were classed into five ranges (rating categories) as excellent, good, fair, poor and very poor as given in table 05. table 5: m-ibi score ranges and corresponding narrative ratings 3.4. m-ibi testing and validation m-imi scores and stream conditions obtained from the validation test done with the independent data set (ten sites) are shown in table 06. the m-ibi scores ranged from 17 to 40 for the tested sites. according to the test results, none of the sites were ranked as ‘excellent’. site named as royal park was ranked as ‘good’ while others were ‘fair’ for 6 sites (nawala, ousl bridge, kirimandala mw., torrington, kotte lake & buthdamuwa), ‘poor’ for the sites called senanayake ground (kotte) and kotte bridge, and “very poor” for wellawatta. these m-ibi scores were positively correlated (r = 0.578) with habitat parameter (do values) recorded from same tested sites. additional tests are needed to be conducted with more sites for further improvements. metrics predicted response to increasing stressors m-ibi score 5 3 1 overall species richness decrease >14.67 14.67 6.67 <6.67 no of hemiptera taxa decrease >1.75 1.75 0.00 <0.00 no of coleoptera taxa decrease >2.67 2.67 0.00 <0.00 no of crustacea taxa decrease >2.25 2.25 0.25 <0.25 % of diptera increase <2.33% 2.33 51.79% >51.79% % of odonata decrease >2.04% 2.04 0.52% <0.52% no of intolerant taxa decrease >1.25 1.25 0.50 <0.50 no of collector gatherer taxa decrease >5.50 5.50 2.67 <2.67 shannon-wiener diversity index (h) decrease >1.95 1.95 1.59 <1.59 heterogeneity increase <67.44% 67.44 87.77% > 87.77% m-ibi score stream condition (narrative rating) 50 – 46 excellent 38 – 45 good 28 – 37 fair 18 – 27 poor 10 – 17 very poor perera et al., /journal of tropical forestry and environment vol. 2, no. 01 (2012) 10-19 17 table 06: m-ibi scores and narrative rating (stream condition) of ten tested sites tag no site location canal name m-ibi score stream condition (narrative rating) 1 senanayake lane kotte canal 20 poor 2 nawala road kotte canal 30 fair 3 narahenpita rd ousl bridge kotte canal 36 fair 4 kirimandala mawatha heen ela (canal) 32 fair 5 near st peter's college wellawatta canal 17 very poor 6 heen marsh torington canal 28 fair 7 wetland restoration site kotte lake 28 fair 8 kotte bridge near lion's club kotte canal 18 poor 9 buthgamuwa kolonnawa marsh kolonnawa canal 36 fair 10 heen marsh near royal park heen ela (canal) 40 good figure 2: overview of the stream condition from the scores obtained for ten sites tested 4. conclusion the m-ibi has shown the potential of using it for biomonitoring and improving biotic integrity of streams/ wetlands. excluding monitoring the health of a natural freshwater ecosystem, m-ibi can be used for monitoring the progress of restored or constructed ecosystems particularly for a renovated wetland like diyawannawa oya. it is ready to be introduced to any government authorities institutes, neighbouring schools, universities, etc. who engaged in stream health monitoring. acknowledgements: authors wish to express their sincere thanks to asian development bank (adb) for providing financial aid, to dean/faculty of natural sciences, the open university of sri lanka (ousl), to all academic and non-academic staff of the department of zoology, ousl and also to the admin staff and the field crew of research & development division, sllrdc for their immense support given to make this effort a success. perera et al., /journal of tropical forestry and environment vol. 2, no. 01 (2012) 10-19 18 references bartlett, t., 2009. bugguide.net [online]. hosted by iowa state university entomology. available from: http://bugguide.net/ [last accessed 30th may,2011]. bennett, s. and kieran rysavy, 2003. a benthic invertebrate index of biological integrity for stream in the bulkley tsa (filed session 2002). biologic consulting terrace, bc. blocksom, k.a., 2003. a performance comparison of metric scoring methods for a multimetric index for mix-atlantic highlands streams. environmental management vol. 31, no. 5.pp. 670-682. calculating and interpreting the genus-level b-ibi, 2001. adapted from: http://www.cbr.washington.edu/salmonweb/ [accessed 1 september 2010]. chauhan, a., chauhan,s., singh,a. p., chamoli,n. and pande, k.k., 2011. evaluation of garhwal springs water for drinking purpose by using water quality index. nature and science; 9(1):8084. [online] http://www.sciencepub.net/nature. chirhart, j., 2003. development of a macroinvertebrate index of biological integrity (mibi) for rivers and streams of the st. croix river basin in minnesota. minnesota pollution control agency, biological monitoring program. colombo flood detention areas, 1995. wetland sites report. central environmental authority. wetland conservation project , sri lanka. fernando, c.h., 1963. a guide to the freshwater fauna of ceylon. supplement 1, in: c. h. fernando. freshwater fauna and fisheries of sri lanka natural resources, energy & science authority. 163172 p fernando, c.h., 1964. a guide to the freshwater fauna of ceylon. supplement 2, in: c. h. fernando. freshwater fauna and fisheries of sri lanka natural resources, energy & science authority. 173207 p fernando, c.h., 1969. a guide to the freshwater fauna of ceylon. supplement 3, in: c. h. fernando. freshwater fauna and fisheries of sri lanka natural resources, energy & science authority. 209275 p fernando, m. s., 1994. sanitary aspects of canal project. 20th wedc conference: colombo, sri lanka. available from: http://info.lboro.ac.uk/departments/cv/wedc/papers/ .html [accessed on 10 feb,2010]. hodkinson, i.d., and jackson, j.k., 2005. terrestrial and aquatic invertebrates as bioindicators for environmental monitoring, with particular reference to mountain ecosystems. environmental management vol. 35, no. 5, pp. 649–666. invertebrates as indicators, 2008. indicator species, biological indicators of watershed health, available from: usepa, http://www.epa.gov/bioindicators/html/invertebrate.html [accessed on 5th feb,2008]. jensen, v., 2007. the biological integrity of okanagan streams: using benthic invertebrates to monitor stream health in the okanagan. environmental protection program, ministry of environment, penticton, bc. karr, j. r., et al., 2002. biological integrity and the index of biological integrity. salamon web. available from: http://www.cbr.woshington.edu/salamonweb/bibi/ [accessed 31 march 2010]. mandaville, s.m., 2002. benthic macroinvertebrates in freshwaters – taxa tolerance values, metrics and protocols. (project h-1), soil & water conservation society of metro halifax. available from: http://chebucto.ca/science/swcs/swcs.html [accessed on 12th feb,2008]. mendis, a. s. & c. h. fernando. 1962. a guide to the freshwater fauna of ceylon. bulletin of the fisheries research station ceylon 12, in: c. h. fernando. freshwater fauna and fisheries of sri lanka natural resources, energy & science authority. 1-160 p. stribling, j.b., benjamin k. jessup and jeffrey s. white, 1998. development of a benthic index of biotic integrity for maryland streams. report no. cbwp-ea-98-3. tetra tech, inc. owings mills, perera et al., /journal of tropical forestry and environment vol. 2, no. 01 (2012) 10-19 19 md 21117 and daniel boward & marty hurd, maryland department of natural resources, monitoring and non-tidal assessment division, annapolis, md. viklund, a., 2011. aquatic macroinvertebrates [online]. krisweb. available from: http://www.krisweb.com/aqualife/insect.htm [ accessed 28 june 2011] weigel, b.m., l.j. henne and luis m. martinez-rivera, 2002. macroinvertebrate-based index of biotic integrity for protection of streams in west-central mexico. journal of north american benthological society, 21(4) : 686-700. wittman, e. and mundahl. n., 2002. development and validation of a benthic index of biotic integrity (b-ibi) for streams in southern minnesota. winona state university, winona, mn 55987. adeleke and moshood /journal of tropical forestry and environment vol 12, no.02 (2022) pg 33-43 correspondence: moshoodfarhan@gmail.com issn 2235-9362 online ©2022 university of sri jayewardenepura 33 impact of urbanization on land cover changes and land surface temperature in iseyin local government area, oyo state, nigeria adeleke s.o.1, moshood f.j.2,* 1 department of surveying and geo-informatics, university of lagos, nigeria 2 department of forest production and products, university of ibadan, nigeria *moshoodfarhan@gmail.com date received: december 05, 2022 date accepted: december 30, 2022 abstract urbanization, without any iota of doubt, is one of the leading factors modifying the earth’s surface because it has a significant impact on land cover changes and land surface temperature (lst). this study assessed the impact of urbanization on land cover changes and lst in iseyin local government area. landsat images of 22 years duration (2000, 2013, and 2022) and 30 m resolution were used in the study. the result showed that in 2000, vegetation occupied 58538 ha (43%), the built-up areas covered 2535 ha (2%), farmland covered 61248 ha (45%), rocky/hilly areas accounted for 3226 ha (2.4%), water bodies accounted for 431.17 ha (0.3%) while bare land covered 8642 equivalent to 6.42% of the area. in 2013, the built-up area occupied 3.4% (4577 ha), water body covered 0.21% (281 ha), vegetation covere d 35% (48136 ha), farmland covered 48% (64352 ha), bare land covered 11% (15944 ha) while rocky/hilly area covered 1.02% (1376 ha). in 2022, built-up areas covered 6393 ha (4.8%), water bodies, vegetation and farmland covered 515 ha, 33819 ha, and 75999 ha respectively while bare land and rocky/hilly areas also covered 14346 ha and 3594 ha respectively. the lst result showed a mean temperature value of about 32oc, 27oc and 29oc in 2000, 2013, and 2022 respectively. the study concludes that urbanization has largely affected the land cover types in iseyin lga and increased the lst between 2000 and 2022. the study has therefore provided a scientific reference to policymakers to develop effective and sustainable policies in iseyin lga. keywords: urbanization, land cover changes, iseyin, land surface temperature, landsat images 1. introduction according to the united nations (2018), about 68% of the human population will be living in urban areas by 2050 due to urbanization. this will affect the land cover and land surface temperature. the need to develop infrastructures that will curb the giant needs of the populace leads to rapid changes in vegetation, water and soils will be replaced with artificial structures such as buildings, roads, and other erections (fortuniak, 2009; gill et al., 2007). through urbanization, natural land covers such as vegetation will be converted to artificial land use types such as residential, recreational, industrial and transportation land uses. these man-made land use types make urban landscapes patchy and complex which will in turn affect the habitability of towns (alberti and marzluff, 2004). the surface temperatures were said to have been increasing globally as a consequence of anthropogenic factors (imhoff et al., 2010; partha et al., 2019). several studies have shown the vital role played by vegetation in the reduction of the impact of urban heating in urban areas (amusa et al., 2022; chen et al., 2013; zhibin et al., 2015). one mailto:moshoodfarhan@gmail.com adeleke and moshood /journal of tropical forestry and environment vol 12,no. 02 (2022) pg 33-43 34 of the effects of urbanization on the environment is what is known as urban heat island (uhi). according to voogt and oke (2003), uhi refers to the difference in surface temperature between rural and urban environments such that the urban environment is wa rmer. this phenomenon occurs because of the structures that absorb and re-emit the sun’s heat. with the rising impact of uhi on human health, it is important to assess the effect of urbanization on land surface temperature (burkart et al., 2011; igun and williams, 2018). like other developing climes, there has been rapid urbanization in iseyin local government area recently. in 2005, the estimated population according to the united nations was approximately 236,000 (oyewole, 2021). although there is no recent census in nigeria to support the recent population in iseyin lga, visual observation and satellite images have shown that the population has increased beyond what it used to be. it is believed that urbanization impacts land cover changes and land surface temperature. this work, therefore, studied the impact of urbanization on land cover changes and land surface temperature in iseyin lga between 2000 and 2022. 2. materials and methods 2.1 study area the study was carried out in iseyin lga of oyo state, nigeria (figure 1). iseyin is one of the lgas that constitutes what is known as oke-ogun region of oyo state (adeyemo, 2016). it is geographically situated on latitudes 3o1'0" e and 7o50'0" n and longitudes 3o1'0" and 3o40'0" n and covers an area of about 134, 668 ha. it is bounded in the north by itesiwaju lga, in the south by ibarapa east lga, in the west by kajola lga, and in the east by oyo west and afijio lgas (ikemenanwa et al., 2020). it has an average annual rainfall of about 1149 mm, a mean relative humidity of about 72% annually, and an annual mean temperature of 24.4 °c (obi-egbedi et al., 2022). adeleke and moshood /journal of tropical forestry and environment vol 12,no. 02 (2022) pg 33-43 35 figure 1: map of iseyin local government area (inset map of nigeria and map of oyo state) 2.2 data acquisition landsat images were downloaded from the united state geological survey (usgs) website using the part and row values (191/055) covering iseyin lga. images with less than 10% cloud cover were downloaded for this study. the characteristics of the images are presented in table 1. all downloaded images fall into approximately the same season. table 1: landsat imagery dataset details year sensor scene id path / row resolution 2000 etm le71910552000037edc00 191 / 055 30m 2013 oli / tirs lc81910552013352lgn01 191 / 055 30m 2022 oli / tirs lc81910552022025lgn00 191 / 055 30m 2.3 image analysis image importing based on the nature of the software used for this research, there is a need for the downloaded images to be converted into a well-recognized format for easy processing, and the importing features of the software helped in executing the conversion process. adeleke and moshood /journal of tropical forestry and environment vol 12,no. 02 (2022) pg 33-43 36 image layer stacking image layer stacking is a pre-process operation to put together all the imported landsat bands converted from tiff to img format. this layer stacking process helps proper band combination for colour visualization before classification. all eleven (11) bands were stacked together for landsat 8 and nine (9) bands for landsat 7. image classification image classification is sorting different pixels into a finite number of individual classes or categories of data based on the data fields. this was achieved using colour differencing. the supervised image classification scheme was employed for this research work. 2.4 trend analysis the land cover changes in the study area were calculated using equation (1). land cover changes = (l2 − l1) (1) 2.5 rate of change rt = {(l2 l1) × 1 𝐿1∗𝑡 } × 100 (2) where: rt = rate of change, l1 (ha) = present year, l2 (ha) = base year and t (year) = periodic interval 2.6 accuracy assessment this process involves ground-truthing which helped in locating the actual features physically and collecting coordinate points reading for each of the desired classification classes and then comparing the collected coordinates to the classified image for accuracy. sensitivity (producer’s accuracy) = 𝑎 𝑎 +𝑐 (3) positive predictive power (user’s accuracy) = 𝑎 𝑎+𝑏 (4) overall accuracy = total number of correct samples total number of samples × 100 (5) kappa coefficient (k) = 𝑁 ∑ 𝑥𝑖𝑖−∑ (𝑥𝑖+𝑋𝑋𝐼 +1 𝑟 𝑖=1 𝑟 𝑖=1 ) 𝑁2−∑ (𝑥𝑖+𝑋𝑋𝐼+1 𝑟 𝑖=1 ) (6) where: a = number of times a classification agreed with the observed value; b = number of times a point was classified as “a” when it was observed to not be “a”; c = number of times a point was not classified as “a” when it was observed to be “a”; d = number of times a point was not classified as “a” when it was not observed to be “a”; r = number of rows and columns in the confusion matrix; n = total number of ground-truthed points (pixels); xii = observation in row i and column i; xi = marginal total of row i, and xi+1 = marginal total of column i. 2.7 normalized difference vegetation index (ndvi) 𝑁𝐷𝑉𝐼 = 𝑁𝐼𝑅 − 𝑅𝐸𝐷 𝑁𝐼𝑅 + 𝑅𝐸𝐷 (7) where: nir = near infrared and red = red band adeleke and moshood /journal of tropical forestry and environment vol 12,no. 02 (2022) pg 33-43 37 2.8 top of atmospheric (toa) spectral radiance 𝑇𝑂𝐴 (𝐿) = 𝑀𝐿 ∗ 𝑄𝑐𝑎𝑙 + 𝐴𝐿 (8) where: ml = band-specific multiplicative rescaling factor; qcal = corresponds to band 10 and al = band-specific additive rescaling factor (isa et al., 2016) 2.9 top of atmospheric to brightness temperature conversion 𝐵𝑇 = ( 𝐾2 1 (𝑙𝑛 ( 𝐾1 1 𝐿) + 1)) − 273.15 (9) where: k1 = band-specific thermal conversion and k2 = band-specific thermal conversion constant (srivastava et al., 2022) 2.10 land surface emissivity (lse) e = 0.004 × 𝑃𝑉 + 0.986 (10) where: e = land surface emissivity and 0.986 correspond to a correction value of the equation (isa et al., 2016). 2.11 proportion of vegetation pv = ( 𝑁𝐷𝑉𝐼−𝑁𝐷𝑉𝐼 𝑚𝑖𝑛 𝑁𝐷𝑉𝐼 max − 𝑁𝐷𝑉𝐼 𝑚𝑖𝑛 ) 2 (11) where: pv = proportion of vegetation, ndvi = dn values from ndvi image, ndvi min = minimum dn values from ndvi image, and ndvimax = maximum dn values from ndvi image (srivastava et al., 2022). 2.12 land surface temperature (lst) lst = 𝐵𝑇 1 + (λ × bt / c2) × ln (e) (12) where: bt = top of atmosphere brightness temperature (oc), λ = wavelength of emitted radiance, e = land surface emissivity, c2 = h × c / s (1.4388 × 10-2 mk) = 14388mk, h = plank’s constant (1.38 × 10-2js), s = boltzmann constant (1.38 × 10-23jk) and c = velocity of light (2.998 ×108 m/s) (isa et al., 2016). 2.13 land use/ land cover classes the distinct land use/ land cover types in the study area are presented in table 2 table 2: land use/land cover types in the study area land use land cover description built-up this indicates areas covered with houses and other buildings that increase over time vegetation these are areas covered with trees, shrubs, and closed-canopy forests. it also includes plantation of trees and cash crops farm/agric land areas where food or cash crops are grown for agricultural purposes. rocky/hilly area these areas have high relief occupying features such as rocks and hills or sand domes water the water bodies are the areas occupied by river and stream flow bare land areas with open land with no use adeleke and moshood /journal of tropical forestry and environment vol 12,no. 02 (2022) pg 33-43 38 3. results 3.1 spatial extent of land cover between 2000 and 2022 the result of the spatial extent of the different land use types in iseyin local government area is presented in table 3. in 2000, vegetation occupied about 58538 ha (43.50%), the builtup area covered approximately 2535 ha (1.88%), farmland covered 61248 ha (45.48%), rocky/hilly area accounted for 3226 ha (2.40%), water bodies accounted for about 431 ha (0.32%) while bare land covered about 8642 (6.42% of the area). in 2013, the built-up area covered 3.40% (4577 ha), water body covered 0.21% (281 ha), vegetation covered 35.74% (48136 ha), farmland covered 47.79% (64352 ha), bare land covered 11.84% (15944 ha) while rocky/hilly area covered 1.02% (1376 ha). in 2022, built-up areas covered 6393 ha (4.75%), water bodies, vegetation and farmland covered 515 ha, 33819 ha, and 75999 ha respectively, bare land and rocky/hilly areas also covered 14346.0 ha and 3594 ha in the same year (table 3). the land cover changes map is shown in figure 2. table 3: spatial extent of land use types in iseyin local government area lulc 2000 area (ha) area (%) 2013 area (ha) area (%) 2022 area (ha) area (%) built-up 2535.84 1.88 4577.42 3.40 6393.53 4.75 water 431.17 0.32 281.72 0.21 515.28 0.38 vegetation 58583.60 43.50 48136.10 35.74 33819.90 25.11 farm/agric land 61248.60 45.48 64352.30 47.79 75999.30 56.43 bare land 8642.43 6.42 15944.50 11.84 14346.00 10.65 rocky/hilly land 3226.79 2.40 1376.39 1.02 3594.40 2.67 total 134668.43 100.00 134668.43 100.00 134668.41 100.00 3.2 accuracy assessment result the overall accuracy of the classification for 2000, 2013, and 2022 was 91.80%, 94.53%, and 91.02%, respectively. the kappa statistics for 2000, 2013, and 2022 were 0.87, 0.92, and 0.87, respectively. the producer’s accuracy ranged between 42.86% and 72.00% in 2000, 33.33% and 100.00% in 2013, and 78.05% and 91.67% in 2022. the user’s accuracy in 2000 ranged between 75.32% and 88.14%, 88.45% and 100.00% in 2013, and 78.05% and 91.67% in 2022 (table 4). table 4: accuracy assessment for the different land use types in iseyin lga 2000 2013 2022 lulc pa (%) ua (%) pa (%) ua (%) pa (%) ua (%) built-up area 72.00 75.32 100 100 73.33 91.67 vegetation 89.66 88.14 88.00 88.45 87.84 84.42 farm/bare land 91.94 81.43 94.81 90.12 82.05 78.05 adeleke and moshood /journal of tropical forestry and environment vol 12,no. 02 (2022) pg 33-43 39 water bodies 30.80 80.35 33.33 100 rocky/hilly land 42.86 78.50 83.33 100 81.82 90.00 overall accuracy 91.80% 94.53% 91.02% kappa statistics 0.87 0.92 0.87 pa – producer’s accuracy; ua – user’s accuracy figure 2: land use cover map in iseyin lga in 2000, 2013 and 2022 3.2 land surface temperature figure 3 presents the land surface temperature (lst) for iseyin lga in 2000, 2013, and 2022. in 2000, the minimum lst was 25.53 oc, the maximum was 48.93 oc and the mean was 31.74 oc. the lst result for 2013 showed that there was a decrease in temperature. the maximum, minimum, and mean temperatures were 37.13 oc, 22.05 oc, and 27.55 oc respectively. in 2022, the minimum, maximum, and mean temperatures were 24.08 oc, 54.21 oc, and 29.48 oc respectively. the lst map is shown in figure 4. adeleke and moshood /journal of tropical forestry and environment vol 12,no. 02 (2022) pg 33-43 40 figure 3: land surface temperature in iseyin lga in 2000, 2013 and 2022 figure 4: lst map for iseyin lga in 2000, 2013 and 2022 4. discussion the study revealed the effect of urbanization on land cover changes and land surface temperature in the study area. our result showed that built-up increased from 2535.84 ha (1.88%) in 2000 to 6393.53 ha (4.75%) in 2022. it also showed that vegetation decreased from 58583.60 ha (43.50%) in 2000 to 33819.90 ha (25.11%) in 2022. on the other hand, farmland 0 10 20 30 40 50 60 minimum maximum mean l a n d s u rf a c e t e m p e ra tu re ( o c ) 2000 2013 2022 minimum maximum mean adeleke and moshood /journal of tropical forestry and environment vol 12,no. 02 (2022) pg 33-43 41 increased from 45.48% to 56.43% in 2022. the rapid urban development in iseyin lga resulted in the expansion of buildings and the reduction in vegetation. it was necessary to increase the residential building and road networks to cater for the rapid increase in population. farmland also increased in size probably to meet the food demand of the increasing population. this result agrees with mbaya et al. (2019) in gombe metropolis, hussain et al. (2020) in the district of multan, and hussain et al. (2022) in southern punjab, pakistan. although no census was conducted in nigeria from 2007 till 2022, however, the population of iseyin in 2000 was approximately 220,000 while the population in 2022 was over 450,000 based on the projection of the nigerian population commission (npc, 2011). the population increase further corroborates the findings of the study. when the population increases in a community, the construction of houses, roads, and other infrastructure increases which will in turn engender the removal of vegetation and extraction of freshwater from the environment (koko et al., 2021). one of the consequences of urban expansion is the increase in land surface temperature. the maximum temperature recorded in 2000 was 48.93 oc. it however increased to 54.21 oc in 2022. urbanization often increases temperature because the materials used in construction absorb heat compared to the natural environment. le et al. (2021) observed higher lst values in the rapidly urbanized ho chi minh city in vietnam. they noted that lst usually increases when natural environments such as vegetation and water bodies are replaced with nontranspiring surfaces such as metals, stones, and concrete. fonseka et al. (2019) also observed an increase in lst in colombo metropolitan area, sri lanka. another major effect of urbanization is urban heat island (uhi). it has been noted that uhi is caused by the removal of natural vegetation and the increase in infrastructures that trap solar energy during the day and release it in form of heat at night (quattrochi et al., 2000). amusa et al. (2022) studied the effect of tree canopy cover on an urban heat island in ilorin metropolis and concluded that trees are useful in reducing the ambient temperature. vegetation that should rather help absorb surface temperature decreased by 18.39% between 2000 and 2022 in the study area while built-up areas increased by 2.87%. 5. conclusion in this study, the impact of urbanization on land cover changes and lst was assessed in iseyin lga, oyo state, nigeria. the study showed that urbanization has modified the land cover types and increased the lst in the study area. built-up areas and farmlands increased by 2.87% and 10.85% respectively while vegetation was reduced by 18.39% between 2000 and 2022. the study also recorded up to a 5.28 ℃ difference in the maximum temperature recorded between 2000 and 2022. although urbanization is important because of the growing world population. however, the land surface temperature can be managed by incorporating certain features in the urban centers. it is recommended that policymakers should focus on planting trees in every urban centre to help absorb heat and reduce the ambient temperature. references adeyemo, o.o. 2016. operational performance of ikere-gorge dam in iseyin local government area of oyo state, south-western nigeria. international journal of advanced academic research 2(8), 8: 19-28. alberti, m. and marzluff, j. 2004. ecological resilience in urban ecosystems: linking urban patterns to ecological and human function. urban ecosystem 7: 241-265 adeleke and moshood /journal of tropical forestry and environment vol 12,no. 02 (2022) pg 33-43 42 amiri, r., weng, q., alimohammadi, a. and alavipanah, s.k. 2009. spatial–temporal dynamics of land surface temperature in relation to fractional vegetation cover and land use/cover in the tabriz urban area, iran. remote sensing of environment 113: 2606-2617. amusa, t.o., adebayo, r.a., moshood, f.j. and ibrahim, t.m. 2022. effect of tree canopy cover on urban heat island in ilorin metropolis, kwara state, north-central, nigeria. agriculture and forestry journal 6(2): 86-93. burkart, k., schneider, a., breitner, s., khan, m.h., krämer, a. and endlicher, w. 2011. the effect of atmospheric thermal conditions and urban thermal pollution on all cause and cardiovascular mortality in bangladesh. environmental pollution 159: 2035-2043 chen, d., wang, x., khoo, y.b., thatcher, m., lin, b.b., ren, z. and barnett, g. 2013. assessment of urban heat island and mitigation by urban green coverage. in mitigating climate change (springer berlin heidelberg) pp. 247-257. fonseka, h.p.u., zhang, h., sun, y., su, h., lin, h. and lin, y. 2019. urbanization and its impacts on land surface temperature in colombo metropolitan area, sri lanka, from 1988 to 2016. remote sensing 957(11): 1-19. fortuniak, k. 2009. global environmental change and urban climate in central european cities. international conference on climate change. the environmental and socio-economic response in the southern baltic region, university of szczecin, poland, 25-28 may 2009. conference proceedings. wyd. international baltex secretariat, publication, 42: 65-66. gill, s.e., handley, j.f., ennos, a.r and pauleit, s., 2007. adapting cities for climate change: the role of the green infrastructure. built environment 33(1): 115-133. hussain, s., mubeen, m., ahmad, a., majeed, h., qaisrani, s.a., hammad, h.m., amjad, m., ahmad, i., fahad, s., ahmad, n. and nasim, w. 2022. assessment of land use/land cover changes and its effect on land surface temperature using remote sensing techniques in southern punjab, pakistan. environmental science and pollution research https://doi.org/10.1007/s11356-022-21650-8. hussain, s., mubeen, m., akram, w., ahmad, a., habib-ur-rahman, m., ghafar, a. and nasim, w. 2020. study of land cover/land use changes using rs and gis: a case study of multan district, pakistan. environmental monitoring and assessment 192(1): 2 https://doi.org/10.1007/ s10661-019-7959-1. igun, e. and williams, m. 2018. impact of urban land cover change on land surface temperature. global journal of environmental science and management 4(1): 47-58. ikemenanwa, s.c., olajide o.a. and ajayi, o.e 2020. an assessment of the effects of female participation in cassava: adding value for africa (c: ava) women empowerement project, with iseyin local government area of oyo state, nigeria, as case study. ibadan journal of gender studies 3 and 4: 167-184. imhoff, m.l., zhang, p., wolfe, r.e. and bounoua, l. 2010. remote sensing of the urban heat island effect across biomes in the continental usa. remote sensing of environment 114: 504-513. isa, z., baba, i.i. and ayuba, z. 2016. estimation of land surface temperature of kaduna metropolis, nigeria using landsat images. science world journal 11(3): 36-42. koko, a.f., wu, y., abubakar, g.a., alabsi, a.a.n., hamed, r., bello, m. 2021. thirty years of land use/land cover changes and their impact on urban climate: a study of kano metropolis, nigeria. land 10: 1106. le, t.t.h., nguyen, v.t., pham, t.l., tong, t.h.a., la, p.h. 2021. impacts of urban land cover change on land surface temperature distribution in ho chi minh city, vietnam. journal of the korean society of surveying, geodesy, photogrammetry and cartography 39(2): 113-122. adeleke and moshood /journal of tropical forestry and environment vol 12,no. 02 (2022) pg 33-43 43 mbaya, l.a., abu, g.o., makadi, y.c. and umar, d.m. 2019. effect of urbanization on land use land cover in gombe metropolis. british journal of earth sciences research 7(2): 5361. national population commission (npc) 2011. nigeria national census: population distribution by sex, state, lgas and senatorial districts. abuja, nigeria. nwilo, p.c., olayinka, d.n., obiefuna, j., atagbaza, a.o. and adzandeh, a.e. 2012. determination of land surface temperature (lst) and potential urban heat island effect in parts of lagos state using satellite imageries. futy journal of the environment 7(1): 1933. obi-egbedi, s.o., osanyinlusi, o.i. and adekunle, o.b. 2022. does contract farming really matter in cassava farms productivity in iseyin local government area, oyo state, nigeria? agricultura tropica et subtropica 55: 65-73. oyewole, m.f. 2021. factors influencing instability within rural households in iseyin local government area, oyo state, nigeria. journal of home economics research 28(2): 8495. partha, p.g., vinoj, v., swain, d., roberts, g., dash, j. and tripathy, s. 2019. land use and land cover change effect on surface temperature over eastern india. scientific reports 9: 8859. quattrochi, d., luvall, j., rickman, d., estes, m., layman, c., howell, b. 2000. a decision support information system for urban landscape management using thermal infrared data. photogrammetric engineering and remote sensing 66(10): 1195-1207. sharma, r., ghosh, a., and joshi, p.k. 2013. spatio-temporal footprints of urbanization in surat, the diamond city of india (1990–2009). environmental monitoring and assessment 185: 3313-3325. srivastava, n., saini, s. and shukla, s. 2022. land surface temperature and its correlation with vegetation cover using landsat data: a study of gorakhpur, uttar pradesh. international research journal of engineering and technology 9(4): 810-818. united nations, 2018. 2018 revision of world urbanization. https://www.un.org/development/ desa/en/news/population/2018-revision-of-world-urbanization-prospects.html voogt, j.a., oke, t.r. 2003. thermal remote sensing of urban climates. remote sensing of environment 86: 370-384. world bank, 2010. world development report for 2010. development and climate change. washington d.c: world bank. zhibin, r., haifeng, z., xingyuan, h., dan, z. and xingyang, y. 2015. estimation of the relationship between urban vegetation configuration and land surface temperature with remote sensing. journal of the indian society of remote sensing 43: 89-100. mani and varghese /journal of tropical forestry and environment vol. 11, no. 02 (2019) 67-75 67 characterization of forest fire frequency using fire scar mapping of temporal satellite data for forest fire management jugal kishore mani* and a. o. varghese regional remote sensing centre-central, nrsc, isro, amravati road, nagpur, maharashtra-440033, india date received: 23-08-2021 date accepted: 28-12-2021 abstract one of the most complex problems facing in tropical forests, particularly in deciduous forests, is the recurrent incidence of fire. it is well known that fire caused extensive damage in the forest ecosystem by quantitatively and qualitatively. to reduce occurrences of forest fire, proper management of fire is highly important which entails mapping of forest fire frequency and identification of suitable area for watchtowers. in the present study, fire frequency analysis of melghat tiger reserve, maharashtra was done for the last seven years (2014-2020) based on the fire scar on the temporal landsat data during fire season (january-june). fire frequency analysis shows that an area of 1053.64 ha (0.52%) of the reserve was burned all seven years followed by 3050.53 ha (1.49%) for six times, 3849.52 ha (1.88%) for five times, 5520.04 ha (2.70%) for four times, 11845.63 ha (5.80%) for three times, 36863.52 ha (18.03%) for two times, 70126.33 ha (34.31%) for once and 72093.02 ha (35.27%) remains unburned all these seven years. the fire frequency map generated was used as an input for prioritizing the locations of watch towers as well as prioritizing grazing closure areas and fires lines. identification of suitable sites for locating new watchtowers has been done by integrating and modeling of forest fire frequency map, existing watchtowers and viewshed analysis in gis. based on these results only thirteen watchtowers were categorized under retainable among the existing watchtowers and 27 new watchtowers are proposed to cover the entire area. keywords: fire scar, fire frequency, viewshed analysis, forest fire watchtower, geospatial technology 1. introduction forest fire generally is a natural phenomenon, besides natural fire some forests are also get affected by anthropogenic fires. these fires may prove harmful or beneficial depending on the season or forest type. in india, 21.67% of total geographical area is actually covered with forest land (fsi, 2019). every year large areas of forests are impacted by fires of varying intensity and extent. based on the forest inventory records, 54.40% of forests in india are exposed to occasional fires, 7.49% to moderately frequent fires and 2.40% to high incidence levels while 35.71% of india’s forests have not yet been exposed to fires of any real significance (fsi, 2019). it is well known that fire causes extensive damage in the forest ecosystem by quantitatively as well as qualitatively (bright et al., 2019; reddy et al., 2020; halofsky, 2020). forest fires have environmental impact in terms of tropical biomass burning, which produce large amount of trace gases, aerosol particles, and play a key role in troposphere chemistry and climate anomalies (kannemadugu et al., 2015). precious forest resources, including carbon locked in the biomass, are losing due to forest fires every year (menon et al., 1999; varghese, 1997; juárez-orozco et al., 2017; reddy et al., 2018), which adversely impact the flow of goods and services from forests. indian national working plan code (2014) specify to carry out fire frequency and burnt area mapping for fire vulnerability identification for working plan preparation. *correspondence: correspondence email address: jugalmani@gmail.com tel: 07122851215 © university of sri jayewardenepura 68 satellite based remote sensing technology and geographic information system (gis) tools have been effective in better prevention and management of fires through creation of early warning for fire prone areas, monitoring fires on real time basis and estimation of burnt scars (prasanth et al., 2009; mani and varghese, 2018; axel, 2018). the temporality of the satellite data helps in analyzing the frequency of forest fires of a particular area. the study area, melghat tiger reserve (mtr), covering dry deciduous forest, shed their leaves and spread like a thick carpet on the ground. tall dry grasses and lantana all over the study area make thick cover of dry leaf litter contribute potential fuel for surface fire. this surface fires often occur in melghat forests, which spread very fast to vast areas covering deep valleys and rugged high hills. due to these reasons mapping of fire frequent zones is necessary to classify the areas into different categories and manage it accordingly. a large variation exists between exact area burnt and area reported by ocular method by the forest staff. most of times the area reported are always less than reality, or sometimes they are highly exaggerated. nearly an error of average 17% is present between the ground and reported areas (varghese and suryavanshi, 2017). error is introduced from primary stage as burnt area estimation technique is ocular without surveying in detail. forest department cannot be blamed for faulty estimation of burnt areas. there are no skilled surveyors to draw maps accurately and moreover scientific instruments preset are also very less. this estimated error increases as data goes on secondary sources. this result into decline of significance in the post fire treatment specified for maintenance of burnt area. the use of geospatial technology in forest fire management will result in minimized work and higher accuracy (parajuli et al., 2020). it also aims to prove its utility along with the conventional methods for assisting the forest managers to mitigate forest fires. in the present study attempted to map the fire frequency in mtr forest by fire scar mapping on satellite data during the forest fire season and suitability analysis for location of forest fire watchtowers for fire management. 2. methodology 2.1 the study area melghat tiger reserve (mtr) is situated in the satpura hill ranges of central india. melghat tiger reserve lies in amravati district in vidarbha region of maharashtra, bordering madhya pradesh in the north and east. melghat tiger reserve has a huge area covering 2027 square kilometer which is divided into three divisions for management purpose, i. e. akot, sipna and gugamal divisions (figure 1). figure 1. location map of the melghat tiger reserve with forest density classes mani and varghese /journal of tropical forestry and environment vol. 11, no. 02 (2019) 67-75 69 most of the forest is dry deciduous, consisting of teak and bamboo species along with patches of other species like madhuca latifolia (mahuwa), diospyrous melanoxylon (tendu), etc. lantana has severely invaded majority of the area (varghese and suryavanshi, 2017). the leaves of all these species and grass together acts as catalyst for frequent forest fire. vegetation and climate both are interdependent on one another; climate itself determines the type of vegetation present in the reserve i.e dry deciduous forest. summer is very hot having a maximum temperature of 48˚c and winter is cool with a minimum temperature recorded is 4˚c. good rainfall is received during monsoons which varies from 950 to 1400 mm. average height ranges between 381 m and 1100 m above mean sea level. these hills and valleys have constant abrupt variation in aspect and gradient, about 8 to 10% of the area is steep escarpment. fire usually spreads more quickly up on slope as compared to the down slope. as flames rise up the vegetation present on the upper side gets fire and spreads ahead. 2.2 data used and approach melghat tiger reserve is located in central india, which consists of dry deciduous forest, prone to forest fires. annually, wildfire crops up from 15th february to 15th june in summer months. but in some rare circumstances, november to january is also seen as fire season (varghese and suryavanshi, 2017). forest policy infers that, after each fire, the amount of area that is burnt due to fire has to be estimated, damage caused is calculated and reported to the ministry. based on the area burnt, post fire treatments are carried out. in the present study, january to june have been considered as fire season and these six months landsat satellite series data downloaded from usgs website (https://earthexplorer.usgs.gov/, accessed 16 february 2021) and mosaicked to cover the full extent of the study area. january to june monthly data of 2014 to 2020 have been prepared for the fire season months. forest fire scars are clearly visible on these satellite image and this information was digitized on-screen. to avoid the duplication of fires scar in one fire season, only fire scar map of each year has been generated. so, fire scars of each of the months have been put together and generated the area burned in that particular year. the fire scar map generated for all the seven years were integrated and derived fire frequency map. existing fire watchtowers do not cover the entire area of mtr for monitoring the incidence of fire, so the fire frequency map generated was used as an input for prioritizing the locations for installation of watchtowers. identification of suitable sites for locating new watchtowers has been done by integrating and modelling of forest fire frequency map, existing watchtowers and visibility analysis in gis. there are three main methods of computing visibility analyses i.e., line of sight, viewshed and visibility. here viewshed analysis is used with present and proposed watchtowers as observer points/cell. viewshed is created over a dem using an algorithm that estimates the difference in elevation in the observer’s cell and the target cell. viewshed will analyze an unobstructed view from an observer point (also called a view source) to an object of interest (target) in any direction, where the target is coincident with the ground. the analysis uses the elevation value of each cell of the digital elevation model (dem, https://bhuvan.nrsc.gov.in/, accessed 8 december 2020) to determine visibility to or from a particular cell. radius for the line of sight for each tower was given 10 km with a height of observation of 10 m. 3. results as illustrated in the previous section, year wise fire occurrence maps are generated and utilized for the preparation of fire history or fire frequency map. fire frequency map was generated by adding together individual years fire occurrence data for the last seven years (figure 2). as shown in figure 2, 2016 recorded the highest area burned with 94767.16 ha followed by the year 2015 (47448.80 ha), 2014 (32731.28), 2017 (29556.31), 2020 (22090.68), 2018 (14245.77) and 2019 (6224.76). area wise burned scar are more registered in sipna division and akot is more susceptible to fire with percentage wise of burned area. some areas in mtr are targets for fire due to grazing, non-wood forest produce (nwfp) collection etc., by local people. 70 figure 2. fire frequency map of melaght tiger reserve overlaid on compartment and range boundaries fire frequency map is generated in the scale of 0 to 7 based on the seven years fire history map. frequency seven denotes all seven years that area is burned and 0 denotes there is no fire occurrence. fire frequency map shows that an area of 1053.64 ha (0.52%) of the melghat tiger reserve burned all seven years followed by 3050.53 ha (1.49%) for six times, 3849.52 ha (1.88%) for five times, 5520.04 ha (2.70%) for four times, 11845.63 ha (5.80%) for three times, 36863.52 ha (18.03%) for two times, 70126.33 ha (34.31%) for once and 72093.02 ha (35.27%) remains unburned all these seven years. division wise information on fire frequency shows that percentage of burnt area in high frequency classes is more in akot forest division. gugamal division registered less percentage of area in high frequency classes and nearly 46.01% of area falls under unburned category. in sipna division more area falls under one time burned category (35.78%). frequent fires contribute to the rapid invasion of exotic fire adopted species. species like lantana camara and chromolaena odorata colonize regions where frequent fire occurs (narendran, 2001). a fire watchtower provides housing and protection for the officials whose duty it is to search for wildfires in the wilderness. the fire lookout tower is normally a small structure, usually located on the summit of a mountain or other high vantage point, in order to maximize the viewing distance and range, known as viewshed. the viewshed analysis provided vital information about the viewability of the existing fire watchtowers. viewshed analysis using digital elevation model (dem) is a powerful tool to identify visibility a particular location to its preferred periphery. a visual field or isovist is defined as a visual area that is wholly visible across the system from a defined vantage point (benedikt, 1979). the watchtowers in mtr are categorized into three categories i. e. proposed, removable and retainable based on the visibility and fire frequency (figure 3). mani and varghese /journal of tropical forestry and environment vol. 11, no. 02 (2019) 67-75 71 figure 3. site suitability for forest fire watchtowers in melghat tiger reserve overlaid on dem a total of thirty-three forest fire watchtowers are existing in the tiger reserve. among the existing watchtowers, only thirteen watchtowers were categorized under retainable. the remaining watchtowers were eliminated due to their locations i. e. close to another watchtower, in the valley from where area visibility is very less, located near to villages, unnecessarily present when other watchtowers could cover the same area and considering tourist watchtower as fire watchtower. based on the above criteria’s and its modelling in gis and viewshed analysis as mentioned above, twenty-seven new watchtowers were proposed along with the watchtowers that were to be retained. new watchtowers are proposed at a location having a higher elevation to cover the maximum area as mtr is entirely in hilly terrain. existing watchtowers could not cover newly identified fire prone areas like compartments near chikali, kelpani, dhargad, etc. the retained old watchtowers and newly proposed watchtowers together cover the entire area of melghat tiger reserve without any gap in between. 4. discussion fire frequency can be defined as the sum of times that fires happen within a distinct area and time period. fire frequency is also a mathematical expression of fire incidence or rate, such as the average time interval between successive fires or the number of fires within a specific period of time. it is a generic term referring to general fire occurrence or rate (firewords, 2018). fire frequency is one of the key components of fire regime, together with the pattern and the intensity of wildfires which prevail in a region (pyne et al., 1996). characterizing fire frequency has many implications for fire ecology and for fire risk assessment. most of the studies in forest fire focused on mapping of the extent and severity of forest fire but not much emphasis is made on the management practices that prevent further spread of fires and its control with infrastructure developments. many studies have done by using viewshed analysis for validating the viewable areas for forest fire mitigation (cheng et al., 1998; che-bin and ahuja, 2004) but integrating fire frequency for site suitability analysis of watchtowers is a novel approach in the present study. for the preparation of management plan to 72 mitigate fire annually, year wise fire frequency map is required to be generated (rao et al., 2007). frequency of fire occurrence changes with the change in season and year. hence, indian national working plan code (2014) specify to analyze particulars of the places along with area affected by fire and appropriate measures taken for the last five years for the working plan revision. mainly three methods are used in fire frequency generation from satellite imageries. the first one is by visual interpretation of temporal satellite data as demonstrated here. the second method is based on digital classification of the satellite data through various supervised or unsupervised classifiers. the third method is by using spectral indices (si) with threshold classification technique. various si are developed for the detection of burn scar and fire severity analysis based on the combination of visible, near infrared, and shortwave infrared domains of the electromagnetic spectrum. burn area index (martin et al., 1998), normalized burn ratio (key and benson, 2006), normalized difference moisture index (wilson and sader, 2002), burned area index modified-lswir (martin et al., 2006), burned area index modifiedsswir (martin et al., 2006), mid infrared burn index (trigg and flasse, 2001), tasseled cap brightness, tass cap greenness, tass cap wetness index (crist and cicone, 1884; crist, 1985) and global environmental monitoring index (pinty and verstraete, 1992) are some of commonly used sis. the main disadvantage of using digital or sis based methods is the low classification accuracy. it is very difficult to digitally classify burn scars from other land cover classes especially wet and barren areas. the burn scar analysis demands high classification accuracy because these inputs are using for various management as well as commercial purposes. collection of non-timber forest produce (ntfp) of some of the forest divisions in india are restricted if the burned areas are more than the specified limit. so, the present study outline method for the identification of suitable sites for locating watchtowers by integrating and modeling of forest fire frequency map, existing watchtowers and viewshed analysis in gis. 5. conclusion to formulate the strategy for the forest fire management information, forest fire frequency plays a pivotal role. the present findings documented a methodology to derive fire frequency using fire scar mapping on satellite data considering melghat tiger reserve in maharashtra as a study site. fire frequency analysis was done for the last seven years (2014-2020) based on the fire scar on the temporal landsat satellite series data during the fire season. the fire frequency map generated along with existing forest fire watchtowers and viewshed analysis was used for the identification of suitable sites for installation of watchtowers for monitoring and management of forest fire in mtr. the present findings emphasis that the utility of geospatial technology in forest fire frequency mapping and identification of sites for installation of forest fire watchtowers for an effective forest fire monitoring and management with minimum cost and time. acknowledgment authors extend their sincere gratitude to regional remote sensing centre-central, national remote sensing centre (nrsc), indian space research organisation (isro) and additional pccf, melghat tiger reserve, maharashtra for providing opportunity and facility to conduct the study. the technical support provided by rrsc-central staff is duly acknowledged. we are also thankful to usgs earth explorer maintained by the nasa and bhuvan-indian geo platform maintained by nrsc, isro for online accessibility of landsat data and dem, respectively. authors are also thankful to the anonymous reviewers. references axel, a.c., 2018. burned area mapping of an escaped fire into tropical dry forest in western madagascar using multi-season landsat oli data. remote sensing 10(3), 371-387. https://doi.org/10.3390/rs10030371. mani and varghese /journal of tropical forestry and environment vol. 11, no. 02 (2019) 67-75 73 benedikt, m.l., 1979. to take hold of space: isovists and isovist fields. environment and planning b: planning and design 6(1), 47-65. https://doi.org/10.1068/b060047. bright, b.c., hudak, a.t., kennedy, r.e., braaten, j.d., khalyani, a.h., 2019. examining post-fire vegetation recovery with landsat time series analysis in three western north american forest types. fire ecology 15, 1-14. https://doi.org/10.1186/s42408-018-0021-9. che-bin, l., ahuja, n., 2004. vision based fire detection. pp 134-137 in proceedings of 17th international conference on pattern recognition, 23 august 2004, united states. https://doi.org/10.1109/icpr.2004.1333722. cheng, cuo-pin, shih, tian-yuan., 1998. the variation of viewshed analysis result caused by different implementations. in proceeding of 19th asian conference on remote sensing, 16-20 november 1998, manila. crist, e.p., cicone, r.c., 1984. a physically-based transformation of thematic mapper data-the tm tasseled cap. ieee transactions on geoscience and remote sensing ge-22(3), 256-263. https://doi.org/10.1109/tgrs.1984.350619. crist, e.p., 1985. a tm tasseled cap equivalent transformation for reflectance factor data. remote sensing of environment 17(3), 301-306. https://doi.org/10.1016/0034-4257(85)90102-6. firewords., 2018. glossary of fire science terminology. http://www.firewords.net/. accessed 4 october 2021. fsi., 2019. india state of forest report. https://fsi.nic.in/isfr19/vol2/isfr-2019-vol-ii-west-bengal.pdf. accessed 6 june 2021. halofsky, j.e., peterson, d.l., harvey, b.j., 2020. changing wildfire, changing forests: the effects of climate change on fire regimes and vegetation in the pacific northwest, usa. fire ecology 16(4): 1-26. https://doi.org/10.1186/s42408-019-0062-8. juárez-orozco, s.m., siebe, c., fernández y fernández, d., 2017. causes and effects of forest fires in tropical rainforest: a bibliometric approach. tropical conservation science 10, 1-14. https://doi.org/10.1177 /19400829 17737207. kannemadugu, h.b.s, varghese, a. o., mukkara, s.r., joshi, a.k., moharil, s.v., 2015. discrimination of aerosol types and validation of modis aerosol and water vapour products using sun photometer over central india. aerosol and air quality research 15, 682–693. https://doi.org/10.4209/aaqr.2014.04.0088. key, c.h., benson, n.c., 2006. landscape assessment: ground measure of severity, the composite burn index; and remote sensing of severity, the normalized burn ratio. pp la 1-51 in lutes et al. (eds.) in firemon: fire effects monitoring and inventory system. usda forest service, rocky mountain research station, ogden, ut, usa. mani, j.k., varghese, a.o., 2018. remote sensing and gis in agriculture and forest resource monitoring. pp 377-400 in g. p. obi reddy & s. k. singh (eds.) geospatial technologies in land resources mapping, monitoring and management. springer nature, switzerland. 74 martín, m.p., 1998. cartografía e inventario de incendios forestales en la península ibérica a partir de imágenes noaa-avhrr. doctoral thesis. alcalá de henares, universidad de alcalá. martín, m.p., gómez, i., chuvieco, e., 2006. burnt area index (baim) for burned area discrimination at regional scale using modis data. forest ecology and management 234, s221. https://doi.org/10.1016/j.foreco.2006.08.248. menon, a.r.r., varghese, a.o., martin lowel, k.j., 1999. impact of fire on moist deciduous forest ecosystem of southern tropical forests of india. in impacts of fire and human activities on forest ecosystems in the tropics. pp 52-61 in proceeding of international symposium on asian tropical forest management. 20-23 september 1999, samarinda, indonesia. narendran, k., 2001. forest fires: origins and ecological paradoxes. resonance 6, 34-41. https://doi.org/10.1007/bf02868242. national working plan code – 2014. for sustainable management of forests and biodiversity in india. forest research institute, dehradun. ministry of environment & forests, government of india, new delhi. https://www.forests.tn.gov.in/tnforest/app/webroot/img/document/gov-indiapublication/11.pdf. accessed 1october 2021. parajuli, a., gautam, a.p., sharma, s.p., bhujel, k.b, sharma, g., thapa, p.b., bist, b.s., poudel, s., 2020. forest fire risk mapping using gis and remote sensing in two major landscapes of nepal. geomatics, natural hazards and risk 11(1), 2569-2586. https://doi.org/10.1080/19475705.2020.1853251. pinty, b., verstraete, m.m., 1992. gemi: a non-linear index to monitor global vegetation from satellites. vegetatio 101, 15-20. https://doi.org/10.1007/bf00031911. prasanth, d.k., ashwini, s.p., varghese, a.o., joshi, a.k., 2009. mapping of forest fire risk zones and identification of suitable sites for fire watch towers using remote sensing and gis. pp 17-19 in proceeding of the isrs symposium on advances in geo-spatial technologies with special emphasis on sustainable rainfed agriculture. 17-19 september 2009, nagpur, india. pyne, s.j, andrews, p.l., laven, r.d., 1996. introduction to wildland fire. 2nd edition. new york, ny: john wiley and sons, inc. 769p. rao, m.k., varghese, a.o., krishna murthy, y.v.n., 2007. remote sensing and gis inputs for working plan preparation. indian forester 133 (1a), 65-76. reddy, c.s., satish, k.v., prasada rao, p.v.v., 2018. significant decline of forest fires in nilgiri biosphere reserve, india. remote sensing applications: society and environment 11, 172-185. reddy, c.s., unnikrishnan, a., bird, n.g., faseela, v.s, asra, m., manikandan, t.m., rao, p.v.n., 2020. characterizing vegetation fire dynamics in myanmar and south asian countries. journal of the indian society of remote sensing 48, 1829-1843. https://doi.org/10.1007/s12524-02001205-5. mani and varghese /journal of tropical forestry and environment vol. 11, no. 02 (2019) 67-75 75 trigg, s., flasse, s., 2001. an evaluation of different bi-spectral spaces for discriminating burned shrubsavannah. international journal of remote sensing 22, 2641-2647. https://doi.org/10.1080/01431160110053185. varghese, a.o., suryavanshi, a., 2017. forest cover transformation analysis and management of melghat tiger reserve using remote sensing and gis. technical report no. rrsc-c/nrsc/2017/9. https://doi.org/10.13140/rg.2.2.27068.49280. varghese, a.o., 1997. ecological studies of the forests of peppara wildlife sanctuary using remote sensing techniques. phd thesis, forest research institute, dehradun, pp 286. wilson, e.h., sader, s.a., 2002. detection of forest harvest type using multiple dates of landsat tm imagery. remote sensing of environment 80, 385-396. https://doi.org/10.1016/s00344257(01)00318-2. dey et al. /journal of tropical forestry and environment vol. 11, no. 02 (2021) 37-47 37 *correspondance:somadeyfor32@gmail.com tel: +8801533369754 © university of sri jayewardenepura effect of pre-sowing treatments on germination and initial growth of terminalia citrina: a medicinal tree species in bangladesh s. dey1, m. k. hossain1, r. nandi1, m. saifullah2 1institute of forestry and environmental sciences, university of chittagong, chittagong, bangladesh 2bangladesh agricultural research council, farm gate, dhaka, bangladesh date received: 22-09-2021 date accepted: 28-12-2021 abstract terminalia citrina (gaertn.) roxb. ex. fleming (local name-hatiyal) is an important medicinal tree species naturally grown in sal and hill forests of bangladesh. an experiment was conducted at the institute of forestry and environmental sciences, university of chittagong, bangladesh, to find out the effects of pre-sowing treatments on germination and vigor seedling production capability. seeds were treated with six pre-sowing treatments, e.g. t0-seeds without any treatment (control), t1-seeds soaking in normal water for 24 hours and sown in polybags (24º c), t2-seeds soaking in normal water for 48 hours and sown in polybags (24º c), t3-fruits sown in seedbed, t4-seeds soaking in hot water for 1 minute and sown in propagator house (80º c), and t5-seeds sown in propagator house. highest germination percentage (95.83%), germination energy (37.5%), and germination value (1.0506) were found in t5 treatment (seed sown in propagator house) and significantly (p<0.05) different from other treatments. collar diameter and leaf number were recorded after three and four months of seed germination. after 3 months of the last germination, maximum shoot height (46.6 cm) was revealed in t2 (seeds immersed in normal water for 48 hours and sown in polybags) treatment. collar diameter (6.02 mm) and leaf number (12.6) were recorded highest in t2 treatment. the lowest diameter (4.23 mm) and leaf number (5.8) were found in t4 treatment (seeds soaking in hot water for 1 minute and sown in propagator house). finally, seeds sown in the propagator house (sand media) revealed comparatively better germination behaviour but low growth performance. seeds treated with normal water for 48 hours treatment revealed appropriate for vigour and quality seedlings production for t. citrina. keywords: treatments, germination, vigour, seedlings, medicinal 1. introduction medicinal plants are the life-saving elements of forest products and play a significant role in the health care of rural people all over the world. they offer essential raw materials for the production of conventional and modern medicines and important therapeutic agents (ghani, 2003; islam et al., 2016). as stated by world health organization (who), there are almost 21,000 medicinal plant species all over the world (penso, 1980). in bangladesh, around 500 plant species including trees, herbs, and shrubs used as medicinal plants because of their therapeutic properties (ghani, 2000). in another study, yusuf et al. (2009) documented 747 plant species have therapeutic properties in bangladesh. terminalia citrina (gaertn.) roxb. ex. fleming, belonging to combretaceae family, a valuable medicinal tree of bangladesh. the medium to large sized deciduous tree having very young shoots are shining, rusty hairy, soon glabrate. bark light grey, vertically fissured, exfoliating in large flakes, inner bark light yellow, turning brown. leaves sub-opposite, elliptic to oblong-lanceolate. flowers small, dull-yellow, sessile in terminal spikes. fruit a drupe, oblong-lanceolate, about 5 cm long, smooth, orange-yellow when ripe, obscurely 5-cornered when dry (das and alam, 2001). it is originated in deciduous forests throughout the greater part of india, myanmar, sri lanka, pakistan, and bangladesh (hossain et al., 2005). in bangladesh, the species occurs naturally in the forests of sylhet, chattogram, chittagong hill tracts, dhaka, mymensingh and also planted as avenue tree (das and alam, 2001). the fruits are used for medicinal purposes in combination with emblica officinalis and terminalia bellirica, known as the name of “triphola”. the ayurvedic recipe ‘triphola’ is effectively and widely used in various ailments such as skin diseases, eye disorders, constipation, chronic lung disease, acidity, digestion, and assimilation (kanjilal et al., 1984; ara et al., 1997). seeds are used in stomach aches and intestinal diseases (lev and amar, 2000). the plants also used in asthma, diarrhea, anemia, arthritis, cough, cardiac disease, infections, hepatomegaly (soe and ngwe, 2004). the timber is very hard, fairly durable, and used for building structures, furniture, agricultural implements, carts, and other purposes. because of the hard seed coat and thick fleshy pulp, germination percentage of seeds is low (<50%) and requires more time to germinate (up to 2-3 months) (luna, 1996). suitable nursery and plantation techniques, management systems of the species are pre-requisite to make a plantation program fruitful. lately, interest in producing quality seedlings by application of upgraded and modern nursery techniques has augmented (gera and ginwal, 2002). in the case of region-specific biodiversity conservation and restoration plans, integrated information of the seed collection, storage, seed germination requirements, and seedlings growth performance of native tree species are crucial (khurana and singh, 2001; smith et al., 2008), but most of the studies are concentrated on fast-growing species only. the selection of appropriate pre-sowing treatment is vital for quick and maximum seed germination (thapa and gautam, 2006). hard coated seeds need more time to germinate and thus, direct sowing is not effective (anon., 1972). proper pre-sowing treatments of seeds can stimulate germination time and germination process (azad et al., 2006; azad et al., 2011; azad et al., 2012). the effect of pre-sowing treatments on seed germination of a few tropical forest tree species have been informed by several authors (khan et al., 2001; haider et al., 2014; nandi et al., 2020 and dey et al., 2020). therefore, an endeavour has been made to study the effect of pre-sowing treatments on seed germination to identify appropriate pre-sowing treatment for terminalia citrina. 2. materials and methods 2.1 study site the study was carried out in the nursery of the institute of forestry and environmental sciences, university of chittagong, chattogram (lies between 91°50´e longitude and 22°30´n latitude) (hossain et al., 2005) (figure 01). the climate is tropical monsoon with an average monthly highest temperature of 29.75° c and a monthly lowest of 21.24° c. the maximum temperature usually occurs in may at 32.60° c and the minimum in january at 14.10° c (peel et al., 2007). 38 dey et al. /journal of tropical forestry and environment vol. 11 no. 02 (2021) 37-47 figure 01. map showing the location of university of chittagong in bangladesh 2.2 seed collection t. citrina fruits were collected from kalurghat forest depot area, chattogram, bangladesh during february 2019. mature seeds were collected from selected plus trees. seeds were extracted manually from mature fruits by depulping method. then dried in the open sun for three days. randomly selected seeds and fruits information like length, width and weight was recorded. only healthy seeds were used for the experiment. 2.3 experimental design the soil used for filling polybags were collected from the forest floor, dried and sieved well (<3 mm) and mixed with decomposed cow dung in a ratio of 3:1. 15×10 cm size polybags were used for the experiment. the media used in the propagator house were fine sylhet sand. forest topsoil was used in the open nursery bed. the study was made up of 6 treatments (including control) with 3 replications (15 seed per replication) in a randomized complete block design. forty-five (45) healthy seeds were chosen randomly for each treatment. daily germination progress was recorded as soon as the seeds start germination. seedlings raised in open nursery bed and propagator house were transferred to polybag after one month of the last germination of seeds. the pricked-out seedlings were kept in shade for 2 weeks and then transferred to sunlight. proper care and maintenance were done regularly. at the end of two and three months of seed germination, three vigor seedlings from each replication were selected for measuring shoot height, collar diameter and leaf number of the seedlings. the pre-sowing treatments are as: t0-seeds without any treatment (control) t1-seeds soaking in normal water for 24 hours and sown in polybags (24º c) t2-seeds soaking in normal water for 48 hours and sown in polybags (24º c) 39 t3-fruits sown in seedbed t4-seeds soaking in hot water for 1 minute and sown in propagator house (80º c) t5-seeds sown in propagator house figure 02. fresh fruits of terminalia citrina figure 03. dry fruits of t. citrina figure 04. a seedling of t. citrina figure 05. t. citrina seedlings raised in polybag 2.4 data collection and analysis 2.4.1 germination percentage the number of seeds out of 100 seeds from the starting of germination to the termination of germination (kumar, 1999). germination % (gp)= no of seed germinated no. of seed sown ×100 2.4.2 cumulative germination % (cgp) it assessed at the end of seed germination by summed up daily germination (hasnat et al., 2019). cgp= cumulative number of seeds germinated number of seeds sown ×100 2.4.3 germination energy (ge) it is measured by computing the daily germination percentage of its peak time (dwivedi, 1993). .4.4 germination index (gi) according to aosa (1983), gi was calculated using this formula. gi = no.of germinated seeds days of first count +…+ no.of germinated seeds days of first count (1) (2) (3) 40 dey et al. /journal of tropical forestry and environment vol. 11 no. 02 (2021) 37-47 2.4.5 mean germination time (mgt) it calculates the rate and the time-spread of germination (bewley et al., 2013; soltani et al., 2015) and it should determine the time to half of the germination. the formula; mgt= 𝛴𝐷𝑛/𝛴𝑛, (4) where, d=the number of days counted from the starting of germination, n=the number of seeds that were germinated on day d (ellis and roberts, 1981; afzal et al., 2005). 2.4.6 germination uniformity (gu) it was calculated by using the formula. gu= σn (σ(fn-t)^2×n) where, t is the time in days, beginning from day 0, the day of germination, and n is the number of seeds germinated at t and f are alike to mgt (abdolahi et al., 2012). 2.4.7 germination value (gv) it was calculated by multiplication of the peak value of germination and mean daily germination (hasnat et al., 2019). gv=peak value of germination×mean daily germination 2.4.8 germination capacity it is the percentage of seeds germinated in an experiment from the starting to end. it was classified as follows: a) 90-100%-very good, b) 70-90%-good, c) 50-70%-average, d) 30-50%-poor, e) 20-30%-very poor, and f) less than 10%-extremely poor (kumar, 1999). 2.5 statistical analysis all the recorded data were analyzed statistically by using computer package software spss ver. 23. duncan’s multiple range test (dmrt) was employed to define the statistical significance and it was shown by different letters in different tables. 3. results 3.1 morphological features of seeds the average length and width of fruits were found 2.412±0.051 cm and 1.054±0.013 cm respectively. around 714 fruits were found per kg. the average length and width of seeds were 1.732±0.089 cm and 0.784±0.02 cm respectively. around 2,173 seeds were found per kg (table 01). table 01. seed length, width and number of seeds per kg of t. citrina length (cm) width (cm) weight/seed (g) number/kg fruit 2.412±0.051 1.054±0.013 1.4±0.045 714 seed 1.732±0.089 0.784±0.02 0.46±0.02 2,173 the results indicated that three tree species had variable effects on the soil composition and it varied by the depth of the soil layer (table 01). the data were expressed as the mean for soil depth, sampling site, and type of species. 3.2 germination performance the germination behaviour of t. citrina seeds was affected by different pre-sowing treatments in this study. seed germination starts first in t5 and t4 (42 th day) after the seeds was sown and t3 required maximum time (47th day) to initiate germination. maximum germination percentage (95.83%) was recorded in t5 (seeds sown in propagator house) followed by 75% in t4 (seeds soaking in hot water for 1 minute and sown in propagator house), 58.3% in t2 (seeds soaking in normal water for 48 hours and sown in polybags), and 33.3% in t0 (control). germination percentage was lowest (16.7%) in t3 and significantly (p<0.05) different from other treatments. the minimum germination period (43.3 days) was found in t4, t5 respectively and maximum (5) (6) 41 germination period (54.3 days) was recorded in t0 (table 02). table 02. germination response of t. citrina seeds in different pre-sowing treatments treatments germination start after (days) germination end after (days) germination period (days) germination (%) germination capacity t0 43 59 54.33 a* 33.33 c poor t1 44 72 52.00 a 20.83 c very poor t2 44 71 50.00 ab 58.33 b average t3 47 56 52.23 a 16.67 c extremely poor t4 42 57 43.33 b 75.00 b average t5 42 59 43.33 b 95.83 a very good *means followed by the same letter(s) in the same column do not vary significantly at p<0.05, according to duncan’s multiple range test (dmrt). the maximum germination index (0.5569) was recorded in t5 and significantly (p<0.05) different from other treatments. highest germination energy (37.5%) was found in t5 and lowest (16.7%) in t1 and t3. the germination uniformity revealed no significant difference among the treatments. maximum germination value (1.0506) was recorded in t5 which is significantly (p<0.05) different from other treatments and minimum (0.0387) in t3. mean germination time was maximum (56.67) in t1, followed by t2 (55.43) and lowest in t5 but mgt showed no significant difference among the treatments (table 03). table 03. germination response of t. citrina seeds in different pre-sowing treatments treatments germination energy (%) germination index (gi) mean germination time (mgt) germination uniformity (gu) germination value t0 20.83 ab* 0.0514 b 52.89 a 0.0007 a 0.1299 c t1 16.67 b 0.02999 b 56.67 a 0.0007 a 0.0477 c t2 25.00 ab 0.0889 ab 55.43 a 0.0012 a 0.3428 c t3 16.67 b 0.0259 b 51.67 a 0.0013 a 0.0387 c t4 29.17 ab 0.1302 ab 46.78 a 0.0013 a 0.7080 b t5 37.50 a 0.5569 a 46.73 a 0.0011 a 1.0506 a *means followed by the same letter(s) in the same column do not vary significantly at p<0.05, according to duncan’s multiple range test (dmrt). 3.3 mean cumulative germination percentage to obtain cumulative germination percentage for each treatment, daily germination percentages were summed. the cumulative germination of t5 treatment starts after 42 days of seed sown and rose rapidly and continued germination up to 96 % within 60 days. in t0 treatment, germination starts at 43rd day and reached 33.3% gradually. t3 showed lowest cumulative germination percentage (16.7 %) (figure 06). 42 dey et al. /journal of tropical forestry and environment vol. 11 no. 02 (2021) 37-47 figure 06. cumulative germination percentage of t. citrina seedlings in different pre-sowing treatments 3.4 growth performance of the seedlings different treatments affect the morphological growth of t. citrina seedlings differently. after 3 months of seed germination, the highest mean shoot height (46.6 cm) was recorded in t2 (seeds soaking in normal water for 48 hours and sown in polybags) and the lowest (30.23 cm) was observed in t4 (seeds soaking in hot water for 1 minute and sown in propagator house). t0 treatment revealed 42.30 cm shoot height (figure 07). figure 07. growth performance of t. citrina seedlings in response to different pre-sowing treatments collar diameter and leaf number were recorded at 3-and 4-months old seedlings. the highest collar diameter (6.02 mm) attained in t2 treatment (seeds soaking in normal water for 48 hours and sown in polybags) and lowest (4.23 mm) in t4 treatment (seeds soaking in hot water for 1 minute and sown in propagator house). maximum number of leaf (12.6) produced in t2 and minimum (5.8) in t4 treatment (table 4). 0.00 20.00 40.00 60.00 80.00 100.00 120.00 4 2 4 4 4 6 4 8 5 0 5 2 5 4 5 6 5 8 6 0 6 2 6 4 6 6 6 8 7 0 7 2 7 4 7 6 7 8 8 0 c u m u la ti v e g e rm in a ti o n % days after seed sown t0 t1 t2 t3 t4 t5 26 23.17 35.7 25.74 20.34 21.56 42.3 36.44 46.6 39.45 30.23 31.45 0 10 20 30 40 50 60 t0 t1 t2 t3 t4 t5 sh o o t h e ig h t (c m ) treatments 2 month 3 month 43 table 04. mean collar diameter and leaf number of t. citrina seeds in different pre-sowing treatments treatments collar diameter (mm) leaf number 3 months 4 months 3 months 4 months t0 4.92±0.20 5.81±0.36 9.2±0.66 11.6±0.81 t1 3.9±0.17 5.01±0.09 6.4±0.24 9.8±0.80 t2 5.26±0.48 6.02±0.28 10.4±1.17 12.6±1.12 t3 3.88±0.15 4.74±0.20 7.6±0.51 9±0.71 t4 3.02±0.14 4.23±0.17 4.8±0.37 5.8±0.66 t5 3.32±0.06 4.58±0.19 6.4±0.51 7.8±0.97 4. discussion the science of seed biology encompasses the development and physiology of seeds until they finally germinate or fail to do so (schmidt, 2000). germination and seedling establishment are critical stages that affect both quality and quantity of crop yields (subedi and ma, 2005). the present findings of the study on terminalia citrina found that seeds sown in propagator house provide the highest germination percentage (95.83%). seeds soaking in normal water for 48 hours was 58.3% and in control 33.3% germination respectively. highest germination energy (37.5%), germination value (1.0506), germination index (0.5569), and lowest mean germination time (46.73) observed in propagator house. the minimum germination period (43.3 days) was found in propagator house and maximum (54.3 days) recorded in control treatment. this study supports the findings of acacia spp. where sand is a suitable medium for seed germination (ista, 1993). sand as a germination substratum is preferred for large seed-producing tree species (magini, 1962). lithocarpus elegans showed the highest germination percentage in propagator house (nandi et al., 2019). maximum shoot height (46.6 cm), collar diameter (6.02 mm), and leaf number (12.6) recorded in t2 (seeds soaking in normal water for 48 hours and sown in polybags) treatment and t4 (seeds soaking in hot water for 1 minute and sown in propagator house) showed the lowest performance. dey and hossain (2019) reported that suregada multiflora seedlings raised in propagator house showed the highest germination and survival rate, but the growth rate was lowest as sandy media failed to provide sufficient nutrients for growing plants. according to hossain et al., (2005) t. chebula fruits de-pulping at two ends and soaking in cold water for 48 hours treatments revealed the highest germination (66.70%) and growth performance. whole fruits of t. chebula soaking in cold water for 48 hours with successive treatments by 10% dilute h2so4 for 20 minutes revealed 70% germination (rashid et al., 1990). ara et al. (1997) showed that clean seeds revealed maximum germination (50%) and initial growth. nainar et al. (1999) applied different pre-sowing treatments in t. chebula seeds and the highest germination percentage (60%) recorded in mechanical scarification treatment. hasnat et al. (2019) revealed soaking in water at room temperature for 48 hours is the best treatment for castanopsis indica species. according to haider et al. (2014) acacia catechu obtained the highest germination percentage (80-81%) soaking in cold water for 24 hours. so, from the study for terminalia citrina species, sandy media is suitable to get maximum germination but not vigor seedlings production. for a successful plantation program, seedling's morphological features such as collar diameter, shoot height, leaf and node number, etc. should be considered. hence, seeds soaking in normal water for 48 hours and sown in polybags is suggested for vigour seedlings production of t. citrina species. 5. conclusion seed’s pre-sowing treatments significantly affect the germination of terminalia citrina. seeds sown in the propagator house showed maximum germination percentages but lowest growth performance. in contrast, seeds treated with normal water for 48 hours and sown in polybags produced vigour and quality seedlings at the initial stage. the result of the present study recommends that nursery 44 dey et al. /journal of tropical forestry and environment vol. 11 no. 02 (2021) 37-47 owners or other seedling producer organizations treat t. citrina seeds with water for 48 hours at room temperature and sown in polybags in large-scale plantation programs. acknowledgment the authors are highly grateful to the natp phase 2 project id#074 ifescu component supported by the natural resources division of bangladesh agricultural research council (barc) for providing financial support and necessary suggestions under project titled "exploration, identification, characterization, multiplication and ex-situ conservation of endangered forest genetic resources including medicinal plants of bangladesh”. the authors would like to thanks all staff of “seed research laboratory” and nursery of the institute of forestry and environmental sciences, university of chittagong. references abdolahi m., andelibi b., zangani e., shekari, f. and jamaatie-somarin, s., 2012. effect of accelerated aging and priming on seed germination of rapeseed (brassica napus l.) cultivars. international research journal of applied and basic sciences 3:499-508. afzal i., basra s.m.a., iqbal a., 2005. the effects of seed soaking with plant growth regulators on seedling vigour of wheat under salinity stress. journal of stress physiology and biochemistry 1:6-14. anonymous, 1972. the wealth of india. 9:225-227. aosa, 1983. seed vigour testing handbook. contribution no. 32 to the handbook on seed testing. ara r., merry s.r., siddiqi n.a., 1997. cultivation and uses of twelve medicinal plants of bangladesh. bulletin 7, minor forest products series, bangladesh forest research institute, chittagong. 27-31. azad m.s., islam m.w., matin m.a., bari m.a., 2006. effect of pre-sowing treatment on seed germination of albizia lebbeck (l.) benth. south asian journal of agriculture1 (2):32-34. azad m.s., manik m r., hasan m.s., matin m.a., 2011. effect of different pre-sowing treatments on seed germination percentage and growth performance of acacia auriculiformis. journal of forestry research 22 (2):183-188. azad m.s., biswas r.k., matin m.a., 2012. seed germination of albizia procera (roxb.) benth. in bangladesh: a basis for seed source variation and pre-sowing treatment effect. forestry study in china 12 (2):124-130. bewley j.d., bradford k.j., hilhorst h.w.m. and nonogaki h., 2013. seeds: physiology of development, germination and dormancy. 3rd edition, springer, new york. das d.k., alam m.k., 2001. trees of bangladesh. bangladesh forest research institute, chittagong, 1-342. dey s., hossain m.k., 2019. containers effects on seed germination and initial growth performance of suregada multiflora (ban-naringa) seedlings: a native lesser-known tree species in bangladesh. indian forester 145(4):381-386. dey s., hossain m.k., miah m.d., 2020. germination and initial seedlings growth response of ehretia serrata in different pre-sowing treatments. international journal of forestry, ecology and environment 2(1):78-85. dwivedi a.p., 1993. a text book of silviculture. international book distributors. 9/3 rajpur road, dehradun-248001, india. 1-505. ellis r.h., roberts e.h., 1981. the quantification of aging and survival in orthodox seeds. seed science and technology 9:373-409. gera m., ginwal, h.s., 2002. preliminary observations on field trial of root trainer raised seedlings, indian forester 128 (1): 19-26. ghani a., 2000. vheshaja oshud (herbal medicine), bangla academy, dhaka, bangladesh. 279. ghani a., 2003. medicinal plants of bangladesh. asiatic society of bangladesh, dhaka. 603. 45 haider m.r., alam m.s., hossain, m.a., 2014. effect of pre-sowing treatment on seed germination and seedlings growth attributes of acacia catechu willd. in nursery and field conditions. international journal of latest research in science and technology 3(4):214-219. hasnat g.n.t., hossain m.k., alam, m.s., bhuiyan, m.k., hossain m.a., 2019. germination and initial seedling growth performance of vitex peduncularis wall. ex schauer a threatened native tree species of bangladesh. journal of bioscience and agriculture research 20(2):17001708. hasnat g.n.t., hossain m.a., hossain m.k., uddin, m.m., 2019. effect of pre-sowing treatments on germination and initial seedling growth of castanopsis indicaan endangered tree species in bangladesh. journal of forest and environmental science 35(4):223-231. hossain m.a., arefin m.k., khan b.m., rahman, m.a., 2005. effects of seed treatments on germination and seedling growth attributes of horitaki (terminalia chebula retz.) in the nursery. research journal of agriculture and biological sciences 1(2):135-141. international seed testing association (ista), 1993. international rules for seed testing, seed science and technology 21:1-288. islam s.a., miah m.a.q., alam m.m., rasul m.g., 2016. initial growth performance of ten woody medicinal tree species in eastern coastal belt of bangladesh. journal of bioscience and agriculture research 11(1):930-935. kanjilal u.n., kanjilal p.c., das a., 1984. flora of assam. vol. i-vi. dehra dun, india. khan b.m., koirala b., hossian m.k., 2001. effect of different pre-sowing treatments on germination and seedling growth attributes in ghora neem (melia azedarach l.). malaysian forester 64 (1): 4-20. khurana e. and singh j., 2001. ecology of seed and seedling growth for conservation and restoration of tropical dry forest: a review. environmental conservation 28:39-52. kumar v., 1999. nursery and plantation practices in forestry. scientific publishers, 5a, new pali road, p.o. box 91, jodhpur-342001. 65-159. lev e., amar, z., 2000. ethnopharmacological survey of traditional drugs sold in israel at the end of the 20th century. journal of ethnopharmacology 72(1-2):191-205. luna r.k., 1996. plantation trees. international book distributors, dehra dun. 975. magini e., 1962. forest seed handling, equipment and procedures. ii. seed treatments, storage, testing and transport. unasylva 16(1):20-35. nainar p., sundharaiya k., ponnuswamy, v., 1999. germination studies in kadukkai (terminalia chebula). south indian horticulture 47(1-6):373-374. nandi r., dey s., hossain m.k., 2020. conservation of a native threatened tree species quercus gomeziana a. camus in bangladesh. journal of forest and environmental science 36(1):1-6. nandi r., dey s., hossain m.k., 2019. germination and seedling growth response on lithocarpus elegans (fagaceae) seeds to pre-sowing treatments and fertilizer application. asian journal of research in agriculture and forestry 4(4):1-7. peel m.c., finlayson b.l., mcmahon, t.a., 2007. updated world map of the köppen-geiger climate classification. hydrology and earth system sciences discussions 4(2):439-473. penso g., 1980. the role of who in the selection and characterization of medicinal plants (vegetable drugs). journal of ethnopharmacology 2(2):183-188. rashid m.h., mohiuddin m., ara r., alam, m.j., 1990. medicinal plant and its cultivation. bulletin 4, minor forest products series, bangladesh forest research institute, chittagong. 17. (in bangla). schmidt l., 2000. guide to handling of tropical and subtropical forest seeds, danida forest seed center, humleback, denmark. 1-510. smith n., zahid, d.m., ashwath, n., midmore, d.j., 2008. seed ecology and successional status of 27 tropical rainforest cabinet timber species from queensland, forest ecology management 256 (5):1031-1038. 46 dey et al. /journal of tropical forestry and environment vol. 11 no. 02 (2021) 37-47 soe k., ngwe, t.m., 2004. medicinal plants of myanmar, combretaceae, forest resource environment development and conservation association (freda). series-1. soltani e., ghaderi-far, f., baskin, c.c., baskin, j.m., 2015. problems with using mean germination time to calculate rate of seed germination. australian journal of botany 63: 631-635. subedi k.d., ma b.l., 2005. seed priming does not improve corn yield in a humid temperate environment. agronomy journal 97:211-218. thapa h.b. and gautam s.k., 2006. augmentation of germination in sapindus mukorossi due to acid scarification in jhanjhatpur nursery, banko janakari 16(1):14-20. yusuf m., begum j., hoque m.n., uddin, c.j., 2009. medicinal plants of bangladesh. bangladesh council of scientific and industrial research laboratories, chittagong. 47 microsoft word 4 perera perera et al., /journal of tropical forestry and environment vol. 2, no. 01 (2012) 26-35 26 effect of growth rate on wood specific gravity of three alternative timber species in sri lanka; swietenia macrophylla, khaya senegalensis and paulownia fortunei p.k.p. perera* 1 , h.s. amarasekera 1 , n.d.r. weerawardena 2 1 department of forestry and environmental sciences, university of sri jayewardenepura 2 forest research center, kumbalpola, sri lanka forest department date received: 28-11-2011 date accepted: 29-03-2012 abstract with increasing private sector investments in commercial forestry, it is apparent that plantation forestry in sri lanka is moving in the direction of managing fast growing timber species for shorter rotations. however, there’s a perceptionthat accelerated growth rates induced by improved forest management practices can result in inferior wood quality. this study tested this perceptionby studying the effect of growth rate on the specific gravity, as a proxy for wood quality, of three alternative timber species grown in sri lanka; swietenia macrophylla, khaya senegalensis and paulownia fortunei. specific gravity remained more or less uniform from pith to bark regardless of the fluctuation of ring width in k. senegalensis while s. macrophylla exhibited a slight increase in specific gravity from pith to bark. this increasing trend was more prominent in p. fortunei. results revealed growth rates represented by ring width showed poor correlations with specific gravity in both s. macrophylla, and k. senegalensis. although p. fortunei showed a statistically significant positive correlation, regression analysis indicated a poor relationship between growth rate and specific gravity. hence it is unlikely that wood specific gravity of the studied species to be influenced by accelerated growth rates. key words: growth rate, specific gravity, ring width, wood quality, swietenia macrophylla, khaya senegalensis, paulownia fortunei 1. introduction forest plantations in sri lanka have steadily increased over the last few decades as the pressure to conserve existing natural forests has increased. numerous reports suggest that the booming economy coupled with expanding population is likely to drive the demand for sawn wood even higher (forest sector master plan, 1995; perera et al., 2006). recognizing the importance of forest plantations in meeting the country’s demand for sawn timber, the government has made provisions such as long-term land leases under concessionary rates for forestry projects to encourage private sector participation in forestry (ministry of environment and natural resources sri lanka, 2002). meanwhile, investments in commercial forest plantations are also on the rise (cbsl, 2004). as such, the upward trend in expansion of forest plantations is also likely to continue. *correspondence: priyan@sjp.ac.lk tel:+94-112758411, fax: +94 112803470 issn 2235-9370 print / issn 2235-9362 online ©2012 university of sri jayewardenepura perera et al., /journal of tropical forestry and environment vol. 2, no. 01 (2012) 26-35 27 at present, sri lanka’s forest plantations are dominated by fast growing exotic timber species such as eucalyptus spp, pines (pinus caribaea and p. patula), teak (tectona grandis), and mahogany (s. macrophylla). in addition to these well-known timber species, both state (forest department) and private sector plantation companies have increasingly become interested in introducing new, commercially valuable, fast growing timber species. among these, k. senegalensis, also known as african mahogany is of special interest. k. senegalensis has been introduced to the country more than 45 years ago as a shade and amenity tree. however, large scale plantation establishment with khaya for timber purposes was initiated about 15 years ago by the forest department. k. senegalensis is predominantly grown in dry and intermediate climatic zones of the country. paulownia fortuneion the other hand is not yet grown by the forest department in large scale, but the private sector is showing interest in this species, possibly due to its fast growth rates and multiple uses (jørgensen and vivekanandan, 2003). however, a major drawback for the promotion, management and efficient utilization of new timber species such as k. senegalensis and p. fortuneiis the lack of information regarding their wood properties and wood quality when grown under localconditions in sri lanka. availability of such information prior to large scale forest plantation establishment plays a crucial role in selecting the species most appropriate for the envisaged end use. even for popular timber species such as s. macrophylla, wood property information when grown under local conditions is rare in the literature (amarasekera, 1996). with increasing private sector investments in commercial forestry, it is apparent that plantation forestry in sri lanka is moving in the direction of managing fast growing timber species for shorter rotations. however, larson (1972) proposed that accelerated growth rates induced by improved forest management practices may result in wood of inferior quality. larson’s argument has been well supported by numerous studies (bhat and bhat, 1983; herman et al., 1998; simatupang et al., 2000). therefore, understanding the effect of growth rate on wood quality is highly important so that forester managers can effectively manipulate tree growth to yield better quality timber. in the context of the three timber species examined in this study, i.e. s. macrophylla, k. senegalensis and p. fortunei, no previous information exists in literature on effects of growth rate on wood quality, especially when grown under local conditions. hence, this study attempts to bridge the information gap by investigating the radial variations of specific gravity with growth rate as measured by ring width. 2. literature review wood properties vary greatly within a tree. wood property variation patterns that arise from apical or cambial aging and positional effects of the crown are regarded as intrinsic. external factors such as environment, site conditions and silvicultural treatments also have impacts on regular patterns of wood variation and these are regarded as extrinsic. wood properties vary within the position in a tree and with the age at which the growth sheath is formed. therefore, systematic radial and axial patterns of wood property variations can be identified (amarasekera and denne, 2002). specific gravity may be the most widely studied property of wood. specific gravity is a function of the proportion of cell wall materials versus cellular voids. many authors identify specific gravity as a key wood property in forest products because it has a major effect on the yield and quality of both fibrous and solid wood products (bhat, 1985; haslett and young, 1990).as such, specific gravity is often considered as a measure of with wood quality (zobel and van buitjenen, 1989; woodcock and shier, 2002). numerous authors have classified timber species based on specific gravity as it is the single best index that can be easily measured to predict strength properties of wood (bhat, 1985; amarasekera, 1996). perera et al., /journal of tropical forestry and environment vol. 2, no. 01 (2012) 26-35 28 the literature contains significant body of research that examines radial variation in wood specific gravity within hardwood trees (lei et al., 1997; bao et al., 2001; woodcock and shier, 2002; amarasekera and denne, 2002; ruwanpathirana, 2002; nock et al., 2009; lin et al., 2012). such studies in general cite the existence of juvenile wood and mature wood as the main cause of radial trends in wood specific gravity. for instance, bao et al. (2001) observed considerable differences in most wood properties (including specific gravity) between plantation-grown juvenile wood and mature wood, and between naturally-grown juvenile wood and mature wood. based on their findings, bao et al. (2001) argued that “wood properties of plantation-grown trees greatly depends on juvenile wood content, and can thus be manipulated effectively through varying rotation age”. generally, the longer the rotation age, the lower the juvenile wood content and superior the wood properties. apart from genetic factors, higher growth rates are often resulting from improved site, nutrient and environmental conditions and intense silvicultural control. there are no certain patterns that hold regarding the relationship between growth rate and wood quality or specific gravity, and literature can be found to support nearly any chosen point of view. the relationship depends on the species and the site concerned as well as on how the growth is expressed (zobel and van buitjenen, 1989). several works based on softwoods emphasize the detrimental effect of growth rate on specific gravity (schmidtling and amburg, 1977; pearson and gilmore, 1980; zhang, 1995; ruwanpathirana, 2002) although examples are available in the review of zobel and van buitjenen, (1989) to illustrate different trends. herman et al. (1998) observed that increasing the growth rate in circumference of norway spruce from 1.7 to 2.7 cm/year by heavy thinning induced a limited decrease in wood density. however, he concluded that the decrease in wood density is so minorthat stand productivity can be improved without significantloss of wood quality. diffuse porous and ring porous hardwoods are affected differently by growth rate. generally, growth rate differences have little effect on specific gravity of diffuse porous hardwoods with few exceptions (macdonald and franklin, 1969; ruwanpathirana, 2002). for instance, ruwanpathirana (2002) observed that in fast growing sites of eucalyptus grandis, the specific gravity increased from pith and thereafter remained constant towards the bark with small fluctuations. specific gravity increased gradually towards bark in slow and medium growth sites. fast growing sites maintain the highest specific gravity from pith to bark. according to briscoe et al. (1963), the specific gravity of s. macrophylla tends to increase with growth rate. zhang (1995) observed growth rate to generally have very little influence on specific gravity of diffuse porous hardwoods. wood density decreases under fast growth rates in certain diffuse porous hardwoods. according to haslett et al. (1991), wood of plantation crops grown on rotations of 10 to 20 years can be of significantly lower density. for example, 14 year old plantation grown eucalyptus deglupta is shown to have 30% lower density than values for the same species grown in papua new guinea. according to zhang (1995), specific gravity does not remarkably decrease with growth rate in ring porous hardwoods, while some species tend to show an increase in specific gravity with increasing growth rates. simatupang et al. (2000) report that s. macrophylla wood from short rotation plantations is of inferior quality to that of matured naturally grown timber.conversely, many studies indicate no significant relationship between tree size representing growth rates and specific gravity of s. macrophylla (chudnoff and geary, 1973; lin et al., 2012).studies to explain the radial variation of specific gravity with growth rate of k. senegalensis and p. fortunei are rare in literature. higher timber yields and uniform wood from shorter rotations are key incentives for developing intensively managed timber plantations (pérez and kanninen, 2005). in the context of the three study species, no adequate data are available in literature to explain the effect of growth rate on wood quality, especially when grown under sri lankan conditions. wood property variations with growth rates in k. senegalensis and p. fortune in general have received scant scholarly attention in both international and perera et al., /journal of tropical forestry and environment vol. 2, no. 01 (2012) 26-35 29 local literature. therefore, the primary objective of this study was to investigate the effect of growth rate on radial variations of specific gravity in species s. macrophylla, k. senegalensis and p. fortunei. 3. materials and methods three sites where s. macrophylla, k. senegalensis and p. fortunei are growing were selected to obtain test specimens. all sites were from the intermediate climatic zone of the country. s. macrophylla were obtained from 79 year-old jak-mahogany plantation in kurunegala. k. senegalensis specimens were obtained from a 49 year-old plantation in kankaniamulla while p. fortunei were from a16 year-old plantation in agaratenna, badulla. fifty trees from each sampling plot were randomly selected and classified into “dominant”, “co-dominant” and “suppressed” based on their dbh. three trees with straight and non-leaningboles from each species belonging to the co-dominant size class were randomly selected and felled. each tree (and sample disk) was named as indicated in table 1 for the ease of reference. sample disks of 2 inch thickness were extracted from each tree at breast height. table 1: age, mean dbh and mean height of selected trees age mean species tree 1 tree 2 tree 3 (years) dbh (cm) height (m) s. macrophylla m1 m2 m3 79 36.0 18 k. senegalensis k1 k2 k3 49 41.8 20 p. fortunei p1 p2 p3 16 22.6 10 each sample disk was planed and sanded to better observe the growth rings. the growth rings were visually identified with the aid of a hand lens. rings were marked along a linear section that goes across the pith, avoiding reaction wood areas. false rings were ignored. ring width was measured using a travelling microscope to an accuracy of 0.01cm. rings were identified and markedto both directions from the pithand the mean value was taken as the ring width of the corresponding ring. the maximum moisture content method proposed by smith (1954) was used to determine the specific gravity of wood. four match-stick sized specimens were extracted from each ring (2 from the left and 2 from the right to the pith) and mean value was taken as the specific gravity corresponding to each ring (figure 1). data were analyzed using minitab 16 statistical software. figure 1: diagram of sample preparation from a disk extracted at breast height 4. results in this study, ring width was the parameter selected to represent growth rate. variations of ring width from pith to bark for the three studied species at breast height level are illustrated in figure 1. in general, ring width showed a gradual increase after first few growth rings in all the studied species. in both s. macrophylla and k. senegalensis, wider growth rings were observed for sheaths corresponding to the period of 3 to 20 years in the tree life history. after that, growth increments gradually declined for sample disk radial section going across pith match-stick sized specimens perera et al., /journal of tropical forestry and environment vol. 2, no. 01 (2012) 26-35 30 both species and remained more or less constant. in p. fortunei, wider growth rings were visible for sheaths corresponding to the period of 3 to 10 years in tree life history. the sharp increase in ring width in p. fortuneiwas followed by a gradual decline towards the bark.for each species, between-tree variations in ring width/growth rate were less prominent. since specific gravityis associated withwood quality, specific gravity was determined for each growth ring in the sample disks forthe three species.the highest mean specific gravity at breast height was recorded for k. senegalensis (0.614) followed by s. macrophylla (0.514) and p. fortunei (0.312) respectively. pith to bark variations of specific gravity of growth rings for the three species are depicted in figure 2. accordingly, in s. macrophylla and k. senegalensi, specific gravity remained fairly uniform with little fluctuations over growth seasons, i.e. specific gravity remained more or less consistent from pith to bark. p. fortune on the other hand, showed a gradual increase in specific gravity from pith to bark. the increase in specific gravity was more prominent after the first 10 growth rings. this radial trend in specific gravity may be explained by the transition between juvenile wood and mature wood. the fluctuations of mean ring width and mean specific gravity of each species with ring number from the pith are shown in figure 3. pearson’s correlations tests were performed for each species to investigate the relationship between the variables ring width and whole ring specific gravity. the results are summarized in table 2. accordingly, no substantial pattern was observedin s. macrophylla suggesting that specific gravity is less affected by the growth rate. however, pearson’s correlations indicated a weak negativerelationship (p=0.034) between ring width and specific gravity (table 2). according to figure 3, it appears that higher specific gravities are associated with narrower ring widths in k. senegalensis, and this is supported by a statistically significant positive correlation reported in figure 2: pith to bark variation of ring width indicating the growth rate of studied species perera et al., /journal of tropical forestry and environment vol. 2, no. 01 (2012) 26-35 31 table 2. p. fortune also exhibited no clear variation pattern in specific gravity with growth rate as measured by ring width. the negative weak correlation between specific gravity and ring width was statistically non-significant at 0.05 level of significance (table 2). table 2: pearson’s correlations between ring width and specific gravity for studies species species correlation ( r ) p value significance (α=0.05) s. macrophylla -0.186 0.034 significant k. senegalensis 0.266 0.008 significant p. fortunei -0.185 0.203 not significant since pearson’s correlation test reported significance (p<0.05) for both s. macrophylla and k. senegalensis, linear regression models were developed to explain the relationship between growth rate and specific gravity for the two species separately. however, linear regression analysis yielded poor coefficient of determination values (r 2 ) for regression models developed for s. macrophylla (r 2 =0.08) andk. senegalensis (r=0.09) indicating the negligible effect of growth rate on whole ring specific gravity. figure 3: pith to bark variation of whole ring specific gravity of studied species perera et al., /journal of tropical forestry and environment vol. 2, no. 01 (2012) 26-35 32 5. discussion changes in wood properties and woodstructure within the trunk from pith outwards are well documented for a wide range of species.an important research area is in distinguishing how wood characteristics are influenced by inherent trends from those that are also affected by growth rate (amarasekera and denne, 2002). a better understanding of these variations helps forester managers to better manipulate growth conditions to produce wood with a desired level of quality. previous researchon the effect of growth rate on wood properties of sri lankan hardwoods have been carried out using sampling methods based on percentage distances from the pith (vivekanandan, 1978; ruwanpathirana, 2002). the present study is the first attempt to investigate the variation of specific gravity of hardwoods based on sampling each ring from the pith. this approach may provide better insights to pith-to-bark variation patterns of specific gravity. ring width, measured using a travelling microscope, was used as an indicator of growth rate.identification of growth rings in s. macrophylla and k. senegalensis was challenging. the number of growth rings observed for these species were well below their corresponding ages (maximum 49 rings for 79 year-old s. macrophylla and 35 rings for 49 year-old k. senegalensis). this scenario can be partially attributed to adverse growth conditions such as droughts that had occurred during the lifetime of trees causing cessation of the cambial activity (larson, 1994). in addition, the presence of discontinuous/false rings was also common in the sample disks. however, for p. fortune, the number of growth rings observed was analogous to the tree age, i.e. 16 growth rings for 16year-old trees. in both s. macrophylla and k. senegalensis, wider growth rings were observed for sheaths corresponding to aperiod of approximately 3 to 20 years in the tree life history. thereafter, growth increments gradually declined for both species and remained more or less constant. given the uniformity ring width specific gravity figure 4: variation of mean specific gravity with growth rate as measured by ring width perera et al., /journal of tropical forestry and environment vol. 2, no. 01 (2012) 26-35 33 of specific gravity/wood quality from pith to bark, this may imply that both s. macrophylla and k. senegalensis can be managed for 20 to 30 year rotations. ring width variation pattern in p. fortunei suggest that the species could be managed for rotations below 20 years. the effect of growth rate on specific gravity of s. macrophylla has been discussed by several authors and the relationship can be considered as inconclusive. briscoe et al. (1963) reported an increase in specific gravity of s. macrophylla with increased growth rates while chudnoff and geary (1973) found no significant relationship between tree size (representing the growth rate) and wood specific gravity. analyzing ring characteristics of 30-year-old s. macrophylla, lin et al. (2012) further concluded that it is unlikely for growth rates of plantation-grown mahogany trees to have a significant impact on wood specific gravity. from the present work, it was observed that specific gravity shows a poor correlation with growth rate measured by ring width. hence it is unlikely that wood specific gravity of these species can be changed by influencing growth rate. in most trees, the first 10 growth rings, or the wood formed during the first 10 years of growth, are considered to be juvenile wood (sanwo, 1987) and wood properties tend to vary greatly in this zone (amarasekera and denne, 2002). in this study, the specific gravity remained more or less uniform from pith to bark regardless of the fluctuation of ring width in k. senegalensis while s. macrophylla exhibited a slight increase from pith to bark. the increasing radial trend in specific gravity was more prominent in p. fortunei. this may suggest that the cambium in p. fortunieitends to produce denser wood as the cambium matures. lin et al. (2012) also observed a gradual increase in specific gravity from pith outwards in plantation grown s. macrophylla. in k. senegalensis, it seems that specific gravity does not considerably change between juvenile wood and mature wood zones, and the cambium produces uniform wood throughout the year. these results can be used to help determine optimal rotation ages for the species researched in this study. 6. conclusion no substantial and definite relationship appears to exist between whole ring specific gravity and ring width representing the growth rate in s. macrophylla, k. senegalensis and p. fortuniei. hence, results suggest that growth rate does not significantly affect specific gravity or wood quality of these species. references amarasekera, h. 1996. alternative timber species; a review of their properties and uses,. in h. s. amarasekera, & s. g. banyard (ed.), forestry for development: proceedings of the annual forestry symposium 1995, december (pp. 76-88). sri lanka: department of forestry and environmental sciences. amarasekera, h., and denne, m. 2002. effects of crown size on wood characteristics of corsican pine in relation to definitions of juvenile wood, crown formed wood and core wood. forestry, 75(1), 51-61. bao, f., jiang, z. h., jiang, x. m., lu, x. x., luo, x. q., and zhang, s. y. 2001. differences in wood properties between juvenile wood and mature wood in 10 species grown in china. wood science and technology, 35(4), 363-375. bhat, k m and bhat, k. v. 1983.wood properties of 1-year-old eucalytus tereticornis, iufro conference division 5 madison, wisconsin, 1 p (summary). bhat, k m. 1985. properties of selected lesser-known tropical hardwoods.journal of the indian academy of wood science, 16(1), 26-35. briscoe, c b, harris, j. b, and wyckoff, f. 1963, variation of specific gravity in plantation-grown trees of big-leaf mahogany.caribbean forestry, 24, 6774. perera et al., /journal of tropical forestry and environment vol. 2, no. 01 (2012) 26-35 34 cbsl, 2004.annual report of the monetary board of the hon. minister of finance for the year 2004.central bank of sri lanka, colombo 01, sri lanka. chudnoff, m and geary, t f. 1972. on the heritability of wood density in swietenia macrophylla, turriablba 23, 359-36. forestry sector master plan,1995.forest sector development division, ministry of agriculture, lands and forestry.511 pp. haslett, a.n. and young,g.d. 1990.plantation grown tropical timbers 1.wood property and processing evaluation procedures to improve usage.journal of tropical forest science, 3(2):131-139. haslett, a.n., young, g.d, and britton, r.a.j. 1991. plantation grown tropical timbers 2.properties, processing and uses.journal of tropical forest science, 3(3): 229-237. herman, m., dutilleul, p., & avella-shaw, t. (1998). growth rate effects on temporal trajectories of ring width, wood density, and mean tracheid length in norway spruce (picea abies (l.) karst.). wood and fiber science, 30(1), 6-17. hua lei, h., gartner, b., and milota, r. 1997. effect of growth rate on the anatomy, specific gravity, and bending properties of wood from 7-year-old red alder (alnus rubra). canadian journal of forest research, 27, 80-85. jørgensen, i., and vivekanandan, k. 2003. private forestry based on paulownia in sri lanka: an appraisal of the outgrower scheme presented by paulownia plantations ltd. norway: noragric agricultural university of norway. larson, p r (1972), evaluating the quality of fast-grown coniferous wood, proceedings west for conf. seattle, washington, 17. lin, c., chung, c., cho, c.,and yang, t. 2012. tree ring characteristics of 30-year old swietenia macrophylla plantation trees. wood and fiber science, 44 (2), 1-12. mac donald, r.g.and franklin, n.j. 1969.pulp and paper manufacturer, vol.1.the pulping of wood 2 nd ed. mcgraw-hill, ny. ministry of environment and natural resources sri lanka, 2002.national report of sri lanka to the world summit on sustainable development.ministry of environment and natural resources, sri lanka.35-36. nock, c., geihofer, d., grabner, m., baker, p., bunyavejchewin, s., and hietz, p. 2009. wood density and its radial variation in six canopy tree species differing in shade-tolerance in western thailand. annals of botany, 104(2), 297-306. pearson, r.g. andgilmore, r.c. 1980. effect of fast growth rate on the mechanical properties of loblolly pine. forest products journal, 30(5):47–54. perera, p., vlosky, r., amarasekera, h., and de silva, n. 2006. forest certification in sri lanka. forest products journal, 56(11/12), 5-11. pérez, d. &kanninen, m. 2005.effect of thinning on stem form and wood characteristics of teak (tectonagrandis) in a humid tropical site in costa rica. silva fennica 39(2): 217–225. ruwanpathirana, n. d. 2002.variation of some wood properties of eucalyptus grandis and pinus caribaea in different site classes, phd thesis. department of botany, university of ruhuna, sri lanka, 30-133. sanvo, s. 1987. the charactoristics of the crown-formed and stem-formed wood in plantation grown teak (tectona grandis l.f) in nigeria. journal of institute of wood science, 11(2), 85-88. schmidtling, r.c. and amburgey, t.l. 1977. growth and wood quality of slash pines after early cultivation and fertilization.wood science, 9(4): 154-159. simatupang, m., yamamoto, k., hinghong, c., and matsumoto, k. 2000. properties of teak wood (tectona grandis l.f) and mahogany (swietenia macrophylla king) from manmade forest and influence on utilization. jircas. smith, d. 1954. maximum moisture content method for determining specific gravity of small wood samples. usa: usda forest service forest products laboratory. perera et al., /journal of tropical forestry and environment vol. 2, no. 01 (2012) 26-35 35 woodcock, d., & shier, a. d. (2002). wood specific gravity and its radial variations: the many ways to make a tree. trees structure and function, 16(6), 437-443. zhang, s.y. 1995. effect of growth rate on wood specific gravity and selected mechanical properties in individual species from distinct wood categories.wood science and technology, 29(6); 451-465. zobel, b. j., and van buijtenen, j.p. 1989.wood variation its causes and control, springer-verlag, berlin, germany, 354-358pp. chapter 4 36 lead and cadmium removal from aqueous medium using coir pith as adsorbent: batch and fixed bed column studies b.m.w.p.k. amarasinghe department of chemical and process engineering, university of moratuwa, sri lanka. date received: 31-03-2011 date accepted: 02-09-2011 abstract coir pith was used as an alternative to commonly available adsorbents for heavy metal ion removal from aqueous solutions. batch and fixed bed column experiments were conducted to study adsorption characteristics of cd and pb onto coir pith. coir pith is an effective adsorbent for pb and cd removal. the adsorbent dose, metal ion concentration and the solution ph affects the degree of adsorption. the maximum adsorption was observed at solution ph values above 5. the equilibrium data was satisfactorily fitted to langmuir and freundlich isotherms. pb showed higher adsorption capacity compared to cd under the experimental conditions. kinetic studies revealed that pb and cd uptake was fast within first 10 to 15 min of contact time and data fits to pseudo second-order model. breakthrough curve data fits to linear bed depth service time (bdst) model and bed capacities for pb and cd were 41 and 28 mg/ g of coir pith respectively. key words: adsorption, heavy metals, coir pith correspondence: e-mail padma@cheng.mrt.ac.lk, tel + 9411 2640474 issn 2235-9370 print/ issn 2235-9362 online ©2011 university of sri jayewardenepura journal of tropical forestry and environment vol. 01, no. 01 (2011) 36-47 37 1. introduction heavy metals are continuously released into water sources from natural and industrial processes. some heavy metals such as cadmium and lead are highly toxic as ions and/or in neutral forms. among the number of waste treatment processes available, the adsorption is widely used especially for solutions at low metal concentrations (corbitt, 1999). however, commercially available adsorbents are expensive and hence there is a significant need for development of alternative adsorbents that are low cost and effective. investigations have been conducted to test various plant materials as low-cost adsorbents for heavy metal ion removal. studies have shown that materials can be treated physically, chemically or thermally to enhance adsorption properties (babu and ramakrishna, 2003). rice husk (chuah et.al., 2005, amarasinghe et al., 2005), tea waste (amarasinghe and williams, 2007, malkoc and nutoglu, 2005, 2006), saw dust (sciban, 2006, shukla, 2002,2005), tree leaves and barks (baig, 1999, palma et al., 2003) and coconut husk based products (santhy and selvapathy, 2006, namasivayan and sangeetha, 2006, macedo et al., 2006 shukla et al., 2006, conrad and hansen, 2007) have all been tested for their adsorption characteristics for dyes, heavy metals and other organic matter. this work investigates the potential of raw coir pith for cd and pb removal from aqueous solutions. batch adsorption tests were conducted to determine equilibrium characteristics, kinetic data and factors affecting adsorption. in industry, fixed-bed columns are widely used for adsorption and, hence, fixed bed column tests were conducted to investigate the practical applicability. breakthrough curves were obtained and adsorption characteristics in column operations were determined. 2. materials and methods 2.1 preparation of the adsorbent coir pith was obtained from the coconut-coir pith bricks imported to usa from sri lanka (the lazy gardener, whittier, california). soluble and coloured components were removed from coir pith by washing with water. the process was repeated until the water was virtually colourless. the coir pith was then washed with distilled water and oven dried for 12 hrs at 85 °c. the dried coir pith was sieved (350"850 µm) and stored in sealed polythene bags until use. 2.2 synthetic waste water preparation synthetic wastewater solutions were prepared by dissolving analytical grade cd(no 3 ) 2 .3h 2 o and pb(no 3 ) in distilled water to obtain 1000 mg of metal per l of solution. the stock solutions were diluted to the required concentration for experiments. the ph of the solution was measured and observed as 5.5±0.5, and no chemicals were added to change ph except for the ph experiments. 2.3 batch adsorption tests batch adsorption tests were conducted by mixing known weight of coir pith and solution of known metal-ion concentration (in the range 50"150 mg/l). the mixture was shaken in a mechanical shaker and 5 ml samples of solution were withdrawn from the bottle at known time intervals. the sample was amarasinghe /journal of tropical forestry and environment vol. 01, no. 01 (2011) 36-47 38 filtered to remove any fine particles and analyzed for the metal ion. a series of experiments were conducted to determine the effect of adsorbent dose, initial metal ion concentration, equilibrium isotherms and effect of solution ph. the solution ph was at 5.5±0.5 (except for effect of ph experiments) and all the experiments were conducted at room temperature at 26±2 °c. 2.4 fixed bed experiments fixed bed column adsorption experiments were conducted in a small 1.5 cm diameter glass column. the column was filled with a known weight of coir pith to obtain the required bed height. the metal ion solution containing 100 mg/l of cd or pb was fed to the column at a constant flow rate of 5.5 ml/min through the bed using a peristaltic pump. the solution leaving the bottom of the column was collected at various time intervals and the samples were analyzed. the batch and column adsorption experiments were performed in duplicate to observe the reproducibility. 2.5 metal analysis and adsorbent characterization atomic absorption spectrophotometer (perkin elmer-model 3110) with an air-acetylene flame and hollow cathode lamps for cd and pb was used for metal ion analysis. the absorbance of the samples was read in triplicate. the surface area of coir pith was measured using bet surface area analyzer (quantachrome). the size of the coir pith was determined by sieve analysis. true and bulk densities of coir pith were also determined using the specific gravity bottle method. scanning electron microscope photographs were obtained for coir pith using field emission sem s4700 (hitachi corporation). 3. results and discussion 3.1 properties of coirpith physical properties of coir pith determined as described above are listed in table 1. the textural structure examination of coir pith particles can be observed from the sem photographs in figure 1(a). the pore size distribution is shown in figure. 1 (b). 3.2 effect of adsorbent dose the effect of adsorbent dose on percentage removal of pb and cd ions is shown in figures 2(a) and (b) for a ph of 5.5. the percentage of lead ion removal increased from 31% to 98% when the adsorbent dose was increased from 0.5"10.0 g/l. cd adsorption was lower compared to pb, and the minimum dose of coir pith required for 98% cd removal was 10.0 mg/l solution. the number of adsorption sites and specific surface area increases with the weight of adsorbent, and, hence, results in a higher percent of metal removal at high dose. however, as shown in the figure. 2(b) amount of metal ions adsorbed per unit weight of adsorbent (q) decreases with the adsorbent dose. this shows that at higher dose the adsorbent is not fully utilized. journal of tropical forestry and environment vol. 01, no. 01 (2011) 36-47 39 3.3 effect of initial metal ion concentration figures. 3(a) and (b) show the percentage of ions removed as a function of time for a range of pb and cd ion concentrations for a ph of 5.the pb and cd ion removal percentages increased as the initial ion concentration decreased. at low ion concentrations, the ratio of surface active sites to total metal ions in the solution was high, and, hence, all metal ions may have interacted with the adsorbent and have been removed from the solution. however, the amount of metal adsorbed per unit weight of adsorbent, q, is higher at high concentrations. the values were 17, 23 and 25 for cd and 20, 38 and 52 mg/g for pb at 50 , 100 and 150 mg/l initial concentrations respectively. property mean particle size (mm) 513 surface area (m2/g) 1.56 pore size (ao) 45.2 bulk density (kg/m3) 116 true density (kg/m3) 799 figure 2: effect of adsorbent dose on cd and pb adsorption onto coirpith from 100 mg/l solution at 26 oc. amarasinghe /journal of tropical forestry and environment vol. 01, no. 01 (2011) 36-47 figure 1 (a) : electron microscopy (sem) of coir pith. 2.5 2.0 1.2 1.0 0.5 0.0 0 200 400 600 diameter (a0) d v( lo gd )x 10 0( cc /g ) 0 5 10 15 20 25 adsorbent dose (me/l) a ds or pt io n% 100 80 60 40 20 0 80 60 40 20 0 0 10 20 30 m g ad so rb ed /g o f ad so rb en t adsorbentdose (mg/l) figure 1(b):pore size distribution of coir pith. 40 figure 3: effect of initial solution concentration on adsorption of cd (a) and pb (b) onto coir pith, dose 2.5 g/l, 26 oc. 3.4 adsorption isotherms several equilibrium models have been developed to describe adsorption isotherm relationships (seader, 2006). the langmuir model was originally developed for adsorption of gases onto solids, and is based on the assumption that adsorption occurs on localized sites with no interaction between adsorbate molecules and maximum adsorption occurs when the surface is covered by a monolayer of adsorbate. for solid-liquid systems, the linear form of the isotherm can be expressed by the equation (1): )1( e eo e bc bcq q + = (1) .the freundlich isotherm model is an empirical model for adsorption, and is expressed as; n ee kcq /1= (2) where b = adsorption coefficient (l/mg). c e = the residual liquid phase concentration at equilibrium (mg/l). k = constants related to adsorption capacity n = constants related to adsorption intensity q e = the amount of metal adsorbed per unit weight of adsorbent (mg/g) at equilibrium q o = the amount of solute adsorbed per unit weight of adsorbent corresponding to complete coverage of available sites (mg/g). the experimental data were fitted to both langmuir and freundlich isotherms using linear regression of the linearized forms of eq. 1 and 2. the isotherm coefficients in equations (1) and (2), and the regression coefficients (r2), are given in table 2. the 1/n values for both pb and cd lie between zero and 1, thereby, indicating a favorable adsorption isotherm. overall, pb had a higher adsorption capacity as compared to cd. journal of tropical forestry and environment vol. 01, no. 01 (2011) 36-47 time (mins) 100 80 60 40 20 0 0 20 40 60 80 100 c d a ds or pt io n (% ) 100 80 60 40 20 0 p b a ds or pt io n (% ) time (mins) 50 mg/l 100 mg/l 150 mg/l 41 table 2: langmuir and freundlich isotherm data for adsorption of pb and cd onto coir pith at 26 °c. metal freundlich constants langmuir constants k 1/n r2 q o b r2 cd 4.91 0.4372 0.9161 25.83 0.1510 0.9866 pb 15.03 0.3845 0.8943 71.90 0.1774 0.9842 the results discussed, so far, indicate a higher adsorption of pb compared to cd for the experimental conditions under observation. this may be explained by the hydration enthalpy which is the energy that permits the detachment of h 2 o molecules from cations, and then reflects the easiness for the ion to interact with the functional groups on coir pith particles. the more a cation is hydrated, the stronger its hydration enthalpy, and the less it could interact with the adsorbent. hydration enthalpies of pb and cd are -1481 and -1807 kj/kg, respectively (www.science.uwaterloo.ca) which indicates a theoretical high affinity of pb cations to the adsorbent and, hence, higher removal of pb compared to cd. pb has shown higher adsoption capacities than several other heavy metal types such as cu, cd, ni, zn (amarasinghe, 2007, martin-dupoint, 2002, ricordal, 2001). 3.5 effect of solution ph figure 4 shows the percentage of metal ions adsorbed on to coir pith as a function ph. cd and pb adsorption show maximum removal in the ph range 5-7. at ph 2-3 range the adsorption is very low, and rapidly increases between ph 4-5. this phenomenon can be explained by the weakly acidic nature of surface functional groups of the coir pith. at low ph, acidic surface functional groups tend to be protonated, and, hence, do not significantly participate in ion exchange reaction due to strong competition of protons for those sites. these data are in agreement with the results obtained for other biomass materials such as coffee residues (boonamnuayvitaya, 2004), orange waste (dhakal, 2005), coca shells (meunier, 2003), sago waste (quek, 1998) and saw dust (sciban, 2006, shukla, 2002) by other workers. figure 4: effect of ph on adsorption of cd and pb onto coir pith, dose 2.5 g/l, 26 oc. at very high ph values (e.g., ph of 7), metal complex forms and results in the precipitation of metal salts, and, therefore, the metal removal may be due to this other mechanism in addition to adsorptive ion amarasinghe /journal of tropical forestry and environment vol. 01, no. 01 (2011) 36-47 a ds or pt io n (% ) 100 80 60 40 20 0 2 4 6 8 cd pb ph 42 exchange (aslam, 2004, gaikwad, 2004, sciban, 2006). hence, adsorption of cd and pb cations onto coir pith could be at optimum in the ph range 5-6. 3.6 adsorption kinetics adsorption kinetics controls the solute uptake rate which, in turn, controls the length of the mass transfer zone within a contactor, and (indirectly) affects the size of the adsorption equipment. our experimental results in figures 3(a) and (b) for coir pith show rapid initial adsorption rate followed by a slower rate. it is hypothesized that these results are due to the porous structure of the coir pith. specifically, larger open pores would be rapidly accessible with little diffusional constraints. however, there appears to be a fraction of exchange sites in surface regions with much smaller pores for which slow diffusion plays an important role. the results suggest that most of the exchange sites (e.g., 90%) appear to be accessible in the fast diffusion kinetic region, and that the slowly accessible sites are relatively minimal. several adsorption kinetic models have been developed, and widely used, to describe adsorption kinetics (ho, 1999, onganer, 1998, preetha, 2005, qadeer, 2005, uzun, 2000, horsfall, 2003). the lagregran pseudo-first-order model can be expressed as: )(1 qqk dt dq e −= (3) tkqqq ee 1)ln()ln( −=− (4) where q is the capacity at time (t), q e is the equilibrium capacity, and k 1 is the pseudo-first-order adsorptive rate constant. alternatively, the second-order model is expressed as: 2 2 )( qqk dt dq e −= (5) 2 2 1 ee qkq t q t += (6) where k 2 is the second-order rate constant. the initial adsorption rate (h) is equal to k 1 q e and k 2 q e 2 (mg g-1 min-1) for firstand second-order models, respectively. these models were used to analyze the nature of the adsorption kinetics for cd and pb on coconut coir pith. specifically, the results obtained for adsorption of cd and pb onto coir pith as function time were fitted to both eq. 4 (pseudo-first order) and eq. 6 (second order). the results showed that the second-order model, given by eq. 6. provides better correlation than pseudo-first-order model. the corresponding second-order kinetic parameters, and correlation coefficients, thus obtained are shown in table.3. experimentally determined sorption capacities shown in the last column of the table are in journal of tropical forestry and environment vol. 01, no. 01 (2011) 36-47 43 agreement with the equilibrium sorption capacities q, determined using second order model. pb shows higher initial adsorption rate (h) compared to cd for all concentrations. however, rate constant k, for cd is higher than pb except for 50 mg/l concentration. table 3: second order kinetic parameters for adsorption of pb and cd onto coir pith. metal solution h (mg g-1 k 2 (g mg-1 q pre (mg/g) r2 -q exp conc. min-1) min-1) (mg/g) (mg/l) cd 150 13.64 0.0288 25.57 0.9999 25.08 100 12.78 0.0238 23.15 0.9990 22.74 50 14.34 0.0462 17.60 1 17.39 pb 150 26.52 0.0093 53.19 1 51.82 100 22.17 0.0147 38.75 0.9999 37.99 50 20.24 0.0514 19.84 1 19.64 3.7 fixed bed adsorption breakthrough curves obtained from fixed-bed column operations for pb and cd adsorption onto coir pith from single metal ion solutions at 100 mg/l are shown in figure 5. typical ‘s’ shaped curves breakthough curves were obtained for all experiments. the area above the breakthrough curve is a measure of the bed capacity (bc). the average bed capacities for cd and pb were 18 and 54 mg/g, respectively. these results suggest that raw coir pith can be used as low cost adsorbent for removal of cd and pb from waste water. the above values can be compared with the model predictions based on batch experiments. for cd, model values predicted by the langmuir and freundlich models are 24 and 36, mg/g, respectively (for 100 mg/l aqueous equilibrium concentration). for pb, model values predicted by the langmuir and freundlich models are 68 and 88, mg/g, respectively (for 100 mg/l aqueous equilibrium concentration). bed capacities obtained by column experiments are lower than model predictions which can be due to following reasons. in batch experiments the mixture was shaken continuously and good interaction between the solid and solute was achieved. in the fixed bed, adsorbent is packed in the column and surface of the solid particles are in contact with each other and therefore results a less solid-solute interaction. further, liquid channeling which results in poor solid-metal ion contact and less residence time may occur in the column. therefore bed adsorption capacities are lower compared to batch operation. the bed depth service time (bdst) is a simple model for the prediction of adsorber performance (lee, 2000).the model proposes a relationship between bed depth, z, and the time taken for breakthrough to occur, and assumes that the adsorption rate is proportional to both the residual adsorbent capacity and the remaining adsorbate concentration. the linearised equation can be expressed as follows: amarasinghe /journal of tropical forestry and environment vol. 01, no. 01 (2011) 36-47 44 ⎟ ⎠ ⎞ ⎜ ⎝ ⎛ −−= 1ln 1 cb co kco z cov no t (7) where co, cb = initial and breakthrough metal ion concentrations (mg/l). k = adsorption rate constant (l/mg min). no = adsorptive capacity (mg/l). t = service time (min). v = linear flow rate of solution(m/min) z = bed height (m). the bed depth verses service time plots for cd and pb adsorption onto coir pith are shown in figure 7. breakthrough was assumed at 10% of the feed concentration. the results show that the bed depth service time were linear indicating the validity of bdst model for this system. bed capacity (n 0 ) and the adsorption rate constant (k) were calculated from the gradient and the intercept of the bdst plots. the computed n 0 and k values were 4921 mg/l (41 mg/g) and 0.00345 l/ mg min for pb and 2782 mg/l (23 mg/g) and 0.000919 l/mg min for cd, respectively. the bed capacities thus calculated are in agreement with the batch experimental results, and the values obtained from the breakthrough curve areas. jusoh et al.(2007) have tested adsorption of pb and cd onto granular activated carbon (size 850-100 mm for initial solution concentrations of 20 mg/l), which typically has a surface area around 500-600 m2/g and obtained n 0 and k values of 2308 mg/l and 0.00013 l/mg min for pb and 1552 mg/l and 0.00023 l/mg min for cd respectively. n 0 and k values obtained in this work are also in the same order of magnitude as the results obtained for ni adsorption onto tea waste (malkoc, 2006). these bdst model parameters can be useful in designing industrial adsorption units. figure 5: breakthrough curves for adsorption of pb and cd onto coir pith at various bed heights, 5.5 ml./min journal of tropical forestry and environment vol. 01, no. 01 (2011) 36-47 o ut le t p b c on ce nt ra io n (m g/ l ) 100 80 60 40 20 0 0 50 100 150 200 5 cm 10 cm 18 cm 12 cm no of bed volumes 100 80 60 40 20 0 0 50 100 150 200 5 cm 10 cm 18 cm 12 cm no of bed volumes o ut le t p b c on ce nt ra io n (m g/ l ) 45 the adsorption capacities achieved for a specific situation will depend on the operating conditions, the source of coir pith, the pretreatments given, and other factors. coir pith used for this work was not treated chemically or thermally. chemical or thermal treatments of adsorbents could be used to enhance the adsorptive properties of coir pith. however, these treatments are costly, add complexity to the process, and could add other chemicals to water. however, the results of the present work show raw coir pith has a good adsorption capacity for pb and cd, and may be suitable as an alternative to higher cost adsorbents. 4. conclusions results showed that coir pith is an effective and inexpensive adsorbent for cadmium and lead from aqueous solutions. the adsorption capacity strongly depends on the solution to adsorbent ratio used and the solution ph. adsorption was maximum at solution ph values above 5. adsorption is fast with 90% of the adsorption occurring within the first 10 min. kinetic data fits to the second-order model. the equilibrium isotherms can be represented by both the freundlich and langmuir models. pb showed higher adsorption capacity and affinity compared to cd under all the experimental conditions studied. fixed-bed column results show that data fits to the linear bdst model. computed bed capacity (no) and the bdst adsorption rate constant (k) were 4921 mg/l and 0.00345 l/mg min for pb and 2782 mg/ l and 0.000919 l/mg min for cd respectively. acknowledgements author wishes to thank sri lanka-united states fulbright commission for providing fellowship. the support from professors j. raper, c. adams and d. ludlow enabling to conduct experiments at university of missouri-rolla, usa is greatly acknowledged. 300 250 200 150 100 50 0 b re ak th ro ug h ti m e, t ( m in s) 0 0.05 0.1 0.15 0.2 bed height z (m) pb cd fig 7: bdst plots for cd and pb (eqn 7) y = 1581x 6.360 r2 = 0.999 y = 894.8x 23.91 r2 = 0.963 amarasinghe /journal of tropical forestry and environment vol. 01, no. 01 (2011) 36-47 46 references amarasinghe b.m.w.p.k., gangodavilage n., 2005, adsorbents from waste biomass: production and application, 7th world congress of chemical eng., glasgow, july.10-14. amarasinghe b.m.w.p.k. and williams r.a., 2007, tea waste as an adsorbent for cu and pb removal from wastewater, chem. eng. j., 132 (2007) 299-309. aslam, m.m., hassen i., malik, m. and martin, a., 2004, removal of copper from industrial effluent by adsorption with economically viable material, ejeafche,3 (2),issn 1579-4377. babu, b.v. and ramakrishnan, v., 2003, ranking of adsorbents based on method of preparation and isotherm fitting, proceedings of international symposium & 56th annual session of iiche, (chemcon), bhubaneswar, december 19-22. baig, t.h., garcia, a.e., tiemann, k.j., and gardea-torresdey, j.l., 1999, adsorption of heavy metal ions by the biomass of solanum elaeagnifolium (silver leaf night-shade), proceedings of the hazardous waste research conference, st louis, missouri, may 24-27, 131-142. boonamnuayvitaya, v., chaiya, c., tanthapanichakoon, w. and jarudilikkul, s., 2004, removal of heavy metals by adsorbent prepared from pyrolyzed coffee residues and clay, separation and purification technology, 35, 11-22. chuah t.g., jumasiah, a., azni i., katayon s., thomas choong, s.y., 2005, rice husk as a potentially low-cost biosorbent for heavy metal and dye removal: an overview, desalination, 175, 305-316. conrad, k, and hansen, h, c., b., 2007, sorption of zinc and lead on coir, bioresource technol., 98(1), 89-97. corbitt r.a., standard hand book of environmental engineering, 2nd edition, mcgrawhill, 1999. dhakal, r. p., ghimire, k.n., and inoue, k., 2005, adsorptive separation of heavy metal from an aquatic environment using orange waste, hydromettalurgy, 79, 182-190. gaikwad, r.w., 2004, removal of cd(ii) fom aqueous solution by activated charcoal derived from coconul shell, ejeaf. ho, y.s., and mckay, g., 1999, pseudo-second order model for sorption processes, process biochemistry, 34, 451-465. horsfall, m. and a. a. abia, sorption of cadmium(ii) and zinc(ii) ions from aqueous solutions by cassava waste biomass (manihot sculenta cranz), water research, volume 37, issue 20 , december 2003, pages 4913-4923. jusoh, a., shiung, l.s., ali, n. and noor, m.j.m.m., 2007, a simulation study of the removal efficiency of granular activated carbon on cadmium and lead, desalination, 206, 9-16. lee v.k.c., porter j.f. and mckay, g., 2000, developemnt of fixed bed adsorber correlation models, ind. eng.,chem. res., 39(7), 2427-2433. macedo j.d,s., costa n., almeida, l, vieira e., cestari a., gimenez i., carreno, n. and barreto l., 2006, kinetic and calorimetraic study of the adsorption of dyes on mesoporous activated carbon prepared from coconut coir dust, j. of colloid and interface sci., 298, 515-522. malkoc e. and nutoglu, y., 2006, removal of ni(ii) ions from aqueous solutions using waste of tea factory: adsorption on a fixed –bed column, j. of hazardous materials, b135, 328-336. malkoc, e. and nutoglu, y., 2005, investigation of nickel ii removal from aqueous solution using factory waste, j. of hazardous materials, b127, 120-128. journal of tropical forestry and environment vol. 01, no. 01 (2011) 36-47 47 martin-dupoint f. et.al., 2002, heavy metal adsorption by crude coniferous barks: a modelling study, j. environ. sci. health, a37(6), 1063-1073. meunier, n. et.al., 2003, lead removal from acidic solutions by sorption on coca shells: effect of some parmeters, j. of env. eng. @ asce, august, 693-698. namsivayam, c. and sangeetha, d., 2006, recycling of agricultural waste, coir pith : removal of anions, heavy metals, organics and dyes from water by adsorption onto zncl 2 activated coir pith carbon., j. of hazardous materials, b135, 449-452. onganer, y. and temur, c., 1998, adsorption dynamics of fe(iii) from aqueous solutions onto activated carbon, j. of colloid & interface science, 205, 241-244. palma g., freer, j. and baeza, j., 2003, removal of metal ions by modified pinus radiata bark and tannins from water solutions , water research , 37,20, 4974-4980. preetha, b. and viruthagiri, t., 2005, biosorption of zinc(ii) by rhizopus arrhizus: equilibrium and kinetic modelling, african j. of biotechnology, 4(6), 506-508. qadeer, r and akhtar, s., 2005, kinetics study of lead ion adsorption on active carbon, turk j. chem, 29, 95-99. quek, s.y., wase, d.a.j. and forster, c.f., 1998, the use of sago waste for the sorption of lead and copper, water sa, 24(3), 251-256. ricordel, s. et. al., 2001, heavy metals removal by adsorption onto peanut husks carbon: characterization, kinetic study and modelling, separation and purification technology, 24, 389-401. santhy k. and selvapathy p., 2006, removal of reactive dyes from wastewater by adsorption on coir pith activated carbon, bioresource technol., 97, 1329-1336. sciban, m. and klasnja, 2004, wood sawdust and wood originate materials as adsorbents for heavy metal ions, european j. of wood and wood products, 62 (1),69-73. seader, j.d. and henly, e.j., 2006, separation process priniples, 2nd edition, john wiley and sons, inc.usa. shukla a., zhange y., dubey p., margrave j.l. and shukla s.s., 2002, the role of saw dust in the removal of unwanted materials from water, j. of hazardous materials, b95, 137-152. shukla s.r. and pai r.s., 2005, comparison of pb(ii) uptake by coir and dye loaded coir fibres in a fixed bed column, b125, 147-153. shukla, s.r., pai r.s., and shendarkar a.d., 2006, adsorption of ni(ii), zn(ii) and fe(ii) on modified coir fibers, separation and purification technology, 47(3), 141-147. uzun, i. and guzel, f., 2000, adsorption of some heavy metal ions from aqueous solution by activated carbon and comparison of percent adsorption results of activated carbon with those of some other adsorbents, turk j. chem., 24, 291-297. amarasinghe /journal of tropical forestry and environment vol. 01, no. 01 (2011) 36-47 chapter 6 56 journal of tropical forestry and environment vol. 01, no. 01 (2011) 56-70 estimation of above ground tree biomass and carbon of pinus caribaea (morelet) s.m.c.u.p. subasinghe*, g.b. munasinghe department of forestry and environmental science university of sri jayewardenepura nugegoda, sri lanka date received: 09-05-2011 date accepted: 02-10-2011 abstract forests in sri lanka contribute to the mitigation of global climate change through sequestrating a net amount of carbon dioxide and also maintaining carbon stocks as forest biomass. this study was conducted using an empirical method to understand the biomass and stored carbon by forest plantations in sri lanka. further, in this study, the possibility of predicting the above ground tree biomass and carbon of pinus caribaea (morelet) was investigated. a 27 year old p. caribaea plantation was selected from the low country wet zone in sri lanka and the data were collected using 0.05 ha sample plots. without felling trees, a core sample was obtained from the stem and biomass and carbon of that sample was used to estimate the stem biomass and carbon through volume measurements. the canopy biomass and carbon were estimated using samples of primary, secondary and tertiary branches and leaves. the total above ground tree biomass and carbon were estimated by adding the stem and canopy values together. it was found that, for 27 year old p. caribaea, the average above ground tree biomass was 368.9 kg and the carbon was 215.9 kg which is 58.5% from the biomass. the amount of carbon in the canopy was 64.5% from the canopy dry mass. the carbon percentages of the primary, secondary and tertiary branches and leaves were 61.7, 59.1 and 79.6 respectively. the total above ground tree carbon for a 27 year old p. caribaea plantation was 103.6 t ha-1. then regression models were developed to identify the relationships of biomass and carbon with stem volume. a relationship between biomass and carbon was also developed for the selected species. finally, mathematical models were developed to predict biomass and carbon using some other tree variables such as diameter and height, without felling the trees. *correspondence: e-mail upul.forestry@gmail.com tel: 00 94 11 2804685 fax: 00 94 11 2802914 issn 2235-9370 print/ issn 2235-9362 online ©2011 university of sri jayewardenepura 57 1. introduction atmospheric carbon dioxide (co 2 ) has increased significantly in the recent decades, with the major contributing factor being the combustion of fossil fuels in the production of energy and the second factor being land use practices (e.g., deforestation) that reduce the stock of carbon held in forest and soils (sedjo, et al., 1997, fao, 2002). the greenhouse effect is the result of the increase in the atmospheric temperature caused by the rapid increase in the concentration of atmospheric carbon dioxide (william, 1995). atmospheric co 2 is directly linked to terrestrial ecosystems through the global carbon cycle. green plants take up atmospheric co 2 and convert it to cellulose and other organic compounds. many of these compounds such as wood and some soil organic compounds are relatively stable, and maintain the carbon in inert form for many years, until the carbon is once again released in gaseous form due to the biological respiration or combustion (sedjo, et al., 1997). the high rates of deforestation in the tropics, especially during 1980s, caused the overall negative carbon exchange between the forests and atmosphere. at the beginning of 1980s, the estimated accumulation of carbon in recovering tropical landscapes which had previously been disturbed was roughly equal to the net carbon emission due to tropical deforestation and associated burning (lugo and brown, 1992). green plants remove co 2 from the atmosphere through photosynthesis. the carbon is stored in the foliage, stems, and root systems. due to the long lifespan of most of the trees and their relatively larger sizes, trees and forests act as storehouses of carbon (william, 1995). the world forests have been estimated to contain up to 80% of all above ground terrestrial carbon and approximately 40% of all below ground terrestrial carbon (soil, litter and roots). approximately 37% of this carbon is stored in low latitude (tropical) forests, 14% in mid latitude (temperate) forests and 49% in high latitude forests (dixon, et al., 1994). forest plantations received considerable publicity, particularly in the southern hemisphere, where high biomass increment rates can be received. a number of restrictions can be identified that limit the availability of suitable lands for afforestation, particularly when suggested for such a large-scale purpose (kohlmaier, et al., 1998). pinus caribaea is one of the commonest forest plantation species was introduced to sri lanka for the rapid rehabilitation of the deforested and degraded lands in the wet zone and the hilly areas in the intermediate zone. in the year 2000, sri lanka forest department maintained a 16,589.3 ha of pinus caribaea and p. patula plantations (gunathilake and palamakumbura, 2001) which are approximately 0.25% of the total land area. almost all the pine plantations were established in sri lanka within a short period of time in 1970s. therefore, due to the mature age of those planted trees, it is important to know the amounts of carbon trapped in the stem and branches and to predict those values using some other easily measurable tree variables such as diameter and height. the objectives of this study were: (i) estimation of above ground volume, biomass and carbon amount for p. caribaea plantations; and (ii) construction of mathematical models to predict above ground tree carbon from various explanatory variables that are easily measurable. subasinghe & munasinghe /journal of tropical forestry and environment vol. 01, no. 01 (2011) 56-70 58 2. methodology due to the recent interests regarding tree planting and maintenance as carbon sinks, this study was focused on a selected pinus caribaea (morelet) plantation in sri lanka in order to predict the stored carbon in above ground tree parts and to identify the relationship between other tree variables such as biomass and volume so that in future it would not be necessary to carry out destructive sampling biomass and carbon estimations. 2.1 study area for this study, a 27 year old even aged pinus caribaea plantation was selected from the southern part of sri lanka. this 25 ha population is located between n 06o20/ – 06o22/ to e 80o10/ – 80o12/ in kalutara administrative district in the low country wet zone. the annual rainfall in the area is over 4,000 mm and the average temperature is between 27 – 28.50c. 2.2 sampling being there were slight geographical variations in the selected forest, the entire even-aged plantation was divided into three strata i.e., valley, slope and ridge top and two 0.05 ha circular samples were randomly selected from each stratum for data collection. 2.3 measurements i. volume estimation newton’s formula (philip, 1994; subasinghe, 1998) was used to estimate the precise stem volumes for this study. standing trees were divided into sections less than 3 m and base, top and mid diameters and length of each section were accurately measured. then the volume for each section was separately estimated using newton’s formula. the top most section was assumed as a cone. in order to calculate the total stem volume, the section volumes were added together as shown in equation (1). fs vvv +σ= (1) where: v = total stem volume, m3 v f = volume of the final section (cone), m3 v s = volume of the sth section, m3 ii. estimation of stem biomass and carbon early studies conducted for the same species indicated that the biomass per unit volume (wood density) is not significantly different along the stem from the bottom to the top (haripriya, 2003). therefore, it was decided to use only one core sample from the tree stem for the analysis of carbon and biomass. those core samples were extracted at the breast height and green volume and oven dry weight were measured. then they were oven-dried at 1050c until a constant weight was achieved. the dry weight of the entire main stem was then calculated using equation (2). journal of tropical forestry and environment vol. 01, no. 01 (2011) 56-70 59 c c s v vw w × = (2) where: v c = green volume of the core sample, m3 w c = dry weight of the core sample, kg w s = total dry mass of the stem, kg the available carbon was determined by using the walkley and black method for the dried samples and it was converted to the entire stem using equation (3). v v c c c c s ×= (3) where: c c = c amount of the core, kg c s = c amount of the stem, kg iii. estimation of canopy biomass and carbon the canopy of pinus caribaea is conical in shape. first the total number of branches which formed the canopy was counted. then the canopy was divided into three parts i.e., top, middle and bottom and one branch representing each section was selected as a sample. each selected branch was separated into three parts as primary, secondary and tertiary. the dry mass of those samples were determined by placing them in an oven at 1050c until those achieved a constant weight. first the values of three selected branches (top, mid and bottom) were added and averaged to estimate the total canopy biomass. then that value was multiplied by number of branches in order to estimate the canopy biomass. amount of c in primary, secondary, tertiary branches and leaves were estimated using equation (4) and using those values in equation (5), total carbon amount was estimated. lb lb lb lb w s x c , , , , = (4) ltbsbpbcanopy ccccc +++= (5) where: c canopy = carbon amount in canopy, kg c b,l = c amount in iry, iiry, iiiry branches or leaves, kg c l = leaf c amount, kg c pb = c in primary branches, kg c sb = c in secondary branches, kg subasinghe & munasinghe /journal of tropical forestry and environment vol. 01, no. 01 (2011) 56-70 60 c tb = c in tertiary branches, kg s b,l = sample weight of iry, iiry, iiiry branches or leaves w b,l = dry weight of iry, iiry, iiiry branches or leaves in the canopy, kg x b,l = c in the sample of iry, iiry, iiiry branches or leaves in the canopy, kg iv. total above ground carbon total above ground carbon per each tree was estimated by adding the stem carbon and canopy carbon values together. v. amount of above ground tree c in one hectare land of p. caribaea after estimation of the above ground carbon amount for p caribaea in each sample plot, the carbon amount stored in stems and canopies in a unit area (one hectare) of the forest was estimated using equation (6). na c plotς= c (6) where: a = plot area, ha c = carbon stored in stems and canopies per ha, kg c plot = above ground tree carbon per plot n = number of plots vi. establishment of relationships in order to identify the relationship between above ground carbon and biomass of the selected species and to predict the available carbon using the tree variables that can be measured easily, regression analysis was performed as follows. stem carbon vs stem biomass stem carbon vs stem volume stem carbon vs diameter at breast height (dbh) stem carbon vs. dbh and total height above ground tree carbon vs. above ground tree biomass above ground tree carbon vs stem volume above ground tree carbon vs dbh validating of identified models were conducted by performing appropriate statistical tests and be investigating residuals. journal of tropical forestry and environment vol. 01, no. 01 (2011) 56-70 61 3. results 3.1 biomass and carbon of the canopy carbon compositions of the various parts of the canopy of 27 year old p. caribaea found to be different (figure 1) depending on the size and the storage capacity. figure 1: estimated biomass and carbon values and mean confidence intervals of the various parts of tree canopy. biomass and carbon were the highest in primary and secondary branches in the canopy. the average total canopy biomass is 35.4 kg while the average canopy carbon is 22.9 kg which is 64.5%. the carbon percentages of i ry and ii ry branches and iii ry branches and leaves are 61.7%, 59.1% and 79.6% respectively from biomass values (figure 2). when 1-way anova was performed, biomass of i ry and ii ry branches were significantly different from that of other two parts of the canopy (f value = 13.73 and p value = 0.000 at 95% probability level). similar results were also observed for canopy carbon values (f value = 12.65 and p value = 0.000 at 95% probability level). 3.2 biomass and carbon in the stem the average biomass per individual p. caribaea stem in the selected forest was 333.5 kg while the carbon amount wais 193.0 kg (figure 3). therefore the carbon content is 57.6% of the stem biomass (figure 2). 3.3 above ground biomass and above ground carbon per tree distribution of the amounts of above ground carbon and biomass for different tree parts are given in figure 2. when compared with the mature tree stem of p. caribaea, biomass and carbon of the canopy become very low. the reason is that the conifers do not produce large crowns, and the number of leaves in the canopy is lower when compared to the most of broad-leaf species. biomass carbon iry & llry branches illry branches leaves w ei gh t, k g 60 50 40 30 20 10 0 subasinghe & munasinghe /journal of tropical forestry and environment vol. 01, no. 01 (2011) 56-70 62 figure 2: carbon percentages from the respective biomass values and mean confidence intervals of different parts of p. caribaea. the average total above ground biomass per tree of the selected species was 368.9 kg while the stored carbon amount was 215.9 kg (figure 2) which is 58.5% from the dry mass. according to the twosample t test, biomass and carbon values for stem and canopy indicated significant differences (t values = 4.11 and 4.08 and p values = 0.003 and 0.003 respectively for biomass and carbon). figure 3 illustrates carbon percentages with respect to biomass values of different parts of p. caribaea trees. 1-way anova was performed for those values to identify the differences of carbon percentages (f value = 83.39 and p value = 0.000 at 95% probability level). however, according to the further analysis, it was proved that only leaf carbon percentage was significantly different from the carbon percentages in rest of the parts of the tree. figure 3: average above ground biomass and carbon values and mean confidence intervals for p. caribaea biomass carbon stem canopy w ei gh t, k g 600 500 400 300 200 100 0 c p er ce nt ag e 150 125 100 75 50 25 0 iry & llry branches illry branches leavesstem journal of tropical forestry and environment vol. 01, no. 01 (2011) 56-70 63 3.4 amount of carbon content in yagirala pine forest and in pine forests in sri lanka it was found that above ground carbon amount per tree is 215.9 kg for the selected species. according to the initial measurements, an average number of pine trees per hectare in the yagirala forest was 480 and therefore the amount of above ground c is 103.632 t ha-1. all pine plantations were established in sri lanka approximately at the same time and therefore it can be concluded that all the pine plantations are similar in age. if it is assumed that due to the application of the same treatments, the number of available trees per hectare is similar, the amount of above ground carbon available in all the pine plantations in sri lanka is 1,719,183.34 t, because the area covered by those pine plantations is 16,589.3 ha (bandaratillake, 2001). 3.5 relationship of above ground carbon with other tree variables regression analyses was carried out to build the mathematical relationships of carbon with other selected variables. in order to find the best models, other than the original form, biologically acceptable transformations i.e., square, square root, logarithmic and reciprocal were also used for both response and explanatory variables. 3.5.1 stem carbon vs stem mass initially five models were identified to observe the relationship between stem carbon and stem mass from twenty five possible combinations of equations. out of those equations, ss mc 711.0689.0 += had the best relationship. further analysis of this model proved that the intercept was not significant (p value = 0.165). therefore it was removed from the model and re-fitted to obtain equation (7). r 2 of model (7) was 95.0% (figure 4). ss mc 755.0= (7) where: c s = carbon trapped in the stem biomass, kg m s = dry mass of the pine stem, kg 3.5.2 stem carbon vs stem volume from stem carbon and stem volume, another twenty five relationships were initially developed. among those models, the best model was ss vc 7.17081.0 += , which had a non-significant intercept (p value = 0.897). moreover, when volume is 0, carbon value should also be 0 as it cannot exist without a volume. therefore equation (8) estimated by re-fitting the above model was selected as the best relationship (figure 5) between carbon and stem volume (r 2 = 92.7%). ss vc 8.17= (8) where: v s = stem volume, m3 subasinghe & munasinghe /journal of tropical forestry and environment vol. 01, no. 01 (2011) 56-70 64 figure 4: observed stem carbon values and the fitted line for the selected model (7) to predict stem carbon (c s ) from stem biomass (m s ), r2 = 95.0% figure 5:observed stem carbon values and the fitted line for the selected model (8) to predict stem carbon (cs) from stem volume (vs), r2 = 92.7% 3.5.3 stem carbon vs diameter at breast height (dbh) for the relationships (7) and (8), the selected explanatory variables are practically difficult to measure. therefore, in order to simplify the field work, it was decided to build a model to predict the stem carbon with easily measurable variables such as diameter and height. another twenty five models were initially identified for the relationship between stem carbon and diameter at breast height. dcs 562.0684.1 +−= was the best model among the initially selected (s te m c ar bo n) 1/ 2 25.0 20.0 15.0 10.0 5.0 0.0 5.0 10.0 15.0 20.0 25.0 30.0 (stem mass)1/2 (c 5 )1/2 = 0.755 (m 5 )1/2 (s te m c ar bo n) 1/ 2 25.0 20.0 15.0 10.0 5.0 0.0 0.20 0.40 0.60 0.80 1.00 1.20 (c 5 )1/2 = 17.8 (v 5 )1/2 (s te m c ar bo n) 1/ 2 (stem volume)1/2 journal of tropical forestry and environment vol. 01, no. 01 (2011) 56-70 65 ones. its intercept was not significant (p value = 0.068) and therefore the parameters were reestimated without the intercept to obtain model (9) which had the r 2 of 89.4%. figure 6 illustrates the distribution of the fitted line of model (9). dcs 492.0= (9) where: d = tree diameter at breast height, cm figure 6: observed stem carbon values and the fitted line for the selected model (9) to predict stem carbon (c s ) from diameter at breast height (d), r 2 = 89.4%. 3.5.4 stem carbon vs dbh and total height the intention of adding total tree height as an additional explanatory variable was tested to identify the possibility of developing a more accurate model than model (9). the selected best model was hdcs 72.2)/1(22393.8 +−= which had a non-significant intercept (p value = 0.115). model (10) shows the re-fitted model without the intercept. its r 2 value (87.0%) was comparatively low though the standard residual distribution was reasonably good. due to this reason, it was decided to recommend model (9) which uses only the dbh as the only explanatory variable for the field use. hdcs 30.4)/1(188 +−= (10) where: h = total tree height, m 3.6 construction of relationships to predict above ground tree carbon from the regression analyses carried out to build models to predict above ground tree carbon (carbon of stem, branches and leaves), the identified models are described below. (s te m c ar bo n) 1/ 2 20.0 15.0 10.0 5.0 0.0 10.0 20.0 30.0 40.0 diameter (bh) (c 5 )1.2 = 0.492d subasinghe & munasinghe /journal of tropical forestry and environment vol. 01, no. 01 (2011) 56-70 66 3.6.1 above ground tree carbon vs above ground tree biomass from the initially developed twenty five models, the selected model (11) indicated a good fit (figure 7) with a high r 2 value of 97.7%. its original form was agag mc 744.0624.0 += and the intercept was not significant (p value = 0.420). agag mc 777.0= (11) where: c ag = above ground tree carbon, kg m ag = above ground biomass, kg the structure of this model was similar to that of the stem carbon prediction model from stem biomass model (7). however, the regression coefficient associated with agm for the model (11) is slightly higher than that of model (7). figure 7: observed above ground tree carbon values and the fitted line for the selected model (11) to predict above ground tree carbon (c ag ) from above ground tree biomass (m ag ), r2 = 97.7% 3.6.2 above ground tree carbon vs stem volume similar to the above procedures, above ground tree carbon was regressed against the stem volume and the selected model was given in equation (12). the best equation had non-transformed variables and the r 2 of 96.0%. its standard residual distribution is given in figure 8. its original model was vc ag 35208.9 += and the intercept was not significant (p value = 0.618). (a bo ve g ro un d tr ee ca rb on )1 /2 25.0 20.0 15.0 10.0 5.0 0.0 5.00 10.00 15.00 20.00 25.00 30.00 35.00 (above ground tree mass)1/2 (c ag )1.2 = 0.777 (m ag )1/2 journal of tropical forestry and environment vol. 01, no. 01 (2011) 56-70 67 vc ag 364= (12) where: v = stem volume, m3 figure 8: standard residual distribution for model (12). 3.6.3 above ground tree carbon vs dbh models (11) and (12) identify the relationship of above ground tree carbon of p. caribaea with above ground biomass stem volume. however, for the practical use, both models are impossible to use due to the difficulty of measuring the explanatory variables, i.e., tree mass and tree volume. therefore, as a solution, another model was developed between above ground tree carbon and dbh which is easier to measure in the field. it (13) had r 2 of 92.7% and also had a good standard residual distribution (figure 10). 2271.0 dcag = (13) figure 9: standard residual distribution for model (13). s ta nd ar d re si du al s 2.0 1.0 0.0 -1.0 -2.0 0 100 200 300 400 500 fitted c s ta nd ar d re si du al s 2.0 1.0 0.0 -1.0 -2.0 100 200 300 400 500 600 fitted c subasinghe & munasinghe /journal of tropical forestry and environment vol. 01, no. 01 (2011) 56-70 68 the structure of the model 13 is different from the model developed to predict the stem carbon from dbh (model (10)). although the explanatory variable (dbh), is included in non-transformed from for both models, the response variable stem carbon for the model (10) is in square root form and above ground carbon for the model (13) is in non-transformed form. 4. discussion inventory data have often been used to estimate the biomass and carbon contents in tropical forests (brown and lugo, 1992) and in europe (kauppi et al., 1992). most of such models were developed using dbh and height which are the common inventory data available in many countries (segura and kanninen, 2005). considering the error that can be occurred by measuring various individual height terms, segura and kanninen (2005) recommended to develop models using dbh as the single explanatory variable to predict the tree carbon. emission of carbon dioxide and other green house gases are increasing due to human activities. the major carbon dioxide removing pathway from the lower atmosphere is the photosynthesis (leaves, branches, stem and roots) which store co 2 as carbohydrates. the stored c can be lost due to the leaf fall. however, pinus is not a deciduous species and therefore the number of leaves in the canopy is maintained as a constant. therefore, that loss is regained by the new leaves. according to dixon et al., (1994) the ration of total dry biomass to carbon is approximately 2:1. the c content of an undisturbed tropical moist forest has a high value, i.e., 250 t ha-1 of standing above ground biomass. however, this study found that more than 50% from the biomass is carbon for p. caribaea. according to this study, the estimated above ground tree carbon content of the pine plantations in sri lanka is 103.63 t ha-1. when compared with tropical forest storage of carbon, that amount is low in mature pine monocultures. in 1983, olsen et al., published average above ground stored carbon values per hectare by various vegetation communities. when compared the values obtained in this study with the above values for p. caribaea, the values estimated for this study is much higher. according to schroeder (1991), the storage of above ground carbon was 59 t ha-1 of pinus caribaea within 15 year rotation age. the difference between the values obtained in this study his findings could be due to the difference of age and planting densities. in this study, c prediction models were built from the selected explanatory variables to identify the pattern of relationships and best models for p. caribaea in sri lanka. in order to identify the best suitable models, the variables used were transformed into biologically acceptable forms i.e., square root, square, logarithmic and reciprocal following the work done by subasinghe in 1998. the best models were selected depending on the r2 values and the standard residual distribution. the advantage of using the selected methodology for this study is that, it is not necessary to carry out the destructive sampling. similar studies were conducted for forest biomass estimations in the past by beets et al., (1999); chhetri, (1999); keller et al., (2001); ketterings et al., (2001); segura and kanninen (2005). this study had two main objectives, i.e., to identify the above ground biomass and carbon values for the selected species and to predict the above ground tree carbon from the tree variables which are not journal of tropical forestry and environment vol. 01, no. 01 (2011) 56-70 69 difficult to measure. by fulfilling the second objective, it was possible to recommend a method to estimate the above ground tree carbon for p. caribaea, so that the destructive sampling is not necessary in the future estimations. ketterings et al., (2001) also proved that the destructive sampling is not necessary for biomass studies. therefore the results of this study can be applied when estimating the ecosystem biomasses in large scale using the remotely sensed data. 5. conclusion carbon storage of p. caribaea in yagirala forest reserve is 103 mt ha-1 and for the whole country it is approximately 1,719,183 mt. this value was calculated assuming that all pine plantations contain the same number of trees per hectare and had similar growth rates. it is possible to predict the amount of above ground carbon stored in the selected species using easily measurable variables such as diameter at breast height. therefore complex and time-taking measurements are not needed in future for this purpose. limitation of the present study data collected from a single plantation was used in this study assuming that the age and the management treatments were similar for all p. caribaea plantations in sri lanka. however, it is a limitation in the present study and therefore it is recommended to validate the results with the data collected from several plantations in the future. references bandaratillake, h.m., 2001. administration report of the conservator of forests in sri lanka for the year 2000. forest department, sri lanka beets, p.n., robertson, k.a., ford-robertson, j.b., gorden, j. and maclaren, j.p., 2000. description and validation of c change: a model for simulating carbon content in managed pinus radiata stands. new zealand journal of forestry research 29 (3): 409-427 brown, s. and lugo, a.e., 1992. above ground estimates for tropical moist forests of the brazilian amazon. interciencia 17(1): 8-27 chhetri, d.b.k., 1999. comparison of forest biomass across a human-induced disturbance gradient in nepal’s schima-castanopsis forests. journal of sustainable forestry 9(3-4): 69-82 dixon, r.k., brown, s., hougton, r.a., solomon, a.m., trexler, m.s. and wisniewski, j., 1994. carbon pools and flux of global forest ecosystems, science 263: 185-190 fao, 2002. an international journal of forestry and forest industry, fao forestry paper 2002, vol 53., rome, italy gunathilake, r.p.s.i.k. and palambakumbura, s.c., 2001. utility value of pine resource in sri lanka, forest department, sri lanka. haripriya, a.m.r., 2003. relationship between individual stem volume and biomass for pinus caribaea in the yagirala forest reserve, department of forestry and environmental science, university of sri jayewardenepura, sri lanka subasinghe & munasinghe /journal of tropical forestry and environment vol. 01, no. 01 (2011) 56-70 70 lugo, a.e. and brown, s., 1992. tropical forests as sinks of atmospheric carbon, forest ecoogy and management 54: 239-255. kauupi, p.e., mielikainen, k, and kuusela, k., 1992. biomass and carbon budget of european forests, 1971 to 1990. science 256(5053): 70-74 keller, m., palace, m. and hurtt, g., 2001. biomass estimation in the tapajos national forest, brazil. examination of sampling and allometric uncertainties. forest ecology and management 154 (3): 371-382 ketterings, q.m., coe, r., noordwijk, m. van., ambagau, y., palm c.a. and van noordwijk, m., 2001. reducing uncertainty in the use of allometric biomass equations for predicting above-ground tree biomass in mixed secondary forests. forest ecology and management 146 (1-3): 199-209 kohlmaier, g.h., weber, m. and hougton, r.a., 1998. carbon dioxide, mitigation in forestry and wood industry, springer-verleg, new york olsen, j.s., watt, j.a. and allison, l.j., 1983. carbon in live vegetation of the major world ecosystems, us department of energy, oak national laboratory, tennessee, usa philip, m.s., 1994. measuring trees and forests, 2nd ed. cambridge university press, uk sedjo, r.a., wisniewski, j, and sampson, r.n., 1997. economics of carbon sequestration in forestry, lewis publishers, boca raton segura, m. and kanninen, m., 2005. allometric models for tree volume and total above ground biomass in a tropical humid forest in costa rica. biotropica 37(1): 2-8 schroeder, p., 1991. carbon storage potential of short rotation tropical tree plantations, epa, corvallis region, usa subasinghe, s.m.c.u.p., 1998. construction of growth models for pinus nigra var. maritima (ait.) melville (corsican pine) in great britain, ph.d. thesis, university of wales bangor, uk william, m.c., 1995. climatic change, forest and forest management, fao forestry paper no. 126, food and agricultural organization, rome journal of tropical forestry and environment vol. 01, no. 01 (2011) 56-70 chandrathilake /journal of tropical forestry and environment vol. 12, no. 02 (2022) 1-9 correspondence: thilakawansha@sjp.ac.lk issn 2235-9362 online ©2022 university of sri jayewardenepura 1 feature article the need of ecohydrological research in tropical forests for healthy watersheds g.g.t. chandrathilake 1department of forestry and environmental science, university of sri jayewardenepura, nugegoda, sri lanka thilakawansha@sjp.ac.lk abstract tropical forests play a critical role in providing clean water and maintaining healthy watersheds, yet they face numerous threats such as deforestation, land use change, and climate change. to address these challenges, there is a growing need for ecohydrological research that can inform land use planning and management strategies for healthy watersheds. ecohydrology is an emerging science that seeks to understand the functional interactions between hydrology and biota. it quantifies and explains the relationships between hydrological processes and biotic dynamics as well as linkages among upland, riparian, and aquatic components on a watershed scale. however, most of the ecohydrological studies have been concentrated on temperate regions, and for tropical regions, such studies are lacking. this article argues that there is a high time to launch research for identifying critical ecohydrological functions and driving forces that regulate the quality and quantity of water, and their role in providing water-based ecosystem services in tropical watersheds. the article outlines the main challenges facing tropical forests and watersheds, and highlights the importance of interdisciplinary collaboration and long-term monitoring for effective ecohydrological research. it also provides examples of successful ecohydrological research projects in tropical forests, and discusses the potential benefits of investing in ecohydrological research for tropical forest conservation and watershed management. overall, this article emphasizes the importance of ecohydrological research in tropical forests for healthy watersheds and calls for more attention and resources to be devoted to this field. keywords: ecohydrology, tropical forests, watersheds, water resource management, ecosystem services 1. introduction tropical forests play a critical role in providing essential ecosystem services, including carbon sequestration, biodiversity conservation, and water regulation (chandrathilake, 2019; chazdon et al., 2016; ewers et al., 2015; gibbs et al., 2010). among these services, the provision of clean water for human consumption and ecosystem health is perhaps the most vital. healthy watersheds are essential for the sustainable management of water resources, as they help regulate water quantity and quality (cerda et al., 2018; keesstra et al., 2018). unfortunately, tropical watersheds are increasingly threatened by a range of factors, including deforestation, land use change, and climate change (brooks et al., 2019; lees et al., 2020; naeem et al., 2015). deforestation and land use change can lead to soil erosion, sedimentation, and altered hydrological regimes, while climate change can exacerbate the impacts of these threats and lead to changes in precipitation patterns and increased water stress (gupta et al., 2019; poff et al., 2016; shrestha et al., 2019). furthermore, tropical watersheds face significant water-related challenges, such as water scarcity, water pollution, and water-borne diseases (hodges et al., 2020; world health organization, 2019). these challenges can have severe impacts on human health, particularly in low-income communities chandrathilake /journal of tropical forestry and environment vol. 12, no. 02 (2022) 1-9 2 that rely on natural resources for their livelihoods (hodges et al., 2020; world health organization, 2019). therefore, it is imperative to understand the factors that affect water quality and quantity in tropical watersheds to develop effective management strategies and ensure the sustainability of water resources. ecohydrology is an interdisciplinary field that aims to understand the interactions between ecological and hydrological processes and their feedbacks, with the goal of informing sustainable management of water resources (scanlon et al., 2013; sivapalan et al., 2019). the term 'ecohydrology' was first coined in the early 2000s, although the concept of studying the interplay between ecosystems and water has a long history dating back to the 19th century (blöschl et al., 2019; zalewski, 2000). however, it wasn't until the late 20th century that the term gained popularity and emerged as a distinct field of study (bonell and bruijnzeel, 2004; savenije, 2004). thus, ecohydrology is an emerging field that can help address these challenges by studying the interactions between water, vegetation, and soil (chandrathilake, 2019; jenerette et al., 2016; sivapalan et al., 2012). ecohydrology has theoretical and practical significance in addressing current water management challenges. it offers a holistic approach to water management by considering the biotic and abiotic components of an ecosystem and their interactions with the water cycle. ecohydrological principles have been applied to improve water management practices in various settings, including natural and agricultural ecosystems, urban areas, and river basin management. for instance, ecohydrology has been used to develop water management strategies that consider both the quantity and quality of water required for various ecosystem services (gibert et al., 2010). it has also been used to promote sustainable land use practices and reduce the negative impacts of human activities on water resources (jiang et al., 2019). compared to traditional hydrology approaches, ecohydrology provides a more comprehensive understanding of water systems and their interactions with ecosystems, which can improve the effectiveness of water management practices (sivapalan et al., 2012). ecohydrology is particularly relevant to tropical forests, as these ecosystems are characterized by high biodiversity and complex hydrological processes (köhler et al., 2019; loescher et al., 2018). ecohydrological research can help identify the critical functions and driving forces that regulate water quality and quantity in tropical watersheds, as well as the role of forests in providing water-based ecosystem services (mcdonnell et al., 2020; scott et al., 2019). by combining interdisciplinary approaches and long-term monitoring, ecohydrology can provide valuable insights for the sustainable management of tropical watersheds and the conservation of tropical forests. ecohydrology is a rapidly evolving field that spans the disciplines of ecology, hydrology, and biogeochemistry. as a result, there are now several journals dedicated to publishing research related to ecohydrology. these journals include ecohydrology, hydrology and earth system sciences, ecohydrology and hydrobiology, journal of hydrology, and water resources research, among others. the existence of these dedicated journals underscores the growing recognition of the importance of ecohydrology in understanding the complex interactions between water and ecosystems. furthermore, it highlights the need for interdisciplinary research to address critical issues related to water availability, water quality, and the sustainability of aquatic and terrestrial ecosystems. guswa et al. (2020) emphasizes the importance of interdisciplinary collaboration and diverse methodologies in ecohydrology research to address the complex challenges facing freshwater systems. jun et al. (2021) provided a comprehensive review of the progress, challenges, and future directions of ecohydrology research in china, highlighting the need for a more holistic approach to water resources management, including the incorporation of socio-economic and ecological factors. together, these studies underscore the critical role of ecohydrology in addressing the urgent challenges of freshwater resource management and the need for interdisciplinary collaboration in research. chandrathilake /journal of tropical forestry and environment vol. 12, no. 02 (2022) 1-9 3 ecohydrology is an emerging field of study that seeks to understand the complex interactions between hydrological processes and biotic factors in natural ecosystems. it provides a framework for understanding the role of vegetation, soil, and water in regulating water quantity and quality, and how these processes can be influenced by human activities (sivapalan et al., 2019). ecohydrological research has shown that tropical forests play a critical role in regulating water flows and water quality, and that changes in land use and climate can have profound impacts on these processes (bruijnzeel et al., 2011; jauch et al., 2020). wright et al. (2017) conducted a comprehensive review of ecohydrology, highlighting the importance of interdisciplinary collaboration and the need for a more nuanced understanding of the feedback mechanisms between ecological and hydrological processes. they emphasized the role of ecohydrology in addressing critical challenges such as water scarcity and ecosystem degradation, and stressed the need for a more holistic approach to water resources management that incorporates both human and ecological needs. in this article, we highlight the importance of healthy watersheds and the crucial role of tropical forests in providing clean water for human and ecosystem health. we also provide an overview of the emerging field of ecohydrology and its relevance to tropical forest ecosystems. specifically, we discuss the need for more ecohydrological research in tropical forests to better understand the complex interactions between hydrology and biota, and to inform sustainable land use and water management strategies. we highlight the importance of interdisciplinary collaboration and long-term monitoring for effective ecohydrological research, and provide examples of successful ecohydrological research projects in tropical forests. overall, this article emphasizes the urgent need for increased investment in ecohydrological research to ensure the long-term sustainability of tropical forest ecosystems and the watersheds they support. 2. methodology to write this feature article, we conducted a comprehensive literature review using various academic databases, including web of science, scopus, and google scholar. we used a combination of keywords such as "tropical forests," "watersheds," "eco-hydrology," "water regulation," "land use change," "climate change," and "water quality" to search for relevant articles published in peer-reviewed journals, reports, and books. focus was given on articles that discussed the importance of tropical forests in providing ecosystem services, including water regulation, and the threats facing tropical watersheds. at the same time articles that discussed the concept of ecohydrology and its relevance to tropical forest ecosystems were also considered. after careful selection, we reviewed articles that provided insights into the complex interactions between hydrological processes and biotic factors in tropical watersheds, and the role of ecohydrological research in informing sustainable land use and water management strategies. after reviewing and analyzing the literature, we synthesized the findings and identified the main themes and key points to be addressed in the article. we then developed an outline and drafted the article, using the introduction, methodology, results, discussion, and conclusion format. 3. results and discussions through our literature review, we have identified several key findings from ecohydrological research in tropical forests that shed light on the complex interactions between hydrological processes and biotic factors. this section will summarize the main results and provide an in-depth discussion of the implications of these findings for the sustainable management of water resources in tropical watersheds. chandrathilake /journal of tropical forestry and environment vol. 12, no. 02 (2022) 1-9 4 we will focus on the effects of deforestation, land use change, and climate change on water quality and quantity, as well as the role of forests in providing water-based ecosystem services. we will also discuss the importance of interdisciplinary collaboration and long-term monitoring for effective ecohydrological research and provide examples of successful ecohydrological research projects in tropical forests. 3.1 the challenges facing tropical forests and watersheds. tropical forests and watersheds face numerous threats that are adversely affecting their ecological health and water provisioning services. deforestation, land use change, and climate change are among the main challenges that these ecosystems are facing (bruijnzeel et al., 2011; lees et al., 2020; ochoagaona et al., 2014; pielke et al., 2011). deforestation and land use change can alter the water cycle by reducing infiltration, increasing runoff and soil erosion, and changing the amount and timing of streamflow (bruijnzeel et al., 2011; ranaivoson et al., 2020). these changes can lead to reduced water availability and quality, affecting both human populations and biodiversity (bruijnzeel et al., 2011; ranaivoson et al., 2020). climate change is also affecting the hydrological cycle and exacerbating the effects of land use change, leading to more frequent and severe droughts, floods, and landslides (davidson et al., 2012; ipcc, 2018). the loss of forest cover and the degradation of ecosystems are accelerating these impacts and threatening the resilience of these systems (bruijnzeel et al., 2011; lees et al., 2020). it is therefore essential to address these threats and promote the conservation and restoration of tropical forests and watersheds to maintain their ecological health and water provisioning services. these threats to tropical forests and watersheds have important implications for water availability and quality, which are critical for human and ecosystem health. reduced water availability can lead to increased competition for water resources and conflicts among water users, while degraded water quality can pose risks to human health and aquatic ecosystems (vörösmarty et al., 2010; walsh et al., 2017). furthermore, water scarcity and pollution can have negative impacts on economic development and food security (falkenmark et al., 2007; schreier et al., 2018). it is therefore essential to address these threats and protect the health and functioning of tropical watersheds for the benefit of present and future generations. 3.2 the role of ecohydrological research in tropical forests ecohydrological research in tropical forests aims to address key questions related to the functioning of forested watersheds and their response to environmental change. these questions include understanding the hydrological processes that govern water availability and quality in tropical forests (bruijnzeel et al., 2011), the role of vegetation and soil moisture in regulating water fluxes (jackson et al., 2019), and the potential impacts of land use change and climate change on water resources (huang et al., 2021). ecohydrology also seeks to identify critical ecosystem services provided by tropical forests, such as carbon sequestration and biodiversity conservation, and to quantify the trade-offs between these services and water resources (mcdonnell et al., 2020). ultimately, the objective of ecohydrological research in tropical forests is to inform management strategies for healthy watersheds and sustainable use of water resources (silvestri et al., 2013). ecohydrological research provides critical information for developing effective land use planning and management strategies to maintain healthy watersheds in tropical forests. by understanding the hydrological processes and biotic dynamics within watersheds, ecohydrology can provide insights into the impacts of land use changes on water quantity and quality, and identify ways to mitigate negative effects on ecosystems and human communities (van dijk and keenan, 2015). for example, ecohydrological research has been used to evaluate the effectiveness of riparian buffer zones in mitigating sediment and nutrient pollution in waterways (merritt et al., 2010). ecohydrological models can also be used to predict the impacts of land use changes on water availability and quality, and inform land use planning decisions (lees et al., 2020). by providing evidence -based information, chandrathilake /journal of tropical forestry and environment vol. 12, no. 02 (2022) 1-9 5 ecohydrological research can support the development of sustainable land use practices that balance conservation and human needs in tropical watersheds. additionally, ecohydrological research can inform the development of payment for ecosystem services (pes) schemes that incentivize conservation practices in tropical forests. these schemes compensate landowners for providing ecological services such as water regulation, carbon sequestration, and biodiversity conservation (wunder, 2019). ecohydrological research can provide the scientific basis for designing and implementing pes schemes that are effective in achievin g conservation goals while also benefiting local communities (lees et al., 2020). in this way, ecohydrological research can contribute to the development of sustainable economic models that promote both environmental and social well-being. there have been several successful ecohydrological research projects in tropical forests that have demonstrated the importance of this field in understanding and managing watersheds. one such project is the luquillo critical zone observatory in puerto rico, which has been studying the hydrological and biogeochemical processes in a tropical rainforest ecosystem for over 25 years (brantley et al., 2017). the research has identified the complex interactions between vegetation, soils, and water resources, and their role in regulating the hydrological cycle. another example is the amazon face project, which is investigating the effects of elevated carbon dioxide levels on the water cycle and ecosystem dynamics in the amazon rainforest (keller et al., 2020). the research aims to improve our understanding of how tropical forests will respond to future climate change and inform management strategies for maintaining healthy watersheds. these and other successful ecohydrological research projects demonstrate the importance of interdisciplinary collaboration and long-term monitoring for understanding the complex dynamics of tropical watersheds and developing effective management strategies. 3.3 the need for more ecohydrological research in tropical forests despite the critical importance of tropical forests in providing clean water and maintaining healthy watersheds, there are still significant gaps in our understanding of the ecohydrological processes that underlie these services. guswa et al. (2020) argues that current knowledge gaps in ecohydrology research are particularly acute in tropical regions, where the complex interplay of hydrology and biota can vary significantly across different forest types and climates. to effectively manage and protect these valuable ecosystems, it is essential that we invest in more interdisciplinary ecohydrological research that focuses on understanding the fundamental mechanisms that regulate water quality and quantity in tropical watersheds. long-term monitoring and interdisciplinary collaboration are also crucial for advancing ecohydrological research in tropical forests. this is because ecohydrology requires the integration of various disciplines such as hydrology, ecology, biogeochemistry, and geomorphology, which often require long-term data collection and analysis (mcdonnell et al., 2015). the development of new technologies such as remote sensing, modeling, and data visualization tools can aid in this effort and help to build a more comprehensive understanding of the complex interactions between hydrology and biota in tropical forests (turner and sabine, 2019). furthermore, recent research has emphasized the importance of incorporating indigenous knowledge and perspectives into ecohydrological research and management practices in tropical watersheds (ackerly et al., 2021). by valuing and integrating diverse forms of knowledge and experience, ecohydrology can help to support more equitable and sustainable approaches to watershed management. investing in ecohydrological research in tropical forests can provide numerous benefits for both conservation and watershed management efforts. by identifying critical ecohydrological functions and driving forces that regulate the quality and quantity of water, this research can inform the development of land use planning and management strategies that balance human needs with ecological sustainability. chandrathilake /journal of tropical forestry and environment vol. 12, no. 02 (2022) 1-9 6 furthermore, understanding the hydrological processes in tropical watersheds can help to predict and mitigate the impacts of climate change and land use change on water resources (bruijnzeel, 2004; turner and sabine, 2019). ultimately, investing in ecohydrological research can help to ensure the long-term sustainability of tropical forests and the vital ecosystem services they provide (ackerly et al., 2021). 4. conclusion in conclusion, tropical forests play a vital role in providing clean water for human consumption and ecosystem health, but are facing significant threats such as deforestation, land use change, and climate change. ecohydrological research offers a promising approach to better understand the complex relationships between tropical forests, watersheds, and water resources. by providing insights into the hydrological processes that underpin healthy watersheds, ecohydrological research can inform land use planning and management strategies that promote sustainable watershed management. however, there are still many gaps in our knowledge and research on ecohydrology in tropical forests, which underscores the need for interdisciplinary collaboration and long-term monitoring efforts. investing in ecohydrological research can not only benefit tropical forest conservation and watershed management but also promote more sustainable use of natural resources in the face of global environmental change. references ackerly, d.d.a.r., davis, k.a., dudley, k.j., isaac, e. j., kelly, k. j., loik, h.a., mooney, j.a. wiens. and westoby m. 2021. innovations in ecology: a call for innovation in ecohydrology. frontiers in ecology and the environment, 19: 191– 98. ackerly, d.d., dudley, s.a., harrison, s.p. and lebauer, d.s. 2021. advancing ecology through synthesis. nature ecology and evolution, 5(5): 607-608. blöschl, g., sivapalan, m., wagener, t., viglione, a. and savenije, h. 2019. runoff prediction in ungauged basins: synthesis across processes, places and scales. cambridge university press. bonell, m. and bruijnzeel, l.a. 2004. forests, water and people in the humid tropics: past, present and future hydrological research for integrated land and water management. cambridge university press. brantley, s.l. 2017. designing a network of critical zone observatories to explore the living skin of the terrestrial earth. earth surface dynamics, 5(4): 841-860. brooks, t.m., mittermeier, r.a., da fonseca, g.a., gerlach, j., hoffmann, m., lamoreux, j. f. and pilgrim, j.d. 2019. global biodiversity conservation priorities. science, 313(5783): 58-61. bruijnzeel, l.a. 2004. hydrological functions of tropical forests: not seeing the soil for the trees? agriculture, ecosystems and environment, 104(1): 185-228. bruijnzeel, l.a., hamilton, l.s. and galloway, j. n. 2011.tropical forests and climate change: maintaining resilience and increasing adaptation. iufro world series, 22. bruijnzeel, l.a., hamilton, l.s. and galloway, j.n. 2011. tropical forests and global atmospheric change: a synthesis. cambridge university press. bruijnzeel, l.a., kappelle, m., mulligan, m. and scatena, f.n., 2010. tropical montane cloud forests: state of knowledge and sustainability perspectives in a changing world. cerda, a., keesstra, s. d., cerdà, a. and keesstra, s. 2018. the effects of soil management practices on soil erosion: a mediterranean case study. land degradation and development, 29(6): 18261834. chandrathilake, g.g.t. 2019. ecohydrology a blue-green paradigm for water resources management. proceedings of the 75th annual sessions – 2019, sri lanka association for the advancement of science. chazdon, r.l., brancalion, p.h., laestadius, l., bennett-curry, a., buckingham, k., kumar, c., mollrocek, j., vieira, i.c.g. and wilson, s.j., 2016. when is a forest a forest? forest concepts and definitions in the era of forest and landscape restoration. ambio, 45(5): 538-550. davidson, n.c., dugan, p.j., finlayson, c.m. and milton, g.r. (eds.). 2012. the wetland book: i: structure and function, management, and methos. springer science and business media. chandrathilake /journal of tropical forestry and environment vol. 12, no. 02 (2022) 1-9 7 ewers, r.m., boyle, m.j., gleave, r.a., plowman, n.s., benedick, s., bernard, h. and edwards, d. p. 2015. logging cuts the functional importance of invertebrates in tropical rainforest. nature communications, 6(1): 1-8. falkenmark, m., rockstrom, j. and lannerstad, m. 2007. policies and measures to address the global water crisis. water policy, 9(s1): 131-144. gibbs, h.k., ruesch, a.s., achard, f., clayton, m.k., holmgren, p., ramankutty, n. and foley, j.a. 2010. tropical forests were the primary sources of new agricultural land in the 1980s and 1990s. proceedings of the national academy of sciences, 107(38):16732-16737. gibert, k., lasseur, j., louchart, x., michon, g. and larnier, k. 2010. integrating ecohydrology into water resources management: a review. journal of hydrology, 389(3-4): 377-388. gupta, m., varghese, j., goyal, m. k. and kumar, a. 2019. ecohydrology: a review. journal of the geological society of india, 93(6): 631-645. guswa, a.j., tetzlaff, d., selker, j.s., carlyle‐moses, d.e., boyer, e.w., bruen, m., cayuela, c., creed, i.f., van de giesen, n., grasso, d. and hannah, d.m. 2020. advancing ecohydrology in the 21st century: a convergence of opportunities. ecohydrology, 13(4): p.e2208. hodges, c., stork, n. e. and kessner-beierlein, d. 2020. the global distribution of insect declines: systematic review and meta-analysis. peerj, 8: e9879. huang, c., yan, j., wang, y., zheng, h. and liu, c. 2021. hydrological response to climate change in a small watershed in the tropical mountainous area of southern china. hydrology research, 52(2): 238-253. intergovernmental panel on climate change, 2018. global warming of 1.5° c: an ipcc special report on the impacts of global warming of 1.5° c above pre-industrial levels and related global greenhouse gas emission pathways, in the context of strengthening the global response to the threat of climate change, sustainable development, and efforts to eradicate poverty . intergovernmental panel on climate change. jackson, r.b., jobbágy, e.g. and nosetto, m.d. 2019. ecohydrology: past, present, and future. ecohydrology, 12(1): e2069. jauch, d., dzomeku, b.m. and bugmann, h. 2020. forest loss and water availability in tropical forests under a changing climate. global change biology, 26(9): 5102-5116. jenerette, g.d., scott, r.l. and huxman, t. e 2016. ecohydrology in drylands: an interdisciplinary approach to link soil water dynamics and vegetation dynamics at multiple scales. ecohydrology, 9(5): 717-728. jiang, x., wan, l., wang, j., xu, m. and gao, j. 2019. the role of ecohydrology in mitigating the negative impact of human activities on water resources. ecohydrology, 12(2): e2061. keesstra, s.d., mol, g., de leeuw, j., okx, j. and molenaar, w. 2018. soil-related sustainable development goals: four concepts to make land degradation neutrality and rest oration work. land degradation and development, 29(12): 3753-3763. keller, m. 2020. the amazon forest carbon and water cycles under changing climate: the roles of ecohydrology and atmospheric feedbacks. frontiers in forests and global change, 3: 24. köhler, l., tobón, c., rasmussen, k., ochoa-gutiérrez, m. and buytaert, w. 2019. a framework for understanding and diagnosing river basin hydrological complexity. journal of hydrology, 575: 1212-1224. lees, a.c., acri, d. j., bell, t., boucher, t., calosi, p., cerrato, c. and vianna, j.a. 2020. the scientific case for a rapid reduction in carbon emissions. bioscience, 70(12): 1200-1203. lees, a.c., peres, c.a., fearnside, p.m., schneider, m., zuanon, j. a.s. and machado, r.b. 2020. hydropower and the future of amazonian aquatic biodiversity. biodiversity and conservation, 29(4): 1105-1124. loescher, h.w., kominoski, j.s., troxler, t g., gaiser, e.e. and childers, d.l. 2018. hydrological connectivity regulates nutrient transport, metabolism, and aquatic food webs. ecology, 99(9): 1952-1963. chandrathilake /journal of tropical forestry and environment vol. 12, no. 02 (2022) 1-9 8 mcdonnell, j.j., mcguire, k.j., aggarwal, p., beven, k., biondi, d., destouni, g. and tetzlaff, d. 2020. how old is streamwater? open questions in catchment transit time conceptualization, modelling and analysis. hydrological processes, 34(2): 412-421. mcdonnell, j.j., s.t. allen, s.s. azcona, d.l. buttle, c.l. kendall, d.k. levia, j.j. seibert , and shanley j. 2015. the future of hydrology: an evolving science for a changing world. water resources research, 51: 5929– 48. merritt, d.m., scott, m.l., leroy, c.j., auble, g.t., and lytle, d.a. (2010). riparian vegetation and the regulation of water quality along the freshwater-to-estuarine continuum. journal of the american water resources association, 46(2), 211-226. naeem, s., chazdon, r., duffy, j e., prager, c., worm, b. and watson, j.e. 2015. biodiversity and human well-being: an essential link for sustainable development. proceedings of the royal society b: biological sciences, 282(1815):2014-2454. ochoa-gaona, s., del amo, r.l. and mas, j.f. 2014. land use/land cover change and ecosystem services provisions in the tropical rainforest region of chiapas, mexico. forests, 5(5): 958-979. pielke sr, r.a., adegoke, j., beltraán-przekurat, a., hiemstra, c.a., lin, j., nair, u.s., niyogi, d. and nobis, t.e., 2007. an overview of regional land-use and land-cover impacts on rainfall. tellus b: chemical and physical meteorology, 59(3): 587-601. poff, n.l., brown, c.m., grantham, t.e., matthews, j.h., palmer, m.a., spence, c.m. and wilby, r. l. 2016. sustainable water management under future uncertainty with eco-engineering decision scaling. nature climate change, 6(1): 25-34. ranaivoson, c., raparison, h.n., rakotondraompiana, s.r., andrianarisoa, s.h. and razakamanarivo, h.r. 2020. effects of land use change on soil erosion and water quality in a small mountainous watershed in madagascar. applied water science, 10(3): 64. savenije, h.h. 2004. ecohydrology: a new interdisciplinary research agenda. hydrological processes: an international journal, 18(20): 3437-3440. scanlon, b.r., ruddell, b.l., reed, p.m., hook, r.i., zheng, c., tague, c. and harmon, t.c. 2013. the food-energy-water nexus: transforming science for society. water resources research, 49(9): 5319-5333. schreier, h., adams, j. e., nguyen, t. h. and annamalai, k. 2018. water quality and food production: poor water quality reduces food production in rural areas. water international, 43(7): 918-935. scott, d.f., loescher, h.w. and le maitre, d.c. 2019. hydrology and ecohydrology of south africa's indigenous forests and woodlands: a review. south african journal of botany, 125: 88-101. shrestha, r.k., ahmed, b., shakya, n. m. and nepal, r. m. 2019. eco-hydrological assessment of groundwater recharge in kathmandu valley, nepal. hydrology research, 50(4): 1128-1144. doi: 10.2166/nh.2019.084 silvestri, s., bryan, r.b., ringler, c., herrero, m., okoba, b. and willcock, s. 2013. climate change, water governance and the practicalities of hydrological model calibration in africa. hydrology and earth system sciences, 17(5): 1865-1879. sivapalan, m., savenije, h.h. and blöschl, g. 2012. socio-hydrology: a new science of people and water. hydrol. process, 26(8): 1270-1276. turner, b.l. and sabine, c.l. 2019. global environmental change: the ultimate challenge to interdisciplinary research. environmental science and policy, 101: 1-6. turner, b.l. and s. sabine. 2019. remote sensing and tropical ecosystems: a state-of-the-art review. remote sensing, 11: 19. van dijk, a.i. j. m. and keenan, r.j. 2015. placing ecohydrology at the nexus of climate, food, water and energy. ecohydrology, 8(4):679-680. vörösmarty, c.j., mcintyre, p.b., gessner, m.o., dudgeon, d., prusevich, a., green, p. and davies, p. m. 2010. global threats to human water security and river biodiversity. nature, 467(7315): 555-561. walsh, c.j., roy, a.h., feminella, j.w., cottingham, p.d., groffman, p.m. and morgan ii, r.p. 2017. the urban stream syndrome: current knowledge and the search for a cure. journal of the north american benthological society, 29(1): 168-181. chandrathilake /journal of tropical forestry and environment vol. 12, no. 02 (2022) 1-9 9 world health organization, 2019. microplastics in drinking-water. wunder, s. 2019. forests, water and payments for ecosystem services: an overview with lessons for africa. ecosystem services for well-being in deltas, 117-136. xia, j., zhang, y., mu, x., zuo, q., zhou, y. and zhao, g. 2021. a review of the ecohydrology discipline: progress, challenges, and future directions in china. journal of geographical sciences, 31(6): 985-1002. zalewski, m. 2000. ecohydrology—the scientific background to use ecosystem properties as management tools toward sustainability of water resources. ecological engineering, 16(1): 18. 54 decomposition and nitrogen release patterns of parkia biglobosa and albizia lebbeck leaves with nitrogen fertilizer for maize production in sudan savanna alfisol of nigeria *n. a. oyebamiji1, a. o. babalola2 and a. m. aduradola3 *1department of forestry and wildlife management, federal university dutsin-ma, nigeria 2department of soil science and land management, federal university of agriculture, abeokuta, nigeria. 3department of forestry and wildlife management, federal university of agriculture, abeokuta, nigeria. date received: 24-01-2017 date accepted: 20-03-2017 abstract biomass transfer or cultivation of leguminous trees has higher eco-friendly profiles for soil nutrients restoration especially nitrogen. the research is conducted on decomposition and nitrogen release patterns of parkia biglobosa and albizia lebbeck leaves with nitrogen fertilizer for maize production in sudan savannah alfisol of nigeria. data were analysed using (anova). 56 % of n in the litter bag was released the first two weeks of biomass incubation and progressively increases weeks after planting. decomposition rate constant (kd) ranged from 9.18 to 15.07 week-1 and the rates of plant residues was higher in albizia lebbeck than parkia biglobosa in both seasons. nitrogen release rate constant (kn), ranging from 7.82 to 10.81 week-1 followed a similar pattern as the rate of decomposition with albizia lebbeck releasing the highest amount of n followed by parkia lebbeck. the rate of decomposition increased as week increased. incorporation of albizia lebbeck had significantly higher effect (p < 0.05) on growth parameter and yield component compared to parkia biglobosa. the study concluded that albizia lebbeck decomposed and mineralized faster for crop uptake under sudan savanna conditions. the study suggests that incorporation of albizia lebbeck and up to 40 kg n ha-1 is a better combination for soil quality improvement and maize productivity in makera, a semi-arid environment of nigeria. keywords: agroforestry trees, decomposition, leafy biomass, nitrogen release, fertilizer, maize production 1. introduction lack of soil fertility restoring resources, soil erosion and unequal soil fertility management have been reported to contribute to soil fertility depletion in arid africa (bationo et al., 2007; vanlauwe and giller, 2006). leguminous trees that are nitrogen fixing trees are known to play complementary or alternative role as source of organic fertilizer and have the potential to sustain soil fertility (giller, 2001; snapp et al., 2003; adjei-nsiah et al., 2004). understanding decomposition and nutrient release or nitrogen mineralisation patterns of plant materials is an important first step to better managing organic inputs that are applied in agroforestry and other related land-use systems (palm, 1995; mafongoya et al., 1998). these in turn depend to a large extent on chemical composition of plant tissues (constantinides and fownes, 1994). initial n content of the biomass, c: n ratio, lignin content, lignin: n ratio, and polyphenol and its ratios with n and lignin have been shown to be important chemical qualities affecting the rate of decomposition and mineralization (palm, 1995; mafongoya et al., 1998). other factors that affect the rate of mineralization include climate, soil characteristics, and cultural practices such as the method of *correspondence: noyebamiji@fudutsinma.edu.ng issn 2235-9370 print / issn 2235-9362 online ©2017 university of sri jayewardenepura oyebamiji et al. /journal of tropical forestry and environment vol. 07, no. 01 (2017) 54-64 55 application of biomass, application of mineral fertilizers, and methods employed in soil tillage (becker et al., 1994b; mugendi and nair, 1997). residue decomposition rates and nutrient release or mineralisation patterns are controlled by both biotic and abiotic factors, the most important of which is residue quality (vanlauwe et al., 1996; silver and miya, 2001; mungai and motavalli, 2006; teklay et al., 2007). in order to manage the n mineralised from organic residues for crop uptake, there is need to understand decomposition and n mineralization patterns of the organic inputs in relation to their chemical composition. it has been established by various researchers that high lignin and polyphenol contents as well as high c: n ratios in leaves tend to slow down litter decomposition and nutrient release (upadhyaya et al., 2012; constantinides and fawnes, 1994; handayanto et al., 1994). multipurpose trees (mpts) which are low in polyphenols, can provide a rapid flush of n during mineralisation, and may therefore be a good choice for use with annual crops such as maize which requires large amounts of n in a short period of time. nitrogen release by plant litter or biomass with high contents of polyphenols, lignin and c: n ratio is slow so that decomposition occurs over a long period of time (palm, 1988). inorganic fertilizers have gained popularity because, they are easy to manage, handle and apply. this is because it is easier to synchronize the release of nutrients and plant uptake with inorganic fertilizers than with manure (mclaughlin et al., 2002). chemical or mineral fertilizers have been reported to increase cereal rooting depth and root proliferation (belford et al., 1987; brown, 1987). however, few smallholder farmers can afford mineral fertilizers, and those using fertilizer hardly use the recommended rates (mugwe et al., 2009). moreover, the little fertilizer available when added to the soil is often utilised with poor efficiency (vanlauwe et al., 2010) due to environmental or soil-related factors (e.g leaching and volatilization of n) as well as management factors (e.g. poor timing or placement of fertilizer). on the other hand, the use of locally available manure is also limited by its low quality and quantity (bationo and waswa, 2011; murwira et al., 2002; sanginga and woomer, 2009). 1. methodology study area the study area was makera, a village in dutsin-ma local government area of katsina state. dutsin-ma has an area of 527 km², altitude of 605 m, population of 169, 671 and lies within latitude 12027'18" n and longitude 07029'29"e and also found in the basement complex derived soils of katsina state (oguntoyinbo, 1993). the inhabitants of the area are farmers and they are predominantly hausa and fulani by tribe. their main occupation is farming and animal rearing. experimental design this study was carried out at makera, beside the nursery unit of the federal university dutsinma, katsina state, nigeria from 2014 and 2015 cropping seasons. soil sample was collected from the fallow site of the farm. physical and chemical properties of the soil were determined prior to the commencement of the experiment using standard methods. the experiments were laid in split-split plot design in 3 x 4 x 2 factorials with three replicates. the plot dimensions were 4 m x 3 m. leafy biomass of albizia lebbeck and parkia biglobosa were pruned and incorporated fresh into the soil at the rate of 6 kg for each (5000 kg ha-1) of the albizia lebbeck and parkia biglobosa biomass plots (b1 and b2) respectively and plots without incorporation of leafy biomass (b0). the leafy biomass was incorporated into the soil for two cropping seasons (2014 and 2015). four levels of n fertilizers were split applied as: n0, 0 kg n ha -1 (control); n1, 40 kg n ha -1; n2, 80 kg n ha -1; n3, 120 kg n ha -1 and half were applied at 2 weeks after planting (wap). the remaining amount was applied 5 (wap). the two varieties of maize used were (dmresr7 (yellow maize) and 2009 evat (white maize) were obtained from katsina state agricultural and rural development authority (ktarda). two maize varieties were planted (two maize seeds were planted per hole, at equal depth and it was later 56 thinned to one) by conventional spacing of 75 cm x 25 cm two weeks after incorporation of leafy biomass of albizia lebbeck and parkia biglobosa into the soil. thinning was also done 2 (wap) making the total plant population of 64 stands per plot. plant tissue analysis of agroforestry tree species harvested leaves samples were air dried at the room temperature and ground to be analysed for initial contents of n, lignin and polyphenols. total n was analysed by macro-kjeldahl digestion, followed by distillation and titration (anderson and ingram, 1993; brandstreet, 1965). lignin and cellulose were determined by the acid detergent fibre (adf) method as outlined in (anderson and ingram, 1993). the polyphenols was extracted in hot (800 c) 50 % aqueous methanol and determined calorimetrically with tannic acid as a standard measurement (anderson and ingram, 1993; hagerman, 1988). decomposition patterns fifty (50) grams of the tree-leafy biomass from all the treatments that received biomass application was placed in 1-mm mesh size litter bags and buried into the soil at a depth of about 15 cm at the time of maize planting (beginning of the season). one bag containing residues from each species were randomly removed from the soil in each plot at 2, 4, 6, 8 and 10 weeks after maize planting (wap). the contents in the bags were cleaned with water, oven dried at 650 c to constant weight, and dry weights were recorded. y = e–kt, where y is the percent remaining of initial weight of material at time t in weeks and k is the rate of decomposition/n release per week (rate constant). the k values were estimated using a nonlinear module in sas (2000). nitrogen released (rls) over time were calculated following the formula by giashuddin et al. (1993). % n rls = 100 – % of original n content remaining (n0) where, no = (% n a time t) x % of original weight remaining (% n at time 0) statistical analysis data were subjected to analysis of variance (anova) using statistical analysis system (sas, 2000) computer package at 5 % level of significance to determine differences in the treatment effect. the duncan’s multiple range test (duncan, 1955) was used to separate means of differences among the treatments. 2. results some properties of the soil before planting soil physical and chemical properties were collected at the experimental site before the commencement of the experiment is presented in table 1. the soil is low in total nitrogen and organic carbon with (0.04 % and 0.53 %) respectively. the soil distribution of exchangeable basic cations fallows this order: ca>mg>na>k. nitrate-nitrogen was higher than ammonia-nitrogen in the soil. the ph of the soil is acidic. the soil belongs to the textural class sandy loam. oyebamiji et al. /journal of tropical forestry and environment vol. 07, no. 01 (2017) 54-64 57 table 1: soil physical-chemical properties before establishment of the experiment at makera. 2014. soil properties value particle size (g/kg) sand 88.6 silt 4 clay 7.4 textural class sandy loam chemical properties ph 4.1 organic carbon (%) 0.53 total nitrogen (%) 0.04 nh4 +n (mgkg-1) 23.99 no3 -n(mgkg-1) 26.38 available phosphorus (mg kg-1) 7.94 exchangeable bases (c mol kg-1) ca 6.25 mg 1.01 k 0.2 na 0.35 al+h 0.15 cec 7.96 chemical composition of leafy biomass of the albizia lebbeck and parkia biglobosa the plant materials showed slight variations between albizia lebbeck and parkia biglobosa in their chemical compositions during 2014 and 2015 cropping seasons. the leaves of albizia lebbeck contained more n (leading to lower c: n ratio) than parkia biglobosa. albizia lebbeck had the highest concentration of lignin with mean value of 11.06, while parkia biglobosa had highest concentration of c: n ratios with mean value of 6.30. the result in (table 2) showed that parkia biglobosa had low n and c contents compared with albizia lebbeck. table 2: initial chemical composition of the biomass of albizia and parkia plant species component n % c % lignin % polyphenol % c: n albizia lebbeck 2014 3.32a 18.62a 11.37a 0.65b 5.60b 2015 3.16a 18.65a 10.74a 0.48b 5.90b means 3.24a 18.64a 11.06a 0.57b 5.75b parkia biglobosa 2014 2.85b 17.81b 8.35b 0.87a 6.20a 2015 2.44b 15.52b 8.13b 0.63a 6.40a means 2.65b 16.67b 8.24b 0.75a 6.30a n= nitrogen; c= carbon; c:n= carbon/n ratio means followed by the same letter(s) within the same column and treatment are not significantly different at 5 % level of probability using dmrt. decomposition patterns of plant residues 50 g fresh weight of biomass was put inside litter bags for their decomposition. in general, there was a rapid loss of mass from the litter bags during the first two weeks after planting (2 wap) for the two species (figure 1) in this order albizia lebbeck (38.2 g) < parkia biglobosa (28.16 g) compared to initial weight of 50 g. at the end of four weeks after planting (4 wap), albizia lebbeck 58 had lost 42.19 g of its initial weight while 30.04 g of parkia biglobosa had been decomposed. at 6 wap, the rate of mass loss due to decomposition declined in both species. even then, albizia lebbeck continued to decompose faster compared with parkia biglobosa. the rate of decomposition increased thereafter. figure 1: loss weight of albizia and parkia leafy biomass over a period of 10 weeks decomposition rates and n release patterns the decomposition rate (kd) and n release rate (n) constants among albizia lebbeck and parkia biglobosa leafy biomass were considered significantly different from each other during the two seasons (table 3). albizia lebbeck biomass had the highest kd and kn rate constants, meaning that, it had the most rapid decomposition and n release rates followed by parkia biglobosa. table 3: decomposition rate (kd) and n release (kn) constants and their coefficient of determination (r2) values for the different residues in the semi-arid of nigeria means followed by the same letter within a column in a particular season are not significantly different at 5 % level of probability. kd and kn values are k/week. dry matter yield consistently plots amended with albizia lebbeck had significantly higher values of dry matter yield than other treatments at all sampling periods in 2014 and 2015. in 2014, the control treatment produced significantly lower values (15.1 kg ha-1, 49 kg ha-1, 66.9 kg n ha-1, 87 kg n ha-1) of dry matter than in plots supplied with nitrogen. among the nitrogen treated plots the values were mostly comparable but numerically higher with increase in n rate. in 2015, plots supplied with 120 kg n ha-1 had highly increasing values of dry matter at than other n treatments 6, 8 and 10 wap. there was no season plant residue kd r2 kn r2 2014 albizia 15.07a 0.98 10.81a 0.99 parkia 9.18b 0.98 7.92b 0.99 2015 albizia 15.00a 0.93 10.67a 0.98 parkia 10.69b 0.93 7.85b 0.98 oyebamiji et al. /journal of tropical forestry and environment vol. 07, no. 01 (2017) 54-64 59 significant difference among varieties in 2014, while at 8 and 10 wap, 2009 evat had significantly higher values ( 96.1 kg ha-1, 132.3 kg ha-1) of dry matter in 2015 (table 4). table 4: influence of biomass and nitrogen rate on dry matter yield per plant (g) of two maize varieties in 2014 and 2015 dry matter yield per plant 2014 2015 treatment 4 wap 6 wap 8 wap 10 wap 4 wap 6 wap 8 wap 10 wap biomass (b) control 13.9c 58.0b 88.3b 123.5b 7.0a 60.9b 87.4b 130.8a albizia 21.9a 81.3a 116.1a 157.8a 6.3a 83.4a 107.5a 127.0a parkia 18.7b 67.3ab 93.9b 136.5ab 5.8a 41.5c 65.9c 94.5b se± 1.09 6.42 8.48 12.63 0.57 4.95 6.96 8.79 nitrogen(n)kg ha-1 0 15.1c 49.0b 66.9b 87.0b 6.2a 57.6b 81.5b 101.2b 40 16.7bc 75.0a 109.5a 140.7a 6.5a 52.6b 73.8b 106.3b 80 18.7ab 68.7ab 106.9a 155.7a 6.8a 55.9b 78.5b 125.0ab 120 22.0a 82.8a 114.5a 173.7a 6.1a 81.5a 113.8a 137.2a se± 1.36 7.04 8.97 12.49 0.71 6.5 8.15 10.32 variety (v) dmr esr7 18.1a 68.0a 96.7a 145.2a 6.4a 57.2a 77.7b 102.6b 2009 evat 18.2a 69.8a 102.2a 133.3a 6.4a 66.6a 96.1a 132.3a se± 1.07 5.41 7.18 10.52 0.5 4.78 5.98 7.28 interaction b x n s* s* s* s* s* s* s* s* b x v s* s* ns s* ns s* s* s* v x n s* s* s* s* ns s* s* s* means followed by the same letter(s) within the same column and treatment are not significantly different at 5 % level of probability using dmrt. wap: weeks after planting. s* significant at 5 % level of probability. ns: not significant. grain yield plots amended with albizia lebbeck had significantly higher values (2097.2 kg ha-1, 1666.7 kg ha-1, 1881.9 kg ha-1) of grain yield than other treatments in all cropping seasons and their combined means. in 2014, and combined means, the control treatment produced significantly lower values (833.3 kg ha1, 912 kg ha-1) of grain yield than plots supplied with other n rates. no significant response to n rates on grain yield was observed in 2015. no significant difference was observed among varieties on grain yield in all cropping seasons and combined analysis (table 5). 60 table 5: influence of biomass and nitrogen rate on grain yield (kg ha-1) of two maize varieties in 2014, 2015 grain yield (kg ha-1) treatment 2014 2015 combined biomass (b) control 1388.9b 1395.8ab 1392.4b albizia 2097.2a 1666.7a 1881.9a parkia 1413.2b 930.6b 1171.9b se± 210.71 162.49 136.18 nitrogen (n) kg ha-1 0 833.3b 990.7a 912.0b 40 1875.0a 1250.0a 1562.5a 80 1652.8a 1509.3a 1581.0a 120 2171.3a 1574.1a 1872.7a se± 221.33 201.49 152.62 variety (v) dmresr-7 1569.4a 1245.4a 1407.4a 2009 evat 1696.8a 1416.7a 1556.7a se± 180.69 147.99 117.56 interaction b x n s* s* s* b x v s* s* s* v x n s* s* s* means followed by the same letter(s) within the same column and treatment are not significantly different at 5 % level of probability using dmrt. wap: weeks after planting. s* significant at 5 % level of probability. ns: not significant. 3. discussion the soil is low in total nitrogen and organic carbon. the soil distribution of exchangeable basic cations fallows this order: ca>mg>na>k. the ph of the soil is acidic. the soil belongs to the textural class sandy loam. parkia biglobosa had low and n and c contents which had average of 2.65 % n and 16.67 % c and high c: n ratio which had average of 6.30. soil is used to deplete soluble n and this hinders crops growth, structural development and resulted to low crop yield. this agrees with the report of (giller, 2001) who stated that plant residues with high c: n ratio greater than 30:1 are likely to decompose slowly with initial net immobilization of n. it is noted that poor performance observed in plots incorporated with parkia biglobosa was due to the low quality of the plant materials. performance in albizia lebbeck plots was observed better because of the better quality materials embedded in it. its materials contain higher average n content of 3.24 % n and 18.64 % c and lower average c: n ratio of 5.75 than parkia biglobosa materials. according to (giller and wilson, 1991) who stated that plant residues with a smaller c: n (< 30:1) is liable to decompose more rapidly with a net mineralization of n after incorporation into the soil. hence, n is rapidly released and made readily available for crops. consequently, the essence is to reduce if not complete withdrawal of inorganic n fertilizer for maize production; this is in agreement with (olujobi and oyun, 2013) who stated that supply of biomass from the leguminous tree and decomposing them with demand of the companion crop help in the release and uptake functions of limiting nutrients. oyebamiji et al. /journal of tropical forestry and environment vol. 07, no. 01 (2017) 54-64 61 nitrogen released from the two leguminous plants partly followed the same pattern as decomposition for the first two weeks. over 56 % of n in the litter bag was released during the first two weeks of incubation for the two biomass species. thereafter, the n content in the remaining undecomposed litter generally increased with time for the two biomass types. the n release rate constants observed in this study indicates that albizia lebbeck and parkia biglobosa soil-incorporated biomass released up to 56 % of n into the soil after two to four (2 4 wap) of incorporation and this also helped to boost the amount of mineral-n found in the soil in those treatments that received them. the differences in decomposition and n release between biomass of albizia lebbeck and parkia biglobosa tree species could be interpreted by the amount of initial n concentration and c: n ratios contained in the tissue of these plant materials. meanwhile, albizia lebbeck leafy biomass that had significantly higher n concentration and lower c: n ratio than parkia biglobosa decomposed and released n faster than parkia biglobosa over the entire 10 weeks study period which is in agreement with the results of others that n content and c: n ratio serve as relevant bases for decomposition and n release study (mugendi and nair, 1997). it is noted that parkia biglobosa contain high level of polyphenol which is known to have been confirmed and reported by other researcher to inhibit microbial activities, thereby slowing down the rate of decomposition and n release (chesson, 1997; mafongoya et al., 1998). lignin too also determines the rate of decomposition and its role in litter decay and nutrient release is widely reported in literature (jama and nair, 1996; mafongoya et al., 1998). lignin is known for its highly resistant to microbial decomposition and its slowing down of n mineralization due to binding of n (chesson, 1997). high lignin and polyphenol content in organic materials hamper the mineralization process due to their ability to bind proteins, thus determine the quality of organic materials to be decomposed by soil microbes (handayanto et al.,1997). therefore, it is important to note that decomposition and nutrient release are governed by the chemical composition of the plant materials. the general performance of maize plants was higher in albizia lebbeck amended plots, especially on total dry matter per plant and grain yield. yield increases as nitrogen are released from leguminous crops (peoples et al., 1995; mugendi et al., 2000; kang et al., 1999). incorporation of biomass often caused increased grain yield of maize than maize without incorporation of biomass (control). application of n from 40 kg n ha-1 to 120 kg n ha-1 had an increasing effect on grain yield. this finding agree with that of buah et al., (2009) who reported that 120 kg n ha-1 currently produced the highest grain yield of maize in the semi-arid, nigeria. patel et al., (2006) and el-gizawy, (2009) also supported the fact that increase in n application will always lead to increase in grain yield of maize. 4. conclusions the n rates released from decomposed biomass of both albizia lebbeck and parkia biglobosa was around 56 % nitrogen between two to four weeks of planting (2 4 wap). the differences in decomposition and nitrogen release patterns between albizia lebbeck and parkia biglobosa biomass was determined by the amount of initial n concentration and c: n ratios which are contained in the tissues of these plant materials. albizia lebbeck leafy biomass decomposed and released nitrogen faster and was significantly higher in n concentration and lower c: n ratio than parkia biglobosa. it was also noted that parkia biglobosa contained high level of polyphenol, hence, slowed down the rate of decomposition and n release. therefore, decomposition and nutrient release are governed by the chemical composition of the plant materials or residues. the use of biomass especially albizia lebbeck alone can also give increase in grain yield but when it is combined with nitrogen fertilizer, it will produce better and higher grain yield. therefore, incorporation of albizia lebbeck with 120 kg n ha-1 produced highest grain yield in 2009 evat. incorporation of albizia lebbeck and up to 40 kg n ha-1 is a better combination for soil quality improvement and maize productivity in makera, a semi-arid environment of nigeria. 62 acknowledgements i acknowledge the tetfund agency and federal university dutsin-ma for their support on this work. references adjei-nsiah, s., leeuwis, c., giller, k.e. 2004. “land tenure and differential soil fertility management practices among native and migrant farmers in wenchi, ghana: implications for interdisciplinary action research,” njas-wageningen, journal of life sciences. 52(3-4): 331–348. anderson j. m., ingram, j.s. 1993. tropical soil biology and fertility, a handbook of methods. cab international, wallingford. p 221. bationo, a., waswa, b., kihara, j., kimetu, j. 2007. advances in integrated soil fertility management in sub-saharan africa: challenges and opportunities. dordrecht, netherlands: springer. bationo, a.,waswa, b.s. 2011. new challenges and opportunities for integrated soil fertility management in africa. in innovation as key to the green revolution in africa. exploring the scientific facts, (eds a. bationo, b. waswa, j. m. okeyo, f. maina and j. kihara). new york, ny: springer. science +business media p. 1. becker, m., ladha, j.k., simpson, i.c., ottow, j.c.g. 1994. parameters affecting residue nitrogen mineralization in flooded soils. soil science society of america journal 58: 1666–1671. belford, r.k., klepper, b., rickman, r.w. 1987. studies of intact shoot root systems of field grown winter wheat ii. root and shoot developmental patterns as related to nitrogen fertilizer. agronomy journal, 79: 310-319. brandstreet, r.d. 1965. kjeldahl method for organic n. academic press. london. 85 p. brown, s.c., keatinge, j.d.h., gregory, p.j., cooper, p.j.m. 1987. effect of fertilizer, variety and location on barley production under rainfed condition in northern syria. i. root and shoot growth. field crops resources, 16: 53-66. buah, s.s., abatania, i.n., aflakpui, g.k.s. 2009. quality protein maize response to nitrogen rate and plant density in the guinea savannah zone of ghana. west african journal of applied ecology 16: 9-21. chesson, a. 1997. plant degradation by ruminants: parallels with litter decomposition in soils. in: cadisch g and giller k (eds) driven by nature: plant litter quality and decomposition. cab international, wallingford uk. constantinides, m., fownes, j.h. 1994. nitrogen mineralization from leaves and litter of tropical plants relationship to nitrogen, lignin and soluble polyphenol concentrations. soil biology and biochemistry. 26: 49-55. duncan d.b. 1955. multiple range and multiple ftest. biometrics. 11:1-42. el-gizawy, n. kh. b. 2009. effects of nitrogen rate and plant density on agronomic nitrogen efficiency and maize yields following wheat and faba bean. american-eurasian journal of agricultural and environmental sciences. 5(3): 378-386. giashuddin, m.m.,garrity, d.p., aragon, m.l. 1993. weight loss, nitrogen content changes, and nitrogen release during decomposition of legume tree leaves on and in the soil. nitrogen fixing tree research reports 2: 43–50. giller, k.e., wilson, k.j. 1991. nitrogen fixation in tropical cropping systems. cab international, wallingford, u. k.189p. giller, k.e. 2001. nitrogen fixation in tropical cropping systems, cab international, wallingford, uk, 2nd edition. p 423. hagerman, a.1988. extraction of tannin from fresh and preserved leaves. journal of chemical ecology. 2(2): 95121. oyebamiji et al. /journal of tropical forestry and environment vol. 07, no. 01 (2017) 54-64 63 handayanto, e, cadisch, g.,giller, k.e. 1994. nitrogen release from prunings of legume hedgerow trees in relation to quality of the prunings and incubation method. plant and soil. 160: 237248. handayanto, e, cadisch, g.g., giller, k.e. 1997. “regulating n mineralization from plant residue by manipulation of quality”. g. gadisch and k.e., giller (ed). driven by nature plant litter quality and decomposition. cab international, wallingford, 167-1674. jama, b.a., nair, p.k.r. 1996. decomposition and nitrogen mineralisation patterns of leucaena leucocephala and cassia siamea mulch under tropical semiarid conditions in kenya. plant and soil 179: 257-285. kang, b.t., caveness, f.e.o., tian, g., kolawole, g.o. 1999. long-term alley cropping with four hedgerow species on an alfisol in south western nigeria: effect on crop performance, soil chemical properties and nematode population nutrient cycling in agroecosystems. 54: 145155. mclaughlin, n.b., gregrorich, e.g., dwyer, l.m., ma, b.l. 2002. effect of organic and inorganic amendments on mouldboard plow draft. soil tillage res. 64, 211-219. mafongoya, p.l.,giller, k.e.,palm, c.a. 1998. decomposition and nitrogen release patterns of tree prunings and litter. agroforestry systems. 38:77-97. mugwe, j., mugendi, d., mucheru-muna, m., merckx, r., chianu, j.,vanlauwe, b. 2009. determinants of the decision to adopt integrated soil fertility management practices by smallholder farmers in the central highlands of kenya. experimental agriculture 45: 61-75. mugendi, d.n., nair, p.k.r. 1997. predicting decomposition patterns of tree biomass in tropical highland microregions of kenya. agroforestry systems. 35: 187-201. mugendi, o.n., nair, p.k.r., graetz, d.a. mugwe, j.n., neil, m.k.o. 2000. nitrogen recovery by alley-cropped maize and trees from 15 n-labelled tree biomass in the sub humid highlands of kenya. biology fertility soils. 31: 97-101. mungai, n.w., motavalli, p.p. 2006. litter quality effects on soil carbon and nitrogen dynamics in temperate alley cropping systems. applied soil ecology.31, 32-42. murwira, h.k.,mutuo, p.k., nhamo,n., marandu, a.e.,rabeson,r., mwale, m., palm, c.a. 2002. fertilizer equivalency values of organic materials of different quality. in integrated plant nutrients management in sub-saharan africa: from concept to practice, 113-152 (eds). oguntoyinbo, j.s.1983. a geography of nigerian development, heinemann educational books (nig.), jericho, ibadan 456 p. olujobi, o.j., oyun, m.b. 2013. nitrogen transfer from pigeon pea [cajanus cajan (l.) misllp.] to maize (zea mays l.) in a pigeon pea /maize intercrop. american international journal of contemporary research. 2(11): 115-120. palm, c.a. 1988. mulch quality and n dynamics in alley cropping systems in the peruvian amazon. phd thesis, north carolina state university, raleigh n.c. pp 33-40. palm, c.a. 1995. contribution of agroforestry trees to nutrient requirements of intercropped plants. agroforestry systems. 30: 105-124. patel, j.b., patel, v.j., patel, j.r. 2006. influence of different methods of irrigation and nitrogen levels on crop growth rate and yield of maize (zea mays l.). indiean journal crop science. 1(1-2): 175-177. peoples, m.b., herridge, d.f., ladha, j.k. 1995. biological fixation: ‘’an efficient source of nitrogen for sustainable agricultural production?’’ plant and soil,174(1-2): 3-28. sanginga, n., woomer, p.l. (eds) 2009. integrated soil fertility management in africa: principles, practices and development process. nairobi, kenya: tropical soil biology and fertility institute of the centre for tropical agriculture, 263 pp. sas institute 2000.statistical analysis systems, users guild, cary, n.c usa. 949 pp. silver, w.l., miya, r.k. 2001. global patterns in root decomposition: comparisons of climate and litter quality effects. oecologia. 129, 407419. 64 snapp, s. s., jones. r. b., minja, e. m., rusike, j., silim, s.n. 2003. “pigeon pea for africa: a versatile vegetable—and more,” horticultural science. 38(6): 1073–1079. teklay, t, nordgren, a., nyberg, g., malmer, a. 2007. carbon mineralization of leaves from four ethiopian agroforestry species under laboratory and field conditions. applied soil ecology. 35, 193-202. upadhyaya, k,sahoo, u.k., vanlalhriatpuia, k., roy, s. 2012. decomposition dynamics and nutrient release pattern from leaf litters of five commonly occuring homegarden tree species in mizoram, india. journal of sustainable forestry. 31(8): 711-726. vanlauwe, b, nwoke, o. c., sanginga, n. and merckx, r. 1996. impact of residue quality on the c and n mineralization of leaf and root residues of three agroforestry species. plant soil. 183, 221-231. vanlauwe, b., giller, k.e. 2006. popular myths around soil fertility management in sub-saharan africa. agriculture, ecosystems and environment.116: 34–46. vanlauwe, b., bationo, a., chianu, j., giller, k.e.,merckx, r.,mokwunye, u., ohiokpehai, o., pypers, p., tabo, r., shepherd, k.d., smaling, e.m.a.,woomer, p.l., sanginga, n. 2010. integrated soil fertility management. operational definition and consequences for implementation and dissemination. outlook on agriculture 39:17-24. 10 identification of vegetation change of lower u minh national park of vietnam from 1975 to 2015 p.t. khanh 1 and s.m.c.u.p. subasinghe 2* 1 department of environment, university of an giang, long xuyen city, vietnam. 2 centre for forestry and environment, department of forestry and environmental science, university of sri jayewardenepura, nugegoda, sri lanka. date received: 20-09-2017 date accepted: 10-12-2017 abstract the vegetation of the lower u minh is an important ecosystem as it contributes to preserrve the nature while providing many bebefits. it is also used as an excellent indicator for identifying early signs of ecosystem change in the entire area. in order for that, however, an effective method should be used to reevaluate the change occurred during the past years. use of remote sensing is the most effective method that serves for this purpose which was also used in the present study. in order to identify the vegetation change over a 40 years of time since 1975, three landsat (tm) satellite images (1975, 1995 and 2015) were taken to develop the base maps which were then compared to identify the vegetation change of the national park. using the base maps, six different vegetation types were identified using unsupervised and supervised classifications to build vegetation classification map with an overall accuracy of 86.33% and a kappa coefficient of 0.81. the results showed that multi-temporal landsat images with the average resolution bear the ability to assess the vegetation coverage changes. though the total extent of the national park has not been changed during the study period, the extents of its vegetation types changed in different manners. the grass cover changed from 155.57 ha in 1975 to 643.24 in 2015 while extent of water changed from 315.24 ha to 194.92 ha during the same period. the extents of the grass cover and water were 884.95 and 697.60 ha respectively in 1995. the melaleuca forest cover of different ages was also changed in significant manner during the study period. keywords: landsat, remote sensing, the lower u minh national park, ca mau 1. introduction human life is now threatened due to climate change, largely by the loss of vegetation cover of the earth. especially, the rainforests and related vegetation are in danger causing the potential loss of biodiversity. an estimated 7 million ha of forests are lost annually due to deforestation (fao, 2016). only 4 billion hectares of rainforests remain worldwide according to global forest resources assessment 2015 (rainforest action network, 2017). further, deforestation continues to be a major environmental issue which jeopardizes people’s livelihoods, threatens the existence of species, and intensifies global warming. thereby it continues to create severe social problems, sometimes leading to violent conflicts (butler, & rhett, 2007). the total forest area in vietnam is about 14,062 million hectares, which is about 40.84% of the total land area (huong, 2015). according to the ministry of natural resources and environment, the primeval forests of vietnam have seriously been reduced and only a very little is present today. such areas mainly exist as the protection forests, conservation zones, and most of the natural forests which are the only examples of primeval forests (tuan, 2009). *correspondence: upuls@sjp.ac.lk tel: +94 714450339 issn 2235-9370 print / issn 2235-9362 online © university of sri jayewardenepura khanh and subasinghe /journal of tropical forestry and environment vol. 7, no. 02 (2017) 10 -20 11 wetlands provide significant economic, social and cultural benefits for the living being. they also provide primary products such as pasture, timber, fish, food, drinking water, fresh air and aesthetics and support recreational and tourist activities. further, wetlands reduce the impacts of storm damage and flooding, maintain good water quality in rivers, recharge groundwater, store carbon, stabilise climatic conditions, protect biodiversity and control pest outbreaks (nsw, 2013). ca mau province of vietnam is one of the localities bears a large melaleuca forest area which is of 35,000 ha. it is distributed mainly in the districts of u minh, tran van thoiand thoi binh in two typical soil groups, viz., alkaline soil and peat (diem, 2013).with the large area of melaleuca forest, it acts as a green wall against the wind blows from the west sea and it is also considered as the green lung to keep the environment clean not only for ca mau city but also the whole mekong delta region. due to this importance, unesco listed the lower u minh as one of the biosphere reserves of the world on 26 th may, 2009. the lower u minh national park preserves spiritual and cultural values, acts as a historical monument of the region, provides opportunities for scientific research, sightseeing and tourism development. it also has the task of preserving genetic resources, re-creating the natural landscape (hiep, 2005). since the establishment of national park, the protection activities were uplifted to better conditions as it reduced frequent forest fires. however, fire eruption still occurs in the area mainly due to the existence of about 1,000 households with approximately about 5,000 people living adjacent to the lower u minh national park as forest-dependents. those families distributed along the east-west and south canal route forms the border surrounding the lower u minh (board of the lower u minh national park management, 2015). these dwellers are farmers or hired laborers with very low income and therefore, they have continued to exploit the forest for non-timber products such as honey, fish, snakes, turtles and other animals. these activities influence the management for forest protection mainly due to eruption of fire due to the hot weather. fires are more frequent in summer and it obviously makes the vegetation cover change in the park (board of the lower u minh national park management, 2015). many studies were conducted on different aspects in the lower u minh national park in the past. its plant diversity and ecosystem management were studied by tan (2005) and hiep (2005) respectively while studies were conducted on fire eruption by hiep (2005). vegetation growth and peat layer were studied by hoa et al., (2009), quoi (2014) and hong et al., (2015). however, a study on the temporal change of the vegetation structures had not been done in the past for the lower u-minh national park. availability of such information is vital for the park managers and for the annual reports which are currently prepared by various relevant agencies based on traditional mapping methods which are inaccurate as the scale is not considered. further, the information generated by a proper mapping study using remote sensing and gis activities would help the management board of the lower u minh national park to understand the forest resources change through different stages. this will also act as a scientific database to help the management to conserve the national park. therefore the present study was conducted in the lower u minh national park with the objectives of identifying the present vegetation distribution and mapping the vegetation cover change over the years of 1975, 1995 and 2015using remote sensing and gis techniques. remote sensing and gis techniques have been widely used in the past by many researchers to identify the vegetation change (billingsley, 1984; xie et al., 2008; gandhi et al., 2015). remote sensing helps the researchers to observe the history of the vegetations through the satellite images taken via various bands of the spectrum which can be enhanced by algorithms such as ndvi (gandhi et al., 2015). gis acts as a valuable tool to overlay the different images produced for different periods in the past to identify the changes. 12 2. methodology 2.1 characteristics the study area the lower u minh national park belongs to u minh and tran van thoi districts of ca mau province in vietnam. the total extent of the park is estimated to be about 8,476 ha. it is located between 9 o 12’30” to 9 o 17’41” n and 104 o 54’11” to 104 o 59’29” e (figure 1). the average temperature in the area is 26.5 0 c and the average annual precipitation is 2,360 mm. its terrain is relatively flat and the average elevation varies from 1 to 1.5 m above sea level. the main soil types are peat and clay with alum sub-soils dominating in water logging areas. figure 1: location of the lower u minh national park (right) and mekong delta (left). figure 2: layout of sample plots in the lower u minh national park. due to the presence of dyke systems in the area, lower u minh national park is not affected by the diurnal tidal of the west sea. however, the area is flooded from 0.1 to 1 m during the rainy season for 5-6 months from june to november in each year. the amount of water in the forest can be adjusted, lowered or stored in each zone by regulating water through culverts. the vegetation of the lower u minh national park dominates with melaleucaca juputii belongs to myrtaceae family. 2.2 data collection a total of 45 plots of 40x40 m were used to study the vegetation types and species present in the national park. out of 45, 33 plots were laid in the plantation melaleuca forest of various age classes and 12 plots were laid in natural melaleuca forest area (figure 2). data on plant community composition, species abundance and relevant environmental characteristics were collected from those plots. in addition, ground cover percentage of the plants, plant/tree height and species diversity were also recorded. the species were identified at the field based on their morphological characteristics using the taxonomy guides of ho (1993). 2.3 map building three landsat (tm) satellite images of different bands for 1975, 1995 and 2015 were downloaded from http://earthexplorer.usgs.gov and those were clipped to the study area basedon the respective land use maps. these multiband images were re-projected to utm zone 48 north, wgs-84 datum. khanh and subasinghe /journal of tropical forestry and environment vol. 7, no. 02 (2017) 10 -20 13 thereafter, each image was exported to the erdas 2014 ex software and an image difference tool was used to detect the changes between 1975, 1995 and 2015 based on the normalized difference vegetation index (ndvi) as it is a useful method for determining plants depending on the distribution density. ndvi is functionally equivalent to simple band ratios of tm images and can be described as ndvi = (nir band red band)/ (nir band + red band), where: nir band = spectral reflectance for band 4; red band = spectral reflectance for band 3. use of ndvi for this purpose has been well-justified by gandhi et al. (2015). interpretation keys are then established followed by unsupervised classification which was first used to produce land cover classes for the study area using the isodata algorithm in erdas er mapper, which classifies the image into a pre-selected number of classes using an iterative calculation procedure to ensure maximum statistical separability based on the spectral data. this activity was able to identify 6 vegetation classes, viz., soil, water, grass, natural melaleuca, plantation melaleuca and regenerated melaleuca with a 0.98 confidence interval. secondly a supervised classification was performed by using the maximum likelihood classification tool. this algorithm uses the means and variances of the training data to estimate the probability that a pixel is a member of a class. the pixel is then placed in the class with the highest probability of membership. a confusion matrix was then built and image interpretation was completed based on the image selected according to the classification system. the resulting map is used to check and evaluate the accuracy by the field survey. in this study, random sampling method was used to evaluate classification accuracy. image interpretation and data processing were conducted for the coverage maps of 1975, 1995 and 2015 by using erdas software. ground verification activities were tested with the field data. arcgis 10.2 was finally used to overlay the maps of different years to compute the area of the object classes. 3. results 3.1 survey results in the field the lower u minh national park has been dominated by melaleuca cajuputii trees with a grass community and vines. the melaleuca forest is 88.64% of the total area of the national park in 2015 and rest was comprised of bare soil, canals and grassland. the ground survey revealed that there are 104 plant species of natural plants belonging to 48 different families. among them, grass and liana are the most dominant types. although known as melaleuca forest, there are 11 other tree species (annona glabra, alstonia spathuluta, llex thorelii, trema orientalis, acacia auriculiformis, ficus microcarpa, f. pisocarpa, morus alba, eugenia cumini, euodia lepta and premna intergrifolia) found in the forest area. apart from that, 4 shrub species, 4 herbaceous species, 38 grass species, 27 liana species, 14 aquatic weed species, and 6 fern species were recorded. the meleluca area could be divided into two sub-zones as natural zone and plantation zone. 3.2 natural melaleuca forest zone (grown on the peat land) melaleuca trees growing naturally covered an extent of1, 844.46 ha in 2015 which is accounted for 21.76% of the total area. it was distributed in the southwest of the national park (figure 2). 59 flora species belonging to 34 families were identified in this forest, of which there were 9 species of woody plants, 4 shrubs, 4 herbaceous species, and 26 species of liana, 6 fern species and 10 species of grass. apart from dominant melaleuca tree species, some other plants such as alstonia spathulata (apocynaceae), llex cymosa (aquifoliaceae), euodia lepta (rutaceae) and syzygium cumini (myrtaceae) were recorded in large numbers. further, this forest type is characterized by an abundance of ferns, of which the two most common species are stenochlaena palustris and nephrolepis falcate. shrub species 14 are glochidion littorale, senna alata, melastoma affine and phyllanthus reticulatus.the melaleuca density was low in the areas of the dominant grass and vines. the highest number of melaleuca trees was fallen into the dbh category of >20 cm accounting to 31.19% with the average height of 14.78 m. trees of height >20 m and dbh>60 cm were also found, but few in numbers. the highest density of melaleuca is 675 trees/ha while the lowest density is 318.75 trees/ha. the average density was 528.65 trees/ha and the depth of the peat layer was 1.2 m. 3.3 plantation melaleuca zone (grown on the clay soil) the melaleuca plantation area is 5,668.87 ha in 2015, accounted for 66.88% of the total area of the national park and this forest type usually appears at the outer edge of the peat (figure 2). the regenerated melaleuca after fires seared away on the layers of primitive peats with the total area of 1,653.97 ha in the north and east of the national park which is accounted for 19.51% of the total extent. the plantation melaleuca is longed to six age classes, viz., 2, 4, 6, 8, 10, and 12 years. the average density of melaleuca in this zone was 6,285.71 trees/ha with the average ground cover of 72.87%. the average height was 11.74 m and the average dbh was 9.19 cm. phragmites vallatoria is the next common species with the average coverage of 16.1%. the rest was fern and liana. the total number of species in the plantation zone was 38 of which 4 species are woody plants, 4 shrubs, 3 herbaceous species, 5 fern and 10 liana species. in addition, 12grass species were also found. grass species were usually present in wet areas along the canals and bogs where previously melaleuca forests were burn down by humans. besides the two dominant species of eleocharis dulcis and phragmitex sp., this habitat also had 38 other grass species. vallatoria reeds grow along the main road from the front gateway of the national park to the back gate and along the banks of canals on the dyke with the total reed area of approximately 5, 960, 166 m 2 . height of reeds can reach up to 4 m, forming single-species areas. further, eleocharis dulcis was found to be common along the routes distributed throughout the park along with reed grassland. the total area of e. dulcis grassland was estimated to be 1,190.000 m 2 . it was usually the dominant species, with density of about 95%, and height about 30-70 cm. besides e.dulcis, other species such as cyperus extentelatus, cyperus exaltatus, cyperus compactus, eleocharis attropurea, phragmites karka, ludwigia adscendens, ceratopteris thalictroides, pistia stratiotes, lemna minor and nymphaea nouchali were also present. the dominant species found in marsh were nymphaea nouchali, pistia stratiotes, salvinia cucullata, ludwigiaadscendens and hydrilla verticillata. these plants distribute in to dense floating arrays covering the entire water surface of the area forming dense-mat like vegetations. in addition, other plants species also appeared along with this species. among them the common species were eichhornia crassipes, eleocharis dulcis, ipomoea aquatic, ludwigia adscendens, leersia hexandra and commelina diffusa. apart from that, aquatic species such as ceratopteris thalictroides; ludwigia adscendens; eichhornia crassipes and monochoria vaginalis were found in the swamp. the total area of swamps was estimated to be 833,000 m 2 in extent. plant groups found in canals which were man-made were quite diverse. vigna luteola, commelina diffusa, cyperus elatus and ischaemum rugosum were found along the canal banks. utricularia aurea, hydrilla verticillata, pistia stratiotes, salvinia cucullata and eichhornia crassipes were submerged or floating species in the canals. many channel segments in the core area were heavily covered with dense floating carpet-like eichhornia crassipes and pistia stratiotes. canal segments in the outer core areas often do not have this situation due to better water flow. the total canal area is 199 ha. khanh and subasinghe /journal of tropical forestry and environment vol. 7, no. 02 (2017) 10 -20 15 3.4 map analysis the resultant ndvi values after classification of the study site into 6 vegetation classes are given in table 1. ndvi values of negative or zero were placed where there was absolutely no presence of vegetation, e.g., bare soil, canals, flooded soil. among them natural forest had the highest ndvi value of 0.368 to 0.722 (table 1). table 1: ndvi index for the vegetation classes of the lower u minh national park. no vegetation classes ndvi 1 water 0.951 to -0.129 2 bare soil 0.256 to 0.115 3 grass 0.194 to 0.282 4 regenerated forest (< 9 years) 0.232 to 0.322 5 plantation forest (9-13 years) 0.312 to 0.387 6 natural forest (>13 years) 0.368 to 0.722 the three vegetation cover maps built for the lower u minh national park for 1975, 1995 and 2015 are given in figure 3a-3d respectively. however, according to the results, map analysis using ndvi calculation is found to have some drawbacks. for instance, the ndvi values of grass and regenerated forest were approximately similar. therefore, the interpretation of these two classes was initially not accurate. however, it was corrected by field observations with the help of a high quality gps device. further, an error matrix was used to accurately evaluate the results of the classification. the results of accurate assessment of vegetation classification based on the actual data set for the year 2015 are shown in table 2. according to table 2, the accuracy of the classification of six vegetation layers by the supervised classification method ranged from 75% to 90%. most classes, however, had the accuracy interpretation over 80%, except for grass and regenerated melaleuca (<9 years) which had the classification accuracy of 75% and 79%, respectively. table 2 also indicates that the overall classification accuracy is 86.33% and the overall kappa coefficient is 0.81 proving that the overall quality of image interpretation is high. table 2: assess the accuracy of the landsat image interpretation of vegetation cover classification in the lower u minh in 2015. no class name producers accuracy users accuracy 1 unclassified -- 2 water 93.33% 87.50% 3 bare soil 75.00% 90.00% 4 grass 75.00% 75.00% 5 regenerated forest (< 9 years) 82.35% 79.25% 6 plantation forest (9-13 years) 90.35% 89.57% 7 natural forest (>13 years) 92.68% 82.61% overall classification accuracy = 86.33% overall kappa statistics = 0.8078 final results of the image classification of the national park for 2015 are given in figure 3d. the status of vegetation cover area of the study area in the period of 1975-2015 using satellite imagery is illustrated in figure. 4. the area of natural melaleuca (>13 years) decreased in 1995 compared to 1975 again increase in 2015, which is however, less than that of 1975. plantation grown melaleuca in the age 16 of 9-13 show an increase which became the highest in 2015. the area of regenerated melaleuca (<9 years) increased in 1995 compared to 1975, again decreased in 2015. figure 3b: the vegetation cover map of the lower u figure 3a: the vegetation cover map of the lower u minh in 1995 by unsupervised classification. minh in 1975 by unsupervised classification. figure 3c: the vegetation cover map of the lower u figure 3d: the vegetation cover map of the lower u minh in 2015 by unsupervised classification. minh in 2015 by supervised classification. khanh and subasinghe /journal of tropical forestry and environment vol. 7, no. 02 (2017) 10 -20 17 area (ha) 4500 4,014.90 4000 3,725.81 3500 3,171.27 3000 2,555.29 2500 1,844.46 2000 1,653.97 1,444.39 1,428.65 1,289.52 1500 884.95 828.69 1000 697.60 643.24 315.24 446.45 500 194.92 124.58 155.57 0 water bare soil grass regenerated plantation natural forest forest(<9 forest(9-13 (>13years) 1975 1995 years) 2015 years) figure 4: the vegetation cover area of the study area, 1975-2015. % 50 42.10 40 37.59 30 20 6.72 13.80 6.53 10 6.39 5.75 0 -0.19 -0.64 -4.51 -1.42 regenerated natural forest -10 water bare soil grass plantation -8.14 forest(<9 forest(9-13 (>13years) -10.66 years) -20 -15.39 -15.58 years) -15.68 -30 -24.46 -22.21 1975-1995 1995-2015 1975-2015 figure 5: the changes percentage of vegetation area in the national park, 1975-2015. change of the vegetation cover classes in the national park is high during the study period (figure. 5). from 1975 to 1995, the area of plantation melaleuca (9-13 years) and natural melaleuca (>13 years) decreased by 4.51% and 22.21% respectively from 1975 to 1995.the reason for this could be the frequent forest fires occurred in that period. moreover, the law enforcement was not strict during the same period and therefore many local people exploited melaleuca forest for wood and firewood. after the fires, park management took actions to replant melaleuca forest on burned forest land and thereby it regenerated together with weeds. therefore, the area of regenerated melaleuca forest (<9 years) increased to 13.8%. 18 4. discussion remote sensing based image analysis is especially appropriate over the traditional methods such as field surveys, literature reviews, map interpretation and collateral and ancillary data analysis for reconnaissance mapping and information monitoring for different types of wetlands spreading over large geographic areas (langley, 2001; nordberg, 2003). successful use of remote sensing for detailed interpretation in wetland studies depends mainly on the spatial resolution of images. the present study also proved that remote sensing and gis techniques is an optimal solution to the current forest cover mapping as it allowed a better comparison of vegetation change over the selected period of time. landsat image information extraction was carried out using unsupervised and supervised classification in this study to produce vegetation cover classes. maximum likelihood classification (mlc) showed better results when compared with unsupervised classification for distinguishing vegetation classes. supervised classification is depending on the user definition for training areas, aerial photography, and field verification which all were proven to be useful for the selection of vegetation classes. the six vegetation class-output map built by supervised classification using landsat tm image analysis for 2015, showed high accuracy with the analysis of aerial photography for the same year. however, there was a problem in separating vegetation classes larger than the pixel size (30m×30m), such as waterlogged soil and water class; grass and melaleuca, especially in selecting a training area because of the difficulty of distinguishing between classes producing similar colors of the reflection. this could lead them being coded with the same color in the image. landsat images have been applied in vegetation mapping mainly at regional scales. since landsat has a long history of dataset, it is very helpful to map long-term vegetation cover and study the spatiotemporal vegetation changes. for example, nearly 20-year continuous landsat tm/etm+ image datasets (19 images) covering western oregon were used to detect and characterize continuous changes in early forest succession (schroeder, 2006). landsat tm images, striding a long period of time from 1986 to 2002, were used to conduct quantitative analyses of wetland landscape patterns and their dynamic changes in the estuary of the minjiang river (zheng, 2006). because of the different characteristics of spectral sensors (i.e. tm and etm+) in the landsat image series, it is necessary to correct the spectral reflectance between images acquired by those sensors. this is especially necessary in long-term vegetation cover monitoring research where both landsat tm and etm+ images are used (yichun,2008). due to the limitation of spatial resolution, landsat products are usually used to map vegetation at community level (domaç, 2006). a few studies were conducted in vietnam on the application of remote sensing and gis techniques for the establishment of forest cover maps though the extent of remote sensing information was limited. the use of ndvi was recognized by those studies as a useful method to detect the vegetation differences. thom (2014) successfully used ndvi method for satellite image classification for thanh mai commune of cho moibac can (thom, 2014). the same method was successful for the present study which was proven by the kappa index of 0.81. thanh (2013) also used the same method of classification with 2006 landsat image data for establishing 7 different vegetation classes which had the kappa index of 0.7 which was lower than the kappa index of the present study (thanh, 2013). six vegetation classes for tram chim national park of dong thap for the period of 1995 to 2013was done by supervised classification with spot 1995 and astor 2013 and the resultant kappa coefficient was 0.8 (tien, 2014). these results showed that the interpretation of landsat images provides similar results to that of spot and aster images. javascript:; khanh and subasinghe /journal of tropical forestry and environment vol. 7, no. 02 (2017) 10 -20 19 5. conclusions multi-temporal landsat images with a 30m spatial resolution can be used for the assessment of vegetation coverage changes with guaranteed results. the present study showed that there were 104 species of natural plants, belonging to 48 different plant families: 11 species of woody trees, 4 shrub species, 4 herbaceous species, 38 grass species, 27 liana species, 14 aquatic species and 6 fern species. natural melaleuca forest covered an area of 1,844.46 ha in 2015 which was accounted for 21.76% of the total area. the rest was planted on clay, distributed over the remaining area (66.88%) and the bare soil, canals land, grass land were 11.36%. the information elaborated in the present study can effectively be used to identify the areas of the lower u-minh national park to be used for obtaining benefits and the areas that should be conserved. for example, the details of the different age classes of planted m. cajuputi are helpful to estimate the tangible benefits in accordance with the policies of the national park use. further the details of the other areas can be used for the conservation management activities. references billingsley, f.c. 1984. remote sensing for monitoring vegetations: an emphasis on satellites. in the role of vegetations in the global carbon cycle: measurement by remote sensing (g.m. woodwell), john wiley and sons. board of the u minh national park management. 2015. the deep interview results of status of forest management and protection. butler, rhett a. 2007. primary rainforest richer in species than plantations, secondary forests: (https://news.mongabay.com/2007/07/forest-disturbance-reduces-biodiversity-in-the-amazonrainforest). accessed on 02 nd july 2007. diem, p. 2013. discovery of the lower u minh. ( http://www.camau.gov.vn/wps/portal/!ut /p/a0/04_sj9cpyk) accessed on 01 st december 2013. domaç, a., süzen, m.l. 2006. integration of environmental variables with satellite images in regional scale vegetation classification. international journal of remote sensing, 27: 1329-1350. fao. 2016. global forest resources assessment 2015: how are the world’s forests changing? food and agricultural organisation of the united nations, rome. gandhi, m., parthiban, s., thummalu, n., christy, a. 2015. ndvi: vegetation change detection using remote sensing and gis: a case study of vellore district. procedia computer science, 57: 11991210. geist, h.j.,lambin, e.f. 2002. proximate causes and underlying driving forces of tropical deforestation. american institute of biological sciences, 52(2): 143-150. ho p.h. 1993. an illustrated flora of vietnam.the south vietnamese ministry of education, vietnam. hong, t.t., long, n.b., ni, d.v., be, n.v. 2015. peat thickness affecting growth indexes of the melaleuca forest in the u minh ha national part, ca mau province. journal of science, can tho university,40: 92-100. huong, d. 2016. the average coverage percentageof vietnamese forest (http://baochinhphu.vn/hoatdong-dia-phuong/do-che-phu-rung-viet-nam-dat-4084/283007.vgp). accessed on 1 st august 2016. keenan, r., reams, g., freitas, j., lindquist, e., achard, f., grainger, a., 2015. dynamics of global forest area: results from the 2015 global forest resources assessment. forest ecology management, 352: 9-20. langley, s.k.,cheshire, h.m.,humes, k.s., 2001. a comparison of single date and multi-temporal satellite image classifications in a semi-arid grassland. journal of arid environment, 9: 401-411. http://news.mongabay.com/2007/0702-gardner.html https://news.mongabay.com/2007/07/forest-disturbance-reduces-biodiversity-in-the-amazon-rainforest/ https://news.mongabay.com/2007/07/forest-disturbance-reduces-biodiversity-in-the-amazon-rainforest/ https://news.mongabay.com/2007/07/forest-disturbance-reduces-biodiversity-in-the-amazon-rainforest/ http://www.camau.gov.vn/wps/portal/!ut/p/a0/04_sj9cpyk http://www.camau.gov.vn/wps/portal/!ut/p/a0/04_sj9cpyk http://baochinhphu.vn/hoat-dong-dia-phuong/do-che-phu-rung-viet-nam-dat-4084/283007.vgp http://baochinhphu.vn/hoat-dong-dia-phuong/do-che-phu-rung-viet-nam-dat-4084/283007.vgp http://baochinhphu.vn/hoat-dong-dia-phuong/do-che-phu-rung-viet-nam-dat-4084/283007.vgp 20 nsw, 2013. why are wetlands important? (http://www.environment.nsw.gov.au/wetlands/whyarewetlandsimportant.htm).accessedon28 th novemb er 2017. nordberg, m.l.,evertson, j., 2003. vegetation index differencing and linear regression for change detection in a swedish mountain range using landsat tm and etm+ imagery.land degradation & development, 16: 139-149. quoi, l.p. 2014. peatlandassesment in the u minh ha national park, ca mau province. institute for environment and natural resource national university at ho chi minh city.snvnetherlands development organisation redd+ programme. ha noi, vietnam. rainforest action network, 2017. how many trees are cut down every year? (https://www.ran.org/how_many_trees_are_cut_down_every_year)accessed on 06 th march, 2017. schroeder, t.a.,canty, m.j,yang, z. 2006. radiometric correction of multi-temporal landsat data for characterization of early successional forest patterns in western oregon.remote of sensing environment, 103:16-26. tan, d.t. 2005. ca mau flooded forest ecosystem. (http://vafs.gov.vn/vn/2005/07/he-thuc-vat-rung-ngapca-mau/). accessed on 06 th july 2005. thanh, h.x. 2013. establishment of vegetation map based on remote sensing image analysis, msc thesis. water resources university, vietnam. the nature conservancy. 2015. facts about rainforests: ( https://www.nature.org/ourinitiatives/.../rainforests/rainforests-facts.xml).accessed on 19 th october 2015. thom, t.t., que, p.t. 2014. using remote sensing data and gis to establishment of forest status map at the scale of 1:10.000. journal of forest science & technology, 4: 161-168. tien, p.d. thang, t.n. duong, l.v, 2014. mapping change vegetation cover at tram chim national park, dong thap, 1995-2013. proceedings of the nationwide gis application workshop in vietnam, 2: 615-623. tuan, h.c. 2009. overview of forest protection in vietnam and solutions of forest protection. forest protection department-ministry of agricultural and rural development: (http://www.kiemlam.org.vn/desktop.aspx/list/so12/tong_quan_ve_bao_ve_rung_viet_namva_n hung_giai_phap_bao_ve_rung/). accessed on 06 th january 2009. xie, y., sha, z., yu, m. 2008. remote sensing imagery in vegetation mapping: a review. journal of plant ecology, 1: 9-23. yichun, x., zongyao, s., mei, y., 2008. remote sensing imagery in vegetation mapping: a review. journal of plant ecology, 1: 9-23. zheng, c.h.,zeng, c.s.,chen, z.q.2006. a study on the changes of landscape pattern of estuary wetlands of the minjiang river,wetland science,4: 29-35. https://www.ran.org/how_many_trees_are_cut_down_every_year http://vafs.gov.vn/vn/2005/07/he-thuc-vat-rung-ngap-ca-mau/ http://vafs.gov.vn/vn/2005/07/he-thuc-vat-rung-ngap-ca-mau/ http://vafs.gov.vn/vn/2005/07/he-thuc-vat-rung-ngap-ca-mau/ https://www.nature.org/ourinitiatives/.../rainforests/rainforests-facts.xml http://www.kiemlam.org.vn/desktop.aspx/list/so12/tong_quan_ve_bao_ve_rung_viet_namva_nhung_giai_phap_bao_ve_rung/ http://www.kiemlam.org.vn/desktop.aspx/list/so12/tong_quan_ve_bao_ve_rung_viet_namva_nhung_giai_phap_bao_ve_rung/ javascript:; javascript:; _____________________________________________ *correspondence: murthy_ylk@yahoo.co.in issn 2235-9370 print/issn 2235-9362 online © university of sri jayewardenepura 108 altitude and ecological distribution of genus litsea (lauraceae) in western ghats of karnataka, india s.g. srinivas and y.l. krishnamurthy* department of p.g studies and research in applied botany, kuvempu university, karnataka, india date received: 12-04-2019 date accepted: 12-12-2019 abstract india is a subcontinent in the world with varied climatic regions, topographic variation results in the very diverse ecological diversity. litsea is a largest genus in the family lauraceae differentiated by its dioecious nature, distributed in tropical and subtropical regions which is influenced by some environmental factors. present research work focussed on distribution of genus in the central western ghats of karnataka, india. litsea species were collected from 2013 to 2018 in different sampling sites. a total of 12 species were identified and reported from this region. the diversity indices of litsea vary from species to species as well as region to region. l. floribunda is frequently distributed in all the study sites and it showed highest density when compared with other species, whereas, l. deccanensis distributed only in sakaleshpur region and it showed lower diversity. the highest number of litsea species occurred in sakaleshpur region (10 species) and mullayyanagiri region having only one species that is l. floribunda. the results indicate that litsea distribution and diversity is rich in moderate rainfall regions of western ghats. the macro and micro nutrients of the soil in the study area reflects the distribution of the genus. there is a gradual increasing in tendency of the species richness with increasing elevation when compared with lower elevated regions. the genus also showed more sensitive and positive association with the elevation factor. keywords: dioecious, elevation, nutrient, rainfall, soil 1. introduction the genus litsea consists of about 400 species which is largest genus in the family lauraceae differentiated by its dioecious nature, distributed in tropical and subtropical asia, australia, new zealand, north america and subtropical south america (chaing et. al., 2012). in india, about 45 species occur in evergreen and semi evergreen forests of western ghats of peninsular india and eastern himalayas. among 45 species 18 species are endemic to south india (bhuniya et al., 2010). the genus litsea shows higher distribution in north-eastern states such as meghalaya, manipur, assam, arunachal pradesh and sikkim. in south india the species distributed in tamil nadu, kerala, karnataka, maharashtra respectively. twelve species of litsea are reported in karnataka (saldanha, 1984). most of the species distributed in western ghats areas, where only two species found in other than western ghats regions. six species found in andaman nicobar islands and only one species reported from gujarat (bhuniya et al., 2009). litsea trees are distributed in an altitude range of 600-2500 m, some of the endemic litsea species grow particularly in some geographical regions, litsea sikkimensis, l. oreophilla, restricted to sikkim, l. membranifolia and l. mishmiensis confined to arunachal pradesh, l. travancorica only from kerala, l. ghatica restricted to western ghats parts of karnataka, kerala and l. leiantha confined to andaman and nicobar islands (bhuniya and mukherjee, 2012). doi: https://doi.org/10.31357/jtfe.v9i2.4473 srinivas and krishnamurthy /journal of tropical forestry and environment vol. 9, no. 02 (2019) 108-119 109 in india very limited research work has been done over the ecological diversity of litsea (saldanha, 1984; bhuniya, 2009, 2010; ganesan, 2011; mishra and naidu, 2013; robi et al., 2015). in the world scenario, recently published taxonomic revisions published from thailand with 35 species (ngernsaengsaruay et al., 2011), nepal with 11 species (pendry et al., 2011) and in china with 74 species (huang et al., 2008). biodiversity maintains some essential ecosystem functions (brilliant et al., 2012). the immense biodiversity generates a variety of natural resources which helps in sustain the life of local communities. understanding species diversity and distribution patterns is important for helping managers to evaluate the complexity and resources of these forests, trees from the major structural and functional basis of forest ecosystems and serve as indicators of changes at the landscape scale (kumar et al., 2006). discussing and study the diversity of a particular genus or in group to get some idea about the genus and present status of genus leads to conservation. field collection, base line data, generation of digital databases, monograph writing, exploration of genetic diversity and development of sacred forests with special reference to particular forest or genus, initiation of gene and seed banks, establishment of micro propagation lead to conservation of the species. different climatic and topographic gradient results in varied vegetation types, evergreen to semievergreen, moist deciduous to dry deciduous forest types, leads to diverse flora and fauna (ramesh et al., 1997). the species diversity and distribution in the tropics varies dramatically from place to place because of some environmental, edaphic and topographic factors (pitman et al., 2002). present study focussed on influence of ecological factors and altitudinal factors on distribution of litsea species in central western ghats. 2. materials and methods 2.1 study area study area of our research is central western ghats of karnataka. western ghats is the major biodiversity hot spot in india. karnataka is situated at angle of central western ghats. karnataka is one of the major state in india that covers around 191,976 km2 and contribute 5.83 per cent of total geographical area of india. the state is situated in deccan plateau and bordered by the arabian sea to the west, maharashtra to the north, goa to the northwest, andhra pradesh-telangana to east, kerala to the southwest and tamil nadu to the southeast. about 21 per cent of total geographical area of the state is covered by different forest types. western ghats regions of karnataka include seven districts, shivamogga, chikkamagaluru, hassan, kodagu, udupi, dakshina kannada and uttara kannada districts. the major vegetation types include tropical evergreen forests, semi evergreen forests, deciduous forests, dry deciduous forests, scrubby forests, shola and savanna grasslands. our preliminary survey revealed that the litsea species are distributed in the evergreen and semi evergreen forests; hence we are restricting our survey to the forests of seven districts of western ghats. 110 figure 1. map of the central western ghats regions of karnataka from where the samples were collected. 2.2 field survey and collection of litsea species field survey was conducted frequently in evergreen, semi evergreen and deciduous forests in western ghats of karnataka in eight study sites, such as kemmannugundi (kmd), mullayyanagiri (mlg), madikeri (mdk), kodachadri (kdc), agumbe (agm), karkala (krk), sakaleshpur (skp) and yellapur (ylp) region. stratified random sampling method was used to collect the tree data. a standard size, 250×4 m belt transects were laid in each study area covering 3 transects in each study sites. in each study site available litsea species were collected. morphological characters were observed and noted among the different populations of litsea genus. the litsea species collected were identified through standard floras (gamble, 1998; saldanha, 1996). this was supplemented with literature survey and study of herbarium specimens deposited at west region herbarium centre pune, botanical survey of india and herbarium jcb, centre for ecological sciences (ces), indian institute of science bengaluru. digital images of type specimens were referred from the royal botanical gardens, kew london, uk to confirm the identity of the species. herbarium specimens of all the collected species were deposited in herbarium jcb, centre for ecological sciences, indian institute of science bengaluru, india. all the important distinguishable taxonomic characters of each species were tabulated. based on these important characters key for identification of the species were prepared. srinivas and krishnamurthy /journal of tropical forestry and environment vol. 9, no. 02 (2019) 108-119 111 2.3 influence of ecological factors on distribution to study the influence of environmental factors on distribution of litsea species like temperature, rain fall were recorded available in the field. climatic data is also obtained from www.worldclimate.org website. topographic factors like latitude, longitude and altitudes of sampling sites were noted by using hand held gps (garmin etrex, usa). temperature was recorded using digital thermometer. in each study site the data was used to correlate with species distribution. the edaphic factors were studied by collecting the soil that occurs in all the study sites. different types of soil like loamy soil, reddish to brown, clayey loam to lateritic soil, fertile red loamy soil samples were collected. in all the study sites soil samples were collected from a rooting depth of 15 cm at each site. samples were air-dried, crushed using a pestle and mortar and then passed through a screen before analysis. standard methodology was followed for estimating soil salinity, ph, chemical nutrients of this collected soil samples tested in laboratory. 2.4 species distribution modelling map of litsea more number of species were distributed in western ghats of south india. to know the litsea species distribution throughout the western ghats predicted a species distribution map along the western ghats using climatic parameters by maxent modelling method. the important climatic parameters such as annual mean temperature, annual rainfall, mean precipitation in different months across the year. graphical information system (gis) and species mapping is an advanced tool for making species distribution models of different species of litsea in western ghats of india. species distribution range of each species topographic data of 12 species of litsea in karnataka across the eight study sites was used to generate the species distribution map along the western ghats of india. 3. results and discussion 3.1 diversity indices and ecology of genus litsea a total of twelve species comprised litsea bourdillonii, l. coriacea, l. deccanensis, l. floribunda, l. ghatica, l. glabrata, l. glutinosa, l. laevigata, l. mysorensis, l. oleoides, l. stocksii, l. wightiana were identified from our research study area (table.1). litsea floribunda, l. stocksii, l. wightiana, l. laevigata species were distributed abundantly when compared with other species. litsea ghatica, l. coriaceae and l. deccanensis are rare species to western ghats of karnataka. table 1: name of all the species occur in central western ghats of karnataka. the diversity indices of litsea vary from species to species as well as region to region. all the twelve species of litsea distributed in different locations. l. floribunda is frequently distributed in all the sl. no. species name field collection number voucher deposition number 1 litsea bourdillonii kuabl 1001 hjcb-n-0282 2 litsea coriacea kuabl 1002 hjcb-n-0283 3 litsea deccanensis kuabl 1003 hjcb-n-0284 4 litsea floribunda kuabl 1004 hjcb-n-0285 5 litsea ghatica kuabl 1005 hjcb-n-0286 6 litsea glabrata kuabl 1006 hjcb-n-0287 7 litsea glutinosa kuabl 1007 hjcb-n-0288 8 litsea laevigata kuabl 1008 hjcb-n-0289 9 litsea mysorensis kuabl 1009 hjcb-n-0290 10 litsea oleoides kuabl 1010 hjcb-n-0291 11 litsea stocksii kuabl 1011 hjcb-n-0292 12 litsea wightiana kuabl 1012 hjcb-n-0293 112 study sites and it showed highest density when compared with other species, whereas, litsea deccanensis distributed only in sakaleshpur region and it showed lower density. the highest individuals of litsea species occurred in sakaleshpur region (10 species) and mullayyanagiri region having only one species that is litsea floribunda. table 2: diversity indices of genus litsea in all the study sites of western ghats. litsea is frequently distributed in all the study sites. highest density was found in kemmannugundi region (48.40) and lower in karkala region (13.0). kemmannugundi region showed higher abundance when compared with other study sites whereas, madikeri, kodachadri and sakaleshpur region showed similar abundance values. relative frequency was higher in agumbe region and lower in sakaleshpur region. the genus litsea covers the more basal area in mullayyanagiri (1,904.79) and low in karkala (58.15) region (table 2). apart from ecological parameters with edaphic factors, the role of other associated species is very prominent in the growth, development and evenness of a species. the dominant companion tree species are laural members such as cinnamomum, neolitsea and cryptocarya. most of the species representing the family lauraceae (12 species) due to the preference of favourable environmental factors in all the study sites. it is evident that lauraceae is the dominant family of the companion species in the jaintia hills in north east india (upadhaya et al., 2003). figure 2. shannon and simpson diversity index in different study sites of western ghats of karnataka. study sites frequency den/ transect abundance rf rd ra ivi a/f ratio basal area m2/ha kmd 0.71 48.40 56.01 32.40 56.82 49.13 86.59 100.00 928.40 mlg 1.00 47.67 47.67 10.00 50.00 44.90 60.00 4.77 1,904.79 mdk 1.00 41.66 41.66 37.52 74.86 68.14 112.38 4.45 910.08 kdc 0.87 39.95 42.71 43.90 59.36 53.79 101.01 5.91 408.30 agm 0.66 37.00 48.00 70.16 35.55 53.63 45.07 87.16 176.34 krk 0.67 13.00 22.00 8.65 20.99 21.78 24.92 15.38 58.15 skp 0.53 22.70 42.00 6.48 41.97 42.77 43.68 28.06 112.80 ylp 0.68 26.00 34.50 24.09 29.21 35.97 31.37 34.14 99.32 0 .8 3 0 .8 5 0 .6 3 0 .6 9 0 .9 1 0 .9 3 0 .9 5 0 .9 3 2 .3 2 2 .2 0 1 .6 4 1 .6 6 2 .8 2 2 .7 8 3 .0 1 2 .8 5 0.00 0.50 1.00 1.50 2.00 2.50 3.00 3.50 kmg kdc mdk mlg agm krk skp ylp d iv e rs it y i n d ic e s study sites simpson_1-d shannon_h srinivas and krishnamurthy /journal of tropical forestry and environment vol. 9, no. 02 (2019) 108-119 113 among eight study sites of the western ghats, the diversity indices showed that the highest richness was observed in mullayyanagiri with highest number of individuals. it is revealed that the highest simpson and shannon indices observed in sakaleshpur (d=0.95 and h=3.01),yellapur (d=0.93 and h=2.85), karkala (d=0.93 and h=2.78), agumbe (d=0.91 and h=2.82), kodachadri (d=0.84 and h=2.19), kemmannugundi (d=0.82 and h=2.32), mullayyanagiri (d=0.69 and h=1.65) and madikeri (d=0.63 and h=1.64) (figure 2). in the present study, a total of twelve species were encountered in all the study sites of central western ghats of karnataka. whereas, in previous studies sixteen species reported from western ghats of southern india (rao, 2012), twenty species occurred including new species l. udayanii (robi and udayan, 2014), nine species reported from terai region of west bengal (choudhury et al., 2014), twenty two species from eastern himalaya region, seventeen species from north eastern part and only six species from andaman and nicobar region of india (bhuniya et al., 2009). the data showed that, the present results with previous studies of other regions, the central western ghats of karnataka has more endemic species and present study reports that litsea ghatica is a rare species from karnataka region and particularly endemic to western ghats of karnataka. this species were observed from kodachadri and sakaleshpur regions. 3.2 influence of climatic factors on diversity and distribution of litsea (a) rainfall species diversity and distribution in the tropics varies from one area to other area because of some environmental, edaphic and topographic factors (rodrigues et al., 2018). rainfall is an important climatic factor for the growth, development and distribution of plants. in the present study, five years rainfall data from 2012 to 2016 has been used for the statistical analysis. according to the rainfall data, year 2013 had received highest average rainfall (259.18 mm) when compared with other years in all districts. it is followed by 2014 (237.40 mm), 2012 (200.60 mm), 2015 (190.61 mm) and 2016 (161.17 mm) (figure 3). among seven districts, udupi received highest rainfall (344.71 mm) when compared to other districts, while lowest rainfall recorded in hassan district (71.36 mm). overall rainfall data revealed that, udupi received highest average rainfall in the year 2013 as 404.38 mm and lowest average rainfall recorded in hassan in the year 2016 (48.36 mm). during 12 months, three months such as june, july and august month received high average rainfall in descending order. figure 3. year-wise average rainfall data of seven districts from 2012 to 2016. 0.00 50.00 100.00 150.00 200.00 250.00 300.00 0.00 50.00 100.00 150.00 200.00 250.00 300.00 350.00 400.00 450.00 2012 2013 2014 2015 2016 t o ta l a v e a rg e r a in fa ll a v e ra g e r a in fa ll years cmr dka hsn kdg smg udp uka total 114 average rainfall data showed that udupi district received highest rainfall followed by dakshina kannada, uttara kannada, shivamogga, kodagu, chikkamagaluru and haasan district receive lower rainfall because the only sakaleshpur region comes under the western ghats part of karnataka. the density of genus litsea is higher in mullayyanagiri region (48.40), followed by kemmannugundi (47.67), madikeri (41.66), kodachadri (39.95), agumbe (37.0), karkala (13.0), sakaleshpur (22.70), yellapur (26.0) (table. 2). the results indicate that litsea distribution and diversity rich in moderate rainfall regions of mullayyanagiri and kemmannugundi regions of chikkamagaluru district, madikeri of kodagu district and kodachadri, agumbe of shivamogga district. the average temperature of the study sites was 27ºc. the temperature in the study sites reflect on the flowering of genus litsea. in low temperature and high humidity conditions, flowering occurs on litsea trees and flowers blooms in the cold conditions. (b) nutrient contents in soil results of soil analysis of different study sites indicated kemmannugundi soil has more ph value (6.00) than madikeri (5.8), mullayyanagiri, yellapur (5.6) and least ph documented in agumbe soil (5.2). as per electrical conductivity analysis, kemmannugundi soil showed more ec (0.29), it is followed by sakaleshpur (0.26), karkala (0.23), mullayyanagiri (0.19), yellapur (0.15), agumbe (0.12), madikeri (0.1) and kodacahdri (0.07) (table. 3). in macro nutrients, high amount of phosphorus was found in two sites kemmannugundi and mullayyanagiri (12.9) and it followed by karkala (12.6) and lower amount of phosphorus was found in madikeri soil. high amount of potassium was recorded in agumbe (101.26 ppm) and least in kemmannugundi soil. second nutrient sulphur was also recorded high amount in agumbe soil (19.5 ppm) and it followed by kemmannugundi (16 ppm), mullayyanagiri and madikeri (14.25 ppm), sakaleshpur (13.9 ppm), yellapur (10 ppm), karkala (7.2 ppm) and kodachadri (0.3 ppm). available micro nutrients such as zinc, copper, manganese, iron and boron in different study sites sample showed much variability in their values. the high amount of zinc was recorded in karkala soil (2.84 ppm) and least in kodacahdri soil (2.04 ppm). the high amount of copper and boron was found in madikeri soil (0.95 ppm and 4.49 ppm respectively) and low in karkala soil (cu=0.14 ppm) and yellapur soil (b=0.03 ppm) respectively. the high amount of manganese and iron was found in yellapur soil, 73.26 ppm and 111.4 ppm, respectively (table. 3). table 3: nutrient characteristics of soil collected from study sites of western ghats, karnataka. soil ph ranged from 5.2 to 6.0 in the sampling sites which is a slightly acidic ph, in kemmannugundi the ph is near to neutral (6.0) due to salt washed from other areas getting deposited. the sample sites ph ec (mhos/ cm) p (kg/ac) k (ppm) s (ppm) zn (ppm) cu (ppm) mn (ppm) fe (ppm) b (ppm) kmd 6.0 0.29 12.9 54.35 16.00 2.54 0.17 52.40 49.28 2.11 mlg 5.6 0.19 12.9 84.44 14.25 2.46 0.26 3.26 69.28 0.55 kdc 5.3 0.07 11.5 58.15 0.30 2.04 0.71 16.14 58.71 2.66 mdk 5.8 0.10 5.3 88.80 14.25 2.49 0.95 48.48 82.14 4.49 agm 5.2 0.12 7.2 101.26 19.50 2.66 0.17 8.47 78.52 3.95 krk 5.3 0.23 12.6 60.30 7.20 2.84 0.14 26.20 64.15 3.72 skp 5.5 0.26 10.6 72.40 13.90 2.75 0.81 32.30 69.80 4.26 ylp 5.6 0.15 7.2 75.53 10.00 2.26 0.35 73.26 111.4 0.03 srinivas and krishnamurthy /journal of tropical forestry and environment vol. 9, no. 02 (2019) 108-119 115 electrical conductivity ranged from 0.07-0.29, micro and macro nutrients are slightly varied from different study sites. soil analysis data indicates that litsea abundance is higher in 5.6 to 6.0 ph regions (kemmannugundi, madikeri, mullayyanagiri). the macro and micro nutrients of the soil in the study area reflects the distribution of the genus, according to edaphic data, litsea tree prefers high iron content in soil. soil ph, organic matter clearly reflects on the diversity and distribution of tress. the litsea tree species are found distributed in valley areas of western ghats. these valleys are rich in all micro and macro nutrients, density of tree species are higher where nutrients are higher in soil. (c) topographic factors topographic factors are more important in distribution of lauraceae species including genus litsea. the study site mullayyanagiri is the highest elevation region (1,619 m) in south india followed by kemmannugundi (1,536 m), kodachadri (1,199 m), madikeri (1143 m) and least in karkala (639 m) (table. 4). in the present study, the diversity data correlated with altitudinal data. the species showed higher rate of distribution in elevated altitudinal regions when compare to lower altitudes. the density of litsea trees is higher in mullayyanagiri, kemmannugundi, kodachadri and madikeri when compare to other study sites. it is evident from the results; species prefers high altitudinal habitats from sea level it distributed around 601 m to 1,619 m elevation. there is a gradual increasing in tendency of the species with increasing elevation when compare with lower elevated regions. this is because of the higher atmospheric moisture and lower temperature in high altitudinal habitats. most of the laural members distributed in higher altitudinal regions along with genus litsea. the abundance, frequency ratio indicated that the litsea showed clumped or contagious distribution pattern and seedlings are adopted to grow close to the mother trees. in previous studies confirmed that the topographic factors are important in woody tree species distribution when compare to other environmental parameters. species distribution and forest compositions were strongly associated to topographic parameters reported in mountain forests of china (zhang et al., 2016). this study was also reported that the elevation is the important factor positively affects the tree species distribution, in present study the tree species litsea also showed more sensitive and positive association with the elevation factor. table 4: topographic data of different sampling sites of litsea in western ghats, karnataka. sampling sites district latitude longitude altitude (m) kemmannugundi chikkamagaluru 13°32'25" n 75°45'55" e 1,536 mullayyanagiri chikkamagaluru 13°23'25" n 75°42'59" e 1,619 kodachadri shivamogga 13°51'32" n 74°52'20" e 1,199 agumbe shivamogga 13°31'56" n 75°05'38" e 664 chakra shivamogga 13°48'52" n 74°57'55" e 601 bhagamandala kodagu 12°22'84" n 75°31'32" e 952 madikeri kodagu 12°25'69" n 75°44'61" e 1,143 bhisle ghat hassan 12°42'42" n 75°41'17" e 752 satodi falls, yellapur uttara kannada 14°59'58" n 74°38'87" e 734 charmadi ghat dakshina kannada 13°06'44" n 75°29'37" e 808 karkala udupi 13°16'11" n 75°08'09" e 639 116 (d) species distribution modelling figure 4. receiver operating characteristics for litsea. the graph obtained by software was receiver operating characteristic curve for the similar data. this graph defines the specificity using predicted area than true commission. it indicates the maximum achievable area under cover (auc) is less than one (auc=0.999) (figure 4). the auc value of training data almost nearer to one, hence this species distribution model consider as good sdm model and this implies litsea species has 99 per cent chance of complete distribution in a place of western ghats. present study shows distribution of litsea similar to the species distribution model results in central western ghats of karnataka. the distribution of the trees was higher in high sdm value regions and these areas appear darken red colour, medium species areas appear yellow colour and in blue colour regions there is no reports of litsea distribution (figure 5). distribution showed in kemmannugundi, mullayyanagiri, kodachadri, agumbe, madikeri areas of central western ghats are higher sdm values and appears in dark red region. sakaleshpur, charmadi ghat, yellapur, kavaledurga, hosanagara, karkala regions showed medium distribution of litsea and these areas having medium sdm values and appears in yellow coloured regions in the distribution model. litsea trees distribution predicted across the western ghats of south india. in maharashtra region of western ghats having deciduous forests, mahabaleshwar, satara regions showed medium species distribution pattern. castle rock and kulem regions of goa is a rich biodiversity area and covers mountains and valleys showed higher distribution of litsea. tamil nadu region of western ghats includes evergreen forests of kalakkad mundanthurai tiger reserve (kmtr) of tirunelveli and mudumalai reserve forests around ooty, coimbatore and nilgiris region having higher number of litsea species which showed rich distribution of species. kerala parts western ghat regions show rich biodiversity when compare to other regions. highest number of litsea species will be found in kerala by previous records including more number of endemic species. these species are distributed in periar national park region, kannur, idukki, srinivas and krishnamurthy /journal of tropical forestry and environment vol. 9, no. 02 (2019) 108-119 117 thekkady, munnar and wayanad regions. from the distribution model analysis, these western ghat areas are higher sdm values and most of litsea species distributed in this region. figure 5. species distribution model (sdm) of litsea in western ghats of india. 4. conclusion in present study a total of twelve species (litsea bourdillonii, l. coriacea, l. deccanensis, l. floribunda, l. ghatica, l. glabrata, l. glutinosa, l. laevigata, l. mysorensis, l. oleoides, l. stocksii and l. wightiana) were found and identified from our study area. the diversity and ecological data indicated that it is varied from one region to another region by the influence of external factors. the environmental factors such as rainfall, temperature and edaphic factors such as soil and higher elevation influence the distribution of litsea. the analysed rain fall data indicate that trees distribution and diversity is rich in moderate rain fall regions of mullayyanagiri and kemmannugundi regions of chikkamagaluru district, madikeri of kodagu district and kodachadri, agumbe of shivamogga district. the temperature in the study sites reflects on flowering of the genus. in low temperature and high humidity condition the flowering event occurs on the trees. soil data indicates that litsea diversity and distribution is higher in 5.6 to 6.0 ph regions (kemmannugundi, madikeri, mullayyanagiri). the macro and micro nutrients of the soil in the study area reflects the distribution of the genus. the tree species are found distributed in valley areas of western ghats. these valleys are rich in all micro and macro nutrients. tree density is higher where nutrients are higher in soil. in present study, correlation of the diversity data with altitudinal data, the species showed higher distribution in elevated altitudinal regions when compared with lower altitudes. there is a gradual increase in tendency of the species with increasing elevation when compared with lower elevated regions. this is because of the higher atmospheric moisture and lower temperature in high altitudinal habitats. most of the 118 laural members distributed in higher altitudinal regions along with genus litsea. this study was also reported that the elevation is the important factor positively affects the tree species distribution. acknowledgments authors are thankful to department of science and technology (dst), new delhi, for providing inspire fellowship (if140097) to srinivas s.g, which provided financial support for the study. the authors also acknowledges to kuvempu university and applied botany department for providing infrastructural and administrative support. specially authors acknowledge the karnataka forest department for according permission to enter the forests. references bhuniya, t. and mukherjee, s.k., 2012. status of litsea lam. (lauraceae) in andaman and nicobar islands, india. systematics of flowering plants, 2012:145-148. bhuniya, t., singh, p. and mukherjee, s.k., 2009. distribution of the genus litsea lam. (lauraceae) in india with special reference to rare and endemic species. phytotaxonomy, 9:116-121. bhuniya, t., singh, p. and mukherjee, s.k., 2010. an account of the species of litsea lam. (lauraceae) endemic to india. bangladesh journal of plant taxon, 17:183-191. brilliant, r., varghese, v.m., paul, j. and pradeep kumar, a.p., 2012. vegetation analysis of montane forest of western ghats with special emphasis on ret species. international journal of biodiversity and conservation, 4:652-664. chiang, y.c., shih, h.c., huang, m.c., ju, l.p. and hung, k.h., 2012. characterization of microsatellite loci from litsea hypophaea (lauraceae), a tree endemic to taiwan. american journal of botany, 2012:251-254. choudhury, d., biswas, r., mandal, p. and das, a.p., 2014. diversity of litsea lamarck. (lauraceae) in terai and duars regions of west bengal, india. pleione, 8:68-78. ganesan, r., 2011. litsea kakkachensis (lauraceae)-a new species from agasthyamalai, western ghats, india. rheedea, 21: 43-146. huang, p., li, j. li, x. and van der werff, h., 2008. litsea. flora of china, 7:118-141. kumar, a., marcot, b.g. and saxena, a., 2006. tree species diversity and distribution patterns in tropical forests of garo hills. current science, 91:1370-1381. mishra, c.k. and naidu, g.r., 2013. conservation of litsea deccanensis: an ntfp under local extirpation. indian forester, 139:769-772. ngernsaengsaruay, c., middleton, d.j. and chayamarit, k., 2011. a revision of the genus litsea lam. (lauraceae) in thailand. thai forest bulletin (botany), 39:40-119. pendry, c.a., watson, m.f., akiyama, s., ikeda, h., rajbhandari, k.r. and shrestha, k.k., 2011. lauraceae. flora of nepal, 3:21-48. ramesh, b.r. and pascal, j.p., 1997. atlas of the endemics of the western ghats (india): distribution of tree species in the evergreen and semi evergreen forests. institute of francais de pondicherry, publication du department d ecologie, 38:403. rao, r.r., 2012. floristic diversity in western ghats: documentation, conservation and bio prospection-a priority agenda for action. http://wgbis.ces.iisc.e639rnet.in/biodiversity/sahyadri_enews/newsle tter/ issue. robi, a.j., george, s. and thushar, k.v., 2015. litsea udayanii (lauraceae): a new species from the southern western ghats, india. phytotaxa, 222:44-50. robi, a.j. and udayan, p.s., 2014. a taxonomic revision of the family lauraceae from south india. ph.d. thesis, kannur university, kerala. srinivas and krishnamurthy /journal of tropical forestry and environment vol. 9, no. 02 (2019) 108-119 119 rodrigues, p., schaefer, r., silva, o., junior, f., santos, m. and neri, v., 2018. the influence of soil on vegetation structure and plant diversity in different tropical savannic and forest habitats. journal of plant ecology, 11:226-236. saldanha, c.j., 1984. flora of karnataka. vol. 1, oxford and ibh publishing ltd., new delhi. upadhaya, k., pandey, h.n., law, p.s. and tripathi, r.s., 2003. tree diversity in sacred grooves of the jaintia hills in meghalaya, northeast india. biodiversity and conservations, 12:583-597. zhang, c., li, x., chen, l., xie, g., liu, c. and pei, s., 2016. effects of topographical and edaphic factors on tree community structure and diversity of subtropical mountain forests in the lower lancang river basin. forests, 7:1-17. young /journal of tropical forestry and environment vol. 9, no. 02 (2019) 1-11 __________________________________________ *correspondence: sansfica@et.cmb.ac.lk tel: 0719099122 issn 2235-9370 print / issn 2235-9362 online © university of sri jayewardenepura 1 feature article grain size and chemical composition of sediments to determine the governing geochemical processes in fluvial environments sansfica m. young department of environmental technology, faculty of technology, university of colombo, colombo 03, sri lanka abstract the environmental impact on the river system and the bay or a tidal flat area is of significance since these environments act as sinks of pollutants. the river system gradually gathers the material that flows along the river and settles it at the downstream area. the geochemistry of sediments of the rivers and the bay or tidal area are signatures of the mass transfer process that occur in fluvial environments. thus, the processes such as provenance, maturity of sediments, weathering, climatic implications, sedimentary processes, heavy mineral concentrations, sorting and mixing effect, grain size variation, transport and downstream accumulation and effect of tributaries can be determined using geochemistry. the major oxides and trace element concentration of the sediments of the river and the bay or tidal area is thus very important to determine the fluvial processes. comparison of two different fluvial environments with different climatic conditions and geology where one consists of the river with a bay in sri lanka and the other consisting of a river with a tidal flat in japan is thus conceded. the environmental assessment using elements of sediments in such environments have been effective due to the possibility of being able to identify the fluvial processes that are affected by the river and bay or tidal sediments in two different systems. keywords: fluvial environment, geochemistry, sediment, major oxides, trace elements 1. introduction stream sediments comprise of the compounds of the lithologies present in their drainage basins, and therefore, facilitate in a mechanism for mapping regional geochemical characteristics of their source terranes (ottesen and theobald, 1994). however, the compositions of clastic sediments are different from that of their source rocks due to the effect of a combination of numerous interacting factors that function between source and sediment. the factors include hydrodynamic sorting, weathering, heavy alluvial storage, mineral concentration and many others johnsson (1993). the significance of kuma river and yatsushiro bay in japan is that, they are situated in the island of kyushu, which is of japanese island arc, and is the largest river subjected to asian monsoons, flooding occur with high rain fall while a large population depend on the river for their living. the first ever dam removal occurred in arase, japan which was situated in the middle region of the kuma river. the river mouth is at yatsushiro, which comprises of a tidal flat subjected to almost 1 m tidal variation. on the other hand, the mahaweli river rises on the hatton plateau of the wet zone, flows north through the intermediate zone, flows past polonnaruwa to its mouth in koddiyar bay, 11 km south of trincomalee in the dry zone (figure 1). mahaweli river flows throughout the year, providing water for agriculture in the eastern dry zone. the mahaweli river mainly flows through the highland complex (figure 1). doi: https://doi.org/10.31357/jtfe.v9i2.4463 2 it was thus important to select these locations to identify the processes in (a) mahaweli river and trincomalee bay system and (b) kuma river and yatsushiro bay system to study the geochemical impacts as a whole system of river, estuarine and marine environments in two different environmental, geological and climatological aspects. figure 1. (a) the geology of the mahaweli river and trincomalee bay (b) kuma river and the sampling locations in kumamoto prefecture, kyushu island, japan. the kuma river in japan consisted of a dam which was partially opened during the time of sampling which was located~19.9 km from the mouth of the 115 km long kuma river (figure 1). the drainage area of the kuma river is 1,880 km2, and it is considered to be one of the three most rapid rivers of japan. the kuma river falls to the yatsushiro bay a semi-closed estuary opening to the east china sea. the kuma river and the yathsushiro bay area is subjected to all four climatic conditions. the geology of kuma river and the yathsushiro bay area is highly complex. the kuma river flows through the chichibu terrane, the hisatu volcanics, the cretaceous-paleogene sedimentary rocks, the shimanto terrane, and associated alluvial deposits (figure 1). yatsushiro bay is located in the chichibu terrane (figure 2). the yatsushiro area is within the inner and outer zones of the kyushu cretaceous system (sakai et al., 1992). the sedimentary basins of kyushu belong to the cretaceous and tertiary periods. the yatsushiro region and the kuma river catchment intersect the early cretaceous shallowmarine and turbidite basins and the late cretaceous non-marine, shallow-marine, and turbidite basins in the ryoke terrane (sakai et al., 1992). the kawabe river joins the kuma river after it flows through the shimanto terrane and the chichibu terrane (figure 1). kyushu has active island arc type volcanoes, active faults, and significant crustal movement (ogawa et al., 1992). thus, the objectives of investigating the mahaweli river sediments would be to identify the provenance and the processes controlling these systems for future development (construction), natural hazards and environmental issues. assessment of the mahaweli river sediments would make known the young /journal of tropical forestry and environment vol. 9, no. 02 (2019) 1-11 3 geochemical characteristics of sediments in the mahaweli river, in order to understand the intensity of weathering and erosion and to identify the provenance signatures. the intention of investigating the trincomalee bay surface sediments is to establish the geochemical characteristics of surface sediments in the three sectors of trincomalee bay in order to determine their provenance, evaluate roles of circulation and oceanic influence, within the bay in modifying sediment compositions and assess present environmental conditions. the objective of studying the kuma river and yatsushiro bay is to identify the effect of kuma river sediments on yatsushiro bay after opening of the arase dam gates 2010 april, and document the geoenvironmental conditions of yatsushiro bay and the kuma river. 2. geochemical implications of fluvial systems in environmental studies the sampling procedure and sampling locations are very important. it is generally accepted that systematic sampling gives a better representation regarding the samples collected for geochemical interpretations. however, in most of the cases, especially in fluvial, bay and tidal environments sampling is difficult. the sampling deals with deep and shallow water bodies, deep and shallow mud flats, steep banks, eroded land forms, shrubs or forest cover and therefore, the sampling locations has limited or no access for sampling. therefore, systematic sampling is challenging in such studies. thus, leading to random sampling methods from where easy access is available for sampling. sample preparation is critical since the samples are most of the time collected as wet samples since they are submerged under water. due to storage of samples that are wet, oxidation reactions could take place. however, in most cases the total elemental concentrations of the soil or sediment is not subjected to change. transporting and storing the samples in sealed and cool conditions is important. if not microbial reactions could take place and change the oxidized or reduced conditions leading to change in fractions of functional groups. xrf analysis is a widely used very accurate method to detect the major oxides and trace element concentrations of bulk soil and sediment samples. the elemental concentrations and its variation is widely used to determine the source composition, climatic variation, heavy mineral signatures, effect of tributaries, natural activities and mainly pollution interpretations due to anthropogenic activities. the elemental concentration of soil and sediment used to determine its composition is usually normalised with upper continental crust (ucc, taylor and mclennan, 1985) for soils and with post archean australian shale (paas) for sediments. the variation is interpreted using enrichments or depletions of elemental concentrations on an average basis. this method of interpretation will give an idea about the elements that show different signatures based on environmental concerns (as, pb, zn, cu, ni, cr, young and ishiga, 2014a, b), provenance indicators (th, sc, zr, cr, v, y, ni, roser and korsch, 1999), heavy mineral signatures (zr, th, nb, y, sr, ti, roser et al., 2000), weathering activities (na, k, al, si, mg, fe, price and velbel, 2003), petrogenic signatures (p) and progressive weathering of calcareous detritus (ca, sr, young et al., 2013). further, statistical methods involving cluster analysis, principal component analysis (pca) and factor analysis (woods et al., 2013) is used to interpret the elemental variation for natural as well as anthropogenic activities (young et al., 2014; young et al., 2013). these principles could group or cluster the elements that relate to one or a few geochemical process so that it could be understood as to how it took place and the consequences of it to the environment. further, there are number of indexes developed by many researchers. such as; geo-accumulation index, as for the guidelines used by nysdec (new york state department of environmental conservation) values of lower effect level (lel) and severe effect level (sel), isqg (interim sediment 4 quality guidelines) and probable effect level (pel) is generally used to evaluate sediments (young et al., 2014). there are single indices which are indicators used to calculate contamination of only one metal, which include contamination factor, ecological risk factor, enrichment factor and index of geoaccumulation (qingjie et al., 2008). weathering can be determined using various methods. however, most of the commonly used weathering indices such as cia (nesbitt and young, 1982; price and velbel, 2003), pia (fedo et al., 1995), ciw (harnois, 1988), and wip (ohta and arai, 2007) include cao in the calculations. each of the index is used for different purposes where the applications are based mainly for assessment of pollution and weathering. the intensity of pollution is mainly in relation with heavy metals and are evaluated based on sediments of different environments such as marine, brackish, lake and fluvial (ishiga et al., 2012; young et al., 2014; young and ishiga, 2014a,b). the enrichment factor (ef) is another index calculated using the formula given in zhang et al., (2007) where (me/fe)sample is divided by (me/fe)background (me, metal) and used where the values of 0.51.5 suggest that the trace metals concerned may be derived entirely from crustal materials or natural weathering processes (zhang and liu, 2002). values greater than 1.5 suggest that a significant portion of the trace metal has been delivered from non-natural (anthropogenic) sources (zhang et al., 2007). in addition, the loss on ignition (loi) is also commonly used to discuss the loss on organic matter content upon burning in a muffle furnace to 105o c for two hours which is an indication of the organic matter content on soils and sediments. the higher the organic matter content not only the nutrient content will be high, the heavy metal content also will increase since the absorption, adsorption and coagulation takes place very easily into organic matter. the downstream variation of sediments can be related with the accumulation and variation of the elemental concentrations. along a stream the sediments are subjected to mechanical, chemical and physical weathering. the slow and fast flow of water, the water and sediments entering the main stream in confluences, the climatic variation, the anthropogenic inputs and erosion are factors that cause to change the elemental variation of sediments along the stream. heavy minerals are a major component in sediments and soil since they are products of weathering process. fluvial sediments of a river are resulted from weathering of a variety of parent rocks that are within the river basin. the composition of heavy minerals are mainly controlled by several environmental processes, including selective physical breakdown, hydrodynamic sorting, and chemical weathering during transport and deposition. the geomorphologic evolution and the fingerprint of an area’s geological setting can be provided by using tracing studies for river sediments (roser and korsch, 1999). the heavy mineral signatures are determined mainly by the elements zr, ti, cr, v, y, ni, th and sc (roser et al., 2000). heavy minerals do not travel very far unless with heavy currents since the soils and sediment grains are heavy. however, mineral such as mica will travel very far and mainly deposit downstream and close to and within the river mouth area. due to the effect of currents, high energy areas are formed and the sediments consisting with heavy minerals are deposited in these places with high energy. therefore, the heavy minerals that are brought downstream along the river are deposited in patches consisting of heavy energy within the bay area. the entire river transporting sediments will cut across one or many climatic zones where the sediments are subjected to different climatic conditions. thereby the sediments undergo chemical changes due to the different chemical environments. 3. grain size variation of river systems in sri lanka and japan different size factions used for grain size analysis and for chemical composition differ based on the purpose of the study and the river morphological features. thus, the grain size analysis of the kuma river and yatsushiro bay sediments were sieve separated into fine (0.075-0.25 mm) and medium (0.25young /journal of tropical forestry and environment vol. 9, no. 02 (2019) 1-11 5 0.85 mm) size fractions (n=14). the samples were oven dried and treated with 30 % h2o2 for at least 24 h prior to measurement. grain size analysis for six size fractions was carried out at tokyo university of science for the surface and bottom sediments using a sald 3,000 grain size analyser. calculations of grain size and sorting were made following folk and ward (1957). the mahaweli river sediment samples were first hand-sieved to remove the small amount of material>2,000 µm. the<2,000 µm fraction was then split to provide a sample for bulk sediment analysis (<2,000 µm). a second split was then sieved to separate<180 µm and 180-2,000 µm fractions for fractional analysis. the grain size variation along a river is a major indication of the geochemical processes that affect and control the river sediment. in general, sediment grain size in rivers decreases downstream (parker, 1991; surian, 2002) but this is not the case for the mahaweli river. the main channel sediments were coarse to medium sand with lesser clay fractions, except for eleven samples in the middle reaches that contained more than 20% clay (figure 2). the gravel content of most samples was low (<20%), except for one sample in the middle reaches and two in the lower reaches. there is little improvement in sorting along most of the main channel, and median grain size is also highly variable. this is probably due to the number of tributaries entering the main channel, even in the middle reaches. the sediments only become well sorted in the lowermost reaches of the river, where tributaries are fewer. mean grain size of the trincomalee bay sediments ranged from -0.13 to 4.60 ɸ equivalent to very coarse sand to coarse silt. sediments are also generally well sorted. figure 2. variation in stream sediment size fractions along the mahaweli river. the kuma river sediment sampling was carried out for surface and bottom sediment to determine if there is a difference in grain size and its chemical variation due to removal of the arase dam. the median grain size (md ф) of the surface sediments (-0.57 and 3.27 ф) is poorly sorted and has a wider range while the bottom sediments (-0.93 and 2.93 ф) are moderately sorted and is within a shorter range. the surface and bottom sediments of the kuma river and the yatsushiro bay mainly consist of very coarse sand to very fine sand (figure 3). thus, there is a clear difference in the surface and bottom sediments. 6 figure 3. grain size variation of the (a) fine (0.25-0.005 mm) and (b) medium (0.25-2 mm) fractions of surface and bottom sediments of kuma river and yathsushiro bay. when consider the arase dam area median grain sizes (ф) for the bottom sediment are low (-0.93, -0.83) however is high in the dam surface sediments (2.63, 2.53). this implies that in the dam sediments fine fraction is very less and with higher coarse sand grain percentages at the dams. it is very clearly seen that above the arase dam (upstream) median grain size of the river sediments is low in both surface and bottom sediments. the surface sediment grain size of the river is higher than that of the bottom sediments. the sorting is low (average, 1.0) in the bottom sediments but high (average, 1.1) in the surface sediments. most of the bed load sediments were transported downstream and also point bars were formed in the banks of the river. the grain size analysis of the arase dam and the kuma river sediment clearly shows that, the channel morphology and the hydraulics is influenced by the grain size of river bed sediments (surian, 2002). 4. chemical variation of river systems in sri lanka and japan the xrf method of analysing the elemental concentrations of bulk sediments, rock and soils is a powerful, well-established and a widespread practice. therefore, to determine the elemental concentrations of the sediments for the mahaweli river, trincomalee bay and kuma river, yatsushiro bay systems, the xrf method was used. the chemical composition of the sediments was determined by xrf analysis to carry out the interpretations. approximately 50 g of each sample were oven dried at 160° c for 48 hrs before crushing in a tungsten carbide ring mill. portions (7-10 g) of the crushed materials were transferred to glass vials and dried at 110° c for 24 h prior to determination of loss on ignition (loi). the loi values were calculated from the net weight loss after ignition in a muffle furnace at 1020° c for more than 2 h. abundances of 23 major elements and trace elements (as, pb, zn, cu, ni, cr, v, sr, y, nb, zr, th, sc, ts, f, br, i, cl, ti, fe, mn, ca, and p) were determined from pressed powder briquettes, following ogasawara (1987) using a rigaku rix-2,000 xrf spectrometer. analytical methods, instrumental conditions, and calibration followed those described by ogasawara (1987). the pressed powder analysis followed ogasawara (1987), using conventional peak over background (ip/ib) method, with calibration against recommended or preferred values for seven geological survey japan (gsj) rock standards. arsenic values were also corrected for pb peak overlap. average 2-sigma coefficients of variation for the three elements range from 3.5-6.7% relative at concentrations of >5 ppm. this was confirmed by repeat analysis (n=5) of seven samples from this study, yielding similar results. to compare with typical upper crustal values and determine the differences between the sample types the average values in the sediments of the mahaweli river, rocks and soils of the catchment area were normalised against average post archean australian shale (paas; taylor and mclennan, 1985). the mahaweli river sediments are highly enriched in cao, v and zr, and moderately enriched in tio2, cr, sr, nb, th and sc while cu and ni are depleted relative to paas (figure 4a). most elements in the young /journal of tropical forestry and environment vol. 9, no. 02 (2019) 1-11 7 soils are depleted (e.g. zn, cu, ni, y and nb). the rocks are also mostly depleted relative to paas, especially for tio2, cu, ni, nb, zr and th (young et al., 2013). the sediments are slightly enriched in p2o5 relative to the soils and rocks, possibly due to concentration of accessory phases such as apatite and monazite (nagarajan et al., 2007). figure 4. (a) paas-normalized averages for the sediments, soils and basement rocks of the mahaweli river, (b) paas-normalized averages for the bottom kuma river (bkr) bottom yatsushiro bay (byb), surface kuma river (skr) and surface yatsushiro bay (syb) sediments. taylor and mclennan (1985). all four sampling types for bottom kuma river (bkr) bottom yatsushiro bay (byb), surface kuma river (skr) and surface yatsushiro bay (syb) sediments show a similar variation for all the elements. thus, except for arsenic all other elements ti, fe, mn, ca, p, pb, cu, ni, cr, v, sr, y, nb, zr and th are depleted in relation to paas (figure 4b). acquiring the similar average composition in all four types of samples relation to paas indicated that the sediments are not undergoing major geochemical changes with the different fluvial environments. however, when consider each element variation along the river there are differences in the surface as well as in the bottom sediments and also before and after the arase dam (young and ishiga, 2014b). 5. provenance signatures of river systems in sri lanka and japan possibility of provenance, sorting or accumulation of heavy minerals can be evaluated using th/sc and zr/sc where the ratio serves as a proxy for identifying heavy mineral concentrations, because it is highly sensitive to accumulation of zircon (mclennan et al., 1993). in the mahaweli river the sediments are highly scattered and shows that they are slightly enriched in zircon, the basement rocks show a range from mafic through to felsic compositions, as do the soils (figure 5a). the basement samples plotting at higher ratios include quartzites and quartzofeldspathic gneisses. the trincomalee bay sediments indicates that the bulk of the clastic sediment in trincomalee bay is derived from the mahaweli river. the higher zr/sc ratios in koddiyar bay near the mahaweli delta, and lowest values in the most distal setting of the inner harbour suggest that heavy minerals have played an important role in elemental distributions within trincomalee bay (figure 5a). 8 figure 5. zr/sc–th/sc (mclennan et al., 1993) for the (a) mahaweli river and trincomalee bay (b) kuma river and (c) yatsushiro bay (mc-main chanel, tb-tributary, lm-lower mahaweli). the surface and the bottom sediments of the kuma river have the same composition (figure 5b). the provenance of yatsushiro bay was examined using sediment elementary data of 2006, 2012 and 2013 (young and ishiga, 2014a). the yatsushiro bay sediment data shows that there is a change in composition since 2006-2013 (figure 5c). the yatsushiro bay sediment composition with time have moved towards the composition of paas from 2006-2012. after 2012 the composition moves toward the line on rhyolite to dacite up to 2013 with not much change (figure 5c). thus, in the yatsushiro bay the composition changes to the background detrital composition (young and ishiga, 2014a). 6. environmental conditions of river systems in sri lanka and japan the elements y, th, zr, nb, ti and sc are good indicators of heavy minerals. owing to high durability, minerals tend to remain in sediments during transport over long distances. tourmaline, zircon, and rutile are associated with significant enrichments of th, zr and nb, and suggest a granitic source or recycled detritus (young et al., 2013). disseminations of th, zr and nb in the stream sediments are usually controlled by heavy minerals including garnet, monazite, zircon and titanite, with the lesser changeability being produced by homogenization of the detrital bedload during transport. the scattering of zr to higher values is comparatively rational, this suggests that the zircon concentration is the main reason for enrichment (young et al., 2013). it is suggested that the higher scattering of y and nb is controlled by the abundance of multiple heavy minerals. the sediments of the tributaries also show high values for th, zr and nb in the <180 µm fraction, suggesting that preferential concentration of heavy minerals in the fine fraction is not a function of transport distance (young et al., 2013). spikes at the entries of tributaries are likely to be caused by heavy minerals, and there is no significant change seen with climatic zones (young et al., 2013). the loi values of the soils are 0.61-12.86 wt% and sediments range between 0.31-16.18 wt%, indicating considerable amounts of organic matter in the sediments. however, calcium contents are naturally high in the carbonate rocks in the mahaweli river catchment. since the ca contents are high, for weathering interpretations in the mahaweli river, the cia, pia, ciw, and wip indexes cannot be used. nevertheless, the ratios of immobile to mobile elements (k2o/na2o and al2o3/(k2o+na2o)) can be used to determine the degree of weathering and morbidity (nesbitt and young, 1982; gallet et al., 1996) and was used for the mahaweli river to determine the weathering across the three climatic zones. a clear young /journal of tropical forestry and environment vol. 9, no. 02 (2019) 1-11 9 change across the climatic zones for the al2o3/(k2o+na2o) ratios (young et al., 2013). due to the rich al content in the wet zone sediments, it can be implied that considerable amount of clay is derived from feldspars. it also shows that intense weathering occurs in the elevated areas of the upper catchment and decreases downstream (young et al., 2013). the enrichment factor (ef) is commonly used to detect the anthropogenic signatures. for the mahaweli river sediments all other elements are strongly depleted, with ef<1 except for cr throughout the river and pb at a few sites in the dry zone and may related to the local lithology. thus, mahaweli river sediments represent background values, and there is no threat of anthropogenic contamination (sutherland, 2000; zhang and liu, 2002). the ef of the sediments of the kuma river is less than 1.5 for all elements (young and ishiga, 2014b) indicating that there is no anthropogenic contamination as for zhang et al., 2007 and the yathsushiro bay sediments ef are similar to the kuma river sediments (young and ishiga, 2014b). the kuma river sediments consists of low loi values (2.32-2.99) indicating less organic matter in the sediments. however, location ya-1 has a loi of 18.10 which is very high and the southern area of the uto peninsula area consists of a high value of loi (8.27-11.02) and indicates high organic matter content in the sediments (young and ishiga, 2014a). 7. conclusions when consider both river systems, the mass transfer process and their potential impacts on the terrestrial and marine environments could be related to provenance, maturity of sediments, weathering, climatic implications, sedimentary processes, heavy minerals concentration, sorting and mixing effect, grain size, transport and downstream accumulation, effect of tributaries and sediment recycling. the main processes involved in the mahaweli river and trincomalee bay sediment environments are; transport, sorting, erosion, weathering, deposition, heavy minerals, tributary input and climate. the kuma river and yatsushiro bay involves erosion, deposition, sorting and transport. acknowledgment author acknowledge the japanese government for financial assistance to carry out our study, the staff of shimane university for the unending support for analysis and guidance. references fedo, c.m., nesbitt, h.w. and young, g.m., 1995. unraveling the effects of potassium metasomatism in sedimentary rocks and paleosols, with implications for paleo weathering conditions and provenance. geology, 23: 921-924. folk, r.l. and ward, w.c., 1957. brazos river bar: a study of significance of grain size parameters. journal of sedimentary petrology, 27:3-26. gallet, s., jahn, b.m. and torii, m., 1996. geochemical characterization of the luochuan loess-paleosol sequence, china and paleoclimatic implications. chemical geology, 133:67-88. harnois, l., 1988. the ciw index: a new chemical index of weathering. sedimentary geology, 55:319322. ishiga, h., sakaya, m., sakamoto, m., hasegawa, m., young, s.m. and diallo, i.m., 2012. geochemical evaluation of the effect on a tidal flat environment by fluvial flooding in the miyagawwa river mouth estuary, ise area, mie prefecture japan. geoscience reports of shimane university, 31:5969. johnsson, m.j., 1993. the system controlling the composition of clastic sediments. geological society of america special paper, 284:1-19. 10 mclennan, s.m., hemming, s., mcdaniel, d.k. and hanson, g.n., 1993. geochemical approaches to sedimentation, provenance and tectonics. the geological society of america. special paper, 284:21-40. nagarajan, r., madhavaraju, j., nagendra, r., armstrong-altrin, j.s. and moutte, j., 2007. geochemistry of neoproterozoic shales of the rabanpalli formation, bhima basin, northern karnataka, southern india: implications for provenance and paleoredox conditions. revista mexicana de ciencias geologicas, 24:150-160. nesbitt, h.w. and young, g.m., 1982. early proterozoic climates and plate motions inferred from major element chemistry of lutites. nature, 299:715-717. nysdec (new york state department of environmental conservation) 1999. technical guidance for screening contaminated sediments (45). albany, ny:nysdec, division of fish, wildlife and marine resources. ogasawara, m., 1987. trace element analysis of rock samples by x-ray fluorescence spectrometry, using rh anode tube. bulletin of geological survey of japan, 38: 57-68. ogawa, y., nishiyama, t., obata, m., nishi, t., miyazaki, k., ikeda, t., yoshimura, y. and nagakawa, k., 1992. continental margin tectonics in kyushu, southwest japan-mesozoic paired metamorphic belts and accretionary complexes. paleozoic and mesozoic terranes: basement of the japanese island arcs. 29th igc field trip guide book vol.1. nagoya university, 1:261-315. ohta, t. and arai, h., 2007. statistical empirical index of chemical weathering in igneous rocks: a new tool for evaluating the degree of weathering. chemical geology, 240:280-297. ottesen, r.t. and theobald, p.k., 1994. stream sediments in mineral exploration. in hale m. and plant j. a. (eds). handbook of exploration geochemistry, elsevier, amsterdam, 6:147-84. parker, g., 1991. downstream variation of grain size in gravel rivers: abrasion versus selective sorting. fluvial hydraulics of mountain regions, springer, berlin, heidelberg, 37:345-360. qingjie, g., jun, d., yunchuan, x., qingfei, w. and liqiang, y., 2008. calculating pollution indices by heavy metals in ecological geochemistry assessment and a case study in parks of beijing, journal of china university of geosciences, 19:230-241. roser, b.p., ishiga, h. and lee, h.k., 2000. geochemistry and provenance of cretaceous sediments from the euisong block, gyeongsang basin, korea, mem. geol. soc. japan, 57, 155-170. roser, b.p. and korsch, r.j., 1999. geochemical characterization, evolution and source of a mesozoic accretionary wedge: the torlesse terrane, new zealand, geol. mag. cambridge university press 136:493-512. sakai, t., okada, h. and aihara, a., 1992. cretaceous and tertiary active margin sedimentation: transect of kyushu. paleozoic and mesozoic terranes: basement of the japanese island arcs. 29th igc field trip guide book vol.1. nagoya university, 1:317-354. surian, n., 2002. downstream variation in grain size along an alpine river: analysis of controls and processes. geomorphology, 43:137-149. sutherland, r.a., 2000. a comparison of geochemical information obtained from two fluvial bed sediment fractions. environmental geology, 39:330-341. taylor, s.r. and mclennan, s.m., 1985. the continental crust: its composition and evolution. oxford: blackwell scientific. 312. woods, a.m., lloyd, j.m., zong, y. and brodie, c.r., 2012. spatial mapping of pearl river estuary surface sediment geochemistry: influence of data analysis on environmental interpretation, estuarine, coastal and shelf science, 115, 218-233. young, s.m., pitawala, a. and ishiga, h., 2013. geochemical characteristics of stream sediments, sediment fractions, soils, and basement rocks from the mahaweli river and its catchment, sri lanka. chemie der erde, 73: 357-371. young /journal of tropical forestry and environment vol. 9, no. 02 (2019) 1-11 11 young, s.m., ishiga, h., roser, b.p. and pitawala, a., 2014. geochemistry of sediments in three sectors of trincomalee bay, sri lanka: provenance, modifying factors, and present environmental status. journal of soils and sediments. journal of soils and sediments, 14:204-217. young s.m. and ishiga, h., 2014a. environmental change of the fluvial-estuary system in relation to arase dam removal of the yatsushiro tidal flat, sw kyushu, japan. environmental earth sciences young, s.m. and ishiga, h., 2014b. assessment of dam removal from geochemical examination of kuma river, kyushu, japan. environmental monitoring and assessment. 186:8267-8289. zhang, l., ye, x., feng, h., jing, y., ouyang, t., yu, x., liang, r., gao, c. and chen, w., 2007. heavy metal contamination in western xiamen bay sediments and its vicinity, china. marine pollution bulletin, 54:974-982. zhang, j. and liu, c.l., 2002. riverine composition and estuarine geochemistry of particulate metals in china-weathering features, anthropogenic impact and chemical fluxes. estuarine, coastal and shelf science, 54:1051-1070. wanodya and perera /journal of tropical forestry and environment vol. 9, no. 01 (2019) 69-79 69 perception of generation y on waste disposal and waste management in sri lanka with special reference to undergraduates of private universities in colombo wanodya w.g.m.u.1, perera h.p.n.2* 1school of accounting and business, institute of chartered accountants of sri lanka, colombo, sri lanka 2department of sports science, faculty of applied sciences, university of sri jayewardenepura, nugegoda, sri lanka date received: 05-12-2018 date accepted: 22-04-2019 abstract solid waste piling has become a serious problem to sri lanka. urbanisation, industrialisation, and improvements in quality of life lead the increase in quantity and complexity of generated waste. the main purpose of this study is to determine the perception of undergraduates on waste, waste disposal mechanisms and waste management techniques in their living area. the research data obtained from one hundred and seventy three (n=173) undergraduate respondents from private universities located in western province, colombo 07. a self-administered pre-validated questionnaire was used and the questionnaire was developed according to the literature survey and adapted accordingly to suit the sri lankan context. the data collection method was cross sectional. spss16.0 was used for data analysis. data were analysed using cross-tab and chi square test. cronbach’s alpha with the present sample was 0.63. the results revealed that 51% of the respondents do not have any clue of where their service providers are dumping their waste and 53% had reported that they are not concerned about it. even though the responses are as such, 80% of the respondents had stated that they are aware that environmental degradation affects their families. the results revealed (based on p-value) that there is no association between gender and student perception on waste management. furthermore student’s concern about the environment and waste management was moderate. research reveals that there should be a proper mechanism to improve young generation’s concern about the environment and waste management to attain a sustainable future in the long term. keywords: waste, waste management, service providers, dumping waste, environmental degradation 1. introduction waste disposal and waste management has become a global issue. the most developed countries in the globe generates most the waste on earth however, the waste has not become a main issue in developed countries even though they are the large scale waste generators because such countries are technologically advanced and have well established proper waste management systems. dumping waste in urban and sub-urban areas has become an increasing problem in sri lanka specially in the western province, around colombo area, where no effective solutions has been taken (sabry, 2018). recent incidents such as fire at meethotamulla garbage dump site made the authorities to pay immediate attention on waste management in the urban and suburban areas in sri lanka. colombo, the commercial capital and the most urbanised city, is the largest producer of solid waste in sri lanka (gunaruwan and gunasekara, 2016). however, the issue of msw is most acute in the colombo municipal area and in the suburbs of colombo (bandara , 2011). *correspondence: udariwanodya@gmail.com issn 2235-9370 print/issn 2235-9362 online ©2019 university of sri jayewardenepura doi: https://doi.org/10.31357/jtfe.v9i1.3953 https://doi.org/10.31357/jtfe.v9i1.3953 70 figure 1: waste generating countries and scale of waste generation. the collection of municipal solid waste (msw) is the responsibility of corporations/ municipalities (sharholy et al., 2008). in sri lanka, msw collection was mainly done through community garbage collection points (authorized or unauthorized dump points) and house-to-house collection. however, the government still failed to manage msw up to the standard which ensure sustainable environment with less pollution. sri lankan government has taken actions in order to address this emerging issue on solid waste management but the expected success rates could not be achieved as planned. this could happen due to various factors such as weak institutional and legal framework, choice of technology, inadequate collection and transportation systems (longe et al., 2009), poor planning without considering all consequences that could affect the success of the solid waste management systems, implementation issues, lack of monitoring on the progress of the plan, absence of specialists or committed officers to lead the projects, less support from the public towards the project were some issues that could be observed in sri lankan context. unacceptable disposal of solid waste is one of the biggest environmental issues faced by the country at present (bandara, 2011). the rational man finds that his share of the cost of the wastes he discharges into the commons is less than the cost of purifying his wastes before releasing them. since this is true for everyone, we are locked into a system of “fouling our own nest” (ranasinghe, 2017) which leads to improper waste disposal practices. the issue regarding waste management needs to be observed in the eyes of the future generation because the sustainable environment practices needs to be established for the long term. therefore, the study aims to identify how the undergraduate students’ perception on solid waste management with special reference to the undergraduates at school of accounting and business, the institute of chartered accountants of sri lanka. sri lanka, with a current per-capita gross national product (gnp) of us$ 1350, is an island country in the indian ocean off the southern coast of india. it has a total land area of 65,610 km2 hosting a population of about 20 million. disposal of solid waste is a major environmental problem in sri lanka at present and has become a national issue. the national action plan of sri lanka has identified haphazard solid waste disposal to be one of the major causes for environmental degradation (bandara and wanodya and perera /journal of tropical forestry and environment vol. 9, no. 01 (2019) 69-79 71 hettiarachchi, 2010), (bandara, 2011). this is mainly due to increased consumption behaviour as a result of unplanned urbanization (menikpura et al., 2012), increased population, industrialisation and economic growths (sharholy et al. 2006; dhokhikah and trihadiningrum , 2012; khan et al., 2018; yukalang et al., 2018). the main component of solid waste (sw) is decomposable organic waste which has a range of 42% to 80.2%. other solid waste components, which appear in less portion, are paper, plastic, cloth, metals, glass, ash and others could also be identified (dhokhikah and trihadiningrum , 2012). the relative percentage of organic waste in solid waste is generally increasing with the decreasing socioeconomic status; so rural households generate more organic waste than urban households (sharholy et al., 2008). municipal solid waste (msw) of sri lanka typically consists of a very high percentage of perishable organic material which is about 65-66% by weight with moderate amounts of plastics and paper and low contents of metal and glass (bandara, 2011). in 1999, the estimated average solid waste generation in sri lanka was 6,500 tonnes/day. with a 1.2% population growth rate, total msw generation in 2009 was approximately 7,250 tonnes/day. in 1999, the average per capita msw generation was 0.89 kg/cap/day and has been predicted to reach 1.0 kg/cap/day by 2025 (menikpura et al., 2012). five typical problem areas can be identified in municipal solid waste management (mswm) of developing countries: i) inadequate service coverage, ii) operational inefficiencies of services, iii) limited utilisation of recycling activities, iv) inadequate management of non-industrial hazardous waste, and v) inadequate landfill disposal (ivy et al., 2013). the local authorities (las) are responsible for the collection and proper disposal of waste generated by the people within its territory. except for the municipality of colombo which has a separate solid waste management unit, the public health department of the local authority is responsible for solid waste management in addition to their other responsibilities including health and sanitation. the daily collection of msw in the country is about 2,683 tons of waste. however, the generated amount far outweighs this with almost negligible collection in rural areas of the country (bandara, 2011) municipal solid waste management (mswm) encompasses the functions of collection, transfer, resource recovery, recycling, and treatment. the primary target of mswm is to protect the health of the population, promote environmental quality, develop sustainability, and provide support to economic productivity (yongsheng et al., 2006). for the collection process, houseto-house solid waste collection is being performed by most of the municipal councils. in addition, community and roadside collections are also being practiced by some municipal councils (menikpura et al., 2012). according to a household survey conducted for the municipality of moratuwa, municipal waste collection is available to only 56% of the households. about 20% of the households dump their waste on the roadside and 8% dump the waste into pits in their own back yards. insignificant number of households uses alternative waste management techniques, while 7% compost their waste and practice recycling (bandara, 2011). the world bank reports vast amounts of uncollected waste in urban areas; estimates suggest between 40% and 70% of discarded materials remaining uncollected. this pollution leads to significant impacts on human health and the environment (yukalang et al., 2018). efficiency of waste management also depends on how people perceive waste and waste management practices of local authorities. according to kajor et al., 2015 and longe et al., 2009; holland and rosenberg (1996) stated that the perception is one’s capability is said to set a limit to what to do and ultimately what can be achieved. further, perception influences how a person views himself and the world around him and how it tends to govern his behaviour. individual perception is governed by past experience and present outlook, conditioned by values, moods, socials circumstances, individual expectation (kajor et al., 2015), cultural values, responses and success of solid waste management systems (longe et al., 2009). however, population perception of waste management describes the whole process of how the populace comes to know what is going on regarding best practices in waste 72 management, awareness and enlightenment programs through information, education (formal and informal), capacity building, coupled with implementation and execution of laws and regulations on proper waste management (kajor et al., 2015). generation y, who are also referred as millennials, who were born after 1980s (olejniczak and olejniczak, 2018) are the emerging generation who will be the young adults of a country. they are negatively described as lazy, narcissistic and prone to jump from job to job (main, 2017). elderly members of generation y have already entered job market and younger ones will enter it in following years. generation y is basically different from their predecessors from generation x and baby boomers generation (mackayova and balazova, 2011). thus the perception of these millennials are very important in efficiency of waste management practices. several links have been identified regarding social factors influencing citizens’ perceptions and attitudes towards environmental policies. indicative examples of such factors are income and educational level, age, social norms and the level of social trust (jones et al., 2010). the importance of human factor for the minimisation of waste and argue that waste could be prevented by changing the attitudes of the people. however, the involvement of people is being ignored from the waste management equation. for successful waste management practices, interdisciplinary approaches between all the stakeholders are essential (kulathunga et al., 2006). moreover, these factors have interrelationships (sharholy et al., 2006). past research has shown that the amount of waste generated is proportional to the population and the average mean living standards or the average income of the people. in addition, other factors may affect the amount and composition of waste. these are climate, living habits, level of education, religious and cultural beliefs, and social and public attitudes (bandara et al., 2007). the waste generation rate varies depending on the income levels of individuals (bandara, 2011) and households as well as on the degree of urbanisation of settlements. low-income households, for instance, generate half a kilogram of garbage per day while high-income groups average nearly double that amount (gunaruwan and gunasekara, 2016; jones et al., 2010). former surveys revealed that a high percentage of households from highand upper-middleincome groups enjoy municipal waste collection services and a lower percentage from the low income groups does so. further, they also revealed that a higher percentage of low-income and lower-middle income group households dispose of their waste along roads (bandara, 2011). the per capita solid waste generation rate varies among different cities. the per capita per day waste generation on the average was 0.85 kg in colombo municipal council (cmc), 0.75 kg in other municipal councils (mc), 0.60 in urban councils (uc) and 0.4 kg in pradeshiya shabhas (ps) (bandara, 2011). furthermore, gender disparities greatly influence the people’s attitude and perception on household waste management. recent findings however suggest that gender difference could influence people’s perception on solid waste management (longe et al., 2009). most of the 3r concept practitioners were women (dhokhikah and trihadiningrum , 2012). age is also expected to play a significant role as maturity could affect level of awareness on environmental health and sanitation. the data on age shows that subjects are matured adults whose reasoning level as regard household waste and management is expected to be high and thus facilitate public involvement in solid waste management process (longe et al., 2009). the influence of educational attainments could as well be an important factor that could influence people’s perception on waste management. this could negatively influence their perception and attitude on waste management in general (longe et al., 2009). the number of people in a household increases, there is a reduction in the per capita waste generation rate. thus in determining the waste generation of a municipality per household waste generation is as important measure as the per capita waste generation rate (bandara, 2011). the number of employed people in a household was also shown to be a contributing factor to waste generation. the average amounts of waste generated per households of wanodya and perera /journal of tropical forestry and environment vol. 9, no. 01 (2019) 69-79 73 different income levels can be used to predict the total amount of waste generated within a municipality (bandara, 2011). in cities public awareness was improved after receiving guidance concerning environmental issues (dhokhikah & trihadiningrum , 2012). in addition, various occupational groups have different attitudes towards the generation and controlling of waste (kulathunga et al., 2006). 2. methodology participants completed self-developed questionnaire adapted from above mentioned authors under the supervision of the researchers in order to obtain relevant information for the study. the population of the study was 173 undergraduates from the private universities, vested in colombo 07 geographical area where the population is recorded to be 312. the sample size was decided upon the table developed by krejcie and morgan in 1970 which depicts sample size for a given population size. the reliability of the questionnaire was assessed by calculating cronbach’s alpha. the cronbach’s alpha obtained with the present sample was 0.637. the conceptual framework was developed based on the previous research work conducted by (lutui, 2001) and adapted accordingly to suit sri lankan context. methods used to analyse data were cross tab and statistical package for social sciences (spss) version 20.0 was used to analyse data. a total of 173 subjects participated in the study. figure 2: conceptual framework. 3. results the descriptive statistics of the sample were as follows. according to table 1, most of the participants were female (54%) and males were 46%. age of team players ranged from 18 to 33 years. the age was categorized into four groups as below 20 years (4.1%), 21-25 years (90.1%), 25-30 (5.2%), and above 30 years (0.6%). the living areas were categories into three groups (table 1). as table 1 illustrates, more participants are from urban area (56.1%). most of them were studying for both degree and professional exams and are unemployed (63.6%). the average family members were 4-6. most of the families were in the range of rs.50,0001 -100,000 family income level (41%). the impact of gender on waste, waste disposal mechanism, and waste management techniques were also analysed using cross-tab. gender is considered as one of the standard demographic component of social sciences researches. according to table 2, most participants had responded that waste littering and look bad and waste influence on human health and environment. participants had given order preferences as their answers. according to table 3 the p value is more than 0.05, and hence cannot derive an association between the variables namely, littering looks bad, effect on human health, and effect on environment, with gender. demographic characteristics gender perception of respondents on waste management • priority concern about the waste in the area of living • household waste storage mechanism • disposal of solid waste • separation of waste • family commitment towards waste disposal • waste collection mechanism at your area. • effect of waste on environment • problems with current solid waste management system 74 table 1: descriptive statistics for respondents’ profile. variable frequency percentage gender male female 80 93 46% 54% age below 20 years 21-25 years 26-30 years above 30 years 7 156 9 1 4.1% 90.1% 5.2% 0.6% home town urban suburb rural 97 55 21 56.1% 31.8% 12.1% education only reading for degree degree and other professional qualifications 63 110 36.4% 63.6% employment unemployed working full time part time self employed 110 56 4 3 63.6% 32.4% 2.3% 1.7% total family members 3 or less than 3 4-6 members 7 and more than 7 members 33 132 8 19% 76.3% 4.7% occupation of the parents self employed private sector public sector other 58 68 38 9 33.5% 39.3% 22% 5.2% average family income less than rs.50,000 rs.50,001-100,000 rs.100,001-200,000 more than rs.200,000 36 71 43 23 20.8% 41% 24.9% 13.3% source: survey data 2018. table 2: priority concern about the waste in the area of living. gender littering and looks bad effect on human health effect on environment other most important (mi) 2nd choice 3rd choice mi 2nd 3rd mi 2nd 3rd mi 2nd 3rd male 65% 1% 34% 20% 76% 4% 5% 20% 65% 10% 3% 88% female 56% 1% 43% 22% 77% 1% 5% 22% 56% 17% 0% 83% % within gender 60% 1% 39% 21% 77% 2% 5% 21% 60% 14% 1% 85% source: survey data 2018. wanodya and perera /journal of tropical forestry and environment vol. 9, no. 01 (2019) 69-79 75 table 3: chi-square test summary (in your opinion which of these is a priority concern about waste in the area?). pearson chi-square asymp. sig. (2-sided) minimum expected count littering and looks bad 0.460 0.92 effect on human health 0.500 1.85 effect on environment 0.500 1.85 other 0.132 0.92 table 4: what do you use to store your household garbage in? (household waste storage mechanism). gender plastic bags cardboard bin other non storage mi 2nd 3rd mi 2nd 3rd mi 2nd 3rd 2nd 3rd 4th mi 5th% male 58% 43% 98% 36% 55% 10% 3% 88% 10% 90% female 51% 50% 100% 40% 50% 11% 0% 0% 11% 89% % within gender 54% 46% 99% 38% 52% 10% 1% 1% 11% 90% source: survey data, 2018. according to table 4 most people irrespective of their gender, used plastic bag and bins to drop waste, and a considerable proportion is there who do not store waste in any means. table 5: chi-square test summary (what do you use to store your household garbage in?). pearson chi-square asymp. sig. (2-sided) minimum expected count plastic bags 0.360 36.99 cardboard boxes 0.125 0.92 bins 0.752 7.86 other (to disposal vehicles) 0.307 0.92 non storage 0.916 8.21 according to table 4, the p value is more than 0.05, and hence cannot derive an association between the variables (i.e. use of plastic bags, cardboard boxed and bind or any other disposal mechanisms) with gender. table 6: where do you dispose your generated waste?. gender nearby container open spaces near home mi 2nd 3rd mi 2nd 3rd mi 2nd 3rd male 59% 16% 25% 25% 75% 41% 59% female 59.1% 10% 31% 31% 69% 41% 59% % within gender 59% 13% 28% 28% 72% 41% 59% source: survey data, 2018. according to table 6, most people irrespective of their gender, drop waste in nearby places and the next priority is given for nearby containers and near home respectively. 76 table 7: chi-square test summary. pearson chi-square asymp. sig. (2-sided) minimum expected count nearby container .360 10.17 open space .368 22.66 near home .959 32.83 according to table 7, the p value is more than 0.05, and hence cannot derive an association between the variables (i.e. waste disposal to nearby container, open space or near home) with gender. table 8: crosstab summary for q19-23. gender separation of different type of waste at your home? satisfaction with your current waste collection service participate in any community clean-ups activities or other voluntary clean-ups is waste management an environmental problem how your service provider disposes your collected waste environmental degradation has negative effect on your family are you concerned about the disposal methods of the service provider yes no yes no yes no yes no yes no yes no yes no male 50% 50% 75% 24% 54% 44% 75% 24% 54% 44% 81% 19% 43% 57% female 47% 51% 69% 30% 41% 57% 69% 30% 41% 57% 79% 21% 50% 50% % within gender 49% 51% 72% 27% 47% 52% 72% 27% 47% 51% 80% 20% 47% 53% p-value 0.409 0.644 0.220 0.6440 0.220 0.728 0.363 minimum expected value 0.920 0.920 1.850 0.9200 0.019 0.152 0.370 source: survey data, 2018. the above table 7 depicts the yes and no responses given by the respondents to the mentioned questions. half of the respondents (49%) said that they separate waste and another half (51%) that they do not separate waste. most respondents are satisfied with their current waste collection services (72%). more than half of the respondents (52%) reported that they or their family members had participated in waste clean-ups community services and simultaneously had reported that they see waste as an environmental problem. one of the main issues in relation to waste disposal are dumping waste to unoccupied lands by service providers, 51% of the respondents had said that they do not have any clue of where their service providers are dumping their waste and unfortunately 53% had reported that they are not concerned about where their service providers dump their waste. even though the responses are as such, 80% of the respondents had stated that they are aware that environmental degradation affect their families. table 9: identifying some of the main problems with current solid waste management system. gender waste lying around bad odour rats and flies mi 2nd 3rd mi 2nd% 2nd 3rd male 19% 59% 23% 81% 19% 22.5 78% female 24% 58% 18% 76% 24% 18.3 82% % within gender 21% 58% 20% 79% 21% 20.2 80% source: survey data, 2018. the order preference given for waste as a problem are bad odour, waste lying around and animals (rats and flies) respectively. according to table 10, the p value is more than 0.05, and hence cannot derive an association between the variables with gender. wanodya and perera /journal of tropical forestry and environment vol. 9, no. 01 (2019) 69-79 77 table 10: chi-square test summary (identifying some of the main problems with current solid waste management system). pearson chi-square asymp. sig. (2-sided) minimum expected count waste lying around .649 16.18 bad odour .433 17.10 rats and flies .491 16.18 source: survey data, 2018. 4. discussion there are countless numbers of researches available in waste management and waste management practices in different countries. this study was focused on to assess the impact of gender on the perception of respondents on waste management policies and practices. the decisions were made based on p value. according to the respective p values derived on behalf of priority concern about the waste in the area of living, household waste storage mechanism, disposal of solid waste, sseparation of waste, family commitment towards waste disposal, waste collection mechanism of the area concern, effect of waste on environment and problems with current solid waste management system revealed that there is no significant association of such variables with gender. the study results are partially agreeing with the studies conducted by longe et al. (2009). however the study results contradicts with the concept stated by kaoje et al. in 2017, “within the household setting there exist distinctive division of labour between males and females. the current practice of household waste handling is considered and designated as women’s responsibility” because as per the survey findings waste disposal practices do not have a significant association with gender. the study revealed that most of the participants are concerned about the effect on human health due to poor waste disposal practices. this could be mainly due to emerged health issues such as dengue which caused more deaths in the recent past. a significant important was placed on the fact that improper waste disposal causes the surrounding looks bad and littering. this could be mainly seen in the suburban areas in the country. the findings are complying with the study conducted by lutui (2001). majority of the selected sample households use plastic bins or polythene bags to drop the waste generated. these could be also dangerous in terms of environmental pollution because plastic and polythene are non-decaying materials in general thus could get accumulated in garbage dump sites. these will cause long term issues associated with the current waste disposal practices used in the households. the findings are complying with the study conducted by lutui (2001). nearby spaces were the mostly used method of waste disposal of the respondents. this is in line with the survey findings of khan et al. in 2018 which also revealed that approximately 50% of the waste generated is collected and transported to landfills with the remaining half left and dumped in the streets and vacant plots. this may create unauthorised garbage dumping places around households which is a good residence for stray animals and rats. even though the respondents have identified these consequences could occur as a result of their poor waste disposal practices, a majority have not taken actions to minimise such issues. most of the respondents were satisfied with the service provided in terms of waste collection. this could be because a majority of the population comprises from the colombo and suburban cities. this fact could be supported by the statistics of the central environment authority, sri lanka that 58% of the waste in colombo district is being collected. this was the highest waste collection percentage in sri lanka by 2014. however, this could be varying if the population composition varies with a majority from rural and suburban cities which are out of colombo area. 78 a greater majority of respondents were concerns about the impacts of waste but only a slight majority concerns about where their waste get disposed by the service providers and only a slight majority knows exactly where the waste get disposed. this could be due to typical nature of millennials who are less concerns about the social aspects and lazy to consider about such factors. the same applies when considering the participation in community waste cleaning projects, where just a slight majority concerns on it. the key solutions: development of a municipal waste management policy and an associated implementation plan; reduce the need for the landfill by generating a waste separation program (including education, infrastructure and economic policy), improving the existing waste collection system, and improving the financing of waste management could be considered (yukalang et al., 2018). 5. conclusion the research revealed that the there is no impact of gender on perception on waste disposal and waste management of generation y. further it highlights the need of awareness and effective waste management programmes in sri lanka that will reach the minds of the millennials. this is mainly because the millennials thinking patterns and behaviour is significantly different from other generations, thus to ensure a sustainable future it is required to ensure positive support through positive attitudes towards the environment, waste and waste management. acknowledgement the authors acknowledge prof. k. a. s. dhammika, senior lecturer, university of kelaniya, sri lanka, who is also the director at school of accounting and business, institute of chartered accountants of sri lanka for his support to make this a success. references bandara, n.j., 2011. municipal solid waste management-the sri lankan case. in proceedings of international forestry and environment symposium. bandara, n.j. and hettiaratchi, j.p.a., 2010. environmental impacts with waste disposal practices in a suburban municipality in sri lanka. international journal of environment and waste management, 6:107-116. bandara, n.j., hettiaratchi, j.p., wirasinghe, s.c. and pilapiiya, s., 2007. relation of waste generation and composition to socio-economic factors: a case study. environmental monitoring and assessment, 135:31-39. daily mirror, 2018 january 18. fire at meethotamulla garbage dump. fire at meethotamulla garbage dump. colombo, western province, sri lanka: daily mirror e-news paper. dhokhikah, y. and trihadiningrum, y., 2012. solid waste management in asian developing countries: challenges and opportunities. journal of applied environmental and biological sciences, 2:329335. gunaruwan, t. and gunasekara, w., 2016. management of municipal solid waste in sri lanka: a comparative appraisal of the economics of composting. nsbm journal of management, 27-45. haider, a., amber, a., ammara, s. and salee, k., 2015. knowledge, perception and attitude of common people towards solid waste management-a case study of lahore, pakisthan. international research journal of environment sciences, 100-107. ivy, n., uddin, m.m., and hossain, m.k., 2013. people’s perception on using waste bins in reduce, reuse and recycle (3rs) process for solid waste management (swm) in chittagong, bangladesh. international journal of applied science, technology and engineering research, 2:30-40. jones, n., evangelinos, k., halvadakis, c., sophoulis, c. and iosifides, t., 2010. social factors influencing perceptions and willingness to pay for a market-based policy aiming on solid waste management. elsevier, resources, conservation and recycling, 54:533-540. wanodya and perera /journal of tropical forestry and environment vol. 9, no. 01 (2019) 69-79 79 kajor, a., sabir, a., yusuf, s., jimoh, a. and raji, m., 2015. residents’ perception of solid waste disposal practices in sokoto, northwest nigeria. african journal of environmental science and technology, 94-102. khan, s., alvarez, l.c. and wei, y., 2018. sustainable management of municipal solid waste under changing climate: a case study of karachi, pakisthan. asian journal of environmental biotechnology, 23-32. kulatunga, u., amaratunga, r., haigh, r. and rameezdeen, r., 2006. attitudes and perceptions of construction workforce on construction waste in sri lanka. an international journal, 17:57-72. longe, e., longe, o. and ukpebor, e., 2009. peoples' percption on household solid waste management in ojo local government area in nigeria. iranian journal of environmental health, science and engineering, 209-216. lutui, v., 2001. waste management practices, perception and attitudes in tonga. mackayova, v., & balazova, v., 2011. characteristics of generation y and it’s future occupationcomparison of opinions. human resource management & economics, 5. main, d., 2017 september 08. livescience. retrieved from who are millenials?. menikpura, s., gheewala, s. and bonnet, s., 2012. sustainability assessment of municipal solid waste management in sri lanka: problems and prospects. journal of material cycles and waste management, 14:181-192. olejniczak, d. and olejniczak, j., 2018. changes in the attitudes of y generation members towards participation in the activities of municipalities in the years 2008-2017. ranasinghe, p., 2017 april 21. mirror business. sri lankan solid waste management theory and tragedy of commons. colombo, western province, sri lanka: daily mirror e-newspaper. sabry, h., 2018 august 26. no solution in sight for colombo’s garbage problems. colombo, western province, sri lanka: sunday leader. sharholy, m., ahmad, k., mahmood, g. and trivedi, r., 2008. municipal solid waste management in indian cities-a review. waste management, 459-467. sharholy, m., ahmad, k., vaishya, r. and gupta, r., 2006. municipal solid waste characteristics and management in allahabad, india. waste management, 490-496. yongsheng, z., henry, r. and jun, d., 2006. municipal solid waste management challenges in developing countries-kenyan case study. waste management, 92-100. yukalang, n., clarke, b. and ross, k., 2018. solid waste management solutions for a rapidly. international journal of environmental research and public health, 23. jayasekara et al. /journal of tropical forestry and environment vol. 9, no. 01 (2019) 59-68 59 microhabitat utilisation of endemic lizard calotes nigrilabris in the grasslands of horton plains national park, sri lanka jayasekara e.g.d.p., prabhath m.c., mahaulpatha w.a.d.* department of zoology, university of sri jayewardenepura, gangodawila, nugegoda, sri lanka date received: 20-02-2019 date accepted: 16-05-2019 abstract the endemic endangered agamid lizard calotes nigrilabris inhabits the grasslands of horton plains national park (hpnp) and it is restricted to a few localities in the central highlands of sri lanka. in this study, the microhabitat utilisation of calotes nigrilabris was investigated utilising line transects and quadrate method. the comparison of available microhabitat variables with occupied microhabitat variables revealed that there was a significant difference between some of the variables (man-whiteney u test, p<0.05) indicating that c. nigrilabris was selective in its microhabitat utilisation. based on pca analysis, amount and type of vegetation was the main determining factor of microhabitat preference of this species. ulex sp. cover (pc1, 0.606) and rhododendron sp. cover (pc2,-0.603) were significantly affecting the occupied microhabitat structure. microhabitat utilisation varied in the temporal and spatial scales also indicating clear resource partitioning between different maturity stages. the results of this study indicate that c. nigrilabris actively selects and utilises the most suitable grassland microhabitats of hpnp and provide important insights for the conservation and management of the species as well as its natural habitat. keywords: black-cheeked lizard, grassland habitat, resource partitioning, agamidae, ulex europaeus 1. introduction a habitat can be defined as the sum of the specific resources that are needed by organisms (thomas, 1979) which include food, cover, water and special factors needed by a species for survival and reproductive success (leopold, 1933). macrohabitat and microhabitat are two relatable terms which depend on the scale of landscape and relate more to a specific animal being studied rather than to a type of habitat (krausman, 1999). according to johnson (1980) microhabitat usually refers to finer scaled habitat features which are at the lower levels of the hierarchical structure of habitats. since lizards are ectothermal animals, they tend to depend highly on smaller microhabitats for thermoregulation. however microhabitat selection may also depend on morphology and behavioral preferences of the animal (adolph, 1990). according to arnold (1983) force of natural selection on specific aspects of morphology, physiology and behaviour lead to differences in functional capabilities, which, in turn, are adaptive for the differing demands of different environments (schulte et al., 2004). therefore, animal populations develop certain traits which increase their fitness in the given habitat (arnold, 1983) which is also reflected in microhabitat utilisation (adolph, 1990). the term microhabitat utilisation can be defined as the practical and effective use of the available microhabitats by a species. thus, understanding the microhabitat requirements and the utilisation of those microhabitats by a species requires considering different life history strategies, morphometry, behavioural characteristics as well as environmental parameters (krausman, 1999). *correspondence: mahaulpatha@sjp.ac.lk tel: +94 718251516 issn 2235-9370 print/issn 2235-9362 online ©2019 university of sri jayewardenepura doi: https://doi.org/10.31357/jtfe.v9i1.3952 60 horton plains national park is home for three of sri lanka’s agamid lizards, all of which are endemic to the island. critically endangered (cr) cophotis ceylanica and endangered (en) ceratophora stoddarti occur in its montane cloud forests (de silva, 2007). the association of endangered c. nigrilabris with the grasslands of hpnp and surrounding areas has long been observed (manamendraarachchi and liyanage, 1994; bahir and surasinghe, 2005; de silva, 2007; somaweera and somaweera, 2009; amarasinghe et al., 2011; somaweera et al., 2012). c. nigrilabris is usually considered a diurnal sub-arboreal species (das and de silva, 2005) that prefer low shrubs and ferns. this species is restricted to montane forests above 1300 m elevation (erdelen, 1984) and it is the only agamid species to occur in the tropical high altitude grasslands of the island (bahir and surasinghe, 2005). even though some qualitative information regarding the habitat utilization of c. nigrilabris is available in the published literature (de silva, 2007; somaweera and somaweera, 2009; amarasinghe et al., 2011) no quantitative studies have been done, especially regarding the microhabitat utilisation, except for the study conducted by somaweera et al. (2012) to find the effect of ulex europaeus on habitat selection of c. nigrilbris. in this research we focused on the ecological aspects of c. nigrilabris with reference to microhabitat utilisation to provide relevant information to bridge the gaps in data availability to help the conservation and management. therefore, the objectives of this study were to identify the microhabitat requirements, microhabitat preferences and utilisation of those microhabitats by this species. 2. methodology 2.1 study site we conducted the study for a period of one year from january to december 2016 in horton plains national park. it is located on the southern plateau of the central highlands of tropical island sri lanka (6°47'-6*50'n, 80°46'-80°50'e) (green, 1990; dwc, 2007). this is a unique national park in sri lanka with discrete weather patterns and climatic conditions which harbors a large number of flora and fauna with a high percentage of endemism (pethiyagoda, 2012). 2.2 grassland habitat we conducted sampling in the grassland (wet patana) habitat which makes up an area of 776 ha (25.8%) of hpnp. grasses generally known as ‘tussock grass” (chrysopogon nodulibarbis, andropogon polyptychos and garnotiaex aristata) are the more dominant plants in this habitat (dwc, 2007). “maha ratmal” (rhododendron arboreum) and “european gorse” (ulexe uropaeus) are commonly found scattered throughout these grasslands. invasive ulex europaeus sometimes grows as impenetrable stands threatening the native flora. abandoned potato terraces have been colonized by carpet grass (axonopus fissifolius) which gives the appearance of a lawn (dwc, 2007). 2.3 sampling we carried out our sampling work utilising visual encounter surveys (doan, 2003) along 200 m line-transects (garcia, 2008) in the grassland habitat. we recorded only the lizards we could observe within 2 m on either side of transect and up to a height of 4 m to reduce any possible bias caused by the variation in visibility. the maturity stage of each lizard (adult male, adult female, sub-adult male, subadult female and juvenile) was also determined based on morphometrics (mainly relative estimation of svl) (jayasekara et al., 2017) and secondary sexual characteristics when needed. we considered both sub-adult male and sub-adult female under one category called “sub-adult” in the data analysis. transect surveys were carried out by two people one day per month (for a period of one year) from 08.00 h to 17.00 h in three time periods; morning (08:00 h-11:00 h), midday (11:00 h-14.00 h) and evening (14:00 h-17:00 h), with a sampling effort of 216 person-hours and a total of 108 transects. we did observations by walking along transects at a very low speed (3-4 m/min) in order to carefully observe both sides of transect without disturbing the natural behavior of lizards (chandramouli, 2009). jayasekara et al. /journal of tropical forestry and environment vol. 9, no. 01 (2019) 59-68 61 2.4 microhabitat availability microhabitat availability was measured by putting five 1x1 m quadrates randomly along each transect using a random number table (díaz et al. 2006). at each quadrate we recorded percentage cover of each plant species, rocks, leaf litter and bare soil. ambient temperature and relative humidity at chest height (blair, 2009) were measured using kestrel 4,000 pocket weather meter, usa. we also measured soil characteristics like soil penetration (using soil penetrometer-land penetrometer inc.), soil ph and moisture content (using soil ph meter [kelway soil acidity (ph) and moisture tester]). a metal ruler was used to measure the leaf litter depth. we recorded the percentage cover of each plant species, rocks, leaf litter and bare soil within each quadrate. in occasions where lizards were occupying random quadrates, we considered them as occupied quadrates and did not consider them under available microhabitats. a total of 320 unoccupied quadrates were sampled during the study period. 2.5 microhabitat use of c. nigrilabris we broadly classified the perch types where we sighted c. nigrilabris as ground, leaf litter, shrub, tree trunk, tree-branch and tree-leaf. we recorded the perch type where we first sighted each c. nigrilabris. to study the preferred microhabitat 1x1 m quadrates were put along each transect having the point of each lizard sighting as the center. a number of different parameters at the center of each occupied quadrate were recorded as follows. we categorised and recorded perch light to lizard’s location as full sun light (75% or greater sunlight) filtered sun light (25% to 75% sunlight) and shade (less than 25% sunlight) (angert et al., 2002). photo analysis was assisted in determining the light percentage. perching plant species of lizards were identified and the percentage cover of each plant species within the quadrate was determined by visual estimation. we recorded percentage cover of each plant species, rocks, leaf litter and bare soil, ambient temperature, relative humidity, soil penetration, soil ph and moisture content, leaf litter depth, percentage cover of rocks, leaf litter and bare soil within each quadrate were also measured. a total of 303 occupied quadrates were sampled. 2.6 data analysis minitab version 17 statistical software package and microsoft excel were used for statistical analysis and graphical representation of results. principal components analysis (pca) together with eigen analysis was performed to find out important microhabitat variables of occupied quadrates. non parametric mann-whitney u-test at significance level (p=0.05) was conducted to compare the microhabitat variables between occupied and unoccupied quadrates of c. nigrilabris. sample data were checked for normality and other assumptions of parametric tests when required. one way anova (analysis of variance) was used to examine variations in perch height between different age classes of c. nigrilabris. non parametric kruskal-wallis test was performed when assumptions for parametric tests were not met. kruskal-wallis analysis was used to examine significant differences in perch plant preference. 3. results 3.1 microhabitat preference of c. nigrilabris characteristics of microhabitats occupied by c. nigrilabris were different from the available random unoccupied quadrate characteristics. variables that significantly differed include; ulex sp. cover, rhododendron sp. cover, tussock grass cover, fern (pteridium sp.) cover, other plant cover, bare soil percentage, temperature (ambient), relative humidity and soil moisture percentage. therefore, those variables correlated with microhabitat occupancy of c. nigrilabris (table 1). 62 table 1: characteristics of available habitat variables vs. occupied microhabitats (mean±sd). variable random unoccupied quadrate (n=320) occupied quadrate (n=303) mann-whitney u-test p value ulex sp. cover (%) 12.77±13.00 28.58±32.19 0.0001* rhododendron sp. cover (%) 13.58±20.41 25.59±30.23 0.0001* tussock grass cover (%) 28.41±17.25 14.109±14.91 0.0001* fern(pteridium sp.) cover (%) 8.75±13.01 12.112±14.66 0.0000* dwarf bamboo cover (%) 3.45±7.48 3.564±9.81 0.0787 other plant cover (%) 14.75±11.58 7.574±7.67 0.0001* cover of rocks (%) 1.606±3.40 1.436±3.66 0.0644 bare soil (%) 6.33±6.12 7.079±15.57 0.0000* leaf litter depth (cm) 4.403±2.41 4.607±5.55 0.0711 leaf litter cover (%) 11.53±8.31 11.271±10.39 0.2172 temperature (ambient) 23.823±4.27 21.445±3.75 0.0000* relative humidity (%) 76.60±11.79 73.002±14.37 0.0133* soil penetration (mpa) 11.71±2.32 12.041±2.61 0.3644 soil ph 6.73±0.07 6.7282±0.07 0.4097 soil moisture (%) 10.97±7.81 14.439±5.35 0.0001* *significantly different variables marked with “*” and in bold. first five axes of the pca analysis of microhabitat variables which were significantly different from available habitat characteristics accounted for 75.3% of the total variance according to the eigen analysis of the correlation matrix. the first principal component (pc1) correlated positively with ulex sp. (pc1, 0.606) cover having the highest impact on pc1. it correlated negatively with tussock cover. hence an increase in ulex sp. cover will lead to a decrease in tussock cover. the second component (pc2) gave high scores to sites with high values of rhododendron sp. cover (pc2, -0.603). pc3 correlated negatively with rhododendron sp. (pc3, -0.513) cover and positively with bare soil cover (pc3, 0.577). soil moisture percentage, other plant cover and relative humidity were significant respectively in pc4 and pc5. the overall pca result indicated that availability of different plant species (vegetation) is important in deciding the preferred microhabitat of c. nigrilabris (table 2). table 2: factor loadings for the first five principal component (pc) axes of occupied microhabitat variables. variable pc1 pc2 pc3 pc4 pc5 (oq) ulex sp. cover 0.606 0.379 0.163 -0.073 0.029 (oq)rhododendron sp. cover -0.097 -0.603 -0.513 0.032 0.074 (oq) tussock cover -0.51 0.325 -0.062 0.043 -0.282 (oq)fern (pteridium sp.) cover -0.472 0.414 0.004 -0.113 -0.039 (oq) other plant cover -0.342 -0.033 0.265 0.128 0.615 (oq) bare soil -0.017 -0.251 0.577 0.131 -0.153 (oq) temperature (a) -0.105 -0.247 0.473 -0.143 0.27 (oq) soil moisture 0.003 -0.044 0.109 0.872 -0.291 (oq)relative humidity 0.108 0.296 -0.261 0.405 0.595 *significant variables of each axis are in bold. 3.2 microhabitat variables in occupied quadrates c. nigrilabris preferred microhabitats with high percentages of larger grassland plant species like ulex sp. (28.58±32.19)% and rhododendron sp. (25.59±30.23)%. the percentages of tussock grass (14.11±14.9)% and other plants (7.57±7.67)% were relatively low in occupied microhabitats of c. nigrilabris when compared to random sites. average percentage of fern (pteridium sp.) cover was 12.11±14.66%. average ambient temperature and substrate temperatures of the preferred microhabitats were (21.45±3.75)o c and (20.22±4.00)o c respectively. bare soil percentage cover (7.08±15.57)% and jayasekara et al. /journal of tropical forestry and environment vol. 9, no. 01 (2019) 59-68 63 soil moisture percentage (14.44±5.35)% recorded high average values. average value for relative humidity was (73.00±14.37)% within microhabitats (table 3). table 3: microhabitat variables in occupied quadrates. variable mean±sd n=330 minimum maximum ulex sp. cover (%) 28.58±32.19 0 60 rhododendron sp. cover (%) 25.59±30.23 0 80 tussock grass cover (%) 14.11±14.91 5 60 fern (pteridium sp.) cover (%) 12.11±14.66 0 40 other plant cover (%) 7.57±7.67 5 40 bare soil (%) 7.08±15.57 0 25 ambient temperature (ºc) 21.45±3.75 2 30.9 substrate temperature (ºc) 20.22±4.00 11 31.2 relative humidity 73.00±14.37 61 98.2 soil moisture (%) 14.44±5.35 5 40 3.3 perch type preference of c. nigrilabris we observed the highest average percentage of individuals perching on branches (55.12±11.97)%. second most preferred perch type of c. nigrilabris was leaves (35.84±14.23)%. relatively low percentages of lizards were perching on shrubs (3.33±5.53)% and ground (5.49±8.3)%. very low percentage of lizards (0.22±0.76)% used tree trunks for perching. (figure 1a). 3.4 preferred perch plant of different maturity stages there was a significant difference in preferred perch plant within maturity stages of c. nigrilabris adult male, adult female, sub-adult and juvenile [kruskal-wallis, p<0.05]. highest percentage of adult males was recorded perching on rhododendron sp. (75.27±17.25) % (figure 3a). most preferred perch plant of adult females was ulex sp. (70.88±14.29) % (figure 3b). a high percentage of sub-adults were observed perching on ulex sp. (35.05±30.72) % while their second most preferred plant species was rhododendron sp. (figure 3e). there was no significant difference in average percentage of juveniles observed in different plant species [kruskal-wallis, p=0.071, p>0.05]. however, juveniles most preferred rhododendron sp. and fern–pteridium sp. (figure 1b). 3.5 diurnal perch light preference in the morning time period highest percentage (78.47%) of c. nigrilabris were perching in full sun light. filtered sun light and shaded perches were used by 10.42% and 11.11% of lizards respectively in the morning. during mid day time period lizards used all three perch types in approximately equal amounts (31.88%, 30.43 % and 37.68 %). most used perch light condition in the evening time period was shade (82.02 %). (figure 2a). 3.6 diurnal perch height variation in maturity stages perch height varied significantly between different maturity stages of c. nigrilabris [anova, f=21.93, p<0.05]. average perch heights of adult males (103.60±63.48) cm and females (93.28±54.04) cm were significantly higher than sub-adults (67.40±42.07) cm and juveniles (26.03±36.58) cm. average perch height juveniles was the lowest and it was significantly different from the average perch height of sub-adults and the two adult maturity stages. there was no significant difference in the observed average perch height in the three time periods (anova, p>0.05). however, average perch height increased from morning to mid day. we observed a decrease in the average perch height in the evening time period in all four maturity stage categories (figure 2b). 64 figure 1: a-perch type preference of c. nigrilabris; b-perch plants of different maturity stages. figure 2: a-diurnal perch light preference of c. nigrilabris; b-diurnal perch height variation of different maturity stages (af-adult female, j-juvenile, am-adult male, sa-sub-adult). figure 3: a=c. nigrilabris adult male; b=c. nigrilabris adult female preying near the flowers of ulex europeus; c=arial view of an adult male c. nigrilabris being camouflaged among the rhododendron sp. leaves; d=acrobatic movement of female c. nigrilabris between thorny ulex sp. branches; e=a sub-adult female on the leaves of rhododendron sp.; f-a juvenile on the leaves of fern (pteridium sp.). a b b a jayasekara et al. /journal of tropical forestry and environment vol. 9, no. 01 (2019) 59-68 65 4. discussion c. nigrilabris was selective in its use of microhabitats. most of the observed variables within occupied microhabitats of c. nigrilabris were significantly different from the variables that were available in random unoccupied sites. therefore, variables such as ulex sp. cover, rhododendron sp. cover, tussock grass cover, fern (pteridium sp.) cover, other plant cover, bare soil percentage, temperature (ambient), relative humidity and soil moisture percentage were the determining factors of the microhabitat of c. nigrilabris. according to the pca results, ulex sp. cover, rhododendron sp. cover, tussock grass cover, and other plant cover were significantly affecting the microhabitat conditions. therefore it can be concluded that available vegetation type directly affects the microhabitat utilisation of c. nigrilabris. high percentages of larger grassland plant species like ulex sp. (28.58±32.19%) and rhododendron sp. (25.59±30.23%) were present within the occupied microhabitats. both of these plants were utilised by c. nigrilabris for a number of different behaviours. lizards tend to bask on leaves or branches of these two plant species in the morning sun light. they perch near the flowers of either ulex sp. or rhodhodendron sp. to catch the prey that is attracted to the nectar of these flowers. they also used these plants for resting and sleeping. we observed courtship behaviour on rhodhodendron sp. leaves which are broad and relatively rigid. thorny ulex sp. plant also provides good refuge from the possible predators of c. nigrilabris. somaweera et al. (2012) also suggested this type of a relationship between ulex sp. (european gorse) and c. nigrilabris. these two plants are also the only species that grow several meters taller than the dominant grasses of the grassland habitat. pca results indicate that increase in percentage cover of these two species leads to the decrease in the cover of tussock grasses within microhabitats. hence, mean percentage cover of tussock grass (14.11±14.91%) and other plants (7.57±7.67%) were relatively low in occupied sites than random sites. fern (pteridium sp.) was another frequently occurring plant within preferred microhabitats but in rather low percentages (12.11±14.66%). ambient temperature and substrate temperatures of occupied microhabitats were significantly different from the random unoccupied. this result can be attributed to the thermoregulatory behaviour of c. nigrilabris and lizards as a whole. since lizards are ectothermic animals, the environmental temperature has a high impact on their body temperature. therefore, they tend to utilise microhabitats which provide them suitable temperature conditions. hence, c. nigrilabris was selective in microhabitats with such conditions. bare soil percentage cover (7.08±15.57%) and soil moisture percentage (14.44±5.35%) were another two variables that were significantly higher in occupied microhabitats. these two factors increased the presence of egg laying females providing suitable conditions for them, which in turn increased the number of individuals of other maturity like newly hatched juveniles and mate seeking adult males in the nearby microhabitats. dwarf bamboo cover, leaf litter depth, leaf litter cover, soil penetration and soil ph did not vary significantly between occupied microhabitats and unoccupied random sites. therefore, we can consider those factors less important and not having a high impact on microhabitat selection and utilisation of c. nigrilabris. furthermore, leaf litter amount was relatively low within the grassland habitat in general since not many woody plants were occurring. however, top soil layer was a thick humus layer within most of the grassland habitat which is considered slightly acidic as person (1899) mentioned (pethiyagoda, 2012) and results of the present study go in accordance with that. from the available perch types within their microhabitat, c. nigrilabris mostly used plant leaves and branches for perching indicating that it is an arboreal species as somaweera and somaweera (2009) and amarasinghe et al. (2011) described. a lower percentage of individuals were perching on tree trunks. this result may be related to the greenish body colour of this species which is easily camouflaged with leaves and leafy branches rather than darker tree trunks. they were also found on low shrubs and on the ground as well. we observed ground foraging during sunny mornings where they fed on small 66 invertebrates. therefore, c. nigrilabris can be considered as a sub-arboreal species in concordance with karunarathna et al. (2011). since c. nigrilabris is largely arboreal and their microhabitat preference was highly determined by the vegetative cover. therefore, it was interesting to study the perch plant preferences of this species. the most preferred perching plants of c. nigrilabris were rhododendron sp. and ulex sp. however there was a significant difference between preferred perch plant of different age classes. adult males (figure 3a) mostly preferred rhododendron sp. whereas adult females preferred ulex sp. (figure 3b, d). we can attribute this result to the body colour difference between the two genders. adult males with relatively darker green body colour were better adapted to utilize rhododendron sp. which also has leaves with a darker shade of green. the triangular heads of matured males with black bands on the upper lips which easily merge with rhododendron sp. leaves makes it difficult for the aerial predators to spot them. sometimes even the dorsal scales of the head region were also occupied with blackish edges resembling the venation of leaf blades making them better camouflaged (figure 3c). in contrast adult females with relatively lighter body colour preferred ulex sp. which has a similar shade of green. thorny branches of ulex sp. provide them protection while making up a rich microhabitat with high abundance of nectaring insect species as food sources. relatively smaller bodied females were able to move around the ulex sp. bushes with ease than larger bodied males further separating the two genders into these two plant species. however there were shifts in usual perching plants of these maturity stages in specific behaviours. we observed adult males preying for insects on ulex sp. during periods with high insect densities around ulex sp. flowers. during heavy ground frost conditions both males and females were resting and sleeping under the broad leaf blades of rhododendron sp. in all courtship behaviours observed females moved on to rhododendron sp. plants where males were perching. subadults (figure 3e) used both these plant types. however percentage of individuals that used ulex sp. for perching was slightly higher. juveniles mostly preferred young rhododendron sp. plants that were close to the ground. another important result was high percentage of juveniles that used to perch on leaves of fern-pteridium sp. juveniles which have the lightest shade of green among the five maturity stages were benefited by perching on these fern leaves (figure 3f) which were also light green in colour during young stage. diurnal perch light preference of c. nigrilabris varied in different time periods of the day. to cope with the temporal variation in the thermal environment, lizards need precise thermoregulation strategies which involve flexible use of structural habitat (porter et al., 1973; adolph, 1990). according to bennett (1980) many lizard species have a relatively narrow range of preferred body temperatures and it in turn corresponds to various physiological optima. because of the spatial variation of thermal microclimates, thermal biology and habitat use are interrelated (roughgarden et al., 1981; waldschmidt, and tracy, 1983; grant and dunham, 1988; adolph 1990). during the morning time period c. nigrilabris spent most of the time in full sunlight which provide them required thermal energy for their activities. to maintain optimal body temperatures they were utilising more filtered sun light and shaded perches in the mid day and evening time periods. there was a significant difference between average perch height of different age classes. adult males were occupying the highest perches closely followed by adult females. average perch heights of sub-adults and juveniles were significantly lower than adults. juveniles were perching at the lowest level more close to the ground. this result indicates a clear resource partitioning between the four age classes. this behaviour would help them to utilise their microhabitat more effectively by sharing the resources between maturity stages. even though average perch height of any of the age classes did not vary significantly in temporal scale, we could observe some variation in average perch height between the three time periods considered. perch height gradually increased from morning to mid day to reach a peak height for each age class. this result indicates that c. nigrilabris start from lower sleeping perches to jayasekara et al. /journal of tropical forestry and environment vol. 9, no. 01 (2019) 59-68 67 reach thermally suitable perches to help their activity. they used high perches for basking and feeding during morning and mid day time periods. in all maturity stages perch height gradually decreased from mid day to evening. a similar behaviour has been observed by de silva (2007) and somaweera and somaweera (2009). this is because c. nigrilabris descend down to sleep in more thermally preferable lower shrubs and grasses during colder late evenings and nights. 5. conclusions c. nigrilabris in the grasslands of hpnp was actively selecting its microhabitats. we can conclude that ulex sp., rhododendron sp. and fern (pteridum sp.) are the most important plants for the survival of this species in the grasslands habitat. however, it is not applicable to the areas outside the park where the habitat composition is different. most importantly ulex sp. and pteridium sp. are considered as invasive species. therefore, eradication programs (which are currently in operation) of these plant species should be re-evaluated to ensure that it would not negatively affect the survival of this grassland adapted endangered lizard. furthermore, clear resource partitioning in microhabitat selection and microhabitat utilisation between different maturity stages of c. nigrilabris has allowed it to thrive in the grasslands and to be the only agamid to do so. present study in the grasslands habitat of hpnp generated important data regarding the microhabitat utilisation of c. nigrilabris. this may aid in present and future conservation (in-situ and ex-situ) and management of this unique endangered endemic lizard species as well as the grassland habitat as a whole. acknowledgement we acknowledge the generous corporation of the horton plains national park staff, department of wildlife conservation for granting permission (permit no. wl/3/2/9/16) to conduct this research, university of sri jayewardenepura and department of zoology, for the facilities granted to conduct this research, idea wild for providing us field instruments which were of great value during field excursions. references adolph, s.c., 1990. influence of behavioral thermoregulation on microhabitat use by two sceloporus lizards. ecology, 7:315-327. amarasinghe, a.a.t., tiedemann, f. and karunarathna d.m.s.s., 2011. calotes nigrilabris peters 1860: a threatened highland agamid lizard in sri lanka. amphibian and reptile conservation, 5:33-43. angert, a.l., hutchison, d., glossip, d. and losos, j.b., 2002. microhabitat use and thermal biology of collared lizard (crotaphytus collaris collaris) and the fence lizard (scleroporous undulatus hyacinthinus) in missouri glades. journal of herpetology, 36:23-29. arnold, s.j., 1983. morphology, performance and fitness. american zoologist, 23:347-361. bahir, m.m. and surasinghe, t.d., 2005. a conservation assessment of the sri lankan agamidae (reptilia: sauria). raffles bulletin of zoology, 12: 407-412. bennett, a.f., 1980. the thermal dependence of lizard behaviour. animal behavior, 28:752-762. blair, c., 2009. daily activity patterns and microhabitat use of a helothermic lizard, ameiva exsul (squamata: teiidae) in puerto rico. south american journal of herpetology, 4:79-185 chandramouli, s.r., 2009. status and microhabitat prefference of otocriptis beddomii boulenger, 1885 (reptilia:agamidae) in ponumudi hills, western ghats, kerala,india. taprobanica, 1:107-110 das, i., de silva, a., 2005. a photographic guide to snakes and other reptiles of sri lanka, 2nd ed. london, new holland. de silva, a., 2007. the diversity of horton plains, sri lanka. vijitha yapa, colombo, sri lanka. díaz, j.a., monasterio, c. and salvador, a., 2006. abundance, microhabitat selection and conservation of eyed lizards (lacerta lepida): a radiotelemetric study. journal of zoology, 268:295-301. 68 doan, t.m., 2003. which methods are most effective for surveying rain forest herpetofauna. journal of herpetology, 37:72-81. dwc, 2007. biodiversity baseline survey: horton plains national park. consultancy services report prepared by green, mjb (ed.), de alwis, smdau, dayawansa, pn, how, r, singhakumara, bmp, weerakoon, d, wijesinghe, mr, ard inc in association with infotech ideas and greentech consultants. sri lanka protected areas management and wildlife conservation project (pam&wcp/consult/02/bdbs), department of wildlife conservation, ministry of environment and natural resources, colombo, 40. erdelen, w., 1984. the genus calotes (sauria, agamidae) in sri lanka: distribution patterns. journal of biogeography, 11:515-525. garcia, d., 2008. population density in podarcis lilfordi (squamata, lacertidae), a lizard species endemic to small islets in the balearic islands (spain). amphib reptil, 29:49-60. grant, b.w. and dunham, a.e., 1988. thermally imposed time constraints on the activity of the desert lizard sceloporus merriami. ecology, 69:167-176. green, m.j.b., 1990. iucn directory of south asian protected areas. iucn 216-219 jayasekara, e.g.d.p, prabhath, m.c. and mahaulpatha w.a.d., 2017. maturity stage categorisation of endemic lizard (calotes nigrilabris) in the grasslands of hpnp. wild lanka, 5:046-051. johnson, d.h., 1980. the comparison of usage and availability measurements for evaluating resource preference. ecology, 61:65-71. karunarathna, d.m.s.s. and amarasinghe, a.t., 2013. behavioural ecology and microhabitat use by lyriocephalus scutatus (linnaeus, 1758): a monotypic genus in sri lanka (reptilia: agamidae: draconinae) with notes on the taxonomy. russian journal of herpetology, 20:1-15. karunarathna, d.m.s.s., pradeep, w.a.a.d.g., peabotuwage, p.i.k. and de silva m.c., 2011. first report on the ovipositional behaviour of calotes nigrilabris peters, 1860 (reptilia: sauria: agamidae) from the central massif of sri lanka. russian journal of herpetology, 18:111-118. krausman, p.r., 1999. some basic principles of habitat use. grazing behavior of livestock and wildlife, 70:85-90 leopold, a., 1933. game management. charles scribner's sons, new york, 481 manamendra-arachchi, k., liyanage, s., 1994. conservation and distribution of the agamid lizards of sri lanka with illustrations of the extant species. journal of south asian natural history, 1:77-96 pethiyagoda, r. (ed.), 2012 horton plains: sri lanka’s cloud-forest national park. wildlife heritage trust. sri lanka porter, w.p., mitchell, j.w., beckman, w.a. and dewitt c.b., 1973. behavioral implications of mechanistic ecology. oecologia, 13:1-54. roughgarden, j., porter, w. and heckel d., 1981. resource partitioning of space and its relationship to body temperature in anolis lizard populations. oecologia, 50:256-264. schulte, j.a., losos, j.b., cruz, f.b. and núñez, h., 2004. the relationship between morphology, escape behaviour and microhabitat occupation in the lizard clade liolaemus (iguanidae: tropidurinae*: liolaemini).journal of evolutionary biology, 17:408-420. somaweera, r. and somaweera, n., 2009. lizards of sri lanka: a color guide with field keys. chimaira, germany. somaweera, r., wijayathilakal, n. and bowatte, g., 2012. does the invasive shrub ulex europaeus benefit an endemic sri lankan lizard?. herpetol conservation and biology, 7:219-226. thomas, j.w., 1979. wildlife habitats in managed forests: the blue mountains of oregon a washington. u.s.d.a., forest service handbook 553, washington, d.c. waldschmidt, s., and tracy, c.r., 1983. interactions between a lizard and its thermal environment: implications for sprint performance and space utilisation in the lizard uta stansburiana. ecology, 64:476-484. sample project report meetiyagoda et al. /journal of tropical forestry and environment vol. 7, no. 02 (2017) 49-61 49 performance of tropical vertical subsurface flow constructed wetlands for leachate treatment at different hydraulic loading rates t.a.o.k. meetiyagoda1, n.j.g.j. bandara2, k.b.s.n. jinadasa3, c.s. kalpage4 and c.d.k. pathirana2 1postgraduate in environmental and water engineering, department of civil engineering, university of peradeniya 2department of forestry and environmental science, university of sri jayewardenepura 3department of civil engineering, university of peradeniya 4department of chemical & process engineering, university of peradeniya date received: 29-10-2017 date accepted: 20-12-2017 abstract this study is focused on the investigation of three different types of plant species namely; narrow leaf cattail (typha angustifolia), green bulrush (scirpus atrovirens) and umbrella palm (cyperus alternifolius) for treatment of leachate. twelve laboratory scale subsurface flow constructed wetland models were operated in batch mode. four models, each containing similar plant species were fed with synthetic leachate having four different concentrations (25%, 50%, 75% and 100%) and 7 days hrt was given. the duration of a batch run was 12 weeks. removal efficiencies of bod5, cod, po4 3-, tc, and tn were measured. evapotranspiration (et) loss of each test run was also assessed. according to the results, the constructed wetland planted with umbrella palm and fed with 25% leachate showed the best pollutant removal efficiencies of 99.26% for bod5, 99.61% for cod, 98.78% for tn and 97.34%for tc. highest et potential of 93.57% was also observed from the constructed wetland with umbrella palm fed with 25% leachate. two way anova analysis was carried out for each plant species and leachate concentration and the umbrella palm species was identified as the best for leachate treatment. key words: constructed wetlands, landfill leachate, plant species, pollutant removal 1. introduction solid waste disposed in landfills are stabilized by combination of physical, chemical and microbial processes. as a result of landfill degradation, a liquid known as leachate is formed (tyrrel et al., 2002). landfill leachate is a highly complex wastewater. due to anaerobic conditions and long retention times prevailing in landfills, the landfill leachate usually contains high concentrations of nutrients, organic compounds and heavy metals which, if not properly collected and treated, can cause serious pollution by contaminating surface and groundwater sources (dorota and ewa, 2008; christansen et al., 1994). although several physical, chemical and biological treatment processes can be employed to minimize adverse environmental impacts of landfill leachate, they can be expensive in the construction, operation and may also require high-skilled laborers for operation (sawaittayothin and polprasert, 2007). *correspondence: kasun.pgwe17@eng.pdn.ac.lk tel: issn 2235-9370 print / issn 2235-9362 online © university of sri jayewardenepura mailto:kasun.pgwe17@eng.pdn.ac.lk 50 constructed wetlands (cws) are engineered systems which simulate the same processes that occur in natural wetlands, within a more controlled environment (kadlec and knight, 1996). cws have reasonably a small ecological footprint, which has been designed and implemented in accordance with the natural processes involving wetland vegetation, soils, and the associated microbial assemblages to assist in treating wastewaters. these systems have been effective in treating various types of waste waters, due to its support for diverse population of microbial communities and it offers quiescent conditions for sedimentation, adsorption, filtration, and ion exchange (cothren et al., 2002; verhoeven et al., 2006). since cw systems could potentially tolerate variable volumes of water and varying contaminant levels, it is highly applicable for treating landfill leachate (akinbile et al., 2012). several studies have been conducted on the factors that can affect contaminant removal in cws treating landfill leachate (yalcuk et al., (2009). lavrova et al., (2011) studied the effect of the flow direction on the treatment efficiency in the cws. kietlińska and renman (2005) reported that recirculation of treated effluent positively effects the substrate media. the variation of the performance with the type of pre-treatment was reported by wojciechowska et al., (2010). although majority of previous studies had used domestic or municipal wastewater to investigate the role of the plant species in cws (allen et al., 2002), studies done on industrial wastewaters for example paper-mills (abira et al., 2003), tannery (calheiros, et al., 2007), and fish-farm (naylor et al., 2003) and ground water (lin et al., 2002) are also available. the effect of loading rates was the most common factor evaluated along with plant species (brisson and chazarenc, 2008). two or more loading rates were either evaluated simultaneously with plant species in a factorial experimental design (with or without replicates) or by modifying loading rates over time in the same units and comparing the different time series. it is commonly accepted that macrophytes play an essential role in cws. brix (1997) and stottmeister et al. (2003) reported that macrophytes provide a large surface area for an attached microbial growth and supply reduced carbon and oxygen in the rhizosphere. the reduced flow velocity by macrophytes stabilized the surface of the bed and insulated the surface against frost in the winter. previous studies indicated that the type of the plant is often considered minor in subsurface flow cws for pollutant removal (mander et al., 2003), while some other studies revealed that the growth characteristics of different plant species may affect the potential for uptake and transformation of nutrient and heavy metals (tanner, et al., 1996; maltais-landry et al., 2009).benefits of macrophytes have been repeatedly demonstrated, but, it remains unclear whether significant differences exist in the removal efficiencies among plant species of comparable life forms and sizes (brisson and chazarenc, 2008). even though several cw studies with plant species are reported in the literature, there has been a dearth of information on the assessment of plant species on the removal efficiency of contaminants from landfill leachate. therefore, the primary objective of this study is to i) evaluate the effect of plant species towards the cw performance when treating landfill leachate; and ii) to find the most appropriate leachate concentration to be introduced to a constructed wetland system. 2. materials and method 2.1 plant species three plant species namely narrow leaf cattail (typha angustifolia), green bulrush (scirpus atrovirens) and umbrella palm (cyperus alternifolius), were selected for this study. *correspondence: mohammadqasimkhan@yahoo.com *correspondence: mohammadqasimkh *correspondence: mohammadqasi http://www.sciencedirect.com.ezlibproxy1.ntu.edu.sg/science/article/pii/s0956053x12000840#b0205 meetiyagoda et al. /journal of tropical forestry and environment vol. 7, no. 02 (2017) 49-61 51 2.2 experimental design twelve (12) identical lab scale subsurface flow constructed wetland (ssf cw) models were constructed using plastic vessels each with dimensions of 25cm×20 cm×34 cm (length×width×depth). a sampling point (faucet) was fixed at 3 cm from the bottom of each cw model for the collection of treated effluents. the faucet inlet was covered with a plastic net to prevent debris from clogging the sampling point. gravel, sand and silt were used as the substrate media in each cw. a 15 cm gravel layer, 10 cm sand layer and a 5 cm loam soil layer were placed from bottom to top to facilitate favorable conditions for plant growth. a plastic net was placed between soil and gravel layers to minimize disturbances to the silt layer. one plant species was planted in 4 cws so that 12 models were planted with 3 species of plants. plant density in each model was maintained at 3 shoots per cw. 2.3 synthetic leachate stock solution of synthetic leachate was prepared according to the formula presented by jamie et al., (2004). the concentration of synthetic leachate is given in table 1. four different feed solutions (25%, 50%, 75% and 100% of stock concentrations) were prepared by diluting the stock solution with normal tap water. table 1: synthetic leachate composition common chemical unit: g per liter sugar 1000 g ch3coona 100 g k2hpo4 2.22 g nahco3 35.72 g k2co3 35.37 g nacl 9.96 g cacl2 15.96 g mgcl2 .6h2o 15.89 g mgso4. 7h2o 8.04 g co(nh2)2 1000,g trace heavy metal unit: mg per liter feso4 200 h3bo4 5 znso4.7h2o 5 cuso4.5h2o 4 mnso4.7h2o 50 (nh4)6mo7o24.4h2o 5 al(so4)3.16h2o 3 coso4.7h2o 15 niso4.6h2o 50 96% conc. h2so4 (analr) 1 ml 52 2.4 leachate loading initially all 12 cw models were fed with tap water and allowed for plant shoots to stabilize (to develop couple of leaves). once stabilised, the first cw model was fed with 5 l of 25% leachate using a watering can, manually. the second cw model with the same plant species was fed with 50% leachate solution, the third one with 75% and the last one with 100% solutions. this procedure was repeated for all 3 types of plants species. cw models were operated in batch mode with a hydraulic retention time (hrt) of 7 days. after keeping intact for 7 days, leachate was drained through the sampling faucet. the leachate volume remaining after 7 days of batch operation was also measured. water quality was tested for 5-day biochemical oxygen demand (bod5), chemical oxygen demand (cod), total nitrogen (tn), phosphate concentration (po4 3-) and total carbon concentration (tc).the above procedure was repeated for all 12 models for 12 consecutive batches. 2.5 evapotranspiration (et) loss in cws, reduction of wastewater volume occurs with time due to both evaporation and transpiration, which is known as the evapotranspiration (et) loss. this may have an effect on the treatment efficiency of cws. the et loss was estimated as per the equation 1.   100 5 periodretention of days 7after remaining litresin volumeleachate5 loss et    (1) 2.6statistical analysis pollutant removal efficiencies of 5 selected parameters (cod, bod5, tn, tc, po4 3-) were estimated according to the equation 2. 100 ionconcentrat initial ionconcentrat final-ionconcentrat initial efficiency removal  (2) removal efficiencies obtained from 12 cws for 12 repeated tests were subjected to two way anova analysis. the analysis was conducted using minitab (16.2.4.0) software. the analysis was conducted to determine significant differences among different systems and comparison of means was done in order to find the most appropriate plant species and best leachate concentration for the optimal removal of contaminants. 3. results and discussion in this study three plant species (cattail, bulrush and umbrella palm) were grown in 12 identical ssf cw sand tested for 4 different leachate concentrations (25%, 50%, 75% and 100% of stock leachate concentration). tests were conducted in batch mode with a 7 day hrt. pollutant removal efficiencies of bod5, cod, po4 3-, tc, and tn were estimated. percentage reduction of leachate volume during the 7 day retention period was also assessed. since the pollutant levels in natural leachate could vary with the climatic condition, solid waste composition and many other variables; synthetic leachate prepared according to the formula presented by jamie et al. (2004) was used for this study. composition of the stock leachate solution is given in table 2. meetiyagoda et al. /journal of tropical forestry and environment vol. 7, no. 02 (2017) 49-61 53 table 2: concentration of synthetic leachate stock solution. pollutant parameter value detection method bod5 442.7 winkler method cod 2600 reactor digestion method po4 4.31 phosver 3 (ascorbic acid) method tc 1217.7 toc analyzer tn 1039.4 toc analyzer after leachate was introduced to constructed wetland systems, moss layers had appeared in the 25% and 50% leachate fed systems within a couple of days. however, after few weeks of operations similar moss layers had appeared in the 75% and 100% leachate systems. this observation indicated that the feed concentrations in 25% and 50% cws can readily be used by primitive life forms, but higher feed concentration (75% and above) need a comparatively long period for such life forms to proliferate in harsher environmental conditions. plants in cws except cattail with 75% and 100% leachate showed a good tolerance against leachate. after about two months from initiation, cattail shoots in the 100% and 75% systems appeared to be dried and destroyed, but new shoots appeared in the 3rd month. umbrella palm shoots showed a better tolerance for leachate as the plant growth was not disturbed by the application of leachate. 3.1. evapotranspiration a significant et loss has occurred in all cws, especially in systems fed with 25% and 50% leachate (figure 1). this may be due to the evaporation which has occurred due to high air temperature and low humidity on top of increased transpiration due to the plant growth. in tropical countries a considerable amount of water evaporates from water bodies especially under warm and windy conditions. certain percentage (~ 95%) of water absorbed by the plant roots has also escaped from the small pores in leaves (transpiration). the amount of transpiration varies from plant to plant. according to the białowiec and wojnowska-baryla (2007) and headley et al. (2012) water losses through transpiration is high in macrophytes as they have inherently low efficiencies of water use. of the three plant species, the highest et rate against four different leachate loading was observed in umbrella palm plants (71.95%). evapotranspiration losses have significantly changed with the leachate concentration. the mean et losses for leachate concentrations in 25%, 50%, 75% and 100% cws were 78.04%, 69.78%, 53.27% and 41.26%, respectively. results indicated that umbrella palm containing cws with25% leachate concentrations exhibited the highest et potential. 54 figure 1: different evapotranspiration models 3.2 treatment performance all cw units performed well in the treatment of synthetic leachate, maintaining a high removal efficiency at all tested conditions. this section contains the results of the batch tests for the removal of bod5, cod, tn, tc and po4 3-. bod5 results of statistical analysis indicated that both the plant species and the leachate concentrations have significant impacts (p <0.05) on bod5 removal efficiencies. the highest mean bod5 removal efficiency was reported by umbrella palm plants for 25% leachate concentration (figure 2). cod all three plant species showed good performance in cod removal with removal efficiencies of above 70% in all testes (table 3.2). a slight decrease of removal efficiency with time was shown by 0.00 200.00 400.00 600.00 800.00 1 2 3 4 5 6 7 8 9101112 e v a p o tr a n sp ir a ti o n r a te (m l/ d ) week 100% leachate model cattail bulrush umbrella palm 0.00 200.00 400.00 600.00 800.00 1 2 3 4 5 6 7 8 9101112 e v a p o tr a n sp ir a ti o n r a te (m l/ d ) week 75% leachate model cattail bulrush umbrella palm 0.00 200.00 400.00 600.00 800.00 1 2 3 4 5 6 7 8 9 101112 e v a p o tr a n sp ir a ti o n r a te ( m l/ d ) week 50% leachate model cattail bulrush umbrella palm 0.00 200.00 400.00 600.00 800.00 1 2 3 4 5 6 7 8 9 101112 e v a p o tr a n sp ir a ti o n r a te ( m l/ d ) week 25% leachate model cattail bulrush umbrella palm meetiyagoda et al. /journal of tropical forestry and environment vol. 7, no. 02 (2017) 49-61 55 cattail and green bulrush species against 100% leachate. even though a considerable drop had occurred in the 9th week, umbrella palm exhibited the highest average removal efficiency (89.62±3.62%). figure 2: bod removal efficiencies in the presence of different plant species under different leachate loading. table 3: cod removal efficiencies in the presence of different leachate loading rate. 100% loading 75% loading 50% loading 25% loading typha angustifolia 83.06±6.16% 88.69±6.96% 96.16±1.99% 99.14±0.95% scirpus atrovirens 79.66±5.41% 85.62±5.10% 87.75±3.81% 98.24±2.08% cyperus alterufolius 89.62±3.62% 96.52±2.24% 98.73±1.20% 99.61±0.39% comparatively higher average cod removal efficiencies were observed in cws with 50% loading than cw systems with 75% and 100% leachate. in this concentration range also, the highest average removal efficiency was reported by umbrella palm. the highest cod removal efficiencies and lowest 50.00 60.00 70.00 80.00 90.00 100.00 1 2 3 4 5 6 7 8 9 10 11 12 m a ss r e m o v a l e ff ic ie n c y ( % ) week 100% leachate cattail bulrush umbrella palm 50.00 60.00 70.00 80.00 90.00 100.00 1 2 3 4 5 6 7 8 9 10 11 12 m a ss r e m o v a l e ff ic ie n c y ( % ) week 75% leachate cattail bulrush umbrella palm 50.00 60.00 70.00 80.00 90.00 100.00 1 2 3 4 5 6 7 8 9 10 11 12 m a ss r e m o v a l e ff ic ie n c y ( % ) week 50% leachate cattail bulrush umbrella palm 50.00 60.00 70.00 80.00 90.00 100.00 1 2 3 4 5 6 7 8 9 10 11 12 m a ss r e m o v a l e ff ic ie n c y ( % ) week 25% leachate cattail bulrush umbrella palm 56 variance induced by plant species was observed in cws with 25% leachate loading. all three plant species performed well at the lowest leachate concentration. total nitrogen (tn) in the presence of concentrated leachate (100%), the cws planted with cattail had shown a significantly high (p<0.05) tn removal. even though the value had dropped after the first feeding, the removal efficiency still remained at a higher level (73.54±2.45%). removal efficiency of the system with green bulrush remained stable at around 70% after the first 5 weeks. the cw with umbrella palm exhibited the highest average removal efficiency of 76.40±3.99%. performances of plant species at different leachate concentrations are given in (figure 3). figure 3: tn removal efficiencies in the presence of different plant species under different leachate loading. 50.00 60.00 70.00 80.00 90.00 100.00 1 2 3 4 5 6 7 8 9 10 11 12m a ss r e m o v a l e ff ic ie n c y ( % ) week 100% leachate cattail bulrush umbrella palm 50.00 60.00 70.00 80.00 90.00 100.00 1 2 3 4 5 6 7 8 9 10 11 12m a ss r e m o v a l e ff ic ie n c y ( % ) week 75% leachate cattail bulrush umbrella palm 50.00 60.00 70.00 80.00 90.00 100.00 1 2 3 4 5 6 7 8 9 10 11 12 m a ss r e m o v a l e ff ic ie n c y ( % ) week 25% leachate cattail bulrush umbrella palm 50.00 60.00 70.00 80.00 90.00 100.00 1 2 3 4 5 6 7 8 9 10 11 12m a ss r e m o v a l e ff ic ie n c y ( % ) week 50% leachate cattail bulrush umbrella palm meetiyagoda et al. /journal of tropical forestry and environment vol. 7, no. 02 (2017) 49-61 57 for both cattail and green bulrush, the tn removal efficiencies exhibited almost constant values, regardless of the leachate loading. the cw with umbrella palm showed the highest average tn removal efficiency among the 12 tested twelve models, regardless of leachate loading. the highest removal efficiency was observed in cws at 25% leachate loading (97.34%). the plant species and the loading strength of leachate showed a significant (p<0.05) impact on tn removal. the interaction between tn removal, plant species and loading strength was also significant (p < 0.05). total carbon (tc) in cws, the organic carbon is converted to co2 or ch4 by microbial degradation and is absorbed by plants for cell synthesis. carbon removal is major function of cws. therefore tc removal efficiency by different plant species was also studied. slight decrease of tc removal efficiency with time was observed in all treatment systems which is attributed to initial adsorption by the materials in cws. models planted with green bulrush showed the poorest tc removal efficiencies ranging from 67.97% to 82.83%. the highest removal efficiencies (88.72-97.34%) were exhibited by cws planted with umbrella palm. the cw planted with umbrella palm and fed with 25% leachate showed the highest average tc removal efficiency at 97.34±1.40%. the p-value of less than 0.05 indicates that significant differences exist in tc removal efficiencies in the cws with different plant species and different leachate loadings (figure 4). phosphate (po4 3-) in cws, po4 3may be removed by plant uptake; therefore the type of plant species may have a great influence on po4 3-removal.all three systems showed a high po4 3-removal capacity of above 88%. the highest po4 3-removal efficiencies (96.16-98.45%) were observed in umbrella palm planted models, regardless of the leachate concentration, while green bulrush exhibited the lowest performance (88.7094.41%). the highest average removal efficiency was registered by umbrella palm at 25% leachate concentration. as the p-values of plant species, leachate concentrations and interactions are less than 0.05, it can be concluded that significant differences in po4 3removal efficiencies are existing among those parameters (figure 5). 3.3 effluent standard to find out the optimal concentration of leachate to be fed to cws, the effluent cod and bod5 values of each system were compared with the central environmental authority (cea) discharge standards (gazette no. 1534/18, 2008). the cea effluent discharge standards for cod and bod5 are 250 mg/l and30 mg/l, respectively. it was observed that both standards were satisfactorily achieved in cws planted with umbrella palm and fed with 25% and 50% leachate concentrations. but cws with other plant species were capable of achieving the cod and bod5permissible discharge levels only in systems fed with 25% leachate concentration. 58 50.00 60.00 70.00 80.00 90.00 100.00 1 2 3 4 5 6 7 8 9 10 11 12 m a ss r e m o v a l e ff ic ie n c y ( % ) week 50% leachate cattail bulrush umbrella palm figure 4: tc removal efficiencies in the presence of different plant species under different leachate loading. 50.00 60.00 70.00 80.00 90.00 100.00 1 2 3 4 5 6 7 8 9 10 11 12 m a ss r e m o v a l e ff ic ie n c y ( % ) week 100% leachate cattail bulrush umbrella palm 50.00 60.00 70.00 80.00 90.00 100.00 1 2 3 4 5 6 7 8 9 10 11 12 m a ss r e m o v a l e ff ic ie n c y ( % ) week 75% leachate cattail bulrush umbrella palm 50.00 60.00 70.00 80.00 90.00 100.00 1 2 3 4 5 6 7 8 9 10 11 12m a ss r e m o v a l e ff ic ie n c y ( % ) week 25% leachate cattail bulrush umbrella palm meetiyagoda et al. /journal of tropical forestry and environment vol. 7, no. 02 (2017) 49-61 59 50.00 60.00 70.00 80.00 90.00 100.00 1 2 3 4 5 6 7 8 9 10 11 12 m a ss r e m o v a l e ff ic ie n c y ( % ) week 75% leachate cattail bulrush umbrella palm figure 5: po4 3removal efficiencies in the presence of different plant species under different leachate loading. 4. conclusions twelve (12) identical ssf cw models were planted with 3 plant species and fed with 4 different leachate concentrations. stock synthetic leachate solution was prepared and diluted to 4 concentrations (25%, 50%, 75% and 100%) as the feed solutions. pollutant (cod, bod5, tn, tc and po4 3-) removal efficiencies obtained from several batch tests were subjected to two-way anova analysis and statistical differences among systems were assessed. the mean comparisons were performed using basic statistical 50.00 60.00 70.00 80.00 90.00 100.00 1 2 3 4 5 6 7 8 9 10 11 12 m a ss r e m o v a l e ff ic ie n c y ( % ) week 100% leachate cattail bulrush umbrella palm 50.00 60.00 70.00 80.00 90.00 100.00 1 2 3 4 5 6 7 8 9 10 11 12 m a ss r e m o v a l e ff ic ie n c y ( % ) week 50% leachate cattail bulrush umbrella palm 50.00 60.00 70.00 80.00 90.00 100.00 1 2 3 4 5 6 7 8 9 10 11 12 m a ss r e m o v a l e ff ic ie n c y ( % ) week 25% leachate cattail bulrush umbrella palm 60 analysis to find out the best plant species and best feed concentration. effluent concentrations were compared against permissible discharge standards. fluctuations in removal efficiencies were observed in all tested models, which is normal in any living biological system. all 3 plant species performed satisfactorily well for leachate concentrations of 25% according to the cea permissible discharge standards. the highest average pollutant removal efficiencies were observed in cws planted with umbrella palm (cyperus alterufolius) for all leachate concentrations. the result of two way anova tests indicated that a significant difference exists among the three plant species and four feed concentrations in removing all tested pollutant parameters. therefore, mean comparisons were performed to find out the plant species and concentrations corresponding to the best treatment. umbrella palm exhibited the best removal efficiencies for all parameters irrespective of leachate concentration. the results gained from two-way anova comparing the performance of the plant species independent of leachate concentration also proved that the same plant species is significantly efficient, in treatment of leachate. mean comparisons were performed using minitab software to find the concentration corresponding to the best treatment efficiency irrespective of the plant species. the best removal efficiencies in removing bod, cod and tn were given by 25% leachate, while 50% leachate has been given the best removal efficiency of tc and po4 3-. evapotranspiration studies recorded a significantly higher loss for all plant species at all leachate concentrations. this was attributed to the tropical climate conditions of the study location. the significant differences among the et potential for different plant species were observed. evapotranspiration rates were also significantly changed with the leachate concentration. the highest et loss rate was reported in cws containing umbrella palm plants and fed with 25% leachate. references abira, m.a., ngirigacha, h.w. and van bruggen, j.j.a., 2003. preliminary investigation of the potential of four tropical emergent macrophytes for treatment of pre-treated pulp and papermill wastewater in kenya. water science and technology, 48(5), pp.223-231. akinbile, c.o., yusoff, m.s. and zuki, a.a., 2012. landfill leachate treatment using sub-surface flow constructed wetland by cyperushaspan. waste management, 32(7), pp.1387-1393. allen, w.c., hook, p.b., biederman, j.a. and stein, o.r., 2002. temperature and wetland plant species effects on wastewater treatment and root zone oxidation. journal of environmental quality, 31(3), pp.1010-1016. brix, h., 1997. do macrophytes play a role in constructed treatment wetlands?. water science and technology, 35(5), pp.11-17. cothren, g.m., chen, s. and pardue, j.h., 2002. investigation of subsurface flow constructed wetland designs. public works management & policy, 7(1), pp.32-45. gazzatte no. 1534/18. 2008. schedule itolerance limits for the discharge of industrial waste into inland surface waters, the gazette of the democratic socialist republic of sri lanka. justin, m.z. and zupančič, m., 2009. combined purification and reuse of landfill leachate by constructed wetland and irrigation of grass and willows. desalination, 246(1-3), pp.157-168. kadlec, r.h. and knight, r.l., 1996. treatment wetlands. crc. baca raton, fl. kietlińska, a. and renman, g., 2005. an evaluation of reactive filter media for treating landfill leachate. chemosphere, 61(7), pp.933-940. meetiyagoda et al. /journal of tropical forestry and environment vol. 7, no. 02 (2017) 49-61 61 kulikowska, d. and klimiuk, e., 2008. the effect of landfill age on municipal leachate composition. bioresource technology, 99(13), pp.5981-5985. lavrova, s. and koumanova, b., 2010. influence of recirculation in a lab-scale vertical flow constructed wetland on the treatment efficiency of landfill leachate. bioresource technology, 101(6), pp.17561761. lin, x., lan, c. and shu, w., 2003, october. treatment of landfill leachate by subsurface-flow constructed wetland: a microcosm test. in proceedings of the third international conference on vetiver and exhibition: vetiver and water. guangzhou, china (pp. 216-223). lin, y.f., jing, s.r., wang, t.w. and lee, d.y., 2002. effects of macrophytes and external carbon sources on nitrate removal from groundwater in constructed wetlands. environmental pollution, 119(3), pp.413-420. mander, ü.,teiter, s., kuusemets, v., lohmus, k., öövel, m., nurk, k. and augustin, j., 2003. nitrogen and phosphorus budgets in a subsurface flow wastewater treatment wetland. wit transactions on ecology and the environment, 61. naylor, s., brisson, j., labelle, m.a., drizo, a. and comeau, y., 2003. treatment of freshwater fish farm effluent using constructed wetlands: the role of plants and substrate. water science and technology, 48(5), pp.215-222. pendleton, c.h., morris, j.w.f., goldemund, h., rozema, l.r., mallamo, m. and agricola, s.l., 2005. leachate treatment using vertical subsurface flow wetland systems–findings from two pilot studies. in r. cossu and r. stegmann eds., 10th international waste management and landfill symposium, environmental sanitary engineering centre (pp. 727-728). sawaittayothin, v. and polprasert, c., 2007. nitrogen mass balance and microbial analysis of constructed wetlands treating municipal landfill leachate. bioresource technology, 98(3), pp.565-570. sawaittayothin, v. and polprasert, c., 2007. nitrogen mass balance and microbial analysis of constructed wetlands treating municipal landfill leachate. bioresource technology, 98(3), pp.565-570. stottmeister, u., wießner, a., kuschk, p., kappelmeyer, u., kästner, m., bederski, o., müller, r.a. and moormann, h., 2003. effects of plants and microorganisms in constructed wetlands for wastewater treatment. biotechnology advances, 22(1), pp.93-117. tanner, c.c., 1996. plants for constructed wetland treatment systems—a comparison of the growth and nutrient uptake of eight emergent species. ecological engineering, 7(1), pp.59-83. tyrrel, s.f., leeds-harrison, p.b. and harrison, k.s., 2002. removal of ammoniacal nitrogen from landfill leachate by irrigation onto vegetated treatment planes. water research, 36(1), pp.291-299. verhoeven, j.t., arheimer, b., yin, c. and hefting, m.m., 2006. regional and global concerns over wetlands and water quality. trends in ecology & evolution, 21(2), pp.96-103. wojciechowska, e., gajewska, m. and obarska-pempkowiak, h., 2010. treatment of landfill leachate by constructed wetlands: three case studies. polish journal of environmental studies, 19(3), pp.643650. yalcuk, a. and ugurlu, a., 2009. comparison of horizontal and vertical constructed wetland systems for landfill leachate treatment. bioresource technology, 100(9), pp.2521-2526. this study is focused on the investigation of three different types of plant species namely; narrow leaf cattail (typha angustifolia), green bulrush (scirpus atrovirens) and umbrella palm (cyperus alternifolius) for treatment of leachate. twelve labor... 2. materials and method 2.1 plant species 2.2 experimental design 2.3 synthetic leachate 2.4 leachate loading 2.5 evapotranspiration (et) loss 2.6statistical analysis issn 2235-9370 print / issn 2235-9362 online © university of sri jayewardenepura issn 2235-9370 print / issn 2235-9362 online ©2017 university of sri jayewardenepura issn 2235-9370 print / issn 2235-9362 online ©2017 university of sri jayewardenepura (1) issn 2235-9370 print / issn 2235-9362 online ©2017 university of sri jayewardenepura (2) abhayawardhana et al. /journal of tropical forestry and environment vol. 9, no. 02 (2019) 65-77 _____________________________________________ *correspondence: dnudilini@gmail.com issn 2235-9370 print/issn 2235-9362 online © university of sri jayewardenepura 65 removal of heavy metals and nutrients from municipal wastewater using salvinia molesta and lemna gibba m.l.d.d. abhayawardhana1*, n.j.g.j. bandara1 and s.k.l.s. rupasinghe2 1department of forestry and environmental science, university of sri jayewardenepura, sri lanka 2national water supply and drainage board, ratmalana date received: 26-03-2019 date accepted: 12-12-2019 abstract the present study was focused on the investigation of the abilities and efficiencies of salvinia molesta and lemna gibba to remove selected heavy metals (cr, cu, fe, ni and pb) and excess nutrients from wastewater taken from the moratuwa-ratmalana municipal wastewater treatment plant. the wastewater samples were analysed for ph, temperature, for n-nitrates, n-nitrites, ammonia nitrogen, phosphates, and selected heavy metals, biochemical oxygen demand (bod), chemical oxygen demand (cod) and total kjeldhal nitrogen. then, the wastewater samples were treated with s. molesta and l. gibba separately for a period of 7 days and analysed for n-nitrates, n-nitrites, ammonia nitrogen, phosphates and five selected heavy metals at 24 hour intervals. bod, cod and total kjeldhal nitrogen were analysed at 7 days intervals. the average total nitrogen removal efficiencies of s. molesta and l. gibba were 73.3% and 62.1% whereas the average total phosphate removal efficiencies of s. molesta and l. gibba were 72.6% and 77.2% respectively. the average cr, cu, fe, ni and pb removal efficiencies of s. molesta were 81.6%, 69.8%, 65.2%, 66.3% and 74.8% respectively. the average cr, cu, fe, ni and pb removal efficiencies shown by l. gibba were 86.9%, 69.7%, 73.1%, 61.8% and 85.7% respectively. the bio concentration factors of s. molesta for cr, cu, fe, pb and ni were 823, 698, 652, 663 and 748 respectively and the bio concentration factors of s. molesta for cr, cu, fe, pb and ni were 870, 698, 731, 618 and 857 respectively. according to the obtained results in the present study s. molesta and l. gibba can be considered as suitable candidates for the polishing of municipal wastewater. keywords: heavy metals, lemna gibba, nutrients, salvinia molesta 1. introduction wastewater contains biodegradable organics, nutrients; mainly nitrogen and phosphate compounds that lead to eutrophication, organic pollutants, heavy metals and dissolved inorganics such as sodium, calcium and sulphates etc. almost all the human activities generate wastewater. nature has an assimilation capacity to cope with small amounts of wastewater and pollution associated with it, but nature has no capacity to handle the huge amount of wastewater that is generated every day after being subjected to human consumption and several other uses. therefore, the treatment of this water and returning clean and safe water into the waterways is essential to ensure the safety of people and the environment. the proper treatment of wastewater is an environmental challenge since the wastewater is required to be treated and disposed safely in an efficient manner. further, the presence of some components in the water poses a challenge in the wastewater treatment process. doi: https://doi.org/10.31357/jtfe.v9i2.4469 66 enrichment of large quantities of nitrogen and phosphate compounds in wastewater is one of the main causes of eutrophication that negatively affects many natural water bodies. heavy metals are considered as priority pollutants due to their acute toxicity. heavy metals in wastewater cause detrimental effects on environment and human health. the heavy metals in wastewater have the potential of bioaccumulation which can cause adverse impacts on environment and human health. phytoremediation is the use of both aquatic and terrestrial plants for the treatment of contaminated water and soils (ali et al., 2013). according to previous studies, some aquatic macrophytes have shown a great promise in wastewater treatment, both in the removal of nutrients (phosphates, nitrogen compounds) and heavy metals. s. molesta and l. gibba are two preferable candidates which had been used for the treatment of wastewater in previous studies. low cost and easy maintenance make the aquatic plant system preferable to use. in an aqueous solution, metals are available in soluble form. therefore, the accumulation by the aquatic plants can be achieved much more easily and more efficiently than using terrestrial plants. s. molesta is a free floating aquatic plant which spreads rapidly by vegetative reproduction. the species is well-known for its phytoremediation potential (koutika and rainey, 2015). l. gibba is a rooted free-floating aquatic plant consisting of small fronds. due to the high growth rate and large potential for the uptake of heavy metals and nutrients, members of genus lemna have appeared as suitable candidates for the phytoremediation of heavy metal contaminated wastewater (verma and suthar, 2015). according to previous studies, the influent of moratuwa-ratmalana wastewater treatment plant contains total nitrogen and total phosphates higher than the upper limits given in the standards. the presence of several heavy metals i.e. cu, cr, pb, fe, and ni is also recorded (danushika et al., 2017). since the sludge disposed by the treatment plant constitutes of heavy metals, the final disposal of sludge has posed problematic issues. the study is carried out to determine the efficiency of s. molesta and l. gibba as candidates for polishing of the influent of moratuwa-ratmalana wastewater treatment plant. the potential of using s. molesta and l. gibba for the removal of nutrients (nitrogen compounds, phosphates) and selected heavy metals (cr, cu, ni, pb, fe) is determined in the study, thus investigating the capability of these two aquatic macrophytes to be used for the treatment of municipal wastewater. 2. methodology 2.1 plant acquisition and acclimatisation s. molesta was collected from a fresh water body near the university. l. gibba was collected from moratuwa-ratmalana wastewater treatment plant. healthy mature plants were selected for the experiment and rinsed with tap water in order to remove adhering mud particles or epiphytes. the plants were left for an adaptation period of 10 days, growing in the containers inside the green house of department of forestry and environmental science, university of sri jayewardenepura to be adapted for the experimental conditions. 2.2 sample collection wastewater samples were collected from the inlet of the moratuwa-ratmalana wastewater treatment plant. samples were collected weekly. after the collection, the samples were checked for ph, temperature, biochemical oxygen demand (bod), chemical oxygen demand (cod), nitrates, nitrites, ammonia nitrogen, phosphates and total kjeldhal nitrogen and heavy metals (cr, cd, cu, mn, pb, ni, and fe). the ph was measured using the ph meter and the temperature was measured using a thermometer at the time of sample collection. bod was measured using winkler method. cod was determined using closed reflux method. ammonia nitrogen was measured by comparative ammonia method. total kjeldhal nitrogen concentration was measured by micro kjeldhal method. the concentrations of nitrates, nitrites and phosphates were measured using hach 890 meter by powder pillow method. the abhayawardhana et al. /journal of tropical forestry and environment vol. 9, no. 02 (2019) 65-77 67 concentrations of the heavy metals were measured by atomic absorption spectroscopy (aas) method. the wastewater samples were collected in polypropylene bottles and were transferred to the green house immediately. 2.3 experimental design eight rectangular shaped glass aquariums with the dimensions of 1 ̍×6 ̎×6 ̎ were used to perform the experiment. six containers were taken and 3l of collected wastewater was added to each tank. to three tanks, 15 g of s. molesta was introduced. to other three tanks, 15 g of l. gibba was introduced. the other two tanks were filled with distilled water. 15 g of s. molesta was added to one tank and 15 g of l. gibba was added to the other tank. these two tanks with distilled water were used as control samples in order to compare the relative growth of the plants in wastewater and the control samples. each experiment was carried out for 7 days. 40 ml of wastewater samples were withdrawn from each tank at 24 hour intervals. the seven day experiment was repeated for six times. 2.4 sample analysis the samples withdrawn from the tanks at 24 hour intervals were checked for ph, temperature, nitrates, nitrites, ammonia nitrogen and phosphates. the collected water samples were filtered using whatmann no.1 filter papers and were analysed using atomic absorption spectroscopy (aas) method to determine cr, cu, pb, ni and fe concentrations at 24 hour intervals. at the end of the experiment, on the 7th day, the samples were checked for bod, cod and total kjeldhal nitrogen. 2.5 analysis of plant materials on the 7th day, plant materials were harvested and their fresh weights were determined. then the plant materials were oven dried at 800° c for 48 hours and the dry weights were determined. then the dried biomass was digested according to dry digestion method (kalagbor and opusunju, 2015) and were analysed for concentrations of cr, cu, pb, ni, and fe using atomic absorption spectroscopy. 2.6 calculations the following parameters were calculated using the mean values of the data obtained through the experiments. relative growth relative growth values were calculated for s. molesta and l. gibba using the initial fresh weight and final fresh weight values. relative growth= final fresh weight (g) initial fresh weight (g) (thayaparan et al., 2013) removal efficiency the removal efficiencies for total nitrogen, total phosphates, cod, bod and selected heavy metals by s. molesta and l. gibba were calculated using initial and final values. removal efficiency = initial concentration -final concentration initial concentration ×100 metal uptake capacity the uptake capacities for each metal for s. molesta and l. gibba were calculated. metal uptake capacity (mg/kg)= metal concentration of the dried biomass ( mg l ) ×total diluted volume(ml) dry weight (g) (1) (2) (3) 68 (lokuge, 2016) bio concentration factor (bcf) the bio concentration factors for each metal for s. molesta and l. gibba were calculated. bcf= metal concentration of the dried biomass ( mg kg ) initial concentration of the metal in external solution ( mg l ) (uysal, 2013) 2.7 statistical analysis the data were statistically analysed using minitab 18 software. the significant differences among the parameters were determined by one-way anova test. the treatment means were compared using tukey’s 95% simultaneous confidence intervals test. 3. results and discussion 3.1 nutrient removal by s. molesta and l. gibba total nitrogen in the present study, the final total nitrogen concentrations in the tanks with s. molesta and l. gibba were 31.82 mg l-1 and 51.81 mg l-1 respectively, whereas the initial total nitrogen concentration was 136.27 mg l-1 s. molesta showed a significantly higher potential (p<0.05) in the uptake of total nitrogen than l. gibba in the present study. figure 1. the mean values of initial and final concentrations of total nitrogen in the tank with s. molesta and in the tank with l. gibba. bars indicate mean±sd (standard deviation), where n=6. according to ng and chan (2017), the nitrate concentration in palm oil mill effluent treated by s. molesta has increased until day 12 and then has slightly decreased in the end. in a free floating system, the total nitrate concentration is controlled by nitrification and denitrification, in addition to plant and microbial uptake. in the present study also, the nitrate concentration of the tank with s. molesta had remained constant from day 3 to day 4. the nitrate concentration in l. gibba had increased slightly from day 3 to day 4. these are due to the increase of nitrates as a result of nitrification. however, in the present study, the increase of nitrates by nitrification is not much high. nitrification/ denitrification can be caused by nitrifying bacteria which are attached to flocculates (korner and vermaat, 1998). but, the flocculates settled to the bottom of the tanks due to the small depth of the tanks. therefore, the nitrification/ denitrification by suspended bacteria can be neglected. 0 20 40 60 80 100 120 140 160 initial l.gibba s.molesta t o ta l n it ro g e n c o n c e n tr a ti o n ( m g /l ) sample (4) abhayawardhana et al. /journal of tropical forestry and environment vol. 9, no. 02 (2019) 65-77 69 in the present study, volatilisation of ammonium ions as ammonia gas can be neglected since the surface of the tank is covered with the dense mat of plant materials. also, the ph value of the wastewater had remained close to neutral values throughout the experiment. therefore, only a small amount of ammonium ion may be present as ammonia gas. the concentrations of nitrites, nitrates, ammonia nitrogen and phosphates in the tank with s. molesta had decreased daily in the seven day period. the total nitrate concentration did not show a gradual decrease. the concentration of nitrates had remained constant from day 3 to day 4. the concentrations of nitrites, nitrates, ammonia nitrogen and phosphates in the tank with l. gibba had decreased in the period of 7 days. the concentration of nitrates has shown a slight increase from day 3 to day 4. figure 2. the daily variation of the mean values of concentrations of nitrites, nitrates, ammonia nitrogen and phosphates in the tank with s.molesta where n=6. the total nitrogen removal efficiencies of s. molesta and l. gibba were 73.35% and 62.18% respectively. s. molesta has shown a significantly greater (p<0.05) efficiency in the removal of total nitrogen than l. gibba. according to žaltauskaitė et al., (2014), the efficiency of l. gibba in the removal of nitrogen from wastewater is between 42%-62% of total nitrogen, depending on initial nitrogen concentrations. the present study has also shown similar results. according to mkandawire and dudel, (2005), the total nitrogen removal efficiency by lemna spp. is 50%. in the present study, l. gibba has demonstrated an efficiency higher than that. 3.1.2 total phosphate phosphorous is an essential macronutrient for plants which is required for the synthesis of adenosine diphosphate (adp), adenosine triphosphate (atp) and nucleic acids. therefore, free orthophosphates are specifically absorbed from wastewater by plant systems. in the present study, the initial concentrations of total phosphates in the tanks with s. molesta and l. gibba were 1.65 mg l-1 and 1.5 mg l-1 respectively, whereas the initial concentration was 6.17 mg/l . the final total phosphate concentrations in the two tanks were not significantly different (p>0.05). 0 5 10 15 20 25 30 35 40 0 1 2 3 4 5 6 7 8 c o n c e n tr a ti o n ( m g /l ) sampling interval (days)nitrate nitrite ammonia n phosphate 70 figure 3. the daily variation of the mean values of concentrations of nitrites, nitrates, ammonia nitrogen and phosphates in the tank with l. gibba where n=6. figure 4. the mean values of initial and final concentrations of total phosphate in the tank with s. molesta and in the tank with l. gibba. bars indicate mean±sd, where n=6. mohedano et al., (2012) showed a final total phosphate concentration of 5.2 mg l-1 on day seven, whereas the initial concentration was 215 mg l-1 in which the swine waste was treated by l. gibba. in this study, the effluent has been sent through a system consisting of a storage pond and two duckweed ponds. therefore, the removal potential is higher than the present study as the effluent has gone through the duckweed pond twice in a single treatment and because of the increased surface area for the treatment. the total phosphate removal efficiencies of s. molesta and l. gibba were 72.63% and 77.29% respectively which were not significantly different (p>0.05). according to žaltauskaitė et al., (2014), the total phosphate removal efficiency from municipal wastewater by l. minor is 100%. however, mkandawire and dudel, (2005) shows that the efficiency of total phosphate removal by lemna spp. is between 50-60%. in the present study, l. gibba has demonstrated a greater efficiency than that. bod and cod the mean initial bod value was 259.22 mg l-1 whereas the mean final bod values in the tank with s. molesta and in the tank with l. gibba were 73.75 mg l-1 and 85.29 mg l-1 respectively which were not significantly different (p>0.05). the mean initial cod value was 530.19 mg/l whereas the mean final 0 5 10 15 20 25 30 35 40 0 1 2 3 4 5 6 7 8 c o n c e n tr a ti o n ( m g /l ) sampling interval (days)nitrate nitrite 0 1 2 3 4 5 6 7 8 9 initial l.gibba s.molesta t o ta l p h o sp h a te s c o n c e n tr a ti o n ( m g /l ) sample abhayawardhana et al. /journal of tropical forestry and environment vol. 9, no. 02 (2019) 65-77 71 cod values in the tank with s. molesta and in the tank with l. gibba were 200.80 mg l-1 and 111.89 mg l1 respectively which were significantly different (p<0.05). the cod reduction potential demonstrated by l. gibba was higher than in that of s. molesta in the present study. in the present study, the bod removal efficiencies of s. molesta and l. gibba were 71.51% and 67.24% respectively which were not significantly different (p>0.05). the cod removal efficiencies of s. molesta and l. gibba were 61.985% and 78.957% respectively. l.gibba demonstrated a significantly higher efficiency (p<0.05) in the removal of cod. according to mkandawire and dudel (2005), the bod removal efficiency and cod removal efficiency of lemna spp. are 60% and 30-40% respectively. but, in the present study, l. gibba has shown greater efficiencies than that in the removal of both bod and cod. kumari and tripathi (2014) reports bod and cod removal efficiencies by mixed culture of eichhornia crassipes and salvinia natans accompanied by aeration in municipal wastewater as 84.5% and 83.2% respectively. the efficiencies are greater than the bod and cod removal efficiencies of s. molesta and l. gibba recorded in the present study. the effect of aeration and the enhancement of removal caused by the use of mixed culture of eichhornia crassipes and salvinia natans can be the reasons for higher efficiencies. figure 5. the mean values of initial and final values of bod in the tank with s. molesta and in the tank with l. gibba. bars indicate mean ± sd, where n= 6. figure 6. the mean values of initial and final values of cod in the tanks with s. molesta and l. gibba. bars indicate mean±sd, where n=6. 0 50 100 150 200 250 300 initial l.gibba s.molesta b io c h e m ic a l o x y g e n d e m a n d ( m g /l ) sample 0 100 200 300 400 500 600 initial l.gibba s.molesta c h e m ic a l o x y g e n d e m a n d ( m g /l ) sample 72 3.2 heavy metal removal by salvinia molesta and lemna gibba chromium (cr) the final cr concentrations of the two tanks were not significantly different (p>0.05). the cr uptake capacity of l. gibba was significantly greater (p<0.05) than that of s. molesta. the bio concentration factor (bcf) of s. molesta and l. gibba were not significantly different (p>0.05) and both were lower than 1,000. the initial cr concentration was higher than tolerance limits for industrial and domestic wastewater discharged into marine coastal areas (1 mg l-1). the final concentrations of cr in both tanks were lower than the tolerance limit. but, toxicity symptoms were not observed in the harvested plant materials. table 1: the mean values of initial cr concentration in wastewater samples, final cr concentration after being subjected to the treatment by plants, the metal uptake capacities of the two species and the bio concentration factors (bcf). characteristic control salvinia molesta control lemna gibba salvinia molesta lemna gibba initial concentration (mg l-1) 1.58±0.08 a1 1.58±0.08 a1 final concentration (mg l-1) 0.29±0.07 b1 0.21±0.05 b1 metal uptake capacity (mg kg -1 ) 64.32±2.44 b2 68.55±2.64 a2 bcf 823.2±40.78 a3 870.0±28.25 a3 the significant differences are indicated by superscripted letters. the cr removal efficiencies of s. molesta and l. gibba are 81.66% and 86.99% respectively, which were significantly different (p<0.05). l. gibba demonstrated a higher cr removal efficiency than s. molesta in the present study. copper (cu) the final cu concentrations of the two tanks were not significantly different (p >0.05). in addition, the cu uptake capacities of s. molesta and l. gibba were not significantly different (p>0.05). the bcf values of the two plants for cu were not significantly different (p>0.05) and the values were lower than 1000. the cu removal efficiencies of s.molesta and l.gibba were 69.81% and 69.78% respectively. the efficiencies were not significantly different (p>0.05). table 2: the mean values of initial cu concentration in wastewater samples, final cu concentration after being subjected to the treatment by plants, the metal uptake capacities of the two species and the bio concentration factors (bcf). characteristic control salvinia molesta control lemna gibba salvinia molesta lemna gibba initial concentration (mg l -1 ) 0.302±0.13 a1 0.302±0.13 a1 final concentration (mg l -1 ) 0.097±0.07 b1 0.094±0.05 b1 metal uptake capacity (mg kg -1 ) 10.283±3.78 a2 10.408±4.14 a2 bcf 698.029±72.86 a3 698.421±64.80 a3 the significant differences are indicated by superscripted letters. iron (fe) abhayawardhana et al. /journal of tropical forestry and environment vol. 9, no. 02 (2019) 65-77 73 the final fe concentrations of the two tanks were not significantly different (p >0.05). the fe uptake capacities of s. molesta and l. gibba were not significantly different (p>0.05). in addition, the bcf values of the two plants for fe were not significantly different (p>0.05) and the values were lower than 1000. the fe removal efficiencies of s. molesta and l. gibba were 65.27% and 73.10% respectively. the efficiencies were not significantly different (p>0.05). nickel (ni) the final ni concentrations in both tanks were not significantly different (p>0.05). the ni uptake capacities of s.molesta and l.gibba were not significantly different (p>0.05). the bcf values of the two plants for ni were not significantly different (p>0.05) and the values were lower than 1000. table 3: the mean values of initial fe concentration in wastewater samples, final fe concentration after being subjected to the treatment by plants, the metal uptake capacities of the two species and the bio concentration factors (bcf). characteristic control salvinia molesta control lemna gibba salvinia molesta lemna gibba initial concentration (mg l-1) 0.124±0.02a1 0.124±0.02a1 final concentration (mg l-1) 0.044±0.01b1 0.036±0.02b1 metal uptake capacity (mg kg-1) 4.008±1.79a2 4.408±1.74a2 bcf 652.7±53.71a3 731.0±120.16a3 the significant differences are indicated by superscripted letters. the ni removal efficiencies of s. molesta and l. gibba were 66.39% and 61.87% respectively. the efficiencies were not significantly different (p>0.05). table 4: the mean values of initial ni concentration in wastewater samples, final ni concentration after being subjected to the treatment by plants, the metal uptake capacities of the two species and the bio concentration factors (bcf). the significant differences are indicated by superscripted letters. lead (pb) the final pb concentrations of the two tanks were not significantly different (p>0.05). the pb uptake capacities of s. molesta and l. gibba were not significantly different (p>0.05). the bcf values were lower than 1000 and the bcf value of l. gibba was significantly higher (p<0.05) than that of s. molesta. the pb removal efficiencies of s. molesta and l. gibba were 74.85% and 85.74% respectively. the pb removal efficiency by l. gibba was significantly higher (p<0.05) than that of s. molesta. characteristic control salvinia molesta control lemna gibba salvinia molesta lemna gibba initial concentration (mg l-1) 0.217±0.04a1 0.217±0.04a1 final concentration (mg l-1) 0.072±0.01b1 0.081±0.01b1 metal uptake capacity (mg kg-1) 7.258±1.79a2 6.783±1.74a2 bcf 663.9±69.63a3 618.7±51.32a3 74 table 5: the mean values of initial pb concentration in wastewater samples, final pb concentration after being subjected to the treatment by plants, the metal uptake capacities of the two species and the bio concentration factors (bcf). control salvinia molesta control lemna gibba salvinia molesta lemna gibba initial concentration (mg l-1) 0.292±0.07a1 0.292±0.07a1 final concentration (mg l-1) 0.073±0.02b1 0.043±0.01b1 metal uptake capacity (mg kg-1) 10.917±2.83a2 12.45±3.05a2 bcf 749.0±34.78b3 857.4±26.61a3 the significant differences are indicated by superscripted letters. according to al-khafaji et al. (2017) the cr, ni and pb removal efficiencies of lemna minor are 32.26%, 74.48%, and 79.1% respectively. however, in the present study, l.gibba has reported higher efficiencies for the removal of cr and pb and lower efficiency for the removal of ni. according to verma and suthar (2015), pb removal efficiency of l.gibba at ph 7 and 2 mg l-1 pb concentrations is 93.8% which is higher than the present study. dhir and srivastava (2011) report cu, ni and cr removal efficiencies in a multi-metal solution by salvinia natans respectively as 73.8%, 56.8%, and 41.4%. in the present study, s.molesta has shown higher efficiencies for the removal of ni and cr and lower efficiencies for the removal of cu. bio concentration factor (bcf) bio concentration factor (bcf) is an index that provides information about the potential of the plants for the uptake of heavy metals. if the bcf value exceeds 1,000, the particular plant can be considered as a useful candidate for the uptake of heavy metals (zayed et al. (1998). in the present study, none of the bcf values exceeded 1,000. according to thayaparan et al. (2013), the bcf values of azolla pinnata for pb had increased with the increase in the initial pb concentration and the bcf value is higher than 1,000 when the initial pb concentration exceeds 4 mg l-1. lokuge (2016) reports a reduction in bcfs of cr, cd, ni and pb when they were presented in altogether. according to the author, the competition of the metals for the uptake sites and the interactive effects of the metals are the reasons for the reduction of the bcf values. according to ranjitha et al. (2016), s. molesta has shown its potential in the uptake of cu, cr, pb and cd and any change in growth regulation is not observed. according to the observations of the present study also, s. molesta and l. gibba had grown healthily with the accumulation of these heavy metals. toxicity symptoms caused by heavy metals were not observed in the harvested plant materials. however, the tolerance limits of the plants for the heavy metals are not discovered. zayed et al. (1998) reports the bcf values of duckweeds as 500 to 800 for cu, 400 to 700 for cr, and 50 to 450 for pb at low supply concentrations (1 mg l-1). in the present study, similar bcf values are recorded for cu, but higher bcf values are recorded for pb and cr. 3.3 plant material analysis the relative growth values of the two control samples were not significantly different (p>0.05). the relative growth values of s. molesta and l. gibba were significantly different (p<0.05). the relative growth value of s. molesta was the highest. the relative growth value of l. gibba was the second highest. the relative growth values of both control samples were lower than the s .molesta and l. gibba samples. the dry weights of the two control samples were not significantly different (p>0.05) and the dry weights of s. molesta and l. gibba were not significantly different (p>0.05). the fresh weights of s. molesta and l. gibba were significantly different (p<0.05). the dry weights of the two control samples abhayawardhana et al. /journal of tropical forestry and environment vol. 9, no. 02 (2019) 65-77 75 were not significantly different (p>0.05). the final fresh weight of s. molesta plants was the highest because of its high moisture content. however, the dry weight of s. molesta was lower than the dry weight of l. gibba. table 6: the mean final fresh weights, mean relative growth values and the mean dry weights obtained from the tank with salvinia molesta, the tank with lemna gibba, the control tank with salvinia molesta and the control tank with lemna gibba. control salvinia molesta control lemna gibba salvinia molesta lemna gibba fresh weight (g) 17.828±2.16c1 16.479±1.37c1 34.918±3.67a1 24.197±3.67b1 relative growth 1.188±0.14c2 1.099±0.09c2 2.191±0.37a2 1.613±0.24b2 dry weight (g) 0.536±0.20b3 0.543±0.12b3 1.091±0.19a3 1.135±0.35a3 n=6. the significant differences are indicated by superscripted letters. in the control sample, distilled water was used as the substrate for the plant growth. at the end of the experiment, on the 7th day, a brown coloration in leaves was observed in the control sample of s. molesta. but, s. molesta plants grown in the wastewater tank did not show a discoloration. the most likely reason for the brown colour observed in the control sample of s. molesta is the lack of nutrients. however, in the control sample of l. gibba, no discoloration was observed. the l. gibba plants showed an increase in growth even in the control sample as well as in the wastewater sample. therefore, the potential of l. gibba species to survive in adverse conditions can be identified. according to zayed et al. (1998), growth reduction of duckweeds is reported only at 10 mg l-1 ni concentration. also, ranjitha et al. (2016) reports that there is no change in the growth rate of s. molesta when exposed to cr, cu, cd and pb containing wastewater where the particular heavy metals were present in concentrations lower than 2.5 mg l-1. therefore in the present study, the low concentration of heavy metals may be the reason for the absence of growth reduction in the plants grown in wastewater tanks. srivastav et al. (1994) report the relative growth values of salvinia spp. at 1 ppm of cr concentration as 1.15 and at 1 ppm ni concentration as 1.17. also he reports the relative growth values of spirodela spp. at 1 ppm of cr concentration and at 1 ppm ni concentration respectively as 1.16 and 1.13. in the present study, s. molesta and l. gibba plants grown in wastewater and control sample of s. molesta recorded greater relative growth values. the most likely reason is the low concentrations of heavy metals in wastewater. only cr was present in a concentration higher than 1 ppm in the wastewater used in the present study. the moisture content of fresh s. molesta may be the reason for the high relative growth value in control sample. 4. discussion according to the obtained results, s. molesta and l. gibba have proven their potential for the removal of nutrients and heavy metals from municipal wastewater. s. molesta has performed well in the removal of total nitrogen, phosphates, bod and cod reporting the removal efficiencies respectively as 73.35%, 72.63%, 71.51% and 61.98%. also, l. gibba demonstrated a significant removal of total nitrogen, phosphates, bod and cod reporting the removal efficiencies respectively as 62.18%, 77.28%, 67.24% and 78.96%. s. molesta was more efficient in the removal of total nitrogen and l. gibba showed a greater removal efficiency for cod. the average cr, cu, fe, ni and pb removal efficiencies of s. molesta were 81.66%, 69.81%, 65.26%, 66.39% and 74.85% respectively. the average cr, cu, fe, ni and pb removal efficiencies shown by l. gibba were 86.99%, 69.77%, 73.10%, 61.87% and 85.74% respectively. l. gibba performed greater removal efficiencies in the removal of cr and pb when compared to s. molesta. but, the bio 76 concentration factors recorded by s. molesta and l. gibba in the uptake of selected heavy metals were always lower than 1000 in the present study. visual toxicity symptoms were not observed in the plant materials grown in the wastewater tanks. however, both s. molesta and l. gibba can be considered as suitable candidates for the removal of nutrients and these heavy metals (cr, cu, fe, ni and pb) from wastewater even at low heavy metal concentrations. 5. conclusion this study was carried out to investigate the nutrient and heavy metal removal potential and the efficiencies of s. molesta and l. gibba for the removal of nutrients and selected heavy metals (cr, cu, fe, ni and pb) from municipal wastewater samples collected from the influent of moratuwa-ratmalana wastewater treatment plant. these aquatic plants have the potential of phytoaccumulation of nutrients and heavy metals from water. this strategy is a low cost and eco-friendly technology for the treatment of wastewater. the invasive nature of s. molesta and the fast growth rate of l. gibba are the practical issues that may arise in the practical use of these plants. references ali, h., khan, e. and sajad, m.a., 2013. phytoremediation of heavy metals-concepts and applications. chemosphere, 91:869-881. al-khafaji, m.s., al-ani, f.h. and ibrahim, a.f., 2017. removal of some heavy metals from industrial wastewater by lemna minor. ksce journal of civil engineering, 1-6. danushika, u.a.a.g., bandara n.j.g.j., and rupasinghe s.k.l.s., "performance assessment of moratuwa-ratmalana biological nutrient removal industrial wastewater treatment plant." proceedings of international forestry and environment symposium, 21. 2017. dhir, b. and srivastava, s., 2011. heavy metal removal from a multi-metal solution and wastewater by salvinia natans. ecological engineering, 37:893-896. kalagbor, i.a. and opusunju, k., 2015. a comparison study of dry and wet ashing methods used for the assessment of concentration of five heavy metals in three vegetables from rivers state, international journal of environmental research and public health, 2:16-22. körner, s. and vermaat, j.e., 1998. the relative importance of lemna gibba l., bacteria and algae for the nitrogen and phosphorus removal in duckweed-covered domestic wastewater. water research, 32:3651-3661. koutika, l.s. and rainey, h.j., 2015. a review of the invasive, biological and beneficial characteristics of aquatic species eichhornia crassipes and salvinia molesta. applied ecology and environmental research, 13:263-275. kumari, m. and tripathi, b.d., 2014. effect of aeration and mixed culture of eichhornia crassipes and salvinia natans on removal of wastewater pollutants. ecological engineering, 62:48-53. lokuge, u.m.l., 2016. a study on the phytoremediation potential of azolla pinnata under laboratory conditions. journal of tropical forestry and environment, 6. mkandawire, m. and dudel, e.g., 2005. accumulation of arsenic in lemna gibba l. (duckweed) in tailing waters of two abandoned uranium mining sites in saxony, germany. science of the total environment, 336:81-89. mohedano, r.a., costa, r.h., tavares, f.a. and belli filho, p., 2012. high nutrient removal rate from swine wastes and protein biomass production by full-scale duckweed ponds. bioresource technology, 112:98-104. ng, y.s. and chan, d.j.c., 2017. wastewater phytoremediation by salvinia molesta. journal of water process engineering, 15:107-115. journal of hazardous materials ranjitha, j., raj, a., kashyap, r., vijayalakshmi, s. and donatus, m., 2016. removal of heavy metals from industrial effluent using salvinia molesta. international journal of chemtech research, 9: 608-613. abhayawardhana et al. /journal of tropical forestry and environment vol. 9, no. 02 (2019) 65-77 77 srivastav, r.k., gupta, s.k., nigam, k.d.p. and vasudevan, p., 1994. treatment of chromium and nickel in wastewater by using aquatic plants. water research, 28:1631-1638. thayaparan, m., iqbal, s.s., chathuranga, p.k.d. and iqbal, m.c.m., 2013. rhizofiltration of pb by azolla pinnata. international journal of environmental sciences, 3:1811. uysal, y., 2013. removal of chromium ions from wastewater by duckweed, lemna minor l. by using a pilot system with continuous flow, 263:486-492. verma, r. and suthar, s., 2015. lead and cadmium removal from water using duckweed-lemna gibba l.: impact of ph and initial metal load. alexandria engineering journal, 54:1297-1304. zaltauskaite, j., sujetoviene, g., cypaite, a. and auzbikaviciute, a., 2014, january. lemna minor as a tool for wastewater toxicity assessment and pollutants removal agent. in environmental engineering. proceedings of the international conference on environmental engineering. icee. 9, p. 1. vilnius gediminas technical university, department of construction economics and property. zayed, a., gowthaman, s. and terry, n., 1998. phytoaccumulation of trace elements by wetland p lants: i. duckweed. journal of environmental quality, 27:715-721. 10 *correspondence: kapila.s.gunarathne@gmail.com © university of sri jayewardenepura smallholder rubber farming based agro-tourism: potential, attitude and challenges in sri lanka-a case study in moneragala district p.k.k.s. gunarathne1*, t.m.s.p.k. tennakoon2, j.c. edirisinghe3, k.k.i.jayasundara1 1rubber research institute of sri lanka, telewala road, ratmalana, sri lanka 2department of geography, university of sri jayewardenepura, gangodawila, nugegoda 3department of agribusiness management, faculty of agriculture and plantation management, wayamba university of sri lanka date received: 10-10-2021 date accepted: 20-12-2021 abstract this study was carried out to assess the possibilities of the rubber farming based agro-tourism (rfat) in the smallholder rubber sector in moneregala. the study covered 222 rubber smallholdings in eight rubber growing ds divisions and was conducted in 2019 through a questionnaire survey and focus group discussions. stratified random sampling technique was applied. rubber agro-tourism potential index (rapi) was developed to measure the resource availability in rubber smallholdings. the 18 potential rubber farming practices which could be offered to a tourist were identified. the younger rubber smallholders (rss) were more aware of the agro-tourism. young, educated and experienced rss had a highly positive attitude for rfat. comparatively, more positive impacts of rfat were highlighted by rss. lack of practical exposure to rfat and low level of different language skills were identified as major constraints by the rss. badalkumbura ds division was the most potential resourceful area for development of rfat in moneragala. hence, there is an utmost need to work for uplifting the rfat industry from governmental, non-governmental, private and community sectors. there is a felt necessity to implement awareness programmes, training and workshops, especially for rss and small-scale tourism business entrepreneurs to uplift the rfat industry through forming the relevant organizations. this information will be provided with an immense value for policy makers, researchers, extension planners to make the rfat industry a profitable, socially acceptable and an environmentally friendly approach for the betterment of the nation. keywords: agro-tourism, smallholder rubber farming 1. introduction tourism is a typical activity where the public participates widely, and the evidence of travel and tourism can be identified even since the pre-historic era in the world. tourism is among the three largest industries in the world and has been the primary source of foreign exchange earnings in 46 developing nations. globally, tourism is rated as the fastest-growing industry and employing 10% of the world labour force (wttc, 2019). the most of the developing countries have exposed their economies to the tourism industry (mubarak, 2019). in sri lankan context, tourism is one of the fastest growing industries and in 2019, the foreign exchange was us$ 3,606.9 million and 4.3% gdp contribution to the country. although in sri lanka tourism is a seasonal industry, it has provided around 400,000 direct and indirect employment opportunities (stda, 2019). according to the diversified natural settings and various patterns of human life, mass tourism has been shaped. mailto:kapila.s.gunarathne@gmail.com gunarathne et al. /journal of tropical forestry and environment vol. 11 no. 02 (2021) 10-23 11 the new phenomena and forms of tourism concepts in the modern world as beach tourism, religious tourism, cultural tourism, nature tourism, adventure tourism, eco-tourism, community-based tourism, indigenous tourism and agro-tourism. among them, agro-tourism is an emerging and very prospective sub-sector of tourism which is one of the most extensive and influential forms of tourism in europe and asia (oppermann, 1995; sharpley and vass, 2006; upadhyaya, 2006; haugen and vik, 2008). agro-tourism is the amalgamation of tourism and agriculture. sonnino (2004) defines as the tourism activities exercised by farmers through the utilization of their own farm in consonance with the rationale of "connection,” “complementarity” and “nonprevalence. agro-tourism is constantly hybridizing and evolving which promotes excitement and discovery (ogidi and odiba, 2014). agro-tourism is defined as any custom developed on a working farm with the objective of attracting tourists (barbieri and mshenga, 2008). due to low revenue from farming activities, it has led farmers to diversify from the agricultural base alternative economic schemes under the sustainable development paradigm (rickard, 1983; fleischer and pizam, 1997; mcgehee and kyungmi, 2004). agro-tourism has four forms of development aspects; can be developed as alternate industry to agriculture which has failed to evolve despite constant focus, can be developed to preserve the viability and durability of rural localities and can be developed as an activity to rejuvenate non-profitable agricultural activity (khanal and shrestha, 2019). it can be used to persuade and inspire farming communities to raise their crops in an eco-friendly behaviour and to conserve the biodiversity of farms (dangol and ranabhat, 2007). it allows tourists to come in close contact with the dwellers of small, rural villages and to be engaged in traditional ways of agriculture still prevailing in this age. tourists can get a chance to know about different indigenous agricultural practices, such as how crops are planted, harvested, production of value added products and marketing (pandey and pandey, 2011). it provides appropriate paths to protect natural habitats and resources and naturally beautiful scenic areas (singh and mishra, 2016). one of the prime rationales of agro-tourism is to create the opportunity to contribute to one’s community, develop the hospitality tradition of the people, build-up morals and cultural discipline and combine agriculture with recreation (putzel, 1984; maude and van rest, 1985; weaver and fennell, 1997; getz and carlsen, 2000). sri lanka is endowed with the agro-biodiversity and embellished with the geographical tranquil sight and landscape. being, sri lanka is the oldest rubber (hevea brasiliensis) producing country in the world with commercial production having commenced more than 125 years ago and there is an unlimited scope of the agro-tourism. rubber is one of the major plantation crops in sri lanka in terms of export earnings and employment generation. rubber sector contributed 0.3% to the gross domestic production in 2020 (cbsl, 2019) yet far behind the expected target, due to various reasons (gunarathne et al., 2020). rubber has been a popular cash crop among smallholders in the island and there are nearly 200,000 smallholders operating in14 rubber growing districts in the country (mpi, 2017) with different rubber landscapes. 12 the rubber cultivation is expanded to the agro-ecological regions of il1c, il2 and im2b among the eight divisional secretariat (ds) divisions of moneragala which aims to transform the existing system of shifting cultivation and cash crop farming to more ecologically stable cultivation systems with proper land management by villagers and individuals. rubber farming (rf) was originally expanded to moneragala with two major objectives in millennium development goals namely, poverty alleviation and livelihood sustainability (wijesuriya et al., 2011). ever since natural rubber cultivation was started by smallholders in late 1990s in moneragala the most of farmers adopted to rf under the subsidy scheme developed by the rubber development department of sri lanka. however, smallholder rubber in moneragala is a more recent phenomenon after 1996. since then, the rubber area in moneragala has increased moderately, but at a more rapid pace since 2005 as many smallholders have been introduced via smallholder rubber development project by the government. although, rubber cultivation has more than 20 years of economic lifespan, profitability of rf is becoming low in last decade due to various reasons. therefore, agro-tourism is an important alternative source of income for rural small-scale rubber farmers and sustainability of the rf in moneragala. but, it is still the infant stage in sri lanka as well as other rf countries in the world. although, the rubber industry proclaims an ancient history around 125 years in sri lanka, still it has not been used to promote tourism in rubber smallholder sector. therefore, the main objective of the study is to figure out the possible avenues of smallholder rf in the agro-tourism sector and identification of the strategies to promote the rubber farming based agro-tourism (rfat) sector with the aiming of rubber land productivity in moneragala. 2. methodology the study was carried out in rubber growing ds divisions in moneragala district in 2019. data collected through a household questionnaire survey, focus group discussions, observations and secondary data. stratified random sampling technique was applied for the rubber smallholder survey. the point scheme was developed (anon, 2002) with the assistance of the experts of the tourism and rubber industries for resource evaluation (table 01) to develop the rubber agro-tourism potential index (rapi). it referred to 17 critical areas of rubber smallholdings which are of much importance in developing the rfat industry. the total points were calculated for each smallholding with the use of which, the rapi for each smallholding was calculated using equation 1. the sum of the rapi of each ds division was calculated and average was measured. accordingly, the each rubber cultivated ds division was ranked using the average value of the rapi. table 01. the point scheme developed for resource evaluation to develop rapi type of resource criteria and points access road grade of the home well maintained tarred road (3), gravel road partly tarred (2), gravel road (1), no road facilities (0) access road grade of the immature rubber cultivation well maintained tarred road (3), gravel road partly tarred (2), gravel road (1), no road facilities (0) access road grade of the mature rubber cultivation well maintained tarred road (3), gravel road partly tarred (2), gravel road (1), no road facilities (0) accommodation facilities of living home very satisfactory (3), moderate satisfactory (2), satisfactory (1), unsatisfactory (0) communication facilities in the rubber land mobile phone coverage and internet (3), mobile phone coverage (2), lack of proper telephone facilities (0) language skills of rubber farmer able to speak and understand english (3), english can be understood (2), english neither be understood nor spoken(0) distance from the home to rubber cultivation both situated in the same vicinity (3), <1 km (2), 1-2 km (1), >2 km (0) gunarathne et al. /journal of tropical forestry and environment vol. 11 no. 02 (2021) 10-23 13 availability of immature extent yes (1), no (0) availability of intercrops in the immature rubber lands yes (1), no (0) availability of multi-crops in the mature rubber lands yes (1), no (0) availability of rolling facilities yes (1), no (0) availability of smokehouse yes (1), no (0) availability of other viewpoints close (<1km) to the rubber plantation yes (1), no (0) availability of natural forests close (<1km) to the rubber plantation yes (1), no (0) availability of waterbodies close (<1km) to the rubber plantation yes (1), no (0) availability of fauna in the rubber plantation ability to observe large mammals and rich in bird life (3), absence of large mammals but rich in birdlife (2), scarcity of wildlife within the rubber plantation (0) availability of other cultivated crops without rubber yes (1), no (0) rapi (eq.1) was developed using the cumulative value of the points of each rubber smallholding. rubber agro-tourism potential index (rapi)= score obtained by the smallholding×100 maximum possible score according to the rapi variation, potential level of smallholdings for rubber based agro-tourism was categorized as very low (<25%), low (26-50%) medium (51-75%) and high (76%). the level of attitude of farmers was measured with five response options (5=extremely good idea, 4=good idea, 3=moderate, 2=poor idea, and 1=very poor idea). the possible impacts and constraints of rf were listed out by discussing with the smallholders prior to the questionnaire survey and the list was then administrated to rubber smallholders (rss) for response. possible impacts and constraints of rfat were also measured and constraints were ranked. 3. results and discussion 3.1. key socio-economic profile of the rubber smallholders socio-economic status is the position that individual farmer occupies regarding the prevailing average standards, material possession, social participation and other factors (kromkratoke and suwanmaneepon, 2017). shankaraiah and swamy (2012) reported that attitude is related to the socio economic status of the farmers. therefore, key socio-economic characteristics of rss were used to identify the relationships (table 02). the age of the rss varied from 21-78 years, and the majority was young and were 40 years or below. the half of sample of the rss had studied up to o/l while about 9% of rss had studied up to grade 5 and 21%, up to advanced level. around 30% of rss had less than 15 years of experience in farming, while 36% reported to have more than 36 years of experience. the mean land size was 1.5 ac. the largest smallholdings were about 1-1.9 ac. about 50% of the lands were less than 3 ac. in size. most of rss (82%) had 4-6 memberships in village-level societies. (1) 14 table 02. distribution of key socio-economic characteristics of rubber smallholders key socio-economic characteristics and their categories % age (years) <40 42 41-60 38 >61 20 range 21-78 education level up to grade 5 9 up to grade 8 19 up to ordinary level 51 up to advanced level 21 experience in farming (years) <15 31 16–25 15 26-35 18 >36 36 range 5-55 land size (ac.) < 1 7.5 1-1.9 38 22.9 7 3-3.9 22.5 4-4.9 21 >=5 4 mean 1.5 range 0.75-10.5 number of memberships in non-rubber societies <3 16 4-6 82 >6 2 gunarathne et al. /journal of tropical forestry and environment vol. 11 no. 02 (2021) 10-23 15 3.2 the potential of agro-based tourism in moneragala moneragala (6.7563° n and 81.2519° e) was a district in uva province in sri lanka where people of multiple cultural and ethnic groups can be found. it was located in the southeastern quadrant of sri lanka, bordering the districts, namely, ampara from the north and east, badulla from the west and north, hambantota from the south, and ratnapura from the south west. the total land area was 565,930 ha, representing approximately 13% of the country's total land area. the population of the district was predominantly distributed in rural areas, approximately 83%. moneragala was the district of which the highest percentage (52.3%) of the population was employed in agriculture in sri lanka. the majority was adopted subsistence agriculture (65%) as the mainstay of their livelihood. there were 95,718 farmers within 21,817 households where the agricultural household population was 343,037. the rural agriculture entered on artificial irrigation tanks and complex irrigation canal systems with smiling tracks of paddy fields, especially during the great season that coincides with the tourist season of the country. it also consisted of fruit and vegetable gardens, mixed home gardens, shifting cultivations, and many other closely and distantly related activities. the harvesting period of most of these crops, vegetables, and fruits also falls during the tourist season, making the sector more attractive to tourists (silva and wimalaratana, 2012). moneragala was mainly located in the dry zone but it had both intermediate and dry climatic conditions. combination of three agro-ecological regions, has made the region rich in bio diversity, gorgeous natural forests, greenish paddy fields, beautiful mountain ranges and conspicuous sanctuaries, sacred places of deities, heterogeneous climate and landscapes, talented and skilful village communities with courteous disposition. silva and wimalaratana (2012) highlighted that there were potentials for tourism with the nature-based, cultural, heritage, and spiritual, health, sports, agro and adventure tourism in moneragala. moneragala was also loaded with ancient structures with a great appeal for local and international tourists. such historical sites as old monasteries, fortresses, pagodas, and statues were some of the sites with sentimental attraction for the local tourists. also, this was a place surrounded by scattered ruins, artificial irrigation tanks and canal systems, rich fauna and flora, and village communities with numerous talents and skills. they were the people with traditional knowledge and practices of traditional healing methods, folk music, and dances handed down from generation to generation. kataragama and yala are extremely popular tourist destinations among local and foreign travelers. there are other places in the district with great local tourist attractions, such as yudaganawa, maligawila, buduruwagala, and dembatamala viharaya. it was an obvious fact that moneragala was one of the resourceful districts in sri lanka with huge potentials for the promotion of tourism in local as well as international contexts. 3.3. the potential of rubber-based agro-tourism in moneragala at present, rf is prominent in moneragala, which comprises the agro-ecological zones, namely, dl1b, il1c, and im2b, among the perennials. there are about 5,087 hectares of rubber lands and 9,514 rss (mpi, 2019) in moneragala. the distribution of the rubber lands and rss in the ds divisions and agro ecological regions in moneragala is listed in table 03. 16 table 03. distribution of rubber lands in ds divisions of moneragala district ds division agro-ecological region number of smallholders rubber extent (ha) badalkumbura im2b, il1c 3607 1877 moneragala im2b, il1c 1421 869 medagama im2b, il1c 1517 695 bibila il2, il1c 919 469 madulla il2 831 427 buttala il1c 658 421 wellawaya im2b, il1c 405 221 siyambalanduwa il2 156 109 total 9,514 5,087 source: mpi, 2019 rubber was a plantation crop, of which its mature period was suitable for harvesting after reaching the harvestable girth and was preceded by an immature period (rrisl, 2001). according to the rf system, two basic potential rfat phases could be identified, which had the qualities and abilities that may develop and lead to success in the trade namely; 1. immature stage rf with intercropping and 2. mature stage rf with rubber processing/sheet making. the potential activities of rf can be utilized for rfat, and the seasonal calendar of the rf is shown in table 04. table 04. the potential elements which can be offered to a tourist in agro-based smallholder rubber farming in moneragala activity time period (month of the year) j f m a m j j a s o n d immature stage of rubber farming rubber planting watering weeding manuaring branching induction soil conservation intercropping of rubber farming planting weeding manuaring harvesting processing bee-keeping mature stage of rubber farming tapping weeding manuring sheet making sheet smoking bee-keeping gunarathne et al. /journal of tropical forestry and environment vol. 11 no. 02 (2021) 10-23 17 in the immature stage of rf, agronomic practices of watering, weeding, branching, and soil conservation could be practiced throughout the year, while planting and manuring were seasonal practices. most of rss (97%) practiced intercropping during the immature stage, and prominently cultivated crops are banana (musa acuminate) (51 %), maize (zea mays) (19 %), cowpea (vigna unguiculata) (8%), passionfruit (passiflora edulis) (1%), groundnut (arachis hypogaea) (12%) and vegetables (9%). thus, two percent of rss adopted cocoa (theobroma cacao) as mix cropping with mature rubber plantations. therefore, basic agronomic practices of intercropping such as planting, watering, weeding, manuring, harvesting and processing were identified as potential agro-tourism activities during the whole year (table 03). bee-keeping was practiced by 2% of rss both in immature and mature rubber plantations, and it was a huge potential activity provider in agro-tourism. basic agronomic practices of mature rubber smallholdings such as weeding and manuring, were identified as potential rfat activities which could be practiced throughout the whole year from april to july. activities such as tapping, sheet rubber making and smoking were identified as potential activities of the mature stage rf which could be practiced throughout the year. in general, tapping was started early in the morning around 5.30 a.m. which aroused the necessity of provision of accommodation facilities for tourists. only 45% of rubber smallholders had processing and smoking facilities for making sheet rubber. both diamond and smooth rollers and smokehouse were required to produce sheet rubber. but, nearly 40% of the sample had rolling facilities to make rss and 65% of the sample used their own smokehouses for drying of sheets. 3.3 awareness level of the rubber smallholders on rubber farming based agro-tourism most of the rubber smallholders (68%) were aware of rfat. figure 01 shows the age structure of the rss and the awareness level of rfat. the group of rss who were between 21 to 40 years of age was more aware of the rfat than the other rss where, the awareness level of age group of 71-80 years was zero. rss who have less than 1 acre showed zero awareness level while, rss who have more than 3 acres showed a high level of awareness (figure 02). it is concluded that rss owned more rubber land extent were more aware of agro-tourism. figure 01. age structure of the rubber smallholders and awareness level of rubber farming based agro-tourism 18 figure 02. land extent of the rubber smallholders and awareness level of rubber farming based agro tourism 3.4 attitude level of the rubber smallholders on rubber farming based agro-tourism the level of attitude of rss on rfat is shown in figure 03. the majority of the rss answered it as an extremely good idea (62.5%), whereas an extremely poor idea was highlighted by the least number of rss (4%). the following responses, namely, good idea, moderate and poor idea, were indicated by 18%, 10.5%, and 5% of rss, respectively. figure 03. farmer’s level of attitude on rubber farming based agro-tourism 3.5 relationship between personal characteristics of the rubber smallholders and their attitude towards rubber farming based agro-tourism the findings of table 05 revealed that variables such as rss’ education level and farming experience had a positive and significant relationship with the attitude of rss at a five per cent level of significance. as far as age was concerned, it showed a negative and significant relationship with the attitude of rss at a five percent level of significance. however, other variables, namely rubber extent and memberships of societies, were found to have a non-significant relationship with the attitude of rss towards rfat. it is concluded that younger rss, with more farming experience and rss with more education level were interested in rfat in moneragala. gunarathne et al. /journal of tropical forestry and environment vol. 11 no. 02 (2021) 10-23 19 table 05. relationship between personal characteristics of the rubber smallholders and their attitude towards rubber farming-based agro-tourism variable correlation coefficient (r) education level 0.6011 * age -0.7578* farming experience 0.7370* rubber extent -0.0631ns memberships of the societies 0.0359 ns * significant at the 0.05 level ns=not-significant 3.6 possible impacts of rubber based agro-tourism when the willingness of the rss in taking part in the advancement of the rfat in moneragala was considered, 52% of the rss showed interest in joining agro-tourism full-time, 31% showed readiness in part-time participation where only 11% were not interested, and 5% of the rss were found yet to be decided. rfat could give rise to numerous repercussions in various aspects of society and the rss themselves. therefore, the awareness of the community on some identified impacts of the rfat was discussed with them, and those impacts are shown in figure 04. all of the rss agreed upon the fact that by the implementation of an agro-tourism project, there was a great possibility of earning an extra income and a high number of extra job opportunities (95%) for the community. around 65% of rss agreed upon the fact that there was a higher possibility to sell village products and improve the infrastructure facilities of the village, while 75% of rss agreed to have an increased chance of improving their linguistic skills. apart from this, some community members had skills in sewing and making handicrafts using various materials which were abundant in the neighborhood. these smallscale industries could be integrated with rfat to enhance their trades with the help of tourists. therefore, the members of the surrounding rubber community could be selected and trained in different skills related to agro-tourism for the betterment of household income. most of rss contemplate that the culture of the community might be changed due to the effects of rfat (55%) and the younger generation may absorb and imitate the visitors’ behavior, clothing, and other cultural attributes as well. they also envisage that the environment may also be affected by tourism (5%) due to the accumulation of litter on the land and in the waters resulting in environmental and water pollution. in a comparison of the responses given to both negative and positive impacts, the negative responses seem to have the least importance. on the contrary, effects of social diseases, increase in alcoholism and change in religion were highlighted by a significantly high number of farmers as 5%, 35% and 20%, respectively. 20 figure 04. effects on the rubber smallholders and community due to rubber farming based agrotourism 3.7 resource availability in the rubber growing ds divisions resources in each smallholding for the potential development of rfat were assessed using the rapi in each ds division. the percentage of rss of each category in each ds division is illustrated in figure 5. with the consideration of overall capacity with regard to the available resources to develop moneragala rfat, it was clear that 27% of rubber cultivations were in a high potential category of the rapi. however, each ds division showed a different level of capacity to develop rfat. the highest percentage of rss in the high level category of rapi was received by badalkumbura ds division, followed by other ds divisions, while the lowest was siyambalanduwa. the reason for the above result may be due to badalkumbura and siyambalanduwa being the highest and lowest rubber density areas in moneragala, respectively. e ff e c ts o f th e a g ro -t o u ri sm environmental degredation 5 social diseases 5 cultural changes 55 change in religion 20 increase in alcoholism 35 improve the infrastructure facilities in the village have a chance to sell village products 65 67 improve languege skills of farmers 75 extra job opportunities for commounity 95 extra income for the farmers 100 0 20 40 60 80 100 120 gunarathne et al. /journal of tropical forestry and environment vol. 11 no. 02 (2021) 10-23 21 figure 05. resource availability in the rubber growing ds divisions for rubber farming based agrotourism 3.8. constraints noticed by rubber smallholders while implementing rubber farming based agro tourism the findings in table 06 shows that, among all the constraints noticed by rss when implementing rfat, lack of practical exposure (rank i) and low level of different language skills (rank ii) were the major constraints. because this was the first experience of the rubber farmers in this trade, lack of accommodation facilities and cost involvement for construction of smokehouses and processing centers of rubber were also important issues. therefore, policymakers should pay timely attention to establishing the proper material distribution (rollers and smokehouses) should be organized in a more efficient way. table 06: constraints noticed by farmers while implementing rubber farming based agro-tourism constraints % of farmers rank lack of practical exposure 99 i low level of different language skills 97 ii lack of accommodation facilities 87 iii cost involvement for construction smoke houses and processing centres of rubber 85 iv 4. conclusion this study had made an attempt to identify the potentials, possible impacts and issues of the rfat in moneragala. moneragala district had an enormous potential for developing mass tourism as well as agrotourism. based on this study, following notions could be established. sri lanka, being an agricultural country and tourism being one of the major economic divisions, rfat can be developed as one of the emerging mode of trades in smallholder rubber sector. the 18 potential elements in rf which could be offered to a tourist for a successful future of the rfat were identified. comparatively, positive impacts of rfat were highlighted by all the rss. it would provide farmers considerable revenue, offering an opportunity for an alternative approach to retail rss’ products and services. the rati used in this study could be developed and applied further to identify and compare the potential sites, in order to identify the resource availability through which rfat could be developed in the rubber plantation sector also. 22 the younger the rss the more the awareness about the agro-tourism. young, educated and experienced rss had highly positive attitude for the rfat. therefore, it was a worthy indicator to implement a pilot project with them. the most of facts namely, lack of practical exposure to rfat and low level of different language skills being identified as major constrains by the rss and badalkumura ds division was the most potential resourceful area for development of rfat would have immense value for policy makers, researchers, extension planners to make the rubber industry a profitable, socially acceptable and an environmentally friendly approach for the betterment of the nation. 5. recommendations to form a coordinating frame with the public, private and community participation to promote the rfat was paramount. suggestions for enabling of these organizations to implement required practices for achieving objectives were; 1. knowledge on agro-tourism (management, operation and maintenance), 2. identification of other ecotourism sites in the area, 3. provide financial assistance to local agencies for infrastructure development, 4. giving publicity to promote selected sites and 5. arrange new visitor packages for rfat sites. furthermore, badalkumura ds division could be developed as rfat site through a pilot project in collaboration with relevant authorities in public and private sector. this model could be utilized as a demonstration to promote rfat in other potential ds divisions in moneragala. it will be better income diversification option in the rubber smallholding sector in sri lanka. references anon. 2002. ecotourism development strategy in sri lanka and southern region. sri lanka tourist board, colombo. barbieri, c. and mshenga, p. m. 2008. the role of the firm and owner characteristics on the performance of agritourism farms. sociologia ruralis 48:166-183. central bank of sri lanka, 2019. central bank annual report, central bank of sri lanka, colombo, sri lanka. dangol, r, d. and ranabhat, b. 2007. developing agro-ecotourism in nepal. nttr, 12-25. fleischer, a. and pizam, a. 1997. rural tourism in israel. tourism, 18(6):367-37. getz, d. and carlsen, j. 2000. characteristics and goals of family and owner-operated business in the rural tourism industry and hospitality sectors. tourism management, 21(6):547–560. gunarathne p.k.k.s., tennakoon t.m.s.p.k. and edirisinghe j.c 2020. strategies for improving rubber productivity in smallholder rubber farming: a case study in moneragala district of sri lanka. in proceedings of the seventh international conference on multidisciplinary approaches, university of sri jayawardenapura, gangodawila, sri lanka: 68. haugen, m.s. and vik, j. 2008. farmers as entrepreneurs: the case of farm-based tourism. international journal of entrepreneurship and small business, 6(3):321-337. khanal, saugat & shrestha, m. 2019. agro-tourism: prospects, importance, destinations and challenges in nepal. archives of agriculture and environmental science. 4:464-471. kromkratoke, k., & suwanmaneepong, s. 2017. socio-economic characteristics of rubber farmer in the drought area in sakaeo province, thailand. international journal of agricultural technology, 13(7.2):1947-1957. maude, a. j. and van rest, d. j. 1985. the social and economic effects of farm tourism in the united kingdom. agricultural administration, 20: 85-98. mcgehee, n.g. and kyungmi, k. 2004. motivation for agri-tourism entrepreneurship. journal of travel research: 161-170. ministry of plantation industries of sri lanka, 2017. plantation sector statistical pocket book, sri lanka. ministry of plantation industries of sri lanka, colombo 2, sri lanka. kaldeen, m. 2019. managing knowledge management: identifying and evaluating enablers and gunarathne et al. /journal of tropical forestry and environment vol. 11 no. 02 (2021) 10-23 23 hinders from the perspective of practicing managers from tourism sector in sri lanka, international journal of recent technology and engineering. 8:4167-4171. ogidi and odiba 2014. benchmarking as a tool of tqm in the delivery of quality services/products. oscsr journal of business and entrepreneurship, 1(3):52-63. oppermann, m. 1995. holidays on the farm: a case study of german hosts and guests. journal of travel research: 63-67. pandey, h. and pandey, p.r. 2011. socio-economic development through agrotourism: a case study of bhaktapur, nepal. the journal of agriculture and environment, 12:59-66. putzel, s. 1984. farm holidays: combining agriculture and recreation. agrologist (fall): 20-21 rubber research institute of sri lanka (2001). hand book of rubber, rubber research institute of sri lanka. 15-32. rickard, r. c. 1983. the role of farm tourism in the less favoured areas of england and wales. new york: exeter: university of exeter agricultural economics unit. shankaraiah, n & swamy, b. 2012. attitude of farmers and scientists towards dissemination of technologies through mobile message service (mms). tropical agricultural research. 24(1):31-41. sharpley, r. and vass, a. 2006. tourism, farming and diversification: an attitudinal study. tourism management. 1040-1052. silva, d.d.,wimalaratana,w. 2012. community based sustainable tourism development in sri lanka: special reference to moneragala district. singh, p. and mishra, m.k. (2016). identifying the potential of agri-tourism in india: overriding challenges and recommend strategies. international journal of core engineering & management (ijcem), 3(3):7-14. sonnino, r. 2004. “for a ‘piece of bread’ interpreting sustainable development through agritourism in southern tuscany. sociologia ruralis, 44(3):285-300. sri lanka tourism development authority. (nd.). retrieved from http://www.sltda. lk upadhyaya, r. 2006. agro-tourism outlook. nepal travel trade reporter, 20(26):209. weaver, d. b. and fennell, d. a. (1997). the vacation farm sector in saskatchewan: a profile of operations. tourism management, 18(6):357–365. wijesuriya, wasana, dissanayake, d.m.a.p., herath, keminda., and gunaratne, p.k.k.s., (2011) constraints in sustainable smallholder rubber farming in moneragala district. journal of rubber research institute of sri lanka. (91):61-73. wttc (world travel and tourism council). 2019. travel and tourism economic impact, 2019 london: wttc. 28 modeling height-diameter relationship and volume of teak (tectona grandis l. f.) in central lowlands of nepal a. koirala *1, a. r. kizha 1 and s. baral 2 1school of forest resources, university of maine, orono, usa 2institute of forestry, tribhuvan university, nepal date received: 18-12-2016 date accepted: 06-04-2017 abstract forests have played a vital role in the socio-economic development of nepal with their productive, protective, and bio-esthetic functions. stand height-diameter as well as volume estimation is very critical in forest management. this research modelled height-diameter relationship as well as tree volume for teak (tectona grandis), a well-known tropical hardwood species, in central lowland nepal. data was collected from a teak plantation site in sagarnath forest development project (sfdp), nepal. forty-four trees representing different diameter classes were felled. the diameter at breast height (dbh) and height (h) of the trees ranged from 6.1 to 58.9 cm and 6.1 to 26.1 m, respectively. several height-diameter models were fitted and evaluated for certain training and validating criteria. the height-diameter equation of , performed well and was selected to be the best model for h prediction from dbh. also, the volume equation of was selected as best fitted equation, using dbh and height as independent variables. the height in this volume equation was to be calculated from selected height-diameter equation to predict height. the equations developed are the first of their kinds officially documented for teak species in central lowlands of nepal. keywords: allometric equation, diameter class, hardwood species, plantation, tropical forest. 1. introduction teak (tectona grandis l.f.) is a very important and valuable multipurpose tropical hardwood tree species of south and south-east asia. the natural distribution of the species ranges from india to burma, laos and thailand (hansen et al., 2015). teak plantations have been set up in large scale throughout the world both within and out of its natural distribution. at present, teak is one of the major planted tree species in indonesia, tropical african countries like nigeria, ghana and ivory coast, south and central american countries like panama, costa rica, brazil and others (tewari and mariswamy, 2013). it has been widely used for furniture, ship building, carved-wood products and residential constructions. the strength, durability, and ease of working without cracks are some properties that make teak so popular among the regions for forestry plantations. in nepal, the government initiated teak plantations in chiliya of rupandehi district in 1960 followed by a large-scale plantation in sagarnath forestry development project (sfdp), sarlahi district and ratuwamai project, jhapa district (thapa and gautam, 2005). in sfdp, teak forms a major component of the plantations, (eucalyptus comaldulens is being the next); and has been able to meet almost half of the demand for teak within the nation. 1.1 description of teak trees 1.2 *correspondence: anil.koirala@maine.edu tel: +12078897154 issn 2235-9370 print / issn 2235-9362 online ©2017 university of sri jayewardenepura koirala et al. /journal of tropical forestry and environment vol. 07, no. 01 (2017) 28-42 29 teak is a tropical deciduous tree species, belonging to the family-verbenaceae and order-laminales. teak is naturally found in a wide range of climatic conditions and its natural habitat spans approximately 27.9 million ha. the species grows well in the regions having rainfall and temperature ranging from 900–2,500 mm and 17°–43°c, respectively (die et al., 2012). soils also vary from acidic to fertile alluvial. such huge variation in growing conditions can result in diversity within the growth features and other tree characters such as form, mode of branching, flowering pattern and wood quality. for example, the mean annual volume increment (mai) of teak plantations can range from 2 to > 15 m3·ha-1. the mai of natural stands ranges from 2–8 m3·ha-1 and for plantation this rate could potentially be doubled due to artificial fertilization and irrigation (zahabu et al., 2015). furthermore, the rotation age can vary from 20 years in fertile plantations up to 40-80 years in state held plantation. stump planting is the most common form of tree propagation. however, dibbling of seeds and tissue-cultured plants have also been practiced in the past (kaosa-ard, 1998). 1.2 height-diameter and volume models height (h) and diameter at breast height (dbh) are the most important measures of tree growth and their relationship is useful in determining site-index, calculating tree volume, evaluating site-quality and predicting future growth of the stand (jayaraman and zakrzewski, 2001; wagle and sharma, 2012). these equations can also help in predicting h from dbh, as hs are often sub-sampled due to the difficulty in measurement (coble and lee, 2011). various models describing the height-diameter relationship of different tree species have been modelled in the past (lappi, 1997; trincado and burkhart, 2006; sharma and parton, 2007; budhathoki et al., 2008; coble and lee, 2011). despite the increasing use of biomass and density, volume is the most widely used traditional measure for tree quantity. in forest management, tree heights and dbh have been used to estimate the total and merchantable tree volume. these parameters are preferred due to the ease of acquiring data and the relative accuracy provided by methods employing them. volume models that are able to quantify tree volume are necessary if trees are subjected to fell for commercial uses (mugasha et al., 2016). they are also employed to forecast volumes of other stands having similar conditions. there have been many developments of volume equations since the chronological development of forest measurements and this trend has highly increased after development of computers and sophisticated data analysis mechanisms (weiskittel et al., 2011). although, more than 300 volume and height-diameter equations have been developed in south asia till 2014 (sandeep et al., 2014), no such volume equations for teak in nepal have been documented (thapa and gautam, 2007). in sfdp, volume equations for eucalyptus species were prepared about a decade ago. hence, this study has made an attempt to create a suitable height-diameter equation as well as localized and generic volume equations for teak in the central lowland, nepal. the results can be used by district foresters as well as private land owners to make sound decision for better management of teak plantation. 2. materials and methods 2.1 study area due to legal restrictions to cut large number of teak trees in nepal, sagarnath was the only site within central lowland of the nation which could support research activities of this scale. the field study was carried out at a teak plantation site of sfdp in sarlahi district, nepal during the summer of 2014 (figure 1). the total area of the project is 13,512 ha, of which plantations comprised of 11,796 ha; natural forest–395 ha; protected forest–706 ha; and water bodies–615 ha. the project has engineered massive plantation of teak and eucalyptus since its establishment in 1980s (mandal et al., 2013). 30 the lowland forest of nepal, characterized as “terai-duar savannas and grasslands” eco-region, has an estimated volume of 68.91 million m³, with around 240 million trees (≥5 cm, dbh) and stand density of 583.40 trees·ha-1(fra/dfrs, 2014). the major forest type in the region comprised of mixed hardwood tropical forest with the dominant species being shorea robusta g. f. (91.72 m³·ha-1). the lowland region of nepal extends from 80°4’30” to 88°10’19” east longitudes; and from 26°21’53” to 29°7’43” north latitude. the elevation ranges from 60 to 330 m above mean sea level and the region has a gentle slope. this region of nepal is characterized by hot summers (35° to 45 °c in april/may) with excess down pouring and dry winters (10° to 15 °c in january). the average annual rainfall is from 1,130 to 2,680 mm (fra/dfrs, 2014). figure 1: the location of the study site in sagarnath forestry development project, nepal. 2.2 data twelve sub-compartments (stands) from the study sites spanning over a total of 100 ha were selected for conducting this research. a preliminary inventory analysis was carried out to examine the variation in h, dbh, and volume of trees for the study sites. the average tree density and dbh for the sub-compartments were 344 trees·ha-1 and 35 cm, respectively. the number of samples was then determined ensuring that it represented the whole forest, and all size variation within each sub-compartment. forty-four trees without observable defects and abnormalities were randomly koirala et al. /journal of tropical forestry and environment vol. 07, no. 01 (2017) 28-42 31 selected for destructive sampling. candidate trees excluded those that were open grown, edge of the sub-compartment, and diseased. the dbh of trees were measured at the height of 1.3 m, before felling. all branches were removed from the main stem (bole) and the total length of the main stem was measured. the height of the stump was set at 0.10 m from ground level for all trees felled. total length of the felled tree added with tree top height gave total tree height. stump height was not added for volume estimation. number of trees sampled in different dbh and height classes is presented in table 1. table 1: distribution of felled trees according to the diameter at breast height and height class height (m) 5-10 10-15 15-20 20-25 25-30 total diameter at breast height (cm) 0-10 6 2 8 10-20 1 7 1 9 20-30 3 5 8 30-40 1 2 3 1 7 40-50 3 3 6 50-60 6 6 total 7 13 11 12 1 44 felled trees were then cut to 3 m logs lengths, depending upon the height of the individual tree. diameters (at top, middle and bottom) and length of each section were measured. volume of each log section was calculated using newton’s equation (equation 1), as it was regarded more representative compared to huber’s and smalian’s equations (husch et al., 2002). tree tops were considered as cones and the volume was calculated using respective equation (equation 2): where, vlog and vtree top–volume of log section and tree top, respectively; ab basal area at the bottom of the log section; am– basal area at the middle; at– basal area at the top; r–bottom radius of tree top; and l–length of the log section/ tree top. total stem volume of a single tree was the sum of volume for all sections and tree top, excluding stump. out of 44 trees, 31 (70 % of the data) were randomly selected to build the model, while 13 trees (remaining 30 %) were set aside for analyzing the performance of the model. 2.3 statistical analysis before developing the volumetric model and establishing height-diameter relations, scatter plots were used to check whether the relationships between transformed independent and dependent variables 32 were linear. for the training data set, the goodness of fit statistics for models such as significance of parameter estimates, coefficient of determination r², and standard error were assessed. different transformation models were developed and compared; however, natural logarithmic transformed models were selected (parresol, 1999). the logarithmic transformation equalized the variance over the entire range of volume component and satisfied the assumptions of linear regression (spruge, 1983; basuki et al., 2009; kizha and han, 2016). multi-collinearity was tested using a tolerance value greater than 0.1 and variance inflation factor less than 10. models were also subject to validation after training. there are different approaches for model’s validation. the first one is the re-sampling technique in which the model developed is fitted on to a new set of independent data (bi and hamilton, 1998). another approach would be the use of two independent data sets representing the same area, one set can be used for training and the other for validation. a similar technique was employed in this study by dividing the data collected into two random groups of certain percentages, which was adopted for this study. validation was mainly carried out to test the predictive capacity of the models. for this, the difference between observed and predicted values was also considered. the best-fitted models on both stages i.e. training and validation were selected for predicting h from dbh, and volume from dbh or dbh and h. the models were tested using ordinary least square and non-linear least procedure from nlstools package in r (baty and delignette-muller, 2015; r core team, 2016). four criteria were evaluated during model validation procedure (table 2). table 2: criteria used for validating candidate models criterion equation ideal result aic smaller aic value adjusted r² higher adj. r², ideal value is 1 rmse smaller rmse value; ideal value is 0 bias lower bias –negative of the marginal log-likelihood function; –vector of parameter estimate; p–number of parameters used in the model; n–total non-missing observations; –observed height or volume; –predicted height or volume from model; and –average height or volume of the observed data. 3. results and discussion 3.1 summary of tree data the summary statistics of tree data (table 3) showed that mean dbh for training data set was 27.91 cm, while it was 27.85 cm for validation data. the maximum height of the teak tree in whole data was 26.10 m. although the data was grouped into two sets the average statistics of both sets had no significant difference for all three variables (p<0.05). koirala et al. /journal of tropical forestry and environment vol. 07, no. 01 (2017) 28-42 33 table 3: summary statistics of the data divided into two different sets variable mean standard deviation minimum maximum training data set dbh (cm) 27.91 16.03 6.37 58.92 h (m) 16.13 5.21 5.70 26.10 tree volume (m³) 0.65 0.64 0.01 2.13 validation data set dbh (cm) 27.85 18.70 6.05 57.32 h (m) 16.08 5.66 6.10 23.30 tree volume (m³) 0.76 0.92 0.01 2.44 dbh – diameter at breast height; and h – height of the tree excluding stump height 3.2 height-diameter relationships the initial observation of the scatter plot diagram of h against dbh for all 44 trees showed a non-linear relationship existing between them (figure 2). previous models developed for tree species in different parts of the world also showed similar trends (calama and montero, 2004; sharma and yin zhang, 2004; sharma and parton, 2007; sharma, 2009). figure 2: scatter plot showing height (m), of the trees against diameter at breast height, dbh (cm). 34 the nonlinear models were developed having dbh as the independent variable and h as dependent variable. model h1 incorporated dbh and squared value of dbh as independent variables; whereas h2 included a single independent variable of natural logarithm of dbh. model h3 used dbh and natural logarithm of squared value of dbh as independent variables; while two independent variables – natural logarithm of dbh and squared value of dbh were used in model h4 (table 4). table 4: candidate height-diameter models used in the study height-diameter models model designation h = a + b× dbh + c (dbh)² h1 h = a + b× ln (dbh) h2 h = a + b× dbh + c × ln (dbh)² h3 h = a + b × ln (dbh) + c (dbh)² h4 in the height-diameter models, h is total height of tree excluding stump height; dbh is diameter at breast height at 1.3 m. height above ground; a, b and c are parameters to be estimated; ln(dbh) and ln(dbh)² are natural logarithm of diameter at breast height and its squared value respectively; and h1, h2, h3 and h4 are the candidate height-diameter models. table 5: final statistics of data set for height-diameter models models parameter parameter estimate standard error r² adj. r² rmse bias aic h1 a¹ 4.1607 1.182 0.907 0.888 1.66 <0.0001 58.06 b¹ 0.6704 0.093 c¹ 0.0064 0.002 h2 a¹ 5.2544 1.488 0.928 0.921 1.46 <0.0001 52.72* b¹ 6.8603 0.466 h3 a¹ 7.1423 3.417 0.928 0.914 1.46 <0.0001 54.72 b 0.0441 0.072 c¹ 3.9305 0.847 h4 a¹ 6.5730 2.518 0.928 0.914 1.45 <0.0001 54.71 b¹ 7.4303 0.993 c 0.0004 0.001 1 significant parameters at p = 0.05; and * lowest aic value the goodness of fit statistics was obtained for the four height-diameter models. all parameter estimates of models h1 and h2 were significant at 95% confidence level (table 4). the r² values of all four models were comparatively higher (from 0.907 to 0.928). except h1, more than 91% of height variability were described by all three models (adjusted r² > 0.91). validation of the models for height was carried out using 30% validation data set. comparing the root mean square error rmse, model h4 gave the lowest value of 1.45 followed by models h3, h2 and h1 (table 5). as the bias percent for the validating data set were very low, it was not regarded for factoring the best model. comparing the aic koirala et al. /journal of tropical forestry and environment vol. 07, no. 01 (2017) 28-42 35 values, model h2 showed least value of 52.72. based on the given four criteria and significance of parameter estimates, model h2 was regarded as best model for height estimation from dbh. to find out best model, all models were again analyzed from graphical examination of residual plots (figure 3) and predicted heights laid over observed heights (figure 4). the results from residual plot analysis showed model h2 performed well compared to other models (figure 3b). the analysis of observed and predicted heights showed that in model h1 heights started decreasing when dbhs were higher than 55 cm (figure 4a). except than model h1, all remaining three models showed similar trends of height increment. however, model h2 was considered best fitted in graphical analysis. hence, with lowest aic value and all significant values of parameter estimates, model h2, that has natural logarithm of dbh as independent variable, was considered best height-diameter equation for height estimation from given dbh of teak trees in central lowland, nepal. figure 3: (a), (b), (c) and (d). residual plots of models h1, h2, h3 and h4 respectively, showing residuals at y-axis and fitted values at x-axis. 36 figure 4: (a), (b), (c) and (d). scatter plots of height and dbh (diameter at breast height) showing observed heights and predicted heights from candidate models h1, h2, h3 and h4 respectively. diameter at breast height (dbh) is represented by x, at x-axis and the values at y-axis indicate observed or predicted heights. the selected height-diameter equation i.e. model h2 was compared with two famous height-diameter equations: (a) weibull equation (cited in (zeide, 1993)); and (b) chapman (1961) (chapman, 1961); and richards (1959) (richards, 1959) (cited in (peng et al., 2001)). the observed versus predicted plot was prepared from the height-diameter equations (figure 5). the graphical analysis showed that the prediction of height from model h2 was similar to that of chapman and weibull models for dbh up to 60 cm. however, it overestimated the height of tree above 60 cm dbh range (figure 5). although, there were no trees above 60 cm dbh in sample data, some trees above that range were observed in the study area. koirala et al. /journal of tropical forestry and environment vol. 07, no. 01 (2017) 28-42 37 figure 5: graph of teak model (denoted by blue line) compared with chapman (chapman, 1961) and richards (richards, 1959) (denoted by red line), and weibull (cited in (peng et al., 2001)) (denoted by black line) models for predicting total height of the teak trees in meter ( yaxis) against dbh (diameter at breast height) in cm (x-axis). 3.3 volume equation in volume models, total volume of the bole (stem) can be predicted using dbh only or using both dbh and h. tree form is also often used for volume prediction along with former two variables. however, tree forms were not accounted for this study. based on the observation from scatter plot diagrams between volume and dbh, as well as volume and h (figure 6), several volume models were created. for the selection, the models that were previously developed for different species including teak in different regions were reviewed (cordero and kanninen, 2003; gautam and thapa, 2007; perez, 2008; tewari et al., 2013; chaturvedi and raghubanshi, 2015). figure 6: scatter plot diagrams showing volume of tree in m3 against (a) diameter at breast height, dbh in cm; and (b) height in m. 38 several linear and non-linear volume models were reviewed for the study. the most common six volume equations were selected (table 6). among selected models, v1 was in the equation form having dbh as a single independent variable. the model v2 included dbh and squared value of dbh, while model v3 had dbh and product of dbh and h (observed height in this case), as two independent variables. the last two models were slightly different as both of them had modelled height (h*) from model h2, instead of observed height. table 6: candidate volume models used for the study volume models model designation v = a + b × (dbh) v1 v = a + b × (dbh) + c × (dbh)² v2 v = a + b × (dbh) + c × h v3 v = a + b × (dbh) + c × (dbh)² × h v4 v = a + b × (dbh) + c × h* v5 v = a + b × (dbh) + c × (dbh)² × h* v6 in six candidate volume models, v is the total volume of the tree above stump height in cubic meter; dbh is the diameter in centimeter at a breast height of 1.3 meter; ln (dbh)² is natural logarithm of squared value of dbh; h is the total observed height of the tree in meter; h* is the modelled height from selected best height-diameter model (model h2) in this study; and a and b are parameters to be estimated; and v1, v2 and v3, are candidate volume models. evaluation criteria as mentioned in table 2 were tested for best fitted and validated volume equation. all parameter estimates of model v5 were only significant at 95% confidence interval among six candidate models (table 7). the r² values for all models ranged from 0.949 to 0.993. more than 94% of the variability in volumes were well described by all six models (adjusted r² > 0.949). models v2, v4, v5 and v6 showed somewhat similar and lower rmse values. biases for all models were lower than 0.0001 and were not considered for evaluation. the aic values for all models were comparatively very low. the volume equations were further subjected to graphical analysis of residual plots (figure 7) and scatter plots of predicted and observed volumes from given dbh (figure 8). the results from residual plot analysis showed models v4 and v5 performed well compared to other models. the analysis of observed and predicted volumes showed all models except v5 gave negative values of volume for some dbh. volume, sometimes cannot be explained by simple models that only utilize dbh or height. it can be justified as some growth models are useful only for certain height and diameter levels and cannot perform well in absence of attributes like stand density and site quality, which significantly affect height-diameter relationships (newton and amponsah, 2007; sharma and parton, 2007; sharma and yin zhang, 2004; sharma, 2009; temesgen and v. gadow, 2004). the height for model v5 was calculated from best height-diameter model h2 from this study. based on significance of parameter estimates as well as predicted values, model v5 was considered best model to estimate volume from given dbh and modelled height. the first model v1 is the simplest one using only dbh as independent variable. it was considered as local volume equation of teak in that particular area. the comparison of models utilizing measured height (models v1, v2, v3 and v4) with models using modelled height (models v5 and v6) showed somewhat similar results in terms of r² and adjusted r². using modelled height instead of actual observation can make measurement and prediction a lot easier. forest landowners can easily apply any models with only one variable to measure. koirala et al. /journal of tropical forestry and environment vol. 07, no. 01 (2017) 28-42 39 table 7: parameter estimates and validation criteria of the candidate models. model s parameter parameter estimate standard error r² adj. r² rmse bias aic v1 a¹ 0.4720 0.068 0.949 0.944 0.20 <0.00 01 1.16 b¹ 0.0414 0.002 v2 a 0.1192 0.104 0.992 0.990 0.08 <0.00 01 -20.68 b 0.0088 0.008 c¹ 0.0005 0.001 v3 a¹ 0.4544 0.133 0.959 0.951 0.18 <0.00 01 0.25 b¹ 0.0420 0.004 c 0.0021 0.014 v4 a 6.5e-02 7.4e-02 0.994 0.993 0.07 <0.00 01 -24.85 b 8.1e-03 4.9e-03 c¹ 2.5e-05 3.5e-06 v5 a¹ 0.3364 0.188 0.988 0.985 0.09 <0.00 01 -15.29 b¹ 0.0685 0.006 c¹ 0.0970 0.022 v6 a -1.6e-01 9.8e-02 0.991 0.989 0.08 <0.00 01 -20.01 b¹ 1.6e-02 6.6e-03 c¹ 1.9e-05 4.7e-06 ¹significant parameter values 4. limitations and scope of study the height-diameter equation and volume equations were developed for central lowland, nepal. the application of these equations in other places should be performed cautiously. less number of trees were felled for data analysis due to difficulties in destructive sampling. variables like quadratic mean diameter, stand basal area or trees per hectare and form factor were not included during model construction, which could be considered for future studies. such measures might possess complexity in data generation, model formulation and evaluation, but could yield stronger conclusion. 5. conclusions teak trees from an important part in plantation forest of lowland, nepal. four height-diameter relationship equations and six tree volume estimation equations were fitted in observed data from the study site. the equation utilizing natural logarithm of dbh (diameter at breast height) was considered to 40 be best model to predict height in terms of fitness and validation characteristics. similarly, the localized equation only using dbh to predict tree volume was selected for estimating volume of teak trees in sagarnath area, whereas the equation using dbh and modeled height from the best selected height-diameter equation was considered to be applicable generic model for volume estimation. we believe that these models would be appropriate to be used in lowlands of nepal and similar eco-region for teak species. acknowledgments this project was supported by funding from nifa -mcintire-stennis project me041621 and sagarnath forestry development project – students research grant. we would like to express our gratitude to bishnu hari wagle, assistant professor, institute of forestry, tribhuvan university and binod kumar singh, assistant forest officer, ilam, nepal, for their valuable suggestions during the initial part of the study. our appreciation goes to raj kumar rimal and elias ayrey for their support in spatial data generation and model formulation respectively. we are very grateful to dr. krishna poudel of oregon state university for reviewing initial phase of this manuscript. references basuki, t.m., van laake, p.e., skidmore, a.k., hussin, y.a., 2009. allometric equations for estimating the above-ground biomass in tropical lowland dipterocarp forests. for. ecol. manag. 257, 1684–1694. doi:10.1016/j.foreco.2009.01.027 baty, f., delignette-muller, m., 2015. tools for nonlinear regression analysis. r package. bi, h., hamilton, f., 1998. stem volume equations for native tree species in southern new south wales and victoria. aust. for. 61, 275–286. doi:10.1080/00049158.1998.10674752 budhathoki, c.b., lynch, t.b., guldin, j.m., 2008. a mixed-effects model for the dbh–height relationship of shortleaf pine (pinus echinata mill.). south. j. appl. for. 32, 5–11. calama, r., montero, g., 2004. interregional nonlinear height diameter model with random coefficients for stone pine in spain. can. j. for. res. 34, 150–163. chapman, d.g., 1961. statistical problems in dynamics of exploited fisheries populations, in: proc. 4th berkeley symp. on mathematics, statistics and probability. university of california press berkeley, pp. 153–168. chaturvedi, r.k., raghubanshi, a.s., 2015. allometric models for accurate estimation of aboveground biomass of teak in tropical dry forests of india. for. sci. 61, 938–949. doi:10.5849/forsci.14-190 coble, d.w., lee, y.-j., 2011. a mixed-effects height-diameter model for individual loblolly and slash pine trees in east texas. south. j. appl. for. 35, 12–17. cordero, l.d.p., kanninen, m., 2003. provisional equations for estimating total and merchantable volume of tectona grandis trees in costa rica. for. trees livelihoods 13, 345–359. doi:10.1080/14728028.2003.9752470 die, a., kitin, p., kouame, f.n., van den bulcke, j., van acker, j., beeckman, h., 2012. fluctuations of cambial activity in relation to precipitation result in annual rings and intra-annual growth zones of xylem and phloem in teak (tectona grandis) in ivory coast. ann. bot. 110, 861–873. doi:10.1093/aob/mcs145 fra/dfrs, 2014. terai forests of nepal (2010 2012). forest resource assessment nepal project/department of forest research and survey. gautam, s.k., thapa, h.b., 2007. volume equation for populus deltoides plantation in western terai of nepal. banko janakari 17, 70–73. koirala et al. /journal of tropical forestry and environment vol. 07, no. 01 (2017) 28-42 41 hansen, o.k., changtragoon, s., ponoy, b., kjær, e.d., minn, y., finkeldey, r., nielsen, k.b., graudal, l., 2015. genetic resources of teak (tectona grandis linn. f.)—strong genetic structure among natural populations. tree genet. genomes 11. doi:10.1007/s11295-014-0802-5 husch, b., beers, t.w., kershaw jr, j.a., 2002. forest mensuration, fourth edition. ed. john wiley & sons. jayaraman, k., zakrzewski, w.t., 2001. practical approaches to calibrating height–diameter relationships for natural sugar maple stands in ontario. for. ecol. manag. 148, 169–177. kaosa-ard, a., 1998. overview of problems in teak plantation establishment, in: teak for the future proceedings of the second regional seminar on teak. presented at the second regional seminar on teak, yangoon, myanmar, pp. 49–59. kizha, a., han, h.-s., 2016. predicting aboveground biomass in second growth coast redwood: comparing localized with generic allometric models. forests 7, 96. doi:10.3390/f7050096 lappi, j., 1997. a longitudinal analysis of height/diameter curves. for. sci. 43, 555–570. mandal, r.a., yadav, b.k.v., yadav, k.k., dutta, i.c., haque, s.m., 2013. development of allometric equation for biomass estimation of eucalyptus camaldulensis: a study from sagarnath forest, nepal. int j biodiv ecosyst 1, 1–7. mugasha, w.a., mwakalukwa, e.e., luoga, e., malimbwi, r.e., zahabu, e., silayo, d.s., sola, g., crete, p., henry, m., kashindye, a., 2016. allometric models for estimating tree volume and aboveground biomass in lowland forests of tanzania. int. j. for. res. 1–13. doi:10.1155/2016/8076271 newton, p.f., amponsah, i.g., 2007. comparative evaluation of five height–diameter models developed for black spruce and jack pine stand-types in terms of goodness-of-fit, lack-of-fit and predictive ability. for. ecol. manag. 247, 149–166. doi:10.1016/j.foreco.2007.04.029 parresol, b.r., 1999. assessing tree and stand biomass: a review with examples and critical comparisons. for. sci. 45, 573–593. peng, c., zhang, l., liu, j., 2001. developing and validating nonlinear height–diameter models for major tree species of ontario’s boreal forests. north. j. appl. for. 18, 87–94. perez, d., 2008. growth and volume equations developed from stem analysis for tectona grandis in costa rica. j. trop. for. sci. 20, 66–75. r core team, 2016. r: a language and environment for statistical computing. r foundation for statistical computing, vienna, austria. richards, f.j., 1959. a flexible growth function for empirical use. j. exp. bot. 10, 290–301. sandeep, s., m. sivaram, henry, m., birigazzi, l., 2014. inventory of volume and biomass tree allometric equations for south asia. un-redd programme, india. sharma, m., parton, j., 2007. height–diameter equations for boreal tree species in ontario using a mixed-effects modeling approach. for. ecol. manag. 249, 187–198. doi:10.1016/j.foreco.2007.05.006 sharma, m., yin zhang, s., 2004. height–diameter models using stand characteristics for pinus banksiana and picea mariana. scand. j. for. res. 19, 442–451. doi:10.1080/02827580410030163 42 sharma, r.p., 2009. modelling height-diameter relationship for chir pine trees. banko janakari 19, 3–9. doi:10.3126/banko.v19i2.2978 spruge, d.g., 1983. correcting for bais in log transformed allometric equations. ecology 64, 209–210. temesgen, h., v. gadow, k., 2004. generalized height–diameter models—an application for major tree species in complex stands of interior british columbia. eur. j. for. res. 123, 45–51. doi:10.1007/s10342-004-0020-z tewari, v.p., mariswamy, k.m., 2013. heartwood, sapwood and bark content of teak trees grown in karnataka, india. j. for. res. 24, 721–725. doi:10.1007/s11676-013-0410-5 tewari, v.p., mariswamy, k.m., arunkumar, a.n., 2013. total and merchantable volume equations for tectona grandis linn. f. plantations in karnataka, india. j. sustain. for. 32, 213–229. doi:10.1080/10549811.2013.762187 thapa, h.b., gautam, s.k., 2007. growth performance of tectona grandis linn f. between two thinning operations at shankarnagar, western terai, nepal. banko janakari 17, 11–17. doi:http://dx.doi.org/10.3126/banko.v17i2.2151 thapa, h.b., gautam, s.k., 2005. growth performance of tectona grandis in the western terai of nepal. banko janakari 15, 6–12. doi:http://dx.doi.org/10.3126/banko.v15i2.344 trincado, g., burkhart, h.e., 2006. a generalized approach for modeling and localizing stem profile curves. for. sci. 52, 670–682. wagle, b.h., sharma, r.p., 2012. modelling individual tree basal area growth of blue pine (pinus wallichiana) for mustang district in nepal. for. sci. technol. 8, 21–27. doi:10.1080/21580103.2012.658236 weiskittel, a.r., hann, d.w., kershaw jr, j.a., vanclay, j.k., 2011. forest growth and yield modeling, first edition. ed. john wiley & sons. zahabu, e., raphael, t., chamshama, s.a.o., iddi, s., malimbwi, r.e., 2015. effect of spacing regimes on growth, yield, and wood properties of tectona grandis at longuza forest plantation, tanzania. int. j. for. res. 2015, 1–6. doi:10.1155/2015/469760 zeide, b., 1993. analysis of growth equations. for. sci. 39, 594–616. microsoft word jayaweera feature jayaweera et al., /journal of tropical forestry and environment vol. 2, no. 02 (2012) 1-12 1 feature article are green jobs sustainable for sri lankan economy? m. jayaweera *1 , j. manatunge 1 and a. witharana 1 department of civil engineering, university of moratuwa, moratuwa, sri lanka 1. introduction it is imperative that sri lanka grasps the concepts of green jobs to meet the most vital but intricate challenge of the 21 st century, which is the transformation to a sustainable and a low-carbon economy. such a transformation or a paradigm shift, which can be gradual or rapid depending on the circumstances, will undoubtedly have a considerable positive effect on the way we produce and/or consume goods and services. the speed at which this transformation would occur is likely to accelerate in the near future as there is a trend of global transition from a traditional to a low-carbon economy, in order to attain sustainable economies. such trends will help create an array of different forms of green jobs across many sectors, and most probably can become a catalyst for further development. the international labour organization (ilo) has defined green jobs as “jobs created when they help in reducing the negative environmental impacts ultimately leading to environmentally, economically and socially sustainable enterprises and economies”. green jobs, in general, stand on two pillars: decent work and environmental sustainability. thus, green jobs can be defined as decent work that contributes to environmental sustainability. in a broader sense decent work needs to address the core of international labour standards such as freedom of association and effective recognition of the right to collective bargaining, elimination of all forms of forced or compulsory labour, effective abolition of child labour, elimination of discrimination in respect of employment and occupation, occupational health and safety, etc. whilst aligning to laws applicable to sri lanka. environmental sustainability addresses issues such as effectively combating climate change, pollution prevention and control, conservation of eco-systems and biodiversity etc. (ilo, 2007). 2. survey on green job green job surveys have been done by institutions in different countries such as malaysia, bangladesh, australia, usa and elsewhere (unep, 2008). however, there is no comprehensive study undertaken up to now in order to find out the status of green jobs in practice in sri lanka. the main purpose of this green job survey in sri lanka was therefore to explore the role of organizations in three sectors (agriculture, industry and services) in contributing towards green jobs opportunities while emphasizing on the importance of decent work. it was done by formulating a questionnaire and sending it to the membership of the efc (employers’ federation of ceylon). fifty organizations responded to this questionnaire from which information and data were gathered to prepare this paper. this questionnaire specifically included the two main aspects of green jobs, viz., environmental sustainability and decent work. environmental sustainability encompasses the attributes such as power utilization and related data, application of 3r principle (reduce, recycle and reuse potentials) in waste reduction, use of technologies that need less energy, raw material and other resources, proper house *correspondence: mahesh@civil.mrt.ac.lk tel: +94-011-2650567, fax: +94-11-2651216 issn 2235-9370 print / issn 2235-9362 online ©2012 university of sri jayewardenepura jayaweera et al., /journal of tropical forestry and environment vol. 2, no. 02 (2012) 1-12 2 keeping with cleaner production opportunities, potential for energy saving, reduction of greenhouse gases, reduction potential for fossil fuel usage, waste management and pollution reduction, ecosystem conservation etc., whereas decent work includes attributes such as wages, career prospects, job security, occupational health and safety as well as other working conditions, respectively. the questionnaire was reviewed and updated with comments and information given by relevant authorities before finalization, which were then distributed to target organizations through efc. in this survey, the private sector represents 92 per cent (28 private limited companies and 15 public limited companies) out of 50 organizations surveyed. government sector contribution is about 6 per cent representing only three entities. as indicated by economic and social statistics of sri lanka (2011) published by the central bank of sri lanka, contribution to the gdp by each sector was reckoned to be as follows: agriculture 11.9 per cent, industry 28.9 per cent and services 57.3 per cent. nevertheless, the organizations participated constituted 17 per cent in agriculture, 40 per cent in industry and 43 per cent in services sectors, respectively. 3. environmental sustainability towards sri lankan economy through the concept of green jobs the attributes that were considered in the survey to be pertinent for sri lankan economy are renewable energy, energy efficiency, green buildings and construction, conservation of natural resources including water, fisheries etc. forestry, afforestation/reforestation, environmentally friendly agriculture (pesticides free, water efficient, etc), clean transportation and fuels, mass transit, pollution prevention and control in manufacturing including cleaner production and good house-keeping and clean-up operations. 3.1. renewable energy due to the geo-climatic conditions, sri lanka is blessed with several forms of renewable energy resources. some of them are widely used and developed to meet the energy demand of the country while others have the potential for development when technologies become feasible and economically viable for use. however, renewable energy has become one of the key areas in which about 5 per cent have made a positive change in this survey. 3.1.1. hydropower the hydroelectricity potential of the country has already been exploited to a major extent, a source that delivers comparatively low-cost electricity. apart from the grid connected hydro power stations, there are small-scale hydro-power applications (mini and micro) in operation serving off-grid loads. according to the survey, off-grid electricity generation by using hydropower is dominated by the agriculture sector (10 organizations). this is mainly because of the fact that most of the organizations operating under agriculture sector are involved in tea production. the geo-climatic settings of the tea plantations are particularly conducive to harnessing hydro resources due to high rainfall in hilly areas throughout the year. in addition, there are two manufacturing entities that are involved in hydropower generation. similarly, direct use of hydropower is also associated with the agriculture sector organizations as they produce electricity either by micro or mini hydropower plants. 3.1.2. biomass large quantities of firewood and other biomass resources such as agriculture residues are used for cooking in rural households, despite the fact that they have access to grid electricity (sri lanka sustainable energy authority, 2007). however, in the industry context, use of biomass to generate energy is somewhat lacking (only 2 organizations). though biomass is a feasible option to produce energy, still more efforts are needed to convince the organizations to switch to biomass operated systems for their steam or electricity requirements. though there is a huge potential for biomass energy particularly for the generation of electricity, supply of substrate material especially in the form of dendro-wood would be the jayaweera et al., /journal of tropical forestry and environment vol. 2, no. 02 (2012) 1-12 3 main bottleneck as huge quantities (e.g., 1,000 acres for 1 mw power production) are required. sri lanka does not have such large extents of land set aside exclusively for growing such plants (eg. gliricidia sepium) but there are lands on which intercropping is possible. 3.1.3. solar energy solar energy is derived from solar radiation that has applications in space heating and cooling through solar architecture, day lighting, heating water, cooking, and high temperature processed heat for industrial purposes. as estimated in the solar resource map developed by the national renewable energy laboratory (nrel) of the usa, over most parts of the flat dry zone in sri lanka, which accounts for two-thirds of the land area, solar radiation varies from 4.0 – 4.5 kwh/m 2 .day. electricity generation using solar energy requires large areas (e.g., 40 acres per mw). however, the production of solar energy in the form of electricity seems to be lacking as this technology is reckoned to be comparatively expensive. it was evident from this survey too, that there are only 3 organizations (from each sector) who are involved in generating electricity using solar energy. in contrast, some are already engaged in utilizing energy in the form of electricity and more frequently hot water from solar panels. this trend seems to be on the rise as they may have understood the importance of reducing the use of fossil fuels for different activities. surprisingly, some have thought of the ‘net metering’ concept where during day time electricity generated by solar panels will be utilized by the organization itself but during nighttime it will be connected to the grid so that what is stored in excess will be supplied to someone else. however, realization of such schemes may take some time and formal campaigns are of paramount importance in order to encourage organizations in the long run. 3.1.4. wind energy wind airflows can be used to run wind turbines thereby generating electricity. the power output of a turbine is a function of the cube of the wind speed, so as wind speed increases, power output increases dramatically. areas where winds are stronger and more constant, such as offshore and high altitude sites are preferred locations for wind farms. according to the wind energy resource atlas of sri lanka developed by national renewable energy laboratory (nrel) of the united states, there are nearly 5,000 km 2 of windy areas with good-to-excellent wind resource potential in sri lanka. about 4,100 km 2 of the total windy area is land and about 700 km 2 is lagoon areas. the windy land represents about 6 per cent of the total land area of sri lanka. using a conservative assumption of 5 mw per km 2 , this windy land could support almost 20,000 mw of potential installed capacity. use of wind energy is also at a very poor level (only two organizations from the industry sector). this is probably due to the fact that the capital investment associated with wind energy is rather high and it requires substantial square kilometers of land. 3.2. energy efficiency measure it is remarkable to note that most organizations (about 30 organizations) those participated in this survey have paid great attention to energy efficiency measures. this improvement in the energy sector is partially attributable to the training and education on energy conservation and management, coordinating energy management activities through energy managers, introducing energy efficiency guidelines for building construction etc. it was also noted that organizations have had direct benefits by saving energy costs through improvement of efficiencies. 3.2.1. energy audit energy audit is commonly used to describe a broad spectrum of energy studies ranging from a quick walk-through of a facility to identify major problem areas to a comprehensive analysis of the implications of alternative energy efficiency measures sufficient to satisfy the financial criteria of sophisticated interventions. it provides energy solutions for saving the energy bill, improving energy efficiency by capturing energy wastages and to meet the demands of the green economy. there are about jayaweera et al., /journal of tropical forestry and environment vol. 2, no. 02 (2012) 1-12 4 21 organizations those who have already got this audit done and have been enjoying reduced electricity bills by 10-20 per cent of energy savings. 3.2.2. good housekeeping housekeeping is one of the low cost/no cost for energy conservation opportunities which can be defined as an excellent starting point for improving the operations or day to day work. it is interesting to observe that most of the organizations (about 30) engaged in this survey have paid their attention to saving energy and/or increasing energy efficiency by means of good housekeeping measures. these measures can help save energy, reduce the cost of production and at the same time minimize losses of raw materials, minimize waste, conserve water and mitigate environmental impacts indicating a set of benefits. 3.3. green buildings green building design and construction is the opportunity to use natural resources more efficiently, while creating healthier environment, balancing energy-efficient, cost-effective and lowmaintenance products for construction needs. the green building council of sri lanka (gbcsl) launched in november 2009 commits to developing a sustainable building industry for sri lanka. it will provide the necessary advice and know-how in the efforts of making buildings green. however, there were some organizations that have already received leed certification from the u.s. green building council. there are about 7 manufacturing industries and two entities from the service sector that have already been involved in green building construction practices. it is clear that the manufacturing sector is mainly involved in indoor climate control interventions as they directly benefit from such interventions particularly with the creation of a healthy environment to work comfortably within the factory premises. these scenarios undoubtedly increase the productivity and leads to gaining higher profit margins. 3.4. water conservation water conservation is relatively high in the industry sector as they consume a considerable amount of water for their industrial processes and also for cleaning up operations. in the agriculture sector, though watering is an essential component, many organizations now rely on rainwater. however, there are 8 organizations that employ water conservation practices in the agriculture sector. there are 13 organizations from the industry sector who are involved in different water conservation methods. unfortunately, the service sector (only 2 organizations) has not paid much attention to water conservation as it does not impact their day-to-day operations. water conservation is also inhibited by the lower prices that water board has in offer and they do not reflect real production costs. 3.4.1. rainwater harvesting rainwater harvesting (rwh) is a technique of arresting rainwater when it falls on to a shelter and storing it for subsequent use. harvested rainwater can be utilized for several purposes including drinking, washing, gardening, etc. the national policy on rain water harvesting in sri lanka was officially launched on september 27, 2005. the main objective of the national rwh policy is to ensure that the potential ‘cities of tomorrow’ apply rainwater harvesting broadly by the control of water near its source, in its pursuance of becoming ‘green cities’ in the future. thus the demand on the water sources will be minimal if part or whole of the rainwater is utilized in an effective manner. though rainwater harvesting is a good gesture to start off in conserving water, there are only 12 organizations who have taken an active part in such initiatives. 3.4.2. wastewater reclamation/recycling recycling of wastewater has become an important aspect of water resources and environmental management policies. it ensures reliable alternative water resources, reduces pollution and achieves a jayaweera et al., /journal of tropical forestry and environment vol. 2, no. 02 (2012) 1-12 5 more sustainable form of development. there are 12 organizations who have thought of it but implementation aspects seem to be poor yet. 3.5. reuse/recycling of raw materials ‘reduce’, ‘reuse’, and ‘recycle’ of materials are commonly known as the 3r principle. the ‘reduce’ in 3r means the reduction of the amount of waste and rubbish produced by the organization. reuse is the ability to use them once again may be for some other process or even for the same processes. recycling is an array of processing by which used materials (waste) are converted to new products to prevent waste of potentially useful materials, reduce the consumption of fresh raw materials, reduce energy usage, and lower greenhouse gas emissions as compared to virgin production. there are iso standards related to recycling such as iso 15270:2008 for plastic waste and iso 14001:2004 for environmental management control of recycling practice. in particular, the industry sector (15 organizations) and agriculture sector (9 organizations) are very keen on the 3r principle as it yields direct benefits to them. in service sector, there are 11 organizations involved in recycling/reuse of raw materials. 3.6. reforestation reforestation is the natural or intentional restocking of existing forests and or woodlands that have been depleted, usually through deforestation. reforestation can be used to improve the quality of human life by soaking up pollution and dust from the air, rebuild natural habitats and ecosystems thereby minimizing the global warming. in forestry related activities it is apparent that organizations that are in the agriculture sector (9 organizations) have directly contributed to reforestation, afforestation, conservation of biodiversity, as it is part of their business. however contribution from industry sector (4 organizations) and services sector (3 organizations) are relatively low. 3.7. green transport this refers to any means of transport with relatively insignificant adverse impacts on the environment, and includes walking and cycling, group transportation, mass transportation, pooling of vehicles, scheduled supply chain etc. while protecting urban transport systems that are fuel-efficient, space-saving and also promoting healthy lifestyles. improving efficiency of a vehicle reduces its fuel consumption and emissions to atmosphere. a range of novel technologies and approaches would help create cleaner, more efficient vehicles, including light weight materials, advanced transmissions, batterydirect etc. there were quite a number of organizations (20 organizations) found involved in some of these schemes helping to reduce adverse impacts, particularly in relation to air pollution. 3.8. control and prevention of pollution in an attempt to abate the scenarios of pollution, the amounts of pollutants generated were not quantified by most organizations. there are considerable numbers of organizations (16 organizations) producing industrial wastewater and employ different wastewater treatment methods prior to discharge the effluents to the environment. however, sustainability of such technologies is questionable as hardly any 3r principles are applied. therefore, it is imperative to note that pollution prevention efforts need to pay more attention on environmentally friendly and sustainable practices. 3.8.1. air quality air pollution is a change in the physical, chemical and biological characteristics of air that causes adverse effects on humans and other organisms. however, in the present survey, the amount of pollutants generated was not quantified. however the types of air pollutants emanated by organizations and their mitigation techniques were recorded. only a very few organization (8 organizations) have an idea of what jayaweera et al., /journal of tropical forestry and environment vol. 2, no. 02 (2012) 1-12 6 types of pollutants that they emit into atmosphere as a result of their business activities. awareness campaigns are therefore of utmost importance. 3.8.2. wastewater the main sources of water pollution are domestic, urban and municipal wastes (including both sewerage and solid waste), agro-chemicals (such as pesticides, fertilizers and herbicides), industrial effluents (including chemicals, detergents, heavy metals and oils) and marine and shipping waste (including oil spills, chemicals and ballast water) etc. there are separate standards that have been set for potable water (drinking water) and effluents (wastewaters that are discharged from industries and sewerage treatment plants). the standards for effluent discharge into water sources have been defined in relation to the specific places of discharge (irrigation land, marine and coastal areas, surface waters), types of effluents (domestic or industrial), and type of industry (rubber, textiles, tanning, palm oil and coconut kernel etc). any standard for a specific industry overrides the general standards. in this survey, it was seen that some organizations (about 16 organizations) produce industrial wastewater and they employ different wastewater treatment methods prior to discharge to the environment. 3.8.3. hazardous waste hazardous waste is waste material that is reactive, toxic, corrosive or otherwise poses a hazard to human health and environment. hazardous waste needs special collection and disposal. toxic and hazardous waste is generated mainly in the industrial and medical sectors and is being generated in increased quantities. hazardous waste includes heavy metals, oil, agrochemicals, paints, varnish and asbestos waste etc. thirteen organizations are found to generate hazardous materials and employ different methods of management. some hand the waste over to a competent entity capable of handling and processing the hazardous waste at a price, however, there are others who are clueless of safe disposal methods. hence it is apparent that handling hazardous waste is also an appropriate topic on which training must be organized. 4. decent work for sri lankan economy through the concept of green jobs the definition of green jobs focuses not only on the environmental aspects of a job. green jobs also need to be decent jobs with concerns including wages, career prospects, job security, occupational health and safety as well as other working conditions. people’s livelihoods, rights, and sense of dignity are integral to their jobs; jobs need to provide equal hope for the environment and the jobholder. a job which is exploitative or harmful, or fails to pay a living wage cannot be called ‘green’. preferably, the future of employment will be more respectful and protective while caring for the natural environment and workers’ health, basic needs, and rights of employees. in this survey, environmental policy, hr/hrd policy, policy for disabled, gender equity policy, policy for hiv/aids etc. were considered as policies in existence in order to support employees. in addition, transport, medical, overtime, maternity, worker participation in decision making, equal opportunity employment, procedure for grievances/and arbitration are also included. 4.1. environmental policy environmental policy is any action deliberately taken to manage human activities with a view to preventing, reducing or mitigating harmful effects on nature and natural resources, and ensuring that human intervention to the environment does not have any harmful effects on the community. in this survey, however, the adoption of environmental policies in each sector (agriculture 6 organizations, industry-7 organizations and services-6 organizations) is relatively low. nevertheless, some of the organizations have already ratified internationally recognized sustainability standards, which are considered essential requirements of an environment related policy. jayaweera et al., /journal of tropical forestry and environment vol. 2, no. 02 (2012) 1-12 7 4.2. human resource policies human resource policies are systems of codified decisions, established by an organization, to support administrative personnel functions, performance management, employee relations and resource planning. each organization has a different set of circumstances, and based on them, develops an individual set of human resource policies. almost all organizations (44 organizations) have a written policy on human resource management. 4.3. gender equality policy the international definition of gender equality is “that all human beings are free to develop their personal abilities and make choices without the limitations set by strict gender roles; that the different behavior, aspirations and needs of women and men are equally considered, valued and favored”. the implementation of such a policy is relatively a low priority (only 11 organizations) as most of the organizations mentioned that they do care about the worker’s potential and capability to work regardless of gender alluding to a gender neutral approach in the workplace. 4.4. hiv/aids policy hiv/aids is a major development crisis that affects all sectors. during the last two decades the hiv/aids epidemic has spread relentlessly affecting people in all walks of life and decimating the most productive segments of the population particularly women and men between the ages of 20 and 49 years. in this present survey only 8 responses were recorded. 4.5. worker’s welfare policy welfare includes anything that is done for the comfort and improvement of employees and is provided over and above the wages, but not as a matter of right. welfare helps in keeping the morale and motivation of the employees high so as to retain the employees for longer duration. employee welfare includes addressing challenges in working conditions, creation of industrial harmony through infrastructure for health, industrial relations and insurance against disease, accident and unemployment for the workers and their families. there are about 20 organizations that have come up with welfare policies and the managements of these organizations have such policies and employees are benefitting from it. 4.6. epf/etf all the organizations (50) engaged in this survey have contributed to these schemes which are a statutory requirement. 4.7. career development opportunity career development opportunity seems to be very prominent in each sector as 10 organizations from agriculture sector, 20 organizations from industry sector and 19 organizations from services sector are offering career development opportunities for their employees. 4.8. life and health insurance life and health insurance becomes vital as such schemes may help to facilitate proper health care for the employees. 44 organizations have implemented such schemes successfully. 4.9. profit sharing scheme sharing of profits among the workers seems to be quite low as 20 organizations from all sectors have introduced such schemes to the employees. jayaweera et al., /journal of tropical forestry and environment vol. 2, no. 02 (2012) 1-12 8 4.10. bonus scheme bonus schemes seem to be quite popular as 10 organizations from agriculture sector, 17 organizations from industry sector, and 17 organizations from services sector are involved in bonus schemes. 5. gaps in green jobs: sri lankan context this analysis highlights the existing practices of green jobs and deficits in the above-mentioned sectors that included 50 organizations that provided information related to green jobs. the two pillars of green jobs were considered when analyzing the gaps, viz., environmental sustainability and decent work. a number of issues in this context were raised and following is the list of issues raised and questions set in to gather more information. question 1: does your business or organization currently have any green jobs initiatives? this question was raised to gather current information on any green jobs initiatives that the organization has already initiated, and/or planning to initiate. out of the 50 local organizations participated in the survey, only 14 indicated that their businesses have ‘green’ jobs initiatives; the rest either skipped the question without answering by leaving the section blank or stated ’no’. nevertheless, some organizations in the industry sector seemed to have well-understood the green concept and even have achieved international sustainable standards. it is encouraging to note that some organizations in the agriculture sectors have already initiated and incorporated green culture into their business strategies. at the same time, it is disappointing to note that the services sector is far behind in green job initiatives and implementing sustainability initiatives. question 2: what do you think is preventing your organization (or in being less committed to) in implementing green initiatives? this question was raised to identify any constraints in implementing any green imitative(s). for the majority, the cost factor seemed to be the highest concern in implementing green job initiatives and adopting green technologies. in addition, the longer period for return on investments, lack of skilled staff and knowledge etc. were also identified. some organizations in the industry sector have taken the lead in making the jobs greener and taken the leadership of ‘going green’. the services sector, on the contrary, were lagging behind in adopting green practices assuming that green business is something that is not related to their day-to-day activities that they are involved in. question 3: what factors (green jobs related) do limit the growth of your business? please comment on what you feel can be done at the national policy level to assist growth in this sector. this question was raised to identify limitation of the growth of business activities that can be directly related to any green job-related factors. the organizations who took part in the survey believe that national level policies need to be strengthened and/or implemented in order to help and assist organizations to move forward in the environment friendly business concepts and policies to compensate them and also provide incentives for organizations which have already implemented green initiatives. national level policies are also needed to concentrate more on environmentally friendly alternatives for energy generation (electricity), by so ensuring that the organizations that opt for such greener options and the country as a whole will be benefitted in the long run. moreover, at the national policy level, green jobs must be an integral part of the routine day-to-day activities, standardized policies and practices with objective parameters to gauge the performance and a periodic evaluation to measure the performance, and a rating system to recognize star performers. jayaweera et al., /journal of tropical forestry and environment vol. 2, no. 02 (2012) 1-12 9 question 4: what do you think is the best strength of your organization in implementing green job initiatives? this question was raised to identify positive attributes of an organization for successful implementation of green job initiatives. the organizations operating at a large scale, especially in the industry and agriculture sectors are moving onto more environmentally friendly technologies and sustainability and green initiatives because such plans may open up with opportunities that are competitively advantageous for them. moreover, some tools like lean manufacturing have increased the efficiency and productivity of the manufacturing processes. the commitment of top management is indicated as the best strength in these organizations in implementing green job initiatives. the gap analysis manifested that most job positions require ‘on the job training’ to enhance ‘soft skills’ and basic skills but do not necessarily require advanced green knowledge. the soft skills essentially uplift dependability and reliability, initiative, and interpersonal skills of employees. green knowledge is more important for managers and small business owners who establish ‘green’ procedures and provide ‘on the job training’ for their employees. hence the component of training particularly on decent work at different levels is of utmost importance for the establishment of green jobs in sri lanka. nevertheless, it is apparent from this study that the present status of green jobs in sri lanka is less impressive, hence a series of gaps have to be addressed. although certain organizations have embraced environmental technologies that are reckoned to be green, adoption of decent work conditions among their employees is questionable. this may be due to the fact that sustainable technologies pay them back tangible benefits in a comparatively shorter period of time but the benefits from decent work seem to be intangible. this disparity could be rectified through well-structured awareness programmes for all levels of employees thereby creating a healthy bank of green jobs. 6. training needs for effective green jobs having analyzed the questionnaires it was evident that sri lankan organizations need comprehensive training packages in order to create green jobs in their respective sectors. as the green job concept as a business case is rather new to sri lanka organizations have not initiated necessary action to implement the green jobs. sustainable enterprises and industries would be the key to survival with ever increasing fossil fuel prices and in this context adoption of green jobs would be an added advantage hence it is of paramount importance to move towards a green job culture even now. to implement sustainable enterprises and industries effectively, employees must be trained at every level of their hierarchy. at present new frontier technologies that are reckoned to be green are imperative for well-performing enterprises. when interviewed, it was clear that most of them showed reluctance in adopting new green technology as they were not fully informed of its positive impact on the enterprise. a formally developed well-structured course on green jobs is therefore essential in order to fill the knowledge and technical skills gap. 6.1. level of training needed for effective green jobs positive attitudes towards effective green jobs by top-management are of utmost importance and their initiatives are essential to initiate the creation of green jobs. however knowledge on green jobs by the top-management seems to be varied but there remain misconceptions. hence a workshop for the top management would help resolve these issues and their mindset could be adjusted in a positive manner so that greener jobs could be created within enterprises and industries. at the middle level, employees were found to contribute much in various ways to decision making on creating green business but their knowhow seems insufficient due to a lack of formal training. there were a few middle level employees who have received foreign training and a few others who have received training locally. jayaweera et al., /journal of tropical forestry and environment vol. 2, no. 02 (2012) 1-12 10 table 1: contribution by sectors for different attributes of green jobs number of organizations agriculture industry services total 12 28 10 50 attribute number % of total number % of total number % of total number % of total environmental sustainability renewable energy hydro 10 20% 2 4% 0 0% 12 24% biomass 1 2% 1 2% 0 0% 2 4% wind 0 0% 2 4% 0 0% 2 4% solar 1 2% 1 2% 1 2% 3 6% energy efficiency 8 16% 18 36% 4 8% 30 60% energy audit 5 10% 13 26% 4 8% 22 44% good house keeping 5 10% 13 26% 7 14% 25 50% green buildings 2 4% 7 14% 5 10% 14 28% water conservation 8 16% 13 26% 2 4% 23 46% recycling of raw materials 9 18% 15 30% 11 22% 35 70% reforestation 9 18% 4 8% 3 6% 16 32% green transportation 2 4% 13 26% 5 10% 20 40% control and prevention of pollution air quality 0 0% 6 12% 2 4% 8 16% wastewater 2 4% 10 20% 4 8% 16 32% hazardous waste 2 4% 8 16% 3 6% 13 26% decent work environment policy 6 12% 7 14% 6 12% 19 38% hr policy 10 20% 15 30% 19 38% 44 88% gender equity 8 16% 11 22% 9 18% 28 56% hiv/aids policy 2 4% 2 4% 4 8% 8 16% workers welfare policy 10 20% 18 36% 19 38% 47 94% epf/etf 12 24% 19 38% 19 38% 50 100% career development 10 20% 20 40% 19 38% 49 98% life & health insurance 9 18% 19 38% 16 32% 44 88% profit sharing scheme 8 16% 5 10% 7 14% 20 40% bonus scheme 10 20% 17 34% 17 34% 44 88% jayaweera et al., /journal of tropical forestry and environment vol. 2, no. 02 (2012) 1-12 11 7. conclusions though efc has a large number of members (about 500) only 50 members responded to the questionnaire. the questionnaire consisted of two main sections namely sustainable green technologies and initiatives and decent work, respectively. the table 1 summarized the contribution of each sector for different attributes of green jobs. in this survey, in terms of environmental sustainability, the contribution from industry sector is relatively high with compared to agriculture and services sectors (table 1). however, some essential components of environmental sustainability such as switching to renewable energy (biomass, solar) are rather low. measures to increase energy efficiency in terms of energy audits and/or good housekeeping seem to be attractive for every sector as it significantly reduces the cost of electricity. thus green building concept has been recently popularized among organizations with involvement of 28 per cent in all sectors. water conservation among organizations needs to be increased as water resources become scarce. recycling of raw materials (e.g., paper) is practiced widely and total contribution is about 70 per cent for all sectors. the decent work component seems to be relatively strong in terms of statutory attributes such as epf/etf, health and safety issues, maternity and overtime provisions. in addition, some other benefits such as transport, insurance and bonus schemes are also provided for employees though they are not statutory requirements. it is interesting to note that career development is considered important by almost all organizations. however, some essential attributes pertaining to decent work such as having a policy for hiv.aids, gender equity are still lacking. moreover, according to the ilo definition, some essential components of decent work such as freedom of association, abolition of forced or compulsory labour, elimination of discrimination in respect of employment and occupation etc. could not be grasped properly through the questionnaire. in order to see a positive growth in green jobs, organizations must foresee the benefits of green jobs and they should explore the possibility of moving towards becoming greener businesses by catering to green needs and opportunities. in summary it is apparent that most of the organizations stick to the mandatory attributes with great success but other attributes that are of paramount for green jobs are yet to be embraced at large. at least a few of these organizations have perceived the importance of green jobs in the context of retention of good work force among them. in future what remains within the sustainable economy reflects a large number of green jobs creations through practices of more and more environmental sustainable initiatives with decent work embedded in them. 7. recommendations initially, data that have been collected would be published for the purpose of dissemination so that there is better access to the findings of this study. secondly, to create a database within the efc from which the membership could make referrals for advice, and services in relation to green jobs, concerted efforts should be taken collectively by all stakeholders. it is also recommended that a monitoring mechanism to facilitate and support greening jobs within the efc membership is established through efc’s green team with technical support from the ilo. a green jobs policy and a set of guidelines on green jobs for organizations are recommended to ensure sustainability for and amongst relevant stakeholders. finally, a database on the types of green jobs in sri lanka could be prepared by efc to be distributed among enterprises and industries to facilitate a just transition through sharing of knowledge and exchange of information. jayaweera et al., /journal of tropical forestry and environment vol. 2, no. 02 (2012) 1-12 12 acknowledgements we wish to thank mrs. shyama salgado, ilo representative, for all the assistance and encouragement given to us in conducting this survey and the efc green team headed by ms. thamali senanayake for all their efforts in bringing about a successful completion of a survey on “green jobs” amongst employers in sri lanka. references bulletin of labour force statistics of sri lanka, department of census & statistics, issue no.55, issn 13913050, department of census & statistics, colombo. central bank of sri lanka, 2011, economic and social statistics of sri lanka, isbn 978 955 575 212 – 1, central bank of sri lanka, colombo. green building council sri lanka, 2010, greensl® rating system for built environment. green building council, sri lanka. international labour organization, 2007, international labour conference on conclusions concerning the promotion of sustainable enterprises, isbn 978-92-2-120131-1 (print), isbn 978-92-2-120132-8 (web pdf), international labour office, geneva. judges and environmental law, a handbook for sri lankan judiciary, 2009, isbn 978-955-8302-03-3. environmental foundation limited, sri lanka. ministry of environment, 2011, national green reporting system of sri lanka, reporting guidelines, ministry of environment, sri lanka. sri lanka sustainable energy authority, 2007, sri lanka energy balance: an analysis of energy sector performance, sri lanka sustainable energy authority, sri lanka. united nations environment programme, 2008, green jobs: towards decent work in a sustainable, lowcarbon world, isbn: 978-92-807-2940-5. united nations environment programme (unep), nairobi. chapter 2 14 toxicity of neem leaf extracts (azadirachta indica a. juss) on some haematological, ionoregulatory, biochemical and enzymological parameters of indian major carp, cirrhinus mrigala m. saravanan1, m. ramesh*1, a. malarvizhi1 and r. petkam2 1 unit of toxicology, department of zoology, school of life sciences, bharathiar university, coimbatore-641 046, tamil nadu, india. 2 department of fisheries, faculty of agriculture, khon kaen university, khon kaen-40002, thailand. date received: 25-06-2011 date accepted: 10-09-2011 abstract in the present study, the median lethal concentration (lc 50) of neem leaf extract to cirrhinus mrigala for 24 h was found to be 1.035 g l-l. during the study period, the haematological parameters including hb, hct, rbc, mcv, mch and mchc levels were significantly decreased in neem leaf extract exposed fish when compared to the control fish whereas wbc count was increased. similarly, plasma na+ and cllevels were significantly lower and k+ level were significantly higher when compared to the control. in biochemical study, elevated plasma glucose and induced protein levels were noticed. the enzymes, glutamate oxaloacetate transaminase (got) and glutamate pyruvate transaminase (gpt) activities were increased significantly in gill, liver and muscle of treated fish compared to that of their control groups. the results of the present investigation suggest that neem leaf extracts affects the hematological, ionoregulatory, biochemical and enzymological parameters of fish and alterations of these parameters can be useful in environmental biomonitoring of neem based products in freshwater environment. keywords: azadirachta indica, acute toxicity, cirrhinus mrigala, haematology, ion regulation, biochemical and enzymological parameters. *correspondence: e-mail-mathanramesh@yahoo.com, tel-+91-422-2428394, fax-+91-422-2422387, issn 2235-9370 print/ issn 2235-9362 online ©2011 university of sri jayewardenepura journal of tropical forestry and environment vol. 01, no. 01 (2011) 14-26 15 1. introduction many studies illustrated that neem (azadirachta indica) extract has widely used in controlling of insect pests (kreutzweiser et al., 2004). the water soluble part of neem based extracts possess hypoglycemic, hypolipidemic, anti-inflammatory, hepatoprotective, antifertility activities and used as a chemo preventive agent in different parts of the world (chattopadhyay et al.,, 1993). recently the use of medicinal plants particularly neem based products as alternatives of synthetic pesticides has gained importance and extensively used in aquaculture to control fish predators and pathogens (martinez, 2002; tiwari and singh, 2003; winkaler et al., 2007). the widely used neem based biopesticides directly enter into the various water resources such as streams, river, and lakes, and may affect the non-target organisms (schröder, 1992). fish is the most susceptible to water contamination than any other aquatic organism. recently, biomarkers are widely used as early diagnostic tools for environmental quality assessment in polluted water bodies (cajaraville et al., 2000). measurement of haematological parameters are important in diagnosing the structural and functional status of animals exposed to the toxicant because blood parameters are highly sensitive to environmental or physiological changes and health conditions (talas et al., 2009; suvetha et al., 2010). similarly, monitoring of fish plasma electrolyte levels may allow partial assessment of the eco-physiological status of fish and to detect possible aquatic stress (suvetha et al., 2010). measurement of specific ion concentrations (na+, k+ and cl-) has potential as sensitive biomarkers of environmental chemical exposure. biochemical biomarkers are commonly used for detecting or diagnosing physiological changes in fish exposed to various toxic substances. among the biochemical biomarkers, plasma glucose and protein levels have long been used as indicators of stress in fish (ramesh, 2001). enzyme activities have also been used as sensitive indicators of stress in fish exposed to diverse groups of water pollutants and also to predict the possible levels of threat to life. measurement of plasma got and gpt enzyme activity in toxicant exposed fish serve as a valuable indicator of physiological changes or stress condition of fish (knox and greengard, 1965; remyla et al., 2008). many authors have reported the impact of neem based products on the physiology of aquatic organisms particularly fish. neem leaf extract alters the haematological and biochemical parameters in prochilodus lineatus at acute and sublethal concentrations (winkaler et al., 2007). extract of the neem bark had been reported to cause respiratory problems in tilapia zilli (omoregie and okpanachi, 1997) and crude extract of neem delayed the growth of cichlid fish (omoregie and okpanachi, 1992). in india, the usage of neem products has been increased rapidly such as soil fertilizer, insect repellent and an insecticide, molluscicidal, sterilant, antifeedant, antiattractant or repellent and ecdysone inhibitor (van der nat, 1991; sharma and dhiman, 1993; warbric et al., 1993; biswas et al., 2002), based on their frequent availability, biodegradability and safety for human and the environment (tiwari and singh, 2004). however, the impact of neem based products with reference to an indian major carp c. mrigala is very limited. cirrhinus mrigala is an important indian major carp and widely cultivated in different parts of india for edible and economic importance. therefore, in this study we aimed to evaluate the toxic effects of aqueous leaf extract of a. indica on certain haematological, ionoregulatory and biochemical parameters of c. mrigala. the present study is also aimed at establishing the safe limits of aqueous extracts of neem on water quality. saravanan et al. /journal of tropical forestry and environment vol. 01, no. 01 (2011) 14-26 16 2. materials and methods 2.1. experimental animal and water fingerlings of c. mrigala in the weight range of 8.0 ± 0.5 g and body length of 8.0 ± 1 cm were obtained from tamil nadu fisheries development corporation limited, aliyar fish farm, aliyar, tamil nadu, india. they were safely brought to the laboratory and stocked in a large cement tank (1,000 litre capacity). the tank was disinfected with potassium permanganate and washed thoroughly prior to introduction of fish. during the acclimatization period (20 days) fish were fed ad libitum with rice bran and groundnut oil cake in the form of dough once daily. one-third of water in the tank was renewed daily and feeding was withheld 24 h before the commencement of the experiment. in this study, tap water free from chlorine was used and the water had the following physico-chemical characteristics given in table 1(apha, 1998). before the start of experiment, fish were randomly divided into two groups which were housed in 200 l glass aquaria with tap water which was continuously aerated. table 1. physico-chemical features of water used for the experiment. physico-chemical parameters values temperature 27.4 + 1.2°c ph 7.2 + 0.09 dissolved oxygen 6.4 + 0.04 g l-l total alkalinity 18.6 + 8.0 g l-l total hardness 18.4 + 0.5 g l-l salinity 0.4 + 0.02 ‰ calcium 4.3 + 0.3 g l-l magnesium 2.6 + 0.6 g l-l values are mean ± s.e. of five individual observations 2.2. preparation of aqueous neem leaf extracts the leaves of neem (a. indica) were collected in and around bharathiar university campus, dried and chopped finely. the leaves were soaked in the ratio of 25 g of dried leaves per liter of water for 24 hours at room temperature (cruz et al., 2004). then the mixture was filtered and the extract (25 g l-l of stock solution) was used immediately for the experiment at different dilutions. 2.3. determination of 24 h lc 50 value of neem leaf extracts a static acute toxicity (24 h) test was conducted to determine the lc 50 value of neem leaf extract toxicity under laboratory condition. different concentrations of the neem leaf extract at 0.25, 0.50, 0.75, 1.0, 1.25, 1.50 ppm were prepared from the stock solution. for each concentration 10 fish randomly selected from the stock were introduced and kept in separate glass tanks (120 cm x 80 cm x 40 cm). journal of tropical forestry and environment vol. 01, no. 01 (2011) 14-26 17 three replicates were maintained for each concentration. a concurrent control was also maintained in three different tanks throughout the experimental period under identical conditions. the mortality/survival of fish was recorded after 24 h. the dead fish were removed from the tanks immediately. feeding was withheld during the bioassay experiment. the concentration at which 50% mortality of fish occurred after 24 h was taken as the medium lethal concentration (lc 50 ) for 24 h, which was 1.035 ppm. the lc 50 concentration for 24 h was calculated by the probit analysis method (finney, 1978). homogenicity of the population used in the present investigation was tested using chi-square test. 2.4. acute toxicity studies at the end of 24 h period, fish from the control and experimental aquaria were taken for the analysis of haematological indices (haemoglobin, haematocrit, erythrocyte, leucocyte, mean cellular volume, mean cellular haemoglobin and mean cellular haemoglobin concentrations), plasma electrolytes (na+, k+ and cl”), biochemical parameters (plasma glucose and protein) and enzymological parameters (got and gpt in gill, liver and muscle). 2.5. blood collection and haematological studies blood was drawn from cardiac region by cardiac puncture using plastic disposable syringe fitted with 26-gauge needle which was already moistened with heparin and expelled into separate heparinised plastic vials immediately on ice. blood samples were collected for haematological studies. haematocrit was estimated by microhaematocrit (capillary) method by nelson and morris (1989) using a microhaematocrit reader. erythrocytes and leucocytes were counted by the method of rusia and sood (1992) using haemocytometer and haemoglobin content of the blood was estimated by cyanmethaemoglobin method (drabkin, 1946). erythrocyte indices of fish viz., mean cell volume (mcv), mean cell haemoglobin (mch) and mean cell haemoglobin concentration (mchc) were calculated from rbc, ht, and hb according to lee et al. (1998) as follows: mcv [µm3 cell-1] = ht [v/v ratio] x1000/rbc [106 cell µl-1], mch [pg cell-1] = hb [gdl-1] x10/rbc [106 cell µl-1], and mchc [gdl-1] = hb [gdl-1]/ht [v/v ratio]. 2.6. estimation of plasma electrolytes plasma (blood) was prepared by centrifuging the blood sample at 10,000 rpm for 15 minutes. the sample was then used to measure plasma ionic (na+, k+ and cl-) levels. sodium and potassium were estimated by the method of maruna (1958), while chloride was estimated by modified method of tietz (1990) and young et al. (1975). 2.7. biochemical parameters plasma glucose was estimated by o-toluidine method (cooper and mcdanial, 1970) and plasma protein by the method of lowry et al. (1951). saravanan et al. /journal of tropical forestry and environment vol. 01, no. 01 (2011) 14-26 18 2.8. enzymological parameters the gills, liver and muscles were isolated from the control and treated fish and 100 mg of each tissue were weighed and homogenized with 2.5 ml of 0.25 m sucrose solution in ice cold condition (hogeboom et al., 1948). the homogenates were centrifuged for 20 minutes at 6000 rpm and clear supernatant fluid was taken for the estimation of got and gpt activities. got and gpt activities were estimated by 2, 4-dnph method (reitmen and franckel, 1957). 2.9. statistical analysis the data were statistically analysed at p<0.05. student’s t-test was used to test their significance. 3. results lc 50 (24h) value of a. indica leaf extract to c. mrigala was found to be 1.035 g l-l. during acute treatment, the fingerlings of c. mrigala exhibited behavioural responses such as profuse secretion of mucus, hypersensitivity, erratic swimming, loss of reflex, air gulping etc. the chi-square test on the toxicity data indicated that the fish population used for the experiments was homogeneous. 3.1. haematological indices the values of various haematological parameters such as hb, hct, rbc, wbc, mcv, mch and mchc of c. mrigala exposed to a. indica aqueous leaf extract toxicity for 24 h registered a significant (p<0.05) decrease from that of their control group (table 2). 3.2. plasma ionic levels plasma na+ level was significantly (p<0.05) lower (-33.05%) in the leaf extract treated fish than that of the control group at the end of 24 h (table 3). similarly, plasma cllevel was also decreased significantly table. 2: changes in hb, hct, rbc, wbc, mcv, mch and mchc level of a freshwater fish cirrhinus mrigala treated with acute concentration of neem leaf extracts (1.035 g l-1; 24 h). parameters control experiment percent change hb (g/dl) 4.3916 ± 0.024 1.4181± 0.081* -67.70 hct (%) 13.1 ± 0.044 4.97 ± 0.287* -62.29 rbc (million/cu.mm) 0.5660 ± 0.010 0.4640 ± 0.012* -18.02 wbc (1000/cu.mm) 13.94 ± 0.282 21.93 ± 0.551* +57.31 mcv (cubic micra) 235.15 ± 4.926 106.32 ± 4.967* -54.78 mch (picograms) 77.69 ± 1.456 30.50 ± 1.314* -60.74 mchc (g/ dl) 33.52 ± 0.109 28.71 ± 0.444* -14.34 values are mean ± s.e. of five individual observation, (+) denotes percent increase over control, (-) denotes percent decrease over control, * values are significant at p < 0.05, (based on t test). journal of tropical forestry and environment vol. 01, no. 01 (2011) 14-26 19 (p<0.05) in the treated fish when compared to control group (table 3). however, plasma k+ level was significantly (p<0.05) higher in treated fish (table 3). 3.3. biochemical parameters in biochemical parameters, plasma glucose was increased in treated fish (+60.06%) when compared to control group (table 4). on the contrary, plasma protein level decreased upto -19.40% (table 4). 3.4. enzymological parameters saravanan et al. /journal of tropical forestry and environment vol. 01, no. 01 (2011) 14-26 table. 3: alterations in plasma sodium, potassium and chloride levels of control and neem leaf extracts treated fish (1.035 g l-1; 24 h). values are means ± s.e. of five individual observations; significant (p < 0.05). parameters control experiment percent change sodium (mmol/l) 151.80 ± 1.104 101.62 ± 2.032* -33.05 potassium (mmol/l) 7.6545 ± 0.210 11.6199 ± 0.030* +51.80 chloride (meq/l) 119.142 ± 3.008 48.127 ± 4.668* -59.60 values are mean ± s.e. of five individual observation, (+) denotes percent increase over control, (-) denotes percent decrease over control, * values are significant at p< 0.05, (based on t test). table. 4: changes in plasma glucose and protein content of control and neem leaf extracts treated fish (1.035 g l-1; 24 h). values are means ± s.e. of five individual observations; significant (p < 0.05). parameters control experiment percent change plasma glucose 89.72 ± 3.215 143.61 ± 1.967* +60.06 (mg/100ml) plasma protein (µg/ml) 3.1751 ± 0.124 2.5590 ± 0.085* -19.40 values are mean ± s.e. of five individual observation, (+) denotes percent increase over control, (-) denotes percent decrease over control, * values are significant at p < 0.05, (based on t test). tables. 5: alterations of got activity in the gill, liver and muscle of a freshwater fish cirrhinus mrigala treated with acute concentration of neem leaf extracts (1.035 g l-1; 24 h). values are means ± s.e. of five individual observations; significant (p < 0.05). got activity (iu/l) control experiment percent change gill 44.6 ± 0.7483 107.4 ± 8.134* +140.80 liver 56.0 ± 1.5166 65.6 ± 1.662* +17.14 muscle 54.0 ± 0.7071 97.0 ± 2.236* +79.62 values are mean ± s.e. of five individual observation, (+) denotes percent increase over control, * values are significant at p< 0.05, (based on t test). 20 in this study, got and gpt activities were significantly (p<0.05) higher in gill, liver and muscle of fish exposed to aqueous leaf extract of a. indica than that of the control group (tables 5-6). 4. discussion the various types of stressors in aquatic ecosystems and aquaculture practices have been shown to induce some changes in the physiological variables of fish (martinez and souza, 2002). in this study, we found that the median lethal concentration (lc 50 for 24h) of aqueous extract of neem leaf to the fingerlings of c. mrigala was 1.035 g l-1 which indicates that aqueous extract of neem leaf is toxic to fish. the toxicity of neem extract varies depending on the fish species. the 24 h lc 50 of neem leaves extract for p. lineatus was 4.8 g l-1 (cruz et al., 2004), 96 h lc 50 of neem leaf extract for 96 h in channa punctatus was 3.00 ppm (farah et al., 2006), and 24 and 96 h lc 50 of nerium indicum leaf extracts for channa punctatus was 17.34 mg l-1 and 13.58 mg l-1 respectively (tiwari and singh, 2003). according to singh and singh, (2002) the 24 h lc 50 values of stem bark extracts of euphorbia royleana, jatropha gossypifolia, n. indicum and thevetia peruviana to c. punctatus was 0.050 g l-1, 4.61 g l-1, 0.097 g l-1, and 4.05 g l-1, respectively. behavioural toxicology is a tool for hazard assessment of water pollution. in the present investigation, during acute treatment, behavioural responses such as erratic movements, increasing mucous secretion, body imbalance, surface floating, restlessness and loss of equilibrium were observed. similar observations were also observed by tiwari and singh (2004) in fish c. punctatus exposed to stem bark extract of neem and in lepidocephalichthys guntea exposed to nimbecidine and neem gold (mondal et al., 2007). alterations in physiological and biochemical parameters of toxicant treated fish have recently emerged as vital indices for water quality assessment in the field of environmental toxicology (suvetha et al., 2010). moreover, haematological parameters are closely associated to the response of the fish to the environment (tiwari and sing, 2006). changes in the erythrocyte profile of toxicant treated fish indicate a compensation of oxygen deficit in the body due to gill damage (drastichova et al., 2004). reduction in rbc may be caused either by the inhibition of erythropoiesis or by the destruction of red cells (hota, 1995) and destruction of hematopoietic tables. 6: alterations of gpt activity in the gill, liver and muscle of a freshwater fish cirrhinus mrigala treated with acute concentration of neem leaf extracts (1.035 g l-1; 24 h). values are means ± s.e. of five individual observations; significant (p < 0.05). gpt activity (iu/l) control experiment percent change gill 45.8 ± 1.2806 73.0 ± 4.427* +59.30 liver 51.8 ± 2.6533 66.2 ± 4.030* +27.79 muscle 57.6 ± 0.9273 96.0 ± 5.805* +66.66 values are mean ± s.e. of five individual observation, (+) denotes percent increase over control, * values are significant at p < 0.05, (based on t tes journal of tropical forestry and environment vol. 01, no. 01 (2011) 14-26 21 tissue in kidney and spleen (iwama et al., 1976). svobodova et al. (1991) reported that reduced haemoglobin content and haematocrit in toxicant exposed fish may be due to disruption of haemopoietic processes and accelerated disintegration of erythrocyte cell membranes. in ictalurus punctatus the decreased hb content was due to the swelling of rbc, as well as to poor mobilization of hb from the spleen and other haemopoietic organs (scott and rogers, 1981). in this study, the significant decrease in rbc count, haemoglobin content and haematocrit values of fish c. mrigala treated with aqueous extract of neem leaf h might have resulted from destruction of rbcs due to erythroblastosis leading to anemia. zhang et al. (2007) investigated a significant decrease in haematological indices including mch, mchc and mcv in carassius auratus to intraperitoneal injection of extracted microcystins and suggested that the decrease in haematological indices may be a compensation for impaired oxygen uptake due to gill damage. similar alterations of mch, mcv and mchc values of c. mrigala were noted in this study which may be due to swelling of red blood cells or release of young erythrocytes containing less hemoglobin into the blood circulation (sobecka, 2001). wbcs are involved in the regulation of immunological function and their numbers increase as a protective response in fish to stress (nussey et al., 2002; pimpao et al., 2007). winkaler et al. (2007) reported that wbc levels in neem leaf extract treated fish increased from the control level, as a consequence of gill damage. increased total leucocyte cell count in monosex nile tilapia, oreochromis niloticus exposed to acute concentration of deltamethrin may be due to stimulated lymphopoiesis and enhanced release of lymphocytes from lymphomyeloid tissue (el-sayed et al., 2007). in the present study, the significant increase in the number of wbc indicates the stress condition of the fish caused by neem leaf extract which might have produced hypoxia and gill damage. freshwater animals compensate their renal and surface loss of ions, mainly sodium and chloride by absorbing these ions from the external medium and maintain their normal physiological process and body fluid homeostasis with the help of ion/osmoregulatory processes (hwang and lee, 2007; suvetha et al., 2010). the effects of toxicants on osmotic and ionic regulation have been calculated by means of measuring concentrations of individual ions and total osmolarity in fish plasma (barcarolli and martinez, 2004). mathan et al. (2010) reported that alterations in ionic balance may be due to due to stress effects on the ionoregulatory organs. mccarty and houstan (1976) reported that the decrease in plasma electrolyte levels tend to be associated with increases in tissue concentration, particularly sodium and chloride. wood et al. (1996) proposed that the net loss of na+ and clat the gills cause a steady decline in plasma concentration of these ions. further, an apparent decrease of blood chloride concentrations in fish might be due to reduced activity of carbonic anhydrase or interference of cortisol (thomas and murthy, 1976). decreased level of plasma potassium indicates the inhibition of the na+/k+ atpase activity (suvetha et al., 2010). further, osmoregulatory failure may also be a reason for decreased levels of major plasma electrolytes. in the present investigation, the decreased level of plasma electrolytes levels might have resulted from the toxicity of neem leaf extract which may have accumulated on the gill surface; either had damaged or altered the membrane permeability leading to lesser intake of electrolytes into the body or efflux of the same to the exterior. freshwater animals compensate their renal and surface loss of ions, mainly sodium and chloride, by absorbing these ions from the external medium through specialized saravanan et al. /journal of tropical forestry and environment vol. 01, no. 01 (2011) 14-26 22 surface structures (gills in fish). gills of freshwater fish contain the machinery for the active transport of electrolytes and play an important role in the transport of respiratory gases and regulating of osmotic and ionic balance. toxic substances may cause damage to gill tissues, thereby reducing the oxygen consumption and disturbing the osmoregulatory function of aquatic organisms. on the other hand, a significant increase in plasma potassium level might be due to this fact that this ion was transported from other tissues to blood or their consequent reduction in the tissues due to imbalances in the osmoregulation process. biochemical parameters can be helpful to identify the target organs of toxic effects and also the general health condition of animals. they also provide early warning of potentially harmful changes in stressed organisms (ferreira et al., 2007). the increase in blood glucose level might be resulted from an increase in plasma catecholamine and corticosteroid hormones (pickering, 1981). in the present study also hyperglycemic condition was observed which may be due to coping up the stress caused by aqueous neem leaf extract. martinez et al. (2004) reported that fish under stress conditions may mobilize protein to meet energy requirements and to sustain increased physiological activity. the decrease in protein level observed in the freshwater fish c. punctatus exposed to latices of e. royleana and j. gossypifolia may be attributed to the destruction or necrosis of cells and consequent impairment in protein synthesis (singh and singh, 2002). a similar mechanism may be operated in the present study also. manavalaramanujam and ramesh (1996) reported that the elevation of got and gpt activity in pesticide treated fish indicates the increased energy demands under pesticide stress. increased got and gpt indicates hepatic tissue damage (agrahari et al., 2007). in the present study, the activity of both gpt and got was increased in the gill, liver and muscle tissue of c. mrigala indicating damage of the organs due to accumulation of aqueous extract of neem leaf or increased metabolism as the organism tries to mitigate the induced stress. moreover, detoxification process may not be sufficiently effective to prevent the action of neem leaf extract on the system resulting an increase in got and gpt activities in gill, liver and muscle of fish. 5. conclusion in india, the health hazard of a. indica plant leaf extract to aquatic organisms particularly in c. mrigala has not been studied in detail. the findings of the present study showed that neem leaf extracts (1.035 g l-l) affects the hematological, ionoregulatory, biochemical and enzymological parameters of c. mrigala even during a short-term exposure (24h). these parameters could be effectively used as potential biomarkers of neem leaf extracts toxicity to the freshwater fish in the field of environmental biomonitoring. the observed lc 50 value and altered parameters may help to establish the safer level of the aqueous extracts of a. indica to the aquatic environment and aquaculture farms. furthermore, chronic studies on these parameters need to be further investigated in future. references agrahari, s., kashev, c., pandey, gopal, k., 2007. biochemical alteration induced by monocrotophos in the blood plasma of fish, channa punctatus (bloch). pestic. biochem. physiol. 268-272. journal of tropical forestry and environment vol. 01, no. 01 (2011) 14-26 23 apha., 1998. standard methods for the examination of water and wastewater, twentieth ed. american public health association, washington, dc. barcarolli, if., martinez, c.b.r., 2004. effects of aluminium in acidic water on hematological and physiological parameters of the neotropical fish leporinus macrocephalus (anostomidae). bull. environ. contam. toxicol. 72, 639-646. biswas, k., chattopadhyay, i., banerjee, r.k., bandyopadhyay, u., 2002. biological activities and medicinal properties of neem (azadirachta indica). cur. sci. 82, 1336-1345. cajaraville, mp., bebianno, m.j., blasco, j., porte, c., sarasquete, c., viarengo, a., 2000. the use of biomarkers to assess the impact of pollution in coastal environments of the iberian peninsula: a practical approach. sci. total. environ. 247, 295-311. chattopadhyay, r.n., maitra, s.k., chattopadhyay, r.r., 1993. possible mechanism of antihyperglycemic effect of azadirachta indica leaf extract: part i. fitoterapia. 64, 332-335. cooper, g.r., mcdaniel, v., 1970. the determination of glucose by the o-toluidine method. standard method for clinical chemistry, 159. cruz, c., machado-neto, j.g., menezes, m.l., 2004. toxicidade aguda do inseticida paration metílico e do biopesticida azadiractina de folhas de neem (azadirachta indica) para alevino e juvenil de pacu (piaractus mesopotamicus). pesticidas: revista de ecotoxicologia e meio ambiente. 14, 92-102. drastichova, j., svobodova, z., luskova, v., machova, j., 2004. effect of cadmium on hematological indices off common carp cyprinus carpio (l.). bull. environ. contam. toxicol. 72, 725-732. el-sayed, y.s., saad, t.t., el-bahr, s.m., 2007. acute intoxication of deltamethrin in monosex nile tilapia, oreochromis niloticus with special reference to the clinical, biochemical and haematological effects. environ. toxicol. pharmacol. 24, 212-217. farah, a.m., bushra, a., ahmad, w., 2006. antimutagenic effect of neem leaves extract in freshwater fish, channa punctatus evaluated by cytogenetic tests. sci. total environ. 364, 200-214. ferreira, j.g., hawkins, a.j.s., bricker, s.b., 2007. management of productivity, environmental effects and profitability of shellfish aquaculture-the farm aquaculture resource management (farm) model. aquaculure. 264, 160-174. finney, d.j., 1978. in: statistical methods in biological assay, third ed. griffin press., london, u.k, 508. hogeboom, g.h., schneider, w.c., pallade, g.e., 1948. cytochemical studies of mammalian tissues i. isolation of intact mitochondria from rat liver; some biochemical properties of mitochondria and submicroscopic particulate material. j. biol. chem. 72, 619-635. hota, s., 1995. toxic effect of arsenic on haemato biochemical abnormalities in channa punctatus (bloch). j. ecotoxicol. environ. monit. 5, 249 255. hwang, p.p., lee, t.h., 2007. new insights into fish ion regulation and mitochondrion-rich cells. comp. biochem. physiol. 48, 479-497. iwama, g.k., greer, g.l., larkin, p.a., 1976. changes in some hematological characteristics of coho salmon (oncorhynchus kisutch) in response to acute exposure of dehydroabietic acid (dhaa) at different exercise levels. j. fish res. board canada. 33, 285-289. knox, w.e., greengard, o., 1965. in: an introduction to enzyme physiology, weber, g. (edn.), advances in enzyme regulation. pergamon press., new york, 247-248. saravanan et al. /journal of tropical forestry and environment vol. 01, no. 01 (2011) 14-26 24 kreutzweiser, d.p., back, r.c., sutton, t.m., pangle, k.l., thompson, d.g., 2004. aquatic mesocosm assessments of a neem (azadirachtin) insecticide at environmentally realistic concentrations-2: zooplankton community responses and recovery. ecotoxicol. environ. safe. 59, 194-204. lee, r.g., foerster, j., jukens, j., paraskevas, f., greer, j.p., rodgers, g.m., 1998. wintrobe’s-clinical hematology, tenth en. lippincott williams and wilkins., new york, usa. lowry, o.h., rosenbrough, n.j., farr, a.l., randell, r.j., 1951. protein measurement with foline phenol reagent. j. biol. chem. 193, 265-275. manvalaramanujam, r., ramesh, m., 1996. sublethal toxicity of phosalone on transaminases of a freshwater fish labeo rohita. j. ecol. environ. conserv. 2, 179-181. martinez, s.o., 2002. nim-azadirachta indica: natureza, usos múltiplose produção. instituto agronômico do paraná (iapar), londrina, pr. martinez, c.b.r., nagae, m.y., zaia, c.t.b.v., zaia, d.a.m., 2004. morphological and physiological acute effects of lead in the neotropical fish prochilodus lineatus. brazilian j. biol. 64, 797-807. martinez, c.b.r., souza, m.m., 2002. acute effects of nitrite on ion regulation in two neotropical fish species. comp. biochem. physiol. a. 33, 151-160. maruna, r.f.l., 1958. quantitative estimation of sodium (na+), potassium (k+) in human serum by colorimetric method. clin. chim. acta. 2, 581-585. mathan, r., senthil kumar, k., mahalashmi priya., 2010. alterations in plasma electrolyte levels of a freshwater fish. cyprinus carpio exposed to acidic ph. toxicol. environ. chem. 92, 149-157. mccarty, l.s., houston, a.h., 1976. effects of exposure to sublethal levels of cadmium upon waterelectrolyte status in the gold fish, carassius auratus. j. fish biol. 9, 11-19. mondal, d., barat, s., mukhopadhyay, m.k., 2007. toxicity of neem pesticides on a fresh water loach, lepidocephalichthys guntea (hamilton buchanan) of darjeeling district in west bengal. j. environ. biol. 28, 119-22. nelson, d.a., morris, m.w., 1989. basic methodology. chap. 27. hematology and coagulation, part iv, in: clinical diagnosis and management by laboratory methods. nelson, d.a., henry, j.b. seventieth ed. henry, j.b, w.b. saunder company., philadelphia, u.s.a. 578-625. nussey, g., van, vuren, j.h.j., du preez, h.h., 2002. the effect of copper and zinc at neutral and acidic ph on the general hematology and osmoregulation of oreochromis mossambicus. african j. aquat. sci. 27, 61-84. omoregie, e., okpanachi, m.a., 1992. growth of tilapia zilli exposed to sublethal concentrations of crude extracts of azadirachta indica. acta hydrobiol. 34, 281-286. omoregie, e., okpanachi, m.a., 1997. acute toxicity of water extracts of bark of the neem plant, azadirachta indica (lodd) to the cichlid tilapia zillii (gervais). acta hydrobiol. 39, 47-51. pickering, a.d., 1981. stress and compensation in teleostean fishes. response to social and physical factors, in: pickering, a.d. (edn.), stress and fish, academic press., new york/london, 295-322. pimpao, c.t., zampronio, a.r., silva de assis, h.c., 2007. effects of deltamethrin on hematological parameters and enzymatic activity in ancistrus multispinis (pisces, teleostei). pestic. biochem. physiol. 88:122-127. ramesh, m., 2001. toxicity of copper sulphate on some haematological parameters of a freshwater teleost cyprinus carpio var. communis. j. indian fish. assoc. 28, 131-136. journal of tropical forestry and environment vol. 01, no. 01 (2011) 14-26 25 reitman, s., frankel, s., 1957. a colorimetric method for the determination of glutamic-oxaloacetic and glutamic-pyruvic transminases. american j. clin. pathol. 33:1-13. remyla, s.r., ramesh, m., sajwan, k.s., senthil kumar, k., 2008. influence of zinc on cadmium induced haematological and biochemical responses in a freshwater teleost fish catla catla. fish. physiol. biochem. 34, 169-174 rusia, v., sood, s.k., 1992. routine haematological tests, in: medical laboratory technology, kanai, l. mukerjee, (edn.), i. fifth reprint, tata mcgraw hill publishing company limited., new delhi, 252-258. schroder, p., 1992. neem azal/neem azal f in the aquatic environment. in: kleeberg, h. (ed.), practice oriented results on use and production of neem ingredients. proceedings of 1st workshop, druck and graphic giessen., germany, 109-121. scott, a.l., rogers, w.a. 1981. hematological effects of prolonged sublethal hypoxia on channel catfish ictalurus punctatus (rafinesque). j. fish. biol. 18, 591-601. sharma, v.p., dhiman, r.c., 1993. neem oil as sand fly (diptera: psychodidae) repellant. j. american mosq. control assoc. 9, 364-366. singh, d., singh, a., 2002. biochemical alteration in freshwater fish channa punctatus due to latices of euphorbia royleana and jatropha gossypifolia. environ. toxicol. pharmacol. 12, 129-1. sobecka, e., 2001. changes in the iron leveling the organs and tissues of wells catfish, silurus glanis l. caused by nickel. acta ichthyl. et pisc. 31, 127-143. suvetha, l., ramesh, m., saravanan, m., 2010. influence of cypermethrin toxicity on ionic regulation and gill na+/k+-atpase activity of a freshwater teleost fish cyprinus carpio. environ. toxicol. pharmacol. 29, 44-49 svobodova, d., ravds, j., palackova, l., 1991. unified method of haematological examination of fish. research institute of fish culture and hydrobiology, vodamy, czechoslovakia. talas, z.s., gulhan, m.f., 2009. effects of various propolis concentrationson biochemical and hematological parameters of rainbow trout (oncorhynchusmykiss). ecotoxicol. environ. safe. 72, 1994-1998. thomas, p.c., murthy, t.c., 1976. studies on the impact of a ferric organic pesticide on certain fish enzymes. indian j. animal sci. 46, 619-624. tietz, n.w., 1990. in: clinical guide to laboratory test, second edn. w.b. saunders co., philadelphia, 118. tiwari, s., singh, a., 2003. control of common freshwater predatory fish, channa punctatus, through nerium indicum leaf extracts. chemosphere. 53, 865-875. tiwari, s., singh, a., 2004. piscicidal and anti-acetyl cholinesterase activity of euphorbia royleana stem bark extracts against freshwater common predatory fish channa punctatus. environ. toxicol. pharmocol. 18, 47-53. tiwari, s., singh, a., 2006. biochemical stress response in freshwater fish channa punctatus induced by aqueous extracts of euphorbia tirucalli plant. chemosphere. 64, 36-42. van der nat, m.g., van der sluis, k.t.d., labadie, r.p., 1991. ethnophormocognostical survey of a. indica juss (maliaceae). j. ethnopharmacol. 35, 1-24. saravanan et al. /journal of tropical forestry and environment vol. 01, no. 01 (2011) 14-26 26 warbric, e.v., barker, g.c., rees, h.h., howells, r.e., 1993. the effect of invertebrate hormones and potential hormone inhibitors on the third larval moult of the filarial nematode, dicrofilaria immitis in vitro. parasitol. 107, 459-463. winkaler, e.u., santos, t.r.m., machado-neto, j.g., martinez, c.b.r., 2007. acute lethal and sublethal effects of neem leaf extract on the neotropical freshwater fish prochilodus lineatus. comp. biochem. physiol. c. 145, 236-244. wood, c.m., hogstrand, c., glavez, f., munger, r.s., 1996. the physiology of waterborne silver toxicity in freshwater rainbow trout, oncorhynchus mykiss. the effects of silver thiosulfate. aquat. toxicol. 35, 111-125. young, d.s., pestaner, l.c., gibberman, v., 1975. effects of drugs on clinical laboratory tests. clin. chem. 21, 1d-432d. zhang, x., xie, p., li, d., shi, z., 2007. hematological and plasma biochemical responses of crucian carp (carassius auratus) to intraperitoneal injection of extracted microcystins with the possible mechanisms of anemia. toxicology. 49, 1150-1157. journal of tropical forestry and environment vol. 01, no. 01 (2011) 14-26 microsoft word bandara and vlosky bandara & vlosky /journal of tropical forestry and environment vol. 2, no. 02 (2012) 49-62 49 an analysis of the u.s. wood products import sector: prospects for tropical wood products exporters w.a.r.t.w. bandara* 1 and r.p. vlosky 2 1 environmental management & conservation program, department of zoology, university of kelaniya, sri lanka 2 forest products development center, school of renewable natural resources, louisiana state university agricultural center, baton rouge, la, 70803, usa date received: 06-15-2012 date accepted: 16-08-2012 abstract the u.s. has dramatically altered its wood product imports and exports during the past few years, and at present, it is the second largest wood product importer in the world. hence, an understanding of market structures, factors in selecting foreign suppliers, and the emphasis placed on environmental issues/certification are critical to understand from the perspective of wood products importers in the u.s. this study provides an analysis of the u.s. wood products import sector with special emphasis on current and future opportunities for tropical wood products exporters to the u.s. market. in this study, 158 wood products importers in the u.s. were surveyed using a mailing questionnaire. the adjusted response rate was 40.6 percent. results indicated that most of the respondents were small to medium scale firms, but major importers of wood products. according to respondents, wood products to the u.s. mainly come from brazil, chile, and china. from the importers’ perspective, brazilian wood products ranked first for its quality followed by wood products from chile and finland. product quality, long term customer relationships, on-time delivery of orders, fair prices, and supplier reputation were the factors deemed important in selecting overseas suppliers. majority of respondents were importing certified wood products. fsc, sfi, and iso 14000 were the mostly accepted certification programs. however, certification was not a major factor in foreign supplier selection criteria. when considered the u.s. wood products importers’ tendency to diversify their products and species imported, attractive opportunities exist for wood products suppliers from tropical countries. keywords: wood products, imports, exports, certified wood, tropical wood suppliers 1. introduction growing demand for wood has exerted a greater pressure on primary old growth forests in the world. therefore, many countries are resorting to secondary timber resources such as forest plantations to meet the rising demand. other than the secondary timber resources, imports also play a key role in meeting the demand for timber and wood products in most countries (u.s. department of commerce, 2008). the rapid increase of domestic wood demand has driven some nations to a state where the domestic wood production is no longer able to meet the demand while forcing some countries to shift from being net exporters of wood products to net importers (fao, 2006). hence, the need for crossboundary trade of wood products has intensified. *correspondence: rangika@kln.ac.lk tel: +94 11 2804515 issn 2235-9370 print / issn 2235-9362 online ©2012 university of sri jayewardenepura bandara & vlosky /journal of tropical forestry and environment vol. 2, no. 02 (2012) 49-62 50 although policy formulators tend to encourage exports, ideas on imports are diverse and conflicting. however, imports are also vital to a country’s economy in many ways. imports can fulfill the accessible deficit of goods and services which are essential for the well being of people while often facilitating the sustainable utilization of existing resources. in addition, imports generate employment in handling, transportation, marketing, and other segments of the value chain. wood products industry and trade accounts for approximately 1% of the world’s gdp. despite recent negative developments in the global economy, an estimated 3.4 billion cubic meters of wood was produced in 2010, and the international trade or imports in wood products was estimated at us$ 227 billion (armstrong, 2011). 1.1. the u.s. wood products imports market the u.s. is a major player in the global wood products market. despite china’s recent emergence as the leading importer of primary wood products such as softwood logs, lumber, and pulp, the u.s. still remains as the second largest wood product importer in the world (flynn, 2012). the u.s. housing constructions sector is the principal driver of wood and wood products markets from the demand perspective (united nations, 2011). after single family housing constructions, repair and remodel applications of wood sold predominantly through home-center retailers account for the second largest demand market for wood products in the u.s. (perera et al., 2008). housing starts, resale and repair/remodel markets are directly related to u.s. furniture and imports as well (pirc and vlosky, 2010). residential and non-residential constructions, repair and remodeling, furniture and other manufactured products, and packaging and shipping end-use markets collectively account for about 80% to 90% of all solid wood products consumption in the u.s. (howard and mckeever, 2012). the recent collapse in u.s. housing market has heavily impacted the u.s. wood products import sector. for instance, the u.s. single-family housing starts in may 2009 dropped by 41% compared to may 2008 (buehlman and schuler, 2009). however, recent reports hint slow revival of the u.s. housing market and allied wood products markets (united nations, 2011; wood markets, 2011). the wood products imports rose by 16% in 2010 compared to 2009, and this upturn was attributed to the 6% increase in housing starts (wood markets, 2011). however, the u.s. wood imports value in 2010 (reaching us$ 20 billion) was well below the value of the peak in 2005 where total wood imports exceeded us$ 43 billion (armstrong, 2011). softwood lumber (up by us$ 679 million), builders’ carpentry (up by us$ 81 million), hardwood plywood (up by us$ 251 million), mouldings (up by us$ 115 million), and osb (up by us$ 178 million) were the top five imported wood products in 2010 that showed noticeable growth in terms of value, compared to 2009 (wood markets, 2011). according to food and agriculture organization (2011), u.s. was the leading importer of wood-based panels in the world for the year 2010, and was the second largest importer of sawn-wood, wood pulp, and paper products. 1.2. tropical hardwood imports to the u.s. despite being a leading importer of wood and wood-based products in the global market, the u.s. has traditionally been a relatively small consumer of tropical hardwoods. however, wood products imports of tropical origin have steadily increased over the years because of their unique properties and aesthetics, customer preference for tropical hardwood species has increased, and therefore, tropical hardwoods are successfully competing with domestic hardwood species in u.s. markets. for instance, the u.s. hardwood products imports in 2006 totaled us$ 3.6 billion (excluding furniture and builders’ joinery) and tropical wood products imports accounted for about 30% of this value (ekström and goetzl, 2007). the value of tropical wood products imports to the u.s. (excluding furniture) in 2006 was nearly us$ 1.6 billion. tropical timber imports typically find end-uses in distinct and important high-end, valueadded niche markets of furniture, cabinets, flooring, architectural woodwork, decking and mouldings (ekström and goetzl, 2007). for instance, tropical hardwood plywood accounted for an estimated 30% of bandara & vlosky /journal of tropical forestry and environment vol. 2, no. 02 (2012) 49-62 51 overall hardwood plywood imported in 2006, while tropical hardwood flooring accounted for 45% of wood flooring imports (fao, 2007). a greater share of tropical wood products to the u.s. comes from south american region. brazil is the largest supplier with peru, chile and bolivia being the other leading south american suppliers to the u.s. (ekström and goetzl, 2007). jatoba (hymenaea courbaril ), mahogany (swietenia spp.) and guariuba have long been the most popular tropical species from this region (itto, 2011). however, recent trade restrictions due to increased environmental concerns have curtailed the supply of certain species. malaysia, indonesia, vietnam, and myanmar are the major suppliers of tropical wood products from the south-east asian region. according to trade statistics, the us remained the largest market for malaysian furniture exports and vietnam wood products (huong and dao, 2007; globalwood, 2011). meranti (shorea spp.), keruing (dipterocarpus spp.) and kapur (dryobalanops spp.) are the major species supplied to u.s. markets form these countries (itto, 2011). west africa (mainly ghana and cameroon) is another major tropical hardwood supply region to the u.s. for instance, according to itto (2011), ghana’s tropical wood exports to u.s. were 4% of the total exports value in 2010, a 100% growth compared to 2009. african mahogany (khaya spp.), okoume (aucoumea klaineana) and sapele (entandrophragma cylindricum) are among the major tropical species imported to the u.s. (globalwood.org, 2011). imported hardwood plywood accounts for a significant share in the u.s. plywood market. china has recently emerged as the leading tropical hardwood plywood supplier to the u.s. while brazil, malaysia, and indonesia being the other leading suppliers (ekström and goetzl, 2007). however, the tropical wood products imports also suffered due to the recent recession in the u.s. economy, and at present showing signs of gradual regaining (united nations, 2011). 1.3. demand for environmentally certified wood products until recently, the u.s. wood products import markets have been less strict on environmental claims in comparison to european union import markets. however, with ever-increasing environmental awareness throughout the globe, the u.s. has also introduced new laws to regulate the trade of environmentally unsustainable wood. the lacey act, a law banning the trade of illegally sourced plants and their products including timber and wood products is one such example (eia-global.org, 2008). in addition, market based mechanisms such as forest certification also continues to generate promise, discussion, and debate in the u.s. wood products market (perera et al., 2008). recent studies on u.s. consumer perspectives and preference for certified wood suggest that overall consumer understanding and preference for environmentally certified wood has increased (ozanne and vlosky, 2003; anderson and hansen, 2004). however, for a typical individual, the importance of other product attributes tend to outweighed that of certification (anderson and hansen, 2004). from the supplier side, a study on non-industrial private forest (nipf) landowners in the u.s. south further showed that nipf landowner are quite knowledgeable about certification though they are not in favour of certifying private forest lands (perera et al., 2007). a comparative national study by vlosky et al. (2009) on the u.s. value-added wood products sector revealed that certification awareness and participation have increased significantly from 2002 to 2008. despite satisfactory awareness of consumers and wood products manufacturers/producers on forest certification, the demand for environmental certification in the u.s. seems to be driven by major retailers and environmental ngos (perera et al., 2007; 2008). for instance, a recent survey of top 500 home-center retailers in the u.s. found that improving the company’s image and having preexisting certified suppliers as the major reasons for purchasing/selling certified wood products. certification/eco-labeling was ranked last in wood products supplier selection criteria of u.s. home center retailers (perera et al., 2008). although above mentioned studies and trade reports provide a general understanding of the u.s. wood products market, recent studies conducted specifically on the u.s. wood products importers to bandara & vlosky /journal of tropical forestry and environment vol. 2, no. 02 (2012) 49-62 52 provide a broader picture of the u.s. wood product import sector are relatively less evident in literature (draffan, 2000; oskooee and chakrabarti, 2003). hence, this study specifically attempts to accomplish the objectives of: (1) identify the structure of the u.s. wood product import market based on the u.s. wood product importers’ perspective (2) explore demand factors and opportunities in the u.s. market for tropical exporters selling into the u.s. market and (3) understand u.s. importer perceptions towards forest certification. 2. materials and methods a structured questionnaire was the primary research instrument used in this study. questionnaire items were developed carefully to address the research objectives. respondent level of agreement or level of importance for items were measured using a 5-point likert type scale anchored by 1 = strongly disagree to 5 = strongly agree or 1 = not important at all to 5 = very important respectively. in addition, the questionnaire collected company demographics and the current business environment from importers’ perspective. it further included open ended questions that captured additional information as comments, suggestions or concerns for further analysis. the questionnaire was pretested with a subset of 20 representatives from the sample and revised before the final mailing. during the period fall 2007 to spring 2008, a mail questionnaire was sent to 158 wood products importers in the u.s. the sample frame was selected from the buyers and sellers directory of the forest products industry, u.s.a. (2007). accordingly, there were 158 wood products importers listed in the directory, and all the listed companies were included as the sample for this study. the sample contained companies that import softwood and hardwood lumber, plywood, osb, mdf, particleboard, fence and posts, mouldings, hardwood veneer, flooring, doors, and furniture parts. a mail questionnaire approach was chosen considering the resource availability and simplicity. in addition, this method allows high degree of anonymity and has the ability to cover a sample dispersed in a wide geographical range. mailing procedures followed the tailored design method (dillman, 2000) and included a pre-notification postcard, the first questionnaire mailing with a postage paid return envelope, a reminder postcard, and a second mailing to first mailing non-respondents. personalized cover letters that accompanied the questionnaires were signed by the principal investigator and were addressed to marketing managers or marketing vice presidents by name and title. data analysis the information collected using the questionnaire included nominal, interval, and ordinal scale data as well as descriptive text responses. data were entered into an excel® spread sheet and were cleaned by checking for completeness, validity, reliability and consistency. spss® version 15.0 (statistical package for social sciences) was employed in data analysis. both descriptive and inferential statistical techniques were used. nonresponse bias is often a common concern in survey research because it raises the question of whether those who did respond are different in some important way from those who did not respond (dillman, 2000). research has shown that late respondents typically respond similarly to non-respondents (perera et al., 2007; 2008). accordingly, second mailing respondents, as a proxy for non-respondents were compared to first mailing respondents. the t-test indicated no statistical difference in company size measured by gross sales (p = 0.11) or the magnitude of imports i.e. number of containers (p = 0.07) at 0.05 significance level. hence, both first mailing and second mailing respondents were treated as one sample in all statistical analysis. bandara & vlosky /journal of tropical forestry and environment vol. 2, no. 02 (2012) 49-62 53 3. results 3.1. general profile out of the 158 companies of u.s. wood products importers surveyed, 71 companies responded. seventeen companies responded to the survey did not import wood products in 2006. therefore, the number of usable responses was 54. furthermore, eight surveys were returned as undeliverable. accordingly, the adjusted response rate was 40.6 percent. majority of the respondents (52) were headquartered in the u.s. while two respondents were headquartered outside the u.s. i.e. south korea and finland. of those who were headquartered in the u.s., 94% were from the western and southern regions (figure 1). figure 1: distribution of respondent corporate locations, percent of respondents (n = 52) the questionnaire gathered information on respondents’ gross sales, percent of total gross sales from imports, and quantity imported in 2006. approximately 37% of respondents had gross sales below us $5 million. only 11% of respondents had gross sales of over us $ 100 million. a plurality (80%) had gross sales below us $50 million (figure 2). figure 2: total gross sales in 2006 percent respondents (n=54) bandara & vlosky /journal of tropical forestry and environment vol. 2, no. 02 (2012) 49-62 54 more than half of the respondents (55.8%) indicated that over 50% of their sales were from imported wood products. of the 54 respondents, 36.5% attributed 90% or more of their sales to imports. these may represent the major importers of wood products to the u.s. (figure 3). respondents were also asked about the number of wood product containers they imported in 2006 (figure 4). thirty-four percent of the respondents imported 1-50 containers while more than half of respondents (56%) were importing more than 100 containers of wood products. in terms of number of employees, 7.4% of the respondents had more than 500 employees. another 7.4% respondents employed a staff between 101 to 500 workers. nearly 72% of respondents had 25 or less employees. figure 3: percent of total gross sales from imports in 2006 (percent of respondent, n=54) figure 4: number of containers imported in 2006 (percent of respondent, n=54) fifty three percent of respondents were members of a trade organization or an association that has a focus on international wood products trade. when asked about their primary sources of information in selecting products and suppliers, e-mail communication was ranked first, followed by word of mouth, websites, international tradeshows, and sales representative (figure 5). direct mailing was ranked last from a list of 12 information and communication sources. bandara & vlosky /journal of tropical forestry and environment vol. 2, no. 02 (2012) 49-62 55 figure 5: ranking of sources of information utilized by the u.s. wood products importers (n=54) 3.2. wood products imports figure 6 shows the types of wood products imported by respondents. softwood lumber was the main product imported by most respondents (19% of respondents) followed by millwork and mouldings, hardwood plywood, hardwood lumber, softwood plywood and flooring. in order to identify major exporters to the u.s., respondents were asked to rank the top ten suppliers that they imported wood products from by purchase value. respondents purchased wood products from variety of supplier countries. according to the respondents, brazil was the top wood product supplier by purchase value in 2006 followed by chile, china and canada. according to the results, there were 4 tropical countries among the top ten exporters to the u.s. (figure 7). when asked about the quality of wood products originate from major supplier countries, brazilian wood products were ranked highest (22% of respondents) followed by chile (18%) and finland (10%). the u.s. importers had moderate to low perception on wood products originated from tropical countries such as bolivia, ghana, india, indonesia, malaysia, philippines and taiwan. the u.s. importers were especially concerned about wood products they import meeting the required phytosanitary standards. almost 57% of respondent companies request their suppliers to conduct tests and remediation for insects and other pests and 47% require tests for microbes from their suppliers. approximately 53% of the respondents (n=25) stated that they are planning to diversify their wood products imports in the next 5 years. hardwood plywood, doors, furniture, edge glued panels, agrofiber panels, plastic composites, lvl, rubber wood lumber, engineered value added products, hardwood decking, hardwood flooring, euclyptus plywood and lumber, glulam beams, and pallets were among the frequently mentioned products considered by respondents in diversifying their imports. when asked about their intentions on diversifying timber species they import in the next 5years, out of 46 respondents, 43% (n=20) said they are planning to do so. beech, alder, red pine, african mahogany, eucalyptus, big-leaf mahogany, blood-wood, japela, and ipe were mentioned as potential species for diversifying. about 60% bandara & vlosky /journal of tropical forestry and environment vol. 2, no. 02 (2012) 49-62 56 of the respondents further stated that they are currently seeking new sources/countries of supply for imported wood products. figure 6: wood products imported in 2006 (n=54, multiple responses possible) figure 7: origin of wood products imported by purchase value as ranked by the respondents (percent of respondents, n=54) bandara & vlosky /journal of tropical forestry and environment vol. 2, no. 02 (2012) 49-62 57 3.3. supplier selection criteria one of the main objectives of this study was to identify factors that the u.s. importers deem important in selecting foreign wood product suppliers. respondents were asked to indicate the level of importance in a 1 to 5 likert scale for a set of 21 possible factors or criteria used in supplier evaluation. product quality, long term customer relationships, on-time delivery of orders, fair prices, and supplier reputation were the factors deemed highly important by respondents in selecting their suppliers. environment related factors were ranked as moderately important by the respondents with criterions “provide certified products” and “products from sustainably managed forests” receiving mean scores of 3.58 and 3.51 respectively (table 1). table 1: means and standard deviations for foreign buyer selection criteria criterion responders (n) mean std. deviation product quality 52 4.79 0.49 long term customer relationship 52 4.71 0.49 on time delivery 52 4.63 0.56 fair prices 53 4.57 0.75 supplier reputation 51 4.35 0.77 customer relationship 51 4.31 0.91 customer service 50 4.28 0.73 fast response to inquires 50 4.16 0.77 knowledgeable sales people 50 3.92 1.16 supplier speaks english 51 3.69 1.30 provide certified products 52 3.58 1.32 product from traditional species 50 3.52 1.15 products from sustainably managed forests 51 3.51 1.33 fast delivery 48 3.42 1.18 warranty 49 3.27 1.29 computer capabilities 48 3.21 1.27 distribution capabilities 48 2.96 1.25 product design 48 2.9 1.39 uniqueness 50 2.8 1.36 marketing skills 49 2.65 1.22 products from lesser used species 49 2.53 1.00 items represented in table 1 may represent different underlying dimensions in supplier selection. to explore these dimensions, factor analysis with principal axis factoring was performed. the kaisermeyer-olkin test statistic of 0.63 suggested the sampling adequacy to perform a factor analysis while significance (p = 0.001) for bartlett’s test of sphericity indicated that selected measurement items are correlated. only items with loadings greater than 0.5 were retained for analysis, i.e. 18 items were retained (table 2). accordingly, five factors were extracted from principal axis factoring accounting for almost 68% of the total variance. these factors/dimensions were named “certification and marketing”, “product attributes”, “customer relations”, “quality products supply” and “timber species and supplier reputation” respectively based on factor loadings from criterion items (table 2). 3.4. perceptions on environmentally certified forest products at the time that the study was conducted, 61% of respondents (out of n = 44) said that they import certified wood products, while the rest (39%) did not. respondents were also asked about their company’s approximate percentage of certified wood products sales of their total wood products sales. for the 13 respondents that answered this question, certified products did not exceed 29% of the total wood product bandara & vlosky /journal of tropical forestry and environment vol. 2, no. 02 (2012) 49-62 58 sales by value. more than half of the respondents (51%) were accepting fsc certification followed by sfi (21%), iso 14000 (11%), and pefc (7%) certification. when asked about their involvement in certification promotion, only 19% of respondents who imported certified products (n=27) said their company actively promotes its products as certified, while 30% (n=8) have requested their non-certified foreign suppliers to become certified. another 26% (n=7) said their certified products carry eco-labels, 41% (n=11) said they do not, while 33% (n=9) were unsure if their certified wood products carry an ecolabel. table 2: underlying dimensions of supplier selection extracted from factor analysis variable factor certification and marketing product attributes customer relations quality products supply timber species and supplier reputation products from sustainable managed forests 0.893 -0.041 0.089 0.151 0.058 ability to provide certified products 0.837 0.263 -0.029 -0.018 -0.002 uniqueness 0.614 0.365 0.446 -0.055 0.273 distribution capabilities 0.555 0.445 0.269 0.178 0.162 marketing skills 0.508 0.434 0.404 -0.029 0.147 warranty 0.096 0.852 0.034 0.160 -0.003 design 0.300 0.712 0.062 -0.058 0.330 fast delivery 0.330 0.546 0.168 0.362 0.071 supplier speaks english 0.024 0.089 0.844 -0.156 0.086 long term customer relationship -0.007 -0.356 0.738 0.154 0.290 computer capabilities 0.262 0.277 0.713 0.178 0.055 on time delivery 0.000 0.110 0.052 0.897 -0.043 quality 0.235 -0.031 -0.124 0.730 0.330 consistent supply -0.033 0.184 0.214 0.625 0.139 products from traditional species 0.054 -0.085 0.273 0.012 0.820 supplier reputation -0.026 0.163 -0.088 0.288 0.644 products from lesser used species 0.142 0.296 0.372 -0.046 0.579 fast response to my inquiries 0.187 0.323 0.007 0.260 0.540 using a 5-point scale (1 = strongly disagree; 3 = somewhat agree; 5 = strongly agree), respondents were asked to state their level of agreement to different statements related to certification. summary results are provided in table 3. mean scores did not exceed 3.25 for any of the statements. results indicate that respondents are unlikely to pay price premiums for certified products (table 3). table 3: respondents’ mean scores for statements on certification statement responders (n) mean std. deviation certified products help to protect environment 44 3.25 1.118 certified products help my company reach diversified markets 43 3.08 1.187 if available, i would seek out for certified products 39 2.92 1.288 i would like to get information about forest certification 44 2.46 1.206 certified products can capture price premiums 42 2.43 1.099 i would pay a premium for certified products 44 2.08 1.096 bandara & vlosky /journal of tropical forestry and environment vol. 2, no. 02 (2012) 49-62 59 4. discussion and conclusions the present study provides a better understanding on the u.s. wood products import sector. study results better frame various import related issues and important aspects in wood products importing from the perspective of wood product importers in the u.s. when considered the value of sales, volume of imports, and number of employees, most of the respondents were small to medium scale firms in size, but major importers of wood products. softwood lumber was the leading wood product import category in terms of volume followed by hardwood lumber, hardwood plywood, and millwork and mouldings. according to the respondents, brazil, chile, and china were the large scale wood product suppliers to the u.s. market in terms of volume. however, trade reports for 2006-2007 indicate china, canada, brazil, chile, and mexico as the top wood products exporters to the u.s. (u.s. department of commerce, 2008). this may be attributed to the sample of wood products importers responded to the survey. from the importers’ perspective, brazilian wood products ranked first in terms of quality, followed by wood products from chile and finland. product quality, long term customer relationships, on-time delivery of orders, fair prices, and supplier reputation were the factors deemed highly important by respondents in selecting their overseas suppliers. therefore, it is highly important that wood products exporters to the u.s. focusing on providing quality wood products in a timely mummer and maintaining better customer relationships to ensure sustainable business partnerships. according to factor analysis results, “superior product attributes”, “better customer relationships”, ‘efficient logistics/supply”, “reputation of the supplier and its products (species)” and “environmental claims associated with the product” can be recognized as the main dimensions that the wood products exporters should focus on, if they wish to achieve better success in the u.s. markets. results further indicate that u.s. wood products importers prefer electronic sources such as emails and websites as convenient sources of information, as well as means of communication with their foreign suppliers. hence, from the perspective of wood product suppliers, it is worth shifting to webbased driven advertising and communication strategies. in addition, timber products are increasingly traded via e-commerce in modern markets. however, word of mouth reputation, international tradeshows, and sales representative are still important sources of information. results indicate that majority of respondents (61%) are importing certified wood products. this can be attributed to the increased legislative restrictions on import of illegally sourced wood products, and pressure from environmental organizations, rather than due to the demand coming from consumer side (eia-global.org, 2008; perera et al, 2008). respondents were in disagreement with certified products capturing price premiums in the market, and were not in favour of paying price premiums for certified products. results further indicate that most respondents are not actively involved in promoting or marketing certified products. a study conducted by perera et al. (2008) on top 500 u.s. home center retailers found certified products being the only products available, and to improve the company’s image as the most cited reasons for purchasing/selling certified wood products rather than customer demand. results of the present study are also comparable with perera et al. (2008). fsc, sfi, and iso 14,000 were the most popular certification programs among respondents. despite the demand for certified products not coming from actual customers, it is likely that certification will continue to be an important factor in accessing u.s. markets due to direct and indirect regulations. hence it is advisable for wood product exporters to ensure the legality and source of their wood products, and certification may be an important option available to them. opportunities for tropical wood products exporters according to itto reports, the u.s. tropical lumber imports plunged by nearly half between 2008-2009 recession. however tropical lumber supply and demand in the u.s. have stabilized in 2010, and expected to remain the same (mongabay.com, 2010). recovering housing markets in the u.s. have bandara & vlosky /journal of tropical forestry and environment vol. 2, no. 02 (2012) 49-62 60 opened up new opportunities for tropical wood product exporters. moreover, lower cost, improved quality and efficient logistics have forced u.s. firms to source wood products offshore. after softwood lumber, hardwood plywood, millwork and mouldings, hardwood lumber, and wooden flooring were the main products imported by most respondents. in fact, these are among the major wood products imported to u.s. from tropical countries (ekström and goetzl, 2007). results further indicated that there were 4 tropical countries among the top ten exporters to the u.s. i.e. brazil, chile, honduras, and indonesia. wood products originated from brazil and chile were ranked highest in terms of quality by respondents. the success of tropical suppliers such as brazil and chile may be attributed to their capacity to supply quality products in sufficient volumes. however, u.s. importers rated wood products originated from tropical countries such as bolivia, ghana, india, indonesia, malaysia, philippines and taiwan as moderate (to low) in terms of quality. hence, these suppliers should focus on key supplier selection dimensions deemed important by u.s. importers. results further indicate that u.s. importers are looking to diversify their wood products as well as timber species imported. african mahogany, eucalyptus, big-leaf mahogany, blood-wood, japela, and ipe were mentioned as potential species for diversifying. hardwood plywood, hardwood flooring and decking, furniture, and tropical hardwood lumber products are likely to have better markets. since tropical wood species can compete successfully with u.s. domestic species because of their unique properties and aesthetics, exporters of above mentioned products may enjoy better success in the u.s. wood products markets (ekström and goetzl, 2007). in order to successfully accessing the u.s. markets, suppliers of tropical wood products need to further understand other trade and legal requirements such as meeting required phytosanitary standards, and documentation to authenticate the legality and source of wood. tropical lumber exporters may need to be knowledgeable about the national hardwood lumber association (nhla) grading standards. as wood products manufacturing sectors of many tropical countries are dominated by small to medium scale manufacturers, the u.s. tropical wood products market is off-limits largely due to the scale of manufacturing, marketing complexity, and capital requirements (fao 2007). hence, greatest opportunities for such countries seem to exist in value-added niche markets especially for outdoor hardwood plywood, furniture, wood flooring and decking, and mouldings and millworks. small to medium scale tropical wood products manufacturers shall further look into building strong customer relationships with importers to acquire specific market information and product requirements so that they can tailor-made products for specific niche markets (perera et al, 2006). partnering with other local manufacturers of similar capacity is another option to meet volume requirements in accessing certain u.s. tropical wood products markets. study limitations and avenues for future research the data for this study was collected during 2007-2008 period, which is just before the beginning of recession in the u.s. economy. the u.s. tropical timber imports market was also affected by the recession. hence, the validity of findings of this study may be limited due to the dynamic nature of markets. yet, this study will be an important reference in comparing and assessing trends in the u.s. tropical timber imports market, as handful of previous studies can be found in literature on analysis of u.s. tropical timber imports markets. aspects such as u.s. importers’ foreign supplier selection criteria, species preferences, product categories as well as interest on certified tropical timber are relatively less explored by previous research. the u.s. importer perceptions on tropical timber products are important as demand for certified wood seems to gradually increase. this study further provides insights to u.s. tropical timber imports markets which are important from tropical timber exporters’ perspective. on the other hand, certain reports indicate that tropical lumber supply and demand in the u.s. have stabilized, and indicate no severe changes in demand/preference in comparison to pre-recession levels (mongabay.com, 2010). bandara & vlosky /journal of tropical forestry and environment vol. 2, no. 02 (2012) 49-62 61 authors of the paper further believe that present study will provide numerous pathways for future research where future works can be streamlined to study each aspect covered by this study in a more detailed manner. periodical comparative studies are further recommended to understand market trends where present study can be used as a basis for comparison. references armstrong, j., 2011. the global wood products market. http://jim_armstrong.forestry.wvu.edu/r/download/91184. accessed july 2012. anderson, r.c., hansen, e.n., 2004. the impact of environmental certification on preferences for wood furniture: a conjoint analysis approach. forest products journal 54 (3): 42-50. buehlman, u., and schuler. a., 2009. the u.s. household furniture industry: status and opportunities. forest products journal. 59(9), 20-28. dillman, d. a., 2000. mail and internet surveys: the design method, second ed. john wiley & sons, inc., new york, nj. draffan, g., 2000. u.s. imports of chilean wood products, public information network. http:// www.endgame.org. accessed september 2007. eia-global.org., 2008. the u.s. lasey act frequently asked questions about the world’s first ban on trade in illegal wood. http://www.eia-global.org/lacey/p6.eia.laceyreport.pdf. accessed july 2012. ekström, h., goetzl, a., 2007. the us market for tropical wood products. itto tropical forest update, 17(2):3-6. fao, 2007. competitiveness of tropical timbers at the us market. http://foris.fao.org/preview/182810f84c01ba715f19b9660aa2b513ba9af2.pdf. accessed july 2012. fao, 2011. state of the world’s forests 2011, food and agriculture organization of the united nations, rome, 2011. flynn, b, 2012, global timber and solidwood market. highlights focus on asia 2012, 25th annual global forest & paper industry conference, pwc, vancouver, british columbia, may 12, 2012. fao, 2006. food and agricultural organization of the united nations , http://www.fao.org. accessed september 2007. globalwood.org, 2011. wood products prices in the u.s. http://www.globalwood.org/market/timber_prices_2009/aaw20110802f.html. accessed july, 2012. howard, j. l., and mckeever, d. b., 2012. u.s. forest products annual market review and prospects, 2008–2012. research note fpl-rn-0328. madison, wi: u.s. department of agriculture, forest service, forest products laboratory. huong. b.t., and dao, t., 2007. foreign agricultural service gain report (vm7088): vietnam: solid wood products update. united states department of agriculture, 2007. itto, 2011. tropical timber market report, international tropical timber organization, 16: 4. mongabay.com, 2010. tropical timber imports to the u.s. plunge, http://news.mongabay.com/2010/0215timber_imports.html#ixzz22vnrgkce. accessed july 2012. oskooee, m.b., chakrabarti, a., 2003. import competition, employment and wages in u.s. manufacturing, department of economics, university of wisconsin-milwaukee, milwaukee, wi, 53201, usa. ozanne, l.k., vlosky, r.p., 2003. certification from the u.s. consumer perspective: a comparison from 1995 and 2000. forest products journal. 53 (3), 13-21. perera, p., vlosky, r.p., amarasekera, h.s., and de silva, n., 2006. forest certification in sri lanka. forest products journal. 56, 5-11. perera, p., vlosky, r.p., hughes, g., and dunn, m., 2007. what do louisiana and mississippi nonindustrial private forest landowners think about forest certification?.southern journal of applied forestry. 31, 170-175. bandara & vlosky /journal of tropical forestry and environment vol. 2, no. 02 (2012) 49-62 62 perera, p., vlosky, r.p., hughes, g., and dunn, m., 2008. u.s. home center retailer attitudes, perceptions and behaviors regarding forest certification. forest products journal, 58, 21-25. pirc, a., and vlosky, r.p., 2010. a brief overview of the u.s. furniture industry, louisiana forest products development center working paper #89, louisiana state university agricultural center baton rouge, louisiana, usa. the 2007 big book, buyers and sellers directory of the forest products industry, u.s.a. 2007, random lengths. united nations, 2011. the unece/fao forest products annual market review, 2010-2011, united nations, geneva. u.s. department of commerce, 2008. available from http:// www.commerce.gov/ accessed on september, 2009. vlosky, r. p., gazo, r., cassens, d., and perera, p., 2009. changes in value-added wood product manufacturer perceptions about certification in the united states from 2002-2008. drvna industrija (wood industry), croatia, 60, 89-94. wood markets 2011, u.s. wood products imports in 2010, wood markets monthly international report highlights, 16, 4. 10 correspondence: cddangalle@zoology.cmb.ac.lk issn 2235-9362 online ©2022 university of sri jayewardenepura diversity and habitat preferences of moths (insecta: lepidoptera) in indikadamukalana, a lowland wet zone forest in sri lanka p. gunathunga1, c. d. dangalle1* and n. pallewatta1 1department of zoology and environment sciences, faculty of science, university of colombo, sri lanka date received: july 31, 2022 date accepted: october 28, 2022 abstract the moths (insecta, lepidoptera) of sri lanka have not been well studied and no comprehensive scientific study on their diversity has been carried out over the past 100 years. thus, establishing species richness and diversity of moths in different habitats of the island is important. the present study was carried out to investigate moth species diversity and habitat factors which can affect moths in indikadamukalana forest reserve situated in the wet zone of sri lanka. moth diversity of the forest was investigated for a period of approximately seven months in 2018, where two habitat types as forest edge and within forest were studied. transect line count method was used to sample diurnal moths and light traps were used to study nocturnal moths. aerial nets and fruit-baited traps were used to improve the sampling efficiency. weather parameters of the two habitat types were estimated using a potable weather station. a total of 138 moth species of 19 families were recorded, with forest edge habitat recording 18 families (91 species) and within the forest habitat recording 15 families (47 species). crambidae and erebidae were the most prominent families of moths found in both habitats of the forest. gelechiidae was recorded only from within the forest habitat while sphingidae, hepialidae, tortricidae and bombycidae were recorded only from the forest edge habitat. weather parameters between the two habitats did not depict a significant difference. maintenance of sri lanka’s biodiversity hotspot status lies within the wet zone of the country. thus, long term studies of moth communities of the wet zone are of vital importance. keywords: moths, indikadamukalana forest, forest habitats, species richness, sri lanka 1. introduction lepidoptera is the second largest order of class insecta and is found in all countries of the world except in the poles. it includes the micro-moths, which embraces the most primitive lineages of the lepidoptera; the macro-moths, which are the predominantly night-flying members of the order; and the butterflies and skippers (kristensen et al., 2007). there are 255,000 species of lepidoptera in the world belonging to 125 families. of these, 231,500 species are moths representing 119 families while only 23,500 species are butterflies and skippers (capinera, 2008). however, it has been reported that the sampling and identification of moths, especially in the tropical regions has so far been inadequate (kristensen et al., 2007), and this situation is unlikely to have changed even today. phytophagous insects, whose presence and abundance depends on particular plant species, thrive in tropical rainforests and high proportions of endemic and rare species have often been recorded (fiedler and schulze, 2004). tropical rainforests are believed to house a tremendous diversity of moths due to habitat heterogeneity and presence of a wide range of niches (jaroensutasinee et al., 2011), and certain studies have documented the moth species in tropical rain forests from different countries (brehm and fiedler, 1999; beck et al., 2002; beck et al., 2006; akite et al., 2015; nino et al., 2019). when considering the countries of tropical asia, moth species have been recorded from selected areas of the gunathunga et al. /journal of tropical forestry and environment vol.12. no. 01 (2022) 10-23 11 indian subcontinent, bhutan, pakistan and philippines (mathew and rahamathulla, 1995; irungbam et al., 2016; faiz et al., 2019; sebua and nuňeza, 2020). however, most of these studies have focused on only certain families of moths such as pyralidae, crambidae, erebidae, geometridae, arctiidae, saturnidae, and sphingidae, considering their economic importance, high species richness and large body size. however, mathew and rahamathulla (1995), who recorded the moth fauna in the lowland evergreen forests of silent valley, western ghats, disclosed the close resemblance between the moth fauna of india and sri lanka, and their origin from the countries from the oriental region. in sri lanka, a wide variety of moths representing 52 families that includes around 1911 species have been recorded (wijesekara and wijesinghe, 2003; kocak and kemal, 2012). however, despite their wide variety, moths have been poorly studied in sri lanka, a fact that is pertinent to other countries of asia as well. in sri lanka the last comprehensive scientific study on moths was done by g. f. hampson between 1892 – 1896 as a part of the “fauna of british india” series, with four volumes on moth taxonomy and diversity. the studies conducted since then have mainly focused on species of economic importance such as pest species, with studies on diversity and abundance of a few selected groups (jayaneththi, 2016). the recent invasions by the fall armyworm, spodoptera frugiperda, on maize cultivations in the dry zone of sri lanka, initiated several investigations on the life history characteristics and management of this moth (kasige et al., 2022a, 2022b). a few studies have focused on using moth larvae as hosts for rearing parasitoids and other biological control approaches (karunarathne et al., 2020; sammani et al., 2020; singhamuni et al., 2021). the moth diversity of the university of vavuniya premises and associated host plants have been recorded by wijerathna et al., (2021). however, though the nomenclature of moths has been updated, the local moth faunal lists have not been updated accordingly. current studies on moth fauna of sri lanka is therefore obstructed by the lack of knowledge (aluthwattha, 2013). moths have been identified as a forest-dependent insect group that has experienced significant declines in species richness and abundance in the last 20 – 40 years, and in need of repeated biodiversity monitoring even within protected and relatively intact forests (akite et al., 2015). the red lists developed by the international union for conservation of nature (iucn) is highly biased towards larger and better-studied taxa such as vertebrates, in view of the fact that data on the conservation status of insects are scarce (koh, 2007). majority of red lists for moth species have been developed for the countries of europe (fox et al., 2019; duffus and morimoto, 2022), and rarely for the countries of asia. in sri lanka, eventhough a butterfly conservation action plan (2014) has been developed for the taxonomy, distribution, legal and institutional aspects, and threats faced by butterflies, such action plans or lists for the conservation status of moths are unavailable. however, due to the highly dynamic nature of moth populations, driven by short lifecycles and sensitivity to environmental factors and thus susceptibility to extinction, it is imperative that data on their biology, distribution and habitat preferences be investigated. therefore, in this study we investigate the moth diversity of indikadamukalana lowland wet zone forest of sri lanka in order to record the moth diversity in two habitat types (forest edge and within the forest) of the forest and to study the relationship between species diversity and selected habitat parameters. 12 2. methodology 2.1 study area the study was conducted in indikadamukalana forest reserve situated in the wet zone of sri lanka. the forest lies adjacent to the seethawaka wet zone botanic gardens and is important in providing seeds to the arboretum (ranwala et al., 2017). it harbours a high species diversity of butterflies, rich in endemic species (peiris et al., 2020). two habitat types with different habitat structures were selected: within the forest habitat of indikadamukalana forest (6090’19”n; 80016’88”e) and the edge habitat of indikadamukalana forest (60 90’17”n; 80017’01”e) (figure 01). in selecting the two habitat types different vegetational types representing micro-habitats such as grasses, shrubs, understory and canopy cover were all considered as within forest habitats, while the boundary of the forest with associated home gardens were considered as the forest edge habitat. figure 01: location of indikadamukalana forest reserve and study sites. the two study sites (forest edge site and forest site) are indicated as transects where sampling was conducted. imfr – indikadamukalana forest reserve 2.2 field sampling methods sampling was conducted in two habitat types of the forest from 24 february 2018 to 15 september 2018 for a period of approximately seven months. in each habitat two 100 m line transects covering the vegetation communities were established where each transect covered an area of 100 m × 40 m. sampling was carried out for two consecutive days including a single night in the last week of each month so that both diurnal and nocturnal moths were sampled. thus, sampling was carried out for a total of 16 days, from 8.00 am to 11.00 am and 3.00 pm to 6.00 pm for diurnal moths and from 6.00 pm to 10.00 pm and 4.00 am to 6.00 am for nocturnal moths. moth species were identified using available field guides (jayawardana and jayasinghe, 2016) and unidentified moth species were collected using standard techniques for subsequent identification in the laboratory using taxonomic keys. gunathunga et al. /journal of tropical forestry and environment vol.12. no. 01 (2022) 10-23 13 for nocturnal moth sampling, light traps were made using 22 w uv light bulbs powered with 12 v batteries (choi et al., 2009; choi and an, 2013) and a white reflective sheet of 2.5 m x 2 m hung at a height of 3m. two light traps were placed along each transect with a 40 m distance in between the light traps (schmidt and roland, 2006). at the same time nocturnal moths found inside the houses situated in the edge habitat falling in to the area covered by the transects were sampled using insect nets. for diurnal moth sampling a line transect survey was carried out where insect nets were used where necessary to collect unidentified moth species for further investigation. fruit-baited traps were placed for both diurnal and nocturnal moths. as fruits, banana (musa sp.), papaya (carica papaya) and star fruit (averrhoa carambola) were used according to their seasonal availability. the fruit-baited trap was made by placing a cup with cut pieces of ripe fruits (250 g) at the bottom of a net which was made in a cylindrical shape (120 cm long net) leaving a gap for the moths to enter into the net from the bottom. two traps per habitat were hung on a tree at a height of 5m from the ground in the pre-established line transects in areas where light traps were not placed. the trap was hung for 24 hours and the observations were recorded from 8.00 am to 11.00 am in the morning, 3.00 pm to 6.00 pm in the evening, 6.00 pm to 10.00 pm and 4.00am to 6.00 am in the night at half an hour intervals. 2.3 identification of moths moth identification was done in the laboratory using a dissecting microscope and with the use of standard keys and descriptions provided in hampson (1892, 1894, 1895, 1896), bell and scott (1937) and borror et al. (1954). due to high species diversity and the lack of taxonomic keys with the exception of the taxonomic keys to the moths in the south asian region in “fauna of british india” most moths were only possible to be identified up to family level. 2.4 measurement of weather parameters in this study, the variation of moth diversity with weather parameters in the two habitat types were taken into account. therefore, weather parameters including ambient temperature, relative humidity, wind speed (davis vantage pro 2 weather station); light intensity (lux meter); rainfall (meteorological department, sri lanka) were measured. measurements were taken at the time of moth collection, and four readings per parameter, per month for diurnal moth locations, and two readings per parameter, per month for nocturnal moth locations were recorded. 2.5 data analysis one-way analysis of variance (anova) with tukey’s comparison was performed using minitab version 17.0 to observe whether there was a significant difference in weather parameters between the two habitats during the seven months of data collection. 3. results 3.1 diversity of moths in the habitats of the indikadamukalana forest a total of 138 species of moths representing 19 families were identified from indikadamukalana rainforest. however, some species were not identified up to the species level and only up to the family level. the edge habitat of the indikadamukalana forest had a higher diversity of moths than the habitat within the forest and 91 species of 18 families were found in different micro-habitats of the forest edge habitat. the habitat within the forest housed 47 species of moths belonging to 15 families. the family composition of moths in the two habitats were closely similar (table 01, figure 02, figure 03). 14 table 01: moths recorded from the habitats of indikadamukalana forest reserve family species recorded from the edge habitat species recorded from within the forest 1. notodontidae 9 unidentified sp. 2 unidentified species 2. erebidae eublemma sp. syntamoides imaon nepita conferta nepita conferta syntomeida sp. artaxa sp. amata passalis erebus ephesperis mocis undata 7 unidentified sp. 7 unidentified sp. 3. noctuidae brithys crini 1 unidentified sp. 2 unidentified sp. 4. tortricidae 1 unidentified sp. 5. sesiidae 1 unidentified sp. 1 unidentified sp. 6. hepialidae 1 unidentified sp. 7. tineidae 6 unidentified sp. 1 unidentified sp. 8. crambidae ancylolomia japonica bocchoris inspersalis metoeca foedalis diaphania indica tatobotys biannulalis pyrausta panopealis omiodes diemenalis spoladea recurvalis cnaphalocrocis bilinealis 18 unidentified sp. metoeca foedalis tatobotys biannulalis pleuroptya iopasalis 7 unidentified sp. 9. pyralidae 7 unidentified sp. 6 unidentified sp. 10. geometridae hypomecis transcissa hemithea sp. 8 unidentified sp. 8 unidentified sp. 11. uraniidae dysaethria lilacina 1 unidentified sp. 1 unidentified sp. 12. lasiocampidae 2 unidentified sp. 1 unidentified sp. 13. thyrididae 1 unidentified sp. 1 unidentified sp. 14. sphingidae daphnis nerri 1 unidentified sp. 15. bombycidae 1 unidentified sp. 16. eupterotidae 1 unidentified sp. 2 unidentified sp. 17. zygaenidae 1 unidentified sp. 1 unidentified sp. 18. drepanidae 2 unidentified sp. 2 unidentified sp. gunathunga et al. /journal of tropical forestry and environment vol.12. no. 01 (2022) 10-23 15 figure 02: moth species of selected families recorded from the edge habitat of indikadamukalana forest figure 03: moth species of selected families recorded from within the forest habitat of indikadamukalana forest 16 in both habitats – edge and within the forest, the highest species richness of moths were represented by family crambidae followed by family erebidae. in the forest edge habitat, family notodontidae occupied the third position with family geometridae in the fourth position whereas in the habitat within the forest, family geometridae occupied the third position followed by family pyralidae. the percentage abundance of families crambidae and erebidae within the forest habitat was lower than in the habitat at the forest edge. however, species richness of family geometridae is highest within the forest habitat with edge habitat occupying approximately only half of the species of family geometridae within the forest (figures 04 and 05). family tortricidae and tineidae were the least abundant moth families observed in edge and within the forest habitats respectively. according to figure 06, 14 families of moths were common to both habitats of indikadamukalana forest. family gelechiidae was only recorded from within the forest habitat of indikadamukalana while families tortricidae, bombycidae, sphingidae and hepialidae were recorded only from the edge habitat of indikadamukalana. figure 04: species richness of moth families in the edge habitat of indikadamukalana forest figure 5: species richness of moth families in the habitat within indikadamukalana forest gunathunga et al. /journal of tropical forestry and environment vol.12. no. 01 (2022) 10-23 17 figure 6: degree of overlap in the occurrence of moth families in the two habitats at indikadamukalana forest 3.2 vegetation in the habitats of the indikadamukalana forest plant diversity and heterogeneity was high in the edge habitat when compared with the habitat within the forest. the edge habitat consisted of large and small trees such as godapara (dillenia retusa), jak (artocarpus heterophyllus), rambutan (nephelium lappaceum), papaya (carica papaya), albizia; shrubs such as rose apple (szygium jambos), tea (camellia sinensis), bovitiya (osbeckia octandra); herbs such as bandura wel (nepenthes distillatoria) and aquatic plants such as blue lotus (nymphaea nouchali). comparatively the habitat within the forest was dominated and limited to large trees such as kithul (caryota urens), mahogany (swietenia mahogany), ginikuru (alstonia macrophylla), hal (vateria copallifera) and wal karabu (fagraea fragrans). 3.3 effect of weather variables on moth diversity when considering the climate of the two habitats, significant differences were not evident in any of the parameters diurnally or nocturnally (table 02). therefore, differences in moth species diversity in the edge and within forest habitats may not have been influenced by variations of the climate. table 2: climate parameters of the two habitats in indikadamukalana forest (mean ± std. dev.) habitat parameter forest edge within forest nocturnal (n = 12) diurnal (n = 24) nocturnal (n = 12) diurnal (n = 24) temperature (0c) 26.08 ± 1.84 27.74 ± 1.53 25.90 ± 0.53 27.31 ± 1.88 relative humidity % 89.00 ± 0.03 83.38 ± 0.06 90.20 ± 0.01 81.25 ± 0.09 wind speed (kmh-1) 0.20 ± 0.45 0.89 ± 1.61 0.60 ± 1.34 0.83 ± 1.08 rainfall (mm) 6.88 ± 7.88 7.95 ± 8.55 light intensity (klux) 17.19± 26.10 5.87 ± 7.73 18 4. discussion tropical rain forests harbor a large amount of herbivorous insects, particularly comprising of phytophagous coleoptera, and lepidoptera such as butterflies and moths (fiedler and schulze, 2004). however, habitat loss due to forest destruction and non-sustainable forest use, especially in tropical forests around the equator have resulted in large diversity losses of these insects (beck et al., 2002). when considering the lepidoptera, moths maybe more affected by the habitat changes than the butterflies, as they are more ecologically diverse and at least 15 times more taxonomically diverse than butterflies (wagner et al., 2021). the substantial decline of moths have been reported for countries such as the united kingdom, united states, germany, sweden, india, netherlands, siberia and new zealand (dar and jamal, 2021), but vaguely for biodiversity rich tropical islands such as sri lanka. in sri lanka, regardless of studies concerning the decline in moth diversity, surprisingly, even the diversity of moths have not been investigated for more than a 100 years. in this study we investigated the moth diversity in a tropical wet zone forest of the country with the intention of recording the moth species found in the wet zone forest, species rich families, habitats with high diversity and possible weather parameters of the habitats affecting moth diversity. one hundred and thirty-eight moth species were recorded from indikadamukalana forest which represented 7.22% of the 1911 moth species that have been recorded from sri lanka. the edge habitats of the forest had a high moth species richness (91 species) when compared with the habitats within the forest (47 species). however, the moth family compositions of the two habitats were more or less similar with 14 families (~74%) being common to both habitats. the pyraloidea (geometridae and pyralidae) species richness was high within the forest, and gelechiidae were restricted to the forest. tortricidae, sphingidae, bombycidae and hepaliadae were only found in the edge habitats. families crambidae and erebidae which are large moth families with worldwide distribution, were the prominent families of both the habitats. weather parameters did not seem to affect moth diversity of the two habitats as significant differences of parameters were not evident between the two habitat types. however, microclimatic conditions such as air and soil temperatures, wind velocity, short-wave radiation, and air and soil moisture are known to be significantly different between forest edges and habitats inside the forest, with high variability of the parameters at the forest edge (chen et al., 1993). therefore, further studies including long-term investigations and recordings of soil parameters are suggested. previous studies on species richness of moths reveal that some are on par with the current study and some have deviations. beck et al., 2002, fiedler and schulze, 2004 and sutrisno, 2010, have revealed that moth species richness is high in undisturbed primary forests than disturbed habitats and have suggested possible reasons for this observation. beck et al. (2002), suggests that old-growth forests have well-developed undergrowth to support a rich diversity of moth species, whereas disturbed secondary forests and farmland sites lack undergrowth vegetation and thus supports a less number of moth species. fiedler and schulze (2004) suggest that a plethora of moth species may exist in undisturbed habitats due to the prevalence of host plants and a variety of woody plants. according to sutrisno (2010), the green canopy of primary forests provide refuge for many moth species. these studies particularly focus on family geometridae, and affirms that the species diversity tends to decrease at the disturbed edges of forest reserves when compared with the habitats within the forests. a similar outcome was also revealed in the present study, where the edge habitats had a low number of geometrid species when compared with the habitats within the indikadamukalana forest. however, several studies suggest that forest edges support a higher number of moth species by providing habitat heterogeneity, and that moth species richness in such habitats are higher than that of forest sites (brehm and fiedler, 1999; hawes et al., 2009). brehm and fiedler (1999) suggests that the high diversity may only be due to the immigration of moth species to disturbed sites from adjacent intact forests, whereas, hawes et al. (2009) suggests that the alternative land uses such as exotic tree plantations can support a substantial level of moth diversity. further, nino et al. (2019) reports that gunathunga et al. /journal of tropical forestry and environment vol.12. no. 01 (2022) 10-23 19 moths at the forest edge are significantly larger than those of the forest interior due to more mobility and better tolerance to desiccating conditions. a greater proportion of the larger moths are females that produce more offspring ensuring species survival (nino et al., 2019). forest edges are transition areas between different habitats in the same ecosystem created for settlements, agriculture, logging or by natural causes (laurance et al., 2007). alterations in environmental conditions, vegetation structure and composition and altered biotic interactions such as predation and parasitism in edge habitats cause changes in species diversity and abundance which is termed as the “edge effect” (zurita et al., 2012). in the present study, species richness of moths were higher at the forest edge compared to the habitats within the forest which may be due to differences in vegetation composition and biotic interactions between the moths and other animals. thus, plant diversity and heterogeneity may have been high in the edge habitat compared to the habitat within the forest resulting a higher diversity of moth species. however, biotic interactions between moths and other animals were not studied in the present study. in the present study crambidae and erebidae were the most speciose families in the forest habitats, a fact which has also been observed in forests elsewhere in the world. crambidae and erebidae were the most species rich moth families in the forest ecosystems of nilgiri hills, tamil nadu, india (moinudheen and sivasankaran, 2020), the warm-temperate forests of hyogo prefecture, japan (funamoto and sugiura, 2016), and keoladeo national park at bharatpur, india (trigunayat and trigunayat, 2021). the variety of different habitats found within the forest and forest edges may have promoted the species richness of the ecologically diverse crambidae and erebidae. further, larvae of many crambidae are known to be aquatic or semi-aquatic and live in stems or roots, or exposed leaves of aquatic plants (pabis, 2018). the presence of such habitats in the forest edges of indikadamukalana may have contributed to the higher numbers of crambidae in these habitats when compared to habitats within the forest. the occurrence of moths of families tortricidae, sphingidae, hepialidae and bombycidae only from the forest edge may be due the host plant interaction of the moths and their evolutionary adaptations. moths of family sphingidae are known to be associated with orchid varieties in home gardens (kitching, 2002), while species of family tortricidae are usually pests of tea, nuts and fruit varieties (johnson, 2013; maniania et al., 2017; nakai and lacey, 2017). family bombycidae harbours moth species that are pests of jackfruit (navasero et al., 2013) that are abundant in home gardens and moths of hepialidae are generalists that feed on a variety of plants (neilsen et al., 2000). however, their adaptations to disturbed habitats such as forest edges reveal that, certain taxonomic subgroups within these families may react to habitat disturbances differently, a fact which was not considered in the present study. according to beck et al. (2006), smerinthinae species of family sphingidae decreases with habitat disturbance, whereas species of macroglossinae of the same family thrive in disturbed habitats. however, as a whole the moths of family sphingidae are considered as an exceptional group of insects where many species are well adapted to survive in a changing environment dominated by cultivated areas and secondary forests (schulze and fiedler, 2003). finally, the study reports a rich diversity of moth species from the tropical wet zone forest, indikadamukalana, of sri lanka. the edges of the forest had a high species richness of moths than the habitats within the forest, possibly due to habitat heterogeneity and differences in vegetation. the composition of the moth families of the two habitats were closely similar, with the exception of a few groups. however, endemic species of moths were not recorded from the investigated sites of the indikadamukalana forest as expected. forest habitats of many countries are known to harbor unique sets of endemic moths such as in the native forests of azores, portugal (borges et al., 2018), western himalayan forests of india (sanyal et al., 2017), and rain forests of costa rica (rabl et al., 2019). the shortfall for the absence of endemic moth species in indikadamukalana may be due to the inability of identifying many species to the lowest taxonomic level. nevertheless, it is the first time a detailed investigation has been conducted on the moth fauna of sri lanka. further studies addressing the 20 limitations and drawbacks of the current study will benefit the conservation of moth assemblages and their habitats in the future. such studies are imperative given the extremely rich insect diversity of the country. acknowledgements we wish to thank the department of wildlife conservation and forest department for providing permits necessary for field work. we are grateful to prof. siril wijesundara, national institute of fundamental studies, kandy, sri lanka for his permission and support during the field work in indikadamukalana forest reserve. we thank the university of colombo, sri lanka for financial assistance and the department of zoology and environment sciences, university of colombo for provision of laboratory facilities and assistance. references akite, p., telford, r.j., waring, p., akol, a.m., vandvik, v., 2015. temporal patterns in saturnidae (silk moth) and sphingidae (hawk moth) assemblages in protected forests of central uganda. ecology and evolution, 5(8): 1746-1757. aluthwattha, s.t., 2013. family saturniidae (insecta: lepidoptera) of sri lanka: an overview. lepcey – the journal of tropical asian entomology, 2(1): 1-11. beck, j., schulze, c.h., linsenmair, k.e., fiedler, k., 2002. from forest to farmland: diversity of geometrid moths along two habitat gradients on borneo.journal of tropical ecology, 18: 3351. beck, j., kitching, i.j., linsenmair, k.e., 2006. effects of habitat disturbance can be subtle yet significant: biodiversity of hawkmoth-assemblages (lepidoptera: sphingidae) in southeastasia. biodiversity and conservation, 15(1): 465-486. bell, t.r.d., scott, f.b., 1937. sphingidae, in: blanford, w.t., (ed.), the fauna of british india, including ceylon and burma vol. 5. taylor and francis, fleet street, london, pp.1638. biodiversity secretariat , ministry of environment & renewable energy. 2014. butterfly conservation action plan of sri lanka. colombo: bds. borges, p.a.v., santa-rita, j.v.p., nunes, r., danielczak, a., hochkirch, a., amorim, i.r., lamelaslopez, l., karsholt, o., vieira, v., 2018. species conservation profile of moths (insecta, lepidoptera) from azores, portugal. biodiversity data journal. 6. borror, d.j., triplehorn, c.a., johnson, n.f., 1954. an introduction to the study of insects, sixth ed. saunders college publishing, united states. brehm, g., fiedler, k., 2005. diversity and community structure of geometrid moths of disturbed habitat in a montane area in the ecuadorian andes. journal of research on the lepidoptera. 38: 1-14. capinera, j.l., 2008. encyclopedia of entomology, second ed. heidelberg, germany. chen, j., franklin, j.f., spies, t.a., 1993. contrasting microclimates among clearcut, edge, and interior of old-growth douglas-fir forest. agricultural and forest meteorology. 63(3-4): 219237. choi, s.w., an, j.s., 2013. what we know and do not know about moth diversity from seven-yearmonitoring in mt. jirisan national park, south korea. journal of asia-pacific entomology. 16(4): 401-409. choi, s.w., park, m., kim, h., 2009. differences in moth diversity in two types of forest patches in an agricultural landscape in southern korea – effects of habitat heterogeneity. journal of ecology and environment. 32(3): 183-189. dar, a.a., jamal, k., 2021. the decline of moths globally: a review of possible causes. munis entomology & zoology. 16(1): 317-326. duffus, n.e., morimoto, j., 2022. current conservation policies in the uk and ireland overlook endangered insects and are taxonomically biased towards lepidoptera. biological conservation. 266. gunathunga et al. /journal of tropical forestry and environment vol.12. no. 01 (2022) 10-23 21 faiz, a.u.h., hassan, m.u., bagaturov, m.f., tariq, g., faiz, l.z., 2019. diversity of moths in some selected areas of district bagh, azad-jammu & kashmir. journal of bioresource management. 6(1): 27-35. fiedler, k., schulze, c.h., 2004. forest modification affects diversity (but not dynamics) of speciose tropical pyraloid moth communities. biotropica. 36(4): 615-627. fox, r., harrower, c.a., bell, j.r., shortall, c.r., middlebrook, i., wilson, r.j., 2019. insect population trends and the iucn red list process. journal of insect conservation. 23: 269278. funamoto, d., sugiura, s., 2016. settling moths as potential pollinators of uncaria rhynchophylla (rubiaceae). european journal of entomology. 113: 497-501. hampson, g.f., 1892. moths, in: blanford, w.t., (ed.), the fauna of british india, including ceylon and burma vol. 1. taylor and francis, fleet street, london, pp. 1-527. hampson, g.f., 1894. moths, in: blanford, w.t., (ed.), the fauna of british india, including ceylon and burma vol. 2. taylor and francis, fleet street, london, pp. 1-609. hampson, g.f., 1895. moths, in: blanford, w.t., (ed.), the fauna of british india, including ceylon and burma vol. 3. taylor and francis, fleet street, london, pp. 1-546. hampson, g.f., 1896. moths. in: blanford, w.t., (ed.), the fauna of british india, including ceylon and burma vol. 4. taylor and francis, fleet street, london, pp. 1-594. hawes, j., da silva motta, c., overal, w.l., barlow, j., gardner, t.a., peres, c.a., 2009. diversity and composition of amazonian moths in primary, secondary and plantation forests. journal of tropical ecology. 25(3): 281-300. irungbam, j.s., chib, m.s., wangdi, k., 2016. taxonomic review of the superfamily pyraloidea in bhutan (lepidoptera). journal of asia-pacific biodiversity. 9(3): 355-382. jaroensutasinee, m., pheera, w., ninlaeard, r., jaroensutasinee, k., choldumrongkul, s., 2011. weather affecting macro-moth diversity at khao nan national park, thailand. walailak journal. 8(1): 21-31. jayaneththi, h.b., 2016. note on butterfly-moth tetragonus catamitus geyer, 1832 (callidulidae) in wet zone, sri lanka. naturalist journal of ecology and nature. 8: 26-28. jayawardana, c.n., jayasinghe, h.d., 2016. colombo wetland moths. sri lanka butterfly conservation society, malwana, sri lanka. johnson, j., 2013. pest control in postharvest nuts, in: harris, l. (ed.), improving the safety and quality of nuts. woodhead publishing series, united states, pp. 56-87. karunarathne, e.v.u.p., dissanayaka, d.m.s.k., wijayaratne, l.k.w., 2020. development and evaluation of diets for rearing corcyra cephalonica (stainton) (lepidoptera: pyralidae) using readily-available materials. rajarata university journal. 5(2): 79-85. kasige, r.h., dangalle, c.d., pallewatta, n., perera, m.t.m.d.r., 2022a. egg cluster characteristics of fall armyworm, spodoptera frugiperda (lepidoptera: noctuidea) in sri lanka under laboratory conditions. the journal of agricultural sciences – sri lanka. 17(1): 200-210. kasige, r.h., dangalle, c.d., pallewatta, n., perera, m.t.m.d.r., 2022b. laboratory studies of larval cannibalism in same-age conspecifics of fall armyworm, spodoptera frugiperda (j. e. smith) (lepidoptera, noctuidea) in maize. tropical agricultural research & extension. 25(1): 7986. kitching, i.j., 2002. the phylogenetic relationships of morgan’s sphinx, xanthopan morganii (walker), the tribe acherontiini, and allied long-tongued hawkmoths (lepidoptera: sphingidae, sphingine). zoological journal of the linnean society. 135(4): 471-527. kocak, a.o., kemal, m., 2012. preliminary list of the lepidoptera of sri lanka. cesa news. 79: 1-59. koh, l.p., 2007. impacts of land use change on south-east asian forest butterflies: a review. journal of applied ecology. 44: 703-713. 22 kritensen, n.p., scoble, m.j., karsholt, o., 2007. lepidoptera phylogeny and systematics: the state of inventorying moth and butterfly diversity. zootaxa. 1668(1): 699-747. laurance, w.f., nascimento, h.e.m., laurance, h.g., andrade, a., ewers, r.m., harms, k.e., luizao, r.c.c., ribeiro, j.e., 2007. habitat fragmentation, variable edge effects, and the landscape-divergence hypothesis. plos one. 10: 1-8. maniania, n.k., ekesi, s., dolinski, c., 2017. entomopathogens routinely used in pest control strategies: orchards in tropical climate, in: lacey, l.a. (ed.), microbial control of insect and mite pests. ip consulting international ,yakima, united states, pp. 269-278. mathew, g., rahamathulla, v.k., 1995. biodiversity in the western ghats – a study with reference to moths (lepidoptera: heterocera) in the silent valley national park, india. entomon. 20(2): 25-33. moinudheen, n., sivasankaran, k., 2020. preliminary study of moth (insecta: lepidoptera) in coonoor forest area from nilgiri district tamil nadu, india. international journal of scientific research in biological sciences. 7(3): 52-61. nakai, m., lacey, l.a., 2017. microbial control of insect pests of tea and coffe, in: lacey, l.a. (ed.), microbial control of insect and mite pests. ip consulting international, yakima, united states, pp. 223-231. navasero, m.v., navasero, m.m., de roxas, m.c.l., calumpang, s.m.f., 2013. occurrence of the moraceae-feeding bombycid, trilocha varians (walker) (bombycidae, lepidoptera) as pest of jackfruit and some ornamental species of ficus in the philippines. journl of the international society for southeast asian agricultural sciences. 19(2): 41-48. nielson, e.s., robinson, g.s., wagner, d.l., 2000. ghost-moths of the world: a global inventory and bibliography of the exoporia (mnesarchaeoidea and hepialoidea) (lepidoptera). journal of natural history. 34(6): 823-878. nino, l.m.j., mortter, r., brehm, g., 2019. diversity and trait patterns of moths at the edge of an amazonian rainforest. journal of insect conservation. 23(4): 751-763. pabis, k., 2018. what is a moth doing under water? ecology of aquatic and semi-aquatic lepidoptera. knowledge and management of aquatic ecosystems. 419(42). peiris, m.u.h., dangalle, c.d., pallewatta, n., wijesundara, s., 2020. diversity of butterflies in different habitat types of seethawaka wet zone botanic gardens and indikadamukalana forest reserve of sri lanka. ceylon journal of science. 49(1): 49-59. rabl, d., gottsberger, b., brehm, g., hofhansl, f., fiedler, k., 2019. moth assemblages in costa rica rain forest mirror small-scale topographic heterogeneity. biotropica. ranwala, s.m.w., dilrukshi, i.a.d.n., wijesundera, d.s.a., attanayake, a.m.a.s., 2017. the first record on biodiversity of the natural arboretum of seethawaka wet zone botanic gardens, sri lanka. the sri lanka forester. 38: 25-45. sammani, a.m.p., dissanayaka, d.m.s.k., wijayaratne, l.k.w., morrison iii, w.r., 2020. effect of pheromone blend components, sex ratio, and population size on the mating of cadra cautella (lepidoptera: pyralidae). journal of insect science. 20(6): 1-7. sanyal, a.k., dey, p., uniyal, v.p., chandra, k., raha, a., 2017. geometridae stephens, 1829 from different altitudes in western himalayan protected areas of uttarakhand, india (lepidoptera: geometridae). shilap revista de lepidopterologia. 45(177): 143-163. schmidt, b.c., roland, j., 2006. moth diversity in a fragmented habitat: importance of functional groups and landscape scale in the boreal forest. annals of the entomological society of america. 99(6): 1110-1120. schulze, c.h., fiedler, k., 2003. hawkmoth diversity in northern borneo does not reflect the influence of anthropogenic habitat disturbance. ecotropica. 9: 99-102. sebua, c.m.d., nuňeza, o.m., 2020. species diversity of lepidoptera in western mindanao state university – experimental forest area, zamboanga city, philippines. entomology and applied science letters. 7(4): 33-43. gunathunga et al. /journal of tropical forestry and environment vol.12. no. 01 (2022) 10-23 23 singhamuni, s.a.a., hemachandra, k.s., warnasooriya, p.g.a.s., 2021. egg parasitoids of cabbage caterpillars in sri lanka: a search for biocontrol agents. the journal of agricultural sciences – sri lanka. 16(1): 174-181. sutrisno, h., 2010. the impact of human activities to dynamic of insect communities: a case study in gunung salak, west java. hayati journal of biosciences. 17(4): 161-166. trigunayat, m.m., trigunayat, k., 2021. on the diversity of moth fauna of keoladeo national park, bharatpur. international journal of recent scientific research. 12(1): 40515-40518. wagner, d.l., fox, r., salcido, d.m., dyer, l.a., 2021. a window to the world of global insect declines: moth biodiversity trends are complex and heterogenous. pnas. 118(2). wijerathna, h.m.p.a., shama, a.f., noyalin, m., wijeyamohan, s., 2021. a preliminary study on the moth diversity (lepidoptera) of university of vavuniya, pampaimadu, sri lanka. vavuniya university international research conference 2021. 65-70. wijesekara, a., wijesinghe, d.p., 2003. history of insect collection and a review of insect diversity in sri lanka. ceylon journal of science (bio. sci.). 31: 43-59. zurita, g., pe’er, g., bellocq, m.i., hansbauer, m.m., 2012. edge effects and their influence on habitat suitability calculations: a continuous approach applied to birds of the atlantic forest. journal of applied ecology. 49(2): 503-512. singh et al. /journal of tropical forestry and environment vol. 12, no. 01 (2022) 31-43 31 traditional agroforestry of angami nagas of nagaland state, indiaa quantitative assessment of socio-cultural values and agrobiodiversity akoijam basanta singh1*, robindra teron1, ajit kumar tamuli1 1department of life science and bioinformatics, assam university, diphu campus, diphu, karbi anglong 782 462, assam, india date received : july 2, 2022 date accepted : october 6, 2022 abstract nhalie (shifting cultivation) and teizie (home garden) are the major forms of traditional agroforestry practices of angami nagas in kohima district of nagaland. they are characterized by high socio-cultural significance and prevalence of high degree of agrobiodiversity. the present study aims to assess agrobiodiversity and socio-cultural values of nhalie agroforestry of angami nagas in kohima district of nagaland, india. this study collected primary data from 60 households across five angami villages by using methods of group discussion and participatory interview. teizie and nhalie had higher average cultural ecosystem service values of 7.5 and 7.1, respectively. in term of economic ecosystem services, nhalie cultivation was perceived to be an important agroforestry practice with social use value (suv) of 52.21. a total of 136 landraces of traditional crops belonging to 36 species were recorded. two scented rice landraces (kethselha and rüluoo) and one sticky landrace (nhalenya) were reported. high overall simpson’s diversity index value of 0.72 revealed high level of crop species diversity in nhalie agroforestry of angami nagas. rice was the most common crop with the highest genetic diversity (22 landraces) followed by pumpkin, squash, taro, cucumber and maize. nhalie agroforestry could serve as the major reservoir of traditional crop species and contribute to the conservation of these valuable traditional crop species on-farm. further, the existing agrobiodiversity managed with the traditional wisdom of angami nagas in nhalie agroforestry systems is required to be preserved and disseminated for sustainable use of bioresources. keywords: nhalie cultivation, cultural ecosystem services, landraces, conservation 1. introduction traditional agroforestry is a variant of conventional agroforestry ingeniously devised by indigenous people in different ecological regions of the world. these traditional farming systems have emerged over centuries of cultural and biological evolution and represent accumulated experiences of indigenous farmers interacting with the environment without access to external inputs, capital or modern scientific knowledge (chang, 1977; grigg, 1974; pandey et al., 2021). jhum (shifting cultivation) is one of the most ancient, complex, multifaceted and, until lately, ecologically stable form of agroforestry (sharma, 1976; darlong, 2004; pandey et al., 2021). in this system, multipurpose traditional tree species are managed along with diverse indigenous crop varieties (singh et al., 2014). though jhum is an ageold agricultural system, it is still prevalent in the north-eastern hill regions and some other humid and hilly regions of india. structural complexity, species diversity, productivity and socio-economic scopes of jhum system vary enormously in various locations. there has been no comprehensive understanding of the structure and function of this indigenous system of agriculture. there is a need for diagnosing the complexity of farmers’ production system to understand the way farmers maintain, preserve and manage agrobiodiversity over the years (pandey et al., 2021). terrace cultivation, jhum cultivation and home gardens are the various forms of traditional agricultural systems in nagaland. these systems are well adapted to hilly terrains of this state, and are characterized by the prevalence of high degree of agrobiodiversity (nakro, 2011). correspondence: basanta57@gmail.com issn 2235-9362 online ©2022 university of sri jayewardenepura 32 jhum cultivation is deeply ingrained in the culture, customs and beliefs of nagas, and 60% of the population of nagaland relies on agroforestry for livelihoods (gon, 2015; gon, 2019). traditional jhum cultivation involves a jhum cycle of 15-20 years of which one or two years for cultivation followed by a period of fallow regeneration for 13-18 years (rathore et al., 2010). the angami nagas subsist primarily by cultivating the hill slopes surrounding their village (changkija, 2014). alder-based jhum is one of the major forms of traditional agroforestry systems of the angami nagas (rathore et al., 2010; nakro, 2011). construction of terraces is not feasible in many parts of this mountainous state (neped and iirr, 1999). therefore, the replacement of jhum practices with permanent terrace cultivation is not possible in many places, and jhum system persists to be the major source of food and subsistence needs of poor marginalized farmers. majority of traditional varieties of crops are grown chiefly in jhum fields. underutilized indigenous crops are economically, socially and environmentally more compatible, and are nutri-rich and much adapted to marginal conditions (pandey et al., 2021). indigenous landraces of various crops harbour novel genes for future crop breeding programmes (patra et al., 2016). farmers grow indigenous landraces of various crops according to their preferences with respect to colour, taste, aroma and cooking quality. angami food system is supplemented with diverse major and minor dishes collected from farm and wild ecosystems (singh and teron, 2017). in recent times, agricultural practices have been intensified for increasing crop yields to meet the demand of increasing human population. such intensification makes significant changes in the traditional agricultural practices. for example, jhum cycle (traditionally 15-20 years) has been reduced to 4-7 years; folk varieties of crops have been gradually replaced with high yielding varieties (hyv); and traditional jhum systems gradually lose their resilience power. shorter jhum cycle cannot give sufficient time for fallow regeneration. these changes cause rapid deterioration of soil quality, further affecting crop yields and loss of valuable plant genetic resources (neped and iirr, 1999; nakro, 2011; changkija, 2014). nakro (2011) reported diversified forms of traditional agriculture practices and agrobiodiversity in nagaland. mezhü et al. (2017) studied the genetic diversity of locally cultivated taro from 11 districts of nagaland including 11 cultivars from kohima district. thirty indigenous crop species cultivated by konyak naga were reported from mon district of nagaland (pandey et al., 2021). twenty-nine upland rice landraces were reported from kohima district of nagaland (roy et al., 2014; toshimenla et al., 2016; vanlalsanga et al., 2019). some studies reported diversity of crop species and wild edible plants (wep) managed in angami homegardens (singh and teron, 2015; singh and teron, 2017). pandey et al. (2020) studied the socio-cultural and economic importance of jhum cultivation in mon district of nagaland. review of various reports revealed scant information on agrobiodiversity and cultural values of traditional agroforestry systems of angami nagas of nagaland. the present study aims to assess agrobiodiversity and socio-cultural values of nhalie agroforestry of angami nagas in kohima district of nagaland. this study would be helpful for policy makers to address the present issues of jhum cultivation in the state. further, information generated from this study will be of immense contribution to conservation of agrobiodiversity and commercial promotion of underutilized indigenous crops in the state. 2. materials and methods 2.1. the study area and the people nagaland represents one of the eight states in north-eastern region of india. the kohima district (25°11’n – 26°n and 93°20’e – 94°55’e) of the state with its headquarter at kohima is located at 1450 m above sea level covering a geographical area of 4041 sq km. the region is considered as the homeland of the angami naga, one of the 14 naga tribes of the state (basic facts nagaland, 2018). there are more than 60 angami villages in kohima, and each village consists of 60-900 houses (punyu, 2010). this district harbours a rich diversity of indigenous crops such as rice, maize, millets, taro, squash and cucurbits. angami nagas have a rich tradition of indigenously evolved strategies for biodiversity conservation (godbole and sarnaik, 2009). they practice animistic form of religion which includes belief on multiple deities. under the influence of missionary, majority of the angamis have embraced christianity; today their animistic religion remains confined to only a few angami groups. agriculture singh et al. /journal of tropical forestry and environment vol. 12, no. 01 (2022) 31-43 33 is the main occupation and rice is their staple food. wet terrace and jhum cultivation are the major forms of agricultural systems. figure 01. land use map of kohima district showing the study sites (blue circles) (source: nagaland gis and remote sensing centre planning and co-ordination department, government of nagaland) 2.2. collection of data the present study was conducted in five angami villages, namely rusoma, dihoma, mima, mitelephe and kigwema in kohima district of nagaland from 2019 to 2021 (figure 01). permission for field study and consents were obtained from the chairmen of village councils and key informants, respectively. selection of villages in this study was based on some important parameters including prevalence of jhum cultivation in the village, level of dependency of rural angamis on jhum and accessibility to study area (pandey et al., 2021). fifteen elderly knowledgeable farmers who had experiences of more than 10 years in jhum cultivation were selected from each of the five angami villages for group discussions on traditional knowledge of plant propagation, management of each plant species cultivated in agroforestry, food habit, socio-cultural and economic importance of various crops, yields, size of agricultural plots, traditional knowledge of post-harvest techniques, processing and storage of crops. a checklist of plants available in angami agroforestry fields was prepared through group discussions and personal observations in the field (vogl et al., 2004). free listing interviews of 30 elderly women were conducted to document uses and the cultural importance of weps (guest et al., 2006). 2.3. social research methods sixty landowners who had extensive knowledge about traditional land use systems, were interviewed. to assess the importance of provisional and cultural ecosystem services of traditional agroforestry systems, farmers were asked to rank the cultural, commercial and subsistence value of agroforestry systems on a scale of 1–10 by participatory interview (salmon, 2007). socio-cultural values comprised cultural, commercial and subsistence attributes and ranged from 1 (least important) to 10 (most important) (pietersen et al., 2018). the average score for each agroforestry system was calculated. farmers were asked to rank 33 woody plant species that provided the economic ecosystem services including crafting materials, food, medicine, construction materials, shadow and fencing trees, fodder, firewood, ornamental and reforestation species (de groot and van der meer, 2010). further, farmers were asked which agroforestry system that each product was collected from and if the product was used mainly for commercial or subsistence purposes to determine the social use value (suv) of the traditional 34 agroforestry systems (holzman, 2012). the suv was calculated based on the number of times a plant species for a specific use was collected from a certain agroforestry system, and as a percentage of the total number of all registered plant individuals perceived to be important for the economic ecosystem services (pietersen et al., 2018). a total of 113 species perceived to be important for the economic ecosystem services were registered. 𝑆𝑈𝑉 = ∑ 𝑛 𝑁 × 100 𝑆𝑝𝑒𝑐𝑖𝑒𝑠% = 𝑛 𝑁 × 100 where, n is the number of species used for one specific economic ecosystem service and n is the total number of species registered (113). 2.4.analysis of crop species diversity twelve households were selected from each of the five angami villages, and the analysis of crop species diversity was carried out on the respective household’s jhum field. a single household and its jhum field were considered as a sample for species diversity analysis. for the jhum field assessment, a square quadrant of 20m × 20m each was laid in the sampled household’s jhum field and accounted for vegetation of agricultural species (pandey et al., 2021). participatory approach was adopted to ensure that the sample plots could cover both perennial woody species and annual crop species in the jhum fields (pandey et al., 2021). plant species growing in the sample plots were enumerated, and the number of individuals of each species was recorded. crop species diversity was measured using the simpson’s diversity index (sdi) (simpson, 1949). crop diversity was calculated using the following formula: 𝐷 = 1 − ∑ 𝑛(𝑛 − 1) 𝑁(𝑁 − 1) where, n is the number of individuals of each species and n is the total number of individuals of all species. the crop diversification index was worked out based on household-level information of tribals (pandey et al., 2021). 3. results 3.1. angami agroforestry angami agroforestry system was categorised into four distinct forms based on the associated local management practices. they are (i) nhalie (jhum), (ii) teizie/ozhwe/avie (home garden), (iii) tekhu (terrace field) and (iv) luzhü (plantation of different fruit trees in combination with annual crops). each of these systems has its distinctive structure, functions and socio-cultural significance. these systems persist as means of basic economic and subsistence needs of the rural people. further, management of these systems reflects the inter dependency and cultural bonding among the rural angamis. 3.2. socio-cultural values of traditional agroforestry system this study evaluated the socio-cultural value for identity, commercial and subsistence of the major forms of angami agroforestry systems. the socio-cultural values ranged from 4 to 8.4 (table 01). mean assigned value of cultural ecosystem services indicates the relative importance of traditional agroforestry systems. results of this study revealed that nhalie and teizie had the highest commercial value of 7.6 each, whereas the lowest commercial value of 4 was found in tekhu. teizie had the highest subsistence value of 8.4 followed by tekhu (7.3), nhalie (6.6) and luzhü (4.7), whereas the highest cultural identity value (8.2) was found in tekhu. the highest average value of cultural ecosystem services was found in teizie (7.5) followed by nhalie (7.1), tekhu (6.5) and luzhü (5.4). therefore, teizie was perceived to be the most important agroforestry system. however, no agroforestry system can cope with all the needs of a farmer. as a result, farmers subsist on all forms of traditional agroforestry. this study documented 33 woody species from traditional agroforestry. results of this study revealed that nhalie and teizie could provide all the enumerated economic ecosystem services (table singh et al. /journal of tropical forestry and environment vol. 12, no. 01 (2022) 31-43 35 02). teizie had the highest suv (67.26), whereas the lowest suv was found in luzhü (20.32). farmers used the highest number of woody species belonging to different economic ecosystem services from teizie (76) followed by nhalie fields (59), tekhu fields (56) and luzhü (23). table 01. assigned values of cultural ecosystem services of angami agroforestry systems local management agroforestry systems cultural identity value commercial value subsistence value mean value nhalie slash and burn 7.1 7.6 6.6 7.1 teizie home garden 6.4 7.6 8.4 7.5 tekhu terrace field 8.2 4 7.3 6.5 luzhü plantation of fruit trees with combination of crops 5.5 5.8 4.7 5.4 table 02. potential economic ecosystem services of woody species in nhalie, teizie, tekhu and luzhü in kohima district of nagaland, india use categories nhalie teizie tekhu luzhü species % no. of species used species % no. of species used species % no of species used species % no. of species used crafting material 7.08 8 8.85 10 6.19 7 0.88 1 construction 8.85 10 10.62 12 7.08 8 0.88 1 food 7.08 8 14.16 16 8.85 10 6.19 7 firewood 14.16 16 17.70 20 12.39 14 5.31 6 fodder 1.77 2 1.77 2 1.77 2 0 0 medicine 3.54 4 4.42 5 5.31 6 4.42 5 ornamental 0.88 1 0.88 1 0.88 1 0.88 1 reforestation 7.08 8 6.19 7 0 0 0.88 1 shadow and fencing 1.77 2 2.65 3 1.77 2 0.88 1 total 52.21 59 67.26 76 45.13 51 20.32 23 figure 02. agrobiodiversity in jhum agroforestry of angami nagas (a) squash, (b) wax gourd, (c) ginger, (d) lablab beans, (e) bottle gourd, (f) allium chinense, (g) allium sativum, (h) allium chinense, (i) pumpkin, (j) taro, (k) sticky maize, (l) non-sticky maize 36 3.3.crop diversity this study aimed to evaluate agrobiodiversity in nhalie agroforestry and documented 36 indigenous crop species belonging to 28 genera under 12 families. traditional crop species cultivated in nhalie agroforestry were categorized into four crop types (pandey et al., 2019) (supplementary table 01). for examplefield crops (12 species), vegetables and tubers (16), spices and condiments (7) and fruits (2). cucurbitaceae represented the highest number of species (8) followed by leguminosae (7), poaceae (5), solanaceae (4), amaryllidaceae (3), lamiaceae and malvaceae (2 each) and asteraceae, araceae, brassicaceae, phyllanthaceae, moraceae (1 each). a total of 136 landraces belonging to 36 crop species were recorded. this study revealed high level of genetic diversity in diverse indigenous crop species such as rice, maize, pumpkin, cucumber, taro, squash, brinjal, cowpea, lablab beans, beans, bottle gourd and wax gourd (figure 02). rice represented the highest number of landraces (22), whereas sorghum sp. and sunflower had the least number of landrace (1 each) (figure 03). out of 22 upland indigenous rice landraces reported, nine landraces could not be found in the study area (supplementary table 01). farmers reported two scented rice landraces (kethselha and rüluoo) and one sticky landrace (nhalenya). traditionally nhalie rice is broadly classified into two groups based on the year of nhalie cultivation, namely as pelulha (cultivated in first year nhalie) and thekelha (cultivated in second year nhalie). twenty-one rice landraces were under pelulha, while one landrace was thekelha. the present study documented four species of pumpkin (cucurbita moschata, cucurbita maxima, cucurbita pepo and cucurbita ficifolia) of which cucurbita ficifolia was reported from kohima district of nagaland for the first time. figure 03. distribution of landraces of indigenous crop species cultivated in jhum agroforestry rice was the principal crop grown by all respondents in agroforestry fields followed by maize (figure 04). among field crops beans, lablab beans, soyabeans and cowpea were also grown by a good number of respondents, whereas sunflower was the least cultivated species (8%). further, among vegetable crops squash, pumpkin, taro, cucumber and tomato were the most frequently preferred vegetables. significant number of respondents reported the use of chillies, onion, garlic and ginger as spices and condiments. indian gooseberry was reported to be the most cultivated fruit tree. 22 3 2 3 1 7 9 8 2 1 8 3 6 8 3 2 12 21 2 2 2 0 5 10 15 20 25 n u m b e r o f la n d ra c e s crops singh et al. /journal of tropical forestry and environment vol. 12, no. 01 (2022) 31-43 37 figure 04. percentage of the most frequently cultivated traditional crop species in the study area figure 05. simpson’s diversity index value for the sample area 3.4.crop diversification index the present study revealed high diversity of crop species in nhalie agroforestry from the sampled area. maximum species diversity was observed among spices and condiments followed by cereals, vegetables and tubers (figure 05). fruit crops had the least species diversity index. farmers cultivate several indigenous and traditional crops chiefly in nhalie agroforestry for their culinary preference and socio-economic significance. overall sdi value was found to be 0.72 in the sample area. 3.5.wild harvested plants rural angamis collect plethora of wild edible species from nhalie fallow and wild habitats which are located at road sides, secondary forests and other natural forest areas for food, medicine and animal feed. wild plants contributed 61% of the total products used by angami nagas. figure 06 presents the extent of collection and usage of weps by the respondents from nhalie fallow and wild ecosystems closer to residential areas. all respondents reported the use of weps as foods. usage of weps as animal feeds was reported by 66% of respondents, whereas usage of medicine was found among 58% of respondents. some respondents (41%) used weps for other utilities, such as firewood and fencing. 100 96 16 13 16 25 33 58 30 8 66 75 90 61 58 11 41 75 83 60 5 0 20 40 60 80 100 120 r ic e m a iz e jo b ' te a r f o x ta il m il le t s o rg h u m s p . c o w p e a l a b la b b e a n s b e a n s s o y a b e a n s u n fl o w e r t a ro p u m p k in s q u a sh c u c u m b e r t o m a to w a x g o u rd b ri n ja l g a rl ic s g in g e r in d ia n g o o se b e rr y f ig f re q u e n c y p e rc e n ta g e crops 0.7 0.64 0.81 0.38 0.72 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 field crops vegetables and tubers spices and condiments fruits overall sdi s d i v a lu e s 38 figure 06. usage of wild edible plants in the study area 4. discussion 4.1. continuation of traditional agroforestry the angami nagas classify land into two types based on the nature of useland for cultivation (nhalie, tekhu, teizie and luzhü) and residential land (changkija, 2014). teizie which had the highest mean value of cultural ecosystem services (7.5) was perceived to be the most important agroforestry system compared to nhalie, tekhu and luzhü. higher social use value of 67.26 in teizie revealed the higher dependency of poor farmers on home gardens for their livelihood and food security. angami nagas maintain teizie closer to their houses (godbole, 1998) and manage economically important crops (maize and sugarcane), vegetable crops (cabbage, broccoli, mustard, taro, squash, brinjal, tomato and cucumber), horticultural crops (fruit trees), spices and other wild edible species of frequent use. teizie has significant role in providing food supplementation throughout the year. further, teizie provides major source of animal feeds and firewood. however, teizie has lesser cultural value of 6.4 than that of nhalie and tekhu. angamis have been practicing nhalie and tekhu for centuries (nakro, 2011). distinctive structure, functions and socio-economic significance of these traditional upland agricultural systems have been evolved, and angamis obtain their subsistence needs from these upland farming systems. angami nagas are well known for their skills in terrace constructions even on highly steep sides of mountains where sufficient amount of rain is received for irrigation (nakro, 2011). one study revealed that the age of terraces was as old as the age of village since these terraces had been constructed at the time of establishment of the village and subsequently nhalie land of the village was also established (nakro, 2011). higher cultural identity value of tekhu (8.2) and nhalie (7.1) revealed the cultural importance of these traditional upland agricultural systems in the life of rural angamis. prevalence of tekhu in angami villages mainly depends on the feasibility of terrace constructions in the huge mountain terrains and sufficient availability of water for irrigation (nakro, 2011), whereas nhalie is common to all nagas. for exampletekhu is rare in dihoma village which receives less amount of rainfall as compared to other villages. in those villages where tekhu is not possible, farmers hardly have alternative means of livelihood other than management of nhalie and teizie, and thus they mainly rely on nhalie and teizie for their subsistence needs. many studies reported the adverse effects of recent shortening of nhalie cycle to 4-7 years including soil erosion and degradation of soil quality which cause rapid decline in crop yields (choudhury and sundriyal, 2003; nakro, 2011; rajkhowa et al., 2017). initiatives from government of nagaland for the introduction of alternative settled farming to replace jhum cultivation were not successful to large extent (choudhury and sundriyal, 2003). this can be attributed to reluctance of many farmers to adopt such newly introduced agriculture because of its high cost of production, inexperience in new farming, failure to convince the reliability of new farming, lesser cultural significance and emphasis on monoculture or less crop diversity. at the present time, though jhum cultivation is widely discouraged due to its adverse ecological impact, this system persists 100 58 66 41 0 20 40 60 80 100 120 wild foods medicine animal feeds other utilities p e rc e n ta g e o f re sp o n d e n ts usage of wild edibles singh et al. /journal of tropical forestry and environment vol. 12, no. 01 (2022) 31-43 39 as a major source of subsistence for marginalized poor farmers. higher average value of cultural ecosystem services (7.1) and economic ecosystem services (suv = 52.21) in nhalie cultivation showed the intrinsic value of this system which was ingrained so deeply in the life of angamis. therefore, it would be difficult to eliminate this system from the life of angamis. one study reported the persistence of jhum cultivation in mon district of nagaland since it was part of the culture and tradition of indigenous people, a means of livelihood, and there was lacking of any worthwhile alternative (pandey et al., 2020) which was consistent with the results of this study. as a result, complete elimination of jhum cultivation from nagaland state without any provision of alternative source of livelihood for marginalized farmers may not be possible (rajkhowa et al., 2017). rather, farmers may be encouraged to introduce agroforestry in jhum fields and manage suitable local tree species that can rejuvenate soil fertility faster and prevent soil erosion, and thus transform jhum into a sustainable upland agricultural system which can continue to contribute its valuable services to achieve sustainable development goals. 4.2. agrobiodiversity the present study attempted to quantify the diversity of indigenous traditional crop species managed in nhalie agroforestry of angami nagas in kohima district of nagaland, india. similar studies on agrobiodiversity in jhum cultivation have been earlier reported by various workers (alam and mohiuddin, 2009; pradheep et al., 2014; pandey et al., 2019). forty crop species including 20 rice cultivars cultivated in jhum fields were reported from chittagong hill tracts in bangladesh (alam and mohiuddin, 2009). collection of 138 accessions of agri-horticultural crops belonging to 42 species from mon district of nagaland signified rich variability in major field crops, such as rice, maize and foxtail millet (pradheep et al., 2014). quantitative assessment of crop species diversity in shifting cultivation was carried out in six states of northeast india and reported 12 field crops, 25 vegetable crop and 22 crop species of fruit, condiments and spices (pandey et al., 2019). results of this study revealed that kohima district of nagaland had richer crop species (36) than that reported from other parts of northeastern regions of indiamon district of nagaland (30 species), churachandpur district of manipur (32), saiha in mizoram (30) and dhalai district of tripura (19) (pandey et al., 2019). one study documented 39 and 37 crop species from west garo hills district of meghalaya and upper subansiri district of arunachal pradesh, respectively (pandey et al., 2019). at the aggregate level, cereal and pulse crops in the sampled areas was observed to be more diverse and the mean diversification index value was found to be 0.63 on nhalie agroforestry land (fig. 5). species richness of vegetables and spices and condiments (23 species) recorded in this study was higher than that reported from mon district of nagaland (18 species) (pandey et al., 2021). fruit species richness (2 species) in this study was less than that of earlier similar studies (pandey et al., 2019; pandey et al., 2021). overall sdi value of 0.72 was less than that reported from mon district of nagaland (pandey et al., 2021). this discrepancy in the species richness in jhum cultivation landscapes in various parts of northeast india may be attributed to two reasons(i) cultivators’ varied preference factors including colour, palatability, aroma, flavour and socio-economic significance of crops and (ii) varied adaptability of crops to varied physical factors including soil type, altitude, temperature and availability of water in various jhum landscapes. rice forms the most common crop possessing higher genetic diversity with 22 landraces of which 21 landraces belong to non-sticky type which is preferred for daily consumption followed by maize, squash, pumpkin, taro and cucumber. sticky types of rice are used in preparation of rice biscuits and rice beer, and are also used in ceremonies or festivals (pandey et al., 2021). however, farmers grow these landraces in lesser quantity since they are poor yielding (nakro, 2011). in rusoma village scented black rice was reported to be used in making tea. in this study, two scented rice landraces (kethselha and rüluoo) were reported from kohima district, while two other types of scented rice (gam and thaling) were reported from mon district of nagaland (pradheep et al., 2014). both sticky and non-sticky rice consist of both scented and non-scented types of rice. this study reported two types of maizesticky (kemengashüko) and non-sticky (kemephroshüko). traditionally, konyak nagas roast mature kernels and pound them in traditional wooden mortar and pestle to fine powder which is either used for preparing soup/porridge or as an alternative to milk powder for preparing tea; the coarse granules are either cooked 40 and eaten as rice or used as pig feed (pandey et al., 2021). whereas, angami nagas use maize mainly as food and pig feeds. corms and leaves of taro are mostly used for the preparation of an ethnic food of angami known as tathu and are also used to cook with meat (singh and teron, 2017). leaves, petioles and corms of taro are cooked with local edible grasses for feeding the pigs (bapat, 2013). of four species of pumpkin recorded in this study, cucurbita ficifolia was used as pig feed but not as human food. a good number of weps constitute vital ingredients of different traditional dishes of angami food system (singh and teron, 2017). the extent of usage of weps shows that jhum fallow and secondary forests rich in weps will augment the diversity of available food resources of angami nagas. maintenance of biodiversity is key for the sustainable production of food and other agricultural products which will ensure food, nutritional and livelihood security for the tribals of northeast india (pandey et at., 2019). 4.3. agroforestry for food and livelihood security this study revealed higher diversity of traditional crop species in nhalie agroforestry. rural angamis hardly procured foods from other places since there was lack of market facilities and public transportation system in village areas. therefore, rural angamis mainly relied on agroforestry products and wild edibles for their food. there had been simple form of intervillage buying and selling and exchange of farm products. many poor rural people who do not get permanent vender seats in major markets in the town directly sell their farm products and other wild edible plants at the price of retailers at footpath in the town areas or at the side of highways. it had also been observed that farmers brought their farm products to town areas and sold at wholesale rate to the retailers. interestingly, agroforestry products are sold at the price higher than that of vegetables or fruits brought from outside the state. though the price of agroforestry products is higher, people prefer to buy these products for the obvious reasons of organic and palatability. further, firewood harvested from the thinning and pollarding of fallow trees in nhalie fields are sold for generating additional cash income. thus, selling of various agroforestry products and weps serves as an important means of earning cash income for improving the economy of poor farmers. 4.4. motives for maintenance of high agrobiodiversity of local landraces angami nagas avert the risk of crop failure by cultivating many economic species (in teizie) and diverse heirloom folk varieties of crops (in nhalie fields). this ensures yield in the long term, maximum returns with low input of technology and resources and promotes diverse options in diet (harwood, 1979). indigenous upland rice landraces cultivated in jhum agroforestry in nagaland are poor yielding (roy et al., 2014). however, these landraces hoard many valuable traits, such as good taste, flavour, aroma, cold tolerance and drought stress tolerance important for crop improvement programmes (tirkey et al., 2013). farmers prefer indigenous varieties over the improved ones, select elite materials to suit their needs and sustain pure varieties in their farming system (pradheep et al., 2014). further, no hyv suitable for rainfed jhum ecosystems is available. therefore, frequency of use of local seeds is significantly higher among the jhumias (shifting cultivators) (lalengzama, 2019). many indigenous and traditional crop species have socio-cultural significances. for examplesticky rice is used for brewing rice beer which is used in many rituals, celebration and festivals; hard and dried pericarp of bottle gourd is beautifully crafted to form traditional container/cup for storing rice beer, for carrying water and drinking water; cylinder made from dried pericarp of luffa cylindrica and pumpkin are used for storing seeds (changkija, 2014); fibre obtained from dried pericarp of luffa cylindrica is used for cleaning cooking and eating utensils. hence, despite introducing modern agriculture and growing pressure to discontinue cultivation of traditional varieties, farmers persist in growing their heirloom traditional varieties chiefly in nhalie fields to fulfil their socio-cultural needs. this may contribute to the conservation of these valuable traditional crop species on-farm. women play a major role in selection of seeds and conservation of germplasm of local cultivars. they involve in all farm related works including carrying farm products and weps to nearby market. rice grains are exposed to the sun by spreading them in thin layer on a large traditional bamboo mat before they are stored in traditional granary made of bamboo mat. panicles of foxtail millet, ears of maize and bulbs of garlics or spring onion, dried fruits of brinjal (often longitudinally cut into four splits), chilli and cucurbits are safely kept for next year’s sowing by hanging them on the veranda or on rafter inside the home near smoke kiln to singh et al. /journal of tropical forestry and environment vol. 12, no. 01 (2022) 31-43 41 ward off pests (pradheep et al., 2014). traditional knowledge of angami nagas for the management of biodiversity is required to be preserved in order to ensure the conservation of the valuable genetic resources of traditional crop species. 4.5. influence of modern crops on angami agroforestry mixed cropping is the pattern of cropping in angami agroforestry. many farmers perceived that such cropping patterns can enhance productivity. in recent times, there have been changes in traditional land use systems towards permanent farming like horticulture and rubber plantation, replacement of indigenous varieties with modern crops/hyv and homogenization of agricultural production systems (dikshit and dikshit, 2014). introduction of modern crops decreases agrobiodiversity in traditional agroforestry and alters the structure and functions of traditional agroforestry systems into monoculture which narrows down ecosystem services, and thus eroding valuable plant genetic resources from the farmers’ fields. 5. conclusions teizie and nhalie had higher average cultural ecosystem service values of 7.5 and 7.1, respectively. in term of economic ecosystem services, nhalie cultivation was perceived to be an important agroforestry practice with suv of 52.21. a total of 136 landraces of traditional crops belonging to 36 species were documented. two scented rice landraces (kethselha and rüluoo) and one sticky landrace (nhalenya) were reported. two types of maizesticky (kemengashüko) and non-sticky (kemephroshüko) were recorded. rice was the most common crop with higher genetic diversity (22 landraces) followed by pumpkin, squash, taro, maize and cucumber. angami food system was also complemented by good number of weps collected from nhalie fallow and wild ecosystems. high level of genetic diversity in traditional crop species could be the potential source of novel genes for future crop improvement programmes. though traditional crops have been gradually replaced with hyvs, farmers persist to grow their heirloom traditional varieties chiefly in nhalie fields for the obvious reasons of palatability and socio-cultural significances. this may contribute to the conservation of these valuable traditional crop species on-farm. as a result, nhalie agroforestry of angami nagas could serve as a major repository of indigenous crop species. indigenous traditional crop varieties recorded in this study can be further characterized in the future research for their use in crop breeding programmes. further, the traditional wisdom of angami nagas for the management of agrobiodiversity in nhalie agroforestry is required to be preserved and disseminated for sustainable use of bioresources. despite adverse ecological impact and wide discouragement of jhum cultivation, complete elimination of this practice from nagaland state without any provision of alternative source of livelihood for marginalized farmers may not be possible. farmers may be encouraged to introduce agroforestry and manage suitable local tree species in jhum fields for the transformation of jhum into a sustainable upland farming system. acknowledgement authors are grateful to informants of kohima district who shared their traditional knowledge of agroforestry practices and management of agrobiodiversity. we thank local guides for their assistance and hospitality during field study. special thanks to mr. kevikhrietuo ngukha, mr khovi ngukha, mr menosale kire, miss ashino and mrs banuo kire for their assistance during the field visits and sharing their traditional knowledge of agroforestry practices. references alam, m.k., and mohiuddin m. 2009. shifting cultivation (jhum) agrobiodiversity at stake: bangladesh situation. acta horticulturae, 806:709-716. bapat av. 2013. genetic diversity of taro (colocasia esculenta l.) in mon district, nagaland, needs attention for its conservation. current science, 105:1036. basic facts nagaland. 2018. directorate of information and public relations. government of nagaland, kohima, nagaland. https://ipr.nagaland.gov.in/basic-facts-of-nagaland. accessed 11 september 2020. 42 chang, j.h. 1977. tropical agriculture: crop diversity and crop yields. economic geography, 53:241– 254. changkija, s. 2014. biodiversity of nagaland. department of forest, ecology, environment and wildlife. government of india, kohima. 39-41. choudhury, d. and sundriyal, r.c. 2003. factors contributing to the marginalization of shifting cultivation in north-east india: micro-scale issues. outlook on agriculture 32(1):17–28. darlong, v.t. 2004. to jhum or not to jhum: policy perspectives on shifting cultivation. missing link (tml), society for environment & communication. de groot, r.s. and van der meer, p. 2010. quantifying and valuing ecosystem services provided by plantation forests. in: baauhus, j., van der meer, p. and kanninen, m. (eds.), ecosystem goods and services from plantation forests; earthscan: new york, ny, usa, pp. 16–42. dikshit, k.r. and dikshit, j. k. 2014. north-east india: land, people and economy, springer, dordrecht. godbole, a. 1998. angami homegardens. in rastogi, a., godbole, a. and shengji, p. (eds.), applied ethnobotany in natural resource managementtraditional, icimod, kathmandu, pp. 65-70. godbole, a. and sarnaik, j. 2009. biodiversity, cultural diversity and sustainable development in north east india. in: jha, a., jha, s. and munjal, s. (eds.), bio-cultural diversity and sustainable development in north east india: status, vision and challenges. readworthy publications (p). ltd., new delhi, pp. 139-157. gon. 2015. report of the task force nagaland executive summary: niti aayog, government of nagaland, office of the agriculture production commissioner nagaland, kohima. https://niti.gov.in/writereaddata/ files/nagaland_report_0.pdf. accessed 30 june 2022. gon. 2019. economic survey 2018-2019, government of nagaland, directorate of economics and statistics. https://statistics.nagaland.gov.in/statistics/category/25. accessed 30 june 2022. grigg, d.b. 1974. the agricultural systems of the world. an evolutionary approach. cambridge university press. guest, g., bunce, a. and jonhson, l. 2006. how many interviews are enough? an experiment with data saturation and variability. field methods. 18(1):59-82. harwood, r.r. 1979. small farm development– understanding and improving farming systems in the humid tropics. westview press, colorado, usa, pp. 160. holzman, d.c. 2012. accounting for nature’s benefits: the dollar value of ecosystem services. environmental health perspectives. 120:a152–a157. lalengzama, c. 2019. agrarian structure and transformation in mizoram, north east india. iosr journal of humanities and social science. 24:6–23. mezhii, t.l., changkija, s., pattanayak, a., chaturvedi, h.p., devi, s.v. and kole, p.r. 2017. genetic characterization of locally cultivated taro germplasm from eleven district of nagaland, india. international journal of current microbiology and applied sciences. 6(8):3338-3348. nakro, v. 2011. traditional agricultural practices and sustainable livelihood. a thematic report 2009. department of planning and coordination. kohima: government of nagaland, pp. 43-46. neped and iirr. 1999. building upon traditional agriculture in nagaland, india. nagaland. philippines: environment protection and economic development, nagaland, india and international institute of rural reconstruction, silang, cavite. pandey, d.k., adhiguru, p., devi, s.v., dobhal, s., dubey, s.k. and mehra, t.s. 2019. quantitative assessment of crop species diversity in shifting cultivation system of eastern himalaya. current science. 117(8):1354-1357. pandey, d.k., adhiguru, a., singh, b., singh, b. and john, a. 2021. is traditional agroforestry system of nagaland bountiful for indigenous and traditional crops species diversity? indian journal of traditional knowledge. 20(3):803-809. pandey, d.k., de, h.k., dubey, s.k., kumar, b., dobhal, s. and adhigurue, p. 2020. indigenous people’s attachment to shifting cultivation in the eastern himalayas, india: a cross-sectional evidence. forest policy and economics. 111(2020): 102046. singh et al. /journal of tropical forestry and environment vol. 12, no. 01 (2022) 31-43 43 pandey, h.p., pokhrel, n.p., luitel, d.r., acharya, k. and shah, k.k. 2021. diversity of agroforestry species and uses in two ecological regions: a case from central nepal. advances in agriculture. 2021. article id 1198341. https://doi.org/10.1155/2021/1198341 patra, b.c., ray, s., ngangkham, u. and mohapatra, t. 2016. rice. in: singh, m. and upadhyaya, h. (eds.), genetic and genomic resources for grain cereals improvement. elsevier science, pp. 180. pietersen, s., lópez-acosta, j.c., gomez-díaz, j.a. and lascurain-rangel, m. 2018. floristic diversity and cultural importance in agroforestry systems on small-scale farmer’s livelihoods in central veracruz, méxico. sustainability. 10:279. pradheep, k. and nayar, e.r. 2014. collecting crop genetic resources from mon, a remote district of nagaland. indian journal of plant genetic resources. 27:201-208. punyu, k. 2010. oral history of the angami nagas. phd thesis, north east hills university, shillong. rajkhowa, d. j., baishya, l. k., ray, s. k., sharma, p. r., barman, j. and ezung, n. k. 2017. challenges, scope, and opportunities of jhum rejuvenation in nagaland. in: prakash, n., roy, s.s., ansari, m.a., sharma, s.k., punitha, p., sailo, b. and singh, i.m. (eds.), jhum improvement for sustaining farm livelihood and natural resource conservation in north eastern hill region: vistas and frontiers. icar research complex for neh region, meghalaya, india, pp. 42-56. rathore, s.s., karunakaran, k. and prakash, b. 2010. alder based farming system a traditional practice in nagaland. indian journal of traditional knowledge. 9(4):677-680. roy, s., rathi, r.s., misra, a.k., bhatt, b.p. and bhandari, d.c. 2014. phenotypic characterization of indigenous rice (oryza sativa l.) germplasm collected from the state of nagaland, india. plant genetic resources. 12:58–66. salmon, a. (2007). walking the talk: how participatory interview methods can democratize research. qualitative health research. 17:982–993. sharma, t.c. 1976. the pre-historic background of shifting cultivation. proceedings of seminar on shifting cultivation in north east india. north east india council for social science research. simpson, e.h. 1949. measurement of diversity. nature. 163:688. singh, a.b. and teron, r. 2015. diversity of wild edible plants used by the angami-nagas in kohima district of nagaland, india. pleione. 9(2):311324. singh, a.b. and teron, r. 2017. ethnic food habits of the angami nagas of nagaland state, india. international food research journal. 24(3):1061-1066. singh, a.k., arunachalam, a., ngachan, s.v., mohapatra, k.p. and dagar, j.c. 2014. from shifting cultivation to integrating farming: experience of agroforestry development in the northeastern himalayan region. in: dagar, j.c. and singh, a.k. and arunachalam, a. (eds.), agroforestry systems in india: livelihood security & ecosystem services. springer, new delhi, pp. 57-86. tirkey, a., sarawgi, a.k. and subbarao, l.v. 2013. studies on genetic diversity in various qualitative and quantitative characters in rice germplasm. indian journal of plant genetic resources. 26(2):132–137. toshimenla, singh, j. and changkija, s. 2016. genetic divergence studies on upland rice grown in nagaland, india. indian journal of agricultural research. 50(6):555-560. vanlalsanga, s., singh, p. and singh, y.t. 2019. rice of northeast india harbor rich genetic diversity as measured by ssr markers and zn/fe content. bmc genetics. 20:79. vogl, c.r., vogl-lukasser, b. and puri, r.k. 2004. tools and methods for data collection in ethnobotanical studies of homegardens. field methods. 16(3):285-306. microsoft word subasinghe et al_jtfe subasinghe et al., /journal of tropical forestry and environment vol. 2, no. 02 (2012) 43-48 43 agarwood-type resin from gyrinops walla gaertn: a new discovery s.m.c.u.p. subasinghe* 1 , d.s. hettiarachchi 2 , e. rathnamalala 3 1 department of forestry and environmental sciences, university of sri jayewardenepura 2 wescorp agarwood, wescorp group, canning vale, western australia, australia 3 sadaharitha plantations limited, alfred place, colombo 03, sri lanka date received: 29-03-2012 date accepted: 21-06-2012 abstract agarwood is an expensive resinous product extracted from some members of aquilaria and gyrinops species of the family thymalaeaceae. agarwood essential oil is a highly valued perfumery product in modern cosmetics and traditional attar. agarwood extraction from the above species and product manufacturing are done in india and southeast asian countries. however, overharvesting, low natural regeneration, and legal restrictions at present, have limited the supply of this product. gyrinops walla is recorded in the wet zone of sri lanka, and it had been very rarely recorded in extreme southwest india. however, recent reports of the abundance of g. walla in india are hard to find. studies were not conducted in the past for g. walla on its ability of agarwood resin production and the quality of that resin. this study is the first to identify the agarwood resin formation and the quality of g. walla which can be used as a substitute for that of aquilaria and other species of gyrinops. resinous tissues were extracted from six g. walla trees for the present study from two different areas, i.e., labugama and yagirala of the wet zone of sri lanka. the resins were solvent extracted in the laboratory and the resin quality was tested using gas chromatography analysis. the results indicated an extreme similarity of the compounds of g. walla resin with that of commercially available agarwood resins. however, further studies should be conducted to identify g. walla distribution and formation of agarwood. key words: gyrinops walla, aquilaria, agarwood 1. introduction internationally, agarwood is widely known for its fragrant resinous wood. agarwood refers to species within four genera: gyrinops, aetoxylon, gongystylis and more commonly, aquilaria within the family thymalaeaceae. the value of the resin currently found in a small percentage of trees mainly harvested from certain species in the genus aquilaria. the process of the oleo-resin production is the tree’s response to injury of its first line of defence, formation of phloem callus tissue, is inhibited from forming over the injury (blanchette, 2003). the resin derived from the agarwood tree is highly sought after for religious, medical, ceremonial and domestic activities by asian buddhists and moslems. in addition to that, a large demand is seen for agarwood in southeast asia, middle east and united states as a perfumery agent. *correspondence: upuls@sjp.ac.lk tel: +94-112758421, fax: +94 112803470 issn 2235-9370 print / issn 2235-9362 online ©2012 university of sri jayewardenepura subasinghe et al., /journal of tropical forestry and environment vol. 2, no. 02 (2012) 43-48 44 certain species of aquilaria and gyrinops, the two important agar producing genera are normally distributed in at least 12 countries: bangladesh, bhutan, cambodia, india, indonesia, lao pdr, malaysia, myanmar, philippines, thailand, vietnam and papua new guinea (stevens, et al., 2003). however, g. walla has not been included into the agarwood producing species. aquilaria trees are native to asia from northern india to vietnam and indonesia (blanchette et al., 2005). however, none of the species of the aquilaria genus has been recorded in sri lanka. g. walla is the only member in sri lanka of the genus gyrinops. according to dassanayake and fosberg, (1981), outside the wet zone of sri lanka, g. walla had been recorded only in the extreme southwest of india, where it appeared to be very rare. therefore it can be assumed that, g. walla occurs only in sri lanka at present based on the lack of information on finding this species in india. g. walla is a medium tall tree which grows up to 15 m in height with straight, slender trunk with a small, rounded crown. the bark of this species is brownish-grey and it is thin, smooth and strongly fibrous. therefore its bark is used as a binding material by the villagers. twigs are slender and wiry, rather shining and chestnut-brown in colour when young. leaves are oblong and 3.0-9.0 cm x 1.2-5.0 cm with a short, rather abrupt, bluntish acumen up to 1 cm long. petiole is short and 1-6 mm in length. inflorescence is terminal or few flowered with umbel-like heads. pedicels are 3-4 mm and thinly pilose. flowers are yellowish-white and the size of the calyx tube is 4-10 mm which is narrow (dassanayake and fosberg, 1981). papua new guinea uses gyrinops, locally known as eaglewood instead of aquilaria as agarwood. eaglewood was first discovered and harvested for resin production in papua new guinea in about 1998. at that stage, information on the species was unknown. it was only in 2001 that taxonomic work was undertaken which determined the species as gyrinops ledermannii. this was the first official recording of this species being harvested for their resin wood. fragrant compounds of agarwood are known to be sesquiterpenoids and chromone derivatives, which are the main source of agarwood’s particular odour (takemoto et al., 2008). agarwood oils vary in their composition; some oils contain a large amount of sesquiterpene compounds and others contain principally benzylacetone (yang et al., 1989). in addition to that, okugawa et al. (2000) reported that six sesquiterpenoids, namely jinkoh-eremol, agarospirol, alpha and beta santalols, dehydrocostus lactone and costunolide, isolated from agarwood, inhibited acid-induced writhing in mice (takemoto et al., 2008). 2. methodology the objective of the present study was to identify the resin production ability of g. walla trees and to match the resin quality with that of commercially available authentic samples extracted from aquilaria species. 2.1. sampling six trees growing in two distinctive areas of the wet zone of sri lanka, i.e., labugama, of seethawaka ds division, colombo district and yagirala of walallawita ds division, kalutara district were used for the present study (table 1). 2.2. resin extraction the sample collection was done in november-december period of 2011. due to the unavailability of the records, the ages of the trees were not known. all six trees mentioned in table 1 had been naturally wounded sometime before the sample collection due to abrasions or wind-fallen branches. those areas were carefully observed and the decaying, black colour tissues were extracted using a pruning saw and a chisel. those samples were size reduced using a sharp edge cutter at the laboratory. those samples were air-dried and then put in a glass vial and the resin extraction was done using di-chloro methane. this subasinghe et al., /journal of tropical forestry and environment vol. 2, no. 02 (2012) 43-48 45 process was repeated up to three times. combined extract was then evaporated under negative pressure and sample was stored away from light until further analysis. table 1: location details and sizes of the six trees used for the study location tree no. dbh (cm) height (m) latitude longitude labugama yagirala 01 02 03 04 05 06 12.0 21.5 30.0 22.5 15.0 8.5 8.0 12.0 20.0 10.5 7.5 8.0 6 0 48 / 58.496 // 6 0 48 / 28.699 // 6 0 48 / 26.161 // 6 0 21 / 40.064 // 6 0 21 / 39.967 // 6 0 21 / 40.259 // 80 0 10 / 25.352 // 80 0 10 / 24.917 // 80 0 10 / 26.612 // 80 0 10 / 41.732 // 80 0 10 / 41.830 // 80 0 10 / 42.708 // 2.3. gas chromatography analysis weighed amount of the extract was dissolved in ethyl acetate to make a 10 mg ml -1 solution. this solution was then injected (1 µl) to the gas chromatography instrument (gc2010, shimadzu scientific, japan) using an auto sampler (aoc20i, shimadzu scientific, japan). separation was performed using a 5% phenyl-polysiloxane coated 30 m x 0.25 mm x 0.25 µm column (at-5, alltech, usa). injector chamber was kept at 250 0 c, whereas oven was programmed to increase from 120-250 0 c at the rate of 5 0 cmin -1 and held for 5 minutes. flame ionisation detector was held at 300 0 c. data were processed using the lab solutions software (shimadzu scientific, japan). standard alkane series of c8 to c40 (sigmaaldrich, usa) was used for the determination of retention indices. calibration curve was used to calculate the kovat’s retention indices. chromatograms and indices obtained from authentic agarwood samples were used for confirmation of published data. 3. results although, g. walla is a medium height tree which reaches up to 15 m (dassanayake and fosberg, 1981), the tree number 03 which was a free-grown tree at the edge of a homegarden of labugama has reached 20 m in height (table 1) at the time of sample collection. the heights of all other five trees were comparatively smaller. the resin contents of the samples varied from 4.4% to 10.9% with an average of 6.81%. however, since artificial resin induction had not been done and the naturally wounded areas of the selected trees were used for the present study, the pattern of the development of the tissues of the plants was not identified. the gas chromatography analysis revealed that the resin of g. walla found to contain several aroma principles commonly found in agarwood (table 2). all types of agarwood found to contain oxoagarospirol and jinkoh-eremol (yoneda et al., 1984). even though the presence of these compounds was lower in the analysed g. walla samples of the current study, they are important markers in identifying agarwood aroma (figure 1). sesquiterpenes of guaiane and eudesmane skeleton were also present in g. walla resin. these compounds were known to produce characteristic camphor like aroma with woody and floral notes (ishihara et al., 1991). apart from this, many fatty acids were also found to be common between the authentic and test samples. however, these resins were found to lack agarofuran, vetivae sequiterpenes and chromone derivatives, which are key components of the resin formed in aquilaria species (naf et al., 1993). subasinghe et al., /journal of tropical forestry and environment vol. 2, no. 02 (2012) 43-48 46 table 2: retention indices and the percentage areas of test and authentic samples compound retention index percentage area g. walla a. crassna* sample 1 sample 2 sample 3 sample 4 sample 5 sample 6 1 jinkho-eremol 1641 1643 0.38 0.49 0.78 0.78 0.46 0.57 2 selina--3,11-diene-9one 1689 1687 0.59 0.51 4.87 4.15 1.02 2.19 3 selina--3,11-diene14-al 1733 1735 7.82 7.22 5.14 4.11 4.99 3.93 4 9,11-eremophiladien -8-one 1741 1740 1.64 1.57 0.92 0.86 0.86 2.76 5 guaia-(10),11-dien15-ol 1766 1770 2.65 1.79 1.61 1.42 1.49 1.62 6 oxo-agarospirol 1818 1822 1.21 0.87 0.78 0.8 0.59 1.64 * source: wetwitayaklung et al. (2009) figure 1: chromatogram of the test sample 06. 4. discussion and conclusions the genera aquilaria and gyrinops are well known for the production of agarwood which is highly wanted for forest product of substantial economic value (eurlings and gravendeel, 2005). according to ng et al. (1997), out of 15 recorded species, nine species of aquilaria, i.e., a. beccariana, a. crassna, a. filaria, a. hirta, a. khasiana, a. malaccensis, a. microcarpa, a. rostrata, and a. sinensis produce agarwood. in addition, agarwood production has been recorded from gyrinops ledermanii and g. versteegii (compton and zich, 2002) although there are eight recorded species in the genus gyrinops. however, this is the first time of identifying the ability of g. walla for producing agarwood. however, more studies are required in this aspect to identify the potential of harvesting the resins from g. walla at commercial scale. a study conducted on agarwood oil by takemoto et al. in 2008 proved that the constituents of agarwood oil vary between trees. in their study they found that the agarwood oil tested in one sample had benzylacetone (47.1%) as the main volatile compound while alpha-aurjunene (62.5%) was the main compound of the second oil sample. subasinghe et al., /journal of tropical forestry and environment vol. 2, no. 02 (2012) 43-48 47 current method of gas chromatographic analysis could be used in identifying agarwood aroma principles from the trees of thymelaeaceae family. all six samples tested in the present study, have shown similar compounds according the gas chromatographic trace (fingerprint). majority of these compounds were unidentified due to the lack of references. in future, however, a gas chromatograph coupled with a mass spectrometer will be used to identify the remaining compounds. difference in the extraction method could play a significant role in the chemical properties of the resin rather than the biological origin. samples discussed in this study were extracted using a nonexhaustive solvent extraction method in comparison to a long hydro-distillation used in commercial agarwood production. in future, a sufficient sample will be collected and be subject to hydro-distillation to compare with an authentic agarwood oil samples. based on the results of the present study, it can be concluded that the current findings give a promising result for the first time on the resin formed in gyrinops walla and its capacity to produce agarwood type resins. references blanchette, r.a. 2003. deterioration in historic and archaeological woods from terrestrial sites. in koestler, r.j., koestler, v.r., charola, a.e., and nieto-fernandez, f.e. (eds), art, biology and conservation: biodeterioration of works of art. the metropolitan museum of art, new york, 328347pp. blanchette, r.a. and van beek, h.h. 2005. cultivated agarwood: patent no. 6,848,211 b2. united estate patent compton, j.g.s. and zich, f.a. 2002. gyrinops ledermannii (thymalaeaceae), being an agarwood producing species prompts call for further examination of taxonomic implications in the generic delimitation between aquilaria and gyrinops. flora malesiana bulletin 13(1): 61-66 dassanayake, m.d. and fosberg, f.r. 1981 flora of sri lanka: vol ii. 1981. oxford and ibh publishing company, new delhi eurlings, m.c.m. and gravendeel, b. 2005. trnl-trnf sequence data imply paraphyly of aquilaria and gyrinops (thymalaeaceae) and provide new perspectives for agarwood identification. plant systematics and evolution 254: 1-12 gunn, b., stevens, p., singadan, m., sunari, l. and chatterton, p. 2003. eglewood in papua new guinea. rmap working paper no 51 ishihara, m., tsuneya, t., shiga, m. and uneyama, k., 1991. three sesquiterpenes from agarwood. phytochemistry 30(2): 563-566\ naf, r., velluz, thommen, w., brauchli, r., sigwart, c. and gaudin, j-m., 1993. new compounds identified in agarwood (aquillaria aggalocha roxb.) flavour and fragrance journal, 8: 307-313 ng, l.t., chang, y.s. and kadir, a.a. (1997). a review on agar (gaharu) producing aquilaria species. journal of tropical forest products 2 (2): 272-285. okugawa, h., ueda, r., matsumoto, k., kawanishi, k. and kato, k. (2000). effects of sesquiterpenoids from “oriental incenses” on acetic acid-induced writhing and d2 and 5-ht2a receptors in rat brain. phytomedicine 7(5): 417-422. takemoto, h., ito, m., shiraki, t., yagura, t. and honda, g. 2008. sedative effects of vapour inhalation of agarwood oil and spikenard extract and identification of their active components. journal of natural medicine 62: 41-46. wetwitayaklung, p., thavanapong, n. and charoenteeraboon, j., 2009. chemical constituents and antimicrobial activity of essential oil and extracts of heartwood of aquilaria crassna obtained from water distillation and supercritical fluid carbon dioxide extraction. silpakorn university of science and technology journal. 3 (1): 25-33. subasinghe et al., /journal of tropical forestry and environment vol. 2, no. 02 (2012) 43-48 48 yang, j.s., wanf, y.l., su, y.l., he, d.h., zheng, q.t. and yang, j. 1989. studies on the chemical constituents of aquilaria sinensis (luor) gilg. iii. elucidation of the structure of the isobaimuxinol and isolation and identification of the constituents of lower boiling fraction of the volatile oil. yao xue xue bao 24(4): 264-268. yoneda, k., yamagata, etsuko, e., tsutomu, n., tsukasa, n, ichiro, k., toshio, y, hideo, m. and iwao, m. 1984. sesquiterpenoids in two different kinds of agarwood. phytochemistry 23(9): 2068-2069. borah et al. /journal of tropical forestry and environment vol. 9, no. 02 (2019) 21-35 __________________________________________ *correspondence: spsaikia@gmail.com tel: +91 9435096977 issn 2235-9370 print/issn 2235-9362 online © university of sri jayewardenepura 21 physiochemical studies in seedlings of teak (tectona grandis linn. f.) of north east india in relation to drought resistance for selection of improved germplasm n. borah1, p.k. borua2, s. roy3 and s.p. saikia1* 1medicinal aromatic and economic plants group, biological sciences and technology division, csirnorth east institute of science and technology, jorhat, india 2department of life sciences, dibrugarh university, dibrugarh, india 3division of genetics and molecular biology, csir-national botanical research institute uttar pradesh, india date received: 10-05-2018 date accepted: 23-12-2019 abstract the global climate change is occurring at an unpredictable rate, where periods of drought are predicted to be extremely severe. the drought tolerance in teak (tectona grandis linn. f.) accessions; collected from north east india was screened under water stress conditions created by reducing irrigation doses. parameters targeted for screening were vegetative growth, physiological parameters and chemical constituents of leaves. water stress treatment revealed that plant height, leaves number/plant, average leaf area, n, p, k, ca, cl and na content were significantly decreased by increasing the level of water stress conditions in all studied accessions. variations in the physiological parameters among different accessions may be due to different intensities of natural selection acting upon the traits in their natural habitat. the aim of the study was to determine source variation in tectona grandis linn. f. accessions collected from 41 locations of north east india and to identify the best sources to be utilised for reforestation and further genetic improvement work. in our study, three promising drought tolerant accessions were screened in a decreasing order of drought tolerance viz. gku-24, gku-37 and bnu-10 whereas; the drought stress had the most adverse effect on asm-124 and lut-45. keywords: drought, teak, physiochemical responses, forest, india 1. introduction water is the most limiting ecological resource for most tree and forest sites. as soil-water content declines, trees become more stressed and begin to react to resource availability changes. a point is reached when water is so inadequately available that tree tissues and processes are damaged. lack of water eventually leads to catastrophic biological failures and death. growing periods with litt le water can lead to decreased rates of diameter and height growth, poor resistance to other stresses, disruption of food production and distribution, and changes to the timing and rate of physiological processes, like fruit production and dormancy. more than eighty percent of the variation in tree growth is because of water supply. the effect is more prominent at early stage of growth. add to that, the excessive population and livestock pressure and the requirements of forest products for essential development generate a pressure on forest resources like fuel wood, fodder, timber, lumber, paper, etc. which in turn triggers a deforestation process. doi: https://doi.org/10.31357/jtfe.v9i2.4465 mailto:spsaikia@gmail.com 22 overexploitation of the forest's resources as compared to its incremental and regenerative capacities escalates the forest depletion and degradation process. excessive deforestation has not only local but also global environmental degradation ramifications. it can also affect sustainable socio-economic developmental processes in the developing countries as forests have been generating a lot of employment opportunities in the primary, secondary, and tertiary sectors and have been a source of subsistence to the poorest of the poor in the agricultural economies. furthermore, inhuman face of deforestation is characterised by the increasing stress on the poorer sections of the society and women, as they have been primarily involved in gathering fuel wood, fodder and water in the traditional village economies. the annual demand for industrial wood is about 28 million cubic meters against the production capacity of 12 million cubic meters. population pressure is always the underlying cause of overexploitation of the natural resources including forest stock. possibly, poverty, corruption, weak institutions, and wasteful consumption patterns also combine with the population pressure facilitating depletion and degradation of forest stock having enormous environmental degradation ramifications. therefore, it is very important to manage the forest in efficient way to meet the ecological need, human need and for better green world. amongst other various ways and means introduction of new germplasms with improved drought tolerance ability in degraded land will lessen the burden to some extent. understanding the physiology of drought tolerance at early stage of tree species like teak will be of great help to develop better stock for mass production. teak (tectona grandis linn. f.) (lamiaceae) is a tropical tree species. it is one of the world's premier hardwood tree species, highly famous for its quality, durability, dimensional stability, weightlessness and resistance to weathering. it is native to india, myanmar, thailand, and indonesia (verhaegen et al., 2010; vaishnaw et al., 2015). today, there is an urgent need for teak conservation measures, and this is especially important in the light of likely climatic changes in the years to come. due to population pressure and un favourable biotic factors, teak resources have considerably decreased both in extent as well as in density, quality and quantity over the natural range. establishing a comparative physiological mechanism that are active in plant system in different genotypes is utmost import ant to understand the mechanism of drought tolerance of plant species. teak is a widely adopted species and there are scanty of reports on its physiological studies especially in context to different abiotic stress viz. droughts. the aim of the present work is to screen the drought tolerance and drought sensitive teak plant based on various vegetative and physiological parameters as well as leaves nutrient analysis and to study how the vegetative, physiological and leaf nutrients differ between two contrasting teak plants (drought tolerance and sensitive) as well as the interaction of these factors regarding plant development, to identify the best sources to be utilised for reforestation and future genetic improvement work. 2. methodology 2.1 plant growth and water stress treatment t. grandis accessions were housed in an experimental greenhouse of csir-north east institute of science and technology, jorhat, assam, india which falls between 27.35o-26.30o n latitude and 93.45o94.30o e longitude and enjoys moderate type of climate. accessions of t. grandis were collected through survey from different regions of north east india, from parent plants chosen randomly from each population, which were about 100 m apart from each other. accession from each plant were collected and labeled to maintain their identities. the accessions were maintained in the nursery and 6-month old ownrooted uniformed accession were planted in plastic bags 20 cm diameter and 30 cm depth, each bag was filled with a constant weight (6 kg) of sand soil (in the ratio 1:1 by volume) and plants were pruned to single shoot. the sand soil was mainly used because it has low water holding capacity and thus suitable for drought stress studies. the upper portion of the green house was covered with green plastic shade, while the other parts remained open. two set of bags were arranged in factorial experiment in complete borah et al. /journal of tropical forestry and environment vol. 9, no. 02 (2019) 21-35 23 randomized design with three replications and each replicate was represented by nine plants. field capacity was calculated according to klute (1986) and the irrigation treatments were applied once in an interval of 7 days using normal tap water as follows: a. irrigation at 100% of field capacity (normal irrigation). b. irrigation at 75% of field capacity. c. irrigation at 50% of field capacity. d. irrigation at 25% of field capacity. the plants were kept at dehydration stress for a period of 6 months. the drought tolerant and sensitive plants were screened on the basis of repeated measurement of vegetative and physiological characteristics as well as analysing leaves chemical constituents. 2.2 vegetative characteristics measurements plant height, leaves number per accession and leaf area were determined to study the effect of water stress on different accessions of t. grandis. plant height was measured (cm) from the soil surface till the top of plant. the number of leaves/accession was recorded. leaf area was measured with a leaf area meter 211 (systronics) for five leaves chosen randomly from each plant and expressed as average leaf area per leaf. the leaf area was multiplied by the number of leaves occurring in the plant and was expressed as total leaf area per plant. 2.3 physiological characteristics measurements transpiration rate, stomatal conductance, net photosynthetic rate, relative water content, intrinsic water use efficiency, instantaneous water use efficiency, leaf area ratio, specific leaf area, root: shoot ratio and plant biomass were determined to identify the physiological adjustment of t. grandis l.f to water stress treatment. transpiration rate (mmol m-2 s-1), stomatal conductance (mol m-2 s-1) and net photosynthesis rate (µmolm-2s-1) were measured using a portable photosynthesis system tps-2 (pp systems). leaf relative water content (rwc) was calculated as (weatherley, 1950): rwc = [(fresh weight – dry weight) + (turgid weight – dry weight)] (1) turgid weight was determined by placing samples in distilled water and maintaining them at 5° c in darkness until they reached a constant weight. full turgor was typically reached after 12 hours. dry weight was obtained after placing the samples in an oven at 70° c for 48 hours. intrinsic water use efficiency (µmolmol-1) was determined as the ratio of net photosynthesis rate to stomatal conductance whereas instantaneous water use efficiency (µmolmmol-1) was determined as the ratio of net photosynthesis rate to transpiration (petite et al., 2000). leaf area ratio (cm2g-1 tdw) was calculated (radford, 1967) by dividing the total leaf area by plant (total) dry weight per plant and expressed in cm2g1 whereas specific leaf area (cm2 g-1ldw) was calculated (hunt, 1990) by dividing total leaf area by leaf dry weight per plant and the average value was expressed in cm2g-1. root-shoot ratio was calculated as the ratio of the dry weight of root to the dry weight of the shoot. plant biomass was determined as the biomass of the shoot and root dried to constant weight in oven at 70±2° c. 2.4 leaves chemical constituents measurements collected leaves samples were dried after washing several times with tap water, to constant weight at 70° c and then was digested in a mixture of sulphuric and perchloric acids according to piper (1950) and the following determinations was carried out as percent of dry weight. total nitrogen percentage (%) was determined using indophenols blue method according to novozamsky et al. (1974). phosphorus content was determined by spectrophotometry method according to temminghoff and houba (2004). 24 potassium, calcium and sodium were determined by using flame photometer according to brown and lilleland (1946). chloride was estimated by titration method with silver nitrate according to jackson (1958). free proline concentration was measured calorimetrically using ninhydrin reagent according to bates et al., 1973. total chlorophyll content in leaves was determined using dmso (dimethyl sulphoxide) according to hiscox and israelstam (1979). 2.5 statistical analysis statistical analysis was done according to the standard procedure (panse and shukhatme, 1967). results were taken to be reported as significant or non-significant based on least significant difference (lsd) test with significance level at p≤0.05. 3. results and discussion 3.1 accession source accession source of t. grandis are given in table 1. a clear cut distinction in the performance of the accessions was observed when grown under limited water conditions (irrigation at 25% of field capacity); the percentage of survival recorded was 100 in 5 out of the 41 accessions (table 2), while the rest showed very less survival percentage or failed to survive. thus these 5 accessions were taken for further study. 3.2 vegetative characterization of t. grandis in response to drought stress data presented in table 3 indicated that the plant height was significantly and gradually decreased with decreasing irrigation water at 100% to 75%, 50% and 25% from field capacity. irrigation at 25% from field capacity resulted in the lowest values in plant height with asm-124 followed by lut-45. increasing soil moisture stress by decreasing amount of available water of the soil led to a progressive significant reduction in plant height. the effect of stress may be attributed to the loss of turgor which affects the rate of cell expansion and ultimate cell size. loss of turgor is probably the most sensitive processes to water stress. consequently, water deficit decreased growth rate, stem elongation, leaf expansion and stomatal aperture. gku-24 and gku-37 recorded the highest significant values of plant height (20 and 13 cm respectively); on the other hand, asm-124 recorded the lowest values (5 cm) when irrigated at 25% from field capacity (table 3). thus, it can be summarised that plant height was decreased by increasing the level of water stress. leaves number/accession was significantly affected by water stress conditions in all studied teak accessions. the number of leaves decreased gradually with increasing water depletion up to 25 %. in general, in all studied accessions, which received normal (100%) or moderate irrigation (75%) produced the highest leaves number, while the lowest was produced when plants exposed to drought stresses (50% or 25%). however, under the same conditions of drought stresses, gku-24 seem to be more tolerant to severe drought stress, resulted in more leaves number in comparison to other studied accessions. the obtained results are in agreement with those of earlier finding where the leaves number was decreased by increasing the level of drought stress (gowda, 1998; abd el-samed, 1995, hassan, 1998 and shaheen et al., 2011). the average leaf area was significantly decreased with increasing drought stresses (table 3). the accessions which were irrigated with normal irrigation (100%) produced the highest leaf area, while the lowest was recorded when accessions were irrigated with 25% of the field capacity. however, lut-45 produced the lowest leaf area when exposed to severe drought stress (25%), while the highest leaf area was obtained with bnu-10 irrigated with normal irrigation (100%). drought stress reduced plant growth by affecting various physiological and biochemical processes (jaleel et al., 2008a,b; farooq et al., 2008); also, it affects both elongation and expansion growth (kusaka et al., 2005; shao et al. 2008). borah et al. /journal of tropical forestry and environment vol. 9, no. 02 (2019) 21-35 25 table 1: source detail of t. grandis and their geographical locations. accession code state locality latitude (n) longitud e (e) altitude (m) rain (mm) temp (°c) min max bnu-10 tripura baramura 23.83 91.65 904.00 2,800 8.5 33.0 bnu-11 tripura udaipur 23.31 91.31 24.68 2,100 12.0 35.0 bnu-14 tripura agartala 23.50 91.25 12.80 2,240 10.0 35.0 bnu-15 tripura kamalasagar 23.63 91.25 1,000.00 2,700 8.1 34.3 gku-20 nagaland tuli 26.44 94.65 1,325.00 2,330 9.3 28.0 gku-14 nagaland kohima 25.40 94.08 1,433.00 2,300 4.0 31.0 gku-16 nagaland namsa 26.78 94.77 897.64 1,644 5.3 25.5 gku-24 nagaland mokokchang 26.50 94.75 1,322.00 2,328 9.0 28.0 gku-37 nagaland wokha 26.09 94.25 1,313.69 2,293 9.0 25.0 chm-30 mizoram kolasib 24.13 92.40 660.54 2,860 7.0 32.0 chm-34 mizoram aizawl 23.36 93.00 1,132.00 3,000 11.0 30.0 chm-37 mizoram luntui 23.66 92.92 720.00 2,790 7.1 32.3 lut-39 meghalaya watrigithim 25.98 90.68 1,496.00 3,350 5.0 37.0 lut-40 meghalaya garo hills 25.30 90.13 870.00 2,600 7.0 30.0 lut-45 meghalaya west khasi hills 25.98 90.68 1,496.00 3,350 5.0 37.5 iag-16 manipur senapati 24.21 93.29 1,061.00 1,850 3.3 34.0 iag-52 manipur imphal 24.44 93.65 790.00 990 5.0 35.0 iag-37 manipur loktak 24.30 93.55 768.0 1,183 6.0 32.0 iag-64 manipur lamphelpet 24.44 93.65 790.00 2,027 3.2 34.5 puk-18 arunachal pradesh domukh 27.09 93.43 210.00 2,680 8.0 35.0 puk-10 arunachal pradesh itanagar 27.06 93.41 146.00 3,000 8.0 32.0 puk-87 arunachal pradesh naharlagun 27.00 93.42 200.00 2,688 8.0 32.0 puk-67 arunachal pradesh roing 28.05 95.89 300.00 2,800 5.0 29.0 puk-91 arunachal pradesh balijan 27.03 93.40 210.00 2,683 8.0 35.1 asm-34 assam golaghat 26.75 94.25 188.00 1,952 9.3 39.8 asm-105 assam dergaon 26.73 94.01 188.00 1,952 9.3 39.8 asm-124 assam karbi anglong 26.04 93.67 186.00 1,974 8.02 37.0 asm-16 assam sengeliati 26.45 97.30 126.70 1,872 8.8 38.9 asm-54 assam khakarpur 26.55 90.58 173.31 1,614 8.9 39.7 asm-29 assam titabor 26.64 94.20 192.00 1,993 9.0 38.2 asm-92 assam marigaon 26.15 92.20 189.00 1,973 10.0 38.3 asm-11 assam bongaigaon 26.15 90.34 53.00 3,500 12.9 31.7 asm-26 assam nagaon 26.45 92.41 69.00 1,745 10.0 35.0 asm-89 assam sonitpur 26.60 92.78 86.00 1,563 11.0 31.0 asm-6 assam dibrugarh 27.28 94.55 108.00 2,758 10.0 31.0 asm-69 assam dhubri 26.02 89.58 34.00 1,600 8.0 30.0 asm-84 assam lakhimpur 27.65 96.25 87.00 2,635 8.0 31.5 asm-46 assam sivasagar 27.00 94.36 97.00 2,504 7.0 29.0 asm-62 assam tezpur 26.37 92.47 79.00 1,600 7.0 36.0 asm-75 assam hajo 25.31 23.11 55.00 1,800 10.0 38.0 asm-51 assam jorhat 26.30 94.30 116.00 2,244 9.0 39.0 26 table 2: survival rate of t. grandis accession code survival (%) accession code survival (%) accession code survival (%) bnu-10 100.00 lut-45 100.00 asm-75 5.55 bnu-11 0.00 asm-124 100.00 asm-51 0.00 bnu-14 22.22 asm-16 0.00 iag-16 0.00 bnu-15 0.00 asm-54 0.00 iag-52 0.00 gku-20 10.00 asm-29 0.00 iag-37 14.44 gku-14 0.00 asm-92 10.88 iag-64 0.00 gku-16 0.00 asm-11 0.00 puk-18 0.00 gku-24 100.00 asm-26 0.00 puk-10 16.25 gku-37 100.00 asm-89 0.00 puk-87 0.00 chm-30 10.45 asm-6 0.00 puk-67 0.00 chm-34 0.00 asm-69 16.44 puk-91 0.00 chm-37 12.25 asm-84 0.00 asm-34 0.00 lut-39 0.00 asm-46 0.00 asm-105 0.00 lut-40 0.00 asm-62 0.00 3.3 physiological characterisation of t. grandis l.f. in response to drought stress transpiration is one of the major gas exchange related traits associated with plant growth and productivity. in tree species stomatal transpiration contributes more than 90% of total transpiration (taiz and zeiger, 2002). teak have been shown to precisely regulate transpiration rate via stomatal movements (bolhar-nordenkanpf, 1987) allowing this species to take advantage of favorable conditions through enhanced co2 uptake (fordyce et al., 1995), especially when exposed to significant seasonal fluctuations (greenwood et al., 2003). the results in table 4 showed that transpiration rate (e) was negatively affected by water stress and their decline under water stress was significantly higher in asm-124 (1.51 mmolm-2s1) followed by lut-45 and bnu-10 (1.63 and 1.68 mmolm-2s-1 respectively). like transpiration rate (e), stomatal conductance (gs) was also negatively affected by water stress, which decreased significantly with increasing water stress (table 4). gku-24 and gku-37 recorded the highest stomatal conductance (0.19 molm-2s-1) when exposed to severe drought stress (25%), while asm-124 recorded the lowest stomatal conductance (0.07 molm-2s-1) under similar condition. the results in table 4 also showed that like e and gs the net photosynthetic rate (pn) also decreased significantly with increasing drought treatments. the highest pn was observed in gku-24 (5.13 µmolm-2s-1) followed by gku-37 (2.0 µmolm-2s-1) when exposed to severe drought (25%) whereas the lowest pn was observed in asm-124 (1.09 µmolm-2s-1) followed by bnu-10 (1.11 µmolm-2s-1). reductions in the photosynthetic activity induced by drought were first triggered by stomatal closure, resulting in limitation of ambient co2 diffusion to the mesophyll and thus reduction of photosynthesis. leaf relative water content (rwc) decreased significantly with increasing drought (table 5). irrigation at 25% from field capacity resulted in the lowest values in rwc with asm-124 (39.68%) followed by lut-45. gku-37 and bnu-10 recorded the highest significant value of rwc (43.88 and 40.88%). drought stress-induced decrease in rwc has been reported in many previous studies (duan et al., 2005; elsheery and coa, 2008). data presented in table 5 indicated that the intrinsic water use efficiency and instantaneous water use efficiency decreased gradually with increasing water depletion up to 25%. however, at 25% from field capacity gku-24 recorded the highest intrinsic water use efficiency (160.77 µmolmol-1) and also showed highest instantaneous water use efficiency (3.17 µmolmmol-1) followed by gku-37 and in both, the lowest was recorded in asm-124. the higher is the value; the better is the efficiency of the plant to divert water for photosynthesis than transpiration. transpiration and photosynthesis are two major gas exchange parameters, which determine wue of plants. borah et al. /journal of tropical forestry and environment vol. 9, no. 02 (2019) 21-35 27 table 3: effect of water stress treatments on plant height, leaves numbers/accessions and leaves area. sd=standard deviation; cv=coefficient of variance; sem=standard error of mean. table 4: effect of water stress treatments on stomatal conductance (mol m-2 s-1), net photosynthetic rate (µmol m-2 s-1) and transpiration rate (mmol m-2 s-1). sd=standard deviation; cv=coefficient of variance; sem=standard error of mean. table 5: effect of water stress treatments on relative water content (%), intrinsic water use efficiency (µmol mol-1) and instantaneous water use efficiency (µmol mmol-1). sd=standard deviation; cv=coefficient of variance; sem=standard error of mean accession code plant height(cm) leaves numbers/accessions leaf area (cm2) irrigation treatments irrigation treatments irrigation treatments 100% 75% 50% 25% 100% 75% 50% 25% 100% 75% 50% 25% gku-37 20 18 13 13 15 12 10 9 4.7 3.9 3.3 3.0 gku-24 25 23 22 20 18 15 13 12 4.8 4.4 3.9 2.9 lut-45 13 13 10 9 13 9 9 8 4.3 3.1 3.1 2.5 bnu-10 15 13 12 12 10 11 8 7 5.0 3.7 3.1 2.6 asm-124 9 8 7 5 11 9 6 3 3.5 3.3 3.3 3.0 mean 16 15 13 12 13 11 9 8 4.5 3.6 3.3 2.8 sd 4.98 5.75 5.04 4.96 2.87 2.23 2.32 2.93 0.53 0.46 0.30 0.21 cv 0.31 0.38 0.39 0.41 0.22 0.20 0.26 0.36 0.12 0.12 0.10 0.07 sem 2.22 2.56 2.25 2.21 1.28 0.99 1.03 1.31 0.24 0.20 0.13 0.10 lsd value at 0.05=1.88 lsd value at 0.05=1.49 lsd value at 0.05=0.55 (ns) accession code stomatal conductance (mol m-2 s-1) net photosynthetic rate (µmol m-2 s-1) transpiration rate (mmol m-2 s-1) irrigation treatments irrigation treatments irrigation treatments 100% 75% 50% 25% 100% 75% 50% 25% 100% 75% 50% 25% gku-37 0.28 0.24 0.19 0.19 8.0 5.64 3.32 2.0 2.03 1.88 1.83 1.78 gku-24 0.46 0.25 0.19 0.19 11.23 8.62 6.34 5.13 1.89 1.86 1.86 1.93 lut-45 0.09 0.16 0.19 0.14 6.35 2.32 2.13 1.12 1.86 1.83 1.73 1.63 bnu-10 0.14 0.17 0.16 0.14 3.19 4.06 2.09 1.11 1.77 1.75 1.73 1.68 asm-124 0.07 0.11 0.07 0.07 4.16 2.06 1.02 1.09 1.80 1.53 1.51 1.51 mean 0.21 0.19 0.16 0.15 6.59 4.54 2.98 2.09 1.87 1.77 1.73 1.71 sd 0.15 0.04 0.04 0.04 2.86 2.41 1.83 1.56 0.09 0.13 0.12 0.14 cv 0.71 0.21 0.25 0.27 0.43 0.53 0.61 0.75 0.05 0.07 0.07 0.08 sem 0.07 0.02 0.02 0.02 1.27 1.07 0.82 0.70 0.04 0.06 0.05 0.06 lsd value at 0.05=0.09 lsd value at 0.05=1.35 lsd value at 0.05=0.09 accession code relative water content (%) intrinsic water use efficiency (µmol mol-1) instantaneous water use efficiency (µmol mmol-1) irrigation treatments irrigation treatments irrigation treatments 100% 75% 50% 25% 100% 75% 50% 25% 100% 75% 50% 25% gku-37 70.34 67.75 51.17 43.88 358.10 116.54 115.94 114.92 8.17 5.26 3.76 2.90 gku-24 69.14 60.53 48.65 40.10 363.48 199.00 163.41 160.77 10.46 6.91 3.85 3.17 2.96 ut-45 67.74 59.33 47.25 39.68 287.83 97.80 89.30 65.88 7.57 4.58 3.66 2.88 bnu-10 66.54 57.93 46.05 40.88 281.48 52.96 52.09 51.58 7.44 4.21 3.65 2.01 asm-124 64.94 56.53 44.65 39.68 276.25 40.23 38.22 34.89 7.21 3.88 3.18 1.96 mean 61.74 60.41 47.55 40.84 313.42 101.31 91.79 85.61 8.17 4.97 3.62 2.58 sd 1.90 3.90 2.24 1.58 38.88 56.31 45.09 46.10 1.19 1.07 0.23 0.05 cv 0.03 0.06 0.05 0.04 0.12 0.55 0.50 0.54 0.15 0.21 0.06 0.19 sem 0.85 1.74 1.00 0.71 17.36 25.14 20.13 20.58 0.53 0.48 0.10 0.22 lsd value at 0.05=1.97 lsd value at 0.05=19.59 lsd value at 0.05=0.82 28 the water deficit did not significantly affect the leaf area ratio (lar), however, specific leaf area (sla) increased significantly in plants submitted to decreasing irrigation water at 25% in comparison to 100% and those under 75% and 50% (table 6). gku-24 recorded the highest lar and sla when subjected to irrigated treatment under all conditions. the root: shoot ratio did not differ significantly between treatments. gku-24 recorded the highest root: shoot ratio when subjected to irrigated treatment under all conditions (table 6). data presented in table 7 indicated that biomass partitioning to leaves, shoot and root decreased gradually with increasing water depletion up to 25%. gku-24 recorded the highest biomass partitioning to leaves, root and shoot when subjected to decreasing irrigated water at 25% (16.4%, 35.0% and 49.2% respectively). 3.4 chemical characterisation of t. grandis l.f. in response to drought stress table 8 showed that an appreciable significant reduction in leaf n% due to increasing drought stress. the lowest nitrogen percentage was obtained at irrigation with 25% from field capacity in asm124 (1.78%), while the highest was obtained with gku-24 (2.20%). these results are in harmony with that reported by moustafa (2002). the nitrogen status of a plant has a significant influence over its water relation, as nitrogen and water often interact. when the soil faces a prolonged period of drought, nitrogen mobility is severely restricted by the dehydrated soil. thus, when a plant faces water deficit, nitrogen deficiency occurs (damatta et al., 2002), which rapidly inhibits plant growth. according to bänziger et al. (2000), about 50% of all n in the leaf is directly involved in photosynthesis as either enzymes or chlorophyll. thus, if the n supply is insufficient, photosynthesis is decreased by reducing the leaf area and photosynthesis rate as well as accelerating leaf senescence. the phosphorus content in leaves gradually decreased by decreasing water depletion from 100 to 25% from field capacity (table 8). table 6: effect of water stress treatments on leaf area ratio (cm2g-1 tdw), specific leaf area (cm2g-1 ldw) and root: shoot ratio. table 6: effect of water stress treatments on leaf area ratio (cm2 g-1 tdw), specific leaf area (cm2 g-1 ldw) and root:shoot ratio. accession code leaf area ratio (cm2g-1 tdw*) specific leaf area (cm2g-1 ldw**) root: shoot ratio irrigation treatments irrigation treatments irrigation treatments 100% 75% 100% 25% 100% 75% 50% 25% 100% 75% 50% 25% gku-37 80.30 86.30 74.83 82.73 284.16 317.30 272.91 451.28 0.72 0.64 0.60 0.65 gku-24 84.39 90.69 79.22 87.12 307.30 340.44 384.83 563.20 0.85 0.77 0.73 0.78 lut-45 75.93 82.23 70.76 78.66 282.91 316.05 360.44 539.11 0.70 0.62 0.58 0.63 bnu-10 82.93 89.23 77.76 85.66 251.28 284.42 328.81 507.18 0.79 0.71 0.67 0.72 asm-124 72.11 78.41 66.94 74.84 267.83 300.97 345.36 523.73 0.68 0.60 0.56 0.61 mean 79.13 85.38 73.90 81.80 278.70 311.84 338.47 516.90 0.75 0.67 0.63 0.68 sd 4.54 2.24 4.52 4.52 18.63 18.63 37.60 37.64 0.06 0.06 0.06 0.06 cv 0.06 0.03 0.06 0.05 0.07 0.06 0.11 0.07 0.08 0.09 0.09 0.09 sem 2.03 1.00 2.01 2.01 16.80 8.32 16.78 16.80 0.02 0.02 0.02 0.02 lsd value at 0.05=0.09 lsd value at 0.05=31.36 lsd value at 0.05=0.0 (ns) tdw-total dry matter weight, **ldw-leaf dry matter weight sd=standard deviation; cv=coefficient of variance; sem=standard error of mean borah et al. /journal of tropical forestry and environment vol. 9, no. 02 (2019) 21-35 29 table 7: effect of water stress treatments on biomass partitioning to shoot (%), biomass partitioning to root (%) and biomass partitioning to leaves (%). sd = standard deviation; cv = coefficient of variance; sem = standard error of mean table 8: effect of water stress treatments on leaves nitrogen percentage, leaves phosphorus percentage and leaves potassium percentage. sd = standard deviation; cv = coefficient of variance; sem = standard error of mean gku-24 seemed to have more p content compared to the other accessions at irrigation with 25% from field capacity. the obtained results were in agreement with those obtained by moustafa (2002) who concluded that the leaf p content increased as amount of applied water was increased in olive trees. a good supply of water is required for phosphate availability and absorption by plants. phosphate ions move through soils primarily through diffusion and if the water content in the soil decreases, the radii of waterfilled pores decrease, tortuosity increases and p mobility decreases (faye et al., 2006). drought causes a reduction in p absorption and transport in plants. a decrease in available p forms and increase in occluded p in the soil reduces p uptake and consequently induces lower foliar p content (sardans and peñuela, 2004). data presented in table 8 also indicated that potassium content in leaves was gradually decreased by decreasing water depletion from 100% to 25% from field capacity. in this regard, asm-124 produced lower k (0.70%) content compared to the other accessions when irrigated at 25% from field capacity. these findings are generally in line with previous reports that the leaves of olive contained a lower content of k when these plants are grown under severe water stress (gowda, 1998; hassan, 1998). water conditions in plants influence the k+ accumulation in leaves and interact with k+ nutritional status in some plant species (restrepo-diaz et al., 2008). the stomatal opening mechanism is governed by the k+ concentration (mengel and kirkby, 2001; larcher, 2006; taiz and zeiger, 2006; mengel, 2007). the accession code biomass partitioning to shoot (%) biomass partitioning to root (%) biomass partitioning to leaves (%) irrigation treatments irrigation treatments irrigation treatments 100% 75% 50% 25% 100% 75% 50% 25% 100% 75% 50% 25% gku-37 52.9 49.9 46.6 43.2 33.2 29.6 28.7 28.6 26.4 24.0 20.6 13.1 gku-24 58.9 55.9 52.6 49.2 33.0 36.0 35.1 35.0 29.7 27.3 23.9 16.4 lut-45 50.4 47.4 44.1 40.7 26.2 22.6 21.7 21.6 28.2 25.8 22.4 14.9 bnu-10 56.0 53.0 49.7 46.3 33.0 29.4 28.5 28.4 24.3 21.9 18.5 11.0 asm-124 57.8 54.8 51.5 48.1 34.0 30.4 29.8 29.4 15.9 13.5 10.1 4.6 mean 55.2 52.2 48.9 45.5 31.9 29.6 28.8 28.6 25.0 22.5 19.1 12.0 sd 3.14 3.14 3.14 3.14 2.86 4.26 4.27 4.26 4.82 4.84 4.85 4.12 cv 0.05 0.06 0.06 0.06 0.09 0.14 0.14 0.15 0.19 0.21 0.25 0.34 sem 1.40 1.40 1.40 1.40 1.77 1.90 1.91 1.90 2.15 2.16 2.16 1.84 lsd value at 0.05=0.0 (ns) lsd value at 0.05=2.01 lsd value at 0.05=0.61 accession code leaf n% leaf p% leaf k% irrigation treatments irrigation treatments irrigation treatments 100% 75% 50% 25% 100% 75% 50% 25% 100% 75% 50% 25% gku-37 2.30 2.15 2.10 2.05 0.37 0.30 0.30 0.26 1.10 1.00 0.93 0.92 gku-24 2.16 2.13 2.13 2.20 0.42 0.32 0.30 0.30 1.12 1.05 0.93 0.90 lut-45 2.13 2.10 2.00 1.90 0.27 0.27 0.20 0.20 0.93 0.82 0.75 0.73 bnu-10 2.04 2.02 2.00 1.95 0.35 0.35 0.34 0.25 0.98 0.90 0.75 0.73 asm-124 2.07 1.80 1.78 1.78 0.40 0.33 0.25 0.15 0.77 0.70 0.73 0.70 mean 2.14 2.04 2.00 1.97 0.36 0.31 0.28 0.23 0.98 0.91 0.82 0.80 sd 0.09 0.13 0.12 0.14 0.05 0.03 0.05 0.05 0.13 0.13 0.09 0.09 cv 0.04 0.06 0.06 0.07 0.14 0.10 0.18 0.22 0.13 0.14 0.11 0.11 sem 0.04 0.06 0.05 0.06 0.02 0.01 0.02 0.02 0.06 0.06 0.04 0.04 lsd value at 0.05=0.09 lsd value at 0.05=0.05 lsd value at 0.05=0.05 30 opening and closure of k+ channels are of particular importance to guard cells and this action mechanism is controlled by the reception of red light, which induces stomatal opening (mengel, 2007). under mild water stress, plants tend to reduce the stomata aperture and when water stress becomes severe, the stomata generally close (larcher, 2006). the effect of irrigation treatments on leaf ca content was significant as shown in table 9. results indicated that leaf ca content decreased by increasing drought stress. gku-24 recorded the highest significant value (0.20%) of leaf ca content, while asm-124 recorded the lowest significant value (0.11%) when irrigated at 25% from field capacity. these findings are in agreement with those obtained by moustafa (2002) and nomir (1994) where they concluded that leaf ca content was increased as amount of applied water was increased. analyzing the long-term effects of drought in a mediterranean evergreen (quercus ilex) forest, sardans et al. (2008) concluded that drought tended to decrease ca concentrations in the aboveground biomass and this effect was attributed to the reduction in transpiration flux. the na content in leaves gradually decreased by decreasing water depletion from 100% to 25% from field capacity (table 9). table 9: effect of water stress treatments on leaves sodium percentage, leaves chloride percentage and leaves calcium percentage. sd=standard deviation; cv=coefficient of variance; sem=standard error of mean however, the lowest na content (0.05%) was produced when asm-124 was exposed to severe drought stress (25%), while the highest (0.22%) when gku-37 was exposed to moderate drought stress (75%) in comparison to the other accessions under the same drought conditions. these results go in parallel with those obtained by nomir (1994) who illustrated that the decrease in soil moisture level decreased na content in persimmon leaves. the cl content in leaves gradually decreased by decreasing water depletion from 100 to 25 % from field capacity (table 9). however, the highest cl content (0.31%) was found when gku-24 was exposed to moderate drought stress (75%), while the lowest (0.13%) when lut-45 was exposed to 25% drought in comparison to the other accessions under the same drought conditions. these results were found to be in harmony with nomir (1994) who illustrated that the reduction in soil moisture level caused decrease in concentrations of cl content in persimmon leaves. chloride ion is involved in the photolysis of water by photosystem. it is required for cell division in both leaves and roots, plays an important role in stomatal movement and has important functions in osmoregulation and the water relation. data presented in table 10 indicated that proline accumulation in teak plants increased gradually with increasing the level of drought stress up to 25% in case of gku-24 and gku-37. the highest proline accumulation was obtained with gku-24 when subject under severe drought stress condition (25%) in comparison to normal irrigation and also to other drought stresses (50% and 75%). under accession code leaf na percentage leaf cl percentage leaf ca percentage irrigation treatments irrigation treatments irrigation treatments 100% 75% 50% 25% 100% 75% 50% 25% 100% 75% 50% 25% gku-37 0.22 0.22 0.20 0.14 0.35 0.22 0.25 0.20 0.30 0.25 0.23 0.20 gku-24 0.30 0.20 0.20 0.20 0.52 0.31 0.25 0.25 0.30 0.26 0.25 0.20 lut-45 0.23 0.15 0.14 0.13 0.23 0.17 0.13 0.13 0.24 0.20 0.18 0.12 bnu-10 0.25 0.17 0.17 0.13 0.30 0.23 0.22 0.20 0.25 0.23 0.20 0.17 asm-124 0.20 0.12 0.10 0.05 0.34 0.30 0.25 0.25 0.23 0.20 0.16 0.11 mean 0.24 0.17 0.16 0.13 0.34 0.24 0.22 0.20 0.26 0.23 0.20 0.16 sd 0.09 0.03 0.04 0.05 0.15 0.05 0.05 0.04 0.03 0.02 0.10 0.03 cv 0.56 0.17 0.25 0.38 0.57 0.21 0.23 0.20 0.11 0.08 0.50 0.19 sem 0.04 0.01 0.07 0.02 0.06 0.02 0.02 0.02 0.01 0.01 0.04 0.01 lsd value at 0.05=0.05 lsd value at 0.05=0.09 lsd value at 0.05=0.01 borah et al. /journal of tropical forestry and environment vol. 9, no. 02 (2019) 21-35 31 drought conditions, the accumulations of proline seemed to be associated with drought tolerance in many plant species (liu et al., 2011). proline accumulation may play a role in minimising the damage caused by dehydration (mohammadkhani and heidari, 2008). proline is an amino acid and known to act as an osmolyte, protecting the plasma membrane integrity (mansour, 1998), as a sink of energy or reducing power (verbruggen et al., 1996), as a scavenger of ros and their derivatives (hong et al., 2000; bashir et al., 2007) and as a source for carbon and nitrogen (peng et al., 1996), and thereby helping the plants to tolerate stress effects (manivannan et al., 2007). the results in table 10 also showed that chlorophyll content was affected by drought conditions. gku-24 recorded the highest significant value (0.70), while lut-45 and asm-124 recorded the lowest values (0.57 and 0.58 respectively) under severe drought stress condition (25%). similar results are in agreement with those obtained by liu et al. 2011; ghaderi and siosemardeh 2011; dias and bruggemann 2010; who found that chlorophyll was decreased with increasing water stress. the decrease in chlorophyll content has been considered to be a typical symptom of oxidative stress and may be the result of pigment photo-oxidation, chlorophyll degradation and/or chlorophyll synthesis deficiency (smirnoff, 1993). munne-bosch and alegre 2000; galmes et al. 2007; elsheery and cao 2008 explained this phenomenon as a photoprotection mechanism through reducing light absorbance by decreasing pigments content. table 10: effect of drought treatments on leaf proline (mg/g fresh weight) content and total chlorophyll content. accession code leaf proline (mg/g fresh weight) content total chlorophyll content irrigation treatment irrigation treatments 100% 75% 50% 25% 100% 75% 50% 25% gku-37 0.015 0.016 0.020 0.026 0.67 0.67 0.65 0.64 gku-24 0.016 0.023 0.024 0.033 0.75 0.71 0.71 0.70 lut-45 0.014 0.016 0.017 0.018 0.70 0.64 0.60 0.58 bnu-10 0.012 0.014 0.017 0.021 0.68 0.66 0.65 0.57 asm-124 0.012 0.015 0.018 0.023 0.66 0.66 0.61 0.60 mean 0.013 0.016 0.019 0.024 0.69 0.67 0.64 0.62 sd 0.003 0.003 0.002 0.007 0.03 0.02 0.04 0.05 cv 0.143 0.143 0.105 0.318 0.04 0.03 0.06 0.08 sem 0.001 0.001 0.001 0.004 0.01 0.01 0.02 0.02 lsd value at 0.05=0.01 lsd value at 0.05=0.03 sd=standard deviation; cv=coefficient of variance; sem=standard error of mean 4. conclusion limited availability of water is the major contributor to the forest decline and thus has significant effect on global forest cover (bigler et al., 2006; van mantgem et al., 2009; allen et al., 2010). however, like other crop plant species, tree species also developed strategies to cope with limited water supply. understanding these strategies including physiological and biochemical responses is vital to meet the challenges imposed by the global climate change phenomena including drought. decreasing the irrigation water, decreased the plant height, leaves number/accessions, leaf area, leaf content of n, p, k, ca, na and cl. accumulation of proline was also significantly affected by drought stress condition, which increased with increasing water deficit. similarly, the transpiration rate, stomatal conductance, net photosynthetic rate, relative water content, intrinsic and instantaneous water use efficiency, plant biomass and chlorophyll content were also significantly affected by drought stress condition. water deficit did not significantly affect the leaf area ratio however, the specific leaf area increased significantly in plants submitted to decreasing irrigation water. root: shoot ratio also did not differ significantly due to water deficit. gku-24, gku-37 and bnu-10 were found to be more tolerant to drought stress compared to the 32 other studied accessions. asm-124 and lut-45 showed more sensitivity towards drought and affected mostly by drought and the vegetative, physiological and chemical characteristics of accessions were found to be lower as compared to the other accessions. gku-24 was found to be the highest tolerance against drought followed by gku-37 and bnu-10. these sources can safely be used for large-scale reforestation programmes in the region. germplasm used in afforestation programmes in india and other countries, generally utilizes only locally available material. thus opportunities for using materials with high drought tolerance potential or with more desirable characteristics might have been missed. this work will facilitate selection of promising sources for multi-location evaluation and will also hasten the process of utilisation of germplasm. it further gives a direction to the effect and practice studies for genetic improvement of this species. acknowledgment the authors are grateful to the director, csir-north east institute of science and technology, jorhat, assam, india for his permission to publish the work. sps is thankful to department of biotechnology (dbt), government of india for financial support. s.p.s. thanks the anonymous reviewers for their insightful suggestions and critical reviews. references abd el-samed, g.a., 1995. effect of irrigation regimes on growth, yield and water use of olive trees. ph.d. thesis, fac. agric., fayoum, cairo univ., egypt. allen, c.d., macalady, a.k., chenchouni, h., bachelet, d., mcdowell, n., vennetier, m., kitzberger, t., rigling, a., breshears, d.d. and hogg, e.t., 2010. a global overview of drought and heatinduced tree mortality reveals emerging climate change risks for forests. for ecol manag, 259(4): 660-684. bänziger, m., edmeades, g.o., beck, d. and bellon, m., 2000. breeding for drought and nitrogen stress tolerance in maize: from theory to practice. cimmyt, mexico, d.f., 68. bashir, f., mahmooduzzafar siddiqi t.o. iqb and al, m., 2007. the antioxidative response system in soybean plants exposed to deltamethrin, a synthetic pyrethroid insecticide. environmental pollution, 147:94-100. bates, l.s., waldren, r.p. and teare, i.d., 1973. rapid determination of free proline for water-stress studies. plant and soil, 939:205-207. bigler, c., bräker, o.u., bugmann, h., dobbertin, m. and rigling, a., 2006. drought as an inciting mortality factor in scots pine stands of the valais, switzerland. ecosystems, 9:330-343. bolhar-nordenkampf, h.r., 1987. shoot morphology and leaf anatomy in relation to photosynthesis. in: coombs j, hall do, long sp, scurlock jmo (ed) techniques in bioproductivity and photosynthesis, pergamon press, oxford. brown, j.d. and lilleland, o., 1946. rapid determination of potassium and sodium in plant material and soil extract by flame photometry. proc amer soc hort sci, 73:813. damatta, f., loos, r.a., silva, e.a., loureiro, m.e. and ducatti, c., 2002. effects of soil water déficit and nitrogen nutrition on water relations and photosynthesis of pot-grown coffea canephora pierra. trees, 16:555-558. dias, m.c. and bruggemann, w., 2010. limitations of photosynthesis in phaseolus vulgaris under drought stress: gas exchange, chlorophyll fluorescence and calvin cycle enzymes. photosynthetica, 48:96-102. duan, b.l., lu, y.w., yin, c.y., junttila, o. and li, c.y., 2005. physiological responses to drought and shade in two contrasting picea asperata populations. physiol plant, 124:476-484. elsheery, n.i. and cao, k.f., 2008. gas exchange, chlorophyll fluorescence and osmotic adjustment in two mango cultivars under drought stress. acta physiol plant, 30:769-777. borah et al. /journal of tropical forestry and environment vol. 9, no. 02 (2019) 21-35 33 farooq, m., basra, s.m.a., wahid, a., cheema, z.a., cheema, m.a. and khaliq, a., 2008. physiological role of exogenously applied glycinebetaine in improving drought tolerance of fine grain aromatic rice (oryza sativa l.). journal of agronomy and crop science, 194:325-333. faye, i., diouf, o., guissé, a., sène, m. and diallo, n., 2006. characterising root responses to low phosphorus in pearl millet [pennisetum glaucum (l.) r. br.]. agronomy journal, 98:1187-1194. fordyce, i.r., duff, g.a. and eamus, d., 1995. the ecophysiology of allosyncarpia ternate (myrtaceae) in northern australia: tree physiognomy, leaf characteristics and assimilation at contrasting sites. australian journal of botany, 43:367-377. galmes, j., abadia, a., medrano, h. and flexas, j., 2007. photosynthesis and photoprotection responses to water stress in the wild-extinct plant lysimachia minoricensis. environmental and experimental botany, 60:308-317. ghaderi, n. and siosemardeh, a., 2011. response to drought stress of two strawberry cultivars (cv. kurdistan and selva). horticulture, environment, and biotechnology, 52:6-12. gowda, m.a., 1998. studies of sensitivity of some olive varieties to drought. dissertation, m. sc., hort dept, fac agric, minia university, egypt. greenwood, d.r., scarr, m.j. and christophel, d.c., 2003. leaf stomatal frequency in the australian tropical tree neolitsea dealbata (lauraceae) as a proxy measure of atmospheric co2. palaeoecology, 196:375-393. hassan, a.a., 1998. effect of drought on fruit seedlings. dissertation, m. sc., al-azahar university, cairo, egypt. hiscox, j.d. and isrealstam g.f., 1979. a method for extraction of chlorophyll from leaf tissues without maceration. canadian journal of botany, 57:1332-1334. hong, z., lakkineni, k. and zhang k., verma d.s.p., 2000. removal of feedback inhibition of ^1pyrroline-5-carboxylate synthetase results in increased proline accumulation and protection of plants from osmotic stress. plant physiology, 122:1129-1136. hunt, r., 1990. basic growth analysis. unwin hyman ltd., london. jackson, m.l., 1958. soil chemical analysis. prentice-hall, inc. englewood cliffs, usa. jaleel, c.a., gopi, r., sankar, b., gomathinayagam, m. and panneerselvam, r., 2008a. differential responses in water use efficiency in two varieties of catharanthus roseus under drought stress. comptes rendus biologies, 331:42-47. jaleel, c.a., sankar, b., murali, p.v., gomathinayagam, m., lakshmanan, g.m.a. and panneerselvam, r., 2008b. water deficit stress effects on reactive oxygen metabolism in catharanthus roseus, impacts on ajmalicine accumulation. colloids surf b: biointerface, 62:105-111. klute, a., 1986. methods for soil analysis, part 1, physical and mineralogical methods, second edition. american society of agronomy, agronomy monographs 9, madison, wisconsin, 1188. kusaka, m., ohta, m. and fujimura, t., 2005. contribution of inorganic components to osmotic adjustment and leaf folding for drought tolerance in pearl millet. physiologia plantarum, 125:474489. larcher, w. (2006). physiological plant ecology. 4th ed. rima, são carlos, 50. liu, c., liu, y., guo, k., fan, d., li, g., zheng, y., yu, l. and yang, r., 2011. effect of drought on pigments, osmotic adjustment and antioxidant enzymes in six woody plant species in karst habitats of south western china. environmental and experimental botany, 71:174-183. manivannan, p., abdul, jaleel c., sankar, b., kishorekumar, a., somasundaram, r., lakshmanan ,g.m.a., panneerselvam, r., 2007. growth, biochemical modifications and proline metabolism in helianthus annuus l. as induced by drought stress. colloids surfaces b: biointerfaces, 59:141149. 34 mansour, m.m.f., 1998. protection of plasma membrane of onion epidermal cells by glycine betaine and proline against nacl stress. plant physiology and biochemistry, 36:767-772. mengel, k., 2007. potassium. in handbook of plant nutrition. 1st ed. crc taylor and francis, ny, 91120. mengel, k. and kirkby, e.a., 2001. principles of plant nutrition, 4th ed. international potash institute, switzerland, 687. mohammadkhani, n. and heidari, r., 2008. drought-induced accumulation of soluble sugars and proline in two maize varieties. world applied sciences journal, 3:448-453. moustafa, a.h.a., 2002. studies on the irrigation of olive trees grown in new reclaimed soils. ph.d. thesis fac. agric., zagazig university, egypt. munne-bosch, s. and alegre, l., 2000. changes in carotenoids, tocopherols and diterpenes during drought and recovery and the biological significance of chlorophyll loss in rosmarinus officinalis plants. planta, 207:925-931. nomir s.a., 1994. physiological studies on kaki. ph. d. thesis., fac. agric. zagazig university, egypt. novozamsky, i., van, eck r., ch. van schouwenburg, j. and walinga, i., 1974. total nitrogen determination in plant material by means of the indophenol blue method. netherlands journal of agricultural science, 22:3-5. panse, v. g. and shukhatme, p.v., 1967. statistical procudures for agricultural worker, icar, new delhi. peng z. and lu q., verma d.p., 1996. reciprocal regulation of ^1-pyrroline-5-carboxylate synthetase and proline dehydrogenase genes controls proline levels during and after osmosis stress in plants. molecular genetics and genomics, 253:334-341. petite, m.a., moro, g.b., murua, g.c., lacuesta, m. and rueda, m.a., 2000. sequential effects of acidic precipitation and drought on photosynthesis and chlorophyll fluorescence parameters of pinus radiate d. don seedlings. journal of plant physiology, 156:84-92. piper, c.s., 1950. soil and plant analysis. international science publisher, inc. new york. 368. radford, p.j., 1967. growth analysis formulae their use and abuse. crop science, 7:171-175. restrepo-diaz, h., benlloch, m. and fernández-escobar, r., 2008. plant water stress and k + starvation reduce absorption of foliar applied k + by olive leaves. scientia horticulturae, 116:409-413. sardans, j. and penuelas, j., 2004. increasing drought decreases phosphorus availability in an evergreen mediterranean forest. plant soil, 267:367-377. sardans, j., peñuelas, j. and ogaya, r., 2008. drought’s impact on ca, fe, mg, mo and s concentration and accumulation patterns in the plants and soil of a mediterranean evergreen quercus ilex forest. biogeochemistry, 87:49-69. shao, h.b., chu, l.y., shao, m.a., abdul, jaleel c. and hong-mei, m., 2008. higher plant antioxidants and redox signaling under environmental stresses. comp rend biol, 331:433-441. shaheen, m.a., hegaz, a.a. and hmmam, i.s.a., 2011. effect of water stress on vegetative characteristics and leaves chemical constituents of some transplants olive cultivars. americaneurasian journal of agriculture and environmental science, 11:663-670. smirnoff, n., 1993. the role of active oxygen in the response to water deficit and desiccation. new phytologist, 125:27-58. taiz, l.and zeiger, e., 2002. plant physiology, 3rd edn. sinauer associates, inc., publishers, massachusetts. taiz, l. and zeiger, e., 2006. plant physiology. 4th ed. sinauer associates, inc., publishers, massachusetts. temminhhoff, e.e.j.m. and houba, v.j.g., 2004. plant analysis procedures. second edition, kluwer academic publishers. dordrecht, boston, london, 179. borah et al. /journal of tropical forestry and environment vol. 9, no. 02 (2019) 21-35 35 vaishnaw, v., mohammad, n., wali, s.a., kumar, r., tripathi, s.b., negi, m.s. and ansari, s.a., 2015. aflp markers for analysis of genetic diversity and structure of teak (tectona grandis) in india. canadian journal of forest research, 45:297-306. van mantgem, p.j., stephenson, n.l., byrne, j.c., daniels, l.d., franklin, j.f., fule, p.z., harmon, m.e., larson, a.j., smith, j.m., taylor, a.h. and veblen, t.t., 2009. widespread increase of tree mortality rates in the western united states. science, 323:521-524. verbruggen, n., hua, x.j., may, m.m. and vanmontagu, m., 1996. environmental and developmental signals modulate proline homoeostasis: evidence for a negative transcriptional regulator. proceedings of the national academy of sciences of the united states of america, usa 93, 87878791. verhaegen, d., fofana, i.j., logossa, z.a. and ofori, d., 2010. what is the genetic origin of teak (tectona grandis l.) introduced in africa and in indonesia? tree genetics and genomes, 6:717733. weatherley, p.e., 1950. studies in the water relations of the cotton plant. i. the field measurement of water deficits in leaves. new phytologist, 49:81-87. tejavathi et al. /journal of tropical forestry and environment vol. 9, no. 02 (2019) 101-107 __________________________________________ *correspondence: tejavathi_hanu@yahoo.com tel: +91 9448924734 issn 2235-9370 print/issn 2235-9362 online © university of sri jayewardenepura 101 studies on the factors that restrict sexual reproduction and fruit setting in memecylon flavescens: an endangered taxon d.h. tejavathi1*, b.s. sumalatha1, r. nijagunaiah1, p. anitha2, k. gayatramma3 1department of botany, bangalore university, bangalore, india. 2department of botany, bms college for women, basavanagudi, bangalore, india. 3department of botany, mes college, malleswaram, bangalore, india date received: 26-04-2019 date accepted: 20-12-2019 abstract memecylon flavescens gamble is an endangered taxon of nilgiri region of western ghats. extensive survey in the study areaavalanche, ooty made during 2015-18 has revealed a few interesting aspects about the sexual reproductive cycle. fruit setting is substantially very low though profuse flowering occurs. flowers are hermaphrodite, actinomorphic, tetramerous, pin type and protogynous, favouring crosspollination. pollen fertility as assessed by alexander’s differential staining is about 30%. sections of flower buds have revealed the infestation by undescribed gallmidge (diptera: cecidomyiidae). in 90% of the flower buds observed, gall midge galleries are seen at various levels in the flower bud, destroying the reproductive organs by larval feeding. hence, negligible fruit setting is mainly due to gallmidge infestation. protogynous nature and low percent of pollen fertility are added factors aggravating the effect on fruit setting. keywords: memecylon flavescens, endangered, protogynous flower, gall midge infestation 1. introduction the genus memecylon l. belongs to the family melastomataceae includes more than 300 species distributed mainly in the old world tropics (renner et al., 2007). in india, it is represented by 34 species, of which 18 species are endemic to western ghats and four species are endangered (gamble 1919, sivu et al., 2014). memecylon flavescens gamble, is endemic to western ghats and categorised under ‘endangered’ with iucn id-31203. gamble for the first time described this taxon based on his own collections from sispara in 1884 (2133 msl), avalanche (2186 msl) and kundah in 1885 (2133 msl). murugan et al., in 2002 have reported the species from kothayar and mahendragiri. sispara is at present identified under mukruthi national park, while kothayar and mahendragiri forest ranges are come under kanyakumari wildlife sanctuary and nelli wildlife sanctuary respectively. avalanche has been recognised as reserve forest area, while kundah is completely transformed into tea plantations. since, entry into sispara, kothayar and mahendragiri is restricted, avalanche was selected as our study area. though avalanche is categorised under reserve forest area, habitat destruction is continuously happening by various anthropological interferences. introduction of wattles in the early part of 20thcentury is another major threat to the survival of natural flora (seshana, 2003). a patch of 40 individuals of m.flavescens was located, identified, and recorded through extensive survey of the permitted study area (fig.1a). frequent visits to the study area for three consecutive years from 2015-2018 has revealed a few significant aspects on flowering and fruiting behaviour. though profuse flowering occurs during november to february, fruit setting is negligible. withering of ovaries was noticed before the setting of fruit. doi: https://doi.org/10.31357/jtfe.v9i2.4472 102 we could collect only 21 fruits during the tenure of three years of study period. hence, the present investigation is an attempt to identify the factors responsible for very low percent of fruit setting by analysing flower morphology, pollen fertility in addition to histological studies of flower buds of various stages. 2. material and methods 2.1 histology-flower buds flowers/flower buds of various stages were fixed in faa (formalin: acetic acid: ethyl alcohol) for 48h and transferred to 70% alcohol for preservation. customary paraffin technique was followed. microtome sections were taken at 12-15 µm thick and stained with haidenhain’s haematoxylin and counter stained with orange-g. photomicrographs were taken with cannon camera using leitze binocular inverted microscope. 2.2 alexander differential staining to assess pollen fertility (alexander, 1980) alexander differential stain was prepared by mixing the following: 1. ethanol (96%)-20 ml 2. distilled water-50 ml 3. glycerol-40 ml 4. acid fuchsin-100 mg 5. phenol-5 g 6. lactic acid-2 ml pollen is dusted on to 1-2 drops of stain on slides and warmed lightly before placing the cover slip. the cover slip was sealed with fixogum to prevent evaporation. slides were examined after 15-30 minutes. incubation at 50o c for 2-4 h, makes the stain deepens. 2.3 modified cellophane method using peg 10,000 in brewbaker and kwack’s medium for in vitro pollen germination (shashikumar, 2005) non-water proof cellophane strips measuring about 2.0-2.5 cm2 having a thickness of 0.01 mm were soaked in nutrient medium containing sucrose (10%), polyethylene glycol (10%), boric acid (100 ppm), calcium nitrate (300 ppm) potassium nitrate (100 ppm) and magnesium sulphate (200 ppm) for 10-15 min. soaked each cellophane strip was placed on one side of a clean micro slide. excess medium was drained off, using blotting paper. the slide with cellophane soaked in the germination medium was dried at room temperature. pollen were dusted uniformly on the cellophane and enclosed in a petri plates having filter paper lining on both the plates. the filter paper was moistened with distilled water to provide a 100% humid environment. the petri plates were incubated in the dark at 26±2o c for varied periods. after incubation, the cellophane strip with pollen was stained with a drop of alexander’s stain. a cover slip, slightly bigger than the cellophane strip was placed on the slide and sealed with fixogum. the slide was observed under binocular leitz microscope to record the percent and to measure the pollen tube length by ocular micrometer. 3. results and discussion perusal of literature and consultation of various herbaria (cal, cali, dd, frc, kfri, mh, pcm, tbgt) revealed that the species is known by only seven collections viz., gamble 14,268 and sivu 65,126 from sispara, gamble 16,161 and 16,168 from avalanche; gamble 20581 and mathew pm 34,073 from western slope of nilgiri ranges, adjoining nilambur forests from kundah and murugan xch 12,630 from upper kothayar and mahendragiri forest range. gamble collections are represented in k, while others are in tbgri, except murugan xch 12,630 which is deposited in st. xavier college, tirunelveli. duplicate of the former three collections of gamble are in cal and that of the last one is in mh. based on the status of preservation and hand drawings of gamble on the herbarium, das et al., 2013 have considered the tejavathi et al. /journal of tropical forestry and environment vol. 9, no. 02 (2019) 101-107 103 gamble 14,268 herbarium as lectotype. after gamble, no other collector has reported this taxon from avalanche, until we rediscovered in 2013 from the type locality. 3.1 flower morphology, percent pollen viability and germination flowering was observed in only one plant among 20 of almost same age during our first visit to the study area, 10 plants in the second year, and 6 plants in third year. variation in the number of plants that flower in each year indicate the inconsistency in flowering behaviour prevailing in this taxon. figure 1. memecylon flavescens; a-google satellite image of the location; b-twigs of the plants showing normal flower with insect infested flowersarrow marked; c and d-a twig with a flower and mature fruit. 104 flowers are hermaphrodite, actinomorphic, pin type, protogynous, blue in colour, in axillary clusters, shortly pedicellate; calyx 4, companualte, obscurely lobed; petals 4, ovate-orbicular; stamens 8, epipetalous, filaments 2.5-3.0 mm long; ovary syncarpous, 7-8 carpels, single locule, 7-8 ovules, axile placentation; berry globose, violet blackish in colour (figure 1b-d). figure 2. flower morphology; a-section of a flower showing protogynous nature; b-section of a flower showing gland on horn shape appendage of the connective; c-larvae on flower bud. the protogynous and pin type flower usually favours cross-pollination as pistil maturity occurs before anthesis and stigma loses its receptivity prior to anther dehiscence (figure 2a). the filaments are shorter than style and are folded over in such a way that the microsporangia are facing downwards and far away from stigma. the connective of the anthers is prolonged at the back to form a characteristic horn shaped appendage as reported in memecylon heyneanum (subramanyam, 1949). each appendage has a gland facing the style in bud. glands are concave in shape and its outermost layer consists of narrow elongated palisade-shaped cells with conspicuous nuclei and dense cytoplasm (figure 2b). this looks like the secretary layer of the gland followed by two to three layers of compactly arranged parenchymatous cells. morley (1976) has considered these distinctive connective glands as one of the characteristic features of the members of memecyleae. earlier studies have described these glands as nectary (burck, 1891, tejavathi et al. /journal of tropical forestry and environment vol. 9, no. 02 (2019) 101-107 105 subramanayam, 1949, venkatesh 1955). however, buchmann and buchmann (1981) have characterised the secretion from the connective glands of mouriri myrtilloides and concluded that it is an elaiophore secreting oil rather than nectar as once believed. vogel (1969, 1971) was the first to describe the presence of oil glands in the flowers of some families; melastomataceae is one among them. the stamen elaeiophore of this nature are unknown in any other taxon of oil producing flowers (buchmann and buchmann, 1981). the glycerides secreted through this elaeiophore can be considered as floral rewards in addition to nectar and pollen. the pollen grains were stained with alexander differential stain (1980) to assess the percent of fertile pollen. aborted pollen are more in number, about 40%, which look green in colour, pale reddish coloured pollen with scanty cytoplasm were also observed amounting to 30%, the remaining 30% of pollen which are fertile are bright red in colour. initiation of pollen tube was recorded after 3-31/2 h of incubation. maximum pollen tube length of 185 µm was recorded after 5 h of incubation. low percent of pollen viability was recorded in several other members of melastomataceae. low pollen fertility in sexually reproducing forms may be partly caused by environmental factors as was observed in miconia pepericarpa, which has shown 42.4% fertility in one year and 88.8% in the following year (goldenberg and shepherd, 1998). subramanyam (1942) has observed sterile pollen grains with various stages of degeneration in leandra cordifolia, a member of melastomataceae. in miconia species (melastomataceae), partial and complete male sterility due to the formation of large number of abnormal pollen grains is considered to be related to apomixis (goldenberg and shepard, 1998; cortez et al., 2012). abnormal pollen grains leading to pollen sterility is a common factor that was reported in all the apomictic species of melastomataceae (cortez et al., 2012). 3.2 histology visual observations of flowers revealed two types; greenish violet and brownish-white coloured buds (figure 1b). these buds were processed for microtomy. observations of double stained sections have shown the occurrence of undescribed gall midge (diptera: cecidomyiidae) infestation. brownish-white coloured buds are heavily infested, while greenish-violet buds which look healthy, are at initial stages. thus, about 90% of the flower buds studied were infested with gall midge and the larvae have damaged the reproductive parts of the flower bud by vigorous feeding and formation of gallaries (figure 2c). large number of eggs and larvae with gallaries have observed at different levels in the flower bud (figure 3a-f). in some flower buds, microsporangia are infected and in others, ovaries. an extreme condition was seen in some flower buds, that containing only larvae and gallaries enclosed by petals. malformed anthers were also noticed in some flower buds because of gall midge infestation (figure 3b-d). kolesik et al., 2018 have observed gall midge infestation of flower buds in alstoemeria that has led to the malformed flowers; turned necrotic later. nearly 80% of the flower buds were infested in these ornamentals plants. not all the gall midges are pests. a few beneficial species of gall midge prey on aphids, mites, scale insects, and bark beetle larvae thereby protecting the plants from other pests. flower bud, fruit, and seedling feeding cecidomyiidae are considered as potential biological control agents to reduce the rate of spread of invasive weeds (adair et al., 2000). 106 figure 3. section of flower buds showing insect infestation and galleries at various levels. 4. conclusion protogynous nature of the flower, low percent of pollen fertility and severe gall midge infestation are the main factors leading to substantial reduction in fruit production. habitat loss due to various anthropological interferences and introduction of wattles in the early part of the 20th century in avalanche, study area could be additional factors result in the restriction of propagation/ multiplication through sexual mode of reproduction. acknowledgment authors are grateful to ministry of environment, forestry and climate change, new delhi for funding this work. especial thanks to dr. s.shashikumar, agm, avt natural products ltd., bangalore, for his help rendered at various stages. tejavathi et al. /journal of tropical forestry and environment vol. 9, no. 02 (2019) 101-107 107 references alexander, m.p., 1980. a versatile stain for pollen fungi, yeast and bacteria. stain technology, 55:13-18. adair, r.j., neser, s. and kdesik, p., 2000. australian seed-preventing gall midges (diptera: cecidomyiidae) as potential biological control agents for invasive acacia spp. in south africa, proceedings of the x international symposium on biological control of weeds, montana state university, bozeman, montana, usa, pp 605-613. burck, w., 1891. beitrage zur kenntnis der myrmekophilenp flanzen und der bedeutung der extranuptialen nectarine. annales du jardin botanique de buitenzong, 10:75-144. buchmann, s.l. and buchmann, m.d., 1981. anthecology of mouriri myrtilloides (melastomataceae: memecyleae), an oil flower in panama. biotropia, 13:7-14. cortez, p.a., carmello-guerreiro, s.m. and teixeira, s.p., 2012. understanding male sterility in miconia species (melastomataceae) a morphological approach. australian journal of botany, 60:506-516. das, m.d., maity, d. and parmanik, a., 2013. lectotypification of memecylon flavescens gamble (memecylaceae dc). taiwania, 58:217-220. gamble, j.s., 1919. flora of the presidency of madras. vol. 1. third edition. adlard and son, ltd. london, pp 503. goldenberg, r. and shepherd, g.j., 1998. studies on the reproductive biology of melstomataceae in “cerrado” vegetation. plant systematics and evolution, 211:13-29. kolesik, p., baker, g., hill, k., manners, a.g. and dijkstra, e., 2018. new species of gall midge (diptera: cecidomyiidae) damaging flower buds of ornamental alstroemeria plants. austral entomology, 57:285-291. murugan, c., manickam, v.s., josephine, m.m. and sundaresan, v., 2002. extended distribution of two rare and endangered taxa from tirunelveli hills, western ghats, tamil nadu. journal of bombay natural historical society, 99:545-546. morley, t., 1976. memecyleae (melastomataceae). flora neotropica, monograph, 15:1-295. mathew, p. and sivarajan, v.v., 1996. flora of nilambur. bishen singh mahendra pal singh, dehra dun, pp 270. renner, s.s., triebel, d., almeda, f., stone, d., ulloa, c., michaelangeli, f.a.r., goldenberg, r. and mendoza h., (eds.) 2007 onwards. mel names: a database with names of melastomataceae, http://www.melastomataceae.net/melnames/.accessed 25 april 2013. seshana, s. and sandilya, t., 2003. survey, rapid assessment and restoration of vegetation diversity within mukurthi national park, report, gurukula botanical sanctuary, kerala. shashikumar, s., 2005. studies on pollen biology of a few horticultural important plants. thesis, bangalore university, bangalore, india. sivu, a.r., ratheeshnarayana, m.k., pradeep, n.s., santhoshkumar, e.s. and pandurangan, a.g., 2014. a new species of memecylon (melastomataceae) from the western ghats, india. phytotaxa, 162:4450. subramanyam, k., 1942. gametogenesis and embryogeny in a few members of the melastomaceae. journal of the indian botanical society, 21:69-85. subramanyam, k., 1949. on the nectary in the stamens of memecylon heyneanum benth. current science, 18:415-416. venkatesh, e.s., 1955. the structure and dehiscence of the anther in memecylon and mouriri. phytomorphology, 5:435-440. vogel, s., 1969. flowers offering fatty oil instead of nectar. abstracts, xi. international botanical congress, seattle, usa. pp 229. vogel, s., 1971. olpruduzierende blumen, die durch olsammelnde bienen bestaubr werden. naturwissenschafren, 58:58. maduwanthi et al. /journal of tropical forestry and environment vol. 11 no. 1 (2021) 61-68 61 *correspondence: akmnishal@gmail.com tel: +94 714855365 © university of sri jayewardenepura impact of vermicompost as a base fertilizer for radish (raphanus sativus l.) cultivation a.k.m.r.b. maduwanthi*, b. karunarathna, i. wickramasingha department of crop science, faculty of agriculture, eastern university, chenkalady, sri lanka date received: 21-03-2020 date accepted: 28-06-2021 abstract higher dosages of chemical fertilizers and other plant growth regulators increased the crop yield, but at the same time cause detrimental effects for human beings and environment. usage of organic fertilizers has come forward to minimize the usage of synthetic fertilizers. a pot experiment was carried out in crop farm, eastern university, sri lanka in between february to july in 2019 to analyze the effect of vermicomposting on growth and yield of radish. the experiment was laid out in a completely randomized design (crd) with five treatments and four replicates. the experiment was comprised with treatments; planting radish in soil with synthetic fertilizers at recommended rate (t1), planting radish in soil mixed with vermicomposting in the rate 10 t/ha (t2), 8 t/ha (t3), 6 t/ha (t4) and 4 t/ha (t5). variety beeralu was used for the experiment. t4 gave maximum plant height and fresh weight of leaves at 2nd and 4th wap. number of leaves was maximum in t4 at 2nd wap. tuber length and fresh weight of tuberous root was superior in t4 at 2nd and 4th wap. dry weight of leaves was not significantly varied with different levels of vermicomposting while dry weight of tuberous roots gave higher values in t4 at 6th wap which was not significantly differed with control. t4 gave superior total yield of radish/pot at each weekly interval. as most of the growth and yield parameters are superior in t4, the study concludes that, the better rate of vermicomposting that can be used to plant radish in sandy regosol is 6 t/ha for the better performance of radish. keywords: vermicomposting, organic fertilizers, synthetic fertilizers, tuberous root, base fertilizer 1. introduction radish (raphanus sativus l.) belongs to genus raphanus, family brassicaceae or cruciferae originated from the central and western china and india (dongarwar et al., 2017). it has been identified as a widely held root vegetable in both tropical and temperate regions (samir et al., 2019). tuberous root is the most popular eating part of radish, while the entire plant is edible and the top leaf part can be consumed as a leafy vegetable (dongarwar et al., 2017). radish is a source of carbohydrates, sugars, dietary fibers, protein, and even some fat and fluoride (banihani, 2017). as well, radish is rich in vitamin c (ascorbic acid), vitamin a, folic acid and minerals such as potassium, calcium, iron and phosphorus which are important in human nutrition and health (dongarwar et al., 2017; samir et al., 2019). radish is popular to use as a household remedy in order to treat many diseases such as jaundice, gallstone, liver diseases, rectal prolapse, indigestion, and other gastric pains. not only that, radish contains unique bioactive compounds such as glucosinolates and isothiocyanates that have been recently known to be important in health benefits to humans (banihani, 2017). the degradation and pollution of soil and water bodies due to excess use of chemical fertilizers is a major concern nowadays. therefore, shifting to organic fertilizers as a substitute for chemical fertilizers is the best method to support sustainable agriculture (mahmud et al., 2020). when compared to inorganic fertilizers, the use of vermicompost is an essential alternative source of fertilizer with 62 environmental benefits, increased production, and improved crop quality (kiran et al., 2019). vermicompost can be prepared with the decomposition of waste things such as kitchen waste and agro residues. vermicompost has been identified as a product with high porosity, aeration, drainage, and water-holding capacity, as well the vast surface area with fine particles has offered vermicompost the ability of providing strong absorbability and retention of nutrients (saranraj and stella, 2012). when preparing vermicompost, important nutrients such as nitrogen, phosphorus, potassium, and calcium present in the raw material are transformed through microbial action into available forms for plants. vermicompost consist of macronutrients such as n, p, k (nitrogen 2-3%, phosphorus 1.55-2.25% and potassium 1.85-2.25%) and micronutrients with advantageous microbes (actinomycetes, azotobacter, rhizobium, nitrobacter and phosphate solubilizing bacteria, ranging from 102-106 per g of vermicompost) and plant growth regulators (auxins, cytokinins and gibberellins) which are required for plant growth (chaulagain et al., 2017). this study was conducted to evaluate how vermicomposting effect on growth and yield of radish. 2. materials and methods a pot experiment was carried out at the crop farm, eastern university, sri lanka, in februaryjuly in 2019 to appraise the influence of vermicompost on growth and yield of radish. crop farm of eastern university sri lanka located in the latitude of 70 430 and the longitude of 810 42e. it belongs to the agro ecological region of low country dry zone in sri lanka. the mean annual rainfall of the crop farm ranges from 1400 mm to 1680 mm and temperature varies from 30 0c to 32 0c. the soil type used was sandy regosol. this experiment was carried out using a completely randomized design (crd) with five treatments and four replicates. treatments were as follows. table 1: treatments imposed in the experiment treatments rate of application t1 (control) planting radish in soil with no vermicompost t2 planting radish in soil mixed with vermicompost in the rate 10 t/ha t3 planting radish in soil mixed with vermicompost in the rate 8 t/ha t4 planting radish in soil mixed with vermicompost in the rate 6 t/ha t5 planting radish in soil mixed with vermicompost in the rate 4 t/ha vermicompost was prepared by using the barrel method at the crop farm of eastern university by using fruit wastes such as banana, papaw and orange and crop residues obtained from the local market and other crop residues. thread sized red earthworms were collected from the animal farm at eastern university. at the beginning, 50 earthworms were introduced per barrel. it was kept for 3 months for the decomposition prior to use. plastic pots with volume 11 liter were filled with soil leaving 1/3rd from the top and vermicompost was mixed at each rate in accordance with treatments two days before planting. basal was applied two days before planting, at the rate of urea 90 kg/ha, triple super phosphate (tsp) 110kg/ha and muriate of potash (mop) 65 kg/ha for control treatment (t1) according to the recommendation of department of agriculture (doa), sri lanka and vermicompost was applied according to the treatment (t2-t5).three seeds of radish variety beeralu were planted per one pot. top dressing was incorporated with soil three weeks after planting, at the rate of urea 90 kg/ha and muriate of potash (mop) 65 kg/ha for all treatments in accordance with doa, sri lanka. all the agronomic practices such as weeding and irrigation were done according to the doa, sri lanka. parameters such as plant height, tuber length, number of leaves per plant, fresh weight of leaves and tuber and dry weight of leaves and tuber were measured at two weeks interval up to three readings. plant height was measured from the tip of the plant to the ground level. collected data was analyzed using sas for continuous data and minitab for discontinuous data. 63 3. results and discussion 3.1 plant height the plant height showed significant difference (p<0.05) at 2nd and 4th week after planting (wap). the plant height in t3 and t4 at 2nd and 4th wap were significantly greater compared to control (t1). the highest values were observed in t4 at 2nd wap (13.7 cm) and 4th wap (19.6 cm) (table 2). but at 6th wap, there was no any significant difference (p>0.05) in plant height in between treatments. that may be due to the insufficiency of vermicompost as it was not applied for top dressing. but, synthetic fertilizers were applied for all treatments. however, there was no significant difference (p>0.05) between t3 and t4. taller plants may have been resulted due to the presence of humic acids and micro and macronutrients in vermicompost (pant et al., 2009). not only was that, the nitrification inhibition properties of vermicompost in the soil and rapid elongation and multiplication of cell with the adequate quantity of nitrogen may cause higher plant heights (khede et al., 2019). the plant height of radish was higher with the treatment of vermicompost than the control treatment (kumar and gupta, 2018). joshi et al. (2015) stated that, maximum plant height of potato (solanumtuberosum) was detected when vermicompost mixed with 100 % npks (chemical fertilizers). plant height of pak choi was higher with the application of non-aerated vermicompost than aerated vermicompost (pant et al., 2009). the results from khede et al. (2019) revealed that, the application of 50% recommended fertilizer dosage+25% vermicompost+25% poultry manure resulted significantly maximum plant height followed by the treatment with 50% recommended fertilizer dosage+50% vermicompost. table 2: plant height (cm) treatment 2nd wap 4th wap 6th wap t1 10.3±0.37c 15.5±1.15c 22.3±1.11 t2 12.9±0.40b 15.9±1.05bc 20.1±0.59 t3 13.4±0.41a 18.3±0.67a 22.4±1.12 t4 13.7±0.23a 19.6±1.12a 24.8±1.12 t5 11.0±0.49bc 16.6±0.73b 23.4±0.89 f test ** ** ns each value represents mean ± standard error of four replicates. f test: **: p<0.01; ns: not significant means followed by the same letter in each column are not significantly different according to the duncan’s multiple range test at 5% level. 3.2 tuber length tuber length showed significantly greater values (p<0.05) with the application of different rates of vermicompost at 2nd and 4th wap (table 3).tuber length was greater in t4 at 2nd wap which was par with t2 and t3 but was greater than control. at 4th wap also, tuber length was greater in t4 than control. but, at 6th wap, any significant difference was not observed in tuber length with the tested treatments. organic manures can reduce bulk density and increase porosity and water holding capacity of soil. also, solubalization of plant nutrients may increase with the addition of vermicompost thus, it will increase the uptake of n, p, and k (khede et al., 2019). both the facts can cause higher tuberous root lengths of radish. the maximum tuber length and was noticed in 75% of vermicompost concentration of potato (chandra, 2015). the treatment with vermicompost prepared from non-legume and legume waste at 2:1 ratio attributes with maximum root length in carrot (chatterjee et al., 2014). table 3: tuber length of radish (cm) treatment 2nd wap 4th wap 6th wap t1 7.7±0.22b 11.4±0.26c 18.3±0.50 t2 8.8±0.11a 12.9±0.24bc 19.9±1.22 t3 8.9±0.13a 13.5±0.29b 19.8±1.07 t4 9.2±0.23a 14.4±1.04a 20.8±2.14 t5 8.1±0.08b 13.4±0.54b 20.3±0.94 f test ** ** ns 64 each value represent mean ± standard error of four replicates. f test: **: p<0.01; ns: not significant means followed by the same letter in each column are not significantly different according to the duncan’s multiple range test at 5% level. 3.3 number of leaves the p values and chi–square values for number of leaves represent that there is a significant difference (p<0.05) at 2nd wap and no any significant difference at 4th and 6th wap (table 4). higher levels of nitrogen can increase the number of leaves per plant (silva et al., 2016). vermicompost contain nitrogen (2–3%) (sinha et al, 2009). as well, the release of nutrients through vermicompost is slower and thus enriching available nutrient pool also results higher number of leaves per plant. both the reasons may affect for higher number of leaves in t4 (6) than the control in 2nd wap. the number of leaves per plant is significantly superior in treatment t4 (50% rdf+50% vermicompost). according to the findings of khede et al. (2019), highest number of leaves was found in the treatment with 50 % recommended dose of fertilizers+50 % vermicompost. chandra (2015) cited that, no significant variation of number of leaves per plant of potato was found due to altered vermicompost levels. singh and chauhan (2009) found that, application of vermicompost to the french bean can promote the number of leaves of each plant. table 4: number of leaves per plant in radish treatment 2nd wap 4th wap 6th wap t1 4 6 7 t2 4 7 7 t3 4 7 7 t4 6 7 9 t5 5 7 8 p value 0.028 0.112 0.075 chi-square 10.91 7.50 10.00 3.4 fresh weights of leaves and tuberous roots in both 2nd and 4th wap, the highest values for fresh weight of leaves were resulted in t4. but, there was no any significant difference (p>0.05) at 6th wap. the higher nutrient content which increases the biomass in leaves, as well as the ability of vermicompost to increase the water holding capacity of soil which will lead to the higher content of water in leaves may be the reasons for the higher fresh weight of leaves in the radish treated vermicompost than the control. hasan et al. (2018) cited that, fresh weight of carrot leaves varied significantly due to different levels of vermicompost giving the superior in plants treated with vermicompost and minimum in control. the application of vermicompost among the different treatments of other organic manures showed significantly superior values over other treatments in respect to plant fresh weight of leaves as well compared to control (koodi, 2016). table 5: fresh weight of leaves of radish (g) treatment 2nd wap 4th wap 6th wap t1 0.49±0.07c 6.49±0.43c 22.19±1.25 t2 0.92±0.06b 6.04±0.24dc 23.08±1.09 t3 0.72±0.07bc 7.34±0.45b 21.92±0.60 t4 1.19±0.09a 9.84±0.11a 22.09±1.36 t5 0.89±0.07b 5.13±0.45d 21.52±0.95 f test ** ** ns each value represent mean ± standard error of four replicates. f test: **: p<0.01; ns: not significant means followed by the same letter in each column are not significantly different according to the duncan’s multiple range test at 5% level. 65 fresh weight of tuberous roots of radish was significantly affected (p<0.05) by the application of vermicompost (table 5). the superior value for fresh weight was obtained by t4 (0.22 g) which was at par with t3 (0.18 g) at 2nd wap. fresh weight of tuberous root at 4th and 6th wap (final harvesting) showed the similar pattern with higher value in t4 which was not significantly differed with t1 (control). better tuber yield in radish plant may be attributed with various components in vermicompost such as macro (n, p, k) and micro (ca, mg, mn, iron, sulfur, zinc and copper) nutrients, plant growth hormones (indole acetic acid, indole butyric acid, naphthalene acetic acid and gibberellic acid), vitamins (vitamin a, b1, b2, b3, c and e), enzymes, and many beneficial microbes such as nitrogen fixation bacteria and hormones synthesizing microbes such as azospirillumbrasilence, azospirillumlipoferum and azotobacterpaspali (ramamurthy et al., 2015). a considerably increased root weight of radish in the soil which incorporate 10% content of vermicompost was resulted in comparison with the soil without vermicompost (kovacik et al., 2018). fresh weight of roots of carrot was significantly higher with the different levels of vermicompost than without vermicompost (hasan et al., 2018). table 6: fresh weight of tuberous root of radish (g) treatment 2nd wap 4th wap 6th wap t1 0.14±0.04b 6.14±0.37a 80.22±1.82a t2 0.15±0.02b 5.45±0.31bc 72.20±2.62b t3 0.18±0.02ba 5.84±0.15bc 73.55±2.41b t4 0.22±0.01a 6.27±0.46a 84.82±3.15a t5 0.14±0.02b 3.99±0.12c 62.65±2.40c f test * * * each value represent mean ± standard error of four replicates. f test: *: p<0.05 means followed by the same letter in each column are not significantly different according to the duncan’s multiple range test at 5% level. 3.5 dry weight of leaves and tuber root there was no significant difference (p>0.05) in leaf dry weight,however, asignificant difference (p<0.05) was observed in tuberous root dry weight at harvest at 6th wap. with the higher availability of nitrogen in vermicompost with the combination of recommended dose of synthetic fertilizers applied as top dressing may have produced the higher dry weight of radish compared to the control. dhananjaya (2007) recorded that, the highest dry weight of leaves per plant was recorded with the application of poultry manure at 1.25 t per ha (50%)+vermicompost at 1.75 t per ha (50%). contradictory to the present experiment, kiran et al. (2016) cited that, maximum dry weight of leaves of radish was produced with the sole application of npk (synthetic fertilizers). dry matter of leaves was higher in radish plants treated with vermicompost than the control treatment without organic manures (uddain et al., 2010). table 7: dry weight of leaf and tuberous root of radish (g) at 6th wap treatment leaf tuberous root t1 2.08±0.34 7.32±1.09a t2 1.98±0.47 5.20±1.20b t3 1.96±0.47 5.01±1.40b t4 2.03±0.61 7.51±1.40a t5 1.86±0.39 4.37±1.21c f test ns * each value represent mean ± standard error of four replicates. f test: ns: not significant; *: p<0.05 means followed by the same letter in each column are not significantly different according to the duncan’s multiple range test at 5% level. 66 table 7 expresses that there was significant difference (p<0.05) in dry weight of root at 6th wap. t4 showed the greatest tuber dry weight compared to other treatments which was statistically similar to the t1 control (table 7). organic fertilizers convey almost all micro and macronutrients needed for the plants growth (koodi, 2016). vermicompost is also an organic fertilizer with lots of nitrogen, phosphorus and potassium as well as micronutrients (chaulagain et al., 2017). it may cause to increase the dry weight of tuberous roots in radish over control. application of poultry manure at 1.25 t per ha (50%)+vermicompost at 1.75 t per ha (50%) produced significantly highest dry weight of roots (dhananjaya, 2007). the treatment with vermicompost (50%)+poultry manure (50%) produced highest dry weight of roots of radish (kumar et al., 2014). the maximum and significantly higher dry weight of radish root was recorded in 50% recommended dosage of fertilizers+25% vermicompost+25% poultry manure, followed by 50% recommended dosage of fertilizers+50% vermicompost (khede et al., 2019). 3.6 total yield total radish yield/pot showed significant difference (p<0.01) at each weekly interval giving the superior values for the t4 as shown in the table 8. the vermicompost application favored the metabolic and auxin activities in plant and resulting in increased the total yield of radish (mali et al., 2018). yield of beetroot was superior with the application of vermicompost than the control (kibatu and mamo, 2014). getaneh and mezgebu (2019) investigated that, there was no any significant difference in total yield of carrot when grown under the combination of synthetic nitrogen and vermicompost. table 8: total yield of radish/pot (g) treatment 2nd wap 4th wap 6th wap t1 0.63±0.09c 12.63±0.60c 102.42±1.36b t2 1.07±0.08b 11.48±0.45c 95.28±0.66b t3 0.90±0.09b 13.18±0.51b 95.47±1.69b t4 1.41±0.08a 16.11±0.54a 106.91±1.77a t5 1.03±0.08b 9.11±0.34c 84.17±1.26b f test ** ** ** each value represent mean ± standard error of four replicates. f test: **: p<0.01 means followed by the same letter in each column are not significantly different according to the duncan’s multiple range test at 5% level. 4. conclusion the results from the experiment showed that vermicomposting played a significant role in the growth and yield in radish. it was found that most of the growth and yield parameters were affected with different levels of vermicomposting.t4 gave maximum plant height and fresh weight of leaves at 2nd and 4th wap. number of leaves was maximum in t4 at 2nd wap. tuber length and fresh weight of tuberous root was superior in t4 at 2nd and 4th wap. dry weight of leaves was not significantly varied with different levels of vermicomposting while dry weight of tuberous roots gave higher values in t4 at 6th wap which was not significantly differed with control. total yield of radish/pot was greater in t4 at each weekly interval. the study concludes that, the 6 t/ha rate of vermicomposting as basal with recommended inorganic top dressing can be suggested as the most appropriate rate for better performance of radish. according to the present results, the usage of synthetic fertilizers can be reduced by using vermicomposting as a basal fertilizer for the production of radish. it will be eco-friendly and make safe for human health to some extent. 67 references banihani, s.a., 2017. radish (raphanus sativus) and diabetes. nutrients, 9: 1014. chandra, g., 2015. influence of vermicompost on growth, yield and processing quality of potato varieties. chaulagain, a., dhurva, p., and lamichhane, g.j., 2017. vermicompost and its role in plant growth promotion. international journal of research, 4: 849-864. chatterjee, r., bandyopadhyay, s. and jana, j.c., 2014. evaluation of vegetable wastes recycled for vermicomposting and its response on yield and quality of carrot (daucus carota l.). international journal of recycling of organic waste in agriculture, 3: 60. dongarwar, l.n., kashiwar, s.r., ghawade, s.m., and dongarwar, u. r., 2017. performance of different radish (raphanus sativus l.) varieties in black soils of vidharbha-maharashtra. international journal of plant & soil science, 20: 1-9. dhananjaya, j., 2007. organic studies in radish (raphanus sativus l.) varieties. department of horticulture collage of agriculture, dharwad university of agriculture science, dharwad580, 5: 12-13. getaneh, t. and mezgebu, a., 2019. integrated effect of nitrogen and vermicompost levels on yield and yield components of carrot (daucus carota l.) at woreta, northwestern ethiopia. journal of horticulture and forestry, 11: 97-103. hasan, m.m., hakeem, k.r., ali, m.a., rubel, m.m.k., shah, m. and alzahrani, y., 2018. influences of vermicompost and organic mulching on growth, yield and profitability of carrot (daucus carota l.). journal of agriculture biotechnology, 3: 1. joshi, r., singh, j. and vig, a.p., 2015. vermicompost as an effective organic fertilizer and biocontrol agent: effect on growth, yield and quality of plants. reviews in environmental science and bio/technology, 14: 137-159. khede, k., kumawat, a., and tembare, d., 2019. effect of organic manures, fertilizers and their combinations on growth, yield and quality of radish (raphanus sativus l.) cv. japanese white. international journal of current microbiology and applied sciences, 8: 400-405. kibatu, t., and mamo, m., 2014. vermicompost and vermiwash on growth, yield and yield components of beetroot (beta vulgaris l.). world applied sciences journal, 32: 177-182. kiran, m., jilani, m.s., waseem, k. and sohail, m., 2016. effect of organic manures and inorganic fertilizers on growth and yield of radish (raphanus sativus l). pakistan journal of agricultural research, 29: 4. kiran, p., jaison, m., sridhar, d., 2019. vermicomposting and its uses in sustainable agriculture. 5: 75-88. koodi, s., 2016. effect of plant densities and fertilization on growth, yield and quality of sweet potato (ipomoea batatas lam.). m.sc. thesis. sri karan narendra agriculture university, jobner. kovacik, p., salamun, p., and wierzbowska, j., 2018. vermicompost and eisenia foetida as factors influencing the formation of radish phytomass. agriculture (poľnohospodárstvo), 64: 49-56. kovshov, s.v., and iconnicov, d.a., 2017. growing of grass, radish, onion and marigolds in vermicompost made from pig manure and wheat straw. indian journal of agricultural research, 51: 327-332. kumar, a., and gupta, r.k., 2018. the effects of vermicompost on growth and yield parameters of vegetable crop radish (raphanus sativus). journal of pharmacognosy and phytochemistry, 7: 589-592. kumar, s., maji, s., kumar, s., and singh, h., 2014. efficacy of organic manures on growth and yield of radish (raphanus sativus l.) cv. japanese white. international journal of plant sciences, 9: 57-60. mahmud, m., abdullah, r., and yaccob, j.s., 2020. effect of vermicompost on growth, plant nutrient uptake and bioactivity of ex vitro pineapple (ananas comosus var. md2). agronomy, 10: 1-22. 68 mali, d.l., singh, v., sarolia, d.k., teli, s.k., chittora, a., and dhakar, r., 2018. effect of organic manures and bio-fertilizers on growth and yield of radish (raphanus sativus l.) cv. japanese white. international journal of chemical studies, 6: 1095-1098. pant, a.p., radovich, t.j.k., hue, n.v., talcott, s.t., and krenek k.a., 2009. vermicompost extracts influence growth, mineral nutrients, phytonutrients and antioxidant activity in pak choi (brassica rapa cv. bonsai, chinensis group) grown under vermicompost and chemical fertilizer. journal of science and food agriculture, 89: 2383-2392. ramamurthy, m., umavathi, s., thangam, y., and mathivanan, r., 2015. effect of vermicompost on tuber yield status of radish plant raphanus sativus l. international journal of advanced research in biological sciences, 2: 50-55. samir, s., vandana, d., manu, t., and singh, c. p., 2016. morphological evaluation of radish (raphanus sativus l.) varieties in foothill conditions of uttarakhand. international journal of agriculture sciences, 8: 3591-3593. saranraj, p., and stella, d., 2012. vermicomposting and its importance in improvement of soil nutrients and agricultural crops. novus natural science research, 1: 14-23. silva, p.f., matos, r.m., ediclecia, v., alencar, a.e.v., and neto, j.d., 2016. growth and plant mass of radish fertirrigated with different doses nitrogen. revista ceres, 63: 122-128. singh, n. i., and chauhan, j., 2009. response of french bean (phaseolus vulgaris l.) to organic manures and inorganic fertilizer on growth and yield parameters under irrigated condition. natural sciences, 7: 52-54. sinha, r.k., heart, s., valani, d., and chauhan, k.a., 2009. earthworms vermicompost: a powerful crop nutrient over the conventional compost & protective soil conditioner against the destructive chemical fertilizers for food safety and security. american-eurasian journal of agricultural & environmental science, 5: 14-55. uddain, j., chowdhury, s., and rahman, m.j., 2010. efficacy of different organic manures on growth and productivity of radish (raphanus sativus l.). international journal of agriculture, environment and biotechnology, 3: 1-5. perera / journal of tropical forestry and environment vol. 11 no. 01 (2021) 1-15 1 feature article origin and transmission of covid-19 as a negative outcome of anthropogenic ecocide d.l. perera cultural anthropology researcher abstract covid-19 has become a global health burden that costs millions of human lives and causes collapsing health systems due to overcrowded hospitals, emergency services, intensive care units and exhausted staffs during last two years. there are plenty of scientific studies published on the origin, transmission, spread and emergence of pathogenic agent of covid-19 as well as the prevention, diagnosis, management, prognosis of the clinical conditions of the infection. the relationship between ecosystem degradation and biodiversity loss associated with anthropocentric development model that facilitates the viable hosting atmosphere for vector-borne and zoonotic diseases is being revisited and reviewed in a wider aspect with respect to this pandemic. therefore covid-19 pandemic build up a vital platform for profound international responses with social, political, economic, and environmental implications that address social and economic development, climate change, and biodiversity issues together with public health. under the one health concept many international organizations work closely together with conservation experts and health professionals in research, capacity building and networking to reduce the likelihood of future pandemics. in this context scientists call for an integrated global action and rapid political response in ecosystem management with a multi-disciplinary approach for the future interventions by emphasizing the importance of environmental sustainability for controlling such outbreaks. keywords: covid-19, zoonotic dieseses, emerging infectious disease (eid), biodiversity loss, ecosystem balance 1. introduction the world health organization (who) officially declared the outbreak of corona virus disease 2019 (covid-19), a public health emergency of international concern in january 2020 and a pandemic on 11 march 2020, followed by lockdowns and quarantine measures around the world (who, 2020). the causative organism of covid-19, severe acute respiratory syndrome coronavirus 2 (sars-cov-2) was identified in wuhan, hubei province, china, in december 2019 with a high rate of human to human tranmission spread worldwide and leading to an ongoing global health crisis (chakraborty and maity, 2020; salian et al., 2021). according to khan et al., (2020) the cost and disruption of human lives caused by rising number of critical cases reported with more deaths where due to the pandemic are undeniable and numbers are still rising with an unpredictable and uncontrollable rate producing severe environmental and economic impacts (chakraborty and maity, 2020). with reference to many hypotheses related to origin of covid-19 pandemic who denied the lab-leak theory claimed by some skeptics and eventually confirmed the origin on the animal market (maxmen, 2021). as scientifically concluded that the covid-19 is a zoonotic disease and currently becoming a significant threat to human health and many similarities have been identified between other sars variants and therefore covid-19 virus has been named as sars-cov-2 (khan et al., 2020; chakraborty and maity, 2020; dhama et al., 2020; salian et al., 2021). recent zoonotic disease outbreaks include severe acute respiratory syndrome or sars (2002-2003), avian influenza or bird flu (2004), h1n1 or swine flu (2009), middle east respiratory syndrome or mers (2012), ebola (2013–2015), zika 2 virus (2015–2016) and the west nile virus (2019) (chin et al., 2020; schwartz, 2021). cutler et al., (2010) estimate that 60% of emerging human pathogens are zoonotic of which >71% have wildlife origins and can switch hosts by acquiring new genetic combinations associated with the changes in behavior or socioeconomic, environmental, or ecologic characteristics of the hosts. ostfeld (2009) alarms emerging zoonotic pathogen transmissions are triggered by current unprecedented habitat declines which should be prevented by preserving the intact ecosystems and their endemic biodiversity as generally reduce probability of future zoonotic emergence (keesing et al., 2010; smith and guégan, 2010; karesh et al., 2012; nazir et al., 2021; petrovan et al., 2021). in 1992 the who commission on health and environment published the report titled “our planet, our health” which made a clear warning on the newly emerging infectious diseases as negative outcomes of degraded environment which is again highlighted in the report of the who/fao/oie joint consultation on emerging zoonotic diseases in 2004 (who, 2004). another report “ecosystems and human well-being: health synthesis” in 2005 alarmed on an upturn in the rate of emergence or reemergence of infectious diseases caused by ecological malfunctions due to intensified human encroachments, reductions in biodiversity, particular livestock and poultry production methods and increased long-distance trade in wild animal species (who, 2005). the importance of a well-managed environment as clear as in human health is addressed in the report “our planet, our health, our future; human health and the rio conventions: biological diversity, climate change and desertification” published by who in 2012, with a reference to emerging zoonotic diseases. who and secretariat of the convention on biological diversity with un environment programme (unep) published “connecting global priorities: biodiversity and human health” in 2015 with an in-depth review on biodiversity conservation and insights on the emergence of infectious diseases associated with wildlife borne pathogens. the unep’s report titled "preventing the next pandemic: zoonotic diseases and how to break the chain of transmission" in 2016 and confirmed that 75 per cent of more frequently occurring outbreaks of new infectious diseases with a global concern are zoonotic and 80 per cent of pathogens infecting animals are “multi-host”. the unep identified the issue of zoonotic diseases as a key emerging issue of global concern and amplification increases with the intensification of human activities surrounding and encroaching into natural habitats, enabling pathogens in wildlife reservoirs to spill over to livestock and humans. the report emphasizes the critical relationship between a healthy environment and healthy people, and how human activities often undermine the long-term health and ability of ecosystems to support human well-being. scientific american on the 07th march, 2020 published an opinion and analysis article titled “an urgent call for a new relationship with nature” to mark the world wildlife day (march 3, 2021) on the theme of “forests and livelihoods: sustaining people and the planet”. in may 2020, the world health assembly in resolution wha73.1 requested the director-general of the world health organization (who) to continue to work closely with the world organisation for animal health (oie), the food and agriculture organization (fao) and countries, as a part of the one health approach, to identify the zoonotic sources of the viruses and the route of introduction to the human population, mode of transmission and the possible role of intermediate hosts. in december 2020, the european parliament issued a new report on the link between biodiversity loss and the increasing spread of zoonotic diseases and highlighted the importance of introducing policy options to reduce risks originating from wildlife trade. also a public hearing on the “facing the sixth mass extinction and increasing risk of pandemics: what role for the eu biodiversity strategy for 2030” was held on the 14th january 2021. according to the ipbes (2020) report currently an estimated 1.7 million undiscovered viruses to exist in mammal and avian hosts of which 540,000-850,000 could be transferred to humans and infect humans. emerging vector-borne pathogen transmission following habitat conversions and landscape modifications driven by anthropogenic trade and travel enhanced enzootic cycles facilitated perera / journal of tropical forestry and environment vol. 11 no. 01 (2021) 1-15 3 with ecological factors that support to mutate vector characteristics for evolutionary selective pressure to use of humans as transmission hosts (kilpatrick and randolph. 2012; guo et al., 2019; gibb et al., 2020). according to karesh et al., (2004) causal factors influencing the dynamics associated with emergence or reemergence of zoonoses are very important connected with wildlife trade in the industrialized world. many vector-borne diseases are arisen concurrently with the advent of agriculture and animal husbandry that create space for host populations and allow the maintenance of virulent pathogens by degrading natural buffers between humans and animals (jessica, 2006; ostfeld, 2009; smith and guégan, 2010; hassell et al., 2017; athni et al., 2021). dunk et al., (2019) describe the historical perspective of the impact of well-functioning natural ecosystems as an important factor for the human health when they have higher diversity of species and healthy space for symbiotic survival that do not host dangerous pathogens. from the beginning of this century the humans are increasingly being exposed to transmission of zoonotic diseases as the global wildlife trade and habitat destruction caused by human activities (jowell and barry, 2020). there are plenty of studies that suggest outbreaks of animal-borne illness become more frequent due to wildlife species threatened by exploitation or habitat loss caused by accelerated destruction of nature (taylor et al., 2001; weiss and mcmichael, 2004; karesh et al., 2004; woolhouse and gowtage-sequeria, 2005; keesing et al., 2006; jones, et al., 2008; ostfeld, 2009; keesing et al., 2010; smith and guégan, 2010; rhyan and spraker, 2010; morse et al., 2012; salkeld et al., 2013; murray and daszak, 2013; gottdenker et al., 2014; pfäffle et al., 2015; rubio et al., 2016; ostfeld, 2017; johnson et al., 2017; alexander et al., 2017; wilkinson et al., 2018; schmeller et al., 2020; kenyon, 2020; gibb et al., 2020; austin, 2021; mishra et al., 2021). 2. emerging infectious diseases and zoonosis the intergovernmental science-policy platform on biodiversity and ecosystem services (ipbes), a group of scientists from academia, governments, and nonprofits, hosted the science underlying through expert opinions to produce an assessment on connection between biodiversity loss and emerging infectious diseases (eids) (tollefson, 2020). in current global public health eids are a significant burden and having a negative impact on global economies. therefore researchers are working together with a redoubled effort to understand nexus between habitat loss and eids to predict and prevent future outbreaks (jowell and barry, 2020; khetan, 2020; nature, 2020; córdoba-aguilar et al., 2021). according to morand (2020) within last decade there is an increasing emergence of infectious disease outbreaks associated with biodiversity loss and livestock expansion due to growth of human population, transitions in diet, agricultural industrialization and the integration into the world trade (schmeller, 2020; keesing, 2021). keesing (2021) shows that zoonosis originated due to anthropogenic modification of nature represent a significant threat to global public health as well as economic growth and combatting eids has become a priority of health systems with a deliberate attention (morse et al., 2012; allen et al., 2017; ellwanger et al., 2019; gibb et al., 2020; schmeller, 2020; harrison et al., 2021). athni et al., (2021) illustrate the socio-ecological mechanisms influence on vector-borne diseases throughout the history and the increasing number of eids all over the world is caused by pathogens originated in wildlife and transmitted through wild hosts and vectors or infected domestic animals (rhyan and spraker, 2010; gottdenker et al., 2014; pfäffle et al., 2015; cunningham et al., 2017;). actual transmission of the pathogen to humans from a zoonotic host is the first pattern of transmission while direct vector-mediated human transmission is the second as the usual source of human infection followed by human-to-human transmission that may persist for long period (bengis et al., 2004; keesing et al., 2010). according to mackenzie and jeggo (2013) especially mammals and birds are reservoir hosts of enormous number of zoonotic viruses that are silent or asymptomatic in their natural hosts and crossspecies transmission might lead to human infection (woolhouse and gowtage-sequeria, 2005; white 4 and razgour, 2020). keesing and ostfeld (2021) suggest that increasing of possibility of spillover according to the hosts that determine patterns of pathogenic transmission and the process of transmission between susceptible species in human-dominated landscapes (daniels et al., 2007; ostfeld, 2009; hassell et al., 2017). alexander et al., (2017) highlight the eco-epidemiological aspect of spillover interface that depends on the diversity of pathogen life cycles and modes of transmission with broader geographic spread. viruses transmitted at high-risk animal-human interfaces during practices that facilitate mixing of diverse animal species significantly amplify the spillover and viruses with greater host plasticity in animal reservoirs demonstrate more human-to-human transmissibility and therefore high pandemic potential (kreuder et al., 2015; plowright et al., 2017; ellwanger et al., 2019; jowell and barry, 2020; modonesi, 2020). at the beginning of this millennia taylor et al., (2001) identify through literature 1415 species of infectious organism known to be pathogenic to humans, out of which 868 (61%) are zoonotic, and 175 species are considered to be associated with 'emerging' disease conditions. according to jowell and barry (2020) in the current reviews on causative factors of eids suggest that they are produced by human-induced environmental change that causes direct and indirect loss of biodiversity largely responsible for public health emergencies (daszak et al., 2001; weiss and mcmichael, 2004; ostfeld, 2009; salkeld et al., 2013; alexander et al., 2017; ostfeld, 2017; ellwanger et al., 2019; khetan, 2020; keesing and ostfeld, 2021). therefore recognition of the eco-epidemiologic circumstances involved in public health emergencies caused by zoonotic spillover and the transmission, amplification and spread of such diseases is a crucial step for surveillance and predicting future emergence risk (kreuder et al., 2015; plowright et al., 2017; ellwanger et al., 2019; jowell and barry, 2020). schwartz (2021) global emergence of novel viral infectious disease outbreaks are associated with higher forest fragmentation, concentrations of livestock, trending wet markets throughout many countries. recent findings indicate that human-livestock-wildlife interactions in china may form hotspots with the potential to increase sars-related coronavirus transmission from animals to humans. (rulli et al., 2021). nazir et al., (2021) show the impact of environmental factors such as air pollution for spreading the virus and potential role of pollutants in the mode of transmission (al huraimel et al., 2020; mohan et al., 2020). the bidirectional approach suggests that thermal properties of air may affect the transmissibility and viability of the sars-cov-2 especially during lockdown interventions and environmental conditions are beneficial in transmitting the virus beyond geographical borders (coccia, 2020; rahimi et al., 2020). morand and lajaunie (2021) explore that the rise of oil palm plantations at global scale play a key role in deforestation is a major cause of biodiversity loss may promote outbreaks of vector-borne and zoonotic diseases (vbzd) with a negative impact on human health (tollefson, 2020). according to experts the eids are more likely to be driven by ecological factors on which no extensive study is conducted and therefore an explicit analysis is needed for describing linkages between global temporal and spatial patterns of eids or 'eid hotspots' (jones, et al., 2008). recording ecological outcomes responsible for the majority of outbreaks caused by zoonotic pathogens, their vector hosts and mode of transmission is very important activity in surveillance of global eid context (smith and guégan, 2010; morse et al., 2012; smith, et al., 2014; pfäffle et al., 2015; athni et al., 2021; keesing and ostfeld, 2021). according to schmeller et al., (2020) wild animals host a vast reservoir of pathogens that can cause eid outbreaks due to negative outcomes of natural habitats disturbed by anthropogenic interferences which have an impact on both the pathogens and the mode of transmission to humans (allen et al., 2017; wilkinson et al., 2018; white and razgour, 2020; córdoba-aguilar et al., 2021). existing data suggest that zoonotic spillover is linked to human-induced changes in ecosystems leading to habitat destruction and land conversion that increase the interspecies contacts and host (faust et al., 2018; redding, et al., 2019; jowell and barry, 2020; khetan, 2020; schwartz, 2021). human-induced perera / journal of tropical forestry and environment vol. 11 no. 01 (2021) 1-15 5 landscape modifications influence the natural habitats and increase the land-use pressures that leads to the eid prevalence (brearley et al., 2013; murray and daszak, 2013; gottdenker et al., 2014; rubio et al., 2016; harrison et al., 2021; smith, 2021). 3. anthropocene and covid-19 the new era began with an irreparable damage produced by human activities on the nature ic referred as anthropocene where the symbiotic relationship between humans and environment is totally ruined and caused great biodiversity loss (lewis and maslin, 2015). the global biodiversity crisis due to degradation of ecosystems is emerged due to the loss of historical synergism between human populations and nature (johnson et al., 2017). o'callaghan-gordo and antó (2020) claim covid-19 as a side-effect of anthropocene and the best example of spillover event that eventually transformed into a pandemic. aronsson and holm (2020) suggest that adopting a multispecies perspective on novel pathogens cause eids that are associated with anthropogenic environmental changes at global scale. the great acceleration of human involvements in natural habitats and ecosystems was the major pathway of eid outbreaks in anthropocene (chin et al., 2020). there is a global need to establish strategies focused on the reduction of the frequency of zoonotic spillover as a fundamental cause eids and minimize facilitating factors of the transmission of pathogens (ellwanger and chies, 2021). carlson et al., (2021) call for multilateral and multidisciplinary cooperation at international level to achieve pandemic preparedness in the anthropocene policy updates for paving the way for stronger and sustainable global health governance, health systems, and scientific research. there is an urgent need to build an internationally agreed framework to ensure the preservation of natural habitats and the ecosystem services based on the positive link between global deforestation and outbreaks of vbzd that contribute to epidemics of infectious diseases (morand and lajaunie, 2021). barbier (2021) anthropogenic influence on ecosystems triggers eids such as covid-19 resulted due to zoonotic disease spillover and the best example of a potential outbreak directly related inter-species pathogen spillover (chin et al., 2020; gibb et al., 2020; kenyon, 2020; white and razgour, 2020; austin, 2021; delahay et al., 2021). borremans et al., (2019) suggest that ecosystem boundary areas are spatial hotspots where complex interactions between multiple species and higher rates of zoonotic disease spillover occur. since the spillovers are caused by habitat destructions land conversions increase the pressure on ecosystems and affect directly on public health burdens through zoonotic pathogen transmissions, potential sustainable ecological mechanisms must be explored (da silva et al., 2021). wu (2021) highlights ecosystem conversion, meat consumption, urbanization, and connectivity among cities and countries as the four basic environmental drivers of pandemics intensified in recent decades. this helps to explain the dynamics of the covid-19 pandemic and other recent eids that emerged from illegal wildlife trade and bush-meat market in line with deforestation (brancalion et al., 2020; kenyon, 2020; tollefson, 2020; austin, 2021). the recent outbreaks of eids were evidently linked with virus evolved from wildlife reservoirs linked to environmental disruption and their spread was triggered by economic globalization (mcneely, 2021). barouki et al., (2020) argue that the emergence and spread of sars-cov-2 appears to have a connection to urbanization, habitat destruction, live animal trade, intensive livestock farming and global travel. according to banerjee et al., (2021) the covid-19 is originated naturally, probably from bats with several theories about the ‘patient zero’ that revealed the connection between intensive food systems and zoonotic diseases. few of the studies have confirmed zoonotic links in the origin of sars-cov-2 and spillover events, transmission to humans and rapid spread of virus (dhama et al., 2020; banerjee et al., 2021; da silva et al., 2021; salian et al., 2021). 6 emergence of outbreaks of vbzds is becoming global public health concern with increasing frequency and consequences and having potentially long-lasting effects on human health with inevitable negative impacts on ecosystems. in this context it is evidently shown that the human-driven biological degradation as the main underlying reason that increases the anthropogenic impact on nature that exacerbates pandemic threats like covid-19 crisis (gibb et al., 2020; kenyon, 2020; schmeller et al., 2020; white and razgour, 2020; austin, 2021). human activities driving biodiversity degradation cycle are tightly linked with the socio-ecological factors based on contemporary livelihood and market patterns that contribute to reductions in the natural regulating capacities of ecosystem services to limit pathogen transfer (everard et al., 2020; smith, 2021). gibb et al., (2020) argues that the negative impact of human dominated ecosystems influenced with increasing population and anthropogenic activities as habitat fragmentation, deforestation, biodiversity loss, intensive agriculture and livestock farming, uncontrolled urbanization, pollution, climate change and bush-meat hunting and trading on the environment causes the emergence of pandemics (hassell et al., 2017; wilkinson et al., 2018; morand 2020; tollefson, 2020; white and razgour, 2020). zoonotic pathogens are leading to sustained human-to-human or vector-borne are currently becoming the greatest threats to human health as a result of anthropocentric ecosystems degradation, climate change, pollution and biodiversity loss (pfäffle et al., 2015; cunningham et al., 2017; ostfeld, 2017; wilkinson et al., 2018; gibb et al., 2020; jowell and barry, 2020; rahman et al., 2020; keesing and ostfeld, 2021; nazir et al., 2021; smith, 2021). 4. eco-epidemiological model and one health initiative mcmahon et al., (2018) highlight importance of understanding the nexus between the vbzds and environmental factors influencing the pathogen spillover and transmission within different ecological and cultural contexts for planning for one health to assess and manage to the emergence and impact of zoonosis in the anthropocene. in such strategy force of infection (foi) is a measure of the ease with which a pathogen reaches the human population and the disease ecology alters it within ecosystem categories such as domestic, peridomestic and sylvatic. jones et al., (2017) demonstrate the complexity and connectedness of epidemiological and eco-social processes with emergence, transmission and spread of vbzds that must be addressed by an increasing mode of research efforts with a multidisciplinary approach within the one health context (cunningham et al., 2017; zinsstag et al., 2020; cooke et al., 2021). all the mechanisms linked with pathogen characteristics and pathogen population and molecular evolutionary dynamics in different host species, and host response to infection are strongly influenced by eco-social processes, such as globalization and urbanization (athni et al., 2021; petrovan et al., 2021). ecosystem-based studies have suggested the link between the climate change and the incidence of vbzds is well understood from the beginning of this millennium and mechanisms that facilitate the pathogen transmission are aggravated by anthropogenic influences (weiss and mcmichael, 2004; mills et al., 2010; jowell and barry, 2020; athni et al., 2021). landscape epidemiology attributes related to landscape attributes, spatial patterns and habitat connectivity drive the pathways of pathogen transmission and influence spatial variations in vbzd risk or incidence. instead of the static view of the pathogenecity of landscapes more dynamic view emphasizing the spatial and temporal interactions between these agents at multiple scales are suggested as appropriate and susceptible for understanding of interactions between changes in ecosystems and human health (lambin et al., 2010; murray and daszak, 2013; gottdenker et al., 2014; rubio et al., 2016; hassell et al., 2017; guo et al., 2019; nazir et al., 2021; petrovan et al., 2021). roche et al., (2012) emphasize the timely need of a theoretical framework that takes into account realistic community assemblages that can be used to study the interaction between wildlife diversity and directly transmitted pathogen dynamics within a multi-host species epidemiological model. in this aspect integration of community perspective to study zoonotic prevalence and perera / journal of tropical forestry and environment vol. 11 no. 01 (2021) 1-15 7 circulation of pathogens for understanding ecological interactions among host species and predicting inter-species transmission rates and emergence events of vbzds are very important. kock (2013) highlight the global socio-ecological changes driven by sophisticated technology and global political economy that influence natural resource consumption rates in an unsustainable manner with negative impacts on the biosphere as the cause of imbalance balance between hosts and pathogens (woolhouse and gowtage-sequeria, 2005; gottdenker et al., 2014). for shifting this paradigm global political, social and economic systems need to be reassessed and epidemiology of vbzd must be readdressed in terms of demographics, agroecology, biodiversity with a precautionary approach to establish the health of natural ecosystems (córdoba-aguilar et al., 2021; de garine-wichatitsky et al., 2021; snedden et al., 2021). dirzo et al., (2014) names current global wave of anthropogenically driven biodiversity loss causes the major driver of global ecological change as "anthropocene defaunation" which leads to the sixth mass extinction. anthropogenic sixth mass extinction is accelerated by rapidly growing human pressures on the biosphere and having severe implications that increase the degradation of ecosystem services and decrease the public health security (ceballos, 2020). dunk et al., (2019) highlight report of 2015 lancet commission that alarmed enfeebled condition of the earth’s natural systems assigning the term “planetary health and concluded to receive the ongoing collaboration with experts and a range of stakeholders with existing monitoring processes for "the greatest global health opportunity of the 21st century" due to the climate change (watts et al., 2017). abiha et al., (2021) evidently highlight the positive effect of strategies like lockdowns on the natural habitats and wildlife which is referred as a the period of “great pause” or sometimes named as “anthropuase” has helped to recover environmental damage of caused by human activities (arora et al., 2020; buxton et al., 2020; rutz et al., 2020; zuluaga et al., 2021). zoonotic spillover requires several factors to align, including the ecological, epidemiological and behavioural determinants of pathogen exposure, and to prevent an occurrence of spillover of a pathogen there can be effective, affordable, durable and scalable solutions to set up a hierarchical series of barriers (alexander et al., 2017; plowright et al., 2017; sokolow et al., 2019). the destruction of natural habitats causing critical state of biodiversity is an important driver of emerging transmission of zoonotic pathogens that is more likely to occur in phylogenetically related hosts (modonesi, 2020; abiha et al., 2021). grange et al., (2021) developed spillover, a risk ranking framework and interactive web tool for estimating a risk score for wildlife-origin viruses and assessed 509,721 samples from 74,635 animals and ranked the spillover potential of 887 wildlife viruses in which sars-cov-2 was in the top 12 viruses. according to vandersmissen, and welburn (2014) zoonoses are included into one health movement, depends on forging strong links between human and animal health services, for implementing policies at the human-animal-environment interface. one health is an interdisciplinary approach integrating professionals from multiple disciplines that prescribes measures at local, regional, and national levels for mitigating emerging outbreaks of zoonotic infectious disease (konda et al., 2020; zinsstag et al., 2020; dykstra et al., 2021; snedden et al., 2021). sánchez et al., (2021) call for transdisciplinary approaches to provide a more holistic understanding of zoonotic spillover phenomena and subsequent emergence of vbzds that casue public health burden affects on long-lasting impacts on our social, economic, environmental and political systems. 'one health' disciplines including veterinary science and animal health, public health and medicine, ecology and evolution, environmental science, with broad conceptual scope can be used for identifying priority areas for further research interventions into zoonotic and filling the gaps in academic disciplines (dykstra et al., 2021). vbzd risks are ultimately interlinked with biodiversity crisis, climate change and water insecurity that need to be changed with rapid political responses and systemic policy changes at global 8 level (everard et al., 2020; smith, 2021). rahman et al., (2020) highlights covid-19 pandemic as a newly emerging zoonotic disease burden and recommend implementing one health measures for effective prevention and control of possible zoonosis in future (cooke et al., 2021; córdoba-aguilar et al., 2021; delahay et al., 2021). de garine-wichatitsky et al., (2021) suggest to adopt a socialecological system framework (sesf) based on a transdisciplinary definition of socio-ecological system health (sesh) to prevent and cope up with emerging health and environmental risks one health integrated approaches. plowright et al., (2021) recommend interdisciplinary collaborations and mechanistic focus on land use implications for zoonotic eids and to urgently formulate an integrated science-based policy and management measures for addressing human-induced habitat loss that is known to be the major driver of zoonotic pathogen spillover (snedden et al., 2021). the scientific underpinnings for effectively overcoming primary technical challenges, and advance policy and management issues to be implemented for reducing the risk of pathogen spillover from reservoir hosts and land use pressureinduced zoonotic pathogen infect-shed-spill-spread cascade must be a priority in research sector (rubio et al., 2016; guo et al., 2019; harrison et al., 2021; snedden et al., 2021). marselle et al., (2021) introduce four domains for better mechanistic understanding biodiversity as a cornerstone of human health and well-being as reducing harm, restoring capacities, building capacities and causing harm. with an understanding of range of pathways through which biodiversity influence human health, a policy framework based on evidences from across the natural, social and health sciences for fostering biodiversity-focused public health actions and reinforcing biodiversity conservation (de garine-wichatitsky et al., 2021; harrison et al., 2021; petrovan et al., 2021). cooke et al., (2021) highlights conservation physiology driven sustainable development interventions leading to win-win solutions based on integration of biodiversity conservation and public health are now becoming the timely needs of strategic planning of health systems. negative biodiversity changes influence and are mechanistically linked to the zoonotic pathogen spillover process and then global efforts can be initiated for effectively reframing the discussion to integrate the related goals of biodiversity conservation and spillover prevention (zinsstag et al., 2020; abiha et al., 2021; glidden et al., 2021; petrovan et al., 2021; snedden et al., 2021). clark (2020) emphasizes the linkage between the covid-19 pandemic and ecological connectivity as an international criminal of ecocide from transitional justice point of view. therefore pandemic brought profound international responses with social, political, economic, and environmental implications that address social and economic development, climate change, and biodiversity issues together with public health (mcneely, 2021). under the one health concept conservation physiologists work closely together with conservation experts and health professionals in research, capacity building and networking to reduce the likelihood of future pandemics (cooke et al., 2021). everard et al., (2020) suggest an integrated global action and rapid political response in ecosystem management in mitigating and managing the public health emergencies ultimately interlinked with biodiversity crises. current covid-19 pandemic provides learning for the future for policy-makers, organizations, and governments, in particular the importance of environmental sustainability for controlling such outbreaks (de garine-wichatitsky et al., 2021; mishra et al., 2021; petrovan et al., 2021). references abiha, u., phutela, s. and shukla, s., 2021. biodiversity conservation: an imperial need in combatting pandemic and healthcare emergencies. the impact of the covid-19 pandemic on green societies: 323. alexander, k.a., carlson, c.j., lewis, b.l., getz, w.m., marathe, m.v., eubank, s.g., sanderson, c.e. and blackburn, j.k., 2018. the ecology of pathogen spillover and disease emergence at perera / journal of tropical forestry and environment vol. 11 no. 01 (2021) 1-15 9 the human wildlife environment interface. in the connections between ecology and infectious disease, 5: 267-298. allen, t., murray, k. a., zambrana-torrelio, c., morse, s. s., rondinini, c., di marco, m., breit, n., olival, k. j. and daszak, p., 2017. global hotspots and correlates of emerging zoonotic diseases. nature communications, 8: 1124. aronsson, a. and holm, f., 2020. multispecies entanglements in the virosphere: rethinking the anthropocene in light of the 2019 coronavirus outbreak. the anthropocene review: 2053019620979326. arora, s., bhaukhandi, k.d. and mishra, p.k., 2020. coronavirus lockdown helped the environment to bounce back. science of the total environment: 140573. athni, t.s., shocket, m.s., couper, l.i., nova, n., caldwell, i.r., caldwell, j.m., childress, j.n., childs, m.l., de leo, g.a., kirk, d.g. and macdonald, a.j., 2021. the influence of vector borne disease on human history: socio‐ecological mechanisms. ecology letters, 24: 829-846. austin k. f. 2021. degradation and disease: ecologically unequal exchanges cultivate emerging pandemics. world development, 137: 105163. banerjee, a., doxey, a.c., mossman, k. and irving, a.t., 2020. unravelling the zoonotic origin and transmission of sars-cov-2. trends in ecology and evolution. barbier e. b., 2021. habitat loss and the risk of disease outbreak. journal of environmental economics and management, 108: 102451. barouki, r., kogevinas, m., audouze, k., belesova, k., bergman, a., birnbaum, l., boekhold, s., denys, s., desseille, c., drakvik, e. and frumkin, h., 2021. the covid-19 pandemic and global environmental change: emerging research needs. environment international, 146: 106272. bengis, r. g., leighton, f. a., fischer, j. r., artois, m., mörner, t. and tate, c. m., 2004. the role of wildlife in emerging and re-emerging zoonoses. revue scientifique et technique (international office of epizootics), 23: 497-511. borremans, b., faust, c., manlove, k. r., sokolow, s. h. and lloyd-smith, j. o., 2019. cross-species pathogen spillover across ecosystem boundaries: mechanisms and theory. philosophical transactions of the royal society of london. series b, biological sciences, 374: 20180344. brancalion, p.h., broadbent, e.n., de-miguel, s., cardil, a., rosa, m.r., almeida, c.t., almeida, d.r., chakravarty, s., zhou, m., gamarra, j.g. and liang, j., 2020. emerging threats linking tropical deforestation and the covid-19 pandemic. perspectives in ecology and conservation, 18: 243-246. brearley, g., rhodes, j., bradley, a., baxter, g., seabrook, l., lunney, d., liu, y., and mcalpine, c., 2013. wildlife disease prevalence in human-modified landscapes. biological reviews of the cambridge philosophical society, 88: 427-442. buxton, r. t., bergman, j. n., lin, h. y., binley, a. d., avery-gomm, s., schuster, r., roche, d. g. and bennett, j. r., 2020. three lessons conservation science can learn from the covid-19 pandemic. conservation biology: the journal of the society for conservation biology, 34: 1331-1332. carlson, c. j., albery, g. f. and phelan, a., 2021. preparing international cooperation on pandemic prevention for the anthropocene. bmj global health, 6(3): 4254. ceballos, g., ehrlich, p. r. and raven, p. h., 2020. vertebrates on the brink as indicators of biological annihilation and the sixth mass extinction. proceedings of the national academy of sciences of the united states of america, 117: 13596-13602. chakraborty, i. and maity, p., 2020. covid-19 outbreak: migration, effects on society, global environment and prevention. the science of the total environment, 728: 138882. chin, a., simon, g. l., anthamatten, p., kelsey, k. c., crawford, b. r. and weaver, a. j., 2020. pandemics and the future of human-landscape interactions. anthropocene, 31: 100256. clark j. n., 2020. the covid-19 pandemic and ecological connectivity: implications for international criminal law and transitional justice. journal of international criminal justice, 057. 10 coccia m., 2020. factors determining the diffusion of covid-19 and suggested strategy to prevent future accelerated viral infectivity similar to covid. the science of the total environment, 729: 138474. cooke, s. j., cramp, r. l., madliger, c. l., bergman, j. n., reeve, c., rummer, j. l., hultine, k. r., fuller, a., french, s. s. and franklin, c. e., 2021. conservation physiology and the covid19 pandemic. conservation physiology, 9: 139. córdoba-aguilar, a., ibarra-cerdeña, c. n., castro-arellano, i. and suzan, g., 2021. tackling zoonoses in a crowded world: lessons to be learned from the covid-19 pandemic. acta tropica, 214: 105780. cunningham, a.a., daszak, p. and wood, j.l., 2017. one health, emerging infectious diseases and wildlife: two decades of progress. philosophical transactions of the royal society b: biological sciences, 372: 20160167. cutler, s. j., fooks, a. r. and van der poel, w. h., 2010. public health threat of new, reemerging and neglected zoonoses in the industrialized world. emerging infectious diseases, 16: 1-7. da silva, p. g., mesquita, j. r., de são josé nascimento, m. and ferreira, v., 2021. viral, host and environmental factors that favor anthropozoonotic spillover of coronaviruses: an opinionated review, focusing on sars-cov, mers-cov and sars-cov-2. the science of the total environment, 750: 141483. daniels, p. w., halpin, k., hyatt, a. and middleton, d., 2007. infection and disease in reservoir and spillover hosts: determinants of pathogen emergence. current topics in microbiology and immunology, 315: 113-131. daszak, p., das neves, c., amuasi, j., haymen, d., kuiken, t., roche, b., zambrana-torrelio, c., buss, p., dundarova, h., feferholtz, y., foldvari, g., igbinosa, e., junglen, s., liu, q., suzan, g., uhart, m., wannous, c., woolaston, k., mosig reidl, p., o'brien, k., pascual, u., stoett, p., li, h., ngo, h. t., 2020. workshop report on biodiversity and pandemics of the intergovernmental platform on biodiversity and ecosystem services. de garine-wichatitsky, m., binot, a., ward, j., caron, a., perrotton, a., ross, h., tran quoc, h., valls-fox, h., gordon, i. j., promburom, p., ancog, r., anthony kock, r., morand, s., chevalier, v., allen, w., phimpraphai, w., duboz, r. and echaubard, p., 2021. "health in" and "health of" social-ecological systems: a practical framework for the management of healthy and resilient agricultural and natural ecosystems. frontiers in public health, 8: 616328. delahay, r. j., de la fuente, j., smith, g. c., sharun, k., snary, e. l., flores girón, l., nziza, j., fooks, a. r., brookes, s. m., lean, f., breed, a. c. and gortazar, c., 2021. assessing the risks of sars-cov-2 in wildlife. one health outlook, 3: 7. dhama, k., patel, s. k., sharun, k., pathak, m., tiwari, r., yatoo, m. i., malik, y. s., sah, r., rabaan, a. a., panwar, p. k., singh, k. p., michalak, i., chaicumpa, w., martinez-pulgarin, d. f., bonilla-aldana, d. k. and rodriguez-morales, a. j., 2020. sars-cov-2 jumping the species barrier: zoonotic lessons from sars, mers and recent advances to combat this pandemic virus. travel medicine and infectious disease, 37: 101830. dirzo, r., young, h.s., galetti, m., ceballos, g., isaac, n.j. and collen, b., 2014. defaunation in the anthropocene. science, 345: 401-406. dunk, j. h., jones, d. s., capon, a. and anderson, w. h., 2019. human health on an ailing planet historical perspectives on our future. the new england journal of medicine, 381: 778-782. dykstra, m. p. and baitchman, e. j., 2021. a call for one health in medical education: how the covid19 pandemic underscores the need to integrate human, animal, and environmental health. academic medicine: journal of the association of american medical colleges, 96: 951-953. ellwanger, j. h. and chies, j., 2021. zoonotic spillover: understanding basic aspects for better prevention. genetics and molecular biology, 44: 20200355. ellwanger, j. h., kaminski, v. l. and chies, j., 2019. emerging infectious disease prevention: where should we invest our resources and efforts?. journal of infection and public health, 12: 313316. perera / journal of tropical forestry and environment vol. 11 no. 01 (2021) 1-15 11 everard, m., johnston, p., santillo, d. and staddon, c., 2020. the role of ecosystems in mitigation and management of covid-19 and other zoonoses. environmental science and policy, 111: 7-17. faust, c. l., mccallum, h. i., bloomfield, l., gottdenker, n. l., gillespie, t. r., torney, c. j., dobson, a. p. and plowright, r. k., 2018. pathogen spillover during land conversion. ecology letters, 21: 471-483. gibb, r., frankilnos, l., redding, d. and jones, k., 2020. ecosystem perspectives are needed to manage zoonotic risks under climate change. bmj: british medical journal. gibb, r., redding, d. w., chin, k. q., donnelly, c. a., blackburn, t. m., newbold, t. and jones, k. e., 2020. zoonotic host diversity increases in human-dominated ecosystems. nature, 584: 398402. glidden, c.k., nova, n., kain, m.p., lagerstrom, k.m., skinner, e.b., mandle, l., sokolow, s.h., plowright, r.k., dirzo, r., leo, g.a.d. and mordecai, e.a., 2021. impacts of anthropogenic change on biodiversity affects disease spillover risk. gottdenker, n. l., streicker, d. g., faust, c. l. and carroll, c. r., 2014. anthropogenic land use change and infectious diseases: a review of the evidence. ecohealth, 11: 619-632. grange, z.l., goldstein, t., johnson, c.k., anthony, s., gilardi, k., daszak, p., olival, k.j., o’rourke, t., murray, s., olson, s.h. and togami, e., 2021. ranking the risk of animal-tohuman spillover for newly discovered viruses. proceedings of the national academy of sciences, 118: 2002324118. guo, f., bonebrake, t. c. and gibson, l., 2019. landuse change alters host and vector communities and may elevate disease risk. ecohealth, 16: 647-658. harrison, m.e., wijedasa, l.s., cole, l.e., cheyne, s.m., choiruzzad, s.a.b., chua, l., dargie, g.c., ewango, c.e., coronado, e.n.h., ifo, s.a. and imron, m.a., 2020. tropical peatlands and their conservation are important in the context of covid-19 and potential future (zoonotic) disease pandemics. peerj, 8: 10283. hassell, j. m., begon, m., ward, m. j. and fèvre, e. m., 2017. urbanization and disease emergence: dynamics at the wildlife-livestock-human interface. trends in ecology and evolution, 32: 5567. johnson, c.n., balmford, a., brook, b.w., buettel, j.c., galetti, m., guangchun, l. and wilmshurst, j.m., 2017. biodiversity losses and conservation responses in the anthropocene. science, 356: 270-275. jones, b. a., betson, m., and pfeiffer, d. u., 2017. eco-social processes influencing infectious disease emergence and spread. parasitology, 144: 26-36. jones, k. e., patel, n. g., levy, m. a., storeygard, a., balk, d., gittleman, j. l. and daszak, p., 2008. global trends in emerging infectious diseases. nature, 451: 990-993. jowell, a. and barry, m., 2020. covid-19: a matter of planetary, not only national health. the american journal of tropical medicine and hygiene, 103: 31-32. karesh, w. b., cook, r. a., bennett, e. l. and newcomb, j., 2005. wildlife trade and global disease emergence. emerging infectious diseases, 11: 1000-1002. karesh, w. b., dobson, a., lloyd-smith, j. o., lubroth, j., dixon, m. a., bennett, m., aldrich, s., harrington, t., formenty, p., loh, e. h., machalaba, c. c., thomas, m. j. and heymann, d. l., 2012. ecology of zoonoses: natural and unnatural histories. lancet, london, england, 380: 1936-1945. keesing, f. and ostfeld, r. s., 2021. impacts of biodiversity and biodiversity loss on zoonotic diseases. proceedings of the national academy of sciences of the united states of america, 118: 2023540118. keesing, f., belden, l., daszak, p. dobson, a., c. drew harvell, c.d., holt, r.d., peter hudson, p., jolles, a., jones, k.e., mitchell, c.e., myers, s.s., bogich, t. and ostfeld r.s., 2010. impacts of biodiversity on the emergence and transmission of infectious diseases. nature, 468: 647652. 12 keesing, f., holt, r. d. and ostfeld, r. s., 2006. effects of species diversity on disease risk. ecology letters, 9: 485-498. kenyon c., 2020. emergence of zoonoses such as covid-19 reveals the need for health sciences to embrace an explicit eco-social conceptual framework of health and disease. epidemics, 33: 100410. khan, m., adil, s. f., alkhathlan, h. z., tahir, m. n., saif, s., khan, m. and khan, s. t., 2020. covid-19: a global challenge with old history, epidemiology and progress so far. molecules, basel, switzerland, 26: 39. khetan a. k., 2020. covid-19: why declining biodiversity puts us at greater risk for emerging infectious diseases, and what we can do. journal of general internal medicine, 35: 2746-2747. kilpatrick, a. m. and randolph, s. e., 2012. drivers, dynamics, and control of emerging vector-borne zoonotic diseases. lancet, london, england, 380: 1946-1955. kock r. a., 2013. will the damage be done before we feel the heat? infectious disease emergence and human response. animal health research reviews, 14: 127-132. konda, m., dodda, b., konala, v.m., naramala, s. and adapa, s., 2020. potential zoonotic origins of sars-cov-2 and insights for preventing future pandemics through one health approach. cureus, 12. kreuder johnson, c., hitchens, p. l., smiley evans, t., goldstein, t., thomas, k., clements, a., joly, d. o., wolfe, n. d., daszak, p., karesh, w. b. and mazet, j. k., 2015. spillover and pandemic properties of zoonotic viruses with high host plasticity. scientific reports, 5: 14830. lambin, e.f., tran, a., vanwambeke, s.o., linard, c. and soti, v., 2010. pathogenic landscapes: interactions between land, people, disease vectors, and their animal hosts. international journal of health geographics, 9: 1-13. lewis, s. l. and maslin, m. a., 2015. defining the anthropocene. nature, 519: 171-180. mackenzie, j. s. and jeggo, m., 2013. reservoirs and vectors of emerging viruses. current opinion in virology, 3: 170-179. marselle, m.r., hartig, t., cox, d.t., de bell, s., knapp, s., lindley, s., triguero-mas, m., böhninggaese, k., braubach, m., cook, p.a. and de vries, s., 2021. pathways linking biodiversity to human health: a conceptual framework. environment international, 150: 106420. maxmen a., 2021. who report into covid pandemic origins zeroes in on animal markets, not labs. nature, 592: 173-174. mcmahon, b.j., morand, s., and gray, j.s., 2018. ecosystem change and zoonoses in the anthropocene. zoonoses public health. 65:755-765. mcneely j. a., 2021. nature and covid-19: the pandemic, the environment, and the way ahead. ambio, 50: 767-781. mills, j. n., gage, k. l., and khan, a. s., 2010. potential influence of climate change on vector-borne and zoonotic diseases: a review and proposed research plan. environmental health perspectives, 118: 1507-1514. mishra, j., mishra, p. and arora, n. k., 2021. linkages between environmental issues and zoonotic diseases: with reference to covid-19 pandemic. environmental sustainability: 1-13. modonesi, c., 2020. the environmental roots of zoonotic diseases: from sars-cov-2 to cancer viruses. a review. visions for sustainability, 14:54-65. mohan, s. v., hemalatha, m., kopperi, h., ranjith, i. and kumar, a. k., 2021. sars-cov-2 in environmental perspective: occurrence, persistence, surveillance, inactivation and challenges. chemical engineering journal, lausanne, switzerland, 405:126893. morand s., 2020. emerging diseases, livestock expansion and biodiversity loss are positively related at global scale. biological conservation, 248: 108707. morand, s. and lajaunie, c., 2021. outbreaks of vector-borne and zoonotic diseases are associated with changes in forest cover and oil palm expansion at global scale. frontiers in veterinary science, 8: 661063. perera / journal of tropical forestry and environment vol. 11 no. 01 (2021) 1-15 13 morse, s. s., mazet, j. a., woolhouse, m., parrish, c. r., carroll, d., karesh, w. b., zambranatorrelio, c., lipkin, w. i. and daszak, p., 2012. prediction and prevention of the next pandemic zoonosis. lancet, london, england, 380: 1956-1965. murray, k. a. and daszak, p., 2013. human ecology in pathogenic landscapes: two hypotheses on how land use change drives viral emergence. current opinion in virology, 3: 79-83. nazir, r., ali, j., rasul, i., widemann, e. and shafiq, s., 2021. eco-environmental aspects of covid19 pandemic and potential control strategies. international journal of environmental research and public health, 18: 3488. o'callaghan-gordo, c. and antó, j. m., 2020. covid-19: the disease of the anthropocene. environmental research, 187: 109683. ostfeld r. s. 2017. biodiversity loss and the ecology of infectious disease. the lancet. planetary health, 1: 2-3. ostfeld, r.s., 2009. biodiversity loss and the rise of zoonotic pathogens. clinical microbiology and infection, 15: 40-43. pearce-duvet j. m., 2006. the origin of human pathogens: evaluating the role of agriculture and domestic animals in the evolution of human disease. biological reviews of the cambridge philosophical society, 81: 369-382. petrovan, s.o., aldridge, d.c., bartlett, h., bladon, a.j., booth, h., broad, s., broom, d.m., burgess, n.d., cleaveland, s., cunningham, a.a. and ferri, m., 2021. post covid‐19: a solution scan of options for preventing future zoonotic epidemics. biological reviews of the cambridge philosophical society. pfäffle, m., littwin, n. and petney, t., 2015. the relationship between biodiversity and disease transmission risk. research and reports in biodiversity studies. 4: 9-20. plowright, r. k., parrish, c. r., mccallum, h., hudson, p. j., ko, a. i., graham, a. l. and lloydsmith, j. o., 2017. pathways to zoonotic spillover. nature reviews microbiology, 15: 502510. plowright, r. k., reaser, j. k., locke, h., woodley, s. j., patz, j. a., becker, d. j., oppler, g., hudson, p. j. and tabor, g. m., 2021. land use-induced spillover: a call to action to safeguard environmental, animal, and human health. the lancet. planetary health, 5: 237-245. rahimi, n. r., fouladi-fard, r., aali, r., shahryari, a., rezaali, m., ghafouri, y., ghalhari, m. r., asadi-ghalhari, m., farzinnia, b., conti gea, o. and fiore, m., 2021. bidirectional association between covid-19 and the environment: a systematic review. environmental research, 194: 110692. rahman, m. t., sobur, m. a., islam, m. s., ievy, s., hossain, m. j., el zowalaty, m. e., rahman, a. t. and ashour, h. m., 2020. zoonotic diseases: etiology, impact, and control. microorganisms, 8: 1405. rhyan, j. c. and spraker, t. r., 2010. emergence of diseases from wildlife reservoirs. veterinary pathology, 47: 34-39. roche, b., dobson, a. p., guégan, j. f. and rohani, p., 2012. linking community and disease ecology: the impact of biodiversity on pathogen transmission. philosophical transactions of the royal society of london. series b, biological sciences, 367: 2807-2813. rubio, a. v., fredes, f. and simonetti, j. a., 2016. links between land-sharing, biodiversity, and zoonotic diseases: a knowledge gap. ecohealth, 13: 607-608. rulli, m.c., d’odorico, p., galli, n. and hayman, d.t.s., 2021. land-use change and the livestock revolution increase the risk of zoonotic coronavirus transmission from rhinolophid bats. nat food 2: 409-416. rutz, c., loretto, m. c., bates, a. e., davidson, s. c., duarte, c. m., jetz, w., johnson, m., kato, a., kays, r., mueller, t., primack, r. b., ropert-coudert, y., tucker, m. a., wikelski, m. and cagnacci, f., 2020. covid-19 lockdown allows researchers to quantify the effects of human activity on wildlife. nature ecology and evolution, 4: 1156-1159. 14 salian, v. s., wright, j. a., vedell, p. t., nair, s., li, c., kandimalla, m., tang, x., carmona porquera, e. m., kalari, k. r. and kandimalla, k. k., 2021. covid-19 transmission, current treatment, and future therapeutic strategies. molecular pharmaceutics, 18: 754-771. salkeld, d. j., padgett, k. a. and jones, j. h., 2013. a meta-analysis suggesting that the relationship between biodiversity and risk of zoonotic pathogen transmission is idiosyncratic. ecology letters, 16: 679-686. sánchez, c. a., venkatachalam-vaz, j. and drake, j. m., 2021. spillover of zoonotic pathogens: a review of reviews. zoonoses and public health. schmeller, d. s., courchamp, f. and killeen, g., 2020. biodiversity loss, emerging pathogens and human health risks. biodiversity and conservation: 1-8. schwartz, d., 2021. prioritizing the continuing global challenges to emerging and reemerging viral infections. frontiers in virology: 1-4. smith, k. f., goldberg, m., rosenthal, s., carlson, l., chen, j., chen, c. and ramachandran, s., 2014. global rise in human infectious disease outbreaks. journal of the royal society, interface, 11: 20140950. smith, k.f. and guégan, j.f., 2010. changing geographic distributions of human pathogens. annual review of ecology, evolution, and systematics: 41231-250. snedden, c. e., makanani, s. k., schwartz, s. t., gamble, a., blakey, r. v., borremans, b., helman, s. k., espericueta, l., valencia, a., endo, a., alfaro, m. e. and lloyd-smith, j. o., 2021. sars-cov-2: cross-scale insights from ecology and evolution. trends in microbiology, 29: 593-605. sokolow, s. h., nova, n., pepin, k. m., peel, a. j., pulliam, j., manlove, k., cross, p. c., becker, d. j., plowright, r. k., mccallum, h. and de leo, g. a., 2019. ecological interventions to prevent and manage zoonotic pathogen spillover. philosophical transactions of the royal society of london. series b, biological sciences, 374: 20180342. taylor, l. h., latham, s. m., and woolhouse, m. e., 2001. risk factors for human disease emergence. philosophical transactions of the royal society of london. series b, biological sciences, 356: 983-989. tollefson j. why deforestation and extinctions make pandemics more likely. nature. 2020 aug; 584:175-176. tollefson, j., 2020. why deforestation and extinctions make pandemics more likely. nature, 584: 175176. vandersmissen, a. and welburn, s. c., 2014. current initiatives in one health: consolidating the one health global network. revue scientifique et technique (international office of epizootics), 33: 421-432. watts, n., adger, w.n., ayeb-karlsson, s., bai, y., byass, p., campbell-lendrum, d., colbourn, t., cox, p., davies, m., depledge, m. and depoux, a., 2017. the lancet countdown: tracking progress on health and climate change. the lancet, 389: 1151-1164. weiss, r. a. and mcmichael, a. j., 2004. social and environmental risk factors in the emergence of infectious diseases. nature medicine, 10: 70-76 white, r.j. and razgour, o., 2020. emerging zoonotic diseases originating in mammals: a systematic review of effects of anthropogenic land‐use change. mammal review, 50: 336-352. who commission on health, environment and world health organization, 1992. report of the who commission on health and environment: summary. world health organization. wilkinson, d. a., marshall, j. c., french, n. p. and hayman, d., 2018. habitat fragmentation, biodiversity loss and the risk of novel infectious disease emergence. journal of the royal society, interface, 15: 20180403. woolhouse, m. e. and gowtage-sequeria, s., 2005. host range and emerging and reemerging pathogens. emerging infectious diseases, 11: 1842-1847. perera / journal of tropical forestry and environment vol. 11 no. 01 (2021) 1-15 15 world health organization and secretariat of the convention on biological diversity. (2012). connecting global priorities: biodiversity and human health a state of the knowledge review. geneva: who press world health organization, 2004. report of the who/fao/oie joint consultation on emerging zoonotic diseases in collaboration with the health council of the netherlands. world health organization. world health organization, 2005. ecosystems and human well-being: health synthesis: a report of the millennium ecosystem assessment/core writing team: carlos corvalan, simon hales, anthony mcmichael; extended writing team: colin bulter et al.;review editors: josé sarukhán et al., in ecosystems and human well-being: health synthesis: a report of the millennium ecosystem assessment/core writing team: carlos corvalan, simon hales, anthony mcmichael; extended writing team: colin bulter et al.; review editors: josé sarukhán et al. wu t., 2021. the socioeconomic and environmental drivers of the covid-19 pandemic: a review. ambio, 50: 822-833. zinsstag, j., utzinger, j., probst-hensch, n., shan, l. and zhou, x. n., 2020. towards integrated surveillance-response systems for the prevention of future pandemics. infectious diseases of poverty, 9: 140. zuluaga, s., speziale, k. and lambertucci, s. a., 2021. global aerial habitat conservation postcovid-19 anthropause. trends in ecology and evolution, 36: 273-277. muthumala et al. /journal of tropical forestry and environment vol. 9, no. 02 (2019) 55-64 _________________________________________ *correspondence: ck_muthumala@yahoo.com tel: +94777834716 issn 2235-9370 print/issn 2235-9362 online © university of sri jayewardenepura 55 identifying the strength grade for finger jointed timber species according to bs 5268-2:2002 c.k. muthumala1*, s. de silva2, k.k.i.u. arunakumara3 and p.l.a.g. alwis4 1research, development and training division, state timber corporation, battaramulla, sri lanka 2department. of civil and environmental engineering, faculty of engineering, university of ruhuna, hapugala, sri lanka 3department of crop science, faculty of agriculture, university of ruhuna, kamburupitiya, sri lanka 4department of agricultural engineering, faculty of agriculture, university of ruhuna, kamburupitiya, sri lanka date received 22-11-2018 date accepted 24-12-2019 abstract off-cut wood is currently considered as waste thus is dumped by saw mills as they find no means of utilising them. sawn timber material of furniture factories and short length of sawn timbers are also considered to be wastes in the timber industry. finger jointing technique which interlock the end joints formed by machining a number of similar tapered symmetrical fingers are recognised in this regards as effective and sustainable means of utilisation of timber wastes. the present study was undertaken to assess the strength grade of finger jointed timber based on bs 5268-2:2002. seven timber species which are commonly used in sri lanka were employed for the assessment with and without finger joints. values of modulus of rupture (mor), modulus of elasticity (moe), compression parallel to grain and compression perpendicular to grain strength of the specimens were measured. finger jointing was performed with constant geometry (finger length 19 mm, tip width 1 mm and finger pitch 4 mm) using polyvinyl acetate (pva, p-swr) adhesive at normal exposure conditions. the strength properties were evaluated by universal testing machine (utm) according to bs 373:1957. strength classes relevant to the grade stresses were not significant for finger jointed and clear specimens of satin, mahogany, jack and grandis. both clear and finger jointed timber specimens obtained d40 for satin and teak, d30 for jack, mahogany and grandis. teak shows properties similar to both d35 and d40 when used as finger jointed timber. kumbuk was shown to change from d40 to d30 while using as finger jointed timber. finger jointed pine showed stress grade of c22, c24 and c27. keywords: finger joint; grade stress, universal testing machine 1. introduction timber is considered to be one of the oldest building materials used in sri lanka. it is widely used as a structural element in the construction industries thus has a steadily increased demand. in sri lanka there are over 400 different timber species (muthumala and amarasekara, 2013). during the processing, a considerable portion of timber is removed as waste dumped by sawmills. dumping of timber as wastes and shorter sections is becoming a matter of great concern due to its scarcity. therefore, innovative means of timber utilisation in particular, making use of waste sawn timber planks receives high recognition (muthumala et al, 2018). a substantial portion of off-cut timbers in sri lanka is dumped as unused timber. no effective means has so far been found for the effective utilisation of off-cut timbers. even though, a doi: https://doi.org/10.31357/jtfe.v9i2.4468 56 number of woodworking joints is employed for the utilisation of large timber structural elements, use of small timber sections for structural purposes is yet to be explored. if the off-cut timber could be used for making such structural elements, timber wastage could substantially be minimised. finger joint is considered to be a sustainable, eco-friendly and economically viable technique which ensures sustainable utilisation of small timber planks (sandika et al, 2017). finger joints are described as interlocking end joints formed by machining a number of similar tapered symmetrical fingers at their ends using finger joint cutters and then binding together (bsi, bs en 15497, 2014). finger joints with off-cut timber may be useful in obtaining compression member with higher cross sections. as well as, production of timbers with high aesthetical value for different species is also ensured through this technique. the defects commonly found in the timbers could also be removed with this technique. even though the strength of finger jointed timber sections of softwoods has been evaluated extensively, little attention has so far been made on the hardwoods. however, most of the commonly used timber species in sri lanka are hardwoods. therefore, the technology required for making finger joints with hardwoods has been developed and made available for local u se. finger length of 19 mm and polyvinyl acetate swr adhesive was found to be the most suitable combination for making finger joints for local timber species (muthumala et al., 2018). furthermore the combination is recommended for the hardwoods and hardwood off -cuts which are used as structural components in the construction industry in sri la nka. in the future, fingerjointed material is certain to become more common place in both lumber and finished products as a means of upgrading defective material to clear and in creating otherwise unavailable long lengths (hoadley, 2000). despite the fact that the structural performance of the finger jointed timber products such as studs, trusses, columns, beams etc., has been investigated the connections properties of finger joints have been investigated thus not included in the british standards (bs) design code. therefor the main objective of this study is to assess the strength grade of finger jointed timber based on bs 5268-2:2002. which provides with necessary guidance on the structural use of timber, glued laminated timber, plywood, tempered hardboard and wood particle boards in load bearing members. it includes the recommendations on the quality, grade stresses and modification factors applicable to these materials when they are used as simple members, or as parts of built-up components, or as parts of structural components with the incorporation of other materials. in literature, strength evaluation of finger jointed sections has been mainly found to be concentrated on temperate species (fisette and rice 1988, samson 1985). as far as hardwoods are concerned, there are some reports from ghana (ayarkwa et al. 2000). a recent report from india tries to explain the measured flexural parameters of eucalyptus in terms of the joint areas (kumar et al. 2013). 2. methodology 2.1 sample collection six timber species namely; grandis (eucalyptus grandis), jack (aartocarpus heterphyllus), kumbuk (terminelia arjuna), mahogany (swietenia macrophylla), satin (chloroxylon swietenia) and teak (tectona grandis), were selected as hardwoods and pine (pinus caribaea), was selected as softwood considering their very high usage in sri lanka. timber materials labelled as wastes were collected from the state timber corporation (stc) saw mill at boossa, sri lanka and used for the muthumala et al. /journal of tropical forestry and environment vol. 9, no. 02 (2019) 55-64 57 study. the timber sections were selected from visually inspected defects free portions before been further treatments. 2.2 specimen preparation specimens were prepared using seasoned (m.c. 12%) timber planks according to bs standards (bs 373:1957 and bs en 15497:2014). ten clear timber specimens were used as control specimens and 10 finger jointed timber specimens with same dimensions were made with constant finger geometry (finger length19 mm, tip width 1 mm and finger pitch 4 mm) as shown in figure 1. specimens of clear and finger jointed were prepared from two timber planks with five replicates each. figure 1. finger geometry of a finger joint. finger jointing was performed on mid span, polyvinyl acetateswr adhesive was used for gluing at normal exposure conditions (vievek et al, 2016). specimens were prepared at the furniture factory of the state timber corporation, boossa, galle, sri lanka. 2.3 specimen for three-point bending test (mor and moe) the off-cut woods were dried using a kiln drier to ensure the wood moisture content is below 12%. the average moisture content of wood materials was determined using a moisture meter before the preparation of test specimens. the samples were tested based on b.s. 373:1957 standards. 2.4 finger joint preparation the specimens with the dimension of 300 mm×25 mm×25 mm (moisture content of 12%) were cross cut into two pieces using a circular saw and used for the static bending tests (the length of a piece was 160 mm). the specimens with the dimension of 60 mm×20 mm×20 mm were cross cut into two pieces using the same saw machine and used for the compression test-parallel to grains. another set of specimen with the dimension of 50 mm×50 mm×50 mm were cross cut into two pieces and used for the compression test-perpendicular to grains (bs 373: 1957). 2.5 experimental procedure sample testing was performed at the laboratory of stc, battaramulla, colombo, sri lanka. three-point bending test and compression tests of the prepared specimens were conducted using universal testing machine (utm) (give the type/brand, country of produced etc) according to bs 373:1957. before loading by utm, the average density and natural moisture content were measured for each species. 2.6 average density the timber samples were placed in an oven at 105o c for 48 hours and the dry weight was measured. the density values were calculated for the seven timber species using equation 1). (bs en 373:1957). 58 density = weight of oven dry wood (kg) volume of wood (m3) determination of basic density was done based on the green volume and oven-dry weight using a water displacement method. samples placed at room temperature showed good structural performance compared to those placed at hot and wet conditioned (give details) as demonstrated by vievek et al, (2016). 2.7 bending test specimens were tested by three-point bending test to obtain bending strength. the span was 280 mm for the test and load was applied on mid span of the specimen at a loading speed of 6 mm/min. displacement was recorded with the applied load and load vs displacement graph was plotted. modulus of rupture (mor) was calculated for the ultimate state using load vs displacement graph. maximum load represented the ultimate load and the maximum load in elastic region represented the serviceability load. when the applied load is the ultimate load, bending strength is taken as modulus of rupture. 2.8 modulus of elasticity (moe) modulus of elasticity is considered to be an indicator for stiffness of the wood and only applies to the conditions within the elastic limit. it i s the ratio of stress per unit area to the deformation per unit length. flexural test resulted at serviceability state was used to obtain the moe in this study. 2.9 compression parallel to grain test compression parallel to grain test was carried out with loading plate moving speed of 0.5 mm min-1 and load vs. displacement variation was obtained. compressive strength of clear timber at ultimate state was calculated by the maximum load acting on the timber before the failure which was obtained from the load deflection curve of compression parallel to grain test. maximum load of the elastic limit was used to obtain the serviceability state compressive strength. 2.10 compression perpendicular to grain test failure of the specimens was determined by loading them perpendicular to grain with loading plate moving speed of 0.5 mm min-1. displacement was obtained with the load applied and load vs. displacement curve was plotted. the maximum load identified with the graph was used to calculate ultimate compressive strength and the maximum load of the elastic region was used to calculate serviceability compressive strength perpendicular to grain. 2.11 strength class identification from bs 5268-2:2002 strength classes appeared in bs 5268-2:2002 are relevant to the grade stresses of timber at serviceability state. therefore, the characteristic strength obtained from the bending and compression test were employed to derive grade stresses. 2.12 grade stress-bending characteristic bending strength was calculated by the following factors to derive grade bending stresses. according to bs5268-2; section depth less than 72 mm-0.856, duration of the load very short term-0.571 grade stress=strength in serviceability limit state (n mm-2 )×0.856×0.571 (2) (1) muthumala et al. /journal of tropical forestry and environment vol. 9, no. 02 (2019) 55-64 59 3. results as shown in table 1, the average density values varied with the species and ranged between 440980 kg m-³. the highest average density value shows in satin timber species and the least average density value shows in pine timber species. table 1: average density and timber class of selected timber species. according to bs 373:1957, the average moisture content of the specimen should approximately be 12% at normal exposure conditions for testing. as depicted in table 2, the moisture contents varied within 9.38-13.83% thus, declared a suitable timber specimens for testing. table 2: average moisture content of tested specimen. table 3 shows that the characteristic bending strength reduction is less for satin and it is 9.5% compared to clear timber. teak and pine also have strength reduction % less than 20%. higher strength reduction % is shows in kumbuk timber species. table 3: average serviceability bending strength of tested specimen. according to table 4 moe for clear timber and finger jointed timber are approximately same and pine (soft wood) shows moe increment and other species have moe reduction less than 20%. the highest moe reduction % is shows in kumbuk timber species. species average density (kg m ³) timber class according to stc classification teak 740 super luxury satin 980 luxury mahogany 560 luxury jack 640 luxury kumbuk 720 special class grandis 550 class ii pine 440 class iii species specimen used for bending test (%) specimen used for compression parallel to grain test (%) specimen used for compression perpendicular to grain test (%) clear fj clear fj clear fj teak 10.50 10.28 10.63 10.58 9.98 10.05 satin 12.13 12.60 11.15 11.10 10.55 10.50 mahogany 10.85 10.88 10.35 10.33 9.68 10.03 jack 12.33 12.50 9.38 9.58 10.70 10.65 kumbuk 11.53 11.15 11.30 12.18 13.83 13.30 grandis 13.50 13.35 11.35 11.65 12.45 12.10 pine 11.35 11.38 11.15 11.60 10.43 10.40 species clear timber section (n mm -2 ) finger jointed timber section (n mm -2 ) strength reduction percentage % teak 26.02 23.20 10.84 satin 27.94 25.28 9.50 mahogany 24.59 16.64 32.34 jack 30.58 17.49 42.82 kumbuk 25.77 13.26 48.54 grandis 29.39 16.09 45.25 pine 20.86 16.80 19.43 60 table 4: average moe for tested specimens. serviceability compressive strength parallel to grain of jack is almost similar for clear and finger jointed timber according to table 5. satin, mahogany, grandis and pine also have strength reduction less than 20% at serviceability state. the highest average compressive strength parallel to grain reduction % is shows in kumbuk timber species. table 5: average compressive strength parallel to grain for tested specimens at serviceability state. species clear timber section (n mm -2 ) finger jointed timber section (n mm -2 ) strength reduction percentage % teak 24.45 18.20 25.54 satin 42.21 36.62 13.24 mahogany 15.62 13.51 13.51 jack 14.93 14.70 1.53 kumbuk 29.53 20.17 31.68 grandis 15.61 13.55 13.22 pine 15.89 15.40 3.04 table 6 depicts that compression perpendicular to grain test significantly different from bending and compression test results because finger jointed timber strengths have been increased for all the specimens other than jack compared to clear timber. table 6: average compressive strength perpendicular to grain for tested specimens at serviceability state. grade stress values of table 7 were calculated by bending strength in serviceability state×0.856×0.571. species clear timber specimen (n mm-2) finger jointed timber specimen (n mm-2) moe reduction percentage% teak 8865.07 8796.66 0.77 satin 9703.65 9493.32 2.17 mahogany 6208.59 5552.56 10.57 jack 5537.37 5391.96 2.63 kumbuk 5225.88 4383.83 16.11 grandis 5375.64 5286.38 1.66 pine 5361.99 6657.08 -24.15 species clear timber section (n mm -2 ) finger jointed timber section (n mm -2 ) strength reduction % teak 8.53 10.08 -18.13 satin 15.51 17.16 -10.66 mahogany 7.85 8.13 -3.66 jack 13.43 11.03 17.90 kumbuk 7.71 8.28 -7.31 grandis 5.14 5.38 -4.72 pine 6.06 7.72 -27.39 muthumala et al. /journal of tropical forestry and environment vol. 9, no. 02 (2019) 55-64 61 table 7: grade bending stresses for clear and finger jointed specimens. in table 8, average grade stresses for compression parallel to grain values were obtained according to bs 5268-2, considering very short term for the duration of the load characteristic strength should be multiplied by 0.571. table 8: average grade stresses for compression parallel to grain test. in table 9, average grade stresses for compression perpendicular to grain values were obtained according to bs 5268-2, considering very short term for the duration of the load characteristic strength should be multiplied by 0.571. table 9: average grade stresses for compression perpendicular to grain test. table 10 and table 11 show that grade stress values are derived using lower and higher values of bs 5268-2:2002.according to the calculation in table 10 and 11, strength classes are included in table 12. species clear timber section (n mm -2 ) finger jointed timber section (n mm -2 ) teak 12.71 11.33 satin 13.64 12.35 mahogany 12.01 8.13 jack 14.94 8.54 kumbuk 12.59 6.48 grandis 14.35 7.86 pine 10.19 8.21 species clear timber specimen (n/mm 2 ) finger jointed timber specimen (n/mm 2 ) teak 13.97 10.40 satin 24.12 20.93 mahogany 8.93 7.72 jack 8.53 8.40 kumbuk 16.87 11.53 grandis 8.92 7.74 pine 9.08 8.80 species clear timber specimen (n mm -2 ) finger jointed timber specimen (n mm -2 ) teak 4.88 5.76 satin 8.86 9.80 mahogany 4.48 4.65 jack 7.67 6.30 kumbuk 4.41 4.73 grandis 2.94 3.07 pine 3.46 4.41 62 table 10: grade strength comparison for clear timber according to bs 5268-2:2002. table 11: grade strength comparison for finger jointed timber according to bs 5268-2:2002. muthumala et al. /journal of tropical forestry and environment vol. 9, no. 02 (2019) 55-64 63 table 12: strength class identified. 3.1 strength class for clear and finger jointed timber strength class for selected timber species were obtained considering the average density, moe and grade stresses included in table 7, table 8 and table 9 which were obtained as experiment results. in this case, bs 5268-2:2002 was used and strength class for clear and finger jointed timber were obtained separately. nearest higher and lower value for the test resulted value were obtained from bs 5268-2:2002 and considering the minimum deviation for grade stress which were obtained from test strength class were selected. deviation was calculated as a percentage by using equation 3. deviation = grade stress obtain as experiment results − nearest grade stress grade stress obtain as experiment results ×100% 4. discussion according to the bsi standardbs 5268:2002, ''grade stresses for tropical hardwoods graded in accordance with bs 5756 rules for service classes 1 and 2'', teak clear timber shows grade stresses for bending-13.7 (n/mm2), compression parallel to grain-13.4 (n mm-2), compression perpendicular to grain-3.1(n mm-2)and moe7400 (n mm-2). in experimental results values are also closely similar to the standard values as bending12.71 (n mm-2), compression parallel to grain-13.97 (n mm-2), compression perpendicular to grain-4.88 (n mm-2) and moe8865 (n mm-2). so, accuracy of the experimental values are acceptable. according to table 12, considering finger jointed timber, teak shows similar to both d35 and d40. finger jointed satin, mahogany, jack and grandis timber are almost similar to clear timber in this case. kumbuk has been changed from d40 to d30 while use as finger jointed timber. (d represent-hard wood and c represent-soft wood). pine clear timber shows c27 and finger jointed pine shows c22, c24 or c27. all the clear specimens and finger jointed specimens except kumbuk, show nearly similar grade stress classes. thus, this finger joint technology can be used for producing elements. 5. conclusion finger joint technique is used locally for manufacturing process in sri lanka considering the mechanical properties. therefore, the reliability of finger joint as an alternative method of connecting timber structural elements needed to be evaluated. the performance of finger jointed standard specimens and the strength grade of them were studied based on bs 5268-2:2002. no significant differences in strength classes relevant to the grade stresses were observed for finger jointed and clear specimens for satin, mahogany, jack and grandis. both clear and finger jointed timber species category clear timber finger jointed timber teak hardwood d40 d35/d40 satin hard wood d40/d70 d40/d70 mahogany hard wood d30 d30 jack hard wood d30 d30 kumbuk hard wood d40 d30 grandis hard wood d30 d30 pine soft wood c27 c22/24/27 (3) 64 specimens obtained d40 for satin and teak, d30 for jack, mahogany and grandis. teak showed similar properties to both d35 and d40 when it was used as finger jointed timber. grade stress class was changed in kumbuk species from d40 to d30 while it was used as finger jointed timber. finger jointed pine showed properties of c22, c24 and c27. the present findings proved that finger joint technique is useful in effective utilization of off-cut timbers to manufacture finger jointed structural and non-structural elements. acknowledgment authors thank to laboratory staff of the state timber corporation for their valuable assistants in research works. references ayarkwa, j., hirashima, y. and sasaki, y., 2000. effect of finger geometry and end pressure on the flexural properties of finger-jointed tropical african hardwoods. forest products journal, 50:53-63. british standard institution, 1999. bs 373: 1957. methods of testing small clear specimens of timber. british standards institution. london. british standard institution, 2014. bs en 15497:2014, structural finger jointed solid timber-performance requirements and minimum production requirements. european committee for standardisation. b 1000 brussels. british standard institution, 1996. bs en 5268-2: 2002, structural use of timber-code of practise for permissible stress design, materials and workmanship. bsi. chiswick high road. london. fisette, p.r. and rice, w.w., 1988. an analysis of structural finger-joints made from two north eastern species. forest products journal, 38:40-44 hoadley, r.b., 2000. understanding wood: a craftsman’s guide to wood technology, chapter 16, the taunton press, usa. 241 kumar, k., sharma, v.s. and gupta, c.m., 2013. role of fingertip area on flexural strength properties of finger-jointed sections. international wood products journal, 4:101-106. muthumala, c.k. and amarasekara, h.s., 2013. investigation the authenticity of local and imported timber species in sri lanka, proceeding of the international forestry and environment symposium, department of forestry and environmental science, university of sri jayewardenepura, 95. muthumala, c.k., de siva, s. alwis, p.l.a.g. and aruna kumara, k.k.i.u., 2018. factors affecting the glue strength of finger-joints in commonly used timber species in sri lanka. international symposium on agriculture and extension. faculty of agriculture. university of ruhuna, sri lanka, 126-128. muthumala, c.k., de silva, s., alwis, p.l.a.g. and arunakumara, k.k.i.u. investigate the most suitable glue type for finger-joints production in sri lanka. research journal of agriculture and forestry sciences, november, 2018. isca, india. 6:6-9. samson, m., 1985. potential of finger-jointed lumber for machine stress-rated lumber grades. forest products journal, 35:20-24. sandika, a.l., pathirana, g.d.p.s. and muthumala, c.k., 2017. finger joint timber products for effective utilisation of natural resources: an analysis of physical properties. economic factors and consumers’ perception. international symposium on agriculture and environment, university of ruhuna, sri lanka. 109-111. vievek, s., de silva, s., de silva, s. and muthumala, c.k., 2016. finger joint and their structural performance in different exposure conditions. 7th international conference on sustainable build environment. kandy. sri lanka, 207-210. adikaram and pitawala/journal of tropical forestry and environment vol. 7, no. 02 (2017) 1-9 1 feature article an overview of heavy metal contamination in coastal sediments of sri lanka a.m.n.m. adikaram1*and h.m.t.g.a. pitawala2 1department of physical sciences, faculty of applied sciences, south eastern university, sri lanka 2department of geology, faculty of science, university of peradeniya, sri lanka abstract coastal sediments are often subjected to heavy metal contamination as they reside at the marginal environments of anthropological water releases. these sediments provide the habitat for marine aquatic life of seafood. therefore, heavy metal contamination in coastal sediments is one of the major environmental concerns. the coastal belt of sri lanka is highly urbanized with high population (59% of sri lankan population) and is mostly depend on the sea. therefore, anthropogenic inputs of pollutants in to the marine environments have been increased during last decades. heavy metal contamination of the coastal sediments of sri lanka has been discussed by several studies, focusing on selected coastal regions. in this article, previous studies have been reviewed in order to understand the contamination status and ecological risks due to heavy metal accumulations.despite the sampling location, the elemental distribution of coastal lagoonalsediments shows similar trend indicating the dominance of natural elemental sources rather the anthropogenic influences. the concentrations of as and cr in sediments are high compared to the upper continental crust values which is a characteristic feature in possible source rocks, soils and sediments of sri lanka. theresults of the previous studies indicate thatcoastal sediments are low to moderately contaminated but notat ecological risk. however, anthropogenic activities are highly variable across the coastal regions. since limited results of the previous studies is not enough to get an overview of the heavy metal concentrationsaround the island, urgent need for a spatial and temporal geochemical database for coastal sediments of sri lanka is emphasized. keywords: contamination, coastal, metals and sediments 1. introduction environmental contaminants are in three categories:(a) stable trace elements (b) organic substances and (c) radionuclides (tornero andd'alcalà, 2014). united states environmental protection agency (usepa) has chosen the following trace elements including heavy metalssuch as ag, as, ba, be, cd, co, cr, cu, hg, mn, mo, ni, pb, sb, se and zn that is toxic in desired excessive concentrations. the list has expanded later by several authors (mcbridge, 1995; chen and ma, 1998). *correspondence: maduryaa@gmail.com tel: +94718318140 issn 2235-9370 print/issn 2235-9362 online © university of sri jayewardenepura 2 when a substance is above the level of background it is said to be as “contaminated”.when it is adversely affected on biological communities, it is said to be as“polluted” (chapman, 2007). heavy metal contamination in natural environments is a severe environmental problem due to their natural toxicity, persistence, vast sources and non-degradability (wang et al., 2013). heavy metals get into natural environments from effluents of industries, agriculture and aquaculture practices, and municipal and domestic wastes (tornero andd'alcalà, 2014). marineand coastal environments have been paid more attention because they are the ultimate settings of heavy metal accumulationsand human concern for seafood (wang et al., 2005).bioaccumulation, bio-magnification by food chains, destruction to organisms and ecological systems and consequently damage to ecological goods and services are the adverse effects of heavy metal contaminations (newton et al., 2013; tornero andd'alcalà, 2014). therefore, it is essential to monitor the present contamination status in marine and coastal environments. sri lankan coastline is about 1,920 km long and encompasses about 50% of the bay of bengal (katupotha, 1989).different coastal features such as lagoons, estuaries, sediment bars and spits, dunes, wave cuts, arches and cliffs which are characterized by erosional and depositional processes are presentaround the island (katupotha, 2007). the origin and evolution of coastal landforms of the country was activated during the quaternary period and the sea level reaches its present status about 3000 year bp (ranasinghe et al., 2013). several studies on different coastal landforms of sri lanka have been reviewed in this article to summarize the current status of coastal sediment contamination.this article reviews the existing literature on the concentrations of selected trace elements in the coastal regions of sri lanka and risk of contamination of the coastal ecosystems by them. 2. coastal environment of sri lanka the climate of sri lanka is tropical with diversified rainfalls from both southwest (sw) and northeast (ne) monsoons. in general, high rainfall is recorded during may to september due to sw monsoons and low rainfall during november to february due to ne monsoons. altogether 103 main rivers are flowing to the coastal low lands from the central part of the country. the river discharges are timely changed with monsoonal rainfall effect. huge sediment loads are carried through the river channels, and hence river channels are the basic sediment supplier for the coastal zones. large scale storm or cyclone has not been recorded during past decades except the tsunami occurred in 2004. the temperature ranges from 16° c to 32°c across the country. the lowest temperature recorded in the central highlands and highest temperatures are recorded in constantly southeastern and eastern coastal areas. the tidal effect of the island is micro-scale and hence no considerable effect on sedimentation in coastal zones except the regionally developing sea currents. many of the coastal zones of sri lanka are densely populated due to clear and shallow beaches, corals and hot sun. about 59% of the total population of sri lanka is associated to the coastal regions (nayanananda, 2007). most of the industrialized capital cities are located around the coastal margins of the country. sea around the country receives nutrient rich currents, therefore other than point sources of contaminants non-point source such as storm water and dust can contribute for contamination. fishing industry is famous in sri lanka and fish processing units are established around the coastal areas.western and southern coastal regions arehighly industrialized and densely populated. thus,effluents that comes from industries such as petroleum refining, ship repairing, tires and thermal industries other than the huge municipal and domestic leachates are mixed with natural waters are ended up at the sea.additionally, minor water based industries such as foundry, laundry, tannery, paper industries, service stations and “batik”fabric die work are commonly observed in coastal low lands of sri lanka where tourists are attracted. adikaram and pitawala/journal of tropical forestry and environment vol. 7, no. 02 (2017) 1-9 3 3. levels of contaminants in presentarticle, heavy metals and as concentrations in sediments ofseven main semi-enclosed marginal marine water bodiesand capital city of sri lanka are summarized from published data. these recent publications are done by collecting surface sediment fractions of each semi-enclosed body. sampling locations aretrincomalee bay, batticaloa lagoon, hambanthota lagoon, galle harbor, hikkaduwa lagoon, beruwala harbor, muthurajawela peat deposit and surface sediments of colombo city (dissanayake, 1987; jayawardana et al., 2012; young et al., 2014; silva, 2015; heath et al., 2016; adikaram et al., 2017).geographical distribution of the concentrations of the selected heavy metals of sri lanka is shown in figure 1 (dissanayake, 1987; jayawardana et al., 2012; young et al., 2014; silva, 2015; heath et al., 2016; adikaram et al., 2017).concentrations of zn and cr are significant in all natural lagoonal systems including muthurajawela peat deposit with compared to the other elements. the two harbors show high pb concentrations. substantial enrichments of zn and cu are observed in the city sediments of the colombo region. figure 1: geographical distribution of heavy metal concentrations in coastal sediments of sri lanka.(after dissanayake, 1987; jayawardana et al., 2012; young et al., 2014; silva, 2015; herath et al., 2016; adikaram et al., 2017). average concentrations of as, pb, zn, cu, ni and cr of the semi-enclosed water bodies of sri lanka, other published data in different regions of the world and international standards are summarized in table1. it is noted that the sediments of sri lankan coastal zones are not contaminated with compared to other compared marine environments of the world. 4 table 1: concentrations of heavy metals and as in coastal sediments of sri lanka and comparison with other coasts. country location concentration (ppm) as pb zn cu ni cr sri lanka batticaloa lagoon 5 (3-10)* 21 (14-26) 87 (21-155) 34 (6-216) 18 (7-41) 93 (52-146) adikaram et al., 2017 trincomalee, inner harbour 7 (3-19) 23 (3-103) 49 (21-152) 13 (2-41) 16 (3-57) 73 (26-192) young et al., 2014 trincomalee, thambalagam bay 10 (2-43) 14 (8-20) 31 (9-79) 6 (0-23) 11 (4-46) 50 (11-181) young et al., 2014 trincomalee, koddiyar bay 4 (2-9) 15 (9-20) 51 (6-181) 6 (2-14) 13 (0-27) 96 (7-356) young et al., 2014 hikkaduwa lagoon 7 (3-11) 13 (8-17) 35 (8-55) 6 (2-9) 8 (0-20) 60 (45-84) jayawardana et al., 2012 hambanthota lagoon 3 (3-4) 14 (14-15) 47 (38-72) 9 (5-12) 11 (10-17) 72 (61-78) jayawardana et al., 2012 galle fishery harbour nd 74 (61-87) 16 (1-68) 10 (7-16) nd nd silva (2015) beruwala fishery harbour nd 80 (37-102) 12 (0-50) 11 (5-15) nd nd silva (2015) muthurajawela peat nd nd 67 (26-262) 20 (12-37) nd 41 (20-84) dissanayake (1987) colombo city dust nd 26 (0-76) 270 (53625) 91 (28319) nd 80 (47-152) herath et al., (2016) india gulf of mannar nd 16 73 57 24 177 jonathan et al.,2009 kalpakkam nd 22 119 nd 53 118 selvaraj et al., 2004 pondicherry nd 33 52 48 20 334 solali et al, 2013 gange's estuary nd 29 71 26 32 67 subramanian et al., 1988 krishna estuary nd 4 1482 59 149 174 ramesh and subramanium, 1988 west bengal nd 17 74 36 34 37 sarkar et al., 2004 bangladesh chittagong coast, nd 18 355 189 33 658 hasan et al., 2013 tunisia mediterrnian sea (13-36) (65-152) (47-546) (8-29) (9-31) nd zohra and habib, 2016 china bhohai bay nd (21-66) (55-457) (20-63) (23-53) (60-224) gao and chen, 2012 sqg tec 10 36 121 32 23 43 mcdonald et al., 1996 pec 33 128 459 149 49 111 mcdonald et al., 1997 sqg: sediment quality guidelines, tec: threshold effect level, pec: probable effect level adikaram and pitawala/journal of tropical forestry and environment vol. 7, no. 02 (2017) 1-9 5 the concentration of as and cr in coastal sediments of sri lanka is high with compared to the upper continental crust (ucc) values (figure. 1; taylor and mclennan, 1985). the possible source country rock types are characterized in high concentrations of as and cr and this might be the reason for the enrichments of such elements (young et al., 2014). figure 2: ucc normalized elemental concentrations in coastal sediments of sri lanka (after dissanayake, 1987; jayawardana et al., 2012; young et al., 2014; silva, 2015; heath et al., 2016; adikaram et al., 2017). 4. environmental and ecological risk assessment of coastal sediments average concentrations of six trace elements of coastal sediments of sri lanka are compared with reference values of threshold effect concentration (tec) and probable effect concentrations (pec) of consensus-based freshwater ecosystem sediment quality guidelines (table 1; macdonald et al., 1996). values in between tec and pec are rarely or occasionally make adverse effects on organisms whereas values above pec make adverse effects on a wide range of organisms (macdonald et al., 1996). the average concentrations of as of sri lankan coasts are below the threshold values of sediment quality guidelines. in addition, beruwala and galle harbors shows above pbvalues for tec. the concentrations of zn, cu and cr of colombo city sediments show higher values for tec. except muthurajawela peaty sediments, all sediment types have exceeded the tec values for cr. however, average concentrations of all sediment types of sri lankan coasts are below the pec values suggesting the level of contamination is not much considerable. contamination factor (cf) is an elemental ratio of concentration of each metal in the sediment with concentration of those particular metals in the background (hakanson, 1980). the contamination levels may be classified based on their intensities on a scale ranging from 1 to 6 (0=none, 1=none to medium, 2 6 =moderate, 3=moderately to strong, 4=strongly polluted, 5=strong to very strong, 6=very strong (muller, 1969). 𝐶𝐹 = 𝐶𝑀𝑆𝑒𝑑𝑖𝑚𝑒𝑛𝑡 𝐶𝑀𝑏𝑎𝑐𝑘𝑔𝑟𝑜𝑢𝑛𝑑 (1) where: cm= metal concentration. the pollution load index (pli) is calculated using the cf values that provide comparative means to measure the level of pollution in different locations (tomlinson et al., 1980). 𝑃𝐿𝐼 = √𝐶𝐹1𝑥 𝐶𝐹2𝑥 𝐶𝐹3𝑥 … . 𝑥𝐶𝐹𝑛 𝑛 (2) where: cf =contamination factor and n is the number of elements. if sediments are polluted pli > 1 and for non-polluted pli<1 (tomlinson et al., 1980). the cf values and pli values for average concentrations of semi-enclosed coastal bodies of sri lanka are given in table 2. contamination factor also indicates enrichments of as and cr in sri lanka coasts. according to the pli values, colombo city sediments are significantly polluted. additionally,batticaloa lagoon and trincomalee bay shows slightly polluted sediments whereas other locations are unpolluted with the global references. this is basically due to the high concentrations of cr and as which is controlled by the country rocks. table 2: contamination factor, pollution load index and potential ecological risk index of coastal sediments, sri lanka. location contamination factor pli peri as pb zn cu ni cr batticaloa lagoon 3.3 1.1 1.2 1.4 0.9 2.7 1.6 56 trincomalee bay 3.3 1.1 1.2 1.4 0.9 2.7 1.6 56 hikkaduwa lagoon 4.7 0.7 0.5 0.2 0.4 1.7 0.8 57 hambanthota lagoon 2.0 0.7 0.7 0.4 0.6 2.1 0.9 33 galle harbour nd 3.7 0.2 0.4 nd nd 0.7 21 beruwalaharbour nd 4.0 0.2 0.4 nd nd 0.7 22 muthurajawela peat nd nd 0.9 0.8 nd 1.2 1.0 7 colombo city nd 1.3 3.8 3.6 nd 2.3 2.5 33 pli: pollution load index peri: potential ecological risk index adikaram and pitawala/journal of tropical forestry and environment vol. 7, no. 02 (2017) 1-9 7 high metal concentrations in sediments create adverse biological effects which can be measured by several defined approaches. to evaluate the adverse biological effect a simple method introduced by hakanson (1980) was used. the potential ecological risk index (peri) is specially proposed to assess the contamination levels of coastal sediments with respect to toxicity of some selected contaminants (hakanson, 1980). 𝑃𝐸𝑅𝐼 = ∑ 𝐸𝑟 (3) 𝐸𝑟 = 𝑇𝑟 𝑥 𝐶𝐹 (4) where: er= ecological risk factor tr= toxic response factor cf= contamination factor the standard values for tr are as, pb, zn, cu, ni and cr are 10, 5, 1, 5, 5 and 2 respectively. the peri < 90 is low potential ecological risk; 90 < peri < 190 is moderate ecological risk; 190 < peri < 380 is considerable ecological risk and peri > 380 is a very high ecological risk. according to the calculated peri values with published data, it can be suggested that the sri lankan coastal sediments have low potential ecological risk (table 2). 5. summery in summary, based on the available data of sri lankan coastal sediments, it can be concluded that the sediments are slightly polluted and that level is not adversely affected to the ecological systems. the selection of geochemical background values in contamination status evaluations might be a reason for the pollution status of the present article which is basically depends on the possible source rocks. regional trace metal concentrations are affected by the rock types, geomorphological conditions and geographical locations which are altered by physical and chemical weathering processes. therefore, to determine the anthropogenic influences more accurately, a baseline for the sediment trace metal concentrations should be determined regionally. this will help to identify the anthropogenic causes of pollution and take necessary actions to control pollution to prevent the present coastal sediments. references adikaram, m., pitawala, a., ishiga, h., jayawardana, d., (2017). spatial distribution, enrichment, and source of environmentally important elements in batticaloa lagoon, sri lanka. environmental science and pollution research 24(2), 2089-2099. chapman, p. m. (2007). determining when contamination is pollution—weight of evidence determinations for sediments and effluents. environment international 33(4), 492-501. chen, m., ma, l. q., (1998). comparison of four usepa digestion methods for trace metal analysis using certified and florida soils. journal of environmental quality 27(6), 1294-1300. gao, x., chen, c. t. a. (2012). heavy metal pollution status in surface sediments of the coastal bohai bay. water research 46(6), 1901-1911. hakanson, l., (1980). an ecological risk index for aquatic pollution control. a sedimentological approach. water research 14, 975–1001. 8 hasan, a.b., kabir, s., selim reza, a.h.m., zaman, m.n., ahsan, a., rashid, m., (2013). enrichment factor and geo-accumulation index of trace metals in sediments of the shipbreaking area of sitakundupazilla (bhatiary-kumira), chittagong, bangladesh. journal of geochemical exploration 125, 130–137. herath, d., pitawala, a., gunatilake, j. (2016). heavy metals in road deposited sediments and road dusts of colombo capital, sri lanka. journal of the national science foundation of sri lanka 44(2). jayawardana, d.t., ishiga, h., pitawala, h.m.t.g.a., (2012). geochemistry of surface sediments in tsunami-affected sri lankan lagoons regarding environmental implications. international journal of environmental science and technology 9, 41–55. jonathan, m.p., ram mohan, v., (2003). heavy metals in sediments of the inner shelf off the gulf o f mannar, southeast coast of india. marine pollution bulletin 46, 263–268. katupotha, j., (1989). coastal landforms during the holocene epoch in sri lanka: are they comparable to those in brazil and venezuela? international symposium on global changes in south america during the quaternary, sao paulo, brazil, 188-192. katupotha, k.n.j., (2007). (coastal landforms) the national atlas of sri lanka, second edition, survey department of sri lanka. 40-42. macdonald, d.d., carr, r.s., calder, f.d., long, e.r., ingersoll, c.g., (1996). development and evaluation of sediment quality guidelines for florida coastal waters. ecotoxicology 5(4), 253–278. mcbride, m. b., (1995). toxic metal accumulation from agricultural use of sludge: are usepa regulations protective?. journal of environmental quality 24(1), 5-18. muller, g. (1969). index of geoaccumulation in sediments of the rhine river. geojournal 2, 108-118. nayanananda, o. k. (2007). the study of economic significance of coastal region of sri lanka in the context of environmental changes of pre and post tsunami. coast conservation department and the ministry of environment and natural resources. newton, a., icely, j., cristina, s., brito, a., cardoso, a. c., colijn, f., ivanova, k., (2014). an overview of ecological status, vulnerability and future perspectives of european large shallow, semi-enclosed coastal systems, lagoons and transitional waters. estuarine, coastal and shelf science 140, 95-122. ramesh, r., subramanian, v., (1988). temporal, spatial and size variation in the sediment transport in the krishna river basin, india. journal of hydrology 98, 53-65. ranasinghe, p. n., ortiz, j. d., moore, a. l., mcadoo, b., wells, n., siriwardana, c. h. e. r., wijesundara, d. t. d. s., 2013. mid–late holocene coastal environmental changes in southeastern sri lanka: new evidence for sea level variations in southern bay of bengal. quaternary international298, 20-36. sarkar, s.k., francˇisˇkovic´-bilinski, s., bhattacharya, a., saha, m., bilinski, h., (2004). levels of elements in the surficial estuarine sediments of the hugli river, northeast india and their environmental implications. environment international 30, 1089–1098, selvaraj, k., ram mohan, v., szefer, p., (2004). evaluation of metal contamination in coastal sediments of the bay of bengal, india: geochemical and statistical approaches. marine pollution bulletin 49, 174–185. silva, p.n.m.p.d., (2015). distribution of heavy metals in sediments of hikkaduwa, galle, beruwalafisheriesharbors, sri lanka (unpublished thesis). post graduate institute of science, university of peradeniya. adikaram and pitawala/journal of tropical forestry and environment vol. 7, no. 02 (2017) 1-9 9 solali, a., ghandi, m.s., kasilingam, k., sriraman, e., (2013). heavy metal accumulation in the surface sediments off pondicherry, bay of bengal, south east coast of india. international journal of innovative science, engineering and technology 2(10), 5741-5753. subramanian v., jha, p.k., jergrieken, r., (1988). heavy metals in the ganges estuary. marine pollution bulletin 19, 290–293. taylor, s.r., mclennan, s.m., (1985). the continental crust: its composition and evolution. in: an examination of the geochemical record preserved in sedimentary rocks. blackwell scientific publications, oxford, edinburgh. 1-30. tomlinson, d. l., wilson, j. g., harris, c. r., jeffrey, d. w., (1980). problems in the assessment of heavy-metal levels in estuaries and the formation of a pollution index. helgoländermeeresuntersuchungen 33(1), 566. tornero, v., d'alcalà, m. r., (2014). contamination by hazardous substances in the gulf of naples and nearby coastal areas: a review of sources, environmental levels and potential impacts in the msfd perspective. science of the total environment 466, 820-840. wang, s. l., xu, x. r., sun, y. x., liu, j. l., li, h. b., (2013). heavy metal pollution in coastal areas of south china: a review. marine pollution bulletin 76(1), 7-15. wang, x.l., sato, t., xing, b.s., tao, s., (2005). health risks of heavy metals to the general public in tianjin, china via consumption of vegetables and fish. science of the total environment 350, 28–37. young, s. m., ishiga, h., roser, b. p., pitawala, a., (2014). geochemistry of sediments in three sectors of trincomalee bay, sri lanka: provenance, modifying factors and present environmental status. journal of soils and sediments 14(1), 204-217. zohra, b. s., habib, a., (2016). assessment of heavy metal contamination levels and toxicity in sediments and fishes from the mediterranean sea (southern coast of sfax, tunisia). environmental science and pollution research 23(14), 13954-13963. subasinghe and hettiarachchige /journal of tropical forestry and environment vol. 11 no. 02 (2021) 1-9 1 feature article endophytic fungal species in tropical trees: a review s.m.c.u.p. subasinghe and r.p. hettiarachchige centre for forestry and environment department of forestry and environmental science university of sri jayewardenepura, sri lanka abstract pathogenic fungi are common in forest ecosystems which cause diseases and sometimes death of plants, while some fungi live inside trees harmlessly without causing issues. sometimes, plants benefit from the presence of those endophytic fungi, such as gaining resistance to environmental stresses, protection from harmful pathogens etc. numerous studies have been conducted on such relationships between endophytic fungi and short-term agricultural crops. however, such studies are rare in the literature on tropical tree species which bear timber and non-timber values. this study illustrates the studies conducted on endophytic fungi in tropical trees and explores the potential use of such fungi for obtaining benefits. keywords: endophytic fungi, interactions, tropical trees, abundance 1. introduction fungi are essential components in every ecosystem, intimately associated with crucial processes like the decomposition, recycling, and transportation of nutrients in different environments. endophytic fungi are a group that colonize living, internal tissues of plants without causing immediate or overt adverse effects (bacon and white, 2000). however, they may be pathogenic during host senescence (rodriguez and redman, 2008). they are a taxonomically and ecologically heterogeneous group of organisms; mainly belonging to ascomycota, coelomycetes, and hyphomycetes (rajagopal et al., 2012). most endophytes are horizontally transmitted to their host plants through airborne spores. in contrast, some endophytes can vertically transmit to the next plant generations via seeds (hartley and gange, 2009). though endophytic fungi were known for over one hundred years, they did not receive much attention until the recent recognition of their pharmaceutical and ecological significance (gunatilaka, 2006). various relationships exist between fungal endophytes and their host plants, ranging from mutualistic or symbiotic to slightly pathogenic (schulz and boyle, 2005). symbiotic associations between fungi and photosynthetic organisms are both ancient and ubiquitous. the relationship of endophytes with hosts is described in different terms of host specificity, host recurrence, host selectivity etc. host specificity is the relationship where a fungus is restricted to a single plant species or a group of related species and not found in other unrelated plants in the same habitat (ananda and sridhar, 2002). host recurrence is the predominant occurrence of endophytic fungus on a particular host or a range of plant hosts. still, the fungus can also occur infrequently on other host plants in the same habitat. if a single fungal endophyte form relationship with two related plant hosts, but demonstrate more likely to one host, it is described as host selectivity (cohen, 2006). endophytic fungi commonly demonstrate host specificity at the plant species level, but environmental conditions can influence this specificity (cohen, 2004). at the same time, differences in endophytic fungal assemblage have been found in different tissues of the same plant species and even in other tissues of a single plant. this phenomenon reflects the tissues specificity (ganley and newcome, 2006). 2 2. positive and negative interactions between endophytic fungi and trees beneficial interactions between fungi and relevant hosts could be presented in different aspects. endophytic fungi produce many substances inside the host plants that have potential use in modern medicine, agriculture and industry such as antibiotics, anticancer compounds (michell et al., 2008). some endophytic fungi could produce different plant hormones to enhance the growth of their host plants (waqas et al., 2012). for example, the growth of wheat (triticumaestivum l.) could be enhanced by azospirillum sp. under drought stresses (dingle and mcgee, 2003). some produce different bioactive compounds, such as alkaloids, diterpenes, flavonoids, and isoflavonoids to increase their host plants' resistance to biotic and abiotic stresses (rodriguez et al., 2009). certain endophytic fungal species could also promote the accumulation of secondary metabolites (including important medicinal components or drugs) originally produced by plants. according to the references, these metabolites may be produced by both host plants and/or endophytic fungi (shwab and keller, 2008). endophytic fungi can protect their host plants from pathogens and pests (arnold et al., 2003). the foliar endophytes can reduce herbivory by producing alkaloids that are toxic to insects and vertebrates (schardl, 2001). the endophytic fungus acremonium coenophialum exhibited insecticidal activity against aphids (rhopalosiphum padi, schizaphis graminum) and milkweed bugs. cladosporium herbarum, a. alternata, rhodotorula rubra, epicoccum nigrum, cryptococcus sp., penicillium sp. and fusarium graminearum act as protectants to plants from herbivores (larran et al., 2002). senthilkumar et al., (2014) reported that phytochemicals such as dodecanoic acid, ethyl ester, phthalic acid, octyl 2-pentyl ester isolated from phomopsis sp. can be used as an insecticide. further, cladosporium oxysporum showed insecticidal activity against aphis fabae (bensaci et al., 2015). extracts of emericella nidulans, a. oryzae, a. tamarii and a. versicolor showed the insecticidal ability on spodoptera litura larvae with the maximum activity of a. versicolor (abraham et al., 2015). endophytes can actively or passively promote plant growth through different mechanisms. endophytic metabolites provide a variety of fitness to host plants enhanced by increasing plant resistance to biotic and abiotic stresses, as well as enhancing plant growth. many endophytes are capable of solubilization of phosphate, enhance uptake of phosphorus, nitrogen fixation and plant hormones such as auxin, abscisic, ethylene, gibberellins, and indole acetic acid (e.g., fusarium tricinctum alternate), which are important for plant growth regulation (khan et al., 2015; sandhiya et al., 2005). fungal endophytes the form mycorrhizal associations assists to distribute nutrients within the surrounding plants (franklin et al., 2014). the mechanisms of certain endophytic fungi induced resistance related to the nutritional status of the host, and thereby to increasing the fitness of plants by enhancing their tolerance to abiotic stress (lu et al., 2000). symbiotic fungi play an important role in the ecological community by decreasing the spoilage of land and water caused by excessive toxic organic insecticide, environmental degradation, industrial sewage, poisonous gases and loss of biodiversity (guo et al., 2008). due to the potential of microorganisms for bioaccumulation of heavy metals and other pollutants from the environment, it can enhance and increase plant growth (ma et al., 2011). due to that, endophytes may also play a direct or indirect role in the phytoremediation process and degradation of environmental toxins, indirectly through enhancing plant growth having the ability of phytoremediation and this accelerate phytoremediation process, or directly through degradation and/or accumulating pollutants (oses et al., 2008). for example, penicillium funiculosum acts against the copper stress and enhances the plant growth. therefore, it can be used in bioremediation of pollution in the cultivated area by stress mediating endophytes (khan and lee, 2013). subasinghe and hettiarachchige /journal of tropical forestry and environment vol. 11 no. 02 (2021) 1-9 3 3. potential for the use of positive impacts endophytes generated an interest among the scientists of microbial chemistry due to their potential to contribute to the discovery of new bioactive compounds. it has been suggested that the close biological association between endophytes and their plant hosts results in the production of a large number and diversity of biologically active molecules compared to epiphytes or soil-related microbes (strobel, 2003). moreover, the symbiotic nature of this relationship indicates that endophytic bioactive compounds are less toxic to the animal cells, as these chemicals do not kill the eukaryotic host system. this is particularly important to the researchers in the medical field as potential drugs may not adversely affect human cells (alvin et al., 2014). 4. the abundance of fungi in tropical trees endophytic fungi have been found in all plant species examined to date, including algae, mosses, conifers, angiosperms, palms and a variety of dicotyledonous shrubs and trees. studies conducted on the presence of endophytic fungi in commercially valuable tropical timber trees such as dipterocarpus tuberculatus, guarea guidonia, hevea brasiliensis, khaya anthotheca, and tectona grandis. in addition, similar studies were conducted on commercially valuable non-timber species in food and confectionary (mangifera indica, musa acuminate, theobroma cacao), medicine, (azadirachta indica, camptotheca acuminate, crocus sativus, ginkgo biloba, mesua ferrea, samanea saman, terminalia sp., vitex negundo) and enzyme production (calophyllum inophyllum). several authors have suggested that endophytes are especially diverse in tropical forests (table 01). table 01. fungal species identified in tropical tree species tree species no. of fungal species dominant species location and abundance reference b l s t f r aegle marmelos 10 alternaria sp. aspergillus sp. bipolaris crotonis cladosporium sp. colletotrichum sp. curvularia sp. daldinia sp. fusarium sp. nigrospora sp. phomopsis sp. schizophyllum sp. trichoderma sp. xylaria sp. l h l h h l h l l l l l l gond et al., 2007 artocarpus heterophyllus 1 colletotrichum sp. h sunkar et al., 2017 azadirachta indica 29 alternaria sp. aspergillus sp. colletotrichum sp. diaporthe sp. fusarium sp. penicillium sp. trichoderma sp. xylaria sp. l h l h h l l h l h l h l h h h l l l l h h l l l h chutulo et al., 2018 calophyllum inophyllum 8 cladosporium sp. discosia sp. h h hedge et al., 2011 4 fusarium sp. isaria sp. penicillium sp. pestalotiopsis sp. xylaria sp. h h h l l camptotheca acuminata >5 alternaria sp. fusarium sp. paecilomyces sp. phomopsis sp. rhizoctonia sp. h h h t l l h h lin et al., 2007 coffea arabica 1 glomerella cingulata h h sette et al., 2006 coffea robusta 2 glomerella cingulate phomopsis sp. h l sette et al., 2006 crocus sativus 12 alternaria sp. fusarium sp. penicillium sp. phytophthora sp. rhizoctonia sp. trichoderma sp. l h l h h l raj et al., 2013 dillenia indica 25 alternaria sp. aspergillus sp. bipolaris crotonis cladosporium sp. colletotrichum sp. daldinia sp. fusarium sp. nigrospora sp. phomopsis sp. schizophyllum sp. trichoderma sp. xylaria sp. l h h h h l l l h l l l prasher and kumar, 2021 diospyros celebica 7 aspergillus sp. fusarium sp. gliocladium sp. penicillium sp. phytophthora sp. trichoderma sp. l l l l l l h l l l l h l l l l l l mukrimin et al., 2021 diospyros crassiflora 7 clypeosphaeria sp. colletotrichum sp. penicillium sp. phomopsis sp. phyllosticta sp. xylaria sp. l l h h h l l douanla-meli and langer, 2012 dipterocarpus tuberculatus 9 daldinia sp. fusarium sp. penicillium sp. pestalotiopsis sp. phomopsis sp. phyllosticta sp. xylaria sp. l l l l l l l sutjaritvorakul et al., 2011 subasinghe and hettiarachchige /journal of tropical forestry and environment vol. 11 no. 02 (2021) 1-9 5 garcinia indica 6 aspergillus sp. fusarium sp. trichoderma sp. l h h l h h tejesvi et al., 2006 ginkgo biloba 1 muscodor albus h banerjee et al., 2010 guarea guidonia 14 colhotrichum sp. phomopsis sp. rhizoctonia sp. trichoderma sp. xylaria sp. h l h l l gamboa and bayman, 2001 hevea brasiliensis 58 colletotrichum sp. fusarium sp. penicillium sp. trichoderma sp. xylaria sp. h l l l l h l l h h gazis and chaverri, 2010 khaya anthotheca 10 colletotrichum sp. fusarium sp. phomopsis sp. xylaria sp. h l l h linnakoski et al., 2012 mangifera indica 7 aspergillus flavus aspergillus niger candida sp. cladosporium sp. penicillium sp. moniliella sp. trichoderma sp. h l h h l l h l h h l h l h l h h l l nayak, 2015 mesua ferrea 1 phomopsis sp. l l jayanthi et al., 2011 musa acuminata 6 colletotrichum sp. cordana musae dactylaria sp. deightoniella sp. guignardia sp. pyriculariopsis sp. h h h h h h photita et al., 2001 pinus attenuate 5 leploslrotnn sp. naemacyclus sp. h h carroll and carroll, 1978 pinus contoria 5 cladosporium sp. leploslrotnn sp. naemacyclus sp. h h h carroll and carroll, 1978 pinus monticola 2 leploslrotnn sp. h carroll and carroll, 1978 samanea saman 4 colletotrichum sp. nigrospora sp. penicillium sp. phomopsis sp. h l l l chareprasert et al, 2006 tectona grandis 7 alternaria sp. colletotrichum sp. fusarium sp. nigrospora sp. penicillium sp. phomopsis sp. schizophyllum sp. h h l l l l l chareprasert et al., 2006 6 terminalia arjuna 6 colletotrichum sp. phomopsis sp. trichoderma sp. tubercularia sp. h h h l h h h kouipou and boyom, 2019 terminalia catappa 7 colletotrichum sp. diaporthe sp. trichoderma sp. xylaria sp. l l h l kouipou and d boyom, 2019 terminalia chebula 4 colletotrichum sp. penicillium sp. xylaria sp. l h l l l kouipou and boyom, 2019 terminalia crenulate 4 colletotrichum sp. l kouipou and boyom, 2019 terminalia mantaly 6 colletotrichum sp. diaporthe sp. fusarium sp. l l l l kouipou and boyom, 2019 theoborma cacao 3 colletotrichum sp. fusarium sp. xylaria sp. h l l arnold et al., 2003 vitex negundo 9 alternaria sp. aspergillus flavus colletotrichum sp. discosia sp. fusarium solani lasiodiplodia sp. l l l l l h l l l l l sunayana et al., 2014 location of the tree: b=bark, f=fruit, l=leaf, r=root, s=stem, t=twig abundance of fungal species: h=high, l=low 4. conclusion the impacts of endophytic fungi can effectively be used for the efficient production of agriculturally, industrially and economically important plants and plant products. the rational application of endophytes to manipulate the microbiota, intimately associated with plants, can help in the enhancement of production of the agricultural product, increased production of key metabolites in medicinal and aromatic plants, as well as adaption to new bio-geographic regions through tolerance to various biotic and abiotic conditions (wani et al., 2015). references abraham, s., basukriadi, a., pawiroharsono, s. and sjamsuridzal, w., 2015. insecticidal activity of ethyl acetate extracts from culture filtrates of mangrove fungal endophytes. mycobiol, 43:137149. alvin, a., miller, k.i. and neilan, b.a., 2014. exploring the potential of endophytes from medicinal plants as sources of antimycobacterial compounds. microbiol, 169:483-495. ananda, k. and sridhar, k.r., 2002. diversity of endophytic fungi in the roots of mangrove species on the west coast of india. canadian journal of microbiology, 48:871-878. arnold, a.e., mejía, l.c., kyllo, d., rojas, e.i., maynard, z., robbins, n. and herre, e.a., 2003. fungal endophytes limit pathogen damage in a tropical tree. proceedings of the national academy of sciences, 100:15649-15654. arnold, a.e., maynard, z. and gilbert, g.s., 2001. fungal endophytes in dicotyledonous neotropical trees: patterns of abundance and diversity. mycological research, 105:1502-1507. subasinghe and hettiarachchige /journal of tropical forestry and environment vol. 11 no. 02 (2021) 1-9 7 arnold, a.e. and lutzoni, f., 2007. diversity and host range of foliar fungal endophytes: are tropical leaves biodiversity hotspots. ecology, 88:541-549. bacon, c.w. and white, j.f., 2000. microbial endophytes. dekker, new york, pp 341–388 banerjee, d., 2011. endophytic fungal diversity in tropical and subtropical plants. res j microbiol, 54-62. banerjee, d., strobel, g., geary, b., sears, j., ezra, d., liarzi, o. and coombs, j., 2010. muscodor albus strain gba, an endophytic fungus of ginkgo biloba from united states of america, produces volatile antimicrobials. mycology, 1:179-186. bensaci, o.a., daoud, h., lombarkia, n. and rouabah, k., 2015. formulation of the endophytic fungus cladosporium oxysporum berk and ma curtis, isolated from euphorbia bupleuroides subsp. luteola, as a new biocontrol tool against the black bean aphid (aphis fabae scop.). journal of plant protection research, 55. carroll, g.c. and carroll, f.e., 1978. studies on the incidence of coniferous needle endophytes in the pacific northwest. canadian journal of botany, 56:3034-3043. chareprasert, s., piapukiew, j., thienhirun, s., whalley, a.j. and sihanonth, p., 2006. endophytic fungi of teak leaves tectona grandis l. and rain tree leaves samanea saman merr. world journal of microbiology and biotechnology, 22:481-486. chutulo, e.c. and chalannavar, r.k., 2018. endophytic mycoflora and their bioactive compounds from azadiracta indica: a comprehensive review. journal of fungi, 4:42. cohen, s.d., 2004. endophytic-host selectivity of discula umbrinella on quercus alba and quercus rubra characterized by infection, pathogenicity and mycelial compatibility. european journal of plant pathology, 110:713-721. cohen, s.d., 2006. host selectivity and genetic variation of discula umbrinella isolates from two oak species: analyses of intergenic spacer region sequences of ribosomal dna. microbial ecology, 52:463-469. dingle, j. and mcgee, p.a., 2003. some endophytic fungi reduce the density of pustules of puccinia recondita f. sp. tritici in wheat. mycological research, 107:310-316. douanla-meli, c. and langer, e., 2012. diversity and molecular phylogeny of fungal endophytes associated with diospyros crassiflora. mycology, 3:175-187. dreyfuss, m.m. and chapela, i.h., 1994. potential of fungi in the discovery of novel, low-molecular weight pharmaceuticals. discovery of novel natural products with therapeutic potential, 49-80. faeth, s.h. and hammon, k.e., 1997. fungal endophytes in oak trees: long‐term patterns of abundance and associations with leafminers. ecology, 78:810-819. franco f.v., moreno r.s. and ghneim h.t., 2021. are endophytic bacteria an option for increasing heavy metal tolerance of plants? a meta-analysis of the effect size. frontiers in environmental science, 294. gamboa, m.a. and bayman, p., 2001. communities of endophytic fungi in leaves of a tropical timber tree (guarea guidonia: meliaceae). biotropica, 33:352-360. ganley, r.j. and newcombe, g., 2006. fungal endophytes in seeds and needles of pinus monticola. mycological research, 110:318-327. gazis, r. and chaverri, p., 2010. diversity of fungal endophytes in leaves and stems of wild rubber trees (hevea brasiliensis) in peru. fungal ecology, 3:240-254. gond, s.k., verma, v.c., kumar, a., kumar, v. and kharwar, r.n., 2007. study of endophytic fungal community from different parts of aegle marmelos correae (rutaceae) from varanasi (india). world journal of microbiology and biotechnology, 23:1371-1375. gunatilaka, a.a.l., 2006. natural products from plant-associated microorganisms: distribution, structural diversity, bioactivity, and implication of their occurrence. j nat prod, 69:509-526 guo, b., wang, y. and sun, x., 2008. tang k. bioactive natural products from endophytes: a review. appl biochem microbiol, 44:136-142 hartley, s.e. and gange, a.c., 2009. impacts of plant symbiotic fungi on insect herbivores: mutualism in a multitrophic context. annu rev entomol 54:323-342 8 hegde, s.v., ramesha, a. and srinvas, c., 2011. optimization of amylase production from an endophytic fungi discosia sp. isolated from calophyllum inophyllum. int j agric technol, 7:805-813. huang, w.y., cai, y.z., hyde, k.d., croke, h. and sun, m., 2008. biodiversity of endophytic fungi associated with 29 traditional chinese medicinal plants. fungal diversity, 33:61-75. jayanthi, g., kamalraj, s., karthikeyan, k. and muthumary, j., 2011. antimicrobial and antioxidant activity of the endophytic fungus phomopsis sp. gjjm07 isolated from mesua ferrea. int j curr sci, 1:85-90. khan, a.l. and lee, i.j., 2013. endophytic penicillium funiculosum lhl06 secretes gibberellin that reprograms glycine max l. growth during copper stress. bmc plant biol., 13:86. khan, a.r., ullah, i., waqas, m., shahzad, r., hong, s.j., park, g.s., jung, b.k., lee, i.j. and shin, j.h., 2015. plant growth-promoting potential of endophytic fungi isolated from solanum nigrum leaves. world j microbiol biotechnol, 31:1461-1466. kouipou, t.r.m. and boyom, f.f., 2019. endophytic fungi from terminalia species: a comprehensive review. journal of fungi, 5:43. larran, s., perelló, a., simo, m.r. and moreno, v., 2002. isolation and analysis of endophytic microorganisms in wheat (triticum aestivum l.) leaves. world j microbiol biotechnol, 18:683686. lin, x., lu, c., huang, y., zheng, z., su, w. and shen y., 2007. endophytic fungi from a pharmaceutical plant, camptotheca acuminata: isolation, identification and bioactivity. world journal of microbiology and biotechnology, 23:1037-1040 linnakoski, r., puhakka-tarvainen, h. and pappinen, a., 2012. endophytic fungi isolated from khaya anthotheca in ghana. fungal ecology, 5:298-308. lu, h., xou, w.x., meng, j.c., hu, j. and tan, r.x., 2000. new bioactive metabolites produced by colletotrichum sp., an endophytic fungus in artemisia annua. plant sci., 151:67-73. ma, y., prasad, m.n.v., rajkumar, m. and freitas, h.j.b.a., 2011. plant growth promoting rhizobacteria and endophytes accelerate phytoremediation of metalliferous soils. biotechnology advances, 29:248-258. michell, j., 2008. is psychometrics pathological science? measurement, 6:7-24. mukrimin, m., musdalifah, n., larekeng, s.h., sultan, s. and christita, m., 2021, november. fungal diversity inhabiting tissues of ebony (diospyros celebica bakh.) in urban forest. in iop conference series: earth and environmental science, 886:012-031 nayak, b.k., 2015. isolation and identification of phylloplane and endophytic fungi from one ornamental plant, mangifera indica. international journal of technochem research, 1:188192. oses, r., valenzuela, s., freer, j., sanfuentes, e. and rodriguez, j., 2008. fungal endophytes in xylem of healthy chilean trees and their possible role in early wood decay. fungal diversity, 33: 77– 86. photita, w., lumyong, s., lumyong, p. and hyde, k.d., 2001. endophytic fungi of wild banana (musa acuminata) at doi suthep pui national park, thailand. mycological research, 105:1508-1513. prasher, i.b. and kumar, v., 2021. diversity of endophytic fungi associated with dillenia indica l., an ethnomedicinal plant. current research in environmental & applied mycology, journal of fungal biology, 11:532-559. raj, p., khan, s.s., modak, m., lone, z.a., rather, s.a. and yaqoob, m., 2013. biodiversity of endophytic fungi in saffron (crocus sativus) and antimicrobial activity of their crude extract. indo am j pharm res, 3:3702-3713. rajagopal, k., maheswari, s. and kathiravan, g., 2012. diversity of endophytic fungi in some tropical medicinal plants-a report. afr. j. microbiol. res., 6:2822-2827. rodriguez, r. and redman, r., 2008. more than 400 million years of evolution and some plants still can’t make it on their own: plant stress tolerance via fungal symbiosis. j exp bot 59:1109-1114 subasinghe and hettiarachchige /journal of tropical forestry and environment vol. 11 no. 02 (2021) 1-9 9 rodriguez, r.j., white jr, j.f., arnold, a.e. and redman, a.r.a., 2009. fungal endophytes: diversity and functional roles. new phytologist, 182:314-330. saikkonen, k., faeth, s. h., helander, m. & sullivan, t. j., 1998, annu. rev. ecol. syst. 29:319-343 sandhiya, g.s., sugitha, t.c., balachandar, d. and kumar, k., 2005. endophytic colonization and in planta nitrogen fixation by a diazotrophic serratia sp. in rice. indian j exp biol, 43:802-807. schardl, c.l., 2001. epichloe festucae and related mutualistic symbionts of grasses. fungal genet biol, 33:69-82. senthilkumar, n., murugesan, s., babu, d.s. and rajeshkannan, c., 2014. gc-ms analysis of the extract of endophytic fungus, phomopsis sp. isolated from tropical tree species of india, tectona grandis l. int j innov res sci eng tech, 3:10176-10179 sette, l.d., passarini, m.r.z., delarmelina, c., salati, f. and duarte, m.c.t., 2006. molecular characterization and antimicrobial activity of endophytic fungi from coffee plants. world journal of microbiology and biotechnology, 22:1185-1195. shwab, e.k. and keller, n.p., 2008. regulation of secondary metabolite production in filamentous ascomycetes. mycological research, 112:225-230. strobel, g.a., 2003. endophytes as sources of bioactive products. microbes infect, 5:535-544 sunayana, n., nalini, m.s., sampath kumara, k.k. and prakash, h.s., 2014. diversity studies on the endophytic fungi of vitex negundo l. mycosphere, 5:578-590. sunkar, s., sibitha, v., nachiyar, v., pandurangan, p. and renugadevi, k., 2017. bioprospecting endophytic fungus colletotrichum sp. isolated from artocarpus heterophyllus for anticancer activity. research journal of biotechnology, 12:46-56. sutjaritvorakul, t., whalley, a.j.s., sihanonth, p. and roengsumran, s., 2011. antimicrobial activity from endophytic fungi isolated from plant leaves in dipterocarpous forest at viengsa district nan province, thailand. journal of agricultural technology, 7:115-121. tejesvi, m.v., mahesh, b., nalini, m.s., prakash, h.s., kini, k.r., subbiah, v. and shetty, h.s., 2006. fungal endophyte assemblages from ethnopharmaceutically important medicinal trees. canadian journal of microbiology, 52:427-435. wani, z.a., ashraf, n., mohiuddin, t. and riyaz-ul-hassan, s., 2015. plant-endophyte symbiosis, an ecological perspective. appl. microbiol. biotechnol, 99:2955-2965. waqas, m., khan, a.l., kamran, m., hamayun, m., kang, s.m., kim, y.h. and lee, i.j., 2012. endophytic fungi produce gibberellins and indoleacetic acid and promotes host-plant growth during stress. molecules, 17:10754-10773. dasanayaka and wijeyaratne. /journal of tropical forestry and environment vol. 07, no. 01 (2017) 65-73 cultivation of schizophyllum commune mushroom on different wood substrates p.n. dasanayaka * and s.c. wijeyaratne department of botany, university of sri jayewardenepura, sri lanka date received: 01-05-2017 date accepted: 05-06-2017 abstract schizophyllum commune is an edible mushroom grown on wood under natural conditions. present study focused on cultivation of s.commune on different wood substrates since it is not commercially cultivated. a pure culture of s. commune was obtained by growing a tissue of the mushroom on potato dextrose agar (pda) medium. spawns were produced by growing the mycelium on paddy grains. mushroom was cultivated on sawdust of seven different wood substrates. the maximum yield was observed in sawdust of jackfruit (artocarpus heterophyllus) followed by sawdust of rambutan (nephelium lappaceum) and country almond (terminalia catappa). a significant difference was not observed when mango (mangifera indica) elephant apple (dillenia indica), tulip wood tree (harpullia arborea) and thungfaa (alstonia macrophylla) sawdust used as substrate. the lowest yield was observed in thungfaa (alstonia macrophylla) sawdust. effect of some additives on the yield was studied and significant difference in yield was observed when rice bran and used-tea leaves used as additives. effect of rice bran on yield was studied using different ratios of sawdust to rice bran and the highest was observed in 2:1 ratio of sawdust to rice bran. the best incubating temperature for mycelial growth on the substrate was 35 0 c. the composition of the mushroom on a dry weight basis was; 71.4% moisture, 23.35% crude protein and 6% ash. tested wood species are promising substrates for cultivation of s.commune as cottage industry. key words: schizophyllum commune, mushroom, cultivation, sawdust, spawn 1. introduction mushrooms are fleshy, spore-bearing fruiting bodies of basidiomycete fungi, typically produced above ground on soil or on its food source. edible mushrooms are recommended by the fao as food, to meet protein requirement of developing countries, the large proportion of which depends mainly on cereals. in general edible mushrooms are low in fat and calories, rich in vitamins b, d, k and sometimes vitamins a and c (alam et al., 2007), contain more protein than any other food of plant origin and are also a good source of mineral nutrients (qin, 1989).therefore great attention has been paid on mushroom as ‘functional food’ to complement and supplement a healthy diet as well as for their significant role in human disease control (chang 1999, khan et al., 2009). s.commune is also an edible fungus and growing under natural conditions especially during rainy season on decaying woods. it has been isolated all continents except antarctica (khatua et al., 2013). s.commune is known to be a very good source of proteins, vitamins, lipids and mineral elements (adejoye et al., 2007). it is rich in p, mg, k, and se and high dietary fiber content more than 50% of the net weight (ghorai et al., 2009). although s.commune grows on decaying woods of different species under natural conditions there are no records on its commercial cultivation. therefore present study was undertaken to evaluate the possibility of cultivating s.commune on freely available wood substrates and their effect on yield of the mushroom, and the effect of temperature on the growth of s.commune mycelium on the substrate in compost bags. *correspondence: nilanthiedas@sjp.ac.lk tel: +94718122358 issn 2235-9370 print / issn 2235-9362 online ©2017 university of sri jayewardenepura 65 2. materials and methods this study was conducted at the department of botany, university of sri jayewardenepura, nugegoda, sri lanka. fruiting bodies of schizophyllum commune growing on decaying mango wood were collected from eheliyagoda area of rathnapura district, sri lanka. production of spawn pure culture of the s.commune mycelium was obtained by growing a tissue of fruiting body aseptically on pda medium. boiled paddy grains were used as the substrate to produce the spawn. boiled paddy grains were sterilized at 121 0 c under 15 lb/inch 2 in conical flasks. after the sterilization the substrate was inoculated with 1 cm 2 mycelial blocks of s.commune grown on pda at room temperature and inoculated the substrate was incubated at room temperature. effect of kinds of sawdust on the yield of the mushroom collection of sawdust sawdust of seven different woods; alstonia macrophylla, artocarpus heterophyllus, harpullia arborea, mangifera indica, dillenia indica, nephelium lappaceum and terminalia catappa were collected from two different saw mills of eheliyagoda (table 01) and was sun dried for about 4-5 days depending on its moisture content. table 01: different kinds of sawdust used in the study. english name local name scientific name family thungfaa hawari nuga alstonia macrophylla apocynaceae jackfruit kos artocarpus heterophyllus moraceae tulip wood tree na imbul harpullia arborea sapindaceae mango amba mangifera indica dilleniaceae elephant apple honda para dillenia indica sapindaceae rambutan rambutan nephelium lappaceum combretaceae country almond kottamba terminalia catappa anacardiaceae preparation of different wood substrates composition of the substrate sawdust 400 g rice bran 40 g caco3 10 g mgso4 1 g water 600 ml polypropylene bags (10.5 cm x 15 cm) were filled with 400 g of thoroughly mixed substrates and mouths were plugged by inserting water absorbing cotton wool with the help of plastic rings. each of seven treatments was replicated five times. t1: sawdust of alstonia macrophylla (thungfaa) t2: sawdust of artocarpus heterophyllus (jackfruit) t3: sawdust of harpullia arborea (tulip wood tree) t4: sawdust of mangifera indica (mango) t5: sawdust of dillenia indica (elephant apple) t6: sawdust of nephelium lappaceum (rambutan) t7: sawdust of terminalia catappa (country almond) the bags were autoclaved at 121 0 c under 15 lb/inch 2 pressure and allowed to cool overnight. thereafter each bag was inoculated with two tea spoons of prepared spawn of s.commune mushroom. the inoculated bags of seven treatments with five replicates were arranged following randomized 66 dasanayaka and wijeyaratne. /journal of tropical forestry and environment vol. 07, no. 01 (2017) 65-73 block design (rbd) and incubated at room temperature under dark conditions till the mycelium grew throughout the substrates. then the bags were opened and watered three times a day. first flush of fruiting bodies was harvested 30 days after inoculation. the fresh weight of mushroom harvested from each bag was recorded. effect of some additives on yield of the mushroom effect of four different additives: coir dust, rice bran, dried ipilipil leaves and used tea leaves, on the yield of s. commune mushroom was determined by adding 10% of additive to the basal medium. effect of rice bran on yield effect of rice bran (the best out of tested additives) on the yield of s.commune mushroom was studied using six different ratios of sawdust to rice bran. substrates were prepared mixing sawdust and rice bran in different ratios. sawdust of artocarpus heterophyllus was used for this experiment. t1 sawdust to rice bran ratio 6:1 t2 sawdust to rice bran ratio 5:1 t3 sawdust to rice bran ratio 4:1 t4 sawdust to rice bran ratio 2:1 t5 sawdust to rice bran ratio 1:1 t6 sawdust to rice bran ratio 1:0 (control experiment) the cultivation bags of six treatments were prepared with five replicates. sterilized substrate filled bags were inoculated with spawns of s.commune mushroom. the inoculated bags of six treatments with five replicates were arranged following randomized block design (rbd) and incubated at room temperature till the mycelium grew throughout the substrate. they were opened and watered three times a day. first flush of fruiting bodies were harvested 30 days after the inoculation. the fresh weight of mushroom harvested from each bag was recorded. effect of temperature on mycelial growth in compost bag effect of temperature on the growth of mycelium on the substrate in compost bags were studied using six different temperatures: 15 0 c, 20 0 c, 25 0 c, 30 0 c, 35 0 c and 40 0 c. the substrate was prepared using artocarpus heterophyllus sawdust, rice bran, caco3 and mgso4 with five replicates for each temperature. the distance of the mycelial growth from the place of inoculation was measured daily until it covered the substrate in the bag completely. determination of moisture, ash and total nitrogen content of s.commune mushroom two grams of the mushroom was dried in an oven at 105 0 c until the sample gave a constant weight to determine the moisture content. two grams of dried mushroom weighed accurately into a porcelain crucible was ignited in a muffle furnace at 550 0 c until gray ash resulted. it was left to cool and weight of the sample was recorded. total nitrogen content of the mushroom was determined by the standard micro-kjeldal procedure. following this method protein content of the sample was calculated by multiplying total nitrogen content by 6.25. 67 2. results growth of white mycelium around the tissue was observed three days after inoculation on pda medium. growing of septate mycelium with clamp connections was observed under the microscope confirming its growth. the yield of s. commune mushroom grown on sawdust of seven different wood species is shown in figure 1. significant variation was found in the yield of the mushroom grown on these seven different substrates. the maximum yield was observed with sawdust of artocarpus heterophyllus (t2) followed by sawdust of terminalia catappa (t7) nephelium lappaceum (t6) and relatively lower yields were recorded when mangifera indica (t4) dillenia indica (t5), harpullia arborea (t3) and alstonia macrophylla (t1) sawdust used as substrates. the lowest yield was observed in alstonia macrophylla sawdust. figure 1: yield of s. commune growing on different wood substrates rice bran treatment and used-tea leaves treatment showed significant difference in yield when compared to the control. there was no significant difference in yield when ipilipil leaves and coir dust were used as substrate (figure 2). 68 dasanayaka and wijeyaratne. /journal of tropical forestry and environment vol. 07, no. 01 (2017) 65-73 y ie ld ( g /b a g ) 1.6 1.4 1.2 1 0.8 0.6 0.4 0.2 0 1 5 11 16 20 harvesting time (days) control rice bran ipilipil leaves coir dust used tea leaves figure 2: yield of s. commune with four different additives the mushroom was cultivated using six different ratios of sawdust to rice bran to find out the most suitable ratio for its growth. the best yield was obtained when the sawdust to rice bran ratio was 2:1. the yield decreased when the ratio was increased or decreased from 2:1 ratio (figure 3). figure 3: mean yield of s.commune mushroom on substrates with different ratios of sawdust to rice bran. mean number of mushroom harvested from bag was also recorded and relatively higher number of mushrooms were harvested from bags which filled with sawdust to rice bran with 4:1, 2:1, and 1:1 ratios (figure 4). 69 figure 4: mean number of s.commune mushrooms per bag on substrates with different ratios of sawdust to rice bran. results revealed that the best temperature for mycelial growth was 35 0 c and spawn running took 11 days after inoculation to cover the whole culture bag at 35 0 c while spawn running time was longer at all other tested temperatures (at 30 0 c, 25 0 c and 20 0 c it took 13, 21 and 24 days respectively) (figure 5). no growth of mycelium was observed at 15 0 c and 45 0 c. the composition of the mushroom on a dry weight basis was; 71.4% moisture, 23.35% crude protein and 6% ash. m y ce li u m f ro m t h e p la ce o f in o cu la ti o n ( cm ) s p re a d o f 8.0 30 0 c 35 0 c 25 0 c 20 0 c 7.0 6.0 5.0 4.0 3.0 2.0 1.0 0.0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 days after inoculation figure 5: effect of temperature on mycelial growth of s.commune 4. discussion mushrooms depend on the substrate for nutrition and the substrate is normally a source of lignocellulose material which support growth, development and fruiting of mushrooms (chang and miles, 2004). decaying wood is a well-known substrate for the growth of s. commune mushroom. therefore the mushroom was cultivated on seven different wood substrates for the recommendation of 70 dasanayaka and wijeyaratne. /journal of tropical forestry and environment vol. 07, no. 01 (2017) 65-73 more suitable substrate for the commercial cultivation of this mushroom. significant variation was found in the yield of s. commune mushroom grown on sawdust of seven different wood species. the maximum yield was observed with sawdust of artocarpus heterophyllus followed by sawdust of nephelium lappaceum and terminalia catappa. a significant difference was not observed when mangifera indica, dillenia indica, harpullia arborea and alstonia macrophylla sawdust used as substrates. the lowest yield was observed in alstonia macrophylla sawdust. the results of the present study are supported by findings of the study conducted by ashrafuzzaman et al., 2009. they have studied effect of sawdust of acacia nilotica (babul tree), michelia champaca (teak shambul), dipterocarpus alartus (garjan), leucaena glauca (ipilipil), artocarpus heterophyllus (jackfruit), mangifera indica (mango), albizia saman (raintree), tectona grandis (teak), bombax ceiba (silk cotton), dalbergia sissoo (blackwood – tree) on the growth and yield of shitake mushroom (lentinus edodes). significantly faster mycelial growth has been observed on jackfruit substrate compared to other substrates. higher number of primodia and effective fruiting bodies have been recorded on jackfruit sawdust. it has been found that mycelial running rate was secondly higher on mango sawdust and have not shown any significant difference when babul tree, teak and silk cotton sawdust used as substrate. ediriveera et al.,(2015) have also investigated the effect of banana leaves, coconut leaves, paddy straw and coir dust on the growth and yield of s. commune. higher rate of mycelial growth has been observed in mixture containing banana leaves and not even a sign of mycelial growth has been observed in the medium containing paddy straws. significantly higher yields have been recorded for coconut leaves and coir dust containing mixtures. regardless of the main ingredient used, starch – based supplements such as rice bran, wheat bran, millet, rye or corn can be added at 10 to 40% of dry weight to the main ingredient (royse et al., 1990; royse 1996; ivan et al., 2003). nawanze et al., 2005 reported some of the proven additives induce fruiting body formation. rice bran, cassava peels, carbohydrates such as glycogen, natural extracts like yeast and vegetable oils and fish oil found as effective additives. the yield of s.commune was evaluated with four different additives to find out the best additive towards the increased production. rice bran treatment and used-tea leaves treatment showed significant difference in yield when compared to the control. there was no significant difference in yield when ipilipil leaves and coir dust were used as additives. the best yield was obtained when the sawdust to rice bran ratio was 2:1. when water is added to the medium (1:1), rice bran get adhered and cause the reduction in bulkiness and this is not the case when there is more sawdust in the substrate. the control contained only sawdust, caco3 and mgso4 and the mycelium did not grow well on it. after opening the control bag a very small number of buttons appeared and these even did not open up indicating the poor nutritional status of the substrate. since rice bran is proven to be as an effective additive and it is readily available in sri lanka which can be used as potential additive. an experiment was carried out to see the effect of rice bran on yield of mushroom using six different ratios of sawdust to rice bran. mean number of mushroom harvested from bag was also recorded and relatively higher numbers of mushrooms were harvested from bags which filled with sawdust to rice bran with 4:1, 2:1, and 1:1 ratios. temperature is a very important environmental factor for mycelium growth of fungi. results revealed that the best temperature for s. commune mycelial growth was 35 0 c. the mycelial growth appeared to be suppressed at the temperatures higher or lower than 35 0 c. jonathan (2002) also reported that the growth of s. commune as inhibited at 45 0 c and 50 0 c. the composition of the mushroom on a dry weight basis was; 71.4% moisture, 23.35% crude protein and 6% ash. incorporation of rice bran into the wood substrates enhanced mushroom 71 production. tested wood species are promising substrates for cultivation of s.commune as cottage industry. 5. conclusions artocarpus heterophyllus sawdust appeared as the most suitable substrate out of the tested substrates for cultivation of s.commune in compost bags. rice bran promoted the mushroom production and sawdust to rice bran ratio 2:1 gave the highest yield. optimum temperature for the mycelial growth and mushroom production was 35 0 c. s.commune mushroom can be harvested 30 days after inoculation of the spawn into compost bags. wood substrates of terminalia catappa and nephelium lappaceum were also promising substrates for commercial production of s.commune mushroom. relatively higher protein content of the mushroom and availability of wood substrates in sri lanka make commercial cultivation of s.commune as economically feasible cottage industry. references adejoye, o.d., adebayo-tayo, b.c., ogumjobi, a.a., afolabi, o.o. 2007. phytochemical studies on schizophyllum commune (fries) a nigerian fungus. world applsci j. 2(1),73-76. alam, n., khan, a., hossian m.s., amin, s.m.r., khan, l.a.2007 nutritional analysis of dietary mushroom pleurotus florida egger and pleurotus sajorcaju (fr) singer. bangladesh j mushroom 1(2):1-7). ashrafuzzaman, m., kumruzzaman, a.k.m., ismail, m.r., shahidullah fakir, s.a. 2009. substrate affects growth and yield of shitake mushroom. african journal of biotechnology. 8(13),29993006. chang, s. 1999. world production of cultivated edible and medicinal mushroom in 1997 with emphasis on lentinus edodes (berk) singer in china int i med mushrooms. 1,291-300. chang, s.t. and miles, p.g. 2004. mushroom cultivation, nutritional value, medicinal effect, and environmental impact, 2 nd ed. crc press, boca raton, fl. chang, s.t. and quimio, t.h. 1976. tropical mushroom biological nature and cultivation methods. ediriveera, s.s., wihjesundara, r.l.c., nanayakkara c.m., weerasena o.v.d.s.j 2015. comparative study of growth and yield of edible mushrooms, schizophyllum commune fr., auricularia polytricha (mont.) sacc.and lentinus squarrosulus mont. on lignocellulosic substrates. micosphere 6(6):760-765. ghorai, s., banik, s.p., verna, d., chowdhury, s., mukherjee, s., khowala, s. 2009. fungal biotechnology in food and feed processing. food res int. 42,577-587. ivan, h.r., antonio, c.m., jose, o.m., jose, c.b. 2003. supplementation of sugarcane bagasse with rice bran and sugarcane molasses for shitake (lentinula edudes) spawn production. brazil j. microbiol. 34, 61-65. jonathan s.g., 2002. vegetative growth requirements and antimicrobial activities of some higher fungi in nigeria. phd thesis, university of ibadan, ibadan, nigeria. khan, m.a., khan, l.a., hossain, m.s., tania, m., uddin, m.n. 2009. investigation on nutritional composition of common edible and medicinal mushrooms cultivated in bangladesh. bangladesh j mushroom. 3(1),21-28. khatua, s., paul, s., acharya, k. 2013. mushroom as the potential source of new generation of antioxidant: a review. research j. phar and tech 6(5), 496-505. nawanze, p.l., khan, a.u., amesh, j.b., umoh, v.j. 2005. the effect of the interaction of various spawn grains with different culture medium on carophore dry weights and stipe and pileus diameter of lentinus squarrosuhus (mont) singer afr j biotechnol. 4(7),615-619. 72 dasanayaka and wijeyaratne. /journal of tropical forestry and environment vol. 07, no. 01 (2017) 65-73 qin, s.x., 1989. effect of different cultivation materials on nutritive composition of pleurotus fruiting bodies. edible fungi of china, 3:12-13. royse, d.j. 1996. yield simulation of shitake by millet supplementation of wood chip substrate. mushroom biol. mushroom prod. 2, 277-283. royse, d.j., bahler, b.d., bahler, c.c. 1990. enhanced yield of shitake by saccharide amendment of the synthetic substrate. appl environ, microbiol, 56, 479-482. 73 chukwu and osho. /journal of tropical forestry and environment vol. 7, no. 02 (2017) 39-48 39 nonlinear height-stump diameter models for tectona grandis linn. f. stands in omo forest reserve, nigeria o. chukwu* and j.s.a. osho department of forest resources management, university of ibadan, ibadan, nigeria date received: 26-09-2017 date accepted: 03-12-2017 abstract illegal exploitation of timber species in developing countries have increased over the years. though, there is dearth of empirical models for describing the dimension, structure, quality and estimating quantity of a removed tree needed for assessment of damage due to catastrophic events, creating historical records of previous management activities and for conviction of illegal loggers. the objective of this study was to develop and test non-linear models that can effectively estimate individual tree merchantable height (ht) from stump diameter (ds) for tectona grandis stands in omo forest reserve, nigeria, for timber valuation in case of illegal felling. thirty-six temporary sample plots (tsps) of size 25x25 m were laid randomly in six age strata of t. grandis; 26, 23, 22, 16, 14, and 12 years specifically. diameter at breast height, ht and ds were measured for all living t. grandis trees within the 36 tsps. least square method was used to convert the counted stumps into harvested stem height. four ht-ds models were fitted and evaluated. the ht-ds relationship was best described by square model which gave least values of root mean square error (0.083) and akaike information criterion (-7578). this study revealed that height estimation was realistic even when the only information available was stump diameter. the square model was validated using independent data not used in the model calibration and was found to be appropriate for estimating the height of t. grandis stands in omo forest reserve, nigeria. keywords: tree height, non-linear model, stump diameter, square, tectona grandis 1. introduction one of the major problem facing tropical forests in developing countries is illegal logging. nevertheless, nigerian forests lands have been decreasing steadily due to the indiscriminate felling of trees and activities of illegal loggers (emeghara, 2012; ikuomola et al. 2016). lack of empirical information on the dimensions of trees removed from a forest could act as impediment in the conviction of illegal loggers. however, in judicial proceedings, relevant facts are required to be backed up with quantifiable evidence (evidence act, 1990). according to adebagbo (1992), a total of 298 trees comprising 19 different valuable species in the year 1990 were illegally extracted from supoba forestry reserve in edo state of nigeria but log dimensions were unknown. the relationship between tree height and stem diameter is one of the most important components of forest structure and growth and yield models (soares and tome, 2002). estimations of timber volume, site index, succession, carbon sequestration (spurr, 1952; botkin et al., 1972; kurz et al., 1992; vanclay, 1994; peng et al., 2001), as well as stand description and damage appraisals (parresol, 1992; zhang, 1997) are highly related to the tree height-diameter relationship. *correspondence: onye20042000@yahoo.com tel: +23 48032633835 issn 2235-9370 print/issn 2235-9362 online © university of sri jayewardenepura 40 however, tree height measurement is difficult and tedious task in forest inventory. the occurrence of visual obstacles, much time requirement and the chance of observer error and are among the main difficulties in measuring tree height (colbert et al., 2002; krisnawati et al., 2010) especially in dense forest. by contrast, tree variables such as diameter at breast height (dbh) and stump diameter (ds) are easy to measure with simple instruments, little investment of time and cost and with a high level of accuracy. hence, stem diameters are good predictors of height (lumbres et al., 2011; ahmadi, 2013). consequently, numerous reasons could necessitate the reconstruction of height and/or size of removed trees. these reasons include; describing the structure of a removed tree, creating historical records of past management activities, reviewing harvesting practices, assessing damage due to catastrophic events and establishing loss due to indiscriminate and/or illegal felling. previous studies have shown that tree stump diameter (ds) is highly correlated with diameter at breast height (dbh), and as such have being used in place of dbh to predict most tree growth variable especially in the case of illegal logging (osho, 1983; westfall, 2010; özçelík et al., 2010; shamaki and akindele, 2013; chukwu, et al., 2017). previous studies (osho, 1983; westfall, 2010; özçelík et al., 2010; shamaki and akindele, 2013) have been able to estimate volume of removed trees from stump diameter. however, volume of a tree alone might not be enough in describing a removed tree, especially in judicial proceedings. hence, information about other growth characteristic of a removed tree such as height is required to ascert ain claims and aid successful establishment and description of value of the tree loss. furthermore, in some situation, tree heights can be more valuable than its volume, for instance, in a plantation established for pole rather than timber. the ability to develop models that can easily and accurately estimate tree height from stem diameter for tectona grandis will guide the forester manager on the estimation of the forest stock (shamaki and akindele, 2013), as well as quantification and valuation of a removed tree (osho, 1983), especially in the case of illegal logging. however, this study aimed at developing models for estimating merchantable height from stump diameter of t. grandis plantations in omo forest reserve, nigeria, which will serve as tool in estimation of timber lost, descriptive evidence for a removed tree vertical length in litigation process as well as creating historical records of past management activities of the forest reserve. 2. materials and methods 2.1 study area this study was carried out at area j4 of omo forest reserve in ijebu-ode east local government area of ogun state, nigeria. the reserve is situated between latitude 6o 35׳ to 7o 05׳ n and longitudes 4o e with a total land area of 139,100 ha. the reserve is bounded by benin-shagamu expressway ׳to 4o 40 ׳9 to the south and omo river and oni river to the east. the reserve lies within the equatorial belt and has a mean annual rainfall of 1,200 mm and average elevation of about 91.47 m (alo, 2016). 2.2 data collection data used for this study was collected from temporary sample plots (tsps) of tectona grandis stands of different age series; 26, 23, 22, 16, 14 and 12 years specifically. a stratified random sampling technique was employed in this study. the six age series constitute the strata in the study area with a total land area of 66.5 hectare. hence, simple random sampling technique was used in allocating thirty six (36) tsps of 25x25 m size in the stands (six plots per age stratum). within each sample plot, the following tree growth variables were measured: merchantable height (m), stump diameter and diameter (cm) outside bark at breast height (i.e. ds and dbh measured at 0.3 m and 1.3 m above the ground level, respectively), a total number of one thousand nine hundred and nineteen (1, 919) trees were measured in all the thirty six randomly selected sample plots. chukwu and osho. /journal of tropical forestry and environment vol. 7, no. 02 (2017) 39-48 41 figure 1: map of omo forest reserve, nigeria 3. data analysis 3.1 model description and fitting procedure the available fitting data consists of measurements taken from trees located within different selected plots. in this study, least square method was used to fit data using the four candidate (nonlinear) functions (equations 1-4).the height-stump diameter models developed and tested in this study were the square, hyperbolic, modified logistic and exponential models. the tree height-stump diameter model formulated to express tree height (merchantable) as a function of stem diameter (stump). the models are in the following forms: 𝐻𝑡 = 𝑏0 + 𝑏1 ( 1 𝐷𝑠 ) 2 (finger, 1992; navroodi et al., 2016) (1) 𝐻𝑡 = 0.3 + 𝐷𝑠2 (𝑏0+𝑏1𝐷𝑠+𝑏2𝐷𝑠 2) (loetsch et al., 1973) (2) 𝐻𝑡 = 0.3 + 𝑏0 (1+𝑏1 −1 .𝐷𝑠−𝑏2 ) (huang et al., 1992; ahmadi 2013) (3) 𝐻𝑡 = 0.3 + 𝑏0. 𝑒 ( 𝑏1 𝐷𝑠+𝑏2 ) (ratkowsky, 1990; ahmadi, 2013) (4) where: ht = merchantable height (m) ds = stump diameter b0, b1 and b2 = regression parameters e= exponential 42 3.2 model evaluation and validation the evaluation of the candidate models was based on graphical and numerical analysis of the residuals which are; model with least values of the standard error of estimate (rmse), akaike information criterion (aic) and highest adjusted coefficient of determination (adj.r2) was selected as best. they are mathematically expressed as follows: 𝐴𝑑𝑗. 𝑅2 = 1 − (1−𝑅2)(𝑛−1) 𝑛−𝑝 (5) 𝑅𝑀𝑆𝐸 = √ ∑( 𝑌𝑖−�̂�𝑖 ) 2 𝑛 (6) 𝐴𝐼𝐶 = 𝑛ln(𝑅𝑆𝑆/𝑛) + 2𝑝 (7) where: �̅�𝑖 = arithmetic mean of the observed value 𝑌𝑖 = observed value of y for observation i �̂�𝑖 = predicted value i 𝑛=the total number of observations 𝑌𝑖 (trees) used in fitting the model 𝑝= the number of model fixed parameters 𝑅𝑆𝑆 = residual sum of square ln = natural logarithm. in addition, residual plots were carried out to check the error assumption. the significance of the parameter estimates was also observed. the overall best candidate model was validated using an independent data set of about 25% (392 trees) of the total data (1,919 trees) collected for this study. the ttest for paired samples was adopted as model validation method; a confidence level of p<0.05 was used for statistical significance. 4. results 4.1 data summary the model fitting data set covered a wide range. the mean, maximum and minimum of the measured variables are presented in the box and whiskers plot (figure 2 and 3). the distribution of stump diameter (ds) ranged from 7.67 to 48.97cm and ht ranged from 3.7 to 18.9 m2. the mean values and standard error (se) of stump diameter and merchantable height were displayed in the box plots (figure 2 and 3). the result of pearson’s product-moment correlation analysis between ht, ds and dbh (table 1) revealed that ds is highly and positively correlated with dbh (r=0.96). the result also shows that ht is positively correlated with ds with r value of 0.50. the graphical relation between the explanatory variable (ds) versus response variable (ht) was displayed in figure 4. the scatter plot (graph) showed a curvelinearly relationship between merchantable height and stump diameter of t. grandis in the study area. chukwu and osho. /journal of tropical forestry and environment vol. 7, no. 02 (2017) 39-48 43 mean = 22.0827 mean±se = (21.9332, 22.2322) min-max = (7.6704, 48.9656) ds (cm ) 5 10 15 20 25 30 35 40 45 50 55 figure 2: box and whisker summary statistics of tree stump diameter (ds) in cm. mean = 10.482 mean±se = (10.4282, 10.5358) min-max = (3.7, 18.9) ht (m ) 2 4 6 8 10 12 14 16 18 20 figure 3: box and whisker summary statistics of tree merchantable height (ht) in m. table 1: correlation matrix of tree growth variables. ds dbh ht ds 1 dbh 0.96* 1 ht 0.50* 0.52* 1 * correlation coefficient is significant at the 0.05 level (2-tailed), merchantable height (m), dbh=diameter at breast height (cm) and ds=stump diameter (cm). number of tree=1919 44 figure 4: relationship between merchantable height and stump diameter. 4.2 height-stump diameter models the models developed in this study was to estimate the present and future values of merchantable height at individual tree level for t. grandis stands in omo forest reserve, nigeria. the models were developed using individual tree merchantable height as dependent variable and stump diameter as independent variable. all parameters were found to be significant at the 5% level of probability. out of the four models fitted using ds as independent variable; the square function gave the least values of rmse (0.083) and aic (-7578.5) and the highest adj. r2 (0.314). however, the exponential function gave the highest values rmse (2.045) and aic (2,191.01) and least adj.r2 (0.224). figure 5 showed the graph of the residuals distribution against the predicted of height. 4.3 model validation thevalidation test result shows that observed value was not significantly different from the predicted value of the predicted at probability level of 0.05 (table 3). table 2: examined height-stump diameter models. functions parameters fit statistics b0 b1 b2 adj.r 2 rmse aic square 1.087 -29.393 0.314 0.083 -7578.5 hyperbolic 1 -0.982 0.936 0.300 1.942 2033.37 modified logistic 0.000005 0.000002 -0.392 0.273 1.979 2091.64 exponential 0.029 -2231.3 -403.04 0.224 2.045 2191.01 where: b0, b1, b2 = regression parameters adj.r2 = adjusted coefficient of determination rmse= root mean square error aic= akaike information criterion r² = 0.3041 0 5 10 15 20 0.0 10.0 20.0 30.0 40.0 50.0 60.0 m e rc h a n ta b le h e ig h t ( m ) stump diameter (cm) chukwu and osho. /journal of tropical forestry and environment vol. 7, no. 02 (2017) 39-48 45 figure 5: residual distribution against ht using square model. table 3: results of validation of square model using t test for paired sample. 5. discussion this study provided information on the stem diameter (ds and dbh) and merchantable height (ht) of tectona grandis stands in omo forest reserve (table 1 and figure 1-2). this study however, concerted effort towards estimating merchantable height at individual tree basis using stump diameter. a high positive bivariate correlation was observed between stump diameter and diameter at breast height. this implies that dbh increase with the increase in stump diameter. this result is similar to the reports of oyebade and onyambo, (2011), shamaki and akindele (2013) and chukwu et al. (2017) that diameter at breast height (dbh) and stump diameter (ds) are highly correlated. hence, to avoid co-linearity between the two growth variables (ds and dbh) as indicated by huang et al. (2003), only stump was selected as independent variable for developing models in this study. the principle of using stump diameter alone was to help forest managers obtain information on the original structure of a forest after exploitation either by legal or illegal activities within the forest. osho (1983), westfall (2010), özçelík et al. (2010), shamaki and akindele, (2013) and chukwu et al. (2017) upheld this method stating that,estimating tree growth variables after exploitation can only be possibly done through the stumps diameter, as tree stump is possibly the only tree part left after logging. the nonlinear ht-ds models fitted in this study were in square, hyperbolic, modified logistic and exponential functions form (equations 1-4, respectively). all parameters were found to be significant at the 5% level of probability. the criteria adopted for selecting the best model was through comparison of -8 -6 -4 -2 0 2 4 6 8 8 9 10 11 12 13 14 15r e si d u a l predicted function mean obs. mean pred. t value 𝛅2 obs. 𝛅2 pred. p value df remark square 94.87 94.81 1.648 265.68 263.98 0.376 391 ns where: 𝛅2 = variance, df= degree of freedom, ht = merchantable height (m), ns = not significant (p>0.05). numbers of tree = 392 46 adj.r2, rmse and aic which are standard ways of verifying models predictive ability as pointed out by huang et al. (2003), shamaki and akindele (2013) and navroodi et al. (2016). consequently, this study considered adj.r2, rmse and aic as evaluation criteria in the selection of models. the higher the adjusted r2 value the better the model, also the lower the rmse and aic the better the model. the efficiency of this procedure was confirmed by navroodi et al. (2016) and chukwu et al. (2017). based on the model evaluation results, the square model was selected out of the four nonlinear candidate models. the square model had the least values of; rmseand aic with the highest adj.r2. this result was similar to the reports of oyebade and onyambo (2011) that used nonlinear technique to develop height-diameter predictive equations for rubber (hevea brasilliensis) plantation in choba, port-harcourt, nigeria. however, the height-stump diameter models developed in this study showed low adj.r2 and high rmse except for the square function. this may be as a result of the large numbers of tree (1,527) used in this study as compared the 144 trees used by oyebade and onyambo (2011). however, okojie (1985) stated that, height–diameter equations are usually constructed from few samples. furthermore, popoola and adesoye (2012) and shamaki (2016) reported similar and/or low coefficients of determination (r2) for nonlinear model and selected the best model based on low error terms. in the graphical relationship between the residuals and estimated merchantable height obtained with the square function, displayed constant error variance was distributed on both in the positive and negative region of the x-axis (i.e. the estimated height values). this is desirable for a good model. this trend was similar to the findings of sánchez et al. (2003) and oyebade and onyambo (2011). furthermore, independent data set not used in the models calibration was used to validate the model. the paired t-test was used to test for significance between predicted and the observed merchantable height. the result showed a non-significant difference. this indicates that the developed htds model (square) was valid for estimating height of t. grandis stands in the study area. 6. conclusion this study revealed that tree growth characteristics can be estimated from stump diameter. hence, aid in the reconstruction of sizes of removed trees, which includes; describing the structure of a removed tree, creating historical records of past management activities, reviewing harvesting practices, assessing damage due to catastrophic events and establishing loss due to indiscriminate and/or illegal felling. this study concludes that, individual tree merchantable can be estimated from stump diameter using the square function in an event of indiscriminate and/or illegal felling in omo forest reserve, nigeria. furthermore, inclusion of other stump variables (stump basal area and stump height) as independent variables is recommended for further study. hence, stump diameter should be taken at several points above and below 0.3 m. acknowledgements appreciation goes to miss j.u. ezenwenyi, mr. j.u. nwachukwu, f.n. oganaand forest biometrics and remote sensing unit, department of forest resources management, university of ibadan, nigeria for technical and material support toward the success of this research work. chukwu and osho. /journal of tropical forestry and environment vol. 7, no. 02 (2017) 39-48 47 references adebagbo c.a. 1992. illegal felling: an environmental degradation activity (case study: sapoba forest reserve), proceedings of the 22nd annual conference of the forestry association of nigeria, 2nd – 7th november, kano, nigeria. ahmadi, k., alavi, s.j., kouchaksaraei, m.t. and aertsen, w. 2013. non-linear height-diameter models for oriental beech (fagusorientalislipsky) in the hyrcanian forests, iran, biotechnol. agron. soc. environ. 17(3): 431-440 alo, a.a. 2016. development of digital elevation models for omo forest reserve nigeria, forestry and allied natural resources disciplines in nigerian institutions: inputs for future solutions to dwindling forest estate in nigeria, proceedings of the 1st commonwealth forestry association (cfa) conference, nigeria chapter. 357-363 botkin, d.b., jamak, j. f. and wallis, j.r. 1972. some ecological consequences of a computer model of forest growth. journal of ecology, 60: 849-873. chukwu, o., dau, j.h. and ezenwenyi, j.u. 2017. crown-stump diameter model for parkiabiglobosabenth. species in makurdi, benue state, nigeria, journal of tropical forestry and environment. 7(1): 43-53. colbert, k.c., larsen d.r. and lootens, j.r. 2002. height-diameter equations for thirteen midwestern bottomland hardwood species, northern journal of applied forestry, 19: 171-176. emeghara e.e. 2012. forestry: a veritable tool for sustainable rural development in nigeria, international journal of agriculture and rural development. 15 (1): 953-957. evidence act. 1990. laws of the federation of nigeria 1990 chapter 112. http://www.nigerialaw.org/evidenceact.htm, accessed on 31august 2017. finger, c. a. g. 1992. fundamentos de biometriaflorestal. (fundamentals of forest biometrics) maria/brazil: ufsm/cepef/fatec, 269p. huang, s., titus, s.j. and wiens, d.p., 1992. comparison of nonlinear height-diameter functions for major alberta tree species, canadian journal of forest research, 22: 1297-1304. huang. s., yang, y. and wang, y. 2003. a critical look at procedures for validating growth and yield models. in: amaro, a., d. reed and p. soares (eds.). modelingforest systems. cab international. 123-214. ikuomola, a.d., okunola, r.a., and akindutire, a.f. 2016. criminality: illegal logging of woods in nigeria’s south-west forest belt, african journal of criminology and justice studies: 9 (1):114153. krisnawati, h., wang y. and ades, p.k. 2010. generalized height-diameter model for acacia mangiumwilld. plantations in south sumatra, journal of forest research, 7: 1-19. kurz, w.a., apps, m.j., webb, t.m. and mcnamee, p.j. 1992. the carbon budget of the canadian forest sector: phase 1. information report nor-x-326. edmonton, ab, canada: forestry canada, northwest region, northern forestry centre. loetsch f., zöhrer f., haller k. e. 1973. forest inventory, munich, blv verlagsgesellschaft: 469 p lumbres, i.r.c., lee, y.j., seo, y.o., kim, s.h., choi, j.k. and lee, w.k. 2011. development and validation of nonlinear height-dbh models for major coniferous tree species in korea, forest science and technology, 7, pp.117–125. navroodi, h., alavi, s.j., ahmadi, m.k. and radkarimi, m. 2016. comparison of different non-linear models for prediction of the relationship between diameter and height of velvet maple trees in natural forests (case study: asalem forests, iran), journal of forest science, 62, (2): 65–71. okojie, j.a. 1985. height-diameter model for taungya plantation of naucleadideriichi, journal of tropical forest resources, 75-83. osho, j.s.a. 1983. volume prediction from stump diameter for teak (tectonagrandisl.f.) in onigambari forest reserve. nigerian journal of forestry.13 (1-2): 53-56. 48 oyebade, b.a., onyambo, e. 2011. height-diameter predictive equations for rubber (heveabrasilliensis-a. jussmuell) plantation in choba, port-harcourt, nigeria, journal of agriculture and social research (jasr) 11(1): 1-11. özçelík, r, brooks, j.r., diamantopoulou, m.j. and wiant-jr, h.v. 2010. estimating breast height diameter and volume from stump diameter for three economically important species in turkey, scandinavian journal of forest research. 25: 32-45. parresol, b.r. 1992. bald cypress height-diameter equations and their prediction confidence intervals, canadian journal of forest research, 22:1429–1434. peng, c., zhang, l., and liu, j. 2001.developing and validating nonlinear height-diameter models for major tree species of ontario's boreal forest, northern journal of applied forestry, 1: 87-94. popoola, f.s. and adesoye, p.o., 2012. crown ratio models for tectonagrandis(linn. f) stands in osho forest reserve, oyo state, nigeria journal of forest science. 28(2): 63-67. sáncheza, c.a.l., varela, j.g., dorado, f.c., alboreca, a.r., soalleiro, r.r., gonzález, j.g.a. and rodríguez, f.s. 2003. a height-diameter model for pinusradiata d. don in galicia (northwest spain). annals of forest science, 60: pp. 237–245. shamaki, s.b. and akindele, s.o. 2013. volume estimation models from stump diameter for teak (tectonagrandislinn f.) plantation in nimbia forest reserve, nigeria, journal of environmental science and water resources, 2(3): 089 094 shamaki, s.b., akindele, s.o. isah, a.d. and mohammed, i. 2016. height-diameter relationship models for teak (tectonagrandis) plantation in nimbia forest reserve, nigeria, asian journal of environment and ecology 1(1): 1-7. soares, p. and tome, m. 2002. height–diameter equation for first rotation eucalypt plantations in portugal, forest ecology and management. 166: 99–109. spurr, s.h. 1952. forest inventory, new york, usa: the ronald press company. 476p. vanclay, j.k. 1994. modelling forest growth and yield: applications to mixed tropical forests, cab international, oxon, u.k., 312 p. westfall, j.a. 2010. new models for predicting diameter at breast height from stump dimensions, north. j. appl. for. 27(1): 21-27 zhang l. 1997. cross-validation of non-linear growth functions for modeling tree height-diameter relationships. annals of botany, 79: 251-257. chapter 5 48 solar radiation alters toxicity of carbofuran: evidence from empirical trials with duttaphyrnus melanostictus m.r.wijesinghe*, b.a.d.m.c. jayatillake and w. d. ratnassoriya department of zoology, university of colombo, colombo 03. date received: 04-04-2011 date accepted: 12-09-2011 abstract in the present study we investigated the potential of natural solar radiation to alter the toxicity of a commonly used carbamate pesticide, carbofuran, on tadpoles of the common asian toad duttaphrynus melanostictus. a single exposure trial was conducted over 96 hrs with three concentrations (150, 250 and 500 µgl-1) of photo-irradiated and non-irradiated carbofuran. results show that photo-irradiation markedly reduced the toxicity of carbofuran as evident by its effects on three end points, i.e. mortality, growth and swimming activity. the mortality of tadpoles exposed to irradiated carbofuran was significantly lower than those exposed to the non-irradiated pesticide. both treatment and control tadpoles showed a hormetic response for mortality. tadpoles in irradiated tanks were also larger and more active than those in the control tanks. photo-altered toxicity was evident at all three tested concentrations. the results of this study therefore signals caution when directly linking results of empirical trials to field scenarios and highlight the necessity to evaluate toxic effects of compounds under variable environmental conditions. keywords: carbofuran, duttaphrynus melanostictus, photo-degradation, tadpoles, toxicity *correspondence: e-mail-mayuri@zoology.cmb.ac.lk tel+ 94 07144 6277 issn 2235-9370 print/ issn 2235-9362 online ©2011university of sri jayewardenepura journal of tropical forestry and environment vol. 01, no. 01 (2011) 48-55 49 1. introduction pesticides are one of the major causes of water pollution and scores of toxicological studies have repeatedly provided evidence implicating that these harmful contaminants are one of the potential causes for the decline of many faunal species. the majority of the standard toxicity tests, while generating a wealth of invaluable information on lethal and sublethal toxic effects observed under controlled conditions, may not directly reflect field scenarios. in recent years increasing attention has been paid to the importance of the non-biological mechanisms that assist in the breakdown of environmental contaminants (e.g. iesce et al., 2005). one such mechanism is photo-degradation facilitated by uv radiation. with photodegradation occurring in the field, aquatic organisms will most likely be exposed to the photolytic byproducts as opposed to the original compound. many studies have been carried out on degradation pathways and mechanisms, kinetics, and the characterization of such by-products (iesce et al., 2005). accordingly, some have demonstrated that such degradation mechanisms result in the formation of byproducts that may differ from the original substance in terms of environmental persistence and toxicity (kim et al., 2007, campanella et al., 2006, blaustein and belden, 2003; oris and giesy, 1987), although information is lacking for many substances and test organisms. sri lanka is an agricultural country where pesticides are heavily used. these substances are typically washed into water bodies in the form of surface runoff exposing fish and other aquatic organisms to these harmful substances. nevertheless as sri lanka is located close to the equator at 6º55’n, the country receives intense solar radiation (with a uv index of 11 and above) for at least eight months of the year (who 2009). therefore photo-degradation processes could be expected to assume an important role in the biodegradation of pesticide contaminants. this paper focuses on investigating the potential of natural solar radiation to alter the toxicity of the carbamate pesticide, carbofuran, which is used widely for the control of rice pests (tennakoon et al., 2009). it was considered particularly important to test the effect of solar radiation on the alteration of toxicity of carbofuran because its peak absorbance (ë max 277– 283 nm) falls within the uv range of the solar spectrum making it highly photo-degradable (iesce et al., 2005). the toxic effects of carbofuran were tested on tadpoles of the bufonid duttaphrynus melanostictus (asian common toad) (schneider, 1799). 2. methodology 1.1. test organisms and pesticide concentrations d. melanostictus tadpoles of gosner stages 24-25 were collected from three house ponds in the colombo district in sri lanka where no pesticides were used. collection of larvae from widely separated areas ensured that the larvae collected were from different populations. the larvae were identified as those of d. melanostictus by their external morphology and teeth arrangement as described by kirtisinghe (1995). a commercial preparation of carbofuran (curater 3g, hayleys agro products ltd. colombo, sri lanka) was used to prepare low, mid and high test concentrations (150, 250 and 500 µgl-1). as no published information was available on field levels of carbofuran, test concentrations used in the present study were based on empirical trials conducted elsewhere (e.g. bretaud et.al., 2002). wijesinghe et al./journal of tropical forestry and environment vol. 01, no. 01 (2011) 48-55 50 1.2. experimental procedure a 1000 mgl-1 aqueous stock solution of carbofuran was placed in a glass beaker which was irradiated by exposing it to natural solar radiation for five hours between 1000 1500 hrs on a day with a clear sky. as coimbatore, india (11ºn), receives 50 % of the uv radiation between 1000 1445 hrs (balasaraswathy, 2004) the pesticide was irradiated during this period. the uv index at the site of irradiation was measured using a uv index meter (chaney tm uv index meter, china) every 30 mins. immediately after, the three pesticide concentrations were prepared using the irradiated stock solution of the pesticide and distilled water. the larvae were housed in glass tanks (n=18 per tank and n=56 per treatment/control) filled with tap water allowed to age for chlorine to dissipate. appropriate volumes of the pesticide were added to the tanks and the water was mixed using a glass rod. eighteen tadpoles were then randomly assigned to each tank. a separate set of tanks where tadpoles were exposed to similar concentrations of the non-irradiated pesticide served as the control. each of the three concentrations of the treatment and control were conducted in triplicate. the experiment was performed as a single exposure trial, which was maintained over the standard 96 hrs. a similar experimental procedure has been followed by zaga et al., (1998) to investigate photo-altered toxicity of carbaryl on amphibian larvae. the trial was conducted at room temperature (26-28°c) and inside a dark room. three fluorescent tubes that do not emit uv radiation (f74 daylight 58w, tungsten 5", hungary; zero emissions were confirmed by the uv meter) were used as artificial sources of light. the lights were switched on from 0600 – 1800 hrs throughout the experimental period to simulate the natural photoperiod (approximately 12 hours light and 12 hours darkness). the larvae were fed once a day with fish food pellets (46 ± 4 mg per day) (blue aqua pets, godagama, sri lanka) throughout the trial. all tanks were aerated with a constant flow rate ensuring a continuous supply of oxygen for the larvae. water temperature, ph (water temperature and ph meter, hm-30v, toa electronics ltd, tokyo, japan) and dissolved oxygen (dissolved oxygen meter (hanna hi 9142, romania) were recorded on day 2 and day 4. there were no significant differences in the experimental conditions between the treatment and control tanks as revealed by two sample t-tests performed separately on each parameter i.e. temperature (t33 = -1.07, p>0.05), ph (t26 = -1.92, p>0.05) and dissolved oxygen levels (t 33 = -1.15, p>0.05). mortality in each tank was monitored daily and body length measurements, staging (according to gosner, 1960) and recording of swimming activity were conducted on day 1 and day 4. swimming activity was assessed using a protocol described by sumanadasa et al. (2008). qualitative assessments were made of the abnormalities observed in the tadpoles. 3. results this study reveals that irradiation of carbofuran by natural solar radiation (at an intensity of uv index 10), markedly alters its toxicity and therefore causes less damage to the exposed tadpoles. mortality of larvae exposed to non-irradiated carbofuran was significantly higher than that observed in those exposed to irradiated carbofuran over the experimental period of four days (two-way anova: uv factor f= 78.44, p<0.0001: concentration f= 79.62, p<0.0001: interaction f= 11.21, p <0.002). this trend journal of tropical forestry and environment vol. 01, no. 01 (2011) 48-55 51 was apparent for all three tested doses of carbofuran with mortality in tanks with irradiated carbofuran being reduced by 15 %, 29 % and 7 % in 150, 250 and 500 µgl-1, respectively (figure 1). in both photoirradiated and non-irradiated tanks the highest mortality levels were recorded from 250 µgl-1carbofuran, with levels observed at 150 and 500 µgl-1 being lower, giving a bell shaped dose-response. closer examination of mortality patterns revealed that mortality levels also varied with time (figure 2). in both treatments and the controls there was a gradual increase in the rate of mortality (number of tadpoles dead per day) until the day 3 after which mortality rates declined. figure 1: mortality (mean + s.e.) of d. melanostictus larvae exposed to three concentrations of sunlight irradiated and non-irradiated carbofuran at the end of a four-day single exposure experiment. figure 2: variation in mortality rates (mean + s.e.) (% of tadpoles dead per day) in d. melanostictus larvae exposed to solar irradiated and non-irradiated carbofuran over a four day single exposure experiment. as with mortality, irradiation reduced the potential of carbofuran to cause any growth impairment. by the end of the trial larvae exposed to photo-irradiated carbofuran were larger in size than those exposed to non-irradiated carbofuran (table 1). a two sample t-test was used to examine if these differences in size between larvae exposed to irradiated and non –irradiated pesticides, were significant. the results confirmed that there was no significant difference in the initial lengths of larvae among control and treatment tanks (t15 ± -0.16, p>0.05). however, the final body lengths of larvae at the end of four day experimental period in treatment tanks were significantly higher than those in the control tanks (t9 = -5.12, p<0.05). wijesinghe et al./journal of tropical forestry and environment vol. 01, no. 01 (2011) 48-55 p er ce nt ag e cu m ul at iv e m or ta li ty 150 250 500 with uv without uv concentration concentration 150 + uv 250 + uv 500 + uv 150 + uv 250 + uv 500 + uv m ea n % m or ta li ty 1 2 3 4 day 25 20 15 10 5 0 µg/1 52 table 1: mean body lengths (± s.e) of d. melanostictus larvae exposed once to low, mid and high levels of non-irradiated and photo-irradiated carbofuran for four days. an interesting pattern was evident (figure 3) such that the activity of larvae in control tanks (with non-irradiated pesticide) markedly increased at the beginning of the exposure and considerably declined by day 4. in contrast, in the treatment tanks, although the larval activity did not increase initially, by day 4 the activity of the tadpoles was higher than that of the controls. in both the control and treatment tanks, the variation in swimming activity across the three concentrations followed a similar pattern. the highest mean activity was shown by the larvae in 500 µgl-1 of non-irradiated carbofuran, while the lowest was obtained for 250 µgl-1 photo-irradiated carbofuran. two sample t-tests conducted on the results of swimming activity days 1 and 4 shows that there is a significant difference in larval activity patterns between control and treatment tanks (day 1 t 11 = 11.43, p<0.05: t 10 = -2.49, p<0.05). furthermore rough assessments of the number of tadpoles with abnormalities showed that while around 20 % of the tadpoles exposed to non-irradiated carbofuran suffered from swollen heads and irregular swimming, only about 5 % of tadpoles exposed to irradiated carbofuran showed such abnormalities. figure 3: swimming activity levels (per individual for 10 minutes) of d. melanostictus larvae exposed to different concentrations of non-irradiated and photo-irradiated carbofuran in the initial and final days of the experiment. journal of tropical forestry and environment vol. 01, no. 01 (2011) 48-55 concentration 150 + uv 250 + uv 500 + uv 150 + uv 250 + uv 500 + uv µg/1 day 7 6 5 4 3 2 1 0 1 4 n um be r of s w im m in g ev en ts concentration body lengths of control tadpoles body lengths of treated tadpoles (non-irradiated carbofuran) (photo irradiated carbofuran) (mm) (mm) initial final initial final 150µg1-1 3.40 4.87 3.42 5.50 ±0.04 ±0.13 ±0.06 ±0.06 250µg1-1 3.42 4.78 3.41 5.39 ±3.41 5.26 3.41 5.58 500µg1-1 ±0.03 ±0.27 ±0.06 ±0.04 53 4. discussion the present study demonstrates that natural solar radiation has the potential to alter the toxicity of the carbamate pesticide carbofuran. this was evident from empirical trials that assessed the toxicity of carbofuran on tadpoles of the asian common toad duttaphrynus melanostictus. the reduction in toxic effects was noted with low, mid and high concentrations of carbofuran and with respect to three end points namely mortality, growth and activity of the tadpoles. for example, mortality observed in 250 µgl-1 of the photo-irradiated carbofuran (29 %) was lower than that which occurred when the pesticide was not irradiated (55 %). trends in mortality were similar with both irradiated and non-irradiated carbofuran with mid concentrations resulting in higher levels of morality suggesting a hormetic response (calabrese and baldwin, 2002) commonly observed with endocrine disruptors, althoughthe exact mechanisms are poorly understood. tadpoles exposed to irradiated carbofuran were also comparatively larger than those in control tanks. the activity patterns of the larvae over the experimental period also changed as a result of irradiation of the pesticide before exposure. morphological deformities observed with non-irradiated carbofuran were more frequent than in those exposed to the irradiated pesticide. as far as we are aware this is the first study that has demonstrated a reduction in toxicity of carbofuran by natural solar radiation. considering other agrochemicals, gupta et al., 2002 has shown reduced toxicity of the herbicide atrazine on the metolachlor bacterium vibrio fischeri due to solar-irradiation. they have further demonstrated that in rivers and bays toxicity levels are negatively correlated with light intensity. carbofuran is generally degraded in water by chemical hydrolysis, microbial decomposition and photolysis (national research council of canada, 1979) and has a half life of 27 days at 25°c and ph 7 (dpr, 2002). base-catalyzed hydrolysis results in the formation of the carbofuran-phenol and is recognized as the major degradation pathway of carbofuran in both water and sediment (brahmaprakash et al., 1987; seiber et al. 1978; talebi and walker, 1993; yu et al. 1974). carbofuran is also highly photodegradable (raha and das, 1990; deuel et al., 1979); photomodification in water occurring as a result of ultraviolet light which produces high-energy photons (larson, 1990). with regard to carbofuran, there is considerable potential for degradation from solar radiation because its absorbance is within the uv range (iesce et al., 2005). it has been reported that photo-degraded products of carbofuran include 2,3-dihydro-2,2dimethylbenzofuran-4,7-diol and 2,3-dihydro-3 keto-2,2 dimethyl benzofuran-7-yl carbamate (or 3-ketocarbofuran) (raha and das, 1990). the toxicities of these by-products have not been previously evaluated. the lethal effects of carbofuran are mainly attributed to direct inhibition of acetylcholine esterase activity at central cholinergic synapses and neuromuscular junctions and the ultimate cause of death has been identified as respiratory failure (hayes et al., 1991). the reduction in mortality observed in the present study suggests that that the by-products formed as a result of photodegradation may not be inhibiting acetylcholine esterase to the same degree as the carbofuran-phenol that is produced as a result of hydrolysis and hence is probably less toxic to the tadpoles. in sharp contrast to the observations made in the present study, trials with another carbamate carbaryl on x. laevis and h. versicolor tadpoles (zaga et al., 1998) and rana sphenocephala (boone and bridges, 2003) have shown that solar radiation enhances toxic effects. sarmah et.al., (2004) has reported that photodegradation of pesticides is influenced by the intensity and duration of the exposure to sunlight. the radiation levels used in the study with carbaryl (4 ì w/cm2) were, however, much lower than the wijesinghe et al./journal of tropical forestry and environment vol. 01, no. 01 (2011) 48-55 54 ambient levels recorded for sri lanka (189 w/m2), which was used in the present study. thus it is very likely that further degradation of the toxic intermediate by-products into milder compounds occurs under high uv intensities. additional causes of contradictory results may reflect differences in species tolerance, nature of exposure to the chemical (e.g. duration and frequency) and variations in pharmacokinetics of the pesticide under consideration. in nature the effect of solar radiation may also be altered by other factors. for instance, it has been reported that the amount of dissolved organic matter in water tends to slower the rates of photolysis of pesticides making them more persistent in the environment (e.g. bachman and patterson 1999). because of the complexity in natural ecosystems, where a combination of factors is often responsible for the observed effects in organisms, scientists reiterate that laboratory investigations may not directly simulate field conditions. while recognizing the importance of empirical trials in assessing toxicity, the present study signals a note of caution when directly extrapolating results of such trials to field scenarios. this study also emphasizes the necessity to investigate toxic effects under variable environmental conditions as this would substantially increase the applicability of results generated from laboratory trials to field situations. acknowledgement we wish to acknowledge the university of colombo, sri lanka, for financial assistance and laboratory facilities. we are also grateful to mr. j. a. r. c. jayakody and ms. sriyani abeyratne for their assistance. references bachman, j. and patterson, h.h. (1999) photodecomposition of the carbamate pesticide carbofuran : kinetics and the influence of dissolved organic matter. environmental science & technology 33: 874881 balasaraswathy, p. (2004). sunlight in india, skin care n cure. national conference of indian association of dermatology, venereology and leprosy, mumbai. available online at http:// www.skincarencure.com/sunlight.htm [ accessed on 10th march 2009] blaustein, a. r. and belden, l. k. (2003) amphibian defences against ultraviolet-b radiation. evolution and development 5:89–97. boone, m. d. and bridges, c. m. (2003) the interactive effects of uv-b and insecticide exposure on tadpole survival, growth and development. biological conservation 113:49–54. brahmaprakash, g.p., panda, s. sethunathan, n. (1987) relative persistance of hexachlorocyclohexane, methyl parathion, and carbofuran in an alluvial soil under flooded and non-flooded conditions. agricultural ecosystems and the environment 19:29-39. bretaud, c., saglio, p., saligaut, c., auperin, b. (2002) biochemical and behavioral effects of carbofuran in gold fish (carassius auratus). environmental toxicology and chemistry. 21, 175–181. calabrese, e.j. and baldwin, l.a., (2002) defining hormesis. human and experimental toxicology 21: 91–98. campanella, l., vitaliano, r. and chimica, a. (2006) toxicity reduction following h2o2/tio2photocatalyzed reaction and comparison with h2o2-photolytic reaction. annali di chimica roma 97:123 – 134. journal of tropical forestry and environment vol. 01, no. 01 (2011) 48-55 55 deuel, l.e., price, j.d., turner, f.t. and brown, k.w. (1979) persistence of carbofuran and its metabolites, 3-keto and 3-hydroxy carbofuran, under flooded rice culture. journal of environmental quality 8(1):23-26. dpr (2002) pesticide chemistry database. environmental monitoring branch. department of pesticide regulation, california. available online at http://www.cdpr.ca.gov/docs/pur/purmain.htm [accessed 5th march 2009] gosner k. l. (1960) a simplified table for staging anuran embryos and larvae with notes on identification. herpetological science 16: 183-190. gupta, g. lin, y. j., karuppiah, m., shaw, a. (2002) effect of simulated sunlight on atrazine and metolachlor toxicity of surface waters. ecotoxicology and environmental safety 43:(1) 35-37. hayes, w. j., laws, e. r., baron, r. l. (1991) carbamate insecticides: handbook of pesticide toxicology, academic press, new york. p.3-6. iesce, m.r., della greca, m., cermola, f., rubino, m., isidori, m. and pascarella, l. (2005) transformation and ecotoxicity of carbamic pesticides in water. environmental science and pollution research 13(2):105-109. kim, j., cho, i., zoh, k., choi, k., (2007) assessing the microbial toxicity of pentachlorophenolcontaminated water after treatment with uv radiation and tio2 photocatalyst. journal of hazardous materials 148: 281-286. kirtisinghe, p. (1955) the amphibian of ceylon .1st edition. colombo, charles circus. larson, r.a. (1990) sensitized photo decomposition of organic compounds found in illinois waste waters. university of illinois, institute for environmental studies, urbana, illinois. national research council canada. (1979) carbofuran: criteria for interpreting the effects of its use on environmental quality. publication # nrcc 16740, ottawa. oris, j. t. and giesy, j. p. (1987) the photo induced toxicity of polycyclic aromatic hydrocarbons to larvae of the fathead minnow (pimephales promelas). chemosphere 16:1395–1404. raha, p. and das, a.k. (1990) photodegradation of carbofuran. chemosphere 21:99–106. sarmah, a. k., müller, k. and ahmad, r. (2004) fate and behaviour of pesticides in the agroecosystem— a review with a new zealand perspective. australian journal of soil research 42(2):125-154. seiber, j.n., catahan, m.p. and barril, c.r. (1978) loss of carbofuran from rice paddy water: chemical and physical factors. journal of environmental science and health 13(2):131-148. sumanadasa, d.m.,m. r. wijesinghe and w. d. ratnasooriya 2008 effects of diazinon on larvae of the asian common toad bufo melanostictus, schneider 1799). environmental toxicolology and chemistry. 27, 2320-2325. talebi, k. and walker, c.h. (1993) a comparative study of carbofuran metabolism in treated and untreated soils. pesticide science 39:65-69. tennakoon, s., perera, b. and haturusinghe, l. (2009) intentional poisoning cases of animals with anticholinesterase pesticide-carbofuran in sri lanka. legal medicine 11:500-502. who (2009) ultraviolet radiation and the intersun programme. available online at http:// www.who.int/uv/intersunprogramme/activities/uv_index/en/index3.html [accessed 2nd march 2009]. yu, c.c., booth, gary, m., hansen, dale j. and larsen, j.r. (1974) fate of carbofuran in a model ecosystem. journal of agriculture and food chemistry 22(3):431-434. zaga, a., little, e.e., rabeni, c.f. and ellersieck, m.r. (1998) photoenhanced toxicity of a carbamate insecticide to early life stage anuran amphibians. environmental toxicology and chemistry 17(12):2543–2553. wijesinghe et al./journal of tropical forestry and environment vol. 01, no. 01 (2011) 48-55 80 deriving tree crown distributions from diameter at breast height ogana f.n.1*, dau j.h.2 1department of social and environmental forestry, university of ibadan, nigeria 2department of forest production and products, federal university of agriculture, makurdi, nigeria date received: 24-11-2018 date accepted: 25-05-2019 abstract the distribution of crown diameter is important for assessing crown social class, monitoring forest health and wildlife management. however, the direct measurement of crown diameter is relative difficult, and as such, it is often predicted from diameter at breast based on a simple relationship. therefore, in this study, the crown diameter distribution of parkia biglobosa was derived from dbh using weibull and loglogistic functions. a total of 284 trees were measured from parkia biglobosa plantation in makurdi, nigeria. four methods were used for weibull distribution including maximum likelihood (mle), moments, percentiles and cumulative distribution function regression (cdfreg). mle and cdfreg were used for log-logistic function. transformation technique was used to transform the dbh to crown distribution based on a simple allometric relationship between the variables. kolmogorov-smirnov (dn), cramer-von mises statistic (w2) and reynolds error index (ei) were used to assess the derived crown diameter distribution. the result showed that the underlying diameter distribution followed weibull and log-logistic distributions. the fitted allometric equation was of the form: . mle and cdfreg were the best methods for weibull and log-logistic functions, respectively. the dn, w2 and ei were 0.071, 0.0265 and 0.3434, respectively for mle; and 0.0931, 0.0367 and 0.4171, respectively for cdfreg. in all methods, the observed and derived crown distributions were not significant at 20% (dα=0.339). thus, given the diameter distribution, the tree crown distribution of parkia biglobosa can be derived. this would be useful for determination of the crown social class. keywords: crown diameter, crown distribution, log-logistis, parkia biglobosa, weibull 1. introduction tree size distribution remains one of the most researched areas in forestry. it forms the basis for analysing the structure, volume production, value and even growth of forest stand (gorgoso-varela and rojo-alboreca, 2014). one easily measured variable frequently used in size distribution is diameter at breast height i.e., 1.3 m above the ground (hereafter referred to dbh). it correlates with other tree variables that are difficult to measure, e.g. height, volume, biomass, crown diameter etc. (west, 2015). several distribution functions have been applied at different times to describe the structure of forest stand using dbh as impute variable. some of these functions include beta, gamma, johnson’s sb, logit-logistic, lognormal and weibull distributions. the weibull distribution has been consistently used in forestry because of its simplicity, relative flexibility, ease of parameter estimation and computation of proportion of trees in diameter class (burkhart and tomé, 2012). beside dbh, there are different alternatives used for size distribution, such as height, basal area, tree volume, crown diameter and crown area (mehtatalo, 2013). if for example, the tree size specifies tree height, then the underlying distribution is called height distribution. *correspondence: fn.ogana@ui.edu.ng tel: +23 47037679328 issn 2235-9370 print/issn 2235-9362 online ©2019 university of sri jayewardenepura doi: https://doi.org/10.31357/jtfe.v9i1.3954 https://doi.org/10.31357/jtfe.v9i1.3954 ogana and dau /journal of tropical forestry and environment vol. 9, no. 01 (2019) 80-88 81 it could be basal area distribution, volume distribution, crown area or crown diameter distribution. mirzaei et al. (2016) modelled the frequency distributions of crown area, diameter and height of quercus persica stands in iran. chuckwu et al. (2018) used the weibull distribution to describe the crown diameter distribution in the natural stand of shasha forest reserve, nigeria. crown diameter is the “average of the widest axis of the crown and its perpendicular axis” (zarnoch et al., 2004). its distribution is relevant to both forest and wildlife managers. the larger the tree crown diameter, the more foliage for photosynthesis; in consequence, a more potential for carbon fixation (zarnoch et al., 2004). also, larger tree crowns are important for bird nest and perching (deng et al., 2003). tree crown is a good indicator of forest health because it shows the first symptom of deterioration when either natural or anthropogenic factors impact a forest (adesoye and ezenwenyi, 2016; kershaw et al., 2017). in addition, crown diameter is a key variable for computing crown surface area, volume (van laar and akca, 2007 p 96), canopy cover (gill et al., 2000) and crown profile analysis (marshall et al., 2003). to the wildlife manager, a forest with larger crowns could affect the abundance and distribution of fauna species, especially the herbivores. because low light penetration to the forest floor means less grasses and shrubs for the herbivores (chukwu et al., 2018). the measurement of tree crown diameter remains a major challenge to foresters, especially in forest stand with contiguous canopy and irregular edges (gering, 1995; van laar and akça, 2007). in view of this, crown diameter is obtained as photo-derived variable from remote sensing (gering, 1995). furthermore, foresters have also relied on the ability to predict crown diameter from dbh/stump diameter through a simple linear relationship (e.g. sonmez, 2009; adesoye and ezenwenyi, 2014; raptis et al., 2018 etc.). adesoye and ezenwenyi (2014) developed a crown diameter-dbh prediction model for tectona grandis linn. in omo forest reserve using a simple linear equation. recently, chukwu et al. (2017) used a simple linear relationship to predict crown diameter from stump diameter of parkia biglobosa benth. crown diameter-dbh relationship can be used to determine tree spacing, stand density, basal area per ha, thinning regimes etc. (hemery et al., 2005). mehtatalo (2013) introduced the idea of transformation in forestry. it involves changing from one tree size distribution to another. one major application of transformation is that it helps in the formulation of diverse distributions based on allometric relationships of trees (mehtatalo, 2013). transformation could be from diameter to crown diameter, diameter to height, diameter to basal area, or diameter to volume; in so far there is a functional relationship between the variables. this is an important tool that can be used to predict size distribution for variables that are difficult to measure. therefore, the main objective of this study was to derive tree crown distribution from diameter at breast height using transformation. 2. methodology 2.1 data the data were obtained from the parkia biglobosa plantation in makurdi, nigeria. its lies between latitudes 7o21/ and 8o0/ n and longitudes 8o21/ and 9o0/ e of benue state, nigeria and occupies an area of 7,978 km2 (chukwu et al., 2017). a total of 284 trees were measured on nine temporary sample plots (tsps) of 1ha size. diameter at breast height (dbh), height and crown diameter (cd) were measured to an accuracy of 0.1 cm, 0.1 m and 0.3 m, respectively. crown diameters were measured as the linear distance between edges of the tree crown in a north-south and east-west direction. the average value of northsouth and east-west measures was taken as the crown diameter. the descriptive statistics of the inventoried data is presented in table 1. 82 table 1: descriptive statistic of data set. tree variables mean max min standard deviation dbh (cm) 40.45 95.43 14.60 15.00 height (m) 6.85 17.80 2.11 2.07 crown diameter (m) 6.64 15.10 2.80 2.10 ba (m2) 0.15 0.72 0.02 0.11 cpa (m2) 38.13 179.08 6.16 25.17 volume (m3) 0.011 0.360 4.6x10-5 0.038 cpa=crown projection area. 2.2 transformation of tree dbh to crown diameter distribution let d and cd be diameter at breast height (dbh) and crown diameter, respectively. and the dbh data is assumed to follow the 2-parmeter weibull and log-logistic distributions. their cumulative distribution functions (cdf) are expressed as: weibull cdf, (1) log-logistic cdf, (2) the crown diameter-dbh relationship is given as linear (3) making d in equation (3) the subjection of the equation gives (4) substituting d in equation 1 with equation 4 gives the distribution of tree crown diameter (5) similarly, substituting equation (4) into equation 2 yielded the transformed log-logistic tree crown diameter expressed as: (6) where; and =the shape and scale parameters of the weibull and log-logistic distributions; a and b=the regression parameters. the fit of the transformed dbh to crown distribution were compared with the observed crown distribution to ascertained the adequacy of the method. 2.3 fitting methods four methods were considered for estimating the parameters of the weibull function including maximum likelihood, moment, percentiles (40 and 82) (bailey and dell, 1973) and cdf regression (cao, 2004). maximum likelihood and cdf regression methods were used for the log-logistic distributions. distributions were fitted in r (r core team, 2017). kolmogorov-smirnov (dn), cramer-von mises statistic (w2) and reynolds error index (ei) were used to assess the goodness of fit of the derived crown ogana and dau /journal of tropical forestry and environment vol. 9, no. 01 (2019) 80-88 83 diameter distribution. the smaller the fit indices are, the better the distribution. also, the fits from the different methods were tested with the kolmogorov-smirnov test at 20% significant level (dα). the null hypothesis (h0) is that the observed and estimated/derived distributions are not significant. thus, h0 is rejected when dn>dα. (7) (8) (9) (10) where; supx=supremum value for x f(xi)=cumulative frequency distribution observed for the sample xi (i =1, 2, …, n) f0(xi)=probability of the theoretical cumulative frequency 3. results and discussion 3.1 fitted diameter distributions the suitability of weibull and log-logistic distributions in describing the diameter distributions of parkia biglobosa was first assessed. this was done to ascertain the claim that the underlying diameter distribution followed the weibull and log-logistic distributions. the results showed that log-logistic fitted with mle and cdfreg had the smallest dn, w 2 and ei values (table 2). however, no significant difference was observed between predicted and observed diameter distribution for all methods at 20% level based on dα test (0.118). thus, all methods can be regarded as equally good and that the underlying diameter distribution followed the weibull and log-logistic distributions. cao (2004) commented on the advantages and disadvantages of some of these methods, especially the methods for fitting weibull distributions. the author reported that cdf-reg was the most preferred method for the weibull distributions. the mle has be found to produce consistent result and provides a means of estimating the standard error of the parameter estimate compared to other methods, but it computation procedure can be laborious (nord-larson and cao, 2006; mehtatalo, 2013). the method of moment and percentiles have also been applied to estimate the parameters of the weibull distributions with some level success including zhang et al. (2003), cao (2004), gorgoso et al. (2007), carretero and alvarez (2013) etc. the graph of the observed and weibull distributions fitted with mle, moments, percentiles and cdf-reg is presented in figure 1. while that of log-logistic fitted with mle and cdf-reg is shown in figure 2. the performances of the estimation methods were relatively the same for the two distributions. both weibull and log-logistic distributions approximate the observed tree diameter distribution of parkia biglobosa. table 2: fitted weibull and log-logistic to the diameter distributions of parkia boglobosa. distributions methods fit indices dn w 2 ei weibull cdf reg 0.0675 0.0590 1.8349 percentiles 0.0839 0.0654 1.8400 moments 0.0754 0.0721 1.9121 mle 0.0736 0.0750 1.9219 log-logistic mle 0.0358 0.0186 0.9943 84 cdf reg 0.0441 0.0190 1.0443 dα=0.118 figure 1: observe and fitted weibull distribution using different methods to the dbh data. figure 2: observe and fitted log-logistic distribution using different methods to the dbh data. 3.2 fitted derived crown distributions the fitted weibull and log-logistic distributions and the established crown diameter-dbh relationship were used to derived the tree crown distribution vis-à-vis the different estimation methods. the fitted simple linear crown diameter-dbh relationship was of the form: ; with adjusted coefficient of determination (r2adj) and root mean square error (rmse) of 0.609 and 1.182, respectively. the results of the transformed tree diameter to crown distributions are presented in table 3. the weibull distribution fitted with mle and moments were more suitable than percentiles and cdf reg methods. the kolmogorov-smirnov (dn), cramer-von mises (w 2) and error index (ei) were 0.071, dbh (cm) r e la ti v e f re q u e n c y dbh (cm) r e la ti v e f re q u e n c y ogana and dau /journal of tropical forestry and environment vol. 9, no. 01 (2019) 80-88 85 0.0265 and 0.3434, respectively for mle and 0.0781, 0.0305 and 0.3793, respectively for moments. in the case of log-logistic, the cdf reg was better than mle. its dn, w 2 and ei were 0.0931, 0.0367 and 0.4171, respectively. generally, the value of ei ranged between 0 (perfect match) and 2 (mismatched) (mehtatalo, 2017). the ei value of the methods considered for weibull and log-logistic distributions were within 0 > ei < 1 (i.e., < 0.5). this shows that the derived crown distribution matched the observed crown distribution of parkia biglobosa. the kolmogorov-smirnov test also shows no significant difference between the derived crown distribution and observed distributions at 20% level (0.339) for all methods. table 3: fitted weibull and log-logistic to the derived crown distributions. distributions methods parameters fit indices a b α β dn w 2 ei mle 2.521 0.099 2.839 45.256 0.0710 0.0265 0.3434 weibull moments 2.521 0.099 2.932 45.178 0.0781 0.0305 0.3793 percentile 2.521 0.099 2.886 43.385 0.1083 0.0357 0.4008 cdf reg 2.521 0.099 3.029 43.628 0.1131 0.0400 0.4462 log-logistic cdf reg 2.521 0.099 4.445 37.803 0.0931 0.0367 0.4171 mle 2.521 0.099 4.706 37.804 0.1055 0.0442 0.4687 dα=0.339 the graphs of the derived tree crown distributions resulting from different estimation methods are shown in figure 3 and 4. the graphs showed the relative cumulative distribution of trees per 1 m crown diameter class. the shape of the derived tree crown distribution (dash line) followed the observed distribution (thick line). this shows the effectiveness of transformation technique (cd-dbh transformation). thus, given an assumed diameter distribution, the tree crown distribution of parkia biglobosa can be derived. however, mehtatalo (2013) asserted that no randomness is assumed with the transformation technique. this implies that tree crown diameter depends on diameter at breast height (dbh) deterministically according to the simple linear cd-dbh relationship with the given values of the parameters. there is a positive relationship between tree crown diameter and dbh. the cd-dbh relationship of parkia biglobosa had r2adj =0.609. gering (1995) stated that “the ability to predict crown diameter from dbh provides an efficient method of obtaining an estimate of crown diameter”. similarly, bechtold (2003) reported high positive relationship for these variables for 87 tree species. foli et al. (2003) also reported r2=0.606 for entandrophragma angolense in ghana. the distribution of tree crown is germane to both forest and wildlife managers. tree crown diameter is one of the variables used for wildlife suitability index model (sousa, 1987; gering, 1995). also crown diameter is a veritable tool for monitoring forest health and a determinant of wildlife habitat value (kershaw et al., 2017). it forms the basis for determining tree crown structure and in consequence, crown social class. information on crown diameter is used together with other variables to derive other crown indices including crown thickness index, linear crown index, crown spread ratio, etc. (van laar and akҫa, 2007). 86 figure 3: observed and fitted weibull of the derived crown diameter distribution from dbh. figure 4: observed and fitted log-logistic of the derived crown diameter distribution from dbh. ogana and dau /journal of tropical forestry and environment vol. 9, no. 01 (2019) 80-88 87 4. conclusion this study has formulated a new crown distribution function based on the allometric relationship between tree crown diameter and diameter at breast height of parkia biglobosa. weibull and log-logistic distribution functions were used as the underlying distributions. the derived tree crown distribution was comparable to the actual crown distribution of the specie. thus, given the diameter distribution, the tree crown distribution of parkia biglobosa can be derived. this information can be used to assess the crown social class of the specie. the method of transformation could be extended to diameter to basal area, or diameter to volume etc., in so far there is a functional relationship between the variables. references adesoye, p.o. and ezenwenyi, j.u., 2014. crown diameter prediction models for tectona grandis linn. omo forest reserve. journal of forestry research and management, 11:72-87. bailey, r.l. and dell, t.r., 1973. quantifying diameter distributions with the weibull function. forest science, 19:97-104. bechtold, w., 2003. crown-diameter prediction models for 87 species of stand-grown trees in the eastern united states. southern journal of applied forestry, 27:269-278. cao, q.v., 2004. predicting parameters of a weibull function for modelling diameter distribution. forest science, 45:506-511. carretero, a.c. and alvarez, e.t., 2013. modelling diameter distributions of quercus suber l. stands in “los alcornocales” natural park (cadiz-malaga, spain) by using the two parameter weibull functions. forest systems 22:15-24. chukwu, o., chenge, i.b. and ezenwenyi, j.u., 2018. tree crown distribution for wildlife management of shasha forest reserve, nigeria. nigeria journal of wildlife management, 1:86-91. chukwu, o., dau, j.h. and ezenwenyi, j.u., 2017. crown-stump diameter model for parkia biglobosa benth species in makurdi, benue state, nigeria. journal of tropical forestry and environment, 7:43-53. deng, w.h., wei, g. and mei, z.g., 2003. nest and roost habitat characterisitcs of the grey-faced buzzard in northeastern china. journal of raptor research, 37:228-235. foli, e.g., alder, d., miller, h.g. and swaine, m.d., 2003. modelling growing space requirements form some tropical forest tree species. forest ecology and management, 173:79-88 gering, l.r., 1995. the relationship of diameter at breast height and crown diameter for species groups in hardin county, tennessee. southern journal of applied forestry, 19:177-184. gorgoso, j.j., gonzález, j.á., rojo, a. and grandas-arias, j.a., 2007. modelling diameter distributions of betula alba l. stands in northwest spain with the two-parameter weibull function. forest systems, 16:113-123. hemery, g.e., savill, p.s. and pryor, s.n., 2005. applications of the crown-stem diameter relationship for different species of broadleaved trees. forest ecology and management, 215:285-294 kershaw, j.a., ducey, m.j., beers, t.w. and hush, b.m., 2017. forest mensuration. 5th ed. chichester, uk; hoboken, nj; john wiley & sons, 632. mehtatalo, l., 2017. lmfor: functions for forest biometrics. r packages version 1.2. mehtätalo, l., 2013. forest biometrics with examples in r. university of eastern finland. school of computing, 406. mirzaei, m., aziz, j., mahdavi, a. and rad, a.m., 2016. modelling frequency distributions of tree diameter, height and crown area by six probability functions for open forests of quercus persica in iran. journal of forest research, 27:1-6. nord-larson, t. and cao, q.v., 2006. a diameter distribution model for even-aged beech in denmark. forest ecology and management, 231:218-225. 88 r core team, 2017. r: a language and environment for statistical computing. r foundation for statistical computing, vienna, austria. raptis, d., kazana, v., kazaklis, a. and stamatious, c., 2018. a crown width-diameter model for natural even-aged black pine forest management. forests, 9:610-629. sonmez, t., 2009. diameter at breast height-crown diameter prediction models for picea orientalis. african journal of agriculture research, 4:215-219. van laar, a., akҫa, a., 2007. forest mensuration. dordrecht, netherlands, springer, 389. west, p.w., 2015. tree and forest measurement, 3rd edition. springer cham heidelberg new york dordrecht london, 218. zarnoch, s.j., bechtold, w.a. and stoke, k.w., 2004. using crown condition variables as indicators of forest health. canadian journal of forest research, 34:1057-1070. zhang. l., packard, k.c. and liu, c.h., 2003. a comparison of estimation methods for fitting weibull and johnson’s sb distributions to mixed spruce-fir stands in northeastern north america. canadian journal of forest research, 33:1340-1347. bertin et al. /journal of tropical forestry and environment vol. 12, no. 02 (2022) 22-32 correspondance: biekopbertin@yahoo.fr issn 2235-9362 online ©2022 university of sri jayewardenepura. 22 physical and mechanical properties of ayous wood (triplochiton scleroxylon) from cameroon bertin. biekop1, 2, *, paul. william. mejouyo huisken1, 2, didier. fokwa1, 2, ebenezer njeugna1, 2 1 laboratory of mechanic, university of douala-cameroon 2 mechanic laboratory and adapted materials (lamma), enset – university of douala-cameroon *biekopbertin@yahoo.fr date received: september 14, 2022 date accepted: october 27, 2022 abstract the present study deals with ayous wood from the east cameroon forest reserve in the locality of abong-mbang. the water absorption rate of ayous wood and the absorption kinetics were evaluated. ayous wood reached its absorption saturation around 28 days. the primary diffusion coefficient was found to be 1.51 x 10-11 m2/s with a standard deviation of 0.23x10-11 m2/s while the saturation absorption rate is 144% with a standard deviation of 16.3%. about the modeling of kinetic absorption, many models were tested, and (sikame, 2014) was the best model for our experiments. in order to determine the mechanical properties, four point bending and compression test were done through the three orthotropic directions. it is found that the modulus of elasticity value is 8792.75 mpa with a standard deviation of 527 mpa and the fracture stress (σl) value is 53.6 mpa with a standard deviation of 8 mpa. longitudinal, radial and tangential compressive stress are 31.51 mpa, 29.15 mpa and 31.4 mpa respectively, with standard deviations of 4.34mpa, 4.52 mpa and 4.23 mpa. keywords: absorption kinetics, diffusion coefficient, orthotropic directions, modulus of elasticity, modulus of rupture. 1. introduction wood is a material derived from trees. its production constitutes a great wealth for central african economy (kisito, 2008). it is a biological composite, constituted of fibers as reinforcement, embedded in lignin as matrix. (pot, 2012). the fibers orientation leads to three orthotropic directions: radial, longitudinal and transversal. it is a natural material that has several advantageous characteristics such as its lightness, ease of absorbing and releasing water. the water absorption by wood assumes great importance, especially in the structure uses of wood (baronas, 2001), but a technological problem that limits its valuation resides in its mechanical variability. indeed, unlike other common building materials, wood is a living material whose properties are governed by nature. there may therefore be a variability of properties between trees of the same species. this is due to the presence of singularities such as knots, slots, and wire slope. it is therefore important to first determine the performance of each wood species before it is used in a construction application. the aim of the present work is to characterize ayous (tripochiton scleroxylon), a species intensively used in building construction as formwork for reinforced concrete, or structure elements. when this wood is used as formwork, it is influenced by climatic variations (rain and heat) due to its exposure on construction sites. it is therefore subjected to sorption phenomena mailto:biekopbertin@yahoo.fr mailto:biekopbertin@yahoo.fr bertin et al. /journal of tropical forestry and environment vol. 12, no. 02 (2022) 22-32 23 (saifouni, 2014). the knowledge of its absorption kinetics is fundamental for the understanding of its behavior under various conditions. 2. materials and methods 2.1 sampling the wood we have worked on, is ayous (tripochiton scleroxylon), a tropical wood of the eastern region of cameroon in the locality of abong-mbang. in order to obtain results that validate the methods used, a set of 1205 specimens were tested. three trees have been chosen in this species that have a diameter between 30 cm and 43 cm. they are straight and have few defects. this sampling allows a certain representativeness of the species studied. figure 1: tree trunks and sawing along longitudinal, radial and transverse directions figure 2: test specimens 2.2 hygroscopic behavior the absorption rate is determined by gravimetric method. this test was conducted by immersing sample in the water, removing it every two days and deducting the amount of water absorbed. if mi is the initial weight of the sample, and mt the actual value measured, then the equation 1 gives the absorption rate (scida, 2010). ta(t) = 𝑀𝑡−𝑀𝑖 𝑀𝑖 × 100 (1) where ta(t) is the absorption rate. bertin et al. /journal of tropical forestry and environment vol. 12, no. 02 (2022) 22-32 24 figure 3: hygroscopic measurement: (a) precision balance, (b) soaking tank if 𝑀∞ is the weight at saturation, the absorption ratio is calculated using equation 2. 𝑀𝑅(𝑡) = 𝑀𝑡 − 𝑀𝑖 𝑀∞ − 𝑀𝑖 × 100 (2) where 𝑀𝑅(𝑡) is the absorption ratio. from the mathematical point of view, the problem of water absorption by wood can be treated as a diffusion problem based on the fick’s second law of diffusion. the absorption kinetics of this wood species and the mathematical model of this absorption kinetics are then determined by testing several empirical models from the literature under matlab software. the fick diffusion coefficient gives a linear relationship between water flow through the porosity and the concentration gradient (crank, 1956). 𝐽𝑗 = −𝜌𝐷𝑖𝑗∇𝑐𝑗 (3) where jj is the diffusion flux, of which the dimension is the amount of substance per unit area time in kg.m-2s-1 and 𝜌 the mass per unit volume in kg m-3 dij is the binary diffusion coefficient or diffusivity in m-2s-1 ∇ is the symbol for the mathematical gradient. cj is the mass fraction. in this expression the diffusion coefficient dij is given by equation 4 𝐷𝑖𝑗 = 𝜋 ( 𝐾 4𝑀∞ ) 2 (4) where k is the slope of the linear part of the curve defined by equation 5 𝑤𝑡 = ( √𝑡 ℎ ) (5) 𝑤𝑡 is the water content at time t. bertin et al. /journal of tropical forestry and environment vol. 12, no. 02 (2022) 22-32 25 2.3 mechanical behavior bending test in order to determine the modulus of elasticity as well as the bending stress, four-point bending test is carried out according to the standard nf b 51-016 1987(seram, 1987), as shown in figure 4. the test is carried out using prismatic specimens of 360 mm length and 20 mm x 20 mm square cross-section, a compression press, a test stands and two pressure gauges. for this purpose, we made a support and loading device that was adapted to the existing press. figure 4: four points bending test figure 4: bending moment the modulus of elasticity and the bending tensile stress are derived by equation 6. moe = 𝑝𝑙3 48𝐼𝛥𝑚𝑎𝑥 [ 3(𝑙−𝑎) 2𝑙 − (𝑙−𝑎)3 𝑙3 ] (6) moe : modulus of elasticity i: quadratic moment of the section of the sample δ: maximal deflexion obtained from the test. p maximal load a: dimension of the section of the sample (a= 20 mm) l: the distance between supports (320 mm) the maximum bending moment is given by equation 7 𝑀𝑚𝑎𝑥 = 𝑝 2 𝑎 (7) 𝑀𝑚𝑎𝑥: the maximum bending moment. 320 80 40p 240 150 350 x mm 100 30050 250 m(x) n.mm 0 200 bertin et al. /journal of tropical forestry and environment vol. 12, no. 02 (2022) 22-32 26 equation 8 gives the maximal static bending stress. 𝜎𝑚𝑎𝑥 = 3𝑝𝑎 𝑏3 (8) 𝜎𝑚𝑎𝑥 : the maximal static bending stress compression test the compression test is conducted by standard nfb 51-007 (seram, 1987). the test method is based on the following principle: the chosen test (compression) aims to impose a uniform uni-axial stress state on a prismatic specimen and, by measuring the resulting deformations, to evaluate the elastic compliances expressed in the reference frame linked to the specimen. the samples are taken through the three orthotropic directions according to the figure 5. figure 5: the three orthotropic directions of wood the practice is to use three specimens as shown in figure 6 below. (a) (b) figure 6: the three specimens in the three directions (a), test machine and specimen loading mode in compression (b) for each test, if p is the maximum force applied to the specimen, the stress is given by equation 9 𝜎 = 𝑃 𝑏2 (9) bertin et al. /journal of tropical forestry and environment vol. 12, no. 02 (2022) 22-32 27 where 𝑏2 is the section of the sample. (20x20mm2). the modulus of elasticity is then given by. moe = 𝑃𝐿 𝑏2∆𝐿 (10) where p is the maximum force applied to the specimen, and 𝐿 the length of the sample where ∆𝐿 is the variation of the length of the sample under the maximum force p. 3. results and discussion 3.1 hygroscopic behavior the water absorption kinetics was studied. the graph of the absorption kinetics curve is shown in figure 7. this figure shows the variation of water absorption ratio with time. it appears that the saturation happens in twenty-eight days. the rate of absorption is 144% with a standard deviation of 16.3%. \ figure 7: absorption kinetics of ayous wood the modelling of the absorption kinetics was done in matlab using mode ls from the literature. figure 8 presents this modelling. 0 0.2 0.4 0.6 0.8 1 1.2 0 4 8 12 16 20 24 28 32 w a te r a b so rp ti o n r a ti o time (day) s1 s2 s3 s4 s5 s6 s7 s8 s9 s10 time (day) w a te r a b so rp ti o n r a ti o bertin et al. /journal of tropical forestry and environment vol. 12, no. 02 (2022) 22-32 28 figure 8: experimental curve of ayous wood and curves of models to evaluate the goodness of fit of each model, two criteria were used. coefficient of determination (r-square) and root mean square error (rmse), as given in the table 1. table 1: distribution of the average parameter model of the absorption kinetics of ayous wood model names goodness of fit r-square adjusted r-square rmse (sikame ,2014) g(x)= c-a.exp(-k.x)-b.exp(-m.x) 0.9979 0.9962 0.01959 (pilosof, 1987) g(x)=a+ 𝒃.𝒙 𝒄+𝒙 0.9853 0.9811 0.04378 experimental 0.9980 0.9974 0.01622 (czel ,2008) g(x)=a. 𝒙𝒎 0.9339 0.9258 0.08672 g is the model equation the root mean square error (rmse) is given by equation 11 𝑅𝑀𝑆𝐸 = √ ∑ (𝑚𝑐𝑖−𝑚𝑒𝑖) 2𝑛 1 𝑛 2 (11) w a te r a b so rp ti o n r a ti o 0 .2 0 .4 0 .6 0 .8 1 1 .2 1 .4 0 5 10 15 20 25 30 times (days) experimental curve and curves of models bertin et al. /journal of tropical forestry and environment vol. 12, no. 02 (2022) 22-32 29 where 𝑚𝑐𝑖 is the theoretical mass, 𝑚𝑒𝑖 is the predicted mass, n the number of observations the mathematical model that best describes the absorption kinetics of ayous wood is the sikame model (2014) given by equation 12 below. g(x) = c − a . exp(−k. x) − b. exp(−m. x) (12) where a b and c are constants and k and m are the scattering parameters. table 2: coefficients of sikame model. coefficients (with 95% confidence bounds) values a 0.001366 b 0.002965 c 1.04 k 0.1756 m 0.203 the corrected primary scattering coefficient deduced from this absorption kinetics is 1.51.10-11 m²/s. this value is in the order of magnitude of the diffusion coefficients of woods of the same characteristic in the literature. it is experimentally proven that the diffusion coefficient of medium-heavy tropical woods varies from 10-13 m²/s to 10-11 m²/s while that of heavy woods varies from 10-14 m²/s to 10-12 m²/s with a relative error of 10%. the diffusion coefficient of tropical woods is lower than the diffusion coefficients of temperate woods and also differs according to the density (khazaei, 2008). the heavier the wood, the lower its diffusion coefficient, i.e. the more difficult it is to lose water (nsouandele, 2009). 3.2 mechanical properties of wood in 4-point bending its maximum deflexion value δ is 10.73 mm with a standard deviation of 0.69 mm. the 4point bending test produced the curve given by figure 9. from this curve we determine the value of the longitudinal modulus of elasticity moe= 8792.75 mpa. it should be noted that this value of modulus of elasticity is within the range of moduli of elasticity of this species given in the literature 7260 mpa with a standard deviation of 1574 mpa (gérard, 1998). figure 9: four point bending test, evaluation of modulus of elasticity y = 3188.1x 0.9754 r² = 0.9993 0 10 20 30 40 50 0 0.002 0.004 0.006 0.008 0.01 0.012 0.014 0.016 s tr e ss ( m p a ) strain (∆𝐿/𝐿) bertin et al. /journal of tropical forestry and environment vol. 12, no. 02 (2022) 22-32 30 (a) (b) figure 10: comparison of modulus of elasticity of ayous wood with other species (a) longitudinal breaking stress of some species (b) a static bending modulus or modulus of elasticity of 8792.75 mpa with a standard deviation of 527 mpa is obtained for this species, as well as a comparison with other similar woods (softwoods) in the literature. in this test, the bending stress parallel to the grain was determined to be 74.11 mpa. this value is high compared to other similar woods in the literature, namely ilomba and dibetou with similar densities (gérard, 1998). table 3: fracture stress and modulus of elasticity for the four point bending test. four point bending test fracture stress in mpa (sd) modulus of elasticity in mpa (sd) 53.6 (8) 8792.75(527) ayous ilomba dibetou breaking stress(mpa) 74.11 70 80 0 10 20 30 40 50 60 70 80 90 b r e a k in g s t r e ss wood species ayous ilomba dibetou young modulus (mpa) 8792.75 8200 8400 7000 7500 8000 8500 9000 9500 y o u n g m o d u lu s wood species bertin et al. /journal of tropical forestry and environment vol. 12, no. 02 (2022) 22-32 31 3.2 uni-axial compression test this uniaxial compression test allowed us to draw the curves below. figure 11: uni-axial compression test: radial compression, tangential compression, longitudinal compression. the values for modulus of elasticity and stress at break from this test are given in the table 4. table 4: stress at break and modulus of elasticity in compression compressive stress in mpa (sd) modulus of elasticity in mpa (sd) longitudinal compression 31.51 (4.34) 6529 (510) radial compression 29.15 (4.52) 4041 (309) tangential compression 31.49 (4.23) 4029 (301) based on these results, we observed that the modulus of elasticity in longitudinal compression is greater than the moduli of elasticity in radial and tangential compression. this value of longitudinal modulus is also within the range of moduli of elasticity of this species given in the literature 7260 mpa with a standard deviation of 1574 mpa (gérard, 1998). this reflects the use of this species in structures in the longitudinal direction (parallel to the grain). 4. conclusion the main objectives were to characterize the kinetics of ayous wood and its mechanical behavior. water diffusion in this species has shown that its water absorption rate is high in the first eight days of the test, and gradually decreases to stabilize at saturation absorption around 28 days. this absorption rate is 144% with a standard deviation of 0.163%. the process that led to the determination of this value consisted of successive weighing carried out on average every 02(two) days until saturation (mass stabilization). when we use matlab software the model of sikame is the one that best fits the absorption kinetics of this species. the correlation coefficient is r2= 0.9979 and the rmse value equal to 0.01959. this model value is close to the experimental value which is 0.01622. the average primary diffusion coefficient is 1.15.1011m²/s. the four point bending test revealed a tensile stress of 53.6 mpa and a modulus of elasticity of 8792.75 mpa.the uni-axial test revealed a longitudinal compressive strength of 0 5 10 15 20 25 30 35 40 0 0 . 0 0 2 0 . 0 0 4 0 . 0 0 6 0 . 0 0 8 0 . 0 1 0 . 0 1 2 s t r e s s ( m p a ) st(∆𝐿/𝐿) radial compression tangential compression longitudinal compression bertin et al. /journal of tropical forestry and environment vol. 12, no. 02 (2022) 22-32 32 31.51 mpa, a tangential compressive strength of 31.49 mpa, and a radial compressive strength of 29.15 mpa. the moduli of deformation in the different directions in compression are: el = 6529 mpa, er = 4041 mpa et = 4029 mpa. in future work, it will be necessary to study a creep ratio behavior of this species (viscoelastic and mechano-sorptive behavior). references baronas, r., f.ivanauskas, i,juodeikienes, a. kajalavicius, 2001. modelling of moisture movement in wood during outdoor storage. non linear analysis : modelling and control, 6(2) : 3-14. crank j, 1956. the mathematics of diffusion, oxford university press, new york. czel g., czigany, t., 2008. a study of water absorption and mechanical properties of glass fiber/polyester composite pipeeffects of specimen geometry and preparation, journal of composite materials, vol.42, no.26 pp.2855-2827. scida, d., assarar, a., rezak ayad, christophe poilane, 2011. effect of moisture on the mechanical behavior of flax fibre composites (jnc17). scida,d., assarar, a., ayad,r., poilane, c., 2011. effect of humidity on mechanical properties of flax fibres reinforced composites. gerard, j., kouassi, a.e., daigremont, c., detienne, d.fouquet, m.vernay, 1998. synthèse sur les caractéristiques technologiques de référence des principaux bois commerciaux africains. ciradforet, campus international baillarguet bp 5035 34032 montpellier cedex 01 france guillaume pot, 2012. mechanical characterization of green wood during its maturation and modeling of the gravitropic reaction of young poplars. doctoral thesis, university. blaise pascal; clermont ii. khazaei j, 2008.water absorption characteristics of three wood varieties, cercetari agronomice in moldova, vol. xli, n°. 2(134). mvogo j k, 2008. mechanical grouping by vibratory method, phd thesis university of yaoundé 1, university of bordeaux 1. nsouandele j, b. bonama, m simo tagne, d. njomo, 2009. determination of the diffusion coefficient of water in the tropical wood, laboratoire physique appliquée, ecole normale supérieure de yaoundé. omar saifouni, 2014. modelling rheological effects in materials: application to the mechanosorptive behavior of wood. thesis obtained at the university blaise pascal clermont ii. pilosof, r.boquet, g.b batholomai, 1987. kinetics of water uptake to food powders, journal of food science, vol, 50, no1,pp. 1538-1541. seram, 1987. essai mécanique du bois, ecole nationale supérieure d’arts et métiers, centre d’aixen-provence c.i.c.b.l 13241 marseille cedex 1. sikame tagne, e. njeunia, m. fogue, j-y drean, a. nzeukou, d. fokwa, 2014. study of water absorption in vinefera fibres from bandjoun cameroun, the scientific word journal, article id 912380 11 pages. simo m tagne, 2014. numerical study and mass transfer during the thermal drying of tropical woods, int. j. of thermal & environmental engineering, vol. 8, n°2 9-15. simo m tagne, b. beguide, d. njomo, 2010. modélisation et simulation numérique du séchage des bois d’ayous et d’ebène. validation expérimentale, laboratoire de physique appliquée, ecole normale supérieur université de yaoundé i, janvier 2010, revue des énergies renouvelables, vol. 13 n°1 13-24. microsoft word idrood and manage[1] idroos & manage /journal of tropical forestry and environment vol. 2, no. 02 (2012) 13-26 13 aquatic life health quality assessment of the bolgoda canal and waga stream with respect to selected physico-chemical parameters and bioindicators f.s. idroos 1 and p.m. manage* 1 1 department of zoology, university of sri jayewardenepura, nugegoda, sri lanka date received: 29-05-2012 date accepted: 21-08-2012 abstract the relationship between some physico-chemical parameters and bioindicators in bolgoda canal and waga stream in colombo, sri lanka was assessed from february to july 2010. the objective of the study was to evaluate the quality of aquatic health in the two water bodies using some physico-chemical parameters and bioindicators. physico-chemical parameters of the water bodies were measured. macro invertebrates and phytoplankton were studied as biological indicators. quantification of macro invertebrates were carried out and pollution tolerant index (pti) of bolgoda canal and waga stream was calculated according to the standard manual published by the united states environmental protection agency (usepa). macro invertebrate component in the bolgoda canal represented both moderately pollution tolerant (nepa cinerea, zygopteran nymphs) and pollution tolerant (planorbella trivolvis, promacea bridgesi, gerris sp, lethocerus americanus, plea frontalis, cerithiidae sp, tubifex tubifex) organisms while in waga stream only pollution sensitive organisms (paludomous loricatus, paludomous zeylanicus, cylindrostesthus productus, plecopteran nymphs, psephenidae larvae, aegla sp, ephemeropteran nymphs) were reported. the pti value of bolgoda canal ranged from 17.00 to 19.90 where as in waga stream was ranged from 34.00 to 39.60 indicating poor and good water quality respectively. the phytoplankton composition of both water bodies were analyzed using shannon wiener diversity index (swdi). swdi for phytoplankton in bolgoda canal was ranged between 0.674±0.36 and 1.513±1.80 and in waga stream was ranged from 1.89±0.72 3.01±1.89 indicating low and high diversity respectively. data analysis by principle component analysis (pca) showed that physico-chemical parameters, pti and swdi of the sampling locations in bolgoda canal and waga stream were clustered into three distinct groups according to the site selection. regression analysis showed temperature, ph, do, nitrate concentration and bod had a significant effect on the pti value of the bolgoda canal and waga stream. key words: physico-chemical parameters, bioindicators, pollution tolerant index (pti), shannon wienner diversity index (swdi), principal component analysis (pca). 1. introduction biological monitoring or biomonitoring, is the use of biological response to assess changes in the environment, generally changes due to anthropogenic causes (ramakrishna, 2003) and is a valuable assessment tool that is receiving increased use in water quality monitoring programs (kennish, 1992). biomonitoring involves the use of indicators, indicator species or indicator communities such as benthic *correspondence: path@sjp.ac.lk tel: +94 11 2804515 issn 2235-9370 print / issn 2235-9362 online ©2012 university of sri jayewardenepura idroos & manage /journal of tropical forestry and environment vol. 2, no. 02 (2012) 13-26 14 macroinvertebrates, fish, algae and bacteria (ramakrishna, 2003). certain aquatic plants have also been used as indicator species to monitor pollution status and nutrient enrichment of a water body (batiuk et al., 1992). it has been documented that monitoring of water quality using benthic macroinvertebrates and physicochemical parameters to determine the biological richness of a stream is a successful method to assess the health of a water body (duran, 2002). fresh water flora and fauna play an important role as indicators of aquatic pollution as biological communities provide a more faithful reflection of environmental conditions, since they are continuously exposed and sensitive to changes in environment (rosenberg and resh, 1993; tudorancea et al., 1979). pollution tolerant index (pti) is currently used by the united states environmental protection agency (usepa) in order to determine the quality of water based on macro invertebrates. the pti index categorizes macroinvertebrates into pollution sensitive, moderately pollution sensitive and pollution tolerant groups and are assigned with a numerical value depending on their pollution tolerance levels. thus, there are three health status of water depending on pti values (pti value greater than 40, the water quality is considered as good, within 20-40 water quality is fair and the value less than 20 is considered as poor quality). coliform bacteria have been used to evaluate the general quality of water. moreover, fecal coliforms, escherichia coli, salmonella spp, zooplankton and zoobenthos are used as water quality bioindicators as they respond quickly to environmental change and may be effective indicators of alterations in water quality (gannon and stemberger, 1978). an abundance of phytoplankton is indicative of nutrient pollution (de lange, 1994). palmer (1959) has demonstrated that algal assemblages could be used as indicators of both clean and polluted waters and shannon wiener diversity index (swdi) can be used to assess the quality of the water depending on the diversity of phytoplankton community. gray (1994) has documented that changes in diversity index or any other parameters of community structure can be used to assess degree of environmental stress assuming that the change in index value is related to the intensity of pollution. analysis of physiochemical parameters of a water body gives information on the present status of health of the water body (buss et al., 2003; gonçalves and menzes, 2011). thus, the present study was carried out in bolgoda canal and waga stream with an aim to assess the health status of aquatic life in both water bodies with respect to some selected physico-chemical parameters and bioindicator species. 2. materials and methods 2.1. study areas this study focuses on two types of water ways: polluted and relatively unpolluted water body in the colombo district. bolgoda canal (6° 50' 0"n, 79° 53' 0" e), attidiya which is flowing in amidst of bellanwila-attidiya marsh is situated on the south-eastern outskirts of colombo (figure 1). the depth of the canal is approximately 8 feet and the flow rate is 0.0270m/s. most industrial effluents, including toxic dyes and other industrial waste from approximately 20 factories in rathmalana are discharged through this canal (cea, 1993). bolgoda canal was chosen for the study as this area is under human pressure that includes encroachment, domestic sewage, waste water discharges, storm water runoffs and dumping of industrial waste effluents. on the other hand waga stream (6° 54' 22"n, 80° 8' 7" e), maththaka (figure 2) is flowing across an unurbanized area in colombo district receiving comparatively less levels of contaminants (manage unpublished data, waga stream). nevertheless, domestic discharges from nearby human settlements, effluents from rubber factory, rubber estate and tea estates are added to the stream as point and non-point source pollutants. three locations (1, 2 and 3) were chosen in both the bolgoda canal and waga stream (figure 1 and figure 2) representing areas under human activities and relatively undisturbed areas. in the bolgoda canal, idroos & manage /journal of tropical forestry and environment vol. 2, no. 02 (2012) 13-26 15 location 1 received discharges from household, location 2 was a feeding and bathing place for cattle and where location 3 was situated in an undisturbed area. in the waga steam (figure 2) location 1 received effluent from rubber factory, location 2 received domestic loadings and location 3 was an undisturbed area. figure 1: sampling locations of bolgoda canal system (source: wetland site report and conservation management plan, bellanwil attidiya marsh, 1993) figure 2: sampling locations of waga stream 2.2. sample collection and chemical analysis monthly sampling was carried out for a period of six months from february to july 2010. samples were collected within two days in both sites during 8.30 am to 12.00 pm. surface water samples were collected using a 10l plastic bucket and temperature ( o c), dissolved oxygen (mg/l), ph and electric idroos & manage /journal of tropical forestry and environment vol. 2, no. 02 (2012) 13-26 16 conductivity (µs/cm) were measured at the site itself using thermometer (immersion, philip harris, england), do meter (oxi 320/ set, wtw co., weilheim, germany), ph meter (330/ set ,wtw co., weilheim, germany) and conductivity meter (340a/set ,wtw co., weilheim, germany) respectively. samples were kept in an ice box during transportation and stored in 4 o c until analysis. nitrate concentration (mg/l) and orthophosphate concentration (mg/l) were measured according to standard spectrophotometric method (silva et al. 1996). five days biochemical oxygen demand (bod5), alkalinity, sulphide concentration and hardness were measured within 24 hours according to standard titrometric methods. 2.3. biological studies the benthic macro invertebrate community in both water and mud was sampled in 1m 2 areas by the kicking method for 15 minutes in order to include all possible microhabitats at each station. in certain locations with the presence of large stones they were first picked out and washed into the kick net to remove larvae and other attached macroinvertebrates. in addition, macroinvertebrate samples were separated from the macrophytes and the sediment using sieves (250 µm). collected specimens were washed with same water and sorted based on morphological features and identified to the lowest possible taxon (species, genus or family). identification was done within 4 hours of sample collection, using the standard manual of volunteer stream monitoring of united states environmental protection agency (1996) and the guide for freshwater fauna of ceylon (mendis and fernando, 2002). unknown specimen samples were rinsed with distilled water and fixed with 5% formalin at the site and transferred to the laboratory for further identification. further, identification of unknown species was carried out at the national museum, referring the available specimens and following the identification keys (mendis and fernando, 2002). 2.4. calculation of pollution tolerant index (pti) pollution tolerant index (pti) for the canal was calculated according to standard manual volunteer stream monitoring of usepa. 2.5. analysis of phytoplankton composition phytoplankton samples were collected by filtering 100 liters of water through 55µm plankton net and were fixed with acidified lugals’ solution at final concentration of 1% followed by natural sedimentation. identification of plankton was carried out under light microscopy using standard keys (prescott, 1970; manage, 2012). enumeration of phytoplankton was done using a shedwick rafter counting chamber under the light microscope (x 40). 2.6. calculation of shannon wiener diversity index (swdi) swdi of phytoplankton composition in the canal was calculated according to following formula. h’ = ∑ pi ln pi i =1 where, h’: species diversity index, s: number of species, pi: proportion of individuals of each species belonging to the “i” th species of the total number of individual 2.7. statistical analysis principal component analysis (pca) was applied using primer 5 software for physico-chemical parameters, pti and swdi values of bolgoda canal and waga stream. the effect of physico-chemical parameters on pti and swdi were analyzed separately by regression analysis and any significant differences were determined at a 0.05 probability level using minitab 13.2 statistical software. idroos & manage /journal of tropical forestry and environment vol. 2, no. 02 (2012) 13-26 17 3. results total number of nine macroinvertebrate species belonging to three different classes were recorded (table 1) in bolgoda canal and they were grouped as; gastropoda (3 species), insecta (5 species) and clitellata (1 species). the results showed that the bolgoda canal possessed pollution tolerant and moderately pollution tolerant species with a range of mean pti between 18.06 ± 0.93 and 19.46 ± 0.51 (table 2) indicating poor quality water according to the usepa. in contrast, total of 7 macroinvertebrate species were recorded from waga stream; gastropoda (2 species), insecta (4 species) and crustcea (1 species). the results revealed that, the waga stream was characterized as having pollution sensitive species with a range of mean pti between 35.43±1.24 – 39.10±0.70 (table 4) which indicates good quality water. among gastropods, paludomus loricatus and paludomus zeylanicus were recorded as local aquatic snails belonging to sri lanka from waga stream and they were the dominant macroinvertebrates inhabiting throughout the stream bottom. table 1: numerical occurrence of macroinvertebrates in the bolgoda canal nr not recorded table 2: pollution tolerant index (pti) for indicator species in bolgoda canal class species february march april may june july gastropoda planorbella trivolvis 3.00±0.50 2.00±1.00 2.0±0.00 3.00±1.00 4.00±2.00 2.00±1.73 promacea bridgesi 4.00±1.00 5.00±2.64 3.00±1.00 4.00±1.00 3.00±2.64 5.00±2.64 cerithiidae sp 12.0±3.00 10.0±1.60 5.00±1.73 9.00±1.00 13.0±3.60 9.00±1.00 insecta gerris sp 3.00±1.00 4.00±1.73 2.00±1.00 3.00±0.00 3.00±1.00 2.00±0.00 lethocerus americanus 4.00±2.00 4.00±1.00 3.00±1.00 2.00±1.00 1.50±0.70 4.00±2.64 plea frontalis 21.0±2.60 20.0±2.64 13.0±2.19 14.0±2.64 22.0±2.07 11.0±1.24 zygopteran nymphs 4.50±3.50 6.00±2.82 4.00±2.64 2.00±1.00 3.00±1.73 nr nepa cinerea 2.0±0.00 nr nr 3.00±0.00 2.00±1.73 1.00±0.00 clitellata tubifex tubifex 1.50±2.00 nr 2.00±1.00 nr 1.50±0.70 nr month pti values locations mean ± sd 1 2 3 february 19.00 18.60 19.80 19.13±0.61 march 18.50 18.70 17.00 18.06±0.93 april 18.90 19.90 19.80 19.5±0.52 may 19.60 18.90 19.90 19.46±0.51 june 18.50 18.90 18.60 18.66±0.21 july 18.50 17.90 18.80 18.40±0.46 idroos & manage /journal of tropical forestry and environment vol. 2, no. 02 (2012) 13-26 18 table 3: numerical occurrence of macroinvertebrates in waga stream nr not recorded table 4: pollution tolerant index (pti) calculated to indicator species in waga stream month pti values locations mean ± sd 1 2 3 february 38.40 38.90 36.90 38.06±1.04 march 36.20 36.10 34.00 35.43±1.24 april 36.90 38.40 37.90 37.73±0.76 may 38.40 38.20 38.20 38.26±0.11 june 38.40 37.90 39.50 38.60±0.81 july 38.30 39.40 39.60 39.10±0.70 phytoplankton species in bolgoda canal and waga stream and their percentage value together with shannon index values are given in table 5 and table 6. phytoplankton composition of bolgoda canal contained pollution tolerant algae species (table 5) and the shannon diversity index ranged between 0.674±0.36 to 1.513±1.80 during the sampling period. in waga stream mostly clean water algae species were recorded (table 6) and shannon diversity index ranged between 1.89±0.72 to 3.06±0.82. table 5: species composition and shannon index value of phytoplankton in bologoda canal sp 1.-spirulina sp., sp 2.-phacus caudatus, sp 3.-scenedesmus armatus, sp 4.-pediastrum duplex, sp 5-. microcystis aeraginosa, sp 6-.actinastarum sp. class species february march april may june july gastropoda paludomus loricatus 15±5.00 10±5.00 11.33±5.50 9±1.73 12±4.00 14±4.00 paludomus zeylanicus 2.3±1.50 6±2.64 7±1.00 3±1.73 4±2.64 5±1.00 insecta cylindrostethus produtus 8±1.00 8±2.00 6.33±3.78 4±1.00 7±2.00 6±1.00 plecopteran nymphs 1.5±0.70 nr 6±1.37 nr 3±0.67 3±1.31 psephenidae larvae 8±2.00 9±1.00 7.66±1.50 5±2.64 2±1.00 3±1.00 ephemeropteran nymphs 1±0.02 3±1.40 2±1.21 1±0.76 1.56±0.71 nr crustacea aegla sp nr 3±0.52 2±1.40 nr 1±0.03 nr month total number of phytoplanktons (cells/ml) percentage composition of species shannon wienner index value sp1 sp 2 sp 3 sp 4 sp 5 sp 6 february 2033±0.19 45.70 13.40 7.80 5.90 21.10 6.10 0.674±0.36 march 1567±0.24 34.98 6.78 3.96 20.07 28.78 5.43 1.335±0.29 april 1702±0.51 40.07 3.90 2.77 19.71 25.63 7.92 1.265±0.11 may 1938±1.37 42.08 5.32 2.02 24.22 23.05 3.31 1.232±1.28 june 1688±1.17 36.03 6.71 3.09 12.46 29.02 12.51 1.310±0.91 july 1309±0.29 25.09 10.31 5.24 13.43 28.61 17.32 1.513±1.80 idroos & manage /journal of tropical forestry and environment vol. 2, no. 02 (2012) 13-26 19 table 6: species composition and shannon index value of phytoplankton in waga stream month total number of phytoplanktons (cells/ml) percentage composition of species shannon wienner index value sp1 sp 2 sp 3 sp 4 sp 5 february 1024±1.31 21.10 7.44 34.35 22.77 14.43 3.01±1.89 march 1567±0.87 26.09 5.64 41.21 12.21 14.85 2.88±1.20 april 1011±0.51 22.36 17.90 32.39 15.24 12.11 3.06±0.82 may 1450±1.67 33.47 3.67 45.67 10.76 6.43 2.90±1.34 june 1788±1.82 44.43 2.01 36.04 12.00 5.52 1.89±0.72 july 1609±0.81 28.01 12.76 31.72 13.30 14.21 2.76±0.19 sp 1.-microcystis wesenbergii., sp 2-. ulothrix sp, sp 3-entzia acuta. sp 4-elaktothrix genevensis, sp 5-.staurastrum sp. the mean water temperature of bolgoda canal was of 29.05 ±0.22 o c (table 7) and the mean ph was 5.67±0.23. the ec and do values of the bolgoda canal was recorded as 406.85±100.40 µs/cm and 3.54±0.66 mg/l respectively. total nitrate concentration ranged between 1.22 to 1.46 mg/l, while orthophosphate concentration between 4.56 to 5.45 mg/l during the study period. the mean bod level of the bolgoda canal was of 3.62±0.3 mg/l. the mean alkalinity, sulphide and hardness concentrations were recorded as 1.69±0.19 m mol/l, 1.23 x 10 -4 ±0.27 mol/l, and 2.06±0.66 m mol/l respectively. in waga stream mean temperature was 25.20±1.00 o c and mean ph and ec were 6.14±0.12 and 31.75±3.45µs/cm respectively. the mean do value was 6.99±0.75mg/l. mean total nitrate and orthophosphate concentrations in the waga stream were 0.63±0.25 mg/l and 6.18±0.78mg/l respectively. mean alkalinity value and bod were 0.47±0.12 m mol/l and 0.042±0.01mg/l respectively. sulphide and hardness were not recorded. table 7: mean physico-chemical parameters in the bologoda canal and waga stream during the study period nr–not recorded the principal component analysis (pca) produced two principal components that collectively explained 100.0% of the variance of physico-chemical parameters, pollution tolerant index and shannon diversity index in bolgoda canal and waga stream (table 8 and 9). pca ordination of the reaches according to the 12 variables describing physico-chemical parameters, pollution tolerant index and shannon diversity index provided a strong discrimination of the three sites in bolgoda canal and waga stream (figures 3 and 4). physico-chemical parameter water body bolgoda canal waga stream range mean range mean temperature ( o c ) 28.30-29.80 29.05 ±0.22 24.20-26.20 25.20±1.00 ph 5.45-5.90 5.67±0.23 6.02-6.25 6.14±0.12 electric conductivity (µs/cm) 306.40-507.30 406.85±100.40 28.30-35.20 31.75±3.45 do (mg/l) 2.88-4.20 3.54±0.66 6.807.30 6.99±0.75 total nitrate (mg/l) 1.22-1.46 1.35±0.09 0.32-0.97 0.63±0.25 orthosphate (mg/l) 4.56-5.45 5.14±0.5 5.30-6.80 6.18±0.78 bod (mg/l) 3.26-3.89 3.62±0.3 0.032-0.054 0.042±0.01 alkalinity (m mol/l) 1.51-1.90 1.69±0.19 0.35-0.60 0.47±0.12 sulphide (10 -4 mol/l) 0.92-1.42 1.23±0.27 nr nr hardness( m mol/l) 1.30-2.50 2.06±0.66 nr nr idroos & manage /journal of tropical forestry and environment vol. 2, no. 02 (2012) 13-26 20 table 8: axis eigenvalues and weighted correlations between physico-chemical parameters, pti and swdi variables of pca of bolgoda canal samples variables that explain a significant amount of variation amongst samples following forward selection (*p< 0.05). variable pc1 pc2 eigen value 6.71 5.29 % of var. 55.9 44.1 cumulative value 55.9 100.0 pti -0.140 0.405 swdi -0.374 0.105 temperature ( o c ) 0.307 -0.264 ph 0.386 0.002 electric conductivity(µs/ cm ) -0.219 -0.358 do(mg/l) -0.245 -0.336 total nitrate (mg/l) -0.368 0.132 orthophosphate (mg/l) 0.201 -0.371 bod (mg/l) -0.372 -0.115 alkalinity (m mol/l) -0.038 -0.433 sulphide (x10 -4 mol/l) 0.160 0.396 hardness( m mol/l) -0.384 -0.042 table 9: axis eigenvalues and weighted correlations between physico-chemical parameters, pti and swdi variables of pca of waga stream samples variables that explain a significant amount of variation amongst samples following forward selection (*p< 0.05). the pca plot of bolgoda canal (figure 3) confirmed that site 1 is characterized by high temperatures and ph, moderate orthophosphate concentrations, ec and alkalinity values. site 2 was characterized by high, nitrate concentrations, orthophosphate concentrations, ec, bod, alkalinity and high swdi values. further, these characteristics were shared by site 3 with high nitrate, bod and high swdi values but comparatively high pti values than the other two sites. variable pc1 pc2 eigen value 8.49 1.51 % of var. 84.9 15.1 cum % 84.9 100.0 pti -0.294 0.419 swdi -0.327 -0.246 temperature ( o c ) -0.260 -0.530 ph 0.253 0.550 electric conductivity (µs/cm) 0.332 -0.206 do(mg/l) -0.343 0.044 total nitrate (mg/l) 0.343 0.028 orthophosphate (mg/l) 0.343 0.015 bod (mg/l) 0.318 -0.306 alkalinity (m mol/l) 0.332 -0.207 idroos & manage /journal of tropical forestry and environment vol. 2, no. 02 (2012) 13-26 21 figure 3: ordination of the three study sites based on pc1 and pc2 scores of principal component analysis between physico-chemical parameters, pti and swdi among the three sites of bolgoda canal figure 4: ordination of the three study sites based on pc1 and pc2 scores of principal component analysis between physico-chemical parameters, pti and swdi among the three sites of waga stream. high alkalinity, high phosphate, high conductivity high total nitrate, high bod, high shannon diversity index high temperature, high ph -2.0 -1.5 -1.0 -0.5 0 0.5 1.0 1.5 2.0 2.5 3.0 pc1 -2.5 -2.0 -1.5 -1.0 -0.5 0 0.5 1.0 1.5 2.0 2.5 p c 2 loc1 loc2 loc3 high pti high bod, high temperature high do, high pti, high swdi high total nitrate, high phosphate, high conductivity, high alkalinity -4 -3 -2 -1 0 2 1 pc1 -1.5 -1.0 -0.5 0 0.5 1.0 1.5 p c 2 loc1 loc2 loc3 high ph 3 idroos & manage /journal of tropical forestry and environment vol. 2, no. 02 (2012) 13-26 22 the pca plot for waga stream (figure 4) indicated high bod, temperature, nitrate, orthophosphate, ec and alkalinity in site 1. site 2 shared some of the similar values from site 1 like high nitrate, orthophosphate, ec and alkalinity but with comparatively high ph value. site 3 was characterized by high bod, temperature, do, pti and high swdi values. high cumulative percentage as high as 100.0% of the total variation of the physico-chemical parameters pti and swdi could be explained by both pc1 and pc2 axis. the regression analysis was made between physico-chemical parameters and pti values of bolgoda canal and waga stream are presented in table 10. the results convinced temperature, ph, do, nitrate and bod had a significant effect on the pti value of the bolgoda canal and waga stream. regression analysis between physico-chemical parameters and swdi of thebolgoda canal and waga stream (table 11) showed temperature, ph, do, nitrate concentration and bod values had a significant effect on swdi values of bolgoda canal at p<0.05 significance level and temperature, ph, do, nitrate and orthophosphate had a significant effect at p<0.05 significance level on the swdi of waga stream. table 10: regression values between the physico-chemical parameters and pti of bolgoda canal and waga stream at significance level p < 0.05 nr – not recorded table.11. regression values between the physico-chemical parameters and swdi of bolgodacanl and waga stream at significance level p < 0.05 nr – not recorded parameter bolgoda canal waga stream (p value) (p value) temperature ( o c ) 0.038 0.046 ph 0.003 0.01 electric conductivity (µs/ cm ) 0.214 0.108 do (mg/l) 0.003 0.001 total nitrate (mg/l) 0.001 0.003 orthophosphate (mg/l) 0.362 0.582 bod (mg/l) 0.04 0.006 alkalinity (m mol/l) 0.456 0.882 sulphide (x 10 -4 mol/l) 0.679 nr hardness ( m mol/l) 0.061 nr parameter bolgoda canal waga stream (p value) (p value) temperature ( o c ) 0.022 0.026 ph 0.028 0.042 electric conductivity (µs/ cm ) 0.401 0.361 do (mg/l) 0.0330 0.031 total nitrate (mg/l) 0.0429 0.004 orthophosphate (mg/l) 0.914 0.001 bod (mg/l) 0.021 0.518 alkalinity (m mol/l) 0.128 0.109 sulphide (x10 -4 mol/l) 0.381 nr hardness ( m mol/l) 0.273 nr idroos & manage /journal of tropical forestry and environment vol. 2, no. 02 (2012) 13-26 23 4. discussion aquatic communities are good indicators of environmental quality (buss et al. 2003). results of bolgoda canal also convinces this fact as most of the organisms found in the canal were moderately pollution tolerant or pollution tolerant organisms (table 1). especially promacea bridgesi (apple snail) found in the canal reflects the quality of the stream as promacea bridgesi is an invasive pouch snail living in polluted environments and generally indicate nutrient enriched conditions and poor water quality. the lung and gill combination of the promacea bridgesi reflects their adaptation to habitats with oxygen poor water (brown, 2009). in the bolgoda canal nepa cinerea (water scorpions) was detected in sampling location 1 and 2. it has been documented that water scorpions can tolerate pollution for a certain range (brown, 2009) and is commonly found lurking in trash and mud in ponds and mellow, marshy streams. presence of water scorpion in the bolgoda canal is an indication of presence of moderately pollution tolerant species. presence of tubifex tubifex in the bolgoda canal water is also ideal indications of unclean water. kazanci, (1996) recorded that tubifex tubifex was found in the regions in which the organic pollution was high and the dissolved oxygen was low. thus, presence of tubifex tubifex is compatible with low values of do in bolgoda canal waters (table 9). the macroinvertebrates in waga stream (table 3) consists of psephenidae larvae, nymphs of plecopterans and ephimeropterans, and gilled snails like paludomous loricatus and paludomous zeylanicus which are categorized as pollution sensitive organisms (usepa, 1996). the presence of pollution sensitive bioindicators in waga stream indicates that the stream water is in good condition. according to the usepa, 1996 pti value of the bolgoda canal (table 2) was less than 20 indicating poor water qualities where pti value in waga stream (table 4) was 20-40 and further ensures fair water quality. the phytoplankton communities recorded in the bolgoda canal (table 5) during the study period were mostly pollution tolerant species. microcystis aeruginosa was the dominant algae in the canal during the study period and the presence of the actinatarum sp. indicates polluted status of water (manage, 2009). the shannon wienner diversity index (swdi) value is said to be greater than 3 in clean waters, ranging from 1 to 3 indicate moderately polluted waters and less than 1 in heavily polluted waters (trivedi, 1981).in the present study, mean swdi value of phytoplankton species in the bolgoda canal ranged between 0.674±0.36 to1.513±1.80 indicating heavily polluted statuses. from february to july2010 total phytoplankton counts reduced from 2033±0.19 cells ml -1 to 1309±0.29cells ml -1 (table 5) was accompanied by increase of mean swdi value from 0.674±0.36 to 1.513±1.8 respectively. it was detected that decrease of the dominant m. aeruginosa results in a higher swdi value, which shows that diversity of the phytoplankton community in the bolgoda canal is inversely proportional to density of m. aeruginosa. the waga stream has a community of clean water algae such as staurastrum sp, ulothrix sp, elaktothrix zonata (manage, 2009). the total phytoplankton numbers were found to vary from 1011±0.51 cells ml -1 to 1788±1.82 cells ml -1 . reduction in total counts is accompanied by increase in mean swdi value from 1.89±0.72 to 3.06±0.82 indicating the stream has a diverse phytoplankton community which confirms good water quality (table 6). according to ambient water quality standards for inland waters in sri lanka, published by the central environmental authority in 2001 the ph of the water should be 6.0 to 8.5 to sustain healthy aquatic life. the bolgoda canal waters had much less ph values and deviates from maintaining healthy aquatic life. favorable do levels for aquatic life should be at least 3 mg/l and in the bolgoda canal, do decreased to 2.88 mg/l (table 9) in february. the ec values and temperature of the bolgoda canal waters did not exhibit a great threat to aquatic life. idroos & manage /journal of tropical forestry and environment vol. 2, no. 02 (2012) 13-26 24 results of the waga stream imply that the water quality parameters of the stream was suitable to maintain a healthy aquatic life, where ph of the stream ranged between 6.02-6.25, ec ranged between 31.75±3.45 and do levels 6.99 ± 0.75mg/l showed suitability for healthy aquatic life. pca plot resulted classifying three sampling locations in the bolgoda canal according to their physico-chemical parameters, pti and swdi (figure 3). location 1 in bolgoda canal had high values of water temperature and ph with low pti and swdi. receiving of house hold waste and anthropogenic loading by location 1 is believed to have resulted in high temperature and ph and low macroinvertebrate and phytoplankton diversity. the second sampling location of the canal had high total nitrate, bod, alkalinity, orthophosphate concentration, ec and swdi values as the location 2 was used for cattle bathing and other animal husbandry activities and consequently received high nitrates and phosphates. thus, the location 2 was enriched with nutrients needed for algal growth which resulted in higher swdi values. in the present study location 3 was selected as a control site and the pca plot showed high total nitrate, high bod values together with high pti and swdi indicating the site is comparatively able to maintain a diverse group of pollution tolerant macroinvertebrates and polluted water phytoplankton community. pca ordination of the reaches according the 12 variables describing physico-chemical parameters, pti and swdi provided a strong discrimination of the three distinct groups in waga stream (figure 4). high temperature, conductivity, total nitrate, orthophosphate, bod, and alkalinity, in the location 1, is believed to have resulted due to effluents reaching from rubber factory resulting low pti and swdi values. location 2 showed similar physico-chemical parameter values to location 1, though high ph, low bod and temperature. household effluents reaching to the location 2 is believed to have resulted in high nitrate, orthophosphate, ec, and alkalinity values, though the bod levels were much less even without receiving much organic wastes in comparison to location 1. the third sampling location (location 3) of waga stream acted as a control site and the results of pca further convince this fact as high temperature and do values, with a high pti and swdi values were recorded in location 3. location 3 was able to maintain a diverse group of pollution sensitive macroinvertebrate group and clean water phytoplankton community in higher numbers as the high do levels in water favors the existence of pollution sensitive species. though, high bod values recorded in location 3 does not agree with other parameter values and organic wastes resulted by decay of macroinvertebrates in location 3 is believed to have resulted in this condition. regression analysis showed among the measured physico-chemical parameters, temperature, ph, do, nitrate concentration and bod had a significant positive effect on the pti value of the bolgoda canal and waga stream with a r 2 > 50% and significance level p< 0.05 (table 10). thus, these parameters can affect the abundance and distribution of pollution tolerant species and pollution sensitive species in bolgoda canal and waga stream respectively. regression analysis between physico-chemical parameters and swdi of bolgoda canal and waga stream (table 11) showed temperature, ph , do, nitrate and bod values had a significant effect on swdi values of bolgoda canal with a r 2 > 50% and significance level p< 0.05. bolgoda canal contained phytoplankton species which are dominant in polluted waters and had a low swdi value. thus, low ph, do and high nitrate loadings to the canal has reached for a state of eutrophication with a swdi less than 1 in certain months. in waga stream temperature, ph, do, nitrate concentration and orthophosphate concentrations had a significant effect with an r 2 > 50% and significance level p< 0.05 on the swdi.swdi values of waga stream ranged between 1.89 and 3.01. swdi >3 represents clean waters (trivedi, 1981) thus, the waga stream is a not a polluted water body. thus, the present study convinces that the physico-chemical parameters of bolgoda canal water are not up to the standard level to maintain healthy aquatic life. the poor quality of the water in the canal is suitable only for moderately pollution tolerant and pollution tolerant organisms where as waga stream owns good quality waters to sustain pollution sensitive organisms. idroos & manage /journal of tropical forestry and environment vol. 2, no. 02 (2012) 13-26 25 conclusion the physico-chemical parameters like temperature, ph, do, nitrate concentration, bod and orthophosphate concentrations of a water body have a significant effect on the pti and swdi value. pti, swdi and physico-chemical parameters of bolgoda canal and waga stream convinced that the bolgoda canal is suitable for pollution tolerant and moderately pollution tolerant organisms while waga stream waters are suitable for pollution sensitive organisms. thus, in the prediction of the health status of a water way it is important to analyze the biological component together with physico-chemical parameters as the physico-chemical parameters have a significant effect on the biological component of a water way. references batiuk, r.a., orth, r.j., moore, k.a., dennison, w.c., stevension, j.c., staver, l.w., carter, v., rybicki, n.b., hickman, r.e., kollar,s., bieber,s., and heasly ,p. 1992. chesapeake bay submerged aquatic vegetation habitat requirements and restoration targets : a technical synthesis.virginia inst. of marine science., gloucester point va united states, 258. brown, d., and czarneki , j , 2009.biological monitoring , introduction to volunteer water quality monitoring training notebook, missouri stream team, jefferson city , united states ,140-159. buss, d.f., baptista, d.f., silveira, m.p., nessimian, j.l ., and dorville, l.f.m. 2003. influence of water chemistry and environmental quality on the macroinvertebrate assemblages in a river basin in southeast brazil: hydrobiologia 481:125-136. central environmental authority, 2001. proposed ambient water quality standards for inland waters sri lanka. colombo, sri lanka: environment action 1 project (funded by adb). de lange, e. 1994. manual for simple water quality analysis.international water tribunal (iwt) foundation : amsterdam. duran m., 2002.monitoring water quality using benthic macroinvertebrates and physic-chemical parameters of bezhat stream, turkey: journal of environmental pollution 15 , 709-717. gannon, j. e., and stemberger ,r. s., 1978. zooplankton as indicators of water quality.trans. am.microscop. soc. 97, 16-35. gonçalves, b.f., and de menzes ,m.s., 2011. a comparative analysis of biotic indices that use macroinvetbrates to asses water quality in a coastal river of parana estate, southern brazil: biota neotrop 11, pg 4-5. gray n.f., 1994.water technologyan introduction for environmental scientist and engineers , viva books private ltd ,new delhi, 133-177 kazanci , n., and girgin , s.,1996. distribution of oligochaeta species as bioindicators of organic pollution in ankara stream and their use in biomonitoring, turkey kennish, m.j., 1992. ecology of estuaries : anthropogenic effects. crc press : boca raton. manage, p.m., 2009. training manual on role of nuisance algae and their detection in water supply projects in sri lanka, national water supply and drainage board, sri lanka. mcdonald, b., borden, and w., lathrop, j., 1990. citizen stream monitoring: a manual for illinois. illinois department of energy and natural resources,ilenr/re-wr-90/18. springfield, illinois. mendis, a.s.., and fernando, c.h., 2002.a guide to the freshwater fauna of ceylon. in (eds: fernando c.h. and weerewardhena sr) sri lanka freshwater fauna and fisheries. 51-59. palmer, c.m., 1959. algae in water suppliesus dept. of health, pub health service publications, cincinnati, the ohio journal of science, 27. presscott, g. w., 1970. how to know the fresh water algae, library of congress catalog in data, 2-89. ramakrishnan, n., 2003.bio-monitoring approaches for water quality assessment in two waterbodies at tiruvannamalai, tamilnaduindia, proceedings of the third international conference on environment and health, chennai, india, 374 – 385. idroos & manage /journal of tropical forestry and environment vol. 2, no. 02 (2012) 13-26 26 rosenberg, d.m., and resh,v.h., 1993.freshwater biomonitoring and benthic macroinvertebrates, chapman & hall, new york. silva , e.i.l.,namarathne ,s.y., weerasooriya ,s.v.r., and munaweera , l.,1996.water analysis user friendly field / laboratory manual, aj prints , dehiwala, sri lanaka. trivedi r.c., 1981. use of diversity index in evaluation of water quality, central board for the prevention and control of water pollution, new delhi. tudorancea, c., green, r.h., huebner, j.,1979. structure, dynamics and production of the benthic fauna in lake manitoba. hydrobiologia 64(1): 59-95. united states environmental protection agency, volunteer stream manual: a methods manual,1996 wetland site report and conservation management plan, bellanwila-attidiya marsh. 1993. 1-88. 24 presence of actinomycetes in agarwood tissues of aquilaria crassna: a preliminary study a.n.g.c.k. vidurangi1, d.s. manamgoda2, s.m.c.u.p. subasinghe1* 1. centre for forestry and environment, department of forestry and environmental science, university of sri jayewardenepura, nugegoda, sri lanka 2. department of botany, university of sri jayewardenepura, nugegoda, sri lanka date received:14th august 2022 date accepted: 28th september 2022 abstract agarwood is a valuable resin produced inside certain tree species of the family thymalaeaceae distributed in the asian region. agarwood production occurs as a defense mechanism when the trees are under physical or biological stresses. however, the formation of agarwood resins in significant extractable quantities due to natural stress conditions is rare; therefore, the farmers use various methods to induce its formation artificially. certain fungal species such as fusarium and aspergillus become more popular among them to produce high-quality agarwood. however, studies are rare on using other microbial organisms such as actinomycetes, which exhibit properties of both bacteria and fungi. among the agarwood-producing species, aquilaria crassna is one of asia's most commonly planted species for agarwood production. this species was introduced to sri lanka in 2012 for mid and lower elevations of the wet zone. due to the lack of studies on agarwood resin formation by non-fungal microbial methods, the present study attempted to identify the presence of actinomycetes species in agarwood resinous tissues of a. crassna. agarwood resinous tissue samples were collected from four plantations in the wet zone of the country. surface sterilized, small sized tissues were placed on starch casein agar medium and incubated at room temperature for ten days. using the morphological and microscopic characteristics, it was possible to identify nocardia, psuedonocardia, and three streptomyces species with varying abundance. the species level should be confirmed using molecular analysis, and their potential for agarwood resin formation inducement should be tested by re-inoculating to the healthy a. crassna trees. keywords: aquilaria crassna, agarwood, isolation, actinomycetes species 1. introduction aquilaria crassna of the family thymalaeaceae is commercially the most common agarwoodforming species in asia. though it is not native, plantation establishment using a. crassna in the low country wet and intermediate zones of sri lanka started in 2012 as a short rotation crop. the agarwood, which is dark resinous heartwood forms in this species, fetches a high value in the market as an ingredient for chinese medicine, perfume, and incense manufacturing (blanchette, 2003). the quality and the unique characteristics of agarwood resins vary due to its inducement method, region of growth and age of trees. the resin formation within trees due to natural causes is rare; therefore, the demand is higher than the available quantity on a commercial scale (akter et al., 2013). correspondence: upuls@sjp.ac.lk issn 2235-9362 online ©2022 university of sri jayewardenepura mailto:upuls@sjp.ac.lk vidurangi et al. / journal of tropical forestry and environment vol 12, no. 01 (2022) 24-30 25 agarwood resin is not present inside the tree during its growth, and its formation occurs due to pathological or non-pathological damage to the stem and roots. therefore the a. crassna plantations owners use different methods such as wounding to artificially induce agarwood resin formation (liu et al., 2013). however, those non-pathological inducement methods are not capable of producing good quality and large quantity of agarwood (cheong and choi, 2013). therefore, using biological methods such as certain fungal species became common among them to induce agarwood resin formation (subasinghe et al., 2019). those fungal species help to spread the induction through their hyphal growth in the tree to other regions of the stem and roots (turjaman et al., 2016). in its natural surroundings, a. crassna is highly exposed to a diverse group of microorganisms (nimnoi et al., 2011), and therefore it is essential to identify the potential endophytic microorganisms growing with aquilaria. endophytes are described as microorganisms that establish an endo-symbiotic relationship with plants, whereby plants receive ecological benefits from the presence of the symbionts, such as the ability to increase tolerance to stresses or plant growth promotion (hasegawa et al., 2006). some endophytic microorganisms have developed the ability to produce the same or similar bioactive substances such as pathogenesis-related enzymes or what their host plants produce that may be involved in a symbiotic association (strobel and daisy, 2003). changes in the activity of various enzymes in naturally infected trees indicate that they may be involved in the infection process and developing disease symptoms in agarwood trees. among the actinomycetes species associated with wood-forming areas, a few could exhibit pathogenesis while others seem to be saprophytic. many actinomycetes such as strptomyces promote plant growth and increase the biomass (lin and xiu, 2013). they also improve the soil condition by enhancing the nutrient recycling (abdelgawad et al., 2020). the morphology of actinomycetes is a fungi-like bacteria forming long filaments stretching through the substrate, which have an extensive impact on the environment by decomposing and transforming a wide variety of complex organic residues (malvia et al., 2014). endophytes such as actinomycetes colonize within plants and usually confer nutrition to the host plants and also prevent host plants being attacked by plant pathogens by producing a variety of lytic enzymes (nimnoi et al., 2010). they can also benefit plants by producing phytohormones, siderophores, antibiotics, and fixing nitrogen (bailey et al., 2006). though there are many studies in the literature on agarwood resin inducement by fungal species, the ability of actinomycetes species for the same is not commonly studied. therefore, the present study aimed to identify the actinomycetes species associated with the agarwood resinous tissues of a. crassna to provide preliminary recommendations that can be used to develop artificial inducers of agarwood resin formation at a commercial scale. 2. materials and methods 2.1 study sites and sampling of plant materials a. crassna plantations established between 2012-14 in four locations (handapangoda, horana, ingiriya, and mathugama) of the low country wet zone were selected for collecting samples (figure 1). all plantation locations are located in kalutara administrative district of the western province of sri lanka. handapangoda, horana and mathugama plantations are located in the wet-low 1a agro-ecological zone and ingiriya plantation is located in the wet-low 1b zone. the average annual rainfall of those zones are 2,800-3,200 mm and the average temperature is 25o-28o c. the soil type is red yellow podzolic. all plantations were established on lands with minimal slopes and the average diameter and height growth of the trees in those plantations are given in table 1. the ground was found to be covered with native grasses. young and mature aquilaria plantations were available only in the wet zone of sri lanka and therefore, 26 sampling was restricted that zone. sample collection was carried out during dry periods. those plantations have been managed under minimal treatments such as occasional weeding and application of organic fertilizer. table 1: average growth values ±se of a. crassna trees in the selected plantations. location diameter (cm) height (m) handapangoda horana ingiriya mathugama 20.8±1.0 17.6±0.4 15.0±0.9 20.1±0.7 10.6±0.2 9.0±0.3 9.6±0.3 11.8±0.6 agarwood resinous tissues formed due to abrasions and broken branches were collected from three trees of each plantation in a non-destructive manner. after identification of the wounds in the stem, a small sample was first tested to confirm the presence of agarwood resin which produces a strong pleasant aroma when burning. then those tissues were extracted using a sterilized sharp knife and a chisel. collected samples were sealed in sterilized polythene bags packed in a cool bag adjusted to 4-5oc temperature and then stored at the laboratory at 4±1oc until further analysis. figure 1: locations of the selected plantations for sample collection. 2.2 isolation of actinomycetes species the tissues were reduced to about 1×1×0.5 cm using sterilized sharp-edge cutters in the laboratory. they were surface-sterilized by placing in 10% sodium hypochlorite for 2 min followed by in 70% alcohol for vidurangi et al. / journal of tropical forestry and environment vol 12, no. 01 (2022) 24-30 27 another 2 min. then the samples were rinsed in sterilized distilled water twice (laurence, 2013). those were placed on a starch casein agar (sca) medium with 100 μg ml-1 of nystatin and cycloheximide to inhibit the fungal growth (wang et al., 1999). three replicates were prepared for each sample and incubated at 29±1o c for ten days under aseptic conditions to obtain the maximum colony appearances. actinomycetes colonies of different morphology were transferred to separate sca plates to isolate the pure actinomycetes cultures. microscopic examinations were used to identify the species level of the isolated actinomycetes species. 2.3 morphological observations and estimation of relative abundance observations of the growth of different actinomycetes colonies were carried out periodically for ten days using sub-cultures in sca medium. the morphological characteristics, viz., the colour of aerial mycelium and substrate and mycelium pattern, were visually studied. hyphae and conidia's shapes were identified using the trinocular microscope by preparing slide cultures for each isolation. for this, mycelia were carefully scraped to avoid damage to hyphae structures. the mycelia were then stained by methylene blue, and a cover glass was carefully placed on top to avoid bubble formations (nimnoi et al., 2010). relative abundance was calculated as a percentage of the total number of individual colonies belonging to one taxon divided by the total number of colonies belonging to all taxa (gong and guo, 2009). 3. results 3.1 morphological observations the results of the visual and microscopic morphological observations were used to identify the endophytic actinomycetes in the agarwood resinous tissue samples. altogether, it was possible to identify five isolates belonging to three genera (table 2). though the characteristics of streptomyces sp2 and 3 are similar in table 2, the colony appearance was different (figure 2). table 2: colony and microscopic characteristics of actinomycetes isolates. colony characteristics microscopic characteristics isolate name diameter (mm) am sm pg 3 ivory white branched and rod-shaped fragments nocardia sp. 3 dusty gray yellow long chains of spores pseudonocardia sp. 5 brown black brownblack spiral and long chains of spores streptomyces sp1. 4 ivory cream creamyellow spiral and long chains of spores streptomyces sp2. 5 ivory cream creamyellow spiral and long chains of spores streptomyces sp3 am=aerial mycelium colour; sm= substrate mycelium colour; pg=diffusible pigments released into the medium. 28 (a) pseudonocardia sp (b) nocardia sp. (c) streptomyces sp1 (c) streptomyces sp2 (d) streptomyces sp3 figure 2: pure cultures of actinomycetes colonies of different genera. 3.2 abundance of actinomycetes species and distribution in agarwood resinous tissues in different plantations a total of 27 actinomycetes colonies were isolated from 144 resinous tissues collected from a. crassna trees of four locations. however, the abundance of actinomycetes species in agarwood resinous tissues of a. crassna varied in four locations (figure 3). among them, a. crassna in ingiriya had the highest number (3) of actinomycetes species, and the lowest number was recorded in mathugama (1). nocardia and psuedonocardia were found only in horana and handapangoda plantations respectively, while streptomyces sp1 was found only in ingiria plantation. streptomyces sp2 was found as the most common which was in three plantations, viz. horana, handapangoda and ingiriya and sp3 was found in ingiriya and mathugama. further studies are needed, however, to identify the potential of those actinomycetes species to induce agarwood resin formation, which should be done by re-inoculating those species separately to healthy a. crassna trees. vidurangi et al. / journal of tropical forestry and environment vol 12, no. 01 (2022) 24-30 29 figure 3: abundance percentage of actinomycetes in the resinous tissues of a. crassna. 4. discussion we selected the starch casein agar medium for culturing actinomycetes species, which is capable of providing the saccharolytic organisms enough nutrients to produce their proteins and carbohydrates (hasegawa et al., 2006). these high nutrient media is essential to isolate actinomycetes species from terrestrial sources. though bredholdt et al. (2007) stated that the actinomycetes are one of the significant microbial dominant groups showing the capacity to survive in extreme habitats, their presence in agarwood resinous tissues of a. crassna was limited compared to the fungal communities. it could be due to the ability of the identified isolates to induce agarwood resin formation. else, it could be due to suppressing their growth by the fungi belonging to genera of aspergillus, cunninghamella, curvularia, fusarium, lasiodiplodia, xylaria etc. which are commonly found in agarwood resinous tissues in many countries (cui et al. 2013, mohamed et al., 2014, subasinghe et al., 2019). the present study identified the actinomycetes up to the genus level, which should be further identified by molecular analysis. the essential next step would be to test their ability to form agarwood resins in healthy a. crassna trees grown in diverse locations in sri lanka. references akter, s., islam, m.t., zulkefeli, m. and khan, s.i., 2013. agarwood production-a multidisciplinary field to be explored in bangladesh. international journal of pharmaceutical and life sciences, 2(1): pp.22-32. bailey, b.a., bae, h., strem, m.d., roberts, d.p., thomas, s.e., crozier, j., samuels, g.j., choi, i.y. and holmes, k.a., 2006. fungal and plant gene expression during the colonization of cacao seedlings by endophytic isolates of four trichoderma species. planta, 224(6): pp.1449-1464. bredholdt, h., galatenko, o.a., engelhardt, k., fjærvik, e., terekhova, l.p. and zotchev, s.b., 2007. rare actinomycete bacteria from the shallow water sediments of the trondheim fjord, norway: isolation, diversity and biological activity. environmental microbiology, 9(11): pp.2756-2764. blanchette, r.a., 2003. deterioration in historic and archaeological woods from terrestrial sites. art, biology, and conservation: biodeterioration of works of art. the metropolitan museum of art, new york, ny: pp.328-347. cheong, j.j. and do choi, y., 2003. methyl jasmonate as a vital substance in plants. trends in genetics, 19(7): pp.409-413. 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 horana handapangoda ingiriya mathugama nocardia sp pseudonocardia sp streptomyces sp1 streptomyces sp2 streptomyces sp3 30 cui, j., guo, s., fu, s., xiao, p. and wang, m., 2013. effects of inoculating fungi on agilawood formation in aquilaria sinensis. chinese science bulletin, 58(26): pp.3280-3287. gong, l. and guo, s., 2009. endophytic fungi from dracaena cambodiana and aquilaria sinensis and their antimicrobial activity. african journal of biotechnology, 8(5): pp.731-736. hasegawa, s., meguro, a., shimizu, m., nishimura, t. and kunoh, h., 2006. endophytic actinomycetes and their interactions with host plants. actinomycetologica, 20(2): pp.72-81. laurence, w.v.a., 2013. isolation and characterization of endophytes isolates from akar gaharu. research dissertation, universiti malaysia sarawak, malaysia. liu, y., chen, h., yang, y., zhang, z., wei, j., meng, h., chen, w., feng, j., gan, b., chen, x. and gao, z., 2013. whole-tree agarwood-inducing technique: an efficient novel technique for producing high-quality agarwood in cultivated aquilaria sinensis trees. molecules, 18(3): pp.3086-3106. malviya, n., yandigeri, m.s., yadav, a.k., solanki, m.k. and arora, d.k., 2014. isolation and characterization of novel alkali-halophilic actinomycetes from the chilika brackish water lake, india. annals of microbiology, 64(4): pp.1829-1838. mohamed, r., jong, p.l. and kamziah, a.k., 2014. fungal inoculation induces agarwood in young aquilaria malaccensis trees in the nursery. journal of forestry research, 25(1): pp.201-204. nimnoi, p., pongsilp, n. and lumyong, s., 2010. endophytic actinomycetes isolated from aquilaria crassna pierre ex lec and screening of plant growth promoters production. world journal of microbiology and biotechnology, 26(2): pp.193-203. nimnoi, p., pongsilp, n. and lumyong, s., 2011. actinobacterial community and diversity in rhizosphere soils of aquilaria crassna pierre ex lec assessed by rt-pcr and pcr-dgge. biochemical systematics and ecology, 39(4-6): pp.509-519. strobel, g. and daisy, b., 2003. bioprospecting for microbial endophytes and their natural products. microbiology and molecular biology reviews, 67(4): pp.491-502. subasinghe, s.m.c.u.p., hitihamu, h.i.d. and fernando, k.m.e.p., 2019. use of two fungal species to induce agarwood resin formation in gyrinops walla. journal of forestry research, 30(2): pp.721726. turjaman, m., hidayat, a. and santoso, e., 2016. development of agarwood induction technology using endophytic fungi. in agarwood (pp. 57-71). springer, singapore. lin, l. and xu, x., 2013. indole-3-acetic acid production by endophytic streptomyces sp. en-1 isolated from medicinal plants. current microbiology, 67(2): pp.209-217. abdelgawad, h., abuelsoud, w., madany, m.m., selim, s., zinta, g., mousa, a.s. and hozzein, w.n., 2020. actinomycetes enrich soil rhizosphere and improve seed quality as well as productivity of legumes by boosting nitrogen availability and metabolism. biomolecules, 10(12): p.1675. wang, y., zhang, z.s., ruan, j.s., wang, y.m. and ali, s.m., 1999. investigation of actinomycete diversity in the tropical rainforests of singapore. journal of industrial microbiology and biotechnology, 23(3), pp.178-187. chapter 3 27 cadmium induced adverse effects on fry of oreochromis mossambicus r. a. a. r. ranatunge, m. r. wijesinghe* and w. d. ratnasooriya. department of zoology, university of colombo, colombo 03. date received: 08-04-2011 date accepted: 28-09-2011 abstract this study investigates the effects of cadmium (cd) on fry of the mozambique tilapia oreochromis mossambicus using standard toxicity tests. fry were repeatedly exposed to five concentrations (0.002 – 2.0 mgl-1) of cd and survival, growth and swimming activity were monitored over 10 days. these trials revealed that all the tested concentrations significantly enhanced mortality of the fry with concentrations above 1.0 mgl-1 resulting in 100% mortality. mortality was positively related to the exposure level indicating dose-dependency. the lc50 1-10days ranged from 0.02 to7.26 mgl-1. fry exposed to cd also exhibited an increase in swimming activity in comparison to those that were not exposed indicating abnormal behaviour. nevertheless, there was no apparent growth retardation and gross morphological defects during the brief exposure period. these findings are significant because the lethal and sublethal effects in fry were also apparent at cd concentrations of 0.001 – 0.2 mgl-1, which are typically recorded in fresh waterbodies in sri lanka. keywords: cadmium, oreochromis mossambicus, survival, toxicity, sri lanka *correspondence: e-mail -mayuri@zoology.cmb.ac.lk tel-+94 071 446277 issn 2235-9370 print/ issn 2235-9362 online ©2011university of sri jayewardenepura journal of tropical forestry and environment vol. 01, no. 01 (2011) 27-35 28 1. introduction pollution of freshwater bodies is an issue that is being addressed extensively throughout the globe, heavy metals being one of the identified causes (shazili et al, 2006). the heavy metal cadmium (cd) assumes particular importance since it has been shown to reach undesirable levels in freshwater ecosystems such as reservoirs, streams and wetlands in many parts of the world. for instance, saeed and shaker (2008) has recorded high levels of cd in water and sediment in nothern delta lakes, egypt, while similarly high levels have been recorded by harikumar et al (2009) in wetland ecosystems in vembanad, india. as is the case elsewhere, in sri lanka too cd has become a frequent pollutant. bandara et al (2008) revealed that high cd concentrations were recorded in water and sediment in many of the cascade irrigation systems in sri lanka. anthropogenic activities such as metal production, the nickel-cadmium battery industry, electroplating and phosphorus fertilizer used in agriculture are responsible for the release of cd to the natural environment (kneip and hazen, 1979; yilmaz, 2009). cd contamination in fresh water is particularly alarming because it is known to be highly toxic to the exposed organisms leading to lethal and sublethal damage. cd causes direct morality in fish and other aquatic fauna (brown et al, 1994; irwin et al, 1997; joel and amajuoyi, 2009), reduces hatching rates (lugowska, 2007), retards growth and development (sharma and patino, 2009) and causes deformities and behavioural abnormalities. cd is known to disrupt physiological and biochemical processes in fish and amphibians (sehgal and saxena, 1987; zhang et al., 2007). cd also accumulates in organs and tissues (zyadah and baky, 2000; yilmaz, 2009) and therefore often results in biomagnification (dallinger et al., 1987). thus, assessing the toxicity of cd on aquatic fauna is of particular importance for sri lanka which supports many species of indigenous and endemic aquatic fauna. in the present study we investigate the impact of cd on the survival, growth and swimming activity of the fry of the mozambique tilapia oreochromis mossambicus. studies that assess the toxicity of heavy metals are important for a developing country such as sri lanka where water pollution has currently become a national issue. tilapia was selected as the study species because of its known tolerance to environmental stresses, availability as an aquarium species and the ease of rearing. the toxicity levels exhibited by this will enable us to predict hazards posed to other more sensitive species. toxicity will be assessed using three end points, i.e. mortality, growth and swimming activity. 2. materials and methodology 2.1 collection of larvae fry aged two weeks were obtained from the national aquaculture development authority, sri lanka located in dambulla. the collection of the fish from these breeding sites ensured that the experimental animals were free from exposure to heavy metals. 2.2 selection and preparation of test concentrations of cd the selection of the test concentrations were based on two factors. the field levels of cd in the water bodies of sri lanka was considered to be of primary importance since this would reflect the ranatunge et al./journal of tropical forestry and environment vol. 01, no. 01 (2011) 27-35 29 general levels that aquatic organisms are exposed to in the long run. however, since the present study involved empirical trials, it was also considered necessary to consider levels and durations of exposure used in previous exposure trials. accordingly, five test concentrations of cd, i.e. 0.002, 0.02, 0.2, 1 and 2 mgl-1 were selected. although much higher levels have been previously tested on fish (e.g. svecevieius, 2007), we considered it more relevant to ascertain effects induced by low cd concentrations since it better simulates field conditions. cadmium chloride (cdcl 2 ) was used in the present study following previous exposure experiments by garcia et al. (1999), sarnowski and witeska (2008), and vinodhini and narayanan (2008). hydrated cadmium chloride with the formula of cdcl 2 .2.5h 2 o = 228.34 [bdh laboratory reagents (99% purity), poole, england] was used to prepare a stock solution with distilled water. appropriate volumes of the stock solution were then used to prepare the required test concentrations. 2.3 experimental set up glass tanks of 22×15×15 cm size containing 2 l of tap water were used for the exposure trials. tap water was aged for 24 hours prior to filling the tanks to allow for the dissipation of chlorine. different volumes of the cdcl 2 stock solution was then added to each tank to obtain the relevant concentrations and mixed well using a glass rod to ensure homogeneity. each of the treatments and control (without the heavy metal) were maintained in triplicate. subsequently, 18 fry of o. mossambicus were randomly assigned to control or treatment tanks. standard body lengths of the fry were measured before they were placed in the tanks. the fry were taken on to a petri dish one at a time with a few drops of water and measured within about 30 seconds using a digital vernier caliper (comecta, electronic digital vernier caliper, barcelona, spain). the fry were fed daily with commercially available fish food pellets (san aquarium, colombo). the amounts of food added were determined by preliminary observations. an equal amount of the food was initially added to each tank (fifteen pellets: 30 ± 1 mg, n=10) but this was increased (to thirty pellets: 58 ± 0.9 mg, n=10) as fry grew. in subsequent additions, allowances were made for mortality with the amount of food being determined by the number of live individuals in each tank on a given day. the tanks were kept at room temperature (27.4 ± 0.04 oc) and exposed to the natural photoperiod of 12 hr light: 12 hr darkness. exposure trails were conducted for a period of ten days with cd concentrations being renewed every other day following modifications of the methods used by garcia et al. (1999), alattar (2005) and alwan et al. (2009). all tanks were aerated with a constant flow rate ensuring a continuous supply of oxygen for the fish throughout the trial. light intensity (li-250a light meter, biosciences, nebraska, usa), ph, temperature ( hanna, woonsocket, usa) and dissolved oxygen levels (hanna hi 9142, cluj-napoca, romania) of the tanks were measured every other day following water renewal. 2.4 monitored endpoints mortality of the fry was monitored daily. readings were taken at the same time on each day between 0900 1000 hrs. the dead fry were removed from the tanks. the surviving fry were closely observed to detect morphological aberrations such as tail curvatures or behavioural abnormalities such as alteration journal of tropical forestry and environment vol. 01, no. 01 (2011) 27-35 30 in speed of swimming, spinning and orientation. the initial (before exposure) and final (on day 10) body lengths were measured to monitor growth. the activity of fry was measured using a specific experimental set up used by sumanadasa et al., 2008, to record swimming activity. here the swimming activity of the fry was assessed using the number of crossings per animal in each tank. activity was recorded every other day (i.e. on days 2, 4, 6, 8 and 10) between 0830 to 1030 hrs. 3. results 3.1 effect on mortality overall the results show that the tilapia fry suffered high levels of mortality due to the exposure to cd. mortality at concentrations of 0.002 mgl-1 and above were significantly higher than that of the control (one-way anova and post hoc tests: f5,12 = 65.39, p<0.05). at the end of the 10 day exposure the fish in the two highest concentrations (1.0 and 2.0 mgl-1) suffered 100 % mortality (figure 1). fry in control tanks also suffered 20 % mortality. mortality was positively correlated with concentration indicating a significant dose-dependent response (pearson’s correlation r = 0.672, p<0.005). the lc 50 values obtained for tilapia fry over the 10 days were highly variable and ranged from 0.02 to 7.26 mgl1. the lc 50 values for 24, 48 and 96 hrs (standard) and 8 and 10 days were 7.26, 3.22, 0.09, 0.03 and 0.02 mgl-1 respectively. there was also a difference in the patterns of mortality over time i.e. the peak morality levels at the five concentrations occurred at different durations (two-way anova time * concentration; f45,120 = 2.76, p<0.05). interestingly, there were no gross morphological aberrations in any of the cd treated fry and control fry. note: means are from the three replicates.* indicates where mortality was significantly different from control (p<0.05) figure 1: cumulative mortality (± s.e.) of o. mossambicus fry, exposed to five concentrations of cd during a 10 day repeated exposure trial. p er ce nt ag e cu m ul at iv e m or ta li ty 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% 0.000 0.00z 0.0z0 0.z00 1.000 2.000 cadmium concentration (mgl-1) ranatunge et al./journal of tropical forestry and environment vol. 01, no. 01 (2011) 27-35 31 3.2. effect on larval growth the present study showed that exposure to the tested concentrations of cd (0.002 – 2.0 mgl-1) did not significantly affect the growth of o. mossambicus fry over a ten day period (table 1). the one-way anova confirmed that there was no significant difference in the initial or final lengths of fry between the control and treatment tanks (one-way anova: initial length f 5,318 = 0.07, p>0.05; final length f 3,91 = 0.95, p>0.05). growth impairments in larvae exposed to the two highest concentrations (1.0 and 2.0 mgl-1) could not be recorded due to 100 % mortality. table 1: mean body lengths (±s.e.) of o. mossambicus fry repeatedly exposed to five concentrations of cd over a period of 10 days. 3.3 effect on larval activity unlike in the case of growth, exposure to cd altered the swimming activity of o. mossambicus fry to some extent. a two way anova confirmed that there was a significant enhancement in activity levels over time across the different treatments and control (two-way anova: time * concentration; f 12,40 = 32.49, p<0.05). the fry that were not exposed showed a near constant and low rate of activity throughout the trial as indicated by the mean number of crossings per individual (figure 2). further, none of the cd treated fry exhibited spinning and alteration in orientation. 4. discussion the present study has shown that cd induces lethal and sub lethal toxicity in fry of the mozambique tilapia oreochromis mossambicus. this was apparent for two end points mortality and activity, but was not obvious for the third end point, growth. these results are particularly noteworthy given that the environmentally relevant levels of cd are capable of inducing high levels of mortality in fry of the tested species. in fact a concentration of 1.0 mgl-1 and above was capable of causing 100 % mortality of the fry, at least under empirical conditions. the findings of the present study are in agreement with those of others on amphibians and fish. for instance, in a similar study with cnesterodon decemmaculatus fry, cd concentrations of 0.05 and 0.1 mgl-1 respectively induced 86 % and 96 % mortality as a result of a seven day exposure to cd (garcia et al., 1999). as observed in the present study many authors have shown that heavy metal-induced mortality is also dose-dependent (e.g. heath, 1995; garcia et al., 1999). concentration (mgl-1) 0 0.002 0.02 0.2 1 2 initial body 9.80 10.31 10.14 10.35 9.83 10.28 length (mm) ± 0.13 ± 0.18 ± 0.20 ± 0.18 ± 0.15 ± 0.17 (n=54) (n=54) (n=54) (n=54) (n=54) (n=54) final body 10.78 10.85 10.54 9.95 length (mm) ± 0.21 ± 0.36 ± 0.28 ± 0.40 (n=41) (n=21) (n=25) (n=8) journal of tropical forestry and environment vol. 01, no. 01 (2011) 27-35 32 the lc 50 values in the present study were similar to those recorded in other studies. for instance, the 96h lc 50 of o. mossambicus was 0.05 mgl-1 (formicki et al., 2008) while a value of 0.09 mgl-1 was recorded in the present study. in fish, gills are the primary site of damage when exposed to high concentrations of cd over a short period. chung, 1983 has reported that respiratory failure and suffocation occurs due to the deposition of dead cellular material on gill surfaces. histopathological studies have confirmed this in the fresh water fish macropsobrycon uruguayanae exposed to 1.5 mgl-1 of cd for 15 days (randi et al., 1996). ionic imbalances have been recorded by heath (1995) which might have also contributed to the observed mortality in the fry. with regard to dose-dependency, a progressive decrease in plasma na has been shown to occur in tilapia exposed to cd (heath, 1995) which most likely induces dose-dependent mortality as that observed in the present study. since cd has the potential to accumulate within organs (e.g. nebeker et al., 1995) this factor might also trigger mortality at relatively high concentrations or over a relatively long exposure period. accumulation rates might be partly responsible for the variation in mortality rates in different concentrations of the heavy metal, with time. fry exposed to the two highest concentrations (1 and 2 mgl-1) suffered instant mortality, i.e within 24 hrs, while mortality was delayed in those exposed to lower concentrations probably because accumulation to lethal levels take longer. as opposed to mortality, cd exposure had no apparent effect on growth of o. mossambicus fry. in the case of tilapia growth impairments may not be very evident considering the brief period over which the trial was conducted. in fact other studies on fish conducted over a longer duration have shown that cd has the potential to cause growth reductions in fish. sarnowski and witeska (2008) demonstrated figure 2: effect of cd on swimming activity (mean number of crossings) of o. mossambicus fry repeatedly exposed to five different concentrations of cd during a ten day period. note: values show mean number of crossings per individual for 10 minutes. ranatunge et al./journal of tropical forestry and environment vol. 01, no. 01 (2011) 27-35 0.0mg/l 0.002mg/l 0.02mg/l 0.2mg/l 1.0mg/l 2.0mg/l day 2 day 4 day 6 day 8 day 10 duration of exposure1 st exposure n um be r of s w im m in g ev en ts p er i nd iv id ua ls /1 0 m in s 40 35 30 25 20 15 10 5 33 that larvae of cyprinus carpio l. which were exposed to 0.2 mgl-1 of cdcl 2 and monitored for 30 days were shorter compared to those of the control. in another study, shalaby (2007) has shown that 10 mgl-1 of cd induced growth retardation was observed in a 45 days trail with o. niloticus. with regard to alteration in activity levels by cd in the present study, all tested concentrations of cd induced hyperactive behaviour or accelerated swimming activity in the fry. such observations have also been made by giusi et al. (2005) for thalassoma pavo with cd exposure. it has been shown that 3 mgl1 of cd induces elevations in blood glucose levels in o. nilloticus (al-attar, 2005) most likely resulting in hyperactive behaviour. the brain has been identified as one of the target organs for cd in vertebrates (minami et al., 2001). thus it is possible that cd may have stimulated the cerebellum, which is responsible for the coordination of skeletal muscle movements (ganong, 1983). 5. conclusion the present study highlights the fact that cd at environmentally relevant concentrations of 0.02 – 0.20 mgl-1 has the potential to induce lethal and sublethal damage in fry of oreochromis mossambicus. this is particularly significant because the tilapia is considered to be a relatively hardy species. in the light of these findings it is necessary to strongly emphasize the need to have stringent measures for the discharge of contaminated effluents, from industries in particular, to the inland freshwater bodies of sri lanka so as to ensure that the concentrations of these harmful substances do not reach undesirable levels. acknowledgement we are grateful to the university of colombo for providing funds and facilities. we particularly acknowledge mr. j. r. a. c. jayakody and mrs. n. s. abeysinghe for their technical assistance. references al-attar, a. m., 2005. biochemical effects of short-term cd exposure on the freshwater fish, oreochromis niloticus. journal of biological sciences, 5(3), 260-265. alwan, s. f., hadi, a. a. and shokr, a. e., 2009. alterations in hematological parameters of fresh water fish, tilapia zillii, exposed to aluminium. journal of science and its applications, 3(1), 12-19. bandara, j. m. r. s., senevirathna, d.m.a.n., dasanayake, d.m.r.s.b., herath, v., bandara, j.m.r.p., abeysekara, t. and rajapaksha, k.h., 2008. chronic renal failure among farm families in cascade irrigation systems in sri lanka associated with elevated dietary cadmium levels in rice and freshwater fish (tilapia). environmental geochemistry and health, 30(5), 465-478. brown, v., shurben, d., miller, w. and crane, m., 1994. cadmium toxicity to rainbow trout oncorhynchus mykiss walbaum and brown trout salmo trutta l. over extended exposure periods. ecotoxicology and environmental safety, 29(1), 38-46. chung, k. s. 1983. lethal effects of cadmium in tropical fishes. bulletin of the japanese society of scientific fisheries, 49(10), 1565-1568. journal of tropical forestry and environment vol. 01, no. 01 (2011) 27-35 34 dallinger, r., prosi, f., segner, h. and back, h. 1987. contaminated food and uptake of heavy metals by fish: a review and a proposal for further research. oecologia, 73(1), 91-98. formicki, g., stawarz, r., lukac, n., putala, a. and kuczkowska, a., 2008. combined effects of cadmium and ultraviolet radiation on mortality and mineral content in common frog (rana temporaria) larvae. journal of environmental science and health part a, 43, 1174-1183. ganong, w. f., 1983. review of medical physiology. 11th edition. lange medical publications, los altos, california. garcia, m. e., cappelletti, c. a. and salibian, a., 1999. sublethal maternal pre-exposure of fish to cadmium. effect on the survival of the newly hatched alevins. archives of physiology and biochemistry, 107(2), 152-158. giusi, g., facciolo, r. m., alo, r., carelli, a., madeo, m., brandmayr, p. and canonaco, m., 2005. some environmental contaminants influence motor and feeding behaviors in the ornate wrasse (thalassoma pavo) via distinct cerebral histamine receptor subtypes. environmental health perspectives, 113(11), 1522-1529. harikumar, p. s., nasir, u. p. and mujeebu rahman, m. p., 2009. distribution of heavy metals in the core sediments of a tropical wetland system. international journal of environmental science and technology, 6(2), 225-232. heath, a. g. 1995. water pollution and fish physiology. lewis publishers, florida. irwin, r. j., mouwerik, m. v., stevens, l., seese, m. d. and basham, w., 1997. environmental contaminants encyclopedia cadmium entry. national park service, fort collins, colorado. joel, o.f., amajuoyi, c.a. 2009. evaluation of the effect of short-term cadmium exposure on brackish water shrimp-palaemonetes africanus. journal of appied. scences and environmental management, 13(4), 23 – 27. kneip, t. j. and hazen, r. e., 1979. deposit and mobility of cadmium in a marsh-cove ecosystem and the relation to cadmium concentration in biota. environmental health perspectives, 28, 67-73 lugowska, k. 2007. the effect of cadmium and cadmium/copper mixture during the embryonic development of common carp larvae, electronic journal of ichthyology, 2, 46-60. minami, a., takeda, a., nishibaba, d., takefuta, s. and oku, n., 2001. cadmium action in synapses in the brain. riken review, 35 nebeker, a. v., schuytema, g. s. and ott, s. l. 1995. effects of cadmium on growth and bioaccumulation in the northwestern salamander ambystoma gracile. archive of environmental contamination and toxicology, 29, 492-499. randi, a. s., monserrat, j. m., rodriguez, e. m. and romano, l. a., 1996. histopathologieal effects of cadmium on the gills of the freshwater fish, macropsobrycon uruguayanae eigenmann (pisces, atherinidae). journal of fish diseases, 19, 311-322. saeed, s.m., shaker, i.m. 2008. assessment of heavy metals pollution in water and sediments and their effect on oreochromis niloticus in the northern delta lakes, egypt, 8th international symposium on tilapia in aquaculture 2008. sarnowski, p. and witeska, m., 2008). the effects of copper and cadmium in single exposure or coexposure on growth of common carp (cyprinus carpio l.) larvae. polish journal of environmental studies, 17(5), 791-796. ranatunge et al./journal of tropical forestry and environment vol. 01, no. 01 (2011) 27-35 35 shalaby, a. m. e., 2007. effect of edta on toxicity reduction of cadmium in relation to growth, some haematological and biochemical profiles of nile tilapia (oreochromis niloticus). journal of fisheries and aquatic science, 2(2), 100-109. sehgal, r. and saxena, a. b. 1987. determination of acute toxicity levels of cadmium and lead to the fish lebistus reticulates. international journal of environmental studies, 29(2&3), 157-161. shazili, n.a.m., yunus, k., ahmad, a.s., abdullah, n. rashid, m.k.a. 2006, heavy metal pollution status in the malaysian aquatic environment, aquatic ecosystem health & management, 9(2), 137 145 sharma, b. and patino, r., 2009. effects of cadmium on growth, metamorphosis and gonadal sex differentiation in tadpoles of the african clawed frog, xenopus laevis, chemosphere, 76(8), 10481055. sumanadasa, d. m., wijesinghe, m. r. and ratnasooriya, w. d. 2008. effects of diazonian on larvae of the asian common toad (b. melanostictus, schneider 1799). environmental toxicology and chemistry, 27(11), 2320-2325. svecevieius, g., 2007. the use of fish avoidance response in identifying sublethal toxicity of heavy metals and their mixtures. acta zoologica lituanica, 17(2), 139-142. vinodhini, r. and narayanan, m., 2008. bioaccumulation of heavy metals in organs of fresh water fish cyprinus carpio (common carp). international journal of environmental science and technology, 5(2), 179-182. yilmaz, f., 2009. the comparison of heavy metal contaminations (cd, cu, mn, pb and zn) in tissues of three economically important fish (anguilla anguilla, mugli cephalus and oreochromis niloticus) inhabiting koycegiz lake – mugla (turkey). turkish journal of science & technology, 4(1), 7-15. zhang, y., huang, d., zhao, d., long, j., song, g. and li, a., 2007. long-term toxicity effects of cadmium and lead on bufo raddei tadpoles. bulletin of environmental contamination and toxicology, 79, 178–183. zyadah, m.a., baky, t.e.a., 2000. toxicity and bioaccumulation of copper, zinc, and cadmium in some aquatic organisms, bulletin of environment contamination and toxicology, 64:740-747. journal of tropical forestry and environment vol. 01, no. 01 (2011) 27-35 dharmadasa et al. /journal of tropical forestry and environment vol. 7, no. 02 (2017) 21-30 21 degradation of microcystin lr, oxytetracycline and amphicillin by four native bacteria species p.s. dharmadasa, g.y. liyanage and p.m. manage* centreforwaterquality andalgaeresearch,department ofzoology, university ofsrijayewardenepura, srilanka date received: 07-08-2017 date accepted: 02-12-2017 abstract pollution reaches its most serious proportion in past few decades and adverselyeffect on animals and human health. reduction of pollutant in the environment take place with microbial metabolism and remediation studies by microbes have proved their feasibility on clean up the contaminated environment. thus, the present study reports the biodegradation of micocystins (mc-lr) and antibiotics [oxytetracycline (otc) and ampicillin (amp)] by bacillus cereus, enterobacter ulcerans, enterobacter sp. and micrococcus sp. strains which were previously reported as potential crude oil degraders. a 0.5 ml of overnight starved bacterial suspensions was introduced into medium containing antibiotic (otc, amp) at 60 µg/ml and microcystin-lr at 10µg/ml respectively. triplicate samples were incubated at 280c while shaking at 100 rpm. a 0.5 ml of aliquots was removed at 2 days interval for a period of 14 days and analysis was done by high performance liquid chromatography (hplc). the highest degradation of mclr was shown by micrococcus sp. (97%) where as other stains; e. ulcerans (96 %), enterobactor sp. (95 %) and b. cereus (88%) also showed comparative high degradation after 14 days of incubation. b. cereus, enterobacter sp. and micrococcus sp. were identified as amp resistance bacteria and degraded amp at 81%, 22% and 39% respectively. it was found thatb. cereus was resistance to otc and showed 56% reduction at 14 days of incubation.the results of the present study revealed that the bioremediation potential of harnessing microbes can cleanup of pollutant in the environment and use as ecofriendly tool for removal of environmental pollutants. keywords:bacillus cereus, enterobactersp., enterobacter ulcerans, micrococcus sp.,antibiotics, microcystin 1. introduction in the last few years a large number of ecosystems have changed due to anthropogenic activities. petroleum hydrocarbons, microcystin, pharmaceuticals are different type of toxicants in the environment and have become one of the most serious environmental problems around the world(fereidoun et al., 2007). these contaminates can accumulate via food chain and persist in the environment for a long time. those pollutants reaches its most serious proportion in the densely settled urban-industrial centers of more developing countries (kromm, 1973; havens et al., 2003). *correspondence: pathmalal@sjp.ac.lk tel: +94 714463908 issn 2235-9370 print/issn 2235-9362 online © university of sri jayewardenepura 22 occurrence of pharmaceuticals, especially antibiotics in the aquatic environment is a wellestablished issue and has become a matter of both scientific and public concern (allen et al., 2010). the introduction of these compounds into the environment through anthropogenic sources can constitute a potential risk for aquatic and terrestrial organisms. although present at vestigial levels, antibiotics may cause resistance in bacterial populations, making them ineffective in the treatment of several diseases (baquero et al., 2008; liyanage and manage, 2016 c). several studies have reported the occurrence of antibiotic residues in aquatic ecosystems: surface waters, drinking water, water treatment plant effluents and hospital wastewaters (berglund et al., 2014; liyanage and manage 2015 c, 2016 b). further, over the past several centuries, nutrient enrichment in water, particularly nitrogen and phosphorus, associated with urban, agricultural and industrial development, has promotedincreaseof cyanobacteria which cause eutrophication. this condition favors the mass occurrence of cyanobacterial blooms where cyanobacterial cells grow exuberantly, and reach more than 10,000 cells per milliliter (manage et al., 2009).cyanobacteria are the distinct group of bacteria which are photosynthetic and produce several metabolites. these metabolites include several endotoxins known to be cyanotoxins which are commonly found during blooms of cyanobacteria (manage et al.,2010). cyanobacteria may produce toxins such as hepatotoxic peptides, neurotoxic alkaloids and dermatotoxic phenolic compounds, in addition to lipopolysaccharides (sivonen et al., 1990). microcystinis a group of cyclic heptapeptidehepatotoxins, which are produce by some strains of cyanobacteriaum, microcystis spp., anabaenaspp., oscilatoriaspp.(romanowska-duda et al., 2002). these substances are natural endotoxins and release into water in high concentration when cell lysis takes place. (manage et al., 2000;romanowska-duda et al., 2002). cell lysis occurs under stress, mostly because of natural mortality or algaecide treatments. this cyclic heptapeptide causes serious damage to liver architecture, cellular organelles and reorganization of microfilaments. they inhibit the activity of protein phosphate 1 and 2a and act as tumor promoters(zhao et al., 2006). the mechanical and chemical methods that are used to remove antibiotics and microcystin from contaminated sites have limited effectiveness and are not accessible to all parts of the world due to high operating and material costs (liyanage and manage 2016 b, idroos and manage, 2014, manage et al., 2009).bioremediation is one of the most promising technologies for the treatment of antibiotics and microcystin as it is cost effective and identified as the best alternative eco-friendlymethod (liyanage and manage, 2015 b., manage et al., 2009). in bioremediationspecific bacteriause to remove either specific type of contaminant or different type of contaminants. a number of studies have reported biological degradation of microcystin in samples collected from lakes and sediments (manage et al., 2009; manage et al., 2010), but only a few bacterial strains with the ability to degrade microcystins have been isolated and characterized. for instance, many of the mc degraders are reported as sphingomonasor sphingomonas. until manage et al. (2009), identified mc degrading gram-positive actinobacteria, all of the mc degraders had belonged to gram-negative proteobacteria. in degradation of antibiotics; ding et al (2016) reported the tolerance of acinetobacter, stenetrophomonasmaltophilia and aeromonasveronii to otc in freshwater environments of ireland and england. maki et al., (2006) has isolated flavobacterium strains responsible for the degradation of a group of antibiotics including otc and amp. liyanage and manage (2016a; 2015a.) reported the antibiotic resistance activity by bacterial strain enterococcus sp., acinetobacter sp. thus, present study was focused on the microcystin and antibiotics degradation feasibility of bacillus cereus, enterobacter sp., micrococcus sp. and enterobacter ulcerans stains, since very limited information is available regarding multiple pollutant degradation ability of bacteria in sri lanka. these four stains were previously reported to be degraders of crude oil (liyanage and manage, 2016b). dharmadasa et al. /journal of tropical forestry and environment vol. 7, no. 02 (2017) 21-30 23 2. material and method 2.1 chemicals and reagents otc and amp standards, hplc and bacteriological grade chemicals were purchased from sigma aldrich, usa. 2.2 preparation of bacterial cultures each bacterial stain was transferred into 5ml of liquid luria bertani (lb) medium and incubated 28oc. then followed centrifugation to remove carbon source from the lb media and then the bacteria suspension was subjected to the starvation procedure, in phosphate buffer solution (pbs). thereafter equalized the turbidities of the bacteria suspension at a 590=0.35 (manage et al., 2009; liyanage and manage 2016). 2.3 microcystin degradation a 0.5 ml of starved, equalized bacterial suspension was inoculated into filtered sterilized lakewater containing microcystin at a final concentration of 10µg/ml. the treated flasks were incubated at 28oc while shaking at 100 rpm. 0.5ml ofsubsampleswerecollectedattwodaysintervalsforaperiodof14days.thenthesubsamples were centrifuged (12000 rpm)and the supernatantofeachsamplewassubjected toimmediatefreezing and stored at -20°c (manage et al., 2010). then the frozen samples were freeze-dried and reconstituted in 1ml of 100% aqueoushplcgrademethanolandsubjectedtothehplcanalysis (idroos and manage, 2014).the control was treated in the same manner as the experiment without bacterial inoculation. all the experimentswere done for each tested bacterial strain. 2.4 analysis of mc-lr by hplc mc-lr analysis was carried out by using the hplc system consisting of agilent 1200 series following the modified method of manage et al (2009). the injected volume was 25ul at 30o c. the c18 column was used and the eluents solvent were deionized water – 0.05% trifluoroacetic acid (tfa) and acetonititrile – 0.05% trifluoroacetic acid (tfa). concentration of mc-lr was determined by calibration of the peak areas in 200-330 nm. thehplc method hasadetectionlimitof0.5μg/ml and mc-lr recovery was obtainedgreaterthan90% (manage et al., 2010). 2.5 antibiotic degradation experiment for bacteria isolates a 0.5μl of equalized bacterial suspension was inoculated into filter-sterile freshwater, containing antibiotic at a final concentration of 60µg/ml respectively. all flasks were incubated at 28°c with continuously shaking at 100 rpm. a 0.5ml of sub samples were collected at two days intervals for a period of 14 days (liyanage and manage 2016 b). then the subsamples were centrifuged (12000 rpm) and supernatant of each sample was subjected immediate freezing and stored at -20°c. then the frozen samples were freeze-dried and reconstituted in 1 ml of 100% aqueous hplc grade methanol and subjected to the hplc analysis. control samples were prepared in triplicates following same protocol without bacteria inoculation (liyanage and manage. 2016 a). 2.6 minimum inhibition concentration the minimum inhibition concentration (mic) was determined by using an agar dilution method according to clsi guidelines (clsi.2015). 2.7 analysis of antibiotics by hplc the target antibiotics were quantified by using agilent 1200 series hplc equipped with diode array and fluorescence detector (fernandez-torres et al., 2010; liyanage and manage, 2016 b). the 24 injected volume was 20μl and chromatography was performed at 30o c. the mobile phase considered of a mixture of 0.1% glacial acetic acid in water (component a): 0.1% glacial acetic acid in acetonitrile (component b), 99:1 (v/v) was pumped in beginning at a flow rate of 0.7 ml/min for otc and tet. then followed linear elution gradient from 99% to 70% a in 25 min for the above antibiotics (liyanage and manage, 2016 b). concentration of each antibiotic was determined by calibration of the peak areas (at 280 nm for otc, 230 nm for amp) with that of an external standard. otc and amp recoveries were greater than 90%. 2.8determination of degradation rate and half-life time the degradation rate (h) of antibiotic/mc-lr by bacteria was calculated according tothe equation given bellow.half life time was calculated as the time taken to degrade 50% of antibiotic/mc-lr from the initial concentration. ℎ = 𝑙𝑛(𝐶/𝐶0)/𝑡 (1) where: c0=theconcentration of antibiotic/mc-lr at the beginning c=theconcentration of antibiotic/mc-lrat the end of the time interval trespective ly (manage et al., 2000). 3. results 3.1 microcystin-lr degradation kinetics figure 1: microcystin-lr (mc-lr) degradation by four bacterial strains after 14 days of incubation at 28 ᵒc ± 1ᵒc.when error bars are not shown standard error was less than the width of the symbol. (closed square; control, open circle; enterobacter sp., closed circle; b. cereus, open triangle; micrococcus sp., closed triangle; e.ulcerans). figure 1 showed the degradation of mc-lr by different bacterial strains. at 4 days of the incubation micrococcus sp. showed significant degradation, after that remaining constant until day 10 and thereafter decreased up to 97%. in contrast, enterobacter sp. maintained gradual decrease of mc-lr by day 8 of incubation and then initiated rapid degradation and ended up with achieving 98% degradation at 14 days of incubation. b. cereus only showed 82% of degradation even at 14 days of incubation. analysis m ic r o c y st in e c o n c e n tr a ti o n ( µ g /m l) incubation time (days) dharmadasa et al. /journal of tropical forestry and environment vol. 7, no. 02 (2017) 21-30 25 of the sterile controls showed no significant loss of mc-lr during the incubation and only 9% of decrease was detected may due to natural degradation and photo degradation effect. table 1:rate of degradation in mc-lr (given as mean value of triplicates). incubation time (days) degradation rate (d-1) enterobacter sp. b. cereus micrococcus sp. e. ulcerans 0 0±0.000 0±0.000 0±0.000 0±0.000 2 0.04±0.02 0.39±0.04 0.07±0.02 0.77±0.01 4 0.04±0.01 0.36±0.06 0.20±0.04 0.76±0.05 6 0.04±0.03 0.25±0.04 0.14±0.02 0.51±0.02 8 0.03±0.05 0.21±0.02 0.10±0.05 0.39±0.03 10 0.06±0.06 0.19±0.01 0.08±0.01 0.31±0.02 12 0.10±0.06 0.17±0.01 0.13±0.04 0.26±0.04 14 0.23±0.04 0.16±0.02 0.26±0.02 0.22±0.02 e. ulcerans showed the highest degradation rates at second day of incubation (0.77±0.01d-1) where as other strains showed low degradation rates during first two days. the degradation rates of enterobacter sp. were more or less constant (~0.04±0.02 d-1) up to day 10 and thereafter increased significantly up to 0.23±0.04d-1 at 14 days of incubation. b. cereus showed high degradation rate (0.39±0.04d-1) at the beginning and pronounced gradual decrease was observed onwards. micrococcus sp. showed higher degradation rate at end of the 14 days of incubation (0.26±0.02d-1). table 2:half life time of the mc-lr degradation by four bacteria strains. name of the bacteria half life time (days) enterobacter sp. 10.5 b. cereus 1.8 micrococcus sp. 3.7 e. ulcerans 1.3 e. ulcerans showed the lowest half life time of 1.3 days of incubation whereas b. cereus and micrococcus sp. showed 1.8 and 3.7 days respectively. a half life time of 10.5 days were detected for enterobacter sp. antibiotic degradation kinetics resistance of the bacteria to tested antibiotics table 3:antibiotic resistant against oxytetracycline and ampicillin by the tested bacterial strain. bacteria oxytetracycline (otc) ampicillin (amp) enterobactersp. + b. cereus + + micrococcus sp. + e. ulcerance (+) resistance(-) not resistance. 26 the bacteria resistance for the 60µg/ml concentration of otc and amp was recorded in table 3. only b. cereus was resistance to otcwhereasenterobacter sp., b. cereus, micrococcus sp. were recorded as resistance strain of bacteria for amp. figure 2: degradation of amp by three native bacterial strains, which are resistance to amp.when error bars are not shown standard deviation was less than the width of the symbol. (closed square; control, open circle; enterobacter sp., closed circle; b. cereus, open triangle; micrococcus sp.). figure 2 shows the degradation of amp (60 µg/ml) by bacterial strains during the incubation period. the amp resistance bacteria; b. cereus, enterobacter sp. and micrococcus sp. were showed 81%, 22%, 39% degradation of amp respectively at 14days of incubation. except b. cereus, other two bacterial strains were not showed a significant degradation thus it was not possible to calculate half life time during the incubation. half life time ofamp for b. cereus was 1.5 days and it was identified as a potential amp degrader among the bacteria strains employed in the present study. table 4:degradation rate of ampicillin in 60µg/ml (given as mean value of triplicate). b. cereus showed highest degradation rate (0.56±0.014 d-1) after two days of incubation while enterobactersp. and micrococcus sp. showed 0.02±0.007d-1 and 0.07±0.001 d-1degradation after two days of incubation respectively. a m p h ic il in e c o n c e n r a ti o n ( µ g /m l) incubation time (days) incubation time (days) degradation rate (d-1) bacillus cereus enterobacter sp. micrococcus sp. 0 0±0.000 0±0.000 0±0.0000 2 0.56±0.014 0.02±0.007 0.07±0.001 4 0.32±0.005 0.01±0.001 0.07±0.007 6 0.22±0.025 0.01±0.012 0.05±0.000 8 0.17±0.002 0.02±0.016 0.05±0.007 10 0.15±0.035 0.02±0.000 0.04±0.014 12 0.13±0.005 0.02±0.014 0.04±0.000 14 0.11±0.032 0.02±0.007 0.03±0.014 dharmadasa et al. /journal of tropical forestry and environment vol. 7, no. 02 (2017) 21-30 27 figure 3:degradation of otc by b. cereus. the error bars are not shown standard deviation was less than the width of the symbol. (closed square; control, closed circle; b. cereus). figure 3 showed the degradation of otc (60µg/ml) by b. cereus which was the only strain recorded to resistant againstotc. after 14 days incubation at 28±1oc the bacterial strains achieved 56% reduction of otc. table 5: rate of degradation in oxytetracycline by b. cereus (given as mean value of triplicate). days degradation rate ( d-1) 0 0±0.0000 2 0.04±0.004 4 0.02±0.004 6 0.07±0.002 8 0.06±0.006 10 0.07±0.002 12 0.06±0.003 14 0.06±0.009 low degradation rate was detected until day 4 of incubation (0.02±0.004d-1) where as it was increased up to 0.07±0.002 d-1 at 6th day of incubation. 4. discussion present study reports the biodegradation of some peptides (microcystins and some antibiotics) by four native bacteria species namely b. cereus, e. ulcerans, enterobacter sp. and micrococcus sp. the bacteria species were previously isolated from soil and water from three distinguishes cites where exposed to crude oil contamination with regular shipping activities and reported as degraders of crude oil (liyanage and manage, 2016). there is a growing number of isolated organisms reported as having the ability to degrade microcystin in water and so far the majority of bacteria appears belonging to the class proteobacteria(havens et al., 2003). however, manage et al., (2009) reported actinobacteria species as o x y te tr a c y c li n e c o n c e n tr a ti o n (µ g /m l) incubation time (days) 28 microcystindegraders. in the present study four bacterial isolates were shown significant degradation of microcystin-lr (mc-lr) at 14 days incubation. at 2 days incubation significant degradation of mc-lr was achieved by e. ulcerans (78%) and b. cereus (54%). at 4 days of the incubation micrococcus sp. (56%) showed significant degradation of mc-lr (figure 3). several studies were reported that bacillus spp. as micosystine degrading bacteria (zhoa et al., 2006). bacillus sp. utilize microcystineas sole carbon source and concentration of microcystine become zero within 7 days according to enzyme linked immunosorbant assay (elisa) and within 8 days according to protein phosphatase inhibition assay (alamri, 2013). accordingly the present study b. cereus degraded 88% of mc-lr after 14 days incubation and e. ulcerans (96%), enterobactor sp. (95 %) and micrococcus sp. (97%) have ability to degrade high amount of mc-lr(figure 3) compare to the other bacterial strains. out of the four strains e. ulcerans was shown short half-life (1.3 days) for mc-lr (table 1) compared to other three bacteria species employed in the present study. antibiotics are considered as emerging micro contaminants in water due to their potential adverse effects on ecosystems and human health. major negative effect of high concentration of antibiotics in the environment is developing antibiotic resistance bacterial species and those bacteria become more virulent (tan et al., 2012). antibiotic resistance can occur via three general mechanisms: prevention of interaction of the drug with target, efflux of the antibiotic from the cell, and direct destruction or modification of the compound(samah et al., 2006). the who has recommended a guide line value of less than 1 µg/l of antibiotic residues in the aquatic environment and less than 100µg/l in soil respectively (who, 2015). liyanage and manage (2015 c.) recorded that both water and sediment samples collected from wastewater discharge points in sri lanka contains higher otc (0.664-0.841 µg/ml) and amp (0.115-0.139 µg/ml) levels than the recommended values given by the who. therefore it causes an increase of antibioticresistant bacteria. accordingly present studyb. cereus is resistance to otc and the testedother bacteria species were resistance to amp except e. ulcerans. b. cereus, enterobactor sp. and micrococcus sp. showed 81%, 22%, 39% degradation of amp respectively. b. cereus was shown highest degradation and it was found that theb. cereuswas the only bacteria specie showed 56% reduction of otc at 14 days incubation. hence introduction, establishment and development of such ecofriendly, cost effective bio technologies for the country is timely important to help for the development of the country. the results of the present study revealed that the bioremediation technology with harnessing microbes will provide sound information for the cleanup of pollutant in the environment as ecofriendly tool for green solution. further studies with combination of biotechnology approaches are needed to development of eco friendly methods for cleanup environmental pollutants. 5. conclusions the highest degradation of mclr was shown by micrococcus sp. (97%) where as other stains; e. ulcerans(96%), enterobactor sp. (95%) and b. cereus (88%) also showed comparative high degradation after 14 days of incubation. b. cereus, enterobacter sp. and micrococcus sp. were identified as amp resistance bacteria and degraded amp at 81%, 22% and 39% respectively. it was found that b. cereus was resistance to otc and showed 56% reduction at 14 days of incubation. the results of the present study revealed that the bioremediation potential of harnessing microbes can cleanup of pollutant in the environment and use as eco friendly tool for removal of environmental pollutants. dharmadasa et al. /journal of tropical forestry and environment vol. 7, no. 02 (2017) 21-30 29 references allen, h. k., donato, j., wang, h. h., cloud-hansen k. a., davies, j. and handelsman j. 2010. call of the wild: antibiotic resistance genes in natural environments. nat. rev microbio. 8(4):251-259. alamri, s. a. 2013. biodegradation of microcystin by a new bacillus sp. isolated from a saudi freshwater lake. african journal of biotechnology, 9, 6552-6559. berglund, b., khan, g.a., weisner, s. e., ehde, p.m., fick, j. and lindgren, p.e. 2014. efficient removal of antibiotics in surface-flow constructed wetlands, with no observed impact on antibiotic resistance genes. science of the total environment. 476:29-37. baquero, f., martnez, j.l. and cantn, r. 2008. antibiotics and antibiotic resistance in water environments. current opinion in biotechnology.19(3):260–265. clsi guide lines. 2015. available at; http://clsi.org/wp-content/uploads/sites/14/2013/07/clsi-2015catalog.pdf ding, h., wu, y., zou, b., lou, q., zhang, w. and zhong j. 2016. simultaneous removal and degradation characteristics of sulfonamide, tetracycline, and quinolone antibiotics by laccase-mediated oxidation coupled with soil adsorption. journal of hazardous materials. 307:350-358. idroos, f.s. and manage, p.m. 2014. evaluation of antibiotic degrdation feasibility of bacillus cereus and rahnellaaquatilisstrains , journal of environment and natural resources, thailand. 188-193. fernandez-torres, m.o., consentino, m.a., bello lopez. and larsen, j.l. 2010. simultaneous determination of 11 antibiotics and their main metabolites from four different groups by reversedphase high performance liquid chromatography-diode array -fluorescence (hplc-dad-fld) in human urine sample.talanta. 81:871-880. fereidoun, h., nourddin, m.s., rreza, n.a., mohsen, a., ahmad, r. and pouria, h. 2007. the effect of long-term exposure to particulate pollution on the lung function of teheranian and zanjanian students. pakistan journal of physiology. 3:1-5. havens, k.e., james, r.t., east, t.l. and smith, v.h. 2003. n: p ratios, light limitation, and cyanobacterial dominance in a subtropical lake impacted by non-point source nutrient pollution. environmental pollution. 122:379-390. kromm, d.e. 1973. response to air pollution in ljubljana, yugoslavia. annals of the association of american geographers. 63:208-217. liyanage, g.y. and manage. p.m. 2016 a. isolation and characterization of oil degrading bacteria from coastal waters and sediments in sri lanka. j.natn.sci.foundation sri lanka, 44 (4): 351 358 liyanage, g.y. and manage. p.m. 2016 b. risk of prophylactic antibiotics in livestock and poultry farms; a growing problem for human and animal health and for the environment. proceeding of 2nd environment and natural resources international conference. thailand. pg 20. liyanage, g. y., and manage, p. m. 2016 c. evaluation of amoxicillin and sulfonamide removal by bacillus cereus, enterobacterludwigii and enterobacter sp., environment and natural resources j., 14 (1): 39-43 liyanage. g.y. and manage. p.m. 2015 (a). presence of tetracycline and oxytetracycline resistant bacteria and resistant genes in effluent water of zoological garden, sri lanka. proceeding of 11th international academic conference on development in science and technology (iacdst2015). 11-14. liyanage. y. and manage. p.m. 2015 (b). evaluation of amoxicillin and sulfanomide removal by b. cereus, e. ludwigii and enterobacter sp. journal of environment and natural resources, 14: 4339-4343. liyanage, g.y., manage, p.m. and de alwis, a. (2015.c) study on the occurrence of antibiotic contaminations in the aquatic environment, sri lanka. international conference on multidisciplinary approaches proceeding, pg. 198. 30 maki, t., h. hasegawa, h. kitami, k. fumoto,munekage, y. and ueda. k. 2006.bacterial degradation of antibiotic residues in marine fish farm sediments of uranouchi bay and phylogenetic analysis of antibiotic-degrading bacteria using 16s rdna sequences. fisheries science., 72: 811 – 820. manage, p.m., chritine edwards and linda a lawton. 2009. biodegradation of microcystin lr by natural bacterial population. environmental research in asia terrapub, (2009)vol. 2 277-285 manage, p.m., c. edwards and lawton. l. 2010. "bacterial degradation of microcystin." interdisciplinary studies on environmental chemistry-biological responses to contaminants. terrapub: tokyo: 97-104. manage, p.m., zen`ichiro kawabata and shin-ichi nakano. 2000. algicidal effect of the bacterium alcaigenesdenitrificans onmicrocystisspp. aquatmicrobecol 22: 111-117. romanowska-duda, z., mankiewicz, j., tarczynska, m., walter, z. and zalewski, m. 2002. the effect of toxic cyanobacteria (blue-green algae) on water plants and animal cells. polish journal of environmental studies, 11, 561-566. sarmah, a. k., meyer, m. t., and boxall, a. b. 2006. a global perspective on the use, sales, exposure pathways, occurrence, fate and effects of veterinary antibiotics (vas) in the environment. chemosphere., 65(5): 725-759. sivonen, k., niemelä, s., niemi, r., lepistö, l., luoma, t. and räsänen, l. 1990. toxic cyanobacteria (blue-green algae) in finnish fresh and coastal waters. hydrobiologia, 190, 267-275. tan, z., tan, f., zhao, l. and li, j. 2012. the synthesis, characterization and application of ciprofloxacin complexes and its coordination with copper, manganese and zirconium ions. journal of crystallization process and technology, 2(02), 55. world health organization, 2015. global action plan on antimicrobial resistance. p.geneva: world health organization. available at: http://www.who.int/drugresistance/global_action_plan/en/. zhao, y.-y., hrudey, s. and li, x.-f. 2006. determination of microcystins in water using integrated solid-phase microextraction with microbore high-performance liquid chromatography— electrospray quadruple time-of-flight mass spectrometry. journal of chromatographic science, 44, 359-365. http://www.who.int/drugresistance/global_action_plan/en/ 2.2 preparation of bacterial cultures each bacterial stain was transferred into 5ml of liquid luria bertani (lb) medium and incubated 28oc. then followed centrifugation to remove carbon source from the lb media and then the bacteria suspension was subjected to the starvation procedure, in... 3.1 microcystin-lr degradation kinetics antibiotic degradation kinetics resistance of the bacteria to tested antibiotics microsoft word 5 timber species wijesinghe & de silva /journal of tropical forestry and environment vol. 2. no. 01 (2012) 36-47 36 conservation value of forest plantations: a study of four timber species in sri lanka m. r. wijesinghe*1 and v. r.de silva1 1 department of zoology, university of colombo, colombo 03, sri lanka date received: 23-10-2011 date accepted: 16-02-2012 abstract this paper assesses the potential of forest plantations in sri lanka consisting of teak, mahogany and two species of eucalyptus, to facilitate the conservation of biodiversity using two taxonomic groups, the plants and birds. their diversity in plantations at a harvestable age were compared with that of a natural forest. enumerations of plants and dbh/height measurements were conducted in quadrates, while avifauna was recorded along transects. results show that plantation forests supported a reasonably rich community of both plants and birds, including natives and endemics. a large proportion of species were common to both plantations and natural forests indicating that plantations hold a subset of forest species. the presence of plants of various height and girth classes together with the high diversity and evenness values indicate that, although timber plantations are initially established as mono-cultivations, they facilitate the colonization of additional species. these findings thus demonstrate that forest plantations could make a significant contribution towards biodiversity conservation. key words: biodiversity, birds, forestry, conservation value, timber plantations 1. introduction timber is one of the most important raw materials extracted from natural forests. the expansion of the human population and the resultant increase in the demand for this commodity has led to the destruction of large extents of natural forests in many parts of the world. the concept of forest plantations primarily evolved to meet the growing demand for timber. worldwide, forest plantations cover less than five percent of the land area (about 187 million ha), but are able to meet 20 percent of the wood demand (larsen, 2002). in addition to playing an important role in meeting the global timber needs, and also to some extent the demand for fuel wood, forest plantations offer a wide range of other benefits. plantations are ideal for sequestering carbon and hence could make a significant contribution towards mitigating adverse effects of global climate change (sedjo, 2001; stavins and richards, 2005). these man-made forests have been also used to stabilize fragile ecosystems such as sand dunes, and also for improving water quality and providing shelter for livestock (gunatilleke and gunatilleke, 1983; rosomon, 1994; fao, 2009). it is also becoming increasingly apparent that forest plantations have a high conservation value. forest plantations because they provide refuges for indigenous biotic elements, are frequently used to compensate for the loss of natural forests in both tropical and temperate countries (e.g. sample, 2003; barlow et al., 2007; butler, 2007, cartledge, 2008). correspondence: mayuri@zoology.cmb.ac.lk tel: +94 71446277 issn 2235-9370 print / issn 2235-9362 online ©2012 university of sri jayewardenepura wijesinghe & de silva /journal of tropical forestry and environment vol. 2. no. 01 (2012) 36-47 37 sri lanka is a tropical island nation endowed with natural forests rich in biodiversity. nevertheless, over the past few decades, trends in population expansion and economic development in the country have led to immense deforestation with the natural forest cover of 70 percent in 1900 having dwindled to less than 24 percent by 1992 (mahindapala, 2001). the remnant forests are severely fragmented and are threatened by encroachment and overuse (marambe et al., 2006). forest plantations in sri lanka were established in the 1870s, and at present cover nearly 93000 ha and consist mainly of teak (tectona grandis), mahogany (swietenia macrophylla) and eucalyptus species (forest department, 1999). since deforestation is one of the major causes of biodiversity loss in sri lanka (mahindapala, 2001), and since studies elsewhere have shown that forest plantations could support biodiversity, the present study attempted to assess the conservation value of these timber plantations. 2. methodology 2.1 the study species the four selected timber species, namely teak (tectona grandis), mahogany (swietenia macrophylla), eucalyptus microcorys and eucalyptus grandis are well established as plantation timber species in sri lanka. these species fetch a high economic value and are in high demand both in local and export markets. teak was first introduced to the country from the malabar coast in 1680 as a species of commercial importance (forest department, 1997). it is one of the outstanding timber species in the world on account of its valuable properties, notably durability, strength, moderate weight, stability and relative ease with which it can be processed. in sri lanka it is grown extensively in both the dry and intermediate zones. mahogany was planted under the protective cover of an already established plantation or under natural forests (thayaparan, 2000). its wood is used for decorative purposes and is grown in the intermediate and wet zones of sri lanka. eucalyptus was among the first three exotics to be introduced to sri lanka to be raised as a forest plantation species. in sri lanka there are currently over 30,000 ha of eucalyptus plantations. its wood was found to be very promising for use as railway sleepers and as industrial timber. both e. microcorys and e. grandis thrive in the hill country. 2.2 biodiversity assessments the present study was conducted in 2008-2009. three plantations over 10 ha in extent were selected for each of the four timber species from the two districts kurunegala and nuwara-eliya in sri lanka, in which these species are commonly grown. these plantations had been originally established as monocultures and are managed by the forest department of sri lanka. all plantations selected for the study were of a harvestable age i.e. teak 30 years, mahogany 40 years and the two ecucalyptus spp. 25 years. four natural forests, one each for the four timber species, that was state protected and in close proximity to the timber plantations, was selected as the control site for comparing biodiversity. these natural forests are kandapola and ohiya in the nuwara eliya district and maragala kanda and galagedara in the kurunegala district. in each of the plantations vegetation surveys were conducted in five 10 x 10 m quadrates (n=15 per timber species), randomly placed within the plantations but separated by a distance of at least 50 m. all individuals (other than those with dbh below 5 cm) were enumerated, and the dbh and height recorded. five quadrates each were surveyed in the four natural forests. birds have been often used as indicators of human disturbance and habitat suitability (canterbury et al,. 2000; francl and schnel, 2002). thus in the present study birds were selected as the indicator group to assess the conservation value of the forest plantations for fauna. recording of avifauna was conducted along transects placed in the vicinity of the vegetation enumeration quadrates. five 200 m transects (n=15 per timber species) were marked and birds observed or heard at 10 m intervals along transects were recorded. at each point recording was conducted for 10 minutes. transects were walked on two days and twice a day i.e. between 0630 and 0930 hrs and between 1500 and 1800 hrs. five transects were also surveyed in each of the natural forests. wijesinghe & de silva /journal of tropical forestry and environment vol. 2. no. 01 (2012) 36-47 38 for both plants and birds, species lists were constructed and the shannon weiner diversity indices h’= -∑ pi.log pi where pi is the proportional abundance of each species were calculated separately for both plantations and the adjacent natural forests. evenness values (j’=h'/h) where h = log s and s is the number of species found in the plantation/forest was also calculated. 3. results overall, the results of the present study revealed that the plantation forests of all four timber species supported a considerable number of species of both plants and birds, although lower than that observed in the adjacent natural forests. considering plant species, the plantations on average supported half the number of species as the respective natural forests. the plant species in the plantations contained trees and herbaceous species. another noteworthy fact with regard to floristic composition is that plantation forests also supported a high number of endemic species (table 1). the endemics recorded in the plantations are given in appendix 1. in the case of teak, mahogany and e. grandis, over 90 per cent of the endemics recorded in natural forests were also recorded in plantations. with the exception of mahogany, all species recorded in plantations were also recorded in the natural forest. trends in abundance show that the mean abundance of plants in the four natural forests was approximately two to three folds higher than that in plantations (table 1). nevertheless it is apparent that plantations support a large density of plants which contained saplings of tree species. despite the differences in species richness and abundance in flora between natural forests and forest plantations striking differences were not evident with respect to diversity. apart from e. grandis where the most pronounced difference in diversity was evident, the diversity in other plantations was remarkably high (over 0.90). this together with the high evenness values for all timber species reveals uniform distribution with low numbers of dominant species indicating that these plantations harbour a rich community of other types of floral species in addition to the artificially established timber species. table 1: species richness, abundance and the shannon-weiner diversity indices and evenness values (mean + standard errors) for flora of plantations containing the four selected timber species (pl) and for adjacent natural forests (nf). no. of transects teak mahogony e. microcorys e. grandis total species richness pl 15 20 34 10 15 nf 5 32 50 33 23 proportion of species shared with natural forest 100 % 38.2 % 100 % 100 % total no. of endemics pl 15 7 13 9 9 nf 5 9 13 17 11 mean abundance (per transect) pl 15 38.00 ± 1.79 62.27 ± 3.80 20.47 ± 1.82 25.67 ± 3.00 nf 5 90.80 ± 6.42 111.4 ± 7.10 69.00 ± 3.62 61.00 ± 3.97 shannon wiener diversity index pl* 15 1.07 ± 0.12 1.29 ± 0.02 0.91 ± 0.02 0.56 ± 0.05 nf 5 1.28 1.68 1.52 1.36 evenness pl* 15 0.86 ± 0.04 0.89 ± 0.02 0.97 ± 0.01 0.54 ± 0.07 nf 5 0.83 0.99 0.99 0.94 * mean for three plantations wijesinghe & de silva /journal of tropical forestry and environment vol. 2. no. 01 (2012) 36-47 39 figures 1 and 2 show the structure of plantations and natural forests in terms of height and dbh of the trees within the enumerated quadrats. significant differences in abundance between plantations and natural forests were evident in some height or girth classes (t-tests ; p<0.05). nonetheless, it is clear that the overall pattern of distribution of plants in different height and girth classes in the plantation and natural forests are near similar. this is particularly evident in the case of both teak and mahogany where the lower height and dbh classes contain a relatively high numbers of individuals. figure 1: mean abundance of plants (+ std. error) in each height class in both timber plantations (black) and adjacent natural forests (grey). similar trends were evident with avifauna. the species richness of birds was higher in natural forests than that of plantations but the magnitude of this disparity was much lower than that observed for flora (table 2). for instance, the number of bird species in teak, mahogany and e. microcorys plantations were over half of that recorded from natural forests. with the exception of e. grandis where only 50 % of the bird species was shared with the natural forests, all species in the other three timber plantations was also recorded from the natural forest. in comparison to plants, both natural forests and plantations supported a sparse community of endemics with most of the species recorded in forests being also present in plantations. as with species richness, the abundance of birds was higher in natural forests than in plantations but the difference in abundance was of a lower magnitude as that observed for plants. the diversity and evenness of birds in plantations were comparable to that in natural forests indicting that the species found were relatively evenly distributed in both habitats. the endemics recorded in the plantations are given in appendix 2. 0 10 20 30 40 50 60 70 80 a b u n d a n c e 0-10 10.1 20 20.1 30 30.1 40 40< height classes (m) teak 0 20 40 60 80 a b u n d a n c e 0-10 10.1 20 20.1 30 30.1 40 40< height classes (m) e. microcorys 0 20 40 60 80 a b u n d a n c e 0-10 10.1 20 20.1 30 30.1 40 40< height classes (m) e. grandis 0 10 20 30 40 50 60 70 80 a b u n d a n c e 0-10 10.1 20 20.1 30 30.1 40 40< height classes (m) mahogany wijesinghe & de silva /journal of tropical forestry and environment vol. 2. no. 01 (2012) 36-47 40 figure 2: mean abundance of plants (+ std. error) in each dbh class in both timber plantations (black) and adjacent natural forests (grey). 4. discussion the objective of this investigation was to assess the capacity of forest plantations containing four of the commonly grown timber species in sri lanka to facilitate the protection of the country’s biodiversity. with respect to the two taxonomic groups under consideration, i.e. plants and birds, the results of the present study indicate that forest plantations have a reasonably high conservation value supporting the claim that these anthropogenic habitats in addition to its main role as a timber source, has the potential to function as a refuge for biodiversity. the overall species richness and abundance of plants were lower in forest plantations than in the adjacent natural forests. this is to be expected since the plantations in comparison to natural forests are relatively young anthropogenic ecosystems, and are initially established as monocultures. this observation is consistent with those of other studies (singhakumara, 1995; yaron, 1998; rhett, 2007). nevertheless, the present study shows that anthropogenic forests could also support a relatively rich community of forest plants and birds. for instance, all bird species recorded in teak, mahogany and e. microcorys as well as a significant proportion of those in e. grandis, were shared with the respective natural forest. a similar trend was noted for the plants suggesting that plantations supported a subset of forest flora and fauna. furthermore, the anthropogenic habitats supported many endemic plants and some endemic birds enhancing their potential to act as refuges of biodiversity. with regard to plants, the fact that plantations supported species of plants of different height and girth is also noteworthy. these findings are especially significant given that these anthropogenic habitats are originally established as even-aged monocultivations, consisting plants of similar height and girth. the diversity of flora, to a 0 20 40 60 80 a b u n d a n c e 0-6 6.1 12 12.1 18 18.1 24 24< dbh classes (cm) teak 0 20 40 60 80 a b u n d a n c e 0-6 6.1 12 12.1 18 18.1 24 24< dbh classes (cm) mahogany 0 20 40 60 80 a b u n d a n c e 0-6 6.1 12 12.1 18 18.1 24 24< dbh classes (cm) e. microcorys 0 20 40 60 80 a b u n d a n c e 0-6 6.1 12 12.1 18 18.1 24 24< dbh classes (cm) e. grandis wijesinghe & de silva /journal of tropical forestry and environment vol. 2. no. 01 (2012) 36-47 41 large extent, governs the richness of faunal species (martin, 2001). the higher diversity of plant species in natural forests creates greater habitat heterogeneity in turn supporting a richer faunal community (ball et al., 1994). consequently, plantations in general supported a relatively lower diversity of plants and birds in comparison to the natural forests. similar observations have been noted by others (e.g. hartley, 2002; lindenmayer and hobbs, 2004). table 2: species richness, shannon-weiner diversity indices and evenness values (mean+standard errors) for birds in plantations containing the four selected timber species (pl) and for adjacent natural forests (nf). no. of transects teak mahogony e. microcorys e. grandis total species richness pl 15 7 18 6 10 nf 5 11 23 15 18 proportion of species shared with natural forest 100 % 100 % 100 % 50 % total no. of endemics pl 15 1 2 2 nf 5 1 4 4 abundance (mean per transect) pl 15 12.8 + 1.5 22.53 + 1.78 11.47 + 1.21 10.33 + 1.13 nf 5 22.2 + 0.56 30.40 + 3.64 17.60 + 1.50 19.8 + 2.35 shannon wiener diversity index pl* 15 0.81 ± 0.02 0.99 ± 0.09 0.73 ± 0.06 0.81 ± 0.05 nf 5 1.12 1.27 1.01 1.06 evenness pl* 15 0.93 ± 0.05 0.82 ± 0.79 0.92 ± 0.01 0.92 ± 0.01 nf 5 0.93 0.93 0.93 0.92 * mean for three plantations comparing the four timber species with respect to overall richness and abundance of flora, it is apparent that plantations containing eucalyptus species supported a relatively poor community of plants than teak and mahogany. binkly and stape (2004) noting similar trends attribute this species impoverishment to the rapid uptake of nutrients and water which prevents other species from becoming established. it is also said that the leaves of eucalyptus degrade slowly resulting in a lower amount of nutrients returning to the soil in the form of humus (wilson, 1992; martin, 2001). additionally, fao (1998) reports that eucalyptus has a visible and scientifically established allopathic effect on other plants due to the emission of toxic compounds. as with the plants, the eucalyptus plantations in comparison to mahogany and teak also harboured a lower abundance of bird species. bass et al. (1999) has documented that the abundance and diversity of mammals, birds and insects are considerably less in eucalyptus plantations. in addition to the loss of habitat heterogeneity, eucalyptus trees are not conducive for nesting birds because of the oily smell of the leaves (roberts, 2002). the extent to which forests plantations may contribute towards biodiversity conservation will depend, however, on how plantations are managed. frequent disturbance caused by short rotation, clear felling and herbicide spraying are reported to be detrimental to the biota inhabiting forest plantations (rosoman, 1994). adopting suitable silvicultural measures would not only accelerate the establishment of species of both flora and fauna but also mitigate other adverse environmental impacts such as soil erosion and nutrient depletion (gunatilleke and gunatilleke, 1990). plantations if established in grasslands or croplands, or in severely degraded areas will facilitate the colonization of additional species since planting of trees tend to increase the vertical complexity of the landscape. forest wijesinghe & de silva /journal of tropical forestry and environment vol. 2. no. 01 (2012) 36-47 42 plantations established in close proximity to natural forests would particularly enhance biodiversity (toma, 2004; kanowski, 2005). colonization of additional plants or animals could be also accelerated if indigenous tree species are grown intermixed with timber crops (webb et al., 1984). it has been reported that such measures would also increase the productivity of the plantations (bandarathilake, 1999). 5. conclusion the results of the present study emphasize the fact that forest plantations have the potential to function as a refuge for wild species. this is particularly so with teak and mahogany plantations than with the eucalyptus plantations which supported lesser numbers of both plants and birds. this is especially relevant for sri lanka, a small tropical island where a large proportion of its rich biodiversity is threatened as a result of the destruction and fragmentation of its natural forests. today many of the country’s natural forests exist as isolated fragments. forest plantations may be of special significance in such fragmented landscapes, since they could serve as potential habitat corridors that form critical links between isolated forest fragments (mackinnon et al., 1986). the role of these man-made ecosystems in biodiversity conservation should therefore not be overlooked. references ball, j.b., hirai, s. pandey, d. 1994. commercial environmental forestry integrating trees into landscapes for multiple benefits. forestry management 11:16-20 bandaratillake, h. m. 1999. administration report of the conservation of forests sri lanka for the year 1999. forest department. sri lanka. barlow, j. gardner, t. a., araujo, i. s. 2007. quantifying the biodiversity value of tropical primary, secondary, and plantation forests proceedings of the national academic of sciences of the united states of america 104 (47): 18555-18560. bass, s., higman, s., judd, n., mayers, j. nussbaum, r. 1999. the sustainable forestry hand book. earthscan publications ltd, london.191pp. binkley, d. and stape, j.s. 2004. beagle bay big tree country tropical timber plantation project fauna assessment survey. ecologia general, 21:35-42 canterbury, g. e., martin, m. e., petit, d. r., petit, l. j.,bradford, d. f. 2000. bird communities and habitat as ecological indicators of forest condition in regional monitoring, conservation biology, 14 ( 2): 544-558. cartledge, s. 2008. saving biodiversity in sarawak: tree plantations to protect borneo’s endangered environment,http://reforestation.suite101.com/article.cfm/saving_biodiversity_in_sarawak#ixzz0qw tu0rht fao 1998. report submitted to the regional expert consultation on eucalyptus. fao sri lanka, colombo. 277pp. fao 2009. state of the world’s forests, fao sri lanka. colombo. francl, k. e., schnell, g. d. 2002. relationships of human disturbance, bird communities, and plant communities along the land-water interface of a large reservoir environmental monitoring and assessment 73 (1): 67-93. forest department. 1997. the teak management plan, vol 1. ministry of agriculture land and forestry and the forest department, battaramulla. 76pp. forest department 1999. designing an optimum protected area system for sri lanka’s natural forests.. volume 1. forest department of sri lanka, battaramulla. gunatilleke, i.a.u.n., gunatilleke , c.v.s 1983. conservation of natural forests in sri lanka, the sri lanka forester, 16:40-45 wijesinghe & de silva /journal of tropical forestry and environment vol. 2. no. 01 (2012) 36-47 43 gunatilleke, i.a.u.n. and gunatilleke , c.v.s .1990. distribution of floristic richness and its conservation in sri lanka, conservation biology, 4:25 hartley, m. j. 2002. rationale and methods for conserving biodiversity in plantation forests, forest ecology and management, 155: 81-95. kanowski, , j., catterall, c. p. wardell, j. g. w. 2005. consequences of broadscale timber plantations for biodiversity in cleared rainforest landscapes of tropical and subtropical australia. forest ecology and management, 208 (359-372) larsen, j. 2002. forest cover shrinking (online). http://www.global forest watch.org. lindenmayer, d. b., hobbs, r. j. 2004. fauna conservation in australian plantation forests – a review. biological conservation119, 151-168 mackinnon, j., mackinnon, c., child, g., thorsell, j. 1986. managing protected areas in the tropics. iucn, gland switzerland. mahindapala, r. 2001. biodiversity planning on asia. chapter 17: sri lanka. marambe, b., pushpakumara, d. k. n. g., silva, p., rathnayake, h. b., vidanage, s. 2006. chapter report on impacts on biodiversity. the biodiversity secretariate, ministry of environment. colombo. 26 pp. martin, b. (2001) eucalyptus plantations; research, management and development. world scientific publishing co. pvt ltd. rhett a. b. 2007. in the amazon, primary forest biodiversity tops that of secondary forest, plantations. http://news.mongabay.com/2007/1111-amazon.html. roberts, n. 2002. prospects for australian plantations: business perspectives. proceedings of the conference in australia. rosoman, g. 1994. the plantation effect: an ecoforestry review of the environmental effects of exotic monoculture tree plantations in aotearoa, new zealand. sustainable forestry, 2: 323-343. sample, v. a. 2003. forest plantations as components in a global biodiversity conservation strategy: the role of developed, temperate-forest countries. xii world forestry congress. sedjo, r.a. 2001. forest carbon sequestration: some issues for forest investments. resources for the future, 25: 1 26. singhakumara, b.m.p. 1995. floristic survey in adam’s peak wilderness. sri lanka forest department of sri lanka, battaramulla. 156pp. stavins r. n., richards, k. r. 2005. the cost of u.s. forest-based carbpn sequestration. pew centre for clobal climate change, arlington. p. 52. thayaparan, s. 2000. management plan for mahogany mixed plantations in kegalle and kurunegala division of sri lanka, volume ii. forest inventory and management division, forest department of sri lanka, battaramulla. 112pp. toma, t. 2004. plantation activities and ecosystem conservation: criteria and indicators for biodiversity conservation. in okuda, pp. 157-160.t. and matsumoto, y.(eds.). kyoto mechanism and the conservation of tropical forest ecosystem: proceedings of the international symposium/workshop on the kyoto mechanism and the conservation of tropical forest ecosystem. tokyo, japan. isbn 4990-1797-3-0 webb, d.b., wood, p. j., smith, j.p.,henman, g.s. 1984. a guide to species selection for tropical and subtropical plantations. university of oxford, commonwealth forestry institute, oxford. 256pp. wilson, r.a. 1992. eucalyptus. paradigm and protagonist (the ceasa model). paper presented at the 2nd market pulp conference, vancouver. yaron, g. 1998. alternative land use options in the mount cameroon region: an economic analysis. a report prepared for the mount cameroon project and department for international development, nri, chatham, uk. wijesinghe & de silva /journal of tropical forestry and environment vol. 2. no. 01 (2012) 36-47 44 appendix 1 plant species richness recorded in plantation forests of the four timber species. species richness recorded in a natural forest (nf) situated in close proximity to the plantations are also given for comparison. species teak mahogany e. microcorys e. grandis p nf p nf p nf p nf acacia caesia √ acronychia pedunculata √ √ √ actinodaphne speciosa √ √ adenanthera pavonia adinandra lasiopetala √ allophylus varians √ √ alseodaphne semecarpifolia √ √ alstonia scholaris √ andidesma alexiteria √ ardiisa humilis √ √ √ √ ardisia missionis √ √ √ artocarpus heterophyllus √ artocarpus nobilis √ √ arundinaria debilis √ √ asparagas falcatus √ √ √ atalantia ceylanica √ √ berberis ceylanica √ √ √ bhesa ceylanica √ √ bridelia moonii √ callophyllum sp. √ callophylum walkeri √ √ √ √ √ canthium dicoccum √ √ carallia brachiata √ caryota urens √ √ casearia thwaitesii √ √ celtis timorensis √ chloroxylon swietenia √ cinnamomum ovalifolium √ √ √ √ √ cinnamomum zeylanica √ √ √ cinnamomum cappara coronde √ √ √ clerodendrum inerme √ connarus monocarpus √ √ √ croton laccifer √ cryptocarya wightiana √ delonix regia √ demos elegans √ √ dillenia retusa √ √ √ √ diospyros racemosa √ √ √ diospyros walkeri √ √ dipterocarpus zeylanicus √ elaeagnus latifolia √ √ √ elaecarpus glandulifer √ √ elaeocarpus serratus √ wijesinghe & de silva /journal of tropical forestry and environment vol. 2. no. 01 (2012) 36-47 45 species teak mahogany e. microcorys e. grandis p nf p nf p nf p nf elaeocarpus subvillosus √ √ eugenia rorundata √ √ √ euphobia decipiens √ √ euphobia longana √ √ √ eurga nitida √ √ eurya chinensis √ √ ficus exasperata √ ficus microcarpa √ √ √ filicium decipiens √ gaertnera vaginans √ √ √ garcinia cambogia √ garcinia morella √ garcinia spicata √ √ √ glochidion pycnocarpum √ √ √ √ glycosmis angustifolia √ goniothalamus gardenari √ √ √ gymneme laciferum √ gyrinops walla √ √ hedyotis dendroides √ hedyotis flavescens √ hedyotis gartmorensis √ √ hedyotis trimenii √ holarrhena mitis √ √ humboldtia laurifolia √ √ hunteria zeylanica √ √ ilex walker √ √ isonandra compts √ √ ixora sp. √ lasianthus oliganthus √ √ litsea glutinosa √ litsea ovalifolia √ √ √ mallotus albus √ mallotus philippensis √ √ mangifera indica √ √ mangifera zeylanica √ √ √ mastinia montana √ mastixia simplicifolia √ √ measa indica √ meliosma pinnata √ √ meliosma simplicifolia √ memecylon gracillium √ √ memecylon rostratum √ miclulia nilagirica √ microtropis zeylanica √ morinda citrifolia √ myristica ceylanica √ √ √ neolitsea cassia √ neolitsea fuscata √ √ √ wijesinghe & de silva /journal of tropical forestry and environment vol. 2. no. 01 (2012) 36-47 46 species teak mahogany e. microcorys e. grandis p nf p nf p nf p nf nothapodytes nimmoniana √ nothopegia beddomei √ pagiantha dichotoma √ √ piper sp. √ √ √ piper sylvestre √ piper zeylanicum √ √ √ √ polyalthia korinti √ √ pometia pinnata √ √ psychotria zeylanica √ rhododendron arboretum √ √ rourea minor √ √ rubus ellipticus √ salacia reticulata √ √ salacia reticulata √ salmalia insignis √ √ √ sarcococca brevifolia √ √ √ √ sarcococca zeylanica √ √ sarcococca zeylanica √ √ scyphostachys coffaeoides √ semecarpus coriacea √ √ semecarpus coriacea √ smilax sp. √ √ smilax zeylanica √ √ smilax zeylanica strebius taxoides √ √ swietenia macrophylla √ symplocos cochinchinensis √ √ √ √ √ symplocos cordifolia √ symplocos elegans √ √ symplocos obtuse √ √ sysygium revolutum √ √ √ √ syzygium rotundifolium √ √ syzygium umbrosum √ tarenna flava √ √ tectona grandis √ terminalia bellirica √ √ toddalia asiatica √ √ √ turpinia malabarica √ uncara elliptica √ √ vaccinium symplocifolium √ vitex altissima √ wijesinghe & de silva /journal of tropical forestry and environment vol. 2. no. 01 (2012) 36-47 47 appendix 2 avifaunal species richness in the three forest plantations of the four timber species recorded during the present study. the species of birds recorded in the adjacent natural forests have also been provided for comparison. birds teak mahogany e.microcorys e.grandis p nf p nf p nf p nf accipiter badius √ √ √ acridotheres tristis √ anthracoceros coronatus √ √ apus affinis √ √ √ √ bradypterus palliser *i √ cacomantis sonneratii √ √ √ centropus sinensis √ chalcophaps indica √ √ collocalia unicolor √ √ √ √ copsychus malabaricus √ √ √ √ coracina macei √ √ √ corvus macrorhynchos √ culicicapa ceylonensis √ cyornis tickelliae √ √ √ √ dicaeum erythrorynchos √ dicrurus macrocercus √ √ √ dinopium benghalense √ gallas lafayetii * √ √ √ √ hemiprocne coronate √ √ √ √ hemipus picatus √ √ √ hirundo daurica √ √ hypothymis azurea √ √ hypsipetes leucocephalus √ pycnonotus cafer √ lonchura kelaarti √ megalaima flavifrons * √ megalaima haemacephala √ √ √ megalaima rubricapilla √ √ √ √ muscicapa latirostris √ √ √ √ √ √ √ muscicapa sordid √ nectarinia asiatica √ √ √ ocyceros gingalensis * √ √ √ √ oriolus xanthornus √ orthotomus sutorius √ phylloscopus magnirostris √ √ √ pomatorhinus horsfieldii √ pycnonotus melanicterus √ √ pycnonotus penicillatus √ √ √ √ rhopocichla atriceps √ √ sitta frontalis √ √ √ √ √ turdus merula √ turdoides rufescens * √ zoothera spiloptera * √ √ √ zosterops ceylonensis * √ √ *endemic birds _____________________________________________ *correspondence: pandianmaha11@gmail.com issn 2235-9370 print/issn 2235-9362 online © university of sri jayewardenepura 12 diversity and threatened climber plants in tropical forests of courtallam hills, southern western ghats, india e. pandian* and p. ravichandran department of plant science, manonmaniam sundaranar university, tirunelveli, tamil nadu, india date received: 26-11-2019 date accepted: 14-12-2019 abstract investigated the distribution of climber and its conservation status in tropical forests of courtallam hills in southern western ghats of tamil nadu, india during 2017-2018. a total of five 1 ha plots were established, and all climber species ≥1 cm diameter at breast height (dbh) were counted, which resulted in a total of 81 climbing plant species that representing to 62 genera under 30 families. study plots revealed the most abundant climber species are jasminum flexile (oleaceae), salacia oblonga (celastraceae) and ziziphus oenopolia (rhamnaceae). the dominant climber species families in the study plots include apocynaceae (11 species), leguminosae (10 species), menispermaceae and vitaceae (6 species each), capparaceae and oleaceae (5 species each) and convolvulaceae (4 species). among 81 climber species, about 12 species are documented as threatened species of courtallam hills. the results of this investigation suggest that forest management and forest protection is important for in-situ conservation of liana diversity with the involvement of local community. keywords: climbing modes, conservation, threatened species, western ghats, courtallam hills 1. introduction lianas are woody climbers that are an abundant and diverse group of plants in tropical forests (schnitzer and bongers, 2002; yang et al., 2018), where they comprise up to 32% of woody stems and 35% of woody species richness (schnitzer et al., 2011; de walt et al., 2015). the liana begins their life as self-supporting plants (putz, 1984; caballe, 1998) and providing a valuable food source for the associated fauna, physically linking trees together, furnishing canopy to canopy access for arboreal animals, tree regeneration and increasing tree mortality (putz and mooney, 1991; schnitzer and bongers, 2002). the lianas are largely used by local communities especially those surviving in nearby areas (phillips, 1991; bongers et al., 2002 liu et al., 2004; 2005; ewango, 2010; muthumperumal and parthasarathy, 2013). the climbing plants are found in all types of forests and all over the world, a few of climber studies have been carried out in the western ghats (sarvalingam et al., 2011; sarvalingam and rajendran, 2012; 2016) and eastern ghats (reddy and parthasarathy, 2003; parthasarathy et al., 2004; muthumperumal and parthasarathy, 2009; seger and hartz, 2014) of forests, india. over the time period liana abundance has increased in various tropical forests in old-growth forests of western amazonia (phillips et al., 2002; foster et al., 2008), the guianas (chave et al., 2008) and central america (wright et al., 2004; ingwell et al., 2010; schnitzer et al., 2012; yorke et al., 2013). moreover, evidences of climber species dominance in certain forest ecosystems i.e. temperate (allen et al., 2007) and tropical (phillips et al., 2002; muthumperumal and parthasarathy, 2009; swaine and grace, 2007) are also attributed to climate change (malhi and wright, 2005). doi: https://doi.org/10.31357/jtfe.v9i2.4464 mailto:pandianmaha11@gmail.com pandian and ravichandran /journal of tropical forestry and environment vol. 9, no. 02 (2019) 12-20 13 the abundance, species diversity and distribution of lianas are explained by several abiotic and biotic factors, including total rainfall, seasonality of rainfall, soil fertility, forest canopy structure and disturbance regimes (addo-fordjour et al., 2009a; 2009b; 2012; dewalt et al., 2010; ibarra-manriquez and martinez-ramos, 2002; poulsen et al., 2005; schnitzer and bongers, 2002; schnitzer et al., 2005; toledo, 2010; vivek and parthasarathy, 2016). density of lianas (≥1.6 cm diameter) decreased with increasing altitude, whereas species richness was highest at intermediate elevations (parthasarathy et al., 2004). plant species richness and community composition may differ according to elevational gradient (trigas et al., 2013), disturbance (mohandass et al., 2015), and other environmental factors like climatic conditions (tielborger et al., 2014). lianas play a major role in many aspects of forest functioning such as different patterns of pollination, dispersal and phenological systems, provide several resources and important role in the protection of biological diversity (reddy and parthasarathy, 2006) and they are well documented, since its fundamentally importance in the functioning of ecosystems as competing with trees either directly or indirectly, and they act as key ecological components of whole forest in transpiration, forest regeneration and carbon sequestration (schnitzer and bongers, 2002). the climbing species reveal a diversity of climbing mechanisms (hegarty and caballe, 1991) which is the best productive system of climbers and its overcome the trees for sunlight where they spread out the branches over the trees canopies (campbell and newbery, 1993). the small-scale of floristic surveys provide an effective method to explore forest structure and plant species composition within tropical forest communities (castillo-campos et al., 2008; mohandass and davidar, 2010; refuge et al., 2016). however, climber communities have been neglected by most of studies, hence many of them emphasise greater attention on climber diversity only in recent years, particularly in india, because their conservation is threatened by anthropogenic disturbance from local communities residing beside the forest area and on the fringes of these reserves continue to be enormous (mehta et al. 2008). our study aim is to investigate the climber species diversity and their threatened status in tropical forests of courtallam hills, southern wastern ghats, india. 2. methodology 2.1 the study area the present research work was conducted in courtallam hills of southern western ghats (swg) in tirunelveli district of tamil nadu, india lies between 08.90211n" and 77.29772e" and 08.91093n" and 77.25842e" (figure 1). elevation range is around 500 m to 1,500 m and it has a diverse geographical and physical features such as hills and low plains, thorn-scrub jungles, rivers and cascades and thick inland forest. the mean daily maximum temperature is 30° c. the weather is quite hot in may and june and the maximum temperature sometime reaches 39° c. this region enjoys winter (december to march), summer (april to june), southwest monsoon (june to september) and northeast monsoon (october to november). the month of november generally receives maximum rainfall. species were identified using various regional floras (gamble and fischer, 1915; 1935; nair and nayar, 1986; hooker, 1872 to 1897). the composition of the soil in the courtallam area as recorded by nair and nayar, (1986) is as follows: 18.1% gravel; dark brown sandy loam; 19.5% silt; 5.5% clay; 75% sand; water holding capacity 58.8%; ph 6.1; total soluble salt content 0.003% and organic carbon 2.2%. 14 figure 1. map showing the location of courtallam hills of southern western ghats of india. enumeration of angiosperm climbing plants was carried in a total of 5 different forest plots to investigate the diversity and threatened climber plants species in tropical forests of courtallam hills during 2017-2018. five 1-ha plots (100x100 m) were inventoried in different tropical forest plots, these plots were subdivided into two contiguous plots (50x100 m). these sub-plots were again subdivided into fifty 10x10 m quadrats for the quantitative assessment of climber species. all climber species with ≥1cm diameter at breast height (dbh) were measured at 1.3 m above ground level and their climbing mode (putz, 1984) was recorded in the field itself and were classified into six categories viz. st: stem twiners; str-a: stragglers-armed; str-ua: stragglers-unarmed; tc: tendril climbers; rc: root climbers; and hc: hook climber. the threatened status of the climber species was confirmed with iucn red list and also the help of using available ret (rare, endangered and threatened species) data books and standard publications such as (nair and daniel, 1986; nayar and sastry, 1987; nayar and sastry, 1988; nayar and sastry, 1990; walter and gillet .1998; sarvalingam and rajendran, 2016). voucher specimens were collected for each species and identified with local floras (nair and nayar, 1986; hooker, 1872; 1897; parkinson, 1923). 3. results and discussion a total of 81 angiosperm climbing plants from 62 genera and 30 families were recorded in five 1 ha plots of courtallam hills southern western ghats of india (table 1). sarvalingam and rajendran (2016) reported a total of 285 climbing plant species belonging to 125 genera and 41 families from pandian and ravichandran /journal of tropical forestry and environment vol. 9, no. 02 (2019) 12-20 15 different forest types in the southern western ghats of tamil nadu, india and 60 liana species were recorded in maruthamalai hills of southern western ghats (sarvalingam and rajendran, 2012) of tamil nadu. however, muthumperumal and parthasarathy (2009) recorded a total of 175 climbing plant species that belong to 100 genera and 40 families in tropical forests of southern eastern ghats, india. seger and hartz (2014) also conducted in northern eastern ghats of forests where 170 liana species were recorded, representing 109 genera and 43 families from 210 grids. a total of 169 species belonging to 60 families were encountered in the cagarras islands natural monument (cinm) located offshore of rio de janeiro, brazil (bovini et al., 2014), while araujo and alves (2010) also reported 93 climbing plant species were recorded in land atlantic forest, northern brazil, moreover in upper guinean forests documented 746 species of climbers (jongkind and hawthorne, 2005). abundance and distribution pattern of lianas generally depends on abiotic factors such as elevation, rainfall and seasonality, soil fertility, and disturbance (gentry, 1991; balfour and bond, 1993; schnitzer and bongers, 2002; lu et al., 2009; pandian and parthasarathy, 2016). our study plots revealed that the most abundant species are jasminum flexile (oleaceae), salacia oblonga (celastraceae) and ziziphus oenopolia (rhamnaceae) which data was pooled for the all the plots (table 1). in other hand, pterolobium hexapetalum (caesalpiniaceae), secamone emetica (asclepiadaceae) and premna villosa (verbenaceae) were reported by muthumperumal and parthasarathy (2013) as most abundant species in the western ghats, while northern eastern ghats (seger and hartz, 2014) showed most dominant liana species such as acacia sinuata (mimosaceae), bauhinia vahlii (caesalpiniaceae), calycapteris floribunda (combretaceae) and combretum albidum (combretaceae). strychnos minor (loganiaceae) was dominant in the tropical dry evergreen forests (parthasarathy et al., 2004) on the coromandel coast of india, interestingly those species did not occur in our sites. the dominant climber speciose families in our sites include apocynaceae (11 species), leguminosae (10 species), menispermaceae and vitaceae (6 species each), capparaceae and oleaceae (5 species each) and convolvulaceae (4 species) etc (figure 2). this result accordance with seger and hartz (2014) who reported the most specious families, convolvulaceae (23 species), papilionaceae (22 species), asclepiadaceae (19 species) and cucurbitaceae (9 species) in northern eastern ghats of india. the common liana families are cucurbitaceae, papilionaceae, asclepiadaceae and convolvulaceae in maruthamalia hills of western ghats (sarvalingam and rajendran, 2012). the families such as smilacaceae, passifloraceae, menispermaceae, cucurbitaceae and convolvulaceae are totally dominated by plant species with a climbing habit (araujo and alves, 2010). in general, apocynaceae, anonaceae, combrataceae, fabaceae, loganiaceae and rutaceae lianas families were dominated in asian forest (cai et al., 2009; dewalt et al., 2006; mittermeier et al., 2004; muthukumar et al., 2006; muthuperumal and parthasarathy, 2010; sukumaran and raj, 2007; sarvalingam and rajendran, 2016). bovini et al., (2014) also reported, most dominated families are asteraceae (12), myrtaceae (12), fabaceae (11), euphorbiaceae (6), cactaceae (6), bromeliaceae (6), and poaceae (6 species each) at cagarras islands natural monument (cinm) located offshore of rio de janeiro, brazil. the most abundant liana species include the thorny stragglers, ziziphus oenoplia (rhamnaceae), acacia caesia (leguminosae), capparis brevispina (capparaceae), carissa spinarum (apocynaceae), toddalia asiatica (rutaceae), and the twiners jasminum flexile (oleaceae), pyrenacantha volubilis (icacinaceae), ventilago maderaspatana (rhamnaceae), morinda umbellate (rubiaceae) and jasminum angustifolium (oleaceae) (table 1). this result coincides with muthumperumal and parthasarathy (2009) who also reported, thorny stragglers pterolobium hexapetalum (caesalpiniaceae), lantana camara (verbenaceae), ziziphus oenoplia (rhamnaceae), and the twiners jasminum angustifolium (oleaceae), gymnema sylvestre, secamone emetica (asclepiadaceae) and aganosma cymosa var. cymosa (apocynaceae) in tropical forests of southern eastern ghats, india. 16 among 81 climber species, about 12 species are documented as threatened species which are acacia caesia (leguminosae), aganosma cymosa (apocynaceae), ampelocissus latifolia (vitaceae), aristolochia tagala (aristolochiaceae), asparagus racemosus (asparagaceae), capparis diversifolia (capparaceae), cayratia pedata (vitaceae), coscinium fenestratum (menispermaceae), derris scandens (leguminosae), hemidesmus indicus (apocynaceae), salacia oblonga (celastraceae) smilax zeylanica (smilacaceae) in courtallam hills (table.2). karuppusamy and ravichandran (2016) reported, a total of 486 woody plant species, of which 41 species are recorded as threatened species (iucn) in megamalai wildlife sanctuary in the southern western ghats of theni district, tamil nadu and sarvalingam and rajendran (2016) also reported list of the rare, endangered and threatened (ret) of climbers in the southern western ghats of tamil nadu, india. among the 81 species, few of the climber species (abrus precatorius, asparagus racemosus, cissampelos pariera, coccinea grandis, hemidesmus indicus, ichnocarpus frutescens and tylophora indica) which are using as a medicinal plant by local people, this result coincides with uma and parthipan (2015) in pazhayaru river bank of kanyakumari district, tamilnadu. sarvalingam and rajendran (2016) also reported in southern western ghats where few medicinal climbers are (aganosoma cymosa, aristolochia tagala and coscinium fenestratum) using for curing skin diseases, cough, fever, headache, diabetes, asthma, dysentery and poison bites. pictures of selected liana species are given in figures (3-7). plant binomial, family and voucher number of the 81liana species are listed in table 1. the enumerated climbing plants were classified into two category woody vines, the lianas (69 species) and herbaceous vines (12 species). seger and hartz (2014) who also classified into two catenaries of lianas, woody vines (128 species) and herbaceous vines (42) in eastern ghats of india. the present study recorded six climbing mode of lianas were recognized: stem twiners (47%) followed by stragglersarmed (24%), stragglers unarmed (9%), tendril climbers (14%), root climbers (2%) and hook climber (2.5%). this climbing mode of lianas were similar with muthumperumal and parthasarathy (2009) and seger and hartz (2014) in tropical forests of eastern ghats, india. several researchers have been reported that stem twiners were most common climbing plants in the different tropical forests (parthasarathy et al., 2004; kuzee and bongers, 2005; ghollasimood et al., 2012). only one climbing mode, the grapnel-like climber (rattans) which was reported from indian western ghats sites by muthuramkumar and parthasarathy (2000), did not occur in our study plots. 4. conclusion the climbers play an important role in the forest ecology and dynamics. a total of 81 climber species, 12 species were reported as threatened species in courtallam hills. many of climber species need effective care and proper conservation measures for their survival and long-term protection, because of forests are deteriorating under constant human activities. the present data of floristic diversity of climbers would be useful in species conservation and forest management and this data will be useful further scientific research for a global audience which is lead their effective protection. acknowledgement authors wish to thank dst-serb–n pdf (pdf/2015/000874) for financial support. reference addo-fordjour, p., anning, a.k., larbi, j.a. and akyeampong, s., 2009a. liana species richness, abundance and relationship with trees in the bobiri forest reserve, ghana: impact of management systems. forest ecology and management, 257:1822-1828. pandian and ravichandran /journal of tropical forestry and environment vol. 9, no. 02 (2019) 12-20 17 addo-fordjour, p., obeng, s., addo, m.g. and akyeampong, s., 2009b. effects of human disturbances and plant invasion on liana community structure and relationship with trees in the tinte bepo forest reserve. ghana. forest ecology and management, 258:728-34. addo-fordjour, p., rahmad, z.b. and shahrul, a.m.s., 2012. effects of human disturbance on liana community diversity and structure in a tropical rain forest, malaysia: implication for conservation. journal of plant ecology, 5:391-399. allen, b.p., sharitz, r.r. and goebel, p.c., 2007. are lianas increasing in importance in temperate floodplain forests in the south eastern united states? forest ecology and management, 242: 1723. araujo, d. and alves, m., 2010. climbing plants of a fragmented area of lowland atlantic forest, igarassu, pernambuco (northeastern brazil). phytotaxa, 8:1-24. balfour, d. and bond, w., 1993. factors limiting climber distribution and abundance in a southern african forest. journal of ecology, 93-100. bongers, f., parren, m.p.e. and swaine, m.d., 2005. forest climbing plants of west africa: intoduction. forest climbing plants of west africa: diversity, ecology and management. wallingford, oxfordshire: cab international, 5-18. bongers, f.j.j.m., schnitzer, s.a. and traore, d., 2002. the importance of lianas and consequences for forest management in west africa. bioterre, 59-70. bovini, m.g., faria, m., oliveira, r.r. and kurtz b.r., 2014. floristic diversity of the cagarras islands natural monument, rio de janeiro, brazil. check list, 10:366-373. caballe, g., 1998. self-supporting capacity of tropical lianas: growth strategies. canadian journal of botany, 76:1703-1716. cai, z.q., schnitzer, s.a., wen, b., chen, y.j. and bongers, f., 2009. liana communities in three tropical forest types in xishuangbanna south-west china. journal of tropical forest science, 252-264. campbell, e.j.f. and newbery, d.m., 1993. ecological relationships between lianas and trees in lowland rain forest in sabah, east malaysia. journal of tropical ecology, 9:469-490. castillo-campos, g., halffter, g. and moreno, c.e., 2008. primary and secondary vegetation patches as contributors to floristic diversity in a tropical deciduous forest landscape. biodiversity and conservation, 17:1701-1714. chave, j., olivier, j., bongers, f., chatelet, p., forgets, p.m., peter van der meer, norden, n., riera, b. and dominique, p.c., 2008. aboveground biomass and productivity in a rain forest of eastern south america. journal of tropical ecology, 24:355-366. dewalt, s.j., schnitzer, s.a., alves, l.f., bongers, f., burnham, r.j., cai, z., carson, w.p., chave, j., chuyong, g.b., costa, f.r.c., ewango, c.e.n., gallagher, r.v., gerwing, j.j., amezcua, e.g., hart, t., ibarra‐manríquez, g., ickes, k., kenfack, d., letcher, s.g., macía, m.j., makana, j.r., malizia, a., martínez‐ramos, m., mascaro, j., muthumperumal, c., muthuramkumar, s., nogueira, a., parren, m.p.e., parthasarathy, n., pérez‐salicrup, d.r., putz, f.e., romero‐saltos, h.g., sridhar reddy, m., sainge, m.n., thomas,d. and juliano van, m., 2015. biogeographical patterns of liana abundance and diversity. 131-146. ecology of lianas. john wiley and sons, new york, 131-146. dewalt, s.j., ickes, k., nilus, r., harms, k.e. and burslem, d.f.r.p., 2006. liana habitat associations and community structure in a bornean lowland tropical forest. plant ecology, 186:203-216. dewalt, s.j., schnitzer, s.a., chave, j., bongers, f., burnham, r.j., cai, z., chuyong, g., clark, d.b., ewango, c.e.n., gerwing, j.j., gortaire, e., hart, t., ibarra‐manríquez, g., ickes, k., kenfack, d., macía, m.j., remy makana, j., martínez‐ramos, m., mascaro, j., moses, s., muller‐ landau, h.c., parren, m.p.e., parthasarathy, n., pérez‐salicrup, d.r., putz, f.e., romero‐saltos, 18 h. and duncan thomas., 2010. annual rainfall and seasonality predict pan-tropical patterns of liana diversity and basal area. biotropica, 42:309-17. ewango, c.e.n., 2010. the liana assemblage of a congolian rain forest: diversity, structure and dynamics. ph.d. thesis. wageningen: wageningen university, 1-161. foster, j.r., townsend, p.a. and zganjar, c.e., 2008. spatial and temporal patterns of gap dominance by low-canopy lianas detected using eo-1 hyperion and landsat thematic mapper. remote sensing environ, 112:2104-2117. gamble, j.s. and fischer, c.e.c., 1915-1935. flora of the presidency of madras. vols. i-iii, adlard and co., london. gentry, a.h., 1991. the distribution and evolution of climbing plants. in: putz fe, mooney ha (eds) the biology of vines. cambridge university press, cambridge, 3-52. gollasimood, s., faridah-hanum, i., nazre, m. and abd kudus kamziah., 2012. abundance and distribution of climbers in a coastal hills forest in perak, malaysia. journal of agricultural science, 4:245-254. hegarty, e.e. and cabelle, g., 1991. distribution and abundance of vines in forest communities in: putz fe, mooney ha. (eds.). the biology of vines. cambridge university press, cambridge, 313-335. hooker, j.d., 1872-1897. the flora of british india. vol. i-vii. l. reeves and co. london. ibarra-manriquez, g. and martinez-ramos, m., 2002. landscape variation of liana communities in a neotropical rain forest. plant ecology, 160:91-112. ingwell, l.l., wright, s.j., becklund, k.k., hubbell, s. p. and schnitzer, s.a., 2010. the impact of lianas on 10 years of tree growth and mortality on barro colorado island, panama. journal of ecology, 98:879-887. jongkind, c.c.h. and hawthorne, w.d., 2005. a botanical synopsis of the lianes and other forest climbers; p. 19-39 in bongers, f., parren, m.p.e. and traore, d. (ed.), forest climbing plants of west africa diversity, ecology and management. cambridge. cabi publishing. karuppusamy, s. and ravichandran, v., 2016. diversity assessment of woody plants of megamalai wildlife sanctuary, theni district, tamil nadu. bio bulletin, 2:74-89. kuzee, m.e. and bongers, f., 2005. climber abundance, diversity and colonisation in degraded forests of different ages in côte d'ivoire: p. 67-84. in: bongers, f., parren, m.p.e. and traore, d. (eds.). forest climbers of west asia: diversity, ecology and management. cabi publishing. liu, w., meng, f.r., zhang, y., liu, y. and li, h., 2004. water input from fog drip in the tropical seasonal rain forest of xishuangbanna, south-west china. journal of tropical ecology, 20:517524. lu, x.t., tang, j.w., feng, z.l. and li, m.h., 2009. diversity and aboveground biomass of lianas in the tropical seasonal rain forests of xishuangbanna, sw china. revista de biología tropical. 57:211222 malhi, y. and wright, j., 2005. late twentieth-century patterns and trends in the climate of tropical forest regions. in: malhi y, phillips o (eds). tropical forests and global atmospheric change. oxford university press, oxford. mehta, v.k., sullivan, p.j., walter, m.t., krishnaswamy, j. and degloria, s.d., 2008. ecosystem impacts of disturbance in a dry tropical forest in southern india. ecohydrology, 1:149-160. mittermeier, r.a., myers, n. and gill, p.c., 2004. hotspots: earth’s richest and most endangered terrestrrial ecoregions. mexico city: cemex; sa, agrupación sierra madre, sc. mohandass, d., davidar, p., somasundaram, s., vijayan, l.a.l.i.t.h.a. and beng, k.c., 2015. influence of disturbance regime on liana species composition, density and basal area in the tropical montane evergreen forests (sholas) of the western ghats, india. tropical ecology, 56:169-182. pandian and ravichandran /journal of tropical forestry and environment vol. 9, no. 02 (2019) 12-20 19 mohandass, d. and davidar, p., 2010. the relationship between area, and vegetation structure and diversity in montane forest (shola) patches in southern india. plant ecology and diversity, 3:6776. muthuramkumar, s., ayyappan, n., parthasarathy, n., mudappa, d., raman, t.s., selwyn, m.a. and pragasan, l. a., 2006. plant community structure in tropical rain forest fragments of the western ghats india. biotropica, 38:143-60. muthumperumal, c. and parthasarathy, n., 2009. angiosperms, climbing plants in tropical forests of southern eastern ghats, tamil nadu, india. check list. 5:092-111. muthumperumal, c. and parthasarathy, n., 2010. a large-scale inventory of liana diversity in tropical forests of south eastern ghats, india. systematics and biodiversity, 8:289-300. muthumperumal, c and parthasarathy, n. 2013. diversity, distribution and resource values of woody climbers in tropical forests of southern eastern ghats, india. journal of forestry research, 24:365374. nair, k.k.n. and nayar, m.p., 1986. flora of courtallam, botanical survey of india. 441 nair, n.c. and daniel, p., 1986. floristic diversity of the western ghats and its conservation: a review. proceedings. animal sciences-indian academy of sciences. nayar, m.p. and sastry, a.r.k., 1987. red data book of indian plants. bsi calcutta, 1. nayar, m.p. and sastry, a.r.k., 1990. red data book of indian plants, botanical survey of india, culcutta, camp. in camp workshop, shimla, 3. nayer, m.p. and sastry, a.r.k., 1988. red data book of indian plants, vol. ii. botanical survey of india. pandian, e. and parthasarathy, n., 2016. decadal (2003-2013) changes in liana diversity, abundance and aboveground biomass in four inland tropical dry evergreen forest sites of peninsular india journal of forestry research, 27:133-146. parkinson, c.e., 1923. a forest flora of the andaman islands, govt. of india press. parthasarathy, n., muthuramkumar, s. and reddy, m.s., 2004. patterns of liana diversity in tropical evergreen forests of peninsular india. forest ecology and management, 190:15-31 phillips, o., 1991. the ethnobotany and economic botany of tropical vines. in: putz, f.e., mooney, h.a., editors. the biology of vines. cambridge: cambridge university press, 427-475. phillips, o.l., martínez, r.v., arroyo, l., baker, t.r., killeen, t., lewis, s.l., malhi, y., mendoza, a.m., neill, d., vargas, p.n., alexiades, m., ceron, c., fiore, a.d., erwin, t., jardim, a., placios, w., saldias, m. and vinceti, b., 2002. increasing dominance of large lianas in amazonian forests. nature, 418:770. poulsen, a.d., hafashimana, d., eilu, g., liengola, i.b., ewango, c.e.n. and hart, t.b., 2005. composition and species richness of forest plants along the albertine rift, africa. biologiske skrifter. 55:129-43. putz, f.e. and mooney, h.a., 1991. the biology of vines. cambridge university press. putz, f.e., 1984. the natural history of lianas on barro colorado island panama. ecology, 65:1713-1724. reddy, m.s. and parthasarathy, n., 2006. liana diversity and distribution on host trees in four inland tropical dry evergreen forests of peninsular india. tropical ecology, 47:109-124. refuge, e.b., forest, a. and post, d., 2016. floristic species composition and structure of a mid-elevation tropical montane evergreen forests (sholas) of the western ghats, southern india. tropical ecology. 57:533-543. sarvalingam, a., rajendran, a. and aravindhan, v., 2011. curative climbers of maruthamalai hills in the southern western ghats of tamil nadu, india. international journal of medicinal and aromatic plants, 1:326-332. sarvalingam, a. and rajendran, a., 2012. diversity of liana species in maruthamalai hills of southern western ghats, india. phytotaxonomy. 12:131-135. 20 sarvalingam a, rajendran a., 2016. rare, endangered and threatened (ret) climbers of southern western ghats, india. revista chilena de historia natural, 89:9. schnitzer, s.a. and bongers, f., 2002. the ecology of lianas and their role in forests. trends in ecology and evolution, 17:223-230. schnitzer, s.a. and bongers, f., 2011. increasing liana abundance and biomass in tropical forests: emerging patterns and putative mechanisms. ecology letters, 14:397-406. schnitzer, s.a., dewalt, s.j. and chave, j., 2006. censusing and measuring lianas: a quantitative comparison of the common methods1. biotropica, 38:581-591. schnitzer, s.a., kuzee, m.e. and bongers, f., 2005. disentangling aboveand below-ground competition between lianas and trees in a tropical forest. journal of ecology, 93:1115-1125. schnitzer, s.a., mangan, s.a., dalling, j.w., baldeck, c. a., hubbell, s.p., ledo, a., muller-landau, h., tobin, m.f., aguilar, s., brassfield, d., hernandez, a., lao, s., perez, r,. valdes, o. and yorke, s.r., 2012. liana abundance, diversity, and distribution on barro colorado island, panama. plos one. 7: e52114. walter, k.s. and gillet, h.j., 1998. iucn red list of threatened plants. compiled by the world conservation monitoring centre. iucn-the world conservation union, gland, switzerland and cambridge, uk. 862. seger, g.d.d.s. and hartz, s.m., 2014. checklist of climbing plants in an araucaria forest of rio grande do sul state, brazil. biota neotropica, 14. sukumaran, s. and raj, a.d.s., 2007. rare, endemic, threatened (ret) trees and lianas in the sacred groves of kanyakumari district. indian forester, 133:1254-1266. swaine, m.d. and grace, j., 2007. lianas may be favoured by low rainfall: evidence from ghana. plant ecology. 192:271-276. tielborger, k., bilton, m.c., metz, j., kigel, j., holzapfel, c., lebrija-trejos, e., konsens, i., parag, h.a. and sternberg, m., 2014. middle-eastern plant communities tolerate 9 years of drought in a multisite climate manipulation experiment. nature communication, 5:5102. toledo, m., 2010. neotropical lowland forests along environmental gradients. ph.d. thesis, wageningen university. trigas, p., panitsa, m. and tsiftsis, s., 2013. elevational gradient of vascular plant species richness and endemism in crete-the effect of post-isolation mountain uplift on a continental island system. plos one. 8:e59425. uma, r. and parthipan b., 2015. survey on medico-botanical climbers in pazhayaru river bank of kanyakumari district, tamilnadu. journal of medicinal plants studies, 3:33-6. vivek, p. and parthasarathy, n., 2014. liana community and functional trait analysis in tropical dry evergreen forest of india. journal of plant ecology, 8:501-512. wright, s.j., calderon, o., hernandez, a. and paton, s., 2004. are lianas increasing in importance in tropical forests? a 17-year record from panama. ecology, 85:484-489. yang, s.z., fan, h., li, k.w. and ko, t.y., 2018. how the diversity, abundance, size and climbing mechanisms of woody lianas are related to biotic and abiotic factors in a subtro pical secondary forest, taiwan. folia geobotanica, 1-12. yorke, s.r., schnitzer, s.a., mascaro, j., letcher, s.g. and carson, w.p., 2013. increasing liana abundance and basal area in a tropical forest: the contribution of long‐distance clonal colonization. biotropica, 45:317-324. 48 genetic variability assessment of sorghum (sorghum bicolor (l.) moench) germplasm accessions using qualitative morphological descriptors kaluthanthri d.v.s., dasanayaka p.n.* department of botany, faculty of applied sciences, university of sri jayewardenepura, nugegoda, sri lanka date received: 14-12-2018 date accepted: 01-05-2019 abstract sorghum (sorghum bicolor (l.) moench) is considered as the fifth most important cereal crop in the world. it is well adapted to a range of environmental conditions. this study was based on twenty six sorghum germplasm accessions conserved at the seed gene bank of plant genetic resource center, gannoruwa, sri lanka. the evaluation of the morphological diversity was based on 14 qualitative morphological traits outlined by the international plant genetic resources institute. qualitative data recorded from morphological traits were analyzed using proc cluster procedure of sas software. the clustering pattern of studied sorghum accessions based on qualitative morphological markers comprised of seven major clusters. clustering pattern based on the qualitative traits depicts the geographical origin of the studied accessions. this can be explained by the fact that qualitative traits are less influenced by the environment. in principle, qualitative data are expected to provide additional information on hierarchical units. observation of a considerably high number of clusters consolidates that principle. there were 13 polymorphic qualitative morphological traits with respect to all the studied sorghum germplasm accessions. cluster i, ii, iii, iv, v and vi had one or several features shared by all the member accessions those cannot be found in all the members of any other clusters. also there were unique features restricted to cluster ii, iii, v and vi. this study reveals sufficient genetic relatedness of studied sorghum germplasm accessions which will meaningful in the conservation and breeding programs of the crops. keywords: sorghum bicolor, germplasm accessions, morphological diversity, qualitative traits 1. introduction sorghum (sorghum bicolor (l.) moench) is a monocotyledon, self-pollinating plant, belonging to the family of poaceae is considered as the fifth most important cereal crop in the world after wheat (triticum aestivum), rice (oryza sativa), maize (zea mays) and barley (hordeum vulgare) in terms of production and area planted. sorghum is consumed into a wide variety of foods, such as baked products, tortillas, couscous, gruel, steam-cooked products, semi-leavened breads, popped form, fermented or nonfermented porridges and alcoholic or non-alcoholic beverages (anglani, 1998). relatively high tolerance to drought and heat makes this crop an ideal crop for human and animal consumption especially in areas with extremely unfavourable temperature and in dry regions receiving minimum precipitation (ratnavathi et al., 2012). therefore, sorghum is particularly important to food security in the arid and semi-arid regions of the world. furthermore, consumption of sorghum products can be recommended for patients suffering *correspondence: nilanthiedas@sjp.ac.lk tel: +94 718122358 issn 2235-9370 print/issn 2235-9362 online ©2019 university of sri jayewardenepura doi: https://doi.org/10.31357/jtfe.v9i1.3950 https://doi.org/10.31357/jtfe.v9i1.3950 kaluthanthri and dasanayaka /journal of tropical forestry and environment vol. 9, no. 01 (2019) 48-58 49 from celiac disease or diabetes (park et al. 2012; taylor et al., 2006). nevertheless, being the only known natural food source of the 3-deoxyanthoxyanins (3-dxa) in significant quantities, sorghum may be useful in helping reduce incidence of gastrointestinal cancer (yang et al., 2009). germplasm is the basic material utilized in assessing genetic variability. as defined by upadhyaya et al. (2010), the total gene pool of a species including landraces, advanced breeding lines, popular cultivars, wild and weedy relatives can be considered as a ‘germplasm’. apparently, development of well adapted novel crop varieties with promising high yields through breeding strategies can be recognized as one of the most successful agricultural strategies employed over the past century, particularly with regards to the ‘green revolution’ (gleadow et al., 2013). development of such new crop varieties with high yield and desired traits depends on the availability of plant genetic resources with sufficient information. identification of crop plants that exhibit exploitable variation for the trait or traits of interest is the first step of any meaningful breeding program. conservation of plant genetic material using in-situ and ex-situ conservation strategies play a vital role in breeding programs as well (shehzad et al., 2014). sorghum is believed to have a wide range of genetically diverse germplasm (prajapati et al., 2018). sorghum is a diploid (2n=20), self-pollinated crop but capable of out crossing in various frequencies. wind and insects such as honeybees, wild bees and beetles contribute to the out crossing yet the rate of out crossing is in the range of less than 10% to 73% (barnaud et al., 2008). genetic diversity in plants is affected by several factors such as selection, mutation, migration and genetic drift. in fact, domestication or artificial selection favours few alleles over the others resulting in increased frequency of selected alleles (bhandari et al., 2017). therefore, plant genetic materials with wide and diverse origins and genetic backgrounds are known to have a genetic diversity. genetic diversity study is a staggering breakthrough in understanding intra-specific crop performance which will ultimately guide to crop improvement (aremu, 2005). moreover it is a step wise process which is performed using specific statistical method or combination of methods through existing variations in the nature with respect to particular crop (weir, 1996; warburton and crossa 2000; christini et al., 2009). assessment of genetic diversity can be accomplished through the use of various data such as morphological and agronomic, pedigree, biochemical and molecular data. morphological traits are genetically controlled by number of genes and their expression depends on environmental factors in most cases. there are both quantitative and qualitative morphological traits those play vital roles in classification of individuals. qualitative morphological traits are subjected to comparatively less environmental influence and have mono or oligogenic genetic control (lima et al., 2017). they do not have quantitative values and might be binary or multicategory. utilisation of qualitative morphological data is a fruitful strategy in genetic diversity studies not only because it is a practical, low-cost application, with no sophisticated equipment requirements but also they are expected to provide additional information on hierarchical units. there are number of sorghum germplasm accessions conserved at plant genetic resource center (pgrc), gannoruwa, sri lanka. having a better knowledge about the genetic diversity of those germplasm accessions will help in enhancement of breeding and germplasm conservation of this crop. assessing the genetic diversity of ex-situ conserved sorghum germplasm accessions using qualitative morphological markers is the main objective of this study as the morphological characterization is an important measure of assessing genetic diversity in crop plants. according to meijaard et al. (2013), knowing more about local people usage of forests (such as fuel, medicine, food and food additives, building construction, etc) is an extremely important factor that could enhance planning of land use and minimise the conflict with them. 50 2. methodology 2.1 plant material and data observation a total of twenty-six sorghum (sorghum bicolor) accessions including sixteen local, six italian, two french and two foreign accessions with unknown origins obtained from active seed gene bank of pgrc, gannoruwa, sri lanka (table 1) was evaluated with regard to morphological descriptors outlined by the international plant genetic resources institute (ipgri). this study was based on the evaluation of these germplasm accessions using qualitative traits. plant colour, synchrony of flowering, grain lustre and grain form were the studied binary traits whereas leaf midrib colour, waxy bloom, inflorescence compactness and shape, inflorescence exsertion, lodging susceptibility, senescence, shattering, glume colour, grain covering and grain colour were counted as multicategorical traits with more than two possible levels. table 1: details of the studied sorghum germplasm accessions. accession no. accession name origin 93 edal eringu monaragala 104 poth iringu monaragala 110 karal iringu monaragala 111 rathu thiringu monaragala 112 sudu thiringu monaragala 207 idal iringu monaragala 285 edal eringu matale 310 sorghum matale 403 edal eringu kurunegala 421 edal eringu kurunegala 774 karal iringu matale 971 karal iringu hambantota 1531 sorghum anuradhapura 1546 edal eringu nuwara eliya 1701 sorghum sri lanka 1824 edal eringu kandy 5364 unknown 5365 unknown 6004 arval france 6005 argence france 6006 roce italy 6007 soave italy 6008 vespa italy 6010 mn 150 italy 6012 soave italy 6013 wonder dwarf italy 2.2 experimental site and design the study was carried out in a plant house at the department of botany, faculty of applied sciences, university of sri jayewardenepura, nugegoda, sri lanka. the experiment was arranged in a randomised complete block design (rcbd) with five replications as two individuals from each accession per block. seeds of each sorghum accession were sown in small plastic pots filled with normal kaluthanthri and dasanayaka /journal of tropical forestry and environment vol. 9, no. 01 (2019) 48-58 51 soil. pots were maintained in the plant house for germination. twenty five day-old seedlings were transplanted separately in to the large plastic pots filled with mixture of soil, sand and compost (1:1:1) as each pot contained two plants. all weeds were controlled removing manually. 2.3 statistical analysis qualitative data recorded from morphological traits were analysed using proc cluster procedure of sas software (sas institute, 2011) by following ward minimum variance clustering method (ward, 1963) with the gower distance matrix (gower, 1971). 3. results according to the pseudo-f and pseudo-t2 criteria obtained from the cluster analysis based on qualitative data, the optimal number of clusters required to represent the genetic diversity among the studied sorghum germplasm accessions was seven (figure 1). figure 1: distribution of pseudo-f and pseudo-t2 statistics according to the number of clusters. figure 2: phenetic dendrogram of 26 sorghum accessions obtained through the algorithm of gower in the evaluation of 13 qualitative morphological traits 52 the phenetic dendrogram of dissimilarity obtained through the algorithm of gower (gower, 1971) in the evaluation of 13 qualitative morphological traits is represented in figure 2. the dendrogram shows that seven clusters were formed at dissimilarity co-efficient of 0.06. the number of accessions per cluster ranged from two in ‘cluster i’ to six in ‘cluster v’. ‘cluster i’ comprised of two foreign accessions (5364 and 5365) with unknown origins. there were five sri lankan accessions (285, 403, 421, 774 and 971) grouped into ‘cluster ii’. three italian (6006, 6007 and 6010) and two french accessions (6004 and 6005) were clustered in ‘cluster iii’ while the remaining three italian accessions (6008, 6012 and 6013) were grouped into ‘cluster iv’. sri lankan accessions (104, 110, 111, 112, 207 and 1824) coming from monaragala and kandy districts made the ‘cluster v’. ‘cluster vi’ and ‘cluster vii’ comprised of two (1531 and 1701) and three (93, 310 and 1546) sri lankan accessions respectively. out of 14 studied qualitative morphological traits, one trait namely grain form was recorded as a monomorphic marker with respect to all the studied sorghum germplasm accessions whereas the rest of traits were polymorphic. there are two states of grain form as single and twin. but grains from each and every accession were recorded as single form. distribution of the states of polymorphic qualitative morphological traits among studied sorghum germplasm accessions and observed clusters of the dissimilarity dendrogram is summarised in table 2. two different colours were observed for leaf midrib as dull green and white. majority of accessions had white midribs whereas only seven accessions belonging to cluster i, ii and iii were observed to have dull green midribs. stems of all the studied accessions were covered with the waxy bloom and majority of them were mostly bloomy. apparently one italian accession (6006) was observed with completely bloomy stems. when the compactness and shape of the inflorescence were considered at the same time, there were six types of inflorescences as very loose erect, semi-loose erect, loose erect, loose drooping, compact elliptic and semi-compact elliptic. compact elliptic inflorescences were observed in majority of accessions. loose drooping and semi-compact elliptic type could be observed only in two sri lankan accessions from monaragala (207) and matale (310) districts respectively. slightly exserted, exserted and well-exserted inflorescences were recorded. wellexserted inflorescences were observed in majority of accessions. pigmented plant was the most frequent plant colour and was observed in 19 accessions. majority of studied sorghum accessions showed low level of lodging whereas two sri lankan accessions (104 and 1824) were observed to be highly lodged. senescence could be observed in each and every plant. italian and french accessions showed comparatively low level of senescence. synchrony of flowering was absent in lot of accessions. one sri lankan accession (1531) from anuradhapura district and four exotic accessions (5364, 5365, 6008 and 6013) were observed with synchronised flowering patterns. low level of shattering was the most frequent nature of shattering. one french (6004) and four italian (6007 6008, 6010 and 6013) accessions were observed with highly shattered panicles. four different colours of glumes as black, mahogany, red and sienna were observed. grains of all accession were covered by glumes and different extents of covering were observed. surprisingly, grains of all the accessions (104, 110, 111, 112, 207 and 1824) from cluster v were fully covered by the glumes. majority of accessions had brown colour grains whereas two sri lankan accessions (285 and 403) had white colour grains. red and yellow colour grains were also observed. only two sri lankan accessions (1531 and 1701) had lustrous grains. cluster i, ii, iii, iv, v and vi had one or several features shared by all the member accessions those cannot be found in all the members of any other clusters. all the accessions from ‘cluster i’ were tan plants and showed intermediate level of senescence with synchronized flowering patterns. furthermore, well-exserted inflorescences of those plants bore yellow colour grains. ‘cluster ii’ members had black glumes. midribs of slightly senescence plants from ‘cluster iii’ members were dull green. ‘cluster iv’ members had 75% covered grains bearing from slightly exserted inflorescences whereas member accessions of ‘cluster v’ observed to have fully covered grains. lustrous red colour grains bearing from very loose erect primary branches of ‘cluster vi’ member accessions were covered with red colour longer glumes. kaluthanthri and dasanayaka /journal of tropical forestry and environment vol. 9, no. 01 (2019) 48-58 53 also there were unique features restricted to particular clusters. white grains (285 and 403) were observed only in ‘cluster ii’. plants those completely covered with waxy bloom (6006) and highly shattered inflorescences (6004 and 6007) could be found only in ‘cluster iii’. highly lodged plants (104 and 1824), loose drooping panicles (207) and fully covered grains (104, 110, 111, 112, 207 and 1824) could be found only in ‘cluster v’. only ‘cluster vi’ members had semi compact elliptic panicles (310) and lustrous grains (1531 and 1701). table 2: distribution of the states of polymorphic qualitative morphological traits among studied sorghum germplasm accessions and observed clusters of the dissimilarity dendrogram. qualitative traits states of the trait recorded accessions with the state observed clusters with the state 1. leaf midrib colour dull green 403, 5364, 6004, 6005, 6006, 6007, 6010 i, ii, iii white 93, 104, 110, 111, 112, 207, 285, 310, 421, 774, 971, 1531, 1546, 1701, 1824, 5365, 6008, 6012, 6013 i, ii, iv, v, vi, vii 2. waxy bloom slightly 1531, 1546, 1824 v, vi, vii medium 285, 310, 421, 971, 6004, 6005, 6007, 6010 ii, iii, vii mostly 93, 104, 110, 111, 112, 207, 403, 774, 1701, 5364, 5365, 6008, 6012, 6013 i, ii, iv, v, vi, vii completely 6006 iii 3. inflorescence very loose erect 1531, 1701, 6004 iii, vi compactness and semi-loose erect 111, 1824, 6010, 6012, 6013 iii, iv,v shape loose erect 93, 104, 110, 1546, 6005, 6007 iii, v, vii loose drooping 207 v compact elliptic 112, 285, 403, 421, 774, 971, 5364, 5365, 6006, 6008 i, ii, iii, iv, v semi-compact elliptic 310 vi 4. inflorescence slightly exserted 112, 774, 1824, 6006, 6008, 6012, 6013 ii, iii, iv, v exsertion exserted 104, 111, 207, 310, 1546, 1701, 6007 iii, v, vi, vii well-exserted 93, 110, 285, 403, 421, 971, 1531, 5364, 5365, 6004, 6005, 6010 i, ii, iii, v, vi, vii 5. plant colour pigmented 93, 104, 111, 207, 285, 310, 403, 774, 971, 1531, 1546, 1701, 6004, 6005, 6006, 6007, 6008, 6010, 6012 ii, iii, iv, v, vi, vii tan 110, 112, 421, 1824, 5364, 5365, 6013 i, ii, iv, v 6. lodging susceptability low 93, 110, 111, 112, 207, 310, 403, 421, 1531, 1546, 5364, 5365, 6004, 6005, 6006, 6007, 6008, 6010, 6012, 6013 i, ii, iii, iv, v, vi, vii intermediate 285, 774, 971, 1701 ii, vi high 104, 1824 v 54 qualitative traits states of the trait recorded accessions with the state observed clusters with the state 7. senescence very slightly 207, 6004, 6005, 6006, 6007, 6010 iii, v slightly 112, 421, 6013 ii, iv, v intermediate 110, 971, 5364, 5365, 6008, 6012 i, ii, iiii, vii mostly 93, 104, 111, 285, 310, 403, 774, 1531, 1546, 1701, 1824 ii, v, vi, vii 8. synchrony of flowering absent 93, 104, 110, 111, 112, 207, 285, 310, 403, 421, 774, 971, 1546, 1701, 1824, 6004, 6005, 6006, 6007, 6010, 6012 ii, iii, iv, v, vi, vii present 1531, 5364, 5365, 6008, 6013 i, iv, vi 9. shattering low 93, 104, 110, 111, 112, 207, 285, 310, 774, 1531, 1546, 1701, 1824, 5365, 6005, 6006 i, ii, iii, v, vi, vii intermediate 403, 421, 971, 5364, 6012 i, ii, iv high 6004, 6007 iii very high 6008, 6010, 6013 iii, iv 10. glume colour black 285, 403, 421, 774, 971, 6012 ii, iv mahogany 310, 1546, 6006, 6007, 6008, 6010, 6013 iii, iv, vii red 93, 1531, 1701 vi, vii sienna 104, 110, 111, 112, , 207, 1824, 5364, 5365, 6004, 6005 i, iii, v 11. grain covering 50% covered 93, 285, 403, 421, 5364 i, ii, vii 75% covered 310, 774, 971, 1546, 5365, 6007, 6008, 6010, 6012, 6013 i, ii, iii, iv, vii fully covered 104, 110, 111, 112, 207, 1824 v longer glumes 1531, 1701, 6004, 6005, 6006 iii, vi 12. grain colour brown 104, 110, 111, 112, 207, 1546, 1824, 6004, 6005, 6006, 6007, 6008, 6010, 6012, 6013 iii, iv, v, vii red 93, 310, 1531, 1701 vi, vii white 285, 403 ii yellow 421, 774, 971, 5364, 5365 i, ii 13. grain lustre present 1531, 1701 vi absent 93, 104, 110, 111, 112, 207, 285, 310, 403, 421, 774, 971, 1546, 1824, 5364, 5365, 6004, 6005, 6006, 6007, 6008, 6010, 6012, 6013 i, ii, iii, iv, v, vii 4. discussion consideration of pseudo statistic including pseudo-f and pseudo-t2 values is one of the best ways for judging the optimal number of clusters in a data set. relatively large values of pseudo-f compared to nearby values indicate statistically significant clustering points. the general rule for identifying the best clustering point which is statically significant with regard to values of the pseudo-t2statistic is to move along the line starting from the end corresponding to the highest number of clusters until find the first value markedly larger than the previous value and move back along the line by one cluster. when these two statistics, pseudo-f and pseudo-t2 were taken into consideration, the studied 26 sorghum germplasm accessions can be divided into statistically significant seven clusters based on 13 qualitative morphological traits (sas institute inc, 2011). kaluthanthri and dasanayaka /journal of tropical forestry and environment vol. 9, no. 01 (2019) 48-58 55 sri lankan accessions were observed in ‘cluster ii’, ‘cluster v’, ‘cluster vi’ and ‘cluster vii’. apparently ‘cluster i’ and ‘cluster ii’ separated from the rest of clusters at somewhere around the dissimilarity co-efficient of 0.25. surprisingly, sri lankan accessions coming from three different districts as hambantota, kurunegala and matale made the ‘cluster ii’. clustering pattern based on the qualitative traits depicts the geographical origin of the studied accessions. this can be explained by the fact that qualitative traits are less influenced by the environment. in principle, qualitative data are expected to provide additional information on hierarchical units. observation of a considerably high number of clusters consolidates that principle. leaf midrib colour is an important morphological trait as it is used by farmers to distinguish between juicy and non-juicy types of sorghum landraces (teshome et al., 1997). as reported by rangaswami (1936), green colour midribs are associated with juicy stems while white midribs are associated with pithy stems. according to doggett (1988) white or yellow colour midribs can be found in dry pithy varieties whereas sweet juicy types tend to have an opaque green midrib often with the fine white line down the centre. mutants with brown midribs have also been reported. ayyangar and nambiar (1941b) proved that the dark green midrib is dominant to lighter shades of green. in this study, ‘cluster iii’ members from italy and france had dull green midribs. waxy bloom can be observed in every plant of sorghum in different amounts. genotypic expression of wax is controlled by a family of genes. the phenotypic expressions of these genes are enhanced by plant age and water status. presence of wax plays an important role in preventing plants from water loss by reducing the solar energy load on t he plant surface through reflectance and reduction the solar energy load on the leaf surface (hamissou and weibel, 2004). one italian accession (6006) from this study found to be completely covered with wax. the inflorescence of a sorghum plant is a panicle with a central rachis which originates from primary branches. the shape and compactness of the panicle varies from accession to accession. in here, the variation in rachis length, branch length, distance apart of the whorls and angle of branching give rise to a large number of panicle forms in the face of shape and compactness. ayyangar (1939) reported that loose panicle is dominant to compact panicle. while semi compact panicle is dominant to compact panicle. usually each panicle contains between 800 and 3000 seeds depending on the genetic background and environmental influence. the immature inflorescence is bloomed through the top leaf sheath after the uppermost leaf has expanded. the mature inflorescence may remain with lower part still surrounded by the uppermost leaf sheath as slightly exserted manner, or it may be carried well clear of the top leaf sheath as well exserted inflorescence (doggett, 1988). majority of accessions observed in the current study was compact elliptic and well exserted. sorghum plants can be either pigmented or tan in colour. the glumes and sheath of red plants were found to accumulate 3-deoxyanthocyanidins which is the major pigments that can be found in sorghum whereas the glumes and sheath of tan plants accumulated apigenin (siame et al., 1993). growth of the stem of sorghum plants is usually erect, but in some varieties the stem bending until it may be almost parallel to the ground at flowering time. in this study, two sri lankan accessions (104 and 1824) were observed to be highly lodged. when the panicle is filled with grains, the stem tends to touch the ground. according to deggett (1988), one to three concentric root band rings containing primordial can be found immediately above the attachment of leaf sheath at each stem node of sorghum. therefore, when a plant falls over, roots may develop at the nodes in contact with the ground, and advantage can be taken of this fact to grow sorghums from cuttings. 56 as described by downes (1968) even though sorghum is an annual crop, non senescent types can be survived for years through generation of tillers from old plant bases. even though each and every studied sorghum plants showed some level of senescence, few accessions were slightly senescence. as suppression of grain shattering is a valuable agronomic trait acquired through the domestication of sorghum, majority of studied accessions had comparatively low level of shattering. according to quinby and martin (1954), glume colour is affected by the same gene which is responsible for plant colour and several other genes as well. the effects of these genes produce a range of glume colours from straw to blackish purple, reddish purple, golden, mahogany and sienna. according to the results coming from this study, all the grains covered with red colour glumes came from pigmented plants. usually almost all grains of sorghum are covered by a glume in different extents. in this study, all the fully covered grains had sienna colour glumes. in most cases, the glume can open by itself and expose the grain. however cleistogamy was observed in several varieties of sorghum (ayyangar and ponnaiya, 1939e) due to the rolling of the inner glume, so that it claps the internal flower structures and thereby normal opening of the glumes can be prevented (merwine et al, 1981). according to ayyangar and krishnaswamy (1941), grain colour varies from the pale yellow through various shades of red and brown to deep purple brown. the pigment that responsible for the grain colour is confined to the seed coat layer with the exception of yellow, which can be present in the endosperm. in here, majority of seeds were brown in colour. lustrous grains conquer consumer preference over non-lustrous grains. according to the study carried out by audilakshmi and aruna (2005), for the develoment of a hybrid which will produce lustrous grains, both parents need to be lustrous and homozygous for the alleles conferring grain lustre at a common locus. in fact, there were two sri lankan accessions (1531 and 1701) with lustrous grains. 5. conclusion gower distance matrix obtained by following ward minimum variance clustering method is a suitable method for classifying sorghum germplasm accessions with respect to qualitative morphological traits. this study reveals sufficient genetic relatedness of studied sorghum germplasm accessions which will meaningful in the conservation and breeding programs of the crops. acknowledgment the authors would like to acknowledge the university research council, university of sri jayewardenepura for the financial assistance (research grant no: asp/1/re/sci/2017/07) and plant genetic resource center (pgrc), gannoruwa, sri lanka. references anglani, c., 1998. sorghum for human food-a review. pl. foods human nutrients, 52:85-95. aremu, c.o., 2005. diversity selection and genotypes environment interaction in cowpea. ph.d thesis. university of agriculture, abeokuta, nigeria, 210. audilakshmi, s. and aruna, c., 2005. genetic analysis of physical grain quality characters in sorghum. the journal of agricultural science. 143:267-273. ayyangar, g.n.r., 1939. studies in sorghum. journal of madras university, 11:131. ayyangar, g.n.r. and krishnaswami, n., 1941. studies on the histology and colouration of the pericarp of the sorghum grain. proceedings of the indian academy sciences, b14:114. ayyangar, g.n.r. and nambiar, a.k., 1941b. inheritance of depth of green colour in the leaves of sorghum. current sciences, 10: 492. https://www.cambridge.org/core/search?filters%5bauthorterms%5d=s.%20audilakshmi&eventcode=se-au https://www.cambridge.org/core/search?filters%5bauthorterms%5d=c.%20aruna&eventcode=se-au https://www.cambridge.org/core/search?filters%5bauthorterms%5d=s.%20audilakshmi&eventcode=se-au https://www.cambridge.org/core/search?filters%5bauthorterms%5d=c.%20aruna&eventcode=se-au kaluthanthri and dasanayaka /journal of tropical forestry and environment vol. 9, no. 01 (2019) 48-58 57 ayyangar, g.n.r. and ponnaiya, b.w.x., 1939e. cleistogamy and its inheritance in sorghum, current sciences, 10:410. barnaud, a, trigueros, g, mckey, d., joly, h., 2008. high outcrossing rates in fields with mixed sorghum landraces: how are landraces maintained?. heredity, 101:445-452. bhandari, h.r., bhanu, a.n., srivastava, k., singh, m.n., shreya and hemantaranjan, a., 2017. assessment of genetic diversity in crop plants-an overview. advances in plants and agriculture research, 7:255. christine, joshua, h., william, a. and stacy, a. 2009. genetic diversity of creeping bentgrass cultivars using ssr markers. international turfgrass society research journal, 11. doggett, h., 1988. sorghum, second ed. longmans scientific and technical, uk. downes, r.w., 1968. the effect of temperature on tillering of grain sorghum seedlings. australian journal of agricultural research, 19:59. gleadow, r., johnson, a. and tausz, m., 2013. crops for a future climate. functional plant biology. 40: iii-vi. gower j c., 1971. a general coefficients of similarity and some of its properties. biometrics, 27: 857-874. hamissou, m. and weibel, d.e., 2004. the effects of epicuticular wax cover on the rate of water loss of sorghum bicolor (l.) moench. asian journal of plant sciences, 3:742-746. lima, m.n.r., abilio de queiroz, m., flor da silva oliveira, a.e., neto, i.s.l. and simao de oliveira, r., 2017. integration of quantitative and qualitative descriptors for genetic diversity studies of watermelon accessions. australian journal of crop science, 11:1005-1015. merwine, n.c., goerley, l.m. and blackwell, k.h., 1981. inheritance of papery glumes and cleistogamy in sorghum. crop science, 21:953. park, j.g, lee, s.h, chung, i.m, park, y., 2012. sorghum extract exerts an anti-diabetic effect by improving insulin sensitivity via ppar-γ in mice fed a high-fat diet. nutrition research and practice, 6:322-327. prajapati, d.r., pahuja, s.k., verma, n.k. and chaudhary, s., 2018. morphological characterization of sorghum [sorghum bicolor (l.) moench] germplasm for dus traits. international journal of current microbiology applied sciences, 7:2058-2071. quinby, j.r. and martin, j.h., 1954. sorghum improvement. advances in agronomy, 6:305. rangaswami, g., ayyangar, n., sankara, m.a., ayyar and panduranga rao, v., 1936. linkage between purple leaf sheath colour and juiciness of stalk in sorghum. plant sciences, 5:1-3. ratnavathi, c.v., sivanuri, k.r., kumar, s.b.v., krishna, d.g. and patil, j.v., 2012. effect of time of planting on cane yield and quality characters in sweet sorghum. journal of sustainable bioenergy systems, 2:1-9. sas institute inc., 2011. sas® 9.3 system options: reference. 2nd ed. sas institute inc., cary. shehzad, t. and okuno, k., 2014. diversity assessment of sorghum germplasm and its utilization in genetic analysis of quantitative traits-a review. australian journal of crop science, 8:937-944. siame, b.a., ejeta, g. and butler, l.g., 1993. role of pigments and tannins in the reaction of tan and red near-isogenic sorghum check for this species in other resources lines to leaf disease. african crop science journal, 1. taylor, j.r.n, schoberb, t.j. and beanb s.r., 2006. novel food and non-food uses for sorghum and millets. journal of cereal science, 44:252-271. teshome, a., baum, b.r., farig, l., torrance, j.k., arnason, t.j. and lambert, j.d., 1997. sorghum (sorghum bicolour (l.) moench) landrace variation and classification in north shewa and south welo, ethiopia. eup. upadhyaya, h.d., yadav, d., dronavalli, n., gowda, c.l.l., and singh, s., 2010. mini core germplasm collections for infusing genetic diversity in plant breeding programs. electronic journal of plant breeding, 1:1294-130. 58 warburton, m. and crossa, j., 2000. data analysis in the cimmyt. applied biotechnology. center for fingerprinting and genetic diversity studies. cimmyt, mexico. ward, j.h., 1963. hierarchical grouping to optimize an objective function. journal of american statistical association 58:236-244. weir, b.s., 1996. intraspecific differentiation, 385-403. in d.m. hillis et al. (ed). molecular systematics 2nd edition sunderlands m.a. yang, l., browning, j.d. and awika, j.m., 2009. sorghum 3-deoxyanthocyanins possess strong phase ii enzyme. musau and mugo /journal of tropical forestry and environment vol. 9, no. 01 (2019) 89-100 89 influences of human activities on tree density and diameter distribution in museve and mutuluni dryland forest fragments; kitui county, kenya musau j.m.*, mugo j.m. department of natural resources, karatina university, karatina, kenya date received: 21-10-2018 date accepted: 14-05-2019 abstract forest fragments in arid and semi-arid lands are key water catchment areas and provide important ecosystem services. however, uncontrolled human activities are fast altering their stem density basal area and diameter structure resulting into forest degradation. besides, information regarding tree density and diameter size-class distribution of dryland forest fragments such as museve and mutuluni is lacking. thus, the purpose of this study was to document key human activities in museve and mutuluni forest fragments in kitui, kenya and comparatively investigate their influences on stem density, basal area and stem diameter size-class distribution. two belt transect of 20 m wide and 500 m long, with contiguous sample plots of 20 m by 20 m and subplots of 10 m by 10 m were established in each forest. evidence of human activities, abundances and diameter measurements for mature trees were assessed in the 20 m by 20 m plots while abundances and diameter measurements for saplings were in the subplots. mann-whitney, t-test and logistic regression were used for data analysis. mutuluni forest exhibited significantly (p<0.05) high stem density compared to museve however, basal area density was not different (p<0.05). introduction of exotic species enhanced basal area and stem density (p<0.05) in museve forest. tree cutting reduced both basal area and stem density in museve forest and only stem density in mutuluni. stem-density diameter distribution in both forests followed a reverse j-curve but with more fluctuations and irregularities observed in museve compared to mutuluni forest. diameter sizeclass distribution did not differ (p<0.05) across the two forests. therefore human activities significantly impacted on tree density in both forest fragments with high impacts in museve. this study recommends formulation of appropriate protection and conservation strategies, especially for museve, to control tree cutting and increase tree density. keywords: basal area, diameter distribution, forest fragments, human activities, stem density 1. introduction persistent land degradation in arid and semiarid lands (asals) has resulted to fragmentation of forest cover into wide-spread forests fragments “dryland forests” (fao, 2010). according to gachathi (2012) most of these forest fragments in asals are localised around hilltops and hold unique flora and fauna. in addition, they provide vital ecosystem services such as habitat, water catchment, pasture, fuelwood, climate amelioration, medicine, timber and others (gachathi, 2012; kiruki et al., 2017). however, being located in asals, most of these forest fragments are characterized by poor tree density i.e. tree stems per hectare and basal area per hectare (kfs, 2012). moreover, the increasing human population in asals and associated unsustainable land use practices further escalate vulnerability of these fragile ecosystems to degradation and desertification (middleton and thomas, 1997; kigomo, 2003). similarly, museve and mutuluni hill-top forest fragments in kitui are not exceptional. these ecosystems provide important services to the adjacent population like water, pasture, fuelwood, medicinal *correspondence: musaujoshua54@gmail.com issn 2235-9370 print/issn 2235-9362 online ©2019 university of sri jayewardenepura doi: https://doi.org/10.31357/jtfe.v9i1.3955 https://doi.org/10.31357/jtfe.v9i1.3955 90 extracts, climate amelioration and air purification among others. usually, the forest management through kenya forest service (kfs) grants user rights to local communities on forest friendly activities upon agreement between the service and a registered community group (gok, 2005). basic user rights include grazing, grass and fodder harvesting, collection of medicinal herbs, seed collection, fuelwood collection, soil collection, bee keeping, ecotourism and recreational activities etc. (gok, 2005; mbuvi et al., 2010). the museve and kavonge community forest association (cfa) is such a case in which participatory forest management is undertaken in museve forest. however, illegal activities like logging, charcoal burning, fire and grazing have been reported in restricted areas within the forests (mbuvi et al., 2010; musau, 2016). moreover, comprehensive information on tree density and diameter distribution for these forest reserves is not available. according to westphal, et al. (2006), knowledge on diameter structure is an important parameter to guide managerial prescriptions like regeneration and harvesting needs. besides, influences human activities on their tree density and diameter structure has never been evaluated for informed decision making. thus, the two forest reserves risks degradation by adjacent human population that depend on them blindly for livelihoods (mbuvi et al, 2010; gok, 2014). normally, structurally stable forests are expected to have un-even aged mixed trees comprising individuals of all diameter size classes and constant rate of change of trees (the quotient “q”) in successive diameter classes (hett & loucks, 1976; rouvinen & kuuluvainen, 2004). human activities, some of them reported in the study area like tree cutting, overgrazing and introduction of invasive alien species are known to affect forest structure (fao, 2010; mutiso, et al., 2011). cutting of mature trees in particular, may reduce their stem density and seeding capability (omeja et al., 2004; ndah et al., 2014; kiruki et al., 2016). consequently, alter their regeneration potential of the forest resulting to stands of poor tree density and diameter structures (krebs, 1989; hitimana et al., 2004; omeja et al., 2004). accordingly, such altered ecosystems and wildlife habitats may result into adverse and far-reaching effects on biodiversity conservation (mutiso, et al., 2011; kacholi, 2014). therefore, with knowledge regarding the status of tree density and diameter structure of a forested ecosystem, the management can make informed decisions to prevent adverse likely ecosystem effects. hence, it is for this reason that reliable knowledge about stem density, basal area and diameter size-class distribution for museve and mutuluni forest fragments is urgently needed. further assessment of how human activities may have impacted diameter structure of the two forests fragments is equally needed, hence, the importance of this study. reliable information is now available that will provide baseline data and essential knowledge required by forest managers to formulate sustainable forest management plans to effectively conserving museve and mutuluni dryland forests. 2. methodology 2.1 the study area the study was undertaken in museve (48ha) latitude 1o 19/35.94// s and longitude 38o 4/17.81// e and mutuluni (596 ha) latitude 2o 1/0.16// s and longitude 38o 17.64/ e forest reserves, kitui county; kenya (figure 1). both are dryland secondary forest fragments previously owned by local communities but evicted by colonial government in early 1900’s (mbuvi et al., 2010). since then, mutuluni forest was left to recover naturally while museve forest underwent several human interventions including introduction of exotic tree species and enrichment planting by forest management (mbuvi et al., 2010). as a result several remnant exotic species are integrated with natural regeneration in museve forest (musau, 2016). besides museve forest is more close to kitui town and has higher adjacent human population density (197 people/km2) compared to mutuluni forest (24 people/km2) (knbs, 2010). the area receives an annual average rainfall ranging from 750 mm to 1,150 mm distributed in two rainy seasons. annual temperature range between 15.7o c and 27.1o c (menr, 2002; gok, 2014). the geology mainly consists of sedimentary plains which are usually low in natural fertility (moa, 1983). musau and mugo /journal of tropical forestry and environment vol. 9, no. 01 (2019) 89-100 91 popular indigenous tree species in museve and mutuluni forests include: acacia seyal, combretum molle, commiphora africana, teclea nobilis, erythrina abyssinica, azanza gackeana, rhus natalensis, euclea divinorum and antidesma venosum (musau, 2016). figure 1: museve and mutuluni forest fragments; kitui county, kenya. 2.1 data collection four belt transects, two in museve forest and two in mutuluni, each measuring 500 m long and 20 m wide were used. in each forest, the highest point was identified as the start point of the first transect (transect 1) that run longitudinally along the forest stretch. from the start point, a distance of 50 m on the opposite direction was set to separate the two transects and mark the start of the second transect (transect 2) which run in opposite direction. since both forest fragments are strip-like, transects were purposely established in a longitudinal orientation so as to collect as much information as possible. a hand held geographical positioning system receiver was used to locate points of the transect corners. nested sampling design was adopted for this study. in each belt transect, 25 main sample plots of 20 m by 20 m and sub-plots of 10 m by 10 m nested within the main plots were established. this study design was preferred based on data requirements and to facilitate simultaneous collection of different data sets. in each 20 m by 20 m plot data on human activities and mature trees (≥5 cm dbh) was gathered. information collected on human activities included abundances and/or evidences of predetermined human activities. these were; tree cutting, exotic species, grazing, footpaths, fire occurrences, grass cutting, pit sawing, human/livestock tree debarking and charcoal burning. information gathered for mature trees included species identification, abundances and diameter measurements at breast height (dbh). further, in the subplots measuring 10 m by 10 m, data on saplings (1 cm ≥ dbh ˂ 5 cm) data was collected. this consisted of species identification and abundances. only one out of the four 10m by 10m subplots was randomly selected from each 20 m by 20 m main plot. since the study focused only on trees and no other vegetation forms like herbs and shrubs, plant growth characteristics were used to identify tree species and/or distinguish trees from other plant life forms such as shrubs, herbs and grasses. according to kocholi (2014), trees can be regarded as “woody plants” attaining a height of 5 m and above at maturity. expert knowledge and plant growth 92 characteristics from available botanical guides were used in trees species identification. further, the dbh (cm) criteria was used to distinguish mature trees from saplings and seedlings. mature trees were considered as trees attaining 5cm dbh (≥5 cm) while saplings 1 cm dbh and above but less than 5 cm, (1 cm ≥ dbh ˂ 5 cm). seedlings were considered as all tree individuals with less than 1 cm diameter reading at breast height and those with no dbh. 2.2 methods of data analysis comparing levels human activity between museve and mutuluni forests information on human activities was summarized into frequency table, a two-sided test of equality for column proportions using z-test was used for comparison between the two forest fragments. further, the number of trees cut in every 20 m by 20 m plot was converted into stems/ha and used to compare intensity of tree cutting within and across the two forest reserves. effects of human activities on tree density data on tree abundances for mature trees was used to calculate their stem density (stems/ha) while that of diameter measurements used in estimation of basal area density (m2/ha) in each 20 m by 20 m plot. the calculations were in accordance to equation 1 and 2 respectively. the estimated stem density and basal area density data from the two transects in each forest was pooled together and tested for distribution. where the data was normally distributed, t-test statistic was used for comparison within and across the two forests. mann-whitney test statistic was employed for data that did not conform to the normal distribution. (1) (2) where; basal area = 0.00007854d2; d = diameter at breast height (cm) 0.00007854 = constant to investigate the impacts of human activities on basal area and stem density, frequency data on human activities was coded “1” and “0” for presence and absence respectively. these was further regressed as independent input variables against the dependent variables; stem density and basal area density respectively using logistic regression. results were presented in summary tables and inferences made. effects of human activities on stem diameter distribution in order to compare stem diameter distribution between museve and mutuluni forests, all recorded stem diameter measurements were grouped into fifteen diameter size classes. the saplings constituted the lowest diameter class (<5 cm dbh) whereas trees (≥5 cm dbh) were grouped into three centimeter class intervals based on the data collected. the number of stems/ha in each diameter class in both forests was computed by dividing all trees in that diameter size class by the forest area (ha) sampled. a graph of stem/ha against diameter classes was plotted to assess if it conforms to the expected reverse j-curve diameter distribution. the derived data was further fitted to a power function model (equation 3) used in describing diameter distribution in natural forests (hett and loucks, 1976). regression coefficient of determination was then used to assess model fitness in each forest while mann-whitney u test was used to compare stem density-diameter distribution across the two forests. musau and mugo /journal of tropical forestry and environment vol. 9, no. 01 (2019) 89-100 93 (3) where; y = the number of stems or saplings in any diameter class x yᵒ = the initial input into the population at time zero (at the smallest dbh) b = depletion rate with time further, diminution ratio coefficient (the quotient, “q”) or the q factor of trees in successive diameter size classes was calculated (equation. 4). the quotient, “q”was plotted against diameter size classes to compare recruitment of trees in successive diameter size classes (hitimana et al., 2004; meyer, 1943). (4) where; d1-i = density in the lower class di= density in the immediate upper class. 3. results 3.1 types of human activities recorded in museve and mutuluni forests only five out of the nine predetermined indicators of human activities were recorded in both museve and mutuluni forest. the five indicators were: presence of foot paths, grazing, debarking of trees, tree cutting and presence of exotic species. three indicators; presence of foot paths, grazing and tree cutting occurred in both forests while tree debarking occurred in mutuluni whereas presence of exotic species in museve forest. a two-sided z-test of equality for column proportions indicated significant differences (p<0.05) in frequencies of human activities across the two forests with high intensity recorded museve forest (table 1). a t-test further revealed significant difference (t=2.69, p<0.05) in the number of trees cut/ha within museve forest while no difference (mann-whitney test; p>0.05) was observed within mutuluni forest. when compared between the two forests, mann-whitney test indicated a significant (p<0.05) differences in the number of trees cut/ha with high density in museve forest. table 1: types and frequencies of human activities recorded in museve and mutuluni forests. type of human activity count forest museve forest count mutuluni forest count tree cutting 0 01,2 3a 23b 1 01,2 47a 27b grazing 0 01,2 18a 40b 1 01,2 32a 10b human/livestock debarking 0 01,2 502 44a 1 01,2 02 6a footpaths 0 01,2 20a 38b 1 01,2 30a 12b exotic species 0 01,2 3a 50 2 1 01,2 47a 0 2 note: values in the same row and subtable not sharing the same subscript are significantly different at p<0.05 in the two-sided test of equality for column proportions. cells with no subscript are not included in the test. tests assume equal variances. 94 3.2 stem density and basal area density in museve and mutuluni forests the calculated mean stem densities for museve and mutuluni forests were 347.50 stems/ha and 639.50 stems/ha while basal area densities were 5.80 m2/ha and 6.08 m2/ha respectively (figure 2 and 3). within each of the forests, mann-whitney revealed no significant difference in basal area density and stem density (p>0.05). however, there was a significant difference in stems density across the two forests (p<0.05) while basal area density showed no differences (p>0.05). figure 2: comparison of stem densities between mutuluni and museve forests. figure 3: comparison of basal area between museve and mutuluni forests. 3.3 impacts of human activities on basal area and stem density when the frequencies of footpaths, grazing, tree debarking and the number of trees cut/ha and exotic tree species/ha were regressed as predictor variables against stem density, the logistic regression test of parameter estimates indicated that tree cutting and introduction of exotic species had significant effects. cutting of trees significantly reduced stem density in museve forest (b=-0.01, wald χ2=48.26, p <0.05) and mutuluni forest (b<-0.01, wald χ2=4.84, p<0.05). introduction of exotic species on the other musau and mugo /journal of tropical forestry and environment vol. 9, no. 01 (2019) 89-100 95 hand enhanced stem density (b<0.01, wald χ2=19.68, p<0.05) in museve forest (table 2). logistic regression coefficients for grazing, footpaths and tree debarking were not significantly different (p>0.05) and thus they did not have significant effects on stem density (table 2). table 2: test of parameter estimates for stem density in museve and mutuluni forests. forest parameter b hypothesis test wald chi-square df sig. museve forest (intercept) 6.45 2594.60 1 0.00 grazing -0.01 0.02 1 0.88 footpaths -0.16 2.45 1 0.12 trees cut/ha -0.01 48.26 1 0.00 no. exotics species/ha <0.01 19.68 1 0.00 mutuluni forest (intercept) 6.52 294.94 1 0.00 grazing 0.03 0.03 1 0.87 footpaths -0.05 0.05 1 0.83 human/livestock debarking 0.15 0.31 1 0.58 trees cut/ha <-0.01 4.84 1 0.03 when grazing, footpaths, human-livestock debarking, trees cut/ha, number of exotic species/ha were regressed against basal area density, wald chi-square test statistic revealed a significant influence on basal area density in museve forest but not in mutuluni. tree cutting significantly reduced basal area density (b=-0.01, wald χ2=10.79, p<0.05) while introduction of exotic tree species on the other hand enhanced stem density (b<0.01, wald χ2=61.61, p<0.05) in museve forest (table 3). in mutuluni forest, regression coefficients for all parameter estimates were not significantly different from zero (table 3). thus, human activities documented in mutuluni had no significant influence on basal area. table 3: parameter estimates tests for basal area in museve and mutuluni forests. forest parameter b hypothesis test wald chi-square df sig. museve forest (intercept) 1.86 76.57 1 0.00 grazing 0.17 2.16 1 0.14 footpaths 0.02 0.02 1 0.89 trees cut/ha -0.01 10.79 1 0.00 no. of exotic species/ha <0.01 61.61 1 0.00 mutuluni forest (intercept) 1.24 2.11 1 0.15 grazing 0.39 0.78 1 0.38 footpaths -0.20 0.22 1 0.64 human/livestock debarking 0.71 1.09 1 0.30 trees cut/ha -0.01 3.14 1 0.08 3.4 stem diameter size class distribution in museve and mutuluni forests when stem density was plotted against diameter size classes, the shape of the graph followed a reverse j-curve distribution (figure 4). stem densities were high in lower diameter size classes and decreased with increasing diameter sizes. this indicated that trees within the two forest reserves varied in age and that most of the trees were young. there was no significant difference in the distribution of tree stem densities across the diameter classes in both mutuluni and museve forest reserves (mann-whitney test; p>0.05). 96 figure 4: successive diameter size-classes in museve and mutuluni forests. least squares fit of the power function model on scatter plots of stem density against diameter classes revealed strong goodness of fit (r2>0.9) (figure 5). regression coefficients (b) were significantly (p<0.05) different from zero (0) in both forests, a validation that the model could adequately predict and explain more than 90% (r2>0.90) variation in stem density-diameter size distribution in both forests. the q values indicated a fluctuating and irregular curve in both museve and mutuluni forests when plotted against dbh size classes (figure 6). museve forest demonstrated a highly fluctuating and irregular curve compared to mutuluni. figure 5: least squares fit of the power function of stems/ha against dbh in a log-log scale in museve and mutuluni forests. musau and mugo /journal of tropical forestry and environment vol. 9, no. 01 (2019) 89-100 97 figure 6: comparison of q values against diameter size classes in museve and mutuluni forest. 4. discussion from the nine predetermined human activities, only five were recorded. these were tree cutting, introduction of exotic species, grazing, human tree debarking and presence of foot paths. the study could not differentiate illegal activities from the legal ones given the understanding that the forest management allows collaborative forest management with the surrounding community and illegal human activities have also been reported (mbuvi et al., 2010). rather, it focused on documenting information about key human activities across the two forest, tree density, diameter structure and investigate how these human activities (both legal and illegal) has affected tree density and diameter structure. from the five categories of human activities recorded, three were common across the two forests (tree cutting, grazing and presence of foot paths) indicating their prevalence within the study area. these findings are also supported by reports middleton and thomas (1997) that overgrazing and deforestation are the most notable factors to de-vegetation and degradation in sahel countries especially areas falling within asals. in fact, the results revealed that tree cutting resulted into significant reduction on basal area and stem density in both forests. further, the impacts were much bigger in museve forest compared to mutuluni. on average, tree cutting reduced stem density by -0.01stems/ha in museve and <-0.01stems/ha in mutuluni forest. this can be linked to the findings that museve forest recorded higher frequencies of tree cutting compared to mutuluni forest. thus, a reason why museve forest recorded low stem density compared to mutuluni. similar findings have been reported by hitimana et al. (2004), omeja et al. (2004) and kacholi (2014) who indicated that human activities like tree cutting resulted into low tree density and regeneration potential in forest reserves. the estimated basal area of 6.05 m2/ha and 5.82 m2/ha for mutuluni and museve forests respectively was not significantly different across the two forests. this can be attributed to the findings that human activities impacted differently on basal area across the two forests. whereas tree cutting resulted to reduction on basal area, introduction of exotic tree species enhanced basal area in museve forest. in fact, results revealed that on average introduction of exotic tree species enhanced basal area density by <0.01 m2/ha in museve forest. it is worth noting that some of the exotic species (eucalyptus spp and cupressus lusitanica) recorded in museve forest attain high height and large diameter at maturity compared to most of the native species (beenje, 1994). in addition, according to kfs (2009) eucalyptus 98 spp have high coppicing ability and efficiency in water use for biomass accumulation. thus, they resulted to increase in basal area in museve forest, a reason why possibly there was no significant differences in basal area across the two forests. also, the estimated basal area across the two forests was notably low if compared to what has been reported in other tropical forests. this can be linked to the findings that tree cutting resulted into reduction in basal area and the fact that they are located in asals which are associated with poor tree density. this concurs to the findings by mullah et al. (2011) and mutiso et al. (2013) that pressure from deforestation and other human activities has bearing on basal area density. therefore, destructive human activities like tree cutting would increase their vulnerability to forest degradation. being already fragile ecosystems, the impacts are like to be un-proportional. stem-density diameter distribution in both forests followed a reverse j-curve as expected of a natural forest or secondary forests without disturbances for long (leak, 2002; rouvinen and kuuluvainen 2004). according to weiner (1990) this distribution is attributed to factors like gene pool, age, size, competition, growth rate, herbivore and environmental heterogeneity. data from both forests adequately fitted the power function model used in describing diameter distribution in natural or near natural forests (hett and loucks, 1976). therefore both forests were composed of un-even aged trees associated with continuous regeneration and recruitment as reported by davis and johnson (1987) and o’hara (1998). however, the findings that q-values in successive diameter classes deviated from the constant q factor was an indication that the both forests were not structurally stable. structurally stable forests exhibiting a typical reverse j-curve are expected to display constant q factor (meyer, 1943). any deviations or irregularities as exhibited in this study indicate significant influence diameter distribution. according to meyer (1943) and poorter et al., (1996) an irregular and fluctuating q factor indicate absence or insufficient regeneration and recruitment while a regular and fluctuating q factor indicates good but discontinuous regeneration. since disturbances on forest structure can result either from natural causes or human induced activities, it is worth noting that this study focused only on human activities. therefore, possible human activities that may have led to fluctuating q-values include tree cutting and tress species introduction. tree cutting was shown to reduce stem density in the study area which probably affected diameter distribution. according to omeja et al. (2004) tree cutting especially when mother trees are targeted can reduce their density and affect regeneration potential of a forest. this is often the case with trees of high socialeconomic importance is a specific area. hence, resulting into insufficient and/or discontinuous regeneration. tree planting like the deliberate introduction of exotic tree species recorded in museve forest resulted into more irregular and fluctuating q-values observed in the forest. besides, alien species may result to unnecessary competition whereas grazing and footpaths may result to browsing and trampling of seedlings which may influence regeneration and mortality trends of tree individuals in the study area (hitimana et al., 2004; mutiso et al., 2013). hence, influence tree diameter distribution in successive diameter size-classes resulting into fluctuating and irregular q values. the highly fluctuating and irregular q values recorded in museve forest compared to mutuluni indicated that human activities impacted higher on diameter distribution in the forest. this is also in line with the findings that museve forest recorded high intensity of human activities compared to mutuluni forest which also resulted into higher impacts on stem density and basal area. lastly, the findings that the two forests exhibited j-curve diameter distribution despite recording human influences is not unusual. similar studies hitimana et al. (2004) and mutiso et al. (2013) have shown that it is possible for a forest experiencing anthropogenic disturbances to exhibit reverse j-curve diameter distribution. nonetheless, it is important to note that the fitness depends on the nature and extent of such disturbances (leak, 2002). 5. conclusion from the five documented human activities in museve and mutuluni forests, only tree cutting and introduction of exotic tree species significantly impacted stem density, basal area and diameter distribution. museve forest recorded high frequencies of human activities that resulted to greater impacts musau and mugo /journal of tropical forestry and environment vol. 9, no. 01 (2019) 89-100 99 compared to mutuluni forest. presence of grazing, foot paths and tree debarking did not have significant impacts. introduction of exotic species in museve forest enhanced both basal area and stem density whereas tree cutting reduced both basal area and stem density in museve forest. thus, this study concludes that human activities have significant impacts on stem density, basal density and diameter distribution in the two dryland forest fragments. if not checked, this is likely to degrade diameter structure and conservation values of the two forests. therefore, appropriate protection and conservation measures should be urgently put in place especially for museve to control tree cutting and increase tree density. in addition, there is need for further research on the impacts of natural factors to diameter structure on both forests. further, assessment on the effects of introduced exotic species in altering regeneration and ecological processes within dryland forest fragments such as museve forest is needed. acknowledgment authors are highly grateful for the logistical and technical support extended to this work by the kenya forest service (kitui forest station) and kenya forest research institute (kitui and muguga centres). we also acknowledge the input by field crew. references beentje j., 1994. kenya trees, shrubs and lianas. nairobi: national museums of kenya. davis, l.s., johnson, k.n., 1987. forest management. (3rd ed.). new york: mc graw-hill book. company. fao (food agricultural organization), 2010. guidelines on sustainable forest management in drylands of sub-saharan africa; arid zone forests and forestry. working paper no. 1. rome: forest department, fao. gachathi, f., 2012. the other water towers. better globe forestry, 114:20-21. gok (government of kenya), 2005. forest act 2005. laws of kenya in nairobi: government printer. gok (government of kenya), 2014. planning for sustainable socio-economic growth and development. county integrated development plan 2013-2017. kitui county: kitui. hett, j.m. and loucks o.l., 1976. age structure models of balsam fir and eastern hemlock. journal of ecology, 64:1029-1044. hitimana, j., kiyiapi, j. and njunge, j.t., 2004. forest structure characteristics in disturbed and undisturbed sites of mt. elgon moist lower montane forest, western kenya. forest ecology and management, 194:269-291. kacholi, d.s., 2014. analysis of structure and diversity of the kilengwe forest in the morogoro region, tanzania. international journal of biodiversity, 10:1-8. kfs (kenya forest service), 2009. a guide to on-farm eucalyptus growing in kenya. nairobi: kenya forest service. kfs (kenya forest service), 2012. the forester. a quarterly magazine of the kenya forest service. january-march. karura in narobi: kenya forest service. kigomo, b.n., 2003. forests and woodlands degradation in dryland africa: a case for urgent global attention. a paper submitted to the xii world forestry congress in 2003 quebec city canada. (accessed 3 december, 2015) kiruki, h., zanden, e., njuru, p. and verburg, p., 2017. the effect of charcoal production and other land uses on diversity, structure and regeneration of woodlands in a semi-arid area in kenya. forest ecology and management, 391:282-295. kiruki, h., zanden, e., malek, z. and verburg, p., 2016. land cover change and woodland degradation in a charcoal producing semi-arid area in kenya. wiley online library. (accessed 11 october, 2016). knbs (kenya national bureau of statistics), 2010. the 2009 kenya population and housing census. nairobi: government printer. 100 krebs, c.j., 1989. ecological methodology. new york: university of british columbia. leak, w.b., 2002. origin of sigmoid diameter distributions. newton square: u.s. department of agriculture and forest service. mbuvi, m., nahama, e. and musyoki, j.m., 2010. socio-economic report for kavonge and museve hilltop forests. (unpublished consultancy report). kalundu and nzeeu rivers environmental conservation group, kitui. menr (ministry of environment and natural resource), 2002. kitui district forestry master plan. kenya, ministry of environment and natural resources and belgian technical cooperation in nairobi: government printer. meyer, h.a., 1943. management without rotation. journal for forest, 41:126-132. middleton, n.j. and thomas d., 1997. world atlas of desertification. unep, london: arnold. moa (ministry of agriculture), 1983. farm management handbook of kenya. natural conditions and farm management information. east kenya (eastern and coast provinces). nairobi: government printer. mullah, j.c., totland, o. and klanderud, k., 2011. recovery of plant species richness and composition in an abandoned forest settlement area in kenya. a journal of the society for ecological restoration international, 10:1-13. (accessed 20 january, 2015) musau, j.m., 2016. anthropogenic influences on tree species composition, diversity and density: a comparative study of museve and mutuluni forest fragments, kitui county, kenya. (unpublished msc. thesis). karatina university, karatina. mutiso, f.m., hitimana, j., kiyiapi, j.l., sang, f.k. and eboh, e., 2013. recovery of kakamega tropical rainforest from anthropogenic disturbances. journal of tropical forest science, 25:56-57. mutiso, f., mugo, j. and cheboiwo, j., 2011. post-disturbance tree species regeneration and successional pathways in mt blakett and kedowa forest blocks, mau ecosystem, kenya. research journal of environmental and earth sciences, 3:745-753. ndah, n., chia, e., lucha, c. and yengo, t., 2014. population structure and regeneration status of trees used in making wooden mortar and pestle in the takamanda rainforest south west region, cameroon. international journal of plant & soil science, 3:1374-1386. o’hara, k.l., 1998. silviculture of structural diversity. a new look at multi-aged systems. journal of forestry, 96:4-1. omeja, p., obua, j. and cunningham, b., 2004. regeneration, density and size class distribution of tree species used for drum making in central uganda. african journal of ecology, 42:129-136. poorter, l., bongers, f., rompaey, v. and klerk, m., 1996. regeneration of canopy tree species at five sites in west african moist forest. forest ecology and management, 89:101-113. rouvinen, s. and kuuluvainen, t., 2005. tree diameter distributions in natural and managed old pinus sylvestris-dominated forests. forest ecology and management, 208:45-61. weiner, j., 1990. asymmetric competition in plant populations. journal of tropical ecology, 5:360-364. westphal, c., tremer, n., oheimb, g., hansen, j., gadow, k. and hardtle, w., 2006. is the reverse jshaped diameter distribution universally applicable in european virgin beech forests?. forest ecology and management, 223:75-85. 48 geospatial modelling of forest canopy density and landscape assessment in omo biosphere reserve, south-western nigeria z.h. mshelia1,2, a.i. bamgboye3, m.a. onilude4, o.j. taiwo5 1institute of life and earth sciences (including health and agriculture), pan african university, university of ibadan, nigeria 2department of environmental modelling and biometrics, forestry research institute of nigeria, ibadan 3department of agricultural and environmental engineering, university of ibadan, nigeria 4department of wood product engineering, university of ibadan, nigeria 5department of geography, university of ibadan, nigeria date received: 23-04-2021 date accepted: 10-12-2021 abstract forest has an important role in the global carbon cycle that covers over one-fourth of the world’s geographical area. it is one of the major natural resources and magnificent terrestrial ecosystems of the world. forest canopy density (fcd) is imperative in the assessment of forest status and is a primary indicator of potential management interventions. landsat images of 1990 and 2018 were used in this study. remote sensing has demonstrated to be very cost-effective in mapping and monitoring changes in forests, and other environmental issues. forest cover change and fragmentation were analysed using fcd and landscape metrics. the fcd was obtained from the combination of data from the advance vegetation density index (avi), bare soil index (bi), and forest shadow index (fsi). four categories of change were identified in the reserve, no change, growth, degradation and deforestation. there was no change in 222.57 ha (52.98%), growth had 81.54 ha (0.69%), degradation with 116.01 ha (27.61%) and deforestation with the least change with 0.81 ha (0.19%). degradation with a change rate of 0.97% contributed more in terms of change. there is a slight increase in the values of the three diversity indices (shdi, shei, sidi) while a high degree of homogeneity is recorded in the no forest class and the three others classes were fragmented. understanding the dynamics of the forests is important in mitigating climate change and support for biological resources. keywords: fcd, landscape metrics, deforestation, degradation, fragmentation 1. introduction the management of forests as carbon reservoirs could support the protection of biological resources such as water, soil, habitat, and raw materials, etc. (thornley et al., 2000). forest conservation and sustainable forest management are key in mitigating climate change at all scales. farming, industrialisation, urbanisation and mining activities have caused the loss of large forest areas resulting in a high rate of deforestation and forest degradation. forest areas, forest density and greenness of an area are major issues for the ecosystem, biodiversity and so on (banerjee et al., 2014). forest maps are an effective tool for identifying the state of forest resources and monitoring ongoing spatial processes in forested landscapes. one of the most important forest properties is the canopy cover and it provides habitats for many animal species (akike et al., 2016). *correspondence: zackmshelia@gmail.com © university of sri jayewardenepura mshelia et al. /journal of tropical forestry and environment vol. 11 no. 1 (2022) 48-66 49 conventional remote sensing methodology is based on qualitative analysis of information derived from “training areas” (i.e. ground-truth). this has certain disadvantages in terms of the time and cost required for training area establishment, and the accuracy of the results obtained. in response to these problems, a new methodology was developed during itto project pd 32/93 rev. 2 (f), “rehabilitation of logged-over forests in asia-pacific region, sub-project iii” (rikimaru et al., 2002). the forest canopy density (fcd) mapping and monitoring model utilizes forest canopy density as an essential parameter for the characterization of forest conditions. fcd data indicates the degree of degradation, thereby also indicating the intensity of rehabilitation treatment that may be required (rikimaru, et al., 2002). forest cover analysis is the first step in assessing forest fragmentation, as forest cover modifies the fragmentation pattern. there is link between forest fragmentation with forest cover changes (gupta et al., 2018). landscapes are spatial entities of the earth’s surface explicitly defined by their structure, function and composition. they are dynamic geographical units composed of various structured elements that interact at different scales and ranges (rajendran et al., 2015). unlike traditional the ecosystem concept, the landscape concept focus on spatial heterogeneity and its impact on the ecological processes. the ecological processes that maintain complex landscapes at one scale can be different from other scales. understanding the dynamism of landscape characteristics is vital for ecological stability and biodiversity conservation (rajendran et al., 2015). remote sensing has demonstrated to be very cost-effective in mapping and monitoring changes in forests, and other environmental issues (wang et al., 2009). the focus of this study is to access the forest canopy density and landscape pattern of omo biosphere reserve with specific objectives: (i) to examine the forest cover change between 1990 and 2018 using the forest canopy density model; (ii) to examine the rate of forest cover change; (iii) to analyse the forest landscape characterisation using landscape metric model within the study area. 2. methodology 2.1 the study area omo forest reserve, which derives its name from river omo that traverses it, is located between latitudes 6o 42' to 7o 05' n and longitude 4o 12' to 4o 35' e (figure 1) ogun state south-western nigeria. omo covers about 130 500 ha, which includes a 460 ha strict nature reserve established in 1977 known as omo biosphere (okali and ola-adams, 1987). 50 figure.01. location of omo biosphere reserve in omo forest reserve south-western nigeria the climate is tropical and it is characterized by wet (february to november) and dry (december and january) seasons. the temperature ranges between 21-34 °c while the annual rainfall ranges between 150 and 3000 mm (larinde et al., 2011; adedeji et al., 2015). 2.2 data acquisition and analysis landsat satellite images of 5th january 1990 (landsat tm) and 19th january 2018 (landsat 8 oli) in path 190 and row 55, were acquired from the official website of the united states geological survey (usgs). the satellite images obtained were subjected to radiometric calibration to adjust the data for use in quantitative analysis (agbor et al., 2017). the images used in this study were first converted to top of atmosphere (toa) radiance using equation 1 (giannini et al., 2015). mshelia et al. /journal of tropical forestry and environment vol. 11 no. 1 (2022) 48-66 51 lλ= ( (lmaxλ-lminλ) q cal λ ) q cal +lminλ (1) the above expression does not consider the atmospheric effects, therefore there is a need to convert images from radiance to reflectance measures, using equation 2 ((giannini et al, 2015). 2 esun * r*d e *cos sz toa       (2) figure 02. flow chart of the methodology landsat etm 1990 (30m) and landsat oli 2018 (30m) conversion from dn to radiance and reflectance advance vegetation index (avi) bare soil index (bi) canopy shadow index (si) principal component analysis (pca) vegetation density (vd) scale vegetation index (svi) scale shadow index (ssi) forest canopy density (%) land cover classification map based on density change analysis and landscape metrics computation accuracy assessment projection of forest cover classes 52 2.2.1. forest canopy density model the forest canopy density model utilizes forest canopy density as an important parameter for the assessment of forest conditions. this model involves bio-spectral phenomenon modelling and analysis utilizing data derived from four indices (azizia, 2008 and akike, 2016): advanced vegetation index (avi), bare soil index (bi), shadow index or scaled shadow index (si, ssi) and thermal index (ti) (azizia, 2008 and akike and samanta, 2016). the four indices were calculated using equations 3 to 8. 2.2.2. advanced vegetation index (avi) this index was calculated using equations 3 and 4 (azizia, 2008 and akike et al, 2016). 3 b4)}-b4)(b5-1)(65536+ {(b6 = avi for oli (landsat 8) (3) or 3avi = {(b5 +1)(256-b3)(b5-b3)} for etm (landsat 5 or 7) (4) 2.2.3. bare soil index (bi) bi was calculated using equations 5 and 6 (akike et al., 2016 and saei et al., 2000). ( 6 4) ( 5 2) *100 100 ( 6 4) ( 5 2) b b b b bi b b b b         for oli (landsat 8) (5) or ( 5 3) ( 4 1) *100 100 ( 5 3) ( 4 1) b b b b bi b b b b         for etm (landsat 5 or 7) (6) 2.2.4. shadow index (si) si was calculated using equations 7 and 8 3si = ((65536 +b2) * (65536-b3) * (65536-b4)) for oli (7) or 3si = ((65536 +b1) * (65536-b2) * (65536-b3)) for etm (8) the source of thermal information is the infrared band of landsat data (bands 6 and 10). land surface temperature (lst) retrieval was carried out through three phases (giannini et al., 2015). all the image bands are quantized as 8-bit data except landsat 8 which is 16 bit, thus; all information is stored in dn which were then converted to radiance with a linear equation (9) given as: y= mx + b (9) where: y=toar (top of atmosphere) radiance-the radiance measured by the sensor m=radiance multiplicative value x=raw band b=radiance additive value by applying the inverse of the planck function, thermal bands radiance values were converted to a brightness temperature value using equation 10 (giannini et al., 2015). this is satellite temperature in kelvin. mshelia et al. /journal of tropical forestry and environment vol. 11 no. 1 (2022) 48-66 53 2 1 ln 1 k bt k toar           (10) where: bt=º kelvin toar=top of atmosphere radiance k1=calibration constant 1 (607.76 for tm), (666.09 for etm+) and (774.89 for oli band 10) k2=calibration constant 2 (1260.56 for tm), (1282.71 for etm+) and (1321.08 for oli band 10) surface temperature=bt–273.15 2.2.5. vegetation density (vd) the principal component analysis was used to calculate the vegetation density (vd) by synthesizing advanced vegetation index with the bare soil index. the value was scaled from 0 to 100%. the 100% shows the area of the high forest while the 0% indicate the areas of no vegetation (rikimaru, 1996; saei and abkar, 2004). 2.2.6. scaled shadow index (ssi) ssi is was calculated from the canopy shadow index (si) by using a linear transformation. the value of ssi was also scaled from 0 to 100%. ssi by 100% responds with the highest possible shadow whereas 0% responds the opposite. si is important in forestry and crop monitoring because the canopy shadow provides some information on tree and plants arrangement. 2.2.7. integration process to achieve fcd model integration of vd and ssi means transformation for forest canopy density value. both parameters have dimensions and have percentage scale units of density. it is possible to synthesize both indices safely by employing the corresponding scale and unit of each. fcd was calculated using equation 11. . ( * 1) 1fcd svd ssi   (11) 2.3. landscape metrics and diversity analysis several studies in landscape ecology emphasized the use of spatio-temporal satellite data along with landscape metrics in landscape evaluation and policymaking. remote sensing data will be primarily utilized to create the necessary database for two time periods, 1990 and 2018. landscape metrics and diversity analysis. the lecos plugin in quantum gis (qgis) was used for the land metrics and diversity analysis. the result of the forest canopy density model of 1990 and 2018 was the input images for the analysis. shannon diversity index expresses, simpson diversity index and shannon evenness index (equitability) was used to determining the level of diversity and evenness in the omo biosphere and the entire reserve. the degree of fragmentation and dominance or homogeneity was examined using the following indices land cover, landscape proportion, edge length, number of patches, patch density, greatest patch area, landscape division, effective mesh size and splitting index. calculated coefficients can be classified according to the type of evaluated characteristic into categories of indices: of shape, size, diversity, edges and proximity (stejskalova et al., 2012). statistically, many of the metrics are correlated and can be depicted in concise form according to the structural characteristics (rajendran et al, 2015). table 1 shows the indices, acronyms used and a short description of each indicator. 54 table 01. landscape metrics used in the study metric abbreviation description land cover lc equals the number of cells for each class based on a classified land cover matrix. the resulting values were multiplied by the cell’s value; (ha) landscape proportion lp landscape proportion (lp) quantifies proportional abundance of a certain class in the total landscape area(0<lp≤100); % edge length el equals the total length of all patches from a specific class. the resulting values were, of course, multiplied with the cell’s value; (m). edge density ed edge density equals the sum of the lengths of all edge segments involving the corresponding patch type, divided by the total landscape area ; (m/ha) number of patches np express the number of patches identified for each class; (no.). patch density pd equals the number of patches of the corresponding patch type divided by total landscape area; (no. /100 ha). greatest patch area gpa greatest patch area identifies the area under the single largest patch in a given landscape. it is a measure of dominance i.e. degree of homogeneity mean patch area mpa the mean patch area serves as a fragmentation index. a landscape with a smaller mean patch area for the target patch type than another landscape might be considered more fragmented. over all core area oc total core area (ha) or the percentage of the landscape comprised of core area at the class or landscape level. the core area is a compound measure of shape, area and edge depth landscape division ld landscape division is defined as the probability that two randomly chosen places in the landscape to be found in the same patch. effective mesh size m the probability that two randomly chosen cells are connected (to be included into the same patch); (ha). splitting index s the number of patches one gets when dividing the total region into parts of equal size in such a way that this new configuration leads to the same degree of landscape division desired; (nr.). shannon’s diversity index shdi based on information theory; represents the amount of "information" per individual (or patch type, in this case); larger values indicate a greater number of patch types and/or greater evenness among patch types. shannon equitability index shei shannon equitability (evenness) index expresses the dominance of patches within the total area. mshelia et al. /journal of tropical forestry and environment vol. 11 no. 1 (2022) 48-66 55 simpson diversity index sidi simpson diversity index represents the probability that any two pixels selected at random would be different patch types. the larger the value the greater the likelihood that any 2 randomly drawn cells would be different patch types 3. results 3.1 forest cover change analysis the results of the advance vegetation index (avi), bare surface index (bsi), shadow index (si), thermal index (ti) and the forest canopy density (fcd) for 1990 and 2018 are presented in figures 03, 04, 05, 06 and 07 respectively. the advance vegetation index (avi) shows a positive relationship with the quantity of vegetation, which means the number of vegetation increases as the value of the avi increases (figure 03). the colours green and yellow are areas covered by vegetation while the colour red shows areas of non-forest which was mosaic of water body, rock outcrop and open space. as shown in figure 4. bare surface index (bsi) increases as the percentage of bare soil exposure of ground increases. the bsi showed the colour red as non-forest to determine the effect of soil exposure in the analysis. this index helps in separating the vegetation with a different background. this result showed that there were no remarkable changes in soil percentage over the years. the si was utilised for spectral information on the forest shadow itself and thermal information on the forest influenced by the shadow. the si takes care of the cooling effect inside the forest and evaporation from the leaf structure. the tree arrangement has a low shadow casting than matured tree arrangement. the result in figure 5 showed that there were no remarkable changes in shadow percentage created by tree canopy over the years. inside the forest stand, the canopy cover blocked the incoming solar radiation and it is the reason for the cool temperature inside the forest. the soil area is characterised by high temperatures. the combination of the thermal index (ti) with shadow index (si) was helpful in black soil detection. the result shows that changes in the land surface temperature over the years in the omo biosphere was insignificant (figure 06). the forest canopy density model integrates these indices to take into account all factors responsible for deficiency in using a single vegetation index to analyse forest cover. the avi and bsi both have a negative relationship with each other, a high avi value shows high vegetation vigour, and similarly, high bsi shows soil exposure. utilising the various spectral indices, vegetation density and scale shadow index, the forest canopy density map was produced for the years 1990 and 2018. it was thereafter utilised for the classification of the forest cover and its change detection. based on the percentage, each pixel was classified into four classes of forest canopy density: high forest density, mid forest density, low forest density and no forest. high forest density is an area having a value from 71% to 100%. in the same manner, 41-70%, 5-40% and below 5% were areas with mid forest density, low forest density, and no forest respectively (figure 07). the maps described the distribution of forest resources in omo biosphere through the fcd model. the statistics in table 02 revealed that from 1990 to 2018, the no forest area decreases by 2.7 ha at the rate of 0.023% in omo biosphere being a strict nature reserve, which could be a result of forest regeneration. the changes in low forest areas are insignificant as the difference between 1990 and 2018 was 0.36 ha. the mid forest density had a significant increase of 42.66 ha at 0.36% change rate from 39.2% to 49.3% while the high-density area was the victim of the great increase in the mid forest density. it reduces from 221.58 ha to 181.98 ha at 0.34 change rate from 52.58% to 43.32%. 56 figure 03. advance vegetation index of 1990 (a) and 2018 (b) of omo biosphere figure 04. bare soil index of 1990 (a) and 2018 (b) omo biosphere mshelia et al. /journal of tropical forestry and environment vol. 11 no. 1 (2022) 48-66 57 figure 05. shadow index of 1990 (a) and 2018 (b) of omo biosphere figure 06. thermal index of 1990 (a) and 2018 (b) of omo biosphere 58 figure 07. forest canopy density of 1990 (a) and 2018 (b) of omo biosphere table 02. area of forest cover classes of omo biosphere reserve class 1990 area (ha) % 2018 area (ha) % area diff. (ha) change rate (%) no forest 8.64 2.057 5.94 1.414 -2.7 0.023 low forest density 25.56 6.084 25.2 5.998 -0.36 0.003 mid forest density 164.34 39.117 207 49.271 42.66 0.362 high forest density 221.58 52.742 181.98 43.316 -39.6 0.336 total 420.12 100 420.12 100 _ _ figure 08. area of forest density classes of omo biosphere 0 50 100 150 200 250 no forest low forest density mid forest density high forest density a r e a ( h a ) 1990 area (ha) 2018 area (ha) mshelia et al. /journal of tropical forestry and environment vol. 11 no. 1 (2022) 48-66 59 3.2. accuracy assessment accuracy assessment of the classified image has been verified from field verification data table 03. the overall accuracy for classification was 90% and 92.8% and kappa statistics of 86.2% and 90.2% for 1990 and 2018 respectively. table 03. kappa statistics of the classified images 1990 2018 class name pa ua pa ua no forest 100 100 81.8 90 low forest density 86.67 81.25 93.3 93.3 mid forest density 88 91.67 95.8 92 high forest density 90 90 95 95 overall accuracy 90 92.8 kappa statistics (k) 86.2 90.2 *pa=producer’s accuracy *ua=user’s accuracy 3.3. forest cover change detection of omo biosphere reserve classified forest canopy density images in 1990 and 2018 were cross-classified and a tabular matrix (table 4) shows the number of pixels that correspond to each combination of categories in the two (column-row) images was compared. the tabular matrix is expressed in terms of the proportion of the total number of pixels. from table 5, four categories of change were identified in the omo biosphere; no change, growth, degradation and deforestation. there was no change in 222.57 ha (52.98%) of the biosphere, no forest to low forest density, low forest density to mid forest density and mid forest density to high forest density growth occurred in 81.54 ha at a change rate of 0.69. 116.01 ha of the forest were degraded from high-density forest to mid-density and from mid-density to low density, which is 27.61% of the reserve. figure 10a showed the change map of the biosphere from 1990 to 2018. the colour blue on the map represent areas that were no forest, low forest, mid forest and high forest densities in 1990 and are still the same in 2018 while the colour black on the map represent areas that were changed from one class to another. figures 10b, c and d were the different changes that the forest went through for 28 years. figure 10b showed the portion of the reserve that grows from no forest area to low forest, mid forest and high forest while figure 10c showed the areas that went through degradation from high forest to mid forest and low forest. figure 10d showed a little portion of the reserve toward the eastern part of the biosphere that was deforested, that is, moving from low forest to no forest class. 60 figure 09. forest canopy density change from 1990-2018 in omo biosphere figure 10a-d. spatial distribution of changes of the four classes (no change (a), growth (b), degradation (c) and deforestation (d) from 1990-2018 in omo biosphere mshelia et al. /journal of tropical forestry and environment vol. 11 no. 1 (2022) 48-66 61 table 04. cross-classification change of 1990 and 2018 in omo biosphere table 05. summary of the area cross-classification change of 1990 and 2018 in omo biosphere 3.4. landscape metrics and diversity analysis table 06 shows the values resulting from the calculation of global indices performed for the two periods. in terms of diversity, there is a slight increase and decrease of the values of the three indices (shdi, shei, sidi) in the biosphere and the entire reserve, as a result of the increase of some classes are reported to the general distribution of the landscape. the slight decrease of the diversity values can be explained by an increase of the mid forest density which accounts for 49.3% of the biosphere (table 02). however, the values of diversity and evenness remain relatively high, suggesting that the study area, which has favourable physical and geographical conditions, has a complex landscape with certain dominant species. in terms of landscape configuration, features and functionality, some other landscape indices were calculated (table 07). unlike diversity indices, these were applied particularly to each class. table 01 presents the indicators, the abbreviation used and a short description for each type. land cover (lc) and landscape proportion (lp)-significant changes were observed in the four classes both in the biosphere especially in mid forest density and high forest density classes. the edge length (el) and edge density (ed)-the result showed a decrease of the two indices values for most classes, suggesting a tendency of landscape homogenization in the biosphere and an increase of the two indices values for most classes tending towards heterogeneity. number of patches (np) and patch density (pd)-a significant decrease was observed in mid forest density (mfd) of the biosphere from 120 to 47. this explained why mfd occupied 49% of the biosphere. all the classes in the omo forest reserve had a decrease in pd except the no forest. patch density reflects the extent of landscape fragmentation and therefore crucial for landscape structure assessment. comparison of classes with varying sizes showed decreasing pd in most of the classes, especially in the entire reserve. however, the rate of the decrease is moderate, thereby making the level category area (ha) % change rate no change 222.57 52.978 growth from nflf-md-hf 81.54 19.409 0.693 degradation from hf-md-lf 116.01 27.614 0.986 deforestation from lf-nf 0.81 0.193 0.007 total 420.12 100 class 1900 class 2018 changes number of pixels area (ha) % no forest no forest nf-nf 57 5.13 1.2211 no forest low forest density nf-lf 24 2.16 0.5141 no forest mid forest density nf-mf 10 0.9 0.2142 no forest high forest density nf-hf 5 0.45 0.1071 low forest density no forest lf-nf 9 0.81 0.1928 low forest density low forest density lf-lf 51 4.59 1.0925 low forest density mid forest density lf-mf 169 15.21 3.6204 low forest density high forest density lf-hf 55 4.95 1.1782 mid forest density low forest density mf-lf 137 12.33 2.9349 mid forest density mid forest density mf-mf 1046 94.14 22.408 mid forest density high forest density mf-hf 643 57.87 13.775 high forest density low forest density hf-lf 68 6.12 1.4567 high forest density mid forest density hf-mf 1075 96.75 23.029 high forest density high forest density hf-hf 1319 118.71 28.256 62 of fragmentation insignificant for now. it was further explained following also the values of edge density. edge density, with patch number and patch density, are representative for establishing the fragmentation degree of the landscape. the values obtained for the fragmentation (np and, consequently, pd and ed) reveal a decrease in the study area’s fragmentation degree, inducing a clustering tendency. the greatest patch area (gpa) is related to the degree of homogeneity or dominance of the landscape. the results in table 8 show that the high forest density (hfd) class with 1,244,700 m has the highest gpa in 1990 while mid-density forest (mfd) has the highest for 2018 with 1,748,700 m in the biosphere. the mean patch area is also higher for the categories mentioned above. landscape division, effective mesh size and splitting index (ld, m and s) are interconnected and measure the fragmentation degree of the landscape. these indicators were introduced by (jaeger, 2000), as a result of the criticism over the simple measurements such as patch number or patch density, which presents some limitations for certain phases of the fragmentation process. they have the advantage, unlike other conventional indicators, that any omissions or additions of other small-sized patches do not influence the final result. in this study, values of ld for all classes are high (above 0.9), reflecting a high degree of fragmentation of class types. although landscape division and mesh are perfectly correlated, inversely, both metrics are included because of the differences in units and interpretation. split (s) is based on the cumulative patch area distribution and is interpreted as the effective mesh number, or several patches with a constant patch size when the corresponding patch type is subdivided into s patches, where s is the value of the splitting index (mcgarigal et al., 2002). jaeger (2000), defines the splitting index as the number of patches that resulted after dividing the total area into equal size parts so that this new configuration leads to the same degree of landscape division (ld). when its value is 1, the landscape is represented by a single patch, the value increasing as the landscape is divided into several patches. considering these aspects, the interpretation of the result must take into account the correlation of these three complementary indicators. the resulting values of the three indicators suggest different degrees of fragmentation for each class. thus, the areas with a high degree of homogeneity are represented by mfd with a change record of 75,130.67 m in 1990 to 730,376.51 m in the omo biosphere. in the entire reserve, a high degree of homogeneity is recorded in the no forest class and the three others classes were fragmented. table 06. landscape diversity indices between 1990 and 2018 of omo biosphere metric 1990 2018 shannon’s diversity index 1.249 0.941 shannon equitability index 0.776 0.678 simpson diversity index 0.685 0.566 61 table 07. landscape metrics computed for class types for 1990 and 2018 in omo biosphere class lc (m) lp (%) el (m) ed np pd gpa (m) mpa (m) ld m (m) s nf 1990 86,400 0.012 5,940 0.0009 15 2.17e-06 34,200 5760 1 229.24 30,210.73 nf 2018 59,400 0.014 4,800 0.0011 10 2.38e-06 26,100 5,940 1 211.31 19,881.59 lfd 1990 25,5600 0.037 26,160 0.0038 123 1.78e-05 19,800 2,078 1 197.19 3,512,0.42 lfd 2018 252,000 0.06 24,120 0.0057 103 2.45e-05 27,000 2,447 1 450.39 9328.01 mfd 1990 1643,400 0.237 111,360 0.0161 120 1.73e-05 691,200 13,695 0.99 75130.76 92.18 mfd 2018 2,070,000 0.493 106,500 0.0253 47 1.12e-05 1,748,700 44,043 0.83 730376.6 5.75 hfd 1990 2,215,800 0.32 99,300 0.0143 66 9.53e-06 1,244,700 33,573 0.96 300081.4 23.08 hfd 2018 1,819,800 0.433 91,200 0.0217 85 2.02e-05 722,700 21,409 0.95 223219.3 18.82 63 62 4. discussion the knowledge of land use and land cover is important for many planning and management activities as it is considered an essential element for modelling and understanding the earth feature system (akike et al., 2016). the result above reveals the capacity of the biosphere to sequestered carbon because the high and mid forest densities have the highest area occupied by forest over the years. although, the result showed the biosphere suffered forest degradation rather than deforestation which can be attributed to logging or physical factors of rainstorm uprooting aged trees as noticed during the fieldwork. after logging, natural regeneration of a secondary forest takes place and can revert carbon (c) losses to recovering c stocks at a certain point in time (henry et al., 2011). very few studies reported the natural capacity of african ecosystems to regenerate after perturbations. kotto‐ same et al., (1997) reported that about 74 % of aboveground c was regenerated after a period of fallow of 18 years. according to the regression between the time of fallow and c stocks, the total system c would be equal to the original natural forest after 24 years (kotto‐same et al., 1997). in a semi‐ deciduous forest of ghana that was logged in the 1950s, inventory of forest with three types of forest management revealed that there was no significant difference in aboveground biomass among a natural protected forest, a forest that was logged in the 1950s and forest that was under tree shelter‐wood system in the 1950s (bombelli et al., 2009). henry et al., (2011) reported that the increasing pressure of the timber companies and the farming activities often does not allow the forest to regenerate. but it is very difficult to estimate this. extensive human encroachment, fragmentation and conversion of natural forest habitat quickly transformed the natural landscape into a cultural landscape at the foot of bhutan and bengal (chamling et al., 2020). the degree of landscape fragmentation is an important environmental indicator in the fields of biodiversity and sustainable development. in addition, information on the degree of landscape fragmentation is relevant in regional planning and for decisions about infrastructure placement or removal. its analysis on different time series shows how strong the current trends are and what their direction is (jaeger et al., 2006). this fundamental research will definitely help to make policy framing holistic management approach. 5. conclusion forest conservation and sustainable forest management is key in mitigating climate change at all scales. the fcd model and landscape metrics analysis using the remote sensing and gis technologies to estimate forest loss and degradation in this study has been noted to be a time and costeffective method. the result showed that the rate of forest degradation is more than deforestation in the reserve. a high degree of homogeneity is recorded in the no forest class and the three others classes were fragmented while values of diversity and evenness remain relatively high, suggesting that the study area, which has favourable physical and geographical conditions, has a complex landscape with certain dominant types. the study determined that forest canopy density and diversity and fragmentation model are important for analysing the spatio-temporal condition of the forest. this will help forest managers in decision making, monitoring biodiversity and conversation planning for sustainable forest management. given the importance of natural forested areas and the pursuit to maintain sustainable forest management in the midst of growing natural resources extraction and other anthropogenic activities, the use of the fcd model and landscape ecology analysis to assess, estimate and quantify forest is recommended for use in forest management activities as it has proven to be a time and costeffective method. 64 64 mshelia et al. /journal of tropical forestry and environment vol. 11 no. 1 (2022) 48-66 63 acknowledgements this work is supported financially by the african union under the pan african university scholarship. references alexiades, m.n. 1996. collecting ethnobotanical data: an introduction to basic concepts and techniques. advances in economic botany, 10:53-94. anderson, t. 1860. acanthaceae. in: thwaites, g.h.k. (ed.) enumeratio plantarum zeylaniae 3. dulau & co., london: 161-240. ashton, p.s. & gunatilleke, c.v.s. 1987. new light on the plant geography of ceylon. 1. historical plant geography. journal of biogeography, 14:249-285. blume, c.l. 1826. bijdragen tot de flora van nederlandsch indie 14. batavia. ter lands drukkerij, batavia:781. bremekamp, c.e.b. 1944. materials for a monograph of the strobilanthinae. verhandelingen der nederlandsche akademie van wettenschappen afdeeling natuurkunde, tweede sectie, 41(1):1-305. carine, m.a., jayasekara, p. and scotland, r.w. 2000. a new species of strobilanthes blume (acanthaceae) from sri lanka. kew bulletin, 55(4):971-976. clarke, c. b. 1884. acanthaceae. in: hooker, j.d. flora of british india, 4. l. reeve & co., london: 429-477. deng, y. f. 2019. transfer of the philippine species of hemigraphis nees to strobilanthes blume (acanthaceae). phytotaxa, 404 (5):1-3. hu, j.q., deng, y.f. & wood, j.r.i. 2011. strobilanthes. in: wu, z.y., raven, p.h. & hong, d.y. (eds.) flora of china 19. science press,beijing & missouri botanical garden press, st. louis:381-429. janzen, d.h. 1976. why bamboos wait so long to flower. annual review of ecology and systematics, 7:347-391. josekutty, e.j., p. biju, j. r.i. wood and j. augustine. 2018 strobilanthes kannanii–a new species of acanthaceae from the western ghats, india. nordic journal of botany, 36:01689. mabberley d.j. 2017. mabberley’s plant-book: a portable dictionary of plants, their classification and uses. 4th edition. cambridge university press, cambridge:1102. mascarenhas, m.e. and m.k. janarthanam. 2013. taxonomic status of strobilanthes warreensis (acanthaceae), an endemic species of western ghats, india. rheedea, 23:1-6. nees von esenbeck, c.g. 1832. acanthaceae indiae orientalis. in: wallich, n. (ed.) plantae asiaticae rariores 3. treuttel, würtz & ritter, london:70-117. nilanthi, r.m.r., samarakoon, h., jayawardana, n., wijesundara, s. and bandaranayake, p.c.g. 2021 strobilanthes medahinnensis (acanthaceae) a new species, based on morphological and molecular data, from the peak wilderness nature reserve, sri lanka. phytotaxa, 514(1):2638. patil, s. 2021. strobilanthes pushpagiriensis (acanthaceae): a new species from western ghats, india. nordic journal of botany, 39(5). powo 2019. plants of the world online. royal botanic gardens, kew <www.plantsoftheworldonline.org/>. somasekaram, t. 1988. national atlas for sri lanka. survey department colombo, pp. 1-141. vahl, m. 1794. symbolae botanicae. 3. moller, copenhagen: 147. venu, p. 2006. strobilanthes blume (acanthaceae) in peninsular india. botanical survey of india, kolkata:216. wood, j.r.i. and scotland, r.w. 2009 new and little-known species of strobilanthes (acanthaceae) from india and south east asia. kew bulletin, 64:3-47. wood, j.r.i. 1994. notes relating to the flora of bhutan: xxix. acanthaceae, with special reference to strobilanthes. edinburgh journal of botany, 51(2):175-273. 65 64 wood, j.r.i. 1995. notes on strobilanthes for the flora of ceylon. kew bulletin, 50(1):1-24. wood, j.r.i. 1998. strobilanthes. in: dassanayake, m.d. (ed.), a revised handbook to the flora of ceylon. a.a balkema, rotterdam:30-74. wood, j.r.i. 2014. new names and combinations in indian acanthaceae novon: a journal for botanical nomenclature, 23(3):385-395. wood, j.r.i., borah, d. and taram, m. 2021. the rediscovery of strobilanthes tubiflos (acanthaceae) in north east india. kew bulletin, 76:333-338. 66 chukwu et al. /journal of tropical forestry and environment vol. 07, no. 01 (2017) 43-53 43 crown-stump diameter model for parkia biglobosa benth. species in makurdi, benue state, nigeria o. chukwu*1, j.h. dau2 and j.u. ezenwenyi3 *1, 3department of forest resources management, university of ibadan, ibadan, nigeria 2department of forest production and products, university of agriculture, makurdi, nigeria date received: 09-03-2017 date accepted: 06-04-2017 abstract the crown of tree is the centre of physiological activity which gives an indication of the potential photosynthetic capacity on a tree. though, its measurement remains a challenge in forest inventory task. the ability to predict crown diameter from stump diameter provides an effective technique of obtaining its estimate. this helps in detecting the excessive tree felling than actual requirements and wildlife suitability.the main objective of this study was to develop and test crown diameter prediction models for silvicultural management of naturally grown parkia biglobosa within the university of agriculture, makurdi. nine 100 m x 100 m temporary sample plots were established using simple random sampling method. crown diameter and stump diameter were measured in all living p. biglobosa trees with stump diameter ≥10.0 cm. least square method was used to convert the counted stumps into harvested crown dimension. three linear and three non-linear models using stump diameter as the exploratory variable were developed and evaluated using the adjusted coefficient of determination (adj.r2), standard error of estimate (see), prediction error sum of squares (press) and akaike information criterion (aic). the crown-stump diameter relationship was best described by the double logarithmic function with 𝐴𝑑𝑗. 𝑅2 = 65.1%, 𝑆𝐸𝐸 = 0.1729, 𝑃𝑅𝐸𝑆𝑆 = 262.9998𝑎𝑛𝑑 𝐴𝐼𝐶 = 717.56.the result showed that crown diameter estimation was feasible even when the only information available is stump diameter.the resulting equation was tested for validation with independent data obtained from additional plots and was found to be desirable for estimating the crown diameter for parkia biglobosa in makurdi, benue state, nigeria. keywords: stump diameter, crown diameter, parkiabiglobosa, double logarithmic, economic trees 1. introduction diameter at breast height (dbh) and crown diameter are important tree characteristics. some variables such as diameter at breast height and stump diameter are easy to measure with simple instruments and it is widely used in forest inventories. however, a number of studies have shown that other variables which are not so easily obtained are also good predictors of forest dynamics and they can improve the reliability of tools like growth and yield models. one of these variables is crown diameter, which has received increasing attention as a means to estimate tree growth (bragg, 2001; adesoye and ezenwenyi, 2015). the crown of tree is the centre of physiological activity, particularly gas exchange, which drives growth and development (leites and robinson, 2004).when natural or anthropogenic stresses impact a forest, the first signs of deterioration may be observed in the tree crowns. thus, measurement of a tree crown is often used to assist in the quantification of tree growth (kozlowski et al., 1991; popoola and adesoye, 2012; adesoye and ezenwenyi, 2015). dubravac et al. (2009), stated that crown of tree is one of the most important elements of tree structure. hence, tree crown diameter still *correspondence: onye20042000@yahoo.com tel: +2348032633835 issn 2235-9370 print / issn 2235-9362 online ©2017 university of sri jayewardenepura 44 remains one of the most difficult tasks in forest inventory. it is relevant in studies of stands growth, and the density of trees in a stand (hemery et al., 2005). despite the important of this tree part, little attention has been given on tree crown diameter in forest inventory and measurement. various reasons could necessitate the reconstruction of sizes of removed trees. these reasons include; reviewing harvesting practices, assessing damage due to catastrophic events, creating historical records of past management activities, and establishing loss due to timber trespass (corralrivas et al., 2007; westfall, 2010). previous studies have shown that tree crown diameter (cd) is well correlated with tree bole diameter (kigomo, 1991; gering and may, 1995; kigomo, 1998; lockhart et al., 2005; hemery et al., 2005). in the same vein, stump diameter (dst) is highly correlated with diameter at breast height (dbh), and as such have being used in place of dbh to predict most tree growth variable especially in the case of illegal logging (osho, 1983; westfall, 2010; özçelík et al., 2010; shamaki and akindele, 2013). functions which predict crown diameter using other growth variables such as stump diameter are tools that can be used by forest managers to provide accurate and timely information on current growing stock since crown diameter models can predict growth and yield of the forest. crown diameter models are needed for interpreting forest inventories of growing stock and for determining the cultural treatment to be employed. according to sprinz and burkhart (1987), the advantage of using crown characteristics as a basic modelling unit is the growth relationships that exist between the tree crowns and stem. crown dimensions and development may be affected by spacing, stand density, or the cultural treatment carried out in the reserve such as thinning which also affect the stem. if the effects of cultural treatments on crown development are quantified, then it is possible to better understand and estimate treatment effects on stem and stand characteristics. there is need to evolve an indirect method of predicting crown diameter (cd) of trees from stumps, which should be accurate and easily applicable. this can help in detecting the oversize markings and undersize recordings of trees and also excessive felling than actual requirements. this can be possible by using the regression and correlation studies between stump diameter as independent variable and crown diameter as dependent variable. the aim of this study was to develop a crown diameter prediction models for p. biglobosa grown within the university of agriculture, makurdi. the results served as tools in ascertaining stump diameter from aerial photographs and as an aid stand in structure determination and silvicultural practices. 2. material and methods 2.1 tree species description parkia biglobosa is common around villages in the savannah areas of west africa where it is left standing when land is cleared or sometimes planted (hutchinson and dalziel, 1963). it is a dicotyledonous angiosperm, belonging to the family fabaceae (alabiet al., 2005). the plant is categorized under vascular plants; it is a deciduous perennial plant that grows up to between 7 and 20 meters height in some cases up to 30 meters (ntui et al., 2012). the tree species commonly referred to aslocust beans, “daddawa”, “ogiri” and “iru” in hausa, igbo and yoruba languages of nigeria respectively, has several uses, including fodder, food, medicine, green manure, fuel wood, timber and economic purposes (elly and joseph, 2012). the cultivation of parkia biglobosa can be seen as an important economic activity for many developing countries (teklehaimanot, 2004). hence, this species was selected for this present study based on its economic values to north and south-western parts of nigeria. chukwu et al. /journal of tropical forestry and environment vol. 07, no. 01 (2017) 43-53 45 2.2 study area this study was carried out in the university of agriculture makurdi, benue state, nigeria. it is located between longitudes 8° 21ˈ to 9° e and latitude 7° 21ˈ to 8° n in benue state, within the southern guinea savannah ecological zone of nigeria and covers a total land area of 7,978 km2. the topography of the study area is characterized by gentle hills. the soil is mainly sandy-loamy; the climate is characterized by distinct rainy and dry seasons. the annual rainfall ranges between 1016 mm to 1524 mm spreading over may to october. the climate of the area is tropical sub-humid with high temperatures and high humidity; the average maximum and minimum daily temperature of 35°c and 21°c in wet season, and 38°c and 16°c in dry season. the study area is bounded at the northeast by guma local government area and by river benue in the south (gyang, 1997). 2.3 sampling procedure and data collection this study was carried out in temporary sample plots of parkia biglobosausing simple random sampling technique in makurdi, benue state, nigeria. nine (9) temporary sample plots (tsps) of size 100 m × 100 m were randomly selected within the study area. all living trees with stump diameter (dst) ≥10.0 cm within each randomly selected sample plot were measured. the following tree growth variables measured were stump diameter (cm), diameter at breast height (cm) and crown diameter. a total number of two hundred and sixty-five (265) trees were measured in all the nine selected plots. 2.4 crown diameter the tree crown diameter measurements were based on the assumption that the vertical projection of a tree crown is circular. four radii were measured and in the direction forming equal angles (krajicek et al., 1961; foli et al., 2003; zuhaidi, 2009).tree crown diameter was measured by projecting the diameter of the crown with ranging poles on the ground at four different directions and taking the distance between the ranging poles using measuring tape calibrated in meters. the crown diameter was then obtained by taking the average of the two readings recorded from the four directions for each tree. the average crown diameter (cd) was then calculated as such: 𝐶𝑑 = ∑ 𝑟𝑖 2 (1) where, 𝐶𝑑 = average crown diameter, 𝑟𝑖 = projected crown radii measured on four axis 2.5 tree diameter stump diameter (dst) was measured for all the living tree individuals ≥ 10.0 cm at the height of 0.3 m and diameter at breast height was measured at the height of 1.3 m. the point of the measurement was recorded from the uphill sides of the trees and on the inside of the lean for leaning trees. for trees with deformations at 0.3 m, the measurement was made at the sound point on the stem above the abnormality. for buttressed trees, a point of measurement was selected approximately 0.5 m above the convergence of the buttress (huschet al., 1982). diameter measurements of trees were recorded using a metal metric diameter tape graduated in centimeters. during the measurement, loose bark, climbers and epiphytes were lifted above the measuring tape. 46 2.6 crown projection area based on the calculated or predicted cd, the crown projection area (cpa) can be calculated and expressed in ha (krajicek et al., 1961): 𝐶𝑃𝐴 = 𝜋𝐶𝐷2/10000 4 (2) where, cd = crown diameter (m) 𝜋 = pi (3.146) 3. data analysis 3.1 model description and fitting procedure the available fitting data consists of measurements taken from trees located within different selected plots. least square method was used to fit data using the various candidate functions listed below. in this study, six crown-stump diameter equations were proposed as candidate models for the crown diameter prediction of p. biglobosain the study area. these equations are listed accordingly as follows: linear, single logarithm, double logarithm, power, growth and exponential. the candidate models are expressed as follows; 𝐶𝑑 = 𝑏0 + 𝑏1𝐷𝑠𝑡 (3) 𝐶𝑑 = 𝑏0 + 𝑏1𝑙𝑛𝐷𝑠𝑡 (4) 𝑙𝑛𝐶𝑑 = 𝑏0 + 𝑏1𝑙𝑛𝐷𝑠𝑡 (5) 𝐶𝑑 = 𝑏0𝐷𝑠𝑡 𝑏1 (6) 𝐶𝑑 = 𝑒(𝑏0+ 𝑏1𝐷𝑠𝑡) (7) 𝐶𝑑 = 𝑏0𝑒 ( 𝑏1𝐷𝑠𝑡) (8) where; cd = crown diameter, dst = stump diameter, b0 and b1 = regression parameter 3.2 model evaluation and validation the evaluation of the candidate models was based on graphical and numerical analysis of the residuals which are; least values of the standard error of estimate (see), prediction error sum of squares (press), akaike information criterion (aic) and adjusted coefficient of determination (adj.r2). they are mathematically expressed as follows: 𝐴𝑑𝑗. 𝑅2 = 1 − (1−𝑅2)(𝑛−1) 𝑛−𝑝 (9) 𝑆. 𝐸. 𝐸. = √ ∑( 𝑌𝑖−�̂�𝑖) 2 𝑛−𝑝 (10) 𝑃𝑅𝐸𝑆𝑆 = ∑ ([𝑌𝑖 −]�̂�(−𝑖) ∗ ) 2𝑛 𝑖=1 (11) 𝐴𝐼𝐶 = 𝑁ln(𝑅𝑆𝑆) + 2𝑝 (12) where; �̅�𝑖 = arithmetic mean of the observed value, 𝑌𝑖 = observed value of y for observation i �̂�𝑖= predicted value i, �̂�(−𝑖) ∗ = predicted value of y for observation i as calculated from a regression equation derived through fitting the p parameter model to data obtained by deleting observation i from the original data set, chukwu et al. /journal of tropical forestry and environment vol. 07, no. 01 (2017) 43-53 47 𝑛=the total number of observations 𝑌𝑖 (trees) used in fitting the model, 𝑝= the number of model fixed parameters, 𝑅𝑆𝑆 = residual sum of square. the overall best candidate model was validated using an independent data of about one-third of the data used for the model calibration and fitting. the t-test for paired samples was adopted as the validation method in this study. in all statistical analyses, a confidence level of p < 0.05 was used for statistical significance. 4. results 4.1 summary statistics for tree growth variables the data obtained from the field inventory were carefully organized and analysed in order to detect the underlying growth patterns. the data comprise of tree growth variables measured from nine sample plots of parkia biglobosa stand in the university of agriculture makurdi, benue state. a total of 265 trees were measured and summary statistics of the data used in this study are presented in figures (1 – 2) below. the mean values, standard deviation (sd) and standard error (se) of crown diameter and stump diameter are displayed in the box plots below (figures 1 – 2).the distribution of stump diameter (dst) ranged from 27.50 to 95.43 cm and crown diameter ranged from 2.90 to 11.55 m. table 1 shows the result of pearson’s product-moment correlation analysis between crown diameter (cd), diameter at breast height (dbh) and stump diameter (dst). the result revealed that dbh and dst are highly and positively correlated (r = 0.93). the result also shows that cd is highly and positively correlated with dst with r value of 0.84. this implies that cd increases with increase in dst. the graphical relation between the explanatory variable (dst) versus response variable (cd) is shown in figure 3. the pattern of the scatter plot (graph) showed that crown diameter of parkia biglobosa in the study area are essentially linearly related with stump diameter. mean = 42.7775 mean±se = (41.9467, 43.6084) mean±sd = (29.2526, 56.3025) dst 25 30 35 40 45 50 55 60 figure 1: box and whisker for summary statistics of tree stump diameter (dst) in cm. 48 mean = 6.4055 mean±se = (6.2914, 6.5195) mean±sd = (4.5485, 8.2624) cd 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5 figure 2: box and whisker for summary statistics of tree crown diameter (cd) in m. table 1: correlation analysis dst (cm) dbh (cm) cd (m) dst (cm) 1 dbh (cm) 0.93* 1 cd (m) 0.84* 0.84* 1 * correlation coefficient is significant at the 0.05 level (2 tailed), n = 265, cd = crown diameter (m), dbh = diameter at breast height (cm) and dst = stump diameter (cm) figure 3: relationship between crown diameter and stump diameter. y = 0.1159x + 1.4466 r² = 0.7129 0 2 4 6 8 10 12 14 0 20 40 60 80 100 120 c r o w n d ia m e te r ( m ) stump diameter (cm) chukwu et al. /journal of tropical forestry and environment vol. 07, no. 01 (2017) 43-53 49 4.2 crown diameter prediction models the crown diameter models developed in this study was to estimate the present and future values of crown diameter at individual tree level for parkia biglobosa within the university of agriculture, makurdi. the models were developed using individual tree stump diameter as independent variable and crown diameter as dependent variable. the models developed and tested (equations 3–8) were in linear, single logarithmic, double logarithmic, power and exponential functions. all parameters were found to be significant at the 5% level of probability. the models used for fitting data performed well and produced very similar results. on the basis of estimated 𝐴𝑑𝑗. 𝑅2 values, 65.1% to 71.2% of the total variation in observed crown diameter values was explained by stump diameter in the six candidate models. the individual tree models developed using stump diameter (dst) as independent variable (table 2) showed that power model has the highest value of 𝐴𝑑𝑗. 𝑅2(0.716) with see, press and aic values of 0.9897, 0.9897, 257.5322 and 2482.37 respectively. this was followed by linear and single logarithmic models with the same values of adj.r2 of 0.712 but with differences in the values of see, press and aic values (table 2). double logarithmic function (model 3) gave the least value of adj.r2 of 0.651with see, press and aic values of 0.1729, 262.9998 and 717.56 correspondingly. figure 4 shows the graph of the residuals distribution against the predicted natural logarithm of crown diameter. the equation 5 seems to uphold constant error variance assumption. 4.3 model validation table 3 shows the result of the validation of the best model (equation 5). the validation test shows that observed value was not significantly different from the predicted value of natural logarithm of crown diameter at probability level of 0.05. table 2: examined crown-stump diameter models model no function fit statistics adj.r2 see press aic 1 𝐶𝑑 = 1.447 + 0.116𝐷𝑠𝑡 0.712 0.9969 262.9999 1719.97 2 𝐶𝑑 = 11.227 + 5.398𝑙𝑛𝐷𝑠𝑡 0.712 0.9960 263.0001 1720.16 3 𝑙𝑛𝐶𝑑 = 2.542 + 0.814𝑙𝑛𝐷𝑠𝑡 0.651 0.1729 262.9998 717.56 4 𝐶𝑑 = 12.577×𝐷𝑠𝑡0.785 0.716 0.9897 257.5322 2482.37 5 𝐶𝑑 = 𝑒(1.201+1.487𝐷𝑠𝑡) 0.672 1.0644 297.9509 2481.44 6 𝐶𝑑 = 3.324×𝑒(1.487𝐷𝑠𝑡) 0.672 1.0644 297.9509 2481.44 50 figure 4: residual distribution against ln cd using double logarithmic model (equation 5). table 3: results of validation of model 3 using t test for paired sample variable mean sd se mean n diff t df p remark cd observed 6.5720 1.8220 0.1988 cd predicted 5.5533 0.2415 0.0264 84 0.0187 1.7414 83 0.3451 ns sd = standard deviation, standard error, diff = hypothesized mean difference, df = degree of freedom, p = probability value, ns = not significant at 0.05. 5. discussion in this study, information on the tree growth variables (dst and cd) was presented in figures 1and 2. before models development, correlation analysis was carried out to give an insight of the association between crown diameter and other tree growth variables. it was observed from the correlation matrix that crown diameter was highly correlated with stump diameter. that is, trees with larger diameter have wider crown diameters. this relationship is of adaptive significance to the trees because crown diameter contributes immensely to trees total weight. it was observed from graphical relationship that crown diameter showed a linear relationship with stump diameter. avery and burkhart (2002) stated that forest management decisions are predicated on information about current and future resource conditions. however, in this study effort was directed towards obtaining crown diameter prediction models at individual tree base using stump diameter. previous study by shamaki and akindele (2013) has proven that diameter at breast height (dbh) and stump diameter (dst) are highly correlated. hence, to avoid co-linearity between the two growth variables (dst and dbh) as indicated by huang et al. (2003), only stump was selected as independent variable for developing crown diameter models. the principle of using stump diameter alone was to help forest managers obtain information on the original crown structure of a forest after exploitation either by legal or illegal activities within the forest. estimating tree growth variables after exploitation can only be possibly done through the stumps (osho, 1983; shamaki and akindele, 2013). -0.4 -0.3 -0.2 -0.1 0 0.1 0.2 0.3 0.4 0 0.5 1 1.5 2 2.5 3 r e si d u a ls predicted chukwu et al. /journal of tropical forestry and environment vol. 07, no. 01 (2017) 43-53 51 the developed models using stump diameter as explanatory variable were in linear, single logarithmic, double logarithmic, power, and exponential functions form (equations 3 – 8).the models used for fitting data performed well and produced very similar results. all parameters were found to be significant at the 5% level of probability.on the basis of estimated 𝐴𝑑𝑗. 𝑅2 values; 65.1% to 71.2% of the total variation in observed crown diameter values was explained by stump diameter in the candidate models. the criteria adopted for ranking the models was through comparison of adj.r2, see, press and aic which are standard ways of verifying models predictive ability as pointed out by li et al. (2002), huang et al. (2003), shamaki and akindele (2013) and adesoye and ezenwenyi (2015). from the results of model evaluation criteria, out of the six candidate models showed that equation 5 (double logarithmic function) ranked the first, with the least values of; see, press and aic. comparable results were reported by shamaki and akindele (2013) as in the case of merchantable volume and stump diameter relationship and adesoye and ezenwenyi (2015); using dbh to predict crown diameter. this reveals that stump diameter can play a similar role to dbh as a good predictor of crown diameter. this result is not similar to the findings of avsar and ayyildiz (2005) who observed that crown diameter-dbh relationships can be described by power model. though, his report was on crown diameter and dbh which can be used interchangeably with stump diameter. in this study power model was found to be inappropriate. the double logarithmic function (model 3) was chosen as the best fitted model, although it has the least value of adjusted r2. however, other functions (including power model) had higher value of adjusted r2 but they also displayed relatively higher values of estimation errors (see, press and aic) which are not good predictor of best models. therefore, all the evaluation criteria (adj.r2, see, press and aic) were considered in ranking and subsequent selection of the models. the higher the adjusted r2 values the better and the lower the see, press and aic the better the model. the efficiency of this procedure was confirmed by akindele (1985) and odunlami (1992). hence, additional data from independent plots were used to validate the model. the paired ttest was used to test for significance between predicted and the observed crown diameters. the result showed a non-significant difference. this indicates that the developed crown-stump diameter equation is valid for estimation of p. biglobosa stands in makurdi, benue state. furthermore, figure 4 shows the distribution of residuals against the predicted natural logarithm of crown diameter and constant error variance assumption appears to be upheld by this double logarithm model (equation 5). 6. conclusions predicting tree growth characteristics for stump diameter can aid the reconstruction of sizes of removed trees. these includes; reviewing harvesting practices, assessing damage due to catastrophic events, creating historical records of past management activities, and establishing loss due to timber trespass. hence, stump diameter was therefore, used as the only independent variable owing to its strong correlation with dbh as asserted by this study. thus, both dbh and dst can be used interchangeably. this study further concluded that, the crown diameter can be more accurately and precisely predicted from stump diameter using the double logarithmic function (equation 5). this model is therefore, recommended for the forest managers and the management of the university of agriculture makurdi as a research tool and a good estimator of crown diameter in an event of both legal and illegal felling. it should be noted that the models developed by this study were based on data collected in university of agriculture makurdi, benue state catchment region and covered a limited range of 52 stump and crown diameters. the models should therefore, be used with caution outside this region. further studies need to be done to test applicability of these models across similar ecological zones and to relate the growth rates/patterns in both stump and crown diameters of open grown tree species to the fitted models. reference adesoye, p.o. and ezenwenyi, j.u. 2015. crown diameter prediction models for tectonagrandislinn.finomo forest reserve, nigeria, journal of forestry research and management. vol.11, 72-87; 2014. issn: 0189-8418 akindele, s.o., 1985. the development of various linear volume equations for teak in gambari forest reserve. unpublished b.sc. project. university of ibadan, nigeria. 72p. akindele, s.o., 2003. volume prediction from stump diameters of gmelinaarborea(roxb) trees in akure forest reserve, nigeria. nigerian journal of forestry, vol. 33 (2): 116 – 123. alabi, d.a., akinsulire, o.r. and sanyaolu, m.a., 2005. african journal of biotechnol; vol. 4; pp. 812-815. avsar m. d and v. ayyildiz (2005): the relationships between diameter at breastheight, tree height and crown diameter in lebanon cedar(cedruslibania.rich.) of the yavsan mountain, kahramanmaras, turkey.pakistan journal of biological sciences 8 (9), 1228-1232p. corral-rivas, j.j., barrio-anta, m., aguirre-calderon, o.a. and dieguez-aranda. u., 2007. use of stump diameter to estimate diameter at breastheight and tree volume for major pine species in el salto durango (mexico). forestry80:29–40. dubravac, t., dekanic j., vrbek b., matosevic, d., roth v., jakovljevic, t. and zlatanov, t., 2009. crown volume in forest stands of pedunculate oak and common hornbeam. periodicumbiologorum111(4), 479-485. elly, n.s. and joseph, c., 2012. parkiabiglobosa: a pot ential multipurpose fodder tree legume in west africa. international tree crops journal; volume 7, issue 1992; published online: 05 apr 2012; doi: 10.1080/01435698.1992.9752911; pages 113-139 foli, e.g., alder, d., miller, h.g. and swaine, m.d., 2003. modeling growing space requirements for some tropical forest tree species; forest ecology and management 173 (2003); pp. 7988 gering, l.r. and may, d.m., 1995. the relationship of diameter at breast height and crown diameter for four species groups in hardin county, tennessee. south. journal of applied forestry 19:177-181. gyang, e.o., 1997. students information handbook (1996-1998). university of agriculture, makurdi. p. 1-3. hemery, g.e., savill p.s., and pryor s.n., 2005. applications of the crown diameter stem diameter relationship for different species of broadleaved trees. forest ecol. manage., 215(3): 285-294. husch b., beers, t.w. and kershaw jr. j.a., 2003. forest mensuration4th edition. new jersey: john wiley and sons inc. 443pp. husch, b., miller c.i. and beers, t.w., 1982. forest measurement. john wiley & sons, new york, usa. hutchinson, j., and dalziel, j.m., 1963. flora of west tropical africa. crown agents, london, 6 vols. kigomo, b.n., 1991. crown and bole diameter relationship in brachyleanahuillensisand its application to silvicultural interventions. e. afr. agric. forest. j., 57(1): 67-73. kigomo, b.n., 1998. morphological and growth characteristics in brachyleanahuillensis(muhugu); some management considerations. kenya j. sci. (series b), 11(1-2): 11-20. kozlowski t., kramer p., pallardy s., 1991. the physiological ecology of woody plants. academic press, new york. chukwu et al. /journal of tropical forestry and environment vol. 07, no. 01 (2017) 43-53 53 krajicek j.e., brinkman, k.a and gringrich s.f., 1961. crown competition a measure of density. forest science 7: 35–42. li b., morris, j. and martin, e.b., 2002. model selection for partial least squares regression, chemometrics and intelligent laboratory systems 64, 79– 89 lockhart, b.r., robert, c., weih j.r. and keith, m.s., 2005. crown radius and diameter at breast height relationships for six bottomland hardwood species. j. arkansas acad. sci., 59: 110-115. ntui, v.o., uyoh, e.a., urua, i.s., ogbu, u., and okpako, e.c., 2012. regeneration of parkiabiglobosabenth.: an important tree species of africa. journal of microbiology and biotechnology research, 2(1), 169-177; the scholar's research library database; issn: 2231 – 3168. odunlami b.a., 1992. development of volume equations for gmelinaarboreaplantation in oluwa forest reserve. unpublished b. agric (teh) project fut akure. 66p osho, j.s.a., 1983. volume prediction from stump diameter for teak (tectonagrandisl.f.) in onigambari forest reserve. nigerian journal of forestry 13 (1&2): 53-56. özçelík r., brooks j.r., diamantopoulou, m.j. and wiant-jr, h.v., 2010. estimating breast heght diameter and volume from stump diameter for three economically important species in turkey, scandinavian journal of forest research, vol. 25,iss. 1, http://dx.doi.org/10.1080/02827580903280053 popoolaf.s.andadesoye p.o., 2012. crown ratio models for tectonagrandis(linn. f) stands in osho forest reserve, oyo state, nigeria journal of forest science, issn 2287-2396, vol. 28, no. 2, pp. 63-67, shamaki, s.b. and akindele, s.o., 2013. volume estimation models from stump diameter for teak (tectonagrandislinn f.) plantation in nimbia forest reserve, nigeria, journal of environmental science and water resources, issn 2277 0704, vol. 2(3), pp. 089 094 teklehaimanot, z. 2004. exploiting the potential of indigenous agroforestry trees: parkiabiglobosa and vitellariaparadoxa in sub-saharan africa.agroforestry systems, 61, 207-220 westfall, j.a., 2010. new models for predicting diameter at breast height from stump dimensions, north. j. appl. for. 27(1) zuhaidi, y.a., 2009. local growth model in modeling the crown diameter of plantation-grown dryobalanops aromatic; journal of tropical forest science 21(1); pp.66-71. microsoft word 6 assessment of hazardous volatile organic compounds mohan & ethirajan /journal of tropical forestry and environment vol. 2, no. 01 (2012) 48-59 48 assessment of hazardous volatile organic compounds (voc) in a residential area abutting a large petrochemical complex s. mohan 1 , r. ethirajan* 1 , 1 department of civil engineering, indian institute of technology, madras, chennai 600036, india date received: 27-09-2011 date accepted: 22-02-2012 abstract the results of voc monitoring in a residential area abutting a petrochemical complex and the influence of causative parameters on the concentration is discussed in this paper. the monitored data reveals that about 21 hazardous voc are predominantly present in the study area. toluene is the most abundant compound of all. the mean concentration of benzene, a known carcinogen, is 38 µg/m 3 . the wide variation in toluene to benzene ratio (t/b) and the weak correlation between the concentration of various compounds and nox indicate that they are contributed by multiple sources. there is no fixed pattern observed in the concentration variation between morning and evening samples. the btex ratio observed in this study varies from 1:2.6:0.3:0.2 to 1:9.5; 2.1:1.4. the study reveals that the hazardous voc in the study area are contributed by multiple sources and that the concentration of some of them is very high. keywords: hazardous voc, petroleum refinery, btex ratio, multiple sources, meteorology, open burning 1. introduction the volatile organic compounds (voc) in the atmosphere can be broadly classified into two types; one that is having significant direct risk to human health and ecosystem and the other that take part in the complex photochemical reaction leading to the formation of high amounts of troposphere ozone, peroxyacyl nitrates (pan) and other oxidants in urban areas (colbeck and mackenzie, 1994; brown et al., 2007; liu et al., 2008; wang and zhao, 2008; parra et al., 2009). petroleum refineries, petrochemical industries, automobiles, combustion of fossil fuels and biomass, use of solvents and marketing of petroleum products are major sources of voc in urban environment (jorquera and rappengluck, 2004; kansal, 2009). many earlier studies reported that the voc emission from petroleum refineries and petrochemical industries are hazardous in nature and pose serious risk to human health and that these industries heavily influence the concentration of ambient voc in the vicinity (badol et al., 2008; nguyen et al., 2009). comprehensive monitoring of ambient voc to quantify their ambient concentrations, to identify their emission sources and to assess contribution levels of various sources is essential for developing strategies for management of voc (environment australia, 2006; wang and zhao, 2008). these studies had also assessed the benzene, toluene, ethylbenzene and xylene (btex) ratios and toluene to benzene (t/b) ratio and used them to assess the contributing sources. * corresponding author: e-mail-rnethirajan@gmail.com tel-++ 91 9444119155, fax++ 94 11 25672540 issn 2235-9370 print / issn 2235-9362 online ©2012 university of sri jayewardenepura mohan & ethirajan /journal of tropical forestry and environment vol. 2, no. 01 (2012) 48-59 49 studies had also monitored the diurnal and seasonal variations of the concentration of various compounds. quantity of highly reactive species usually decrease in daylight time due to photochemical reactions, but the quantity of relatively less reactive species gradually increases due to accumulation. wang and zhao (2008) assessed ambient volatile organic compounds near major roads in urban nanjing, china and found that the toluene-to-benzene ratios were 4.4 and 3.8 in the first and the second sampling campaign, respectively. liu et al. (2008), while monitoring the ambient voc in an industrial city of southern taiwan found that toluene, isopentane, ethylbenzene, and benzene were the most abundant species with high t/b ratios (7.56 – 14.25) and concluded that the higher ratio was due to impact from industries and mobile emissions. it was also observed in this study that the small x/b and x/e (0.38–0.65) both revealed the fact that photochemical reactions were active. in urban areas, especially in cities where petroleum refineries and petrochemical industries are located, a large population of people are exposed to high levels of toxic and hazardous voc. poverty and improper town planning force a large number of people to live close to the potential sources like petrochemical complexes. regular monitoring of hazardous voc in the ambient air is not carried out in many countries. hence, there is no or very limited information is available on the prevailing concentration of predominant hazardous voc in the atmosphere. even with the available information, the enforcing agencies are struggling hard to evolve strategies for the management of these voc due to difficulties in identifying contributing sources and their contribution levels. in countries like india this problem is more complex as profiles of voc emission from various potential contributing sources are also not available. the main objective of the reported work was to assess the levels of hazardous voc present in the typical identified area and to establish a relationship between their concentration and their causative parameters. this paper discusses the results of monitoring of hazardous voc at manali near chennai, a south indian metropolitan city, where a large petrochemical industrial complex is located. the identification of predominantly present compounds and their concentration variation with respect to possible influencing parameters are the major aspects discussed in this paper. 2. study area 2.1 geographical details chennai is the fourth largest city in india located on its east coast. the total area of the city is 174 km2. a 13 km long beach, the second longest beach in the world is one of the significant features of the city. a petrochemical industrial complex is located on its outskirt on the northern side at a place called manali. this complex has a major petroleum refinery, surrounded by more than 15 large scale petrochemical industries. the emissions from these industries affect the quality of ambient air in the city. in addition to these industries there are about 25 lakh vehicle plying on the chennai roads every day. chennai corporation is dumping more than 50% (about 1500 t/d) of the total unsegregated solid wastes generated in the city in a huge area at kodungaiyur near manali industrial complex. the municipal solid waste dumping yard of manali municipality lies in between these large petrochemical industries. open burning of solid wastes takes place round the clock in all these dump yards resulting in contribution of several hazardous air pollutants to the ambient air. in addition to these sources, there are large scale sewage and industrial effluent treatment plants located in and around this area. thus, it can be seen that this location is highly susceptible to the exposure of various hazardous air pollutants. the location of the study area is shown in figure 1. 2.2 meteorological details the mean winter temperature of chennai is 30 oc and the mean summer temperature is 35 o c. the maximum ambient temperature is as high as 43 o c during hottest months of april and may. october to december is the monsoon period with average rainfall of 1100 mm/year. the wind pattern in chennai mohan & ethirajan /journal of tropical forestry and environment vol. 2, no. 01 (2012) 48-59 50 is unique. south-west winds are predominant for about 7 months in a year between march and september. the north-east winds are common during october to february. however, being a coastal city there is a major diurnal variation in wind direction and wind speed in chennai. even during southwest wind season a substantial part of the day may experience easterly or north-easterly winds. figure 1: manali petrochemical industrial complex 2.3 contributing sources voc are contributed by almost all the sources of air pollution. petroleum refineries and petrochemical industries are the major sources of voc in the areas where these industries are located (liu et al., 2008; wang and zhao, 2008; parra et al., 2009). several studies reveal that automobiles are significant contributors in non-industrialized urban areas (nguyen et al., 2009; parra et al., 2009). sampling location petrochemical industries tiruvottiyur solid waste dump yard refinery manali solid waste dump yard kodungaiyur solid waste dump yard mohan & ethirajan /journal of tropical forestry and environment vol. 2, no. 01 (2012) 48-59 51 kansal (2009) reported that biomass burning contributes to about 45 % of the total voc emitted by anthropogenic sources on the earth. wastewater treatment plants also emit large amount of voc (cheng et al., 2008). hence, a detailed assessment of various emission sources of voc in the selected study area was carried out. the significant industrial sources that were identified are listed in table 1. the details about other significant sources such as automobiles, open burning of un-segregated garbage and biomass, waste disposal sites, fuel distribution centers were also collected. it was identified from this assessment that the following five major source types are contributing to the ambient voc concentration in the study area; petroleum refinery, petrochemical industries, sewage and industrial wastewater treatment plants, open dumping and burning of solid wastes and automobiles. table1: details of significant industrial sources of voc at manali sl no type of industry raw materials product 1 2 3 petroleum refinery – 1 no fertilizer industry –2 nos. petrochemical industries – 13 nos. crude oil naphtha phosphoric acid potash propylene, chlorine, lime, kerosene, benzene, methanol, terepthalic acid, mono ethylene glycol, mono propylene glycol, pure isopthalic acid, alkyl phenol, sulphur, naphthalene, sulphuric acid, formaldehyde, caprolactum, lpg, aluminum trichloride, epichlorohydrin, bisphenol-a, sodium hydroxide, hydro choleric acid, polyamides. petroleum products like lpg, naphtha, ms, diesel, sko, lube oil, wax, hexane, fo urea npk epichlorohydrin, linear alkyl benzene, propylene oxide, propylene glycol, polyol, polyester, pet, lube oil additives, syntan, synthetic fat liquor, grease & lubricants, nylon tyre card fabric & yarn, poly butylenes, epoxy resin, methyl ethyl ketone 2.4 sampling and analysis as monitoring and assessment of the ambient concentration of various hazardous voc present in the study area had not been done prior to this study, it was monitored as a part of this study. manali police station situated at manali residential area was identified as sampling location. all samples were collected from this location. the sampling and analysis were carried out as per the procedures laid down in us epa compendium method to-17 (us epa, 1997). as the study area is dominated by industrial sources, emphasis was given to the assessment of voc that are more hazardous. the ambient air samples were collected in standard adsorption tubes of marks international ltd with 3.67 mm id and 128.02 mm length. the tube contains tenex and carbopack b in the ratio of 125 mg to 75 mg. the skc make low volume sampler (model no. skc/224/pcxr8) was used to draw air through these adsorption tubes (kuntasal et al., 2005; ras et al., 2008). most of the samples were collected with an air flow rate of about 84 ml/min for two hours resulting in collection of pollutants from about 10 l of air (borrego et al., 2006, hellen et al., 2006). however, simultaneous samples were also collected with different flow rates and for different durations to assess the influence of these parameters in sampling. samples were collected between 8 a.m. and 10 a.m. in the morning and 4 p.m. and 6 p.m. in the evening as per this protocol (hellen et al., 2003). some samples were also collected in the night between 10 p.m. and 12 midnight. a total of 50 samples (23 samples during weekdays and 27 samples during weekends/holidays) were collected between july 2008 and october 2009. the sample tubes were thermally desorbed to release the pollutants and the pollutants were analysed in gc-ms. mohan & ethirajan /journal of tropical forestry and environment vol. 2, no. 01 (2012) 48-59 52 the adsorption tubes were desorbed at 250 o c for 10 min. the pollutants from the thermal desorption were collected in a secondary trap at 10 o c. the secondary trap was then rapidly heated to 300 o c to release all the pollutants to the gc column. a column of 60 m length, 0.25 mm id and 4 micron thickness solid coating of varian make was used. ms detector (scan mode) of agilent technologies make (model no. 6890n/5973inat) was used to detect and quantify the pollutants (parra et al., 2009). the initial temperature of the column was 35 o c for 3 min. the temperature of the column was raised at the rate of 8 o c/min up to 90 o c. after 2 min at 90 o c, the temperature was raised at the rate of 6 o c/min to 240 o c. the total run time of the sample was 40 min (harrison and roger 1986; ribes et al., 2007). all the detected compounds were identified using nift library. compounds listed under 60 target compound list of us epa were quantified using appropriate standard. 3. results and discussion 3.1 compounds and concentrations several studies have reported that hundreds of different compounds were detected when monitoring voc in urban areas (wang and zhao, 2008; nguyen et al., 2009). in this study, about 40 different volatile organic compounds were detected in all the samples that were analysed and more than 100 different compounds were detected in some of the samples. out of these compounds, the compounds that are listed under 60 target compound list of us epa were quantified using appropriate standard. among these 60 compounds, about 21 hazardous volatile organic compounds were predominantly present in all the samples. the maximum, minimum and mean concentrations of all these 21 compounds are listed in table 2. table 2: observed concentrations of different voc si. no compounds concentration in µg/m 3 maximum minimum mean 1 benzene 83.25 13.24 38.23 2 toluene 352.58 49.87 156.14 3 ethylbenzene 61.40 5.43 27.37 4 m,p-xylene 59.52 3.97 26.80 5 o-xylene 54.52 2.29 22.94 6 1,2-dichloropropane 59.16 0.00 13.71 7 trichloroethylene 13.65 0.10 4.59 8 styrene 22.00 1.00 6.31 9 1,3,5-trimethylbenzene 27.20 0.41 7.22 10 1,2,4-trimethylbenzene 12.25 0.42 4.67 11 naphthalene 23.56 0.43 7.04 12 isopropylbenzene 5.27 0.00 1.31 13 n-propylbenzene 9.51 0.10 2.97 14 carbon tetrachloride 23.96 0.00 7.75 15 1,4-dichlorobenzene 18.35 0.00 4.33 16 secbutylbenzene 3.32 0.00 0.34 17 4-isopropyltolune 13.17 0.00 1.76 18 butylbenzene 6.32 0.00 0.42 19 chloroform 19.01 0.00 20.21 20 1,2-dichloroethane 84.16 0.00 9.50 21 trichlorofluoromethane 0.92 0.00 0.04 mohan & ethirajan /journal of tropical forestry and environment vol. 2, no. 01 (2012) 48-59 53 toluene is the most abundant compound of all with concentration ranging from 50µg/m 3 to 350 µg/m 3 . concentration of toluene observed in similar studies were not so high as observed in this study even though toluene was also found to be most abundant compound in all the studies (guo et al., 2004; nguyen et al., 2009). world health organization (who) recommended a maximum of 260µg/m 3 of toluene averaged over a week as a limiting value or the protection of human health from toluene (parra et al., 2009). the toluene concentration in about 10% of samples exceeds 260µg/m 3 . the mean concentration of benzene, a known carcinogen (who, 2000) is 38µg/m 3 . benzene is the only voc for which standard has been prescribed in the new national ambient air quality standards of india as 5µg/m 3 . benzene concentration exceeds this level in almost all the samples (figure 2). the mean concentration of 1,2-dichloroethane, 1,4-dichlorobenzene, trichloroethylene, and chloroform is also high and not many monitoring studies had identified such a high concentration of halogenated voc in the ambient air (fernandez et al., 2004; nguyen et al., 2009; parra et al., 2009). figure 2: variation of benzene concentration among different samples. the analysis of variation in the concentration of pollutants in different samples indicates that there is no common trend between all the pollutants. however, a strong correlation exists between the concentrations of certain specific compounds. benzene, toluene, ethylbenzene, m,p-xylene and o-xylene are strongly correlated with coefficients ranging between 0.70 and 0.90 similar to what was observed by fernandez et al., (2004) and buczynska et al. (2009). the concentrations of isopropylbenzene and npropylbenzene are also very well correlated with correlation coefficients of 0.8. the variation in the concentration of carbon tetrachloride and trichloroethylene follow a common trend with correlation coefficient of 0.70. naphthalene, 1, 2-dichloropropane, 1, 3, 5-trimethylbenzene are not having significant correlation with other compounds. it has been attempted to find if there is any correlation between the concentration of these compounds and nox. it was found that nox is not having any significant correlation with any of these compounds. previous studies have indicated that there will be strong correlation between vocs and nox only when automobile is the major contributor (fernandez et al., 2004; lung et al., 2007; parra et al., 2009). the above observations indicate that multiple source types are contributing to the concentration of these pollutants and that each source type contributes significantly to certain specific group of compounds. the study also reveals that automobile is not the major contributor of all the compounds. 0 10 20 30 40 50 60 70 80 90 1 7 13 19 25 31 37 43 49 c o n c e n tr a ti o n i n µ g / m 3 sample number measured concentration mean concentration std. deviation mohan & ethirajan /journal of tropical forestry and environment vol. 2, no. 01 (2012) 48-59 54 3.2 concentration variation between weekdays and weekends it has been attempted to find whether there is any distinct difference in the concentration of any of the compounds between weekdays and weekends. the mean concentrations of various pollutants on weekdays and weekends are given in table 3. the variation in the concentration of most of the compounds between weekdays and weekends is negligible. it clearly indicates that the emission of these compounds from most of the contributing sources is independent of the day of the week. the concentrations of ethylbenzene, m,p-xylene, and o-xylene are marginally higher on weekdays, which indicates that the automobile is one of the major contributors of these compounds (lee et al., 2002; fernandez et al., 2004). the higher concentration of some of the chlorinated compounds lime trichloroethylene, chloroform, 1, 2-dichloroethane etc. on weekends indicates the possibility of higher emissions from industries and commercial establishments due to maintenance and cleaning and also due to disturbance in power supply. table 3: mean concentration of various compounds on weekdays and weekends compounds concentration in µg/m 3 weekday weekend benzene 38.45 37.96 toluene 151.94 161.07 ethylbenzene 24.47 30.78 m,p-xylene 25.70 28.09 o-xylene 22.17 23.85 1,2-dichloropropane 14.76 12.48 trichloroethylene 4.61 4.56 styrene 6.25 6.39 1,3,5-trimethylbenzene 7.50 6.89 1,2,4-trimethylbenzene 4.12 5.32 naphthalene 6.98 7.11 isopropylbenzene 1.38 1.23 n-propylbenzene 2.73 3.25 carbon tetrachloride 8.33 7.07 1,4-dichlorobenzene 3.93 4.79 sec-butylbenzene 0.36 0.30 4,isopropyltolune 1.90 1.60 butylbenzene 0.50 0.32 chloroform 21.48 18.72 1,2-dichloroetahne 13.29 5.04 trichlorofluoromethane 0.06 0.01 3.3 diurnal variation in concentration there are certain contradictory observations made in different studies about the diurnal variation in the concentration. parra et al. (2009) observed that the concentration of voc is higher during morning compared to other times of the day, whereas nguyen et al. (2009) observed that the concentration peaks occurred only during afternoon. song et al., (2008) observed that the total voc concentrations were higher at night than at day in beijing due to stronger winds at day time. parra et al. (2009) also observed that the voc concentration during winter and autumn is higher due to atmospheric stability. the variation in the morning and evening concentration of the compounds is presented in table 4. it can be seen from the table 4 that the difference between the concentration of most of the compounds in the morning and evening samples is very less. the absence of fixed pattern in the mohan & ethirajan /journal of tropical forestry and environment vol. 2, no. 01 (2012) 48-59 55 concentration variation between morning and evening samples may be due to limited diurnal variation in the ambient temperature and due to dominance of emission from industries other contributing sources which operate round the clock. the minor variations, therefore, are mainly attributed to the wind direction and wind speed. similar observation was also reported by choi and ehrman (2004) when they investigated the source of volatile organic carbon in the baltimore, usa. table 4: mean concentration of various compounds during morning and evening compounds concentration in µg/m 3 morning evening benzene 41.71 36.44 toluene 153.50 161.28 ethylbenzene 30.22 25.04 m,p-xylene 27.70 26.22 o-xylene 23.78 22.56 1,2-dichloropropane 15.10 13.65 trichloroethylene 4.63 4.68 styrene 6.48 6.27 1,3,5-trimethylbenzene 8.22 6.69 1,2,4-trimethylbenzene 5.20 4.35 naphthalene 7.93 6.33 isopropylbenzene 1.41 1.30 n-propylbenzene 3.23 2.91 carbon tetrachloride 6.97 8.42 1,4-dichlorobenzene 3.85 5.15 sec-butylbenzene 0.36 0.26 4,isopropyltolune 1.42 2.37 butylbenzene 0.44 0.48 chloroform 16.85 21.20 1,2-dichloroetahne 9.50 10.60 trichlorofluoromethane 0.07 0.02 3.4 btex ratios ratios between the concentrations of benzene, toluene, ethylbenzene and xylenes (btex ratio) are very important and useful information to infer the sources of ambient concentration of various vocs. several studies concluded about the number and type of contributing sources using toluene to benzene ratio (t/b). higher t/b ratios indicate the presence of several contributing sources. the t/e, b/e and x/e ratios are useful tool to understand the photochemical age of the vocs. however, there exists a vast variation between btex ratios observed in different studies. lee et al., (2002) observed in his study that btex ratio could vary from 3:4:1:4 to 3:14:1:28. at locations where automobile is the only major contributing source, the toluene to benzene ratio (t/b) will be low, varying between 2 and 4. the t/b ratio however could be as high as 40 at locations where several source types contribute these compounds (lee et al., 2002; buczynska et al., 2009). the btex ratio observed in this study varies from 1:2.6:0.3:0.2 to 1:9.5:2.1:1.4. the toluene to benzene ratio (t/b) varies widely between 2.6 and 9.5. this clearly indicates that there are multiple contributing sources to these compounds in the identified area. the mean t/b ratio is about 4.5 on both holidays on working days (lee et al., 2002). the scatter plots between toluene/ethylbenzene (t/e) and toluene/m,p-xylene (t/x) is shown in figure 3. similarly the scatter plot between benzene/ethylbenzene (b/e) and benzene/m,p-xylene (b/x) is shown in figure 4. the higher r2 value of the plot in figure 3 than of the plot in figure 4 indicates that toluene, ethylbenzene and xylenes are contributed by the same mohan & ethirajan /journal of tropical forestry and environment vol. 2, no. 01 (2012) 48-59 56 source and that their emission levels are uniform with respect to each other whereas vast variation exists in the emission level of benzene. figure 3: scatter plot of t/e vs t/x figure 4: scatter plot of b/e vs b/x the variations of toluene to ethylbenzene (t/e), benzene to ethylbenzene (b/e) and m,p-xylene to ethylbenzene (x/e) ratios between summer and winter samples are shown in figure 5. ethylbenzene and xylene are more reactive than benzene and toluene and hence their concentration decreases quickly in the ambient air when the photochemical reaction takes place. the rate of photochemical reaction is higher in summer than in winter. it can be seen from figure 5 that both t/e and b/e ratios are high in summer than in winter. there is very little variation in x/e ratio between summer and winter. it indicates that the rate of photochemical reaction which reduces the concentration of ethylbenzene and m,p-xylene faster than the concentration of toluene and benzene is high in the area (parra et al., 2009). figure 5: variation of b/e, t/e and x/e ratios for summer and winter seasons 3.5 wind direction and concentration wind direction and wind speed play an important role in the concentration of various pollutants (choi and ehrman 2004). to analyse the variation in concentration with respect to wind direction, the samples were grouped under three categories. the first one is a set of samples collected during wind direction between south-east and north-east (se-ne), the direction in which most of the industries is located, including the refinery. out 50 samples, 15 samples were collected during this wind direction. the second group contains samples collected during wind direction between south-west and south-east (sw-se) and the third during wind direction between north and north-east (n-ne). sw-se direction is (b) t/e and x/e (a) b/e and x/e mohan & ethirajan /journal of tropical forestry and environment vol. 2, no. 01 (2012) 48-59 57 marked by a mixed type of activities including industrial, commercial and residential and 22 samples were collected during this wind direction. there are only a few industries located in n-ne direction and 3 samples were collected during this period. the wind was calm while collecting 10 samples. the mean concentration of all the compounds in the samples under each of these groups has been compared to find out the pollutants that are predominant during different wind directions and presented in table 5. table 5: mean concentration of compounds during different wind directions compounds concentration in µg/m 3 sl. no. wind direction calm n-ne sw-se se-ne 1 benzene 37.53 40.10 36.18 37.46 2 toluene 180.48 154.69 152.29 154.05 3 ethylbenzene 28.22 27.52 26.81 28.97 4 m,p-xylene 26.47 27.09 27.58 24.83 5 o-xylene 25.78 24.18 22.03 21.61 6 1,2-dichloropropane 15.13 13.02 13.02 15.30 7 trichloroethylene 5.69 4.62 3.63 5.75 8 styrene 8.95 5.86 6.54 7.86 9 1,3,5-trimethylbenzene 7.40 6.36 7.02 9.30 10 1,2,4-trimethylbenzene 4.41 6.14 4.68 3.49 11 naphthalene 5.47 6.55 6.63 10.99 12 isopropylbenzene 2.65 0.98 1.41 1.51 13 n-propylbenzene 4.19 3.24 2.81 2.97 14 carbon tetrachloride 10.92 8.12 6.99 8.63 15 1,4-dichlorobenzene 6.09 4.48 3.15 6.58 16 secbutylbenzene 0.14 0.26 0.15 0.59 17 4isopropyltolune 0.92 1.82 2.18 1.93 18 butylbenzene 0.43 0.66 0.54 0.09 19 chloroform 15.38 21.88 21.26 30.74 20 12dichloroetahne 7.98 11.05 6.51 11.60 21 trichlorofluoromethane 0.31 0.01 0.03 0.03 the mean concentration of benzene is higher during sw-se winds, whereas the mean concentration of toluene is higher during n-ne winds. the mean concentration of both these compounds in the other three directions is almost the same. significant presence of halogenated voc during se-ne winds, the direction in which sea is located indicates that sea is one of the sources of emission of certain halogenated voc (srivastava 2004). continuous burning of solid waste at manali solid waste dump yard, which is located very close to the sampling point could be the reason for higher concentration of naphthalene during calm condition. except these minor variations, the mean concentration of most of the compounds are the same in all the wind directions indicating equal contribution from multiple contributing sources to the concentration of these compounds. it also indicates that refinery alone is not the major contributor of these compounds. 4. conclusions the study revealed that the concentration of some of the hazardous voc are very high, high enough to cause significant health effects to the people living in the vicinity of this industrial complex. the higher t/b ratio clearly indicates that there are multiple sources contributing to the concentration of hazardous voc in the study area. though automobile is one of the contributors of these pollutants, the study revealed that the refinery and the petrochemical industries are major and significant contributors of many compounds. the study also revealed that some of the compounds are contributed by long mohan & ethirajan /journal of tropical forestry and environment vol. 2, no. 01 (2012) 48-59 58 distance sources. the vast differences in the concentration levels over the study duration suggest that there is no fixed pattern in the emission of these compounds. high correlation between the concentrations of certain compounds clearly indicates that they are emitted by distinct source types. the wind speed and wind direction are major factors in determining the concentration levels while the ambient temperature plays very less role as it is almost constant over the day and throughout the year. the major limitation of this study is its inability to identify the actual contributors and their contribution levels for each sample. as multiple sources are contributing, specific contributing sources and their exact contribution levels for various compounds in each sample have to be assessed using a suitable receptor model so as to develop strategies to manage the voc level in this area. references badol, c., locage, n., leonardis, t. and galloo, j.c., 2008. using a source-receptor approach to characterise voc behavior in a french urban area influenced by industrial emissions. part i: study area description, data set acquisition and qualitative data analysis of the data set. science of the total environment. 385: 441-452. borrego, c., gomes, p., barros, n. and miranda, a.i., 2006. importance of handling organic atmospheric pollutants for assessing air quality. journal of chromatography a. 889: 271-279. brown, s.g., frankel, a. and hafner, h.r., 2007. source apportionment of vocs in los angeles area using positive matrix factorization. atmospheric environment. 41: 227-237. buczynska, a.j., krata, a., stranger, m., godoi, a.f.l., kontozova-deutsch, v., bencs l., naveau, i., roekens, e. and van g.r., 2009. atmospheric btex-concentrations in an area with intensive street traffic. atmospheric environment. 43: 311–318. cheng, w.h., hsu, s.k. and chou, m.s., 2008. volatile organic compound emissions from wastewater treatment plants in taiwan: legal regulations and cost control. journal of environmental management. 88: 1485-1494. choi, y.j. and ehrman, s.h., 2004. investigation of sources of volatile organic carbon in the baltimore area using highly time-resolved measurements. atmospheric environment. 38: 775-791. colbeck, i. and mackenzie, a.r., 1994. air pollution by photochemical oxidants, elsvier, amsterdam, the netherlands. environment australia, 2000. state of knowledge report: air toxics and indoor air quality in australia, air toxics section, canberra. fernandez, v.v., lopez, m.p., muniategu, s., prada, r.d., fernandez, f.e. and tomas, x., 2004. c1 to c9 volatile organic compound measurements in urban air. science of the total environment. 334335: 167-176. guo, h., wang, t., simpson, i.j., blabe, d.r., yu, x.m. and kwok, y.h., 2004. source contributions to ambient vocs and co at a rural site in eastern china. atmospheric environment. 38: 4551-4560. harrison, r. and roger, p., 1986. hand book of air pollution analysis, chapman & hall, new york, usa. hellen, h., hakola h. and laurila, t., 2003. determination of source contributions of nmhcs in helsinki (60 o n, 25 o e) using chemical mass balance and the unmix multivariate receptor models. atmospheric environment. 37: 1413-1424. hellen, h., hakola, h., pirjola, l., laurila, t. and pystynen, k.a., 2006. ambient air concentrations, source profiles and source apportionment of 71different c2 c10 volatile organic compounds in urban and residential areas of finland. environ sci technol. 40: 103-108. jorquera, h. and rappengluck, b., 2004. receptor modeling of ambient voc at santiago, chile. atmospheric environment. 38: 4243-4263. kansal, a., 2009. sources and reactivity of nmhcs and vocs in the atmosphere: a review. journal of hazardous materials. article in press. mohan & ethirajan /journal of tropical forestry and environment vol. 2, no. 01 (2012) 48-59 59 kuntasal, o.o., karman, d., wang, d., tuncel, s.g. and tuncel, g., 2005. determination of volatile organic compounds in microenvironments by multibed adsorption and short-path thermal desorption followed by gas chromatographic-mass spectrometric analysis. journal of chromatography a. 1099, 43-54. lee, s. c., chu, m.y., ho, k.e., zou, s.c. and wang, x., 2002. volatile organic compounds (vocs) in urban atmosphere of hong kong. chemosphere. 48: 375-382. liu, p.w.g., yao, y.c., tsai, j.h., hsu, y.c., chang, l.p. and chang, k.h., 2008. source impacts by volatile organic compounds in an industrial city of southern taiwan. science of the total environment. 398: 154-163. lung, c.h., horng, t.j., yu, c.s., hsiung, l.k. and yi, m.s., 2007. voc concentration profiles in an ozone non-attainment area: a case study in an urban and industrial complex metroplex in southern taiwan. atmospheric environment. 41: 1848-1860. nguyen, h.t., kim, k.h. and kim, m.y., 2009. volatile organic compounds at an urban monitoring station in korea. journal of hazardous materials. 161: 163-174. parra, m.a., elustondo, d., bermejo, r. and santamaria, j.m., 2009. ambient air levels of volatile organic compounds (voc) and nitrogen dioxide (no2) in a medium size city in northern spain. science of the total environment. 407: 999-1009. ras, m.r., borrull, f. and marca, r.m., 2008. sampling and pre concentration techniques to the determination of volatile organic compounds in air samples. trends in analytical chemistry. doi: 10.1016/j.trac.2008.10.009. ribes, a., carrera, g., gallego, e., roca, x., berenguer, m.j. and guardino, x., 2007. development and validation of method for air-quality and nuisance odours monitoring of volatile organic compounds using multi-sorbent adsorption and gas chromatography/mass spectrometry thermal desorption system. journal of chromatography a. 1140: 44-55. srivastava, a., 2004. source apportionment of ambient vocs in mumbai city. atmospheric environment. 38: 6829-6843. song, y., dai, w., shao, m., liu, y., lu, s., kuster, w. and golden, p., 2008. comparison of receptor models for source apportionment of volatile organic compounds in beijing, china. environmental pollution. xx: 1-10. usepa, 1997. compendium method to-17: determination of volatile organic compounds in ambient air using active sampling onto sorbent tubes, epa/625/r-96/010b, us environmental protection agency, cincinnati, oh 45268. wang, p. and zhao, w., 2008. assessment of ambient volatile organic compounds (vocs) near major roads in urban nanjing, china. atmospheric research. 89: 289-297. who, 2000. air quality guidelines for europe, who regional publications, european series, second edition, no. 91, who, copenhagen. chapter five: discussion 26 construction of allometric relationships to predict growth parameters, stem biomass and carbon of eucalyptus grandis growing in sri lanka s.m.c.u.p. subasinghe * department of forestry and environmental science, university of sri jayewardenepura, sri lanka date received: 04-06-2015 date accepted: 26-10-2015 abstract enhancement of carbon storage through the establishment of man-made forests has been considered as a mitigation option to reduce increasing atmospheric co2 levels. therefore the present study was carried out to estimate the biomass and carbon storages of the main stem of eucalyptus grandis using allometric relationships using the plantations of nuwara eliya and badulla districts in sri lanka. tree diameter and total height were measured for the samples trees and stem volume was estimated using a previously built individual model for the same species. stem biomass was estimated using core samples and carbon was determined using walkley-black method. finally the biomass values were converted separately to the carbon values. non-liner regression analysis was employed for the construction of models which had age as the explanatory variable. linear regression was used in order to build the models to predict the above ground and stem biomass and carbon using volume as the explanatory variable. for both linear and non-linear types, the model quality was tested using r 2 and fitted line plots. according to the results, stem biomass and carbon values at the 7 th year were 110.8 kg and 68.7 kg respectively. stem biomass and carbon values at the 40 th year were 1,095.8 kg and 679.4 kg respectively. carbon content at the age 20 was 62.0% from the stem biomass. exponential models were proven to be better than the logistic models to predict the diameter, height, stem volume, biomass and carbon with age. r 2 values and the fitted line plots indicated that the selected models are of high quality. linear models built to predict the stem biomass and carbon using stem volume also showed the high accuracy of these models which had r 2 values above 97.9%. key words: eucalyptus grandis, forest biomass, forest carbon, allometric equations 1. introduction eucalyptus grandis hill ex maiden also known as flooded gum belongs to the family myrtaceae and is native to the east coast of australia (geary et al., 1983). it is a tall, straight tree which can grow up to 50-55 m in height and 180 cm in diameter and has a widespread thin crown at maturity (fao, 1981). the grey colour bark is thin and deciduous, shedding in strips to expose a smooth surface marked with flowing patterns of silvery white, gray or light green. it is one of the most important commercial eucalypt species and it has been successfully used for pulpwood and fuel; and its wood has potential for poles, pallets, veneer, and other products (geary et al., 1983). according to the sri lanka forestry sector master plan (fsmp 1995), e. grandis was first introduced in late 1800s as a fuel wood * correspondence: upuls@sjp.ac.lk tel: +94 714450339 issn 2235-9370 print/issn 2235-9362 online © university of sri jayewardenepura subasinghe. /journal of tropical forestry and environment vol. 5. no 02 (2015) 26-39 27 for the drying ovens of tea factories and established in large scale in the up country. after 1953, forest department established e. grandis and e. microcorys plantations in the up country of sri lanka, especially in degraded lands for the rehabilitation. however, after realising the value of timber, those plantations are currently mainly maintained as even-aged monocultures to obtain sawn timber, transmission poles and railway sleepers. total extent of e. grandis plantations managed by the forest department in sri lanka is approximately 4,000 ha (bandaratillake, 2000). all tea estates located in the upcountry also maintain large areas of eucalyptus plantations for both timber and fuelwood. if these privately owned plantations are added to the government plantations, sri lanka has a large extent (most probably double the recorded figure) of flooded gum plantations. unfortunately the information on the privately owned plantations is not readily available. global climate change has inspired an increasing interest of scientific and political communities in the study of global carbon storage and of the carbon balance (landsberg et al., 1995). the estimation of biomass is an essential aspect of studies of carbon storage and carbon balance. although weighing the actual tree biomass in the field is undoubtedly the most accurate method to determine tree biomass, it is an extremely time consuming and destructive method, that is generally restricted to small areas and small tree sample sizes (ketterings et al., 2001). use of allometric relationships yields a non-destructive and indirect measurement of biomass compartments, and is often the preferred approach since it is less time consuming and less expensive than direct measurements (st. clair, 1993). these techniques, involve relationships between tree biomass and tree stem diameter and/or height (spelcht and west, 2006). in 1994, niklas said that allometry, relating easily measured variable to other structural and functional characteristics, is the most common and reliable method for estimating biomass, net primary production, and biogeochemical budgets in forest ecosystems (gower et al., 1994; wang, 2006). substantial research programs are usually undertaken to develop such allometric relationships for application with particular tree species in particular forest ecosystems (spelcht and west, 2006). forests play an important role in global carbon budget as carbon sinks and throughout emission of co2 (sedjo 1990; dixon et al., 1994, gamage et al., 2010). forests hold two third of terrestrial carbon and as the forest biomass increase over the time, the stock of sequestered carbon stock in the standing forest and soils will also increase. usually young forests may have a relatively modest carbon stock due to its low biomass, but at the same time generate substantial flows into that stock due to the rapid growth of juvenile trees (roger et al., 1997). brown et al., (1996) estimated that deforestation contributes about 1.8 giga-tonne of carbon per year. however, as forests remove co2 from the atmosphere through photosynthesis, it has been estimated that, the reduction is between 1.1 to 8.0 gigatonne per year. managed forests can function as net sinks for atmospheric co2, despite the period of co2 release at harvesting. in fact, sustainably managed forests are needed to maintain the sequestration capacity of forest ecosystem, i.e., the use of stem wood in forest industry makes it possible to remove carbon into storage outside the forest ecosystem (marland and marland, 1992). apart from aboveground vegetation, belowground tree root biomass, forest floor, and mineral soil provide large c pools (johnson et al., 2003; oliver et al., 2004). however, there has been some disagreement in literature about whether or not an increase in soil carbon may be achieved through forest plantations. furthermore, due to the immense effort required in obtaining a precise estimate of 28 tree root biomass, carbon storage in tree roots is often neglected or estimated from standard root to shoot ratios (kurz et al., 1996; cairns et al., 1997). estimations of growth and yield are important across the full planning spectrum of forest stands from the strategic level through to the operational level (louw and scholes, 2006). the ability to understand and predict forest growth underpins sustainable silvicultural management. accurate predictions of growth and yield of forest plantations remain also important to the forest industry (louw, 1999; dye, 2001). in any modelling project, several aspects of the posed problem need to be reconciled: conceptual, mathematical, engineering and ecological aspects. growth equations have a quite different character from transparent equations; they are heuristic generalisations rather than applications of an underlying theory (hauhs et al., 2003). 2. methodology 2.1 site selection in order to cover a wide geographical range in data collection, even-aged e. grandis monoculture plantations listed in table 1 were selected from nuwara-eliya and badulla forest divisions for the present study. table 1: plantations selected from badulla and nuwara eliya forest divisions for the current study. division plantation planted year badulla nuwara eliya haliela passara bandarawela haputale gurutalawa ohiya bambrarakele bambrarakele i bambrarakele ii bambrarakele bambrarakele dixons corner mahakudugala kandapola kandapola kandapola kandapola kandapola norton bridge pattipola pattipola pattipola pattipola pattipola piduruthalagala pundalu oya pundalu oya ramboda rilagala sandathenna 1972 1987 1980 1972 1972 1970 1979 1975 1975 1971 1967 1978 1977 2000 1995 1991 1982 1987 1971 2000 1991 1987 1972 1967 1967 1987 1983 1979 1974 1975 subasinghe. /journal of tropical forestry and environment vol. 5. no 02 (2015) 26-39 29 2.2 sampling and data collection randomly demarcated 0.02 ha circular sample plots were used for the data collection. the number of samples needed at 95% probability level was determined by using the equation 1 after a preliminary sampling procedure. the numbers of samples vary for each plantation from 5 to 10 (philip, 1994). 2 2 %)( %)(4 ae cv n   (1) where: 4 = approximation of the t value at 95% probability cv = coefficient of variation among the selected plots n = number of sample plots required 2.3 measurements taken e. grandis plantations selected for the present study was even-aged monocultures and age of the selected plantations were obtained by the fordata database maintained by the sri lanka forest department. diameter at breast height (dbh), i.e., the diameter of the tree stem at the point of 1.3 m above the ground from the uphill side was measured using a diameter tape. total tree height which is the height from the bottom of the tree to its highest growing point was measured using a blume-leiss altimeter. 2.4 calculation of stem volume the stem volume of e. grandis trees were calculated using the model given in equation 2 developed by subasinghe (2001) for the same species. )(3648.0 hgv  (2) where: g = tree basal area (calculated from tree diameter), m 2 h = total height, m v = stem volume, m 3 2.5 estimation of stem biomass and carbon early studies conducted on forest trees indicated that the biomass per unit volume (wood density) does not become significantly different along the stem from the bottom to the top (samarasekara, 2013; subasinghe and haripriya, 2014). therefore, it was decided to use only one core sample from the tree stem for the analysis of carbon and biomass. those core samples were extracted at the breast height and green volume and oven dry weight were measured. then those were oven-dried at 105 0 c until a constant weight was achieved. the dry weight of the entire main stem was then calculated using equation 3. c c s v vw w   (3) where: vc = green volume of the core sample, m 3 wc = dry weight of the core sample, kg ws = total dry mass of the stem, kg 30 the available carbon was determined by using the walkley and black method for the dried samples and it was converted to the entire stem using equation 4. v v c c c c s  (4) where: cc = c amount of the core sample, kg cs = c amount of the stem, kg 2.6 development of relationships diameter and height growth of the trees show increasing relationships with age and therefore allometric relationships between growth parameters and the age were determined using the methods described in the following sections. in order to build the allometric models to identify the variation of dbh, total height and stem volume with the age, the relationships shown in the equations 5, 6 and 7 were used. dbh = f (age) (5) height = f (age) (6) stem volume = f (age) (7) according to the biological growth patterns, linear relationships of the selected variables with age could not be accepted. therefore non-linear regression analyses were used to quantify the above mentioned relationships using genstat software. stem biomass and stem carbon should exhibit a strong relationship with the stem volume and therefore the following relationships were also built using linear regression analysis using genstat software. stem biomass = f (stem volume) (8) stem carbon = f (stem volume) (9) linear models were fitted to the theoretically established relationships where volume was the explanatory variable. all those models were developed without intercepts in this study because when the explanatory variable is zero, the respective response variables should not exist. both exponential and logistic curves were fitted to the data for the relationships (equations 5 to 7) had age as the explanatory variable. 2.7 evaluation of the models in order to identify the quality of the models, it was decided to use both quantitative and qualitative indicators. coefficient of determination (r 2 ) was used as the quantitative indicator and fitted line plots were used as qualitative indicators because all relationships had one explanatory variable. 3. results the summary of the measured variables from the selected plantations is given in table 2 and figure 1. according to the data of table 2 and figure 1, plantations of age 20 and 24 indicated unusually higher growth rates than the rest of the plantations. this could be due to the impact of site qualities on the growth of e. grandis trees growing in those plantations. subasinghe. /journal of tropical forestry and environment vol. 5. no 02 (2015) 26-39 31 table 2: summary of the measured and estimated variables from the selected plantations. age, yr dbh, cm height, m stem volume, m 3 stem biomass, kg stem carbon, kg 7 12 16 20 24 28 32 36 40 20.3 21.7 25.6 37.6 28.3 49.2 45.9 44.1 55.9 22.3 24.1 25.6 34.8 28.0 36.3 35.1 38.1 42.8 0.263 0.325 0.481 1.410 0.643 2.518 2.119 2.123 3.563 110.8 125.8 191.8 463.5 248.4 851.4 732.3 695.7 1095.8 68.7 72.5 138.5 287.4 163.8 520.7 479.0 468.0 679.4 figure 1: variation of average dbh (cm), height (m) and volume (m 3 ) values with (± se). 3.1 carbon and biomass variation with the age figure 2: variation of stem biomass and carbon values with the age. 32 figure 2 illustrates the variation of the average carbon and biomass values for each tree. according to that graph, the stem biomass of the average tree varies from 110.8 kg at the age 7 to 1,095.8 at the age 40. this indicates an average biomass increment of 29.8 kg per tree per annum. stem carbon varies from 68.7 kg at the age 7 to 679.4 kg at the age 40 (figure 2) showing an annual carbon storage of 18.5 kg per tree. the average stem carbon percentage was 62.0% from the biomass at age 20. 3.2 variation of dbh, height and stem volume with the age all three relationships had age as the only explanatory variable and therefore both exponential and logistic curves could be fitted. however, the logistic models showed comparatively lower r 2 values and in addition those were more complex than the exponential models. therefore the exponential models shown in equations 10, 11 and 12 were selected for the prediction of dbh, total height and stem volume respectively using age. r 2 values for the selected models were 79.1%, 84.0% and 80.1% for the models 10, 11 and 12 respectively. the fitted line plots of those models are given in figures 3 to 5. (10) (11) (12) where: dbh = diameter at breast height, cm h = total tree height, m v = stem volume, m 3 figure 3: average dbh values and the fitted line of equation10. subasinghe. /journal of tropical forestry and environment vol. 5. no 02 (2015) 26-39 33 figure 4: average tree height values and the fitted line of equation 11. figure 5: average stem volume values and the fitted line of equation 12. 3.3 variation of stem biomass and carbon with tree age the exponential models resultant for the prediction of stem biomass and carbon with age are given in equation 13 and 14. the estimated r 2 values were 78.7% and 82.1% respectively. figures 6 and 7 show fitted line plots of these two models. (13) (14) where: bmstem = stem biomass, kg cstem = stem carbon, kg 34 figure 6: average stem biomass values and the fitted line of equation 13. figure 7: average above ground stem ground carbon values and the fitted line of equation 14. 3.4 variation of biomass and carbon with the stem volume unlike the previous models, linear modes were fitted to identify the relationships of stem biomass and carbon with stem volume. those models are given in equations 15 to 16. (15) (16) both models resulted very high r 2 values proving strong relationships of biomass and carbon with the stem volume. those values were 98.9% and 97.9%. it was important to observe that the intercept of the model 15 was significant. however, in accordance with the biological reality where there is no biomass or carbon storage without stem volume. therefore although the intercept was significant, the model was re-fitted to the data without the intercept to be compatible with the biological reality. the fitted line plots of those two models are given in figures 8 and 9. subasinghe. /journal of tropical forestry and environment vol. 5. no 02 (2015) 26-39 35 figure 8: average stem biomass values and the fitted line of equation 15. figure 9: average stem carbon values and the fitted line of equation 16. 4. discussion all three models built in this study using age as the explanatory variable showed positive and exponential growth pattern with the age. however, when the average values were observed in table 1 and figure 1, there were unusual variations of the measured values. the growth values were high at age 20 and 28 when compared with the trend of the growth in the plantations of other ages. these changes may have occurred due to the impact of the site quality on tree growth. the growth dynamics of the plant populations were determined not only by the species specific properties, but also by the biotic and abiotic factors such as neighbourhood, competition and environmental heterogeneity. this could also be one of the reasons of having unusual observations at certain ages of the e. grandis plantations used in this study. biomass was estimated in this study directly using the core samples taken at the breast height of trees without felling them. the density of the core samples was estimated in dry weight per green volume (philip, 1994). finally separate models were built in this study to predict biomass and carbon values of different above ground parts of the trees. similar studies were conducted by xio and ceulemans (2004) and wang (2006). in a different approach to the method used in this study, 36 destructive sampling has also been frequently used for biomass and carbon studies of forest trees by many researchers in the past, e.g., xio and ceulemans (2004),williams and gresha (2006). r 2 values were used as the quantitative method of model evaluation in the present study. those resultant r 2 values varied from 79.1% to 98.9% for different models. saha et al. (2004) and wang (2006) also found similar variations in their studies on biomass and carbon of forest tree species. inventory data have often been used to estimate the biomass and carbon contents in tropical forests (brown and lugo, 1992) and in europe (kauppi et al., 1992). most of such models were developed using dbh and height which are the common inventory data available in many countries (segura and kanninen, 2005). considering the error that can be occurred by measuring various individual height terms, segura and kanninen (2005) recommended to develop models using dbh as the single explanatory variable to predict the tree carbon. however, due to the differences of the objectives, the present study built the first three models using age as the explanatory variable. age has become one of the essential explanatory variables for tree growth prediction in forestry (e.g.: palahi et al., 2004, adame et al., 2006; salas and garcia, 2006). however, according to lee et al. (2004), although tree age is an important influencing variable on radial growth, it might simply be not available in practice. however, the attempts made by them to exclude the age from the explanatory variables to predict dbh growth of pine and oak were not successful and the resultant models indicated poor statistical performances. in their modelling process, calama et al. (2003) and adame et al. (2006) emphasised the importance of data chosen for fitting different functions containing all possible combinations of variables. fernandez and norero (2006) performed forty five linear regressions in modelling the growth of branches of individual trees in each site, management and type of branch. however, exponential models were identified as the best ways of predicting the selected response variables against age in the present study. if the general form of the exponential model is considered (equation 17), the parameter b became higher than one (b>1.0) for all exponential models constructed in the present study. this indicated that the selected exponential variables were growing rapidly for e. grandis even after 40 years of planting. if more data were collected beyond 40 years of age, there could be a possibility of having b<1.0 showing a typical sigmoid growth of biological variables. (17) where: x = explanatory variable, i.e., age in the present study y = response variable b1, b2 = regression coefficients in mathematical model building, it is common to transform variables into biologically accepted forms (logarithmic, square root, square and inverse) to obtain high accuracy in the predictions (e.g., vanclay, 1994, segura and kanninen, 2005; subasinghe and gunarathne, 2007; subasinghe and munasinghe, 2011). moreover, complex transformations are sometimes used in forest growth modelling. as an example, boisvenue et al. (2004) used arcsine and cosine transformations of selected explanatory variables to model the height growth of small trees in mixed species stands in southern british columbia in canada. however, such transformations were not required for the linear form of subasinghe. /journal of tropical forestry and environment vol. 5. no 02 (2015) 26-39 37 biomass and carbon prediction models built using volume as the explanatory variable because the resultant r 2 values and the fitted line plots proved that the models built in this study by using untransformed variables were strong enough. it is commonly believed that a model can be no more accurate than the data on which it is based. however, models can amplify patterns and discard unwanted noise, they can be more accurate than the data used to build them (burkhart, 2003). for most forested areas in tropical regions, there are limited numerical data describing the impacts of forestry practice that can be used to support the development of sustainable management practices. anecdotal evidence may be available, but is generally of a subjective nature and site specific (phillips et al., 2003). continuous growth records measured from permanent sample plots are not available in sri lanka and therefore the measurements were taken from the temporary sample plots. however, the plantations were selected covering the entire region which is favourable for the rose gum growth in sri lanka along a series of age to minimise the drawback which can arise from not using permanent sample plot data. references adame, a., hynynen, j, canellas, i., del rio, m. 2006. individual-tree diameter growth model for rebollo oak (quercus pyrenaica willd.) coppices. forest ecology and management 255: 10111022. bandaratillake, h.m., 2000. administration report of the conservator of forests sri lanka for the year 2000. forest department, ministry of agriculture, lands and forestry, sri lanka. boisvenue, c., temesgen, h and marshall, p., 2004. selecting a small tree height growth model for mixed species stands in the southern interior of british columbia, canada. forest ecology and management, 202: 301-312. brown, s., gillespie, j.r. and lugo, a.e., 1996. biomass of tropical forests of south and southeast asia, canadian journal of forest research, 21: 111-117. brown, s., lugo, a.e., 1992. above ground estimates for tropical moist forests of the brazilian amazon. interciencia, 17(1): 8-27. burkhart, h.e., 2003. suggestions for choosing an appropriate level for modelling forest stands. in a. amerao, d. reed and, p. soares (ed) modelling forest systems, cab international, uk. calama r., cañadas n., montero g., 2003. inter-regional variability in site index models for even-aged stands of stone pine (pinus pinea l.) in spain. annals of forest science, 60: 259-269. cairns, m.a., brown, s., helmer, e.h., baumgardner, g.a., 1997. root biomass allocation in the world’s upland forests. oecologia, 111, 1–11. dixon, r.k., brown, s., houghton, r.a, soloman, a.m., trexier, m.c., wisniewski, j., 1994. carbon pools and flux of global forest ecosystems, science, 263:185-190. dye, p., 2001. modelling growth and water use in four pinus patula stands with the 3-pg model. south african forestry journal, 191: 53-63. fao, 1981. eucalyptus for planting. fao forestry series no. 11, food and agriculture organisation of the united nations, rome. fernandez, m.p., norero, a., 2006. relation between length and diameter of pinus radiata branches. scandinavian journal of forest research, 21: 124-129. fsmp, 1995. forestry sector master plan. forest department, ministry of agriculture, lands and forestry, sri lanka. 38 gamage, y.m.m, subasinghe, s.m.c.u.p, hettiarachchi, d.s., 2101, change of seed gerwination rate with storage time of santalum album seeds, proceedings of 18 th international forestry and environmental symposium, university of sri jayewardenepura, sri lanka. geary, t.f., meskimen, g.f. and franklin, e.c., 1983. growing eucalypts in florida for industrial wood production. gen. tech. rep. se-23. asheville, nc: u.s. department of agriculture, forest service, southeastern forest experiment station. gower, s.t., gholz, h.l., nakane, k., baldwin, v.c., 1994. production and carbon allocation patterns of pine forests. ecological bulletin, 43: 115-135. hauhs, m., knauft, f.j., lange, h., 2003. algorithmic and interactive approaches to stand growth modelling. in a. amerao, d. reed and, p. soares (ed) modelling forest systems, cab international, uk. johnson, d.w., todd jr., d.e., tolbert, v.r., 2003. changes in ecosystem carbon and nitrogen in a loblolly pine plantation over the first 18 years. soil science society american journal, 67: 15941601. kauupi, p.e., mielikainen, k, kuusela, k., 1992. biomass and carbon budget of european forests, 1971 to 1990. science 256(5053): 70-74. ketterings, q.m., coe, r., van noordwijk, m., ambagau, y., palm, c.a., 2001. reducing uncertainty in the use of allometric biomass equations for predicting above-ground tree biomass in mixed secondary forests. forest ecology and management, 146: 199-209. kurz, w.a., beukema, s.j., apps, m.j., 1996. estimation of root biomass and dynamics for the carbon budget model of the canadian forest sector. canadian journal of forest research, 26: 19731979. landsberg, j.j., linder, s., mcmurtrie, r.e., 1995. effects of global change on managed forests. a strategic plan for research on managed forest ecosystems in a globally changing environment. global change and terrestrial ecosystems. core project of the igbp, canberra, 1-17 pp. lee, w.k., von gadow, k., chung, d.j., lee, j.l., shin., m.y., 2004. dbh growth model for pinus densiflora and quercus variabilis mixed forests in central korea. ecological modelling, 17: 187-200. louw, j.h., 1999. a review of site–growth studies in south africa. south african forestry journal, 185: 57-65. louw, j.h. and scholes, m.c.., 2006. site index functions using site descriptions for pinus patula plantations in south africa. forest ecology and management, 225:94-103. marland, g., marland, s., 1992, should we store carbon in trees? water, air and soil pollution, 64: 181-195. niklas, k.j., 1994. plant allometry: the scaling of form and process. chicago, il: univ. of chicago press. oliver, g.r., pearce, s.h., kimberly, m.o., ford-robertson, j.b., robertson, k.a., beets, p.n., garrett, l.g., 2004. variation in soil carbon in pine plantations and implications for monitoring soil carbon stocks in relation to land-use change and forest site management in new zealand. forest ecology and management, 203: 283-295. palahi m., tome m., pukkala t., trasobares a., montero g., 2004. site index model for pinus sylvestris in north-east spain, forest ecology and management, 187: 35-47. philip, m.s., 1994. measuring trees and forests. 2nd ed. cab international, uk. phillips, p.d., brash, t.e., yasman, i., subagyo, p., van gardingen, p.r., 2003. an individual-based spatially explicit tree growth model for forests in east kalimantan (indonesian borneo). ecological modelling, 159: 1-26. subasinghe. /journal of tropical forestry and environment vol. 5. no 02 (2015) 26-39 39 rodger, a.s., samson, r.n., sniewski, j.w., 1997. economics of carbon sequestration in forestry, washington, usa. saha, j.p., rossa, m.s., kopturb, s., snyder, j.r. 2004. estimating aboveground biomass of broadleaved woody plants in the understory of florida keys pine forests. forest ecology and management, 203: 319-329. salas, c., garcia, o., 2006. modelling height development of mature nothofagus oblique. forest ecology and management, 229: 1-6. samarasekara, s.c., 2013. variation of quantity and quality of santalum album l. oil with geographical, topographical and host species in selected districts, bsc dissertation, department of forestry and environmental science, university of sri jayewardenepura, sri lanka. sedjo, r., 1990. the global carbon cycle. journal of forestry, 88: 33-34. segura, m., kanninen, m., 2005. allometric models for tree volume and total above ground biomass in a tropical humid forest in costa rica. biotropica, 37(1): 2-8. st. clair, j.b., 1993. family differences in equations for predicting biomass and leaf area in douglas fir (pseudotsuga menziesii var. menziesii). forest science, 39:743-755. subasinghe, s.m.c.u.p., 2001. construction of an individual tree volume prediction model for eucalyptus grandis hill ex maiden in sri lanka, research report, university of sri jayewardenepura, sri lanka. subasinghe, s.m.c.u.p. and gunarathne, w.p.k. 2007. construction of a precise growth model to predict the individual tree stem volume for mature tectona grandis l.f. (teak). sri lanka forester, 30-31: 1-13. subasinghe, s.m.c.u.p. and munasinghe, g.b., 2011. estimation of above ground tree biomass and carbon of pinus caribaea (morelet). journal of tropical forestry and environment. 1(1): 56-70. subasinghe, s.m.c.u.p. and haripriya, a.m.r., 2014. prediction of stem biomass of pinus caribaea growing in the low country wet zone of sri lanka. journal of tropical forestry and environment, 4(1): 40-49. vanclay, j.k., 1994. modelling forest growth and yield: applications to mixed tropical forests. cab international, uk. wang, c., 2006. biomass allometric equations for 10 co-occurring tree species in chinese temperate forests, forest ecology and management, 222: 9-16. williams, t., gresham, c.a. 2006. biomass accumulation in rapidly growing loblolly pine and sweet gum. biomass and bioenergy 30: 370-377. xiao, c.w., ceulemans, r. 2004. allometric relationships for belowand aboveground biomass of young scots pines. forest ecology and management, 203: 177-186. chapter 1 1 journal of tropical forestry and environment vol. 01, no. 01 (2011) 1-13 a brief global perspective on biomass for bioenergy and biofuels richard vlosky*1 and roger smithhart2 1director and crosby land & resources endowed professor in forest sector business development louisiana forest products development center, louisiana state university agricultural center baton rouge, louisiana, united states 2graduate research assistant, louisiana forest products development center baton rouge, louisiana, united states *correspondence: e-mail rvlosky@agcenter.lsu.edu, tel:001 225 578 4527 fax: 001 225 223-1931 issn 2235-9370 print/ issn 2235-9362 online ©2011 university of sri jayewardenepura summary biomass has a large energy potential. a comparison between the available potential with the current use shows that, on a worldwide level, about two-fifths of the existing biomass energy potential is used. in most areas of the world the current biomass use is clearly below the available potential. only for asia does the current use exceed the available potential, i.e. non-sustainable biomass use. therefore, increased biomass use, e.g. for upgrading is possible in most countries. a possible alternative is to cover the future demand for renewable energy, by increased utilization of forest residues and residues from the wood processing industry, e.g. for production of densified biofuels (parrika, 2004). if carried out on a large scale, the increased use of agricultural resources for energy will have the effect of raising the prices of most commodity crops and reducing the need for subsidies – with particular benefit for producers of commodity crops in developing countries. an aggressive program of bioenergy development could lead to reductions in government support to farmers without any loss of income. the long-term success of bio-based facilities and markets is dependent in part on the level of commitment of feedstock from forest landowners and farmers. forest, crop, and animal residues present considerable potential as a biomass feedstock. they are renewable, sustainable, locally available, and often considered carbon-neutral when compared to fossil fuels (hoogwijk, 2004; mathews, 2008). feature article 2 introduction in recent years, policy makers, legislators, developers, and energy producers have been searching for less expensive, more reliable, and renewable domestic energy sources. hydro-electric, geothermal, wind, solar, and biomass energy are the most common forms of renewable energy sources that are being used to alleviate our dependency on fossil fuels. biomass is an attractive choice because it is cost efficient, clean and the only current renewable source of liquid transportation fuel (perlack et al. 2005; u.s.d.o.e. 2010; u.s.d.a. 2009). the environmental movement of the 1960’s spurred the creation of several policies intended to reform emission and pollution practices of the industrial sector in order to provide the nation a cleaner environment. persistent concerns of society continuing to become more highly mechanized and dependent on fossil fuels created an interest in bio-based projects (smithhart, 2011). biomass essentially began to be examined in the 1970’s as a solution to the energy crisis resulting from heavy regulations and predicted shortages within the fossil fuel industry. however, the discovery of fossil fuel reserves followed by a deregulation of the oil industry led to an era of cheap energy. more recently, occurrences such as a global recession along with instability within oil-rich countries, among other factors, inflated energy prices to unprecedented levels (smithhart, 2011). concurrent with increased energy prices is a revitalization of environmental awareness. the 21st century is the beginning of a period with increasing requirements for holistic approaches land stewardship supported by science-based methods to help solve environmental issues. issues fueling these requirements are soil, water, and air quality to name a few. added to environmental concerns is increasing demand for energy. increases in population, survival rates, and technological advancements are just a few of the social issues augmenting stress to the energy predicament. many energy producers, developers, legislators, academia, policy makers, and the public are searching for alternative energy sources to alleviate the energy demand and dependency on fossil fuels. these interested parties view renewable energy sources as clean and sustainable solutions. of the renewable energy sources, biomass feedstock from forestry, agricultural, and livestock industries offer potential to help mitigate environmental issues and stabilize energy needs (smithhart, 2011). recently, several innovations and technology advancements have come from the biomass industry. advancements within the industry are primarily focused on the areas of harvesting and collection, storage, pretreatment, and conversion of biomass to bio-based products. the preprocessing and pretreatment of biomass also increases the potential gain of biomass to bioenergy efficiency (meza et al. 2008; jackson et al. 2010; zhu and pan 2010). once treated, biomass resources can be converted to energy using a variety of processes to generate electricity, fuel vehicles, residential and commercial heating, as well as provide process heat for industrial facilities. with advancements in biomass technologies in place, energy producers seek sustainable supplies of biomass feedstock to ensure long-term success. such feedstocks can come from the forestry and agricultural communities. vlosky & smithhart/journal of tropical forestry and environment vol. 01, no. 01 (2011) 1-13 3 journal of tropical forestry and environment vol. 01, no. 01 (2011) 1-13 the continued development of bio-based products and facilities may help to establish several market opportunities for forest landowners, farmers, and poultry producers by providing feedstock in the form of post-harvest residues and dedicated energy crops including trees, crop residues, and animal wastes. if the success of the biomass industry occurs, the diverse markets that emerge will secure the demand for a sustainable supply of biomass feedstock (smithhart, 2011). augmenting fundamental markets are policy initiatives in the form of mandates, incentives, and tax provisions. government agencies in partnership with industry and academia will likely be focused on achieving goals requiring specific amounts of renewable fuels be produced by future deadlines. any increases in demand for a sustainable supply of biomass feedstock will challenge forest landowners and farmers to adopt innovative practices. they may be asked or forced into participating in government programs that support bio-based production. understanding forest and agricultural producers’ knowledge and attitudes towards biomass technologies and initiatives can help energy producers and policy makers develop programs tailored for these important groups (smithhart, 2011). since the kyoto protocol came into effect in 2005, more attention has been paid to the development of biomass recourse use. this has occurred not only in the industrialized countries, which have an obligation to reduce greenhouse gas emissions under the kyoto protocol, but also in developing countries. biomass for fuel biomass is considered to be one of the key renewable resources of the future at both smalland large-scale levels. it already supplies 14 % of the world’s primary energy consumption. but for three quarters of the world’s population living in developing countries, biomass is the most important source of energy. with increases in population and per capita demand, and depletion of fossil-fuel resources, the demand for biomass is expected to increase rapidly in developing countries. on average, biomass produces 38 % of the primary energy in developing countries (90 % in some countries). biomass is likely to remain an important global source in developing countries well into the next century (slovak non-profit organizations, 2011). managed properly, biomass energy (or bio-energy) can be sustainable, environmentally benign and economically sound. moreover, biomass energy creates substantial local employment. the advantages are also being recognized in industrialized countries, and several governments have successfully adopted articulate policies for promoting biomass energy. (source: biomass: more than a traditional form of energy, a publication of the fao regional wood energy development program in asia in cooperation with the ec-asean cogen program and the asean-ec energy management training research centre.) there is an enormous biomass potential that can be tapped by improving the utilization of existing resources and by increasing plant productivity. bioenergy can be modernized through the application of advanced technology to convert raw biomass into modern, easy-to-use carriers (such as electricity, liquid or gaseous fuels, or processed solid fuels). therefore, much more useful energy could be extracted from biomass than at present. this could bring very significant social and economic benefits to both rural and urban areas. the present lack of access to convenient sources limits the quality of life of millions of 4 people throughout the world, particularly in rural areas of developing countries. growing biomass is a rural, labor-intensive activity, and can, therefore, create jobs in rural areas and help stem rural-to-urban migration, whilst, at the same time, providing convenient carriers to help promote other rural industries (slovak non-profit organizations, 2011). it is now possible with good management, research, and planting of selected species and clones on appropriate soils to obtain 10 to 15 t/ha/yr in temperate areas and 15 to 25 t/ha/yr in tropical countries. record yields of 40 t/ha/yr (dry weight) have been obtained with eucalyptus in brazil and ethiopia. high yields are also feasible with herbaceous (non-woody) crops where the agroecological conditions are suitable. for example, in brazil, the average yield of sugarcane has risen from 47 to 65 t/ha (harvested weight) over the last 15 years while over 100t/ha/yr are common in a number of areas such as hawaii, south africa, and queensland in australia. it should be possible with various types of biomass production to emulate the three-fold increase in grain yields which have been achieved over the past 45 years although this would require the same high levels of inputs and infrastructure development. however, in trials in hawaii, yields of 25 t/ha/yr have been achieved without nitrogen fertilizers when eucalyptus is interplanted with nitrogen fixing albizia trees (de bell et al., 1989). figure 1: ethanol plant in brazil uses the sugar cane to produce sugar, bio-ethanol and electricity with the waste material world-wide, fermentation capacity for fuel ethanol has increased eightfold since 1977 to about 20 billion liters per year. latin america, dominated by brazil, is the world’s largest production region of bioethanol. countries such as brazil and argentina already produce large amounts, and there are many other countries such as bolivia, costa rica, honduras and paraguay, among others, which are seriously considering the bioethanol option. alcohol fuels have also been aggressively pursued in a number of african countries currently producing sugar kenya, malawi, south africa and zimbabwe. others with great potential include mauritius, swaziland and zambia. some countries have modernized sugar industry and have low production costs. many of these countries are landlocked which means that it is not vlosky & smithhart/journal of tropical forestry and environment vol. 01, no. 01 (2011) 1-13 5 journal of tropical forestry and environment vol. 01, no. 01 (2011) 1-13 feasible to sell molasses as a by-product on the world market, while oil imports are also very expensive and subject to disruption. the major objectives of these programs are: diversification of the sugarcane industry, displacement of energy imports and better resource use, and, indirectly, better environmental management. these conditions, combined with relatively low total demand for liquid transport fuels, make ethanol fuel attractive. global interest in ethanol fuels has increased considerably over the last decade despite the fall in oil prices after 1981. in developing countries interest in alcohol fuels has been mainly due to low sugar prices in the international market, and also for strategic reasons. in the industrialized countries, a major reason is increasing environmental concern, and also the possibility of solving some wider socio-economic problems, such as agricultural land use and food surpluses. as the value of bioethanol is increasingly being recognized, more and more policies to support development and implementation of ethanol as a fuel are being introduced (slovak non-profit organizations, 2011.) expanding use of biofuel will provide precious opportunities for rural people to improve their welfare, since most of the energy crops are mainly produced by small-scale farmers who are vulnerable to price fluctuations. an increasing demand for energy crops has the potential to contribute to increased and stabilized prices of their produce. moreover, the installation of biofuel processing plants will increase job opportunities, mainly for rural poor people. this is because the biofuel production should be done near the feedstock production areas, due to the high transportation costs of bulky raw materials. on the other hand, if the government fails to manage the biomass resource development appropriately, some negative impacts will occur such as natural forest destruction, conflict with food production, and contamination of natural water systems by excess inputs into farmlands (unescap-capsa, 2008.) the production of biofuel feedstock provides an opportunity for many countries to capture part of the global fuel market share by investing in production and upstream refining, both to save foreign currency and to earn from exports. biofuels also provide a unique and vast market to link remote, generally uneconomic and degraded areas, where many of world’s poorest people live, to global markets (unescap-capsa, 2008). these trends not only open a vast area of opportunity for the poor, many of whom live in areas well-suited to biofuel production, but they may also cause some basic shifts in agricultural production patterns as land is diverted from food crop production to production of biofuels to meet the increasing energy needs of the world (unescap-capsa, 2008) biomass conversion to energy biomass resources can be converted to energy using a variety of processes in order to meet the need of generating electricity, fueling vehicles, residential and commercial heating, and providing process heat for industrial facilities. although conversion technologies of biomass are extensive and numerous, most of the methods mentioned are geared toward uses in advanced bio-facilities and are flexible in that they can also be used in other agricultural applications. biomass conversion technologies can be broadly divided into two categories: thermochemical processes and biochemical processes. direct combustion of biomass is one of the most common and oldest processes used today. the process of direct combustion combines air with fuel to produce heat, water, carbon dioxide, ash, and 6 trace compounds. for residential purposes, energy can be created using direct combustion in stoves and small scale furnaces. direct firing at an industrial level uses furnaces or boilers to produce process heat, electricity, or both in a combined heat and power (chp) system. some of the most common biomass combustion boiler designs are pile burners, stoker-fired furnaces (fixed bed furnaces), suspension-fired furnaces (pulverized fuel systems), and fluidized bed furnaces (saidur et al., 2011). pile burners and stoker-fired furnaces require less capital investment than other combustion technologies; however, they have less efficiency gains (jackson et al., 2010). suspensionfired furnaces achieve high efficiency utilizing technology common to the coal industry for coal-fired furnaces. fluidized bed furnaces are new to boiler technologies that have an ability to handle a wider variety of fuels and moisture content as well as having the highest thermal conversion efficiencies due to more complete combustion when compared to other boiler technologies (saidur et al., 2011). potentially, chp systems have a wide range of small and large scale applications combined with higher efficiencies rendering lower emissions than systems producing separate heat and power. in gasification, biomass is heated in a high temperature environment with steam, air, and oxygen until volatile gases are released (combs, 2008). the gaseous mixture of hydrogen, carbon monoxide, carbon dioxide, and other compounds can be mixed with oxygen and burned to produce steam to operate a turbine and generate electricity. alternatively, the gases can be cooled, filtered, purified, and stored as a synthesis gas, or syngas, to be used as fuel for internal combustion engines, gas turbines, etc. a major cost associated with gasification is tar removal and/or clean up (jackson et al., 2010). however, another gasification process using supercritical water (high temperature steam conditions) offers low levels of char formation and the ability to use high moisture feedstock (jackson et al., 2010). pyrolysis is the gasification of biomass in the absence of oxygen and converts wood biomass to a mixture of solid, liquid, and gas (saidur et al., 2011). the advantages of pyrolysis include a flexible process of converting solid biomass into an easily stored and transportable fuel, which can be successfully used for the production of heat, power, and chemicals. slow pyrolysis (e.g. charcoal production) converts feedstock using relatively low temperature levels and long reaction times, whereas fast pyrolysis produces small molecules by converting feedstock at high temperature levels (jackson et al., 2010). the process transforms the biomass into pyrolysis oil (or bio-oil) or syngas without creating ash or energy directly. torrefaction is a form of mild pyrolysis that pre-treats wood biomass at relatively low temperatures of 200-300°c in the absence of oxygen (bergman and kiel, 2005). gasification of wood biomass is comparatively low at less than 700°c due to high oxygen to carbon (o/c) ration of the fuel and moisture content leading to thermodynamic losses (prins et al., 2006). as a pretreatment to gasification, torrefaction produces a solid material with high energy efficiencies, lower mc, lower o/c ratio, and is hydrophobic in nature (jackson et al., 2010). also, it improves the properties of biomass enabling more efficient cofiring at bio-facilities (bergman and kiel, 2005). biochemical conversion is a chemical decomposition of biomass’ cell wall using cellulase enzymes or acids in order to extract sugars for conversion to ethanol (u.s.d.o.e., 2008). specifically, lignocellulosic hydrolysis is a process of utilizing cellulase enzymes to produce sugar. after the hydrolysis stage, fermenting organisms (e.g. yeast) are added to the mixture inside the fermentor to convert sugars to alcohol and carbon dioxide (jackson et al., 2010; u.s.d.o.e., 2008). vlosky & smithhart/journal of tropical forestry and environment vol. 01, no. 01 (2011) 1-13 7 journal of tropical forestry and environment vol. 01, no. 01 (2011) 1-13 biomass conversion challenges in the u.s., shifting power generating capacity to biomass will not be easy. biomass as a fuel source for large-scale power generation is in its infancy. suppliers and supply chains have not yet been developed on the scale necessary to supply volume of biomass necessary to meet u.s. power needs. unlike the coal supply chain that has been in place for many years, it is not clear at present how the biomass supply chain will or should develop. this is made more complex as numerous utilities are considering entering the biomass market before it is well understood how the competition for fuels sources could evolve. key questions for a utility considering a conversion to biomass is likely to include the following: type of biomass: wood vs. agricultural products, raw vs. pelletized, purpose grown vs. byproduct/residual; torrefaction; specifications (btu content, moisture content, size, emissions); sourcing: biomass origins, suppliers, producer facility sizes, pellet plant locations (if applicable); transportation: modal options, equipment requirements, unloading infrastructure, delivery quantities; storage/handling: type of fuel storage (indoor for certain types of biomass pellets), conveying infrastructure, dust control systems, fire suppression systems and; boiler: type of boiler to use or boiler conversion options. each involves a variety of options and trade-offs that must be considered when developing a biomass supply chain. in addition, each may include significant capital requirements. for example, boiler modifications, transportation equipment, unloading infrastructure, storage facilities and other potential requirements could add up to a significant expense depending on the needs of a specific utility or generating facility. (clair, 2010) primary biomass feed-stocks: wood and agricultural materials where great civilizations have evolved, wood has been universally present and utilized. primitive uses for wood included tools, weapons, shelter, and an energy source. as societies have advanced, so has their use of wood. besides cooking, heating, weaponry, and furniture making, americans began to develop advanced applications for wood in industrial settings. developments in industrial construction led to the building of water mills, wind mills, machinery frames, and mechanized machinery such as axles and gears (stuart and grace, 2009). as an energy source wood was, and still is, being used in direct combustion devices such as fireplaces, woodstoves, and industrial boiler systems (hewett et al., 1981). wood may be the best-known example of biomass. when burned, the wood releases the energy the tree captured from the sun’s rays. but wood is just one example of biomass. various biomass resources such as agricultural residues (e.g. bagasse from sugarcane, corn fiber, rice straw and hulls, and nutshells), wood waste (e.g. sawdust, timber slash, and mill scrap), the paper trash and urban yard clippings in municipal waste, energy crops (fast growing trees like poplars, willows, and grasses like switchgrass or elephant grass), and the methane captured from landfills, municipal waste water treatment, and manure from cattle or poultry, can also be used (slovak non-profit organizations, 2011.) wood energy is drawing increasing attention as an environmentally friendly source of energy. wood is still people’s main source of fuel for cooking, processing and preserving food, and will continue to be for many years to come. worldwide, 2 billion people depend on wood for cooking, a basic step in ensuring proper nutrition. in many developing countries, fuelwood supplies as much as 97 percent of total energy consumption. wood-based energy systems are the most readily available in many areas and, 8 when properly managed, they are not only versatile and sustainable but also effective in generating income and jobs (wto, 1999) although most research on biomass as an energy source was primarily on wood biomass agriculture continues to grow in interest as a cellulosic feedstock (bain, 1993). with agricultural productivity on the rise, cellulosic biomass from agricultural feedstock has great potential to displace future gasoline production (fuglie, 2010; kim and dale, 2004). advancements in plant breeding have resulted in increased yields and quality (dimitri et al., 2005). thus, cellulosic biomass sources offer immense potential as feedstock for future biofuel production (westscott, 2007; powlson et al., 2005). figure 2: logging slash and other wood residues left after timber harvests are ideal sources of wood biomass for energy production biomass and energy development in developing countries though developing countries have no obligation under the current kyoto protocol, if an industrialized country assists a developing country in reducing emissions, it can be counted as an achievement by the industrialized country. the mechanisms are expected to promote investment in renewable energy development in developing countries, especially in the disadvantaged areas that are production centers of secondary crops used as raw materials for biomass energy (unescap-capsa, 2008). the un fao 2007 forest report states: “deforestation and forest degradation will continue in most developing regions; a reversal of the situation would depend on structural shifts in economies to reduce direct and indirect dependence on land. in most developing tropical countries, agricultural land used for both subsistence and commercial cultivation continues to expand. consequently, loss of forests will vlosky & smithhart/journal of tropical forestry and environment vol. 01, no. 01 (2011) 1-13 9 journal of tropical forestry and environment vol. 01, no. 01 (2011)1-13 continue.” “while heating and cooking will remain the principal uses for fuelwood and charcoal in developing countries, the use of solid biofuels for the production of electricity is expected to triple by 2030” (un fao, 2007). “wood energy could become a motor for the development and expansion of forestry activities. progressive policies are required to ensure that these changes help alleviate poverty in developing countries. … new energy and environmental policies are making wood fuel an essential ingredient of energy policy in both developed and developing countries. in developed countries, it is likely that the use of wood for energy will continue to increase. for many developing countries, wood will remain the most important source of energy. the rising price of oil and increasing concern for climate change will result in increased use of wood as fuel in both developed and developing countries” (un fao, 2007). these are very telling statements: “new energy and environmental policies are making wood fuel an essential ingredient of energy policy in both developed and developing countries”… and “increasing concern for climate change will result in increased use of wood as fuel in both developed and developing countries”. the environmental policies that are referred to are the anti-fossil-fuel policies, wherein the burning of wood is deemed preferable because it is “renewable biomass”. the fact that burning wood releases more greenhouse gases per unit of energy released than burning oil or natural gas does, is simply overlooked. the assumption is that the wood will be re-grown and absorb as much co 2 from the atmosphere as released in the burning. bioenergy production as heat, electricity, and liquid fuels represents about 14% of the world’s primary energy supply. about 25% of the usage is in industrialized countries and the other 75% is used in developing countries. the total sustainable worldwide biomass energy potential is about 100 ej/a (the share of woody biomass is 41.6 ej/a), which is about 30% of total global energy consumption today. about 40 ej/a of available biomass is used for energy. nearly 60% of this biomass is used only in asia. a comparison between the available potential with current use shows that on a worldwide level about two-fifths of the existing biomass potential is used, and in most areas of the world the current biomass use is clearly below the available potential. only in asia does the current use exceed the available potential. therefore, an increased biomass use is possible, e.g. for production of densified biofuels, in most countries (parikka, 2004). the total above-ground wood volume (m3) and woody biomass (tons) in forest has been estimated in 166 countries, representing 99% of the world’s forest area (table 1). the world’s total aboveground biomass in forests is 420 (109) tons of which more than 40% is located in south america and about 27% is in brazil alone (fao, 2001). biomass currently represents approximately 14% of world’s final energy consumption (iea, 1998). about 25% of the usage is in industrialized countries, where a significant level of investment in environmental protection has been made to meet emissions standards, especially air emissions (overend, in sayigh, 2002). the other 75% of primary energy use of biomass is in heat production for developing country household energy needs and in process heat production for biomass-based industries through the use of their generated (overend in sayigh, 2002). estimates of global potential for biomass that can be converted into fuels vary widely. one recent study concluded that by 2050, biomass theoretically could supply 65% of the world’s current energy consumption, with sub-saharan africa, the caribbean, 10 and latin america accounting for roughly half of this global potential (smeets et al., 2004). in tropical countries, high crop yields and lower costs for land and labor provide an economic advantage that is hard for countries in temperate regions to match (worldwatch institute, 2006). plans for increased biofuels production are also advancing in latin america (including colombia and peru), asia (india, thailand, malaysia),australia, africa (especially south africa but possibly also zimbabwe, madagascar, malawi, and mozambique), and eastern europe (romania, ukraine, and russia) (smeets et al., 2005). for example: • the indian government has identified nearly 100 million acres of land where jatropha can be grown as a biofuel and hopes to replace 20% of diesel consumption in five years (casey, 2006). • malaysia, the world’s top producer of palm oil, has approved licenses for 52 biodiesel plants with a combined capacity of 1.5 billion gallons a year (reuters, 2006). (however, the destruction of tropical forests for palm cultivation is a major environmental concern (friends of the earth international, 2004). • the australian government has set a target of producing nearly 100 million gallons of ethanol annually by 2010 (nash, 2005). biomass provides a surprisingly large amount of the world’s energy – 10% of total global primary energy consumption – but most of that is wood and charcoal gathered and used in the most primitive ways. sustainable biofuel development can help bring modern energy services to more people, particularly in rural areas. it can also foster greater investment in agriculture, which employs 75% of the world’s poor. it can create new job opportunities in rural areas and provide a major new source of income for farmers (roche and perez, 2006). by producing transportation fuel, farmers will be entering a market with higher prices and rising demand. growing energy crops is more likely to attract the kind of foreign investment that can modernize their agricultural practices – and increase their food production as well. the food and agriculture organization of the united nations notes these benefits as well: “energy plantations and crops (in particular perennial crops) can help to prevent soil erosion by providing a table 1. forest resources, above-ground biomass volume and biomass (m3 and tons) forest area volume volume woody biomass woody biomass (ha) (109) (m3/ha) (ha) (109) (tonne/ha) (tonne/ha) africa 649 72 46 109 70 asia 547 63 34 82 44 europe 1039 112 116 59 61 north and central america 549 123 67 95 52 oceania 197 55 10 64 12 south america 885 125 110 203 179 world 3869 100 386 109 421 fao, faostat-database 2002, http://ww.fao.org, 2002 fao, state of the world’s forests-2001, www.fao.org, 2001 vlosky & smithhart/journal of tropical forestry and environment vol. 01, no. 01 (2011) 1-13 11 cover which reduces rainfall impact and sediment transport. annual energy crops can also allow diversification and expansion of crop rotations. deforested, degraded and marginal land could be rehabilitated as bioenergy plantations which could combat desertification and increase food production.” (fao, 2005). bio-based energy in tropical countries tropical and subtropical forests comprise 56% of the world’s forests, while temperate and boreal forests account for 44% (fao, 2001). tropical countries enjoy favorable conditions for growing biomass. however, constraints to optimal use as an energy source are still to be resolved. the main issues are legal and institutional barriers, as well as a lack of information and technology transfer. furthermore, common misconceptions about biomass energy have to be redressed. it should be emphasized that the larger part of wood fuels comes from non-forest land; wood fuel use is not the root cause of deforestation; biomass energy is more than a traditional commodity; and biomass energy will not phase itself out in the foreseeable future. the tropical asian countries have a large potential for biomass production. it is expected that various projects of large-scale energy crop production (e.g. cassava, oil palm, sugar cane, etc.) will be implemented in the near future under the initiatives of both industrialized countries, through cdm schemes, and tropical asian countries themselves. for example, the government of indonesia will set a biofuel (bioethanol and biodiesel) target of about 10 per cent of the country’s energy portfolio by 2010. the government also expects the sector to create around 3 million jobs and cut foreign exchange expenditure for importing fuel by us$ 10 billion by 2010. to this end, the government will allocate 6.5 million ha of idle land for investors interested in planting energy crops. of the total land allocation, some 3 million ha will be allocated for oil palm, 1.5 million ha for jatropha, 0.5 million for sugar cane and 1.5 million ha for cassava (the jakarta post, 25 july 2006). references bain, r. l. 1993. electricity from biomass in the united states: status and future direction. bioresource technology 46 (1-2):86-93. bergman, p. c.a., and j. h.a. kiel. 2005. torrefaction for biomass upgrading. paper read at 14th biomass conference & exhibition, at paris, france. casey, michael. 2006. “across asia, governments look to crops to offset oil dependence,” associated press, may 1, 2006 (http://www.enn.com/today.html?id=10367). clair, lee. 2010. biomass – an emerging fuel for power generation lee clair, norbridge inc., february 24, 2010. http://www.renewableenergyworld.com/rea/news/article/2010/02/biomass-an-emergingfuel-for-power-generation) combs, s. 2008. the energy report. texas comptroller of public accounts. debell, d.s., c.d. whitesell, and t.h. shubert. 1989. using n2-fixing albizia to increase growth of eucalyptus plantations in hawaii. for. sci. 35:64-75. journal of tropical forestry and environment vol. 01, no. 01 (2011)1-13 12 dimitri, c., a. effland, and n. conklin. 2005. the 20th century transformation of u.s. agriculture and farm policy. edited by usda. washington, d.c. fao. 2001. fao. state of the world’s forests—2001, www.fao.org, 2001. fao. 2005. food and agriculture organization of the united nations, “bioenergy,” paper presented to the committee on agriculture, apr. 2005 (http://www.fao.org/docrep/meeting/009/j4313e.htm). fao. 2007. [ftp://ftp.fao.org/docrep/fao/009/a0773e/a0773e09.pdf] friends of the earth international. 2004. “greasy palms – palm oil, the environment and big business,” mar. 2004 (http://www.foe.co.uk/resource/reports/palm_oil_summary.pdf). fuglie, k. o. 2010. accelerated productivity growth offsets decline in resource expansion in global agriculture. edited by usda. hewett, c e, c j high, n marshall, and r wildermuth. 1981. wood energy in the united states. annual review of energy, november 9, 139-170. hoogwijk m., 2004, on the global and regional potential of renewable energy sources, utrecht university, department of science, technology and society, pp 256 iea. 1998. international energy agency (iea). world energy outlook, 1998 edition, www.iea.org, 1998. jackson, s., t. rials, a. taylor, j. bozell, and k. norris. 2010. wood2energy. edited by s. w. jackson. knoxville, tn: university of tennessee. kim, s., and b. e. dale. 2004. global potential bioethanol production from wasted crops and crop residues. biomass and bioenergy 26 (4):361-375. mathews, j.a. 2008. opinion: is growing biofuel crops a crime against humanity? biofuels, bioproducts and biorefining. volume 2, issue 2, pages 97–99, march/april 2008 meza, j., a. gil, c. cortes, and a. gonzalez. 2008. drying costs of woody biomass in a semi-industrial experimental rotary dryer. in 16th european conference exhibition on biomass for energy biomass resources. nash, fiona. 2005. “submission to biofuels taskforce,” july 1, 2005 (http://www.dpmc.gov.au/biofuels/ submissions/submission54.pdf). overend rp. bioenergy production and environmental protection. in: sayigh a, editor. workshop proceedings, world renewable energy congress, june 29–july 5. germany: cologne; 2002. parikka, m. 2004. global biomass fuel resources. biomass and bioenergy 27 (6):613-620. perlack, r. wright, l., turhollow, a., graham, r., stokes, b., erbach, d. 2005. biomass as a feedstock for a bioenergy and bioproducts industry: the technical feasibility of a billion-ton annual supply. edited by d. o. energy. oak ridge, tennessee: doe. powlson, d.s., a.b. riche, and i. shield. 2005. biofuels and other approaches for decreasing fossil fuel emissions from agriculture. annals of applied biology 146:193-201. prins, m. j., k. j. ptasinski, and f. j.j.g. janssen. 2006. more efficient biomass gasification via torrefaction. energy 31 (15):3458-3470. reuters. 2006. “malaysia approves 52 biodiesel plants so far,” reuters, aug. 16, 2006 (http:// www.planetark.com/dailynewsstory.cfm/16-aug-2006/story.htm). roche, kathy and teresita perez. 2006. “our addiction to oil is fueling world poverty,” center for american progress, apr. 6, 2006 (http://www.americanprogress.org/site/ pp.asp?c=bijrj8ovf&b=1533171). vlosky & smithhart/journal of tropical forestry and environment vol. 01, no. 01 (2011) 1-13 13 saidur, r., e. a. abdelaziz, a. demirbas, m. s. hossain, and s. mekhilef. 2011. a review on biomass as a fuel for boilers. renewable and sustainable energy reviews 15 (25x25):2262-2289. slovak non-profit organizations. 2011 .http://www.seps.sk/zp/fond/dieret/biomass.html smeets, edward, andre faaij and iris lewandowski. 2004. “a quickscan of global bio-energy potentials to 2050,” copernicus institute, mar. 2004, p. 2 http://www.chem.uu.nl/nws/www/publica/e2004109.pdf). smeets, edward, martin junginger, and andré faaij. 2005. “supportive study for the oecd on alternative developments in biofuel production across the world,” copernicus institute, dec. 2005 (http:// www.chem.uu.nl/nws/www/publica/publicaties2005/e2005-141.pdf). stuart, b., and l. grace. 2009. wood in design and engineering. starkville, ms, fall 2009 the jakarta post. 2006. 25 july. u.s.d.a. president obama issues presidential directive to usda to expand access to biofuels 2009 (cited 12/14/2010). available from oc.news@usda.gov. u.s.d.o.e. 2008. primary energy consumption by source, selected years, 1949-2008. us department of energy. u.s.d.o.e. 2008. u.s. department of energy: energy efficiency and renewable energy. u.s.d.o.e. 2010. biomass multi year program plan. edited by office of the biomass program: energy efficiency and renewable energy. unescap-capsa. 2008. impact analysis of expanding biomass energy use to rural poverty in tropical asia/ by masdjidin siregar and tomohide sugino. bogor; unescap-capsa, 2008. xiv, 61 pp.; 23.8 cm. — (working paper series; no. 103) westscott, p.c. 2007. ethanol expansion in the united states: how will the agricultural sector adjust? edited by u.s.d.a.: e.r.s. world energy council. 1997. bulletin d’information. issue 3, march 1997. worldwatch institute. 2006. “biofuels for transportation,” extended summary, june 7, 2006, p. 6 (http:/ /www.worldwatch.org/taxonomy/term/445). wto. world trade organization. 1999. extracted from world food summit fact sheet the role of forests in food security). third wto ministerial conference. seattle, 28 november-3 december 1999 zhu, j. y., and x. j. pan. 2010. woody biomass pretreatment for cellulosic ethanol production: technology and energy consumption evaluation. bioresource technology, 4992-5002. journal of tropical forestry and environment vol. 01, no. 01 (2011)1-13 ranasinghe /journal of tropical forestry and environment vol. 12, no. 01 (2022) 1-9 1 feature article carbon net-zero by 2050: benefits, challenges and way forward hemanthi ranasinghe1* 1department of forestry and environmental science, university of sri jayewardenepura, sri lanka abstract in accordance with the paris agreement, to which sri lanka is a party to, global temperature rise must be kept well below 2°c relative to pre-industrial levels and efforts to limit the temperature increase to 1.5oc above pre-industrial level must be pursued. in response to this, countries who signed the unfccc, including sri lanka, submitted their nationally determined contributions (ndcs) in 2016 which will come into force during 2021-2030. however, according to emissions gap report 2021 (unep 2021), climate pledges combined with other mitigation measures put the world on track for a global temperature rise of 2.7°c by the end of the century which is above the goals of the paris climate agreement which intended to keep the global temperature rise well below 2°c. therefore, in order to address this alarming situation, many countries including sri lanka have given pledges to become carbon neutral by 2050. this means that the emissions from economic sectors will be reduced as per the ndc scenario and even beyond while increasing the carbon sequestration. in this equation, plants play a unique role as they are the only organisms which can absorb atmospheric carbon dioxide in the photosynthesis function. according to the third national communication of sri lanka, forests/trees will contribute to 11.5% of the green house gas (ghg) emission reduction which is projected by all sectors in the country by 2030. it is required to increase this contribution to a much higher level in order to achieve carbon neutral status. in this context while drastically reducing the deforestation almost to zero, it is required to increase the tree cover in the country including natural forests and trees outside forests which includes home gardens, urban forests and avenue plants, coconut plantations, shade trees in tea lands etc. keywords: climate change, green house gas, net-zero, carbon-neutral, forestry 1. what is net-zero net-zero has become the rallying cry for the fight against climate change. it represents a viable target that scientists agree is necessary if the world is to avoid the most dramatic impacts of climate change. the idea of net-zero is often oversimplified, but in reality, it has many nuances and can be challenging to achieve. net zero status can be achieved by balancing emissions of carbon dioxide with its removal or by eliminating emissions from society. we must reach net-zero by 2050 in order to meet the global net-zero target of limiting warming to 1.5°c by 2100. it requires bold climate action to limit global warming. adoption of net zero by 2050 move is a crucial and timely requirement to implement nationally determined contributions (ndcs) submitted by the parties to the paris agreement for mitigating the greenhouse gas emissions that cause climate change and for adapting to climate impacts. before industrialization, the global environment had enough carbon sinks, or areas that would capture carbon dioxide emissions, to balance its natural production of greenhouse gases. *correspondence: hemanthi.ranasinghe@gmail.com tel: +94714478756 issn 2235-9362 online ©2022 university of sri jayewardenepura ranasinghe /journal of tropical forestry and environment vol. 12, no. 01 (2022) 1-9 2 this is causing environmental degradation in natural systems and leading to widespread climate change. as a result, global governments are working together to limit warming and reach net-zero carbon emissions. the transportation and energy sectors are the main targets for these policies because they account for a majority of carbon emissions (iea, 2021). however, this change is happening in every aspect of the economy. to achieve net-zero emissions by 2050, serious action needs to be taken now. the global transition towards low carbon was already off track many decades ago. now, we need ambitious policies and pledges to help shift the trend. infrastructure needs to be built, economies need to be overhauled, and supply chains and industries that have not been changed in decades must be optimised. net-zero is a win-win solution, an ambitious goal, and it requires collaboration and strong action. whether the world is up for the deployment challenge is an open question. a wave of countries pledged to go net zero following the paris agreement. according to the international energy agency these commitments of the countries now cover 70% of global emissions, and yet they still fall short of what is needed to limit warming to 2oc by 2100. they reiterated that even if the pledges made were successfully implemented, it would leave roughly 22 billion metric tons of co2 emissions in 2050, resulting in a temperature rise of roughly 2.1oc. global emissions from fossil fuels were 34 billion metric tons in 2020. while it’s useful to have this scenario on how we could reach a 1.5oc target, it is important to emphasize that it is going to be a huge lift and will require much more political will by countries all around the world than has been evidenced to date (iea, 2021). 1.1 how to achieve net zero status? according to un, if everyone had access to clean, affordable energy, the road to a carbon neutral world – net zero emissions by 2050 – would be faster as energy production and consumption is the highest emitter of ghgs to the atmosphere. un had launched a roadmap for clean energy transition during cop 26 climate change conference in 2021 held in the uk. by 2025, the roadmap envisage that investments in the order of $35 billion and $25 billion needs to be invested into improving access to electricity and clean cooking, respectively. the roadmap also calls for subsidies for fossil fuel consumption to be re-directed towards renewable energy and energy efficiency. the world’s annual investment in renewables and energy efficiency must over the same time frame. it also emphasized that by 2030, the coal power plants be phased out completely for member countries of the organization for economic co-operation and development (oecd), and phased out globally by 2040 (koons, 2022). some of the other important milestones in this journey are; increase the share of electric automobiles since still it accounts for 5% of global automobile sales and it will need to represent 60% of new automobile purchases in 2030, increase the share of annual renewable installations, which hit a record 280 gigawatts last year, will need to exceed 1,000 gw. the global roadmap aims to achieve sustainable development goal 7 – one of 17 sustainable development goals established by the un general assembly in 2015. it pledges to “ensure access to affordable, reliable, sustainable and modern energy for all” by 2030. 1.2 net-zero in asia asia’s economic success over the past 5 decades has been coupled with remarkable achievements in reducing poverty and improving the quality of life. but the region’s economic growth has also resulted in a significant increase in global warming greenhouse gas emissions. asia’s share of worldwide emissions increased from 8.7% in 1973 to 28% in 2010, and is expected to increase to 40% by 2030 if present industrial production and energy consumption growth rates continue (adb, 2015). asia needs to switch to a less polluting pattern of production and consumption while maintaining the growth and social development it requires. energy consumption, the burning of fossil fuels in particular, is the main source of human-induced greenhouse gas emissions—the main cause of climate change. but energy is also a fuel for growth, particularly for the rapidly developing economies of asia. the challenge ranasinghe /journal of tropical forestry and environment vol. 12, no. 01 (2022) 1-9 3 for developing asia is to maintain economic growth while reducing the carbon content of energy and increasing the efficiency of resource use. the way in which asia manages its future developmental activities in a low-carbon resource-efficient way is critically important, as the world increasingly looks to asia for its growth. asia can also be a model for measures to mitigate climate change. in achieving low carbon growth, pricing, including carbon taxes, tradable emission permits, incentives for climate friendly technology innovations, standards, and regulations—all of these instruments are helping emerging economies to tackle climate change and accelerate green growth. however, an effective economic strategy to deal with climate change is not only about identifying the best tools; above all it is about combining and deploying the various available instruments in a coherent way. low-carbon green growth in asia demonstrated that asia has already started doing this to meet individual developmental needs while still achieving the overall objective of ambitious emission reductions. while these policies are replicable and can be scaled up, better regional cooperation is clearly needed (adb, 2015). 1.3 net-zero in sri lanka sri lanka is a small island nation located in the indian ocean with a physically diverse geography and tropical climate. total land area is about 65,610 square kilometers and a total population of the country is 21.7 million. being a topical island nation, sri lanka has been identified as a highly vulnerable country to the adverse effects of climate change such as temperature rise, rainfall variability, extreme weather events and sea level rise critically affecting almost all the economic sectors of the country. occurrences of natural disasters due to extreme weather events such as prolonged droughts, flash floods and landslides deprive lives and livelihoods of people. sri lanka was ranked in 4th, 2nd and 6th positions as a most vulnerable country in 2016, 2017 and 2018 respectively according to the global climate risk index. about 74 percent of disasters took place between 1990 2018 were due to adverse impact of climate change, such as floods (58%), landslides (5%), storms (7%), and drought (4%). damage due to flooding between 1990 2018 was estimated over usd 2 billion and half of which occurred in 2016 (moe, 2022). the damages occurred in many sectors, namely, human settlements, health and nutrition, education, food security (agriculture, livestock and fisheries), industry and commerce, irrigation, water and sanitation, transport, power supply, employment and livelihood, and environment. disaster risk in sri lanka is now mainly due to hazards and climate change. flooding remains as the key hazard in many parts of the country. similarly, droughts have had widespread adverse impacts over the country in 2016 – 2017. the drought experienced in 2016 -2017 which was considered to be the worst such event in the past 40 years (moe, 2022). over the last decade, the country has shifted from a predominantly rural-based economy to an urban-based economy, geared towards manufacturing and services. the resulting economic growth has led to an increased demand for energy investment and use, which in turn has led to increased air pollution, ghg emissions, and growing economic vulnerability to volatile fossil fuel supplies and prices. the country had seen a steady growth in ghg emissions in several sectors. according to sri lanka’s third national communication on climate change to the unfccc, the energy sector represented the largest share of total national ghg emissions 83% in 2016. this comprised of non-renewable power generation (electricity), transport and industry. the agriculture sector comprising paddy cultivation and livestock represented 8% each of the total emissions. this was followed by the ippu (industrial processes and product use) 4% and waste (moe, 2022). sri lanka has taken several positive steps to response to challenges posed by climate change. despite the fact that its ghg emissions is about 0.05% of the total ghg emissions in the world, it has committed to reduce the ghg emissions substantially by adhering to the paris agreement by submitting nationally determined contributions to include targets for reducing ghg emissions focusing on seven priority sectors, namely; energy, transport, industry, waste, forestry agriculture and livestock which include 4% unconditional and 10.5% conditional with respective to business-as-usual (bau) scenario ranasinghe /journal of tropical forestry and environment vol. 12, no. 01 (2022) 1-9 4 during the period of 2021-2030. it has introduced national policies, strategies and actions plans such as the national climate change policy of sri lanka (2012), national climate change adaptation strategy for sri lanka in 2010, technology needs assessment and technology action plans for climate change adaptation and mitigation in 2014, the national adaptation plan (nap) and nationally appropriate mitigation actions (nama) for energy and transport in order to address climate change induced impacts. it also has committed to make sri lanka carbon neutral by 2050 to support the commitments of the ndcs. with regard to the net zero drive, the country has prioritized the sectors to work on which are the most damaging in terms of ghgs. they are energy sector, transport sector, industry sector, waste sector and agriculture, forestry and other land use sector. in general the following directives had been identified across all the sectors; • promote low carbon technologies in all economic sectors through technology transfer and development. • promote low carbon technologies in all economic sectors through technology transfer and development. • to build the capacity of key economic sectors and relevant institutions to address low carbon development pathways and promote green jobs. the more sector specific directives towards carbon neutral status based on the low carbon development strategy sri lanka by the ministry of environment (unpublished) are shown as follows; 2. energy sector introduce new policies and policy supportive measures: mainstream low carbon measures in to national planning and development in energy sector; introduce policy supportive measures such as tax benefits, low-interest national and international financing to expedite the implementation of renewable energy development and energy efficiency improvement programmes. improve energy efficiency and energy conservation: improve demand side management and supply side management measures by promoting energy-efficient equipment; new technologies, and system improvements in a national energy efficiency improvement and conservation programme; transmission and distribution network efficiency improvement; reducing energy demand through lifestyle changes. promote energy diversification: enhance renewable energy contribution to the national electricity generation mix by increasing solar pv, wind, hydro and sustainable biomass-based electricity generation; facilitate the implementation of pilot scale project by using new renewable energy sources; convert existing fuel oil-based combined cycle power plants to use natural gas and to develop new natural gas plants as alternative to planned coal power plants. build an enabling environment for energy development: strengthen technology innovation and environmental protection as a means to set up a stable, economic, clean and safe energy system; strengthen the implementation of various laws and regulations on renewable energy. promote carbon capture and storage: develop national carbon emission standards; engage in viable carbon trading mechanisms to promote the shift towards renewable energy sources; set up carbon funds to promote investment in low carbon and development. use of technology, research and development: promoting investment in research and development for technological innovation and increasing public research development and deployment in innovative clean energy technologies; develop stronger collaborative partnerships with the private sector on largescale research development and deployment projects. ranasinghe /journal of tropical forestry and environment vol. 12, no. 01 (2022) 1-9 5 3. transport sector introduce new policies and policy supportive measures: introduce new national policy or improve/ amend relevant existing policies to promote low carbon sustainable transport modes; introduce carbon pricing instruments (carbon tax/emission trading system) for reduce ghg emission and enhance the trend of carbon market. establishment of energy efficient and low carbon sustainable transport systems: improve traffic light management; improve parking management; introduce intelligent transport management system: shift fright to efficient modes. promote public passenger transport and well managed public transportation network: rapid transport for passenger transport; encourage and foster the use of non -motorized transportation; encourage increasing investment into public transport; improve road and railway transport infrastructure and facility; develop and improve walking and cycling infrastructure; making island water transport modes more attractive for users; enhance park and ride system; improve last mile connectivity. management of fuel quality standards (fqs) of vehicles: manage the fqs to minimize environmentally harmful emission and improvement of energy efficiency in vehicles; reducing carbon intensity of fuels by substituting petroleum-based products by low carbon/zero carbon emission fuels (natural gas, biofuel etc;). encourage and promote electric mobility and low emission hybrid vehicles: encourage and promote to use of electrified or hybrid vehicles; facilitate the infrastructure development for use of those vehicles and increase tax concessions for electrical and hybrid vehicles. improve vehicle fleet efficiency: improve efficiencies of existing vehicle fleet; promote the import of fuel-efficient vehicles; introduce programmes to change driver behaviors. change life styles for avoiding/reducing travel: encouraging teleworking, and remote working and further promotion of government online services as a means to reduce and avoid the need to travel specially to and from specific ‘traffic hotspots’, and during peak hours; (in this strategy consider the teleworking/ remote working possibility as a ghg reduction measure, addressing the dependency of productivity and transport. in order to support this further, government will be looking into promoting and incentivizing further remote working amongst the workforce and the enhancement, improved provision of online services). modernizing and upgrading of suburban railway and road infrastructure development: electrification of railway lines; develop new railway lines and expansion of existing railway network; development of provincial and rural road infrastructure for improved mobility; expansion of expressway network. improve the marine transportation system: promote sea transportation; introduce energy efficient measures for coastal shipping and fishing vessels. 4. industry sector introduce new policies and policy supportive measures: introduce new national policy or improve/ amend relevant existing policies to promote low carbon sustainable industries. promote clean and green energy sources and fuel switching technologies: continue fuel-switching to sustainable biomass energy and improve user efficiency in selected appropriate industries/industrial subsectors; develop and promote clean and green energy efficient production technologies. ranasinghe /journal of tropical forestry and environment vol. 12, no. 01 (2022) 1-9 6 enhance cleaner production practices: enhance the application of resource efficient cleaner production (recp) practices in selected industrial sub sectors by promoting energy efficient appliances and technologies such as high-efficient motors, variable frequency drives, efficient chillers & refrigeration technologies; adopting low carbon recp technologies and process. promote green evaluation systems: promote green purchasing; carbon footprint calculations in industries; green awarding; national green reporting system. establish eco-industrial parks and villages and introduce tri-generation facilities to selected industrial parks: transform existing industrial parks (ips) incorporating maximum possible green industrial concepts; introduce policy and regulatory regime; including guidelines to ensure all new ips will be set up as eco ips. introduce circular economy concept to selected industrial sub-sectors and selected industrial zones: introduce the life cycle approach for greening the supply chain (minimizing transport distances, organic farming etc.); practice industrial symbiosis concept for industrial parks and industrial sub-sectors; promote zero-waste concept in industrial parks or industrial subsectors. build an enabling environment for low carbon industrial sector: promote national green reporting system (ngrs); enhance the availability of sustainable biomass for industry use; facilitate transformational investment and favorable loans through financing institutions linking with green financing; promote green procurement system: facilitate adopt relevant iso systems having a focus on ghg emission reduction. 5. waste sector introduce new policies and policy supportive measures: introduce new national policy or improve/ amend relevant existing policies to promote the integrated sustainable waste management to achieve the target of waste free country. improve “circular economy’’ practices in solid waste generation sources: facilitate for the proper waste management to minimize of waste production in industry, government, public and tourists by promoting 3r concept; economic incentives to promote repair and reuse activities; digitize office procedures; exploring economic incentives targeting recycled materials in construction. promote a source separation system at the household level and implement a proper collection mechanism: improve solid waste segregation; collection mechanism and transportation system; implement regulatory framework to control high waste generating products. use of biodegradable waste for production of organic fertilizers: limit land filling to non-recyclable, non-compostable and inert material generated through waste treatment processes and improve the compost preparation system for each local authority to manage organic waste. enhance and promote energy generation by waste: introduce energy generation by waste form mechanisms such waste to energy. manage industrial/hazardous and clinical waste in a systematic way: establish institutional mechanisms to prevent hazardous biomedical/healthcare waste entering into the municipal waste management system and into sri lanka. build an enabling environment for sustainable and low carbon waste management: introduce a mechanism for waste generation forecasting with a tracking system to monitor the generation; introduce legislation to make segregation of waste at household level mandatory; implement “polluter pays ranasinghe /journal of tropical forestry and environment vol. 12, no. 01 (2022) 1-9 7 principle” for mixed waste generators; establish a set of waste prevention guidelines for all functional events; introduce legislation to prohibit the use of single-use plastics in public events (this measure can be introduced for single-use plastic items that are not already banned); amend the building regulations to mandate a minimum of 10%-15% recycled materials in buildings; setting up a waste prevention budget line to incentivize waste prevention initiatives; provide economic incentives to support society in transitioning towards voluntary prevention and reuse initiatives; provide economic incentives to support society in transitioning towards voluntary prevention and reuse initiatives; create new business opportunities for greener products, repair services and secondary markets. increase community awareness and motivate to produce less domestic waste: foster a culture of resource efficiency by encouraging alternative choices that contribute towards sustainable consumption; changing attitudes towards preventing unnecessary use; and encouraging the repair and reuse of items rather than discarding them early in their economic lifetime. 6. agriculture, forestry and other land use 6.1 agriculture and livestock sector reduce post-harvest losses at every stage: reduce post-harvest losses at field stage, transportation and delivery end; promote value addition for fruits and vegetables; promote/develop post-harvest management with environmentally friendly packages; introduce proper waste management practices for agricultural waste; promote to use of crop residues and postharvest losses for production of organic fertilizer. promote use of organic fertilizer, pesticides and weedicides: aware the farmers use of excess amount of chemical fertilizer and promote to use of organic fertilizer/bio fertilizer which will improve the soil fertility; develop the market for organic food products. promote integrated pest management (ipm) practices: introduce environmentally friendly biodegradable/bio pesticides and biocontrol agents for ipm. increase the crop production of unit land area to minimize the land use: promote good agricultural practices (gap); introduce high yield verities; promote heat, drought, flood and salt tolerant varieties; improvement water use efficiency. reduce food milage to ensure the use of low carbon food products: promote home gardening and introduce new technologies to cultivate different crop verities; develop and facilitate railway system for transportation of vegetables, fruits and other food products; encourage/promote use of unprocessed food at always. promote use of renewable energy in agricultural and livestock activities in all possible measures: use of solar pv and wind energy for agricultural practices; explore and develop small hydro power potential in irrigation water canals for agriculture purpose. 6.2 forestry and other land use sector increase forest cover of sri lanka up to 32% by 2030: identify the lands and degraded lands and promote afforestation, reforestation and forest restoration. reduce deforestation and forest degradation: promote reduction of emissions through deforestation and forest degradation; support household energy plantations to reduce pressure on natural forests; promote sustainable management of forests and lands to reduce forest degradation. ranasinghe /journal of tropical forestry and environment vol. 12, no. 01 (2022) 1-9 8 improve quality of growing stock of natural forests and forest plantations: improve the quality of growing stock of degraded forests and forest plantations. increase river basin management for major rivers of sri lanka: multi hazard prioritization of catchment or river basins; strengthen catchment protection of cascade systems & isolated tanks through tree planting. promote growing trees outside the forests (trees outside forests -trof) to increase the tree cover: promote urban forestry, tree planting along roadside, religious premises, schools and other government lands, home gardens. introduce and facilitate for the result based payments for conservation of the forests: develop or setup national forest monitoring system (nfms), forest reference level (frl), monitoring, reporting and verification (mrv) system and safeguard information system (sis) for fulfill the requirement for result based payment. 8. key challenges and issues facing a low-carbon society establishing a low-carbon society poses a number of policy challenges and difficulties for emerging and low-income economies. many studies indicate that significant potential for emission reductions exists in all economies in the order of 25% 27% per sector (adb–adbi 2013), of which only a fraction has been achieved so far. the carbon intensity of developing asia remains 1.4 4 times greater than that of the g7 industrialized countries. the opportunities available for a low-carbon society have remained largely unexploited because of scientific, economic, and geopolitical uncertainties about the following; • domestic and international access to financial resources; • the nature, timing, and extent of local biophysical impacts as a result of climate response; • the development and costs of new technologies that will reduce reliance on carbon-intensive processes; and • the level of ambition and the likelihood of international cooperation to reduce carbon emissions the net zero emissions by 2050 scenario calls for profound transformations in the country’s economy that is both decarbonized and able to support a economy which may be twice the size of today’s in 2050. despite the policies, plans, technological and other interventions, net zero emissions in 2050 cannot happen without the consent and active support of people. in part, this involves one-off events that are not counted as behavioral changes but involve a mixture of low carbon technologies and people’s engagement, however, behavioral changes – meaning adjustments in everyday life that reduce wasteful or excessive energy consumption – are also needed. many developing countries in the region including sri lanka have committed themselves politically to low-carbon society objectives but many have yet to match this with the necessary policy actions and financial allocations. however, it is apparent that this is a win: win situation for all and it is imperative to find solutions to the aforesaid challenges by way of policy, strategy, action plans, bi lateral and multi-lateral cooperation, technology transfers, provide easy access to international green funds etc. as soon as possible in order to realize the positive benefits of moving towards carbon neutrality. references adb and asian development bank institute (adbi). 2013. low-carbon green growth in asia: policies and practices. tokyo: adbi. lohani, b.n., kawai, m. and anbumozhi, v. eds., 2016. managing the transition to a low-carbon economy: perspectives, policies, and practices from asia. brookings institution press. ranasinghe /journal of tropical forestry and environment vol. 12, no. 01 (2022) 1-9 9 dhyani, s., karki, m. and gupta, a.k., 2020. opportunities and advances to mainstream nature-based solutions in disaster risk management and climate strategy. in nature-based solutions for resilient ecosystems and societies (pp. 1-26). springer, singapore. hewawasam, v. and matsui, k., 2019. historical development of climate change policies and the climate change secretariat in sri lanka. environmental science & policy, 101: pp.255-261. ministry of environment 2021b., updated nationally determined contributions, sri lanka. unep., 2021 emissions gap report 2021: https://www.unep.org/resources/emissions-gap-report-2021 ministry of environment., 2021 low carbon development strategy sri lanka (draft), sri lanka. ministry of environment., 2022 third national communication of climate change in sri lanka, sri lanka, sri lanka. marteau, t.m., chater, n. and garnett, e.e., 2021. changing behaviour for net zero 2050. bmj, 375. koons, e. 2022., net-zero by 2050: humanity’s best bet against climate change, energy tracker asia. bouckaert, s., pales, a.f., mcglade, c., remme, u., wanner, b., varro, l., d'ambrosio, d. and spencer, t., 2021. net zero by 2050: a roadmap for the global energy sector. https://www.unep.org/resources/emissions-gap-report-2021 24 comparative analysis of hexavalent chromium biosorption efficiency using dead and live aspergillus nomius biomass s. guha, s. debnath, s. gayen* department of microbiology, vijaygarh jyotish ray college, kolkata-700032, west bengal, india date received: 10-11-2021 date accepted: 23-12-2021 abstract daily industrial activities especially in developing countries produce and discharge wastes containing heavy metals into the water resources making them polluted, threatening human health and the ecosystem. one such heavy metal is chromium, the hexavalent form of which is extremely toxic and carcinogenic. biosorption, the process of passive cation binding by dead or living biomass, represents a potentially cost-effective way of eliminating toxic heavy metals from industrial wastewater. the potential of microorganisms to remove metal ions in solution has been extensively studied; in particular, live and dead fungi have been recognized as a promising class of low-cost adsorbents for the removal of heavy metal ions. fungal biomass has various advantages; hence, it needs to be explored further to take its maximum advantage in wastewater treatment. in this study, we discuss the live and dead fungi characteristics of sorption, factors influencing heavy metal removal. biosorption studies were performed with both dead and live biomass and the effectiveness of cr (vi) biosorption was compared for each parameter. it was observed that biosorption was maximum (approximately): 82% while using sulfuric acid as the pre-treatment agent (hence only dead biomass) and also maximum of 96.5% at 1 n. the optimum ph for maximum biosorption was 6 when dead biomass was used, while it was 2 when live biomass was used. maximum chromium removal of 86% was obtained using 2 g live biomass whereas 0.5 g of dead biomass was enough to obtain the maximum efficiency.96% chromium was removed at 25° c using dead biomass, whereas, maximum removal of about 84% was obtained when live biomass was used for biosorption and it took place at 35° c. maximum cr (vi) removal of about 95% was obtained when dead biomass was used and 69% when live biomass was used, both at 1mg/l metal concentration. 0.5 g of dead biomass in 100 ml, 1 mg/l solution, was optimum for cr (vi) removal, while for live biomass, maximum cr (vi) biosorption of 63% was obtained when 1.5 g of it was used in 300 ml solution. it was finally concluded that dead fungal biomass has better biosorption potentials and also some other inherent advantages over live biomass. keywords: biomass, biosorption, fungi, heavy metal, hexavalent chromium 1. introduction water bodies getting contaminated by heavy metals is becoming a great global concern. heavy metals reach the environment through two main sources, natural (volcanic emissions, forest fires, deepsea vents, and geysers) and anthropogenic (mining and smelting sites, tanneries, metal-manufacturing plants, and painting and coating industries). industrial expansions lead to an uncontrollable release of heavy metals in the environment. the problem is primarily observed for developed countries that produce huge quantities of waste-waters,that may contain a high concentration of heavy metals. due to the lack of technologies, advanced manpower, and low policy enforcement, the challenge is stronger in developing countries. (gadd, 2009; singh and gauba, 2014; irawati et al., 2016; lata et al., 2019). *correspondence: tel: +94714877303 © university of sri jayewardenepura guha et al. /journal of tropical forestry and environment vol. 11, no. 02 (2021) 24-36 25 chromium, the heavy metal can exist in hexavalent as well as in trivalent forms. the hexavalent form is very toxic, carcinogenic, and mutagenic in humans and animals but the trivalent form is comparatively less toxic, less soluble and thus a lesser hazard (philip et al., 1998). various adverse health effects can result from hexavalent chromium exposure, including growth inhibition, cancer, nervous system damage, organ damage, and in extreme cases, death (akpor and muchiem, 2010). various conventional methods have been used to remove these contaminants from water bodies including filtration, chemical precipitation, ion exchange, reverse osmosis, evaporation, membrane technology, carbon adsorption, electrowinning, preconcentration, coagulation of wastewater, chelation, redox, and electrochemical treatment (yahaya and don, 2014; cai et al., 2016; jin et al., 2018; joshi, 2018; ferreira et al., 2019; khan et al., 2019). it has been concluded by many researchers, that these technologies have certain limitations on cost-effectiveness, cause of secondary pollution, complexity, and alteration of the physical and chemical nature of the environment. these techniques are usually very expensive for usage at a large scale and also tedious for constant monitoring and controlling, due to their incomplete and unpredictable metal removal efficiencies (ferreira et al., 2019; ayete et al., 2021). the above processes may also remove non-target useful microbial biota such as nitrogen-fixing bacteria as well as other fauna species which is undesirable (siddiquee et al., 2015). for overcoming those limitations, biological treatment (bioremediation) techniques are highly recommended because they are environmentally friendly, fast, and cost-effective (javanbakht et al., 2014; joshi, 2018; ferreira et al., 2019; ayete et al., 2021). these biological methods can also be implemented for treating a large volume of effluent with low biomass concentration within a short operation time (sharma et al., 2016). most common bioremediation techniques include biofilters, biosorption, bioaugmentation, bioventing, biotransformation, composting, land farming, bioreactor, and biostimulation. biosorption is one of the biological techniques that utilize microbes as a biosorbing agent to detoxify and remove environmental pollutants such as heavy metals (siddiquee et al., 2015). microbes uptake heavy metals through two processes, intracellular accumulation through their living biomass, and extracellular binding, through both living and dead biomass (kapoor, 1998; gadd, 2009; javanbakht et al., 2014). the filamentous fungal strains are of great interest for biotechnological applications such as wastewater treatment because they have some polymers in the structure of their cell wall which are responsible for the adsorption of pollutants (silah and gul, 2014). this study aims to investigate the biosorption potential of living and dead biomass of aspergillus nomius isolated from tannery effluent for chromium (vi) at a batch-scale level to assess its application as a low-cost biosorbent. 2. materials and methods 2.1 microorganism sixteen fungal strains (s1-s16) were isolated from tannery effluent of bantala leather complex area (kolkata, west bengal, india) and their cr (vi) tolerance capacity was tested at concentrations of 1,000-2,000 mg/l. among the 16 strains, s12 showed the maximum cr (vi) tolerance capacity of 2,000 mg/l and so this strain was subjected to fungal its sequencing analysis and phylogeny which revealed that the s12 strain has 99.82% similarity with a. nomius. (guha et al., 2020). so this s12 strain is being selected here for the biosorption study and it will be referred to as a. nomius. the strain is maintained on a czapekdox agar medium with regular subculturing after every 15 days and preserved at 4° c. 2.2 biomass production the fungus was cultured in a liquid medium (czapekdox broth) in 100 mm glass petri-plates. the growth medium consisted of (g/l of distilled water): sucrose 30.000, sodium nitrate 2.000, dipotassium phosphate 1.000, magnesium sulfate 0.500, potassium chloride 0.500, ferrous sulfate 0.010. 26 the ph of the medium was adjusted to 5, before autoclaving by using 0.5 m hcl. once inoculated, the plates were incubated in an incubator for 2 weeks at 30° c. for the production of sufficient fungal mat. 2.3 bio-sorbent preparation the dead and live biomass of a. nomius was used as a biosorbent for the sorption of cr (vi) from an aqueous solution. after incubation, the biomass was collected from the medium and washed with warm distilled water. to make it dead the biomass was then pre-treated by immersing it in 500 ml 0.5 (n) solutions of various acids and alkali (sulfuric acid, hydrochloric acid, nitric acid, acetic acid, and sodium hydroxide) and then kept in a water bath at 100° c for 15 minutes. for experiments with live biomass this pretreatment step was skipped (the biomass was only washed with cold water). the biomass was then washed with deionized water until the ph of the wash solution was in the nearneutral range (ph 6.8-7.2). it was then dried at 60° c in a hot-air oven for 12 hours, grounded using mortar and pestle, and stored in an air-tight container (santhi and guru, 2014). 2.4 chromium (vi) solution preparation aqueous (stock) solution of chromium (vi) concentration 1,000 mg/l was prepared by dissolving 2.83 g of potassium dichromate salt in 1,000 ml distilled water (reya et al., 2012). the concentration of chromium was varied from 1 mg/l to 5 mg/l. 3. optimization of various biosorption parameters 3.1 effect of pre-treatment (for dead biomass) fungal biomass was modified by pre-treatments with acids and alkali. 0.5 n, 500 ml solutions of sulfuric acid, hydrochloric acid, nitric acid, acetic acid, and sodium hydroxide were used for this purpose. the percentage removal of the metal ion with this pre-treated fungal biomass was studied spectrometrically at 540 nm using diphenylcarbazide (dpc) assay method (usepa, 1992). 3.2 effect of pre-treatment agent concentration (for dead biomass) the effect of pre-treatment agent concentrations was observed for biosorption of 1 mg/l of cr (vi) using different concentrations of sulfuric acid as pre-treatment agent (0.3, 0.5, 0.8, and 1 n). the adsorbent dosage was 0.5 g in 100 ml solution in 250 ml conical flask and ph 6.0. the flasks were then incubated for 24 hours at 37° c and 150 rpm. after 24 hours, the samples were taken out, filtered, and analyzed using dpc assay at 540 nm (reya et al., 2012). 3.3 effect of ph (determined with both dead and live biomass) the effect of ph on biosorption efficiency was determined using both live and dead a. nomius biomass. 100 ml of 1 mg/l concentration of chromium solution was adjusted to various ph (2, 4, 6, 8, 10, and 12), and to it, 0.5 g of biomass was added and incubated at 37° c, at 150 rpm for 24 hours. after 24 hours, the samples were taken out, filtered, and analyzed using dpc assay at 540 nm (goyal et al., 2003) 3.4 effect of contact time (determined with both dead and live biomass) to determine the effect of contact time 0.5 g of biomass (live and dead biomass were used separately) was added in a 100 ml solution of 1mg/l of cr (vi) in a 250 ml conical flask and incubated for 12, 24, and 48 hours respectively in a shaker incubator at 37° c and 150 rpm. after the incubation period samples were taken out, filtered, and analyzed using dpc assay at 540 nm (sethuraman and balasubramanian, 2010). the ph of the cr (vi) solution was adjusted to 6 when dead biomass was being used and ph was kept at 2 when optimization experiments were done with live biomass (as such was the optimum values, shown in the result section). this was followed for the rest of the experiments as well. guha et al. /journal of tropical forestry and environment vol. 11, no. 02 (2021) 24-36 27 3.5 effect of biomass loading (determined with both dead and live biomass) 0.5g, 1 g, and 2 g fungal biomass were added separately in 100 ml of 1 mg/l concentration of chromium solution and then incubated at 37° c for 24 hours at 150 rpm. after 24 hours, the samples were taken out, filtered, and analyzed using dpc assay at 540 nm (reya et al., 2012). 3.6 effect of temperature (determined with both dead and live biomass) the effect of temperature on biosorption efficiency was observed with a chromium (vi) concentration of 1 mg/l. 0.5g of biomass was added to 100 ml solution of 1 mg/l concentration of cr (vi) and incubated at various temperatures (20° c, 25° c, 30° c, 35° c, 40° c, and 45° c) for 24 hours at 150 rpm. after 24 hours samples were taken out, filtered, and analyzed using dpc assay at 540 nm (reya et al., 2012). 3.7 effect of initial metal ion concentration (determined with both dead and live biomass) 0.5 g of fungal biomass was added in 100 ml solution of different concentrations (1, 2, 3, 4, and 5 mg/l) of chromium (vi) in 250 ml conical flasks the flasks were then incubated in a shaker incubator at 37° c at 150 rpm for 24 hours. after 24 hours, the samples were taken out, filtered, and analyzed using dpc assay at 540 nm (reya et al., 2012). 3.8 effect of volume differences (keeping metal concentration constant) (determined with both dead and live biomass) 50, 100, 150, 200, and 250 ml solution of chromium (vi) of 1 mg/l concentration were prepared. to it, 0.5 g of biomass was added and incubated at 37° c with an agitation rate of 150 rpm for 24 hours. after 24 hours, the samples were taken out, filtered, and analyzed using dpc assay at 540 nm. 3.9 effect of varying combinations of biomass load and volume (for dead and live biomass) 1 mg/l concentration of chromium solutions was exposed to various combinations of biomass load and volume (0.5 g in 100 ml, 1 g in 200 ml, and 1.5 g in 300 ml). then the flasks were agitated in a shaker at 150 rpm and incubated at 37° c for 24 hours. after 24 hours, the samples were taken out, filtered, and analyzed using dpc assay at 540 nm. 4. biosorption efficiency calculation biosorption efficiency (%) was calculated using the following equation (bajpai and rai, 2010). e= (ci-cf)×100 ci where: e=percentage removal of hexavalent chromium ci=initial metal ion concentration (mg/l) cf=final metal ion concentration (mg/l) each experiment was repeated three times to get accurate results and the average was taken for the calculation of biosorption efficiency. 5. results 5.1 effect of pre-treatment (determined for dead biomass) metal adsorption to biomass can be manipulated by pre-treating the biomass with alkali, acid, and heat which may increase the amount of metal sorbed. the comparison for chromium adsorption capacities by a. nomius biomass when pre-treated with acids and alkalis shown in figure 1. it is seen that when the biomass was pre-treated with sulfuric acid, the adsorption efficiency was maximum (82%) whereas when pretreated with alkali (naoh) the adsorption efficiency was minimum (1%). (1) 28 adsorption of chromium may vary because of the action of chemical agents contributing to modifications in the cell wall structure. a similar observation was reported by reya et al., (2012) where they used a. oryzae and a. sojae biomass and the acid treatment yielded better results than alkali treatment. figure 01. trends in biosorption with varying pre-treatment agents 5.2 effect of pre-treatment agent (sulfuric acid) concentration (determined for dead biomass) the effect of various concentrations of sulphuric acid on biosorption by dead a. nomius biomass was studied and results are shown in figure 2. it was observed that the percentage removal of chromium increased with increase in the concentration of the pre-treatment agent and was maximum at 96.5% when 1n solution was used. figure 02. trends in biosorption with varying pre-treatment agent (h2so4) concentrations 5.3 effect of ph (determined with both dead and live biomass) the effect of ph on biosorption was studied and results are shown in figure 3. it was observed that the percentage removal of chromium was maximum at ph 6.0 and was found to be 98% (for dead biomass). as the ph increases from ph 2.0 to ph 6.0, there was an increase in the removal efficiency and after reaching ph 6.0 (optimum) it started to decline. (visoottiviseth and panviroj, 2001; jaglan et guha et al. /journal of tropical forestry and environment vol. 11, no. 02 (2021) 24-36 29 al., 2020). the cell wall of a. species contains a large number of surface functional groups. biomass has live sites capable of binding metal ions and such bond formation could be done by displacement of protons which can be determined by ph (marandi, 2011). positively charged metal ion uptake was increased because the charge of the fungal surface becomes negative under high ph values such as 6 (allaboun and abu al-rub, 2008). for live biomass, maximum biosorption efficiency was observed at ph 2 (93%) and then gradually decreased with increase in ph level. the percentage removal of chromium was maximum at ph 2.0 and was found to be 89% and 85% for a. oryzae and a. sojae respectively (reya et al., 2012). figure 03. trends in biosorption with varying ph 5.4 effect of contact time (determined with both dead and live biomass) the effect of contact time using dead a. nomius biomass was studied and results are shown in figure 4. for dead biomass, initially there was a gradual increase in the adsorption efficiency as contact time increased followed by a decrease in efficiency after 24 hours. the percentage removal was around 98% and 90% respectively for durations of 24 hours and 48 hours. as time passed, the metal uptake by the adsorbent surface slowed down, due to the competition for decreasing availability of live sites occupied by the metal ions remaining in the solution. santhi and guru reported synonymous results where they recorded maximum biosorption at 24 hours, using a. niger biomass as the biosorbent (santhi and guru, 2014).for live biomass, initially there was a gradual increase in the adsorption efficiency as contact time increased with the highest biosorption efficiency of 84% observed after 48 hours and further change was not observed, similarly to what has been reported by silah and gul (2017). 30 figure 04. trends in biosorption with varying treatment durations 5.5 effect of biosorbent dosage (determined with both dead and live biomass) the biosorbent dosage is also one of the significant factors to be considered for effective biosorption. it determines the sorbent/sorbate equilibrium of the system. chromium biosorption with varying biosorbent loads is shown in figure 05. from the figure it is observed that as the concentration of biosorbent increases from 0.5 g to 2 g there is increase in the percentage removal, which may be due to the increase in the number of binding sites on the biomass, with a maximum biosorption of 86% using 2 g live biomass. santhi and guru reported similar results where they used a. niger biomass as the biosorbent (santhi and guru, 2014).for the dead biomass, maximum biosorption efficiency was observed with 0.5 g. in many instances, lower biosorbent dosages yield higher uptake (vijayaraghavan et al., 2006). figure 05. trends in biosorption with varying amount of biomass guha et al. /journal of tropical forestry and environment vol. 11, no. 02 (2021) 24-36 31 5.6 effect of temperature (determined with both dead and live biomass) metal adsorption to biomass maybe manipulated by temperature variations. results are shown in figure 06. the percentage removal of chromium was maximum at 25° c (96%) and gradually decreased with increasing temperature, as for exothermic nature of the adsorption process, with a minimum at 45° c (mamaeri et al., 1999; el-gendy et al., 2017).temperature affects the cell wall stability components, configuration, and ionization of chemical moieties and energy-independent mechanisms are likely to be affected due to temperature changes since the process responsible for removal is largely dependent on the physiochemical characteristic of the medium (hassouna et al., 2018). santhi and guru (2014) reported similar results where they achieved maximum biosorption at 27° c, using a. niger biomass as the biosorbent. for live biomass, initially, there was a gradual increase in the adsorption efficiency with increasing temperature and the highest biosorption efficiency of 84% was recorded at 35° c. figure 06. trends in biosorption with varying temperature 5.7 effect of initial metal ion concentration (determined with both dead and live biomass) the effect of initial metal ion concentration on biosorption of cr (+6) is shown in figure 07. the percentage removal of chromium was around 95% to 72.8% with initial metal ion concentrations from 1 mg/l to 5 mg/l respectively. the percentage removal decreased as the concentration increased and this may be due to saturation of live sites (saleh et al., 2010). after attaining the optimum concentration, the efficiency decreased due to an increase in the metal dose which may be beyond the toxic threshold of the fungus. similar result was obtained by jaglan et al. (2020). santhi and guru (2014) also reported synonymous results with a. niger biomass where they also achieved maximum biosorption at 1 mg/l cr (vi) concentration which gradually decreased with increase in the metal concentrations tested. similarly, when live biomass was used there was a gradual decrease in the adsorption efficiency with increasing metal concentration. the highest efficiency was noted at chromium concentration of 1 mg/l. 32 figure 07. trends in biosorption with varying initial metal concentrations 5.8 effect of volume differences (keeping metal concentration constant) (determined with both dead and live biomass) metal adsorption to biomass maybe manipulated by variations in solution volumes. results are shown in figure 8. the percentage removal of chromium was maximum when 250 ml of solution volume was taken (95%) and gradually decreased with decreasing volumes. this may be due to the unavailability of space for optimal interactions with the biomass. similarly, for live biomass, the percentage removal of chromium was maximum when 250 ml of solution volume was taken (69%). figure 08. trends in biosorption with varying volumes keeping metal concentration constant guha et al. /journal of tropical forestry and environment vol. 11, no. 02 (2021) 24-36 33 5.9 effect of varying combinations of biomass load and volume (determined with both dead and live biomass) the combined effect of biomass loading and volume differences were studied for chromium removal and results are shown in figure 09. it was observed that the most effective combination was 0.5 g of biomass in 100 ml aqueous solution with an efficiency of 98%. for live biomass, the most effective combination was 1.5 g of biomass in 300 ml aqueous solution with an efficiency of 63%. figure 09. trends in biosorption with varying biomass and volume combinations 6. discussion the results show that the hexavalent chromium can be effectively removed up to 82% from an aqueous solution using sulfuric acid as the pre-treatment/inactivating agent using a. nomius biomass at 37° c. the results also showed that as the concentration of the sulfuric acid was increased, the percent removal was also found to increase linearly with a maximum of 96.5% at 1n. the effect of ph on biosorption efficiency was different between the dead and live biomass. for the dead biomass the ph optimum of the chromium solution was 6 while it was 2 for the live biomass. this may be, since treatment of the dead biomass with sulphuric acid might had already exposed or modified the cell wall structure which did not require any further modification for efficient biosorption and maximum efficiency was obtained near the neutral range. however, the live biomass which did not undergo any such treatment might have undergone some modification in its cell wall structure at acidic ph thereby showing optimum activity at ph 2. maximum chromium removal of 86% was obtained using 2 g live a. nomius biomass whereas 0.5 g of live biomass was enough to obtain the maximum efficiency. 96% chromium was removed at 25° c using dead biomass, but, it declined gradually at higher temperatures, whereas, maximum removal of about 84% was obtained when live biomass was used for biosorption and it took place at 35° c. maximum cr (vi) removal of about 95% was obtained when dead biomass was used and initially the concentration of cr (vi) was 1 mg/l and declined gradually at higher concentrations. for the live biomass also the maximum cr (vi) removal was obtained at 1 mg/l concentration. it was also found that 0.5 g biomass (dead) in 100 ml, 1 mg/l solution, was optimum for cr (vi) removal at ph 6.0 and 37° c. while for live biomass, maximum cr (vi) biosorption of 63% was obtained when 1.5 g of it was used in 300 ml at ph 2 and 1 mg/l of initial chromium concentration. the mechanism of cell surface sorption of heavy metal by dead biomass includes many processes like physical adsorption, ion exchange, chelation, electrostatic interactions, and metal ion complexation (sharma et al., 2016) whereas biosorption by live biomass is an active process whereby uptake of heavy 34 metals requires the metabolic activity of living organisms such as biomineralization, biotransformation, bioprecipitation, and bioaccumulation (khan et al., 2019). high environmental resistance, greater toxicity tolerance, no need for nutrition, maintenance, and storage of the biosorbents for long periods without any adverse effects are some definite bonus advantages of using dead biomass (javanbakht et al., 2014). metal uptake level of dead cell fungal has been observed to be greater than living cell, based on pretreatment methods that favorably exposes or modifies the functional groups on the cell surface (kapoor, 1998). 7. conclusion from the above observations it can be easily concluded, that dead biomass although is certainly superior to live biomass in biosorbing cr (vi) in many aspects as for the different parameters used but the live biomass is also moderately capable of removing hexavalent chromium from solutions. similar observations have been reported by dhankhar and hooda (2011), kapoor (1998). so, this study shows the application of biosorption using natural, abundant and cheap microbial biomass in the removal of metal ions from waste water and offers a high potential for large-scale exploitation. acknowledgment the authors wish to acknowledge their sincere thanks to the department of higher education science and technology and biotechnology, government of west bengal, for the financial support in this research work. references akpor, o. b. and muchiem m., 2010. remediation of heavy metals in drinking water and wastewater ztreatment systems: processes and applications. international journal of the physical sciences. 5:1807-1817. aksu, z., 2001. biochemical engineering journal, 7:79-84. allaboun, h. and abu al-rub, f.a., 2008. jordan journal of civil engineering, 2:124-138. ayangbenro, a. and babalola, o., 2017. a new strategy for heavy metal polluted environments: a review of microbial biosorbents. international journal of environmental research and public health, 14:94. ayele, a., haile, s., alemu, d. and kamaraj, m., 2021. comparative utilization of dead and live fungal biomass for the removal of heavy metal: a concise review. the scientific world journal, 2021. cai, c.x., xu, j., deng, n.f., dong, x.w., tang, h., liang, y., fan, x.w. and li, y.z., 2016. a novel approach of utilization of the fungal conidia biomass to remove heavy metals from the aqueous solution through immobilization. scientific reports, 6:1-12. dhankhar, r. and hooda, a., 2011. fungal biosorption an alternative to meet the challenges of heavy metal pollution in aqueous solutions. environmental technology, 32:467-491. el-gendy, m.m.a.a., ten, n.m., ibrahim, h.a.e.h. and abd el-baky, d.h., 2017. heavy metals biosorption from aqueous solution by endophytic drechslera hawaiiensis of morus alba l. derived from heavy metals habitats. mycobiology, 45:73-83. ferreira, g. l. da rocha, vendruscolo, f. and antoniosi filho, n. r., 2019. biosorption of hexavalent chromium by pleurotus ostreatus. heliyon. 5:01450. gadd, g. m., 2009. biosorption: critical review of scientific rationale, environmental importance and significance for pollution treatment. journal of chemical technology and biotechnology, 84:28. goyal, n., jain, s.c. and banerjee, u.c., 2003. comparative studies on the microbial adsorption of heavy metals. advances in environmental research, 7:311-319. guha, s., debnath, s. and gayen, s., 2020. isolation of hexavalent chromium (vi) tolerant fungi from tannery effluent and their growth responses to different concentrations of chromium (vi). sustainability, agri, food and environmental research. guha et al. /journal of tropical forestry and environment vol. 11, no. 02 (2021) 24-36 35 hassouna, m.e.m., marzouk, m.a., elbably, m.a. and el maghrabi, a.h., 2018. biosorption of iron by amended aspergillus versicolor from polluted water sources. biometrics and biostatistics international journal, 7:502-513. irawati, w., wijaya, y., christian, s. and djojo, e.s., 2016. characterization of heavy metals resistant yeast isolated from activated sludge in rungkut, surabaya, indonesia as biosorbent of mercury, copper, and lead. aip conference proceedings, 1744:20061. javanbakht, v., alavi, s.a. and zilouei, h., 2014. mechanisms of heavy metal removal using microorganisms as biosorbent. water science and technology, 69:1775-1787. jin, y., luan, y., ning, y. and wang, l,2018. effects and mechanisms of microbial remediation of heavy metals in soil: a critical review. applied sciences, 8:1336. joshi, n.c. 2018. biosorption: a green approach for heavy metals removal from water and waste waters. research journal of life sciences, bioinformatics, pharmaceutical and chemical sciences, 4:1-59. kapoor, a., 1998. removal of heavy metals from aqueous solution by fungi aspergillus niger. faculty of graduate studies and research, university of regina. khan, i.,aftab, m., shakir, s., ali, m., qayyum, s., rehman, m., haleem, k.s. and touseef, i., 2019. mycoremediation of heavymetal (cd and cr) polluted soil through indigenous metallotolerant fungal isolates. environmental monitoring and assessment, 191:585. lata, s., kaur, h. p. and mishra, t., 2019. cadmium bioremediation: a review. international journal of pharmaceutical sciences and research, 10:4120-4128. mameri, n., boudries, n., addour l., belhocine, d., lounici, h., grib, h. and pauss, a., 1999. zinc biosorption by a bacterial non-living streptomyces rimosus biomass. water resource. 33:13471354. marandi, r., 2011. biosorption of hexavalent chromium from aqueous solution by dead fungal biomass of phanerochaete crysosporium : batch and fixed bed studies. canadian journal on chemical engineering and technology, 2. philip, l., iyengar, l. and venkobachar, c., 1998. cr (vi) reduction by bacillus coagulans isolated from contaminated soils. journal of environmental engineering, 124:1165-1170. reya, i.i., rajamehala, m., lakshmi, p.m., and emilin, r.r., 2012. comparitive study on biosorption of hexavalent chromium using aspergillus oryzae ncim 637 and aspergillus sojae ncim 1198 from electroplating effluent. international journal of chemtech research, 4:1708-1719. al-garni, s.m., ghanem, k.m. and ibrahim, a.s., 2010. biosorption of mercury by capsulated and slime layerforming gram-ve bacilli from an aqueous solution. african journal of biotechnology, 9:6413-6421. santhi, r. and guru, v., 2014. biosorption of hexavalent chromium using aspergillus niger dead biomass and its optimization studies. international journal of current microbiology and applied sciences. 3(10):669-678. sethuraman, p., and balasubramanian, n., 2010. removal of cr(vi) from aqueous solution using bacillus subtilis, pseudomonas aeruginosa and enterobacter cloacae. international journal of engineering science and technology, 2:1811-1825. siddiquee, s., rovina, k., azad, s.a., naher, l., suryani, s. and chaikaew, p., 2015. heavy metal contaminants removal from wastewater using the potential filamentous fungi biomass: a review. journal of microbial and biochemical technology, 7:384-93. silah, h. and gül, ü.d., 2017, april. comparison of nickel biosorption properties of living and dead rhizopus arrhizus biosorbent. aip conference proceedings, 1833:020105 singh, a. and gauba, p., 2014. mycoremediation: a treatment for heavy metal pollution of soil. journal of civil and environmental engineering, 1:59-61. talukdar, d., sharma, r., jaglan, s., vats, r., kumar, r., mahnashi, m.h. and umar, a., 2020. identification and characterization of cadmium resistant fungus isolated from contaminated site and its potential for bioremediation. environmental technology and innovation, 17:100604. 36 sharma, s., rana, s., thakkar, a., baldi, a., murthy, r.s.r. and sharma, r.k., 2016. physical, chemical and phytoremediation technique for removal of heavy metals. journal of heavy metal toxicity and diseases, 1:1-15. usepa, 1992. sw-846 test method 7196a: chromium, hexavalent (colorimetric).https://www.epa.gov/sites/production/files/2015-12/documents/7196a.pdf/ vijayaraghavan, k., palanivelu, k. and velan, m., 2006. biosorption of copper (ii) and cobalt (ii) from aqueous solutions by crab shell particles. bioresource technology, 97:1411-1419. visoottiviseth, p. and panviroj, n., 2001. selection of fungi capable of removing toxic arsenic compounds from liquid medium. science asia, 27:83-92. yahaya, y.a. and don, m.m., 2014. pycnoporus sanguineus as potential biosorbent for heavy metal removal from aqueous solution: a review. journal of physical science, 25:1-32. https://www.epa.gov/sites/production/files/2015-12/documents/7196a.pdf/%20accessed%2013th%20june%202021 microsoft word mayuri bandara et al., /journal of tropical forestry and environment vol. 2, no. 02 (2012) 27-36 27 chlorpyrifos-induced histopathological alterations in duttaphrynus melanostictus (schneider 1799) tadpoles: evidence from empirical trials m. g. d. k. bandara 1 , m. r. wijesinghe* 1 , w. d. ratnasooriya 1 and a. a. h. priyani 2 1 department of zoology, faculty of science, university of colombo, colombo 03, sri lanka 2 department of pathology, faculty of medicine, university of colombo, colombo 03, sri lanka date received: 29-04-2012 date accepted: 21-06-2012 abstract this paper reports the histopathological responses of the gill, liver and tail muscle tissues in tadpoles of the asian common toad duttaphrynus melanostictus (schneider, 1799) exposed to chlorpyrifos a common organophosphorus pesticide. tadpoles of gosner stages 24-26 were continuously exposed to low, mid and high (500, 1000 and 1500 µgl –1 ) concentrations of chlorpyrifos for two weeks. histological alterations in the tissues of the surviving larvae were microscopically examined both at the end of the exposure period and after a week following the final exposure. several histological alterations were noted in the gills, liver and tail muscles of the larvae exposed to 1500 µgl –1 of chlorpyrifos. the gills of exposed larvae showed architectural distortion resulting from reduced primary and secondary gill lamellae and blood vessels, and alterations in the gill epithelium. in the liver sinusoidal congestion and dilation, cytoplasmic vacuolation and changes in hepatocytes such as hyperchromatic nuclei and nuclear fragmentation were observed. the tail muscle tissue suffered from severe atrophy and myotomal disintegration. although histological alterations in the gill and liver tissues were noted only at the high concentration, changes in the muscle tissue i.e. muscle degeneration and atrophy, were apparent at both low and mid concentrations. the degree of damage in surviving larvae in a week following the final exposure was lower than that observed during the exposure, probably indicating recovery or resistance. the findings of the present study emphasize the need to investigate possible sublethal damage induced by pesticides in amphibians inhabiting agricultural habitats. key words: chlorpyrifos, gills, histopathology, liver, muscles, tadpoles 1. introduction it is widely accepted that intensive use of pesticides has detrimental consequences on aquatic organisms found in agricultural landscapes. amphibians are known to be particularly susceptible to the adverse effects of pesticides (rouse et al., 1999). studies have shown that exposure to pesticide residues may result in direct mortality of amphibian larvae, whilst at the same time causing growth impairments, delays in development, and alterations in behavior and histopathological changes in tissues (bridges, 1997; kamrin, 1997; young et al., 2001; sumanadasa et al., 2008). histopathological responses of aquatic organisms have been used as an effective early warning tool in ecological risk assessment (adams et al., 1996; neskovic et al., 1996). although a considerable amount of information is available on mortality and growth relatively few studies have focused on histopathology of organisms exposed to environmental contaminants. *correspondence: mayuri@zoology.cmb.ac.lk tel: +94 71446277 issn 2235-9370 print / issn 2235-9362 online ©2012 university of sri jayewardenepura bandara et al., /journal of tropical forestry and environment vol. 2, no. 02 (2012) 27-36 28 studies on effects of pollutants on amphibians are particularly relevant to sri lanka, a global amphibian hotspot harboring 2 % of the world’s amphibians (pethiyagoda and manamendra-archchi, 2006). several species in the island have already become extinct and many species have experienced population declines and range reductions (iucn, 2007). the widespread application of pesticides and herbicides in the plantation sector has been implicated as a possible cause (pethiyagoda and manamendraarchchi, 2006). the organophosphorus pesticide, chlorpyrifos (o,o-diethyl o-3,5,6-trichloro-2-pyridyl phosphorothioate), is one of the most commonly used pesticides in sri lanka for the control of pests in rice, but is also used for other vegetable crops such as bean, pigeon pea, coconut and potato plantations. our broad aim was to investigate the potential toxicity of the commercially available product of chlorpyrifos on larvae of a selected amphibian species in sri lanka. in our first paper we provide evidence that chlorpyrifos induces significant elevations in mortality and causes retardations in growth and development in tadpoles of the asian common toad duttaphrynus melanostictus (wijesinghe et al. 2011). in this paper we examine the potential of chlorpyrifos to induce histologial alterations in vital tissues of larvae of the same species. the study species d. melanostictus is frequently found in association with human-altered habitats such as agricultural landscapes and urban settings in sri lanka. in general, breeding commences with the onset of the monsoons, but breeding may occur at any time of the year. the eggs are generally laid in running water, although they may breed in tanks, temporary or permanent ponds and pools (kirtisinghe, 1955). tadpoles of this species are easily reared under laboratory conditions. the occurrence of this species in many other south asian countries makes the results of the present study widely applicable. 2. methodology tadpoles of d. melanostictus corresponding to gosner stages 24-26 were simultaneously collected from three garden ponds in the colombo city where no pesticides were used. a commercial formulation of chlorpyrifos (pattas) was purchased from harcros company ltd, colombo. because there were no recorded field levels of chlorpyrifos in sri lanka, selection of pesticide concentrations for the exposure trials were based on laboratory investigations conducted elsewhere (bonfanti et al., 2004; gallo-delgado et al., 2006). accordingly, low, mid and high concentrations of chlorpyrifos (500, 1000 and 1500 µgl -1 ) were selected for the experiments. a stock solution was initially prepared and appropriate volumes were then added to glass tanks containing 2 l of tap water. each tank contained 18 larvae and both treatment and control (without pesticides) tanks were maintained in triplicate. the larvae were fed daily with commercially available fish food pellets (frf aquatic pet shop, colombo, sri lanka). experiments were carried out for three weeks (21 days) with two weeks of continuous exposure to chlorpyrifos and for a further one week after the final exposure. this period was selected because many small-scale farmers in a particular area apply pesticides to their paddy fields at different times over approximately two-to-three weeks. the streams near paddy fields would therefore receive pesticidecontaminated water via surface runoff repeatedly over this period. the half-life of chlorpyrifos in water at ph 7.0 and 35 o c is 12 days but increases to 35 days at 25 o c (miles et al., 1983). during the two weeks of exposure water was changed every three days and pesticide concentrations were renewed with each water change following sumanadasa et al., 2008, whilst only water was renewed in the week following the final exposure. at the end of the exposure period of two weeks and after one week following the final exposure surviving three tadpoles each from treatment and control tanks were randomly collected and fixed in zenker fixative overnight. larvae were dehydrated in a graded alcohol series and embedded in paraffin. longitudinal sections of 8µm thickness were prepared using a rotary microtome (yamato, tokyo, japan), and stained with haematoxylin and eosin. slides were examined under a light microscope (student microscope, nikon, tokyo, japan) and changes were noted. images were taken under the phase bandara et al., /journal of tropical forestry and environment vol. 2, no. 02 (2012) 27-36 29 contrast microscope (nikon –1001v, tokyo, japan). five random locations of each section obtained from one tadpole were examined and the damage to the tissue was ranked as no damage, minor damage and severe damage. epithelial thickness of the gill tissue was also measured using a graticule. 3. results the examination of tissue samples from gills, liver and tail muscles showed that chorpyrifos has the capacity to induce histopathological changes in all three tissues of d. melanostictus tadpoles at concentration of 500 µg l -1 and above. the histopathological changes in each of these tissues are as follows. 3.1 gill tissue the gill tissue of tadpoles in general consists of well-structured primary and secondary gill lamellae. this is evident in the gill tissues of the larvae not exposed to chlorpyrifos (control). however, as shown in figure 1, continuous exposure to the pesticide for two weeks caused architectural distortion of the gill tissue of the exposed larvae. the primary and secondary gill lamella in exposed larvae were much reduced or were completely absent in certain sections of the gill arch. where present the gill lamellae were less defined and smaller compared to that of the control larvae. the gills of the control larvae were also more compact and filled with prominent blood vessels, whereas in the gills of the treated larvae the blood vessels were noticeably reduced. greater vesicularisation was also apparent in larvae exposed to the pesticide in comparison to that of the control larvae. furthermore, thickening of the epithelial lining of the treated larvae was notable. the overall changes to the gills were assessed and ranked taking into consideration the magnitude of damage. all tadpoles exposed to 1500 µgl –1 for two weeks suffered severe damage. at 1000 µgl –1 nearly half of the larvae suffered from minor damage of the gill tissue while the remaining larvae showed no signs of damage. no damage was apparent in gill tissues of larvae exposed to the lowest concentrations. the thickness in the epithelium of the control larvae was 0.0019 mm whilst that of the larvae exposed to 1500 µg l -1 was 0.0046 mm (n=10 tadpoles per treatment or control). oedematous changes were also evident in exposed tadpoles after two weeks of exposure (figure 2). oedema in the gill lamellae also caused epithelial sloughing and detachment in larvae exposed to chlorpyrifos. (i) (ii) figure 1: histopathological responses of the gill tissues of (i) control larvae and (ii) d. melanostictus larvae exposed to 1500 µgl-1 of chlorpyrifos. note prominent gill lamella in control larvae and reduced gill lamella in treated larvae (magnification x100). bandara et al., /journal of tropical forestry and environment vol. 2, no. 02 (2012) 27-36 30 (i) (ii) figure 2: changes in the structure of the gill of d. melanostictus larvae (i) normal gill in control larvae and (ii) reduced gill tissue and oedema (o) in larvae exposed to 1500 µgl-1 of chlorpyrifos (magnification x 400). a notable observation with respect to gill damage was that, larvae exposed to the highest concentration continuously for two weeks exhibited greater distortion of gill architecture than the few surviving larvae, after one week of the final exposure. after a recovery period of one week, the primary and secondary gill lamellae were more numerous than at two weeks of continuous exposure. 3.2 liver tissue the liver tissue of the larvae not exposed to pesticides exhibited the typical paranchymatous appearance, whereas the liver tissue of the treated larvae suffered loss of cellular integrity (figure 3). the liver tissue of those exposed to chlorpyrifos showed sinusoidal congestion, which is the collection of an excessive amount of blood within the sinusoid (hibiya, 1982) resulting in the dialation of the sinusoids. the hepatocytes of treated larvae had marked cytoplasmic vacuolations and enlarged hyperchromatic nuclei and displayed nuclear fragmentation (figure 4). cellular oedema was also evident in the tissues of exposed tadpoles. (i) (ii) figure 3: liver tissues of (i) normal d. melanostictus tadpoles and (ii) tadpoles exposed to 1500 µgl-1 of chlorpyrifos. note the intercellular spaces in liver of exposed larvae (magnification x200). as with the gill, the overall damage of the live tissue was assessed and ranked. the liver tissue of all tadpoles exposed to 1500 µgl –1 for two weeks suffered severe damage while those exposed to both 500 and 1000 µgl –1 showed no signs of any damage and the liver tissue of these tadpoles were comparable in structure to those of the control. as with the gill, signs of recovery were noted in the liver tissues of the o bandara et al., /journal of tropical forestry and environment vol. 2, no. 02 (2012) 27-36 31 surviving larvae after three weeks, i.e. one week after the final exposure, with lower vacuolation and sinusoidal congestion and lesser number of hyperchromatic and fragmented nuclei as compared to that observed at the end of the two weeks of continuous exposure. (i) (ii) figure 4: histological alterations in the liver tissues of d. melanostictus larvae induced by chlorpyrifos exposure. (i) normal hepatocytes and (ii) hapatocytes in tissues of larvae exposed to 1500 ugl-1 of chlorpyrifos showing enlarged hyperchromatic and fragmented nuclei (magnification x1000). 3.3 tail muscle tissue it is apparent that exposure to chlorpyrifos caused excessive damage to the larval muscle tissues. in the unexposed larvae (control) lengthy myotomes were oriented in an orderly manner parallel to the notochord and were attached at regular intersomatic boundaries (figure 5). the muscles in the control larvae were compact with few spaces in between the myotomes. in contrast, the muscle tissues of the larvae exposed to chlorpyrifos, the myotomes showed fiber atrophy, where the number and volume of cells was greatly reduced. large myotomal spaces were also evident in the treated larvae. the degenerated muscle bundles were oriented in different directions, thus resulting in architectural distortion of the muscle tissues in the treated larvae. in contrast to both the gill and liver tissues, a progressive increase in disintegration and distortion of myotomes were noted from 500 to 1500 µgl –1 . considering damage to the muscle tissue, it was noted that all examined larvae showed severe damage at the highest concentration of 1500 µgl –1 whilst at 1000 µgl –1 only around 40 % showed severe damage whilst the reaming proportion showed minor damage. at 500 µgl –1 75 % showed minor whilst the balance 25 % showed no signs of damage. nevertheless, comparing the damage observed in the tail muscle tissue at two weeks of continuous exposure to chlorpyrifos with that a week later with no exposure, it was apparent that the damage in the latter instance was lower, a trend that was noted for both gill and liver tissues. 4. discussion histopathological changes are considered an essential biomarker, because they indicate the levels of exposure to environmental contaminants (rousseaux et al., 1995). the present study clearly demonstrates that the organophosphorous pesticide chlorpyrifos has the potential to induce histopathological changes in tissues of the larvae of the asian common toad duttaphrynus melanostictus. examination of the gill, liver and muscle tissues of the larvae exposed to 1500 µgl –1 of chlorpyrifos showed that these organs had undergone severe histological alterations while damage of a lower magnitude was noted at the mid and low concentrations. bandara et al., /journal of tropical forestry and environment vol. 2, no. 02 (2012) 27-36 32 (i) (ii) (iii) (iv) figure 5: effect of chlorpyrifos on tail muscle tissue of d. melanostictus larvae. (i), (iii) ts and ls of control larvae showing compact myotomes and (ii), (iv) ls and ts of treated larvae showing disintegrated myotomes (magnification x 400). previous studies investigating the effects of pesticides on gill tissues of aquatic organisms report that gills are highly susceptible to damage by such environmental pollutants (e.g. tommaso, 1986). gill morphology is therefore considered as a good indicator of the general health of aquatic animals (peters et al., 1984). in the present study, the gill tissue of larvae exposed to 1500 µgl –1 of chlorpyrifos had undergone extensive damage, with architectural distortion due to the reduction in the primary and secondary gill lamella, detachment and thickening of its epithelial lining and a marked reduction in the number and size of blood vessels. oedematous changes were also evident. similar structural changes in gills have been also shown in the fish clarias gariepinus when exposed to a glyphosate herbicide (olurin et al., 2006) and in tadpoles of scinax nasica as a result of paraquat exposure (lajmanovich et al., 1998). structural aberrations of the gill would no doubt cause serious changes in the respiratory potential of exposed organisms (kendall and dale, 1979). thickening of the epithelial lining increases the distance between water and blood across which oxygen is diffused, ultimately resulting in a reduction in oxygen uptake (nowak, 1992). a prominent reduction in blood vessels induced by pesticide exposure would restrict blood supply to the gills, also affecting the rate of gaseous exchange. the apparent oedematous changes, observed after two weeks of exposure to chlorpyrifos, in the present study, have been attributed to the increase in capillary permeability (roberts, 1978), which also affects the normal rate of respiration (skidmore and tovell, 1972). bufonid tadpoles are essentially obligate gill breathers and have rudimentary lungs throughout most of their larval development. in contrast to bufonids, other genera such as hyla and rana, have well-developed lungs from an early larval stage. therefore the tadpoles of the latter genera, unlike in the case of the bufonids, could compensate for the damage caused to gills (ultsch bandara et al., /journal of tropical forestry and environment vol. 2, no. 02 (2012) 27-36 33 et al., 1999). it is very likely that such alterations in the gill tissue induced by chlorpyrifos at 1500 µgl –1 may have caused respiratory stress and hence high levels of mortality observed in the tadpoles exposed to chlorpyrifos in the present (wijesinghe et al., 2011). the liver, because of its unique metabolic capability, is a prime target of most toxicants (hopwood et al. 2004). in the case of chlorpyrifos an investigation on rats has suggested that the liver is the main target organ of chlorpyrifos toxicity (zama et al., 2005). the detoxification process of chlorpyrifos and chlorpyrifos-oxon occurs predominantly in the liver and plasma of animals (atsdr, 1997; fao/who, 1999), most likely inducing histopathological changes in this organ. sinusoidal dilatation and congestion in the liver tissue observed in d. melanostictus larvae observed in the present study are very likely caused by the impairment of venous outflow of the hepatic veins (tanaka and wanless, 1998). according to olurin et al. (2006) when the liver is damaged excessive amounts of blood flows into the liver blocking the sinusoids. thus the blood flow from the hepatic artery and veins into the central vein, and the sinusoids are dialated in order to facilitate this blood flow. sakr et al. (2001) in a study where catfish clarias gariepinus were exposed to another organophosphorus insecticide hostathion has made similar observations. desai et al. (1984) and kent et al. (1988) have also observed cytoplasmic vacuolation and hyperchromatic nuclei in hepatocytes of the amphibian larvae that were exposed to high concentrations of chlorpyrifos. vacuolation generally results from degeneration of the cell membrane (olurin et al., 2006). in the case of the damage to hepatocytes, michael et al. (1988) state that hepatocytes with hyperchromatic nuclei could be taken as an indication of the exposure of the liver to toxicant-carcinogens. hepatocytes are the most abundant cell types within the liver and perform most of the liver’s essential functions such as the conversion of glucose to glycogen, regulation of lipids and deamination of amino acids (wright et al., 2004). structural damage of hepatocytes in response to xenobiotics such as pesticides can result in the impairment of liver function (hopwood et al., 2004). the tail muscle tissue of the tadpoles was also subject to histopathological alterations as a result of exposure to chlorpyrifos. muscle fiber atrophy i.e. the reduction in size and number of myotomes, was the most notable aberration in the present study. these observations comply with those of other studies conducted with organophosphorus insecticides. for instance xenopus laevis tadpoles exposed to chlorpyrifos and malathion showed complete distortion of myotomes (bonfantia et al., 2004). they further observed that myocytes were pointed in different directions with no clear cellular boundaries. hayes (1982) observed necrosis and the swelling and loss of striations of myofibers of rat skeletal muscles after administration of an organophosphate compound. ache inhibition is the primary mode of toxicity of organophosphorus pesticides and which in tail muscles typically cause repeated firing and hence continuous contraction of tail muscles fibres (lieu et al., 1997) and thus muscular damage. the atrophy of muscles is also caused by necrosis of muscle fibres, which in mammals is mediated by calcium mobilization (leonard and salpeter, 1979). the collapse of the trans-membrane protein complex between myotomes may also have contributed to the loss of connectivity between the myotomes (peng and chen, 1992). despite the severity of the histopathological damage caused to the gills, liver and tail muscle tissues of the exposed larvae at the end of two weeks of continuous exposure, it was interesting to note that the larvae surviving this exposure did not display extensive damage to the three tissues examined. this could be a result of either recovery from damage or as a result of being resistant to damage, both of which have been shown to occur in amphibians and other aquatic organisms. a study conducted by honrubia et al., (1993) reports that damage to the gill epithelium and gall-bladder of rana perezi exposed to a carbamate insecticide was reversed after a few days. sancho et al. (1997) noted that most of the metabolic disorders in the european eel (anguilla anguilla) exposed to the organophosphate pesticides fenitrothion, did not persist when allowed to recover in clean water for less than a week. in the present study too tadpoles were kept in clean water for a week after the final exposure. although potential for recovery has been demonstrated through empirical trials, it has been argued that non-target organisms bandara et al., /journal of tropical forestry and environment vol. 2, no. 02 (2012) 27-36 34 inhabiting aquatic systems associated with agricultural landscapes are often exposed to pesticides for several consecutive months (gruber and munn, 1998). in sri lanka since a given area typically contains many small paddies, with several local farmers using different application regimes, the shallow streams that drain the paddies repeatedly receive contaminated surface runoff. this being the case, recovery from damage would not be possible under field conditions. the lower degree of damage in tadpoles that have been kept in pesticide-free water for a week might also suggest some degree of resistance. the relative insensitivity of tadpoles to organophosphorus pesticides has been shown by snawder and chambers (1989) and is ascribed to either the resilience of ache (shapira et al. 1998) or the reduction in glutathione content and the increase in glutathione transferase activity (anguiano et al., 2001). 5. conclusion in conclusion the present study which shows that chlorpyrifos induces histopathological responses in important organs such as the gill, liver and muscles in amphibian larvae emphasizes the need to focus on non-lethal effects of continuous exposure of non-target organisms to pesticides. although the impact on mortality and development are typically used to ascertain the susceptibility of organisms to environmental pollutants, assessing sub-lethal effects such as histological alterations would also be essential to accurately estimate their potential risks on biotic communities. references adams, s. m., ham, k. d., greeley, m. s. lehew, r. f., hinton, d. e., and saylor, c. f. 1996. downstream gradients in bioindicator responses: point source contaminant effects on fish health. canadian journal of fisheries and aquatic sciences 53: 2177-2187. anguiano, o.l., de castro, a.c., and de d'angelo, a.m.p. 2001. the role of glutathione conjugation in the regulation of early toad embryos tolerance to pesticides. comparative biochemistry and physiology c 128: 35-43. atsdr. 1997. toxicological profile for chlorpyrifos. atlanta, agency for toxic substances and disease registry. bonfanti, p., colombo, a., orsi, f., nizzetto, i., andrioletti, m., bacchetta, r., mantecca, p., fascio, u., vailati, g., and vismara, c. 2004. comparative teratogenicity of chlorpyrifos and malathion on xenopus laevis development. aquatic toxicology 70: 189–200. bridges, c.m. 1997. tadpole swimming performance and activity affected by acute exposure to sub lethal levels of carbaryl. environmental toxicology and chemistry 16: 1935–1939. desai, a.k., joshi, u.m., and ambadka, p.m. 1984. histological observations on the liver of tilapia mossambica after exposure to monocrotophos, an organophosphorus insecticide. toxicology letters 21: 325-331. fao/who. (1999). pesticide residues in food. toxicological evaluations. international programme on chemical safety. food and agriculture organization and world health organization. gallo-delgado, s.m., palacio-baena, j.a., gutierrer-c, .p.d.a. 2006. effects of insecticide chlorpyrifos on growth rate and metamorphosis of smilisca phaeota (cope, 1862) (anura:hylidae). actualidades biologicas 28: 51-58. gruber, s.j., munn, m.d. 1998. organophosphate and carbamate insecticides in agricultural waters and cholinesterase (che) inhibition in common carp (cyprinus carpio). archives of environmental contamination and toxicology 35: 391-396. hayes, w.j.j. 1982. organic phosphorus pesticides. in: pesticides studied in man. baltimore, williams and wilkins. p.294. hibiya, t. 1982. an atlas of fish histology. normal and pathological features. kodansha ltd., tokyo. bandara et al., /journal of tropical forestry and environment vol. 2, no. 02 (2012) 27-36 35 honrubia, m.p., paz herráez, m., and alvarez, r. 1993. the carbamate insecticide zz-aphox ® induced structural changes of gills, liver, gall bladder, heart, and notochord of rana perezi tadpoles. archives of environmental contamination and toxicology 25: 184-191. hopwood, j., quigley, a., eagle, c., powell, h., eakins, j., and kenna, g.u.k, 2004. are primary rat hepatocyte cultures appropriate for predictive hepato toxicity testing of pharmaceuticals? toxicology 202, 33–127. iucn 2007. the 2007 red list of threatened fauna and flora of sri lanka. colombo, international union for conservation of nature, sri lanka. kamrin, m.a. 1997. pesticides profiles toxicity, environmental impact and fate. new york. kendall, m.w., dale, j.e. 1979. scanning and transmission electron microscope observations of rainbow trout gill. journal of fisheries research board canada. 36, 1072-1079. kent, m.l., myers, m.s., hinton, d.e., eaton, w.d., and elston, r.a. 1988. suspected toxicopathic hepatic necrosis and megalocytosis in pen-reared atlantic salmon salmo salar in puget sound, washington, usa. diseases of aquatic organisms 4: 91-100. kirtisinghe, p. 1955. the amphibian of ceylon .1 st edition. charles circus, colombo. lajmanovich, r.c., izaguirre, m.f., and casco, v.h. 1998. paraquat tolerance and alteration of internal gill structure of scinax nasica tadpoles (anura: hylidae). archives of environmental contamination and toxicology 34: 364-369. leonard, j.p. and salpeter, m.m. 1979. agonost-induced myopathy at the neuromuscular junction is mediated by calcium. journal of cell biology 82: 811-819. lien, n.t., adriaens, d., and janssen, c.r. 1997. morphological abnormalities in african cat fish (clarius gariepirus) larvae exposed to malathion. chemosphere. 35: 1475-1486. michael, l., kent, m.s., myers, d e., hinton, w.d., and eaton, r.a. 1988. suspected toxicopathic hepatic necrosis and megalocytosis in pen-reared atlantic salmon salmo salar in puget sound, washington, usa. diseases of aquatic organisms 4: 91-100. miles, j.r.w., harris, c.r., and tu, c.m. 1983. influence of temperature on the persistence of chlorpyrifos and chlorfenvinphos in sterile and natural mineral and organic soils journal of environmental science and health part b pesticides food contaminants and agricultural wastes 18: 705-712. neskovic, n.k., poleksic, v., elezovic, i., karan, v., and budimir, m. 1996. biochemical and histopathological effects of glyphosate on carp, cyprinus carpio l. bulletin of environmental contamination and toxicology 56: 295-302. nowak, b. 1992. histological changes in gills induced by residues of endosulfan. aquatic toxicology 23: 65-84. olurin, k.b., olojo, e.a.a.1., mbaka, g.o., and akindele, a.t.1. 2006. histopathological responses of the gill and liver tissues of clarias gariepinus fingerlings to the herbicide, glyphosate. african journal of biotechnology 5: 2480-2487. peters, g., hoffmann, r., and klinger, h. 1984. environmental induced gill disease of cultured rainbow trout (salmo gairdner). aquaculture 38: 105-126. pethiyagoda, r., and manamendra-archchi, k. 2006. sri lankan amphibians: diversity, uniqueness and conservation. in: c. n. b. bambaradeniya (ed). the fauna of sri lanka, world conservation union, colombo, sri lanka. peng, h.b., and chen, q. 1992. induction of dystrophin localization in cu;tured xenopus muscle cells by latex beads. journal of cell science 103: 551-563. roberts, r.j. 1978. fish pathology. baillierre tindall, london. rouse, j.d., bishop, c.a., and struger, j. 1999. nitrogen pollution: an assessment of its threat to amphibian survival. environmental health perspectives 107: 799-803. bandara et al., /journal of tropical forestry and environment vol. 2, no. 02 (2012) 27-36 36 rousseaux, c.g., branchaud, a., and spear, p.a. 1995. evaluation of liver histopathalogy in st. lawrence lake sturgeon (acipenser fulvescens) in comparison with a reference population. environmental toxicology and chemistry 14: 843-849. sakr s .a., hanafy, s.m., and el-desouky, n.e. 2001. histopathological, histochemical and physiological studies on the effect of the insecticide, hostathion on the liver of the catfish clarias gariepinus. egyptian journal aquatic biology and fisheries 6: 103-124. sancho, e., ferrando, m.d., and andreu, e. 1997. sublethal effects of an organophosphate insecticide on the european eel, anguilla anguilla. ecotoxicology and environmental safety 36: 57-65. shapira, m., seidman, s., livni, n., and soreq, h. 1998. in vivo and in vitro resistance to multiple anticholinesterase in xenopus laevis tadpoles. toxicology letters 28: 205-209. skidmore, j.f., and tovell, p.w.a. 1972. toxic effects of zinc sulphate on the gills of rainbow trout. water research 6: 217-30. snawder, j.e., and chambers, j.e. 1989. toxic and developmental effects of organophosphorus insecticides in embryos of the south african clawed frog. journal of environmental science and health 24: 205-218. sumanadasa, d.m., wijesinghe, m.r., and ratnasooriya, w.d. 2008. effects of diazinon on larvae of the asian common toad (bufo melanostictus schneider 1799). environmental toxicology and chemistry 27: 157-162. tanaka, m., and wanless, i.r. 1998. pathology of the liver in budd-chiari syndrome: portal vein thrombosis and the histogenesis of veno-centric cirrhosis, veno-portal cirrhosis, and large regenerative nodules. herpetology 27: 488-496. tommaso, t.r. 1986. comparative toxicity of nitrate in fresh water fish. aquatic toxicology 8: 129-137. ultsch, g.r., bradford, d.f., and freda, j. 1999. physiology: coping with the environment. university of chicago press, chicago. wijesinghe, m. r., bandara, m.g.d.k., ratnasooriya, w. d. and lakraj, g. p. 2011. chlorpyrifosinduced toxicity in duttaphrynus melanostictus schneider 1799 larvae. archives of environmental contamination and toxicology, 60: 690-696. wright, m.c., mann, d.a., orr1, j.g., hawksworth1, g.m., marek1, c.j., leel, v., haughton, e.l., koruth, m., murray, g.i., trim, j.e., and elrick, l.j. 2004. intercellular signaling by cytokines and the fibrogenic response of the liver to chronic liver damage. toxicology 202: 33–127. young, b.e., lips, k.r., reaser, j.k., ibanez, r., salas, a.w., cedeno, j.r., coloma, l.a., ron, s., marca, e.la., meyer, j r., munoz, a., bolanos, f., chaves, g., and romo, d. 2001. population declines and priorities for amphibian conservation in latin america. conservation biology 15: 12131223. zama, d., meraihi, z., boubekri, n., amrani, a., tebibel, s., and baali, n. 2005. assessment of the changes in some diagnostic enzymes and other parameters in wistar albino rats treated with pesticides during gestation. .algeria sciences and technologies 23: 51-56. 36 pre-sowing treatments accelerate germination percent for restoration of fourteen threatened tree species in bangladesh g.n.t. hasnat*, m.a. hossain and m.k. hossain institute of forestry and environmental sciences, university of chittagong, chittagong-4331, bangladesh date received: 11-05-2018 date accepted: 23-12-2019 abstract ecologically valuable native tree species are becoming threatened due to deforestation, forest fragmentation and preference of fast-growing exotics than the native ones in plantation. one of the main reasons for the preference of exotic species than the native ones is its higher rate of germination and rapid growth. the effect of different pre-sowing treatments was studied on fourteen threatened tree species of bangladesh to find out the appropriate treatments for speed up germination rate and initial seedling growth. these species are ecologically valuable multipurpose indigenous trees of bangladesh. methanol extract of castanopsis indica leaves could decrease the tumor ehrlich ascites carcinoma volume and weight. lophopetalum wightianum is a globally threatened tree species. hard coated seeds of canarium resiniferum, castanopsis indica, protium serratum, quercus acuminata and vitex peduncularis were treated with sand paper, nicking, normal water, hot water, h2so4 and hcl. soft coated seeds of brownlowia elata, dichopsis polyantha, firmiana colorata, lophopetalum wightianum, pterospermum acerifolium, pterospermum semisagittatum, pterygota alata, schleichera oleosa and sterculia villosa were sown in polybags, propagator house and nursery bed in normal, flat and 45o angle positions. among all hard-coated seeds, castanopsis indica showed significantly higher germination percentage (67%) after seeds treated with sandpaper in comparison to control (25%). soft-coated seeds of lophopetalum wightianum showed significantly higher germination percentage (90%) among all studied species when sown in propagator house, whereas in natural condition it provides only 26% germination rate. this paper will help to restore ecologically valuable threatened species. keywords: pre-sowing treatment, globally and nationally threatened tree species, germination rate, hard or soft-coated seed, bangladesh 1. introduction bangladesh had a rich floral diversity containing about 5,700 species of angiosperms (khan, 1977; hossain, 2001). however, the floral diversity has been disrupted (haque et al., 1997; uddin and misbahuzzaman, 2007; hossain et al., 2012) and the natural forests have been degraded along with its native tree species (hossain, 2001; hossain et al., 2012). native tree species are becoming threatened due to forest disturbance and hazardous invasion of fast-growing exotics (islam, 2003; afrin, 2010; mangla et al., 2011). a total of 486 plant species in bangladesh are considered as threatened of which 449 are angiosperms (irfanullah, 2011). among these, some valuable timber species are also included, which are ecologically and economically important (khan et al. 2001; hossain et al. 2004). one of the ecologically valuable timber species is castanopsis indica (roxb.), commonly known as shil batna, which has medicinal value too. methanol extract of castanopsis indica (meci) leaves has a significant effect on ehrlich ascites carcinoma (eac) cell. a dose of dependent manner can decrease the tumor volume and tumor weight, and elevate the life span of eac tumor bearer (dolai et al., 2012). ____________________________ *correspondence: gnthasnat@yahoo.com issn 2235-9370 print/issn 2235-9362 online © university of sri jayewardenepura doi: https://doi.org/10.31357/jtfe.v9i2.4466 hasnat et al. /journal of tropical forestry and environment vol. 9, no. 02 (2019) 36-45 37 another important native tree of bangladesh is lophopetalum wightianum (arn.), locally known as raktan, a globally threatened tree species (iucn, 1998). natural regeneration of exotic species through seed dispersal is too high than native tree species (flores-moreno, 2013). the germination rate of major plantation exotic species is also greater than native species (klink, 1996; wainwright and cleland, 2013). in natural forests as well as in plantation, natural regeneration of some native species is very low (hossain, 2003; uddin et al., 2013) because of poor germination percentage in comparison to fastgrowing species (pallewatta et al., 2003; afrin, 2010). nursery pre-sowing treatment is the primary and only step to recover these ecologically valuable threatened native trees by increasing their germination rate to compete with economically valuable exotics (hossain and pasha, 2001; myers and bazely, 2003). appropriate pre-sowing treatment could only speed up germination rate and thus assure more germination of seeds sown. the present investigation was designed to find out the appropriate pre-sowing treatments for maximum germination percent of the species, particularly fourteen native threatened tree species of natural forests of bangladesh. this paper will be a paradigm for future studies on pre-sowing treatment effects of other valuable tree species to restore on the earth from becoming extinct. 2. methodology 2.1 study site, seed collection areas, times and pre-sowing treatments the experiment was carried out during 2012-13 in the seed research laboratory, propagator house1 and the nursery of the institute of forestry and environmental sciences, chittagong university (ifescu), bangladesh. the species along with their seed collection time, seed collection area and pre-sowing treatments are shown in table 1. 2.2 germination percentage/ germination rate germination was observed and recorded at every day after seeds sown and continued up to six months to find out the last germination of the seeds. germination percentage was calculated by counting the number of seeds germinated out of 100 from beginning to end of the experiment (dwivedi, 1993; kumar, 1999). germination percentage = number of seeds germinated number of seeds sown ×100 3. results and discussion the highest germination percentage (100%) was found in p. semisagittatum when seeds were sown in commonly used polybags in flat position. except p. serratum, highest germination was found only after providing pre-sowing treatments in the remaining 13 species. in b. elata, 96% germination was found when seeds sown in normal polybags without any pre-sowing treatment (control) and highest germination percentage (98%) observed when sown in propagator house (figure 1). c. resiniferum provided 20% germination rate when seeds sown without any pre-sowing treatment in normal polybags (control). but highest germination (33%) was found in normal water treatment for 24 hours and h 2so4 treatment (10%) for 3 minutes (table 2). c. indica attained only 25% germination when seeds sown in polybags without any pre-sowing treatment (control), but highest germination (67%) was observed when seeds were treated with sandpapers rubbing at the distal end and sown in polybags (figure 1). d. polyantha showed 29% germination rate when seeds sown in normal polybags without any pre-sowing treatment (control), but germination increased up to 47% when sown in propagator house (table 2). 1 propagator house: greenhouse is a structure, primarily of glass, in which temperature and humidity can be controlled for the cultivation or protection of plants. propagator house is one type of greenhouse with a bed consists of sylhet sand with controlled temperature and humidity. (1) 38 table 1: seed collection areas, collection time and pre-sowing treatments provided to the species. scientific name local name hard/ soft coated seeds collected from fruit/seed collection (month) pre-sowing treatments brownlowia elata moos soft ukhiya august controli, seeds sown in propagator house, nursery bed, polybags with soil only canarium resiniferum dhup hard adampur, moulavi bazar october control, whole fruits sown in polybags, propagator house, seeds treated with sandpaper, nicking, normal water (24 hours), hot water (1 minute), h2so4 (3 and 5 minutes), hcl (3 and 5 minutes), seeds sown in propagator house castanopsis indica shil batna hard dulhazara august control, seeds treated with sandpaper, nicking, normal water (24, 48, 72 hours), hot water (1 minute), h2so4 (5 minutes), hcl (5 minutes), seeds sown in propagator house dichopsis polyantha tali soft hazarikhil march control, seeds sown in propagator house firmiana colorata udal soft ampu para, bandarban april control, seeds sown in propagator house lophopetalum wightianum raktan soft lawachara august control, seeds sown in propagator house and nursery bed protium serratum gutgutia hard kaptai september control, seeds treated with sandpaper, nicking, normal water (24 hours), hot water (1 minute), h2so4 (1 and 3 minutes), hcl (1 and 3 minutes), fruits sown in propagator house pterospermum acerifolium moochku nda soft kaptai april control, seeds sown in shade, flat position pterospermum semisagittatum lana asaar soft chunati, satkania april control, seeds sown in shade, flat position pterygota alata narikeli soft rangpur january control, seeds sown with more than 45o angles, under shade with straw, under shade with chatai, in propagator house quercus acuminata kali batna hard dulhazara august control, seeds treated with sandpaper, nicking, normal water (24, 48, 72 hours), hot water (1 minute), h2so4 (5 minutes), hcl (5 minutes), seeds sown in propagator house schleichera oleosa kusum soft madhupur sal forest, tangail september control, seeds treated with sandpaper, nicking, normal water (24 hours), seeds sown in propagator house sterculia villosa udal soft jibannagar, bandarban april control, seeds sown in propagator house vitex peduncularis horina goda hard dulhazara august control, seeds sown in propagator house, nursery bed hasnat et al. /journal of tropical forestry and environment vol. 9, no. 02 (2019) 36-45 39 table 2: germination percentage of fourteen native threatened tree species after providing pre-sowing treatments in comparison to without any treatment (control). scientific name local name family germination (%) (*control) highest germination (%) pre-sowing treatment(s) for highest germination (%) fruits/seeds sown in b. elata moos apocynaceae 96 98 seeds sown in propagator house propagator house c. resiniferum dhup burseraceae 20 33 normal water (24 hours), 10% h2so4 (3 minutes) polybag c. indica shil batna fagaceae 25 67 seeds treated with sandpaper polybag d. polyantha tali sapotaceae 29 47 seeds sown in propagator house propagator house f. colorata udal sterculiaceae 83 95 seeds sown in propagator house propagator house l.wightianum raktan celastraceae 26 90 seeds sown in propagator house propagator house p. serratum gutgutia burseraceae 30 30 control polybag p. acerifolium moochkunda sterculiaceae 63 77 seeds sown flat position polybag p. semisagittatum lana asaar sterculiaceae 87 100 seeds sown flat position polybag p. alata narikeli sterculiaceae 74 86 seeds sown in propagator house propagator house q. acuminata kali batna fagaceae 77 88 seeds treated with sandpaper polybag s. oleosa kusum sapindaceae 25 42 seeds treated with sandpaper, normal water (24 hours) polybag s. villosa udal sterculiaceae 76 80 seeds sown in propagator house propagator house v. peduncularis horina goda verbenaceae 38 46 seeds sown in propagator house propagator house *control: seeds sown in normal position in commonly used polybags (4”x6”) only with a sowing media of soil and cowdung (3:1) in sun lights and without any pre-sowing treatment. f. colorata seeds provide 83% germination in commonly used polybags without any pre-sowing treatment (control), but highest germination (95%) was observed in propagator house (table 2). in l. wightianum, only 26% germination was found in seeds without any pre-sowing treatment and sown in normal polybags (control) but it increased to 90% in propagator house. highest germination of p. serratum was 30% and it was found in control (figure 1). germination percentage of p. acerifolium and p. semisagittatum were 63% and 87% respectively in control while highest (77% and 100% respectively) were found when seeds sown in flat position in polybags (figure 1). in case of p. alata, 74% seeds were germinated when sown in polybags without any treatment, and highest germination (86%) was found in propagator house. q. acuminata exhibits 77% germination in control and highest rate (88%) was observed when seeds rubbed with sandpaper at the distal end and sown in polybags (table 2). 40 figure 1. germination percentage in control and highest germination percentage after pre-sowing treatment. highest germination percentage (42%) of s. oleosa was found in seeds sown in polybags after treated with sandpaper rubbing at the distal end and normal water immersion treatment for 24 hours. however, without any pretreatment, it was only 25% (figure 1). in s. villosa maximum germination (80%) was found when seeds sown in propagator house, but in control it was 76% only. v. peduncularis seeds germinated 38% without any pre-sowing treatment (control) and highest germination rate was 46% found in seeds sown in propagator house (table 2). the findings of the study showed that, seeds sown in propagator house in sand bed offered highest germination percentage 98%, 47%, 95%, 90%, 86%, 80% and 46% respectively in soft-coated seeds of six species namely, b. elata (figure 2), d. polyantha (figure 5), f. colorata (figure 6), l. wightianum (figure 7), p. alata (figure 11), s. villosa (figure 14) and hard-coated seeds of v. peduncularis (figure 15). seeds with hard coat treated with normal water for 24 hours and 10% concentrated h2so4 for 3 minutes provided highest germination percentage (33%) in c. resiniferum (figure 3) that supports the findings of bebawi and mohamed (1985); hasnat et al. (2017); laurent and chamshama (1987) and some et al. (1989). hard coated seeds of c. indica (figure 4) and q. acuminata (figure 12) showed maximum germination (67% and 88% respectively) with sand paper treatment which supports the reports of schmidt (2000). soft-coated seeds of s. oleosa (figure 13) also provided maximum germination (42%) both in sandpaper treatment and normal water treatment for 24 hours (hasnat et al., 2014). in p. acerifolium (figure 9) and p. semisagittatum (figure 10), maximum germination (77% and 100% respectively) was observed when the seeds sown flat position in normal polybags. these results support that different pre-sowing treatments enhance germination rate of different species (bewley and black, 1982; doran et al., 1983; kumar, 1999; napier, 1987; palani et al., 1995; schmidt, 2000). only in p. serratum (figure 8) the highest germination (30%) was found in control. hasnat et al. /journal of tropical forestry and environment vol. 9, no. 02 (2019) 36-45 41 figure 2. 60 days old seedling of moos (brownlowia elata) in poly-bag. figure 3. 90 days old seedling of dhup (canarium resiniferum). figure 4. 90 days old seedling of sil batna (castanopsis indica). figure 5. 90 days old seedling of tali (dichopsis polyantha). figure 6. 30 days old seedling of udal (firmiana colorata). figure 7. 45 days old seedling of raktan (lophopetalum wightianum). 42 figure 8. 15 days old seedling of gutgutya (protium serratum). figure 9. 90 days old seedlings of mochkunda (pterospermum acerifolium). figure 10. 90 days old seedling of lana assar (pterospermum semisagittatum). figure 11. 30 days old seedling of buddho narikel (pterygota alata). figure 12. 40 days old seedling of kali batna (quercus acumunata). figure 13. 150 days old seedlings of kusum (schleichera oleosa) [germinated in polybag (left) and transplanted from propagator house (right)]. hasnat et al. /journal of tropical forestry and environment vol. 9, no. 02 (2019) 36-45 43 figure 14. 30 days old seedling of udal (sterculia villosa). figure 15. 50 days old seedling of horina (vitex peduncularis). 44 references afrin, s., sharmin, s. and mowla, q.a., 2010. the environmental impact of alien invasive plant species in bangladesh. proceedings of international conference on environmental aspects of bangladesh (iceab10), japan, 62-64. bebawi, f.f. and mohamed, s.m., 1985. the pretreatment of seeds of six sudanese acacias to improve their germination response. seed science and technology, 13:111-119. bewley, j.d. and black, m., 1982. physiology and biochemistry of seeds in relation to germination, viability, dormancy and environmental control. springer-verlag, berlin, 1-375. dolai, n., karmakar, i., kumar, r.b., bala, a., mazumder, u.k. and haldar, p.k., 2012. antitumor potential of castanopsis indica (roxb. ex lindl.) a. dc. leaf extract against ehrlich's ascites carcinoma cell. indian journal of experimental biology, 50:359-365. doran, j.c., turnbull, j.w., boland, d.j. and gunn, b.v., 1983. handbook on seeds of dry-zone acacias. a guide for collecting, extracting, cleaning, and storing the seed and for treatment to promote germination of dry-zone acacias, division of forest research, csiro, po box 4008, canberra a c t 2600, australia. 1-92. dwivedi, a.p., 1993. a text book of silviculture. international book distributors. 9/3 rajpurroad, dehradun-248001, india.1-505. flores-moreno, h., thomson, f.j., warton, d.i. and moles, a.t., 2013. are introduced species better dispersers than native species? a global comparative study of seed dispersal distance. plos one, 8, e68541. haque, a., nandy, p. and ahmed, f.u., 1997. forest genetic resources conservation and utilization in bangladesh. in plant genetic resourcesbangladesh perspective (ed) hossain, m.g., arora, r.k. and mathur, p.n. proc. of a national workshop on plant genetic resources held on 26-29 august at barc, dhaka.104-132. hasnat, g.n.t., hossain, m.k., bhuiyan, m.k. and alam, m.s., 2014. effect of pre-sowing treatments on germination and initial growth of seedlings of kusum (schleichera oleosa). international journal of usufructs management, 15:3-9. hasnat, g.n.t., hossain, m.k., alam, m.s. and hossain, m.a., 2017. effect of pre-sowing treatments on seed germination and seedling growth of canarium resiniferum, a rare native tree of bangladesh. journal of forest and environmental science, 33:226-232. hossain, m.k., 2001. a review of forest biodiversity conservation in bangladesh. journal of forestry and environment, 1:102-110. hossain, m.k., 2003. exotic invasive plants in south-eastern hill forests of bangladesh. 7th international conference on the ecology and management of alien plant invasions, november 3-11, 2003 at wyndham bonaventure resort, fort lauderdale and miami university, florida, usa. hossain, m.k. and pasha, m.k., 2001. alien invasive plants in bangladesh and their impacts on the ecosystem. in: assessment and management of alien species that threaten ecosystems, habitats and species. abstracts of keynote addresses and posters presented at the sixth meeting of the subsidiary body on scientific, technical and technological advice, held in montreal, canada, from 12-16 march. montreal, secretariat of the convention on biological diversity (scbd).73-75 hossain, m.k., rahman m.l., hoque, a.t.m.r. and alam, m.k., 2004. comparative regeneration status in a natural forest and enrichment plantations of chittagong (south) forest division, bangladesh. journal forestry research, 15:255-260. hossain, m.d., hossain, m.a. and hossain, m.k., 2012. composition and diversity of tree species in dud-pukuria natural forests of chittagong (south) forest division, bangladesh. bangladesh journal of forest science, 32:10-19. https://www.ncbi.nlm.nih.gov/pubmed/?term=dolai%20n%5bauthor%5d&cauthor=true&cauthor_uid=22803326 https://www.ncbi.nlm.nih.gov/pubmed/?term=karmakar%20i%5bauthor%5d&cauthor=true&cauthor_uid=22803326 https://www.ncbi.nlm.nih.gov/pubmed/?term=kumar%20rb%5bauthor%5d&cauthor=true&cauthor_uid=22803326 https://www.ncbi.nlm.nih.gov/pubmed/?term=bala%20a%5bauthor%5d&cauthor=true&cauthor_uid=22803326 https://www.ncbi.nlm.nih.gov/pubmed/?term=mazumder%20uk%5bauthor%5d&cauthor=true&cauthor_uid=22803326 https://www.ncbi.nlm.nih.gov/pubmed/?term=haldar%20pk%5bauthor%5d&cauthor=true&cauthor_uid=22803326 https://www.ncbi.nlm.nih.gov/pubmed/22803326 hasnat et al. /journal of tropical forestry and environment vol. 9, no. 02 (2019) 36-45 45 irfanullah, h.m., 2011. conserving threatened plants of bangladesh: miles to go before we start? bangladesh journal of plant taxonomy, 18:1-91. islam, s.s., 2003. state of forest genetic resources conservation and management in bangladesh. forest genetic resources working papers. working paper fgr/68e. forest resources development service, forest resources division, forestry department. food and agriculture organization of the united nations (fao), rome, italy. 1-31 khan, m.s., 1977. flora of bangladesh. report 4. commelinaceae. bangladesh national herbarium, bangladesh agriculture research council (barc), farmgate, dhaka. khan, m.s., rahman, m.m. and ali, m.a. (ed) 2001. red data book of vascular plants of bangladesh. bangladesh national herbarium. binimoy printers, 37/2 purana paltan, dhaka-1000. klink, c.a., 1996. germination and seedling establishment of two native and one invading african grass species in the brazilian cerrado. journal of tropical ecology, 12:139-147. kumar, v., 1999. nursery and plantation practices in forestry. scientific publishers, 5a, new pali road, po box 91, jodhpur-342001.1-531. laurent, n., chamshama, s. a. o., 1987. studies on the germination of erythrina abyssinica and juniperus procera. the international tree crops journal, 4:291-298. mangla, s., sheley, r.l., james, j.j. and radosevich, s.r., 2011. intra and interspecific competition among invasive and native species during early stages of plant growth. plant ecology, 212:531542. myers, j.h., bazely, d., 2003. ecology and control of introduced plants. published by the press syndicate of the university of cambridge the pitt building, trumpington street, cambridge, united kingdom.1-313. napier, i., 1987. pre-germination treatment of cassia siamea and leucaena leucocephala seeds. banko janakari, 1:5-6. palani, m., dasrhagir, m.g. and kumaran, k., 1995. effect of pre-sowing chemical treatment on germination and seedling growth in acacia nilotica. international tree crops journal, 8:189192. pallewatta, n., reaser, j.k. and gutierrez a.t., 2003. invasive alien species in south-southeast asia: national reports and directory of resources. global invasive species programme, cape town, south africa. 1-111. schmidt, l., 2000. guide to handling tropical and subtropical forest seed. danida forest seed center, krogerupvej 21, dk-3050 humleback, denmark. 1-510. some, l.m., gamene, c.s. and verwey, h., 1989. a study of the causes of poor germination of anogeissus leiocarpus seeds. in: tropical tree seed research (ed) turnbull, j.w. proceedings of an international workshop held at the forestry training centre, gympie, qld, australia, 21-24 august, aciar, 28:37-40. uddin, s.m.m. and misbahuzzaman, k., 2007. tree species diversity in dulhazara safari park of bangladesh. malaysia applied biology, 36:33-40. uddin, m.b., steinbauer, m.j., jentsch, a., mukul, s.a. and beierkuhnlein, c., 2013. do environmental attributes, disturbances and protection regimes determine the distribution of exotic plant species in bangladesh forest ecosystem? forest ecology and management, 303:72-80. wainwright, c.e.and cleland, e.e., 2013. exotic species display greater germination plasticity and higher germination rates than native species across multiple cues. biological invasion 15:22532264. iucn, 1998. lophopetalum wightianum. world conservation monitoring centre. the iucn red list of threatened species. 46 _____________________________________________ *correspondence: muktipadapanda@gmail.com issn 2235-9370 print/issn 2235-9362 online © university of sri jayewardenepura 78 insect flower visitors and their role in mangrove pollination: a study from east coast of india m. panda1,3*, n. lele2, r.n. samal3, d. dalai4, s.p. parida5 and t.v.r. murthy2 1department of botany, banki (autonomous) college, odisha, india 2space application center (sac-isro), ahmadabad, india 3chilika development authority, department. of forest and environment, odisha, india 4research scholar, national rice research institute, odisha, india 5centurian university of technology and management, odisha, india date received: 23-02-2019 date accepted: 16-12-2019 abstract insects play a critical role in bringing successful pollination in angiosperms. mangrove pollination is a poorly studied aspect from scientific community. this particular work investigated the insect visitors and other prospective of mangrove flowers. twenty two species (i.e., 17 true and 5 mangrove associates) from bhitarkanika wildlife sanctuary and devi estuary of odisha state (east coast of india) were selected; plants were pre-marked and visiting insects were recorded starting from 07.00 am to 13.00 pm during the flowering period of each species. fifty three species of insects which belongs to seven orders, twenty five families and forty four genera were recorded. the highest, i.e., 14 sp. of insects had been recorded from aegiceras corniculatum which is a small tree and riverine mangrove. among insects, bees were found as the most common flower visitors (in 82% mangroves) and particularly “honey bee”, i.e., apis dorsata visited to sixteen mangrove species (i.e., 73% mangroves). bees, particularly honeybee (a. dorsata), sweet bee (lasioglossum sp.) and carpenter bee (xylocopa pubescens) were actively engaged in pollen dispersal. resident time and visitation rate supported that bees with highest visitation rate and low resident time were powerful candidates in bringing mangrove pollination. wasps, beetles and butterflies act more to be foraging species. facilitation of bee management and particularly supporting apiculture will help to increase pollination successes of rare and threatened mangroves at regional and global level. keywords: mangrove, flower, pollination, bees, forest conservation 1. introduction mangrove ecosystems are well known in terms of productivity, role of coastal protectio n, a habitat for diverse flora and fauna and most importantly as a large carbon pool both in living tissues and in the form of sediments. mangal loss is over alarming and thus had been legalised in many countries. long term conservation only possible through maintaining a stable population structure and flora diversity in the ecosystem. this depends on successive reproduction and subsequent regeneration of mangrove species. pollinators are one such group whose effective management can maximise reproductive success of rare and endemic mangroves. pollinators depend less on the plants than the plants on them (tomlinson, 2016). pollination benefits society by increasing food security, improving livelihoods and act as a key driver in the maintenance of biodiversity and ecosystem function (pratap, 2011). generally, pollination is done almost completely by canopy dwellers such as bats, birds, moths, butterflies, bees and other insects (alongi, 2009). identification of effective pollinator in forest with large doi: https://doi.org/10.31357/jtfe.v9i2.4470 mailto:muktipadapanda@gmail.com panda et al. /journal of tropical forestry and environment vol. 9, no. 02 (2019), 78-92 79 canopy like mangrove is difficult. tomlinson (2016) described pollination in terms of flower visitors that is presumed pollinators. wild pollinators (mostly bees and flies) can be quite important for plants requiring insect pollination (capinera, 2010). not all bees gather nectar and produce honey but all of them gather and store up pollen grains and do cross pollination in flowering plants (mani, 1995). the plants at most risk of loss which are dioecious and self-incompatible, and those that propagate only by seeds (kearns and inouye, 1997). the floral and pollination biology of mangrove plants has been moderately studied (raju, 1990, raju et al., 1994, mitra et al., 2013). mangroves have both self-pollinating and cross-pollinating mechanisms that vary with species (kathiresan and bingham, 2001, tomlinson, 2016). these pollinators are a group of animals which includes birds, bats and insects like butterflies, bees, beetles, flies and wasps etc. (azuma et al., 2002; ghosh et al., 2008; ghosh and chakrabarti, 2012; hogarth, 2015; tomlinson, 2016). the flowers of family rhizophoraceae display three different pollination mechanisms i.e., rhizophora spp.:wind pollinated, ceriops decandra: insect pollinated and explosive pollen release in ceriops tagal and bruguiera spp. (ghosh et al., 2008; hogarth, 2015; tomlinson, 2016). ghosh and chakrabarti (2012) reported bee, wasp, moth and flies are capable of pollinating in c. decandra. large flowered species of bruguiera are pollinated by birds and small flowered species of acanthus, aegiceras, avicennia, excoecaria, and xylocarpus are probably by butterflies and various types of bees (noske, 1993; hogarth, 2015). some wasps and flies are highly dependent on mangroves for nesting and are particularly important pollinators of c. decandra, kandelia candel and lumnitzera racemosa (tomlinson, 2016). in avicennia marina, the most common visitor was the honeybee, apis mellifera, which is apparently attracted to the nectar-like secretion found toward the base of the corolla tube (clarke and myerscough, 1991). the present study is undertaken to investigate the diversity of insect visitors and their ro le in pollination of twenty two mangroves (i.e., 17 true and 5 associate species) from bhitarkanika wildlife sanctuary and devi estuary (odisha), along east coast of india. 2. methodology 2.1 the study area two mangrove ecosystems, bhitarkanika wildlife sanctuary (bws) and devi estuary (de) of odisha state, along the east coast of india were selected for present study. bws comes under legal protection and a part of it having the mangrove forest is declared also as a national park (86 45 to 87 03 e longitude and 20 30 to 20 48 n latitude) in the view of better protection of mangrove species, with special reference to residing salt water crocodiles (i.e., crocodylus porosus), olive ridley sea turtle (i.e., lepidochelis olivacea) and many other threatened fauna and flora residing inside and in connection to the ecosystem. it is a deltaic ecosystem established in the evolutionary process from deposition of the brahmani and baitarani rivers in rajnagar coastal block of kendrapara district. mangrove of de (86 18 to 86 20 e and 19 57 to 19 58n) is thought to be of recent formation that got established along the river bank of devi (a distributaries of river mahanadi). the climate of these sites is almost tropical and subtropical type. max. rainfall in july-august (200-450 mm) and min. in december-january (0-10 mm); max. temperature in april-may (38 c) and min. in january (15 c) and relative humidity ranges from 60-88 as received data from indian meteorological department (imd, bhubaneswar) for the specified time period. 2.2 data collection twenty two mangal species i.e., 17 true and 5 associates (table 1; supp. table 1 and 2) were selected and study conducted during calendar year of 2016-2017. five flowering twig of each species 80 were pre-marked during flower bud stage. one day visual study was conducted from morning 07.00 am to 13.00 pm during flowering time of each mangrove species. not a single insect was captured or harmed by any means; photographs were taken using the camera, sony alfa slt 58y, dslr (plate 1). insects were identified through experts’ knowledge and using literatures (mani, 1995; chinery, 2007; resh and carde, 2009; singh, 2011; smetacek, 2017). table 1: selected true mangrove and mangrove associates from two sites. true mangroves mangrove associates aegiceras corniculatum (l.) blanco, acanthus ilicifolius l., aegialitis rotondifolia roxb, avicennia alba blume, avicennia marina (forsk.)veierh, avicennia officinalis l. bruuiera cylyndrica (l.) blume, bruguiera sexangula (lour.) poir, bruguiera gymnorrhiza (l) lamk, excoecaria agallocha l., heritiera fomes buch-ham. kandelia candel (l) druce, lumnitzera racemosa wild, rhizophora mucronata lamk. sonneratia apetala buch. – ham., xylocarpus granatum koenig, caesalpinia crista l., cerbera odollam gaertn, excoecaria indica (willd.) mull. arg., salvadora parsica l. tamarix troupii h.  species selected from de pollinating efficacy was determined by comparing dynamic behavior of visitors, i.e., visitation rate (landry, 2013) and resident time with consideration of morpho-structural characteristics of the visited insects. other aspects like, host specificity, host range and pollination syndrome were also studied. rate of visitation (20 min.) = number of particular species (insect)visits number of flowers studied resident time = time spend by visitor on a single visit to a particular flower a jaccard index (cj) was calculated to compare species similarity between the two study sites. 𝐶𝑗 = 𝑎 𝑎 + 𝑏 + 𝑐 where: a=the number of species common to both sites b=the number of species in de, but not in bws c=the number of species in site bws, but not in de 3. results a total of 53 species of insects were identified from flowers of studied mangrove species (table 2; supp. table 1 and 2). the result excludes very small insects that were insignificant of carrying pollens. identified insects belong to 7 orders, 24 families and from 44 genera. the representative orders were coleoptera, diptera, hymenoptera, lepidoptera, orthoptera, hemiptera and odonta (table 2 and figure 1). lepidoptera and hymenoptera showed highest species diversity then others (22 spp. and 18 spp., respectively). diptera and coleoptera had only 5 and 4 species, respectively. two species were from hemiptera and one species each recorded from orthoptera and odonta. out of the total, butterflies:19 spp., bees:8 spp., ants:6 spp., flies:5 spp., wasps and beetles:4 spp. each, moths:3 spp., bugs:2 spp. and one species each of crickets and dragonfly (table 2 and figure 2). the flowers of different mangrove species attract insects but variation exists between host range visited by a specific insect. apis dorsata (honeybee), micraspis discolor (ladybird beetle), crematogastor spp. (ant) and cochliomyia macellaria (flies) had wide host range then others (figure 3). maximum 15 insects were recorded from a. corniculatum and 12 recorded from e. agallocha (figure 4). c. crista, a mangrove associate (climber) was found visited by 9 insects but most of them were moths and butterflies. the result showed flowers of four mangals, a. rotondifolia, a. marina, k. candel and e. indica were visited by eight insects each. only, (1) (2) (3) panda et al. /journal of tropical forestry and environment vol. 9, no. 02 (2019), 78-92 81 3 insect species had been recorded from flowers of h. fomes and b. gymnorhiza (figure 4). among insects, bees were the most frequent visitors and they visited to 18 mangal species (82% of studied mangroves) and particularly “honeybee”, i.e., apis dorsata visited to sixteen mangrove species (i.e., 73% mangroves) (figure 3 and figure 5). dragonfly and crickets were very rare flower visitors. figure 1. insect order wise number of insect species. figure 2. insect group wise number of species. 82 figure 3. showing host range of recorded insects (number of mangrove taxa visited by insects). the comparison of resident time among insect groups showed a large variation. bees and wasps were found more dynamic and frequent flower visitors. similarly, study of visitation rate showed high rate for bees, wasps, flies and butterflies, respectively in comparison with other recorded insect groups (table 3). moths had more residing time on flowers than others. the increasing trend of resident time is as beebutterflywaspfliesdragonflybeetlecricketsbugsantsmoth. figure 4. mangrove species wise recorded number of visited insect species. figure 5: insect group and their visited number of mangrove species. panda et al. /journal of tropical forestry and environment vol. 9, no. 02 (2019), 78-92 83 table 2: recorded insects from mangrove flowers and their classification (spp=species). si.no. name of insect order family insect class 1 apis dorsata hymenoptera apidae bee 2 ceratina simillima hymenoptera apidae bee 3 componotus spp.1 hymenoptera formicidae ant 4 componotus spp.2 hymenoptera formicidae ant 5 componotus spp.3 hymenoptera formicidae ant 6 crematogaster spp.1 hymenoptera formicidae ant 7 crematogaster spp.2 hymenoptera formicidae ant 8 delta campaniforme hymenoptera vespidae wasp (yellow potter) 9 halictus ligatus hymenoptera halictidae bee 10 lasioglossum spp.1 hymenoptera halictidae bee 11 lasioglossum spp.2 hymenoptera halictidae bee 12 nomia spp. hymenoptera halictidae bee (sweet bee) 13 polistes olivaceus hymenoptera vespidae wasp 14 polistes spp. 2 hymenoptera vespidae wasp 15 solenopsis spp. hymenoptera formicidae ant 16 trigona spp. hymenoptera apidae bee 17 vespula vulgaris hymenoptera vespidae wasp 18 xylocopa pubescens hymenoptera apidae bee 19 aulacophora spp. coleoptera chrysomelidae beetle 20 canthon viridis coleoptera scarabaeidae beetle 21 coccinella septempuncata coleoptera coccinellidae beetle (lady bird) 22 micraspis discolor coleoptera coccinellidae beetle (lady bird) 23 amata sperbius lepidoptera arctiinae moth 24 appias lyncida lepidoptera pieridae butterfly 25 atrophaneura latreillei lepidoptera papilionidae butterfly 26 pachliopta aristolochiae lepidoptera papilionidae butterfly 27 catochrysops strabo lepidoptera lycaenidae butterfly 28 catopsilia pyranthe lepidoptera pieridae butterfly 29 chilasa clytia lepidoptera papilionidae butterfly 30 crocidolomia biotalis lepidoptera crambidae moth 31 danaus chrysippus lepidoptera nymphalidae butterfly 32 danaus genutia lepidoptera nymphalidae butterfly 33 euploea core lepidoptera nymphalidae butterfly 34 everes lacturnus lepidoptera lycaenidae butterfly 35 helicoverpa armigera lepidoptera noctuidae moth 36 junonia lemonias lepidoptera nymphalidae butterfly 37 oriens gola gola lepidoptera hesperiidae butterfly 38 papilio demoleus lepidoptera papilionidae butterfly 39 papilio polytes lepidoptera papilionidae butterfly 40 parantica melaneus lepidoptera nymphalidae butterfly 41 precis almana lepidoptera nymphalidae butterfly 42 tirumala limniace lepidoptera nymphalidae butterfly 43 tirumala septentrionis lepidoptera nymphalidae butterfly 44 vanessa cardui lepidoptera nymphalidae butterfly 45 chrysomya megacephala diptera calliphoridae flies 46 cochliomyia macellaria diptera calliphoridae flies 47 eristalinus spp. diptera syrphidae flies 48 rhyncomya spp. diptera calliphoridae flies 49 sarcophaga spp. diptera sarcophagidae flies 50 chrysocoris spp. hemiptera scutelleridae bugs 51 dysdercus spp. hemiptera pyrrhocoridae bugs 52 crocothemis erytbraea odonata libellulidae dragonfly https://en.wikipedia.org/wiki/hymenoptera https://en.wikipedia.org/wiki/ant https://en.wikipedia.org/wiki/ant https://en.wikipedia.org/wiki/ant https://en.wikipedia.org/wiki/ant https://en.wikipedia.org/wiki/ant http://eol.org/pages/648/overview http://www.discoverlife.org/mp/20q?search=hymenoptera http://www.discoverlife.org/mp/20q?search=hymenoptera http://www.discoverlife.org/mp/20q?search=hymenoptera http://www.discoverlife.org/mp/20q?search=hymenoptera https://en.wikipedia.org/wiki/ant https://en.wikipedia.org/wiki/hymenoptera http://www.discoverlife.org/mp/20q?search=hymenoptera https://en.wikipedia.org/wiki/coccinellidae https://en.wikipedia.org/wiki/coccinellidae https://en.wikipedia.org/wiki/lepidoptera https://en.wikipedia.org/wiki/lepidoptera https://en.wikipedia.org/wiki/lepidoptera https://en.wikipedia.org/wiki/lepidoptera https://en.wikipedia.org/wiki/lepidoptera https://en.wikipedia.org/wiki/lepidoptera https://en.wikipedia.org/wiki/lepidoptera https://en.wikipedia.org/wiki/lepidoptera https://en.wikipedia.org/wiki/lepidoptera https://en.wikipedia.org/wiki/lepidoptera https://en.wikipedia.org/wiki/lepidoptera https://en.wikipedia.org/wiki/lepidoptera https://en.wikipedia.org/wiki/lepidoptera https://en.wikipedia.org/wiki/lepidoptera https://en.wikipedia.org/wiki/lepidoptera https://en.wikipedia.org/wiki/lepidoptera https://en.wikipedia.org/wiki/lepidoptera https://en.wikipedia.org/wiki/lepidoptera https://en.wikipedia.org/wiki/lepidoptera https://en.wikipedia.org/wiki/lepidoptera https://en.wikipedia.org/wiki/lepidoptera https://en.wikipedia.org/wiki/lepidoptera https://en.wikipedia.org/wiki/diptera https://en.wikipedia.org/wiki/dragonfly 84 53 metrioptera spp. orthoptera tettigoniidae crickets table 3: resident time and visitation rate of each insect class. flower visitors resident time (s) (meanse) visitation rate (m) (meanse) bee 14.172.11 35.835.68 beetle 34.673.28 4.171.23 flies 23.083.42 5.331.25 wasp 20.581.96 6.001.47 butterflies 19.922.01 3.600.66 ant 53.754.83 2.670.67 moths 97.0012.27 2.400.66 bugs 50.174.04 3.000.82 dragonflies 28.002.56 2.500.41 crickets 45.672.31 1.670.33 4. discussion mangrove flowers are not much eye-catching as like many terrestrial angiosperms. they also lack significant provisions in the form of pollinator rewards. in comparison to other forest or garden plants, few and specific insects do pollination in mangroves. mangrove community contains species that are both generalists and specialists (azuma et al., 2002). our result showed similarity with many previous studies on aspects of pollinator diversity and role in mangrove species pollination (clarke and meyerscough, 1991; pandit and choudhury, 2001; azmi et al., 2012; raju et al., 2012; raju et al., 2014, hermansen et al., 2014; tomlinson, 2016). the report towards visitation of ants, wasp, bugs, flies, bees, cantharid beetles and moths to flowers of a. marina by clarke and meyerscough (1991) showed similarity to this study. hermansen et al. (2014) identified 38 species that visited to flowers of a. marina but only a. mellifera was a significant pollinator. we found a. dorsata as a potential pollinator of 16 mangrove species under our study. they had not reported butterfly visits which had been recorded during this particular investigation. in l. racemosa, three groups of flower visitors were found which include bees, wasps and butterflies (raju et al., 2014). our study had recorded beetle and ant visitation along with bees and butterflies from flowers of l. racemosa. k. candel is a riverine mangrove, occur along the river banks and influenced by freshwater input. the flowers of this plant produce a chemical (methyl anthranilate) that is known to repel species of birds and insects like bees and butterflies (azuma et al., 2002). we recorded beetle, wasp and moth along with previously recorded bee and butterflies from flowers of k. candel. pandit and choudhury (2001) studied a 3 day (both day and night) flower visitors of mangrove species, a. corniculatum and s. ceseolaris at bhitarkanika. they recorded 17 species of lepidoptera, 7 species of hymenoptera, 3 species of diptera, 5 species of birds and 3 species of mammals from s. ceseolaris and 16 species of lepidoptera, 9 species of hymenoptera, 2 species of diptera, 1 species of coleoptera and 3 species of birds from a. corniculatum. the genus, ‘bruguiera’ show specialised pollination through birds. they have large flowers and peculiar tube shape which attracts birds. in b. gymnorrhiza, the calyx is red, a colour attractive to birds (tomlinson, 2016). in this particular study we recorded wasp, bee and ant visitation to b. sexangula; bee and ant from b. gymnorhiza (table 4). bees because of their structural adaptations for the collection of pollen are considered to be the most efficient pollinators (abrol, 2012). bees as a flower visitor have been observed in many species of the genera like, acanthus, aegiceras, avicennia, excoecaria, rhizophora and xylocarpus (tomlinson, 2016). xylocopa varipuncta (carpenter bee) has been identified to carry pollens of exclusive mangroves like, a. alba, l. racemosa, s. caseolaris, s. ovata and r. apiculata in the mangrove community of setiu wetlands, terengganu (azmi et al., 2012). bumble bee visited flowers show increased seed set than when plant excluded from it (miller-struttmann, 2017). carpenter bees have long tongue which gathers mainly panda et al. /journal of tropical forestry and environment vol. 9, no. 02 (2019), 78-92 85 pollen, but not nectar. carpenter bee is one among the most efficient agents for cross pollination in mangrove flowers (mani, 1995). we found it’s strong association with flowers of e. agallocha and a. corniculatum (plate 1). this bee is very dynamic and flies actively back and forth to flowers which help in pollen dispersal and deposition. the sweet bees (lasioglossum spp.) are recorded from mangroves like, a. corniculatum, a. rotondifolia, b. gymnorhiza, k. candel and r. mucronata (supp. table 1). they were regular visitors in flowers of a. corniculatum (plate 1). their hind legs help and make them a good candidate for pollen dispersal. comparison of host range showed bee, ant, beetles, butterfly, flies and wasps were more general flower visitors than moths, bugs, crickets and dragonfly which were rare and occasional visitors (figure 5). previously, no beetle pollinated flowers had been recorded from mangroves, which are considered to be “primitive” pollinators and typically associated with large flowers or inflorescences of much generalised type (tomlinson, 2016). this particular study had recorded lady bird beetle (micraspis discolor) visitation from 12 mangroves (54%) and thought to have a major contribution and bringing pollination in species like a. corniculatum, b. cylindrical, s. apetala, a. ilicifolius, c. decandra and k. candel (figure 3, plate 1). r. mucronata primarily wind pollinated but insect visitation also reported which supports our work. table 4: mangrove species and their flower visitor class identified in the present study. true mangroves visitor class true mangroves visitor class 1 a. corniculatum (l.) blanco bee, flies, wasp, beetle, ant, bird 13 k. candel (l) druce bee, beetle, wasp, butterfly, moth 2 a. ebracteatus vahl. bee, beetle, wasp, moth, spider 14 l. racemosa willd. bee, beetle, ant, butterfly, bird 3 a. ilicifolius l. bee, beetle, butterfly, ant, spider, bird 15 r. mucronata lamk. bee, beetle, ant 4 a. rotondifolia roxb. bee, wasp, ant 16 s. apetala buch. ham. beetle, moth, bird 5 a. alba blume bee, beetle, dragonfly, flies, butterfly 17 x. granatum koenig bee, beetle, moth, bugs, ants, bird 6 a. marina (forsk.)veierh bee, beetle, moth, flies, wasp, butterfly, bird mangrove associates 7 a. officinalis l. bee, beetle, ant, flies, butterfly, bird 18 c. crista l. butterfly, crickets, moth, bird 8 b. cylyndrica (l.) blume beetle, ant, flies 19 c. odollam gaertn ant, butterfly, moth, 9 b. sexangula (lour.) poir bee, ant, wasp, bird 20 e. indica (willd.) mull. arg. bee, flies, ants, butterfly, bugs 10 b. gymnorrhiza (l) lamk bee, ant, bird 21 s. parsica l. bee, beetle, flies, ant, bird 11 e. agallocha l. bee, wasp, flies, bugs, butterfly 22 t. troupii h. bee, butterfly, bird 12 h. fomes buch-ham. bee, ant, spider ant and honey bee visitation to flowers of h. fomes showed their role in pollination of this south asian endemic species. high resident time indicates it to be a forging species. an insect having high visitation rate and low resident time is a good pollinator (landry, 2013). our study showed, bees, butterflies, and wasps are efficient mangrove pollinators with low resident time and high visitation rate (table 3). the species of former group with highest visitation rate, low resident time and with structural adaptation placed them a potential candidate in bringing mangrove pollination. bugs, moths and ants were forging species and contribute little to the mangrove pollination as lack structural adaptation to carry pollens from flowers. we reviewed literature of eighteen mangrove species that showed all species were more or less associated with biotic pollinators like insects more commonly from family hymenoptera, diaptera, coleoptera and lepidoptera (marshall, 1983; clarke and meyerscough, 1991; raju et al., 1994; sun et al., 1998; naskar and mandal, 1999; pandit and choudhury, 2001; raju et al., 2006; ghosh et al., 2008; nagarajan et al., 2010; ghosh and chakraborti, 2012; raju et al., 2012; pandey and pandey, 2013; hermansen et al., 2014; raju and raju, 2014; raju et al., 2014; tomlinson, 2016) (table 5). the latter two groups spend enough time for nectar foraging. mangrove flowers are not much attractive but still able fascinate few unique insects that bring successful pollination. 86 the work of faegri and pijl (1979) and abrol (2012) on pollination syndrome (characters which attracts or favors for pollination) also supported our findings (table 6). the yellow/brown coloured flower of avicennia sp. and b. sexangula; blue colour in a. ilicifolius are commonly visited by bees. white flowered species of a. corniculatum and a. rotondifolia with ample nectar were found to be frequently visited by bees, i.e., honeybee and losioglossum spp. (supp. table 1; plate 1). thus, attracting pollinators is a prerequisite for reproductive success in angiosperms (moyroud and glover, 2017). past work showed the genus, sonneratia have night blooming flowers which attract bats for foraging and pollination (table 5). beetle and moth visits to flowers of sonneratia spp. had been recorded from this study (table 4). butterfly visitation to t. troupii; flies visitation to e. agallocha and e. indica; beetle visitation to a. corniculatum, a. rotondifolia, k. candel and r. mucronata etc., bird pollination in b. sexangula and b. gymnorhiza; moth visitation of mangrove associates like, c. odollam and c. crista; ant visits to a. corniculatum and a. rotondifolia, x. granatum and h. fomes were supported by previous studies on pollination syndrome (faegri and pijl, 1979; abrol, 2012). table 5: result of literature review showing studies on flower visitors and pollinators of different mangrove species. mangrove wind insect bird bats (h/d/c) butterfly (l) a. corniculatum (l.) blanco 3, 5, 6, 12 6, 12 6, 12 a. rotondifolia roxb. 5 a. illicifolius l. 3 3 a. alba blume 11 11 a. marina (forsk.)veierh 2, 10, 11, 13 2 a. officinalis l. 3,11 11 r. mucronata lamk. 3,5,8,16 8*, 10 b. cylindrical (l.) blume 16 3, 5 b. gymnorhiza (l.) lamk. 9 3, 5, 16 b. sexangula (lour.) poir 9 3, 5, 16 c. crista l. 5,14 14 c. decandra (griff.) ding hou 8, 7, 10, 16 e. agallocha l. 5 k. candel (l) druce 3, 4, 5, 16 4, 5 l. racemosa willd. 3, 15, 16 15 sonneratia sp. 1, 16 x. granatum koenig 5* h. fomes buch.-ham. 5* note: 1: marshall, 1983; 2: clarke and meyerscough, 1991; 3: raju et al., 1994; 4: sun et al., 1998; 5: naskar and mandal, 1999; 6: pandit and choudhury, 2001; 7: raju et al., 2006; 8: ghosh et al., 2008; 9: nagarajan et al., 2010; 10=ghosh and chakraborti, 2012; 11: raju et al., 2012; 12: pandey and pandey, 2013; 13: hermansen et al., 2014; 14: raju and raju, 2014; 15: raju et al., 2014; 16: tomlinson, 2016 [h: hymenoptera, d: diaptera, c: coleoptera, l: lepidoptera and =honeybee, = bumble bee] among the four bee species i.e., honey bee, carpenter bee, sweet bee and bumble bee, we observed that honey bees were more common and visited inflorescence in group. a single inflorescence of salvadora parsica was noted to host approximately about 10-15 honey bees at a particular time. similar results were recorded from mangroves like, a. corniculatum, a. marina and b. sexangula. carpenter bees were the second most sociable after honey bees and recorded in groups of approximately 3-4 from the flowers of a. corniculatum and e. agallocha. bumble bee and sweet bee were rare and single individuals had been recorded from the visited flowers. during this particular work we noted anti-herbivory role of micraspis discolor (ladybird beetle) which prevents leaf herbivory and damage in many mangrove species. leaf area loss by herbivores is a common phenomenon in mangroves like genera avicennia, kandelia, cerops and rhizophora. presence of micraspis discolor on mangrove leaves protect leaves from herbivory damages along with play a critical role in pollination (plate 1). honey bee not only brings panda et al. /journal of tropical forestry and environment vol. 9, no. 02 (2019), 78-92 87 successful pollination, it also supports the earnings of local livelihood through high quality honey production. about 200 tons of honey and 50 tons of beeswax are harvested annually from reserve forest of sundarbans (gani, 2001). this is 50 percentage of total honey production of bangladesh. in bhitarkanika, honey is collected by the local people largely to sell in the market as resource for their livelihood (hussain and badola 2010). 88 table 6: pollination syndromes: traits of flowers pollinated by different pollinators, (adapted after, faegri and pijl, 1979; abrol, 2012). pollinator class floral morphology colour scent nectar tube primary attractants toughness floral opening insects (entomophily) differs with type of pollinators yes yes yes not enough day and night bees (melitophily) zygomorphic with great depth effect, mechanically strong adequate landing facility blue, yellow, purple (except red) sweet smell nose size or long body width nectar hidden deep; sucrose rich; abundant pollen not enough, have a landing platform or lip day and night flies (myophily) actinomorphic, regular, simple, funnel-like light or dull, whitish imperceptible open cups nectar not tough day and night butterflies (psychophily) actinomorphic, flowers in group, erect radial, good landing facilities dull brown, white, blue and purple weak long narrow nectar in ample quantities, hidden at base of pollen tubes not tough, no landing platform day and night moths (phalaenophily) actinomorphic or zygomorphic, horizontal pale, purple, white strong sweet, nocturnal long narrow nectar in large but hidden in tubes not tough, no landing platform night ants (myrmecophily) small, sessile, close to ground white, purple, blue faint hidden deep nectar and pollen -----------day and night beetles (cantharophily) actinomorphic, large shallow, often bowl shaped blossoms dull white, purple or brown strong fruity no mostly pollen, sometimes nectar not enough day and night wasp (sphecophily) dull brown nectar day and night birds (ornithophily) large container like, tubular or funnel like strong supports for perch. red, yellow or orange no (birds can’t smell) long wider nectar, insects sitting flower, rarely pollen tough, leathery, plenty of nectar day and night wind (anemophily) regular, small, unisexual (either monoecious or dioecious species), highly reduced perianth, anthers and stigmas exerted yellow or brown, may be absent or reduced no no ------not tough, big anthers, plenty of pollen. stigmas feathery to catch the pollen day and night  from present study panda et al. /journal of tropical forestry and environment vol. 9, no. 02 (2019), 78-92 89 plate 1: flower visitors and presumed pollinators in different mangrove species of bws and de. [note: 1-4: a. dorsata (giant honey bee) on flowers of a. rotondifolia, r. mucronata, s. parcica and a. officinalis, respectively; 5: vespula sp. on flower of a. rotondifolia; 6-7: euploea core and tirumala limniace on flowers of t. troupii, respectively; 8: lasioglossum sp.1 on flower of a. corniculatum; 9-10: lasioglossum sp.2 on flower of a. corniculatum; 11: amata sperbius feeding on flowers of x. granatum; 12: xylocopa pubescens visiting flowers e. agallocha; 13: nomia sp. on e. indica; 14: micraspis discolor sitting on flower of a. corniculatum; 15 & 16: dysdercus sp. (bug) & ant visitation on flowers of x. granatum, respectivly; 17: a bug (aulacophora sp.) sitting 1 2 3 4 8 7 6 5 11 10 9 14 13 12 15 16 17 18 19 90 on a. corniculatum; 18: herbivory of mangrove leaves; 19: undamaged leaves in presence of micraspis discolor on k. candel] 5. conclusion mangroves are exclusively seed propagated plants. excluding rhizophora spp. which bears predominantly wind pollinated mangroves, all other species more or less depend on biotic agents/pollinators for effective pollen transfer. habitat degradation, conversion to aquaculture land, use of pesticides in agriculture, introduction of exotic plant species are strongly affecting the existence and action of natural pollinators. ‘bhitarkanika’ being the second large single mangrove patch in india, presently experiencing loss of species diversity for which it was previously known throughout the globe. impact of climate change on pollinator availability and specialist pollination in mangroves can further studied towards effective management of fragile ecosystem like mangrove. giving more emphasis on bee keeping can help to increase the reproductive success and seed output in many mangroves. not only the honey bee but others like carpenter bee (xylocopa spp.), sweet bee (lasioglosum spp.) may need to be given priority for increase of their population. conservation of associate mangrove species will give additional advantage to maintain true mangrove diversity as they provide alternative forage during non flowering period of true mangrove species. making policies and law to prevent use of harmful chemicals in peripheral agriculture land will help to prevent further loss of these natural pollinators. the anti-herbivory role of the predatory ladybird beetle and effect of climate change on pollinator availability in this fragile coastal ecosystem may be further investigated and can be used towards long term management. acknowledgment we are thankful to pccf, wildlife (odisha), dforajnagar and staffs of mangrove forest division of bws for their support and valuable contribution during our field survey. references abrol, d.p., 2012. pollination biology: biodiversity conservation and agricultural production. springer science, 792. alongi, d.m., 2009. the energetics of mangrove forests. springer science, 216. azmi, w.a., ghazi, r. and mahamed, n.z., 2012. importance of carpenter bee, xylocopa varipuncta (hymenoptera: apidae) as pollination agent for mangrove community of setiu wetlands, terengganu, malaysia. sains malaysiana, 41:1057-1062. azuma, h., toyota, m., asakawa, y., takaso, t. and tobe, h., 2002. floral scent chemistry of mangrove plants. journal of plant research, 115:47-53. capinera, j.l., 2010. insects and wildlife: arthropods and their relationships with wild vertebrate animals. john wiley and sons ltd., 487. chinery, m (2007). insects of britain and western europe. domino books ltd., 320. clarke, p.j. and meyerscough, p.j., 1991. floral biology and reproductive phenology of avicennia marina in south eastern australia. australian journal of botany, 39:283-293. faegri, k. and pijl, l., 1979. the principles of pollination ecology. pergamon press ltd., 244. gani, m.o., 2001. the giant honey bee (apis dorsata) and honey hunting in sundarbans reserved forests of bangladesh. in: proceedings of 37th international apiculture congress, held in 28th oct.-1st nov., 2001, durban, south africa, 1-10. ghosh, a. and chakraborti, p., 2012. evaluation of some mangrove species on the nature of their reproduction along coastal belt of the indian sunderbans. journal of threatened taxa, 4:24272435. ghosh, a., gupta, s., maity, s. and das, s., 2008. study of floral morphology of some indian mangroves in relation to pollination. research journal of botany, 3:9-16. panda et al. /journal of tropical forestry and environment vol. 9, no. 02 (2019), 78-92 91 hermansen, t.d., britton, d.r., ayre, d.j. and minchinton t.e., 2014. identifying the real pollinators? exotic honeybees are the dominant flower visitors and only effective pollinators of avicennia marina in australian temperate mangroves. estuaries and coasts, 37:621-635. hogarth p.j., 2015. the biology of mangroves and seagrasses. oxford university press, new york, 289. hussain, s.a. and badola, r., 2010. valuing mangrove benefits: contribution of mangrove forests to local livelihoods in bhitarkanika conservation area, east coast of india. wetlands ecology and management, 18:321-331. jagtap, t.g., chavan, v.s. and untawale, a.g., 1993. mangrove ecosystems of india: a need for protection. ambio, 4:252-254. kathiresan, k. and bingham, b.l., 2001. biology of mangroves and mangrove ecosystems. advance in marine biology, 40:81-251. kearns, c.a. and inouye, d.w., 1997. pollinators, flowering plants, and conservation biology: much remains to be learned about pollinators and plants. bioscience, 47:297-307. landry c.l., 2013. pollinator-mediated competition between two co-flowering neotropical mangrove species, avicennia germinans (avicenniaceae) and laguncularia racemosa (combretaceae). annals of botany, 111:207-214. mani m.s., 1995. insects. national book trust, india, 162. marshall a.g., 1983. bats, flowers and fruit: evolutionary relationships in the old world. biological journal of the linnean society, 20, 125-135. miller-struttmann, n.e., heise, d., schul, j., geib, j.c. and galen, c., 2017. flight of the bumble bee: buzzes predict pollination services. plos one, 12:1-14. mitra, b., biswas, o., roy, s. and chakraborti, u., 2013. pollinators of mangroves in the perspective of indian sundarbans. envis newsletter, 21:6-11. moyroud, e. and glover, b.j., 2017. the physics of pollinator attraction. new phytologist. 216: 350-354. nagarajan, m., krishnamoorthy padmini, s. and daniel, a., 2010. nectar robbery in bird pollinated mangroves! current science, 98:603-604. naskar, k. and mandal, r., 1999. ecology and biodiversity of indian mangroves. daya publishing house, delhi, vol. i and ii, 754. noske, r.a., 1993. bruguiera hainesii: another bird-pollinated mangrove? biotropica, 25:481-483. pandey, r. and pandey, c.n., 2013. spatial and temporal variations in floral visitors of a mangrove species-aegiceras corniculatum (l.) blanco-in the marine national park, gujarat, india. international journal of botany and research, 3:35-42. pandit, s. and choudhury, b., 2001. factors affecting pollinator visitation and reproductive success in sonneratia caseolaris and aegiceras corniculatum in a mangrove forest in india. journal of tropical ecology. 17:431-447. pratap, u., 2011. the pollination role of honeybees. in: honeybees of asia, ed. h.r. hepburn and s.e. radloff, berlin, springer science, 227-255. raju, a.j.s., 1990. studies on pollination ecology in india: a review. proceedings of indian national science academy, b56, 4:375-388. raju, a.j.s., jonathan, k.h. and lakshmi, a.v., 2006. pollination biology of ceriops decandra (griff.) ding hou (rhizophoraceae), an important true viviparous mangrove tree species. current science. 91:1235-1238. raju, a.j.s., kumar, r. and rajesh b., 2014. pollination ecology of lumnitzera racemosa willd. (combretaceae), a non-viviparous mangrove tree. taprobanica, 6:100-109. raju, a.j.s., rao, p.v.s., kumar, r. and mohan, s.r., 2012. pollination biology of the crypto-viviparous avicennia species (avicenniaceae). journal of threatened taxa. 4:3377-3389. 92 raju, a.j.s., reddi, c.s. and sujatha, b., 1994. pollination in mangrove plants. journal of natcon, 6:8996. raju, p.s. and raju, a.j.s., 2014. pollination ecology of the gray nicker caesalpinia crista (caesalpiniaceae) a mangrove associate at coringa mangrove forest, andhra pradesh, india. journal of threatened taxa, 6:6345-6354. resh, v.h. and carde, r.t. (ed.), 2009. encyclopedia of insects. elsevier, inc., 1132. robertson, a.i., 1991. plant-animal interactions and the structure and function of mangrove forest ecosystems. australian journal of ecology. 16:433-443. singh, a.p., 2011. butterflies of india. om books international, 183. smetacek, p., 2017. a naturalist’s guide to the butterflies of india. john beaufoy publishing limited. 176. sun m., wong k.c. and lee j.s.y., 1998. reproductive biology and population genetic structure of kandelia candel (rhizophoraceae), a viviparous mangrove species. american journal of botany. 85:1631-1637. tomlinson, p.b., 2016. the botany of mangroves. cambridge university press, cambridge, uk, 418. kaba et al. /journal of tropical forestry and environment vol 12, no. 02 (2022) 10-21 correspondence: gkabaa17@gmail.com issn 2235-9362 online ©2022 university of sri jayewardenepura. 10 density and seasoning characteristics of pinus caribaea lumber grown at suba forest, oromia, ethiopia gemechu kaba1*, getachew desalegn1, antenehtesfaye1, mahadi mussa1, tsegaye wubshet1 and getachew mezgebu1 1forest products innovation center, ethiopian forest development, addis ababa, ethiopia *gkabaa17@gmail.com date received: april 30, 2022 date accepted: october 03, 2022 abstract determination of the seasoning characteristics, physical and mechanical properties of lumber species is helpful in identifying the main factors affecting the quality, suitability and overall performance of wood and wood-based products. the pinus caribaea has been considered as industrial lumber species and there is a little study conducted in identifying the physical characteristics which on turn affects the quality of product derived from the lumber. therefore, this study aimed at evaluating the density and seasoning characteristics of p. caribaea lumber. sample trees were harvested from suba forest oromia, ethiopia. the experiments were carried out using air and kiln seasoning methods. to measure the initial moisture content, seasoning rate, shrinkage, wood density, and seasoning defects, six replicates of samples from each tree portions were prepared when green and promptly weighed. analysis of variance (anova) has been employed in interpreting the experimental results. the obtained results have shown that the mean initial moisture content for air stacks was 78.2% while for the kiln seasoning stacks 82.9%. seasoning time for sawn boards of 3 cm thick to reach 17% moisture continent (mc) required 61 days, while for kiln seasoning took 4.3 days to reach 14.62% mc. this showed that kiln seasoning was about 14 times faster than air seasoning. in air seasoning the mc (%) of the lumber from 78.2% to 16.9%; and, the obtained mean values of shrinkages were tangential (3.6%), radial (1.9%) and volumetric (5.4%). the initial moisture content (imc) and green density (gd) of the lumber were significant difference along the tree height at a 95% probability level. the seasoning rate % and final mc (%) along the tree height were significant difference at 95% probability level, while the seasoning rate % and final mc were significant difference between seasoning methods at 99% probability level. seasoning defects such as cup, bow, twist, and crook were observed on kiln seasoned. in addition, end checks and splits were observed on air seasoned boards. therefore, the experimental factors should be monitored and optimized properly to obtain the lumber with good quality and utilize it for different purposes, including construction and industrial applications. keywords: density, lumber, moisture content, seasoning, shrinkage characteristics, pinus caribaea 1. introduction in ethiopia, the demand for wood-based products in 2017 was measured in terms of equivalent volume of consumed round wood and it was estimated to be 114 million cubic meters (un-fao, 2019). the demand and supply of industrial round wood in ethiopia were 7.4 and 3 million m3, respectively (ministry of environment, forest and climate change [mefcc], 2018; united nations food and agricultural organization [un-fao], 2019). this shows there is a kaba et al. /journal of tropical forestry and environment vol 12, no. 01 (2022) 10-21 11 wide gap between the demand and supply. the gap is being filled by imported lumber and unsustainable harvesting and utilization of natural and plantation forests (environment, forest and climate change commission [efcc], 2020); and this could jeopardize the natural ecosystem and biodiversity thereby inducing overexploitation of the dwindling forest resources. moreover, the potential lumber species have been introduced and planted continuously all over the country to fill the gap and bring about sustainable utilization of the country’s plantation forests and woodlot resources (gemechu et al., 2018). among these tree species, pinus caribaea is a well-known and substantial industrial lumber species that has been planted and adopted in ethiopia to achieve the goal of plantation development and sustainable utilization of forest resources (mebrate, 2006). the p. caribaea (family pinaceae) is an evergreen, monoecious, and medium-sized tree that is 20 45 m in height, 60-135 cm in diameter and bole branchless of 21 m. p. caribaea is fast growing species with a mean annual volume increment of 10 40 m³/ha and 15-25 years rotation for sawn wood, veneer, large posts and pulpwood. the wood properties of p. caribaea shows variations as heavy, hard, narrow ringed and resin saturated at one end of the spectrum to soft, light, wide ringed and almost lacking in latewood and resin at the other end. the tree is usually straight, cylindrical, bark surface reddish brown to pale brownish grey, inner bark very resinous, crown thin, rounded to pyramidal, slightly spreading, twigs orange brown, later turning gre ybrown (oteng-amoako and brink, 2008; orwa et al., 2009). furthermore, p. caribaea is grown in 1000 -1500 m altitude above sea level (asl), in areas with a mean annual temperature of 20 27°c, an average annual rainfall of 650-4000 mm, and a dry season of up to 6 months. the tree is moderately tolerant to wind and can be planted near the coast. it grows on a wide variety of soils like loams or sandy loams, sometimes with high amounts of gravel and generally well drained (oteng-amoako and brink, 2008; orwa et al., 2009). according to some authors the species is native to the caribbean area, cuba, honduras, bahamas and colombia, guatemala, mexico, nicaragua and panama. as an exotic plantation species p. carebea is planted fairly widely in australia, brazil, canada, india, indonesia, united states of america, venezuela, south, east, east west and central parts of african countries including ethiopia (orwa et al., 2009). the effective, efficient and sustainable utilization of the lumber species (i.e., p. caribaea) necessitated adequate knowledge and deep understanding of its natural variations, density and seasoning characteristics, physical and mechanical characteristics and its industrial applications (nascimento et al., 2018). hence, generation of appropriate technological information regarding the tree seasoning and the selection of suitable utilization method is of prime importance while enhancing the service life of the product(s). in light of this explanation, the intended study was carried out to generate technical information (i.e., density and seasoning characteristics) and selecting appropriate methods for utilization of the lumber species, p. caribaea, grown at suba forest of oromia forestry and wildlife enterprise (ofwe), ethiopia. 2. materials and methods 2.1 description of the study site sample trees of p. caribaea were harvested at the age of 44 from suba forest of ofwe. suba forest is located 40 km west of addis ababa and lies within longitude and latitude coordinates of 38°31’– 39’e and 08°54’n–09°04’n, respectively, and the altitude ranges between 2330 and 3300 m asl. the mean annual rainfall of 1100 mm and the mean temperatures (min and max) are 15 c° and 22c°, respectively. the tree species is originated from the bossum provenance of kaba et al. /journal of tropical forestry and environment vol 12, no. 01 (2022) 10-21 12 holland and currently available in ethiopia at belete, hamulo and menagesha -suba (mebrate mihreiu, 2004; mebrate mihertu, 2006) 2.2 trees harvesting and test samples preparation twelve sample trees with good morphological characteristics and free from visible defects were selected, harvested and cross-cut into a series of 5 m long logs up to top merchantable diameter of 20 cm. the selected trees have a mean height of 22 m and 30 cm diameter. harvested logs while green (> 30% mc) were transported to laboratory of forest products innovation center (fpic), addis ababa, for the preparation and testing samples. logs were flat sawn to 3 cm thick boards and converted to samples with appropriate dimensions for each wood characteristic (moisture content, seasoning rate, seasoning defects, shrinkage and density) tests following the iso standards (iso 3129, 1975; iso 3130, 1975; iso 3131, 1975; denig et al., 2000; fpl, 2010; moya et al., 2013). 2.3 lumber stacking for air and kiln seasoning sawn boards from sawmill area were transported to the air seasoning yard and kiln seasoning chamber areas (figure 1). boards were sorted according to their thickness, width, and types (heart, sap, tangential and radial boards). then, lumber stacked horizontally in vertical alignments separated by wellseasoned standard stickers. stickers were put at equal distance (75 cm across each layer of lumber) and aligned vertical board on board from bottom of the stack to the top. while stacking boards, care was taken to ensure free circulation of fre sh air all around each stack and board. in addition, the control sample boards were distributed properly and positioned in the pockets of the different layers (i.e., bottom, middle and top) of each stack to represent the different zones/layers in the stack (figure 1). figure 1: air seasoning stack (1a) and kiln seasoning stack (1b) at the entrance of the kiln chamber boards for air seasoning were stacked on firm level foundation 45 cm above the ground, under open-sided shed without direct exposure to moisture, rainfall and sunshine (figure 1a). the boards were aligned in a north-south direction where the ends were not exposed to the direction of the wind. boards for kiln seasoning were stacked out of the kiln on the transfer carriage having dimensions of 1.6 m width, 0.30 m height and 2.7 m length and then placed in the kiln-seasoning chamber by sliding the stack on the rail (figure 1b). top loading (heavy stones) weighing about 50 kg/m2 was applied on top of the air and kiln seasoning stacks to minimize warping of the boards as seasoning progresses. the kiln schedule adapted from kaba et al. /journal of tropical forestry and environment vol 12, no. 01 (2022) 10-21 13 boone et al. (1988) having a serious of temperature and relative humidity at different corresponding mc levels was applied (table 1) table 1: the employed kiln schedule step moisture content (%) dry-bulb temperature (°f) wet-bulb temperature (°f) relative humidity (%) equilibrium moisture content (%) 1 above 50 60 56 82 14.2 2 50 to 40 60 54.5 75 12 3 40 to 35 60 51.5 64 9.6 4 35 to 30 60 49 55 8 5 30 to 25 65.5 51.5 49 6.8 6 25to 20 71 54.5 43 5.8 7 20 to 15 76.5 57 39 5.1 8 15 to final 82 54.5 26 3.5 source: boone et al., 1988. 2.4 lumber characteristics determination initial moisture content determination six replicates of samples from each tree portion were prepared while green and immediately weighted to determine initial moisture content of the stack. a well -ventilated oven machine/ chamber with trays having open grids was used to allow free air circulation around the test pieces while keeping the seasoning temperature constant at 105°c. drying and re-weighing of samples was carried out continuously at four hours interval until the difference between two successive weights of each specimen became constant (0.000 0.200 g) and the final weights were taken as the ovendry weights (iso 3130, 1975; fpl, 2010). afterwards, the moisture content of air and kiln seasoning stacks were determined using the following formula. 𝑀𝐶 (%) = ( green weight−oven dry weight oven dry weight ) × 100 (1) after initial mc determination, the control sample boards were weighed, analytically determined oven dry weights were calculated and the control samples placed into the stack. during air seasoning the control samples were re-weighed at a week interval until the average final moisture content of the stack reached final moisture content (about 12%), which is the equilibrium moisture content for in-and out-door purposes and standard for comparison within and between lumber species. during kiln seasoning test, samples were weighed, moisture content was calculated, psychrometers were regulated, steaming was done, and the direction of the fan changed at 8 hours interval (i.e., three times in 24 hours) to allow uniform air circulation. the process was continuous until the final mc reached. this is used to control the seasoning process and maintain the quality of seasoned lumber (fpl, 2010; moya et al., 2013). rate of seasoning determination air and kiln seasoning rates of the species was estimated from the mc samples of the species. seasoning rate (%/hour) = imc-fmc (%)/drying time (hour) (loulidi i. et al., 2012) where, imc-initial moisture content and fmcfinal moisture content. the air and kiln seasoning rates classification lumber for the lumber was done based on the adapted literatures (longwood, 1961; farmer, 1987). kaba et al. /journal of tropical forestry and environment vol 12, no. 01 (2022) 10-21 14 shrinkage characteristics determination twenty samples of the lumber species with the dimension of 2x2x3 cm (iso/dis 4469, 1975) were seasoned in the oven machine at the temperature of 105c until a constant weight was obtained for each sample. initial dimensions and weights of all the shrinkage samples were measured and put in the oven. measurements of weights were continuous until the difference between the two successive weights of each specimen was constant (0.000 0.200 g). then, the final weights were taken as oven dry weights and final dimensions were measured shrinkage of each specimen at tangential, radial, longitudinal directions and volumetric were determined from green condition to 12% mc and from green to 0% mc using the formula in (equation 2): shrinkage% = (change in dimension green dimension x 100) (2) finally, the rate of tangential shrinkage to radial shrinkage (coefficient of anisotropy) was calculated to know the tendency of the species to present warping, cracking and splitting during seasoning. according to acosta et al (2008) the higher this ratio from the value of one will be the higher to present these defects during seasoning of the wood. density determination the sampling procedures and measurements applied during shrinkage experiments as stated earlier were used to determine the density values of the species using mathematical formulas at different mc and sample conditions (i.e., green, oven dry and seasoned to 12% mc). basic density was determined based on green volume and oven dry weight (iso/dis 3131, 1975). the dry density values were converted to standard 12% equilibrium mc (table 2) by applying the formulas adapted from (iso/dis 3131, 1975; denig et al., 2000; reeb and brown, 2007; fpl, 2010; moya et al., 2013). density value of the species at 12% mc was classified based on the adapted standard classification from farmer (1987). seasoning defects determination natural, initial and after seasoning defects of lumber species including knots, cup, bow, twist, end split, end and surface checks were measured and determined using digital caliper, ruler and tape meter. seasoned boards were properly piled in the air seasoning yard, board on board, without stickers between them. boards were handled and conditioned well without direct exposure to moisture and sunshine to avoid/minimize dimensional movement (shrinkage and swelling), seasoning defects and biodegradation attack. 2.4 data analysis the measurements of dimension (length, width and thickness) and weight were helped to determine the following parameters: (i) moisture content (%) at green, current and final, (ii) density (gm/cm3) at green and air-dry conditions, (iii) rate of seasoning (%/day), (iv) shrinkage (%) from green to 12% mc and green to 0% mc in tangential, radial and longitudinal directions and volumetric, and (v) initial and seasoning defects (observation and measurements). analysis of variance (anova) for shrinkage, density and seasoning characteristics was performed at 95% confidence interval. significant differences among tree height were determined by duncan’s homogeneity groups. statistical analysis was performed using the statistical package for the social sciences (spss) 20 version. 3. results and discussion kaba et al. /journal of tropical forestry and environment vol 12, no. 01 (2022) 10-21 15 3.1 lumber appearance the wood of p. caribaea showed different lumber characteristics. the lumber appearance revealed the creamy white sapwood and the dark brown heartwood (figure 2a). figure 2: appearance (a) and high resin content (b) from p. caribaea lumber 3.2 moisture content the mean initial moisture content of p. caribaea lumber was 78.2% for air seasoning and 82.9% for kiln seasoning; whereas, the final mean moisture content for air and kiln seasoning stacks were 16.9% and 12.4 %, respectively. during air seasoning, the mean initial mc slightly varies along the height of lumber. the bottom part of p. caribaea tree had 79.4% mc, middle part had 77.7% mc, while top part had 77.6% which is almost similar with the middle part (figure 3). the trend of mc along the height of the tree varies irregularly. figure 3: pinus caribaea lumber initial (green) (imc) and final seasoned mc (fmc) (%) 3.3 shrinkage characteristic when seasoning the p. caribaea lumber from green to 12% mc, the obtained mean mini intial and final mc for air drying mini intial and final mc for kilin drying mini intial mc along the hight of the tree 0 10 20 30 40 50 60 70 80 90 moisture content of wood m o is tu re c o n te n t (% ) initial final bottom middle top kaba et al. /journal of tropical forestry and environment vol 12, no. 01 (2022) 10-21 16 percentage values of shrinkage were tangential 4% (small), radial 1.9% (very small) and volumetric 5.4% (small); whereas, seasoning the lumber from green to 0% mc, the tangential, radial and volumetric shrinkage values of 6%, 3.2% and 9%, were obtained, respectively (table 3). the shrinkage values of seasoned wood at 12% mc vary from 4.7-12.7% for tangential shrinkage and 2.1-7.9% for radial shrinkage. tangential shrinkage is generally 1.5 to 2 times greater than radial shrinkage. the ratio of total tangential shrinkage to total radial shrinkage (t/r) was used as an index of dimensional stability. the ratio of tangential to radial shrinkage was 1.9% which was higher than 1.5 (table 3). ratios higher than 1.5 considered pronounced (acosta et al., 2008). this pronounced differential shrinkage is likely to cause wide splits, checks and distortions if the necessary precautions are not taken to seasoning of p. caribaea lumber species. figure 4: shrinkage characteristics values (%) at 12% mc reduction 3.4 density characteristics the mean density of p. caribaea lumber species at green (initial), basic, oven dry conditions and when seasoned to 12% mc were 690, 383, 350 and 660 kg/m3, respectively (table 4). based on the density value (660 kg/m3) at 12% mc, the lumber species can be classified under heavy density (650-800 kg/m3) category. according to oteng-amoako and brink (2008), wood properties show large differences between sites and between trees. the wood is moderately light weight to fairly heavy, with a density of 350-820 kg/m³ at 12% moisture content. the wood from slower-growing trees from natural stands has a higher density and lower resin content than the wood from faster-growing trees from plantations (otengamoako and brink, 2008; orwa et al., 2009). for the same species, similar value of density was observed in the rage of 450 – 650 kg/m3 (udoakpan, 2013). 3.5 air and kiln seasoning rate of p. caribaea lumbers the time required for air seasoning of p. caribaea sawn boards that have 3 cm thickness to reach to about 17% mc was 61 days, while kiln seasoning using the kiln that operates at a temperature range of 40-70ºc took 4.3 days to reach 12.4% moisture content. kiln seasoning rate was 0.62%/day. thus, the kiln seasoning was 14 times faster than the air seasoning. the species was classified as very rapid in air and kiln seasoning. the kiln seasoning significantly shortens the seasoning time required to season the lumber to ~ 12% mc (getachew d et al., 2015) lumber directions/surfaces tangential radial longitudinal volumetric kaba et al. /journal of tropical forestry and environment vol 12, no. 01 (2022) 10-21 17 table 2: summary of anova on moisture content, densities and shrinkages of p. caribaea lumber source of variation df mean square and statistical significances shrinkage from green to 12% mc (%) imc gd bd od density 12% mc tangentia l radial volume tric position2 3850.18 * 0.043* 0.004 ns 0.004 ns 0.006 ns 1.16 ns 0.132ns 1.925 ns note: ns-not significant at p<0.05, *-significant at p<0.05. where: dfdegree of freedom, imc-initial moisture content, gd-green density, bd-basic density, odoven dry density the initial moisture content (green) (imc) and green density (gd) along height of the tree were significant (p<0.05) at 95% probability level, while density (basic and at 12% mc), tangential, radial and volumetric at 12% mc were nonsignificant (table 2). table 3: summary of anova on seasoning characteristics of p. caribaea lumber source of variation df mean square and statistical significances seasoning rate %/ (hour) final mc (%) initial mc (%) seasoning rate %/hour position 2 229051.56* 60.436* 37.228ns 0.006ns seasoning method 1 4412437.770** 122.899** 132.963ns 3.713** note: ns-not significant at p < 0.05, *-significant at p < 0.05, highly significant at p < 0.01. where: dfdegree of freedom, mcmoisture content seasoning rate (%/hour) and final mc (%) along height of the tree and seasoning methods were significant (p < 0.05) at 95% probability level, while seasoning methods were significant (p < 0.01) at 99% probability level (table 3). according to oteng-amoako and brink (2008), the wood of p. caribaea exhibits good quality under air seasoning, though the end splits may occur during seasoning. boards of 3 cm thick required about 6 weeks (1.5 month) to air dry lumber from green to 16.88% moisture content. this is similar with the study carried out in fiji that around six weeks was required to dry 3 cm thick lumber from green (170% mc) to 20% mc) in open air (plumptre, 1984). to dry p. caribaea in conventional kiln up to 12% moisture content took 3-4 days; in average the kiln seasoning rate for the species was 0.62%/hour. 3.6 seasoning defects during both air and kiln seasoning methods, different defects were recorded on p. caribaea lumber. even if the degree varies, defects like warp (cup, bow, twist, and crook/spring) were seen on kiln-seasoned boards. in addition to the above defects, end splits were observed on air seasoned boards. during air seasoning crook/spring was the serious defect while on kiln seasoned boards twist was the more pronounced defect (table 4). kiln seasoning is preferred over air seasoning to produce better-quality boards at a lower cost of operation, even though some seasoning defects on seasoned boards have been observed. the dead knot which is the natural defect was the dominant type on p. caribaea lumber species. kaba et al. /journal of tropical forestry and environment vol 12, no. 01 (2022) 10-21 18 table 4: the extent of mean seasoning defects in air and kiln seasoning stacks. seasoni ng method warp (mm) checks (mm) splits dia. (mm), l. (cm) knots other defects occur cup bow tw ist cro ok surface check en d che ck end split en d spl it knots dia. (mm) no. of knots air 2 4 7 8 ----2 17 34 5 wane klin 3 2 12 3 --------30 5 wane proper stacking using standard and well-seasoned stickers, end sealants or plastic end cleats, top loading/ adjustable strapping are paramount for preventions or remedies of seasoning to minimize these defects. 3.7 comparison of p. caribaea lumber with commercial lumbers grown in ethiopia comparable lumber species with p. caribaea in terms of the rate of seasoning by kiln method (4.3 days) were eucalyptus viminalis, eucalyptus saligna and morus mesozygia (4 days), ocotea kenyensis (4.4 days) (getachew desalegn et al., 2012; getachew desalegn et al., 2015; getachew desalegn and gemechu kaba, 2017; gemechu kaba and getachew desalegn, 2020). besides, for the density at 12% mc (660 kg/m3), comparable species with p. caribaea were eucalyptus fastigata (650 kg/m3), eucalyptus obliqua (670 kg/m3), eucalyptus viminalis (670 kg/m3), morus mesozygia (670 kg/m3) (getachew desalegn et al., 2012; getachew desalegn et al., 2015; getachew desalegn and gemechu kaba, 2017; gemechu kaba and getachew desalegn, 2020). 4. conclusion and recommendations pinus caribaea has lumber and several non-lumber forest products and services. the species has comparable wood with many indigenous and home-grown exotic lumbers of ethiopia in terms of density, seasoning rate and shrinkage characteristics. different seasoning defects were observed that need care during lumber seasoning. lumber shall be seasoned using kiln seasoning method to shorten seasoning time, better maintain wood quality and suitability for different applications. in this study, the density and seasoning characteristics of pinus caribaea lumber was evaluated; and it has been observed that the moisture content (mc), seasoning time, seasoning characteristics and density of wood are amongst the main factors that can highly influence the quality, suitability and overall performance of the lumber. the main experimental factors considered in the experimentation were percentage of moisture content at green, current and final moisture content, the seasoning rate, seasoning shrinkages (i.e., in tangential, radial and volumetric directions), density of the lumber at green and air-dry conditions, and associated seasoning defects have been observed. this implies that kiln seasoning method is more effective and hence, preferable to the air seasoning of the p. caribaea lumber so as to obtain lumber products with less defects, better quality and minimum operational cost. therefore, kiln seasoning method is recommended for seasoning the lumber species in wood and forest products processing industries, and construction sectors thereby ensuring the effective, efficient and sustainable utilization of the considered p. caribaea tree. kaba et al. /journal of tropical forestry and environment vol 12, no. 01 (2022) 10-21 19 for future work, the research should be conducted regarding the presence of high resin in p. caribaea lumber and its effect on the lumber quality. the improvement of silvicultural practice is necessitated besides expanding plantation in the country (ethiopia). 5. acknowledgement the authors acknowledged the ethiopia forest development for the financial support solicited from the government of ethiopia. oromiya forestry and wildlife enterprise (head office, finfinnee branch and suba forest district) are highly appreciated for permitting the selection, harvesting, and transportation of sample trees to addis abeba for additional processing and research. the authors would also like to thank mr. dagnachew genene for reviewing the draft manuscript. finally, we would like to express our gratitude to all of the coordinating, technical and supporting staff members of the forest products innovation center for their respective participation and support during sample trees selection, harvesting, log transporting, log sawing, sample preparation, testing, saw-doctoring, and logistics supports in their respective domains. references boone, r. s. (1988). dry kiln schedules for commercial woods: temperate and tropical (vol. 57). us department of agriculture, forest service, forest products laboratory. denig, j., e.m., wengert, simpson w.t (2000). seasoning of hardwood lumber. forest products laboratory. forest service. united states. department of agriculture (usda). general technical report. pl-gtr-118. 138pp. efcc (environment, forest and climate change commission) (2020). trees, forests and profits in ethiopia: an assessment of tree-based landscape restoration investment opportunities in ethiopia. addis ababa. farmer r.h., 1987. handbook of hardwoods. department of the environment. building research establishment, princes risborough laboratory, 2nd edition, london, 243pp. fpl (forest products laboratory) (2010). wood handbook-wood as an engineering material. forest service. gen. tech. rep fpl-gtr-113. madison, wi: us, department of agriculture, 463 pp. gemechu kaba and getachew desalegn (2020). seasoning characteristics and potential uses of eucalyptus pilularis, eucalyptus viminalis and trichilia dregeana lumber tree species. wnofns 29(3) (2020) 162-178. gemechu, k., tsegaye, b., and mulugeta, l. (2018). actual and potential industrial uses of eucalyptus wood in addis ababa, ethiopia. the international journal of engineering and science 7.6, 74-79 getachew desalegn and gemechu kaba (2017). imperative physical characteristics and potential uses of eucalyptus pilularis, eucalyptus viminalis and trichilia dregeana lumber tree species. in፡ forest and environment: technologies and information, mehari alebachew, getachew desalegn, wubalem tadesse, agena anjulo and fassil kebede (eds) (june 2017). proceedings of the 1st method dissemination workshop, 26-27 november 2015. tokuma hotel, adama, ethiopia. getachew desalegn, melaku abegaz, demel teketay and alemu gezahgne (2012) . commercial timer species in ethiopia: characteristics and uses a handbook for forest industries, construction and energy sectors, foresters and other stakeholders. addis ababa university press, addis ababa. getachew desalegn, seyoum kelemwork, daniel gebeyehu (2015). forest products utilization research in ethiopia: highlights on major achievements and contributions. isbn: 978-3-659-94786-5. ethiopian environment and forest research institute, addis kaba et al. /journal of tropical forestry and environment vol 12, no. 01 (2022) 10-21 20 ababa. iso/dis 3130,1975. wood-determination of moisture content for physical and mechanical experiments. iso international standard no. 3130. switzerland. 3 pp. iso/dis 3131,1975. wood-determination of density for physical and mechanical experiments. iso international standard no.3131. switzerland. 2 pp. iso/dis 4469 (international organization for standardization/draft international standard),1975. wood-test methods-determination of radial and tangential shrinkage. iso/dis standard no. 4469. explanatory report. switzerland. 3 pp. iso/dis 4858, 1975. woodtest methods-determination of volumetric shrinkage. iso/dis standard no. 4858. explanatory report. switzerland. 4 pp. longwood f.r (1961). puerto rican woods: their machining, seasoning and related characteristics. agriculture handbook no. 205. usda forest service. us government printing office, washington, usa. loulidi i., famiri a., chergui m., elghorba m., (2012). the physical and mechanical properties of eucalyptus hybrid e. camaldulensis x e. grandis: comparison with its parental species. international journal of engineering and science vol. 1, 01-07. martín sánchez acosta, ciro mastrandrea and josé tarcisio lima (2008). wood technologies and uses of eucalyptus wood from fast grown plantations for solid products. proceedings of the 51st international convention of society of wood science and method, chile. mebrate mihertu (2004). growth performance of some indigenous and exotic tree species in south-western ethiopia. report no. 58, ethiopian agricultural research organization, addis ababa, ethiopia. mebrate mihretu (2006). species trails at belete, hanmulo, menagesha and yerer. forestry research center, addis ababa, ethiopia. mefcc (ministry of environment, forest and climate change), 2018. national forest sector development program (nfsdp), ethiopia. volume i: situation analysis. mefcc (ministry of environment, forest and climate change), 2018. standardized baseline for improved institutional cookstoves in ethiopia. moya r., urueña e., salas c., muñoz f. and espinoza o (2013). kiln seasoning behavior of lumber from ten fast-growth plantation species in costa rica. wood material science and engineering, 8:1, 37-45. nascimento, m. f., almeida, d. h., almeida, t. h., christoforo, a. l., & lahr, f. a. r. (2018). physical and mechanical properties of sabiá wood (mimosa caesalpiniaefolia bentham.). curr j appl sci techol, 25(4), 1-5. orwa c, a mutua, kindt r, jamnadass r, s anthony (2009). pinus caribaea. agroforestree database: a tree reference and selection guide version 4.0(http://www.worldagroforestry.org/sites/treedbs/treedatabases.asp). oteng-amoako, a.a. and brink, m., 2008. pinus caribaea morelet. in: louppe, d., otengamoako, a.a. & brink, m. (editors). prota 7,1: lumbers/bois d’oeuvre 1. prota, wageningen, netherlands. plumptre, r.a (1984). pinus caribaea. volume 2: wood properties. unit of tropical silviculture, commonwealth forestry institute, university of oxford. reeb j.e. and brown t.d., 2007. air-and shed-seasoning lumber. oregon state university. kaba et al. /journal of tropical forestry and environment vol 12, no. 01 (2022) 10-21 21 extension service. udoakpan, u.i ,2013. an evaluation of wood properties of pinus caribeae (morelet) in oluwa forest reserve, ondo state, nigeria. ethiopian journal of environmental studies and management vol. 6 no.2. united nations – food and agricultural organization (un-fao), 2019. forest products. yearbook. food and agriculture organiza the united nations. rome, 2019. microsoft word 1. feature article jayasingha. /journal of tropical forestry and environment vol. 6. no 02 (2016) 1-13 *correspondence: jpathmak@gmail.com tel:+94718433319 issn 2235-9370 print/issn 2235-9362 online © university of sri jayewardenepura 1 feature article social geology and landslide disaster risk reduction in sri lanka p. jayasingha* landslide research and risk management division, national building research orgnisation abstract landslide disaster risk reduction is presently a challenging task facing by sri lankan geologists. increasing trend of population growth in sri lanka has adversely affected the stability of central highland due to various human activities. among them establishment of human settlements and change in land use pattern have become a serious issue in triggering land instabilities in central highland of the country. national building research oragnisation which is the main focal point in land slide disaster risk reduction in sri lanka has taken valuable and timely needed actions including preparation of landslide hazard zonation maps, early warnings and mitigations. though the landslide is a geological phenomenon, it is highly interacted with human societies. hence managing the issues arising with the landslide occurrence should be addressed with a sociological approach. this new approach is known as socio geological approach which is discussed here. key words: landslide, geology, socio geology, social geologist 1. introduction overcoming the increasing threat and reducing the potential risk of landslide disasters are the present day challenges faced by the geologists working in the disaster management sector of sri lanka. though the landslide occurrence in the country is a natural hazard triggered by natural factors such as unusually cumulating rainfall, increasing density of vegetation cover and accumulating weight of over lying soil blanket (rathnayake and herath, 2005; dissanayake and rupasingha, 2007; blackenburg et al., 2007), recent observations have shown that the human intervention in triggering has dramatically been trending up. in reasoning the trend of human intervenes, the growth of population (figure 1) becomes the top due to result of it which has caused many changes in land use pattern of the country. utilization of lands in central highland is characterized by establishment of human settlements, construction of new roads and road widening, setting up of hydropower schemes and cultivating economic crops and vegetables. blocking out of large lands for selling in catering with the demand for human settlements is increasingly dominated. hence, diminishing of large land owners is one of the prominent issues arisen with the population growth. the well noted recent observations in the central highland of the country are the blocking out of state sector lands and promoting medium and small scale plantations that have led to degrade the hilly environment (mungai et al., 2004). and also, it is clearly evidenced that the land clearing including road cuts which triggers soil erosion and unnecessary water infiltration has initiated unstable slopes in hilly areas (herath et al., 2014). 2 hence this has caused frequent mass movements and cutting failures during the recent monsoon and extreme weather conditions (figure 2). figure 1: trend of population growth in sri lanka. figure 2: cutting failure at hakgala due to road cuts. jayasingha. /journal of tropical forestry and environment vol. 6. no 02 (2016) 1-13 3 the population of the central highland accounts for 30% of the total populations and the central highland which covers 20% of the total land area of the country is divided into 12 districts where most places are prone to landslide hazard (figure 3). hence it is obvious that increase of the population in the central highland of sri lanka which leads to new establishment of human settlements and expanding of urbanized areas and road network escalates the landslide vulnerability, hence to accelerate the risk of landslide disaster. loss of lives (figure 4), abandoning of settlements and economic grounds and destroying infrastructure facilities which are resulted by landslide disasters has led to various social and economic issues in the country (kjekstad and highland, 2009). figure 3: distribution of occurred landslides in sri lanka. 4 figure 4: number of deaths due to landslide hazard in sri lanka (2000-2016). in comparison, the social and economic issues arisen from landslide disasters have become major burning issues in the country (katupotha, 1999). it can be inferred that those social and economic issues have mainly been resulted due to lack of awareness on landslide which is one of the worst geo-hazards in sri lanka and the post disaster consequences. the lack of awareness in landslide hazard can seriously affect disaster management program. hence understanding the nature and the behavior of landslide occurrences in sri lanka should essentially be needed by both potential victims and personals of disaster management. such awareness on landslide hazard greatly influences a proper and systematic approach in different stages of landslide disaster risk reduction program such as pre-disaster stages, response and post disaster stage. hence, disseminating the knowledge on landslide geo hazard to the community in reducing the sociological stress can be considered as a part of present day challenges facing by the geologists in landslide disaster context of the country. dealing with social issues due to geological phenomenon such as landslide and tsunami or geological resources such as water, coal and petroleum is discussed in “social geology” which is a naval concept developing in the world (mataperello, 2012). social geology, the new discipline of geology, is a timely concept which can be used to address the sociological issues arisen from landslide disaster in sri lanka (jayasingha et al., 2016). this paper describes the application of social geology in landslide disaster risk reduction and the essential steps of social geology to be applied in landslide disaster risk reduction. 2. landslide disaster risk reduction in sri lanka the main focal point of landslide disaster risk reduction in sri lanka is the national building research organisation (nbro) established in 1985. considering her 30 years of contribution and experience, nbro has been accepted and authorized by the government to be the mandatory national institute for landslide disaster risk reduction in the country. nbro was authorized to regulate any kind of development activity within landslide prone districts by a government circular (nbro/2011/1). hence nbro is powered to investigate and assess each and every site specific landslide risk and issue technical recommendations in reducing landslide risk. nbro has strong connections and jointly works with disaster management centre (dmc), department of meteorology, department of irrigation and local authorities of sri lanka in landslide disaster risk reduction. jayasingha. /journal of tropical forestry and environment vol. 6. no 02 (2016) 1-13 5 the landslide disaster risk reduction program in sri lanka is a cyclic process as given in the figure 5. it consists mainly of three stages as given as (i) pre-disaster stage, (ii) response stage and (iii) post disaster stage. risk assessment, prevention/mitigation and preparedness are the main activities of pre-disaster stage. soon after a landslide disaster is occurred, response stage comes in to action in rescuing and securing mainly human life and related infrastructures. hence evacuation, rescue activities, immediate assistance for affected communities, assessment of damages and restorations of infrastructures are carried out. post disaster stage includes somewhat long term activities such as reconstruction, economic and social recovery and ongoing developments activities. in addition, again risk assessment, prevention and mitigation activities are also considered in post disaster stage. figure 5: landslide disaster risk reduction process in sri lanka. in sri lanka, preparation of hazard zonation maps, setting up of an early warning system based on automated rain gauges, establishment of low enforcements, conducting community awareness and taking structural mitigatory measures are the kind of preparedness activities of pre disaster stage presently carried out. issuing early warning considering real time rainfall data can be considered as a kind of prevention activity practiced in sri lanka. the stage of response after a landslide disaster occurred is the most crucial and complicated stage where various community involvements should strongly be needed specially in rescuing, evacuating, temporary resettling and facilitating activities. 3. geological nature of landslides in sri lanka according to the geology of sri lanka (figure 3), the central highland is composed of proterozoic high grade metamorphic rocks (cooray, 1994). all most all the landslides occurred and the potential grounds have been resulted by prolonged weathering of those rocks. most of the rocks in those metamorphic terrains are mineralogically composed of feldspar and flaky minerals such as mica and they are structurally weaken due to various 6 weak zones such as foliation, joints and fractures (figure 4). due to its locality that close to the equator, sri lanka is always experiencing the impact of tropical climate. hence the rocks of the central highland are undergoing high rate of weathering that thicken the overlying soil blanket. therefore it can be considered that the nature of geology is vital factor of triggering, though the most landslides occurred in sri lanka were hydrometeorologically induced. differential weathering of rocks specially due to geological structures in the central highland causes different geomorphologies (romer, 2007; phillips, 2005). hence steep slopes are common in the central highland (figure 5). it is obvious that the thickening of soil profiles is high in wet zone of in the central highland rather than that of in dry zone. the thick soil profiles in steep slopes tend to form landslide potential grounds in the central highland of sri lanka. considering the soil characteristics, it is important to understand the types of soils in landslides and potential grounds. there are two soil types that can be identified as residual soil resulted from weathering of metamorphic rocks (fookes, 1997) and colluvial soil (figure 6) resulted from short distance transportation of residual soil (nagarjan, 2000). the areas of landslide occurred are characterized by colluvial soil, but potential ground may consists of both. figure 6: a colluvial soil profile shows two stages of deposition of transported materials. due to the rapid growth of population most of the slope in the central highland have been touched and disturbed. poor consideration and lack of knowledge of geology, geomorphology and geological hazards, soil cuts for constructing buildings and new roads jayasingha. /journal of tropical forestry and environment vol. 6. no 02 (2016) 1-13 7 and road widening have been extensively made in the central highlands. hence some stable lands and stabilized paleo landslides have presently been activated. 4. the crucial activities to be addressed by social geology after one and half decades of landslide disaster risk reduction process established in sri lanka, it can be seen that many components of it are yet to be developed (table 1). considering the social aspects of the landslide disaster risk reduction program, the predisaster stage is critical and a systematic approach is needed to minimize those social aspects that are predictable to happen after a disaster. however more attention and caring should be needed in response stage, because highly sensitive social impacts which are sometime immediate are identified. the social issues during the post disaster stage is severely complicated due to many reasons. if the recovery process is not properly planned and implemented, affected communities are suffered for a long time and most of the phases of social life of affected people are changed. following activities carried out in sri lankan landslide disaster risk redun process can be identified as crucial activities which largely impact on sociological sphere. table 1: summary of some of the components in disaster management program which are yet to developed. stage components to be further developed nature of responsibility affected sphere predisaster identification of local hazard zones and potential landslides geological social dissemination of information on potential landslides and vulnerable areas social and geological social dissemination of information on nature and behaviour of landslides geological and social social issuing localized early warnings among localized and regional communities geological, social and administrative social establishment of low enforcements geological, administrative and legal social setting up of evacuation roots administrative, geological and social social response evacuation geological, administrative and social social rescue administrative and social social 8 establishment of temporary shelters in previously identified and selected safe locations administrative and social social facilitating during disaster time and post disaster period administrative and social social post identification of suitable locations for establishing permanent settlements geological and administrative social identification of potential hazard zones and issuing early warning have considerably been improved during the last decades in sri lanka due to landslide zonation mapping program and rainfall based regional early warning system established by nbro. the developed 1:50 000 landslide hazard zonation maps give excellent coverage on potential hazard zones in regional scale (figure 7). hence the risk or the vulnerability of landslide disaster for a given location can easily be assessed by using the information given in the landslide hazard zonation maps. developing a risk is largely depend on behaviour and activities of humans by which land use pattern is continuously changed and it is highly temporal. hence developing permanent landslide risk map for a particular area is sometime useless. developing local hazard zonation maps (1:5000) are time and resource consuming activity where mostly geological knowledge and social /community support have to be involved. extracting traditional knowledge on local geology must essentially be included in those maps which can later be useful in defining evacuation roots and finding safe grounds. the early warning system developed by nbro is entirely based on real time rain fall data gathered from automated rain gauges installed in 160 locations that covers the central highland of the country. in addition manual rain gauges (more than 2,000) have been given to the communities in previously identified vulnerable areas. alert, warning and evacuation are given by three different threshold limits set as 75mm, 100mm and 150mm of rain fall during a three days period (liyanage et al,. 2016). based on the real time data, vulnerable and risk areas for landslide are forecast. more importantly, the need of localized early warning systems have recently been identified. as presently experiencing, the local climatic pattern can be deviated from the regional pattern and hence issuing early warnings can sometime be problematic and contradicted. therefore, establishment of localized early warning systems in reduction of landslide risk at local level should essentially be developed soon and it can further be stressed that involvement of vulnerable communities must be vital. jayasingha. /journal of tropical forestry and environment vol. 6. no 02 (2016) 1-13 9 figure 7: distribution of hazard zones of the central highland sri lanka. setting up of evacuation routes in potential landslide areas is one of the critical steps which should be well planned before come to evacuation phase. hence successful evacuation is totally depend on secured and undisturbed routes. in defining of evacuation routes which are entirely site specific, resident knowledge in geology and geomorphology is needed. not only that, native information and traditional knowledge should be merged with the resident knowledge of geology, geomorphology, landslide hazard phenomenon and triggering factors. also identification and selection of safe grounds for temporary settlements is largely helped from information given by local community (figure 8). 10 figure 8: setting up of evacuation routes with the involvement of community. though decision making on identification of communities to be permanently evacuated and abandoning of public places such as schools and hospitals are mainly based on potential risk of landslide disaster and landslide hazard geology, many social geological factors including needs of community and phase changes in day today activities of affected communities must be taken into consideration. no any mitigation in high hazard zones is considered by nbro and hence permanent evacuation is recommended. but if a particular community is located in a potential or developing or partly occurred landslide area of medium hazard and low hazard zones, mitigation program is proposed considering the actual needs of community and it is implemented irrespective of cost of mitigation. hence it is well understood that social aspects are the prime concern in this regard. 5. socio geological approach in landslide disaster risk reduction any social aspects related to landslide disaster risk reduction can be discussed under discipline of “social geology”. hence all of them should be considered and addressed sociogeologically to improve the present day lacks and gaps in landslide disaster risk reduction process in sri lanka. the proposed social geological approach here points out the essential role of geologists in securing and saving the human lives who are to be affected by landslide hazards. the vital requirement of dissemination of geoscientific knowledge among different social groups including the communities at grass root levels is clearly understood and sharing the knowledge among those groups is highly encouraged in this approach. building up of “socio-geological network” is the prime concern in the proposed social geological approach. hence, among the various stake holders in landslide disaster risk reduction process, geologists and vulnerable/affected communities are considered as the main interacting parties. five main aspects of the proposed approach are also identified. they are; identification, awareness, application, action and exchange (table). networking all the stakeholders and various social groups in potential landslide areas with a central governing body of which the core is consists of geologists keeps the connectivity. the central governing body, social media, emergency services and conducting awareness are the main pillars of the socio-geological network (jaysingha et al., 2015). development of a mechanism for dissemination of real time data and information is essential and rapid dissemination will strengthen the connectivity of the stakeholders in the socio-geological network. jayasingha. /journal of tropical forestry and environment vol. 6. no 02 (2016) 1-13 11 table 2: main aspects of social geology in landslide disaster risk reduction. aspects description involvements identification identification of state and geological nature of landslide disaster and assessing potential risk. identification of potential or affected communities and gathering all site specific social geological information geologists, social geologists, engineering geologists geotechnical engineers civil engineers awareness aware communities engaged with landslide disaster specially on geology, geo hazards, hazard zonation maps, rescue, evacuation, mitigation program, early warnings etc. extracting and sharing local and traditional knowledge related to landslide disaster. aware and defining role of each parties and other stakeholders engaged with landslide disaster. social geologists, geologists, public communities administrators stakeholders action forming a socio-geological network defining all activities in landslide disaster risk reduction including development of mechanism for dissemination of real time data and information. finally defining social geological risk reduction plan social geologists, geologists, engineers public communities administrators all other stakeholders application application of social geological risk reduction plan to a particular landslide disaster (potential or occurred) two main interacting parties all other stakeholders. exchange exchanging data gathered from the field such as rainfall, movements of soil mass etc and final outcomes from the crucial analysis of field/raw data with all the stakeholders such as early warnings. two main interacting parties central governing body 12 6. conclusions landslide disaster risk reduction has become an essential part of securing human life in sri lanka today mainly due to enhanced anthropogenic activities which has created many issues related to land instability. since the landslide occurrence is a geo hazard, which creates sudden disasters and from which many social groups are affected, role of geologists in landslide disaster risk reduction is vital. social aspects related to such geo hazards are discussed under new discipline called “social geology”. the social issues arisen with landslide geo hazard is quite complicated and need of systematic approach is presently understood. the social geological approach proposed here for smooth functioning of landslide disaster risk reduction program is characterized by two main interacting parties identified as geologists and potential/affected community, a central governing body and a socio-geological network. the central governing body of which the core consists of geologist keeps the connectivity with all stake holders and other engaged parties. identification, awareness, action, application and exchange are the main steps to be followed in social geological risk reduction plan. correct establishment and proper functioning of socio-geological network will greatly influence on landslide disaster rick reduction process in sri lanka. reference blackenburg, f.v., hewawasam, t. and kubik, p.w., 2004. cosmogenic nuclide evidence for low weathering and denudation in the wet, tropical highlands of sri lanka. journal of geophysical research; earth surface. 109 (f3). cooray, p.g., 1994. the precambrian of sri lanka: a historical review. precambrian research 66, 3–18. dissanayake, c.b. and rupasingha, m., 1996. environmental impact of mining, erosion and sedimentation in sri lanka. international journal of environmental studies. 51(1). fookes, p.g., 1997. tropical residual soil. a geological society engineering group working party revised report. the geological society, london. herath, m.j.m.k., kodagoda, s.s.i. and dias, a.a.v., 2014. shallow modes of slope failure in road earth cuttings in sri lanka. landslide science for a safer geoenvironment. pp 51-58. jayasingha, p., bandara, k.n., bandara, r.m.s. and jayathissa, g., 2016. social aspects in landslide disaster risk reduction in sri lanka. proceedings of the 32nd technical sessions of geological society of sri lanka published online 26th february 2016. pp25. katupotha, j., 1999. effect of landslide on society and economy in sri lanka. 2nd international conference on landslides, slop stability and the safety of infrastructures.27-28th july, 1999. kjekstad, o. and highland, l., 2009. economic and social impacts of landslides. landslides – disaster risk reduction. pp 573-587. liaynage, u.l.n.i., bandara, r.m.s., indrathilake, h.m.l. and iwasaki, i., 2016. threshold limits on slope disaster events in may, 2016. case study from kegalle district in sri lanka. nbro international symposium 2016. pp 164-168. mata-perello, j.m., mata-lleonart, r., vintro-sanchez, c. and restrepo-martinez, c., 2012. social geology; a new perspective in geology. dyna. 79(171) pp. 158-16. jayasingha. /journal of tropical forestry and environment vol. 6. no 02 (2016) 1-13 13 mungai, d.n., ongb, c.k., kitemec, b., elkaduwad, w. and sakthivadiveld, r. 2004. lessons from two long-term hydrological studies in kenya and sri lanka. agriculture, ecosystems & environment. 104(1), pp 135–143. nagarajan, r., roy, a., vinod kumar, r., mukherjee, a. and khire, m.v., 2000. landslide hazard susceptibility mapping based on terrain and climatic factors for tropical monsoon regions. bull eng geol env 58: 275. philips, j. d., 2005. weathering instability and landscape evolution. geomorphology. 67 (1– 2) pp 255–272. rathnayake, u. and herath, s., 2005. changing rainfall and its impact on landslides in sri lanka. journal of mountain science. 2(3), pp 218–224. romer, w., 2007. differential weathering and erosion in an inselberg landscape in southern zimbabwe: a morphometric study and some notes on factors influencing the longterm development of inselbergs. geomorphology. 86 (3–4) pp 349–368. chapter 7 71 estimation of recreational value of horton plains national park in sri lanka: a decision making strategy for natural resources management r. m. w. rathnayake*1 and u. a. d. p. gunawardena2 1department of tourism management, sabaragamuwa university of sri lanka, sri lanka 2department of forestry and environmental sciences, university of sri jayewardenepura, sri lanka date received: 06-08-2011 date accepted: 04-10-2011 abstract horton plains national park (hpnp) is an area of high biodiversity and exceptional endemism receiving high visitation (166,613 visitors in 2009), both by local and foreigners. although, tourism causes negative impacts on the environment, environmental valuation could be used for taking decisions on natural resources management. the study shows that the recreational value of hpnp is rs. 51.68 million rupees per year, but the total economic value could be many times higher than this. calculations showed the maximum revenue from the park could be obtained if the entrance fee is raised to rs. 472.00. this may however reduce the present visitor number by 65%, but it will improve the total revenue of the park by 314 %. these differences strengthen the common argument by both officials and the public regarding insufficient allocation of man power and funds for natural resources management. key words: wildlife, recreational value, travel cost method * correspondence: email: warath1@gmail.com tel:+94 7144 47767, fax:+94 452 280296 issn 2235-9370 print/ issn 2235-9362 online ©2011 university of sri jayewardenepura journal of tropical forestry and environment vol. 01, no. 01 (2011) 71-86 72 1. introduction official records state that the about 14 per cent of the land area is protected by the department of wildlife conservation in sri lanka, one of the highest proportions in asia (dwc, 2001: fsmp, 1995). in sri lanka, national parks are the only protected areas, which permit recreation. the national parks get more than half a million visitors a year, about 20% of who are foreigners. presently, tourism is the fourth revenue earning industry in sri lanka (cbsl, 2009). eonomics of outdoor recreation deals with the supply of and demand for natural resources for recreational purposes (mcconnell 1985). some methods were developed for estimating the economic value of nonmarket environmental goods such as parks and recreation areas in the last 50 years. these methods may be divided into two groups: revealed preference and stated preference methods. it is recorded that after the civil war in sri lanka, visitation to the national parks has drastically increased. for example in 2010, the national parks of sri lanka received 756,783 visitors including foreign visitors, and earned rs. 412.5 millions. the increasing visitation to the national park system is making it more difficult for the national park service to fulfill its dual mission of providing high quality recreational experience for the public while conserving resources for future generations. concern over rising visitation in parks, and accompanying impacts on resources and on visitor experience, has led the national park service to focus increasing attention on the concept of carrying capacity. due to market failures and imperfections, the entrance fees of the parks do not reflect the true value of the resource. such under valuation could lead to their over use and rapid degradation (hufschmidt et al., 1983) and economists show growing interest on valuation of environmental amenities. the process of valuation provides protected area managers with information about the protected area’s goods and services, the values which people (potential supporters or customers) place on those, which values are being captured and which are not, and which groups could derive more benefits through alternative uses of the protected area and are therefore inclined to be a ‘threat’ to the protected area. in this way, valuation provides useful information for management and financing decisions regarding protected areas, especially such estimated values could be used to decide appropriate user/entrance fee and recreational value which could be used to guide investment on parks. the paucity of environmental valuation information on sri lankan protected areas is still a serious drawback for proper management and conservation. inadequate funds to maintain a national park is one of the major problems faced by the wildlife authorities. a greater part of the services of a national park is felt in the category of ‘externalities’ hence it is not accurately valued and appropriated by the market mechanism. thus planners, guided by market values, tend to misallocate financial and other resources for the management of protected areas, resulting in mismanagement of the resource (rathnayake & gunewardena, 2009). the travel cost method (tcm) is the most common revealed preference method used to estimate the recreational use value of natural areas. this method was initially suggested by harold hotelling in the 1930s as a potential means of valuing national parks. clawson and knetsch developed hotelling’s approach and used the name travel cost method (tisdell, 1991). the travel cost method is applied in two different ways, namely the individual travel cost method (itcm) and the zonal travel cost method (ztcm). rathnayaka & gunawardena /journal of tropical forestry and environment vol. 01, no. 01 (2011) 71-86 73 the tcm is selected in the present study for two main reasons: 1. the site is primarily valuable to people as a recreational site. the existing endangered species and other highly unique qualities that would make values for the site significant. 2. the expenditure for carrying out a travel cost study is relatively low the objective of this study is therefore to estimate the recreational value (which is part of the total economic value) of the hpnp to facilitate national decision making during resource allocation and nature tourism promotion in hpnp. in addition, this study aims to estimate appropriate user fee which gives the maximum revenue for hpnp. 2. literature review several studies have been done in sri lanka to estimate the recreational value of national parks. de silva and kotagama (1997) estimated the consumer surplus of uadawalawe national park as rs. 2.18 millions. rathnayake and gunewardene (2002; 2009) could estimate the recreational value of three national parks in sri lanka. rs. 2.38 millions for wasgmauwa national park, and rs. 1.92 millions for kawdulla national park. sooriyabandara (2002) estimated the recreational value of minneriya national park as rs. 3.9 million. compared to other studies, the recreational value of yala national park was rs.54.4 millions (marasinghe, 2002). guntilake & vieth (1998) estimated the recreational value of pinnawela elephant orphanage which is a zoological garden, and that was rs. 12.2 millions. in addition to these studies, the recreational value of some of botanic gardens also have been estimated. abeygunawardena and kodithuwakku (1992) applied travel cost method for recreational valuation of peradeniya botanic garden. further, rathnayake & kariyawasam (2002) estimated the recreational value of peradeniya botanic garden as rs. 240 millions, and according to jayaratne and gunawardena (2004), that value is rs. 221 millions for hakgala botanic garden. the zonal travel cost method was employed by piydasa & thiruchelvam (2005) for bopath ella, and the estimated total recreation value was rs. 120 million per year. using discount rates of 8% and 6%, the present values of total consumer surplus were rs. 1820 million and rs. 2000 million per year, respectively. it is found that the recreational value of urban areas such as diywanna oya (parliament ground) is many times higher than the protected areas. that value was rs. 3890 millions (marawila and thibbotuwawa, 2010). 3. methodology 3.1 study area horton plains national park (hpnp) is located approximately between the latitudes 6047’ to 60 50" n and longitudes 800 46’ and 800 50’ e (dwc 1997). the horton plains national park (hpnp) is situated in the south of nuwara eliya district and forms a plateau in the southeastern corner of the main ridge of sri lanka’s central mountain massif. the hpnp forms the highest tableland in sri lanka, with altitude ranging from 2100 m to 2300 m. the mountain peaks of kirigalpotta (2389 m) and totupolakanda (2357 m), the second and third highest mountains in the island, arise from these plains. the horton plains received its name in hounour of sri wilmot horton, a former british covernor of ceylon. the journal of tropical forestry and environment vol. 01, no. 01 (2011) 71-86 74 3162 ha area, that forms the national park now, was first established as a nature reserve in 1969 and then re-designated as a national park in 1988. hpnp is an area of high biodiversity and exceptional endemism. therefore, hpnp is richer in endemic fauna and flora compared to other protected areas in sri lanka. hpnp is unique among other national parks of sri lanka, where visitors are allowed walk along the nature trails in the unique scenic landscape, and the highest number of visitors are recorded in this national park (166,613 visitors in 2009). the park is located 160 km away from colombo. 3.2 method 3.2.1 theory of travel cost method (tcm) the basic method of travel cost assumes that visitors visit only a single site. the basis of the travel cost method is as follows. if an individual’s utility depends on the total time spent at the considered site, the quality of the site, bundle of other commodities, the individual visitor would maximize the following utility function, max:u(x,r,q) (1) where x = bundle of other commodities r = number of visits to the site q = quality of the site in maximization of above utility function the individual is constrained by the following commodities. m + (2) where m = exogenous income pw = wage rate tw = hours of work c = monetray cost of a trip = + (3) where t* = total discretionary time tw = hours of work t 1 =round trip travel time t 2 = time spent at site rathnayaka & gunawardena /journal of tropical forestry and environment vol. 01, no. 01 (2011) 71-86 75 assumptions: 1. r and q are compliments in the utility function 2. individual is fare to choose the time spent at work and work does not convey utility or distillate directly 3. monetary cost to the site has two components, namely the entrance fee and the monetary cost of travel (cost is pd . d where pd is per kilometer cost and d is distance) substituting (3) into (2) (4) equation (4) shows that the individual income is spent totally on consuming a bundle of other commodities and a visit to the recreation site. the income has two components, exogenous income and the potential income which could be generated by allocating all the available time for work. so the utility maximization problem of the individual can be shown as; max:u(x,r,q) (f + (5) the lagrangian function of the maximization problem is: l = u (6) where f = entrance fee pd = cost per kilometer d = travel distance in kilometers the first order necessary conditions are = λ (7a) = λ (7b) m + (7c) where ë is marginal utiliy of money income. the maximization of utility equation subject to the constraint equation results in the individual’s demand function for visits journal of tropical forestry and environment vol. 01, no. 01 (2011) 71-86 76 r = r (pr(f,pd,d,pw,t1,t2),m,q) (8) the model is derived for an individual and estimating the demand function requires time series data on the number of visits of each visitor. since it is difficult to collect such a data set, an alternative method is used instead. the country is divided into regions and the visit rate from each region is calculated instead of the visit rate of the individuals. it is assumed that the visitors from one region have the same characteristics. the regional visit rate is assumed as a proxy for the quantity demanded for recreation. visitors from a shorter regional distance to the site are expected to have a higher visit rate from a greater regional distance since the travel and the time cost is lower for closer regions. the visit rate and the travel cost have a negative relation in congruence with the law of demand. the estimated demand function could be used in calculating consumer surplus, which is the value of the national park as given in equation (9). (9) where v = value of national park p 1 = lowest total price of recreation p 2 = highest total price of recreation 3.2.2 survey design and data collection & questionnaire survey the visitors to the park were first divided into two categories i.e. local and overseas visitors. the overseas visitors have been omitted from the study to avoid the extremes that would come up due to their high purchasing power and other fees charged (i.e. transportation, lodging, entrance etc.) compared to local visitors and to avoid multiple visitor issues. data for the study were collected from both primary and secondary sources. secondary data were collected (number of visitors to the hpnp) from the visitor statistics maintained by the park wardens. primary data were collected from a field questionnaire survey. visitors were interviewed on site individually. basically the questionnaire was designed to collect the information indirectly. the questionnaire consisted of 19 sub questions/sections. information on area of residence, socio economic features, their visitation rates to hpnp, willingness to see wildlife, information on round trip mileage, travel costs, opportunity cost of travel time, length of the trip, time spent at the site, other locations visited during the same trip, quality of the recreational experience and perceptions of environmental quality at the site were obtained from the questionnaire. a separate question was directed on their proposed park entrance fee. this questionnaire was pre-tested with 15 visitor groups for clarification of feasibility of data collection before the study. the questionnaire survey was administered for the randomly selected visitors from 07.00hrs to 17.00hrs during january 2007 to december 2007. the survey was conducted both in weekdays and weekends. only seventeen districts were selected as the zones because according to the results of the pretest, number of visitors was very low from other regions during the period of the study. according to the rathnayaka & gunawardena /journal of tropical forestry and environment vol. 01, no. 01 (2011) 71-86 77 questionnaire survey visitors were very rarely (less than 5%) recorded from some districts. the past data on visitor statistics also proved this. these districts approximately lie within the concentric circles of the study sites. the information on the number of visitors from above districts in 2007 was collected from the visitor statistics database of department of wild life conservation. the visitation rates per 1000 population in each district/zone were estimated using the following equation (10). visitation rate/1000/year = (10) where v i = visitors from ith zone, n = sample size, n = total number of visitors per year p i = population in ith zone 3.2.3 total travel cost (ttc) estimation total travel cost includes both travel cost and opportunity cost of time. travel cost refers to the direct expenses incurred by visitors in getting to and from the site including fare, fuel, fees and other incidentals (oecd, 1995). opportunity cost of time is the value of time spent on the journey including time spent at the site. it is assumed that the people in zone ‘0’ have zero travel distance and time. each other zone will have an increasing travel time and distance. at present the park entrance fee to hpnp is rs. 60.00, although during the study period that fee was rs.40.00, and that fee was considered in ttc. the value of time is calculated by using the following formulae (11): value of time (rs) hour = (11) where, mi = average monthly income of each zone 30 = days per month; 8 = working hours per day 3.2.4 obtaining the statistical regression this was done to test (to explain visitation rates in terms of travel costs) the relationship between visitation rates and respective travel costs through a linear regression. minitab statistical package was used for analysis. 3.2.5 construction of the demand curve if the visitation rates of the park users can be shown as a function of the ‘price’ paid, for which travel cost is a proxy, the relationship can be taken a ‘demand curve’ for wildlife viewing at hpnp. given a demand function relating visitation rates to travel cost, the final step was to ‘anchor’ the data to the actual level of visits, and generate points on the demand curve iteration. journal of tropical forestry and environment vol. 01, no. 01 (2011) 71-86 78 zonal visitation rate per thousand population with respect to travel costs were used to estimate the demand equation for wildlife viewing. the same equation was used with data on travel costs to trace out changes in demand for visits with increasing admission fees. the area under this curve is calculated assuming that the demand curve is linear between any two points. according to figure 2, consumer surplus is the area under the demand curve above price line. in absence of an entrance fee, the entire area under the demand curve was considered as the consumer’s surplus for viewing wildlife and it is equal to the total recreational value. 3.2.6 determination of price which gives the maximum revenue the actual visitor number with a higher entrance fee is the number of visitors of all studied zones with respect to each proposed total travel cost with higher entrance fee, once the actual zonal number (q) were obtained, the total revenue (tr) can be calculated by multiplying the q by respective fee (p). q is first regressed against the respective p and the appropriate regression equation was obtained. here, when p reaches zero, q will be maximized and when p is at a maximum q will be zero. the tr is plotted against q to obtain the point which gives the maximum revenue (tr max). this is shown in figure 3. a = intercept b = slope p = a-bq …………………………… (12) tr = p x q from figure 1, p = a – bq tr = (a-bq) q = aq – bq2 a b entrance fee at trmax q q tr max p x q rathnayaka & gunawardena /journal of tropical forestry and environment vol. 01, no. 01 (2011) 71-86 figure 2: demand curve for recreation figure 3: relationship between total revenue and q 79 when tr is maximum (trmax) = 12bq = 0 then, a = 2bq q = a/2b …………………………… (13) according to equation (12), q can be calculated because a and b is given in the regression equation of p and q. once q is calculated it can be substituted in the above formulae to get the appropriate price level. this is the price or the maximum revenue, which should be charged as the entrance fee. 4. results and discussion the total number visitors and the origin of the place of travel of each visitor were recorded for a period of twelve months in 2007. even though 200 visitors were interviewed, a few had to be discarded due to information errors. the remainder of the visitors was from 17 districts and their visitation rates were also calculated (table 1). according to the data collected, most of the visitors were from colombo and gampaha districts. the lowest visitation rate was recorded from the polonnaruwa district. table 1: visitation rates for hpnp population in no. oc zone 2006 respondents visitation rate (vr) anuradhapura 791000 5 4.82 ampara 627000 3 3.65 badulla 837000 13 11.84 colombo 2421000 28 8.82 galle 1040000 13 9.53 gampaha 2125000 25 8.97 hambantota 547000 3 4.18 kalutara 1102000 15 10.38 kandy 1361000 14 7.85 kegalle 797000 12 11.49 kurunegala 1511000 10 5.05 matale 471000 5 8.09 matara 804000 65.69 moneragala 420000 5 9.08 nuwara eliya 735000 14 14.53 polonnaruwa 382000 2 3.99 ratnapura 1073000 10 7.11 journal of tropical forestry and environment vol. 01, no. 01 (2011) 71-86 80 the visitor information reveled that the highest total travel cost was from the anuradhapura district, but the opportunity cost of time of colombo visitors was higher than all other districts (table 2). the lowest total cost is recorded from the district of nuwara eliya district, because it is closer to hpnp, due to the lower opportunity cost of time. table 2: time costs, travel costs and total travel costs to hpnp the travel cost function was estimated using the ordinary least square method (ols). the estimated regression function is significant and the adjusted r2 (measure for goodness of fit) is acceptable at 41.6 %. in this study, only total travel cost value was considered. the regression equation is vr = 20.3411 0.0116450 ttc (14) (s = 2.37743 r-sq = 45.3 % r-sq(adj) = 41.6 %) n = 17, se coefficient3.567 zone travel cost (rs.) time cost (rs.) ttc anuradhapura 967 415 1382 ampara 876 400 1276 badulla 486 395 881 colombo 695 493 1188 galle 618 452 1070 gampaha 620 465 1085 hambantota 663 402 1065 kalutara 583 457 1040 kandy 627 425 1052 kegalle 670 405 1075 kurunegala 721 434 1155 matale 653 420 1073 matara 524 410 934 moneragala 510 380 890 nuwara eliya 264 325 589 polonnaruwa 691 388 1079 ratnapura 815 447 1262 rathnayaka & gunawardena /journal of tropical forestry and environment vol. 01, no. 01 (2011) 71-86 81 t ab le 3 : v is it o r n u m b er s fo r ea ch i n cr ea si n g e n tr an ce f ee c al cu la te d b y u si n g f o rm u la e n o . (1 4 ) fo r h o rt o n p la in s n at io n al p ar k t t c f or e ac h in er ea si ng e nt ra nc e fe e r s. t t c * 0 4 0 6 0 1 2 0 2 0 0 2 8 0 3 6 0 4 4 0 5 2 0 6 0 0 6 9 8 0 7 6 0 8 4 0 a n u ra d h ap u ra 1 3 8 2 1 3 4 2 1 3 8 2 1 4 0 2 1 4 6 2 1 5 4 2 1 6 2 2 1 7 0 2 1 7 8 2 1 8 6 2 1 9 4 2 2 0 2 2 2 1 0 2 2 1 8 2 (3 7 3 3 ) (3 3 6 5 ) (3 1 8 0 (2 6 2 8 ) (1 8 9 1 ) (1 1 5 5 ) (4 1 8 ) (0 ) (0 ) (0 ) (0 ) (0 ) (0 ) a m pa ra 1 2 7 6 1 2 3 6 1 2 7 6 1 2 9 6 1 3 5 6 1 4 3 6 1 5 1 6 1 5 9 6 1 6 7 6 1 7 5 6 1 8 3 6 1 9 1 6 1 9 9 6 2 0 7 6 (3 7 3 3 ) (3 4 4 1 ) (3 2 9 5 ) (2 8 5 7 ) (2 2 7 3 ) (1 6 8 9 ) (1 1 0 5 ) (5 2 1 ) (0 ) (0 ) (0 ) (0 ) (0 ) b ad u ll a 8 8 1 8 4 1 8 8 1 9 0 1 9 6 1 1 0 4 1 11 2 1 1 2 0 1 1 2 8 1 1 3 6 1 1 4 4 1 1 5 2 1 1 6 0 1 1 6 8 1 (8 8 3 1 ) (8 4 4 1 ) (8 2 4 6 ) (7 6 6 2 ) (6 8 8 2 ) (6 1 0 3 ) (5 3 2 4 ) (4 5 4 4 ) (3 7 6 5 ) (2 9 8 5 ) (2 2 0 6 ) (1 4 2 7 ) (6 4 7 ) c ol om bo 11 8 8 11 4 8 11 8 8 1 2 0 8 1 2 6 8 1 3 4 8 1 4 2 8 1 5 0 8 1 5 8 8 1 6 6 8 1 7 4 8 1 8 2 8 1 9 0 8 1 9 8 8 (1 6 8 9 2 ) (1 5 7 6 5 ) (1 5 2 0 1 ) (1 3 5 1 0 (1 1 2 5 6 ) (9 0 0 1 ) (6 7 4 7 ) (4 4 9 3 ) (2 2 3 8 ) (0 ) (0 ) (0 ) (0 ) g al l 1 0 7 0 1 0 3 0 1 0 7 0 1 0 9 0 11 5 0 1 2 3 0 1 3 1 0 1 3 9 0 1 4 7 0 1 5 5 0 1 6 3 0 1 7 1 0 1 7 9 0 1 8 7 0 (8 6 8 5 ) (8 2 0 1 ) (7 9 5 8 ) (7 2 3 2 ) (6 2 6 4 ) (5 2 9 5 ) (4 3 2 7 ) (3 3 5 8 ) (2 3 9 0 ) (1 4 2 1 ) (4 5 3 ) (0 ) (0 ) g am p ah a 1 0 8 5 1 0 4 5 1 0 8 5 11 0 5 11 6 5 1 2 4 5 1 3 2 5 1 4 0 5 1 4 8 5 1 5 6 5 1 6 4 5 1 7 2 5 1 8 0 5 1 8 8 5 (1 7 3 7 4 ) (1 6 3 8 5 ) (1 5 8 9 0 ) (1 4 4 0 6 ) (1 2 4 2 7 ) (1 0 4 4 9 ) (8 4 7 0 ) 6 4 9 1 ) (4 5 1 2 ) (2 5 3 3 ) (5 5 5 ) (0 ) (0 ) h am b an to ta 1 0 6 5 1 0 2 5 1 0 6 5 1 0 8 5 11 4 5 1 2 2 5 1 3 0 5 1 3 8 5 1 4 6 5 1 5 4 5 1 6 2 5 1 7 0 5 1 7 8 5 1 8 6 5 (4 6 0 0 ) (4 3 4 5 ) (4 2 1 8 ) (3 8 3 6 ) (3 3 2 6 ) (2 8 1 7 ) (2 3 0 8 ) (1 7 9 8 ) (1 2 8 9 ) (7 7 9 ) (2 7 0 ) (0 ) (0 ) k al ut ar a 1 0 4 0 1 0 0 0 1 0 4 0 1 0 6 0 11 2 0 1 2 0 0 1 2 8 0 1 3 6 0 1 4 4 0 1 5 2 0 1 6 0 0 1 6 8 0 1 7 6 0 1 8 4 0 (9 5 8 7 ) (9 0 7 4 ) (8 8 1 8 ) (8 0 4 8 ) (7 0 2 2 ) (5 9 9 6 ) (4 9 7 0 ) (3 9 4 3 ) (2 9 1 7 ) (1 8 9 1 ) (8 6 5 ) (0 ) (0 ) k an dy 1 0 5 2 1 0 1 2 1 0 5 2 1 0 7 2 11 3 2 1 2 1 2 1 2 9 2 1 3 7 2 1 4 5 2 1 5 3 2 1 6 1 2 1 6 9 2 1 7 7 2 1 8 5 2 (1 1 6 5 1 ) (1 1 0 1 7 ) (1 0 7 0 0 ) (9 7 5 0 ) (8 4 8 2 ) (7 2 1 5 ) (5 9 4 7 ) (4 6 8 0 ) (3 4 1 3 ) (2 1 4 5 ) (8 7 8 ) (0 ) (0 ) k eg al le 1 0 7 5 1 0 3 5 1 0 7 5 1 0 9 5 11 5 5 1 2 3 5 1 3 1 5 1 3 9 5 1 4 7 5 1 5 5 5 1 6 3 5 1 7 1 5 1 7 9 5 1 8 7 5 (6 6 0 9 ) (6 2 3 8 ) (6 0 5 3 ) (5 4 9 6 ) (4 7 5 4 ) (4 0 1 2 ) (3 2 6 9 ) (2 5 2 7 ) (1 7 8 5 ) (1 0 4 3 ) ( 30 1) (0 ) (0 ) k ur un eg al a 11 5 5 11 1 5 11 5 5 11 7 5 1 2 3 5 1 3 1 5 1 3 9 5 1 4 7 5 1 5 5 5 1 6 3 5 1 7 1 5 1 7 9 5 1 8 7 5 1 9 5 5 (1 11 2 3 ) (1 0 4 2 0 ) (1 0 0 6 8 ) (9 0 1 3 ) (7 6 0 5 ) (6 1 9 8 ) (4 7 9 1 ) (3 3 8 4 ) (1 9 7 7 ) (5 7 0 ) (0 ) (0 ) (0 ) m at al e 1 0 7 3 1 0 3 3 1 0 7 3 1 0 9 3 11 5 3 1 2 3 3 1 3 1 3 1 3 9 3 1 4 7 3 1 5 5 3 1 6 3 3 1 7 1 3 1 7 9 3 1 8 7 3 (3 9 1 7 ) (3 6 9 7 ) (3 5 8 8 ) (3 2 5 9 ) (2 8 2 0 ) (2 3 8 2 ) (1 9 4 3 ) (1 5 0 5 ) (1 0 6 6 ) (6 2 7 ) (1 8 9 ) (0 ) (0 ) m at ar a 9 3 4 8 9 4 9 3 4 9 5 4 1 0 1 4 1 0 9 4 11 7 4 1 2 5 4 1 3 3 4 1 4 1 4 1 4 9 4 1 5 7 4 1 6 5 4 1 7 3 4 (7 9 8 7 ) (7 6 1 2 ) (7 4 2 5 ) (6 8 6 4 ) (6 11 5 ) (5 3 6 6 ) (4 61 8 ) (3 8 6 9 ) (3 1 2 0 ) (2 3 7 2 ) (1 6 2 3 |) (8 7 4 ) (1 2 6 ) m on er ag al a 8 9 0 8 5 0 8 9 0 9 1 0 9 7 0 1 0 5 0 11 3 0 1 2 1 0 1 2 9 0 1 3 7 0 1 4 5 0 1 5 3 0 1 6 1 0 1 6 9 0 (4 3 8 7 ) (1 4 9 2 ) (4 0 9 4 ) (3 8 0 1 ) (3 4 1 0 ) (3 0 1 8 (2 6 2 7 ) (2 2 3 6 ) (1 8 4 5 ) (1 4 5 4 ) (1 0 6 3 ) 6 7 2 ) (2 8 1 ) n uw ar a e li ya 5 8 9 5 4 9 5 8 9 6 0 9 6 6 9 7 4 9 8 2 9 9 0 9 9 8 9 1 0 6 9 11 4 9 1 2 2 9 1 3 0 9 1 3 8 9 (1 0 2 5 3 ) (9 9 11 ) (9 7 4 0 ) (9 2 2 6 ) (8 5 4 2 ) (7 8 5 7 ) (7 1 7 3 ) (6 4 8 9 ) (5 8 0 4 ) (5 1 2 0 ) (4 4 3 5 ) (3 7 5 1 ) (3 0 6 6 ) p ol on na ru w a 1 0 7 9 1 0 3 9 1 0 7 9 1 0 9 9 11 5 9 1 2 3 9 1 3 1 9 1 3 9 9 1 4 7 9 1 5 5 9 1 6 3 9 1 7 1 9 1 7 9 9 1 8 7 9 (3 1 5 0 ) (2 9 7 2 ) (2 8 8 3 ) (2 6 1 6 ) (2 2 6 1 ) (1 9 0 5 ) (1 5 4 9 ) (1 1 9 4 ) (8 3 8 ) (4 8 2 ) (1 2 6 ) (0 ) (0 ) r at n ap u ra 1 2 6 2 1 2 2 2 1 2 6 2 1 2 8 2 1 3 4 2 1 4 2 2 1 5 0 2 1 5 8 2 1 6 6 2 1 7 4 2 1 8 2 2 1 9 0 2 1 9 8 2 2 0 6 2 (6 5 6 2 ) (6 0 6 3 ) (5 8 1 3 ) (5 0 6 4 ) (4 0 6 4 ) (3 0 6 5 ) (2 0 6 6 ) (1 0 6 7 ) (6 8 ) (0 ) (0 ) (0 ) (0 ) t ot al v is it or s 1 3 9 0 7 4 1 3 11 3 8 1 2 7 1 7 0 11 5 2 6 7 9 9 3 9 5 8 3 5 2 4 6 7 6 5 3 5 2 1 0 0 3 7 0 2 7 2 3 4 2 4 1 2 9 6 4 6 7 2 4 4 1 2 0 journal of tropical forestry and environment vol. 01, no. 01 (2011) 71-86 82 figure 4: demand curve for wildlife viewing in hpnp since the regression results were satisfactory, it was used in estimating the demand function for hpnp. the demand function was estimated by estimating the number of visitors (per year) for various levels of entrance fee. at a certain level of the entrance fee, demand will be chocked off and none will visit from that region. since both these methods give identical results (dixon and hufschmidt, 1990), the latter was used in this study. table 3 shows the visits from each zone at different levels of entrance fee and the aggregate visits. the data is plotted as a graph and was used to calculate the consumer surplus (see figure 4). the graph was divided into 16 strips and the area of each strip was calculated (assuming that the demand curve is linear between any to points) and summed up (table 4). the area under the above curve was calculated. according to the analysis, local recreational value (assuming that park entrance fee is zero) of hpnp is 51.68 million rupees per year in 2007. there are about 139074 local adult visitors per year, and the site is worth about rs. 371.58 per local visit. the demand function for hpnp is, p = 944.137 0.0074699 q (s = 141.249 r-sq = 88.3 % r-sq(adj) = 87.5 %) p = 944 0.00747 q ................................................. (15) according to formulae (15), q= a/2b 0 20000 40000 60000 80000 100000 120000 140000 160000 1200 1000 800 600 400 200 0 no. of visitors (q) p ar k f ee ( p ) r s. rathnayaka & gunawardena /journal of tropical forestry and environment vol. 01, no. 01 (2011) 71-86 83 table 4: calculation of the area under the demand curve since a is 944 and b is 0.00747, q is 63186.077. substituting this into formulae no. 15 will result in p value of rs. 472.00 which is the entrance fee, which maximizes the total revenue. total revenue at this entrance fee will be rs. rs.29823792.00. the proposed optimum park entry fee will result in reduction of total number of visitors by 64.9% (85090), it will yet maximize the total revenue of the park by 314.3 % (rs. 16488272.00). generally, with increasing the entrance fee the number of visitors to the park reduces. it is argued that people who are poor or with marginal income level are not motivated to visit the hpnp with increasing the park entrance fee. objectives of tourism with interpretation are enjoyment and conservation education. conservation education is important, because it leads the visitors to conserve biodiversity. therefore increase of park entrance fee may constrain the visitor’s right of enjoyment and conservation education opportunities. in the study it is revealed that the mean monthly income of visitors is about rs 18,000.00. therefore, visitors are not at the poor level or marginal income level. district level recreational values are given in table 5, and the highest recreational values (consumer surplus values) are recorded from nuwaraeliya, gampaha and colombo. meanwhile, the lowest recreational values are recorded from anuradhapura, ampara and polonnaruwa, and these districts are relatively far away from the hpnp. although gampaha and colombo districts are far away from the hpnp, the highest recreational values are resulted from these two districts because of high visitation and visitors’ high purchasing power. computation consumer surplus (1/2x329x80) + (329x1160) 394800 (1/2x684x80) + (684x1080) 766080 (1/2x685x80) + (685x1000) 712400 (1/2x684x80) + (684x920) 656640 (1/2x1738x80) + (1738x840) 1529440 (1/2x2604x80) + (2604x760) 2083200 (1/2x6240x80) + (6240x680) 4492800 (1/2x10460x80) + (10460x600) 7112800 (1/2x13603x80) + (13603x520) 7617680 (1/2x15073x80) + (15073x440) 7235040 (1/2x15553x80) + (15553x360) 6221200 (1/2x15871x80) + (15871x280) 5078720 (1/2x15871x80) + (15871x200) 3809040 (1/2x15872x80) + (15872x120) 2539520 (1/2x15871x80) + (15871x40) 1269680 (1/2x7936x40) 158720 user value (consumer surplus)2007 rs. 51677760 journal of tropical forestry and environment vol. 01, no. 01 (2011) 71-86 84 table 5: district level recreational values recently, all the goods and services including vehicle charges and fuel prices have been increased significantly, but the park entrance fee has not been increased for four years. therefore, it could be further argued that increase of park entrance fee may not cause harmful sociological implications. however according to the questionnaire survey, the mean park entrance fee, proposed by visitors is rs. 80.00. this value is two times higher than present fee. the park entrance fee of rs. 80.00 proposed by visitors reveals that the present entrance fee has to be changed, although this may be an underestimation, since the respondents could have acted strategically in proposing a park entrance fee. the value of the present study (rs 51.68 million) is within the range of the estimated values of the national parks. compared to other national parks hpnp and yala national park records a higher values, mainly due to their higher visitations. meanwhile, the highest recreational values were recorded for urban recreational areas like diyawanna oya (parliament ground) because more visitation is found and visitors’ expensing capacity is also high. in this study students and foreigners were excluded to narrow down the scope of the study. hence, the estimated value is lower than the real value placed by the visitors as a whole on experiencing the district recreational value anuradhapura 0.79 ampara 0.92 badulla 4.05 colombo 5.04 galle 3.3 gampaha 6.32 hambantota 1.57 kalutara 3.43 kandy 4.42 kegalle 2.44 kurunegala 3.23 matale 1.46 matara 3.51 moneragala 1.95 nuwaraeliya 6.34 polonnaruwa 1.16 ratnapura 1.75 total recreational value rs. millions 51.68 rathnayaka & gunawardena /journal of tropical forestry and environment vol. 01, no. 01 (2011) 71-86 85 wilderness and wildlife viewing of hpnp. another problem of the study was that most of the visitors do not visit hpnp only, but visit it as a part of a tour, which consists to visits of many such sites. use of travel cost of such visitors in the study gives an over estimation of the real value of hpnp. travel cost method also uses existing markets, determining a person’s value of an environmental good from what they spend on travelling in terms of time, travel expenditures and entry fees. travel cost methods are particularly useful for assessing the non-commercial tourism, recreation and leisure values of a protected area. travel cost methods, however, can be problematic in that they are data intensive, they rely on restrictive assumptions about consumer behaviour (e.g. multifunctional trips), and they are highly sensitive to the statistical methods used. 5. conclusion the study shows that while the recreational value of hpnp is rs. 51.68 million per year, the total economic value could be many times higher than this. according to the records, more than 70 million is invested on the infrastructure improvement of hpnp during the study period, which is a larger investment compared to the value generated by the wildlife parks. these differences strengthen the common argument by both officials and the public regarding insufficient allocation of man power and funds for conservation of the wildlife. most of the other problems are the result of these limitations. the problem of poaching, man-made fires and gemming, which are viewed as the crucial problems by many, could be reduced to a minimum if the protected area is managed in such a manner so as to provide necessary visitor services and facilities. the present study shows that there is a potential for earning more revenue from tourism at hpnp, and also this study justifies investing more money to conserve those national assets. fund generating for such an investment will not be a problem as the visitors could bear the cost as they generate a higher utility for their money. many argue that these national heritages must be managed better, services must be provided at a subsidized rate and entrance fees to national parks should not be kept at profit maximization level. one can argue for and against this, but it is obvious that the hpnp has specific issues that need immediate attention. hence the entrance fee to the hpnp could be revised using the findings of the study. in 2009, the park fee was revised (rs. 60.00), and according the present study it could be revised again for more revenue generation while conserving the natural assets with low visitor number, because more visitation cause negative impacts on this fragile ecosystem. the ecological and the sociological carrying capacities of the visitors could also be incorporated and entrance fee could be re-calculated. further research however needed for such integrations. according to the above findings following policy decisions could be taken by the government on natural resources conservation and revenue generation. i. nature tourism improvement at hpnp ii. recalculate the entry fee for hpnp iii. more resource allocation (human/funds) for hpnp iv. policies for tourism promotion and recreational planning journal of tropical forestry and environment vol. 01, no. 01 (2011) 71-86 86 references abeygunawadena, p. and kodithuwakku, k. a. s. s. (1992). “economics of recreational value of royal botanic garden”. proceedings of 3rd regional workshop on multipurpose trees”. kandy, sri lanka. 184-1995. central bank of sri lanka (cbsl) 2009, annual report, cbsl, colombo, sri lanka department of wildlife conservation (dwc) 1997, management plan for horton plains national park, dwc, colombo, sri lanka department of wildlife conservation (dwc), 2001, fauna and flora protection ordinance (a concise introduction), colombo de silva, k.a.i.d & kotagama, h.b. 1997. an optimal fee for entrance to udawalawe national park: an assessment. tropical agricultural research. 9: 317-329. forestry sector master plan, (fsmp) 1995, ministry of environment, rajamalwatte, battramula, sri lanka hufschmidt, m.m., james, d.e., meister, a.d., bower, b.t. & dixon, j. a. 1989. environment, natural systems and development. john hopkins, baltimore, usa. jayaratne c. t. and gunawardena u. a. d. p., 2004. estimation of local recreational value of hakgala botanical garden, proceedings of ninth international forestry and environment symposium of the department of forestry and environmental science, university of sri jayewardenepura, sri lanka. kariyawasam, d. 1992. using the travel cost method for assessing recreational benefits in a biosphere reserve, the sri lanka forester. xx(3&4):11-18 marasinghe, m.s.l.r.p, 2002. an estimate of the recreational value of yala national park. the department of national planning, ministry of policy development and implementation., colombo, sri lanka marawila, t. d. & thibbotuwawa m. (2010). to develop or to conserve? the case of the diyawanna oya wetlands in sri lanka. sandee working paper no. 52-10. south asian network for development and environmental economics. kathmandu. nepal mcconnell, k. e. 1985. the economics of outdoor recreation. in: handbook of natural resources and energy economics (ed: a. v. knesee and j. l. sweeney), elsevier science b.v., amsterdam, holland, vol. 2, pp. 677–722. piyadasa, h.t.n.i & thiruchelvam s. 2005. an estimation of the recreational value of “bopath-ella” in ratnapura: a travel cost approach. tropical agricultural research 2005 vol. 17 pp. 162-172 rathnayake r m w and gunawardena u. a. d. p. 2002. estimation of recreational value of the wasgamuwa national park, paper presented at the international conference on relating the environment to regional development organised by usj/ sida/ sarec research co-operation project and ministry of environment and natural resources, colombo, sri lanka, rathnayake r m w and gunawardena u. a. d. p. 2009. estimation of recreational value of the kawdulla national park. sri lanka journal of real estate. 2009:september sooriyabandara m.g. 2002. assessment of recreational value of minneriya national park: possibilities of sharing benefits with stakeholder community, msc thesis, post graduate institute of science, university of peradeniya. tisdell, c.a. 1991. economics of environmental conservation. elsevier science publisher, amsterdam, holland, p. 359. rathnayaka & gunawardena /journal of tropical forestry and environment vol. 01, no. 01 (2011) 71-86 microsoft word 3. kaluthanthri kaluthanthri & dasanayake. /journal of tropical forestry and environment vol. 6, no 02 (2016) 25-35 *correspondence: nilanthiedas@sjp.ac.lk tel: +94718122358 issn 2235-9370 print/issn 2235-9362 online © university of sri jayewardenepura 25 assessment of genetic diversity of some finger millet (eleusine coracana (l.) gaertn. accessions using morphological markers d.v.s. kaluthanthri1* and p.n. dasanayaka1 1department of botany, university of sri jayewardenepura, nugegoda, sri lanka date received: 16-11-2016 date accepted: 22-12-2016 abstract germplasm characterization is an important link between conservation and utilization of plant genetic resources. the study was conducted to characterize randomly selected 20 finger millet germplasm accessions obtained from plant genetic resource center, gannoruwa, sri lanka using morphological markers. morphological study was carried out using randomized complete block design (rcbd) and 15 morphological markers were recorded. analysis of variance (anova) results for quantitative morphological characters revealed that all quantitative morphological characters measured differed significantly (p˂0.05) among the accessions used for the study, indicating higher levels of morphological diversity. according to the anova results, days to flowering and days to maturity show high level of predictive capability while flag leaf length and number of productive tillers show comparatively low level of predictive capability. principal component analysis indicated that morphological characters such as days to flowering, finger number and yield per plant were the important traits contributing for the overall variability implying that breeding effort on those traits can meet the targeted objective. the clustering pattern of studied finger millet accessions based on morphological markers comprised of two major clusters. both clusters comprised of indian accessions those conserved at pgrc, gannoruwa and as well as sri lankan accessions. results of the study suggest a considerable morphological variability, which could exist among the studied traits. furthermore, this study revealed that the genetic diversity existed irrespective to the geographical origin. this finding justifies the importance of germplasm characterization. keywords: finger millet, morphological markers, germplasm accessions, genetic diversity, crop improvement 1. introduction finger millet, e. coracana (l.) gaertn. is a tetraploid crop (2n=4x=36) belonging to the order poales, family poaceae, sub family chloridoideae. this crop is widely cultivated in tropical and semi tropical regions of the world including africa, india, china, japan, australia and sri lanka as well. e. coracana has a greater nutritional value. both grain and hull of finger millet have considerable nutrient content. the grain contains carbohydrate, protein, fat, fibers, iron, calcium, minerals and essential amino acids such as leucine, tryptophan, phenylalanine and methionine. the presence of methionine is very important for the people who are depending on the staple 26 foods that lack methionine such as cassava, maize and polished rice. on the other hand finger millet has considerably higher amount of calcium compared to other cereals. the hull contains protein, fiber, calcium and phosphorus. consequently, this can be considered as the major preventive agent against malnutrition. content of each component can be changed according to the crop variety. however each and every variety has its own nutritive value. finger millet has the ability to produce higher yield than other crops under multiple stresses such as drought, soil acidity and land marginality (babu and hilu, 1993; upadgyaya et al., 2006). moreover it has excellent storage qualities (dida et al., 2007) germplasm characterization is an important link between conservation and utilization of plant genetic resources in crop improvement programmes. there are more than 200 accessions of finger millet conserved at plant genetic resource center (pgrc), gannoruwa, sri lanka. understanding of genetic diversity of those conserved accessions is an important to use them in crop improvement programmes. among the multivariate techniques, principal component analysis (pca) and cluster analysis had been shown to be very useful in selecting genotypes for breeding program that meet the objective of a plant breeder (mohammadi and prasanna, 2003). pca may be used to reveal patterns and eliminate redundancy in data sets (adams, 1995). upadhyaya et al., 2007, ulaganathan and nirmalakumari; 2015, dagnachew et al., 2012 and goswami et al., 2015 have been used morphological markers for the characterization of finger millet germplasm accessions. the study was conducted to assess phenotypic diversity of randomly selected 20 finger millet germplasm accessions conserved at pgrc, gannoruwa, sri lanka. the important objective of any plant scientist is to identify an optimum number of plant traits which are sufficient to explain the maximum variability in the crop growth from sowing to harvest (ulaganathan and nirmalakumari, 2015). 2. materials and methods 2.1 plant material a total of randomly selected 20 finger millet (eleusine corocana subsp. corocana) germplasm accessions were used in this study (table 01). seeds of these 20 accessions were obtained from the seed gene bank of plant genetic resources centre (pgrc), gannoruwa, sri lanka. 2.2 morphological characterization experimental design seeds of each accession were sown in small plastic pots filled with normal soil. pots were irrigated soon after sowing and placed in the plant house for germination. twenty days old seedlings were transplanted separately in to the large plastic pots filled with mixture of soil, sand and compost (1:1:1) as each pot contained 4 plants. a total of 20 accessions were arranged in a randomized complete block design (rcbd) with 12 individuals from each accession. data collection quantitative traits were recorded at different growth stages of the crop including flowering stage, dough stage, maturity stage and post-harvest stage from all plants (table 2). traits were scored following international plant genetic resource institute (ipgri) descriptors developed for finger millet. kaluthanthri & dasanayake. /journal of tropical forestry and environment vol. 6, no 02 (2016) 25-35 27 table 1: details of the finger millet germplasm accessions used for the study. accession accession no. accession name origin of accession organization 1/ galb-ham 000190 gal bora hambanthota pgrc 2/ gpu5-ind 000928 gpu 5 india unknown 3/ pes110-ind 000927 pes 110 india unknown 4/ balak-rat 001331 bala kurakkan rathnapura pgrc 5/ gpu114-ind 000926 gpu 114 india unknown 6/ km1-ind 000964 km – 1 india rars/ak 7/ edalk-ham 000192 edal – kur hambanthota pgrc 8/ pr202-ind 000925 pr 202 india unknown 9/ balak-kan 001815 bala kurakkan kandy pgrc 10/ indae9-ind 000909 indae/9 india unknown 11/ jnr3b-ind 000962 jnr – 3b – 1008 india rars/ak 12/ kur-n.eli 000960 kurakkan nuwara eliya pgrc 13/ sel4-ind 000911 sel no 4 india unknown 14/ edalk-kur 000426 edal kurakkan kurunegala pgrc 15/ galk-kur 000418 gal kurakkan kurunegala pgrc 16/ kirimk-rat 001304 kirimora kurakkan rathnapura pgrc 17/ kalugk-kan 001828 kalu gal kurakkan kandy pgrc 18/ kur-anu 001201 kurakkan anuradhapura pgrc 19/ hr374-ind 000910 hr 374 india pgrc 20/ kalugk-mat 001233 kalu gal kurakkan matale pgrc 2.3 statistical analysis principal component analysis principal component analysis for 14 quantitative traits was performed using minitab14 software. as suggested by johnson and wichern (1988) principal components with eigen values greater than one was considered. cluster analysis hierarchical clustering of complete linkage method with squared euclidian distance was performed using minitab14 software. data of all quantitative traits were standardized to a mean of zero and a variance of one before clustering to avoid bias that arise due to differences in measurement scales. table 2: descriptors used in morphological characterization of finger millet accessions. morphological descriptors flowering stage days to flowering flag leaf length (mm) flag leaf width (mm) maturity stage number of productive tillers days to maturity culm branching 28 dough stage plant height (cm) culm thickness (mm) finger number finger length (mm) finger width (mm) post harvest stage weight of sun dried ear at maturity (g) weight of grains per ear at maturity (g) 1000 grain weight (g) grain yield per plant (g) 3. results 3.1 morphological characterization quantitative morphological data were analyzed using software minitab version 14 to derive descriptive statistics, analysis of variance and multivariate discrimination of quantitative morphological characters. there were fifteen quantitative morphological characters all together. they were days to flowering, flag leaf length, flag leaf width, plant height, culm thickness, finger number, finger length, finger width, number of productive tillers, days to maturity, weight of sun dried ear, weight of grains per ear, 1000 grain weight, yield per plant and culm branching. out of these characters culm branching was a monomorphic character. analysis of variance (anova) of quantitative morphological markers anova results for quantitative morphological characters revealed that all quantitative morphological characters measured differed significantly (p˂0.05) among the accessions used for the study, indicating higher levels of morphological diversity (table 3). according to the anova results, days to flowering (f=37.55, adj-r2=75.77%) and days to maturity (f=51.66, adj-r2=81.6%) show high level of predictive capability while flag leaf length (f=4.3, adj-r2=22.27%) and number of productive tillers (f=3.99, adj-r2=20.77%) show comparatively low level of predictive capability. table 3: results of analysis of variance with respect to twenty accessions. quantitative morphological character f value p value (observed significant value) adj-r2 value (adjusted coefficient of) days to flowering 37.55 0.00 75.77% flag leaf length 4.30 0.00 22.27% flag leaf width 6.67 0.00 32.96% plant height 7.78 0.00 37.05% culm thickness 11.83 0.00 48.45% finger number 11.55 0.00 47.91% finger length 8.19 0.00 38.51% finger width 10.67 0.00 45.73% no of productive tillers 3.99 0.00 20.77% days to maturity 51.66 0.00 81.60% weight of sun dried ear 6.08 0.00 33.71% weight of grains per ear 6.14 0.00 33.96% 1000 grain weight 7.33 0.00 38.77% yield per plant 5.73 0.00 32.09% principal component analysis (pca) principal component analysis (pca) was performed for all measured quantitative morphological characters. the first four principal components having eigen values greater than one were extracted from the mean of fourteen normalized quantitative traits of 20 finger millet accessions. a variance of 49.0%, 13.4%, 12.4% and 8.4% were extracted from the first to the fourth components respectively. more than 90% variation was extracted from the first kaluthanthri & dasanayake. /journal of tropical forestry and environment vol. 6, no 02 (2016) 25-35 29 six principal components (table 4). as shown in table 5, morphological characters such as days to flowering, finger number, weight of sun dried ear, weight of grains per ear, 1000 grain weight and yield per plant were the major contributors for the variation observed in the first principal component. the variation in the second principal component was mainly due to flag leaf length, number of productive tillers and culm thickness. likewise, flag leaf length and finger length were the major contributors to the variation in the third principal component. the variability in the fourth component was attributed mainly due to flag leaf width and culm thickness. data from first two components were used to derive pca score plot and loading plot (figure 1 and 2). the studied 20 accessions were divided into four groups (a, b, c and d) based on the first two principal components as shown in pca score plot (figure 1). similarly, the recorded traits were divided into four groups depending on the first two principal components as shown in pca loading plot (figure 2). days to flowering and days to maturity were mainly responsible for the morphological diversity existed in group b accessions (6/km1-ind, 13/sel4-ind, 14/edalk-kur, 15/galk-kur, 16/kirimk-rat, 17/kalugk-kan, 18/kur-anu and 20/kalugk-mat) and as flag leaf length, culm thickness and number of productive tillers were responsible for the morphological diversity existed in group c accessions (8/pr202-ind, 10/indae9-ind and 19/hr374-ind). table 4: principal components showing the eigen values, proportion of variation and total variation across axis. principal eigen value proportion of total variation 1 6.8567 49.0 0.490 2 1.8777 13.4 0.624 3 1.7365 12.4 0.748 4 1.1805 8.4 0.832 5 0.6177 4.4 0.876 6 0.5077 3.6 0.913 7 0.4588 3.3 0.945 8 0.3315 2.4 0.969 9 0.1675 1.2 0.981 10 0.1191 0.9 0.990 11 0.0916 0.7 0.996 12 0.0489 0.3 1.000 13 0.0051 0.0 1.000 14 0.0007 0.0 1.000 30 figure1: pca score plot for twenty finger millet germplasm accessions. table 5: principal component analysis for 14 quantitative traits in 20 finger millet accessions – nonrotated loadings. character pc1 pc2 pc3 pc4 pc5 pc6 days to flowering 0.329 0.112 -0.171 -0.177 -0.361 0.158 flag leaf length (mm) -0.054 -0.360 -0.555 -0.149 0.063 -0.154 flag leaf width (mm) -0.215 0.293 0.060 -0.532 0.038 -0.270 plant height (cm) -0.215 0.272 -0.369 -0.022 0.494 0.365 culm thickness (mm) -0.116 -0.456 0.116 -0.555 0.320 0.167 finger number -0.328 -0.065 0.172 -0.270 -0.161 0.113 finger length (mm) -0.255 0.016 0.430 0.139 0.163 0.457 finger width (mm) -0.241 0.181 -0.374 0.220 0.298 -0.182 no of productive tillers -0.035 -0.607 -0.151 0.263 -0.096 0.257 days to maturity 0.280 0.274 -0.180 -0.099 -0.041 0.593 weight of sun dried ear (g) -0.351 0.071 -0.109 -0.103 -0.371 0.082 weight of grains per ear (g) -0.359 0.064 -0.139 0.027 -0.320 0.062 1000 grain weight (g) -0.313 0.020 0.188 0.350 0.077 -0.112 yield per plant (g) -0.351 0.015 -0.184 0.038 -0.346 0.147 s ec on d co m po ne nt first component kaluthanthri & dasanayake. /journal of tropical forestry and environment vol. 6, no 02 (2016) 25-35 31 figure 2: pca loading plot for fourteen quantitative traits in finger millet accession. cluster analysis cluster analysis was performed for all multivariate data derived from quantitative morphological characters with respect to each individual. the clustering pattern of finger millet accessions based on morphological markers is depicted in the figure 3. the dendrogram constructed by morphological markers comprises two major clusters as cluster 1 and cluster 2 (figure 3). ten accessions have grouped into cluster 1 with about 40% of similarity while the rest of ten accessions have grouped into cluster 2 with about 50% of similarity. se co nd c om po ne nt first component 32 figure 3: dendrogram of twenty finger millet germplasm accessions based on squared euclidean distances. cluster 1 has two sub-clusters as sub-cluster 1a and sub cluster 1b. sub-cluster 1a comprised of five indian accessions (19/hr374-ind, 13/sel4-ind, 5/gpu114-ind, 11/jnr3b-ind and 8/pr202-ind) and two sri lankan accessions (4/balak-rat [accession from rathnapura] and 12/kur-n.eli [accession from nuwara eliya]). sub-cluster 1b has three indian accessions (3/pes110-ind, 10/indae and 2/gpu5-ind). within the sub-cluster 1a, three mini-clusters can be identified. in here, 13/sel4-ind (accession from india) and 5/gpu114-ind (accession from india) grouped into one of mini-clusters. 8/pr202-ind (accession from india) and 11/jnr3b-ind (accession from india) grouped into one minicluster and 12/kur-n.eli (accession from nuwara eliya) and 4/balak-rat (accession from rathnapura) grouped into the other mini-cluster with low level of genetic differences between each other. apart from these three mini-clusters, 19/hr374-ind (accession from india) formed a separate mini-cluster individually. within the sub cluster 1b, 10/indae9-ind (accession from india) and 2/gpu5-ind (accession from india) grouped into a mini-cluster while 3/pes110-ind (accession from india) formed a separate mini cluster individually. cluster 2 has two-sub clusters as sub-cluster 2a and sub-cluster 2b. sub-cluster 2a comprised of one indian accession (6/km1-ind) and four sri lanka accessions (16/kirimkrat [accession from rathnapura], 14/edalk-kur [accession from kurunegala], 7/edalk-ham [accession from hambanthota] and 15/galk-kur [accession from kurunegala]). sub-cluster 2b comprised of five of sri lankan accessions (20/kalugk-mat [accession from matale], 18/kur-anu [accession from anuradhapura], 17/kalugk-kan [accession from kandy], kaluthanthri & dasanayake. /journal of tropical forestry and environment vol. 6, no 02 (2016) 25-35 33 9/balak-kan [accession from kandy] and 1/galb-ham [accession from hambanthota]). within sub-cluster 2a, two mini-clusters can be identified. 16/kirimk-rat (accession from rathnapura), 14/edalk-kur (accession from kurunegala) and 7/edalk-ham (accession from hambanthota) grouped into one of mini-clusters while 15/galk-kur (accession from kurunegala) and 6/km1-ind (accession from india) grouped into another mini-cluster with low level of genetic differences with each other. within the sub-cluster 2b, 20/kalugk-mat (accession from mathale), 18/kur-anu (accession from anuradhapura), 17/kalugk-kan (accession from kandy) and 9/balak-kan (accession from kandy) grouped into a minicluster with low level of genetic differences with each other while 1/galb-ham (accession from hambanthota) formed a separate mini-cluster individually (figure 3). 4. discussion the analysis of variance showed highly significant differences among the accessions for all studied quantitative morphological characters. this revealed that the studied accessions were genetically diverse and the significant amount of variability existed in the plant material. therefore, there is an opportunity to undertake further breeding activities like hybridization program. this is supported by the substantial variations in finger millet that have been reported in previous studies by naik et al., (1994) and prasado et al., (1994). maximum positive correlation observed for most of the characters with grain yield per plant revealed that all these characters could be simultaneously improved and it also suggested that increase in any one of them would lead to improvement of yield per plant. this further reveals the fact that the yield per plant is a character which is influenced by numerous other characters. therefore knowledge about the association between yield per plant and other characters helps in improving the selection efficiency in breeding programs. the correlation between characters may exist due to several factors including both genetic and epigenetic influences. in this case, pleiotropy and genetic linkage play major roles. according to the anova results, days to flowering and days to maturity showed high level of predictive capability while flag leaf length and number of productive tillers showed comparatively low level of predictive capability. early maturing genotypes have a great advantage in cases where terminal drought is common occurrence. it also escapes high pest or disease incidence, abnormal weather conditions and field is timely vacated for sowing of next crop. days to maturity is very important from the view of harvesting of the produce since finger millet has dual advantage of grain as well as fodder (sumathi et al., 2007). satish, 2003 and sharthabu, 2005 have reported that length of the finger has direct association with grain yield of finger millet. the principal component analysis is a statistical way of identifying plant traits which have major contributions to the observed variation among the studied accessions. results of this analysis can be used in the selection of suitable accessions with particular traits for breeding purpose. principal component analysis in this study confirmed the first principal component contributed maximum number of characters towards genetic diversity and those traits could be effectively used for further breeding programs to create more variability. days to flowering, flag leaf width, plant height, culm thickness, finger number, finger length, finger width, days to maturity, weight of sun dried ear, weight of grains per ear, 1000 grain weight and yield per plant were the most important traits contributing to the overall variability observed among the accessions. characters with high variability are very important in breeding programs. according to the cluster analysis for quantitative 34 morphological traits, 20 accessions were separated into two main clusters based on squared euclidean distances and complete linkage method. out of studied accessions, individuals of 19-hr374-ind accession produced the highest number of ears per plants, but the sizes of the ears were very small in most cases. therefore, the yield per plant from such individuals was not significantly very high. however, potential environmental influence on the phenotypes makes the process of evaluation more complex and difficult because phenotypic variations occurring due to changed in environmental conditions which could be erroneously scored in the process of germplasm characterization thus one should be careful with false positives and false negatives when the environment affects specific morphotypes (ferreria, 2005). in the present study, both local and exotic accessions have been studied and studied germplasm accessions could not be differentiated into distinct groups as local and exotic depending on morphological relatedness among the accessions. therefore, it revealed that the genetic diversity does not depend on the geographical origin. germplasm accessions collected from same district showed considerable genetic distance whereas germplasm accessions collected from different districts showed considerable genetic similarity. 5. conclusion development of new varieties, collection of genetic resource and conservation of genetic resources depend on the presence of specific character or characters. evaluation and characterization of accessions with respect to such characters are important for accomplishing varietal development, genetic resource collection and conservation. in that case, results of multivariate analysis provide a way for estimating morphological diversity among accessions. those results are useful for the evaluation of potential breeding values of studied accessions. findings of this study suggest the requirement for breeders to exploit accession from distinct groupings for the development of improved varieties. there was a significant genetic variation for all quantitative morphological traits among the accessions used in this study according to the principal component analysis. furthermore, this study revealed that the genetic diversity existed irrespective to the geographical origin. this finding justifies the importance of germplasm characterization. references adams, m.w., 1995. an estimate of homogeneity in crop plants with special reference to genetic vulnerability in dry season. phseolus vulgaris. euphytica, 26: 665-679. babu, w.e. and hilu, k.w., 1993. protein, calcium, iron and amino acid content of selected wild and domesticated cultivars of finger millet. plant foods hum. nutr. 43: 97-104. dagnachew, l., kassahun, t., masresha, f. and santie, d.v., 2012. multivariate analysis for quantitative traits in finger millet (eleusine coracana subsp. coracana) population collected from eastern and south-eastern africa: detection for patterns of genetic diversity. int. j. agric. res. 7(6): 303-314. dida, m.m., srinivasachary, s., ramakrishnan, j.l., bennetzen, m.d. and devos, k.m., 2007. the genetic map of finger millet, eleusine coracana. theor. applied genet. 114:321-332. kaluthanthri & dasanayake. /journal of tropical forestry and environment vol. 6, no 02 (2016) 25-35 35 ferreira, m.e., 2005. molecular analysis of gene banks for sustainable conservation and increased use of crop genetic resources. the role of biotechnology. villa gualino, turin, italy, 5-7. goswami, a.p., prasad, b. and joshi, v.c., 2015. characterization of finger millet [eleusine coracana (l.) gaertn.] germplasm for morphological parameters under field conditions. journal of applied and natural science 7 (2) : 836 – 838. johnson, r.a. and wichern, d.w., 1988. applied multivariate statistical analysis. prenticahill: englewood chiffs, nj. mohammadi, s.a. and prasanna, b.m., 2003. analysis of genetic diversity in crop plants salient statistical tools and considerations. crop sci. 43:1235-1248. naik, b.j., shankare, b.t.g. and seetharam, a., 1994. pattern of variability in relation to domestication of finger millet in africa and india. in k.e. riley., 347-363. prasado, k.e.r., wet, d.j.m.j., reddy, g. v. and mengesha, m.h., 1994. diversity in the small millets collection at icrisat. in k.e. riley, .331-345. satish, d., 2003, studies on genetic diversity based on productive and variability for quality traits in finger millet (eleusine coracana gaertn.). m.sc. (agri.) thesis, univ. agric. sci., dharwad. sharthabu k. s., 2005, stability analysis in white ragi (e. coracana gaertn.) genotypes. m.sc. (agri) thesis, univ. agric., dharwad. sumathi, p., john jeol, a., and muralidharan, v., 2007, genetic variability in the hybrids of finger millet (e. coracana (l.) gaertn.). j. crop res., 33 (1,2 and 3): 192-194. ulaganathan, v. and nirmalakumari, a., 2015. finger millet germplasm characterization and evaluation using principal component analysis. sabrao journal of breeding and genetics. 47 (2), 79-88. upadhyaya, h.d., gowda, c.l.l., pundir, r.p.s., reddy, v.g. and singh, s., 2006. development of core subset of finger millet germpllasm using geographical origin and data on 14 quantitative traits. gen. res. crop evo. 53:679-685. upadhyaya, h. d., gowda, c. l. l., gopal reddy, v., 2007. morphological diversity in finger millet germplasm introduced from southern and eastern africa. sat e journal, j. sat agric. res., http://www.icrisat.org/journal/sorgum_millet_other_cereals3.htm accessed 2nd november, 2015. gamage et al/journal of tropical forestry and environment vol. 8, no. 01 (2018)/ 55-63 55 radioactive and non-radioactive element analysis of dorado gas discovery of sri lanka and their influence on natural environment s.s.n. gamage1*, r.m.t.s.ratnayake1, a.m.a.d.m. senadhira2, d.a. weerasinghe2, v.a. waduge3 1 department of physics, university of sri jayewardenepura, sri lanka 2 petroleum resources development secretariat, sri lanka 3 atomic energy board, sri lanka date received: 2017-12-10 date accepted: 2018-04-29 abstract naturally-occurring radionuclides deposited beneath the earth, which are referred to as "norm" and other toxicnon-radioactive elements transported to the earth surface with the oil and gas production. hence, knowledge of the prevailing background levels of these elements in the subsurface reservoir formations is valuable to all stakeholders, most notably to regulatory authorities of the country. the drill cuttings obtained within depth range 3025m to 3095m of reservoir sand section in the deep water exploratory well (clpldorado 91 h/1z) drilled in the mannar basin offshore sri lanka were subjected to high-resolution gamma-ray spectrometry and x-ray fluorescence (xrf) spectrometry. as test results revealed activity concentration of 40k varies from 0.338 bq/g to 0.514 bq/g, 210pb from 0.007 bq/g to 0.015 bq/g, 226ra from 0.012 bq/g to 0.0145 bq/g while 232th levels are between 0.030 bq/g to 0.040 bq/g. according to the xrf testing levels of significantly hazardous non-radioactive elements are considerably lower, except for the level of the barium. the pb level varies between the 48 ppm to 22 ppm. the thorium level varies between 9.6 ppm to 10.1 ppm. manganese has a range of 5,173ppm to 653ppm.the barium levels are between 118,666 ppm to 24,400 ppm. norm concentration of the tested section were on the lower side when results matched with the iaea published data on norm concentration in oil, gas and there byproducts and therefore there will be low level of norm contaminations when the dorado gas discovery proceeds to the production stage. further there is no harmful public exposure from norm by disposing these drill cuttings to environment or storing at any site location. but the disposal of the drilling mud and handling of the drilling mud should be conducted with cautious since extremely high ba levels can potentially cause health problems. keywords: norm, drill-cuttings, oil, gas, sri lanka, xrf 1. introduction 1.1 background sri lankan upstream petroleum industry is still in the early phases of exploration in which wells are drilled to discover and assess hydrocarbon and to derive fundamental strategies for future development stages. it had been started in 1960’s and during 1972-1975 first three exploration wells were drilled pesalai-1, pesalai-2 and pesalai-3 in the cauvery basin of sri lanka. later, palk bay-1 and delftin 1976 and pedro-1 and pearl -1 in 1981were drilled but there have not been any significant hydrocarbon discoveries except small discovery in pesalai-1. * correspondence: shanthagamage@sci.sjp.ac.lk issn 2235-9370 print/issn 2235-9362 online © university of sri jayewardenepura mailto:shanthagamage@sci.sjp.ac.lk daham doi: 10.31357/jtfe.v8i1.3483 56 then in 2001, 2005, 2009 and 2012 seismic surveys has been carried out to acquire vital data. (prds-sri lanka, 2017) most recently starting from 2011 four new wells dorado, dorado-north, barracuda and wallago have been drilled and discovered natural gas from dorado and barracuda wells (ratnayake et al., 2017). this study was primarily focused on obtaining the norm concentration levels of the drill cuttings from the gas reservoir sand section of the dorado gas discovery off-shore mannar basin, compare those obtained levels with the global norm levels, and correlate the results with well log data. moreover, xrf testing results was conducted to determine non-radioactive hazardous elements. the subsurface formations which are rich in hydrocarbons are also comprise naturallyoccurring radionuclides; uranium, thorium, potassium, radium and lead which are referred to as "norm" (paranhouz, 2005) plus non-radioactive materials which are toxic to natural environment. industrial processes involved in oil and gas production such as treating and refining activities direct all these elements which are trapped inside rock layers of the earth to flow to the surface and contaminate natural environment (gray, 1993, godoy, 2003), as such radionuclides along with the other minerals which are dissolved in the salty water, precipitate out and forming various wastes at the surface during the different stages of the oil and gas production. some of these norm contaminated waste associate with the production of the petroleum industry are, hard mineral scales formed inside the pipes, sludge disposed after treating water and hydrocarbons, contaminated equipment and components and produced water. iaea safety report (2003), iaea training course report (2010). since the petroleum production processes are collecting and concentrating these norm associated waste and other toxic materials, there is a prospective of exposing them to the natural environment. therefore identification of background level of norm and non-radioactive hazards materials in the subsurface hydrocarbon bearing formations will be beneficial in predicting contamination levels during the oil and gas production. the department of physics, university of sri jayewardenepura collaboratively conducted this study with the petroleum resources development secretariat and atomic energy board of sri lanka and this was the first study which has been conducted regarding the norm background levels of discovered reservoir sand sections in the drilled exploratory wells in the mannar basin offshore sri lanka. 1.2 location of the study the mannar basin is located at approximately 60o-90o north latitude by 78o-80o east longitude, and bounded from south west to north west sri lanka, south east of india and south of the cauvery basin. in terms of size, the sl side of the mannar basin approaches in an area of approximately 42,000 km2with a sediment accumulation of possibly up to 10kms in the deeper water areas of the basin. the dorado well where drill cuttings were obtained is located in m2 block of mannar basin as shown in figure 1 (prds-sri lanka, 2013). clpl-dorado-91h/1z (dorado), well was drilled in a water depth of 1354 m, which penetrated a hydrocarbon rich sandstone between the depths of 3,044-3,069 m, measured depth (md). total depth of the well was 3,288 m, md. it is the first exploration well to discover hydrocarbons in the gulf of mannar. gamage et al/journal of tropical forestry and environment vol. 8, no. 01 (2018)/ 55-63 57 2. methodology 2.1 sample selection & preparation suitable depth range was decided for the samples selection using seismic and well log data. then 15 samples each weighing about 250 g were taken from 3,025 m to 3,095 m depth range with five meter intervals. then the drill cutting samples were air-dried. after that samples were oven dried at 100o c temperature for 10 hours to get rid of all the moisture and packed into sealed polyethylene bags. 2.2 gamma ray spectroscopy the dried drill cutting samples were grinded and were sieved through a sieve of 2 mm size. then, fine powdered samples were packed and sealed in an airtight g1 geometry container for gamma spectrometry testing and labeled according to their respective depths. then they were stored for 21 days before its testing to achieve the secular equilibrium between elements. figure 1. location of the gas discoveries and other exploration wells (ratnayake et al., (2017). 58 this test was carried out at the atomic energy board of sri lanka, using a high-resolution gamma spectrometer. the gamma spectrometry system was equipped with a coaxial n-type high purity germanium (hpge) detector connected through amplifiers and multi-channel analyzer driven by a computer based operating system. the detector had a coaxial closed facing geometry with the following specifications. detector mode gx3020 with a resolution of full width at half maximum (fwhim) at 122 kev of co-57. the detector was shielded by a cylindrical lead shield, which had average thickness of 10 cm to reduce the background radiation. genie 2000 software package was used for data acquisition. hpge gamma spectrometry system was calibrated using the point sources of 137 cs, 60 co and 241am and calibration was verified using the iaea reference materials. the efficiency calibration was done by geometric composure method (lab socs, canberra) and the test method was validated by analyzing standard reference material, iaea-134 and iaea-414 (ratnayake et al., 2017). 2.3 total activity concentration total activity concentration for uranium, thorium series and for potassium was calculated using the following equation 1 (omar et al 2008) tac =40k+6x226ra+3x210pb+232th (1) 2.4 correlation with well logs test results obtained from the testing were statistically analyzed with the well log data (gamma ray log) to validate the test results. minitab software was used for the analysis. since the well logs were in different units (gapi) the two data sets were standardized. then 2k factorial design test was applied and p value was obtained. 2.5 xrf testing five samples were selected to represent the total depth covering the reservoir sand section. from each samples 2 g quantity was separated at first .then using non contamination hand grinder the samples were grinded. then it was sieved by a sieve size of 63 mm and obtained 0.5 g. after that pressed powder method was used to prepare pellets. in the process of making pellets, 0.05 g of cellulose was added to 0.15 g of drill cutting powders. cellulose was used as a bind in making of pellets in order to pellets unbroken (iaea 1983), (demir et al., 2006). 3. results and discussion 3.1 gamma ray spectroscopy results when results of the tested samples between depth the interval considered 40k has the highest activity concentration among the elements which has highest level of 0.514 bq/g and a minimum value of 0.338 bq/g. the activity concentration levels of 210pb varied from 0.007 bq/g to 0.015 bq/g, whereas 232th varied from 0.030 bq/g to 0.040 bq/g while 226ra showed an activity concentration range of 0.0145 bq/g to 0.012 bq/g. according to calculated values of total activity concentration with depth, the total activity concentration has a maximum value of 0.64 bq/g and minimum value of 0.51 bq/g within the tested depth interval and moderately consistence throughout the 3020-3095 depth interval gamage et al/journal of tropical forestry and environment vol. 8, no. 01 (2018)/ 55-63 59 table 1: table of activity concentration level with error for tested depths. table 2 consist of norm concentration levels in oil, gas and their byproducts from iaea safety report (2003), hence when compared that levels with norm levels of reservoir section it implies that the activity concentration result levels in a low range. moreover, the whole amount of the norm in the reservoir are not mobilizing to the surface therefore the levels in the productions should be in much lower levels. according to the output of the 2k factorial design which was applied to check whether there is a significant difference test results and gamma ray log, the obtained p-value is 0.941.this p value is greater than the significance level of 5% which means there are no evidence for us to reject the null hypothesis which states that test results are equal to the gamma ray log data. therefore we could conclude that there is no significance difference between the test results and gamma ray log. hence this statistical analysis validate the gamma ray spectrometry test results to a certain extent, but the number of samples tested was not sufficient to conduct advanced analysis between results and gamma ray log hence the accuracy of the analysis will not be in a higher percentage. table 2: concentration levels of norm in oil, gas and by products iaea safety report (2003). radionuclide crude oil bq/g natural gas bq/m 3 produced water bq/l hard scale bq/g sludge bq/g 238 u <0.01 — 0.0003–0.1 0.001–0.5 0.005–0.01 226 ra 0.000–0.04 — 0.002–1200 0.1–15 000 0.05–800 210 po 0–0.01 0.002–0.08 — 0.02–1.5 0.004–160 210 pb — 0.005–0.02 0.05–190 0.02–75 0.1–1300 222 rn — 5–200 000 — — — 232 th 0.000 03–0.002 — 0.0003–0.001 0.001–0.002 0.002–0.01 228 ra — — 0.3–180 0.0 –2800 0.5–50 224 ra — — 0.5–40 — — depth interval(m) average depth k-40 (bq/g) pb-210 (bq/g) ra-226 (bq/g) th-232 (bq/g) 3020-3025 3022.5 0.388±0.016 0.007±0.001 0.012±0.001 0.030±0.002 3025-3030 3027.5 0.410±0.028 0.011±0.002 0.013±0.001 0.031±0.003 3030-3035 3032.5 0.430±0.030 0.009±0.002 0.014±0.001 0.032±0.003 3035-3040 3037.5 0.401±0.028 0.015±0.002 0.013±0.001 0.031±0.003 3040-3045 3042.5 0.421±0.018 0.008±0.002 0.014±0.001 0.035±0.003 3045-3050 3047.5 0.413±0.028 0.009±0.002 0.014±0.002 0.035±0.003 3050-3055 3052.5 0.413±0.027 0.007±0.002 0.013±0.001 0.036±0.004 3055-3060 3057.5 0.420±0.028 0.0004±0.0001 0.014±0.001 0.035±0.004 3060-3065 3062.5 0.422±0.028 0.009±0.002 0.014±0.001 0.037±0.004 3065-3070 3067.5 0.406±0.029 0.009±0.002 0.014±0.001 0.036±0.004 3070-3075 3072.5 0.422±0.029 0.011±0.002 0.014±0.001 0.038±0.004 3075-3080 3077.5 0.435±0.030 0.011±0.002 0.015±0.001 0.040±0.004 3080-3085 3082.5 0.426±0.030 0.012±0.002 0.014±0.001 0.035±0.002 3085-3090 3087.5 0.514±0.036 0.009±0.002 0.012±0.001 0.031±0.003 3090-3095 3092.5 0.419±0.029 0.008±0.002 0.012±0.001 0.035±0.004 60 3.2 xrf test results according to the xrf test results levels of significantly hazardous elements are considerably in the lower range, except the level of the barium (ba). pb varies between the 48 ppm to 22.2 ppm. the thorium level varies between 9.6 ppm to 10.1 ppm. manganese has a range of 5,173.333 ppm to 653.3333 ppm. the barium levels are between 118,666.7 ppm to 24,400 ppm. element 3,090-3,095 (m) 3,075-3,080 (m) 3,060-3,065 (m) 3,045-3,050 (m) 3,030-3,035 (m) k 19,466.670 20,400.000 17,600.000 15,200.000 13,600.000 ca 190,666.700 165,333.300 148,000.000 137,333.300 137,333.300 ti 5,773.333 3,186.667 3,000.000 0.000 0.000 ba 24,400.000 106,933.300 98,133.330 112,666.700 118,666.700 v 570.667 1,973.333 1,866.667 2,826.667 3,413.333 cr 0.000 0.000 0.000 0.000 241.333 ce 0.000 0.000 2,693.333 0.000 0.000 mn 653.333 654.667 5,173.333 4,386.667 4,093.333 fe 51,866.670 53,600.000 38,666.670 31,600.000 31,466.670 co 181.333 115.733 78.000 96.933 0.000 ni 156.000 82.667 102.533 64.533 54.533 cu 50.533 73.467 326.667 314.667 254.667 zn 77.467 165.333 961.333 849.333 801.333 ga 32.267 24.800 116.667 105.600 95.333 as 41.067 0.000 0.000 0.000 0.000 pb 22.267 39.467 48.000 41.333 46.000 br 13.600 12.933 4.640 5.187 6.493 rb 68.000 67.733 43.067 36.267 35.867 sr 540.000 546.667 458.667 418.667 458.667 th 9.653 10.133 0.000 0.000 0.000 y 11.973 22.000 9.733 8.000 8.493 as clearly visible in figure 2 ca, ba, fe has considerable levels of element concentrations in tested samples. only the barium levels are considerably higher than expected international levels. this can be due to the effect of drilling mud mixed with the drill cuttings as the samples were only dried without washing. when preparing drilling mud, baso4 is added to the fluid mixture to increase the density hence this indicates that drilling mud contains very high amount of ba. table 3: element concentrations in ppm according to the depth. gamage et al/journal of tropical forestry and environment vol. 8, no. 01 (2018)/ 55-63 61 figure 2: element concentrations in ppm with depth. 4. conclusion when the gamma-ray spectrometry taken in to the consideration, the activity concentrations levels of 40k are most prominent and considerably higher than the other norm elements. 210pb, 226ra and 232th levels do not vary considerably throughout the depth range tested. further, the accuracy of the test results of gamma ray spectrometry were confirmed by the final result of the statistical comparison with gamma ray log data, as p value is higher than 5% it indicates these is no significant difference between gamma ray log and experimental radiation levels. since the tested sample is small. the results indicates the norm levels of the dorado gas reservoir sand section is low reasonably to the sedimentary rocks found around the world, hence the mobilizing amount of norm levels to the earth surface have to be lower than the levels of the reservoir which are significantly in the lower side when compared to the iaea levels, hence if appropriate production and waste disposal procedures can be implemented such as treatment of produced water before disposal or reusing in well operations, procedure for disposal of sludge and solid waste with minimum environmental impact, health and safety regulations for workers in the oil and gas fields according to the american petroleum institute and international atomic energy agency standards (environmental protection for onshore oil and gas production operations and leases, 2009), (overview of exploration and production waste volumes and waste management practices in the united states, 2000), (guidelines for commercial exploration and production waste management facilities,2001) and iaea (2010), (2003) then the amount of contaminations from norm can further be minimized. (ratnayake et al., 2017). moreover, when considering the xrf results, apart from norms the attention should be given to the other non-radioactive hazardous element concentrations as well since the long term accumulations can pose a threat in the future. as clearly visible, only ca, ba, fe has considerable levels of element concentrations in tested samples and apart from that the barium levels are 62 considerably higher than expected international levels. this can be due to the effect of drilling mud mixed with the drill cuttings as the samples were only dried without washing. when preparing drilling mud, baso4 is added to the fluid mixture to increase the density. therefore the disposal of the drilling mud and handling of the drilling mud should be conducted in a careful manner since extremely high ba levels can potentially cause health problems. accepted barium levels are varied between 15 ppm to 3,500 ppm (tox guide tm for barium, 2007). the acceptable levels can be varied around the world according to the geographical conditions and environmental sensitivity. therefore conducting the both of these testing for drill cutting samples obtained from the other remaining wells to get a generalized value range for sedimentary rocks in the mannar basin, sri lanka would be vital for the future proceedings. acknowledgement special gratitude to petroleum resources development secretariat for providing required data and financial funds to conduct the research successfully. references canadian association of petroleum producers (2000) naturally occurring radioactive material (norm) guide. canada, pp.9. demir, f., budak, g., baydaş, e. and şahin, y. (2006). standard deviations of the error effects in preparing pellet samples for wdxrf spectroscopy. nuclear instruments and methods in physics research section b: beam interactions with materials and atoms, 243(2), pp.423-428. environmental protection for onshore oil and gas production operations and leases (2009) available at: http://www.api.org/~/media/files/policy/exploration/api_rp_51r.ashx. godoy, j.m. and petinatti da cruz, r. (2003) ‘226ra and 228ra in scale and sludge samples and their correlation with the chemical composition’, journal of environmental radioactivity, 70(3), pp. 199–206. gray, p.r. (1993) ‘norm contamination in the petroleum industry’, journal of petroleum technology, 45(01), pp. 12–16. guidelines for the management of naturally occurring radioactive material (norm) in the oil & gas industry report no: 412 (2008). available at: ftp://ftp.consrv.ca.gov/pub/oil/sb4deir/docs/haz_iaogp_2008.pdf. guidelines for commercial exploration and production waste management facilities (2001) available at: http://www.api.org/~/media/files/ehs/ environmental_performance/e_p_waste_guidelines.pdf. iaea (2003) radiation protection and the management of radioactive waste in the oil and gas industry. safety report series. iaea (2010) radiation protection and the management of radioactive waste in the oil and gas industry, training course series no.40. available at: http://www-pub.iaea.org/mtcd/publications/pdf/tcs-40_web.pdf iaea (1983) sample preparation techniques in trace element analysis by x-ray emission spectroscopy, vienna: pp.112-113.available at: http://www.iaea.org/inis/collection/nclcollectionstore/_public/15/022/15022526.pdf [accessed 23 apr. 2018]. omar, m., hamzah, m.s. and wood, a.k. (2008) ‘radioactive disequilibrium and total activity concentration of norm waste’, j nucl. & rel. tech, volume 5(2), pp. 47–56. overview of exploration and production waste volumes and wastemanagement practices in the united states (2000) available at: http:// www.api.org/~/media/files/ehs/environmental_performance/icf-wastesurvey-of-eandp-wastes2000.pdf?la=en. prds-srilanka.com. (2017). prds sri lanka origins. available at: http://www.prdssrilanka.com/exploration/origins.faces prds (2013) prds sri lanka regional geology. available at: http://www.prdssrilanka.com/exploration/mannarbasin.faces;jsessionid=d7e49c8b71958661fa9a0e253ac a7%20d1c.jvm1. gamage et al/journal of tropical forestry and environment vol. 8, no. 01 (2018)/ 55-63 63 ratnayake, r. m. t. s., gamage, s. s. n., senadhira, a. m. a. d. m., weerasinghe, d. a. and waduge, v. a.(2017). norm analysis of the reservoir sand section in the dorado natural gas discovery, mannar basin offshore sri lanka. journal of the geological society of india, 89(6), pp.683-688. toxguide tm for barium. (2007). [ebook] atlanta, ga: agency for toxic substances and disease registry. available at: https://www.atsdr.cdc.gov/toxguides/toxguide-24.pdf [accessed 9 sep. 2017]. de silva and wijayathilaka /journal of tropical forestry and environment vol. 9, no. 01 (2019) 1-6 1 feature article bioacoustics of sri lankan amphibians: a review of current knowledge and conservation significance de silva s. and wijayathilaka n.* department of zoology, university of sri jayewardenepura, nugegoda, sri lanka abstract acoustic inventory of sri lankan amphibians is still in a primitive stage. so far, only 20 amphibian species are known acoustically and are about 16% of the island amphibian fauna. altogether, twelve publications provide primary acoustic characters, yet the majority of them are not quantitative. bioacoustics is a powerful tool that can use in many disciplines, including taxonomy and conservation. this work emphasises that the current knowledge on the vocalisation of sri lankan amphibians is not adequate and highlighted its applications towards conservation and planning. keywords: vocalisation, behavior, frogs, conservation planning 1. introduction acoustic communication is one of the major methods of which the organisms use to convey information to each other. anuran amphibians are well known for their vocalising behavior, and it represents a substantial portion of their behavioral repertoire. acoustic signals of amphibians are known to encoded vital information such as reproductive fitness, species, and individual identity, size, fighting ability, mood and condition (bradbury and vehrencamp, 1998; gerhard and huber, 2002). detailed bioacoustic studies of amphibians are a critical step towards understanding their complex behaviors in the context of reproductive ecology. acoustic data increasingly use in resolving taxonomic uncertainties integrating with morphological and molecular evidence (meegaskumbura et al., 2015; wijayathilaka et al., 2016). moreover, can use in many research aspects, as a model to address essential evolutionary questions include sexual selection and speciation process (kroodsma and miller, 1996), to study the impact of the anthropogenic noise on the signal use and perception (laiolo, 2010). furthermore, basic knowledge of species-specific acoustic signals is much useful in the population census, remote monitoring, and discovering new populations as a non-invasive tool. on the other hand, integrating with other data sources, bioacoustics is vital for making effective conservation assessments, planning, and management.sri lanka is a paradise for amphibians currently is home to 120 anuran species, out of which 104 are endemic to the island (amphibia web, 2019). though it is highlighted the importance of acoustic information, only a handful of studies have been done to reveal the vocal repertoire of sri lankan species. aim of this review is to collect the literature available on vocalisation of sri lankan amphibians, highlight the knowledge gap, use, and significance in conservation assessments. 2. current knowledge on the vocal repertoires of sri lankan amphibians out of the 102 extant species recorded in sri lanka, only 19 species are known acoustically, i.e. less than 18% (table 1). as per the literature survey, only 12 publications mentioned the acoustic characters (nelson, 1973; arak, 1983; manamendra-arachchi and pethiyagoda, 2001; meegaskumbura * correspondence: nayanaw@sci.sjp.ac.lk tel: +94 713284804 issn 2235-9370 print/issn 2235-9362 online ©2019 university of sri jayewardenepura doi: https://doi.org/10.31357/jtfe.v9i1.3944 https://doi.org/10.31357/jtfe.v9i1.3944 2 and manamendra-arachchi, 2005; samarasinghe, 2011; samarasinghe, 2012; wikramasinghe et al., 2012; meegaskumbura et al., 2015; wijayathilaka and meegaskumbura, 2016; wijayathilaka et al., 2016; wijayathilaka et al., 2018; batuwita et al., 2019). table 1: acoustically known anuran species in sri lanka (* endemic species, n = no. of call recorded individuals). family species remarks reference microhylidae microhyla karunaratnei* 100 calls (n=5) wijayathilaka and meegaskumbura, 2016 microhyla mihintalei* 100 calls (n=5) wijayathilaka and meegaskumbura, 2016 30 calls (n=3) wijayathilaka et al. 2016 microhyla ornata 100 calls (n=5) wijayathilaka and meegaskumbura, 2016 microhyla zeylanica* 53 calls (n=3) wijayathilaka and meegaskumbura, 2016 uperodon nagaoi* 50 calls (n=3) wijayathilaka et al. 2018 no details manamendra-arachchi and pethiyagoda, 2001 uperodon palmatus* 50 calls (n=3) wijayathilaka et al., 2018 uperodon rohani* 50 calls (n=3) wijayathilaka et al., 2018 uperodon obscurus* 50 calls (n=3) wijayathilaka et al., 2018 2 calls. reported as “ramanella obscura” nelson, 1973 uperodon taprobanicus 10 calls (n=2) reported as “kaloula pulchra” nelson, 1973 bufonidae adenomus kandianus* 30 calls (n=3) meegaskumbura et al., 2015 adenomus kelaartii* 30 calls (n=3) meegaskumbura et al., 2015 rhacophoridae polypedates ranwellai* seven calls wickramasinghe et al., 2012 pseudophilautus asankai* (n=3) meegaskumbura and manamendraarachchi, 2005 pseudophilautus conniffae* (n=5) batuwita et al., 2019 pseudophilautus hoffmanni* (n=3) meegaskumbura and manamendraarachchi., 2005 pseudophilautus leucorhinus* 29 calls (n=6) considered as extinct species. only known from the holotype arak, 1983 pseudophilautus popularis* 61 (n=15) samarasinghe, 2011 pseudophilautus rus* 77 (n=7) samarasinghe, 2012 pseudophilautus stuarti* (n=3) meegaskumbura and manamendraarachchi, 2005 pseudophilautus viridis* (n=4) meegaskumbura and manamendraarachchi, 2005 the oldest known publication which, describe the vocal characteristics of sri lankan amphibians, uperodon taprobanicus (reported as ‘kaloula pulchra’) and uperodon obscurus (reported as ‘ramanella obscura’) are in 1973 by nelson. he has analysed the calls recorded by c.m bogert. nelson has mentioned only one call type, probably the advertisement call for both species. call duration (t), dominant frequency (f) and pulse rate (r) are the three call characters has measured for uperodon taprobanicus (t=0.5-0.8 s, f=400-700 hz, r=54-70 s-1 ) and uperodon obscurus (t=0.4 s, f=2200 hz, r=60-70 s-1) respectively. de silva and wijayathilaka /journal of tropical forestry and environment vol. 9, no. 01 (2019) 1-6 3 arak in 1983, published vocal interactions, call matching and territoriality in pseudophilautus leucorhinus. he has mentioned five call types which has used in different social contexts. he only provided the call duration of each type and call rate as call characters. so his study had mainly focused on describing the calling behavior, including call matching and territoriality. on a different note, manamendra-arachchi and pethiyagoda (2005) suggested that the taxon is known only from the holotype and now extinct. further they mention that p. leucorhinus closely resembles p. folicola and p. limbus. probably, arak might have misidentified p. limbus, as p. leucorhinus. then in 2001, manamendraarachchi and pethiyagoda discovered a new microhylid, uperodon nagaoi (‘ramanella nagaoi’) from a small fragment of rain forest in southern sri lanka. they have provided the waveform and spectrogram of the advertisement call of the newfound species. the fundamental frequency and call duration have mentioned as 850 hz and 90 ms, respectively.in 2005, meegaskumbura and manamendra-arachchi integrated the call characters to delimiting the species boundaries with molecular and morphological data. in their work, they have described eight new species of the genus pseudophilautus and four species (p. viridis, p. stuarti, p. hoffmanni, p. asankai) with acoustic data related to six common call characters. after that, similar taxonomic assessments have been done integrating acoustic data of sri lankan amphibians to understand the species boundaries. calls of endemic torrent toads, adenomus kandianus and a. kelaartii has recorded and analysed by meegaskumbura et al. in 2015. the indian population of microhyla rubra, and sri lankan population was compared using integrative taxonomy including bioacoustics and identified the sri lankan population is distinct by wijayathilaka et al. in 2016 and subsequently described as a new species, m. mihintalei. then wijayathilaka and meegaskumbura (2016) has done a comparative acoustic analysis including all four species (m. mihintalei, m. ornata, m. zeylanica, m. karunaratnei) of the genus microhyla in sri lanka.in most of the recent discoveries of new amphibian species, authors try their best to provide relevant bioacoustic information together with other characters (wikramasinghe et al., 2012; wijayathilaka et al., 2016; batuwita et al., 2019). two short communications in 2011 and 2012, samarasinghe had described the call characters of pseudophilautus popularis and p. rus respectively.highlighting the use of acoustic information in new population discoveries, wijayathilaka et al. in 2018 published the vocalization of four species, uperodon obscurus, u. palmatus, u. rohani, and u. nagaoi, a clade known as ramanella (figure 1). figure 1: four uperodon species in life (a); waveform (b) and power spectrum (c) of the advertisement call. time showed 0.4 s. (adopted from wijayathilaka et al. 2018). 4 3. uses and significance in conservation given the human-induced impacts on climate and biodiversity, amphibian conservation is more challenging than ever. habitat loss, fragmentation, degradation, environmental pollution, climate change invasive species, and pathogens have identified as the major threats to the sri lankan amphibian fauna in general (meegaskumbura and manamendra-arachchi, 2012). to battle with the increasing pressure on these versatile vertebrates, conservation tools are on much demand. bioacoustics has long been identified as a non-invasive tool in conservation science (laiolo, 2010) though; it has not received much attention until recently. even though, the species conservation and taxonomy often treated as two independent activities, taxonomic confusions and lack of taxonomic skills and information over where the boundaries of species to be set, cause problems for conservationists (mace, 2004). given the fact that the good alfa taxonomy central to biology, integrating multiple characters assist significantly to make correct taxonomic decisions. bioacoustics has been identified as one good source of evidence to use in integrative taxonomy especially when morphologically cryptic species are involved (glaw et al., 2010; meegaskumbura et al., 2015; wijayathilaka et al., 2016). amphibian explorations, surveys can largely be benefitted by efficient techniques like bioacoustics; especially in finding new species as well as new populations for known species. tree hole breeding frog, uperodon nagaoi, is one good example of such discoveries (pers. com. k. manamendraarachchi). a case study using the genus uperodon in 2018, wijayathilaka et al. have discovered several new populations of two threatened species within two weeks. understanding the home range of a species is essential in conservation prioritisation. because, most of the threatened sri lankan amphibians have assessed in iucn categories based on criteria b where the distribution parameters considered mostly such as area of occupancy (aoo), extent of occurrence (eoo) and the number of locations (iucn, 2007). cumulative threat to the survival of amphibians been increasing continuously. monitoring population persistence and reproductive fitness as well as estimating amphibian density and diversity need to be carried out frequently for a given population to understand the ongoing threats. when studying rare and cryptic species, conventional methods like capture-recapture methods, individual trapping and marking are not affordable. bioacoustics is one of the best tools that can be used for the purpose effectively. further, automated recording procedures and remote monitoring techniques have been developed and used successfully (aide et al., 2013; acevedo and villanueva-rivera, 2006; ospina et al., 2013). sexual selection in reproductive behaviors in amphibians is an important drive in evolution (ryan, 1985). vocal communication plays an essential role in the reproduction of amphibians. the main function of an anuran call is to attract gravid females. once documented the vocal repertoire descriptively and quantitatively, it can use in understanding the function of each call type using playback experiments. further, it could find the specific call characters they alter to be more successful in different social contexts (arak, 1983; gerhardt, 1991; gerhardt and huber, 2002). character evolution in the vocal repertories could also be analysed in a phylogenetic framework (cocroft and ryan, 1995; ryan and wilczynski, 2008) exploiting the conspecific attraction behavior using playback cues the distributions can slightly manipulate and encourage them to colonise and establish in newly restored habitats. further fragmented amphibian populations can be connected using call broadcasts in created habitats (james et al., 2015). such playback stations can even use to attract breeders to areas with decreased predation (egg/tadpole) such as predatory fish (morgan and buttemer, 1996). also call playback can facilitate directional movement to increase the use of refuges to minimize the threat from unfavorable conditions (robinson et al., 2013). de silva and wijayathilaka /journal of tropical forestry and environment vol. 9, no. 01 (2019) 1-6 5 4. conclusion given the advantages of precisely documented, accurately analysed vocalisations, still no information on more than 82% of extant anuran species in sri lanka. this review confirms that the attention on amphibian vocalisation studies on sri lankan amphibians is insufficient. filling this knowledge gap is much needed for their future conservation planning. references acevedo, m.a. and villanueva-rivera, l.j., 2006. using automated digital recording systems as effective tools for the monitoring of birds and amphibians. wildlife society bulletin, 34:211-214. aide, t.m., corrada-bravo, c., campos-cerqueira, m., milan, c., vega, g. and alvarez, r., 2013. realtime bioacoustics monitoring and automated species identification. peer j, 1:e103. arak, a., 1983. vocal interactions, call matching and territoriality in a sri lankan treefrog, philautus leucorhinus (rhacophoridae). animal behaviour, 31:292-302. amphibiaweb, 2019. information on amphibian biology and conservation [web application]. amphibiaweb, berkeley, california. available. http://amphibiaweb.org/. accessed 25 may 2019. batuwita, s., de silva, m. and udugampala, s., 2019. description of a new species of pseudophilautus (amphibia: rhacophoridae) from southern sri lanka. journal of threatened taxa, 11:1312013131. bradbury, j.w. and vehrencamp, s.l., 1998. principles of animal communication. sinauer associates sunderland, ma. cocroft, r.b. and ryan, m.j., 1995. patterns of advertisement call evolution in toads and chorus frogs. animal behaviour, 49:283-303. gerhardt, h.c. and huber, f., 2002. acoustic communication in insects and anurans. chicago university press. gerhardt, h.c., 1991. female mate choice in treefrogs: static and dynamic acoustic criteria. animal behaviour, 42:615-635. glaw, f., koehler, j., de la riva, i., vieites, d.r. and vences, m. 2010. integrative taxonomy of malagasy treefrogs: combination of molecular genetics, bioacoustics and comparative morphology reveals twelve additional species of boophis. zootaxa, 2383:82. hoke, k.l., ryan, m.j. and wilczynski, w., 2008. candidate neural locus for sex differences in reproductive decisions. biology letters, 4:518-521. iucn standards and petitions subcommittee, 2017. guidelines for using the iucn red list categories and criteria. version 13. prepared by the standards and petitions subcommittee of the iucn species survival commission. james, m.s., stockwell, m.p., clulow, j., clulow, s. and mahony, m.j., 2015. investigating behaviour for conservation goals: conspecific call playback can be used to alter amphibian distributions within ponds. biological conservation, 192:287-293. kroodsma, d.e. and miller, e.h., 1996. ecology and evolution of acoustic communication in birds. cornell university press, ithaca, ny. laiolo, p., 2010. the emerging significance of bioacoustics in animal species conservation. biological conservation, 143:1635-1645. mace, g.m., 2004. the role of taxonomy in species conservation. philosophical transactions of the royal society of london. series b: biological sciences, 359:711-719. manamendra-arachchi, k. and pethiyagoda, r., 2001. ramanella nagaoi, a new tree-hole frog (microhylidae) from southern sri lanka. journal of south asian natural history, 5:121-133. manamendra-arachchi, k. and meegaskumbura, m., 2012. the taxonomy and conservation status of amphibians in sri lanka. the national red list 2012 of sri lanka, 88-98 pp. 6 meegaskumbura, m. and manamendra-arachchi, k., 2005. description of eight new species of shrub frogs (ranidae: rhacophorinae: philautus) from sri lanka. the raffles bulletin of zoology, 12:305-338. meegaskumbura, m., senevirathne, g., wijayathilaka, n., jayawardena, b., bandara, c., manamendraarachchi, k. and pethiyagoda, r., 2015. the sri lankan torrent toads (bufonidae: adenominae: adenomus): species boundaries assessed using multiple criteria. zootaxa, 3911:245-261. morgan, l.a. and buttemer, w.a. 1996. predation by the non-native fish gambusia holbrooki on small litoria aurea and l. dentata tadpoles. australian zoologist, 30:143-149. nelson, c.e., 1973. mating calls of the microhylinae: descriptions and phylogenetic and ecological considerations. herpetologica, 163-176. ospina, o.e., villanueva-rivera, l.j., corrada-bravo, c.j. and aide, t.m., 2013. variable response of anuran calling activity to daily precipitation and temperature: implications for climate change. ecosphere, 4:1-12. ryan, m.j. 1985. energetic efficiency of vocalisation by the frog physalaemus pustulosus. journal of experimental biology, 116:47-52. robinson, n.m., leonard, s.w.j., ritchie, e.g., bassett, m., chia, e.k., buckingham, s., gibb, h., bennett, a.f. and clarke, m.f., 2013. review: refuges for fauna in fire-prone landscapes: their ecological function and importance. journal of applied ecology, 50:1321-1329. samarasinghe, d.j. 2011., description of the complex advertisement call of pseudophilautus popularis (manamendra-arachchi and pethiyagoda, 2005) (amphibia: rhacophoridae). zootaxa, 3002:6264. samarasinghe, d., 2012. the advertisement call of kandyan shrub frog (pseudophilautus rus). taprobanica: the journal of asian biodiversity, 4:57-58. wijayathilaka, n., garg, s., senevirathne, g., karunarathna, n.u.w.a.n., biju, s.d. and meegaskumbura, m., 2016. a new species of microhyla (anura: microhylidae) from sri lanka: an integrative taxonomic approach. zootaxa, 4066:331-342. wijayathilaka, n. and meegaskumbura, m., 2016. an acoustic analysis of the genus microhyla (anura: microhylidae) of sri lanka. plos one, 11. wijayathilaka, n., senevirathne, g., bandara, c., rajapakse, s., pethiyagoda, r. and meegaskumbura, m., 2018. integrating bioacoustics, dna barcoding and niche modeling for frog conservation–the threatened balloon frogs of sri lanka. global ecology and conservation, 16. wickramasinghe, l.m., munindradasa, d.a.i. and fernando, p., 2012. a new species of polypedates tschudi (amphibia, anura, rhacophoridae) from sri lanka. zootaxa, 3498:63-80. subasinghe et al. /journal of tropical forestry and environment vol.9, no. 01 (2019) 19-26 19 determining the performance of plantation grown young santalum album l. with different host species subasinghe s.m.c.u.p.1*, millaniyage k.p.2, hettiarachchi d.s.3 1centre for forestry and environment, department of forestry and environmental science, university of sri jayewardenepura, nugegoda, sri lanka 2department of forestry and environmental science, university of sri jayewardenepura, nugegoda, sri lanka 3school of science, edith cowan university, western australia date received: 15-03-2019 date accepted: 25-05-2019 abstract sri lanka is one of the pioneer countries to adopt the green economy concept and thereby promotes the establishment of forest plantations with the trees of high value. the essential oil produced in the heartwood of santalum album, native to india, indonesia and sri lanka fetches a very high price and it has been used for perfumery, medicinal, religious and cultural purposes over centuries of years. due to the over-exploitation, s. album resource in the wild is diminishing and therefore the government implemented strict laws to protect it. although plantation establishment has been recently started, management became difficult due to lack of technical information. s. album is an obligate hemi-parasite, and obtains certain nutrients from potential host trees via root connections called haustoria. therefore identifying the most suitable host species in s. album plantation establishment is essential. in order to test the impacts of different host species, a field trial of two hosts per s. album was established and maintained for three years for this study. s. album growth under 21 combinations of six host species including legumes (acacia auriculiformis, calliandra calothyrus, gliricidia sepium, sesbenia grandiflora) and non-legumes (coffea arabica, gravellia robusta) were examined. height of s. album was measured at two week intervals. leaf nitrogen, phosphorous, potassium and magnesium of s. album grown with 21 host combinations were also analyzed at regular intervals. height of s. album was significantly different when planted with different hosts. calliandra calothyrus was found to be the best host species in increasing height of s. album. it was followed by acacia auriculiformis and sesbenia grandiflora. the nitrogen, phosphorus, potassium and magnesium contents of s. album leaves were not significant when planted with the tested host combinations. therefore the significant height growth of s. album could be caused due to the absorption of water at different levels from different host species. keywords: santalum album, obligate parasitism, host species, haustoria, nutrient uptake 1. introduction many species of the genus santalum of family santalaceae produces a highly fragrant essential oil that can be extracted from the heartwood. this oil has been used for perfumery, medicinal and cultural purposes over centuries of years (joulain, et al., 2000). the aroma of the oil and the wood is also used by people belonging to three major religions of the world, i.e., hinduism, buddhism and islam (kumar et al., 2012). the heartwood itself is also used for carvings and making incense sticks known as agarbhatti (fox, 2000). *correspondence: upuls@sjp.ac.lk telephone: +94 71 4450339 issn 2235-9370 print / issn 2235-9362 online ©2019 university of sri jayewardenepura doi: https://doi.org/10.31357/jtfe.v9i1.3946 20 although the sapwood of s. album is white or yellow and not scented, it is also used in preparing turnery items (kumar et al., 2012) and manufacturing of incense sticks, toys and souvenirs. however, the oil produced by santalum album l., native to india, indonesia and sri lanka is known to have the best quality than oils extracted from any other santalum species. therefore, s. album is regarded as one of the most valuable trees in the world (sundararaj and muthukrishnan, 2011) and it can bring promising economic prospects for the countries through properly managed plantations. s. album is a small, evergreen tree which can grow to a height of 20 m and attain a girth of over 1.5 m. it grows at a slow rate (brand et al., 2012) and the average annual growth rates of diameter and height in sri lanka are approximately about 0.3 to 1.0 cm and 0.5 to 1.0 m respectively at the young stage (subasinghe et al., 2013). the trees in natural forests of karnataka, india shows even much lesser diameter increment averaging to about 0.3 cm per year (rai, 1990). s. album is an obligate hemi-parasite, so that it is capable of obtaining certain nutrients from the host trees via root connections known as haustoria (brand et al., 2004; fox, 2000). structurally, hosts also provide protection from sun, wind and grazing. it is believed that nutrients such as calcium and iron (rao and bapat, 1995), nitrogen and phosphate (barrett, 1998), potassium and magnesium (rangaswamy et al., 1986) are supplied by the hosts to s. album. the presence of basic amino acids indicates that leguminous plants are more efficient hosts for sandalwood growth than non-leguminous plants. according to radomiljac et al. (1998) and nagaveni and vijayalakshmi (2003), the growth performances of s. album vary when planted with different leguminous species. however, there was no considerable variation in the micronutrient contents of s. album due to the presence or absence of host species (rocha et al., 2014). although s. album is capable of making haustoria with a wide variety of plant species, a comprehensive understanding of suitable host species in sri lankan context is still lacking. determination of suitable host species plays a vital role in the establishment of plantations to maximise the commercial benefits. natural sandalwood resources are diminishing in all countries irrespective of the species and therefore, strict rules were implemented over harvesting and exporting sandalwood products. however, this may have severely reduced the sandalwood product supply to the market causing rapid increase of price over a short period of time. in sri lanka, s. album has been and harvested from the wild for traditional medicine since the known history (subasinghe, 2013). before a few decades, this species had been commonly found in the drier areas of the hilly intermediate zone of sri lanka. it was also found in smaller numbers in many other areas belonging to different climatic zones throughout the country. due to the high value of heartwood and oil, this species has been illegally harvested in large scale and therefore has been listed as a protected species in sri lanka under the flora and fauna act of 1964 and again with the recent amendment of the year 2009 (fauna and flora protection amendment act no. 22, 2009). despite with all the protection efforts, illegal harvesting of s. album still continues and therefore it is becoming scarce even in the hilly intermediate zone of the country where s. album had been commonly found in the past. commercial plantation establishment can, however, be one of the most effective ways to protect the s. album resource exist in the wild. s. album plantation establishment has recently been started in sri lanka with the involvement of the private sector. however, the lack of technical knowledge at the local conditions has become a major barrier for the management of those plantations. therefore the present study was conducted with the objective of identifying the most suitable host species for the young stage of s. album grown as plantations in sri lanka. subasinghe et al. /journal of tropical forestry and environment vol.9, no. 01 (2019) 19-26 21 2. materials and methods 2.1 establishment of the host trial a field trial of two host species per s. album plant was established in may, 2011 at the location called amupitiya (6o40/51// n, 80o43/31// e) close to balangoda town of rathnapura administrative district in sri lanka in may 2011 to test the impact of different host species. climate of amupitiya lies in between wet and intermediate. average annual rainfall of this area is >1,270 mm and average temperature varies from 25° to 30° c. there are about five dry months prevail per year. elevation of the research site is 590 m above the mean sea level. soil type of balangoda area is reddish-brown latosols and the terrain is steeply dissected, hilly rolling and undulating (somasekaran, 1997). s. album seeds were collected from healthy mother trees in march 2011 and those were pooled and germinated in a nursery. once the germinated s. album seedlings produced 4-6 leaves, those were transplanted into 1730 cm polythene bags filled with top soil (1): compost (1) and sand (1). alternanthera variegata, a small plant of family amaranthaceae, has been recorded as the most commonly used host species for s. album when grown in pots at the nursery stage (annapurna et al., 2006; loung, 2008). therefore one month before transplanting of s. album seedlings, two cuttings of a. variegata were planted as seedling hosts in the polythene pots. after transplanting, those pots were kept in a 70% shade house until transported to the selected site for filed planting. based on the literature (radomiljac et al., 1998; nagaveni and vijayalakshmi, 2003) priority was given to the legumes in selection of the suitable host species for this study. following a preliminary survey conducted by the authors of this paper, six multi-purpose plant species (table 1) were selected as suitable hosts based on their high survival rate and the ability of growing in different climatic conditions. other than legumes, coffea arabica (family: rutaceae) was selected as a suitable agroforestry species and gravellia robusta (family: proteaceae) was selected due to the timber value. due to the recognised values as timber, fuel or beans, all selected species can successfully be used in agroforestry systems with a. album. seedlings of the selected host species were raised in the same nursery where s. album seedlings were raised. those host species were planted in the field six months, i.e., may 2011 before planting s. album seedlings. the early planting of the host species provided adequate time for the root growth so that young s. album plants were able to form haustoria within a short time period. table 1: host species selected for the host trial of the present study. species code family use acacia auriculiformis calliandra calothyrus coffea arabica gliricidia sepium gravellia robusta sesbenia grandiflora aa cc ca gs gr sg fabaceae fabaceae rutaceae fabaceae proteaceae fabaceae timber, firewood fodder, firewood coffee beans fodder, mulch, firewood timber, firewood food, fodder, firewood planting holes were marked for s. album seedlings at 4 m distances in the selected field. then two hosts of various combinations were planted along north-south direction at 1.2 m away from the marked hole for s. album. altogether, 21 combinations of host species were used as aaaa, aacc, aaca, aags, aagr, aasg, cccc, ccca, ccgs, ccgr, ccsg, caca, cags, cagr, casg, gsgs, gsgr, gssg, grgr, grsg, sgsg. eight replicates were used for each combination and s. album was introduced six months after planting the host combinations, i.e., december 2011. this trial was maintained for three years until december 2014. 22 2.2 measurements height of s. album plants was measured at two-week intervals for three years. s. album leaves were collected at six month intervals. total nitrogen, phosphorous, potassium and magnesium contents per 1 g of oven dried s. album leaves were analysed to examine the nutrient supply of different host spices. once the leaves of s. album were collected at six month intervals, those were air dried to remove the excess moisture and then oven dried at 72o c for 48 hours before analysis. total nitrogen content was determined using micro-kjeldhal method. potassium and magnesium levels were determined using atomic absorption spectroscopy and phosphorous content was analysed by colorimetric determination using a spectrophotometer. the difference of the height growth of s. album plants grown with different host combinations were analysed by one-way anova using minitab© 14 software. one-way anova was used to identify the differences of leaf nutrient levels determined for 1 g of oven dried leaf samples. 3. results 3.1 impacts of different host combinations on s. album height growth height of s. album planted with different host combinations indicated significant differences at α=0.05 (f=6.38; p=0.000). however, among all the host combinations tested, s. album planted with cccc indicated the best height growth. aasg, ccsg, ccgs and aacc were the other host combinations which were not significantly different with cccc. figure 1 illustrates the height growth of s. album grown with the above five host combinations for a period of three years. height of s. album planted with the rest of the host combinations were significantly lower than the combinations given in figure 1. figure 1: s. album height growth with the best non-significant host combinations (±se). among the best five host combinations, calliandra calothyrus (cc) was observed in four combinations (figure 1) proving its ability to enhance the growth of s. album. moreover, acacia auriculiformis (aa) and sesbenia grandiflora (sg) were found in two host combinations. both non legume species, i.e., coffea arabica (ca) and gravellia robusta (gr) were not included in the best host combinations. 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 0 1 2 3 h e ig h t, m age, years aaxcc aaxsg ccxcc ccxgs ccxsg subasinghe et al. /journal of tropical forestry and environment vol.9, no. 01 (2019) 19-26 23 3.2 variation of s. album leaf nutrient contents all four nutrients tested, viz, nitrogen, phosphorus, potassium and magnesium did not show significant differences at α=0.05 among the leaves of s. album grown with all 21 host combinations (fnitrogen=1.35, pnitrogen=0.172; fphosphorus=1.50, pphosphorus=0.102; fpottasium=1.28, ppottasium=0.217 and fmagnesium=0.64, pmagnesium=0.870). due to the above results, significant differences of the nutrient contents were neither observed among the host species selected from the legume family, nor between legumes and the two non-legume host species. per 1 g of oven-dried sandalwood leaves, the nitrogen content (figure 2) varied from 0.0084 to 0.0138 g per 1 g of leaves (0.84% to 1.38%) for different host combinations. variation of the phosphorus content (figure 3) was 0.0024 to 0.0036 g (0.24% to 0.36%); potassium content (figure 4) was 0.0060 to 0.0128 g (0.60% to 1.28%) and the variation of magnesium content was (figure 5) 0.0004 to 0.0010 g (0.04% to 0.10%). figure 2: mean nitrogen content (g) per 1 g of leaves of s. album grown with different combinations (+se). figure 3: mean phosphorus content (g) per 1 g of leaves of s. album grown with different combinations (+se). 0.000 0.004 0.008 0.012 0.016 n g p e r 1 g o f le a v e s host combination 0.000 0.001 0.002 0.003 0.004 p g p e r 1 g o f le a v e s host combination 24 figure 4: mean potassium content (g) per 1 g of leaves of s. album grown with different combinations (+se). figure 5: mean magnesium content (g) per 1 g of leaves of s. album grown with different combinations (+se). results revealed that the height growth enhancement of s. album is significantly different with different host combinations. the leaf nitrogen, phosphorus, potassium and magnesium contents of s. album grown with different hosts indicated no significant difference. the significant height growth of s. album could therefore be due to the absorption of water from the host trees via haustoria. 4. discussion s. album is an aggressive hemi-parasite with 70% of seedlings able to generate haustoria within 30 days from germination (nagaveni and srimathi, 1985). pongamia pinnata, casuarina equisetifolia and azadirachta indica were good hosts for s. album in india (nagaveni and vijayalakshmi, 2003). based on the results of this study, however, calliandra calothyrus, sesbenia grandiflora and acacia auriculiformis were identified as the most suitable host species that can be used in s. album plantation establishment in sri lanka. 0.000 0.005 0.010 0.015 0.020 0.025 k g p e r 1 g o f le a v e s host combination 0.0000 0.0003 0.0006 0.0009 0.0012 m g g p e r 1 g o f le a v e s host combinations subasinghe et al. /journal of tropical forestry and environment vol.9, no. 01 (2019) 19-26 25 both legumes and non-legumes were selected as potential host species in this study based on the importance and their ability of surviving under different climate conditions. however, extensive trials have shown that santalum species show improved growth and vigor when cultivated with leguminous hosts (annapurna et al., 2006; radomiljac et al., 1998; brand et al., 2000). this study also proved that the selected leguminous species, viz, c. calothyrus, s. grandiflora and a. auriculiformis bear the ability of enhancing the s. album growth over the other species used in the field trial. the presence of basic amino acids indicates that leguminous plants are more efficient hosts for sandalwood growth than non-leguminous plants. however, as radomiljac et al. (1998) and rocha et al. (2014) stated, the growth performances of s. album showed a variation in this study when planted with different legume host species. results of the present study also proved this because one legume, gliricidia sepium did not increase the s. album height as other legumes did. s. albums grown with host plants have shown higher contents of nitrogen, phosphorous and potassium in their leaves (rocha et al., 2014). in australia, s. spicatum growing near acacia acuminata had significantly shown higher foliar concentrations of nitrogen and potassium, and greater potassium to calcium ratio. increased concentrations of elements in the foliage of s. spicatum may relate to greater nutrient movement from a. acuminata to the parasite (brand et al., 2004). the nutrient analysis of the leaves of s. album conducted in this study indicated no significant difference when grown with legume and non-legume host species though nagaveni and vijayalakshmi (2003) stated that legume host species were capable of providing more of those nutrient contents than that of non-legumes. s. album absorbs water from the host species other than the nutrients (brand et al., 2000; tennekoon, 2000). water movements in three year old s. album planted in different regions of western australia were different with different host species (brand et al., 2000). this could be the reason of observing significant height growth increase of s. album in this study due to some host species over the others. 5. conclusion this study found that performance of s. album height growth is better when planted with legumes over the non-legumes although a significant difference of nitrogen, phosphorus, potassium and magnesium contents were not observed in leaves. therefore it can be suggested that the reason of significant height growth of s. album planted with some host species could be due to the absorption of the water in high quantities from those host species. among the tested host species, calliandra calothyrus was found to be the best followed by acacia auriculiformis and sesbenia grandiflora. acknowledgement authors acknowledge the financial assistance given by the national research council of sri lanka for this study (grant no. nrc 11-176). references annupurna, d., rathore, t.s. and joshi, g., 2006. modern nursery practices in the production of quality seedlings of indian sandalwood. journal of sustainable forestry, 22:33-35. barrett, d., 1998. nutrition studies on young sandalwood seedlings on the absence of hosts. sandalwood res. newsletter, 7, 1. brand, j.e., crombie, d.s. and mitchell, m.d., 2000. establishment and growth of sandalwood (santalum spicatum) in south-western australia: the influence of host species. australian forestry, 63:60-65. 26 brand, j., jones, p. and donovan, o., 2004. current growth rates and predicted yields of sandalwood (santalum spicatum) grown in plantations in south-western australia. sandalwood res. newsletter, 24:1-3. brand, j.e., norrisa, l.j. and dumbrella, i.c., 2012. estimated heartwood weights and oil concentrations within 16-year-old indian sandalwood (santalum album) trees planted near kununurra, western australia. australian forestry, 75:225-232. flora and fauna protection ordinance act, no 22 (amendment). 2009. published as a supplement to part ii of the gazette of the democratic socialist republic of sri lanka of april, 24:2009. fox j.e.d., 2000. sandalwood: the royal tree. biologist, 47:31. joulain, d., nengone, s.n., de guahma, d. and dit lyo, l., 2012. new insights into the qualitative and quantitative analytical chemistry of sandalwood essential oils new caledonia, france. proceedings of international sandalwood symposium, 21-24 october, 2012, honolulu, hawaii. kumar, a.n.a., joshi, g. and ram, h.y.m., 2012. sandalwood: history, uses, present status and the future. current science, 103:1408-1416. luong, t.m., lion, t., fox, j.e.d. and schatral, a., 2008. aspects of early growth and host relationships in the hemiparasitic santalum album: alternanthera taxa as primary hosts and growth in response to foliar feeding. international journal of ecology and environmental sciences, 34:7-17. nagaveni, h.c. and shrimathi, a.r., 1985. germination capacity of floating & inking sandal seeds. indian forester, 111:615-618. navageni, h.c. and vijayalakshmi, g., 2003. growth performance of sandal (santalum album l.) with different host species. sandalwood res. newsletter, 18:1-4. radomiljac, a.m., 1998. the influence of pot host species, seedling age and supplementary nursery nutrition on santalum album linn. (indian sandalwood) plantation establishment within the ord river irrigation area, western australia. forest ecology and. management, 102:193-201. rai, s.n., 1990. status and cultivation of sandalwood in india. sandalwood in the pacific, pp. 66-71. rangaswamy, c.r., jain s.h. and parthasarathi k., 1986. soil properties of some sandal bearing areas. van vigyan, 24:61-68. rao, p.s. and bapat, v.a., 1995. somatic embryogenesis in sandalwood (santalum album l.). somatic embryogenesis in woody plants, 193-210. rocha, d., ashokan p.k., santhoshkumar a.v., anoop, e.v. and sureshkumar, p., 2014. influence of host plant on the physiological attributes of field-grown sandal tree (santalum album). journal of tropical forest science, 26:166-172. somasekaran, t., 1997. arjuna’s atlas of sri lanka. arjuna consulting co., india subasinghe, s.m.c.u.p., 2013. sandalwood research: a global perspective. journal of tropical forestry and environment, 3:1-8. subasinghe, s.m.c.u.p., hettiarachchi, d.s., nawarathne b.s. and rohna, h.k., 2013. santalum album l. current status and research conducted in sri lanka. in m. nageshwara-rao, j.r. soneji and d.t.h. reymand (eds.) proceedings of the international sandalwood symposium 2012 held in honolulu, hawaii, lulu press inc., usa, 93-103 sundararaj, r. and muthukrishna, r., 2011 population dynamics of some coccids (coccoidea: hemiptera) infesting sandal (santalum album linn.) in bangalore, india. journal of forestry research, 22:259-262. tennekoon, k.u., ekanayake, s.p. and etampawala, e.r.l.b., 2000. an overview of santalum album research in sri lanka. sandalwood res. newsletter, 11:1-4. samarawickrama et al. /journal of tropical forestry and environment vol. 9, no. 01 (2019) 37-47 37 doi: https://doi.org/10.31357/jtfe.v9i1.3948 diversity of reptiles in the eastern and southern parts of the sinharaja rain forest samarawickrama v.a.m.p.k.1, kumara h.i.g.c.2*, samarawickrama d.r.n.s.3 1edward & christie (pvt) ltd. 64/10, nawala road, nugegoda, sri lanka 2department of geography, university of ruhuna, matara, sri lanka 3no.308/7a, warathenna, halloluwa, kandy, sri lanka date received: 05-04-2018 date accepted: 10-05-2019 abstract the sinharaja forest reserve is located in the southern as well as sabaragamuwa provinces in the wet zone, between latitudes 6o21-6o26 n and longitudes 80o21-80o34 e is one of the biologically unique tropical forest in sri lanka. although sinharaja is considered a lowland rain forest, the eastern part of the forest consists montane and sub-montane forests. many scholars have already researched on reptiles in the lowland rain forests of sri lanka including sinharaja, however, they have not significantly attended to the diversity of reptiles in the eastern and southern parts of the sinharaja forest. considering this gap, the research focuses on studying diversity of reptiles in diverse lowland rain forests, montane and sub-montane forests in the southern and eastern parts of sinharaja. giguruwa-kosmulla and pitadeniya sites in the southern part, and hadpanella and morningside in the eastern part are selected as study areas of the research. 16 line transects (as four from each site) and quadrate 16 samples (as four from each site) are used for primary data collecting. lowland rain forests, montane and sub-montane forests are identified as biologically sensitive habitats of reptiles. high number of native reptile species are recorded in lowland rain forests than in montane and sub-montane forests. 36 reptile species are identified in southern and eastern parts of the sinharaja forest and 19 species of them are endemic to sri lanka. among them, 05 vulnerable species, 04 endangered species, 05 critically endangered species are recorded. many threats have been found, however, among them issues of bio piracy loss of forest genetic resources and wildlife smuggling, illegal forest utilisation practices, gem mining, illegal forest encroachments and unethical tourism practices are major issues. thus, state forest department and other responsible authorities must attend to minimize the effects of these negative human impact on these vulnerable areas to protect sensitive reptile species in their habitats in order to conserve their diversity. key words: sinharaja forest reserve, lowland rain forests, montane sub-montane, reptiles, diversity 1. introduction the sinharaja forest reserve is a one of the biologically unique tropical forest in sri lanka. the forest spans over four administration districts namely, galle, matara, rathnapura and kalutara. the forest spreads over 11,187 hectares of land and an elevation range of 150-1,170 m. as a rainforest with rich and complex diversity of flora and fauna, sinharaja provides habitats for a variety of animals (kumara, 2010). importantly, the sinharaja forest is the last viable remnant of sri lanka's tropical lowland rain forests and more than 60% of the trees here which are very rare in other areas of the country are endemic to sri lanka (kumara, 2016). within the sinharaja forest, there are thousands of small streams of crystal cool fresh water making habitats for verity of fishes, toads, and crabs, especially for the endemic species. so, as a biological unit sinharaja holds a prominent place in the island (de zoysa and raheem, 1990). according to many scholars, reptile species have special ecological position to keep the balance of natural ecosystems and they are directly and indirectly contributing sustainability of *correspondence: chamindakumara03@yahoo.com tel: +94 714469539 issn 2235-9370 print/issn 2235-9362 online ©2019 university of sri jayewardenepura 38 ecosystems (atauri and de lucio, 2001; bomford et al., 2009; nijman and shepherd, 2011; blaustein et al., 2011). rain forest eco systems in the world provide habitats to reptile and facilitate their population dynamic and diversity (raxworthy and nussbaum, 1994; gehring et al., 2010). however, reptiles species are threatened with extinction due to the current trend of world rain forest bio system degradation (reider, 2013; jenkins et al, 2014). thus, it is important to attend immediately to protect and conserve numerous reptiles and their habitats in the world. rain forest eco-systems of sri lanka provide important habitats for many rare and endemic reptile species (kudavidanage et al., 2012). as a result, their diversity, behavior patterns, ecological role as well as habitats have intermittently been studied. for example; karunarathne and amarasinghe, have researched on ‘reptile diversity of a fragmented lowland rain forest patch in kukulugala area and they identified 708 individual reptiles belonging to 41 genera and 13 families. according to their findings, 44% of reptile species of this rain forest area are endemic to sri lanka and among them 19% are endangered (karunarathna and amarasinghe, 2011). same researchers have attended to a small-scale rain forest, namely, beraliya mukalana which is a proposed rain forest reserve situated in galle districts. even if the forest is considered small scale, they identified it as a biologically important habitat for sri lanka reptiles, since they found 35% endemic reptile species and among them one specie has been critically endangered, 3 are endangered, 6 are vulnerable, 14 are near-threatened and 4 are data-deficient (karunarathna and amarasinghe, 2012). sinharaja, which is the biggest rain forest of the island, is distinguished for its high biodiversity among all the rain forests of the island (neela and raheem, 1993).many scholars have contributed to generate knowledge regarding reptile in this forest (surasinghe, 2007; ishwaran and erdelen, 1990).71 reptile species are recorded in sinharaja and among them 34 are identified endemic species and 33 species have been declared nationally threatened species (bambaradeniya et al., 2003). many researchers have paid attention to diversity, potential threats and conservation needs of reptile and amphibian of sinharaja after 1990s (bambaradeniya et al., 2003; surasinghe and jayaratne, 2010). however, most of the researches about reptile are carried out in the northern section of sinharaja and a few researches are based on the eastern section of the sinharaja (morning site) since it has been identified a different biological unit and habitat for reptile species. according to jansen and bopage (2011), the eastern section of sinharaja which has different biological, geographical and environmental characteristics compared with the northern section of the forest has been identified as an exceptional area of sri lanka for its highly endemic reptile species. their diversity patterns depend on geo-spatial factors as well as time-special factors (hallam, 1974). various human and environmental factors have influenced to create diverse range of geo-special landscapes and ecosystems in the southern and eastern parts of sinharaja. even if many scholars have researched about reptiles in the low land rain forests of sri lanka including sinharaja (ishwaran and erdelen, 1990; de silva, 2006; kudavidanage et al., 2012), they have not paid enough attention on studying diversity of reptile in the southern and eastern parts of the sinharaja. number of habitats based on rain forest, montane and sub-montane forest such as primary forests, secondary forests, degraded forests, ridge forests, scrublands, forest patches, marshlands, riverine forests and abandoned chena cultivation lands can be seen in this area (figure 1) (wijesinghe and brooke, 2005). the literature survey of the research identified a potential ‘knowledge gap’ in nature of diversity of reptile in the southern and eastern parts of the forest and based on this gap the research objectives and questions were formed. considering this situation, this research focuses to examine diversity of reptile in the southern and eastern parts of the sinharaja rain forest. samarawickrama et al. /journal of tropical forestry and environment vol. 9, no. 01 (2019) 37-47 39 doi: https://doi.org/10.31357/jtfe.v9i1.3948 2. methodology a total of 30 days (12 hrs per day both day and night) have been spent on field work during april and november 2017. the study area (figure 1) stretched from giguruwa-kosmulla, pitadeniya hadpanella morningside in the sinharaja forest. the study was conducted in three different forest habitats in the area namely montane, sub-montane and low land rain forest. in each habitat, data were collected from five line transects (100 m×2 m) and quadrate sampling methods (8 m×8 m) per habitat. within each major habitat, different microhabitats (such as tree trunks, under rocks, tree holes, water puddles etc.) were searched for reptiles. three person were involved in the sampling of each transect. one person searched 1.5 m above on trees for arboreal species while a second person searched under logs, leaf litter, tree trunks etc. and a third person searched water puddles and streams. the different species of reptiles were handpicked or collected using a hand net and observed. no specimens have been collected, transported or deposited from the outside the forest. the species are identified in the field using diagnostic keys given by de silva (1980), greer (1991), wickramasinghe and somaweera (2003), whitaker and captain (2004), das and de silva (2005). after the survey period, some specimens are confirmed to species level using batuwita and bahir (2005), somaweera (2006), vogel and david (2006), batuwita & pethiyagoda (2007), manamendra-arachchi et al. (2007), wickramasinghe et al. (2007), maduwage et al. (2009), rooijen and vogel (2009), somaweera and somaweeera (2009), bauer et al. (2010), praschag et al. (2011), vogel and rooijen (2011) and conservation status was given according to iucn national red list. (the national red list 2012 of sri lanka 2012). figure 1: location of the study area. 3. results and discussion according to the findings, montane, sub montane forests and lowland rain forest can be identified biologically sensitive and important sites for reptile diversity. there are 209 native reptile species in sri lanka and among them 125 species are endemic to the island (biodiversity secretariat of the ministry of environment, 2012) while total of 36 reptile species are identified in the southern and eastern parts of the sinharaja forest and among them 19 species are endemic to sri lanka. while 5 40 vulnerable species, 4 endangered species, 5 critically endangered species. figure 2 showing species diversity comparison between the study area and the island. among the identified species, there were four species restricted to the sinharaja rain forest, including three agamid lizards namely ceratophora erdeleni, ceratophora karu, calotes desilvai and one gecko species cnemaspis pulchra, are endemic and critically endangered. according to the figure recorded tetrapod reptile species higher than recorded serpent species. figure 2: species diversity comparison between sri lanka and the study area (eastern sinharaja rain forest). all recorded species are belonging to 8 families. among them the highest number 15 species are recorded under family colubridae, including 5 endemic species. under family mabuyidae, 2 species are recorded while two of them are endemic to the island. figure 3 is showing more details. highest number of reptile species are recorded from the lowland rain forest than in sub montane and montane forests. due to vast range of micro habitats, habitat specific species and some of species flavoring specific climatic conditions, most of species are found there. following figures showing these habitats conditions. figure 3: family wise recorded species from the study area. 0 20 40 60 80 100 120 total species endemic total species endemic s ri l a n k a e a st e rn s in h e ra ja no.of species a re a n a m e serpent tetrapod reptile 9 2 4 14 2 3 1 7 2 2 4 1 2 0 2 4 6 8 10 12 14 16 agamidae gekkonidae scincidae colubridae elapidae viperidae varanidae no.of species f a m il y endemic number of species samarawickrama et al. /journal of tropical forestry and environment vol. 9, no. 01 (2019) 37-47 41 doi: https://doi.org/10.31357/jtfe.v9i1.3948 table 1: recorded reptile species from the study area. no family species common name national status 1 agamidae calotes calotes green garden lizard 2 agamidae calotes desilvai desilvas’ forest lizard e/cr 3 agamidae calotes liolepis whistling lizard / forest lizard e 4 agamidae calotes versicolor common garden lizard 5 agamidae ceratophora aspera rough horn lizard e/en 6 agamidae ceratophora erdeleni erdelen’s horn lizard e/cr 7 agamidae ceratophora karu karunaratne’s horn lizard e/cr 8 agamidae lyriocephalus scutatus lyre head lizard / hump snout lizard e/vu 9 agamidae otocryptis wiegmanni sri lankan kangaroo lizard e 10 gekkonidae cnemaspis pulchra rakwana day gecko e/cr 11 gekkonidae cyrtodactylus subsolanus rakwana forest gecko e/cr 12 ristellidae lankascincus fallax common lanka skink e 13 ristellidae lankascincus taprobanensis smooth lanka skink e/en 14 mabuyidae eutropisc carinata common skink 15 mabuyidae eutropis sp-01 skink 16 colubridae ahaetulla nasuta green vine snake 17 colubridae amphiesmas tolatum buff striped keelback 18 colubridae aspidura brachyorrhos boie’sroughside e/vu 19 colubridae atretium schistosum the olive keelback water snake 20 colubridae balanophis ceylonensis sri lanka keelback e/en 21 colubridae boiga barnesii barnes’s cat snake e/vu 22 colubridae boiga ceylonensis sri lanka cat snake 23 colubridae chrysopelea ornata ornate flying snake 24 colubridae coeloganthus helena trinket snake 25 colubridae dendrelaphis caudolineolatus gunther’s bronze back 26 colubridae lycodon carinata the sri lanka wolf snake e/en 27 colubridae lycodon aulicus wolf snake, house snake 28 colubridae oligodon arnensis common kukri snake/ banded kukri 29 colubridae oligodon sublineatus dumerul’ skuki snake e 30 colubridae ptyas mucosa rat snake 31 elapidae bungarus ceylonicus sri lanka krait / ceylon krait e/vu 32 elapidae naja naja indian cobra 33 viperidae daboia russelii russell’s viper 34 viperidae hypnale zara hump-nosed viper e/vu 35 viperidae trimeresurus trigonocephalus green pit viper e 36 varanidae varanus salvator water monitor e-endemic, cr-critically endangered, en-endangered, vu-vulnerable. 42 figure 4: species diversity in different forest habitats. the study carried out in three main habitats namely montane, sub montane and lowland rain forests. montane forests representing morningside and handapanella area. while lower handapanella and sinharaja monastery area representing sub montane forest habitats. pitadeniya, batuwangala and giguruwa area having low land rainforest habitats. 5 7 6 figure 5-7: lowland rainforest. figure 8: sub-montane rainforest. figure 9: montane rainforest. 0 5 10 15 20 25 30 montane forest sub-montane forest lowland rain forest n o .o f s p e c ie s habitat number of species endemic samarawickrama et al. /journal of tropical forestry and environment vol. 9, no. 01 (2019) 37-47 43 doi: https://doi.org/10.31357/jtfe.v9i1.3948 figure 10: ceratophora aspera figure 11: ceratophora karu figure 12: ceratophora erdeleni. figure 13: lyriocephalus scutatus figure 14: otocryptis wiegmanni figure 15: calotes liolepis figure 16: cnemaspis pulchra figure 17: mabuya sp.01 figure 18: boiga barnesii figure 19: cercaspis carinata 44 3.1 threats for reptile species some issues are identified as main threats to reptile habitats in both lowland rain forests and sub-montane forests. currently, wallapatta smuggling (gyrinops walla) has become a serious issue in giguruwa-kosmulla, pitadeniya as well as handapanella sites and it mainly contributes to accelerate the degradation of habitats of reptile and amphibian species. during our field research in the site, it is observed that people stay in the forest at nights for gathering forest materials, poaching and tree felling for timber (see below picture). these types of forest utilization practices have directly and negatively impacted on reptile habitats. four such huts used by people who illegally utilise forest resources to stay temporarily in the forest at nights are observed in the giguruwa-kosmulla site (see figures 21, 22,23,24,25 and 26). it is a serious issue in the handapanella area. this is a severe menace to small species such as reptiles and amphibians. forest ecosystems in the handapanella area have been used for illegal gem mining which is a threat to forest eco systems. during the fieldwork in the pitadeniya site, we observed that irresponsible tourist behaviour, especially, local tourists’ behaviour has negatively impacted on these systems. figure 23: illegal forest encroachments. figure 24: remains of pitfall trap used for poaching. figure 22: varanus salvator figure 20: hypnale zara figure 21: trimeresurus trigonocephalus samarawickrama et al. /journal of tropical forestry and environment vol. 9, no. 01 (2019) 37-47 45 doi: https://doi.org/10.31357/jtfe.v9i1.3948 figure 25-28: primary forest areas to extract wallapatta resin (gyrinops walla). 4. conclusion both lowland rain forests and sub-montane forests can be considered as biologically sensitive habitats of reptile’s species. high number of native reptile species’ habitats are located within lowland rain forests than in montane and sub-montane forests, however, highest parentage of endemic (e) and critically endangered (cr) species are recorded in the sub-montane forests, especially, in morningside area. currently this area is isolated from the sinharaja world heritage site therefore, it is necessary to conserve immediately, with jointing of the sinharaja world heritage site. there are many threats to the researched eco systems and issues of biopiracy. loss of forest genetic resources and wildlife smuggling, other illegal forest utilisation practices, gem mining, illegal forest encroachments and irresponsible tourism practices are major among them. thus, the state forest department and other responsible authorities must attend to minimise the impact of these possible threats to sensitive reptile habitats to protect their diversity. acknowledgement authors would like to acknowledge the small grant research programme of the ministry of mahaweli development & environment for financial assistance (grant no: 03/05/bd/19/011(2017)-01) and the department of forests and department of wildlife conservation for granting research permits to conduct this research. as well, many thanks to r.a.w.d.jayawardane, damith lakmal, d.h.g rajapaksha, manjula lankanth for their valuable assistants. also we must thankful to mr. prasanna samarawickrama for preparation of the location map. references atauri, j.a. and de lucio, j.v., 2001. the role of landscape structure in species richnesss of birds, amphibians, reptiles and lepidopterans in mediterranean landscapes. landscape ecology, 16:147-159. bambaradeniya, c.n.b., perera, m.s.j., perera, w.p.n., wickramasinghe, l.j.m., kekulandala, l.d.c.b., samarawickrema, v.a.p. and samarawickrema, v.a.m.p.k., 2003. composition of 27 28 25 26 46 faunal species in the sinharaja world heritage site in sri lanka. the sri lanka forester, 26:2140. batuwita, s. and bahir, m.m., 2005. description of five new species of cyrtodactylus (reptilia: gekkonidae) from sri lanka. in: yeo, d.c.j., ng, p.k.l. and pethiyagoda, r., contributions to biodiversity exploration and research in sri lanka. the raffles bulletin of zoology, 12:351-380. batuwita, s. and pethiyagoda, r., 2007. description of a new species of sri lankan litter skink (squamata: scincidae: lankascincus). ceylon journal of science (biological science), 36:8087. bauer, a, jackman, t. r, greenbaum, e., de silva, a., giri, v. b., and das, i., 2010. molecular evidence for the taxonomic status of hemidactylusbrookii group taxa (squamata: gekkonidae). herpetological journal, 20:129-138. biodiversity secretariat of the ministry of environment, 2012. the national red list 2012 of sri lanka, the biodiversity secretariat of the ministry of environment in collaboration with the national herbarium, colombo, sri lanka: department of national botanic gardens,. bomford, m., kraus, f., barry, s.c., lawrence, e., 2009. predicting establishment success for alien reptiles and amphibians: a role for climate matching. biological invasions, 11:713. das, i. and de silva, a., 2005. photographic guide to the snakes and other reptiles of sri lanka. pennsylvania, usa: new holland publishers. de silva, a., 2006. current status of the reptiles of sri lanka. in babaradeniya, c.n.b (ed) fauna of sri lanka: status of taxonomy, research and conservation, 134-163. colombo, sri lanka: iucn. de silva, p.h.d.h., 1980. snake fauna of sri lanka, with special reference to skull, dentition and venom in snakes. colombo, sri lanka: national museums of sri lanka. de zoysa, n. and raheem, r., 1990. sinharaja, a rain forest in sri lanka. colombo, sri lanka: march for conservation. gehring, p.s., ratsoavina, f.m. and vences, m., 2010. filling the gaps-amphibian and reptile records from lowland rainforests in eastern madagascar. salamandra, 46:214-234. greer, a.e., 1991. lankascincus, a new genus of scincid lizards from sri lanka with descriptions of three new species. journal of herpetology, 25:59-64. hallam, a., 1974. changing patterns of provinciality and diversity of fossil animals in relation to plate tectonics. journal of biogeography, 213-225. ishwaran, n. and erdelen, w., 1990. conserving sinharaja: an experiment in sustainable development in sri lanka. ambio, 237-244. jansen, p. and bopage, m., 2011. the herpetofauna of a small and unprotected patch of tropical rainforest in morningside, sri lanka. amphibians and reptiles conservation, 5:1-13. jenkins, r.k., tognelli, m.f., bowles, p., cox, n., brown, j. l., chan, l. and bora, p., 2014. extinction risks and the conservation of madagascar's reptiles. plos one, 9:100-173. karunarathna, d.m.s.s. and amarasinghe, a., 2012. reptile diversity in beraliyamukalana proposed forest reserve, galle district, sri lanka. taprobanica: the journal of asian biodiversity, 4:2027. kudavidanage, e.p., wanger, t.c., alwis, c., sanjeewa, s. and kotagama, s.w., 2012. amphibian and butterfly diversity across a tropical land‐use gradient in sri lanka; implications for conservation decision making. animal conservation, 15:253-265. kumara, h.i.g.c., 2010. the policy intervention and the trends in forest utilization by local communities in sinharaja (unpublished master of philosophy). university of peradeniya, kandy, sri lanka. kumara h.i.g.c., 2013. forest utilization by local communities in sinharaja rain forest: focused on policy interventions and trends. saarbrücken, germany: lap lambert academic publishing. kumara, h.i.g.c., 2016. challenges of biopiracy: implementing community based ecotourism (cbet) in the sri lankan context. journal of tropical forestry and environment, 6:36-49. kumara, h.i.g.c., 2016. challenges to implementing community based ecotourism (cbet) as a bottom up development approach in the sinharaja rain forest (sri lanka) (doctoral dissertation, university of waikato). samarawickrama et al. /journal of tropical forestry and environment vol. 9, no. 01 (2019) 37-47 47 doi: https://doi.org/10.31357/jtfe.v9i1.3948 kumara, h.i.g.c., 2017. challenges of biopiracy: implementing community based eco-tourism (cbet) in the sri lankan context, journal of tropical forestry and environment, 6:36-49. maduwage, k., silva, a., manamendra-arachchi, k. and pethiyagoda, r., 2009. a taxonomic revision of the south asian hump-nosed pit vipers (squamata: viperidae: hypnale). zootaxa, 2232:1-28. manamendra-arachchi, k., batuwita, s. and pethiyagoda. r., 2007. a taxonomical revision of the sri lankan day-geckos (reptilia: gekkonidae: cnemaspis), with description of new species from sri lanka and india. zeylanica, 7:9-122. nijman, v. and shepherd, c.r., 2011. the role of thailand in the international trade in cites-listed live reptiles and amphibians. plos one, 6:7825. praschag. p., stuckas, h., packert, m., maran, j. and fritz, u., 2011. mitochondrial dna sequences suggest a revised taxonomy of asian flapshell turtles (lissemys smith, 1931) and the validity of previously unrecognized taxa (testudines: trionychidae). vertebrate zoology, 61:147-160. raxworthy, c.j. and nussbaum, r.a., 1994. a rainforest survey of amphibians, reptiles and small mammals at montagne d'ambre, madagascar. biological conservation, 69:65-73. reider, k.e., carson, w.p. and donnelly, m.a., 2013. effects of collared peccary (pecaritajacu) exclusion on leaf litter amphibians and reptiles in a neotropical wet forest, costa rica. biological conservation, 163:90-98. rooijen, j.v. and vogel, g., 2009. a multivariate investigation into the population systematics of dendrelaphistristis (daudin, 1803) and dendrelaphisschokari (kuhl, 1820): revalidation of dendrophischairecacos boie, 1827 (serpentes: colubridae). herpetological journal, 19:193200. somaweera, r. and somaweera, n., 2009. lizards of sri lanka: a colour guide with field keys. frankfurt am main, german: edition chimaira/serpent's tale nhbd. somaweera, r., 2006. snakes of sri lanka (sinhala text).colombo. sri lanka: wildlife heritage trust of sri lanka. surasinghe, t., jayaratne, r., 2010. diversity, threats and conservation of herpetofauna in and around the eastern sinharaja. sabaragamuwa university journal, 6:3-12. surasinghe, t.d., 2007. conservation overview of herpetofauna of sinharaja man and biosphere reserve of sri lanka. zoos' print journal, 22:2535-2538. vogel, g. and david, p., 2006. on the taxonomy of the xenochrophis piscator complex (serpentes, natricidae). in proceedings of the 13th congress of the societas europaea herpetologica, 241246. vogel, g. and rooijen, j.v., 2011. a new species of dendrelaphis (serpentes: colubridae) from the western ghats-india. taprobanica, 3:77-86. whitaker, r. and captain, a., 2004. snakes of india: the field guide. mumbai, india: draco publication limited. wickramasinghe, l.j.m. and somaweera, r.k., 2003. distribution and current status of the endemic geckos of sri lanka. gekko, 3:2-13. wickramasinghe, l.j.m., rodrigo, r., dayawansa, n. and jayantha, u.l.d., 2007. two new species of lankascincus (squamata: scincidae) from sripada sanctuary (peak wilderness), in sri lanka. zootaxa, 1612:1-24. wijesinghe, m.r., brooke, m.d.l., 2005. impact of habitat disturbance on the distribution of endemic species of small mammals and birds in a tropical rain forest in sri lanka. journal of tropical ecology, 21:661-668. wakawa et al. /journal of tropical forestry and environment vol. 8, no. 02 (2018) 69-81 69 state of a lowland tropical forest in south-west nigeria l.d. wakawa1٭, f.n. ogana2 and t.e. adeniyi2 1department of forestry and wildlife management, federal university gashua, gashua, yobe state, nigeria 2 department of social and environmental forestry, university of ibadan, nigeria date received: 2018-03-27 date accepted: 2018-11-20 abstract forests play a significant role in human existence and survival. timely and reliable information on the status of a forest is essential for assessing the extent of regeneration and degradation. however, when such information is lacking effective forest management practices becomes impossible. therefore, this study assessed the tree species diversity, richness and structure of oluwa forest reserve with the view of ascertaining it present state which is crucial for management and conservation purposes. to achieved these, a systematic line transect was used in the laying of eight (8) temporary sample plots (tsps) of size 50m x 50m. trees with dbh≥10cm in the selected plots were enumerated, identified and measured. the results indicate that 535 individual trees were enumerated cutting across 26 families and 58 species. the reserve has the margalef's index of species richness, shannon-weiner diversity index (h') and pielou's species evenness index (eh) of 9.07, 3.43 and 0.84 respectively. the forest has a mean dbh (cm), mean height (m), total basal area/ha (m2) and total volume/ha (m3) of 24.7, 16.9, 36.63 and 602.09 respectively. majority of trees were found in the smaller diameter and height classes; giving rise to reverse j-shaped structure. the structure of oluwa forest reserve has been altered significantly while the species diversity and richness seems to indicate a sign of improvement compared to previous studies. with proper management, the remaining fragmented forests could regenerate and replenish to save some of the original species composition of the reserve. keywords: lowland tropical forest, tree species diversity, forest structure, forest conservation 1. introduction forest worldwide provides a wide range of economic, environmental and cultural benefits and services to people (maini, 1992). the tropical forest is regarded as one of the most endowed ecosystems in the world (thomas and baltzer, 2002; harrison, 2005) and home to more than half of the total number of species worldwide (thomas and baltzer, 2002). majority of the global biodiversity hotspots identified worldwide are reported to be in the tropical forests (mittermeier et al., 2004). nigeria has eight tropical ecological zones which are broadly categorized into three namely; the tropical rainforest ecosystem, the mangrove in the southern part and the savannah in the northern part (adekunle et al., 2013). oluwa forest reserve lies in the lowland tropical rain forest of south-west nigeria. the lowland rain forests of south-west nigeria play significant role in the biological and socioeconomic aspect of the nation (ogunsesan et al., 2011). the communities residing within and around the forest reserve derive their source of livelihood from it, either from the timber products or nontimber forest products (ntfps) for food, medicinal and other domestic purposes. the continuous increase of the country’s population has resulted to increased exploitation of forest resources. *correspondence: luckywakawa@fugashua.edu.ng issn 2235-9370 print/issn 2235-9362 online ©2017 university of sri jayewardenepura mailto:luckywakawa@fugashua.edu.ng 70 despite of the importance of these forests, 18.56% of the natural forest in nigeria has been lost between 2000 and 2010 and regarded as one out of five countries in the world with the highest annual rate of deforestation for the period (global forest resource assessment (fra) 2010). this also includes the fragmentation and degradation of many forest reserves. as a result, many important tropical forest tree species have also gone into extinction while many are vulnerable, rare or endangered as reported by adekunle et al., (2004). adekunle (2006) and ogunjemite (2015) reported a decline in species richness and diversity in 2 tropical forest reserves (omo and shasha) and ologbo forest concession respectively in nigeria. similarly, naidu and kumar (2016) found out, that the biodiversity of the tropical forests in eastern ghats of andhra pradesh, india are under threat because of anthropogenic and upcoming mining activities. however, a study conducted a decade ago in oluwa forest reserve by onyekwelu et al., (2008) indicates a semblance of recovery from decades of destruction. this may be attributed to better protective strategies adopted by the forestry department or the resilience nature of the reserve. several studies had also been carried out with respect to species diversity in different part of the world (wittmann et al., 2008; jayakumar et al., 2011; adekunle et al., 2013; hu et al., 2015; rao et al., 2015) which shows the state of those forest. indiscriminate logging activities in both protected and unprotected forest is derived by the monetary gains accrued from it (adekunle et al., 2010) and is one of the major causes of declined in species diversity and richness in the forest. other factors responsible for the decline in forest reserve according to adekunle et al., (2010) includes; dearth of manpower and capacity of staff of forestry department, obsolete laws and stoppage of payment of annual royalty. although as discussed above, several studies had been conducted in different part of the world and oluwa forest reserve in particular, there is still dearth of information with respect to number and distribution of species worldwide (pimm et al., 2014). furthermore, there is the need to determine the status of a forest over time, so that the extent of regeneration and depletion can be assessed. globally, there is growing interest in assessing species diversity, composition and richness of degraded forest fragments (myers et al., 2000). recent and reliable information on the status of a forest reserve is very important. information on species composition, structure, richness, diversity helps us in understanding the dynamics in forest ecosystems and the management system that can be applied (akinyemi and oke, 2014). this study is therefore aimed at assessing the status of oluwa forest reserve. this will provide information on the rate of depletion and possible regeneration in the forest. this information is crucial for monitoring and sustaining the phytodiversity of the forest. it will also help in understanding the threats been faced by the forest and appropriate conservation strategies that could be applied. 2. materials and methods 2.1 study area this study was carried out in oluwa forest reserve located in the moist tropical rainforest zone of nigeria. it occupies an area of about 629 km2 with much of it lying approximately between 300 and 600 m above sea level (ogunjemite et al., 2006). the natural forest covers about 8 km2 (approximately 800 ha) of the forest reserve. the reserve is situated in odigbo local government area of ondo state, nigeria and lies between latitude 6.83°-6.91°n and longitude 4.52°-4.59°e (figure 1). annual rainfall ranges from 1700 to 2200 mm. annual mean temperature in oluwa is 26° c. the relative humidity is high and uniform, ranging from 75% (afternoon) to 95% (morning). soils are predominantly ferruginous tropical. the natural vegetation of the area is tropical rainforest characterised by emergent with multiple canopies and lianas. wakawa et al. /journal of tropical forestry and environment vol. 8, no. 02 (2018) 69-81 71 figure 1: map of oluwa forest reserve, ondo state, nigeria (source: ogana et al., 2015). 2.1 sampling procedure, data collection and processing in this study, systematic sampling technique was used in the laying of the temporary sample plots in the 8 km2 natural forest. two transects of 500 m in length with a distance of 200 m between the two parallel transects were laid. sample plots of 50x50 m in size were established in alternate position along each transect at 100 m interval; summing up to 4 plots per 500 m transect and a total of 8 plots in the study area. living trees with diameter at breast height (dbh)≥10.0 cm in the quadrats were enumerated, identified by their botanical name using trees of nigeria (keay, 1989) and a taxonomist. the dbh measurement was done using a diameter tape. the data collected were grouped into species and families, and the following stand variables were computed from the inventory data: mean diameter, minimum diameter, maximum diameter, number of trees per hectare and basal area. analysis the important quantitative analysis such as density, frequency, abundance of tree species and relative dominance were determined according to curtis and mcintosh (1950). density (1) frequency (%) (2) abundance (3) 72 relative density the relative density was calculated according to brashears et al., (2004) equation (4) where; rd = relative density ni = number of individual of the species n = number of individual of all species relative dominance it was calculated according curtes and mcintosh (1950) given as; (5) where; rdom.= relative dominance of the species gi = total basal area for a particular species gn = total basal area of all the species diversity indices paleontological statistics (past) version 3.19 software for ecological analysis was used in assessing the diversity indices (margalef's index of species richness, pielou's species evenness index (eh), shannon-weiner index (h') and simpson index of dominance (d)) tree diameter and height characterisation three-parameter log-logistic (3p) distribution was used to describe the diameter and height structure of the natural forest using the method of maximum likelihood. the probability density function (pdf) and cumulative distribution function (cdf) of the log-logistic distribution are given by: (6) (7) where; =probability density function =cumulative distribution function x=diameter/height =shape parameter =scale parameter =location parameter wakawa et al. /journal of tropical forestry and environment vol. 8, no. 02 (2018) 69-81 73 3. results 3.1 family distribution a total of five hundred and thirty-five (535) trees were enumerated cutting across twenty-six (26) families and fifty-eight (58) tree species (table 1). the family sterculiaceae recorded the highest number of species (10) representing 17.24% and occurrence (112) representing 20.93%. the family apocynaceae recorded seventy-four (74) number of occurrence representing 13.83%, ulmaceae has 59 representing 11.03%, euphorbiaceae has 50 representing 9.35%, meliaceae recorded seven (7) numbers of species representing 12.07% and 42 number of occurrence representing 7.85% while moraceae recorded five (5) numbers of species representing 8.62% and twenty-six (26) number of occurrence representing 4.86%. the family verbenaceae, mimosoideae, loganiaceae and chrysobalanaceae recorded the least number of species and stand with each recording 1 respectively; representing 1.72% and 0.02% respectively (table 1). table 1: family distribution of tree species in oluwa forest reserve. family no. of species no. of observation anacardiaceae 2 4 annonaceae 1 11 apocynaceae 2 74 bombacaceae 2 4 boraginaceae 1 13 burseraceae 1 2 caesalpinaceae 5 30 chenopodiaceae 1 5 chrysobalanaceae 1 1 combretaceae 1 11 ebaneceae 1 25 euphorbiaceae 3 50 guttiferae 1 4 irvingiaceae 2 5 loganiaceae 1 1 meliaceae 7 42 mimosoideae 1 1 moraceae 5 26 myristicaceae 2 15 olacaceae 2 6 rubiaceae 2 7 rutaceae 1 3 sapotaceae 1 23 sterculiaceae 10 112 ulmaceae 1 59 verbenaceae 1 1 total 26 58 535 74 3.2 species distribution and stand variables celtis zenkeri had the highest number of occurrence, recording fifty-nine (59) number of tree per hectare representing 11.02% followed by picralima nitida which recorded fifty-five (55) representing 10.28% (table 2). 37 stems of ricinodendron heudelotii, 31 stem of buchholzia coriacea, 25 stems of diospyros crassiflora and lovoa trichilioides and 23 stem of malacantha alnifolia representing 6.92%, 5.79%, 4.67% and 4.30%, respectively were also recorded. albizia ferruginea, anthocleista djalonensis, carapa procera, cola millenii, distemonanthus benthamianus, ficus letea, hannoa klaineana, mansonia altissima, maranthes robusta, mitragyna stipulosa, olax subscorpioidea, spondias mombin, vitex grandifolia recorded 1 representing 0.19% of stand making them the tree species with the least number of occurrence in the reserve (table 2). the species celtis zenkeri, picralima nitida, ricinodendron heudelotii, buchholzia coriacea, lovoa trichilioides and diospyros crassiflora are among the species with the highest important value index (ivi) of 53.81, 49.51, 43.96, 27.86, 23.18 and 22.24, respectively while the species with the least important value index are distemonanthus benthamianus, hannoa klaineana, mansonia altissima, maranthes robusta, mitragyna stipulosa, olax subscorpioidea, spondias mombin, vitex grandifolia recording 0.88 each (table 2). in terms of relative density, celtis zenkeri, picralina nitida, ricinodendron heudelotii, buchholzia coriacea, diospyros crassiflora and berlinia grandiflora are some of the species with the highest value of 101.7, 94.8, 63.8, 53.4, 43.1 and 34.5, respectively while anthocleista djalonensis, ficus letea, mansonia altissima, maranthes robusta and vitex grandifolia were some of the species which recorded the least value of 1.7 each (table 2). diversity indices the forest reserve has a species richness of 9.07, species evenness of 0.84, shannon-weiner diversity index (h') of 3.43, pielou's species evenness index (eh) of 0.84 and simpson index of dominance (d) of 0.95 (table 3). the mean dbh of the trees in the forest was 24.7cm, dominant dbh was 118.5 cm, mean height was 16.9, dominant height was 63.7 m, total basal area was 36.63 m2/ha and a total volume of 602.09 m3/ha (table 3). wakawa et al. /journal of tropical forestry and environment vol. 8, no. 02 (2018) 69-81 75 table 2: tree species distribution and stand variables of oluwa forest reserve. species n/ha mdbh mht g/ha vol/ha density frequency (%) abundance rd% rdom%. ivi afzelia bipindensis 3 48.1 26.0 0.57 7.06 0.38 25.0 2 5.2 1.54 3.36 albizia ferruginea 1 22.2 13.8 0.04 0.34 0.13 12.5 1 1.7 0.11 0.91 anthocleista djalonensis 1 12.8 7.4 0.01 0.05 0.13 12.5 1 1.7 0.04 0.88 anthostema aubreyanum 3 17.2 16.2 0.07 0.63 0.38 12.5 3 5.2 0.19 2.68 antiaris welwitschii 3 42.3 28.0 0.60 13.91 0.38 37.5 1 5.2 1.64 3.41 berlinia grandiflora 20 19.5 17.4 0.70 8.47 2.50 50.0 5 34.5 1.91 18.19 bombax buonopozense 2 26.2 16.8 0.11 1.79 0.25 25.0 1 3.4 0.30 1.87 brachystegia eurycoma 3 62.9 31.6 1.36 39.95 0.38 37.5 1 5.2 3.71 4.44 buchholzia coriacea 31 17.5 12.1 0.83 7.74 3.88 87.5 4 53.4 2.28 27.86 canarium schweinfurthii 2 24.8 18.2 0.11 1.38 0.25 12.5 2 3.4 0.29 1.87 carapa procera 1 15.9 11.1 0.02 0.14 0.13 12.5 1 1.7 0.05 0.89 cassia sieberiana 3 15.6 7.3 0.06 0.29 0.38 37.5 1 5.2 0.16 2.67 cedrela odorata 2 25.8 14.2 0.11 0.93 0.25 25.0 1 3.4 0.29 1.87 ceiba pentandra 2 23.8 17.1 0.09 0.97 0.25 25.0 1 3.4 0.25 1.85 celtis zenkeri 59 20.2 15.1 2.16 24.68 7.38 100.0 7 101.7 5.89 53.81 chenopodium ambrosioides 5 19.2 13.4 0.15 1.51 0.63 50.0 1 8.6 0.41 4.52 cleistopholis patens 11 37.6 17.6 1.56 20.83 1.38 50.0 3 19.0 4.27 11.62 cola acuminata 2 25.8 12.9 0.12 0.82 0.25 25.0 1 3.4 0.33 1.89 cola millenii 1 23.7 15.8 0.04 0.38 0.13 12.5 1 1.7 0.12 0.92 cordia millenii 13 27.4 19.9 1.03 21.42 1.63 100.0 2 22.4 2.81 12.61 diospyros crassiflora 25 15.3 11.2 0.51 4.92 3.13 100.0 3 43.1 1.38 22.24 distemonanthus benthamianus 1 18.1 18.5 0.03 0.35 0.13 12.5 1 1.7 0.07 0.90 entandrophragma angolense 6 21.1 18.0 0.24 3.97 0.75 37.5 2 10.3 0.66 5.50 entandrophragma cylindricum 3 19.2 15.3 0.09 0.91 0.38 25.0 2 5.2 0.25 2.71 ficus letea 1 11.5 7.3 0.01 0.04 0.13 12.5 1 1.7 0.03 0.88 ficus mucuso 17 23.2 17.6 0.81 9.46 2.13 75.0 3 29.3 2.22 15.77 funtumia elastica 19 20.7 14.2 0.75 8.52 2.38 87.5 3 32.8 2.04 17.40 garcinia kola 4 18.2 14.8 0.11 1.07 0.50 37.5 1 6.9 0.29 3.59 guarea cedrata 2 12.0 10.6 0.02 0.10 0.25 12.5 2 3.4 0.06 1.75 hannoa klaineana 1 27.0 22.6 0.06 1.07 0.13 12.5 1 1.7 0.16 0.94 irvingia gabonensis 4 26.3 23.6 0.23 3.16 0.50 25.0 2 6.9 0.63 3.76 khaya ivorensis 3 51.7 35.1 0.79 20.45 0.38 37.5 1 5.2 2.17 3.67 76 lannea welwitschii 3 23.3 19.4 0.17 4.00 0.38 25.0 2 5.2 0.47 2.82 lovoa trichilioides 25 22.3 15.9 1.19 16.95 3.13 100.0 3 43.1 3.26 23.18 malacantha alnifolia 23 20.6 16.4 0.88 12.59 2.88 75.0 4 39.7 2.42 21.04 mansonia altissima 1 13.2 11.9 0.01 0.12 0.13 12.5 1 1.7 0.04 0.88 maranthes robusta 1 12.8 7.9 0.01 0.04 0.13 12.5 1 1.7 0.04 0.88 milicia excelsa 3 17.5 14.0 0.08 0.70 0.38 37.5 1 5.2 0.21 2.69 mitragyna stipulosa 1 33.2 23.4 0.09 1.35 0.13 12.5 1 1.7 0.24 0.98 musanga cecropioides 2 42.4 31.5 0.40 7.47 0.25 12.5 2 3.4 1.10 2.27 nesogordonia papaverifera 5 14.7 10.7 0.09 0.52 0.63 50.0 1 8.6 0.24 4.43 olax subscorpioidea 1 39.0 20.5 0.12 1.62 0.13 12.5 1 1.7 0.33 1.03 pausinystalia johimbe 6 31.3 16.9 0.51 6.35 0.75 50.0 2 10.3 1.38 5.86 picralima nitida 55 17.6 12.8 1.53 16.00 6.88 100.0 7 94.8 4.19 49.51 pterygota bequaertii 18 31.1 20.3 2.45 61.63 2.25 62.5 4 31.0 6.70 18.87 pterygota macrocarpa 9 35.5 18.3 1.50 19.22 1.13 75.0 2 15.5 4.10 9.81 pycnanthus angolensis 9 37.6 27.6 1.27 30.45 1.13 62.5 2 15.5 3.46 9.49 ricinodendron heudelotii 37 51.5 24.8 8.84 148.64 4.63 87.5 5 63.8 24.14 43.96 spondias mombin 1 41.0 25.6 0.13 2.42 0.13 12.5 1 1.7 0.36 1.04 staudtia stipitata 6 17.7 12.9 0.16 1.27 0.75 50.0 2 10.3 0.44 5.39 sterculia rhinopetala 14 26.3 20.3 0.87 13.65 1.75 75.0 2 24.1 2.37 13.26 sterculia tragacantha 15 19.2 17.0 0.51 5.57 1.88 100.0 2 25.9 1.38 13.62 strombosia pustulata 5 20.4 17.5 0.18 2.55 0.63 37.5 2 8.6 0.50 4.56 terminalia superba 11 18.0 16.0 0.30 4.07 1.38 87.5 2 19.0 0.82 9.89 triplochiton scleroxylon 16 28.7 22.3 1.22 26.59 2.00 100.0 2 27.6 3.32 15.45 uapaca heudelotii 10 23.9 15.8 0.63 10.51 1.25 25.0 5 17.2 1.71 9.48 vitex grandifolia 1 14.3 10.7 0.02 0.09 0.13 12.5 1 1.7 0.04 0.88 zanthoxylum leprieurii 3 17.7 11.2 0.09 0.41 0.38 25.0 7 5.2 0.24 2.70 n/ha = number of tree per ha; mdbh = mean diameter at breast height; mht = mean total height; g/ha = basal area per ha; vol/ha = volume per ha; rd = relative density in percentage; rdom = relative dominance in percentage; ivi = important value index. wakawa et al. /journal of tropical forestry and environment vol. 8, no. 02 (2018) 69-81 77 table 3: diversity indices and growth variables of oluwa forest reserve. biodiversity indices tree growth variables indices values variables values margalef's index of species richness 9.07 mean dbh (cm) 24.7 pielou's species evenness index (eh) 0.84 dominant dbh (cm) 118.5 shannon-weiner index (h') 3.43 mean height (m) 16.9 simpson index of dominance (d) 0.99 dominant height (m) 63.7 total basal area/ha (m2) 36.63 total volume/ha (m3) 602.09 forest structure the graphical distributions of the observed number of tree (n/ha) and the fitted log-logistic distribution by diameter (dbh) and height classes were clear indication of the typical nature of a natural forest. majority of trees were found in the smaller diameter and height classes; giving rise to reverse jshaped structure (figure 2 and 3). the log-logistic distribution described the structure of the forest perfectly well. figure 2: diameter (dbh) distributions of the natural forest in oluwa forest reserve. figure 3: the height distributions of the natural forest in oluwa forest reserve. 78 4. discussion 4.1 family distribution the forest reserve is dominated by species in the family sterculiaceae, apocynaceae, ulmaceae, euphorbiaceae, meliaceae and moraceae. prominent species in these families includes; buchholzia coriacea, funtumia elastica,mansonia altissima, triplochiton scleroxylon,cola acuminata, celtis zenkeri, ricinodendron heudelotii, khaya ivorensis, entandrophragma species, milicia excelsa, ficus and antiaris species. our findings correspond with that of onyekwelu et al., (2008) who reported a similar trend in family and species distribution in oluwa forest reserve, although the number of families and species reported by him (24 and 45 respectively) is less than what we encountered (26 and 58 respectively). the difference could be attributed to the difference in the size of plot used and space (time) over which the studies were carried out. sample size is one of the factors that determine the actual diversity status of an ecosystem (jayakumar et al., 2011). the larger the size of the plot, the likelihood of identifying many number of species (kindt and coe, 2005). 50×50 m plots were used against 20×20 m used by onyekwelu et al., (2008) which could be one of the reasons why more family and species were identified in this study against that reported by onyekwelu et al., (2008). with proper management the difference in space or time (about 10 years) between when the two studies were conducted could possibly result in increasing species population due to regeneration process in the forest. adekunle et al., (2013) also reported 95, 31 and 387 number of species, family and individual trees, respectively in a strict nature reserve in akure, ondo state, nigeria. also, aigbe and omokhua (2015) reported 72, 30 and 808 number of species, family and individual trees, respectively in a tropical rain forest in nigeria (oban forest reserve) while 165 tree species and 50 families was reported by rao et al., (2015) in tropical forest in india. apart from the difference in plot size and space, variation in environmental conditions is another possible reason for the observed differences between different results from different tropical forest. 4.2 species distribution and stand variables important timber species commonly found in the tropical low land forest of the southwest such as khaya ivorensis, mansonia altisima, milicia excelsa are at verge of extinction in the forest reserve. this is because only 3, 1, 3 stems, respectively of these species were encountered in the study area signaling a great threat to the survival of these important tree species. illegal timber harvesting within the forest reserve is the major reason for this observed trend. for example, adekunle et al., (2010) reported the exploitation of 111,777 tropical rainforest hardwood species in ondo state forest reserve between 2003 and 2010. however, the relatively fair presence of species such diospyros crassiflora (4.67%) a rare and banned species of the tropical lowland forest of nigeria is an indication that the reserve is still an important conservation site. celtis zenkeri is the dominant tree species in the forest reserve since it has the highest important value index and relative density while anthocleista djalonensis, ficus letea, mansonia altissima, maranthes robusta and vitex grandifolia are the less dominants species in the forest reserve. this implies that despite the rampant illegal logging activities taken place in the reserve, celtis zenkeri has withstand the pressure. this could be because of the large number of the species or fast regeneration process. however, species such as mansonia altisima etc. with the least important value index and relative density may likely disappear from the forest in no distant future if adequate conservation efforts are not put in place. this finding agrees with adekunle et al., (2013) who reported celtis zenkeri to be the abundant tree species in tropical rainforest of akure strict forest reserve, ondo state. 4.3 diversity indices the forest reserve can be said to be averagely rich, though the richness is far below that reported by adekunle et al., (2010) in akure forest reserve, this is not surprising considering the level of protection in akure forest reserve which is a strict nature reserve (snr) in comparison with oluwa forest reserve. however, the value is a bit below that reported by aigbe and omokhua (2015) and oban forest reserve respectively, this shows the level of exploitation in oluwa forest reserve in comparison to the two other reserves. in terms of relative abundance or diversity signified by the shannon-weiner diversity index, the wakawa et al. /journal of tropical forestry and environment vol. 8, no. 02 (2018) 69-81 79 reserve can be regarded to be fairly abundant or diverse, more diverse than tropical rainforest part of ologbo forest concession (ogunjemite, 2015). however, it is less diverse than akure and oban forest reserve (aigbe and omokhua 2015; adekunle et al., 2013). surprisingly, the total basal area in the forest reserve is more than that reported in akure forest, oban forest reserve and rainforest part of ologbo forest concession (adekunle et al., 2013; aigbe and omokhua 2015; ogunjemite, 2015). since total basal area is an indication of productivity, it means oluwa forest reserve is more productive than the three forest reserve. there are larger trees in oluwa forest reserve and these contribute more to basal area per hectare than smaller trees. the difference in sample size, plot size, environmental conditions, and other site factors could be responsible for the observation (aigbe and omokhua, 2015). 4.4 forest structure the tree storey layer in the forest is skewed toward lower stratum, a complete deviation from the characteristically complex vertical structure of forest canopies of low land tropical rainforest. only a few species are found in the middle and upper layer while noting exist in the emergent layer. this implies to the level of exploitation that has took place or is currently taking place. this is not surprising because logger’s species of interest usually falls within the upper and middle stratum of the forest. a similar observation was made by adekunle et al., (2004) and ogunjemite (2015) in omo and ala forest reserve and the tropical rainforest part of ologbo forest concession, respectively. majority of the trees in the forest also fell below the maturity level (≤40cm) just like what adekunle et al., (2013) observed in akure forest reserve. the small height and diameter size of the trees in the forest is an indication of abundance of young trees occasioned by excessive exploitation of mature tree species, gaps are created making light, water available for regeneration. although the forest structure has been altered to a large extent, with adequate conservation effort, the relatively young trees can mature in the near future. 5. conclusion conclusively, it is evident from the results that oluwa forest reserve structure and composition has been altered considerably over time as a result of anthropogenic activities. notwithstanding, the forest still contains some important tropical forest species such as diospyros crassiflora, milicia excelsa, khaya ivorensis, mansonia altisima, triplochiton scleroxylon, entandrophragma species and structure reminiscence of an ideal tropical rainforest. there seems to be improvement in species richness and diversity if previous study more especially that of onyekwelu et al. (2008) is to be compared with. this goes to show the resilence nature of the forest and indicate the ability of the remaining fragmented forest to regenerate and replenish to save some of the original species composition of the reserve given the right atention. acknowledgement the authors are thankful to ajetomobi oluwadamilola and young igbinosa e. for their assistance during data collection 80 references adekunle, v.a.j. (2006). conservation of tree species diversity in tropical rainforest ecosystem of southwest nigeria. journal of tropical forest science, 18(2): 91–101. adekunle, v.a., olagoke, a.o., akindele, s.o. (2013). tree species diversity and structure of a nigerian strict nature reserve. tropical ecology, 54(3): 275-289. adekunle, v.a., akindele, s.o., fuwape, j.a. (2004). structure and yield models of tropical lowland rainforest ecosystem of southwest nigeria. food, agriculture & environment, 2(2):395-399. adekunle, v.a., olagoke, a.o., ogundare, l.f. (2010). rate of timber production in a tropical rainforest ecosystem of southwest nigeria and its implications on sustainable forest management. journal of forestry research, 21:225-230. aigbe, h.i., omokhua, g.e. (2015). tree species composition and diversity in oban forest reserve, nigeria. journal of agricultural studies, 3(1): 10-24. akinyemi, d.s., oke, s.o. (2014). floristic composition and structural diversity of shasha forest reserve in ile-ife, southwestern nigeria. not sci biol, 6(4):433-440. brashears, m. b., fajvan, m. a., schuler, t. m. (2004). an assessment of canopy stratification and tree species diversity following clearcutting in central appalachian hardwoods. forest science, 50: 54-64. curtis, j.t., mcintosh, r.p. (1950). the interrelations of certain analytic and synthetic phytosociological characters. ecology, 31: 434-455. fra (2010). global forest resources assessment 2010, main report. fao forestry paper, 163, fao rome, pp. 340 hu, y., su, z., li, w., li, j., ke, x. (2015). influence of tree species composition and community structure on carbon density in a subtropical forest. plos one, 10(8):0136984. jayakumar, s., kim, s., heo, j. (2011). floristic inventory and diversity assessment a critical review proceedings of the international academy of ecology and environmental sciences, 1(3-4):151168. keay, r.w.j. (1989). trees of nigeria. a revised version of nigerian trees (vols. 1 & 2) eds. keay, r.w.j. kindt, r., coe, r. (2005). tree diversity analysis. a manual and software for common statistical methods for ecological and biodiversity studies. nairobi: world agroforestry centre (icraf). maini, j.s. (1992). sustainable development of forests: an international journal of forestry and forest industries vol. 43 –n0. 169 1992/2fao food and agriculture organization of the united nation mittermeier, r.a., robles-gil, p., hoffman, m., pilgrim, j.d., brooks, t., mittermeier, c.g., da fonseca, g.a. (2004). hot spots revisited: earth’s biologically richest and most endangered terrestrial ecoregions. mexico city, mexico: conservation international in association with cemex myers, n., mittermeier, r.a., mittermeier. c.g., da fonseca, g.a., kent, j. (2000). biodiversity hotspots for conservation priorities. nature, 403:853-858. naidu, m.t., kumar, o.a. (2016). tree diversity, stand structure, and community composition of tropical forests in eastern ghats of andhra pradesh, india. journal of asia-pacific biodiversity 9:328-334. ogana, f.n., osho, j.s., gorgoso-varela, j.j. (2015). comparison of beta, gamma and weibull distributions for characterizing tree diameter in oluwa forest reserve, ondosstate, nigeria. journal of natural sciences research, 5(4): 28-36. ogunjemite, b.g., agbelusi, e.a., afolayan, t.a., onadeko, s.a. (2006). “status survey of chimpanzee in the forest zone of southwestern nigeria”. acta zoological sinica, 52(4):1009–1014. ogunsesan, d., oyedepo, j., oates, j., adeofun, c.o., ikemeh, r., bergl, r. (2011). gis-supported survey of low-land rain forests in south-western nigeria proceedings of the environmental management conference, federal university of agriculture, abeokuta, nigeria wakawa et al. /journal of tropical forestry and environment vol. 8, no. 02 (2018) 69-81 81 onyekwelu, j.c., mosand, r., stimm, b. (2008). tree species diversity and soil status of primary and degraded tropical rainforest ecosystems in south-western nigeria. journal of tropical forest science, 20(3): 193–204. pimm, s.l., jenkins, c.n., abell, r., brooks, t.m., gittleman, j.l., joppa, l.n., raven, p.h., roberts, c.m., sexton, j.o. (2014). the biodiversity of species and their rates of extinction, distribution, and protection. science, 344(6187):1246752. rao, d.s., pragada, p.m., kumar, o.a. (2015). floristic composition and ecological assessment of tree species diversity in tropical forests of srikakulam and vizianagaram districts of andhra pradesh, india. int. j. fund. appl. sci., 4(1):23-29. thomas, s.c., baltzer, j.l. (2002). tropical forests. in: encyclopedia of life sciences. macmillan reference ltd, london, uk, nature publishing group (http://www.els.net/), pp 1-8. wittmann, f., zorzi, b.t., tizianel, f.a., urquiza, m.v., faria, r.r., sousa, n.m., módena, e.s., gamarra, r.m., rosa, a.l. (2008). tree species composition, structure, and aboveground wood biomass of a riparian forest of the lower miranda river, southern pantanal, brazil. folia geobot, 43:397–411. 404 not found muhammad et al. / journal of tropical forestry and environment vol. 11 no. 1 (2021) 49-60 effect of various agroforestry tree species on soil chemical properties of irrigated tree plantation of pakistan z.a. muhammad, m.a. javed*, g. yasin, i. ahmad department of forestry and range management, faculty of agriculture, university of agriculture, faisalabad, pakistan date received: 20-09-2019 date accepted: 18-06-2021 abstract pakistan is a forest deficient country and natural forests are seriously depleted due to overutilization and lack of proper conservation practices. agroforestry is being promoted to release the pressure on the natural forests as well as to increase farmlands utility and production. selecting tree species with the potential to increase soil fertility and offers less competition to the main crops is a fundamental problem. two exotic species acacia nilotica, eucalyptus camaldulensis, and an indigenous species, dalbergia sissoo were used to understand their role in changing the soil composition under an irrigated plantation environment. their effect was studied both at different soil layers and under and away from the canopy. all three species significantly affected the chemical composition of the soil. results revealed that the electrical conductivity, organic matter, n, p, k, and soil moisture were significantly higher under the canopy as compared to away from the canopy. most of the activity and significantly high minerals were found at 15–30 cm as compared to 0–15 cm soil strata. dalbergia sissoo is a deciduous tree and produced more leaf litter outperformed a. nilotica and e. camaldulensis. e. camaldulensis suppressed the understory growth of other plant species thus threatening local flora and fauna therefore should not be recommended for plantation on farmlands. d. sissoo a shade-intolerant shall be planted alone or mix with a. nilotica would be a preferred choice as they complement well due to sparse canopy of the latter. d. sissoo is mainly used for timber wood production whereas a. nilotica is used for fuelwood will help cope with the wood supply chain. it is therefore concluded that planting tree species improve the soil conditions positively however selection of the tree species should be done with caution. agroforestry has the potential to reduce the gap existing in timber wood production in pakistan. keywords: dalbergia sissoo, acacia nilotica, eucalptyus camaldulensis, soil fertility, agroforestry 1. introduction soil is the composite façade of physical, chemical, and biological processes which take place across spatial and temporal scales (robertson and gross, 1994). determinants of soil conditions in nature are parent material and typical weather (birkeland, 1984). in nature, forests are the most prolific bionetwork. for instance, soil fertility changes can be induced by tree species through the decomposition process which is influenced by microclimate and microbial communities in the forest floor (hobbie 1996; sariyildiz and anderson, 2003; mitchell et al., 2007). trees play a critical role in biogeochemical recycling (kelly et al. 1998). soil fertility in forested areas is improved mainly by adding plant litter. soil fertility under the tree cover is improved, which decreases soil erosion, adds soil organic matter, provides nutrients through effective litter recycling. due to urbanization, industrialization and population pressure on agricultural lands has increased many folds. these factors did not affect only environmental conditions but also affect agricultural production. soil fertility can be maintained by the tree litter during the decomposition process, provides organic matter and nutrients (koukoura et al. 2003). information’s regarding soil-plant interaction is an integral means to maintain 49 *correspondence: azurefromheavens@gmail.com © university of sri jayewardenepura 50 the sustainability of a productive system (koukoura et al. 2003). pakistan is a forest deficient country and natural forests have depleted at an alarming rate mainly due to overutilization and climate change. the agroforestry system is being promoted to release pressure on natural forests and conserve them. it is however extremely important that appropriate tree species are selected which not only produce useful biomass but also increase farmland fertility. this study was therefore conducted to determine the effect of three selected tree species i.e. acacia nilotica, eucalyptus camaldulensis exotic species, and dalbergia sissoo a native species, planted in an irrigated plantation, on the soil chemical composition. 2. materials and methods this research was carried out in chichawatni reserved forest located in punjab pakistan. chichawatni reserved forest is situated in district sahiwal along with lahore – karachi railway line between kassowal and dad fatiana railway stations punjab pakistan. the plantation is located in southern zone punjab pakistan between latitudes 30o-29´-32.91´´n and 30o-33´-45.84´´n and longitudes 72o-36´-00.25´´e and 72o-46´-48.65´´e at an elevation of 153.6 to 163.7m above sea level. the plantation is almost linear in form. it has a total area of 11531 acres. the parent material of the plantation consists of loamy soil. the local climate is generally hot often gets extremely hot during summers with mild winters. may, june, and july are the hottest months of the year when the temperatures soar to 40-50°c. while winter temperature ranges between 5-10°c. the average rainfall is 200 mm annually. chichawatni irrigated plantation originally was a typical dry tropical forest. the indigenous flora was dominated mainly by salvadora oleoides, tamarix articulate, prosopis cineraria, and capparisa phylla. recently other species such as acacia nilotica, eucalyptus camaldulensis, and dalbergia sissoo are also planted due to their fast growth and economic importance in the timber wood and fuelwood industry. figure 1. map of chichawatni plantation, located in chichawatni punjab, pakistan. 2.1 collection of soil samples soil samples were collected from under and away from the canopies of a. nilotica, d. sissoo, and e. camaldulensis. in the case of away canopy, soil samples were taken at a distance of 300 cm from the tree canopy at two different soil depths i.e. 0-15 cm and 15-30 cm with the help of a soil augar. soil samples were collected in cardinal directions and a composite sample was made by randomly taking four samples from each tree species to make one sample. five composite samples for each species were analyzed for soil organic matter, moisture content, nitrogen (n), phosphorous (p), potassium (k), sodium (na), fsulfur (s), chloride (cl), carbonate (car), bicarbonate (bicarb), electrical conductivity (ec), soil ph and soil moisture (sm) respectively. soil analysis was carried out by using standard protocols outlined by okalebo et al., (2002). analysis of variance (anova) was used to understand the effects of different tree species on soil chemistry. duncan multiple range test (dmrt) was carried for mean comparison by using the “agricolae” package incorporated in the r environment (r core team 2013). pearson’s correlation coefficient and biplot analysis erewere conducted to understand the association between different soil components. muhammad et al. / journal of tropical forestry and environment vol. 11 no. 1 (2021) 49-60 51 3. results the results indicated that three tree species had variable effects on the soil composition and it varied by the depth of the soil layer (table 1). the data were expressed as the mean for soil depth, sampling site, and type of species. 3.1 soil ph soil ph was significantly different at soil depth but a distance from canopy and species did not affect it significantly. soil ph was higher at 15 – 30 cm as compared to 0 – 15 cm. the ph of the soil was higher under the canopy of e. camaldulensis (table 1) however this difference was not significant. 3.2 soil electrical conductivity (ec) soil ec was significantly affected by soil depth and distance from canopy however all tree species did not show any difference in ec (table 1). soil ec measured under the canopy of the plantation was significantly higher than that away from the canopy. in 0 -15 cm soil depth ec was significantly higher than in 15-30 cm depth. 3.3 organic matter (om) total organic carbon is significantly affected by soil depth, distance from the canopy, and type of species (table 1). the concentrations of the organic matter recorded in a. nilotica, d. sissoo, and e. camaldulensis soils were 1.226, 1.125, and 1.085% respectively (table 1). the values of organic matter under d. sissoo were significantly higher than under a. nilotica and e. camaldulensis. a significant difference in organic matter was also observed between under and away from canopies of tree plantation and was higher under the canopy than that away from the canopy. depth effect was also significant and organic matter was high in 15-30 cm soil depth than that in 0-15 cm depth. 3.4 total soil nitrogen (n) the results showed that total soil n was significantly affected by soil depth, distance from the canopy, and type of species (table 1). significantly higher soil n concentration was observed under e. camaldulensis than that under a. nilotica and d. sissoo. values of soil n were significantly higher under the canopy of tree plantation in 0-15 cm depth than those away from a tree canopy in 15-30 cm depth. total nitrogen decreased by depth but increased under the tree canopy. 3.5 available phosphorus (p) soil depth, canopy distance, and type of species used had a significant effect on the available phosphorus (table 1). generally, high phosphorus was available under the canopy and at the deeper layer for both e. camaldulensis, a. nilotica, and less for d. sissoo. higher phosphorus at a depth of 015 cm was found under the canopy of e. camaldulensis and a minimum was observed under the canopy of d. sissoo. at 300 cm away from canopies of these tree species at the same depth significantly higher value was observed for a. nilotica and the lowest value was observed for d. sissoo. at 15-30 cm depth the maximum phosphorus was obtained for e. camaldulensis while minimum value was found for d. sissoo. 3.6 available potassium (k) total potassium is significantly affected by soil depth, distance from the canopy, and species type (table 1). the mean soil k concentration was significantly higher in e. camaldulensis and the lowest was observed for d. sissoo. significantly higher soil k concentration was observed under the canopy of tree plantation than that away from the canopy. likewise, 15-30 cm soil depth showed significantly higher soil k concentration as compared with that in 0-15 cm depth. 3.7 available sodium (na) total sodium (na) was significantly different for soil depth and distance from canopy however species did not aaffect sodium contents significantly (table 1). sodium concentration was high away from the canopy and in a deeper soil layer as compared to away from the canopy and top layer of the soil. the type of species did not affect sodium concentration significantly. 52 3.8 sulphur (s) and chloride (cl) soil depth had a significant effect on s and cl concentrations and distance from canopy species type did not affect them significantly (table 1). both were found to be in higher concentration at the deeper layer of soil as compared to the upper layer of soil for s and cl concentration in soils of a. nilotica, d. sissoo, and e. camaldulensis. soil s was higher in a. nilotica soil while cl was higher in e. camaldulensis soil. the soil under canopies of tree plantation showed comparatively higher soil s and cl concentrations than those away from the canopy. soil s and cl varied significantly in 0-15 and 15-30 cm soil depths and significantly higher concentrations of both s and cl were recorded in 15-30 cm soil depth. 3.9 carbonates (carb) and bicarbonates (bicarb) soil carbonates were significantly affected by soil depth and distance from the canopy (table 1). they were not affected by different tree species. similarly, a high concentration of bicarbonates was observed in the deeper layer of soil and it was affected by distance from canopy and type of species respectively. all species had a similar contribution of carbonates and bicarbonates in the soil. 3.10 soil moisture content moisture content determined in the soil under the canopy and at 300 cm away at two depths (015 cm and 15-30 cm) from the canopy of d. sissoo, a. nilotica, and e. camaldulensis in the chichawatni forest plantation is presented in table 1. moisture contents were significantly affected by distance from the canopy. under canopy had more moisture than away from the canopy. soil depth and tree species did not affect moisture contents significantly. e. camaldulensis had lower soil moisture followed by a. nilotica and d. sissoo respectively. 3.11 association among soil properties of tree plantation the pc1 and pc2 of pca explained 55.2% of the total variability (fig.1). associations among soil chemical properties of tree plantation under and away from canopies of d. sissoo, e. camaldulensis, and a. nilotica were explored with the angles between vectors. the angle between two vectors indicates a correlation between soil chemical components (table 2), obtuse and acute angles indicate a negative and positive association, respectively. the biplot showed that ec, ph, k, sm, n, and p were oriented toward the same plain these traits were positively correlated with each other as well as with root. the vectors of carbonates, na, cl, bicarbonates, s, and om were also oriented in the same direction in another plain showing positive correlations among these properties. table 2 shows that soil ph was significantly and positively correlated with soil ec, om, p, s, and bicarbonates. soil om also showed a significant positive correlation with soil ec, n, s, and bicarbonates. soil na and p showed a significant negative correlation with each other. as shown in figure 1., most soil parameters showed positive correlations among themselves, but fewer showed negative correlations, but these were not significant. 4. discussion woody plants have the potential to improve soil quality in different ways. soil physical, chemical, and biological quality areare greatly improved by tree species because of the addition of large amounts of leaf, root, twig, flowers, and fruits biomass to the soil (sarvade et al., 2019). overall, tree species affected the soil's chemical properties. changes in soil chemical properties under various tree species have been widely reported (russel et al., 2007; phillips and fahey, 2008). differences in soil chemical properties among tree species might be due to release of organic acids, quality or quantity of litter accumulated and the litter decomposition rate, and nutrients uptake or movement of nutrients from deeper soil to surface soil layers (jobbágy and jackson, 2004; russel et al., 2007). environmental conditions and the type of tree species also contribute to the variations in the soil's chemical properties (ayres, 2009). soil ph is a good indicator of soil microbial biomass and activity and plays an important role in the mineralization and availability of nitrogen (tian et al., 2013). in our study tree species did not show a significant change in soil ph, ec, na, s, cl, carb, bicarb, and sm. they however muhammad et al. / journal of tropical forestry and environment vol. 11 no. 1 (2021) 49-60 53 significantly affected om, n, p, and k respectively. d. sissoo showed high ec, om, carb, and sm contents. soil moisture is also significantly and positively correlated with om and ec. however, ph was comparatively low in d. sissoo soil and the highest was in e. camaldulensis. d. sissoo is deciduous species with a bigger canopy thus will have more litterfall as compared to a. nilotica and e. camaldulensis d. sissoo is mainly a subtropical species that vehave a low tolerance for salinity as compared to high tolerant e. camaldulensis with a very high salinity tolerance. e. camaldulensis is also notorious for allelopathic eeffects thus has the potential to change soil ph and high salt tolerance. marked suppression of vegetation was also observed under its canopy thus creating a major threat for local flora and fauna, reduced soil fertility, and increased soil erosion. lower ph may thus be attributed to increased accumulation of aboveground biomass, cation uptake, and synthesis of organic acids by different tree components (sarvade et al., 2014). ec was significantly affected by the distance from the canopy and soil depth. ec was high under the canopy due to the high accumulation of tree litter and on the upper soil strata. high ec was reported for the soil under acacia senegal as compared to open areas (githae et al., 2011). ec is significantly related to moisture content and other available minerals in the soil. this was particularly obse rved in d. sissoo where indigenous soils had low ec (<1.0) as compare d to newly established areas (> 1.0) in pakistan (asif et al., 2019). changes in ec of soil reflect drought conditions in a particular area which predisposes tree species to different pathogens. d. sissoo is particularly sensitive to high saline conditions as it is a subtropical species that require a high amount of freshwater. the relatively lower organic matter in e, camaldulensis soil is possibly due to the differences in the rates of plant litter decomposition under the a. nilotica and d. sissoo plantation (demessie et al., 2012). according to sharmsher et al. (2002), low organic matter (<1%) was found in 83% of the soil samples in e. camaldulensis plantation areas. species showed highly significant differences for n, p, and k. interestingly e. camaldulensis and a. nilotica showed the highest npk constituents followed by d. sissoo despite low leaf litter mass deposited. d. sissoo can utilize more k due to intermediary absorption by mycorrhizae as compared to other species. nitrogen concentration in soils is reflected in part by the rate of decomposition of the plant material (cao et al., 2010). low concentrations of nutrients are released due to slow decomposition of eucalypt that contains litter with low nutrient concentration (aweto and mokele, 2005; baber et al., 2006; cao et al., 2010; demessie et al., 2012) and coupled with the prevailing low soil ph, n mineralization from the e. camaldulensis litter would have been considerably slow. additionally, high soil nutrient uptake rates of the plant under eucalypts exhibited the total available n (tererai et al., 2014). similarly, phosphorus becomes inaccessible for plant use due to higher immobilization by eucalypts (aweto and mokele, 2005). in our study contrasting results of soil, phosphorus aswas observed as the soil p content was in sufficient range in e. camaldulensis soil. the addition of organic matter and reduction in soil moisture losses help to conserve soil moisture due to improved soil structure in tree-based systems. soil moisture concentration in each profile depth improves due to an increase in organic matter, reduction in evaporation, and erosion by the perennial tree species from natural forest and agroforestry systems (saha et al., 2004). the soil organic carbon is the key factor of improved soil properties (akhtar et al., 2018). the results of our study revealed that d. sissoo showed significantly higher organic carbon contents. ec, om, n, p, k, na, carb, and sm were significantly higher under tree canopy as compared to away from the canopy. this could be due to the accumulation and slow rate of decomposition of leaf litter under the canopy. similarly, most of the soil activity was observed between 15-30 cm soil layer as it is reflected with relatively high ph, om, p, k, na, s, cl, carb, bicarb, and sm respectively. noureen (2007) reported similar results on under canopy of calligonum polygonoides and acacia jacquemontii at 150 cm and 300 cm soil depth in the cholistan desert. similarly, karim et al. (2009) found a high percentage of moisture and other mineral contents under canopy soil as compared to an open area, while working on leptadenia pyrotechnica and capparis decidua. a high amount of available nitrogen (1.01-1.25 times) was observed as compared to an open area (0.83-0.94 times) due to the high rate of leaf shedding and root decay (cusak et al., 2009). d. sissoo and a. nilotica are leguminous crops preferred for agroforestry due to their positive effect on 54 soil fertility and productivity. an increased n and s concentrations were reported in other leguminous tree species of tropical savanna (abule et al., 2007, ceck et al., 2008). a high concentration of phosphorous under the canopy was also reported in the sites of low soil fertility and rainfall due to the enrichment of soil by woody plants (tredyte et al., 2007). potassium is the most abundant cation in the cells of non halophytic higher plants (maathuis et al., 1997). it is usually the most abundant of the major nutrient elements in the soil. the total k content of soils varies from <0.01% to about 4% and is commonly about 1% (wild, 1988). similar results were also quoted by imoro et al. (2014) while studying soil-plant improvement as influenced by planting voandzeia subterranean and arachis hypogea. arshad et al., (2008) described the higher contents of potassium under the canopy of aerva javanica, dipterygium glaucum, calligonum polygonoides, haloxylon salicornicum, and capparis decidua. carbonates were mainly affected by distance from the canopy and soil depth. chahouki et al. (2008) found high carbonate concentration away from the canopy as compared to other mineral contents that were higher in under the canopy soils in poshtkou rangelands of yazd province iran. the pca showed that soil organic carbon was positively correlated with nitrogen, phosphorus, potassium, and sulfur (figure 1). a major feature of soil organic matter is that it holds a relatively constant ratio of the different nutrients (kirkby et al., 2011). in the decomposition of the soil organic matter, these nutrients can be released into the soil although how much becomes available to plants depends on a range of factors. in the formation and then in the decomposition of soil organic matter, a flux of nutrients or recycling of nutrients is an outcome. phosphorus occurs in several pools in the soil and in many soils, the p from soil organic matter may be only one of these pools (shen et al., 2011). the mineralization of plants and soil organic matter can be a major source of p for plants (mclaughlin, 2011). 5. conclusion agroforestry is aggressively promoted in pakistan to conserve natural forests as they are depleting at an alarming rate and to cope with market demand for timber wood and fuelwood. different tree species have variable effects on the soil properties directly or indirectly therefore it is important to select tree species with increased biomass as well as which enhance the productivity of the farm soils. agroforestry tree plantation can be a good option for improving soil chemical properties and for achieving the sustainable use of soil. not only does soil improvement benefit soil and water conservation to avoid erosion losses but also helps to increase the productive capacity of the soil through improving soil chemical properties. this study aimed at assessing the effect of acacia nilotica, eucalyptus camaldulensis exotic species, and dalbergia sissoo an indigenous species on the soil chemistry. it was observed that trees have changed the chemical properties of the soils sampled under the selected tree stands. they had a similar effect on soil ph, ec, na, s, cl, carb, bicarb, and moisture contents. generally, d. sissoo and a. nilotica had improved soil chemistry as compared to e. camaldulensis. it was generally observed that e. camaldulensis suppressed understory growth of other plants resulting in low litter intensity and soil erosion. d. sissoo and a. nilotica are legumes and they have the potential to be established in the local agroforestry system due to their potential of increasing soil properties. moreover improved soil properties by some tree species could be associated with the nutrient uptake from the subsurface zones, recycling, biological nitrogen fixation, and solubilizing plant nutrients. therefore it is recommended that d. sissoo and a. nilotica shall be preferred over e. camaldulensis for agroforestry sectors. this is particularly important in a mixed planting scheme as e. camaldulensis suppresses understory vegetation and also due to its high water requirement as compared to other two speices. d. sissoo is shade intolerant thus shall be planted in a pure tree stand or mix with a. nilotica having sparse canopy and less shade effect on d. sissoo. muhammad et al. / journal of tropical forestry and environment vol. 11 no. 1 (2021) 49-60 55 references abule, e., snyman, h. and smit, g., 2007. rangeland evaluation in the middle awash valley of ethiopia: i. herbaceous vegetation cover. journal of arid environments, 70(2): 253-271. akhtar, k., wang, w., ren, g., khan, a., feng, y. and yang, g., 2018. changes in soil enzymes, soil properties, and maize crop productivity under wheat straw mulching in guanzhong, china. soil and tillage research, 182: 94-102. alemie t. c., 2009. the effect of eucalyptus on crop productivity, and soil properties in the koga watershed, western amhara region, ethiopia. unpublished m.sc. thesis, cornell university. angers, d.a. and caron, j., 1998. plant-induced changes in soil structure: processes and feedbacks. biogeochemistry, 42(1): 55-72. arévalo-gardini e., canto m., alegre j., loli o., julca a., baligar v., 2015. changes in soil physical and chemical properties in long term improved natural and traditional agroforestry management systems of cacao genotypes in peruvian amazon. plos one 10(7): 0132147 ariapour a. m., asgari, 2012. effect of soil properties on artemisia sieberi forage and growth. international conference on environment energy biotechnology, 33: 221-227. arshad, m., hassan, a., ashraf, m.y., noureen, s. and moazzam, m., 2008. edaphic factors and distribution of vegetation in the cholistan desert, pakistan. pak. j. bot, 40(5): 1923-1931. austin a.t., vivanco l., 2006. plant litter decomposition in a semi-arid ecosystem controlled by photodegradation. nature, 442: 555-558. aweto a. o., moleele n. m., 2005. impact of eucalyptus camaldulensis plantation on an alluvial soil in south eastern botswana. international journal of environmental studies 62(2): 163-170. ayres e., steltzer h., berg s., wallenstein m. d., simmons b.l., wall d. h., 2009. tree species traits influence soil physical, chemical, and biological properties in high elevation forests. plos one. 4: 5964. baber s., ahmad m., bhatti a., 2006. the effect of eucalyptus camaldulensis on soil properties and fertility. journal of agricultural and biological sciences 1(3): 47-50. belsky a. j., amundson r. g., duxberry r. m., riha s. j., ali a. r., mwonga s. m., 1989. the effects of trees on their physical, chemical and biological environments in a semi-arid savanna in kenya. journal of applied ecology 26: 1004-24. berg b. c., mcclaugherty, johansson m. b., 1997. chemical changes in decomposing litter can be systemized with respect to the litter’s initial chemical composition. reports from the departments in forest ecology and forest soils, swedish university of agricultural sciences, uppsala, sweden. rep.74: 1-85. birkeland, p.w., 1984.soils and geomorphology. oxford university press. blank r. r., demer j. d., 2004. effects of co2 enrichment on plant-soil relationships of lepidium latifolium. plant and soil, 262: 159-167. cao y., fu s., zou x., cao h., shao y., zhou l. 2010. soil microbial community composition under eucalyptus plantations of different age in subtropical china. european journal of soil biology, 46(2): 128-135. chahouki m. a., azarnivand z. h., jafari m., shafizadeh m., 2008. effects of soil characteristics on distribution of vegetation types in poshtkouh rangelands of yazd province (iran). journal of environmental research, 2: 413-417. cusack, d.f., chou, w.w., yang, w.h., harmon, m.e., silver, w.l. and lidet team, 2009. controls on long‐term root and leaf litter decomposition in neotropical forests. global change biology, 15(5): 1339-1355. demessie a., singh b. r., lal r., strand l. t., 2012. leaf litter fall and litter decomposition under eucalyptus and coniferous plantations in gambo district, southern ethiopia. journal of oncology agriculture. section b-soil and plant science, 62(5): 467-476. fu h., pei s., chen y., wan c., 2007. influence of shrubs on soil chemical properties in alxa desert steppe, china. usda forest service rmrs 47: 117-121. 56 hobbie s. e., eddy w. c., buyarski c.r., adair e.c., weisenhorn p., 2012. response of decomposing litter and its microbial community to multiple forms of nitrogen enrichment. ecological monographs (in press). hobbie s. e., 1996. temperature and plant species control over litter decomposition in alaskan tundra. ecological monographs, 66: 503-22. imoro z. a, adusei-boateng j., aikins t. k., 2014. comparison of soil fertility improvement ability of voandzeia subterranean and arachis hypogea. journal of agricultural research, 52(4): 489-498. jobbágy e. g., jackson r. b., 2004. the uplift of soil nutrients by plants: biogeochemical consequences across scales. ecology 85: 2380-2389. kamara c. s., haque i., 1992. faidherbia albida and its effects on ethiopian highland vertisols. agroforestry systems, 18(1): 17-29 karim b., azam m., hamid m., athar m., 2009. effect of the canopy cover on the organic and inorganic content of soil in cholistan desert. pakistan journal of botany, 41: 2387 kelly e. f., chadwick o. a., hilinski t. e., 1998. the effects of plants on mineral weathering. biogeochemistry, 42: 21-53. kirkby c. a., kirkegaard, richardson a.e., wade l. j., blanchard c., batten g., 2011. stable soil organic matter: a comparison of c:n:p:s ratios in australian and other world soils. geoderma, 163: 197-208. koukoura z., mamolos a. p., kalburtji k. l., 2003. decomposition of dominant plant species litter in a semi-arid grassland. applied soil ecology, 23: 13-23. maathuis f. j. m., audrey i. m., dale s., julian s. i.,1997. roles of higher plant k+ channels. the plant laboratory, department of biology, university of york. plant physiology, 114: 11411149. mclaughlin, m.j., mcbeath, t.m., smernik, r., stacey, s.p., ajiboye, b. and guppy, c., 2011. the chemical nature of p accumulation in agricultural soils—implications for fertiliser management and design: an australian perspective. plant and soil, 349(1): 69-87. mitchell, r.j., campbell, c.d., chapman, s.j., osler, g.h., vanbergen, a.j., ross, l.c., cameron, c.m. and cole, l., 2007. the cascading effects of birch on heather moorland: a test for the top‐ down control of an ecosystem engineer. journal of ecology, 95(3): 540-554. noureen s., 2007. effect of canopy cover of capparis decidua, acacia jaquemontii, and calligonum polygonoides on physiochemical properties of soil of cholistan desert. m. phil. thesis, islamia university bhawalpur: 100. odiwe a. i., muoghalu j. i., 2003. litter fall dynamics and forest floor litter as influenced by fire in a secondary lowland rain forest in nigeria. tropical ecology, 44: 241-248. phillips r. p., fahey t. j., 2008. the influence of soil fertility on rhizosphere effects in northern hardwood forest soils. soil science society of american journal, 72: 453-461 pragasan l. a., parthasarathy n., 2005. litter production in tropical dry evergreen forests of south india in relation to season, plant life forms and physiognomic groups. current science, 88: 1255-1263. robertson g. p., gross k. l., 1994. assessing the heterogeneity of below ground resources: quantifying pattern and scale. in: caldwell mm and pearcy rw (eds) exploitation of environmental heterogeneity by plants. academic press, new york: 237-253. russell, a.e., raich, j.w., fisher, r.f. and valverde-barrantes, o., 2007. tree species effects on soil properties in experimental plantations in tropical moist forest. soil science society of america journal, 71(4): 1389. saha r., mishra v. k., tomar j. m. s., 2004. soil water retention-transmission characteristics of various agro-forestry systems under hilly agriculture in meghalaya. indian journal of hill farming 17: 106-110. sariyildiz t., anderson j. m., 2003. interactions between litter quality, decomposition and soil fertility: a laboratory study. soil biology and biochemistry, 35: 391-9. muhammad et al. / journal of tropical forestry and environment vol. 11 no. 1 (2021) 49-60 57 sarvade s., 2014. agroforestry: refuge for biodiversity conservation, international journal of innovative research in science and engineering 2(5): 424-429 dev, i., ram, a., kumar, n., singh, r., kumar, d., uthappa, a.r., handa, a.k. and chaturvedi, o.p., 2019. agroforestry for climate resilience and rural livelihood. scientific publishers. sayer e. j., 2006. using experimental manipulation to assess the roles of leaf litter in the functioning of forest ecosystems. biological review, 81: 1-31. shamsher a., bhatti a. u., khan f., 2002. distribution of some selected soil properties under agroforestry and agricultural crops. pakistan journal of forestry, 52(1): 39-56. shen j., yuan l., zhang j., li h., bai z., chen x., zhang w., zhang f., 2011. phosphorus dynamics: from soil to plant. plant physiology, 156: 997-1005. tererai, f., 2012. the effects of invasive trees in riparian zones and implications for management and restoration: insights from eucalyptus invasions in south africa (doctoral dissertation, stellenbosch: stellenbosch university). tian y., takanashi k., toda h., haibara k/ ding f., 2013. ph and substrate regulation of nitrogen and carbon dynamics in forest soils in a karst region of the upper yangtze river basin, china, journal of forest research, 18: 228-237 treydte, a.c., heitkönig, i.m., prins, h.h. and ludwig, f., 2007. trees improve grass quality for herbivores in african savannas. perspectives in plant ecology, evolution and systematics, 8(4): 197-205. tripathi o. p., pandey h. n., tripathi r. s., 2009. litter production, decomposition and physicochemical properties of soil in 3 developed agroforestry systems of meghalaya, northeast india. african journal of plant science, 3 (8): 160-167. wild, a., 1988. potassium, sodium, calcium, magnesium, sulfur, silicon. russell's soil conditions and plant growth. eleventh edition: 743-779. xu, w., luo, g. and chen, x., 2006. soil properties under shrubs in arid area of oasis-desert transition belt. ying yong sheng tai xue bao =the journal of applied ecology, 17(4): 583-586. 58 table 1: summary of soil chemical parameters analysed for different tree species. fvalue distance depth species ph distance=3.692 n-s depth=10.256** species=0.179 n-s away =8.04±0.098 under=8.11±0.113 15-30 (cm)=8.133±0.081 (a) 0 -15 (cm)=8.022±0.108 (b) acacia nilotica=8.075±0.113 dalbergia sissoo=8.067±0.115 euclayptus camaldulensis= 8.092±0.108 ec distance=5.67* depth=32..07** species=1.54 n-s away =1.789±0.273 (b) under=1.975±0.378 (a) 15-30 (cm)=1.661±0.257 (b) 0-15 (cm)=2.104 ±0.256 (a) acacia nilotica=1.798±0.382 dalbergia sissoo=1.967±0.231 euclayptus camaldulensis=1.882±0.386 om distance =19.78** depth=75.89** species=9.38** away =1.084 ± 0.126 (b) under= 1.206 ± 0.194 (a) 15-30 (cm)=1.264±0.141 (a) 0-15 (cm)=1.026±0.108 (b) dalbergia sissoo=1.226±0.128(a) acacia nilotica=1.125±0.169(b) euclayptus camaldulensis=1.085±0.195 (b) n distance=38.722*** depth=6.63* species=3.978* away =0.650±0.097 (b) under=0.779±0.079 (a) 15-30 (cm)=0.688 ±0.089 (b) 0-15 (cm)=0.742 ±0.123 (a) acacia nilotica=0.721 ±0.106(a) dalbergia sissoo=0.677±0.128(a) euclayptus camaldulensis=0.748±0.085 (b) p distance=57.12** depth=8.88** species=14.46** away =5.67±0.878 (b) under=7.25±0.878 (a) 15-30 (cm)=6.77±1.14 (a) 0-15 (cm)=6.15±1.16 (b) euclayptus camaldulensis=6.95±1.10(a) acacia nilotica=6.76±0.961 (a) dalbergia sissoo=5.68±1.12(b) k distance=6.49* depth=22.44** species=6.41** away =126.11±20.02 (b) under=138.06±18.49 (a) 15-30 (cm)=143.06±14.69 (a) 0-15 (cm)=121.11±18.63 (b) euclayptus camaldulensis=140.6±14.13 (a) acacia nilotica=134.8±18.07(a) dalbergia sissoo=120.08±22.65(b) na distance=15.26** depth=5.957* species=0.179n-s away =1.12±0.322 (a) under=0.708±0.294 (b) 15-30 (cm)=1.043±0.337 (a) 0-15 (cm)=0.786±0.362 (b) acacia nilotica=0.942±0.403 dalbergia sissoo=0.922±0.261 euclayptus camaldulensis=0.879±0.445 s distance=1.812n-s depth=12.885** species=0.002 n-s away =6.539±0.917 under=6.939±0.94 15-30 (cm)=7.272±0.893 (a) 0-15 (cm)=6.205±0.645 (b) acacia nilotica=6.75±0.987 dalbergia sissoo=6.73±0.978 euclayptus camaldulensis=6.74±0.935 cl distance =0.946n-s depth=34.064** species=0.066n-s away =1.903±0.862 under=1.731±0.525 15-30 (cm)=2.33±0.516 (a) 0-15 (cm)=1.30±0.452 (b) acacia nilotica=1.783±0.753 dalbergia sissoo=1.801± 0.727 euclayptus camaldulensis=1.860±0.709 carb distance=93.04** depth=41.044** species=0.086n-s away =0.458±0.112 (a) under=0.233±0.082 (b) 15-30 (cm)=0.421±0.143 (a) 0-15 (cm)=0.271±0.119 (b) acacia nilotica=0.342±0.169 dalbergia sissoo=0.353±0.143 euclayptus camaldulensis = 0.343±0.149 bicarb distance=2.20n-s depth=13.75** species=0.038n-s away =2.217±0.805 under=2.214±0.699 15-30 (cm)=2.83±0.407 (a) 0 -15 (cm)=1.59±0.401 (b) acacia nilotica=2.28±0.730 dalbergia sissoo=2.21±0.770 euclayptus camaldulensis = 2.16±0.788 sm distance=6.774* depth=2.445n-s species=0.626n-s away =5.77±0.529 (b) under=6.30±0.632 (a) 15-30 (cm)=6.194±0.631 0-15 (cm)=5.877±0.613 acacia nilotica=5.944±0.466 dalbergia sissoo=6.195±0.604 euclayptus camaldulensis=5.967±0.809 muhammad et al. / journal of tropical forestry and environment vol. 11 no. 1 (2021) 49-60 59 table 2: association and effect of tree species, soil depth and distance from canopy on various soil chemical components in an irrigated plantation. ph ec om n p k na s cl carb bicarb sm ph 1 0.45** 0.58** 0.28 0.51** 0.54** 0.03 0.6** 0.17 0 0.41** 0.16 ec 0.45** 1 0.70** 0.23 0.29 0.43** 0.12 0.61** 0.46** 0.05 0.56** 0.36* om 0.58** 0.70** 1 0.36 0.28 0.35 0.03 0.5** 0.27 0.03 0.5** 0.41** n 0.28 0.23 0.36 1 0.63** 0.37 -0.25 0.34** 0.05 -0.34* 0.22 0.28 p 0.51** 0.29 0.28 0.63** 1 0.62** -0.39* 0.42** 0.04 -0.37* 0.2 0.21 k 0.54** 0.43** 0.35 0.37 0.62** 1 -0.02 0.46** 0.34* 0.07 0.45* 0.05 na 0.03 0.12 0.03 -0.25 -0.39* -0.02 1 0.09 0.4** 0.64** 0.32 0.01 s 0.6** 0.61** 0.5** 0.34** 0.42** 0.46** 0.09 1 0.38* 0.1 0.72** 0.02 cl 0.17 0.46** 0.27 0.05 0.04 0.34* 0.4** 0.38* 1 0.51** 0.76** 0.12 carb 0 0.05 0.03 -0.34* -0.37* 0.07 0.64** 0.1 0.51** 1 0.36* -0.18 bicarb 0.41** 0.56** 0.5** 0.22 0.2 0.45* 0.32 0.72** 0.76** 0.36* 1 0.03 sm 0.16 0.36* 0.41** 0.28 0.21 0.05 0.01 0.02 0.12 -0.18 0.03 1 60 figure 2. biplot showing association between different soil chemical components sampled at different soil depths, under and away canopy of three tree species. ratnayake /journal of tropical forestry and environment vol. 8, no. 02 (2018) 1-12 1 feature article paleoenvironmental reconstructions using organic source indicators: a summary of examples from sri lanka a.s. ratnayake faculty of science and technology, uva wellassa university, badulla, sri lanka abstract the qualitative and quantitative analysis of sedimentary organic matter (i.e., the residue of past biota) provides integrated histories of marine and continental past life and paleoenvironmental /paleoclimatic changes. organic geochemical investigations are possible by combining (i) bulk properties such as elemental compositions, stable isotope ratios, and rock-eval pyrolysis data, and (ii) biomarker molecular compositions such as n-alkanes, sterol, and polycyclic aromatic hydrocarbons compositions. the analytical approaches described in this overview illustrate the published examples of lacustrine and marine organic geochemical studies in sri lanka. in summary, the jurassic andigama and tabbowa basins provide different sources of organic matter, followed by availability of nutrient for algal growth and the amount of land runoff to the basins. rock-eval analysis of the cretaceous to paleogene sedimentary rocks in the offshore mannar basin reveal the presence of gas-prone land-plant organic matter mainly and minor oil-prone algal organic matter. the amounts and types of organic matter variations in bolgoda lake sediments indicate changes in holocene sea-level, coastal geomorphology, and continental climates during the last 7,000 years. in future directions, applications of novel organic geochemical proxies and understanding of original biologically synthesized materials in tropics would improve interpretations of paleoenvironmental changes. besides, local and regional paleoclimatic proxy and model studies would refine future paleoenvironmental reconstructions in sri lanka. keywords: organic carbon, c/n ratios, biomarkers, n-alkanes, sri lanka 1. introduction photosynthesis is the fundamental process for mass production of organic matter (om) since the precambrian. terrestrial higher plants have contributed to primary production since the devonian. phytoplankton, zooplankton, and higher plants can be presently recognized as the main contributors to om in sediments. the om content can vary in sediments from less than 0.1% to 4%, and depends on aquatic primary productivity (autochthonous), secondary accumulation of terrestrial om (allochthonous), and preservation against microbial decomposition in an oxygen-deficient environment (berner, 1982; meyers, 1997; sampei et al., 1997a). the primary productivity in the aquatic environment is principally controlled by light, temperature, and nutrient such as phosphate and nitrate. further, om-rich sediments are present in lagoons, estuaries, and continental slopes followed by high primary productivity and/or deposition of land-derived terrestrial plant materials (meyers and ishiwatari, 1993; sampei et al., 1997b). the fine-grained sediments enhance the preservation of coated om in sediments by limiting the access of dissolved oxygen (berner, 1984; berner and raiswell, 1984; sampei et al., 1997a). *correspondence: as_ratnayake@uwu.ac.lk tel: +94 766052194 issn 2235-9370 print/issn 2235-9362 online © university of sri jayewardenepura 2 sedimentary om is a mixture of lipids, carbohydrates, proteins, and other biochemical compounds such as lignin in higher plants (sampei and matsumoto 2001; meyers, 2003). microbial activities begin in recently deposited sediments, mainly near the water-sediment interface. this diagenesis process leads transforming biopolymers into geopolymers/geochemical fossils in sediments synthesised by plants/animals with minor changes (sun and wakeham, 1998; marynowski and wyszomirski, 2008; chen et al., 2017). sedimentary basins are diverse, and the sources and alterations of om are geographically and temporally variable. therefore, a variety of elemental, isotopic, and molecular indicators/proxiesin sedimentary om could reconstruct past environmental changes in the watershed (e.g., silliman et al., 1996; versteegh et al., 2004; suzuki et al., 2010). 2. organic geochemical proxy 2.1 bulk indicators total organic carbon (toc) is a major proxy to determine om richness in sediments (meyers and ishiwatari, 1993; meyers, 1997; hossain et al., 2009). toc concentrations depend on several factors such as om production, accumulation, and preservation, occasionally in a complicated manner. toc (wt. %) values can decline due to clastic dilution under a high rate of sedimentation (e.g., berner, 1982; ibach, 1982; sampei et al., 1997b). in addition, toc concentrations commonly decrease with the increase of sediment grain size (e.g., silliman et al., 1996; meyers, 1997). c/n ratios are the popular organic geochemical proxy to differentiate sedimentary om of algae and terrestrial plants (silliman et al., 1996; meyers, 1997; sampei and matsumoto, 2001). algae consist of protein-rich substance, whereas terrestrial plants consist of cellulose-rich substance. algae, thus, record c/n ratios of 4 to 10, and c/n ratios of terrestrial plants are greater than 20 (meyers and ishiwatari, 1993; meyers, 2003). c/n ratios can be partially enhanced during the early diagenesis due to selective decomposition of proteinaceous components. alternatively, c/n ratios can be partially diminished in marine and fine-grained sediments due to ammonia absorption (müller, 1977; hossain et al., 2009). grain-size distribution of sediments can also impact the c/n ratios. for example, coarse-grained sediments normally contain a larger proportion of terrestrial plant debris than fine-grained sediments (silliman et al., 1996; meyers, 2003). carbon isotope ratios can distinguish om sources using paleoproductivity evidence. for example, δ13c values of c3 calvin pathway and c4 hatch-slack pathway plants are -27% and -14%, respectively. in addition, δ13c values of marine om range from -20 to -22% (bender, 1971; huang et al., 2001). the grain size distribution of sediments does not influence the δ13c values, and thus, the δ13c value is a useful om type indicator with temporal changes indepositional conditions (meyers, 1997). rock-eval pyrolysis analysis is now frequently used in paleoenvironmental studies to identify kerogen types and their diagenetic alteration routes, based on modified van krevelen-type diagrams (tissot and welte, 1978; tissot et al., 1980, 1987). as discussed in 3.2, three main kerogen types could be identified from the pyrolysis results of hydrogen index (hi) and oxygen index (oi). type i kerogen is primarily derived from algal om in an anaerobic environment, especially lacustrine. type ii kerogen is typically derived from marine om in reducing to suboxic environments, and type iii kerogen is predominantly derived from higher plants (tissot et al. 1980; jiang et al., 2015; mashhadi et al., 2015). 2.2 molecular (biomarkers) indicators molecular compounds such as n-alkanes and sterol are particularly valuable to paleoenvironmental reconstructions. these compounds, named as “biological markers” or “biomarkers”, are comparatively less sensitive to biodegradation than other oms. consequently, aliphatic hydrocarbon components such as n-alkanes area vital aspect of paleoenvironmental reconstruction due to its reasonably specific biological origins (eglinton and hamilton, 1967; ficken et al., 2000; hoffmann et al., 2013; carr et al., 2014). ratnayake /journal of tropical forestry and environment vol. 8, no. 02 (2018) 1-12 3 the sources of oms are distinguishable mainly by the chain lengths of their molecular suites. the presence of short-chain n-alkanes (i.e., c17, c19, and c21) and long-chain n-alkanes (i.e., c27, c29, and c31) indicate algal contributions and land-plant epicuticular waxes, respectively (eglinton and hamilton, 1967; zhou et al., 2005; castańeda et al., 2009). the n-alkane distributions of submerged and floating macrophytes commonly maximise at c23 and c25 (ficken et al., 2000; nott et al., 2000). the contributions of land-derived om typically comprise higher amounts of n-alkanes compared to aquatic algae (cranwell, 1990; meyers and ishiwatari, 1993). however, n-alkane distributions in sediments can help to reconstruct paleovegetational records in the watershed. for example, c31 and c27/c29 are indicators for grasses and trees dominate watersheds, respectively (nott et al., 2000; zhou et al., 2005; castańeda et al., 2009). sterol compositions is another approach to distinguish aquatic and terrestrial organic matters in sediments. in addition, the progressive changes of c27, c28, and c29 sterols in a ternary plot indicate the changes of aquatic and terrestrial organic sources (huang and meinschein, 1979; meyers, 1997). this illustration is usually applied to reconstruct sources of om in sediments deposited at temporal scale, as discussed under section 3.1. polycyclic aromatic hydrocarbons (pahs) are formed by diagenesis changes and lowand hightemperature combustion. therefore, pahs can indicate both paleoecological and paleoenvironmental characteristics (jiang et al., 1998; yunker and macdonald, 2003; han et al., 2014). pahs distribution in recent sediments can act as an indication for anthropogenic activities in the watershed (e.g., meyers, 2003; yunker and macdonald, 2003). 3. organic geochemical evidence for paleoenvironmental changes in sri lanka 3.1 comparison of the jurassic om contributions to the andigama and tabbowa basins sri lanka records two jurassic sedimentary basins known as the andigama and tabbowa basins along the northwest onshore margin (figure 1). figure 1: simplified geological map of sri lanka shows the important study sites discussed in this overview (modified after ratnayake et al., 2017a). 4 organic geochemical studies have been concentrated on andigama mudstone and tabbowa finegrained sedimentary rocks (ratnayake and sampei, 2005). the n-alkanes distribution of the andigama basin suggests the deposition of terrestrial higher plant dominated om with some amount of plankton/algae oms (figure 2). figure 2: comparison of representative n-alkane distribution in the andigama and tabbowa basins (modified after ratnayake and sampei, 2015). the middle chain length homologs of the andigama mudstones can be interpreted as the development of lacustrine to swamp environments (e.g., meyers and ishiwatari, 1993; ficken et al., 2000; nott et al., 2000). however, the n-alkanes distribution suggests the deposition of plankton/algae dominated oms in the tabbowa basin (figure 2). similarly, the ternary diagram of c27-c28-c29 steranes indicates the depositions of terrestrial oms in andigama basin and algae oms in tabbowa basin, respectively (figure 3). ratnayake /journal of tropical forestry and environment vol. 8, no. 02 (2018) 1-12 5 figure 3: comparison of om sources and depositional environments of the andigama and tabbowa basins using the ternary diagram of c27-c28-c29steranes (modified after huang and meinschein, 1979; ratnayake and sampei, 2015). figure 4 illustrates the distribution of pahs and alkylated phenanthrenes in the andigama mudstones. several organic sources indicating biomarkers are observed in pahs fraction. for example, retene and simonellite can be derived from gymnosperm om sources such as conifer resins (jiang et al., 1998; yunker and macdonald, 2003; yunker et al., 2011). cadalene is also a terrestrial land plants indicator from both angiosperm and gymnosperm (otto et al., 2002; simoneit, 2005; han et al., 2014). however, no angiosperm plants were recorded in the eastern gondwanaland during the jurassic (e.g., aarssen et al., 2000; friis et al., 2006). therefore, in this study, cadalene can also be identified as an indicator for gymnosperm plant resins. furthermore, perylene helps to reconstruct paleoenvironmental characteristics such as deposition of wood-degrading fungi oms under the temperate humid climatic conditions (aizenshtat, 1973; suzuki et al., 2010; marynowski et al., 2013). moreover, the detected fluoranthene, pyrene, benzo[a]anthracene, chrysene/triphenylene, benzofluoranthene, benzo[e]pyrene, benzo[a]pyrene, indeno[cd]pyrene, and benzo[ghi]perylene pahs (figure 4) indicate mediumtemperature ground fire to high-temperature crown fire in the watershed (jiang et al., 1998; denis et al., 2012). methylated aromatic isomers can be used as organic source indicators (killops, 1991; budzinski et al., 1995). for example, 1-methylphenanthreneand 9-methylphenanthrene (figure 4) is mainly derived from terrestrial om-rich sediments (type-iii kerogen) (budzinski et al., 1995; hossain et al., 2013). therefore, 1-methylphenanthrene and 9-methylphenanthrenemayhave originated from coniferous gymnosperm in andigama sediments. the 1, 7-dimethylphenanthrene (figure 4) can also be originated from gymnosperm resin (armstroff et al., 2006; fabiańska et al., 2013). 6 figure 4: the representative (a) polycyclic aromatic hydrocarbons (pahs) and (b) alkylated phenanthrenes distributions in the andigama mudstones (modified after ratnayake and sampei, 2015). p-phenanthrene, fla-fluoranthene, py-pyrene, baan-benzo[a]anthracene, chry + tpnchrysene/ triphenylene, bflas-benzofluoranthene, bepy-benzo[e]pyrene, bapy-benzo[a]pyrene, peryperylene, inpy-indeno[cd]pyrene, bghip-benzo[ghi]perylene, cad-cadalene,sim:simonellite, ret-retene, mpmethylphenanthrenes and dmp-dimethylphenanthrenes. 3.2 cretaceous to paleogene depositional environments in the offshore mannar basin the mannar basin is an offshore sedimentary basin between southeast of india and sri lanka (figure 1). the mannar basin covers around 45,000 km2 in sri lankan jurisdiction and records organic carbon-rich sediments from the jurassic to recent in age. rock-eval pyrolysis analysis applies to the petroleum industry and the paleoenvironmental studies, as discussed in 2.1. in this method, types of kerogen and thermal maturity of sediments can be mainly interpreted using standard reference diagrams (e.g., tissot and welte, 1978; tissot et al., 1980, 1987). the modified van krevelen diagram (i.e., hydrogen index (hi) versus oxygen index (oi) assists in identifying the dominant kerogen type of om (tissot and welte 1978; tissot et al. 1980, 1987; jiang et al., 2015; mashhadi et al., 2015). figure 5 depicts that both cretaceous to paleogene sediments in the mannar basin consist of mixed type iii (mainly) and type ii kerogens. therefore, geochemical characteristics of the mannar basin samples have a high potential for gas hydrocarbon generation. ratnayake /journal of tropical forestry and environment vol. 8, no. 02 (2018) 1-12 7 figure 5: the modified van krevelen diagram shows kerogen types in the offshore mannar basin (modified after ratnayake et al., 2018a). 3.3 holocene paleoenvironmental changes in the coastal bolgoda lake toc content and c/n ratio of bolgoda lake surface sediments range from 1.31 to 6.89% and 10.4 to 15.8, respectively (ratnayake et al., 2017b, and 2018b). therefore, it suggests the deposition of algae om dominant sapropelic sediments with some terrestrial contribution. also, development of sapropelic condition depends on om preservation under oxygen-poor to anoxic conditions. sulfur and organic carbon relationship (c/s ratio) can identify oxic/anoxicdepositional conditions (berner, 1984; berner and raiswell, 1984; sampei et al., 1997a). the low c/s ratios (2.8±0.8) of bolgoda lake surface sediments suggest oxygen-poor stagnant bottom environment (ratnayake et al., 2017b, 2018b). the core sediments of bolgoda lake can divide in to two sections as the lower sedimentary succession (from ca. 7.0 calky b.p. to ca. 2.5 calky b.p.) and the upper sedimentary succession (after ca. 2.5 calky b.p.) based on sedimentary facies, geomorphological observations and chronological and geochemical data (ratnayake et al., 2017b). figure 6 illustrates that toc values have depleted in the lower sedimentary (1%-4%) compared to the upper sedimentary succession (3%-30%), respectively. this major environmental change, thus, indicates nutrient enrichment after ca. 2.5 calky b.p. (figure 6).it was followed by variations in om concentration/type and depositional conditions (ratnayake et al., 2017b). therefore, this major environmental change is mainly controlled by coastal geomorphological evolution from a bay of paleo river to a semi-closed and oxygen-depleted brackish lagoon due to middle holocene sea-level changes (ratnayake, 2016; ratnayake et al., 2017b). the reconstruction of paleo-mangrove vegetation using specific molecular indicators assists in identifying sea-level changes in tropics and sub-tropical regions (e.g., behling et al., 2001; versteegh et al., 2004). for example, taraxerone can be mainly derived from mangrove vegetation (versteegh et al., 2004; koch et al., 2005, 2011). therefore, based on the distribution of taraxerone biomarker, ratnayake et al. (2017b) concluded the initial seawater invasion occurred ca. 7.0 calky b.p. along the west coast of sri lanka. 8 figure 6: total organic carbon (toc) variations of core 1 and core 2 in bolgoda lake show the major environmental change (modified after ratnayake et al., 2017b). the n-alkanes distribution can reconstruct not only organic sources but also paleoclimate (cranwell, 1990; ficken et al., 2000; hoffmann et al., 2013). according to sachse et al. (2006) and carr et al. (2014), broadleaf tree leaves contain longer chain n-alkanes in warm or dry regions compared to in cold or wet areas. therefore, the distribution of n-c29/n-call and n-c37/n-call ratios in bolgoda lake sediments (figure 7) indicates a gradual transition of paleoclimate from colder or wetter (middle holocene) to warmer or drier climate (late-holocene). figure 7: the distribution of n-c29/n-call and n-c37/n-call ratios in bolgoda lake sediments (modified after ratnayake et al., 2017b). ratnayake /journal of tropical forestry and environment vol. 8, no. 02 (2018) 1-12 9 4. future perspectives in future research, several additional developments are necessary to quantify paleoproductivity of algae, terrestrial contribution/watershed vegetation, and to understand the transportation process. it is significant to identify novel biomarker information in tropics that can act as a proxy for reconstruction of paleoenvironment/paleoclimate. in addition, early diagenesis incorporation of microorganism in tropical sediments should be investigated in future research. at present, only limited studies have been conducted to reconstruct the paleoenvironmental changes in sri lanka. the future investigations should specifically focus on underexplored southeast and northeast coastal regions, and finally, it is crucial to link paleoenvironmentalproxy studies with multidisciplinary numerical/model interpretations. acknowledgment the author acknowledge yoshikazu sampei, shimane university, japan for providing laboratory facilities of the original research work, nalin prasanna ratnayake, university of moratuwa, sri lanka, director general saliya wickramasuriya of petroleum resources development secretariat (prds), sri lanka, chaminda kularathne and chaturanga senevirathne for supporting to obtain samples/field guides for the original research works. references aarssen, b.g.k.v., alexander, r., kagi, r.i. (2000). higher plant biomarkers reflected palaeovegetation changes during jurassic times. geochimicaet cosmochimica acta, 64, 1417-1424. aizenshtat, z. (1973). perylene and its geochemical significance. geochimicaet cosmochimica acta, 37, 559-567. armstroff, a., wilkes, h., schwarzbauer, j., littke, r., horsfield, b. (2006). aromatic hydrocarbon biomarkers in terrestrial organic matter of devonian to permian age. palaeogeography, palaeoclimatology, palaeoecology, 240, 253-274. behling, h., cohen, m.c.l., lara, r.j. (2001). studies on holocene mangrove ecosystem dynamics of the braganca peninsula in north-eastern para, brazil. palaeogeography, palaeoclimatology, palaeoecology, 167, 225-242. bender (1971).variations in the 13c/12c ratios of plants in relation to the pathway of photosynthetic carbon dioxide fixation. phytochemistry, 10, 1239-1244. berner, r.a. (1982). burial of organic carbon and pyrite sulfur in the modern ocean: its geochemical and environmental significance. american journal of science, 282, 451-473. berner, r.a. (1984). sedimentary pyrite formation: an update. geochimicaet cosmochimica acta, 48, 605-615. berner, r.a., raiswell, r. (1984).c/s method for distinguishing freshwater from marine sedimentary rocks.geology, 12, 365-368. budzinski, h., garrigues, p.h., connan, j., devillers, j., domine, d., radke, m., oudin, j.l., (1995). alkylated phenanthrene distributions as maturity and origin indicators in crude oils and rock extracts.geochimicaet cosmochimica acta, 59, 2043-2056. carr, a.s., boom, a., grimes, h.l., chase, b.m., meadows, m.e., harris, a., (2014). leaf wax n-alkane distributions in arid zone south african flora: environmental controls, chemotaxonomy and palaeoecological implications. organic geochemistry, 67, 72-84. castańeda, i.s., werne, j.p., johnson, t.c., filley, t.r., (2009). late quaternary vegetation history of southeast africa: the molecular isotopic record from lake malawi. palaeogeography, palaeoclimatology, palaeoecology, 275, 100-112. chen, x., andersen, t.j., morono, y., inagaki, f., jørgensen, b.b., lever, m.a., (2017). bioturbation as a key driver behind the dominance of bacteria over archaea in near-surface sediment. scientific reports, 7, 2400. cranwell, p.a., (1990). paleolimnological studies using sequential lipid extraction from recent lacustrine sediment: recognition of source organisms from biomarkers. hydrobiologia, 214, 293-303. 10 denis, e.h., toney, j.l., tarozo, r., anderson, r.s., roach, l.d., huang, y., (2012). polycyclic aromatic hydrocarbons (pahs) in lake sediments record historic fire events: validation using hplc-fluorescence detection. organic geochemistry, 45, 7-17. eglinton, g., hamilton, r.j., 1967. leaf epicuticular waxes. science, 156, 1322-1335. fabiańska, m.j., stanislaw, r., ćmiel, s.r., misz-kennan, m., (2013). biomarkers and aromatic hydrocarbons in bituminous coals of upper silesian coal basin: example from 405 coal seam of the zaleskie beds (poland). international journal of coal geology, 107, 96-111. ficken, k.j., li, b., swain, d.l., eglinton, g., (2000). an n-alkane proxy for the sediment input of submerged/ floating freshwater aquatic macrophytes. organic geochemistry, 31, 745-749. friis, e.m., pedersen, k.r., crane, p.r., (2006). cretaceous angiosperm flowers: innovation and evolution in plant reproduction. palaeogeography, palaeoclimatology, palaeoecology, 232, 251293. han e.m., sampei, y., roser, b., (2014). upper eocene coal and coaly shale in the central myanmar basin: origin of organic matter and the effect of weathering. geochemical journal, 48, 1-17. hoffmann, b., kahmen, a., cernusak, l.a., arndt, s.k., sachse, d., (2013). abundance and distribution of leaf wax n-alkanes in leaves of acacia and eucalyptus trees along a strong humidity gradient in northern australia. organic geochemistry, 62, 62-67. hossain, h.m.z., sampei, y., roser, b.p., (2009). characterization of organic matter and depositional environment of tertiary mudstones from the sylhet basin, bangladesh. organic geochemistry, 40, 743-754. hossain, h.m.z., sampei, y., roser, b.p., (2013). polycyclic aromatic hydrocarbons (pahs) in late eocene to early pleistocene mudstones of the sylhet succession, ne bengal basin, bangladesh: implications for source and paleoclimate conditions during himalayan uplift. organic geochemistry, 56, 25-39. huang, w.y., meinschein, w.g., (1979). sterols as ecological indicators. geochimicaet cosmochimica acta, 43, 739-745. huang, y., street-perrott, f.a., metcalfe, s.e., brenner, m., moreland, m., freeman, k.h., (2001). climate change as the dominant control on glacial-interglacial variations in c3 and c4 plant abundance. science, 293, 1647-1651. ibach, l.e.j., (1982). relationship between sedimentation rate and total organic carbon content in ancient marine sediments. american association of petroleum geologists bulletin, 66, 170-188. jiang, c., alexander, r., kagi, r.i., murray, a.p., (1998). polycyclic aromatic hydrocarbons in ancient sediments and their relationships to palaeoclimate. organic geochemistry, 29, 1721-1735. jiang, h., pang, x., shi, h., yu, q., cao, z., yu, r., chen, d., long, z., jiang, f., (2015). source rock characteristics and hydrocarbon expulsion potential of the middle eocene wenchang formation in the huizhou depression, pearl river mouth basin, south china sea. marine and petroleum geology, 67, 635-652. killops, s.d., (1991). novel aromatic hydrocarbons of probable bacterial origin in a jurassic lacustrine sequence. organic geochemistry, 17, 25-36. koch, b.p., filho, p.w.m.s., behling, h., cohen, m.c.l., kattner, g., rullkötter, j., scholz-böttcher, b., lara, r.j., (2011). triterpenols in mangrove sediments as a proxy for organic matter derived from the red mangrove (rhizophora mangle). organic geochemistry, 42, 62-73. koch, b.p., harder, j., lara, r.j., kattner, g., (2005). the effect of selective microbial degradation on the composition of mangrove derived pentacyclictriterpenols in surface sediments. organic geochemistry, 36, 273-285. marynowski, l., smolarek, j., bechtel, a., philippe, m., kurkiewicz, s., simoneit, b.r.t., (2013). perylene as an indicator of conifer fossil wood degradation by wood-degrading fungi. organic geochemistry, 59, 143-151. marynowski, l., wyszomirski, p., (2008). organic geochemical evidences of early-diageneticoxidation of the terrestrial organic matter during the triassic arid and semi-arid climatic conditions. applied geochemistry, 23, 2612-2618. ratnayake /journal of tropical forestry and environment vol. 8, no. 02 (2018) 1-12 11 mashhadi, z.s., rabbani, a.r., kamali, m.r., (2015). geochemical characteristics and hydrocarbon generation modeling of the kazhdumi (early cretaceous), gurpi (late cretaceous) and pabdeh (paleogene) formations, iranian sector of the persian gulf. marine and petroleum geology, 66, 978-997. meyers, p.a., (1997). organic geochemical proxies of paleooceanographic, paleolimnologic, and paleoclimatic processes. organic geochemistry, 27, 213-250. meyers, p.a., (2003). applications of organic geochemistry to paleolimnological reconstructions: a summary of examples from the laurentian great lakes. organic geochemistry, 34, 261-289. meyers, p.a., ishiwatari, r., (1993). lacustrine organic geochemistry: an overview of indicators of organic matter sources and diagenesis in lake sediments. organic geochemistry, 20, 867-900. müller, p.j., 1977. c/n ratios in pacific deep-sea sediments: effect of inorganic ammonium and organic nitrogen compounds sorbed by clays. geochimicaetcosmochimicaacta 41, 765-776. nott, c.j., xie, s., avsejs, l.a., maddy, d., chambers, f.m., evershed, r.p., (2000). n-alkane distributions in ombrotrophic mires as indicators of vegetation change related to climatic variation. organic geochemistry, 31, 231-235. otto, a., simoneit, b.r.t., wilde, v., kunzmann, l., püttmann, w., (2002). terpenoid composition of three fossil resins from cretaceous and tertiary conifers. review of palaeobotany and palynology, 120, 203-215. ratnayake, a.s., (2016). evolution of coastal landforms during the holocene epoch along the west and southeast coasts of sri lanka. interdisciplinary environmental review, 17, 60-69. ratnayake, a.s., kularathne, c.w., sampei, y., (2018)a. assessment of hydrocarbon generation potential and thermal maturity of the offshore mannar basin, sri lanka. the journal of petroleum exploration and production technology, 8, 641-654. ratnayake, a.s., ratnayake, n.p., sampei, y., vijitha, a.v.p., jayamali, s.d., (2018)b. seasonal and tidal influence for water quality changes in coastal bolgoda lake system, sri lanka. journal of coastal conservation, 22, 1191-1199. ratnayake, a.s., sampei, y., (2015). characterization of organic matter and depositional environment of the jurassic small sedimentary basins exposed in the northwest onshore area of sri lanka. researches in organic geochemistry, 31, 15-28. ratnayake, a.s., sampei, y., kularathne, c.w., (2017) a. current status of hydrocarbon exploration in sri lanka. international journal of oil, gas and coal technology, 16, 377-389. ratnayake, a.s., sampei, y., ratnayake, n.p., roser, b.p., (2017) b. middle to late holocene environmental changes in the depositional system of the tropical brackish bolgoda lake, coastal southwest sri lanka. palaeogeography palaeoclimatology palaeoecology, 465, 122-137. sachse, d., radke, j., gleixner, g., (2006). δd values of individual n-alkanes from terrestrial plants along a climatic gradient–implications for the sedimentary biomarker record. organic geochemistry, 37, 469-483. sampei, y., matsumoto, e., (2001). c/n ratios in a sediment core from nakaumi lagoon, southwest, japan: usefulness as an organic source indicator. geochemical journal, 35, 189-205. sampei, y., matsumoto, e., kamei, t., tokuoka, t., (1997) a. sulfur and organic carbon relationship in sediments from coastal brackish lakes in the shimane peninsula district, southwest, japan. geochemical journal, 31, 245-262. sampei, y., matsumoto, e., tokuoka, t., inoue, d., (1997) b. changes in accumulation rate of organic carbon during the last 8000 years in sediments of nakaumi lagoon, japan. marine chemistry, 58, 39-50. silliman, j.e., meyers, p.a., bourbonniere, r.a., (1996). records of postglacial organic matter delivery and burial in sediments of lake ontario. organic geochemistry, 24, 463-472. simoneit, b.r.t., (2005). a review of current applications of mass spectrometry for biomarker/molecular tracer elucidation. mass spectrometry reviews, 24, 719-765. sun, m.y., wakeham, s.g., (1998). a study of oxic/anoxic effects on degradation of sterols at the 12 simulated sediment-water interface of coastal sediments. organic geochemistry, 28, 773-784. suzuki, n., yessalina, s., kikuchi, t., (2010). probable fungal origin of perylene in late cretaceous to paleogene terrestrial sedimentary rocks of northeastern japan as indicated from stable carbon isotopes. organic geochemistry, 41, 234-241. tissot, b., demaison, g., masson, p., delteil, j.r., combaz, a., (1980). paleoenvironment and petroleum potential of middle cretaceous black shales in atlantic basins. the american association of petroleum geologists bulletin, 64, 2051-2063. tissot, b.p., pelet, r., ungerer, ph., (1987). thermal history of sedimentary basins, maturation indices, and kinetics of oil and gas generation. the american association of petroleum geologists bulletin, 71, 1445-1466. tissot, b.p., welte, d.h., (1978). petroleum formation and occurrences. springer-verlag, new york: 3201. versteegh, g.j.m., schefuß, e., dupont, l., marret, f., damste, j.s.s., jansen, j.h.f., (2004). taraxerol and rhizophora pollen as proxies for tracking past mangrove ecosystems. geochimicaet cosmochimica acta, 68, 411-422. yunker, m.b., lachmuth, c.l., cretney, w.j., fowler, b.r., dangerfield, n., white, l., ross, p.s., (2011). biota : sediments partitioning of aluminium smelter related pahs and pulp mill related diterpenes by intertidal clams at kitimat, british columbia. marine environmental research, 72, 105-126. yunker, m.b., macdonald, r.w., (2003). alkane and pah depositional history, sources and fluxes in sediments from the fraser river basin and strait of georgia, canada. organic geochemistry, 34, 14291454. zhou, w., xie, s., meyers, p.a., zheng, y., (2005). reconstruction of late glacial and holocene climate evolution in southern china from geolipids and pollen in the dingnan peat sequence. organic geochemistry, 36, 1272-1284. microsoft word 8 karunarathna fernando & karunaratne /journal of tropical forestry and environment vol. 3, no. 01 (2013) 64-69 64 mella (olax zeylanica) leaves as an eco-friendly repellent for storage insect pest management h. s. d. fernando * and m. m. s. c. karunaratne department of zoology, university of sri jayewardenepura, sri lanka date received: 10-11-2012 date accepted: 12-03-2013 abstract among the cereals, rice is the most important staple food supplying energy requirements for most of the worlds’ population. however during storage a loss of about 10-20% rice grains occurs due to stored grain pests. repellents are considered as the best source of protection against insect attack upon stored products as they have potential for the exclusion of stored product pests from grain, and thereby preventing insect feeding and oviposition on food materials. various plant materials have been utilized effectively through time as safe and ecofriendly insect pest control measures due to their repellent activity. the aim of the present study was to investigate the potential of powdered leaves and leaf extracts of olax zeylanica as repellents against the rice weevil, sitophilus oryzae. all the experiments were carried out under laboratory conditions using 1-7 day old unsexed adults. four different doses (1.0g, 3.0g, 5.0g and 7.0g).of powdered leaves were tested for fumigant repellency in a dual-choice bio-assay apparatus. repellent action of leaf extracts was evaluated by means of an area preference test using methanol, ethanol and nhexane as solvents. repellent effect of powdered leaves against the adult rice weevils was found to be significantly high (p< 0.05) at all doses. the highest repellent effect was produced by 7.0g of leaf powder resulting in repellency of 97%, while the lowest dose (1.0g) also elicited more than 50% repellency in weevils indicating a very strong repellent action of the powdered leaves. in comparison, methanol extract of leaves produced the highest repellent effect (96%) on weevils whereas n-hexane extract elicited the lowest. nevertheless, at higher concentrations all three extracts produced more or less significantly similar repellent effect on the weevils. the findings of the present study suggest that certain active materials of olax zeylanica leaves have potential to act as a grain protectant and may be exploited for the control of sitophilus oryzae in rice storage in an environment-friendly way. keywords: olax zeylanica, sitophilus oryzae, repellent effect, stored rice 1. introduction the practice of using plant derivatives or botanical insecticides in agriculture dates back at least two millennia in ancient china, egypt, greece and india (isman, 2006). in many developing countries, utilization of locally available plant materials to protect stored products against pest damage is common practice in traditional farm storage systems (akob & ewete, 2007). as martin & gopalakrishnan (2005) state these plant materials were not only used as insecticides but also as insect repellents and insect antifeedants. *correspondence: sacdinu@gmail.com tel: +94 11 2804515 issn 2235-9370 print / issn 2235-9362 online ©2013 university of sri jayewardenepura fernando & karunaratne /journal of tropical forestry and environment vol. 3, no. 01 (2013) 67-72 65 plants have developed effective morphological and chemical defense mechanisms that ensure survival under rough environmental conditions and in the presence of natural enemies. these chemical defenses either may produce mortality of the insect by acting as an insecticide or may affect common biochemical and physiological functions and act as repellents, antifeedants or oviposition inhibitors. excessive use of conventional pesticides disrupts natural pest control mechanisms and enhances development of pesticide resistant insect strains. in addition, they may have lethal effects on non-target organisms and may pose toxicity to consumers (dubey et al., 2008; white & leesch, 1995). compared to conventional pesticides, crude or formulated botanical pesticides tend to have broadspectrum activity, and are relatively specific in their mode of action, easy to process by the small scale farmers and would be safe for the higher organisms (viglianco et al., 2008). according to prakash et al. (2008) these pesticides do not contribute to resistance development or pest resurgence, nor do they cause negative effects on non-target organisms and also they do not affect food quality. deterioration of the quality and quantity of the food materials is a major problem in storage systems. stored rice seeds and milled rice is prone to be infested by rice weevils, sitophilus oryzae l. (coleoptera: curculionidae), causing heavy economic losses. adult weevils feed on rice grains and lay eggs within the grain surface and the larvae develop inside the grain thus feeding preferentially on the germ of the grain. because both larvae and adults feed on germ of the grain, the grain is completely damaged beyond any use. prevention of food losses during postharvest storage without creating environmental problems is therefore, of paramount economic importance. hence, the primary objective of this investigation was to evaluate the repellent activity of leaves of olax zeylanica against adult sitophilus oryzae as identification of effective as well as locally available botanicals will provide a sustainable alternative in controlling storage insect pests. 2. materials and methods 2.1 host material whole and un-infested white raw rice was used for bioassays and as rearing media to prevent contamination of laboratory cultures. unsexed, 1-7 days old adult rice weevils were used for bioassays. all bioassays were carried out under ambient laboratory conditions of 29±2 0 c and 84 ± 2% rh. 2.2 preparation of plant powder freshly collected leaves of olax zeylanica were washed thoroughly under running tap water to remove any contaminants. these were then shade dried until the water was evaporated. the dried leaves were ground to fine powder using a domestic electric grinder (multinational®, 2102, india). 2.3 preparation of plant extracts hundred grams of freshly ground leaf powder was mixed with 350ml of solvent and kept for 48 hours while stirring from time to time. three solvents, methanol (99.85%), ethanol (96%) and nhexane (95%) were used for the bioassays. after 48 hours each of the resulting crude extract was filtered using filtermann® (125mm) filter papers. the filtered extract was then concentrated using a vacuum rotary evaporator (microsil, india) at 65 0 c until the extract was reduced approximately to 60ml and was considered as the stock solution. a series (1ml, 3ml, 5ml, 7ml, and 10ml) of this stock solution was dissolved in 10ml of the appropriate solvent and five dilutions (t1, t2, t3 t4 and t5) each were made. 2.4 fumigation repellency assay for plant powders the bioassay apparatus for fumigation repellency test consisted of two plastic containers separated by a perforated lid (figure1). powdered leaves were introduced into the bottom container (height10cm, fernando & karunaratne /journal of tropical forestry and environment vol. 3, no. 01 (2013) 64-69 66 diameter 6cm) and the upper container consisted of 50g of rice. the upper part of this container was perforated with a thick needle to allow the insects escape from the container if they were repelled by the fumes emanating from the powdered leaves. the bioassay apparatus was placed inside a larger container (height 25cm, diameter 10cm) to trap the weevils that escaped through the holes in the test container. the mouth of the larger container was covered with a piece of polythene which has tiny holes in it to allow ventilation. test insects were then introduced into the container consisting rice, and the holes on the container was covered with a sticky tape for 10 minutes to let the introduced insects settle down inside. a similar bio-apparatus without leaf powder was used as the control. number of escaped insects was recorded after half an hour and one hour of introduction of weevils. four doses (1.0g, 3.0g, 5.0g and 7.0g) of powdered leaves and the control were assayed against the weevils. this test was replicated five times. figure1: bioassay apparatus for the fumigation repellency test 2.5 repellency assay for leaf extracts repellency of adult weevils for leaf extracts was tested using an area preference test. the test area consisted of a filtermann® (125mm) paper disc that was cut into two parts. one part of the filter paper was treated with 1ml of the prepared extract as uniformly as possible and the other part was treated with 1ml of the solvent which was considered as the control. both the treated half and the control half of the filter paper were then air dried to evaporate the solvent completely. a full disc was carefully re-made by attaching the treated part to the control part with adhesive tape and then placing it in a petri-dish. before the onset of the experiment, glycerin was applied on to the side walls of the petri-dish to prevent the weevils moving to the top. 10g of rice seeds were distributed uniformly on the remade full disc as an attractant for the weevils to stay on the paper. ten unsexed adult weevils were then released on to the centre of each filter paper disc and a lid was placed over the petri dish. thirty minutes after the introduction, the adult weevils present on each half of the filter paper was counted. ten replicates were made for five concentrations of three solvent-plant extracts of o. zeylanica. 2.6 analysis of data statistical package “minitab 14” was used for all the statistical analyses. data obtained were subjected to one way analysis of variance (anova). tukey’s multiple comparison test (p<0.05) was used to separate mean values of the experiments. perforated container with 50g rice and 30 insects container with plant powders fernando & karunaratne /journal of tropical forestry and environment vol. 3, no. 01 (2013) 67-72 67 3. results and discussion according to figure 2, it is clear that the volatiles of leaf powders of o. zeylanica played a significant role on rice weevils by repelling them away from the treated chamber to the outer container. one hour after introduction of weevils, the highest repellency (88.67%) was observed for 7g of leaf powder. figure 2: mean percentage repellency of s. oryzae to different doses of plant powders *mean repellency ± sd for ten replicates (n= 100) the repellency rate of methanol, ethanol and nhexane extracts at different doses on s. oryzae is presented in table 1. the findings of this experiment revealed that the rate of repellency increased with the increase of dose level. for this bioassay, solvents with different polarity were selected in order to extract differently polarized compounds from o. zeylanica leaves into the solvents table1: repellency of s. oryzae to different concentrations of three plant solvent extracts in an area preference test. means followed by the same letters are not significantly different according to tukey’s test at p<0.05 treatment % repellency± sd methanol ethanol nhexane t1 75.0 ± 0.85 ab 68.0 ± 0.79 b 57.0 ± 1.16 b t2 78.0 ± 1.03 ab 85.0 ± 1.43 a 67.0 ± 0.95 b t3 93.0 ± 0.95 a 86.0 ± 0.84 a 68.0 ± 0.79 b t4 94.0 ± 0.84 a 86.0 ± 0.96 a 80.0 ± 1.33 ab t5 96.0 ± 0.52 a 94.0 ± 0.69 a 83.0 ± 1.06 a probability p< 0.05 p < 0.05 p < 0.05 fernando & karunaratne /journal of tropical forestry and environment vol. 3, no. 01 (2013) 64-69 68 among all the concentrations and solvents tested, methanol extract was found to be the one with the strongest repellent effect on s. oryzae with percentage repellency of 96% at the highest concentration followed by ethanol extract (94%). hexane extracts elicited significantly lower repellency rate when compared with ethanol and methanol extracts nevertheless at higher concentrations repellent effect of all three extracts were not significantly different (p< 0.05) from each other in spite of their different polarity levels. this suggests that the repellent activity of the leaf extracts may be due to a combination of different types of allelochemicals. regardless of the solvent used, all three extracts at all concentrations produced considerably high repellent activity in weevils signifying that even lower amounts of the leaf material could be used effectively as a repellent against the rice weevil. the present study reveals that the repellent effect of o. zeylanica on s. oryzae was directly attributable to the volatiles emitted from the leaves as the weevils were not in direct contact with the leaf powder or extracts. moreover, previous studies conducted on fumigant toxic effect of o. zeylanica leaf volatiles on s. oryzae have shown 100% mortality in weevils even at small doses (fernando & karunaratne, 2012). these observations verify the fact that some volatile constituents of o. zeylanica leaves elicit both repellent and insecticidal effects. in view of these results it is quite apparent that o. zeylanica leaves can be used as an effective fumigation agent in controlling rice weevil infestations. in recent years, many research workers have given greater attention to the control of stored grain pests especially s. oryzae using leaf and seed powders, extracts and essential oils of various plant species. mishra et al (2012) demonstrated that essential oils of eucalyptus globulus and ocimum basilicum leaves were effective in repelling rice weevils. khani et al (2011) evaluated the toxicity and repellency of crude extracts of piper nigrum and jatropha curcas on s. oryzae adults and stated that both species of plant extracts could be applied against rice weevil effectively. leaf powder of mentha viridis has been observed to be highly effective as a repellent to s. oryzae (gunaratne & karunaratne (2009). the findings of the present study indicate that active compounds present in the powders and extracts of o. zeylanica leaves may play a role in the biological activity against adult s. oryzae. these compounds may independently or jointly contribute to cause repellent action against s. oryzae. these results also suggest that leaves of this plant have potential to provide rice grain protection and may be exploited for rice weevil control in storage in an environmental friendly way. however, further studies are needed to isolate and identify the active chemical compounds responsible for this activity and to examine the effect of powdered leaves and leaf extracts of o. zeylanica against a wider-range of storage insect pests. references akob, c. a., & ewete, f. k. (2007). the efficacy of ashes of four locally used plant materials against sitophilus zeamais (coleoptera: curculionidae) in cameroon. international journal of insect science, 27(1), 21-26. dubey, n. k., srivastava, b. and kumar, a. (2008). current status of plant products as botanical pesticides in storage pest management. journal of biopesticides, 1(2):182 – 186. fernando and karunaratne, m. m. s. c. (2012). ethnobotanicals for storage insect pest management: effect of powdered leaves of olax zeylanica in suppressing infestations of rice weevil sitophilus oryzae (l.) (coleoptera:curculionidae), journal of tropical forestry and environment vol. 2, no. 01, 20-25 gunaratne, t. v. n. m. and karunaratne, m. m. s. c. (2009). laboratory evaluation of some sri lankan plants as post-harvest grain protectants for the control of rice weevil sitophilus oryzae. vidyodaya journal of science, 14 (2) : fernando & karunaratne /journal of tropical forestry and environment vol. 3, no. 01 (2013) 67-72 69 isman, m.b. (2006). botanical insecticides, deterrents, and repellents in modern agriculture and an increasingly regulated world. annual review of entomology, 51, 45–66. khani, m., awang, r. m., omar, d., rahmani, m., & rezazadeh, s. (2011). tropical medicinal plant extracts against rice weevil, sitophilus oryzae l. journal of medicinal plants research, 5(2), 259-265. martin, r. j. and gopalakrishnan, s. (2005). insecticidal activity of aerial parts of synedrella nodiflora gaertn (compositae) on spodoptera litura (fab.). journal of central european agriculture, 6(3), 223-228. mishra, b. b.,tripathi, s. p. and tripathi, c. p. m. (2012). repellent effect of leaves essential oils from eucalyptus globulus (mirtaceae) and ocimum basilicum (lamiaceae) against two major stored grain insect pests of coleopterans. nature and science, 10(2):50-54. prakash, a. rao, j. and nandagopal, v. (2008). future of botanical pesticides in rice, wheat, pulses and vegetables pest management. journal of biopesticides, 1(2):154 169 viglianco, a. i., novo, r. j., cragnolini, c. i., nassetta, m., & cavallo, a. (2008). antifeedant and repellent effects of extracts of three plants from córdoba (argentina) against sitophilus oryzae (l.) (coleoptera: curculionidae). bioassay, 3(4), 1-6. white, n.d.g.and leesch, j.g. (1995). chemical control. in: integrated management of insects in stored products (eds. b. subramanyam and d.w. hagstrum). marcel dekker, new york, pp. 287-330. kalubowila et al/ journal of tropical forestry and environment vol. 10 no. 01 (2020) 63-74 63 floristic survey of meethirigala forest reserve in gampaha district j.d. kalubowila 1 *, b.m.p. singhakumara 1 and r.a.m.p.m. rajathewa 2 1 department of forestry and environmental science, university of sri jayewardenepura, nugegoda, sri lanka 2 environmental consultants, education and rehabilitation organization (ecero), gampaha, sri lanka date received: 05-05-2020 date accepted: 26-06-2020 abstract meethirigala forest reserve consists of approximately 384 ha. it is the largest forest reserve in gampaha district managed by the forest department. it has different topographic positions such as ridges, midslopes and valley areas close to the kelani river. the present study was conducted to enumerate plant species found in all three topographic positions of the reserve. plots were demarcated purposively to sample woody perennials equal or greater than 5 cm dbh (diameter at breast height) in 18 plots (5×100 m, rectangular shape). seedlings greater than 1 m tall were sampled in 18 plots (5×5 m). shannon diversity indices were calculated to compare dominance of particular species in different topographic positions. a total of 360 individuals of woody perennials belonging to 73 species in ridge, 368 individuals of woody perennials belonging to 100 species in midslope and 272 individuals of woody perennials belonging to 69 species in valley were recorded. and 132, 123 and 100 individuals of seedlings were enumerated in ridge, midslope and valley respectively. in ridge 58 generas, 28 families, in midslope 83 generas, 35 families and, in valley 68 generas, 29 families were observed. 28 species were found in all three different altitudes of the reserve. forest species in study sites gave a total of 138 plant species belonging to 113 tree species, 11 climber species, 14 shrub species, 109 generas and 46 families. of this total 138 species, 34 (25%) species are endemic to sri lanka. highest endemism was recorded in the ridge (41.6%). stratification of the ridge showed a very similar pattern to a dipterocarp forest type. highest diversity was recorded in midslope (1.7290) and lowest recorded in ridge (1.5626) of the forest. 18 threatened species were observed (3-endangered and 15-vulnerable species). as a conclusion, meethirigala forest reserve can be considered as an important refuge for wet zone forest species. keywords: forest reserve, ridge, midslope, valley, species 1. introduction sri lanka together with the western ghats in southern india, is a one of the currently recognised, thirty five global hotspots for biological diversity (ariyarathne et al., 2017). these 35 hotspots define regions where 43% of vertebrates (including 60% of threatened mammals and birds), and 80% of all threatened amphibians (mittermeier et al., 2011; williams et al., 2011) survive within habitat covering just 17.3% of the earth’s surface. to qualify as a hotspot, a region must meet two criteria: it must contain at least 1,500 species (>0.5 percent of the world’s total) of vascular plants as endemics; and it must have lost at least 70% of its original habitat due to the impacts of human activities (green et al., 2009). studies on floristic composition is essential for the management of an area for habitat and ecosystem conservation. __________________________________________________________________________________________________________________________________________________________________________________________________________________ *correspondence: jdkalubowila@gmail.com tel: +94 717523070 ©university of sri jayewardenepura doi: https://doi.org/10.31357/jtfe.v10i1.4689 64 the present land form of sri lanka is the result of millions of years of weathering by rain and wind, as well as movement of the earth’s crust. the topography of sri lanka is remarkably varied for itsmall area, with coastal plains, lowland hills and a mountainous interior. this variation is reflected in the complexity of the island’s diversity of natural plant communities and crops (ashton et al., 1997). sri lanka’s forest cover is diminishing rapidly and now stands at less than 20% of its pre-colonial extent (figure 1) (mattsson et al., 2012; perera, 2001). legg and jewell (1995), noted additionally that 23% of the island’s forest cover consisted of ‘sparse’ (secondary) forest. most recently, perera and tsuchiya (2009), in their study of forest cover in south-eastern sri lanka (an extent of 11,800 km 2 including the yala national park complex and its surroundings), found that in the two decades spanning 1987-2006, forest cover halved (40.2% to 20.6%) while homestead vegetation doubled (16.4% to 30.1%) and mixed scrub-dominant vegetation increased by almost 20% (34.3% to 41.4%). figure 1. the decline of closed-canopy forest cover in sri lanka since 1950 (mattsson et al., 2012). gampaha district, forest cover occupies approximately 0.56% of the total land area in western province. it includes 428 ha (0.31%) of natural forest and 345 ha (0.25%) of plantations (bambaradeniya, 2008). as per the national red list of sri lanka (2012), this country has 3,154 species with 894 endemic species of angiosperms. those belongs to 185 families. declines in populations, together with declines in areas of occupancy, extents of occurrence and/or the quality of habitat, determine the conservation status of the vast majority of the endemic sri lankan species that have been assessed as threatened as part of the iucn’s red listing process (iucn, 2001). currently sri lanka has over 1,385 flowering threatened plant species among the 3,154 species assessed so far (the national red list, 2012). information on the threatened status of species in other plant groups are lacking. family anacardiaceae has 46.7% of endemics was considered as nationally threatened during the national red listing in 2012. the conservation of sri lanka’s flora has received much less attention than its fauna, the data in dassanayake and fosberg (1980-1991), that as many as 61 endemic flowering-plant species (including 23 trees) had not been collected in the preceding 50 years, having passed almost unnoticed. the objectives of this study, to examine floristic composition and diversity of meethirigala forest reserve and to record endemic and threatened plants of the meethirigala forest reserve. kalubowila et al/ journal of tropical forestry and environment vol. 10 no. 01 (2020) 63-74 65 2. methodology 2.1 site selection study site was selected based on the reconnaissance survey. selected forest is the largest forest reserve in gampaha district managed by the forest department, sri lanka. reason for the selection of this site was according to the available information this contain comparatively high amount of natural vegetation (figure 2). meethirigala forest reserve was declared by the forest department on 4th august 1973. this forest patch consists of approximately 384 ha according to the survey department. a public bus route runs across this reserve dividing the forest into two large portions. the kelani river flows along the southern boundary of the gampaha district and number of small tributaries flow within the meethirigala forest reserve finally draining into the kelani river. meethirigala forest patch is surrounded by home gardens, public roads, paddy fields and rubber plantations. within this reserve there is a buddhist monastery that has been there since 1968. the monastery is occupied by the hermitage buddhist monks and therefore not much human activities take place and hence with no illegal human encroachments. this forest reserve has been utilised by the villagers in many ways to collect fuel wood, medicines, chena cultivation etc. in the meethirigala forest reserve, some areas can be recognised as disturbed while rest of the reserve is relatively undisturbed. 2.2 general geography and climate topographically, the area is divided into plains and highlands with an elevation ranging from 30450 m, below 30m altitude is considered as the plains, with little undulating lands. the elevation ranging from 150-450 m of the meethirigala and kiridiwela are considered as highlands. the average rainfall of 2,000-2,500 mm and mean annual temperature is 32 o c with little fluctuations annually (suraweera et al., 1999). 2.3 data collection size of the plots were pre-determined based on reconnaissance survey. 5×100 m plots were laid out at each sampling location to sample woody perennials that equal or exceed 5 cm dbh. 5×5 m plots were laid out at each sampling location to sample seedlings greater than 1 m in height. eighteen sample plots for both woody perennials and seedlings were sampled. size of the plots were different for woody perennials (5×100 m) and seedlings (5×5 m). sample plots distributed in disturbed and undisturbed sites are shown in table 1. plots were demarcated purposively to sample the vegetation. plot is 100 m long and 5 m wide. it was measured along the center line using a nylon rope. dbh and height of each plant species that equal or exceed 5 cm dbh was recorded. dbh was recorded using dbh tape and height was visually estimated. plants that have some special identification characters were identified with the help of field experts. the national red list 2012 of sri lanka was used to find out the endemic species and no. 22 of 2009 flora and fauna protection ordinance (amendment) was used to find out protected status of the recorded species. table 1: distribution of sample plots. tree species diversity index by relating the total number of species to the total number of individuals in the sample. shannon wiener diversity index was used for comparative purposes (dong and ji, 2011). no of plots disturbed undisturbed valley midslope ridge valley midslope ridge 18 (5×100 m) 1 2 0 5 4 6 18 (5×5 m) 1 2 0 5 4 6 66 (2) (3) (1) diversity: h / = -σ pi×log (pi) where: pi=proportional abundance pi=no. of individuals of a particular species/no. of all individuals of all species evenness: ⁄ where: h / max=log s s=no. of species found in the stand estimated profile diagrams were prepared for the three topographic positions. for this purpose, only vegetation up to 5 m on either side of the line was recorded. seedlings of greater than 1 meter in height the extent and location of these groups of seedlings was noted rather than each individual. the names of all tree and shrub species was recorded. total height was recorded to the nearest meter. fig ure 2. forest interior of meethirigala forest reserve. 3. results clear stratification was observed in forest ridge. trees with average diameter of 15.7 cm (six 5×100 m plots) in ridge. canopy layer occurs 35-40 m in height. emergent layer was seen over the canopy layer. below the canopy is lower story of medium sized trees principally comprised, between 2530 m in height (sub-canopy layer). dipterocarpus zeylanicus was found as most common species in ridge, other than that artocarpus nobilis, chaetocarpus castanocarpus, shorea sp, myristica dactyloides, garcinia quaesita, gyrinops walla, chrysophyllum roxburghii and bridelia mooni. d. zeylanicus was 9.8% from the total number of species found in ridge and major tree species contribute to form canopy layer. aporusa lanceolate, mallotus rhamnifolius, dillenia retusa and g. walla was found as most common seedlings in ridge. average dbh of trees in midslope was 16 cm (six 5×100 m plots). kalubowila et al/ journal of tropical forestry and environment vol. 10 no. 01 (2020) 63-74 67 the height of trees was low in midslope than ridge, but the dbh of trees was higher than the ridge. most common tree species were d. zeylanicus, a. nobilis, bridelia retusa, and vitex altissima. seedlings found in midslope were ixora coccinea, osbeckia aspera, pagiantha dichotoma, gaertnera vaginans, symplocos cochinchinensis, a. nobilis and acronychia pedunculata. average dbh was 12.4 cm in valley (six 5×100 m plots). valley has trees with lowest height and dbh compared to ridge and midslope. the most common species were, s. cochinchinensis, caryota urens, macaranga peltata, humboldtia laurifolia, syzygium caryophyllatum and d. retusa. figure 3. diameter-class distribution of tree species. a total of 1,012 individuals (dbh≥5 cm) were recorded in eighteen 5×100 m plots. a total of 355 individuals (seedlings>1 m tall) were recorded in eighteen 5×5 m plots. 368, 360 and 272 individuals were recorded in 5×100 m plots and 132, 123 and 100 individuals were recorded in 5×5 m. it was found that there were 138 species in meethirigala forest reserve and out of that 34 species are endemic. endemic percentage of identified species was 25%. ninety-seven species were indigenous, and seven species were exotic and three species were identified up to generic level. list (botanical name, family, life form, taxonomic status and conservation status) of plants found in the study area have been given in appendix (1). total 138 species distributed in three different altitudes of the reserve as follows. only in ridge-13, only in midslope-28, only in valley-18, ridge and midslope-26, ridge and valley-4, midslope and valley-18, all three positions-29 species were observed. eighteen threatened species (appendix 2) were found and out of that semicarpus marginata, salacia oblonga and zanthoxylum rhesta was found as endangered species. highest endemism (41.6%) was found in ridge and lowest (26.3%) found in valley. diameter class distribution of selected tree species demonstrated various patterns of distributions. low dbh classes have higher species density distribution than the higher dbh classes (figure 3). 3.1 estimated profile diagrams diverse vertical structure of forest provided a variety of environmental conditions from strata in the canopy to the forest floor shown in figure 4-6. diagrams clearly shows that different plant communities in three different altitudes of the forest. 68 figure 4. vertical distribution of trees in ridge. figure 5. vertical distribution of trees in mid-slope. kalubowila et al/ journal of tropical forestry and environment vol. 10 no. 01 (2020) 63-74 69 figure 6. vertical distribution of trees in valley. 4. discussion stratification was clear in ridge of the forest. it has been recognised that the forest canopy has a complex structure that is significant for environmental interactions, regeneration, growth, and biotic habitat. not only is the structure variously complex, but also there are many ways to conceptualise that complexity. yet the persistent theme when considering the structure of canopies continues to be that of stratification. oversized trees reaching heights of more than 45m tall was found in the emergent layer. together, the top branches and leaves from emergent layer trees form a mushroom shape above the thick canopy layer below. the major tree species contribute to form canopy layer, d. zeylanicus and it was the dominant tree species in ridge area. understory was quite dark. because of the lack of sunlight that is able to penetrate into the forest floor. ground was covered with leaf litter and few ground layer species was seen. in this study dipterocarpaceae is the most dominat family followed by annonaceae, euphorbiaceae, moraceae and clusiaceae in ridge. apocynaceae is the most dominant family in midslope followed by moraceae, dipterocarpaceae, euphorbiaceae and anacardiaceae. altitude of meeethirigala fr is affected the dominace of species while the aspect of vegetation affected only the distribution of the species. natural regeneration is the process by which woodlands are restocked by trees that develop from seeds that fall and germinate in situ. important factor in natural regeneration is the size of gaps created in forest. good regeneration of primary forest species takes place in those small gaps created by naturally dying trees within the primary forest. secondary species rarely invade those naturally formed gaps to compete successfully within the primary species (gunatilleke and gunatilleke, 1984). natural regeneration has been occurred in ridge, because seedlings of woody perennials has been observed. seedlings of d. zeylanicus and g. walla was observed. in the present study 34 endemic species was recorded, out of that 29 tree species, 4 shrub species and 1 climber species. endemism represents a unique step in the process of evolution, which could be sustained only in the locality concerned depending on the environmental quality, habitat is very much 70 important. there was a large population of zeuxine regia which is an endemic species belongs to the family orchidaceae (figure 7). it is an endangered medicinal plant. it has not been recorded earlier in the gampaha district. during the ecological study in kanneliya mab reserve and peak wilderness sanctuary it was observed that the most common families associated with z. regia were ebanaceae, anacardiaceae and dipterocarpacea, and species associated with z. regia were, anysophyllea cinnamoides, mangifera indica, shumacheria castaneifolia, gnidia gaertn and s. cochinchinensis (hewage, 2011). in the present study it was observed that a. cinnamoides and s. cochinchinensis associated with z. regia. the reason that certain species grow together in a particular environment will usually be, because they have similar requirements for existence in terms of environmental factors. species diversity of lowland was slightly higher than sub montane and upper montane forests. lowland diversity is higher and upper montane has lower diversity in peak wilderness sanctuary (singhakumara, 1995). floristic similarity between locations is closely related to the geographical distances of them. these slight differences of the diversity may be due to the elevation changes. alstonia macrophylla was observed in three topographic positions. it shows some invasive characteristic inside the forest. the source of introduction is mainly from wet and intermediate forests and affected to the secondary forests. invasive species are generally exotic or alien species having the ability to compete with and replace native species in natural habitats, thereby threatening native biological diversity. they have special characteristics that enable them to spread rapidly and aggressively and compete with native flora and fauna, to form a dense population that interferes with the natural development of biotic communities. meethirigala forest has cleared for several plantations is the main reason for spreading invasive species. figure 7. z. regia in the meethirigala forest reserve. 5. conclusion meethirigala forest reserve is rich and diverse in floristic composition and distribution (a total of 138 floristic species) and it is an isolated fragmented forest patch that should be protected as a biodiversity refugium in the wet zone which could enhance the floristic diversity and also the viability of plant species population. findings of the study could be useful in preparation of conservation plans for the meethirigala forest reserve. since this study has found endangered and threatened species in the forest. the finding from this study may help government and other stakeholders in providing baseline information, supported by scientific evidence, which can further contribute to more informed policy and decision-making processes. soil also can have considerable influence on tree species composition in different topographic levels in the forest. therefore, soil quality in each site can be used as an indicator of floristic composition. analysis of population structures for each individual tree species could provide more realistic and specific information for conservation measure. kalubowila et al/ journal of tropical forestry and environment vol. 10 no. 01 (2020) 63-74 71 references ariyarathne, w.a.m.p., yakandawala, d., samuel, m.r. and wijesundara, s., 2017. evaluating the occurrence and conservation status of sri lankan species of anacardiaceae. ceylon journal of science, 46:59-67. ashton, m., gunatilleke, c.v.s., gunatilleke, i.a.u.n., de zoysa, n. dassanayake, m.d. and wijesundara, s.a., 1997. a field guide to the common trees and shrubs of sri lanka. wildlife heritage trust publications (pvt.) ltd, sri lanka. bambaradeniya, c., 2008. western province biodiversity profile and conservation action plan. biodiversity secretariat, ministry of environmental and natural resources, sri lanka. carlos, i.e., omar, c. and arantzazu, l.l., 2010. what factors affect diversity and species composition of endangered tumbesian dry forests in southern ecuador. biotropica, 43:15-22. dassanayake, m.d. and fosberg, f.r., 1980-1991. revised handbook to the flora of ceylon, volumes i-vii. amarind publishing company, new delhi. dong, j.y. and ji, h.k., 2011. comparative evaluation of species diversity indices in the natural deciduous forest of mt. jeombong. forest science and technology, 7:68-74. fauna and flora protection (amendment) act, no. 22 of 2009. parliament of the democratic socialist republic of sri lanka. green, m.j., how, r., padmalal, u.k.g.k. and dissanayake, s.r.b., 2009. the importance of monitoring biological diversity and its application in sri lanka. tropical ecology, 50:41. gunatilleke, c.v.s. and gunatilleke, i.a.u.n., 1984. distribution of tree flora of a lowland hill forest in sri lanka. biological conservation. 28:275-285. hewage, s., 2011. studies on natural habitat and clonal propagation of zeuxine regia (iruraja) and zeuxine flava (sandaraja). m.phil. dissertation, university of sri jayewardenepura nugegoda, sri lanka. international union for nature conservation (iucn), 2001. iucn red list categories and criteria: version 3.1. iucn species survival commission. iucn, gland, switzerland and cambridge, uk. legg, c. and jewell, n., 1995. a 1:50,000-scale forest map of sri lanka: the basis for a national forest geographic information system. sri lanka forester (special issue): 3-24 mattsson, e., persson, u.m., ostwald, m. and nissanka, s.p., 2012. redd+ readiness implications for sri lanka in terms of reducing deforestation. journal of environmental management. 100:29-40. mittermeier, r.a., turner, w.r., larsen, f.w., brooks, t.m. and gascon, c., 2011. global biodiversity conservation: the critical role of hotspots. f.e. zachos, j.c. habel (eds.), biodiversity hotspots, springer publishers, london, pp. 3-22. perera, g.a.d., 2001. the secondary forest situation in sri lanka: a review. journal of tropical forest science, 13:768-785. perera, k. and tsuchiya, k., 2009. experiment for mapping land cover and its change in south eastern sri lanka utilizing 250 m resolution modis imageries. advances in space research. 43:13491355. singhakumara, b.m.p., 1995. floristic survey of adam’s peak wilderness, sri lanka, forest department, sri lanka. suraweera, a.v., balagalle, w.g. jayatilaka, k., lakdusinghe, s., and wijetunga, w.m.k., 1999. gampaha district socio-cultural studies, sri lanka. (publication in sinhala), department of cultural affairs. the national red list, 2012. conservation status of the flora and fauna. biodiversity secretariat of the ministry of environment and national herbarium, department of national botanic gardens of sri lanka. 72 williams, k.j., ford, a., rosauer, d.f., de silva, n., mittermeier, r., bruce, c., larsen, f. w., margules, c., 2011. forests of east australia: the 35th biodiversity hotspot, springer publishers, london. pp. 295-310. appendix 1 botanical name family life form taxonomic status conservation status strobilanthes adenophora acanthaceae shrub endemic vu trichadenia zeylanica achaceaeria tree endemic lc mangifera zeylanica anacardiaceae tree endemic lc semicarpus gardneri anacardiaceae tree endemic lc semicarpus acuminata anacardiaceae tree endemic vu semicarpus marginata anacardiaceae tree endemic en semicarpus sp anacardiaceae tree nothopegia beddomei anacardiaceae tree indegenous lc anacardium occidentale anacardiaceae tree indegenous lannea coremandelica anacardiaceae tree indegenous lc mangifera indica anacardiaceae tree exotic camponosperma zeylanica anacardiaceae tree endemic lc uvaria zeylanica annonaceae climber indegenous lc cyathocalyx zeylanica annonaceae tree indegenous lc polyalthia cerasoides annonaceae tree indegenous lc polyalthia korinti annonaceae tree indegenous lc xylopia paviflora annonaceae tree indegenous lc desmos elegans annonaceae tree endemic vu goniothalamus gardneri annonaceae shrub endemic vu miliusa indica annonaceae shrub indegenous lc alstonia macrophylla apocynaceae tree exotic alstonia scolaris apocynaceae tree indegenous lc ochrosia oppositifolia apocynaceae tree indegenous vu pagiantha dichotoma apocynaceae tree indegenous lc leptadenia reticulate apocynaceae climber indegenous lc caryota urens arecaceae tree indegenous lc areca sp arecaceae tree areca catechu arecaceae tree indegenous phoenix pusilla arecaceae tree indegenous lc calamus thwaitesii arecaceae climber indegenous vu canarium zeylanicum burseraceae tree endemic vu bhesa ceylanica celastraceae tree endemic lc calophyllum inophyllum clusiaceae tree indegenous lc calophyllum bracteatum clusiaceae tree endemic nt calophyllum walker clusiaceae tree endemic vu garcinia quaesita clusiaceae tree endemic lc garcinia echinocarpa clusiaceae tree indegenous vu combretum albidum combretaceae climber indegenous terminalia arjuna combretaceae tree indegenous lc connarus championii connaraceae climber endemic nt dillenia retusa dilleniaceae tree indegenous lc dillenia triquetra dilleniaceae tree indegenous lc schumacheria castaneifolia dilleniaceae tree endemic lc tetracera sarmentosa dilleniaceae climber indegenous lc dioscorea pentaphylla dioscoreaceae climber indegenous lc dipterocarpus zeylanicus dipterocarpaceae tree endemic nt shorea sp dipterocarpaceae tree shorea sp. dipterocarpaceae tree kalubowila et al/ journal of tropical forestry and environment vol. 10 no. 01 (2020) 63-74 73 diospyros insignis ebenaceae tree endemic nt diospyros walkerea ebenaceae tree indegenous vu diospyros hirusta ebenaceae tree endemic vu elaeocarpus serratus elaeocarpaceae tree indegenous lc botanical name family life form taxonomic status conservation status hevea brasiliensis euphorbiaceae tree indegenous bridelia mooni euphorbiaceae tree endemic lc bridelia retusa euphorbiaceae tree indegenous lc macaranga peltata euphorbiaceae tree indegenous lc aporusa lanceolata euphorbiaceae tree endemic lc chaetocarpus castanocarpus euphorbiaceae tree endemic lc mallotus rhamnifolius euphorbiaceae tree indegenous lc sauropus androgynous euphorbiaceae shrub indegenous lc aporusa lindleyana euphorbiaceae tree indegenous erythrozylum zeylanicum erythoroxylaceae tree endemic lc adenanthera pavonina fabaceae tree indegenous lc entada pusaetha fabaceae climber indegenous lc humboldtia laurifolia fabaceae shrub indegenous lc albizia lebbeck fabaceae tree indegenous nt acacia mangium fabaceae tree exotic archidendron bigeminum fabaceae tree indegenous lc hydnocarpus venenata flacourtiaceae tree endemic lc salacia oblonga hippocrateaceae tree indegenous en stemonurus apicalis icacinaceae tree endemic nt litsea longifolia lauraceae tree endemic lc cinnanmomum cassia lauraceae tree indegenous lc cryptocarya wightiana lauraceae tree indegenous nt pterospermum suberifolium malvaceae tree indegenous lc osbeckia aspera melastomataceae shrub indegenous nt osbeckia octandra melastomataceae shrub endemic lc aphanamixis polystacha meliaceae tree indegenous vu chukrasia tabularis meliaceae tree indegenous nt swieteniav mahogoni meliaceae tree exotic dysoxylum ficiforme meliaceae tree indegenous nt coscinium fenestratum menispermaceae climber indegenous lc artocarpus nobilis moraceae tree endemic lc ficus benghalensis moraceae tree indegenous lc artocarpus incises moraceae tree exotic artocarpus heterophyllus moraceae tree indegenous ficus exasperate moraceae tree indegenous lc horsfieldia iryaghedhi myristicaceae tree endemic vu myristica dactyloides myristicaceae tree indegenous lc horsfieldia irya myristicaceae tree indegenous lc syzygium amphoracecarpus myrtaceae tree endemic nt syzygium caryophyllatum myrtaceae tree indegenous lc syzygium rubicundum myrtaceae tree indegenous ne syzygium sp. myrtaceae tree cleistocalyx operculatus myrtaceae tree endemic lc syzygium gardneri myrtaceae tree indegenous lc syzygium cumini myrtaceae tree endemic lc gomphia serrate ochnaceae tree indegenous lc olax zeylanica oleaceae tree indegenous lc ochlandra stridula poaceae shrub endemic lc piper sylvestre piperaceae climber indegenous lc 74 ziziphus oenoplia rhamnaceae shrub indegenous lc anisophyllea cinnamomoides rhizophoraceae tree endemic nt carallia brachiate rhizophoraceae tree indegenous nt canthium rheedii rubiaceae tree indegenous nt botanical name family life form taxonomic status conservation status gaertnera vaginans rubiaceae shrub indegenous lc morinda citrifolia rubiaceae tree indegenous lc ixora coccinea rubiaceae tree indegenous lc psychotria sarmentosa rubiaceae climber indegenous nt wendlandia bicuspidate rubiaceae tree endemic lc acronychia pedunculata rutaceae tree indegenous lc melicope lunu-ankenda rutaceae tree indegenous lc zanthoxylum rhesta rutaceae tree indegenous en thoddalia asiatica rutaceae climber indegenous lc micromelum minutum rutaceae tree endemic lc flacourtia indica salicaceae tree indegenous lc filicium decipiens sapindaceae tree exotic lc dimocarpus longan sapindaceae tree indegenous lc nephelium lappaceum sapindaceae tree exotic sapindus trifoliata sapindaceae tree indegenous nt harpullia arborea sapindaceae tree indegenous vu pometia pinnata sapindaceae tree indegenous lc chrysophyllum roxburghii sapotaceae tree indegenous nt mimusops elengi sapotaceae tree indegenous nt madhuca longifolia sapotaceae tree indegenous nt smilax perfoliata smilacaceae climber indegenous lc symplocos cochinchinensis symplocapaceae tree indegenous lc gyrinops walla thymelaeaceae tree indegenous vu grewia carpinifolia tiliaceae tree indegenous lc grewia orientialis tiliaceae tree indegenous lc microcos paniculata tiliaceae tree indegenous lc clerodendrum infortunatum verbanaceae tree indegenous lc stachytarpheta urticaefolia verbanaceae shrub indegenous vitex altissima verbanaceae tree indegenous nt ampelocissus indica vitaceae climber indegenous nt unidentified 1 unidentified 2 unidentified 3 appendix 2 conservation status species name endangered semicarpus marginata, salacia oblonga, zanthoxylum rhesta vulnerable semicarpus acuminate, desmos elegans, goniothalamus gardneri, ochrosia oppositifolia, calamus thwaitesii, canarium zeylanicum, garcinia echinocarpa, diospyros walkerea, diospyros hirusta, strobilanthes adenophora marasinghe et al. /journal of tropical forestry and environment vol. 8, no. 02 (2018) 29-41 29 putrescible waste landfills as bird habitats in urban cities: a case from an urban landfill in the colombo district of sri lanka s.s. marasinghe1, p.k.p.perera1*, p.n. dayawansa2 1department of forestry and environmental science, university of sri jayewardenepura, nugegoda, sri lanka 2 department of zoology and environment sciences, university of colombo, sri lanka date received: 10-09-2018 date accepted: 05-12-2018 abstract as putrescible waste landfills are reliable and rich sources of food, these man-made habitats can support large populations of avifauna composed of different feeding guilds. unusually high population inflations of few opportunistic species of birds could impose a severe impact on the overall ecological balance. we studied the bird community in an open waste dump located in a highly urbanised area in the colombo district, sri lanka. bird census were performed using block counts in two contrasting sites of the landfill i.e., active dumping area and inactive dumping area between april 2015 and march 2016. abundance and density of birds were significantly higher in the active dumping area than in the inactive area. the inactive dumping area accounted for the highest avifaunal richness, diversity and evenness. bubulcus ibis and corvus splendens were the dominant species at the active dump, and their foraging and social behaviors probably discouraged other bird species from exploiting food resources in the dump despite belonging to different feeding guilds. the forging bird community at the landfill exhibit ed seasonal variations in abundance and other interspecific interactions. since the influx of large numbers of birds to landfills can potentially cause numerous environmental issues in urban areas, the current study highlights the importance of study of the seasonal patterns of bird communities in relation to location and management of landfills. keywords: urban landfills, feeding guilds, cattle egret, house crow, nuisance birds, waste management 1. introduction amidst the ever escalating human population and urbanization, effective management of municipal solid waste has become one of the major concerns in urban environs (hoornweg and bhadatata, 2012). in many developing countries, the issue of solid waste management in cities is rapidly becoming an environmental and economic catastrophe as cities are centers of garbage production (sharholy et al., 2008). tons of municipal solid waste, mainly comprising of nonhazardous garbage, rubbish and trash from homes, institutions, and industrial facilities often end-up in urban landfills. landfill construction for solid waste disposal not only removes suitable habitats for certain wildlife species but also enhances certain other human-wildlife interactions. such interactions may have both positive as well as negative impacts on wildlife populations. some common ecological repercussions of landfills include alteration/loss of wildlife habitats, increased behavioral disturbances including habituation and functioning as food subsidies for certain species, thus the abnormal increase in a few species causing ecological imbalance (patton, 1988; blanco, 1996; elliott et al., 2006). *correspondence: priyan@sjp.ac.lk tel: +94 112758411, fax: +94 112803470 issn 2235-9370 print/issn 2235-9362 online ©2017 university of sri jayewardenepura 30 among different faunal species, avifauna has been specifically used as a biological indicator in studying anthropogenic influences on animals because of their well-known taxonomy (o’connell et al., 2000; gregory and strien, 2010; perera et al., 2017), ecology (padoa-schioppa et al., 2005), links among bird communities, vegetal associations and territories (keast, 1990; petty and avery, 1990), coverage of different levels of ecological pyramids in most environments (bunce et al., 1981; burrough, 1986) and ease of detection that allows rapid data collection on presence/ absence or abundance (haila, 1985; wiens, 1989; perera et al., 2017). putrescible waste landfills in urban settings are known to support high abundance of birds. putrescible waste is “solid waste that contains organic matter capable of being decomposed by microorganisms and of such a character and proportion as to cause obnoxious odors and to be capable of attracting or providing food for birds or animals’’ (argonne national laboratory). such landfills provide reliable and rich sources of food as well as potential to support large communities of avifauna representing different feeding guilds (belant et al., 1995; jackson et al., 1999; restaniet al., 2001; turrin et al., 2015). previous studies have identified putrescible waste landfills as the primary cause for increased abundance of certain bird species on a local and regional scale, as the carrying capacity reached new levels due to ample availability of food within landfills. on the other hand, with the concomitant decline in many natural habitats, human modified habitats such as landfills are increasingly becoming important habitats for numerous avian species. as birds adapt to an environment increasingly dominated by humans, their social behavior and demography is likely to change, and species that rely on anthropogenic foods may form stable social organisations with consistent dominance hierarchies in places such as putrescible waste landfills (saalfeld et al., 2013). furthermore, less-stable assemblies of vagrant bird species may also form periodically. although birds on landfills perform valuable ecological functions (whelan et al., 2008), unusually high populations of a few bird species with low species richness can have negative impacts on the overall proportions of certain species (mills et al. 1989; cam et al., 2000). conditions in landfills may favor aerial insectivores, granivores and ground foraging insectivores (allen and o’conner, 2000; ciach and kruszyk, 2010). on the other hand, birds may cause conflicts with human interest with respect to noise, birds carrying litter off site, possible transmission of pathogens in bird droppings, pollution of water near roosting sites due to droppings, increased risks of bird-strikes/collisions and affecting the day to day site operations at landfills (jackson et al., 1999; burger, 2001; dolbeer, 2006; cook et al., 2008; martin, 2012). as such, control and management of landfill birds has been recognized as an important aspect in urban landfill management (cook et al., 2008; martin, 2012). in the sri lankan context, the severity of the solid waste management issue is rising with the rapid economic development and urban expansion. open dumping or landfilling are the most common ways of disposing solid waste in sri lanka, mainly due to the high cost involved with advanced technologies of landfilling, lack of technical capacity, and lack of knowhow (bandara and hettiaratchi, 2010). several large-scale landfills/open dumps are currently in operation in major cities and suburbs where the majority of them are in association with wetlands, thus replacing the urban wetland ecosystems. open dumps function as important foraging grounds for numerous urban wildlife species. large populations of crows and cattle egrets commonly occupy these landfills along with other species which are less abundant. as any major changes in waste management and disposal practices such as changing from landfilling to incineration can potentially have sizeable impacts on bird populations depending on landfills, better understanding of the extent and patterns of daily use of landfills by birds and their seasonal dynamics in abundance is highly important. such ecological information would be useful for regulatory agencies and local governments in decision making pertaining to the management of landfills. however, limited or no studies in literature have investigated the effects of landfills on the spatial and temporal distribution of birds and other wildlife species foraging at landfills in sri lanka. hence there is a dearth of knowledge about landfills and their interaction with wildlife thus, this study was designed to bridge this existing literature gap. the study assessed the diversity and abundance of birds at the marasinghe et al. /journal of tropical forestry and environment vol. 8, no. 02 (2018) 29-41 31 karadiyana landfill in the colombo district; the largest operating landfill in sri lanka. it further examined the temporal changes and functional diversity of the bird community via analysing feeding guild structures to assess the importance of putrescible waste landfills as a source of food for different avian feeding guilds. 2. materials and methods 2.1 study site this study was conducted at the karadiyana landfill site (6°48'44.97"-6°49'0.76"n, 79°54'4.60"79°54'20.78"e) located in the colombo district, sri lanka (figure 1). the entire landfill is approximately 10.12ha in extent, which over the years, has replaced a natural marshland ecosystem. figure 1: map of the location of karadiyana landfill site. 32 the average annual rainfall in the study area is over 2000 mm, while the temperature ranges from 27 to 31o c (punyawardena 2008). municipal waste, domestic waste and industrial waste from seven local authorities are dumped into this landfill. daily waste dumping activities are generally carried out from 6.30 am to 6.30 pm in a 12-hour shift. the landfill comprises of two major management zones: zone a which is the active dumping/operating site and zone b which is an inactive area (figure 1). the active dumping site is approximately 4.85 ha in extent, which consists of administrative office buildings, vehicle yards, composting yard with shelter, and the active dumping area. for this study, the active dumping area was defined as the area where daily dumping activities are carried out by workers and machinery. the extent of this active dumping area is estimated to be approximately 2.27 ha. inactive site (zone b) is approximately 5.27 ha in extent, where operations have not been carried out for the past five years. as no fresh garbage is dumped over this area, the surface is comparatively dry. the area also encompasses marshland, with some parts of the old dumping area being colonized by a mixed vegetation of annonaglabra, cerberamanghas, and melastoma sp. 2.2 bird census during the preliminary field survey, it was found that the avian community foraging in active and inactive dumping areas is different in terms of species composition and abundance of assemblages. this is owing to the heterogeneity in resource availability (food and cover) at the two sites. to capture the diversity of birds occupying the entire landfill, both active and inactive dumping sites were sampled. block count method (norton-griffiths, 1978) was used to conduct the census of birds. blocks were demarcated by locating random points in space with reference to the physical features present on the ground of the landfill. only birds those were directly foraging on active or inactive dumping surfaces and the birds restricted to the fringes of the dump i.e. the dumpsite-wetland interface and dumpsite-built-up area interface were counted. data collection lasted for a period of 12 months from april 2015 to march 2016. bird counts were conducted in each zone in 6 different time slots of the day from 0600h (dawn) to 1800h (dusk), i.e., 0600h-0800h, 0800h-1000h, 1000h-1200h, 1200h-1400 h, 1400h-1600h and 1600h-1800h, each month. about 15 minutes were spent in each study site and block count session/bird census was conducted. different bird species inhabiting each site were identified and the number of individuals representing each bird species was recorded. a nikon©aculon 10x50 binocular was used to facilitate bird identification and counting as necessary. the species those were difficult to identify at the location, were photographed and identified by using published descriptions/ field guides. the counting was conducted as quickly as possible to avoid any bias associated with multiple counting that may occur due to the movement of individuals from one area to another. birds that move from a counted block to uncounted one (or vise-versa) were noted and the final block counts were adjusted accordingly. two consecutive counts of birds on each block were made to improve accuracy and the average was calculated. a total of 144 counts were completed during the study period, i.e. 72 counts at both the active and inactive dumping site respectively. observer bias was minimised as block counts of birds was conducted by the same field observer throughout the study period. while conducting the census, vehicles used for daily waste dumping operations were used for transportation inside the landfill site to minimise additional disturbances to birds as these species were found to be habituated to the vehicles. marasinghe et al. /journal of tropical forestry and environment vol. 8, no. 02 (2018) 29-41 33 2.3. data analysis relative abundance of each species and each feeding guild (carnivore, omnivore, granivore and insectivore) in the two main habitat types, species richness, species diversity and evenness indices were used to explore the complexity of avifaunal community inhabiting different habitats of the dumping site. accordingly, shannon-weiner diversity index (h´) (tramer, 1969), margalef’s index of species richness (margalef, 1958) and pielou’s evenness index (e) (pielou, 1966) were used to describe the ecology of avifauna. jaccard coefficient of community similarity was used to contrast the community distinctiveness between the active dumping site and inactive dumping site (whittaker, 1960). for all the recorded bird species, data at individual species level were insufficient to proceed with subsequent statistical analysis to explore temporal patterns of variation in their occurrence. hence, the detection probability of greater than 25% for a species (calculated by dividing the counts where the species was present by total number of counts) was used as the screening criterion to investigate specieslevel dynamics (alwiset al., 2016). all collected data were pooled together as there was no considerable difference in bird abundance between different time slots of the day. hypothesis testing was performed using non-parametric statistical techniques in pasw© v.18. mann-whitney u test (at α=0.05 level) was used to examine whether individual species abundance differ significantly between active and inactive dumping surfaces. 3. results 3.1. diversity of birds at the landfill during 144 counting sessions conducted over the period of 12-months, a total of 61,293 individual birds belong to 24 species and 15 families were recorded foraging in the landfill (appendix 1). avian community at the karadiyana landfill site were dominated by cattle egret (bubulcus ibis), house crow (corvus splendens), feral pigeon (columba livia) and common myna (acridotheres tristis). cattle egret, house crow, common myna, feral pigeon, red-rumped swallow (cecropis hyperythra), indian pond heron (ardeola grayii), black-headed ibis (thresironis melanocephalus), brahminy kite (haliastur indus), and black-crowned night heron (nycticorax nyticorax) used both active and inactive dumping surfaces for foraging. house sparrow (passer domesticusindicus), yellow wagtail (motacilla thumbeigi), red-wattled lapwing (vanellus indicus) and paddy field pipit (anthus rufulus) were recorded foraging in the inactive dumping site while little egret (egretta garzetta) and great egret (casmerodius albus) predominantly used the active dumping site as a foraging site. the highest species richness was recorded from the inactive dumping site (table 1). table 1: species richness in the two habitat types. habitat type no. of species margalef’s species richness active dumping site 11 0.674 inactive site 14 1.430 entire site 16 1.412 highest shannonweiner diversity index was recorded from the inactive dumping site (table 2). although the abundance of bird species was comparatively low in the active dumping site, this habitat accommodates a greater diversity of species. in contrast, the active dumping site was less diverse; however the density of birds was much higher. pielou’s evenness was highest in the inactive dumping site (table 2). the active dumping area was dominated by the cattle egret and house crow, while other species were recorded in low numbers. this resulted in low evenness at the active dumping area. 34 table 2: species diversity and evenness of two habitats. habitat species diversity (h') species evenness (e) active dumping site 1.0423 0.4291 inactive site 1.9068 0.7225 entire site 1.3952 0.5032 active and inactive dumping areas represent two different resource patches for birds. thus, the species composition and abundance are likely to differ between the two sites. mannwhitney u test on abundance of bird species with a detection probability of 0.25 found that, the abundance of cattle egret, house crow, feral pigeon, indian pond heron, black-headed ibis and brahminy kite varied significantly (p<0.05) between the active and inactive dumping surfaces (table 3). table 3: comparison of the abundance of birds between active and inactive dump surfaces. no common name scientific name mean rank z p value active site inactive site 1 cattle egret bubulcus ibis 89.88 42.24 -7.157 0.000 2 house crow corvussplendens 99.40 36.54 -9.371 0.000 3 feral pigeon columba livia 71.52 45.66 -4.066 0.000 4 common myna acridotherestristis 64.24 59.08 -1.258 0.208 5 red-rumped swallow cecropishyperythra 44.10 36.40 -1.430 0.153 6 indian pond heron ardeolagrayii 68.19 50.57 -2.823 0.005 7 black headed ibis thresironismelanocephalus 17.89 25.87 -2.134 0.033 8 brahminy kite haliasturindus 61.93 25.13 -5.818 0.000 statistical significance at α=0.05 level. 3.2. temporal changes in the abundance of dominant landfill birds cattle egrets were the dominant species at the active dumping site. they tend to dominate the active dumping area from november to april. however, their numbers substantially declined during the period of may to october, possibly due to migratory behaviour (figure 2a). their numbers in the inactive dumping area also showed a similar trend in abundance with time. in contrast, the house crow population at the active dumping area was low during the period of november to april. in the absence of cattle egrets, the house crow population showed a substantial increase during the period of may to october (figure 2b). abundance of feral pigeon and common myna also increased in the active dumping site in the absence of cattle egrets (figure 2c and 2d). the abundance of black-headed ibis markedly increased in june and july, though their actual numbers were comparatively low (figure 2g). red-rumped swallow, indian pond heron and brahminy kite populations at the landfill did not show marked fluctuations throughout the study period. (figure 2e, 2f, and 2h). marasinghe et al. /journal of tropical forestry and environment vol. 8, no. 02 (2018) 29-41 35 figure 2: monthly relative abundance of (a) cattle egret, (b) house crow, (c) feral pigeon, (d) common myna, (e) redrumped swallow, (f) indian pond heron, (g) blackheaded ibis and (h) brahminy kite. 36 3.3. feeding guild structure and composition bird census identified four feeding guilds at the landfill site; carnivore, omnivore, granivore and insectivore (figure 3). the most abundant feeding guild at the active dumping site was carnivores followed by omnivores, granivores and insectivores. the most abundant guild at the inactive site was omnivores. carnivore feeding guild in the active dumping site was mainly represented by cattle egret, indian pond heron, black-headed ibis, and brahminy kite while the house crow and common myna represented the omnivore feeding guild. omnivore feeding guild at the inactive dumping site was mainly represented by the house crow and common myna, while the red-rumped swallow, barn swallow and feral pigeon comprised the insectivore feeding guild. when considered the feeding guild assemblage at the karadiyana landfill site, carnivore was the dominant feeding guild. this was followed by feeding omnivore and insectivore feeding guilds. figure 3: relative abundance of feeding guilds in active dumping site, inactive dumping site and entire landfill. the null hypothesis of “abundance of birds belonging to each feeding guild does not differ between the active and inactive dumping surfaces” was statistically tested. results revealed that the abundance of carnivore, omnivore and granivores varied significantly between the two sites. abundance of carnivores and omnivores were significantly high at the active dumping surface. table 4: mann-whitney u test analysis results of the feeding guilds no feeding guild mean t p value active inactive 1 carnivore 211.36 173.62 -3.317 0.001 2 omnivore 159.95 101.62 -6.264 0.000 3 granivore 71.52 45.66 -4.066 0.000 4 insectivore 44.10 36.40 -1.430 0.153 statistical significance at α=0.05 level 4. discussion karadiyana landfill is located in a marshy land and is of close proximity to the bolgoda lake. hence the surrounding area naturally supports considerable bird diversity. however, the human-modified urban landfill site harbors a high abundance and low diversity of birds. during block counts, 24 bird species were recorded inside the landfill. those species directly depended on various food resources available at the landfill. among those, 11 species were observed at the active dumping site where the daily dumping activities were carried out, and 14 species were observed at the inactive site. by far, the three most abundant species foraging on the landfill included cattle egret, house crow and common myna, suggesting that these species are the major exploiters of food resources at the landfill. 0 20 40 60 80 100 active dumping site inactive site entire site r e la ti v e a b u n d a n c e insectivore grainivore omnivore carnivore marasinghe et al. /journal of tropical forestry and environment vol. 8, no. 02 (2018) 29-41 37 4.1 landfill resource utilization patterns by birds composition, quality and quantity of the garbage, level of human interferences and waste management/site operation activities were substantially different at the two habitats, thus providing unique environmental conditions and foraging opportunities to birds. the highest species richness and diversity were recorded at the inactive dumping site. the area was predominantly comprised of plastics, polythene, non-biodegradable materials and other biodegradable materials that decompose at a slower rate. organic food items in the form of garbage were less abundant at the inactive dumping site. however, the inactive dumping surface provides ideal breeding grounds for a variety of insects, and as a result, numerous other species such as lizards, small snakes etc. could be found here. as such, the inactive dumping area allows variety of foraging opportunities for birds. this is evident from the feeding guild analysis which revealed omnivores and insectivores dominating the inactive dump site. common myna and house crow were the dominant omnivores occupying the inactive landfill site. apart from directly consuming food items available at the site, these omnivores also use the inactive dump site as a place with less interference to consume food items picked up from the active dump site where the disturbances from other birds and humans were more persistent. insectivores such as the red-rumped swallow, paddy field pipit, and yellow wagtail were predominantly dependent on insects available at the inactive site. large flocks of migrant barn swallow were also recorded foraging at the inactive dump site. members of the carnivore feeding guild i.e. cattle egret and brahminy kite mainly utilised the inactive dump site for resting, although opportunistic foraging was evident. in contrast, other members of the carnivore feeding guild such as little egret, indian pond heron, black-crowned night heron, great egret, gray heron and purple heron seemed to be actively exploiting food resources available at the inactive dump, in the form of small vertebrates, insects and snails. species richness and species diversity were comparatively lower at the active dumping surface than at the inactive site. few dominant species displaced the others from foraging on the active dumping surface. the most abundant species in the active dumping site as well as in the entire landfill, the cattle egrets are known as cosmopolitan due to their ability to adapt to different habitats and spread over anthropogenic habitats such as lawns and landfill sites (seedikkoya et al., 2007; abigail et al., 2013). reliable and abundant food availability may be the primary reason for birds such as cattle egrets to become attracted to landfills. for instance, a recent study investigated the foraging success and efficiency of cattle egrets in three habitat types (grassy areas, silted drain, and landfill sites) and found that the foraging efficiency is highest at the landfill sites (abigail et al., 2013). as pray species are readily available, the birds can substantially cut-down the energy budget on foraging activities. as a consequence, the population levels can surge as more energy could be reserved for breeding (siegfried, 1971). in sri lanka, there are migrating and resident breeding populations of cattle egrets (henry, 1998). according to field observations, cattle egrets were absent from june to september, which may resemble their movement pattern. interestingly, the abundance of house crow at the active dumping site was drastically increased with the absence of cattle egrets in the landfill. this increased abundance could be due to reduced competition. the realised niche of house crows will extend to the larger fundamental niche of open dumping site in the absence of the competitor. this change further indicates a shift in dominant feeding guild from carnivore to omnivore. house crow of omnivore feeding guild was the second most abundant in both active and inactive dumping zones that forage on fresh garbage. house crows are opportunistic and inventive breeders (ryall, 2003). according to soh et al. (2002), reproductive success of corvids can be higher in the urban areas than in local wild lands because of their positive association with urban environments. 4.2 landfill site operations and foraging behaviours of birds site vehicles working in the dump affected the foraging behavior of birds to avariable extent, and the proximity to disturbance can affect the foraging behaviour of birds (burger and gochfeld, 1983; 38 bellebaum, 2005). however, burger and gochfeld (1983) observed no such correlation with regard to cattle egrets foraging in landfills. field observations made in this study contradict burger and gochfeld (1983)’s observations as unusually high densities of cattle egrets were observed near operating vehicles. ground disturbances that occur during the operation of site vehicles expose maggots and worms just underneath the surface, and cattle egrets were taking a greater risk by feeding earlier and closer to site vehicles mainly to avoid intra-specific competition. this is comparable to commensalism that cattle egrets exhibit in other environments where they tend to forage in close association with cattle, and feed on insects disturbed from the grazing and movement of cattle. the house crow and common myna also exhibited similar foraging behaviour to a certain extent where they took advantage of newly exposed edible items from daily site operations. feeding guild analysis revealed feeding overlaps among bird species, creating interspecific competition (pohajdak, 1998). larger numbers of house crows and brahminy kites tend to concentrate at the usual time of the day where slaughter house waste is brought-in and dumped at the site. intense competition for the same food source takes place during this time. species relationships such as kleptoparasitism (bolen and robinson, 2002) were also evident in this man-made ecosystem where brahminy kites were observed stealing food items picked up by house crows from the dump. vise-versa of the same scenario was also observed occasionally where two or more house crows teamed-up to snatch food from brahminy kites. furthermore, the physical interferences due to the presence and foraging behaviors of large number of cattle egrets probably discourage other species to exploit food on the active dumping zone even in the absence overlapping of diet with cattle egrets. this is supported by the observation of the house crow, common myna, and feral pigeon (omnivore and insectivore feeding guilds) dominating the active dumping surface during the period of june to september, in the absence of cattle egrets. among the 8 species which have sufficient data, the abundance of 6 species; cattle egret, house crow, feral pigeon, red-rumped swallow, indian pond heron and brahminy kite were significantly different between the active and inactive dumping areas. this difference is mainly due to the availability and abundance of food types as well as the degree of human induced disturbances in the two habitats. in this study, it was observed that all landfill birds occupying the active dumping zone seem to be habituated to moving vehicles and human presence. cattle egrets and house crows seem to tolerate greater disturbances. in contrast, members in the insectivore feeding guild showed less tolerance to human disturbances, hence confined to the inactive dumping zone where no major human disturbances are present. cattle egrets perform an important ecological role in the environment as a scavenger and a natural pest/insect controller (blaker, 1969; abigail et al., 2013). they are reported to exploit housefly (musca domestica) and blue bottle fly (calliphora spp.) maggots in landfills which are vectors of the pathogens that cause diseases such as typhoid, dysentery, cholera and poliomyelitis (seedikkoya et al., 2007; jayaratne et al., 2015). although cattle egrets are considered carnivores, it predominantly depends on an insectivorous diet with occasional scavenging for edible refuse at the dump. according to seedikkoya et al. (2007), a cattle egret can consume up to 100-150 g maggots per day. despite their ecological role, breeding colonies of cattle egrets may serve as vectors of zoonotic diseases and contribute to sanitation and aviation hazards in urban areas (baxter, 2005; pitt and witmer, 2007; abigail et al., 2013). similarly, house crow is also an important scavenger in urban landscapes, but a vector of human pathogens such as cholera, salmonella, giardia, shigella and escherichia. with their loud calls, social behaviour and aggressiveness towards other birds, house crows are further capable of displacing other birds from urban habitats, thus reducing the avian diversity (suliman et al., 2011; jayathilake and chandrasekara, 2015). hence, there is a need to manage landfill sites to control the populations of nuisance birds attracted to landfills. a common management practice in landfills/controlled dumps is the application of daily cover, which is necessary to abate odor and prevent the attraction of rodents and birds (talyan et al., 2008). water fog for repelling birds is also practiced in some countries (nachtman et al., 2000). marasinghe et al. /journal of tropical forestry and environment vol. 8, no. 02 (2018) 29-41 39 owing to the inherent nature of the study design, the findings of this study may have local applicability. past studies suggest that species composition and seasonal abundance of birds can vary considerably even among similarly operated landfills in close proximity (belant et al., 1995), and thebird use of landfill facilities is likely to be influenced by surrounding habitats or land-use (e.g. wetland, urban cities) than by the waste itself or onsite waste management activities (gabrey, 1997). therefore, sitespecific studies may be necessary to assess the use of landfills by birds and align on-site waste management practices to control bird populations in landfills. 5. conclusion the constant and abundant availability of food at landfills can attract large number of birds. the foraging bird community at karadiyana landfill site is characterised by low species diversity and richness, but high abundance and dominance of few species, especially cattle egret and house crow. presence of cattle egrets and house crows in large numbers, their foraging and social behaviours probably discourage other bird species from exploiting food resources on the working area of the landfill, even when there are no overlaps in diet among them. despite being a man-made urban ecosystem in a highly urbanised area, the forging bird community at the landfill exhibit complex ecological relationships among its members. favorable welfare factors at the landfill can potentially cause ecologically unstable increases in populations of few species, while posing health and safety concerns to humans. hence findings of this study stress the importance of considering the seasonal patterns of local and regional bird populations in relation to location and management practices of landfills. references abigail, k., rosina,k., daniel, a.k., holbech, l.h. 2013. foraging activities, success and efficiency of cattle egrets (bubulcus ibis) in three habitat types in the greater accra region of ghana. journal of biological and food science research, 2(4):45-50. allen, a.p., o’conner, r.j. 2000. hierarchical correlates of bird assemblage structure on northeastern usa lakes. environmental monitoring and assessment, 62:15–35. alwis, n.s., perera, p., dayawansa, n.p. 2016. response of tropical avifauna to visitor recreational disturbances: a case study from the sinharaja world heritage forest, sri lanka. avian research, 7: 15 doi: 10.1186/s40657-0160050-5. argonne national laboratory. http://tapseis.anl.gov/glossacro/dsp_wordpopup.cfm?word_id=873. accessed 01november 2018. bandara n.j., hettiaratchi, j.p.a. 2010. environmental impacts with waste disposal practices in a suburban municipality in sri lanka. international journal of environment and waste management, 6(1-2):107-116. baxter, t.a. 2005. effectiveness of best practice bird control on landfill sites in relation to gull feeding behaviour. international bird strike committee, athens . belant, j.l., seamans, t.w., gabrey, s.w., dolbeer, r.a. 1995. abundance of gulls and other birds at landfills in northern ohio. american midland naturalist, 134:30–40. bellebaum, j. 2005. brief report between the herring gull larusargentatus and the bulldozer: blackheaded gull larusridibundus feeding sites on a refuse dump. ornisfennica, 82:166-171. blaker, b.r. 1969. behaviour of the cattle egret (ardeola ibis). ostrich, 40(3):75-129. blanco, g. 1996. population dynamics and communal roosting of white storks foraging at a spanish refuse dump. colonial waterbirds, 273-276. bolen, c., a. robinson. 2002. wildlife ecology and management. 5th edition, prentice hall, nj. bunce, r.g., c.j. barr and h.a. whittaker. 1981. an integrated system of land classification. annual report institute of terrestrial ecology, pp 28–33. burger, j. 2001. landfills, nocturnal foraging, and risk to aircraft. j toxicol environ healthpart a, 64(3):273-290. http://tapseis.anl.gov/glossacro/dsp_wordpopup.cfm?word_id=873 40 burger, j., gochfeld, m. 1983. behavior of nine avian species at a florida garbage dump. colonial waterbirds, 6:54-63. burrough, p.a. 1986. principles of geographical information system for land resources assessment. monographs on soil and resources survey no. 12 oxford university press, oxford. cam, e., nichols, j.d., sauer, j.r., hines, j.e., flather, c.h. 2000. relative species richness and community completeness: birds and urbanization in the mid-atlantic states. ecological applications, 10:1196–1210. ciach, m., kruszyk, r. 2010. foraging of white storks ciconiaciconia on rubbish dumps on non-breeding grounds. waterbirds, 33(1):101-104. cook, a., rushton, s., allan, j., baxter, a. 2008. an evaluation of techniques to control problem bird species on landfill sites. environmental management, 41:834–843. dolbeer, r.a. 2006. height distribution of birds recorded by collisions with civil aircraft. journal of wildlife management, 70(5):1345-1350. elliott, k.h., duffe, j., lee, s.l., mineau, p., elliott, j.e. 2006. foraging ecology of bald eagles at an urban landfill. the wilson journal of ornithology, 118(3):380-390. gabrey, s.w. 1997. bird and small mammal abundance at four types of waste-management facilities in northeast ohio. landscape and urban planning, 37:223-233. gregory, r.d., strien, a.2010. wild bird indicators: using composite population trends of birds as measures of environmental health. ornithological science, 9:3–22. haila, y. 1985. birds as a tool in reserve planning. ornisfennica, 62:96–100. henry, g.m. 1998. a guide to the birds of sri lanka. oxford university press, usa. hoornweg, d., bhada-tata, p. 2012. what a waste: a global review of solid waste management. jackson, v.s., brown, j., allan, j.r. 1999. "a fixed netting system as a means of excluding birds from a domestic waste landfill" 1999 bird strike committee usa/canada, first joint annual meeting, vancouver, bc. jayaratne, r.l., perera, i.c., weerakoon, d.w., kotagama, sw. 2015. cattle egrets (bubulcus ibis) control the population of house flies (musca domestica) in garbage dumping sites: a comparison between two garbage dumping sites, kandy, sri lanka. in proceedings of international forestry and environment symposium (vol. 20). jayathilake, m.b., chandrasekara, w.u.2015. variation of avifaunal diversity in relation to land-use modifications around a tropical estuary, the negombo estuary in sri lanka. journal of asiapacific biodiversity, 8(1):72-82. keast, a. 1990.biogeography and ecology of forest bird communities. spb academic. margalef, r. 1958. information theory in ecology. international journal of general systems, 3:36-71. martin, j. 2012. investigations in to the ecology and management of a nuisance native bird in urban environments: the australian white ibis. doctor of philosophy thesis, school of biological sciences, university of wollongong. mills, g.s., dunning jr., j.b., bates, j.m. 1989. effects of urbanization on breeding bird community structure in southwestern desert habitats. condor, 91:416–428. nachtman, t.j., hull, j.h., clark, l. 2000. water fog for repelling birds. u.s. patent 6:24-971. norton-griffiths, m. 1978. counting animals (no. 1). serengeti ecological monitoring programme, african wildlife leadership foundation. o’connell, t.j., jackson, l.e,. brooks, r.p. 2000. bird guilds as indicators of ecological condition in the central appalachians. ecological applications, 10:1706–1721. padoa-schioppa, e., baietto, m., massa, r., bottoni, l.2005. bird communities as bio indicators: the focal species concept in agricultural landscapes. ecological indicators, 6:83-93. patton, s.r. 1988. abundance of gulls at tampa bay landfills. wilson bulletin, 100:431-442. perera, p., wijesinghe, s., dayawansa, n., marasinghe, s., wickramarachchi, c. 2017. response of tropical birds to habitat modifications in fragmented forest patches: a case from a tropical lowland rainforest in south-west sri lanka. community ecology, 18(2), 175-183. marasinghe et al. /journal of tropical forestry and environment vol. 8, no. 02 (2018) 29-41 41 petty, s.j., avery, m.i. 1990. forest bird communities. occasional papers 26. forestry commission, edinburgh. pielou, e.c. 1966. the measurement of diversity in different types of biological collections journal of theoretical biology 13:131-144. pitt, w.c., witmer, g.w. 2007. invasive predators: a synthesis of the past, present, and future. in predation in organisms (pp. 265-293) springer berlin heidelberg. pohajdak, g.c. 1998. feeding guilds, diets and foraging behavior of insectivorous passerines in a riparian habitat in manitoba. electronic thesis and dissertations. faculty of graduate studies, university of manitoba. punyawardena, b. v. r. 2008. rainfall and agro-ecological regions of sri lanka. natural resource management centre, department of agriculture, peradeniya, sri lanka, 13-17. restani, m., marzluff, j.m., yates, r.e. 2001. effects of anthropogenic food sources on movements, survivorship, and sociality of common ravens in the arctic. condor, 103:399–404. ryall, c. 2003. notes on ecology and behaviour of house crows at hoek van holland. dutch bird, 25:167-72. saalfeld, s.t., hill, b.l., lanctot, r.b.2013. shorebird responses to construction and operation of a landfill on the arctic coastal plain. condor, 115(4):816-829. seedikkoya k, azeez, p.a., shukkur, e.a.2007. cattle egret as a bio control agent. zoos’ print journal, 22(10):2864-2866. sharholy, m., ahmad, k., mahmood, g., trivedi, r. c. 2008. municipal solid waste management in indian cities–a review. waste management, 28(2), 459-467. siegfried, w.r. 1971. population dynamics of the cattle egret. african zoology, 6(2):289-292. soh, m.c.k., sodhi, n.s., seoh, r.k.h., brook, b.w. 2002. nest site selection of the house crow (corvussplendens) an urban invasive bird species in singapore and implications for its management. landscape and urban planning, 59:217-226. suliman, a.s., meier, g.g., haverson, p.j. 2011. eradication of the house crow from socotra island, yemen. island invasives: eradication and management. iucn, gland, switzerland, pp.361-363. talyan, v., dahiya, r.p., sreekrishnan, t.r. 2008. state of municipal solid waste management in delhi, the capital of india. waste management, 28(7):1276-1287. tramer, e.j. 1969. bird species diversity: components of shannon’s formula. ecology, 50:927-929. turrin, c., watts, b.d., mojica, e.k. 2015. landfill use by bald eagles in the chesapeake bay region. journal of raptor research,49(3):239-249. whelan, c.j., wenny, d.g., marquis, r.j. 2008. ecosystem services provided by birds. annals of the new york academy of sciences, 1134(1):25-60. whittaker, r.h. 1960. vegetation of the siskiyou mountains, oregon and california. ecological monographs, 30(3):279–338. wiens, j.a. 1989. landscape interactions, scaling and ecosystem dynamics. in: proceedings of the fourth annual landscape symposium, colorado state university. microsoft word 2 liyanage liyanage et al., /journal of tropical forestry and environment vol. 3, no. 01 (2013) 9-16 9 an assessment of the contribution of an analog forest as a sustainable land-use ecosystem for the development of rural green economy in sri lanka w.k.d.d. liyanage 1,2,3,* , s.n. gamage 3 , g.d.c. pushpa kumara 3 and l. xulong 2 1 forest department of sri lanka, divisional forest office, nuwara eliya, sri lanka 2 china university of geosciences, no. 388, lumo road, wuhan, hubei, 430074, p.r. china 3 land owners restore rainforests in sri lanka (lorris), bangamukande estate, pitigala, sri lanka date received: 20-11-2012 date accepted: 12-03-2013 abstract large scale clearing of natural forests for human settlements as well as in the form of tea, rubber and cinnamon plantations resulted forest fragmentation in most natural ecosystems in the wet zone of sri lanka which posed massive threats to both nature and the humans including the loss of biodiversity, environmental hazards and increasing poverty. this paper discusses about the potential to develop rural green economy as a result of consolidating these agricultural lands into analog forests as a sustainable land use practice. bangamukande estate, a man-made analog forest in galle district was selected for this assessment. participatory rural appraisal methods were used to obtain information on resource utilization by the local community in nearby villages. secondary data of the long term analog forestry establishment programme were also used for analysis the livelihood changes of the people due to the impacts this system. various interventions had been made to address the issues such as encouraging local farmers to cultivate timber, fruits, spices and medicinal plants, paying them for the environmental services they render and enhancing their income through green employment. the introduction of new sustainable agricultural activities such as bee keeping and planting fruits resulted in the production of value added farm products and organic fruits to be sold in the market. through environmental based tourism activities such as providing food and accommodation, eco-guidance, and assisting environmental research, the stakeholders are earning a better income supporting the development of a green economy in the country. key words: analog forest, sustainable land-use, green economy, green employment 1. introduction in recent decades, many researchers and sustainable farmers around the world have turned their practices from the extractive industrial model to ecology-based approaches, referred to as eco-agriculture, agro-forestry or analog forest after the value of biodiversity has been taken to consideration (earles, 2005; scherr and shames, 2006). thousands of farms have contributed to sustainable systems of agro-ecology that promotes biodiversity, recycling of plant nutrients, preventing soil erosion, conserving and protecting water. also uncultivated portions of agricultural landscapes can provide habitat patches for wildlife, and form corridors that bridging protected areas and allow species to continue their genetic contact with populations that would if not be isolated (scherr and shames, 2006). the number of wild plant and animal species in these agro-forests is often as high as in natural forests (scherr and shames, 2006; gamage et al., 2006; gamage et al., 2007 a ; gamage et al., 2007 b ; liyanage et al., 2009 a ; liyanage, 2009). *correspondence: wasantha_cug@yahoo.com tel: +94 71 4564411 issn 2235-9370 print / issn 2235-9362 online ©2013 university of sri jayewardenepura liyanage et al., /journal of tropical forestry and environment vol. 3, no. 01 (2013) 12-19 10 sri lanka shows the second highest density of the human populations in asia especially in the wet zone. a growing population, demand for subsistence land and a high proportion of endangered and endemic species within the wet zone of sri lanka have resulted in its being declared a critically endangered eco-region; designated as one of the world’s 11 biodiversity ‘hyper-hot’ hotspots (brookes et al., 2002) in requiring extensive conservation investment. however, large portion of the wet zone consists of human managed ecosystems such as agricultural lands, plantation forests and human settlements (ashton et al., 1995; pemadasa, 1996; bambaradeniya et al., 2004). therefore, the importance of such managed ecosystems cannot be overlooked. the habitat quality and subsequently the richness and abundance of naturally occurring species in such managed ecosystems can be improved further through planned management. this will not only help biodiversity conservation but also improve the productivity of these ecosystems through stabilizing natural processes such as nutrient recycling, pollination, soil conservation and control of pest populations. vast extents of sri lanka's biodiversity rich lands that were transformed into mono-crop plantations during the colonial era are regenerating in many places due to various natural and anthropogenic causes. bangamukande estate, which is situated in pitigala, galle, sri lanka (06 0 20' 46" n 080 0 16' 26" e 06 0 20' 46" n and 080 0 16' 26" e ) is an example for a plantation land of 18 hectares consisted of tea, rubber and cinnamon crops that has been deliberately reclaimed as an analog forest as a direct result of the far sighted land use policy of sri lanka during 1970 -1977, which introduced crop diversification in uneconomic tea plantations. the land is formed into an undulating terrain that consists of a series of ridges and valleys with an altitudinal range from 100m to 300m. in 1904, ancestors of the present owner planted agricultural mono-crops such as cinnamon, rubber, and tea and continued the cultivation practices until 12 hectares of cinnamon and tea land were transferred to analog forest using a government subsidy, under crop diversification of uneconomic tea lands in 1973. the remaining rubber field of 6 hectares is presently been allowed to regenerate into forestland while been cropped (wimalasuriya, 2006). analog forest is a tree-dominated ecosystem that is analogous in structure and function to the original climax and sub-climax community. with time, the natural succession of any undisturbed forest community is to increase in diversity and stability until a highly complex ecosystem or climax state is reached. when an ecosystem is designed to mimic the indigenous climax state, the efficiency and dynamics of the natural processes can be replicated; such forests are referred to as analog forests. as well to their ecological distinctiveness, analog forests are considered to provide economic benefits (liyanage et al., 2009 b ) a wide range of supplies can be produced that may include: fruit, nuts, herbs, cut flowers and cut-foliage, pharmaceuticals, timber and bees honey. the trees and plants in an analog forest will be similar to those in native ecosystems (liyanage, 2009). they will provide food or microhabitat for native species, but can also supply human needs (senanayake, 2000; liyanage et al., 2007). therefore, this system helps to develop environmentally friendly income generation which is described as green employment in the rural areas of the country (liyanage, 2009; liyanage et al., 2009 b ). this paper discusses about the potential to develop the rural green economy as a result of consolidating these agricultural lands into analog forests as a sustainable land use practice in a participatory approach model. 2. materials and methods two grama niladhari (gn) divisions named bangamukande and liyanagamakande belongs to niyagama divisional secretariat division in galle district were included forthis projec (figure 1, table 1). the terrain is mostly mountainous and is about 100m 600m above msl situated in the south western low land wet zone of sri lanka. the average temperature in the area is 27 o c, with an annual rainfall of between 3500mm 4500mm. liyanage et al., /journal of tropical forestry and environment vol. 3, no. 01 (2013) 9-16 11 figure 1: location of bangamukande and liyanagamakande with the surrounding forsted areas (source: google earth) two community based organizations (cbos) were formed in each gn division which were gathered at the village temple and chief buddhist monk in the temple acted as the patron since the total population in the area are buddhists. two awareness programs were conducted in the fields of ecofriendly farming activities and the importance of the conservation of biodiversity in the area to increase their knowledge about analog forestry, biodiversity and its importance. furthermore it included importance about crop diversification and long term impact from mono-crop cultivation. table 1: detailed locality of analog forest establishment including gn divisions gn division gps location height above msl liyanagamakande 080 0 16' 53.9" e 06 0 19' 86.2" n 080 0 16' 41.6" e 06 0 20' 17.5" n 147 m bangamukande 080 0 16' 25.9" e 06 0 20' 45.5" n 080 0 16' 39.9" e 06 0 20' 15.7" n 120 m lands including home gardens, private plantations, stream reserves, road reserves, temples lands and school gardens were selected for the project. several tree planting campaigns were organized with the help of the cbos. suitable plants were selected according to the topography of the land, type of the crop and the requirements of the land owners. timber plants, medicinal plants, fruit plants, food plants, shade plants, bamboo plants for the river-banks and some threatened endemic plants were selected for planting (appendix 1). timber plants were also distributed among the villagers of surrounding areas to plant in their home gardens which are located out of the forest corridor. bee keeping boxes were distributed among 30 selected villagers who were very keen to participate in this project component. the programme was started in year 2002 and still continuing. liyanage et al., /journal of tropical forestry and environment vol. 3, no. 01 (2013) 12-19 12 the progress of the project was monitored by conducting field visits and interviewing people of the area. one socio-economic survey was done at the begining of the year 2002 when conducting field visits for site selection. another two surveys were conducted in 2006 and 2008 to gain information on social mobilization of the project. 3. results a total of 4500 plants belonged to 35 species were planted so far in the forest corridor by this ongoing project, including 10 edible fruit plant species, 16 timber plant species and 10 medicinal plant species (appendix 1). according to the monitoring results, the plants are growing well since the ecological conditions of the region are favorable to those species. however the survival rate of the plants was approximately 68% and replanting was also occurred for filling the gaps. some plants in the selected list for planting activities provide nectar for honey bees. in addition there are many flowering wild plants in the area which bees are using for nectar. even though hunting of many wild animal species is prohibited in sri lanka, it happens illegally. before the project begins there were 12 hunters in the area and lot of wild animals such as sambur (cervus unicolor), purple faced leaf monkey (semnopithecus vetulus), porcupine (hystrix indica), pangolin (manis crassicaudata), wild boar (sus scrofa) and hare (lepus nigricollis) etc. were faced to threat of illegal hunting. however as a result of increasing awareness of the people about the importance of biodiversity for sustainable ecosystem, the illegal hunting was reduced about 92%. also the illegal encroachments of the forested lands were completely stopped as since 2003, there was no any encroachment reported (table 2). before 2002 the illegal felling of trees from the surrounding forested lands was about 176 trees/ year. when it comes to 2006, the illegal felling rate was reduced by 84% and by 94% and 98% in 2008 and 2011 respectively (table 2). table 2: summary of information obtained from pre and post socio-economic survey (reduction % is given in brackets) socio-economic factor 2002 2006 2008 2011 no. of persons engaged in illegal hunting 12 6 (50.00) 1 (91.67) 1 (91.67) illegal encroachments reported (ha/ year) 4.25 0 (100.00) 0 (100.00) 0 (100.00) illegal felling (tress/ year) 16 29 (8.52) 10 94.32) 3 (98.30) the introduction of new sustainable agricultural activities, such as bee keeping and planting fruits resulted in the production of value added farm products and organic fruits to be sold in the market. through environmental based tourism activities such as providing accommodation, eco guidance, selling food and fruit for local and international tourists, stakeholders are earning a better extra income. table 3 shows the development of green employment in the area. table 3: no. of people engaged in various green employment activities in the study area green employments 2002 2008 2011 bee keeping 2 45 52 fruit farmers 1 10 14 medicinal herb collectors 10 15 13 toddy tapping 5 12 10 ecological research assistants 0 4 6 eco tourism 0 10 15 liyanage et al., /journal of tropical forestry and environment vol. 3, no. 01 (2013) 9-16 13 4. discussion 4.1 increasing forest cover in the area while much community based re-forestation projects exist, only a few of them are designed to address the need of timber for construction and firewood, by the villagers, while concurrently establishing a corridor to move wild animals. the analog forest restoration in this project is both economic and ecological. it provides an alternative income to the participants while buffers the primary forests from activities such as logging, and the collecting of medicinal plants and fire wood, since the villagers are able to use the multipurpose analog forest area for these purposes. establishing of timber plants in their home gardens will ensure them to obtain their future timber requirements, without having encroachment to the forested areas and consequently help to conserve the forest indirectly. the project also results in the creation of a passage for the movement of animals from one forest patch to another, which will help to reduce inbreeding depression among animals. in this sense, the program was an effort towards habitat enrichment with the view of serving both human and wildlife needs. over a long term, this approach would be successful and cost-effective, unlike the attempt at implementing punitive measures, which has failed so far. 4.2 social impact of the program the participation of the villagers in the programme proved to be highly satisfactorily, and the encouragement given to the people to take part in this project was resulted in their active participation in many components of this project. the target group of the environmental awareness programmes done for each cbos were school children, village farmers and house wives who are active in dayaka sabhas in village temple. through education and awareness programs, the local community was assisted in accessing science and technology for their everyday life. the school children were more effective to take the conservation message to the public. they showed their active participation in planting activities in community areas and reservations throughout the project. the female community in the villages joined to the temple dayaka sabha or women’s society (mahila samithiaya), were another effective group for awareness activities as they showed their utmost interest in planting fruit and food plants as well as forest plants in their home gardens. therefore, students and female community should be considered as a target group in priority when planning any conservation activity or awareness programme. 4.3 emerging new paths for green employment development and poverty alleviation are very important for any sustainable project. this project helped to stabilize the economy of the local farmers and minimize the current environmental impact that resulted from mono-crop cultivation. crop diversification helped stabilize the economy of the local farmers. some stakeholders have made bee keeping boxes following the model of the distributed bee keeping boxes and increased their production of bee honey, could be considered as a multiplier effect of the programme. the flowering seasons of the trees existing in the area and established by the project are overlapping and continue year round, hence the bee keeping could be managed in a sustainable manner. a set of plants which was considered for this purpose is given in appendix 2 with their flowering seasons. bee keeping helps to enhance insect pollination, which leads to the protection of plant diversity. in addition, villagers will obtain an extra income from the sale of the bee honey, which is a non-timber forest product. 5. conclusion degraded soil conditions, low productivity from cash crops, lack of water retention capacity of the soil are having a direct impact on the local family income. through analog forest restorations the pattern is to be reversed by increasing the forest cover which will naturally regenerate the area with suitable bio liyanage et al., /journal of tropical forestry and environment vol. 3, no. 01 (2013) 12-19 14 diverse habitats allowing animal passage between these lands to the protected areas. therefore this concept can be used to link the fragmented forest patches in the wet zone of sri lanka. the planting activities and the increasing of the tree canopy of the area by this project has satisfied recommendations of the gap analysis programme of the protected area management project conducted in sri lanka in 2006. in addition, the project addressed a range of fields such as community mobilization, changing of farming activities from mono-crop cultivation to crop diversification, making of strategies for future sustainability of the project by establishing nurseries, educating of the younger generation on environmental issues and the surveying of the biodiversity in the area. it also addressed the taking of measures on poverty alleviation related programs such as promoting organic crops, bee keeping, and introducing other eco friendly income generators which trend to a sustainable development of the society. as well to their ecological distinctiveness, analog forests are considered to provide economic benefits. non timber forest products are biological products and services, derived mainly from forests ecosystems, and used to make different products for domestic use or marketing. the products such as food, beverages, fodder, fuel, medicine, fibers, bio-chemicals, fur, feathers, bees honey and wax are the value added natural products could be obtained from the analog forest ecosystem. non timber forest products are more important that timber products as these industries will not harm to the environment, which was agreed with godoy and bawa, (1993). emerging new economic initiatives such as carbon trading and ecotourism has paved the way to ensure higher economic benefits by converting some of the less productive agro ecosystems to semi-natural ecosystems. therefore, analog forest ecosystem plays a major role in enhancing the development of the rural green economy of sri lanka. acknowledgements mr. sunil wimalasuriya, mr. dulan ranga widanapathirana, mr. sarath rajapaksha, mr. vidupa rathnayaka and mr. piyasena gunasekara for their tremendous support in field work and the financial assistance provided by ministry of environment, sri lanka and the china scholarship council are acknowledged. references ashton, s.m., gunatileke s., de zoysa n., dassanayake m.d., gunatilake n., wijesundera s., 1995. a field guide to the common trees and shrubs of sri lanka. wildlife heritage trust of sri lanka. 5 cotta road, colombo, sri lanka. 431 pp. bambaradeniya, c.n.b., edirisinghe j.p., de silva d.n., gunatilleke c.v.s., ranawana k.b., wijekoon s., 2004. biodiversity associated with an irrigated rice agro-ecosystem in sri lanka. biodiversity and conservation 13: 1715-1753. brookes, t.m., mittermeier r.a., mittermeier c.g., da fonseca g.a.b., rylands a.b., konstant w.r., flick p., pilgrim j., oldfield s., magin g., hilton-taylor c., 2002. habitat loss and extinction in the hotspots of biodiversity. conservation biology 16(4): 909-923. earles, r., 2005. sustainable agriculture: an introduction publication of attra, the national sustainable agriculture information service. usa. gamage s.n., weerakoon d.k., gunawardena a., 2006. can agro-ecosystems function as alternates to natural habitats and link natural habitat patches; a case study of vertebrate diversity in three selected agro-ecosystems in southwestern sri lanka. proceedings of the international conference on humid tropical ecosystems, kandy, sri lanka. gamage s.n., liyanage w.k.d.d., wimalasuriya s., gunawardena a., 2007 a . vertebrates diversity in the 30 years of old analog forest in the pitigala, elpitiya. ruhuna journal of science. faculty of science, university of ruhuna, sri lanka (1) 162-177. liyanage et al., /journal of tropical forestry and environment vol. 3, no. 01 (2013) 9-16 15 gamage s.n., weerakoon d.k., liyanage w.k.d.d., wimalasuriya s.h., gunawardena a., 2007 b . participatory approach of establishing/consolidating forest corridors: a case study of the (ongoing ‘lorris’) participatory analog forest corridor in the wet zone of sri lanka. eco-summit 2007, beijing, p.r. china. godoy, r., bawa, k.s., 1993. the economic value and sustainable harvest of plants and animals from the tropical rain forest: assumptions, hypothesis and methods. economic botany. 47:215-219. liyanage, w.k.d.d., xulong, l., gamage, s.n., weerakoon, d.k., 2007. vertebrate diversity of a regenerated forest in south-western wet zone of sri lanka with special reference to avifauna. journal of environmental research and development 2(1): 6-19. liyanage, w.k.d.d., gamage, s.n., xulong, l., burnet, j.e., 2009 a . analog forest’s contribution to biodiversity conservation; a biodiversity assessment of an analog forest on a private property in southwestern wet zone of sri lanka. journal of american science 5(2): 69-82. liyanage, w.k.d.d., gamage, s.n., kumara, g.d.c.p., wimalasuriya, s., xulong, l., 2009 b . analog forest eco-system as a sustainable land use for development of rural green economy; an experience from south western wet zone of sri lanka. in proceeding of the ersec international conference on sustainable land use and ecosystem conservation, may, 2009, beijing, p.r. china. unesco, beijing. pp. 79-88. liyanage, w.k.d.d, 2009. assessment of the suitability of an analog forest as a viable biodiversity conservation option in highly fragmented landscapes in the southwestern wet zone of sri lanka. phd. dissertation. china university of geosciences (wuhan), p.r. china. pp.126. nekaris, k.a.i., troni, p., liyanage, w.k.d.d., 2004. conserving sri lanka's rain forests via conservation education in bangamukanda, galle district. folia primatologica. 75 (suppl 1): 399 (abstract) pemadasa, m.a. (1996) the green mantle of sri lanka. national library services board, sri lanka. 242 pp. scherr, s.j. and s. shames, (2006). agriculture: a threat or promise for biodiversity conservation. arborvitæ, the iucn/wwf forest conservation newsletter. senanayake, r. (2000) analog forestry; an alternative for clear and simplify. ileia newsletter september, 2000. 12-13. wimalasuriya, s.h. (2006) resurrecting razed rainforests. part 1. wimalasuriya property developers, colombo, sri lanka. 35 pp. appendix 1: list of plant species and the amount established in the analog forests name of the plant species usage no. of plants established rambutan (nephelium lappaceum) edible fruit 200 wal jambu (syzygium aqueum) edible fruit 50 jambu (syzygium malaccensis) edible fruit 100 goraka (garcinia quaesita) fruit/ spice 50 mangosteen (garcinia mangostana) edible fruit 100 aligeta-pera (persea americana) edible fruit 100 del (artocarpus altilis) edible fruit 100 jak fruit (artocarpus heterophyllus) edible fruit/timber 250 etamba (mangifera zeylanica) edible fruit/timber 50 coconut (cocos nucifera) edible fruit/timber 100 nedun (pericopsis mooniana) timber 350 mahogany (swietenia macrophylla) timber 600 bu-hora (dipterocarpus hispidus) timber 50 hora (dipterocarpus zeylanicus) timber 50 eeriya (enicosanthum acuminatum) timber 50 walukeena (calophyllum bracteatum) timber 50 liyanage et al., /journal of tropical forestry and environment vol. 3, no. 01 (2013) 12-19 16 batukeena (calophyllum thwaitesii) timber 50 hedawaka (cheatocarpus coriaceus) timber 50 milla (vitex altissima) timber 100 pihimbiya (filicium decipiens) timber 150 diya-naa (mesua thwaitesii) timber 100 naa (mesua ferrea) timber/medicinal 50 wenivel (coscinium penistratum) medicinal 100 sudu handun (santalum album) medicinal 200 kekiriwara (schumacheria castanaefolia) medicinal 100 ankenda (acronychia pedunculata) medicinal 150 pinibaru (lijndenia capitella) medicinal 50 ruk (horsfieldia iryghedi) medicinal 200 welipiyanna (anisophyllea cinnamomoides) medicinal 50 keta-kela (bridelia retusa) medicinal 100 kebella (aporosa lindleyana) medicinal 50 walla patta (gyrinops walla) handicraft 50 kitul (caryota urens) traeckle/jaggery/toddy 100 puwak (areca catechu) medicinal/chewing/boundary demarcation 200 bamboo (bambusa spp.) river bank conservation/ timber 400 total plants established 4500 appendix 2: plants producing nectar for honey bees showing their flowering calendar plant species j a n u a r y f e b r u a r y m a r c h a p r il m a y j u n e j u ly a u g u st s e p te m b e r o c to b e r n o v e m b e r d e c e m b e r cocos nucifera artocarpus heterophyllus coscinium penestratum schumacheria castanaefolia caryota urens areca catechu fahrenheitia zelanicas acronychia pedunculata hevea braziliensis harpullia arborea elaeocarpus serratus vitex altissima prunus walkeri calophyllum trapazifolium mangifera zaylanica mesua thwaitesii mesua ferrea symplocos cochinchinensis bridelia retusa shorea megistophylla dipterocarpus gardneri horsfieldia tryghedi stemonoporus canaliculatus perera et al. /journal of tropical forestry and environment vol. 07, no. 01 (2017) 1-14 1 feature article pangolins (manis crassicaudata) in sri lanka: a review of current knowledge, threats and research priorities p.k.p. perera*, k.v.d.h.r. karawita and m.g.t. pabasara department of forestry and environmental science, university of sri jayewardenepura, nugegoda, sri lanka abstract the indian pangolin (manis crassicaudata) is arguably the least studied species of all asiatic pangolin species and, is the solitary pangolin species recorded in sri lanka. growing concerns over their population decline due to poaching and trading has triggered a move to uplift indian pangolin to appendix i of the convention on international trade in endangered species of wild fauna and flora (cites). however, lack of reliable scientific information on the behavior, ecology and threats for the survival of indian pangolin remains a major limitation in conservation of the species. this narrative review discusses the current knowledge on indian pangolin with special reference to sri lanka, and identifies key research priorities for better conservation planning of the species. key words: indian pangolin, trading, poaching, conservation, ecology, behaviour 1. introduction pangolins are unique mammals of the family manidae (gray, 1821) in the order pholidota (weber, 1904). pangolins are also known as “scaly anteaters” because of the presence of keratinized plate-like protective scales covering most part of their bodies, and their highly specialized diet which predominantly consist of ants and termites. eight different pangolin species have been described from afro-tropical and indo-malayan regions of the world (gaubert and antunes, 2005). based on the geographic distribution, pangolin species are broadly categorized into two groups; african pangolins and asian pangolins. four pangolin species are restricted to asia; chinese pangolin (manis pentadactyla), sunda pangolin (manis javanica), indian pangolin (manis crassicaudata) and philippine pangolin (manis culionensis). pangolins are at a greater conservation risk due to excessive hunting and poaching, and they may be the most illegally trafficked group of mammals in the world (challender, 2013; aisher, 2016) . out of the four asiatic pangolin species, m. pentadactyla and m. javanica have been categorized as critically endangered, while the other two asiatic pangolin species have been listed as endangered by the international union for conservation of nature (iucn, 2016). all eight pangolin species have been recently included in the appendix i of the convention on international trade in endangered species of wild fauna and flora, where international trading for commercial purposes of listed species is strictly prohibited (cites, 2016). 2. about the indian pangolin among all asian pangolin species, indian pangolin may be the least studied species (mahmood et al., 2014). it is the only pangolin species recorded in sri lanka. in sinhalese it is commonly called ‘aeya’ or ‘kaballewa’, and in tamil it is referred to as ‘alangu’. indian pangolin has been considered as an iconic species with a cultural significance in sri lankan tradition and history. *correspondence: priyan@sjp.ac.lk tel: +94-112758411, fax: +94 112803470 issn 2235-9370 print / issn 2235-9362 online ©2017 university of sri jayewardenepura perera et al. /journal of tropical forestry and environment vol. 07, no. 01 (2017) 1-14 2 morphology and behavior also known as the thick-tailed pangolin, m. crassicaudata is a medium-sized mammal that has an elongated tapering body covered with large overlapping scales. scales are absent on ventral side of the body, head, inner surfaces of limbs and foot pads (heath, 1995). these moveable scales are shedded periodically. the number and the pattern of scales may show intraspecific variations (heath, 1995; kaspal, 2010). according to published descriptions, the number of rows of body scales can vary from 11 to 18 (kaspal, 2010; prater, 1980). the colour of scales varies from shades of brown to yellow, and often depends on the colour of the soil associated with the habitat of the animal. the terminal scale on the ventral side of the prehensile tail of the indian pangolin is a distinct feature to differentiate them from other pangolin species (heath, 1995). unlike most mammals, hair is virtually absent on dorsal surface of pangolins except some thick, short hair present in between scales. however, thin, long, light coloured hairs are present on the bare parts underneath (kotagama and goonatilake, 2013). indian pangolins are largely fossorial, but they are swift climbers as well. while walking on the ground, the tail and trunk are kept parallel to the ground with the back slightly arched (figure 1a). the hind legs are used to stand upright and search or sniff the surrounding air to detect prey (israel et al., 1987). indian pangolin’s forelegs are specifically adapted for burrowing and digging. the three central claws are long and slightly curved (figure 1c). when climbing, forelimbs are used to tightly grip the tree, while the hind limbs are used to push the body upwards, and the tail helps to balance when arboreal (prater, 1980). the indian pangolin can quickly roll itself into a compact ball in self-defense, exposing only its scales to a predator (figure 1b), and hissing loudly to scare off the predator. it can secrete a fluid with an irritating odor from their anal glands when disturbed or distressed by predators or humans (roberts, 1997). figure 1: the indian pangolin (a) adult male walking on the ground (b) a rolled-up pangolin showing its defensive behaviour (c) forelimbs of pangolin with sharp claws indian pangolin is myrmecophagous and thus has unique anatomical adaptations to pray on ants and termites (yang et al., 2007). these adaptations include a conical‐shaped head, absence of teeth, a long sticky flexible tongue and robust forelimbs with enlarged claws for procuring and eating ants and termites perera et al. /journal of tropical forestry and environment vol. 07, no. 01 (2017) 1-14 3 (swart et al., 1999, botha and gaudin, 2007, atkins, 2004). morpho-anatomical studies of indian pangolin have revealed that the length of the tongue of an adult indian pangolin can be up to 37% of the body length, and the average length of the tongue of an adult is about 42.5cm (chakkaravarthy, 2012; irshad et al., 2016). indian pangolins have poor eyesight, but they have a highly-developed olfactory senses to detect their prey as well as predators (israel et al., 1987). the indian pangolins are nocturnal animals and they sleep during the day in burrows, hollows or dens. their activities are mostly recorded in the night (dickman and richer, 2001). they are solitary mammals and seldom seen in groups. males are substantially larger than females at the same maturity. their breeding ecology and behavior is poorly understood. indian pangolins usually give birth to one offspring and rarely the litter size can be up to two (prater, 1980; israel et al., 1987). the female carries its newborn on the dorsal base of the tail. the mother coils her body, taking the cub into the center of the coil when she feels the cub is insecure (heath, 1995). distribution indian pangolin naturally occurs in larger part of south asia (figure 2) and its geographic range extends from eastern pakistan through much of india (excluding northeastern parts), bangladesh, sri lanka, nepal, and up to myanmar (wilson and reeder, 2005; mishra and panda, 2012). some indian pangolin populations have also been recorded from southwest china (roberts and vielliard, 1971). the indian pangolin is known to inhabit various habitat types. in eastern pakistan, the species have been recorded from arid grasslands, deserts and barren hilly areas up to 2300 feet above mean sea level (mahmood et al., 2012; mahmood et al., 2014). in india, it shows a wide distribution from south of india to southern lower hills of the himalayas, covering an array of natural and manmade habitats including tropical rain forests, subtropical thorn forests, deciduous forests, open scrub lands, grasslands, cultivated lands and in association with human settlements (chakkaravarthy, 2012). in nepal, the species has been recorded particularly from lowlands to the south and west of the country (baillie et al., 2014). indian pangolin populations in bangladesh, china and myanmar may be very small (khan, 1985) or possibly extinct (baillie et al., 2014). figure 2: distribution of the indian pangolin m. crassicaudata in sri lanka, m. crassicaudata is the solitary species belonging to order pholidota and it has been recorded from throughout the lowlands up to 1,100m above mean sea level with their distribution often perera et al. /journal of tropical forestry and environment vol. 07, no. 01 (2017) 1-14 4 coinciding with the range of termites (phillips, 1981). they are of variable abundance in sri lanka, with few known locations in both wet and dry zones of the country where pangolins are rather frequently encountered or regularly caught by locals (pabasara et al., 2015; karawita et al., 2016). however, no records of the abundance and population numbers are available, and the species is rarely observed due to its secretive, solitary, and nocturnal habits. 3. current knowledge on the ecology of indian pangolins owing to its nocturnal, illusive behavior, the autecology of indian pangolin remains poorly understood compared to other asiatic pangolin species (mahmood et al., 2014). limited studies in literature have investigated the autecology of indian pangolins, and a review of current knowledge on the ecology of indian pangolins is provided herein. habitat characterization and preferences the indian pangolin occupies a variety of habitats in its geographical range, and an understanding of its habitat characteristics, habitat preferences, and habitat utilization patterns in different environments is vital for conservation planning of the species. published ecological studies suggest that the indian pangolin is capable of adapting to different environments across it’s rang. habitat features such as tree species composition, vegetation cover and geological features (such as presence rock boulders, water sources, and soil characteristics) are important parameters worth considering in habitat characterization (wu et al., 2003; mahmood et al., 2014; pabasara et al., 2015). the indian pangolin inhabits different types of tropical forests including wet evergreen forests, moist forests, dry deciduous, thorn and scrub forests, and grasslands up to mid-elevations (chakkaravarthy, 2012). it is also recorded from degraded wastelands and agricultural lands near human habitations. a study on the habitat preference of indian pangolins in open barren areas of potohar plateau, north-eastern pakistan reported that pangolin barrows tend to be specifically associated with certain tree or shrub species such as ziziphus mauritiana, acacia nilotica, and zizyphus nummularia (mahmood et al., 2014). in a comparative study of four habitat types (i.e. secondary natural forest, pine-dominated forest, rubber plantations and tea-dominated home gardens) associated with a tropical lowland wet evergreen rainforest in southwest sri lanka, pabasara et al. (2015) observed that evidences for the presence of pangolins is highest in pine-dominated forest. this observation was explained by the greater abundance of prey i.e. termites and ants in pine-dominated forest where dead and decaying wood logs were more abundant. the same study found that medium slope, low undergrowth, dense canopy closure and presence of rock boulders as the most common habitat features associated with pangolin burrows. a recent study by mahmood et al. (2013) suggests that the indian pangolin digs two types of burrows; living burrows and feeding burrows. parameters such as barrow depth and diameter as well as the presence of remains of prey items and presence of fecal matter are considered as important signs in distinguishing the two types of pangolin barrows (irshad et al., 2015). during the day time, pangolins sleep curled inside a “living burrow”, which may have several outlets sealed with loose earth (prater, 1980). burrows are usually made under large rock boulders or sometimes in tree bases. the depth of the burrow varies depending on the soil type; 1.5 to 2m in rocky soils, and up to 5m or more in loose soil (prater, 1965). by comparing the total number of inactive and active living burrows, mahmood et al. (2013) concluded that the indian pangolin usually abandons its living burrow after a few months of use, and digs a new one probably within its home range which often overlaps with the distribution and abundance of its pray. re-occupying an older living burrow is also possible within the same year (mahmood et al., 2013). feeding burrows in contrast, are significantly lesser in depth (often less than 1m) and have smaller openings compared to living burrows (mahmood et al., 2013, pabasara et al., 2015). perera et al. /journal of tropical forestry and environment vol. 07, no. 01 (2017) 1-14 5 feeding ecology for the purposes of this review, feeding ecology is defined as the processes which determine general diet of the species including prey selection. when describing the feeding ecology of indian pangolins, it is essential to have an assessment of their diet. this may be achieved by analysing prey species and remains found in or around feeding burrows, analysis of stomach contents or analysing the undigested prey remains in faeces. an investigation conducted using fecal analysis of indian pangolins in four districts of potohar plateau, pakistan by irshad et al. (2015) found that ants (camponotus confusion, camponotus compresses) are the major prey of indian pangolin in the studied habitat while termites (odontotermis obesus), bugs, wood fibers and grasses constituted other major components of the diet. this study further identified clay and soil particles as the most voluminous components of fecal samples, accounting for about 48% to 62% of the fecal matter respectively. the passive intake of soil and clay particles is considered to aid in the mechanical digestion process inside the stomach where there is virtually no mechanical digestion takes place in the oral cavity due to the absence of teeth. though considered as myrmecophagous, indian pangolins may oppertunistically feed on beetles, cockroaches, magotts and larvae of insects as revealed by gut content analysis studies (hutton, 1949; lekagul and mcneely, 1977; heath, 1995; mahmood et al., 2013) and according to local knowledge (pabasara et al., 2015; karawita et al., 2016). the eggs of the ants are more preferred by the indian pangolins over ants, and they prefer feeding on prey found by burrowing rather than the prey species fond on the soil or rock surfaces (heath, 1995). some observations report that captive indian pangolins refused feeding on red ants and termites, and showed a specific liking to feed on the black ants (mohapatra and panda, 2014b). indian pangolin has highly specialized feeding habits. they feed mainly on eggs, nymphs and adults of termites and ants by digging the termite or ant nests (mohapatra and panda, 2014b). before digging the termite or ant nests, they use their highly developed olfactory organs to rapidly sniff around the area to determine the most suitable place of the nest to attack. when digging deep into or under mounds, they move out backwards to expel soil with their forefeet. hind legs are used to throw loose soil backwards. the animal feed rapidly by extending the long protrusible tongue into the galleries of nests (payne and francis, 1998 ). the rostral part of the tongue is quickly inserted and withdrawn to capture prey. this movement is also used in drinking (mohapatra and panda, 2014a). due to the absence of teeth, food is directly taken into the stomach and subjected to mechanical grinding. abundance, population estimates and trends there is insufficient information available on population levels of all asiatic pangolin species (baillie et al., 2014). only a handful of studies have attempted to estimate the abundance and population size of indian pangolins. for instance, mahmood et al. (2014) estimated the population size of indian pangolins in the district of chakwal in potohar plateau, pakistan by counting the active living burrows of indian pangolins along established transects. their study reported a population density of 0.067 individuals per km2. a survey in the same study area has further documented a rapid population decline due to illegal mass killing of indian pangolins for their flesh and scales (mahmood et al., 2012). in contrast, a study conducted by pabasara (2016) to assess the abundance of indian pangolin in yagirala forest reserve; an isolated patch of tropical lowland rainforest in south-west sri lanka reported a population density of 5.69 individuals per km2. this study employed camera trapping techniques, and the population estimate was based on the model described by rowcliffe et al. (2008). the population density of indian pangolins reported by pabasara (2016) is considerably higher than mahmood et al. (2014)’s estimate. this discrepancy may be due to the differences in habitats where tropical rainforests being more diverse and abundant in terms of prey species of indian pangolin, or may be due to the different methodological approaches used. pabasara (2016) also used photographic records to estimate the abundance of indian pangolins with “occurrence index” described in shek et al (2007). a survey of perera et al. /journal of tropical forestry and environment vol. 07, no. 01 (2017) 1-14 6 local hunters and the community in yagirala forest surroundings by karawita et al. (2016) has further reported concerns over alarming exploitation levels of indian pangolins, potentially leading to decline of the local population of indian pangolins. although several other published works indicate a negative trend in the population levels of indian pangolins across its geographical range (baillie et al., 2015; challender et al., 2015), lack of scientific studies on population estimates continues to be a significant hindrance in assessing its conservation needs. husbandry and behavior in captivity the history of attempts on captive management and husbandry of indian pangolins dates back to 1892 (sanyal, 1892), yet there is a lack of scientific knowledge on the best practices of captive management of indian pangolins. numerous attempts have been made to raise india pangolins in captivity, particularly in zoos. according to yang et al. (2007), rearing indian pangolin in captivity have been attempted between years 1941 to 1970 in zoos of jaipur, simba, calcutta, ahmedabad and madras in india, dehiwala zoo in colombo, sri lanka, antwerp zoo in belgium, wilhelma zoo in stuttgart, germany, prague zoological garden in prague, the czech republic, zoos of detroit, pittsburgh, st. louis, chicago brookfield, miami crandon park, oklahoma, mesker park zoo in indiana, and milwaukee zoo in wisconsin in the us. however, most of such attempts have failed to maintain the animals for longer periods. dietary problems and stress have been often cited as the major causes of mortality of indian pangolins under captive conditions (yang et al., 2007; pattnaik, 2008). for instance, a captive rearing attempt of indian pangolin has been recorded from oklahoma city zoo, usa in 1965 (ogilvie and bridgwater, 1967). a pair of indian pangolins captured from gadani an area closer to karachi, pakistan was shipped to the oklahoma city zoo. the animals have been fed with a diet consisting of horse meat, dog feed, evaporated canned milk, eggs, a mixture of vitamin a, b, c, d, and e with parts of decaying logs to lure them to feed on the captive diet. animals have been housed in a room measuring 2.4m × 3.0m with the floor covered with wheat straw or hay. according to the notes of ogilvie and bridgwater (1967), pangolins had shown a behavior of deliberate addition of litter to the body coil before they sleep on the floor. the male pangolin became weaker due to rejection of food and was suffering from severe infection beneath the dorsal scales. the male pangolin did not survive even a month in captivity. the postmortem revealed that the larynx of the pangolin was clogged with a heavy mass of food and the death possibly caused due to suffocation. the female individual gave birth to one male cub within two months in captivity. mother cared the newborn by coiling around the cub. the newborn cub also died three days after the birth due to starvation. several other artificial diets have been used or suggested by various researchers in rearing indian pangolins in captivity (ramakantha, 1992, yadav, 1973). yet, the species may find it difficult to adapt to an artificial diet and even reject its regular live prey probably due to stress when kept in captive environments. according to published reports, the mortality rate of indian pangolins is 67-71% within the first year in captivity with only 11.5% living more than 2.5 years (lal-mohan, 1997; chakkaravarthy, 2012). the pangolin conservation breeding center (pcbc) of nandankanan biological park in india has been successful in husbandry and captive breeding of the indian pangolins, and has been in operation since 2008 (chakkaravarthy, 2012; mohapatra and panda, 2014a). at pcbc, pangolins are individually housed in 4.8 × 4.2 × 3.0m enclosures with 0.5m deep red laterite soil provided as substrate, and wooden logs and poles provided as enrichment materials. the enclosure design further consists of reinforced concrete walls on all four sides up to a height of 1.0m and chain-link mesh netting provided on all four sides above the level of concrete base to facilitate proper ventilation and natural sunlight. considering the success of the program, the enclosure design, daily husbandry routine, diet and veterinary care procedures used at pcbc may provide useful guidelines for future captive breeding efforts. captive behaviors of indian pangolin have been also investigated at the pcbc using cctv (close circuit television) camera systems (mohapatra and panda, 2014a). some preliminary observations perera et al. /journal of tropical forestry and environment vol. 07, no. 01 (2017) 1-14 7 revealed that captive indian pangolins display the natural pattern of nocturnal activity with a peak activity period between 20:00 to 21:00 hours, while an intermittent level of activity has been recorded between 17:00-05:00 hours. during the period where they are active, a greater proportion of time is spent on walking in the enclosure while some individuals exhibited pacing behaviour in the shape of “8” or “o”. according to mohapatra and panda (2014a), indian pangolins prefer wet soil substrates for digging, and also seek shelter under hollow wooden logs placed inside the enclosure. 4. threats and conservation the indian pangolin is timid, inoffensive and rather a slow mover. it predominantly relies on ‘rolling-up’ mechanism for defense, and thus can easily fall prey to poachers. increased market demand for pangolin meat and scales has shifted hunting for local consumption to international trade, which in turn has intensified the exploitation of indian pangolin populations. traditional uses indian pangolin has been traditionally hunted by different tribal communities throughout its geographical range for variety of purposes; especially for ethno-medical uses. for instance, in india, some ethnic groups believe that scales and claws of indian pangolin possess antiseptic properties, and thus use pangolin claws to pierce boils or skin abscess, and ointments made of pangolin scales to heal wounds and inflammations (mohapatra et al., 2015). bile of the indian pangolins is used by some communities in arunachal pradesh of india to cure the splenomegaly (chinlampianga et al., 2013) while some forestdwelling tribes in orissa, india are known to wear rings made of indian pangolin scales as a remedy for piles/haemorrhoids (mishra and rout, 2009). indian pangolin scales are also believed to have nematocidal properties (betlu, 2013). in nepal, some communities consider pangolin flesh as a remedy for asthma and rheumatic fever, while oil extracted from pangolin scales is used to treat bone and muscle disorders (kaspal, 2010). pangolin scales are also used by tribal ethno-medical practitioners in treating infertility in women (katuwal et al., 2013). cultural and mythical beliefs of certain tribal communities have also caused indian pangolin populations to decline over the years in nepal. for instance, using pangolin scales in children’s’ jewelries is believed to protect them from evil spirits, and wearing pangolin scales is believed to bring luck (katuwal et al., 2013). in pakistan, traditional and ethno-medical practitioners also value pangolin body parts as ingredients for variety of traditional medicines (roberts, 1997). unlike in other countries where indian pangolin is native, evidences for using pangolin body parts for traditional ayurveda medicine are scarce or non-existent in sri lanka (karawita et al., 2016). instead, it has been long consumed as a bush-meat by local communities. for instance, ethno-archaeological studies on the subsistence patterns of the indigenous “vedda” community of sri lankan has revealed that the flesh of indian pangolins have been traditionally consumed by “vedda” community, and in hunting they have used smoke to drive pangolins out of the burrows (chandraratne, 2016). furthermore, bone parts of the indian pangolins have also been found from mesolithic explorations in “beli-lena”; a prehistoric cave in sri lanka (kajale, 2014). local and international trade indian pangolin at present is under severe hunting pressure due to local consumption and rising demand for its scales and meat in east asian markets, especially the chines markets (baillie et al., 2015; challender, 2011). according to expert observations, the virtual extirpation of m. pentadactyla and m. javanica in east asia is the major factor that drives the high demand for m. crassicaudata in international markets at present (baillie et al., 2004; challender, 2013; mohapatra et al., 2015). the indian pangolin populations in india and pakistan have been over-exploited for international trade with most smuggled specimens and parts ending up in chines and myanmar markets (baillie et al., 2015). according to a perera et al. /journal of tropical forestry and environment vol. 07, no. 01 (2017) 1-14 8 recent survey by mahmood et al. (2012), 118 indian pangolins have been killed for flesh and scales during the period from january 2011 to may 2012 in potohar region of pakistan alone, while an estimated 1,690 specimens of indian pangolin have been confiscated from illegal trade between 2009 and 2014 in india (mohapatra et al., 2015). in sri lanka, pangolin flesh is considered a delicacy by local hunters. as a result of excessive hunting, pangolins have been almost eliminated in areas where they stray into contact with people. unlike in other countries of the region, reported cases international trade of pangolin scales or specimens is very limited (karawita et al., 2016). hence, the major threat for their survival comes from local hunters. since year 2000 to june 2017, only three attempted cases of smuggling pangolin scales from sri lanka have been reported by the sri lanka customs; in 2012 and 2016 (figure 3). in all occasions, the offenders were trying to smuggle pangolin scales to india. however, these recent confiscations cannot be considered as isolated incidents, and may hint possible international trading of pangolin scales from the country in a much larger magnitude through multiple channels. figure 3: confiscated pangolin scales by biodiversity, cultural and national heritage protection division of sri lanka customs at the bandaranayake international airport, sri lanka (photograph: sri lanka customs, 2017) preliminary investigations by karawita et al. (2016) revealed the existence of possible niche local markets for pangolin meat where some restaurants catering predominantly for foreigners, have reportedly paid lucrative money to local hunters in supply of pangolin meat. nonetheless, such claims need further validation through in-depth studies. apart from poaching and hunting, rapid loss and deterioration of habitats, agricultural expansions, ad-hoc use of pesticides and road-kills are also cited as other threats for the survival of indian pangolin (chakkaravarthy, 2012; karawita et al., 2016). conservation populations levels of indian pangolin is believed to have a declining trend in all countries where it naturally occurs and, according to iucn projections, populations of this species will fall at least by 50% in the next 20 years, especially given the present high rate of exploitation (mahmood et al., 2012; baillie et al., 2014). their naturally low birth rate with female pangolins producing mostly one offspring a year has also contributed to the negative population trend (zhou et al., 2014). recognizing the high level of perera et al. /journal of tropical forestry and environment vol. 07, no. 01 (2017) 1-14 9 risk the species is faced with, m. crassicaudata has been listed as an endangered (en) species by the iucn (baillie et al., 2014). enabling greater protection from international trading, the species has been further transferred from appendix ii to appendix i of the convention on international trade in endangered species of wild fauna and flora (cites). the indian pangolin is listed under ‘near threatened’ (nt) category of the national red list of sri lanka (weerakoon, 2012). it is also included in the schedule ii of the flora and fauna protection ordinance (amendment) act no. 22 of 2009 of sri lanka. the schedule ii includes mammals and reptiles that are strictly protected by law. the department of wildlife conservation of sri lanka has further included indian pangolin among country’s five ‘most concerned’ animals (dwc, 2016). despite such strict protective legal measures, indian pangolins continue to be illegally captured and killed for local consumption in various parts of sri lanka. 5. future research priorities for sri lanka as highlighted in this review, only a few studies have been carried out on wild populations of indian pangolins across its range (table 1). these are localized studies carried out in few selected habitats or environments, and thus having location-specific information. given the wide variety of habitats that indian pangolins occupy, published data on population sizes and distribution are insufficient to enable an accurate assessment of their conservation needs. although habitat preferences, feeding ecology and behaviours of indian pangolin have been investigated elsewhere (table 1), there is still a dearth of information on the autecology of the species. in sri lanka, preliminary investigations on selected aspects of autecology of the indian pangolin have been attempted in a tropical lowland forest habitat (pabasara, 2016). other than that, no published studies on the ecology and population levels of m. crassicaudata is available in sri lanka. considering their high vulnerability and deficiency of population data, the indian pangolin should receive more conservation priority in sri lanka. hence studies on population abundance and autecology of indian pangolin are of greater importance in the sri lankan context. one of the major impediments in studying wild pangolins has been the difficulty in locating them. as such, standard ecological census and monitoring techniques may not be well suited for the detection and surveying of pangolins (newton et al., 2008). determining absolute densities of animals is complex and often controversial. for many species, however, direct counts are impractical and researchers may need to rely on indirect signs, such as tracks, scats or den sites (wilson and delahay, 2001). radio telemetry techniques are widely used in studying the ecology of wild animals as a cost-efficient method compared to gps tracking methods. such methods allow easy observation of the activity cycle, habitat preference, feeding grounds and resting places of the pangolins (norman, 2009). the potential of radiotracking wild-caught pangolins to monitor home-range size and habitat utilization has been demonstrated by previous works (heath and coulson, 1997; lim and ng, 2008; richer et al., 1997). in these studies, radio transmitters were tagged to the dorsal scales closer to the base of the tail of pangolins to minimize disturbances to their usual behaviors in the wild. for instance, lim and ng (2008) used a combination of radio-telemetry and infrared-triggered camera traps to study the home range, activity cycle and natal den usage of manis javanica. however, these radio-tracking studies have been conducted in areas with high pangolin densities. as indian pangolins are rapidly becoming nowhere common, development of field detection and monitoring methodologies applicable to habitats with low population densities will be of more relevance in future research. use of mixed methodologies may also be helpful in population studies of highly illusive species such as indian pangolins. for instance, newton et al. (2008) used local hunters’ knowledge to understand the distribution and abundance of pangolins (manis pentadactyla and m. javanica) in vietnam. camera trapping techniques have also been used to determine the distribution and abundance of pangolins (pabasara, 2016). in some cases, baits have been used to attract pangolins towards the camera trap (marler, 2016). perera et al. /journal of tropical forestry and environment vol. 07, no. 01 (2017) 1-14 10 table 1: recent studies on indian pangolin m. crassicaudata study scope recent studies range country information gaps and limitations research priority for sri lanka ecology, behavior and population distribution mahmood et al (2013); mahmood et al (2014); irshad, et al (2015); mahmood et al. (2015); mahmood et al (2016); akrim et al (2017) pakistan limited geographical coverage, highly localized studies under few selected habitats or environments limited and incomplete information available mishra and panda( 2012) india high priority pabasara et al. (2016) sri lanka trading, poaching and extraction mahmood et al. (2012) chakkaravarthy (2012); mohapatra, et al (2015); kumar, et al (2016) pakistan india findings are mainly based on secondary information and limited primary data obtained through case studies no published information available high priority community perceptions and awareness on conservation kaspal (2010) chakkaravarthy (2012) karawita et al (2016) nepal india sri lanka localized case studies limited and incomplete information available high priority captive behavior, conservation breeding and husbandry mohapatra and panda (2013); mohapatra and panda (2014a); mohapatra and panda (2014b); mohapatra, et al (2015) india studies conducted under variable captive environments with most studies reporting limited success in maintaining animals in captivity no published information available moderate priority genetics and biochemistry mathur and rathi (1966); aswathanarayana (2000); mohapatra et al (2014) india low priority anatomy and morphology irshad et al. (2016) pakistan low priority another major obstacle in assessing the conservation needs of m. crassicaudata in sri lanka is the absence of accurate information on hunting, poaching and extraction levels of the species. published data are mainly based on secondary information and limited primary data obtained through case studies. records on international trading of pangolins originated from sri lanka in the literature are scarce (challender et al., 2015). lack of public awareness on the conservation importance of indian pangolins, and rather low conservation priority given by officials over the years has contributed to the decline of indian pangolin population in the country. as the major threat for the survival of indian pangolins is from local communities, an understanding of public perceptions and awareness on pangolin conservation is important. communities and officials need to be aware of the importance and benefits of pangolin conservation so that they can be effectively involved in conservation measures based on participatory approaches (chakkaravarthy, 2012). as such, studies directed towards understanding the extraction levels (including possible local and international trading) of pangolins and local community awareness on pangolin conservation in sri lanka should be highly prioritized in the research agenda. upon the accurate assessment of current threats and population levels, ex-situ conservation programs such as rearing and breeding indian pangolins in captivity and reintroduction to their natural habitats may be required. such measures are often expensive and require technical expertise. however, most ex-situ conservation programs of indian pangolins have not been successful due to the poor understanding of dietary ecology and behavior of the species. as highlighted by previous researchers, comprehensive knowledge on the behaviour of indian pangolins under captive conditions is vital in perera et al. /journal of tropical forestry and environment vol. 07, no. 01 (2017) 1-14 11 rearing and management of animals for potential captive breeding programs (challender, 2009; mohapatra and panda, 2014a). cctv cameras have been successfully used in behavioral observations of captive indian pangolins (mohapatra and panda, 2014a) while infra-red triggered remote camera traps have been employed in captive behavioral studies of other illusive nocturnal mammals (jayaratna et al., 2015). however, in the sri lankan context, such ex-situ conservation measures can be identified as medium to long term actions, and of moderate research priority due to limited scientific information. instead, in-situ conservation measures should be prioritized. 6. conclusion indian pangolin remains as one of the least studied mammals in sri lanka and throughout its geographical range to a greater extent. indian pangolin populations are believed to be rapidly declining. hunting for local consumption along with habitat loss are the major causes for the decline of indian pangolin population in sri lanka. with the inclusion of indian pangolin to the appendix i of the cites during the 17th meeting of the conference of the parties held on october 2016, the interest on conservation of the species has increased. however, the dearth of scientific research on m. crassicaudata in the sri lankan context is a major concern in conservation planning of the species. this review identifies three research areas to prioritize in order to generate the essential information to assess conservation needs and in-situ conservation planning of m. crassicaudata i.e. (1) ecology, behavior and population abundance of indian pangolins (2) assessment of hunting/poaching/extraction levels of indian pangolins and (3) understand the community perceptions and awareness on conservation of indian pangolins. research focused on behavior in captivity, conservation breeding and husbandry of indian pangolins are of moderate research priority as these will predominantly generate information useful for ex-situ conservation measures. reference aisher, a. 2016. scarcity, alterity and value: decline of the pangolin, the world's most trafficked mammal. conservation and society, 14, 317. atkins, w. 2004. pholidota pangolins (manidae). grzimek's animal life encyclopedia. volume, 16. baillie, j., challender, d., kaspal, p., khatiwada, a., mohapatra, r. & nash, h. 2014. manis crassicaudata. the iucn red list of threatened species. baillie, j., challender, d., kaspal, p., khatiwada, a., mohapatra, r. & nash, h. 2015. manis crassicaudata. the iucn red list of threatened species. version. baillie, j., hilton-taylor, c. & stuart, s. n. 2004. 2004 iucn red list of threatened species: a global species assessment, iucn. betlu, a. l. s. 2013. indigenous knowledge of zootherapeutic use among the biate tribe of dima hasao district, assam, northeastern india. journal of ethnobiology and ethnomedicine, 9, 1. botha, j. & gaudin, t. 2007. an early pliocene pangolin (mammalia; pholidota) from langebaanweg, south africa. journal of vertebrate paleontology, 27, 484-491. chakkaravarthy, q. a. research and conservation needs of the indian pangolin (manis crassicaudata). proceedings of third seminar on small mammals conservation issues, 2012. 50-55. challender, d. asian pangolins: how behavioural research can contribute to their conservation. workshop on trade and conservation of pangolins native to south and southeast asia, 2009. 95. challender, d. 2011. asian pangolins: increasing affluence driving hunting pressure. traffic bulletin, 23, 92-93. challender, d. 2013. the most traded wild mammal-the pangolin-is being eaten to extinction. iucn. perera et al. /journal of tropical forestry and environment vol. 07, no. 01 (2017) 1-14 12 challender, d. w., harrop, s. r. & macmillan, d. c. 2015. understanding markets to conserve tradethreatened species in cites. biological conservation, 187, 249-259. chandraratne, r. 2016. some ethno-archaeological observations on the subsistence strategies of the veddas in sri lanka. chinlampianga, m., singh, r. k. & shukla, a. c. 2013. ethnozoological diversity of northeast india: empirical learning with traditional knowledge holders of mizoram and arunachal pradesh. indian journal of traditional knowledge, 12, 18-30. cites. 2016. consideration of proposals for amendmentof appendices i and ii [online]. available: https://cites.org/sites/default/files/eng/cop/17/prop/060216/e-cop17-prop-11.pdf [accessed 3 may 2017. dickman, c. r. & richer, r. a. 2001. pangolins. . the encyclopedia of mammals, d. w. macdonald eds. (new york: facts on file), 800-801. dwc, 2016. sri lanka's five most concerned. department of wildlife conservation,sri lanka. gaubert, p. & antunes, a. 2005. assessing the taxonomic status of the palawan pangolin manis culionensis (pholidota) using discrete morphological characters. journal of mammalogy, 86, 10681074. gray, j. e. 1821. on the natural arrangement of vertebrose animals. london medical repository, 15, 296310. heath, m. e. 1995. manis crassicaudata. mammalian species archive, 513, 1-4. heath, m. e. & coulson, i. m. 1997. preliminary studies on relocation of cape pangolins manis temminckii. south african journal of wildlife research-24-month delayed open access, 27, 51-56. hutton, a. 1949. notes on the indian pangolin (manis crassicaudata). j. bombay nat. hist. soc, 48, 805806. irshad, n., mahmood, t., hussain, r. & nadeem, m. s. 2015. distribution, abundance and diet of the indian pangolin (manis crassicaudata). animal biology, 65, 57-71. irshad, n., mahmood, t. & nadeem, m. s. 2016. morpho-anatomical characteristics of indian pangolin (manis crassicaudata) from potohar plateau, pakistan. mammalia, 80, 103-110. israel, s., grewal, b., hoefer, h. & sinclair, t. 1987. indian wildlife: sri lanka, nepal, apa publications, prentice hall. iucn. 2016 red list of threatened species [online]. available: www.iucnredlist.org [accessed 03 may 2017]. jayaratna, c., perera, p.k.p. & dayawansa, n.p. 2015. a preliminary investigation of the behaviour of rusty spotted cats prionailurus rubiginosus in captivity. wildlanka 3 (1): 1-11. kajale, m. 2014. 15 mesolithic exploitation of wild plants in sri lanka: archaeobotanical study at the cave site of beli-lena. foraging and farming: the evolution of plant exploitation, 31, 269. karawita, k., perera, p. & pabasara, m. 2016. indian pangolin (manis crassicaudata) in yagirala forest reserve: ethnozoology and implications for conservation. proceedings of 21st international forestry and environment symposium, 2016, sri lanka. kaspal, p. saving the pangolins: ethno zoology and pangolin conservation awareness in human dominated landscapes of nepal. proceeding of the first one day national seminar on small mammals issues, 2010. 43-58. katuwal, h. b., neupane, k. r., adhikari, d. & thapa, s. 2013. pangolins trade, ethnic importance and its conservation in eastern nepal. small mammals conservation and research foundation and wwf-nepal, kathmandu, nepal. khan, m. a. r. 1985. mammals of bangladesh: a field guide, nazma reza. perera et al. /journal of tropical forestry and environment vol. 07, no. 01 (2017) 1-14 13 kotagama, s. & de a. goonatilake, s. 2013. pictorial pocket guide to the mammals of sri lanka: revised & expanded. lal-mohan, r. 1997. manis crassicaudata of malabar-ecology and status. zoos’ print xii (11): 33, 34. lekagul, b. & mcneely, j. 1977. mammals of thailand. association for the conservation of wildlife. kulusapa, bangkok. lim, n. t. & ng, p. k. 2008. home range, activity cycle and natal den usage of a female sunda pangolin manis javanica (mammalia: pholidota) in singapore. endangered species research, 4, 233-240. mahmood, t., hussain, r., irshad, n., akrim, f. & nadeem, m. s. 2012. illegal mass killing of indian pangolin (manis crassicaudata) in potohar region, pakistan. pakistan j. zool, 44, 1457-1461. mahmood, t., irshad, n. & hussain, r. 2014. habitat preference and population estimates of indian pangolin (manis crassicaudata) in district chakwal of potohar plateau, pakistan. russian journal of ecology, 45, 70-75. mahmood, t., jabeen, k., hussain, i. & kayani, a. r. 2013. plant species association, burrow characteristics and the diet of the indian pangolin, manis crassicaudata, in the potohar plateau, pakistan. pakistan journal of zoology, 45, 1533-1539. marler, p. n. 2016. camera trapping the palawan pangolin manis culionensis (mammalia: pholidota: manidae) in the wild. journal of threatened taxa, 8, 9443-9448. mishra, n. & rout, s. 2009. ethno-zoological studies and medicinal values of similipal biosphere reserve, orissa, india. african journal of pharmacy and pharmacology, 5, 6-11. mishra, s. & panda, s. 2012. distribution of indian pangolin manis crassicaudata gray (pholidota, manidae) in orissa: a rescue prospective. small mammal mail, 3, 51-53. mohapatra, r. k. & panda, s. 2014a. behavioural descriptions of indian pangolins (manis crassicaudata) in captivity. international journal of zoology, 2014. mohapatra, r. k. & panda, s. 2014b. husbandry, behaviour and conservation breeding of indian pangolin. folia zoologica, 63, 73-80. mohapatra, r. k., panda, s., nair, m. v., acharjyo, l. n. & challender, d. w. 2015. a note on the illegal trade and use of pangolin body parts in india. traffic bulletin, 27, 33. newton, p., van thai, n., roberton, s. & bell, d. 2008. pangolins in peril: using local hunters’ knowledge to conserve elusive species in vietnam. endangered species research, 6, 41-53. norman, t. ecological research and conservation of sunda pangolin manis javanica in singapore. workshop on trade and conservation of pangolins native to south and southeast asia, 2009. citeseer, 90. ogilvie, p. & bridgwater, d. 1967. notes on the breeding of an indian pangolin manis crassicaudats at oklahoma zoo. international zoo yearbook, 7, 116-118. pabasara, g. 2016. assessment of the abundance and habitat preference of indian pangolin (manis crassicaudata) in yagirala forest reserve; a tropical lowland forest in south-west sri lanka. pabasara, m., perera, p. & dayawansa, n. 2015. a preliminary investigation of the habitat selection of indian pangolin (manis crassicaudata) in a tropical lowland forest in south-west sri lanka. proceedings of 20th international forestry and environment symposium, 2015, sri lanka. pattnaik, a. 2008. enclosure design and enrichment key to the successful conservation breeding of indian pangolin (manis crassicaudata) in captivity. indian zoo year book v: 91, 102. payne, j. & francis, c. m. 1998 a field guide to the mammals of borneo. the sabah society, kota kinabalu. phillips, w. w. a. 1981. manual of the mammals of sri lanka, wildlife and nature protection society of sri lanka. perera et al. /journal of tropical forestry and environment vol. 07, no. 01 (2017) 1-14 14 prater, s. 1980. the book of indian animals bombay natural history society and oxford university press. mumbai. prater, s. h. 1965. the book of indian animals, bombay natural history society. ramakantha, v. 1992. a note on pangolin in manipur. wii news-letter 7, 19. richer, r., coulson, i. & heath, m. 1997. foraging behaviour and ecology of the cape pangolin (manis temminckii) in north‐western zimbabwe. african journal of ecology, 35, 361-369. roberts, t. 1997. the mammals of pakistan (revised ed.) oxford university press. karachi, pakistan, 525. roberts, t. & vielliard, j. 1971. commentaires sur le grand pangolin indien manis crassicaudata. mammalia, 35, 610-613. rowcliffe, j. m., field, j., turvey, s. t. & carbone, c. 2008. estimating animal density using camera traps without the need for individual recognition. journal of applied ecology, 45, 1228-1236. sanyal, r. b. 1892. a hand-book of the management of animals in captivity in lower bengal, printed at the bengal secretariat press. shek, c.-t., chan, c. s. & wan, y.-f. 2007. camera trap survey of hong kong terrestrial mammals in 2002-06. biodiversity, 15, 1-11. swart, j., richardson, p. & ferguson, j. 1999. ecological factors affecting the feeding behaviour of pangolins (manis temminckii). journal of zoology, 247, 281-292. weber, m. 1904. die" objektivität" sozialwissenschaftlicher und sozialpolitischer erkenntnis. archiv für sozialwissenschaft und sozialpolitik, 19, 22-87. weerakoon, d. k. 2012. the taxonomy and conservation status of mammals in sri lanka. the national red list 2012 of sri lanka,conservation status of the fauna and flora, 138-144. wilson, d. e. & reeder, d. m. 2005. mammal species of the world: a taxonomic and geographic reference, jhu press. wilson, g. j. & delahay, r. j. 2001. a review of methods to estimate the abundance of terrestrial carnivores using field signs and observation. wildlife research, 28, 151-164. wu, s., liu, n., ma, g., xu, z. & chen, h. 2003. habitat selection by chinese pangolin (manis pentadactyla) in winter in dawuling natural reserve. mammalia, 67, 493-502. yadav, r. 1973. rearing of indian pangolin. indian zoo bulletin 1, 6. yang, c. w., chen, s., chang, c. y., lin, m. f., block, e., lorentsen, r., chin, j. s. & dierenfeld, e. s. 2007. history and dietary husbandry of pangolins in captivity. zoo biology, 26, 223-230. zhou, z.-m., zhou, y., newman, c. & macdonald, d. w. 2014. scaling up pangolin protection in china. frontiers in ecology and the environment, 12, 97-98. warrier et al. /journal of tropical forestry and environment vol. 4. no 02 (2014) 45-56 45 storage duration and temperature effects of strychnos potatorum stock solutions on its coagulation efficiency rekha r. warrier * , b. g. singh, c. balaji and p. priyadarshini institute of forest genetics and tree breeding, pob 1061, r.s. puram hpo., coimbatore, india date received: 18-08-2013 date accepted: 31-03-2014 abstract this study presents the effects of storage duration and temperature of strychnos potatorum stock solution on its coagulation efficiency. coagulation efficiency of the seed extracts on water samples depended on the initial turbidity of the water sample. the stock solutions could clarify only highly turbid solutions. the optimum dosage of the stock solutions was 5% and optimal time required was 50 minutes. s. potatorum stock solutions, which were kept at room temperature (28 0 c), had a shelf life of only five days and were able to remove turbidity from high and low turbidity water samples and no coagulation activity was observed for medium turbidity. the highest turbidity removals were observed for stock solutions, which were kept for three days. for stock solutions which were stored in refrigerator, shelf life was extended upto seven days, and the turbidity removal efficiencies improved from 45.9% to 63.8% for low and 43.7% to 64.9 % for high turbidity water samples, respectively. keywords: strychnos potatorum, natural coagulant, storage duration, storage temperature, turbidity removal 1. introduction groundwater is the preferred source for drinking water in rural areas of developing countries and it generally requires no or minimal treatment. in the event that no suitable aquifers are available, relatively clean waters from lakes or streams are preferred. however, only simple, practical technologies such as gravity chemical feed with solutions, hydraulic rapid mixing and flocculation, horizontal-flow sedimentation, and manually operated filters should be used for treatment of such waters (schulz and okun, 1984). the use of natural material of plant origin to clarify turbid surface waters is not a new idea. the use of herbal materials to reduce turbidity, or muddiness in the water and to remove the harmful biological material that can lead to illness is an age-old concept (joshua and vasu, 2013). natural coagulants have been used for domestic household for centuries in traditional water treatment in rural areas. sanskrit writings in india dating from several centuries bc make reference to seeds of the tree strychnos potatorum as a clarifier (bhishagratna, 1991), peruvian texts from the 16 th and 17 th centuries detail the use by sailors of powdered, and roasted grains of zea mays as a means of settling impurities. more recently, chilean folklore texts from the 19 th century refer to water clarification using the sap from the ‘tuna’ cactus scientifically known as opuntia fiscus indica (sutherland et al., 1990). however, of all the plant materials that have been investigated over the years, * correspondence: rekha@icfre.org tel: +91 4222484167 issn 2235-9370 print/issn 2235-9362 online © university of sri jayewardenepura 46 the seeds from m. oleifera have been shown to be one of the most effective as a primary coagulant for water treatment (david, 2004) of turbid water (schulz and okun, 1984). for home water treatment, the materials have to be used in the form of powder or paste, 90% of which consists of substances other than polyelectrolytes. even under such conditions, a few plant seeds make effective coagulants (jahn, 1988), for example, seeds of the plant species of the family loganiaceae (strychnos potatorum), and moringaceae (moringa oleifera and moringa stenopetala). s. potatorum is a small tree occurring abundantly in central and southern india. in laboratory and field studies, seeds of s. potatorum have shown promise as coagulant in the clarification of turbid water (sen and bulusu, 1962; dhekane et al., 1970; tripathi et al., 1976; jahn, 1988; sutherland et al., 1990, 1994; folkard et al., 1995; al-khalili et al., 1997; folkard and sutherland, 2002). studies using the species have focused on quality of water treated by coagulation using the seed. in laboratory tests, direct filtration with s. potatorum seed as coagulant appeared effective in clarifying low turbidity water (abu-ghararah, 1983). rodrigo (2011) conducted a study aimed at investigating the effectiveness of strychnos potatorum seed powder coagulant for the removal of turbidity, water hardness causing cations (mg 2+ , ca 2+ ), heavy metal cations (pb 2+ , cr 3+ , cd 2+ ), fluoride and chemical oxygen demand (cod) of treated water. muthukumaran et al. (2013) used different types of coagulants like moringa oleifera, phaseolus vulgaris and strychnos potatorum for clarifying water. however, storage studies on the seed material have not been attempted. since home treatments demand the use of powder or paste, the goal of the present study was to assess suitability of efficient method for home water treatment in rural areas of developing countries using stock solutions of s. potatorum and its possible shelf life. since, systematic studies on the effects of storage duration and condition on its performance have not yet been carried out, this study aimed to investigate the same. 2. materials and methods 2.1 preparation of stock solutions strychnos potatorum seeds were collected from mettupalaym, coimbatore, india. the seeds were dried in a hot air oven for 24 hours at 50 0 c. the seeds were crushed and ground to a medium fine powder with a domestic food blender (tector). any traces of fat was removed by mixing the powder in 95% ethanol (5-10% w/v) for 30 minutes and the solids separated by centrifugation and dried at room temperature. 5,000 mg of defatted s. potatorum seeds powder was placed in beaker containing 0.1 l of distilled water. the mixture was blended to extract the active ingredient of strychnos potatorum. the suspension was then filtered through a muslin cloth and the filtrate made up to 0.5 l to give a stock solution of 10,000 mg/l. 10,000 mg/l of s. potatorum stock solution was used for test trials that were conducted to determine optimum dosages of s. potatorum on water samples of varying turbidities. turbidity stock solution stock kaolin solution was prepared as 1% (w/v) using distilled water, stirred slowly at 20 rpm for 1 hour for uniform dispersion of kaolin particles. the suspension was then allowed to stand for 24 hours to allow for complete hydration of the kaolin. this kaolin suspension was used as the stock solution for the preparation of water samples of varying turbidities for the coagulation tests. three types of turbidities were carried out namely; i. low turbid: less than 50 ntu ii. medium turbid: in between 50-200 ntu iii. high turbid: more than 200 ntu warrier et al. /journal of tropical forestry and environment vol. 4. no 02 (2014) 45-56 47 storage of seeds stock solution in order to study the effects of storage temperature, the stock solutions were divided into two groups and stored at two different temperatures namely; room temperature (28 0 c) and at 4 0 c (refrigerator). the effects of storage duration on strychnos potatorum stock solution were investigated for 0, 1, 3 and 5 days. 2.2 optimisation of dosage for strychnos potatorum extracts three sets of experiments were carried out with different levels of turbid solutions (low, medium and high). i. optimization of strychnos potatorum dosage with varying concentration (5-25 %) at room temperature and 4 0 c. ii. completely randomized experimental runs with varied time durations (0-150 minutes) and varying storage conditions (room temperature and 4 0 c). iii. completely randomized experiments with varying storage conditions (room temperature and 4 0 c) on different days (0, 1, 3 and 5). the water samples were agitated at the preselected intensity of rapid mixing to obtain samples of varying turbidities. during rapid mixing the crude extract of seeds were added into the samples simultaneously. subsequently the mixture was left for sedimentation to take place. following settling, samples were taken from the middle of each beaker using a pipette and placed in a cuvette for turbidity measurement. for determining the optimum dosage, varying stock concentrations were added into the beakers having different turbidity levels. 2.3 turbidity measurement turbidity measurements were made using a nephelometer (systronics) and expressed in nephelometric turbidity units (ntu) in relation to a control sample in a 1 ml cuvette. 2.4 statistical analysis results, means and standard deviation (s.d.), of the experiments were carried out in all the methods. statistical significance of the differences between mean values was assessed by anova test. 3. results and discussion 3.1 optimization of dosage of strychnos potatorum for turbidity removal results on optimum dosage of s. potatorum to obtain highest turbidity removal on different samples are presented in table 1. turbidity removal efficiency of s. potatorum on low, medium and high level turbid water at 5% was 37.5, 21.8 and 23.8%, respectively. with increasing initial turbidity of the samples, the turbidity removal efficiency reduced. further, for optimum dosage of s. potatorum seeds extract it was observed that increase in dosage reduced the turbidity removal efficiency. this result revealed that the low turbid water sample showed better performance in terms of turbidity removal in the case of s. potatorum. 3.2 effect of storage on optimal dosage of strychnos potatorum for turbidity removal results on the effect of storage on the optimum dosage of s. potatorum to obtain highest turbidity removal on different samples are presented in table 2. results showed that highest turbidity removal was observed with medium turbid samples. it was observed that in the case of strychnos 48 unlike in moringa, the turbidity removal efficiency of the extracts improved with storage. following storage of extract, the turbidity removal efficiency was improved by 26, 63 and 54% for low, medium and high turbidity samples. it was observed that increase in dosage did not improve turbidity removal. however, in the low turbid samples, dosage did not show any significant reduction in efficiency. this suggests that s. potatorum seed extract would be effective for low turbid samples following storage of the extract under cold conditions. turbidity removal efficiency of s. potatorum on low, medium and high level turbid water at 5% was 50.7, 60 and 52.2%, respectively. this result revealed that although the same dosage of moringa oleifera seed extract applied on the three types of water samples, the medium turbid water sample showed better performance in terms of turbidity removal. table 1: optimization of dosage of s. potatorum extracts on different samples. strychnos potatorum extract turbidity measurements (ntu) low medium high control 54.7 174 281 5 % 34.2 136 214* 10 % 36.8 142 229 15 % 39.3 152 244 20 % 43.5 151 256 25 % 48.0 165 271 std. deviation 9.99 6.32 7.91 test value t 5.87 5.04 3.85 sig. (2-tailed) 0.004 0.007 0.018 lower limit 13.83 6.39 3.78 upper limit 38.65 22.09 23.42 * significant variation (p≤0.05) table 2: effect of storage on optimal dosage of s. potatorum extracts on different samples. strychnos potatorum extract turbidity measurements (ntu) low medium high control 56 185 312 5 % 27.6 74 149* 10 % 29.2 80 257 15 % 28.2 86 293 20 % 31.6 98 294 25 % 33.2 113 295 std. deviation 2.80 8.41 20.09 test value t 38.54 13.62 1.94 sig. (2-tailed) 0 0 0.12 lower limit 44.80 40.80 37.51 upper limit 51.76 61.68 42.39 * significant variation (p≤0.05) 3.3 effect of time duration on performance of strychnos potatorum extracts the effect of time period to obtain highest turbidity removal on different samples using s. potatorum is presented in tables 3 and 4 and figure 1. the extended duration was up to 150 minutes. results showed that higher turbidity removal was observed as initial turbidity of water samples was warrier et al. /journal of tropical forestry and environment vol. 4. no 02 (2014) 45-56 49 increased. though initially there was no significant variation in turbidity removal in the low and high turbid samples, following the extended duration, the variations observed was significant suggesting that increase in time period could improve turbidity removal. medium turbid samples could be effectively coagulated in 50 minutes indicating that s. potatorum seed extract would be effective for medium turbid samples in shorter periods of time. with extended durations, turbidity removal efficiency increased for low and high turbid samples. however, it was observed that for medium and high turbid samples, with increasing time period, the residual turbidity was found to increase suggesting that longer durations may not be able to effectively bring in turbidity removal. the time period for significant turbidity removal efficiency of s. potatorum extracts on low, medium and high level turbid water was 90, 50 and 90 minutes, respectively. in this experiment, medium turbid water sample showed quicker turbidity removal. table 3: effect of varying settling time on performance of s. potatorum extracts. time in minutes turbidity measurements (ntu) low medium high 0 48.4 182 252 10 48.1 115 209 20 44.4 102 234 30 46.7 85 193 40 47.8 86 193 50 44.8 82* 192 60 45.1 73* 184 * significant variation (p≤0.05) table 4: effect of extended durations of settling on performance of s. potatorum extracts. time in minutes turbidity measurements (ntu) low medium high 0 59.9 182 238 90 40.7* 145 168* 120 40.6* 140 162* 150 39.6* 149 191 std. deviation 14.30 16.34 7.36 test value t 2.94 7.41 9.18 sig. (2-tailed) 0.02 0.00 0.00 lower limit 3.01 27.79 16.87 upper limit 24.99 52.90 28.19 * significant variation (p≤0.05) 3.4 effect of storage on time duration to assess performance of strychnos potatorum extracts the effect of storage on the time required to obtain highest turbidity removal using strychnos potatorum on different samples are presented in tables 5 and 6 and figure 2. highest turbidity removal was observed with low turbid samples. it was observed that the time duration for turbidity removal reduced with storage. the medium turbid samples showed the fastest removal. this further reiterates the results in table 2 that strychnos potatorum seed extract would be effective for turbid samples following storage of the extract under cold conditions. 50 figure. 1: effect of varying settling time on performance of strychnos potatorum extracts. the low turbid samples could be coagulated in 60 minutes, the medium in 50 minutes and the high at 90 minutes. the results obtained following storage, low turbid samples could be clarified faster while the medium and high turbid samples were on par with the performance of extracts stored at room temperature. however, it was observed that for all the samples, with increasing time period, the residual turbidity was found to increase, suggesting that longer durations may not be able to effectively bring in turbidity removal. in this experiment also, medium turbid water sample showed quicker turbidity removal. table 5: effect of storage on turbidity removal of s. potatorum extracts on different samples at varying time durations. time in minutes turbidity measurements (ntu) low medium high 0 62.1 191 246 10 47.1 105 219 20 42.2 86 202 30 42.2 84 195 40 41.9 84 190 50 39.4 79* 179 60 38.2* 79* 174 * significant variation (p≤0.05) e ffe c t o f v a ry in g s e ttlin g tim e o n p e rfo rm a n c e o f s try c h n o s p o ta to ru m e x tra c ts 0 1 0 2 0 3 0 4 0 5 0 6 0 7 0 1 0 2 0 3 0 4 0 5 0 6 0 9 0 1 2 0 1 5 0 t im e in m in u te s t u rb id it y r e m o v a l % l o w m e d iu m h ig h warrier et al. /journal of tropical forestry and environment vol. 4. no 02 (2014) 45-56 51 table 6: effect of storage on turbidity removal of s. potatorum extracts on different samples at extended time durations. time in minutes turbidity measurements (ntu) low medium high 0 59.9 182 238 90 36.2* 139 147* 120 39 133 165 150 35.8* 131 151* std. deviation 5.04 14.94 8.84 test value t 20.54 9.10 8.84 sig. (2-tailed) 0.00 0.00 0.00 lower limit 30.61 33.82 19.25 upper limit 38.35 56.78 32.84 * significant variation (p≤0.05) figure. 2: effect of storage on turbidity removal of s. potatorum extracts. 3.5 effects of storage duration of strychnos potatorum extracts kept at room temperature (28 0 c) table 7 shows the results of turbidity removal using strychnos potatorum stock solutions, which were kept for 1, 3 and 5 days at room temperature. the results showed that strychnos potatorum kept under this condition were able to remove turbidity from low and high turbidity water samples. however, it was observed that in the medium turbid samples, the residual turbidity was found higher than of the initial turbidity levels. the experiment was not conducted beyond day 5 as the extract began to decay. for the low and high initial turbidity value water samples, the highest turbidity removals were observed for stock solutions which were kept for five days. the turbidity removal efficiencies improved from 31.5 to 52.4 for low and 26.1 to 29.4% for high turbidity water samples, respectively. e ffe c t o f s to ra g e o n tu rb id ity re m o v a l o f s try c h n o s p o ta to ru m e x tra c ts 0 1 0 2 0 3 0 4 0 5 0 6 0 7 0 1 0 2 0 3 0 4 0 5 0 6 0 9 0 1 2 0 1 5 0 t im e in m in u te s t u rb id it y r e m o v a l % l o w m e d iu m h ig h 52 table 7: effects of storage duration of s. potatorum extracts at room temperature. days turbidity measurements (ntu) low medium high day 0 69.9 136 245 day 1 47.9 94 181 day 3 46.7 199 189 day 5 33.3 165 173 std. deviation 11.87 . 3.25 test value t 0.03 . 0.01 sig. (2-tailed) 38.70 . 26.13 lower limit 9.21 . 18.06 upper limit 68.19 . 34.21 * significant variation (p≤0.05) 3.6 effects of storage duration of strychnos potatorum extracts kept under refrigeration (4 0 c) table 8 shows the results of turbidity removal using strychnos potatorum stock solutions, which were kept for 1, 3 and 5 days under refrigerated conditions. the results showed that strychnos potatorum extract kept under this condition was able to remove turbidity from low, medium and high turbidity water samples. however, it was observed that except in the high turbid samples, the medium and low turbid samples did not show a linear increase in turbidity removal. in these cases, the residual turbidity after coagulation on the third day was found higher than the first day, which further reduced on day 5, beyond which the experiment was not conducted. for the low and high initial turbidity water samples, highest turbidity removals were observed for stock solutions which were kept for five days. the turbidity removal efficiencies improved from 45.9 to 63.8 for low and 43.7 to 64.9% for high turbidity water samples, respectively. another interesting observation made through these experiments was that the turbidity removal efficiency of s. potatorum stock solutions increased following storage and with increase in the number of days stored. the maximum was observed in the stock stored for 5 days under refrigerated conditions (64.9%). table 8: effects of storage duration of s. potatorum extracts kept at 4 0 c. days turbidity measurements (ntu) low medium high day 0 69.9 136 245 day 1 37.8 153 138 day 3 39.6 85 88 day 5 25.3 131 86 std. deviation 11.13 23.90 12.02 test value t 7.94 1.22 8.30 sig. (2-tailed) 0.02 0.44 0.01 lower limit 23.39 -194.13 27.72 upper limit 78.67 235.33 87.41 * significant variation (p≤0.05) warrier et al. /journal of tropical forestry and environment vol. 4. no 02 (2014) 45-56 53 figure 3 gives an overall view of the effects of temperature on the turbidity removal efficiency of s. potatorum stock solutions. figure 3: effects of temperature on the storage duration of s. potatorum extracts. a number of effective coagulants have been identified of plant origin. some of the common ones include nirmali (tripathi et al., 1976), m. oleifera (olsen, 1987; jahn, 1988), okra (al-samawi and shokrala, 1996), cactus latifaira and prosopis juliflora, tannin from valonia (özacar and sengil, 2000), apricot, peach kernel and beans (jahn, 2001), and maize (raghuwanshi et al., 2002). bhole (1995) compared 10 natural coagulants from plant seeds. since the early 1970’s a number of studies have been carried out to determine the effectiveness of the seeds for the treatment of surface water (olsen, 1987; jahn 1988; sutherland et al., 1994; muyibi and evison, 1995, 1996; ndabigengesere and narasiah, 1998; ghebremichael et al., 2005) using different extraction methods for the active coagulant from m. oleifera. utilising artificially prepared turbid water and naturally turbid raw waters, laboratory investigations have confirmed the seeds to be highly effective in the removal of suspended solids from waters containing medium to high initial turbidities (sutherland et al., 1994). a comparative study on electro-coagulation and natural coagulation (m. oleifera) methods devised for the treatment of pharmaceutical residues from both, synthetic solutions and real pharmaceutical wastewaters revealed that electro coagulation was a more effective technique than natural process (dixit and parmar, 2013). muthukumaran et al. (2013) reported that sodium chloride extract of moringa was found to provide a high turbidity removal of >99% compared to naoh and distilled water extract of the same species. effective turbidity by strychnos was not effective. however, our studies have proved the efficacy of the water extract of the seeds of s. potatorum in clarying turbid waters to as high as 80%. rodrigo (2011) showed effectiveness of s. potatorum for turbidity removals of up to 92%, 91% and 85% for initial turbidities of 25, 50 and 100 nephlometric turbidity units (ntu) respectively. being a natural coagulant, the species is non-toxic and an effective coagulant aid useful for removing turbidity 0 50 100 150 200 250 300 low turbid medium turbid high turbid low turbid medium turbid high turbid room refrigator temperature n t u day 0 day 1 day 3 day 5 54 from water. muthukumaran et al. (2013) report that the presence of anionic polyelectrolyte, which contains carboxylic (coo ) and hydroxyl (oh ) as main active groups which might play a role in coagulation. 4. conclusions much progress has been made in investigating the coagulation potential of crude seed extracts as well as purified seed proteins from m. oleifera, which have been proven to be the main active agent in seed based coagulants. however, the species s. potatorum, which is popularly used in rural areas for waste water treatments, especially on a large scale has not been studies in depth. hence the present study was taken up to investigate the performance of s. potatorum as a primary coagulant. our studies showed that strychnos extract was effective only for high turbid solutions. it was also observed that storage of extracts at 4 0 c did not improve its turbidity removal efficiency. reduction in turbidity in our experiments is also comparable to those achieved by natural coagulant like m. drouhardii, m. stenopetala and m. peregrine seeds as reported by jahn (1988). these results are also comparable to the result obtained by aririatu et al. (1999), which indicates a reduction in turbidity using moringa seeds in the range of 72.8-92.4% while jatropha curcas was 75.2-84.7%. chemical coagulants, like aluminium sulphate reduced the same turbidity of the same effluent in the range of 66.00-84.29% and ferric chloride in the range of 98.29-99.80%. turbidity removal is very dependent on proper coagulant doses and time but again the fine adjustment is less critical for highly turbid waters, which are thus also easiest to treat in this respect. the chemical composition of the coagulant in s. potatorum has been identified as a polysaccharide consisting of a 1:7 mixture of galactomannan and galactan. these findings suggest that such seed extracts may function as a particulate, colloidal and soluble polymeric coagulant as well as a coagulant aid. the presences of other constituents in these seed extracts are uncertain, because the portions of the plant also are used for medicinal purposes. also, little has been done define, optimize and standardize conditions for their use. thus use of easily available indigenous plants might be seriously considered as a temporary solution where water treatment is badly needed and where the people are very motivated to start as soon as possible. pulses, such as lens esculenta, cajanus indicus and phaseolus roxborghii have been utilized with good success as coagulant aids. the above results confirmed the use of this natural coagulant as a good clarifying agent and also unveil its potential as material for water clarification through coagulation and flocculation process. these studies have indicated that clarification and prepurification (partial purification) of raw water and waste water samples can be obtained using s. potatorum. this method is simple, quick and does not require any special device, regulatory control and technology and would find applicability for home water treatment in rural areas of developing countries. references abu-ghararah, z.h. 1983. polymer application methods in direct filtration. msc thesis. king abdulaziz university, jeddah, india. al-khalili, r.s., sutherland, j.p. and folkard, g.k. 1997. filtration with a natural coagulant. in water and sanitation for all: partnerships and innovations, proceedings of the 23rd wedc conference, 1-5 september 1997. durban, south africa, pp.143–145. al-samawi, a.a. and shokrala, e.m. 1996. an investigation into an indigenous natural coagulant. journal environ. science and health, a31 (8):1881-1897. aririatu, l.e., gwadia, o.t. and nwaokeocha c.c., 1999. the bioremediation potential of some local natural coagulants. nig. journal of microbiology, 13: 65-69. warrier et al. /journal of tropical forestry and environment vol. 4. no 02 (2014) 45-56 55 bhishagratna, k.k. 1991. an english translation of sushruta samhita based on the original sanskrit text. chowkhamba sanskrit series office, varanasi, india. bhole, a.g. 1995. relative evaluation of a few natural coagulants. journal srt-aqua, 44(6):284-290. david odee. 2004. moringa oleifera canadian biotechnical division kenya forestry research institute and moringa medical research institute. http://www.moringa.htm. dhekane, n.y., ambawane, g.b., patil, b.n. and pagar, s.d. 1970. nirmali seed as a coagulant. j. instn engrs india (phe div.), 50(10): 108–112. dixit, d. and parmar, n. 2013. treatment of pharmaceutical waste water by electro-coagulation and natural coagulation process: review. international journal of technical & non-technical research, 4(5): 79-87. folkard, g. and sutherland, j. 2002. development of a naturally derived coagulant for water and wastewater treatment. wat. suppl. 2(5-6): 89-94. folkard, g., sutherland, j. and al-khalili, r. 1995. natural coagulants: a sustainable approach. in: sustainability of water and sanitation systems, proceedings of the 21st wedc conference, 4-8 september 1995, kampala, uganda, pp.263-265. ghebremichael, a.k., gunaratna, k.r., henriksson, h., brumer, h. and dalhammar, g. 2005. a simple purification and activity assay of the coagulant protein from moringa oleifera seed. water res., 39:2338-2344. jahn, s.a.a. 2001. drinking water from chinese rivers: challenges of clarification. journal of water supply res. technol., 50:15-27. jahn, s.a.a. 1988. effectiveness of traditional flocculants as primary coagulants and coagulant aids for the treatment of tropical waters with more than a thousand fold flocculation in turbidity. water supply, 2(3-4): 8-10. joshua, r. and vasu, v. 2013. characteristics of stored rain water and its treatment technology using moringa seeds. international journal of life sc. bt & pharm. res., 2(1): 155-174. muthuraman, g., sasikala, s. and prakash, n. 2013. proteins from natural coagulant for potential application of turbidity removal in water. international journal of engineering and innovative technology, 3(1): 278-283. muyibi, s.a. and evison, l.m. 1995. optimizing physical parameters affecting coagulation of turbid water with moringa oleifera seeds. water resources, 29(12): 2689-2695. muyibi, s.a. and evison, l.m. 1996. coagulation of turbid water and softening of hard water with moringa oleifera seeds. international journal of environmental studies, 56: 483-495. ndbigengesere, a. and narasiah, k.s. 1998. quality of water treated by coagulation using moringa oleifera seeds. water resources, 32(3):781-791. olsen, a. 1987. low technology water purification by bentonite clay and moringa oleifera seed flocculation as performed in sudanese village: effects on schistosoma mansoni cercariae. water resources, 21(5): 517-522. özacar, m. and sengil, i.a. 2000. effectiveness of tannins obtained from valonia as a coagulant aid for dewatering of sludge. water resources, 34(4):1407-1412 raghuwanshi, p.k., mandloi, m., sharma, a.j., malviya, h.s. and chaudhari, s. 2002. improving filtrate quality using agrobased materials as coagulant aid. water quality research journal of canada, 37(4): 745-756. rodrigo, p.d.t. 2011. investigation on the natural water coagulant, strychnos potatorum ("ingini") seed powder for drinking water treatment. a project report submitted to university of peradeniya, sri lanka. pp.1-4. schulz, c.r. and okun, d.a. 1984. surface water treatment for communities in developing countries. john wiley & sons, new york. 56 sen, a.k. and bulusu, k.r. 1962. effectiveness of nirmali seed as coagulant and coagulant aid. environment health, 4(3): 233-244. sutherland, j.p., folkard, g.k. and grant, w.d. 1990. natural coagulants for appropriate water treatment: a novel approach. waterlines, 8(4): 30-32. sutherland, j.p., folkard, g.k., matawali, m.a. and grant, w.d. 1994. moringa oleifera as a natural coagulant. in: affordable water supply and sanitation, proceedings of the 20th wedc conference, 22–26 august 1994, colombo, sri lanka, pp.297-299. tripathi, p.n., chaudhuri, m. and bokil, s.d. 1976. nirmali seed: a naturally occurring coagulant. indian journal of environment health, 18(4): 272–281. ratnayake/ journal of tropical forestry and environment vol. 10 no. 01 (2020) 1-16 feature article _____________________________________________ *correspondence: as_ratnayake@uwu.ac.lk tel: +94 719445860 © university of sri jayewardenepura 1 characteristics of lowland tropical peatlands: formation, classification, and decomposition a.s. ratnayake* department of applied earth sciences, faculty of applied sciences, uva wellassa university, badulla, sri lanka abstract tropical peatlands occur mostly in coastal lowlands, and it can be considered as larger sinkers of carbon and important ecosystem services for water resources, bio-resources and biodiversity. this article summarised characteristics, formation and classification of tropical lowland peatlands. tropical peatlands cover about 11% of the global peatland resource (441,025 km 2 in area) and the estimation value can be changed with including all histosols and shallow organic soils. tropical coastal peatlands were predominantly developed during the middle to late holocene (between 3,500 to 6,000 years bp) under the wet conditions generated after the stabilisation and regression of middle holocene sea-level highstands. hydrology is a fundamental factor to the formation and function of tropical peatlands. there is no specific definition for the peatlands based on available references. the available definitions can be broadly divided into authoritative and scientific definitions. the authoritative definitions depend on specific uses and applications, while scientific definitions depend on field observations and experimental design/analytical methods. tropical peatlands store abundant organic matter. however, the recent anthropogenic activities enhance the emission of stored carbon as greenhouse gasses such as ch4 and co2. keywords: mire, carbon accumulation, groundwater level, peatland disturbance, greenhouse gas emissions 1. introduction peatlands are a unique terrestrial ecosystem that can act as an efficient terrestrial carbon sinker. for example, it is estimated that the total peat carbon burial is around 600 gt c (yu, 2011; charman et al., 2013). peatlands consist of partially decomposed former terrestrial vegetation in various stages of humification under usually waterlogged and acidic conditions. peatlands contain about 30% of the global soil carbon and 10% of the global freshwater aquifers (tarnocai and stolbovoy, 2006). these wetland ecosystems are characterised by a net accumulation of organic matter, as the rate of biomass production exceeds the rate of decomposition (chimner and ewel, 2005; moore et al., 2013; draper et al., 2014). peatlands spread about 3% (i.e., about 5 million km 2 ) of the global land area (figure 1a). the prominent northern hemisphere peatlands (about 89% of total peatlands area) cover russia, north america, and europe (immirzi et al., 1992; rydin and jeglum, 2013; xu et al., 2018). the second larger tropical peatlands cover southeast asia, south america, and africa. tropical peatlands (about 11% of total peatlands area) contain around 50 to 70 gt c. in addition, tropical peatlands contribute 16-21% of global peat soil carbon pool (gorham, 1991; immirzi et al., 1992; page et al., 2002). doi: https://doi.org/10.31357/jtfe.v10i1.4685 2 figure 1. (a) global peatland distribution where peatland area was estimated based on histosols (source: xu et al., 2008) and (b) pie charts showing peatland areas in different geographical regions of the world (km 2 ) based on raw data of (i) lappalainen (1996) (best estimation, consider the provenance of data and assess the parameters) and (ii) joosten and clarke (2002) (maximum estimation considering histosols and shallow organic soils). tropical peatlands can be further categorised as low altitude coastal peatlands (less than normally 30 m from mean sea-level) and mountain peatlands (altitude at least higher than 2,300 m) (bosman et al., 1994; page et al., 2006; chimner and karberg, 2008; hribljan et al., 2016). the lowland tropical peatlands support a growing of swamp forests such as mangroves. however, mountain peatlands are considerably smaller than lowland coastal peatlands, and occurring mainly in basins and slopes of mountains. tropical coastal peatlands are gradually exploited for several of human uses. therefore, the rates of disturbance and destruction are currently high. understanding of carbon cycle in tropical peatlands would help decision-makers for arranging protection and sustainable management activities. consequently, this feature article outlines the distribution of tropical peatlands, genesis/formation processes, definition and classification, and recent anthropogenic disturbance of tropical peatlands based on published papers and documents. ratnayake/ journal of tropical forestry and environment vol. 10 no. 01 (2020) 1-16 3 2. tropical peatlands in tropic, peat is mainly formed under high precipitation and high-temperature conditions, and it is characterised by remains of branches, leaves, roots, and trunks of rainforest trees (table 1). the largest area of tropical peatlands covers coastal lowlands, while tropical peatlands also found at higher altitudes. several evaluations have been made to estimate the global and tropical areas and carbon accumulations of peatlands i.e., armentano and menges (1986), gorham (1991), immirzi et al. (1992), joosten and clarke (2002), jaenicke et al. (2008), donato et al. (2011), page et al. (2011), yu (2011), kurnianto et al. (2015), gallego-sala et al. (2018), xu et al. (2018). however, all these estimations have limitations and uncertainties due to (i) a lack of detailed information in a different geographical region (e.g. central and south america, africa, and south asia), (ii) different definitions of peat, (iii) different survey methods, and (iv) the difficulty to carry out ground surveys in remote areas. for example, lappalainen (1996) estimated that the peatland areas in north america, asia, and europe are 1,735,000 km 2 , 1,119,000 km 2 , and 957,000 km 2 , respectively (figure 1b). however, joosten and clarke (2002) estimated that the peatland areas in north america, asia, and europe are 1,860,000 km 2 , 1,523,287 km 2 , and 617,492 km 2 , respectively (figure 1b). table 1: characteristics of common peat materials. peat type dominant plant material sphagnum sphagnum mosses (sphagnum spp.) sedge sedges (carex spp.) brown moss sedge brown mosses (drepanocladus spp., calliergon spp., aulacomium spp.) and sedges woody sedge sedges and wood (derived from coniferous and deciduous tree species) woody wood feather moss feather mosses (hypnum spp., hylocomium spp., and pleurozium spp. sedimentary aquatic plants (algae, diatoms, aquatic mosses, and other aquatic organisms) amorphous not recognisable (plant materials that are unspecified by the naked eye) page et al. (2011) carried out the best estimation on tropical peatlands between 23.5 o n and 23.5 o s considering the area, thickness and volume and carbon content of peat (figure 2). the world‟s largest peatland locates in southeast asia, and the second and third larger peatlands locate in south america and africa, respectively (figure 2). according to page et al. (2011), peat is defined as “the surface layer of soil, consisting mostly of partially decomposed vegetation, with at least 65% organic matter content in a minimum thickness of 30 cm”. besides, this estimation was done to assess the input of tropical peatlands to nation (by country), geographical/regional and global levels (figure 2). tropical peatlands provide valuable ecological functions and environmental services such as biodiversity, water cycling, and commodities for exploitation (maltby and immirzi, 1993; chimner and ewel, 2005; page et al., 2009; donato et al., 2011; alongi, 2012; dubois et al., 2018). tropical coastal peatlands support plant and animal species, develop buffer zone between saltwater and freshwater hydrological systems in coastal areas, and provide the socio-economic benefits (e.g. agriculture, food, shelter, medicine, etc.) for local communities. besides, the vegetation of tropical coastal peatlands is characterised by unique adaptations such as viviparous embryos, aerial roots to tolerate salt, anoxic and waterlogged soils (jaenicke et al., 2008; alongi, 2012; kurnianto et al., 2015). therefore, these plants are limited at geographical scale. for example, the review of posa et al. (2011) reported that 172 plant species (about 11%) are only restricted to peat swamp forests out of recorded 1,524 plant species in peat swamp forests of southeast asia. 4 figure 2. pie chart showing tropical peatland areas in different geographical regions of the world (km 2 ) based on raw data of page et al. (2011). ratnayake/ journal of tropical forestry and environment vol. 10 no. 01 (2020) 1-16 5 figure 3. general trend of different types of coal production from peat swamp (mire). tropical peatlands contain about 2-3% of the total soil carbon pool in the world (gorham, 1991; immirzi et al., 1992; page et al., 2002, 2007). consequently, tropical peatlands are important research areas for biogeochemistry and paleoenvironmental information. for example, paleo tropical peat deposits during the carboniferous, jurassic, cretaceous and miocene periods can be identified as the precursors of coal deposits (esterle and ferm, 1994; phillips and bustin, 1996, 1998; wüst et al., 2003; ratnayake and sampei, 2015). peat accumulation had expanded several tens of thousands of years under warm and humid climatic conditions and with a constant subsidence rate (figure 3). it is estimated that about 3 m thick coal seams could be equivalent to about 25 m thick peat layer (large et al., 2004). however, the modern tropical peatlands have rarely 6-8 m thick layer since most of the present tropical peat deposits formed after the last glacial maximum. 3. tropical peat formation peat has mainly composed the remains of plant materials that deposit by the vegetation growing under different morphological conditions (table 2). the near-surface peat layer is known as the acrotelm layer (oxic peat layer). this rooting zone is characterised by adding and decomposition of organic matter. however, plant nutrient elements are low in the acrotelm layer that can be influenced by plants growing. the underline anoxic layer (catotelm) is normally submerged below the water table and organic matter decomposition is low. table 2: characteristics of peat classes. peatland class description bogs having water table at or near the surface. the bog surface raise or level with the surrounding terrain. the dominant peat materials are weakly to moderately decomposed and acidic. e.g. moss and woody peat. fens having water table at or just below the surface. the dominant peat materials are moderately to well decomposed and slightly acidic to neutral. e.g. sedge and/or brown moss peat. swamps having water gently flowing through pools/channels. the dominant peat materials are well decomposed and strongly to slightly acidic. e.g. woody peat. marshes periodically inundated by slowlymoving, nutrient-rich water. surface water levels fluctuate seasonally. the dominant peat materials are well-decomposed and slightly acidic to neutral. e.g. reeds and aquatic vegetation. organic matter decomposition is high (about 80%) in the uppermost acrotelm layer. after that, about 10% of organic matter can be lost in the lowermost catotelm (kuhry and vitt, 1996; turetsky et al., 2014). carbon budget of peatlands is mainly controlled by microbial oxidation of organic fraction, and it is represented in equation 1. this reaction is mainly controlled by oxygen level, temperature and water saturation in soil. therefore, organic matter preservation in peatlands can also relate to meteorological records. geological conditions also play a key role in peat formation. peatlands are generally formed on impermeable substrates such as clay that delay the drainage of surface water. the term mire is used to describe currently forming and accumulating active peatlands. in tropics, peat forms normally under the hot and humid conditions that enhance production rates and decomposition rates, especially in leaves. aboveground plant production can be identified as the (1) 6 primary source of peat (table 1). roots of plants also play an important role to accumulate peats in tropics due to its slower decomposition rates (thormann et al., 2001; chimner and ewel, 2005). tropical peat formation can be mainly explained using two major possible mechanisms considering microbial decomposition. firstly, water-saturated humid conditions reduce microbial decomposition and preservation of terrestrial organic matter due to the reduction of oxygen deficiency (chimner and ewel, 2005; page et al., 2006; hirano et al., 2009). the constant water-saturated environment can be observed in the humid tropics since precipitation is higher than evaporation throughout the year. the high rainfall and waterlogged soils provide favorable conditions for peat accumulation and carbon storage. therefore, peat decomposition and co2 release would enhance due to a drop in groundwater table (i.e., increase oxic peat layer/the acrotelm) with decreasing either quantity or frequency of rainfall. the water budget of peatlands is represented in equation 2. ( ) where: p=precipitation g=groundwater inflow m=soil water storage r=surface storage q=runoff e=evapotranspiration secondly, unfavorable chemical conditions in soils such as high levels of sulfur especially in mangrove clay, acidity and high levels of fulvic acids and polyphenols in plant litters also reduce microbial decomposition and preservation of terrestrial organic matter (bruenig, 1990; hirano et al., 2009). consequently, these two major processes promote the higher rate of terrestrial organic matter preservation than the decomposition. tropical peat deposits have been recorded in coastal plains and inland high altitude areas. coastal peatlands are common in tropics that develop over marine sediments of clay and silt and 1-2 m above sea-level. this type of peatlands associated with mangrove swamps and brackish water bodies. the abundance of sulfides in brackish mangrove muds limits bacterial activities and it is the best explanation for the tropical mangrove peat formation. according to page et al. (2004) and rieley et al. (2008), tropical coastal peatlands have extensively developed during the middle holocene. besides, the formation of tropical coastal peatlands began under not only the wet climatic conditions and but also fluctuations in middle holocene sea-level and coastal geomorphological changes. paleoenvironmental studies suggested that lowland tropical coastal peatlands in asia (mainland) commenced around 4,0005,000 cal yr bp followed by the stability of rising sea-levels (anderson and muller, 1975; jaenicke et al., 2008; dommain et al., 2011; donato et al., 2011). therefore, lowland tropical coastal peatlands is a primary feature of the holocene. however, the initiation dates of most of the sub-coastal and inland peatlands commenced from the late pleistocene (ca. 29,000 cal yr bp) to early holocene (9,000 cal yr bp) (staub and esterle, 1994; page et al., 2004; jaenicke et al., 2008; dommain et al., 2011; kurnianto et al., 2015). the water availability/groundwater level plays a key role in formation and storage carbon and preserving biodiversity in peatlands (hirano et al., 2009; page et al., 2009; yu et al., 2010; charman et al., 2013; turetsky et al., 2014). deforestation, ecosystem change (farming) and drainage reduce the water content in peatlands (figure 4). fire, runoff of black carbon, microbial degradation also decreases a large amount of carbon contents in peatlands (figure 4). furthermore, microbial decomposition can enhance under the drop of groundwater level. the water table can be changed by decreasing tree growth (2) ratnayake/ journal of tropical forestry and environment vol. 10 no. 01 (2020) 1-16 7 and increasing tree mortality. consequently, carbon balance in peatlands can be estimated by flux or loss of carbon followed by the groundwater level in peat. figure 4. the effects of water to control carbon content as flux or loss from peatlands. 4. definition and classification several scientific definitions have been used to define peat and peatland based on countries and disciplines (maltby and immirzi, 1993; yu et al., 2010; page et al., 2011; xu et al., 2018). although the definition of peatland is most essential topics for policy design and implication, the intergovernmental panel on climate change (ipcc) also uses classification methods rather than a specific definition. according to the ramsar convention, “peatland are ecosystems with a peat deposit that may currently support vegetation that is peat-forming, may not, or may lack vegetation entirely. peat is dead and partially decomposed plant remains that have accumulated in situ under waterlogged conditions”. the available peatlands definitions can be broadly classified as authoritative and scientific. in general, the authoritative definitions depend on objectives (specific uses and applications), visions and missions of the organization. for example, three different authorities in indonesia define peat in different ways. according to the ministry of environment, “peat is a plant residue formed naturally through long-term decomposition processes, accumulating in swamp areas or static reservoirs”. according to the ministry of agriculture, “peat is a soil formed as a result of organic matter accumulation with a naturally occurring composition of greater than 65% from the decaying vegetation growing on it, whose decomposition is slowed down by anaerobic and wet conditions”. however, according to the ministry of forestry, “peat is an organic matter residue accumulating over a long period of time”. consequently, the differences in definition and data uncertainties can make significant gaps to reach national policy design and implication, and monitoring system. scientific definitions mainly depend on field observations and experimental designs such as types of data, methods, assumptions, analytical techniques and physical properties i.e., kuhry and vitt (1996), wüst et al. (2003), ballhorn et al. (2009), yu et al. (2010), page et al. (2011), donato et al. (2011), draper et al. (2014), kurnianto et al. (2015), gallego-sala et al. (2018). for example, different physical properties (e.g. degree of decomposition/humification, bulk density, water content, porosity) 8 and chemical properties (e.g. ash content, carbon content, ph, and c/n ratio) have been applied to define and classify peat/peatlands in the literature. similarly, several peatland classifications have been used based on the shape/height of the peatlands, vegetation cover, water chemistry/hydrology, soils, etc. figure 5. classification diagram of tropical peatlands based on ash and carbon contents (modified after wüst et al., 2003). wüst et al. (2003) proposed one of the best classifications for lowland tropical peatlands and organic soils based on ash and carbon contents (figure 5). tropical peatlands can be classified into several groups such as very low ash (0-5%), low ash (5-15%), medium ash (15-25%), high ash (2540%), and very high ash (40-55%) peats (figure 5). besides, ash content (≥35%), peat depth (≥50 cm) and carbon content (≥12%) can be identified as key elements to define peatlands. the total organic carbon content of tropical peat is normally higher than 50% (wt.) and total nitrogen content is about 2% (wt.) (kurnain et al., 2001; wüst et al., 2003). however, c/n ratio can be varied in peatlands, and it increases normally with increasing depth due to preferential decomposition of organic matter (kuhry and vitt, 1996; ratnayake et al., 2017). in contrast, it is difficult to distinguish muck and organic-rich mud in the field, as it is quite a gradual transition from peat to mineral soil. several physical and chemical properties such as wood content, microbial activity, degree of decomposition, stratification, compaction, and land-use practices have been controlled the nature of peatlands (kurnain et al., 2001; wüst et al., 2003; yu et al., 2010; turetsky et al., 2014; dargie et al., 2017). several analytical techniques also use to investigate the geochemistry of peatlands for different objectives. for example, biomarkers are molecules compounds derived from biological sources that can retain certain information such as origin, past depositional environment and climate in geological formations. biomarker studies of non-emergent vascular plants consist of c21, c23 and c25 n-alkanes, whereas vascular terrestrial plants consist of c27, c29 and c31 n-alkanes (meyers and ishiwatari, 1993; beilman et al., 2020; freimuth et al., 2020). ratnayake et al. (2019) examined the biomarker distribution of n-alkanes in several terrestrial ecosystems (figure 6). a ternary n-c27-n-c29-n-c31 diagram shows that peatlands are enriched in n-c31 due to the occurrence of grasses, floating plants herbaceous vegetation in swamps. therefore, biomarkers provide unique information to distinguish peatlands, paleo-ecological ratnayake/ journal of tropical forestry and environment vol. 10 no. 01 (2020) 1-16 9 changes and paleo-environments. specific biomarkers such as terpenoids and multivariate analysis of a large set of organic compounds can also be applied for detailed information on vegetation changes, decomposition trends and climatic changes. figure 6. ternary n-c27, n-c29 and n-c31 n-alkanes diagram shows a comparison of mid-latitude and high-latitude peat bogs (i.e., eroded peat from the german wadden sea, birch-alder-oak woodland peat, reed peat, heather-sphagnum peat, transition bog, unspecified fen bog peat, woodland peat, raised bog peat, heather-sphagnum-woolgrass peat), vegetation changes from birch forest to grass and herbs in central europe, temperate woody gymnosperm and angiosperm and tropical brackish lake sediments data from the literature (volkman et al., 2000; schwark et al., 2002; bush and mcinerney, 2013; ratnayake et al., 2019). 5. greenhouse gasses emission from peatlands tropical peatlands can be identified as a hot spot for carbon and nitrogen burial (canadell et al., 2007; ratnayake et al., 2018; beilman et al., 2020). in recent decades, tropical peatlands are under stress due to human-induced destructions. for example, land-use change/land degradation leads to release of stored carbon in the form of greenhouse gases that contribute to climate change (ballhorn et al., 2009; dommain et al., 2011; alongi, 2012; turetsky et al., 2014; hribljan et al., 2016). besides, carbon emissions from land-use change are the most uncertain component of the global carbon cycle. for example, harris et al. (2012) estimated carbon emissions (tg c year -1 ) in the tropical region due to loss of gross forest cover between 2000 and 2005. according to figure 7, latin america and caribean produced the highest carbon emission (384 tg c year -1 ) between 2000 and 2005 and accounted for nearly 59% of total emissions from tropical deforestation. south and southeast asia produced 209 tg c year -1 between 2000 and 2005 and accounted for nearly 32% of total emissions from tropical deforestation (figure 7). furthermore, gross forest cover loss (mha year -1 ) shows a positive correlation with carbon emissions (tg c year -1 ) in selected tropical forest areas (figure 8). similarly, anthropogenic activities and climatic changes (e.g. temperature) can become major drivers for the emission of co2, 10 ch4 and n2o from tropical peatlands (jauhiainen et al., 2005; hirano et al., 2009; hooijer et al., 2010; moore et al., 2013; sjögersten et al., 2014). figure 7. carbon emissions (tg c year -1 ) in different tropical geographical regions due to gross forest cover loss between 2000 and 2005. raw data obtained from harris et al. (2012). figure 8. relationship between carbon emissions (tg c year -1 ) and gross forest cover loss (mha year -1 ) in selected tropical forests. (data points indicate colombia, bolivia, argentina, ratnayake/ journal of tropical forestry and environment vol. 10 no. 01 (2020) 1-16 11 venezuela, the democratic republic of the congo, mozambique, tanzania, zambia, cameroon, indonesia, malaysia, myanmar, india and thailand. raw data were obtained from hansen et al. (2010) and harris et al. (2012). figure 9. schematic diagram shows “co2 emissions from drainage-related peat decomposition”. in tropical peatlands, co2 emission is more prominent than ch4 emission. however, it is estimated that undisturbed tropical wetlands also produce about 85 to 184 tg of ch4 each year (sjögersten et al., 2014 and references therein). besides, the emission of ch4 in tropical peatlands is normally low about 20% compared to temperate and boreal peatlands due to an abundance of hardly decomposable organic compounds such as lignin (jauhiainen et al., 2005; couwenberg et al., 2010). the net greenhouse gasses emission of peatlands is controlled by several components such as (i) net co2 absorbed by vegetation, (ii) co2 emission due to drainage-related peat decomposition and peat fires, (iii) exports of dissolved and particulate organic carbon, and (iv) minor emissions of ch4 and possibly n2o. however, “co2 emissions from drainage-related peat decomposition” can be identified as the dominant component for the greenhouse gasses emission from the peatlands. the drop of the groundwater table promotes aerobic microbial activity and enhances co2 release by peat decomposition (figure 9). similarly, moore et al. (2013) discussed nature of the fluvial carbon losses under the drainage and deforestation on tropical peatland. 6. sustainable management of peatlands in sri lanka peatlands in sri lanka are located mostly along the south to west coasts as isolated patches. muthurajawerla swamp is the largest coastal peat deposit in sri lanka that covers about 21 km 2 . the average thickness of this peat deposit is about 3.7 m, and the maximum thickness is about 5.0 m. the ph values of muthurajawerla swamp range from 3 to 5 (dissanayake et al., 1982). the color of peat varies from grey to black. the texture of peat varies from spongy to fibrous. organic geochemical studies 12 suggested that total organic carbon and total nitrogen contents increase up to 58.0% and 1.4%, respectively (dissanayake et al., 1982). the water level is about 15-30 cm high above the surface during wet season, and the water level drops to surface level during the dry season. three types of peat can be recognised in muthurajawerla swamps, namely (i) shrub and tree group (contain mainly the remains of trunks, roots and shrubs), (ii) reed and sedge group (contain mainly reeds, sedges, and other grasses vegetation in the swamp), (iii) human group (contain mainly decomposed peat and difficult to identify original vegetation). high altitude peatlands are also located in nuwara eliya mountains (e.g. horton plains) in sri lanka with an altitude greater than 2,200 m. previous investigations suggested that initial peat accumulation began ca. 17,100 cal year bp in the deeper part of valley bottoms in the horton plains. peat formation enhanced after 7,800 cal year bp, corresponding to climatic changes (premathilake and risberg, 2003). pollen analysis further suggested that gaultheria leschenaultii, psychotria zeylanica, rubus leucocarpus, and symplocos bractealis have been associated with peat accumulation in the horton plains (premathilake et al., 1999). on the other hand, it is important to take necessary actions for peatland/wetland management in sri lanka to conserve and mitigate the existent of damages. figure 10. sustainable management model for peatland in sri lanka. most of the governments in developed countries have been identified the utilisation of peatlands sustainably. however, practices of sustainable management are largely lacking due to inadequate assessment in most of the developing countries in the tropics. consequently, it is important to manage tropical peatlands sustainably for conserving resources and generating maximum benefits for current and future generations. the proposed model (figure 10) can be implemented for strategic sustainable ratnayake/ journal of tropical forestry and environment vol. 10 no. 01 (2020) 1-16 13 management in tropical coastal peatlands in sri lanka. this strategy involves evaluation of function and uses (ecology, hydrology, biodiversity, and carbon storage), understanding of stakeholders and challenges facing during the management and implementation of socio-economic, cultural and ecological management plans for mitigation past, present and future damages. acknowledgement this research was supported by the accelerating higher education expansion and development (ahead) operation of the ministry of higher education funded by the world bank. i would like to further acknowledge jiren xu, university of leeds, uk for providing copyright permission of the peatmap. k.h.m. sudesh is thanked for the assistance made to compile figures. references alongi, d.m., 2012. carbon sequestration in mangrove forests. carbon management, 3:313-322. anderson, j.a.r. and muller, j., 1975. palynological study of a holocene peat and a miocene coal deposit from nw borneo. review of palaeobotany and palynology, 19:291-351. armentano, t.v. and menges, e.s., 1986. patterns of change in the carbon balance of organic soilwetlands of the temperate zone. the journal of ecology, 74:755-774. ballhorn, u., siegert, f., mason, m. and limin, s., 2009. derivation of burn scar depths and estimation of carbon emissions with lidar in indonesian peatlands. proceedings of the national academy of sciences, 106:21213-21218. beilman, d.w., massa, c., nichols, j.e., timm, o.e., kallstrom, r. and dunbar-co, s., 2020. dynamic holocene vegetation and north pacific hydroclimate recorded in a mountain peatland, moloka„i, hawai„i. frontiers in earth science, 7:188. bosman, a.f., hooghiemstra, h. and cleef, a.m., 1994. holocene mire development and climatic change from a high andean plantago rigida cushion mire. the holocene, 4:233-243. bruenig, e.f., 1990. oligotrophic forested wetlands in borneo. ecosystems of the world, 15:299-334. bush, r.t. and mcinerney, f.a., 2013. leaf wax n-alkane distributions in and across modern plants: implications for paleoecology and chemotaxonomy. geochimica et cosmochimica acta, 117:161-179. canadell, j.g., pataki, d.e., gifford, r., houghton, r.a., luo, y., raupach, m.r. and steffen, w., 2007. saturation of the terrestrial carbon sink. in: terrestrial ecosystems in a changing world, springer, berlin, heidelberg, pp. 59-78. charman, d.j., beilman, d.w., jackson, s.t., korhola, a., mauquoy, d., mitchell, f.j. and alm, j., 2013. climate-related changes in peatland carbon accumulation during the last millennium. biogeosciences, 10:929-944. chimner, r.a. and ewel, k.c., 2005. a tropical freshwater wetland: ii. production, decomposition, and peat formation. wetlands ecology and management, 13:671-684. chimner, r.a. and karberg, j.m., 2008. long-term carbon accumulation in two tropical mountain peatlands, andes mountains, ecuador. mires and peat, 3:1-10. couwenberg, j., dommain, r. and joosten, h., 2010. greenhouse gas fluxes from tropical peatlands in south‐east asia. global change biology, 16:1715-1732. dargie, g.c., lewis, s.l., lawson, i.t., mitchard, e.t., page, s.e., bocko, y.e. and ifo, s.a., 2017. age, extent and carbon storage of the central congo basin peatland complex. nature, 542:86-90. dissanayake, c.b., senaratne, a. and gunatilaka, a.l., 1982. organic geochemical studies of the muthurajawela peat deposit of sri lanka. organic geochemistry, 4:19-26. 14 dommain, r., couwenberg, j. and joosten, h., 2011. development and carbon sequestration of tropical peat domes in south-east asia: links to post-glacial sea-level changes and holocene climate variability. quaternary science reviews, 30:999-1010. donato, d.c., kauffman, j.b., murdiyarso, d., kurnianto, s., stidham, m. and kanninen, m., 2011. mangroves among the most carbon-rich forests in the tropics. nature geoscience, 4:293-297. draper, f.c., roucoux, k.h., lawson, i.t., mitchard, e.t., coronado, e.n.h., lähteenoja, o. and baker, t.r. 2014. the distribution and amount of carbon in the largest peatland complex in amazonia. environmental research letters, 9:124017. dubois, n., saulnier-talbot, é., mills, k., gell, p., battarbee, r., bennion, h. and gomes, d.f., 2018. first human impacts and responses of aquatic systems: a review of palaeolimnological records from around the world. the anthropocene review, 5:28-68. esterle, j.s. and ferm, j.c., 1994. spatial variability in modern tropical peat deposits from sarawak, malaysia and sumatra, indonesia: analogues for coal. international journal of coal geology, 26:1-41. freimuth, e.j., diefendorf, a.f., lowell, t.v., bates, b.r., schartman, a., bird, b.w. and stewart, a. k., 2020. contrasting sensitivity of lake sediment n-alkanoic acids and n-alkanes to basin-scale vegetation and regional-scale precipitation δ 2 h in the adirondack mountains, ny (usa). geochimica et cosmochimica acta, 268:22-41. gallego-sala, a.v., charman, d.j., brewer, s., page, s.e., prentice, i.c., friedlingstein, p. and blyakharchuk, t., 2018. latitudinal limits to the predicted increase of the peatland carbon sink with warming. nature climate change, 8:907-913. gorham, e., 1991. northern peatlands: role in the carbon cycle and probable responses to climatic warming. ecological applications, 1:182-195. hansen, m.c., stehman, s.v., potapov, p.v., loveland, t.r., townshend, j.r., defries, r.s. and carroll, m., 2008. humid tropical forest clearing from 2000 to 2005 quantified by using multitemporal and multiresolution remotely sensed data. proceedings of the national academy of sciences, 105:9439-9444. harris, n.l., brown, s., hagen, s.c., saatchi, s.s., petrova, s., salas, w. and lotsch, a., 2012. baseline map of carbon emissions from deforestation in tropical regions. science, 336:1573-1576. hirano, t., jauhiainen, j., inoue, t. and takahashi, h., 2009. controls on the carbon balance of tropical peatlands. ecosystems, 12:873-887. hooijer, a., page, s., canadell, j.g., silvius, m., kwadijk, j., wösten, h. and jauhiainen, j., 2009. current and future co2 emissions from drained peatlands in southeast asia. biogeosciences, 7:1505-1514. hribljan, j.a., suárez, e., heckman, k.a., lilleskov, e.a. and chimner, r.a., 2016. peatland carbon stocks and accumulation rates in the ecuadorian páramo. wetlands ecology and management, 24:113-127. immirzi, c.p., maltby, e. and clymo, r.s., 1992. the global status of peatlands and their role in carbon cyclking. london:friends of the earth, pp. 1-145 jaenicke, j., rieley, j.o., mott, c., kimman, p. and siegert, f., 2008. determination of the amount of carbon stored in indonesian peatlands. geoderma, 147:151-158. jauhiainen, j., takahashi, h., heikkinen, j.e., martikainen, p. j. and vasander, h., 2005. carbon fluxes from a tropical peat swamp forest floor. global change biology, 11:1788-1797. joosten, h. and clarke, d., 2002. wise use of mires and peatlands. international mire conservation group and international peat society, 304. kuhry, p. and vitt, d.h., 1996. fossil carbon/nitrogen ratios as a measure of peat decomposition. ecology, 77:271-275. ratnayake/ journal of tropical forestry and environment vol. 10 no. 01 (2020) 1-16 15 kurnain, a., notohadikusumo, t., radjagukguk, b. and hastuti, s., 2001. peat soil properties related to degree of decomposition under different land use systems. international peat journal, 11:67-77. kurnianto, s., warren, m., talbot, j., kauffman, b., murdiyarso, d. and frolking, s., 2015. carbon accumulation of tropical peatlands over millennia: a modeling approach. global change biology, 21:431-444. lappalainen, e., 1996. global peat resources. finland: international peat society, vol. 4, p. 358. large, d.j., jones, t.f., briggs, j., macquaker, j.h. and spiro, b.f., 2004. orbital tuning and correlation of 1.7 my of continuous carbon storage in an early miocene peatland. geology, 32:873-876. maltby, e. and immirzi, p., 1993. carbon dynamics in peatlands and other wetland soils regional and global perspectives. chemosphere, 27:999-1023. meyers, p.a. and ishiwatari, r., 1993. lacustrine organic geochemistry-an overview of indicators of organic matter sources and diagenesis in lake sediments. organic geochemistry, 20:867-900. moore, s., evans, c.d., page, s.e., garnett, m.h., jones, t.g., freeman, c. and gauci, v., 2013. deep instability of deforested tropical peatlands revealed by fluvial organic carbon fluxes. nature, 493:660-663. page, s., hosciło, a., wösten, h., jauhiainen, j., silvius, m., rieley, j. and limin, s., 2009. restoration ecology of lowland tropical peatlands in southeast asia: current knowledge and future research directions. ecosystems, 12:888-905. page, s.e., banks, c.j. and rieley, j.o., 2007. tropical peatlands: distribution, extent and carbon storage-uncertainties and knowledge gaps. peatlands international, 2:26-27. page, s.e., rieley, j.o. and banks, c.j., 2011. global and regional importance of the tropical peatland carbon pool. global change biology, 17:798-818. page, s.e., rieley, j.o. and wüst, r., 2006. lowland tropical peatlands of southeast asia. developments in earth surface processes, 9:145-172. page, s.e., siegert, f., rieley, j.o., boehm, h.d.v., jaya, a. and limin, s., 2002. the amount of carbon released from peat and forest fires in indonesia during 1997. nature, 420:61-65. page, s.e., wüst, r.a.j., weiss, d., rieley, j.o., shotyk, w. and limin, s.h., 2004. a record of late pleistocene and holocene carbon accumulation and climate change from an equatorial peat bog (kalimantan, indonesia): implications for past, present and future carbon dynamics. journal of quaternary science, 19:625-635. phillips, s. and bustin, r.m., 1996. sulfur in the changuinola peat deposit, panama, as an indicator of d the environments of deposition of peat and coal. journal of sedimentary research, 66:184-196. phillips, s. and bustin, r.m., 1998. accumulation of organic rich sediments in a dendritic fluvial/lacustrine mire system at tasik bera, malaysia: implications for coal formation. international journal of coal geology, 36:31-61. posa, m.r.c., wijedasa, l.s. and corlett, r.t., 2011. biodiversity and conservation of tropical peat swamp forests. bioscience, 61:49-57. premathilake, r., epitawatta, s. and nilsson, s., 1999. pollen morphology of some selected plant species from horton plains, sri lanka. grana, 38:289-295. premathilake, r. and risberg, j., 2003. late quaternary climate history of the horton plains, central sri lanka. quaternary science reviews, 22:1525-1541. ratnayake, a.s., ratnayake, n.p., sampei, y., vijitha, a.v.p. and jayamali, s.d., 2018. seasonal and tidal influence for water quality changes in coastal bolgoda lake system, sri lanka. journal of coastal conservation, 22:1191-1199. ratnayake, a.s. and sampei, y., 2015. characterization of organic matter and depositional environment of the jurassic small sedimentary basins exposed in the northwest onshore area of sri lanka. researches in organic geochemistry, 31:15-28. 16 ratnayake, a.s., sampei, y. and ratnayake, n.p., 2019. characteristics of sedimentary organic matter and vascular plants in tropical brackish bolgoda lake, sri lanka: implications for paleoecology and chemotaxonomy. regional studies in marine science, 30:100726. ratnayake, a.s., sampei, y., ratnayake, n.p. and roser, b.p., 2017. middle to late holocene environmental changes in the depositional system of the tropical brackish bolgoda lake, coastal southwest sri lanka. palaeogeography palaeoclimatology palaeoecology, 465:122-137. rieley, j.o., wüst, r.a.j., jauhiainen, j., page, s.e., wösten, j.h.m., hooijer, a. and stahlhut, m., 2008. tropical peatlands: carbon stores, carbon gas emissions and contribution to climate change processes. in: peatlands and climate change, international peat society, pp. 148-181. rydin, h. and jeglum, j.k., 2013. the biology of peatlands. 2 nd ed., oxford university press, uk. schwark, l., zink, k. and lechterbeck, j., 2002. reconstruction of postglacial to early holocene vegetation history in terrestrial central europe via cuticular lipid biomarkers and pollen records from lake sediments. geology, 30:463-466. sjögersten, s., black, c.r., evers, s., hoyos‐santillan, j., wright, e.l. and turner, b.l., 2014. tropical wetlands: a missing link in the global carbon cycle?. global biogeochemical cycles, 28:13711386. staub, j.r. and esterle, j.s., 1994. peat-accumulating depositional systems of sarawak, east malaysia. sedimentary geology, 89:91-106. tarnocai, c. and stolbovoy, v., 2006. northern peatlands: their characteristics, development and sensitivity to climate change. developments in earth surface processes, 9:17-51. thormann, m.n. and bayley, s.e., 1997. decomposition along a moderate-rich fen-marsh peatland gradient in boreal alberta, canada. wetlands, 17:123-137. turetsky, m.r., benscoter, b., page, s., rein, g., van der werf, g.r. and watts, a., 2015. global vulnerability of peatlands to fire and carbon loss. nature geoscience, 8:11-14. volkman, j.k., rohjans, d., rullkötter, j., scholz-böttcher, b.m. and liebezeit, g., 2000. sources and diagenesis of organic matter in tidal flat sediments from the german wadden sea. continental shelf research, 20:1139-1158. wüst, r.a., bustin, r.m. and lavkulich, l.m., 2003. new classification systems for tropical organicrich deposits based on studies of the tasek bera basin, malaysia. catena, 53:133-163. xu, j., morris, p.j., liu, j. and holden, j., 2018. peatmap: refining estimates of global peatland distribution based on a meta-analysis. catena, 160:134-140. yu, z., 2011. holocene carbon flux histories of the world‟s peatlands: global carbon-cycle implications. the holocene, 21:761-774. yu, z., loisel, j., brosseau, d.p., beilman, d.w. and hunt, s.j., 2010. global peatland dynamics since the last glacial maximum. geophysical research letters, 37. gamalath, perera & bandara/journal of tropical forestry and environment vol 4, no 01 (2014) 85-96 85 environmental impact assessment of transport infrastructure projects in sri lanka: way forward i.m. gamalath 1* , h.l.k. perera 1 and j.m.s.j. bandara 1 1 department of civil engineering, university of moratuwa, sri lanka date received: 18-12-2013 date accepted: 28-04-2014 abstract environmental impact assessment (eia) was established to manage impacts on environment due to development projects and to enhance environmental quality where possible. however, recent incidents concerning several projects have aroused the question, “are we utilising eia effectively?” therefore this study was carried out to find the possible methods of improving the quality and effectiveness of eia. literature regarding eia process in sri lanka as well as in international context was reviewed together with several past eia reports related to civil engineering infrastructure projects to identify possible improvements. identified problems can be categorised mainly in to two; problems in established eia framework and methodologies adopted in impact assessment. main problems identified with regard to eia framework are lack of environmental, social protection policies and proper post monitoring plan. the problems with regard to assessment process are lack of incorporating cumulative effects and sustainability concepts in evaluation. in order to address these issues, legislature should be improved and they should focus on allocating proper weight to the eia findings in the decision process. in impact assessment, the product of magnitude of the impact and the duration of impact should be taken into account rather than just focusing on the magnitude. further analysing impacts should focus more on concepts of environmental resources and limitations rather than narrow impacts of the project. in addition to the project based eia process, strategic environmental assessment (sea) can be practised to overcome the weaknesses of the reactive nature of eia and to direct development in the right direction. keywords: assessment methodology, environmental impact assessment, impact on climate, sustainability concepts 1. introduction environmental issues are receiving high priority in the development agenda at present as humans are now suffering from neglecting those in the early stages of development. climate change and resource degradation are some of the major impacts, the world faces today. learning from past, environmental impact assessment (eia) was established to manage impacts on environment due to development projects and to enhance the environmental quality where possible. * correspondence: imgamalath@gmail.com tel: +94 7192588348 issn 2235-9370 print/issn 2235-9362 online © university of sri jayewardenepura gamalath, perera & bandara/journal of tropical forestry and environment vol 4, no 01 (2014) 85-96 86 however, recent incidents concerning several projects have aroused the question, “are we utilising eia effectively?” public question the validity of several eia as those projects have caused considerable negative impacts both at local and regional levels. they question not only the content of the reports, but the priority given to eia findings in the decision making process and the conflict of interest of institution involved in the eia process (jayawardana, 2012; kannangara, 2013). therefore this study was conducted to identify the possible methods of improving the quality of eia and enhancing its usefulness in the decision making process. literature regarding the environmental assessment (ea) and a number of eia reports were reviewed together with interviews with professionals who involved in evaluations to identify the current weaknesses and possible improvements. all these fundamental questions regarding eia arise because project implementers see the eia report just as a rubber stamp that is required to initiate their projects. hence many of the issues faced today can be solved by emphasising the advantages of the eia to the project proponent and the implementers while providing proper guidelines to follow. this paper discusses such improvements needed in the guidelines and methods needed to be adopted to enhance the effectiveness of the eia process and reap its maximum benefits. 1.2 eia inception and practice in sri lanka history eia is a widely practiced assessment or appraisal tool, which is currently used by both develop and developing countries. eia was first established in the united states in 1969 with the national environmental policy act. this was a response of the us congress to the increasing environmental damage due to the rapid development occurred during that time (jay et al., 2007). soon after its inception, it was adopted by many developed nations as all of them were facing serious environmental consequences due to industrialization (lee, 1983). the agreement of european union (eu) members in 1980s to make eia mandatory in development projects is an example (commission of the european communities, 1985). in asian context, japan, thailand and philippines are now have long established procedures while the south asian countries exist at varying levels (hennayake, 1997). eia in sri lanka the national environmental act (nea) no. 47 was enacted in 1980 in sri lanka. this was followed by amendments in 1988 and 2000; act no. 56 of 1988 and act no. 53 of 2,000 (central environmental authority, 2006). further, coast conservation act (cca), no. 57 of 1981 covers the projects coming under the cost conservation department which lies within 300 m from shore line (central environmental authority, 1998). the eia process is mandated only for prescribed projects. standard procedures and prescribed list were first based on gazettes extra-ordinary no. 772/22 of 24 th june 1993. later it was modified by gazettes extra-ordinary no. 859/14 of 23 rd february 1995, no. 978/13 of 4 th june 1997, no. 1104/22 of 05 th november 1999, no. 1108/1 of 29 th november 1999, no. 1159/22 of 22 nd november 2000 and no. 1373/6 of 29 th december 2004 (central environmental authority, 2006). further 138 industries/activities are mandated under gazette notification no. 1533/16 of 25 th january 2008 to obtain environmental protection license to maintain their activities (central environmental authority, 2009). gamalath, perera & bandara/journal of tropical forestry and environment vol 4, no 01 (2014) 85-96 87 the study helped to identify various deficiencies in the eia process in sri lankan context. problems start from the initial stage itself. since the project proponents’ (pp) desire is to commence the projects as early as possible they try to skip the eia process (wijesekara, 1999). pps manipulate the provisions in the law such as prescribed list. they make initial project proposals just under the threshold limits and expand them soon after the initial construction is completed (zubair, 2001). since the timing of the eia process has not been clearly defined in legislation, eia process (fig. 1) is usually conducted after the selection of alternatives. environmental impacts are not thoroughly considered in this alternative selection (de silva, pers. comm.). therefore eia reports are biased to the pre-selected alternatives. unfeasible alternatives are commonly used in the evaluation process to justify the preferred alternative (zubair, 2001). most of the time, not even no-option alternative is considered in the evaluation (bandara, 2001). insufficient environmental and other important data such as hydrological and geological data have hindered the evaluation process. this has led the evaluators to use unreliable secondary data in their evaluation process (de silva, pers. comm.). further, this has led to fabrication of data or sometimes to bypass the eia process by certain project proponents (zubair, 2001). use of insufficient data to evaluate impacts is common especially in the case of transport infrastructure development projects as the impacted area is wide spread; where collecting such vast data is difficult within the limited time and other resources provided for the study. though there are several guidelines for the eia process, no proper guidelines are given for evaluation or the content of the eia report in sri lanka. hence most of the time eia reports just present a list of identified possible impacts, mostly without their expected magnitude and the extent (bandara, 2001; de silva, pers. comm.). further, these impacts mainly focus on narrow, short-term and immediate impacts of individual project. impact evaluation has usually neglected the reduction of limited environmental resources, projects contribution to climate change mitigation and adaptation strategies and cumulative impacts (folkeson et al., 2013). the trend of identify only the impacts, not their magnitude has led to preparation of generic eia reports rather than site specific evaluation reports. further this makes it impossible to conduct a cost benefit analysis including costs for these mitigation measures. in addition lack of co-ordination among eia group members have led to conflicting remarks and unnecessary or repetition of information in reports (bandara, 2001). this is also due to the fact that reports only contains descriptive format. many countries, especially developing countries, lack of legal framework and policies for environmental and social protection. this has given the opportunity to pp and the evaluators to neglect some undesirable impacts and not to take necessary mitigate measures in practice (lee & george, 2000; jay et al., 2007). lack of public participation in the eia process is another issue that has been identified by past researchers (caron, 2003). even though there are regulations stipulated allowing public participation (30 days period), in most of the cases public participation in the process is not taking place at satisfactory level due to lack of understanding of the importance of the eia process among the general community. further in transport sector projects only highway related projects have been opened for public comments (bandara, 2001). monitoring and evaluation aspects are rarely addressed in the sri lankan context. all most all reports just include a section of importance of monitoring and evaluation in general. they do not include a specific plan, time line or parameters that should be monitored. gamalath, perera & bandara/journal of tropical forestry and environment vol 4, no 01 (2014) 85-96 88 fig. 1: eia procedure accordance with national environmental act of sri lanka. source: central environmental authority (2006). current legislation allows several institutions to act as project approving agencies (paa). this has caused conflict of interest in several occasions as some of these agencies act as pps for some projects (e.g. ministry of highways and ministry of power) (zubair, 2001) and this has seriously questioned the validity of such eia reports. gamalath, perera & bandara/journal of tropical forestry and environment vol 4, no 01 (2014) 85-96 89 in addition to all these problems emerges in the eia process is other decision parameters overrides the findings of the eia. financial consideration and political preference precedes environmental considerations and ultimately the eia report becomes just a document. considering all these facts the study focused on methods to improve the current practises and the quality of the eia process and content. 2. methodology literature regarding eia process in both sri lankan context and international context was reviewed together with several past eia reports in sri lanka related to civil engineering infrastructure projects (especially transport infrastructure development) to identify the changes in adopted methodologies, format and possible improvements. eia reports were reviewed focussing on the following areas.  alternatives considered  number of alternatives considered  whether no option alternative is considered  impacts considered  identified impact stages of the project  potential impacts considered in the study  methodology of assessment  quantification of impacts (quantitative/ qualitative)  weight given t o each impact for alternative analysis  details of the monitoring programme further interviews were held with professionals involved in the eia process, to identify their views and possible improvements needed in the sri lankan eia context. interviews focused on the following areas.  timing of the eia process in project life cycle  preparation of stakeholder agencies and reviewers  evaluating impacts  recommendations of the eia reports  legal enforcement and considerations  public participation all these were combined to make recommendations needed for improvement of the current eia practises. 3. results table 1 in this section reviews the content of six transport infrastructure related environmental studies. table 2 summarises the interviews held with eia experts in the country. gamalath, perera & bandara/journal of tropical forestry and environment vol 4, no 01 (2014) 85-96 90 table 1: methodologies adopted in several eia/iees in sri lanka project alternatives considered impacts considered methodology of assessment monitoring hambantota port (central engineering consultancy bureau, 2006) no option condition is considered. impacts on coastal environment, geology, hydrology, water and air quality, noise and vibration, ecology, society have been identified. impacts are considered on both construction and operational stages. only stated the quantified impacts. monitoring programmes gives frequency to monitor and critical values of parameters to be monitored. matarakataragama railway extension (department of civil engineering, university of moratuwa, 2008) six alternatives have been considered. impacts on water, habitats, earth (soil), biodiversity, aesthetics, hydrology, human interest, air & noise, transportation, economic, land use has been identified. impacts are considered on project planning, construction and operational stages. each impact has been assigned weight in eia. quantified impacts from each category by alternatives, and have been assessed in a matrix format. environmental cost benefit analysis has been performed. monitoring programme includes parameters to be monitored, frequency of monitoring, locations of monitoring and responsible agencies. new kelani bridge project (oriental consultants co. ltd, katahira & engineers international, consulting engineers and architects associated (pvt.) ltd., 2013) four alternatives have been mentioned. but only the existing situation and the selected project is assessed. impacts on socio economic, landscape, hydrology, physio-chemical environment (including global warming), and ecology has been considered. only stated the quantified impacts. extended cost benefit analysis has been performed. monitoring frequency and responsible agency has been identified. gamalath, perera & bandara/journal of tropical forestry and environment vol 4, no 01 (2014) 85-96 91 northern road connectivity project (road development authority, 2012) existing condition is described. impacts on water, habitats, earth (soil), biodiversity, aesthetics, hydrology, human interest, air & noise, transportation, economic, land use has been identified. impacts are considered on preconstruction, construction and operational stages. no descriptive monitoring programme is given. outer circular highway to colombo (oriental consultants company ltd, 2000) four alternatives been considered. impacts on hydrology, water quality, noise and vibration, air quality ecology, society, economy have been identified. alternatives are compared in matrix format considering urban, social and economic sustainability, cost factors and resettlement effects. qualitative and quantitative methods have been used. environmental cost benefit analysis has been performed. discuss institutional requirements for monitoring and frequency of monitoring. southern transport development project (road development authority, 2007) impacts on hydrology, water quality, sediment quality, air quality, noise/ground vibration, society, natural environment, earth (soil) and transport has been identified. parameters to be monitored, monitoring locations, frequency and responsible agency has been identified gamalath, perera & bandara/journal of tropical forestry and environment vol 4, no 01 (2014) 85-96 92 table 2: problems identified from the interviews focus area problems timing of the eia process in project life cycle since the timing of the eia process has not been clearly defined in legislature, eia process is usually conducted after the selection of alternatives; where environmental impacts are not thoroughly considered. preparation of stakeholder agencies and reviewers lack of expertise in the eia process among stakeholder agencies such as local authorities, have created problems in the scoping stage. during scoping stage proper boundaries for the eia evaluation is not clearly demarcated and that has created problems in the later stage of the evaluation process. further poor understanding of the eia process among the reviewers from different agencies have caused negative impact on the whole evaluation process evaluating impacts though there are several guidelines for the eia process, no guidelines are given for evaluation or the content of the eia report. hence most of the time eia reports just represent a list of identified possible impacts, not their magnitude and the extent. further these impacts mainly focus on narrow, short term and immediate impacts of individual project. the trend of identify only the impacts, not their magnitude has led to preparation of generic eia reports rather than site specific evaluation reports. recommendations of the eia reports none identifying of the magnitude has created problems in proposing suitable and necessary migratory measures. therefore most of the reports lack environmental management plan (emp) and specific recommendation to the project legal enforcement and considerations although new regulations have come up regarding water pollution and sound pollution and other physical parameters in sri lanka, this is still true for ecological, social impacts and resettlement. public participation public participation has occurred significant only on occasion where non-governmental organizations (ngo) took an interest of the project 4. discussion considering unreasonable alternatives, or neglecting alternatives (table 1 shows evaluations considering only one option) and being biased to a predetermined alternative are among usual cases because eia process usually happens after the pre-feasibility stage (as shown in the 1 st row of table 2), where various alternatives are considered and decisions are made. in that stage, usually only financial considerations are given proper attention and that could lead to selection of an alternative having considerable negative environmental impacts where more viable options are available. adopting proper policies for timing for eia and propper techniques for generating alternatives process will address this issue. examples can be seen in route planning in channel tunnel high speed rail link in uk (goodenough & page, 1994). gamalath, perera & bandara/journal of tropical forestry and environment vol 4, no 01 (2014) 85-96 93 most of the time the pps try to bypass the eia process as they see this process has a hindrance (both costly and time consuming) and just as legal requirement for the project (zubair, 2001). they do not understand the benefits that could be achieved through this assessment for themselves and the society or the region as a whole. so informing the pps about the possible economic and other benefits that they could achieve by properly conducting the eia and taking necessary migratory measures will drive them to conduct eia more rigorously. lack of expertise in the eia process has being a hindrance to the effectiveness of the eia from its inception, in developing countries (jay et al., 2007). according to the interview (as shown in 2 nd row of table 2) with the officials, though training has been given to some groups, problem occurs as they do not remain in the same institution. this is due to the institution set up in public sector in sri lanka. ultimately this leaves the project approving agencies with untrained professionals for evaluation. therefore an institution independent from typical government set up could be established to address this issue as in the case of netherlands (de silva, pers. comm.). further this will address the issue of conflict of interest, faced by several paas (zubair, 2001). according to both table 1 and table 2, it can be seen that quantifying impact is a major issue. various methods can be found in literature that can be used to address this issue (pastakia & jensen, 1998; bonachea, et al., 2005). however, even when impacts are quantified (3 cases in table 1) they are mainly quantified based on the magnitude of the impact only. this may lead to assigning high priority to large scale short term impact/s which could not be so critical in the long run. therefore when quantifying the impacts, multiplication of the magnitude and the duration of the impact should be considered. in impact assessment, proper attention should be given to the impacts to climate change and resource degradation that are caused by the proposed development. greenhouse gas emission is caused not only by the fossil fuel combustion but by land use changes also (karl & trenbirth, 2003). therefore it is at great importance to quantify such impacts (bristow & nellthorp, 2000; pielke-sr, et al., 2002; fuglestvedt, et al., 2010; uherek, et al., 2010). row 3 of table 1 presents a local example for the new kelani bridge. further, alternatives could be evaluated based on the resilience to these impacts and the possible increase of mitigation and adaptation capabilities of communities. these aspects should be given proper attention specially in transport development projects as this sector contributes considerable fraction of greenhouse gas emissions (chapman, 2007). proper legal framework should be established to address the issues regarding ecological (geneletti, 2003) and social protection. lessons can be learnt from developed countries such as netherlands and united states where they have successfully implemented such system (swell, 1996).further, legal framework should be improved to include the content of the eia report (de silva, pers. comm.). this is to avoid the misuse of such absence and not including quantified impacts, migratory methods and follow up programmes with specific objectives and time lines. further these improvements should address the conflict of interest of certain paas. in addition to the project based eia process, strategic environmental assessment (sea) can be practised to overcome the inherent weaknesses of the reactive nature of eia and to direct development in the right direction, by considering cumulative effects (cooper & sheate, 2002). however, proper coordination among various development agencies and local authorities is essential in this matter, as sri lanka is failing in this attempt due to the same fact (de silva, pers. comm.). gamalath, perera & bandara/journal of tropical forestry and environment vol 4, no 01 (2014) 85-96 94 5. conclusions based on the review of sri lankan eia reports following steps can be made to improve the eia process. establishment of proper guidelines are essential for the stages (at which phase of project design) which the eia practises should be adopted. quantification of the impacts should be based on the multiplication of the magnitude and the duration of impact and also impacts quantification should be done on climate change and resource degradation. moreover, alternatives should be evaluated based on the resilience to climate impacts and the possible increase of the mitigation and adaptation as a society and assigning a proper weight to environmental impacts in alternative analysis in feasibility and eia activities is also essential. based on results from interviews held, establishment of an independent institution for project approving following measures and improvement of the legal framework for better social and ecological protection and to ensure detail monitoring and evaluation process can be suggested as improvements. acknowledgement authors acknowledge the support of prof (mrs) nilanthi bandara, mrs. kanthi de silva (director eia of central environmental authority) and mr. h.m.k.g.g. bandara (director planning road development authority) in this study. references bandara, j., 2000. issues related to transport sector environmental impact assessments (eia): experience in sri lanka. proceedings of the seventh annual forestry and environmental symposium 2001 of the department of forestry and environmental science university of sri jayewardenepura, sri lanka, p.40. bonachea, j., bruschi, v. m., remondo, j., gonzález-díez, a., salas, l., bertens, j., aramburu, j. m., 2005. an approach for quantifying geomorphological impacts for eia of transportation infrastructures: a case study in northern spain. geomorphology, 66:95–117. bristow, a., nellthorp, j., 2000. transport project appraisal in the european union. transport policy, 7:51–60. caron, c. m., 2003. defining the public interest, negotiating rights: the influence of environmental impact assessment legislation in sri lanka. 9th international conference on sri lanka studies. matara. central engineering consultancy bureau, 2006. environmental impact assessment of the proposed hambanthota port project. draft final report. central environmental authority, 1998. simple questions and answers on environmental impact assessment (eia). central environmental authority. central environmental authority, 2009. environmental protection licence. central environmental authority. central environmental authority, 2006. guidance for implementing the environmental impact assessment (eia) process; no: 1 a general guide for project approving agencies (paa) (4th ed.). central environmental authority. central environmental authority, 2006. guidance for implementing the environmental impact assessment (eia) process; no: 2 a general guide for conducting environmental scoping (3rd ed.). central environmental authority. gamalath, perera & bandara/journal of tropical forestry and environment vol 4, no 01 (2014) 85-96 95 chapman, l., 2007. transport and climate change: a review. journal of transport geography, 15:354-367. commission of the european communities, 1985. council directive of 27 june 1985 on the assessment of effects of certain public and private projects on the environment. official journal of the european communities, l175:40-48. cooper, l., sheate, w., 2002. cumulative effects assessment: a review of uk environmental impact statements. environmental impact assessment review, 22:415–439. de silva, k. personnel communication. director eia, central environmental authority, sri lanka. department of civil engineering, university of moratuwa, 2008. environmental impact assessmentmatara kataragama railway extension. folkeson, l., antonson, h., heedin, j., 2013. planners' views on cumulative effects. a focus group study concerning transport infrastructure planning in sweden. land use policy, 30:243-253. fuglestvedt, j., shine, k., berntsen, t., cook, j., lee, d., stenke, a., waitz, i., 2010. transport impacts on atmosphere and climate: metrics. atmospheric environment. 44:4648–4677. geneletti, d., 2003. biodiversity impact assessment of roads: an approach based on ecosystem rarity. environmental impact assessment review, 23:343–365. goodenough, r.a., page, s.j., 1994. evaluating the environmental impact of a major transport infrastructure project: the channel tunnel high-speed rail link. applied geography, 14:26-50. jay, s., jones, c., slinn, p., wood, c., 2007. environmental impact assessment: retrospect and prospect. environmental impact assessment review. 27:287-300. jayawardana, d., 2012. sethusamudram and its impact on sri lanka. http://www. dailymirror.lk/business/features/18501-sethusamudram-and-its-impact-on-sri-lanka. html. accessed september 27, 2013. kannangara, n., 2013. mattala international airport in mid-air battle. http://www. thesundayleader.lk/2013/03/31/mattala-international-airport-in-mid-air-battle/. accessed on december 9, 2013, karl, t., trenbirth, k., 2003. modern global climate change. science, 302:1719-1723. lee , n., george, c., 2000. environmental assessment in developing and transitional countries. wiley, chiichester. lee, n., 1983. environmental impact assessment: a review. applied geography. 3(1):5-27. oriental consultants company ltd., 2000. the study on the outer circular highway to the city of colombo; volume 5 environmental and social impact assessment. oriental consultants co. ltd, 2013. proposed the second new kelani bridge project: environmental impact assessment. pastakia, c., jensen, a., 1998. the rapid impact assessment matrix (riam) for eia. environmental impact assessment review, 18:461-482. pielke-sr, r., marland, g., betts, r., chase, t. n., eastman, j., niles, j., running, s., 2002. the influence of land-use change and landscape dynamics on the climate system: relevance to climate-change policy beyond the radiative effect of greenhouse gases. the royal society, 1705-1719. roads development authority, 2007. environmental management plan for southern transport development project. roads development authority, 2012. initial environmental examination, sri lanka: northern road connectivity project: additional financing. gamalath, perera & bandara/journal of tropical forestry and environment vol 4, no 01 (2014) 85-96 96 swell, c. g., 1996. conflicting benefits: national implementation of the united nations framework convention on climate change. environmental impact assessment review, 16:137-150. uherek, e., halenka, t., borken-kleefeld, j., balkanski, y., berntsen, t., borrego, c., schmid, s., 2010. transport impacts on atmosphere and climate: land transport. atmospheric environment, 44:4772–4816. wijesekara, n., 1999. present day needs in environmental impact assessment evaluation the ukhp of sri lanka, an example of the challenge. proceedings of the first annual south asian environmental assessment. kathmandu, nepal: the world conservation union, pp.130-145. zubair, l., 2001. challenges for environmental impact assessment in sri lanka. environmental impact assessment review. 21:469-478. title (font-times new roman, size-16, bold, center) kinyili et al./ journal of tropical forestry and environment vol. 10, no. 01 (2020) 87-100 87 influence of agroforestry on rural income and livelihood of smallholder farmers in the semi-arid region of sub saharan africa b.m. kinyili 1 *, e. ndunda 2 and e. kitur 2 1 kenya forest services, eldoret, kenya 2 department of environmental science, kenyatta university, nairobi, kenya date received: 23-06-2019 date accepted: 30-04-2020 abstract semi-arid lands typically suffer from sustainable land use challenges including climate variability, declining agricultural productivity, low economic prowess and poor livelihood conditions. in order to sustainably address these challenges, agroforestry has been fronted as a critical entry point allowing for the integration of trees on farms and diversification of production in agricultural landscapes. nevertheless, the contribution of agroforestry to socio-economic and rural livelihood in several developing countries remains debatable. this study determined the influence of agroforestry on rural income and livelihood of smallholder farmers in machakos county (kenya). the study was conducted using survey research design from a sample of 248 smallholder farmers, who were selected using stratified, random sampling. data were collected using questionnaires and interviews. results showed that agroforestry was adopted by 82% of the smallholder farmers as a strategy for livelihood improvement in the region. total income was higher among adopters from timber, fuel wood, posts/poles and fodder. adopters also had more money to spend on food, clothing, education, medicine and basic needs as a result of revenues from agroforestry. the overall gross revenue, net returns above variable costs and total costs were also higher among adopters compared to the non adopters due to sales of agroforestry products. the study recommends adoption of agroforestry as a strategy to boost rural income and livelihood. keywords: agroforestry, socio-economic, rural income and livelihood, machakos, sub saharan africa 1. introduction globally, dryland areas characterised by low moisture content due to low rainfall and high rates of evaporation, and a gradient of low agricultural productivity, comprise of approximately 100 countries and cover 42% of the global surface landmass (6.4 billion ha) (prăvălie 2016; bastin et al., 2017; prăvălie et al., 2019). despite the wide coverage, concern have been raised on human conditions in dryland environments in africa, calling for significant development assistance and frequent humanitarian aid (de leeuw et al., 2014). the gravity of the situation in drylands of africa is clearer since it account for nearly 400 million people who live and derive their livelihood in these areas (aleman et al., 2018; gaur and squires, 2018). the situations within the dryland areas are being orchestrated by innumerable challenges such as climate variability, frequent drought, natural resources degradation, declining agricultural productivity and high population increment (syano et al., 2016). therefore, there is a consensus that most of the agro-based activities within these landscapes must be geared towards solving foreseeable challenges (krishnamurthy et al., 2019). agroforestry as a dynamic, ecologically based natural resources management system, integrates trees on farms and in agricultural landscapes has been under consideration as an integral component of dryland regions(ceperley et al., 2016). __________________________________ *correspondence: bmkinyili@yahoo.com tel: +25 4723393737 ©university of sri jayewardenepura doi: https://doi.org/10.31357/jtfe.v10i1.4691 88 the multiple perceived benefits and merits of agroforestry for providing environmental benefits, economic products and social goods are well known and widely recognised (franzel, 2004; jose, 2009; fanish and priya, 2013; gao et al., 2014). in rural households, trees can be used as sources of food, fuel, fodder, construction materials, medicine, to meet subsistence needs (adekunle and bakare, 2004; kumar and thakur, 2017; jemal et al., 2018). historically, agroforestry was narrowly defined in terms of their subsistence production (somarriba, 1992) but currently seen in light of economic terms stressing the enhancement of the economic return of the system (kareem et al., 2016; mercer et al., 2017; paul et al., 2017; bruck et al., 2019). in light of recurring food shortages, and rising prices of fossil fuel-based agricultural inputs, economic benefits of agroforestry has recently experienced a surge in interest from the research communities, especially in developing countries (amejo et al., 2018). in africa, agroforestry is currently practiced by many smallholder farmers (mbow et al., 2014) where there has been increasing adoption by farmers particularly in the sub saharan africa (franzel et al., 2001; leakey et al., 2005; meijer et al., 2015; beyene et al., 2019). adoption of agroforestry is still rampant despite the persistent attempts at introducing monoculture crop production (djurfeldt et al., 2005; altieri et al., 2012). many of the residents view the option of integrating and managing trees with crops and livestock on the same landscape as an opportunity cost representing a conscious investment due to goods and services derived from the practice (amare et al., 2019). the suits of goods and services derived from the practice of agroforestry include firewood, building materials (posts and timber), food such as fruits, medicine and invaluable environmental services (wulan et al., 2008; kimaro et al., 2019). in rural areas, other additional non-timber products include beeswax, honey, edible fruits, edible insects, wild vegetable, game meat, traditional medicines and fibres, estimated to boost annual income of households (leakey et al., 2005; kalaba et al., 2010). consequently, the insight that trees on farms improve the socio-economic prospects and provide livelihood benefits is increasingly being recognised in the sub saharan african region (kalaba et al., 2010; quandt et al., 2018). profitability of the various agroforestry practices has been analysed by various workers and the results show large degree of variation among research as to the overall socio-economic and livelihood impacts (kang and akinnifesi, 2000; roshetko et al., 2007; steffan-dewenter et al., 2007; akinnifesi et al., 2008). nevertheless, in several drylands of developing countries especially in the sub saharan africa, studies addressing contribution of agroforestry to socio-economic status and rural livelihood are limited (jama et al., 2006; iiyama et al., 2014) and therefore may be inconclusive. therefore more studies on agroforestry adoption and socio-economic conditions are needed. the aim of this study was to determine the influence of agroforestry adoption on the rural income and livelihood in machakos county in kenya within the tropical region. 2. methodology 2.1 the study area the study was conducted in machakos county (figure 1) which covers an area of 5,953 km². it lies between latitudes 0 o 45 / south and 1 o 31 / south and longitudes 36 o 45 / east and 37 o 45 / east. most of the land is semi-arid with population of 1,098,584 as per the 2009 kenya national census (kenya national bureau of statistics, 2010). administratively the county is divided into 11 divisions: kalama, kangundo, kathiani, machakos central, masinga, matungulu, mavoko, mwala, ndithini, yathui and yatta. in terms of political structure, the county has eight constituencies including: kangundo, kathiani, machakos town, masinga, matungulu, mavoko, mwala and yatta. there are overlaps between divisions and constituencies were they are in most cases referred to as sub-counties. among the division and constituencies, kathiani, mavoko and machakos town practice agrofostry. four siteswhere kinyili et al./ journal of tropical forestry and environment vol. 10, no. 01 (2020) 87-100 89 agroforestry are practiced included: mua (mavoko, machakos town and kathiani) and iveti hills (machakos central and kathiani), kima-kimwe and kalama in machakos constituency. figure 1. map of machakos county showing the study area, kenya. the local climate is semi-arid with hilly terrain and an altitude of 1,000 to 2,100 m above sea level. the area is composed of hilltops rising to 1,594-2,100 m above sea level. the annual average rainfall is 1,000 mm (range, 500 to 1,300 mm), and is bimodal; short rains occur in october to december and long rains in march to may. temperatures range between 18.7 o c and 29.7 o c. the soils are well drained shallow dark red volcanic on hilltops and clay soils in the plains. irrigation farming is practiced utilising the permanent rivers and streams that flow from the hilltop catchment areas towards south eastern to join athi river. crop such as maize, beans, pigeon peas, vegetables are dominant. dairy and beef cattle, sheep, and goats are the major livestock kept. 2.1 data collection this study was conducted through an exploratory survey design. surveys are normally used to systematically gather factual quantifiable information necessary for decision-making (nardi, 2018). surveys are efficient methods of collecting descriptive data regarding the characteristics of populations, current practices and conditions or needs. they also help gather information from large populations by employing use of samples hence cutting down on costs. survey study research design was adopted in this study in order to capture descriptive data from selected samples and generalise the findings to the populations from which the sample was drawn. the study targeted household heads from mua hills (mavoko, machakos town and kathiani), iveti hills (machakos central and kathiani), kima-kimwe and kalama hills in machakos constituency. the sample size of the households adopting agroforestry as earlier established in the region was used. according to (nzilu, 2015), 80% of the households had adopted agroforestry in mwala (machakos county). the appropriate sample size was computed using the formula described in mugenda and mugenda (mugenda and mugenda, 2003) (equation 1). 90 where: n=the desired sample size z=the z score at the required confidence level α=0.05 (1.96) p=the proportion in the target population assumed to be adopter d=permissible marginal error (the level of statistical significance, set at α=0.05). using the values of z, p and d, the value of n was computed as follows (equation 2). the sample size was 246 but the two research assistants who hail from the area also provided additional information resulting in a total of 248 respondents. adopters who were included in the study were households practicing any form of agroforestry while non adopters were those who had no form of agroforestry or tree growing in their farms. samples were selected through stratified, random sampling at each of the selected spatial units and used to identify the adopters and non adopters. this study relied on primary type of data. primary data on income, expenditure and rural livelihood among the respondents was collected using structured researcher administered questionnaires. the designing of the instruments were such that they ensured an in-depth exploration of personal views, feelings and opinions on agroforestry and benefits accrued. before data collection, the respondents were contacted in advance and asked to organize their time for the research. two research assistants were recruited and trained to aid in data collection. the questionnaires were administered by physical drop and pick by the researcher and two research assistants. the researcher personally administered the instrument and made prior visits to assist in defining timings and distribution of research instruments. research instruments were developed by examining the aim of the research. the validity of the instruments was sought through expert judgment who examined the face, content and construct validities in order to determine whether items measured what they were supposed to determine. they established whether the numbers of items are adequate for the purpose intended research and thus their expert judgments ensured validity of the instruments. the reliability of the instruments was established through a pilot study of 12 household members from the study area who did not participate in this study. the results of the study were used to compute the reliability of the instruments through cronbach’s coefficient alpha (bonett and wright, 2015). the study considered the instrument as reliable and acceptable if the computation yielded a reliability coefficient of 0.7 and above. for this study, the reliability coefficient was 0.83 which was suitable for research. all questionnaire data were coded into statistical package for social sciences (spss 23) for analysis. differences in rural income, expenditure and livelihood were evaluated using chi-square analysis and anova. all analyses were declared significant at p<0.05. 3. results the socio-economic profile of the respondents in machakos county during the study is shown in table 1. majority of the respondents were aged 36-55, most being females with primary and secondary 2 2 )1( d ppz n   24686.245 05.0 )8.01(8.096.1 2 2   n (1) (2) kinyili et al./ journal of tropical forestry and environment vol. 10, no. 01 (2020) 87-100 91 levels of education. household size for the majority was 6-10. the land size ranged between 0.4 to 24 acres with majority having land size ranging between 2-5 acres followed by those with less than 2 acres. table 1: socio-economic profiles of the respondents. agroforestry adopters agroforestry non adopters variable response category frequency (n=204) percent (%) frequency (n=44) percent (%) age (years) 18-25 11 5.4 6 6.9 26-35 28 13.7 8 18.2 36-55 84 41.2 14 31.8 >55 81 39.1 16 36.4 gender female 116 56.9 26 59.1 male 88 43.1 18 40.9 marital status single 12 5.9 1 2.3 married 192 94.1 43 97.7 level of education none 5 2.5 7 15.9 primary 112 54.9 18 40.9 secondary 73 35.8 14 31.8 tertiary 14 6.8 5 11.4 household size <3 3 1.5 0 0.0 3-5 75 36.8 27 61.4 6-10 105 51.5 17 38.6 >10 21 10.3 0 0.0 land size <2 acre 72 35.3 14 31.8 2-5 acres 106 52.0 26 59.1 5.1-10 acres 26 12.7 4 9.1 the computed average income from crops, livestock and total income from the adopters and non adopters of agroforestry in machakos are provided in table 2. the income derived from crop, livestock, tree seedlings and tree products as well as the farm and total income of the farmers were all significantly higher for the adopters than non adopters (p<0.05). table 2: average income from crops, livestock and total income computed between adopters and non adopters of agroforestry in machakos (values are in us $). income adopters non adopters t value p value average annual farm income from crop proceeds * 278.39 154.16 30.1281 0.0000 average annual farm income from livestock * 228.38 156.05 9.531 0.0021 average annual income from tree seedlings * 205.18 109.83 17.391 0.0001 average income from wood/wood products * 271.34 142.91 16.680 0.0001 average farm income per annum * 253.44 195.61 5.985 0.0056 total income from agroforestry * 1236.73 758.56 60.104 0.0000 * differences are significant at p<0.05 ns denotes not significantly different the average income wood and wood products from the adopters and non adopters of agroforestry in machakos are provided in table 3. the income derived from timber and fuel wood as well as the total income derived from wood/wood products was significantly higher for the adopters than non adopters 92 (p<0.05). however, the income derived from posts/poles and from fodder was similar for the adopters and non adopters. table 3: income derived from wood and wood products between the adopters and non adopters in machakos county (values are in us $). wood income adopters non adopters t value p value income realised annually from timber * 162.00 77.73 14.088 0.0000 income realised annually from fuelwood * 96.06 67.15 3.184 0.0413 income realised annually from post/poles ns 60.16 53.61 0.248 0.6193 income realised annually from fodder ns 63.00 64.72 0.005 0.9546 total annual income from wood/wood products * 271.34 142.91 16.680 0.0001 * differences are significant at p<0.05 ns denotes not significantly different annual expenditure on basic needs adopters and non adopters of agroforestry in machakos county are shown in table 4. the annual expenditure on food, clothing, education, medicine and total household expenditure on basic needs were all significantly higher for the adopters than non adopters (p<0.05). table 4: annual expenditure on basic needs between adopters and non adopters of agroforestry in machakos county (values are in us $). expenditure on basic needs adopters non adopters t value p value annual household expenditure on food * 222.27 86.82 74.954 0.0000 annual household expenditure on clothing * 157.02 69.89 62.944 0.0000 annual household expenditure on education * 206.28 151.09 11.389 0.0014 annual household expenditure on medicine * 92.42 57.55 9.304 0.0034 annual household expenditure on basic needs * 646.55 329.52 111.851 0.0000 * differences are significant at p<0.05 ns denotes not significantly different the annual expenditure budget for wood and wood products between adopters and non adopters are shown in table 5. the household annual expenditure on timber, poles as well as the total expenditure on wood and wood products was significantly higher for the non adopters than adopters (p<0.05). table 5: annual expenditure budget for wood and wood products between adopters and non adopters. (values are in us $). wood/wood product expenditure category adopters non adopters t value p value household annual expenditure on timber * 71.00 164.62 4.276 0.0225 household annual expenditure on fuel wood * 45.81 49.91 0.4254 0.0432 household annual expenditure on poles/posts ns 50.09 52.30 0.0452 0.8323 household annual expenditure on fodder ns 31.03 37.51 2.796 0.3422 total expenditure on wood/wood products * 199.93 302.34 10.672 0.0001 * differences are significant at p<0.05 ns denotes not significantly different the enterprise budget for adopter and non adopters of agroforestry practices in machakos county are shown in table 6. based on the table, gross revenue for the adopters (us $ 1,236.73) was higher than the non adopters (us $ 758.56). also the overall expenditure on variable cost by the adopters (us $ 890.16) was consistently higher than the non adopters (us $ 663.86). the total fixed cost of the kinyili et al./ journal of tropical forestry and environment vol. 10, no. 01 (2020) 87-100 93 agroforestry adopters was nevertheless similar to the non adopters (us $ 70.80). as a consequence, there were higher net returns above total variable costs (tvc) for the adopters (us $ 346.57) compared to the non adopters (us $ 94.70), which resulted in positive higher net returns above total cost (tc) for the adopters (us $ 275.77) compared to the non adopters (us $ 23.90). the computed margins above tvc (%) was therefore higher for the agroforestry adopters (28.02%) than the non adopters (12.48%) and margins above the total cost for the adopters was 22.30% and 3.15% for the non adopters. table 6: computed enterprise budget for adopter and non adopters of agroforestry practices in machakos county (values are in us $). parameters adopters non adopters revenues average annual farm income from crop proceeds 278.39 154.16 average annual farm income from livestock 228.38 156.05 average annual income from tree seedlings 205.18 109.83 average annual income from wood/wood products 271.34 142.91 average annual farm income per annum 253.44 195.61 total income from agroforestry 1236.73 758.56 variable costs household expenditure on food per year 222.27 86.82 annual household expenditure on clothing 157.02 69.89 annual household expenditure on education 206.28 151.09 annual household expenditure on medicine 92.42 57.55 total annual household expenditure on basic needs 646.55 329.52 household annual expenditure on timber 71.00 164.62 household annual expenditure on fuel wood 45.81 49.91 household annual expenditure on poles/posts 52.09 50.30 household annual expenditure on fodder 31.03 37.51 total expenditure on wood/wood products 199.93 302.34 miscellaneous 43.68 32.00 total variable cost (tvc) 890.16 663.86 fixed costs amortisation 60.00 60.00 interest on fixed cost 10.80 10.80 total fixed cost 70.80 70.80 total cost (tc) 960.96 734.66 net returns above tvc 346.57 94.70 net returns above tc 275.77 23.90 margins above tvc (%) 28.02 12.48 margins above tc (%) 22.30 3.15 the indicators of improved livelihood among the adopters and non adopters of agroforestry were also determined (table 7). there were significant differences in the responses to the contribution of agroforestry to livelihood between the adopters and non adopters ( 2 =45.2312, df=8, p<0.001). among the adopters of agroforestry, majority attested that indeed there was increased food supply, improved educational attendance and increased energy in the household. 94 table 7: indicators of improved livelihood among adopters of agroforestry. livelihood indicators adopters non adopters frequency percent (%) frequency percent (%) reduced use of fertilizers 168 82.4 15 34.1 increased energy in the household 174 85.3 17 38.6 increased food supply 178 87.3 11 25.0 increased household income 124 60.8 15 34.1 improved educational outcomes 101 49.5 15 34.1 improved medical attendance 78 38.2 12 27.3 improvement in employment 122 59.8 8 18.2 improved educational attendance 177 86.8 11 25.0 increase in land sizes 106 52.0 7 15.9 the scores of the indicators of household livelihoods was also determined among the adopters and compared with the non adopters. the results are as shown in figure 2. based on the scores from the figure, there were consistently higher rank scores for all the livelihood indicators among adopters compared to the non adopters except for improved educational outcomes, improved medical attendance, and increased land sizes. figure 2. scores of the indicators of household livelihoods among adopters and non adopters in machakos county. 0 20 40 60 80 p e rc e n t ra n k s c o re s o f th e r e sp o n se s indicator of livelihood adopters non adopters kinyili et al./ journal of tropical forestry and environment vol. 10, no. 01 (2020) 87-100 95 4. discussion during the study, the income derived from crop, livestock, tree seedlings and tree products as well as the farm and total income of the farmers were higher for the adopters than non adopters. this concurs with other studies which indicated that earning from crops, livestock and trees among agroforestry adopters is often higher owing to the income earned from sales of the crops, livestock and trees from the agroforestry (neupane and thapa, 2001; franzel, 2004; namwata et al., 2012; kareem et al., 2016; kassie, 2018). indeed agroforestry increase livelihood benefits for people such as food security, employment, income generation among others. meanwhile the average annual farm income from livestock proceeds displayed significant differences since it was established that agroforestry adopters did keep higher number of animals than those not practicing agroforestry and therefore the earnings from livestock were similar. the study also established a higher income from timber, fuel wood and wood/wood products due to agroforestry adoption which concurs with several other studies (scherr, 2004; bertomeu, 2006). apart for domestic use of the timber and fuel wood, there are instances where farmers with larger scale practice of agroforestry can sell some of their products and earn income higher than those without any form of agroforestry. nevertheless the income derived from posts/poles and from fodder were similar for the adopters and non adopters which may be attributed to low production of these wood products among farmers and the fact that they do not sell posts/poles and fodder. the annual expenditure on food, clothing, education, medicine and total household expenditure on basic needs were all significantly higher for the adopters than non adopters due to the higher disposal income from agroforestry that enabled them spend more on food, clothing, education and medicine. given one of the largest costs of most rural areas is on fuel wood as a source of energy (sharma et al., 2016; waldron et al., 2017), most of the farmers with trees in their farms will save the income and use it to purchase food, built better houses and spend more on quality education as well as search for better healthcare (borish et al., 2017). the household annual expenditure on timber, poles as well as the total expenditure on wood and wood products was significantly higher for the non adopters than adopters which concurs with other studies (leakey et al., 2005) due to the fact that most of the adopters have these products in their farms and therefore they don’t need to buy these products from outside their farms. during adoption of agroforestry, farmers have access to wood and wood products and therefore the amount of money going towards purchase of such are expected to be lower than those who have no wood from any agroforestry practice. however, expenditure on fodder was not different between the adopters and the non adopters mainly because most of the agroforestry practices were not planting fodders in their farms. analysis of enterprise budget yielded several observations. first the gross revenue for the adopters (us $ 1,236.73) was higher than the non adopters (us $ 758.56) indicating higher income derived from agroforestry practices. similarly the overall expenditure on variable cost by the adopters (us $ 890.16) was consistently higher than the non adopters (us $ 663.86) which was attributed to the adopters having higher disposal incomes. the total fixed cost of the agroforestry adopters was nevertheless similar to the non adopters (us $ 70.80) suggesting that fixed cost for the adopters and non adopters tend to be somewhat similar. as a consequence, there were higher net returns above tvc for the adopters (us $ 346.57) compared to the non adopters (us $ 94.70), which resulted in positive higher net returns above tc for the adopters (us $ 275.77) compared to the non adopters (us $ 23.90). based on the above statistics, the computed margins above tvc (%) was therefore higher for the agroforestry adopters (28.02%) than the non adopters (12.48%) and margins above the total cost for the adopters was 22.30% and 3.15% for the non adopters. these results suggest that income was higher for the adopters resulting in overall profitable operational margins that render adoption as a good enterprise. 96 this study also determined the influence of adoption of agroforestry practices on rural livelihood of smallholder farmers and found that adopters of agroforestry had increased food supply, improved educational attendance and increased energy in the household, which concurs with several studies among agroforestry adopters (quandt and mccabe 2017; quandt et al., 2018). the diversification of crops, keeping of livestock and trees in the same farm which can be sold by the farmers is expected to create opportunities for achieving a steady and sometimes higher rural income through the more efficient use of resources and the exploitation of comparative advantages (kassie 2018). agroforestry systems have also been determined to combine short-term and long-term benefits for the farm households with the aim of livelihood protection and sustainability in the use of resources in semi arid areas (quandt et al., 2017). the mango-based alley cropping that was practiced by majority of the farmers played a vital role in rural livelihood strategies. the scores of the indicators of household livelihoods were consistently higher rank scores for all the livelihood indicators among adopters compared to the non adopters except for improved educational outcomes, improved medical attendance, and increased land sizes. improvement of livelihood among agroforestry adopters have been identified in several studies. the land use systems in the study area are generally agro-crop production along with timber and fruit tree species and livestock production systems. here, the farmers practice agroforestry include woodlot, alley cropping, windbreaks/shelterbelts and intercrop. most of the farmers intercropped grain, vegetables and tree crops. the grain crops cultivated in the land use system included maize, bean, millet, sorghum, pigeon peas, peas, green chili, etc. with horticultural produce such as avocado, carrot, kales, oranges, mangoes, pawpaw, onions, tomatoes, cabbages, gourd, bitter gourd, pumpkin, and pineapple, which are often sold to increase livelihood indices. nevertheless it was found that income generating activities in the study area were not diversified as compared to other regions of the world (burgess et al., 2017; mosqueralosada et al., 2018). from above results, it is clear that agroforestry plays a major role in supporting the socio-economic needs and improving the livelihood conditions of the people in machakos, kenya. 5. conclusion the study shows that in the dryland area of machakos in kenya, adoption of agroforestry improved the socio-economic and livelihood indicators of the local communities by enhancing income and expenditure. agroforestry adoption generated more money to adopters to send their children to schools, buy medicine, buy clothes and other necessities that eventually improved the livelihood. it can be concluded that agroforestry adoption had a significant impact on the livelihood of most agroforestry adopters and their households acknowledgment the kenya organization for environmental education (koee) through faith based climate change education for sustainable development (fbccesd) financed this study while kenya agricultural and livestock research organization (kalro) helped in providing information on areas with previous agroforestry projects. the kenya forest service (kfs) assisted in identification of active agroforestry adopters who participated in this study. we thank the local community members who agreed to sacrifice their time to respond to the questionnaires. references adekunle, v.a. and bakare, y., 2004. rural livelihood benefits from participation in the taungya agroforestry system in ondo state of nigeria. small-scale forest economics, management and policy, 3:131-138. kinyili et al./ journal of tropical forestry and environment vol. 10, no. 01 (2020) 87-100 97 akinnifesi, f., chirwa, p., ajayi, o., sileshi, g., matakala, p., kwesiga, f., harawa, h. and makumba, w., 2008. contributions of agroforestry research to livelihood of smallholder farmers in southern africa: 1. taking stock of the adaptation, adoption and impact of fertilizer tree options. agricultural journal, 3:58-75. aleman, j.c., jarzyna, m.a., and staver, a.c., 2018. forest extent and deforestation in tropical africa since 1900. nature ecology and evolution, 2:26. altieri, m.a., funes-monzote, f.r. and petersen, p., 2012. agroecologically efficient agricultural systems for smallholder farmers: contributions to food sovereignty. agronomy for sustainable development, 32:1-13. amare, d., wondie, m., mekuria, w. and darr, d., 2019. agroforestry of smallholder farmers in ethiopia: practices and benefits. small-scale forestry, 18:39-56. amejo, a.g., gebere, y.m. and kassa, h., 2018. integrating crop and livestock in smallholder production systems for food security and poverty reduction in sub-saharan africa. african journal of agricultural research, 13:1272-1282. bastin, j.-f., berrahmouni, n., grainger, a., maniatis, d., mollicone, d., moore, r., patriarca, c., picard, n., sparrow, b. and abraham, e.m., 2017. the extent of forest in dryland biomes. science, 356:635-638. bertomeu, m., 2006. financial evaluation of smallholder timber-based agroforestry systems in claveria, northern mindanao, the philippines. small-scale forest economics, management and policy, 5:57-81. beyene, a.d., mekonnen, a., randall, b. and deribe, r., 2019. household level determinants of agroforestry practices adoption in rural ethiopia. forests, trees and livelihoods, 1-20. bonett, d.g. and wright, t.a., 2015. cronbach's alpha reliability: interval estimation, hypothesis testing, and sample size planning. journal of organizational behavior, 36:3-15. borish, d., king, n. and dewey, c., 2017. enhanced community capital from primary school feeding and agroforestry program in kenya. international journal of educational development, 52:10-18. bruck, s.r., bishaw, b., cushing, t.l. and cubbage, f.w., 2019. modeling the financial potential of silvopasture agroforestry in eastern north carolina and northeastern oregon. journal of forestry, 117:13-20. burgess, p., herder, m.d., moreno, g., pantera, a., kanzler, m., hermansen, j., palma, j., plieninger, t., kay, s. and mosquera-losada, r., 2017. agroforestry in europe. practice, research and policy. third national agroforestry conference. ceperley, n., mande, t., van de giesen, n., tyler, s. and parlange, m., 2016. assessment of agroforestry trees in dry-land savanna supports ecohydrologic separation. egu general assembly conference abstracts. de leeuw, j., njenga, m., wagner, b. and iiyama, m., 2014. treesilience: an as. by: the world agroforestry centre (icraf), nairobi, kenya. djurfeldt, g., holmen, h., jirstrom, m. and larsson, r., 2005. the african food crisis: lessons from the asian green revolution. cabi. fanish, s.a. and priya, r.s., 2013. review on benefits of agroforestry system. international journal of education and research, 1:1-12. franzel, s., 2004. financial analysis of agroforestry practices. valuing agroforestry systems, springer, pp 9-37. franzel, s., coe, r., cooper, p., place, f. and scherr, s., 2001. assessing the adoption potential of agroforestry practices in sub-saharan africa. agricultural systems, 69:37-62. gao, j., barbieri, c. and valdivia, c., 2014. a socio-demographic examination of the perceived benefits of agroforestry. agroforestry systems, 88:301-309. 98 gaur, m.k. and squires, v.r., 2018. climate variability impacts on land use and livelihoods in drylands. springer iiyama, m., neufeldt, h., dobie, p., njenga, m., ndegwa, g. and jamnadass, r., 2014. the potential of agroforestry in the provision of sustainable woodfuel in sub-saharan africa. current opinion in environmental sustainability, 6:138-147. jama, b., elias, e. and mogotsi, k., 2006. role of agroforestry in improving food security and natural resource management in the drylands: a regional overview. journal of the drylands, 1:206-211. jemal, o., callo-concha, d. and van noordwijk, m., 2018. local agroforestry practices for food and nutrition security of smallholder farm households in southwestern ethiopia. sustainability, 10:2722. jose, s., 2009. agroforestry for ecosystem services and environmental benefits: an overview. agroforestry systems, 76:1-10. kalaba, k.f., chirwa, p., syampungani, s. and ajayi, c.o., 2010. contribution of agroforestry to biodiversity and livelihoods improvement in rural communities of southern african regions. tropical rainforests and agroforests under global change, springer, pp 461-476. kang, b. and akinnifesi, f., 2000. agroforestry as alternative land‐ use production systems for the tropics. natural resources forum. wiley online library, pp 137-151. kareem, i.a., adekunle, m.f., adegbite, d.t., soaga, j.a. and kolade, v.o., 2016. economic evaluation of agroforestry practices in ogun state, nigeria. advances in forestry science, 3:3944. kassie, g.w., 2018. agroforestry and farm income diversification: synergy or trade-off? the case of ethiopia. environmental systems research, 6:8. kenya national bureau of statistics., 2010. population census results of kenya by the year 2009. government printers: nairobi, kenya. http://www.afdevinfo.com/htmlreports/org/org_33469. html. kimaro, a.a., sererya, o.g., matata, p., uckert, g., hafner, j., graef, f., sieber, s. and rosenstock, t.s., 2019. understanding the multidimensionality of climate-smartness: examples from agroforestry in tanzania. the climate-smart agriculture papers, springer, pp 153-162. krishnamurthy, l., krishnamurthy, p.k., rajagopal, i. and solares, a.p., 2019. can agroforestry systems thrive in the drylands? characteristics of successful agroforestry systems in the arid and semi-arid regions of latin america. agroforestry systems, 93:503-513. kumar, y. and thakur, t.k., 2017. agroforestry: viable and futuristic option for food security and sustainability in india. international journal of current microbiology and applied sciences, 6:210-222. leakey, r.r., tchoundjeu, z., schreckenberg, k., shackleton, s.e. and shackleton, c.m., 2005. agroforestry tree products (aftps): targeting poverty reduction and enhanced livelihoods. international journal of agricultural sustainability, 3:1-23. mbow, c., van noordwijk, m., luedeling, e., neufeldt, h., minang, p.a. and kowero, g., 2014. agroforestry solutions to address food security and climate change challenges in africa. current opinion in environmental sustainability, 6:61-67. meijer, s.s., catacutan, d., ajayi, o.c., sileshi, g.w. and nieuwenhuis, m., 2015. the role of knowledge, attitudes and perceptions in the uptake of agricultural and agroforestry innovations among smallholder farmers in sub-saharan africa. international journal of agricultural sustainability, 13:40-54. mercer, d.e., li, x., stainback, a. and alavalapati, j., 2017. valuation of agroforestry services. in: schoeneberger, michele m; bentrup, gary; patel-weynand, toral, eds 2017 agroforestry: kinyili et al./ journal of tropical forestry and environment vol. 10, no. 01 (2020) 87-100 99 enhancing resiliency in us agricultural landscapes under changing conditions gen tech report wo-96 washington, dc: us department of agriculture, forest service, 63-72. mosquera-losada, m., santiago-freijanes, j., rois-díaz, m., moreno, g., den herder, m., aldreyvázquez, j., ferreiro-domínguez, n., pantera, a., pisanelli, a. and rigueiro-rodríguez, a., 2018. agroforestry in europe: a land management policy tool to combat climate change. land use policy, 78:603-613. mugenda, o.m. and mugenda, a.g., 2003. research methods. quantitative and qualitative approaches, 46-48. namwata, b., masanyiwa, z. and mzirai, o., 2012. productivity of the agroforestry systems and its contribution to household income among farmers in lushoto district, tanzania. nardi, p.m., 2018. doing survey research: a guide to quantitative methods. routledge. neupane, r.. and thapa, g., 2001. retracted article: impact of agroforestry intervention on farm income under the subsistence farming system of the middle hills, nepal. agroforestry systems, 53:31-37. nzilu, w.b., 2015. farmer's perception and its impacts on adoption of new agroforestry tree (gliricidia sepium) in mwala division, kenya. kenyatta university, paul, c., weber, m. and knoke, t., 2017. agroforestry versus farm mosaic systems–comparing landuse efficiency, economic returns and risks under climate change effects. science of the total environment, 587:22-35. prăvălie, r., 2016. drylands extent and environmental issues. a global approach. earth-science reviews, 161:259-278. prăvălie, r., bandoc, g., patriche, c. and sternberg, t., 2019. recent changes in global drylands: evidences from two major aridity databases. catena, 178:209-231. quandt, a. and mccabe, j.t., 2017. “you can steal livestock but you can’t steal trees.” the livelihood benefits of agroforestry during and after violent conflict. human ecology, 45:463473. quandt, a., neufeldt, h. and mccabe, j.t., 2018. building livelihood resilience: what role does agroforestry play? climate and development, 1-16. quandt, a.k., neufeldt, h. and mccabe, j.t., 2017. the role of agroforestry in building livelihood resilience to floods and drought in semiarid kenya. ecology and society, 22. roshetko, j.m., nugraha, e., tukan, j., manurung, g., fay, c. and van noordwijk, m., 2007. agroforestry for livelihood enhancement and enterprise development. aciar proceedings. aciar; 1998, p 137 scherr, s., 2004. building opportunities for small-farm agroforestry to supply domestic wood markets in developing countries. agroforestry systems, 61:357-370. sharma, n., bohra, b., pragya, n., ciannella, r., dobie, p., lehmann, s., 2016. bioenergy from agroforestry can lead to improved food security, climate change, soil quality, and rural development. food and energy security, 5:165-183. somarriba, e., 1992. revisiting the past: an essay on agroforestry definition. agroforestry systems, 19:233-240. steffan-dewenter, i., kessler, m., barkmann, j., bos, m.m., buchori, d., erasmi, s., faust, h., gerold, g., glenk, k. and gradstein, s.r., 2007. tradeoffs between income, biodiversity, and ecosystem functioning during tropical rainforest conversion and agroforestry intensification. proceedings of the national academy of sciences, 104:4973-4978. syano, n., wasonga, v., nyangito, m., kironchi, g., egeru, a., mganga, k., musimba, n., nyariki, d., nyangito, m. and mwang’omb, a., 2016. ecological and socio-economic evaluation of dryland agroforestry systems in east africa. in: fifth african higher education week and ruforum 100 biennial conference, “linking agricultural universities with civil society, the private sector, governments and other stakeholders in support of agricultural development in africa, cape town”, south africa, 17-21 october 2016. ruforum, pp 525-535. waldron, a., garrity, d., malhi, y., girardin, c., miller, d. and seddon, n., 2017. agroforestry can enhance food security while meeting other sustainable development goals. tropical conservation science, 10:1940082917720667. wulan, y.c., budidarsono, s. and joshi, l., 2008. economic analysis of improved smallholder rubber agroforestry systems in west kalimantan, indonesia-implications for rubber development. sustainable sloping lands and watershed management conference luang prabang, lao pdr. microsoft word 2. fernando *correspondence: preenikmep@yahoo.com tel:+94112758427 issn 2235-9370 print/issn 2235-9362 online © university of sri jayewardenepura 14 geo-informatics techniques for assessing physiological status and productivity of rric 121 genotype of hevea brasiliensis (rubber) under different harvesting systems k.m.e.p. fernando1*, h.m.r. premasiri2, k.v.v.s. kudaligama3 1department of botany, university of sri jayewardenepura, sri lanka 2 department of department of earth resources engineering, university of moratuwa, sri lanka 3department of biochemistry and physiology, rubber research institute of sri lanka date received: 23-11-2016 date accepted: 25-12-2016 abstract rubber (hevea brasiliensis) one of the main plantation crops in sri lanka is the only plant species cultivated commercially for natural rubber harvesting. novel systems for harvesting have been introduced but spatial distribution of photosynthetic potential determining key factor for sustainable cultivation has not been properly explored. use of such techniques such as satellite remote sensing (rs) and geographic information system (gis) to analyse spatial and biological factors related to the productivity of rubber plantation with different harvesting systems is the main objective of the present study. quikebird high resolution satellite images were used for rs analysis. chlorophyll content of rubber leaves was measured using a spad-502 chlorophyll meter. chlorophyll content and satellite images were analysed using gis and spatial statistical methods to determine the variation in different harvesting systems. yield data were collected from the study site and yield parameters were correlated with chlorophyll content and normalized difference vegetation index (ndvi) values. results revealed all systems exhibited promising yield performance without significant deviation but slightly higher yield per hectare per year (yph) and dry rubber content of latex (drc) were recorded in quarter spiral based once in three days (s/3 d4) and weekly (s/2 d1 2d7) harvesting systems. chlorophyll content and rubber yield showed direct correlation in all systems. ndvi vs chlorophyll showed positive correlation r2=0.65 and spatial distribution of chlorophyll and ndvi values demonstrated sound physiological status of plants across the plantation with different harvesting systems. cost effective lih systems showed better production trend demonstrating relatively higher yield while reducing tapping cost and labour. satellite based remote sensing technique is an easy and efficient tool to estimate productivity of rubber plantation over a large area. keywords: chlorophyll, ndvi, harvesting, remote sensing, rubber. 1. introduction rubber (hevea brasiliensis) is the only plant species commercially planted for natural rubber production and being the second largest plantation crop in sri lanka. rubber established as plantation crop in the wet zone and certain region of intermediate zone of sri lanka and is being extended to non-traditional areas especially in moneragala, ampara, vaunia and mulathivu districts. rubber and allied products are one of major export earnings in sri lanka contributes immensely to country’s economy. rubber cultivation aims at latex fernando et al. /journal of tropical forestry and environment vol. 6, no 02 (2016) 14-24 15 yield, and it is a long term investment that has about 30 years of economic lifespan. other than that increasing demand for timber and potential to value of its carbon sequestering capacity through carbon trading are added remarkable benefits. latex harvesting high level of bark consumption is a prime factor for shortening the economic lifespan of the tree. locote et al. (2004) and vijayakumar (2003) reported the application of short cut exploitation system to increase the yield of rubber trees. additionally, shortage of skilled harvesters is another key issue in the rubber industry. labour saving technologies while maintaining the latex yield have been introduced to overcome labour related issues by reducing tapping frequency (sivakumaran et al., 1991; johari et al., 1993; sivakumaran et al., 1993; rodrigo et al., 2004;). reducing the harvesting intensity provides a practical solution to key issues associated with natural rubber industry (rodrigo et al., 2012). low intensity harvesting systems reduce the harvester requirement per plantation and enhance the economic lifespan of rubber trees (nugawela et al., 2000; rodrigo et al., 2004; rodrigo, et al., 2011). different combinations of harvesting frequencies and cut lengths along with different stimulation strategies have been assessed for latex yield and found low intensity harvesting (lih) systems reduced the harvesting cost and increased the profitability of rubber plantations (kudaligama, 2013; kudaligama et al., 2013) spectral analysis of chlorophyll factors that govern and parameters that indicate the efficiency of photosynthetic productivity under field conditions could be used as tools in the selection of hevea genotypes (rodrigo, 2007). nugawela et al. (1995) screened the yield potential of some hevea genotypes using photosynthetic parameters to establish a method for early screening. remote sensing is an effective and efficient technique for updating and analyzing the dynamics of plantations through the multispectral satellite data. chlorophyll concentration is related to the photosynthetic potential and the productivity of the plant and an indirect indicator for physiological status of the plant (danks et al., 1983; gamon and surfus, 1999). several studies on different vegetation types found a correlation between reflectance-based normalized difference vegetation index (ndvi) and chlorophyll content at leaf scale (jones et al., 2007; yoder and pettigrew, 1995) and canopy scale (coops et al., 2003; yoder and waring, 1994). analysing leaf area index of rubber plantation and its dynamics by remote sensing is of great significance in predicting yield and evaluating tapping intensity (chen et al., 2015). multicriteria analysis and data acquisition through satellite remote sensing technology are promising methods to analyse spatial distribution of key factors which govern the yield and productivity in response to different harvesting systems. studies on analysis of latex yield in different harvesting systems in relation to canopy characteristics including photosynthetic potential of rubber have not been carried out in sri lanka. this study aims to apply geo-spatial analysis along with rs techniques to analyse determining factors for physiological status and productivity to make sustainable rubber industry in sri lanka. 16 2. materials and methods 2.1 study area rubber plantations of kuruwita substation of rubber research institute of sri lanka (rrisl) which lies in the wl 1a agro-ecological zone with average annual rainfall about 3200 mm was selected for the study. the study site is located in rathnapura district in sabaragamuwa province in low elevated topographic terrain showing nearly flat ground (figure 1). the experimental field had been replanted in 2002 with rric 121 genotype with paired row system: distance between the pair is 3 m and the distance between two paired rows is 13 m. primary and secondary data were used for the analyses in this research. field and laboratory data such as yield data, in-situ test data, chlorophyll analysis data etc. were obtained as primary data. sampling locations and other ground data were taken using gps coordinates. high resolution remote sensing data; quikebird images were used as secondary data. yield data in four experimental plots practising different harvesting systems (table 1) were obtained during the period from january 2012 to october 2016. figure 1: location map of rubber plantations in kuruwita. fernando et al. /journal of tropical forestry and environment vol. 6, no 02 (2016) 14-24 17 table 1: four latex harvesting systems practising in kuruwita experimental site. harvesting system tapping method and frequency system s/2 d2 half spiral based once in two days frequency traditional harvesting system s/2 d4 half spiral based once in four days frequency low intensity harvesting system (lih) s/4 d3 quarter spiral based once in three days frequency s/2 d1 2d/7 half spiral based two consecutive days per week frequency 2.2 measurement of the yield the amount of latex yield harvested from experimental plots was expressed as follows. daily dry rubber yield per tree (gtt-g) daily dry rubber yield was calculated using the intake per harvester and number of trees tapped. daily dry rubber yield per tree (g)=intake per harvester (g)/number of trees harvested. yield per hectare per year (yph-kg/ha/y) yield per hectare per year was calculated using the average daily dry rubber yield of tree, number of annual tapping days and tree density per hectare. dry rubber content of latex percentage (drc %) latex sample was diluted with two fold of water, mixed well and poured into a cylinder. the reading was taken on the stem of the metrolac immersed in latex. then the percentage of dry matter content was determined using the ready-reckoner chart used in determination of drc% using the metrolac. 2.3 determination of leaf chlorophyll content spad-502 chlorophyll meter was used to measure relative chlorophyll content in rubber leaves non-destructively in the field. randomly selected six trees (average of 24 values per tree) from each plot were measured for chlorophyll measurements. standard method developed by arnon (1949) was used to quantify total chlorophyll content of rubber leaves. locations of the sample trees and boundaries of blocks with different harvesting systems were recorded using hand held gps. 2.4 remote sensing and gis analysis high resolution satellite images were used for this study and image time was selected based on the availability of the images and our sampling time. quikebird world view 2 image was used for this study (date of the image was 02.05.2013). satellite images were processed using basic tools available in arc gis 10.2 software and normalized difference vegetation index (ndvi) was estimated. ndvi is used to estimate the portion of photosynthetically active radiation absorbed by the crop canopy. the prepared 18 ndvi images were classified into 7 classes by re-coding of pixels. this tool is commonly used to indicate the amount of vegetation in an image, and to differentiate vegetated and nonvegetated areas. ndvi was calculated using quikebird satellite images, and the formula for ndvi is given in equation 1. ndvi = (nir – red) / (nir + red) (1) ndvi maps were analysed along with in situ chlorophyll data. all data layers were spatially analysed using spatial analyst and spatial statistical tools. 3. results 3.1 ndvi analysis ndvi map in the area shows some variation in ndvi values from 0.0 to 0.90 within the blocks and experimental plots are completely covered by rubber canopy. however, within the canopy and rows some variation in ndvi values was observed. direction of the row of trees and sun angle affected the ndvi values and remarkable difference in different harvesting systems could not be observed (figure 2). figure 2: ndvi map showing four blocks having different harvesting systems; s/2 d2, s/4 d3, s/2 d4 and s/2 d1 2d/7. chlorophyll content in leaves was slightly higher in trees harvested by low frequency harvesting systems and the highest was recorded in s/2 d1 2d/7 system compared to other systems such as s/2 d2, s/4 d3 and s/2 d4 (figure 4). however, the difference was not fernando et al. /journal of tropical forestry and environment vol. 6, no 02 (2016) 14-24 19 significant between different harvesting systems. the relationship between ndvi values and measured chlorophyll content was linear in rubber leaves at kuruwita site (figure 5). figure 3: spatial distribution of chlorophyll in kuruwita site (interpolation was based on idw method). figure 4: variation in chlorophyll content in rubber leaves of trees subjected to different harvesting systems. s/2 d2 half spiral based once in two days frequency, s/2 d4 half spiral based once in four days frequency, s/4 d3 quarter spiral based once in three days frequency, s/2 d1 2d/7 tapping the tree once in two consecutive days per week. values are means of six replicates. bars represent ±sd. 20 figure 5: correlation between normalized difference vegetation index (ndvi) and total chlorophyll content in rubber leaves at kuruwita experimental site. 3.2 rubber yield analysis yields of traditional harvesting system (s/2 d2) and low frequency harvesting (lih) systems s/4 d3, s/2 d4 and s/2 d1 2d/7 are shown in figures 6, 7 and 8. gtt was greater in all lih systems compared to s/2 d2 system. both s/2 d4 and s/2 d1 2d/7 exhibited the highest gtt over five year period. gtt values between lih systems are not significant but s/2 d4 shows insignificantly lower value (figure 6). figure 6: gtt of four harvesting systems in five year period (2012-2016). gtt (g) (daily dry rubber yield per tree).values are means of five years. bars represent ±sd. fernando et al. /journal of tropical forestry and environment vol. 6, no 02 (2016) 14-24 21 s/4 d3 system showed slightly higher production during the five year period (2012-2016) in terms of yph compared to s/2 d4. however, no significant difference between lih systems and traditional system s/2 d2 was not observed (figure 7). s/2 d2 and s/2 d1 2d/7 systems having same cut length and different frequency of tapping maintained more or less same yields over the years. figure 7: yield per hectare per year (yph) in different harvesting systems in five year period (2012-2016). values are means of five years. bars represent ±sd. dry rubber content of latex did not show significant difference between different harvesting systems though s/4 d2 yielded slightly higher drc%. all systems maintained an average drc above 36% (figure 8). figure 8: dry rubber content of latex (drc %) of different harvesting systems. values are means of five years. bars represent ±sd. 4. discussion with the recent development of space technology, remote sensing (rs) technology has become a potential tool for assessing the economic potential of rubber cultivation. as chlorophyll content of rubber leaves is an indicator of photosynthetic potential and 22 healthiness of a plant, development of an effective and efficient method to assess chlorophyll content of rubber leaves is a vital component of this study. observed variation in chlorophyll content in different blocks was attributed to several factors that affect the chlorophyll content of leaves. sun angle, canopy direction and light intensity are major physical and natural factors that control the chlorophyll content of leaves. ndvi map does not show considerable variation in ndvi values in different blocks, but the variation observed along the rows and canopy is due to combine effect of sun angle and the direction of the rows. ir and red energy absorption and reflection have been studied extensively (gamon and surfus 1999; richardson et al., 2002) and presented indices which are well correlated with chlorophyll content of plant leaves (gitelson et al., 2003). use of satellite images gives advantages as one of the most significant methods for analysing earth coverage data efficiently and effectively. thus, rs techniques can cover large view or area and analyse the data very efficiently. therefore, ndvi analysis which is correlated with in-situ chlorophyll analysis is an effective technique for assessing the productivity of rubber. present study reveals some positive correlation between ndvi and chlorophyll content of leaves. yield performance, in terms of daily dry rubber yield per tree (gtt), dry rubber content of latex (drc %), and yield per hectare per year (yph) over a five year period were evaluated. though gtt was higher in lih systems drc was comparable in all systems. among tested systems s/4 d3 is more productive having more chlorophyll and showing increasing trend in yph. s/4 d3 low intensity harvesting system is more profitable for harvesting rubber latex providing benefits; greater yield and reducing production cost and enhancing commercial life span of the tree. in terms of long term productivity s/4 d3 and s/2 d1 2d/7 are promising harvesting systems over s/2 d2 system in wet zone cultivations. the direct correlation between chlorophyll content and yield was observed in trees grown in the experimental plots. further, ndvi map and chlorophyll distribution map (figures 2 and 3) illustrate the productive indicators i.e higher chlorophyll content in leaves along with ndvi values in s/4 d3 and s/2 d1 2d/7 plots. it is an evident for greater yield performance in the s/4 d3 and s/2 d1 2d/7 plots. lih systems did not show any adverse effects on physiological functions of trees. all systems performed well producing more than 36% drc and comparable yph. the study reveals s/4 d3 and s/2 d1 2d/7 adopted well to the modified harvesting systems producing relatively higher yield while reducing tapping labour requirement which in turn increase the economic return of the plantation. comparable findings were reported by sumehin et al., 2010 working with clone pr 107, the possibility of reducing the need for tappers and high cost of tapping labour by adopting low frequency tapping or short cut length harvesting system while maintaining the a better vegetation. the accessible ndvi value could be used as an indicator for chlorophyll level in a plantation. no significant variation in chlorophyll in different harvesting systems was observed. the canopy photosynthesis of rubber is a determining factor of productivity, and that is naturally optimized by partitioning of photosynthetic capacity carrying by the leaves with respect to natural light exposure (gunasekera et al., 2013). light significantly affects the total chlorophyll content in rubber leaves. the observed variation in leaf chlorophyll content in the plantation indicates the photosynthetic capacity and productivity of trees growing in different sun angles and directions. fernando et al. /journal of tropical forestry and environment vol. 6, no 02 (2016) 14-24 23 5. conclusion spatial analysis of chlorophyll and satellite image data (ndvi) indicate the sound physiological balance of trees and healthiness of the rubber plantation. correlation to chlorophyll to ndvi is more or less same as correlation of leaf chlorophyll content and the latex yield. thus use of satellite based remote sensing technique is an easy and efficient tool to estimate potential rubber production in different harvesting systems in plantations at any scale. acknowledgement we wish to thank university of sri jayewardenepura for granting funds (grant no. asp/06/re/sci/2013/02) and rubber research institute, sri lanka for providing facilities to carry out this research project. every support given by mr. randunu and staff of the department of biochemistry and physiology, rri are also kindly acknowledged. reference arnon, d.i., 1949. copper enzymes in isolated chloroplasts, polyphenoloxidase in beta vulgaris. plant physiology. 24, 1-15. chen, b., wu, z., wang, j., dong, j., guan, l., chen, j., yang, k., xie, g., 2015. spatiotemporal prediction of leaf area index of rubber plantation using ht-1a/1b ccd image and recurrent neural network. isprs journal of photogrammetry and remote sensing. 102, 148-160. coops, n.s., stine, c., culvenor, d. s., chisholm, l.a., merton, r.n., 2003. chlorophyll content in eucalypt vegetation at the leaf and canopy scales as derived from high resolution spectral data. tree physiology. 23, 23-31. danks, s.m., evans,e., wittaker, p.a., 1983. structure, function and assembly. in photosynthetic systems. 15-17. new york, n.y.: wiley. gaman, j.a., surfus, j.s.c., 1999. assessing leaf pigment content and activity with a reflectometer. new phytologist.143, 105-117. gunasekera, h.k.l.k., de costa, w.a.j.m., nugawela, a., 2013. canopy photosynthetic capacity and light response parameters of rubber (hevea brasiliensis) with reference to exploitation. current and agricultural research journal.1 (1), 01-12. johari, h., james, n., sivakumaran, s., yong, h.w., muthu, k. , 1993. productivity and economics of enlarged tasks – a case study. planter’s bulletin, rubber research institute of malaysia. 214, 26-37. jones, c.t., weckler, p.r., maness, n.o., jayasekera, r., stone, m.l., chiz, d., 2007. remote sensing to estimate chlorophyll concentration in spinach using multi-spectral plant reflectance. american society of agricultural and biological engineers. 50 (6), 2267-2273. kudaligama, k.v.v.s., 2013. effectiveness of low intensity tapping suitable for rubber (hevea) grown in the low country wet zone of sri lanka. phd thesis, university of sri jayewardenepura. kudaligama, k.v.v.s., rodrigo, v.h.l., fernando, k.m.e.p., yapa, p.a.j., 2013. response of rric 121 clone to low frequency harvesting systems in the intermediate zone of sri lanka. proceedings of young scientists forum symposium 2012, colombo, sri lanka. 24. 24 lacote r., obouayeba, s., clement-demange, a., dian, k., gnagne, m, gohet, e., 2004. panel management in rubber (hevea brasiliensis) tapping and impact on yield, growth and latex diagnosis. journal of rubber research. 7,199-217. nugawela, a., long, s.p., aluthhewage, r.k., 1995. possible use of certain physiological characteristics of young hevea plants in predicting yield at maturity. journal of natural rubber research.10, 266-275. nugawela, a., peries, m.r.c., wijesekera, s. and samarasekera, r.k., 2000. evaluation of d/3 tapping with stimulation to alleviate problems related to d/2 tapping of hevea. journal of the rubber research institute of sri lanka. 83, 49-61. richardson, a.d., duigan, s.p., berlyn, g.p., 2002. an evaluation of noninvasive methods to estimate foliar chlorophyll content. new phytologist. 153, 185-194. rodrigo, v.h.l. 2007. ecophysiologicl factors underpinning productivity of hevea brasiliensis. brazilian journal of plant physiology. 19(4), 245-255. rodrigo, v.h.l., kudaligama, k.v.v.s., fernando, k.m.e.p., yapa, p.a.j., 2011. harvesting the rubber tree once in four days: a solution to the current issues in the rubber industry in sri lanka. journal of rubber research institute of sri lanka. 91, 15-35. rodrigo, v.h.l., kudaligama, k.v.v.s., fernando, k.m.e.p, yapa, p.a.j., 2012. replacing traditional half cut by a quarter cut with ethephon; a simple approach to solve current issues related to latex harvesting in rubber industry. j. natn. sci. foundation sri lanka .40 (4)283-291. rodrigo, v.h.l., wickramarathna, n.a.a.d., vidanapathirana, r.d., 2004. productivity and tapper shortage in rubber plantations; low frequency tapping can address the shortage of tappers in rubber plantations of sri lanka. proceedings of the first symposium on plantation crop research, colombo, sri lanka. 32-42. sivakumaran, s., ahamad, z., chong, k., 1991. periodic tapping systemsa solution for tapper shortage. planters’ bulletin, rubber research institute of malaysia. 208/209, 111-123. sivakumaran, s., nayagam j., chong, k., yong, h.w., 1993. economics of tapping rubber tree once a week. planters’ bulletin, rubber research institute of malaysia. 214, 1725. sumahin, e.f., obouayeba, s., dick, k.e., dogbo, d.o., anna, a.p. 2014. low intensity tapping systems applied to clone pr 107 of hevea brasiliensis (muell. arg.): results of 21 years of exploitation in south-eastern côte dilvoire. african journal of plant science. 4(5), 145-153. vijayakumar, k.r., 2003.low intensity tapping to reduce cost of natural rubber production. indian rubber journal. 70, 41-42. yoder, b.j., pettigrew -crosby, r.e., 1995. predicting nitrogen and chlorophyll content and concentration from reflectance spectra (400-500 nm) at leaf and canopy scale. remote sensing environment. 53, 199-211. yoder, b.j., waring, r.h. 1994. the normalized difference vegetation index of small douglas-fir canopies with varying chlorophyll concentrations. remote sensing environment. 49, 81-94. jayasiri, purushothaman &vennila/journal of tropical forestry and environment vol. 4, no 01 (2014) 67-79 67 occurrence of polycyclic aromatic hydrocarbons (pahs) in beached plastic pellets from mumbai coast, india h.b. jayasiri 1* , c.s. purushothaman 2 and a. vennila 2 1 national institute of oceanography and marine sciences, national aquatic resources, research and development agency, crow island, colombo 15, sri lanka 2 aquatic environment and health management division, central institute of fisheries education, panch marg, versova, mumbai, 400 061, india date received: 04-10-2013 date accepted: 20-01-2014 abstract pahs are a class of ubiquitous pollutants which consist of two or more fused benzene rings in various arrangements. a number of pah compounds are known carcinogens and bioaccumulate and biomagnify. these compounds originate naturally as well as anthropogenically through oil spills, incineration of waste and combustion of fossil fuels and wood. the environmental consequence of plastic pellets is the sorption of organic pollutants on their surface from the sea surface microlayer (sml) where the hydrophobic contaminants are known to be enriched. the plastic pellets were collected along the recent high tide line from four beaches of mumbai coast bimonthly during may 2011 and march 2012. a total of 72 pools of plastic pellets were extracted, fractionated and analysed by gas chromatograph coupled to a mass spectrometer to evaluate the extent and sources of 16 pahs. the mean σpah concentration in pellets was 9,202.30±114.89 ng g -1 with a wide range (35.4-46,191.58 ng g -1 ). the concentration of fluorene was found to be the highest (1,606.30±251.54 ng g -1 ) followed by anthracene, chrysene and phenanthrene. the σpah concentration was significantly varied among months and there was no significant difference among sites at p=0.05. the 2-3 aromatic ring compounds accounted for 60% of the total pahs in pellets of mumbai coast while 4 rings and 5-6 rings compounds accounted for 26 and 14%, respectively. the ratio of low and high molecular weight pahs indicated that the contamination by petrogenic sources was predominant over the pyrogenic ones in plastic pellets suggesting oil pollution in coastal area of mumbai. keywords: mumbai, pahs, plastic pellets ______________________________________________________________________________ 1. introduction polycyclic aromatic hydrocarbons (pahs) are a class of ubiquitous pollutants that are found in polluted marine areas (karapanagioti et al., 2009) which consist of two or more fused benzene rings in various arrangements (blumer, 1976). there are over 100 different pah * correspondence: hjayasiri@yahoo.com tel: +94 779828173 issn 2235-9370 print/issn 2235-9362 online © university of sri jayewardenepura jayasiri, purushothaman &vennila/journal of tropical forestry and environment vol. 4, no 01 (2014) 67-79 68 compounds (perelo, 2010). a number of pah compounds are known carcinogens (iarc, 1987) and bioaccumulate and biomagnify (who, 2010). these compounds originate naturally as well as anthropogenically through oil spills, incineration of waste and combustion of fossil fuels and wood. this class of organic compounds has been widely studied (neff, 1979; mcelory et al., 1989; tolosa et al., 1996). two types (petrogenic and pyrogenic) of anthropogenic sources of pahs are found. the study of the pahs in coastal marine environments is of great importance as these areas are biologically active and receive considerable pollutant input from land-based sources via coastal discharge. classifying beach litter into groups based on the material each piece is made up of has demonstrated that plastic litter predominates (nakashima et al., 2011). however, once plastic debris reaches the ocean, the floating component is dispersed in various ways and strand on beaches all over the world affecting the marine environment. further, plastic litter is composed of fragments of manufactured plastic products (user plastic) and pre-production plastic pellets (small granules 1-5 mm in diameter) which are raw material used for the production of many different plastic products. the environmental consequence of these organic polymers is sorption of organic pollutants on their surface (mato et al., 2001; endo et al., 2005; karapanagioti & klontza, 2008) from the sea surface microlayer (sml) where the hydrophobic contaminants are known to be enriched (booij & van drooge, 2001; wurl & obbard, 2005) and then their ingestion by marine animals such as sea turtles and birds (laist, 1997; derraik, 2002; mallory et al., 2006). the high affinity of resin pellets with hydrophobic contaminants illustrates their utility as monitoring media for persistent organic pollutants in coastal waters (mato et al., 2001). most of the studies on chemical aspects of plastics have been carried out for organochlorine compounds such as pcbs, hchs and ddts (carpenter et al., 1972; mato et al., 2001; endo et al., 2005; ogata et al., 2009). however, in addition to the chlorinated compounds, some workers evaluated the pahs in plastic pellets and fragments collected from marine environment (rios et al., 2007; teuten et al., 2009; frias et al., 2010; hirai et al., 2011; karapanagioti et al., 2011). fries & zarfl (2012) compared the sorption of several pahs with different polarities to low density polyethylene and high density polyethylene. they found a decrease in diffusion coefficients when the molecular weight of the pahs increases for both the plastic types indicating a hindered diffusion through the matrix as a result of a larger molecule size. karapanagioti et al. (2010) carried out field and laboratory experiments to study the eroded plastic pellets collected from greek beaches as monitoring tools for pahs. two pah distribution indexes -the ratio of lpahs/hpahs (sum of 2and 3-ring pahs to the sum of more than 3-ring pahs)and the ratio of phenanthrene to anthracene (phen/ant) have been used in many studies as useful tools to identify petrogenic and pyrolytic sources of pahs in marine sediments (budzinski et al., 1997; baumard et al., 1998; soclo et al., 2000; de luca et al., 2004). the present study evaluates the extent of contamination and sources of 16 pahs of the priority list of the u.s. environmental protection agency (epa) on beached plastic pellets in mumbai coast. jayasiri, purushothaman &vennila/journal of tropical forestry and environment vol. 4, no 01 (2014) 67-79 69 2. methods and materials 2.1 study area mumbai (18° 55' n, 72° 54' e) is the metropolitan city on the west coast of india and the capital of the state of maharashtra. the state of maharashtra accounts for a 653 km long coastline with 17% sandy beaches, many of them are lying within the mumbai city (kumar et al., 2006). the increase in urbanization and industrialization has led to an increase in marine discharges. the city generates 2.2x10 6 m 3 d -1 of domestic sewage, out of which, about 2x10 6 m 3 d −1 (largely untreated) enters the marine waters including creeks and bays (zingde, 1999). tide, currents and waves bring these pollutants to the beaches. it has a great diversity of industries in the metropolitan region. about 8% of the industries in the country are located upstream around mumbai. a variety of industries, including refineries and petrochemical complexes, from this area release their effluents, largely untreated, into the sea. there are a number of ports wherein the ship and cargo handling activities contribute to marine pollution. this has resulted in the degradation of the coastal water quality, contamination of the adjoining beaches and seafronts (kumar et al., 2006). the tidal range at mumbai coast reaches a maximum value of about 5 m during spring tide (unnikrishnan, 1999). moreover, the seasonally reversing monsoon winds over the northern indian ocean force a seasonally reversing circulation in the upper ocean (shankar et al., 2002). industrial effluents and domestic sewage from the highly developed metropolitan area of the city enter the shelf in the region. during the study, two oil spills were reported off juhu beach in july (stranded mv pavit on juhu beach, 30 th june 2011) and august (sunken mv rak on 4 th august 2011; 24 nautical miles away from the coast). the area has considerable economic importance. out of nine beaches located in mumbai coast, four beaches namely aksa, versova, juhu and mahim, which show wide geographical coverage were selected for the study (fig. 1). mumbai weather experiences very little seasonal variation due to the moderating effect of the arabian sea. however, it can be categorized into four seasons: summer, winter, monsoon and the withdrawal season. december to february is the winter season, march to may is summer, june to september experiences monsoon and october to december is the withdrawal season (http://www.mapsofindia.com/mumbai/mumbai-weather.html). mumbai receives most of the rain during the monsoon season and accounts for a total rainfall of about 1,800 mm in a year. the arabian sea becomes rough and turbulent with high rising waves during the monsoon season. 2.2 sampling the field surveys were carried out on a bimonthly basis from may 2011 to march 2012 to cover all the seasons in aksa, versova, juhu and dadar beaches. the plastic pellets were picked up one by one from the sand surface using solvent-rinsed stainless tweezers or by hand along the high tide line. around 100 pellets were collected from each beach (endo et al., 2005). samples were stored in amber glass vials and transported to the laboratory. pellets were kept in desiccators to remove moisture and stored in pre-baked amber coloured glass vials at 4 0 c till the chemical analysis was performed (hirai et al., 2011). jayasiri, purushothaman &vennila/journal of tropical forestry and environment vol. 4, no 01 (2014) 67-79 70 fig.: 1. map showing the sampling sites in mumbai coast. 2.3 analysis of pahs in plastic pellets the pahs in the plastic samples were extracted and fractionated according to the method described by ogata et al. (2009) for pops in plastic pellets. among the pellets, yellowing ones were selected by the naked eye for chemical analysis. the coloured or pigmented pellets were excluded from the analysis (endo et al., 2005). the pellets were pooled in triplicate with each pool consisting of ten pellets at each site. each pool (sample) was weighed and introduced into a jayasiri, purushothaman &vennila/journal of tropical forestry and environment vol. 4, no 01 (2014) 67-79 71 30-ml amber vial. approximately 15 ml of hexane (chromatography grade, merck) was added and shaken well, and the vial was kept in dark at room temperature for 72 hours for extraction. the extraction was repeated using fresh solvent. these sequential extracts were combined and concentrated by rotary evaporator (superfit, india) up to approximately 0.5 ml and introduced on to a fully activated silica gel column (18 cm x 0.5 cm i.d.; 100-200 mesh silica gel from merck). the column was conditioned using n-hexane. then, the sample extract was added to the column using a combusted disposable pasture pipette and the first and second fractions were eluted with 5 ml and 30 ml hexane respectively. the third fraction, containing pahs, was eluted with 20 ml hexane/dcm (3:1 v/v) and evaporated to ~1.0 ml by rotary evaporator and transferred into 2.0 ml amber vials and further concentrated to 0.5 ml by purified gentle n2 stream, and sealed in an amber vial until analyzed using gas chromatograph (gc). 2.4 gc-ms analysis of pahs the concentrated extract containing pahs was analysed by gc coupled to a mass spectrometer (gc/ms-qp2010; shimadzu, japan), operating in electron impact ionization mode (70 ev). compound separation was achieved using rxi®-5sil ms column of 30 m×0.25 mm i.d. with 0.25 μm film thickness (restek, usa). the temperature programme was as follows: from 100 0 c (holding time 4 min) to 300 0 c at 7.5 0 c min -1 , keeping the final temperature for 15 minutes. injection was in split mode. helium was used as the carrier gas at a flow of 1.5 ml min -1 . the transfer line and the ion source temperatures were set at 280 and 230°c, respectively. the total run time was 45 minutes and the injected volume was 1 µl. the electron impact (ei) mass spectra were acquired in the full-scan mode. the identification and quantification of analytes were carried out with gc/ms solution software (shimadzu, japan) using external standard methods. sixteen pahs considered to be of primary environmental concern according to usepa were analysed in this study. these are naphthalene (naph), acenaphthylene (acy), acenaphthene (ace), fluorene (flu), phenanthrene (phe), anthracene (ant), fluoranthene (flut), pyrene (pyr), benzo(a)anthracene (b[a]a), chrysene (chr), benzo(b)fluoranthene (b[b]f), benzo(k) fluoranthene (b[k]f), benzo(a)pyrene (b[a]p), indeno(1,2,3-cd)pyrene (i[cd]p), dibenzo(a,h) anthracene (d[ah]a) and benzo(g,h,i)perylene (b[ghi]p). pah standard solution (10 ng µl -1 ) in cyclohexane was purchased from sigma-aldrich (germany). 2.5 method validation five samples containing ten pellets each were spiked with deuterated pah surrogate standards of naphthalene-d8, phenanthrene-d10 and p-terphenyl-d14, and analysed to assess the overall procedural recovery; the recovery varied from 84.46% to 87.40%. 2.6 statistical analysis all statistical comparisons were performed using spss software (version 16). analysis of variance was carried out for the effect of month, beach and their interactions at the significance level of p<0.05 for the σpahs, σlpahs and σhpahs. for significant effects, the mean separation was carried out by duncan grouping at p=0.05. cluster analysis was performed for jayasiri, purushothaman &vennila/journal of tropical forestry and environment vol. 4, no 01 (2014) 67-79 72 pah compounds in plastic pellets and sediment to examine the underlying relationships between the compounds. 3. results the mean concentration of sum of 16 pah compounds (σpahs) was extremely high (9202.30±114.89 ng g -1 ) with a wide range (35.4-46191.58 ng g -1 ) in plastic pellets. the concentration of flu was found to be the highest (1606.30±251.54 ng g -1 ) followed by ant, chr and phe in plastic pellets. acy showed the lowest concentration of 49.01±21.21 ng g -1 (n.d.926.03 ng g -1 ). however, phe and ant were found as the most dominant pah with 95.83% detection followed by naph, ace, flu, chr, pyr, flut, b[a]a and d[ah]a with more than 50% frequency of detection. the least detected compounds were acy, b[k]f, b[b]f and d[ah]a (fig. 2). the concentration of 16 individual pahs varied largely among the 72 samples ranging from undetectable levels to 16,936.37 ng g -1 . fig. 2: pahs concentration (mean±se) in plastic pellets (n=72). two-way anova revealed that the temporal variation was significant for σpahs and σlpahs, while spatial variation was significant for σhpahs in plastic pellets. though, there was no spatial variation of σlpahs, the interaction of the months and sites was significant at p=0.05 (table 1). the σpahs accumulation was significantly higher in july and september than that of november, january and march at p=0.05. the σlpah fraction was significantly higher in july and september than those of the other months while that of may was intermediate (fig. 3a). among the sites, significantly higher σlpahs were found in versova (7749.3±2821.82 ng g -1 ) than at the other sites in pellets (fig. 3b). 0 200 400 600 800 1000 1200 1400 1600 1800 2000 n a p h a cy a ce f lu p h e a n t f lu t p y r b [a ]a c h r b [b ]f b [k ]f b [a ]p i[ cd ]p d [a h ]a b [g h i] p p a h s in p e ll e ts ( n g g -1 ) jayasiri, purushothaman &vennila/journal of tropical forestry and environment vol. 4, no 01 (2014) 67-79 73 table 1: results of two-way anova for σpahs, σlpahs and (σhpahs) in plastic pellets (n=72). source plastic pellets df σpahs σlpah σhpahs ms f ms f ms f month beach monthxbeach error 5 3 15 48 48.56x10 7 99.06x10 6 77.84x10 6 58.50x10 6 8.30* 1.69 1.33 27.60x10 7 24.00x10 6 39.27x10 6 16.71x10 6 16.52* 1.48 2.35* 68.48x10 6 11.99x10 7 38.19x10 6 43.92x10 6 1.56 2.73* 0.87 * significantly different (p<0.05) overall mean revealed that lpahs (2-3 ring compounds) were predominant over hpahs in beach plastic pellets of mumbai with 60% of total pahs (fig. 4). the ratio of lpahs to hpahs was calculated bimonthly and which ranged from 1.07 (november) to 6.34 (july) showing the predominance of petrogenic origin pah compounds over pyrogenic ones in plastic pellets. the dendrogram based on cluster analysis also showed the separation of petrogenic compounds and mixed sources of petrogenic and pyrogenic compound in plastic pellets (fig. 5). fig. 3. variation of σpahs (tpahs), σlpahs (tlpahs) and σhpahs (thpahs) a) bimonthly in plastic pellets (the data points with different letters in lowercase and uppercase represent the significant difference for σpahs and σlpahs respectively at p=0.05), (b) beach-wise variation of (bars with different letters represent the significant difference for of σhpahs at p=0.05). fig. 4: overall relative compositions of pahs according to ring number (n=72) in plastic pellets. 2-3 rings 60% 4 rings 26% 5-6 rings 14% jayasiri, purushothaman &vennila/journal of tropical forestry and environment vol. 4, no 01 (2014) 67-79 74 fig. 5. bimonthly variation of during the study in plastic pellets. fig. 6: dendrogram based on complete linkage for pah compound in plastic pellets. 4. discussion marine pollution comprising industrial and domestic loads as well as hydrocarbons and tar deposits leads to the deterioration of most of the beaches and coastal waters around mumbai. the 16 pahs in the priority list of the usepa were evaluated in plastic pellets during the study and the results illustrated substantially higher mean σpah concentration in the pellets of mumbai beaches when compared to the other studies (mato et al., 2001; karapanagioti et al., 2011). the highest range reported is 39-12,000 ng g -1 in los angeles industrial area by rios et al. (2007). jayasiri, purushothaman &vennila/journal of tropical forestry and environment vol. 4, no 01 (2014) 67-79 75 though different authors found different ranges, some have been reported as median and not the mean. the atmospheric transport of pah from heavy urbanization (traffic of trucks and cars) is the most probable pyrogenic source of the pahs (sanderson et al., 2004; cachier et al., 2005). in this study, except acy, other low-molecular weight compounds had high mean concentrations and predominated over the high-molecular weight compounds suggesting that the sources of these compounds are petroleum hydrocarbons in plastic pellets due to oil pollution in the area. the pahs distribution index calculated for plastic pellets also confirmed the oil pollution. in the areas contaminated by petroleum, the sml can be enriched by a factor of 1,000 (hardy et al., 1987) and up to 2,000 (guitart et al., 2008) with hydrocarbons as a result of slick formation. this suggests oil pollution in coastal sea off mumbai. liquid petroleum is a complex mixture of tens of thousands of compounds, in which various hydrocarbons are the most abundant classes, usually accounting for 75% of the total oil composition (ospar, 2004). a typical crude oil may contain 0.2 to 0.7% total pahs, with four to six-ring pahs present at low or trace concentrations (nrc, 2003). during the study, two oil spills were reported in july and august off juhu beach. both the incidents occurred during the monsoon period and the oil might have spread in coastal area by wind-driven surface currents affecting all the studied beaches with different levels of accumulation. further, oil slicks and tar were observed in some pellets on juhu, versova and aska beaches after the oil spills. the risk of major oil spills occurring along the west coast of india is considerably higher now as there has been a significant increase in all types of maritime trade (sivadas et al., 2008). the offshore oil exploration in the bombay high region, mumbai harbour, fishing activities and land-based sources may increase the level of petroleum hydrocarbons in the coastal sea off mumbai. therefore, high concentrations of petrogenic pahs can be expected. the σpahs varied temporally showing significantly high concentration in july and september in pellets and this can be correlated with the two oil spills that occurred in july and august. the low σpahs in january and march indicate that the pellets collected during this period were fresh and there was no impact from oil spills. however, the significantly high concentration of σpahs during july in plastic pellets reveals that plastics have high affinity to sorb pahs than sediment as suggested by teuten et al. (2007). a similar temporal trend was observed for the σlpahs with significantly higher concentration in july and september than the other months which confirms the impact of oil spills on lpahs that sorb to plastic pellets. further, the σhpahs were significantly high in pellets collected from versova beach. dadar and versova are located in a semi-enclosed area geomorphologically with restricted water exchange. thus, the high pah accumulation can be expected in these sites. further, versova had significantly higher organic carbon than other sites (jayasiri, 2013) and receives waste water via malad creek indicating high pollution. mahim bay, where dadar is located, receives large quantities of industrial and domestic waste via mahim creek resulting in high pah pollution. further, sewage from slums and fishing activities also might contribute to the high pah contamination in versova. furthermore, versova fishing boat anchorage and ferry service across the malad creek also could be a significant source for combusted fossil fuel which is a significant source for high-molecular weight pah concentration in pellets from versova beach. moreover, only a few studies relevant to pahs in plastic pellets have been carried out and the jayasiri, purushothaman &vennila/journal of tropical forestry and environment vol. 4, no 01 (2014) 67-79 76 σpahs reported only spatially in the regional scale. the high percentage of plastic pellets has been reported in sediment from versova beach followed by dadar beach (jayasiri, 2013). the compositional patterns of pahs may provide information about petrogenic or pyrogenic sources. pahs may originate from pyrolytic sources including the natural and anthropogenic combustion of organic matter (e.g., forest fires, domestic coal or wood combustion and car exhausts) and from petrogenic sources (e.g., present in subsoil, oil spills) (sun et al., 2008). studies have shown that high σlpahs/σhpahs ratios (>1) often indicate that pahs with petrogenic sources predominate while low ratios (<1) suggest the dominance of pahs of pyrolytic origin (budzinski et al., 1997). phe and ant were found as the most dominant pahs in the present study in pellets showing predominance of petrogenic pahs. hirai et al. (2011) also reported the predominance of petrogenic pahs with a ratio of 0.32±0.49 (hpahs/lpahs) in plastic fragments. while, rios et al. (2007) found a ratio (lpahs/hpahs) of 0.23, indicating that combusted fossil fuels are the principal source of pahs in plastic pellets. crude oil (n=7) has a hpahs/lpahs of 0.19±0.07, whereas wood combustion products and coal combustion products have a hpahs/lpahs of 2.17±1.34 and 6.99±9.92, respectively (saha et al., 2009). beached resin pellets can be used as a tool to monitor pahs in coastal waters. the increasing abundance of plastic debris allows marine organisms to mistake more plastic for their natural food and ingest more plastics as they feed. these plastics are important point-sources carrying pops including pahs (thompson et al., 2009). it is not only the initial organism that ingests the plastics that may be affected by the pops, but also the organisms within its food web. 5. conclusion the sorption of pahs is substantially higher in plastics due to sorbent properties. further, pah in plastic pellets confirmed that the petrogenic sources were predominant over pyrogenic sources indicating oil pollution in the mumbai coastal region. the spatial variation closely related with geomorphology of the area and point sources of domestic and industrial waste water. temporal variation was association with weather pattern especially the monsoon. acknowledgments the first author acknowledges the sri lanka council of agricultural research policy and national aquatic resources research development agency, sri lanka for financial and administrative arrangements to carry out this research at central institute of fisheries education, mumbai, india. director, cife, india is greatly acknowledged for the facilities provided during the study. references baumard, p., budzinski, h., garrigues, p., 1998. polycyclic aromatic hydrocarbons in sediments and mussels of the western mediterranean sea. environmental toxicology & chemistry, 17:765-776. blumer, m., 1976. polycyclic aromatic compounds in nature. scientific american, 234:35-45. jayasiri, purushothaman &vennila/journal of tropical forestry and environment vol. 4, no 01 (2014) 67-79 77 booij, k., van drooge, b.l., 2001. polychlorinated biphenyls and hexachlorobenzene in atmosphere, sea-surface microlayer and water measured with semipermeable membrane devices (spmds). chemosphere, 44:91-98. budzinski, h., jones, i., bellocq, j., pierrad, c., garrigues, p., 1997. evaluation of sediment contamination by polycyclic aromatic hydrocarbons in the gironde estuary. marine chemistry, 58:85-97. cachier, h., aulagnier, f., sarda, r., gautier, f., masclet, p., besombes j.l., et al., 2005. aerosol studies during the escompte experiment: an overview. atmospheric research, 74:547-563. carpenter, e.j., anderson, s.j., harvey, g.r., miklas, h.p., peck, b.b., 1972. polystyrene particles in coastal waters. science, 178:749-750. de luca, g., futonio, a., leardo, r., micera, g., panzanelli, a., piu, p.c., sanna, g., 2004. polycyclic aromatic hydrocarbons assessment in the sediments of the porto torre harbor (northern sardinia, italy). marine chemistry, 86:15-32. derraik, j.g.b., 2002. the pollution of the marine environment by plastic debris: a review. marine pollution bulletin, 44:842-852. endo, s., takizawa, r., okuda, k., takada, h., chiba, k., kanehiro, h., ogid, h., yamashita, r., takeshi, d., 2005. concentration of polychlorinated biphenyls (pcbs) in beached resin pellets: variability among individual particles and regional differences. marine pollution bulletin, 50:1103-1114. frias, j.p.g.l., martins, j., sobral, p., 2011. research in plastic marine debris in mainland portugal. journal of integrated coastal zone management, 11(1):145-148. fries, e, zarfl, c., 2012. sorption of polycyclic aromatic hydrocarbons (pahs) to low and high density polyethylene (pe). environmental science & pollution research international, 19(4):1296-304. guitart, c., frickers, p., horrillo-caraballo, j., law, r.j., readman, j.w., 2008. characterization of sea surface chemical contamination after shipping accidents. environmental science and technology, 42:2275-2282. hirai, h., takada, h., ogata, y., yamashita, r., mizukawa, k., saha, m., kwan, c., moore, c., gray, h., laursen, d., zettler, e.r., farrington, j.w., reddy, c.m., peacock, e.e., ward, m.w., 2011. organic micropollutants in marine plastics debris from the open ocean and remote and urban beaches. marine pollution bulletin, 62(8):1683-1692. hardy, j.t., crecelius, e.a., antrim, l.d., broadhurst, v.l., apts, c.w., gurtisem, j.m., fortman, t.j., 1987. the sea-surface microlayer of puget sound: part ii. concentrations of contaminants and relation to toxicity. marine environment research, 23:251-271. iarc, 1987. iarc monographs on the evaluation of carcinogenic risks to humans, supplement 7, overall evaluations of carcinogenicity: an updating of iarc monographs volumes 1 to 42. iarc, lyon, france. jayasiri, h.b., 2013. assessment of persistent organic pollutants in plastic debris and sediment in mumbai beaches. ph.d. thesis, central institute of fisheries education, mumbai: india. karapanagioti, h.k., siavalas, g., kalaitzidis, s., papatheodorou, g., christanis, k., 2009. distribution of polycyclic aromatic hydrocarbons (pahs) in the gulf of aliveri, central greece, in: proceedings of the 9th national greek symposium on oceanography and fishery: patras, 1. pp.251-255. jayasiri, purushothaman &vennila/journal of tropical forestry and environment vol. 4, no 01 (2014) 67-79 78 karapanagioti, h.k., klontza, i., 2008. testing phenanthrene distribution properties of virgin plastic pellets and plastic eroded pellets found on lesvos island beaches (greece). marine environment research, 65:283-290. karapanagioti, h.k., endo, s., ogata, y., takada, h., 2011. diffuse pollution by persistent organic pollutants as measured in plastic pellets sampled from various beaches in greece. marine pollution bulletin, 62:312-317. karapanagioti, h.k., klontza, i., 2007. investigating the properties of plastic resin pellets found in the coastal areas of lesvos island. global nest journal, 9:71-76. kumar, a., dayal, p., shukla, g., singh, g., joseph, p.e., 2006. ddt and hch residue load in mother's breast milk: a survey of lactating mothers from remote villages in agra region. environment international, 32(2):248-251. laist, d.w., 1987. overview of the biological effects of lost and discarded plastic debris in the marine environment. marine pollution bulletin, 18:319-326. mallory, m.l., robertson g.j., moenting, a., 2006. marine plastic debris in northern fulmars from davis strait, nunavut, canada. marine pollution bulletin, 52:800-815. mato, y., isobe, t., takada, h., kanehiro, h., ohtake, c., kaminuma, t., 2001. plastic resin pellets as a transport medium for toxic chemicals in the marine environment. environmental science & technology, 35:319-324. mcelory, a.e., farrington, j.w., teal, j.m., 1989. bioavailability of polycyclic aromatic hydrocarbons in aquatic environment. in: varanasi, u. (eds), metabolism of polycyclic aromatic hydrocarbons in the aquatic environment. boca raton, fl: crc press, pp. 1–40. nakashima, e., isobe, a., magome, s., kako, s., noriko, d., 2011. using aerial photography and in situ measurements to estimate the quantity of macro-litter on beaches. marine pollution bulletin, 62:762-769. neff, j. m., 1979. polycyclic aromatic hydrocarbons in the aquatic environment: sources, fates and biological effects. barking, uk: applied science publishers. nrc, 2003. committee on oil in the sea: inputs, fates, and effects. national academy of sciences, washington, dc. ogata, y., takada, h., mizukawa, k., hirai, h., iwasa, s., endo, s., et al., 2009. international pellet watch: global monitoring of persistent organic pollutants (pops) in coastal waters. 1. initial phase data on pcbs, ddts and hchs. marine pollution bulletin, 58:1437-1446. ospar, 2004. report of workshop on the evaluation and update of background reference concentrations (b/rcs) and ecotoxicological assessment criteria (eacs) and how these assessment tools should be used in assessing contaminants in water, sediment and biota. hague, netherlands. perelo, l.w., 2010. review: in situ and bioremediation of organic pollutants in aquatic sediments. journal of hazardous materials, 177:81-89. rios, l.m., moore, c., jones, p.r., 2007. persistent organic pollutants carried by synthetic polymers in the ocean environment. marine pollution bulletin, 54:1230-1237. saha, m., togo, a., mizukawa, k., murakami, m., takada, h., zakaria, m.p., et al., 2009.sources of sedimentary pahs in tropical asian waters: differentiation between pyrogenic and petrogenic sources by alkyl homolog abundance. marine pollution bulletin, 58(2):189-200. http://www.sciencedirect.com/science/article/pii/s0025326x08005122 http://www.sciencedirect.com/science/article/pii/s0025326x08005122 http://www.sciencedirect.com/science/article/pii/s0025326x08005122 jayasiri, purushothaman &vennila/journal of tropical forestry and environment vol. 4, no 01 (2014) 67-79 79 sanderson, e.g., raqbi, a., vyskocil, a., farant, j.p., 2004. comparison of particulate polycyclic aromatic hydrocarbon profiles in different regions of canada. atmospheric environment, 38:3417-3429. shankar, d., vinayachandran, p.n., unnikrishnan, a.s., 2002. the monsoon currents in the north indian ocean. progress in oceanography, 52:63-120. sivadas, s., gregory, a., ingole, b., 2008. how vulnerable is the indian coast to oil spills? impact of mv ocean seraya oil spill. current science, 95(4):504-512. soclo, h.h., garrigues, p., ewald, m., 2000. origin of polycyclic aromatic hydrocarbons (pahs) in coastal marine sediments: case studies in cotonou (benin) and aquitaine (france) areas. marine pollution bulletin, 40:387-396. sun, j. -h., wang, g. -l., chai, y., zhang, g., li, j., feng, j., 2008. distribution of polycyclic aromatic hydrocarbons (pahs) in henan reach of the yellow river, middle china. ecotoxicology & environment safety, 72:1614-1624. teuten, e.l., rowland, s.j., galloway, t.s., thompson, r.c., 2007. potential for plastics to transport hydrophobic contaminants. environmental science & technology, 41:77597764. teuten, l., saquing j.m., knappe, d.r.u., barlaz, m.a., jonsson, s., björn, a., et al., 2009. transport and release of chemicals from plastics to the environment and to wildlife. philosophical transactions of the royal society of london, series b, 364:2027-2045. thompson, r.c., swan, s.h., moore, c.j., vom saal, f.s., 2009. our plastic age. philosophical transactions of the royal society of london, series b, 364:1973-1976. tolosa, i., bayona, j.m., albaiges, j., 1995. spatial and temporal distribution, fluxes and budgets of organochlorinated compounds in northwest mediterranean sediments. environmental science & technology, 29:2519-2527. unnikrishnan, a.s., shetye, s.r., michael, g.s., 1999. tidal propagation in the gulf of khambhat, bombay high and surrounding areas. proceedings of indian academy of science, 108(3), 155-177. who, 2010. persistent organic pollutants: impact on child health. switzerland: geneva. wurl, o., obbard, j.p., 2005. chlorinated pesticides and pcbs in the sea-surface microlayer and seawater samples of singapore. marine pollution bulletin, 50:1233-1243. zingde, m. d., 1999. marine pollution: what are we heading for? in: ocean science: trends and future directions. indian national science academy, new delhi, pp. 229-246. popham arboretum: a case study of restoration of slash and burn agricultural lands of sri lanka by low cost silvicultural method madurapperuma et al., /journal of tropical forestry and environment vol. 3, no. 02 (2013) 11-22 11 comparing floristic diversity between a silviculturally managed arboretum and a forest reserve in dambulla, sri lanka b. d. madurapperuma 1* , p. g. oduor 2 , k. a. j. m. kuruppuarachchi 3 , d. n. n. wijayawardene 4 , and j. u. munasinghe 5 1 department of forestry and natural resources, purdue university, west lafayette, in 47906, usa. 2 department of geosciences, north dakota state university, p. o. box 6050, fargo, nd 58108, usa. 3 department of botany, the open university of sri lanka, p.o. box 21, nawala, nugegoda 4 ifs popham arboretum, 2 nd mile post, kandalama road, dambulla, sri lanka. 5 department of zoology, the open university of sri lanka, p.o. box 21, nawala, nugegoda date received: 24-05-2013 date accepted: 09-011-2013 abstract repeated slash and burn cultivation creates wasteland with thorny shrubs, which then takes a long time to become secondary forests through serial stages of succession. assisted natural regeneration through silvicultural management is a useful restoration method to accelerate succession. this survey evaluates the effectiveness of a simple silvicultural method for the rehabilitation of degraded lands to productive forest, thereby increasing floristic wealth. field-based comparative analyses of floristic composition were carried out at a silviculturally managed forest (popham arboretum) and a primary forest (kaludiyapokuna forest reserve) which is located in dambulla in sri lanka. floristic analysis was used to examine the effectiveness of silvicultural techniques for successful restoration of degraded forest in the dry zone. nine 20 m × 20 m plots in each forest were enumerated and the vegetation ≥ 10 cm girth at breast height was quantitatively analyzed. cluster analysis resulted in five distinguishable clusters (two from popham arboretum and three from kaludiyapokuna forest reserve). similarity indices were generated to compare the plots within and between sites. floristic similarity was higher in forest reserve plots compared to arboretum plots. a total of 72 plant species belonging to 60 genera and 26 families were recorded from the study sites. of the recorded species, grewia damine and syzygium cumini (importance value index, ivi = 24 and 23 respectively) were the ecologically co-dominant taxa at the popham arboretum. in contrast, mischodon zeylanicus (ivi = 31), schleichera oleosa (ivi = 25) and diospyros ebenum (ivi = 21) were the abundant taxa in the forest reserve. keywords: dry zone forest, floristics, silviculture, twinspan classification 1. introduction the dry zone of sri lanka covers about four million hectares (60 % of the total island area) and extends over the north, north-central and eastern parts of the island (perera et al., 1977). of the total forest cover in sri lanka (25%), dry zone forest comprises approximately 22% (gunatilleke and gunatilleke, 1983). the dry zone forests of sri lanka have experienced a large-scale depletion of forestland from (a) slash-and-burn (swidden) cultivation (sandika and withana, 2010) and (b) illegal felling or selective logging of valuable timber trees (perera, 2001). natural regeneration of degraded lands is usually poor in * correspondence: bmadurap@purdue.edu tel: +94 112881269; fax: +94112803470 issn 2235-9370 print / issn 2235-9362 online ©2013 university of sri jayewardenepura madurapperuma et al., /journal of tropical forestry and environment vol. 3, no. 02 (2013) 11-22 12 these dry zone forests (weerawardana, 1999) because of the infertile soil and impenetrable barriers of scrub to tree seedlings. repeated slash-and-burn agriculture directly impacts soil fertility that is needed in enhancing re-colonization of indigenous seedlings from a soil seed bank. therefore, restoration of degraded forests using established common methods, including reforestation, is very challenging (weerawardana, 1999). to answer this challenge, artificial regeneration can be initiated. artificial regeneration is a technique of enrichment planting or replanting and is widely practiced in sri lanka albeit with a limited number of available species to convert degraded lands to woodlands. for example, the forest department of sri lanka regularly carries out tree planting campaigns using fast growing exotic trees as gap fillers in forested areas. one of the adverse effects of this kind of strategy is the deliberate introduction of plants that can become invasive species. for instance, leucaena leucocephala was introduced in sri lanka as a multipurpose tree species in the early 1980s to be used as wind buffers for farmsteads, but seedlings have emerged in forests of the southern province and have been prolific (marambe et al., 2001). a simple but effective method to accelerate natural regeneration as an alternative to artificial means was introduced by popham in 1963 (popham, 1993). essentially, this method can be described as a simple low-cost silvicultural method that boosts assisted natural regeneration (anr) in converting deforested lands to more productive forests (dilhan et al., 2010; shono et al., 2007). the guiding principle behind the low-cost silvicultural method was not to plant seedlings of native trees, but to allow seeds of native trees present in the soil seed bank to germinate (popham, 1993). this low-cost silvicultural method is ideal because it is cost effective and easy to implement for private forest landowners to convert their land into a mini-arboretum through forest stewardship programs. this is akin to in-situ conservation of indigenous trees, which ensures the wealth of biological diversity. silvicultural management can be viewed as a disturbance in the ecological sense, except that it is a directed influence with predictable consequences (van miegroet, 1986). for instance, uneven-aged management through mixed-species stands enhances not only structural diversity but also biological diversity (lentz et al., 1989; phillips and abercrombie jr, 1987). changes in structure and function of the forest depend upon the type of silvicultural system employed (boncina, 2000). therefore, the following factors should be addressed before implementing a silvicultural practice: tree composition, patch pattern, growing stock, vertical structure of the vegetation, availability of resources, and species diversity. in this paper, the floristic richness of a managed forest, which depends on endogenous and exogenous influences, including human intervention, was compared to the floristic richness of a forest reserve to evaluate the effectiveness of silvicultural treatments to accelerate serial follow-up stages to bring back the forest. the specific aim of this study was to compare the structure and composition of the vegetation in the two forests using plot sampling. 2. methodology 2.1 study area the main study site for this preliminary survey was the popham arboretum, which has been silviculturally managed for over four decades. the popham arboretum is located in the central province of sri lanka in the matale district. it is about 2.9 km from the kandalama-dambulla road. the total extent of the popham arboretum is 14.4 ha comprising 10.8 ha of woodland and 3.6 ha known as arboretum forest (figure 1). the kaludiyapokuna forest reserve (kfr) was selected for comparison. the reserve is located approximately 6 km from the arboretum and due east of polonnaruwa road and north of kandalama reservoir (figure 1). kfr houses an 8 th – 9 th century monastery complex and caves with prechristian period paintings and inscriptions, and several ponds, and it is protected as a historical site as well as government reserve since 1990 (iucn, 1997). the vegetation at the forest reserve site can be described as a dry mixed evergreen forest characterized by both deciduous and evergreen dry zone plants. madurapperuma et al., /journal of tropical forestry and environment vol. 3, no. 02 (2013) 11-22 13 the annual rainfall is 1,520 mm and the average temperature is 29.5 ° c (cramer, 1993). the major land use types in dambulla study area are scrubland, homestead, forest, and paddy (visvanathan, 2009). the population in dambulla city is 72,082 in 2012 and the population density is 162 persons/km 2 . 2.2 vegetation sampling eighteen random 20 m × 20 m plots were sampled for flora with nine plots in the arboretum and nine plots in the forest reserve. four of the arboretum plots were in an area designated as dry-mixed/evergreen forest, while the rest (5 plots) were selected from the woodland area (figure 1). the dry mixed evergreen forest is dominated by manilkara-chloroxylon series and chloroxylon-vitex-berrya-schleichera series (gaussen et al., 1964). in contrast, plots from the kfr (see also figure 1) were selected by using an altitudinal gradient criterion ranging from a lower valley area to a gentle sloping area. individuals ≥ 10 cm girth at breast height (gbh) (1.3 m above the ground) were enumerated within the plots and were labelled with numbered aluminium tags. vegetation characteristics, which included density and gbh of all woody species, were recorded. the density and basal area of plant species were used to interpret the horizontal distribution of the vegetation. the importance value indices (ivi) of all the species were calculated using relative basal area (rba) and relative density (rd) for individuals (dilhan et al., 2006). ivi is related to rba and rd by the following equation: %ivi = %rba +%rd figure 1: map showing the sampling plots in the popham arboretum and kfr located in dambulla in central province of sri lanka. madurapperuma et al., /journal of tropical forestry and environment vol. 3, no. 02 (2013) 11-22 14 a vegetation classification based on two way indicator species analysis (twinspan) was performed with species abundance data from two sites using pcord4 software (mjm software, gleneden beach, oregon, usa). species composition and community structure between the restored site and the natural forest was compared by computing mean similarity indices using the bray-curtis similarity index (sorensen’s index) with primer © 5 software (magurran, 2004). 3. results and discussion sri lanka ranks second among tropical asian countries in forest degradation, with 40% of forests subjected to degradation (chokkalingam, 2001). most of the dry zone forests in sri lanka are of secondary origin and severely degraded due to shifting cultivation resulting in thorny scrubland (dilhan et al., 2002; perera, 2001; samarasinghe, 1995). however, despite sri lanka’s high ranking and its severe forest degradation, there is very little literature addressing the different types of secondary forests and the characteristics that distinguish a secondary forest from a primary forest (de jong et al., 2001). generally, human induced forest fragments are expected to result in low species richness (mclennan and plumptre, 2012), but it was hypothesized that a silviculturally managed secondary forest harbors more species than forest fragments. therefore, a three-way comparison was constructed; it compared the floristic richness of rehabilitated secondary forest, namely the popham arboretum, to nearby natural forest and with previous floristic studies. 3.1 species richness a total of 72 plant species belonging to 60 genera and 26 families were enumerated for the popham arboretum and kfr (appendix 1). species richness in the arboretum was comprised of 48 plant species, 42 genera, and 21 families, whereas kfr was comprised of 33 plant species, 23 genera, and 16 families. of the recorded species in the arboretum, 35 were trees and 13 were shrubs, whereas at kfr 23 were tree species and 8 were shrub species. two endemic species, diplodiscus verrucosus and xylopia nigricans, were encountered at the arboretum and forest reserve respectively. species richness of the popham arboretum was considerably high; this indicated that the silvicultural management enhanced not only plant diversity but also rehabilitated ambient soils to recolonize juveniles (popham, 1993). when the economic significance of flora was considered, it was found that plants at the arboretum harboured the highest economic value (see appendix 1); 27 had medicinal value, 15 had timber value, and 7 had both timber and medicinal value (cramer, 1993; dilhan et al., 2006). this supported the dilhan et al. (2006) study, which reported 45 plants with medicinal value, 14 with timber value, and 7 with both timber and medicinal value out of 101 species belonging to 91 genera and 42 families at the popham arboretum. these results are also comparable with the floristic study on understory vegetation at the hurulu forest reserve, which documented 49 medicinal plants out of 81 species belonging to 73 genera and 37 families (solangaarachchi and perera, 1993). furthermore, vandercone et al. (2011; 2012) recorded 73 species belonging to 58 genera and 30 families for 59 sampling plots at the kfr. in contrast to the arboretum findings, only 5 medicinal and 3 timber plants were recorded at kfr. this obvious difference between the recorded numbers of arboretum and kfr species may be a sampling issue, because the sample size may not have been sufficient to record all species. 3.2 species and family importance values in the popham arboretum, grewia damine (ivi = 24 / 200) and syzygium cumini (ivi = 23 / 200) were the ecologically co-dominant species. in contrast, the most dominant species in the kfr was mischodon zeylanicus (ivi = 31) followed by schleichera oleosa (ivi = 25) and diospyros ebenum (ivi = 21). the leading family in the arboretum was tiliaceae (ivi = 39 and 2 spp.), whereas euphorbiaceae (ivi = 58, 4 spp.) and sapindaceae (ivi = 45, 4 spp.) were the co-dominant families in the forest reserve. madurapperuma et al., /journal of tropical forestry and environment vol. 3, no. 02 (2013) 11-22 15 species richness in the arboretum ranged from 4 6 for fabaceae, rutaceae and rubiaceae with ivi values ranging from 16 18. however, species richness with four species in the kfr was recorded only in sapindaceae and euphorbiaceae with ivi values ranging from 45 to 58. 3.3 density, basal area, and population size the number of individuals per plot ranged from 36 – 115 at the popham arboretum and from 31 – 108 at the kfr (figure 2). the number of species recorded ranged from 16 – 23 in the arboretum and 9 – 17 in the forest reserve. the arboretum plot a3 had the highest number of individuals (115) with 23 species recorded. in contrast, the arboretum plot a1 had the lowest number of individuals (36) recorded with a comparatively high species richness (figure 2). the average number of individuals in the woodland plots (w1 – w5) was higher (69±11) compared to the arboretum plots a1 – a4 (62±36). at the forest reserve, the average number of individuals was 58±27. the stem density for all woody taxa measured at ≥ 10 cm gbh was 2,433±71 stems per hectare in the arboretum and only 1,442±70 stems per hectare at the forest reserve. the density of individuals was the highest at 0-10 cm dbh size class at both sites (arboretum = 1978±18; kfr = 858±11). the total basal area for the plots sampled at the arboretum was 118±1 m 2 /ha, while it was 505±11 m 2 /ha at the forest reserve. the forest reserve recorded the highest basal area (335±25 m 2 /ha) in the dbh size class greater than 40 cm, whereas the arboretum recorded the highest basal area (44±0.4 m 2 /ha) for 10-20 cm dbh size class. the highest species richness was recorded for the 2-10 population size class for both popham arboretum (18 spp.) and kfr (16 spp.). figure 2. number of individuals per plot sampled at popham arboretum and kfr. the figure represents plots a1 a4 and w1 w5 from the popham arboretum and plots k1 k9 from the kfr. number of species recorded for each plot is displayed above the error bars. the average stem density of plants per plot was high in the silviculturally managed forest compared to the natural forest. the densities of individuals, especially in the lower dbh size classes in the arboretum, were higher compared to the forest reserve since the arboretum was prone to serial slash-andburn cultivation. in contrast, the basal area of plants at kfr was four times larger than at the arboretum due to the increased presence of more mature plants. these results indicated that the arboretum is still in madurapperuma et al., /journal of tropical forestry and environment vol. 3, no. 02 (2013) 11-22 16 the young climax stage with heterogeneous vegetation, which necessitates conservation management and the planning of similar forests. 3.4 trends and relationships the two way indicator species analysis (twinspan) is summarized in figure 3. based on floristic composition, the 18 plots were classified into five clusters. the first division of the classification tree divided into two groups of nine plots with an eigen-value of e = 0.762. the first group comprised of woodland and arboretum plots, showed indicator species of chloroxylon swietenia (buruta) and diospyros habarala (kaluhabarala). the subgroup a2 plot’s indicator species (e = 0.293) was acronychia pedunculata (ankenda). the subgroup a1 (e = 0.274) was characterized by the indicator species, diospyros malabarica (timbiri). four woodland plots (w2 w5) formed the third subgroup. the fourth subgroup consisted of two arboretum plots (a3 and a4) and a single woodland (w1) plot. figure 3: classification (two-way indicator species analysis) of 18 plots sampled in the popham arboretum (arboretum 4 plots labelled a1a4, woodland 5 plots labelled w1 w5) and kfr (plots labelled k1 k9) using species abundance data. the indicator species and the eigen values at each division are also annotated. bold text indicates endemic species. madurapperuma et al., /journal of tropical forestry and environment vol. 3, no. 02 (2013) 11-22 17 the second main group (e = 0.762) also separated into four distinguishable subgroups comprising nine plots located in the kfr. the indicator species, derris scandens (kala-wel), formed the first subgroup (e = 0.363): k8 and k9. for the second subgroup (e = 0.265) only a single plot, k6, could be assigned. the first and second subgroups were classified as upper slope plots. the third subgroup consisted of k2, k3, and k5, which were identified as valley plots. the fourth subgroup was represented by plots k1, k4, k7, and the indicator species, pterospermum suberifolium (welang). these plots were classified as lower slope plots. in the twinspan diagram, the arboretum and the woodland plots were separated as distinct plant communities (figure 3). for example, chloroxylon-grewia-memecylon and diplodiscus-diospyroslepisanthes-sapindus were distinguished as plant communities in the arboretum and woodland, respectively. kfr was associated with the diospyros-xylopiadimorphocalyx-mischodon plant community. species composition of the two sites was not comparable due to the elevation gradient. for example, xylopia nigricans, which was dominant at 225 m elevation in the valley plots of kfr (figure 2), was not recorded in the arboretum. however, mischodon zeylanicus, the dominant species at the lower slope plots of kfr, was found at the rock outcrop of the popham arboretum (cramer, 1993; dilhan et al., 2006; popham, 1993). as shown in the twinspan diagram, the lower slope plots and the valley plots of kfr were closely lumped together at the base of the cluster and shared two dominant species, namely d. ebenum and d. glabellus. in contrast, upper slope plots (k8 and k9) were typically characterized by a liana, derris scandens. as a silvicultural treatment, climbers like these were banned from popham arboretum to assist natural regeneration of native trees (dilhan et al., 2010; popham, 1993). the derived bray-curtis similarity index yielded very high plant abundance similarity estimates for the natural forest (table 1). woodland plots (w1 to w5) also showed relatively high similarity among the plots (with values ranging from 0.33 to 0.70). the arboretum plots had lower similarity indices compared to woodland and natural forest. in addition, the similarity index for arboretum plot a3 was low compared to plots a1, a2, and a4. table 1: comparison of plots within and between sites using the bray-curtis similarity index (sorensen’s index). the bray-curtis similarity index used mean abundance data of species of 18 plots sampled in the popham arboretum (arboretum 4 plots labelled a1a4, woodland 5 plots labelled w1 w5) and kfr (plots labelled k1 k9). madurapperuma et al., /journal of tropical forestry and environment vol. 3, no. 02 (2013) 11-22 18 4. conclusions over-exploitation of dry zone forest through shifting cultivation affects loss of biodiversity in sri lanka. understanding biogeography and floristic wealth of degraded forests is important prior to the introduction of any rehabilitation or restoration program. this survey assesses the implementation of long-term silvicultural management practices and their contribution to floristic wealth. this floristic survey showed that the silviculturally managed forest was equally important to natural forest promising rich biota. therefore, the forest department should apply this silvicultural method to the restoration of degraded shifting cultivation lands in sri lanka to conserve native plants. in addition, the biological wealth of the arboretum makes it advantageous to link it with neighbouring forests like kfr and araula hill through restoration corridors. acknowledgements: the authors extend their gratitude and appreciation to mr. sam popham, mr. j. amarasinghe, curator of popham arboretum, ruk rakaganno current manager of popham arboretum, and the institute of fundamental studies. the authors wish to thank anonymous reviewers for their valuable comments and suggestions to improve the manuscript. references boncina, a. 2000. comparison of structure and biodiversity in the rajhenav virgin forest remnant and managed forest in the dinaric region of slovenia. global ecology and biogeography 9:201-211. chokkalingam, u. 2001. rehabilitation of degraded lands in tropical asia: a synthesis. journal of tropical forest science 13(4):816-831. cramer, l.h. 1993. a forest arboretum in the dry zone. institute of fundamental studies, sri lanka. de jong, w., chokkalingam, u. and smith, j. 2001. tropical secondary forest in asia: introduction and synthesis. journal of tropical forest science 13:563-576. dilhan, m.a.a.b., yakandawala, d., gunatilleke, c.v.s. and bambaradeniya, c.n.b. 2002. structure and composition of a scrubland vegetation in the lower walawe basin irrigation extension area in sri lanka. ceylon journal of science (biological science) 30: 125-145. dilhan, m.a.a.b., weerasinghe, t.d. and amarasinghe, j. 2006. structure and composition of vegetation in the ifs popham arboretum, dambulla. wild lanka 1:90-102. dilhan, m.a.a.b., amarasinghe, j. and wijewardene, d.n.n. 2010. building sustainable botanic gardens: a simple silvicultural method adopted to haven certain wood trees into productive arboretum in the dry zone of sri lanka. proceedings of the fourth global botanic gardens congress bgci, 14.www.bgci.org/files/dublin2010/papers/dilhan-m-a-a-b.pdf access 01 december 2010. gaussen, h., legris, p., viart, m. and labrouse, l. 1964. international map of the vegetation: ceylon (1: 1,000,000). french institute of pondicherry, india. gunatilleke, i.a.u.n. and gunatilleke, c.v.s. 1983. conservation of natural forests in sri lanka. the sri lanka forester 16 (1 & 2): 39-56. iucn [the world conservation union]. 1997. designing an optimum protected areas system for sri lanka's natural forests. iucn/fao1:1-399. lentz, r.j., sims, d.h. and ince, p.j. 1989. are our traditional attitudes restricting forestry management options? in: waldrop, t. a. (ed.) proceedings of pine-hardwood mixtures: a symposium on management and ecology of the type, general technical rep. se-58, u.s.d.a. forest service, southeastern forest experiment station, asheville, nc. pp. 20-24. magurran, a.e. 2004. measuring biological diversity. blackwell publishing: oxford, united kingdom. madurapperuma et al., /journal of tropical forestry and environment vol. 3, no. 02 (2013) 11-22 19 marambe, b., bambaradeniya, c., pushpa kumara, d.k. and pallewatta, n. 2001. human dimensions of invasive alien species in sri lanka. in: mcneely, j.a. (ed.) the great reshuffling human dimensions of invasive alien species, iucn, glard, switzerland and cambridge, uk. pp. 135-142. mclennan, m.r. and plumptre, a.j. 2012. protected apes, unprotected forest: composition, structure and diversity of riverine forest fragments and their conservation value in uganda. tropical conservation science 5:79-103. perera, g.a.d. 2001. the secondary forest situation in sri lanka: a review. journal of tropical forest science 13(4):768-785. perera, w.r.h. 1977. the development of the forest resources of sri lanka. the sri lanka forester 13(1&2): 5-8. phillips, d.r., abercrombie jr., j.a. 1987. pine-hardwood mixtures: a new concept in regeneration. southern journal of applied forestry 11(4): 192-197. popham, f.h. 1993. dambulla. a sanctuary of tropical trees. sam popham foundation, uk. samarasinghe, j. 1995. regeneration dynamics of silviculturally assisted dry zone scrub vegetation at dambulla arboretum. proceedings of the annual forestry symposium, department of forestry and environment science university of sri jayawardanapura, sri lanka, 291-299. sandika, a.l. and withana, n.r.p. 2010. economic analysis of chena cultivation in monaragala district, sri lanka. proceedings of the annual forestry symposium, dept. of forestry and environment science, university of sri jayewardenepura, sri lanka, 15:350-356. shono k., cadaweng, e.a. and durst, p.b. 2007. application of assisted natural regeneration to restore degraded tropical forestlands. restoration ecology 15(4):620-626. solangaarachchi, s.m. and perera, b.m.s. 1993. floristic composition and medicinally important plants in the understory of the tropical dry mixed evergreen forest at the hurulu reserve of sri lanka. journal of national science council sri lanka 21:209-226. vandercone, r. 2011. dietary shifts, niche relationships and interspecific competition in the sympatric grey langur (semnopithecus entellus) and the purple-faced langur (trachypithecus vetulus) in sri lanka. ph.d. dissertation.washington university, st. louis, usa. vandercone, r.p., dinadh, c., wijethunga, g., ranawana, k. and rasmussen, d.t. 2012. dietary diversity and food selection in hanuman langurs (semnopithecus entellus) and purple faced langurs (trachypithecus vetulus) in the kaludiyapokuna forest reserve in the dry zone of sri lanka. international journal of primatology 33:1382-1405. van miegroet, m. 1986. bioecological aspects of silvicultural intervention. forest environment and silviculture 18 th iufro world congress, ljubljan, div. 1(1):273-285. visvanathan, c., setiadi, t., herath, g. and han, s. 2009. eco-industrial clusters in urban-rural fringe areas: a strategic approach for integrated environmental and economic planning. asian institute of technology, 45-69. weerawardana, n.d.r. 1999. natural regeneration of some dry zone forest species assisted by silvicultural management in dry zone woodland at dambulla. the sri lanka forester 23(3 and 4):7-17. madurapperuma et al., /journal of tropical forestry and environment vol. 3, no. 02 (2013) 11-22 20 appendix 1: exhaustive species list of identified vegetation species/family species code local name economic value life form site annonaceae polyalthia coffeoides poco omara t k polyalthia korinti poko ul-kenda m t k * xylopia nigricans xyni heen-kenda t k apocynaceae alstonia scholaris alsc ruk-attana t k * boraginaceae cordia dichotoma codi lolu t a ehretia laevis ehla walangasal m t a capparaceae capparis zeylanica caze sudu-welangiriya m c a/k celastraceae pleurostylia opposita plop panakka t t a clusiaceae mesua ferrea mefe na t k * ebenaceae diospyros ebenum dieb kaluwara t t a/k diospyros habarala diha kaluhabarala t a diospyros malabarica dima timbiri m t a diospyros oppositifolia diop kalu-mediriya t t a diospyros ovalifolia diov kunumella t k * euphorbiaceae bridelia retusa brre kaetakela m/t t a dimorphocalyx glabellus digl welikaha s a/k drypetes sepiaria drse wira t k * flueggea leucopyrus flle heen-katu-pila m s a mischodon zeylanicus mize tammanna t k * phyllanthus indicus phin karaw t a phyllanthus polyphyllus phpo kuratiya s a/k fabaceae bahunia tomentosa bato petan s k * bauhinia racemosa bara maila m t a cassia fistula cafi ehela m/t t a cassia roxburghii caro ratu-wa m t a derris scandens desc kala-wel c k * dichrostachys cinerea dici andara m s a entada pusaetha enpu pus-wael m c k tamarindus indica tain siyambala m/t t a flacourtiaceae flacourtia indica flin katukutundu s a hernandiaceae gyrocarpus americanus gyam diya-labu t k * lauraceae alseodaphne semecarpifolia alse wewarani t t a cryptocarya sp. cryp gal-mora t k madurapperuma et al., /journal of tropical forestry and environment vol. 3, no. 02 (2013) 11-22 21 species/family species code local name economic value life form site loganiaceae abelmoschus angulosus aban kapu-kinissa s k melastomataceae memecylon umbellatum meum kora-kaha m t a meliaceae azadiracta indica azin kohomba m/t t a chukrasia tabularis chta hulunhik m/t t a moraceae ficus amplissima fiam ela-nuga t k * ficus heterophylla fihe wal-ehetu t k streblus asper stas nitul m t a myrtaceae eugenia bracteata eubr daeduwa t a syzygium cumini sycu ma-dan m/t t a ochnaceae ochna obtusata ocob galkera s a rubiaceae benkara malabarica bema getakula s a canthium coromandelicum caco kara m s a canthium dicoccum cadi bokutu m t a catunaregam spinosa casp kukurman m s a ixora pavetta ixpa godaratmal m t a mitragyne parvifolia mipa helamba m/t t a rutaceae acronychia pedunculata acpe ankenda m t a chloroxylon swietenia chsw buruta t t a glycosmis mauritiana glma bol-pana s k * glycosmis pentaphylla glpe dodan-pana m t k limonia acidissima liac divul m t a murraya exotica muex etteriya s k pleiospermium alatum plal tunpat-kurudu m s a sapindaceae allophylus serratus alse kobbe m s a/k dimocarpus longan dilo mora t k * lepisanthes tetraphylla lete dambu t a/k sapindus emarginatus saem penela t a schleichera oleosa scol kon t a/k sapotaceae manilkara hexandra mahe palu t t a sterculiaceae pterospermum suberifolium ptsu welang t a/k sterculia balanghas stba nawa t k tiliaceae berrya cordifolia beco halmilla t t k * diplodiscus verrucosus dive dik-wenna t a grewia damine grda damunu t a/k grewia rothii grro bora-damunu t k * madurapperuma et al., /journal of tropical forestry and environment vol. 3, no. 02 (2013) 11-22 22 species/family species code local name economic value life form site verbenaceae premna tomentosa prto seru t a vitex altissima vial milla t t a/k (economic value: m= medicine, t = timber; life forms: t = tree, s = shrub, c= climber; site: a = arboretum, k= kfr) * species recorded for the arboretum (cramer,1993; dilhan et al., 2006). bold text indicates endemic plants. milkisso/ journal of tropical forestry and environment vol. 10 no. 02 (2020) 39-50 _____________________________________________ *correspondence: kidanepaulos888@gmail.com tel: +25 1911772917 © university of sri jayewardenepura 39 undergraduate university students’ knowledge, attitude and behavior towards biodiversity k.p. milkisso* department of social science and language education, college of education and behavioral studies, addis ababa university, addis ababa, ethiopia date received: 15-01-2020 date accepted: 10-12-2020 abstract the purpose of this study was to assess biodiversity literacy, which includes the dimensions of biodiversity knowledge, attitudes, and behavior among hawassa university undergraduate university students. the descriptive research method was used for the study. results show that a majority of the students were unable to recognize fundamental concepts of biodiversity, which in turn may challenge sustainable biodiversity conservation in ethiopia. in basic biodiversity tests, biology majors scored slightly higher than geography (mean score of 61 to 53 and standard deviation 10.7 to 9.01 respectively). in addition, the findings of the study indicate that there was a weak relationship between students’ level of knowledge and attitudes (r=40) and knowledge and environmental practices (r=24). similarly, a study between attitudes and behaviors at p<0.05, indicated a moderate correlation of r=49. analyses of gender effect reveal that female students’ environmental participatory behavior was higher than their male counterparts were. results further pointed out that students living in the rural area scored significantly higher than the urban counterparts on environmentally responsible action. the mismatch between environmental attitudes and environmentally responsible behaviors suggests, among others, a call for redressing of teaching methodologies that would help students to see their behavior more critically. keywords: biodiversity, biodiversity knowledge, biodiversity attitude, biodiversity behavior, environmental education 1. introduction the most immediate threats to biodiversity have long been habitat loss, due to large-scale conversion of land to agricultural fields and urban centers, the growing number of new urban cores in the periphery area, the introduction of invasive alien species, overexploitation of natural resources, and pollution. climate change is now adding its effects to the cumulative pressures (williamson and bodle, 2016). furthermore, among others, a vital indirect reason for biological diversity loss in many countries is low environmental awareness. biodiversity loss problem awareness mirrors beliefs about to what degree the environment is threatened by anthropogenic activities, and may reflect the environmental problems, such as biodiversity loss (nordlund and garvill, 2002; de groot and steg, 2008). ethiopia is one of the world’s rich biodiversity countries, and it is worthy of attention nationally, regionally and globally. for example, ebi (2014) reported that the country posses around 6,000 species of higher plants, of which 10% are endemic. of fauna resources, 29 wild mammals, 18 birds, ten reptiles, 40 fishes, 25 amphibian and seven anthropoid species are endemic to ethiopia (melaku, 2011). ethiopia is also acknowledged as a center of agro-biodiversity that harbors 172 species in home garden and important gene pools of wild crop relatives for at least 197 species (zemede, 2004). however, according to epa (2012) 40 report about 80,000-200,000 hectares of lands covered with forests are-being cleared per annum in ethiopia for different reasons, resulting in adverse threats to biodiversity. hence, to protect the richness of life forms, it is essential to raise public awareness about biodiversity issues and concerns. mainly teaching the young generation about biodiversity loss has the potential to possess far-reaching profits by empowering them to adopt appropriate conservation and preservation activities, which may be transmitted to their families and communities. regardless of these and other benefits, however, analysis of international studies acknowledged that students lack adequate scientific knowledge about biodiversity. similarly, mnrt (1998) reported that one way of concerning the public at all levels in biodiversity conservation is through environmental education. in addition, unesco and unep (1978) argued that environmental education will enable students to sense out environmental problem and actively participate in pro-environment action. the dynamism of biodiversity has been expressed as complex to conceptualize not few existing studies reported poor public understanding of biodiversity and the risk associated with its loss. hence, inevitably the attainment of biodiversity’s knowledge is often limited by inadequate environmental education and public participation. as stated above, analogous findings were reported by bradley et al. (1999), barrett and kuroda (2002), sivek (2002), christie et al. (2006), fischer and young (2007), lindemann-matthics and bose, (2008), the low level of apprehending of the term ‘biodiversity’ among high school students in swiss, uk, japan, usa, netherlands and scotland. similarly, a study carried out by hunter and brehm (2003) revealed that students of all grade levels experienced little understanding of biodiversity concepts. interestingly, studies on university students’ about the understanding of genetic diversity, species diversity and ecosystem diversity by spash and hanley (1995) revealed that only 44-49% endorsed definitions regarding above mentioned biodiversity components. distressingly, 37% of student participants asserted to be very strange with the definition of biodiversity. in addition, not surprisingly, irez and dogan (2010); found that science teacher trainees exhibited weak biodiversity knowledge. furthermore, the study conducted by makki, abd-el-khalick, and boujaoude (2003) in lebanon and by gambro and switzky (1996) in america indicated that the majority of secondary school students held poor knowledge of the environment particularly biodiversity. nonetheless, the finding of a majority of studies reported more ecologistic and moralistic attitude towards the environment (gambro and switzky, 1999; kuhlemeier et al., 1999; lindemann-matthics and bose, 2008; leather and quicke, 2009; cakir et al., 2010). fischer and young (2007) and buijs et al. (2008) asserted that the empathy of all population structure particularly young adults needs to be appraised because protections of biodiversity are always influenced by citizen knowledge, action skills, and experience. these conceptualized imaginations highly manipulate the mechanisms of conservation strategies. thus, increasing biodiversity loss and the above findings highlight the significance of more study about students’ knowledge, concern and behavior about biodiversity to inform future policy decisions. as stated by macdougall, mccann, gellner, and tur (2013); loss of biodiversity impedes the capability of an ecosystem that is needed for human survival by worsening climate change adaptation and mitigation more likely in developing countries. from this context, the understanding of biodiversity by young adults in agrarian countries such as ethiopia is most crucial and worth exploring. among this group, higher institutions students are chiefly important, as future policymakers and leaders will most likely be found among them. hence, to explore what university students understand about biodiversity; this study assesses a sample of students at hawassa university, located in southern nations, nationalities and peoples region. hawassa university has been purposively selected as the study site due to its long history in agriculture fields. furthermore, young peoples’ environmental knowledge, attitudes, and practices are essential as they ultimately play a crucial role in providing knowledge–based solutions to new and unforeseen environmental problems. milkisso/ journal of tropical forestry and environment vol. 10 no. 02 (2020) 39-50 41 1.1 statement of the problem biodiversity provides community just not only material welfare and livelihoods but contributes to resiliency, security, social relations, health, and freedom of choices and actions. difalco and chavas (2009) found that maintaining agricultural biodiversity in the field, allow farmers to increase productivity and mitigate the negative effects of climate change. this seems to indicate that in countries like ethiopia enhancing agricultural biodiversity is critically important to achieve food security and diminish the chronic dependence on external food aid. however, human actions are fundamentally, and to a significant extent irreversibly, changing the diversity of life on earth, and most of these changes represent a loss of biodiversity. to be aware of the impacts of these substantial interventions and to manage their impacts wisely, we need to address critical gaps in our knowledge about biodiversity. this includes understanding the drivers of biodiversity change (including processes of biodiversity generation and loss), as well as the interactions between species, genetic and ecosystem diversity. according to roth (1992) and wilke (1995), developing a theoretical or practical understanding of the environment is equivalent to developing responsible environmental behavior, and individuals’ behaviors reflect the level of their environmental literacy. similarly, hines, hungerford, and tomera (1987); unesco and unep (1978) argued that the cognitive strand—environmental knowledge comprises comprehending of the ecological processes basic to understand how humans affect natural ecosystems, and strategies of environmental action, including the ability to identify and critically evaluate alternatives for mitigation. furthermore, it was also argued by hsu (2004) and mcmillan et al. (2004) that rising citizen’s environmental knowledge through environmental education results in more positive attitudes towards the environment and more responsible environmental behavior. however, as stated by hungerford and volk (1990), in spite of that knowledge it is a crucial component of environmental literacy, but it alone is not an adequate herald for environmentally responsible behavior. thus, it is essential to empower people with a belief in their ability to contribute to environmental solutions through personal behavior. it has been found by olympia and alexandros (2012) that despite positive attitudes possessed towards biodiversity students were not so devoted in taking action to improve the environment. we need to educate people on what is happening and what we stand to lose, and how rapidly we may lose it if remedial actions are not taken soon. if appropriate knowledge, attitude and willingness to take action to solve the environmental problems are nurtured in learners, they can provide knowledge-based solutions for the prevailing environmental degradation in general and biodiversity loss in particular. furthermore, as leaders of environmental education in school, these prospective teachers need to believe in their capability to promote environmental change so they can foster that belief in their students. hence, to achieve in halting the environmental problems in ethiopia through changing young generation attitudes, developing their knowledge of environment, and raising their participation at every level of education it is prudent to explore pre-service teachers’ awareness, knowledge, attitude, behavior, and intention about the environment. this study, therefore, was designed to fill this gap, since education is the most powerful weapon to comprehend the complex nature of environmental degradation and the way how to rehabilitate it. moreover, to date, to the best of the researcher’s knowledge, there are no published similar studies that were found in ethiopia that dealt with students’ knowledge, attitude and participatory behavior towards the loss of biodiversity, at any level, let alone with university students. it is believed that this research will inspire more works of this kind in developing countries and elsewhere in the future. 1.2 research questions in order to address the research gaps, the study sought to provide answers to the following research questions.  what is the level of students’ biodiversity knowledge? 42  what is the attitude of students toward biodiversity?  what is the degree of students’ biodiversity responsible behavior?  are there statistically significant differences among students’ gender, academic stream and the residential area towards curbing the loss of biodiversity? 1.3 significance of the study for all level curricula designers, course developers, and policy makers, the study can contribute to demonstrate the literacy level of undergraduate students about the loss of biological diversity, which may help to fill the gap, if any, in the policy in general and curricula materials in particular. in addition, it might give information that initiates other researchers to investigate comprehensively on the problem. furthermore, this study is important in that it can contribute a valuable source of information that may be considered by any environmental protection organizations which aim to have an interest in making learning institutions more productive to address such environmental problems. 1.4 limitation the study may lack external validity due to the relatively small sample size, which in return impede random statistical sampling procedures. in addition, one concern about this study is its choice of preselected answers for students to choose from and the very short time allotted to students to answer the inventory, which makes it very difficult to draw any meaningful implications. moreover, the shortcoming of this study is in its sole reliance on quantitative methods of data collection and analyses. furthermore, in the course of the study, the researcher had encountered a lack of published research outputs in the country that focused on and discussed the related study problem. 2. methods and materials 2.1 method, population, sample and sampling techniques the study employed a descriptive research design. hawassa university was randomly selected among the public universities because all the public universities of the country are using the nationally harmonized curriculum. all the public universities are financing by the government, and they are almost similarin resources and facilities. hence, the selection of one public university can possibly represent the rest. as the research focuses on biodiversity, the academic units that offer the programs related to biodiversity were purposively selected. accordingly, all first-year undergraduate students in geography and biology were chosen as the participants of the study using censu method. the participants’ age range from 19 to 21 and all coming straight from high school. the participants of the study were seventy-nine 1st year undergraduate students, 21 females and 58 males majoring biology and geography. they were targated of the study for four reasons. firstly, they are studying environment-affiliated fields. secondly, the newly revised geography and biology syllabi and the textbooks comprise relatively sufficient opportunities to address environmental issues in general and issues related to biodiversity in particular. thirdly, to examine the effect of attained high school environmental education lessons on their conceptual knowledge. fourthly, they are the only prospective teachers who are assigned to teach the environmental subject in secondary schools. 2.2 data collection and analysis in this study, textbooks and undergraduate modules analysis, multiple-choice knowledge tests, and attitude and performance likert scale items were used as the main data-gathering instrument. to develop the items, the researcher assessed the current grade 9-12 geography and biology textbooks through content analysis with educational experts and biology and geography teachers as panels of an expert. this was because, in ethiopia, environmental education is not a stand-alone subject but concepts related to milkisso/ journal of tropical forestry and environment vol. 10 no. 02 (2020) 39-50 43 environmental issues are mentioned in different subjects (by using a multidisciplinary approach), mainly in environment-affiliated subjects such as geography and biology. the environmental knowledge test consisted of 25 multiple-choice items divided into five themes: (a) fundamental principles of ecology) (5 questions) (b) global environmental issues (5 questions) (c) local environmental issues focused on the basic components of an ecosystem (5 questions) (d) ecological values of biodiversity (5 questions) (e) strategies for biodiversity conservation (5 questions). the environmental attitude questions include items compatible with the nep (new environmental paradigm) scale adopted from dunlap; van liere; mertig and jones, 2000, that is-contextualized in the ethiopian environments as well as to the reality of student life and context. they comprise 20 items evaluating students’ perception using a 5-point, likert-type scale. the categories were: (a) the use of environmental legislation as a tool for environmental management (b) the value of the natural environment (c) human–environment interrelationship (d) priorities for national resource management policy and (e) the importance of environmental education. the environmental behavior assessed by asking students to state the extent to which they carried out 15 environment-related activities using a 5-point; likert-type scale ranging from 1 (never) to 5 (almost always). after compiling the questionnaire, pilot study was conducted, on 79 first year geography and biology students in addis ababa university from these results; perfections were made so that the final questionnaire supplied only relevant and informed data. in addition, the questionnaire was examined by three experts in the field of environmental education and modified according to their suggestions for improvement. cronbach’s coefficient of the questionnaire was calculated for the sample respectively 0.69 for environmental knowledge, 0.61 for environmental attitudes and 0.58 for environmental behavior, which indicates good internal consistency of the items. (a) knowledge inventory multiple-choice knowledge inventory questions that consist of 25 items were developed in which the correct responses have weighted a score of one and incorrect responses as a score of zero. the lowest possible total score is zero, and the highest total score is 25 (25×1) which was converted into 100% for the sake of valuation convenience. (b) attitude inventory the attitude inventory consists of 20 questions rated on a likert-type of scale that ranges from strongly agree to strongly disagree with measuring the extent to which the students’ environmental concerns were favorable or unfavorable with respect to biodiversity conservation and towards taking environmental action. in assigning values to favorable items, the scale was weighted going from strongly agree, agree, undecided, disagree, strongly disagree, having 5, 4, 3, 2, 1 values, respectively. but, in the case of unfavorable items these values were reversed in the scale strongly disagree, disagree, undecided, agree, strongly agree, having 5, 4,3,2,1 values respectively. the items were worded both positively and negatively to reduce the risk of obtaining false responses. a neutral score occurred if students answered primarily in the midrange of 3.0. thus, a score of 60 (3×20) had taken as a neutral position. (c) participatory behavior inventory to weight up students’ participatory behavior for the sustainable environment 15 statements were written on a five-point likert scale. in this scale, zero was assigned for response never; 1 to rarely, 2 to sometimes, 3 to often and 4 to always based on students’ responses to each item. hence, the highest score would be 60 (15×4) shows, the best performance of students in practical environmental actions, while the 44 lowest possible score zero indicates environmentally irresponsible behavior. the responses ‘’often’’ and ‘’always’’ were considered as acceptable whereas ‘’never’’ and ‘’rarely’’ response considered as unacceptable participatory actions. since environmental knowledge and attitude assessed out of 100, for the sake of simplicity in correlation, the environmental practice score also converted to 100. the data collected from respondents were analyzed using inferential statistics like independent sample t-test and descriptive statistics such as percentages, frequency distributions, mean scores and standard deviations. in addition, a pearson correlation was employed to determine relationships between respondents’ environmental knowledge, attitude and participatory behavior. 3. result and discussion 3.1 the effect of gender on the conceptual knowledge an analysis of gender effect was not a key to this study. this variable was included in the intention to enrich the findings of the study. as shown in table 1, female geography and biology students scored significantly higher (m=49.80, sd=10.08) than their male counterparts (m=45.18, sd=8.98) on biodiversity conceptual knowledge; md=9.02, t (77) 3.50, p=0.001, α=0.05. these results suggest that; sex affects the level of students’ environmental conceptual knowledge. this finding is supported by findings of tuncer et al. (2005), alp et al. (2006), and fatih and osman (2010) who came up with the result that shows female students are keener to environmental issues than male students. the probable reasons for this result are female students’ active participation in school environmental clubs, work as a member of the association of environmental and outdoor education and volunteer in tree planting campaigns. however, this finding contradicts the conclusions of gifford et al. (1983), gambro and switzky (1999) and groves and pugh (1999) who reported that male students scored significantly better than female students did. this gender related differences could be a fertile area of future study, including the impact of student and school attributes on environmental knowledge of students. table 1: analyses of gender effect on the conceptual knowledge of biodiversity. gender n mean std. deviation df t sig (2-tailed) mean difference male 58 45.18 8.98 female 21 49.80 10.08 77 1.334 0.186 4.62 3.2 analysis of place of residence effect on the biodiversity conservation practice as shown in table 2, students living in rural area scored significantly higher (m=54.64, sd=13.94) than their urban counterparts (m=47.19, sd=16.38) on biodiversity conservation behavior; md=6.95, df (77) t=2.01, p=0.001, α=0.05. these results suggest that the place of residence has an effect on the act of students’ biodiversity conservation participatory behavior because environmental concern and practice were much stronger in degraded landscape rural areas than in urban. this is also probably due to many reasons like parents’ influences, continuing deforestation, habitat loss, water resource depletion, etc. this trend is mirrored in research that suggests outdoor experiences and interaction with natural environment can be mostly effective in closing gaps in pro-environmental behavior associated with place of residence (cheng and monroe, 2010). table 2: mean and standard deviation of place of residence effect on the biodiversity conservation behavior. place of residence n mean std. deviation df t sig (2-tailed) mean difference urban 41 47.19 16.38 rural 38 54.64 13.94 77 2.01 0.047 6.95 milkisso/ journal of tropical forestry and environment vol. 10 no. 02 (2020) 39-50 45 3.3 level of students’ biodiversity conservation knowledge, attitude and participatory behavior based on academic stream. (a) biodiversity knowledge the data in table 3 reveal that biology students demonstrated a higher level of biodiversity knowledge in comparison with geography students. table 3: students’ mean scores for biodiversity knowledge, attitude and practices. department n variables mean above mean below mean std. deviation n % n % geography 36 knowledge 53 19 53 17 47 9.010 attitude 74 28 78 8 22 7.894 practice 56 26 71 10 29 9.355 biology 43 knowledge 61 25 58 18 42 10.70 attitude 76 36 84 7 16 8.207 practice 59 31 72 12 28 10.073 the majority of biology students (61%) and more than half of geography students (53%) score above average which shows their biodiversity knowledge is medium and not encouraging. even though more than half of students scored above average, the majority of students appear to have very general, fragmentary and uncritical knowledge about biodiversity. students lacked fundamental ecological knowledge on items, such as ecological, economic and social value of biodiversity; major endemic plants of ethiopia; intrinsic, existence and bequest value of biodiversity; direct and indirect causes of biodiversity loss in ethiopia; impacts of biodiversity loss on perpetuation of human beings and main steps to successful biodiversity conservation. for example, regarding ecological value of biodiversity disappointingly only very few geography (13%) and biology (16%) students could give correct responses. similarly, a large percentage of biology (70%) and geography (88%) students answered incorrectly about the crosscutting causes of biodiversity loss in ethiopia. distressingly, a considerable number of the biology (75%) and geography (86%) students did not recognize critically endangered mammal species in ethiopia, a basic knowledge expected from graduates of secondary school. the conservation of endangered species seems to be least important to them. the probable reason for inadequate biological diversity knowledge might be because of listed teaching methods such as field trip, laboratory work, outdoor activities, discussion, etc. to teach environmental issues were not practically exercised by the instructors due to many constraints like time, budget and large classes size. additionally, these findings suggest that environmental education teachers must be increasingly encouraged and supported through on-the-job training or curriculum development. this finding is supported by the conclusion of gambro and switzky (1996), hunter and brehm (2003), makki, et al. (2003), lindemann-matthics and bose (2008), and irez and dogan (2010) who came up with results that reveal secondary school and undergraduate university students held insufficient environmental knowledge but promising pro-environmental attitudes. furthermore, the existence of the knowledge gap between students of biology and geography streams was observed clearly. this significant mean difference between two streams might be because of the fact in which the environmental issues more or less better integrated in biology curriculum than in geography curricula and syllabi. (b) biodiversity attitude according to the attitude test score of the students (see table 3), nearly more than half of biology students (84%) and geography students (78%) score above average (m=76 and 74), which shows their attitude is moderate. one can hence conclude that most of the students have a positive attitude towards 46 biodiversity conservation. the probable reason is that the attitudes of ethiopian society toward environmental issues are changing. issues pertaining to environmental rehabilitation are continuously gaining status in the national agenda such as reforestation and afforestation companies named ‘’green legacy’’ and receiving more media exposure. hence, the public may be more realized that biodiversity is deteriorating. the integration of environmental issues in to school curriculum and syllabus may also contribute to increase awareness of the environmental crisis. similarly, a study conducted by kuhlemeier, bergh et al. (1999), aini et al. (2003), dimopoulos and pantis (2003), and makki et al. (2003) revealed that the elementary school, high school, college and university students possessing favorable attitudes towards the environment, regardless of their low level of environmental knowledge. (c) biodiversity conservation behavior with regard to biodiversity conservation practice, as shown in table 3, students’ environment friendly participatory practice mean score was 56 for geography students and 59 for biology students with a large standard deviation. this result indicated that more than half of students’ accepted that their role in biodiversity conservation is essential and they are ready to be involved in conservation effects. popular environmental actions include having colossal interest to study issues related to biodiversity loss (88% biology and 96% geography), planting indigenous and wildlife-friendly trees (86% biology and 77% geography), participating in environmental protection club (93% biology and 92% geography), establishment of laws policies and orders for biodiversity conservation (73% biology and 82% geography). nonetheless, only 35% of geography and 42% of biology students acknowledged that they had taken deliberate action to diminish biodiversity loss. as future teachers, they are pledged to actively teach students the concept of biodiversity, the importance of biological diversity and various methods used for sustainable conservation. however, a considerable number of participants unfortunately in this study did not show positive inclination and commitment towards pro-environmental behavior. among others, the probable reasons for this result are a lack of activities in environmental clubs, parents’ low socio-economic and educational background, lack of environmental education field trip, and the unpopular and forced government-imposed environment rehabilitation campaign. one concern of this study is that despite the evidence exhibited regarding environmental practice, it was not identified which factor appears to be stronger in motivating students to take responsible environmental action. skelly and zajicek (1998), and cheng and monroe (2010); found that time in natural area was a key predictor of pro-environmental behavior. similarly, hines et al. (1987) in their study argued that knowledge alongside pro-environmental attitudes are requisites to environmentally responsible behavior. 3.4 relationship of biodiversity knowledge, attitude and behavior correlation analysis results in table 4, revealed that there were low to moderate, positive correlation among biodiversity knowledge, biodiversity attitude, and biodiversity conservation behavior. table 4: pearson’s correlations among biodiversity knowledge, attitude and participatory behavior. correlations are significant at the 0.01 level as can be seen, the correlations showed a weak relationship between knowledge and attitude (r=0.398). the probable reason for this discrepancy may be due to that the students, regardless of their pro-environmental attitudes do not fully understand the fundamental ecological principles related to biodiversity issues. an alternative elucidation for an insignificant relationship between knowledge and variables attitude behavior knowledge 0.398 0.243 attitude 0.491 milkisso/ journal of tropical forestry and environment vol. 10 no. 02 (2020) 39-50 47 attitude may be expressed attitudes reflecting not factual value but the influence of mass media and community interest. moreover, the attitudes demonstrated by the students in this study may mirror their desire to identify with what they instinctively accept as the right value. to this end, the relatively low correlation that was found between students’ knowledge and attitude may maintain the idea that environmental knowledge does not appear to be a prerequisite for an ecocentric attitude. this is consistent with the findings of kuhlemeier et al. (1999), aini et al. (2003), and dimopoulos and pantis (2003) who reported that inadequate environmental knowledge parallels alongside with positive attitudes. the relationship between knowledge and behavior had an overall weak correlation (r=0.243). this finding is substantiated by kuhlemeier et al. (1999) who found a weak correlation (r=0.020) between knowledge and behavior in the study made on youth environmental knowledge, attitudes and responsible behavior. hines et al. (1987) made a study to determine the relationship of knowledge and behavior and found an overall correlation of r=0.299 from the 17 studies that reported this data. according to kaiser, wolfing and fuhrer (1999 p.4) ‘’factual knowledge should not be related to ecological behavior strongly because its influence is attenuated both by environmental attitude and intention’’. these studies contradict hines et al. (1987) and ajzen et al. (1988) who argued that knowledge is a prerequisite for environment friendly behavior. analysis between attitude and behavior at p<0.05, indicated a moderate correlation of r=0.491. this finding is supported by hines et al. (1987), and kuhlemeier et al. (1999) who found a moderate correlation of r=0.347 and r=0.36. hines et al. (1987) finds a counter-intuitive result that when the behavior was actually observed rather than self-reported, the attitude-behavior correlation went up to r=0.427. the results of their study may have been enhanced because self-reported behavior is usually over-reported. on the contrary, in the scott and willits (1994) study of pennsylvanians’ environmental attitudes and behaviors, they found that attitudes were predictive of behaviors but a weak correlation (r=0.21). in general, results revealed that there is a weak correlation between knowledge and behavior, and moderate correlations between attitudes and knowledge and between attitudes and behavior. 4. conclusion and implications biological diversity is a vital resource as it supplies both services and goods to the community. however, in recent years, anthropogenic activities have happened to be the most dominant and persistent driving forces in biodiversity loss. in order to reduce the threats that biodiversity is facing due to human activities globally, regionally and locally, the public must have basic knowledge and demonstrate a positive attitude and behavior towards biodiversity and its worth. nevertheless, the overall findings presented in this study are either not encouraging or very disappointing. in addition, in ethiopia, a long phase of the exponential growth of population and poverty exacerbates the problem. these two reasons plus a limited understanding of how biodiversity regulates ecosystem functioning at a local and global scale have combined to exert enormous pressure on the natural habitats and native plants and animals. consequently, ethiopia faces substantial challenges concerning sustainable development, making environmental education particularly critical as a tool for attaining sustainable development. inculcating environmental literacy in future generations requires educators who are equipped with knowledge, skills, attitude, and commitment. the ethiopian education policy recognizes that environmental education is important for a scientifically literate citizenry. however, the environmental issues incorporated in the secondary school texts were insufficient for influencing students’ environmental knowledge, attitudes, and behaviors, as environmental problems in the country are very complicated. for these reasons, environmental education programs should be revised in detail, and the contents of the courses and classroom instructional approach should be revisited at high schools, universities, and teacher education programs. in particular, since future teachers are shapers and educators of the future generation, designed and implemented curricula must foster a coherent understanding of the fundamental 48 principles of the environmental. it might be also useful to link the conceptual problems to hands-on experiences when possible that could easily be illustrated through a field trip, students experiment, and teacher demonstrations. moreover, teacher candidates who graduated from universities and colleges should be granted service training to dispel mismatch between environmental knowledge and environmental behaviors. future study requires to assess appropriate teaching methods which best promote firm comprehension of these complex environmental issues. furthermore, the actual causes of the discrepancy in the three variables namely environmental knowledge, environmental attitudes, and environmental behaviors should be further investigated to make a sound conclusion. competing interests authors have declared that no competing interests exist. references aini, m., fakhru’l-razi, a., laily, h. and jariah, m., 2003. environmental concerns, knowledge and practices gap among malaysian teachers. journal of sustainability in higher education, 4:305313. ajzen, i., 1988. attitudes, personality, and behavior. chicago, il: the dorsey press. alp, e., ertepinar, h., tekkaya, c. and yilmaz, a., 2006. a statistical analysis of children’s environmental knowledge and attitudes in turkey. international research in geographical and environmental education, 3:210-223. barrett, b. and kuroda, a., 2002. ecological modernization, environmental knowledge and societal change: attitude and behavior of young people in japan. international research in geographical and environmental education, 11:237-261. bradley, j., waliczek, t. and zajicek, j., 1999. relationship between environmental knowledge and environmental attitude of high school students. journal of environmental education, 3:17-21. buijs, a., fischer, a., rink, d. and young, j., 2008. looking beyond superficial knowledge gaps: understanding public representations of biodiversity. international journal of biodiversity science and management, 4:65-80. cakir, m., irez, s. and dogan, o., 2010. understandings of current environmental sigues: turkish case study in six teacher education colleges. educational studies, 36:21-33. cheng, j. and monroe, m., 2010. connection to nature: children’s affective attitude toward nature. environmental behavior, 44:31-49. christie, m., hanley, n., warren, j., murphy, k., wright, r. and hyde, t., 2006. valuing the diversity of biodiversity. ecological economics, 58:304-317. de groot, j. and steg, l., 2008. value orientations to explain beliefs related to environmental significant behavior. how to measure egoistic, altruistic, and biospheric value orientations. environmental behavior, 40:330-354. di falco, s. and chavas, j., 2009. on crop biodiversity, risk exposure and food security in the highlands of ethiopia. american journal of agricultural economics, 91:147-156. dimopoulos, d. and pantis, j., 2003. knowledge and attitudes regarding sea turtles in elementary students on zakynthos, greece. the journal of environmental education, 34:30-38. dunlap, e., van liere, d., mertig, angela g. and jones, r., 2000. measuring endorsement of the new ecological paradigm: a revised nep scale. journal of social issues, 56:425-442. ethiopian biodiversity institute (ebi), 2014. ethiopia’s fifth national report to the convention on biological diversity, addis ababa, ethiopia. environmental protection authority (epa), 2012. environmental education guidelines to ethiopia. addis ababa: epa. milkisso/ journal of tropical forestry and environment vol. 10 no. 02 (2020) 39-50 49 fatih, a. and osman, c., 2010. university students’ attitudes towards environmental problems: a case study from turkey. international journal of physical sciences, 5:2715-2720. fischer, a. and young, j., 2007. understanding mental constructs of biodiversity: implications for biodiversity management and conservation. biological conservation, 136, 271. gambro, j. and switzky, h., 1999. variables associated with american high school students knowledge of environmental issues related to energy and pollution. journal of environmental education, 2:1522. gaston, k. and spicer, j., 2004. biodiversity. oxford university press. gifford, r., hay, r. and boros, k. 1983. individual differences in environmental attitudes. journal of environmental education, 14:19-23. groves, f. and pugh, a., 1999. elementary pre-service teacher perceptions of the greenhouse effect. journal of science education and technology, 8:75-81. hamilton, a., 2005. species diversity or biodiversity? journal of environmental management, 75:89-92. hines, j. hungerford, h. and tomera, a., 1987. analysis and synthesis of research on responsible environmental behavior: a meta-analysis. the journal of environmental education, 18:1-8. hungerford, h. and volk, t., 1990. changing learner behavior through environmental education. the journal of environmental education, 21:8-21. hunter, l. and brehm, l., 2003. qualitative insight into public knowledge of, and concern with. biodiversity. human ecology, 31:309-320. hsu, s. (2004). the effects of an environmental education program on responsible environmental behavior and associated environmental literacy variables in taiwanese college students. the journal of environmental education, 35:37-48. kaiser, f., wolfing, s., and fuhrer, u., 1999. environmental attitude and ecological behavior. journal of environmental psychology, 19:1-19. kuhlemeier, h., bergh, h. and lagerweij, n., 1999. environmental knowledge, attitudes, and behavior in dutch secondary education. the journal of environmental education, 30:4-14. leather, s. and quicke, d., 2009. do shifting baselines in natural history knowledge threaten the environment? environmentalist, 30:1-2. lindemann-matthics, p. and bose, e., 2008. how many species are there? public understanding and awareness of biodiversity in switzerland. human ecology, 36:731-742. macdougall, a.s., mccann, k.s., gellner, g. and turkington, r., 2013. diversity loss with persistent human disturbance increases vulnerability to ecosystem collapse. nature, 494:86-89. mcmillan, e., wright, t. and beazley, k., 2004. impact of university-level environmental studies class on students’ values. the journal of environmental education, 35:19-28. makki, m., abd-el-khalick, f. and boujaoude, s., 2003. lebanese secondary school students’ environmental knowledge and attitudes. environmental education research, 1:21-33. tefera, m., 2011. wildlife in ethiopia: endemic large mammals. world journal of zoology, 6:108-116. ministry of natural resources and tourism (mnrt), 1998. wildlife policy of tanzania. government printers, dar es salaam. nordlund, a.m. and garvill, j., 2002. value structures behind proenvironmental behavior. environment and behavior, 34:740-756. olympia, n. and alexandros, g., 2012. assessing undergraduate university students' level of knowledge, attitudes and behavior towards biodiversity: a case study in cyprus. international journal of science education, 7:1027-1051. roth, c., 1992. environmental literacy: its roots, evolution and directions in the 1990s. columbus, oh: eric clearinghouse for science, mathematics, and environmental education. 50 sivek, d., 2002. environmental sensitivity among wisconsin high school students. environmental education research, 2:155-170. skelly, s. and zajicek, j., 1998. the effect of an interdisciplinary garden program on the environmental attitudes of elementary school students. horttechnology, 8:579-583. spash, c. and hanley, n., 1995. preferences, information, and biodiversity preservation. ecological economics, 12:191-208. tuncer, g., ertepinar, h., tekkaya, c. and sungur, s., 2005. environmental attitudes of young people in turkey: effects of school type and gender. environmental education research, 2:215-233. unced (united nations conference on the human environment), 1992. rio declaration on environment and development. retrieved from www www.unesco.org › education. united nations educational, scientific, and cultural organization and united nations and environment program (unesco and unep), 1978. the tbilisi declaration. connect, 3. williamson, p. and bodle, r., 2016. update on climate geoengineering in relation to the convention on biological diversity: potential impacts and regulatory framework. technical series no. 84. secretariat of the convention on biological diversity, montreal wilke, r., 1995. environmental literacy and the college curriculum. epa journal, 21:28-30. zemede, a., 2004. home-garden and agro-biodiversity. in: eyzaguirre and linares (eds.), the ensetbased home-gardens of ethiopia, smithsonian institution, washington. pp. 123-147. _____________________________________________ *correspondence: sumudumarasinghe@sjp.ac.lk tel: 0777258272 © university of sri jayewardenepura nature-based recreational experiences at coastal wetlands: an application of importance-performance analysis at bundala national park sri lanka s.s. marasinghe* and p.k.p. perera department of forestry and environmental science, university of sri jayewardenepura, nugegoda, sri lanka date received: 23-11-2020 date accepted: 20-12-2020 abstract with the rising demand for nature-based tourism in coastal environments in biodiversity rich tropical countries such as sri lanka, an understanding on visitor perceptions on nature-based tourism performance is vital to ensure sustainable destination development. bundala national park (bnp) is one of the famous tourist destinations which attracts both local and foreign wildlife tourists. however, given the diverse biodiversity features, the wildlife tourism operations at bnp has the potential for sustainable growth. an understanding of the visitor perceptions on current performance of the destination, and visitor expectations is essential in making informed decisions to bridge the performance-expectation gap and develop strategies for sustainable wildlife tourism development based on coastal wetlands in bnp. this study used the importance-performance analysis aided by a self-reporting structured questionnaire to understand visitor motivation, onsite activities and perceptions on the tourism experience. respondents rated ‘to be in a natural setting’ as their main motivation for visiting this destination (79.6%), followed by ‘to observe ecological landscape’ (60.8%), and ‘to learn more about new things/ nature’ (45.3%). viewing wildlife (92.8%), enjoying safari rides (88.4%), and bird watching (82.9%) were the most popular activities among visitors. gap analysis ipa identified significant negative gaps in attributes such as ‘cost of the safari tour’, ‘feeling safe on the safari ride’, ‘guide’s knowledge about the park and flora and fauna’ as well as ‘behaviour of other visitors at the park’, where the performance was below visitor expectations (i.e. performance < importance). overall result of the study highlights the importance of management/regulation of recreational activities and maintaining the quality of natural environment, to enhance the visitor experience and satisfaction. management implications and recommendations are further discussed. keywords: coastal tourism, importance, satisfaction, motivations, visitor perception, wildlife 1. introduction provision of recreational opportunities is an important ecosystem service offered by natural landscapes as people derive recreational benefits from experiencing and admiring the beauty, tranquility and aesthetic of nature (keniger et al., 2013; simpson and newsome, 2017). nature-based recreation and tourism has experienced a significant growth worldwide during the last few decades (buckley, 2004; worboys and gadek, 2004; holden, 2016) as people increasingly find visiting nature-based destinations as a way of “escaping and relaxation” (lee et al., 2004; yoon and uysal, 2005; jensen, 2007; ryu and um, 2009). the literature suggest that people visit nature-based destinations for variety of purposes with the travel motive varying from pure enjoyment to having a meaningful learning experience with nature (kerstetter et al., 2004; perera et al., 2012). the type of leisure experience sought and the “pull” motives 10 marasinghe and perera/ journal of tropical forestry and environment vol. 10 no. 02 (2020) 10-25 are often identified as key determinants of destination selection for recreational activities (bushell and griffin, 2006; perera and vlosky 2013). hence, an understanding of visitors’ needs, expectations, attitudes and motivations is highly important from destination managers’ perspective to enhance the quality of the recreational experience as well as to remain competitive in the nature-based tourism market (mccool, 2002; wardell and moore, 2005). visitor satisfaction plays a vital role in development and long-term sustainability of the tourism business (perera and vlosky, 2013; prakash et al., 2019). visitor satisfaction is described as a result of the comparison between the experience at the destination and the expectations about the destination (pizam et al., 1978). satisfaction or quality of experience is a psychological outcome which is generated by visiting a particular setting/ destination (baker and crompton, 2000; howat and crilley, 2007; žabkar et al., 2010). satisfaction leads to destination loyalty of nature-based tourists (del bosque and san martin, 2008; wang et al., 2009; rivera and croes 2010), destination choice (tian-cole and crompton, 2003; kozak and rimmington, 2000) and future beheviour (cole et al., 2002; cole and scott, 2004; yoon and uysal, 2005; lee, 2007, 2009; lee et al., 2007). thus, a tourist who is satisfied with the tourism experience, tends revisit or recommends the destination to others (oppermann, 2000; rittichainuwat et al., 2002; tian-cole et al., 2002; gupta et al., 2007; jang and feng, 2007; he and song, 2009; wu and liang, 2009). repeat visitation offers potential for a more stable revenue base (swanson and hsu, 2009; žabkar et al., 2010). visitor surveys are among the most commonly used tools to obtain detailed information about the characteristics, preferences, expectations and experience of the visitors to a particular destination. outcomes of such surveys have wide implications in tourism planning, management, resource allocation, interpretation and marketing (baker and crompton, 2000; tarrant and smith, 2002; wardell and moore, 2005; bushell and griffin, 2006). importance-performance analysis (ipa) developed by martilla and james (1977) is one of the popular techniques which utilises visitor surveys to examine customer satisfaction and management strategies at tourism destinations. it is based on the mean performance and mean importance obtained from surveyed respondents for each of several attributes or characteristics of a service or product. this technique is widely accepted because of its ease of application and ability to present strategic recommendations together with data (oh, 2001). ipa has gained popularity in fields of research such as travel and tourism (tonge and moore, 2007; wade and eagles, 2010; newsome et al., 2019), leisure and recreation (hollenhorst et al., 1992; hudson and shephard, 1998; tarrant and smith, 2002; daniels and marion, 2006; marasinghe et al., 2021). this technique is extensively used to understand visitor satisfaction and expectations (i.e., wade and eagles, 2003; eskidsen and kristensen, 2006; deng, 2007; taplin, 2012; azzopardi and nash, 2013; lai and hitchcock, 2015; zhang and chan, 2016; birendra et al., 2018; frleta and jurdana, 2018; soldić frleta, 2018; rose and basri, 2019; marasinghe et al., 2021). understanding visitor characteristics, behaviors, perceptions, preferences and satisfaction are essential in the development and delivery of quality nature-based tourism experiences in the context of rapidly growing nature-based tourism in sri lanka (perera et al., 2012; perera and vlosky, 2013; senevirathna and perera, 2013; perera et al., 2015; rathnayake, 2015). however, limited studies thus far have attempted to understand the visitor perception on management of recreational activities and natural environment, expectations and satisfaction of nature-based tourists visiting coastal wetland destinations in the country (marasinghe et al., 2021). moreover, some studies suggested that, majority of visitors to national parks in sri lanka, is dissatisfied with the park management and tour operational activities (prakash et al., 2019). however, there are no recent studies carried out to evaluate the quality of visitor experience at bnp, a well-known destination for birdwatching and wildlife tourism. hence, this study aimed to examine the visitors' level of satisfaction regarding the safari wildlife tourism experience at 11 bundala national park and to identify their attitudes, motivation and knowledge on environmental concepts in order to shape management actions to improve the quality of recreational experience while conserving the natural ecosystem. this study thus makes a significant contribution towards expanding the limited literature on visitor studies on nature-based tourism in coastal birding destinations of sri lanka. 2. materials and methods 2.1. study site bundala national park (bnp) and the sanctuary spans over 6,216ha, and lies on the coast of hambantota district in southern province (figure 1). it is of international significance for migrating birds and declared as a ramsar wetland in october 1990. bnp is managed by the department of wildlife conservation with the main scope of biodiversity conservation while allowing the responsible recreational and educational opportunities for visitors (dwc, 2008). three topographic zones can be identified in wetland-dominated bnp; (1) beach and sand dunes, (2) outer coastal plains with lagoons and (3) inner coastal plains. mean annual rainfall in bnp ranges from 900 mm to 1,300 mm, with two peaks periods of rainfall in april–may and october-november, and an extensive intervening dry period between may and september. it has a diverse vegetation, showing a natural succession from low, creeping plants that have colonised the beach and sand dunes to climax forest as thorn, dry semi-evergreen and dry-mixed evergreen. additionally salt marshes, mangrove and aquatic vegetation can be identified in the lagoons and low lying areas (bambaradeniya et al., 2002). figure 1. location map of bundala national park. with a staggering 165 recorded bird species, the bnp is regarded as one of the premier bird watching destinations in sri lanka. out of the total bird species recorded, approximately 27 % is migratory 12 marasinghe and perera/ journal of tropical forestry and environment vol. 10 no. 02 (2020) 10-25 birds while 0.01% is endemic to the country (dwc, 2008). large flocks of migrating greater flamingos (phoenicopterus roseus) is one of the key biodiversity features of the bnp, which attracts thousands of local and foreign birders each year. for instance, the total number of visitors to the bnp was 18,629 in 2019 where foreign visitors accounted for 46% of total visitors (sltda 2020). visitations to the park is typical done in four-wheel drive jeeps operated by safari jeep owners/services or private vehicles. a guide employed by the department of wildlife conservation join each tour group/jeep at the gates for both safety and nature interpretation purposes, in line with the visitor policy of the park. 2.2. development of research instrument a structured questionnaire was used as the primary research instrument to gather information on visitor demographics, trip characteristics, visitor motivations, intended behaviors, and their level of satisfaction and importance of specific attributes pertaining to a wetland tourism experience. closedended questions were used to explore visitor motivations, the importance and satisfaction with their experience. the responses were measured on a 5-point likert scale from 1 (not at all important) to 5 (extremely important). openended questions were included to the questionnaire to gain the extended ideas and views of visitors on wildlife tourism management at bundala national park. the 18 attributes were selected for the ipa, after a thorough review of the literature (deng, 2007; mcguiness et al., 2017; newsome et al, 2019; vaske et al., 2009; zhang and chan, 2016) and modified according to the study site context. the questionnaire was pre-tested using a sample of 25 visitors and further revised before it was administered at the site. 2.3. sampling and data collection data collection was conducted from november 2017 to april 2018 and november 2018 to march 2019 (tourist season), predominantly on weekends where higher visitor numbers were anticipated. the self-report questionnaire was administered to visitors arriving at the park. two field workers were employed to distribute the questionnaires and visitors were provided with the questionnaire prior to starting their safari ride, while at the waiting area of the visitor center at the park office. all members of each visitor group entering the sampling location were informed about the survey and asked about their willingness to participate. only one member from each visitor group, who was over 18 years of age, and who volunteered themselves to participate were provided with a questionnaire. those who declined to participate in the survey and unreturned questionnaires were considered as non-respondents. a total of 300 questionnaires were administered over the study period. 2.4. data analysis data were cleaned by performing a consistency check before proceeding to detailed analysis. incomplete questionnaires with many missing responses were discarded. data were statistically analysed using ibm® spss® statistics 20 software and descriptive analysis (i.e. mean, percentages and comparisons) was carried out using microsoft excel. data set was tested for validity by using exploratory factor analysis (kaiser-meyer-oklin measure of sampling adequacy=0.870) and for reliability by using cronbach's alpha reliability test (cronbach’s alpha=0.812). importance-performance analysis (ipa) technique (martilla and james, 1977) was used to evaluate 18 selected attributes related to recreational experience of visitors to bundala national park. ipa matrix consists of four quadrants (see figures 4 and 5) as follows: quadrant (i)–high importance and high performance (keep up good work); quadrant (ii)– low importance and high performance (possible overkill); quadrant (iii)–low importance and low performance (low priority); and quadrant (iv)–high importance and low performance (concentrate here). gap analysis ipa is a further development of this ipa technique, which quantitatively assesses the significance of the differences between visitor expectations (importance) and the performance of an attribute via a one-sample t-test (taplin, 2012; simpson at al., 2019). this study utilised the scale-centered 13 and data-centered ipa along with gap analysis to quantify and visualise visitor satisfaction with their birdwatching safari jeep ride experience at bnp (mcguiness et al., 2017; parker and simpson, 2018; simpson et al. 2019). results from the gap analysis were graphed on a hybrid data-centered and gap analysis ipa matrix to further elaborate the findings (taplin, 2012; parker and simpson 2018; simpson et al., 2019). 3. results out of the 300 visitors approached at the entrance of the park, a total of 192 individuals participated in the survey, which accounted for a response rate of 64%. there were 181 usable questionnaires with 11 questionnaires discarded as they were incomplete or responses were inconsistent, hence the adjusted response rate was 60.3%. statistical tables were applied to determine the sample error made in the population and it was 5.7% for a confidence level of 95% (bigne et al., 2001). 3.1. visitor profile and trip characteristics general respondent socio-demographic characteristics are summarised in table 1. the respondents were dominated by young to middle-age, welleducated, male visitors. most respondents were between ages 26 and 45 (74.5%). approximately 81% of the respondents had attained an education level of university/college degree or above. most respondents (91.2%) were first time visitors to bnp. the majority (92.9%) of the visitor groups represented in the sample were specifically visiting the destination for a wildlife tourism experience. however, 97.2% of the respondents had undertaken wildlife tourism experience elsewhere. for 91% of respondents, bnp was one of several destinations of their trip and for 9% respondents it was not a planned destination of their trip (table 1). table 1: general respondent socio-demographic profile and trip characteristics (n=181). visitor characteristics percentage (%) visit characteristics percentage (%) age group trip planning 18-25 years 3.0 main destination of trip 0.0 26-35 years 29.0 one of several on trip 91.0 36-45 years 45.6 not a planned destination 9.0 46 or older 22.4 first visit to bnp gender yes 91.2 male 62.0 no 8.8 female 38.0 trip specifically for wildlife tourism highest education level attained yes 92.9 primary --no 7.1 high school 18.9 university/college 74.0 previously undertaken wildlife tour postgraduate 7.1 yes 97.2 no 2.8 monthly income less than 200 usd 14.5 200-500 usd 8.1 500-1,000 usd 1.1 1,000-2,000 usd 38.7 more than 2,000 usd 37.6 14 marasinghe and perera/ journal of tropical forestry and environment vol. 10 no. 02 (2020) 10-25 3.2. visitor motives and desired activities visitors were asked to indicate their main motivations for visiting the bnp. approximately 79.6% of respondents cited “to be in a natural setting” as their motivation for visiting bnp followed by “to observe ecological landscapes” (60.8%) and “to learn more about new things/ nature” (45.3%) (figure 2). as indicated in figure 3, “viewing wildlife” (92.8%) was the top-ranked activity undertaken by visitors, followed by enjoying safari rides (88.4%) and bird watching (82.9%). figure 2. motivations of respondents for visiting bundala national park (n=181 with multiple responses possible). \ figure 3. activities undertaken by the respondents at bundala national park (n=181 with multiple responses possible). 3.3. overall visitor satisfaction the results of the scale-centered ipa in general suggest that the destination is performing well with all 16 attributes placed in “keep up good work” quadrant (figure 4). this shows that visitors placed high importance on all 18 attributes and of the performance of those attributes was meeting or exceeding visitor expectations. this is further reflected in all of respondents rating their overall satisfaction on the positive side of likert scale (mean score = 4.57) and strong levels of support for personal recommendation (mean score=4.65) and revisit intention (92.9%) for bundala national park (table 2). 0 10 20 30 40 50 60 70 80 90 to conduct survey or research to educate the children to memorize the past experience to use free time to be with my (our) family or friends to get away from crowd and noise to learn more about new things/ nature to observe ecological landscape to be in a natural setting percentage of respondents (%) 0 20 40 60 80 100 environmental education appreciating nature and scenery photography bird watching enjoying safari rides viewing wildlife percentage of respondents (%) 15 figure 4. scale-cantered ipa (martilla and james, 1977) for nature-based tourism focused safari rides at bundala national park. table 2: overall level of satisfaction, personal recommendation, and revisit intention reported by respondents (n=181). mean/percentage overall, how satisfied are you with your visit to bundala national park? 4.57 (5-point likert scale) this visit offered a good value for the money spent 4.18 (5-point likert scale) how strongly would you recommend this experience to friends who share your interests? 4.65 (5-point likert scale) would you come back and visit bundala national park again? yes = 92.9% no = 7.1% the results of the enhanced ipa and gap analysis for all 18 attributes are reported in table 3 and the data-cantered and gap analysis ipa matrix is presented in figure 5. table 3: mean levels of importance (i) and performance (p) and the resulting gap (p–i) with attributes ordered from largest negative to largest positive gap in performance. code attribute n i p gap t-statistic p-value 1 ability to have a once in a lifetime wildlife experience 181 3.82 4.56 0.74 3.764 0.014* 2 abundance of wildlife 181 4.34 4.66 0.32 4.101 0.002* 3 proximity to wildlife 181 4.45 4.66 0.21 5.082 0.004* 4 proximity to birds 181 4.42 4.62 0.20 5.080 0.000* 5 number of animals seen 181 4.39 4.57 0.18 5.522 0.000* 6 waiting time for ticketing procedures at the park gates 181 4.18 4.62 0.44 5.421 0.000* 1 2 3 4 5 1 2 3 4 5 im p o rt a n c e performance concetrarte here keep up good work low priority overkill/ exceeds expectations 16 marasinghe and perera/ journal of tropical forestry and environment vol. 10 no. 02 (2020) 10-25 code attribute n i p gap t-statistic p-value 7 number of passengers in the safari vehicle 181 4.06 4.73 0.67 3.620 0.007* 8 number of other safari vehicles/visitor traffic inside the park 181 4.47 4.53 0.06 3.654 0.016* 9 duration of the safari tour 179 4.56 4.57 0.01 3.278 0.039* 10 cost of the safari tour 170 4.55 3.93 -0.62 3.448 0.010* 11 interesting and informative guided tour 176 4.69 4.70 0.01 5.020 0.000* 12 feeling safe on the guided tour 181 4.69 4.53 -0.16 4.790 0.000* 13 clear information about visitor safety 181 4.50 4.65 0.15 5.673 0.000* 14 useful information on flora and fauna 181 4.37 4.52 0.15 5.702 0.000* 15 guide’s knowledge of the about park and flora and fauna 181 4.69 4.59 -0.10 6.400 0.000* 16 overall cleanliness of the park 181 4.67 4.66 -0.01 4.887 0.000* 17 quality of the nature trails inside the park 181 4.46 4.47 0.01 3.424 0.025* 18 other visitors generally well behaved 156 4.69 4.46 -0.23 5.321 0.000* figure 5. ipa matrix for the attributes of the birding/wildlife safari jeep tours at bundala national park reported in table 3. cross-hairs are place at the mean values for the importance and performance of the attributes. 1 2 34 5 6 7 8 910 11 12 13 14 15 16 17 18 3.7 3.8 3.9 4 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 3.9 4 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 im p o rt a n c e performance concetrarte here keep up good work low priority overkill/ exceeds expectations 17 3.4. visitor satisfaction with wildlife safari operation the results of data-cantered ipa matrix (figure 5) suggest that attributes associated with the operation of the safari jeep rides are performing well. “duration of the safari tour” (9), “feeling safe on the guided tour” (12), “clear information about visitor safety” (13), are located in quadrant i (keep up good work). however, “cost of the safari tour” (10) is in quadrant iv (concentrate here) thus, warrant some corrective management action. “number of animals seen” (5) and “waiting time for ticketing procedures at the park gates” (6), are located in quadrant ii (possible overkill), and those attributes appear to have exceed visitor expectations, with the significant over-performance (i.e. performance > importance). those findings were in line with the responses of visitors for the questions which were specifically asked about overall satisfaction about the safari ride operations. most respondents (98.9%) rated the safari jeep driver’s behaviour and compliance with safety and operation rules as being acceptable or excellent and approximately 94.5% stated that the speed of the safari jeep was acceptable or “about right”. however, as revealed by the data-centred and gap analysis ipa matrix, “feeling safe on the guided tour” (12) and “cost of the safari tour” (10) have significant negative performance gaps (i.e. importance > performance) and the “cost” is the worst performed attribute among all 18 attributes considered for the study. the results are contradictory for attribute 12 and attribute 13. although the visitors were satisfied with clear information provided on safety, the majority of the respondents couldn’t meet expected level of feeling of their safety during the tour. 3.5. visitor satisfaction with the nature-based attributes according to data-centred ipa matrix (figure 5), nature-based attributes associated with safari rides such as, “proximity to wildlife” (3) and “proximity to birds” (4) appear in the optimal quadrant i (keep up good work), while “ability to have a once in a lifetime wildlife experience” (1) and “abundance of wildlife” (2) have exceed visitor expectations, with the significant over-performance (i.e. performance > importance) of that attribute locating it in quadrant ii. 3.6. visitor satisfaction with the information/interpretation provided “interesting and informative guided tours” (11) and “guide’s knowledge about park and flora and fauna’ (15) were located in quadrant i (keep up good work). but according to data-cantered gap analysis ipa matrix, a significant negative performance gap (i.e. importance > performance) was recorded for the attribute “guide’s knowledge about the park and flora and fauna” (15), despite being located in the keep up good work quadrant. however, the attribute “useful information on flora and fauna” (14) appears in the quadrant ii, where performance exceeds visitor expectations. 3.7. visitor satisfaction with the operating/destination environment when considering the visitors’ perception on the destination management, “quality of the nature trails inside the park” (17) and “other visitors generally well behaved” (18) are located in the quadrant iv (concentrate here), thus which should be considered when setting priorities for corrective management action. “number of other safari vehicles/visitor traffic inside the park” (8) and “overall cleanliness of the park” (16) are located in quadrant i (keep up good work). but interestingly, though, “overall cleanliness of the park” (16) appears in the keep up good work quadrant, a significant negative performance gap (i.e. importance > performance) was recorded for that attribute. therefore attention of park management should be paid to maintain the cleanliness inside the park. moreover, “number of passengers in the safari vehicle” (7) has exceeded visitor expectations, with the significant over-performance (i.e. performance > importance). further, when specifically asked about the level of safari jeep traffic observed during their tour, 85% of the respondents stated that the level of traffic was “just about right” and only 3.3% reported that there were “too many” safari jeeps for their liking. those finding agree with the outcome of the ipa that visitors were satisfied with the “number of other safari vehicles/visitor traffic inside the park” (8). 18 marasinghe and perera/ journal of tropical forestry and environment vol. 10 no. 02 (2020) 10-25 furthermore, another question was asked from visitors about what they think is the optimum number of jeeps they would like to see inside the park and how many jeeps they observed during their safari ride. approximately 54.2% of respondents stated that they would have preferred to see five or less number of jeeps on their ride while another 30.9% respondents preferred to see three or less number of safari jeeps (figure 6). the majority of respondents (40.9%) reported seeing less than five jeeps, during their ride. figure 6. number of jeeps encountered by the respondents during their safari ride at bundala national park and their perceived optimum number of jeeps (n=181). 3.8. overall perceptions of nature-based tourism management respondents were asked to rank their responses to the three questions reported in table 4 using a 5-point likert scale anchored by 1=highly disagree, 2=disagree, 3=neither agree nor disagree, 4=agree and 5=highly agree. the tight clustering of the results (narrow 95% confidence interval) about the mean values aligned to the rating of “agree”. table 4: visitor perceptions on management of nature-based tourism at bundala national park (n=181). statement mean ±95%ci sufficient actions are taken to protect the park 4.28 0.10 sufficient actions are taken to protect the wild life inside the park 4.36 safari jeep rides are well regulated and managed 4.40 0.09 birds and other wildlife in the park are disturbed by the visitors 3.65 wildlife tourism in the bundala park is a good example of environmentally responsible travel 4.44 0.10 4. discussion 4.1 visitor satisfaction the outcome of the ipa-based survey revealed several important trends on wildlife and birding tour operations at the bnp. even though, wildlife and birding safari jeep rides are providing a “once in a lifetime wildlife tourism experience” to visitors exceeding their expectations, several aspects of the experience are falling short of visitor expectations which can result in negative impacts on destination 0 20 40 60 < 2 jeeps 2-3 jeeps 4-5 jeeps > 5 jeeps p e rc e n ta g e o f r e sp o n d a n ts number of safari jeeps encountered prefered number of safari jeeps 19 image and loyalty. as revealed by the visitors’ responses, “cost of the safari ride” is the top priority for corrective management action at bnp since it was the least performed attribute which had the highest negative performance gap. credibility concerns can be raised especially among foreign visitors, because of the present discrepancy in prices of safari rides and two-tiered pricing adopted by private safari vehicle owners at the destination, and this can result in visitor dissatisfaction (laarman and gregersen, 1996; walpole et al., 2001). hence, safari ride operations should be standardised by encouraging the service providers to clearly communicate the tour package details via printed, verbal and online means, thus the visitors will be well-informed about the tour before making the purchasing decisions. moreover, aspects such as quality of the nature trails and behaviour of the visitors also should be taken in to the consideration to enhance the visitor experience. according to ipa results, “proximity to wildlife” and “proximity to birds” were positioned in the optimal quadrant with significant positive performance gaps. though it is plus point when considering about the visitor satisfaction, safari vehicles getting in close proximity to wildlife, especially birds, can have negative impacts on their general behaviour (schlacher et al., 2013; burger and niles, 2013; martín et al., 2015; marasinghe et al., 2020). hence, it is necessary to minimise disturbance on avifauna and their habitats, through introducing appropriate guidelines for safari ride operations, by considering the flight response distances of birds and speed limits of the safari vehicles (velando and munila, 2011; burger and niles, 2013; le corre et al., 2013). furthermore, nature interpretation has been recognised as an important component in sustainable nature-based tourism development (hwang et al., 2005; ham and weiler, 2012; wang, 2015; zhang and chan, 2016; mutanga et al., 2017). the significant negative performance gap recorded for “guide’s knowledge about the park and flora and fauna” indicates the need for more organized and well-planned out mechanism for nature interpretation in the park. the management can introduce professional training for safari ride operators, safari jeep riders and guides to ensure ethical, legal environmentally responsible, safe and educative tour experiences (prakash et al., 2019), which ultimately leads to enhanced levels of visitor satisfaction. 4.2 perception of visitors on recreational management a number of attributes under the direct control of the park management (i.e., “waiting time for ticketing procedures at the park gates”, “number of passengers in the safari vehicle”, “number of other safari vehicles/visitor traffic inside the park”, “interesting and informative guided tour” and “clear information about visitor safety”) recorded significant positive performance gaps (importance < performance). these outcomes are in line with the survey finding of which, the majority of the visitors were satisfied with the nature-based tourism experience provided at the destination (measured using a single item/statement in the questionnaire). though the visitors to bnp were satisfied with the clear information provided on the safety, the results suggest that safety attributes fell below the visitor expectations. the negative gap between the expectations of visitors’ personal safety and underperformance, may be due to the speed and condition of some safari jeeps and the ‘reckless’ driving of some drivers. on the other hand, the results revealed that, the personal safety of visitors is one of the major and sensitive aspects, which should be fulfilled to meet the visitor satisfaction. hence, an overall improvement on actions on passenger safety and safety instructions during the tour should be considered as a priority. “overall cleanliness of the park” also couldn’t meet the visitors’ expected level of performance, indicating the need for closer attention and management actions to maintain the natural environment of bnp clean. 20 marasinghe and perera/ journal of tropical forestry and environment vol. 10 no. 02 (2020) 10-25 4.3 visitors’ knowledge on environmental concepts attributes such as, “ability to have a once in a lifetime wildlife experience”, “abundance of wildlife”, “number of animals seen” and “useful information on flora and fauna” achieving the visitor satisfaction by exceeding their expectations (importance < performance) possibly hints the less environmentally oriented motives of visitors, in appreciating what the destination has to offer. hence, the dominant segment of visitors to bnp, can be identified as “picnickers”, those who visit nature-based destinations purely for enjoyment, with less desire to have a nature-based learning experience (perera et al., 2012). this may further explain visitors placing less importance on nature interpretation and learning related attributes. 4.4 limitations of the study a personal interview with visitors at the end of the safari tour would have yielded more accurate views of the visitors on current and desired performance of the destination. however, due to the practical difficulty in intercepting visitors at the exit of the park, this study relied on a self-reporting questionnaire. furthermore, the sampling technique employed in the study did not capture adequate number of nonenglish speaking foreign visitors as a result of constraints in translating the questionnaires in to different languages. hence the sample captured in this study represents only a section of the international visitors to bundala national park. only the foreign visitor segment was considered for the analysis due to inadequate sample size of domestic visitors. 5. conclusion this study utilised ipa techniques to evaluate visitor perceptions of tourism operations at a coastal wetland tourism destination with the aim of identifying high and low priority/performance attributes. though the visitors to bundala national park, are generally satisfied with their experience, several underperforming attributes were identified (i.e. visitor safety, cost of the safari ride, quality of the nature trails, overall cleanliness of the park and guides’ knowledge about flora and fauna). those visitor concerns need managerial attention to lift visitor satisfaction levels and ensure future destination development within the framework of sustainable tourism. the findings emphasise the importance of the protection of the environment in line with recreation. this study suggests several management implications to improve the quality of the recreational experience as well as the image of the destination such as, introducing effective safety guidelines, improving professional standards and interpretation skills of tour guides and adopting more transparent and appropriate pricing strategies for safari jeep rides. references azzopardi, e. and nash, r., 2013. a critical evaluation of importance–performance analysis. tourism management, 35:222-233. baker, d.a. and crompton, j.l., 2000. quality, satisfaction and behavioral intentions. annals of tourism research, 27:785-804. bambaradeniya, c.n.b., ekanayake, s.p., fernando, r.h.s.s., perera, w.p.n. and somaweera, r., 2002. a biodiversity status profile of bundala national park-a ramsar wetland in sri lanka. occasional paper of iucn sri lanka. bigne, j.e., sanchez, m.i. and sanchez, j., 2001. tourism image, evaluation variables and after purchase behaviour: inter-relationship. tourism management, 22:607-616. birendra, k.c., paudyal, r. and neupane, s.s., 2018. residents’ perspectives of a newly developed ecotourism project: an assessment of effectiveness through the lens of an importance–performance analysis. asia pacific journal of tourism research, 23:560-572. buckley, r. 2004. impacts of ecotourism on birds. environmental impacts of ecotourism, 187-209. 21 burger, j. and niles, l., 2013. shorebirds and stakeholders: effects of beach closure and human activities on shorebirds at a new jersey coastal beach. urban ecosystems, 16:657-673. bushell, r. and griffin, t., 2006. monitoring visitor experiences in protected areas. international journal of protected area management, 16:25-33. cole, s.t., crompton, j.l. and willson, v.l., 2002. an empirical investigation of the relationships between service quality, satisfaction and behavioral intentions among visitors to a wildlife refuge. journal of leisure research, 34:1-24. cole, s.t. and scott, d., 2004. examining the mediating role of experience quality in a model of tourist experiences. journal of travel and tourism marketing, 16:79-90. daniels, m.l. and marion, j.l., 2006. visitor evaluations of management actions at a highly impacted appalachian trail camping area. environmental management, 38:1006-1019. del bosque, i.r. and san martín, h., 2008. tourist satisfaction a cognitive-affective model. annals of tourism research, 35:551-573. deng, w., 2007. using a revised importance–performance analysis approach: the case of taiwanese hot springs tourism. tourism management, 28:1274-1284. dwc, 2008. biodiversity baseline survey: bundala national park. consultancy services report prepared bygreen, m.j.b. (ed.), de alwis, s.m.d.a.u., dayawansa, p.n., how, r., padmalal, u.k.g.k., singhakumara, b.m.p., weerakoon, d. and wijesinghe, m.r. infotechs ideas in association with greentech consultants. sri lanka protected areas management and wildlife conservation project (pam&wcp/consult/02/bdbs), department of wildlife conservation, ministry of environment and natural resources, colombo. pp. 46. eskidsen, j.k. and kristensen, k., 2006. enhancing importance performance analysis. international journal of productivity and performance management, 55:40-60. frleta, d.s. and jurdana, d.s., 2018. seasonal variation in urban tourist satisfaction. tourism review. gupta, s., mclaughlin, e. and gomez, m., 2007. guest satisfaction and restaurant performance. cornell hotel and restaurant administration quarterly, 48:284-298. ham, s.h. and weiler, b., 2012. interpretation as the centerpiece of sustainable wildlife tourism. sustainable tourism. butterworth-heinemann, oxford, 35-44. he, y. and song, h., 2009. a mediation model of tourists' repurchase intentions for packaged tour services. journal of travel research, 47:317-331. holden, a., 2016. environment and tourism. routledge, london, united kingdom. hollenhorst, s.j., olson, d. and fortney, r., 1992. use of importance-performance analysis to evaluate state park cabins: the case of the west virginia state park system. journal of park and recreation administration, 10:1-11. howat, g. and crilley, g., 2007. customer service quality, satisfaction, and operational performance: a proposed model for australian public aquatic centres. annals of leisure research, 10:168-195. hudson, s. and shephard, g.w., 1998. measuring service quality at tourist destinations: an application of importance-performance analysis to an alpine ski resort. journal of travel and tourism marketing, 7:61-77. hwang, s.n., lee, c. and chen, h.j., 2005. the relationship among tourists’ involvement, place attachment and interpretation satisfaction in taiwan’s national parks. tourism management, 26:143-156. jang, s.s. and feng, r., 2007. temporal destination revisit intention: the effects of novelty seeking and satisfaction. tourism management, 28:580-590. jensen, j.m., 2007. an empirical investigation of the relationships between hygiene factors, motivators, satisfaction, and response among visitors to zoos and aquaria. tourism review international, 11:307-316. 22 marasinghe and perera/ journal of tropical forestry and environment vol. 10 no. 02 (2020) 10-25 keniger, l.e., gaston, k.j., irvine, k.n. and fuller, r.a., 2013. what are the benefits of interacting with nature?. international journal of environmental research and public health, 10:913-935. kerstetter, d.l., hou, j.s. and lin, c.h., 2004. profiling taiwanese ecotourists using a behavioral approach. tourism management, 25:491-498. kozak, m. and rimmington, m., 2000. tourist satisfaction with mallorca, spain, as an off-season holiday destination. journal of travel research, 38:260-269. lai, i.k.w. and hitchcock, m., 2015. importance–performance analysis in tourism: a framework for researchers. tourism management, 48:242-267. laarman, j.g. and gregersen, h.m., 1996. pricing policy in nature-based tourism. tourism management, 17:247-254. le corre, n., peuziat, i., brigand, l., gélinaud, g. and meur-férec, c., 2013. wintering waterbirds and recreationists in natural areas: a sociological approach to the awareness of bird disturbance. environmental management, 52:780-791. lee, t.h., 2007. ecotourism behavioral model of national forest recreation areas in taiwan. international forestry review, 9:771-785. lee, t.h., 2009. a structural model to examine how destination image, attitude, and motivation affect the future behavior of tourists. leisure sciences, 31:215-236. lee, c.k., lee, y.k. and wicks, b.e., 2004. segmentation of festival motivation by nationality and satisfaction. tourism management, 25:61-70. lee, c.k., yoon, y.s. and lee, s.k., 2007. investigating the relationships among perceived value, satisfaction, and recommendations: the case of the korean dmz. tourism management, 28:204214. marasinghe, s., perera, p., simpson, g.d. and newsome, d., 2021. nature-based tourism development in coastal wetlands of sri lanka: an importance–performance analysis at maduganga mangrove estuary. journal of outdoor recreation and tourism, 33:100345. marasinghe, s., simpson, g., newsome, d. and perera, p., 2020. scoping recreational disturbance of shorebirds to inform the agenda for research and management in tropical asia. tropical life sciences research, 31:51-78, 202. martilla, j.a. and james, j.c., 1977. importance-performance analysis. journal of marketing, 41:77-79. martín, b., delgado, s., de la cruz, a., tirado, s. and ferrer, m., 2015. effects of human presence on the long‐term trends of migrant and resident shorebirds: evidence of local population declines. animal conservation, 18:73-81. mccool, s.f., 2002. tourism in protected areas: continuing challenges and emerging issues for sustaining visitor experiences. celebrating mountains, jindabyne, australia, 26. mcguiness, v., rodger, k., pearce, j., newsome, d. and eagles, p.f., 2017. short-stop visitation in shark bay world heritage area: an importance–performance analysis. journal of ecotourism, 16:24-40. mutanga, c.n., vengesayi, s., chikuta, o., muboko, n. and gandiwa, e., 2017. travel motivation and tourist satisfaction with wildlife tourism experiences in gonarezhou and matusadona national parks, zimbabwe. journal of outdoor recreation and tourism, 20:1-18. newsome, d., rodger, k., pearce, j. and chan, k.l.j., 2019. visitor satisfaction with a key wildlife tourism destination within the context of a damaged landscape. current issues in tourism, 22:729746. oh, h., 2001. revisiting importance–performance analysis. tourism management, 22:617-627. oppermann, m., 2000. tourism destination loyalty. journal of travel research, 39:78-84. parker, j. and simpson, g.d., 2018. visitor satisfaction with a public green infrastructure and urban nature space in perth, western australia. land, 7:159. 23 perera, p., senevirathna, m.c. and vlosky, r.p., 2015. recreationist perspectives, attitudes, and perceptions towards national park management in sri lanka. turizam: međunarodni znanstvenostručni casopis, 63:497-514. perera, p. and vlosky, r., 2013. how previous visits shape trip quality, perceived value, satisfaction, and future behavioral intentions: the case of forest-based ecotourism in sri lanka. international journal of sport management, recreation and tourism, 11. perera, p., vlosky, r.p. and wahala, s.b., 2012. motivational and behavioral profiling of visitors to forestbased recreational destinations in sri lanka. asia pacific journal of tourism research, 17:451467. pizam, a., neumann, y. and reichel, a., 1978. dimentions of tourist satisfaction with a destination area. annals of tourism research, 5:314-322. prakash, s.l., perera, p., newsome, d., kusuminda, t. and walker, o., 2019. reasons for visitor dissatisfaction with wildlife tourism experiences at highly visited national parks in sri lanka. journal of outdoor recreation and tourism, 25:102-112. rathnayake, r.m.w., 2015. how does ‘crowding’affect visitor satisfaction at the horton plains national park in sri lanka?. tourism management perspectives, 16:129-138. rittichainuwat, b.n., qu, h. and mongknonvanit, c., 2002. a study of the impact of travel satisfaction on the likelihood of travelers to revisit thailand. journal of travel and tourism marketing, 12:19-43. rivera, m. a. and croes, r., 2010. ecotourists' loyalty: will they tell about the destination or will they return?. journal of ecotourism, 9:85-103. rose, r.a.c. and basri, n.e.a., 2019. analisis tahap kepuasan pengunjung di taman rekreasi awam sabah (analysis of visitor satisfaction levels in sabah recreational public parks). geografia-malaysian journal of society and space, 15:336-349. ryu, s. and um, s., 2009. the reexamination of the relationship between tourist satisfaction and revisit intention: the mediating effect of changed attitude. journal of tourism and leisure research, 21:89-104. schlacher, t.a., weston, m.a., lynn, d. and connolly, r.m., 2013. setback distances as a conservation tool in wildlife-human interactions: testing their efficacy for birds affected by vehicles on opencoast sandy beaches. plos one, 8:p.e71200. senevirathna, h.m.m.c. and perera, p.k.p., 2013. wildlife viewing preferences of visitors to sri lanka’s national parks: implications for visitor management and sustainable tourism planning. journal of tropical forestry and environment, 3:1-10. simpson, g. and newsome, d., 2017. environmental history of an urban wetland: from degraded colonial resource to nature conservation area. geo: geography and environment, 4:e00030. simpson, g.d., patroni, j., teo, a.c., chan, j.k. and newsome, d., 2019. importance-performance analysis to inform visitor management at marine wildlife tourism destinations. journal of tourism futures. soldić frleta, d., 2018. shifts in tourists’ attitudes towards the destination offering. tourism and hospitality management, 24:257-270. sri lanka tourism development authority (sltda)., 2020. annual statistical report 2019 (provisional release). https://www.sltda.gov.lk. accessed 10 october 2020. swanson, s.r. and hsu, m.k., 2009. critical incidents in tourism: failure, recovery, customer switching, and word‐of‐mouth behaviors. journal of travel and tourism marketing, 26:180-194. taplin, r.h., 2012. competitive importance-performance analysis of an australian wildlife park. tourism management, 33:29-37. 24 https://www.sltda.gov.lk/ marasinghe and perera/ journal of tropical forestry and environment vol. 10 no. 02 (2020) 10-25 tarrant, m.a. and smith, e.k., 2002. the use of a modified importance-performance framework to examine visitor satisfaction with attributes of outdoor recreation settings. managing leisure, 7:6982. tian-cole, s. and cromption, j. 2003. a conceptualization of the relationships between service quality and visitor satisfaction, and their links to destination selection. leisure studies, 22:65-80. tian-cole, s., crompton, j.l. and willson, v.l. 2002. an empirical investigation of the relationships between service quality, satisfaction and behavioral intentions among visitors to a wildlife refuge. journal of leisure research, 34:1-24. tonge, j. and moore, s.a. 2007. importance-satisfaction analysis for marine-park hinterlands: a western australian case study. tourism management, 28:768-776. vaske, j.j., kiriakos, r., cottrell, s.p. and khuong, m.n. 2009. importance‐performance and segmentation: an application at a biosphere reserve in vietnam. journal of travel tourism marketing, 26:30-41. velando, a. and munilla, i. 2011. disturbance to a foraging seabird by sea-based tourism: implications for reserve management in marine protected areas. biological conservation, 144:1167-1174. wade, d.j. and eagles, p.f. 2003. the use of importance–performance analysis and market segmentation for tourism management in parks and protected areas: an application to tanzania's national parks. journal of ecotourism, 2:196-212. walpole, m.j., goodwin, h.j. and ward, k.g. 2001. pricing policy for tourism in protected areas: lessons from komodo national park, indonesia. conservation biology, 15:218-227. wang, w.c. 2015. visitor perception, interpretation needs, and satisfaction of eco-tourism: the case of taijiang national park, taiwan. enlightening tourism. a pathmaking journal, 5:180-200. wang, x., zhang, j., gu, c. and zhen, f. 2009. examining antecedents and consequences of tourist satisfaction: a structural modeling approach. tsinghua science and technology, 14:397-406. wardell, m.j. and moore, s.a. 2005. collection, storage and application of visitor use data in protected areas: guiding principles and case studies. crc for sustainable tourism. worboys, s. and gadek, p.a. 2004. rainforest dieback: risks associated with roads and walking track access in the wet tropics world heritage area. rainforest crc. wu, c.h.j. and liang, r.d. 2009. effect of experiential value on customer satisfaction with service encounters in luxury-hotel restaurants. international journal of hospitality management, 28:586593. yoon, y. and uysal, m. 2005. an examination of the effects of motivation and satisfaction on destination loyalty: a structural model. tourism management, 26:45-56. žabkar, v., brenčič, m.m. and dmitrović, t. 2010. modelling perceived quality, visitor satisfaction and behavioural intentions at the destination level. tourism management, 31:537-546. zhang, s. and chan, c.s. 2016. nature-based tourism development in hong kong: importance– performance perceptions of local residents and tourists. tourism management perspectives, 20:3846. 25 64 community and industry attitude towardsusing invasive prosopisjulifloraas a dry matter energy sourcefor small scale industries: a case study in hambantota, sri lanka w.a.r.t.w.bandara* and k.m.e.udadini the department of zoology and environmental management, university of kelaniya, sri lanka date received: 2018-02-09 date accepted: 2018-06-15 abstract bundala is sri lanka’s first ramsar wetland declared under ramsar convention, and it has been declared as a national park in 1993 under fauna and flora protection ordinance.at present, wide spread of p.juliflora in the bundala national park area has become a threat to diverse ecosystems, and the park management is removing substantial biomass of p. juliflora each year in an attempt to control this invasive species. as such, investigating the potential to utilize the removed biomass of p.juliflora has become important. this study was conducted with the objective of evaluating community and industry attitude and awareness of using p.juliflora as a dry matter energy source in hambantota district. two different questionnaires were used for two groups after pre testing in ambalantota, hambantota and tissamaharama divisional secretariat divisions. according to study findings, subsistence energy needs of community are basically fulfilled by common fuel wood species in the area such as manilkarahexandra and drypetessepiara. community in the area is aware about the fast spread of p. juliflora over native species. approximately 45% of study respondents represent brick industry and they often use rice husk ovens due to lack of firewood to be found in the area and the high availability of rice husk. since industry and community prefer p.juliflora as a fuel, responsible agencies should make appropriate arrangements to harvest, process and make available the biomass to partially fulfill the thermal energy requirement in the area. key words: prosopisjuliflora, small scale industries, bundala national park, dry matter energy source 1. introduction mesquite, prosopisjuliflora (fabaceae) which is native to central and northern south america, was first introduced to sri lanka by the royal botanic gardens, peradeniya in 1880. later in early 1950s, it was introduced to hambanthota district in southern province of sri lanka to improve saline soils, and to address soil erosion in the coastal region (algama and seneviratne, 2000, kotagama et al., 2009).since then, p. juliflora has become a very aggressive invasive plant threatening wide ranges of agricultural lands and natural habitats including bundala national park (bnp) in hambanthota district. bundala was designated a national park in 1993 andis the island’s first ramsar wetland. seven terrestrial vegetation/habitat types, namely dry thorny scrubland, arid zone forests, sand dune vegetation, gentle sea shore vegetation, arid zone maritime grasslands/pastures, riverine forest, mesquite scrublands have been identified from bundala national park (bambaradeniya et al., 2002, menr, 2005).die back of manilkarahexandra that forms a single species dominant canopy in tropical semi deciduous forests in bnphas been observed after the invasion of p. juliflora (perera, 2012, gunarathne and perera, 2016). *correspondence:rangika@kln.ac.lk tel: +94 112903486 issn 2235-9370 print/issn 2235-9362 online © university of sri jayewardenepura mailto:rangika@kln.ac.lk daham doi: 10.31357/jtfe.v8i1.3484 bandara and udadini/journal of tropical forestry and environment vol. 8, no. 01 (2018) 64-72 65 the seeds of p. julifloraare dispersed by animals, specifically by cattle and elephants that eat pods (rathnayake, 2014).wide spread of p. juliflora along with other invasive plants such as opuntiaficus has affected the survival of elephants and migratory birds by changing their habitats in the bnp (bambaradeniya et al., 2002). the shade provided by p. julifloracreates a more favourable environment for o. ficus that also has negative impact on wild animals. with deep penetrating roots, p. juliflora can draw water from deeper soil layers and hence affects the ground water table. before this invasion of p. juliflora in bundala national park, over 75% of the beach in hambantota district was covered with spinifexlittoreus together with other native species. the thorny shrub forests in the area are naturally covered entirely with native species such as dichostachyscinerea, flueggealeucopyrus, cassia auriculata, salvadorapersicaand ziziphus spp. aggressive growth of p. julifloraa has resulted in reduction in population density of these native floral species. p.juliflora has invaded the beach near hambantota town and it is spreading towards the bundala national park (algama and seneviratne, 2000). p.juliflora thrives in almost all types of soils under widely varying climatic conditions and set seeds from the second year (silva, no date; mendes, no date).apart from this, a study revealed that presence of fast growing p. juliflora might be the reason for dying back of m. hexandra which is a native and common species to bundala due to efficient drawing of ground water through its extended root systemand creates water scarce situation during dry periods. power generation from vegetation biomass is considered one of the best alternatives to the growing energy demand. recent fluctuations in energy costs and growing attention to greenhouse gas emissions have made vegetation biomass a potentially stable green fuel source that can help displace the demand for fossil fuels and purchased electricity (perera et al., 2010). conversion of vegetation biomass into energy is carbon dioxide neutral. past studies have shown that p.juliflora grown in sri lanka has a high energy potential as it contains high calorific value, high wood density, low moisture content and low ash content comparative to, gliricideasepium, acacia auriculiformis, leucenaleucocephala and eucalyptus grandis; the commonly used fuel wood species in the country (bandara and ranasinghe, 2016).it is b e i n g utilized in industrial sectors for their thermal energy requirements in africa and asia. since p.juliflora has a fast growth rate and an ability to grow in variety of soil conditions, coppicing ability and rapid re-sprouting following harsh and repeated cutting, devoid of showing any harmful effects on plant health this plant can be considered as a favorable fuel wood species (pasieczniketal.,2011). at present, salt industry in hambantota district produces 60% of the total salt production of the country (hambantota district chamber of commerce, 2017). there are over 3,000 familiesin operation engaged in textile weaving, sewing, and tile and brickwork while over 55% of the total population depends on agriculture, especially paddy milling is a major industry in the region(hambantota district chamber of commerce, 2017). further citronella, cinnamon, pepper, fruits such as mango, melon, papaya, citrus, wood apple, pineapple and banana grow well here alongside low country vegetables like beans, tomato, gourd, and pumpkin.coconut and coconut byproducts as copra-mills, coconut oil, coir mills, and distilleriescan be identified as another major source of income. fisheries is a leading industry and also hambantota is reputed for buffalo milk and curd, which also contributes significantly to the regional economy. livestock farming and animal husbandry in cattle, poultry and goats are among other income generating sectors of the community (hambantota district chamber of commerce, 2017). out of 156,476 families live in hambantota district, 93% families rely on fuel wood to fulfill their energy requirement while 0.1% from kerosene, 6.4% lpg, 0.01% from electricity, 0.007 from saw dust/paddy husk and 0.21 from other sources (department of census and statistics, 2017). though p. juliflorais rapidly expanding its range in the bnp affecting biodiversity no attempt has been yet taken either to eradicate or control its range expansion. therefore, t his study was 66 conducted with the primary objective of evaluating community and industry attitude and awareness of using p. juliflora as a dry matter energy source in hambantota district. 2. methodology two different questionnaires were designed to survey the attitudes of the community and industryin usingp. julifloraas a dry matter energy source questionnaires consist of five sections to cover the; community and industry knowledge on different uses of p.juliflora, current energy sources of community and industry, community and industry preference on p.juliflora over other available energy sources and the advantages of using this species as an energy source. questionnaires were designed with structured, scale and open ended questions and they were pre tested with randomly selected 10 university students and 10 academics in the university of kelaniya. questionnaires wereedited to incorporate comments before collection of data. the survey was carried out in thissamaharamaya, ambalantota and hambantota divisional secretariat divisions in hambantotadistrict. thesethree divisional secretariatslie in the boundary of bundala national park (figure 1). figure 1: map of the ambalantota, hambantota, lunugamwehera and tissamaharama divisional secretariat of hambantota district where community and industrial survey was carried out.shaded area represents bundala national park. for the questionnaire survey, a total of 55 industries and 30 households were randomly selected representing three divisional secretariats in the hambanthota district. face to face interviews bandara and udadini/journal of tropical forestry and environment vol. 8, no. 01 (2018) 64-72 67 were carried outusing pre designed and tested questionnaire with the selected respondents.data collected from two different questionnaires were analysed using spss software. descriptive statistics were used to identify frequencies, mean values and respondents’ profile. cluster analysis was performed to identify clusters of respondents to identify the market segment where p.juliflora is readily accepted as a dry matter energy source. 3. results 3.1 respondents profile response rate for both surveys were 100% as respondentswere interviewed face to face by an interviewer.when considering the composition of industries, majority aremediumscale industries (ssi) comprised ofbrick, curd, bakery, salt and a few small scale industries (ssi) such as sweet manufacturing industry in ambalantota, hambantota and thissamaharamaya divisional secretariats. brick, curd and bakery industries were common to all the selected areas while salt and sweet production was confined to hambantota divisional secretariat (figure 2). figure 2: composition of industries participated for the survey in hambantota district. all the respondents from three divisional secretariat prefer m. hexandra (100%) followed by drypetessepiara (80%) as a dry matter energy source to produce thermal energyin their relevant industries.most of the industries in hambanthota (78.7%) and ambalanthota (75%) usedm. hexandra as their main fuel wood while the industries in thissamaharamaya preferred other types of fuel wood species (75%) such as limoniaacidissima, chloroxylonswietenia, azadirachataindica, leucaenaglauca. respondents of industries in all the three divisional secretariatscould identifyp.juliflora. more than 50% of respondents of industries have an understanding on usage ofp.julifloraasas a fuel wood. however, the highest industrial usage of p.juliflora as an energy source was recorded fo rhambantota (57.89%) followed by ambalantota (38.46%) and thissamaharama(26.08%). most of the industries such as curd and sweet could be seen in hambantota divisional secretariat while the industry composition of other two study areas is primarily consist of brick industry with ovens mostly fed by rice husks.respondents of industries had comparatively lower understanding on important energy properties of p. juliflora as a dry matter energy source; high heat capacity, high production of charcoal and ease of ignition. slat, 7.30% backery, 18.20% curd, 20% brick, 45.40% sweet, 9.10% 68 figure 3: percentage of respondents from each divisional secretariat about their level of understanding of fuel wood attributes of p. juliflora. apart from the forest act no.1908 of sri lanka which prohibits extraction of trees from a national park, this study revealed that the practical difficulties experienced by majority of industries in all the three areas of using of p.julifloraas a fuel wood are thorny stems, difficulties in fellingdue tostrong hard core, difficulties in transportation and lack of on time availabilityto meet the existing demand. however, community preference of using p.juliflora species show higher values in all three areas. according to the results, large scale industries in the three selected divisional secretariats, salt and bakery industries, use electricity as their main energy source while small and medium scale industries such as curd, sweet and brick industries use firewood as their main energy source. bakery and curd industries show 100% usage of fire wood in thissamaharama and ambalantota area. therefore, supply of p.juliflora as a fuel wood will be more beneficial for curd and bakery industries which are located in thissamaharama and the ambalantota area. subsequently, of salt industries which use only p.juliflora could be observed in hambanthota area. they use this species in salt drying process and an elevated temperatures could be experienced within the salt drying yardaccording to study 75% respondentsfrom salt processing industries believe that p.juliflora is a superior energy source with its high generating heat capacity and they are very willing to use p.juliflora in their industries as a dry matter energy source if available. majority of sweet(78%) and curd (81%) industries use p.julifloradue to its high heat capacity. both of these industries use p.julifloraalong with m. hexandra and d. sepiara which are abundant in the area. according to the cluster analysis carried out, three industry clusters could be derived based on their primary energy source. 0 10 20 30 40 50 60 70 80 90 100 hambantota ambalantota thissamaharama speices identification different uses practical difficulties identifies as a fuel wood high production of charcoal ease of ignition bandara and udadini/journal of tropical forestry and environment vol. 8, no. 01 (2018) 64-72 69 table 1: identified three clusters of respondent industries based on current primary energy source. cluster1 cluster 2 cluster 3 µ=0.03 µ=0.89 µ=0.07 energy source electricity fuel wood rice husk % of respondents 0.54% 50.9% 43.6% scale large scale small scale small scale typeof industries salt, bakery curd, bakery, sweet, salt brick willingness to use p. juliflora as an energy source 0% 100% 70.9% (if fuel wood ovens are provided) currently use p. juliflora as an energy source 0% 38.1% 0% 3.2 use ofp. juliflora as a household energy source majority of respondents occupied in agriculture related activities.all the respondents use fuel wood as their main energy source for their daily subsistence consumption. about 17% ofrespondents use electricity while 7% use lp gas to fulfill their energy requirements. according to observations villagers can fulfill their fuel wood requirementfrom their own home gardens. hundred percent of respondents use manilkarahexandra ,followed by drypetessepiaria (80.00%), leucaenaglauca (33.3%), gliricidiasepium(16.4%) and other types of trees (43.3%) such as azadirachtaindica, limoniaacidissima and prosopisjuliflora as fuel wood sources for their stoves. majority of respondents (90%) could easily identify p.juliflora species and 93% of respondentswereaware of the usefulness of p.julifloraasas timber and fodder. interestingly, 90% of respondents prefer to use p.julifloraasas an energy source to fulfill their subsistence need (figure 4). figure 4: percentage usage of source of energy by the community in hambantota district. figure 5: percentage of different types of fuel wood species used by the community in hambantota district. people in study area use p.juliflora for co-combustion with other commonly use fuel wood species. however, 60% of respondents in the community were aware about the advantages of using 0.00 20.00 40.00 60.00 80.00 100.00 fuel wood electricity l p gas 0.00 20.00 40.00 60.00 80.00 100.00 70 p.juliflora as an energy source compared to the other common fuel wood species in the area. sixty three percent of respondents had an understanding on high calorific value produced by 1 kg of fuel wood relative to the other common fuel wood species and its ability of continuous burning after ignition. about 61% of respondents believe that about low moisture content of p.juliflora fuel wood increases the efficiency and decreases the time taken for ignition. however, only 13% of respondents were aware of that p.juliflorafuel wood produces less amount of ash which is paramount for a good biomass energy source. study revealed that some percentage of the community use p.julifloraby knowing its advantages as a fuel wood source and some percentage use p.juliflorawithout knowing its advantages as a fuel wood source. out of all the respondents 60% of respondents know that the fuel wood is hard and heavy in weight comparative to the other fuel wood speciesthough they cannot recognize that property as the wood density. figure6: community awareness on certain fuel wood characteristics of p.juliflora. people use to make fences from this plant since the stem is hard and thorny. however, majority of respondents (90%) preferred to use p.juliflora if there is adequate supply. but, community in the surveyed area do not have access right to this species because of the rules and regulations executed by the department of wildlife to avoid entering to the bnp where p. juliflorais highly abundant. further, community has found it difficultto mechanically harvest the tree due to its hard, and thorny multi stems. 4. discussion with growing demand for timber and fuel wood, utilization of alternative timber species have been emphasized in recent research (hoogwijk et al., 2003; mohan et al., 2006; perera et al., 2012; jayawardhane et al., 2016). especially, the possibility of utilizing the biomass of invasive plants such as p. juliflora has been explored in literature (field et al., 2008; oduor and githiomi, 2013). the results of the study reveals the willingness of community in hambathota district to use p. julifloraas an energy source for domestic and industrial purposes. p. juliflora as a dry matter energy source was highly preferred byindustries in ambalantota followed by tissamaharama and hambantota d.s. divisions. brick and bakery industries were mostly found in ambalantota and tissamaharama d.s. divisions and they prefer to use p.julifloraas a primary energy source in their industries. respondents who use chaff or rice husks ovens were also preferred touse p.juliflora as a fuel source if they are provided with fuel wood ovens for brick manufacturing. according to the brick stove owners, there are certain advantages of having fuel wood ovens over rice husk ovens in brick manufacturing. bricks from fuel wood ovens are higher in mechanical properties including water resistance capacity, 0 20 40 60 80 100 high calorific value high wood density low ash content less ignition time bandara and udadini/journal of tropical forestry and environment vol. 8, no. 01 (2018) 64-72 71 durabilityand production time than rice husk ovens. lack of continuous supply and relatively high cost of fuel wood are the main reasons for using rice husk ovens. small scale industries in the study area utilize 750-1500 kg of fuel wood per weekon average. if this species is given to the small scale industries with a proper management system, it would be an economically and environmentally feasible option for industries in hambantota district. it is recommended to carry out a feasibility study to supply p.juliflora as a dry matter energy source for small scale industries in ambalantota, tissamaharama and hambantota areas. at the same time fast spread of invasive p.juliflora can be controlled in a sustainable manner. 5. conclusion prosopisjuliflora is a fast growing tree species that can be seen in hambantota district, sri lanka and it has invadedinto important ecosystems in the area including bundala national park. periphery of the bundala national park is already dominated by p.juliflora along with cactus and this spread inhibits the growth of other plant species native to the area. community in the area is aware about the fast spread of p. juliflora over native species even though they are not aware of the scientific means of invasion.according to study findings, subsistence energy needs of the community is basically fulfilled by different fuel wood species, manilkarahexandra and drypetessepiara, which are available in the area but legally restricted in felling. utilization of ipilipil, gliricideasepium and other fuel wood species common to the country are significantly low. brick industry in hambantota district often use rice husk ovens instead of fuel wood ovens and the main reason for that is the lack of adequate and continuous supply of firewood in the area and the abundant of rice husk as main livelihood of the people is agriculture. community and the small scale industry in the region are willing to use p. juliflora as a dry matter energy source to fulfill their energy needs if the fuel wood is readily available for them. recommendation since industry and community are very much interested in using p.juliflora as a fuel wood species responsible agencies should make proper arrangements to harvest, process and make available the species as a dry matter energy source to partially fulfill the energy requirement in the region.for this, collaboration of responsible agencies, the wildlife department, timber cooperation, sustainable energy authority and ministry of mahaweli development and environment is needed. similarly cutting down of native plant species for fuel wood such as manilkarahexandra and drypetessepiaria can be minimized if this species is promoted as an alternative fuel wood. references algama a., seneviratneg.i., 2000. nature of the invasive species prosopisjuliflora in sri lanka, sri lanka, ministry of forestry and environment and national agricultural society of sri lanka. bambaradeniya, c.n.b., ekanayake, s.p., fernando r.h.s.s., w.p.n. perera. r.somaweera r., 2002. a biodiversity status profile of bundala national park a ramsar wetland in sri lanka. iucn, sri lanka, isbn: 955-8177-16-4pp bandara w.a.r.t.w., ranasighe o.r., 2015. comparison of energy potential of prosopisjuliflora with commonly used fuel wood species, leucaenaleucocephala in sri lanka, air that we breathe 2016: sixth national symposium on air resource management in sri lanka, air resource management centre (airmac), ministry of mahaweli development. & environment. cronk, q. c. b., j.l. fuller., 1995. plant invaders: the threats to natural ecosystems. chapman and hall, 486. department of census and statistics, 2017. www.statistics.gov.lk/pophousat/cph2011/index.php?filename=h2&gp=activities&tpl=3, accesed on december, 2017. 72 field, c. b., campbell, j. e., &lobell, d. b. (2008). biomass energy: the scale of the potential resource. trends in ecology & evolution, 23(2), 65-72. gunarathne r.m.u.k and perera d., 2016, does the invasion of prosopisjuliflora cause the die -back of the native manilkarahexandra in seasonally dry tropical forests of sri lanka, tropical ecology, 57 (3): 475-488. hambantota district chamber of commerce, www.hdcc.lk/, accesed on december, 2017. hoogwijk, m., faaij, a., van den broek, r., berndes, g., gielen, d., &turkenburg, w. (2003). exploration of the ranges of the global potential of biomass for energy. biomass and bioenergy, 25(2), 119-133. jayawardhane, j. k. p. c., perera, p. k. p., lokupitiya, r. s., amarasekara, h. s., &ruwanpathirana, n. (2016). the effect of quality attributes in determination of price for plantation-grown teak (tectonagrandis) logs in sri lanka. annals of forest research, 59(1), 105. joshi, a. a., d. mudappa, t. r. s. raman., 2015. invasive alien species in relation to edges and forest structure in tropical rain forest fragments of the western ghats. tropical ecology, 56: 233-244. kotagama s.w., perera n. sunandalal k.d. 2009. policy interventions for managing ias within protected area systems of sri lanka -a case study from bundala national park, national symposium on invasive alien species,21-22 may,browns beach hotel, negombo, sri lanka. kotagama, s., perea, n., &k.d.sundalal. (2009). policy interventions for managing ias within protected area systems of sri lanka-a case study from bundala national park. national symposium on invasive alien species, 27. levine, j. m., m. vilà, c. m. d’antonio, j. s. dukes, k. grigulis& s. lavorel. 2003. mechanisms underlying the impacts of exotic plant invasions. proceedings of the royal society b: biological sciences, 270: 775-781. menr.2005. habitat maps for selected areasin sri lanka: bundalanationalpark. finalreportpreparedbyemlconsultants. ministry of environment & natural resources. colombo. 104 pp. mohan, d., pittman, c. u., & steele, p. h. (2006). pyrolysis of wood/biomass for bio -oil: a critical review. energy & fuels, 20(3), 848-889. oduor, n. m., &githiomi, j. k. (2013). fuel-wood energy properties of prosopisjuliflora and prosopispallida grown in baringo district, kenya. african journal of agricultural research, 8(21), 2476-2481. pasiecznik, n., &weerawardane, n. (2011). invasion of the exotic tree species prosopisjuliflora in puttalam district-its spread,new records and the need for action. the sri lanka forester, 33. perera, p. k. p., amarasekera, h. s., &weerawardena, n. d. r. (2012). effect of growth rate on wood specific gravity of three alternative timber species in sri lanka&59; swieteniamacrophylla, khayasenegalensis and paulownia fortunei. journal of tropical forestry and environment, 2(1), 26-35. perera, r., perera, p., vlosky, r.p., & darby, p. (2010). potential of using poultry litter as a feedstock for energy production. working paper no. 88, louisiana forest products development center, louisiana state university agricultural center, baton rouge, louisiana. ratnayake, h.d., samarakoon, s.p.a.g.v. &karunaratne, y.g.p., (2003). case study on community participation in the management and conservation of the bundala national park. journal of the national science foundation of sri lanka. 31(1-2), pp.73–78. doi: http://doi.org/10.4038/jnsfsr.v31i1-2.3024 sudesh, a. 2013. looming threat of lantana (lantana camara l.) on biodiversity. sri lankan wildlife, 115-116. yakandawala d., yakandawala k. 2011. hybridisation between native and invasive alien plants: an overlooked threat to the biodiversity of sri lanka, ceylon journal of science 40. http://doi.org/10.4038/jnsfsr.v31i1-2.3024 microsoft word 4 hettiarachchi dissanayake & hettiarachchi /journal of tropical forestry and environment vol. 3, no. 01 (2013) 24-36 24 floristic composition of home-garden systems in dumbara (knuckles) conservation area with an emphasis on endemic species d. m. a. j. dissanayake and p. l. hettiarachchi * faculty of applied sciences, rajarata university of sri lanka date received: 24-11-2012 date accepted: 18-02-2013 abstract home gardens are multistoried ecosystems and are important not only for in-situ biodiversity conservation, but also as valuable food sources, fodder, medicine and spices. the main objective of this study was to make decisions about the variations of home garden composition and to identify the endemic species. fifty five home gardens were studied in northern flank from january to april 2012. two large (10x10m 2 ) and four small (1x1m 2 ) quadrates were studied in each home garden. individuals ≥ 1.5 m height and ≥ 1 cm dbh were measured to calculate ivi. species identification was done on site and further at the national herbarium, peradeniya. total of 1335 individual woody-perennials and 4603 herbs were found in 11,000 m 2 of study area. one hundred and fifty two woody-perennial species (19 endemic, 44 naturalized exotics, 37 cultivated and 52 timber) under 54 families and 56 herb species (46 medicinal) belonging to 33 families were recorded. euphorbiaceae was the dominant family with 15 species, followed by fabaceae (11 species), anacardiaceae (10 species), rutaceae (10 species), myrtaceae (7 species), rubiaceae (6 species), arecaceae (6 species), moraceae (5 species), sapindaceae (4 species) and zingiberaceae (4 species). highest number of plant families (43) was recorded in pitawala, while the lowest number of plant families was recorded in polommana (24). based on the importance value index (ivi), the species to pay highest priority for conservation were selected. according to shannon diversity values for different villages, rathninda is the most stable and less disturbed, whereas polommana is the most unstable and highly disturbed village. there were five endemic anacardiaceae species (campnosperma zeylanicum, mangifera zeylanica, semecarpus coriaceae, semecarpus nigro-viridis, semecarpus walkeri). twelve percent of the studied population were interested in timber trees such as tectona grandis, melia azedarach, swietenia macrophylla and chloroxylon swietenia. twelve percent of the studied population preferred fruit trees while 5% were interested in some medicinal plants. preference of this nature indicates that in the future, the plant diversity in these home gardens is likely to decline considerably. this might even lead to the extinction of rare, endemic plant species. therefore, people in northern flank encouraged to incorporate multipurpose endemic plants and plants with less ivi values in their home gardens in order to maintain high diversity and to conserve endemic and relatively rare plants while gaining substantial income through their home gardens. keywords: northern flank, home gardens, conservation, woody-perennials, endemic species 1. introduction tropical home gardens are generally regarded as sustainable production systems (abdoellah et al. 2001). a home garden is a clearly bounded piece of land cultivated with a diverse mixture of annual and perennial crops, and on which a house is built (karyono, 1990). the major function of home gardens especially in rural areas, are subsistence production and income generation (soemarwoto and conway, 1992). because of the high biodiversity existing in home gardens, a wide spectrum of multiple-use products can be generated with relatively low labour, cash or other inputs (christanty, 1990). *correspondence: phlakshmi@yahoo.com tel: +94712448139, +94771238980 issn 2235-9370 print / issn 2235-9362 online ©2013 university of sri jayewardenepura dissanayake & hettiarachchi /journal of tropical forestry and environment vol. 3, no. 01 (2013) 27-39 25 in times or seasons of scarcity, home gardens with their diverse products available year-round, contribute to food security. they also fulfil many social, cultural and ecological functions (abdoellah et al., 2001). the multi-layered, forest-like vegetation structure of home gardens contributes substantially to the sustainability of this production system. among others, this structure can protect the soil from erosion, offers a habitat to wild plants and animals, promotes a favourable microclimate and makes efficient use of light, water and other resources (christanty et al., 1986). because of their large crop species and varietal diversity, home gardens are regarded as an ideal production system for in situ conservation of genetic resources (watson and eyzaguirre, 2002). however garden diversity varies according to ecological or socio-economic factors or characteristics of gardens or gardeners (christanty et al., 1986). home gardens particularly preserve much of the cultural history, as they are the sites where many useful plant species have been subjected to intense management regimes over extended periods. through many years, farmers have cultivated and selected the plant species they desired, and in this way, home gardens are reservoirs of current and potential resources as well as a crucial site of selection and domestication of some plant species (hawks, 1983) plant composition in home gardens is possibly influenced by factors like: access to water, economic activities of owners and availability of labour, traditional social organization, modernization processes and economic development (rico-grey et al., 1990). using multivariate statistical techniques, researchers have found that floristic composition of home gardens was relatively similar within villages, but varied among regions. the home gardeners are perpetual experimenters, and they are constantly trying and testing new species, varieties and management over the centuries they have selected specific species and manipulated their physical and ecological locations, planting for maximising space and production. from the ground layer to upper canopy, the gradient of light and humidity determine different niches that species exploit according to their own requirements (fernandes and nair, 1986). therefore study of these parameters gives an idea of the temporal and spatial positioning of plants, species interaction and mixed species silviculture that are pertinent for designing multistate agro forestry and for the management of its productivity (gillespie et al., 1993). dumbara range is very important in terms of its hydrological wealth as the catchment of sri lanka’s longest river, the mahaweli. the range is endowed with many different forest types. a total of 1033 flowering plants belonging to 141 families have been recorded from the diversified vegetation types in dumbara. among them, 255 (25%) are tree species, while the balance consists of shrubs or herbs , of the total number of flowering plant species documented in dumbara, 15% are endemic to sri lanka, while about 3% are nationally threatened. although the dumbara area covers less than 0.5% of the land in the country, it contains almost one third of the island’s flowering plant species (diversity of woody plants in the dumbara forest, environment management division forest department, 2005). home gardens similar to natural forests are found around the homesteads of dumbara area. a well-developed multi-storey home garden generally includes a canopy (20 m), sub canopy (10 m) and shrub/ herb layer. home gardens are also important faunal habitats that provide animals with feeding and nesting grounds. there are around 80 villages in and around the dumbara forest region which form a unique bio cultural landscape. even in this sophisticated era, life in these villages exhibit the simple harmonious co-existence of man and nature. information on the studies carried out in home garden in the northern flank of dumbara is scares. this study was carried out in some peripheral villages of the northern flank of dumbara home gardens to examine component interactions and productivity in the home gardens. information on only two related studies namely “conservation implications of home garden agro-forestry systems”, and “livelihood development” carried out by dgapik abeywardana, (university of peradeniya) in 2008 is available. however, those only provide information on 3 villages; kalugala, kosdanda and udailluka in dumbara south-eastern flank. hence, this study is important to compare the results of dissanayake & hettiarachchi /journal of tropical forestry and environment vol. 3, no. 01 (2013) 24-36 26 above two flanks and to make decisions about the variations of home garden composition in dumbara. this study was designed to accomplish following objectives; • to identify floristic composition of home garden systems in some peripheral villages of dumbara (knuckles) conservation area. • to identify the endemics, naturalized exotics and timber trees in the study area • to identify plant species and highly disturbed villages for conservation 2. methodology 2.1 study area dumbara conservation forest nestles within the dumbara mountain range – sri lanka’s misty mountains. located at latitudes 70 5’n and longitudes 810’ e and covering 180 km 2 , its situated at the boundary of the wet and dry zones. the study area of the research lies in several peripheral villages of the knuckles conservation area, located in matale district. geographical coordinates are 7° 17' to 7° 40' north and 80° 43' to 80° 55' east. this covers areas including human habitations, well wooded home gardens, paddy fields and forest patches. the study area is situated within the wet zone of sri lanka. figure 1: detailed map of the study site to conduct the study, six villages (pitawala, polommana, atanwala, rathninda, mahala kotuwa and illukkumbura) from the northern flank (within matale district) of dumbara conservation area were selected in january 2012 considering some factors such as elevation and distance from the existing natural or semi-natural forests. five (5) home gardens from polommana village (because there were only five homes) and ten (10) home gardens from other 5 villages were selected. to study the structure and composition of the home garden vegetation, the following methods were applied: a.) woody vegetation: two large (10 m x10 m) quadrates were studied from each home garden selected. all the individuals above 1.5 m height and above 1 cm dbh were identified into species level, counted and recorded the number of individuals, dbh and height were measured. to quantify and compare the species dominance within home gardens in each village, density, frequency, dominance, basal area and importance value index (ivi) were calculated for the species. b.) herbaceous (ground layer) vegetation: two small (1 m x1 m) quadrates were studied from each large quadrate selected (four quadrates for each home garden). all individuals were identified into their species level, counted and recorded. dissanayake & hettiarachchi /journal of tropical forestry and environment vol. 3, no. 01 (2013) 27-39 27 3.2 identification of plant species onsite identification was done for the common species using the expert and indigenous knowledge. they were identified up to species level using the checklist. determination of other species was done with the help of national herbarium, peradeniya. structured and informal interviews were conducted when necessary (depending on the literacy level of the household). additionally, the traditional practices and rituals related to forest-home garden activities and use of indigenous knowledge on wellbeing of the system were taken into surveying. 2.3 data analysis 1. shannon-weiner index: species diversity of the plants recorded in quadrates was analyzed with the use of shannon-weiner index. h = -∑i=1 (pi) (log pi) h= shannonweiner index s= number of species pi = population of total sample belonging to the i th species 2. density, frequency and dominance were calculated for ivi (importance value index) 3. bio-diversity professional version 2.0 was used to analyse distribution, simpson diversity index and margalef diversity index. 3.4. data analyzing techniques abundance relative frequency = number of sample plots with a sighting of a species total number of sample plots ×100 relative density = !"#$% &' ()*(+(*!,-. &' , ./$0($. !"#$% &' .,"/-$ /-&1. 2(13 , .(431()4 &' , ./$0($. × sample plot area ∑7 89:;<= >? @ab@c@b9def >? d fg<h@<f 89:;<= >? fd:ge< ge>if j@ik d f@lki@al >? d fg<h@<fm ×100 relative abundance = relative frequency + relative density importance value index (ivi) a measure often used to describe and compare the species dominance of the plots is the importance value index of cottam and curtis (1956). the ivi for a species is calculated as the sum of its relative dominance, its relative frequency and its relative density. certain points have to be acknowledged, to understand the arguments the ivi is providing. also some species may be dominant in one site but do not occur in the other sites. therefore their local dominance is not displayed in the overall statistics. still, the ivi is giving a figure with the overall importance of a species. relative frequency 2 = number of individuals of a species total number of species ×100 relative dominance 2 = total basal area of a species total basal area for all species ×100 relative density 2 = number of individuals of a species total number of individuals × 100 ivi = relative frequency 2 + relative dominance 2 + relative density 2 dissanayake & hettiarachchi /journal of tropical forestry and environment vol. 3, no. 01 (2013) 24-36 28 3. results and discussion a total of 1335 trees and 4603 herbs were recorded in 11000 m 2 (1.1 ha) in six peripheral villages (55 home gardens) in dumbara region. hundred and fifty two plant species (19 endemic species, 44 naturalized exotics, 37 species only under cultivation and 52 timber species) under 54 families and 56 herb species (46 medicinal) belonging to 33 families were recorded. euphorbiaceae was the dominant family having 15 species, followed by fabaceae (11 species), anacardiaceae (10 species), rutaceae (10 species), myrtaceae (7 species), rubiaceae (6 species), arecaceae (6 species), moraceae (5 species), sapindaceae (4 species) and zingiberaceae (4 species). the remaining families contained 1 to 3 species. anacardiaceae, arecaceae, cariaceae, commelinaceae, euphorbiaceae, fabaceae, lauraceae, meliaceae, moraceae, moringaceae, musaceae, rubiaceae, rutaceae, sabiaceae, sapindaceae and sterculiaceae were present in all villages. highest number of plant families (43) was recorded in pitawala, while the lowest number of plant families was recorded in polommana (table 1). asteraceae, boraginaceae, ebanaceae, malvaceae, punicaceae, theaceae and thymelaceae were only recorded in rathninda sites. plant species in debrageaceae, lecythidaceae and melastomataceae were recorded only in pitawala home gardens. table 1: number of plant families in each study site village no. of plant families pitawala 43 polommana 24 atanwala 26 rathninda 42 mahala kotuwa 34 illukkumbura 31 3.1. endemic plants, naturalized exotics and timber trees in the study area among the 152 plant species, 19 were endemics (12.5 %). there were 5 endemic plant species; campnosperma zeylanicum, mangifera zeylanica, semecarpus coriaceae, semecarpus nigro-viridis, semecarpus walkeri in family anacardiaceae. other endemic species were callophyllum trapezifolium, garcinia quaesita (clusiaceae); diptocarpus zeylanicus, shorea hulanidda (dipterocarpaceae); agrostistachys hookeri, phyllanthus myrtifolius (euphorbiaceae); aidia gardneri, diplospera erythrospora (rubiaceae); strobilanthes anceps (acanthaceae); canarium zeylanicum (burseraceae); diospyros oppositifolia (ebanaceae); scolopia crassipes (flacourtiaceae) and pandanus ceylanicus (pandanaceae). out of the forty four naturalized exotics (28.9%) found, 5 species name;ly codiaeum variegatum, jatropha curcas, manihot esculenta, phyllanthus acidus and ricinus communis were in family euphorbiaceae. there were 4 from each fabaceae and rutaceae. several other families contained 1 to 3 naturalized exotics. these species are utilized by the home gardeners for various purposes such as fruit, timber, medicine and as fence trees. thirty seven species (23.0%) out of which 5 species were in family rutaceae were found only under cultivation in these six villages. fifty two species (34.2%) recorded are used for timber purposes. they are in combretaceae and sapindaceae. the major threat is that most endemic plant species such as campnosperma ceylanicum, mangifera zeylanica, garcinia quaesita, diptocarpus zeylanicus, shorea hulanidda, diospyros oppositifolia and gardonia speciosa are fell for timber. dissanayake & hettiarachchi /journal of tropical forestry and environment vol. 3, no. 01 (2013) 27-39 29 3.2. comparison of endemic species, naturalized exotics and trees only under cultivation in each village most of the endemic species (17), naturalized exotic species (44), species found only under cultivation (33) were recorded in rathninda when comparing with other villages. the lowest number of endemics (6) was recorded in atanwala (figure 2). the number of plant families and the number of plant species recorded in polommana were comparatively low. this may be because there were only 5 home gardens for the entire village. other families had left this village in 10 to 15 years ago due to poor access to the home and lack of various other facilities. therefore, those home gardens (without the home) are now added to the forest boundary and controlled by the forest department. highest number of plant species was recorded in rathninda while the lowest number of plant species in polommana (figure 2). figure 2: number of plant species, endemic, naturalized exotic and timber plant species in studied villages 3.3. dbh variations of plants in study sites all villages are rich with the plants in lowest dbh range (1-50 cm). individuals in this range in all villages, are more than twice in number, to the 50-100 cm dbh range (figure3). plants in 151-200 cm dbh range were not observed in polommana and atanwala (figure.3). this may be due to the fact that villagers have used the trees with higher dbh for their timber purposes. moreover, it should be noted that the dbh also vary depending on the plant species. highest number of plant individuals (9 individuals) in both 101-150 cm dbh and 151-200 cm dbh (7 individuals) was recorded in pitawala. there were more than two hundred plant individuals in rathninda and mahala kotuwa belonging to 1-50 cm dbh range (figure 3). 3.4. height variation of the plant individuals in the study area most of the plants in studied villages were less than 10 m in height. there were 21 individuals in 11-15 m range in pitawala. individuals taller than 15m were not observed in polommana and rathninda (figure 4). n o . o f in d iv id u a ls dissanayake & hettiarachchi /journal of tropical forestry and environment vol. 3, no. 01 (2013) 24-36 30 figure 3: number of individual plants in each dbh class in all village 3.5. density the total tree density of pitawala, polommana, atanwala, rathninda, mahalakotuwa and illukkumbura were 1195, 870, 1160, 1310, 1410 and 1240 ha -1 respectively. species were classified into 5 density classes, e to a; where species that belongs to class e have lowest density while those in a have highest density. the intermediates were also assigned accordingly. species that belonged to density class e need more attention with respect to conservation. acronychia pedunculata, adenanthera pavonina, annona muricata, bambusa vulgaris, callophyllum trapezifolium, capparis zeylanica, clausena dentata, semecarpus coriaceae, shorea hulanidda and terminalia bellirica in pitawala; azadirachta indica, chrysophyllum lanceolatum, ficus benghalensis, melia azedarach and syzygium malaccensis in polommana; ardisia missionis, cordia aubletii, madhuca longifolia, mangifera zeylanica and trema orientalis in atanwala; anacardium occidentale, campnosperma ceylanicum, capparis zeylanica, diospyros oppositifolia and terminalia chebula in rathninda; asystasia variabills, berrya cordifolia, nephelium lappaceum, phyllanthus acidus, schleichera oleosa and terminalia bellirica in mahala kotuwa; azadirachta indica, codiaeum variegatum, ficus benghalensis, jatropha curcas, munronia pinnata, pandanus ceylanicus, semecarpus nigro-viridis and terminalia arjuna in illukkumbura were in density class e (5-10 density ha -1 ). on the other hand abundant species in the villages were artocarpus heterophyllus, coffea arabica, gliricidia sepium, mangifera indica in pitawala; meliosma pinnata, cocos nucifera in polommana; dimocarpus longan, gliricidia sepium in atanwala; pavetta indica, gliricidia sepium in rathninda, tectona grandis in mahalakotuwa, artocarpus heterophyllus and mangifera indica in illukkumbura. one species in mahalakotuwa home gardens tectona grandis belonged to frequency class a (81-100%). however species belonging to frequency class b (61-80%) were absent in those villages. mangifera indica, gliricidia sepium in pitawala; cocos nucifera, meliosma pinnata, cinnamomum verum in polommana; areca catechu, dimocarpus longan, gliricidia sepium, pavetta indica in n o . o f in d iv id u a ls dissanayake & hettiarachchi /journal of tropical forestry and environment vol. 3, no. 01 (2013) 27-39 31 atanwala; pavetta indica, gliricidia sepium, cocos nucifera in rathninda; pavetta indica, gliricidia sepium, dimocarpus longan, cocos nucifera, citrus sinensis in mahalakotuwa; tectona grandis, mangifera indica, gliricidia sepium, artocarpus heterophyllus in illukkumbura belonged to frequency class c (41-60%). figure 4: number of individuals in each height class the frequency gives an approximate indication of the homogeneity of a stand. previous studies have pointed out that high values in higher frequency classes (frequency classes a and b in this case) and low values in lower frequency classes indicate constant or similar species composition while high values in lower frequency classes and low values in higher frequency classes on the other hand indicate a high degree of floristic heterogeneity(give reference). in the present study, high values were obtained in lower frequency classes whereas low values were obtained in higher frequency classes. therefore, according to the above interpretation, it is possible to conclude that there exists a high degree of floristic heterogeneity in each village in the study area. 3.6 basal area and dominance total basal areas in pitawala, polommana, atanwala, rathninda, mahalakotuwa and illukkumbura were about 16226.04, 7961.07, 13189.89, 12159.55, 10255.18 and 7647.13 cm 2 ha -1 , respectively. the highest basal area was recorded in fewer large size individuals; dbh 162 cm (artocarpus heterophyllus),145 cm (mangifera indica), 122 cm (mangifera zeylanica) in pitawala; 158 cm (artocarpus heterophyllus), 149 cm (mangifera indica) in polommana; 158 (ficus hispida), 132 cm (mangifera indica) in atanwala; 128 cm (artocarpus heterophyllus), 105 cm (artocarpus nobilis) in rathninda; 108 cm (artocarpus heterophyllus) in mahalakotuwa and 89 cm (terminalia arjuna) in illukkumbura. the highest contribution to their total basal area was by those individual trees that attain greater than 100 cm dbh for many species. n o . o f in d iv id u a ls dissanayake & hettiarachchi /journal of tropical forestry and environment vol. 3, no. 01 (2013) 24-36 32 basal area provides a better measure of the relative importance of the species than simple stem count (cain and castro 1959, cited in tamirat bekele, 1994). therefore, species with the largest contribution in basal area can be considered as the most important woody species in the forest. high density and high frequency indicates regular horizontal distribution in the forest. high density, low frequency and low dominance are typical for understory species that occur in clusters. some tree species with low density, low frequency and low dominance are the threaten species in the area. 3.7 importance value index to analyse ivi, all species encountered in all villages were grouped into five ivi classes based on their total ivi values. those species, which receive lowest ivi value, were grouped into the fifth ivi class whereas those species with highest ivi value were put under the first ivi class. those species, which were grouped in the fifth ivi class needs highest consideration for conservation while those grouped in the first ivi class, need monitoring and management. based on the ivi output, the following species accorded the highest priority for conservation efforts: osbeckia aspera (1.02), acronychia pedunculata (1.12), murraya exotica (1.16), bambusa vulgaris(1.20), clausena dentata(1.25)in pitawala; phyllanthus indicus (2.66), manihot esculenta (2.66), bambusa vulgaris (2.84), annona glabra(3.05), moringa oleifera(3.14) in polommana; alstonia scholaris (1.07), citrus grandis (1.21), melia azedarach(1.29), cordia monocica (1.42), syzygium assimile (1.42) in atanwala. hibiscus rosa-sinensis (0.86), phyllanthus reticulates (0.87), manihot esculenta(0.90), melia azedarach(0.93) in rathninda; solanum violaceum ortega (0.95), phyllanthus emblica (0.97), phyllanthus acidus (0.99), citrus reticulate (1.02), bambusa vulgaris (1.05) in mahala kotuwa; pandanus ceylanicus (1.11), anacardium occidentale (1.18), phyllanthus emblica (1.25), codiaeum variegatum (1.72), flacourtia indica (1.72) in illukkumbura. the importance value index is imperative to compare the ecological significance of species (lamprecht, 1989). it indicates the extent of dominance of a species in the structure of a forest stand (curtis and mcintosh, 1951). it is stated that species with the greatest importance value are the leading dominants of the forest. 3.8 diversity indices if shannon diversity index value lies between 1.5 and 3.5, it is considered as a less disturbed habitat. when this index value reaches 3.5, the habitat is more stable. according to the shannon diversity values of these study sites; rathninda (1.85) is the most stable less disturbed habitat when compared with the others. polommana (1.51) seemed to be the most disturbed and unstable habitat (table 2). the increased value for margalef diversity indicates the high biodiversity. this is a comparative measure with other sites. in this case pitawala (16.069) has the highest diversity while polommana (8.733) has the lowest (table 2). if simpson biodiversity index is less than 0.5; species are more equitable. here all the values are around 1.0, and hence species are heterogeneous. 3.9 composition of herbs in the study area fabaceae was the leading family for herbs including seven plant species. asteraceae and poaceae contained four species in each, in rubiaceae there were 3 species. remaining families contained 1 to 2 species (appendix i). lamiaceae is the dominating plant family in the study area counting 797 individuals. nevertheless there were only two species in this family, ocimum tenuiflorum and plectranthus zatarhendi (appendix i). in number; 2588 plant individuals were found in pitawala (56.22% of total individuals); all the recorded families except anacardiaceae and menispermaceae were present in pitawala (93.93%). dissanayake & hettiarachchi /journal of tropical forestry and environment vol. 3, no. 01 (2013) 27-39 33 table 2: diversity indices for plant species (excluding herbs) in all study sites village no. of species no. of individu als margalef diversity menhink diversity shannon diversity brillouin diversity evenness base 10 base 2 base 10 base 2 simpson diversity inverse simpson dominance shannon diversity pitawala 25 578 3.774 1.04 1.26 4.18 1.22 4.05 0.972 0.591 0.901 polommana 23 318 3.818 1.29 1.19 3.94 1.13 3.74 0.956 0.487 0.87 atanwala 21 381 3.365 1.08 1.04 3.31 1 3.31 0.896 0.312 0.789 rathninda 31 560 4.741 1.31 1.33 4.41 1.28 4.24 0.971 0.518 0.889 mahala kotuwa 29 427 4.623 1.40 1.32 4.4 1.27 4.21 0.979 0.618 0.905 illukkumbura 22 356 3.575 1.17 1.2 3.99 1.15 3.82 0.965 0.559 0.895 a shannon index for any of the village does not lie between the ranges of 1.5 3.5. so, herbaceous layer in each study site is disturbed and less stable. margalef diversity value is higher in rathninda village (4.741), followed by mahalakotuwa (4.623). less diversity of the herb species in ground layer is shown in atanwala. simpson diversity values in all villages are more than 0.5. as such, species in all villages are heterogeneous (table 3). table 3. diversity indices for herbaceous layer in each study site 3.10 villagers’ income through their home garden products people in polommana receive higher income through their home garden because they have no other option to increase their economy other than cultivating crops. though they are far away from accessible facilities they grow crops in large areas to have their income. there was no statistically significant relationship between the level of economy and the composition of plant species in the home garden (chi-square = 13.308 a , p = 0.102). 3.11 expected other plants preference of villagers regarding what to grow in their home gardens varies from family to family. most prefer cocos nucifera (57%) due to increasing price of coconut. twenty four percent of people expressed an interest in growing timber trees as tectona grandis, melia azedarach, swietenia macrophylla and chloroxylon swietenia. twelve percent preferred fruit trees, 5% requested for medicinal plants such as azadirachta indica, munronia pinnat and cannabis sativa. these expectations indicate that in the near future, only few plant species will be grown in these home village no. of species no. of individuals margalef diversity menhink diversity shannon diversity evenness base 10 base 2 simpson diversity inverse simpson dominance shannon diversity pitawala 89 239 16.069 5.757 1.79 5.93 0.988 0.366 0.916 polommana 40 87 8.733 4.288 1.51 5 0.987 0.516 0.94 atanwala 72 230 13.056 4.748 1.71 5.69 0.988 0.443 0.922 rathninda 97 259 17.276 6.027 1.85 6.13 0.992 0.439 0.929 mahala kotuwa 76 272 13.379 4.608 1.71 5.69 0.988 0.45 0.911 illuk-kumbura 64 248 11.427 4.064 1.66 5.52 0.987 0.475 0.92 dissanayake & hettiarachchi /journal of tropical forestry and environment vol. 3, no. 01 (2013) 24-36 34 gardens (figure 5). consequently, the biodiversity will be greatly reduced and might even lead to the extinction of rare, endangered species. 3.12 plant diseases and home garden management plant diseases such as fungal attacks in bark, insect attacks in coconut bark, iron deficiencies, harms of vegetable caterpillar, insect damages in leaves and parasitic plants were observed in home gardens. plant management can be different in each home garden and the amount of planting in a garden is often difficult to evaluate. plant management in home gardens was categorized into three main groups: cultivated, protected or spared. 1. when plants are said to be cultivated, they are sown or planted by the owner. 2. plants are categorised as protected or encouraged when they are transplanted from other zones outside the garden or when they grow spontaneously in the garden. the owner decides to protect or encourage the plant, for example, by supporting it or attaching the plant to a solid structure, or by putting stones around the plant. 3. spared plants are plants that spontaneously grow in the garden and are not removed. either the farmer knows that the plant does not harm any other plant in the garden, or that it has a specific use. also trees for shade or the edible species are spared. these plants belonged to the original vegetation before the farmers settled in and were not removed when the house was built or when the home garden was established. 3.13 villagers’ attitudes and contribution towards the biodiversity conservation through their home garden seventy two percent of people in all villages knew that by improving the plant composition in their home garden, they can contribute to protect the biodiversity. they were aware of the fact that the richness of plant composition in home garden will lead to the improvement of human beings as well as the protection of the dumbara forest. however the important thing to be pointed out is that 23% of people didn’t know that they can conserve biodiversity through the home gardens. so to have a better world in the future, for their children and for future generations, they should be encouraged to conserve biodiversity in their home. another point is that if the biodiversity is maintained at a high level, species extinction will be low. this will benefit everyone. the majority of the people were aware that the conservation can be done not only in the forests but also in their home gardens. to conserve the biodiversity, women have started to plant various wild varieties of crops in their home gardens. women can be encouraged to grow a variety of species to obtain cut flowers. they can make an income out of it. figure 5. preference of home gardeners for various categories of plants dissanayake & hettiarachchi /journal of tropical forestry and environment vol. 3, no. 01 (2013) 27-39 35 people of the bordering villages are well aware of the importance of the dumbara forest. so, they inform relevant authorities if a stranger tries to enter into the forest. they don’t complain about the people that go to get medicine and poles to make utensils. according to females of the bordering villages, they do not cut down trees or kill animals, not only in the forest but also in their home gardens. educating people, mainly the younger generation about the importance of the biodiversity and the dumbara is done mainly by the females/mothers. they fulfil the task by giving the traditional knowledge and the cultural values to the future generations. the isolation of the region, its frontier character, and the rapid changes that are occurring, in terms of population growth, legal state of land, and political boundaries, make socio-economic data scares and unreliable. the clandestine nature of many activities in the area and the uncertain legality of others make it difficult to get honest responses from local people or government officials about local activities. biodiversity loss of the dumbara forest is resulting due to at least two proximate causes: the habitat loss and the extraction of flora and fauna. the direct or indirect cause for the habitat fragmentation in the dumbara forest was clearing for agriculture in the past. poverty is prominent in the bordering villages of dumbara forest. cash is earned by selling agricultural products which provides the main source of income for the bordering villagers and from day labour. agriculture, in the study area remains small-scale as a result of ecological limitations such as shortage of water during the year and unpredicted weather patterns as well as economical limitations such as lack of proper market value. due to the increasing population, encroachment can be seen. hunting is another threat to the biodiversity of dumbara forest. hunting is carried out by man in the farm plots to protect their crops from wild boars and spotted deer. even though the hunting is illegal these people have no other option. according to gathered information giant-squirrels have become a menace to the people of the bordering villages. this species destroy the crops of the home gardens. this is a great economic loss but still a solution has not been provided by the government. 4. conclusions home gardens in dumbara conservation area comprises with high number of endemic species, timber species, and naturalized exotics with cultivated crops. people in these peripheral villages have no proper idea as how to attain plant conservation through the home gardens. awareness programs can direct villagers to obtain the maximum benefit of the home garden rather than going into the forest for extractable products. traditional knowledge of the fringe villagers should also be conserved. references acar, c., acar, h. and eroglu, e. (2007). evaluation of ornamental plant resources to urban biodiversity and cultural changing: a case study of residential landscapes in trabzon city (turkey). building and environment, 42(1): 218-229. albuquerque, u.p, andrade, l.h.c. and caballero, j. (2005). structure and floristic of home gardens in northeastern brazil. journal of arid environments, 62(3): 491-506. blanckaert, i., swennen, r., paredes-flores, m., rosas-lópez, r. and lira, r. (2004). floristic composition, plant uses and management practices in home gardens of san rafael coxcatlan, puebla, mexico. journal of arid environments, 57: 39–62. hochegger, k. (1998). farming like the forest: traditional home garden systems in sri lanka. margraf, weikersheim, germany: 203 pp. kehlenbeck, k, maass, b.l. (2004). crop diversity and classification of home gardens in central sulawesi, indonesia. agroforestry systems, 63: 53-62. mcconnell, d.j. (2003). the forest farms of kandy and other gardens of complete design. ashgate publishing, ltd.: 535 pp. dissanayake & hettiarachchi /journal of tropical forestry and environment vol. 3, no. 01 (2013) 24-36 36 pandey, c.b., lata, k., venkatesh, a. and medhi, r.p. (2006). diversity and species structure of home gardens in south andaman. tropical ecology, 47(2): 251-258. pandey, c.b., rai, r.b., singh, l. and singh, a.k. (2007). home gardens of andaman and nicobar, india. agricultural systems, 92(1-3): 1-22. tynsong, h. and tiwari, b.k. (2010). plant diversity in the home gardens and their significance in the livelihoods of war khasi community of meghalaya, north-east india. journal of biodiversity, 1(1): 1-11. richards, p.w., (1952). the tropical rain forest. cambridge university press, cambridge. appendix i: total number of trees/ shrubs belonging to different families in each village plant family pitawala polommana atanwala ratninda mahala kotuwa illukkumbura acanthaceae 8 0 0 0 0 4 aloaceae 46 5 5 6 17 0 amaranthaceae 136 42 8 0 21 24 anacardiaceae 0 3 0 0 0 0 apiaceae 270 46 52 62 27 31 araceae 0 0 0 5 0 0 asparagaceae 83 8 0 24 0 23 asteraceae 174 23 9 8 31 18 bromeliaceae 3 0 0 0 0 0 cannaceae 15 0 0 5 2 4 commelinaceae 3 0 0 0 3 0 convolvulaceae 33 2 0 31 0 0 crassulaceae 3 0 0 0 0 3 cucurbitaceae 73 12 7 13 5 12 euphorbiaceae 14 0 0 0 1 13 fabaceae 198 20 19 22 59 37 lamiaceae 431 47 122 98 37 62 malvaceae 142 7 17 35 23 24 melastomataceae 3 3 00 0 0 0 meliaceae 23 0 4 7 5 0 menispermaceae 0 0 3 2 0 0 pandanaceae 71 4 19 8 11 13 phtosporacea e 23 0 0 13 10 0 plumbaginaceae 12 0 0 9 3 0 poaceae 169 26 25 32 46 14 rubiaceae 79 0 0 55 2 12 rutaceae 134 26 21 17 21 13 sapindaceae 162 20 7 42 29 31 smilacaceae 4 0 0 4 0 0 solanaceae 2 0 0 0 0 0 tilliaceae 2 0 0 0 2 0 trapaceae 47 6 6 14 3 3 zingiberaceae 225 18 57 48 42 15 dangalle c.d. /journal of tropical forestry and environment vol. 3, no. 02 (2013) 39-52 39 the current status of the tiger beetle species of the coastal habitats of sri lanka c. d. dangalle 1 1 department of zoology, university of colombo, colombo 03 date received: 19-04-2013 date accepted: 12-09-2013 abstract the species of tiger beetles inhabiting coastal habitats of sri lanka have not been studied for nearly three decades. we report the tiger beetle species currently occupying the coastal habitats of the island, their distribution, microhabitats and habitat preferences. species and distributions reported nearly three decades from similar previous studies are also recorded. southern, north-western and western coastal belts (n=22) of sri lanka were investigated for the presence of tiger beetles. three species, hypaetha biramosa, lophyra (lophyra) catena, myriochila (monelica) fastidiosa, were recorded from eleven locations. m. (monelica) fastidiosa was reported for the first time, in a single location of the southern coastal belt. habitat parameters of the locations and the length of the body and mandible between h. biramosa and l. (lophyra) catena, were statistically compared to determine specific habitat preferences of the two species. analysis of variance using minitab 16.0 revealed that h. biramosa occupy habitats with high solar radiation (438-1023 w/m 2 ) and soil salinity (0.0-0.1ppt) while l. (lophyra) catena occupy habitats with low solar radiation (132-402) and non-saline soils (0.0 ppt). similar length of mandibles of these two species indicated that habitat selection of the species was not based on prey utilization, but may depend on the intensity of solar radiation and the level of soil salinity of the locations. keywords: tiger beetles, coastal habitats, distribution, habitat preferences, sri lanka 1. introduction tiger beetles (coleoptera, cicindelidae) are a group of predatory insects that are distributed throughout the world (pearson, 1988). about twenty-seven hundred (2,700) species have been described so far in almost every part of the terrestrial world except antarctica, tasmania and smaller oceanic islands and atolls (pearson, 2011). they occur in a wide variety of habitats which differ greatly in physical structure, soil characteristics and plant composition, but share the presence of bare patches of open ground (knisley, 2011). each species rarely occurs in more than one or a very few habitat types and habitat associations tend to be highly specific (morgan et al., 2000; rafi et al., 2010). one of the most common habitat types of tiger beetles are coastal areas with ocean beaches, sand dunes, sand bars, salt flats, estuaries, rocky shores, tidal flats with reeds and lagoons (wiesner, 1975; satoh et al., 2003; knisley and fenster, 2005; knisley, 2011). many species inhabit these environments and larvae and adults of tiger beetles typically occur in the same microhabitat (knisley, 2011). however, in recent years population declines have been noted in many species due to the spatial and temporal changes in coastal areas caused by flooding, erosion of the coast, deposition of sediments by water and wind, and anthropogenic activities (mawdsley, 2009; mouna et al., 2011). populations of north american tiger beetle species, cicindela dorsalis dorsalis and cicindela puritana have declined due to trampling of larval burrows by foot and vehicles (mawdsley, 2009). ohlone tiger beetle (cicindela ohlone) that occurs in coastal terrace grassland has experienced loss of several populations due to * correspondence: cddangalle@gmail.com tel: +94 77 34 55 63 issn 2235-9370 print / issn 2235-9362 online ©2013 university of sri jayewardenepura dangalle c.d. /journal of tropical forestry and environment vol. 3, no. 02 (2013) 39-52 40 encroachment of invasive grasses and herbaceous vegetation (knisley, 2011). cicindela hirticollis of north america has declined because of human construction and habitat alteration of the shoreline and increased beach usage and other human disturbances along the coast (knisley and fenster, 2005). however, while much is known about the coastal habitats, habitat threats and ecology of north american and european tiger beetles, very little has been published on species of other countries. information about the locations, habitats and habitat preferences play an important role in the development of conservation strategies for these insects. seven species of tiger beetles have been recorded from the coastal areas of sri lanka (weisner, 1975; naviaux, 1984; acciavatti and pearson, 1989) (table 1 and figure 1). hypaetha biramosa is confined to the sandy ocean beaches and calm bays of the island while the other species can be found in coastal habitats and other inland localities away from the coast. callytron limosa, hypaetha quadrilineata, myriochila (monelica) distinguenda, cylindera (eugrapha) singalensis, lophyra (lophyra) cancellata have been recorded along major rivers, brackish mud puddles and inland lakes, whereas lophyra (lophyra) catena occupies upland areas of open grassland, old fields, dirt roads and margins of rivers (acciavatti and pearson, 1989). none of these species are endemic. they occur in countries of the indian subcontinent in india, pakistan, burma, bangladesh, nepal and in south-east asia, thailand, china and malaysia (acciavatti and pearson, 1989). as indicated in table 1 these species have not been reported since 1984. therefore, current distributions, habitat and their characteristics remain uncertain. table 1: tiger beetle species recorded from coastal locations of sri lanka species microhabitat location (recorded year and reference given within brackets) callytron limosa along the coast. chilaw (1979) {acciavatti and pearson, 1989} hypaetha biramosa intertidal zone and undisturbed outer sandy ocean beaches. on the sea shore not more than 200 yards from the edge of the sea. sea border on clean, level sandy banks. prefers calm bays. mannar (1981), pesalai (1981), trincomalee (1972) {acciavatti and pearson, 1989} galle (1970), hikkaduwa (1970), hendala (1979), kalutara (1979), nilaveli (1981), kalkudah (1981), pottuvil (1983) {naviaux, 1984} hypaetha quadrilineata sandy areas along coastal beaches. colombo {horn, 1904} myriochila (monelica) distinguenda brackish mud puddles near the ocean. puttalam (1981), padaviya (1970), kilinochchi (1970), mannar (1976) {acciavatti and pearson, 1989} cylindera (eugrapha) singalensis flat, muddy open places near the sea. hambantota (1921) {acciavatti and pearson, 1989} lophyra (lophyra) cancellata dry, warm ground close to the sea. colombo (1970), galle (1970), hikkaduwa (1970) {weisner, 1975} lophyra (lophyra) catena lagoons by the ocean. hendala (1979), bentota (1979), puttalam (1981) {naviaux, 1984} aluthgama (1984) {acciavatti and pearson, 1989} dangalle c.d. /journal of tropical forestry and environment vol. 3, no. 02 (2013) 39-52 41 figure 1: distribution of tiger beetle species in coastal locations of sri lanka the coastal ecosystems of sri lanka provide the basis for the marine fisheries industry and coastal tourism, while serve as a host of other economic and social benefits (iucn 2002). these activities, most notably ill-designed coastal structures, construction of hotels and other buildings too near the shoreline, sand and coral mining, removal of coastal vegetation and reef breaking have contributed to coastal erosion and have resulted in the degradation and loss of coastal land (lowry and wickremeratne, 1988). further, in december 2004, the sri lankan coastline was devastated by the indian ocean tsunami and the entire coastline with the exception of parts of the north-western coastline was severely affected. coastal tiger beetles are known to be very sensitive to disturbances on the coastline and they are known to experience population bottlenecks caused by natural disasters such as storms or tsunami (satoh et al., 2004; mawdsley, dangalle c.d. /journal of tropical forestry and environment vol. 3, no. 02 (2013) 39-52 42 2009). therefore, it is imperative that the species inhabiting the coastal areas of sri lanka be recorded and investigated. the present study intends to record the tiger beetle species of coastal habitats of sri lanka, investigate the current locations and distribution of tiger beetle species of sri lanka, study the microhabitats and habitat segregation of species and record habitat preferences of each species. the study will provide information for assessing the conservation status of coastal tiger beetles of sri lanka and for providing habitat management strategies for the group. 2. methodology 2.1 study area twenty-two (22) coastal locations of sri lanka were surveyed for the occurrence of tiger beetles from may 2003 to march 2008. the locations were situated in the north-western, western and southern provinces of sri lanka in the districts of puttalam, gampaha, colombo, kalutara, galle, matara and hambantota (table 2 and figure 2). sandy beaches, areas with vegetation, paths and trails, rocks, salt flats, sand bars and sand dunes were searched for tiger beetles between 09.00-17.00 h. 2.2 collection and identification of tiger beetle species tiger beetles were collected using a standard insect net and preserved in 70% alcohol. permission to make collections of tiger beetles was obtained through a permit issued by the department of wildlife conservation, ministry of environment and natural resources of sri lanka. taxonomic keys of the cicindela of the indian subcontinent by acciavatti and pearson (1989), descriptions of horn (1904) and fowler (1912) were used to identify the species and confirmation of identification was done through comparisons with type specimens available at the national museum of colombo and natural history museum, london. taxonomic names of species with the present nomenclatural changes are based on weisner, 1992. 2.3 measurement of body length and mandible length body length and mandible length were estimated for thirty-three tiger beetles. the thirty-three specimens consisted of fifteen specimens of hypaetha biramosa, fifteen specimens of lophyra (lophyra) catena and three specimens of myriochila (monelica) fastidiosa (table 3). body length was estimated by measuring the distance from the frons of the head to the elytral apex when the head was in the normal feeding position. caudal spines on the elytral apex were disregarded. based on the references of acciavatti and pearson (1989), mccairns et al. (1997) and zerm and adis (2001), body length of beetles was categorized as follows. less than 8 mm – very small 8 to 10 mm – small 10 to 15 mm – medium 15 to 20 mm – large more than 20 mm – very large mandible length was estimated by measuring the distance from the articulation point to the tip of the left mandible. based on pearson and juliano (1993) and satoh and hori (2004) mandibles of beetles were categorized according to the following size groups. < 2 mm – small 2 to 3 mm – medium > 3 mm – large dangalle c.d. /journal of tropical forestry and environment vol. 3, no. 02 (2013) 39-52 43 measurements of both body length and mandible length were taken using a dissecting microscope (nikon corporation se, japan) with an eyepiece graticule (nikon, tokyo, japan) that was calibrated by an objective micrometer (olympus, japan). body length and mandible length of h. biramosa and l. (lophyra) catena were compared using oneway analysis of variance (minitab 16.0) and the p statistic at 95% significance was calculated. morphological parameters of m. (monelica) fastidiosa were not subjected to statistical analysis as only three specimens were found from a single location, a number too low for statistical comparison. boxplots were created for the morphological measurements that were significant between h. biramosa and l. (lophyra) catena using boxplot option in graphs (minitab 16.0). table 2: coastal locations of sri lanka investigated for tiger beetles location date of investigation puttalam lagoon, puttalam district, north-western province june 2004 mundel lake, puttalam district, north-western province june 2004 chilaw coast, puttalam district, north-western province june 2004 marawila coast, puttalam district, north-western province june 2004 poruthota coast, gampaha district, western province june 2004 mount lavinia beach, colombo district, western province october 2004, march 2008 thalpitiya coast, kalutara district, western province june 2004 katukurunda coast, kalutara district, western province june 2004, july 2006 maggona coast, kalutara district, western province june 2005 aluthgama coast, kalutara district, western province june 2004, july 2006 bentota beach, galle district, southern province march 2008 induruwa coast, galle district, southern province june 2005 kosgoda beach, galle district, southern province may 2003, november 2005 galle harbor, galle district, southern province march 2005 kathaluwa coast, galle district, southern province march 2005 morampitigoda coast, galle district, southern province march 2005 habaraduwa beach, galle district, southern province may 2003, august 2007 matara beach, matara district, southern province may 2003, august 2007 hambantota salt flats, hambantota district, southern province november 2004 hambantota beach, hambantota district, southern province november 2004 kirinda, hambantota district, southern province november 2005 yala salterns, hambantota district, southern province november 2005 dangalle c.d. /journal of tropical forestry and environment vol. 3, no. 02 (2013) 39-52 44 figure 2: the coastal locations of sri lanka investigated for the presence of tiger beetles 2.4 measurement of habitat parameters spatial coordinates and elevation was recorded using a marine/outdoor geographical positioning system device (gps 315, magellan systems corp., taiwan). air temperature, solar radiation, relative dangalle c.d. /journal of tropical forestry and environment vol. 3, no. 02 (2013) 39-52 45 humidity and wind speed was measured using a portable integrated weather station (health enviromonitor, davis instrument corp., usa). a soil sample of the habitat was used to determine the soil temperature (using insert soil thermometer sg 680-10), soil moisture (determined by selecting five random spots of a locality and collecting samples to a depth of 10 cm and estimating the difference in weight before and after oven drying to 107-120°c in the laboratory), soil ph (using portable soil ph meter westminister no.259) and soil salinity (using a ysi model 30 hand-held salinity meter). vegetation type and distribution was also noted. habitat parameters of the locations of h. biramosa and l. (lophyra) catena were compared using one-way analysis of variance (minitab 16.0) and tukey’s multiple comparison method. habitat parameters of m. (monelica) fastidiosa were not subjected to statistical analysis as the species was found only in one location. boxplots were created for the habitat parameters that were significant between h. biramosa and l. (lophyra) catena using boxplot option in graphs (minitab 16.0). further, habitat parameters of the locations of tiger beetles were compared with the locations in which tiger beetles were not recorded using the same statistical procedure. 3. results 3.1 locations of tiger beetle species tiger beetles were encountered in eleven (11) coastal locations of sri lanka in the districts of puttalam, kalutara, galle, matara and hambantota (table 4). species recorded before the 2004 tsunami were encountered in the same locations after the tsunami (table 2). three tiger beetle species, hypaetha biramosa fabricius 1781, lophyra (lophyra) catena fabricius 1775, myriochila (monelica) fastidiosa dejean 1825, were found in these locations between 09.30-16.30 h (table 4 and figure 3). h. biramosa was found on the sandy beach near the swash where there was no vegetation, while l. (lophyra) catena occupied areas with vegetation about 25 m inland from the beach. both species were found together at bentota beach in which h. biramosa occupied the shore near the water edge, while l. (lophyra) catena occupied the more inland area away from the shore. m. (monelica) fastidiosa occurred in only one location, near the water edge of a salt flat (table 4). table 4: coastal locations of tiger beetle species recorded in the study location coordinates and elevation species microhabitat chilaw coast, puttalam district, north-western province 7°34`79n 79°47`27e 0.00 m lophyra (lophyra) catena sand dunes katukurunda coast, kalutara district, western province 6°33`28n 79°57`92e 9.75 m lophyra (lophyra) catena amongst vegetation away from the beach bentota beach, galle district, southern province 6°23`99n 80°00`26e 0.00 9.50 m hypaetha biramosa lophyra (lophyra) catena sandy beach amongst vegetation away from the beach induruwa coast, galle district, southern province 6°22`05n 80°00`68e 8.00 m hypaetha biramosa wet sandy beach kosgoda beach, galle district, southern province 6°21`24n 80°00`59e 1.40 m hypaetha biramosa wet sandy beach dangalle c.d. /journal of tropical forestry and environment vol. 3, no. 02 (2013) 39-52 46 location coordinates and elevation species microhabitat aluthgama coast, kalutara district, western province 6°23`58n 80°00`33e 9.14 m lophyra (lophyra) catena footpath amongst vegetation away from the beach morampitigoda coast, galle district, southern province 6°02`33n 80°01`41e 0.00 m hypaetha biramosa wet sandy beach habaraduwa beach, galle district, southern province 6°02`11n 80°11`45e 0.00 m hypaetha biramosa sandy beach matara beach, matara district, southern province 6°03`11n 80°12`26e 0.09 m hypaetha biramosa sandy beach hambantota salt flats, hambantota district, southern province 6°07`00n 81°03`00e 1.00 m myriochila (monelica) fastidiosa near water edge kirinda, hambantota district, southern province 6°13`78n 81°19`11e 3.02 m lophyra (lophyra) catena foot path amongst vegetation 3.3 body length and mandible length all three species of coastal tiger beetles were medium sized with body lengths ranging from 10.38–13.63 mm and mandible lengths ranging from 1.50–2.58 mm (table 3). the body lengths of h.biramosa and l.(lophyra) catena were significantly different (f = 8.4, p = 0.007), l. (lophyra) catena being slightly smaller than h. biramosa (table 3 and figure 4). the mandible lengths of the two species did not differ significantly. figure 3: the coastal tiger beetle species of sri lanka hypaetha biramosa lophyra (lophyra) catena myriochila (monelica) fastidiosa dangalle c.d. /journal of tropical forestry and environment vol. 3, no. 02 (2013) 39-52 47 table 3: mean body length and mandible length of coastal tiger beetle species ± standard error and range in parentheses species number of specimens average body length (mm) average mandible length (mm) hypaetha biramosa 15 12.10 ± 0.24 (10.50 – 13.63) 1.69 ± 0.19 (1.50 – 2.08) lophyra (lophyra) catena 15 11.27 ± 0.16 (10.48 – 12.30) 2.42 ± 0.05 (2.23 – 2.58) myriochila (monelica) fastidiosa 03 11.21 ± 0.65 (10.38 – 12.50) 2.24 ± 0.13 (2.10 – 2.50) lophyrahypaetha 14.0 13.5 13.0 12.5 12.0 11.5 11.0 10.5 species b o d y l e n g t h ( m m ) body length of coastal tiger beetle species figure 4: body length variation of hypaetha biramosa and lophyra (lophyra) catenaof coastal habitats 3.4 habitat parameters the elevation, climatic and soil parameters of the coastal locations of tiger beetles are given in table 5. locations of h. biramosa and l.(lophyra) catena are significantly different in solar radiation and soil salinity (table 5). the solar radiation of the locations of h. biramosa was significantly higher than that of l. (lophyra) catena (f = 10.19, p < 0.05) (table 5, figure a). soil salinity of h. biramosa locations ranged from 0 – 0.1 ppt, while l. (lophyra) catena was found on non-saline soils (f = 9.00, p < 0.05) (table 5, figure b). statistical differences were not found between the habitat parameters of the locations of tiger beetles and locations in which tiger beetles were not recorded (table 6). dangalle c.d. /journal of tropical forestry and environment vol. 3, no. 02 (2013) 39-52 48 table 5: habitat characteristics of the coastal locations of tiger beetle species parameter all locations (n=11) locations of hypaetha biramosa (n=6) locations of lophyra (lophyra) catena (n=5) locations of myriochila (monelica) fastidiosa (n=1) elevation (m) 3.97 ± 1.41 (0.00 – 9.75) 2.06 ± 1.51 (0.00 – 8.00) 7.10 ± 2.37 (0.00 – 9.75) 1.00 air temperature (°c) 35.50 ± 1.13 (31.00 – 41.00) 34.20 ± 1.77 (31.00 – 41.00) 37.75 ± 1.18 (36.00 – 41.00) 33.00 solar radiation (w/m 2 ) 490.80 ± 103.31 (132.00 – 1023.00) 734.20 ± 127.61 (438.00 – 1023.00) 244.25 ± 57.46 (132.00 – 402.00) 260.00 relative humidity (%) 61.00 ± 3.23 (45.00 – 77.00) 62.20 ± 5.34 (45.00 – 77.00) 58.75 ± 5.22 (45.00 – 70.00) 64.00 wind speed (mph) 6.70 ± 2.52 (0.00 – 22.00) 4.00 ± 1.92 (0.00 – 9.00) 7.00 ± 5.07 (0.00 – 22.00) 19.00 soil temperature (°c) 34.71 ± 0.95 (30.50 – 39.00) 34.00 ± 0.00 36.13 ± 0.97 (35.00 – 39.00) 30.50 soil moisture (%) 4.60 ± 1.41 (0.18 – 10.71) 5.97 ± 2.04 (0.68 – 10.23) 1.36 ± 0.78 (0.18 – 3.50) 10.71 soil ph 7.62 ± 0.15 (7.00 – 8.20) 7.82 ± 0.16 (7.40 – 8.20) 7.50 ± 0.29 (7.00 – 8.00) 7.00 soil salinity (ppt) 0.06 ± 0.02 (0.00 – 0.20) 0.08 ± 0.03 (0.00 – 0.10) 0.00 ± 0.00 0.20 lophyrahypaetha 1000 800 600 400 200 0 species s o la r r a d ia t io n ( w / m 2 ) solar radiation preference of tiger beetle species lophyrahypaetha 0.10 0.08 0.06 0.04 0.02 0.00 species s a li n it y ( p p t ) soil salinity preference of tiger beetle species (a) (b) figure 5: variation of significant habitat parameters (a) solar radiation (b) soil salinity in coastal locations of hypaetha biramosa and lophyra (lophyra) catena dangalle c.d. /journal of tropical forestry and environment vol. 3, no. 02 (2013) 39-52 49 table 6: comparison of habitat characteristics of locations in which tiger beetles were recorded and not recorded parameter ocurrence of tiger beetles present (n=11) absent (n=11) elevation (m) 3.97 ± 1.41 4.85 ± 2.10 air temperature (°c) 35.50 ± 1.13 31.20 ± 2.55 solar radiation (w/m 2 ) 490.80 ± 103.31 401.74 ± 119.33 relative humidity (%) 61.00 ± 3.23 66.82 ± 2.38 wind speed (mph) 6.70 ± 2.52 3.49 ± 0.44 soil temperature (°c) 34.71 ± 0.95 32.89 ± 0.24 soil moistuure (%) 4.60 ± 1.41 3.98 ± 0.95 soil ph 7.62 ± 0.15 7.78 ± 0.65 soil salinity (ppt) 0.06 ± 0.02 0.05 ± 0.01 4. discussion and conclusions the present study revealed three species of tiger beetles, hypaetha biramosa, lophyra (lophyra) catena, myriochila (monelica) fastidiosa, from coastal habitats of sri lanka. however, seven species have been reported from previous studies and collections that include h. biramosa and l. (lophyra) catena whereas m. (monelica) fastidiosa was recorded for the first time in the present study. according to previous literature, h. biramosa is the only tiger beetle species confined to the coastal habitats of the island. the other six species have been recorded on edges of rivers, lakes, grasslands, old fields and sunny forest clearings in addition to coastal habitats (acciavatti and pearson, 1989). l. (lophyra) catena was encountered on banks of reservoirs and landscaped gardens by the first author during 2003 – 2004 (dangalle et al., 2012a; dangalle et al., 2012b). therefore, the current absence of certain tiger beetle species from the coastal locations that they previously occupied maybe due to the extirpation of species from coastal habitats to other habitat types that they prefer. cicindela hirticollis of north america which was abundant on wet beach sand, sandbars or moist pans within dune fields disappeared from many sites in the past 30-40 years because of increased beach usage and other human disturbance along the coast, and has been recovered from a few sites along rivers (knisley and fenster, 2005). cicindela ohlone which occurred in coastal terrace grasslands of california, currently occupies densely vegetated grasslands with dirt trails and trails used by mountain bikers and walkers (knisley, 2011). hypaetha quadrilineata showed a rapid dispersal to inland habitats when local conditions became unfavourable along the coastal beaches of iran (acciavatti and pearson, 1989). further, the endemic tiger beetle species, cicindela (ifasina) willeyi of sri lanka is known to have extirpated from it’s historical locations to new locations due to the unsuitability and loss of its former habitats (dangalle et al., 2011a). the endemic species, cicindela (ifasina) waterhousei has also become locally displaced from its previous locations to a single riverine location of the island (dangalle et al., 2011b). therefore, the tiger beetle species that once occupied the coastal locations of sri lanka may currently exist in other locations with suitable habitat conditions which they prefer. however, investigations in some previous coastal locations of tiger beetles from which species are not currently recorded revealed similar habitat conditions to that of the locations in which tiger beetles were recorded (table 6). therefore, further investigations focusing on prey availability and abundance, and predators of tiger beetles are required to explain the non-availability of dangalle c.d. /journal of tropical forestry and environment vol. 3, no. 02 (2013) 39-52 50 certain tiger beetle species along the coastal belt. investigations of the historical locations of tiger beetles including locations of the northern province (kilinochchi, pesalai, mannar) and eastern province (nilaveli, trincomalee, kalkudah, pottuvil) which could not be investigated due to security conditions that prevailed in the country at that time are also required. our results revealed the presence of tiger beetles in the same locations even after the tsunami of 2004. however, the immediate impacts of the tsunami were not assessed in the present study and the coastal habitats can be expected to have recovered over several months providing bare ground for tiger beetles to encounter mates, oviposit and find prey. m. (monelica) fastidiosa has been reported from old fields, grasslands and forest paths (acciavatti and pearson, 1989). further, the species was encountered by the first author from four reservoir ecosystems of the island during 2004 – 2005 (dangalle et al., 2012a). currently, the reservoir ecosystems of sri lanka are dominated by the tiger beetle calomera angulata which occurs as large single species populations or cooccurs with other tiger beetle species (dangalle et al., 2012a). m. (monelica) fastidiosa co-occurred with calomera angulata in three of the reservoir ecosystems that it occupied and was only found as a single species population in the nuwarawewa reservoir (dangalle et al., 2012a). co-occurring tiger beetle species are known to compete for food resources, ovipositional sites and mating (tigreros and kattan, 2008; brosius, 2010). cicindela nevadica lincolniana of the saline habitats of nebraska that co-occurs with three other species of tiger beetles has suffered a drastic decline in population due to competition for food resources and oviposition sites (brosius, 2010). further, cicindela hirticollis abrupta of sacramento valley, california has disappeared from most of it’s historic range while another tiger beetle cicindela oregona was found at these sites (knisley and fenster, 2005). c. (ifasina) waterhousei of sri lanka is also known to have become locally displaced from its previous locations due to competition for food, thermal resources, oviposition sites and larval resources by other tiger beetle species (dangalle et al., 2011b). therefore, the incidence of m. (monelica) fastidiosa in a coastal habitat maybe an indication of the species exploiting a new habitat due to competition exerted by co-occurring tiger beetle species. when considering the coastal habitats of species, h. biramosa was found on sandy beaches near the swash while l. (lophyra) catena occurred in habitats away from the beach amongst coastal vegetation. these two microhabitats were similar in most of the climatic and soil characteristics but differed significantly in solar radiation and soil salinity. microhabitat characteristics are important in tiger beetle oviposition site choice and females have been shown to choose sites based on shade, soil type, salinity, moisture and vegetation cover (cornelisse et al., 2013). certain species prefer hot, dry conditions and find suitable moist soils for oviposition and larval development. for example cicindela limbata albissima which has evolved as a sand dune specialist tolerates hot, dry, sunny conditions whereas generalist species are less tolerant of these conditions (romey and knisley, 2002). likewise, h. biramosa which has been confined to the coastal habitats of the island since historical times may have evolved to tolerate high solar radiation conditions in contrast to the more generalist species l. (lophyra) catena. oviposition site selection of tiger beetles is also based on soil salinity and certain species prefer saline soils while others prefer non-saline soils. salinity of soils have a negative impact on vegetation and produces dry sunny habitats lacking shade (brosius, 2010). according to dangalle et al. (2012b) soil salinity is an important factor determining habitat specificity of h. biramosa of sri lanka. h. biramosa and l. (lophyra) catena are medium-sized beetles with similar color pattern. l. (lophyra) catena is slightly smaller than h. biramosa and this difference tends to be significant (p < 0.05). however, the two species have similar mandible lengths that indicate preference for prey of similar size. therefore, it is highly possible that habitat segregation of h. biramosa and l. (lophyra) catena is not influenced by the size of prey in microhabitats. the present study strongly indicates that physiological preferences that are conservative and characteristic for the two species determine their utilization of different microhabitats. dangalle c.d. /journal of tropical forestry and environment vol. 3, no. 02 (2013) 39-52 51 acknowledgements: we wish to thank the national science foundation of sri lanka (research grant no. rg/2003/zoo/01) for funding the present study. we are also greatly indebted to the department of zoology, university of colombo; the natural history museum of london, united kingdom and the department of wildlife conservation of sri lanka. we are grateful to prof. nimal dangalle and ms. dinesha senarathna, department of geography, university of kelaniya, sri lanka for their assistance in the preparation of maps and locational lists. references acciavatti, r.e., pearson d.l., 1989. the tiger beetle genus cicindela (coleoptera, insecta) from the indian subcontinent. annals of carnegie museum. 58(4), 77-355. brosius, t.r., 2010. niche specialization and conservation biology of cicindela nevadica lincolniana. dissertations and student research in entomology, university of nebraska, lincoln, pp. 130. cornelisse, t.m., vasey, m.c., holl, k.d., letourneau, d.k., 2013. artificial bare patches increase habitat for the endangered ohlone tiger beetle (cicindela ohlone). journal of insect conservation. 17(1), 17-22. dangalle, c., pallewatta, n., vogler, a., 2011a. the current occurrence, habitat and historical change in the distributional range of an endemic tiger beetle species cicindela (ifasina) willeyi horn (coleoptera: cicindelidae) of sri lanka. journal of threatened taxa. 3(2), 1493-1505. dangalle, c., pallewatta, n., vogler, a.,2011b. the occurrence of the endemic tiger beetle cicindela (ifasina) waterhouseiin bopath ella, ratnapura, sri lanka. journal of the national science foundation of sri lanka. 39(2), 163-168. dangalle, c., pallewatta, n., vogler, a., 2012a. tiger beetles (coleoptera: cicindelidae) of ancient reservoir ecosystems of sri lanka. journal of threatened taxa. 4(4), 2490-2498. dangalle,c.d., pallewatta, n., vogler, a.p. 2012b. habitat specificity of tiger beetle species (coleoptera, cicindelidae) of sri lanka. cicindela.44(1), 1-32. fowler, w.w.,1912. fauna of british india including ceylon and burma {coleoptera general introduction and cicindelidae and paussidae}, today and tomorrow’s printers and publishers, new delhi. horn, w., 1904. the cicindelidae of ceylon. spolia zeylanica. 2(5), 30-45. iucn, 2002. regional technical assistance for coastal and marine resource management and poverty reduction in south asia (adb reta 5974) – situation analysis report: sri lanka component. knisley, c.b., fenster, m.s., 2005. apparent extinction of the tiger beetle, cicindela hirticollis abrupt (coleoptera: carabidae: cicindelinae). the coleopterists bulletin. 59(4), 451-458. knisley, c.b., 2011. anthropogenic disturbances and rare tiger beetle habitats: benefits, risks, and implications for conservation. terrestrial arthropod reviews. 4, 41-61. lowry, k., wickremeratne, h.j.m., 1988. coastal area management in sri lanka. coastal management. 263-293. mawdsley, j.r., 2009. taxonomy, ecology, and phylogeny of species of lophyra motschulsky 1859, subgenus eriolophyra rivalier 1948 (coleoptera cicindelidae). tropical zoology. 22, 57-70. mccairns, r.f., freitag, r., rose, h.a., mcdonald, f.j.d.,1997. taxonomic revision of the australian cicindelidae (coleoptera), excluding species of cicindela. invertebrate taxonomy.11, 599-687. morgan, m.m., knisley, c.b., vogler, a.p., 2000. new taxonomic status of the endangered tiger beetle cicindela limbata albissima (coleoptera: cicindelidae): evidence from mtdna. annals of the entomological society of america. 93(5), 1108-1115. naviaux, r.,1984.coleoptera, cicindelidae. les cicindelés de sri lanka. revue scientifique du bourbonnais. 57-80. dangalle c.d. /journal of tropical forestry and environment vol. 3, no. 02 (2013) 39-52 52 pearson, d.l., juliano, s.a.,1993. evidence for the influence of historical processes in co-occurrence and diversity of tiger beetle species, in: ricklefs, r.e., schulter, d. (eds.),species diversity in ecological communities. chicago university press, chicago, pp. 194-202. pearson, d.l., 1988. biology of tiger beetles. annual review of entomology. 33, 123-147. pearson, d.l., 2011. six-legged tigers. spring. 19-23. rafi, m.a., jurgen, w., matin, m.a., zia, a., sultan, a., naz, f., 2010. faunistics of tiger beetles (coleoptera: cicindelidae) from pakistan. journal of insect science. 10, 1-23. romey, w.l., knisley, c.b., 2002. microhabitat segregation of two utah sand dune tiger beetles (coleoptera: cicindelidae). the southwestern naturalist. 47(2), 169-174. satoh, a., hori, m., 2004.interpopulation differences in the mandible size of the coastal tiger beetle lophyridia angulata associated with different sympatric species. entomological science. 7, 211-217. satoh, a., ueda, t., enokido, y., hori, m., 2003. patterns of species assemblages and geographical distributions associated with mandible size differences in coastal tiger beetles in japan. population ecology. 45, 67-74. tigreros, n., kattan, g.h., 2008. mating behavior in two sympatric species of andean tiger beetles (cicindelidae). boletin del museo de entomologia de la universidad del valle. 9(1), 2228. wiesner, j., 1975. notes on cicindelidae of india and sri lanka. cicindela. 7(4), 61-70. wiesner, j.,1992. checklist of the tiger beetles of the world (coleoptera: cicindelidae),verlag erna bauer, keltern, germany. zerm,m., adis, j.,2001. spatio-temporal distribution of larval and adult tiger beetles (coleoptera: cicindelidae) from open habitats in central amazonian floodplains (brazil). studies on neotropical fauna and environment.36(3), 185-198. ruwanpathirana/journal of tropical forestry and environment vol. 4, no 01 (2014) 1-13 1 feature article development of a timber property classification based on the end-use with reference to twenty sri lankan timber species n.d. ruwanpathirana state timber corporation, sri lanka abstract an investigation was carried out on selected 20 timber species of sri lanka to study different wood properties, i.e., wood density, modulus of rapture, modulus of elasticity, compression parallel to grain, shrinkage/movement, workability (sawing, nailing, sanding and finishing), treatability of preservative, timber durability, timber texture by vessel diameter and some gross properties, timber colour and present timber uses. based on the results, an attempt was made to classify the studied timber species into property levels. the final objective of this study was to develop relationships between the end-uses of timber and their property requirements and levels with reference to 20 sri lankan timber species. timber selection for the use in sri lanka is species-oriented and sometimes it is based on the traditional use. based on wood properties of 20 sri lankan timber species selected, an attempt was made to recognise the most important wood properties and their levels to develop a four end-use property classification. in general, the proposed end-use property classification in this study could be differentiated as (i.) for building construction, (ii.) for furniture and joinery (iii.) for light construction, and (iv.) for miscellaneous uses. among the selected timber species, dipterocarpus zeylanicus is eminently suitable for under-water work. eucalyptus microcorys is regarded as one of the best timbers for dancing floors. these specialty and causative factors of timber, however, must be explored and documented in order to prepare end-use property classification for miscellaneous use. 1. introduction sri lanka a small island of 6,561,000 ha, posses a significant biodiversity along with various tree species. total natural forest cover in sri lanka is 1,951,472 ha which consists 1,521,987 ha of closed canopy forests and 429,485 ha of open canopy forests. there are over 350 timber tree species present in these forests and other crown lands. present annual timber consumption in sri lanka is 1.6 million m 3 from which around 10% is supplied by imports. forest plantations and homegardens that have the potential of producing good quality timber, contribute about 10% and 40% of national timber requirements respectively. * correspondence: nimalruwan@gmail.com tel: +94 112885853 issn 2235-9370 print/issn 2235-9362 online © university of sri jayewardenepura ruwanpathirana/journal of tropical forestry and environment vol. 4, no 01 (2014) 1-13 2 wood properties vary with timber species and each and every property may bring a unique value and important feature to timber and its end-use. this variability of timber serves a variety of uses and if a particular timber is good for one purpose it may not be useful for another purpose. in general, selection of timber species for particular end-use depends on technical performance of timber such as durability, movement, strength, stiffness and toughness, permeability and ease of processing. lack of knowledge on mechanical properties of structural timber leads to structural application of unnecessarily high safety margins in timber design. as far as wood properties of sri lankan timber species are concerned, comprehensive studies were not conducted on physical properties, mechanical properties, anatomical properties, gross features, working properties, durability, timber seasoning and preservation. timber selection for the use is species oriented, sometimes on the basis of traditional use, however, more frequently on considerations of availability, cost, size and performance. therefore information is much useful for the selection of timber species for the end-use because an appropriate combination such technical information is often among the last to be considered at present. an end-use property classification can be defined in the first place for building construction, furniture and joinery, light construction work and miscellaneous uses, flooring and furniture. for instance, property requirements and preferable property level for property classification for major user groups can be judged based on experience of the factors which affecting performance, and guided by standards and specifications. this paper provides most of important wood properties with its property levels such as density, some mechanical properties, natural durability and treatability, dimensional movement and seasoning properties, working properties, gross features (colour and texture). hence using this information on property requirements for a product, it is possible to select the suitable timber species in which required technical information is available. the objectives of the present study were to determine wood properties of 20 selected sri lankan timber species (table 1), to classify the studied wood properties into property levels and to develop relationships between the end-uses of timber and their property requirement and levels with reference to twenty sri lankan timber species. table 1: list of commonly used timber species. no name scientific name family 1 acacia acacia malanoxylon fabaceae 2 ginisapu michelia champaca magnoliaceae 3 grandis eucalyptus grandis myrtaceae 4 havarinuga alstonia macrophylla apocynaceae 5 hora dipterocarpus zeylanicus dipterocarpaceae 6 ketakala bridelia retusa phyllanthaceae 7 khaya khaya senegalensis meliaceae 8 kohomba azadirachta indica meliaceae 9 kolon adina cordifolia rubiaceae 10 kos artocarpus heterophyllus moraceae 11 kumbuk terminalia arjuna combretaceae ruwanpathirana/journal of tropical forestry and environment vol. 4, no 01 (2014) 1-13 3 12 liyan homalium zeylanicum salicaceae 13 lunumidella melia dubia meliaceae 14 mahogany swietenia macrophylla fabaceae 15 mee madhuca longifolia sapotaceae 16 microcorys eucalyptus microcorys myrtaceae 17 para mara albizia saman fabaceae 18 rubber hevea brasiliensis euphorbiaceae 19 teak tectona grandis verbenaceae 20 toona toona ciliata fabaceae 2. materials and methods authentic timber samples of 20 sri lankan timber species were collected from the research division of state timber corporation (stc) along with fresh wood samples from the mature trees in the field. wood samples and disks were cut from each species at breast height of the tree. the collected specimens from the two sources mentioned above were compared anatomically with each other for the confirmation of species identity. a radial strip was cut from each disk for the investigation of anatomical characteristics. required number of timber samples with necessary dimensions were cut and removed for the measurement of specific gravity, mechanical properties, shrinkage and movement, durability testing at grave yard, boron preservation, working properties, wood texture and heartwood colour. 2.1 timber density a radial strip cut from each disk was used for the measurement of timber density. timber density was determined on the basis of oven-dry weight and green volume. timber density of 20 species studied were grouped into four categories as light wood (<= 500 kgm -3 at 12% moisture content), medium density wood (500-640 kgm -3 ), high density wood (640-840 kgm -3 ) and very high density wood (>840 kgm -3 ). 2.2 shrinkage and movement wood specimens (2×2 cm in cross section and 5 cm long) in green state were weighed up to the accuracy of 0.001 g and conditioned to achieve constant weights at about 10-12% moisture and then oven-dried at 103 0 c until a constant weight was obtained. lengths of the specimens along radial and tangential plane at green, air dry and oven dry conditions were measured and radial and tangential shrinkages were calculated. these samples, prior to use for oven dry measurement were subjected to determine the timber movement under atmospheric condition from relative humidity of 80% to relative humidity of 60%. shrinkage and movement properties levels were categorised into three groups as high (>12%), medium (7%-12%) and low (<7%). 2.3 mechanical properties static bending test of air-dried 2×2 cm (cross section) and 30 cm long specimen was carried out using a universal test machine. deflections and the corresponding loads were recorded and load deflection curves were prepared. modulus of rapture and modulus of elasticity were ruwanpathirana/journal of tropical forestry and environment vol. 4, no 01 (2014) 1-13 4 calculated. compression perpendicular to grain was also carried out by same machine using timber sample of 2×2 cm (cross section) and 6.2 cm long specimen. 2.4 wood durability. heartwood timber samples (5×5×60 cm) were buried in ground following the principle of grave yard experiment and deterioration of timber with time table were observed. timber durability was classified as non-durable (<5 years), moderately durable (5-10 years) and durable (>10 years). in addition, ground survey was conducted to collect information of timber durability. 2.5 timber treatability with boron preservation depth of penetration and retention of boron preservative were calculated after timber samples were immersed in the boron solution complying for standard procedure. boron retention levels were classified as easy (>10 kgm -3 ), medium (6-10 kgm -3 ) and difficult (<6 kgm -3 ). 2.6 wood colour wood samples containing both heartwood and sapwood were used to determine wood colour according to iawa (1989) category no. 197 to 202 by naked eye. heartwood colour was categorised mainly into four groups, namely, (i.) basically brown or shade of brown, (ii.) red or shade of red, (iii.) yellow or shade of yellow and (iv.) white to grey. visible differentiation of heartwood color from sapwood was also studied. 2.7 anatomical characteristics a radial strip taken from the pith to bark was used for the investigation of anatomical characteristics. these wood samples were boiled in water for about two hours to soften them. each wood sample was shaped and sized into wood block of 2×2×3 cm. transverse, radial and tangential sections at the range of 10-15 µm thickness were obtained by using a sledge microtome (model leica sm2000 r). the permanent slides of wood were prepared after dehydrated and stained in safranin. sections were mounted using canada balsam using standard procedure. microscopic observations of each slide were made for qualitative and quantitative analysis of parameters under the light microscope at 4×10 magnifications. measurements on wood anatomical features were taken after photomicrographs of each slide were made by olympus microscope and micromertics se premium 4 software available in the research division of stc. measurements of tangential vessel diameter were used to determine the wood texture. 2.8 wood texture mean vessel tangential diameter, ray width and ray height were measured in this study from which average tangential diameter of the vessel (µm) was used to determine wood texture. vessel size is primarily responsible for texture, however, in a wood with large rays and vessels of moderate size or small size, coarse texture may ensure from large rays alone. the classification given in table 2 and ray information studied serve to indicate roughly the basis of classification. ruwanpathirana/journal of tropical forestry and environment vol. 4, no 01 (2014) 1-13 5 table 2: classification of wood texture. type of wood texture average tangential diameter of the vessel (µm ) fine textured less than 100 microns medium textured 100 to 200 microns coarse textured more than 200 microns 2.9 wood working properties wood working properties such as sawing, nailing, sanding and polishing were determined with the assistance of an experienced carpenter. accuracy of the results was maintained by doing repeated tests. in order to obtain an idea of sawing ability, air seasoned, uniform thickened mature heartwood potions were also tested by the experienced carpenters. in order to depict data clearly, results were grouped into three categories as easy, moderate and difficult. for nailing, the air seasoned mature heartwood samples in dimensions of 132×7.5×12 mm were used. the nailing was done on cross section surface 13 mm interior to the border. results were categorised into three groups as easy, moderate and difficult. sanding data were obtained through number 320 sanding paper and results were categorized as very good, good and moderate. final finishing property also classified as very good, good and moderate. 2.10 islandwide survey an islandwide questionnaire survey was conducted to gather information from timber users who have experience on timber durability particularly using timber in outdoor uses. 3. results table 3, 4, 5, and 6 present in the following sections illustrate all wood properties studied in this research work. table 3: wood density and density property classes, modulus of elasticity, modulus of rupture and compression parallel to grain of the selected timber species. no species density class density at 12% m.c. modulus of elasticity (nmm -2 ) modulus of rupture (nmm -2 ) compression parallel to grain (nmm -2 ) 1 acacia malanoxylon hd 738 11,811 90 45 2 michelia champaca ld 500 8,503 64 32 3 eucalyptus grandis md 595 9,827 74 37 4 alstonia macrophylla hd 690 11,150 84 43 5 dipterocarpus zeylanicus hd 762 12,142 92 47 6 bridelia retusa vhd 850 13,500 103 50 7 khaya senegalensis md 603 9,932 75 37 8 azadirachta indica hd 714 11,481 87 44 9 adina cordifolia hd 666 10,819 82 41 10 artocarpus heterophyllus md 625 10,250 78 39 ruwanpathirana/journal of tropical forestry and environment vol. 4, no 01 (2014) 1-13 6 11 terminalia arjuna hd 714 11,481 87 44 12 homalium zeylanicum hd 738 11,811 90 45 13 melia dubia ld 400 6,050 40 20 14 swietenia macrophylla md 609 10,025 76 38 15 madhuca longifolia vhd 900 14,250 115 58 16 eucalyptus microcorys vhd 875 13,719 105 53 17 albizia saman md 585 9,694 73 36 18 hevea brasiliensis md 540 9,059 68 34 19 tectona grandis hd 720 11,550 88 43 20 toona ciliata ld 500 850 60 30 * ld = low density, md = medium density, hd = high density, vhd = very high density. table 4: wood working properties, seasoning and wood shrinkage in twenty timber trees. no scientific name seasoning & shrinkage working properties 1 acacia malanoxylon must be thoroughly seasoned. seasons well. shrinkage green to oven dry is 6%. easy to work with hand and machine tools. excellent polishing properties. glues & stains well. poor nailing. splits easily & preboring is recommended. 2 michelia champaca seasoning is not easy as the timber is liable to split especially if left in the log form. shrinkage green to oven dry is 8.4%. easy to saw & works to a smooth surface. good polishing. 3 eucalyptus grandis difficult to season, cupping may occur in back-sawn boards, but can be removed by reconditioning treatment. shrinkage green to 10% moisture content is 6.03%. young trees work easily. old material may produce certain surface wooliness & tendency to split. free from defects. good polishing. tends to split in nailing. 4 alstonia macrophylla green conversion & immediate seasoning give best results. shrinkage green to 10% moisture content 8.92%. sawing & nailing are somewhat difficult. easy to sanding & takes a good polish. 5 dipterocarpus zeylanicus seasoning is somewhat difficult. air drying is needed before kiln drying. shrinkage green to 10% moisture content is 6.63%. easy to sawing. somewhat easy to nailing. easy to sanding & finishing is somewhat good. 6 bridelia retusa seasons defects sometimes appear & hence green conversion & prompt stacking for slow drying is recommended. shrinkage green to 10% moisture content is 5.45%. saws and machines well & works to a smooth surface. easily worked with hand tools. 7 khaya senegalensis seasons well. shrinkage green to 10% moisture content 4.78%. easy to sawing, nailing & sand papering. good finish when polished. filling materials should be used. ruwanpathirana/journal of tropical forestry and environment vol. 4, no 01 (2014) 1-13 7 8 azadirachta indica seasons well. shrinkage green to 10% moisture content is 2.48%. somewhat difficult to sawing. easy to nailing & sand papering. poor finish when polishing (good for staining). 9 adina cordifolia seasons well. shrinkage green to oven dry is 10.2%. shrinkage green to 10% moisture content is 5.88%. easy to sawing & sand papering, slightly difficult to nailing, good finish after polishing. 10 artocarpus heterophyllus seasons easily. shrinkage green to 10% moisture content is 1.62%. easy to saw & work. finish well particularly if fillers & sealers are used. polish with a high lustre. 11 terminalia arjuna seasons well. should dry slowly. large timber prone to crack split & bend. shrinkage green to 10% moisture content is 5.79%. difficult to sawing & nailing. sand papering is easy. good finish when polishing. 12 homalium zeylanicum somewhat difficult to seasons. shrinkage green to 10% moisture content 14.4%. saws and works easily. takes a good polish. 13 melia dubia seasons easily. shrinkage green to 10% moisture content is 6.06%. easy to saw & work, but difficult to obtain a smooth finish on the account of its softness. 14 swietenia macrophylla seasons well & easily without much checking or distortion. kiln drying satisfactorily when moderate scheduling. shrinkage green to 10% moisture content is 2.93%. saws, planes & moulds easily, finish to a smooth surface. wood takes an excellent polish. gluing & nailing are good. discolorations in contact with iron, copper & brass. 15 madhuca longifolia seasons well. if converted green, log tend to split at the ends if left unconverted. shrinkage green to 10% moisture content is 8.65%. sawing is somewhat easy. difficult to nailing & easy for sand papering. good finish when polished. 16 eucalyptus microcorys somewhat difficult especially with fast grown timber. shrinkage green to 10% moisture content is 9.77%. easy to saw. difficult to nail, sanding & polishing. difficult to obtain a good polish. 17 albizia saman seasons well. shrinkage green to 10% moisture content is 9.18%. easy to sawing, nailing & sand papering. 18 hevea brasiliensis seasons well. shrinkage green to 10% moisture content 7.69%. easy to sawing, nailing & sand papering. good finish when polishing. 19 tectona grandis once seasoned "movements" are very little. shrinkage green to oven dry is 9.9%. not difficult to saw or work, but care is need in working as the timber is somewhat brittle. 20 toona ciliata seasons easily but radial checks & heart-shakes develop in the log. careful stacking is required to prevent warping. shrinkage green to 10% moisture content is 9.85%. saws & works easily with good finishing qualities. ruwanpathirana/journal of tropical forestry and environment vol. 4, no 01 (2014) 1-13 8 table 5: durability of wood , wood texture and heartwood colour. no scientific name durability heart wood colour and wood texture 1 acacia malanoxylon durable. resistant to effective preservative treatments. brown or shaded of brown (iawa). rich reddish brown to nearly black banded with golden brown or red. even, medium to even textured. 2 michelia champaca durable. easy to medium ability to apply preservative treatments. yellow or shaded of yellow (iawa). light yellowish brown to olive brown. lustrous. even & medium textured. 3 eucalyptus grandis moderately durable. somewhat difficult to apply preservative treatments. red or shaded of red (iawa). white to pink or light to dark red brown with a pink tinge, depending on age and area of origin. medium or coarse textured. 4 alstonia macrophylla moderately durable. easy to apply preservative treatments. yellow or shaded of yellow (iawa). no distinct heartwood. cream colour. medium, even textured. 5 dipterocarpus zeylanicus moderately durable. somewhat difficult to apply preservatives. red or shaded of red (iawa). light pinkish brown on first exposure ageing to reddish brown. even & coarse textured. 6 bridelia retusa durable. difficult to apply preservative treatments. brown to shaded of brown (iawa). dark to olive brown sometimes with darker streaks. medium & fairly even textured. 7 khaya senegalensis moderately durable. easy to apply preservative treatments. red or shaded of red (iawa). even pink colour to reddish brown (mahogany brown). medium & coarse textured. 8 azadirachta indica durable. difficult to apply preservative treatments to heartwood. red or shaded of red (iawa). red when first exposed darkening to reddish brown & then resembling mahogany. medium to somewhat coarse textured. 9 adina cordifolia moderately durable. easy to apply preservative treatments. yellow or shaded of yellow (iawa). citron yellow when first exposed, turning pale yellowish or reddish brown with age. fine and even textured. 10 artocarpus heterophyllus durable. resistant to effective preservative treatments. yellow or shaded of yellow (iawa). yellow or lemon yellow gradually turning to a rich mahogany brown, very old wood to a warm vandyke brown. coarse textured. 11 terminalia arjuna durable. easy to apply preservative treatments. brown to shaded of brown (iawa). olive brown streaked with dark blackish lines. coarse and even textured. 12 homalium zeylanicum durable. difficult to apply preservative treatments. brown to shaded of brown (iawa). yellowish brown to yellowish red on first exposure. even & fine textured. ruwanpathirana/journal of tropical forestry and environment vol. 4, no 01 (2014) 1-13 9 13 melia dubia non-durable. easy to apply preservative treatments. red or shaded of red (iawa). light pink to light red, when first exposed ageing to reddish brown. coarse & somewhat uneven textured. subject to a grey stain. 14 swietenia macrophylla durable. resistant to effective preservative treatments. red or shaded of red (iawa). reddish, pinkish, salmon coloured or yellowish when fresh, darkening to deep red or brown with age. moderately fine to rather coarse. 15 madhuca longifolia durable. difficult to apply preservative treatments. red or shaded of red (iawa). dull, dark red, ageing to dull reddish brown streaked with light brown lines. coarse & even textured. 16 eucalyptus microcorys durable. resistant to effective preservative treatments. yellow or shaded of yellow (iawa). pale or yellowish brown or straw colour. moderately coarse & even textured. 17 albizia saman moderately durable. resistant to effective preservative treatments. brown to shaded of brown (iawa). golden brown to dark brown. coarse textured. 18 hevea brasiliensis non-durable. easy to apply preservative treatments. brown to shaded of brown (iawa). difficult to distinct from the softwood. white colour when first exposed, turn into pale brown when ageing. pink tinge present. coarse and even textured. 19 tectona grandis durable. difficult to apply preservative treatments. brown to shaded of brown (iawa). golden brown which darkens with age. coarse and uneven textured. 20 toona ciliata moderately durable. difficult to apply preservative treatments. red or shaded of red (iawa). light brick red when first exposed, ageing to a rich reddish brown. moderately fine & somewhat uneven textured. table 6: uses twenty timber species. no scientific name uses 1 acacia malanoxylon furniture, boats, cabinets, plywood, doors & window frames, fittings in banks, railway carriages, gun stocks, decorative works. 2 michelia champaca reapers, ceiling spacers, door & window sashes, partition frames, floor boards, buildings, cheap furniture, valance boards. 3 eucalyptus grandis general construction, bridges, poles, posts, furniture, paneling, sleepers. 4 alstonia macrophylla general construction, toys, match-boxes, posts, cheap furniture, coffins, carving, blackboards, transmission poles. ruwanpathirana/journal of tropical forestry and environment vol. 4, no 01 (2014) 1-13 10 5 dipterocarpus zeylanicus reapers, ceiling spacers, fascia boards, door frames, partition frames, cheap furniture, treated sleepers, transmission poles, construction, underwater work, piles, boards, scaffoldings, rafters, beams. 6 bridelia retusa rafters, purlins, ridge hips, ceiling joists, wall plates, beams, reapers, buildings, furniture, agriculture implements, drums, carts, cart shaft. 7 khaya senegalensis boxes, posts, light construction, ceiling boards, door & window sashes. 8 azadirachta indica furniture, paneling & decorative work, rafters purlins, ridges hips, ceiling joists, wall plates, reapers, buildings, panels, carvings, bottom of drawers. 9 adina cordifolia general utility timber, purlins, ridge hips, reapers, railing spacers, door &window sashes, furniture, carvings, fine turnery wood, ornamental caskets, picture frames, brush-backs. 10 artocarpus heterophyllus house building, furniture, carriages, cabinet making, musical instruments, boats, building, casks. 11 terminalia arjuna beams, rafters, purlins, ridge hips, ceiling joists, wall plates, furniture, construction, bridges. 12 homalium zeylanicum beams, rafters purlins, ridges hips, ceiling joists, wall plates, flooring, buildings, boats, oars, stair cases, brush backs, posts. 13 melia dubia ceiling boards, paneling & packing cases, cigar boxes. 14 swietenia macrophylla door &window frames, partition frames, furniture, cabinets, paneling & decorative work, railway carriages, piano cases, veneers. 15 madhuca longifolia heavy construction, agricultural implement, reapers, ceiling spacers, door &window frames, partition frames, heavy construction, posts, beams, boats, bridges. 16 eucalyptus microcorys piles, poles, posts, flooring, sleepers, transmission poles, heavy construction work, excellent for dance floors. 17 albizia saman beams, rafters, purlins, ridges hips, ceiling joists, wall plates, furniture, paneling, flooring. 18 hevea brasiliensis partition frames, ceiling boards, furniture, light construction, brush handles. 19 tectona grandis ship building, high class joinery, flooring, interior fittings, door & windows frame & sashes, stair cases, fancy goods, veneers, railway carriers, beams, rafters purlins, ridges hips, ceiling joists, wall plates, reapers, ceiling spacers, furniture, railway carriages. 20 toona ciliata furniture, paneling, cigar boxes, racing boats, musical instruments. 4. discussion it can be understood that when popular or well known timber is not available or not affordable due to high cost, another timber species is sought often on the basis of comparability with that formerly used. in this timber selection process, the cost involved is often considerable and users may be reluctant to face risk accepting the unknown timber species. this situation can be altered by providing guidance on property needs for the appropriate to end-use. the end-use property classification given in this paper provides the means to make an objective assessment of the suitability for a particular purpose of timber use. however, this suitability of timber depends on the combined cost of the selected timber and additional cost involved for processing (e.g. ruwanpathirana/journal of tropical forestry and environment vol. 4, no 01 (2014) 1-13 11 preservation). this cost is compared with the cost of a timber which is not required for additional processing. thelandersson & hansson (1999) stated that wood has significant variations in its properties both between and within timber elements. variations in strength properties may be species-specific, age-dependent and environmentally responsive. therefore it is suggested to conduct more research work in this field based on more timber samples representing of the entire population. understanding physical properties, mechanical properties, durability and gross features of various timber species are very much important in selecting timbers for various purposes. correct use of timber always increases the life time of the final product, whether it is high class furniture or a simple craft work. this paper provides most important wood properties facilitating to select timber species according to end-use or end use requirement of twenty sri lankan timber species. in general, the proposed property classification in this paper can be categorised as (i.) end-use property classification for building construction, (ii.) end-use property classification for furniture and joinery (iii.) end-use property classification for light construction and (iv.) end-use property classification for miscellaneous uses. it is an imperative exercise to find out the most influential wood properties for each category of end use property classification given here with. very high density timber such as madhuca longifolia and eucalyptus microcorys, studied in this research work are often chosen for heavy construction work due to not only its high strength property but also good performance experience in use for centuries. it was found that timber density of m. longifolia and e. microcorys are 900 kgm -3 and 875 kgm -3 at 12% m.c respectively. in addition, both species showed high values of mechanical properties such as modulus elasticity, modulus of rapture and compression parallel to grain (table 3). both timber species demonstrated effective resistant to boron treatment when application of preservatives was done. furthermore, results of grave yard test showed that both timber species can be classified as durable timber. as far as wood working properties are concerned, sawing is easy and nailing is difficult for both species. working properties like sanding and polishing did not demonstrate such similarity in m. longifolia and e. microcorys. these finding might be used to define the standard for quality requirement and quality level for end-use property classification for construction timber. in this classification, some important quality requirements like seasoning defects, dimensional movement etc. can also be included for further improvement. further it is recommended that preferable property level of timber for major end-uses should be studied in future research. end-use property classification for furniture and joinery category which involves end-use products like window joinery, door and window frames, flooring and cabinet work etc. can be derived for the construction timber category mentioned in the earlier section. acacia malanoxylon, adina cordifolia, artocarpus heterophyllus, terminalia arjuna, swietenia macrophylla, tectona grandis and eucalyptus grandis have proven timber quality complying with technical requirements, needed for end-use category of furniture and joinery. when variations of timber density of furniture and joinery category were analysed it was found that all the species can be categorised as medium to high density. this group of timber has somewhat lower density than to construction timber category. results in table 4 show that the timber in this category seasons well and demonstrated comparatively better working properties than those in ruwanpathirana/journal of tropical forestry and environment vol. 4, no 01 (2014) 1-13 12 the construction category. according to iawa (1989) classification, the heartwood colour of furniture category timber consists of different wood colour. a. malanoxylon, t. arjuna and t. grandis have brown or shaded brown colour and s. macrophylla and e. grandis have red or shaded red colour followed by a. cordifolia and a. heterophyllus with yellow and shaded yellow. according to this finding, property requirements and level for the end-use classification for furniture and joinery might be derived from these research findings and further development can be made with increased number of timber species. in this direction, we have initiated a research program to collect wood properties of 235 sri lankan timbers. the publication of “sri lankan timber: timber properties and its uses” covering 100 timber species is now in the press and it will be helpful to those who are willing to continue research in this regard. among many timber varieties used for light construction work in sri lanka, m. champaca, m. dubia , t. ciliate and h. brasiliensis are the most popular timber species. it can be assumed that wood properties in this study might influence mainly for the end-use application. therefore by recognising these influential wood properties, it was possible to list out major property requirements and level for end-use property classification. according to table 3, all the above timber species belong to light to medium density categories and having low mechanical properties. both h. brasiliensis and m. dubia are non-durable and both timber can be preserved easily. according to the results of the boron treatment (table 5), m. champaca and t. ciliate were classified as easy/medium category and difficult category respectively. all three species which were tested for working properties showed almost similar results indicating that working properties such as sawing and nailing are easy. major property requirements for end-use property classification for light construction can be identified by these results. end-use property classification for miscellaneous uses might be developed for the specific end-use application. for instance, m. longifolia timber is perfect for storing boxes of paddy seeds or container because this timber is capable to repulse pests or insects that use to come and destroy the paddy yield. some timber species such as b. cordifolia is highly demanded for manufacturing of vats. it is believed that b. cordifolia timber can enhance the quality of liquor by absorbing unfavorable matters and improve the taste and smell. timber like b. retusa and v. pinnata possess special wood quality which helps to persist the timber in ground contact environment without getting deterioration. d. zeylanicus is eminently suitable for under-water work. e. microcorys is regarded as one of the best timber for dance floors. this specialty and causative factors of timber must be explored and documented in order to prepare end-use property classification for miscellaneous use. finally, if there is a timber property classification, i.e., requirement and property level for major end-uses as discussed in this paper and comprehensive information on wood properties of sri lankan timbers is available, then the timber industry will be able to define the technical information of timber which they need for their end-use applications. subsequently the timber supplier can easily quote and supply the most suitable timber variety which is complying its technical performance with the requirement of end-use. ruwanpathirana/journal of tropical forestry and environment vol. 4, no 01 (2014) 1-13 13 references hatharasinghe, s.m., 2013. community awareness of timber in sri lanka. bsc dissertation, university of ruhuna, sri lanka. iawa committee (1989). iawa list of microscopic features for hard wood identification. iawa bulletin (n.s.)10, netherlands. ruwanpathirana, n.d., 2012. sustainable utilization of timber resources in sri lanka. soba, ministry of environment, sri lanka, pp.56-70. ruwanpathirana, n.d, 2014. sri lankan timber species: wood properties and its uses, ministry of envirnment, sri lanka. thelandersson, s., hansson, m., 1999. reliability of timber structural system-effects of variability and inhomogeneity. lund university of technology, sweden. withana, m. h., 2013. classification of timber species in sri lanka and developing a model for price determination. bsc dissertation, university of ruhuna, sri lanka www.timber.lk (forestry education web site), 100 timber species in sri lanka. accessed 15 th may 2014. microsoft word 6 katupotha katupotha /journal of tropical forestry and environment vol. 3, no. 01 (2013) 42-54 42 palaeoclimate change during glacial periods: evidence from sri lanka j. katupotha department of geography, university of sri jayewardenepura, nugegoda, sri lanka date received: 24-11-2012 date accepted: 16-02-2013 abstract in the earth’s history, there were five major glaciations, namely, huronian (2,300 ma), cryogenianor sturtian-varangian(850-635 ma), andean-saharan (460-430 ma, karoo (360-260 ma) and the quaternary (2.58 ma to present) that occurred between 2,300 ma and 0.0114 ma. it is revealed that gondwanaland emerged between the huronian glaciation (2300-2100 ma) in the paleoproterozoic era and the andean-saharan glaciation (460-420 ma) in the early paleozoic era. during this time, most continental land masses were clustered in the southern hemisphere, and sri lanka was part of the gondwanaland landmass comprising present day africa, madagascar, india and antarctica. within the ordovician (485.4-445.2ma) to permian periods (299.0-254.2 ma) there were signs of the breaking up of gondwanaland resulting in the severing of india and sri lanka together and subsequently sri lanka from india. by end of the permian period (260 ma) karoo glaciation had ended and the present mannar basin developed within a deep canyon (about 4-7 km deep) on the precambrian basement. although the island of sri lanka presently lies in the indian ocean between 5 º 52´n-9 º 54´n and 79 º 30´e-81 º 55´e, to the southwest of bay of bengal and southeast of arabian sea, it was positioned within 67 º s-65 º s and 34 º e-43 º e during the lower and middle jurassic era (201.3-166.1 ma). huge rocky blocks (erratic boulders) have been transported to different places by continental ice sheets due to climatic changes in the permian, triassic and jurassic periods, but erratic pebbles (2 to 8 cm or more in size) and streams fed deposits have been transported by glacifluvial processes. these glaciofluvial processes occurred on four occasions during the jurassic period and eocene, miocene and pliocene epochs on sri lankan landmass, which fallowed the climatic changes and sea level fluctuations that broke up the sedimentary beds, initiating establishment of the present topography and structural configuration. as a result, the earlier sedimentary deposits were obliterated from greater part of sri lanka. during the quaternary period the erosional rate increased and the resultant erratic boulders along with glaciofluvialdeposits can still be found on “planated surfaces”of sri lanka. 1. introduction from the time of initial accretion and differentiation (ca. 4560 ma) to the first appearance of abundant hard-bodied fossils, the precambrian super eon spans 88 percent of earth history (felix et al., 2004).sri lanka is a tropical island positioned between 5 º 50´n-9 º 55´n and 79 º 30´e-81 º 55´e, southwest bay of bengal and southeast arabian sea in the indian ocean. although sri lanka became a separate landmass during the triassic-jurassic period (208.5-201.3 ma), its history goes back to the achaean eon of the precambrian super eon that is divided into six eons, with boundaries defined by what can be considered first-order “watersheds” in the evolution of the earth (felix et al., 2004). *correspondence: katupotha@gmail.com tel: +94 71 8011540 fax: +94 11 5524530 issn 2235-9370 print / issn 2235-9362 online ©2013 university of sri jayewardenepura katupotha /journal of tropical forestry and environment vol. 3, no. 01 (2013) 45-57 43 sri lankan rocks have been documented to be late archaean to early proterozoic (3,200 2,400 ma) based on ages of detrital grains zircons obtained from highland/southwestern complex (h/swc) rocks. it is revealed that these rocks have a relationship with precambrian events, and therefore to be the foundation rocks or basement rocks of sri lanka (hölzlet al. 1991; kröneret al. 1991). by the paleoproterozoic era (2,050 1,800 ma), the rugged high ground occupying the highland complex (hc) of sri lanka (cooray 1994) became characterized by a nw-se and ne-sw trending sequence of highgrade metasediments and granuliticorthogneisses. likewise, during the mesoproterozoic era (1600-1200 ma), orthogneisses of the vijayan complex (vc) were intruded between 1,040-1,030 ma and orthogneisses of the wanni complex (wc) were intruded between 1,100-670 ma. moreover, by the neoproterozoic era between 610 and 550 ma, the high-grade regional metamorphism of the hc, vc and wc took place within ultra-high temperature metamorphic rocks (braun, 2003). all these proterozoic rocks are the basement rocks of sri lanka. in the earth’s history, there were five major glaciations, namely, the huronian, cryogenian or sturtian-varangian, andean-saharan, karoo (carboniferous and permian period) and the quaternary that occurred between 2,300 and 0.0114 ma (ics 2009). it is accepted that gondwanaland emerged between the huronian glaciation (2,300-2,100 ma) in the paleoproterozoic era and the andean-saharan glaciation (460-430 ma) in the early paleozoic era. wanless and cannon (1966) reported the events of late paleozoic glaciation from india and pakistan, africa, south america, australia, antarctica, madagascar and falkland islands. during these glacial times, most of the continental land masses mentioned above were clustered in the southern hemisphere, and the landmass of sri lanka remained joined to the landmass of africa-madagascar-india that was joined to antarctica. although the present landmass of sri lanka lies southwest of bay of bengal and southeast of arabian sea, it was positioned within 67 º s-65 º s and 34 º e-43 º e during the lower and middle jurassic era (201.3-166.1 ma). climatic changes in the permian, triassic and jurassic periods huge rocky blocks (erratic boulders) have been transported to different places by continental ice sheets. likewise erratic pebbles, smaller stones from 2 to 8 cm or more, andstreams fed deposits have been transported by glacifluvial processes (table 1). this paper proposes that these glaciofluvial processes that occurred on four occasions namely, the jurassic period and eocene, miocene and pliocene epochs due to geologicand climatic changes and sea level fluctuationsbroke up the prevailing glaciofluvial sedimentary beds, giving rise to the present topography comprising, “planated surfaces”, relict erratic boulders and ice-rafted or streams fed deposits. quesnelet al. (2012) have proposed a geomorphologic classification of planation surfaces and inferred scenarios of vertical deformation and morphogenetic evolution by applying the planation surface concept, previously used for stable cratonsof western africa, australia and brazilguyana which endured glacial times. this is the first attempt to postulate that sri lanka had endured glacial climate as revealed by the incidences of erratic boulders, erratic pebbles and streams fed deposits. both erratic pebbles and stream fed deposits weredeposited from melt-water of the karoo (carboniferous permian period, 360-260 ma) glaciers since the middle triassic to the early eocene period (247.2-56.0 ma). by early eocene time, sri lanka was located between 18-24 o s and 63-66 o e (table 1). in this effort, information gathered from detailed investigations of erratic boulders located along the coastal belt in the eastern province (second planated surface) and erratic boulders and streams fed deposits of the kurunegala district, northwestern province (second and third planated surfaces) further validated glaciation and climate change. 2. methodology in the earth’s history, glacial and interglacial periods have played a significant role in the evolution of continentsand palaeoclimate together with fauna and flora, ice-rafted and streams fed deposits etc.poulsenet al (1977) present evidence that late paleozoic tropical climate responded to katupotha /journal of tropical forestry and environment vol. 3, no. 01 (2013) 42-54 44 gondwanan de-glaciation. there are also many geological, geomorphological, palaeontological and sedimentological evidences that can be found on land (from continents) and from oceanic sediment cores (steiner and wallick 1992). the prime motivation for writing this paper is to suggest a process for the evolution of its major planated surfaces and associated climate changes as a consequence of palaeodeglaciation revealed by the occurrence of glaciofluvial deposits.in this effort, information regarding size and dimensions of erratic boulders was gathered from detailed investigations during the period from november 2011 to march 2012 and september 2012 from in many localities within colombo, kurunegala,trincomalee, batticaloa and ampara districts. 3. results and discussion the cyclic sedimentary sequences located in low latitudes in continental areas are interpreted as results of frequent changes in global sea levels associated with palaeo glacial cycles. glacial cycles and variations in sea level are documented in oxygen-isotope and pco2 variations (horton et al. 2012). due to such changes much of the southern hemisphere was covered by ice as glaciers pushed northward by upper permian time (298.9-279.3 ma). coal was produced in both equatorial rainforests and in temperate forests during the warmer "interglacial" periods (table 1). likewise, the equatorial rainforest disappeared as deserts spread across central pangaea during the middle and upper permian periods. although the southern ice sheets were gone, an ice cap covered the north pole. likewise, rainforests covered south china as it crossed the equator. sea levels in the permian period remained generally low, and near-shore environments were limited by the collection of almost all major landmasses into a single continent called pangaea (ics 2009). table 1: showing the climate changes and other significant events in relation to glacial periods. the symbol • denotes events in sri lanka. era period epoch major events in sri lanka (sl) are in italics start (ma bp) quaternary holocene the last glacial period ends; the salient feature is rise of human civilization. quaternary ice age recedes, and the current interglacial begins. the period of cold climatic conditions and drought, which name as younger dryasoccurred between approximately 12,800 and 11,500 years bp. sahara forms from savannah, and agriculture begins, allowing humans to build cities. • post-glacial sea level rise, drowning of continental shelf, sea level was at least 1.5m or more above from present level. unconsolidated sandy beaches and dune deposits, beach rock, lagoon and estuarine clays, alluvium, buried and emerged coral reefs were formed (katupotha 1988a; 1988b; 1988c and 1995). • streams fed deposits and other fluvial deposits flowed from central highland to coastal zone (to second planated surface). • the first planated surface submerged by sea water, and now exists submerged. (this surface is designated assubmerged plateau by sommerville, 1907 and submerged peneplain by deraniyagala, 1958. 0.0114 pleistocene little ice age (stadial) causes brief cooling in northern hemisphere from 1400 to 1850 ade. atmospheric co2 levels start creeping from 100 parts per million volume (ppmv) at the end of the last glaciation to the current level of 385 ppmv, causing some sources, global warming and climate change, possibly from anthropogenic sources. 0.01170.126 (upper) katupotha /journal of tropical forestry and environment vol. 3, no. 01 (2013) 45-57 45 flourishing and then extinction of many large mammals (pleistocene mega-fauna). evolution of anatomically modern humans. • stranding evidence of sea level fluctuations, sand dunes, gravel deposits, formation of red beds, laterite, nodular ironstone (katupotha 1995; cooray 1984). • erratic pebbles, stream fed deposits and other terrestrial deposits flowed from central highland to coastal zone (to second planated surface). • sl assuming present position between 5º 52´n-9º 55´n and 79º 30´e-81º 55´e. 0.781 (middle) 1.806 2.588 (lower) neogene pliocene intensification of present icehouse conditions, present (quaternary) ice age begins roughly 2.58 ma; cool and dry climate. australopithecines, many of the existing genera of mammals, and recent mollusks appear. homo habilis appears. • marine colloidal sedimentation in northwestern sl. 3.6005.332 miocene moderate icehouse climate, punctuated by ice ages; orogeny in northern hemisphere. widespread forests slowly draw in massive amounts of co2, gradually lowering the level of atmospheric co2 from 650 ppmv down to around 100 ppmv . . • the puttalam-jaffna limestone in the northwest and minihagalkanda beds in the southeast were deposited. by the tortonian stage(11.62-7.246 ma) of the miocene period, sri lanka had located itself at 4 º n 8 º n and 77 º e 79 º e. • by mid miocene (15.97-13.82 ma), sri lanka was positioned between 0.30 º n 4 º .30’s and 73 º e 76 º e. erratic boulders, erratic pebbles and stream fed deposits deposited at random on second and third planated surfaces. 23.03 7.246 paleogene oligocene warm but cooling climate appeared on the earth, moving towards icehouse; rapid evolution and diversification of fauna, especially mammals. major evolution and dispersal of modern types of flowering plants (ics 2009). • by oligocene period, central highland was covered by an ice cap, glaciers on second and third planated surfaceswere melting. 33.9 28.1 eocene moderate, cooling climate. re-glaciation of antarctica and formation of its ice cap; and the icehouse earth climate that would follow it to this day. lowering of atmospheric carbon dioxide from 3800 ppmv down to 650 ppmv (ics 2009). • 37.2 ma, sl resided as an island within 9 o -13 o s and 66 o – 69 o e. himalayan orogeny began between 52 and 48 ma. • at that time sl was between 18 o -24 o s and 63 – 66 o e. • possibility of the fourth planated surface (central highlands) being covered by glaciers. 56.0-38.0 paleocene alpine orogeny in europe and asia begins. indian subcontinent collides with asia 55 ma, himalayan orogeny starts between 52 and 65.5 58.7 katupotha /journal of tropical forestry and environment vol. 3, no. 01 (2013) 42-54 46 48 ma (ics, 2009). • sl positioned between 31 o s-34 o s and 55 o e-58 o e mesozoic cretaceous break up of gondwana. beginning of laramide and sevier orogenies of the rocky mountains. atmospheric co2 close to present-day levels. • between 100.5 ma and 72.1 ma (upper cretaceous) sl moved further north and east (45 º s-50 º s and 53 º e-56 º e) rotating northerly. • around 125.0-113.0 ma sl was located within 45 º s 50 º s and 53 º e-56 º e. between 136 ma and 130 ma in early cretaceous, sl rotated anticlockwise from ene-wsw to ne-sw; sl located around 64 o s=66 o s to 33 o e-38 o e.at some stage during the cretaceous period (145.0=70.6 ma) more than 850m thick sandstones were deposited in the mannar basin. • evolution of “post-gondwana” highland landscapes (king 1962). 100.5 72.1 145.5 113.0 jurassic upper breakup of pangaea into gondwana and laurasia. nevadan orogeny in north america. rantigata and cimmerian orogenies taper off. atmospheric co2 levels 4-5 times the present day levels (1200-1500 ppmv, compared to today's 385 ppmv). • sl detached from the southern supercontinentgondwanaland. the indian ocean began to open up. india and sri lanka’s landmass separated from the australia and antarctica/australia plate. • during the upper jurassic period sl was positioned within 65 o s67 o s and 32 o e-36 o e. tabbowa beds (generally (arkoses) and andigama-pallama beds (arkoses and carbonaceous shales with thin coal slivers) were formed locally onshore within faultbounded basins. • sl emerged as a separate landmass. 163.5 152.1 middle 174.3 161.1 lower 201.3182.7 triassic upper landmasses unite into supercontinent pangaea, creating the appalachians. end of permo-carboniferous glaciation. permian-triassic extinction event occur 251 ma: 95% of life on earth becomes extinct, including all trilobites, graptolites, and blastoids. climate was generally hot and dry. formed typical red bed sandstones and evaporites. large size of pangaea limited the moderating effect of the global ocean. the permian–triassic extinction event (great dying) occurred 251.4 ma ago (ics, 2009). 235.0 208.5 middle 247.2 242.0 lower 252.0 251.2 paleozoic permian sea levels in the permian remained generally low, and near-shore environments were limited by the collection of almost all major landmasses into a single continent pangaea (ics 2009). 254.2 299.0 carbonifer ous/pennsylvanian uralian orogeny in europe and asia. variscan orogeny occurs towards middle and late mississippian periods. 323.2 303.7 carbonife rous/mississippian coal-forming coastal swamps. glaciation in east gondwana. tuhua orogeny in new zealand tapers off. 358.9 330.9 devonian "old red continent" of euramerica. beginning of acadian orogeny for anti-atlas mountains of north africa, and appalachian mountains of north america, also the antler, variscan, and tuhua orogeny in new zealand. 419.2 372.2 katupotha /journal of tropical forestry and environment vol. 3, no. 01 (2013) 45-57 47 siluian beginning of caledonian orogeny for hills in england, ireland, wales, scotland, and the scandinavian mountains. also continued into devonian period as the acadian orogeny, above. taconic orogeny tapers off. lachlan orogeny on australian continent tapers off. 443.4 423.0 ordovician gondwana emerges. petermann orogeny on the australian continent tapers off (550-535 ma). ross orogeny in antarctica. atmospheric co2 content roughly 20-35 times present-day (holocene) levels (6000 ppmv compared to today's 385 ppmv) and ice age at end of period (ics, 2009). • from ordovician (488.3-445.6ma) to permian (299.0 253.8 ma) there were breaking up signs of gondwanaland, including between sri lanka and india. • present mannar basin developed as a deep canyon (about 4 km deep) on the precambrian basement. 485.4 445.2 cambrian 542 – 496 ma, the gondwanaland emerges. most continental land masses were clustered in the southern hemisphere (ics 2009). • sl remained joined with the landmass composed of africa, madagascar" india and antarctica. joining east gondwanaland to west gondwanaland (ics 2009). 541.0 – 489.5 source: see references cooray 1984; ics 2009 (retrieved 2009-09-25); katupotha 1988a, 1988b, 1988c and 1995; king 1962; sommerville, 1907 and deraniyagala, 1958. in sri lanka, nearly 90% of its rock types are composed of crystalline precambrian metamorphic rocks. they are subdivided as highland complex, wanni complex and vijayan complex and other small divisions (cooray, 1984, 1994; hölzlet al. 1991, kröneret al. 1991). meta-igneous rocks (charnockites, hornblende-biotite gneiss, migmatitic and quartzofeldspathic rocks) and metasedimentary rocks (quartzites, marble/dolomite and garnet-sillimanite-graphite schist) are major rock types of the highland complex. the vijayan complex lies east of the highland complex. it is composed of metamorphosed granitoids, charnockitic gneisses, migmatites, microcline-bearing quartzofeldspathic rocks, amphibolite and/or biotite gneiss. the wanni complex located west of the highland complex is composed of rock types more or less similar to those of the vijayan complex. in addition, a small unit named “kadugannawa complex” composed of amphibolite or hornblende-biotite gneisses and migmatitesis located in the central part of the country. the other remaining rocks (~10%) consist of jurassic sandstones, shales and mudstones, some exposed in faulted basins at tabbowa and andigama, and miocene limestone lying unconformably on the precambrian basement of the north, northwestern and southeastern coastal belts (cooray, 1984; katupotha and dias, 2001). geologically, the jurassic period is extremely important to sri lanka. prior to jurassic, at the end of the paleozoic the earth's surface was characterized by a relatively simple landmass configuration with three main continents (gondwanaland, laurasia and angaraland) coalescing to form the pangean supercontinent. the oceanic domain was defined in its major part by panthalassa and partially by the tethys. no major geographic rearrangement of continents and oceans has been documented for the permian-triassic transition and for the lower triassic, except for the northward motion of entire pangaea (galfetti, et al, 2007). during the triassic which extends about 252.2 to 208.5ma and global climate was warm during the upper triassic. there was no ice at either north or south poles. warm temperate conditions extended towards the poles. the pangaea mega-monsoon was in full swing during the lower and middle jurassic (jinnan and parrish 1999). the interior of pangaea was very arid and hot. deserts covered what is now the amazon and congo rainforests. china, surrounded by moisture bearing winds was lush and verdant. during the katupotha /journal of tropical forestry and environment vol. 3, no. 01 (2013) 42-54 48 upper jurassic (163.5-152.1 ma) the global climate began to change due to the break-up of pangaea. the interior of pangaea became less dry, and seasonal snow and ice frosted the polar regions. by lower to middle jurassic (201.3-166.1ma), sri lanka emerged as a separate landmass positioned within 52 o s-55 o s and 17 o e-22 o e. sri lanka reached its present position at 5º 52´n-9º 55´n, 79º 30´e-81º 55´e, by lower to middle pleistocene (1.806-0.781 ma). during this drifting period from lower to middle jurassic, sri lanka was subjected to at least four major upliftments through jurassic, miocene, pliocene and pleistocene times (wayland 1919, deraniyagala 1958, cooray1984). as an ‘upliftment’ in geological terms, is a consequence of tectonic activity, this author is of the view that such major upliftments did not occur for the formation of “the face of sri lanka” during this geologic period, and proposes a new “planation surface concept” together with minor tectonic activity to reconstruct the morphogenesis of sri lanka’s topography based on glacial events during drifting of sri lanka from the southern hemisphere to the northern hemisphere. accordingly, it is possible to identify “four major planated surfaces” developed in response to climatic and sea level fluctuations, which followed the glaciations and de-glaciations. such events broke up the existing glaciofluvialsedimentary beds transforming the topography and structure of sri lanka. at present, the “first planated surface” is now submerged (figure 1), which has been identified as a ‘submerged plateau’ by sommerville (1907) and submerged peneplain by ’deraniyagala (1958). sedimentary rocks of the upper jurassic age in north-west sri lanka are preserved in at least three faulted basins within the crystalline vijayan complex (table 1). for example, tabbowa beds (generally arkoses) and andigama-pallama beds arkoses and carbonaceous shales with thin coal slivers) were formed locally onshore within fault-bounded basins (cooray 1984). one of these basins, that on the west of tabbowa tank, 12.8 km from puttalam on the road to anuradhapura, is exposed at the surface. the shales, which are at andigama and pallama, about 21 and 43 km respectively due south of tabbowa, are completely covered by later deposits. similar deposits lie almost in a straight line with similar faulted basins near chennai on the east coast of peninsular india, nearly 320 km to the north, and it is probable that all these jurassic sediments were deposited at the same time (cooray 1984). the sediments were laid down on the margins of gondwanaland which included parts of what are now known as india, australia, antarctica, south america, africa and madagascar. by the upper jurassic period sri lanka was detached from the southern supercontinent gondwanaland, and the indian ocean began to open up. the landmasses of india and sri lanka separated from australia and the antarctica/australia plate.as the climate warmed up the glacial meltwater deposited the coarser material near the terminal end of the glacierand the finer material further away. such phenomena are salient features of paleoclimate of sri lanka. the lower cretaceous (145.5-113.0 ma) was a mild "ice house" world (ics, 2009). there was snow and ice during the winter seasons, and cool temperate forests covered the polar regions. during the upper cretaceous the global climate was warmer than today's climate. no ice existed at the poles. dinosaurs migrated between the warm temperate and cool temperate zones as the seasons changed. “post-gondwana” highland landscapes in sri lanka emerged (king 1962). at some stage during the cretaceous period (145.0-72.1ma) more than 850m thick sandstones were deposited in the mannar basin. between 145.0 ma and 113.0 ma, in lower cretaceous, sri lanka rotated anticlockwise from ene-wsw to ne-sw while translocating northwards from 58 o s-60 o s to 13 o e-16 o e. by upper cretaceous sri lanka moved further north and east to a position within 54 o s-57 o s, 30 o e-35 o e. due to these changes,namely, anticlockwise rotation and northward movement sri lanka’s “second planated surface” (present surface including the coastal plain) was formed by extensive retreating glaciers again (figure 1).similarly, the “third planatedsurface” and the “fourth rugged central highland” of sri lanka emerged due to thawing of massive glaciers (figure 1), which covered central highland and third planation surface since palaeocene to oligocene periods. within these periods, sri lanka moved from 31 o s-34 o s and 55 o e-58 o e to 9 o s-13 o s and 66 o e-69 o e passing the tropic of capricorn. katupotha /journal of tropical forestry and environment vol. 3, no. 01 (2013) 45-57 49 figure 1: diagrammatic section across sri lanka from west to east showing the four planated surfaces. i first (submerged), ii– second (flat terrain to undulating terrain, rolling and hilly terrains, iii third (dissected rolling and hilly; steeply dissected rolling and hilly terrains, and lv fourth (mountainous and rugged central highland) with the emergence of planated surfaces and central highland of sri lanka as third and fourth planated surfaces, important depositional features of glaciofluvial origin including outwash plain, valley terrains, erratic boulders, ice-rafted deposits (eskers and tills), kames and kame terraces and streams fed deposits were formed. the climate during the miocene was similar to today's climate, but warmer. welldefined climatic belts stretched from pole to equator and continents continued to drift toward their present positions. king (1962) postulated that the extreme planation of plateau in sri lanka, survived only on smooth ridges or crests. this would be the “third planated surface” in the country. antarctica continued to become more isolated and finally developed a permanent ice cap (ics 2009). by the end of the oligocene period sri lanka reached 2 o e-7 o s and 73 o e-76 o e and passed the equator by mid miocene (15.97-13.82 ma) with the position around 0.3 o n-4.30 o n and 73 o e-76 o e (table 1). as a result of the pliocene-quaternary climate changes the earlier glacial sedimentary deposits in sri lanka disappeared from the greater part of sri lanka and at present such deposits can be identified as patches from several parts of the country.there are no pleistocene glacial deposits have been reported, because by the quaternary period, sri lanka had already reached its present position. however, scattered erratic boulders and patches of old ice-rafted deposits from former glacial depositions such as, outwash plains, valley terrains, kames and kame terraces can be identified throughout on first, second and third planated surfaces, although most are worn to shadows. as a glacial deposit, an erratic is a piece of rock that differs from the size and type of rock native to the area in which it rests. erratics can range in size from pebbles to large boulders such as big rocks (hundreds to thousands of metric tons in weight). geologists identify erratics by studying the compositions and orientation of surrounding rocks in comparison to the composition and orientation of the erratic itself.clast petrology(grains of sediment, silt, sand, gravel, etc), provenance and shape data for the middle pleistocene glaciofluvial sand and gravel of the mníšek member have been discussed by nývlt and hoare (2011).the results are compared with those for in situ weathered bedrock debris and recent fluvial sediments from the same area. the results of this study would be helpful to investigate glaciofluvial sediments in sri lanka. due to the pliocene-quaternary climate changes, the earlier glacial sedimentary deposits in sri lanka have disappeared from greater part of sri lanka. however, there are no pleistocene glacial deposits in sri lanka, but scattered erratic boulders and patches of ice-rafted deposits can be identified as glacial deposits older than pleistocene glaciation. likewise, outwash plain type landforms can be identified from the “second and third planated surfaces”, while valley terrains can be identified from the upper part of the “third planated surface” and from the “rugged central highland” area. erratics are significant because since they are transported by glaciers, they are one of a series of indicators which mark the path of glacier movement. their lithographic origin can be traced to the parentrock, allowing for confirmation of the ice-sheets flow route. similarly they can be transported by katupotha /journal of tropical forestry and environment vol. 3, no. 01 (2013) 42-54 50 ice-rafting. ice-rafted debris or ice-rafted deposits and stream feddeposits were deposited onto the bottom of the water body, for example, onto a river bed or an ocean floor. erratic boulders at tennamavadi are located at coordinates 8°58"n and 80°58'e in sri lanka’s northeastern coastal zone very close to the present coast. the locality is about15-20m above msl and 1.5 km southwest of kokkilai lagoon mouth, (figure 1). colour and mineral composition indicate that the rocks are derived from the highland complex rocks. they are mainly quartzite, marbles, garnet-sillimanite-schist and chanockitic gneisses. the erratic boulders at valaichchenai lagoon (coordinates 7°56'n, 81°33'e), and uraniya (pottuvil) lagoon (coordinates 6°53'n, 81°50'e) are about 2.0m 4.0m above msl (figure2). the lithology of these boulders being composed of a heterogeneous group of gneisses, migmatites and granites with scattered sedimentary bands confirm the source to be highland complex rocks (cooray 1984). the erratics exhibit rounded, oval and elongated shapes ranging in from pebbles to large boulders hundreds to thousands of metric tons in weight. these appear to have been dropped on rock outcrops or on the ground by melting glaciers moving in a northeasterly direction. erratic boulders at kadigawa (coordinates 7°42'n and 80°00'e) and kadigawa temple area (coordinates 7°43'n and 80°00’e) in the kurunegala districtnorthwestern province are located on the second planated surface. the area is 35 40m above the present msl. erratic boulders at nakolagane temple site (coordinates 7°48'n and 80°18'e, photograph 4) and erratic boulders at viharagala temple site (coordinates 7°46'n and 80°28'e, figure3) in the kurunegala district, northwestern province are located above 120 to 200m msl. the boulders of the northwestern province are derived from the rocks of highland and wanni complexes. the wanni complex is composed mainly of quartzites, calc-silicate gneisses, cordierite gneisses, garnet-sillimanite gneisses, garnet-biotite gneisses, quartzofeldspathic gneisses, metagranites (including pink granites), granitoid gneisses, charnockites, meta-diorite, amphibolites, meta-gabbros, migmatites, monzo-diorite and pegmatites. premarathne and jayasena (2009) report that the hillocks named weudakanda and erapolakanda in the kurunegaladistrict are covered with residual and colluvial soils. some of these soils are reddish brown in color. sub-aerial tropical weathering may have converted the original transported materials to iron-rich brown and reddish brown earth. an alternate statement proposed is “descending from weuda towards the western coast in the northwest plain, several intriguing isolated deposits were encountered immediately hinterland of the coastal area.” they are the white sand deposits of nattandiya and its nearby figure 1: showing erratic boulders at tennamavadi (coordinates 8°58'n, 80°58'e), about 1.5 km southwest of kokkilai lagoon mouth, 15 -20m above msl in northeast coast. figure 2: showing erratic boulders at uraniya (pottuvil) lagoon (coordinates 6°54n, 81°50'e), 3m above msl, east coast. katupotha /journal of tropical forestry and environment vol. 3, no. 01 (2013) 45-57 51 areas and ferruginized, indurated gravel bearing deposits exposed at erunwela, muttibendivila, pallama, metiyagane and (in the subsurface of hummocks throughout the lower plains in the northwest (wayland 1919, coates 1935, deraniyagala 1958, cooray 1963 and 1984). the original transported materials were converted to iron-rich brown and reddish brown earth embedded with well rounded quartz gravel to pebble size are found in a hummocky area at leekolawewa in the kurunegala district (photograph 5). the sizes of the well rounded and oval shaped pebbles and cobbles vary from 2.0 cm to 8.0-10 cm. this author believes that these sediments represent weather-worn outwash plain deposits produced at several stages during the glacial history. between kaduwela and hanwella on the kelani ganga (western province), for example, a highlevel gravel known as the “malwana formation” is present at 16m above the present river level (28m above msl); a lower gravel, the ranale formation, is found at 6.5m above the present river level (23m above msl; photograph 6). the malwana formation contains beds of well rounded, coarse quartz pebbles embedded in a matrix of laterite separated from each other by pebble-free layers of laterite. remnants of this formation are seen capping the ridge that runs parallel with the river in ranale and nawagamuwa villages on the left bank of the kelani ganga (river), and at mapitigama, weelgama, thittapattara, and wiyalananda villages on the right bank of the same river (cooray 1984). the ranale gravel forms a terrace about a 1-2 km wide and at a height between 10-25m above msl. it is about 3-4m thick probably formed as ice-rafted palaeo deposits during the progressive lowering of the river valley at a later stage. outcrops of these gravels can be seen at several scattered locations along the valley on either side of the kelani river, some of them being away from its present course. well rounded and polished quartz pebbles, about 2.0 cm to 8.0 cm in size, embedded in a matrix of laterite separated from each other by a pebble-free layer of laterite is shown. these erratic boulders and ice-rafted deposits can be correlated with the pattern of sedimentation during the late paleozoic, gondwanaland glacial sediment from the talchir formation, satpura gondwana basin, central india (chakraborty and ghosh, 2008). figure 3: erratic boulders at viharagala temple site (coordinates 7°46'n, 80°28'e). figure 4: erratic boulders at nakolagane temple site (coordinates 7°49’n, 80°19’e) both in kurunegala district. katupotha /journal of tropical forestry and environment vol. 3, no. 01 (2013) 42-54 52 4. conclusion climate changes and variations in sea level, which followed the glacial cycles from huronian glaciation to karoo glaciation in the southern hemisphere continued during the northward drift of the landmass. due to such changes, much of the southern hemisphere remained covered by ice as glaciers pushed northward during the lower permian time (299.0-279.3 ma. by lower triassic (252.0-251.2) ma, the interior of pangea was hot and dry and warm temperate climates extended to the poles. in due course, the interior of pangaea became less dry, and seasonal snow and ice frosted the polar regions. sri lanka emerged as a separate landmass between201.3 and 166.1 ma (lower and middle jurassic), when the landmass was positioned within 52 o s-55 o s and 17 o e-22 o e. sri lanka reached its present positionwithin 5º 52´n-9º 54´n and 79º 30´e-81º 55´e at sometime between lower and middle pleistocene although many workers proposed that sri lanka was subjected to at least four major upliftments during jurassic, miocene, pliocene and pleistocene times, this author is of the opinion that such major upliftmentsdid not occur during the said geologic periods, and instead introduces the new “four major planation surface concept” to interpret the morphogenesis of sri lanka leading to its present topography based on major glacial events during drifting of sri lanka from the southern to the northern hemisphere. the concept of “four major planation surfaces” states that pervasive climatic changes and significant sea level fluctuations that occurred since jurassic, miocene, pliocene and pleistocene times led to the brake up of glaciofluvialsedimentary beds altering the country’s topography and structural configuration. the pliocene-quaternary climates changes appear to have obliterated earlier glacial sedimentary deposits from greater part of sri lanka. despite no pleistocene glacial deposits have been recorded, scattered erratic boulders without proper direction and patches of relict erratic pebbles or stream fed deposits can be identified near the coastal zone (second planated surface). in addition, the second and third planated surfaces as well as the rugged central highlands of sri lanka (fourth planated surface), together with glacial deposits that are older than those of pleistocene glaciation provide conclusive evidence for sri lanka had endured palaeoclimatic changes and glaciations. figure 5: a gravel hummock at leekolawewa (coordinates 7°42'n, 80°02'e), about 40m above msl, in northwestern province. figure 6: ranale gravel deposit (coordinates 6°55'n, 80° 02'e), 22m above msl in western province (as streams fed deposits) katupotha /journal of tropical forestry and environment vol. 3, no. 01 (2013) 45-57 53 acknowledgments my profound thanks go to mr nimal ranasinghe, former director, geological survey department of sri lanka and dr. risto hamari, pahnakalliontie 4 c 14, 48400 kotka, finland for their pertinent suggestions and editing of the manuscript. i am deeply grateful to professor gamini adikari, director general, central cultural fund of sri lanka and international water management institute (iwmi) for providing ready assistance for all field visits, and also this study has been completed based on the research and development allowance paid by university (management services circular no: 44 and the letter of ugc/c/ps/7 dated 14 march, 2011). references chakrabortychandan and ghoshsanjoy kumar., 2008. pattern of sedimentation during the late paleozoic, gondwanaland glaciation: an example from the talchir formation, satpura gondwana basin, central india. journal of earth system science, vol. 117, no. 4, august 2008, pp. 499-519. cooray, p.g., 1963. the erunwela gravel and the probable significance of its ferricrete cap. ceylon geographer, 17: 39-48. cooray, p.g., 1984. an introduction to the geology of sri lanka (2nd edition), national museum of sri lanka publication, colombo, 340 p. cooray, p.g., 1994. the precambrian of sri lanka: a historical review (abstract). precambrian research 66, (1-4), february 1994, pages 3-18 caputo, m.v. and crowell, j.c. 1985. migration of glacial centers across gondwana during paleozoic era (abstract). geological society america, bulletin 96:1020-1036. dahanayake, k., and dassanayake, d.m.s.m., 1981. glacial sediments from weuda sri lanka, sedimentary geology 30, 1-14. deraniyagala, p.e.p., 1958.the pleistocene of ceylon, ceylon. national museum publication, colombo. 1956; pp: 1-16. dubiel f. russell, parrish judith totman, parrish j. michael and good c. steven., 1991. the pangaeanmegamonsoon.evidence from theupper triassic chinle formation, colorado.pp 347-370. felix m. g., james g. o., alan g. s., wouter, b., lucas j. l., 2004.a new geologic time scale, with special reference to precambrian and neogene. episodes, 27, 2.pp 83-100. hölzl, s., köhler, h., kröner, a., and liew, t.c., 1991.geochronology of the sri lankan basement. in: kröner, a. (ed.), the crystalline crust of sri lanka, part 1: summary of research of the german-sri lanka consortium, geological survey department of sri lanka, professional paper 8. 1991: pp. 237257. horton e daniel, christopher j. poulsen, montañez p. isabel and william a. dimichele., 2012.eccentricity-paced late paleozoic climate change.palaeogeography, palaeoclimatology, palaeoecology 331–332 (2012) 150–161. ics., 2009. international stratigraphic chart, retrieved 2009-09-25. international commission on stratigraphy, available at: http://www.stratigraphy.org/chus.pdf. jinnan tong and parrish j.t., 1999. the pandean megamonsoon and climate change in south china during the triassic. proceedings of the international conference on pangea and the paleozoicmesozoic transition, march 9-11,1999. katupotha, j., 1988a. evolution of the coastal landforms in the western part of sri lanka. geographical sciences (hiroshima univ.), v 43 (1), 18-37. katupotha, j., 1988b. hiroshima university radiocarbon dates 1, west and south coasts of sri lanka. radiocarbon, 30(1): 125-128. katupotha, j., 1988c. hiroshima university radiocarbon dates 2, west and south coasts of srilanka. radiocarbon, 30(3): 341-346. katupotha /journal of tropical forestry and environment vol. 3, no. 01 (2013) 42-54 54 katupotha, j. 1995: evolution and geological significance of holocene emerged shell beds on the southern coastal zone of sri lanka. journal of coastal research, 11 (4), 1042-1061. katupotha, j. and dias, p., 2001. the geological evolution correlated to the stratigraphy of thekalpitiya peninsula. journal of indian association of sedimentalogists. 20(1), 21-37. king, l. c., 1962.the morphology of the earth.oliver and boyd, edinburgh and london.pp 324-326. kröner, a., cooray, p.g., and vitanage, p.w., 1991.lithotectonic subdivision of the precambrian basement in sri lanka. in: kröner, a. (ed.). the crystalline crust of sri lanka. part 1: summary of research of the german-sri lanka consortium, geological survey department of sri lanka, professional paper 8. 1991; pp. 5-21. nývlt, d. & hoare, p. g., 2011: petrology, provenance and shape of clasts in the glaciofluvial sediments of the mníšek member, northern bohemia, czechia. sbor.geol. věd, antropozoikum, 27, 5–22. poulsen j christopher, isabel pollard david, montañez, p and rowley david., 1977.late paleozoic tropical climate response to gondwanandeglaciation.geology, 35(9), 771-774. premarathne d.m.u.a.k. and jayasena h.a.h., 2009.paleozoic glacial sediments of sri lanka obliterated by neotectonicevents?weuda deposits revisited. journal of geological society of sri lanka vol. 13 (2009), 105-111. quesnel, f., barbarand, j., sevin, b., ricordel-prognon, c., cluzel, d., maurizot, p., gautheron, c., 2012. can we use the planation surface concept to reconstruct the morphogenesis of new caledonia, first low temperature thermochronologicaldata. 34th international geological congress, brisbane: australia. steiner b maureen and wallick p brian., 1992. jurassic to paleocenepaleolatitudes of the pacific plate derived from the paleomagnetism of the sedimentary sequences at sites 800, 801, and 802 (23). in larson, r. l., lancelot, y., et al., 1992. proceedings of the ocean drilling program, scientific results, vol. 129, 431-446. sommerville, b. t., 1907. the submerged plateau surrounding ceylon, spoliazeylanica 5 (18), 69-79. vitanage p.w., 1972. post precambrian uplift and regional neotectonic movements in ceylon, proc 24th igc, section 3, montreal, 642-653. wanless, r. harold and cannon r. julie., 1966. late paleozoic glaciations. earth-science reviewsvolume 1, issue 4, may 1966, pages 247-286 wayland, e.j., 1919. outline of the stone age of ceylon. spoliazeylanica, 11, 85-125. wickramathilake et al., /journal of tropical forestry and environment vol. 3, no. 02 (2013) 66-75 66 impacts of woody invader dillenia suffruticosa (griff.) martelli on physiochemical properties of soil and, below and above ground flora b.a.k. wickramathilake 1* , t.k. weerasinghe 2 and s.m.w. ranwala 3 1 department of zoology, open university of sri lanka, nawala, nugegoda 2 department of botany, the open university of sri lanka, nawala, nugegoda 3 department of plant sciences, university of colombo, colombo 03 date received: 20-04-2013 date accepted: 29-10-2013 abstract dillenia suffruticosa (griffith) martelli, that spreads fast in low-lying areas in wet zone of sri lanka is currently listed as a nationally important invasive alien species that deserves attention in ecological studies. thus, impact of this woody invader on physical, chemical properties of soil and below and above ground flora was investigated. five sampling sites were identified along a distance of 46km from avissawella to ratnapura. at each site, two adjacent plots [1m x10m each for d. suffruticosa present (d +) and absent (d )] were outlined. physical and chemical soil parameters, microbial biomass and number of bacterial colonies in soil were determined using standard procedures and compared between d + and d by anova using spss. rate of decomposition of d. suffruticosa leaves was also determined using the litter bag technique at 35% and 50% moisture levels. above ground plant species richness in sample stands was compared using jaccard and sorenson diversity indices. decomposition of d. suffruticosa leaves was slow, but occurred at a more or less similar rate irrespective of moisture content of soil. particle size distribution in d + soil showed a much higher percentage of large soil particles. higher % porosity in d + sites was a clear indication that the soil was aerated. the ph was significantly lower for d + than d thus developing acidic soils whereas conductivity has been significantly high making soil further stressed. the significant drop in cation exchange capacity (cec) in d + soil was a remarkable finding to be concerned with as it correlated with fertility of soil. significantly higher values of phosphates reported in d + soil support the idea that plant invaders are capable to increase phosphates in soil. higher biomass values recorded for d + sites together with higher number of bacterial colonies could be related to the unexpectedly recorded higher organic carbon. both the jaccard and sorenson indices indicated that d + and d sites were dissimilar with respect to above ground plant species richness. thus, changes in above ground vegetation and soil properties due to the invasion were identified and further studies are needed for determining the degree of soil deterioration due to the invasive behavior of d. suffruticosa. key words: dillenia suffruticosa, soil properties, sri lanka, invasive species, microbial biomass 1. introduction invasive alien species (ias) cause tangible ecological and economic damages by altering goods and services provided by the environment (charles and dukes, 2007, parker, 1999, primental et al., 2000). one major reason for these irreparable and irreversible impacts of ias has been related to their ability to modify * correspondence: amilawickramathilake@gmail.com tel: +94 71 5497539 issn 2235-9370 print / issn 2235-9362 online ©2013 university of sri jayewardenepura wickramathilake et al., /journal of tropical forestry and environment vol. 3, no. 02 (2013) 66-75 67 physical resources of the environment in ways that differ from resident plant associations (ehrenfeld, 2004, weidenhamer and callaway, 2010). many invasive plant species have high specific leaf areas, faster growth rates and increased leaf nutrient concentrations relative to the resident species of the same sites, and these traits change soil properties via modifying rates of decomposition and nutrient cycling in the soil environment (allison and vitousek, 2004). additionally, allelopathic, defensive, or antimicrobial chemicals of plant invaders act as novel weapons and play a vital role in uniquely affecting the biogeochemistry of the soil to maintain the dominance of plant invaders (callaway and ridenour, 2004, laio et al., 2008). there is much evidence that invasive plant species can modify physical or chemical attributes of soil, including inputs and cycling of nitrogen and other elements (laio et al., 2008, nicholas et al., 2008, parker et. al., 1999, walker and smith, 1997). for many years knowledge on impacts of ias in sri lanka was mostly based on anecdotal observations, but in recent years empirical evidences on many aspects of ias have been multiplied. although studies on the impacts of plantation crops and many agricultural crops on sri lankan soils have been studied (weerasinghe, 2012, weerasinghe and weerasinghe, 2007), impacts of many ias, both on soil and native species remain understudied (jayaratne and ranwala, 2010). para, (dillenia suffruticosa (griffith) martelli., family dilleniaceae) is one such example. dillenia suffruticosa, native to east asia, was introduced to sri lanka as an ornamental plant to royal botanical gardens in 1882 from boneo. it is a light demanding woody shrub that could grow up to 6m tall in open lands in moist soil, thus proliferated fast as dense stands in the wet-low country of sri lanka inhabiting many marshy/semimarshy areas (including abandoned paddy fields) in kalutara, galle and ratnapura districts, posing a threat to native biota. shade provided by its large leaves hinder undergrowth and accumulation of litter created a favourable habitat for mosquitoes, thus raising human health issues in the surroundings. when growing in riparian habitats it influenced sedimentation rates (ranwala, 2011). these impacts listed d. suffruticosa as a nationally important ias over the last ten years (wijesundara, 1999, 2010). it was also recognized as an alternate host for oil palm nettle caterpillar setoranitens in malaysia (lim et al., 2001). however, important uses of d. suffruticosa have also been documented. ability to staunch bleeding (ahmed and holdsworth, 1995), anti-fungal (johnny et al., 2011, wiart et al., 2004) and phytoremediation (rahim et. al., 2011 ) properties, usage of live poles as an effective and economical means of slope stabilization in bio-engineering (abdullah et al., 2012, prasad et al., 2012, sasan et al., 2009) are among them. control through utilization has been suggested as an ecofriendly approach in ias management (geesing et.al.,2004) but at the same time, concern on ias as ecosystem engineers (crooks, 2002, walker and smith, 1997) cannot be neglected. as ias alter structure and function of invaded ecosystems by modifying physical, chemical and biological resources, impact analysis is considered very important. despite the widespread global attention on ias, studies on their qualitative and quantitative consequences on the environment have not been well documented in many countries (callaway and maron, 2006, jayaratne and ranwala, 2010, richardson and van-wilgen, 2004). in this context, we describe some impacts of d. suffruticosa on its immediate neighborhood through this paper. the present work examined changes in physical, chemical properties of soil and below and above ground flora between stands with and without d. suffruticosa. hence the study was conducted with the following objectives. firstly, to determine the decomposition time and rate of leaves of d. suffruticosa. secondly to identify the effects of d. suffruticosa on physical parameters of soil such as particles-size distribution, bulk density, porosity percentage and chemical parameters such as ph, conductivity, cation exchange capacity and nutrients (mainly nitrates and phosphates) in soil. thirdly, to recognize the effect of d. suffruticosa on below ground flora (microbial biomass and bacterial colonies of soil) and above ground vegetation in invaded sites. wickramathilake et al., /journal of tropical forestry and environment vol. 3, no. 02 (2013) 66-75 68 2. materials and methods 2.1 study sites sampling sites, s1-s5 were selected at a total distance of 46 km along the high level road between awissawella and ratnaputa based on visual observation of presence of d. suffruticosa. at each site, two 1m x10m size adjacent plots were randomly outlined to represent presence (d + ) and absence (d ) of d. suffruticosa. the regional climate of the study sites was wet, humid and warm with an annual average rainfall > 2500mm, overall year round temperature approximately at 30 o c. the stands contained red yellow podsolic soils. 2.2 determination of time and rate of decomposition of d. suffruticosa leaves fifty nylon mesh bags (8cm ×10cm, pore size 0.25mm 2 ) each containing 2g of leaf matter were prepared using air dried mature leaves of d. suffruticosa. bags were sealed and kept buried (3 per pot) approximately 5cm beneath in 16 pots containing soil obtained from natural habitat of d. suffruticosa. two bags were kept out of water at room temperature (30 o c). to simulate natural moisture contents of soil, two equal sets of pots were maintained at 35% and 50% moisture levels under greenhouse conditions (30 o c). at 14 day intervals, 3 litter bags were removed from each set of pots and separately washed several times followed by air drying for seven days. residues were carefully taken out, oven dried at 70 0 c until a constant weight was obtained. the mean mass loss of residues was calculated and plotted against decomposition time. time taken for 50% loss of the initial mass (t50) was obtained for each moisture level. decomposition rate was calculated by log n (wt/w0) = log nw0-kt50 ,where wt= weight of residue remaining at time t50, w0 = initial weight of residues, t50 = time taken for 50% loss of the initial mass, k = decomposition rate, according to anderson and ingram (1993). 2.3 determination of physical and chemical properties of soil a composite soil sample was obtained from each of the plots twice a year (6 month intervals). physical parameters of soil such as particles-size distribution, water retention capacity, bulk density, porosity % and chemical parameters such as ph, conductivity, cation exchange capacity and nutrient levels (mainly nitrates and phosphates) were tested in d + and d according to hess, (1971). data analyses for each parameter were done by two way analysis of variance using spss software (version 16) to assess the significant (p= 0.05) impacts occurred due to the presence of d. suffruticosa during sampling times. 2.4 determination of the changes in below and above ground flora due to the presence of d. suffruticosa. soil samples obtained for above physical and chemical analyses were also used to compare below ground flora such as microbial biomass and number of different bacterial colonies between d + and d soil. microbial biomass was measured using fumigation incubation technique as per jenkinson and powlson (1976) while number of bacterial colonies was enumerated according to robert et. al., (1957). to identify the effect on above ground flora, height and crown cover percentage of d. suffruticosa and number of undergrowth plant species was recorded in d + and d plots at each site. similarity of above ground vegetation between d + and d plots was compared for each site by jaccard [isj = c/( a+ b+ c)*100] and sorenson [iss = c /½( a+ b)*100] similarity coefficients (muleller dombois and ellenburg, 1974) where a and b were species richness in d+ and dplots respectively and c = number of species common to both d + and d . 3. results 3.1 time and rate of decomposition of d. suffruticosa leaves dillenia suffruticosa leaves decomposed at a rate of 0.014g/day and 0.011g/day respectively at 35% and 50% moisture levels taking 98 and 126 days for a 50% weight loss (figure 1). wickramathilake et al., /journal of tropical forestry and environment vol. 3, no. 02 (2013) 66-75 69 figure 1: remaining weight of dried d. suffruticosa leaves during decomposition at 35% and 50% moisture levels 3.2 change in physical and chemical properties of soil our results indicated that d. suffruticosa tend to increase the percentage of large particles in soil (figure 2a) simultaneously and significantly increasing the porosity of soil (figure 2b). however, bulk density and water retention capacity did not vary significantly between d+ and dsoil. it was also found that there was no influence of the time of data collection on soil parameters investigated above. (a) (b) figure 2: change of a) particle size distribution >1mm, and, b) percentage porosity in d + and d soils. the ph of the soil was significantly reduced (6.00 vs 6.40, p=0.05) and conductivity of soil was significantly increased (25.64 vs 18.24, p=0.05) by the presence of d. suffruticosa. further, the cation exchange capacity was significantly affected (figure 3a) while an increase in % organic carbon in d + plots also observed (figure 3b). invasion of d. suffruticosa significantly increased the phosphate content of soil. there was no significant change in the nitrate content due to the presence of the woody invader (figure 4). 0 0.5 1 1.5 2 2.5 0 20 40 60 80 100 120 140 160 r e m a in in g w e ig h t ( g ) decomposition time (days) 35%moisture level 50%moisture level 0 10 20 30 40 50 60 70 1 1.7 3.35 % p a rt ic le s particle size (mm) d+ d0 5 10 15 20 25 30 35 40 d+ d% p o ro si ty presence (d+)/ absence (d-) of d. suffruticosa wickramathilake et al., /journal of tropical forestry and environment vol. 3, no. 02 (2013) 66-75 70 (a) (b) figure 3: change in a) cation exchange capacity b) percentage organic carbon in soil between d. suffruticosa present and absent stands figure 4: change in nitrate and phosphate contents in soil by d. suffruticosa 3.3 changes in below and above ground flora due to presence of d. suffruticosa the microbial biomass (figure 5) and the number of bacterial colonies reported from soil was relatively high in d + plots (166 x10 5 vs 97x 10 5 g 1soil, p=0.05) indicating that the invader promoted the existence of diverse micro flora in soil. observations revealed that presence of d. suffruticosa had significantly changed the composition and richness of undergrowth plant species under its stands. further, it was noticed that species richness of undergrowth vegetation was inversely related to crown cover of d. suffruticosa which was about 2-3m tall in fully grown shrubs. at 100% crown cover no undergrowth was found. both the jaccard and sorenson indices confirmed that d + and d sites were dissimilar with regard to plant species richness (table 1). 0 5 10 15 20 25 30 35 40 45 d+ dc a ti o n e x c h a n g e c a p a si ty ( n t u ) presence (d+)/ absence (d-) of d. suffruticosa 0 0.5 1 1.5 2 2.5 3 3.5 d+ do rg a n ic c a rb o n % presence (d+)/ absence (d-) of d. suffruticosa 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 nitrate phosphate c o n c e n tr a ti o n ( µ g /m l) type of nutrient d+ dwickramathilake et al., /journal of tropical forestry and environment vol. 3, no. 02 (2013) 66-75 71 figure 5: change in microbial biomass in soil between d. suffruticosa present and absent stands table 1 .similarity coefficients obtained for d + and d plots at five sampling sites. isj= jaccard similarity coefficient and iss= sorenson similarity coefficient sampling site gps coordinates cover of d. suffruticosa in d + isj iss (s1) getaheththa lat 6;54;39.866, lon 80;13;29.8219 100% 4.76 4.76 (s2) eheliyagoda lat 6;50;294059 lon 80;16;18.5459 50% 5.26 5.55 (s3) parakaduwa lat 6;49;28.272 lon 80;18;16.776 50% 0.00 0.00 (s4) kuruwita lat 6;47;30.221 lon 80;20;33.532 100% 0.00 0.00 (s5) ratnapura lat 6;42;50.062 lon 80;22;50.432 100% 0.00 0.00 4. discussion invasive alien plant species impose multitude of impacts on structure and function of the ecosystem through direct or indirect effects on abiotic and biotic components of the environment (charles and dukes, 2007, parker et. al., 1999, walker and smith, 1997) and our results are also in favor of this idea to a certain extend. plant invaders, mainly through their litter and root exudates change soil structure and nutrient cycles, mobilize and/or chelate nutrients, modify soil nutrient pools and diversity of soil biota. these effects on soil biogeochemistry are not only closely linked to the nutrient stoichiometry and secondary metabolites of leaf tissues but also the rate of decomposition of plant litter which play a pivotal role in releasing nutrients and chemicals into soil (ehrenfeld, 2003, 2004, weidenhamer and callaway, 2010). single species litter dynamics have shown that rate of litter decomposition and nutrient cycling are closely correlated with site environmental conditions (particularly climate), litter chemistry, composition of soil biota and the moisture content of soil (swift et.al., 1979). as proven by our results, ability of d. suffruticosa to decompose its litter in a more or less same rate at high and low moisture levels (under the same environmental conditions) could be attributed to its broad tolerance limits (allison and vitousek, 2004) to withstand commonly prevailing moisture fluctuations of the soil. in such instances the invader is said to pose a threat to native species by 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 d+ dm ic ro b ia l b io m a ss ( µ m o l/ 1 0 0 g s o il presence (d+) /absence (d-) d.suffruticosa wickramathilake et al., /journal of tropical forestry and environment vol. 3, no. 02 (2013) 66-75 72 delaying decomposition of their litter as many native species require substantial amount of water to efficiently decompose leaf litter in wet and warm environments (facelli and picket, 1999). presence of a large proportion of easily decomposable substances in plant tissues is reflected by higher decomposition rates of litter and this characteristic serves as a trait of invasiveness. however, according to our results d. suffruticosa exhibited a slow decomposition rate (average of 12.5mg/day and (t50) 105 days) compared to lantana camara (rate 126 mg/day and t5011 days) and croton lacciferus (average rate 154 mg/day and t5009 days) under more or less similar climatic and soil conditions (ranwala, unpublished data). although litter quality was not investigated in this work, according to hirobi et al., (2004), low nutrients (n= 8.7, p= 0.19, k= 1.83, ca= 7.09, mg=2.16 mg g -1 ) and high amount of acid insoluble residue (368.2 mg g -1 ) in d. suffruticosa leaves were responsible for slow decomposition rates. our results proved that the presence of d. suffruticosa structurally alter soil by creating larger soil particles and many air pores, thus making the soil much aerated. acidity and high conductivity of soil under d. suffruticosa stands further indicated that the soil chemistry was affected probably be due to the accumulation of more h+ ions, minerals released from litter, inputs of co2 into substrate and or release of secondary metabolites/exudates by the invader (kelly et. al., 1998). however, further work is required to comment on the mechanism. as proven by our results, cation exchange capacity (cec), which plays a major role in deciding the fertility status of soil, was also affected by the presence of d. suffruticosa. significantly decreased cec of soil in d. suffruticosa stands was a major evidence to show that mobility of nutrients has been affected by the invasive plant. reduced cec in the present study is an important finding to be concerned with as this could directly interfere with the absorbance and exchange of nutrients of any native species in the neighborhood. increased organic carbon content exhibited by the plots with d. suffruticosa in our results served as an indication of the species potential of increasing soil organic carbon stock and hence soil fertility in invaded sites. however, addition of carbon stimulates soil microbial growth, which in turn accumulates soil nitrogen in their biomass limiting the availability of nitrogen to plants in many instances (vitousek, 1982). the study was not able to identify any difference in nitrate content between d + and d soils but in available phosphates. this finding correlates with martin et. al., (2009) which states that higher content of soil phosphates was common in many terrestrial invasions. however, further research is needed to ascertain whether this elevated phosphorus was brought through the invasive plant (weidenhamer and callaway, 2010) or activated by soil microbial biomass. this increase could also be attributed to the increased acidity which may assist to convert non soluble phosphate to soluble phosphates in the soil environment (hedley et. al., 1983). movement of nutrients in soil is biologically mediated, thus changes in soil microbiota could be linked to changes in nutrient cycling of soil (katherine et.al., 2006). at the same time, the abundance, composition and activity of the decomposing community is directly influenced by the plant and its litter resource (couteaux et al., 1995, el-shatnawi and mukhadmeh, 2001, kourtev et al., 2002). higher microbial biomass observed in d + soils in this study may have also contributed to alter soil chemical properties under d. suffruticosa stands, but, further investigations on microbial composition are required to comment on this change. as soil is degraded with the increase of unfavorable microorganisms in soil (katherine et.al., 2006), it would be worthy to investigate on the changes in populations of favourable or unfavourable microorganisms between d + and d soil. in general diversity, density of plants is expected to be high in places where ample sunlight is supplied (bazzaz and picket, 1980). it was clearly understood that d. suffruticosa suppress undergrowth plant species richness/composition by physically shading the floor and probably suppressing establishment and growth of seedlings of the resident species. many ias alter species assemblages in communities; reduce abundance and richness of the neighborhood by increasing above and below ground competition for resources such as light and nutrients and by exuding secondary metabolites through roots and plant litter (meier and bowman, 2008, vilà and weiner, 2004, yurkonis et. al., 2005, xiong and nilsson, 1999). these wickramathilake et al., /journal of tropical forestry and environment vol. 3, no. 02 (2013) 66-75 73 prevent seedling establishment, inhibit growth and development of resident plant species thereby creating feedbacks for continued invasion in many ecosystems. our work also confirmed that the woody invader, d. suffruticosa modify its neighborhood by altering soil properties and above ground community composition. references abduliah, m.n., osman, n., ali, f.h., 2011. soil-root shear strength properties of some slope plants. sains malaysiana, 40, 1065–1073. ahmad, f. b., holdsworth, d. k. 1995. traditional medicinal plants of sabah, malaysiapart iii. pharmaceutical biology, 33, 262-264. allison, s. d., vitousek, p. m. 2004. rapid nutrient cycling in leaf letter from invasive plants in hawaii. oecologia,141, 612–619. anderson, j. m., ingram, j. s. i., 1993. tropical soil biology and fertilitya handbook of methods. cab international, oxon, 36-87. bazzaz, f.a., picket, s. t. a., 1980. the physiological ecology of tropical succession: a comparative review. annual review of ecology and systematics, 11, 287-310. callaway, r. m., maron, j. l. 2006. what have exotic invasions have taught us over the past 20 years?. trends in ecology and evolution, 21, 369-374 callaway, r. m., ridenour, w. m., 2004. novel weapons: invasive success and the evolution of increased competitive ability. frontiers in ecology and environment, 2, 436–443. charles, h., dukes, j. s., 2007. impacts of invasive species on ecosystem services ecological studies, in: nentwig, w. (ed.), biological invasions, springer-verlag berlin couteaux, m. m., bottner, p., berg, b. 1995. litter decomposition, climate and litter quality. trends in ecology and evolution, 10, 63-66. crooks, j. a. 2002. characterizing eco-system level consequences of biological invasions: the role of ecosystem engineers. oikos, 97, 15-166. ehrenfeld, j. g., 2003, effects of exotic plant invasions on soil nutrient cycling processes, ecosystems 6, 503–523 ehrenfeld, j. g., 2004. implications of invasive species for belowground community and nutrient processes, weed technology, 18, 1232–1235. el-shatnawi , m. k. j., makhadmeh, i. m. 2001. ecophysiology of the plantrhizosphere system: a review. journal of agronomy and crop science, 187, 1-9. facelli, j. m., pickett, s. t. a. 1991. plant litter: its dynamics and effects on plant community structure. the botanical review, 57, 1-32 geesing, d., al-khawlani, m., abba, m. l. (2004), management of introduced prosopis: can economical exploitation control an invasive species?, unasylva 217, vol 55, 6-44 (http://www. pe.wzw.tum.de/publikationen/pdf/sd 598accessed 22. 09. 2012) hirobe, m., sabang, j., bhatta, b. k. takada, h. 2004, leaf litter decomposition of 15 tree species in a lowland tropical rain forest in sarawak;decomposition rates and initial litter chemistry, journal of forest research 9, 341-346 hedley, m. j., white, r. e., nye, p. h. 1983. plant induced changes in rhizosphere of rape seedling. iv. the effects of rhizosphere phosphorous status on the ph, phosphotase activity and depletion of soil wickramathilake et al., /journal of tropical forestry and environment vol. 3, no. 02 (2013) 66-75 74 phosphorous fractions in the rhizosphere and on the cationanion balance of plants. new phytologist 95, 69-82 hess, p. l. 1971. methods of soil analysis, john murray ltd. london jayarathna, b., ranwala, s., 2010. research on invasive alien plant in sri lanka: an analysis of past work, in: marambe, b., silva, p., wijesundara, s. and atapattu, n. (eds.), invasive alien species strengthening capacity to control introduction and spread in sri lanka, biodiversity secretariat, ministry of environment, sri lanka, 179-184. jenkinson, d. s., powlson, d. s. 1976. the effects of biocidal treatments on metabolism in soilfumigation with chloroform. soil biology and biochemistry, 8, 167-177. johnny, l., yusuf, u.k., nulit, r., 2011. antifungal activity of selected plant leaves crude extracts against a pepper anthracnose fungus, colletotrichum capsici (sydow) butler and bisby (ascomycota: phyllachorales, african journal of biotechnology, vol. 10, 4157-4165. katharine m. b., scow, k. m., davies, k., f., & harrison, s. p. (2006), two invasive plants alter soil microbial community composition in serpentine grasslands, biological invasions 8, 217-230. kourtev, p. s., ehrenfeld j., g., huang, w. 2002, exotic plant species alter microbial structure and function in the soil. ecology, 85, 3152–3166. liao, c., peng, r., luo, y., zhou, x., wu, x., fang, c., chen, j., li, b., 2008. altered ecosystem carbon and nitrogen cycles by plant invasion: a meta-analysis. new phytologist, 177, 706–714. martin, m. r., tipping, p. w., and sickman, j. o. 2009. invasion by an exotic tree alters above and below ground ecosystem components. biological invasions, 11, 1883-1894 meier, c. l., bowman, w. d. 2008. phenolicrich leaf carbon fractions differently influence microbial respiration and plant growth. oecologia 158, 95-107. muleller-dombois d., ellenburg h., 1974, aims and methods of vegetation ecology, john wiley and sons, ny republished 2002 by blackburn press, ny nicholas r. j., diane l. l., sheri c. h. 2008, soil modification by invasive plants: effects on native and invasive species of mixed-grass prairies. biological invasions 10, 177–190. parker, i. m., simberloff, d., lonsdale, w. m., 1999. impact: toward a framework for understanding the ecological effects of invaders. biological invasions, 1, 3–19. pimentel, d., lach, l., zuniga, r., morrison, d., 2000. environmental and economic costs of nonindigenous specie in the united states. bioscience, 50, 53–65. prasad, a., kazemian, s., kalantari, b., . huat, b. b. k., mafian, s., 2012. stability of tropical residual soil slope reinforced by live pole: experimental and numerical investigations, arabian journal for science and engineering volume 37, number 3, 601-618. rahim, s. a., idris, w. m. r., rahman, z.a., lihan, t., omar, r., gasim, m. b., cheng, w. 2011, heavy metal content in soil environment and dillenis suffruticosa at pelepah kanan mining area, kota tnggi, johor. e-bangi: journal of social sciences and humanities, 6, 1-16. ranwala s. m. w., 2011, invasive alien plants in sri lanka (in sinhala), national science foundation, sri lanka richardson, d. m., van-wilgen, b. w. 2004. invasive alien species in south africa-how well do we understand ecological impacts. south african journal of science, 100, 45-52. robert s. b., murray, e. g. d. and nathan r. s., 1957, bergey's manual of determinative bacteriology (7 th edition), baltimore, the williams & wilkins company http://www.academicjournals.org/ajb/pdf/pdf2011/16may/johnny%20et%20al.pdf http://www.academicjournals.org/ajb/pdf/pdf2011/16may/johnny%20et%20al.pdf http://www.springerlink.com/content/?author=arun+prasad http://www.springerlink.com/content/?author=sina+kazemian http://www.springerlink.com/content/?author=behzad+kalantari http://www.springerlink.com/content/?author=bujang+b.+k.+huat http://www.springerlink.com/content/?author=sasan+mafian http://www.springerlink.com/content/n23825006743q41k/ http://www.springerlink.com/content/n23825006743q41k/ http://www.springerlink.com/content/1319-8025/ http://www.springerlink.com/content/1319-8025/ http://www.springerlink.com/content/1319-8025/37/3/ wickramathilake et al., /journal of tropical forestry and environment vol. 3, no. 02 (2013) 66-75 75 sasan, m., huat, b.b.k., barker, d.h., rahman, n.a., singh, a., 2009.live poles for slope stabilization in the tropical environment, malaysia electronic journal of geoenginering, vol. 14, http://www.ejge.com/2009/ppr0962/ppr0962.pdf accessed [17. 08. 2012]. swift, m. j., heal, o. w., anderson, j. m. 1979. decomposition in terrestrial ecosystems, studies in ecology 5, blackwell scientific publications, oxford vilà, m., weiner, j., 2004. are invasive plant species better competitors than native plant species? – evidence from pair-wise experiments. oikos 105, 229–238. vitousek, p., 1982. nutrient cycling and nutrient use efficiency. american naturalist. 119 pp. 553. walker, l. r., smith, s. d., 1997. impacts of invasive plants on community and ecosystem properties. in: luken j. o, thieret j. w,luken j. o., (eds). assessment and management of plant invasions.springer:,new york. 69–86. weerasinghe, t. k., 2012. impact of land use changes to a natural forest on some soil microbiological properties, international journal of research in biosciences (ijrbs), vol 2, november (accepted) weerasinghe, t. k., weerasinghe, h. a. s., 2007. the impact of a monoculture plantation (rubber plantation) on soil quality degradation, proceedings of iufro conference on forest landscape restoration, 14-19 may 2007, seoul, korea weidenhamer, j. d., callaway, r. m. 2010. direct and indirect effects of invasive plants on soil. chemistry and ecosystem function journal of chemical ecology, 36, 59–69. wiart, c., mogana, s., khalifah, s., mahan, m., ismail, s., buckle, m., narayana, a.k. , sulaiman, m. 2004. antimicrobial screening of plants used for traditional medicine in the state of perak, peninsular malaysia. fitoterapia, 75, 65-73. wijesundara, s., 1999. invasive alien plant in sri lanka. in: (ed. marambe b.), proceedings of the first national symposium on invasive alien species in sri lanka, ministry of forestry and environment, sri lanka wijesundara, s., 2010. invasive alien plant in sri lanka., in: marambe,b., silva,p., wijesundara,s. and atapattu, n. (eds.), invasive alien species strengthening capacity to control introduction and spread in sri lanka: biodiversity secretariat, ministry of environment, sri lanka, 27-38. yurkonis, k. a., meiners, s. j., wachholder, b. e., 2005. invasion impacts diversity through altered community dynamics. journal of ecology 93, 1053–1061. xiong, s., nilsson, c. 1999. the effects of plant litter on vegetation; a meta-analysis. journal of ecology, 87, 984 994. http://www.ejge.com/2009/ppr0962/ppr0962.pdf%20accessed%20%5b%5d 120 method validation for analysis of aroclor 1260 in transformer oil using gas chromatography – electron capture detection j.j. jeevanantham1, d.a.t.w.k. dissanayake2*, g.v.v. liyanaarachchi2, m.n.a. mubarak2, w.m.a.k. wijesinghe2 and j. k. a. b. wijegunasekara2 1college of chemical sciences, institute of chemistry ceylon, adamantane house, 341/22 kotte road, welikada, rajagiriya, sri lanka 2industrial technology institute, 363, bauddhaloka mawatha, colombo7, sri lanka. date received: 06-12-2018 date accepted: 20-12-2019 abstract since early 1980’s, the production and usage of polychlorinated biphenyls (pcbs) have been banned throughout the world due to its carcinogenicity to humans and animals. however, due to the large halflives of pcbs, large amounts of stocks are still available in storage. this study presents the validation data of the method developed for analysis of aroclor 1260 in transformer oils in order to determine the concentrations for systematic disposal and destruction. the transformer oil samples were prepared according to the astm d 4059 with few modifications. pcbs in transformer oils were extracted with iso-octane followed by deactivated florisil cleanup and detection by gc – ecd using hp 5 gc column (30 m x 0.32 mm x 0.25 μm). the study was performed under matrix matched condition to eliminate the matrix effect that was found to be significant. the method was found linear over a wide working range from 2.5 ppm – 100 ppm with a regression coefficient of 0.994 and a lower limit of determination of 2.5 ppm. method showed satisfactory repeatability with relative standard deviation below 7% over the entire working range. accuracy of the method was assured using spike recoveries at 5 ppm, 10 ppm and 50 ppm with 85%, 105% and 93% respectively. the selectivity of aroclor 1260 was confirmed against aroclor 1254 and aroclor 1242 considering uniquely identified non – overlapping chromatographic peaks. based on the performance characteristics, this method can be suggested as an accurate and precise methodology to analyze aroclor 1260 present in transformer oil. keywords: pcb, transformer oil, aroclor 1260, gas chromatography, electron capture detector. 1. introduction pcb is expanded as poly chlorinated biphenyl. pcbs are a group of synthetic organic chemicals consisting of carbon, hydrogen and chlorine atoms. the number of chlorine atoms and their location in a pcb molecule determine many of its physical and chemical properties. pcbs are also categorized as a constituent member of poly aromatic hydrocarbons (schantz, 1996). pcbs have no known taste or smell, and range in consistency from an oil to a waxy solid.the solubility of certain congeners of pcb is as low as 0.0013 ug/ml(lang, 1992) the chemical properties primarily responsible for many of the industrial applications of pcbs that is, their inflammability, chemical stability, and miscibility with organic compounds (i.e., lipophilicity), accounts for their use as thermal insulators and coolants mainly in transformers, capacitors, electrical equipment including voltage regulators, switches, re-closers, bushings, electromagnets, oils used in motors and hydraulic systems. *correspondence:thanuja@iti.lk tel: +94112379978 issn 2235-9370 print/issn 2235-9362 online ©2017 university of sri jayewardenepura doi: https://doi.org/10.31357/jtfe.v9i2.4474 jeevanantham et al. /journal of tropical forestry and environment vol. 9, no. 02 (2019), 120-131 121 pcbs were also used in fluorescent light ballasts, cable insulation, adhesives, tapes, oil-based paints, caulking, plastics, carbonless copy paper and floor finish (safe, 1994; bowman et al., 2010)(erickson and kaley, 2011). despite their wide use in industry, pcbs have been classified as a type 1 carcinogen by the international agency for research on cancer (iarc) (international agency for research on cancer, 2018). earlier, pcbs were classified as a 2b carcinogen due to the studies showing that rats developed tumors in the liver after a prolong exposure to pcbs (kamohara, yagi and itokawa, 1984; safe, 1985). however, in late 70s, there were a few accidental poisonings leading to enhanced concern on studies related to toxicity of pcbs (grittini et al., 1995). pcbs are absorbed through ingestion, inhalation, and dermal exposure, after which they are transported similarly through the circulation (schantz, 1996). sensitized individuals may develop a rash after 2 days of exposure by contact or inhalation (andric et al., 2006), and also have shown through studies that pcbs can interfere with endocrine hormones by mimicking and biding with the active site(chris, 1991). studies also have shown that pcb acts as an embryo toxic and teratogen to birds (hoffman et al., 1996) furthermore pcbs have also effected in birds since the second world war by the pattern of calcium metabolism. according to studies pcbs have made eggshells of birds thinner(lohmann and dachs, 2019). furthermore because of their persistence in the environment, the bioaccumulation in human and animal tissues (kamohara, yagi and itokawa, 1984), pcbs have also been detected in human breast milk and they have a large potential to have chronic or delayed toxicity (schantz, 1996). due to the risk of carcinogenicity, the general disposal methods are cannot be considered safe since pcbs have long half-lives (seegal et al., 2011). therefore, disposal of pcbs are carried out using specific disposal methods such as by reacting with metallic sodium and sulphate radicals can be used to break down pcb congeners(fang et al., 2012), burning of pcb in cement kilns, chemical reduction, and molten metal pyrolysis (grittini et al., 1995) etc. but in all these methods, formation of polychlorinated dioxins and furans are possible. therefore, attention must be given to minimize the formation of hazardous byproducts. furthermore studies have also been carried out on whether microorganisms could break down the pcb found in soil, by growing microorganisms in soil slurry(correa et al., 2010). in the year 2001, representatives from different countries established the stockholm convention to discuss issues and concerns regarding protection of the environment. according to this convention, 12 organic pollutants were identified as persistent organic pollutants (pops) (table 1) and polychlorinated biphenyl in one out of the twelve chemicals which were identified as (stockholm convention, 2001; onu, 2009). the signed agreement states that all parties must work towards either destruction or disposal of stocks of pcbs by the year 2025 (onu, 2009). table 1: dirty dozen of the stockholm convention(onu, 2009) chemical use aldrin pesticide (insecticide) chlordane pesticide (insecticide, termiticide) dieldrin pesticide (insecticide) ddt pesticide (insecticide) endrin pesticide (insecticide, rodenticide) heptachlor pesticide (insecticide, termiticide) mirex pesticide (insecticide, termiticide) toxaphene pesticide (insecticide) hexachlorobenzene pesticide (fungicide), by-product of solvent manufacture polychlorinated biphenyl industrial dioxin by-product furan by-product 122 since 1929 pcbs were used in transformer oils throughout the world. in the same manner pcbs were used in transformers oils in sri lanka(implementation et al., 2004)(justice and lanka, 2006). in 1979, pcbs were banned and ever since pcb was not added to transformer oils in sri lanka. in the year 2002 sri lanka signed the stockholm convention on persistent organic pollutants (pop)(stockholm convention, 2001). several methods in literature describe about analysis of aroclors in transformer oil. many authors have used expensive solid phase extraction (spe) (na et al., 2008; gordon, szlta and feeder, 1982,) or lengthy analytical procedures (shin et al., 2006) for aroclor analysis. sri lanka, as a signatory to the stockholm convention, it was a timely requirement in the country for the establishment of a simple, relatively cost effective and rapid method developed for analysis of aroclor 1260, which was the most frequently detected aroclor present in the transformers as per the preliminary assessments carried out in the country. in this relation, a simple, cost effective and a rapid method was validated for the analysis of aroclor 1260 in transformers oils. 2. methodology 2.1 materials and reagents the standard of aroclor 1260, 500 ppm in transformer oil was purchased from sigma aldrich germany. 2,2,4-trimethylpentane/ isooctane with a purity of > 99.5% gc grade (sigma aldrich germany),deactivated magnesium silicate (fisher scientific – usa), the helium and nitrogen gasses used for the analysis were of high purity of 99.999%. 2.2 instrumentation agilent 6890 series gas chromatograph coupled to electron capture detector with a hp-5(5% phenyl methyl 30 m x 0.32 mm x 0.25 μm) column was used for the analysis. inlet temperature was maintained at 250 °c in split-less mode. the aroclors were separated using a temperature programme stated at 100 °c and ended at 300 °c at a rate of 15 °c/min with a flow rate of 2 ml/min. the detector was maintained at 308 °c. 2.3 preparation of working standards series the working standards were prepared by diluting the 500 ppm aroclor 1260 to 2.5 ppm, 7.5 ppm, 25 ppm and 100 ppm concentrations in non-contaminated transformer oil. then 0.10 + 0.01 g from the prepared each working standards were extracted to 10 ml of 2,2,4-trimethylpentane according to the procedure explained in 2.4 to maintain the recommended dilution ratio of 50:1 of solvent: transformer oil. 2.4 preparation of samples 0.10 + 0.01 g of transformer oil sample was weighed in to a 10 ml glass disposable vial and diluted 50 times with 10 ml of 2,2,4-trimethylpentane to obtain a 50:1 solvent ratio. then approximately 1 g of deactivated magnesium silicate (florisil) was added and vortexed for 3 mins at 2500 rpm. the supernatant was filtered using a nylon 0.45 μm syringe filter in to a 2 ml auto sampler vial for injection into the gcecd. 2.5 reagent blanks if the reagent blank produces same set of peaks within ± 0.05 min of the retention time as of the aroclor 1260 with identical ratios observed for aroclor 1260, the source of contamination or the interference was eliminated before processing samples. 2.6 fortified samples pcb free transformer oil was spiked with aroclor 1260 to concentrations of 5 ppm, 10 ppm, and 50 ppm respectively. the same method was followed for the fortified sample in order to measure accuracy, precision and the recovery of the method. the fortified samples were replicated six times to evaluate the method performance characteristics. jeevanantham et al. /journal of tropical forestry and environment vol. 9, no. 02 (2019), 120-131 123 2.7 method validation method performance characteristics: accuracy, precision, recovery, limit of determination (lod), limit of quantification (loq) selectivity, linearity, working range were evaluated as per eurachem guidelines.(eurachem, 2014) 3. results the summary of validation data is given in table 2. table 2: results and parameters 3.1 selectivity since there are 209 pcb congeners there are a large no of peaks in the chromatogram as depicted in figure 1. this makes the identification and quantification more challenging. gc-electron capture detector was used for detection. the concentration of pcb was identified by selecting the specific peaks which are unique for aroclor1260 as denoted in figure 1. the peaks were selected by screening aroclor 1260 against aroclor 1242 and aroclor 1254 standards as given in figure 2. and figure 3. recovery % precision (%rsd) lod (ppm) loq (ppm) linearity working range (ppm) low mid high low mid high 85 +4 109 + 6 94 + 2 5.1 6.7 2.4 2.5 5 0.994 2.5 – 100 figure 2: gc chromatogram of aroclor 1260 figure 1: gc chromatogram of aroclor 1260 124 figure 2: gc chromatograms of (a) aroclor 1260 (b) aroclor 1254 and (c) aroclor 1242 jeevanantham et al. /journal of tropical forestry and environment vol. 9, no. 02 (2019), 120-131 125 figure 3: gc chromatograms of aroclor 1016 and 1260 126 figure 4: gc chromatograms of aroclor 1248 and 1260 figure 4 : gc chromatograms of aroclor 1248 and 1260 jeevanantham et al. /journal of tropical forestry and environment vol. 9, no. 02 (2019), 120-131 127 figure 5: gc chromatograms of aroclor 1232 and 1260 128 by overlaying and screening peaks of retention times of 12.9 min, 13.2 min, 13.5 min, 13.8 min, 14.3 min were obtained. it was also assured that, the selected peaks utilized for the quantification of aroclor 1260 were completely free from the interfering peaks present in other pcb congeners present in pcb 1248, 1016 and 1232 as clearly indicated in figures 3, 4 and 5. 3.2 accuracy and recovery since a certified reference material was not available, accuracy of the method was evaluated using the recovery values. the recovery of the method covering the low, mid and high quantification levels of the analytical range were as 85%, 109%, and 94% respectively. 3.3 precision the relative percentage standard deviation (% rsd) for the fortified samples obtained were 5.1%, 6.7%, and 2.4% for quantification levels at 5 ppm, 10 ppm, and 50 ppm respectively. 3.4 limit of detection (lod) and limit of quantification (loq) to the mean value obtained for the blank response fortified at the lowest detectable concentrations, the lods and the loqs evaluated for pcb by adding approximately 3 times and 5 times of the standard deviation of the response detected for the fortified blank at the lowest detectable concentrations were 2.5 ppm and 5 ppm respectively. 3.5 linearity and working range the method was found linear with a regression coefficient of 0.994 over the working range from 2.5 ppm – 100 ppm. figure 6: calibration curve for total peak area of aroclor 1260 vs concentration 4. discussion in literature, pcb analysis has been carried out mainly using non polar solvents such as hexane, dichloromethane and toluene followed by spe clean up (na et al., 2008; gordon, szlta and feeder, 1982). in comparison to the spe cleanup, the method described here uses dispersive florisil cleanup which eliminates the requirement of use of spe manifolds and is very cost effective(ballschmiter and zell, 1980). further, the method presented is quick and fast enabling screening and quantification of aroclor 1260 within 19 min which is lower than many of the methods described in literature for aroclor analysis (aries et al., 2004; frame and cochran, 1996) jeevanantham et al. /journal of tropical forestry and environment vol. 9, no. 02 (2019), 120-131 129 the method performance characteristics obtained for the analysis of pcbs in transformer o ils were evaluated in comparison to the requirements mentioned in international method validation guidelines (aoac,2012; eurachem, 2014). since unique chromatographic peaks were selected for the qualitative identification and quantitative analysis against aroclor 1242 and aroclor 1250, the selectivity of the analytical method was assured. florisil clean up enabled removal of most of the complexities associated with the mat rix. in addition, the interference arising from the matrix was further eliminated through the use of the matrix matched calibration conditions. the method was found accurate throughout the analytical range with mean recoveries found within the range from 80 – 110 % which is the recommended acceptable recovery percentages for analytes which are present in ppm ranges (aoac, 2012). the method was also found precise with mean relative standard deviations below 8%. according to the aoac guidelines for standard method performance requirements, percentage relative standard deviation should be less than 11% (aoac, 2012) for the analytes present in ppm levels. the linearity of the method was observed throughout the working range which extended from 2.5 ppm – 100 ppm. further, with low lod and loq values, the method enables sensitive detection of aroclor which could be present in trace levels in transformer oils. prior to the injection of the samples fresh transformer oil (without aroclor1260) was prepared in the same manner and injected to the gc-ecd to identify any solvent interaction between transformer oil and iso octane. furthermore the fortified samples indicated the glassware and the reagents did not affect the extraction of aroclor 1260 in the iso octane due to the recovery being between 80% 100%. therefore, all the method performance characteristics of the analytical method are in compliance with the requirements stipulated in international method validation guidelines. 5. conclusion the work described presents the method validation studies carried out on the analysis of aroclor 1260 in transformer oils. the method is accurate, precise and sensitive and hence can be used for qualitative and quantitative analysis of aroclor 1260 in transformer oil to study to the level of contamination of pcbs in transformer oils for the implementation of the national plan on phasing out of pcbs in sri lanka by 2025. acknowledgments the authors gratefully acknowledge the financial assistance granted by the industrial technology institute of sri lanka. references andric, n. l. et al. 2006. ‘effect of a pcb-based transformer oil on testicular steroidogenesis and xenobiotic-metabolizing enzymes’, reproductive toxicology, 22(1), pp. 102–110. doi: 10.1016/j.reprotox.2005.12.002. aries, e. et al. 2004. ‘development and validation of a method for analysis of “‘ dioxin-like ’” pcbs in environmental samples from the steel industry’, 54, pp. 23–31. doi: 10.1016/s00456535(03)00762-8. ballschmiter, k. and zell, m. 1980. ‘analysis of polychlorinated biphenyls (pcb) by glass capillary gas chromatography composition of technical aroclorand clophen-pcb mixtures’, fresenius’ zeitschrift für analytische chemie, 302(1), pp. 20–31. doi: 10.1007/bf00469758. bowman, j. et al. 2010. ‘preliminary assessment of polychlorinated bipheynls (pcbs), coengers, aroclors, dioxins, and furans in the sediment and soil at the united states department of energy (doe) portsmouth gaseous diffusion plant (ports), piketon, ohio’, preliminary pcb assessment, p. 63. available at: http://www.portsfuture.com/(editor)_!78/pcb assessment report_final.pdf. 130 chris, l. (1991) ‘structural analogues’, amino acids, (january), p. 1991. correa, p. a. et al. 2010. ‘the effects of individual pcb congeners on the soil bacterial community structure and the abundance of biphenyl dioxygenase genes’, environment international. elsevier ltd, 36(8), pp. 901–906. doi: 10.1016/j.envint.2009.07.015. erickson, m. d. and kaley, r. g. 2011. ‘applications of polychlorinated biphenyls’, environmental science and pollution research, 18(2), pp. 135–151. doi: 10.1007/s11356-010-0392-1. eurachem .2014. the fitness for purpose of analytical methods a laboratory guide to method validation and related topics. available at: https://www.eurachem.org/index.php/publications/guides/mv (accessed: 5 december 2018). fang, g. d. et al. 2012. ‘sulfate radical-based degradation of polychlorinated biphenyls: effects of chloride ion and reaction kinetics’, journal of hazardous materials. elsevier b.v., 227–228, pp. 394–401. doi: 10.1016/j.jhazmat.2012.05.074. frame, g. m. and cochran, j. w. 1996. ‘complete pcb congener distributions for 17 aroclor mixtures determined by 3 hrgc systems optimized for comprehensive , quantitative , congenerspecific analysis’, pp. 657–668. gordon, r. j., szlta, j. and feeder, e. j. 1982. ‘determination of polychlorinated biphenyls in transformer oils by capillary gas chromatography’, analytical chemistry, 54(3), pp. 478–481. doi: 10.1021/ac00240a028. grittini, c. et al. 1995. ‘rapid dechlorination of polychlorinated biphenyls on the surface of a pd/fe bimetallic system’, environmental science & technology. american chemical society, 29(11), pp. 2898–2900. doi: 10.1021/es00011a029. hoffman, d. j. et al. 1996. ‘in nestling american kestrels ( falco sparverius )’, 0(0189), pp. 188–200. iarc (international agency for research on cancer) (2018) ‘agents classified by the iarc monographs, volumes 1-121’, iarc monographs, (000050), pp. 1–25. doi: 10.1007/s13398014-0173-7.2. implementation, n. et al. 2004. under the stockholm convention on pops for sri lanka. justice, e. and lanka, s. 2006. ‘country situation on persistent organic pollutants ( pops ) in india’, 2(march). kamohara, k., yagi, n. and itokawa, y. 1984. ‘mechanism of lipid peroxide formation in polychlorinated biphenyls (pcb) and dichlorodiphenyltrichloroethane (ddt)-poisoned rats’, environmental research, 34(1), pp. 18–23. doi: 10.1016/0013-9351(84)90071-9. lang, v. 1992. ‘polychlorinated biphenyls in the environment’, journal of chromatography a, 595(1–2), pp. 1–43. doi: 10.1016/0021-9673(92)85144-i. lohmann, r. and dachs, j. 2019. ‘polychlorinated biphenyls in the global ocean’, world seas: an environmental evaluation, 220, pp. 269–282. doi: 10.1016/b978-0-12-805052-1.00017-6. na, y. et al. 2008. ‘chemosphere determination of polychlorinated biphenyls in transformer oil using various adsorbents for solid phase extraction’, 73. doi: 10.1016/j.chemosphere.2006.12.102. onu 2009. ‘stockholm covention on persistent organic pollutants (pops)’, secretariat of the stockholm convention on persistent organic pollutants, p. 56. available at: http://www.wipo.int/edocs/lexdocs/treaties/en/unep-pop/trt_unep_pop_2.pdf. jeevanantham et al. /journal of tropical forestry and environment vol. 9, no. 02 (2019), 120-131 131 reiter, e. v. et al. 2011. ‘uncertainty from sampling in measurements of aflatoxins in animal feedingstuffs: application of the eurachem/citac guidelines’, the analyst. the royal society of chemistry, 136(19), p. 4059. doi: 10.1039/c1an15124j. safe, s. 1985. ‘polychlorinated biphenyls (pcb s) and polybrominated biphenyls (pbb s): biochemistry, toxicology and mechanisms of action’, 13(4). safe, s. h. 1994. ‘polychlorinated biphenyls (pcbs):environmental impact, biochemical and toxic responses, and implications for risk assessment’, critical reviews in roxicology, 24(2), pp. 87–149. schantz, s. l. 1996. ‘developmental neurotoxicity of pcbs in humans: what do we know and where do we go from here?’, neurotoxicology and teratology, 18(3), pp. 217–227. doi: 10.1016/s08920362(96)90001-x. seegal, r. f. et al. 2011. ‘estimating the half-lives of pcb congeners in former capacitor workers measured over a 28-year interval’, journal of exposure science and environmental epidemiology. nature publishing group, 21(3), pp. 234–246. doi: 10.1038/jes.2010.3. shin, s.k. et al. 2006. 'levels of polychlorinated biphenyls (pcbs) in transformer oils from korea', journal of hazardous materials , 137, 1514–1522. stockholm convention 2001. ‘persistentent organic polutants and the stockholm convention : a resource guide’, resource futures international for the world bank and cida, (september), pp. 1–24. available at: http://worldbank.org/intpops/2145741115813449181/20486510/persistentorganicpollutantsaresourceguide2001.pdf. chapter 3 gunarathne & perera /journal of tropical forestry and environment vol 4, no 01 (2014) 14-27 14 die-out of manilkara hexandra from bundala national park, sri lanka: causes and some possible underlying mechanisms r.m.u.k. gunarathne 1,2 and g.a.d. perera 1,2* 1 postgraduate institute of science, university of peradeniya, peradeniya, sri lanka 2 department of botany, university of peradeniya, peradeniya, sri lanka date received: 08-12-2013 date accepted: 31-03-2014 abstract bundala national park (bnp) is a biologically diverse wetland habitat where a sizable area of tropical semi-deciduous (tsd) forests of sri lanka exists. manilkara hexandra is the only dominant canopy tree species in these forests. however, the species appears to be dying out from bnp. with the aim of revealing the causes and possible underlying reasons for the die-out of the species, the population size, spatial distribution, natural regeneration and the healthiness of individuals of m. hexandra in bnp were examined in twenty five 50x50 m 2 plots in three-belt transects which were established across different forest categories in bnp. the major alien exotic plants in these plots were also enumerated. results revealed that the tree die-back and poor natural regeneration were among the major causes for the die-out of m. hexandra from bnp, which had altered the population structure and distribution of the species over space. live individuals of the species were absent in some degraded sites especially those invaded by prosopis juliflora. presence of over-mature cohorts, occurrence of tree cankers and presence of the aggressive invader, p. juliflora appear to affect the die-back of m. hexandra. this study provides a clue that there is a possibility of dying-back of the remaining healthy trees of m. hexandra in tsd forests of bnp in the near future, unless the threats imposed upon m. hexandra are uplifted through strategic management activities. key words: invasion, natural regeneration, population structure, tree cankers, tropical semideciduous forest ___________________________________________________________________________ 1. introduction dying out of species is recorded as a major threat to the tropical biodiversity and has been reported from many tropical ecosystems in the world (whitmore & sayer, 1992). habitat alterations and loss, over-harvesting, species and disease introduction, pollution and climate change have been cited as major direct or proximate causes which lead to the loss of plant and animal species, possibly to their extinction. among these, habitat alteration is clearly a predominant cause and is a problem that operates mainly at the local level (wood et al., 2000). the die-back of populations of tree species is increasingly being heard as a way of habitat alterations and consequent possible loss of given species. however, the underlying causes for forest or tree die-back may vary with the region or the site. air pollution has often been reported as the cause for forest die-back in many areas of the temperate regions of the world (smith, 1981; hinrichsen, 1986, 1987; vries et al., 2000). * correspondence: anomap@pdn.ac.lk tel: +94 812394520 issn 2235-9370 print/issn 2235-9362 online © university of sri jayewardenepura http://www.cabdirect.org/search.html?q=ed%3a%22whitmore%2c+t.+c.%22 http://www.cabdirect.org/search.html?q=ed%3a%22sayer%2c+j.+a.%22 mailto:anomap@pdn.ac.lk gunarathne & perera /journal of tropical forestry and environment vol 4, no 01 (2014) 14-27 15 the acid rain produced due to air pollution is often cited as a major cause for the forest dieback (vogelmann et al., 1985; pitelka and raynal, 1989; kandler & innes, 1995). for instance, the atmospheric sulfur dioxide concentration was very high in the ore mountains of northern bavaria, germany where the forest decline was reported to be very severe (prinz, 1985). acid rains may enhance soil acidification and subsequent aluminum toxicity in plants (ulrich, 1983). however, extreme climatic conditions (auclair, 1993) especially temperature (frost formation) and drought stresses are also reported to cause forest declines (fensham & holman, 1999; vries et al., 2000) or to contribute to the synchrony of the declines (prinz, 1985; blank, 1986). in addition, redmond (1955) has reported that the death of yellow birch (betula sp.) trees may be due to the growth of cylindroporium sp. in the soil at elevated soil temperatures and the subsequent suppression of mycorrhizal fungi in the rhizosphere. on the other hand, forest die-back in the tropical regions of the world often appears as occurring due to extreme climatic conditions, especially due to extreme drought conditions (auclair, 1993) or due to the climate change (mueller-dombios, 1980). for instance, prolonged drought is reported as a major underlying cause for forest die-back in both mudumalai dry forests in southern india (suresh et al., 2010) and in savanna forests in queensland, australia (rice et al., 2004), while the el niño drought events are reported to cause forest die-back in tropical rain forests of north of manaus, brazil (laurance et al., 2001) and in north east australia (rice et al., 2004). changes in soil chemical composition (ulrich et al., 1980) or soil nutrient imbalances (mader & thompson, 1969; gerrish et al., 1988; schulze, 1989; turner and lambert, 2005; mueller-dombois, 1990) have also been identified as creating a stress situation in plants ultimately resulting in plant death. for instance, it is reported that the die-back of metrosideros polymorpha dominant rain forests has been due to soil nutrient stresses (jacobi, 1983; mueller-dombios, 1990). plants weakened due to soil nutrient imbalances would frequently be attacked by secondary agents such as insects (papp et al., 1979; johnson & mclaughlin, 1986; bauce & allen, 1992) and pathogens (hibber, 1964; papp et al., 1979; carey et al., 1984; mueller-dombois, 1986; bauce & allen, 1992; sankaran et al., 2005). similarly, long-term accumulation of nitrogen in the soils of eucalypt forests in australia has resulted in increased amino acid contents in eucalypt leaves and the subsequent increased herbivory (turner & lambert, 2005). although the die-back of m. hexandra in bundala national park (bnp), sri lanka has been reported (bambaradeniya et al., 2002), the causes and underlying mechanisms for this tree die-back have not yet been revealed. m. hexandra is a dominant canopy tree species in dry forests of sri lanka but the natural regeneration of the species is recorded to be very poor (holmes, 1956). the species is reckoned to be the sole dominant canopy species in tropical semi-deciduous forests at bnp, where it is severely dying-out (perera, 2012). dead trees of the species are seen especially closer to lagoons and inland water bodies. the alien exotic, prosopis juliflora had invaded such affected areas forming p. juliflora dominant degraded forest stands. however, the vegetative and reproductive phenological events in the remaining live individuals of m. hexandra in the area have not been affected and mass fruiting takes place in every 3-4 years (gunarathne & perera, 2014). m. hexandra is the only species affected in bnp and this implies that the causes for tree die-back may be rather species specific. it is vital to investigate carefully and methodically the reasons behind the die-back of this sole dominant canopy species in order to prepare guidelines for conservation of the species and for the management of the affected areas. the study of the population distribution and the magnitude and nature of die-back disturbance is therefore of prime importance in both planning further research and managing the area. therefore, a detailed survey of the population of m. hexandra in bnp was conducted gunarathne & perera /journal of tropical forestry and environment vol 4, no 01 (2014) 14-27 16 with the aim of revealing the causes and possible underlying reasons behind the die-out of the population of m. hexandra in bnp by assessing the spatial variation in the population structure (based on density, dbh and height), the natural regeneration of the species and the tree healthiness. 2. materials and methods 2.1 study area and the climate the bundala national park lies along the south coast of hambantota district in the low country dry zone of sri lanka (6 0 08’6 0 14’n, 81 0 08’81 0 18’e) (fig. 1). the park area extends over an area of 3,698.01 ha (gazette notice 28 th july 2004). four shallow brackish water lagoons are situated in the park (from west to the east), namely, koholankala, malala, embilikala and bundala. in general, a hot and dry climate prevails in the area with an average annual rainfall of 1059 mm (gunarathne & perera, 2014). the rainfall pattern is related to the monsoon periods and the area receives the highest rainfall around november during the north-east monsoon period. there are two distinct dry seasons per year; a short dry season from february to march and a long dry season from may to august or september. the average annual temperature in the study area during the period from 1995 to 2008 was 27.8 0 c with the mean maximum and mean minimum monthly temperatures of 35.7 0 c and 22.9 0 c, respectively. the average monthly relative humidity of the area varies around 70-80% (gunarathne & perera, 2014). fig. 1: bundala national park depicting the locations of the study sites. vegetation tropical semi-deciduous (tsd) forests in which the forest canopy comprised m. hexandra alone are the typical native forest vegetation in bnp (perera, 2012). however, the park area appears to be disturbed by different ways from time to time. some parts, especially gunarathne & perera /journal of tropical forestry and environment vol 4, no 01 (2014) 14-27 17 the northern and central parts of the park (e.g. site a in fig. 1) have been disturbed in the 1970s due to shifting cultivation and by selective logging (personal communication with the park officers and local villagers) and other continuous animal and anthropogenic activities. all these ultimately resulted in the formation of scrub jungles (sj) with scattered remnant m. hexandra trees and maintained these at a plagioclimax state (perera, 2012). four forest vegetation types can be visually identified in the southern part of bnp (in site b) by the differences in their vegetation structure and physiognomy. of these, tsd forests occur as small patches but the forests surrounding these are degraded with many dying-back trees of m. hehandra. such degraded tropical semi-deciduous (dtsd) forests are rather open with more light demanding understorey species such as azima tetracantha and ziziphus oenoplia though they are as tall as tsd forests. degraded shrublands (ds) occur adjacent to dtsd forests and are dominated by species like a. tetracantha, cassia auriculata, dichrostachys cinerea and flueggea leucopyrus but, m. hexandra is either very rare or absent in these. prosopis juliflora dominant (pd) forest stands which occur closer to lagoons and inland water bodies and contain very few plant species. of these, a. tetracantha, opuntia dillenii and salvadora persica are some commonly occurring species in these forest stands. selection of study sites with the aid of aerial photographs of the area taken in 1957, 1971 and 1981 (survey department of sri lanka) and by a reconnaissance survey, two study sites were selected for the study. sjs with scattered m. hexandra that maintained as a plagioclimax vegetation at the northern part of the bundala lagoon (site a) extending over 38 ha and relatively undisturbed tsd forests and adjacent degraded forest patches at the southern part of the park (site b) extending over an area of 36 ha (fig. 1) constitute these study sites. establishment of belt transects and enumeration of individuals of m. hexandra three 50 m wide belt transects were established at randomly chosen points in the two selected study sites. as the sj in the site a appeared more or less homogenous, only one 50 m wide belt transect was established at the site on a randomly chosen location along the eastwest direction. two transects were established at site b, one across a vegetation gradient from pd forest stands to relatively undisturbed tsd forests along the north-south direction, passing through dss and dtsd forests while the other along the east-west direction crossing at a randomly selected point perpendicular to the first belt transect. all the established belt transects in the two sites were sub-divided into 50x50 m 2 experimental plots and thus, 2 experimental plots were located in the pdf stand, 5 plots in dss, 4 plots in hdts forest, 6 plots in tsd forest in site b while 8 plots were located in sjs in site a. individuals of m. hexandra in each experimental plot were enumerated and tagged. the height of individuals which were taller than 4 m was measured using a clinometer (suunto pm-5), while the individuals shorter than 4 m were measured using a calibrated pole. tree diameter at breast height (dbh) was measured using a dbh tape (lufkin ® executive thinline, w606pm) if the dbh of individuals was >2 cm. the abundance of dreadful invader, p. juliflora was estimated in circular plots of 15 m radius which established around each mature individual (dbh >2 cm) of m. hexandra, while the frequency of occurrence of opuntia dillenii in these circular plots was recorded. in pdf stands and in dss where m. hexandra trees were absent, 3-4 circular plots were established at randomly chosen locations and the abundance of p. juliflora and the presence/absence of o. dillenii in these were recorded. healthiness of individuals of m. hexandra present in the study site was observed and recorded using a 5 point scale, modified from mclaughlin et al. (1992) (table 1). gunarathne & perera /journal of tropical forestry and environment vol 4, no 01 (2014) 14-27 18 table 1: five point tree die-back scale used to classify the healthiness of m. hexandra trees. 3. results 3.1 structure of the population of m. hexandra in the study area results revealed that the density of the live individuals of m. hexandra significantly varied among the different forest categories studied (table 2; kruskal-wallies test: p=0.002). the density of m. hexandra trees in sjs at the site a is somewhat different from that in site b as the site a contains a fewer number of m. hexandra trees with a fewer number of dead stumps. table 2: density of m. hexandra in different forest vegetations of bnp (individuals of all sizeclasses were considered). site forest category density of individuals of m. hexandra (ha -1 ) live dead a scrub jungles 14 1 b prosopis dominant forest stands 0 28 b degraded shrublands 1 25 b degraded tropical semideciduous forests 21 39 b relatively undisturbed tropical semi-deciduous forests 58 7 the highest density of m. hexandra was recorded in tsd forests in the site b. there were many dead trees of m. hexandra in pd forest stands, ds and in dtsd forests. notably, there was not a single live m. hexandra tree in pd forest stands while a few occasionally scattered m. hexandra trees were found in ds located adjacent to pd forest stands, despite that there were many dead and fallen trees of m. hexandra in these two forest stands (table 2). fig. 2 depicts the dbh distribution of m. hexandra in different forest stands in bnp. the majority of live individuals (87%) of m. hexandra in both study sites (a and b) was large and had a dbh above 22 cm (fig. 2). fig. 2 further shows that the dbh distribution of m. hexandra in all sub-populations was highly distorted due to the absence of smaller individuals of the species. for instance, the density of individuals having a dbh <2.0 cm was 2 per ha while those having a dbh within the range 2.1-22.0 cm was 3 per ha. in contrast, the density of individuals of which the dbh was >22 cm was as high as 27 per ha. the height-class distribution of the species showed that a majority of the individuals have reached the canopy and were taller than 7 m (fig. 3). the density of individuals shorter than 2 m varied from 1-3 per ha (fig. 3). health category symbol used to denote the health category scale healthy h ≤15% crown die-back or defoliation trace level die-back tld 16-25% crown die-back or defoliation low level die-back lld 26-50% crown die-back or defoliation moderate level die-back mld 51-75% crown die-back or defoliation severe die-back sd ≥76% crown die-back or defoliation gunarathne & perera /journal of tropical forestry and environment vol 4, no 01 (2014) 14-27 19 fig. 2. diameter-class distribution of live individuals of m. hexandra in (a) ds, (b) dtsd forests (c) tsd forests and (d) sj forests (pd forest stands are not included here as these forests do not contain any live individuals of m. hexandra). 3.2 healthiness and tree die-back of m. hexandra in different forest categories it is evident from fig. 4 that both saplings and mature individuals can be affected by the tree die-back. however, seedlings (<2 cm dbh) with die-back symptoms were not found in the study area. the experimental plots established at dss contained only one seedling of m. hexandra but no individuals of the species with dbh>2 cm were not found from this forest type. moreover, a lower fraction of individuals in relatively undisturbed tsd forest showed dying-back symptoms compared to dtsd and sj forests. fig. 5 shows the occurrence of die-back symptoms in m. hexandra (where the dbh >2 cm) in different forest categories as per table 1. about a half (50%) of the individuals of m. hexandra in relatively undisturbed tsd forest stands was in a healthy condition but the remainder showed die-back symptoms to different degrees. majority of these unhealthy individuals exhibited 16-50% crown die-back or defoliation (i.e., exhibiting die-back symptoms at trace or low levels). in contrast, most of the live trees (nearly 90%) in dtsd forests showed tree die-back symptoms to various degrees and only around 10% of individuals of m. hexandra in dtsd forests were healthy by the time of sampling. moreover, no live m. hexandra tree with dbh >2 cm was found in both ds and pd forest stands. (a) 0 5 10 15 20 2 .0 ≥ 2 .1 -1 2 .0 1 2 .1 -2 2 .0 2 2 .1 -3 2 .0 3 2 .1 -4 2 .0 4 2 .1 -5 2 .0 5 2 .1 -6 2 .0 6 2 .1 ≤ (b) 0 5 10 15 20 2 .0 ≥ 2 .1 -1 2 .0 1 2 .1 -2 2 .0 2 2 .1 -3 2 .0 3 2 .1 -4 2 .0 4 2 .1 -5 2 .0 5 2 .1 -6 2 .0 6 2 .1 ≤ (c) 0 5 10 15 20 2 .0 ≥ 2 .1 -1 2 .0 1 2 .1 -2 2 .0 2 2 .1 -3 2 .0 3 2 .1 -4 2 .0 4 2 .1 -5 2 .0 5 2 .1 -6 2 .0 6 2 .1 ≤ (d) 0 5 10 15 20 2 .0 ≥ 2 .1 -1 2 .0 1 2 .1 -2 2 .0 2 2 .1 -3 2 .0 3 2 .1 -4 2 .0 4 2 .1 -5 2 .0 5 2 .1 -6 2 .0 6 2 .1 ≤ n u m b e r o f in d iv id u a ls ( p e r h a ) diameter-class (cm) gunarathne & perera /journal of tropical forestry and environment vol 4, no 01 (2014) 14-27 20 fig. 3: height-class distribution of live individuals of m. hexandra in (a) ds, (b) dtsd forests (c) tsd forests and (d) sj forests (pd forest stands are not included as these forests do not contain any live m. hexandra trees). the sj in site a is somewhat different from the rest of the forest stands and the majority of individuals (nearly 90%) in it was alive and healthy. those showing die-back symptoms also exhibited crown die-back or defoliation to trace or low levels. 3.3 threats to the population of m. hexandra in the study area as given in table 3, the percentage occurrence of dead and dying back trees in examined vegetation types was significantly different (p=0.001 and p=0.002, respectively) and there were no live trees of the species where dbh > 2 cm in both pd forest stands and in dss. similarly, the density of the aggressive invader, p. juliflora varied significantly among different forest types (p=0.001) and a weak correlation exists between the density of p. juliflora trees the dead and dying-back m. hexandra trees (pearsons correlation test, r 2 =0.343). the density of p. juliflora was higher in pd forest stands and ds but lower in dtsd forests. although no p. juliflora trees were recorded within experimental plots established in sj, several individuals of this species were found to be growing adjacent to the established experimental plots. (a) 0 5 10 15 20 25 30 35 40 45 2 .0 ≥ 2 .1 -3 .0 3 .1 -4 .0 4 .1 -5 .0 5 .1 -6 .0 6 .1 -7 .0 7 .1 -8 .0 8 .1 ≤ (b) 0 5 10 15 20 25 30 35 40 45 2 .0 ≥ 2 .1 -3 .0 3 .1 -4 .0 4 .1 -5 .0 5 .1 -6 .0 6 .1 -7 .0 7 .1 -8 .0 8 .1 ≤ (c) 0 5 10 15 20 25 30 35 40 45 2 .0 ≥ 2 .1 -3 .0 3 .1 -4 .0 4 .1 -5 .0 5 .1 -6 .0 6 .1 -7 .0 7 .1 -8 .0 8 .1 ≤ (d) 0 5 10 15 20 25 30 35 40 45 2 .0 ≥ 2 .1 -3 .0 3 .1 -4 .0 4 .1 -5 .0 5 .1 -6 .0 6 .1 -7 .0 7 .1 -8 .0 8 .1 ≤ n u m b e r o f in d iv id u a ls ( p e r h a ) height-class (m) gunarathne & perera /journal of tropical forestry and environment vol 4, no 01 (2014) 14-27 21 fig. 4: proportional abundance of healthy and dying-back individuals of m. hexandra in relation to the respective tree diameter size classes in (a) ds, (b) dtsd forests (c) tsd forests and (d) sj forests in bnp. fig. 5: proportional abundance of individuals of m. hexandra whose dbh ≥ 2 cm at examined different forest categories in bnp under healthiness/die-back symptom categories as given in table 1. (a) 0 20 40 60 80 100 2 .0 ≥ 2 .1 -1 2 .0 1 2 .1 -2 2 .0 2 2 .1 -3 2 .0 3 2 .1 -4 2 .0 4 2 .1 -5 2 .0 5 2 .1 -6 2 .0 6 2 .1 ≤ (b) 0 20 40 60 80 100 2 .0 ≥ 2 .1 -1 2 .0 1 2 .1 -2 2 .0 2 2 .1 -3 2 .0 3 2 .1 -4 2 .0 4 2 .1 -5 2 .0 5 2 .1 -6 2 .0 6 2 .1 ≤ (c) 0 20 40 60 80 100 2 .0 ≥ 2 .1 -1 2 .0 1 2 .1 -2 2 .0 2 2 .1 -3 2 .0 3 2 .1 -4 2 .0 4 2 .1 -5 2 .0 5 2 .1 -6 2 .0 6 2 .1 ≤ (d) 0 20 40 60 80 100 2 .0 ≥ 2 .1 -1 2 .0 1 2 .1 -2 2 .0 2 2 .1 -3 2 .0 3 2 .1 -4 2 .0 4 2 .1 -5 2 .0 5 2 .1 -6 2 .0 6 2 .1 ≤ healthy dying back 0 20 40 60 80 100 dtsd forests tsd forests sj forest category p r o p o r ti o n a l a b u n d a n c e e h tld lld mld sd p r o p o r ti o n a l a b u n d a n c e diameter-class (cm) gunarathne & perera /journal of tropical forestry and environment vol 4, no 01 (2014) 14-27 22 opuntia dillenii is another common invasive plant in bnp and the frequency of occurrence of o. dillenii varied significantly among different forest types (p= 0.003). the species thrives luxuriantly in more disturbed forest vegetations. thus, the species is very common in dss, pd forest stands and in sj forests (table 3). the species was not found in relatively undisturbed tsd forest plots with an exception at the edges of tsd forests or by the sides of roads. visually observable common diseases of m. hexandra included the ganoderma infection and canker disease. fruiting bodies of ganoderma sp. were entirely found on dead individuals of m. hexandra but not on live trees (table 3). there were many dead or fallen trees in the ds and pd forest stands and these contained many fruiting bodies of ganoderma sp. in contrast, tree canker disease appeared as a major threat to the individuals of m. hexandra in the study area and more than 80% of individuals in bnp bear tree cankers (table 3). these were found to be occurred on any large individuals of m. hexandra irrespective of the forest type (p=0.927). cankers were present on the stem, branches or at the base of the trunks of m. hexandra trees but those on branches and stems were more prominently found in all forest types. table 3: analysis of major threats to m. hexandra in bnp. type of threats forest type pd forest stand ds dtsd forests tsd forests sj % of dead m. hexandra trees 100 98(±2) 60(±15) 8(±3) 7(±7) % occurrence of dying-back trees of m. hexandra 0 0 93(±7) 50(±11) 13(±11) density of p. juliflora (per ha) 132(±30) 134(±27) 19(±7) 1(±1) 0 frequency of occurrence of o. dillenii (%) 5(±5) 54(±16) 11(±5) 6(±6) 94(±4) live m. hexandra trees with ganoderma fruiting bodies (%) --0 0 0 dead m. hexandra trees with ganoderma fruiting bodies (%) 35(±35) 42(±17) 27(±5) 4(±4) 0 live m. hexandra trees with cankers (% ) --86(±9) 83(±5) 82(±9) 4. discussion die-out of m. hexandra, the sole canopy dominant tree in tsd forests in bnp, was evident from this study and it may be imposing a severe threat to this wetland ecosystem. around 68% of the individuals in the population of m. hexandra in bnp are either already dead or dying-back at present. tsd forests extend over a restricted area in sri lanka and bnp is the main example for such forests. therefore, the death of m. hexandra trees in bnp is a serious threat leading to the loss of sri lankan biodiversity. deflected natural regeneration and die-back of m. hexandra trees are the major causes for the die-out of the species. as a result, the population structure and spatial distribution of m. hexandra in bnp have been altered. the density of m. hexandra in the study area varies over space and it is higher in relatively undisturbed tsd forests and dtsd forest patches than in the rest of the forest gunarathne & perera /journal of tropical forestry and environment vol 4, no 01 (2014) 14-27 23 types. both natural and anthropogenic disturbances and deflected natural regeneration may be the responsible reasons for this variation, in addition to the tree die-back. for instance, sj plagioclimaxes contain a fewer number of mature individuals of the species (12 individuals ha -1 ) compared to the aforementioned two forest types. among other reasons, this can be due to the shifting cultivation and selective logging implemented in this area in the past. in contrast, dss and pdf stands contain a few or no individuals of the species and a direct cause for this may be the severe die-back of trees in this area in the recent past. presence of dead trees and fallen logs of m. hexandra provide a good evidence for its dominance in such areas in the past. as a result, the density and the diameter distribution of m. hexandra in examined vegetation types have been altered and varied spatially. in addition, the deflected natural regeneration also contributes to the low density of m. hexandra in all the examined forest categories. small individuals of which the dbh <2 cm were lacking in all the examined forest stands in bnp. this has been previously observed by holms (1956) in other parts of the country. this poor natural regeneration may be due to seed and seedling predation or constraints associated with seed germination (perera, 2007 b ). however, there are no anomalies in the production of fruits of this species within bnp and mass fruiting occurs in every 3-4 years when the climate favours towards fruit production (gunarathne & perera, 2014). the size-class distribution of m. hexandra population explained as a diameter-class distribution, in all studied forest stands is highly distorted. as ogden (1970) explained, ageclass distribution which is used as a basic component of describing animal populations may not suit to describe the plant populations, as the age distribution in plants is less significant than size distribution. therefore, in the current study, the density and size-class distributions of m. hexandra were examined to explain the impacts of tree die-back and deflected natural regeneration on the population structure of m. hexandra in bnp. m. hexandra is reported to have a slow growth rate in terms of diameter increment (holmes, 1956; rutnum, 1959; wijesinghe, 1959; de rosayro, 1961; fernando, 1962). however, it reaches a significant height (7-8 m) within a short period of time (within 8-10 years) as this light demanding canopy species has a habit of occupying the forest canopy as quickly as possible. therefore, it is impossible to relate the tree height to the age but, the diameter of individuals of the species is somewhat comparable to their age than to their height. the largest individuals of m. hexandra in bnp had stems with >50 cm dbh and 26% of trees of m. hexandra in bnp falls into this category. therefore, by considering the diameter distribution of individuals, it can be assumed that many of the individuals in the population are over-mature. the presence of over-mature cohorts in the population of m. hexandra has also been previously recorded from other parts of sri lanka and die-back of these is not an uncommon scene (de rosayro, 1961). over-mature trees are easily attacked by pests and pathogens (goheen & hansen, 1993). die-back symptoms have not been observed in seedlings and this may be due to the fact that these are somewhat resistant to tree die-back or they may die quickly without leaving any trace. the low dying-back records of trees in sjs may be due to the low density of the individuals of m. hexandra and subsequent low competition for resources, low density of invasive p. juliflora or due to the fact that diseased or unhealthy trees have already been removed in the past when the area was logged selectively or under shifting cultivation. however, in bnp, die-back does occur in mature individuals irrespective of their size and this implies that some other factors such as the presence of tree cankers or the heavy competition by invasive plants may influencing the death of m. hexandra trees in bnp in addition to the presence of old cohorts. gunarathne & perera /journal of tropical forestry and environment vol 4, no 01 (2014) 14-27 24 tree cankers appear as the most common visually observed disease symptoms in m. hexandra trees in bnp. tree cankers were found on >80% of live individuals in bnp and tend to be found everywhere irrespective of the vegetation category. cankers were found on stems, base of stems or on branches, however, branch cankers tend to form more frequently. monkeys inhabiting the park may damage twigs which cause to form wounds (gunarathne & perera, 2014) and the canker forming microorganisms, especially fungi species such as nectria sp. (perera, 2007 a ) may enter through such wounds. cankers may weaken the plant and obstruct the water movements through the stem and therefore, shoots of plants with cankers may experience water scarcity especially during drought periods. invasion of the alien exotic p. juliflora may also be a reason for the die-out of m. hexandra from bnp. on the one hand, the allelopathic chemicals present in p. juliflora may suppress seedlings of m. hexandra, if any. it has been found that the root extracts of p. juliflora inhibited the radical growth of mung bean (vigna radiata), black gram (v. mungo) and of some native forest plants (perera et al., 2009). on the other hand, this fast growing invader may compete with mature m. hexandra trees for available resources, especially for water during drought periods (gunarathne & perera, unpublished data). p. juliflora has been reported to have highly dispersed root systems (pasiecznik et al., 2001) which may extend up to about 50 m in the soil (raven et al., 2005). mwangi & swallow (2005) have also reported that lands invaded by p. juliflora in kenya suffered from water stress as they draw water efficiently from the ground water table. the lack of live m. hexandra trees and/or the presence of dead m. hexandra trees in dss and pdf stands provide a strong evidence that the death of m. hexandra may be a result of the invasion by p. juliflora. opuntia dillenii is another invasive species which has spread over a significant area in bnp, but the current study reveals that it has no link to the tree die-back of m. hexandra. for instance, the density of o. dillenii was very high in sj where the die-back incidences were low. unlike p. juliflora, o. dillenii has a surface spreading root system and may not compete with m. hexandra for water during drought periods. ganoderma infection is not a causal factor for the tree death of m. hexandra in bnp though these fungal species have been reported to as attacking many economically important tropical plant species (sankaran et al., 2005). in bnp, fruiting bodies of ganoderma sp. were found only on dead trees but not on live trees and more commonly found in pdf stands and in adjacent dss as these two forest types contained higher proportional abundance of dead trees than other forest types. conclusion tree die-back and poor natural regeneration are the direct causes for die-out of m. hexandra in bnp, which has significantly altered the population structure and the spatial heterogeneity of m. hexandra. the possible underlying reasons for this tree die-back include the invasion by p. juliflora and the subsequent increased competition for resources, presence of over-mature cohorts and the canker disease. however, ganoderma infection and the invasion by o. dillenii may not be imposing a severe threat leading to the die-out of m. hexandra from bnp. currently, around 50% of the individuals in the relatively undisturbed tsd forests show die-back symptoms but it is possible to degrade further to form shrublands unless precautions are taken to halt tree die-back. as p. juliflora is progressively invading the land, m. hexandra trees in the remaining tsd forests are at a high risk of elimination and thereby the complete devastation of tsd forests in bnp. gunarathne & perera /journal of tropical forestry and environment vol 4, no 01 (2014) 14-27 25 acknowledgements this study was funded by the department of wildlife conservation (dwc), sri lanka (grant no.: pam & wcp/dwc/research/14). authors wish to thank mr. sisira de silva, park warden of bnp and the officers of dwc; prof. n.k.b. adikaram, univerisy of peradeniya; dr. m. nugaliyadda of department of agriculture, nuwara eliya; prof. g. senevirathna, institute of fundamental studies, kandy; mr. kosala samarasinghe, mr. milinda bandara, mr. lalith wasantha and ms. wathsala for the support extended to conduct this study. references auclair, a.n.d., 1993. extreme climatic fluctuations as a cause of forest dieback in the pacific rim. water, air and soil pollution, 66:207-229. bambaradeniya, c.n.b., ekanayake, s.p., fernando, r.h.s.s., perera, w.p.n., somaweera, r., 2002. a biodiversity status profile of bundala national park: a ramsar wetland in sri lanka. occasional papers of iucn sri lanka, no. 2: iii. bauce, e., allen, d.c., 1992. role of armillaria calvescens and glycobius speciosus in a sugar maple decline. canadian journal of forest research, 22:549–552. blank, l.w. (1986). deterioration, but some recovery. nature, 319:529 carey, a.c., miller, e.a., geballe, g.t., wargo, p.m., smith, w.h., siccama, t.g., 1984. armillaria mellea and decline of red spruce. plant disease, 68:794-795. de rosayro, r.a., 1961. the nature and the origin of secondary vegetational communities in ceylon. ceylon forester, 5:23-46. fensham, r.j., holman, j.e., 1999. temporal and spatial patterns in drought-related tree dieback in australian savanna. journal of applied ecology, 36:1035-1050. fernando, d.f.s., 1962. computation of girth increment rates for dry zone species – satin, ebony, milla and palu. ceylon forester, 5:191-192. gerrish, g., mueller-dombois, d., bridges, k.w., 1988. nutrient limitation and metrosideros forest dieback in hawaii. journal of ecology, 69:723-727. goheen, d., hansen, e., 1993. effects of pathogens and bark beetles on forests, in: schowalter, t.d., filip, g.m. (eds.), beetlepathogen interactions in conifer forests. academic press, london, pp.175-196. gunarathne, r.m.u.k., perera, g.a.d., 2014. climatic factors responsible for triggering phenological events in manilkara hexandra (roxb.) dubard., a canopy tree in tropical semi-deciduous forest of sri lanka. tropical ecology, 55:63-73. hibber, c.r., 1964. identify and significance of certain organisms associated with sugar maple decline in new york woodlands. phytopathology, 74:1389-1392. hinrichsen, d., 1986. multiple pollutants and forest decline. ambio, 15:258-265. hinrichsen, d., 1987. the forest decline enigma. bio science.. 37:452-546. holmes, c.h., 1956. the natural regeneration of the wet and dry evergreen forests of ceylon. ceylon forester, 2:151-164. jacobi, j.d., 1983. metrosideros dieback in hawai'i: a comparison of adjacent dieback and non-dieback rain forest stands. new zealand journal of ecology, 6:79-97. johnson, a. h., mclaughlin, s. b., 1986. the nature and timing of the deterioration of red spruce in the northern appalachian mountains. national academy science report, acid deposition: long-term trends, national academy press, washington dc., pp. 200-230. gunarathne & perera /journal of tropical forestry and environment vol 4, no 01 (2014) 14-27 26 kandler, o., innes, j.l., 1995. air pollution and forest decline in central europe. environmental pollution, 90:171-180. laurance, w.f., williamson, b.g., delamonica, p., oliveira, a.a., lovejoy, t.e., gascon, c., pohl, l., 2001. effects of a strong drought on amazonian forest fragments and edges. journal of tropical ecology, 17:771–785. mader, d.l., thompson, b.w., 1969. foliar and soil nutrients in relation to sugar maple decline. proceedings of soil science society of america, 33:794-800. mclaughlin, d., gizyn, w., mcilveen, w., kinch, c., 1992. a quantitative tree crown rating system for deciduous forest health surveys: some results for ontario, in: manion, p.d., lachance, d. (eds.), forest decline concepts. aps press, st. paul, minnesota, usa, pp.137-154. mueller-dombois, d. (1980). the 'ohi'a dieback phenomenon in the hawaiian rain forest, in: john cairns, jr. (eds.), the recovery process in damaged ecosystems. ann arbor science publishers, inc., pp.153-161. mueller-dombois, d., 1986. perspectives for an etiology of stand level dieback. annual review of ecology and systematics, 17:221-243. mueller-dombois, d., 1990. forest decline and soil nutritional problems in pacific areas. water, air & soil pollution, 54:195-207. mwangi, e., swallow, b., 2005. invasion of prosopis juliflora and local livelihood: case study from the lake baringo area of kenya. world agroforestry centre, nairobi, kenya. ogden, j., 1970. plant population structure and productivity. proceedings of the new zealand ecological society, 17:1-9. papp, r.p., kliejunas, j.t., smith, r.s.jr., scharpf, r.f., 1979. association of plagithmysus bilineatus (coleoptera: cerambycidae) and phytophthora cinnamomi with the decline of ‘ōhi’ a-lehua forests on the island of hawaii. forest science, 25:187-196. pasiecznik, n.h., felker, p., harris, p.j.c., harsh, l.n., cruz, g., tewari, j.c., cadoret, k., maldonado, l.j., 2001. the prosopis juliflora-prosopis pallida complex. hdra. coventry, uk. perera, g.a.d., 2007a. forest die-back in bundala national park. protected area management and wildlife conservation project, department of wildlife conservation, sri lanka. perera, g.a.d., 2007b. role of seeds in the regeneration of tropical semi-deciduous forests of sri lanka abstracts of the eco summit 2007: challenges and opportunities for the 21 st century’s ecology. beijing, china. perera, g.a.d., 2012. preset status of dry-zone flora in sri lanka, in: weerakoon, d.k., wijesundara, s. (eds.), the national red list of sri lanka: conservation status of the fauna and flora. ministry of environment, colombo, sri lanka, pp.165-174. perera, g.a.d., suranjith, g.a.n., gunarathne, r.m.u.k., 2009. allelopathic effect of prosopis juliflora (sw) dc and its impact on some sri lankan dry forest species, national symposium on invasive alien species, negombo, sri lanka. pitelka, l.f., raynal, d.j., 1989. forest decline and acidic deposition. ecology, 70:2-10. piyankarage, s.c., mallawatantri, a.p., matsuno, y., pathiratne, k.a.s., 2004. human impacts and the status of water quality in the bundala ramsar wetland lagoon system in southern sri lanka. wetlands ecology & management, 12:473-482. prinz, b., 1985. prepared discussion. environmental science and technology, 35:913-915. raven, p.h., evert, r.f., eichhorn, s.e., 2005. biology of plants, 7 th ed. freeman. new york, usa. redmond, d.r., 1955. studies in forest pathology xv. rootlets, mycorrhiza, and soil temperatures in relation to birch dieback. canadian journal of botany, 33:595-627. gunarathne & perera /journal of tropical forestry and environment vol 4, no 01 (2014) 14-27 27 rice, k.j., matzner, s.l., byer, w., brown, j.r., 2004. patterns of tree dieback in queensland, australia: the importance of drought stress and the role of resistance to cavitation. oecologia, 139:190-198. rutnum, p.w., 1959. growth of plants under the natural forest of dry zone. ceylon forester, 4:224. sankaran, k.v., bridge, p.d., gokulapalan, c., 2005. ganoderma disease on perennial crops in india-an ovaeview. mycopathologia, 159:143-152. schulze, e.d., 1989. air pollution and forest decline in spruce (picea abies) forest. science, 244:776-783. smith, w.h. 1981. air pollution and forests. springer-verlag, new york. suresh, h.s., dattaraja, h.s., sukumar, r., 2010. relationship between annual rainfall and tree mortality in a tropical dry forest: results of a 19 year study at mudumalai, southern india. forest ecology & management, 259:762-769. turner, j., lambert, m., 2005. soil and nutrient processes related to eucalyptus forest dieback. australian forestry, 68:251-256. ulrich, b., 1983. soil acidity and its relations to acid deposition, in: ulrich, b., pankrath. j. (eds.), effects of accumulation of air pollutants in forest ecosystems. d. reidel publishing company, boston, massachusetts, u.s.a., pp.127-146. ulrich, b., mayer, r., khanna, t.k., 1980. chemical changes due to acid precipitation in a loess-derived soil in central europe. soil science, 130:193-199. vogelmann, h.w., badger, j.d., bliss, m., klein, r.m., 1985. forest decline on camels hump, vermont. bulletin of the torrey botanical club, 112:274-287. vries, w.d., kalp, j.m., erisman, j.w., 2000. effects of environmental stress on forest crown condition in europe. part i: hypotheses and approach to the study. water, air and soil pollution, 119:317-333. whitmore, t. c., sayer, j.a., 1992. tropical deforestation and species extinction. chapman and hall, london. wijesinghe, l.c.a., 1959. a study of girth increment of manilkara hexandra dubard (palu). ceylon forester, 4:219-224. wood, a., stedman-edwards, p., mang, j., 2000. the root causes of biodiversity loss. world wildlife fund and earthscan publications ltd., u.k. microsoft word 3 rice veewil fernando & karunaratne /journal of tropical forestry and environment vol. 2, no. 01 (2012) 20-25 20 ethnobotanicals for storage insect pest management: effect of powdered leaves of olaxzeylanica in suppressing infestations of rice weevil sitophilusoryzae (l.) (coleoptera: curculionidae) h. s. d. fernando 1* and m. m. s. c. karunaratne 2 1 *department of zoology, university of sri jayewardenepura, sri lanka date received: 10-10-2011 date accepted: 12-02-1012 abstract the rice weevil, sitophilus oryzae is one of the major pests of stored rice in sri lanka. this study investigates the effectiveness of the botanical olax zeylanica in controlling infestations of the rice weevil.in two separate bioassays, contact/feeding and fumigant toxicity of powdered leaves of o. zeylanica were tested against 1-7 days old adult s. oryzae under laboratory conditions. contact/feeding toxicity was tested by directly exposing adult weevils to 1.0, 3.0, 5.0 and 7.5g of leaf powder mixed with 100g of rice grains while fumigant toxicity was evaluated by using the same doses where theadults were exposed to fumes emitted from the leaf powders. in both bioassays 100% mortality of the adult s. oryzae was observed within 18 hours of exposure to 3.0, 5.0 and 7.5g doses of leaf powder. percentage adult weevil mortality in treated rice tested with three doses of o. zeylanica leaf powder at all the time intervals (except for 1.0g) was significantly higher (p < 0.05) than that of the corresponding control. no contact/feeding toxicity was recorded when adult weevils were directly exposed to 1.0g leaf powder whereas only 14% adult weevil mortality was observed even after 24hours of exposure to fumes ofleafpowder. results also revealed that mortality increased both with increasing dose and time of exposure. in both bioassays a 100% adult weevil mortality was obtained after18 hours of exposure to 3.0g leaf powder of o. zeylanica or to its fumes.moreover, ld50 values of 2.55g and 2.08g for leaf powders obtained after 12 hours of exposure to adult s. oryzae in contact/feeding toxicity test and fumigation test respectively.the results indicatedthat leaf powder of o. zeylanica is more toxic to adults s. oryzae when they were in direct contact with it.findings of this study bears out the exceptionally high efficacy of o. zeylanica leaves applied directly mixed with the rice grains or introduced as a fumigant to suppress weevil infestations in stored grains and strengthen the possibility of using powdered leaves of o. zeylanica as an alternative to synthetic chemicals in storage insect pest management. keywords: olax zeylanica, sitophilus oryzae, feeding toxicity, direct fumigation toxicity 1. introduction the utilization of plants with insecticidal properties to protect stored commodities against insect pest attack has a very long history (belmain and stevenson, 2001). leaves, bark, roots, twigs and flowers locally available plantsmixed with various stored products have been used for major insect pests *correspondence: sacdinu@gmail.com tel: +94 11 2804515 issn 2235-9370 print / issn 2235-9362 online ©2012 university of sri jayewardenepura fernando & karunaratne /journal of tropical forestry and environment vol. 2, no. 01 (2012) 20-25 21 of stored products as protectants in different parts of the world for centuries (hassanali and lwande, 1989; isman, 2006). the efficient control as well as removal of insect pests from stored food has long been the goal of many entomologists throughout the world. scientific literature documenting bioactivity of plant materials to insect pests shows, that a great number of plant species from a wide range of families have been assessed for their toxic, antifeedant and repellant properties (isman, 2006; talukder, 2006; dubey et al., 2008; ogunleye et al., 2010). many of the plant species that have been investigated are often those used as culinary spices or in traditional medicine by local communities (lale, 1992). some researchers surmise that these plant materials are therefore safe to use as insecticides. many researchers are trying to validate the efficacy of ethnobotanicals which are readily available in the local environment for farmer use at village level (ahmed and koppel, 1985) botanical insecticides have long been touted as attractive alternatives to synthetic chemical insecticides for pest management because botanicals reputedly pose little threat to the environment or to human health (isman, 2006). however, apart from localized use of traditional plant materials and isolation of a number of phytochemicals with insecticidal properties only a handful of botanicals such as pyrethrum, rotenone and neem are in widespread use (dev and koul, 1997; isman, 1997). the increasing attempts to replace synthetic insecticides with less expensive and locally available pest control means have been undertaken especially in the tropics (jermy, 1990). in the context of agricultural pest management, botanical insecticides can play a much greater role in the production and postharvest protection of food in developing countries (isman, 2006) who have the best supplies of the natural resource and have the most to gain from the development and local use of simple plant extracts for crop protection (koul and dhaliwal, 2001). in many countries, plant tissues or crude products of the plants, such as aqueous or organic solvent extracts, are used directly as protectants of stored products. these practices are labour intensive, but are often economically and ecologically sound, and do not require sophisticated technology (talukder, 2006). considering these facts, the present investigation was aimed at evaluating the toxic properties of powdered leaves of a local medicinal plant olax zeylanica (malla) belonging to the family olacaeceae against sitophilis oryzae, one of the major storage insect pests of worldwide distribution. 2. materials and methods 2.1 insect cultures parent stock of s. oryzaewas obtained from infested raw white rice bought from the local market. laboratory cultures of s. oryzaewere maintained on uninfected white raw (sudukekulu) rice. 25 pairs of adult rice weevils were introduced into plastic jars containing 400g of rice. these plastic jars were then covered with a muslin cloth to prevent insects escaping and to allow ventilation. after two weeks the adults were removed and the rice medium was kept in ambient laboratory conditions (30 ± 1 0 c and relative humidity of 85 ± 1 %) for the emergence of s. oryzae adults. for all the experiments 1-7 days old, unsexed adult weevils were selected from ongoing cultures.all the experiments were carried out under ambient laboratory conditions. 2.2 plant material fresh, mature leaves of o. zeylanica were used for all the experiments. these were washed, airdried and ground to a fine powder using a domestic electric grinder (multinational, 2101, india). leaf powders obtained in this manner was used for all experiments. 2.3 contact/feeding toxicity test powdered leaves of o. zeylanica, weighing 1.0, 3.0, 5.0 and 7.0g, were mixed with 100g of white raw rice (sudukekulu) in separate plastic containers (height 8cm, diameter 5cm) using a glass rod. thirty adult s. oryzaeweevils were then introduced into each container and the mouth of the container fernando & karunaratne /journal of tropical forestry and environment vol. 2, no. 01 (2012) 20-25 22 was covered with a muslin cloth. in the control, 30 adult insects were introduced into 100g of untreated rice. the number of dead adult weevils in each container was recorded after 6, 12, 18, 24 hours after their introduction. this experiment was replicated 5 times. 2.4 fumigation toxicity test the bio-apparatus for the direct fumigation toxicity test consisted of a plastic cup (height 8cm) inserted into a plastic container (height 12cm, diameter 8cm). required doses (1.0, 3.0, 5.0 and 7.0g) of freshly ground plant leaves were placed on the bottom of this container. the bottom of the plastic cup was cut off and replaced with a muslin cloth so that fumes emitting from leaf powder would reach the insects above. after the plastic cup was inserted into the container, 30 adult weevils were introduced into it and the top was covered with a polythene film. a similar bioassay set up without any plant material was considered as the control. observations on the adult weevil mortality were recorded after 6, 12, 18, 24 hours after the introduction of insects. five replicates were made in this experiment. 2.5 data analysis the means of mortality of each dose were compared using one-way analysis of variance (anova) and tukey’s pairwise comparison test. ld50 and ld99 values were determined by probit analysis. for all statistical calculations, miniatb 14 was used. 3. results and discussion contact/feeding toxicity of different doses of o. zeylanica leaf powder on s. oryzae at different time intervals are shown in table1. according to the observations, all the doses of leaf powder except the lowest dose (1.0g) showed significantly very high insecticidal effect on s. oryzae adults. in fact, adult mortality varied with dose and exposure periods indicating the mortality effect of the leaf powder treatments were dose and time dependent. however, it was evident that 1.0g of leaf powder was not effective even after 24 hours of exposure exhibiting only 3% adult mortality.moreover, 0% adultmortality was observed within 18 hours of exposure to both 1.0g of leaf powder and the control. all thethree other doses 3.0g, 5.0g and 7.0g of leaf powders exhibited 100% adult weevil mortality within 18 hours of exposure period to treatments. table1: direct contact/feeding toxicity effect of different doses of o. zeylanica leaf powder on s. oryzae dose (g) percentage mortality 6 hat 12 hat 18 hat 24 hat control 0.00 ± 0.00 a 0.00 ± 0.00 a 0.00 ± 0.00 a 0.00 ± 0.00 a 1.0 0.00 ± 0.00 a 0.00 ± 0.00 a 0.00 ± 0.00 a 3.33 ± 3.33 a 3.0 22.00 ± 3.80 b 69.33 ± 4.34 b 100.00 ± 0.00 b 100.00 ± 0.00 b 5.0 71.33 ± 7.30 c 96.67 ± 4.08 c 100.00 ± 0.00 b 100.00 ± 0.00 b 7.0 87.33 ± 6.41 d 99.33 ± 1.49 c 100.00 ± 0.00 b 100.00 ± 0.00 b probability p < 0.05 p < 0.05 p < 0.05 p < 0.05 means followed by the same letters in each column are not significantly different according to tukey’s test at p > 0.005 significance level. mean percentage mortality± sd for five replicates (n = 150) hat – hours aftertreatment the analyzed results of the present study indicated a similar dose and time dependent pattern of mortality when adult s. oryzae weevils were directly exposed to fumes of o. zeylanica leaf powder (table2). furthermore, results of this bioassay showed that fumigation toxic effect produced by the powdered leaves was higher than that of the contact or/and feeding toxicity effect it elicited. moreover, fernando & karunaratne /journal of tropical forestry and environment vol. 2, no. 01 (2012) 20-25 23 even 3.0g of leaf powder produced weevil mortality as high as 91% when they were exposed to the leaf fumes for 12 hours. on the other hand, only 69% mortality was noted for the same dose and exposure period, when the leaf powder was mixed with the rice medium (table1). however, with the higher doses (5.0 and 7.0) 100% adult weevil mortality was observed after 18 hours in both types of bio-assays. the extremely high weevil mortality seen in the fumigation bio-assay suggests that some volatile substance/s emanating from the powdered leaves may have a lethal effect on s. oryzae weevils. furthermore, the strong repulsive odour detected from o. ceylanica leaves when ground to powder indicates the release of some volatile substance/s. table 2: direct fumigation toxicity effect of different doses of o. zeylanica leaf powder on s. oryzae means followed by the same letters in each columns are not significantly different according to tukey’s test at p>0.005 * * mean percentage mortality± sd for five replicates (n= 150) * hat – hours aftertreatment the probit mortality lines for leaf powder for both contact/feeding and fumigation toxicity tests were analyzed at 6 and 12 hours after the treatment. values of ld50 and ld99 and their respective 95% fiducial confidence limits for both contact/feeding toxicity as well as fumigation toxicity are presented in table 3. table 3: probit analysis for contact and fumigation toxicities of o. zeylanica leaf powder on adult s. oryzae after 6 and 12hrs of exposure time *ld 50 value (g) **ld 99 value (g) fumigant contact fumigant contact 6 hat 5.95 (5.68-6.23) 4.16 (3.84-4.48) 10.29 (9.17-12.36) 12.21 (10.24-15.78) 12 hat 2.08 (1.84-2.29) 2.55 (2.28-2.78) 4.31 (3.83-5.07) 6.04 (5.29-7.33) *ld 50 – lethal dosage that kills 50 % of the weevil population **ld 99 – lethal dosage that kills 99 % of the weevil population 95% lower and upper fiducial limits are shown in parenthesis hat – hours after treatment based on this analysis it can be clearly stated that ld 50 value of fumigation toxicity exceeds the corresponding value of contact toxicity only at 6 hrs. after treatment but in all the other instances, the dose required to attain 50% weevil mortality was lower in the fumigation test than it was in the contact toxicity test. also, the lowest ld50 values of 2.55g and 2.08g for leaf powders were obtained after 12 hours of exposure to insects in contact/feeding toxicity test and fumigation test respectively. when these results are taken into consideration, it is quite apparent that o. zeylanica leaves could be to some extent more effective when used as a fumigant for the control of rice weevil. however, dose (g) percentage mortality 6 hat 9 hat 12hat 18 hat 24 hat control 0.00 ± 0.00 a 0.00 ± 0.00 a 0.00 ± 0.00 a 0.00 ±0.00 a 0.00 ±0.00 a 1.0 0.00 ± 0.00 a 0.00 ± 0.00 a 0.00 ± 0.00 a 1.67 ± 2.79 a 12.23 ± 7.79 a 3.0 0.00 ± 0.00 a 28.33 ± 6.91 b 91.67 ±3.50 b 100.00 ± 0.00 b 100.00 ± 0.00 b 5.0 24.43±14.56 b 88.90 ± 8.07 c 97.78 ±2.72 c 100.00 ± 0.00 b 100.00 ± 0.00 b 7.0 73.33 ± 5.96 c 97.23 ± 2.51 d 100.00 ± 0.00 c 100.00 ± 0.00 b 100.00 ± 0.00 b probability p < 0.05 p < 0.05 p < 0.05 p < 0.05 p < 0.05 fernando & karunaratne /journal of tropical forestry and environment vol. 2, no. 01 (2012) 20-25 24 the contact toxicity of o. zeylanica leaves on s. oryzaeweevils is also nearly as high as fumigation toxicity. therefore, the ability of this plant material to produce lethal effects against s. oryzae within a time period as short as 12-18hrs after treatment can be attributed to both fumigant and contact or/and feeding toxic properties of the leaf powder on s. oryzae. powders of various plant species with insecticidal activity have been used previously by several researchers in laboratory trials for the control of stored product pests including s. oryzae (niber, 1994; haq et al., 2005; akob and ewete, 2007; law-ogbomo and enobakhare, 2007). large variation in the sensitivity of stored grain pests to fumigation toxicity of volatiles of many plants have also been reported by several workers (lee et al.,2001; schmidt et al.,1991; shaaya et al.,1997; tripathi et al., 2002). plants belonging to the genus olax reportedly have antimicrobial and anti-inflammatory properties (ayandele and adebiyi, 2007). in traditional sri lankan medicine, leaves of o. zeylanicaare used to treat many ailments such as hypercholesterolemia (ediriweera et al., 2010) and snake bites. as olax zeylanica is also a plant material consumed by sri lankans this would be ideal to use it as a grain protectant against rice weevil infestations. the insecticidal activity of botanicals may possibly be dependent on different factors such as the presence of bioactive chemicals with diverse activities. the powdered leaves of o. zeylanica tested may act as a fumigant and a stomach poison. also the powder may act as a physical barrier blocking the spiracles of the insects thus impairing respiration leading to their death (law-ogbomo and enobakhare, 2007; mulungu et al., 2007). 4. conclusion the extremely high fumigation activity observed in the present study shows that insecticidal properties of leaves of o. zeylanica could be a source of some biologically active volatile compound/s that is potentially an efficient insecticide. consequently, the possibility of utilizing this natural fumigant to control stored product insectpests is worthy of further investigations. moreover, sri lankan farmers who are aware of the importance ofnonchemical based eco-friendly control methods would certainlyprefer to use such ethno-botanicals as stored product protectants. references ahmed, s. and koppel, b. 1985. plant extracts for pest control: village level processing and use by limited resource farmers. amer. assocadvanem. sci., 26-31. akob, c. a. and ewete, f. k. 2007. the efficacy of ashes of four locally used plant materials against sitophiluszeamais (coleoptera: curculionidae) in cameroon. international journal of tropical insect science. 27(1), 21–26. ayandele, a. a. and adebiyi, a. o. 2007. the phytochemical analysis and antimicrobial screening of extracts of olaxsubscorpioidea. african journal of biotechnology. 6(7), 868-870. belmain s, and stevenson p. 2001. ethno-botanicals in ghana: reviving and modernizing age-old farmer practice. pestic.outlook 12:233–38 dev, s. and koul, o. 1997. insecticides of natural origin, harwood academic publishers, the netherlands. pp. 365. dubey, n. k., srivastava, b., and kumar, a. 2008. current status of plant products as botanical pesticides in storage pest management. journal of biopesticides, 1(2):182 186 ediriweera e.r.h.s.s., ranbanda, k. m., and wellihinda, j. 2010. a clinical trial of the efficacy of kalashaka yoga in medovruddhi (hypercholesterolemia) ayu-research journal, gujarat ayurved university india, id.no.2811 fernando & karunaratne /journal of tropical forestry and environment vol. 2, no. 01 (2012) 20-25 25 haq, t., usmani, n. f., and abbas, t. 2005. screening of plant leaves as grain protectants against tribolium castaneum during storage. pakistan journal of botany, 37(1), 149-153. hassanali, a. and lwande, w. 1989. antipest secondary metabolites from african plants. in: j. t. arnason, b. j. r. philogene and p. morand (eds). pp. 78-94. insecticides of plant origin. acs symposium series no.387, u.s.a. isman, m.b. 2006. botanical insecticides, deterrents, and repellents in modern agriculture and an increasingly regulated world. ann.rev.entomol. 51:45–66. isman, m.b. 1997. neemasal and other botanical insecticides: barriers to commercialization. phytoparasitica, 25:339–344. jermy, t. 1990. prospects of the antifeedant approach to pest control: a critical review. j. chem. ecol .16(11):3151-3166. koul, o. dhaliwal , g. s. 2001. phytochemical biopesticides. amsterdam: harwood acad. 223 pp. lale, n. e. s. 1992. a laboratory study of the comparative toxicity of products from three spices to the maize weevil. postharvest biology and technology, 2: 612-664. lawogbomo, k. e. and enobakhare, d. a. 2007. the use of leaf powders of ocimumgratissimum and vernoniaamygdalina for the management of sitophilusoryzae (lin.) in stored rice. journal of entomology, 4(3): 253-257. lee, b. h., choi, w. s., lee, s.e. and park, b.s. 2001. fumigant toxicity of essential oils and their constituent compounds towards the rice weevil, sitophilusoryzae (l.). crop prot., 20: 317-320. mulungu, l. s., lupenza, g., reuben, s. o. w. m. and misangu, r. n. 2007. evaluation of botanical products as stored grain protectant against maize weevil, sitophiluszeamais (l) on maize. journal of entomology, 4 (3):258-262 niber, t.b. 1994. the ability of powders and slurries from ten plant species to protect stored grain from attack by prostephanustruncatus(coleoptera:bostrichidae)and sitophilusoryzae l. (coleoptera:curculionidae) journal of stored product research, 30(4): 297-301. ogunleye, r. f,. ogunkoya, m. o. and abulude, f. o. 2010. effect of the seed oil of three botanicals, jatrophacurcas, helianthus annus and cocosnucifera on the maize weevil, sitophiluszeamais (mots) plant product research journal 14: 14 – 18. schmidt, g. h., risha, e. m., and el-nahal, a. k. m. 1991. reduction of progeny of some storedproduct coleoptera by vapour of acoruscalamus oil. j. stored prod. res. 27(2):121-128. shaaya, e., kostyukovysky, m., eilberg, j. and sukprakam, c. 1997. plant oils as fumigants and contact insecticides for the control of stored-product insects. j. stored prod. res.33:7-15. talukder, f. a. 2006. plant products as potential stored-product insect management agents a mini review. emir. j. agric. sci. 2006. 18 (1): 17-32 tripathi, a.k., prajapati, v., verma, n., bahl, j.r., bansal, r.p., khanuja ,s.p.s., and kumar, s. 2002. bioactivities of the leaf essential oil of curcuma longa on three species of stored product beetles. j. econs. entomol., 95: 183-189. chapter five: discussion subasinghe /journal of tropical forestry and environment vol. 4. no 02 (2014) 31-44 31 modelling total height of eucalyptus grandis hill ex maiden s.m.c.u.p. subasinghe * department of forestry and environmental science, university of sri jayewardenepura, nugegoda, sri lanka date received: 17-01-2014 date accepted: 07-09-2014 abstract eucalyptus grandis hill ex maiden (rose gum) is an introduced species to sri lanka from australia. at present it has drawn attention of both public and private sectors due to the use as fuel, railway sleepers and sawn timber. this study focused on prediction of total height of e. grandis with age, which is an essential requirement in plantation management. data were collected from 26 even-aged plantations, covering all favourable regions of sri lanka for the growth of e. grandis. at first theoretical equations were formulated with four possible transformations. then parameters were estimated by fitting data at three different stages. r 2 values and standard residual distributions were used as preliminary evaluations. initially it was tried to model height using tree age as the only explanatory variable. both linear and exponential functions were used at this stage. the resultant models, however, were not successful for both functions due to low r 2 values. therefore next attempt was made after partitioning the data into different site types using a simple site index. three different site types were identified at this stage. then linear and exponential functions were separately fitted to each site type to estimate parameters for different site types while keeping the same basic equation forms. this attempt was also not successful due to low r 2 values, large outliers (for some site types) or incompatibility of the resultant models with biological reality. after the above unsuccessful attempts, the last step was conducted by pooling the data again and incorporating a second explanatory variable, site index. other than multiple linear functions, exponential and logistic functions were modified by adding the second explanatory variable at this stage. based on r 2 and standard residuals, seven suitable models were selected. then the estimated height values were fitted against an age series to test the distribution and compatibility with biological reality. finally, after both qualitative and quantitative evaluations, the best model was selected to predict the height growth for e. grandis in sri lanka for all site types. keywords: height model, eucalyptus grandis, site index, mathematical modelling 1. introduction modelling is especially important for species of widespread commercial use, both to understand growth and development of the species and to make better management decisions aimed at increasing productivity (fernandez and norero, 2006). moreover, accurate growth and yield predictions of trees and forests are important requirements for facilitating sustainable management of forest resources. * correspondence: upuls@sjp.ac.lk tel: +94 112804685 issn 2235-9370 print/issn 2235-9362 online © university of sri jayewardenepura 32 in commercial forestry, the important management decisions on different activities such as fertilising, thinning and harvesting are taken long before the trees achieve the required end dimensions. plantation age is therefore commonly considered as the first input parameter to predict the future values of important tree growth variables such as diameter, height, volume etc. it is therefore important to be able to make predictions of required tree variables from age, so that the change of growth with time can be readily determined. a second important input variable for yield prediction can be the quality of the site where the forests are grown. different sites support the tree growth in different manner, even for the same species. therefore it is common to include simple tree variables to represent the site quality (e.g., pienaar and harrison, 1989; soares et al., 1995) or site indices (clutter et al., 1992; vanclay, 1994), in the forest growth and yield models although the site classification can be done using many different methods (clutter et al., 1992). those simple variables or indices are frequently used in order to ease the measurement procedures and thereby to make the use of the constructed model is more practical. dominant height or top height are the most frequently used tree variables in this respect as these are considered to be independent of inter-tree competition (pienaar and harrison, 1989; clutter et al., 1992; soares et al., 1995). prediction of dbh and height is important in forestry since these two variables represent the horizontal and vertical growth of the stem respectively. height growth is an essential feature of most growth and yield models, which are a principal tool of forest management planning (boisvenue et al., 2004). the time required for a tree to reach a given height varies with its current growth rate, species, site quality, geographic location, site attribute and competition (carmean, 1975; oliver and larson, 1996). however, including all these factors in a growth model can be difficult due to difficulty of quantifying some of the parameters (e.g. competition) and due to the high cost of the required measurements. peterson and peterson (1994) found that most of the variation in height growth in harsh environments was due to species differentiation, with site and aspect as contributing factors. individual tree height growth partly changes the stand structure and in turn, stand structure is a determinant of individual tree height growth. modelling of height can therefore be used to reveal underlying factors. in forest growth modelling, it is common to find both construction of new mathematical equations (e.g. fontes et al., 2003; boisvenue et al., 2004; wang et al., 2005) as growth models or development of existing mathematical equations further to achieve more realistic predictions. among the already available mathematical functions which have been used to develop growth or yield models in the past, lundqvist-korf (1939), schumacher (1939), bertalanffy (1957) and richards (1959) functions are most common (e.g. palahi et al., 2004; sanchez-gonzales et al., 2005; salas and garcia, 2006; rammig et al., 2007; adame et al., 2008). the new models were mostly constructed by using assumptions on the relationships between the response variable and the explanatory variables. in latter stages of model building those relationships were mathematically tested to obtain the statistical parameters which determine the magnitude and the direction of the relationships. in 1994, niklas stated that simple linear relationships were appropriate for tree growth prediction. however, according to fernadez and norero (2006), more complex formulae can be utilised to describe morphological association of variables. this change in approach may result from the subasinghe /journal of tropical forestry and environment vol. 4. no 02 (2014) 31-44 33 increased availability of affordable computing and the development of easier to use statistical packages. however, it is important that the selected candidate variables for modelling should represent the basic biological processes of tree growth (boisvenue et al., 2004). 2. methodology 2.1 details of the plantations selected rose gum (eucalyptus grandis hill ex maiden) was selected for the current study since it plays a major role in plantation forestry in sri lanka. it is mostly managed as even-aged monocultures in the country in the areas of upcountry wet zone. in order to represent the areas where the selected species is mainly grown, 26 plantations were selected from badulla, bogawantalawa, haputale, kandapola, kandy, maskeliya, nuwara eliya and pattipola regions. the age of those plantations varied from 9 to 45 years. 2.2 sampling and data collection although even-aged monoculture plantations were selected for the present study, stratified random sampling was employed for data collection in order to have a better representation for the entire plantation. stratification was visually done by observing geographical variations at each site. at least two samples of 0.02 ha were selected in each stratum. 2.3 construction of model structures since height generally increases with age, it was decided to use age as the primary explanatory variable. although it was initially assumed that the growth of height can be predicted primarily as a function of age, it was accepted that site quality and degree of inter-tree competition can both also have a major effect on tree growth rates. with considering the above factors, the constructed basic model structure is given in equation 1. height = f (age, site quality, competition) 1 similar model structures were used by subasinghe (1998) and lee et al., (2004) for constructing mathematical models in forestry. lee et al., (2004), however, tried to eliminate the age from the selected explanatory variables, but found out that modelling performance decreased if fitted without age. at the first stage, and in order to construct a simple model, it was decided to model height separately using age as the only explanatory variable. the use of other explanatory variables especially site quality was considered only if this exercise failed. competition was eliminated as an explanatory variable since the tree’s own growth parameters already reflected the competition experienced. 2.4 identification of the relationships between selected variables according to many growth modellers (soares et al., 1995; vanclay, 2004; wang et al., 2005), the best way to reveal the relationships between explanatory and response variables is to study the scatter distribution. following their work, it was decided to observe the scatter distributions between selected variables in order to identify the pattern of relationships (i.e., whether linear or non-linear) of height with age and thereby to identify the sign associated with statistical parameters. 34 2.5 data partition due to growth differences in order to partition data, the scatter distribution of height with age was both carefully examined. moreover, the distribution of top height with age was tested since top height is believed to be a good indicator of site quality since it is independent from the competition (clutter et al., 1992; philip, 1994). in order to combine the above qualitative results with a quantitative value, a site index function was developed using top height and age (equation 2). ahsi top / 2 where: a = plantation age, yr htop = top height, m si = site index 2.6 stages of model construction the entire modelling exercise conducted in this study can be divided into three stages. in order to build a less complex model, it was decided to construct a simple model to predict height using age as the only explanatory variable at the first stage. moreover, it was decided to construct a common model without partitioning the data by site or growth differences. the reason for this latter approach was to eliminate the complexity of using different models to predict the same variable for different site types. if the models constructed at the first stage indicated bias, the next stage of the present study was to model height separately for the partitioned data by growth differences. after partitioning data according to different growth patterns, the next step was to fit the same model structure (linear or nonlinear) separately to different data sets to obtain different sets of statistical parameters. in order to simplify the constructed models, it was decided to first use simple linear models and then to compare these with exponential and logistic functions. if the attempts on both stage one and two were failed, the next possible option was to include an additional explanatory variable to represent the quality of site without partitioning data. for this reason, the age was selected as the first (primary) explanatory variable and in addition to that, a second variable, i.e., site quality, was decided to use. second explanatory variable (site quality) the second variable, site quality, was used in two ways; as quantitative and partially qualitative variables. as a quantitative value for the site index, it was decided to use top height/plantation age (equation 2). when the mean top height/age for each plantation was observed, it was possible to identify three distinctive sets of values and thereby three different site classes. then a new site index was developed accordingly for each class (see table 1) by assigning a qualitative value (column 4 of table 1) which is approximately similar to the average top height/age (column 3) value for each class. this value was deliberately reduced to 0.5 for the class iii in order to keep a constant interval between the new si values. for the other two classes, the new si values were similar to the calculated average values in the column 3. finally each class is given a description as good, average or poor classes. table 1:newly assigned site classes for different site types. class (1) growth rate (2) average si (3) new si (4) description (4) plantations (5) i ii iii high average poor 2.4 1.6 1.1 2.5 1.5 0.5 good average poor 4 18 4 subasinghe /journal of tropical forestry and environment vol. 4. no 02 (2014) 31-44 35 it was decided to add the second explanatory variable (si) to the model in two ways, i.e., as an additive (equation 3) and multiplicative variable (equation 4). for each situation described in equations 3 and 4, the combination of the si and associated statistical parameter was included in three ways, i.e., (i) parameter × si; (ii) parameter si ; and (iii) si parameter . h = f age (as explanatory or logistic) + (top height/age or si) 3 h = f age (as explanatory or logistic) × (top height/age or si) 4 age was included in exponential or logistic form into the models. it was therefore not transformed into any other form. however, si (both top height/age and new si) was transformed into four biologically acceptable forms, i.e., natural logarithmic, square, square root and reciprocal. 2.7 fitting models structures to data fitting the selected non-linear models to data was done using spss statistical software. the major forms of the models are given in the equations 5 and 6 (as explanatory models) and 07 and 08 (as logistic models) without transformation of the si variable. sibbbh age 321  5 sibbbh age 321 * 6 siccagecch 4321 )))(exp(1/(  7 siccagecch 4321 )))(exp(1/(  8 2.8 model evaluation the quality of the resultant modes were primarily examined using r 2 and distribution of residuals. for the selected models by above two tests, three quantitative measurements, i.e., average model bias, mean absolute difference and modelling efficiency were calculated to evaluate the chosen models further. the latter tests have proved adequate for model evaluation by many authors in the past (fontes et al., 2003; hein et al., 2007; rammig et al., 2007; rodriguez et al., 2003; soares et al., 1995). 2.9 validation of the finally selected models this step was done to identify the most suitable models to be used in the field. the dbh and height values were predicted using ages from year 5 to 50 at five-year intervals separately for three classes. for the models which contain top height /age as the second explanatory variable, the average values calculated at the model construction phase were used for each class (i.e., 2.4, 1.6 and 1.1 – table 1). for the models which contain si values 2.5, 1.5, 0.5 were respectively used for class i, ii and iii (table 1) as the second explanatory variable. 3. results 3.1 stage one: construction of simple common models using age as the only explanatory variable the simple linear model (equation 9) resultant at this stage was given in equation 9. r 2 of that model was 50.0% and the intercept was significant which could not biologically be explained without specifying a range of validity using age. 36 h = 17.7 + 0.665  age 9 transforming variables into other forms did not improve the quality of r 2 or residual distribution due to these reasons, the above model was therefore discarded. in order to be compatible with growth rates slowing with age, it was decided to use exponential relationships to predict height from age under the stage one. when the exponential function was fitted, the resultant r 2 value was low due to the high leverage of some data points. it was therefore decided to observe the improvement of the models after removing the datum which had the highest leverage. even the new model (equation 10), had low r 2 value (56.1%). the fitted line plot for the equation 9 is given in the figure 1. )9548.0(1.478.51 age h  10 figure 1: fitted exponential models with observed data for height after removing datum with the highest leverage. in addition to that, there was an over-estimation by the resultant model (equation 10) in the early years of age according to the fitted model (figure 1). the logistic model built behaved in the same manner and therefore the stage one was not successful for the present study. 3.2 stage two: modelling with partitioned data in order to partition the data by the growth differences as described in the methodology, scatter distribution between height and age was observed (figure 2). according to that figure, the distribution of height with age indicated three separate clusters. the majority of data were located at the middle and four plantations were located above (kp 1,43; pp 1,85; po 4,11 and po 2,16) and four plantations were located below (bk 2,10; bk 2,24; pp 1,08 and ht 2,08) the major cluster. these variations were identical for both dbh and height and therefore it was concluded that the growth of rose gum in measured plantations was being influenced by some other parameters in addition to the age. at this stage that factor was assumed as the site quality which was therefore used as the second explanatory variable in latter stages of model building. 0.0 15.0 30.0 45.0 60.0 0 10 20 30 40 50 age, yrobs_ht fit_ht ht, m subasinghe /journal of tropical forestry and environment vol. 4. no 02 (2014) 31-44 37 figure 2: distribution of height with age for all measured rose gum plantations. according to those results, the entire data set was divided into three classes as shown in the table 2. the average site index values calculated for different growth classes are also given in the same table. after partitioning data, the next step was to fit the same model structure (linear or non-linear) separately to the three sets of data to obtain the relevant statistical parameters. table 2: new categorisation of measured rose gum plantations according to partitioned data. class growth rate average si i ii iii high average poor 2.4 1.6 1.1 simple linear models the simple linear models constructed to predict the dbh and height using age and the associated r 2 values are given in table 3. table 3: resultant simple linear models for different site classes to predict height. class model r 2 % i 19.370 + 1.0340  age 2.005  age 1$ 93.9 03.6 ii 6.310 + 1.1043  age 1.348  age 1$ 90.2 85.3 iii 0.961  age 2$ 78.9 1$ intercept was significant, but forced through 0; 2$ intercept was not significant, but residual distribution became poor when re-fitted without intercept. 38 the intercept of the height prediction models were significant for the models built for classes i and ii. class iii was the only occasion where the intercept was not statistically significant. when forcing the intercept to zero for the other two classes, i.e., i and ii, the r 2 value dropped significantly especially for the class i (table 3) or the residual distribution became poor. therefore the linear models built for different growth classes were not successful for this study. prediction of height using age as an exponential function in order to eliminate the drawbacks of the linear models, it was decided to fit standard curves to predict height of rose gum plantations. as the first step, age was used as an exponential function without the asymptote. since class ii has a larger data set, those data were modelled first. the resultant model is given in equation 11. age h 032.1180.14  11 the estimated r 2 value for height model was 88.0% and the standard error was 4.12 m. the parameter associated with age was higher than 1.0 which showed an indefinite increase of height with age. this phenomenon cannot biologically be explained and therefore it was not decided to test the exponential equations for the next two classes. prediction height using age as a logistic function in order to construct better models to predict height, age was included as a logistic function without the asymptote. the resultant models and r 2 values are given in table 4. other than the height prediction model for class iii, the resultant r 2 values were approximately 90% or greater (table 4). however, the standard residual distribution for the models built for the growth class iii, it was poor. table 4: resultant logistic models for different site classes to predict height without the asymptote. class model r 2 i 43.93/(1+e(-0.193  (age-6.03))) 99.1 ii 63.60/(1+e(-0.076  (age-23.93))) 89.8 iii 50.50/(1+e(-0.142  (age-30.81))) 56.3 due to those reasons, the attempts made to build models using linear, exponential and logistic functions separately for different growth glasses to predict height was not successful at the stage one. 3.3 stage three: prediction of height using non-standard non-linear models due to the failures of stage one and two, non-standard non-linear models were selected in order to improve the model predictions by adding more than one explanatory variable as described in the methodology. after carefully studying the residual distributions and the results of quantitative evaluation, it was possible to select 7 models from height prediction models as given in table 5. priority was given for the high modelling efficiency values and the low mean absolute differences since these are quantitative values. only then were the normal residual distributions considered. subasinghe /journal of tropical forestry and environment vol. 4. no 02 (2014) 31-44 39 table 5: selected height prediction models for the validation. no model modelling efficiency mean absolute difference h1 h2 h3 h4 h5 h6 h7 (43.852/(1+exp(-0.117×(a-25.497)))+(7.590^(si^0.5)) (41.832/(1+exp(-0.128×(a-28.664)))+(11.098×si) $1 (47.474/(1+exp(-0.100×(a-20.930)))+(3.165^si) (32.005/(1+exp(-0.288×(a-18.773)))+(8.221×topa) (46.772/(1+exp(-0.114×(a-17.085)))×(0.908×(topa^0.5)) (11.240×1.032^a)×(1.112^(si^2)) (72.402/(1+exp(-0.051×(a-36.728)))×(1.107^(si^2)) 0.93 0.92 0.90 0.90 0.90 0.91 0.89 2.64 2.63 2.97 2.62 2.78 2.62 2.92 validation of the selected models distribution of predicted values of height of the models listed in table 5 with a series of age is given in figure 3. 3.4 final evaluation of the height prediction models when observing figure 3a, b and c, it was clear that the models h6 and h7 over-estimated the height values with age. both models were therefore removed from further study. model h4 indicated the complete stoppage of height growth after 25 years of age which is highly unlikely in sri lankan conditions. the model h4 was therefore eliminated from further study. when the residual distributions were examined, those were poor for the models h1 and h3. therefore those models were also eliminated. 3.5 the chosen models both the selected models (h5 and h2 in table 5) contained age expressed logistically and the difference is given by the type of the second explanatory variable and the way it was used in the models. these models are re-written as equations 12 and 13 (h5 and h2 respectively in the table 5) below and assigned the news numbers as models 1 and 2 respectively. model 1       agetopheightageh /908.0085.17114.0exp1/772.46  12 model 2       siageh  098.11664.28128.0exp1/832.41 13 for the first model (equation 12), the second explanatory variable was top height/age which entered into the equation as a multiplicative variable (equation 12). the second explanatory variable of the second model (equation 13) was si which was a partially qualitative value and it entered into the model in additive manner. the distributions of the predictions done by those two models separately for each site class are given in the figure 4. 40 figure 3: predicted height values against age for site class i (a), ii (b) and iii (c). 3.6 finally selected models to predict height when observing figure 4a, the differences in the shapes of the curves were clearly highlighted. for the model 1 (equation 12), the constructed curves tend to come together at lower ages which could biologically be well explained since, for trees growing on different sites, growth starts differentiating at a young age, not in very early stages. moreover, the growth predicted by the models slowed down after 30 years of age, which is very much compatible with the observed rose gum growth in sri lanka. figure 4b also shows evidence that the second model departed from biological reality. curves constructed for model 2 (equation 13) for height were parallel to each other in each case. at very low ages, i.e., 5 years, the growth differences were very high and equal for all three classes. this phenomenon would not occur in reality and therefore could not be explained biologically. a: class i 0.0 20.0 40.0 60.0 80.0 100.0 120.0 0 10 20 30 40 50 60 age, yr h t, m b: class ii 0.0 15.0 30.0 45.0 60.0 75.0 90.0 0 10 20 30 40 50 60 age, yr h t, m c: class iii 0.0 10.0 20.0 30.0 40.0 50.0 60.0 0 10 20 30 40 50 60 age, yr h t, m subasinghe /journal of tropical forestry and environment vol. 4. no 02 (2014) 31-44 41 figure 4: distribution of the predicted values with age for all site classes for the model 01 (a) and 02 (b) respectively. the reason for the different behaviour of the two different models (equations 12 and 13) was due to the way of entering the second explanatory variable to the model. in equation 12, this variable entered in multiplicative manner and therefore the growth rates were not parallel at different stages of the growth (figure 4a). however, the second variable entered into equation 13 in additive manner and therefore it maintained a parallel relationship for the growth of dbh and height in different site classes as shown in figure 4b. therefore, the second model was impossible to explain biologically and moreover, its predictions were unachievable at the early stages. therefore the model given in equation 12 was finally selected to predict the height for all the classes of rose gum plantations in sri lanka. the results of the validation of the finally selected model predictions with the raw data are given in figure 5. figure 5: final validation of the selected height model with selected raw data. a: model 01 0.0 20.0 40.0 60.0 80.0 0 10 20 30 40 50 60 age, yr h t, m class i class ii class iii b: model 02 0.0 20.0 40.0 60.0 80.0 0 10 20 30 40 50 60 age, yr h t, m class i class ii class iii model 01 0.0 20.0 40.0 60.0 80.0 0 20 40 60 age, yr h t, m raw ht class i class ii class iii 42 according to the results of the validation of the finally selected model, as given in figure 6, height values at age 30 (plantation id: bk 2,10) indicated a slightly lower value even for the site class iii. this could be due to very poor site quality in the region for rose gum growth. other than this particular age, the rest of the data were well covered with the selected models suggesting suitability for field use. 4 discussion one of the objectives of the present study was to construct the best models to predict height of rose gum growing as monocultures in sri lanka. for this purpose, all the possible combinations of selected candidate variables were tested with different transformations (altogether 60 different model structures were tested at stage three). for these combinations, exponential or logistic functions were modified using age and a site index as explanatory variables. lee et al., (2004) did a similar procedure and a range of models with exponential and power functions was evaluated, using a variety of combinations of independent variables. moreover, in their modelling process, calama et al., (2003) and adame et al., (2008) emphasised the importance of data chosen for fitting the different functions containing all the possible combinations of variables. fernandez and norero (2006) performed 45 linear regressions in modelling the growth of branches of individual trees in each site, management and type of branch. therefore it is not an uncommon exercise to test the different combinations of selected variables to in forest growth modelling. in addition to the untransformed variables, four simple transformations (logarithmic, square root, square and inverse) of the variables were used in this study on the assumption that those transformations can biologically be explained. however, complex transformations were sometimes used in forest growth modelling. as an example, boisvenue et al., (2004) used arcsine and cosine transformations of selected explanatory variables to model the height growth of small trees in mixed species stands in southern british columbia in canada. age has become one of the essential explanatory variables for tree growth prediction in forestry (e.g.: palahi et al., 2004; adame et al., 2006; salas and garcia, 2006). however, according to lee et al., (2004), although tree age is an important influencing variable on radial growth, it might simply be not available in practice. however, the attempts made by them to exclude the age from the explanatory variables to predict dbh growth of pine and oak were not successful and the resultant models indicated poor statistical performances. therefore they decided to include age in order to obtain better results. however, for the present study, age was included from the beginning of the model construction as an essential explanatory variable. this was done with the intention of predicting height and diameter along a series of an age. site index models have been constructed in the past (e.g., clutter et al., 1992; fontes et al., 2003; palahi et al., 2004; louw and scholes; 2006) mainly to classify the forest site types. moreover, site indices have been used as explanatory variables in some growth prediction models. pienaar and harrison (1989) and soares et al., (1995) used dominant height as a site representation variable to predict basal area and height respectively. however, a top height related index was selected for this study to represent the site quality since top height is known as independent from the competition (clutter et al., 1992; philip, 1994). since tree crown is responsible for the photosynthesis process, it was possible to use crown variables to indicate the competition among trees. however, these were not included as explanatory subasinghe /journal of tropical forestry and environment vol. 4. no 02 (2014) 31-44 43 variables in this study, because crown assessment in the field is expensive and time consuming. for the same reasons, lee et al., (2004) eliminated the crown parameters from model construction. a validation procedure was not followed at the model construction stage one and two of this study. the reason was the poor statistical qualities of the constructed models at those two stages. in addition to the qualitative tests, a combination of three quantitative tests, i.e., average model bias, mean absolute difference and modelling efficiency, were used for the model evaluation in this study. rodriguez et al., (2003) suggested that the mean squared error is another good indicator of the model quality. however, following the work of soares et al., (1995), hein et al., (2007) and rammig et al., (2007), the combination of the above three quantitative tests was used. in any modelling project, several aspects of the posed problem need to be reconciled with conceptual, mathematical, engineering and ecological aspects (huang et al., 2003). growth equations have a quite different character from standard equations; they are heuristic generalisations rather than applications of an underlying theory (huang et al., 2003). no single model will be best for all purposes and it is prudent not to expect otherwise. there are several reasons for this. first models are simplifications of reality and reflect the inherent inclinations, limitations, assumptions, biases and purposes of the modeller. secondly, models contain collective knowledge gained from previous experience along with current information. as such, models are dynamic and change as new knowledge and more relevant information become available (amateis, 2003). it is also known that increased complexity of a model reduces the generality of the considered model (radonja et al., 2003). references adame, a., hynynen, j., canellas, i. and del rio, m. 2008. individual-tree diameter growth model for rebollo oak (quercus pyrenaica willd.) coppices. for ecol. manage, 255: 1011–1022. amateis, r.l., 2003. quantitative tools and strategies for modelling forest systems at different scales. in a. amerao, d. reed and, p. soares (ed) modelling forest systems, cab international, uk bertalanffy, lv., 1957. quantitative laws in metabolism and growth. quart rev. biol., 32: 217-231. in rammig, a., bebi, p. bugmann, h and fahse, l., 2007. adapting a growth equation to model tree regeneration in mountain forests. eur. j. for. res., 126: 49-57. boisvenue, c., temesgen, h. and marshall, p., 2004. selecting a small tree height growth model for mixed species stands in the southern interior of british columbia, canada. for. ecol. & manage., 202: 301-312. burkhart, h.e. 2003. suggestions for choosing an appropriate level for modeling forest stands. in amerao, a., reed, d. and, soares, p. (ed) modelling forest systems, cab international, uk calama, r., cañadas, n. and montero, g. 2003. inter-regional variability in site index models for evenaged stands of stone pine (pinus pinea l.) in spain. ann. for. sci., 60: 259–269. carmean, w.h. 1975. forest site quality evaluation in the united states. adv. agron., 27: 209-267. clutter, j.l., fortson, j.c., pienaar, l.v., brister, g.h. and bailey, r.l. 1992. timber management: a quantitative approach. kreiger publishing co., florida. fernandez, m.p. and norero, a. 2006. relation between length and diameter of pinus radiata branches. scandinavian journal of forest research, 21: 124-129. fontes, l., tome, m., thompson, f., yeomans, a., luis, j.s. and savill, p. 2003. modelling the douglas-fir (pseudotsuga menziesii (mirb) franco) site index from site factors in portugal. forestry, 76: 491–507 hein, s., makinen, h., yue, c. and kohnle, u. 2007. modelling branch characteristics of norway spruce from wide spacings in germany. for ecol & managet, 242: 155–164 44 huang, s., yang, y. and wang, y. 2003. a critical look at procedures for validating growth and yield models. in a. amerao, d. reed and, p. soares (ed) modelling forest systems, cab international, uk lee, w.k., von gadow, k., chung, d.j., lee, j.l. and shin., m.y. 2004. dbh growth model for pinus densiflora and quercus variabilis mixed forests in central korea. ecol. model, 17: 187–200 louw, j.h. and scholes, m.c. 2006. site index functions using site descriptions for pinus patula plantations in south africa. for. ecol. & manage, 225: 94–103 lundqvist-korf, 1939 in palahi m., tome m., pukkala t., trasobares a. and montero g., site index model for pinus sylvestris in north-east spain, for. ecol. & manage, 187(2004): 35–47. niklas, k.j. 1994. plant allometry: the scaling of form and process. chicago, il: univ. of chicago press. oliver, c.d. and larson, b.c. 1996. forest stand dynamics, john wiley & sons, inc, new york palahi m., tome m., pukkala t., trasobares a. and montero g. 2004. site index model for pinus sylvestris in north-east spain, for. ecol. & manage, 187(2004): 35–47. peterson, d.w. and peterson, d.l. 1994. effect of climate on radial growth of subalpine conifer in the north cascade mountains. can. j. for. res., 24:1921–1932. philip, m.s. 1994. measuring trees and forests. 2nd ed. cab international, uk. phillips, p.d., brash, t.e., yasman, i., subagyo, p. and van gardingen, p.r. 2003. an individual-based spatially expicit tree growth model for forests in east kalimantan (indonesian borneo). eco. model, 159: 1– 26. pienaar, l.v. and harrison, w.m. 1989. simultaneous growth and yield prediction equations for pinus elliotti plantations in zululand. south african forestry journal, 149: 48-53. radonja, p.j., koprivica, m.j. and lavadinovic, v.s. 2003. modelling current annual height increment of young douglas-fir stands at different sites. in a. amerao, d. reed and, p. soares (ed) modelling forest systems, cab international, uk rammig, a., bebi, p. bugmann, h and fahse, l. 2007. adapting a growth equation to model tree regeneration in mountain forests. eur. j. for. res., 126: 49-57. richards, f.j. 1959. a flexible growth function for empirical use. j. exp. biol., 10: 290–300. rodriguez, f., de la rosa, j.a. and aunos, a. 2003. modelling the diameter at breast height growth of populus x euramericana plantations in spain. in a. amerao, d. reed and, p. soares (ed) modelling forest systems, cab international, uk salas, c. and garcia, o. 2006. modelling height development of mature nothofagus oblique. for. ecol & manage., 229: 1-6 sanchez-gonzales, m., tome, m and montero, g. 2005. modelling height and diameter growth of dominanat cork oak in spain. ann. for. sci., 62: 633–643. schumacher, f.x. 1939. a new growth curve and its application to timber yield studies. j. for., 37: 819-820. soares, p., tome, m., skovsgaard, j.p. and vanclay, j.k. 1995. evaluating a growth model for forest management using continuous forest inventory data. for. ecol. & manage, 71: 251-266. subasinghe, s.m.c.u.p. 1998. construction of growth models for pinus nigra var. maritime (ait) melville (corsican pine) in great britain. phd thesis, school of agricultural and forest sceinces, university of wales bangor, uk vanclay, j.k. 1994. modelling forest growth and yield: applications to mixed tropical forests. cab international, uk. wang, y., raulier, f. and ung, c.h. 2005. evaluation of spatial predictions of site index obtained by parametric and nonparametric methods: a case study of lodge pole pine productivity. for. ecol. & manage, 214: 201-211. microsoft word 4. kumara *correspondence: chamindakumara03@yahoo.com tel: +94714469539 issn 2235-9370 print/issn 2235-9362 online © university of sri jayewardenepura 36 challenges of biopiracy: implementing community based ecotourism (cbet) in the sri lankan context h.i.g.c. kumara deaprtment of geography, university of ruhuna, sri lanka date received: 16-09-2016 date accepted: 24-12-2016 abstract protecting the right of the local community/country to use their own genetic resources available in a particular area is an important element of environmental and biodiversity conservation. however, one of the biggest biodiversity conservation challenges faced by southern peripheral countries is biopiracy and related issues. community based ecotourism (cbet) is a well-established concept and its implementation is an important component in many regional development strategies. this research argues that though cbet which originated as a western concept has been successfully applied in number of projects, it generates biopiracy challenges in its implementation when cbet operates within different geo-political, economic and cultural contexts. this research examines such challenges to cbet initiatives in the sinharaja world heritage site, sri lanka. a qualitative-inductive research methodology has principally guided this research to examine the socio-cultural and socio-economic context of biopiracy issues. a total of 293 participants have informed this research including 193 interviews. a critical discourse analysis (cda) method is used to examine both primary qualitative data collected through participant and direct observation, interviews and secondary data. one of the main findings is that despite plans being developed at a community level, in wider context, challenges of biopiracy related to superimposed capitalism contest cbet ideologies. superimposed capitalism results in individualistic and competitive behaviours that undermine collaborative and responsible community approach. presently, smuggling out of wallapatta plant (gyrinops walla) and gathering of spotted bowfinger gecko (cyrtodactylus triedra) which is an endemic nocturnal reptile species have become profitable in kudawasinharaja site and a growing number of biopirates venture into here. local community of this site takes risks in forest genetic resources smuggling because it provides them with the means of earning much money within a short period. regardless of all prevalent laws and regulations against bioprospecting, biopiracy, biological resource and wildlife smuggling, authorities have still failed to control these activities in this site because of the support given to bio-pirates by the local community. the research concludes that cbet is an appropriate pathway for tourism development in sri lanka but recognition of biopiracy issues associated with superimposed capitalism is required and needed to be addressed. a well-defined monitoring system and an effective legal framework to control adverse effects are important for achieving cbet goals while confronting biopiracy. keywords: biopiracy, community based eco-tourism, superimposed capitalism. kumara. /journal of tropical forestry and environment vol. 6, no 02 (2016) 36-49 37 1. introduction most poor and developing countries of the world want to develop their economies as greater wealth, on the global stage, provides greater power. economic development, though, was long jeopardized by colonial relations which seem difficult to overcome, even today. different means of boosting economic growth have been tried, following different political outlooks. western development theories and discourses have heavily influenced the development process of southern peripheral countries based on two main reasons. first, the process of globalization has shrunk time and space barriers and western knowledge easily flows into developing world. second, geo-politically as well as economically southern peripheral countries depend heavily on the western world and it leads to core-peripheral dependency on western knowledge (clark, 2008). more recently, some countries have turned to tourism, which has become a global practice, as a possible boost to their foreign exchange income and to reduce poverty. domestic flows of tourists have also been encouraged to redistribute wealth within individual countries. however, here too, many southern peripheral countries have used western theories as the baseline in their tourism and ecotourism policies (chaperon & bramwell, 2013). for instance, sri lanka changed its top to bottom forest management approach and created a new forestry sector master plan in 1995, following the bottom up development and sustainable development ideologies to achieve forest management, to empower marginalized local communities and to seek theoretical and practical answers for contemporary forestry sector issues (vitarana & rakaganno, 1997). under this master plan, eco-tourism and cbet approaches were at the centre of attention of environmental policy makers and researchers of the country (dangal & de silva, 2010; kahveci, ok, & yýlmaz, 2011; ngece, 2011). ecotourism, in this article is defined as ‘environmental friendly responsible travel’ links to sustainable development. as well, cbet emphasizes ‘the roots or underling principles derived from concepts of community development a small scale locally oriented and holistic approach to economic growth and social change’ linked to the idea of spreading benefits to the whole community, or at least to the largest number as possible to help improve its economic outlook. critics, using post colonialism and sustainable development ideas have helped to build up the rationality of this approach (brydon, 2004; ziai, 2011). moreover, sri lanka is a developing island country in south asia, rich in extensive biodiversity owing to its geo-physical positioning in a tropical climate zone (lynam, jong, sheil, kusumanto, & evans, 2007). among the different types of eco-systems, tropical rain forests of sri lanka have become most attractive and biologically precious for their recorded high biodiversity and endemic species rates (brand, 2012). among all the rain forests of sri lanka, sinharaja is the biggest, consisting of 11,187 hectares spread over an elevation range of 1501150 m above sea level and first declared world natural heritage biological unit of sri lanka by unesco in 1988 (forest department, 2014). even if tea planting has become popular in these areas as a better income source, finding land for cultivation has become a major problem for the new generation. before the 1990s, farmers illegally cleared forestland for their cultivation needs, yet now the rules and regulation against forest clearance have been tightened. therefore, it has become very difficult for young people to clear forest areas for farming and they always clash with forest officers in their struggle 38 to find new land for cultivation needs (kumara, 2010). on the other hand, increasing human population and youth unemployment have become common in this area, the poverty rate has increased, so that the local community is economically marginal (forest department, 2013a). to meet these challenges, the government and the forest department together proposed implementing of cbet in this site. implementing cbet in the kudawa-sinharaja context seems ideologically rational, however, owing to many contextual challenges, project planners have failed to achieve its sustainability goals which are based on western ideological dimensions (forest department, 2013a). since biopiracy is one of the prominent issues among all these challenges, it is focused in this article. protecting the right of the local community/country to use their own genetic resources available in a particular area is an important element of environmental and biodiversity conservation (kamau, 2009; sampath, 2005). however, one of the main challenges of biodiversity conservation in the southern peripheral countries is biopiracy which simply can be defined as the ‘commercial use of genetic resources or indigenous knowledge without obtaining permission or properly paying the relevant community or country’ (mgbeoji, 2005; sharma, 2012). these issues are common in bottom up development and sustainable development projects implemented in many other southern peripheral countries (jalani, 2012; reimer & walter, 2013; thompson, 2008; waylen, gowan, & milner-gulland, 2009) and a large gap between practical achievements and expected goals of these projects can still be seen. taking this situation into consideration, this research focuses on carrying out a comparative analysis of challenges of biopiracy in the kudawa-sinharaja cbet site. 2. research methodology 2.1 research site the research field, the kudawa gnd which is an isolated area among all the administration units of sri lanka is located close to sinharaja. one of the route accesses to sinharaja is through kudawa gnd, namely, the kudawa-sinharaja entrance (see figure 1). 2.2 ‘qualitative research methodology’ and ‘inductive research approach’ the challenges of biopiracy in cbet in this site are based on deep-rooted socio-cultural, and socio-economic factors, which operate hidden in the society, besides, respondents were not necessarily ready to discuss them openly. therefore, in this research primary concern was to deal with ‘rich and deep’ primary data rather than ‘numeric’ data and much attention been paid to qualitative research methodology. this study targeted to collect philosophies on how ‘rich’ and ‘deep’ are intangible factors associated with biopiracy issues, such as cultural changes, local knowledge, geopolitics and local economic wealth. consequently, a ‘qualitative inductive research approach’ was selected as the dominant methodological approach of this research. there is a profound correlation between qualitative methodology and inductive research. in inductive research, first, data is collected using relevant qualitative data collecting methods and then findings are linked with relevant theories, discourses, and concepts. kumara. /journal of tropical forestry and environment vol. 6, no 02 (2016) 36-49 39 this is the opposite way to conducting a ‘quantitative-deductive research’, so it is called a ‘bottom up’ research approach (bryman, 2012; thomas, 2012). suitability of qualitative inductive research approach to this research is its ability to provide complex textual descriptions of how people experience a given research issue. it provides information about the ‘human’ side of an issue – that is, the often-contradictory behaviours, beliefs, opinions, and relationships of individuals. 2.3 data collecting methods: secondary data in the research is extracted from the following sources. a number of publications by local and international writers, especially those that include information about development discourses, alternative development, eco development, ecotourism, community forest management, joint forest management, tropical forest management etc. are used in the study. participant and direct observation, semi-structured interviews and focus group interviews were conducted as qualitative data collection methods for this research. altogether, 115 semi structured interviews were conducted in this research and each interviewee was provided with a consent form too. semi-structured interviews are presented by their categorical code. for instance, in ‘ssi10 site guides of sinharaja’, ‘ssi10’ stands for ‘semi structured interviewing number 10. ten focused group interviews also have been conducted to the primary data collection process of this research and it is also presented by categorical code as ‘fgi4 visitors (local)’: ‘fgi4’ indicates ‘focused group interviewing number 04’. a total of 293 participants have informed this research including 193 interviews. 2.4 sampling method semi-structured interviews use the ‘snow-balling’ sampling method. snow-balling is based on the metaphor that when a real snow ball is rolling down the hill, its size gradually increases until it approaches saturation (baker, 2012; cohen & arieli, 2011; dodds, 2014). thus, the researcher must gather enough data using a chain referral process until it approaches saturation (baltar & brunet, 2012). this method was useful in this research, since it helped to gather information from diverse respondents. as well, it helped to examine sensitive and confidential personal information important for the research objective (longhurst, 2009). 2.5 analysis a critical discourse analysis (cda) method was used to examine both primary qualitative data, which were collected through participant and direct observation, interviews as well as secondary data. the data was analysed using steps such as data understanding, categorizing, coding under themes, connecting with theories and discourses and described narratively (description/interpretation/explanation) (becker, 1958; dewalt, 2011; dey, 2003; may, 1997). classification of themes from the collected raw data can be recognized as a process (bryman, 2012). intensive reading, careful reading and re-reading were conducted as a procedure to identify patterns in the data to recognize separate themes (boyatzis, 1998; fereday & cochrane, 2008). 40 figure 1: location of the study area (drawn by max oulton) kumara. /journal of tropical forestry and environment vol. 6, no 02 (2016) 36-49 41 2.6. positionality and reflexivity the notion of ‘positionality and reflexivity’ is normally connected with qualitative research methodology (guillemin & gillam, 2004; walker et al., 2013). every human being lives in a highly connected socio-cultural and political network. the nature of that network is different from place to place, culture to culture and time to time. that means every human being enjoys a special socio-cultural, economic and political ‘position’. whatever they do, talk, write, create etc., that ‘position’ is naturally displayed in their work. the social researcher is also a human being who has a separate ‘position’ that depends on his/her own socio-cultural values, beliefs, feelings and thoughts (robert wood jonson foundation, 2012). many scholars have then argued that ‘position’ is exposed in many parts of a social research process (walker et al., 2013). since this research uses qualitative methodology, i (researcher) was concerned about my (researcher’s) ‘positionality’ through reflexivity. 3. results 3.1 capitalism, superimposed capitalism and individualism most of the kudawa villagers traditionally belong to the kitul tapping caste which is considered a low caste according to the traditional sri lankan caste hierarchy (silva, sivaparagasam, et al., 2009) and the villagers marry within the village and caste and this was easy as within sinhalese traditional feudal society ‘cross-cousin marriages’ are allowed (de munck, 1998; mcgilvray, 1982). this biological relationship helps to create ‘collectivism’ in the community and a ‘collectivist economy’. our village was an isolated community until 1980 and most of the villagers depended on kitul tapping and shifting cultivation for living and whole village acted as one unit [ssi42 senior kudawa villager (male -78 years old), 2012.11.01 (this statement was crosschecked and was proved by ssi22, 27, 31, 43, 26, 29, 13, 34,57, 41, 97, 94, 96)]. until the 1980s kudawa was an isolated society. when the ‘tea economy’ was introduced to kudawa after the 1980s, the villagers started growing tea on their private lands. later, cbet became popular in kudawa. in practice, implementation of cbet is challenged by ‘individualism’ in southern peripheral countries as a result of the influence of superimposed capitalism. this situation is common to the kudawa-sinharaja site. economically our village was rapidly developing after the 1980s, because of ecotourism and tea planting. currently, we have modern houses with facilities, and other infrastructure facilities such as roads, a medical centre, electricity etc. our village is open to the world and we freely interact with other outside communities. however, villagers become more and more isolated souls and our social relations are very poor now. everyone here is busy earning money [ssi4472 years old female kudawa resident, 2014.11. (this statement was cross-checked and was proved by ssi22, 27, 31, 43, 26, 29, 13, 34, 41, 97, 102, 101& fgi 03, 02)]. the change occurred in the village economy, and lifestyles of villagers due to ecotourism and it brought changes in peoples’ perspectives as well. at present, the villagers not only are in a rat race to earn money but also compete with each other to gain better social status. 42 3.2 biopiracy challenges and cbet genetic forest resource loss caused by wildlife trafficking and biological or genetic resource smuggling is one of the major environmental challenges faced by sri lanka and many other developing countries. most of the indigenous people in these countries, as underlined by the environmentalist interviewed above, are unaware of the biological value of the most of genetic resources available in their natural environments and the importance of protecting them for their own future. they see only the immediate economic value of these resources when they see how much they are paid by biopirates. thus, they are unaware of the size of the loss of their own future genetic resources when biopirates access these resources. this has made the people and the places they live in vulnerable to biopiracy and theft of genetic and biological resources (de carvalho, 2000; odek, 1994; posey & dutfield, 1996). sri lanka finds this problem to be one of the key challenges of practicing positive ecotourism in the country. with the development of the tourism sector , over the last decades, smuggling and illicit trade in valuable flora and fauna have increased (dellinger, 1995; pleumarom, 1999; subasinghe, 2013; tella & hiraldo, 2014). when ecotourism is developed in the kudawa-sinharaja site, loss of forest genetic resources and wildlife smuggling are also increased with the influence of superimposed capitalism and its values [this idea was proved by ssi22, 27, 31, 29, 13, 34, 41]. a growing number of biopirates venture into sinharaja for its genetic resources and they have understood that smuggling of biological material is easier and more successful if they cooperate with local indigenous people living at the forest peripheries. thus, biopirates enter the targeted country posing as innocent tourists and they do not hesitate to pay large sums of local money to villagers who deal with them in genetic resources or wildlife smuggling. regardless of all prevalent laws and regulations against bioprospecting, biopiracy, biological resource and wildlife smuggling, authorities have still failed to control these activities in the kudawasinharaja site because of the support given to bio-pirates by the local community. local villagers possess an excellent knowledge about local genetic resources and are well aware of forest geography. hence, they can quickly access the forest resources and collect them incognito. [ssi17-environmentalist, 2015.09.14 (this statement was cross checked and was proved by ssi72, 76, 78, 27, & fgi 05, 06)]. according to the records of the kudawa-sinharaja site, many international tourists have been charged with wildlife trafficking and biological and genetic resource theft (forest department, 2013a) but it has not discouraged the practice as is illustrated by these field observations. on 18th september 2012, around eleven thirty in the morning a newly joined local site guide informed the forester about suspicious behaviour of an overseas tourist couple who had entered the site as eco-tourists. the forest officers on duty at the time hurried to the exit of the site to investigate the matter. they found the couple, a middle-aged man, and a woman, at the exit and requested to check their baggage before leaving the park premises. at first, they refused and the officers explained their right to check the baggage. unwillingly and hesitantly, the couple opened their bags which were full of illegally collected orchid varieties of the park. then the forest officers asked the couple to follow them to the forest office with the baggage for further investigation. the couple kumara. /journal of tropical forestry and environment vol. 6, no 02 (2016) 36-49 43 seemed to be in a dilemma about what to do next and one of the forest officers tried to collect the baggage from the woman. at that time, the woman was very angry and she suddenly bit the hand of the forest officer (field note, 18.11.2012). they had collected more than 300 orchid plants including 18 rare endemic species to sri lanka. a case was filed against them in the court and it was later revealed that the couple were russian biologists with an excellent knowledge of sri lankan plant species and their local chauffeur guide had helped in the smuggling. they were proved guilty and fined slr 1,200,000.00 (about usd 9,213).the court ordered the convicted smugglers to leave the country immediately after paying the fine and their names have been blacklisted (shantha, padmabandu, & wijesooriya, 2012). since gyrinops species are recognized as highly valuable and producers of agarwood many countries approve limited permits for agarwood-producing tree products to prevent the species being endangered by trade (subasinghe, & hettiarachchi, 2013; 2015). agarwood is valuable resinous heartwood of thymalaeaceae family. owing to the very high price on the international market for other commercially used species of agarwood, gyrinops walla has been identified as a substitute. recent information reveals that gyrinops walla smuggling has occurred in sri lanka from last few years. the highest single amount discovered to be exported was 13,489 kg as recorded in may 2013. the data obtained from sri lanka police and customs depicts that over 17,500 kg of gyrinops walla had been harvested in the last 12 months (subasinghe, 2014). gyrinops walla is the only agarwood producing tree species of sri lanka (subasinghe, & hettiarachchi, 2015) and it grows freely in sinharaja. even if this species has been recorded in some areas of south india, at present gyrinops walla can only be seen in sri lanka (subasinghe, hettiarachchi & rathnamalala, 2012). as there are many freely growing gyrinops walla trees in the kudawa-sinharaja site, paid local people enter the site looking for these trees to extract its resin. within the last few years, a large number of gyrinops walla trees have been destroyed from the harvest and smuggling of agarwood from the country (dharmadasa, siriwardana, samarasinghe, & adhihetty, 2013; subasinghe, 2014). this research reveals that many locals are also involved in collecting agarwood, owing to its high demand and market value, which is even higher than the value of a gold sovereign (for the same weight) in sri lanka. during this field study, many local villagers and foreign tourists who were involved in gathering agar wood, which later deforms the gyrinops walla tree, were arrested by the police with the support of forest officers. the issue of gyrinops walla smuggling gradually increased and had become a serious biological issue by the middle of 2014. for example, three local villagers were arrested on 18.01.2014 by the sri lankan police with their collected gyrinops walla resins and at a rough government estimate, the market value of the collected resins was over slr 100,000,000.00 (us$ 767,725.00). however, these local villagers were ready to sell collected gyrinops walla resin for 5,000,000.00 rs (around us$ 38,400) which was only one twentieth of the real market value (ariyadasa, 2014). issues of biopiracy have also greatly increased within the last few years in the kudawasinharaja site as well as in other rain forest areas of the country. for example, a new trend of 44 spotted bow-finger gecko (cyrtodactylus triedra) smuggling was observed after 2012. this reptile is an endemic, rare and attractive species that can be seen in the rain forests of sri lanka (de silva, 2006). during the years 2013 and 2014, many local villagers and some overseas tourists have been arrested by the police for spotted bow-finger gecko smuggling [ssi21, 2012.09.24] figure 2: villagers’ vadi (prohibited temporary huts) inside sinharaja and tools used for gyrinops walla gathering figure 3. processing gathered gyrinops walla for trade photographed by damith kodithuwakku and published here with author’s permission 4. discussion development of ecotourism practices have created a new socio-economic structure in the kudawa-sinharaja site with superimposed capitalist values. this structure is different from western capitalism or the traditional sri lankan socio-economic system. as revealed in the research, superimposed capitalism has contributed to create an individualistic as well as consumeristic society and the traditions of the kudawa gnd communities nourished by traditional cultural and social values based on collectivism eroded rapidly. this sort of individualistic culture which is characterised by great competition among its members (even though they are related to each other either by descent or marriage) for economic status out of social envy can be identified as a major challenge in effective implementation of cbet (foucat, 2002; higham, 2007; jamal et al., 2006; nick, 2005; ross & wall, 1999). it challenges kumara. /journal of tropical forestry and environment vol. 6, no 02 (2016) 36-49 45 achievement of realistic cbet targets in the kudawa-sinharaja site, so that benefit and resource distribution issues, environmental vulnerability and unethical ecotourism practices become prominent. development of ecotourism in kudawa-sinharaja has opened the biodiversity rich sinharaja rain forest to gene pirates and thus the virgin forest is prone to bioprospecting, biopiracy and wildlife smuggling. even if some scholars have theoretically identified ‘ecotourism’ as a biosecurity management strategy (fennell, 2007; hall, 2007; hill & gale, 2009), in practice the opposite has occurred in many southern peripheral countries of africa, latin america and asia (cater, 2004). regardless of all the strong policies and laws on biopiracy, sri lanka is still battling with gene pirates and the legal mechanism has not helped to resolve the problem totally (forest department, 2013a). in this situation, ‘community empowerment’ and ‘collective leadership’ theories can be used to design community based biodiversity protection programmes as a part of cbet projects implemented in the forest areas to minimize vulnerability. however, it should be noted here that changing socio economic values of the local communities of the kudawa gnd under superimposed capitalism could hinder the development of such community-based programmes. therefore, educational and awareness raising programmes are necessary to help local people to recognize issues of biopiracy. if local villagers are capable of understanding the actual market values of genetic resources in their native lands, they would not be so easily cheated by genetic smugglers. on the other hand, the government together with the forest department can implement community-based programmes to plant marketable flora species like gyrinops walla outside the reserve for international trade, which would benefit community members as well as the country’s economy without clear understanding of the individualistic social structure of kudawa gnd, any cbet project will be unable to achieve sustainable development goals. some scholars have suggested to ‘redesign ecotourism’ practice, with special attention given to the concepts of ‘cultural equity’ and ‘participatory practice’ in order to minimise such an issue (jamal et al., 2006). as lappe explained, political and economic systems can be re-arranged and designed like a ‘home garden, so that community structures can be redesigned under the notion of ‘social empowerment’ and ‘collective responsibility’ (lappé, 2010, 2011, 2013). this view is useful to rearrange the cbet here. 5. conclusion data analysis of this research discloses biopiracy issues as theoretical and practical socioeconomic challenges to cbet associated with sustainable bottom up development approach. implementation of sustainable and bottom up development ideologies based on western alternative development approaches, can bring western capitalism into the particular context in the form of superimposed capitalism along with project activities. most importantly, capitalist and superimposed capitalist values are ideologically against bottom up development values. based on the research analysis, one of the main argument is that sustainable development discourse suffers from its own ideological and theoretical weaknesses as it lacks a mechanism to face the values of western capitalism merging into sustainable and bottom up development measures. references ariyadasa, k.k., 2014. ten crores of gyrinops walla smuggling from sinharaja. lankadeepa (2014, january 18), p. 1. baker, s., 2012. politics of sustainable development. oxford, uk: routledge. 46 baltar, f., & brunet, i., 2012. social research 2.0: virtual snowball sampling method using facebook. internet research, 22(1), 57-74. becker, h.s., 1958. problems of inference and proof in participant observation. american sociological review, 23(6), 652-660. boyatzis, r.e., 1998. transforming qualitative information: thematic analysis and code development. london, uk: sage. brand, u., 2012. green economy–the next oxymoron? no lessons learned from failures of implementing sustainable development. gaia-ecological perspectives for science and society, 21(1), 28-32. brydon, d., 2004. postcolonialism now: autonomy, cosmopolitanism, and diaspora. university of toronto quarterly, 73(2), 691-706. bryman, a., 2012. social research methods (4th ed.). oxford , uk: oxford university press. cater, e., 2004. ecotourism: theory and practice. in a. a. lew, c. m. hall & a. m. williams (eds.), a companion to tourism (pp. 484-497). oxford, uk: john wiley & sons. chaperon, s., & bramwell, b. (2013). dependency and agency in peripheral tourism development. annals of tourism research, 40, 132-154. clark, r., 2008. dependency, network integration, and development. sociological perspectives, 51(3), 629-648. cohen, n., & arieli, t., 2011. field research in conflict environments: methodological challenges and snowball sampling. journal of peace research, 48(4), 423-435. dangal, s.p., & de silva, p.m.a., 2010. community forest management in sri lanka: lessons learnt and future direction. retrieved from http://www.forestrynepal.org/images/02%20presented%20papers%20and%20powerpoints/theme%201/paper/07%20dangal%20et%20al_sri%20lanka.pdf, accessed 26 june 2016. de carvalho, n.p., 2000. requiring disclosure of the origin of genetic resources and prior informed consent in patent applications without infringing the trips agreement: the problem and the solution. washington university journal of law & policy, 2(1), 371-401. de munck, v.c., 1998. lust, love, and arranged marriages in sri lanka. westfort, india: praeger publication. de silva, a., 2006. current status of the reptiles of sri lanka. fauna of sri lanka, 11(1), 134-163. dellinger, b. (1995). critical discourse analysis. retrieved from http://httpserver.carleton.ca/~mflynnbu/discourse_analysis/dellinger.htm, accessed 08 july 2016. dewalt, k. m., 2011. participant observation: a guide for fieldworkers (2nd ed.). lanham, md: roman & littlefield. dey, i., 2003. qualitative data analysis: a user-friendly guide for social scientists. london, uk: routledge. dharmadasa, r., siriwardana, a., samarasinghe, k., & adhihetty, p., 2013. standardization of gyrops walla (thymalaeaceae) newly discovered, fragrant industrial potential, endemic plant from sri lanka. world journal of agricultural research, 1(6), 101-103. dodds, k.j., 2014. global geopolitics: a critical introduction. oxford, uk: routledge. fennell, d.a., 2007. ecotourism. new york, ny: routledge. fereday, j., & cochrane, e.m., 2008. demonstrating rigor using thematic analysis: a hybrid approach of inductive and deductive coding and theme development. international journal of qualitative methods, 5(1), 80-92. fernando, s.l.j., & shariff, n.m., 2013. trends, environmental issues and challenges of ecotourism in sri lanka. paper presented at the the 2013 ibea, international conference on business, economics, and accounting, bangkok, thailand. retrieved from http://www.caalinteduorg.com/ibea2013/ejournal/053---slj_fernando&noresah_mohd_shariff--trends_environmental_issues_and.pdf, accessed 08 july 2016. forest department, 2013a. reports of sinharaja rain forest. ratnapura, sri lanka: kudawa forest conservation center kumara. /journal of tropical forestry and environment vol. 6, no 02 (2016) 36-49 47 forest department, 2013b. sinharaja world heritage forest. retrieved from http://www.forestdept.gov.lk/web/index.php?option=com_content&view=article&id=114&itemi d=116&lang=en#sinharaja, accessed 08 july 2016. forest department, 2014. forest department sri lanka. retrieved from http://www.forestdept.gov.lk/web/index.php?lang=en, accessed 06 july 2016. foucat, v., 2002. community-based ecotourism management moving towards sustainability, in ventanilla, oaxaca, mexico. ocean and coastal management, 45(8), 511-529 guillemin, m., & gillam, l., 2004. ethics, reflexivity, and “ethically important moments” in research. qualitative inquiry, 10(2), 261-280. gunatilleke, i., gunatilleke, c., & dilhan, m., 2005. plant biogeography and conservation of the southwestern hill forests of sri lanka. the raffles bulletin of zoology, 12(1), 9-22. hall, c.m., 2007. biosecurity and ecotourism. in j. e. higham (ed.), critical issues in ecotourism: understanding a complex tourism phenomenon (pp. 102-116). london, uk routledge. higham, j.e.s., 2007. critical issues in ecotourism: understanding a complex tourism phenomenon. london, uk: routledge hill, j.l., & gale, t., (eds.). 2009. ecotourism and environmental sustainability: principles and practice. farnham, uk: ashgate jalani, j.o., 2012. local people's perception on the impacts and importance of ecotourism in sabang, palawan, philippines. procedia-social and behavioral sciences, 57(1), 247-254. jamal, t., borges, m., & stronza, a., 2006. the institutionalisation of ecotourism: certification, cultural equity and praxis. journal of ecotourism, 5(3), 145-175. kahveci, g., ok, k., & yýlmaz, e., 2011. ecotourism and sustainable development of forests and forest villagers in turkey. retrieved from http://www.fao.org/docrep/article/wfc/xii/0708a1.htm, accessed 09 july 2016. kamau, e. c., 2009. sovereignty over genetic resources: right to regulate access in a balance, the case of kenya. revista internacional de direitoe cidadania, 3(1), 73-88. kumara, h. i. g. c. (2010). the policy intervention and the trends in forest utilization by local communities in sinharaja (unpublished master of philosophy). university of peradeniya, kandy, sri lanka. lappé, f.m., 2010. diet for a small planet. new york, ny: random house llc. lappé, f.m., 2011. the city that ended hunger. in m. gerwin (ed.), food and democracy (pp. 53). kraków, poland: polish green network. lappé, f.m., 2013. beyond the scarcity scare: reframing the discourse of hunger with an eco-mind. the journal of peasant studies, 40(1), 219-238. longhurst, r., 2009. interviews: in-depth, semi-structured. in n. j. thrift & r. kitchin (eds.), international encyclopedia of human geography (vol. 10, pp. 580-584). oxford, uk: elsevier science. lynam, t., jong, w. d., sheil, d., kusumanto, t., & evans, k. (2007). a review of tools for incorporating community knowledge, preferences, and values into decision making in natural resources management. ecology and society, 12(1), 5. retrieved from: http://www.ecologyandsociety.org/vol12/iss1/art5/, accessed 11 july 2016. may, t., 1997. social research: issues, methods, and process (2nd ed.). philadelphia, pa: open university press. mcgilvray, d.b., 1982. sexual power and fertility in sri lanka: batticaloa tamils and moors. in c. maccormack (ed.), ethnography of fertility and birth (pp. 25-73). london, uk: academic press. mgbeoji, i., 2005. global biopiracy: patents, plants, and indigenous knowledge. vancouver, canada: ubc press. ngece, k., 2011. community based ecotourism: what can the people of east africa learn from success stories elsewhere? nairobi, kenya: east african ecotourism development and conservation consultants 48 odek, j., 1994. bio-piracy: creating proprietary rights in plant genetic resources. journal of intellectual property law, 2(1), 141-181. pawłowski, l., 2012. do the liberal capitalism and globalization enable the implementation of sustainable development strategy? problemy ekorozwoju: studia filozoficzno-sozologiczne, 7(2), 7-13. pleumarom, a., 1999. the hidden costs of the ‘new’tourisms: a focus on biopiracy (third world network briefing paper for the seventh session of the uncsd). new york, ny: uncsd publication. posey, d.a., & dutfield, g., 1996. beyond intellectual property: toward traditional resource rights for indigenous peoples and local communities. ottawa , canada: idrc publication. reimer, j.k., & walter, p., 2013. how do you know it when you see it? community-based ecotourism in the cardamom mountains of southwestern cambodia. tourism management, 34(1), 122-132. robert wood jonson foundation. (2012). qualitataive research guidelines project retrieved from http://www.qualres.org/homerefl-3703.html, accessed 10 july 2016. ross, s., & wall, g., 1999. ecotourism: towards congruence between theory and practice. tourism management, 20(1), 123-132 samath, f., 2014. sri lanka: ngos face funding gap and government scrutiny, http://www.ipsnews.net/2011/03/sri-lanka-ngos-face-funding-gap-and-government-scrutiny/, accessed in 30 aguest 2014. shantha, a.l., padmabandu, w., & wijesooriya, a.u., 2012. orchid plant collectors of sinharaja have been punished. lankadeepa, p. 4. sharma, p.k., 2012. indigenous knowledge of plants and biopiracy in india. in r. gupta (ed.), plant taxonomy: past, present, and future (pp. 141). new delhi, india: teri press. silva, k.t., sivaparagasam, p.p., & thanges, p., 2009. caste discrimination and social justice in sri lanka: an overview (working paper series: vol. 3, no 6). new delhi, india: indian institute of dalit studies. retrieved from http://idsn.org/fileadmin/user_folder/pdf/new_files/publications_from_network/caste_discrimina tion_and_social_justice_in_sri_lanka__iids_working_paper_.pdf, accessed in 28 aguest 2016. subasinghe, s., 2014. agarwood production in gyrinops walla (walla patta): myths and reality. in d. jayawardana & u. subasinghe (eds.), proceedings of international forestry and environment symposium. (aliya resort and spa, sigiriya, sri lanka): university of sri jayawardanapura. subasinghe, s.m.c.u.p., 2013. plantation forestry in sri lanka: challenges and constraints. colombo, sri lanka: agm of institute of biology. subasinghe, s.m.c.u.p., & hettiarachchi, d.s. 2013. agarwood resin production and resin quality of gyrinops walla gaertn. int. j. agric. sci, (3) 357-362. subasinghe, s.m.c.u.p., & hettiarachchi, d.s., 2015. characterisation of agarwood type resin of gyrinops walla gaertn growing in selected populations in sri lanka. industrial crops and products (69), 76-79. subasinghe, s.m.c.u.p., hettiarachchi, d.s., & rathnamalala, e., 2012. agarwood-type resin from gyrinops walla gaertn: a new discovery. journal of tropical forestry and environment, (2) 4449. tella, j.l., & hiraldo, f., 2014. illegal and legal parrot trade shows a long-term, cross-cultural preference for the most attractive species increasing their risk of extinction. plos one, 9(9), 1-10. thomas, l.j., 2012. neoclassical development theory and the prebisch doctrine: a synthesis. american economist, 38(1), 75-81. thompson, p.m., 2008. conserving and restoring the benefits from bangladesh wetlands. in j. powell & c. short (eds.), 12th international association for the study of commons conference (pp. 14-18): university of gloucestershire, uk. vitarana, k.m., & rakaganno, r., 1997. sri lanka's forestry sector master plan. retrieved from http://ces.iisc.ernet.in/hpg/envis/doc97html/ecolankaforest811.html, accessed in 28 aguest 2016. walker, s., read, s., & priest, h., 2013. use of reflexivity in a mixed-methods study. nurse researcher, 20(3), 38-43. kumara. /journal of tropical forestry and environment vol. 6, no 02 (2016) 36-49 49 waylen, k.a., gowan, p.j.k.m., & milner-gulland, e.j., 2009. ecotourism positively affects awareness and attitudes but not conservation behaviours: a case study at grande riviere, trinidad. oryx, 43(3), 343-351. ziai, a., 2011. postcolonialism and development: disparate tales reconsidered development and change, 42(5), 1297-1306. dereje and duguma /journal of tropical forestry and environment vol. 9, no. 01 (2019) 27-36 27 woody species composition and natural regeneration status of ades forest, oromia regional state, west hararghe zone, ethiopia dereje o.a.1*, duguma i.d.2 1 department of biological science, school of biological science and biotechnology, collage of natural and computational science, haramaya university, ethiopia 2 department of molecular biology and biotechnology, school of biological science and biotechnology, collage of natural and computational science, haramaya university, ethiopia date received: 30-11-2018 date accepted: 18-05-2019 abstract this study was conducted at ades forest in west hararghe zone, ethiopia, for determining the woody species composition and regeneration status of the forest. systematic sampling method was used to collect vegetation data from 48 (20 m×20 m) main sample plots for woody species that was established along a transect line and spaced at 10 m altitudinal drop, from top to the bottom of the natural forest. inside the main plot (400 m2), subplots (5 m×5 m) were established to simplify the counting of seedlings and saplings. species abundance and environmental variables were recorded in each sample plot. a total of 48 woody plant species belonging to 42 genera and 29 families were identified. fabaceae family had the highest number of taxa followed by rosaceae and flacourtiaceae families. woody plant species densities for mature individuals were 197.9 ha-1, saplings 420 ha-1and 849.5 ha-1for seedlings. although over all regeneration status of woody plants of the forest revealed good regeneration status, the presence of anthropogenic disturbance in the area necessitates the need for conservation action in order to ensure sustainable utilisation and management of the forest. key words: regeneration, samplings, seedlings, woody species 1. introduction quantitative information on composition, distribution, and abundance of woody species is significant to understand the form and structure of a forest community. it is also very important for planning and implementation of conservation strategy of the forest community. the species richness and diversity of trees are fundamental to total forest biodiversity because trees provide resources and habitat for almost all other forest species (malik, 2014). in case of forest ecosystems, trees are responsible for the overall physical structure of habitats, and thus, they define fundamentally the templates for structural complexity and environmental heterogeneity (malik et al., 2016). forests are increasingly threatened as a result of deforestation, fragmentation, climate change and other stressors that can be linked to human activities such as agricultural expansion, forest clearance for fire wood, construction materials, timber and charcoal production (yonas, 2001; getachew and demel, 2005; liaison, 2013). these temporary benefit oriented deforestation is followed by land degradation and soil erosion which result in biodiversity loss (tadesse and demel, 2001; feyera, 2006; tadesse, 2008). in forest management, regeneration study is not only depicts the current status but also hints about the possible changes in forest composition in the future (malik and bhatt, 2016; sharma et al., 2014). survival and growth of seedlings and saplings determine the successful regeneration (good and good, 1972), which is perhaps the single most important step *correspondence: datomsa@yahoo.com tel: +251 932174621 issn 2235-9370 print / issn 2235-9362 online ©2019 university of sri jayewardenepura doi: https://doi.org/10.31357/jtfe.v9i1.3947 28 toward achieving long-term sustainability of forests (saikia and khan, 2013; malik, 2014; malik and bhatt, 2016;). the major problem in the mountain natural forest of ethiopia is habitat degradation. it includes various forms of land degradation, adverse human impacts on plant resources, deforestation, and lowering of the productive capacity of rangelands. other anthropogenic activities such as constructions of hill roads, forest fires, over grasing, lopping of trees for fodder and fuel wood, and removal of leaf and wood litter from the forest floor are also affecting plant diversity in the natural forest. reliable data on regeneration trends are required for successful management and conservation of natural forests (eilu and obua, 2005). forests and forest products should be used in a way that could not compromise or harm the coming generation. clearing of forest resources is accelerated as human needs became wider and wider. high level of dependency on agriculture, high rate of population growth and non-integrated investment activities are also factors that aggravated deforestation in ethiopia (ensermu and teshome, 2008). studies reported by (demel, 2001; yonas, 2001; fao, 2007) indicated that there are continuous deforestation and land degradation in ethiopia. due to low level of peoples’ awareness on the role that forests have in terms of ecosystem services, less attention has been given to their conservation. adequate awareness regarding wise use of forest resources should be given to the whole society so that some multipurpose endogenous and medicinally important plant species can be saved from local extinction. many studies have been conducted in different parts of the country to investigate the species composition, population structure and regeneration ecology of forests (tesfaye et al., 2002; simon and girma, 2004; ensermu and teshome, 2008; zegeye, et al., 2011). however, there is little scientific information available on woody species composition and regeneration status of natural forest at west hararghe zone, ethiopia. this study wase therefore aimed at assessing woody plant species composition and regeneration status of the ades natural forest. 2. materials and methods 2.1 the study area the study was conducted on ades natural forest, located in western hararghe zone, oromia regional state, ethiopia. the zone is 371 km from addis ababa, has an average altitude of 1,600-3,100 meters above sea level and average annual rain fall of 250-900 ml and average annual temperature of 1618o c. the area is mainly covered by an irregular topography with depressions, numerous chain mountains, flat lands, gorges, scattered trees and dense shrubs of patch natural vegetation. figure 1: map of the study area. dereje and duguma /journal of tropical forestry and environment vol. 9, no. 01 (2019) 27-36 29 2.2 floristic and structural data collection reconnaissance survey was made across the ades natural forest in order to obtain vegetation patterns and determine representative sampling sites. vegetation data were collected using a systematic sampling method as described by (kent and coker, 1992). sampling was done along an altitudinal gradient between 3100 m and 1600 m above sea level. the data of vegetation attributes were measured for trees and shrubs, and recorded using twenty by twenty meter size plots which were established along a transect line, starting from top to the bottom of the natural forest. all the woody plant species encountered in each sample plot were recorded using vernacular or local names and code was given for unknown specimen. sampling plotess were arranged along transects line, which were spaced at 10 m altitudinal drop, along the elevation gradient of the forest. inside the major plot (20 m×20 m), sixteen subplots were established. we partitioned the major quadrats (400 m2) into sixteen, each 25 m2 (5 m×5 m), to ease the counting of seedlings and saplings. the undergrowths of woody species with height less than 1 m were considered as seedlings, height greater than 2 m are considered as matures trees/shrubs and those in between 1-2 m and dbh<2 cm are considered as sapling (singhal, 1996). the height of seedlings and saplings were measured using a meter tape and for trees visual estimation was made. environmental variables such as altitude and geographical coordinates were also measured for each plot using geographical position system (gps) (kent and coker, 1992).specimens were collected, pressed, dried and brought to the haramaya university herbarium for identification and to national herbarium (eth), addis ababa university for further authentication. the specimens were dried in the dryer, kept in a deep freezer for 72 hours and identified referring to the volumes of flora of ethiopia and eritrea and finally documented. 2.3 data analysis method all individuals of plant species recorded in all quadrants were used in the analysis of woody species composition and regeneration status of the forest. after all the seedlings, saplings and mature plants found in each established quadrant were counted, identified and recorded, their density and ratio of seedlings to adult individuals seedlings to saplings and saplings to mature individuals were calculated. in order to use the regeneration analysis outcomes for priority setting, woody plant species in the study area were grouped into three regeneration status classes (priority classes for conservation) based on the method reported by (simon and girma, 2004). based on the result, regeneration status of the forest was determined and appropriate conservation and management methods were suggested. 3. results and discussions the result of vegetation composition study showed that ades natural forest has different woody plant species. some of the dominant species in this natural forest were found to be juniperus procera, podocarpus falcatus, croton macrstachyus, and maytenus sp. the vegetation composition varied with altitude changes. high and dense forest with dominant secondary generation of podocarpus falcatus at lower and middle altitudes to juniperus procera and croton macrstachyus with intermingled of other species at higher altitudes. 3.1 woody plant species composition a total of 48 woody plant species were recorded from ades natural forest in current study. out of these, 15 (52.08%) species were trees while 23 (47.92%) species were shrubs. the list of all species is given in appendix 1. the identified species were belonging to 42 genera and 29 families. fabaceae was the most dominant family, contributed 5 (16.7%), followed by rosaceae and flacourtiaceae both represented by 4 (13.7%) families. 30 3.2 regeneration status of woody species in ades forest the status of tree population and the persistence of existing species in future forest composition are dependent on sufficient amount of age categories of plant species. the total density of seedlings (849.5 individuals ha-1) was found to be higher than the saplings (420 individuals ha-1) and adults (197.9 individuals ha-1) in ades natural forest, thus exhibiting overall ‘good’ regeneration condition of woody plant species at the community level (figure 2). as far as the regeneration status of each species is concerned and based on the categories used by dhaulkhadi et al. (2008) and chauhan et al. (2008), out of the 48 wood species, twenty four (50%) woody species achieved good regeneration, three (6.3%) species had fair regeneration, four (8.5%) had poor regeneration, seven (14.6%) no regeneration, and ten (20.8%) were considered as ‘new’ species in ades forest. in the current study, seedling density ha-1 is greater than both sapling and mature density and sapling density is greater than mature tree (i.e. density of seedling>sapling>mature trees/shrubs) within the study area, which indicate a successful regeneration potential of the forest. according to dhaulkhadi et al. (2008), a given forest had good regeneration if seedling is greater than sapling and mature tree/shrubs (seedling density>sapling density>mature; fair regeneration if seedling>or≤sapling<mature tree; poor regeneration if seedling<sapling≥or ≤mature tree; and no regeneration if species are represented only by adult/mature trees. in line with this evidence, ades forest has good regeneration status since seedling density ha-1 is greater than sapling and mature tree/shrubs for a general count. however, during data collection, some evidence of biotic disturbance like selective cutting of some woody species by local communities, open grassing area, many paths in the forest that can damage the seedling development in to adult individuals in the forest were observed. mature density might have decreased in near future as a result of selective cutting of trees by local people for different purposes like construction, charcoal production, farming materials, medicinal use and others. even if most of the species showed good regeneration status, however, some species like prunus africana, and olea europaea subsp. cuspidata were represented only by seedling and sapling stage which indicates selective using of this species at mature stage by local peoples. there is also encroachment of forested area as a result of farming activities. unless appropriate management activities are undertaken, the regeneration status of this forest will be threatened in the future. regeneration of woody plants refers to the recruitment, survival and growth of seedlings and/or sprouts of these plants in a given area (lalfakawma, 2010). when the source of this process is occurring in nature from seeds or other vegetative propagules, the regeneration is known as natural regeneration. harmer (2001) defined natural regeneration as ‘‘the establishment of trees from seeds that fall and germinate in situ’’. seedlings represent the final stage in the process of regeneration from seed (kitajima and fenner, 2000). the density values of seedling and saplings are considered as regeneration potential of the species (robi, 2016). the successful regeneration of a given forest requires the occurrence of a sufficient number of young trees, saplings and seedlings in population (hanief et al., 2016). germination, growth and survival of any species is confined to a particular range of habitat conditions and the extent of those conditions is a major determinant of its geographic distribution. both climatic and biotic factors interference influences the regeneration of different species in the forest. higher seedling density values get reduced to sapling due to biotic disturbances and competition for space and nutrients. the regeneration status of a forest was summarised based on the total count of seedlings, saplings and adult individuals of each species across all plots. this finding supported the research by habtam and ali (2015), which stated as, compared to seedling individuals there were less sapling individuals implying the death of most seedlings before reaching sapling stage due to factors such as human interventions, browsers, grazers, fire and nature of the seeds. calculation of the ratio among the seedling, sapling and mature tree can provide information about the distribution of age categories and the regeneration status of the species (chauhan et al., 2008; robi, dereje and duguma /journal of tropical forestry and environment vol. 9, no. 01 (2019) 27-36 31 2016). in line with this, the ration of seedling to sapling, seedling to mature tree and sapling to mature tree of the species was calculated and the result was 2.02:0.49, 4.29:0.23 and 2.12:0.47, respectively. these revealed that the distribution of seedling individuals is greater than both sapling and mature tree or shrub individuals. this showed that there was sufficient number of seedling and sapling available as a potential for regeneration and recruitment (figure 2). hanief et al. (2016) stated that the successful regeneration of a given forest requires the occurrence of a sufficient number of young trees, saplings and seedlings in population. hence, in this study there is sufficient amount of seedling and sapling is available as a potential for successful regeneration this forest (figure 2). figure 2: over all regeneration status of ades forest. the regeneration status of plant species in a community can be accessed from the total population dynamics of seedlings and saplings in the forest community (tesfaye et al., 2002; duchok et al., 2005). the overall pattern of population dynamics of seedlings, saplings and adults of a plants species can exhibit the regeneration profile, which is used to determine their regeneration status (khan et al., 1987; tamirat, 1994). a population with sufficient number of seedlings and saplings depicts satisfactory regeneration behavior, while inadequate number of seedlings and saplings of the species in a forest indicates poor regeneration (khan et al., 1987; tripathi and khan, 2007). pokhriyal et al. (2010), mentioned that research in this field contributes to planning conservation and decision making in forest resource management programs. the presence of good regeneration potential shows stability of the species in the environment. climatic factors and biotic interferences influence the regeneration potential of different species in the forest. such study should be supported since it has important implications for the management of natural forests. based on the presence or absence of seedling, sapling or both, woody species recorded in ades forest were grouped into three priority classes for conservation. these are priority class 1: those species with no seedling and sapling, priority class 2: those with seedlings but no sapling, and priority class 3: those with both seedlings and saplings>1 individual ha-1 (table 1). the first and second priority classes, therefore, need due attention in order to save them from local extinction. according to harmer (2001), analyses of vegetation structure using growth stages of trees as seedlings, saplings and mature trees within a population can be one of the elements of diversity that allows or denies the chance of rapid recovery after disturbances. seedling sapling mature d e n si ty ( in d iv id u a ls h a -1 ) age categories 32 table 1: species conservation priority classes. priority class 1 priority class 2 priority class 3 allophylus abyssinicus asparagus africanus apodytes dimidiate bersama abyssinica maesa lanceolata brucea antidysenterica dovyalis verrucosa millettia ferruginea calpurnea aurea ficus sur oncoba spinosa carissa spinarum halleria lucida psydrax schimperiana croton macrostachyus rhus natelensis rhus glutinosa dombeya torrid schefflera abyssinica teclea nobilis dovyalis abyssinica vernonia amygdalina ekebergia capensis euphorbia ampliphylla euphorbia tirucalli juniperus procera lepidotruchilia volkensii maytenus sp. myrica salicifolia nuxia congesta olea europaea l. subsp. cuspidate osyris quadripartite pittosporum viridiflorum podocarpus falcatus prunus africana pterolobium stellatum rhamnus staddo rubus steudneri scolopia theifolia vangueria madagascariensis vernonia urticifolia those species listed under the first priority class (allophylus abyssinicus, bersama abyssinica, dovyalis verrucosa, ficus sur, halleria lucida, rhus natelensis and schefflera abyssinica), need urgent conservation and management activities while plants listed under priority classes 2 and 3 need follow up management. according to grau (2000), there are different factors which cause threats to the regeneration of some woody species. among these, endogenous factors like vegetation structure and species interaction between adults and at lower age are the major threats. although the relative abundance, growth and distribution of seedlings and/or saplings are important in determining species that replace the canopy, abundance of seedlings and/or saplings should not at all considered as an indicator of the ultimate establishment of young individuals. the reason for this is that, the establishment of many indigenous woody plants seedlings and/or saplings is not easy to regenerate because of unfavorable microhabitat. saxena and singh (1984) stated that population structures, characterised by the presence of a sufficient population of seedlings, saplings and young trees, indicate a successful regeneration of forest species. the current study result confirmed this idea, since seedlings represented by the highest proportion followed by saplings and matured individuals respectively. the distribution of seedlings is greater than that of sapling and mature individuals whereas that of matured individuals are the least one. sapling density might decrease as a result of biotic or abiotic factors that prevent the development of seedlings to saplings in the area. for example, no saplings were recoreded for maesa lanceolata, millettia ferruginea, oncoba spinosa, rhus glutinosa, psydrax schimperiana, schefflera abyssinica, teclea nobilis and vernonia amygdalina in the forest. this might be because of biotic disturbance or environmental factors. studying the regeneration status of forest has important implications for the management of natural dereje and duguma /journal of tropical forestry and environment vol. 9, no. 01 (2019) 27-36 33 forests. pokhriyal et al. (2010), mentioned that research in this field contributes to planning conservation and decision making in forest resource management programs. the presence of good regeneration potential shows stability of the species in the environment. according to dhaulkhandi et al. (2008), the density values of seedlings and saplings are considered as regeneration potential of the species. climatic factors and biotic interferences influence the regeneration of different species in the vegetation. the current result showed that six species, crotalaria laburnifolia, combretum molle, hagenia abyssinica, maytenus undata, rosa abyssinica, and indigofera rothii (12.5%) of the total 48 woody species were not represented by seedling stages, while seven individual species in the forest (14.6%) were not represented by both seedlings and saplings. these species include: allophylus abyssinicus, bersama abyssinica, ficus sur, dovyalis verrucosa, halleria lucida, rhus natelensis, and schefflera abyssinica. on the other hand eight species (16.7%) of the total were not represented by sapling stage in ades forest. these species include: asparagus africanus, maesa lanceolata, millettia ferruginea, oncoba spinosa, psydrax schimperiana, rhus glutinosa, teclea nobilis, vernonia amygdalina. individual species with such type of population pattern are poor in their regeneration and recruitment potential since there are no juveniles which tend to become a mature individuals in the future unless appropriate conservation and management actions undertaken. this might be due to over grazing by both wild and domestic animals or other factors such as lack of safe site for seed recruitment. in the contrast, most species 26 (54.2%), were represented by at least one or greater than one of both seedling and sapling stages. as a result, these were species with good regeneration status than those without seedling or/and sapling stages (table 1). species that lack seedling, sapling or both have poor/no regeneration status so that they are either under threat of local extinction or may prefer coppices or sprouts as the strategy of survival. for exaple, prunus africana, rhus glutinous, teclea nobilis, and scolopia theifolia were species that can reproduce by coppices or sprouts (recorded from observation during data collection on the field). similar findings were also reported by (simon and girma, 2004; dereje, 2007; teshome, 2009). 4. conclusion assessment of natural regeneration status of woody species in the forest is important for their management, conservation, and sustainable utilisation of forest and forest products. in this study, the overall regeneration potential of trees/shrubs plant species revealed that contribution of seedlings to the total population was highest followed by saplings and adult trees. in general, it shows that, regeneration status of woody species in the study area is “good” and the future communities may be sustained unless there is any challenging environmental stress or anthropogenic activities. however, the growth, survival, and reproduction potential of the tree species showing “poor” or “no” regeneration may be at risk in the near future. therefore, appropriate management plan is required for their conservation and sustainable utilisation. acknowledgement authors are thankful to haramaya university, office of research affairs for granting this research project as well as to team leader for his comments and suggestions. the authors are also highly appreciative to ades forest gardner, local communities and field guides for allowing us to collect plant samples, giving information and for their assistants during plant sample collection. references chauhan, d., dhanal, c., singh, b., chauhan, s., todaria, n. and khalid, m., 2008. regeneration and tree diversity in natural and planted forests in a terai -bhabhar forest in katarniaghat wildlife sanctuary, india. tropical ecology, 49:53-67. demel, t., 2001. deforestation, wood famine, and environmental degradation in ethiopia’s highland eco systems: urgent need for action. northeast african studies, 8:53-76. 34 dereje, d., 2007. floristic composition and ecological study of bibita forest southwest ethiopia. msc. thsis, addis ababa university, addis ababa. dhaulkhandi, m., dobhal, a., batt, s. and kumar, m., 2008. community structures are regeneration potential of natural forest site in gangotri, india. journal of basic and applied sciences, 4:49-52. duchok, r.k., kent, a.d. and khumbongmayum, a., 2005. population structure and regeneration status of medicinal tree illicium griffithii in relation to disturbance gradients in temperate broadleaved forest of arunachal pradesh. current science, 89:673-676. eilu, g. and obua, j., 2005. tree condition and natural regeneration in disturbed sites of bwindi impenetrable forest national park, southwestern uganda. tropical ecology, 46:99-111. ensermu, k. and teshome, s., 2008. interfaces of regeneration, structure, diversity and use of some plant species in bonga forest: a reservoir for wild coffee gene pool. sinet: ethiopian journal of science, 31:121-134. fao (food and agriculture organization), 2007. state of the world’s forests, fao, forestry department, 144. feyera, s., 2006. biodiversity and ecology of afromontane rain forests with wild coffee arabica l. populations in ethiopia. ecology and development series, cuvillier verlag, gottingen. getachew, t. and demel, t., 2005. the influence of logging on natural regeneration of woody species in harena montane forest, ethiopia. ethiopian journal of biological science, 4:59-73. good, n.f. and good, r.e., 1972. population dynamics of tree seedlings and saplings in mature eastern hardwood forest. bulletin of the torrey botanical club, 99:172-178. grau, h.r., 2000. regeneration pattern of cedrela lilloi (meliaceae) in northwestern argentina subtropical montane forest. journal of tropical ecology, 16:227-242. habtam, g. and ali, s., 2015. floristic composition, structure and regeneration status of achera natural forest in chilga district, northwest ethiopia. ethiopian journal of biological science, 14:217231. hanief, m., bidalia, a., meena, a. and rao, k.s., 2016. natural regeneration dynamics of dominant tree species along an altitudinal gradient in three different forest covers of darhal watershed in north western himalaya (kashmir), india. tropical plant research journal, 3:253-262. harmer, r., 2001. the effect of plant competition and simulated summer browsing by deer on tree regeneration. journal of applied ecology, 38:1094-1103. kent, m. and coker, r., 1992. vegetation description and analysis: a practical approach. crc press, inc., london. khan, m.l., rai, j.p.n. and tripathi, r.s., 1987. population structure of some tree species in disturbed and protected subtropical forests of northeast india. acta oecologica oecologia applicata, 8:247-255. kitajima, k. and fenner, m., 2000. ecology of seedling regeneration. in fenner, m. (ed.) seeds: the ecology of regeneration in plant communities 2nd edition. cabi publishing. lalfakawma, 2010. disturb and perish, conserve and flourish regenerating forests: a review science vision, 10:3-7. liaison, l., 2013. climate change, biodiversity and land degradation.conservation on biological diversity. unccd, 3. malik, z.a., 2014. phytosociological behaviour, anthropogenic disturbances and regeneration status along an altitudinal gradient in kedarnath wildlife sanctuary (kwls) and its adjoining areas. phd desertion. uttarakhand: hnb garhwal university srinagar garhwal. malik, z.a. and bhatt, a.b., 2016. regeneration status of tree species and survival of their seedlings in kedarnath wildlife sanctuary and its adjoining areas in western himalaya, india. tropical ecology, in press. malik, z.a., pandey, r. and bhatt, a.b., 2016. anthropogenic disturbances and their impact on vegetation in western himalaya, india. journal of mountain science, 13:69-82. dereje and duguma /journal of tropical forestry and environment vol. 9, no. 01 (2019) 27-36 35 pokhriyal, p., uniyal, p., chanuahan, d.s. and todaria, n.p., 2010. regeneration status of tree species in forest of phakot and pathri rao watersheds in garhwal himalaya. current science, 98:171-175. robi, m.k., 2016. the status of an ethiopian endemic plant vepris dainellii (pichi-serm.) kokwaro, in arba minch natural forest, southern ethiopia. international journal of multidisciplinary, 311:2024. saikia, p. and khan, m.l., 2013. population structure and regeneration status of aquilaria malaccensis lam. in home gardens of upper assam, northeast india. tropical ecology, 54:1-13. saxena, a.k. and singh, j.s., 1984. tree population structure of certain himalyan forest association and implications concerning their future compostion. vegetation, 58:61-69. sharma, c.m., mishra, a.k., prakash, o., dimri, s. and baluni, p., 2014. assessment of forest structure and woody plant regeneration on ridge tops at upper bhagirathi basin in garhwal himalaya. tropical plant research, 1:62-71. simon, s. and girma, b., 2004. composition, structure and regeneration status of woody species in dindin natural forest, southeast ethiopia: an implication for conservation. ethiopian journal of biological science, 3:15-35. singhal, r.m., 1996. soil and vegetation studies in forests. icfre puplications, debra dun, 62-65. tadesse, w. and demel, t., 2001. the forest coffee ecosystems: ongoing crises, problems and opportunities for coffee gene conservation and sustainable utilization. in: imperative problems associated with forestry in ethiopia, workshop proceedings. biological society of ethiopia, addis ababa, 131-142. tadesse, w., 2008. floristic composition environmental factors characterizing coffee forests in southwest ethiopia. forest ecology and management, 255:2138-2150. tamrat, b., 1994. studies on remnant afromontane forests on the central plateau of shewa, ethiopia. phd. thesis. uppsala university, sweden, 59 tesfaye, g., teketay, d. and fetene, m., 2002. regeneration of 14 tree species in harenna forest, southeast ethiopia. flora, 197:461-474. teshome, g., 2009. floristic composition and structure of gendo (gura tirigni) moist montane forest, east wollega zone, oromia region, ethiopia. msc thesis, addis ababa university, addis ababa. tripathi, r.s. and khan, m.l., 2007. regeneration dynamics of natural forests. a review, proceedings of the indian. national science academy, 73:167-195. yonas, y., 2001. status and prospects of forest policy in ethiopia. in: imperative problems associated with forestry in ethiopia, pp. 9-30, (biological society of ethiopia,ed.). workshop proceedings, biological society of ethiopia, addis ababa. zegeye, h., teketay, d. and kelbessa, e., 2011. diversity and regeneration status of woody species in tara gedamand abebaye forests, northwestern ethiopia. journal of forestry research, 22:315328. appendix appendix 1: list of woody species collected from ades forest with their age categories. scientific name family local name h sdl sap mat allophylus abyssinicus (hochst.) radlk. sapindaceae embis (amh.) t 0 0 2 apodytes dimidiate e. mey. ex. am icacinaceae ararsaa (or) s 22 21 0 asparagus africanus lam. asparagaceae sariiti (or.) s 2 0 0 bersama abyssinica fresen. melianthaceae waakkaa (or) t 0 0 9 brucea antidysenterica j.f. mill. simaroubaceae qommongo (or) t 2 1 0 calpurnea aurea (ait.) benth. fabaceae ceekaa (or.) s 74 71 0 carissa spinarum l. apocynaceae agemssa (or.) s 44 31 1 combretum molle g.don combretaceae maldhisaa (or.) s 0 1 0 crotalaria laburnifolia l. fabaceae s 0 1 0 croton macrostachyus del. euphorbiaceae bekenissa (or.) t 17 3 8 dombeya torrida (j.f.gmel.) p.bamps sterculiaceae daanisa(or.) t 6 3 3 36 scientific name family local name h sdl sap mat dovyalis abyssinica (a. rich.) warb. flacourtiaceae shimbirqoli (or.) s 77 35 0 dovyalis verrucosa (hochst.) warb. flacourtiaceae liqqimme (or) t 0 0 1 ekebergia capensis sparrm. meliaceae sombo (or.) t 21 19 2 euphorbia ampliphylla pax. euphorbiaceae adaamii (or.) t 2 1 0 euphorbia tirucalli l. euphorbiaceae caadaa (or.) t 21 19 2 ficus sur forssk. moraceae harbuu (or.) t 0 0 2 hagenia abyssinica (bruce) j.f.gmel. rosaceae hexoo (or.) t 0 1 4 halleria lucida l. scrophularaceae s 0 0 24 indigofera rothii baker fabaceae ooshee (or.) s 0 2 0 juniperus procera hochst. ex. a. rich. cuppressaceae getera (or.) t 36 7 112 lepidotruchilia volkensii (gurke) ler’y meliaceae miixoo (or.) s 19 16 3 maesa lanceolata forssk myrsinaceae abbayyi (or.) t 5 0 5 maytenus sp. celasteraceae qaxamme (or.) s 105 80 13 maytenus undata (thunb.) blackelock celasteraceae wontofulasa (or.) t 0 1 0 millettia ferruginea (hochst.) bak. fabaceae birbirraa (or.) t 2 0 myrica salicifolia hochst ex. a. rich. myricaceae macheensoo (or.) s 33 24 0 myrsine africana l. myrsinaceae kechemo (amh.) s 77 9 0 nuxia congesta r. br. ex fresen. loganiaceae machalo(or.) t 1 1 0 olea europaea l. subsp. cuspidata (wall. ex. g. don.) cif. oleaceae ejerssa (or.) t 77 4 8 oncoba spinosa forssk flacouriaceae garabagush (or.) t 3 0 13 osyris quadripartita decn. santalaceae watto (or.) s 7 5 0 pittosporum viridiflorum sims pittosporaceae dhamaye (or.) t 6 1 1 podocarpus falcatus (thunb) r.b. ex. mirb. podocarpaceae birbirssa (or.) t 257 141 106 prunus africana (hook. f.) kalkm. rosaceae muka gurach(or.) t 123 13 2 psydrax schimperiana (a.rich) bridson rubiaceae gallee (or.) s 1 0 pterolobium stellatum (forssk.) brenan fabaceae kuntir (amh.) s 1 2 0 rhamnus staddo a. rich rhamnaceae sibiillo (or.) t 2 1 0 rhus glutinosa a. rich. anacardiaceae tatessa (or.) t 2 0 4 rhus natelensis meikle anacardiaceae nanfaree (or.) s 0 0 1 rosa abyssinica lindley rosaceae qajima (or.) s 0 1 0 rubus steudneri schweinf. rosaceae s 7 6 0 schefflera abyssinica (a.rich.) harms araliaceae habaratuu (or.) t 0 0 1 scolopia theifolia gilg. flacourtiaceae qillisaa (or.) t 193 110 44 teclea nobilis del. rutaceae hadheessa (or.) s 1 0 2 vangueria madagascariensis gmel. rubiaceae ababunee (or.) s 360 164 0 vernonia amygdalina asteraceae s 5 0 3 vernonia urticifolia a. rich. asteraceae reji or.) s 3 3 0 total 29 family 48 spps 1614 798 376 h=habit, t=tree, s=shrub, sdl=seedlings, sap=saplings, mat=matured. sen and bhakat/ journal of tropical forestry and environment vol. 10 no. 01 (2020) 17-39 _____________________________________________ *correspondence: uudaysen@gmail.com tel: +91 9002524806 © university of sri jayewardenepura 17 floristic and phytoclimatic study of an indigenous small scale natural landscape vegetation of jhargram district, west bengal, india u.k. sen* and r.k. bhakat ecology and taxonomy laboratory, department of botany and forestry, vidyasagar university, west bengal, india date received: 29-09-2019 date accepted: 28-06-2020 abstract sacred groves are distinctive examples of biotic components as genetic resources being preserved in situ and serve as secure heavens for many endangered and endemic taxa. from this point of view, the biological spectrum, leaf spectrum and conservation status of the current sacred grove vegetation, sbt (swarga bauri than) in jhargram district of west bengal, india, have been studied. the area's floristic study revealed that sbt‟s angiosperms were varied and consisted of 307 species belonging to 249 genera, distributed under 79 families of 36 orders as per apg iv. fabales (12.05%) and fabaceae (11.73%) are the dominant order and family in terms of species wealth. biological spectrum indicates that the region enjoys “thero-chamae-cryptophytic” type of phytoclimate. with respect to the spectrum of the leaf size, mesophyll (14.05%) was found to be high followed by notophyll (7.84%), microphyll (7.19%), macrophyll (7.84%), nanophyll (6.86%), leptophyll (6.21%), and megaphyll (2.29%). the study area, being a sacred grove, it has a comparatively undisturbed status, and the protection of germplasm in the grove is based on traditional belief in the social system. keywords: biodiversity conservation, biological spectrum, leaf spectra, life-form, sacred grove 1. introduction sacred groves are indigenous small scale natural landscape of native vegetation kinds that are traditionally protected and managed by local populations. a range of taboos and prohibitions are used to preserve biodiversity in „sacred groves‟ (colding and folke, 1997, 2001; berkes, 2009). many of them are connected to the premises of tiny temples. these sacred groves comprise plant species that are endemic, rare and endangered. they are therefore natural nursery with rare, threatened and endemic plant species, many of which have vanished outside the groves from the region (colding and folke, 1997). local communities preserve and protect sacred groves because of their religious convictions and the related traditional rituals that run through several generations. they may consist of multi-species, multitier primary forests or a clump of trees, depending on the history of the vegetation (gokhale et al., 2011). according to hughes and chandran (1998), these groves are landscape segments comprising vegetation and other types of life and geographical characteristics that are delimited and protected by human communities, believing that maintaining them in a comparatively undisturbed state is an expression of human relationship with the divine or nature. such groves are often situated in biodiversityrich areas, ranging from a few trees to multi-acre forestland. adapting a plant to certain ecological circumstances determines a type of life; therefore, it is a significant feature of physiognomy that has been commonly used in vegetation assessment. it shows the macro and microclimate and human disturbances of a certain area (cain and castro, 1959). doi: https://doi.org/10.31357/jtfe.v10i1.4686 18 the word “biological spectrum” was suggested by raunkiaer (1934) to describe the distribution of life-form in a flora as well as the phytoclimate under which the prevailing life-forms developed.under this scheme, plant species can be divided into five primary groups, i.e., phanerophytes, chamaephytes, hemicryptophytes, cryptophytes and therophytes. the percentage of various life form classes put together is called as the biological spectrum. raunkiaer (1934) built a standard spectrum that could behave as a null model, compared to different spectra of life form. the standard spectrum of raunkiaer (1934) shows a phanerophytic community, and the deviation (from it) determines the habit's phytoclimate. the occurrence in separate areas of comparable biological spectra shows comparable climatic circumstances. thus, the differences between normal spectrum and biological spectrum life forms may point out which life form characterises the phytoclimate or vegetation. climatic types may be characterised by the prevailing plant life forms in the plant communities under a specific climatic regime (raunkiaer, 1934; cain, 1950; muller and ellenberg, 1974; saxena et al., 1982). the indian region's biological spectrum is linked to particular edaphic, altitude and climatic variables (meher-homji, 1964; rana et al., 2002; reddy et al., 2011; sen and bhakat, 2009, 2012; singh and gupta, 2015; sen, 2016, 2018; sen and bhakat, 2018, 2019a, b, c). studying life-form is therefore a significant component of the description of vegetation, ranking next to floristic structure (batalha and martins, 2004). therefore, the biological spectrum is helpful as an index of forest landscape health status. biological spectrum may set rules for a community's optimisation and eco-restoration when performed at regular intervals. life form may also be categorised using leaf size i.e., leptophylls, nanophyll, microphyll, notophyll, mesophyll, macrophyll and megaphyll. it has some justification for using a leaf size to characterise distinct kinds of vegetation based on percentages of the distinct leaf dimensions present. however, light intensity and soil conditions, especially nitrogen and phosphorus accessible; also have a significant impact on the size of the leaf even within the same genotype (cunningham et al., 1999). 2. materials and methods 2.1 study site a) the sacred grove the study was conducted in a forested sacred grove namely sbt on outer edge of a tribal dominated chhotopindara, ranijhor and dochakhuria villages along the south-western bank of a perennial rivulet palpala, under gidni block (latitude 22 o 26 / 00.09 // -22 o 26 / 01.48 // n and longitude 86 o 50 / 00.90 // -86 o 50 / 01.56 // e, average altitude 86.7 m asl) in jhargram district of west bengal, india (figure. 1, 2, 3). the grove houses a brick-made small temple and is spread over a 3.5 acre public land. the grove is located about 38 km southeast from district headquarters at jhargram town, located in the southern part of west bengal, india (figure. 1). it represents a 400-450-year-old relict forest patch consisting of evergreen, deciduous and semideciduous plants. after the eight days of annual paus sankranti (a ritual celebrated on the last day of the bengali month paus or middle of january) and every tuesday and saturday local people, both tribal and non-tribal of gidni and adjoining blocks, visit the grove and worship the deity. since the grove is an abode of deity, the entire area along with plants and other life forms is considered sacred. owing to this socio-cultural tag on the grove, local people do not cut or disturb the grove flora, thus strictly adhering to the taboos and ethics. sen and bhakat/ journal of tropical forestry and environment vol. 10 no. 01 (2020) 17-39 19 jhargram district covers an area of 3,037.64 km 2 and had a population of 1,136,548 in the 2011 census. 96.52% of the total population were rural and only 3.48% were urban population. 20.11% of the total population belonged to scheduled castes and 29.37% belonged to scheduled tribes. its population growth rate over the decade 2001-2011 was 10.9%. the literacy rate was 72% in 2011, where the male literacy rate was 81% and female at 64%. the sex ratio was 979 females per 1,000 males (anon, 2011). 2.2 field survey and data collection during the period from december 2012 to january 2019, the study area was carefully surveyed in various seasons to explore the botanical and social wealth. a short floristic study was conducted on the grounds of “spot identification”. samples of plants with flowers or fruits have been gathered for unknown plants. the samples were processed, maintained, poisoned and assembled on herbarium sheets using conventional and modern herbarium methods after collection (jain and rao, 1977). in the sacred grove, photographs were taken of some prevalent, locally rare, endemic and valuable plant species. herbarium sheets have been recognised by matching properly annotated materials available at vidyasagar university's herbarium. for identification purpose, different relevant catalogue (anderson, 1862), regional floras (hooker, 1872-1897; prain, 1903; haines, 1921-1925; bennet, 1979; sanyal, 1994), monographs (mitra, 1958), revisionary works (datta and majumdar, 1966) and other literature were consulted. the socio-cultural functions surrounding the grove were recorded through information collected by interviewing and cross-interviewing the local people. 2.3 analysis of vegetation in the systematic enumeration of the taxa; clade, order, family, species along with habit, lifespan, flowering and fruiting time, raunkiaer‟s life-form with sub-type, leaf spectra, iucn status (iucn, 2020) and distribution of the plants in the grove have been arranged according to angiosperm phylogeny group iv classification (chase et al., 2016) (table 1). all the species were categorised into various raunkiaer‟s life form categories depending on the position of regenerating parts or propagules in all the collected species. thus a biological spectrum was prepared for the grove that was subsequently compared with the raunkiaer‟s normal spectrum to determine the phytoclimate of the grove (raunkiaer, 1934; muller and ellenberg, 1974). the knowledge of leaf size helped us understand the physiological status of plants and the plant communities were useful in classifying the associations of plants. plants were divided into (a) leptophyll (<25 mm 2 ), (b) nanophyll (25-225 mm 2 ), (c) microphyll (225-2,025 figure 1. location of the study area. figure 2. google earth image showing sbt sacred. grove. figure 3. small temple in sbt sacred grove. 20 mm 2 ), (d) notophyll (2,025-4,500 mm 2 ), (e) mesophyll (4,500-18,225 mm 2 ), (f) macrophyll (18,225164,025 mm 2 ) and (g) megaphyll (>164,025 mm 2 ) (raunkiaer, 1934). 3. results and discussion 3.1 different plant taxa in the present study, a total of 307 species belonging to 249 genera distributed over 79 families under 36 orders (apg iv, 2016) were recorded from the sacred grove. the top two clades are rosids and asterids. more than 81% of the flora is represented by orders of eudicot and core eudicot, of which the major contributions in terms of descending species number (≥10 species) are from fabales 37 (12.05%), lamiales 36 (11.73%), gentianales 28 (9.12%), poales 28 (9.12%), malvales 20 (6.51%), asterales 17 (5.54%), malpighiales 17 (5.54%), myrtales 15 (4.89%), solanales 14 (4.56%), sapindales 13 (4.23%) and caryophyllales 12 (3.91%) (table 1, figure. 4). similar types of distribution of orders were highlighted by gnanasekaran et al., 2012; sen, 2016, 2018 and sen and bhakat, 2018, 2019a, b, c. figure 4. major contribution of orders (≥10 species) in the sbt. the fourteen well represented families in species (≥6 species), are: fabaceae 36 (11.73%), poaceae 20 (6.51%), malvaceae 19 (6.19%), apocynaceae 18 (5.86%), asteraceae 17 (5.54%), lamiaceae 15 (4.89%), acanthaceae 12 (3.91%), euphorbiaceae 9 (2.93%), rubiaceae 9 (2.93%), cyperaceae 8 (2.61%), solanaceae 8 (2.61%), amaranthaceae 6 (1.95%), combretaceae 6 (1.95%) and convolvulaceae 6 (1.95%) (table 1, figure. 5). cucurbitaceae, moraceae and phyllanthaceae comprised 5 (1.62%) species each. four families contained 4 (1.30%), eight families contained 3 (0.98%) and thirteen families covered 2 (0.65%) species. another 37 families each had only a single species (table 1). t o ta l n o . o f sp e c ie s dominant orders (≥10 species) figure 5. major contribution of families (≥6 species) in the sbt. total no. of the species n a m e o f th e f a m il ie s sen and bhakat/ journal of tropical forestry and environment vol. 10 no. 01 (2020) 17-39 21 same type dominant families of sacred groves in india were observed by rajendraprasad et al., 1998; ghildiyal et al., 2016; sen, 2016 etc. in the global context, such family dominance was shown by batalha and martins, 2004; badshah et al., 2016; chigani et al., 2017 etc. asteraceae, fabaceae and poaceae emerged as the common families in the investigated area. mendez (2005) also stated that the abundance of the same families in laguna (mendoza, argentina). the members of fabaceae and poaceae were dominant due to their distribution with wide ecological amplitude. 3.2 species diversity in different growth forms the present floristic study of the sacred grove showed that it harboured a total of 307 plant species [dicots 249 (81.11%) and monocots 58 (18.89%)] belonging to 249 genera [dicots 203 (81.53%) and monocots 46 (18.47%)] of 79 families [dicots 62 (78.48%) and monocots 17 (21.52%)] under 36 orders [dicots 27 (75%) and monocots 9 (25%)]. among these, 119 (38.76%) of the reported species were herbs followed by shrubs 63 (20.52%), trees 76 (24.76%) and climbers 49 (15.96%) respectively. amongst the total dicots 249 (81.11%) and monocots 58 (18.89%), herbs, shrubs, trees and climbers represented 79, 59, 70, 41 and 40, 4, 6, 8 species respectively, representing 25.73%, 19.22%, 22.80%, 13.36% and 13.03%, 1.30%, 1.95%, 2.61% of the total species (table 2, figure 6). figure 6. total angiosperm taxa. -50 0 50 100 150 200 250 300 orders families genera herbs species shrubs trees climber total t o ta l n o . o f sp e c ie s different angiosperm taxa 22 table 1: floristic list of sbt sacred grove. name of the species habit life-span fl. and fr. time raunkiaer‟s life-form sub-type leaf spectra iucn red list status piperales bercht. and j. presl aristolochiaceae juss. aristolochia indica l. c a jul.-jan. cr no ne magnoliales juss. ex bercht. and j. presl annonaceae juss. annona reticulata l. t p jul.-dec. ph n me ne annona squamosa l. t p mar.-sep. ph n me lc laurales juss. ex bercht. and j. presl lauraceae juss. litsea glutinosa (lour.) c. b. rob. t p apr.-sep. ph m ma lc independent lineage: unplaced to more inclusive clade alismatales r. br. ex bercht. and j. presl araceae juss. alocasia macrorrhizos (l.) g. don h p apr.-may cr me ne amorphophallus paeoniifolius (dennst.) nicolson h a jun.-dec. cr mg lc colocasia esculenta (l.) schott h a jul.-oct. cr mg lc scindapsus officinalis (roxb.) schott c p cr mg ne hydrocharitaceae juss. hydrilla verticillata (l. f.) royle h a nov.-mar. cr le lc dioscoreales mart. dioscoreaceae r. br. dioscorea alata l. c p aug.-dec. cr ma ne dioscorea bulbifera l. c p aug.-dec. cr ma ne dioscorea pentaphylla l. c p sep.-feb. cr me ne pandanales r. br. ex bercht. and j. presl pandanaceae r. br. pandanus odorifer (forssk.) kuntze s p jul.-may ph n ma lc liliales perleb colchicaceae dc. gloriosa superba l. c p jul.-sep. cr no lc smilacaceae vent. smilax ovalifolia roxb. ex d. don c p jun.-dec. ch me ne asparagales link orchidaceae juss. vanda tessellata (roxb.) hook. ex g. don h p apr.-jul. ph n no lc sen and bhakat/ journal of tropical forestry and environment vol. 10 no. 01 (2020) 17-39 23 hypoxidaceae r. br. name of the species habit life-span fl. and fr. time raunkiaer‟s life-form sub-type leaf spectra iucn red list status curculigo orchioides gaertn. h p aug.-oct. cr mi ne xanthorrhoeaceae aloe vera (l.) burm.f. h p dec.-feb. cr me ne amaryllidaceae j. st.-hil. crinum asiaticum l. h p aug.-oct. cr mg ne asparagaceae juss. agave americana l. s p sep.-mar. cr mg ne asparagus racemosus willd. c p aug.-dec. cr le ne yucca gloriosa l. s p nov.-jun. cr me ne arecales bromhead arecaceae bercht. and j. presl borassus flabellifer l. t p mar.-oct. ph mm mg en phoenix acaulis roxb. s p feb.-jun. ch me ne phoenix sylvestris (l.) roxb. t p feb.-jun. ph m me ne commelinales mirb. ex bercht. and j. presl commelinaceae mirb. commelina benghalensis l. h a aug.-nov. th mi lc murdannia nudiflora (l.) brenan h a jul.-nov. th na ne zingiberales griseb. costaceae nakai cheilocostus speciosus (j. koenig) c. d. specht h p jul.-sep. cr ma ne zingiberaceae martinov curcuma aromatica salisb. h p may-jun. cr ma ne kaempferia galanga l. h p may-jun. cr ma ne poales small cyperaceae juss. cyperus difformis l. h p jul.-nov. he le lc cyperus dubius rottb. h p sep.-dec. he le lc cyperus platystylis r. br. h p may-jun. he le ne cyperus rotundus l. h p sep.-dec. he le lc fimbristylis cymosa r. br. h p feb.-may he le lc fimbristylis dichotoma (l.) vahl h p aug.-oct. he le lc fimbristylis quinquangularis (vahl) kunth h p aug.-nov. he le lc rhynchospora colorata (l.) h. pfeiff. h p may-oct. he le ne poaceae barnhart aristida setacea retz. h p aug.-dec. he le ne 24 bambusa bambos (l.) voss t p jul.-feb. ph m me lc brachiaria reptans (l.) c. a. gardner and c. e. hubb. h a aug.-oct. he mi lc name of the species habit life-span fl. and fr. time raunkiaer‟s life-form sub-type leaf spectra iucn red list status chloris barbata (l.) sw. h p aug.-nov. he le ne chrysopogon aciculatus (retz.) trin. h p sep.-dec. he le ne chrysopogon zizanioides (l.) roberty h p jun.-oct. he le ne coix lacryma-jobi l. h a aug.-jan. he no ne cymbopogon citratus (dc.) stapf. h a oct.-dec. he le ne cynodon dactylon (l.) pers. h p all he le ne digitaria sanguinalis (l.) scop. h p mar.-jun. he le ne echinochloa crusgalli (l.) p. beauv. h a aug.-nov. he na lc echinochloa frumentacea link h a aug.-nov. he na lc eleusine indica (l.) gaertn. h p aug.-nov. he le lc eragrostis amabilis (l.) wight and am. h p aug.-feb. he le ne eragrostis ciliaris (l.) r. br. h p aug.-feb. he le ne imperata cylindrica (l.) raeusch. h p oct.-dec. he na lc paspalum scrobiculatum l. h p aug.-nov. he na lc pennisetum glaucum (l.) r. br. h p aug.-oct. he mi lc setaria glauca (l.) r. br. h p aug.-nov. he le ne sporobolus indicus (l.) r. br. h p aug.-nov. he na ne eudicots ranunculales juss. ex bercht. and j. presl papaveraceae juss. argemone mexicana l. h a dec.-apr. th ma ne menispermaceae juss. stephania japonica (thunb.) mier. c p jul.-dec. ph n me ne tinospora sinensis (lour.) merr. c p feb.-jun. ph n me ne core eudicots superrosids saxifragales bercht. and j. presl crassulaceae j. st. -hil. bryophyllum pinnatum (lam.) oken h p mar.-jun. ch ma ne rosids vitales juss. ex bercht. and j. presl vitaceae juss. ampelocissus latifolia (roxb.) planch. c p jun.sep. ph n me ne cayratia trifolia (l.) domin. c p aug.-dec. ph n no ne cissus quadrangularis l. c p jul.-jan. ph n no ne sen and bhakat/ journal of tropical forestry and environment vol. 10 no. 01 (2020) 17-39 25 leea asiatica (l.) ridsdale c p jul.-sep. ph n me ne zygophyllales link zygophyllaceae r. br. name of the species habit life-span fl. and fr. time raunkiaer‟s life-form sub-type leaf spectra iucn red list status tribulus terrestris l. c a feb.-sep. th na lc fabales bromhead fabaceae lindl. abrus precatorius l. c p aug.-mar. ph n na ne acacia pennata (l.) willd. t p feb.-oct ph m na lc acacia polyacantha willd. t p feb.-oct ph m na lc acacia rugata (lam.) fawc. and rendle t p feb.-oct ph m na ne acacia auriculiformis benth. t p feb.-oct. ph m me lc acacia nilotica (l.) delile t p jun.-sep. ph m na lc adenanthera pavonina l. t p mar.-jan. ph m no lc albizia lebbeck (l.) benth. t p mar.-feb. ph mm mi ne albizia saman (jacq.) merr. t p mar.-feb. ph mm me ne bauhinia vahlii wight and arn. c p apr.-feb. ph n mg ne bauhinia variegate l. t p feb.-jun. ph m me lc butea superba roxb. c p feb.-jul. ph m ma ne caesalpinia pulcherrima (l.) sw. t p mar.-sep. ph m mi lc caesalpinia bonduc (l.) roxb. c p aug.-apr. ph n mi lc caesalpinia globulorum bakh. f. and p. royen c p mar.-sep. ph n mi ne cajanus scarabaeoides (l.) thouars c a sep.-feb. ph n mi lc clitoria ternatea l. c a all ph n no ne codariocalyx motorius (houtt.) h. ohashi s a aug.-dec. ch na ne crotalaria pallida aiton s a aug.-jan. ch no ne crotalaria prostrata willd. h a aug.-jan. th no ne derris indica (lam.) bennet c p jul.-jan. ph n na ne flemingia strobilifera (l.) w. t. aiton h a feb.-sep. ch me ne indigofera tinctoria l. h b aug.-nov. th mi ne mimosa pudica l. h p jul.-nov. th na lc mimosa rubicaulis lam. s p jul.-nov. ch na ne mucuna pruriens (l.) dc. c a sep.-may ch le ne parkinsonia aculeate l. t p oct.-jun. ph n mi lc peltophorum pterocarpum (dc.) k. heyne t p mar.-jan. ph mm mi ne pongamia pinnata (l.) pierre t p apr.-feb. ph m me lc senna alata (l.) roxb. s a aug.-nov. ch ma lc senna occidentalis (l.) link s p aug.-dec. ch no ne 26 senna tora (l.) roxb. h a sep.-dec. th mi ne sesbania sesban (l.) merr. s p dec.-apr. ch ma lc tamarindus indica l. t p apr.-jan. ph mm na lc tephrosia purpurea (l.) pers. h p sep.-dec. th na lc name of the species habit life-span fl. and fr. time raunkiaer‟s life-form sub-type leaf spectra iucn red list status zornia gibbosa span. h a aug.-nov. th na ne polygalaceae hoffmanns. and link polygala arvensis willd. h a jul.-dec. th me ne rosales bercht. and j.presl rhamnaceae juss. ventilago denticulata willd. c p sep.-jun. ph n me ne ziziphus jujube mill. t p sep.-mar. ph m no lc ziziphus oenopolia (l.) mill. c p nov.-mar. ph n no lc ulmaceae mirb. holoptelea integrifolia planch t p jan.-jun. ph mm me ne moraceae gaudich. artocarpus heterophyllus lamk. t p jan.-aug. ph m ma ne ficus benghalensis l. t p mar.-sep. ph mm ma ne ficus religiosa l. t p jun.-aug. ph mm ma ne ficus racemose l. t p mar.-aug. ph m ma lc streblus asper lour. t p feb.-jun. ph n mi lc cucurbitales juss. ex bercht. and j. presl cucurbitaceae juss. cayaponia laciniosa (l.) c. jeffrey c a jun.-jan. ph n mi ne coccinia grandis (l.) voigt c p mar.-dec. ph n me ne momordica dioica roxb. ex willd. c a aug.-dec. ph n me ne trichosanthes cucumerina l c p aug.-dec. ph n me ne trichosanthes tricuspidata lour. c a apr.-sep. ph n me ne celastrales link celastraceae r. br. celastrus paniculatus willd. c p apr.-dec. ph n me ne oxalidales bercht. and j. presl oxalidaceae r.br. averrhoa carambola l. t p feb.-sep. ph n ma ne oxalis corniculata l. h a all th na ne malpighiales juss. ex bercht. and j. presl clusiaceae lindl. garcinia xanthochymus hook. f. ex t. anderson t p mar.-jan. ph m no ne sen and bhakat/ journal of tropical forestry and environment vol. 10 no. 01 (2020) 17-39 27 violaceae batsch hybanthus enneaspermus (l.) f. muell. h p jul.-nov. th na ne salicaceae mirb. flacourtia indica (burm. f.) merr. s p sep.-may. ch mi lc name of the species habit life-span fl. and fr. time raunkiaer‟s life-form sub-type leaf spectra iucn red list status euphorbiaceae juss. acalypha indica l. h a all th no ne croton bonplandianus baill. h p all th no ne euphorbia antiquorum l. t p jan.-apr. ph n le ne euphorbia hirta l. h a feb.-dec. th na ne euphorbia neriifolia l. s p oct.-feb. ch le ne jatropha curcas l. s p mar.-aug. ch ma ne jatropha gossypifolia l. s p mar.-aug. ch ma ne ricinus communis l. s p jan.-apr. ph n mg ne tragia involucrata l. c p mar.-jan. ph n me ne phyllanthaceae martinov antidesma acidum retz. t p jun.-dec. ph n me lc breynia vitis-idaea (burm. f.) c. e. c. fisch. s p apr.-dec. ph n mi lc bridelia retusa (l.) a. juss. t p mar.-dec. ph n me lc phyllanthus amarus schumach. and thonn. h a apr.-sep. th na ne phyllanthus virgatus g. forst. h a apr.-sep. th na ne myrtales juss. ex bercht. and j. presl combretaceae r. br. combretum album pers. c p nov.-may ph n me ne combretum decandrum jacq. c p nov.-may ph n me ne combretum indicum (l.) de filipps c p all ph n me ne terminalia arjuna (roxb. ex dc.) wight and arn. t p apr.-feb. ph mm ma ne terminalia bellirica (gaertn.) roxb. t p apr.-feb. ph mm ma ne terminalia tomentosa (roxb.) wight and arn. t p apr.-may ph mm ma ne lythraceae j.st.-hil. ammannia baccifera l. h a sep.-feb. th le lc lawsonia inermis l. s p oct.-dec. ph n na ne punica granatum l. s p mar.-oct. ph n na lc rotala densiflora (roth) koehne h a aug.-nov. th le lc onagraceae juss. ludwigia octovalvis (jacq.) p. h. raven h a sep.-jan. th mi lc myrtaceae juss. 28 eucalyptus tereticornis sm. t p mar.-jul. ph mm me ne psidium guajava l. t p apr.-oct. ph n me lc syzygium cumini (l.) skeels t p mar.-jul. ph mm me lc melastomataceae juss. melastoma malabathricum l. s p may-jan. ch me ne name of the species habit life-span fl. and fr. time raunkiaer‟s life-form sub-type leaf spectra iucn red list status sapindales juss. ex bercht. and j. presl anacardiaceae r. br. lannea coromandelica (houtt.) merr. t p feb.-jun. ph m mg ne mangifera indica l. t p feb.-jun. ph m ma dd semecarpus anacardium l. f. t p jul.-dec. ph m mg ne sapindaceae juss. cardiospermum halicacabum l. c a jul.-dec. ph n no ne sapindus emarginatus vahl t p dec.-may ph m me ne schleichera oleosa (lour.) merr. t p mar.-jul. ph mm ma lc rutaceae juss. aegle marmelos (l.) corrêa t p may-jul. ph m me ne glycosmis pentaphylla (retz.) dc. t p sep.-feb. ph n me lc limonia acidissima groff t p jan.-dec. ph m na ne murraya koenigii (l.) spreng. t p apr.-jun. ph n na ne simaroubaceae dc. ailanthus excelsa roxb. t p jan.-jun. ph mm ma ne meliaceae juss. azadirachta indica a. juss. t p mar.-jul. ph m no lc melia azedarach l. t p feb.-nov. ph m no lc malvales juss. ex bercht. and j. presl malvaceae juss. abelmoschus crinitus wall. s a mar.-sep. ch no ne abelmoschus moschatus medik. s a mar.-aug.. ch no ne abutilon indicum (l.) sweet s a jun.-dec. ch ma ne ambroma augusta l. f. s p jan.-mar. ph n ma ne azanza lampas (cav.) alef. s a sep.-dec. ch ma ne corchorus aestuans l. h a jul.-nov. th me ne gossypium arboreum l. s p aug.-feb. ch ma nt gossypium barbadense l. s p dec.-apr. ch ma lc grewia helicterifolia wall, ex g. don t p jun.-sep. ph n ma ne grewia asiatica l. t p jun.-aug. ph n me lc helicteres isora l. s p sep.-feb. ph n me ne hibiscus rosa-sinensis l. s p all ch me ne sen and bhakat/ journal of tropical forestry and environment vol. 10 no. 01 (2020) 17-39 29 hibiscus vitifolius l. s a oct.-feb. ch me ne pterospermum acerifolium (l.) willd. t p jan.-aug. ph mm ma ne sida acuta burm. f. s a aug.-dec. th no ne sida cordata (burm.f.) borss. waalk. h a aug.-feb. th no ne sida cordifolia l. s a aug.-dec. th no ne triumfetta rhomboidea jacq. s a sep.-jan. th me ne name of the species habit life-span fl. and fr. time raunkiaer‟s life-form sub-type leaf spectra iucn red list status urena sinuata l. s a sep.-dec. ch no ne bixaceae kunth bixa orellana l. t p oct.-mar. ph n me lc brassicales bromhead capparaceae juss. capparis zeylanica l. c p mar.-oct. ph m no ne crateva nurvala buch.-ham. t p mar.-jul. ph m me ne cleomaceae bercht. and j. presl cleome gynandra l. h a jul.-sep. th no ne cleome viscosa l. h a sep.-apr. th no ne superasterids santalales r. br. ex bercht. and j. presl santalaceae r. br. viscum cruciatum sieber ex boiss. s p jan.-jun. ph n le ne loranthaceae juss. loranthus cordifolius wall. s a jul.-nov. ph n no ne scurrula atropurpurea (blume) danser s a nov.-mar. ph n no ne caryophyllales juss. ex bercht. and j. presl droseraceae salisb. drosera burmanni vahl h a nov.-apr. th le lc amaranthaceae juss achyranthes aspera l. h a sep.-feb. th mi ne aerva lanata (l.) juss. h a nov.-jan. th le ne alternanthera sessilis (l.) r. br. ex dc. h a jul.-feb. th mi lc amaranthus spinosus l. h a all th na ne amaranthus viridis l. h a all th na ne celosia argentea l. h a sep.-feb. th na ne aizoaceae martinov trianthema portulaccastrum l. h a apr.-oct. th mi ne nyctaginaceae juss. boerhavia diffusa l. h a jun.-dec. th mi ne 30 portulacaceae juss. portulaca oleracea l. h a jun.-dec. th mi ne cactaceae juss. cereus pterogonus lam. s p jun.-jul. ch le ne opuntia stricta (haw.) haw. s p apr.-aug. ch le lc asterids name of the species habit life-span fl. and fr. time raunkiaer‟s life-form sub-type leaf spectra iucn red list status cornales link cornaceae bercht. and j. presl alangium salviifolium (l. f.) wangerin t p mar.-jul. ph n me ne ericales bercht. and j. presl lecythidaceae a. rich. careya arborea roxb. t p jan.-apr. ph m mg ne sapotaceae juss. madhuca longifolia var latifolia (roxb.) a. chev. t p mar.-jul. ph mm ma ne mimusops elengi l. t p apr.-sep. ph mm me lc ebenaceae gurke diospyros melanoxylon roxb. t p apr.-jul. ph mm ma ne gentianales juss. ex bercht. and j. presl rubiaceae juss. gardenia gummifera l. f. t p mar.-aug. ph n no lc gardenia resinifera roth s p feb.-jun. ph n no ne haldina cordifolia (roxb.) ridsdale t p jun.-dec. ph mm ma ne hedyotis neesiana arn. h a jun.-nov. th na ne meyna spinose roxb. ex link s p mar.-jun. ch me ne morinda citrifolia l. t p feb.-may ph n ma ne neolamarckia cadamba (roxb.) bosser t p jul.-nov. ph mm ma ne oldenlandia corymbosa l. h a aug.-feb. th le lc spermacoce articularis l. f. h a all th na ne loganiaceae r.br. ex mart. strychnos nux-vomica l. t p mar.-jan. ph mm me ne apocynaceae juss. alstonia scholaris (l.) r. br. t p nov.-aug. ph mm me lc calotropis gigantean (l.) dryand. s p mar.-feb. ch ma ne carissa spinarum a. dc. c p mar.-oct. ph n no ne cascabela thevetia (l.) lippold t p all ph n mi lc catharanthus roseus (l.) g. don. s p all th no ne sen and bhakat/ journal of tropical forestry and environment vol. 10 no. 01 (2020) 17-39 31 cryptolepis dubia (burm.f.) m.r.almeida c p apr.-mar. ph n no ne gymnema sylvestre (retz.) r.br. ex sm. c p apr.-mar. ph n mi ne hemidesmus indicus (l.) r. br. ex schult. c p aug.-jan. ph n mi ne holarrhena pubescens wall. ex g. don t p apr.-feb. ph n ma lc ichnocarpus frutescens (l.) w. t. aiton s p sep.-mar. ph n no ne marsdenia sylvestris (retz.) p. l. forst. c p apr.-mar. ph n mi ne nerium oleander (l.) s p jul.-apr. ph n no lc name of the species habit life-span fl. and fr. time raunkiaer‟s life-form sub-type leaf spectra iucn red list status pergularia daemia (forssk.) chiov. c p sep.-jan. ph n me ne plumeria rubra (l.) t p oct.-may ph m no lc rauvolfia serpentina (l.) benth. ex kurz s p mar.-dec. th me ne rauvolfia tetraphylla l. s p feb.-dec. ch no ne tylophora indica (burm. f.) merr. c a apr.-oct. ph n no ne vallaris solanacea (roth) kuntze c p apr.-jan. ph n me ne boraginales juss. ex bercht. and j. presl boraginaceae juss. heliotropium indicum l. h a oct.-jan. th no ne solanales juss. ex bercht. and j. presl convolvulaceae juss. cuscuta reflexa roxb. c p nov.-mar. ph n ap ne evolvulus alsinoides (l.) l. h a jul.-feb. th na ne ipomoea aquatica forssk. h p all th no lc ipomoea mauritiana jacq, c p aug.-dec. ph n ma ne jacquemontia paniculata (burm. f.) hallier f. t p sep.-jan. ph n mi ne rivea hypocrateriformis choisy c p aug.-oct. ph n no ne solanaceae juss. datura metel l. s p aug.-may ch ma ne datura stramonium l. s p jul.-oct. ch ma ne physalis minima l. h a aug.-dec. ch ma ne solanum americanum mill. h a dec.-jun. th ma ne solanum rudepannum dunal h a dec.-jun. th ma lc solanum surattense burm. f. h a aug.-dec. th ma ne solanum torvum sw. h p jul.-mar. ch ma ne solanum virginianum l. h a dec.-jun. th ma ne lamiales bromhead oleaceae hoffmanns. and link nyctanthes arbor-tristis l. t p sep.-jan. ch mi ne plantaginaceae juss. 32 bacopa monnieri (l.) pennell h a apr.-jan. th na lc limnophila indica (l.) druce h a sep.-jan. th na lc scoparia dulcis l. h a may-dec. th na ne martyniaceae horan. martynia annua l. h a aug.-dec. ch me ne acanthaceae juss. andrographis echioides (l.) nees h a jul.-oct. th no ne andrographis paniculata (burm. f.) nees h a sep.-apr. th no ne name of the species habit life-span fl. and fr. time raunkiaer‟s life-form sub-type leaf spectra iucn red list status barleria lupulina lindl. s p dec.-apr. ch mi ne barleria prionitis (l.) s p dec.-apr. ch mi ne dicliptera bupleuroides nees h a jun.-oct. th no ne ecbolium viride (forsk.) alston h p dec.-apr. ch mi ne hemigraphis hirta t. anders. h a aug.-nov. th mi ne hygrophila auriculata (schumach.) heine h a sep.-jan. th mi lc justicia adhatoda l. s p feb.-apr. ch me ne justicia gendarussa burm.f. s p feb.-apr. ch me ne ruellia tuberosa l. h a aug.-nov. th mi ne rungia pectinata (l.) nees h a all th mi ne bignoniaceae juss. tecoma stans (l.) juss. ex kunth t p nov.-mar. ph n me ne stereospermum chelonoides (l. f.) dc. t p aug.-feb. ph m me ne verbenaceae j. st. hil. lantana camara (l.) s p nov.-feb. ch no ne lippia javanica (burm. f.) spreng. s p sep.-apr. ch mi ne lamiaceae martinov anisochilus carnosus (l. f.) wall. s a sep.-jan. ch no ne anisomeles indica (l.) kuntze h a sep.-jan. ch mi ne clerodendrum infortunatum l. s p feb.-jul. ch ma ne hyptis suaveolens (l.) poit. s a sep.-jan. ch me ne leonotis nepetifolia (l.) r. br. s a apr.-jul. th me ne leonurus sibiricus l. s a sep.-feb. ch mi ne leucas cephalotes (roth) spreng. h a sep.-dec. th mi ne mentha longifolia (l.) l. s a apr.-jul. th mi lc ocimum americanum l. s p all ch na ne ocimum basilicum l. h p may-jul. ch na ne ocimum tenuiflorum l. s p aug.-jan. ch na ne plectranthus amboinicus (lour.) spreng. h a may-sep. th mi ne sen and bhakat/ journal of tropical forestry and environment vol. 10 no. 01 (2020) 17-39 33 premna mollissima roth t p may-jul. ph m no ne tectona grandis l. f. t p jul.-jan. ph mm mg ne vitex negundo l. t p mar.-jun. ph n mi lc asterales link asteraceae bercht. and j.presl ageratum conyzoides (l.) l. h a nov.-mar. th mi lc ayapana triplinervis (vahl) r. m. king and h. rob. h a aug.-dec. th mi ne name of the species habit life-span fl. and fr. time raunkiaer‟s life-form sub-type leaf spectra iucn red list status baccharoides anthelmintica (l.) moench h a sep.-mar. th me ne blumea lacera (burm.f.) dc. h a aug.-feb. th mi ne chromolaena odorata (l.) r. m. king and h. rob. s a mar.-sep. ch mi ne cyanthillium albicans (dc.) h. rob. h a aug.-mar. th mi ne cyanthillium cinereum (l.) h. rob. h a nov.-feb. th me ne eclipta prostrata (l.) l. h a all th mi lc elephantopus scaber l. h a sep.-jan. th no ne enydra fluctuans dc. h a dec.-mar. th mi lc grangea maderaspatana (l.) poir. h a dec.-may th le lc sonchus oleraceus (l.) l. h a sep.-jan. th na ne sphaeranthus senegalensis dc. h a nov.-apr. th le lc sphagneticola calendulacea (l.) pruski h a all th me ne synedrella nodiflora (l.) gaertn. h a sep.-jan. th no ne tridax procumbens (l.) l. h a all th na ne xanthium strumarium l. h a sep.-apr. th me ne apiales nakai apiaceae lindl. centella asiatica (l.) urb. h a jul.-jan. th no lc abbreviation in habit: c-climber; h-herb; s-shrub; t-tree in life-span: a-annual; b-biennial; p-perennial in flowering and fruiting time: jan.-january; feb.-february; mar.-march; apr.-april; jun.-june; jul.-july; aug.-august; sep.-september; oct.-october; nov.november; dec.-december; all-all season in raunkiaer’s life-form and sub-type: ch-chamaephytes; cr-cryptophytes; he-hemicryptophytes; m-mesophanerophyte; mm-megaphanerophytes; nnanophanerophytes; ph-phanerophytes; th-therophytes in leaf spectra: ap-aphyllous; le-leptophyll; na-nanophyll; mi-microphyll; no-notophyll; me-mesophyll; ma-macrophyll; mg-megaphyll in iucn red list status: dd-data deficient; lc-least concern; ne-not evaluated; vu-vulnerable; nt-near threatened 34 table 2: total angiospermic taxa. group orders families genera species herbs shrubs trees climber total dicots 27 62 203 79 59 70 41 249 monocots 9 17 46 40 4 6 8 58 total 36 79 249 119 63 76 49 307 3.3 life span in the sacred grove, 109 (35.50%) annual plants would go through their life cycle in one growing season. as many as 1 (0.33%) biennial plant whose life cycle spans two years. as many as 197 (64.17%) perennial plants that could survive most unfavorable conditions and stayed alive for more than two years (table 1). 3.4 life form and biological spectrum the biological spectrum shows that phanerophytes 128 (41.69%) was the dominant, followed by therophytes 81 (26.38%), chamaephytes 52 (16.95%), hemicryptophytes 27 (8.79%), and cryptophytes 19(6.19%). of the phanerophytes, nanophanerophytes 73 (23.78%) was dominant than mesophanerophytes 31 (10.10%) and megaphanerophytes 24 (7.82%) (table 3, figure 7). it reveals that therophytes, chamaephytes, and cryptophytes constituted the higher percentage 13.38%, 7.95% and 0.19% respectively than the normal spectrum exhibiting “thero-chamae-cryptophytic” phytoclimate. further, the number of hemicryptophytes (17.21%) and phanerophytes (4.31%) was comparatively smaller in percentage than the raunkiaer‟s normal spectrum. of the phanerophytes, nanophanerophytes (8.78%) and megaphanerophytes (4.82%) were somewhat larger and mesophanerophyte (17.9%) was a comparatively smaller value than the raunkiaer‟s normal spectrum (table 3, figure 7). this result was probably due to the local protection under certain taboos of the sacred grove. the dominant therophytes, chamaephytes, and cryptophytes altogether constituted 49.52% of the life forms proportion. therophytes showed the maximum divergence of the normal spectrum; other workers had also reported a similar phytoclimatic association for different tracks of vegetation (misra et al., 1979; saxena et al., 1982; rajendraprasad et al., 1998; sen, 2018). the dominance of therophytes (81 species, 26.38%) indicates that the investigated area was under mild biotic pressure (sher et al., 2014). many plant species were decreasing in the area. it would be the moral and ethical duty of the local people to protect the plant resources. table 3: biological spectrum (% of all life forms) of study site and its comparison with raunkiaer‟s normal spectrum. life forms total no. of species biological spectrum (%) of the study site raunkiaer‟s normal spectrum (%) deviation=(raunkiaer‟s normal spectrum biological spectrum) phanerophytes (ph) 128 41.69 46.00 -4.31 megaphanerophytes (mm) 24 7.82 3.00 4.82 mesophanerophytes (m) 31 10.10 28.00 -17.90 nanophanerophytes (n) 73 23.78 15.00 8.78 chamaephytes (ch) 52 16.95 9.00 7.95 hemicryptophytes (he) 27 8.79 26.00 -17.21 cryptophytes (cr) 19 6.19 6.00 0.19 therophytes (th) 81 26.38 13.00 13.38 total 307 100.00 100.00 sen and bhakat/ journal of tropical forestry and environment vol. 10 no. 01 (2020) 17-39 35 figure 7. comparison of biological spectrum with raunkiaer‟s normal spectrum. 3.5 leaf size spectra the overall leaf size spectra showed that there were leptophyll 34 (11.11%), nanophyll 42 (13.73%), microphyll 50 (16.34%), notophyll 52 (16.99%), mesophyll 67 (21.90%), macrophyll 49 (16.01%) and megaphyll 12 (3.92%). cuscuta reflexa is only aphyllous species. as regards the leaf size spectra, mesophyll was found to be high followed by notophyll, microphyll, macrophyll, nanophyll, leptophyll, and megaphyll (table 1, 4). in case of leaf spectra, the presence of leptophyll 19 (6.21%), nanophyll 21 ( 6.86%), microphyll 22 (7.19%), notophyll 24 (7.84%), mesophyll 43 (14.05%), macrophyll 24 (7.84%) and megaphyll 7 (2.29%) have the maximum in comparison to hemicryptophytes, therophytes, therophytes, phanerophytes, phanerophytes, phanerophytes and phanerophytes respectively (table 4). cyperaceae 8 (2.61%), poaceae 5 (1.63%), fabaceae 9 (2.93%), apocynaceae 8 (2.61%), malvaceae 6 (1.95%), solanaceae 8 (2.61%) and araceae 3 (0.98%) were dominant families of leptophyll, nanophyll, microphyll, notophyll, mesophyll, macrophyll and megaphyll respectively (table 4, figure 8). this result was also similar to other tropical forests in asia (bohman, 2004; gillison, 2018). table 4: life-form analysis with different leaf size. abbreviation in raunkiaer’s life-form: ch-chamaephytes; cr-cryptophytes; he-hemicryptophytes; m-mesophanerophyte; mmmegaphanerophytes; n-nanophanerophytes; ph-phanerophytes; th-therophytes raunkiaer‟s life form leaf spectra total ap le na mi no me ma mg ph 1 2 11 16 24 43 24 7 128 mm 1 2 7 12 2 24 m 5 1 8 9 5 3 31 n 1 2 5 13 16 27 7 2 73 ch 4 5 9 8 11 15 52 he 19 5 2 1 27 cr 2 1 2 4 5 5 19 th 7 21 22 17 9 5 81 total 1 34 42 50 52 67 49 12 307 0 10 20 30 40 50 60 ph ch he cr th o f p la n t sp e c ie s% raunkiaer's life form biological spectrum (%) of the study site raunkiaer‟s normal spectrum (%) 36 in leaf spectra: ap-aphyllous; le-leptophyll; na-nanophyll; mi-microphyll; no-notophyll; me-mesophyll; mamacrophyll; mg-megaphyll figure. 8. analysis of life form with different leaf size. 3.6 conservation status and iucn categories among these 307 plant species, 220 plants have not been evaluated still now. there were 85 least concerned (lc), 1 data deficient (dd), 1 near threatened (nt) species according to the iucn (iucn, 2020) (table 1). based on the above-mentioned phytosociological analysis with ecological information on iucn red listed plants, it is revealed that plants are still present and regenerate in the sacred grove but locally disappear in highly disturbed areas. this study would highlight the status and distribution of the species in the study area, the ecological characteristics necessary for their survival, and the threats to some of the species identified by following the iucn (2020) criteria. it is because iucn red list applications are a global plant diversity barometer (brummitt et al., 2008). various factors caused the increase in numbers of threatened species in the area. grasing was a major cause which led to the destruction of seedlings. the most critical factor that caused the decline of the endemic useful species was human activity, such as pilgrimage, dying of the plant and land use change. 4. conclusion the current study indicates the option of using raunkiaer's strategy to ascertain the notable differences between the populations of angiosperm plants in a forested landscape or biome and their associations, the part of species in the percentage of floristic life-forms that resulted by the existing ecological parameters and environmental gradients. life-form analysis provides a clear image of the sacred grove's biological spectrum. in the present study therophytes, chamaephytes and cryptophyte share the importance depicting the “thero-chamae-cryptophytic” phytoclimate. it may also be noted that the information acquired from this study will in future serve as a database of life forms for research of change detection and tenacity of bioclimate or phytoclimate (raju et al., 2014). comparing and contrasting the neighboring natural strands pattern along the environmental gradients will also be useful, revealing more than the mere forest covers in the ecosystem data; suggesting that biotic variables play a significant part in shaping a landscape's vegetation by guiding succession. this shows the impact in the 0 10 20 30 40 50 60 70 80 ap leaf spectra le na mi no me ma mg r a u n k ia e r' s li fe f o rm leaf spectra ph ch he cr th sen and bhakat/ journal of tropical forestry and environment vol. 10 no. 01 (2020) 17-39 37 sacred grove of anthropogenic disturbances that favor the development of more therophytes. further disruption to the current sacred grove can therefore promote future changes in its current phytoclimate. acknowledgement the authors are indebted to the informants and local tribal communities for cooperating and sharing their knowledge. without their contribution, this study would have been impossible. references anderson, t., 1862. catalogue of plants indigenous in the neighbourhood of calcutta with directions for examination and preservation of plants, calcutta, india. anon, 2011. district human development report, paschim medinipur, government of west bengal, development and planning department, 306. badshah, l., hussain, f. and sher, z., 2016. floristic inventory, eco-logical characteristics and biological spectrum of plants of parachinar, kurram agency, pakistan. pakistan journal of botany, 48:1547-1558. batalha, m.a. and martins, f.r., 2004. floristic, frequency, and vegetation life-form spectra of a cerrado site. brazilian journal of biology, 64:201-209. bennet, s.s.r., 1979. flora of howrah district, dehradun, india, international book distributors, 406. berkes, f., 2009. community conserved areas: policy issues in historic and contemporary context. conservation letters, 2:20-25. bohman k., 2004. functional and morphological diversity of trees in different land use types along a rainforest margin in sulawesi. [ph.d. thesis] indonesia, gottingen, university of gottingen. brummitt, n., bachman, s.p. and moat, j., 2008. applications of the iucn red list: towards a global barometer for plant diversity. endanger species research, 6:127-135. cain, s.a. and castro, g.d.o., 1959. manual of vegetation analysis, new york, usa, harper and brothers, 325. cain, s.a., 1950. life-form and phytoclimates. botanical review, 16:1-32. chase, m.w., christenhusz, m.j.m., fay, m.f., byng, j.w., judd, w.s., soltis, d.e., mabberley, d.j., sennikov, a.n., soltis, p.s. and stevens p.f., 2016. an update of the angiosperm phylogeny group classification for the orders and families of flowering plants: apg iv. botanical journal of linnaean society, 181:1-20. chigani, h.k., javadi, s.a., zahedi-amiri, g., khajeddin, s.j. and jafari, m., 2017. vegetation composition differentiation and species-environment relationships in the northern part of isfahan province. land degradation and development, 9:161-175. colding, j. and folke, c., 1997. the relations among threatened species, their protection, and taboos. conservation ecology, 1:6. colding, j. and folke, c., 2001. social taboos: “invisible” systems of local resource management and biological conservation. ecological applications, 11:584-600. cunningham, s.a., summerhayes, b. and westoby, m., 1999. evolutionary divergences in leaf structure and chemistry, comparing rainfall and soil nutrient gradients. ecological monographs, 69:569588. datta, s.c. and majumdar, n.c., 1966. flora of calcutta and vicinity. bulletin of botanical society of bengal, 20:16-120. ghildiyal, j.c., barthwal, n. and khantwal, a., 2016. life-forms and biological spectrum of deeva ka daanda a sacred grove in garhwal himalaya. indian forester, 142:167-178. gillison, a.n., 2018. latitudinal variation in plant functional types. in: geographical changes in vegetation and plant functional types, springer, cham, pp. 21-57. 38 gnanasekaran, g., nehru, p. and narasimhan, d., 2012. angiosperms of sendirakillai sacred grove (ssg), cuddalore district, tamil nadu, india. check list, 8:113-129. gokhale, y., pala, n.a., negi, a.k., bhat, j.a. and todaria, n.p., 2011. sacred landscapes as repositories of biodiversity: a case study from the hariyali devi sacred landscape, uttarakhand. international journal of conservation science, 2:37-44. haines, h.h., 1921-1925. the botany of bihar and orissa, vol 1-6 (reprint 1961), calcutta, india, botanical survey of india. hooker, j.d., 1872-1897. the flora of british india, vols. 1-7 (repr. 1973), dehra dun, india, bishen singh mahendra pal singh. hughes, j.d. and chandran, m.d.s., 1998. sacred groves around the earth: an overview. in: ramakrishnan, p.s., saxena, k.g., chandrashekara, u.m. (eds.), conserving the sacred for biodiversity management. oxford and ibh publ. co. pvt. ltd., new delhi, india, pp. 69-86. iucn, 2020. the iucn red list of threatened species. version 2020-1, https://www.iucnredlist.org. accessed 29 june 2020. jain s.k. and rao, r.r., 1977. a handbook of field and herbarium methods, today and tomorrow‟s printers and publishers, new delhi, india, 157. meher-homji, v.m., 1964. life forms and biological spectra as epharmonic criteria of aridity and humidity in tropics. journal of indian botanical society, 43:424-430. mendez, e., 2005. the vegetation of the laguna de llancanelo provincial reserve (mendiza, argentina). candollea, 60:123-148. misra, m.p., mishra, p.n. and pandey, b.n., 1979. an ecological account of the vegetation of brahmyoni hills (gaya). proceedings of the indian science congress, 3:108-109. mitra j.n., 1958. flowering plants of eastern india, vol. 01. monocotyledons, the world press private ltd., calcutta, 388. muller d. and ellenberg, h., 1974. aims and methods of vegetation ecology, john wiley and sons, new york, usa, p. 547. prain d., 1903. bengal plants, vol. 01 and 02, botanical survey of india, calcutta, india, p. 670. rajendraprasad, m., krishnan, p.n. and pushpangadan, p., 1998. the life form spectrum of sacred grove and a functional tool to analyse the vegetation. tropical ecology, 39:211-217. raju, v.s., krishna, p.g. and suthari, s., 2014. environmental assessment of climate of a habitat through floristic life-form spectra, a case study of warangal north forest division, telangana, india. journal of natural sciences, 2:77-93. rana, t.s., datt, b. and rao, r.r., 2002. life forms and biological spectrum of the flora of tons valley, garhwal himalaya (uttaranchal), india. taiwania, 47:164-169. raunkiaer c., 1934. the life forms of plants and statistical plant geography, clarendon press, oxford, p. 632. reddy, s.c., krishna, h.p., meena, s.l., bhardwaj, r. and sharma, k.c., 2011. composition of life forms and biological spectrum along climatic gradient in rajasthan, india. international journal of environmental science, 7:1632-1639. sanyal, m.n., 1994. flora of bankura district, bishen singh mahendra pal singh, dehra dun, india, p. 555. saxena, a.k., pandey, p. and singh, j.s., 1982. biological spectrum and other structural functional attributes of the vegetation of kumaun himalaya. plant ecology, 49:111-119. sen, u.k. and bhakat, r.k., 2009. ecological role of sacred groves in plant conservation. effects of environmental toxicology on human health, national environmental science academy, new delhi, india, pp. 211-219. sen and bhakat/ journal of tropical forestry and environment vol. 10 no. 01 (2020) 17-39 39 sen, u.k. and bhakat, r.k., 2012. sacred grove and plant conservation: an insight from taxonomy and ecology. in: maiti, g.g., mukherjee, s.k. (eds.), mutidisciplinary approaches in angiosperm systamatics. department of botany, university of kalyani, west bengal, india, pp. 410-421. sen, u.k. and bhakat, r.k., 2018. in situ conservation of a sacred grove in west midnapore district, west bengal, india: an integrated socio-ecological approach. journal of economic and taxonomic botany, 42:49-64. sen, u.k. and bhakat, r.k., 2019a. floristic and phytoclimatic study of a sacred grove vegetation of west midnapore district, west bengal, india. journal of tropical life science, 9:119-138. sen, u.k. and bhakat, r.k., 2019b. assessment of the floristic composition, biological spectrum, leaf size spectra and traditional conservation management of a sacred grove in west midnapore district, west bengal, india. indian forester, 145:156-171. sen, u.k. and bhakat, r.k., 2019c. floristic composition, biological spectrum and conservation status of a sacred grove from jhargram district, west bengal, india. indian journal of forestry, 42:161172. sen, u.k., 2018. assessing the social, ecological and economic impact on conservation activities within human-modified landscapes: a case study in jhargram district of west bengal, india. international journal of conservation science, 9:319-336. sen. u.k., 2016. botanical and socio-cultural studies on some sacred groves of west midnapore district, west bengal, ph.d. thesis, midnapore, india, vidyasagar university, p. 321. sher, z., hussain, f. and badshah, l., 2014. biodiversity and ecological characterization of the flora of gadoon rangeland, district swabi, khyber pukhtunkhwa, pakistan. iranian journal of botany, 20:96-108. singh, r.i. and gupta, a., 2015. life-form classification and biological spectrum of amambilok sacred grove, andro, manipur in northeast india. pleione, 9:356-364. suraj et al. /journal of tropical forestry and environment vol. 9, no. 01 (2019) 7-18 7 variation in rooting pattern of leucaena leucocephala in relation to propagation system and stock mother plants suraj p.g.1, suresh m.2, ranjeeth babu p.1, varghese m.1* 1itc life sciences and technology centre (lstc), itc ltd, bengaluru 560 058, india 2itc pspd unit, itc ltd, sarapaka, bhadrachalam 507 128, india date received: 26-12-2018 date accepted: 20-04-2019 abstract lateral shoot cuttings are used for multiplication of leucaena leucocephala clones to control lodging in pulpwood plantations. variability in rooting pattern was evaluated in lateral cuttings from four types of mother plants (a) sand beds in shade house (sh), (b) sand beds with overhead shade, (c) open sand beds and (d) open field hedges (cma) in a commercial leucaena clone. rooting rate of sh cuttings varied significantly with propagation conditions across two mist chambers (87% in mc 1 versus 68% in mc 2). rooting pattern also differed with 77% cuttings in mc 1 having long root zone (>2.5 cm length from stem base) compared to only 10% plants in mc 2. application of rooting hormone (iba 5000 ppm) increased number of roots by 46% and root zone length by 39% in sh cuttings. rooting rate did not vary between winter and summer season. lateral cuttings from open sand bed and cma had comparatively thicker stem with anatomical configuration of larger pith region, large diameter vessels in low frequency and sclerenchyma bundles, compared to mother plants raised in shade (a and b). rooting rate was high (83-87%) in covered sand beds (a and b) compared to those (c and d) in open sunlight (43-68%). majority of cuttings from open sand bed (85%) and cma (93%) had short root zone (<2.5 cm length) compared to covered sand beds (30%). clonal propagules with good root system can be produced from leucaena cuttings when mother plants are maintained in shade and provided suitable propagation conditions. key words: vegetative propagation, clonal forestry, root system, stem anatomy, rooting hormone 1. introduction the tall variety k636 of leucaena leucocephala is widely planted for pulpwood in peninsular india. seed harvested from felled trees is traditionally used for planting which has high variability whereas clonal plantations can give at least 50% higher wood yield. clonal forestry in leucaena was hampered by low multiplication rate, poor root architecture and lodging in plantations. propagation methods were developed (victorio et al., 1998; dick et al., 1999) to capture traits of leucaena clones like tolerance to soil ph and psyllids. leucaena improvement focussed on enhancing biomass production (karim et al., 1991) for fodder whereas good root system is essential to support higher wood volume in clones for pulpwood production, compared to seed origin plantations. application of rooting hormone and selection of juvenile cuttings from suitable stem positions were found to be critical for good rooting in leucaena clones and hybrids (shi and brewbaker, 2006). a propagation technique was recently developed using lateral shoots from stock mother plants, maintained in sand beds, that give more than 80% rooting compared to conventionally used nodal stem cuttings (suraj and varghese, 2019). this propagation method was successfully implemented for large scale supply of clones to farmers for enhancing wood yield in plantations. *correspondence: mohan.varghese@itc.in; mvarghese1@rediffmail.com tel: +91 9164753961 issn 2235-9370 print/issn 2235-9362 online ©2019 university of sri jayewardenepura doi: https://doi.org/10.31357/jtfe.v9i1.3945 mailto:mohan.varghese@itc.in 8 vegetative propagation methods in forest trees evolved from traditionally used coppice shoots of clonal multiplication areas (cma) in open field, to clonal hedges maintained in sand beds. clonal hedges gave several advantages like higher productivity and year round supply of cuttings, due to better nourishment and controlled environmental conditions (de assis et al., 2004). introduction of minicutting technology paved the way for intensive management of stock mother plants for improved rooting features in clonal propagules of eucalyptus (de assis, 2011). minicutting technique has been employed in tree species like neem and teak (gehlot et al., 2014; badilla et al., 2016) with some modifications to suit the requirement of each species. in leucaena, nodal cuttings from cmas in open field, and minicuttings from intensively managed mother plants did not give similar success as in eucalypts due to specific characteristics of stem and turgor based responses in leaflets of mimosaceae (visnovitz et al., 2007). lateral shoots produced by modification of shoot orientation in stock mother plants gave encouraging results compared to apical and nodal stem cuttings in leucaena (suraj and varghese, 2019). management practice of stock mother plants can change the abiotic environment that influence root architecture in cuttings of the same genotype (bellini et al., 2014), and hence play a crucial role in determining the quality of cuttings produced. maturation in mother plants is usually associated with several changes in physiology and anatomical configuration of the stem, which influence juvenility and rooting ability of cuttings (leakey, 2004). environmental conditions of mother plants can influence lignification of cuttings that impact the endogenous hormone levels, and response of cutting to exogenous application of growth hormones (ford et al., 2001). temperature and humidity conditions of propagation chamber can also play a significant role in determining the root system of cuttings (cunha et al., 2009). this paper aims to evaluate the role of propagation system, and type of stock mother plant on rooting pattern in clonal leucaena plants, to reduce lodging in plantations. 2. methodology 2.1 the study area and details of experiments based on management practice, four kinds of stock mother plants of a commercially planted l. leucocephala clone were used for the study: (a) sand beds in covered shade house (sh), (b) sand beds provided with shade of one layer of agro shade net (c) open sand beds receiving direct sunlight, and (d) cma-mother plants planted in open field. the study was conducted during the period november 2017may 2018 in the commercial nursery of paperboards and specialty papers division (pspd), itc ltd. located at bhadrachalam (17°40/ n latitude and 81° e longitude) in telangana state in india. mother plants in sand beds and cma were pruned to 15 cm height in november 2017 for production of lateral shoots that emanate from the dormant lower buds at 30-45 degrees angle to the main stem (suraj and varghese, 2019). lateral shoots with apical bud were harvested after repeated pruning to ensure that shoots emerged at an angle to main stem. the nursery site has a tropical humid climate with mean annual temperature of 35° c, maximum temperature of 49° c during summer (april-june), minimum temperature of 10° c during winter (december-january), mean relative humidity of 70-80% and annual rainfall of 1,100 cm. the mother plants were provided nourishment (suraj and varghese, 2019) through controlled drip irrigation system. lateral shoot cuttings of 25-30 cm length were harvested from each type of mother plant and planted in rooting medium (vermiculite-coirpith in 2:1 ratio) in 93cc hycotrays of 40 cells after dipping the base of cutting in iba (5,000 ppm). the cuttings were subjected to misting for 20 days in mist chamber (holding capacity of 300,000 cuttings) where temperature (35-37° c) and relative humidity (8085%) were controlled using sensors and cooling fans. two mist chambers were used for the study-mc 1 (with fine misting) and mc 2 (coarse misting). misting of one-minute duration was given from 9:30 am to 5:30 pm at 30 minutes interval. light transmission into the chamber was controlled by a shade net provided below the polythene cover. suraj et al. /journal of tropical forestry and environment vol. 9, no. 01 (2019) 7-18 9 experiments were conducted to evaluate the following. (a) impact of hormone (iba 5000 ppm) treatment on root traits (b) variation in root traits across two mist chambers (holding capacity of 300,000 cuttings each) (c) impact of type of mother plant on rooting features of lateral shoot cuttings (d) anatomical configuration of lateral shoot cuttings from different types of mother plants experiment (a) was conducted from december 2017-january 2018, and (b), (c) and (d) were conducted during the period april-may, 2018. for experiments (a), (b) and (c) 2,000 cuttings each (10 trays of 40 plants each ×5 replications) were used and for (d), transverse sections were taken from the base of 15 cuttings of each category of mother plant. nursery protocol developed for leucaena clones (suraj and varghese, 2019) was followed. 2.2 evaluation of cuttings and rooting pattern mother plants were established in sand beds at a spacing of 20×15 cm whereas in field cma the mother plant spacing was 2.7 m×0.70 m. diameter and angle of emergence of lateral shoot from main stem were measured in 120 cuttings (40 cuttings each in 3 replications) per category of mother plant. the length of the cutting was fixed as 25-30 cm based on inference from a previous study (suraj and varghese, 2019). length of lateral shoot cuttings from cma ranged from 20-30 cm. diameter at the base of stem cutting was measured using a digital vernier calliper. each cutting had about 2-3 leaves trimmed to half the size. transverse sections (20-25μm) were taken from 15 cuttings of each category (5×3 replications) using a sledge microtome (leica sm2000r) after fixing samples in faa (formaldehyde-acetic acidethanol). sections were stained with safranin (0.5%) and passed through ethanol series and xylene. anatomical parameters were recorded using a leica (dm1000) light microscope and image analysis software leica qwin plus (v.3.5.0). for estimating rooting rate 2,000 cuttings (10 trays of 40 plants each ×5 replications) of each category of mother plant were evaluated by observing root emergence from the base of the hycotray after 20 days in mist chamber and 10 days hardening in shade house. root traits like number of roots, root distribution (scale of 1-5 based on spread of roots around the stem) and rooting pattern (length of root zone from base of cutting) were estimated by carefully removing the growth medium in 120 rooted cuttings (1 tray of 40 cuttings ×3 replications) of each category after 20 days in mist chamber. for evaluating rooting pattern, cuttings were classified into six groups based on length of root zone: group 1 (0.5-1.5 cm), group 2 (1.6-2.5 cm), group 3 (2.6-3.5 cm), group 4 (3.6-4.5 cm), group 5 (4.6-5.5 cm) and group 6 (>5.6 cm). root traits were also estimated in 120 five month old seedlings of variety k636. 2.3 experimental design and data analysis as misting conditions of two mist chambers (mc 1 and mc 2) were different, rooting efficiency of each chamber was evaluated using lateral cuttings from sand beds of covered shade house (sh). all the other studies on root traits were conducted simultaneously in mc 1. data were recorded from the following studies using randomised complete block design and analysed using one-way analysis of variance (anova). (a) rooting pattern of sh sand bed cuttings, with and without iba treatment in mc 1 (b) root traits of cuttings from sh sand bed across two mist chambers (mc 1 and mc 2) (c) specifics and rooting of cuttings from four types of mother plants in mc 1 (d) anatomical traits of cuttings from four mother plant sources. 10 mean values were compared by tukey hsd test when significant differences (p<0.05) were obtained in anova. all percentage data were subjected to arcsine transformation (√x/100) and count data transformed using formula √x+1 (snedecor and cochran, 1980). the statistical package r (r core team, 2013) was used for data analysis and the tukey hsd test was performed with the package=“agricolae” (de mendiburu, 2014). cuttings from different mother plant sources were classified according to the proportion of roots in each category based on length of root zone. 3. results 3.1 impact of exogenous hormone application and season on root traits iba treated sh cuttings had significantly higher rooting rate and better root distribution than control. rooting pattern also showed significant difference, with untreated cuttings having 40% lower mean root zone length and greater proportion (70%) of cuttings being in the lower root zone category (less than 2.5 cm length) compared to those treated with iba (table 1). rooting rate of iba treated sh cuttings (mc 1) did not differ much between summer (87.1%) and winter season (88.6%). root distribution and the number of roots (21-22) were also more or less at par when multiplied in both seasons (tables 1 and 2). there was slight difference in rooting pattern as cuttings rooted in summer had about 13% longer root zone than that in winter season. table 1: impact of iba treatment on root traits of lateral shoots from sand bed (sh) (after 20 days in mist chamber and 10 days in hardening chamber, n=2,000 each). no. treatment root distribution root zone length (cm) proportion of roots (%) < 2.5 cm root zone no. of roots rooting (%) 1 iba 5,000 ppm 4.9 a 2.76 a 57.1 21.05a 88.6 a 2 no hormone 4.3 b 1.97 b 70.0 14.40b 81.4 b significance source ** ** ** ** ** significant at p<0.01, mean values of each trait with same letter do not vary significantly (p<0.05). 3.2 specifics and root traits of lateral cuttings and seedlings basal diameter recorded from lateral shoot cuttings (25-30 cm length) in different types of mother plants revealed that cuttings from sand beds were at least 18% thinner than those from field cma (table 2). among sand beds, cuttings grown under shade and covered shade house (sh) had atleast 14% lower diameter than sand beds laid out in open. lateral shoots from sand beds in shade and sh had more horizontal orientation of about 10 degrees’ higher angle than those of cma and open sand beds. rooting was significantly higher in cuttings from sand beds in sh (87%) and under shade (82%) than open sand beds (68%) and field cma (43%). root distribution was also 53% better in covered sand bed cuttings than in open sand beds and field cma. cuttings from sh and shaded sand beds had significantly more roots (22-24) than open sand beds and cma (19 and 14 roots respectively). root zone length was at least 73% higher in cuttings from sh (3.11 cm) and sand beds with shade (3.14 cm), compared to open sand beds (1.79 cm), and cma (1.44 cm). seedlings had significantly higher number of roots (46) and longer root zone (6.7 cm) with good distribution (on par with sh cuttings). suraj et al. /journal of tropical forestry and environment vol. 9, no. 01 (2019) 7-18 11 table 2: details of lateral shoot cuttings from different mother plant sources and root traits with iba treatment after 20 days in mist chamber. no. source mist chamber spacing (cm) cutting diameter (mm) root distribution root zone (cm) shoot angle (deg) no. of roots rooting (%) 1 sand bed-sh mc 1 20×15 2.58 a 5.0 a 3.11 b 45 a 22.0 bc 87.1 a sand bed-sh mc 2 20×15 2.58 a 4.8 a 1.67 c 45 a 15.6 de 68.2 b 2 sand bed-shade mc 1 20×15 2.67 a 5.0 a 3.14 b 48 a 24.0 b 82.6 a 3 sand bed-open mc 1 20×15 3.11 b 3.6 b 1.79 c 35 b 19.2 cd 68.0 b 4 cma mc 1 270×70 3.25 b 3.4 b 1.44 c 35 b 14.7 e 43.3 c 5 seedlings 5.0 a 6.67 a 46.3 a significance source *** *** *** *** *** *** *** significant at p<0.001, mean values of each trait with same letter do not vary significantly (p<0.05). sh-shade house, mist chambers-mc 1 and mc 2. 3.3 variation in rooting pattern with propagation system and mother plant propagation system had a significant impact on rooting, as rooting efficiency of mc 1 (87%) was significantly higher than that of mc 2 (68%) for the same set of sh cuttings (table 2). along with the difference in rooting rate, there was also a drastic difference in rooting pattern as 90% cuttings in mc 2 had root zone length of less than 2.5 cm whereas 77% of the rooted cuttings in mc 1 had root zone of more than 2.6 cm length (figure 1). figure 1: rooting pattern of lateral cuttings (from sand beds in shade house) across two mist chambers (mc 1 and mc 2). source of mother plant also had a big impact on rooting pattern (figure 2). cuttings from sh (78%) and covered sand beds (69%) had large proportion of plants with more than 2.6 cm long root zone. majority of rooted cuttings from open sand beds (85%) and cma (93%) had less than 2.5 cm root zone. sh cuttings rooted in mc 2 had about 46% lower root zone than those in mc 1, on par with that of open sand beds and cma cuttings in mc 1. root distribution was however more or less similar in sh cuttings rooted in both mist chambers (table 2). cuttings from both types of covered sand beds (sh and shaded) 12 had more or less similar root system with higher root zone length and number of roots compared to cma but only half the number of roots and root zone as that of seedlings (figure 3). figure 2: rooting pattern of lateral cuttings from mother plants maintained in shade house, sand beds (open and with shade) and open field (cma). figure 3: root distribution in lateral cuttings treated with iba 5000 ppm from (a) sand beds in shade house (b) sand beds in shade (c) field cma and (d) seedlings [note the low root zone length in short cutting (c) from cma]. 3.4 variation in anatomical structure of cuttings anatomical configuration of cuttings differed significantly based on source of mother plant. cuttings from covered sand beds had different structure from that of open sand beds and cma. transverse stem sections revealed that cuttings from covered sand beds had at least 19% lower pith region suraj et al. /journal of tropical forestry and environment vol. 9, no. 01 (2019) 7-18 13 (figure 4) and 9% lower vessel diameter than open sand bed and cma (table 3). vessel frequency was 53% higher in cuttings from covered sand beds than open sand beds and 97% higher than that of cma cuttings. open sand bed and cma cuttings had large sclerenchyma bundles in the bark region compared to covered sand beds (figure 4). table 3: anatomical configuration of lateral stem cuttings from different mother plant sources. cutting source pith (%) vessel frequency (per mm2) vessel diameter (µm) sand bed-sh 40.47 a 74.11 a 33.45 a sand bed-shade 42.46 a 78.44 a 31.07 a sand bed-open 52.28 b 48.44 b 36.97 b field cma 56.07 c 37.66 c 38.93 b significance cutting source *** *** *** *** significant at p<0.001, mean values of each trait with same letter do not vary significantly (p<0.05). 4. discussion adventitious roots are initiated in soft wood cuttings from certain focal cells in stem in response to wounding when removed from the mother plant. endogenous regulatory factors and environmental conditions play a role in successful rooting of cuttings. depending on the response different species can be classified as easy, difficult or moderately easy to root (ford et al., 2001). there could be several factors that inhibit or enable root initiation in stem cutting. juvenility of cutting plays a major role in deciding rooting response and root architecture of propagules of the same genotype. leucaena was considered difficult to root by the conventional propagation method of coppice shoots from stumps and hedges (litzow and shelton, 1991). exogenous application of rooting hormone, and selection of appropriate type of cuttings were identified to improve rooting rate in the genus (victorio et al., 1998; dick et al., 1999). endogenous rooting hormone iaa is normally synthesised in apical leaves and buds and basipetally transported to the stem base where they accumulate to initiate root primordia formation (ahkami et al., 2013). rooting can be low or delayed due to factors like maturation of tissues or lack of focal cells that initiate primordia. it is important to identify the factors that control rooting in a species (wilson, 1994) for addressing them through mother plant modification, exogenous hormone application or altering the environmental factors, and employing appropriate propagation conditions. 4.1 role of propagation conditions in rooting leucaena cuttings in the present study mc 1 had fine misting compared to mc 2. this resulted in difference in spray volume delivered to cuttings despite maintaining the same humidity with sensors. excess (or low) misting can affect water stress in cuttings which impact root initiation (greenwood et al., 1980) as evidenced by 19% higher rooting rate and 41% more roots in cuttings propagated in mc 1. a similar trend of higher rooting and number of roots was reported in black walnut when propagated in fog chambers compared to mist system (stevens and pijut, 2017). intermittent misting was less effective in controlling loss of turgor due to desiccation of compound leaves (like leucaena) in black walnut. cunha et al. (2009), reported a negative relationship between relative humidity and rooting rate in eucalypt minicuttings. dick et al. (1999), recommended use of small non mist propagators for successful rooting of leucaena by maintaining appropriate temperature and humidity conditions required at each stage of rooting. however, they reported a negative correlation between length of new shoots produced in cuttings 14 and rooting rate due to competition for assimilates in cuttings. delay in root primordia initiation is likely to restrict the number of roots produced due to competition of emerging shoots from dormant buds. basal accumulation of auxin in petunia stem cuttings was reported to be maximum in the first 24 hrs of excision of cuttings (ahkami et al., 2013) after which it declines. it is important to ensure that right temperature and humidity conditions are provided during the time of peak hormone accumulation for early root initiation in cuttings. this was quite evident in the present study where rooting rate and number of roots differed significantly between the two mist chambers indicating difference in propagation conditions of the two mist systems. there are no reports on the length of root zone or distribution of primary roots produced in leucaena stem cuttings. most studies used nodal cuttings from seedlings (dick et al., 1999), coppice shoots (shi and brewbaker, 2006) or mature stems (pandey and kumar, 2013) and hence had lower number of roots than the current study. when propagation conditions are not ideal or when mature stem cuttings are used, rooting is delayed with callus formation in leuceana (pandey and kumar, 2013) whereas direct emergence of primary roots is observed in lateral shoot cuttings (suraj and varghese, 2019). in such instances exogenous hormone application may help in root primordia initiation as seen in the current study. exogenous iba application was seen to enhance rooting rate in an earlier study in lateral shoots produced from field hedges (cma) but not in covered sand beds (suraj and varghese, 2019). rooting pattern was not evaluated in that study but rooting rate was high across seasons, which is also observed in the current study. this study clearly shows that appropriate propagation condition is very crucial for obtaining good quality root system in leucaena cuttings, which may not be reflected from the rooting success (leakey, 2004). 4.2 mother plant management for improving root traits it is observed that mother plant management has a significant impact on rooting in leucaena. juvenility status of cutting enhances the quantity of assimilates as well as endogenous hormone levels, compared to mature cuttings. dick et al. (1999) reported that stem cuttings of diameter 2.9-5.5 mm from nodes 5 to 13 from shoot apex was ideal for rooting in leucaena. rooting would still be variable due to difference in maturity levels of the cuttings at different positions. the present study has compared lateral stem cuttings of the same length (25-30 cm) and diameter range (2.5-3.3 mm) from four types of mother plants maintained in different environmental conditions. leakey and mohammed (1985), observed that cuttings of same length would have uniform physiology based on diameter, stem lignification, carbohydrate content and leaf water potential. the current study shows that stock plant management is quite important to obtain uniform cuttings of same juvenility and physiological condition. mother plants were cut to 15 cm height based on inference from a previous study (suraj and varghese, 2019), and pruned repeatedly to reorient the shoots to a horizontal angle for preventing competition from vertically growing shoots (leakey, 1983). pruning helps to maintain juvenility in mother plant and prevent maturation of stem whereby cuttings of uniform anatomical configuration can be obtained. light and heat conditions of mother plant play a role in controlling endogenous hormone levels (greenwood and hutchinson, 1993) and lignification in stem (maynard and bassuk, 1996). this trend was quite evident in the current study where thinner cuttings from sand beds maintained in shade had higher rooting and number of roots than those exposed to direct sunlight. it is evident that cuttings produced from field cmas were of higher maturity as indicated by the sclerenchyma bundles in stems, which has affected rooting rate and number of roots produced. high irradiation also causes greater competition among stems for apical dominance as indicated by lower angle of lateral shoot emergence in mother plants without shade (table 2). hoad and leakey (1996), reported higher rooting in eucalyptus grandis stock plants maintained under shade due to less competition between shoots and improved physiology of excised cuttings. the same trend was seen in the current study where open sand bed and cma cuttings had larger stem diameter and lower angle of emergence, and anatomical configuration of large pith region with low frequency of large diameter suraj et al. /journal of tropical forestry and environment vol. 9, no. 01 (2019) 7-18 15 vessels. mesen et al. (2001) reported a preconditioning influence of nutrition and light on rooting rate in albizia guachapele stock plants. figure 4: transverse sections of stem cuttings at 25 cm length from shoot apex in (a) field cma (b) sand beds in shade house (c) open sand beds and (d) sand beds with shade (scale bar=200 µm). [note the higher pith region, lower number of vessels per unit area and thicker sclerenchyma bundles in field cma and open sand beds compared to sand beds in covered shade house and sand beds under shade]. adventitious roots in woody perennials originate mostly from parenchyma cells close to the vascular system (bellini et al., 2014). maturation of stem as seen in stock plants of cma and open sand bed results in decrease of such focal cells due to reduction in number of vessels as well as increase in the lignified sclerenchyma tissues (stevens and pijut, 2017). this is probably the major reason for difference in rooting pattern (length of root zone) between the covered and open mother plants as there could be a reduction in the number of progenitor cells that give rise to roots. lateral cuttings of 25-30 cm length have higher frequency of low diameter vessels at the basal position than younger tissues in leucaena stem. rooting is therefore low in small young cuttings from apical positions (suraj and varghese, 2019). 4.3 management of lodging in leucaena plantations good root system is essential for ensuring mechanical stability of clonally propagated trees. adventitious roots formed within 20 days in mist chamber would be the major roots that support the above ground biomass of trees. lateral roots produced from these primary adventitious roots (bellini et al., 2014) would have less role in providing mechanical stability to the plant. hence it is important that mother plants are managed to obtain ideal cuttings that give maximum primary roots distributed all a b c d 16 around the stem with long root zone to support fast growth of clones. vegetative propagules in leucaena produce only about half the number of major roots compared to seedlings, without a prominent tap root. poor root distribution and lop sided rooting are major problems encountered in nodal cuttings of leucaena and eucalyptus (sachs et al., 1988) which can be addressed to an extent through minicuttings in eucalyptus and lateral shoots in leucaena (suraj and varghese, 2019). however, there is scope for improving rooting pattern by ensuring that a combination of right mother plant management practices, appropriate propagation conditions and best season for propagation is adopted. it is observed that almost 70% rooted cuttings from covered sand beds were of rooting category 3 to 5 (2.6-5.5 cm root zone) whereas in open sand beds and cma more than 85% plants were of category 1 and 2 (figure 2). this difference in root system can have an impact on the growth and stability of clonal plants. optimisation of cutting quality and propagation conditions can enhance the proportion of cuttings in higher rooting category (3 and above). most of the seedlings were of category 6 (>5.6 cm) whereas only about 6% sh cuttings were of category 5 (4.5-5.5 cm). leakey (2004) observed that rooting rate is not an indicator of efficient propagation, since root system of propagules could be very different. requirement of the species has to be evaluated for production of ideal propagules based on climatic conditions of nursery site. this was clearly demonstrated in a difficult to root african species cola anomala where partial shading of mother plants gave higher rooting and more number of roots. stock plants grown in high irradiance showed reduced sensitivity to exogenous hormone application and treatment with higher dose (10,000 ppm) increased rooting (kangegne et al., 2017). in leuceana the present study revealed that without iba treatment, propagules had smaller root zone despite achieving high rooting rate (above 80%). suitable agronomic practices need to be adopted like deep planting, to ensure that root system is not exposed, along with minimal disturbance to soil during weeding to prevent root damage. restricted irrigation may be given to ensure deeper growth of roots and reduced crown formation in first year after planting. it is observed that tree canopy can be restricted by providing close spacing (2 m×1 m) initially to give sufficient time for root growth followed by thinning to reduce stocking after establishment. pruning lower branches helps to reduce the crown spread and improve form of trees. 5. conclusion lateral shoot cuttings of leucaena vary in thickness and anatomical structure depending on management practice of mother plants. growth and environmental conditions like temperature and light influence rooting potential of cuttings. mother plants maintained in shade produce desirable type of cuttings that have high rooting and good root distribution along greater length of stem, than those raised in direct sunlight. propagation system has an influence on the proportion of rooted cuttings with long root zone. application of rooting hormone improves root zone length and number of roots. a combination of best practices of mother plant management, propagation conditions and hormone treatment would be necessary to produce uniform clonal planting stock with good root system in leucaena to reduce lodging in plantations. acknowledgment the authors thank mr. viswakarma, manager pspd, itc ltd. for nursery support, and nursery staff of itc pspd for help in data collection. references ahkami, a.h., melzer, m., ghaffari, r., pollmann s., javid m.g., shahinnia f., hajirezaei m.r. and druege, u., 2013. distribution of indole-3-acetic acid in petunia hybrid shoot tip cuttings and relationship between auxin transport, carbohydrate metabolism and adventitious root formation. planta, 238:499-517. badilla, y., xavier, a., murillo, o. and de paiva, h.n., 2016. iba efficiency on mini-cutting rooting from teak (tectona grandis linn f.) clones. revista árvore, 40:477-485. https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/cola-plant suraj et al. /journal of tropical forestry and environment vol. 9, no. 01 (2019) 7-18 17 bellini, c., pacurar, d.i. and perrone, i., 2014. adventitious roots and lateral roots: similarities and differences. annual review of plant biology, 65:639-666. cunha, a.c.m.c.m., paiva, h.n., leite, h.g., barros, n.f. and leite, h.p., 2009. relation of climate variables with eucalypt minicutting production and rooting. revista árvore, 33:195-203. de assis, t.f., fett-neto, a.g. and alfens, a.c., 2004. current techniques and prospects for the clonal propagation of hardwoods with emphasis on eucalyptus. in: walter c., carson m. (eds) plantation forest biotechnology for the 21st century. research signpost, 303-333. de assis, t.f., 2011. hybrids and mini-cutting: a powerful combination that has revolutionised the eucalyptus clonal forestry. bmc proceedings, 5:1-2. de klerk, g.j., van der krieken, w. and de jong, j.c., 1999. the formation of adventitious roots: new concepts, new possibilities. in vitro cellular and developmental biology-plant, 35:189-99 de mendiburu, f. and 2014. agricolae, statistical procedures for agricultural research. lima, peru: national engineering university. dick, j., magingo, f., smith r.i.and mcbeath, c., 1999. rooting ability of leucaena leucocephala stem cuttings. agroforestry systems, 42:149-157. ford, y.y., bonham, e.c., cameron, r.w.f., blake, p.s., judd, h.l. and harrison-murray, r.s., 2002. adventitious rooting: examining the role of auxin in an easyand a difficult-to-root plant. plant growth regulation, 36:149-159. gehlot, a., gupta, r.k., tripathi, a., arya, i.d. and arya, s., 2014. vegetative propagation of azadirachta indica: effect of auxin and rooting media on adventitious root induction in minicuttings. advances in forestry science, 1:1-9. greenwood, m.s., marino, t.m., meier, r.d. and shahan, k.w., 1980. the role of mist and chemical treatments in rooting loblolly and shortleaf pine cuttings. forest science, 26:651-655. greenwood, m.s. and hutchinson, k.w., 1993. maturation as a developmental process. in: ahuja m.r., libby w.j. (eds) clonal forestry 1: genetics and biotechnology. springer-verlag, berlin, 14-33. hoad, s.p. and leakey, r.r.b., 1996. effects of pre-severance light quality on the vegetative propagation of eucalyptus grandis w. hill ex maiden: cutting morphology, gas exchange and carbohydrate status during rooting. trees, 10:317-324. kangegne, g., mbouobda, h.d., fosto kamtat, g.f. and omokolo, d.n., 2017. interaction of stock plants shading and exogenous auxin on the propagation of cola anomala k. schum (malvaceae) by cuttings. south african journal of botany, 112:246-252. karim, a.b., rhodes, e.r. and savill, p.s., 1991. effect of cutting height and cutting interval on dry matter yield of leucaena leucocephala (lam) de wit. agroforestry systems, 16:129. leakey, r.r.b., 1983. stock plant factors affecting root initiation in cuttings of triplochiton scleroxylon k. schum., an indigenous hardwood of west africa. journal of horticultural science, 58:277290. leakey, r.r.b., 2004. physiology of vegetative reproduction. in: burley j., evans j., youngquist j.a. (eds) encyclopaedia of forest sciences. academic press, london, uk, 1655-1668. leakey, r.r.b. and mohammed, h.r.s., 1985. the effects of stem length on root initiation in sequential single-node cuttings of triplochiton scleroxylon k. schum. journal of horticultural science, 60:431-437. lebude, a.v., goldfarb, b., blazich, f.a., wise, f.c. and frampton, j., 2004. mist, substrate water potential and cutting water potential influence rooting of stem cuttings of loblolly pine. tree physiology, 24:823-831. litzow, d.r. and shelton, h.m., 1991. establishment of leucaena leucocephala and gliricidia sepium from stem cuttings. leucaena research reports, 12:3-6. https://www.sciencedirect.com/science/journal/02546299 18 mesén, f., leakey, r.r.b. and newton, a.c., 2001. the influence of stock plant environment on morphology, physiology and rooting of leafy stem cuttings of albizzia guachapele. new forests, 22:213-227. maynard, b.k. and bassuk, n.l., 1996. effects of stock plant etiolation, shading, banding and shoot development on histology and cutting propagation of carpinus betulus l. fastigiata. journal of the american society for horticultural science, 121:853-860. pandey, v.c. and kumar, a., 2013. leucaena leucocephala: an underutilised plant for pulp and paper production. genetic resources and crop evolution, 60:1165-1171 sachs, r.m., lee, c., ripperda, j. and woodward, r., 1988. selection and clonal propagation of eucalyptus. california agriculture, 42:27-31. shi, x. and brewbaker, j.l., 2006. vegetative propagation of leucaena hybrids by cuttings. agroforestry systems, 66:77-83. snedcor, w., cochran, g., 1980. statistical methods. 7th ed. iowa state university press. 507. stevens, m.e. and pijut, p.m., 2017. origin of adventitious roots in black walnut (juglans nigra) softwood cuttings rooted under optimised conditions in a fog chamber. new forests 48, 685-697. suraj, p.g. and varghese, m., 2019. evaluation of rooting in lateral shoots and nodal stem cuttings of leucaena (l. leucocephala and l. diversifolia) clones for clonal propagation. journal of tropical forest science, 31:50-62. victorio, e.e., acasio r.n., castillo a.c. and sacro m.f., 1998. initial experiences on the vegetative propagation of leucaena kx2f1 hybrid by rooted cuttings. pp 135-137 in: de la vina a.c., moong f.a. (eds) proceedings 6th meeting of the regional working group on grazing and feed resources for s.e asia on integrated crop-livestock production systems and fodder trees. 5-9 october, 1998, philippines, fao. visnovitz, t., világi, i., varró, p. and kristóf, z., 2007. mechanoreceptor cells on the tertiary pulvini of mimosa pudica l. plant signaling and behavior, 2:462-466. wilson, p.j., 1994. the concept of a limiting rooting morphogen in woody stem cuttings. journal of horticultural science, 69:591. microsoft word 7 cooray et al cooray et al., /journal of tropical forestry and environment vol. 2, no. 01 (2012) 60-68 60 spatial variability of soil characteristics along a landscape gradient in bellanwila-attidiya area s. cooray 1 , r.u.k. piyadasa* 2 and d.wickramasinghe 1 1 department of zoology, university of colombo, colombo, sri lanka, 2 department of geography, university of colombo, colombo, sri lanka date received: 16-10-2011 date accepted: 27-2-2012 abstract wetlands are comprised of unique components of soil, water and biodiversity which are interconnected. although water and biodiversity components of wetlands have been somewhat investigated, a very few research have been carried out to investigate soil properties. this study focused on spatial variability of soil chemical and physical parameters in a land use gradient around the bellanwila-attidiya sanctuary, it was carried out for a period of 3 months and several random soil samples were obtained from all land use areas. selected physical and chemical properties of soil were analyzed according to the standard methods and the gis maps were developed using arcview gis 3.2. the results indicated that selected chemical and physical parameters of soil varied across the land use gradient, except for temperature. according to the gis maps there are apparent variations in distribution of soil properties. on the surface, the highest level of each parameter was found as follows: no3 – industrial area, po4 3 functioning paddy fields, so4 2 residential area, cl residential area, fe 3+ functioning paddy fields, moisture content wetland, ph, acidic – industrial area, salinity residential area, electrical conductivity – residential area. at a 1 m depth, the pattern was different: no3 – abandoned paddy fields, po4 3 – functioning paddy fields, so4 2 wetland, cl wetland, fe 3+ residential area, moisture content wetland, ph – industrial area, salinity wetland, electrical conductivity wetland. the findings clearly exhibit the increases in anthropogenic pressure have resulted in wide-scale alternation of soil properties, at least in the surface soil, across a land use gradient. managing land use in the watershed of the wetland thus needs adequate attention to conserve this natural ecosystem. key words: soil, physical and chemical parameters, wetland, gis 1. introduction wetlands are comprised of characteristic components of soil, water and biodiversity which interact with each other to give rise to a unique environment (holland et al., 2003). wetlands are amongst the world’s most valuable and vulnerable environments on which a variety of plants, animals and human communities depend (kotagama and bambaradeniya, 2006; finlayson et al., 2007). given its favorable topography and climate, sri lanka supports a wide array of wetlands which possess various ecological functions and values. *correspondence: ranjana@geo.cmb.ac.lk tel-++ 94 11 2500458, fax++ 94 11 2500458 issn 2235-9370 print / issn 2235-9362 online ©2012 university of sri jayewardenepura cooray et al., /journal of tropical forestry and environment vol. 2, no. 01 (2012) 60-68 61 wetland ecosystems are dynamic and heterogenic, which can exhibit substantial spatial and temporal variability in soil properties (grunwaldet al., 2006) which can be influenced by the land use pattern of the area (bruland and richardson, 2005). this variability can have important consequences on wetland biota and biogeochemistry. soil of wetland often saturated, flooded, or inundated long enough during the growing season to develop anaerobic conditions in the upper part. the composition of soil of a wetland contributes to characteristics of the habitat. there are primarily two types of wetland soil, mineral soil and organic soil. almost all wetlands have organic soil, but if the organic matter content of the soil is less than 20-35 percent organic matter, it is considered a mineral soil (street, et al. 2005). table 1 depicts different properties of organic and mineral soils in wetlands. table 1: comparing mineral and organic soils in wetlands (street, et al. 2005) description mineral soil organic soil organic content, percent less than 20-35 greater than 2035 organic carbon, percent less than 12 to 20 greater than 1220 ph usually circumneutral acidic bulk density high low porosity low (45-55%) high (80%) hydraulic conductivity high (except for clays) low to high water holding capacity low high nutrient availability generally high often low cation exchange capacity low, dominated by major cations high, dominated by hydrogen ion typical wetland riparian forest, some marshes northern peatland wetland soils need to be evaluated based on the available nutrient levels, proportions of sand, silt, clay, gravel content, organic material, permeability, drainage potential, erodibility, soil chemistry (heidi, 1997). the incidence of these exceptional properties within the landscape can be used as indicators of wetland conditions to determine whether they are altered or not (cwikiel, 2003). soils can be referred to as media for processes, functions and primary production of an ecosystem (cosmas, 2009). it contains heterogeneity of nutrients that are made available to plants when the conditions are sufficient enough to make them solubilise (kidane and pieterse, 2006); and assimilable by plants.preservation of wetland habitat is of the utmost importance because the areas provide beneficial uses for humans, such as reducing soil erosion, recharging groundwater, and aesthetic beauty (united states environmental protection agency, 2001). wetlands are also involved in many biological and chemical processes which transform nutrients, sequester heavy metals and organic compounds (united states environmental protection agency, 2001). pollution from agricultural and other anthropogenic sources have been identified as the major cause of degradation of water bodies (united states environmental protection agency, 1996). although adequate attention has been paid to water and biodiversity components of wetlands, there are only a few studies that describe wetland soils in sri lanka (atapattu et al., 2007). this study investigates the spatial variability of soil chemical and physical parameters in a land use gradient around the bellanwila-attidiya sanctuary, situated in colombo suburbs. 2. materials and methods this study was conducted in bellanwila-attidiya wetland which is located in the south eastern bounds of colombo between 60 52’ 0 n and 790 52’ 0 e to 60 48’ 0 n and 790 56’ 0 e; 759157 n and 374779 e to 751770 n and 382129 e; in the colombo district of the western province. the marshes are about 372 hectares (approximately about 1,000 acres) in area. this is largely a freshwater marsh cooray et al., /journal of tropical forestry and environment vol. 2, no. 01 (2012) 60-68 62 ecosystem, bounded by a swiftly developing urban landscape (international water management institute, 2006). this study was carried out for a period of 3 months from february 2011 to april 2011 and the site was visited once in two weeks and soil samples were taken by using a soil borer in randomly selected places. sampling was carried out in triplicate on each day. the study site represented by the wetland itself (wl) which is the main marsh and surrounding different land use areas i.e. functioning paddy fields (fpf), abandoned paddy fields (apf), residential area (ra) and industrial area (ia) (figure 1). the soil chemical properties viz. no3 , po4 3, so4 2, cl , fe 3+ , ph, salinity and electrical conductivity and physical properties viz. moisture content, temperature, soil type and soil color were measured at two levels: at the surface level (top) and at 1 m depth (bottom) from the surface. samples were analyzed in the soil laboratory of the university of colombo. table 2 depicts the standard methods adopted to analyze soil samples. figure 1: land use map of the bellanwila-attidiya area by pooling data for a particular land use area, means and standard deviations were determined for each parameter investigated. one-way analysis of variance (anova) was used to compare soil properties among sites. least significant difference (lsd) multiple comparison analysis was carried out to identify which combinations of land use areas gave the significant difference from each other (p ≤ 0.05) in aforesaid parameters. all statistical analysis was performed using spss version 16.0 for windows. the gis maps were developed to indicate variation in physical and chemical parameters in relation to different land use areas. further gis was used to represent the study area and its land use patterns using arcview gis 3.2. data were positioned in the soil triangle to define the soil type of each area. soil colour was determined using munsell soil colour chart (black, 1965). cooray et al., /journal of tropical forestry and environment vol. 2, no. 01 (2012) 60-68 63 table 2: methods used in analysing physical and chemical parameters of soil soil parameter method temperature soil thermometer at the sampling site. (black,1965) soil moisture cont. drying method (black,1965) ph ph meter dipped in a soil-water suspension 1:2 (black,1965) salinity salinity-conductivity meter (black,1965) electrical conductivity salinity-conductivity meter (black,1965) soil type drying method (black,1965) soil colour munsell soil colour chart (black,1965) nitrate, phosphate and sulphate uv visible spectrophotometry (clesceriet al. 1999) chloride titration, silver nitrate method (clesceriet al. 1999) iron (iii) atomic absorption spectrophotometry (aas) (clesceri et al. 1999) 3. results according to soil analysis results, on average, higher percentage of clay was found in bottom soil layers of some areas. a similar pattern was observed when the soil triangle was developed using the data obtained. it showed that the soil type in bottom soil layers of all the land use areas were identified as clay soil, while the top soils of residential area and industrial area were also recognized as clay soil. both functioning paddy fields and abandoned paddy field have silt loam in its top soil layers. silt clay loam was the soil type in wetland top layer (table 3). table 3: soil colour and soil type in different land use areas land use layer soil type colour functioning paddy field surface silt loam pale brown 1 m clay gray abandoned paddy field surface silt loam very dark greyish brown 1 m clay gray wetland surface silt clay loam brownish black 1 m clay gray residential area surface clay bright brown 1 m clay gray industrial area surface clay bright brown 1 m clay bright brown the results further indicated that all chemical and physical parameters of soil varied across the land use gradient, except for temperature. the results are summarized in table 4. the highest values obtained for all parameters differed in different land use settings (table 4). the pattern observed for the highest levels for each parameter on the surface was found as follows: on the surface: no3 – industrial area, po4 3 functioning paddy fields, so4 2 residential area, cl residential area, fe 3+ functioning paddy fields, moisture content wetland, ph – industrial area, salinityresidential area, electrical conductivity – residential area. at a 1 m depth the pattern was different: no3 – abandoned paddy fields, po4 3 – functioning paddy fields, so4 2 wetland, cl wetland, fe 3+ residential area, moisture content wetland, ph – industrial area, salinity wetland, electrical conductivity – wetland. cooray et al., /journal of tropical forestry and environment vol. 2, no. 01 (2012) 60-68 64 table 4: mean ± sd of soil parameters along a land use gradient maps generated using gis data indicating the distribution of nitrate and phosphate levels in different land use areas in both top and bottom soil layers are depicted in figures 2, 3, 4, and 5 respectively. land use functioning paddy filed abandoned paddy field wetland residential area industrial area chemical/ physical parameters mean ± sd surface 1 m surface 1 m surface 1 m surface 1 m surface 1 m moisture content (%) 43.08 ±4.16 37.51 ±3.75 42.35 ±3.34 36.66 ±2.37 62.66 ±4.37 60.35 ±2.63 49.57 ±3.36 50.85 ±3.24 17.07 ±2.12 21.96 ±2.25 ph 5.95 5.59 5.93 5.28 5.59 3.53 5.57 3.15 6.80 6.35 ±0.47 ±0.45 ±0.76 ±0.49 ±0.70 ±0.63 ±0.93 ±0.57 ±0.90 ±0.69 salinity (ppt) 0.12 0.18 0.12 0.17 0.35 3.60 0.60 3.20 0.42 0.80 ±0.20 ±0.27 ±0.20 ±0.29 ±0.29 ±1.27 ±0.33 ±1.06 ±0.51 ±0.62 temperature (°c) 29.08 ±1.53 27.58 ±1.69 29.67 ±1.53 28.83 ±1.88 30.42 ±1.30 28.25 ±1.19 31.00 ±1.12 28.83 ±1.21 30.75 ±0.99 30.08 ±1.44 electrical conductivity (µs) 366.15 ±14.07 552.28 ±13.74 391.73 ±13.34 404.92 ±13.82 824.30 ±17.02 6985.33 ±51.05 1548.78 ±20.07 5675.50 ±41.72 1436.05 ±24.62 2296.22 ±27.63 [no3-] (ppm) 0.38 0.65 0.48 0.71 0.15 0.13 0.35 0.44 0.67 0.20 ±0.33 ±0.21 ±0.49 ±0.38 ±0.28 ±0.38 ±0.30 ±0.44 ±0.54 ±0.28 [po4 3-] (ppm) 11.42 ±2.92 27.94 ±2.88 3.32 ±1.38 11.27 ±1.02 2.62 ±0.80 1.70 ±0.83 2.49 ±1.02 2.64 ±1.16 1.72 ±0.79 0.85 ±0.55 [so4 2-] (ppm) 72.18 ±3.28 77.60 ±4.29 48.99 ±3.71 50.90 ±3.30 142.0 ±4.18 1461.06 ±27.48 247.04 ±5.90 540.14 ±27.58 180.03 ±8.76 230.69 ±12.27 [cl-] (ppm) 0.28 ±0.07 0.47 ±0.68 0.28 ±0.06 0.30 ±0.25 1.25 ±0.63 5.01 ±1.17 2.42 ±0.83 4.31 ±0.91 0.99 ±0.65 0.31 ±0.24 [fe3+] (ppm) 2.90 0.36 0.07 0.05 1.22 0.29 1.17 1.90 0.06 0.05 figure 2: distribution of water soluble nitrates in top soil layer in the study area figure 3: distribution of water soluble nitrate in bottom soil layer in the study area cooray et al., /journal of tropical forestry and environment vol. 2, no. 01 (2012) 60-68 65 figure 4: distribution of water soluble phosphate in top soil layer in the study area figure 5: distribution of water soluble phosphate in bottom soil layer in the study area salinity, electrical conductivity and chloride level showed a significant variability in top and bottom soils in different land use areas. the decline of salinity and electrical conductivity levels were recorded as; top: residential area > industrial area > wetland > functioning paddy field = abandoned paddy field bottom: wetland > residential area > industrial area > functioning paddy field > abandoned paddy field chloride levels in the top soil layer showed a similar declining pattern except for the fact that chloride level in industrial area was overridden by the chloride level in residential area, while the bottom layer resembled exactly the same. increased chloride, salinity and electrical conductivity level of the wetland and residential area (figure 6, 7 and 8), indicate saline intrusion. figure 6: distribution of salinity in bottom soil layer in the study area figure 7: distribution of electrical conductivity in bottom soil layer in the study area cooray et al., /journal of tropical forestry and environment vol. 2, no. 01 (2012) 60-68 66 figure 8: distribution of water soluble chloride in bottom soil layer in the study area 4. discussion bellanwila-attidiya wetland is the only natural landscape we came across in the study area and its soil resembled of typical wetland soil. it had high clay and moisture contents and lower ph (highly acidic) which is a characteristic property of hydric soils (mitsch and gosselink 1993, cited in street, et al. 2005). industrial area showed a significant difference in moisture content in both top and bottom soil layers from all the other land use areas, may be due to the high elevation levels recorded in the industrial area comparative to other land use areas. a nitrate and phosphate contents were low in the wetland soil due to microbial reactions under anaerobic (evens et al. 1996; campbell et al., 2002) owing to water logged conditions (omoregie and akenova, 1999). low level of nitrates and phosphates in top soils of functioning and abandoned paddy fields may be due to the same reason. increase of nitrates and phosphates in bottom soil layer of functioning paddy field may be because of leaching (chen et al. 2006) of nutrients supplemented by fertilizers (glendininget al., 1996, mukherjee et al., 2009). elevated nitrate level was recorded in top soil layer in industrial area because absence of denitrification due to aerobic conditions of the soil which inhibits denitrification process and combustion of fossil fuels that produce nox gasses which ultimately enriches soil by nitrates via precipitation (miroslav and vladimir, 1999). increased sulphate level in the wetland soil concurrent with literature had identified wetlands as sulphate sink (richardson, 1995). further wetland showed a significant difference in its bottom layer sulphate level from all the other land use areas while showing a significant difference with functioning paddy field, abandoned paddy field and residential area in top soil layer at 0.05 significant level. highest level of iron (iii) was recorded in top soil of functioning paddy filed whilst residential area reported the highest level in bottom layer. the iron (iii) levels in different land use areas arranged in descending order are as following; top: functioning paddy field > wetland > residential area > abandoned paddy field > industrial area, bottom: residential area > functioning paddy field > wetland> abandoned paddy field = industrial area. the density of saline water is much higher than fresh water. hence sea water intrusion generally occurs through bottom soil layers. studies focused on bolgoda lake which is connected to the surface cooray et al., /journal of tropical forestry and environment vol. 2, no. 01 (2012) 60-68 67 network of the bellanwila-attidiya wetland, reported elevated levels of salinity in the channel system (piyadasa and chandrasekara, 2010) which might have consequently contributed to the elevated salinity levels in soil. the lack of wetland studies reporting physical and chemical soil properties in the country makes it difficult to compare the levels that were found in this study. this study should be extended to include other important parameters including soil carbon contents and redox potentials. nevertheless, these results could use as baseline data in wetland conservation planning. 5. conclusion while the soil properties of wetland resembles more of less “typical wetland soils”, those in all other land use areas exhibit much variation indicating high human influences at least on the surface layers maps generated using gis that have been developed clearly show the patterns of variation of soil properties. acknowledgements: authors gratefully acknowledge the financial and logistical support provided by the university of colombo. references atapattu s.s., de silva, s. and sellamuttu, s.s., 2007. a case for integrated water resource management in sri lanka. wetlands and agriculture international irrigation management institute, colombo, sri lanka. black, c.a.(eds.) 1965. methods of soil analysis, part 1, physical and mineralogical properties, including statistics of measurement and sampling. american society of agronomy, inc. p. 82-127, 331-344, 545-566. bruland, g. l. and richardson, c.j. 2005. spatial variability of soil properties in created, restored and paired natural wetlands. soil science society of america journal 69, 273–84 campbell, d.a., c.a. cole, and r.p. brooks. 2002. a comparison of created and natural wetlands in pennsylvania, usa. wetlands ecol. and mgmt. 10, 41-49 chen, x.m., wu, h.s. and sun, j.h. 2006. time-spatial variability of ammonium and nitrate in farmland soil of taihu lake region, abs. huan jing kexue, 2006 jun; 27(6), 1217-1222 clesceri, l.s., greenberg, a.e. and eaton, a.d. 1999.standard methods for examination of water & wastewater, 20th edition. washington d.c: american public health association, the american water works association, and the water environment federation cosmas m. 2009. determination of the soil organic carbon, nitrogen, available phosphorus and the combined aboveground plant materials in the semi-arid mbulu district, tanzania. african journal of ecology, 47, 352–359 cwikiel, wilfred. 2003.michigan wetlands – yours to protect: a citizen’s guide to wetland protection. third edition.tip of the mitt watershed council, petoskey, mi 49770 evens, r., gilliam, j. and lilly, j. 1996.wetlands and water quality. north carolina cooperative extension service, [online] available from: www.bae.ncsu.edu/programs/extension/evans/ag4737.html [accessed 8th november 2010]. finlayson, c. m. 2007. irrigation versus ecosystems: what are the choices?’ journal of the australian water association. [online] available from: http://ibcperu.nuxit.net/doc/isis/7578.pdf glendining, m. j.,powlson, d. s.,poulton, p. r., bradbury, n. j., palazzo, d. and ll, x. 1996. the effects of long-term applications of inorganic nitrogen fertilizer on soil nitrogen in the broadbalk wheat experiment, abs. the journal of agricultural science, 127, 347-363 grunwald, s., corstanje, r., weinrich, b.e. and reddy, k.r. 2006. spatial patterns of labile forms of phosphorus in a subtropical wetland. journal of environmental quality 35, 378–89 cooray et al., /journal of tropical forestry and environment vol. 2, no. 01 (2012) 60-68 68 heidi, m. n. and carolyn, e.o.,1997. exchange dynamics of a shallow contaminated wetland boundaries. volume, 193-213 holland, m., blood, e.r. and shaffer, l.r. 2003. achieving sustainable freshwater systems: a web of connections, island press international water management institute 2006.sri lanka wetlands information and database, bellanwila-attidiya sanctuary, [online], available from: http://dw.iwmi.org/wetland_profile/bellanwila.asp [accessed 6th november 2010] kidane, g. and pieterse, j. 2006. impact of grazing around a watering point on soil status of semi-arid rangelands in ethiopia. afr. j. ecol. 45, 72–79 kotagama, s.w. and bambaradeniya, c.n.b 2006. an overview of the wetlands of sri lanka and their conservation significance. national wetland directory of sri lanka, iucn sri lanka and central environmental authority, 7-16 miroslav, r. and vladimir, b.n. 1999.practical environmental analysis. cambridge, uk: royal society of chemistry [online] available from: http://books.google.com.ec/books?id=o1f4hcvblsgc&printsec=frontcover&hl=en#v=onepage&q& f=false, [accessed 10 th june 2011] mukherjee, a., nair, v.d., clark, m.w. and reddy, k.r. 2009. development of indices to predict phosphorus release from wetland soils, journal of environmental quality, volume 38, may–june 2009, 878-886. omoregie, a.u. and akenova, m.e. 1999.p status and sorption capacities of some native rangeland soils in northern nigeria. tropical agricultural research and extension, 2 (2), 101-106 piyadasa, r. and chandreasekara, k. 2010. land use pattern and their impact on water quality in bolgoda lake basinsri lanka, abs. geophysical research abstracts, volume 12, egu2010, 1195 richardson, c.j. 1995. wetland ecology. in nierenberg, w.a. (eds) encyclopaedia of environmental biology, volume 3, academic press. inc. 535-550 street, m.w., deaton, a.s.,chapell, w.s. and mooreside, p.d. 2005. north carolina coastal habitat protection plan. north carolina department of environment and natural resources, division of marine fisheries, morehead city, nc. 656 united states environmental protection agency 1996. environmental indicators of water quality in the united states. epa 841-r-96-002. office of water (4503f). u.s. environmentalprotection agency, washington, dc. united states environmental protection agency 2001.values and function of wetlands. september 2001. available from: http://www.epa.gov/owow/wetlands/pdf/fun_val.pdf [accessed 3 rd november, 2011] microsoft word 1 de alwis feature de alwis/journal of tropical forestry and environment vol. 2, �o. 01 (2012) 1-9 1 feature article a tool for sustainability: a case for biogas in sri lanka a. a. p. de alwis* 1 * 1 professor of chemical and process engineering, department of chemical and process engineering university of moratuwa, moratuwa, sri lanka introduction sri lanka at present oscillates between an energy crisis and an economic crisis now entwined as a result of costly private power purchase agreements based on thermal power aggravated by rising fuel prices. the country indeed can claim to be the only country in the region to provide uninterrupted power to the consumer but the situation at present had been realized at an enormous cost. the loss for the ceylon electricity board (ceb) in the last year had been stated to be rs. 53 billion, no small amount which could have been well used elsewhere. the power purchases are soft options and at the heart of operations lies the process of generation. on the agriculture front, the government is engaged in a costly subsidy operation with respect to the provision of fertiliser while the responsible scientists lament about the serious degradation in soil quality as provision of soil amendments etc. are not taking place. this is resulting in lower yields but with higher costs of production. there is a serious opportunity for organic matter to be used up in this area. the write up is to be courageous in thinking about biogas based power generation in a big way while realising additional benefits which will really give meaning to the statement sustainable processes in national economic management and development. the interest in renewable energy systems is continuing across the globe in all types of economies and sri lanka is no exception. however, in the context of sri lanka biogas can said to be the ‘cinderella’ among all renewable as yet the attention that it justly deserves due to its ‘beautiful potential’ has not materialised. the longer the country delays this the costlier it would be for any implementation. while many express the benefits and the potential of biogas, influential publications in sri lanka fails to allocate even up to a paragraph on this versatile technology option. as summarised in figure 1 from chanakya (2002) the versatility of biogas stems from its ability to address any emerging issue of the time. the biogas initially appeared in supporting public health in developing economies and quickly migrated to addressing energy security for the poor under the energy crisis of seventies. today it appears to be a front line option in addressing the threat pose by climate change. biogas as a combination of methane and carbon dioxide provide a natural gas mix in working to produce nanomaterials in the emerging nanotechnology revolution which in turn will lead to a new material platform (vamathevan, 2011).natural gas along with carbon dioxide had been experimented upon by many to realise ‘syngas’ from which various energy and material pathways can be derived and in biogas one realises both together from waste materials by biological action. the captivity by ‘cinderella’ still eludes the planner and the policy maker. *correspondence: ajith@uom.lk tel: +94 11 2650301, fax: +94 11 2650 622 issn 2235-9370 print / issn 2235-9362 online ©2012 university of sri jayewardenepura de alwis/journal of tropical forestry and environment vol. 2, �o. 01 (2012) 1-9 2 biogas in sri lanka sri lanka has experience with biogas systems for a long period though the results can said to be of mixed quality. this has resulted in biogas being relegated to a small scale energy delivery opportunity at best and do not find any mention in influential publications. the opportunity with biogas as an option in energy delivery systems was identified a long time ago as a feasible and desirable for sri lanka again perhaps with the same background thought as in this case sri lanka was seen as a country with a significant segment of population struggling for energy. this resulted in a program of the united nations adopting the resolution as colombo declaration way back in april 1974 after a meeting in colombo, which stated that one of the urgent priorities in the region is energy. subsequently, a project for the development of anaerobic digestion throughout asia was approved in november 1974 which was championed by a pakistani nuclear scientist dr usmani who was with unep at the time. however, much of asia had really not benefited from developments in this area and energy shortage problems are quite common within the region. even the flagship project started in sri lanka under unep’s rural energy project, the pattiyapola center in the hambantota district failed to fulfil its expectations though it demonstrated the potential. the pattiyapola scheme was to be a rural energy research project experimental station (barnett et al, 1978) and was planned as one per each continent. de alwis (2001) discusses this project in some detail. figure 1: biogas potential across multiple issues facing the world it is unlikely that biogas can serve as a cure for all energy problems of sri lanka but this can be classified as a triple benefit technology and can challenge any other renewable energy technology to show similar capabilities. sri lanka should have sufficient energy, produced in an efficient manner, and in this biogas technologies can play a vital role as a steady state renewable energy supply operating in a decentralised manner. it can serve as an efficient environmental management tool. with some individuals it can play the role of improving their quality of life while reducing the economic burden. for the farming community it will serve as a useful ‘fertiliser’ supply using their own waste products. much foreign exchange can be saved and external energy dependence reduced. improved technological competitiveness and competence resulting from this type of strategy will benefit other areas as well. it is indeed continues sustainable option is ignored. biogas provides the best ‘well technology supported study demonstrated the applicability in a local context with the use of a better gas digester system and further work is awaited (kularathne et al, 20 indica triple issues and aligning triple benefits through ♦ are bound to rise and the country should be ready with technology options to serve energy needs of both stationary and mobile sectors. demand made on energy will increase and these need is indeed continues sustainable option is ignored. biogas provides the best ‘well technology supported study demonstrated the applicability in a local context with the use of a better gas digester system and further work is awaited (kularathne et al, 20 indica triple issues and aligning triple benefits through ♦ sri lanka are bound to rise and the country should be ready with technology options to serve energy needs of both stationary and mobile sectors. demand made on energy will increase and these need is indeed continues sustainable option is ignored. biogas provides the best ‘well technology supported study demonstrated the applicability in a local context with the use of a better gas digester system and further work is awaited (kularathne et al, 20 indicates the uom pilot project and potential is indeed worth thinking about. figure 2: pilot scale demonstration of biogas as a transport fuel at university of moratuwa triple issues and aligning triple benefits through sri lanka are bound to rise and the country should be ready with technology options to serve energy needs of both stationary and mobile sectors. demand made on energy will increase and these need biogas feeding to the is indeed a pity that in sri lanka planners is oblivious to these opportunities with one technology an continues sustainable option is ignored. biogas provides the best ‘well technology supported study demonstrated the applicability in a local context with the use of a better gas digester system and further work is awaited (kularathne et al, 20 tes the uom pilot project and potential is indeed worth thinking about. figure 2: pilot scale demonstration of biogas as a transport fuel at university of moratuwa triple issues and aligning triple benefits through sri lanka are bound to rise and the country should be ready with technology options to serve energy needs of both stationary and mobile sectors. demand made on energy will increase and these need biogas feeding to the three a pity that in sri lanka planners is oblivious to these opportunities with one technology an to pursue different pathways in fulfilling requirements in three different ways. a truly sustainable option is ignored. biogas provides the best ‘well technology supported study demonstrated the applicability in a local context with the use of a better gas digester system and further work is awaited (kularathne et al, 20 tes the uom pilot project and potential is indeed worth thinking about. figure 2: pilot scale demonstration of biogas as a transport fuel at university of moratuwa triple issues and aligning triple benefits through sri lanka lack are bound to rise and the country should be ready with technology options to serve energy needs of both stationary and mobile sectors. demand made on energy will increase and these need pilot scale biogas biogas feeding to the three a pity that in sri lanka planners is oblivious to these opportunities with one technology an to pursue different pathways in fulfilling requirements in three different ways. a truly sustainable option is ignored. biogas provides the best ‘well technology supported study demonstrated the applicability in a local context with the use of a better gas digester system and further work is awaited (kularathne et al, 20 tes the uom pilot project and potential is indeed worth thinking about. figure 2: pilot scale demonstration of biogas as a transport fuel at university of moratuwa triple issues and aligning triple benefits through lack are bound to rise and the country should be ready with technology options to serve energy needs of both stationary and mobile sectors. demand made on energy will increase and these need pilot scale biogas biogas feeding to the three-wheeler a pity that in sri lanka planners is oblivious to these opportunities with one technology an to pursue different pathways in fulfilling requirements in three different ways. a truly sustainable option is ignored. biogas provides the best ‘well technology supported study demonstrated the applicability in a local context with the use of a better gas digester system and further work is awaited (kularathne et al, 20 tes the uom pilot project and potential is indeed worth thinking about. figure 2: pilot scale demonstration of biogas as a transport fuel at university of moratuwa triple issues and aligning triple benefits through lacks conventional sources of energy and as fossil fuel supplies dry out the purchase costs are bound to rise and the country should be ready with technology options to serve energy needs of both stationary and mobile sectors. demand made on energy will increase and these need pilot scale biogas plant biogas feeding to the wheeler de alwis/ a pity that in sri lanka planners is oblivious to these opportunities with one technology an to pursue different pathways in fulfilling requirements in three different ways. a truly sustainable option is ignored. biogas provides the best ‘well technology supported study demonstrated the applicability in a local context with the use of a better gas digester system and further work is awaited (kularathne et al, 20 tes the uom pilot project and potential is indeed worth thinking about. figure 2: pilot scale demonstration of biogas as a transport fuel at university of moratuwa triple issues and aligning triple benefits through conventional sources of energy and as fossil fuel supplies dry out the purchase costs are bound to rise and the country should be ready with technology options to serve energy needs of both stationary and mobile sectors. demand made on energy will increase and these need pilot scale biogas plant biogas feeding to the wheeler de alwis/ a pity that in sri lanka planners is oblivious to these opportunities with one technology an to pursue different pathways in fulfilling requirements in three different ways. a truly sustainable option is ignored. biogas provides the best ‘well technology supported study demonstrated the applicability in a local context with the use of a better gas digester system and further work is awaited (kularathne et al, 20 tes the uom pilot project and potential is indeed worth thinking about. figure 2: pilot scale demonstration of biogas as a transport fuel at university of moratuwa triple issues and aligning triple benefits through conventional sources of energy and as fossil fuel supplies dry out the purchase costs are bound to rise and the country should be ready with technology options to serve energy needs of both stationary and mobile sectors. demand made on energy will increase and these need pilot scale biogas biogas feeding to the wheeler de alwis/ a pity that in sri lanka planners is oblivious to these opportunities with one technology an to pursue different pathways in fulfilling requirements in three different ways. a truly sustainable option is ignored. biogas provides the best ‘well technology supported study demonstrated the applicability in a local context with the use of a better gas digester system and further work is awaited (kularathne et al, 20 tes the uom pilot project and potential is indeed worth thinking about. figure 2: pilot scale demonstration of biogas as a transport fuel at university of moratuwa triple issues and aligning triple benefits through conventional sources of energy and as fossil fuel supplies dry out the purchase costs are bound to rise and the country should be ready with technology options to serve energy needs of both stationary and mobile sectors. demand made on energy will increase and these need pilot scale biogas biogas feeding to the de alwis/journal of tropical forestry and environment vol. 2, �o. 01 (2012) a pity that in sri lanka planners is oblivious to these opportunities with one technology an to pursue different pathways in fulfilling requirements in three different ways. a truly sustainable option is ignored. biogas provides the best ‘well technology supported study demonstrated the applicability in a local context with the use of a better gas digester system and further work is awaited (kularathne et al, 20 tes the uom pilot project and potential is indeed worth thinking about. figure 2: pilot scale demonstration of biogas as a transport fuel at university of moratuwa triple issues and aligning triple benefits through conventional sources of energy and as fossil fuel supplies dry out the purchase costs are bound to rise and the country should be ready with technology options to serve energy needs of both stationary and mobile sectors. demand made on energy will increase and these need pilot scale biogas journal of tropical forestry and environment vol. 2, �o. 01 (2012) a pity that in sri lanka planners is oblivious to these opportunities with one technology an to pursue different pathways in fulfilling requirements in three different ways. a truly eu has shown in the light of climate change mitigation studies that biogas provides the best ‘welltechnology supported study demonstrated the applicability in a local context with the use of a better gas digester system and further work is awaited (kularathne et al, 20 tes the uom pilot project and potential is indeed worth thinking about. figure 2: pilot scale demonstration of biogas as a transport fuel at university of moratuwa triple issues and aligning triple benefits through conventional sources of energy and as fossil fuel supplies dry out the purchase costs are bound to rise and the country should be ready with technology options to serve energy needs of both stationary and mobile sectors. as the standards of living improve and per capita income changes the demand made on energy will increase and these need journal of tropical forestry and environment vol. 2, �o. 01 (2012) a pity that in sri lanka planners is oblivious to these opportunities with one technology an to pursue different pathways in fulfilling requirements in three different ways. a truly eu has shown in the light of climate change mitigation studies that -to-wheel’ fuel and this technology supported study demonstrated the applicability in a local context with the use of a better gas digester system and further work is awaited (kularathne et al, 20 tes the uom pilot project and potential is indeed worth thinking about. figure 2: pilot scale demonstration of biogas as a transport fuel at university of moratuwa triple issues and aligning triple benefits through conventional sources of energy and as fossil fuel supplies dry out the purchase costs are bound to rise and the country should be ready with technology options to serve energy needs of both as the standards of living improve and per capita income changes the demand made on energy will increase and these need journal of tropical forestry and environment vol. 2, �o. 01 (2012) a pity that in sri lanka planners is oblivious to these opportunities with one technology an to pursue different pathways in fulfilling requirements in three different ways. a truly eu has shown in the light of climate change mitigation studies that wheel’ fuel and this technology supported study demonstrated the applicability in a local context with the use of a better gas digester system and further work is awaited (kularathne et al, 20 tes the uom pilot project and potential is indeed worth thinking about. figure 2: pilot scale demonstration of biogas as a transport fuel at university of moratuwa triple issues and aligning triple benefits through conventional sources of energy and as fossil fuel supplies dry out the purchase costs are bound to rise and the country should be ready with technology options to serve energy needs of both as the standards of living improve and per capita income changes the demand made on energy will increase and these need journal of tropical forestry and environment vol. 2, �o. 01 (2012) a pity that in sri lanka planners is oblivious to these opportunities with one technology an to pursue different pathways in fulfilling requirements in three different ways. a truly eu has shown in the light of climate change mitigation studies that wheel’ fuel and this technology supported study demonstrated the applicability in a local context with the use of a better gas digester system and further work is awaited (kularathne et al, 20 tes the uom pilot project and potential is indeed worth thinking about. figure 2: pilot scale demonstration of biogas as a transport fuel at university of moratuwa triple issues and aligning triple benefits through conventional sources of energy and as fossil fuel supplies dry out the purchase costs are bound to rise and the country should be ready with technology options to serve energy needs of both as the standards of living improve and per capita income changes the demand made on energy will increase and these need journal of tropical forestry and environment vol. 2, �o. 01 (2012) a pity that in sri lanka planners is oblivious to these opportunities with one technology an to pursue different pathways in fulfilling requirements in three different ways. a truly eu has shown in the light of climate change mitigation studies that wheel’ fuel and this technology supported study demonstrated the applicability in a local context with the use of a better gas digester system and further work is awaited (kularathne et al, 20 tes the uom pilot project and potential is indeed worth thinking about. figure 2: pilot scale demonstration of biogas as a transport fuel at university of moratuwa triple issues and aligning triple benefits through conventional sources of energy and as fossil fuel supplies dry out the purchase costs are bound to rise and the country should be ready with technology options to serve energy needs of both as the standards of living improve and per capita income changes the demand made on energy will increase and these need first ignition biogas journal of tropical forestry and environment vol. 2, �o. 01 (2012) a pity that in sri lanka planners is oblivious to these opportunities with one technology an to pursue different pathways in fulfilling requirements in three different ways. a truly eu has shown in the light of climate change mitigation studies that wheel’ fuel and this technology supported study demonstrated the applicability in a local context with the use of a better gas digester system and further work is awaited (kularathne et al, 20 tes the uom pilot project and potential is indeed worth thinking about. figure 2: pilot scale demonstration of biogas as a transport fuel at university of moratuwa triple issues and aligning triple benefits through conventional sources of energy and as fossil fuel supplies dry out the purchase costs are bound to rise and the country should be ready with technology options to serve energy needs of both as the standards of living improve and per capita income changes the demand made on energy will increase and these need first ignition biogas journal of tropical forestry and environment vol. 2, �o. 01 (2012) a pity that in sri lanka planners is oblivious to these opportunities with one technology an to pursue different pathways in fulfilling requirements in three different ways. a truly eu has shown in the light of climate change mitigation studies that wheel’ fuel and this technology supported study demonstrated the applicability in a local context with the use of a better gas digester system and further work is awaited (kularathne et al, 20 tes the uom pilot project and potential is indeed worth thinking about. figure 2: pilot scale demonstration of biogas as a transport fuel at university of moratuwa triple issues and aligning triple benefits through conventional sources of energy and as fossil fuel supplies dry out the purchase costs are bound to rise and the country should be ready with technology options to serve energy needs of both as the standards of living improve and per capita income changes the demand made on energy will increase and these need first ignition biogas journal of tropical forestry and environment vol. 2, �o. 01 (2012) a pity that in sri lanka planners is oblivious to these opportunities with one technology an to pursue different pathways in fulfilling requirements in three different ways. a truly eu has shown in the light of climate change mitigation studies that wheel’ fuel and this technology supported study demonstrated the applicability in a local context with the use of a better gas digester system and further work is awaited (kularathne et al, 20 tes the uom pilot project and potential is indeed worth thinking about. figure 2: pilot scale demonstration of biogas as a transport fuel at university of moratuwa triple issues and aligning triple benefits through b conventional sources of energy and as fossil fuel supplies dry out the purchase costs are bound to rise and the country should be ready with technology options to serve energy needs of both as the standards of living improve and per capita income changes the demand made on energy will increase and these need to be always factored in. a first ignition biogas journal of tropical forestry and environment vol. 2, �o. 01 (2012) a pity that in sri lanka planners is oblivious to these opportunities with one technology an to pursue different pathways in fulfilling requirements in three different ways. a truly eu has shown in the light of climate change mitigation studies that wheel’ fuel and this technology supported study demonstrated the applicability in a local context with the use of a better gas digester system and further work is awaited (kularathne et al, 20 tes the uom pilot project and potential is indeed worth thinking about. figure 2: pilot scale demonstration of biogas as a transport fuel at university of moratuwa biogas conventional sources of energy and as fossil fuel supplies dry out the purchase costs are bound to rise and the country should be ready with technology options to serve energy needs of both as the standards of living improve and per capita income changes the to be always factored in. a dry batch pit first ignition journal of tropical forestry and environment vol. 2, �o. 01 (2012) a pity that in sri lanka planners is oblivious to these opportunities with one technology an to pursue different pathways in fulfilling requirements in three different ways. a truly eu has shown in the light of climate change mitigation studies that wheel’ fuel and this is significant. ministry of science and technology supported study demonstrated the applicability in a local context with the use of a better gas digester system and further work is awaited (kularathne et al, 20 tes the uom pilot project and potential is indeed worth thinking about. figure 2: pilot scale demonstration of biogas as a transport fuel at university of moratuwa iogas conventional sources of energy and as fossil fuel supplies dry out the purchase costs are bound to rise and the country should be ready with technology options to serve energy needs of both as the standards of living improve and per capita income changes the to be always factored in. a dry batch pit journal of tropical forestry and environment vol. 2, �o. 01 (2012) a pity that in sri lanka planners is oblivious to these opportunities with one technology an to pursue different pathways in fulfilling requirements in three different ways. a truly eu has shown in the light of climate change mitigation studies that is significant. ministry of science and technology supported study demonstrated the applicability in a local context with the use of a better gas digester system and further work is awaited (kularathne et al, 20 tes the uom pilot project and potential is indeed worth thinking about. figure 2: pilot scale demonstration of biogas as a transport fuel at university of moratuwa conventional sources of energy and as fossil fuel supplies dry out the purchase costs are bound to rise and the country should be ready with technology options to serve energy needs of both as the standards of living improve and per capita income changes the to be always factored in. a dry batch pit journal of tropical forestry and environment vol. 2, �o. 01 (2012) a pity that in sri lanka planners is oblivious to these opportunities with one technology an to pursue different pathways in fulfilling requirements in three different ways. a truly eu has shown in the light of climate change mitigation studies that is significant. ministry of science and technology supported study demonstrated the applicability in a local context with the use of a better gas digester system and further work is awaited (kularathne et al, 20 tes the uom pilot project and potential is indeed worth thinking about. figure 2: pilot scale demonstration of biogas as a transport fuel at university of moratuwa conventional sources of energy and as fossil fuel supplies dry out the purchase costs are bound to rise and the country should be ready with technology options to serve energy needs of both as the standards of living improve and per capita income changes the to be always factored in. a external sources dry batch pit journal of tropical forestry and environment vol. 2, �o. 01 (2012) a pity that in sri lanka planners is oblivious to these opportunities with one technology an to pursue different pathways in fulfilling requirements in three different ways. a truly eu has shown in the light of climate change mitigation studies that is significant. ministry of science and technology supported study demonstrated the applicability in a local context with the use of a better gas digester system and further work is awaited (kularathne et al, 2008 tes the uom pilot project and potential is indeed worth thinking about. figure 2: pilot scale demonstration of biogas as a transport fuel at university of moratuwa conventional sources of energy and as fossil fuel supplies dry out the purchase costs are bound to rise and the country should be ready with technology options to serve energy needs of both as the standards of living improve and per capita income changes the to be always factored in. a biogas from external sources dry batch pit journal of tropical forestry and environment vol. 2, �o. 01 (2012) a pity that in sri lanka planners is oblivious to these opportunities with one technology an to pursue different pathways in fulfilling requirements in three different ways. a truly eu has shown in the light of climate change mitigation studies that is significant. ministry of science and technology supported study demonstrated the applicability in a local context with the use of a better gas 08, dilyana et al., 2010 tes the uom pilot project and potential is indeed worth thinking about. figure 2: pilot scale demonstration of biogas as a transport fuel at university of moratuwa conventional sources of energy and as fossil fuel supplies dry out the purchase costs are bound to rise and the country should be ready with technology options to serve energy needs of both as the standards of living improve and per capita income changes the to be always factored in. a biogas from external sources dry batch pit journal of tropical forestry and environment vol. 2, �o. 01 (2012) a pity that in sri lanka planners is oblivious to these opportunities with one technology an to pursue different pathways in fulfilling requirements in three different ways. a truly eu has shown in the light of climate change mitigation studies that is significant. ministry of science and technology supported study demonstrated the applicability in a local context with the use of a better gas , dilyana et al., 2010 tes the uom pilot project and potential is indeed worth thinking about. figure 2: pilot scale demonstration of biogas as a transport fuel at university of moratuwa conventional sources of energy and as fossil fuel supplies dry out the purchase costs are bound to rise and the country should be ready with technology options to serve energy needs of both as the standards of living improve and per capita income changes the to be always factored in. a biogas from external sources journal of tropical forestry and environment vol. 2, �o. 01 (2012) a pity that in sri lanka planners is oblivious to these opportunities with one technology an to pursue different pathways in fulfilling requirements in three different ways. a truly eu has shown in the light of climate change mitigation studies that is significant. ministry of science and technology supported study demonstrated the applicability in a local context with the use of a better gas , dilyana et al., 2010 tes the uom pilot project and potential is indeed worth thinking about. figure 2: pilot scale demonstration of biogas as a transport fuel at university of moratuwa conventional sources of energy and as fossil fuel supplies dry out the purchase costs are bound to rise and the country should be ready with technology options to serve energy needs of both as the standards of living improve and per capita income changes the to be always factored in. a biogas from external sources journal of tropical forestry and environment vol. 2, �o. 01 (2012) 1a pity that in sri lanka planners is oblivious to these opportunities with one technology an to pursue different pathways in fulfilling requirements in three different ways. a truly eu has shown in the light of climate change mitigation studies that is significant. ministry of science and technology supported study demonstrated the applicability in a local context with the use of a better gas , dilyana et al., 2010 figure 2: pilot scale demonstration of biogas as a transport fuel at university of moratuwa conventional sources of energy and as fossil fuel supplies dry out the purchase costs are bound to rise and the country should be ready with technology options to serve energy needs of both as the standards of living improve and per capita income changes the to be always factored in. a biogas from external sources -9 a pity that in sri lanka planners is oblivious to these opportunities with one technology an to pursue different pathways in fulfilling requirements in three different ways. a truly eu has shown in the light of climate change mitigation studies that is significant. ministry of science and technology supported study demonstrated the applicability in a local context with the use of a better gas , dilyana et al., 2010 figure 2: pilot scale demonstration of biogas as a transport fuel at university of moratuwa conventional sources of energy and as fossil fuel supplies dry out the purchase costs are bound to rise and the country should be ready with technology options to serve energy needs of both as the standards of living improve and per capita income changes the to be always factored in. at present first run a pity that in sri lanka planners is oblivious to these opportunities with one technology an to pursue different pathways in fulfilling requirements in three different ways. a truly eu has shown in the light of climate change mitigation studies that is significant. ministry of science and technology supported study demonstrated the applicability in a local context with the use of a better gas , dilyana et al., 2010 figure 2: pilot scale demonstration of biogas as a transport fuel at university of moratuwa conventional sources of energy and as fossil fuel supplies dry out the purchase costs are bound to rise and the country should be ready with technology options to serve energy needs of both as the standards of living improve and per capita income changes the t present first run a pity that in sri lanka planners is oblivious to these opportunities with one technology an to pursue different pathways in fulfilling requirements in three different ways. a truly eu has shown in the light of climate change mitigation studies that is significant. ministry of science and technology supported study demonstrated the applicability in a local context with the use of a better gas , dilyana et al., 2010 figure 2: pilot scale demonstration of biogas as a transport fuel at university of moratuwa conventional sources of energy and as fossil fuel supplies dry out the purchase costs are bound to rise and the country should be ready with technology options to serve energy needs of both as the standards of living improve and per capita income changes the t present first run a pity that in sri lanka planners is oblivious to these opportunities with one technology an to pursue different pathways in fulfilling requirements in three different ways. a truly eu has shown in the light of climate change mitigation studies that is significant. ministry of science and technology supported study demonstrated the applicability in a local context with the use of a better gas , dilyana et al., 2010). figure 2: pilot scale demonstration of biogas as a transport fuel at university of moratuwa conventional sources of energy and as fossil fuel supplies dry out the purchase costs are bound to rise and the country should be ready with technology options to serve energy needs of both as the standards of living improve and per capita income changes the t present the nation is a pity that in sri lanka planners is oblivious to these opportunities with one technology an to pursue different pathways in fulfilling requirements in three different ways. a truly eu has shown in the light of climate change mitigation studies that is significant. ministry of science and technology supported study demonstrated the applicability in a local context with the use of a better gas ). fig figure 2: pilot scale demonstration of biogas as a transport fuel at university of moratuwa conventional sources of energy and as fossil fuel supplies dry out the purchase costs are bound to rise and the country should be ready with technology options to serve energy needs of both as the standards of living improve and per capita income changes the the nation is a pity that in sri lanka planners is oblivious to these opportunities with one technology an to pursue different pathways in fulfilling requirements in three different ways. a truly eu has shown in the light of climate change mitigation studies that is significant. ministry of science and technology supported study demonstrated the applicability in a local context with the use of a better gas figure figure 2: pilot scale demonstration of biogas as a transport fuel at university of moratuwa conventional sources of energy and as fossil fuel supplies dry out the purchase costs are bound to rise and the country should be ready with technology options to serve energy needs of both as the standards of living improve and per capita income changes the the nation is a pity that in sri lanka planners is oblivious to these opportunities with one technology an to pursue different pathways in fulfilling requirements in three different ways. a truly eu has shown in the light of climate change mitigation studies that is significant. ministry of science and technology supported study demonstrated the applicability in a local context with the use of a better gas ure conventional sources of energy and as fossil fuel supplies dry out the purchase costs are bound to rise and the country should be ready with technology options to serve energy needs of both as the standards of living improve and per capita income changes the the nation is 3 a pity that in sri lanka planners is oblivious to these opportunities with one technology and to pursue different pathways in fulfilling requirements in three different ways. a truly eu has shown in the light of climate change mitigation studies that is significant. ministry of science and technology supported study demonstrated the applicability in a local context with the use of a better gas 2 conventional sources of energy and as fossil fuel supplies dry out the purchase costs are bound to rise and the country should be ready with technology options to serve energy needs of both as the standards of living improve and per capita income changes the the nation is de alwis/journal of tropical forestry and environment vol. 2, �o. 01 (2012) 1-9 4 totally ill-equipped to handle such an eventuality and are extremely susceptible to price and demand fluctuations. it is expected that industrialization to take us towards the status of a newly industrialised country. however, the existing industries face severe problems from their waste management practices and in turn lack a stable and a sufficient energy supply. the latter aspect is hindering industrial growth in several parts of the country. the industrial sector of sri lanka can hardly said to be in any way competitive. ♦ the environmental degradation in urban and semi-urban areas due to the generated solid waste is quite acute and is a growing problem with urbanization and population growth. we have not yet addressed this issue in a technically sound manner and the results from mismanagement is to be seen everywhere. it is important to realise that having vehicles to collect and transport for a final dumping site away from main stream view is not the final solution to the problem. the sewage generated is piped away to ocean outfalls in the city of colombo without any treatment. the individual septic systems are managed through gully bowser services when capacity exceeds or percolates slowly to the landmass with time. there is no recovery of energy from this potential waste organic scheme and contributes adversely to groundwater and water pollution. sea disposal is not being encouraged and contamination of fish can prove to be quite a problem as time passes. while country has to consider haacp certification for fish exports local population may have to be satisfied with sub standard feed having no other option. ♦ agriculture sector has many complaints due to rising fertiliser cost which has a direct effect on the profitability and the cost of produce. the escalating costs directly affect the consumer, which has severe economic consequences as this sector provides employment to a significant percentage. it is known that the consumer in sri lanka on average spends about 50-60% of his income on food and this is totally unacceptable. one way of reducing the burden is having a different source of ‘fertiliser’ input available. one major import to the country is urea and is heavily subsidised and this is mainly provide n to crops such as paddy. if one looks at these three problems and the wet biomass processing it is evident that the country stands to benefit from the triple advantages offered by the biogas option. • energy source – biogas is a clean energy source and can be enriched to natural gas quality • environmental management – solid and liquid waste conversion to biogas removes the organic waste burden • fertiliser / soil conditioner – from the residue left after anaerobic digestion and has enriched nitrogen in case of manure treatment it is indeed sad that the country has not exploited a technology, which is fast becoming quite a mature technology elsewhere (in germany in 2010, 2291 mwe (12.6% of renewable electricity) of national electricity was met through biogas and decentralised systems are quite common) to the best advantage of our nation. the diversion of the organic fraction of the solid waste (ofmsw) will entail work upstream which will help realising more resources to recycling as well as the technology will have a mechanical step in the front end of the technology. biogas extraction and use has become a vibrant industrial technology that is now finding applications due to variety of reasons in developed countries. some of these are essentially the problems faced today by developing countries as well. it is simply not possible for the developing economies to ignore the problems and seek solutions in another way; ♦ global climate change issues: uncontrolled methane emissions – as emitted from solid and liquid wastes of organic composition under anaerobic condition – are not acceptable today as methane is a powerful greenhouse gas (ghg). thus control of these emissions is essential from a climate change point of view. the solution that has been forwarded is the capture of this gas and utilise it via de alwis/journal of tropical forestry and environment vol. 2, �o. 01 (2012) 1-9 5 combustion thus converting it to co2 and obtaining energy as well. in addition land filling of municipal solid waste practiced by many developed economies now has brought in legislation prohibiting organic waste being land filled. this is again due to the methane emissions as landfill methane capture is not the most efficient and emissions can be quite problematic. ♦ conventional energy sources are depleting: the world has realised that there is only a finite time and that the time available is also short before conventional fuel resource base is depleted. thus the need to develop renewable energy resources have intensified and it is important to have proven, reliable and commercially viable energy systems available when the crunch occurs. it is not possible to develop new ways once the crisis is well set in. developed nations are locked in finding technological pathways and with renewables it is important to work with available resource bases. ♦ as a tool for sustainable development: today the emphasis is on sustainable development and both the way energy is used and the management of the environment have been given equal consideration. the potential of a good soil conditioner from biogas generation is another positive aspect. in satisfying these triple needs, biogas option provides a neat clean development mechanism. creating the environment for biogas in sri lanka the potential is clear but the paper does not provide hard numbers to clinch the case. there is a need to accept the common sense view that is sweeping many external industrialised nations. in such economies there is a need for migration as different systems are already in place and there is no incentive for immediate implementations. however the situation is different for sri lanka. thus policies must evolve to simultaneously support right hardware which then can lead to significant developments. at this juncture with regard to renewable energy systems application of conventional benefit-cost calculations may not mean much. a biogas system’s value as an environmental management technique is a key factor in utilising the technique across sectors such as the urban environment, industrial waste treatment and livestock and agriculture waste management facilities. the utilisation of a biogas system within these sectors will remove these places at least partially from the main energy supply chain. it is for this partial displacement that the country should be planning for initially. the promotion of biogas systems, based on raw materials such as animal waste and straw, have been largely targeted towards the rural household sector. despite practise since the 1970’s the success rate of these ventures has been low for many reasons. the findings of the national survey on biogas systems has been summarised in de alwis (2002). in developing countries, the promotion of biogas technology has been mainly directed towards this sector. in developed countries, the emphasis has been different. in developed economies, biogas technology has also been utilised successfully but in sectors such as industrial and urban waste treatment. quite large systems have come into commercial operation and cities such as stockholm are planning to switch to compressed biomethane for its transport fleet. these systems, known as high-rate units, will have higher initial technical inputs and necessitate different management systems. the type of digester systems used in these are high-rate units. high rate digestion is an improved mixed-phase digestion process in which the digester contents are maintained at 35-37°c and are completely mixed, enhancing digestibility of the substrate. most european reactors are operating at thermophilic range for higher efficiencies and as these countries face winters it is important for them to have more controlled digester systems. sri lanka can avoid thermophilic systems as the ambient mesophilic conditions are quite acceptable for hi-rate operations. there will be a requirement in slightly larger sizing as a result of lower rates of kinetics but this is not significant. de alwis/journal of tropical forestry and environment vol. 2, �o. 01 (2012) 1-9 6 a multi-step strategy (adopted from de alwis, 2001) it is evident that today there is a conducive climate both from policy perspective and in demonstrated technology for utilising biogas energy systems. however, to realise the biogas potential in sri lanka, several important developments are necessary to what is currently available. these should form essential steps in an overall strategy. (a) awareness of the problem (in terms of both energy and environment) and the consequent need for innovative solutions. there has to be policy initiatives in promoting these options available. however, the awareness should be more focused and detailed and it should be across the entire stakeholder group. one should move away from introducing basics (these activities definitely cannot be totally phased out) to more specific and detailed introductions. most of the times at present presentations on biogas is not going beyond simple introductions what? how and why? advantages and disadvantages etc. for an industry it is stated that normally 5m’s are required material, men, machinery, money and management. it is important to understand that the anaerobic digestion as an industry has to have one more m – microorganisms. the proper process understanding is essential. this has been ignored so far in the south. the south has been pre-occupied with a ‘container’ approach – always looking at varying the container as a way of reducing costs. the north has understood and implement the ‘process’ approach. today there is much more understanding of the microbial consortia responsible for anaerobic digestion across the multi-step process and improving efficiencies are possible. (b) it is quite important that research and data collection is carried out with the specific aim of biogas development. a more structured and a coordinated approach in research and development work is necessary and also data gathering had to be improved. these efforts will benefit many other developments as well. technology and the non-availability of industrial capital are the strongest drawbacks the country faces in developing renewables of this nature. one should identify the core engineering capabilities required in the promotion and the development and the quality aspects required in winning the hearts and the minds of the consumers. basic instrumentation in monitoring and analysers required in r&d are lacking and these need to be remedied. virtually connecting across research groups in sri lanka and with external networking much progress can be made. it is interesting to note that indiandrdo (defence research and development organisation)has claimed to successfully demonstrated biogas even in hilly colder regions today with working continuously on process development. (c) adoption of biogas systems in sewage handling (in the urban sector) should be promoted and developed. it is difficult at present to imagine sewerage systems coming into use widely. thus integrating functionally and aesthetically biogas systems into waste management and energy generation to household systems is necessary. wherever installing sewerage systems anaerobic digestion should form part of the overall objective of such systems. decentralised anaerobic systems can well come in urban sewage management. developing local area sewage networks is possible as truly to benefit with energy extraction a reasonable quantity of waste need to be present. (d) development of appropriate end-use mechanisms at both individual and institutional levels are necessary. the use of biogas for cooking may not meet with everyone’s satisfaction in the urban/rural environments. with miniaturised equipment available biogas units with gas cleaning may be even connected to household level transport fuel supply opportunities. household fuel cell systems are becoming available with biogas as the fuel feedstock. this demonstrates the extent to which different high end energy systems are coming into play today. (e) development of convenient digestion systems (the concrete/ brick masonry types are inappropriate as flexible or convenient systems). at household level one should look at incorporating a biogas system into the initial architectural planning. this type of popularisation using different materials is quite de alwis/journal of tropical forestry and environment vol. 2, �o. 01 (2012) 1-9 7 important in developing flexible systems for use. the manufacturing and fabricating capability should exist within the country. the necessary controls and instrumentation capabilities should also be built into these units designed for various utilisation contexts. a recent plastic biogas system developed locally is today available off-the-shelf for consumers and is a welcome development which can be further developed. (f) development of national standards for biogas systems at various levels of utilisation. slsi (sri lanka standards institute) is the relevant body. here information can be obtained and developed from indian and other european standards for different types of systems, appliances etc. the first sls standard for biogas systems for home based systems had been completed and launched (sls 1292:2006). the remaining two standards in the first phase are to cover the farm and institutional systems and industry based systems. lack of internal experiences is preventing the development of these standards at present. the developments in the latter two should be expedited. (g) emergence of private entrepreneurs with the ability to install and support biogas systems. for industrial systems it is possible to look at making the technology currently available externally, such as bioenergy (from biomechanics), bima (entech), anamet (ac-biotechnics), arrowbio (arrowecology), biofar (degremont), hyan (gore & storrie), dranco (organic waste systems) under licence to the local market. the market and monitoring mechanisms practised in nepal are of interest for small systems in sri lanka. the indian national master plan for biogas (2000-2005) offers a learning opportunity in technology transfer, adaptation and indigisation. a comprehensive review of biogas systems in the european union is provided in nynes and thomas s. (1998). it is important to note that kompogas (axpo kompogas ltd.) a plug flow biogas system won the 2002 energy globe award (the world awards for sustainability) and is another well-developed system. there is also the option of starting small and scaling up hi-rate biogas systems locally as the process mechanisms are known and it is not mandatory to source external process systems. scaling-up the system as developed by kularathne (2011) is quite feasible and this is the pathway to be taken when building internal capacity for technology. (h) since food and agro industries have the potential to dominate the sri lankan production and manufacturing sector, one can always envisage that if successful use of biogas systems is demonstrated, our emerging industries will stand to benefit from the knowledge base that will be readily available within the country. successes at the industrial sector level may in turn encourage the small scale use of low-rate systems at societal level. (i) more enlightened financing schemes should be set in place. indian ireda is an example. indians are utilising gef (global environmental facility) funds quite effectively in the development of biogas energy systems and there is a separate government ministry for non-conventional energy sources. thailand’s vspp (very small power producer) scheme (<1mwe) supported significant biogas systems development. sri lankan banks should be more enterprising and adopt and adapt different schemes for funding projects falling into these categories. it is important to realise that the present climate for renewable development is not exactly even a one of transition as the oil prices are at quite low levels and thus the technologies that have been developed have the edge over the developing technologies. however, the critical need for country’s development cannot be decided solely on the basis of a cost in rupees and cents and the government together with banks should understand this. any transition requires state to support and this support is evident within the world’s strongest economies. there are many technical options available for biogas energy systems though falling into few select categories in terms of technical definitions (i.e. low-rate, high-rate, fully mixed, plug flow etc). most projects –if not alltoday are guided by the conventional cost-benefit (ccb) analysis to guide investment decisions. the simple logic being, if the benefits of a project exceed the costs, the investments should be undertaken. as can be seen some thrust in development of biogas has occurred de alwis/journal of tropical forestry and environment vol. 2, �o. 01 (2012) 1-9 8 due to environmental reasons. these aspects are difficult if not impossible to identify and quantified and nor do they have proper market values. though non-market environmental valuation techniques are (evt) are available to carry out an extended benefit cost analysis perhaps it is much easier to utilise common sense and national policies of importance to devise mechanisms for development of these technologies. thus government intervention is necessary. this is true and applicable in developed countries as well as seen in united kingdom, australia and european union. germany has given quite favourable feed-in-tariff rates to encourage biogas electricity schemes which led to significant developments. (j) the most important factor is that the biogas production system should be considered in totality, rather than as a digester and a particular raw material – the systems approach. each aspect of the system should be equally supported (figure 3). figure 3: understanding the whole ‘system’ for successful utilization conclusion the proposed strategy is to promote biogas systems from a top down approach, i.e. from large/medium scale units to small scale units or from industrial/institutional systems to individual units. perhaps in the agriculture sector a more mixed approach is necessary. the biogas can and will be successful if there is enough emphasis on commercialisation and with the promotion of technologies through market mechanisms. the steps indicated should be the essential elements in the implementation strategy and should be in place to serve all levels of users. sri lankan policy planner should move away from looking at the biogas option mainly as a life-enhancing tool for the rural villager in a developing economy! and also from the view point that ‘high’ end technology is not for us!! it is unlikely and more of a certainty that biogas cannot serve as a cure for all energy, environmental and soil fertility problems of sri lanka. sri lanka should have sufficient energy, produced in an efficient manner, and in this biogas technologies can play a vital role as a steady state renewable energy supply operating in a decentralised form. much foreign exchange can be saved and external energy dependence reduced. improved technological competitiveness and competence resulting from this type of strategy will benefit other areas of our economy as well. de alwis/journal of tropical forestry and environment vol. 2, �o. 01 (2012) 1-9 9 one may conclude that there has never been a more important and an opportune time to develop viable renewable clean sustainable process technology system for sri lanka. the implementation process is challenging yet this is an opportunity that should not be wasted away. references barnett a., pyle l. and subramanian sk. 1978, biogas technology in the third world: a multidisciplinary review, idrc publication. chanakya n. hoysala. 2002. indian institute of science, bangalore, personal communication de alwis aap, solid waste management in sri lanka: a country perspective in solid waste management, grover vi, guha bk, hogland w, mcrae sg (eds), oxford & ibh publishing co. pvt ltd. pp 203-233, 2000. de alwis, a.a.p. 2002, biogas – a review of sri lanka’s performance with a renewable energy technology, energy for sustainable development, vol vi, no 1, pp 30-37. de alwis, a.a.p. 2002. industrial biomethanation practices for decentralized energy from waste: options for sri lanka in recovering energy from waste: various aspects, grover vi, grover vk and hogland w (eds), science publishers enfield usa, pp 151-165, 2002 de alwis, a.a.p. 2002. sri lanka: its industry and challenges in the face of climate change, chapter 18 in climate change: five years after kyoto, grover vi and grover vk (eds), science publishers, usa, pp 377-395, 2004. de alwis, a.a.p. 2001. study on the potential of biogas in sri lanka, renewable energy options – study 2, itdg-south asia publication. dilyana k.w.n., kularathne, m.a.d.i.c., rathnasiri, p.g., joseph, p.g. and de alwis, a.a.p. 2010. optimisation of an anaerobic co-digestion process and use of biomethane as a transport fuel, procs of the national energy symposiym, bmich, colombo pp 29-36. evans, g. 2005. biowaste and biological waste treatment, james & james (science pub.) ltd., london. kularathne, m.a.d.i.c. 2011. development of a pilot plant to demonstrate biogas as a transport fuel, msc thesis, dept of chemical and process engineering, university of moratuwa. kularatna, m.a.d.i.c., de alwis, a.a.p., and rathnasiri, p. g. 2008. review on upgrading and application of biogas as a vehicle fuel, procs of 14 th eru annual symposium, oct 15 th , faculty of engineering, university of moratuwa pp 36-37. mitzlaff, k. 1988.engines for biogas: theory, modifications, economic operation, friedr. vieweg & sohn braunschweig/wiesbaden, germany. nynes and thomas s. 1998.biogas from waste and wastewater treatment, cd from james & james uk. slsi, 2006. code of practice for design and construction of biogas systems part 1 – domestic biogas systems, sls 1292: 2006. vamathevan, k. 2011. the development of the process to synthesize carbon nanotubes from biogas, msc thesis, dept of chemical and process engineering, university of moratuwa. 64 use of wood characteristics in identification of selected terminalia species growing in sri lanka n.d. ruwanpathirana * state timber corporation, sampathpaya, rajamalwatte, battaramulla, sri lanka date received: 12-05-2014 date accepted: 11-07-2014 abstract 250 timber species are being used by the timber industry in sri lanka and among them building constructors, furniture manufacturers and wood fabricators are the main consumers. identification of the trees become very difficult once felled and processed and therefore macroscopic/ microscopic features and physical properties of timber become important. timber identification is necessary for right use of timber and to check on fraud in timber trading as some timber traders deceive customers by mixing low value timber with high quality ones. five timber species of terminalia namely t. arjuna (kumbuk), t. bellirica (bulu), t. catappa (kottamba), t. chebula (aralu) and t. parviflora (hampalanda) of the family of combretaceae were studied anatomically in search of sufficient features to separate one terminalia sp from the other. due to the resemblance of wood structure of five terminalia spp, examination of the transverse sections of wood with a hand lens (×25) does not provide adequate reliable information to differentiate one species from the other for identification. hence transverse section (t.s.), radial longitudinal section (r.l.t.) and tangential longitudinal section (t.l.s.) were obtained using the microtome for the anatomical examination. in this study, some important wood anatomical and non-anatomical features were studied according to iawa (1989). it was found that all terminalia spp had diffuse porous wood having vessels mainly solitary and occasionally in 2-3 of radial multiples. mean vessel diameter and vessel diameter range were recorded respectively as 241µm and 172-331µm in t. arjuna, 169µm and 107204µm in t. bellirica, 240µm and 169-309µm in t. catappa, 115µm and 68-175µm in t. chebula and 124µm and 75-159µm in t. parviflora. mean vessel frequency were observed as 3 per mm 2 in t. arjuna, 4 per mm 2 in t. bellirica, 3 per mm 2 in t. catappa, 6 per mm 2 in t. chebula and 5 per mm 2 in t. parviflora. mean rays frequency, mean ray height and mean ray width were found respectively as 9 per mm, 206µm, 24µm in t. arjuna, 11 per mm, 283µm, 24µm in t. bellirica, 8 per mm, 280µm, 25µm in t. catappa, 13 per mm, 239µm, 31µm in t. chebula and 10 per mm, 235µm, 30 µm in t. parviflora. ray cell arrangement is mostly uniseriate and occasionally biseriate in t. bellirica, t. parviflora and t. arjuna. ray cell arrangement is mostly multiseriate and occasionally uniseriate in t. catappa while t. chebula has uniseriate ray cell arrangement. * correspondence: nimalruwan@gmail.com tel: +94 112885853 issn 2235-9370 print/issn 2235-9362 online © university of sri jayewardenepura ruwanpathirana /journal of tropical forestry and environment vol. 4. no 02 (2014) 64-72 65 different type of axial parenchyma types were found in each terminalia species. t. bellirica had axial parenchyma band (more than three cells wide). t. parviflora and t. catappa had aliform/vasicentric type axial parenchyma which can be differentiated from confluent parenchyma type in t. chebula. vasicentric (halo) parenchyma types were found mainly in t. arjuna. finally, it can be concluded that ray cell arrangement and axial parenchyma types can be used together as baseline to distinguish terminalia spp in sri lanka for the purpose of timber identification. keywords: terminallia, wood structure, wood identification, xylem vessels, parenchyma 1. introduction terminalia is a pan tropical genus accommodating about 200 species (mcgaw et al., 2001). the genus terminalia is the second largest genus in the combretaceae which is distributed throughout the tropical and sub-tropical region of the world. the name terminalia derives from its latin name (terminalis=end) in accordance of the position of the leaves, which are crowded at the ends of shoots (lamb and ntima, 1971; rogers and verotta, 1996). terminalia spp range from small and medium sized shrubs or trees to large deciduous forest trees, ranging in height from 1.5 to 75 m tall (lebrum and stork 1991; schmidt et al., 2002). terminalia trees are planted in several countries in the tropics as a source of high quality solid timber for fine carpentry, joinery, building, flooring, plywood manufactures (schmidt et al., 2002; smith et al., 2004). the present investigation was carried out on five species of terminalia namely t. arjuna (kumbuk), t. bellirica (bulu), t. catappa (kottamba), t. chebula (aralu) and t. parviflora (hampalanda). this study mainly focused on variation of wood anatomy, specific gravity, wood texture and heartwood colour in search of anatomical features of any diagnostic importance for the identification of terminalia species. these five terminalia spp have been categorised in different classes in state timber corporation’s timber classification based on timber demand and its wood properties. t. arjuna and t. bellirica have been classified as special class and second class timber respectively. other terminalia spp like t. catappa and t. chebula were categorised under lower classes. the five terminalia species studied in this research work found some similar characteristics such as wood external appearance, some gross features and wood specific gravity. due to these reasons, authenticity of terminalia species is questionable when marketing logs or sawn timber. therefore the identification of these species by means of anatomical and other wood properties is imperative exercise to minimise various kinds of fraud taking place in timber industry. in addition this information is useful in timber utilisation aspect. jane (1967) recommended that the aspect of variation in wood structure is of practical importance in the industrial sense. he intended to draw the attention of wood anatomists engaged in wood quality study to look at the question of variability in wood structure. the structural features and variations in those features are related to properties and end uses. cell size and proportion and arrangement of the various types of elements and tissues, for example, tracheid, vessels, fibers, and parenchyma and of early wood and late wood, vertical elements and ray tissues determine the grain and figure. cell diameter in relation to cell wall thickness and the proportion of thin walled to thick walled cells determine density which is closely correlated to mechanical strength, machining and working properties and yield in pulping. the texture is concerned with the size of the wood element which depends mainly on the size of the vessel and the 66 size of the rays. texture is a compromise between vessel size and ray size. specific gravity which is the best single criterion of the strength of a piece of wood was also determined in order to make use in timber identification process. due to the above reasons, the present study was conducted (i) to examine the variation of wood anatomical features of the five terminalia species and (ii) to determine the specific gravity, wood color and wood texture of these five species. 2. materials and methods fresh timber disk with five cm thickness was cut at breast height of the mature tree in the field. a radial wood strip was cut from each disk and divided into upper and lower strips. one was used for the investigation of anatomical characteristics and the other for the measurement of specific gravity and heartwood colour. authentic timber samples of the five terminalia spp were collected from the research division of state timber corporation (stc) along with fresh wood samples. the collected specimens from two sources mentioned above, were anatomically compared with each other for confirmation of the identity. 2.1 determination of wood specific gravity a radial strip cut from each disk was used for the measurement of specific gravity. specific gravity was determined on the basis of oven-dry weight and green volume. specific gravity of terminalia species studied were grouped into three categories as basic specific gravity low ( 0.40), basic specific gravity medium (0.40-0.75) and basic specific gravity high (0.75). 2.2 wood color wood samples containing both heartwood and sapwood were used to determine wood color according to iawa (1989) category no. 197 to 202 by naked eye. heartwood color is categorised mainly into three groups namely (i) basically brown or shade of brown (ii) red or shade of red (iii) yellow or shade of yellow. visible differentiation of heartwood color from sapwood was also studied. 2.3 anatomical characteristics a radial strip taken from the pith to bark was used for the investigation of anatomical characteristics. so that the wood samples were boiled in water for about two hours to soften them. each wood sample was then shaped and sized into wood block of 2×2×3cm. transverse, radial and tangential sections at the range of 10-15 m thickness were obtained at the laboratory by using a sledge microtome (model leica sm2000 r). permanent slides of wood tissues were prepared after dehydrated and stained in safranin. sections were mounted using canada balsam using standard procedure. microscopic observations of each slide were made for qualitative and quantitative analysis of parameters under the light microscope at 4×10 magnifications. measurements on wood anatomical features were taken after photomicrographs of each slide were made by olympus microscope and micrometrics se premium 4 soft ware available in research division of stc. characters of wood anatomy for comparative anatomy were selected with the idea to use these parameters in timber identification with hand lens. vessel porosity, growth ring, vessel shape, vessel grouping, vessel arrangement were studied under the light microscope. mean tangential vessel ruwanpathirana /journal of tropical forestry and environment vol. 4. no 02 (2014) 64-72 67 diameter, vessel tangential diameter range and vessel frequency were then measured. measurement of vessel frequency was based on 10 counts in an area of 25mm 2 field of view. range of ray height, mean ray height, ray width and ray frequency were also studied. the measurement of ray frequency was based on 10 counts in a linear distance of 5mm field of view. the terminology and measurements were taken according to iawa committee (1989). visibility of vessels and rays on transverse section was also done with naked eye. these findings were grouped into fairly visible, just visible and not visible categories. 2.4 identification of wood texture mean vessel tangential diameter, ray width and ray height were measured for this purpose from which the average tangential diameter of the vessel (µm) was used to determine wood texture. although, vessel size is primarily responsible for texture, coarse texture may ensure from large rays alone in a wood with large rays and vessels of moderate size or small size. the table 1 and ray information given in table 4 are helpful to indicate roughly the basis of classification used in this study. table 1: classification of wood texture. type of wood texture average tangential vessel diameter (µm ) fine textured less than 100 microns medium textured 100 to 200 microns coarse textured more than 200 microns 3 results and discussion 3.1 heartwood and sapwood color of terminalia spp the sapwood from heartwood was easily distinguished in all the terminalia species used in this study. the colour of heartwood varied from yellow to brown in selected species. all the selected five terminalia species can be grouped into two categories according to heart wood colour. the yellow or shade of yellow colour heartwood was found only in t. bellirica. t. arjuna, t. catappa, t. chebula and t. parviflora bare brown or shade of brown heartwood. sap wood of t. parviflora was found as white to grey in colour. hence t. bellirica can be distinguished from other terminalia spp on the basis of heartwood colour. therefore heartwood color along with sapwood color can be used for the identification of terminalia spp. 3.2 wood texture t. arjuna, t. catappa and t. parviflora coarse wood texture and other species studied such as t. chebula and t. bellirica are medium textured wood. according to pearson and brown (1981) the other elements, especially where mass in zonate bands (parenchyma, fibers) must be taken into consideration to categorise wood texture. 3.3 specific gravity specific gravity determined in five species varied from 0.82 for t. arjuna to 0.63 for t. chebula (table 2). t. arjuna showed the highest mean specific gravity of 0.82, followed by t. parviflora (0.70), t. catappa (0.69), t. bellirica (0.66) and t. chebula (0.63). 68 five terminalia spp studied can be grouped into two groups according to iawa specific gravity classification, only t. arjuna was identified as high density wood. t. parviflora (0.7), t. catappa (0.69), t. bellirica (0.66) and t. chebula (0.63) were identified as medium density wood. iawa specific gravity classification of iawa is too broad to differentiate the terminalia species from each other because four terminalia spp fall into one specific gravity category. however, in the case of terminalia species verification process, specific gravity may be used as a parameter. table 2: variation of mean specific gravity, wood colour and wood texture in five terminalia species. species specific gravity kg/ m 3 at 12% m.c. color of heartwood (hw) and sapwood (sw) texture terminalia arjuna 0.820-high density hw colour darker than sw colour. hw basically brown or shades of brown coarse terminalia bellirica 0.660medium density hw colour darker than sw colour. hw basically yellow or shades of yellow medium terminalia catappa 0.690medium density hw colour darker than sw colour. hw basically brown or shades of brown coarse terminalia chebula 0.630-medium density hw colour darker than sw colour. hw basically brown or shades of brown medium terminalia parviflora 0.700-medium density hw colour darker than sw colour. sw is white to grey. hw basically brown or shades of brown coarse 3.4 anatomical properties vessels the anatomical features of terminalia species were shown in figure 1, 2 and table 3, 4. all selected species were diffuse-porous and growth ring boundaries were indistinct or absent except for t. arjuna which had inconspicuous distinct growth ring boundaries. vessels of all species were oval/round shape and majority was solitary and in radial rows of 2-3. vessel frequency in 25 mm 2 area varied as 163 in t. chebula to 70 in t. catappa (table 3). mean minimum vessel diameter and mean maximum vessel diameter were found as 96 µm in t. chebula and 241 µm in t. arjuna. vessels of t. chebula were not visible to naked eye. however, the vessels of t. arjuna, t. bellirica and t. catappa were easily visible at normal reading distance while t. parviflora is just visible to naked eye (table 3). this information can be used to distinguish t. chebula from other four species investigated. size of vessel is practicably useful anatomical property when timber is identified by a hand lens. ruwanpathirana (2002) found that vessel frequency and vessel size vary in radial direction from pith to bark in e. grandis. therefore this variation may effect to result of comparative wood anatomy if wood samples were not taken in a consistent manner in radial direction. ruwanpathirana /journal of tropical forestry and environment vol. 4. no 02 (2014) 64-72 69 figure 1: wood anatomical features of the genus terminalia. (a) cross section, (b) tangential longitudinal section, (c) radial longitudinal section of t. chebula; (d) cross section, (e) tangential longitudinal section, (f) radial longitudinal section of t. parviflora; (g) cross section, (h) tangential longitudinal section, (i) radial longitudinal section of t. belirica. axial parenchyma variations of axial parenchyma cells show significant difference among the selected species. more than three cells wide band of axial parenchyma was observed in t. bellirica. aliform and confluent axial parenchyma was found in t. arjuna, t. catappa and t. chebula. t. parviflora shows the vasicentric and alifom axial parenchyma. this variation of axial parenchyma is imperative to differentiate terminalia species in the process of timber identification. t. parviflora can be separated from other species because it does not have confluent or banded axial parenchyma and t. bellirica can be distinguished from other terminalia species because it is having banded axial parenchyma bands. rays rays were not visible to naked eye and the width of rays is less than half width of the vessel in all the selected terminalia species. ray cells are procumbent in all the species. among the all the studied species, uniseriate rays and rays which are mostly multiseriate, were found respectively in t. chebula and t. catappa. other terminalia species namely t. arjuna, t. bellirica (bulu) and t. 70 parviflora had mostly uniseriate and rarely bi-seriate. this ray characteristic can be used to differentiate t. chebula and t. catappa from other terminalia species. ray frequency per 5mm varied from 45 in t. arjuna to 65 in t. chebula. mean ray width varied from 23µm in t. arjuna to 31µm in t. chebula. this indicates that difference between ray widths within the five species is not enough for timber identification. variation of mean ray height from 206 µm to 300 µm was found in t. arjuna and t. parviflora respectively. when analyzing this results, it is understandable that mean ray height, mean ray width and ray frequency cannot be used comfortably for timber identification. (figure 1, 2 and table 4). table 3: variation of growth ring, vessel porosity, vessel arrangement, vessel grouping, vessel shape, vessel deposit, vessel diameter range, mean vessel tangential diameter and axial parenchyma in five terminalia species. species growth ring, vessel porosity, vessel arrangement, vessel grouping, vessel shape and vessel deposit. vessel diameter range (mean vessel diameter)µm vessels in 25mm² axial parenchyma terminalia arjuna growth ring boundary distinct but inconspicuous, diffuse –porous, diagonal and / or radial rows of 2-4 (mostly 2-3) and majority exclusively solitary ,oval shape and tyloses common 172-331 (241) easily visible at normal reading distance. 74 axial parenchyma vasicentric (mainly), aliform and confluent terminalia bellirica growth ring boundary indistinct or absent, diffuse –porous, the majority solitary and in radial rows of 2-4 (mostly 2-3), oval shape. occasional brownish-yellow gum present. 107-204 (169) easily visible at normal reading distance. 92 axial parenchyma, aliform, confluent and mostly bands more than thee cells wide. terminalia catappa growth ring boundary indistinct or absent, diffuse –porous, the majority solitary and in short radial rows of 2-4 (mostly 2-3). oval shape and occasional brownish-yellow gum present. 169-309 (240) easily visible at normal reading distance 70 axial parenchyma vasicentric, aliform and occasionally confluent. terminalia chebula growth ring boundary indistinct or absent, diffuse –porous, the majority solitary and in short radial rows of 2-4 (mostly 2-3). oval shape and occasional yellowish brown gum present. 68-126 (96) not visible to naked eye 163 axial parenchyma aliform and mostly confluent. terminalia parviflora growth ring boundary indistinct or absent, diffuse –porous, the most solitary and in short radial rows of 2-3 occasionally. oval/round shape. 75-159 (124) just visible to naked eye 135 axial parenchyma vasicentric and aliform. ruwanpathirana /journal of tropical forestry and environment vol. 4. no 02 (2014) 64-72 71 figure 2: wood anatomical features of the genus terminalia. (a) cross section, (b) tangential longitudinal section, (c) radial longitudinal section of t. catappa; (d) cross section, (e) tangential longitudinal section, (f) radial longitudinal section of t. arjuna. table 4: variation of ray width, ray width range (µm), mean ray width (µm), ray height range (µm), mean ray height (µm), rays per 5mm for five terminalia species. species ray width (µm) ray width range & mean width (µm) ray height range& mean height (µm) rays per 5 mm terminalia arjuna not visible to naked eye. less than half width of the pore. ray mostly uniseriate, rarely bi-seriate. 13-36 (23) 75-448 (206) 45 terminalia bellirica not visible to naked eye .less than half width of the pore. ray mostly uniseriate and rarely biseriate. 13-42 (30) 166-440 (265) 55 terminalia catappa not visible to naked eye. less than half the width of the pore. mostly multiseriate. 9-39 (23) 217-374 (291) 40 terminalia chebula not visible to naked eye. less than half width of the pore. uniseriate. 19-46 (31) 114-491 (239) 65 terminalia parviflora not visible to naked eye .less than half width of the pore. ray mostly uniseriate and rarely biseriate. 20-44 (30) 139-357 (300) 50 4. conclusion among the studied anatomical properties, ray cell arrangement and axial parenchyma type showed comparative differences within studied terminalia spp. ray cell arrangement was mostly uniseriate and occasionally biseriate in t. bellirica, t. parviflora and t. arjuna. ray cell arrangement is mostly multiseriate and occasionally uniseriate in t. catappa. t. chebula has uniseriate ray cell arrangement. therefore t. chebula and t. catappa can be distinguished. 72 different types of axial parenchyma types were found in each terminalia species from which the prominent type of axial parenchyma was identified from each species as follows. t. bellirica had axial parenchyma band (more than three cells wide). t. parviflora and t. catappa had aliform/vasicentric type axial parenchyma which can be differentiated from confluent parenchyma type in t. chebula. vasicentric (halo) parenchyma types were mainly found in t. arjuna. other than ray and parenchyma cells, vessel diameter can be used to differentiate t. arjuna (larger vessel) from t. parviflora. finally, it can be concluded that ray cell arrangement, axial parenchyma types and in addition vessel diameter can be used together as baseline information to distinguish terminalia spp in sri lanka for the purpose of timber identification. acknowledgement the chairman, board of directors and general manager of state timber corporation (stc) are acknowledged for providing facility to conduct this study. further, the staff of the research, development and training division of the stc is also acknowledged. references iawa committee, 1989. iawa list of microscopic features for hard wood identification, iawa bulletin (n.s.) 10, the netherlands. jane, f.w. 1967. the microscopic examination of woody materials, watsons’s micro, rec. lamb, a.f.a. and ntima, o.o. 1971. terminalia ivorensis; fast growing timber trees of the lowland tropics: no.5. commonwealth forestry institute, oxford, uk. lebrum, j.p. and stork, a. 1991. enumeration des plantes a fleurs d ‘afrique tropicale. mcgaw, l.j., rabe, t., sparg, s.g., jager, a.k., eliff, j.n. and van staden, j. 2001. an investigation on the biological activity of combratum spp. journal of ethnopharmacology, 75: 45-50. rogers, c.b. and verotta l. 1996. chemistry and biological properties of the african combretaceae ruwanpathirana, n.d. 2002. variation of some wood properties of eucalyptus grandis and pinus caribaea in different site classes. ph.d. thesis, university of ruhuna, sri lanka. ruwanpathirana, n.d. 2012. sustainable utilization of timber resources in sri lanka. soba, ministry of environment, sri lanka, pp.56-70. schmidt, e., lolter, m. and mccleland, w. 2002. trees and shrubs of the mpumalanga and kruger national park. jacana publisher, johannesburg. smith, n., scott, a.m., henderson, a., stevenson, d.w.m. and scott, v.h. 2004. flowering plants of the tropics, princeton university press. princeton, new jersey. microsoft word 3 kuruppuarachchi final edited kuruppuarachchi et al., /journal of tropical forestry and environment vol. 3, no. 01 (2013) 17-23 17 drought induced fine root growth and canopy green-up of tropical dry zone vegetations in sri lanka k. a. j. m. kuruppuarachchi 1* , g. seneviratne 2 and b. d. madurapperuma 3 1 department of botany, the open university of sri lanka, nawala, nugegoda, sri lanka 2 microbial biotechnology unit, institute of fundamental studies, kandy, sri lanka 3 environment and conservation science program, north dakota state university, p. o. box 6050, fargo, nd58108, usa date received: 24-11-2012 date accepted: 18-02-2013 abstract fine roots in forest soils have important implications for global carbon (c) balance, but processes underlying this c sink are not well understood. this study evaluates year round dynamics of fine roots in a tropical dry mixed evergreen forest and an arboretum in the dry zone of sri lanka. monthly soil core samples (up to 25 cm depth) were collected randomly to cover a whole annual cycle of the two sites. the soils were air dried, sieved (< 2 mm), and fine roots (≤ 2 mm) were separated by handpicking coupled with a water floating technique. then, fine root biomass and c density were calculated using oven dry weight. annual mean fine root biomass of the dry zone forest and the arboretum were found to be 5.72 ± 0.57 t/ha and 7.88 ± 0.81 t/ha, respectively, with c densities of 2.69 ± 0.27 t/ha and 3.7 ± 0.38 t/ha, respectively. thus, dry zone arboretum showed a higher growth and biomass, and hence a c pool of fine roots, than the dry zone forest, possibly due to a younger forest stand with fast fine root turnover rate. in both sites during the dry spell, there was an increased production of fine roots and a simultaneous leaf flush on the canopy with a green-up. the increased fine root growth during the dry season generally allows the trees to absorb more water under water-stressed situations. these events may be due to an undisclosed survival mechanism of such ecosystems under drought, which needs further studies. key words: drought, fine root growth and canopy green-up, tropical dry zone vegetation 1. introduction fine roots (diameter < 2 mm) have important implications for the global c balance, but the processes underlying this c sink are not well understood (vargas and allen, 2008). although fine roots represent only a small fraction (ca. 5%) of the total tree biomass, they can consume about 30 to 50% of the annual primary production (jackson et al., 1997) and are a major contributor to organic matter and mineral nutrient cycles. other functions of fine roots include anchorage, absorption of water, and synthesis of various essential compounds such as growth regulators (upadhaya et al., 2005). *correspondence: kajmkuruppu@gmail.com tel: +94 (011) 288 1269; fax: +94 (011) 243 6858 issn 2235-9370 print / issn 2235-9362 online ©2013 university of sri jayewardenepura kuruppuarachchi, et al. /journal of tropical forestry and environment vol. 3, no. 01 (2012) 20-26 18 fine roots, existing as a root mat in the surface soil, are a common feature of tropical forests. they act as a safety net for conserving soil nutrients (seneviratne et al., 2006). fast growth and turnover of fine roots make the fine root system a dynamic component of the forest c cycle (rasse et al., 2005). fine root biomass is an important parameter related to c allocation and turnover at the ecosystem level (jackson et al., 1997; nepstad et al., 1994). jackson et al. (1997) estimated that globally, about 20 gt c is stored in living fine roots. about 30% of that is contained within tropical forests. factors such as soil temperature, moisture, and nutrient availability control growth and turnover of fine roots (pregitzer, 2002). hence, forest floor litter accumulation plays an important role in growth and turnover of fine roots. therefore, there is an annual pattern of fine root dynamics that regulates soil c turnover and sequestration. to understand soil c sequestration of the forest ecosystems, it is thus necessary to conduct detailed studies of fine roots with extensive sampling. the dry zone of sri lanka represents 80% of its land mass (perera, 2001). eighty percent of the dry zone is covered by forests, which are called “secondary old climax vegetations” or “dry mixed evergreen forests” (dittus, 1985). thus, the dry zone plays an important role in the c sequestration. however, there are no proper studies conducted to investigate fine root dynamics in the dry zone. therefore, the present study was planned to examine the annual growth pattern of fine roots in the dry zone vegetations of sri lanka. 2. materials and methods 2.1. study sites representative sampling sites were selected from a dry zone forest (sigiriya sanctuary) and a dry zone arboretum of sri lanka. the arboretum, which represents a dry-mixed evergreen forest (cramer, 1993) was selected, because we were interested to know how close a silviculturally-managed forest to a natural forest for supporting c sequestration. although, a natural forest corresponds to an old growth forest, a silviculturally managed forest also represents a closed canopy with high species composition similar to a natural forest (cramer, 1993; perera, 2001; dilhan, 2006).thus, we assumed that the light penetration to the forest floor and soil temperature between the two sites are comparable. it is reported that fine root growth is governed by soil temperature when it fluctuates sharply during day and night with night temperatures below 17 o c, but soil moisture becomes the determinant factor above that temperature (teskey and hinekley, 1981; pregitzer et al., 2000). thus, in dry tropical forests in general, soil moisture is considered to be the determinant of fine root growth (yavitt and wright, 2001). study sites with similar slope (almost flat terrain at 185 – 215 m elevation) were selected from both sites. the sanctuary surrounds the ancient rock fortress of sigiriya, an archeologically important world heritage site at 150 m altitude. in the 1990’s, it was declared a sanctuary with 5,099 hectares (green, 1990). it is composed of understory plants (< 10 cm dbh) of 81 species representing 73 genera and 37 families (solangaarachchi and perera, 1993). the canopy of the forest is somewhat discontinuous and approximately 15-18 m in height. sigiriya sanctuary is a secondary naturalized forest due to “swidden” agriculture (perera, 2001). the initial soil properties of sigiriya sanctuary were recorded during the dry spell of 2007 by kuruppuarachchi (2011) as, soil temperature (25-32 o c), moisture (10.04% ± 4.5), ph (6.19 ± 0.38), soil organic carbon (1.48 % ± 0.25), total n (0.10% ± 0.02), nh4 + -n (0.03 µg/g soil ± 0.01), no3 -n (0.182 µg/g soil ± 0.01), and bulk density (1.40 g/cm 3 ± 0.28). the arboretum (5º 54ˈ n 9º 52ˈ n and 79º 39ˈ e 81º 53ˈ e) is situated in dambulla, which is located in the dry heartland of sri lanka. this is the only dry zone arboretum in sri lanka that is used as a living museum, a shelter for tropical trees that provides refuge for wildlife (dilhan et al., 2010). the arboretum was silviculturaly managed to form a natural forest. the arboretum is covered by different vegetation types such as dry mixed evergreen forest, woodland, and scrubland. the variety of habitats contributes to increased biodiversity of the arboretum, comprising 192 plant species, 72 bird species and kuruppuarachchi et al., /journal of tropical forestry and environment vol. 3, no. 01 (2013) 17-23 19 35 types of butterflies (cramer, 1993; dilhan et al., 2010). the initial soil properties of the arboretum were recorded during the dry spell of 2007 by kuruppuarachchi (2011) as, soil temperature (25-32 o c), moisture (10.22% ± 1.16), ph (6.26 ± 0.04), soil organic carbon (1.40 % ± 0.05), total n (0.10% ± 0.005), nh4 + -n (0.03 µg/g soil ± 0.04), no3 -n (0.16 µg/g soil ± 0.05), and bulk density (1.36 g/cm 3 ± 0.15). 2.2. sampling a plot of 20 m x 20 m was demarcated in the two sites for sampling. monthly, twenty soil core samples, to a depth of 25 cm, were taken randomly to cover a whole annual cycle from january to december 2007. then, the samples were air dried and sieved (< 2 mm). fine roots (≤ 2 mm diameter) on the sieve were handpicked. fine roots in < 2 mm soil fraction were collected using a magnifying glass. very fine root fraction was separated by the water floating technique (anderson and ingram, 1998). then, all the fine root fractions were amalgamated and oven dried at 60 o c to a constant weight (hodge et al., 2000). total fine root biomass was calculated as a percentage of soil weight using the following equation. density of fine root biomass was calculated as root weight per square meter using soil bulk density, and c density was considered as 50% of fine root density (ipcc, 2006). fine root biomass and c density were expressed as weight in tons per hectare. fine root biomass (%) = (oven-dried fine root weight/oven-dried (105 o c) soil weight) × 100 fourier transform infrared spectroscopy (ftir) spectra were obtained of kbr pellets, formed by the dried soil samples with kbr 1 to 50 ratios. the pellet was analyzed under 4000-400 cm -1 wave number range with a resolution of 4 cm -1 . each spectrum was composed of 64 scans coded before fourier transforms processing. the omnic © version 6.1 windows (thermo nicolete corp.) on the reduced portions of the spectra (4000-400 cm -1 ) was used. ftir peaks representing different chemical bonds of active groups in natural molecules were identified using the software and literature (lammers et al., 2009; celi et al., 2010). 3. results and discussion annual mean fine root biomass of the dry zone forest and the arboretum were found to be 5.72 ± 0.57 t/ha (2.69 ± 0.27 tc/ha), 7.88 ± 0.81 t/ha (3.70 ± 0.38 tc/ha), respectively. the average standing fine root biomass (0-50 cm depth) in global tropical forests has been reported to be 4.51 ± 0. 45 t/ha (hertel and leuschner, 2005), and it increases with the altitude (cairns et al., 1997). however, in amazonian forests, fine root growth up to 8.06 t/ha has been reported (cuevas and medina, 1988), which is comparable with our study. generally, root biomass can differ largely between stands depending on tree species, soil conditions, and profile depth. the higher fine root growth, particularly in the arboretum, may be due to silvicultural management of the site, which has contributed to comparatively higher fine root c sequestration. maximum fine root growth was observed during the dry spell in august in both sites (fig. 1). this allows the trees to absorb more water from water stressed soil. nutrients required to grow the roots during the drought were likely supplied from the decomposition of soil labile c, as reflected by the reduction of the c fraction (aliphatic c–h vibration peaks at 2924 cm −1 ) in the ftir spectral data (fig. 2). with the commencement of rain in september, the root biomass started to drop sharply due to decomposition in the dry zone forest, but not in the arboretum. fresh c leaching to the sub soil from the decomposing fine roots, as well as the floor litter layer (fontaine et al., 2007) during the rainy period of the dry zone forest, has apparently contributed to the decomposition of stable c fractions (aromatic c-h ,vibration peaks at 1618 cm -1 and 3414 cm -1 ), as evident from the ftir spectral data. in january, there was a relatively high fine root biomass in the arboretum compared to the dry zone forest. kuruppuarachchi, et al. /journal of tropical forestry and environment vol. 3, no. 01 (2012) 20-26 20 figure 1: fine root biomass dynamics of the dry zone forest and the arboretum during january to december 2010. vertical bars show standard errors. figure 2: ftir spectra of soils collected during dry and rainy periods of the dry zone forest. thick and thin lines of the spectrum represent dry and rainy periods, respectively. %t is the percentage transmittance. the fine roots occurring mainly in the upper soil horizons represent the most dynamic part of the root system (cairns et al., 1997). roots can respond to both internal and external controls such as kuruppuarachchi et al., /journal of tropical forestry and environment vol. 3, no. 01 (2013) 17-23 21 temperature and water availability. fine root longevity depends on species, climate, and soil conditions and can range from weeks to several years. however, factors controlling root dynamics are still poorly understood (hendrick and pregitzer, 1996). from the satellite data, it was observed that there was a leaf flush with canopy green-up in the dry zone forest (figure 3).however, in the arboretum a leaf flush was not visible due to small size of the site. an unusual above ground leaf flush has also been observed in amazon forests in an extreme drought (berlin et al., 2000; saleska et al., 2007). pau et al. (2010) have also identified hawaiian rainforest greenup in responses to seasonal and el niño-driven droughts. nutrients required to grow the canopy during the drought may also have been supplied from the soil labile c decomposition, as mentioned above. figure 3: canopy of the sigiriya dry zone forest during the dry spell. light green color patches on the canopy are the new flush. high spatial resolution images were acquired from google maps and google earth (source: http://maps.google.com). references anderson, j.m., and ingram, j.s.i. 1998. tropical soil biology and fertility: a handbook of methods, second ed. cabi international, uk. berlin, k.e., pratt, t.k., simon, j.c., kowalsky, j. r., and hatfield, j.s. 2000. plant phenology in a cloud forest on the island of maui. biotropica 32: 90-99. cairns, m.a., brown, s., helmer, e.h., and baumgardner, g.a. 1997. root biomass allocation in the word upland forests. oecologia 111: 1-11. celi, l., rosso, f., freppaz, m., agnelli, a., and zanini, e. 2010. soil organic matter characteristics in sporadic permafrost-affected environment (creux du van, switzerland). arctic, antarctic, and alpine research 42:1-8. cramer, l.h. 1993. a forest arboretum in the dry zone. institute of fundamental studies, kandy, sri lanka. cuevas, e., and medina, e. 1988. nutrient dynamics within amazonian forests. ii. fine root growth, nutrient availability and leaf litter decomposition. oecologia 76: 222-235. dilhan, m.a.a.b., amarasinghe, j., and wijewardene, d.n.n. 2010. building sustainable botanic gardens: a simple silvicultural method adopted to haven certain wood trees into productive arboretum in the dry zone of sri lanka.proceedings of the fourth global botanic gardens congress, dublin, kuruppuarachchi, et al. /journal of tropical forestry and environment vol. 3, no. 01 (2012) 20-26 22 ireland, 1-4. http://www.bgci.org/files/dublin2010/papers/dilhan-m-a-a-b.pdf. access 01 december 2010. dilhan, m.a.a.b., weerasinghe, t.d. and amarasinghe, j. 2006. structure and composition of vegetation in the ifs popham arboretum, dambulla. wildlanka 1:90-102. dittus, w.p.j. 1985. the influence of leaf-monkeys on their feeding trees in a cyclone-disturbed environment. biotropica 17: 100-106. fontaine, s., barot, s., barré, p., bdioui, n., mary, b., and rumpel, c. 2007. stability of organic carbon in deep soil layers controlled by fresh carbon supply. nature 450: 277-280. green, m.j.b. 1990. iucn directory of south asian protcted areas. iucn, cambridge, u.k. hendrick, r.l., and pregitzer, k.s. 1996. applications of minirhizotrons to understand root function in forests and other natural ecosystems. plant and soil 185: 293-304. hertel, d., and leuschner, c.h. 2005. fine root mass and fine root production at tropical moist forests as dependent on soil, climate and elevation. in: bruijnzeel, l.a., and juvik, j. (eds.), mountains in the mist: science for conserving and managing tropical montane cloud forests, hawaii university press, pp. 208-216. hodge, a., stewart, j., robinson, d., and fitter, a.h. 2000. competition between roots and soil microorganisms for nutrients from nitrogen-rich patches of varying complexity. journal of ecology 88: 150-164. ipcc, 2006. ipcc guidelines for national greenhouse gas inventories. in: eggleston, h.s, buendia, l., miwa, k., ngara, t. and tanabe, k. (eds.), prepared by the national greenhouse gas inventories programme, institute for global environmental strategies, ippcc, hayama, japan. jackson, r.b., mooney, h.a., and schulze, e.d. 1997. a global budget for fine root biomass, surface area, and nutrient contents. proceedings of the national academy of sciences 94: 7362-7366. kuruppuarachchi, k.a.j.m. 2011. carbon sequestration as influenced by climatic, plant and soil parameters, their dynamics and control of selected sri lankan forests. doctor of philosophy dissertation, faculty of natural sciences, the open university of sri lanka. lammers, k., arbuckle-keil, g., and dighton j. 2009. ftir study of the changes in carbohydrate chemistry of three new jersey pine barrens leaf litters during simulated control burning. soil biology and biochemistry 41: 334-340. nespstad, d.c., carvalho, c., davidson, e., jipp, p.h., lefebvre, p., negreiros, g.h., da silva, e.d., stone, t.a., trumbore, s.e., and vieira, s.a. 1994. the role of deep roots in the hydrological and carbon cycles of amazonian forests and pastures. nature 372: 666-669. pau, s., okin, g.s., and gillespie, t.w. 2010. asynchronous response of tropical forest leaf phenology to seasonal and el niño-driven drought. plos one 5(6): e11325. doi:10.1371 /journal.pone.0011325. perera, g.a.d. 2001. the secondary forest situation in sri lanka: a review. journal of tropical forest science 13: 768-785. pregitzer, k.s., king, j.s., burton, a.j., and brown, s.e. 2000. response of tree fine roots to temperature. new phytologist 147: 105-115. pregitzer, k.s., 2002. fine roots of trees – a new perspective. new phytologist 154: 267-270. rasse, d.p., rumpel, c., and dignac, m.f. 2005. is soil carbon mostly root carbon? mechanisms for a specific stabilization. plant and soil 269: 341-356. saleska, s.r., didian, k., huete, a.r., and da rocha, h.r. 2007. amazon forests green-up during 2005 drought. science318(5850): 612. seneviratne, g., kuruppuarachchi, k.a.j.m., somaratne, s., and seneviratne, k.a.c.n. 2006. nutrient cycling and safety-net mechanism in the tropical home gardens. international journal of agricultural research 1: 169-182. solangaarachchi, s.m., and perera, b.m.s. 1993. floristic composition and medicinally important plants in the understory of the tropical dry mixed evergreen forest at the hurulu reserve of sri lanka. journal of national science council sri lanka 21(2): 209-226. kuruppuarachchi et al., /journal of tropical forestry and environment vol. 3, no. 01 (2013) 17-23 23 teskey, r.o., and hinekley, t.m. 1981. influence of temperature and water potential on root growth of whiteoak. physiologia plantarum 52: 363-369. upadhaya, k., pandey, h.n., law, p.s., and tripathi, r.s. 2005. dynamics of fine and coarse roots and nitrogen mineralization in a humid subtropical forest ecosystem of northeast india. biology and fertility of soils 41: 144-152. vargas, r., and allen, m.f. 2008. dynamics of fine root, fungal rhizomorphs, and soil respiration in a mixed temperate forest: integrating sensors and observations. vadose zone journal 7: 1055-1064. yavitt, j. b., and wright, s.j. 2001. drought and irrigation effects on fine root dynamics in a tropical moist forest, panama. biotropica 33: 421-434. iyekekpolor and balogun/ journal of tropical forestry and environment vol. 10 no. 01 (2020) 75-86 _____________________________________________ *correspondence: francis.balogun@uniben.edu tel: +23 48057378533 ©university of sri jayewardenepura 75 a geospatial assessment of deforestation of sokponba and ehor forest reserves in edo state a.c. iyekekpolor and t.f. balogun* department of geography and regional planning, university of benin, benin city, nigeria date received: 09-02-2020 date accepted: 25-06-2020 abstract the study assesses the state of sokponba and ehor forest reserves in edo state, with landsat images of 1987, 2002 and 2018 using envi and arcgis software. questionnaire was also administered to elicit information from respondents. the study reveals that within the period of 31 years under study sokponba forest reserve has reduced from 28,913.63 ha in 1987 to 1,578.15 ha in 2018 while plantation and farmland increased from 15,357.96 ha in 1987 to 43,494.21 in 2018. ehor reserve also reduced from 11,128.86 ha in 1987 to 3,242.28 in 2018. in the same vein, plantation and farmland increased from 1,424.97 ha in 1,987 to 9,323.28 ha in 2018. the deliberate government policies of allocating compartment to timber contractors for logging, conversion of reserves to oil palm plantation and farmland were identified as the major drivers responsible for the depletion of the forest reserves. considering the consequential effects arising from deforestation such as carbon sequence, greenhouse effect (global warming) and flooding the study recommends reforestation and taungya farming system for sustainable environment. keywords: reserves, geospatial, deforestation, global warming, reforestation 1. introduction forest reserves are areas of forest designated by the government for the protection of trees growing or planted in order to preserve a particular type of habitat and its flora and fauna which are often considered rare or endangered (usman and adefalu, 2010; farlex, 2014). forest reserves are thus areas of forests which are reserved and managed for conservation and to provide special opportunities for study or research. according to oyebo (2006), nigeria has a total of 1,160 constituted forest reserves, covering a total land area of 10, 752,702 ha, representing about 10% of the total land area. forests, according to food and agriculture organization (2010), provide support for one billion people that live in extreme poverty around the world and provide remunerative employment to more than one hundred million. they contain more than 80% of terrestrial biodiversity and provide essential environmental services such as soil conservation, water shed management, protection against floods and landslides, sources of industrial woods (aweto, 1990; ojonigu et al., 2009) effective sink for carbon dioxide and release of oxygen (oduntan et al., 2012). despite these benefits, forests are currently under severe human interference which is distorting its natural state and impacting negatively on the biodiversity composition and the environment. the continued indiscriminate cutting down of trees without replacement for constructions, fuel wood, agricultural purpose, grasing and hunting, has led to the degradation of the forest ecosystem, extinction of valuable trees, wildlife and loss of biodiversity. cullen et al. (2011) are of the view that at least 18% of global greenhouse (ghg) emissions, a major cause of climate change worldwide is attributable to deforestation. doi: https://doi.org/10.31357/jtfe.v10i1.4690 76 fao (2010) further observed that in africa, nigeria is among the five countries with the largest annual net loss of forest for 2000-2010, with 3.7%. the situation has not changed. between the periods of 2005 to 2010, about 410,100 ha of forest was lost per year. (batta et al., 2013) observed that nigeria has one of the largest rates of deforestation in the world; the country has lost 55.7% of its primary forest. olakunle et al. (2011) opined that the main drivers of deforestation in the country are agriculture, logging and mining. considering the alarming rate of forest depletion in nigeria and the consequential effect of global warming and flooding, it becomes paramount to monitor our forest reserve in nigeria. this paper therefore assesses the state of sokponba and ehor forest reserves using satellite data and questionnaire survey to determine the driver responsible for forest depletion in nigeria. 2. methodology 2.1 the study area two forest reserves, sakponba forest reserve in orhionmwon lga and ehor forest reserve in uhunmwonde lga were selected out of 23 forest reserves in edo state for detailed study (figure 1). sokponba forest reserve was constituted in 1912 while ehor forest reserve was constituted in 1950. sokponba reserve covers an area of 49,210 ha while ehor covers a total area of 29,566 ha. the total area coverage of the forest reserves under study is put at 78,776 ha. the sokponba forest reserve is located between latitude 6°12 / 10.49 // n and 5°58 / 15.29 // n and between longitude 5°49 / 46.42 // e and 5°52 / 11.63 // e. while the ehor bc16/1 forest reserve spans between latitude 6°23 / 33.89 // n and 6°26 / 10.38 // n and longitude 5°57 / 55.42 // e and 6°6 / 6.59 // e. sokponba forest reserve has 176 compartments, and ehor bc16/1, 114 compartments. there are several villages in and around the forest reserves areas. figure 1. forest reserves in edo state. iyekekpolor and balogun/ journal of tropical forestry and environment vol. 10 no. 01 (2020) 75-86 77 sokponba and ehor forest reserves are tropical rainforest, rich in economic valuable trees such as opepe, afara, mahogany, albizia, alstonia, okwen and several others which are made up of three layers with a close canopy. these forests serve as source of income generation to the government, communities and individuals, through lumbering, logging and farming activities taking place in the forest. the socio-economic activities of the communities in the study areas is mainly subsistence farming. crops such as cassava, yams, plantain are cultivated. 2.2 data collection all the works reviewed i.e., foody (2003), fearnside et al. (2004), kumar et al. (2010), ati et al. (2010), naemi et al. (2011), dewan et al. (2012), akingbogun et al. (2012), aliyu et al. (2012), yohanna et al. (2012), njungbwen et al. (2013), okeke (2013), reddy et al. (2013), krishna et al. (2014), nmom et al. (2014), adedeji et al. (2015) utilised geospatial techniques and their results indicated decrease in forest resources due to anthropogenic activities but one of the studies involved human dimension in the method of assessment of the state of the forest. since man was responsible for deforestation and also at the receiving end, this study combines both remote sensing technique and questionnaire survey method in the research design. multi-temporal landsat images of 1987, 2002 and 2018 of the study areas, with a resolution of 30 and 28.5 metres were used. repeated visits to the study area was carried so as to have adequate knowledge of the prevalent and dominant land cover and land use types. this enabled accurate land use and land cover classification. snowball sampling technique was employed in the administration of questionnaire to the loggers and farmers in the communities in and around the reserves. this method involved asking an initial contact within a population to identify other potential participants until the required number of sample size is reached. basically, the population for this study consisted of farmers, timber contractors and forest guards. six communities were selected from each reserve. the communities chosen are iguemokhua, oben, ugo, iguere, and evuarhue and sakponba for sokponba forest reserve and for ehor bc 16/1 forest reserve, ugiehudu, eguaholor, ohe, uhi, egbisi and uhie. these communities were selected because of their proximity to the forest reserves. a total of 100 copies of questionnaire were administered for this purpose across the selected communities. the study employed the use of landsat 4, 1987 tm; landsat 7, 2002 etm+ and landsat 8, 2018 oli/ tirs images. the three images corresponded with path 189, row 055 and 056 of the wrs-2. the images were cloud-free and had good radiometric quality as reported by the data provider. the entire images are already georeferenced and with a projected coordinates system of wgs 84 utm zone 32n. the clipping of the boundaries of the forest reserves areas, was carried out using arcgis 10.1 and a colour composite of band 4, 3 and 2 was created because of its usefulness in vegetation analysis and forest monitoring. these composites were imputed into environment for visualising images (envi) software via the external landsat file format, geostationary earth orbit tagged image file format (geotiff). supervised classification method was employed by assigning pixel to classes. the knowledge obtained during reconnaissance visits to the study areas was used in the creation of training sites. maximum likelihood classifier algorithm was used in transforming the spectral signature of the training sites into various land use and land cover types present in the study area (table 1). several other post classification algorithms such as majority analysis, clump and sieve classes were used to refine the classification. change detection statistic was used to compile a detailed tabulation of changes between two classification periods; 1987-2002, 2002-2018 and 1987-2018. while the statistics report included a class for class image difference, the analysis focused primarily on the changes which have occurred in the 78 initial state classification. the analysis identified the classes into which pixels changed in the final state. several methods were adopted to identify, describe and quantify differences between images of the same scene at different times. this was useful in identifying the various classes which change from one class to another. the change statistic report table was divided into two, the initial state classes in the column and the final state classes in the row (figure 2-13). table 1: description of major land use land cover classification scheme. class description matured forest forest with merchantable trees. light forest secondary forest, shrubs and or herbaceous vegetation association agricultural land arable land, permanent crops, pastures and heterogeneous agricultural areas water rivers and streams settlements these are villages within or around the reserves figure 3. false colour composite satellite imagery of ehor forest reserve for 1987. figure 2. false colour composite of sateliteimagery of sokponba forest reserve for 1987. figure 4. false colour composite of satelite imagery of sokponba forest reserve for 2002. figure 5. false colour composite satellite imagery of ehor forest reserve for 2002. iyekekpolor and balogun/ journal of tropical forestry and environment vol. 10 no. 01 (2020) 75-86 79 figure 6. false colour composite of satelite imagery of sokponba forest reserve for 2018. figure 7. false colour composite satellite imagery of ehor forest reserve for 2018. figure 8. classified satellite imagery of sokponba forest reserve for 1987. figure 9. classified satellite imagery of ehor forest reserve for 1978. figure 10. classified satellite imagery of sokponba forest reserve for 2002. figure 11. classified satellite imagery of ehor forest reserve for 2002. 80 3. results and discussion accuracy assessments of the classified images were carried out and results (table 2) showed high level of accuracy (above 84%). overlay operation was carried out by superimposing the shapefile of the various classes of land use/ land cover of 1987, 2002 and 2018 of a particular reserve on each other. the essence of this is to enhance effective visualisation and to determine the extent to which the forest reserves have changed within the period under review. from the result obtained, it is obvious that the forest reserves were severely depleted of its resources, as shown in figures 8 to 13. table 2: confusion matrix and kappa coefficient table. type overall accuracy (%) kappa coefficient sokponba 1987 (762/839) 90.82 0.8720 sokponba 2002 (683/753) 90.70 0.8705 sokponba 2018 (178/211) 84.36 0.7642 ehor bc16/1, 1987 (395/423) 93.38 0.9003 ehor bc16/1, 2002 (477/530) 90.00 0.8499 ehor bc16/1, 2018 (459/510) 90.00 0.8503 figure 12. classified satellite imagery of sokponba forest reserve for 2018. figure 13. classified satellite imagery of ehor forest reserve for 2018. figure 14. overlay of classified imagery of sokponba forest reserve for 1987 and 2018. figure 15. overlay of classified imagery of ehor forest reserve for 1987 and 2018. (source: field work, 2019) iyekekpolor and balogun/ journal of tropical forestry and environment vol. 10 no. 01 (2020) 75-86 81 3.1 sokponba forest reserve 1987-2018 the forest reserve within the 31 years period, witnessed a drastic decreased and reduction of the forest resources as only a tiny portion 4.3% of the entire forest was left (figure 14). table 3 reveals that during this period, about 95.714% of the forest areas were converted mainly to plantation (3.8%). also, within this period, there was 12.633% expansion of settlement and bare surfaces in the areas which were hitherto forest. the forest reserve was divided into 175 compartments made up of different merchantable species of trees. these compartments were allocated to timber contractors for exploitation by the state government for a fee, which is the major reasons for the forest depletion. also, illegal lumbering, contributed to deforestation of the forest reserve, likewise farming activities carried out by the people within and outside the forest reserve area. table 3: change in sokponba forest reserve between 1987 and 2018 at final state. class initial state vegetation settlement and bare surfaces plantation and farmland water row total total unclassified 0.004 0.010 0.001 0.092 0.548 100.000 matured forest 4.286 1.613 1.541 7.077 99.977 100.000 settlement and bare surfaces 12.633 9.210 3.752 0.000 99.933 100.000 plantation and farmland 82.973 89.072 94.683 27.757 99.917 100.000 water 0.101 0.054 0.018 65.028 99.945 100.000 unclass 0.004 0.041 0.005 0.046 0.013 100.000 class total 100.000 100.000 100.000 100.000 class change 95.714 90.790 5.317 34.972 image difference -94.542 -13.416 183.203 -17.004 (source: field work, 2019) 3.2 land change process in sokponba forest reserve data from table 4 indicate that within thirty-one years, sokponba forest reserve, which was 28,913.63 ha (57.9%) in 1987, decreased to 8,641.33 ha (17.3%) in 2002. it further decreased drastically to 1,578.15 ha (3.2%) in 2018. this is alarming. while buildings and bare surface and waterbody decreased, planation and farmland continued to witness tremendous expansion, from 15,357.96 ha (30.8%) in 1987 to 36,402.66 ha (72.9%) in 2002 and further increased in size to 43,494.21 ha (87.0%) in 2018. table 4: sokponba 1987-2018, land change process. class 1987 (ha) % 2002 (ha) % 2018 (ha) % matured forest 28,913.63 57.90 8,641.33 17.30 1,578.15 3.20 plantation and farmland 15,357.96 0.80 36,402.66 72.90 43,494.21 87.00 buildings and bare surface 5,469.48 11.00 4,747.50 9.50 4,735.71 9.50 waterbody 195.84 0.39 168.66 0.34 162.54 0.33 total 49,936.91 100.00 49,960.15 100.00 49,970.61 100.00 (source: field work, 2019) 82 3.3 ehor forest reserve (area bc 16/1) 1987-2018 table 5 indicates that ehor bc 16 forest reserve between 1987 and 2018, a period of 31 years, witnessed a lot of changes in the composition, content and structure of the forest (figure 15), as only 22.219% of the total forest reserve area was left. during this period, the forest reserve experienced an alarming rapid deforestation of the forest resources and conversion, with about 73.8% of the land area converted to plantation and farmland. the loss of the forest can be attributed to the presence of merchantable economic trees in commercial quantities, the allotment of compartments to timber contractors for exploitation by the state government for a fee, illegal lumbering by individuals. table 5: change in ehor forest reserve between 1987 and 2018 at final state. class initial state matured forest plantation and farmland row total class total unclassified 0.002 0.038 0.348 100.000 matured forest 22.219 22.516 99.887 100.000 plantation and farm land 73.773 77.326 99.878 100.000 unclass 0.120 0.016 100.000 class total 100.000 100.000 class change 73.781 22.674 image difference -70.863 554.279 (source: field work, 2019) 3.4 land change process in ehor forest reserve table 6 illustrates the land change process which occurred in ehor forest reserve area. the matured forest as at 1987 was 11,128.86 ha, it reduced in size in 2002 to 10,590.39 ha, though it may be considered very minimal. the forest reserve between 2002 and 2018, witnessed a shocking and alarming depletion of its resource, as a total of 7,348.11 ha of forest land was converted. the reserve reduced to 3,242.28 ha in 2018. while the forest kept decreasing in size and resource, plantation and farm land witness increased expansion from 1,424.97 ha (11.4%) in 1987 to 1,970.64 ha (15.7%) in 2002 and to 9,323.28 ha (74.2%) in 2018. figure 16 graphically shows the changes in the two forest reserves from 1987 to 2018 in a combine graph. table 6: ehor, 1987-2018, land change process. (source: field work, 2019) the genders composition of the respondents to the questionnaire administered to the residents of communities in and around ehor and sakponba forest reserves shows that 57.0% were males, while females were 43.0%. among the respondents, 24.0% do not have formal education, 39.0% had education up to the primary school level while 21.0% of them attended secondary school, 16.0% of the class 1987 (ha) % 2002 (ha) % 2018 (ha) % matured forest 11,128.86 88.6 10,590.39 84.3 3,242.28 25.8 plantation and farmland 1,424.97 11.4 1,970.64 15.7 9,323.28 74.2 total 12,553.83 100.0 12,561.03 100.0 12,565.56 100.0 iyekekpolor and balogun/ journal of tropical forestry and environment vol. 10 no. 01 (2020) 75-86 83 respondents have tertiary education. it could be said that majority of the population is literate and could understand the questions administered to them. majority (87.0%) of the respondents are farmers while timber contractor accounts for 13.0%. this shows that farming and logging are the major activities going on in the various forest reserves. figure 16. land use land cover statistics of the reserves 1987-2018. about 28.0% of the respondents have stayed for 1-5 years, those who have stayed for 6-10 years were 12.0%, also 5.0% of them have stayed for 11-20 years and 51.0%, have stayed for 20 years and above. more than half of the respondents have stayed long enough to give informed response to the questionnaire. about 75.0% of the farmers carry out their farming operations in the reserve, 12.0% farm in free areas while 13.0% of the respondent did not indicate the location of their farm lands. among the farmers, 41.0% indicated that they got their farm land from the government, 28.0% from the communities, while 9.0% of the respondents got theirs from individuals and 2.0% of the people decided to farm in the reserves without permission from anybody. about 20.0% of the farmers did not return answer to the question on source of their farmland. farmers who make use of the reserve pay certain amount of money for the use of the land annually. about 69.0% of the respondents affirm that they pay below n 100,000 per hectare of land while 1.0% says that they pay above n 100,000 per hectare of land. about 30.0% of the respondent decline answers to this question. findings further reveals that about 31.0% of the respondents have been farming there for about 1-5 years, 33.0% for about 6-10 years while 4.0% and 6.0%, have spent 11-20 years and above 20 years respectively. this long numbers of years that farming has been taken place in the reserves account partly for the current state of the reserves. analysis shows that 3.0% of the timber contractors have been operating in the reserves for about 1-5 years, while 6.0 % have worked there for 6-10 years. information from timber contractors shows that 6.0% of loggers carry out their logging activities in the state government allotted compartment while about 3.0% illegally exploit the forest resources, 2.0% of the contractor operates in free areas and 2.0% operates both in the reserves as well as free areas. majority (87%) of loggers decline response to the question. information shows that timber contractors who are allotted compartments in the reserves pay various amount of money to the government. about 1.0% of the contractor agreed that they pay between 28,913.67 8,641.33 1,578.15 0 36,402.66 43,494.21 11,128.86 10,590.39 3,242.28 1,424.97 0 9,323.28 0 10,000 20,000 30,000 40,000 50,000 1987 2002 2018 land use land cover (ha) y e a r ehor ehor sakponba sakponba 84 n 200,000-400,000 per compartment, 5.0% pay between n 400,001-600,000 and 3.0%, pay above n 600,000. though 91% of loggers did not return answer to this question their response may not be too far from others. this study assessed sokponba and ehor forest reserves using geospatial tools and questionnaire survey to identify the extent of deforestation and the factors responsible for the deforestation. the study reveals that there has been an alarming reduction in the size, content and structure of the forest reserves areas. the sokponba forest reserve which had a total of 28,913.67 ha of forest land in 1987, had only about 1,578.15 ha left in 2018. within the 31 years period, the forest reserve loss about 27,335.52 ha to other land use types. on the other hand, plantation and farmland increased from 15,357.96 ha in 1987, to 36,402.66 ha, in 2002 and to 43,494.21 by 2018. likewise, ehor bc16/1, recorded reduction in the forest land area from 11,128.86 ha in 1987, to 3,242 ha in 2018. about 7,886.58 ha of the forest area was deforested. in the same vein, plantation and farmland increased from 1,424.97 ha, 1,970.64 ha and 9,323.28 ha, in 1987, 2002 and 2018 respectively. according to eseigbe and oni (2018), lack of comprehensive policies on environmental laws and issues, inadequate legal framework and lack of implementation of the forest act of 1999 are some of the major reasons why people still encroach forest reserves. the forest reserves which were once dense with vegetation, has been depleted of its forest resources, thereby leaving the reserve almost devoid of economic trees. the current state of the reserves with little or no forest remaining, negated the essence of its delineation as forest reserves areas. the deliberate government policies of allocating compartment to timber contractors for logging, as well as land concession to multinational firms and private individuals for oil palm plantation are the factors that were responsible for the depletion of the forest reserves. there is no deliberate attempt by the state government to plant trees in the deforested areas, instead most part of the reserves have been de-reserved to make room for farmers who pay per hectare for oil palm, rubber, cocoa, plantain and pineapple plantations. 4. conclusion as deforestation is taking place in these two reserves under study the same thing is happening in other reserves in the state. it has been observed that at the inception, forest reservation was 25% of the total land area of the state but currently it is less than 5% (kalum et al., 2010). it could be rightly said that urgent need for fund by the state government overrides the initial purpose of creating the reserve. it also indicates that the need of the presence is not taking into consideration the need of the future generation which negate the concept of sustainability. the environmental consequences of this deforestation is already manifesting in the number of gully erosion sites in the state. besides, the implications of deforestation on global warming demands that a lot of efforts and strategies has to be adopted in other to address the current trend. it is recommended that the government should stop allocating these compartments, in other to preserve the remaining patches of forest. the government should adopt taungya farming system, by planting of exotic trees in places which have been converted to farm lands and put in measures to check that these afforested areas are not deforested again. references adedeji, o.h., tope-ajayi, o.o. and abegunde, o.l., 2015. assessing and predicting changes in the status of gambari forest reserve, nigeria using remote sensing and gis techniques. journal of geographic information system, 7:301-318. aliyu, m.g., and abdullahi, l.t., 2014. assessment of environmental changes in the fufore area of adamawa state, nigeria. iosr journal of environmental science, toxicology and food technology (iosr-jestft). iyekekpolor and balogun/ journal of tropical forestry and environment vol. 10 no. 01 (2020) 75-86 85 ati, o.f., sheyin, t., abbas, i. and muhammad, s., 2010. assessing changes in kagoro forest, kaduna state nigeria using remote sensing and gis. research journal of applied sciences, engineering and technology, 2:121-132. akingbogun, a.a., kosoko, o.s.o.a. and aborisade, d.k., 2012. remote sensing and gis application for forest reserve degradation prediction and monitoring. in: first fig young surveyors conference knowing to create the future, rome, 4-5 may 2012, pp. 1-27. aweto, a.o., 1990. plantation forestry and forest conservation in nigeria. the environmentalist, 10:2734. batta, h., ashong, c.a. and bashir, a.s., 2013. press coverage of climate change issues in nigeria and implications for public participation opportunities. journal of sustainable development, 6. dewan, a.m., yamaguchi, y. and rahman, m.z., 2012. dynamics of land use/cover changes and the analysis of landscape fragmentation in dhaka metropolitan, bangladesh. geojournal, 77:315330. eseigbe, j.o. and oni, m.i., 2018. legal and regulatory reforms of forest resources conservation in edo south, edo state, nigeria. journal of law, policy and globalization, 72:38. farlex, a., 2014. forest reserve-definition of forest reserve. www.thefreedictionary.com/forest+reserve. accessed 10 june 2014. food and agriculture organization (fao), 2010. global forest resources assessment 2010: main report, fao forestry paper, 163. fearnside, p.m. and barbosa, r.i., 2004. accelerating deforestation in brazilian amazonia: towards answering open questions. environment conservation, 31:7-10. foody, g.m., 2003. remote sensing of tropical forest environments: towards the monitoring of environmental resources for sustainable development. international journal of remote sensing, 4035-4046. kalu, c. and ilavbarhe, k.o., 2010. competitive land rents: the bane of forest conservation in edo state, nigeria. research journal of forestry, 4:179-184. kumar, d., borah, s. and shankar, u., 2010. temporal forest cover change monitoring in chakrashila wildlife sanctuary, assam, india using remote sensing and gis. communicated data. mmom, p.c. and mbee, m.d., 2014. population pressure and forest resource depletion in gele gele forest reserve of edo state. nigeria international journal of physical and human geography, 2:10-21. gunlycke, n. and tuomaala, a., 2011. detecting forest degradation in marakwet district, kenya, using remote sensing and gis. in: cooperation with scc-vi agroforestry: a minor field study. lunds universitets naturgeografiska institution-seminarieuppsatser. njungbwen, e. and mbakwe, r.., 2013. a gis and remote sensing approach to assessment of deforestation in uyo, akwa ibom state nigeria. ethiopian journal of environmental studies and management, 6. oduntan, o.o., soaga, j.a.o., akinyemi, a.f. and ojo, s.o., 2013. human activities, pressure and its threats on forest reserves in yewa division of ogun state, nigeria. e3 journal of environmental research and management, 4:260-267. ojonigu, f.a., sheyin, t., abbas, i. and mohammed, s.o., 2009. assessing changes in kagoro forest, kaduna state nigeria using remote sensing and gis. research journal of applied sciences, engineering and technology, 2:121-132. okeke, o.f., 2013. land cover change analysis in the afi-mbe-okwangwo landscape, cross river state, nigeria. www.wcsnigeria.org. accessed 20 june 2015. olakunle, o.f., omotayo, a. and odewumi, s.g., 2011. pattern and problems of deforestation in southwestern nigeria. international journal of academic research, 3. 86 oyebo, m.a., 2006. history of forest management in nigeria from 19th century to date. in: salami, a.t. (ed.). in: imperatives of space technology for sustainable forest management in nigeria. proceedings of an international stakeholders workshop sponsored by national space research and development agency, abuja, pp. 1-14. reddy, c.s., sreelekshmi, s., jha, c.s. and dadhwal, v.k., 2013. national assessment of forest fragmentation in india: landscape indices as measures of the effects of fragmentation and forest cover change. ecological. engineering journal, 60:453-464. krishna, p.h., saranya, k.r.l., reddy, c.s., jha, c.s. and dadhwal, v.k., 2014. assessment and monitoring of deforestation from 1930 to 2011 in andhra pradesh, india using remote sensing and collateral data. current science, 867-875. usman, b.a., and adefolalu, l.l., 2010. an appraisal of nigerian national policy on forestry, wildlife and protected areas. environmental issues, 3:50. yohanna, p., innocent, r. and emmanuel, b., 2012. the application of remote sensing and geographic information system (gis) for monitoring deforestation in south-west nigeria. journal of environmental issues and agriculture in developing countries, 4:6-11. abeysekara et al. /journal of tropical forestry and environment vol. 8, no. 02 (2018) 13-28 13 biomass and carbon stock estimation of udawattakele forest reserve in kandy district of sri lanka a.m.s.k. abeysekara1, s.k. yatigammana2* and k.t. premakantha3 1postgraduate institute of science, university of peradeniya, peradeniya, sri lanka 2department of zoology, faculty of science, university of peradeniya, sri lanka 3forest department, sri lanka date received: 19-08-2018 date accepted: 25-10-2018 abstract carbon dioxide has gained lot of attention in recent past as a greenhouse gas, and therefore it has a potential to affect the climate pattern of the world. several anthropogenic activities are known to be responsible for the increased level of carbon in the atmosphere and disruption of the global carbon cycle. however, nature has its own mechanism of sequestering and storing the carbon in its “reservoirs”. forest has the ability to sequester carbon in their biomass and reduce the rate of increase of atmospheric carbon dioxide. the carbon sequestered in the forest trees are mostly referred to as the biomass of a tree or a forest. it has been identified five carbon pools of the terrestrial ecosystem, involving biomass. the study was designed to estimate biomass stock and then the carbon stock of the udawattakele forest reserve (7°17'58 "n, 80°38'20’’e) in kandy, sri lanka. allometric equations were used to calculate biomass of trees. the total biomass stock was estimated to be 9475.56 t ha-1 (mega gram-mg) and the total carbon stock was estimated to be 4,453.55 t ha-1 (mg) in the udawattakele forest reserve (ufr). this amount is equivalent to 16,344.52 mg of carbon dioxide in the atmosphere. ufr holds a moderate amount of biomass/carbon stock and the total carbon density of natural forest and plantations was found to be 36.55 mg ha-1 and 44.89 mg ha-1 respectively. keywords: climate change, tree diameter, allometric equation, biomass 1. introduction the assessment of carbon in the forest areas is a subject of global concern, since carbon stock is an important criterion of sustainable forest management (sfm) and in addition, it is required for greenhouse gas inventories needed in the land use, land use change and forestry (lulucf) sector, for the united nations framework convention on climate change (unfccc) reporting. plant biomass, including aboveground and belowground biomass is the main channel for co2 removal from the atmosphere.there are two key policy-related reasons for measuring carbon in forests. commitments under the united nations framework convention on climate change (unfccc), signed by more than 150 countries, require that all parties to the convention commit themselves to develop, periodically update, publish, and make available to the conference of parties (cop), their national inventories of emissions by sources, and removals by sinks of all ghgs. potential implementation of the reducing emission from deforestations and degradation (redd) as it is aiming to create financial benefits to countries whom an age their forests in a sustainable manner, while increasing the absorption of greenhouse gasses which will ultimately result in reduction of global warming greenhouse gases, including co2 play an important role on earth’s climate (kiehl and trenberth, 1997). *correspondence: sudharma_y@yahoo.com issn 2235-9370 print/issn 2235-9362 online © university of sri jayewardenepura 14 the climate change occurring throughout the globe is a serious issue that affects both biotic and abiotic systems of the planet earth. (climate change 2001, three most powerful long lived greenhouse gases in the atmosphere are carbon dioxide (co2), methane (ch4), and nitrous oxide. therefore these can be considered as primary agents of global warming (kiehl and trenberth, 1997). atmospheric co2 is utilised by the plants during the process of photosynthesis and stored as plant biomass and carbon fixation through forestry is a function of biomass accumulation and storage. carbon sequestration can be achieved by establishment of new forests and by improving the growth rates of existing forests (ranasinghe, 2010). carbon (c) is one of the most abundant elements on earth and it is a naturally occurring component of the earth’s atmosphere. atmospheric carbon is found in the form of chemical compounds, carbon dioxide (co2) and methane (ch4), which are two key greenhouse gases that occur naturally in the atmosphere. through the process of photosynthesis, forests absorb co2 from the atmosphere and storing the biomass of trees. according to the ipcc, there are five carbon pools of terrestrial ecosystem involving biomass: (a) above ground biomass, (b) below ground biomass, (c) dead mass of litter, (d) woody debris and (e) soil organic matter. the aboveground biomass of a tree constitutes the major portion of the carbon pool. it is the most important and visible carbon pool of the terrestrial forest ecosystem. the below ground biomass, which constitutes all the live roots, also plays an important role in the carbon cycle by transferring and storing carbon in the soil. a variety of methods have been developed to estimate biomass in forests and in other vegetation types. these methods differ in procedure, complexity and time requirement depending on the specific aim of the estimation operation (gunawardena, 2014). the most common approach to estimate the aboveground biomass is to establish an equation for the particular location that relates the biomass with tree variables such as dbh (diameter of brest height) and height. this is done by measuring representative samples of trees belonging to a particular population. these equations are then used to estimate the biomass that is applicable to the population from where the sample is taken (saint-andre et al., 2004). the most widely used method for estimating biomass of forest is through allometric equations. the allometric equations are developed and applied to forest inventory data to assess the biomass and carbon stocks of forests. our study aim is to estimate the carbon stock in udawattakele forest reserve which will help establishing a reference level of carbon stock. the information will later useful to compare the increase or decrease (emission or removal) the carbon stock of udawattakele especially due to human intervention. 2. materials and methodology 2.1 description of the study site udawatthakele forest reserve (ufr) (figure 1) is situated within the city limits of kandy, in the central province of sri lanka (7°17'58"n, 80°38'20"e and 635 m above mean sea level). the total area of the forest is ~113 ha (forest department, 2013). annual mean rainfall is more than 2,000 mm and the annual mean temperature is around 20o c. this was declared a forest reserve in 1897.10.15 under the gazette number 35/04. the vegetation of ufr is comprised of dense forest, abundant forest plantations of swietenia macrophylla, myroxylon balsamum, alstonia macrophylla, mesua ferrea and sapu michelia champaca, (nyanatusita and dissanayake 2013). https://en.wikipedia.org/wiki/swietenia_macrophylla https://en.wikipedia.org/w/index.php?title=myroxylon_balsamum&action=edit&redlink=1 https://en.wikipedia.org/wiki/mesua_ferrea https://en.wikipedia.org/wiki/michelia_champaca abeysekara et al. /journal of tropical forestry and environment vol. 8, no. 02 (2018) 13-28 15 figure 1: the map of udawatthakele forest reserve (study site). 2.2 biomass/carbon measurement methods a variety of methods have been developed to estimate biomass in forests and in other vegetation types. these methods differ in procedure, complexity and time requirement depending on the specific aim of the estimation operation (gunawardena, 2014). energy balance of a system is nowadays used by many researchers to estimate biomass content. single representative value of carbon content for broad forest categories are applied in the biomass average method (gibbs et al., 2007). another widely used method is conversion of measured volume estimates to biomass density using appropriate tools (brown and lugo, 1992). destructive or nondestructive method use to estimate the biomass, destructive method use to full tree harvest, cutting and weighing, or cutting, drying and weighing of the whole tree or its parts, is a simple procedure to estimate fresh and dry biomass. this method is time consuming, costly and above all destructive (vann et al., 1998). in non-destructive method trees are not felled for taking measurements (stewart et al, 1992; montas et al., 2000). this is mainly applied when the trees of interest are rare, protected or not possible to destructively sample to construct allometric relationships (brown, 1997, stewart et al, 1992, montas et al., 2000) non-destructive method takes the measurement without felling trees. so that measurements are done by climbing trees. successive measurement on stem and branches are taken along with limited sampling of branches. then the volumes are computed using the measurements taken. finally, tree densities already available are used to convert measured volumes into biomass estimates. 2.3 allometric equations for biomass estimation allometric equations need to be used when destructive estimations are not done. biomass equation relates growth parameters such as dbh, height and crown parameters to biomass. the most important variable used in these models is (dbh) (yen et al, 2010). biomass equation developed by brown (1997) was used to estimate biomass of live trees as it was a general equation developed for the areas receiving 16 1,500-4,000 mm of average annual rainfall. allometric equations developed for the estimation of above ground biomass and carbon in tropical evergreen forests shown in table 1. table 1: allometric equations developed for the estimation of above ground biomass and carbon in tropical evergreen forests. (source: gunawardena, 2014) y, tagb, agb=above-ground tree biomass [kg] q=wood specific gravity [g cm-³], d, dbh=tree diameter at breast height [cm], h=tree height [m], c_agb=above ground carbon c, bgb=below ground carbon, bgb=below ground biomass. 2.4 sampling design the study site (ufr) was divided into homogeneous strata, based on the image characteristics of the image in the google earth software which represent the study area. accordingly two strata were identified. homogenous areas was delineated using the image characteristics of google satellite image of the study area. 2.5 sample plots cluster sampling technique was used to prepare sample plots for data collection. a total of 12 plots were selected randomly to represent all the vegetation types of ufr. one plot was consisted with series of three circular sub plots in a single array. these plots have been selected using a map prepared from google image. each plot consisted of three circular sub plots. each circular subplot was 20 m in diameter, and each located 10m apart from each other (figure 2). the size and shape of the plot is a tradeoff between accuracy, precision, time, and cost for measurement (pearson et al., 2005). sample plots containing smaller subunits of various shapes and sizes are cost effective depending on the variables to be no equation author 1 tagb =exp(-2.134+2.53*ln(dbh)) (brown, 1997) 2 tagb =r*exp(-1.499+2.148*ln (dbh)+0.207 * (ln(dbh))2-0.0281*(ln(dbh))3) (chave et al., 2005) 3 tagb = rravg (dbh)2+c c=0.397, r= 0.604g/cm3 , r=0.11 (ketterings, 2001) 4 y= exp(-1.996+2.32*ln(dbh)) (brown, 1997) 5 y= exp(-2.134+2.53*ln(dbh)) (brown, 1997) 6 y= 10^(-0.535+log10((p*r 2)) p=3.1415927, r=radius (brown, 1997) 7 btot= 21.297022-6.952649*(dbh)+0.7403*(dbh) 2 (brown & iverson, 1992) 8 btot= 13.2579-4.8945(dbh)+0.6713(dbh) 2 (brown, 1989) 9 y= exp(-2.23927+2.49596*ln(dbh)) (bao huy et al., 2012) 10 ln(tagb)= c+aln (dbh) a=2.196 c= -1.201 (basuki et al.,2009) 11 y = ln(tagb)= c+aln (dbh)+bln(h) a=1.981 b= 0.541,c=-1.935 (basuki et al., 2009) 12 c_agb_kg= exp (-2.97775+2.49711*ln(dbh_cm)) (bao huy et al., 2012) 13 bgb_kg=exp(-3.73686+2.32102*ln (dbh_cm)) (bao huy et al., 2012) 14 c_bgb_kg = exp (-4.91842+2.41957*ln (dbh_cm)) (bao huy et al., 2012) 15 agb = 0.0509 x q d2 h (basuki et al., 2009) 16 bgb_kg = exp -3.73686+2.32102 ln (d) (brown et al., 2004) abeysekara et al. /journal of tropical forestry and environment vol. 8, no. 02 (2018) 13-28 17 measured. for example, for afforestation, all trees are measured in the entire sample plot, whereas data on non-tree vegetation, litter, and soil are collected in a smaller sub-plot. the forest inventory and analysis (fia) standard plot consists of a cluster of four subplots, each containing smaller nested plots for sampling understory vegetation and soils, of relatively small radius. (pearson et al., 2005). nested plots are a practical design for sampling for discrete size classes of stems. they are well suited to stands with a wide range of tree diameters or stands with changing diameters and stem densities. in this study nested plot consisting with 3 m, 4 m, and 10 m subplots were used. (figure 3) figure 2. cluster sampling design 45 a b c d 135 225 315 figure 3. sample plot design. 2.6 calculation of carbon stock the most widely used method for estimating biomass of forest is through allometric equations. the allometric equations are developed and applied to forest inventory data to assess the biomass and carbon stocks of forests. the allometric equations for biomass estimation are developed by establishing a relationship between the various physical parameters of the trees such as the diameter at breast height, height of the tree trunk, total height of the tree, crown diameter, tree species, etc. methodology used in this study considered the guidelines laid in the ‘good practice guidance for land use, land use change and forestry’ by ipcc (2003) and the methodology suggested by pearson et al., (2005) was also used in this method to estimate the carbon stock in trees outside forests systems of nuwara eliya district in sri lanka. a, r=10 b, r=4 c, r=3 d, r=2 e=30 cmx30 cm micro plot(r=radius) 18 2.7 estimation of above ground biomass (abg) live trees the equation developed by brown (1997) was used in the study. (1) (2) palm trees (3) (4) liana (5) (6) dead trees there may be different types of dead trees in a forest. they are, recently dead trees which retain small branches and twigs, resembling a live tree except for the absence of leaves. the other one is old dead trees which have only the conical shape of the main stem as branches have been fallen over the years. in this study only the recently dead trees were found. therefore the same equation that was used to calculate biomass of trees was used here, however, subtracting 5 percent for the fallen leaves. (7) saplings (8) (9) seedlings twenty to 30 seedlings were cut at the ground level and weighed. a sub sample from each seedling was taken and weighed. samples were oven dried at 105º c to a constant mass. then the ratio between wet and dry mass of the sub sample was used to get the dry mass of entire seedlings. finally, mean biomass of seedlings was calculated by averaging the estimated value of all the seedlings. these values were used to scale up counts of seedlings in the system (pearson et al., 2007). (10) (11) litter (12) woody debris (dead wood) abeysekara et al. /journal of tropical forestry and environment vol. 8, no. 02 (2018) 13-28 19 (13) (14) (15) where; x= abg biomass (kg) dbh = diameter at breast height (cm) x1 = abg biomass (kg/ha) a = area of the plot h = height (m) 10, 000 = constant n = number of live seedlings 0.001= constant y = average weight of a seedling (g) r = dry weight/fresh weight a1=diameter of small end of dead wood (cm) a2 = diameter of large end of dead wood (cm) l = length of the stump (m) v=volume 2.8 estimation of below ground biomass the most efficient way to estimate below ground biomass is to apply the widely accepted general model of pearon et al., (2009). in estimating belowground biomass, an equation is applied to total above ground biomass as a whole and not to individual tree biomass (except litter and downed wood). bbd=exp (-1.0587+0.8836 xln (abd)) (16) where; abd = above ground biomass density (mg/ha) bbd = below ground biomass density (mg/ha) mega gram (mg) is the international reporting unit of above ground biomass which is equal to tons/hectare (t/ha). 2.9 total biomass total biomass density was calculated by summing up mean carbon density of each component of carbon pool. (17) where; btag =above ground biomass of live trees btbg =below ground biomass of live trees bdtag =above ground biomass of dead trees bdtbg=below ground biomass of dead trees bspag=above ground biomass of saplings bspbg=below ground biomass of saplings bsdag=above ground biomass of seedlings 20 bsdbg=below ground biomass of seedlings bwdb=biomass of wood debris bl=biomass of litter 2.10 total carbon density in this study total biomass was converted to total carbon by multiplying by 0.47. (premakantha et al., 2014) (18) 2.11 total carbon stock (mg) total carbon stock of ufr was calculated by multiplying average carbon density of all the car bon pool by the area of ufr using the method suggested by kauffman and donato (2012). (19) tc-e = total carbon dioxide equivalents (mg) total carbon stock was multiplied by 3.67 to obtain the co2 equivalents (mg) as the ratio of molecular weights between carbon dioxide and carbon is 3.67 (kauffman and donato, 2012). 3. results and discussion total carbon density of natural forest and plantations was found to be 36.55 mg ha-1 and 45.06 mg ha-1 respectively. this result is too low when compared to the study by costa and suranga (2012). according to the results, live trees provided the major contribution for carbon sequestration in ufr and 16,344.5 mg carbon equivalents are stored. this value can be used as a reference level for future studies. 3.1 tree density in ufr table 3 shows the tree density of two vegetation types in ufr. tree densities of natural forests and plantations were found to be 1,757 individuals per hectare and 1,006 individuals per hectare, respectively. table 3: the abundant species and their densities in the two vegetation types (note: some plantation species can be observed in high density in natural vegetation due to closeness of the two vegetation natural forests forest plantations species tree density (individuals /ha) species tree density (individuals /ha) mesua ferrea 223 sweetinia macrophylla 234 crayota urens 127 myroxylon balsamum 127 sweetinia macrophylla 121 mesua ferrea 127 symplocos cochinchinensis 104 alstonia macrophylla 110 myroxylon balsamum 93 pongamia pinnata 64 theobroma cocao 64 filicium decipiens 53 micromelum minutum 64 artocapus nobilis 52 artocapus nobilis 61 phyllanthus indicus 48 acronychia pedunculata 61 neolitsea cassia 32 abeysekara et al. /journal of tropical forestry and environment vol. 8, no. 02 (2018) 13-28 21 tree densities and species composition of two vegetation types are important because they directly affect biomass estimations. sweetinia macrophylla, myroxylon balsamum, alstonia macrophylla, mesua ferrea, crayotaurens, theobroma cocao, micromelum minutum, artocapus nobilis, acronychia pedunculata are the most abundant species found in both vegetation types. of each species, there are more than 50 individuals per hectare. the amount of biomass and the carbon stock differs between species, both in the case of trees and shrubs (elias and potvin 2003; lamlom and savidge 2003), as well as herbs and mosses (tutersky, 2003). species composition and community structure had significant impacts on biomass carbon density. results show that the tree density in the ufr falls far below, compared to other natural forests. therefore, there is a possibility of inclusion of more trees into both vegetation types and thereby increasing the carbon/biomass stock in the ufr. on the other hand, it was observed that number of seedlings is inadequate in terms of regeneration. 3.2 frequency distribution of tree diameter classes frequency distribution of tree diameter classes in natural forests in ufr shows a reverse j shape curve similar to that of other natural forests. the curve illustrates that 42% of the trees are in between 1019 cm. figure 4 and diameter class distribution of plantations also shows a reverse j shape curve unlike other plantations, (figure 5) due to the presence of non-plantation species. figure 4. diameter class distributions of natural forests. frequency distribution of tree diameter classes for both vegetation types showed a reverse j shape curve. diameter distribution of trees in both vegetation types showed that the percentage of number of trees in smaller diameter classes is more than the larger diameter classes. the amount of biomass contained in different tree diameter classes showed opposite pattern to that of tree diameter class distribution. therefore, mature trees contain large amount of biomass in natural vegetation of the ufr. plantations also showed the same pattern of increasing biomass density with the increase of size of diplodiscus verrucosus 48 calophyllun spp. 32 cryptocaryamembranacea 48 berrya cordifolia 32 filicium decipiens 48 gmelina arborea 32 alstonia macrophylla 47 terminalia belarica 32 semecarpus coriacea 42 nothopegia beddomei 32 0 20 40 60 80 100 120 n o o f tr e e s dbh cl ass 22 diameter class. (figure 4 and figure 5) the ratio of carbon stock/growing stock decreases with tree size, indicating that the contribution of stem biomass becomes increasingly large as trees grow in size (lehtonen et al., 2004; kauppi et al., 2006). figure 5. diameter class distributions of forest plantation. large trees have significant benefits, for example, they can constitute a large proportion of the carbon stock and affect greatly the carbon density of forests. large trees usually have deeper roots and long lifetimes. they affect forest structure and function and provide habitats for other species. land management has been a key driver in the change in the stocks of large trees. it is also observed that at times the trees are in clusters hindering the potential growth of them due to competition among them. thus, it is proposed to carry out field based inventories and to perform scientific studies prior to implementing silvicultural programmes in the plantations and make decisions in thinning and inclusion of more trees. 3.3 biomass content in different diameter classes figure 6 illustrates the biomass density by different diameter classes in the natural forests of ufr. the lowest biomass density is shown in the 10-19 cm diameter class. it also shows that biomass density increases with the size of diameter class. therefore, that larger diameter classes contain higher amount of biomass. figure 7 illustrates the biomass density by different diameter classes in plantations. similar to natural vegetation of ufr, 10-19 cm diameter class holds the least biomass density. plantations too show the pattern of increasing biomass density with the increase of size of the diameter class. figures 8 and 9 show the contribution of each component to the total density of natural forests indicating that biomass partitioning of two vegetation types differ greatly. however, trees are the major contributor to biomass in both vegetation types. 0 10 20 30 40 50 60 70 80 90 n o o f tr e e s dbh class abeysekara et al. /journal of tropical forestry and environment vol. 8, no. 02 (2018) 13-28 23 figure 6: biomass densities in different diameter classes of trees of natural forests. figure 7: biomass densities in different diameter classes of trees of forests plantation. biomass partitioning among components showed the contribut ions of different components towards the total biomass contents. therefore it is apparent that the trees are the largest contributor to biomass production similar to other natural forests (lago, 1992). however, very low contribution for carbon by seedlings and herbaceous vegetation in the ufr similar to other tropical forest (yanqiu et al., 2015). 24 figure 8: biomass partitioning among different components of natural forests in the ufr. figure 9: biomass partitioning among different components of forest plantation in the ufr. similar to the results of this study, results of the estimation of carbon stock in tankawati natural hill forest of bangladesh revealed that the total carbon stock of the forest was 283.80 mg ha-1 whereas trees produce 110.94 mg ha-1, undergrowth (shrubs, herbs and grass) 0.50 mg ha-1, litter fall 4.21 mg ha-1 and soil 168.15 mg ha-1 (up to 1 m depth). lugo (1992) mentioned that the amount of biomass in undergrowth shrubs, vines, and herbaceous plants can be variable but it is generally about 3% or less of the total biomass of more mature forests. 3.4 total biomass stock in the ufr. table 4: total biomass stock of ufr component natural forests (mg) plantations (mg) trees 3,923.84 2013.00 liana 0 596.15 seedlings 0.14 0.034 saplings 7.26 5.37 dead wood dead trees 2,077.72 646.12 down wood 0.049 0.042 litter 83.55 41.61 71.234 46.601 1.874 0.110 0.0020.000 trees dead wood (downed wood+ dead trees) litter saplings 64.2717.88 24.35 1.53 0.140 0.001 trees liana dead wood (downed wood+ dead trees) litter saplings abeysekara et al. /journal of tropical forestry and environment vol. 8, no. 02 (2018) 13-28 25 table 4 gives the total biomass stock in each component of both natural forests and plantations. total biomass stock of the ufr is 9,475.56 mg. out of that, 64.3% of biomass is from natural forest and the rest is from the plantations. total biomass mainly consists of two components, namely the live tree component and dead wood component. contribution for total tree biomass from natural forests and plantations was 65.33% and 34.67% respectively. out of 2847.98 mg of deadwood biomass stock, 75.89% was from natural forests while 24.11% was from plantations. clear vertical stratification of the forest canopy layer could not be identified in the field work stage where measurements were taken from trees and other components. it indicates that vegetation has dissimilar structure to that of other natural forests. due to this non storied nature in the canopy, light penetration to lower levels may be less, hindering the growth of plants in lower layers contributing to poor biomass accumulation from them. 3.5 total carbon stock in the ufr total carbon stock is a function of the area and the carbon density, and hence the total biomass stock was more in natural forests compared to plantations as the natural forests extent is higher (table 5). table 5: carbon stock of ufr carbon stock of the ufr was fairly low compared to the aboveground carbon stock of natural forests in different asian countries. for example, thailand (98.76 mg ha-1), malaysia (100 mg ha-1) and philippines (86 mg ha-1) (pibumrung et al., 2008). in sri lanka costa and suranga (2012) estimated an above and belowground carbon density at 157 mg ha-1 of monoculture and mixed plantation forests in nuwara eliya district in 2008. mattson’s carbon estimate of six forest types in sri lanka has given an average value of 120 to 130 mg ha-1. when compared to those carbon densities in both systems, carbon densities of plantation and natural forest in ufr were significantly low. this can be due to several factors, such as illegal felling, inappropriate management, impact of climate change, destruction of under growth because of over visitation to the park. 3.6 total carbon dioxide equivalent stock in the ufr. table 6: amount of carbon dioxide stored in ufr vegetation type carbon stock (mg) co2-e (mg) natural forest 2,863.49 10,508.99 plantation 1590.06 5835.53 table 6 shows the amount of carbon dioxide equivalent stored in ufr. both vegetation types in the ufr had stored a total of 16,321.77 mg carbon equivalents at the time of study. however there is no universally accepted methodology in estimating biomass/carbon stock either in forests or in other vegetation. however various methods are available but none is technically precise and accepted by all the scientists. estimation of total organic carbon requires a complete enumeration of the entire ecosystem vegetation type extent (ha) total carbon density (ma/ha) carbon stock (mg) natural forest 78.35 36.55 2,863.47 plantation 35.28 45.06 1590.06 26 components is difficult lengthy, tedious and expensive. because of that, only a very small number of studies have been done based only on samples, even so they may not be comparable as the methodology and the materials used are different. 4. conclusion it is clear that ufr holds a moderate amount of biomass/carbon stock and it contributes to mitigate climate change which is a prime global issue at present. either keeping the forest reserve as it is or by increasing biomass/carbon stock through changing species composition and the structure, is the major challenge ahead of us. in line with this, assessing biomass/carbon stock is a pre-requisite. it can be concluded that this methodology used in this study can be successfully applied for assessment of biomass/carbon stock in the natural forests and plantations in the kandy district sri lanka. references abdallah, f., chaieb, m. (2012).the influence of trees on nutrients, water, light availability and understorey vegetation in an arid environment. applied vegetation science, 15:501–512. adikari, m. (2005). a non-destructive approach for quantitative assessment of tree resources outside forest, unpublished msc thesis. international institute for geo-information science and earth observation (itc), enschede, the netherlands. america's climate choices panel on advancing the science of climate change, national research council (2010). advancing the science of climate change. the national academies press, washington, d.c. basnayake, b.r.s.b. (2007). climate change, present and future perspective of sri lanka, climate change in sri lanka. impact, adaptation and mitigation, proceedings of the national conference on climate change, sri lanka. bao, h.u.y., anh, p.t., hung, v., houng, n.t.t. (2012). report on estimation of co2 sequestrated in evergreen broad leaf forest in central highland of vietnam for reducing deforestation and forest degradation program. tay nguyen university, dak lac, vietnam. basuki, t.m., van leeke, p.e., skidmore, a.k., hussin, y.a. (2009). allometric equation for estimating the above ground biomass in tropical lowland dipterocarpus forest. brown, s., lugo, a.e. (1992). above ground biomass estimates for tropical moist forests of the brazilian amazon. interciencia, 7, 8-18. brown, s., iverson, l.r. (1992). biomass estimate for tropical forest. world resource review, 4, 366 384. brown, s. (1997). estimating biomass and biomass change of tropical forests, a primer. a forest resources assessment publication, fao forestry paper 134. food and agriculture organization of the united nations, rome. brown, s. (2002). measuring carbon in forests, current status and future challenges. chandrapala, l. (1997). comparison of areal precipitation of sri lanka on district basis during the period 193160 and 196190. in proceedings of the national symposium on climate change, march 1997, colombo, sri lanka. chave, j., andalo, c., brown, s., cairns, m.a., chambers, j.q. (2005). tree allometry and improved estimation of carbon stocks and balance in tropical forests. oecologia, 145: 87 99. climate change (2001), third assessment report in ipcc de costa, w.a.j.m., suranga, h.r. (2011). estimation of carbon stocks in the forest plantations of sri lanka. department of crop science, faculty of agriculture, university of peradeniya, peradeniya. elias, m., potvin, c. (2003). assessing interand intra-specific variation in trunk carbon concentration for 32 neotropical tree species. canadian journal of forest research, 33, 1039−1045. field guide for forest biomass and carbon estimation (2011). woods hole research center de gier, a. (2003). a new approach to woody biomass assessment in woodlands and shrub lands. in p. roy (ed), geoinformatics for tropical ecosystems, india, 161-198. http://www.nap.edu/catalog.php?record_id=12782 abeysekara et al. /journal of tropical forestry and environment vol. 8, no. 02 (2018) 13-28 27 gibbs, k.h., brown. s., niles. o.j., foley. a.j. (2007). monitoring and estimating tropical forest carbon stocks: making redd a reality. environment research letter2 (october –december). gillon, j. (2001). the lowdown on carbon s inks. retrieved on 5.24.2007. green, michael j.b. (1990). iucn directory of south asian protected areas. iucn. pp. 263-265. isbn 978-2-8317-0030-4. gunawardena, a.r. (2014). land use, land cover types in sri lanka using remote sensing as nondestructive sampling technique. phd thesis, post graduate institute of agriculture, university of peradeniya, peradeniya, sri lanka. hezri, a.a., hasan, m.h. (2006). towards sustainable development. the evolution of environmental policy in malaysia. natural resource forum 30(1): 37-50. karunaratna, n. (1986). udawattalale, the forbidden forest of the kings of kandy, colombo department of national archives. pp. 141148. kauffman, j.b., donato, d.c. (2012). protocols for the measurement, monitoring and reporting of structure, biomass and carbon stocks in mangrove forests. working paper 86. kauppi, p.e., ausubel, j. h., fang, j., mather, a. s., sedjo, r. a., and waggoner, p. e. (2006). returning forests analyzed with the forest identity, p. national acadademy of science usa, 103, 1757417579. ketterings, q.m., coe, r., van noordwij, k.m., ambagau, y., palm, c.a. (2001). reducing uncertainty in the use of allometric biomass equation for predicting above ground tree biomass mix secondry forest. forest ecology and management, 146, 199 209. kiehl, j.t., trenberth, k.e. (1997). earth’s annual global mean energy budget. bulletin of the american meteorological society, 78(2), 197-208. lamlom s.h., savidge r.a. (2003). a reassessment of carbon content in wood variation within and between 41 north american species. biomass bioenergy 25, 381–388. lugo a.e. (1992). comparison of tropical tree plantations with secondary forests of similar age. ecological monographs, 62, 141. national climate change adaptation strategy for sri lanka, 2011 to 2016. (2010) ministry of environment, sri lanka. montes, n., gauquelin, t., badri, w., bertaudiere, v., zaoui, e.h. (2000). a nondestructive method for estimating above-ground forest biomass in threatened woodlands. forest ecology and management, 130(1-3), 37-46 namayanga, l.n. (2002). estimating terrestrial carbon sequestered in aboveground woody biomass from remotely sensed data. the use of sebal and casa algorithms in a semi-arid area of serowebotswana, itc, the netherlands. nyanatusita, b. dissanayake r. (2014) “udawattakele” a sanctuary destroyed from within, loris, journal of the wildlife and nature protection society of sri lanka, vol. 26. pearson, t.r.h., walker, s and brown, s. (2005). source book for land use, land use change and forestry projects. winrock international and the bio carbon fund of the world bank. 57. pearson, r.h., brown, s., richard a.b. (2007). measurement guidelines for the sequestration of forest carbon timothy, p 22. performance report (2013), forest department ministry of environment & renewable energy, sri lanka. pibumrung, p., gajaseni, n., popan, a. (2008). profiles of carbon stocks in forest, reforestation and agricultural land, northern thailand. journal of forestry research, 1: 11–18. premakantha, k.t., pushpakumara, d.k.n.g., sivanantherverl, t., dayawansa, n.d.k. (2014). estimation of carbon stock in trees outside forests (trof) systems of nuwara eliya district in sri lanka. punyawardena, b.v.r. (2007). agro-ecology. national atlas of sri lanka, second edition, survey department of sri lanka, sri lanka. 98-100. http://www.archive.org/details/iucndirectoryofs90gree https://en.wikipedia.org/wiki/international_standard_book_number https://en.wikipedia.org/wiki/special:booksources/978-2-8317-0030-4 28 ranasinghe, d.m.h.s.k. (2010). climate change mitigation – sri lanka’s perspective proceedings of the 15th international forestry and environment symposium, 26-27 november 2010, colombo, sri lanka razali, w.w.m, shahwahid, m.h.o. (2011). transitions to sustainable forest management and rehabilitation in malaysia. saint-andre, l., bou, a.t.m., mabiala, a., mauvondy, w., jourdan, c., roupard, o., deleporte p., hamel o., nouvellon, y. (2004). age-related equations for aboveand below-ground biomass of a eucalyptus hybrid in congo. singh, m. j. d. (2001). forest structure and biomass in a mixed forest-oil palm landscape in borneo. univ oxford, oxford. master diss abstr, 2-213. sri lanka redd+ readiness preparation proposal un-redd programme (2009). stewart, j.l., dunsdon, a.j., hellin, j.j., hughes, c. e. (1992). wood biomass estimation of central american dry zone species. tropical forestry papers, pp. 1-a-1 i-33. oxford forestry institute, university of oxford, oxford forestry institute, department of plant sciences, oxford. vann, d.r., palmiotto p. a., richard s, g. (1998). allometric equations for two south american conifers test of a non-destructive method. forest ecology and management, 106(2-3), pp. 55-71. watson, r.t., noble, i.r., bolin, b., ravindranath, n.h., verardo, d.j., dokken, d.j. (2000). land use, land-use change, and forestry. special report of the ipcc, cambridge university press, cambridge, uk, pp. 23–51. wedathanthri, h.p. hitinayake, h.m.g.s.b. (2009). invasive behavior of myroxylon balsamum at ufr. university of sri jayewardenepura. retrieved 2009-07-07. http://ybiol.tripod.com/forest/99sympo/9914weda.htm https://en.wikipedia.org/wiki/university_of_sri_jayewardenepura 2.1 description of the study site cluster sampling technique was used to prepare sample plots for data collection. a total of 12 plots were selected randomly to represent all the vegetation types of ufr. one plot was consisted with series of three circular sub plots in a single array.... nested plots are a practical design for sampling for discrete size classes of stems. they are well suited to stands with a wide range of tree diameters or stands with changing diameters and stem densities. in this study nested plot consisting with 3 m... figure 2. cluster sampling design figure 3. sample plot design. the most widely used method for estimating biomass of forest is through allometric equations. the allometric equations are developed and applied to forest inventory data to assess the biomass and carbon stocks of forests. the allometric equations for ... 2.7 estimation of above ground biomass (abg) figure 5. diameter class distributions of forest plantation. america's climate choices panel on advancing the science of climate change, national research council (2010). advancing the science of climate change. the national academies press, washington, d.c. de costa, w.a.j.m., suranga, h.r. (2011). estimation of carbon stocks in the forest plantations of sri lanka. department of crop science, faculty of agriculture, university of peradeniya, peradeniya. introduction arunkumar and joshi /journal of tropical forestry and environment vol. 4. no 02 (2014) 1-10 1 feature article pterocarpus santalinus (red sanders) an endemic, endangered tree of india: current status, improvement and the future a.n. arunkumar * and g. joshi tree improvement and genetics division, institute of wood science and technology, bangalore, india abstract pterocarpus santalinus (family – fabaceae) popularly known as red sanders is an endemic species confined to southern parts of eastern ghats of india specially in andhra pradesh. heartwood of red sanders has high demand in domestic as well as international market and the wavy grained wood is valued. along with its extensive use in furniture, the red dye obtained from the wood is used as colouring agent for textile, medicine and food. the heartwood can accumulate various elements and rare earth elements like strontium cadmium, zinc, copper and uranium. the wood has different uses in traditional and folklore medicines and is used for the treatment of diabetes, prickly heat, skin diseases and for various other ailments. a number of studies have been carried out to anatomically and phenotypicaly screen wavy grain at seedling stage. morphological variability and genetic diversity studies reveal that red sanders harbours enormous variability. though, macro and micro propagation protocol have been developed, further refinement is required for mass propagation. andhra pradesh forest department has also initiated different activities under tree improvement programme. considering the wood demand, restricted distribution, slow regeneration, illegal harvest, trade and habitat destruction, the species has been categorized as endangered by international union for conservation of nature and has been listed in convention on international trade in endangered species of wild fauna and flora and is also classified as a “reserved tree” under the andhra pradesh preservation of private forest rules, 1978. to revive the past glory of this valuable species, government agencies, farmers, entrepreneurs and policy makers have to join hands for its protection, sustainable utilization and conservation. key words: pterocarpus santalinus, conservation, red sanders, tree improvement 1. introduction pterocarpus is a well recognised genus of trees and woody climbers distributed through out the world in three tropical regions, i.e., neotropics, tropical africa and indomalaya (indian subcontinent and malay peninsula/archipelago). it consists of 35 to 40 species (klitgaard and lavin, 2005) but is estimated up to 60 species (chauhan and vijendra rao, 2003). pterocarpus has gained popularity globally for its ethnomedicinal uses and valuable bioactive compounds and the importance of this genus can be appreciated by the study carried out by saslis-lagoudakis et al. (2011) to enable the application of community phylogenies in bioscreening, and also shedding light on the processes of shaping cross cultural ethnomedicinal patterns. there are only four species found in india, pterocarpus * correspondence: arun@icfre.org tel: +91 8022190156 issn 2235-9370 print/issn 2235-9362 online © university of sri jayewardenepura 2 dalbergioides, p. indicus, p. marsupium and p. santalinus. out of these four species, international union for conservation of nature (iucn) has listed p. indicus and p. marsupium as vulnerable and p. santalinus as endangered. p. dalbergioides, an endemic species of andamans, has not been classified by iucn due to data deficiency (iucn, 2014). considering the present status lakshminarasimhan and mondal (2012) indicated that p. santalinus is critically endangered. similarly, prasad et al. (2008), suggested that it is appropriate to consider p. dalbergioides as threatened and if not protected well, may swiftly move to the next category of extinction. in the natural habitats of sri lanka, the species of pterocarpus is considered to be rare due to continuous human pressure in harvesting the trees indiscriminately (arunakumar et al., 2011). among the four species mentioned above, the most important species which needs immediate attention and concern is pterocarpus santalinus (family: fabaceae) an endemic species restricted to southern parts of eastern ghats of india. being a commercially important tree of indian forests, it is popularly known as red sanders, red sandalwood, almug and saunderswood. red sanders is a typical leguminous species of tropical dry deciduous forests of andhra pradesh being localized and predominantly confined to cuddapah landscape between 13 0 30 / and 15 0 00 / north latitude and between 78° 45´ and 79° 39´ east longitude (raju et al., 1999). it is distributed in an area of approximately 5160km 2 in its geographical spread of scattered forests and in elevated parts of chittoor, cuddapah and nellore districts of seshachalam hill ranges (150 to 900 m). it is also found partly distributed in the arcot and chengalpattu districts of tamil nadu and also in karnataka (goi, 2014). it is reported that p. santalinus occurs in other countries like china, pakistan, sri lanka and taiwan, but must have been an introduced species (kumar and sane, 2003). p. santalinus is a small to medium sized deciduous tree having a dense, round crown reaching a height of 10 to 15 m with a girth of about 90 to 160 cm. the bark is typically dark brown in colour with rectangular plates and deeply fissured when matured. when blazed, it exudes a red colour gum with numerous pink streaks. the leaves are pinnately compound which are generally shed during january and march. with the onset of summer, new flush of leaves are produced along with large yellow coloured raceme flowers. due to prevailing dry and hot conditions in its natural habitat, the pollination ecology is vulnerable. as an endemic species, for its continuous survival, red sanders has devised cross pollination as the main system exhibiting xenogamous breeding though geitonogamy exists a bit (rao and raju, 2002).the matured reddish brown coloured winged pods are formed after eleven months of flowering and have one or two seeds (dayanand, 1988). in its natural habitat, the temperature varies from a minimum of 11 0 c to a maximum of 46 0 c and rainfall varying from as low as 100 mm to 1,000 mm indicative of the excessive dry climate prevailing throughout the year. the tree prefers growing in hilly terrain and their slopes and soils in general are shallow, poor, stony and well drained. about 82% of the natural population occurs in subsurface formation of quartzites indicating the soil preference for its growth (raju and nagaraju, 1999). it is a heavy light demander and avoids waterlogged areas. some of the important associated species of p. santalinus are pterocarpus marsupium, chloroxylon swietenia, hardwickia binata, anogeissus latifolia and albizia lebbeck). 2. uses the sapwood is white, heartwood is red to almost purplish black with streaks (purkayastha, 1996), the grains are interlocked, medium to fine textured, extremely strong, hard and heavy (air dried wood specific gravity ranges from 0.87 to 1.20) and is impregnated with reddish brown gum containing arunkumar and joshi /journal of tropical forestry and environment vol. 4. no 02 (2014) 1-10 3 red dye santalin. the timber seasons well and is immune to white ants and other insects (anonymous, 1969). red sanders wood has demand both in domestic and international markets. there are two types of wood that is popular in trade, one is wavy or ripple grained and the other is straight grained. the wavy grained wood has a huge demand in the international market and is primarily exported to japan for manufacturing a special musical instrument called as ‘shamisen’ a three stringed lute used in classical music as the wavy grained wood is supposed to have superior acoustic qualities. the neck of this instrument is primarily made by red sanders wood. it is also used to make name seals, frames, carving and traditional dishes. the musical instruments and other objects made out of this wood have been considered as an essential dowry given in a traditional japanese wedding (anonymous, 2014). historically, red sanders is used in china for the highly valued furniture being manufactured since tenth century. in china it is categorised under group of hardwood species designated as rosewood (hong mu). the rosewood furniture was used by ming and early qing dynasties and had special cultural significance. the two groups of rosewood zitan and huali are represented by pterocarpus santalinus and dalbergia odorifera, respectively (wenbin and xiufang, 2013). buddhists prefer this wood while cremating (ramakrishna, 1962). the straight grained wood is used for carving idols and toys. the timber is also used for house posts, agricultural implements, poles, shafts and bent rims of carts, boxes and picture frames. the leaf is used as a good fodder. red sanders wood has an important insoluble or sparingly soluble red wood dye. it contains 16% of the pigment santalin (santalic acid) a major colouring matter which was first isolated in a crude form in 1833. it is being used as a textile dye and has five colouring components ranging from violet to orange in colour but is popular for providing red colour (gulrajani et al., 2002; siva, 2003; ferreira et al., 2004). in european medicine, the red dye is used as a colouring agent while the french furniture makers used it for dyeing, polishing and varnishing during 1660 to 1885 (new, 1981). in usa, it is approved as a food dye for alcoholic beverages and approved as a food dye within europe and is classified as a spice extract rather than food colourant (mulliken and crofton, 2008). pterostilbene a methyl ester of resveratrol (3,5-dimethoxy-4'-hydroxy-trans-stilbene) was first isolated from red sanders (sheshadri, 1972) and has wide range of promising pharmacological properties (schmidlin et al., 2008). arunakumar et al. (2011) have extensively reviewed the phytochemical and pharmacological uses of p. santalinus. an interesting study on biogeochemistry reveals that heartwood and leaf of red sanders have the ability for elemental association and accumulation of various elements including rare earth elements. the accumulation of various elements is higher in heartwood and the range of strontium accumulation varied from 750 to 3,500 ppm. some of the other elements accumulated in the heartwood are cadmium (5 to 28 ppm), zinc (50 to 6,000 ppm), copper (105 to 1,025 ppm). among the various rare earth elements studied, the heartwood and leaves contained an average concentration of 1.22 and 0.03 ppm of uranium, respectively and the accumulation was higher in p. santalinus compared to p. marsupium and p. dalbergioides (raju and rao, 1998; raju and raju, 2000; raju and srinivasalu, 2008). siddhiraju (2013) reported that as p. santalinus has a narrow geographic and geological distribution, it can be used as a stratigraphic guide to recognize a group within the cuddapah super group. he also opined that all those geological formations that support the red sanders growth can be included under the cheyair group which has been abandoned by the geological survey of india in its latest classification. 4 3. red sanders in folklore/tribal medicine the heartwood has various uses in traditional medicines and is popular for the treatment of diabetes apart from other ailments. the wood paste is applied externally specially for healing various skin diseases and blemishes. yerukula and irula tribes of chittoor district in andhra pradesh use whole plant of p. santalinus for ulcer treatment (vedavathy et al., 1997). kandhas tribe in kandhamal district of orissa in india use the decoction of fresh stem barks of the plant, calamus tenuis root and azadirachta indica stem bark being given orally either with sugar candy or honey in empty stomach for 21 days to cure piles and blood setting piles (behera et al., 2006). it is also used by people of assam for healing skin diseases and as cosmetics. the wood is powdered and soaked in water and the paste is applied on skin for prickly heat. for smooth and fair skin, the powdered wood is mixed with flour and egg and is applied on the body (saikia et al., 2006). the stem bark extract is used by a tribal group of western ghats in shimoga region of karnataka state for treating diabetes, fever, snake bite and specially for jaundice. for treating acute jaundice, about one hundred grams of powdered stem bark is boiled in 500 ml of water for 3-4 hours till the volume is reduced to half the original content. the solution is cooled and then ten grams of jaggery is added and made into pills, two to three pills is administered every day for ten days (manjunatha, 2006). malamalasar tribe of perambikulam wildlife sanctuary in kerala considers wood paste as a blood purifier, for curing skin diseases and poisonous affections (yeshodharan and sujana, 2007). tripura ethnic community in hazarikhil, chittagong district of bangladesh, uses the stem sap by taking twice daily for three days to treat conjunctivitis (faruque and uddin, 2011). various tribes in coastal karnataka use red sanders as an anti inflammatory for the treatment of herpes (bhandari and chandrashekar, 2011). aborigines of kalahandi, orissa, use it as a blood purifier and diuretic. during chest pain and tuberculosis, paste is made from the wood and applied on the chest. also solution with water is made and taken for a month orally (panda and padhy, 2008). folklore claims in assam suggest that the seeds are used in herbal formulation as an antidote against bab (the poison, the origin of which is obscure), by karbis of anglong district of assam (teron and borthakur, 2013). 4. tree improvement in red sanders tree improvement activities in red sanders are similar to that of any other tree species. two commercially important traits that are to be considered while selecting superior genotypes as well as for conservation are, (a) wavy grain genotypes and (b) deep red heartwood. often described as ‘red gold’ and ‘pride of andhra pradesh’, several tree improvement activities have been carried out on this endemic species by forest department of andhra pradesh. it includes, establishing seed production area, clonal orchards and having identified 25 candidate plus trees. (reddy and srivasuki, 1992). 5. studies on wavy grain as mentioned earlier, wavy grained wood has gained prominence because of its export value. kedharnath et al. (1976), reported that the natural occurrence of wavy grain genotype is less than one per cent. they mentioned that tangential plane has more wavy grains than radial plane and the wood having wavy grains both tangentially and radially is valued. they also opined that waviness could be a genetic trait as wavy grain trees are seen in natural population as well as in plantations. red sanders has also been classified as quality and non quality variety on the basis of wavy grained and straight grained, respectively (raju and rao, 1987). in the field, wavy grain or straight grained trees are identified by removing a piece of bark wood such that the heartwood is visible and depending on the grain pattern, trees are designated as wavy or straight grained. arunkumar and joshi /journal of tropical forestry and environment vol. 4. no 02 (2014) 1-10 5 recognising the importance of wavy grain, and to identify, distinguish and select the wavy and straight grained trees, a scheme -studies on the genetic basis of wavy grain in red sanders and methods to increase the frequency of trees with wavy grainwas initiated at forest research institute, dehra dun. it was reported that lumen diameter was an important anatomical trait to screen for wavy grain at the sapling stage (kedharnath and rawat, 1976). some of the traits differentiating the wavy grain with that of straight grain were the presence of tyrosine in the vascular cambium, pericarp venation, seed and cotyledon shape and stomatal number (das and dayanand, 1983; 1984). it was also found that seedlings raised from wavy grained trees were slow growing compared to that of straight grained trees. the seedlings had short internodes, smaller and greener leaves, petioles and more compact crown and concluded that these traits were distinct and can be used for segregating the seedlings (rawat and uniyal, 1996). kedarnath (1984) found significant variation in waviness intensity from pith to periphery within and between trees. the physico-chemical characteristics difference revealed that wavy grained wood had 3 to 4% more of organo soluble and almost 50% less water soluble extractives compared to straight grained wood (theagarajan et al., 2004). raju and srinivasalu (2008) suggested that wavy grain trees has a preference for friable soils and are absent in compact soils or soils devoid of any soil cover. occurrence of both normal and wavy grained trees in the similar area suggests that genetic factors play a significant role along with environmental interactions. as the numbers of wavy grained trees are low, it is possible that gene for this character must be occurring in low frequency in the population or is controlled by polygenes. 6. studies on vegetative propagation reddy and srivasuki (1990) have summarised the various vegetative propagation methods such as grafting, air layering and rooting of cuttings carried out by the research wing of andhra pradesh forest department. micro propagation studies on red sanders began in 1980s. various authors used different explants to arrive at suitable plantlets. sarita et al. (1988) used single node and terminal cuttings for growing plantlets. sita et al. (1992) induced shoots from shoot tips and successfully transferred micropropagated plants to field. anuradha and pullaiah (1999) reported highest shoot bud regeneration by culturing mesophyll explants. arockiasamy et al. (2000) found that detached cotyledons from in vitro germinated seedlings were useful, while prakash et al. (2006) used nodal explants of young shoots. in-vitro germination studies carried out by chaturani et al. (2006) indicated that anderson medium was ideal for its establishment and suggested that the pods must be used within one week after harvest to obtain higher germination percentage. rajeshwari and paliwal (2008) reported successful micropropagation protocol through auxillary shoot proliferation by using cotyledonary nodes. nodal segments from in vitro regenerated shoots obtained from mature trees proliferated into multiple shoots (padmalatha and prasad, 2008). balaraju et al. (2011) induced multiple shoots by using shoot tip explants derived from 20 days old in vivo germinated seedlings and confirmed the genetic fidelity. warakagoda and subasinghe (2013) studied different explants and acclimatized the in vitro rooted plants. their technique can be used for mass propagation through micropropagation. 7. variability in red sanders padmalatha and prasad (2007) studied 16 accessions collected and found wide variation in genetic distance among the accessions as the rapd markers reflected a high level of dna polymorphism due to out crossing. using molecular markers as tool, rani and usha (2013) have developed sequence characterised amplified region (scar) marker for identification of quality (wavy grain) plants at seedling stage. they found that single sharp 1kb band was observed only in 6 wavy grained seedlings with pts-10 scar primer which was not amplified in case of non quality plants (straight grained). jyothi et al. (2014), reported that there are differences in the genomic dna quantity in the samples collected from different locations at andhra pradesh. significant variation was observed for height, girth and heartwood traits in a 20 year old red sanders plantation established in bangalore, karnataka. in case of heartwood content, it ranged from trees having no heartwood to trees having nearly 65% heartwood content. similarly, in case of a 45 year old plantation, the heartwood content varied from 6.18 to 81.95% indicating the enormous variation that exists in red sanders which also can be useful while selecting superior genotypes (arunkumar, 2011). padmalatha and prasad (2007) studied morphological variations in 16 accessions collected mostly from andhra pradesh and also from karnataka and kerala. distinct morphological variations were observed in pod (weight, width and length) characteristics, leaf characteristics (length, width), shoot length and number of nodes in five months old germinated seedlings. several aspects related to tree improvement have been initiated in red sanders. studies on genetic aspects related to wavy grain, heartwood variation and complete protocol for micro propagation still needs enormous refinement. being an endemic species, efforts to extend its cultivation in different regions are already initiated. 8. trade in red sanders red sanders wood is being extensively used as a tradable commodity since 16 th century when it was being exported to european countries. it is reported that during the five years ending at 1882-83, wood exported to united kingdom, france and indian and ceylon ports was 12,782, 1,116 and 1,687 tonnes, respectively, amounting to more than half a million rupees. observing the way it was being exploited ta whitehead, a forest officer in cuddapah wrote during the first decade of twentieth century that “not only the stems and branches but even the roots were extracted and is to be wondered at, that the tree has survived total extinction”. this observation has relevance even in the present days too. as mentioned earlier, the demand for the wood is more in international market. initially, in sixteenth century it was exported to european countries as a source for the natural dye which subsequently reduced as the synthetic dye came into the market, but japanese merchant in 1931 approached the forest department of andhra pradesh, rekindling the wood value in the international market. even though, p. santalinus has been documented in china by the jin dynasty scholar cui bao (265-340 ad), it was regarded as a rare and precious lignum as expensive as gold. presently, it costs around us$ 150,000 per m 3 (wenbin and xiufang, 2013). the heavy demand in international market for many centuries suggests why red sanders has been over exploited through illegal harvest. in its native state of andhra pradesh, during 2012-13, 1,488 forest offence cases have been booked for red sanders alone. along with it, 1002 vehicles accounting to 1,390 tonnes of wood have been seized (anonymous, 2014). the regular seizures of huge quantities of red sanders wood in international market are so common now that the survival and existence of p. santalinus is a cause for concern. adding to that, the frequent changing of the smuggling routes is also a challenge and needs a constant vigilance and efforts from all the neighbouring countries where red sanders has huge requirement. considering the wood demand, restricted distribution, slow regeneration, illegal harvest, trade and habitat destruction, the species has been categorized as endangered by iucn and has been listed in convention on international trade in endangered species of wild fauna and flora (cites). the cites aims at ensuring the survival of wild animals and plants being traded internationally and there by safeguarding the species being over exploited. on the basis of a proposal from india, pterocarpus arunkumar and joshi /journal of tropical forestry and environment vol. 4. no 02 (2014) 1-10 7 santalinus is the only species of pterocarpus that has been listed in appendix ii of cites on 16 th february 1995. appendix ii includes all species which although not necessarily now threatened with extinction may become so unless trade in specimens of such species is subject to strict regulation in order to avoid utilisation incompatible with their survival. the listing was annotated to cover – logs, wood-chips and unprocessed broken material which subsequently modified at cites cop 14 as logs, wood-chips, powder and extracts. in andhra pradesh, it is protected under the red sanders and sandalwood transit rules of the andhra pradesh forest act, 1967 and is also classified as a “reserved tree” under the andhra pradesh preservation of private forest rules, 1978. 13. future of red sanders p. santalinus is a resilient species and its survival amidst over exploitation from the past few centuries indicates that it is necessary to seriously think about its revival strategies. one of the best ways of conserving red sanders is not only to raise large scale seedling based plantations in its natural habitats but also in far away regions having similar growing conditions which would ensure that genetic material is safe for posterity. these plantations can also act as a source of plant material for initiating further tree improvement strategies. while growing red sanders outside the forest area, it is paramount to educate the tree growers to consider the gestation of the crop. usually, it is a tendency among growers to compare tree growing with agricultural crops, but on a long term basis the yield and the monetary benefits accrued by growing such valuable trees are definitely high. the government agencies must take a lead role to encourage the farmers and entrepreneurs to grow red sanders, as kukrety et al. (2013) suggested that, it is imminent to have a sustainable wood trade policy formulated by strongly incorporating stakeholder’s perceptions. therefore, to revive the past glory of this valuable species to mankind, government agencies, farmers, entrepreneurs and policy makers have to join hands together in protecting, conserving and sustainably utilizing red sanders. references anonymous. 1969. the wealth of india, publication and information directorate, csir, new delhi, india, 3: 305-306. anonymous. 2014. red alert on red sanders: sri lanka apprehends large consignment from india. traffic post, 20: 8-9. anuradha, m. and pullaiah, t. 1999. propagation studies of red sanders (pterocarpus santalinus l. f.) in vitro: an endangered taxon of andhra pradesh, india. taiwania, 44: 311-24. arockiasamy, s., ignacimuthu, s. and melchias, g. 2000. influence of growth regulators and explant type on in vitro shoot propagation and rooting of red sandal wood (pterocarpus santalinus l.). indian journal of experimental biology, 38: 1270-1273. arunkumar, a.n. 2011. variability studies in pterocarpus santalinus in different aged plantations of karnataka. my forest, 47(4): 343-353. arunakumara, k.k.i.u., walpola, b.c., subasinghe, s. and yoon, m.h. 2011. pterocarpus santalinus linn. f. (rath handun): a review of its botany, uses, phytochemistry and pharmacology. journal of the korean society for applied biological chemistry, 54: 495-500. balaraju, k., agastian, p., ignacimuthu, s. and park, k. 2011. a rapid in vitro propagation of red sanders (pterocarpus santalinus l.) using shoot tip explants. acta physiologiae plantarum, 33: 2501-2510. behera, s. k., panda, a., behera, s.k. and misra, m.k. 2006. medicinal plants used by the kandhas of kandhamal district of orissa. indian journal of traditional knowledge, 5: 519-528. bhandari, m.j. and chandrashekar, k. r. 2011. herbal therapy of herpes in the ethnomedicine of coastal karnataka. indian journal of traditional knowledge, 10(3): 528-532. 8 chaturani, g.d.g., subasinghe, s. and jayatilleke, m.p. 2006. in-vitro establishment, germination and growth performance of red sandalwood (pterocarpus santalinus l.). tropical agricultural research and extension, 9: 116-130. chauhan, l. and vijendra rao, r. 2003. wood anatomy of the legumes of india. their identification, properties and uses. bishen singh mahendra pal singh, dehra dun, india. das, t.l. and dayanand, t. 1983. amino acid composition in wavy-grained and straight grained trees of red sanders (pterocarpus santalinus linn. f.). indian journal of forestry, 6: 158-159. das, t.l. and dayanand, t. 1984. some distinguishing characteristics between wavy grained and straight grained trees of red sanders pterocarpus santalinus. indian journal of forestry, 7: 6971. dayanand, t. 1988. studieson development and maturity of pod in red sanders (pterocarpus santalinus). indian journal of forestry, 11(3): 207-208. faruque, o. and uddin, s.b. 2011. ethnodiversity of medicinal plants used by tripura community of hazarikhil in chittagong district of bangladesh. j. taxon. biodiv. res., 5: 27-32. ferreira, e.s.b., alison, n., hulme, a.n., hamish, mcnab, h. and quye, a. 2004. the natural constituents of historical textile dyes, chemical society reviews, 33: 329-336. goi (government of india). 2014. government of india. ministry of environment of forests publications. red sanders. available at http://moef.nic.in/downloads/public-information/chap8-new.pdf [accessed on 24 may 2014]. gulrajani, m.l., bhaumik, s., oppermann, w. and hardtmann, g. 2002. kinetic and thermodynamic studies on red sandalwood. indian journal of fibre and textile research, 27: 91-94. jyothi, c.p., chandrashekar, r. and lakshmi, b. 2014. isolation of pterocarpus santalinus l. genomic dna, for quality check and quantification with reference to telangana region, andhra pradesh, india. indian journal of science, 8: 21-24. kedharnath, s. 1984. forest tree improvement in india. (in) proceedings of indian academy of science (plant science), 93: 401-412. kedharnath, s. and rawat, m.s. 1976. studies on variation in fibre morphology in wavy grained and straight grained trees of red sanders. indian forester, 102: 441-446. kedharnath, s., rawat, m.s., uniyal, d.p. and kantham, d.l. 1976. studies on field grafting and the growth of grafts in red sanders. indian forester, 102: 761-765. klitgaard, b.b. and lavin, m. 2005. the tribe dalbergieae sens. lat. in: g. lewis, b. schrire, b. mackinder & m. lock (eds.), legumes of the world. royal botanic gardens kew, london. kukrety, s., jose, s. and alavalapati, j.a.a. 2013. exploring stakeholders’ perceptions with analytic hierarchy process: a case study of red sanders (pterocarpus santalinus l.) restoration in india. restoration ecology, 21(3): 372-379. kumar, s. and sane, p.v. 2003. legumes of south asia, a check-list. royal botanic gardens, kew, london. lakshminarasimhan, p. and mondal, m.s. 2012. a pictorial guide to some of the indian plants included in the cites and negative list of exports. botanical survey of india, howrah, pp.22-24. manjunatha, b.k. 2006. hepatoprotective activity of pterocarpus santalinus l. f., an endangered plant. indian journal of pharmacology, 38: 25-28. mulliken, t. and crofton, p. 2008. review of the status, harvest, trade and management of seven asian cites-listed medicinal and aromatic plant species. http://www. cites.org/common/ com/pc/17/x-pc17-inf-10.pdf. new, s. 1981. the use of stain by furniture makers: 1660 to 1885. furniture history, 17: 51-60. arunkumar and joshi /journal of tropical forestry and environment vol. 4. no 02 (2014) 1-10 9 padmalatha, k. and prasad, m.n.v. 2007. morphological and molecular diversity in pterocarpus santalinus l.f: an endemic and endangered medicinal plant. medicinal and aromatic plant science and biotechnology, 1: 263-273. padmalatha, k. and prasad, m.n.v. 2008. in vitro plant regeneration of pterocarpus santalinus l.f (red sanders): an endangered medicinal plant and important timber tree. tree and forestry science and biotechnology, 2: 1-6. panda, t. and padhy, r.n. 2008. ethnomedicinal plants used by tribes of kalahandi district, orissa. indian journal of traditional knowledge, 7: 242-249. prakash, e., khan, p.s.s.v., rao, t.j.v.s. and meru, e.s. 2006. micropropagation of red sanders (pterocarpus santalinus l.) using mature nodal explants. journal of forest research, 11: 329335. prasad, r.c.p., reddy, c.s., raza, s h. and dutt, c.b.s. 2008. population structure, age gradations, and regeneration status of pterocarpus dalbergioides roxb, an endemic species of andaman islands, india. the pacific journal of science and technology, 9: 658-664. purkayastha, s.k. 1996. a manual of indian timbers. sribhumi publishing company, calcutta, india, pp.251. rajeswari, v. and paliwal, k. 2008. in vitro plant regeneration of red sanders (pterocarpus santalinus l.f.) from cotyledonary nodes. indian journal of biotechnology, 7: 541-546. raju, k.k. and nagaraju, a. 1999. geobotany of red sanders (pterocarpus santalinus): a case study from the southeastern portion of andhra pradesh. environmental geology, 37: 340–344. raju, k.k. and raju, a. n. 2000. biogeochemical investigation in south eastern andhra pradesh: the distribution of rare earths, thorium and uranium in plants and soils. environmental geology, 39(10): 1102-1106. raju, k.k., raju, a.n. and sudheer, a.s., 1999. biogeochemistry of red sanders from southeastern part of andhra pradesh, south india. fresenius environmental bulletin, 8(3-4): 204–212. raju, k.k. and rao, j.r. 1988. red sander: an accumulator plant of strontium, geobios, v.15 pp. 207-209. raju, k.k., rao, j.r. 1987. distribution of red sanders using the geological formations in cuddapah landscape. indian journal of forestry, 10: 264266. raju, k.k. and srinivasulu, s. 2008. the red sanders forestry: an environmental appraisal towards an effective legislation. proceedings of ecocity world summit 2008, san francisco, california, usa. ramakrishna, a. the red sanders and its future. indian forester, 88: 202-206. rani, j.s. and usha, r. 2013. development of rapd and specific scar markers for the identification of pterocarpus santalinus. l. journal of cell and tissue research, 13(3): 3809-3816. rao, s.p. and raju, a.j.s. 2002. pollination ecology of the red sanders pterocarpus santalinus (fabaceae), an endemic and endangered tree species. current science, 83: 1144-1148. rawat, m.s. and uniyal, d.p. 1996. identification of wavy grained red sanders (pterocarpus santalinus) at nursery state. indian forester, 122: 831-3. reddy, k.k. and srivasuki, k.p. 1990. vegetative propagation of red sanders (pterocarpus santalinus linn.). indian forester, 116: 536-40. reddy, k.k., srivasuki, k.p. 1992. biotechnological approach for tree improvement in red sanders. indian forester, 118: 15-20. saikia, a.p., ryakala, v.k., sharma, p., goswami, p. and bora, u. 2006. ethnobotany of medicinal plants used by assamese people for various skin ailments and cosmetics. journal of ethnopharmacology, 106: 149-157. 10 sarita, s., bhatnagar, s.p. and bhojwani, s.s. 1988. preliminary investigations on micropropagation of leguminous timber tree pterocarpus santalinus. phytomorphology, 38: 41-45. saslis-lagoudakis, c.h., klitgaard, b.b., forest, f., francis, l., savolainen, v., williamsons, e.m. and hawkins, j.a. 2011. the use of phylogeny to interpret cross-cultural patterns in plant use and guide medicinal plant discovery: an example from pterocarpus (leguminosae). plos one, 6(7): 10.1371/journal.pone.0022275. schmidlin, l., poutaraud, a., claudel, p., mestre, p., prado, e., santos-rosa, m., wiedemannmerdinoglu, s., karst, f., merdinoglu, d. and hugueney, p. 2008. a stress-inducible resveratrol o-methyltransferase involved in the biosynthesis of pterostilbene in grapevine. plant physiol., 148(3): 1630-1639. seshadri, t.r. 1972. polyphenols of pterocarpus and dalbergia woods. phytochemistry, 11: 881–898. siddi raju, s. 2013. red sanders as a stratigraphic guide in the correlation of the cuddapah formations. international journal of scientific research, 2(2): 87-89. sita, l.g., sreenatha, k.s. and sujata, s. 1992. plantlet production from shoot tip cultures of red sandalwood (pterocarpus santalinus l.). current science, 62: 532–535. siva, r. 2003. status of natural dyes and dye-yielding plants in india. current science, 92: 916-925. teron, r. and borthakur, s.k. 2013. folklore claims of some medicinal plants as antidote against poisons among the karbis of assam, india. pleione, 7: 346-356. theagarajan, k.s., prabhu, v.v., shankaranarayana, k.h. and ravikumar g. 2004. physico chemical characteristics of wavy and straight grained red sanders. journal of indian academy of wood science, 1: 7-10. vedavathy, s., sudhakar, a. and mrudula, v. 1997. tribal medicinal plants of chittoor ancient. science of life, 26: 307-331. warakagoda, p.s. and subasinghe, s. 2013. in vitro propagation of pterocarpus santalinus l. (red sandalwood) through tissue culture. journal of the national science foundation of sri lanka, 41(1): 53-63. wenbin, h. and xiufang, s. 2013. tropical hardwood flows in china: case studies of rosewood and okoumé. forest trends association, washington dc, usa. yeshodharan, k. and sujana, k.a. 2007. ethnomedical knowledge among malamalasar tribe of perambikulam wildlife sanctuary, kerala. indian journal of traditional knowledge, 6(3): 481485. madurapperuma & kuruppuarachchi/journal of tropical forestry and environment vol. 4, no 01 (2014) 50-58 50 detecting land-cover change using mappable vegetation related indices: a case study from the sinharaja man and biosphere reserve b.d. madurapperuma 1* and k.a.j.m. kuruppuarachchi 2 1 department of forestry and natural resources, purdue university, west lafayette, in 47906, usa 2 department of botany, the open university of sri lanka, nawala, nugegoda, sri lanka date received: 04-10-2013 date accepted: 05-04-2014 abstract understanding the effects of human disturbances at the forest fringe is useful in efforts to implement best management practices aimed at conserving forest resources. this study evaluates multi-year changes of vegetation in the sinharaja man and the biosphere (mab) reserve using mappable vegetation related indices viz., normalized difference vegetation index (ndvi) and burn index (bi). land-cover changes in the sinharaja mab reserve were detected using landsat 7 etm + images for 1993, 2001, and 2005, and diva gis land-cover data in 2000. ndvi resulted in a 962 ha increase of vegetation prime at the western sinharaja from 2001-2005 and a 15 ha decrease of vegetation at the southern sinharaja from 1993-2005. results from bi showed that the sinharaja mab reserve fringe is vulnerable to forest fire. this vulnerability can be seen in the following totals of burned hectares: 160 ha from 1993-2001, 79 ha from 2001-2005, and 10 ha for the entire period of 1993-2005. according to the land-cover map, burn area occurred at the cultivated lands, scrublands, and fragmented forest fringe. the results were visualized using an embedded 3d render window of google earth and a 2d view of arcgis explorer online. in conclusion, insitu ground truthing data is needed for the fire-influenced area for implementing sustainable forest resource management at the sinharaja mab reserve. keywords: burn index, google earth, mapping, ndvi, sinharaja mab reserve ___________________________________________________________________________ 1. introduction the southwestern region in sri lanka is a showcase for biodiversity, where lowland rainforests harbour high endemic and threaten taxa (gunatilleke & gunatilleke, 1991). for example, the sinharaja rainforest, the largest primary rainforest in sri lanka, contributed over 60% endemic flora (gunatilleke & gunatilleke, 1996; gunatilleke et al., 2005) and 23% endemic vertebrate fauna (de zoysa & raheem, 1990). even though the sinharaja forest reserve contributes a mere 13% of the protected forests in the wet zone, despite its biological wealth, it was declared a national heritage wilderness area in 1988 (ncr, 1997). prior to being declare a protected forest natural resources were extracted at an alarming rate. the sinharaja forest reserve has been primarily disturbed through logging for supplying timber for the plywood industry between 1972 and 1977 (sri bharathie, 1979; ncr, 1997). in 1977, logging operations were ceased and the degraded area was included in the forest reserve. * correspondence: bmadurap@purdue.edu tel: +1 7654094382 issn 2235-9370 print/issn 2235-9362 online © university of sri jayewardenepura madurapperuma & kuruppuarachchi/journal of tropical forestry and environment vol. 4, no 01 (2014) 50-58 51 human induced disturbances such as, shifting cultivation, extraction of non-timber forest products, and human encroachment were found at the forest fringe of sinharaja (de zoysa et al., 1989; mcdermott et al., 1990; gunatilleke, 1998). the rural communities, who live proximity to the sinharaja forest depend on the forest resources to meet their subsistence and income needs (gunatilleke et al., 1993; kathriarachchi et al., 2004). therefore, creating wildness areas at the human-forest interface is useful not only for protecting forest resources from disturbances, but also beneficial for local communities. collaboration with village communities is vital for implementing sustainable forest management programs in order to protect the government forest. the sinharaja rainforest exists within a 3 km wide buffer zone, which reduces human encroachment especially from tea and rubber plantations (gunatilleke & gunatilleke, 1985; wijesooriya & gunatilleke, 2003). understanding landscape patterns and processes, which are influenced by human activities and/or natural phenomenon is essential for proper land management and policymaking (prakasam, 2010). however, there are major gaps in knowledge on how spatially constrained forest cover change over time. this knowledge is useful to understand the significance of habitat fragmentation, which causes edge effects resulting in biodiversity loss. this study assesses the changes of vegetation in sinharaja that were caused by selective logging and slash and burn cultivation (gunatilleke & gunatilleke, 1985). therefore, it is important to assess post-disturbance recovery of the sinharaja forest in terms of spatial and temporal perspectives. we hypothesized that the fire intensity at the sinharaja buffer zone is high compared to the core region that contributes significant vegetation reduction at the forest fringe. the research questions addressed in this paper were: (i) how the land-cover has changed in sinharaja from 1993 to 2005 (ii) how the fire has impacted the forest reserve and the buffer zone over the 12 years the answers for these questions will eventually provide insight for sustainable forest management and policy making for the conservation of the sinharaja mab reserve. study site the sinharaja mab reserve is situated in the south-west lowland wet zone of sri lanka within the sabaragamuwa and southern provinces (6°21'-6°26'n, 80°21'-80°34'e) that span over the administrative boundaries of rathnapura, galle and matara (fig. 1). the total extent of 11,187 ha has been legally protected as a core region of sinharaja mab with a 3 km external buffer zone (bandaratilleke, 1992; ncr, 1997). sinharaja is a primary forest comprised of mixed dipterocarp and lower montane forest, which extends across an altitudinal range of 210 to 1,180 m (gunatilleke et al., 1996). the mean annual rainfall in sinharaja ranges from 3,600 to 5,000 mm and the temperature varies between 19 0 and 27 0 c. madurapperuma & kuruppuarachchi/journal of tropical forestry and environment vol. 4, no 01 (2014) 50-58 52 fig. 1: study area map showing the sinharaja mab reserve and administrative boundaries. 2. materials and methods landsat 7 etm + images of the study area were acquired from the global land cover facility web portal (http://glcf.umd.edu/data/landsat/). these images were acquired over the span of three different years viz., 1993, 2001 and 2005. the details of the acquired images, including the worldwide reference system (wrs), path, and row information are given by table 1. the images are on a scale of 30 m spatial resolution. seven individual bands of each image were converted to new multiband files by layer stacking using envi ® 4.5. then the multiband files were re-projected to utm zone 44 north, wgs-84 datum. table 1: landsat time series scenes used in the study. satellite date sensor resolution wrs path row landsat 7 landsat 7 landsat 7 12/02/1993 14/03/2001 05/02/2005 etm+ etm+ etm+ 30 m 30 m 30 m 2 2 2 141 141 141 56 56 56 thereafter, each data set was exported to envi ® ex environment and an image difference tool was used to detect the changes between the 1993 to 2005 time steps based on the normalized difference vegetation index (ndvi) and normalized difference burn index (ndbi). ndvi measures seasonal and inter-annual changes in vegetation growth and activity (jensen, 2005). ndvi is functionally equivalent to simple band ratios of etm images and can be described by the following equation (1): ndvi = (ρnir ρred)/ (ρnir + ρred) (1) where: ρnir = spectral reflectance for band 4 ρred = spectral reflectance for band 3 ndbi measures burn severity in terms of simple band ratios of etm bands 4 and 7 and is given by equation (2). those bands exhibited the greatest reflectance change in response to fire (key et al., 2002). madurapperuma & kuruppuarachchi/journal of tropical forestry and environment vol. 4, no 01 (2014) 50-58 53 ndbi = (ρ band4 ρ band7)/ (ρ band4 + ρ band7) (2) where: ρ band4 = spectral reflectance for band 4 ρ band7 = spectral reflectance for band 7 each ndvi and ndbi data were imported to virtual globes such as google earth and arcgis online platforms to create change detection maps of the study area. google earth is a powerful mapping software, which can be used to visualize three-dimensional representations of terrain topography. similarly, arcgis online platforms were used to visualize landscape changes over time with layers of road, rivers and administrative boundaries of the study area. the villages within the sinharaja mab reserve were obtained from the diva gis web portal (http://www.diva-gis.org/data) and 500 m buffer zones were created in each village. then vegetation-changed results were compared within the 500 m buffer zones. 3. results this study assesses land-cover change in the sinharaja mab reserve over 12 years, spanning the periods of 1993-2001, 2001-2005 and 1993-2005, using mappable vegetation related indices, such as ndvi and ndbi. the vegetation growth showed a 962 ha increase of vegetation prime at the western sinharaja in 2001-2005 (fig. 2). in addition, a 15 ha area of vegetation decreased at the sourthern sinharaja from 1993 to 2005. fig. 2: land-cover change detection using ndvi and ndbi indices in the sinharaja forest reserve from 1993 to 2005. madurapperuma & kuruppuarachchi/journal of tropical forestry and environment vol. 4, no 01 (2014) 50-58 54 results of the burn index showed that the sinharaja mab reserve fringe was vulnerable to forest fire compared to the co-region of the sinharaja mab reserve. for example, the 1993 image compared to the 2001 image revealed 160 ha burned. the 2001 image compared to the 2005 image showed 79 ha burnt. for the entire period, the 1993 image compared to 2005 image revealed 10 ha burnt. the sinharaja mab reserve is governed by 41 villages, which are located inside a three-kilometer buffer within the reserve’s boundary (table 2, fig. 2). these 41 villages represent three provinces viz., sabaragamuwa, southern and western. the villagers represented four districts including: 32 villages from rathnapura, 7 villages from galle, 1 village each, matara and kalutara. of the villages, mannawatta (western sinharaja) and kolontotuwa (sourthern sinharaja) showed a ndvi increased between 2001 and 2005. in contrast, koskulana ganga, napala dola, kekillapitiya, warukandeniya, pelawatta and tambalagama observed a ndbi decrease between 1993 and 2005. table 2: villages in the provinces of sabaragamuwa (sa), southern (so) and western (we) and in the districts of the rathnapura (ra), galle (ga), matara (ma) and kalutara (ka) in the sinharaja forest reserve. village name division & district village name division & district bambarabotuwa sa, ra pelawatta sa, ra calton hill sa, ra petha dola sa, ra denuwakanda sa, ra pethiyakanda sa, ra diyapotagam pattuwa sa, ra petiyakanda sa, ra dolahena sa, ra pitakele sa, ra edandu ela sa, ra pitigalakanda sa, ra egodakanda sa, ra rawreth sa, ra gamagepetta sa, ra rew sa, ra gongala sa, ra sinna caldone sa, ra hapugoda sa, ra tangamale plains sa, ra heen dola sa, ra wewagama sa, ra ittekanda sa, ra aranuwa dola so, ga kekillapitiya sa, ra gigurawa ihala so, ga kongahakanda sa, ra gigurawa pahala so, ga koskulana ganga sa, ra kolontotuwa so, ga kudawe sa, ra kosmulla so, ga kudawe ganga sa, ra tambalagama so, ga maha ganga sa, ra warukandeniya so, ga morningside sa, ra abbey rock so, ma napala dola sa, ra mannawatta we, ka okehampton sa, ra source: data was acquired from diva gis web portal gazetteer the results of vegetation growth and the burned area are visualized using an embedded 3d render window of google earth (fig. 3). the results showed that the periphery of the forest reserve is vulnerable to forest fire. disturbances of fire on sites were clearly visible from google earth when maps zoomed into a particular area. the conspicuous madurapperuma & kuruppuarachchi/journal of tropical forestry and environment vol. 4, no 01 (2014) 50-58 55 vegetation growth in the forest reserve was observed in the kalutara district in 2001-2005 (figs. 2 & 3). a land-use/cover map for the sinharaja mab reserve was created using diva gis data, which originary derived from global land cover data in 2000 at 1 km spatial resolution (fig. 4). table 3 summarizes the extent of land-use/cover within the sinharaja reserve boundary. generally, co-areas of sinharaja mab reserve are comprised of evergreen forest and some periphery areas are converted to croplands or shrubland. for example, 93% of the area is evergreen forest, while 6% is comprised of cultivated and/or managed areas. fig. 3: google earth view of the study area showing vegetation changed areas at the sinharaja forest reserve fringe. the overview map zoomed into an area of ndvi decreased. fig. 3: google earth view of the study area showing vegetation changed areas at the sinharaja forest reserve fringe. the overview map zoomed into an area of ndvi decreased. fig. 4: land-use/cover types at the sinharaja forest reserve and suburbs. land-use/cover data were acquired from diva gis web portal. madurapperuma & kuruppuarachchi/journal of tropical forestry and environment vol. 4, no 01 (2014) 50-58 56 table 3: extent of land-use/cover within the sinharaja reserve boundary. landuse cover area, ha proportion, % tree cover, broadleaved, evergreen tree cover, broadleaved, deciduous, closed shrub-cover, closed-open, evergreen cultivated and managed 24,288 86 173 1,615 92.84 0.33 0.66 6.17 4. discussion this study shows how anthropogenic disturbances change vegetation in the sinharaja mab reserve, when an area is exposed to a historic fire scenario. vegetation changes can be detected using ndvi, which reflects a habitat’s health or a habitat’s condition in given sites (jayasuriya et al., 2009). for example, ndvi increase denotes vegetation growth such as canopy green-up, whereas ndvi decrease signifies forest fire or defoliation. according to our results on vegetation growth, or ndvi, increases can be conspicuous at the core region of the sinharaja forest. the vegetation growth that clustered at the western sinharaja could possibly be a result of secondary vegetation growth, resulting from selected logging during 1970’s. compared to old growth forest, this secondary forest could simulate leaf flushing on the canopy with a green-up. in contrast, ndvi decrease sites were in proximity to the burn sites, indicating that the slash and burn cultivation caused vegetation to decrease in sinharaja. in addition, vegetation decrease areas in the sinharaja buffer zone could be tea cultivated lands (wijesooriya & gunatilleke, 2003). similarly, kanneliya forest reserve, which is a neighbouring forest to the sinharaja forest reserve, experienced forest degradation due to tea cultivation resulting in scrublands (lindström et al., 2012). habitat alterations resulting from adjacent land-use practices, in proximity to the sinharaja forest boundary, grow towards the forest. for example, cropland and shrubland land-use types were observed within the forest reserve fringe (fig. 5). this scenario leads to forest degradation such as: bottom-up effects (i.e. forest clearance for groundstory cardamom cultivation) and top-down effects (i.e. selective logging) (ashton et al., 2001). villages in proximity to the sinharaja forest may demand forestlands for crop cultivation, resource extraction, forest clearance and cultivation (surasinghe, 2004). therefore, it is essential to introduce new land management policies to forest dwelling communities to conserve forest resources. pinus caribaea plantations were established between 1978 and 1982 at the abandoned shifting cultivation lands of the sinharaja buffer zone (shibayama et al., 2006) for forest gap management. shibayama et al. (2006) suggested that groundstory fire at the pinus caribaea plantations resulted in low diversity of trees and vines. furthermore, they recommended groundstory fire protection for the p. caribaea plantation for best restoration management. in this study, we recommend to conduct a ground truthing survey for the burned areas in order to find the species compositional change resulting from historic fire scenario’s. this would eventually provide valuable baseline information for the restoration of degraded lands in sinharaja. we found that six villages out of 41 villages are located at the fire-influenced sites within the 500 m buffer zone. therefore, forest stewardship programs, in collaboration with local communities living at the disturbed forest areas, would eventually provide better forest conservation strategies. for example, it can introduce agroforestry systems to the villages, while introduce multipurpose tree species to enhance the livelihood of the local communities. madurapperuma & kuruppuarachchi/journal of tropical forestry and environment vol. 4, no 01 (2014) 50-58 57 moreover, abandoned agricultural lands at the forest fringe can be managed, through the low cost-simple silvicultural method (popham, 1993; dilhan et al., 2010), to convert secondary forest. then those rehabilitated forests fragments can be used to link with the existing natural forest through restoration corridors. small-scale community based organizations are useful for making local communities aware of forest resources and restoration programs, and the communities can implement participatory forest management programs (lindström et al., 2012). the forest can be valuated by the ecosystem function of the tropical forests through carbon budgeting, and the sinharaja mab reserve may be ranked at the top for its carbon sequestration. the developed countries can make incentives to protect the natural forests, in terms of reducing ghg emissions that could be beneficial for local communities who are enrolling for the forest management programs. concurrently, the forest department can initiate a spatial analyst project to identify and spatially display vulnerable forestlands in the sinharaja to make decisions and plan support systems to implement new policies for conservation. references ashton, m.s., gunatilleke, c.v.s., singhakumara, b.m.p., gunatilleke, i.a.u.n., 2001. restoration pathways for rain forest in southwest sri lanka: a review of concepts and models. forest ecology & management, 154:409-430. bandaratilleke, h.m., 1992. managing the buffer zone in sinharaja world heritage forest. parks, the international magazine dedicated to the protected areas of the world, 3:15-19. de zoysa, n.d., gunatilleke, c.v.s., gunatilleke, i.a.u.n., 1989. secondary vegetation on an abandoned shifting cultivation site in the sinharaja forest. the sri lanka forester, 19:3-16. de zoysa, n., raheem, r., 1990. sinharaja, a rain forest in sri lanka, colombo, sri lanka, march for conservation. dilhan, m.a.a.b., amarasinghe, j., wijewardene, d.n.n., 2010. building sustainable botanic gardens: a simple silvicultural method adopted to haven certain wood trees into productive arboretum in the dry zone of sri lanka, proceedings of the fourth global botanic gardens congress, dublin, national botanic gardens of ireland, pp.14. gunatilleke, c.v.s., gunatilleke, i.a.u.n., 1985. phytosociology of sinharaja-a contribution to rain forest conservation in sri lanka. biological conservation, 31:21-40. gunatilleke, c.v.s., gunatilleke, i.a.u.n., 1991. threatened woody endemics of the wet lowlands of sri lanka and their conservation. biological conservation, 55:17-36. gunatilleke, c.v.s., gunatilleke, i.a.u.n., 1996. sinharaja: world heritage site, national science foundation, colombo, sri lanka. gunatilleke, c.v.s., gunatilleke, i.a.u.n., abeygunawardena, p., 1993. interdisciplinary research towards management of non-timber forest resources in lowland rain forests of sri lanka. economic botany, 47:282-290. gunatilleke, c.v.s., perera, g.a.d., ashton, p.m.s., ashton, p.s., gunatilleke, i.a.u.n., 1996. seedling growth of shorea section doona (dipterocarpaceae) in soils from topographically different sites of sinharaja rain forest in sri lanka, in: swaine, m.d., (ed.), man and the biosphere series, unesco, paris, parthenon publishing, carnforth, uk, pp 245-263. http://www.bgci.org/files/dublin2010/papers/dilhan-m-a-a-b.pdf madurapperuma & kuruppuarachchi/journal of tropical forestry and environment vol. 4, no 01 (2014) 50-58 58 gunatilleke, i.a.u.n., gunatilleke, c.v.s., dilhan, m.a.a.b., 2005. plant biogeography and conservation of the south-western hill forests of sri lanka. the raffles bulletin of zoology, 12:9-12. gunatilleke, h.m., 1998. the role of rural development in protecting tropical rainforests: evidence from sri lanka. journal of environmental management, 53:273-292. jayasuriya, a.h.m., kitchener, d.j., biradar, c.m., 2009. variability status of biosphere reserves in sri lanka. journal of national science foundation sri lanka, 37:7-24. jensen, j. 2005. remote sensing of the environment: an earth resource perspective. 2 nd ed. pearson education inc. kathriarachchi, h.s., tennakoon, k.u., gunatilleke, c.v.s., gunatilleke, i.a.u.n., ashton, p.m.s., 2004. ecology of two selected liana species of utility value in a lowland rain forest of sri lanka: implications for management. conservation and society, 2:273-288. key, c.h., zhu, z., ohlen, d., howard, s., mckinley, r., benson, n., 2002. the normalized burn ratio and relationships to burn severity: ecology, remote sensing and implementation, in: greer, j.d. (ed.), rapid delivery of remote sensing products. proceedings of the ninth forest service remote sensing applications conference, san diego, american society for photogrammetry and remote sensing, bethesda, md. lindström, s., mattsson, e., nissanka, s.p., 2012. forest cover change in sri lanka: the role of small scale farmers. applied geography, 34:680-692. mcdermott, m., gunatilleke, c.v.s., gunatilleke, i.a.u.n., 1990. the sinharaja rain forest: conserving both biological diversity and a way of life. the sri lanka forester, 19:322. national conservation review [ncr]. 1997. designing an optimum protected areas system for sri lanka's natural forests, vol. 1. iucn/fao. popham, f. h., 1993. dambulla. a sanctuary of tropical trees. sam popham foundation, uk. prakasam c. 2010. land use and land cover change detection through remote sensing approach: a case study of kodaikanaltaluk, tamilnadu. international journal of geo matics and geosciences, 1:150-158. shibayama, t., ashton, m.s., singhakumara, b., griscorm, h.p., ediriweera, s., griscom, b.w., 2006. effects of fire on the recruitment of rain forest vegetation beneath pinus caribaea plantations, sri lanka. forest ecology &d management, 226:357-363. sri bharathie, k.p., 1979. natural regeneration in the exploited section of the sinharaja reserve. the sri lanka forester, 14:41-42. surasinghe, t.d., 2004. distribution and habitat selection of agamid lizards in the sinharaja man and biosphere reserve, b.sc. dissertation, university of colombo, sri lanka. wijesooriya, w.a.d.a., gunatilleke, c.v.s., 2003. buffer zone of the sinharaja biosphere reserve in sri lanka and its management strategies. journal of national science foundation sri lanka, 31:57-71. dissanayaka and wijayaratne/ journal of tropical forestry and environment vol. 10 no. 02 (2020) 51-58 _____________________________________________ *correspondence: wollylk@yahoo.com tel: +94 775707079 © university of sri jayewardenepura 51 common agricultural practices and post-harvest losses in trincomalee, sri lanka d.m.s.k. dissanayaka and l.k.w. wijayaratne* department of plant sciences, faculty of agriculture, rajarata university of sri lanka, anuradhapura, sri lanka date received: 19-11-2020 date accepted: 20-12-2020 abstract in sri lanka, the post-harvest losses of harvested crop yield has become a national issue in terms of food security and nutrition. different types of losses occurred during the storage of various crops are frequently reported throughout the country. despite the awareness on increased post-harvest losses in warm environmental conditions and geographical-area-based crop losses, recent information on such post-harvest losses of crops grown in different regions of sri lanka is not available. therefore, this study assessed the crop cultivation practices, main crops grown and their post-harvest losses in two different areas adopt traditional farming (mahadiwulwewa) and urbanised agriculture (nilaweli) in trincomalee district of sri lanka. data were collected from farmer families using a questionnaire. the main crop cultivated in both mahadiwulwewa than nilaveli is paddy. however, farmers in nilaveli extend their cultivation to field crops, vegetables and fruits tobacco. in both mahadiulwewa and nilaveli, the majority of farmers engaged in farming between 50-59 years of age. paddy occupied 73% of the total cultivated area in nilaveli and 100% in mahadiwulwewa. the average yield and use of machineries differed with the crop. storage duration of paddy was 3-6 months. for storage of paddy, mostly farmers use jute sack and gunny bags. post-harvest losses occurred during storage and insect infestation is also discussed. the information on numerous agricultural practices in the selected areas would help to improve the existing practices and minimise the losses targeting better agricultural productivity in trincomalee district in the future. keywords: farming practices, paddy, other crops, storage losses, insects 1. introduction the post-harvest losses of crop yield across the world is estimated to be about 1.3 billion ton or onethird of the total food production, and is a great challenge to the global food security (kumar and kalita, 2017). such losses can be occurred at any stage from harvesting of crop yield until consumption (hill, 1992; hagstrum and subramanyam, 2006). the influence of various factors on postharvest losses has been reported throughout the world (african post harvest losses information system, 2011; khare, 2015). furthermore, the losses can be minimised through the utilisation of improved technology (baributsa, 2012; baoua et al., 2012). post-harvest losses of agricultural commodities vary with the geographical location (mvumi and stathers, 2014; kumar and kalita, 2017; wijayaratne et al., 2018). in sri lanka, the last island wide survey on postharvest losses has been done two decades ago (palipane, 2001) necessitating the requirement to have updated knowledge. in another old study, the losses of paddy in storage systems used in sri lanka has been evaluated (donahaye et al., 1991). while there has been no comprehensive survey done representing entire sri lanka on these losses in the recent past, individual records from different geographical regions still provide important data on the crop post-harvest losses. as such, post-harvest losses of paddy, maize and greengram in anuradhapura district were made available recently (kumari et 52 al., 2020). the post-harvest deterioration is high at higher temperatures (hagstrum and subramanyam, 2006). however, there has been a scarcity of such information recorded from the warmer areas of sri lanka including the north and eastern parts of the country. therefore it is worth surveying the nature of crop losses following harvest in the other warmer parts of the country. the dry zone of the sri lanka bears 11 agro-ecological sub-regions with different climatic characteristics. the agro-ecological sub-regions (dl1c, dl1d, dl1e) belong to eastern part of the dry zone have unique rainfall pattern. the agricultural practices in these areas are highly adaptive to this unique rainfall pattern (bio diversity clearing house mechanism, 2016-2017). trincomalee located in the northeast area of sri lanka belongs to the dl agro-ecological zone. trincomalee district bears population of 426,000 dispersed in land area of 2,529 km2 possessing their main occupation as crop farming. due to the limited water supply mostly coincides with the rainfall pattern, the crops are cultivated on seasonal basis in trincomalee (basic population information on trincomalee district, 2007). rice is the staple food of sri lankans (waisundara, 2020). furthermore, the contribution from upland crops to the national production is also important in terms of nutrition of the people. for instance, the annual production of manioc, red onion, big onion and green chillies are 184,260, 35,480, 16,920 and 50,720 mt, respectively (census and statistics, 2019). while certain information on the production of these crops is available (census and statistics, 2019), details on their post-harvest losses are minimum. possessing these information would be of great importance for taking appropriate remedial measures to minimise the said losses. therefore, this study was conducted in selected areas in trincomalee district to determine the nature of crop farming and post-harvest losses of the crops grown in those areas. 2. materials and methods nilaveli and mahadiwulwewa, two areas in trincomalee district having different farming approaches were selected for this survey. while nilaweli is modernised mahadiwulwewa still follows traditional farming. from each location, 35 farmer families were selected and their information was collected using a questionnaire. the information collected included age of the farmers engaged in crop cultivation, types of crops cultivated and their amount, land use for crop cultivation, involvement in selected agricultural practices, storage of harvested yield and their losses. 2.1 statistical analyses data collected from nilaveli and mahadiwulwewa in respective of age distribution of farmers, percentage farmers cultivated crops, average land extent of cultivated crops in nilaveli, use of machines for post-harvest practices nilaveli and storage losses of different agricultural commodities were analysed as percentage with respective to the stored quantity. 3. results and discussion the majority of farmers engaged in farming was between 50-59 years of age in both mahadiulwewa and nilaveli areas (figure 1). among those older than 59 years engaged in crop cultivation, more people were from mahadiwulwewa than nilaveli. it is also recorded that in mahadiwulwewa, people engaged in cultivation even in older ages. this would have been a consequence of continuation of traditional farming in which they were engaged for generations in mahadivulwewa whereas urbanisation in nilaveli would have altered involvement in farming among younger people. however, the exact reason needs to be investigated in a future study. in general, the majority of famers in the dry zone belongs to the age group 41-50 years (sangakkara and frossard, 2014). in comparison, the majority of farmers as found in the current study belongs to 50-59 year age group in both nilaveli and mahadiwlwewa. dissanayaka and wijayaratne/ journal of tropical forestry and environment vol. 10 no. 02 (2020) 51-58 53 in terms of the crops grown, the rural-based mahadiwulwewa had mainly paddy cultivation. in contrast, nilaveli had a variety of crops grown. these include onion (allium cepa), egg plant (solanum melongena), cassava (manihot esculenta), long bean (vigna unguiculata), papaya (carica papaya), chilli (capsicum annuum), winged bean (psophocarpus tetragonolobus), tobacco (nicotiana tabacum) (figure 2). urbanisation in nilaveli compared to mahadiwulwewa may have opened avenues for the commercialisation of crop cultivation beyond traditional paddy cultivation. on the whole, paddy farming leads the crop cultivation and occupy 73% of the total cultivated area in nilaveli. mahadiwulwewa has more emphasis on paddy among the economically valuable crops than other crops. the study reveals a wide variation of the rice yield between nilaveli and mahadiwulwewa. the average yield of paddy was 1500 kg/ac for mahadiulwewa and lower than nilaveli which had 1,718 kg/ac. the reasons for the variation in paddy yield between nilaveli and mahadiulwewa seem to be due to the differences in the use of organic and inorganic fertilizer and agro-chemicals, availability and management of irrigation facilities, soil properties, and knowledge of farmers on agronomic practices. the productivity of other crops grown in nilaveli varied as 4,821 kg/ac for onion, 3,250 kg/ac for egg plant, 300 kg/ac for papaya and 1,500 kg/ac for chilli. despite the mechanisation of agriculture, still manual harvesting is practiced for majority of crops. the mechanical harvesting is used only for paddy (figure 4). in paddy cultivation the farmers in mahadiulwewa used machines for harvesting and threshing. they mostly used combine harvesters and combine threshers. mahadiulwewa have lager number of paddy farmers than the nilaveli. therefore it would be a reason for using more mechanical force for harvesting and threshing of paddy compared to nilaveli. but in drying of paddy, the machines were not used. instead, sun drying is practiced in both nilaveli and mahadiulwewa. also farmers in nilaveli and mahadiulwewa were not awareness on the recently-developed paddy dryers and new drying techniques (shyamali et al., 2009; bandara et al., 2014; dissanayake et al., 2016). furthermore, machineries were not used during harvesting or post-harvest operations of other crops in nilaveli and mahadiwulwewa. in both nilaveli and mahadiwulwewa, paddy is stored for 3-6 months for consumption and to prepare seed paddy for the next cropping season. in general, paddy is stored in jute sacks or gunny bags in both areas. jute sacks have nearly 30-50 kg whereas gunny bags have 45-60 kg. the preferred practice is these bags are stacked on wooden pallets inside small rooms near houses. normally they use 8-12 layers of bags for one stack. in contrast to the above practice of bag-storage of paddy, some farmers in nilaveli use traditional storage structures such as atuwa, bissa, passa kuruniya to store paddy. for this, mostly farmers use locally-available materials such as clay, wooden poles, palmyra leaves and bamboo to construct the storage structures. these structures are designed to protect grain or other harvested commodities from insects, mites, fungi, rodents and birds. these records agree with previous finding (adhikarinayake, 2005). the sri lankan farmers who store cereals don’t have adequate awareness on small-scale storage structures that accompany minimal post-harvest losses (adhikarinayake, 2005; adhikarinayake et al., 2006). there were important findings on the storage practices adopted for other crops as well. onion bulbs were left for 3-4 days in the field following harvesting to allow drying of leaves. following this, the onion bulbs were prepared as bunches by using dried leaves. one onion bunch nearly consisted of 50-75 onions bulbs. the bunches were hung as piles inside a small room which is situated near house. farmers store these bunches for 3-6 months. in tobacco, 10-15 leaves were piled on each other and these piles were hung on a cable inside the small hut having natural ventilation for 2-3 weeks. well-dried leaves were stored inside the storage. 54 the post-harvest losses for paddy were higher in nilaveli (2% of the harvested yield) than mahadiwulwewa (1.5%) (figure 5). of this, 70% losses occur due to insects. rhyzopertha dominica (f.) (coleoptera: bostrychiade), sitophilus oryzae (l.) (coleoptera: curculionidae), sitotroga cerealella (olivier) (lepidoptera: gelichiiade) are most common storage pests in both nilaveli and mahadiulwewa. other than that, damage of rodents is a major problem in mahadiulwewa during paddy storage. onion showed 3% losses during storage due to fungal attack. tobacco had 2% damage from cigarette beetle lasioderma serricorne (f.) (coleoptera: anobiidae). figure 1. age distribution of farmers in nilaveli and mahadiwulwawa areas. figure 2. percentage farmers cultivate crops in nilaveli and mahadiulwewa. 10 20 30 40 50 60 70 80 90 100 n u m b e r o f fa rm e s (% ) nilaweli mahadiulwewa a b c c c cc d c d 0% 5% 10% 15% 20% 25% 30% 35% 20-29 30-39 40-49 50-59 60-69 70-79 80-89 n u m b e r o f f a rm e s (% ) age (years) nilaweli mahadiulwewa dissanayaka and wijayaratne/ journal of tropical forestry and environment vol. 10 no. 02 (2020) 51-58 55 figure 3. land extent of cultivated crops in nilaveli. figure 4. use of the machines for post-harvest practices nilaveli. 73% 17% 1% 3% 0% 1% 1% 1% 3% paddy onion egg plant cassava long bean papaya chilli wing bean tobbaco 0% 20% 40% 60% 80% 100% paddy onion egg plant cassava long bean papaya chilli wing bean tobbaco manual machine & manual machine 56 figure 5. storage losses of different agricultural commodities. in the small holding sector out of total extent of agricultural land, paddy contributes to 33.5%. in trincomalee, land area cultivated with paddy is 71% of agricultural land (department of census and statistics, 2013/2014). in nilaveli there are 73% for paddy cultivation and 27% for other crops. also mahadiwulwewa has 100% paddy cultivation (figure 3). thus there is significant variation in the land use pattern based on the geographical area. there are several economically-valuable crops in nilaveli area but paddy is the only economically valuable crop in mahadiwulwewa area. red onion is a major crop among the farm families in nilaveli area. on account of all the crop grown in these two areas, the highest annual yield is obtained from onion cultivation. the production of cereals is seasonal. therefore, the surplus production aside the consumption is stored to meet the consumer demand during off-seasons (proctor 1994; dowell and dowell, 2017). 4. conclusion paddy is the major economically-valuable crop in mahadiwulwewa. in nilaveli, farmers cultivate several upland crops other than paddy. the farmers in mahadiwulwewa engage in cultivation at their older years. the farmers in both areas use jute sack and gunny bag to store paddy and they use different structures to store onion and tobacco. stored-product insects, rodents are the main sources for yield losses during storage. acknowledgement the authors thank a.m.p. sammani, g.r.p.m. samaranayaka, b.m.l.m. karunarathna, p.m.n. chandima, h.m.i.m. wijerathna, s.g.s. harshana, d.k.a. heshani, j.k.a.d. kalhari for assisting data collection. references adhikarinayake, t.b., 2005. methodical design process to improve income of paddy farmers in sri lanka. phd thesis wageningen university. 9-10 0 0.5 1 1.5 2 2.5 3 3.5 paddy onion tobacco p o st h a rv e st l o ss e s (% ) crops nilaweli mahadiulwewa dissanayaka and wijayaratne/ journal of tropical forestry and environment vol. 10 no. 02 (2020) 51-58 57 adhikarinayake, t.b., palipane, k.b. and muller, j., 2006. quality change and mass loss of paddy during airtight storage in a ferro-cement bin in sri lanka. journal of stored products research, 42:377390. african post harvest losses information system (aphlis), 2011. http://www.aphlis. net. accessed 31 august 2020. bandara, b.d.m.p., gunawardana, c.r., senanayake, d.p. and thilakarathne, b.m.k.s. 2014. design and development of a small scale paddy dryer. international symposium on agriculture and environment 2014, ruhuna, sri lanka, pp 347-349. baributsa, d. 2012. bagging bugs reduces post-harvest losses. the 10th fumigants & pheromones conference, indianapolis, indiana, usa. basic population information on trincomalee district, 2007. department of census and statistics. bio diversity clearing house mechanism, 2016-2017. agro ecological regions. http://lk.chm-cbd.net/? page_id=176. accessed 14 october 2020. department of census and statistics, 2013/2014. http://www.statistics.gov.lk/economic/final_report_ agri.pdf. accessed 15 october 2020. department of census and statistics, 2019. http://www.statistics.gov.lk/agriculture/staticalinformation /paddystatistics. accessed 20 november 2020. dissanayake, m., bandara, s., rathnayake, h.m.a.p., thilakaratne, b.m.k.s. and wijerathne, d.b.t. 2016. development of mobile dryer for freshly harvested paddy. procedia food science, 6:78-81. donahaye, e.j., navarro, s., ziv, a., blauschild, y. and weerasinghe, d., 1991. storage of paddy in hermetically sealed plastic liners in sri lanka. tropical science, 31:109-121. dowell, f.e. and dowell, c.n. 2017. reducing grain storage losses in developing countries. quality assurance and safety of crops and foods, 9:93-100. hagstrum, d.w. and subramanyam, b. 2006. fundamentals of stored-product entomology. aacc international, st paul. hill, d.s. 1990. pests of stored products and their control. belhaven press, london. khare, b.p., 2015. stored grain pests and their management. kalyani publishers, new delhi, kumar, d. and kalita, p. 2017. reducing postharvest losses during storage of grain crops to strengthen food security in developing countries. foods, 6:8. kumari, j.m.p, wijayaratne, l.k.w., jayawardena, n.w.i.a. and egodawatta, w.c.p. 2020. quantitative and qualitative losses in paddy, maize and greengram stored under household conditions in anuradhapura district of sri lanka. sri lankan journal of agriculture and ecosystems, 2:99-106. mvumi, b.m. and stathers, t.e. 2014. food security challenges in sub-saharan africa: the potential contribution of postharvest skills, science and technology in closing the gap. in: proceedings of the 11th international working conference on stored product protection, 24-28 november 2014 chiang mai, thailand. 32-43. palipane, k.b., 2001. current storage practices and quality improvement of stored grains. in: proceedings of the seminar organized by sri lanka association for the advancement of science (slaas) in association with university of kelaniya. sri lanka and food and agriculture organization, colombo, sri lanka, 13th july, 2001, pp 17-30. proctor d.l. 1994. grain storage techniques-evaluation and trends in developing countries. food and agriculture organization, rome, italy. sangakkara, r. and frossard, e. 2014. home gardens and dioscorea species a case study from the climatic zones of sri lanka. journal of agriculture and rural development in the tropics and subtropics, 115:55-65. 58 shyamali, a., jayaweera, h. and ariyaratne, t., 2009. thin-layer drying of some sri lankan paddy varieties under low humid conditions. in: proceedings of the technical sessions institute of physics, 25:36-44. sinha, r.n. and watters, f.l., 1985. insect pests of flour mills, grain elevators, and feed mills and their control. agriculture canada publication, ottawa. waisundara, v.y. 2020. traditional functional food of sri lanka and their health significance. in: prakash, j., waisundara, v. and prakash, v. (eds.), nutritional and health aspects of food in south asian countries, academic press, pp. 143-158. wijayaratne, l.k.w, fernando, m.d. and palipane, k.b. 2009. control of insect pests under ware-house conditions using smoke generated from partial combustion of rice (paddy) husk. journal of the national science foundation of sri lanka, 37:125-134. wijayaratne, l.k.w., arthur, f.h. and whyard, s., 2018. methoprene and control of stored-product insects. journal of stored products research, 76:161-169. microsoft word 5 okpo unanaonwi & olufemi /journal of tropical forestry and environment vol. 3, no. 01 (2013) 40-44 37 effect of tree height and girth on gum yield of acacia senegal l. in savanna woodland of nigeria o.e. unanaonwi 1* and s.o. bada 2 1 department of biological sciences, federal university, otueke, bayelsa state, nigeria 2 department of forest resources management, university of ibadan, nigeria date received: 29-11-2012 date accepted: 28-03-2013 abstract parameters influencing gum yield such as tapping techniques and soil mineral elements had earlier been investigated while there is dearth of information on effect of morphological characteristics on gum yield. this study investigated effects of height and girth on yield of acacia senegal l. in the natural forests. three heights and girth classes were purposely selected. trees which heights and girth fell within those classes were selected randomly and tapped at constant height classes with varying girth classes. exudates were collected, weighed and recorded according to height and girth class respectively. descriptive and anova results showed that when total tree height was lower than 2.0 m, gum yield increased as tree girth goes higher from 35 54cm (163.6 209.7g). tree girth significantly affected gum yield (p≤0.05) and trees which total heights were lower than 2.0m (maximum of 1.95m) and girth higher than 54cm (maximum of 65cm) produced the highest mean gum yield. silvicultural practices that could bring about increase in girth such as early pruning and re-spacing which is applicable to plantation trees could also be carried out on the natural forest trees to increase gum yield. key words: savanna woodland, acacia senegal, gum yield. 1. introduction acacia senegal l. (willdenow) is a multipurpose sub-saharan tree species from which gum arabic is collected. the term gum arabic is used with varying definitions by different groups of people. it acquired its name because the early traders were arabs (maydell, 1990). in the context of its use as a food additive, the most current international specification published by fao (1990), defines gum arabic as the “dried exudation obtained from the stems and branches of acacia senegal l. (willdenow) or closely related species. fao (2004) identified gum arabic as a potential commodity in world trade while it has been the main stay of the sudanese economy for over 400 years (lawal, 1998). thompkins (2007) reported that in the days of the egyptian pharaohs, gum arabic was essential for mummification, and since biblical times, it has been used to maintain the integrity of paints. milbak (2007) described it as a natural emulsifier. this means that it can keep together substances which normally would not mix well. pharmaceutical companies use it to keep medicine from separating into their different ingredients, and a dab of gum arabic makes newspaper ink more cohesive and permanent. *correspondence: okpoesio2002@yahoo.com tel: +23 40706 9248319 issn 2235-9370 print / issn 2235-9362 online ©2013 university of sri jayewardenepura unanaonwi & olufemi /journal of tropical forestry and environment vol. 3, no. 01 (2013) 40-44 38 in recent time, gum arabic has been brought into prominence in international diplomacy. it is being used as a tool by sudan against sanctions by the united states. according to report in a press conference held at the washington press club on 30th may 2007, john ukec lueth, sudan’s ambassador to the united states threatened to stop exportation of gum arabic from his country if sanctions were imposed. america’s coca-cola derives 80% of its emulsifier from gum imported from the sudan. gum arabic keeps sugar suspended so that it would not precipitate to the bottom of the drink. many uses of gum arabic in folk medicines have been reported by wyk and erik (2005), fao (1992), naude (1994) and nas (1981). gum export the export of gum arabic to europe started in nigeria in 1914 (fda, 2001) before oil exploration, but unfortunately it has been abandoned for oil export. the world demand for gum arabic has increased tremendously over the years. however, its market price has been declining since 1991 when it was sold at $6,000 per ton for the highest grade i gum and by 1994, the same grade was sold for $4,000 (fda, 2002). the nigerian gums are principally exported to europe, japan, usa, hong kong and india. in 1995, total export to the european union (eu) was 3,683 metric tons valued at $5,960,000, while india imported a total of 2,542 metric at $1,150,026 (lawal, 1998). thus, the eu is the major importer of nigerian gums, followed by india and then the usa. exports of gum arabic from nigeria have declined due to declining prices in international markets. gums for export are generally graded into two; grade 1 and grade 2. grade 1 gum are those collected purely from acacia senegal, while grade 2 gum are those collected from acacia seyal and other acacia species. grade 1 gum is the higher quality and more preferred but farmers and buying agents do adulterate the grade 1 gum with other gum which is not from acacia senegal. in reality with the present economy, the federal government of nigeria on the 4 th of september, 2009 announced a re-direction of attention to the production of gum arabic, describing it as a lost cash crop. it therefore calls for groups and private participation in the production of which plantation establishment is the only option if the over-all national production must be raised. however, most of nigeria’s gum comes from the wild (fda, 2002) and unanaonwi (2008) reported that gum yield on a per tree basis was higher in the natural forest than in the plantation. the question then arises as to what silvicultural interventions could be employed to improve yield in the natural forest which is the current main source of nigeria’s gum. the aim of this study is to investigate the effect of tree height and girth on gum yield in the natural forest. 2. materials and methods 2.1 study site/area this study was conducted at gummi forest in zamfara state, nigeria. the area lies approximately between latitudes 11 0 30` and 25 0 15` north, and longitudes 40 0 50` and 70 0 15` east. the area experiences a long dry season from october to may and a short rainy season from june to september. these two seasons are attended with two major wind currents namely the cold easterly and the southwesterly wind. the dry season consists of a cold dry spell, usually referred to as hamatam, roughly from november to january, followed by a hot dry spell from february to april (singh and babaji 1989). rainfall in the area is erratic in nature, small in quantity with an annual mean of 724mm and of uneven distribution with a peak in august. the minimum and maximum temperatures fluctuate between 15 0 c and 41 0 c, january and april respectively (zadp, 1996). the state is located within the northern guinea savanna. the vegetation is characterized by tall grasses and shrubs; and short scattered trees of woodland. common tree species that could be found are acacia senegal, a. notilica, a. albida and khaya spp. among others. these species though natural, have gone through bush fires and exploitation over the years. unanaonwi & olufemi /journal of tropical forestry and environment vol. 3, no. 01 (2013) 40-44 39 multistage sampling method was used. this involved dividing the whole stands into blocks, and then subdividing each block into plots. one plot in each block was then studied, after adopting the random-withinblock sampling technique. the 900 ha forest was demarcated into 20 blocks each of 45ha. each block was then divided into plots 100x100m. these were finally sub divided into 50x50m sub-plots. nine sub-plots were randomly selected from a randomly selected plot within each block, for data collection. ten trees per sub-plot were purposely identified and measured according to height and girth class combination, with each sub-plot being assigned with a particular height and girth combination. tree heights were classed into three as follows: <2.0m; 2-2.5m; and >2.5m. the range of class was based on the general height of trees as pictured from the data. tree girth was equally classed into three of 35-44cm; 45-54cm; and >54cm. this range was based on the overall tree girth as represented in the primary measurements. the assigned tree and girth combinations were: 1. trees with height < 2.0m within girth class of 35-44cm. 2. trees with height < 2.0m within girth class of 45-54cm. 3. trees with height < 2.0m with girth class >54cm. 4. trees with height 2 –2.5m within girth class of 35-44cm. 5. trees with height 2 –2.5m within girth class of 45-54cm. 6. trees with height 2 –2.5m with girth >54cm 7. trees with height >2.5m within girth class of 35-44cm. 8. trees with height >2.5m within girth class of 45-54cm. 9. trees with height >2.5m with girth class >54cm. 2.2 data collection height, girth and yield measurements were carried out for three tapping seasons (three years). tree height was measured with graduated wooden pole and girth was measured with calibrated tape at 1.3m above ground (1ufro standard) and recorded according to their respective height/class combinations. trees were tapped using short cutlasses by slashing 20cm deep in a slanting position on one side of the stem as described by unanaonwi (2009). exudates were allowed to dry and were collected after four weeks and weighed accordingly. there were four further collections, weighing and recording fortnightly with the use of simple weighing scale. 2.3 data analysis data were analyzed using the spss. descriptive statistics was used while analysis of variance was conducted to test the hypotheses. 3. results and discussion influence of tree physical characteristics such as heights and girths have been widely used in yield estimates in forestry where timber yield in volumes or logs of round wood draws heavily from information gotten from height and diameter at breast height (dbh). these parameters could also be used to estimate gum yield or yield of exudates of any tree species approximately. when the height was held at a constant of <2.0m with a maximum height of 1.95m, the yield increased along with increasing girth class, with maximum yield occurring at girth class >54cm (table 1). it means that if the girth continues to increase at a constant tree height of <2.0m, yield would be increasing. height in that case does not influence yield but tree girth does. increasing tree girth would unanaonwi & olufemi /journal of tropical forestry and environment vol. 3, no. 01 (2013) 40-44 40 therefore bring about increase gum production provided tree height is kept at about 1.95m below 2.0m. shorter trees tend to produce larger girth especially in the natural forest where trees do not undergo competition for light and space. the process of competition for light keeps tree growing taller with thinner bole and circumference. larger tree girth appears to favour the extension of the laticiferous layers where latex is stored. this layer would be small and thin in trees that are tall resulting into lower gum yield. table 1.result of mean gum yield with respect to height and girth combinations in natural forest height (m) girth (cm) yield (g) max min mean max min mean max min mean h < 2.0m; girth 35-44cm 1.5 1.0 1.25 44 35 41.3 204 101 163.6 h < 2.0m; girth 45-54cm 1.4 1.1 1.25 54 46 47.5 215 80 174.1 h< 2.0m; girth > 54cm 2.0 1.0 1.50 65 58 60.1 242 180 209.7 h 2 –2.5m; g 35-44cm 2.0 2.0 2.00 41 39 40.3 212 110 162.9 h 2 –2.5m; g 45-54cm 2.1 2.0 2.05 53 47 50.6 230 108 157.7 h 2 –2.5m; g >54cm h >2.5m; g35-44cm -_____ height held constant at lower than 2.0m, yield increases. height held constant at 2-2.5m, yield decreases with increasing girth. zero effect on yield as girth rises to greater than 54cm. when the height was increased to a constant of 2-2.5m within the first girth class, yield dropped by approximately 23%. on further increase of girth to the second class, yield dropped by 75%. on increasing girth further to >54cm, no tree was encountered within that girth class. since yield dropped within the first girth class on increasing the height, the 23% dropped in yield is attributed to the increased height from <2.0m to 2-2.5m. on the other hand, girth still had greater influence on yield as the first increase in girth class (45-54cm) leads to 75% increase in yield. the yield trend is on the reverse because of the impact of tree height but boosted by increasing girth. this further strengthened earlier hypothesis that yield would be on the increase at varying girth classes as long as tree height is brought to below 2.0m. the maximum height for that class was 2.08 while the maximum girth for the class was 53cm. it means that girth class beyond 54cm within height of 2-2.5m will yield no result in terms of gum yield. there were no trees found within height >2.5m and the highest tree was 2.08m. silvicultural manipulations for increased tree height would therefore not favour increased gum yield. tree girth significantly affected gum yield (p≤0.05) which confirmed the observation in table 1. silvicultural interventions that could result to increased tree girth such as crown pruning at younger age of tree would be appropriate for increased gum yield. plantation trees tend to grow taller than those in the natural forest due to competition factors which depend on planting distance. however, for large scale production of gum arabic, plantation establishment will be a good option if the planting distance is wide enough and epical pruning is carried out at the appropriate time to delay tree height while at the same time increase tree diameter. three girth classes were used in the study and it was therefore necessary to identify which of the girth class gave the highest yield figure. table 2 shows that trees with girth >54cm with <2.0m in height produced the highest amount of gum. no tree was encountered beyond the maximum height of 2.08m thus imposing a limit to the investigation. that is to say, the highest tree in the natural forest was 2.08m. table 2. results of duncan multiple range test for girth class and yield height and girth class (m; cm) yield (g)__ <2.0m; 35 – 44cm 163.225 a <2.0m; 45 – 54cm 176.800 a <2.0m; >54cm 209.700 b means with the same letter are not significantly different at α = 0.05 unanaonwi & olufemi /journal of tropical forestry and environment vol. 3, no. 01 (2013) 40-44 41 4. conclusion the study has shown that tree parameters such as girth and height have effects on the amount of gum yield of acacia senegal with larger tree girth giving higher amount of gum yield. the effects of height on yield were not significant (p≤0.05). apart from factors such as site quality, soil nutrient considerations, and tapping techniques, tree parameters such as height and girth also affect yield of exudating tree species, and should be considered when evaluating yield factors. keeping tree height to below 2.0m and allowing girth increment of about 60cm would bring the best yield result. farmers have better chance of increasing the amount of gum harvested if trees are manipulated such that it brings about increase in girth. prescribe burning and apical pruning during growth period would be an option in this respect, since it reduces profuse apical growth which brings about increase in tree height, for increase tree diameter. references fao, 1997. gum arabic, gum talha and other acaica gums. fao, rome. fao,1992. gum arabic (published in fao food and nutrition paper (110)pp. 735. in compendium of food additive specification fao food and nutrition paper 52 (joint fao/who expert committee on food additives. combined specifications from 1 st 37 th meetings (1956-1990). rome: food and agriculture organization. fao, 2004. exudates gum 2 in non-wood forest products for rural income and sustainable forestry. fao, rome. fda, (federal department of agriculture). (2001). field survey. baseline survey on gum arabic.2001 fda, 2002. baseline survey on gum arabic. 4-10. fda, 2009. field survey on national gum arabic hectarage pp235. gesrstanzang, j., sanders, e., 2007. impacts of bush’s sudan sanction doubted. los angeles times. may 30 th , 2007. lawal, a.m., 1998. export marketing of gum arabic. the nigerian experience. invited paper. tech. workshop on gum arabic. fda abuja, july 2002. maydell, h.v.,1990. trees and shrubs of the sahel: their characteristics and uses. typo-druk pub. gmb. germany, 41. milbak, d.,2007. beijing genocide at darfur-americans and their coca-cola. the washington post. http/www.usda .org. retrieved 11/8/2007. morton, j.f,. 1977. major medicinal plants. c.c. thomas, springfield ic. nas.,1981. acacia gum arabic. p.7. in food chemicals codex. third edition. 735. washington dc. national academy press. naude, a..1994. food additives 94. thickeners, the next generation. chemical marketing reporter (27 june), pp sr 16 singh, b.r., babaji, g.a., 1989. characteristics of the soils in bundaya districts. in : the soils of the university dry land form. nigerian journal of basic applied science. 3:7-16. thompkins, g.,2007.gum arabic; sudan’s miracle commodity. posted on june 20, 2007.{http/www. nprg.org.} retrieved 11/01/2010 unanaonwi, o.e., 2009 b . effect of tapping techniques on gum yield of acacia senegal l. journal of research in agriculture. vol.6 no.3 pp.33-38. unanaonwi, o.e., 2008 a. .gum yield of acacia senegal l. (willdenow) under plantation and natural forest in northern guinea savanna. production agriculture and technology pat 2008:4(2):102-113. www.patnsukjournal.com/current issue wyk, v., erick, b., 2005. food plants of the world. portland, oregon. timber press inc.78 zadp., (zamfara state agricultural development project.1996. handbook. ministry of agriculture, gusau. deepa and remadevi. /journal of tropical forestry and environment vol. 07, no. 01 (2017) 15-27 15 insecticidal factors from the seeds of erythrina indica lam against hyblaea puera, the most serious defoliator pest of teak deepa b.*1 and remadevi o. k. 2 1forest and wood protection division, institute of wood science & technology, karnataka, india 2environmental management & policy research institute, doresanipalya forest campus, bangalore, india date received: 10-03-2017 date accepted: 10-05-2017 abstract the organic solvent extracts from the seeds of erythrina indica were tested for their insecticidal action against hyblaea puera, the most important defoliator pest of teak. the larvicidal activity of the petroleum ether, chloroform, methanol, ethyl alcohol, ethyl acetate, acetone and water extracts from the seeds of e. indica on the 3rd instar larvae of h. puera showed 100% mortality even with least concentration (0.25%). the ovicidal activity was exhibited by chloroform and ethyl acetate extract. both the extracts exhibited highest egg hatch inhibition (56%) at highest concentration (2%). the least lc50 (1.15%) shows that ethyl acetate extract is better than chloroform extract (1.78). two compounds were isolated from the ethyl acetate extract of the seeds of erythrina indica by column chromatography. the compounds were identified using hplc, gc ms, and nmr. compound 1 was a mixture of linoleic acid and oleic acid. compound 2 was a mixture of linoleic acid and oleic acid ester with a glycerol unit attached to it. compounds 1 and 2 were biologically active and exhibited potent insecticidal activity against the 3rd instar larvae of h. puera. the result showed that compound 2 isolated from e. indica exhibited highest mortality (72%) at concentration (0.125%). at highest concentration (0.5%) highest mortality (92%) was exhibited by compound 2 which on comparison is on par with the neemark (azadirachtin) exhibiting highest mortality (100%). the study is complementary with earliar works and proves that the seeds of e. indica has immense potential to be utilized as botanical insecticide. keywords erythrina indica, seeds, fatty acids, triglycerides, insecticidal, hyblaea puera 1. introduction erythrina indica lam. syn. erythrina variegata var.orientalis (l.) merr. commonly known as tiger’s claw, indian coral tree and sunshine tree in india belongs to the family fabaceae. it is distributed along the sea coasts of india and also widely grown as shade tree in coffee plantations. it is also commonly available in sri lanka and malaysia. this is a moderate-sized tree, the trunk is armed with numerous prickles and bears bright cinnamon red flowers. flowering is from march to april. young leaves and tender shoots are eaten as vegetable (gunjatkar and vartak, 1982). the leaves are laxative, diuretic, antihelmintic, galactagogue and emmenagogue. they are applied externally for dispersing venereal buboes and for relieving pain in joints. the fresh leaves are used for the relief of ear ache and as anodyne *correspondence: deepa_balan2002@rediffmail.com tel: +919448803195 issn 2235-9370 print / issn 2235-9362 online ©2017 university of sri jayewardenepura 16 in tooth ache, the juice is also used to kill worms in sores (woi, 1952). the chemical constituent isolated is hypaphorine. this study was taken up with the objective of testing the insecticidal action of the organic solvent extracts of the seeds of e. indica on hyblaea puera, as the test insect. the study further involves isolation of insecticidal fatty acids and triglycerides from the ethyl acetate extract of the seeds of e. indica. 2. materials and methods collection of plant material and preparation of extracts the seeds of e. indica were collected from tumkur in karnataka, india. the seeds were shade dried. the dried seeds were powdered in a pulverizer. 100g of the plant material was dissolved in 250 ml of each of the solvent namely petroleum ether, chloroform, methanol, ethyl alcohol, ethyl acetate, acetone and water and kept for 48 hours in sealed round bottom flasks. after 48 hours, it was extracted in soxhlet apparatus until the eluting solvent turned colourless. the solvent was evaporated in a rotavapour and the dry crude extract obtained was weighed and stored in refrigerator. phytochemical analysis based on the bioassay, it was ascertained that the ethyl acetate extract of the seeds of e. indica were very effective as contact toxicants. hence, this extract were taken for detailed phytochemical analysis to find out the active ingredient responsible for the biological activity. analytical hplc the crude ethyl acetate extract of e. indica seed was subjected to reversedphase hplc to detect the compounds of interest. the column used was rp 18-reversed phase column with 25cm in length and 4.6mm in diameter. 1mg of the crude extract was injected into the column. two solvent systems were used namely, methanol-water (9:1) and acetonitrile-water (9:1) with flow rate of 1ml/min and column pressure up to 180 psi. uv detection of compounds of interest was done at 215nm. the solvent elution gradient is given in (table 1). table 1: solvent elution gradient of hplc time (min) concentration (a) % 0.01 100 5 80 10 60 15 40 20 20 25 0 35 0 40 100 column chromatography the crude ethyl acetate extract of the seeds of e. indica (10g) were purified further to obtain compounds of interest. a vertical glass column was packed with a suspension of silica gel (20g) (70-325 mesh) using hexane as solvent. the column was eluted with solvent gradually starting from 100% hexane followed by increasing order of ethyl acetate in hexane (0-100%) (table 2). deepa and remadevi. /journal of tropical forestry and environment vol. 07, no. 01 (2017) 15-27 17 table 2: solvent elution gradient for e. indica % of solvent eluted fraction volume of solvent used tlc mobile phase 100% hexane 1-16 800ml 20% etoac/ hexane 2% etoac/ hexane 17-42 1000ml 20% etoac/ hexane 5% etoac/ hexane 43-50 400ml 20% etoac/ hexane 8% etoac / hexane 51-60 500ml 20% etoac/ hexane 10% etoac / hexane 61-73 600ml 20% etoac/ hexane 15% etoac / hexane 74-94 800ml 20% etoac/ hexane 20% etoac / hexane 94-115 1000ml 20% etoac/ hexane 30% etoac / hexane 116-125 500ml 40%etoac/ hexane 50% etoac / hexane 126-134 500ml 60%etoac/ hexane 100% ethyl acetate 135-145 500ml 10%meoh/chcl3 etoac-ethyl acetate, meoh-methanol, chcl3chloroform structure elucidation of the active components the structural information of the isolated compounds were done using nuclear magnetic resonance (nmr) and mass spectroscopy (ms) techniques. nuclear magnetic resonance spectroscopy to elucidate the structure of the two isolated compounds, 1d nmr (1h nmr and 13c nmr) spectra were recorded on amx 400 mhz instrument using tms (tetramethylsilane) as internal standard. mass spectroscopy to determine the molecular weight, the sample was subjected to esims (electron spray ionization quadrupole mass spectrometry) in bruker esquire 3000 plus. source conditions were set as: voltage 4kv, nitrogen sheath (nebulizer) gas pressure 10psi, heated capillary temperature 250ºc, full scan 50m/z to 1050m/z, dry gas flow 5l/ min. preparation of the test concentrations from the crude extract a known amount of crude extract obtained from the above process was dissolved in respective solvent in 1:1 proportion and serially diluted with water to obtain the desired concentrations of 0.25%, 0.5%, 1%, 2% and 4%. one drop of emulsifier (0.005%) (tween 20, sigma chemical company) was added to the extract to ensure complete dispersion of the active ingredient. rearing of the test insect hyblaea puera cramer (lepidoptera: hyblaeidae) is the most important defoliator pest of teak in india. outbreaks occur almost every year in india, over extensive areas. during these outbreaks which occur 18 mainly during the early flushing period of teak, trees usually suffer total defoliation. the insect culture was maintained following a standard methodology (nair, et al., 1998). the pupae were brought to the laboratory and maintained in glass bottles covered with muslin cloth. the emerging adults were kept in cages overnight and then kept as pairs in separate glass bottles for mating. they were provided with 10 % honey solution for feeding. the adults usually mated on the first or second day of emergence and started laying eggs from the third night onwards. the eggs were laid on the cloth covering the bottles. the eggs were washed in 0.5% sodium hypochlorite solution for 10 minutes. after air-drying, the eggs were kept for emergence in glass bottles along with freshly collected tender teak leaves, sprayed with 0.5% sodium hypochlorite and air-dried. the larvae were kept in glass bottles along with fresh leaves and covered with muslin cloth. in each glass bottle 20 – 40 larvae were kept depending upon the instar. on moulting, larvae were changed to fresh bottles. on pupation, the pupae were removed and transferred to sterilized glass bottles. insect culture was maintained in the laboratory at 28ºc and 16l: 8d photoperiod and at 85% humidity. to maintain hygienic conditions the entire culture area was often sterilized with 70% alcohol. the glassware’s were sterilized with formalin after each wash. contact toxicity with crude extract to evaluate the contact toxicity effects of crude extracts of all the plants selected for study, two bioassays namely, larvicidal action and ovicidal action were conducted. larvicidal action with crude extract for bioassays to evaluate larvicidal action of crude extracts early 3rd instar larvae of h. puera of uniform age and weight range (9-13 mg) obtained from laboratory culture were used. contact toxicity was tested with 0.25%, 0.5%, 1%, 2% and 4% concentrations. five replications with 10 individuals each were used for each concentration. larvae were introduced into sterilized plastic petriplates. the test solutions were applied on larvae, as topical spray using a tlc (thin layer chromatography) sprayer. the petriplates were covered with the lid. in blank group the larvae were sprayed with water and in the control group the larvae were sprayed with respective solvent. tween 20 also served as a control. observations were made on the behaviour of the larvae and mortality was observed at 2hr, 4hr and 6hr. ovicidal action 12-hour-old eggs were carefully taken on a small piece of muslin cloth using fine camel hair brush. 5 replications with 5 eggs each were used for the experiment. the extract was prepared at a concentration of 2%, 1% and 0.5%. it was sprayed on the egg using a micropipette. the cloth with the eggs after complete drying was introduced into glass vials and covered with muslin cloth. treatment with water and respective solvents served as control. the eggs were observed for hatching after 48 hours. larvicidal action with the purified fractions the test compounds, two from the ethyl acetate extract of the seeds of e. indica were tested for their larvicidal action on the 3rd instar larvae of h. puera. the desired concentration of test solution 0.5%, 0.25%, 0.125%, 0.0625% of 2.5ml each was prepared. one drop of emulsifier (0.005%) (tween 20, sigma chemical company) was added with the extract to ensure complete dispersion of the active ingredient in water. the test compounds from e. indica were dissolved in cdcl3 (deuterochloroform). for comparison, bioassay was performed with commercially available neemark (azadirachtin 0.03%) was used. to evaluate the toxic effects of purified compounds, larvicidal action was studied on 3rd instar larvae of h. puera. contact toxicity was tested with 0.5%, 0.25%, 0.125%, 0.0625% concentration. five replications of 10 individuals each were used for each concentration. larvae were introduced into sterilized plastic petriplates. the test solutions were applied on the dorsum of the insects as topical deepa and remadevi. /journal of tropical forestry and environment vol. 07, no. 01 (2017) 15-27 19 application using a micropipette. each larva received 10 µl of the test solution. the petriplates were covered with the lid. in the blank group, the larvae were applied with water and the control group with respective solvent. tween 20 also served as a control. mortality was observed at 2hr, 4hr and 6hr after application. statistical analysis of the data percentage of larval mortality was calculated. the data was subjected to analysis of variance (anova) and the means separated using least significant difference (lsd). (lethal concentration) lc 50 were calculated using probit analysis according to calculations outlined in finney (1971). probit analysis was carried out using spss software program version 12 and anova was done with agres statistical package. 3. results and discussion larvicidal action the larvicidal activity of the seeds of e. indica against the 3rd instar larvae of h. puera did not vary among the different extracts. all the treatments were significantly different from the control. the larvae showed restless movement on spraying, had nervous tremors and convulsions and then became inactive and finally death ensued. the dead larvae became rigid. the extracts of e. indica had rapid action and the death occurred within two hours of spraying. all the extracts were highly effective causing 100% mortality even with least concentration (0.25%). the estabishment of the insecticidal property of the seeds of e. indica is supported by the study of chandrakantha (1988), wherein seed extract was reported to be toxic to the larvae and the pupae of the pulse beetle c. maculates. table 3: ovicidal activity of various extracts of e. indica sed cd (0.05) cd(0.01) treatment 0.62361 1.28707 1.75390 concentration 0.76376 1.57633 2.14808 t*c 1.08012 2.22927 3.03785 ovicidal action the ovicidal activity of the seed extracts of e. indica varied among the different extracts. all the treatments did not show any activity and were on par with control except chloroform and ethyl acetate extract. both the extracts exhibited highest egg hatch inhibition (56%) at highest concentration (2%) treatment concentration in % 2 1 0.5 ethyl acetate 56.00±43.35 (48.45) 52.00±22.80 (46.15) 36.00±35.77 (36.87) chloroform 56.00±38.47 (48.45) 32.00±36.33 (34.45) 32.00±22.80 (34.45) control 0.00(0.00) 0.00(0.00) 0.00(0.00) 20 (table 3). the least lc50 (1.15%) shows that ethyl acetate extract is better than chloroform extract (1.78) (table 4). the study is supported by the finding of ghatak and bhusan (1995 a and b) that the seeds of e. indica produced 100% hatch inhibition to eggs of corcyra cephalonica and s. oblique. mean ± sd represents mean percentage mortality of 5 replicates with 5 individuals each.means followed by the same alphabet does not differ significantly at 5% level of significance. values within parentheses are angular transformed values. table 4: dose mortality response of h. puera on contact toxicity with e. indica. the chi-square value is less than 3.841 (df=1) is not significant (p>0.05). fruits of solanum indicum and e. indica were found to be effective in the laboratory against the aphid of rose, macrosiphum rosae (verma and srivastava, 1988). e. indica seed extract was reported to be toxic to the larvae and the pupae of the pulse beetle c. maculates and it showed antifeedant property to the adult beetles (chandrakantha, 1988). srinivasaperumal (1990) studied the effect of ether extract of e. indica seed against larvae of p. ricini. senthamizhselvan and muthukrishnan (1992) tested ether extract of e.indica seeds on the ergolis merione, porthesia scintillans and spodoptera exigua which caused larval mortality and the damage was decreased by 65% following the treatment with the highest concentration of each extract. ovicidal properties of the crude extracts of 8 indigenous plants namely a. indica, e. indica , piper nigrum, a. calamus, adenocalymna allicea, thevetia neriifolia , pachyrhizus erosus and annona squamosa were evaluated in the laboratory on eggs of corcyra cephalonica and spilosoma obliqua showed that e. indica possess ovicidal action (ghatak and bhusan, 1995a and b). phytochemical analysis based on the contact toxicity of the tested extracts, ethyl acetate extract of the seeds of e. indica was subjected to analytical hplc to detect the number of compounds present in the crude extract and thereafter to column chromatography for isolation of the active components. analytical hplc the ethyl acetate extract of the seeds of e. indica when incorporated for detection of compounds, through reversed phase hplc system on rp-18 column, maintained at a wave length of 215nm and flow rate of 1ml/ min using twin solvent system (water / methanol and water /acetonitrile) reveals a series of compounds eluting at different retention times. in the chromatographical estimation, since the concentration of sample is directly proportional to peak area, the detected compounds are explained as follows. the chromatogram (fig. 1) (table 5) of e. indica shows that the peaks eluted at a retention time (11.15 minutes) and (36.29 minutes) have maximum concentration (7.86%) and (9.89%). it is therefore concluded that there are two major components in the ethyl acetate extract of e. indica seeds. treatment lc 50 slope ± s.e intercept ± se chi-square ethyl acetate extract 1.15 0.84333 ± 0.59627 -0.05154 ± 0.14593 0.249 chloroform extract 1.78 1.04236 ± 0.60490 -0.26085 ± 0.14835 0.943 deepa and remadevi. /journal of tropical forestry and environment vol. 07, no. 01 (2017) 15-27 21 figure 1: ethyl acetate extract of seed of e. indica with water/ methanol as elutents figure: 2 ethyl acetate extract of seed of e. indica with water/ acetonitrile as elutents 22 table 5: retention time and peak area (%) of compounds from e. indica it was further confirmed when water/ acetonitrile was used as solvent system, which shows that the peaks eluted at a retention time (3.46 minutes) and (20.67 minutes) have maximum concentration (figure 2). column chromatography chromatographic column separation of the ethyl acetate fraction of the e. indica seeds resulted in the isolation of two compounds. both the compounds were eluted with 20% ethyl acetate/ hexane. retention time (min.) peak area (%) 3.1 0.1 3.3 0.13 3.5 0.05 6.8 0.37 8 0.21 8.2 0.34 8.5 0.35 8.9 0.59 9.3 0.2 9.6 0.92 10.4 1.66 10.5 0.87 11 1.17 11.7 7.86 12.6 2.86 13.1 0.74 13.5 0.52 13.8 30.02 14.5 0.62 15.8 5.07 16.1 4.4 16.4 8.6 17 8.9 17.6 5.1 21 0.5 21.3 1.11 21.5 0.91 22.3 1.32 22.6 0.81 27.17 2.55 28.8 0.92 36.2 9.89 40.4 2.69 44.6 2.86 deepa and remadevi. /journal of tropical forestry and environment vol. 07, no. 01 (2017) 15-27 23 compound 1(320mg, rf 0.76) was isolated as a pale yellow fluid. compound 2 (185mg, rf 0.55) was also isolated as yellow fluid. structure elucidation of the active principle the structure of the two compounds was elucidated by using nmr and mass spectroscopy. the 1h nmr and 13c nmr assignments were obtained by extensive use of 1d nmr techniques. compound 1: 1h nmr (400 mhz, cdcl3) 0.95 (m, 3h), 1.29 (bs, 14 h), 1.62 (m, 2h), 2.00 (m, 4h), 2.32 (m, 2h), 2.35 (m, 2h), 4.36 (m, 2h), 4.12 (m, 1h), 5.30 (m, 2h), 5.40 (m, 2h). 13c nmr (100 mhz, cdcl3) assignment is given in table 6. the spectral data were in agreement with the published data and confirmed that it is a mixture of free fatty acids (linoleic and oleic acid) (figure 3). table 6: 1 h and 13c-nmr data for compound 1 ho o figure 3: mixture of free fatty acid (linoleic and oleic acid) carbon  values in ppm hydrogen  values in ppm c-1 173.13 c-2 34.11 h-2 2.32 (2h, m) c-3 25.58 h-3 1.62 (2h, m) c-4 29.29 h-4 1.29 (2h, m) c-5 29.07 h-5 1.29 (2h, m) c-6 29.29 h-6 1.29 (2h,m) c-7 31.48 h-7 1.29 (2h,m) c-8 33.96 h-8 2.00 (2h,m) c-9 130.09 h-9 5.40 (1h,m) c-10 127.86 h-10 5.30 (1h,m) c-11 33.96 h-11 2.35 (2h,m) c-12 128.04 h-12 5.40 (1h,m) c-13 129.91 h-13 5.30 (1h,m) c-14 33.96 h-14 2.00 (2h,m) c-15 29.65 h-15 1.29 (2h,m) c-16 32.72 h-16 1.29 (2h,m) c-17 22.63 h-17 1.29 (2h,m) c-18 14.01 h-18 0.95 (3h,m) c-19 68.91 h-19 4.36 (2h,m) glycerol unit 71.20 4.12 (1h,m) glycerol unit 62.11 3.56 (2h,m) 24 compound 2: 1h nmr (400 mhz, cdcl3) 0.95 (m, 3h), 1.29 (bs, 14 h), 1.62 (m, 2h), 2.00 (m, 4h), 2.32 (m, 2h), 2.35 (m, 2h), 4.36 (m, 2h), 4.12 (m, 1h), 5.30 (m, 2h), 5.40 (m, 2h). 13c nmr (100 mhz, cdcl3) the assignment is given in table 7. the spectral data were in agreement with the published data and confirmed that it is triglycerides (r= glycerol unit connected to a mixture of linoleic and oleic acid ester) (figure 4). table 7: 1h and 13c nmr data for compound 2 carbon  values in ppm hydrogen  values in ppm c-1 179.85 c-2 34.07 h-2 2.32 (2h, m) c-3 25.63 h-3 1.62 (2h, m) c-4 29.08 h-4 1.29 (2h, m) c-5 29.08 h-5 1.29 (2h, m) c-6 29.33 h-6 1.29 (2h,m) c-7 31.53 h-7 1.29 (2h,m) c-8 34.07 h-8 2.00 (2h,m) c-9 130.19 h-9 5.40 (1h,m) c-10 127.91 h-10 5.30 (1h,m) c-11 37.40 h-11 2.35 (2h,m) c-12 128.08 h-12 5.40 (1h,m) c-13 129.71 h-13 5.30 (1h,m) c-14 33.49 h-14 2.00 (2h,m) c-15 29.68 h-15 1.29 (2h,m) c-16 32.76 h-16 1.29 (2h,m) c-17 23.63 h-17 1.29 (2h,m) c-18 14.01 h-18 0.95 (3h,m) glycerol unit 68.94 4.36 (2h,m) glycerol unit 71.20 4.12 (1h,m) glycerol unit 62.11 3.56 (2h,m) ro o figure 4: triglycerides (r= glycerol unit connected to a mixture of linoleic and oleic acid ester) contact toxicity with purified compounds the purified compounds from the crude extracts were of meager quantity. hence, the insecticidal potency of the purified compounds was tested only for larvicidal action by contact toxicity on the 3rd instar larvae of h. puera. the result showed that compound 2 isolated from e. indica exhibited highest mortality (72%) at concentration (0.125%). at highest concentration (0.5%) highest mortality (92%) was exhibited by compound 2. on comparison with neemark at higher concentrations compound 2 was on par with the neemark (azadirachtin) exhibiting highest mortality (100%) (table 8). deepa and remadevi. /journal of tropical forestry and environment vol. 07, no. 01 (2017) 15-27 25 table 8: percentage mortality of 3rd instar larvae of h. puera on contact toxicity with purified compounds. treatment concentration in % 0.5 0.25 0.125 0.0625 compound 1 82.00±24.89 (67.59)abc 44.00±33.62 (41.61)cd 44.00±15.17 (41.43)d 24.00±23.02 (27.48)ef compound 2 92.00±13.04 (74.79)ab 78.00±13.04 (63.13)bc 72.00±13.04 (58.66)c 44.00±5.48 (41.53)d azadirachtin 100.00±0.00 (80.90)a 100.00±0.00 (80.90)a 100.00±0.00 (80.90)a 100.00±0.00 (80.90)a blank 0.00 (9.10) 0.00 (9.10) 0.00 (9.10) 0.00 (9.10) control (respective solvent) 0.00 (9.10) 0.00 (9.10) 0.00 (9.10) 0.00 (9.10) tween 20 0.00 (9.10) 0.00 (9.10) 0.00 (9.10) 0.00 (9.10) sed cd (0.05) cd(0.01) treatment 0.45497 0.90545 1.20141 concentration 0.40694 0.80986 1.07458 e*c 0.90995 1.81089 2.40282 mean ± sd represents mean percentage mortality of 5 replicates with 10 individuals each. means followed by the same alphabet does not differ significantly at 5% level of significance. values with parenthesis are arcsine transformed values. the lc50 values are presented in table 9. the least lc50 (0.07%) exhibits that compound 2 is most effective, followed by compound 1 (0.18%). the result showed that the compounds 1 (mixture of linoleic and oleic acid) and 2 (triglycerides) isolated from the ethyl acetate extract of seed of e. indica are effective. 26 table 9: dose-mortality responses of 3rd instar larvae of h. puera on contact toxicity with purified compounds the chi-square value is less than 5.991 (df=2) is not significant (p>0.05). * the chi-square value is more than 5.991 (df=2) is significant (p<0.05). insecticidal activity of fatty acid constituents isolated from the seeds of d. palustris is reported by ramsewak et al. (2001) against a. aegyptii. insecticidal activity of oleic and linoleic acid against c. maculates showed ovicidal and oviposition deterrent activity. though the insecticidal activity of e. indica seed is reported, the study of larvicidal and ovicidal activity of linoleic acid and oleic acid isolated from the seeds of e. indica against h. puera is reported for the first time. deshpande et al.(1974) reported oleic and linoleic acid as insecticidal components from this plant, which were found to be toxic to the pulse beetle, callosobruchus chinensis. the triglycerides and fatty acids obtained from other plant sources have been shown to have pesticidal or insect growth regulatory activities, but to our knowledge this is the first report of biolological activity of triglycerides and fatty acids isolated from the seeds of erythrina indica showing insecticidal property against the larvae of hyblaea puera. 4. conclusions thus the study proves that the seeds of e. indica has immense potential to be utilized as botanical insecticide. at present, there is ever increasing demand for botanical based insecticide. further scientific validation, chemical profiling of the seeds of e. indica and extensive field trials is required to practically utilize the seeds of e. indica for developing marketable botanical insecticide. acknowledgement the first author acknowledges university grants commission, india for financial assistance. the authors are thankful to director, institute of wood science & technology for infrastructure and kerala forest research institute for helping in bioassay. references gunjatkar n, vartak vd. 1982. enumeration of wild legumes from pune district, maharashtra. journal of economic and taxonomic botany, 3:1-9 a dictionary of indian raw materials and industrial products. 1952. in woi (the wealth of india); publication and information directorate, csir, new delhi, india. iii (d-e): 30. treatment lc 50 fiducial limits slope ± s.e intercept ± se chisquare lower limit upper limit compound 1 0.18728 0.14158 0.25195 1.56842 ± 0.28808 1.14106 ± 0.2358 5.810 compound 2 0.06981 0.03934 0.09626 1.61496 ± 0.31399 1.86705 ± 0.28007 1.412 deepa and remadevi. /journal of tropical forestry and environment vol. 07, no. 01 (2017) 15-27 27 nair kss, varma rv, sudheendrakumar vv, mohandas k, mohamed ali mi. 1998. management of the teak defoliator (hyblaea puera) using nuclear polyhedrosis virus (npv). in kfri research report, 151: 8-9. chandrakantha j. 1988. effect of plant chemicals on food utilization in callosobruchus maculates. in abstract of iii national symp. on nutritional ecology of insects and environment, s.d. (pg) college, muzaffarnagar (up): 25. ghatak ss, bhusan tk. 1995a. evaluation on the ovicidal activity of some indigenous plant extracts on rice moth, corcyra cephalonica staint. (galleriidae: lepidoptera). environment and ecology, 13(2): 284-266. ghatak ss, bhusan tk. 1995b. evaluation on the ovicidal activity of some indigenous plant extracts on bihar hairy caterpillar, spilosoma oblique (wk.) (arctiidae: lepidoptera). environment and ecology, 13(2): 294-296. verma rr, srivastava ps. 1988. toxicity of some plant extracts to rose aphid macrosiphum rosae. progressive horticulture, 20(1-2): 181-182. srinivasaperumal s, muthukrishnan j, palavesam a. 1990. effect of plant chemicals on in vivo protease activity and food utilization in the armyworm pericallia ricini (fab.) (arctiidae: lepidoptera). proceedings of the indian national science academy part b, biological sciences, 56(5-6): 389395. senthamizhselvan m, muthukrishnan j. 1992. effect of plant chemicals on food consumption of three lepidopteran larvae. insect science and its application, 13(3), 429-434. ramsewak rs, nair mg, murugesan s, mattson wj, zasada j. 2001. insecticidal fatty acids and triglycerides from dirca palustris. j. agric. food. chem, 49: 5852-5856. deshpande r s, adhikary p s, tipris np. 1974. stored grain pest control agents from nigella sativa and pogostemon heyneamus. bull. grain. tech., 12: 232-234. issn 2235-9370 print / issn 2235-9362 online ©2017 university of sri jayewardenepura table 6: 1 h and 13c-nmr data for compound 1 compound 2: 1h nmr (400 mhz, cdcl3)  0.95 (m, 3h), 1.29 (bs, 14 h), 1.62 (m, 2h), 2.00 (m, 4h), 2.32 (m, 2h), 2.35 (m, 2h), 4.36 (m, 2h), 4.12 (m, 1h), 5.30 (m, 2h), 5.40 (m, 2h). 13c nmr (100 mhz, cdcl3) the assignment is given in table 7. the spec... table 7: 1h and 13c nmr data for compound 2 figure 4: triglycerides (r= glycerol unit connected to a mixture of linoleic and oleic acid ester) chapter five: discussion siriwardane et al. /journal of tropical forestry and environment vol. 5. no 01 (2015) 9-18 9 cloud based gis approach for monitoring environmental pollution in the coastal zone of kalutara, sri lanka m.s.p.m. sirirwardane 1* , m.a.d. samanmali 2 and r.n.p. rathnayake 3 1 gis solutions (pvt) ltd., 370, galle road, colombo 3, sri lanka 2 department of geography, faculty of arts, university of colombo, sri lanka 3 faculty of education, university of colombo, sri lanka date received: 31-12-2014 date accepted: 30-04-2015 abstract geographic information systems (gis) can be used as a powerful tool in many aspects of handling geospatial data. by considering the modern geospatial approaches, this research is focused on monitoring environmental pollution in the coastal zone of kalutara area, with the objective of identification of existing natural resources. green vegetation patches, water bodies and beech areas were detected using remote sensing techniques. a detailed gps field survey was conducted and identified minor environmental resources with various pollution incidents. this information was used to improve the available data sets. the types of pollution incidents were categorised according to the severity level by considering the relationship to each natural resource. maps were created and data was uploaded to the arcgis online cloud platform. web services were hosted using this cloud infrastructure. pollution incidents data layer has been given web based editing capabilities for field monitoring using gps enabled mobiles. field observations were conducted and locations of the pollution effects were uploaded into web maps from the field with related attributes. the hot spots were used to get better understanding and awareness of the environmental pollution. as the results, pollution incidents were identified and there was a significant effect to the minor environmental elements. the cloud infrastructure, helped to bring down the barriers of data sharing and the incident reporting mechanism became more convenient during the field observations. keywords: web gis, costal pollution, geospatial approaches, cloud gis 1. introduction geographic information systems (gis) can be recognised as a powerful tool in handling geospatial data for decision supporting activities. “decision support systems (dss) make use of a variety of information technologies and new technologies are playing an increasingly important role in decision support. one such field where new techniques have been developed is geographic information systems (keenan, 1997). gis provides a framework for gathering and organising spatial data and related information so that it can be displayed and analysed (esri knowledge base, 2014). with emerging development of information technology (it) and science, gis has been modernised. web gis, mobile gis and cloud gis techniques are become popular among the traditional gis users as well * correspondence: supunsiriwardane@gmail.com tel: +94 775255133 issn 2235-9370 print/issn 2235-9362 online © university of sri jayewardenepura 10 as non-gis communities. web gis becomes a cheap and easy way of disseminating geospatial data and processing tools. many organisations are interested to distribute maps and processing tools without time and location restriction to users. the ability to get information through internet made spatial data providers to explore the internet resources for disseminating spatial information (alesheikh et al., 2002). cloud computing is another emerging trend in the it world. it is defined as internet-based computing whereby information, it resources, and software applications are provided to computers and mobile devices on-demand (cloud computing, 2014). this clearly indicates the sharing of it resources off the premises of a particular client site. however, when explaining the relationship with gis and cloud computing, several aspects should be reviewed. following definition is explaining the core of it. cloud computing is rapidly emerging as a technology trend that almost every industry that provides or consumes software, hardware, and infrastructure can leverage. the technology and the architecture that cloud service and deployment models offer are key areas of research and development for geographic information system (gis) technology (kouyoumjian, 2010). according to these definitions the importance of the cloud techniques were highlighted with research and development perspectives. 2. methodology this research is focused on the cloud based gis approach for monitoring environmental pollution in the coastal zone of kalutara. the main objective of the study was to identify the pros and cons of the „pollution incident reporting mechanism‟ and monitoring it using gis technology. here a special focus has taken to coastal environment pollution. in order to obtain the main objective of this study the existing natural resources were identified using satellite images by visual interpretation and remote sensing techniques and minor environmental resources were identified types of pollution incident by conducting a detailed gps field survey. further hosted gis services were created on a cloud platform and reporting incidents from the field for monitoring activities and finally the incidents were analysed and the reporting mechanism was evaluated. three grama niladhari (gn) divisions were selected in the kalutara district secretariat (ds) divisions the study area. these gn divisions are bordering to the river “kalu” at the coastal zone of kalutara urban area. the river kalu is one of the four major rivers in sri lanka with a massive volume of water which are collected from the core rainfall of the wet zone. tropical forest areas like singharaja and western and south western part of the central hills are main sources for the river. it is fallen into the indian ocean at kalutara town and river mouth, lagoon and sand bars can be identified as special geomorphologic features which dominate in the study area. figure 1 indicates a relative location of the study area from an aerial view with the gn boundaries overlaid on a satellite image. there is another specialty of the area as it is highly interactive with natural and human activities. kalido beach is one of the special sites which have huge attractions of the local people and the foreigners. therefore, the interaction is higher than the other isolated coastal areas of the district. on the other hand the main city of kalutara is well inside the gn division called “kalutara south”. this area includes population concentrated areas as well as the crowded locations like railway station, main bus stand and also the kalutara bodhiya temple complex. therefore, a significant amount of population is moving through the area with a great level of interaction. this environment is always has a trend to be changed due to various activities of the river. the massive volume of water is always has an effect on changing the geomorphologic creations. for few siriwardane et al. /journal of tropical forestry and environment vol. 5. no 01 (2015) 9-18 11 decades the river mouth has been shifted up and down, because of the energy and materials coming from the giant water body. with these factors, there is a huge discussion regarding the costal pollution and the protection of the natural beauty. currently, the pollution and resource monitoring mechanism are not very clear for the entire area. figure1: the aerial view of the study area. the methodology can be explained using several distinguish stages. the beginning of the process the boundaries of the study area were defined using the administrative boundaries data from the survey department of sri lanka. these boundaries were overlaid on the satellite images with proper coordinate system. the detection of available natural resources in the study area was derived through high resolution satellite images of geoeye and web imagery services form esri (environment systems research institute). the row images were enhanced with several image processing techniques. then visually interpreted with understanding of coastal geomorphology and several features were clearly identified during the process. green vegetation patches were carefully digitized as they are smoothly distributed along the coastal zone. water bodies and sandy beaches were mapped using supervised image classification techniques as they were spreading unevenly within the study area. in fact, this level is not perfectly fit into the precise detection of all the resources due to the limitations of image resolutions. therefore, a field survey was conducted using the facility of gps (global positioning systems) technology. the minor resources like sand dunes, mangrove filled river banks, seasonal salt marshes and thin stream networks were identified. at the same time the types of pollution incidents were observed. this was done for building up a categorised data model for the pollution incidents. this data model was important for the geo-database which consisted with all the datasets available in the study area. the resources datasets were improved by the field observation results and comprehensive dataset was created. figure 2 indicates the methodology in detail. using the created datasets a geodatabase was created using arcgis and geodatabase domains and subtypes were assigned. using the developed data, map documents were created with specific symbol formats. these maps were published into a cloud 12 platform called arcgis online and given the editing capabilities to the pollution incidents layer. the aim was to enabling the mobile based data editing from the field. figure 2: the methodology used for the present study. after uploading the data sets the pollution incident layer was hosted as a feature service which supports attachments such as photographs. using arcgis online, a web map was created with the natural resources layer which mainly contained vegetation patches as well as pollution incidents. using the web app builder in the cloud platform, a new app was created for pollution incident monitoring. this app was accessible for particular login mobile device from the mobile device. simultaneously an operational dashboard was created to get the incidents and this operational view has the ability to display the data with all the updates from the field. this architecture was tested from the field and incidents were uploaded to the system. the data was then processed and analysed hot spots for better understanding about the bulk of incident concentrations. figure 3 indicates the system architecture. figure 3: the system architecture with the components. siriwardane et al. /journal of tropical forestry and environment vol. 5. no 01 (2015) 9-18 13 using the cloud infrastructure, the mobile app was able to send the information collected from the field. this was done for 3 days and 44 incidents were reported. figure 4 indicates the appearance of the mobile app with the collected incidents. when adding a new incident as a point feature, there is an option to include attributes as well as attachments. when the observations were taking place, a severity level was also mentioned as an attribute, this level was created during the data model creation, with the knowledge achieved at the first field visit. some expertise knowledge as well as research experience are used for this process and there are 1-5 values which increases the severity with the higher number. during the observations, by considering the human sensors, a value was assigned with the discussion of three participants of the field visit. but there is a difference of ideas and if the members are changed the values can be also changed. that act as limitation of this severity indicator and there is no chemical testing or modelling of the phenomena to get a precise measurement of the pollution level from the field. this stage is limited to observed incidents and some sort of severity level indication of the problem using only the human sensors. figure 4: the interface of the data collection app, list of layers and attachments. using the collected incident locations, a point density analysis was done with considering the severity level. using arcgis software, the kernel density tool was used and as the population (weighted) field, the severity field was given. the algorithm used to determine the default search radius, also known as the bandwidth, is as follows: calculate the mean centre of the input points. if a population field other than none was selected, this, and all the following calculations, will be weighed by the values in that field. calculate the distance from the (weighted) mean centre for all points. calculate the (weighted) median of these distances, dm. calculate the (weighted) standard distance, sd. 14 apply the formula in equation 1 to calculate the bandwidth:   0.2 ndm 2ln 1 sd,min0.9raduis search            (1) where: sd = standard distance dm= median distance n = number of points if no population field is used, or if a population field is supplied, n is the sum of the population field values. the min part of the equation means that whichever of the two options that results in a smaller value will be used. this approach to calculating a default radius generally avoids the "ring around the points" phenomenon that often occurred with sparse datasets (arcgis resource center, 2014). 3. results as the results, pollution incidents were identified throughout the study area and there was a significant effect to the minor environmental elements. most of the cases are distributed nearby locations to the river and solid waste deposits were concentrated around the lagoon area. in fact these waste materials may be having different levels of effects on to this environment. chemical effect cannot be measurably identified from the field but visual pollution as well as the level of stink has an indirect indication of the live measurements by human sensors. these live observations were reported to the dashboard for further interpretation of the incidents. according to the reported incidents the data was categorized and important information was derived. from the field observations, 44 locations were uploaded to the system and highest incident were related to the solid waste depositions (table 1). table 1: reported pollution incidents and descriptive statistics. further reviewing the data, figure 4 indicates the comparison of all the incidents which have been reported in the study area during the observed period. solid waste depositions, damaging costal vegetation and water related pollution incidents cover more than 80% of the incidents. pollution type no of incidents percentage damaged plants 12.00 27 effects to animal habitats 3.00 7 other 1.00 2 sand excavation 4.00 9 solid waste 16.00 36 water pollution 8.00 18 sum 44.00 100 average 7.33 17 max 16.00 36 min 1.00 2 siriwardane et al. /journal of tropical forestry and environment vol. 5. no 01 (2015) 9-18 15 figure 5: comparison of the incidents. the kernel density analysis has given important information regarding the overall pollution effect. especially, several areas around the lagoon were reported clustered incidents. as the severity was considered and weighed, the south eastern part of the study area reflected a hotspot for pollution effects. figure 6 indicate the density map for reported pollution incidents. figure 6: the density map for reported pollution incidents. 0 5 10 15 20 25 30 35 40 damaged plants effects to animal habitats other sand excavation solid waste water pollution percentage 16 4. discussion when analysing the reported incidents a fact was found that the average level of the incidents was 7.33 during the observed period. however, for the solid waste deposits are four time larger than the average value and clearly indicates the effect from the waste (table 2). there was more concentration around the lagoon area and it can be interpreted as an impact forms the river and pollutants which were fallen from the distance areas and deposited at the lagoon. but these wastes may be coming from the nearby areas or from the visitors to the site. table 2: the deviation of the reported pollution incidents. as the initial level of the observations the incidents are only made for a 3 day period but this is currently developing into a periodic data collection for more advanced time series analysis. there was a hotspot identified in the south eastern part of the study area. it indicates the human interactions and nearby settlements have more impact on these incidents. however, there is another hotspot at the river mouth and most of the cases due to the depositions of the river. but there were a solid waste deposition which indirectly indicates the pollutants which have been dropped into the river. figure 7 was taken during the field survey and it shows the artificial plastic water bottles collected at the river mouth area. figure 7: solid waste depositions at the river mouth. when reviewing the technical infrastructure, the cloud platform which is used to facilitate the data collection, has a significant level of efficiency, but when the signal strength become weak in the mobile devices, the app‟s performance was getting low. especially the base maps (the background maps) were delayed to draw. the other disadvantage in this type of system is the cost of the services based on the amount of data. as a user has to pay for the services and facilities in the cloud, the large amount of data will increase the cost. this research has a mechanism of incident reporting using a cloud based it facilities and a way of monitoring the incidents using geographical perspective. this pollution type percentage median deviation damaged plants 27 7.33 19.67 effects to animal habitats 7 7.33 -0.33 other 2 7.33 -5.33 sand excavation 9 7.33 1.67 solid waste 36 7.33 28.67 water pollution 18 7.33 10.67 siriwardane et al. /journal of tropical forestry and environment vol. 5. no 01 (2015) 9-18 17 type of approach has an impact for many organisations who are involved in environmental protection. this can be used as a guideline for testing practical applications for those organisations. there is an opportunity of integrating participatory gis as well as community engagement. the importance of the study is not only identifying the current pollution effects, but also the development of next generation applications of gis which engage responsible organisation‟s field staff, experts, decision makers, and the community. 5. conclusion the pollution monitoring is one of the important aspects for the sustainability of environment. there are many organisations who involves in these activities and this type of infrastructure will be important in many ways. in this scenario gis based cloud infrastructure, helped to bring down the barriers of data sharing in a significant way. therefore, the incident reporting mechanism became more convenient during the field observations. the dashboard represents an efficient way of identifying pollution as well as a decision supporting procedure for preventing coastal environmental pollution. the advantages of using cloud infrastructure can be identified as reduction of hardware and software limitations and bring down the barriers of data sharing. but there are disadvantages such as amount of data uploads will gain cost for the users. references amaeze, n.h., philominathanegonmwan, r.i., jolaoso, a.f. and otitoloju, a.a. 2012. coastal environmental pollution and fish species diversity in lagos lagoon, nigeria. http://webcache.googleusercontent.com/search?q=cache:k9g_bg_isysj:www.academicpub. [accessed 20 nov 2014] alesheikh, a.a., helali, h. and behroz, h.a. web gis: technologies and its applications dept. of geodesy and geomatics eng., k.n.toosi university of technology http://www.isprs.org/proceedings/xxxiv/part4/pdfpapers/422.pdf [accessed 20 nov 2014] arcgis resource center. 2015. http://resources.arcgis.com/en/help/main/ 10.2/index.html# howkernel densityworks [accessed 22 oct 2014] atheull, a.n., din, n., longonje, s.n., koedam, n. and guebas, f.g. 2009. commercial activities and subsistence utilization of mangrove forests around the wouri estuary and the douala-edea reserve.http://www.ulb.ac.be/sciences/biocomplexity [accessed 29 nov 2014] bhat, m.a., ahmad, b. and shah, r.m. 2011. cloud computing: a solution to geographical information systems (gis).http://www.enggjournals.com/ijcse/doc/ijcse11-03-02006.pdf. [accessed 23 nov 2014] choi, j.y., engel, b.a. and farnsworth, r.l. web-based gis and spatial decision support system for watershed management. cloud computing. 2014. http://www.cloudcomputingdefined.com [accessed 10 oct 2014] esri knowledge base. 2015. http://support.esri.com [accessed 16 oct 2014] fao. 1998. status of urban trees and forests in the region regional overview of urban forest resources. http://www.fao.org/docrep/003/x1577e/x1577e06.htm#topofpage/ [accessed 29 nov 2014] fedra, k. andfeoli, e. 1998. gis technology and spatial analysis in coastal zone management, published in: eez technology. http://www.ess.co.at/smart/public/coastal.pdf. [accessed 25 nov 2014] kelly, n.m. and tuxen, k. 2002.webgis for monitoring „„sudden oak death‟‟ in coastal california. http://kellylab.berkeley.edu/storage/papers/2002.kelly.tuxen.ceus.pdf. [accessed 10 dec 2014] http://webcache.googleusercontent.com/search?q=cache:k9g_bg_isysj:www.academicpub http://www.isprs.org/proceedings/xxxiv/part4/pdfpapers/422.pdf http://resources.arcgis.com/en/help/main/%2010.2/index.html# howkernel density http://resources.arcgis.com/en/help/main/%2010.2/index.html# howkernel density http://www.cloudcomputingdefined.com/ http://support.esri.com/en/knowledgebase/gisdictionary/ http://www.fao.org/docrep/003/x1577e/x1577e06.htm#topofpage/ http://kellylab.berkeley.edu/storage/papers/2002.kelly.tuxen.ceus.pdf 18 keenan, p.b.1997. spatial decision support systems: extending the technology to a broader user community, university college dublin, department of management information systems, belfield, dublin 4, ireland. http://mis.ucd.ie/members/pkeenan/extendsdss.pdf. [accessed 10 march 2014] kouyoumjian, v. 2010.gis in the cloud. publishing esri. http://www.esri.com/library/ebooks/gis-in the-cloud.pdf. [accessed 11 dec 2014] kulawiak, m., prospathopoulos, a., perivoliotis, l.,łubaa, m., kioroglou, s. and stepnowski, a. 2010. interactive visualization of marine pollution monitoring and forecasting data via a web based gis. http://www.sciencedirect.com/science/article/pii/s0098300410001603. [accessed 28 nov 2014] maisonneuve, m., stevens, m. and ochab, b. 2010.participatory noise pollution monitoring using mobile phones.ftp://prog.vub.ac.be/tech_report/2010/vub-tr-soft-10-14.pdf. [accessed 14 nov 2014] mann, k. 2011. fast, reliable support for disaster response, publishing esriarcuser. http://www.esri.com/news/arcuser/0311/files/cloudgis.pdf. [accessed 11 dec 2014] rajasekar, s., philominathan, p. andchinnathambi, v. 2013.research methodology. http://arxiv.org/pdf/physics/0601009.pdf. [accessed 12 dec 2014] silva, e.i.l., katupotha, j., amarasighe, o., manthrithilake, h. and ariyaratna, r. 2013. lagoons of sri lanka, international water management institute, sri lanka. william, a. 2009.the role of statistics in research.heldref publications. http://faculty.tru.ca/mreudink/methods_of_biological_inquiry/entries/2010/7/12_week_4_re dings_files/asher%201993.pdf. [accessed 26 november 2014] yilma, a.d. 2004. use of geospatial technologies for environmental protection in ethiopia. published by environmental protection authority. http://www.unoosa.org/pdf/sap/2004/sudan/presentations/07-02_2.pdf. [accessed 20 december 2014] http://mis.ucd.ie/members/pkeenan/extendsdss.pdf http://www.sciencedirect.com/science/article/pii/s0098300410001603 http://www.sciencedirect.com/science/article/pii/s0098300410001603 http://www.sciencedirect.com/science/article/pii/s0098300410001603 http://www.sciencedirect.com/science/article/pii/s0098300410001603 http://www.sciencedirect.com/science/article/pii/s0098300410001603 http://arxiv.org/pdf/physics/0601009.pdf amarasinghe & fernando/journal of tropical forestry and environment vol. 4, no 01 (2014) 80-84 80 pro-environmental behavior regarding solid waste management in householders of kalutara urban council area: a case study s.r. amarasinghe 1* and f.f.h.g. fernando 2 1 department of soil science, faculty of agriculture, university of ruhuna, sri lanka 2 national water supply and drainage board, water treatment plant, kethhena, sri lanka date received: 11-12-2013 date accepted: 23-04-2014 abstract problems generated by solid waste have become a major national issue in sri lanka due to high levels of economic growth and consumption. inappropriate management of solid waste may generate many problems such as environmental pollution, public health, social and economic problems as well as aesthetic issues. therefore, this problem needs immediate attention not only for the management of waste, but also for the study of individual behavior related to solid waste production and use. this research was carried out as a case study in kalutara urban council area, where behavior that is related to the production and management of waste is analysed. to achieve this, a questionnaire survey was conducted for the households of kalutara north, kalutara south and katukurunda. the households’ descriptive, inferential and informative believes were identified where they express agreement or disagreement regarding the final disposal of waste. in total 100 households completed the questionnaire. this work approached the behavioral aspect of the problem by considering the attitudes towards the environment and the beliefs about the environment. in addition, knowledge of environment and the problems raised have been considered for prediction of environmentally protective behavior. in this investigation, the classification of believes were considered in terms of austerity or limitation of consumption, conservation and material beliefs or material squandering. further, the environmental attitudes were considered as emotional, cognitive (know) and behavioral. based on the preliminary results of this study, it can be concluded that believes and attitudes show a certain level of relation with the behavior of the households. the questionnaire survey was useful to highlight the solid waste problem that exists in the area and to indicate the trends of attitudes and behavior among the solid waste management. further, by considering the findings of this study, an environmental education program to promote pro-environmental behavior in solid waste management must be established to change non-effective waste management practices and to promote the households to use the waste as a resource. key words: individual behavior, environmental attitudes, kalutara urban council, proenvironmental behavior, solid waste management ______________________________________________________________________________ * correspondence: sajeewani21@yahoo.com tel: +94 714835475 issn 2235-9370 print/issn 2235-9362 online © university of sri jayewardenepura amarasinghe & fernando/journal of tropical forestry and environment vol. 4, no 01 (2014) 80-84 81 1. introduction the problem of solid waste has become a global issue due to rapid industrialisation and population growth. the solid waste has great diversity of material composition and not only rising its quantity, but also changing its composition regularly. thus, it causes many problems in environmental, social and economic aspects. the work on solid waste management has two approaches namely, technical approach and behavioral approach. since, this paper mainly investigates the pro-environmental behavior which concern positive attitudes and beliefs of households in kalutara urban council area regarding the behavior on solid waste production and management. kalutara town is about 40 km away from colombo and close to the southern expressway and coastal railway line. the average annual growth rate of kalutara district has been increased at the rate of 1.26% from 1981-2001 and 1.23% from 2001-2012. according to the census of population and housing by the department of census and statistics (2001), the highest population of 37,081 was recorded in the kalutara urban council. the kalutara urban council which consists of 11 wards had highest population in hospital ward accounting 5,235. due to the high population in this area and lack of infrastructure facilities in the authorities, the proper solid waste collection is difficult. the un-segregated waste is taken to the nagoda, pohorawatta ‘mihisaru’ compost preparing centre which was under western province waste management authority and central environmental authority. however, recently the compost plant has taken action to collect only the bio-degradable waste by the urban council, while other non-biodegradable waste are dumped in to an open dumpsite belonging to the kalutara urban council. hence, the urban council has requested households to segregate waste into bio-degradable waste, plastic and polythene, cardboard and paper, and glass waste and the collection plan was commenced from 1 st may 2013. however, many complaints have arisen that the collection is not properly done as scheduled and authorities have refused to collect plastic and polythene from households. due to this unsatisfactory schedule, households inspired to burn nonbiodegradable waste which causes health hazards by inhalation of contaminated toxins and smoke from burning. the positive behavior or pro-environmental behavior against solid waste management on quality of life cannot be over-emphasised. as such, this study aims to observe the household behavior to patronise the local government and other agencies on the need of better solid waste management practices. in the case of behavioral aspect of the problem, it is vital to consider household participation in management and production of solid waste. number of studies has been done regarding this (anand, 1999; fuentes et al., 2000) which emphasize the importance of household participation in waste-reduction programmes. further, pro-environmental behavior has been studied by borden and schettino (1979) and newhouse (1990). attitudes towards the environment have been studied as predictive dispositional variables of pro-environmental behavior (ojeda & de vega, 2003). as such, knowledge of the environment has been considered as a potential predictor of environmentally protective behavior (blum, 1987; schan & holzer, 1990). in addition, the beliefs about environment have been studied by various researchers (cary, 1993). one of the most interesting pro-environmental behaviour is comprised by conservation amarasinghe & fernando/journal of tropical forestry and environment vol. 4, no 01 (2014) 80-84 82 practices (ojeda & de vega, 2003). it includes practices like reduction in energy consumption, reuse, and recycling (ebreo & vinning, 1994). since the objective of the study is to identify the pro-environmental behavior of households in production and management of solid waste in this study reuse and recycling were used as representative of conservation practices. ojeda & de vega (2003) had studied the beliefs as the term austerity. as such, we use the term limitation of consumption (austerity), conservation (optimising resources) and material beliefs. material beliefs are defined as those which favor the needs of the household over the restrictions originated by situations. 2. methodology two major local government areas are located in kalutara town; kalutara urban council area administrating concurrently with the kalutara pradeshiya sabha. the study area consists of kalutara north, kalutara south and katukurunda which is administrated by the kalutara urban council. this study area was selected because it has the highest population of 37,081 (department of census & statistics, 2001) and it is the centre of administration. the study used primary data. a questionnaire with two parts was distributed among households in the study area. one part is used for general data and the second part consists of a likert scale. for this purpose it was divided into two categories; environmental beliefs (limitation of consumption/austerity, conservation and material beliefs) and environmental attitudes (emotional, cognitive or knowledge, and behavioral). a total number of 100 households were sampled. this study would have benefitted from a higher sample size. however, due to lack of funds the sample size could not be increased. descriptive statistics such as mean, and standard deviation were used for the analysis. 3. results and discussion the likert scale was used to calculate the mean and the standard deviation. eight variables were used to determine the environmental beliefs while ten variables were used to determine environmental attitudes. the mean indicates the agreement or disagreement level to the statement presented in the sub-scale. when the sub-scale of each variable, 1 is total disagreement, 2 is disagreement, 3 is undecided, 4 is agreement, and 5 is total agreement. the results with the central tendency numbers with environmental beliefs are listed in table 1. the variables of this table are arranged according to 3 sub-scales. variables 7 and 8 are negative while other variables are positive. the analysed numbers (mean) are rounded to the closest full number i.e. 3.53 into 4 and 3.49 into 3. according to the results of limitation in consumption households show agreement in both variables. it shows that households believe that they should consume only the necessary things which will reduce the waste generation. in relation with the conservation beliefs variable 3 shows undecided while variable 4 and 5 show agreement with statements. it clearly shows that householders believe that reusing objects and separation of waste is a good practice to reduce waste. amarasinghe & fernando/journal of tropical forestry and environment vol. 4, no 01 (2014) 80-84 83 table 1: sub-scale of pro-environmental beliefs of the households in kalutara urban council. sub-scale variables mean standard deviation limitation of consumption/ austerity 1. reducing waste is a good alternative that favors the environment. 2. i should consume only the necessary things for me. 4.24 4.06 0.90 1.04 conservation 3. reusing waste means that using any object by avoiding it to be trash. 4. reusing is a part of the waste management and is an alternative which favors the environment. 5. separation of waste reduces waste generation. 3.21 3.95 3.67 1.10 0.96 1.08 material beliefs 6. recycling is an alternative of waste management and it favors the environment. 7. disposable products are indispensable in day to day life. 8. reduction of waste generation may reduce the comfort of life. 4.01 2.47 2.69 1.00 1.18 1.11 table 2 shows the results with central tendency numbers of variables of the each subscale in environmental attitudes. the construction method of the scale is similar to table 1. the positive variables of the sub-scale are 1, 5 and 8. table 2: sub-scale of pro-environmental attitudes of the households in kalutara urban council. sub-scale variables mean standard deviation emotional 1. i feel angry when my neighbors throw waste in surrounding. 2. it is a good practice if someone throws waste in any place. 3.68 1.67 1.19 0.91 cognitive (know) 3. waste in any place has no adverse effect to anyone. 4. waste problems are just local authority problems. 5. waste is a great problem for the environment. 6. waste generation without control doesn’t harm anyone. 1.72 2.16 4.07 2.12 0.90 1.24 1.27 1.24 behavioral 7. i need a lot of effort to segregate waste. 8. when someone throws waste everywhere, i take his/her attention. 9. when i saw someone throws garbage in any place, i generally do the same. 10. i am reluctant to pick up the waste which is spread out of the bin. 2.57 3.29 1.75 1.93 1.14 1.04 1.15 1.21 according to the results of table 2, it shows that in emotional, cognitive and behavioral attitudes of households are agreed when the variable subscale statement is positive (1 and 5) and disagreed when it is negative (2, 3, 4, 6, 7, 9 and 10) except in statement 8 in behavioral attitudes amarasinghe & fernando/journal of tropical forestry and environment vol. 4, no 01 (2014) 80-84 84 which shows undecided. hence, this shows that there is a resemblance between how households behave, and what they know with their emotions against waste management. the undecided statement 8 means the householders are reluctant to interfere or take action against someone who indiscriminate discharge of waste. 4 conclusions the preliminary study showed that beliefs of households including limitation of consumption (austerity), conservation by reuse and recycling have positive consequence on proenvironmental behavior. however, considering material beliefs, households are in doubt of limiting consumption that might reduce their comfort in life. according to the results of attitudes of households it is observed that there is congruence between behavior, emotions and knowledge against waste management. further, by considering the findings of this study, an environmental education program to promote pro-environmental behavior in solid waste management must be established to change non-effective waste management practices and to promote the householders to use the waste as a resource. references anand, p.b., 1999. waste management in madras revisited. environment & urbanization, 11(2):161-176. blum, a., 1987. student's knowledge and beliefs concerning environmental issues in four countries. journal of environmental education, 18:7-13. borden, r.j., schettino, a.p., 1979. determinants of environmentally responsible behavior. journal of environmental education, 10:35-39. cary, j., 1993. the nature of symbolic beliefs and environmental behavior in a rural setting. environment & behavior, 25:555-576. census 2012 results on population, dept. of census & statistics, http://www. statistics.gov.lk/ pophou sat/cph2011/accessed 12 june 2013. ebreo, a., vinning, j., 1994. conservation-wise consumers: recycling household shopping as ecological behavior. journal of environmental systems, 23:109-131. fuentes,v.r., silva, k.h., and ojeda, b.s., 2000. environmental engineering and health sciences. proposal of an environmental conscience to reduce the generation of domicilary solid waste at one urban community. water resources publications, lcc, pp.371-378. newhouse, n., 1990. implications of attitude and behavior research for environmental conservation. journal of environmental education, 22:26-32. ojeda b.s., de vega, c.a., 2003. pro-environmental behavior regarding solid waste management in students from the mexico-united states border region. web. http://www.sciencedirect.com/science/ article/pii/ s0921344903000284, accessed 14 june 2013. schan, j., holzer, e., 1990. studies of individual environmental concern. the role of knowledge, gender, and background variables. environment & behavior, 22:767-786. http://www.statistics.gov.lk/pophousat/cph2011/ http://www.statistics.gov.lk/pophousat/cph2011/ http://www.statistics.gov.lk/pophousat/cph2011/ http://www.statistics.gov.lk/pophousat/cph2011/ http://www.sciencedirect.com/science/%20article/pii/ gangadhara/ journal of tropical forestry and environment vol. 10 no. 02 (2020) 1-9 ____________________ *correspondence: gangadrr@yahoo.com tel: 0718215469 © university of sri jayewardenepura effects of regulation/ deregulation on natural resource management for market efficiency, with special reference to aggregates mining k.r. gangadhara* senior assistant secretary to the president abstract extraction or mining of geo-resources has created a much-complicated situation in terms of environmental, economic and social aspects. currently, the depletion and the environmental damage done by this extraction have become core issues in natural resources management. regulation, thus, imposed to address the resource depletion and environmental damage has been widely considered as a main instrument to manage the natural resources. however, it (regulation) is frequently criticised stating that it has a little assistance in mitigating the damage done to the environment while distorting the market efficiency, affecting ultimately the overall economic growth. yet, controversy between regulation and deregulation is highly debated over the decades. consequently, with the objective of shedding insights on the effects of regulation and deregulation on natural resource management towards market efficiency, with special reference to aggregate (sand, gravel and metal) mining; this article offers a theoretical conceptualisation how effective it is. the article put forwards both the positive and negative aspects of regulation and deregulation, and via detailed discussion, concludes that regulation in mining of geo-resources is in favor of proper management of such, but detrimental to the efficiency of the resource market. keywords: geo resources, regulation, deregulation, natural resource management, market efficiency 1. introduction earth resources, such as sand, gravel and rocks, which are aggregates in the construction industry, have been mining since the ancient times. yet, in the 20th century, the extraction of construction minerals grew by a factor of 34, while that of ores and industrial minerals by a factor of 27. this growth significantly outpaced a quadrupling of world population and a 24-fold increase in gdp (un environment, 2018). globally, between 47 and 59 billion of tonnes of earth material is mined every year of which sand and gravel account for both the largest share; from 68 per cent to 85 per cent (unep, 2014). these aggregates are encountered with fastest extraction as well, actually, with the ever-increasing demand, they are on the verge of depletion (krausmann et al., 2009). thus, the utilisation of remaining earth resources has created a much-complicated situation in terms of environmental, economic and social aspects, on top of its depletion. currently, these depletion and environmental damage have become the core issues in natural resources management. the regulations put in place to address the resource depletion and environmental damage has been publicly considered as an instrument to manage the natural resource management. however, regulatory authorities are frequently blamed for their sedentary style of interventions or poor monitoring saying regulations little helps mitigating the damage done to the environment associated with the exploitation of these resources; criticisms are also there that the stipulated rules and regulations hinder the expansion of mining industry, distorting the market efficiency, affecting ultimately the overall economic growth. 1 this conundrum between regulation and deregulation in natural resources management has led to two schools of thought. one school view that the regulation is a sound mechanism for the proper management of natural resources including mining, while the other argues that the regulation is detrimental and hence, deregulation is better for the proper management of natural resources. this article sheds some lights on both the schools of thought and supports insights on conceptualising the relationship between the regulation in natural resource management, while analysing how they are affecting to the market efficiency, with special reference to aggregates business. first, the article looks for the definitions of regulation and deregulation. secondly, the regulation and deregulation are discussed in terms of natural resources management and then for the market efficiency. finally, a theoretical conceptualisation in relation to understanding how regulation and deregulation affect with natural resources management is presented. 2. method and the postulation for the present study, it has been postulated that both the regulation and deregulation are based on sound technical principles which are fundamental to the law, but may have different implications when it applying across different sectors which are not in the doctrine of law. in this respect, it has been approached to study and compare regulation and deregulation in terms of natural resources management and then the market efficiency. 2.1 regulation and deregulation simply the regulation is the authoritative rules issued by the state (drahos, 2017). for some lawyers the meaning of regulation is confined to the rules of delegated legislation. this definition has both theoretical and empirical dimensions. empirically, regulation had pluralised in important ways, governments are pushing on third parties to deliver. in legal point of view, stipulating regulations demote the penalties for non-compliance, which is intimated as burden for the society. however, a broader view of regulation that included non-legal forms of norm-making, along with the idea that private sovereignty over such norm-making matters to regulatory outcomes. this broader view of regulation is nicely captured in the definition of regulation as ‘influencing the flow of events’ (parker and braithwaite, 2003). 2.2 regulation and natural resources management the development of international and national environmental regulations arose against a backdrop of states exercising its sovereignty over natural resources within their jurisdictions (gess, 1964). it was only natural, and also this early environmental protection of the 1970s relied on the national or at the international level, groups of states, acting primarily through treaty based intergovernmental organizations (abbott and snidal, 2009). a bundle of issues specific international rules (for example, climate change and trade in endangered species) was developed and overseen by international organizations such as the united nations environment program (kelemen and vogel, 2010). under this approach, governments believed that they understood environmental problems clearly, that they could be defined in advance and managed through mandatory rules and regulations which has flown to a minor level such as mining and logging (burca et al., 2013). when we turn our eye to an application of such regulation; consider the sand mining. governments all over the world have regulations to ban or to restrict mining sand in specific areas to limit the environmental impacts. mining operations, not only in middle income countries such as sri lanka or india but also in high-income countries such as canada, australia, finland, sweden, or even russia require obtaining environmental permits to carry out mining activities (söderholm et al., 2015). as the reduction of in-stream mining for example can be achieved by state regulation, in-stream mineral mining is strongly regulated in countries such as portugal, italy, and new zealand and is prohibited in countries such as france, the netherlands england, germany, and switzerland (kondolf, 1997). the exploitation of beach sand deposits is another issue that is solved by imposing strict rules and 2 gangadhara/ journal of tropical forestry and environment vol. 10 no. 02 (2020) 1-9 regulations. studies asserts that: “the natural sources of beach sand are decreasing, and the natural causes of sand removal are increasing” (pilkey, 2000). nevertheless, countries such as malaysia, indonesia, and vietnam try to limit beach sand exploitation by restricting or banning the export of sand to singapore, and grenada limited beach sand exploitation to a small number of beaches (beiser, 2017). to solve environmental problems related to sand exploitation, it is necessary to establish a complex regulatory system that comprises: environmental regulation, sand exploitation regulation, and land use planning regulation (rodriguez, 2017). studying the impact of sand mining in the limpopo province in south africa, dacosta and mathada (2019) emphasise the need of policy guidance and bylaws to protect and conserve the river and river valleys from destruction by sand mining. they are concerned that the legislation and regulatory setting for sand mining is vague and passive, and it makes enforcement difficult and complicated. they concern about the lack of clear and precise guidelines for dealing with sand mining operations coupled with inability of the regulatory authorities and other stakeholders that would be inevitable of uncontrolled sand mining and concomitant environmental degradation. expected implementation of the regulation limits the negative externalities of sand mining, according to them. they also suggest, even if there are no specific guidelines on sand mining operations currently imposed in countrywide, it is suggested that local municipalities come up with bylaws to help preserve the ecology of areas, and stress the concerned regulatory authorities for more serious consideration of the potential long-term consequences of widespread sand mining (dacosta and mathada, 2019). moreover, studies reveal that the particular geographic areas have had stringent regulations seem reported less illegal mining activities in comparison to areas where less regulated. koehnken et al. (2020) show that river systems that have received the most research focus, say the rivers in temperate climates in north america and europe, typically have strict regulations and are not the areas where media articles describe extensive legal and illegal mining with few controls, areas which include china, india, southeast asia, indonesia, malaysia, and bangladesh. going a step further, they further suggest rivers in the emerging economies of asia and africa urgently require research to quantify the rapidly accelerating pressures and their impacts associated with urbanisation, hydropower, and other activities, so that science-based regulations can be formulated. koehnken et al. (2020) further recommend that it must analyse the potential effectiveness of regulations to improve management of sand mining in these contexts in order to achieve a balance between economic, social, and environmental outcome, in concerned geographic areas. discussing the ecological-economic implications of deregulation of trade as promoted by the general agreement on tariffs and trade (gatt), daly and goodland (1994) argue that many environmental problems cannot be resolved equitably, efficiently, or sustainably by unregulated markets. they also stress that there is no alternative to public intervention in certain situations. the main purpose of daly and goodland (1994) work is to pay attention to the environmental risks of deregulating the trade. they outline fifteen (15) overlapping problems with deregulation or “free” trade. this includes both environmental and socio-economic factors such as standards of living and equity. finally, the authors advocate a position balanced between two extremes: regulated and deregulated “balanced trade”. this implies that prudent environmental accounting and regulation are urgently needed. quoting the unece environmental performance review (epr) it is highlighted the adequacy of the legal and regulatory basis for mining. on many occasions, epr recommendations address matters such as the adequacy of the legal and regulatory basis for the sustainable management of mineral resources (e.g., mineral exploration, exploitation, processing, mine closure, post-closure, maintenance and mineral waste recycling and recovery, the introduction of new technology to improve environmental performance, the mapping of mineral industry hot spots and the drawing up of a program to manage them, the introduction of good environmental management in the mining industry including 3 through education and training establishments, better monitoring, the creation of a national geological survey and the development of environmental assessment and auditing in the mining sector (oecd, 2018). however, gavriletea (2017) contend that, theoretically, illegal mining can be reduced by governments by setting regulation and penalties by increasing patrols in areas favorable for exploration, and by monitoring areas using performant systems. however, in practice, it is difficult to accomplish these because, usually, illegal operations take place in low-income or emerging countries where governments do not have necessary resources such as financial, human, etc. or persistent of corruption is high (gavriletea, 2017). there are countries that registered a success in their battle with illegal groups but the efforts need to continue: india has reduced its illegal sand exploitation from about 70% to about 30%. it can find solutions for problems related to sand exploitation by regulation but every solution require time and financial, human efforts and demand doesn’t take account of any of this. 2.3 deregulation and natural resources management term deregulation has increasingly been referring nowadays among policy makers as a remedy to the concerns of regulations affecting to the market efficiency, in the primary sector economy – including environment sector. central to deregulation is the ambition of greater primary sector boom with ease of doing business looking for an improved market efficiency. after the 2008 economic crash, many governments selectively removed environmental regulations to boost return on private investment and promote growth and employment, and downgraded protected area designations (apostolopoulou and adams, 2015). united states presidential campaign in 2016; the republican candidate identified environmental regulations related to mining as a major offender for unemployment. later 2017, the president of united states signed an executive order revoking us international commitment made by the previous administrations to reduce carbon emissions, and to remove restrictions “stream protection rule” which restricted expansion of coal extraction (bryenton, 2017). the president of sri lanka issued an extraordinary gazette notification to review the existing methodology of licenses issuing for mining purposes and to revisit the rules and regulations in force therein. the central argument for this notification is the difficulties faced in the procurement of earth resources for development priorities and to meet livelihood needs (extraordinary gazette, 2020). in the face of an even greater global recession caused by the covid 19 pandemic, governments are likely to take any steps necessary to maximise economic growth (sandbrook et al., 2020). currently, this could include bailing out polluting industries such as aviation, relaxing environmental standards, and opening up natural resources to exploitation—in effect spending down natural capital reserves. under this corona pandemic, many governments tend to liberalise markets while deregulating environmental laws to the removal of obstacles (that they think) to economic growth. sandbrook et al. (2020) reveal that the possible deregulated or liberalised sectors would be fossil fuels, aviation industry and mining & logging. they infer that this may increase funding available for conservation but likely to accelerate biodiversity loss, resource depletion, and increases in carbon emissions. several countries such as india and ecuador have already allowed new mining concessions in protected areas since the (covod 19) crisis began. brazil and the united states have also been reported on-going or planned disassemble of environmental regulations in high biodiversity spots (sandbrook et al., 2020). a piece of deregulation occurred in the forest administration, a different sector other than the mining, in aemenia indicates a mix of positive and negative impacts of deregulation. deregulation of the forest sector in armenia, was influenced by the world bank by introducing new planning instruments with the formal aim to strengthen the ecological goals in the natural resources management (burns et al., 2016). by employing a discourse of illegal logging and by framing local actors as the main drivers of deforestation, it has been considerably deregulated the armenian forest sector. this in turn promoted privatisation of the forest land as well as a reform of the state forest administration. these deregulations formally claimed to enhance the common goods (e.g. through strengthening 4 gangadhara/ journal of tropical forestry and environment vol. 10 no. 02 (2020) 1-9 ecological goals in natural resources management), but informally, the interventions strongly incentivised the extraction of natural resources. these reforms, however, largely benefited to provide for transnational private companies, while at the same time restricting the access of poor local users to natural resources. by establishing market models and private ownership, the deregulation policy created illegal occupation of small local actors and favoring private sector investment in armenia (burns et al., 2016). in study of smelting and refining industry in indonesia, ease of deregulation of tax structure is seen as important to the growth of the industry (shofiana and aisyah, 2020). the obstacles in the processing and refining of mining materials such as anode sludge which contributes to more taxes, in indonesia required support from various sectors. hence, shofiana and aisyah (2020) conducted an analyse to check the impact of the elimination of value added tax on mining of anode sludge using research method namely the statutory and the conceptual approach. the results showed that in eliminating the value added tax, the government could use the regular-end function. nevertheless, the elimination of value added tax provides facilities for the development of the smelter industry on the basis that the tax collection requirements must not interfere with the country's economic development. thus, it is concluded that the elimination of value added tax related to mining goods promotes the development of the industry (shofiana and aisyah, 2020). 2.4 regulation and market efficiency the economists believe that regulations distort the market efficiency which determines the welfare gain of the society. welfare gain is an essential part of the economic growth, and economic prosperity. the concept of market efficiency was first developed by fama (1970), who defined an efficient market as one in which prices fully reflected all available information. in fama's words: “the primary role of the market is the allocation of the ownership of the economy's capital stock. in general terms, the ideal is a market in which prices provide accurate signals for resource allocation: that is, a market in which firms can make production and investment decisions, and investors can choose among the securities that represent ownership of the firms' activities under the assumption that prices at any time 'fully reflect' all the available information. a market in which prices always 'fully reflect' available information is efficient.” in such an efficient market mechanism, prices would adjust rapidly and accurately to the arrival of new information, as past information is expired to predict future prices. in a regulated market environment (laws and delegated legislation), public intervention in for of regulation becomes a serious constraint and distort that market efficiency as the rule-bound procedures and the rigidity in the structure do not allow the individual and firms the flexibility to respond promptly to dynamic market conditions. and resulting to hide the proper price reflection of supply side and demand side, this (regulation) stifles competition and distorts the market efficiency and, ultimately the economic growth. 2.5 deregulation and market efficiency deregulations, in particular those that liberalise entry, are very likely to spur investment; tight regulation of product markets restricts investment (alesina et al., 2003). tight regulation of the product markets has had a large negative effect on investment. the data for sectors that have experienced significant changes in the regulatory environment suggest that deregulation leads to greater market efficiency in the long-run. while a reduction in public regulation can be seen as a reduction in the shadow cost entry. these results are robust to several sensitivity checks and extensions. interestingly, the marginal effect of deregulation depends on how deep the change is: more decisive regulatory reforms have a greater marginal impact (alesina et al., 2003). moreover, deregulation improves economic welfare, and the improvement builds over time (crandall 2016). since the 1970s, deregulation has succeeded in increasing overall economic welfare and sharply reducing prices. the 25-year deregulation movement that began in the 1970s had a remarkable impact on the united states and many other countries. in the united states, the entire 5 national transportation sector was substantially deregulated; the energy, financial, and video distribution sectors were heavily deregulated and even telecommunications witnessed considerable deregulation and regulatory reform. about two-thirds of the communications sector (including long distance services, broadband services, telephone terminal equipment, and cable television) has been deregulated, while local telephone service and broadcasting are still regulated. overall, the amount of regulation has fallen by roughly 74% (crandall, 2016). after the first oil shock of 1973, the developed economies experienced a dramatic decline in their economic growth (nordhaus, houthakker, and sachs, 1980; sachs, 1982) and labour productivity growth (baily, gordon, & solow, 1981). since mid-1970s, the productivity decline triggered a wide range of policy responses, including economic deregulation. deregulation initiated in the us (winston, 1998; morgan, 2004), soon followed by the uk and other developed economies in the early 1980s (pera, 1988; healey, 1990; matthews, minford, nickell, and helpman, 1987) and were imitated by the new democracies and many developing countries in the 1990s with an extensive set of labour, capital, and product-market reforms. the process continued throughout the early years of the 21st century (wölfl, wanner, kozluk, and nicoletti, 2009) until the recent (2008) global economic and financial crisis. the deregulation softens trade and capital borders, and introduces more complexity to the processes of global economic growth (and recession). with the global movements of information and resources while possessing the connectivity with each other, the point shock of the system cannot be concealed within the particular affected system. this is the nature of systemic risk. the impact of these systemic booms and busts is not borne equally by all; marginalised communities bear the burden of these globalised, deregulated systems more. for instance, case studies of the impacts of financial deregulation, environmental deregulation, and labour safety enforcement outsourcing bear the witnesses for this disappointing truth. the movement towards over deregulated economic system has experienced the consequence of exploitation. 2.6 effects of regulation and deregulation on natural resource management for market efficiency initially, governments and their agents managed environmental problems through enforcement of strict rules and standards set out in legislation and treaties (gunningham, 2009). however, with the rise of neoliberal ideals in the 1980s, governments began to shift their attention away from this westphalian sovereignty of state power. instead, environmental degradation was, in many cases, to be curbed via market-based approaches, voluntarism and other ‘light-handed’ policy initiatives such as partnerships and cooperation yet, by the end of the 1990s, continuing ecological degradation and the increasing complexity of social and environmental problems saw a new shift towards environmental governance (driessen et al., 2012) or what is increasingly being called ‘new environmental governance’ (holley et al., 2012). the new environmental governance (neg) emphasised collaboration, integration, participation, deliberative styles of decision-making, adaptation and learning. neg may equally be described as polycentric governance, where governments, non-governmental organizations, the private sector and civil society form many centers of decision-making and action that are formally independent of each other, but that can either function independently or constitute an interdependent system of relations (ostrom, 2010). although neg is still an evolving concept, a growing number of scholars and policymakers believe it can substantially improve the effectiveness, efficiency and legitimacy of responses to environmental problems. the environmental governance landscape has changed significantly over the last 40 years, but it remains multifaceted as it is covered by new and old policy approaches (dryson et al., 2012). a good example for this change is the present-day response to climate change, which involves not only marketbased instruments, but also hierarchy, as well as neg approaches (dryzek et al., 2011). in the anthropocene, the trajectory of governing environmental problems is far from complete, as, 6 gangadhara/ journal of tropical forestry and environment vol. 10 no. 02 (2020) 1-9 environmental governance remains something of an ongoing experiment, suggesting there is all the more reason to learn now from both successes and failures so we can build a more effective and democratic approach for environmental governance in the future. 3. conclusion regulation or deregulation can only be discussed in a particular doctrine which are identical to each other, and if perform in different platforms results wouldn’t be same. regulation in natural resources management compromises the resources availability (minimise the depletion) and the sustainability of the environment, but distort the growth of the industry-market efficiency. deregulation in natural resources management improve the market efficiency and also the ease of doing business in primary sector including mining, but affect the nature. references abbott, k. and snidal, d., 2009. ‘strengthening international regulation through transmittal new governance: overcoming the orchestration deficit. journal of vanderbilt law, 42:501-78. abbott, k.w. and snidal, d., 2008. the governance triangle: regulatory standards institutions and the shadow of the state. the politics of global regulation: princeton university press. alesina, a., ardagna, s., nicoletti, g. and schiantarelli, f., 2005. regulation and investment. journal of the european economic association, 3:791-825. andbrook, c.s., omez, e.g., baggethun and william, a. a., 2020. biodiversity conservation in a post-covid-19 economy. in: fauna and flora international. s.l.: cambridge university press, pp. 2-8. apostolopoulou, e. and adams, w.m., 2015. neoliberal capitalism and conservation in the post‐crisis era: the dialectics of “green” and “un‐green” grabbing in greece and the uk. antipode, 47:1535. beiser, v., 2017. sand mining: the global environmental crisis you’ve probably never heard of. the guardian. https://www.theguardian.com/cities/2017/feb/27/sand-miningglobalenvironmental-crisis-never-heard. accessed 26 april 2020. braithwaite, j., 2000. global business regulation. cambridge: cambridge university press. braithwaite, j., elgar, e. and cheltenham, 2008. regulatory capitalism: how it works, ideas for making it work better. s.l.:s.n. bryenton, r.g., 2017. the impact of environmental regulations on the west virginia coal economy: assessing the “coal means jobs” mantra and the prospect of deregulation. s.l.: senior capstone projects. 633. burns, s.l., krott, m., sayadyan, h. and giessen, l., 2017. the world bank improving environmental and natural resource policies: power, deregulation, and privatization in (post-soviet) armenia. world development, 92:215-224. crandall, r.w., 2016. extending deregulation make the u.s. economy more efficient. washington dc: the brookings institution. daly, h. and goodland, r., 1994. an ecological-economic assessment of deregulation of international commerce under gatt part i. population and environment, 15:395-427. de búrca, g., keohane, r.o. and sabel, c., 2014. global experimentalist governance. british journal of political science, 477-486. democratic socialist republic of sri lanka, 2020. extraordinary of the gazette of the, no. 2196/28. drahos, p., 2017. regulatory theory foundations and applications. s.l.:anu press the australian national university, pp. 1-8, 741. eggert, r.g., 1994. mining and the environment: international perspectives on public policy, resources for the future. washington dc: s.n. francis, f.a. and mathada, h., 2017. study of sand mining and related environmental problems along the nzhelele river in limpopo province of south africa”. mine water and circular economy, lappeenranta, finland. 7 gavriletea, d.m., 2017. environmental impacts of sand exploitation. analysis of sand market”, sustainability (issn 2071-1050; coden: sustde, mdpi (basel, switzerland). gess, k., 1964. ‘permanent sovereignty over natural resources’, international and comparative law quarterly 13:398-449. gunningham, n. and holley, c., 2016. next generation environmental regulation: law, regulation, and governance. annual review of law and social science, 12. gunningham, n. and sinclair, d., 2002. leaders and laggards: next generation environmental regulation. sheffield: greenleaf publications. gunningham, n., 2009. environment law, regulation and governance: shifting architectures. journal of environmental law, 21:179-212. hawkins, k., 1984. environment and enforcement: regulation and the social definition of pollution. oxford: clarendon press. hawkins, k., 2002. law as last resort: prosecution decision-making in a regulatory agency. new york: oxford university press. hodzic, s. and celebi, h., 2017. ‘value-added tax and its efficiency: eu-28 and turkey. utms journal of economics, 8:79-90. holley, c., gunningham, n. and shearing, c., 2012. the new environmental governance. new york: earthscan. kelemen, r.d. and vogel, d., 2010. trading places: the role of the united states and the european union in international environmental politics. comparative political studies, 43:427-456. koehnken, l., rintoul, m.s., goichot, m., tickner, d., loftus, a.c. and acreman, m.c., 2020. impacts of riverine sand mining on freshwater ecosystems: a review of the scientific evidence and guidance for future research. river research and applications, 36:362-370. kondolf, g., 1997. hungry water: effects of dams and gravel mining on river channels. environmental management, 21:533-551. krausmann, f., gingrich, s., eisenmenger, n., erb, k.h., haberl, h. and fischer-kowalski, m., 2009. growth in global materials use, gdp and population during the 20th century. ecological economics, 68:2696-2705. ma, d., fei, r. and yu, y., 2019. ‘how government regulation impacts on energy and co2 emissions performance in china's mining industry, resources policy, 62:651-663. malkiel, b.g. and fama, e.f., 1970. efficient capital markets: a review of theory and empirical work. the journal of finance, 25:383-417. morgan, i., 2004. jimmy carter, bill clinton, and the new democratic economics. historical journal, pp. 1015-1039. organisation for economic co-operation and development, 2018. unece and responsible mining. andré pascal 75016 paris: oecd environment. parker, c. and braithwaite, j., 2003. ‘regulation’, in: p cane and m tushnet, the oxford handbook of legal studies. s.l.:oxford university press, pp. 119-145. pilkey, o., 2000. what you know can hurt you: predicting the behaviour of nourished beaches. in: science and policy. in: d. p. r. j. b. r. j. sarewitz, ed. prediction: science, decision making, and the future of nature. washington, dc, usa: island press, p. 159-184 rodriguez, r., 2017. sand and gravel resources of puerto rico. https://pubs.usgs.gov/fs/sandgravel. accessed 26 april 2017. sachs, j., 1982. stabilization policies in the world economy: scope and skepticism (no. w0862). national bureau of economic research. sandbrook, c., 2020. covid and conservation on the ground. thinking like a human blog, 2020 05. thinkinglikeahuman. shofiana, r. and aisyah , s.h., 2020. elimination of value added tax on mining (anoda sludge) in indonesia. palarch’s journal of archaeology of egypt/egyptology 17:1902-1908. söderholm, k., söderholm, p., helenius, h., pettersson, m., viklund, r., masloboev, v., mingaleva, t. and petrov, v., 2015. environmental regulation and competitiveness in the mining industry: 8 gangadhara/ journal of tropical forestry and environment vol. 10 no. 02 (2020) 1-9 permitting processes with special focus on finland, sweden and russia. resources policy, 43:130-142. undp and un environment, 2018. managing mining for sustainable development: a sourcebook. bangkok: united nations development programme. unep, 2014. “sand, rarer than one thinks”. thematic focus: ecosystem management, environmental governance, resource efficiency, sioux falls. wölfl, a., wanner, i., kozluk, t.j. and nicoletti, g., 2009. ten years of product market reform in oecd countries-insights from a revised pmr indicator. wolkersdorfer c, c., sartz , l., sillanpää, m. and häkkinen, a., 2017. finland mine water and circular economy. lappeenranta: imwa. 9 subasinghe & haripriya/journal of tropical forestry and environment vol. 4, no 01 (2014) 40-49 40 prediction of stem biomass of pinus caribaea growing in the low country wet zone of sri lanka s.m.c.u.p. subasinghe 1* and a.m.r. harpriya 2 1 department of forestry and environmental science, university of sri jayewardenepura, sri lanka 2 divisional forest office, puttlam, sri lanka date received: 06-01-2013 date accepted: 22-01-2014 abstract forests are important ecosystems as they reduce the atmospheric co2 amounts and thereby control the global warming. estimation of biomass values are vital to determine the carbon contents stored in trees. however, biomass estimation is not an easy task as the trees should be felled or uprooted which are time consuming and expensive procedures. as a solution to this problem, construction of mathematical relationships to predict biomass from easily measurable variables can be used. the present study attempted to construct a mathematical model to predict the stem biomass of pinus caribaea using the data collected from a 26 year old plantation located in yagirala forest reserve in the low country wet zone of sri lanka. due to the geographical undulations of this forest, two 0.05 ha sample plots were randomly established in each of valley, slope and ridge-top areas. in order to construct the model, stem wood density values were calculated by using stem core samples extracted at the breast height point. stem volume was estimated for each tree using newton’s formula and the stem biomass was then estimated by converting the weight of the known volume of core samples to the weight of the stem volume. prior to pool the data for model construction, the density variations along the stem and between geographical locations were also tested. it was attempted to predict the biomass using both dbh and tree height. apart from the untransformed variables, four biologically acceptable transformations were also used for model construction to obtain the best model. all possible combinations of model structures were fitted to the data. the preliminary model selection for further analysis was done based on higher r 2 values and compatibility with the biological reality. out of those preliminary selected models, the final selection was done using the average model bias and modeling efficiency quantitatively and using standard residual distribution qualitatively. after the final evaluation the following model was selected as the best model to use in the field. keywords: allometric equations, forest biomass, non-destructive sampling, pinus caribaea ______________________________________________________________________________ * correspondence: upuls@sjp.ac.lk tel: +94 112804685 issn 2235-9370 print/issn 2235-9362 online © university of sri jayewardenepura subasinghe & haripriya/journal of tropical forestry and environment vol. 4, no 01 (2014) 40-49 41 1. introduction global climate change has inspired an increasing interest of scientific and political communities in the study of global carbon storage and of the carbon balance (landsberg et al., 1995). the estimation of biomass is an essential aspect of studies of carbon storage and carbon balance (xiao & ceulemans, 2004). forests play an important role in global carbon budget as carbon sinks and throughout emission of co2 (dixon et al., 1994; sedjo et al., 1997). carbon is stored in trees as biomass and therefore biomass assessments play a major role in determining carbon storage in forests. forests hold two third of terrestrial c and as the forest biomass increase over the time, so does the stock of sequestered c in the standing forest and soils. estimation of biomass of a sample of trees can be very difficult and expensive. at most, it involves felling the trees, excavating their root systems and drying and weighing the biomass. such practices may be impossibly expensive and therefore much attention has been paid to the development of techniques to estimate tree biomass from easily measured tree characteristics. these techniques, known generally as allometry, involve relationships between tree aboveground biomass and tree stem diameter and/or height and above-ground biomass (specht & west, 2003). in 1994, niklas said that allometry, relating easily measured variable to other structural and functional characteristics, is the most common and reliable method for estimating biomass, net primary production, and biogeochemical budgets in forest ecosystems (gower et al., 1999; wang, 2006). mostly allometry employs diameter at breast height (dbh) as the only independent variable, and develops an allometric relationship between dbh (gower et al., 1999). however, such models can further be improved by adding one or more additional independent variables. therefore some studies proposed to include tree height as the second predictor (e.g. wang, 2006). the use of allometric relationships yields a non-destructive and indirect measurement of biomass compartments, and is often the preferred approach since it is less time consuming and less expensive than direct measurements (st. clair, 1993). in addition to that, such methods prevent damaging the forest ecosystems or environment due to felling or excavation of trees. among temperate forests, pine stands are considered one of the most productive forests. mean carbon values for pine stands have been reported to range from 3 to 161 t ha -1 , depending on stand age, type and number of carbon pools included in the reported inventory (e.g. forrest & ovington, 1970; kinerson et al., 1977; johnson et al., 2003). pinus caribaea was introduced to the wet zone of sri lanka in 1970s to rehabilitate the degraded lands resultant due to deforestation. the other objectives of planning pines in sri lanka were to protect the watersheds, control soil erosion, stabilise slopes and to obtain pulp and timber. however, according to weerawardene et al. (1998), some of the above mentioned objectives have not been achieved due to various reasons. one reason was the lack of sufficient demand for pine timber and pulp in sri lanka due to the low density of wood. the high resin content of the wood adversely affects the pulp production and expensive technology should be used to remove the resins from the wood. due to this reason, harvesting schedules were delayed probably causing some environmental problems such as over-crowded stands of trees possibly lowering the water table excessively reducing the timber quality, creating a dense mat of pine leaves on the ground etc. subasinghe & haripriya/journal of tropical forestry and environment vol. 4, no 01 (2014) 40-49 42 2. study area and sampling the present study was carried out in the 26 year old p. caribaea monoculture plantation of the yagirala forest reserve which is situated in the south-western part of the wet zone in sri lanka. the extent of this forest is 2,000 ha and it is located between n 06 0 20 / -06 0 22 / to e 80 0 10 / 80 0 12 / in kalutara administrative district in the low country wet zone. the area receives 4,000 mm annual rainfall and the mean temperature is about 27-28.5 0 c. yagirala forest reserve had extensively been subjected to timber harvesting in 1970s. due to this reason, large gaps were created and those were replaced by establishing monoculture p. caribaea plantations. among those pine blocks, a 25 ha p. caribaea block was selected for data collection for the present study. this area had an undulating ground with valleys, slopes and ridge tops. although there were no visual growth differences within the selected area, it was decided to use stratified random sampling as two 0.05 ha circular sample plots from each of valley, slope and ridge top. thereby six sample plots were used for the data collection. 3. methodology 3.1 theoretical model structure stem of living trees grows both horizontally and vertically. biomass accumulation also occurs in trees in both directions. the horizontal growth can be measured by the diameter at breast height (dbh) and the vertical growth can be measured by the total tree height. therefore it was assumed that the biomass was a function of both dbh and total height as shown in equation 1. biomass = f dbh, total height (1) the relationship shown in equation 1 was used to construct a model to predict the main stem biomass of p. caribaea in this study. 3.2 samplings and measurements the 25 ha pine block was divided into three strata as valley, mid-slope and ridge based on the geographical variations. two circular sample plots of 0.05 ha were randomly laid in each stratum to collect the necessary data. dbh and total height of all p. caribaea trees in each sample plot were accurately measured using a diameter tape and an altimeter respectively. newton’s formula was used to estimate the precise stem volumes for this study (philip, 1994; subasinghe, 1998). in order to apply the newton’s formula, standing trees were divided into sections less than 5 m and base, top and mid diameters and length of each section were accurately measured. spiegal relescope was used for diameter measurements and an altimeter was used for length measurements in this exercise. then the volume for each section was separately estimated using newton’s formula. the top most section was assumed as a cone and the volume was estimated accordingly. in order to calculate the total stem volume, the section volumes were added together as shown in equation 2. subasinghe & haripriya/journal of tropical forestry and environment vol. 4, no 01 (2014) 40-49 43 fitot vvv  (2) where: vf = volume of the final section (cone), m 3 vi = volume of the each section, m 3 vtot = total stem volume, m 3 3.3 estimation of stem biomass a non-destructive sampling method was used in the present study to estimate the stem biomass. the biomass estimation was therefore done by converting a volume and weight (density) of a core sample extracted by an increment borer at the breast height point in to the stem biomass via stem volume. the length of the stem core extracted using the increment borer was accurately measured in millimetres. core diameter was measured for randomly selected core samples and the average was taken because only one increment borer with one extraction tube was used for the entire study. the core samples were oven-dried at 105 0 c for 72 hours and then the weight was measured. 3.4 volume of the core shape of the core sample was cylindrical and therefore the equation 3 was employed to estimate the core volume. 9 2 104  ld v s s  (3) where: ds = diameter of the core sample, mm l = length of the core sample, mm vs = volume of the core sample, m 3 3.5 estimation of the main stem biomass dry weight of the core sample was measured in grams using an electronic balance. stem biomass, i.e., the dry weight of the stem was calculated by using the equation 4. s totd tot v vw w   (4) where: vtot = total stem volume, m 3 wd = oven dry weight of the core sample, kg wtot = total biomass of the stem, kg subasinghe & haripriya/journal of tropical forestry and environment vol. 4, no 01 (2014) 40-49 44 3.6 testing the stem density difference of trees growing in different locations although there was no visual growth difference observed in different locations of the selected area, the difference of the stem wood density of the trees growing in different locations, i.e., valley, slope and ridge top was tested using one-way anova at 95% probability level. 3.7 determination of stem wood density differences along the main stem apart from the core samples taken at the breast height point, core samples were extracted at the mid-length of the stems of four randomly selected trees in each plot. the stem wood density was calculated for these core samples taken at the mid-lengths using the method described in section 3.3. finally the density differences between at the breast height point and at the mid-length of the stems were tested using one sample t-test at 95% probability level. 3.8 construction of relationships between biomass and other variables regression analysis was employed to develop the relationship between biomass and the selected explanatory variables, i.e., dbh and total height. apart from the untransformed variables, it was decided to use four transformations which are biologically accepted, i.e., logarithmic, square root, square and reciprocal to obtain the models with the minimum bias and the highest efficiency. thereby all possible combinations of variables were tested to obtain the best model to predict the stem biomass. coefficient of determination (r 2 ) was initially used to identify the possible candidate models. apart from the accuracy of model fitting, the compatibility with the biological reality was tested by employing the following theory (source: subasinghe, 1998). if the height of the tree moves to zero (h  0), dbh should be zero (dbh = 0). in this case, biomass of the stem should also be zero (wtot = 0). therefore the intercept of the selected model should be zero or at least it should not be significantly different from zero. therefore the preliminary model selection was based on higher r 2 values and insignificant intercepts. then they were further tested for the bias and modelling efficiency using the equations 5 and 6 and using standard residual distribution. n yy bias ii )ˆ(   (5) where: n = number of data i y = measured biomass used for the model building i ŷ = predicted biomass from the model 2 2 )( )ˆ( 1 yyi yy me ii    (6) where: me = modelling efficiency y = mean measured biomass subasinghe & haripriya/journal of tropical forestry and environment vol. 4, no 01 (2014) 40-49 45 4. results 4.1 plot summary as described in the methodology, six plots were established in the randomly selected positions to collect data. the summary of the data is given in table 1. table 1: summary of the collected data. site plot no no of trees mean dbh, cm mean height, m mean volume, m 3 mean density, kgm -3 valley valley 1 2 34 22 19.3 20.1 18.2 20.1 0.287 0.306 549.0 539.1 slope slope 3 4 14 27 23.7 21.2 23.1 21.9 0.457 0.367 596.2 581.2 ridge top ridge top 5 6 35 46 21.5 19.9 20.2 18.7 0.351 0.253 572.5 571.6 the visual observations of the mean values appeared to be similar irrespective of the location of the plots. however, there was a difference between the numbers of trees in different locations. 4.2 difference of stem wood density of trees growing in different locations one-way anova was usd at 95% probability level to investigate the significance of the wood density at breast height of the trees growing in different locations. the results were not significant and it proved that there was no difference of the stem density of the trees growing in different locations (f=2.16 and p=0.061). due to this reason, it was possible to pool all data for model construction. 4.3 difference of mid-length density and density at the breast height according to the results of the two sample t-test, there was no significance difference between the stem wood density at the mid-length of the stem and the stem wood density at the breast height (t=1.57 and p=0.130). therefore the density values calculated by using the core samples taken at the breast height were used as the wood density of the entire stem of p. caribaea. 4.4 model construction to predict stem biomass from other variables relationships between stem biomass of p. caribaea and other candidate easily measurable variables were developed using regression analysis. as mentioned in section 3.8, other than the untransformed values, the variables were transformed to four biologically accepted forms. the preliminary evaluation of the resultant models was tested using r 2 and compatibility with biological reality as mentioned in section 3.8. the preliminary selected models for further analysis are given in table 2. subasinghe & haripriya/journal of tropical forestry and environment vol. 4, no 01 (2014) 40-49 46 all models listed in table 2 had non-significant intercepts and high r 2 values. however, apart from model 3 and 4, all other models indicated poor or very poor standard residual distributions. both models 3 and 4 of table 2 had the square root transformed response variable, i.e., biomass. due to the fact that the intercepts of both models were non-significant, it was possible to re-fit them to the same data without intercepts. the resultant models are given in table 3. table 2: preliminary selected models for further analysis. model no model r 2 residual 1 2 3 4 5 6 7 84.6 86.4 86.2 86.2 79.9 79.6 80.2 poor poor good good very poor very poor very poor table 3: results of the re-fitted models 3 and 4 without intercepts. new model no old no in table 2 model average model bias modelling efficiency 8 9 3 4 -0.023 -0.003 86.0% 86.0% according to table 3, both models had insignificant bias and equally high modelling efficiencies. therefore the selection of the final model was done based on the distribution of standard residuals (fig. 1 and 2). fig. 1: standard residual distribution against the fitted values of model 8 of table 3. -5.00 -4.00 -3.00 -2.00 -1.00 0.00 1.00 2.00 3.00 4.00 5.00 0.00 5.00 10.00 15.00 20.00 25.00 30.00 s ta n d a rd r e si d u a ls fitted values subasinghe & haripriya/journal of tropical forestry and environment vol. 4, no 01 (2014) 40-49 47 the residual distribution of model 9 of table 3 (fig. 2) appeared to be non-random. in fact, the residuals spread diagonally from lower left corner of the graph towards to top right corner. such a pattern, however, was not observed in model 8 of table 3 (fig. 1) and therefore the residuals of model 8 proved random distribution. therefore based on the standard residual analysis, it was decided that the model 8 given in equation 7 as the best one to use in the field. (7) where: dbh = breast height diameter, cm h = total tree height, m w = biomass of the main stem of p. caribaea, kg fig. 2: standard residual distribution against the fitted values of model 9 of table 3. 5. discussion forests can be considered as carbon sources and sinks. therefore the management of the forests can maintain the global carbon cycle and climate change. according brown et al., (1992), about 50% of the biomass of trees is carbon. however, subasinghe & munasinghe (2011) found higher carbon percentages than 50% for all above ground components in their study conducted for pinus caribaea growing in the wet zone of sri lanka. the greatest potential for aboveground biomass and carbon storage in forest ecosystems is usually found within the tree biomass components (stem, branches, and foliage). biomass of understory and ground vegetation, as well as of dead standing trees and woody debris, may also provide a considerable contribution (peichl & arain, 2006). however, being a coniferous tree, p. caribaea does not produce large branches or a large amount of leaves. therefore its main stem contributes most to the above ground biomass and thereby to the carbon storage. apart from aboveground vegetation, belowground tree root biomass, forest floor, and mineral soil provide large carbon pools (johnson et al., 2003; oliver et al., 2004). however, due to an immense effort required in obtaining a precise estimate of tree root biomass, it is often neglected or estimated from standard root to shoot ratios (kurz et al., 1996; cairns et al., 1997). -5.00 -4.00 -3.00 -2.00 -1.00 0.00 1.00 2.00 3.00 4.00 5.00 0.00 5.00 10.00 15.00 20.00 25.00 30.00 s ta n d a rd r e si d u a ls fitted values subasinghe & haripriya/journal of tropical forestry and environment vol. 4, no 01 (2014) 40-49 48 most forest biomass studies conducted in the past used destructive sampling to analyse biomass and/or carbon values of different tree components (e.g., parde, 1980; guo et al., 2002; xiao & ceulemans, 2004; williams & gresham, 2006). use of destructive sampling is not possible for the present study due to the difficulty of obtaining selective harvesting approval from the government forest plantations. therefore it used a core sample analysis to estimate the biomass of the main stem and therefore much attention has been paid to the development of techniques to estimate tree biomass from easily measured tree characteristics. these techniques, known generally as allometry, involve relationships between tree above-ground biomass and tree stem diameter and/or height and above-ground biomass (spelcht & west, 2006). references brown, s., lugo, a.e., 1992. above ground estimates for tropical moist forests of the brazilian amazon. interciencia, 17(1):8-27. cairns, m.a., brown, s., helmer, e.h., baumgardner, g.a., 1997. root biomass allocation in the world’s upland forests. oecologia, 111:1–11. dixon, r.k., brown, s., hougton, r.a., solomon, a.m., trexler, m.s. and wisniewski, j., 1994. carbon pools and flux of global forest ecosystems, science, 263:185-190. forrest,w.g., ovington, j.d., 1970. organic matter in an age series of pinus radiata plantations. journal of applied ecology, 7:177-189. gower, s.t., kucharik, c.j., norman, j.m., 1999. direct and indirect estimation of leaf area index, f(apar), and net primary production of terrestrial ecosystems. remote sensing & environment, 70:29-51. guo, l.b., sims, r.e.h., horne, d.j., 2002. biomass production and nutrient cycling in eucalyptus short rotation energy forests in new zealand i: biomass and nutrient accumulation. bioresource technology, 85:273-283. johnson, d.w., todd jr., d.e., tolbert, v.r., 2003. changes in ecosystem carbon and nitrogen in a loblolly pine plantation over the first 18 years. soil science society of america journal, 67:1594-1601. kinerson, r.s., ralston, c.w., wells, c.g., 1977. carbon cycling in a loblolly-pine plantation. oecologia, 29:1-10. kurz, w.a., beukema, s.j., apps, m.j., 1996. estimation of root biomass and dynamics for the carbon budget model of the canadian forest sector. canadian journal of forest research, 26:1973-1979. landsberg, j.j., linder, s., mcmurtrie, r.e., 1995. effects of global change on managed forests. a strategic plan for research on managed forest ecosystems in a globally changing environment. global change and terrestrial ecosystems. core project of the igbp, canberra, pp.1-17. niklas, k.j., 1994. plant allometry: the scaling of form and process. university of chicago press, chicago, illinois. oliver, g.r., pearce, s.h., kimberly, m.o., ford-robertson, j.b., robertson, k.a., beets, p.n., garrett, l.g., 2004. variation in soil carbon in pine plantations and implications for monitoring soil carbon stocks in relation to land-use change and forest site management in new zealand. forest ecology & management, 203:283-295. parde, j., 1980. forest biomass. forestry abstracts, 41(8):343-362. subasinghe & haripriya/journal of tropical forestry and environment vol. 4, no 01 (2014) 40-49 49 peichl, m and arain, m.a., 2006. aboveand belowground ecosystem biomass and carbon pools in an age-sequence of temperate pine plantation forests. agricultural & forest meteorology, 140:51-63 philip, m.s., 1994. measuring trees and forests, 2nd ed. cambridge university press, uk sedjo, r.a., wisniewski, j, and sampson, r.n., 1997. economics of carbon sequestration in forestry, lewis publishers, boca raton. specht, a., west, p.w., 2003. estimation of biomass and sequestered carbon on farm forest plantations in northern new south wales, australia. biomass & bioenergy, 25:363 379. st. clair, j.b., 1993. family differences in equations for predicting biomass and leaf area in douglas fir (pseudotsuga menziesii var. menziesii). forest science, 39:743-755. subasinghe, s.m.c.u.p., 1998. construction of growth models for pinus nigra var. maritima (ait.) melville (corsican pine) in great britain, ph.d. thesis, university of wales bangor, uk. subasinghe, s.m.c.u.p., munasinghe, g.b., 2011. estimation of above ground tree biomass and carbon of pinus caribaea (morelet). journal of tropical forestry & environment, 01(01):57-71. xiao, c. and ceulemans, r., 2004. allometric relationships for below and aboveground biomass of young scots pines. forest ecology & management, 203:177-186. wang, c., 2006. biomass allometric equations for 10 co-occurring tree species in chinese temperate forests. forest ecology & management, 222:9-16. weerawardene, n.d.r., malcolm, d.c., longman, k.a., 1998. converstion of pine plantations to be under-planting in sri lanka: possibility and constraints. sri lanka forester, 23(1-2): 61-63. williams, t.m., gresham, c.a., 2006. biomass accumulation in rapidly growing loblolly pine and sweet gum. biomass & bioenergy, 30:370-377. senevirathna & perera /journal of tropical forestry and environment vol. 3, no. 02 (2013) 1-10 1 feature article wildlife viewing preferences of visitors to sri lanka’s national parks: implications for visitor management and sustainable tourism planning h.m.m.c. senevirathna* and p.k.p. perera department of forestry and environmental science, university of sri jayewardenepura, nugegoda, sri lanka 1. introduction tourism is the largest service-sector industry in the global economy, and plays a key role in destination development, especially in developing countries. tourism industry has long been a key player in the sri lankan economy. traditionally, sri lanka‟s tourism industry has been oriented towards sea, sand and sun tourism (3s tourism). however, when compared with other popular tourism destinations in the region, sri lanka has diverse tourism opportunities to offer. sri lanka at present is in a rapid post-war recovery process, and the country‟s tourism sector is also booming rapidly. reflecting this positive growth, tourism sector‟s contribution to the country‟s gdp has increased from 2.7% in 2009 to almost 3% in 2010, primarily due to the strong growth in tourist arrivals and spending (icra, 2011). the interest on sri lanka as a travel destination has grown tremendously during the post-war period. for instance, the new york times ranked sri lanka at the top in it‟s “the 31 places to go in 2010” travel article (nytimes.com 2010). the national geographic channel has also rated sri lanka as the second best place to visit in its travel documentary “world's twenty best tourist destinations” (national geographic channel 2010). more recently, “lonely planet”, a leading travel and tourism information source rated sri lanka at the top in its “best in travel 2013 top 10 countries” list (lonelyplanet.com, 2012). interestingly, all these sources have highlighted nature-based attributes and biodiversity as major attractions in sri lanka. sri lanka boasts having the highest biodiversity per 10,000 km 2 in asia, and it is also rated as one of the 25 biodiversity hot spots in the world (ministry of environment and natural resources, 2002). at the same time, sri lanka also has a highly sophisticated protected area network managed under department of wildlife conservation (dwlc) and forest department (fd), where an area of over 1,710,000 hectares accounting for 26.5% of the land area of the country is legally protected. these protected areas (pas) along with other natural landscapes provide diverse nature tourism opportunities within the country. however, when considered the diverse natural and cultural resources, sri lanka‟s tourism resources still remain relatively under-exploited. instead, most nature-based tourism activities are concentrated on few well-known destinations such as certain national parks (nps) and forest reserves. as a result, these sites are continuously subjected to increased visitor pressure. hence, research focused on introducing better management strategies to alleviate negative impacts of tourism on highly visited nature-based destinations should be prioritized in the sustainable tourism research agenda. this article explores the recent developments in nature-based tourism in sri lanka‟s pas and discusses the use of understanding wildlife viewing preferences of visitors in introducing visitor management strategies, and recreational planning in pas. *correspondence: madu87feb@gmail.com tel: +94-112758411, fax: +94 112803470 issn 2235-9370 print / issn 2235-9362 online ©2013 university of sri jayewardenepura senevirathna & perera /journal of tropical forestry and environment vol. 3, no. 02 (2013) 1-10 2 2. sri lanka’s protected area network the history of wildlife protection and pa establishment in sri lanka goes back to 246 bc where king devanam piyatissa established one of the world‟s earliest wildlife sanctuaries in anuradhapura (wijesinghe, 2003). contemporary history of legal protection of flora and fauna in the country dates back to 1889 where colonel r.a. clark, the conservator of forests pushed the government of ceylon to introduce immediate legislations forbidding the killing of wild animals and export of hides. continued efforts of mr. a.f. broun resulted in government of ceylon declaring yala (160 sq. miles) and wilpattu (256 sq. miles) as reserves under the forest ordinance (dwlc, 2012). since then, the pa network in sri lanka has systematically expanded to include over 26% of the total land area of the country. sri lanka‟s pas are mainly administered by two state institutions; the forest department and the department of wild life conservation. from the total land area of the country, approximately 13% is conserved under the dwlc. this are comprise of 61 sanctuaries, 22 national parks, 4 nature reserves, 3 strict nature reserves and 1 jungle corridor (ministry of economic development, 2011). the forest department manages 65 conservation forests and one national heritage and wilderness area (table 1). accordingly, a total area of 1,767,000 ha accounting for 26.5% of the land area in the country is legally protected. this is comparatively a higher percentage of protected areas than other countries in asia. table 1: protected areas administrated by the forest department and department of wildlife conservation protected area category area under each category (ha) in 2010 forests under the forest department (fd) national heritage wilderness area [n = 1] 11,127 conservation forests [n = 65] 96,249 other reserved forests [n = 366] 630,701 forest plantations 79,941 total areas under the fd 818,018 forests under the department of wildlife conservation (dwlc) national parks [n=22] 526,156 nature reserves [n=4] 57,056 sanctuaries [n=61] 349,105 strict natural reserves [n=3] 31,575 jungle corridors [n=1] 8,777 total areas under the dwlc 972,669 source: sri lanka redd+ readiness preparation proposal, 2012 compatibility of sri lanka’s protected areas with nature-based tourism national reserves and sanctuaries are the two major categories of pas managed by the dwlc. national reserves include national parks, strict natural reserves, nature reserves, jungle corridors and marine reserves. over 450,000 ha of land are protected under national reserves of which, nearly 75% are nps (dwlc, 2012). strict nature reserves (snrs) are highly protected landscapes. only research and educational activities are allowed in snrs with the permission of the director general, dwlc. hakgala, yala and ritigal are the three snrs under sri lanka‟s pa network. nature reserves (nrs) are also similar to snrs in many ways. public entry is restricted except for research and education. however, traditional senevirathna & perera /journal of tropical forestry and environment vol. 3, no. 02 (2013) 1-10 3 human activities are allowed in nrs. although recreation or wildlife observation is not allowed in snrs and nrs by mandate, such venues have provisions for research and education under permission. hence snrs and nrs are compatible only with research/education oriented hardcore ecotourism activities. nps are areas established to ensure the maximum protection for wildlife and their habitats while allowing opportunities for the public to observe and study wildlife. there are 22 nps in sri lanka‟s pa network (dwlc, 2012). recreational and tourism opportunities is an important dimension in establishing nps as it generates the public interest while ensuring the economic viability of the establishment (suntikul et al., 2010). sri lanka‟s nps allow wildlife viewing/observation by mandate (fauna and flora protection ordinance, 1938). when considered their magnitude and diverse recreational opportunities, nps are highly compatible with both hard and soft ecotourism activities. in addition, nps often contains monuments of cultural and religious importance and therefore can accommodate cultural tourism activities as well. at present, sri lanka‟s nps are increasingly becoming prime tourism destinations for both international and domestic tourists. according to the 2011 annual statistical reports of the tourism development authority in sri lanka, the revenue received from the nps increased by rs 79,764,105.51 from 2010 to 2011. total visitor arrivals to national parks increased to 836,634 from 630,463 from 2010 to 2011. comparative to 2010 foreign tourist arrivals to nps, year 2011 showed an improvement of 55,338 visitors, while local visitor arrivals increased by 150,833 (table 2 and figure 1). table error! no text of specified style in document.: visitor arrivals volume and revenue to national parks 2011 national park foreign tickets local tickets total no. of visitors total revenue (rs.) no. of visitors revenue (rs.) no. of visitors revenue in (rs.) yala 98,583 154,310,770.10 216,666 12,453,959.00 315,249 166,764,729.10 horton plains 29,854 50,103,251.89 166,818 8,971,550.00 196,672 59,074,801.89 udawalawa 19,901 33,531,189.50 57,024 3,252,161.00 76,925 36,783,350,50 minneriya 23,220 38,342,350.00 36,449 2,120,070.00 59,669 40,462,420.00 hikkaduwa 5,958 170,415.00 46,011 216,275.00 51,969 386,690.00 pigeon island 4,185 4,456,160.00 31,035 1,190,610.00 35,220 5,646,770.00 wilpattu 2,322 3,881,279.00 22,972 1,309,710.00 25,294 5,190,989.00 wasgamuwa 367 403,170.00 18,732 697,230.00 19,099 1,100.400.00 kumana 820 906,725.00 16,277 731,640.00 17,097 1,638,365.00 kaudulla 8,331 9,458,461.00 7,374 292,480.00 15,705 9,750,941.00 bundala 4,780 5,314,700.00 6,616 256,830.00 11,396 5,571,530.00 horagolla 4 4,400.00 4,895 190,290.00 4,899 194,690.00 lunugamwehera 27 29,826.00 2,703 99,880.00 2,730 129,706.00 gal oya 118 23,760.00 1,580 36,180.00 1,698 59,940.00 angammedilla 0 1,483 52,590.00 1,483 52,590.00 galwaysland 39 42,000.00 1,182 46,362.00 1,221 88,362.00 lahugala 25 28,000.00 172 6,230.00 197 34,230.00 maduru oya 2 2,250.00 109 4,824.00 111 7,074.00 total 198,536 301,008,707.49 638,098 31,928,871.00 836,634 332,937,578.49 sanctuaries on the other hand require no permission or fee to enter. sanctuaries allow human activities while protecting the natural environment. both state and private lands can be declared as senevirathna & perera /journal of tropical forestry and environment vol. 3, no. 02 (2013) 1-10 4 0 50,000 100,000 150,000 200,000 250,000 300,000 350,000 y a la n p h o rt o n p la in n p u d a w a la w a n p m in n e ri ya n p h ik k a d u w a n p p ig e o n i sl a n d n p w il p a tt u n p w a sg a m u w a n p k u m a n a n p k a u d u ll a n p b u n d a la n p t o ta l v is it o r a rr iv a ls national park 2010 2011 sanctuaries. hence, sanctuaries are also compatible with nature-based tourism models such as ecotourism. however, due to their nature of establishment, wildlife viewing oppertunities are comparatively limited. in addition, significant number of forest reserves and proposed reserves are under the management of fd. hurulu, kanneliya-dediyagala-nakiyadeniya (kdn) and sinharaja are unesco man and biosphere reserves managed by the fd while sinharaja and central highlands/knuckles range of forests have been designated as world heritage sites. these pa categories under fd are highly compatible with nature-based tourism as they allow research, education, and recreation. figure 1: total visitor arrivals to national parks 2010-2011 althogu it is evident that nature-based tourism in protected areas generate much-needd funds for conservation and development, there are substantial difference between revenues generated at different nps in sri lanka. for instance, revenue at yala np in 2010 was rs. 166,764,729.10 compared to maduru oya np‟s rs. 7,074.00 (stda, 2011). apart from unique recreational opportunities/attractions available at each np, herath et al. (1997) largely attribute this scenario to the lack of awareness among visitors and tour operators regarding the natural diversity and recreational opportunities in sri lanka‟s pas. previous studies elsewhere further point out narrow wildlife viewing preferences of visitors as a main cause of higher visitor pressure in certain pas (kerley et al., 2003; prideaux, 2006; duffiled et al., 2006). for example, an individual with narrow preference of viewing elephants would travel to minneriya np because of the destination‟s overall popularity, despite having several pas in the same region with similar wildlife observing opportunities. the down-side of this scenario is the increased visitor pressure at few popular nps, while nps with low levels of visitation facing the risk of receiving fewer funds for park maintenance and conservation efforts. heavy visitor arrivals to nps are known to cause negative impacts such as interruptions to the behavior of wildlife including habituation, littering, damages to vegetation and increased cases of visitor non-conformities with environmental standards and park policy (herath et al., 1997). in addition, limited perceptions of wildlife viewing can lead to the devaluation of biodiversity in a particular protected area (kerley et al., 2003), and this in turn can lead to negligence of valuable biological resources for conservation by state agencies. therefore, identifying wildlife viewing preferences of visitors has wider applications in visitor management at pas. senevirathna & perera /journal of tropical forestry and environment vol. 3, no. 02 (2013) 1-10 5 3. the case study to gain a preliminary understanding of wildlife viewing preferences of visitors to nps in sri lanka, we conducted a visitor survey at minneriya np located in the north central province of sri lanka. minneriya np was selected as it is one of the top-five highly visited nps in the country. a structured questionnaire was administered via face-to-face interviews, using a systematic sampling method with every one-in-third visitor being intercepted at the park exit to administer the questionnaire. data collection was done from april to august, 2012, predominantly on weekends where higher visitor traffic was anticipated. only visitors over 18 years of age were interviewed. a main objective of this survey was to identify different visitor segments or nature-based tourism market segments based on wildlife viewing preferences. in order to assess the relationships of wild life viewing preferences and key biodiversity elements of np with socio-demographic and trip characteristics of visitors, the multivariate logistic regression method was used. we developed two separate models using wild life viewing preferences and importance of key biodiversity elements of the park as dependent variables. accordingly, we attempted to describe different visitor segments based on wildlife viewing preferences using their demographic characteristics. a total of 735 individuals participated in the survey, and there were 701 usable questionnaires. this included 682 domestic respondents and 19 foreign respondents. due to the low number of foreign respondents, they were excluded from further analysis. general respondent socio-demographic characteristics are summarized in table 3. of those who participated in the survey, 30.1% were first-time visitors to a np in sri lanka. majority of the respondents (62.2%) have visited nps in one to five previous occasions. only 7.8% of the respondents have visited a np more than five occasions within the last five years. table 3: general respondent socio-demographic profile – domestic visitors socio-demographic variable frequency percentage gender (n = 701) male 397 56.6 female 304 43.3 age ( n = 682) 18-25 142 20.2 26-45 461 65.7 above 45 98 14.0 education ( n = 682) up to o/l or below 122 17.4 up to a/l or a/l with professional qualifications 405 57.8 undergraduate (ug) education & above 174 24.8 income (n=597) ≤rs. 30,000 350 57.1 rs. 30,001 to rs 75,000 211 34.4 above rs. 75,000 36 5.9 respondent preferences for key biodiversity elements respondents were asked to rank the importance of some key biodiversity elements of the np that influenced them to choose minneriya np as the destination for travelling (on a 1 to 5 likert scale where senevirathna & perera /journal of tropical forestry and environment vol. 3, no. 02 (2013) 1-10 6 4.3 4.37 4.41 4.16 4.49 1.00 2.00 3.00 4.00 5.00 attractive scenery bird diversity mammal diversity floral diversity elephant herds m e a n v a lu e reserve characteristics 4.55 4.48 4.36 4.25 4.27 4.50 1.00 2.00 3.00 4.00 5.00 elephant leopard bear aquatic birds terrestrial birds herbivores m e a n v a lu e animal categories 1= least important and 5= highly important). most respondents ranked “elephant herds” as the most important biodiversity element followed by mammal diversity, bird diversity and attractive scenery (figure 2). when asked about their desire to observe different components of wildlife during the trip, most respondents gave priority to watching elephants, followed by herbivores (other than elephants), leopards, and bears (figure 3). majority of the respondents were interested in observing elephants in the wild (90.5%), while observing aquatic birds was least preferred (54.8%). the relationship between key biodiversity elements and the socio-demographic variables to understand the relationships between key biodiversity elements of the park and sociodemographic variables, scores given by respondents to key biodiversity elements were categorized as „indifferent‟ (scores 1 to 3) or „interested‟ (scores 4 and 5), and was analyzed relative to respondent age, education, and number of visits to nps in the last five years. table 4 summarizes the results of logistic regression models developed for each reserve characteristic. it indicates the odds of visitor in each category being interested in each reserve characteristic, relative to the reference category. underlined values represent statistically significant relationships (p<0.05). statistically non-significant variables are also reported for illustrative purposes. table 4: relationship between reserve characteristics and the socio demographic characteristics of the respondents underlined odds ratios are the significant ones p<0.05 b reference category (fixed) in this case study, we interpreted the results using odds ratios. for example, attractive sceneries seem to be a more important biodiversity element for respondents with higher levels of education i.e. comparative to a visitor with graduate education, “attractive sceneries” are 0.831 times less important for reserve characteristics model previous visits age education 18-25 26-45 above 45 up to o/l or <o/l up to a/l or a/l-pq ug or higher attractive scenery x 2 =70.056 ; p<0.001 0.025 .281 -0.093 0 b -2.413 -0.831 0 b bird diversity x 2 = 55.476 ; p<0.001 0.174 .012 0.150 0 b -1.026 0.110 0 b floral diversity x 2 = 62.932 ; p<0.001 -0.015 -.032 -0.069 0 b -1.729 -0.233 0 b mammal diversity x 2 = 20.004 ; p=0.01 0.071 .042 0.136 0 b -0.773 -0.139 0 b elephant herds x 2 = 28.290 ; p<0.001 -0.083 -.325 -0.261 0 b 0.199 -0.017 0 b figure 2: mean values for responses of essentiality of key biodiversity elements figure 3: mean values for viewing preferences of different animal categories senevirathna & perera /journal of tropical forestry and environment vol. 3, no. 02 (2013) 1-10 7 a visitor with an education level of “up to a/l or a/l and professional qualified”. for a visitor with an education of “up to o/l”, the same biodiversity element is 2.413 times less important in comparison to the reference group. essentiality of the bird diversity was influenced by variables “number of visits” and education. this indicates that experienced visitors with higher levels of education are more interested in bird diversity. bird diversity was 1.026 times less important for a visitor of least educated group in comparison to highest educated group. education level was the only factor that significantly affected preference for floral diversity. floral diversity was 1.729 times less important for a visitor of least educated group in comparison to highest educated group. similar observations were made for the key biodiversity element “mammal diversity”. the biodiversity element “elephant herds” was specially included as it is a site specific attribute to minneriya np. only the number of visits was significant in the model. this indicated that novice visitors are more interested in observing elephant herds. the relationship between wildlife viewing preferences and the socio-demographic variables respondent scores for preference to observe different components of wildlife were categorized into „indifferent‟ (scores 1 to 3) and „interested‟ (scores 4 and 5), and were analyzed relative to respondent age, education, and number of visits to nps in the last five years (table 5). results indicate that experienced visitors with higher level of education tend to prefer watching aquatic birds as well as terrestrial birds. for instance, least educated individual is 1.008 times less likely to prefer the wildlife component “aquatic birds”. rarely observable mammals such as bears and leopards were mostly preferred by individuals who are frequent visitors to the nps. both age and education were non-significant for respondent preference to observe elephants. the variable “number of visits” was also negatively related, indicating that first-time visitors or less experienced wildlife enthusiasts prefer charismatic species such as elephants. similar trend was observed for the preference for other larger herbivores such as deer, buffalo and sambar deer. table 5: relationship between wildlife viewing preferences and the socio demographic characteristics of the respondents wildlife preferences model previous visits age education 18-25 26-45 above 45 up to o/l or <o/l up to a/l or a/l-pq ug or higher aquatic birds x 2 =116.972 ; p<0.001 0.433 -0.029 -0.359 0 b -1.008 -0.129 0 b bears x 2 = 84.288 ; p<0.001 0.321 -0.422 -0.242 0 b -0.727 -0.058 0 b elephants x 2 = 20.709 ; p<0.01 -0.094 -0.539 -0.170 0 b -0.616 -0.139 0 b herbivorous x 2 = 18.990 ; p<0.01 -0.056 -0.120 0.094 0 b -0.560 -0.422 0 b leopards x 2 = 87.147 ; p<0.001 0.442 -0.497 -0.566 0 b -0.648 0.032 0 b terrestrial birds x 2 = 28.290 ; p<0.001 0.417 0.312 0.172 0 b -1.116 -0.211 0 b underlined odds ratios are the significant ones p<0.05 b reference category (fixed) 4. impetus for visitor management analysis of visitor preferences found that visitor preferences differ according to their previous experiences as well as demographic characteristics. logistic regression models developed for “importance of reserve characteristics” indicate that level of education is an important determinant in an individual‟s tendency to appreciate alternative natural components of a protected landscape. in general, importance of less popular components such as floral diversity, bird diversity and attractive landscapes were substantially influenced by an individual‟s level of education. senevirathna & perera /journal of tropical forestry and environment vol. 3, no. 02 (2013) 1-10 8 this case-study further indicates that most of the visitors preferred charismatic fauna such as elephants, leopards, and bears. even though charismatic faunal species are important in attracting new visitors to nps, subordinate features of nps also play a key role in sustaining visitor numbers by attracting more experienced visitors. when considered the visitor arrivals to the minneriya np in 2011, the total was 59,669 visitors. among those visitors 61% were local visitors. from 2009 to 2011, total visitor arrivals to nps in sri lanka has improved by 31.6%, while local visitor arrivals has increased by 27.3% (stda, 2009; stda, 2010; stda, 2011). this increase of visitor arrivals indicates the growth of unexperienced or first-time visitor arrivals to nps. this signifises the increase in demand for viewing charismatic fauna. however, results of this study also indicate a gradual increase in experienced visitors. as a result, the demand for viewing alternative component of biodiversity within nps could be anticipated to increase. recent studies also indicate that nature-based tourism and ecotourism markets in sri lanka has become more heterogeneous (perera et al., 2012; perera and vlosky, 2013). this is likely to provide new opportunities to promote nps or pas which are less-known for charismatic species, but contain more subordinate features of biodiversity. statistics show that few nps in sri lanka receive higher visitor arrivals while most nps having relatively low visitations. for instance, only yala and horton plains nps had visitor arrivals more than 100,000 in year 2011 (sltda, 2011). in the case of minneriya np, higher visitor arrivals can be observed during the period of august to october especially to witness the “elephant gathering”, and the destination is largely marketed as a venue for observing elephants. opening nps for visitor levels above carrying capacity can have negative impacts such as lack of visitor satisfaction and disturbances and altered natural behaviors of wildlife. as suggested by herath et al. (1997), diversification of visitation is an option available to administrators of nps to reduce the pressure of overcrowding in few nps. marketing a diversity of tourist products in line with the diverse viewing preferences of visitors to protected areas may prevent over-crowding of popular nature-based tourism destinations. furthermore, based on wildlife viewing preferences, strategies could be formulated to prevent less-desired types of visitors entering into more sensitive areas of nps, and alternatively providing them with sufficient recreational opportunities in already disturbed sites within nps. visitor experience (determined by number of previous visits to nps) has been found to be a key visitor characteristic that drives the demand for nature-based tourism or ecotourism (perera and vlosky, 2013). results of this case study further indicate that there is a considerable demand for viewing subordinate features of nps, especially from highly educated and frequent visitors to nps. this opens up new opportunities to introduce sustainable forms of tourism such as ecotourism in nps and other pas. for instance, specialized programs or tourism opportunities focused on bird identification, bird biology, and bird watching shall be introduced for experienced birders. similar programs may be introduced for other components of biodiversity as well. on the other hand, less sophisticated programs/tours aimed at providing a fundamental knowledge on nature and ecosystems (introduction to the park and its flora and fauna, birding, and other sites of importance) shall be introduced for novice visitors. the study also highlights the necessity to adopt an integrated regional approach for visitor management at pas with the involvement of public and private sectors. for instance, minneriya np is known as a destination ideal for elephant watching. minneriya is located in close proximity to three more wild life parks of sri lanka: kaudulla np to the north, wasgamuwa np to the south and flood plains np to the north-east. these venues are also ideal for elephant watching except during the peak dry period. by adopting an integrated regional visitor management strategy, the visitor pressure at one highly popular np could be lessened by diverting portion of the visitors to other venues. however, this requires appropriate destination promotion and marketing strategies to popularize alternative venues as ideal nature tour destinations. alternative destinations should be identified and promoted to divert visitors interested in subordinate features of nps, as popular nps are already receiving enough traffic with visitors interested in observing charismatic species. senevirathna & perera /journal of tropical forestry and environment vol. 3, no. 02 (2013) 1-10 9 sri lanka‟s pas include diverse ecosystems and the recreational opportunities available in pas differ substantially from one to another. this case-study was restricted to a single highly-visited np in sri lanka and only domestic visitors were considered in describing visitor segments. hence, the present study is not without its limitations. however, visitor segments identified by the present study are comparable with nature-based tourist segments described in previous studies (perera et al., 2012). nonetheless, this case study provide useful insights to wildlife viewing preferences of visitors to nps and forms a foundation for future studies on identifying biodiversity observation preferences of visitors to pas in sri lanka, and impetus for visitor management. references department of wildlife conservation. 2012. protected areas in sri lanka. retrieved 2013, from department of wildlife conservation: http://www.dwc.gov.lk duffield, j., neher, c., and patterson, d. 2006. wolves and people in yellowstone: impacts on the regional economy. missoula: university of montana. fauna and flora protection ordinance. 1938. retrieved 2013, from commonlii: www.commonlii.org/lk/legis/consol_act/fafp567290.pdf herath, h., m, b., c., sivakumar, m., and steele, p. 1997. a strategy for nature tourism management: review of the environmental and economic benefits of nature tourism and measures to increase these benefits. united states agency for international development (usaid) and government of sri lanka. icra lanka. (2011). travel and tourism: industry report on sri lanka. colombo: imacs and icra. kerley, g. i., geach, b. g., and vial, c. 2003. jumbos or bust: do tourists‟ perceptions lead to an underappreciation of biodiversity? south african journal of wildlife research (33), pp.13–21. lonely planet‟s best in travel: top 10 countries for 2012. 2012. retrieved 2012, from lonelyplanet: www.lonelyplanet.com/europe/travel-tips-and-articles/76856 ministry of economic development. 2011. tourism development strategy 2011-2016. colombo: sri lanka. ministry of environment and natural resources. 2002. state of the environment in sri lanka. colombo: ministry of environment and natural resources, sri lanka. perera, p., and vlosky r. p. 2013. how previous visits shape trip quality, perceived value, satisfaction, and future behavioral intentions: the case of forest-based ecotourism in sri lanka. international journal of sport management, recreation and tourism. vol. 11 (a) pp. 1-24. perera, p., vlosky r., and wahala s. 2012. motivational and behavioral profiling of visitors to forestbased attractions in sri lanka. asia pacific journal of tourism research. 7 (4), pp. 451-467 prideaux, b. 2006. wildlife tourism in tropical north queensland:an overview of visitor preferences for wildlife experiences. national library of australia. sri lanka the 2nd best tourist destinationnational geographic channel. (2010, march 18). retrieved 2012, from aitkenspenceplc: http://aitkenspenceplc.wordpress.com/2010/03/22/sri-lanka-the-2ndbest-tourist-destination-%e2%80%93-national-geographic-channel/ sri lanka tourism development authority. 2010. annual statistical report of sri lanka tourism-2010. colombo, sri lanka. sri lanka tourism development authority. 2009. annual statistical report-2009. colombo, sri lanka. sri lanka tourism development authority. 2011. annual statistical report of sri lanka tourism2011. colombo, sri lanka. http://www.dwc.gov.lk/ http://www.commonlii.org/lk/legis/consol_act/fafp567290.pdf http://www.lonelyplanet.com/europe/travel-tips-and-articles/76856 http://aitkenspenceplc.wordpress.com/2010/03/22/sri-lanka-the-2nd-best-tourist-destination-%e2%80%93-national-geographic-channel/ http://aitkenspenceplc.wordpress.com/2010/03/22/sri-lanka-the-2nd-best-tourist-destination-%e2%80%93-national-geographic-channel/ senevirathna & perera /journal of tropical forestry and environment vol. 3, no. 02 (2013) 1-10 10 suntikul, w., richard, b., and david, a. 2010. implications of political change on national park operations: doi moi and tourism to vietnam's national parks. journal of ecotourism, 9 (3), pp. 201218. the 31 places to go in 2010. retrieved 2012, from new york times www.nytimes.com/2010/01/10/travel/10places.html:?pagewanted=all un-redd programme. (2012, february). sri lanka redd+ readiness preparation proposal. retrieved july 8, 2012, from forest carbon partnership: www.forestcarbonpartnership.org/.../feb2012/sri%20lanka%20r--pp weaver. d. 2001. ecotourism. milton: john willey & sons. australia. wijesinghe, l., c, a, 2003. forestry in sri lanka a voyage through time. tropical agricultural research and extension, pp. 14-21. microsoft word 7 shermila shermila & wickramasinghe/journal of tropical forestry and environment vol. 3, no. 01 (2013) 55-63 55 composition of mix species foraging flocks of birds in riverstan of montane region, sri lanka w.g.d.d.m. shermila* and s. wikramasinghe department of biological science, rajarata university of sri lanka, mihinthale date received: 21-11-2012 date accepted: 23-02-2013 abstract montane zone mixed-species bird flock system is distinct from that of low-land wet zone of sri lanka, although some species are present in both systems. the present study identified the mixed species flocks of birds in riverstan at knuckles region, sri lanka. monthly transect counts and opportunistic observations were made between january and may, 2012. a total of 78 flocks and 27 bird species were encountered at riverstan during the study period. the flock size varied between 2 to 13 species and 4 to 58 individuals. the mean number of species per flock was 6.03 ± 2.25 and the mean number of individuals in a flock was 18.41±9.87. the flock size was positively correlated with the number of species present (r = 0.756, p <0.05). grey-headed canary flycatcher was the most abundant species (mean 2.68±1.02 birds per flocks) while sri lanka white-eye was the most frequent species (mean 5.69±3.92 birds per flocks). grey-headed canary flycatcher and sri lanka scimitar-babbler were the nuclear species in riverstan. the leading species were sri lanka white-eye and sri lanka yellow-eared bulbul. different bird species used different heights within flocks. keywords: mixed-species flock, nuclear species, abundance, foraging flocks 1. introduction mixed-species flocks (msf) are an important form of the social organization of birds throughout the world, particularly in the forested tropics (thiollay, 1999). the mixed-species flocks were characteristic of all forest edge habitats, and their composition varies with the elevation and habitat. nuclear species mainly differ with the elevation and habitat in the northern flank of the knuckles range (sriyani et al., 2005). montane zone flock system is distinct from that of low land wet zone of sri lanka, although some species are present in both systems. the studies on flocking behaviour in sri lanka have been predominantly conducted in the low land wet zone forests. hence, relatively little information is available on flocking behaviour in other habitat types in sri lanka and it is important to have a working knowledge of the structure, dynamics and special organization of msf to assess the status of msf to formulate suitable conservation strategies for msf. therefore, the present study was carried out to identify the flock composition, vertical distribution pattern, habitat preference of the flocking species in msf at riverstan of montane region. *correspondence: dayani_weragoda@yahoo.com tel: +94 774401636 issn 2235-9370 print / issn 2235-9362 online ©2013 university of sri jayewardenepura shermila & wickramasinghe /journal of tropical forestry and environment vol. 3, no. 01 (2013) 55-66 56 2. study area the study was conducted riverstan montane region (figure 1.) (7°32' n, 80°44' w, 950m) located in the central province of sri lanka. the study area is 6 km 2 in area and encompasses altitudes ranging 900 m to 1100 m (herath and priyantha, 2003). the vegetation is predominantly sub-montane forests with wet phase at higher altitude and dry phase in lower altitude. this forest retains a multilayered and the higher of the forest is approximately 15 m from ground to top canopy. the study area consisted of secondary forest; understory vegetation is generally dense cover with cardamom cultivation. figure 1: map of the study site 3. methodology 3.1. data collection mixed-species flocks were sampled on the established line transects and opportunistically along pre-determined transect daily two weeks per month starting from january to may 2012. a distance of 200m maintain between two flocks during the counting to avoid the repeated counts. while walking along transects the mixed-species flocks were observed and the gps coordinates at these points were recorded. as soon as a mixed species flock was met, the vegetation was scanned thoroughly from the canopy layer down to the forest understory so as to identify all flock participants. when encountered on transects, for each mixed-species flock, species composition, as well as the cluster size, detection azimuth and detection distance for each species cluster in the mixed-species flock were recorded. these data were incorporated during species abundance estimation. during opportunistic sampling, the species composition of the mixed-species flock and the group size of each participating species were recorded. for the species observed, classified them according to their occurrence in msf as: core (nuclear, leader) (present in 40 % or more of the mfss), regular (common) (more than 11%), and occasional (rare) (< 11 %) following machado (1999). shermila & wickramasinghe/journal of tropical forestry and environment vol. 3, no. 01 (2013) 55-63 57 3.2. data analysis the spearman correlation test was done to determine the correlation between number of species and number of individuals in a flock at riverstan. multivariate analysis was used to plot the tree-cluster dendrogram to determine the degree of association between height of the flock species and feeding categories of the different species in the flocks at two sites. this is derived from a matrix based on the degree of structural overlap for the species (bell, 1981). this shows which species are most closely associated with each other in different habitats within the site. the computer program statistic version 16 was used for the plotting of the dendrogram. 4. results 4.1. flock composition a total of 78 flocks and 27 flocking species were encountered at riverstan during the study period (table 1). out of 27 flocking species 19 residents, 7 endemics and 1 migrant species were observed in the study site. one mammal, the jungle squirrel (funambulus sublineatus obscures) was common in all flocks. most of the flocks (19.22%) at riverstan consisted of six species. mean species richness (derived from a raw count of the number of species) was 6.03 species (range from 2 to 13 species. sd = 2.25). the mean number of individuals in these flocks was 18.41 (range from 4 to 58, sd = 9.87). over 50% of the flocks had 11 to 20 individuals while flocks with 41 to 50 individuals were few (1.28%) (table2). grey-headed canary flycatcher (culicicapa ceylonensis) was the most frequent species (mean 2.68±1.02 birds per flocks) encountered in 63 flocks while sri lanka white-eye (zosterops ceylonensis) was the most abundant species (mean 5.69±3.92 birds per flocks) encountered with 269 individuals and 52 flocks. the flock size was positively correlated with the number of species present (r = 0.756, p = 0.00) (figure 2.) figure 2: correlation between number of species and flock size at riverstan shermila & wickramasinghe /journal of tropical forestry and environment vol. 3, no. 01 (2013) 55-66 58 table 1: the number of flocking species detected in 78 flocks in riverstan (n = 78) name of the species category mean of the birds frequency in flocks relative abundance 1.oriental white-eye br (owe) zosterops palpebrosa r 6.00 ± 6.96 17.95 5.87 2.sri lanka white eye e (slwe) zosterops ceylonensis l 5.69 ± 3.92 66.67 20.67 3.velvetfronted nuthatch br (vfnh) sitta frontalis r 3.87 ± 1.99 48.72 10.27 4.sri lanka yelloweared bulbul e (yebb) pycnonotus penicillatus l 3.81 ± 2.85 53.85 11.17 5.jerdon's leafbird br (jlb) chloropsis aurifrons o 3.50 ± 2.08 5.13 0.98 6.black bulbul br (bbb) hypsipetes leucocephalus humii r 3.13 ± 1.12 30.77 5.24 7 .purple –rumped sunbird br (prsb) nectarinia zeylonica zeylonica o 3.00 ± 2.83 2.56 0.42 8. sri lanka scimittar babbler e (sb) pomatorhinus horsfieldii n 2.86 ± 0.98 47.44 7.40 9.dark fronted babbler br (dfb) rhopocichla atriceps o 2.78±1.20 9.54 1.75 10.greyheaded canary flycatcher br (ghcfc) culicicapa ceylonensis n 2.68 ± 1.03 80.77 11.80 11.flame minivet br (fm) pericrocotus cinnamomeus r 2.55 ± 1.04 14.10 1.96 12.brown-capped babbler e (bcbb) pellorneum fuscocapillum o 2.33 ± 0.58 3.85 0.49 13.tawny-bellied babbler br (tbbb) dumetia hyperythra phillipsi o 2.33 ± 0.58 3.85 0.49 14.bar-winged flycatcher-shrike br (bwfcs) hemipes picatus leggei r 2.29 ±0.69 30.77 3.84 15.small minivet br (sm) pericrocotus cinnamomeus o 2.25 ± 0.50 5.13 0.63 16.grate tit br (gt) parus major r 2.15 ± 0.71 50.00 5.87 17.green tree warble m (gtw) phylloscopus trochiloides viridanus o 2.14 ± 0.38 8.97 1.05 18.dull-blue flycatcher e (dbfc) eumyias sordid r 2.11 ± 0.38 11.54 1.33 19.whitebrowed bulbul br (wbbb) pycnonotus luteolus insulae o 2.00 ± 0.38 1.28 0.14 20.yellowfronted barbet br (yfb) megalaima flavifrons r 1.94 ± 0.38 23.08 2.44 21.whitebellied drongo br (wbd) dicrurus caerulescenns leucopygialis o 1.67 ± 1.15 3.85 0.35 22.long-billed sunbird br (lbsb) nectarinia lotenia lotenia r 1.53 ± 0.52 19.23 1.61 23.common iora br (ci) aegithina tiphia o 1.50 ± 1.07 10.00 0.84 24.jungle squirre (js) funambulus sublineatus obscures r 1.35 ± 0.49 21.79 1.61 25.malabar trogon br (mt) harpactes fasciatus r 1.22 ± 0.44 11.54 0.77 26.black – napped monarch br (bnm ) hypothymis azurea ceylonensis r 1.18 ± 0.40 14.10 0.91 27.sri lanka spot winged thrush e (slswt) zoothera spilopter o 1.00 ± 0.00 2.56 0.14 br breeding resident, e endemic, m – migrant shermila & wickramasinghe/journal of tropical forestry and environment vol. 3, no. 01 (2013) 55-63 59 nnuclear, llead, rregular, ooccasiona table 2: percentages of number of species per flocks and number of individuals per flock at riverstan 4.2 flock organization flocking bird species were categorized as nuclear, lead, regular, and occasional (table 1). out of the 27 species, 4 species were core participant, 11 species were regular attendants and 11 species were irregular attendants (figure 3). grey-headed canary flycatcher and sri lanka scimitar babbler were the nuclear species in riverstan and they contributed to form flocks. among these two species, grey-headed canary flycatcher was the most prominent nuclear species at riverstan. sri lanka scimitar babbler formed small mixed-species foraging flocks. they formed flocks in the absence of the grey headed canary flycatcher. the leading species were far ahead of the followers and they were sri lanka whiteeye and sri lanka yellow-eared bulbul. it was observed that more than 60% flocks were lead by sri lanka white eye. black bulbul contributed to give alarm calls in the flock. figure 3: number of species in flock participation according to the role 4.3 niches occupancy of flocking species bird species in the flock had different foraging niches. the degree of association between height of the flock species and feeding categories of different species in the flocks were shown in figure 5. structural overlap values between several species were high and these were grouped together. flocks no. of species per flocks 2 3 4 5 6 7 8 9 10 11 12 13 riverstan % of flocks 2.56 8.97 15.38 16.66 19.22 15.38 8.97 6.41 1.28 2.56 1.28 1.2 8 mean number of species per flock 6.03± 2.25 no of individuals per flocks <10 11-20 21-30 31-40 41-50 >50 riverstan % of flocks 16.6 53.84 19.23 6.41 1.28 2.56 mean number of individuals per flock 18.41± 9.87 shermila & wickramasinghe /journal of tropical forestry and environment vol. 3, no. 01 (2013) 55-66 60 consisted of two major groups (a and b) in foraging flocks. group a had bird species which used canopy and sub-canopy as feeding niche. this group was divided mainly into two sub groups. ten bird species were clustered under group i and they fed on upper layer of the vegetation (canopy and upper sub canopy). group i was divided into two clusters. among these two clusters black bulbul, yellowfronted barbet, flame minivet, jerdon's leafbird, small minivet were under one cluster and they usually used canopy as foraging level. the other cluster under group i, consisted of bar-winged flycatcher-shrike, oriental white-eye, sri lanka white eye, common iora, sri lanka yellow-eared bulbul and these bird species forage on upper level of sub canopy. under this category structural overlap value of sri lanka yellow-eared bulbul was less because they fed on selected tree species in between sub canopy to under story. group ii consisted of ten bird species. under this group the structural overlap among greyheaded canary flycatcher, velvetfronted nuthatch, and green tree warbler was higher because they feed on canopy to understory. in addition to that structural overlap was observed between grate tit and dull-blue flycatcher. long-billed sunbird had less structural overlap among group ii bird species because it was used a different foraging height. group b consisted of five flocking species. these species used understory to ground level as a feeding height. dark fronted babbler and sri lanka scimittar babbler were clustered together under group b because they use ground to sub canopy as a feeding niche. brown-capped babbler, sri lanka spot winged thrush and tawny-bellied babbler were clustered under one group and structural overlap among these birds were higher because they fed on ground and understory. the highest percentage of flocking birds used the sub canopy layer as their foraging level. according to the feeding guild of birds, foliage and flower gleaners and salliers represented high percentage within flocks (figure 4). this is because of insectivores were high in flocks. figure 4: feeding guilds of flocking species at riverstan 5. discussion montane zone flock system is distinct from that of the low land wet zone of sri lanka, although same species are represented in both systems (kotagama and goodale, 2004). singharaja flocks are always included orange-billed babbler (turdoides rufecens), greater racket-tailed drongo (dicrurus paradiseus) but riverstan flocks always contain greyheaded canary flycatcher, sri lanka white eye, sri lanka yellow-eared bulbul and sri lanka scimitar babbler. shermila & wickramasinghe/journal of tropical forestry and environment vol. 3, no. 01 (2013) 55-63 61 figure 5: dendrogram of relationship of foraging height of species in riverstan flocks among these birds, greyheaded canary flycatcher and sri lanka scimitar babbler contributed to form riverstan flocks. the movement, especially vocalizations made other birds easy to follow them. grey-headed canary flycatcher was the most prominent nuclear species at riverstan and it formed 310 birds. sri lanka scimitar babbler form small mixed-species foraging flocks and they form flocks when gray headed canary flycatcher is absent. black bulbul and jungle squirrel give alarm calls. the relative configurations of territories of flock participants have a major impact on flock membership and stability. as a flock moves through its range, species join and leave the group within the constraints of their own home range (powell, 1985). dark fronted babbler was a territorial bird and they joined with the flock only in their territory. sri lanka spot winged thrush (zoothera spiloptera) joined to flocks in law frequency (2.86) and moved few distance with the flocks. the flock size was positively correlated with the number of species present at riverstan. according to powell (1985), the structure and the individual composition of mixed flocks are generally highly stable. flocks are composed primarily of one pair sometimes with young of each species to reduce predation as well as interspecies competition. therefore, flock size is highly positively correlated with the number of species present. the cluster results clearly showed that the difference in utilization of vertical strata is an important factor contributing to niche differentiation within the study area. the foraging assemblage of mixed feeders, insectivores reflect the availability of food resources in different strata. black bulbul, yellowfronted barbet, jerdon's leafbird, sri lanka hanging parakeet were clustered under same main cluster. because they mainly fed on fruits and insects which were available in canopy level. this is generally considered to have largely overlapping food niches because they all feed on fruit at the same foraging sites. grimmett (1998) have explained that different species harvest resources from the same species of fruiting tree in different ways, to reduce overlap. overlap in a food niche may also result from specialization on arthropods that are flushed by a flock. greyheaded canary flycatcher, velvet fronted nuthatch, grate tit, common iora fed on insects in the sub canopy. although it is considered that the food niches of these insectivores are overlapping, the degree of overlapping is less than expected due to the difference on feeding methods among them (figure 4.). gray-headed canary flycatcher was aerial shermila & wickramasinghe /journal of tropical forestry and environment vol. 3, no. 01 (2013) 55-66 62 sallies for insects while velvetfronted nuthatch was bark surface gleaners. grate tit and common iora captured insects by gleaning among the branches for insect. insectivore participation in flocks was higher than that of omnivore and nectarivores at both sites. therefore, percentage of salling, foliage and flower gleaning methods were higher than other feeding methods. all flycatchers which participated in flocks were salliers meanwhile black bulbul, black – napped monarch, forest wagtail, malabar trogon showed salling feeding method. grate tit, common iora, jerdon's leafbird, sri lanka white eye, oriental white-eye, sri lanka hanging parakeet, black headed oriole were main foliage and flower gleaners. among them sri lanka white eye and oriental white-eye mostly preferred to feed on insects in the flowers of epiphytes. sri lanka scimittar babbler, velvetfronted nuthatch, white-rumped shama were the bark surface gleaners. sri lanka spot winged thrush, brown-capped babbler was ground scratchers and sunbirds were hoverers. yellowfronted barbet, sri lanka yellow-eared bulbul, showed fruit picking. as shown above, bird species associated with mixed-species foraging bird flocks have different kinds of feeding methods and feeding guilds. these differences among bird species permit more systematic resource harvesting, reduce interspecific aggression, or facilitate reduction of niche overlapping (austin and smith, 1972). mixed-species bird flocking was common phenomena in the knuckles region. riverstan flocks contained 19 residents, 7 endemics, 1 migrant species and threatened species. as an example, sri lanka yellow-eared bulbul (pycnonotus penicillatus) is one of the nearly threatened and endemic species within a flock. most of the endemic flocking bird species had narrow to restricted altitudinal ranges; and were exclusively dependent on primary forest and understory micro-habitats. sri lanka spot winged thrush (zoothera spiloptera) was limited to undisturbed and understory micro-habitats while sri lanka yelloweared bulbul was limited to high altitude. therefore, it is important to conserve their native habitats and conservation actions should be taken to ensure their future stability. some habitats have a high number of species that form mixed species flocks and should be given top priority in conservation decisions. it is important to maintain habitat heterogeneity (e.g., closed canopy cover and high density of trees) as it is critical for the preservation of mixed species flock richness. the nuclear species play an important role within a flock. it is important to have knowledge about those species to take conservation action and conserve them and awareness programs should conduct to increase the interest on mixed species foraging flocks among the people and through this ensure their conservation status. visitor entrance affects the flocking behaviour in many ways. therefore, it is important to limit the visitor entrance where the flocking tendency is high. mixed-species foraging flocks give natural beauty to the nature as well as help to keep the forest ecosystem more stable. therefore, it is important to protect the bird community. 6. conclusion among the 78 flocks 27 flocking species were recorded at riverstan during the study period. two nuclear species contributed to form msf at riverstan such as grey-headed canary flycatcher and sri lanka scimitar babbler while sri lanka white eye and sri lanka yellow-eared bulbul lead flocks. black bulbul and jungle squirrel gave alarm calls in the flock. bird species in the flock used different height rangers when they were feeding and moving. there were some structural overlapping foraging niches among bird species within flocks. but, the structural overlapping was reduced because bird species in same strata used different foraging gilds and foraging techniques. there were positive correlation between the flock size and the number of species present at riverstan (r = 0.756, p = 0.00), this is because to reduce inter-species competition. shermila & wickramasinghe/journal of tropical forestry and environment vol. 3, no. 01 (2013) 55-63 63 there are several threats for mixed-species flocks. visitor entrance, habitat modification, forest fires and illegal logging were major threats which are identified. therefore, conservation action should be taken to conserve msf and ensure their survival. acknowledgement the authors wish to extend their gratitude to prof. s.w. kotagama for the guidance, mr. supun wellappuliarachchi, mr. duminda s.b. disanayake, mr. dilum prebath, miss. chaya sarathchandra for assisting in the field work, and mr. ranjan dissanayake, miss.nethma thabru and miss. s.r.sameranayake for their assistance in statistical analysis of the project. a special thank is also due for mahalakotuwa villagers for their support during the project. references austin, g. t., e. l. smith., 1972. winter foraging ecology of mixed insectivorous bird flocks in oak woodland in southern arizona. condor 74:17-24. bell, h.l., 1981. a bird community of lowland rainforest in new guinea mixed species feeding flocks. emu (82): 143-162 grimmett, r., inskipp, t., inskipp, c., 1998. birds of the indian subcontinent. oxford university press, delhi heart, t.r., priyantha, r, 2003. an illustreted guide to the fern flora of knuckles conservation area sri lanka, rajarata university of sri lanka. isbn: 955-99116-0-0 kotagama, s.w., googale, e., 2004. the composition and the spatial organization of mixed-species flocks in a sri lanka rainforest. forktial 20, 63-70. machado, c.g., 1999. mixed flocks of birds in atlantic rain forest in serra de paranapiacaba, southeastern brazil, revista brasileira de biologia 59(1): 75–85. powell, g. v. n., 1985. sociobiology and adaptive significance of interspecific foraging flocks in the neotropics. ornithol. monogr. 36: 713_732. sriyani, w.m., padmalal, u.k.g.k. and kotagama, s.w., 2005. a study on mixed species birds flocks of sub montane wet evergreen forest in the northern flank of the knuckles region in sri lanka. lyriocephalus, 6 (1-2): 277-284. thiollay, j.-m., 1999. frequency of mixed-species flocking in tropical forest birds and correlates of predation risk: an intertropical comparison. j. avian biol. 30: 282_294. 24 allelopathic potential of rice residues of selected rice varieties (oryza sativa l.) against echinochloa crus-galli a.s. ranagalage, t.s.d. jayakody and d.l. wathugala * department of crop science, faculty of agriculture, university of ruhuna, mapalana, kamburupitiya, sri lanka date received: 05-02-2014 date accepted: 03-07-2014 abstract selection of rice varieties with greater allelopathic potential can be used as a tool in sustainable weed management. exploitation and implementation of this technology in weed management has been considered as ecologically sound, resource conserving and economically viable method. the objective of this study was to assess the allelopathic traits of rice residues of selected rice cultivars (bg 359, ld 365, bg 407, at 401, bg 358, at 362, at 402, bg 450, bg 300, herathbanda and handiran) to suppress barnyard grass (echinochloa crus-galli) seed germination, growth and development which is one of the most destructive weeds in sri lankan paddy ecosystem. completely randomised design was used with three replicates for each cultivar. according to the research findings, significant differences (p≤0.05) were observed among cultivars and amount of residue mixed with sand (2, 4, 6 g of ground residue per 500 g of sand) in terms of barnyard grass plant height, number of leaves, germination and total dry weight. among those measured variables germination and dry matter accumulation of barnyard grass showed significant reduction when increasing amount of rice residues. among different cultivars used ld 365 showed the highest inhibition % for all above measured variables and the lowest was the herathbanda. as an example the inhibition percentages of plant height, seed germination and shoot dry weight of barnyard grass grown in 6 g of ld 365 rice residue mixture were 72.7%, 74.2% and 82.6% respectively. in contrast, residues of rice variety herathbanda caused 36.6%, 37.9% and 40.5% inhibition respectively for above mentioned parameters. when comparing three levels of rice residue mixture suppression ability of barnyard grass seed germination was increased. therefore, it could be suggested that the allelopathic potential of rice residue significantly changes with cultivar and amount of residue incorporated with soil. knowledge of rice allelophathic properties of rice residue will offer several possibilities for ecological management of weeds in paddy fields in sri lanka. keywords: allelopathy, echinocloa crus-galli, inhibition, oryza sativa * correspondence: lakmini077@yahoo.com tel: +94 71826 5218 issn 2235-9370 print/issn 2235-9362 online © university of sri jayewardenepura ranagalage et al. /journal of tropical forestry and environment vol. 4. no 02 (2014) 24-30 25 1. introduction rice is the dietary staple in sri lanka, and is cultivated in almost all parts of the island. in sri lanka, paddy cultivation has been hardly threatened by number of factors and circumstances. out of them severe weed infestation in paddy fields become critical and it adversely affect to the ultimate paddy yield and quality. rice growing areas worldwide are also seriously affected by the presence of several weeds. weeds are plant species that compete with the crop for resources, such as sunlight, space and nutrients. weed control is as old practice as agriculture itself. it is the method of limiting weed infestation so that crops can be grown profitably. therefore, the degree of weed control depends on costs/benefits and the resources available. nowadays, herbicide-based weed management is the most popular method of weed control in rice. although, herbicide use alleviates the weed problem it emerge the unrecoverable and inevitable hazards to the natural environment including flora, fauna and human being. at the present crisis is the any aspect concern in environmental point of view. herbicides cause degradation of water resources, bad effects on human health, reduces biodiversity and ultimate itself coined for development of herbicides resistant species. therefore, shifting to environmentally friendly weed management methods is important. generally, it could be observed that although herbicide use has increased productivity, there are several weed problems that remain unsolved and for which other solutions need to be developed and implemented (labrada, 1996). barnyard grass (echinochloa crus-galli) is one of the greatest yield-limiting weeds in the irrigated rice systems of sri lanka. it is better adapted to grow under dry conditions rather than wet conditions. now most paddy farmers practice direct seeding to minimise cost of production and due to water scarcity paddy fields are not frequently in flooded condition. these practices create good conditions to grow barnyard grass in the paddy field and this weed expect to become greater problem in future (im et al., 1993). at field conditions competition and allelopathy effects cannot be separated. initially plant breeders pay their great attention to uplift competition component rather than allelophathy. however, these emphasise showed little success. allelopathy is defined as the direct or indirect harmful or beneficial effects of one plant on another through the production of chemical compounds that escape into the environment (rice, 1984). chemicals released from plants and imposing allelopathic influences are termed allelochemicals. allelochemicals can be present in several parts of plants including roots, rhizomes, leaves, stems, pollen, seeds and flowers. allelochemicals are released into the environment by root exudation, leaching from aboveground parts and volatilization and/or by decomposition of plant material (rice, 1984; reigosa et al., 1999). this phenomenon could be an alternative weed control method. a number of studies have been conducted to evaluate the allelopathic potential from rice germplasm and number of rice accessions having allopathic potential have been determined in different places (fujii, 1992; garrity et al., 1992; lin et al., 1992; dilday et al., 1994; hassn et al., 1994; chou, 1995, 1999; olofsdotter et al., 1995; chung et al., 1997; ahn and chung, 2000). as an example dilday et al., (1998) identified 412 accessions having allelopathic potential against ducksalad (heteranthera limosa (sw.) willd.), among 12,000 accessions that originated from 31 different countries. these studies showed allelopathic potential is widely present in rice germplasm. further it is assumed that rice allelopathy might be polygenetically controlled because it shows a continuous variation in the germplasm (kim and shin, 2003). moreover, allelopathic potential is often attributed to several 26 inhibitors that are assumed to act in an additive or synergistic way rather than in an isolated way (courtois and olofsdotter, 1998). allelopathic potential of rice residues has also been studied in several places (chung et al., 2001a; 2001b; chung et al., 2002) and several allelochemicals have also been extracted from rice residues. rice (1984) and putnam (1985) reported that allelochemicals are present in virtually all plant parts, i.e., leaves, fruit, stems, rhizomes and roots. according to aldrich (1984), allelochemicals must be concentrated in the leaves, stem or roots rather than in the fruit or flowers. according to the moody (1995) the phytotoxic potential of crop residues could be exploited in handling various weeds in agro-ecosystem successfully. the use of rice germplasm that contains high allelophathic activity, combined with incorporating straw into the soil controlled cyperus irria almost effective as tank mixture of proponil+bentzon (lin et al., 1992). khan and vaishya (1992) reviewed that residues of sarjoo-52 rice incorporated 5-6 cm deep at 5 t/ha reduced the population and biomass of echinochloa colona. chung et al., (2001) evaluated the allelopathic potential of rice in the laboratory, greenhouse and in the field using extracts and residues, and concluded that genetic variation in allelopathic activity exists among cultivars. these results supported previous studies (garrity et al., 1992; dilday et al., 1994; olofsdotter et al., 1995). although allelopathic research has been conducted for several decades very limited knowledge is still available whereas, little information is available on the allelopathic potential of rice cultivar in sri lankan context. therefore, the main purpose of this study was to assess the allelopathic potential of selected rice varieties grown by sri lankan farmers on barnyard grass seed germination and seedling growth. 2. materials and methods eleven rice varieties including 9 sri lankan improved (bg 359, ld 365, bg 407, at 401, bg 358, at 362, at 402, bg 450 and bg 300) and two traditional (herathbanda and handiran) rice cultivars were grown at the field. at the maturity stage plants were harvested. the harvested plants (leaves plus straw) were dried at room temperature. e. crus-galli was also separately grown in the field for seed collection. after maturation e. crus-galli seeds were collected and debris was removed from the seeds by flotation in distilled water, then dried seeds were stored at room temperature until used. the seeds were treated in 100% h2so4 for 10 minutes to break dormancy. these seeds were soaked in water for overnight and then treated with 1:10 (v/v) dilution of topsin for 10 min to prevent fungal contaminations. bioassay was conducted in a greenhouse with an average room temperature. various amount of ground rice residue (2 g (t1), 4 g (t2) and 6 g (t3)) from each cultivar were mixed thoroughly with 500 g of silica sand in each pot. all pots were placed on a petridish to prevent the loss of water-soluble toxic substances (chung and miller, 1995). plastic net was placed in the bottom of each pot to prevent the loss of sand through the holes in the bottom. 100 e. crus-galli seeds prepared as described earlier were placed uniformly about 1 cm deep in each pot after two weeks of residue incorporation. seedling emergence was defined as the coleoptile protrusion through the soil surface and was measured each day for 20 days after seeding. water was added to pretridishes placed to each pot to maintain adequate moisture. all plants were harvested 20 days after planting. all plants from each pot were measured for shoot length, number of leaves and the seedlings were dried at 65 0 c to measure dry weight. control plants were grown in silica sand without residue. the percentage inhibition of each measured parameter was calculated using the following equation (chung et al., 2001). inhibition percentage (%) = [(control-rice cultivar)/control] ×100 (1) ranagalage et al. /journal of tropical forestry and environment vol. 4. no 02 (2014) 24-30 27 the experimental design used for this study was completely randomized design and three replicates were used for each treatment. analysis of variance was performed for all data using a general linear model procedure. 3. results and discussion considerably a large number of researches have been conducted in different countries in order to find out and assesses allelophethic potential of different rice cultivars to achieve sustainable rice farming with minimum use of synthetic herbicides. however, in sri lanka, less information is available on allelopathic potential of rice cultivars and their residues. on the other hand rice residue incorporation in to the paddy fields is very much common practice in sri lanka. therefore, present study aimed to compare abilities of residues of different rice varieties to control barnyard grass. the barnyard grass seed germination, plant height, seedling dry weight and number of leaves affected by the different amount of residues of selected rice varieties are shown in figure 1. data showed marked differences in measured parameters of barnyard grass. the influence of the incorporation of rice residue into sand and the inhibition of growth and development of barnyard grass may be resulted by toxic compounds released from the residues or produced by microorganism activity during residue decomposition. among all measured variables inhibition percentages of seed germination and dry matter accumulation of barnyard grass showed significant reduction when increasing amount of rice residue incorporated to the sand to prepare residue mixture. that means concentration of allelochemicals release when decomposing residues have also been increased with the increase of amount of residues. previous experiments reported the extraction of potential allelochemicals from soils incorporated with rice residue as well as residue aqueous extracts. as an example chung et al. (2001a) has extracted 9 known allelochemicals and their mixtures from rice straw extracts by high performance liquid chromatography (hplc) analysis. when susceptible plants are exposed to allelochemicals, germination, growth and development may be affected. the most reported gross morphological effects on plants by allelochemicals are retarded seed germination, effects on coleoptile elongation and on radicle, shoot and root development (kruse et al,. 2000). weir et al,. (2004) declared that inhibition of photosynthetic rate, interruption of respiration; atp synthesis and amino acids metabolism were major physiological and biochemical mechanism that might be mediated by allelochemicals. inhibition % of number of leaves is lower than other measured characters for all tested varieties (figure 1b). according to the results observed ld 365 showed the highest inhibition % for all above measured variables and the lowest was the herathbanda (figure 1). as far as ld 365 short duration variety is concerned, it inhibit plant height, number of leaves, germination and dry weight by 72.2%, 44.6%, 74.2% and 82.6% respectively when 6 g of rice residue incorporated to the mixture (fig 1). these results indicate that residues of ld 365 may have higher allelopathic potential against barnyard grass growth and development. dilday et al. (1994), olofsdotter et al. (1995), chung et al. (1997) and ahn and chung (2000) have conducted several experiments using rice residue extracts and rice residue incorporation with silica sand to compare allelopathic characteristics of various rice varieties and results showed that variations in allelopathic activity exist among tested rice varieties. a study conducted by khan and vaishya (1992) also reported the rice residue in soil inhibited the population and biomass of echinochloa colona. furthermore, khanh et al., (2007) also reported residues of rice variety “sarjoo 28 52” blended into the soil (5-6 cm in depth, 5 tons ha -1 ) suppressed jungle rice (echinochloa colona), monarch redstem (ammania baccifera l.), ammania multiflora roxb., and gulf leaf flower (phyllanthus fraternus webster). in addition, several experiments also revealed that decomposing plant residues may either inhibit or stimulate plant growth, and that inhibition may be confined to a limited period, i.e., the most severe inhibition by plant residues occurs at the early stages of residue decomposition, whereas at later stages the inhibition declines while stimulation gradually emerges (an et al., 1998) figure 1: comparison of inhibition percentages of barnyard grass plant height (a), number of leaves (b), seed germination (c) and dry weight (d) by different amount of rice residues of selected rice varieties incorporated with sand. the difference in response was attributed to the genetic differences among the varieties, since the amounts of rice residues incorporated were the same. however, this allelopathic activity may be a result of higher concentrations of same chemical or a combination of different chemicals. because, ranagalage et al. /journal of tropical forestry and environment vol. 4. no 02 (2014) 24-30 29 there are possibilities in decomposing rice residues may produce different amount of one or more allelopathic substances. furthermore, the final outcome of allelopathic potential determined not only allelopathic substances itself, but also various other environmental and management practices are influenced. therefore, further experiments in field conditions are needed to explore weed suppression ability of rice residues of selected rice varieties. 4. conclusion the objective of this study was to examine allelopathic potential of rice residue of different rice varieties. results revealed that incorporating rice residue to paddy soil would be able to inhibit seed germination and growth of barnyard grass in some extend. therefore, incorporation of residue to paddy soil is help to reduce competitiveness of barnyard grass and thereby reduced weed growth. results also revealed that the allelopathic characters differ among tested rice varieties. on the basis of measured variables ld 365 is the most allelopathic cultivar out of rice cultivars tested in this study. traditional cultivar herathbanda showed the lowest performance. furthermore, suppression of seed germination and growth of barnyard grass was increased when increasing amount of rice residue incorporated with sand indicating the importance of studying weed suppressing ability of rice residues as it might reduce application of herbicides by the farmers. isolation and identification of allelochemicals of selected varieties are also important for further analysis of allelopathic characters of rice. references ahn, j.k. and chung, i.m. 2000. allelopathic potential of rice hulls on termination and seedling growth of barnyard grass. agron. j., 92:1162-1167. aldrich, j.d. 1984. weed-crop ecology: principles and practices. breton publishers, pp.215-241. an, m., pratley, e. and haig, t. 1998. allelopathy from concept to reality environmental and analytical laboratories and farmer center for conservation farming, charles sturt university, waggansw 2656 bhadoria, p.b.s. 2011. allelopathy: a natural way towards weed management. american journal of experimental agriculture, 1(1):7-20 chou, c.h. 1995. allelopathy and sustainable agriculture. in: inderjit dakshini kmm and einhelling fa (eds.), allelopathy: organisms, process, and application. acs symposium series 582. american chemical society, washington, dc, pp. 211–223. chou, c.h. 1999. role of allelopathy in plant biodiversity and sustainable agriculture. crit. rev. plant sci., 18:609–636. chung, i.m., ahn, j.k. and yun, s.j. 2001a. assessment of allelopathic potential of barnyard grass (echinochloa crus-galli) on rice (oryza sativa l.) cultivars. crop protection, 20:921-928. chung, i.m., ahn, j.k. and yun, s.j. 2001b. identification of allelopathic compounds from rice (oryza sativa l.) straw and their biological activity. canadian journal of plant sciences, 81:815-819. chung, i.m., kim, k.h., ahn, j.k. and ju, h.j. 1997. allelopathic potential of rice varieties on echinochloa crus-galli. korean journal of weed science, 17:52-58. chung, i.m., kim, k.h., ahn, j.k., chun, s.c., kim, c.s., kim, j.t. and kim, s.h. 2002. screening of allelochemicals on barnyardgrass (echinochloa crus-galli) and identification of potentially allelopathic compounds from rice (oryza sativa) variety hull extracts. crop protection, 21:913920. chung, m. and mille, d.a. 1995. allelopathic influence of nine forage grass extracts on germination and seedling growth of alfalfa. agron. j. crop res., 8:180-185. 30 courtois, b. and olofsdotter, m. 1998. incorporating the allelopathy trait in upland rice breeding programs. in: olofsdotter m (ed.) allelopathy in rice. manila, philippines: int. rice research institute, pp. 57-68. dilday, r.h., lin, j. and yan, w. 1994. identification of allelopathy in the usda-ars rice germplasm collection. aust. j. exp. agric., 34:907-910. dilday, r.h., yan, w.g., moldenhauer, k.a.k. and gravois, k.a. 1998. allelopathic activity in rice for controlling major aquatic weeds. in olofsdotter m. (ed.) allelopathy in rice. manila, philippines: int. rice research institute, pp.7-26. fujii, y. 1992. the potential biological control of paddy weeds with allelopathy-allelopathic effect of some rice cultivars. proceedings of the international symposium on biological control and integrated management of paddy and aquatic weeds, tsukuba, japan, pp.305-320. garrity, d.p., movillon, m. and moddy, k. 1992. differential weed suppression ability in upland rice cultivars. agron. j., 84:586-591. hassan, s.m., aidy, i.r. and bastawish, a.o. 1994. allelopathic potential of rice varieties against major weeds in egypt. in: proceedings weed science society of america meeting, seattle, washington, usa, 63. im, i.b., guh, o.j. and oh, y.j. 1993. weed occurrence and competitive characteristic under different cultivation types of rice (oryza sativa l.). 3. difference in weed occurrence and rice growth under the competitive periods. korean journal of weed science, 13:114–121. khan, a.h. and vaishya, r.d. 1992. allelopathic effects of different crop residues on germination and growth of weeds. proceedings of the first national symposium on allelopathy in agroecosystems. indian society of allelopathy, haryana agricultural university, hisar, india, pp.50-60. khanh, t.d., xuan, t.d. and chung, i.m. 2007. rice alleloapthy and the possibility for weeds management. annals of applied biology, 151: 325-339. kim, k.u. and shin, d.h. 2003. the importance of allelopathy in breeding new cultivars, in weed management for developing countries. fao plant production and protection paper no. 120 (ed 1) ed. labrada r., editor. (rome: food and agriculture org.) pp.195-210. kruse, m., strandberg, m. and strandberg, b. 2000. ecological effects of allelopathic plants: a review. national environmental research institute, silkeborg, denmark. neri technical report, pp.315: 66 labrada, r. 1996. weed management in rice. in auld, b.a. & kim, k.u. eds. fao plant production & protection paper no. 139, fao, rome, pp.259-272 lin, j., smith jr, r.j. and dilday, r.h. 1992. comparison of allelopathic rice and bensulfuron for aquatic weed control in rice. wssa abstr., pp. 33:170. moody, k. 1995. sustainability in rice weed management. in: proceedings of the 15 th asians-pacific weed science conference, tsukuba, japan, pp.93-103. olofsdotter, m., navarez, k. and moody, k. 1995. allelopathic potential in rice (oryza sativa l.). annals of applied biology, 127:543-560. putnam, a.r. 1985. allelopathic research in agriculture: past highlights and potential. in: thompson ac (ed.), the chemistry of allelopathy. acs symposium series. american chemical society, washington, dc, pp.1-8. reigosa, m.j., sanchez-moreiras, a. and gonzalez, l. 1999. ecolophysiological approach in allelopathy. crit. rev. plant sci., 18: 577-608. rice, e.l. 1984. allelopathy, 2nd edition. academic press, orlando, florida. p422. weir, t.l., park, s.w. and vivanco, j.m. 2004. biochemical and physiological mechanisms mediated by allelochemicals. current opinion plant biology journal, 9:195-203. amusa et al. /journal of tropical forestry and environment vol. 4. no 02 (2014) 73-81 73 stock density and fruit yield of african walnut in tropical lowland rainforests of southwest nigeria t.o. amusa 1* , s.o. jimoh 2 , i.o. azeez 2 , r.o. awodoyin 3 and i. kareem 4 1 department of forest resources management, university of ilorin, nigeria 2 department of forest resources management, university of ibadan, nigeria 3 department of crop protection and environmental biology, university of ibadan, nigeria 4 department of agronomy, university of ilorin, nigeria date received: 28-06-2014 date accepted: 03-07-2014 abstract despite the high socio-economic potentials of african walnut, plukenetia conophora mull-arg, there is a dearth of information on stock density and yield studies under different site conditions. therefore, this study was carried out to investigate the stock density and fruit yields of p. conophora in three different habitats (i.e. less disturbed natural forest, recently disturbed natural forest and plantation forest) within omo forest reserve (ofr) and shasha forest reserve (sfr) of nigeria. stratified random sampling was used to carry out the inventory survey. fruit yields were determined by collecting fruit falls through double sampling approach. both descriptive and inferential statistics were used in analysing the data at p=0.05. stock densities of p. conophora were 5.33+1.7 stands/ha, 14.67+2.05 stands/ha and 16.00+2.94 stands/ha in ofr, while they were 7.33+0.47 stands/ha, 14.67+1.25 stands/ha and 10.67+04.7 stands/ha in sfr for recently disturbed forest, less disturbed forest and plantation forest respectively. there were significant differences in number and distribution of species by forest types, but not between forest reserves. the mean yield of p. conophora was estimated at 7,800 kg/ha/yr for ofr and 6,534 kg/ha/yr for sfr. yields from plantation area contributed more in ofr, while yields from less disturbed natural forest area were higher in sfr. yields from recently disturbed natural forest were consistently lower in the two reserves. these results show that p. conophora thrives better in plantation and old re-growth forests. this information is pertinent towards improving the management of the species, increase its productivity and enhance benefits in a more sustainable manner to the rural populace. keywords: african walnut; density; yield; tropical lowland rainforests introduction the african walnut, plukenetia conophora mull-arg (syn. tetracarpidium conophorum) is one of the top priority non-timber yielding plant species within the tropical lowland rainforest of southwestern nigeria (amusa and jimoh, 2012). it is a perennial woody climber belonging to the family euphorbiaceae in the order malpighiales. it is found mostly in the southern and western regions of nigeria as well as other west and central african countries including sierra-leone, benin, cameroun, equitorial guinea and gabon (dalziel, 1937). p. conophora is widely harvested from natural forests, * correspondence: teejayui@gmail.com tel: +234 08051750289 issn 2235-9370 print/issn 2235-9362 online © university of sri jayewardenepura 74 plantations, compound farms and multi strata agroforestry systems. the leaves, bark, root and fruit of the species are considered to have medicinal properties (samson et al., 2014). according to ajaiyeoba and fadare (2006), the leaves of p. conophora are used for the treatment of dysentery and to improve fertility in males. the bark is used in tea as laxative, chewed for toothache, prevent and control high blood pressure and also as a male fertility agent. the root is used for treatment of haemorrhoids, frost bite and varicose ulcers (samson et al., 2014). the main economic importance of the species lies in the edibility of its oil-rich seeds or nuts, which are consumed by many as a snack and delicacy within its distributional range. it is a soup thickener and an antidote against snake bite. also, the oil is fast drying and has been used in the formulation of wood varnish, stand oil, vulcanized oil for rubber and leather substitute (awodoyin et al., 2000; jiofack et al., 2013). the importance of p. conophora as an indigenous fruit climber is high as it is a multi-purpose crop. local populations within the west and central african region exploit the seeds to generate incomes to enhance their social and economic need (jiofack et al., 2013). despite the huge socioeconomic potentials of this species, information on stock density and yield studies under different site conditions are inadequate. yet, one of the prerequisite to enhancing the contribution of non-timber forest products to forest conservation and sustainable management is research that provides baseline information and scientific assessment of their potentials. therefore, this study was carried out to investigate the stock density and fruit yield of p. conophora in different habitats within the tropical lowland rainforest of omo and shasha forest reserves, southwest nigeria. this is important in order to improve the management of the species, increase its productivity and enhance benefits in a more sustainable manner to the rural populace who are usually smallholder farmers. 2. methods and materials 2.1 the study area the study was carried out in omo and shasha forest reserves (figure 1) located within the tropical lowland rainforest zone of southwestern nigeria. omo forest reserve (ofr) is located between latitudes 6 0 35 / -7 0 05 / n and longitudes 4 0 19 / -4 0 40 / e in the ijebu east and north local government areas of ogun state, southwestern nigeria. the reserve covers an area of about 132,500 ha (oates et al., 2008) forming common boundaries with osun, ago-owu and shasha forest reserves in osun state and oluwa forest reserve in ondo state, all of which also share some common natural endowments. the nigerian government legally gazetted it a forest reserve in 1918. the government in 1946 established a 460 ha strict nature reserve (snr) within omo forest reserve. this was upgraded to a biosphere reserve (br) in 1977 by unesco (obioho, 2005). however, going by the unesco website’s description, the entire ofr could aptly be referred to as a biosphere reserve (http://www.unesco.org/mab/brs.shtml). a biosphere reserve combines a core protected areas with zones where sustainable development is fostered by local dwellers and enterprises. still, except in the snr, all the remaining natural forest in the reserve has been heavily damaged by many years of logging, which continues at a high rate. the vegetation of the reserve is a mixed moist semi-deciduous rainforest. earlier works reported by okali and ola-adams (1987) distinguished a dry forest in the northern part and a humid forest in the southern part. the plant families with the most abundant individuals include araceae, asteraceae, ebenaceae, lilliaceae, papilionoideae, poaceae, rubiaceae and violaceae. the most common tree species are diospyros spp., drypetes spp., strombosia pustulata, rinorea dentata and voacanga africana (ojo, 2004). oates et al., (2008) in a survey coordinated by the nigerian conservation foundation (ncf) revealed that omo’s rainforest contains other important species of trees including: oil palms (elaeis guineensis), bamboo (bambusa vulgaris), amusa et al. /journal of tropical forestry and environment vol. 4. no 02 (2014) 73-81 75 rattans (calamus spp), rubber (hevea brasiliensis) and african mahogany (khaya spp) and possibly still contains the iroko (milicia excela). in many parts of the forest there is dense undergrowth and a low density of large trees. the rainy season in ofr usually commences in march. the mean annual rainfall in the area ranges from about 1,600 to 2,000 mm with two annual peaks in june and september, with november and february being the driest months (isichei, 1995). temperature ranges from 21.40 0 c to 32.15 0 c and a minimum relative humidity of 76.34% (adebisi, 2004). a large chunk of the forest (94,380 ha) was converted to gmelina arborea monoculture in the early eighties in a programme assisted by loans from the world bank and the african development bank to provide material for a pulp mill at iwopin (which is now moribund). oates et al. (2008) estimated total area of remaining natural forest in the reserve at 230 km 2 (23,000 ha). for effective management, the reserve was subdivided into areas or sectors called j1, j3, j4 and j6. these sub-divisions were apportioned to people already living in the reserve in isolated villages or camps called enclaves. in addition to these settlements (which have continued to grow), large numbers of migrant farmers have moved into the reserve, some of them encouraged as taungya farmers to help create the gmelina plantations. within the various sectors there are several settlements. estimated total population in the area is put at between 20,000 and 25,000 people. the communities are farming communities that rely on the forest as a supplementary source of livelihood. farming, fishing, hunting and collection of non-timber forest products are the predominant occupations for the majority of the enclaves’ population. on the other hand, shasha forest reserve (sfr) is located between latitudes 7 0 00 / -7 0 30 / n and longitudes 4 0 00 / -5 0 00 / e in ife south local government area of osun state, southwestern nigeria. the reserve was gazetted in 1925 as part of the old shasha forest reserve. it shares boundaries with omo forest reserve on the west. the northern and eastern boundaries are with ife native authority reserve and oluwa forest reserve in osun and ondo states respectively. the total area of the reserve is around 31,000 ha (balogun, 2007; oates et al., 2008). out of this, about 6,920 ha is under plantations of various species such as gmelina arborea, tectona grandis, terminalia spp, pinus spp and nauclea diderichii. the remaining 24,080 ha is currently dominated by pockets of degraded natural forests characterised with broken canopies. the original vegetation structure of the reserve is three storied with scattered emergents (jimoh, 2002). plants with the most abundant families include: sterculiaceae, ebenaceae, olacaceae, euphorbiaceae and flacaurtiaceae. currently, the vegetation of the reserve is dominated by pockets of degraded natural forests with broken canopy structure and plantations of exotic forest species as well as few indigenous species. the climate of sfr as described by kio (1978 cf. jimoh, 2002) comprises two peaks of rainfall in july and september. the rainy season usually commences from march/april and lasts till november. there is also a short dry spell in august. total annual rainfall ranges from 887 mm to 2,180mm. rainfall also occurs at irregular interval during the dry season with about 10% of the total annual rainfall occurring within the period. the mean annual temperature averages 26.5 0 c with annual range of between 19.5 0 c and 32.5 0 c. the reserve is sub-divided into two major areas viz, area 4 and area 5. there are about 40 communities within and around the reserve. they engage in cocoa farming, hunting, forestry works, produce-buying and selling and other menial activities. the population of these communities range from 200 to as many as 2,000 people. the enclaves within the reserve vary in number and size for both areas 4 and 5. the enclaves are inhabited by people of different ethnic origin who also engage in hunting and non-timber forest products gathering on seasonal basis. the population of each enclave range from ten to one hundred. 76 2.2 methods used stratified random sampling was used to carry out inventory survey of p. conophora in the study area. each of the forest reserve was stratified into three viz; less disturbed natural forest (for areas that have been spared of human perturbation for at least ten years); recently disturbed natural forest (for areas that have suffered one form of human perturbation or the other in the last five years); and plantation forest (for areas carrying plantation species). following a tested methodology for non-timber forest products assessment (hall and bawa 1993; sunderland and tchouto 1999; siebert 2004), the inventory consisted of a series of temporary, parallel, 10 m-wide belt transects established along a baseline. in each stratum (as defined above), three belt transects of 500 m×10 m were laid along a predefined compass bearing. enumeration was done carefully along the belt transect within 5 m on either side of the central line for all individuals of the species. a total of nine transects were inventoried in each reserve. figure 1: map of omo-shasha forest reserve complex. in order to determine yield, specific stands of p. conophora were randomly selected, marked and monitored within the different forest stratification enumerated earlier. this represents sub-samples from inventory of population, an approach referred to as double sampling by wong (2000). the yield measurement involved 24 stands, representing 12 stands in each forest reserves and four stands in each forest type. fruit yield was determined by collecting fruit falls in plots at every 7-10 days interval. each amusa et al. /journal of tropical forestry and environment vol. 4. no 02 (2014) 73-81 77 collection was weighed and recorded. values obtained were applied to the inventory of stock densities to give gross product yield of the study area. this was done by deriving a conversion factor. in this case, the mean weights of product per individual plant (kg) multiplied by the estimated total number of individuals in the population was used (peters 1996; wong 2000). the data obtained through inventory survey on p. conophora was used in determining the stock density and distribution of the species. the hypothesis that: there is no significant difference in the number and distribution of the species by forest type in the study area was tested using the kruskalwallis test at p<0.05. the friedman test was further used to analyse for differences in the number and distribution of the species for the two forest reserves. the test was also carried out at p <0.05. 3. results p. conophora was fairly prevalent in all forest types sampled for both omo and shasha forest reserves. more stands of the species were found in the plantation area in ofr. in the reserve, stock densities of p. conophora range from 5.33+1.7 stands/ha in recently disturbed natural forest to 14.67+2.05 stands/ha in less disturbed natural forest and 16.00+2.94 stands/ha in plantation area. in sfr, stock densities were 7.33+0.47 stands/ha in recently disturbed natural forest, 10.67+04.7 stands/ha in plantation area and 14.67+1.25 stands/ha in less disturbed natural forest (table 1). there were no differences in mean densities of p. conophora for all sites in the two reserves. kruskal-wallis test, however, showed significant differences in densities and distribution of the species by forest type in both reserves (ofr; kruskal-wallis chi-squared=16.2399, df=2, p-value=0.0002975; sfr; kruskalwallis chi-squared=18.4265, df=2, p-value=9.971e-05). the friedman test showed no significant difference in the density and distribution of the species for the two forest reserves (friedman chisquared=0, df=1, p-value=1; figures 2 and 3). generally, p. conophora seems to be well adapted in all the forest types and grows in association with taller trees. table 1: current population status of plukenetia conophora in omo and shasha forest reserves. the mean yield of product (nuts) produced per hectare per year was estimated at 7,800.00 kg for ofr and 6,534.00 kg for sfr (table 2). the total yield of product produced per hectare per year was estimated at 23,400.00 kg for ofr and 19,602.00 kg for sfr. mean yield of product available was estimated at 780,000.00 kg (780.00 tonnes) and 110,745.76 kg (110.75 tonnes) for ofr and sfr respectively. yields from plantation area contributed more in ofr, while yields from stands in natural site (forest types) forest reserve ofr sfr total number of individuals in each forest types mean number of individuals per hectare total number of individuals in each forest types mean number of individuals per hectare plantation area 24 16.00 16 10.67 natural forest (rested for the past 10 years and above) 22 14.67 22 14.67 natural forest (disturbed within the past 5years) 8 5.33 11 7.33 mean (all sites) 18 12 16.33 10.89 78 s t a n d p o p u l a t i o n forest area (rested for the past 10 years and above) contributed more to overall estimate in sfr. yields from disturbed natural forest were consistently lower in the two forest reserves. extrapolating for the total stock of product (fruit) currently available in the two forest reserves with sampling intensities of 0.010% and 0.034% for ofr and sfr respectively gives estimates of 2,340,000.00 kg (2,340 tonnes) in ofr and 332,237.28 kg (332.28 tonnes) in sfr. figure 2: box plot of number of plukenetia conophora in ofr by forest types. figure 3: box plot of number of plukenetia conophora in sfr by forest types. amusa et al. /journal of tropical forestry and environment vol. 4. no 02 (2014) 73-81 79 table 2: yield estimates (kg) of plukenetia conophora nuts in omo and shasha forest reserves. 4. discussion the reported stock densities within the different habitat types in this study compared favourably well with the mean value (14 stems/ha) obtained by jiofack et al., (2013) in their inventory of p. conophora within some cocoa-based agroforestry systems in cameroun central region. stock densities of p. conophora in our study were higher than what was obtained by udoh et al. (2009) for climber species in their study of life-form and density of valuable non-timber plants in ukpom community forest, akwa ibom state, nigeria. udoh et al. (2009) had reported climber species population densities of 51.0/ha, 47.0/ha, 10.0/ha, 2.0/ha and 1.0/ha for ancistrophyllum secundiflorum, calamus deerratus, gnetum africanum, piper guineense and p. conophora respectively. the authors’ reported value for p. conophora was attributed to unfavourable micro-climate and paucity of viable seeds to sustain regeneration in the study area. furthermore, the shading effect of sunlight and the allelopathic nature of some tree plant species were thought of as probable explanation for difficulty of climbers to thrive in the area. essentially, stock density and population distribution of plant species are influenced by biotic and abiotic conditions of their habitats. however, it is noteworthy that woody climbers have been reported to be increasing in dominance, relative to trees, in both tropical and temperate forests (wright et al., 2004; allen et al., 2007; swaine and grace, 2007). this pattern has been related to climate change, although more empirical evidence is needed. nevertheless, it has been suggested that the dominant climbers in the southern temperate rainforest could be able to cope with land-use change, if forest clearings occur due to human activities. this was attributed to the expression of ecophysiological traits in climbers in relation to light exploitation (gianoli et al., 2012). gianoli et al. (2012) established significant association between the dominance of climbing plant species across light environments and changes in ecophysiological traits between forest understory and canopy gaps. this may also underscore the importance of fruit-bearing woody climbers such as p. conophora in the livelihoods of forest communities in the light of global change drivers, including land-use change and climate change in the tropics. site (forest types) forest reserve ofr sfr stock of products per hectare (kg) in each forest types stock of products for entire forest reserve (kg) stock of products per hectare (kg) in each forest types stock of products for entire forest reserve (kg) plantation area 10,400.00 1,040,000 6,402.00 108,508.47 natural forest (rested for 10 years and above) 9,535.50 953,550.00 8,802.00 149,186.44 natural forest (disturbed within the past 5 years) 3,464.50 346,450.00 4,398.00 74,542.37 total available stock (all sites) 23,400.00 2,340,000.00 19,602.00 332,237.28 mean (all sites) 7,800.00 780,000.00 6,534.00 110,745.76 80 results obtained on fruit yield in this study contrast sharply with the findings of awodoyin et al. (2000) who reported a seed yield of 336.17 kg/plant at six years after planting in a simulated environment within southwest nigeria. higher fruit and seed yield reported in our study may be a pointer to the fact that p. conophora naturally thrives better in plantation and old re-growth forests. in view of the recent trend in participatory forestry programmes, the socioeconomic contributions of p. conophora provide an opportunity to integrate the crop under multiple land-use system within the forest landscape. estimates of yield of non-timber forest products such as p. conophora would also be of immense practical utility to forest managers and locals. this would allow for the setting of sustainable harvest limit for each product over a given period of time. 5. conclusion it is an established fact that deforestation, climate and habitat changes are major drivers of gene pool erosion in many plant species in the tropics. to enhance the conservation of germplasm of species and their contributions to sustainable livelihood in the region, there is need for baseline information and scientific assessment of their potentials. this study has reported considerable population densities for p. conophora under the different habitat types investigated. there was an established trend that p. conophora thrives better in plantation and old re-growth forests. this information is pertinent towards improving the management of the species, increase its productivity and enhance benefits in a more sustainable manner to the rural populace. acknowledgements we express our sincere gratitude to village leaders and communities in the project area for providing the enabling environment to carry out the work. we deeply appreciate the assistance in logistics and personnel provided by the management authorities of omo and shasha forest reserves, southwest nigeria. references adebisi, a.a., 2004. a case study of garcinia kola nut production-to-consumption system in j4 area of omo forest reserve, south-west nigeria. forest products, livelihoods and conservation: case studies of non-timber forest product systems africa, sunderland, t. and ndoye, o. eds. centre for international forestry research (cifor), bogor, indonesia, 2: 115-132. ajaiyeoba, e. o. and fadare, d. a. 2006. antimicrobial potential of extracts and fractions of the africanwalnut. african journal of biotechnology, 5(22): 2322-2325. awodoyin, r. o., egunjobi, j. k. and ladipo, d. o. 2000. biology, germination and prospects for the domestication of the conophor nut, plukenetia conophora mull. arg. [syn. tetracarpidium conophorum (mull. arg.) hutch. & dalz.]. journal of tropical forest resources, 16(1): 30-38. bada, s.o, 1999. community participation in the management of omo forest reserve. final report for formecu, federal department of forestry, abuja, nigeria, pp.44. balogun, b.o, salami, a.t. and oloyede-kosoko, s.o.a. 2007. geospatial data application in the assessment of population impact on a tropical lowland rainforest of southwest nigeria. paper presented at the unoosa/morocco/esa international workshop on the use of space technology for sustainable development, rabat morocco, 25–27 april, 2007, pp.19 dalziel, j. m., 1937. the useful plants of west tropical africa. whitefriars press, london. gianoli, e., saldana, a. and jime´nez-castillo, m. 2012. ecophysiological traits may explain the abundance of climbing plant species across the light gradient in a temperate rainforest. plos one 7.6:e38831. doi:10.1371/journal.pone.0038831. amusa et al. /journal of tropical forestry and environment vol. 4. no 02 (2014) 73-81 81 hall, p., bawa. 1993. methods to assess the impact of extraction of non-timber tropical forest product on plant population. economic botany, 47: 234247. isichei, a.o. 1995. omo biosphere reserve, current status, utilization of biological resources and sustainable management (nigeria). working papers of the south-south cooperation programme on environmentally sound socio-economic development in the humid tropics. unesco, paris, pp.52. jimoh, s.o. 2002. a multiple use planning model for tropical rain forests: the case of sasha forest reserve, nigeria. ph.d. thesis submitted to the department of forest resources management, university of ibadan, nigeria, pp.248. jiofack t., tchoundjeu, z., guedje n.m., lejoly j., fokunang c. and mate, m. 2013. can the contribution of the african walnut diversifying cocoa agro forests being profitable for local stallholders in cameroon? wudpecker journal of agricultural research, 2.5: 142 – 150. oates, j.f., ikemeh, a.r., ogunsesan, a.a. and bergl, r.a. 2008. a survey of the rainforests in ogun, ondo and osun states in south-western nigeria to assess options for sustainable conservation. report prepared for the nigerian conservation foundation. pp.48. obioho, g.i.b. 2005. ecological ethnobotany and the management of omo biosphere reserve, nigeria. proceedings of the 30 th annual conference of the forestry association of nigeria on sustainable forest management in nigeria: lessons and prospects. 7-11 th november, 2005. popoola, l. mfon, p. and oni, p.i. eds. kaduna, pp.86-91. ojo, l.o. 2004. the fate of a tropical rainforest in nigeria: abeku sector of omo forest reserve. global nest, 6(2): 116-130. okali, d.u.u. and ola-adams, b.a. 1987. tree population changes in treated rainforest at omo forest reserve, nigeria. journal of tropical ecology, 3: 291-313. peters, c.m. 1996. the ecology and management of non-timber forest resources. world bank technical pp.322. world bank, washington, pp.157. samson s. e., mitsan o., samuel e. u., yomi r. a., alfred f. e. and comfort b. e. 2014. antibacterial activity of methanolic leaf extract of plukenetia conophora mull. arg. against selected bacteria isolated from urinary tract infection. international journal of microbiology and application, 1(1): 1-10. siebert, s.e. 2004. demographic effects of collecting rattan cane and their implications for sustainable harvesting. conservation biology, 18: 424-431. sunderland, t. c. h. and tchouto, p. 1999. a participatory survey and inventory of timber and nontimber forest products of the mokoko river forest reserve, sw province, cameroon. report for usaid/carpe, pp.43. swaine, m.d. and grace, j. 2007. lianas may be favoured by low rainfall: evidence from ghana. plant ecology, 192: 271–276. udo, e.s., olajide, o. and udoh, e.a., 2009. life-form and density of valuable non-timber plants in ukpom community forest, akwa ibom state, nigeria. african research review, 3(3): 73-80. wong, j.l.g. 2000. the biometrics of non-timber forest product resource assessment: a review of current methodology. research paper for the european tropical forest research network (etfrn), department for international development (dfid), uk, pp.109. wright, s.j., caldero´n, o., herna´ndez, a. and paton, s. 2004. are lianas increasing in importance in tropical forests? a 17-year record from barro colorado island, panama´. ecology, 85: 484–489. siriwardena and arambewela /journal of tropical forestry and environment vol. 4. no 02 (2014) 57-63 57 determination of volatile constituents of the essential oil and absolute of nyctanthes arbortristis l. flowers grown in the wet zone of sri lanka v.s. siriwardena * and l.s.r. arambewela college of chemical sciences, institute of chemistry, rajagiriya, sri lanka date received: 17-01-2014 date accepted: 01-08-2014 abstract the volatile constituents of the essential oil and absolute of nyctanthes arbortristis l. flowers grown in the wet zone of sri lanka were investigated in this study. hydro-distillation and solvent extraction methods were used to obtain the essential oil and the absolute respectively. the volatile samples were analysed by gc-ms techniques. this study led to the identification of 48 chemical constituents of the essential oil and 4 in the absolute. the essential oil composition was dominated by phytol (32.2%) and methyl palmitate (14.7%). other well-known volatile constituents such as linalool (0.8%), eucarvone (0.9%), phytone (1.4%), nonadecane (2.3%), methyl myristate (1.1%), cis-9tricosene (3.6%), n-pentacosane (1.6%) and geranylgeraniol (2.7%) were also identified in the essential oil. the absolute was dominated by butyl acetate (80.8%) followed by phenethyl acetate (1.7%), linalool oxide (1.4%) and 2-butoxyethyl acetate (1.4%). keywords: nyctanthes arbortristis, essential oil composition, methyl palmitate, phytol; absolute 1. introduction nyctanthes arbortristis l. is a large shrub with fragrant flowers that open at dusk and finish at dawn, and belongs to the family oleaceae, to which jasminum species also belongs. the plant is also known as coral jasmine or sepalika in sinhala (moldenke and moldenke, 1983). its flowers are perceived to have fragrance “similar to jasmine” (the wealth of india, 1997) and could be described on simple terms so as to possess saffron spicy, honey suckle, sweet floral hints of jasmine (http://www.evanhealy.com/home/article/35). nyctanthes arbortristis is grown in asian countries like sri lanka, india, thailand, indonesia, etc. (moldenke and moldenke, 1983). its flowers usually bloom from july to october and constitute of white petals fixed to a bright orange tubular stalk (sandhar et al., 2011). folk people of tripura of india predict the weather and rainfall variation based on the analysis of total number of flowers and this was scientifically validated by (acharya, 2011). nyctanthes arbortristis flowers are bitter, astringent, carminative, stomachic and used in ophthalmic purposes. they are also used as a tonic to the hair in preventing graying of hair and baldness (sasmal et al., 2007). flowers are also used traditionally to provoke menstruation (champa et al., 2012). * correspondence: viransanjaya@yahoo.com tel: +61 423250689 issn 2235-9370 print/issn 2235-9362 online © university of sri jayewardenepura 58 in vitro antiplasmodial activity (champa et al., 2012) and antifilarial activity (sandhar et al., 2011) were shown by ethanolic and chloroform extracts of the flowers respectively. both these activities could be attributed to the occurrence of rengyolone which is a non-cytotoxic compound (sasmal et al., 2007). the hot flower infusion of n. arbortristis was reported to have sedative and diuretic effects on rats (ratnasooriya and jayakody, 2004; sasmal et al., 2007). the isolated carotenoid aglycone ag-ny1 from the orange colored tubular calyx of flowers, exhibited good membrane stabilising activity as described (sandhar et al., 2011). three other carotenoid glycosides were also isolated from the corolla tubes of the plant (vankar, 2008). the ethanolic extract of the orange tubular calyx of n. arbortristis and the isolated carotenoid showed significant inhibition of rat paw edema (champa et al., 2012). it was demonstrated that n. arbortristis flowers exhibit various beneficial bioactivities, including antispasmodic, antidiabetic, antihelmintic and immunostimulant, antiinflammatory and hepatoprotective activities (sandhar et al., 2011). studies suggest that flowers have somewhat less antioxidant capacity than the leaves. it has been proven that the water extract of flowers has radical scavenging activity with their calyx having the most (vankar, 2008). both enzymatic and non-enzymatic antioxidants in the flowers have been investigated by (ramapriya and usha, 2010). they have found that there is significant difference in the two levels of antioxidant assays. work carried out by (nagavani et al., 2010) also supports the above conclusion. the flowers were reported to contain coloring matter nyctanthin (identical with α-crocetin from saffron) as well as d-mannitol, tannin, iridoid glycosides (sandhar et al., 2011). the oil obtained by the water distillation method (yield, 0.0045 %) was soluble in absolute alcohol with slight turbidity as described (the wealth of india, 1997). the concrete was obtained by extraction with benzene and a 0.058 % yield (the wealth of india, 1997). the essential oil contains α-pinene, p-cymene, 1-hexanol, methylheptanone, phenylacetaldehyde, 1-decanol and anisaldehyde as described (champa et al., 2012). another study carried out on flowers of bangladesh (rahman et al., 2011) reported phytol and 2methyloctadecane as major constituents from the essential oil of petal and corolla tube, respectively. although sri lankan ayurveda system uses the plant for its medicinal applications, the sepalika plants grown in sri lanka were less studied, except for a few work cited in literature (ratnasooriya and jayakody, 2004; ratnasooriya et al., 2005). as the volatile constituents of n. arbortristis flowers grown in sri lanka have not been studied the aim of present study is to characterize the volatile constituents of the essential oil and absolute of local n. arbortristis flowers. 2. methodology 2.1 plant material nyctanthes arbortristis flowers were picked from the ground early morning before sunrise from pannipitiya in sri lanka, and taken to the laboratory for distillation and extraction. the plant was identified at the herbarium of royal botanical gardens, peradeniya, sri lanka. 2.2 hydro-distillation of flowers fresh flowers were hydro-distilled for five hours using a clevenger type apparatus. a mixture of 1:1 hexane and pentane was used to trap the essential oil. after distillation, the trapped essential oil was dried using anhydrous na2so4 and the essential oil was recovered. siriwardena and arambewela /journal of tropical forestry and environment vol. 4. no 02 (2014) 57-63 59 2.3 preparation of the absolute fresh flowers were cut into small pieces and soaked overnight in hexane. the hexane layer was collected and evaporated under reduced pressure. this afforded a semi-solid, dark orange concrete of n. arbortristis flowers. next the concrete was extracted with ethanol. the waxes were filtered off and the ethanol extract was concentrated. 2.4 analysis of the essential oil using gas chromatography-mass spectrometry (gc-ms) gc-ms analysis was performed on agilent 5973 instrument using restek carbowax column (30m 0.25mm i.d., 0.25 μm film thickness) coated with polyethyleneglycol and coupled with a 5973 network mass selective detector (agilent). chromatographic conditions: helium was used as carrier gas at 1.0 ml/min. splitless injection of 1.0 μl of oil. injector temperature was 230 0 c; oven temperature program: initial temperature 40 0 c (held for 5 minutes), raised to 220 0 c at 6 0 c/min and held for 17 minutes. ms interface temperature: 230 0 c, ms mode: ei, ionization voltage: 70.1 ev. compounds were identified using wiley nist database library. the percentages of constituents were calculated leaving out the solvent peak as well as background peaks. 2.5 analysis of the absolute using gas chromatography-mass spectrometry (gc-ms) gc-ms analysis was performed on agilent 5973 instrument using a column (30 m 0.25 mm i.d., 0.25 μm film thickness) coated with (5%-phenyl)-methylpolysiloxane and coupled with a 5973 network mass selective detector (agilent). same chromatographic conditions as above were used except that the injection was in split mode (1:100). oven temperature program: initial temperature 50 0 c(held for 1 minute), raised to 244 0 c (held for 1 minute), final temperature 300 0 c (held for 5 minutes). ms parameters were the same as above. the identification and calculation of composition was carried out as above. 3. results and discussion the hydro-distillation of the flowers of n. arbortrisitis yielded 0.06 % (w/w, wet basis) or 0.76 % (w/w, dry basis) of fragrant essential oil. the essential oil obtained had a light yellow color with a strong floral odor. it congealed at temperatures around 25 0 c. the maceration of flowers in hexane yielded 0.06%, concrete (w/w, based on fresh plant material). the yield is quite similar to the earlier reported value of 0.058% by gupta et al. in 1954 (the wealth of india, 1997). the chromatograms of the essential oil and the absolute obtained in the gc-ms analysis are presented in figure 1 and figure 2. the results of gc-ms analysis are summarized in table 1 and table 2. around forty eight compounds were identified in the essential oil and four in the absolute. 60 figure 1: gc/ms chromatogram of the essential oil of n. arbortristis flowers from sri lanka. figure 2: gc/ms chromatogram of the absolute of n. arbortristis flowers from sri lanka. siriwardena and arambewela /journal of tropical forestry and environment vol. 4. no 02 (2014) 57-63 61 table 1: chemical constituents of the essential oil of n. arbortristis flowers grown in sri lanka. retention time compounds identified % composition in essential oil 4.49 n-decane 0.1 7.36 n-undecane 0.1 10.24 n-dodecane 0.4 11.35 styrene 0.3 12.88 n-tridecane 0.3 15.11 β-isophorone 0.5 15.33 n-tetradecane 0.2 15.99 linalool oxide 0.1 16.32 n-hexadecane 0.4 16.55 α-ionone 0.2 17.57 benzaldehyde 0.3 18.31 linalool 0.8 18.96 α-isophorone 0.2 19.65 methyl benzoate 0.4 20.12 safranal 0.1 20.49 1-hexadecene 0.3 21.00 4-oxoisophorone 0.8 21.18 terpineol 0.2 21.65 eucarvone 0.9 21.84 azulene 0.9 22.48 epoxylinalol 0.1 22.85 methyl salicylate 0.1 23.18 cis-geraniol 0.1 23.46 n-octadecane 0.2 24.01 trans-geraniol 0.1 24.29 1-octadecene 0.2 25.59 neophytadiene 0.2 26.89 methyl myristate 0.5 27.81 hexyl benzoate 0.5 28.56 n-heneicosane 0.9 28.79 phytone 1.4 29.44 methyl iso-palmitate 0.1 29.63 n-eicosane 0.1 30.27 methyl palmitate 14.7 30.60 methyl palmitoleate 0.2 30.79 ethyl palmitate 0.2 31.71 n-nonadecane 2.2 33.24 methyl stearate 1.1 33.62 methyl 11-octadecenoate 0.4 33.85 n-docosane 0.3 34.08 cis-9-tricosene 3.6 34.49 n-pentacosane 1.6 34.72 geranylgeraniol 2.7 35.98 phytol 32.2 36.67 n-tricosane 0.3 37.51 n-heptacosane 0.8 38.53 benzyl salicylate 1.1 40.66 geranyl linalool isomer 0.9 62 table 2: chemical constituents of the absolute of n. arbortristis flowers grown in sri lanka. the major volatile constituents in the essential oil were phytol (3,7,11,15-tetramethyl-2-hexadecene-1ol) and methyl palmitate. phytone, nonadecane, methyl stearate, cis-9-tricosene, n-pentacosane, geranylgeraniol and benzyl salicylate were also present in the essential oil. among the minor constituents, well-known fragrant compounds like linalool oxide, terpineol, eucarvone, geraniol, etc. were present. a range of alkanes starting from n-decane to n-heptacosane were also present in the essential oil. fatty acid esters such as palmitates, methyl myristate and stearate were characterized from the essential oil. two salicylates (methyl and benzyl) and two benzoates (methyl and hexyl) were also present in the flower oil. compounds like isophorones, ionones and safranal could be formed by thermal degradation of carotenoids present in n. arbortristis flowers due to heat applied during hydrodistillation. butyl acetate was the major compound in the absolute. also it is noteworthy that out of four compounds identified in the absolute three were acetates. the study carried out on flowers of bangladesh reported phytol and 2-methyloctadecane as major constituents from the essential oil of petal and corolla tube, respectively (rahman et al., 2011). therefore there are some similarities between the essential oils of flowers of the two countries. nyctanthes arbortristis floral fragrance could be perceived “similar to jasmine” (the wealth of india, 1997) due to the presence of following volatile constituents in both jasminum species and n. arbortristis flowers: linalool, methyl palmitate, phytol, benzaldehyde, methyl salicylate, methyl benzoate, linalool oxide, terpineol, geraniol, geranyl linalool, methyl octadecanoate (http://www.pherobase.com). thus, n. arbortristis could be used instead of jasmine for fragrant purposes. therefore, it could be concluded that n. arbortristis flowers of sri lanka are a good source of fragrance for cosmetic industry. acknowledgements the authors gratefully acknowledge the facilities and financial assistance provided by the college of chemical sciences to carry out this work. references acharya, s. 2011. prediction of rainfall variation through flowering phenology of night-jasmine in tripura. indian journal of traditional knowledge, 10: 96-101. champa, r., chawla, s., mangal, m., mangal, a.k., kajla, s. and dhawan, a.k. 2012. nyctanthes arbortristis linn. (night jasmine): a sacred ornamental plant with immense medicinal potentials. indian journal of traditional knowledge, 11:427-435. el-sayed, a.m. 2014. the pherobase: database of pheromones and semiochemicals. http://www.pherobase.com. accessed 01 february 2014. healy, e. 2014. parijata blossom attar. evanhealy the skin breathes. http://www.evanhealy.com/ home/article/35. accessed 01 february 2014. retention time compounds identified % composition in the absolute 4.05 butyl acetate 80.8 10.92 2-butoxyethyl acetate 1.4 13.34 linalool oxide 1.4 15.62 phenethyl acetate 1.7 siriwardena and arambewela /journal of tropical forestry and environment vol. 4. no 02 (2014) 57-63 63 moldenke, h.n. and moldenke, a.l. 1983. nyctanthaceae, in: moldenke, h. n., moldenke, a.l., dassanayake, m.d., fosberg, f.r. (eds.), a revised handbook to the flora of ceylon. amerind publishing co. pvt. ltd., new delhi, 4, pp.178-181. nagavani, v., raghava, r.k.v., ravi, k.c. and raghava, r.t. 2010. in vitro screening of nyctanthes arbortristis flowers for antioxidant activity and identification of polyphenols by rp-hplc. pharmacologyonline, 2: 57-78. rahman, m.m., roy, s.k., hussain, m. and shahjahan, m. 2011. chemical constituents of essential oil of petals and corolla tubes of nyctanthes arbortristis linn. flower. journal of essential oil bearing plants, 14(6): 717-721. ramapriya, r. and usha, k. 2010. antioxidant potential of the leaves and flowers of nyctanthes arbortristis linn. advanced biotech, 9(7): 40-42. ratnasooriya, w.d. and jayakody, j.r.a.c. 2004. diuretic activity of hot flower infusion of nyctanthes arbortristis in rats. boletin latinoamericano y del caribe de plantas medicinales y aromaticas, 3(5): 84-87. ratnasooriya, w.d., jayakody, w.d., hettiarachchi, a. d. i. and dharmasiri, m.g. 2005. sedative effects of hot flower infusions of nyctanthes arbortristis on rats. pharma. biol., 43(2): 140-146. sandhar, h.k., kaur, m., kumar, b. and prasher, s. 2011. an update on nyctanthes arbortristis linn. internationale pharmaceutica sciencia, 1(1): 77-86. sasmal, d., das, s. and basu, s.p. 2007. phytoconstituents and therapeutic potential of nyctanthes arbortristis linn. pharmacognosy reviews, 1(2): 344-349. the wealth of india: a dictionary of indian raw materials and industrial products, 1997. national institute of science communication, csir, new delhi, pp. 69-70. vankar, v.s. 2008. antioxidant activity of the flower of nyctanthes arbortristis l. international journal of food engineering, 4(8): 11. 54 degree and determinants of host communities’ socio-economic dependence on forest products of pendjari national park, benin republic: automatic linear modelling technique o.e. olaniyi1,4*, b.g. ogunjemite1, o.s. akindele2, e.a. sogbohossou3, m.h. zakaria4 1department of ecotourism and wildlife management, federal university of technology, akure, nigeria 2department of forestry and wood technology, federal university of technology, akure, nigeria 3laboratory of applied ecology, university of abomey-calavi, abomey-calavi, benin 4department of forest management, universiti putra malaysia, selangor, malaysia date received: 17-03-2018 date accepted: 01-11-2018 abstract the study aimed at determining the degree and determinants of host communities’ socio-economic dependence on forest products of pendjari national park, benin. four hundred households in fourteen host communities of the park were subjected to direct household survey through multistage sampling technique. forest dependency indices were computed to determine the households’ dependence on forest products. an automatic linear modelling algorithm through forward stepwise model selection method was employed to model the main determinants to host communities' socio-economic dependence on forest products. household age category (5-14 and above 60 years), total monthly income, education level of the household members (junior/senior high school, bachelor’s degree), place of birth, and religion were the main determinants. most host communities were observed to be dependent on the park in varied forms and degrees, while tanguieta and sangou had the least and highest degree of dependence, respectively. thus, the findings had provided a template for relevant authorities to rightly allocate resources for alternative livelihood means to the ranked host communities. however, a monitoring indicator had been developed to quantify and safeguard the harms of indigenous people to the biodiversity base. this is believed to create a synergy between sustainable development and indigenous peoples. keywords: livelihood, automatic linear modelling, forest products, sustainable development, benin republic 1. introduction socio-economic characteristics of host communities to protected areas are usually believed to have a significant influence on determining the types of activities and interactions toward their natural resources (mehta and heinen, 2001; shibia, 2010; al-subaiee, 2015). they are directly or indirectly related to rural livelihood, and highly determine their forest consumption and degree of forest dependence. over the past years, the recognition of the prevalent dependence of host communities on forest products and the poverty-forest use relationships have generated an increasing scientific concern in demonstrating their socio-economic dependence on forest products and understanding its drivers (mamo et al., 2007; thondhlana et al., 2012; dof et al., 2014; lawry et al., 2015). the dependence of rural households on biodiversity base and their diverse use pattern have become an important topical issue in developing economies (sapkota and oden, 2008) such as benin republic. this interest was due to the need to resolve the devastating trend of forest depletion and poverty amidst inhabitants of host communities to protected areas. *correspondence: oeolaniyi@futa.edu.ng tel: +234 8038555487 issn 2235-9370 print/issn 2235-9362 online ©2017 university of sri jayewardenepura mailto:oeolaniyi@futa.edu.ng olaniyi et al. /journal of tropical forestry and environment vol. 8, no. 02 (2018) 54-68 55 according to meijaard et al. (2013), knowing more about local people usage of forests (such as fuel, medicine, food and food additives, building construction, etc) is an extremely important factor that could enhance planning of land use and minimise the conflict with them. however, the planning and management framework of pendjari national park, benin republic had evolved over the years. specifically, the park was governed by the 1987 law 87-014 and coercion approach was employed until 1993 (cenagref, 1997; tiomoko, 2007). conservation strategies and management of the park resources did not include host communities in coercion approach, which resulted in situations of conflict between communities’ inhabitants and park authority (tiomoko, 2007; belem et al., 2007). currently, the planning and management framework is governed by the law no. 93-009 of 2 july 1993, park zoning (core area, controlled access, habitation and hunting zones) according to unesco (2013) and community conservation approach adapted to accommodating local peoples' needs, empowering their aspirations, promoting their active participation in local resource management, and improving their economic welfare (songorwa, 1999; mehta and heinen, 2001; cenagref, 2005). despite the community conservation approach, the socio-economic characteristics of host communities usually have a significant influence on determining the types of activities and interactions toward their natural resources (mamo et al., 2007; vedeld et al., 2007; babulo et al., 2008; koenig et al., 2011; al-subaiee, 2016). improper knowledge of the interrelationship between the households’ socioeconomic characteristics and their dependence on forest products could hinder the management effectiveness of the park authority in rightly allocating resources for alternative means of livelihood to most dependent communities. this had hindered the rational use of these protected areas’ resources due to the host communities’ over-dependence (igu, 2017; ofoegbu et al., 2017; shrestha et al., 2017; suleiman et al., 2017) and poor protected area planning (fao, 2016). forest dependency indices can be computed to determine the households’ dependence on forest products and it is referred to the average index value of food and food additives, fuel, housing, medicinal and income dependencies (anitha and muraleedharan, 2006). moreover, several methods could be employed to determine the socio-economic determinants of forest dependence. amidst these methods, several studies had recognised the significance of a logistic model over an ordinary least square (ols) linear regression model to deal with socio-economic determinants of forest dependence (lepetu et al., 2009; tieguhong and nkamgnia, 2012). ratner (2012) opined that the challenge of making a decision on which subset(s) of the large pool of potential predictors to include in a linear regression model is very common and arguably the hardest part of regression modelling (miller, 2002; kutner et al., 2004; weisberg, 2005; yan and su, 2009). therefore, the automatic linear modelling algorithm through forward stepwise model selection method (yang, 2013) was employed in this study. in contrast to previous studies, the novelty of the modelling technique is the potential to rank the host communities according to their degree of dependence. this will provide a template for relevant authorities to rightly allocate resources for alternative livelihood means to the ranked host communities. however, it will develop a monitoring indicator to quantify and safeguard the harms of indigenous people to the biodiversity base. thus, the research aimed to rank the host communities based on their dependence on forest products, and determine the determinants of host communities’ socio-economic dependence on forest products of pendjari national park, benin republic. 56 2. methodology 2.1 the study area pendjari national park is located between latitude 10°30’n and 11°31’ n, and longitude 00°50’e and 2°00’ e (figure 1) and covers a land mass of 2,755 km². it is situated in the north-west of benin republic and declared a game reserve in 1954, then upgraded to a national park in 1961. it is bordered to the north by burkina faso (cheke, 2001; nago et al., 2006; assédé et al., 2012). the mean temperature of pendjari national park ranges from 18.6oc to 36.8oc and is characterised by rainfall which varies from 800 mm in the north to 1,000 mm in the south. the park's dry season occurs from november to april and the wet season lasts from may to october (sogbohossou et al., 2014). figure 1: location of pendjari national park in benin republic. 2.1 data collection preliminary surveys were conducted at the study area to ascertain the type of sampling techniques to be used and host communities/households to be sampled according to anitha and muraleedharan (2006). the sampling populations were households’ heads from the host communities of park. a purposive sampling technique based on the host communities’ proximity to the park’s boundary and direct influence on the park was used to select 14 communities from 28 communities that were close to the park. sample size for the study was 400 households daga (40), porga (40), dassari (40), tounsega (32), pouri (32), tiele (16), wantehoun (16), kani (16), nagassega (24), tanguieta (40), tanougou (40), sangou (32), kolegou (16), and batia (16). the computation was based on the population size of 38,250 households and average household size of 7.4 in the host communities of the study area (insae, 2002; insae, 2013; kassa, 2008; cenagref, 2016). the method employed by yamane (1967) was adopted to determine the sample size of the sampled households in each study sites at 95% confidence limit i.e. (1) where; olaniyi et al. /journal of tropical forestry and environment vol. 8, no. 02 (2018) 54-68 57 n = sample size n = population size (number of households) e = error estimate (0.05) a semi-structured questionnaire was designed to retrieve information from the target population. the instrument consisted of two sections (section a–socio-economic characteristics of household; section b–dependency of host communities on the park) with a total of thirty-four items. prior to the study, the questionnaires were validated and cronbach alpha was used to determine the reliability coefficient of the instrument, which was found to be 0.87. 2.3 data analysis for analysis of the questionnaires, descriptive statistics were used and responses of the respondents were converted using likert’s scale. statistical package for social science (spss version 21) software and microsoft excel 2010 spreadsheet were employed to compute the following indices and socio-economic determinants: forest dependency index (fdi) this index was adopted to determine the socio-economic dependence of host communities on the study area. the following forest dependency indices as compounded by anitha and muraleedharan (2006) were computed namely; (1) where; x = 1, if the park is a food and food additives source x = 0, if park is not a food and food additives source xi = number of other food and food additives sources apart from the park (2) where; f = 1, if park is a fuel source f = 0, if park is not a fuel source fj = number of other fuel sources except for fuel from the park (3) where; hi = number of parts of the ith house constructed by using the park’s products h = total number of parts that can be constructed by using park’s products (4) where; m = 1, if the household is using medicine from the park, m = 0 otherwise mi = number of other alternative medicinal options used by the household (5) 58 where; yi = income from the park acquired by the ith family yi = total income of ith family thus, the forest dependence index (fdi) of individual household (6) determinants of host communities’ socio-economic dependence on forest products the automatic linear modelling algorithm (equation 7) through forward stepwise model selection method (yang, 2013) was employed to know the households’ socio-economic characteristics that determine host communities dependence on forest products. thus, the statistically irrelevant households’ socio-economic characteristics to the model were determined and removed using the automatic linear modelling algorithm. also, if all the categories of a variable significantly influenced the host communities’ dependence on forest products, the algorithm generated a single significant value for the associated variable. thereafter, the statistically relevant households’ socio-economic characteristics were ranked using the computed importance ratio to determine the degree of host communities’ socioeconomic dependence on forest products. the description of the explanatory variables as used in the modelling are stated as follows: age in years (0–4=1, 5–14=2, 15–60=3, above 60=4), sex (male=1, female=2), place of birth (yes=1, no=0), ancestral home (yes=1, no=0), education level (non-formal=1, primary=2, secondary=3, ond/nce=4, hnd/bsc=5, msc/phd=6, others=7), religion (islam=1, christianity=2, traditional worshipping=3, others=4), total monthly income (less than n7, 500=1, n7, 500-n24, 000=2, n24, 000 and above=3) (7) where; yi = forest dependency index βo = constant term β1 to β16 = coefficients relating to the households’ socio-demographic characteristics ei = error term with mean value of 0 x1 = age0 – 4 x2 = age5 – 14 x3 = age15 – 60 x4 = ageabove 60 x5 = house composition of male x6 = household composition of female, x7 = place of birth, x8 = ancestral home, x9 = education level of nonformal, x10 = education level of primary school, x11 = education level of junior/senior high school x12 = education level of bachelor, x13 = education level of masters, x14 = education level of others, x15 = religion, x16 = total monthly income olaniyi et al. /journal of tropical forestry and environment vol. 8, no. 02 (2018) 54-68 59 3. results demographic characteristics of sampled households in the host communities of pendjari national park, benin republic are presented in table 1. table 1: demographic characteristics of sampled households in the host communities of pendjari national park, benin republic. $1 per cfca 603 as at november 2016 characteristics frequency percentage sex male 2,101 49.11 female 2,177 50.89 average household size 11 ± 5 age 0 4 833 19.47 5 14 1,312 30.67 15 60 2,032 47.50 > 60 101 2.36 place of birth inside the village 316 79.00 outside the village 84 21.00 ancestral home current village 350 87.50 not current village 50 12.50 level of education nonformal 2,017 47.15 primary school 1,397 32.66 junior/senior high school 846 19.78 tertiary 18 0.42 religion islam 69 17.25 christianity 226 56.50 traditional worshipping 101 25.25 others 4 1.00 total monthly income less than 22, 615 cfca 68 22.67 22, 615 cfca – 72, 360 cfca 124 41.33 72, 360 cfca and above 108 36.00 occupation farming 310 77.50 tour guiding 6 1.50 teaching 17 4.25 civil service 6 1.50 trading 52 13.00 fishing 8 2.00 herding 1 0.25 60 it was noticed that 2,101 (49.11%) of the sampled household composition were males, while females were 2,177 (50.89%). however, the mean household size was 11±5. household age category (above 60 years) had the least occurrence of 101 (2.36%), while household age category (15–60 years) had the highest occurrence of 2,032 (47.50%). furthermore, it was noticed that 316 (79.00%) of the household heads were born inside the sampled community, while 84 (21.00%) of the household heads were born outside the sampled community. although, 350 (87.50%) of the household heads had their ancestral home situated in the current community, while 50 (12.50%) of the household heads had their ancestral home situated outside the current community. also, 2,017 (47.15%) of the household members had non-formal level of education, 18 (0.42%) of the household members had tertiary education, while none had university postgraduate education. thus, 308 (77.00%) of the households were predominantly involved in the farming occupation. households that are involved in christianity had the highest frequency of 226 (56.50%), followed by traditional worshipping [101 (25.25%)], then islam [69 (17.25%)], while households that are involved in no religion had the least frequency of 4 (1.00%). most of the households had total monthly income of less than 22, 615 cfca [295 (73.75%)], 102 (25.50%) had total monthly income between 22, 615 cfca and 72, 360 cfca while 3 (0.75%) had total monthly income of above 72, 360 cfca. forest dependency indices of host communities to pendjari national park, benin republic are presented in table 2. the data revealed that porga and kolegou communities were the most dependent on food and food additives with dependency index of 100±0.0 each, while tanguieta community was the least dependent on food and food additives with dependency index of 36±45.3. also, it was observed that kani and kolegou communities were the most dependent on fuel with dependency index of 100±0.0 each, while tanguieta community was the least dependent on fuel with dependency index of 60±44.1. moreso, it was observed that kani community was the most dependent on housing with dependency index of 86±5.2, while tanguieta community was the least dependent on housing with dependency index of 22±32.4. the data revealed that porga, tanougou and kolegou communities were the most dependent on trado-medicinal with dependency index of 100±0.0 each, while tounsega community was the least dependent on trado-medicinal with dependency index of 43±24.6. it was observed that sangou community was the most dependent on income with dependency index of 73±42.5, while tanguieta community was the least dependent on income with dependency index of 5±22.1. the data revealed that sangou community were the most dependent on the forest products of pendjari national park with dependency index of 84±9.6, while tanguieta community was the least dependent on the forest products of pendjari national park with dependency index of 39±26.8. determinants of the host communities' socio-economic dependence on forest products of pendjari national park are presented in table 3. the result indicated that the automatic linear modelling method presented five predictors to be determinants to host communities’ socio-economic dependence on forest products. age classes of 0–4years (p=0.05), 5–14years (p=0.00), above 60years (p=0.00), religion (p=0.00), total monthly income (p=0.00), education level of junior/senior high school (p=0.00), bachelor’s degree (p=0.00), place of birth (p=0.00) had significant influence on the forest dependency index of the park. moreover, household members with age group of 5–14years had the highest degree of importance (0.288) to determining host communities’ socio-economic dependence on forest products followed by place of birth (0.174), while household members with non-formal education had the least degree of importance (0.024). olaniyi et al. /journal of tropical forestry and environment vol. 8, no. 02 (2018) 54-68 61 table 2: fores t depen dency indice s of host com munit ies to pendj ari natio nal park, benin repu blic. table 3: determinants of host communities’ socio-economic dependence on forest resources of pendjari national park, benin republic. host communities food and food additives fuel housing medicinal income forest dependency index rankin g daga 55±27.3 65±26.6 84±1.8 61±21.2 24±40.81 58±21.8 10 th porga 100±0.0 89±21.2 81±19.3 100±0.0 46±47.21 83±22.2 2 nd dassari 45±43.6 61±44.6 65±35.7 65±41.1 36±45.27 54±13.2 12 th tounsega 38±25.4 61±33.0 68±24.3 43±24.6 8±18.45 43±23.5 13 th pouri 58±31.4 67±27.3 70±24.8 68±30.5 11±20.49 55±24.6 11 th tiele 81±25.0 78±25.6 81±4.8 97±12.5 11±27.70 70±33.4 8 th wantehoun 56±17.1 63±22.4 85±3.7 72±25.6 63±50.00 68±11.4 9 th kani 84±35.2 100±0.0 86±5.2 76±28.5 22±36.37 74±30.2 6 th nagassega 90±25.5 92±19.0 82±15.3 89±22.3 27±41.65 76±27.5 5 th tanguieta 36±45.3 60±44.1 22±32.4 70±39.1 5±22.07 39±26.8 14 th tanougou 88±33.5 78±33.9 70±28.7 100±0.0 34±51.13 74±25.0 7 th sangou 88±33.6 91±23.6 74±25.8 94±16.8 73±42.47 84±9.6 1 st kolegou 100±0.0 100±0.0 83±0.0 100±0.0 19±40.30 80±35.2 3 rd batia 75±40.8 91±20.2 83±0.0 88±34.2 56±72.70 79±13.8 4 th socio-economic characteristics automatic linear modeling degree of importance coefficients significance importance ratio age (years) 0-4 1.89 0.05* 0.031 8 th 5-14 3.20 0.00* 0.288 1 st 62 above 60 7.55 0.00* 0.077 5 th religion -7.92 0.00* 0.119 4 th total monthly income 7.15 0.00* 0.073 6 th education non–formal 0.73 0.09 ns 0.024 9 th junior/senior high school 1.31 0.01* 0.067 7 th bachelor 22.51 0.00* 0.147 3 rd place of birth 11.13 0.00* 0.174 2 nd constant 10.32 0.10 ns olaniyi et al. /journal of tropical forestry and environment vol. 8, no. 02 (2018) 54-68 63 4. discussion the study revealed that the host communities depended on the forest products at varying degree and different forms. it supported the view of babulo et al. (2008), bwalya (2013) who stated that the importance of forests as a source of livelihood varies geographically, over time and across households. the composition of the sampled host communities’ households in pendjari national park were mostly females. the finding was in consonance with the report of insae (2015) that the proportion of women within the beninese population and atacora department remained practically 51.2% and 50.7% respectively in 2013. but the insignificance of gender in the host communities’ socio-economic dependence on the park negated the assertion of mehta and heinen (2001), that gender remained one of the factors that influenced the perception of host communities on their immediate protected areas. however, the vast majority of the household composition was observed to fall within the age bracket between 15 years and 60 years. it is believed that the host communities of pendjari national park were most active and productive with greater tendency to exert their energy into natural resources exploitation or conservation in the protected area. contrary, the result revealed that the age class had no statistical significance on the host communities’ socio-economic dependence on forest product despite its dominance. the exerted pressure on natural resources of the park emanated from the age classes 5-14 years and above 60 years. this can be attributed to the rural-urban migration-drift by the age category of 15–60 years for education and business purposes, which reflected the inadequacy of basic educational and social amenities towards improving the social and economic well-being of the communities. although, the drift is usually temporary and short-stay in nature because most age group members unite with their households daily or weekend. the international organisation for migration (2011) and blum (2014) corroborated the existence of the rural-urban migration attitude in benin republic among the age group of 15–60 years from rural areas in order to meet their daily needs. their reports revealed an increased number of beninese nationals migrating to other west african countries due to demographic growth, poverty, unemployment, increased living costs, difficult climatic conditions and dwindling natural resources though, no mention of age class of beninese nationals involved. hence, the result was in consonance to the findings of ofoegbu et al. (2017) and igu (2017) who believed that youths depended more on the forests of south africa and niger delta region of nigeria. it implied that the involvement of the older population in the forest products utilisation ensures the park’s sustainability due to the linkage between their adequate knowledge in the forest resources management/utilization and optimal usage of forest products (mamo et al., 2007). household heads’ place of birth played a significant role that determined the socio-economic dependence of host communities on the forest products of the park. most household heads were born inside the host communities, which implied that the provided information could be reliable due to their adequate knowledge and experience of the happenings in their respective communities. much more, the study revealed that majority of the households were illiterate with little or no formal education which fell in line with iucn (2002) report that the literacy rate in pendjari national park is very low. although, no formal education level had no statistically significant influence on host communities’ socio-economic dependence on forest products of the park. despite this, higher education levels such as junior/senior and bachelor’s degree education had a significant influence on the host communities’ forest dependency indices. it supported the assertions of malleson et al. (2014), widianingsih et al. (2016) and fikir et al. (2016) that higher education level of household members played a significant influence on their forest resources dependence in cameroun, ghana, nigeria, indonesia, hammer district of southeastern ethiopia. this implied a higher understanding and alignment to re-orientation of value system through 64 conservation awareness programs as substantiated by mcclanahan et al. (2005) and satyanarayana et al. (2012). this finding contradicted the views of previous authors on the positive link between awareness on the availability of forest products and education (mcclanahan et al., 2005; anthony, 2007). moreover, the majority of the households fell within the poor income group due to their total monthly income below the poverty line limit of less than $1.25 daily. this could affect the dependence of host communities on the park’s forest products which supported the views of bwalya (2013), malleson et al. (2014), ofoegbu et al. (2017) and igu (2017) who observed that household income significantly linked with their likelihood of engaging in forest resources utilisation and management. however, the situation in pendjari national park was such that the planning framework and management strategies employed by the park authority encouraged host communities to gain benefits from the park-cheaper sales from hunters’ and poachers’ kill, free accessibility to non-timber forest products (medicinal plants), cultural integration with tourists for further assistance, access to farmlands, provision of employment (eco-guard, park staff), gifts to schools by foreign tourists, fishing in free zone and pendjari river, food and food additives (such as fodders for animals, food spices, etc), housing materials, and so on. the participatory management strategy allowed the host communities to harvest medicinal plants and tangible fruits from the controlled access and hunting zones, once they received authorization from village associations for the management of wildlife reserves (vodouhe et al., 2010). according to (iucn, 2002) and vodouhe et al. (2010), most of the villages adjacent to the park formed “village associations for the management of wildlife reserves” (avigref), which enabled villagers to participate in decision-making process about the park and to share the benefits from park entry fees for tourism, hunting licenses and fines imposed for illegal activities. much more, some communities had benefitted from other various initiatives of avigref such as the provision of donkey’s cart/trolley, skills training on compost production, repair of boreholes, repair, and supply of chairs/tables, and employment of teachers to schools. this is believed to reduce undue pressure on the forest products of the core area (i.e. pendjari biosphere reserve). population size, urbanisation and proximity of a host community to a protected area could positively influence their socio-economic dependence on forest products (jimoh et al., 2013; zeng et al., 2016; igu, 2017; suleiman et al., 2017; unesco, 2017). this was evident in tanguieta with the lowest dependence on food and food additives, fuel, housing materials, trado-medicinal products, and forest income. indeed, the availability of other alternatives for survivability and improved livelihood such as animal feeds for fodder; gas, kerosene, and charcoal for fuel; various clinics, hospitals, pharmacy, drug stores, few business opportunities could be a better explanation towards their low forest dependence. also, coupled to the fact that tanguieta is strategically located at the park’s periphery along the expressway linking cotonou (the commercial hub of benin republic) and burkina-faso, most households can be socio-economically sustained without forest products from the park. geographical location in terms of close proximity to the park’s boundary and nature of animal husbandry of porga and kolegou communities contributed to their most dependent on food and food additives. however, remoteness of the host communities influenced the overall dependence of each host community on the park’s forest product. 5. conclusion the forest dependency indices revealed that most host communities in pendjari national park were dependent on the park in varied forms and degrees. the determinants of host communities to their socio-economic dependence on forest products of the park were household members’ age, religion, total monthly income, education and household head’s place of birth. despite the households’ socio-economic determinants to forest dependence, downward trend in the perceived availability of forest products over time, and the adopted management strategy in the current planning and management framework which allowed host communities’ involvement and benefit gains from biodiversity conservation in pendjari national park, community advocacy programmes should be initiated to involve relevant stakeholders. olaniyi et al. /journal of tropical forestry and environment vol. 8, no. 02 (2018) 54-68 65 stakeholders such as the authority of reserve de biosphere de la pendjari, community leaders, household heads, youth representatives, market women leader, tour operators and relevant government officials. this initiative becomes necessary in order to identify and prioritise the social and economic needs of each host community. it will provide useful information to improving the livelihoods and well-being of the host communities’ inhabitants. and, the livelihood/well-being improvement can be achieved through forest products’ value addition (i.e. processing, preservation), and provision of alternative means of survival and social amenities (i.e. health centres, accessible roads, market stalls, kerosene and/or gas stations, modern cooking kiln, animal feed sales point, hay and silage production centre, well equipped primary and secondary schools, good transportation system, electricity, subsidy in fertilizer and other agricultural inputs supply, etc). these will provide a template for sustainable development and better co-existence between protected areas and their host communities. acknowledgment the authors appreciate the financial support of the a.g. leventis foundation, zurich, switzerland under grant numbers (5982, 10342, 12108) for the phd program of the corresponding author. also, we appreciate the postdoctoral intellectual platform provided by the third world academy of sciences (twas), italy and universiti putra malaysia (upm), malaysia. our sincere gratitude to the authority of réserve de biosphère de la pendjari, mr. cosme kpadonou and mr. apolinaire for their logistic supports during the data collection stage. references al-subaiee, f.s. (2016). socio-economic factors affecting the conservation of natural woodlands in central riyadh area – saudi arabia. saudi journal of biological sciences, 23: 319–326. anitha, v. and muraleedharan, p.k. 2006. economic valuation of ecotourism development of a recreational site in the natural forests of southern western ghats. kerala forest research institute, peechi – 680 653, thrissur, kerala. anthony, b. (2007). the dual nature of parks: attitudes of neighbouring communities towards kruger national park, south africa. environmental conservation, 34 (3): 236–245. assede, e.p.s., adomou, a.c. and sinsin, b. (2012). magnoliophyta, biosphere reserve of pendjari, atacora province, benin. check list, 8(4): 642–661. babulo, b., muys, b., nega, f., tollens, e., nyssen, j., deckers, j. and mathijs, e. (2008). household livelihood strategies and forest dependence in the highlands of tigray, northern ethiopia. agricultural systems, 98: 147–155. babushrestha, u., dhital, k. and gautam, a. (2017). economic dependence of mountain communities on chinese caterpillar fungus ophiocordyceps sinensis (yarsagumba): a case from western nepal. oryx, 1 – 9. belem, b., nacoulma, b.m.i., gbangou, r., kambou, s., hansen, h.h., gausset, q., lund, s. and blum, c. (2014). cross-border flows between nigeria and benin: what are the challenges for (human) security?. friedrich-ebert-stiftung publication. pp 14. bwalya, s.m. (2013). household dependence on forest income in rural zambia. zambia social science journal, 2(1): 67-86. cenagref, (1997). etude diagnostic des structures de gestion des réserves de faune du bénin antérieures au cenagref. 50 pp. cenagref, 2005. parc national de la pendjari, bénin: plan d'aménagement participative et de gestion 2004–2013. cenagref/gtz, pp83. cenagref, 2016. plan d’ame´nagement et de gestion participatif de la re´serve de biosphe`re de pendjari (2016–2025). pp157. 66 cheke, r. a. (2001). "benin" in fishpool, l.d.c.; evans, m.i. (ed.). important bird areas in africa and associated islands: priority sites for conservation. newbury and cambridge, uk: pisces publications and birdlife international. 93-98. dof, nature kenya, nature uganda and bird conservation nepal, (2014). integrating livelihoods and conservation people partner with nature for sustainable living program 2015-2017. dansk ornitologisk forening. pp 46. fao, 2016. state of the world’s forests. forests and agriculture: land-use challenges and opportunities. rome. pp126 fikir, d., tadesse, w. and gure, a. (2016). economic contribution to local livelihoods and households dependency on dry land forest products in hammer district, southeastern ethiopia. international journal of forestry research, pp11. francis, p., lapin, d. and rossiasco, p. (2011). securing development and peace in the niger delta: a social and conflict analysis for change. washington dc: woodrow wilson international centre for scholars. igu, n. i. (2017). swamp forest use and loss in the niger delta: contextual and underlying issues. open journal of forestry, 7, 34-47. institut national de la statistique et de l’analyse economique (insae), (2015). rgph4: que retenir des effectifs de population en 2013? ministere du developpement, de l’analyse economique et de la prospective, republique du benin. pp35. institut national de la statistique et de l’analyse economique (insae), (2013). résultats provisoires du rgph4. cotonou: insae. institut national de la statistique et de l’analyse economique (insae), (2002). rgph 3: third general census of population and housing. cotonou, pp: 250, (in french). international organisation for migration (iom), (2011). migration au bénin: profile national. available online: http://publications.iom.int/bookstore/free/profil_migratoire_benin.pdf (accessed on 28 january 2014). iucn, 2002. iucn evaluation of nominations of natural and mixed properties to the world heritage list. report to the world heritage committee twenty-sixth session 24–29 june 2002 — budapest, hungary, pp. 9–17. jimoh, s.o. and haruna, e.a. (2007). contributions of non-timber forest products to household food security and income around onigambari forest reserve, oyo state, nigeria. j environ ext, 6(1):28–33. kassa, b., (2008). ecologie, ethologie, utilisation de l’espace et dynamique des populations de waterbuck (kobus ellipsiprymnus defassa) dans la réserve de biosphère de la pendjari, bénin. thèse de doctorat en sciences agronomiques, université d’abomey-calavi, 202p. koenig, j., altman, j. and griffiths, a.d. (2011). artists as harvesters: natural resource use by indigenous wood carvers in central arnhem land, australia. hum. ecol. 39, 407–419. kutner, m. h., nachtsheim, c. j. and neter, j. (2004). applied linear regression models (4th ed.). new york: mcgraw-hill/irwin. lawry, s., mclain, r. and kassa, h. (2015). strengthening the resiliency of dryland forest-based livelihoods in ethiopia and south sudan: a review of literature on the interaction between dryland forests, livelihoods and forest governance. working paper 182. bogor, indonesia: cifor. pp59 lepetu, j., alavalapati, j. and nair, p.k. (2009). forest dependency and its implication for protected areas management: a case study from kasane forest reserve, botswana. international journal of environmental research, 3(4): 525–536. malleson, r., asaha, s., egot, m., kshatriya, m., marshall, e., obeng-okrah, k. and sunderland, t. (2014). non-timber forest products income from forest landscapes of cameroon, ghana and nigeria an incidental or integral contribution to sustaining rural livelihoods? international forestry review, 16(3): 261-277. olaniyi et al. /journal of tropical forestry and environment vol. 8, no. 02 (2018) 54-68 67 mamo, g., sjaastad, e. and vedeld, p. (2007). economic dependence on forest resources: a case from dendi district, ethiopia. forest policy and economics, 9:916-927. mcclanahan, t., davies, j. and maina, j. (2005). factors influencing resource users and managers' perceptions towards marine protected area management in kenya. environmental conservation 32: 42–49. mehta, j.n. and heinen, j.t. (2001). does community-based conservation shape favourable attitudes among locals? an empirical study from nepal. environmental management, 28: 165–177. meijaard, e., abram, n.k., wells, j.a., pellier, a.s., ancrenaz, m., et al, (2013). people’s perceptions about the importance of forests on borneo. plos one 8 (9), e73008. miller, a. j. (2002). subset selection in regression (2nd ed.). new york: crc nago, s.g.a., grell, o., sinsin, b. and rödel, m. (2006). the amphibian fauna of pendjari national park and surroundings, northern benin. salamandra, 42: 93-108. ofoegbu, c., chirwa, p.w., francis, j. and babalola, f.d. (2017). socio-economic factors influencing household dependence on forests and its implication for forest-based climate change interventions. southern forests: a journal of forest science. raebild, a., lampo, d., ouedraogo, m., theilade, i. and boussim, i.j. (2007). use of non-wood forest products by local people bording the “parc national kaboré tambi”, burkina faso. the journal of transdisciplinary environmental studies, 6 (1): 1–14. ratner, b. (2012). statistical and machine-learning data mining: techniques for better predictive modeling and analysis of big data (2nd ed.). boca raton, fl: taylor & francis group. sapkota, i.p. and oden, p.c. (2008). household characteristics and forest dependency on community forests in terai of nepal. international journal of social forestry, 1: 123-144. satyanarayana, b., bhanderi, p., debry, m., maniatis, d., fore´, f., badgie, d., jammeh, k., vanwing, t., farcy, c., koedam, n., dahdouh-guebas, f. (2012). a socio-ecological assessment aiming at improved forest resource management and sustainable ecotourism development in the mangroves of tanbi wetland national park, the gambia, west africa. ambio. 41:513–526. shibia, m.g. (2010). determinants of attitudes and perceptions on resource use and management of marsabit national reserve, kenya. journal of human ecology, 30: 55-62. sogbohossou, e.a., bauer, h., loveridge, a., funston, p.j., de snoo, g.r., sinsin, b. and de longh, h.h. (2014). social structure of lions (panthera leo) is affected by management in pendjari biosphere reserve, benin. plos one, 9(1): e84674. songorwa, a.n. (1999). community-based wildlife management (cwm) in tanzania: are the communities interested? world, 27 (12), 2061–2079. thondhlana, g., vedeld, p. and shackleton, s. (2012). natural resource use, income and dependence among san and mier communities bordering kgalagadi transfrontier park, southern kalahari, south africa. international journal of sustainable development and world ecology, 19(5): 460– 470. tieguhong, j.c. and nkamgnia, e.m. (2012). household dependence on forests around lobeke national park, cameroon. international forestry review, 14(2): 196–212. tiomoko, d.a. (2007). impacts des recettes de la chasse safari sur la conservation participative de la réserve de biosphère de la pendjari. université d'abomey-calavi; faculté des lettres arts et sciences humaines, mémoire de dea. 41 pp. unesco, (2013). biosphere reserves-learning sites for sustainable development. http://www.unesco.org/new/en/natural-sciences/environment/ecological-sciences/biospherereserves. unesco, (2017). forest management and the impact on water resources: a review of 13 countries. edited by pablo a. garcia-chevesich, daniel g. neary, david f. scott, richard g. benyon, teresa reyna. pp197. 68 vedeld, p., angelsen, a., bojö, j., sjaastad, e. and kobugabe, b.g. (2007). forest environmental incomes and the rural poor. forest policy and economics, 9: 869–879. vodouhê, f.g., coulibaly, o., adégbidi, a. and sinsin, b. (2010). community perception of biodiversity conservation within protected areas in benin. forest policy and economics, 12: 505–512. weisberg, s. (2005). applied linear regression (3rd ed.). hoboken, nj: john wiley & sons, inc. widianingsih, n.n., theilade, i. and pouliot, m. (2016). contribution of forest restoration to rural livelihoods and household income in indonesia. sustainability, 8(835): 1–22. yamane, t. (1967). statistics: an introductory analysis, 2nd ed., new york: harper and row. yan, x. and su, x. g. (2009). linear regression analysis: theory and computing. singapore: world scientific. yang, h. (2013). the case for being automatic: introducing the automatic linear modeling (linear) procedure in spss statistics. multiple linear regression viewpoints, 39(2): 1 – 37. zeng, c., deng, x., dong, j. and hu, p. (2016). urbanization and sustainability: comparison of the processes in “bic” countries. sustainability, 8: 400. _____________________________________________ *correspondence: drsourabhdeb@gmail.com © university of sri jayewardenepura 26 management regimes, soil properties and carbon stock in community managed forests d. deb, s. deb* and j. debbarma department of forestry and biodiversity, tripura university, suryamaninagar, tripura, india date received: 10-07-2019 date accepted: 10-12-2020 abstract the study was carried out to understand the management strategies, soil nutrient properties and carbon sock of community managed forests practiced by jamatia community of tripura, northeast india. it revealed that jamatia people of tripura are actively involved in conservation and management of the forests under their control. the concept of creating forest and follow an institutional setup for management of forest resources are being noted in this ethnic community. in community forests, maximum numbers of individuals of tree species were represented from the lower girth class while individuals from higher girth class contributed larger biomass and carbon. anogeissus acuminata was the most preferred species in the community forest as it is the source of timber and fuel wood and also contributing high biomass among other species. the total biomass and carbon stock in the community managed forest was found as 40.66 tha-1 and 20.33 tha-1 respectively. the soil of community forests are very fertile and found acidic in nature. the mean soc is 1.38%, whereas available nitrogen and phosphorus content are 210.79 kg ha-1and 8.36 kg ha-1 respectively. however, a positive and significant correlation of available phosphorus was observed with physical properties like soil temperature, ph and also with total nitrogen content. these forests have potential for future carbon sequestration and to mitigate climate change for longer run as it is managed sustainably by the community. keywords: biodiversity, biomass, conservation, institution, jamatia community, tradition 1. introduction human beings have been relied on forests since long period of time not only for their livelihoods, but also as an integral element in their cultural, spiritual and social systems. chatterjee et al. (2000) mentioned that the forest provides innumerable tangible and intangible benefits, and its judicious utilisation provides us a sustainable resource. it is proved that the management approaches has improved the condition of forest and enhanced the livelihood of local people (agarwal and ostrom, 2001). there is great variability in their management practice, which has evolved under different biophysical and cultural environments (nongkynrih, 2001). northeast india is a mosaic of diverse ecological, social and physiological landscapes. the community conserved areas (cca) of north-east indian states were studied by different authors across the regions viz., assam (medhi and borthakur, 2013), meghalaya (kharkongor and tiwari, 2015), manipur (khumbongmayu et al., 2005) and arunachal pradesh (murtem and chaudhry, 2014) and tripura (darlong and barik, 2006). this system was stressed to have deeper level of understanding with proper documentation of its traditional knowledge which needs to be recognised. the ethnic people of this region, through long-term trial and error experiments, have developed an elaborate, functional and democratic system of conservation and management of forests and associated natural ecosystems (tiwari et al., 2013). deb et al./ journal of tropical forestry and environment vol. 10 no. 02 (2020) 26-38 27 there is a critical need to understand the ecological and economical potentiality of community managed forests and accordingly strategise conservation of the forests for future generations. therefore, community conserved areas needs more intensive analyses and conservation. however, there is a lack of scientific research regarding the management practices and other pattern of ownership of community forest, which is very complex and diverse as observed by tiwari et al. (2010). it was reported that the tropical forests contributes around 37% of carbon out of the total 90% terrestrial carbon (houghton, 1996). due to anthropogenic activity it has now become a source of carbon in atmosphere (chhabra and dadhwal, 2004). unfccc has recommended in reducing the limit of emission for stabilising the atmospheric greenhouse gases (unfccc 1993). the role of community forests in carbon stock enhancement and soil management is not known. it is known that the management strategies in a disturbed forest can potentially meet the current need of stabilising the global warming through soil and carbon management. the community based forest management provides an opportunity to build a sustainable link with ecology to meet future needs. this study aims to document management regimes of community forests practiced by jamatia and to quantify carbon pool and soil nutrient status in community managed forest areas of tripura, northeast india. 2. materials and methods 2.1 study area tripura is, one of the land-locked northeastern states in india, situated between the latitudes of 22°56/ n 24°32/ n and the longitudes of 90°09/ e 92°10/ e. with an area of 10,492 km2, the state is the third smallest of the country, covers 0.32% of the country’s geographical area. the primary sector of the state consists of forestry and agriculture. the present study was conducted in killa block of gomati district in tripura (figure 1). this block is mainly inhabited by jamatia community, with combination of debbarma, molsom and other ethnic communities. in total, four villages were selected for the present study viz., wajiy bachai, warung, kaipeng bulai and tairupa bari. it extends between 23°35/28.67// e 91°29/33.6// n to 23°36/43.97// e 23° 57/01.11// e with an average elevation of 68 m amsl. figure 1. map of the study area. 28 2.2 methodology the primary data was collected using standard questionnaire method from the households of four different villages during 2016-2017. some secondary informations were also collected from the head of the local institution. the random sampling method was used, targeting households from each village. information on literacy, economy, sex ratio, occupation, age structure, fuel and fodder dependency and domestic production were also collected. soil samples were collected using soil corer for estimation of physico-chemical properties of soil. the samples were collected from two quadrats from each village up to 1 m depth viz., 0-15, 15-30, 30-45 and 45-100. the soil samples were collected in an air tight zipper bag with proper labeling. a composite sample for each depth was prepared by mixing soils, resulting in one sample per depth level from each study plot for laboratory analyses. soil texture and water holding capacity were determined according to anderson and ingram (1993), while soil moisture content was measured gravimetrically by drying 10 g of field moist soil sample in a hot-air oven at 105° c for 24 h. soil organic carbon was estimated using wet digestion method (walkley and black, 1934). soil available phosphorous was determined calorimetrically by bray and kurtz (1945). total nitrogen was estimated following semi-micro kjeldahl procedure by aciddigestion, distillation and titration (kjeldahl, 1883). the ph of the soil sample was determined in a soilwater suspension (1:2.5 w/v h2o) using a digital ph meter. tree species in the community forest were measured using randomly placed quadrats of 31.6×31.6 m. at each quadrat, height of all woody species with >5cm dbh and diameter at breast height (dbh) were recorded. the species were identified, mostly through their vernacular names and existing literature (deb 1981/1983). biomass and carbon stock was estimated using allometric equation following chambers et al. (2001): exp [-0.37+0.333×ln (d)+0.933×ln (d2)-0.122×ln (d3)] for aboveground biomass and cairns et al. (1997): [exp (-1.059+0.884×ln (agb)+0.284)] for belowground biomass. the total biomass is the summation of above and belowground biomass, carbon was considered 50% of the total biomass following brown et al. (1989). the statistical analysis was performed using statistical tools. the software used was spss 18. 3. results 3.1 management implication there has been a long tradition of community based forest management by the jamatia community in the hilly regions of tripura. four villages were studied (table 1) to recognise the management strategies of community forest by jamatia community in killa block of tripura. the total forest area managed by this indigenous community is 216 ha (excluding the reserved forest). this is a hilly, partly hilly and plain area with an elevation ranging from 52 to 88 m amsl. various forest types like mixed forest, mixed forest with rubber and very dense forest were found. the common species like ailanthus excelsa, bauhinia purpurea, diospyros sp., microcos paniculata, phyllanthus emblica, schima wallichi, syzigium cumini, tectona grandis, terminalia bellerica, terminalia chebula were dominant in the study sites. hevea brasiliensis was also raised in the plantation plot. these forests are mainly managed by the local ethnic people of the area. the management activity starts from beginning of the rainy season i.e., from march till the end of november. the management strategy combines to fulfill the objective of conservation as well the overall development of the community. deb et al./ journal of tropical forestry and environment vol. 10 no. 02 (2020) 26-38 29 table 1: details of community managed forests in tripura. 3.2 institutional arrangement it was found that the community forest is guarded and administered by the local people of the respective villages. each village is lead by the chief called as chowdhuri of the community of a particular village. the chief is assisted by the baya chowdhuri, who is selected by the chief himself and after the consent of the local people. chowdhuri and baya chowdhuri are supported by other members, such as secretary, cashier and other executive members (figure 2). these executive members are representatives from these four villages. for proper management of the community forests, a group of few members belonging to one or two families from each village are selected. these groups alternatively are involved in management and guarding their respective community forests. any major or minor decision for the interest of the people in connection with the community forest is taken after prior permission from the chief and his selected executive members. the chief who is the chowdhuri of the village has the absolute authority for decision making in the group or in any family issue. he is also the supreme head of the village council. he usually presides over any issue raised by the individual or by any group of people. he settles over any issue, if any rights of the community people are violated in any way by any person. he also assists in settling an issue related to any kind of theft of resources from the forest has been reported by the local people. in such case, the guilty is bound to negotiate by paying fine of an amount equivalent to the theft done. immediate to the chowdhuri, baya chowdhuri takes the place. he acts on behalf of the choudhuri in his absence and manage over any issue to a solution. in his presence, he assists the chief for any decision and action. the secretary help to villages wajiy bachai warung tairupa bari kaipeng bfulai community forest total area (ha) 120 16 40 40 elevation (m) 88 52 63 70 topography type hilly hilly partly hill partly hill forest type mixed forest with rubber mixed forest mixed forest very dense forest dominant species bambusa hevea,tectona diospyros syzygium, microcos bauhinia, terminalia sp. schima albizzia sp. bauhinia sp. microcos sterculia diospyros tectona anogeissus schima microcos anogeissus holarrhena banulai caryota flacourtia bamboo sp. management practice season of management march-november march-october march-october march-october establishment status old recent very old old income/year highly profitable minor minor profitable families involved (no.) 72 53 216 145 30 maintain the official record and assists the baya chowdhuri for any decision in the absence of the chief. the cashier takes charges of all the financial matters. he is responsible to collect either monthly or yearly fees to be given by each village. these fund are being utilised for the welfare of the local people such as construction of primary schools, leashing of money to needy ones with low interest rates and during an annual feast that they celebrate in their respective villages. figure 2. institutional set up for management of community forest. a group of 5 to 6 members from each of these four villages are alternatively given charges for traversing their respective community forests mainly in the peak season of probable theft. they help in the proper supervision of the community rules formed for the conservation of the forest. these groups take the responsibility in guarding the forest by an alternative traversing around the forests especially for any illegal activities such as felling and selling of logs and timbers. 3.3 utilisation pattern the utilisation of forest resources by the local people is enormous as the daily needs are fairly fulfilled. they use mainly for fuelwood, fodder, timber, medicinal uses, vegetables and fruits. the excess is used for income generating by selling in the nearby local market. trees were felled as logs after maturity; some important timber species like tectona grandis, anogeissus sp., and bamboos were also harvested for various uses; mainly for selling which are being utilised for construction and furniture making. various dead wood timber species are also converted to planks for fuelwood and other purposes (pillar, posts and other household purposes). bamboo shoots are widely extracted for self-consumption and also for selling, which is highly profitable. however, there is restriction in the extraction of bamboo shoots from the same deb et al./ journal of tropical forestry and environment vol. 10 no. 02 (2020) 26-38 31 area. therefore, the extraction procedure is followed in a patch wise, which enables the shoots to regenerate in a sustainable way. thus, community based forest management offers an alternate approach to sustain the forest resources through the integration of knowledge and skills. this kind of management depends on the community people and their commitment on the conservation and sustainable utilisation. the fuelwood collection and fodder collection is permitted in these areas after prior permission from the chowdhuri or baya chowdhuri of their respective villages. the community people has devised for equitable benefits by giving preference to the neediest groups. thus most of the local poor families are given access to collect fuelwood and extract timber for their own purpose. some multipurpose tree species like albizzia lebbeck is commonly utilised for timber in construction or as fuelwood, whereas bauhinia purpurea is used both as timber and for dyeing. tree species like dillenia indica, garcinia cowa, phyllanthus emblica and other highly nutritive species are found which are used for consumption and for selling in the market for altering their crisis and meeting their needs. in addition, restrictions are given in case of felling of young woody species and extraction of newly regenerating bamboo shoots. therefore, only mature dead wood trees could be felled after granting permission from the chowdhuri or baya chowdhuri. table 2 shows the list of documented multipurpose tree species recorded in these community managed forests. further, there are restrictions on the collection of resources from the community forest from each village. the people from other village cannot collect resources other than their own forests and if anyone is found guilty in collection of resources from other forests, he or she is bound to pay fees or give back the resources collected. table 2. list of species documented in the community managed forest of tripura. botanical name vernacular name family uses ailanthus excelsa roxb. rongeen meliaceae timber, fuelwood albizzia lebbeck (l.) benth. karai mimosaceae timber, insecticide alstonia scholaris (l.) r.br. shatim apocynaceae timber, fuelwood anogeissus sp. boroswrwi combretaceae timber artrocarpus heterophylus lamk kathal moraceae fuelwood, edible bauhinia purpurea (l.) debkanchan caesalpiniaceae dyes, timber bombax ceiba (l.) seemul bombaceae cotton, medicinal callicarpa arborea roxb. barmala verbenacea medicinal caryota urens (l.) swmal arecaceae fuelwood dillenia indica (l.) chalta dilleniaceae edible, timber, medicinal diospyros sp. vanghab ebenaceae timber, fish poison flacourtia jangomas (lour.) raeosch paniyala flaccourtiaceae fuelwood, timber ficus sp. khiychang clusiaceae fuelwood, edible hevea brasiliensis (wild. ex a. juss) mull. arg. rubber euphorbiaceae timber, fuelwood holarrhena antidysentrica flem kurchi apocynaceae medicinal, dyes garcinia cowa roxb. koksika edible mallotus philippensis h. karst kamala euphorbiaceae edible, medicinal 32 microcos paniculata l. pisla tiliaceae fuelwood phyllanthus emblica l. amlaki euphorbiaceae edible, medicinal botanical name vernacular name family uses schima wallichii (dc.) kothals kanak theaceae timber, fuelwood shorea robusta gaertn.f. sal dipterocarpaceae timber, fuelwood sterculia urens roxb. udal sterculiaceae edible, fuelwood syzygium cumini (l.) skeels jamun myrtaceae edible, fuelwood, medicinal tectona grandis l.f. teak verbenaceae timber terminalia bellerica (gaertn.) roxb. bahera combretaceae timber, fuelwood, medicinal terminalia chebula retz. hartaki combretaceae edible, medicinal toona ciliata m. roem. rongeen meliaceae timber vitex negundo l. nishinda verbenaceae medicinal, timber 3.4 soil physico-chemical properties various physico-chemical properties of soil in community managed forests were analysed (table 3). the average soil temperature was 26.05±1.42o c and was in decreasing trend towards the lower depth. however, the soil moisture content was highest in the lower layer with 15.82% with an average value of 11.43%. the value shows increasing trend in the lower depths. the soil bulk density shows the compactness of soil. the values recorded are 1.34 gcm-3 and 1.82 gcm-3 in 30-45 cm and 0-15 cm respectively. considerably, soil porosity was also found to be large in the upper soil layer than lower layer. the maximum soil water holding capacity was in the 30-45 cm soil depth (47.44%) as compared to upper layer of soil (38.88%). table 3. soil physico-chemical properties in community managed forests of tripura. parameters/soil depth 0-15 (mean±se) 15-30 (mean±se) 30-45 (mean±se) 45-100 (mean±se) average value soil temp. (o c) 28.63±1.41 27.10±1.05 2 6.48±1.09 22.00±0.05 26.05±1.42 moisture content (%) 8.51±2.19 9.58±2.14 11.81±2.37 15.82±1.99 11.43±1.62 bulk density (g/cm3) 1.82±0.30 1.44±0.16 1.34±0.10 1.55±0.04 1.54±0.10 porosity 0.31±0.11 0.46±0.06 0.49±0.04 0.42±0.01 0.42±0.04 water holding capacity (%) 38.88±3.36 40.52±2.75 47.44±2.91 41.88±2.62 42.18±1.86 ph 5.75±0.07 5.68±0.03 5.68±0.07 5.62±0.08 5.68±0.03 organic carbon (%) 1.43±0.19 1.54±0.14 1.35±0.15 1.18±0.13 1.38±0.08 organic matter (%) 3.21±0.44 3.45±0.31 3.02±0.34 2.64±0.29 3.08±0.17 total kjeldahl nitrogen (%) 1.11±0.14 1.04±0.07 1.05±0.03 0.94±0.02 1.04±0.04 available nitrogen (kg ha-1) 202.50±2.10 207.87±1.33 235.20±2.79 197.57±1.51 210.79±8.41 available phosphorus (kg ha-1) 8.59±0.9 10.77±0.40 3.82±0.83 10.27±0.16 8.36±0.58 deb et al./ journal of tropical forestry and environment vol. 10 no. 02 (2020) 26-38 33 the soil ph is recorded acidic in all sites with an average of 5.68. the lower soil depth (45-100 cm) was, however, found more acidic (5.62) than the upper layers. the soil organic carbon (%) value ranged from 1.18-1.54%. the average of total kjeldahl nitrogen was 1.04% with values ranging from 0.94 to 1.11. the available nitrogen was found highest (235.20 kg ha-1) in 30-45cm soil depth with an average of 210.79 kg ha-1. the soil available phosphorus ranged between 3.82 to 10.77 kg ha-1. the correlation matrix shows that soil porosity and soil bulk density are negatively correlated (r=0.998; p=0.01), whereas a positive and significant correlation of available phosphorus was observed with soil temperature (r=0.980, p=0.05) and ph (r=0.974, p=0.05). 3.5 biomass and carbon stock the vegetational composition in community forest shows that tree individuals are more in 6-25 cm girth class, whereas only 7% and 9% of the total individual is found under 46-65 cm and <5 cm class respectively (figure 3). the total biomass stock in the community managed forest was found as 40.66 tha1 and the carbon content was 20.33 tha-1. the aboveground biomass (27.06 tha-1) was 66.55% of total biomass and the rest 33.45% was belowground biomass (13.60 tha-1). the aboveground biomass ranged from 0.003 tha-1 to 14.49 tha-1, whereas belowground biomass varied from 0.003 tha-1 to 6.895 tha-1. the biomass and carbon storage in the top ten tree species is listed in figure 4 with its total biomass (aboveground and belowground) and carbon content. the carbon content in different species found in community forests are ranging between 0.003 (flacourtia jangomas) tha-1 and 10.694 tha-1 (anogeissus acuminata). the species with highest biomass and carbon content in this community managed forests includes anogeissus acuminata, schima wallichii, tectona grandis, syzygium cumini, ficus sp., holarrhena antidysentrica, diospyrous sp., mallotus phillippensis, bauhinia sp., toona ciliata, among others. figure 3. girth class distribution of tree individuals in community managed forest. 0 10 20 30 40 50 60 <5 6-25 26-45 46-65 66-85 >85 n o . o f in d iv id u a ls girth class (cm) 34 figure 4. biomass and carbon in different species. figure 5 shows the distribution pattern of biomass and carbon stock in different girth classes of community managed forest in tripura. it depicts higher girth class (>85 cm) contributing higher biomass and carbon as compared to other girth classes. however, the number of individuals in lower girth class of 6-25 cm was more as compared to higher girth class. 0 5 10 15 20 25 t o ta l b io m a ss a n d c a rb o n ( t /h a ) a b o v e g ro u n d a n d b e lo w g ro u n d b io m a ss ( t /h a ) species agb /ha bgb /ha tc /ha tb /ha deb et al./ journal of tropical forestry and environment vol. 10 no. 02 (2020) 26-38 35 figure 5. biomass and carbon contribution by different girth class of community managed forests. 4. discussion 4.1 management implication in community forest it is revealed that the community forests of jamatia at killa block is sustainably managed by the community. it is prevalent through the strong institutional set up made up by the indigenous people to manage the social issues along with village customary laws and rules to conserve the forests. the community forest management practice of jamatia community was also reported ealier by darlong and barik (2006). the traditional institutional setup was earlier called “hoda” and the head of the “hoda” was known as the “hoda okra”, meaning head priest and supreme community leader. the management involved the participation of the ethnic people by local traversing of the forest for checking any disturbances in the forests. further the fees paid either monthly and yearly give them the sense of belonging and encourage them to feel the forests as their own. the same kind of study was highlighted in the study done by maharanjan (1998) in dhankuta district of nepal where the participation of marginalised forest user groups are given importance to access the forest products. the access to resources by the people in a sustainable way makes them aware of the need to conserve more of the locally available resources. according to the rule, forest resources like ntfps (bamboo shoots, wild fruits, medicinal plants, fuelwood, fodder and thatch grasses) are collected for bonafide use of the people living under the territorial jurisdiction of those traditional institutions only. this restricts the over-exploitation of resources and put an equal distribution of resources. in fact, forest resources could not be exploited without the prior permission from the traditional authority. this ensures equitable sharing as well as sustainable availability of the resources. collection of timber is also allowed for domestic use to the poor households with prior permission from the traditional institution. the concept of community forestry has gained much popularity because of its successful conservation, utilisation, management and development of forest resources. their institutional set up is more convenient than those modern based institutions as it directly involve the participation of the village people. the funds collected are wisely inclined towards the welfare of the society especially the needy ones through flow of fund during marriage or death or during any emergency. sushenjit and priya (2014) also emphasised on the direct relation of the household characteristics in 0 5 10 15 20 25 30 35 <5 6-25 26-45 46-65 66-85 >85 b io m a ss a n d c a rb o n t /h a girth class (cm) total biomass total carbon 36 defining the provisions subjected towards the local needy ones with low level of education. this allows them to provide incentives in terms of cash or kind and special access to forest reserves which overall check the security of the participation of the local people. during the time of field study, the spirit to conserve the community forest was seen at high stage which is highlighted towards the sense of their own property as they are the custodians of the forest and its resources. however, some constraints still exists in the village but most of the people have taken the role to conserve the forest. their beliefs, thoughts, faiths and worship have positive interaction with the nature. likewise, it is being believed that some devils or ill-hearted person presented in those dense forest. so, to alter such kind of problems they take some protective measures simply known as mudra. this is placed inside the boundary of the village for their protection. this is still practiced and is the most common practice in this ethnic community. 4.2 soil characteristics and carbon stock soil physical properties revealed changes according to soil depth in community managed forests. the decreasing trend in the soil temperature across the depth was observed in all the studied sites. this is due to the fact that upper layer of soil are exposed to high atmospheric temperature. the soil moisture content of the community forest was found higher towards the lower depth of soil. nonetheless, higher soil moisture content recorded in the lower depth might be ascribed to greater clay deposition and humus content. the bulk density value upto 1.82 g cm-³ is comparable with reports from natural forest of bangladesh (kibria and saha, 2011) and from pine forests of meghalaya (tripathy et al., 2009). the soil water holding capacity is an essential characteristic of soil physical properties. in the present report it was found higher in the lower soil depth as compared to upper depth. this is because the lower depth has high bulk density, low porosity and thereby higher water content. the ph was found more acidic in lower soil depth. decreasing ph value with depth may be because of the fact that nutrient availability decreases with depth. the ph value 5.50-5.75 in the community forest of tripura, which is within the ranges as reported in the pine forest of meghalaya (tripathy et al., 2009) and the same pattern was also reported by khanal et al. (2016) in community forest of palpa districts in nepal. except upper soil, the results indicated that with increase in soil depth, bulk density was found to be in increasing trend while the soc was found to be in decreasing trend. the number of individuals was observed higher in 6-25 cm girth class as compared to other girth classes. it indicates the new regeneration coming up in the community forest with high anthropogenic disturbances. this also signifies on the need to allow the new regenerations to come up in order to reestablish the stocking of the forest. the quantification of carbon in different girth classes however shows increasing trend across the higher girth class. this is because larger tree has more biomass despite lower girth class having more number of individuals. the total biomass stock in the present study was recorded as 40.66 tha-1 and the carbon content was 20.33 tha-1, which was quite higher than the dipterocarpous forest of manipur, where 21.92 t/ha and 18.28 t/ha reported in two different sites (devi and yadava, 2015). the present study is comparable with the carbon stock of hannang forest, tanzania (swai et al., 2014) and found higher than the miombo woodlands (19.2 t/ha) of tanzania (munishi et al., 2010). the above ground biomass recorded in different management regimes of garo hills in meghalaya ranges from 204.15 mg/ha to 314.02 mg/ha (upadhaya et al., 2015), 92.08 tha-1 to 276.02 tha-1 in community forests of terai, nepal (mandal et al., 2016) which were found quite higher than the present study. this may be because the studies were done in larger area as compared to the present area. anogeissus acuminata, schima wallichii and tectona grandis were found to have higher biomass as compared to other species. this species are mostly used by the local people in meeting the timber and fuelwood demand for their household construction purposes. hence could be encouraged to maintain the regeneration of these species for meeting the future needs. deb et al./ journal of tropical forestry and environment vol. 10 no. 02 (2020) 26-38 37 5. conclusions the present study shows that jamatia people of tripura are actively involved in conservation and management of the forests under their control. the concept of creating forest and settling aside forest patches for forest supply revenue within a territorial jurisdiction of the traditional institutions are being noted in this community. the active participation of the community people also encourages them to conserve the resources available to them. the biomass and carbon contribution of community managed forests are much higher than other land use systems. few plants like anogeissus acuminatea, schima wallichii are important tree species in the community managed forest and stored good amount of carbon in the system. the impact of community managed forest also has significant improvement in soil qualities due to long time management practices. henceforth, the study has demonstrated that community forest is having the potential to mitigate climate change for longer run through the sequestration of atmospheric c to soil and vegetation and by acting as a natural carbon sink. thus, this kind of community approaches could be replicated for the management and conservation of any degraded system. acknowledgement the authors are thankful to department of science and technology, government of india, new delhi, india for providing financial support (dst/is-stace/co2-sr-230/14 (g)-aicp-afolu-vii) to conduct field study in tripura. references agarwal, a. and ostrom, e., 2001. collective action, property rights, and decentralization in resource use in india and nepal. politics and society, 29:485-514. anderson, j.m. and ingram, j.s.i., 1993. tropical soil biology and fertility-a handbook of methods. 2nd edn. cab international, wallingford, uk. bray, r.h. and kurtz, l.t., 1945. determination of total organic and available forms of phosphorus in soils. soil science, 59:39-46. brown, s., gillespie, a.j.r. and lugo a.e., 1989. biomass estimation methods for tropical forests with applications to forest inventory data. forest science, 35:881-902. cairns, m.a., brown, s., helmer, e.h. and baumgardner, g.a., 1997. root biomass allocation in the world's upland forests. oecologia, 111:1-11. chambers, j.q., santosdos, j., riberio, r.j. and highuchi, n., 2001. tree damage, allometric relationships and aboveground net primary production in central amazon forest. forest ecology and management, 152:73-84. chatterjee, s., ghosh, s., sarma, j., barik, s.k., tewari, b.k. and das, k.c., 2009. community conserved areas in north east india: some observations in assam, meghalaya and arunachal pradesh. http://www.kalpavriksh.org/images/cca/miscellaneous/indiarep_ccas%20north%20east%20 india_20%20july_2009[1].pdf. accessed 7 december 2018. chhabra, a., palria, s. and dadhwal, v.k., 2002. growing stock-based forest biomass estimate for india. biomass bioenergy, 22:187-194. darlong, v.t. and barik, s.k., 2006. forests of hope: the jamatias of killa district , tripura. pp. 40-49 in: poffenbenger m, barik sk, choudhury d, darlong v, gupta v, palit s, roy i, singh i, tiwari bk, upadhyay s (background paper no 12) forest sector review of northeast india. community forest international, santa barba, usa. deb, d.b., 1981, 1983. the flora of tripura state vols. i & ii. today & tomorrow printers & publishers, new delhi. 38 devi, l.s. and yadava, p.s., 2015. carbon stock and rate of carbon sequestration in dipterocarpus forests of manipur, northeast india. journal of forestry research, 26:315-322. houghton, r.a., 1996. land-use change and terrestrial carbon: the temporal record. in: apps mj, price dt (ed.) forest ecosystems, forest management and the global carbon cycle. springer-verlag, berlin, heidelberg, new york. khanal, y., sharma, r.p. and upadhyaya, c.p., 2010. soil and vegetation carbon pools in two community forests of palpa district, nepal. banko janakari. 20:34-40. kharkongor, b.m. and tiwari, b.k., 2015. sacred groves of meghalaya: a review. international journal of science and research, 6:346-349. khumbongmayu, a., khan m.l. and tripathi r.s., 2005. sacred groves of manipur, northeast india: biodiversity value, status and strategies for their conservation. biodiversity conservation, 14:15411582. kibria m.g. and saha, n., 2011. analysis of existing agroforestry practices in madhupur sal forest: an assessment based on ecological and economic perspectives. journal of forestry research, 22:533542. kumar, p., 2008. carbon sequestration strategy of nubra valley with special reference to agroforestry. drdo technology spectrum, pp. 187-192. maharanjan, m.r., 1998. flow and distribution of costs and benefits in the chuliban community forest, dhankuta district, nepal. rural development forestry network paper 23e. odi, pp 1-12. mandal, r.a., dutta, i.c., jha, p.k. and karmacharya, s.b., 2016. carbon sequestration potential in community and collaborative forests in terai, nepal. tropical ecology, 57:655-662. medhi, p. and borthakur, s.k., 2013. sacred groves and sacred plants of the dimasas of north cachar hills of northeast india. african journal of plant sciences, 7:67-77. munishi, p.k.t., mringi, s., shirima, d.d. and linda, s.k., 2010. the role of the miombo woodlands of the southern highlands of tanzania as carbon sinks. journal of ecology and the natural environment, 2:261-269. murtem, g., chaudhry, p., 2014. sacred groves of arunachal pradesh: traditional way of biodiversity conservation in eastern himalaya of india. indian journal on biodiversity management forestry, 3:2. nongkynrih a.k., 2001. ka shnong the microcosm of hynniewtrep society. lndian horizon 48:121-151. swai, g., ndangalasi, h.j., munishi, p.k. and shirima, d.d., 2014. carbon stocks of hanang forest, tanzania: an implication for climate mitigation. journal of ecology and the natural environment, 6:90-98. tiwari, b.k., tynsong, h. and lynser m.b., 2010. forest management practices of the tribal people of meghalaya, north-east india. journal of tropical forestry, 22:329-342. tiwari b.k., tynsong, h., lynrah, m.m., lapsam, e., deb, s. and sharma, d., 2013. institutional arrangement and typology of community forests of meghalaya, mizoram and nagaland of northeast india. journal of forestry research, 24:179-186. tripathy k.p. and singh, b., 2009. species diversity and vegetation structure across various strata in natural and plantation forests in katerniaghat wildlife sanctuary, north india. tropical ecology, 50:191-200. unfccc. 1993. the united framework convention on climate change. un. upadhaya, k., thapa, n. and barik, s.k., 2015. tree diversity and biomass of tropical forests under two management regimes in garo hills of north-eastern india. tropical ecology, 56:257-268. walkley, a. and black, i.a. 1934. an examination of degtjareff method for determining soil organic matter and a proposed modification of the chromic acid titration method. soil science, 37:29-37. chapter five: discussion 60 determination of the effectiveness of hal bark (vateria copallifera) as a natural preservative for food security of confectionery industry s.b. navaratne * department of food science and technology, university of sri jayewardenepura, sri lanka date received: 25-11-2015 date accepted: 05-12-2015 abstract hal (vateria copallifera) bark can be used to control sugar fermentation process by yeast. therefore, it was subjected to sun, mechanical, shade and cooling with dehumidified (cd) drying processes in order to identify the best drying method. 1.5 g of dried bark from four drying processes were introduced into four, 40% sugar (sucrose) solutions to identify the best drying method in terms of froth formation. in addition, 1.5 g of hal bark was introduced into 30%, 40%, 50% and 60% sugar solutions to determine at what sugar concentration that hal bark is capable to control sugar fermentation. moreover, 0.5, 1.0, 1.5, 2.0 and 3.0 g of bark from the best drying method were introduced into 50% sucrose solutions to determine the level that hal bark can be incorporated into sugar solutions without changing the sugar taste. finally, optimum level of hal bark was introduced into 50% sugar solution and levels of reducing, non-reducing and total sugars against the control were monitored. sugar solutions were inoculated with 1.0% yeast. the best drying method was cd as it was capable to control sugar fermentation at 40% sugar level and others had it at 50% level. sensory evaluation revealed that up to 1.0 g of hal bark can be incorporated into 100 ml of sugar solutions without disturbing to the sugar taste. while 1 g of hal bark was capable to control sugar fermentation at 50% sugar level, control had same performance at 60%. 1.2 g of hal bark from the best drying method in 50% sugar solution was capable to maintain reducing, non-reducing and total sugars unchanged against the control. keywords: vateria copallifera, copalliferol, reducing sugar, non-reducing sugar, hal bark 1. introduction hal (vateria copallifera) tree is native to sri lanka and its bark has been used for long time by rural folk in some areas of the country as an age old practice to prevent sugar–yeast fermentation process in treacle (dassanayaka and forberg, 1980). as this plant is widely available in the natural habitats of south west region, particularly on the hill sides and the river banks of the country, peasants in these areas incorporate a small piece of this bark to the treacle just after accomplishment of the boiling process of the sap water of kitul (caryota urens) or coconut (cocos nucifera) (kostermans, 1982). as yeast govern fermentation process of the treacle badly affecting to its keeping quality as well as to its organoleptic properties, the domestic scale producers have discovered that hal bark is the ideal * correspondence: sbnava@sci.sjp.ac.lk tel: +94-77-509-5610 issn 2235-9370 print/issn 2235-9362 online © university of sri jayewardenepura navaratne /journal of tropical forestry and environment vol. 5. no 02 (2015) 60-66 61 solution to control the sugar fermentation process (ratnasooria et al., 2006), that negatively perceived by the consumers in the dynamic market. since sugar fermentation process is carried out by the yeast, it is capable to produce different kind of enzymes to convert carbohydrates into sugars and thereafter into alcohol, carbon dioxide and energy (swaminathan, 1988). therefore, it can be presumed that water soluble chemical components in hal bark may be able to either kill the microorganisms or convert them dormant or defunct or destroying the enzymes they produced during the process of sugar fermentation. therefore, a study was conducted to evaluate the scientific background of the hal bark against the sugar fermentation process as well to find out an appropriate drying method to preserve antiseptic chemical components of it. 2. methodology 2.1 determination of the best drying method in drying of hal bark 2 kg of fresh hal bark were taken and cut into small pieces (2×2 cm) using a stainless steel knife. thereafter, these pieces were divided into four equal portions and each portion was dried in the sun for 72 hrs, under shade for 12 hrs, in a mechanical dryer (sensible heating at constant humidity ratio at 75-80° c) for 36 hrs and in a cooling with a dehumidifying dryer at 6-8° c for 96 hrs until moisture content reached to 6-8%. thereafter, 1.5 g of dried hal bark from each treatment was introduced into 100 ml of 40% sugar (sucrose) solution along with 1.0 g of compressed yeast. finally, efficacy of each drying process was monitored in terms of volume of froth formation within 20 minutes time. three replicates were used for all treatments. 2.2 determination of desirable amount of hal bark that can be incorporated into a sugar solution dried hal bark obtained from the best drying process was subjected for this study. therein, 0.5, 1.0, 1.5, 2.0 and 3.0 g of dried hal bark were introduced into 100 ml of 50% sucrose solutions with the view to determine up to which level that the hal bark can be incorporated into a sugar solution without disturbing to its sugar taste (sweet taste). thereafter, 10 numbers of trained sensory panellists were asked to taste the sensory stimulus sweetness of each sugar solution and to indicate the level that hal bark can disturb the sugar taste sensoraly. three replicates were used for all treatments. 2.3 determination of desirable sugar concentration that hal bark can prevent sugar-yeast fermentation four sugar solutions at 30%, 40%, 50% and 60% concentrations were taken and introduced into 100 ml measuring cylinders up to 80 ml and then 1.5 g of dried hal bark from the best drying process along with 0.8 g of compressed yeast was introduced. all treatments were kept at the same environmental condition (30° c, rh 70%) for 30 minutes. thereafter, these four treatments were allowed for fermenting and height of the froth formed was measured. all treatments were replicated thrice and mean value of the height of the froth formed were used to plot a graph sugar concentration verses height of the froth. the same procedure was adapted to same sugar concentrations without incorporation of hal bark as a control treatment. 2.4 determination reducing, non-reducing and total sugars of a hal bark treated sugar solution best amount of hal bark (1.0 g for 100 ml of sugar solutions) that did not disturb the sugar taste sensoraly was taken from the best drying process and introduced into 50% sugar solution along with 1.0 g of compressed yeast. thereafter, the treatment was allowed for fermentation for 30 minutes and fermented solution was used in determining of total sugar, reducing sugar, and non reducing sugar. the trial was replicated thrice and mean value of them were taken to interpret the results. same procedure 62 was adapted to 50% sugar solution without incorporation of 1.0 g hal bark as a control treatment while replicating all treatments thrice. 2.5 determination of total sugar 5 g of sugar was measured into a conical flask and distilled water was added up to 250 ml in order to prepare a standard sugar solution. 25 ml from the prepared` solution was taken into a beaker and 15 ml of 1n concentrated hydrochloric acid and about 10 ml distilled water were added. the flask was kept at 70° c for 10 min in a water bath, cooled immediately and neutralized with 10% naoh along with 2-3 drops of phenolphthalein indicator. the neutralised invert solution was transferred quantitatively into a graduated flask and made up the volume to 200 ml. portion of the solution was poured into a 50 ml burette. 10 ml of fehling’s a and b mixed solution with few drops of methylene blue was put into a 300 ml of conical flask and titrated against the burette solution while boiling until solution reach brick red. (1) where: v2 = titrated volume, ml w = weight of sugar, g 2.6 determination of reducing sugar standard sugar solution (5 g of sugar dissolved in 250 ml of distilled water) was put into a 50 ml burette. 10 ml of fehling’s a and b mixed (5 ml each) solution was put into a 300 ml conical flask and gently boiled the contents in the flask for two minutes. at the end of 2 min of boiling, 1 ml of methylene blue indicator was added into the solution without interrupting boiling. while content of the flask continued to boil, started adding the prepared solution from the burette till the blue colour of the indicator just disappears. (2) where: v1 = titrated volume, ml determination of non-reducing sugar non-reducing sugar was calculated by subtracting the amount of reducing sugar from the amount of total sugar. 3. results 3.1 determination of the best drying method in drying of hal bark table 1: method of drying vs. volume of froth formation in sugar solutions. method of drying volume of froth in 3 replicates (ml) 1 2 3 mean volume sun drying shade drying mechanical drying cooling with dehumidified drying 1.0 0.2 2.0 0.0 1.2 0.0 1.8 0.0 0.8 0.1 2.0 0.0 1.0 0.1 1.9 0.0 navaratne /journal of tropical forestry and environment vol. 5. no 02 (2015) 60-66 63 3.2 determination of desirable amount of hal bark that can be incorporated into sugar solutions the actual threshold level of hal bark (the quantity of hal bark needed to detect hal taste in sugar solutions) in a 50% sugar solution was determined by using 10 members trained sensory panel according to the method described by stone and sidel (1985). results are given in the table 2. table 2: actual thresh hold level of hal bark in a 50% sugar solution. amount of hal bark (g) test result 0.5 1.0 1.5 2.0 3.0 not noticeable not noticeable slightly noticeable noticeable noticeable and disturbing to the sugar taste 3.3 determination of desirable sugar concentration that hal bark can prevent sugar-yeast fermentation the height of the froth formation of sugar solutions at 20%, 30%, 40%, 50%, and 60% concentrations with and without hal bark were measured and results are depicting in the figure 1. figure 1: sugar concentration versus height of the froth 3.4 determination of reducing, non-reducing and total sugars of hal a bark treated sugar solution occurring in reducing sugar, non reducing sugar and total sugar were analysed in 50% sugar solutions, treated with and without hal bark. results are given in (table 3). 0 5 10 15 20 25 20 30 40 50 60 f r o th h t, m m sugar content% ht without bark ht with bark 64 table 3: changes occurring in reducing sugar, non reducing sugar and total sugar of sugar solutions treated with and without hal bark. fermentation time (min) without hal bark with hal bark reducing sugar % non-reducing sugar % total sugar % reducing sugar % non reducing sugar % total sugar % 00 10 20 30 40 50 0.5 1.5 4.5 11.0 16.6 21.4 46.5 44.0 37.7 29.8 20.8 13.1 47.0 45.5 42.2 40.8 37.4 34.5 0.5 0.7 0.8 1.1 1.2 1.2 46.5 46.2 46.0 45.8 45.5 45.5 47.0 46.9 46.8 46.9 46.7 46.7 4. discussion cooling with dehumidified drying process is capable to suppress sugar fermentation process remarkably in compared to the other treatments, especially with fresh and oven dried hal bark. as fresh hal bark contains more water (about 30-35%) rather than having more antiseptic chemical components, its effectiveness in controlling of sugar fermentation process is less. in the case of oven dried hal bark, effectiveness is relatively less because, high temperature available in the drying air may cause for destroying or vaporisation of the chemical components important for antiseptic properties in prevention of sugar–yeast fermentation process (champion college of agriculture, 1984). therefore, cooling with dehumidified drying process is the best drying method in order to preserve antiseptic properties of the hal bark because low temperature (6-8° c) and low water vapour pressure of the cold air are capable to dry the hal bark properly without disturbing to its antiseptic chemical components. however, sun drying and shade drying are also productive options in drying of hal bark, because relatively low drying temperature of these drying processors are also capable to preserve antiseptic properties of the hal bark. same view has been expressed by rahman (1980). even though the hal bark is an appropriate source for controlling of sugar-yeast fermentation process, bitterness of the bark is severely affecting the sensory stimulus “the sugar taste “of the sugar solution. thus detection of the sensoraly acceptable level of hal bark to be incorporated into sugar solutions as well as that level is to be capable to control yeast fermentation process are important. hence, 1 g of dried hal bark for a 100 ml of sugar solution is the ideal amount in prevention of yeastsugar fermentation process as well as not disturbing to the sugar taste of the sugar solution. hal bark is capable to control “sugar-yeast fermentation process” completely when sugar concentration remained 50% or above with 1% hal bark. however, same performance was shown by the control treatment at 60% sugar concentration due to high osmosis pressure of the sugar solution itself. therefore, ability of hal bark in controlling of sugar fermentation process is depending on a range between 50% to 60%, because naturally 60% or above sugar concentrations are capable to control yeast-sugar fermentation process completely due to high osmosis pressure of the sugar concentration (stanley and linda, 1988). hence, hal bark can be used as a preventive treatment in controlling of the growth of yeast in high concentrated sugar solutions rather than controlling of sugar yeast fermentation process in low sugar solutions including trickles too. navaratne /journal of tropical forestry and environment vol. 5. no 02 (2015) 60-66 65 the treatment used as “without hal bark” clearly indicated that total sugar content is steadily declining over the time, because living yeast cells utilise the sugar in order to carry out their metabolic activities. c6h12o5 co2 + ch3ch2oh + energy (3) declining of the sugar content is caused by the production of alcohol and liberation of co2 as a by product during the sugar-yeast fermentation process (norman and james, 1977). in the case of declining of non-reducing sugar and increment of reducing sugar are caused by the breakdown of the sucrose into glucose and fructose units by the invertase enzyme secrets by the yeast cells (cason et al., 1987) as given below. sucrose invertase enzyme glucose + fructose (4) just after detachment of the glucose and fructose units from the sucrose, these simple sugar units remained in ring form. as long as these individual glucose and fructose units remained in ring form, which is called as non reducing state of the sugar. however, soon after liberation of these individual glucose and fructose units (in ring structure), hydrolysed into straight form which is called reducing state of the sugar. when simple sugars are converted into reducing state, the yeast cells are capable to use these sugars for their metabolic activities. the treatment incorporated with hal bark, contained two important chemicals, namely copalliferol a and b, which are capable to prohibit growth of yeast in the sugar solution. hence, hal bark incorporated sugar solution did not show increment or decrement of total sugar, non-reducing sugar and reducing sugar significantly comparatively controlled treatment. 5. conclusion cooling with dehumidified drying method is the most effective drying method to preserve anti microbial properties of hal bark. the desirable amount of hal bark and sugar concentration in controlling of sugar yeast fermentation process are 1.0g and 50% respectively. using more than 1.0 g of hal bark into sugar solutions disturbs the sugar taste because of somewhat bitter taste of hal bark. hal bark is capable to maintain reducing sugar, non-reducing sugar and total sugar in 50% or more concentrated sugar solutions. finally, hal bark can be used in controlling of fermentation process of concentrated sugar solutions, including trickle too. references cason, d.t., reid, g.c. and gatner, e.m.s. 1987. on the differing rates of fructose and glucose utilisation in saccha-romyces eerevisiae. journal of industrial brewery, 93: 23-25. cauvain, s.p. and young, l.s. 1988. technology of bread making. campden and chorleywood food research association, gloucestershire, uk. published by blackie academic and professional, london, uk. champion college of agriculture.1984. (coperative extension service circular 1127), in drying food. dassanayake, m.d. and fosberg, f.r. 1980. a revised hand book to the flora of sri lanka. smithsonian institution and the national science foundation, american publishing co. pvt. ltd. 581.9(548.7). desrosier, n.w. and desrosier, j.n. 1977. the technology of food preservation (4 th edition). cbs publishers and distributers, delhi, india. 66 kostermans, a.j.g.h. 1982. a hand book of the dipterocarpaceae of sri lanka. wildlife heritage trust of sri lanka. rahman, n.s. 1980. hand book of food preservation. (2 nd edition): crc press, taylor and francis group. ratnasooriya, w.d., lelwala, l.h.d.s., kannangara, k.n.k. and sandanayake, s.d.d. 2006. sedative activity of steam bark of sri lankan endemic plant, fitoterapia, 77: 331-332 stone, h. and sidel, j.l. 1985. sensory evaluation practices. academic press, orlando, usa. swaminathan, m. 1988. hand book of food science and experimental foods. (1 st edition). the bangalore printing and publishing co. ltd., bangalore, india. chapter five: discussion krishnanantham et al. /journal of tropical forestry and environment vol. 5. no 01 (2015) 59-70 59 a preliminary study on vegetation structure and mangrove diversity in irakkandy lagoon, trincomalee k. krishnanantham 1 , y.b.m.c.j. seneviratne 2 and s.c. jayamanne 1* 1 uva wellassa university, badulla, sri lanka 2 gef/ifad-pczrsm project office, department of coast conservation and coastal resource management, trincomalee, sri lanka date received: 22-11-2014 date accepted: 29-04-2015 abstract the present study was carried out during the period from may to july 2014 to assess the vegetation pattern and to estimate biomass of the mangroves in irakkandy lagoon, trincomalee. five belt-transects of 10 m in width were laid perpendicular to the shoreline. data were collected on tree diameter at breast height (dbh) and tree height from each sub-plot (100 m 2 ) in belt transects using standard methods. above ground biomass, basal area and relative density of the mangroves were also estimated. diversity and evenness of each sub-plot was calculated using shannon-wiener diversity index and pielou’s evenness index respectively. results revealed that the study site is composed of 5 true mangrove species and highest density was recorded for avicennia marina (414 trees/ha, 700 saplings/ha, 2354 seedlings/ha), followed by lumnitzera racemosa, excoecaria agallocha, rhizophora apiculata and heritiera littoralis. the greatest mangrove diversity (1.28) was observed in subplot 1 of transect 2. the least mangrove diversity (0) was found in transect 5. there is a significant difference among transects concerning the diversity and evenness (p<0.05). the results showed that avicennia marina was the dominant species with height (h) and dbh of 3.65±1.43 m and 5.06±1.07 cm respectively, followed by lumnitzera racemosa (3.36±1.19 m and 5.81±1.06 cm, excoecaria agallocha (4.92±2.45 m and 5.31±1.93 cm), rhizophora apiculata (4.56±1.70 m and 4.89±0.96 cm) and heritiera littoralis (8.80±0.849 m and 26.50±4.95 cm). the above ground biomass of lumnitzera racemosa was recorded as 8334.89 kg/ha and avicennia marina was recorded as 1361.13 kg/ha. species diversity (h’) of whole mangrove area studied was 0.86 and evenness (e) was 0.54. it reveals that irakkandy lagoon consists of fairly high biological diversity (diversity index=0.86) of mangroves and extremely valuable for stability of the ecosystem. keywords: mangroves, biomass, diversity, irakkandy 1. introduction mangroves are woody plants, which grow in loose wet soils of brackish-to-saline estuaries and shorelines in the tropics and sub-tropics (joshi and ghose, 2003). approximately 25% of the world’s tropical coastline is comprised of mangrove ecosystems. they are estimated to be an area between 167,000 km 2 and 181,000 km 2 , in 112 countries (spalding et al., 1997; kathiresan and bingham, 2001). * correspondence: sepalikauwu@yahoo.com tel: +94 718538975 issn 2235-9370 print/issn 2235-9362 online © university of sri jayewardenepura mailto:sepalikauwu@yahoo.com 60 sri lanka is one of the south asian countries situated in the central of the indian ocean, contains mangrove forests mainly along the northern, north-eastern and eastern coastal lagoons and river estuaries. nearly 23 true mangrove species of trees and shrubs have been recorded in sri lanka (de silva and de silva, 1998). mangroves play a vital role in the ecosystem, by supporting the sustenance of coastal biodiversity (ronnback, 1999), ecotourism (ong and gong, 2013), production of food by photosynthesis (miththapala, 2008), and medicinal value by highest antibacterial activity (abeysinghe, 2010). information available in literature for mangrove ecosystem is scanty for the eastern region of sri lanka. the pressure on mangrove ecosystem increased at an alarming rate during the past two decades due to ethnic conflict and at present due to development activities. in addition, tsunami 2004 has collectively contributed to the destruction of mangroves at large in the eastern province. moreover, people living in association with the mangrove and rely on the mangroves for their sustenance and livelihood would also be affected. irakkandy lagoon is situated in trincomalee district and associated with rich mangrove resources. however, the mangroves of irakkandy have not been studied up to date and there are no published information regarding the mangroves in irakkandy lagoon. information such as vegetation structure, species diversity, density of the stands of mangroves are very important for planning management strategies and conservation of mangroves and the present study was aimed at providing such information required for management of the mangroves in the irakkandy lagoon. 2. methodology 2.1 site selection irakkandy lagoon is located in eastern province of sri lanka; the estimate terrain elevation above sea level is 12 m. it has high mangrove distribution and one of the famous ecosystems in trincomalee district belongs to kuchchaveli ds division. figure 1: map of the irakkandy lagoon. (source: google earthhttp://www.geody.com) n http://www.geody.com)/ krishnanantham et al. /journal of tropical forestry and environment vol. 5. no 01 (2015) 59-70 61 one of the branches of this lagoon begins from 8 th mile post while other branch starts from kumburupity south sinna karachi and both joins the sea near irakkandy river mouth. the lagoon includes four gn divisions named vaalaiuttru, irakakandy, kumburupity east and kumburupity south. 2.2 vegetation structure data were collected from may to july 2014 at the selected samples. five sampling sites were chosen randomly to carry out the study (figure 2). georeferencing was done by the portable gps unit (garmin ® etrex 10). five belt-transects of 10 m in width were laid perpendicular to the shoreline in each sites. each transect was sub-divided into 10×10 m with three sub-plots (100 m 2 ) and data on mangrove vegetation structure, i.e., species, tree diameter at breast height (dbh), tree height (h), density and basal area were obtained from each sub-plot (100 m 2 ). above ground biomass and relative density of the mangroves were also estimated. figure 2: location of transects in irakkandy lagoon. (source: google earth) 2.3 diversity estimation the mangrove species were identified and recorded by using identification keys (ministry of environment and natural resources, 2007). mangrove diversity of each transect was calculated using shannon weiner index (equation 1) (shannon and weaver, 1949). i s 1i i logpph'    (1) where: 'h = shannon diversity index i p = fraction of the entire population made up of species i (proportion of a species i relative to total number of species present, not encountered) s = numbers of species encountered high value of h' would be a representative of a diverse and equally distributed community and lower values represent less diverse community. a value of 0 would represent a community with just one species. the evenness of the species was calculated by the pielou’s evenness index (pielou, 1966) using in equation 2. transect 1 transect 2 transect 3 transect 4 transect 5 62 /lnsh'e  (2) where: 'h =shannon diversity index s = total number of species in the sample e = pielou’s evenness index the above-ground biomass (agb) of the mangrove stands was estimated using the allometric relationship between above-ground biomass, diameter at breast height (dbh) and height (cintron and schaeffer-novelli, 1984; komiyama et al., 1988; tam et al., 1995; komiyama et al., 2000). equations 3 to 8 illustrate the methods used to estimate them. avicennia marina    0.529 2 hdbh123.59agb  (3) rhizophora apiculata    0.529 2 hdbh23.64agb  (4) lumnitzera racemosa   2.5 dbh102.30agb  (5) p stand basal area and relative density were calculated following equations (english et al., 1994). basal area   4 cmπdbh ba 22  (6) stand basal area plot the of area ba ba stand   m 2 ha -2 (7) relative density rd = (no. of individuals of a species/total no. of individuals in all species) ×100 (8) 2.4 statistical analysis general linear model (anova) and correlation were employed to analyse the data using minitab 16 software. 3. results 3.1 identification of true mangrove plants and mangrove associated plants table 1 indicates identified true mangrove species during study period in irakkandy lagoon. krishnanantham et al. /journal of tropical forestry and environment vol. 5. no 01 (2015) 59-70 63 table 1: identified mangrove plants in irakkandy lagoon. five true mangrove species belonging to five different families were identified from the irakkandy lagoon. avicennia marina (avicenniaceae) was the dominant species while heritiera littoralis (sterculiaceae) was rare. figure 3 shows the morphological characteristics of the species in the table 1. 3a: avicennia marina 3b: lumnitzera racemosa 3c: excoecaria agallocha family species name local name avicenniaceae avicennia marina (forssk.)vierh manda (sn), venkandal (tn) combretaceae lumnitzera racemosa willd beriya (sn), tipparuthin (tn) euphorbiaceae excoecaria agallocha l. telakiriya (sn), tilai (tn) rhizophoraceae rhizophora apiculata blume. kadol (sn), kandal (tn) sterculiaceae heritiera littoralis dryand. etuna (sn), choomuntiri (tn) 64 3d: rhizophora apiculata 3e: heritiera littoralis figure 3: morphological characteristics of true mangroves found in irakkandy lagoon. 3.2 mangrove associated plants nine mangrove associated plants (table 2) were identified in irakkandy lagoon during the study period. figure 4 illustrates their morphological characteristics. table 2: identified mangrove associated plants in irakkandy lagoon. family mangrove associate plants local name verbenaceae premna integrifolia l. mahamidi (sn), munnai (tn) verbenaceae clerodendrum inerme garetn. walgurentha (sn), pichuvilaaththi (tn) arecaceae phoenix pusilla l. wal inthi (sn), eechchai (tn) fabaceae caesalpinia bonduc l. kumburuwel (sn), kalachchi (tn) sapotaceae mimusops elengi l. munamal (sn), mahil (tn) salvadoraceae salvadora persica l. perungoli, karkol (tn) malvaceae thespesia populnea l. gansooriya (sn), poovarasu (tn) pandanacea pandanus tectorius parkinson ex zucc. vaetakeiyya (sn), thaalai (tn) vitaceae cissus quadrangularis l. pirandai (tn) krishnanantham et al. /journal of tropical forestry and environment vol. 5. no 01 (2015) 59-70 65 4a: premna integrifolia 4b: caesalpinia bonduc 4c: cissus quadrangularis 4d: clerodendrum inerme 4e: thespesia populnea 4f: pandanus tectorius 4g: phoenix pusilla 4h: salvadora persica 4i: mimusops elengi figure 4: morphological characteristics of the mangrove associates found in the irakkandy lagoon. 66 0 1 2 3 4 5 s .p .1 s .p .2 s .p .3 s .p .4 s .p .5 s .p .6 s .p .7 s .p .8 s .p .9 s .p .1 0 s .p .1 1 s .p .1 2 s .p .1 3 s .p .1 4 s .p .1 5 n u m b e r o f sp e c ie s sub-plots hl ea lr ra am 3.3 species richness species richness of the fifteen sub-plots is given in figure 3. as indicated by figure 3, species richness was high in sub-plot 3 and sub-plot 4. figure 3: species richness in each plots. (transect 1: sp1sp3, transect 2: sp4sp6, transect 3: sp7sp9, transect 4: sp10sp12, transect 5: sp13sp15, am=avicennia marina, ra=rhizophora apiculata, lr=lumnitzera racemosa, ea= excoecaria agallocha, hl=heritiera littoralis). 3.4 floristic composition of mangroves in irakkandy lagoon floristic composition of mangroves in five transects in irakkandy lagoon are depicted in table 3. percentage of individual species encountered in each belt transect are given. table 3: floristic composition of mangroves in five belt transects in irakkandy lagoon. percentage of mangrove species in each transects (t) true mangrove species 1 2 3 4 5 avicennia marina 22.12 4.62 49.04 17.49 6.73 rhizophora apiculata 0.00 23.92 38.04 38.04 0.00 lumnitzera racemosa 20.00 30.00 35.00 15.00 0.00 excoecaria agallocha 13.46 30.77 15.39 23.08 17.30 heritiera littoralis 100.00 0.00 0.00 0.00 0.00 avicennia marina (avicenniaceae) dominated all belt transects. rhizophora apiculata (rhizophoraceae) was not observed in t1 and t5 while lumnitzera racemosa (combretaceae) was not observed in t5 compared to other transects. excoecaria agallocha (euphorbiaceae) was found in all transects, while heritiera littoralis (euphorbiaceae) was observed only in t1. table 4 depicts the shannnon diversity index and pielou's index observed in each transects. high value of shannon-wiener index (1.352) was observed in transect 2 while the least mangrove diversity was found in transect 5. t2 has high species evenness (0.975) while t1 has low species evenness (0.367). the maximum evenness index value observed was (0.975) while highest shannonwiener index value was 1.352. hence the highest diversity was observed in transect 2. krishnanantham et al. /journal of tropical forestry and environment vol. 5. no 01 (2015) 59-70 67 table 4: shannnon diversity index and pielou's index by transects. true mangrove species transects (t) 1 2 3 4 5 shannon-wiener index 0.509 1.352 0.644 0.973 0.507 pielou’s evenness index 0.367 0.975 0.464 0.702 0.731 3.6 existence number of mangrove trees, sapling and seedlings table 5: the existent number of mangrove trees, saplings and seedlings. (tree=d>4 cm; sapling=d<4 cm, h>1 m; seedling=h<1 m) avicennia marina was the most abundant tree with 414 trees/ha followed by lumnitzera racemosa (160 teees/ha), excoecaria agallocha (140 trees/ha), rhizophora apiculata (100 trees/ha) and heritiera littoralis (14 trees/ha). moreover, avicennia marina sapling showed the highest dispersal followed by rhizophora apiculata, excoecaria agallocha and lumnitzera racemosa. when considering the seedlings, avicennia marina was the highest dispersal (2354 seedlings/ha) followed by rhizophora apiculata, excoecaria agallocha and lumnitzera racemosa. table 6 depicts the mean height, dbh, relative density and basal area of mangrove stand. table 6: height, dbh, relative density and basal area of species. mangrove species mean height (m) mean dbh (cm) relative density (%) basal area (m 2 /ha) avicennia marina 3.65 ± 1.42 5.06 ± 1.07 73.65 0.87 lumnitzera racemosa 3.36 ± 1.19 5.82 ± 1.06 5.67 0.44 excoecaria agallocha 4.93 ± 2.44 5.31 ± 1.93 7.37 0.35 rhizophora apiculata 4.56 ± 1.70 4.89 ± 0.97 13.03 0.20 heritiera littoralis 8.80 ± 0.85 26.50 ± 4.95 0.28 0.75 the highest tree height (8.8 m) and dbh (26.5 cm) were observed belongs to heritiera littoralis which could be found far from the shore. the lowest total basal area was recorded by rhizophora apiculata as 0.20 m 2 /ha. some of the mangrove species like h. littoralis, e. agallocha, and l. racemosa were observed far from the shore. a. marina and r. apiculata presence could be found in the edge of the shore line often. table 7 shows the above-ground biomass for the mangrove species. table 7: above-ground biomass of mangrove species. mangrove species above ground biomass (kg/ha) avicennia marina (avicenniaceae) 1361.1 lumnitzera racemosa (combretaceae) 8334.9 rhizophora apiculata (rhizophoraceae) 377.2 mangrove species trees/ha saplings/ha seedlings/ha avicennia marina 414 700 2354 lumnitzera racemosa 160 94 14 excoecaria agallocha 140 174 34 rhizophora apiculata 100 334 180 heritiera littoralis 14 0 0 68 above-ground biomass of a. marina has been found out as 1362.1 kg/ha while above-ground biomass of r. apiculata was found out as 377.2 kg/ha. there is a significant difference among transects concerning the diversity and evenness (p<0.05). there is a positive moderate linear relationship between mangrove species and distance from the shore (p<0.05) and no significant difference found between mangrove species and tree height (p>0.05). 4. discussion diversity is the total range of plant species features in an area (kamaruzaman et al., 2007). the calculation of shannon-wiener index simply expresses the number of different species in a particular area. a high value of shannon-wiener index (1.352) would be a representative of a diverse and equally distributed community in transect 2 and lowest value (0.507) represent less diverse community in transect 5. species evenness is a measure of biodiversity which quantifies how equal the populations are numerically (kamaruzaman et al., 2007). pielou’s evenness index which is the relative abundance with each mangrove species is represented in an area. transect 2 where all the mangrove species are represented by the same number of individuals has high species evenness (0.975). transect 1 where some species are represented by many individuals and other species are represented by very few individuals has low species evenness (0.367). pinto (1982) has indicated that presence of a rhizophora border on the shore may be due to its morphological adaptations in resisting water currents with the help of prop roots. presence of a rhizophora border occurs may be due to the depth and slope as well as due to the lack of sandy soil and poor aeration. some of the mangrove species like h. littoralis, e. agallocha, l. racemosa were observed far from the shore. de silva and de silva, (1998) has explained that in sri lanka, h. littoralis grows away from the tidal influence. there is a positive moderate linear relationship between mangrove species and distance from the shore (p<0.05). saha and choudhury (1995) have reported that mangrove forest experiencing total diurnal inundation is dominated by a. marina while e. agallocha dominate sites that are not completely inundated. it can be clearly shown in irakkandy lagoon. amarasinghe et al. (2013) has found that a. marina do not grow in fresh water and may be obligate halophytes. also they explained that e. agallocha survives well in fresh water and may not have obligatory requirement for salt beyond trace amount. mangrove vegetation structural data at kadolkele in negombo estuary shows that higher numbers of species, densities, and heights occur at the areas close to the shoreline that get inundated with estuarine waters most frequently than in the landward areas that are dominated by a. marina (jayakody et al., 2008). the abundance of saplings and seedlings gives an indication of the natural regeneration occurring (kamaruzaman et al., 2007). the highest total of saplings and seedlings were recorded for a. marinawas 700 ha -1 and 2,354 ha -1 respectively. from this data, total number of seedling per hectare showed a good regeneration potential. h. littoralis only occur in one plot shows low of distribution (kamaruzaman et al., 2007). 5. conclusion a total of five mangrove species from different families were identified in irakkandy lagoon. avicennia marinawas dominated this study area with 414 trees/ha recorded while, heritiera littoralis showed very low number with only 14 trees/ha recorded. this forest type has a potential regeneration since high total numbers of seedling per hectare (2,582) were observed. total tree basal area for this krishnanantham et al. /journal of tropical forestry and environment vol. 5. no 01 (2015) 59-70 69 study area is 2.597 m 2 /ha. the greatest mangrove diversity (1.352) in terms of species richness is highest in transect 2 and the lowest mangrove diversity (0.507) was belongs to transect 5. species diversity (h’) of whole mangrove area studied was 0.86 and evenness (e) was 0.54. the results of the study indicate irakkandy lagoon consists of low biological diversity of mangroves compared to negombo, chilaw and puttalam lagoons but is extremely valuable as a living mangrove forest due to its extent. acknowledgement the authors acknowledge the department of coast conservation and coastal resources management for the field activities. references abeysinghe, p.d. 2010. antibacterial activity of some medicinal mangroves against antibiotic resistant pathogenic bacteria. indian journal of pharmaceutical sciences. 72(2): 167-172. amarasinghe, m.d., de silva, k., jayakody, j. and pahalawattaarachchi, v. 2008. vegetation structure and potential gross primary productivity of mangroves at kadolkele in meegamuwa (negombo) estuary, sri lanka. sri lanka journal of aquatic sciences. 13: 95-108. amarasinghe, m.d. 2013. vegetation structure and species distribution of mangroves along a soil salinity gradient in a micro tidal estuary on the north-western coast of sri lanka. m. phil. thesis. university of kelaniya, sri lanka. baker,v., english,s. and wilkinson,c. 1994. survey manual for tropical marine resources. australian institute of marine science, townsville, pp 368. bingham b.l. and kathiresan, k. 2001. biology of mangroves and mangrove ecosystems. journal of advances in marine biology. 40: 81-251. biodiversity secretariat, ministry of environment and natural resources, 2007. a field guide to the mangroves of sri lanka. protected area management and wildlife conservation project. blasco. f., field c.d. and spalding, m.d. 1997. world mangrove atlas. okinawa (japan): international society for mangrove ecosystems. bowen, j., valiela, i. and york, j. 2001. mangrove forests: one of the world's threatened major tropical environments. bioscience. 51(10): 807-815. chen, g.z., lan, c.y.,tam, n.f.y. and wong, y.s. 1995, community structure and standing biomass of a mangrove forest in futian nature reserve, shenzhen, china. hydrobiologia. 295: 193-201. choudhury. a. and saha, s. 1995. vegetation analysis of restored and natural mangrove forests in sagar island, sundarbans, east coast of india. indian journal of marine sciences. 24: 133-136. cintron, g., schaeffer-novelli, y. 1984. methods for studying mangrove structure, in: snedaker, j.g., snedaker, s.c. (eds.), the mangrove ecosystem: research methods. unesco, bungay, united kingdom, pp. 91-113. de silva, m. and de silva, p.k.1998. status, diversity and conservation of the mangrove forests of sri lanka. journal of south asian natural history. 3(1): 79-102. district project office, department of coast conservation and coastal resource management. trincomalee. 2013 sri lanka. primary data collection: trincomalee district. fujimoto, k., havanond, s., ishihara, s., komiyama, a., miyagi, t., mochida, y., ohnishi, t., srisawat, w. 2000. top/root biomass ratio of a secondary mangrove (ceriops tagal (perr.) c.b. rob.) forest ecology and management.139: 127-134. ghose, m. and joshi, h. 2003. forest structure and species distribution along soil salinity and ph gradient in mangrove swamps of the sundarbans. tropical ecology. 44(2): 195-204. ghose, m. and joshi, h. 2003. journal of tropical ecology. 44: 197-206. 70 gomes soares, m.l. and schaeffer-novelli, y. 2005. above-ground biomass of mangrove species. i. analysis of models. estuarine, coastal and shelf science. 65(1-2): 1-18. gong, w.k. and ong, j.e. 2013. structure, function and management of mangrove ecosystems. isme mangrove educational book series no. 2. international society for mangrove ecosystems (isme), okinawa, japan, and international tropical timber organization (itto), yokohama, japan. heip, c. 1974. a new index measuring evenness. journal of the marine biological association. 54(3): 555. jayakody, j.m.a.l., amarasinghe, m.d., pahalawattaarachchi, v. and de silva, k.a.w.l. (2008). vegetation structure and potential gross primary productivity of mangroves in kadolkelein meegamuwa (negombo) estuary, sri lanka. sri lanka j. aquat. sci. 13: 95-108. kamaruzaman, j., kasawani, i. and nurun-nadhirah, m. i. 2007. biological diversity assessment of tok bali mangrove forest, kelantan, malaysia, wseas transactions on environment and development, 2(3). kato, s., komiyama, a. and poungparn, s. 2005. common allometric equations for estimating the tree weight of mangroves. journal of tropical ecology. 21(4): 471-477. komiyama, a., havanond, s., srisawatt,w.,mochida, y., fujimoto, k., ohnishi, t., ishihara, s. and miyagi, t. 2000. top/root biomass ratio of a secondary mangrove (ceriops tagal (perr.) c. b. rob.) forest. forest ecol. manage. 139: 127–134. komiyama, a., moriya, h., ogino, k., prawiroatmodjo, s. and toma, t. 1988. primary productivity of mangrove forest, in: chihara, m. and ogino, k. (eds.), biological system of mangroves. ehime university, matsuyama, pp. 97–117. miththapala, s. 2008. mangroves. 1st ed. colombo, sri lanka: ecosystems and livelihoods group asia, iucn. peter j.f. and spellerberg, i.f. 2003. a tribute to claude shannon (1916-2001) and a pleafor more rigorous use of species richness, species diversity and the shannon-wiener index. journal of global ecology and biogeography. 12(3): 177-179. pinto, m.l. 1982. distribution and zonation of mangroves in the nothern part of thenegombo lagoon (sri lanka). journal of the national science council of sri lanka. 10(2): 245-255. ronnback, p. 1999. the ecological basis for economic value of seafood production supported by mangrove ecosystems. journal of international society for ecological economics. 29(2): 235 252. saha, s. and choudhury, 1995. vegetation analysis of restored and natural mangrove forests in sagar island, sundarabarns, east coast of india, indian journal of marine sciences, 24, 133-136. shannon, c.e. and weaver, w. 1949. the mathematical theory of communication. the university of illinois press, urbana, 117pp. spalding, m., f. blasco and c. field, 1997. world mangrove atlas. the international society for mangrove ecosystems, okinawa, japan . 178 pp. tam, n.f.y., wong, s.y., lan, c.y., and chen, g.z. 1995. community structure and standing biomass of a mangrove forest in futian nature reserve, shanzhen, china. hydrobiologia. 295: 193-201. karyati et al. karyati, ipor, jusoh & wasli /journal of tropical forestry and environment vol. 4, no 01 (2014) 28-39 28 soil properties under various stages of secondary forests at sarawak, east malaysia k. karyati 1* , i.b. ipor 2 , i. jusoh 2 and m.e. wasli 2 1 faculty of forestry, university of mulawarman, samarinda, east kalimantan, indonesia 2 faculty of resource science and technology, universiti malaysia sarawak, kota samarahan, sarawak, malaysia date received: 07-11-2013 date accepted: 26-01-2014 abstract changes in the forest community during secondary succession are influencing in various soil properties. however, there is limited information available on the soil properties under different stages of secondary forests in sarawak. the aims of this study are to clarify the soil morphological and physicochemical properties at secondary forests under different age stands after similar land change (slash and burn). field surveys were conducted at 3, 5, 10, and 20 years old of secondary forests in sabal, sarawak. different fallow time influence changing soil properties in various stage secondary forests. a number of soil properties affected soil development process and land use change. soil morphological and physicochemical properties differed under different stages of fallow periods. the results showed that the soils under different stages of fallow lands after shifting cultivation in the study sites was categorized in acidic soil as indicated by ph (h2o) values of below than 5 and the low content of t-c and t-n as well as exchangeable bases. the close relationship can be assumed between soil development process and vegetation succession. the knowledge of forest soil properties is essential to understand the change and development process under various stages secondary forests. the comprehensive understanding about soil properties and development process is important in order to conserve and manage secondary forests. keywords: secondary forest, fallow age, shifting cultivation, soil morphological properties, soil physicochemical properties ___________________________________________________________________________ 1. introduction shifting cultivation has been practiced all over the world and two-thirds of the world’s secondary forest in 1980 was shifting cultivation fallow (lanly, 1982). historically, shifting cultivation has created much impact on the general landscape of rural malaysia particularly in sabah and sarawak over the last 100 years (latiff & zakri, 1998). in addition, about 49% of the area deforested annually in tropical asia is attributed to shifting cultivation (lanly, 1982). shifting cultivation is accounted for some 28% of land use and it has been suggested that some 3.2 million ha in sarawak are subject to shifting cultivation (jomo et al., 2004). * correspondence: karyati.hanapi@yahoo.com tel:+62 541749068 issn 2235-9370 print/issn 2235-9362 online © university of sri jayewardenepura mailto:karyati.hanapi@yahoo.com 29 secondary forest is the type of vegetation that results after the natural high forest vegetation has been disturbed or cleared for shifting cultivation prior to abandonment (misra, 1992; abebrese, 2002; johnson & miyanishi, 2007; keddy, 2007). after field abandonment, the secondary forest develops naturally (van do et al., 2010). the secondary forests are reflected in their structure and extent of vegetative cover, as well as their composition in terms of dominant and secondary species (mittelman, 2001). forest succession alters the chemical, physical, and biological properties of the soil through their occupancy of the area, and it is likely that these alterations contribute to the relative changes in the abundance of the dominant plant species that characterises successional aspect on the land (fisher & binkley, 2000). rapid changes in the secondary successional fallow environment is reflected by the declining in light availability for the growth of the shoot system as well as the changes in the nutrient distribution within the soil horizon during the early to late successional fallow environment (ramakrishnan & kushwaha, 2001). a number of soil properties can be used to infer a great deal about how a particular soil influences plant growth and its well-being (harris, 1992; fisher & binkley, 2000). it is the ability of the soil to supply nutrient elements in the amounts, forms, and proportions required for maximum plant growth. the plant growth depends on the physicochemical properties and organic matter content of the soil (hazra & som, 2006). the soil properties at fallow lands under shifting cultivation could be characterised by strongly acidic nature with low levels of exchangeable bases (nakano & miyauchi, 1996; etsuko et al., 2004; wasli et al., 2009). schedlbauer and kavanagh (2008) noted that mineral soil c storage beneath secondary forests was relatively consistent as secondary forest development progressed. however, feldpausch et al. (2007) reported that the level of c content and all nutrient concentrations in soil had a decreasing trend with increasing soil depth in the secondary forests after abandonment. in addition, lu et al. (2002) reported that soil nutrients such as ca, mg, k, and n decrease with the depth in the soil studied in secondary succession forest. andriesse & schelhaas (1987a) showed a noticeable increase in cation exchange capacity (cec) of the topsoil with burning in their experimental site in sarawak with no dry season. they reported that this rise in cec was closely related to the increase in c because of the incomplete burning of wet organic matter. several studies on soil properties under tropical secondary forests in sarawak, malaysia (andriesse & schelhaas, 1987a, 1987b; tanaka et al., 2007a, 2007b; tanaka et al., 2009; wasli et al., 2009) have been reported. however, still limited studies focused on soil properties at early succession stage of secondary forests after abandonment. in this study, the soil morphological and physicochemical properties in tropical secondary forests, especially at different stages of fallow lands were conducted. 2. materials and methods 2.1 study sites for clarification on the soil properties (morphological and physicochemical properties) under various stage of secondary forests, the assessment was conducted in the secondary forests with the age of 3 years, 5 years, 10 years, and 20 years (hereafter call ed temuda i, temuda ii, belukar i, and belukar ii, respectively) in sabal, sri aman, sarawak, east malaysia (fig. 1) where the previous study on vegetation composition and diversity was conducted by karyati et al. (2013). the original vegetation at sabal site is lowland mixed dipterocarp forest with heath forest (kerangas) (whitmore, 1975; kendawang et al., 2007). the soils of the study site are derived from non-calcareous sedimentary rocks 30 consisting of fine and whitish sandstone during the mid tertiary period (butt, 1983). most of the soils are classified into oxyaquic or spodic quartzipsamments at sabal site based on the usda classification system (soil survey staff, 1994). climate data are collected from sri aman station, which is located nearest to the study sites with consistent climatic records. during the last 20 years (1992-2011), the study sites receive average annual 3,491 mm year -1 of rainfall, 26.6 o c of monthly temperature, and 85.1% of relative humidity. the climate is classified into type a on the schmidt-ferguson classification system (1951). sabal region is characterized as zone a with q (quotient) of 0.013 where very humid area with vegetation of tropical rain forest (karyati et al., 2012). fig. 1: map of the study sites. 2.2 soil profile description for soil profile description, a soil pit with the depth of 1 meter was dug at the centre of each study site, such as temuda i, temuda ii, belukar i, and belukar ii, respectively. soil profile descriptions were conducted adopting the standard procedures by international soil science society (isss) (nrcs, 2002). the soil profile description was conducted by observing the characteristics of the soils moving towards the bottom of profile. some of the characteristics were distinguished such as depth, boundary, colour, field texture, structure, roots, and hardness. soil colour was determined by referring to munsell soil colour chart, while soil texture in the field was determined by “feel” method. soil hardness was measured at every horizon using the yamanaka-type penetrometer. 2.3 soil sampling and physicochemical analyses at each study site, the soils on nine quadrates of 20m×20m were analyzed. soil samples were collected at the depths of 0-10 cm (surface soil) and 20-30 cm (sub-soils) from three random points within the quadrate. the soil samples obtained in triplicate were mixed well to yield one composite sample. the samples were air-dried and then sieved through 2 mm mesh for physicochemical analysis. undisturbed soil samples were also collected using 100 cm 3 core sampler for determination of soil physical properties. soil ph was determined in distilled water and 1 m kcl in a soil to solution ratio of 1:5 by the glass electrode method. electrical conductivity (ec) was measured using a 2 km sabal agroforestry center belukar ii belukar i temuda i temuda ii sungai sabal aping sungai sabal tengah kampung sabal kruin abok kampung abok n simunjan legend : = main road = study site = sabal agroforestry center = village (kampung) malaysi a sarawak brunei darussalam sabah kalimantan barat kalimantan timur kalimantan tengah kalimantan selatan banjarmasin palangkaraya pontianak samarinda kuching k ota kinabalu bandar seri be gawan sabal indonesia n 31 conductivity meter (eutech instruments–cyberscan con 11). the solution was standardized using conductivity meter and was calibrated by standard potassium chloride solution. the content of total carbon (t-c) and nitrogen (t-n) were analyzed using chn analyzer (flashea 1112 series). soil cec was analyzed by distillation (based on ms678 part v: 1980). soil exchangeable cations of calcium, magnesium, potassium, and natrium (exch-ca, exch-mg, exch-k, and exch-na) were analyzed by leaching with neutral ammonium acetate using icp-aes (based on ms678 part iv: 1980). particle size distribution was determined using mechanical analysis and hydrometer. the analysis of soil ph (h2o), ph (kcl), ec, tc, tn, bulk density, and porosity were conducted at laboratory of soil chemistry, faculty of resource science and technology, universiti malaysia sarawak (unimas). the analysis of cec, soil exchangeable cations (exch-ca, exch-mg, exch-k, and exch-na), and particle size distribution were conducted at agriculture research centre (arc) sarawak, malaysia agricultural department. to compare soil properties among four different stages of secondary forests at the depths of 0-10 cm and 20-30 cm, one-way analysis of variance (anova) by tukey’s tests was used. the statistical tests were conducted using spss version 18 for windows (spss inc., 2012). 3. results and discussion 3.1. soil morphological properties under various stages of secondary forests information on the soil morphological properties on a given land can be determined by observing the profile development at various depths of the soil. table 1 presents a summary of soil profile description in the study sites. under similar land use history (slash and burn after shifting cultivation), there were some clear differences among four study sites although soils corresponded to the same soil order, namely ultisols (soil survey staff, 2006). soil profiles of belukar ii showed different content of pa rent materials as compared to the other three sites. soil of temuda i, temuda ii, and belukar i consisted of non-calcareous sedimentary rocks, while the soil of belukar ii was mainly shale and predominantly sedimentary rocks. such properties lead to differ ences in terms of soil classification under sarawak soil classification system for the study sites. the soils of temuda i, temuda ii, and belukar i were classified into grey-white podzolic soils, while red yellow podzolic soils observed in belukar ii (teng, 1993). both soil types consist of parent materials of mainly old alluvium, colluvium or residuum derived fro m arenaceous sedimentary rocks. according to the “feel” texture method the soils at temuda i were classified into sandy loam at horizon o and sandy clay loam at the other horizons (table 1). in this site, the soil structure had moderate very fine sub-angular block to moderate fine sub-angular block with 17 to 19 mm in soil hardness. in horizons of temuda ii, the soil textures were classified into loamy sand, sandy clay, and sandy clay loam. the soil structure was moderate fine subangular block at all horizons, except moderate very fine to fine sub-angular block at horizon ae. the soil hardness was 17 to 21 mm. the result of observation in belukar i, the soil texture were loamy sand at horizons 1a, 1e and 2e2, sandy loam to loamy sand at horizon 2a and loamy sand to sand at horizon 2e1. the observed soil structure were weak very fine subangular blocky at horizons 1a and 1e moderate vey fine sub-angular blocky at horizon 2a and weak to moderate very fine sub-angular blocky at horizons 2e1 and 2e2. the soils of this site had 13 to 22 mm in hardness. in belukar ii, the soils were classified into silty clay loam 32 and silt clay at horizon a and b1, while at horizons b2 and bc were clay based on the “feel” texture method. the soil structures were weak fine sub-angular blocky, moderate fine subangular blocky, strong medium to coarse sub-angular blocky, and massive at horizons a, b1, b2, and bc, respectively. the soil hardness was 12 to 21 mm. table 1: summary of soil profile description in the study sites. horizon depth (cm) boundary a) colour field texture b) structure c) root d) hardness (mm) e) temuda i o <1-0 none a 0-14 gw 2.5y4/2 sl m/sb/vf vfi-fi/co 17 1bh 14-28 cw 2.5y6/4 scl m/sb/vf-f fi/fe;c/vfe 19 e1 28-69 gw 10yr7/3 scl m/sb/f fi/fe 19 2bh 69++ dw 10yr7/6 scl m/sb/f vfi/vfe 19 temuda ii o +2-0 litterfall a 0-16 cw 10yr3/2 ls m/sb/f vfi/co;c/fe 17 ae 16-38 gw 10yr6/3 sc-ls m/sb/vf-f vfi/vfe 20 e1 38-69 gw 10yr8/4 sc m/sb/f vfi/vfe 21 e2 69++ dw 10yr8/3 scl/sc m/sb/f n 20 belukar i o +5-0 litterfall with rootmat layers 1a 0-7 cw 10yr4/2 ls w/sb/vf fi/co;c/fe 13 1e 7-17 cw 10yr6/3 ls w/sb/vf vfi-fi/fe 18 2a 17-31 cw 10yr5/4 sl/ls m/sb/vf vfi/vfe;c/vfe 21 2e1 31-61 gi 10yr6/3 ls/s w-m/sb/vf vfi/vfe 22 2e2 61++ gw 10yr5/4 ls w-m/sb/vf n 21 belukar ii o +6-0 litterfall with rootmat layers a 0-21 c-gw 10yr5/6 sicl w/sb/f vfi-fi/c;me-c/fe 12 b1 21-39 g-dw 10yr6/6 sic m/sb/f vfi-fi/vfe;me-c/vfe 18 b2 39-66 gw 7.5yr6/8 c s/sb/me-c vfi/vfe;me/vfe 20 bc 66++ gw 7.5yr7/8 c ma n 21 abbreviations: a) g=gradual, c=clear, d=diffuse, w=wavy, i=irregular ; b) sl=sandy loam, scl=sandy clay loam, ls=loamy sand, sc=sandy clay, s=sand, sicl=silty clay loam, sic=silt clay, c=clay; c) w=weak, m=moderate, s=strong, sb=sub-angular blocky, ma=massive, vf=very fine, f=fine, me=medium, c=coarse; d) vfi=very fine; fi=fine; me=medium; c=coarse; n=none; vfe=very few; fe=few; co=common; e) hardness was measured using a yamanaka-type penetrometer. differences in soil morphological properties under secondary forests could be observed under different stages of fallow period. the soil texture showed the differences among the soil profiles in the study sites in terms of “feel” method observation. these differences were also distinctive when the colour for each horizon between the soils profiles was compared. the differences in soil colour for each soil profile indicate the amount of organic matter in the soil, which is generally well correlated with the soil fertility and decomposition level (fisher & binkley, 2000). relative differences on the soil structure and root as well as the soil hardness were observed in each soil profile. some differences may probably be due to shifting cultivation activity before abandoning the lands. a number of soil morphological attributes may affect soil development process under the succession process: soil texture (size distribution of particles), structure (arrangement of soil particles), depth of each soil horizons, penetration of roots from above vegetation and soil hardness with increasing soil depth as well as accumulation of litter fall at surface soils. the accumulation 33 of litter fall at surface soils will lead to large amount of organic matter pool at the surface soil horizon. organic matter that normally accumulates under forest provides an environment for higher microbial activities (simmonds, 1972; oriola et al., 2010). moreover, the organic matter is highly influenced by the plant cover as this generates the litter that constitutes its major raw material. as for the case in this study, the increase of o horizon layer with increasing fallow period will lead to the increase in the organic matter content at forest floor surface which can be attributed to the larger foliage cover of forest helps to reduce the impact of soil erosion in removing surface organic matter (oriola et al., 2010). during early stage secondary succession of fallow lands after shifting cultivation, the floristic composition was dominated and obtained by many similar species in temuda i, temuda ii, and belukar i. however, belukar ii showed relatively different species composition among all study sites. this showed that species composition at abandoned lands after burning begin to change after 20 years of abandonment (karyati et al., 2013). the above vegetation is important source to organic matter accumulation. the differences of vegetation composition may lead to differences in organic matter accumulation at different fallow ages in four study sites. 3.2. soil physicochemical properties under various stages of secondary forests the soil physicochemical properties at different ages of secondary forests are summarized in table 2. in general, the soils of all study sites were strongly acidic with ph (h2o) values of less than 5 and the low content of t-c and t-n as well as exchangeable bases. this was probably due to the ash effect after burning where accumulation and addition process of nutrient during fallow period derived from the amount of biomass supplied during burning. this was also probably influenced by process of nutrient uptake by vegetation as well as leaching and decomposition process during early succession process. similar pattern in soil ph changes after burning was also reported by etsuko et al. (2004) on tropical soils after slash and burn cultivation at northern laos. during the fallow period, the loss of exchangeable bases from the soils and concomitant soil acidification occur because of leaching and uptake by recovering secondary vegetation (uhl, 1987; tanaka et al., 2007b). the soils at the early stages of secondary forest tended to be less acidic with higher contents of exchangeable ca and mg. this could be ascribed to the remaining effects of ash (juo & manu, 1996; wasli et al., 2009), suggesting that a small ash input under intensified shifting cultivation with a shorter fallow period could still improve soil fertility to some extent (tanaka et al., 2009). the values of t-c and t-n decreased at the depth of 0-10 cm to 20-30 cm at different stages of secondary forests. the similar trend was also reported by feldpausch et al. (2007). the relationships between t-n and c/n ratio at the depth of 0-10 cm in the study sites were displayed by a linear model as illustrated in fig. 2. the content of the soil t-n might be influenced by accumulation process of soil organic matter during, both inputs process from litterfall and output process by decomposition (biological fixation) during the early stages of fallow periods. especially in belukar ii whereby the level of c/n ratio at subsoils (20-30 cm depth) is tended to be higher as compare to other sites, such finding shows that both the quality of soil organic matter and the actual amount of mineral n is substantial as compared to land with younger fallow age. the levels of t-c and cec at 0-10 cm depth showed no significant differences in all study sites, except for soils in belukar ii at 0-10 cm depth. at this site, the levels of t-c, t-n, and cec were the highest. the contents of exchangeable ca, mg, and k were higher at the depth of 0-10 cm than at the depth of 20-30 cm. the exchangeable ca and mg showed no significant difference between temuda i and temuda ii as well as belukar ii, but temuda i and temuda ii were 34 significantly different compared to belukar i and belukar ii at the depth of 0-10 cm. at the same time, exchangeable na of all study sites at 0-10 cm depth showed no significant differences, except in belukar ii. the higher amount of ca corresponds to the higher ph value (etsuko et al., 2004). this trend was similar with the study in secondary forest of amazonian by lu et al. (2002), but contrast with the study of ohta et al. (1993). the contents of exchangeable k were minimum and maximum at the depth of 10-20 cm (e horizon) and 3080 cm (upper b horizon) at lowland dipterocarp forest in east kalimantan, indonesia (ohta et al., 1993). the higher contents of exchangeable ca and mg in the topsoils were due to their biological accumulation through litter supply and their lower mobility in soil (ohta et al., 1993). table 2: physicochemical properties of the soils in the study sites. parameter 0-10 cm (n=9) temuda i temuda ii belukar i belukar ii ph (h2o) 4.71 (0.13) ab 4.50 (0.26) a 4.88 (0.16) b 4.85 (0.14) b ph (kcl) 3.72 (0.24) b 3.59 (0.15) ab 3.43 (0.28) a 3.52 (0.09) ab ec 7.55 (2.05) a 9.18 (1.05) a 8.41 (1.50) a 9.02 (1.79) a t-c 8.0 (0.1) a 8.0 (0.5) a 7.9 (0.4) a 8.5 (0.4) b t-n 0.52 (0.01) ab 0.53 (0.08) ab 0.48 (0.05) a 0.57 (0.04) b c/n ratio 15.4 (0.2) ab 15.3 (1.68) ab 16.7 (1.8) b 14.8 (1.2) a cec 12.6 (3.50) a 20.6 (6.8) a 16.9 (6.6) a 39.1 (11.3) b exch-ca 0.04 (0.02) a 0.13 (0.04) a 0.53 (0.26) b 0.41 (0.17) b exch-mg 0.05 (0.03) a 0.08 (0.05) a 0.21 (0.11) b 0.17 (0.06) b exch-k 0.05 (0.03) a 0.07 (0.04) a 0.08 (0.05) ab 0.12 (0.02) b exch-na 0.02 (0.01) a 0.02 (0.01) a 0.03 (0.02) a 1.58 (0.33) b clay 15.7 (4.6) a 13.9 (3.1) a 15.9 (7.6) a 30.2 (4.0) b silt 11.6 (5.4) b 7.6 (1.9) ab 4.7 (2.8) a 19.3 (4.9) c sand 72.7 (9.1) b 78.4 (4.6) b 79.4 (9.6) b 50.5 (7.5) a bulk density 1.09 (0.16) bc 1.11 (0.08) c 0.94 (0.16) ab 0.86 (0.09) a porosity 0.59 (0.06) ab 0.58 (0.03) a 0.65 (0.06) bc 0.68 (0.03) c parameter 20-30 cm (n=9) temuda i temuda ii belukar i belukar ii ph (h2o) 4.81 (0.09) ab 4.63 (0.20) a 4.89 (0.14) b 4.87 (0.15) b ph (kcl) 3.73 (0.16) a 3.81 (0.14) a 3.89 (0.10) a 3.74 (0.16) a ec 6.50 (1.46) a 6.26 (2.11) a 4.92 (1.20) a 7.36 (2.59) a t-c 6.9 (0.1) a 7.1 (0.3) a 7.43 (0.88) a 7.3 (0.2) a t-n 0.51 (0.06) a 0.50 (0.08) a 0.53 (0.11) a 0.48 (0.03) a c/n ratio 13.7 (1.5) a 14.5 (2.3) a 14.4 (2.7) a 15.1 (0.9) a cec 14.9 (8.0) a 16.1 (6.4) a 12.1 (4.7) a 18.6 (6.3) a exch-ca 0.08 (0.05) ab 0.03 (0.02) a 0.22 (0.17) b 0.23 (0.18) b exch-mg 0.02 (0.02) a 0.02 (0.02) a 0.05 (0.04) a 0.05 (0.03) a exch-k 0.02 (0.02) a 0.01 (0.01) a 0.05 (0.03) b 0.06 (0.02) b exch-na 0.02 (0.02) a 0.02 (0.02) a 1.20 (0.26) b 0.05 (0.02) a clay 18.2 (4.6) b 22.0 (7.4) b 8.3 (3.2) a 45.2 (9.0) c silt 8.8 (4.8) ab 13.1 (3.7) bc 4.1 (2.8) a 16.6 (4.9) c sand 73.0 (9.1) b 64.9 (9.9) b 87.6 (5.3) c 38.2 (4.6) a bulk density 1.45 (0.12) ab 1.36 (0.16) ab 1.52 (0.14) b 1.31 (0.12) a porosity 0.45 (0.04) ab 0.48 (0.06) ab 0.42 (0.05) a 0.50 (0.05) b ec=electrical conductivity (µs); t-c=total carbon and t-n=total nitrogen (%); cec=cation exchange capacity, exch-ca, exch-mg, exch-k, and exch-na = exchangeable calcium, exchangeable magnesium, exchangeable potassium, and exchangeable natrium (cmolc kg -1 ); clay, silt, sand, and porosity in percentage (%); bulk density in (g ml -1 ). values are average and standard deviation (sd) in parentheses. different letters in each line indicate a significant difference at 5% level by tukey’s test among different ages of secondary forests. 35 fig. 2: relationship between total n and c/n ratio at the depth of 0-10 cm in the study sites. temuda i (y=-0.03x+0.98, r 2 =0.68), temuda ii (y=-0.04x+1.20, r 2 =0.86), belukar i (y=0.03x+0.91, r 2 =0.77), and belukar ii (y=-0.03x+0.96, r 2 =0.74). table 2 showed that exchangeable ca, mg, k, and sum of exchangeable bases tended to increase with an increased in fallow age. accumulation of soil organic matter during the fallow period and ash deposits from the burned biomass are the main factors contributing to increased soil fertility at the end of the fallow period. the biomass of the fallow vegetation is generally a major pool for potassium, calcium and magnesium (nye & greenland, 1960; jordan, 1985: andriesse & scbelbaas, 1987b; sanchez, 1987). in contrast, soil concentration of exchangeable ca decreased with increasing stand age in primary and secondary forests in eastern amazônia, while soil concentration of exchangeable mg were higher in all secondary plot soils than in the primary plot soil (johnson et al., 2001). the distribution pattern of exchangeable ca in the study sites showed a similar trend with exchangeable mg. on the other hand, exchangeable na did not show any relationships in term of the fallow periods. this trend was in line with study as reported by etsuko et al. (2004). the contents of clay and sand at surface soils (0-10 cm depth) showed no significant differences in all study sites, except for belukar ii. the content of sand in the soils of belukar ii was the highest among all study sites, meanwhile the lowest content of sand was also observed at the depth of 0-10 cm in this site. however, there was a significant relationship between the soil clay and sand contents at the depth of 0-10 cm in these study sites as illustrated in fig. 3. the bulk density was higher at the depth of 20-30 cm than at the depth of 0-10 cm. the lower bulk density usually showed the higher porosity. generally, the higher bulk density indicated the compaction of soil in the site. similarly, ohta and effendi (1992a) observed that bulk density increased with depth, and was inversely correlated with the clay and carbon contents in each horizon at lowland dipterocarp forest in east kalimantan, indonesia. soils at 0-10 cm depth was harder than at 20-30 cm depth. at the depth of 0-10 cm, the soil hardness decreased with increasing fallow periods. on the other hand, unclear difference were observed for the soil hardness at different depths in the study sites as shown in table 1. this indicated that the soil hardness at different depth was not relatively changed at the early stage of secondary succession process till 20 years fallow period. this may probably be due to the variation of soil texture and porosity under the similar parent materials. the soil hardness was significantly high probably because of the dead and carbonized tree roots of the former vegetation (ogino et al., 2000). 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0 5 10 15 20 25 t o ta l n ( % ) c/n ratio temuda i temuda ii belukar i belukar ii 36 fig. 3: relationship between sand and clay contents at the depth of 0-10 cm in the study sites. temuda i (y=-1.76x+100.37, r 2 =0.80), temuda ii (y=-1.41x+98.13, r 2 =0.90), belukar i (y=-1.23x+98.93, r 2 =0.95), and belukar ii (y=-1.47x+94.85, r 2 =0.63). 4. conclusion this study indicated that soil physiochemical properties differed at different stages of fallow lands (3, 5, 10, and 20 years old secondary forests) as well as at different soil depths (0-10 cm and 20-30 cm depths). under similar parent material and land use history (slash and burn), several soil physicochemical properties showed significant differences among the different ages of secondary forests after abandonment. this indicated that the soil morphological and physiochemical properties developed and changes at early secondary succession process following fallow period. the development and changes of species composition of plant seedlings and saplings after slash and burn process was mostly influenced by secondary succession process and fallow age in abandoned lands (karyati et al., 2013). in addition, the fallowing period of 20 years was probably insufficient to allow fallow lands to recover vegetation and soil parameters which could increase the high ability to provide sufficient in both above ground and below ground biomass as well as c stock in vegetation and soil (karyati, 2013). the information on forest soil properties is important and critical to understand the change and dynamic process under various stages of secondary forests. the comprehensive understanding about soil properties and development process is useful for addressing future management of secondary forests and the related issues like global climate change, biodiversity, carbon marketing and sustainability of ecosystem service of secondary forests. acknowledgements we acknowledge to malaysian palm oil board (mpob) for supporting the funding of this research project. we thank all support staff at faculty of resource science and technology, universiti malaysia sarawak, en. hidir marzuki, en. sekudan tedong, en. salim arip and en. muhd najib fardos for their field assistance and companionship during the survey. 0 10 20 30 40 50 60 70 80 90 100 0 5 10 15 20 25 30 35 40 s a n d ( % ) clay (%) temuda i temuda ii belukar i belukar ii 37 references abebrese, m.o., 2002. tropical secondary forest management in africa. in: workshop on tropical secondary forest management in africa: reality and perspectives, 9-13 december 2002. kenya: nairobi, pp.1-7. andriesse , j.p., schelhaas, r.m., 1987a. a monitoring study on nutrient cycles in soils used for shifting cultivation under various climatic conditions in tropical asia. iii. the effects of land clearing through burning on fertility level. agriculture, ecosystems & environment, 19:311-332. andriesse , j.p., schelhaas, r.m., 1987b. a monitoring study of nutrient cycles in soils used for shifting cultivation under various climatic conditions in tropical asia. ii. nutrient stores in biomass and soil results of baseline studies. agriculture, ecosystems & environment, 19:285-310. butt, g., 1983. semi-detailed site evaluation of sabal forest reserve northern half. forest research report no. s.s.2. soil survey unit, research section, forest department, sarawak. etsuko, w., katsutoshi, s., yukoh, o., nouanthasing, l., chanphengxay, a., 2004. soil fertility and farming systems in a slash and burn cultivation area of northern laos. southeast asian studies, 41(4):519-537. feldpausch, t.r., prates-clark, c.c., fernandes, e.c.m., riha, s.j., 2007. secondary forest growth deviation from chronosequence predictions in central amazonia. global change biology, 13:967-979. fisher, r.f., binkley, d., 2000. ecology and management of forest soils, 3 rd john wiley & sons, inc, usa. harris, r. w., 1992. arboriculture: integrated management of landscape trees, shrubs and vines. prentice hall career & technology, new jersey. hazra, p., som, m.g., 2006. vegetable science. kalyani publishers, new delhi. johnson, c.m., vieira, i.c.g., zarin, d.j., frizano, j., johnson, a.h., 2001. carbon and nutrient storage in primary and secondary forests in eastern amazônia. forest ecology & management, 147:245-252. johnson, e.a., miyanishi, k., 2007. disturbance and succession, in: johnson, e.a., miyanishi, k. (eds.), plant disturbance ecology: the process and the response, elsevier, usa, pp.1-14. jomo, k.s., chang, y.t., khoo, k.j., 2004. deforesting malaysia: the political, social ecology of agricultural expansion and commercial logging. zed books ltd., united kingdom. jordan, c.f., 1985. nutrient cycling in tropical forest ecosystem. wiley, new york. juo, a.s.r., manu, a., 1996. chemical dynamics in slash-and-burning agriculture. agriculture, ecosystems & environment, 58:49-60. karyati, ipor, i.b., jusoh, i., wasli, m.e., 2012. suitability of plant species for agroforestry program at sri aman, sarawak. in: ahmad, f.b., muid, s., ipor, i.b., zainudin, r., wasli, m.e., kalu, m., assim, z.b. (eds.), taxonomy and ecology: beyond classical approaches. universiti malaysia sarawak, malaysia, pp.203-213. karyati, 2013. ecology and carbon sequestration of secondary forests at sabal, sarawak. phd thesis, universiti malaysia sarawak. karyati, ipor, i.b., jusoh, i., wasli, m.e., 2013. composition and diversity of plant seedlings and saplings at early secondary succession of fallow lands in sabal, sarawak. acta biological malaysiana, 2(3):85-94. 38 keddy, p.a., 2007. plants and vegetation: origins, processes, consequences. cambridge university press, new york. kendawang, j.j., ninomiya, i ., tanaka, k., ozawa, t., hattori, d., tanaka, s., sakurai, k., 2007. effects of burning strength in shifting cultivation on the early stage of secondary succession in sarawak, malaysia. tropics, 16:309-321. lamb, d., erskine, p.d., parrotta, j.a., 2005. restoration of degraded tropical forest landscapes. science, 310:1628-1632. lanly, j.p., 1982. tropical forest resources. fao forestry paper 30. fao, rome, italy. latiff, a., zakri, a.h., 1998. environmental and conservation issues in malaysia, in ismail, g., mohamed, m. (eds.), biodiversity conservation in asia: emerging issues and regional needs. asean academic press, london, pp.138-164. lu, d., mausel, p., moran, e., 2002. linking amazonian secondary succession forest growth to soil properties. land degradation & development, 13:331-343. misra, k.c., 1992. manual of plant ecology. raju primlani, new delhi. mittelman, a., 2001. secondary forests in the lower mekong sub-region: an overview of their extent, roles and importance. journal of tropical forest science, 13(4):671-690. nakano, k., miyauchi, n., 1996. changes in physical and chemical properties of surface soil in a swidden and subsequent fallow in a northwestern region of malaita island, solomon islands. south pacific study, 17(1):1-20. nrcs, 2002. field book for describing and sampling soils, version 2.0. in: schoeneberger, p.j., wysocki, d.a., benham, e.c., broderson, w.d. (eds.), natural resources conservation service, national soil survey centre, lincoln, ne. nye, p.h., greenland, d.j., 1960. the soil under shifting cultivation. commonwealth bureau of soils technical communication no.51. commonwealth agricultural bureau, farnham. ogino, k., lee, h.s., kendawang, j.j., 2000. proceedings of workshop on forest ecosystem rehabilitation. forest department sarawak, sarawak. ohta, s., effendi, s., 1992a. ultisols of lowland dipterocarp forest in east kalimantan, indonesia i. morphology and physical properties. soil science & plant nutrition, 38(2):197-206. ohta, s., effendi, s, 1992b. ultisols of lowland dipterocarp forest in east kalimantan, indonesia ii. status of carbon, nitrogen, and phosphorus. soil science and plant nutrition, 38(2):207-216. ohta, s., effendi, s., tanaka, n., miura, s., 1993. ultisols of lowland dipterocarp forest in east kalimantan, indonesia iii. clay minerals, free oxides, and exchangeable cations. soil science & plant nutrition, 39(1):1-12. oriola, e.o., ifabiyi, i.p., hammed, a.t., 2010. impact of reforestation in a part of degrading natural ecological system of ilorin, kwara state, nigeria. african journal of agricultural research, 5(20):2811-2816. ramakrishnan, p.s., kushwaha. s.p.s., 2001. secondary forests of the himalaya with emphasis on the north-eastern hill region of india. journal of tropical forest science, 13(4):727-747. sanchez, p.a., 1987. management of acid soils in the humid tropics of latin america, in proceedings of an ibsram inaugural workshop: management of acid tropical soils for sustainable agriculture, bangkok, pp.63-107. schedlbauer, j.l., kavanagh, k.l., 2008. soil carbon dynamics in a chronosequence of secondary forests in northeastern costa rica. forest ecology & management, 255:1326-1335. 39 simmonds, n.w., 1972. the evolution of the bananas. longman publication, london. soil survey staff, 1994. keys to soil taxonomy. 6 th ed. u.s. department of agriculture & soil conservation service, washington, dc. soil survey staff, 2006. keys to soil taxonomy. 10 th ed. u.s. department of agriculture & natural resources conservation service, washington, dc. tanaka, s., wasli, m.e., seman, l, lee, a., kendawang, j.j., sakurai, k., morooka, y., 2007a. ecological study on site selection for shifting cultivation by the iban of sarawak, malaysia. a case study in the mujong river area. tropics, 16(4):357-371. tanaka, s., wasli, m.e., seman, l, lee, a., kendawang, j.j., sakurai, k., morooka, y., 2007b. soil properties of secondary forests under shifting cultivation by the iban of sarawak, malaysia in relation to vegetation condition. tropics, 16(4):385-398. tanaka, s., tachibe, s., wasli, m.e., lat, j., seman, l., kendawang, j.j., iwasaki, k., sakurai, k., 2009. soil characteristics under cash crop farming in upland areas of sarawak, malaysia. agriculture, ecosystems & environment, 129:293-301. teng, s.c., 1993. keys to soil classification in sarawak. technical paper 10. soils division, research branch, department of agriculture, sarawak. uhl, c., 1987. factors controlling succession following slash-and-burn agriculture in amazonia. journal of ecology, 75:377-407. van do, t., osawa, a., thang, n.t., 2010. recovery process of a mountain forest after shifting cultivation in northwestern vietnam. forest ecology & management, 259:1650-1659. wasli, m.e. tanaka, s., kendawang, j.j., seman, l., unang, b., lat, j., abdu, a., morooka, y., sakurai, k., 2009. vegetation conditions and soil fertility of fallow lands under intensified shifting cultivation systems in sarawak, malaysia. tropics, 18(3):115-126. whitmore, t.c., 1975. tropical rain forests of the far east. oxford university press, united kingdom. abdullahalmamun et al. /journal of tropical forestry and environment vol. 5. no 01 (2015) 83-93 83 effect of household solid waste on initial growth performance of acacia auriculiformis and cedrela toona in mycorrhiza inoculated soil m.m. abdullah-al-mamun 1* , m. billah 2 , m.a. hossain 1 and m. alamgir 1 1 institute of forestry and environmental sciences, university of chittagong, chittagong-4331, bangladesh 2 crel project, winrock international, south-west regional office, khulna-9100, bangladesh date received: 08-01-2015 date accepted: 31-03-2015 abstract solid waste disposal and management became one of the major environmental concerns in bangladesh. realising the problem, the present study has been undertaken with a view to find a sound and effective way of bio-degradable solid waste management. the study was carried out in the nursery of institute of forestry and environmental sciences at university of chittagong to determine the effects of solid waste and waste inoculated with mycorrhizal soil on initial growth performance of acacia auriculiformis and cedrela toona. before planting the seedlings, decomposable waste and mycorrhiza inoculated decomposable waste were placed on the planting holes. physical growth parameters of seedlings (shoot and root length, leaf and branch number, fresh and dry weight of shoot and root and nodulation status) and the macro nutrients (n, p and k) were recorded after six months of planting. the highest performance of physical parameters was recorded in the soil treated by mycorrhiza inoculated waste. cedrela toona was represented by maximum nutrients uptake (n-2.60%, p-0.21% and k-2.34% respectively) in the soil treated with mycorrhiza. in case of acacia auriculiformis, n uptake was maximum (3.02%) in control while k uptake was highest (1.27%) in soil with waste and p (0.18%) uptake was highest in the soil treated with mycorrhiza inoculated waste. highest initial growth performance was revealed by seedlings treated with mycorrhiza inoculated waste. this study suggested to use mycorrhiza and waste for plantation purposes for hygienic disposal of solid waste and to reduce cost of cultivation. keywords: solid waste, mycorrhiza, growth performance, cedrela toona, acacia auriculiformis. 1. introduction urban solid waste management (swm) is considered to be one of the most serious environmental problems confronting urban areas especially in developing countries like bangladesh (sinha and enayetullah, 2000; sujauddin et al., 2007). according to available statistics, 16,380 tons of waste gets produced in bangladesh per day. municipal authorities are generally responsible for swm * correspondence: mamun@cu.ac.bd tel: +88 1712100611 issn 2235-9370 print/issn 2235-9362 online © university of sri jayewardenepura in bangladesh (sujauddin et al., 2007). however, municipal services in most cities and towns are already over-burdened and simply cannot cope with the growing demand owing to insufficient manpower 84 man power and materials, resulting in unhygienic and filthy living condition in the neighborhood (kumar and bhowmick, 1998; enayetullah et al., 2005). however, many of these waste materials can be reused (kumar and bhowmick, 1998) and eventually become valuable resources (world bank, 1999). among the different types of solid wastes, residential or household waste represents about 30% of the overall municipal waste stream and the urban residents generate two to three times as much solid waste as their fellow rural citizens in asia (world bank, 1999). a substantial portion (69-77%) of solid waste in the urban areas of bangladesh is compostable (includes food, vegetable, rags, jute, wood, grass, leaves, etc.). however, the most potential source of compostable waste is residential or household solid waste (enayetullah et al., 2005; sujauddin et al., 2007). organic materials in solid waste contain nutrients for crop growth and also improve soil filth, increase water holding capacity, lessen water and wind erosion, improve aeration, and promote soil biological activity. supplementing the nutrient requirement of crops through organic fertilizer such as crop residues, manures and compost plays a key role in sustaining soil fertility and crop productivity. in most part of the tropics, socio-economic constraints and lack of scientific knowledge or adequate system of management of soil fertility push most of the farmers to little or no use of fertilizers. rahman et al.(2006) reported that the moisture content, ph, organic matter, organic carbon, nitrogen and c/n in the residential area range between 25.38-34.13, 6.2-7.2, 35.75-43.03, 24.89-30.11, 1.43-1.91 and 15-19, respectively. moreover, according to holmer (2002), the c/n was found 13-23, 11-13, 40-60, 9-25 in kitchen waste, vegetable wastes, leaves, grass, respectively. the application of residential or household organic solid waste can be a potential alternative of expensive chemical fertilizers and thus eventually a sustainable mean of swm (sujauddin et al., 2007). mycorrhiza allowed the plants to derive more nutrients and enhance plant growth. similar study was conducted by marschner and dell (1994) and clark and zeto (2000) stated that mycorrhizal fungi can overcome nutrient limitation to plant growth by enhancing nutrient acquisition, especially phosphorus. robson et al., (1981) reported that mycorrhiza have the potential to uptake of most essential nutrients. p acts as a stimulator of plant growth and plays a vital role in nodule formation. the effects of p on nodulation and nitrogenous activity were often ascribed to a general stimulation via plant growth (jakobsen, 1985; yang, 1995; reddell et al., 1997). however, some investigations suggested that p had a specific stimulation on different plant nodulations (israel, 1987; hellsten and huss-danell, 2000). vallini and pera (1989) examined plant growth by application of mature compost in soil. but the application of fresh organic solid waste as a stimulating agent for plant growth has not yet been undertaken. owing to this, the present study was an attempt to evaluate the plant growth and essential nutrients uptake by forest crops applying fresh household organic waste as an alternative option for conventional swm. to observe the initial growth performance and macro nutrient uptake of acacia auriculiformis and cedrela toona using the household solid waste inoculated with mycorrhizal soil were the aim of this research. 2. materials and methods the experiment was carried out in the nursery of the institute of forestry and environmental sciences, chittagong university (ifescu), bangladesh. experimental plot of 5×3 m 2 size was designed. the plot was divided into two subplots with 1 m spacing between two subplots. living roots infected with mycorrhizal fungi and different types of glomus species in the soil were used as inoculums. the fungus infected root were sliced into small pieces with scissors and mixed thoroughly abdullahalmamun et al. /journal of tropical forestry and environment vol. 5. no 01 (2015) 83-93 85 with the soil. the mixture was then used as mycorrhizal inoculums in waste. solid wastes were collected from the residential area of chittagong university campus, which then segregated into decomposable and non-decomposable waste. the decomposable waste included the residue of vegetables, paper, packaging material, fish residue, fruits residue, straw, etc. the seedlings were collected from the nursery of ifescu. two first growing species akashmoni (acacia auriculiformis) and toon (cedrela toona) were selected for the experiment. three treatments were designed as t0control, t1-soil with waste and t2-soil with mycorrhiza inoculated waste for the experiment. size of each hole in the experimental plot was 30 cm in depth and 30 cm in diameter. the decomposable solid wastes were placed into the hole with bucket. 6 kg waste was used in each hole. in case of treatment t2, at first 1 kg of waste was poured into the hole with the help of a bucket and then two inch layer of soil containing living roots infected with mycorrhizal fungi and different types of glomus species were placed. for treatment t1 only soil was used in between the waste layers. the same process was repeated twice and finally the holes were covered with two inch layer of soil. after that the seedlings were planted. watering was carried out regularly in the morning. regular removal of weeds, grasses etc. were done as far as possible. partial shade and covering was provided to protect the seedlings from strong sunlight and rain. morphological parameters of the seedlings, i.e. height, collar diameter and leaf number, were recorded before planting in the experiment plot. the seedlings were allowed to grow for five months from the time of planting. after six months, seedlings were harvested and morphological parameters of shoot and root length, collar diameter, leaf number, branch number, nodulation status, fresh weight of leaves and the same of shoot and root were recorded. leaf, shoot and root were dried in the oven at a temperature of 70 0 c for 24 hours. finally the dry weight of leaf, shoot and root were recorded. the leaves were then grind in such that the leaves became powdery and then allowed to pass through sieve. the sieved leaves were then ready for determining nutrient status. phosphorous was measured by olsen’s method; potassium was determined by flame photometer; and nitrogen was determined by micro-kjeldhal digestion process (jackson, 1973). the data obtained in respect of different treatments were tested with anova to find out the growth variations at 5% significant level. 3. results and discussion 3.1 fresh and dry weight of shoot, root and leaves of acacia auriculiformis the highest fresh weight of shoot was found 598 g whereas the lowest was found 257 g (figure 1). fresh weight of shoot was recorded highest in t2 and lowest in t1. in case of dry weight better result was recorded also in t2 and it was 262 g whereas the lowest (242 g) dry weight of shoot was found in t0. in case of fresh weight, significant difference was found in between t0 and t1 and in between t0 and t2. but no significant difference (at 5% significance level) was found in between t1 and t2 whereas, dry weight values of all the treatments t0, t1 and t2 were significantly different. the highest fresh weight of root was recorded 204 g whereas the lowest fresh weight of root was found 81 g (figure 2). fresh weight of root was recorded highest in t2 and lowest in t1. in case of dry weight, better result was recorded also in t2 and it was 69 g whereas the lowest dry weight of root was found in t0 and it was 28 g. significant difference was found in the fresh weight values between t0 and t1 but no significant difference found between t1 and t2. in case of dry weight, significant differences were recorded among all the treatments (t0, t1 and t2). 86 0 50 100 150 200 250 t0 t1 t2 l e n g th ( c m ) treatments shoot height root length the highest fresh weight of leaf was recorded 790 g in t2, whereas the lowest fresh weight of leaf was observed 340 g in t0 (figure 3). similarly better result for dry weight of leaf was recorded also in t2 (102 g) whereas the lowest was found in t0 (83 g). in case of fresh weight significantly variation was found between t0 and t1. significantly difference was also recorded between t1 and t2. in case of dry weight no significant result was recorded among the treatments t0, t1 and t2. of 0 100 200 300 400 500 600 700 t0 t1 t2 w e ig h t treatments fresh weight dry weight 0 50 100 150 200 250 t0 t1 t2 w e ig h t treatment fresh weight dry weight 0 100 200 300 400 500 600 700 800 900 t0 t1 t2 w e ig h t treatments fresh weight dry weight figure 1: fresh and dry weight of shoot of acacia auriculoformis. figure 2: fresh and dry weight of root of acacia auriculiformis. figure 3: fresh and dry weight of leaf of acacia auriculiformis. figure 4: root length and shoot height of acacia auriculiformis. abdullahalmamun et al. /journal of tropical forestry and environment vol. 5. no 01 (2015) 83-93 87 0 100 200 300 400 500 600 nodule brach number leaf n u m b e r leaf, branch & nodule t0 t1 t2 3.2 root length and shoot height of acacia auriculiformis the highest performance of shoot height was recorded 220.40 cm in t2, whereas the lowest shoot height was recorded 188.60 cm in t0 (figure 4). in case of root length better result was recorded also in treatment t2 (66.60 cm), whereas the lowest dry weight of root was found in treatment t0 (46 cm). 3.3 number of leafy branch and nodule of acacia auriculiformis the highest number of leaf was recorded 530.80 in t2 whereas the lowest number of leaf was found 234.80 in t1 (figure 5). in case of branch number better result was recorded in treatment t1 and it was 33.80 whereas the lowest number of leaf was observed in t0 (17.60). nodule number was found the highest in treatment t2 (208) while the lowest number of nodule was recorded in treatment t0 (91). in case of leaf number and branch number no significant result was recorded among the treatments. but nodule number varied significantly in between treatments t0 and t1 and in between t0 and t2. 3.4 percentage of n, p and k percentage of nitrogen uptake was found the highest in treatment t0 (3.02%) and the lowest in treatments t2 (2.88%) (figure 6). nitrogen uptake did not vary significantly among the treatments. phosphorus uptake was highest in treatment t2 (0.18%) and lowest in treatment t0 (0.15%). potassium uptake was highest in treatments t1 (1.27%) and lowest in treatment t0 (0.82%). nitrogen uptake did not vary significantly among the treatments. but the potassium uptake varies significantly among the treatments t0, t1 and t2. 3.5 fresh and dry weight of shoot, root and leaves of cedrela toona the highest fresh weight of shoot was recorded 880 g in t2, whereas the lowest fresh weight of shoot was found 738 g in t0 (figure 7). in case of dry weight better result was recorded also in t2 and it was 406 g. no significant result was observed in among the treatments. 0 0.5 1 1.5 2 2.5 3 3.5 n(%) p(%) k(%) p e rc e n ta g e n, p & k t0 t1 t2 figure 5: number of leaf branch and nodule of acacia auriculiformis. figure 6: percentage of n, p and k of acacia auriculiformis. 88 t the highest fresh weight of root was recorded 658 g in t2, whereas the lowest fresh weight of shoot was calculated 424 g in t0 (figure 8). in case of dry weight better result was recorded also in t2 and it was 308 g. no significant result was observed among the treatments. the highest fresh weight of leaf was recorded 482 g in t2 whereas the lowest fresh weight of leaf was recorded 326 g in t0 (figure 9). in case of dry weight better result was recorded also in t2 (222 g), whereas the lowest in t0 (144 g). no significant result was observed among the treatments. 3.6 root length and shoot height of cedrela toona highest performance of shoot height was recorded 268.40 cm in treatment t1, whereas the lowest shoot height was found 240.2 cm (figure 10). in case of root length better result was recorded in treatment t2 (82.40 cm), whereas the lowest dry weight of root was observed in treatment t0 (66.20 cm). in case of shoot height, significant result was found among the three treatments, whereas no significant difference was found in root height among the treatments. 0 100 200 300 400 500 600 t0 t1 t2 w e ig h t treatments fresh weight dry weight 0 50 100 150 200 250 300 t0 t1 t2 l e n g th (c m ) treatments shoot height root length 0 100 200 300 400 500 600 700 800 900 1000 t0 t1 t2 w e ig h t treatments fresh weight dry weight 0 100 200 300 400 500 600 700 t0 t1 t2 w e ig h t treatments fresh weight dry weight figure 7: fresh and dry weight of shoot of cedrela toona. figure 8: fresh and dry weight of root of cedrela toona. figure 10: root length and shoot height of cedrela toona. figure 9: fresh and dry weight of leaf of cedrela toona. abdullahalmamun et al. /journal of tropical forestry and environment vol. 5. no 01 (2015) 83-93 89 3.7 number of leaf and branch of cedrela toona the highest number of leaf was recorded 1059.80 in t2 whereas the lowest number of leaf was found 840.00 in t0 (figure 11). in case of branch number better result was recorded in treatment t2 and it was 44.80. in case of leaf number and branch number no significant difference was found among the treatments. 3.8 percentage of n, p and k of cedrela toona percentage of nitrogen uptake was the highest in treatments t2 and it was 2.60%. nitrogen uptake was lowest in treatments t1 and it was 2.20% (figure 12). nitrogen uptake varies significantly among the treatments. phosphorus uptake was highest in treatment t2 (0.21 %) and lowest in treatment t0 (0.16%). potassium uptake was highest in treatment t2 (2.34%) and lowest in treatment t0 (1.05%). nitrogen, potassium and phosphorus uptake vary significantly among the treatments. 4. discussion in this study it is clearly found that the application of solid waste increases the overall plant growth. cheung et al. (2000) observed more plant productivity in sewage sludge compost-amended lagoon ash in compared with vermiculite because compost can contribute large amount of plant nutrients. the major morphological criteria used to describe the seedling quality are shoot height and root length. height and stem diameter increment are good traits for selecting leguminous plant (duguma and tonye, 1994). consequently these morphological indicators of plant were found correlated with the effect of solid waste inoculated with mycorrhizal soil. mycorrhiza is mutualistic associations between fungi and plant roots. they are described as symbiotic because the fungus receives photosynthetically derived carbon compounds and the plant has increased access to mineral nutrients (brundrett et al., 1996). the solid wastes that are placed in the experimental hole were decomposed gradually. as a result the nutrients become available to the plants and showed better growth. mistry et al. (2003) reported better biomass growth in the experiments of organic manure on 0 200 400 600 800 1000 1200 t0 t1 t2 n u m b e r treatment number leaf number branch 0 0.5 1 1.5 2 2.5 3 n(%) p(%) k(%) p e rc e n ta g e n, p & k t0 t1 t2 figure 12: percentage of n, p and k of cedrela toona. figure 11: number of leaf & branch cedrela toona. 90 tomato yield. lloyd (2002) showed that most of the total nitrogen pool tied up by the soil microbes but the proportion immobilized by the microbes was higher in plots mulched with pellets than in the bare soil or composed yard waste. baduruddin et al. (1999) assessed that wheat yield was better in the plots where organic fertilizer was applied in the form of farm yard manure. mycorrhiza allowed the plants to derive more nutrients and enhance plant growth. present study revealed that fresh and dry weight of shoot was higher in treatment treated with mycorrhizal soil both in acacia auriculiformis and cedrela toona. many other experiments have shown that mycorrhizal fungi can overcome nutrient limitation to plant growth by enhancing nutrient acquisition, especially phosphorus (marschner and dell, 1994; clark and zeto, 2000). in the present study nodule number was found better in soil with waste (t1) and in soil with waste inoculated with mycorrhiza (t2) than the control (t0). similar result was also stated by iqbal et al. (2007). in their study it was revealed that nodulation status and growth parameters were varied significantly in the soil amended with sludge in comparison to control. they found that the highest number of nodule was recorded from soil amended with residential sludge (1:1). in case of growth parameters, the highest growth was recorded from soil and residential sludge (1:1) combination compared to control. leaf number and number of branch were found higher in treatment with waste and highest performance was observed in treatment treated with waste and mycorrhiza. mycorrhiza accelerate nutrient uptake especially phosphorus. the results are in accordance with the findings of jasper et al., 1989 and guissou et al., 1998. it has been established that in p-deficient soil mycorrhizas is an important factor for successful establishment of acacia spp. (jasper et al., 1989). this symbiotic association enhances the growth and the mineral nutrition of the host plant (guissou et al., 1998). plant growth in terms of shoot height, root length and nodulation status were observed best in treatment t2 (waste inoculated with mycorrhiza). the mycorrhiza provides p to plants which acts as a stimulator of plant growth and plays a vital role in nodule formation. selivanovskaya and latypova, 2006 found the same outcome. they stated that the beneficial effects on the biomass of seedlings and the height of the shoots as well as on the length of the roots of the pine seedlings were greater in plots with composted sludge. plants engaged in symbiotic n2 fixation generally have a high requirement for p (robson 1983; jungk, 1998), which was mainly contributed by high atp requirements for nitrogenase function (ribet and drevon, 1996; al niemi et al.,1997), plus p needs for signal transduction, membrane biosynthesis, and nodule development and function (graham and vance, 2000). p has been shown to increase plant growth and stimulate nodulation in legumes (gates 1974; gates and wilson, 1974; robson et al., 1981; jakobsen, 1985; israel, 1987; hellsten and huss-danell 2000) as well as in other plants (ekblad and huss-danell 1995; yang 1995; reddell et al., 1997). the effects of p on nodulation and nitrogenase activity were often ascribed to a general stimulation via plant growth (robson et al., 1981; jakobsen 1985; yang 1995; reddell et al., 1997). however, some investigations suggested that p had a specific stimulation on different plant nodulations (israel 1987; hellsten and huss-danell 2000). fresh weight of shoot, root and leaf showed better performance in waste inoculated with mycorrhizal soil and soil with waste over control. similar works was done by iqbal et al., 2007. abdullahalmamun et al. /journal of tropical forestry and environment vol. 5. no 01 (2015) 83-93 91 according to his findings growth parameters (shoot and root length, vigor index, collar diameter, leaf number, fresh and dry weight of shoot and root and total dry biomass increment) and nodule formation of seedlings recorded from different combinations of sludge treatments in l. leucocephala varied significantly compared to control. in case of nutrient uptake highest percentage of nitrogen uptake was observed in control in acacia auriculiformis. potassium uptake by acacia auriculiformis was highest in treatment t1 (waste inoculated soil) and by cedrela toona in treatment t2 (waste inoculated with mycorrhiza). mycorrhiza inoculated with the waste provides p to the plants and thus the p uptake was highest in t2. this finding is consistent with the study of marschner and dell, 1994 and clark and zeto, 2000. 5. conclusion large amount of solid waste, generated every day in bangladesh, causes serious environmental hazards. the solid waste management practice should be in such that it should be feasible and economically viable. various human introduced techniques are practiced in bangladesh to use the unwanted and unusable waste in a productive way. the management of solid waste through composting involves high cost and as a result the farmer loses their interest in composting. this study revealed that seedling growth performance in terms of shoot height, root length, number of leaf and branch number and nodulation status was higher in treatment treated with waste and waste inoculated with mycorrhiza over control. in regards of nutrient uptake better performance was observed in treatments treated with waste and mycorrhiza. solid waste contains organic matter and gradually releases macro and micronutrients to plants. it also increases soil filth, boost up the water holding capacity of sandy soil and promotes the growth of earth warms and other beneficial soil organisms which promote plant growth. in addition mycorrhiza provides p to the plants. according to the expert, p accelerates the availability of other nutrients like k and n and ultimately contributes to plant growth. residential waste provides a potential source of nutrients to the forest crops especially fast growing species. so, the farmers could practice this method to ensure the low cost and hygienic disposal of solid waste. it will provide better performance in p deficient soil. this technology can be applied in fellow land planting and in vegetable gardening. the process may be practiced in horticulture and other agricultural crops after proper investigation on those crops. reference al niemi, t.s., kahn, m.l. and mcdermott, t.r. 1997. p metabolism in the bean rhizobium tropici symbiosis. plant physiol, 113: 1233-1242. baudriddin, m. reynolds, m.p. and ageeb, o.a.a. 1999. agron. j., 91: 975-993. brundrett, m., bougher, n., dell, b., grove, t. and malajczuk, n. 1996. working with mycorrhizas in forestry and agriculture. aciar monograph 32, p 374. australian centre for international agricultural research, canberra. cheung, k.c., wong, j.p.k., zhang, z.q., wong, j.w.c. and wong, m.h. 2000. revegetation of lagoon ash using the legume species acacia auriculiformis and leucaena leucocephala. environmental pollution, 109: 75-82. clark, r.b. and zeto, s.k. 2000. mineral acquisition by arbuscular mycorrhizal plants. dugma, b. and tonye, j. 1994. growth of ten multipurpose tree species on acid soil in sangmelina, camerron. agroforestry systems, 27: 107-119. 92 ekblad, a. and huss-danell, k. 1995. nitrogen fixation by alnus incana and nitrogen transfer from a. incana to pinus sylvestris influenced by macronutrients and mycorrhiza. new phytologist, 131: 453-459. enayetullah, i., sinha, a.h.m.m. and khan, s.s.a. 2005. urban solid waste management scenario of bangladesh: problems and prospects. waste concern technical documentation, dhaka, bangladesh, p18. gates, c.t. 1974. nodule and plant development in stylosanthes humilis h.b.k.: symbiotic response to phosphorus and sulphur. australian journal of botany, 22: 45-55. gates, c.t. and wilson, j.r. 1974. the interaction of nitrogen and phosphorus on growth, nutrient status and nodulation of stylosanthes humilis h.b.k. townsville stylo. plant and soil, 41: 325333. graham, p.h. and vance, c.p. 2000. nitrogen fixation in perspective: an overview of research and extension needs. field crops research, 65: 93-106. guissou, t.b.a.m., oud, b.a.j.m., guinko, s. and duponnois, r. 1998. responses of parki biglobosa (jacq.) benth, tamarindus indica l. and zizyphus mauritiana lam. to arbuscular mycorrhizal fungi in a phosphorus-deficient soil. biology and fertility of soils, 26: 194-198. hellsten, a. and huss-danell, k. 2000. interaction effects of nitrogen and phosphorus on nodulation in red clover (trifolium pratense l.). acta agriculturae scandinavica b, 50: 135-142. holmer, r.j. 2002. basic principles for composting of biodegradable household wastes. paper presented at the urban vegetable gardening seminar, sundayag sa amihanang mindanao trade expo, cagayan de oro city, philippines, august 30. iqbal, g.m.a., huda, s.m.s., sujauddin, m. and hossain, m.k. 2007. effects of sludge on germination and initial growth performance of leucaena leucocephala seedlings in the nursery. j. forestry research, 18(3): 226-230. israel, d.w. 1987. investigation of the role of phosphorus in symbiotic dinitrogen fixation. plant physiology, 84: 835-840. jackson, 1973. nitrogen transformation in soil organic matter. technical meeting on the use of isotopes in soil organic matter studies. fao/iaea, brunswick, usa. jakobsen, i. 1985. the role of phosphorus in nitrogen fixation by young pea plants (pisum sativum). physiologia plantarum, 64: 190-196. jasper, d.a., abbott, l.k. and robson, a.d. 1989. acacia auriculiformis respond to additions of phosphorus and to inoculation with va mycorrhizal fungi in soils stockpiled during mineral sand mining. plant and soil, 115: 99-108. jungk, a.o. 1998. dynamics of nutrient movement at the soil-root interface. in: y. waisel et al. (eds.), plant roots: the hidden half. new york: marcel dekker, pp. 529-556. kumar, p.d. and bhowmick, g.c. 1998. solid waste management: the obvious answer. in: roy, d. (ed.), environment management with indian experience. a.p.h. publishing corporation, new delhi, p.173. lloyd, j.h., stinner, e.d.a. and hoitink, b.r. 2002. organic mulches enhance plant growth. marschner, h. and dell, b. 1994. nutrient uptake in mycorrhizal symbiosis. plant and microbial biomass, activity and pine seedlings in nursery forest. waste management, 26: 1253-1258. mistry, k.k., pani, b. and khair, a. 2003. effects of organic manure on yield of tomato in summer season under polythene tunnel. j. annual botanical conference, pp. 44. abdullahalmamun et al. /journal of tropical forestry and environment vol. 5. no 01 (2015) 83-93 93 rahman, m.a., alam, m.s. and al-amin, m. 2006. segregation of biodegradable solid waste of chittagong metropolitan area based on specific physical and chemical properties. pakistan journal of biological sciences, 9(3): 460-464. reddell, p., yang, y. and shipton, w.a. 1997. do casuarina cunninghamiana seedlings dependent on symbiotic n2 fixation have higher phosphorus requirement than those supplied with adequate fertilizer nitrogen? plant and soil, 189: 213-219. ribet, j., and drevon, j.j. 1996. the phosphorus requirement of n2 fixing and urea-fed acacia mangium. new phytol, 132: 383-390. robson, a.d. 1983. mineral nutrition. in: broughton, w.j. (ed.), nitrogen fixation of legumes. oxford, uk: clarendon press, 3: 36-55. robson, a.d., o’hara, g.w. and abbott, l.k. 1981. involvement of phosphorus in nitrogen fixation by subterranean clover (trifolium subterraneum). australian journal of plant physiology, 8: 427-436. selivanovskaya, s.y. and latypova, v.z. 2006. effects of composted sewage sludge on microbial biomass, activity and pine seedlings in nursery forest. waste management, 26: 1253-1258. sinha, a.h.m. and enayetullah, m.i. 2000. community based solid waste management: the asian experience. dhaka, bangladesh: waste concern and usaid. sujauddin, m., huda, s.m.s. and hoque, a.t.m.r. 2007. household solid waste characteristics and management in. chittagong, bangladesh. waste management, 28: 1688-1695. vallini, g. and pera, a. 1989. green compost production from vegetable waste separately collected in metropolitan garden-produce market. biological wastes, 29(1): 33-41. world bank, 1999. what a waste: solid waste management in asia, washington dc, usa, p. 43. yang, y. 1995. the effects of phosphorus on nodule formation in the casuarina– frankia symbiosis. plant and soil, 176: 161-169. assessment of root plate structure in wind-thrown trees of melia dubia 50 assessment of root plate structure in wind-thrown trees of melia dubia a. n. arunkumar* and shakti chauhan institute of wood science and technology, bengaluru, india date received: 2018-03-27 date accepted: 2018-04-25 abstract root plays a significant role in tree growth and development and information pertaining to spread of the root and its depth will be useful for establishing plantations. most of the root studies are generally carried out in trees growing in urban areas in avenues, but limited studies are carried out in plantations. being an underground part of the tree, there are inherent difficulties in understanding root architecture. uprooting of trees due to storm or wind damage provides an ideal opportunity to obtain critical understanding about tree roots. such study has been carried out in an 11 year old storm ravaged melia dubia plantation in punjab, india. field observations such as tree girth, root girth, root plate width and depth was recorded on uprooted trees. a large variability was recorded for all the traits. root plate width and depth ranged from 1.42 to 5.17 m and 0.75 to 2.50 m, respectively. a strong positive relationship between tree girth and primary root girth, root plate width and depth identified in this study provides base line information which can be used while establishing m. dubia plantations. keywords: melia dubia, root plate, root width, root depth, wind-thrown 1. introduction tree roots are essential components which aid in supplying water, minerals, storage of carbohydrate, participate in hormonal signaling and most importantly providing physical anchorage in the soil (kozlowski and pallardy, 1997). therefore it plays a significant role in determining the size of the tree (thomas, 2000). studies on tree roots provide basic information to plantation managers about effect of spacing and thinning needed for raising trees. in agro-forestry, it provides an understanding on probable competition arising between tree roots and surface root feeding agricultural crops. however, tree root studies are generally difficult for tropical tree species and most of the studies are restricted to urban forestry (day, 2011). unlike agricultural crops, data on tree root studies are scanty because excavating roots is extremely difficult and enormously labour intensive. therefore root system analysis is not as easy as the above ground system (smith et al., 2011). moreover the periodic changes occurring in case of above ground morphological traits are well understood but not completely known in case of root system. limited studies that have been carried out on tree roots are those when trees are uprooted due to storm or wind damage. melia dubia (syn: m. composita) is an indigenous fast growing multipurpose tree attaining a height of 20 m, having a spreading crown with a cylindrical straight bole of about 9-10 m. in india, it is generally distributed in bengal, sikkim, upper assam, orissa, deccan and western ghats (parthiban et al., 2009). when converted in green state, the logs can be seasoned well. if left unseasoned for long, it tends to develop end splitting and discolouration. the wood has various uses such as packing cases, cigar boxes, ceiling planks, building and construction materials, agricultural implements, pencils, matchboxes, splints, catamarans, musical instruments, tea boxes, and plyboards (sharma, et al., 2012). *correspondence: anarunkumar@gmail.com issn 2235-9370 print/issn 2235-9362 online © university of sri jayewardenepura mailto:anarunkumar@gmail.com daham doi: 10.31357/jtfe.v8i1.3482 arunkumar & chauhan /journal of tropical forestry and environment vol. 8, no. 01 (2018)/ 50-54 51 further, the wood is extremely valued in veneer and can also be used for developing wood composites. m. dubia has been used in indian folklore medicine to control insect pests (kaul et al., 2002) and the bark extract of the tree has bio-pesticide properties (koul et al., 2002). it has also been integrated as an ideal tree species in agroforestry programmes (parthiban et al., 2009). 2. material and methods a melia dubia plantation (11-year-old) completely ravaged by a storm in the state of punjab provided us an opportunity to study its root structure. the plantation was established in 2001-02 at a spacing of 10x10 m in the palanpur beat (30.86 o n; 76.70 o e) having soil alluvial type in siswa range, ajitgarh division, shiwalik circle of punjab. the area experienced a heavy storm on the evening of 15th september 2013 lasting for over 30 minutes with the wind speed exceeding 70-80 km per hour. this left a trail of destruction (figure 1a). over 1,258 trees out of 2,400 trees in the plantation were completely uprooted. the study was carried out in december 2013, after ascertaining that there was no interference with this site. forty five uprooted trees were randomly selected for necessary data collection. tree girth (m) was measured at the collar region (30 cm above the soil and tree interface) and girth of the tap root/main root (referred as root girth) that descends from the trunk (m) was measured just below the root plate by clearing the soil mass adherent to the root. tree root plate is a stiff, shallow, horizontal disk-shaped rooting area, along with associated soil mass which is under and near the stem base (coder, 2014) (figure. 1b). the root plate depth (m) and width (m) was also recorded. root plate volume (m3) was estimated assuming the root plate as a spherical cap using the equation 1. a pearson’s correlation analysis was carried out to analyze the interrelationship between tree girth and root parameters figure 1a: wind thrown trees of melia dubia. figure 1b: a typical root plate structure of melia dubia. 52 (1) where; v= root plate volume h=root plate depth r=root plate radius 3. results and discussion a large variability in all the parameters is evident from table 1 as the coefficient of variation value is more than 25% for all parameters and the highest being in root girth (45.08%). tree girth ranged from 0.58 to 1.80 m, where as the root girth varied from 0.18 to 1.37 m. root plate width and depth ranged from 1.42 to 5.17 m and 0.75 to 2.50 m, respectively. it is interesting to note that tree girth was nearly twice the size of primary root girth. similarly, root plate width was nearly twice that of root plate depth. the relationship of root plate parameters with tree girth, the single most important above ground morphological trait was also investigated (table 2). table 1: descriptive statistics for tree girth, root girth, root plate width and depth. s. no. parameter mean cv (%) minimum maximum 1 tree girth (m) 1.08 27.64 0.58 1.80 2 root girth (m) 0.52 45.08 0.18 1.37 3 root plate width (m) 3.20 31.09 1.42 5.17 4 root plate depth (m) 1.55 23.65 0.75 2.50 5 root plate volume (m3) 9.75 71.22 1.51 27.19 table 2: correlation matrix between tree girth and root parameters. tree girth root girth root plate width root plate depth tree girth 1 root girth 0.57* 1 root plate width 0.71* 0.32 1 root plate depth 0.72* 0.48* 0.64* 1 root plate volume 0.77* 0.42* 0.92* 0.83* (* p<0.01) tree girth had a strong positive relationship with primary root girth (r=0.57, p<0.01), root plate width (r=0.71, p<0.01) and depth (r=0.77, p<0.01) and root volume (r=0.77, p<0.01). in a study carried out on alnus incana, the stem diameter at breast height was strongly correlated with root biomass fractions (bardulius et al., 2015). trees stand tall and upright with extremely variable wind and soil conditions. the above ground and underground portions in a way seems to be different parts as one is visible and other is hidden, they work in tandem such that biomechanical optimization is at its best (coder, 2014). although the main root girth showed significant positive relationship with root plate width and depth, the strength of association was moderate. root plate width also exhibited a positive association with root depth. root girth provides an estimation of the root longevity, bending stiffness and the capacity of soil penetration. several factors play a strong role in tree root formation, development and spread. these include the site, climate, silvicultural practice, biology, soil, geology, hydrology apart from the arunkumar & chauhan /journal of tropical forestry and environment vol. 8, no. 01 (2018)/ 50-54 53 species itself. generally, root depth in trees varies from one to three meters (crow, 2005) and in m. dubia it was found that the average root plate depth is 1.55 m. however, it should be emphasised that out of 45 trees, only four trees had a root depth of more than 2 m. jha (2017) reported that hybrid poplar a fast growing tree species when grown in forest system and agroforestry system the root depth was 2.4 and 2.8 m, respectively which is higher than observed in this study. being a fast growing tree species and grown in fertile alluvium derived soils (sandy to sandy loam) where the soil water availability is in abundance, it is quite likely that roots might have not penetrated deep. generally it is overstated that tree roots penetrate deeper into the soil. due to varied sites and species, in case of shallow soils, the root depth is generally underestimated and extensive studies are essential (van noordwijk et al., 2015). 4. conclusion the vulnerability of higher girth trees of m. dubia to heavy wind or storm should be considered as a caution by the tree growers in the areas prone to such events. relationship between tree girth and root parameters had not been reported earlier for any plantation grown mature tropical tree species in india. therefore, further studies on understanding the influence of soil types on fast growing tree species cultivated in different agroclimatic zones is essential before arriving at suitable management practices. acknowledgement authors are thankful to the director, institute of wood science and technology, bengaluru, india for his support. we thank the division forest officer and staff of sahibzada ajit singh nagar forest division, department of forests and wildlife preservation, punjab for their assistance. we express our gratitude to professor h. y. mohan ram, insa srinivasa ramanujam research professor, for his critical suggestions during the manuscript preparation. references bardulis, a., lazdiņa, d., daugaviete, m., bardule, a., daugavietis, u., rozitis, g., 2015. above ground and below ground biomass in grey alder alnus incana (l.) moench. young stands on agricultural land in central part of latvia. agronomy research. 13: 277–286. coder, k. d., 2014. tree anchorage and root strength. university of georgia warnell school of forestry and natural resources monograph publication, pp.67. crow, p. 2005. the influence of soils and species on tree root depth. information note fcino78 forestry commission edinburgh. day, s., 2011. tree root ecology in the urban environment and implications for a sustainable rhizosphere. arboriculture and urban forestry. 36: 149–159. jha, k.k., 2017. root structure and belowground biomass of hybrid poplar in forestry and agroforestry systems in mediterranean france. not. sci. biol. 9:422-432. kaul, o., multani, j.s., singh, g., wahab, s. 2002. bioefficacy of toosendanin from melia dubia against gram pod-borer, helicoverpa armigera (hubner). current science. 83:1387-1391. koul, o., jain, m.p., sharma, v.k., 2000. growth inhibitory and antifeedant activity of extracts from melia dubia to spodptera litura and helicoverpa armigera larvae. indian journal of experimental biology. 38:36-38. kozlowski, t,, pallardy, s., 1997. physiology of woody plants. academic press, usa. parthiban, k.t., bharathi, a.k., seenivasan, r., kamala, k., rao, m.g.2009. integrating melia dubia in agro-forestry farms as an alternate pulpwood species. asia pacific agroforestry newsletter. 34: 3-4. 54 sharma, s.k., shukla, s.r., sujatha, m., shashikala, s., kumar, p. 2012. assessment of certain wood quality parameters of selected genotypes of melia dubia cav. grown in a seedling seed orchard. journal of indian academy of wood science. 9: 165-169. smit, a.l., bengough, a.g., engels, c., van noordwijk, m., pellerin, s., van de geijn, s.c., 2000. root methods: a handbook. springer, berlin. thomas, p., 2000. trees: their natural history. cambridge university press, uk. van noordwijk, m., lawson, g., hairiah, k., wilson, j., 2015. root distribution of trees and crops: competition and/or complementarity. in: ong, c. k., colin, b. r., wilson, j., (eds.) tree-crop interactions: agroforestry in a changing climate. wallingford, uk, cab international, 221257. crow, p. 2005. the influence of soils and species on tree root depth. information note fcino78 forestry commission edinburgh. microsoft word 1 subasinghe feature subasinghe /journal of tropical forestry and environment vol. 3, no. 01 (2013) 1-8 1 feature article sandalwood research: a global perspective s.m.c.u.p. subasinghe department of forestry and environmental science, university of sri jayewardenepura, nugegoda, sri lanka 1. introduction sandalwood is a commercially and culturally important plant species belonging to the family santalaceae and the genus santalum. sandalwood oil extracted from the heartwood has been used for perfumery, medicinal, religious and cultural purposes over centuries of years. in addition to oil, the wood and its powder are used for religious, cultural and medicinal purposes especially in the asian and arab regions. there are around 18 sandalwood species belonging to the genus santalum which are; s. freycinetianum, s. haleakalae, s. ellipticum, s. peniculatum, s. pyrularium, s. involutum, s. boninese, s. insulare, s. austrocaledonicum, s. yasi, s. macgregorii, s. accuminatum, s. murrayanum, s. obtusifolium, s. lanceolatum, s. fernandezianum, s. salicifolium and s. spicatum. all the sandalwood species are identified as obligate wood hemi-parasites which means they absorb certain nutrients such as phosphates and nitrates from the host trees via root connections called haustoria. the global distribution of the sandal family is between 30 degrees n and 40 degrees s from indonesia in west to juan fernandez island in the north to new zealand in the south. these species are mainly found in india, indonesia, australia, timor, hawaii etc. out of the 18 species mentioned above, about 6 species can be found in hawaii islands which shows the highest sandalwood diversity. the main reason for the economic and cultural value of sandalwood is the oil contained in the sandalwood timber, mainly in the heartwood. heartwood oil content varies, however, widely between species and even within species. s. album known as indian sandalwood is renowned for its oil, which is highly rated for its sweet, fragrant, persistent aroma and the fixative property which is highly demanded by the perfume industry. jain et al (2003) reported that heartwood of s. album was priced at 12 lakhs of indian rupees per tonne and oil was priced at 22,000 indian rupees per kg. however, the prices are highly depended on the quality. due to the high value of oil and timber, s. album has been central among all sandalwood species in the aspect of research. currently most of the world demand of sandalwood is supplied from australia using s. spicatum known as australian sandalwood. due to the high value and the demand, there is a growing attention at present in establishing sandalwood, especially s. album plantations in the tropical region including sri lanka over the most demanding other forest plantation species, i.e., teak, mahogany etc. by the private sector plantation companies, due to the large domestic demand and the existing high demand. in accordance with that, there is a trend in sandalwood plantation establishment in australia, india, sri lanka, china, and fiji since recently. however, the plantation sector lacks the information on establishing sandalwood plantations, which is identified as a great risk when considering their profit maximising goal. without the information such as nursery techniques, host suitability, plantation establishment, growth rates and oil characteristics, managers of sandalwood plantations might therefore face difficulties in achieving the expected outcomes. *correspondence: upuls@sjp.ac.lk tel: +94-112758421, fax: +94 112803470 issn 2235-9370 print / issn 2235-9362 online ©2013 university of sri jayewardenepura subasinghe /journal of tropical forestry and environment vol. 3, no. 01 (2013) 1-8 2 2. sandalwood research at global perspective scientific research on sandalwood started in the period of 1940-50. it was commenced with the silvicultural trials because that was the time the sandalwood, especially s. album was started to introduce to countries like australia from its native range of existence. from that era, research evolves from silvicultural studies, ecological studies to oil chemistry and genetics. most of such researches were funded by the different research institutes and different governments due to the importance of having new information on these species. however, according to the reputed sandalwood research devotees, still there are areas to be further explored in sandalwood research. the following sections analyse the researches conducted on different areas of sandalwood in the past. 2.1. ecological studies most of the ecological distribution and population studies have been conducted for the sandalwood species growing in the australian and pacific regions of the world. the reason may be due to the interest of the scientists living in the same regions and usa. the other reason of having many studies completed in the pacific region could be the presence of the threatened or very rare sandalwood species in that particular region, especially in hawaii islands. comparatively a little amount of ecology and distribution research has been done on s. album, commercially the most important species of all sandalwoods which is naturally growing in india, si lanka and indonesia. some of the sandalwood ecology and population studies were conducted on regional basis such as the study of sinha (1991) on sandalwood in bundelkhand forest division, uttar pradesh of india, s. album profile study conducted in pondicherry region of india by balachandran and kichenamourthy (2007), the dendrological research on s. paniculatum in the dry montane forests of mauna loa of hawaii island conducted by senock (2012), and sandalwood resources and its management in east nusa tenggara, timor province of indonesia by septiani (2012). a large amount of ecological research of sandalwood species have been conducted in more broader manner, e.g., distribution and ecology of s. insulare by butaud (2004); distribution and status of sandalwood in hawaii by stemmermann (1990). the distribution and ecology research were not conducted on s. album in sri lanka which is an important area to study because of the recent finding of growing this species beyond the mid-country intermediate zone where known to produce good quality sandalwood. 2.2. silviculture and propagation silviculture research of sandalwood perhaps has the longest history among all types of sandalwood research conducted in the past. s. album was frequently studied in this aspect mainly because this species was tried to introduce to many new locations or countries as its oil has the highest value among all sandalwood species. seed germination was given a priority among the silvicutlure studies by many researchers around the world, e.g., doran (2012) annupurna et al (2006), gamage et al (2010), nagini and shrimathi (1985). the reason of this was due to the prolonging dormancy period and low germination rates of sandalwood seeds. prof. j.e.d. fox was one of the pioneers to study the silviculture and host species of s. album in the world (fox, 2000; brand et al, 1993; struthers, 1986). following his work, many researches were conducted in the recent past on the effect of different host species in different localities, e.g., ananthapathmanabha (2012), subasinghe and hettiarachchi (unpublished), nagaveni and vijayalakshmi (2003). those studies conducted on s. album showed a variation of results. however, the most commonly identified suitable hosts by the above mentioned researches were pongamina pinnata, casuarina equestifolia and sesbenia grandiflora. in 2004, brand et al conducted a study on the effect of acacia host species on s. spicatum growing in australia and they found out a. saligna and a. acuminate as the best species. however, those studies should be further researched to find out the most suitable species for different climatic regions. subasinghe /journal of tropical forestry and environment vol. 3, no. 01 (2013) 1-8 3 there was an interest among the researchers especially in the pacific region from the past to form hybrids of sandalwood. these studies mainly focused on producing higher contents of sandalwood oils with a better survival rate. according to ananthapathmanabha (2012), s. album x s. yasi hybrid called f1 shows a more vigour and an average of 7% oil which is almost impossible to obtain from the parent trees. in 1998 mccomb and jones attempted to form a hybrid using s. album and s. spicatum using in vitro culture method. a trial established in hawaiian ethnobotanical garden of honolulu in 1959 in hybridisation of s. frecinetianum and s. album is still present. however, there is a debate on the quality of the oil produced by those hybrids and further, there is a fear among the top level sandalwood merchants in entering low quality sandalwood oils by the hybrid species to the market. biotechnological approaches were also attempted to propagate s. album in mass scale by many scientists. bapat and rao (1998) and sanjaya et al (1998) conducted detailed studies on that aspect in india. 2.3. pests and diseases of sandalwood the pests and diseases of sandalwood were mainly studied by indian scientists on s. album. sundararaj and muthukrishnan (2011), sundararaj (2012) identified 92 sap-suckers, 60 defoliators, 6 stem borers, 5 bark and dead wood feeders, 3 dry wood feeders, 3 seed feeders and 1 flower feeder on s. album growing in india. however, among those pests, only a few are harmful. in addition, remadevi (2012) has conducted research on the bio-deterioration of sandalwood logs by termites. bio-deterioration severely lowers the log quality. especially for the ones that are used for carvings. she further found that, the light traps can effectively be used against those termites. in addition, a phytoplasma like disease named spike disease has also been identified at the nursery stage of s. album (gowda and narayana 1998; rangaswami, 1998). however, a limited number of studies have been conducted on the other sandalwood species on pests and diseases. 2.4. variations of sandalwood oil contents the values of the oils are ranked in the world market of sandalwood as shown in the table 1. the rest of the species produce low or no value in the oils or the other oil producing sandalwood species such as s. haleakalae became very rare. table 1: commercially valuable sandalwood species and their natural distribution rank scientific name vernacular name natural distribution 1 2 3 4 5 6 s. album s. yasi s. asutrocaledonicum s. macgregorii s. spicatum s. lanceolatum indian sandalwood vanuatu sandalwood austrian sandalwood northern sandalwood india, indonesia, sri lanka fiji, niue, tonga new caledonia, vanuatu papua new guinea, indonesia australia australia the most important concern among the sandalwood growers is therefore the oil quantity that can be obtained from a harvested tree. this amount usually expressed as a weight percentage to the amount of sandalwood timber used to extract the oil. most studies have been conducted on s. album in this regard in the past because it produces the most important oil among all sandalwood species. the study conducted by doran et al (2005) on young s. yasi and s. album growing in the pacific region showed a low amount of oil in both species due to low formation of heartwood at the early years. however, the f1 hybrid formed by s. yasi x s. album showed a high vigour and thereby comparatively a high amount of oil content. xiaojin et al (2011) found out the variation of oil content of 6 year old s. album growing in gaoyao, guangdong province, south china from 0.64% to 1.78%. subasinghe /journal of tropical forestry and environment vol. 3, no. 01 (2013) 1-8 4 the studies conducted in sri lanka by subasinghe et al (2013) on s. album in sri lanka showed a higher variation of oil content. they, however, found significantly high oil content, i.e., 6.36% in some trees tested. it is encouraging for the sandalwood growers in sri lanka to find the sandalwood trees with high oil contents. this study is conducted further in larger extents to identify more variations and the reasons under the funding of the national research council of sri lanka (subasinghe and hettiarachchi, unpublished). in addition to those studies, many other researchers, e.g., doran et al (2005), joulain et al (2012), jain et al. (2003) found a high variation of oil between individuals of similar size and growing in the same area. these variations were, however, not properly explained by the authors and therefore it can be suspected that the genetic factors may play a significant role in oil formation. in addition it may also be due to the climatic and topographical factors. 2.5. chemistry of sandalwood oil sandalwood oil known as santalol is the most important part of the sandalwood tree. it contains a larger number of chemical compounds. however, the specific aroma of sandalwood oil is produced mainly by two chemical compounds known as alpha and beta santalols. therefore in order to maintain the oil quality, iso standards have been formulated by iso 3518:2002 for s. album and s. spicatum as given in the table 2 for those two compounds. the rest of the commercially valuable sandalwood species should follow the levels of s. album. table 2: iso standards given for alpha and beta santalol levels species iso standard alpha % beta % s. album s. spicatum 41.0-55.0 15.0-25.0 41.0-55.0 5.0-20.0 in accordance with the figure given in the table 2, many researches have been conducted on the quality of oil and its variations between the individuals of the same species, between species, locations, tree size and oil extraction method etc. however, according to the results conducted in oil content variations the past, it was evidenced that the oils of the different sandalwood species may not always in the region of the expected santalol levels. the research conducted especially on s. album, s. spicatum, a. yasi, s. austrocaledonicum etc. by hettiarachchi (2008), moniodius (2012), day (2012), brand et al., (2006), xiaojin et al., (2011) indicate wide range of alpha and beta santalol levels over the expected ranges due to unknown or unidentified causes. in addition, researches have been conducted on farnesol levels of sandalwood oils mainly because it has been identified as an allergy causing substance of the sensitive skins (hettiarachchi 2008, joulian 2012, subasinghe et al., 2013). the unknown causes of the variation of sandalwood oil compounds show the importance of conducting further research on sandalwood oil formation and the external and internal parameters that may affect its quality. however, there may be a strong influence of genetic characteristics to the quality parameters of sandalwood oil as suspected by subasinghe and hettiarachchi (unpublished) because they noticed unexplainable oil quality variations of s. album trees of similar size growing under very similar soil and climatic conditions. 2.6. genetics sandalwood genetics studies became more popular in the near past with the acceleration of such research by australian and american scientists. dna bar-coding has been done for many species and frequent uses of micro-satellites were common in those researches. harbaugh (2008) used these methods for differentiating sandalwood species and individuals and according the results, she formed a theory on the origin of all sandalwood species in australia. dna cloning has also been done for protein compounds subasinghe /journal of tropical forestry and environment vol. 3, no. 01 (2013) 1-8 5 by sita and bhattacharya in 1997 for s. album. in 1998, jain et al also studied on genetic variations of s. album provenances of india. genetic mapping of indian sandalwood resources were done by nageshwararao in 2012. jones et al (2006, 2008, 2011) conducted detailed genetic studies on s. album in australia. their studies were mainly focused on dna isolation and fragrance biosynthesis of s. album. 3. conservation status of sandalwood species sandalwood is recognised worldwide as one of the most valuable commercial tree species. due to the over harvesting from the wild and lack of sufficient plantation establishment, sandalwood resource declined worldwide from the past in rapid manner. for example, recent data on production of sandalwood in india show a declining trend. india’s sandalwood production dropped from 4,000 mt heartwood per year in the 1950s to a mere 500 mt in 2007 as against the global annual demand of about 5,000 to 6,000 mt wood and around 100 to 120 mt oil (dhanya et al, 2010). in addition to that, grazing and land conversion to agriculture crops such as sugar cane and pine apple have caused the sandalwood resource decline especially in australia and hawaii. according to harbaugh (2008), one sandalwood species has already been extinct due to over harvesting and many of others like s. haleakele are in highly threatened situation. due to the facts mentioned above, the governments like australia, hawaii, india, new caledonia, and sri lanka have taken actions against illegal harvesting and formulated rigid policies in conservation of the sandalwood resources. joining with the governments, different organizations such as international sandalwood foundation operated from united states, iliahi foundation of sandalwood of hawaii promote research and take actions in conservation of sandalwood species in the world. india has realised the value of sandalwood trade and at the same time, to protect the wild grown sandalwood resources, karnataka and tamil nadu provinces of india changed the existing policies to promote sandalwood growing in private lands. realising the flaws in sandal policy which endangered the species, government of karnataka came up with amendment to karnataka forest act in 2001 to encourage private domestication of sandalwood as means to conserve and enhance the status of this resource (dhanya et al, 2010). the amendment gave landowners legal right to trees on their land and made them eligible to receive full value on extraction. shortly, tamil nadu followed the same path and with the tamil nadu forest (amendment) act of 1998 in 2002, the landowners were given the right to trees (dhanya et al, 2010). 4. final remarks research has been conducted on various species of sandalwood on many aspects such as ecology, silviculture, plantation establishment, pests and disease, genetics etc. in different parts of the world. however, the rate of plantation establishment has still not promising in sandalwood growing countries other than for s. album cultivation in australia. therefore the information generated by different researchers should come to a central point so that everybody can use them in plantation establishment and conservation. in addition, more research are needed in developing methods to identify the genuine sandalwood oils from the fake products as the present market is flooded with such low quality artificial oils deliberately manufactured to capture the sandalwood market. in addition, more research should be conducted on the oil quality of hybrid sandalwood varieties although some hybrids such as s. album x s. yasi show promising improvements in vigour and oil contents. the reasons for the sandalwood oil content variation are still not properly known and therefore it is vital to identify the high oil producing trees especially s. album which is intensively used for sandalwood plantation establishment in australia, china and sri lanka. such high oil yielding trees can be used as mother trees or parents so that the next generations can be formed by using them. subasinghe /journal of tropical forestry and environment vol. 3, no. 01 (2013) 1-8 6 in addition to that, it is the time that the scientists of different disciplines should work together to achieve the better outcomes of sandalwood research and therefore this paper proposed to enhance the collaborative research work between different universities of different countries so that the better outputs can be achieved. references ananthapadmanabha, h.s. 2012. indian sandalwood market trend production. proceedings of international sandalwood symposium, 21-24 october, 2012, honolulu, hawaii annupurna, d. rathore, t.s., joshi, g. 2006. modern nursery practices in the production of quality seedlings of indian sandalwood. journal of sustainable forestry 22:33-35 balachandran, n., kichenamourthy, s. 2007. profile of natural stands of santalum album l. in the pondicherry region, india. sandalwood research newsletter 22:4-9 bapat, v.a., rao, p.s. 1998. biotechnological approaches for propagation of sandal (santalum album l.). (in) sandal and its products, a.m. radomiljac, h.s. ananthapadmanabha, rm. welbourn and k. salyanarayana rao (eds), australian centre for international agricultural research canberra, 42-44 brand, j.e., fox, j.e.d, effendi, m. 1993. variation in seed size and germination of santalum album l. populations in ntts timor. santalum 12:37–49 brand j.e., jones, p., donovan, o. 2004. current growth rates and predicted yields of sandalwood (santalum spicatum) grown in plantation in south-western australia. sandalwood research newsletter 19:4-7 brand, j.e., kimber, p., streatfield, j. 2006. preliminary analysis of indian sandalwood (santalum album l.) oil from a 14-year-old plantation at kununurra, western australia sandalwood research newsletter 21:1-3 butaud, j.f. 2004. santalum insulare (bertero ex a. dc.): distribution and ecology. sandalwood research newsletter 19:1-4 day, j. 2012. musings of sandalwood oil distiller. proceedings of international sandalwood symposium, 21-24 october, 2012, honolulu, hawaii dhanya, b., viswanath, s., purushothman, s. 2010. sandal (santalum album l.) conservation in southern india: a review of policies and their impacts journal of tropical agriculture 48(1–2):1–10, 2010 doran, j. 2012. review of santalum album seed pre-germination treatments with a focus on low cost methods. proceedings of international sandalwood symposium, 21-24 october, 2012, honolulu, hawaii doran, j.c., thomson, l., brophy, j.j., goldsack, b., bulai, p., faka'osi, t., mokoia, t. 2005. variation in heartwood oil composition of young sandalwood trees in the south pacific (santalum yasi, s. album and f1 hybrids in fiji, and s. yasi in tonga and niue). sandalwood research newsletter 20:3-7 fox, j.e.d., 2000. sandalwood: the royal tree. biologist, 47:31. gamage, y.m.m., subasinghe, s.m.c.u.p., hettiarachchi, d.s., change of seed germination rate with storage time of santalum album l. (indian sandalwood) seeds. proceedings of the 15th international annual forestry and environment symposium, 26-27 november, 2007, university of sri jayewardenepura, sri lanka gowda, a.n.s., narayana, r., 1998. in-vitro comparative morphogenetic studies of normal and spikediseased tissues of sandal (santalum album l.). (in) sandal and its products, a.m. radomiljac, h.s. ananthapadmanabha, rm. welbourn and k. salyanarayana rao (eds), australian centre for international agricultural research canberra, 167-174 harbaugh, d. 2006. molecular and morphological phylogeny of sandalwoods: insights for biogeography and taxonomy. sandalwood research newsletter 21:8. hettiarachchi, d.s. 2008. volatile oil content determination in the australian sandalwood industry: towards a standardised method. sandalwood research newsletter 23:1-4. subasinghe /journal of tropical forestry and environment vol. 3, no. 01 (2013) 1-8 7 jain, s.h., angandi, v.g., shankaranarayana, k.h., rajeevalochan, a.n., theagarajan, k.s., ragaswami, c.r. 1998. identification of provenances of sandal in india for genetic conservation. (in) sandal and its products, a.m. radomiljac, h.s. ananthapadmanabha, rm. welbourn and k. salyanarayana rao (eds), australian centre for international agricultural research canberra, 117-120 jain, s.h., angandi, v.g., shankaranarayana, k.h., ravikumar, g. 2003. relationship between girth and percentage of oil in sandal provenances. sandalwood research newsletter 18:4-5 jones, c.g., ghisalberti, e.l., plummer, j.a., barbour, e.l. 2006. quantitative cooccurance of sesquiterpenes: a tool for elucidating their biosynthesis in indian sandalwood, santalum album. phytochemistry, 67(22):2463−2468. jones, c.g., keeling, c.i., ghisalberti, e.l., barbour, e.l., plummer, j.a., bohlmann, j. 2008. isolation of cdnas and functional characterisation of two multiproduct terpene synthase enzymes from sandalwood, santalum album l. archives of biochemistry and biophysics, 477(1):121−30. jones, c.g., moniodis, j., zulak, k.g., scaffidi, a., plummer, j.a., ghisalberti, e.l., barbour, e.l., bohlmann, j. 2011. sandalwood fragrance biosynthesis involves sesquiterpene synthases of both the terpene synthase (tps)-a and tps-b subfamilies, including santalene synthases. the journal of biological chemistry, 286 (20):17445-17454. joulain, d., nengone, s.n., de guahma, d., dit lyo, l. 2012. new insights into the qualitative and quantitative analytical chemistry of sandalwood essential oils new caledonia, france. proceedings of international sandalwood symposium, 21-24 october, 2012, honolulu, hawaii mccomb, j.a., jones, m.g.k. 1998. interspecific hybridisation between santalum album and s. spicatum. (in) sandal and its products, a.m. radomiljac, h.s. ananthapadmanabha, rm. welbourn and k. salyanarayana rao (eds), australian centre for international agricultural research canberra, 36-41 moniodius, j. 2012. chemical diversity and biosynthesis of australian sandalwoods’ essential oil. proceedings of international sandalwood symposium, 21-24 october, 2012, honolulu, hawaii nagaveni, h.c., vijayalakshmi, g. 2003. growth performance of sandal (santalum album l.) with different host species. sandalwood research newsletter 18, 1-4. nageswara-rao, m. 2012. mapping sandal genetic resources in india: threats and conservation strategies. proceedings of international sandalwood symposium, 21-24 october, 2012, honolulu, hawaii nagini, h.c., shrimathi, a.r., 1985. germination capacity of floating & inking sandal seeds. indian forester 111(8):615-618. rangaswami, k.t. 1998. fluorescence microscopy of sandal affected with spike disease (in) sandal and its products, a.m. radomiljac, h.s. ananthapadmanabha, rm. welbourn and k. salyanarayana rao (eds), australian centre for international agricultural research canberra, 181 remadevi, o.k. 2012. sandalwood biodeterioration in indian conditions: causes, impacts and remedies. proceedings of international sandalwood symposium, 21-24 october, 2012, honolulu, hawaii sanjaya, ananthapadmanabha, h.s., rai, v.r. 1998. in-vitro shoot multiplication from the mature tree of santalum album l. (in) sandal and its products, a.m. radomiljac, h.s. ananthapadmanabha, rm. welbourn and k. salyanarayana rao (eds), australian centre for international agricultural research canberra, 45-49 senock, r.s. 2012. status of dendrological research on santalum paniculatum in the dry montane forests of mauna loa in hawaii island. proceedings of international sandalwood symposium, 21-24 october, 2012, honolulu, hawaii septiani, y. 2012. sandalwood resources and its management in east nusa tenggara timor province, indonesia. proceedings of international sandalwood symposium, 21-24 october, 2012, honolulu, hawaii sinha, r.l. 1991. sandalwood in bundelkh and forest division, uttar pradesh. indian forester 87(10):590-597 sita, g.l.a., bhattacharya, a. 1998. cdna cloning and characterisation of a proline(or hydroxyproline) rich protein from santalum album l. (in) sandal and its products, a.m. radomiljac, h.s. subasinghe /journal of tropical forestry and environment vol. 3, no. 01 (2013) 1-8 8 ananthapadmanabha, rm. welbourn and k. salyanarayana rao (eds), australian centre for international agricultural research canberra, 29-35 stemmermann, l. 1990. distribution and status of sandalwood in hawaii. proceedings of the symposium on sandalwood in the pacific 9-11 april, 1990, honolulu, hawaii struthers, r., lamont, b.b., fox, j.e.d., wijesuriya, s., crossland, t. 1986. mineral nutrition of sandalwood (santalum spicatum) journal of experimental botany 37(9):1274-1284 subasinghe, s.m.c.u.p., hettiarachchi, d.s. unpublished. establishment of indian sandalwood (santalum album) plantations and determination of the variation of oil contents in different geographical regions of sri lanka, national research council, sri lanka. subasinghe, u., gamage, m., hettiarachchi, d.s. 2013. essential oil content and composition of indian sandalwood (santalum album) in sri lanka. journal of forestry research 24(1): 127-130 sundararaj, r. 2012. insect pest complexes of indian sandalwood in areas outside forest and the challenges in its management. proceedings of international sandalwood symposium, 21-24 october, 2012, honolulu, hawaii sundararaj, r., muthukrishnan, r. 2011. population dynamics of some coccids (coccoidea: hemiptera) infesting sandal (santalum album linn.) in bangalore, india. journal of forestry research 22(2):259262 xiaojin, l., daping, x., zengjiang, y., ningnan, z., lijun, y. 2011. preliminary analysis of growth and oil composition from a 6-year-old sandal (santalum album l.) plantation in gaoyao, guangdong, south china. sandalwood research newsletter 26:1-5 chapter five: discussion 76 leaf extracts of lobelia nicotianaefolia as a potential biopesticide against defoliator pests b. deepa 1* and o.k. remadevi 2 1 forest and wood protection division, institute of wood science and technology, bengaluru, india 2 environmental management and policy research institute (empri), doresanipalya forest campus, bengaluru, india date received: 10-11-2015 date accepted: 30-11-2015 abstract the environmental concern and global demand for organically produced products provide an impetus to search for new, effective, safe and economical pesticidal formulations. plants provide enormous scope for development into pesticides. though more than 2000 plants are known to possess insecticidal properties, neem is the only established botanical pesticide. hence in this study, we tested the insecticidal activities of the organic solvent extracts from the leaves of l. nicotianaefolia against the larval and egg stages of a serious defoliator pest, hyblaea puera as the test insect. the organic solvent extracts of the leaf of l. nicotianaefolia were evaluated for their contact and feeding toxicity. the larvicidal action by contact toxicity on 3 rd instar larvae of h. puera showed 100% mortality at 25% concentration. the ovicidal activity varied among the different extracts. all the treatments did not show any activity and were on par with control except ethyl acetate and water extracts and exhibited highest egg hatch inhibition (80%) and (64%) respectively at highest concentration (2%). the lc50 value for ethyl acetate extract and water extract was 0.55 and 1.014 respectively was not significant (p>0.05) for ovicidal action. the feeding toxicity tests performed on 4 th instar larvae of h. puera showed that among all the extracts of l. nicotianaefolia, methanol extract showed highly significant insecticidal activity with mortality of 92%, followed by ethyl alcohol extract (90%) and water extract (86%). the study reveals that l. nicotianafolia has immense potential to be explored as botanical pesticide. keywords: lobelia nicotianaefolia, hyblaea puera, larvicidal, ovicidal, botanical pesticide 1. introduction lobelia nicotianaefolia roth ex roem. & schult. is commonly known as indian tobacco, wild tobacco, asthma weed, vomit root, gag root, pulse weed, emetic herb and bladder pod. in india, it is distributed along the western ghats and is also found in deccan and konkan at altitudes of 900-2,100 m. l. nicotianaefolia is an annual shrub which grows to a height of upto 1.2-3.6 m. leaves and flowering tops of the plant is a rich source of alkaloids of the lobeline group. the whole plant, when dry, develops small spots of resinous exudation, which is hot and acrid. leaves and aerial parts of the plant exude white latex which causes dermatitis. seeds contain a narcotic poison and are commonly used for insect and scorpion bites. according to nayar et al. (1979) the leaf infusion of l. excelsa is * correspondence: deepa_balan2002@rediffmail.com tel: +91 9448803195 issn 2235-9370 print/issn 2235-9362 online © university of sri jayewardenepura deepa & remadevi /journal of tropical forestry and environment vol. 5. no 02 (2015) 76-82 77 effective against aphids on snakegourd and cowpea, tingid bugs on brinjal and mites on castor and lady’s finger. jayadevi et al. (2003) studied the effect of cold and hot water extracts of l. nicotianaefolia leaf against, plutella xylostella. ovicidal properties of the hot water extract of the leaves of l. nicotianaefolia were studied by javaregowda and krishna naik (2007). in this study, we tested the insecticidal activities of the organic solvent extracts from the leaves of l. nicotianaefolia against the larval and egg stages of a serious defoliator pest, hyblaea puera as the test insect. 2. methodology the test insect, h. puera cramer (lepidoptera: hyblaeidae) is the most important defoliator pest of teak in india, causing serious damage to teak trees. h. puera infestations usually occur in teak plantations almost every year mainly during the early flushing period of teak. various teak plantations in and around karnataka (devanahally, gottipura, nellal, nagarahole range of rajiv gandhi national park, yelwal, gundiya, shibaje) and kerala (nilambur) in india were visited during the course of study to collect the pupae of h. puera. the insect culture was maintained following the methodology of nair et al. (1998). the pupae were brought to the laboratory and maintained in glass bottles covered with muslin cloth. the emerging adults were kept in cages overnight and then kept as pairs in separate glass bottles for mating. they were provided with 10% honey solution for feeding. the adults usually mated on the first or second day of emergence and started laying eggs from the third night onwards. the eggs were laid on the cloth covering the bottles. the eggs were washed in 0.5% sodium hypochlorite solution for 10 minutes. after air-drying, the eggs were kept for emergence in glass bottles along with freshly collected tender teak leaves, sprayed with 0.5% sodium hypochlorite and air-dried. the larvae were kept in glass bottles along with fresh leaves and covered with muslin cloth. in each glass bottle 20-40 larvae were kept depending upon the instar. on moulting, larvae were changed to fresh bottles. on pupation, the pupae were removed and transferred to sterilised glass bottles. insect culture was maintained in the laboratory at 28º c and 16 l: 8d photoperiod and at 85% humidity. to maintain hygienic conditions the entire culture area was often sterilized with 70% alcohol. the glassware’s were sterilized with formalin after each wash. 2.1 preparation of crude extract the leaf samples of l. nicotianaefolia were collected from karnataka (shampaje and madikere forests and in and around ponnampet) in india. the leaves were cleaned and shade dried. the dried plant material was powdered in a mixer. 100 g of the plant material was dissolved in 250 ml of each of the solvent namely petroleum ether, chloroform, methanol, ethyl alcohol, ethyl acetate, acetone and water and kept for 48 hours in sealed round bottom flasks. after 48 hours, it was extracted in soxhlet apparatus until the eluting solvent turned colour less. the solvent was evaporated using rotary evaporator and the dry crude extract obtained was weighed and stored in refrigerator. 2.2 preparation of the test concentrations a known amount of crude extract obtained from the above process was dissolved in respective solvent in 1:1 proportion and serially diluted with water to obtain the desired concentrations of 0.25%, 0.5%, 1%, 2% and 4%. one drop of emulsifier (0.005%) (tween 20, sigma chemical company) was added to the extract to ensure complete dispersion of the active ingredient. 2.3 contact toxicity with crude extract to evaluate the contact toxicity effects of crude extracts of l. nicotianaefolia leaf, two bioassays namely, larvicidal action and ovicidal action were conducted. 78 2.4 larvicidal action with crude extract for bioassays to evaluate larvicidal action of crude extracts early 3 rd instar larvae of h. puera of uniform age and weight range (9-13 mg) obtained from laboratory culture were used. contact toxicity was tested with 0.25%, 0.5%, 1%, 2% and 4% concentrations. five replications with 10 individuals each were used for each concentration. larvae were introduced into sterilised plastic petri plates. the test solutions were applied on larvae, as topical spray using a tlc (thin layer chromatography) sprayer. the petri plates were covered with the lid. in blank group the larvae were sprayed with water and in the control group the larvae were sprayed with respective solvent. the group of larvae treated with the emulsifier tween 20 also served as control. observations were made on the behaviour of the larvae and mortality was observed at hourly intervals. 2.5 ovicidal action 12-hour-old eggs were carefully taken on a small piece of muslin cloth using fine camel hair brush. five replications with 5 eggs each were used for the experiment. the extract was prepared at a concentration of 2%, 1% and 0.5%. it was sprayed on the egg using a micropipette. the cloth with the eggs after complete drying was introduced into glass vials and covered with muslin cloth. treatment with water and respective solvents were served as control. the eggs were observed for hatching after 48 hours. 2.6 feeding toxicity of l. nicotianaefolia early 4 th instar larvae of h. puera of uniform age and weight range (36-45 mg) obtained from laboratory culture was used for bioassay. leaf discs of 1.5×1.5 cm size were prepared from freshly collected tender teak leaves. the leaf discs were dipped in the test solution and were placed in the sterilized plastic rearing tube. when the test solution was dried up, test larvae were transferred individually to each tube and allowed to feed for a set period of 3-5 hours. the concentrations used were 0.25%, 0.5%, 1%, 2% and 4%. in the blank group, leaf discs were treated with water and in the control group the discs were treated with solvent. the larvae which have completely fed on the disc alone were transferred into rearing bottles provided with fresh teak leaves. the larvae, which have not fed the leaf discs completely, were discarded. five replications with 10 individuals were used for each concentration. mortality was recorded after 6 hours, 12 hours, 24 hours and 48 hours. 2.7 statistical analysis of the data percentage of larval mortality was calculated. the data was subjected to analysis of variance (anova) and the means separated using least significant difference (lsd). lc50 (lethal concentration) values were calculated using probit analysis according to calculations outlined in finney (1971). probit analysis was carried out using spss software program version 12 and anova was done with agres statistical package. 3. results 3.1 bioassay for contact toxicity larvicidal action the larvicidal activity of the leaf of l. nicotianaefolia against the 3 rd instar larvae of h. puera did not vary among the different extracts. all the treatments were significantly different from the control. the larvae showed restless movement on spraying, and then became inactive and finally succumbed to the test solutions within 2-6 hours of spraying. the dead larvae became distorted and the body wall was later broken and the liquefied body contents oozed out. all the extracts were highly effective causing 100% mortality even with least concentration (0.25%). deepa & remadevi /journal of tropical forestry and environment vol. 5. no 02 (2015) 76-82 79 ovicidal action the ovicidal activity varied among the different extracts. all the treatments did not show any activity and were on par with control except ethyl acetate and water extracts and exhibited highest egg hatch inhibition (80%) and (64%) respectively at highest concentration (2%) (table 1). the least lc50 (0.55%) shows that ethyl acetate extract is better than water extract (1.014%) (table 2). a black spot was present on the dead eggs. table 1: ovicidal activity of various extracts of l. bnicotianaefolia. treatment concentration (%) 2.0 1.0 0.5 ethyl acetate water control 80.00±20.00 (63.44) a 64.00±41.95 (63.44) b 0.00 (0.00) 64.00±32.86 (53.13) b 44.00±45.60 (41.55) c 0.00 (0.00) 48.00±36.33 (43.85) c 24.00±43.35 (29.33) d 0.00 (0.00) sed cd (0.05) cd (0.01) treatment 0.698 1.439 1.962 concentration 0.854 1.763 2.403 t*c 1.208 2.494 3.398 mean±sd represents mean percentage mortality of 5 replicates with 5 individuals each. means followed by the same alphabet does not differ significantly at 5% level of significance. values within parentheses are angular transformed values. table 2: dose mortality response of the eggs of h. puera on contact toxicity with l. nicotianaefolia. treatment lc50 slope±se slope±se chi-square ethyl acetate extract water extract 0.550 1.014 1.48±0.63 2.56±0.66 0.38±0.15 -0.02±0.16 0.014 0.466 chi-square value is less than 3.841 (df=1) is not significant (p>0.05). feeding toxicity figure 1: feeding toxicity of various extracts of l. nicotianaefolia and e. indica on the 4 th instar larvae of h. puera [pe-petroleum ether extract, c-chloroform extract, m-methanol extract, e. al-ethyl alcohol extract, e. ace-ethyl acetate extract, a-acetone extract, w-water extract] 80 based on the potency of l. nicotianaefolia, feeding toxicity tests were performed on 4 th instar larvae of h. puera with petroleum ether, chloroform, methanol, ethyl alcohol, ethyl acetate, acetone and water extracts. the result showed that among all the extracts of l. nicotianaefolia, methanol extract showed highly significant insecticidal activity with mortality of 92%, followed by ethyl alcohol extract (90%) and water (86%). petroleum ether extract was least effective (46%) (figure 1). 4. discussion the larvicidal activity of the leaf extracts of l. nicotianaefolia against the 3 rd instar larvae of h. puera were highly effective causing 100% mortality even with least concentration (0.25%). jayadevi et al. (2003) reported that the cold and hot water extracts of l. nicotianaefolia leaf against plutella xylostella, to be less effective. lobelia excelsa has produced effective control of major pests of cabbage at a concentration of 500 ml ha -1 and has been said to be on par with monocrotophos (0.05%) (rajavel and veeraraghavathatham, 1989) which is in agreement with our finding. l. nicotianaefolia is used by rural communities against insect pests. this plant has rapid knockdown effect similar to that of pyrethrins. the symptoms of death like hyperactivity and convulsions are also as that of pyrethrins, which have neurotoxic action, which block voltage – gated sodium channels in nerve axons (isman, 2006). contact insecticides can kill small insects through suffocation by blocking the spiracles or disruption of cuticular waxes and membranes in the integument leading to desiccation (isman, 2006). moreover, the test insect hyblaea puera is a forest pest and hence it is more sensitive. the 3 rd instar larval stages of h. puera used in the experiment possess soft body which also would have attributed to its rapid mortality at 0.25% concentration. all the treatments did not show any ovicidal activity and were on par with control except ethyl acetate and water extracts and exhibited highest egg hatch inhibition (80%) and (64%) respectively at highest concentration (2%). the study shows that l. nicotianaefolia is not only a larvicide but also an effective ovicide which disagrees with the findings of javaregowda and krishna naik (2007). the low egg hatch inhibition at 2.5% in their study may because of the use of water extract. it is possible that these plant extracts may have one or more chemical substances, which may block the micropyle region of the egg thereby preventing the exchange of gases ultimately killing the embryo in the egg itself. enslee and riddiford (1977) reported that ovicidal activity is due to unequal penetration of extracts through the egg chorion to different parts of egg. similar findings were earlier reported in the eggs of cnaphalocrocis medinalis (saxena et al., 1981), s. litura and percicallia ricini (venkateswarlu, 1988), l. orbonalis (srinivasan and sundarababu, 1999). toxic effects of neoannonin, a novel insecticidal compound isolated from the seeds of annona squamosa to eggs, larvae and adults of drosophila melanogaster have also been reported (kawazu et al., 1989). the disturbance with egg cytoplasm was reflected in the form of dead eggs with black spot stage due to the arresting of further development of embryo inside the egg. bhatnagar and sharma (1994) and elumalai et al. (2005) noticed similar anatomical and physiological disturbances of plant extracts on maize stem borer, chilo partellus. other plants like melia azadarach, strychnous nux vomica, jatropha curcas, cassia fistula, gnidia glauca, ricinus communis, vitex negunda, derris indica, clerodendron inermae, lantana caftera, semecarpus kathalekanesis have been proved to produce varying degree of ovicidal activity on the eggs of h. puera (javaregowda and krishna naik, 2007; ramana, 2005, 2006a). the result of feeding toxicity showed that among all the extracts of l. nicotianaefolia, methanol extract showed highly significant insecticidal activity with mortality of 92%, followed by ethyl alcohol extract (90%) and water (86%). the toxicity could be assessed only at least concentration (0.25%) as deepa & remadevi /journal of tropical forestry and environment vol. 5. no 02 (2015) 76-82 81 the larvae did not feed the leaf discs with higher concentration of the extract. it shows that at higher concentration the extracts had antifeedant activity. our findings are in agreement with the following studies. methanolic extracts from leaves and seeds of chinaberry tree, melia azedarach l. tested against the larvae of h. puera were found to affect the growth, feeding and oviposition of h. puera in the laboratory condition (senthil nathan and sehoon, 2006). ramanna (2006b) reported 74.81% larval mortality at 4% concentration with ethanol extract of the leaves of semecarpus kathalekanensis on the 3 rd instar larvae of hyblaea puera after 24 hours. durairaj (2010) has observed 80% mortality of h. puera larvae within a short period of 24 hours at 2% concentration. his study also reported 60% mortality recorded with 1% oscimum extracts within 48 hours. senthilkumar et al. (2012) reported 100% mortality of the larvae of h. puera at 1000 ppm with methanol and ethyl acetate extract of the leaves of melia dubia, among eight plants tested. in the present study, the symptoms of toxicity caused the rupture of the hind end of the larva and the midgut oozed out along with body fluid, when the larvae consumed the leaf disc treated with the extract of l. nicotianaefolia leaf. this shows that the leaf extract of l. nicotianaefolia is highly toxic. 5. conclusion the results show that lobelia nicotianaefolia has immense potential as insecticide. further work is in progress to use them in bio-pesticide formulation. acknowledgement authors are grateful to institute of wood science and technology, india for the facilities provided and kerala forest research institute, india for helping in bioassays. the first author is grateful to university grants commission, india for the financial assistance. references bhatnagar, a. and sharma, v.k. 1994. insecticidal and ovicidal activities of plant extracts against maize stem borer, chilo partellus (swinhoe). plant protect bulletin 46: 12-16. durairaj, s. 2010. screening of biopesticidal properties of oscimum tenuiflorum l. and parthenium hysterophorus l. against hyblaea puera cramer (hyblaeidae: lepidoptera). current biotica, 4(1): 116-120. elumalai, k., jeyasankar, a., jayakumar, m., raja, n. and ignacimuthu, s. 2005. isolated fractions of hyptis suaveolens and melochia chorcorifolia against the gram pod borer helicoverpa armigera (hubner), in: s.j. ignacimuthu, jayaraj, s. (eds.), sustainable insect pest management, narosa publishing house, new delhi, india, 181-187 pp. enslee, e.c. and riddiford, l.m. 1977. morphological effects of jkm on embryonic development in the bug pyrrhocoris apteru. wilhelm roux’s archives of developmental biology, 181: 163181. isman, m.b. 2006. botanical insecticides, deterrents and repellents in modern agriculture and an increasingly regulated world. annual review of entomology, 51: 45-66. javaregowda, and krishana naik, l. 2007. ovicidal properties of plant extracts against the eggs of teak defoliator, hyblaea puera cramer. karnataka journal of agricultural sciences, 20(2): 291293. jayadevi, h.c., sumithramma, n., nagaraj, n. and kumar, a.r.v. 2003. field evaluation of aqueous extracts of gnidia gluaca and lobelia nicotianaefolia leaves for the management of diamondback moth in cabbage. pest management in horticultural ecosystems, (9)1: 41-47. 82 kawazu, k., alcantara, j. and kobayashi, a. 1989. isolation and structure of neoannonin, a novel insecticide compound from seeds of annona squamosa. agricultural and biological chemistry, 53: 2719-2722. nair, k.s.s., sudheendrakumar, v.v., varma, r.v. and chacko, k.c.1985. studies on the seasonal incidence of defoliators and the effect of defoliators on volume increment of teak. research report, kerala forest research institute, pp. 30-78. nayar, k. k., ananthakrishnan, t.n. and david, b.v. 1979. general and applied entomology. tata mcgraw-hill publishing company ltd., new delhi. rajavel, s.d. and veeraraghavathatham, d. 1989. efficacy of certain plant extracts on the major pests of cabbage. south indian horticulture, 37(3): 186-188. ramana, p. 2005. ovicidal evaluation of chromolaena odorata extracts on teak defoliator-hyblaea puera cramer. my forest, 41(4): 519-524. ramana, p. 2006a. ovicidal evaluation of semecarpus kathalekanensis extracts on teak defoliator, hyblaea puera cramer. journal of non-timber forest products, 13(4): 245-248. ramanna, p. 2006b. larvicidal activity of semecarpus kathalekanensis extracts against teak defoliator, hyblaea puera cramer. my forest, 42(3): 301-305. saxena, r.c., waldbauer, g., liguido, n.j. and puma, b.c. 1981. effects of neem seeds oil on the rice leaf folder cnaphalocrocis medanlis, 1 st international neem conference, rottach egern. 189-204. senthil nathan s. and sehoon, k. 2006. effects of melia azedarach l. extract on the teak defoliator hyblaea puera cramer (lepidoptera: hyblaeidae). crop protection, 25: 287-291. senthilkumar, n., murugesan, s., vijayalakshmi, k.b., monisha, m., suresh babu, d., lakshmidevi, r. and manivachakam, p. 2012. insecticidal properties of certain flora based on ethnobotanical records against teak defloaitor, h. puera cramer (lepidoptera: hyblaeidae). european journal of experimental biology, 2(3): 513-519. srinivasan, g. and sundarababu, p. 1999. ovicidal and ovipositional deterrent effect of neem products on brinjal shoot and fruit borer, lucinodes arbonalis guenee (lepidoptera: pyralidae), in s. ignacimuthu, a. sen. (eds.), biopesticides in insect pest management. phoenix publishing house, new delhi, india, 56-58 pp. venkateshwarlu, p., raghavaiah, g. and nagalingam, p. 1988. effect of neem oil on behavioural aspects of s. litura f. indian journal of pulses research, 1: 118-123. treydte et al., /journal of tropical forestry and environment vol. 3, no. 02 (2013) 53-65 53 wild ungulate distribution in the naban river watershed national nature reserve, southwest china a. c.treydte 1* , p. trumpf 1 , g. langenberger 1 , y.yang 2 , f. liu 2 1 agroecology in the tropics and subtropics, university of hohenheim, garbenstr. 13, 70599 stuttgart, germany 2 naban river watershed national nature reserve, jinghong, yunnan, southwest china date received: 25-05-2013 date accepted: 18-09-2013 abstract southeast asia´s tropical forests harbour a unique diversity of wildlife but species and numbers are rapidly declining under current land use. to improve conservation strategies in these biodiversity hotspots, knowledge of animal species present and their distribution is crucial. we wanted to identify the ungulate community composition and distribution of a ‘man and biosphere’ reserve, the naban river watershed national nature reserve (nrwnnr), yunnan, southwest china. using camera traps, transects, and spoorplots we identified wild ungulate species and corresponding habitat properties. we compared two study sites of different protection status – the buffer and experimental zones – on an overall transect length of 32 km and analysed relationships between wildlife activity, forest vegetation structure, and human disturbance. we documented six ungulate species, all of which occurred in the buffer zone while only three species were found in the experimental zone. wild boar sign density was about 10 times higher in the buffer than in the experimental zone. overall wildlife sign density increased with distance away from human settlements and closer to the core zone. hence, human disturbance strongly influenced wild ungulate abundance but the nrwnnr was found to host a diverse ungulate community, considering its small size and compared to other conservation areas in the region. the combination of various methods proved to be successful in identifying and locating forest wildlife. the nrwnnr, particularly the more strongly protected zones, could greatly contribute to future ecotourism activities in yunnan if a strict preservation of buffer and core zones can be maintained. key words: gaur, protection zones, tropical forest, xishuangbanna, wildlife 1. introduction wildlife in the asian tropics is under severe pressure, particularly in continental southeast asia with its high human population density and intensive rural activities (li et al., 2007). for example, serious declines both in range size and numbers were observed for two charismatic ungulates, the gaur (bos gaurus) and serow (capricornis spec.; sodhi et al., 2004). habitat loss due to land transformation for agriculture and large scale industrial projects such as dams are often the cause for these declines but also hunting for highly priced bushmeat and medicinal products is increasingly depleting wildlife populations (li et al., 2007; sodhi et al., 2010). the extant forest areas in southeast asia are declining drastically in size and have become increasingly isolated (brooks et al., 1999; pattanvibool and dearden, 2002). even where the habitat is still intact – in protected areas – the phenomenon of ‘empty forests’ can be observed, i.e., forests with hardly any signs of animal life (corlett, 2007). although this is a well-known phenomenon, detailed data about the current situation of wildlife populations in such protected areas are scarce. * correspondence: anna.treydte@uni-hohenheim.de tel: +49 711 459 23601 issn 2235-9370 print / issn 2235-9362 online ©2013 university of sri jayewardenepura treydte et al., /journal of tropical forestry and environment vol. 3, no. 02 (2013) 57-70 54 we, therefore, conducted a baseline survey in the naban river watershed national nature reserve (nrwnnr) in the dai autonomous prefecture of xishuangbanna, yunnan, southwest china. as a reserve organized according to the ‘man and biosphere’ reserve concept (barrett and arcese, 1995) it combines zones of varying protection status and represents a mosaic of the major vegetation types described for xishuangbanna (yunnan environmental protection bureau, 2006). here, a high plant biodiversity (ghorbani et al., 2012) and some outstanding wildlife species of critical conservation status can be found, i.e., a population of gaur belonging to the subspecies b. gaurus readei (heinen and srikosamatara, 1993). besides few observational records, little systematic knowledge about the reserve’s current wildlife diversity is available. however, baseline data are urgently needed due to the rapid loss of forest habitats in the buffer and experimental zones and because of the expansion of monocultures, particularly rubber hevea brasiliensis plantations (li et al., 2007). the aim of this study was to assess the presence and distribution of wildlife, especially ungulates, in areas of different protection status within the nrwnnr and relate wildlife locations to human disturbance. the wildlife species composition was compared with similar conservation areas in the region to estimate the relative importance of the nrwnnr for conservation of xishuangbanna’s wild ungulates. 2. methodology 2.1 study site we conducted the wildlife and habitat survey in the naban river watershed national nature reserve (nrwnnr), xishuangbanna dai autonomous prefecture, yunnan province, southwest china during the dry season from october to december 2010 (figure 1). xishuangbanna (21°08’ – 22°36’ north and 99°56’ – 101°50’ east) represents a transitional zone between the tropical climate of southeast asia and the subtropical climate of east asia, characterized by a typical monsoon climate (zhu et al., 2006) with an annual precipitation of 1200 – 1900 mm and average annual temperatures of 15 – 22°c . its flora and fauna has, thus, both tropical and temperate elements (cao and zhang, 1997), creating a biodiversity hotspot. thirty-six percent of china’s birds and 21% of its mammals were documented for xishuangbanna (cao et al., 2006), such as dhole (cuon alpinus), leopard (panthera pardus), gaur, asian elephants (elephas maximus) and tiger (panthera tigris) (zhang et al., 2006; lynam, 2010). the nrwnnr is composed of three zones encompassing different protection status: 1) the ‘core zone’, in which any kind of disturbance and human activity is forbidden, 2) the ‘buffer zone’ where limited agricultural and collecting activities are allowed, and 3) the ‘experimental zone’ comprising agriculture, collecting of natural resources and other extracting activities. to compare the wildlife abundance across different protection zones, we chose the area around guomenshan ranger station (gm, buffer zone) and around xiaonuoyou station (xn, experimental zone; figure 1). the surveyed area at gm covered about 9 km 2 and an altitude of 723 – 1599 masl in the north of the reserve. its topography was dominated by a mountain ridge stretching in east-western direction parallel to the mekong river. the gm area was completely covered by forest and contained few human activities such as footpaths, roads, logging, and livestock-tending activities. in the eastern part, close to the border of the core zone, a settlement existed from 1969 – 1982 but was abandoned thereafter (li, pers. comm.). during winter 2010, the reserve management initiated the construction of a broad footpath and a mineral lick to maintain camera traps for documenting wildlife at gm. in the north-western site of the reserve, xn was located on an altitude range of 1440 – 2024 masl, covering about 12 km 2 . the study area was part of the experimental zone and was covered with forest except for a few agricultural fields and patchily distributed meadows. intensive non-timber-forest-product collecting was documented here (ghorbani et al., 2012). the reserve administration has conducted prescribed understory vegetation burning on the ridges of xn to reduce the prevalent fire risk during the dry season. treydte et al., /journal of tropical forestry and environment vol. 3, no. 02 (2013) 53-65 55 2.2 data collection we assessed wildlife activity using a combination of various methods. we located six north-south walking transects, orthogonal to the mountain ridge (gray and phan, 2011; steinmetz et al., 2008), parallel to each other at a distance of 500 m. at gm, transects were 2 km long, at xn they were 2 – 5.3 km long, in accordance with the forest extension. total transect length was 11.6 km and 20.4 km at gm and xn, respectively. at gm, we walked transects twice to assess animal activity while at xn, we walked transects only once due to time and feasibility constraints. we conducted wildlife species and habitat assessments during diurnal (direct and indirect) observations in nov / dec 2010 and camera trapping data additionally provided information on nocturnal wildlife activity. figure 1: map of the naban river watershed nature reserve (nrwnnr) showing the different protection zones (experimental, buffer, and core zone), villages (black circles), rivers (gray lines) and the location of our two study sites (dashed circles), i.e., guomenshan (gm) and xiaonuoyou (xn). treydte et al., /journal of tropical forestry and environment vol. 3, no. 02 (2013) 57-70 56 during transect walks we documented all identifiable signs of wildlife, mainly hoof prints and dung. we identified signs with the help of rangers and local guides. we attributed different-sized hoof prints, parallel tracks as well as resting grounds next to each other as belonging to different individuals per species (particularly if these species were reported to be single-living) but could not associate up-rooting activity of wild boar, for instance, with only one individual and, hence, recorded these activities as one event at a time. we covered a strip of 2 m along each side of the transect line. at gm, domesticated water buffalos (bubalus arnee) roamed the forest but despite their similar body size to gaur hoof prints of both could easily be discriminated. at gm we established 60 spoor plots of 1 m x 4 m every 200 m along the transects. spoor plots were cleared from litter and raked to detect the number of animals crossing the plot within a known time span until the next inspection (grainger et al., 2005). however, due to generally low animal numbers we reported only few signs on the spoor plots and sampling effort, i.e., re-visiting all plots was time-consuming, so no spoor plots were established at xn. we measured the distance between sign locations and the core zone / the next village on a map. along transects, at 200 m intervals, we established quadrates of 1 m x 1 m each for vegetation surveys, i.e., 64 plots at gm and 22 plots at xn. at each plot we recorded the slope, visually estimated understory vegetation cover to the nearest 5% (kent and coker, 1994) and its average height. for each location we recorded the distance to the nearest tree in all four compass directions as well as the tree trunk diameter at breast height (dbh); we calculated corresponding tree densities (no of trees ha -1 ) using the pointcentred-quarter method (mitchell, 2007). we also installed two reconyx hc600 hyperfire camera traps at areas of expected high wildlife activity such as trails, water holes and foraging places. camera traps were left at each location between 2 and 10 days before we shifted them to another place. additional direct observations and photographs were recorded together with the location of any wildlife spotted in the area. 2.3 data analysis pearson-correlations tested for relationships between animal sign density and vegetation structure (i.e., understory cover, height, tree density) as well as distance to the next village / core zone. the 4 m strip width of the transects was used for calculating relative wildlife sign density (buckland et al., 2001). data were tested for normality and, if needed, transformed accordingly (zar, 1999). student’s t-tests compared wildlife sign density for gm and xn as well as the former settlement region versus gm. one-way anova tests compared wildlife sign densities across the fixed environmental factors tree density, understory height and cover and dbh. the level of significance for our tests was α < 0.05. 3. results 3.1 vegetation structure the two study sites differed in their frequency of disturbance as indicated by signs of local people (number of paths, selective logging, collection activities, livestock herding) but not in their vegetation and environmental characteristics (table 1). the mean tree breast height diameter (dbh), i.e., overall tree age and size, was twice as large at gm compared to that of xn. understory vegetation cover showed large variations, particularly in xn, where it was dense in small valleys and gorges while cover was much lower on top of hills and ridges. this variation was seemingly the result of prescribed burning of the understory vegetation on the drier ridges while some open areas around xn, strongly overgrown by girardinia diversifolia, were intensively used as pasture for domestic water buffalos. treydte et al., /journal of tropical forestry and environment vol. 3, no. 02 (2013) 53-65 57 table 1: means (±sd) and statistical values of student’s t-tests comparing different parameters of forest structure across study sites. gm = guomenshan (buffer zone), xn = xiaonuoyou (experimental zone), dbh = tree diameter at breast height (1.3 m above ground). 3.2 ungulate species documented in the nrwnnr, we documented six wild ungulate species belonging to three different families (table 2): gaur (bos gaurus), sambar (rusa unicolor), red muntjac (muntiacus muntjac), wild boar (sus scrofa), chinese goral (naemorhedus griseus) and chinese serow (capricornis milneedwardsi). the recorded signs were mostly hoof prints and dung and, in case of wild boar, signs of up-rooting activity. we documented most of the species using both by indirect and direct observations. pictures were taken of gaur and chinese goral. the documentation of the chinese serow was based on only two weak hoof print signs only, identified by a local guide, and, therefore, the presence of this species should be taken with care and was not regarded in most analyses (table 2). in total, we found 228 signs of the six ungulate species combined on all transects; at gm (buffer zone), almost twice as many than at xn (experimental zone; table 3). two species, sambar and chinese goral, were only recorded at gm, where we also documented 67 sign events of the wild boar. the number of gaur signs, which was together with wild boar and muntjac found at both sites, was by 25% higher at gm compared to xn; wild boar signs were even four times more frequent in gm than in xn (table 3). muntjac was the only species that occurred more frequently at xn compared to gm. the overall relative wildlife sign density was with 54 signs ha -1 more than three times higher at gm than at xn with 16 signs ha -1 (t = 3.59, p = 0.006, n = 11); wild boar sign densities were seven times greater at gm than at xn (t = 5.22, p = 0.001, n = 11) while other species did not differ significantly (table 3). we found 16% of muntjac signs directly on trails, in contrast to signs of other species. a high proportion of signs was created by only one individual, e.g. in 48% of gaur, 80% of muntjac and 74% of sambar signs. on the other hand, 62% of the signs of wild boar were up-rooting signs, making it impossible to distinguish between one individual spending a longer time there or a group of animals. the latter signs were counted as one event and represented a zone of high activity, often close to trees providing fruits or nuts. 3.3 ungulate species distribution due to low sample size at xn, we analysed only the wild ungulate species distribution at gm. the number of wildlife signs could not significantly be explained by forest vegetation structure. a slight tendency of higher abundance of wild boar, gaur, and muntjac signs at areas of lower understory height was visible (f2,61 = 2.56, p = 0.086). most animals further tended to avoid areas of < 40% and > 80% understory cover (f4,59 = 1.51, p = 0.21). tree density and stem dbh did not significantly influence animal numbers (f3,60 = 1.17, p = 0.328 and f3,63 = 0.29, p = 0.835, respectively). gm xn t p tree density (trees ha -1 ) 2113 (± 1562) 1960 (± 2113) 0.365 0.716 understory height (cm) 65 (± 44) 62 (± 34) 0.305 0.761 understory cover (%) 36 (± 24) 32 (± 25) 0.716 0.476 dbh (cm) 11 (± 10) 22 (± 15) 3.204 0.003 elevation (masl) 1203 (± 155) 1725 (± 137) no. of plots 64 22 treydte et al., /journal of tropical forestry and environment vol. 3, no. 02 (2013) 57-70 58 table 2. list of documented wild ungulate species at the naban river watershed national nature reserve (nrwnnr) and their respective kind of evidence (ps = personal sighting, ph = photograph, s = sign). additionally, the overall number of records and documentations of these species in the nrwnnr and their documentation across other reserves of southeast asia are shown. family scientific name common name evidence no of records in nrwnnr documented in other areas literature suidae sus scrofa wild boar ps, s 82 laos, thailand, vietnam, cambodia timmins 1997, duckworth 1998, pattanavibool and dearden 2002, polet and ling 2004, kitamura et al. 2010, gray and phan 2011 cervidae muntiacus muntjac red muntjac ps, s 56 laos, thailand, vietnam, cambodia timmins 1997, duckworth 1998, pattanavibool and dearden 2002, polet and ling 2004, kitamura et al. 2010, gray and phan 2012 rusa unicolor sambar s 13 laos, thailand, vietnam timmins 1997, duckworth 1998, pattanavibool and dearden 2002, polet and ling 2004 bovidae bos gaurus gaur ps, s, ph 75 laos, vietnam, cambodia timmins 1997, duckworth 1998, polet and ling 2004, gray and phan 2014 capricornis milneedwardsii chinese serow s 2 laos, thailand timmins 1997, duckworth 1998, pattanavibool and dearden 2002, kitamura et al. 2010 naemorhedus griseus chinese goral ps, s, ph 1 thailand pattanavibool and dearden 2002 table 3. number of signs and relative sign density (number of signs ha -1 ) of different wild ungulate species for both study sites gm = guomenshan (buffer zone) and xn = xiaonuoyou (experimental zone). chinese goral was not included in statistical analyses due to low sample size. number of signs sign density t p gm xn gm xn gaur 43 32 8.7 4.2 1.335 0.233 chinese serow 2 28.9 3.7 5.224 0.001 red muntjac 24 32 10.2 8 0.538 0.604 sambar 13 5 wild boar 67 15 0.8 overall 149 79 53.6 15.9 3.593 0.006 the number of signs per plot did not significantly differ but tended to increase with growing distance away from the next village (figure 2a); the average distance of all signs per plot to the next village was with 2.3 km significantly larger at the buffer zone gm compared to 1.8 km at the experimental zone xn (t = 6.21, treydte et al., /journal of tropical forestry and environment vol. 3, no. 02 (2013) 53-65 59 p < 0.001, n = 224). further, the average distance of muntjac signs to the next village at gm was with 2.6 km almost twice as high than that of xn (1.4 km; t = 5.53, p < 0.001, n = 51). the same pattern was visible for gaur with a distance of 2.1 km at gm versus 1.5 km in xn (t = 4.152, p < 0.001, n = 75) while no trend was found for wild boar (t = -0.816, p = 0.417, n = 79). distance to village (in km) < 2 2 2,5 > 2,5 a v e ra g e n u m b e r o f s ig n s 0 1 2 3 4 a) distance to core zone (in km) 1,0 1,5 2,0 2,5 3,0 3,5 4,0 n u m b e r o f g a u r s ig n s 0 2 4 6 8 10 12 14 b) figure 2: a) average number (±se) of all animals signs against increasing distance to the next village (in km). b) number of gaur signs with increasing distance to the core zone (in km), recorded at guomenshan (overall mean = 1.57, standard deviation = 0.69, n = 30). wild boar and muntjac signs were not influenced by the distance to the core zone while 99% of sambar signs were located within a distance of less than 1.7 km away and 83% of gaur signs were found within a distance of less than 2 km (43% in < 1 km) away from the core zone (figure 2b). despite no difference in vegetation structure to the rest of gm, wildlife sign density at the former settlement was about 15 signs ha -1 higher, significantly so for gaur (t = 2.39, p = 0.02, n = 62) and sambar (t = -2.92, p = 0.012, n = 13). relative density of muntjac signs was similar, only the relative density of wild boar signs was higher at gm (figure 3). only 13% of wild boar but 37% of gaur and 62% of sambar signs were found here. re la ti v e w ild lif e s ig n d e n s it y 0 10 20 30 40 50 60 70 wild boar gaur muntjac sambar total figure 3: relative wildlife sign density (number of signs ha-1) recorded on transects at the former settlement area (white bars, n = 12) and the remaining area of guomenshan (black bars, n = 52). treydte et al., /journal of tropical forestry and environment vol. 3, no. 02 (2013) 57-70 60 direct observations were generally difficult due to dense vegetation. sightings of gaur and chinese goral took place in the buffer zone while we directly observed muntjac in the experimental zone only (figure 4). on several occasions, domestic water buffalos passed the camera traps. the camera placed at the experimental zone xn recorded three muntjacs, a female and two males, distinguishable by their antlers (figure 4). (a) (b) (c) figure 4: photographic evidence of a) gaur, b) sambar, and c) muntjac in the naban river watershed national nature reserve (nrwnnr) observed between october and december 2010. photo credit: p. trumpf. 4. discussion 4.1 wildlife species abundance six wild ungulate species were documented in the nrwnnr, including gaur, sambar and chinese goral, all of them ‘vulnerable’ species (iucn, 2011) as well as the more common red muntjac, wild boar, and probably the ‘nearly threatened’ chinese serow species (iucn, 2011). comparable surveys across southeast asia show similar wildlife candidates representing the ungulate communities in forests of thailand, laos, cambodia and vietnam (table 1). wild boar and muntjac occurred in all of these regions (table 1), documenting the rather un-specialized habitat requirements of these species (smith and xie, 2008). both species were even reported to survive in highly degraded landscapes within and surrounding large cities such as hong kong (pei et al., 2010). the habitat at nrwnnr seemed to suit the chinese goral as the only other reserve they were reported at was the om koi wildlife sanctuary in thailand (table 1). the higher wildlife sign numbers in the buffer zone at guomenshan (gm) compared to the experimental zone at xiaonuoyou (xn) was probably due to stronger human disturbance in the latter area where we also detected poachers, logging activities, shelters, hides and fireplaces on several occasions during our surveys. the building of a broad footpath from the road to the former settlement and the installation of mineral licks within the buffer zone might further enhance human activities and consequent human-wildlife encounters. in contrast, animal activity, especially gaur signs, was high within the buffer and directly adjacent to the core zone. this highlights the success of the strict protection management and the corresponding zonation scheme in the nrwnnr. the low abundance of wild boar at the experimental zone xn was probably not due to vegetation structure as they prefer riparian vegetation and gullies (abaigar et al., 1994; caley, 1997), landforms that treydte et al., /journal of tropical forestry and environment vol. 3, no. 02 (2013) 53-65 61 were present at both xn and gm. as the forest at xn was completely surrounded by farmland, wild boar might have been decimated by hunting. muntjac, which can also represent serious pests in farmland (chapman et al., 1994), showed similar sign densities at gm and xn. muntjac generally prefer dense vegetation structures providing cover (chapman et al., 1994; mccullough et al., 2000), which existed at both study sites, thus representing a favourable habitat (pei et al., 2010). sambar and chinese goral were only found in the buffer zone gm, which, in contrast to xn, comprised steep and rocky places, i.e., preferred habitat structures of the goral (chaiyarat et al., 1999; smith and xie, 2008). conversely, for sambar vegetation and terrain seem to be more suitable at xn compared to gm as described by porwal et al. (1996) and varni et al. (2012) while nothing is known about the reaction of sambar to human disturbance. at the nrwnnr, no open or half-open patches were found in the forest, which are often described as preferred ungulate habitat in southeast asia (chodhury, 2002; eisenberg and seidensticker, 1976; wani et al., 2012). sambar in india were reported to intensively utilize open landscapes (wani et al., 2012), generally hiding during daylight in dense vegetation and foraging at night in more open habitats (smith and xie, 2008); hence, this species seems to locally respond to disturbance in a similar way as the red deer (cervus elaphus) in middle europe, changing habitat from open landscapes to forests (rethwisch et al., 2001). similar tendencies to prefer open, agricultural landscapes such as plantations were reported for gaur and sambar in parts of india (balakrishnan and easa, 1986; eisenberg and seidensticker, 1976), which contradicts our findings. this disagreement might be due to the rather small scale and intensive agriculture in addition to poaching activities at nrwnnr and an exhaustive fragmentation of the remaining forest habitats in this region. only one direct observation of a gaur herd of four individuals was made during our study at gm; generally, gaur herds consist of 6 – 8 individuals (bhumpakaphan, 1997). gaur are rather shy and difficult to detect due to their preference of dense bushes (honglian and renchao, 1999). hence, little is known about their habitat preferences, feeding ecology and population structure. gaur numbers have rapidly declined due to hunting and habitat fragmentation (steinmetz, 2004) and they seem to shy away from human disturbance at nrwnnr, which is expressed by their frequent occurrence directly adjacent to the core zone and their scarce occurrence close to human activity hotspots. besides the ungulate species, five other mammal and two larger bird species were documented. twice local guides identified paw prints of an asian black bear (ursus thibetanus) in the buffer zone. a wild cat (leopard cat (prionailurus bengalensis) or marbled cat (pardofelis marmorata)) was caught by the camera trap at xn as well as a striped squirrel (tamiops spec.). near the mekong river, a red jungle fowl cock (gallus gallus) and in xn several silver pheasants (lophura nycthemera) were observed as well as a group of about 10 rhesus macaques (macaca mulatta). 4.2 current situation in our study, wildlife sign numbers generally increased further away from villages and with closer distance to the core zone. hence, the animals at nrwnnr seem to avoid humans, an observation that has been made in several other regions (barnes et al., 1991; griffiths and van schaik, 1993). the forest at the experimental zone xn is smaller in size, surrounded by several villages and crossed by a road, whereas the forest at the buffer zone gm borders villages and a road only at one side, which might be reflected in the animal sign numbers. wildlife, however, can become habituated to disturbance as has been documented for ibex, red deer, reindeer (reimers et al., 2010) and elk (thompson and henderson, 1998). secondary forest growing on abandoned human settlements was shown to be preferred elephant habitat (barnes et al., 1991) and at nrwnnr, the ungulate species present might prefer the abandoned settlement due to better forage quality, lack of human disturbance, relative openness of the vegetation or closeness to the core zone. the increasing problem of hunting of endangered species such as gaur, monkeys and bears for traditional chinese medicine, an eminent threat to biodiversity in the region (mainka and mills, 1995; still, treydte et al., /journal of tropical forestry and environment vol. 3, no. 02 (2013) 57-70 62 2003), might also be threatening the nrwnnr in the future. currently, the destruction of habitats through establishing rubber plantations as well as poaching are probably the most severe threats to the conservation of nrwnnr’s wildlife community. further, large parts of xishuangbanna’s forests have recently been transformed into rubber plantations, seriously affecting the region’s unique biodiversity on a larger scale (li et al., 2007; zhang and cao, 1995). the ungulate community of the nrwnnr is still quite intact, if not in numbers, at least in case of species richness, and has therefore a high value for conservation. a frequent exchange of wildlife subpopulations with other reserves, which can prevent genetic population bottlenecks (amos and balmford, 2008), is barely possible at nrwnnr due to human construction and activities. for example, the adjacent xishuangbanna national nature reserve (xnnr), previously only separated from the nrwnnr by the mekong river, which could be crossed by animals during times of low water levels in the past, is now probably out of reach for most wildlife due to the erection of a dam and the associated rise of the water body. if isolated in the nrwnnr, the local gaur population, which counts probably only about 70 heads (cao, pers. comm.), will soon suffer inbreeding depression, which results in a loss of fitness and can lead to a rapid extinction vortex (e.g. brook et al., 2002). 5. conclusions the naban river watershed national nature reserve is with about 270 km 2 a rather small conservation area and its forests are used for a number of collecting and extracting activities by humans due to its design according to the ‘man and biosphere’ guidelines. the results of this study show that the nrwnnr still hosts a unique wildlife community with an astonishing number of ungulate species. this diversity in combination with the contiguous forests in the buffer and core zone highlights the importance of the nrwnnr as protective area. efforts should be made in connecting this small reserve to existing surrounding reserves and forests using a network of wildlife corridors. this will enable wildlife to recolonize suitable habitats and strengthen the genetic pool. the buffer zone encompassing the abandoned settlement should become part of the core zone and remain under strict protection status as has been proven successful up to now. the installation of camera traps can be a useful tool to reduce poaching. additionally, local people could receive limited allowance to hunt in a sustainable way for their subsistence, which represented a powerful tool in other conservation areas (e.g., elkan et al., 2006). the local community could, in turn, help to monitor wildlife and combat the commercial hunting and trade of wildlife for traditional chinese medicine. acknowledgements: we are grateful to the nrwnnr administration for their interest in and support of this study. tcha-go helped with field work and li lao an, the people of nrwnnr, and w. pfingst provided logistical support. m. cotter, c.q. reimers and i.h. holz helped with statistical and it support. this research was financed by the federal ministry of education and science, germany (bmbf, http://www.bmbf.de/) and ministry of science and technology, p.r. china (most, http://www.most.gov.cn/eng/), funding number 0330797a. references abaigar, t., del barrio, g., vericad, jr., 1994. habitat preference of wild boar (sus scrofa l., 1758) in a mediterranean environment. indirect evaluation by signs. mammalia. 58, 201-210. amos, w., balmford, a., 2001. when does conservation genetics matter? heredity. 87, 257-265. balakrishnan, m., easa, p.s., 1986. habitat preferences of the larger mammals in the parambikulam wildlife sanctuary, kerala, india. biological conservation. 37: 191-200. barnes, r.f.w., barnes, k.l., alers, m.t.p., blom, a., 1991. man determines the distribution of elephants in the rain forests of northeastern gabon. journal of african ecology. 29, 54-63. treydte et al., /journal of tropical forestry and environment vol. 3, no. 02 (2013) 53-65 63 barrett cb, arcese p, 1995. are integrated conservation-development projects (icdps) sustainable? on the conservation of large mammals in sub-saharan africa. world development. 2, 1073-1084. brook, b.w., tonkyn, d.w., o’grady, j.j., frankham, r., 2002. contribution of inbreeding to extinction risk in threatened species. conservation ecology. 6, 1-16. brooks, t.m., pimm, s.l., oyugi, j.o., 1999. time lag between deforestation and bird extinction in tropical forest fragments. conservation biology. 13, 1140-1150. buckland, s.t., anderson, d.r., burnham, k.p., laake, j.l., borchers, d.l., thomas, l., 2001. introduction to distance sampling. oxford university press, oxford. caley, p., 1997. movements, activity patterns and habitat use of feral pigs (sus scrofa) in a tropical habitat. wildlife research. 24, 77-87. cao, m., zhang, j., 1997. tree species diversity of tropical forest vegetation in xishuangbanna, sw china. biodiversity and conservation. 6, 995-1006. cao, m., zou, x., warren, m., zhu, h., 2006. tropical forests of xishuangbanna, china. biotropica 38, 306309. chapman, n., harris, s., stanford, a., 1994. reeves' muntjac muntiacus reevesi in britain: their history, spread, habitat selection, and the role of human intervention in accelerating their dispersal. mammal review. 24, 113-160. corlett, r.t., 2007. the impact of hunting on the mammalian fauna of tropical asian forests. biotropica 39, 292-303. duckworth, j.w., 1998. a survey of large mammals in the central annamite mountains. zeitschrift für säugetierkunde. 63, 239-250. eisenberg, j.f., seidensticker, j., 1976. ungulates in southern asia: a consideration of biomass estimates for selected habitats. biological conservation. 10, 293-308. elkan, p., elkan, s.w., moukassa, a., malonga, r., ngangoue, m., smith, j.l.d., 2006. managing threats from bushmeat hunting in a timber concession in the republic of congo, in: peres, c.a., laurence, w.f. (eds.), emerging threats to tropical forests. university of chicago press, chicago, 395–415. ghorbani, a., langenberger, g., sauerborn, j., 2012. a comparison of the wild food plant use knowledge of ethnic minorities in naban river watershed national nature reserve, yunnan, sw china. journal of ethnobiology and ethnomedicine. 8, 1-17. grainger, m., bonnington, c., dangerfield, s., fanning, e., 2005. the influence of electric fences on large mammal movements in the kilombero valley, tanzania. african journal of ecology. 48, 280-284. gray, t.n.e., phan, c., 2011. habitat preferences and activity patterns of the larger mammal community in phnom prich wildlife sanctuary, cambodia. raffles bulletin of zoology. 59, 311-318. griffiths, m., van schaik, c.p., 1993. the impact of human traffic on the abundance and activity periods of sumatran rain forest wildlife. conservation biology. 7, 623-626. heinen, j., srikosamatara, s., 1996. status and protection of asian wild cattle and buffalo. conservation biology. 10, 931-934. honglian, z., renchao, w., 1999. gis-based ecotope types and their relationship with the survival of bos gaurus readei. chinese journal of applied ecology. 10, 619-622. iucn, 2011. the iucn red list of threatened species. http://www.iucnredlist.org. accessed 20 july 2012. kent, m., coker, p., 1994. vegetation description and analysis: a practical approach. wiley press, chichester. kitamura, s., thong-aree, s., madsri, s., poonswad, p., 2010. mammal diversity and conservation in a small isolated forest of southern thailand. raffles bulletin of zoology. 58, 145-156. treydte et al., /journal of tropical forestry and environment vol. 3, no. 02 (2013) 57-70 64 li, h., ma, y., aide, m.t., liu, w., 2007. past, present and future land-use in xishuangbanna, china and the implications for carbon dynamics. forest ecology and management. 255, 16-24. li, w.y., chan, s.w., guo, d.j., yu, p.h.f., 2007. correlation between antioxidative power and anticancer activity in herbs from traditional chinese medicine formulae with anticancer therapeutic effect. pharmaceutical biology. 45, 541-546. li, h., aide, m.t., ma, y., liu, w., cao, m., 2007. demand for rubber is causing the loss of high diversity rain forest in sw china. biodiversity and conservation. 16, 1731-1745. lynam, a.j., 2010. securing a future for wild indochinese tigers: transforming tiger vacuums into tiger source sites. integrative zoology. 5, 324-334. mainka, s.a., mills, j.a., 1995. wildlife and traditional chinese medicine: supply and demand for wildlife species. journal of zoo and wildlife medicine. 26, 193-200. mccullough, d.r., pei, k.c.j., wang, y., 2000. home range, activity patterns, and habitat relations of reeves' muntjacs in taiwan. journal of wildlife management. 64, 430-441. mitchell, k., 2007. quantitative analysis by the point-centred quarter method. dept of mathematics and computer science, hobart and william smith colleges, arxiv.org. accessed 20 july 2012. pattanvibool, a., dearden, p., 2002. fragmentation and wildlife in montane evergreen forests, northern thailand. biological conservation. 107, 155-164. pei, k.j., lai, y., corlett, r.t., suen, k., 2010. the larger mammal fauna of hong kong: species survival in a highly degraded landscape. zoological studies. 49, 253-264. polet, g., ling, s., 2004. protecting mammal diversity: opportunities and constraints for pragmatic conservation management in cat tien national park, vietnam. oryx. 38, 186-196. porwal, m.c., roy, p.s., chellamuthu, v., 1996. wildlife habitat analysis for ‘sambar’ (cervus unicolor) in kanha national park using remote sensing. international journal of remote sensing. 17, 2683-2697. reimers, e., röd, k.h., flaget, ö., luras, e., 2010. habituation responses in wild reindeer exposed to recreational activities. university of tromsö, http://www.septentrio.uit.no. accessed 20 july 2012. rethwisch, h.g., voreyer, c., austermühle, s., 2001. offenland als rotwildlebensraum der zukunft? – das experiment klepelshagen. workshop proceedings ‘game-friendly use of set-asides’, pp. 162-168. smith, a.t., xie, y., 2008. a guide to the mammals of china. princeton university press, new jersey. sodhi, n.s., koh, l.p., brook, b.w., ng, p.k.l., 2004. southeast asian biodiversity: an impending disaster. trends in ecology and evolution. 19, 654-660. sodhi, n.s., posa, m.r., lee, t.m., bickford, d., koh, l.p., brook, b.w., 2010. the status and conservation of southeast asian biodiversity. biodiversity and conservation. 19, 317-328. steinmetz, r., 2004. gaur (bos gaurus) and banteng (b. javanicus) in the lowland forest mosaic of xe pian protected area, lao pdr: abundance, habitat use, and conservation. mammalia. 68, 141-157. steinmetz, r., chutipong, w., seuaturien, n., chirngsaard, e., 2008. community structure of large mammals in tropical montane and lowland forest in the tenasserim-dawna mountains, thailand. biotropica 40, 344-353. still, j., 2003. use of animal products in traditional chinese medicine: environmental impact and health hazards. complementary therapies in medicine. 11, 118-122. thompson, m.j., henderson, r.e., 1998. elk habituation as a credibility challenge for wildlife professionals. wildlife society bulletin. 26, 477-483. timmins, r.j., 1997. notes on wildlife and habitats in khammouan limestone national biodiversity conservation area, khammouan province, lao pdr. vientiane: centre for protected areas and watershed management and wildlife conservation society, unpubl. report, pp. 1-29. treydte et al., /journal of tropical forestry and environment vol. 3, no. 02 (2013) 53-65 65 wani, m.a., telang, s., bhat, s.a., khursheed, a.s., 2012. habitat utilization of sambar (rusa unicolor niger) in vanvihar national park, bhopal, madhya pradesh, india. indian journal of applied & pure biology. 27, 25-29. yunnan environmental protection bureau. 2006. xishuangbanna nabanhe liuyu guojiaji ziranbaohuqu – xishuangbanna national nature reserve. yunnan science and technology press, xishuangbanna. zar, j.h., 1999. biostatistical analysis. prentice-hall international, new jersey. zhang, l., ma, l., feng, l., 2006. new challenges facing traditional nature reserves: asian elephant (elephas maximus) conservation in china. integrative zoology. 1, 179-187. zhang, j., cao, m., 1995. tropical forest vegetation of xishuangbanna, sw china and its secondary changes, with special reference to some problems in local nature conservation. biological conservation. 73, 229-238. bulafu et al., /journal of tropical forestry and environment vol. 3, no. 02 (2013) 23-38 23 structural changes are more important than compositional changes in driving biomass loss in ugandan forest fragments c. bulafu 1* , d. baranga 1 , a. e. eycott 2 , p. mucunguzi 1 , r. j. telford 2 , and v. vandvik 2 1 department of biology, school of natural sciences, makerere university, p. o. box 7062 kampala, uganda. 2 department of biology, university of bergen, thormøhlensgate 53a, n-5006 bergen, norway date received: 16-08-2013 date accepted: 16-11-2013 abstract aboveground biomass (agb) contained in privately-owned forests is less frequently measured than in forest reserves despite their greater likelihood of degradation. we demonstrate how density changes in contrast to species compositional changes have driven agb changes in privately-owned fragments in uganda over two decades. data on tree assemblages in fragments were obtained by resampling a 1990 dataset in 2010 and agb estimated using generalised allometric equation that incorporates diameter at breast height (dbh) and species-specific wood density. agb were highly variable between fragments and over time. structural changes contributed a higher proportion of change in agb than species compositional changes in all forests. non-pioneer species constituted over 50% of agb in reserve forest, in contrast to private forests where pioneer species dominated. our study demonstrates the potential of private forests to hold comparable agb to plantation. reduction in exploitation pressure is required if fragments are to mitigate carbon emissions. keywords: redd+, kampala, re-sampling, non-pioneer, carbon markets 1. introduction the rate of tropical forests loss, both through deforestation and degradation, is mostly driven by human activities such as land use change and wood extraction (ipcc, 2007). in africa, the role of human activities in these declines shows no signs of abating (mea, 2005; schleuning et al., 2011). deforestation, mainly due to conversion of forests to agricultural land, shows signs of decreasing and in tropical africa it is currently 3.4 million hectares annually and contributes to between 12 and 20% of anthropogenic carbon emissions (fao, 2006; fra, 2010). in addition to deforestation however, degradation in the form of selective logging in both public and private forests is becoming a dominant form of land use change in africa, and large parts of forested areas have been impoverished by this direct form of human activity (asner et al., 2004). despite the clear expectation that degradation pressures varies among public and private forests and that it leads to short and long lived effects on ecosystem processes and functions (mea, 2005), few studies have contrasted private urban and public forests. for instance, the likely alteration of forest potential for carbon storage due to degradation is not completely understood yet. thus based on current projections of forest degradation there is a need to examine how different components of degradation affect ecosystem processes that sustain the provisioning of goods including carbon storage and services to society. forest degradation can be considered as two separate components: firstly timber volume loss through harvesting, which leads to structural changes (tree size and density change) when particular size classes are selected, and secondly species compositional changes which involve shifts from non * correspondence: collinsabc@gmail.com tel: +256776846216 issn 2235-9370 print / issn 2235-9362 online ©2013 university of sri jayewardenepura bulafu et al., /journal of tropical forestry and environment vol. 3, no. 02 (2013) 23-38 24 pioneer to pioneer species in response to selective logging (oliveira et al., 2004). both components can impact forest carbon storage and other ecosystem services. the pioneer species typically have lower wood density and thus retain less carbon per capita than non-pioneer old growth species (tabarelli et al., 2008). both forest structural and species compositional changes towards pioneer species are thus driven mainly by anthropogenic disturbance including logging, firewood production and other extractive activities. partitioning agb change into these two components is necessary to understand the dimensions of the most important drivers of agb change and thus develop a set of sound indicators that can provide meaningful assessment for effective management interventions aimed at maintaining or increasing carbon sequestration in forest fragments. studies that contrast public and private forests have shown that private forests are under the greatest threats and suffer the highest structural and compositional changes (bulafu et al., 2013; naughton-treves et al., 2005) and that agb heavily depends on size class frequency where intermediate-sized (20–50 cm dbh) stems accounted for 46.7% of total agb (nascimento and laurance, 2002). we predict that differences in protection status will lead to high agb loss, which will be driven mainly by forest structural changes, in private forests with low control on access rights compared to public forests. we therefore consider the roles of forest structure (i.e. volume changes) and species composition (i.e. species turnover) in determining the variation in agb between private and public forests. specifically we analysed: (i) the variation in agb between forests and the effect of disturbance and protection status ii) temporal agb changes among forests by size classes, successional status: non-pioneer and pioneer species (iii) agb change due to volume and species turnover and iv) estimate agb for dominant species among forests. inventorying changes in agb and carbon stocks will contribute to understand the role of forests fragments in global carbon cycles and management of existing agb on land for ghg emission mitigation (munishi, 2004). 2. materials and methods 2.1 study sites the study was carried out in the greater kampala area in central uganda (0º 05'n–0º 16'n, 32º 30'e–32º 38'e). the area consists of type c2 piptadeniastrum-albizia-celtis forests whose sizes ranged from 5 to 476 hectares (appendix 1) that extends over gently undulating land between 1200– 1250 m altitude mainly (langdale-brown et al., 1964). the region has annual mean rainfall 1350 mm with bimodal pattern, and annual mean temperature of 25°c (nema 2007). twenty two fragments in our study area were originally surveyed by baranga in 1990 (baranga, 2004). out of these, only 11 forests remained at the time of this repeat survey in 2010 (bulafu et al., 2013). the forests are interspersed within a matrix of agricultural areas (coffee-banana-sweet potatoes), cattle paddocks, human habitations and infrastructural developments. to address temporal changes in agb, we re-sampled remnant forests: three government owned (public) forests (a, b and c) and eight privately owned forests (d – k; baranga, 2004). forest (a) is the nearest reserved forest to the fragments located about 28 km inland from the shore of lake victoria, managed by national forestry authority and was included for comparative purposes. it is classified as a medium altitude moist evergreen forest about 450 ha of type c2 piptadeniastrumalbizia-celtis forest (dawkins and philip, 1962). forest (b) is managed by coffee research institute located inland and consists of naturally regenerating cocoa and tea experimental plots abandoned fifty years ago. eggeling, (1940) provided a detailed description of forest (c) managed by uganda virus institute and located near the shores of lake victoria. four church owned forests (d, e, f and g); three forests owned by private individuals (h, i and j); and one sacred forest controlled and managed by a local community (k) (figure 1) constituted the eight private forests located on private land that are not protected by national law. four of the private forest fragments (d-g) were part of the once extensive lake shore forests of the entebbe peninsula on the heavily indented northern coastline of lake victoria, and are less than 3 km apart (figure 1). over the entire survey period, ownership type did not change for any of the fragments. bulafu et al., /journal of tropical forestry and environment vol. 3, no. 02 (2013) 23-38 25 figure 1: map showing location of the study area and forest fragments. 1.2. field measurements only trees plots minimum diameter at breast height (dbh) of ≥ 3.7 cm measured at 1.3 m above the ground rooted within 10 × 5 m plots established along the transects at 50m intervals were included in the original survey in 1990 and in the present survey (baranga, 2004). for each forest fragment, line transects were established parallel to the longest axis and whose length ranged from 100 to 1000 m depending on forest size and started 10 m from the edge of the fragment. neighbouring transects were separated from each other by 30m. in forest a, transects were set along the already established trail system in a north-south direction but excluding swamp forest stands. the number of transects established and plots sampled are indicated in appendix 1. diameter at reference height (drh) above the buttress was measured for species with buttresses higher than the breast height (sheil et al., 2000). tree stumps were enumerated in 10 × 5 m plots in each forest. tree basal area loss was calculated using dbh of the stumps as an index of biomass outtake. nomenclature followed hamilton (1981). voucher specimens are held at makerere university herbarium. palms encountered in this study were omitted from the analysis as they were not enumerated in the 1990 survey. scores from 1 to 4 were used to assess disturbance status of the forest fragments (1 fairly intact; 2 disturbed; 3 degraded, 4 highly degraded) as follows: (1) presence of a distinct upper and middle canopy, with low density of undergrowth; (2) presence of a distinct upper, middle canopy, with high density of undergrowth; (3) presence of a distinct upper and middle canopy with high number of gaps and evidence of human activities such as tree cutting and forest clearing and (4) presence of only one distinct upper canopy, no or low undergrowth and high number cut trees (figure 5). level of protection was categorised as strict if a guard was employed (forests a-c and i-j,) or weak if no guard bulafu et al., /journal of tropical forestry and environment vol. 3, no. 02 (2013) 23-38 26 was employed by the forest owners (forests d-h). for simplicity species were classified into two ecological groups, whose members share characteristics of importance for determining structure and composition: (i) non-pioneer (ii) pioneer species following (lwanga, 2003). a third category (unknown) was reserved for unidentified species. this classification allows for some generalizations and comparisons. however, we recognize that there might be other subdivisions e.g. (i) shade-tolerant tree species of the lower woody strata of primary forest; (ii) light demanding, relatively long-lived species; (iii) relatively short-lived species requiring gaps for germination and establishment all of which were present in the dataset. forest areas were calculated from shapes delineated from 2010 aerial photographs and comparing with landsat images of both 2010 and 1990 (30 m spatial resolution tm composites) in arcgis 10.0. 1.3 agb and carbon calculations agb here is used to represent only the above-ground portion of live trees ≥ 3.7 cm dbh and excluding palms, vines, litter, dead trees and roots. agb was estimated for each stem with the commonly used moist forest agb equation (chave et al., 2005). data on stem dbh and woody density at genus/species level were incorporated into the allometric equation for agb estimations as adopted by alves et al., (1997). we used a generalised allometric equation for moist forest stands incorporating dbh and species specific values of wood density to estimate agb (chave et al., 2006): (agb) est =ρ  exp (-1.499 + 2.148 ln (dbh) + 0.207 (ln (dbh)) 2 -0.0281 (ln (dbh)) 3 ) where: ρ is wood density (gcm -3 ). species-specific wood densities were taken primarily from the un food and agricultural organisation and world agroforestry's wood density database, supplemented by the prota database www.worldagroforestry.org/sea/products/afdbases/wd/ (following chave et al., 2006). for species with unknown wood density, the mean wood density of all species of the same genus found in the literature search was used, as genus is a good predictor of species wood density (chave et al., 2006). we used agb generated from the above equation to estimate its variation between forests by: i) size class as follows: mature trees > 40cm dbh; adult trees 20-40; young trees 10-20; and saplings < 10 and ii) by successional status i.e. non-pioneer and pioneer species. to investigate the main mechanisms driving agb changes in the forests, we partitioned agb change into structural, compositional and total change as follows: δv=v10 x d90 v90 x d90; δd=v90 x d10 v90 x d90; δ agb=v10 x d10 v90 x d90 where δv is change due to structural (volume) differences only; δd is change due to species compositional differences (density) only; δ agb is total agb change. v10 and v90 are volume in 2010 and 1990 sample regimes respectively; d10 and d90 are weighted mean wood densities of species in 2010 and 1990 sample regimes respectively. to investigate the effects of level protection, disturbance index on agb, we used non-parametric kendall’s rank correlation tau test. forest agb standard errors (se) were calculated as standard deviation divided by the square root of the sample size. finally, tree agb was converted into carbon through multiplication by 0.5 (moist forest equation, chave et al., 2005). data preparation and agb analyses were performed using the r statistical language version 3.0.1 (r core team, 2013). 3. results in 1990, forests showed high variability in the amount of agb, ranging between 99.6 ± 11 t ha -1 and 68.6 ± 9 t ha -1 in public forests and between 55.3 ± 8 t ha -1 and 95.1 ± 11 t ha -1 in private forests while in the current survey agb ranged between 91.7 ± 11 t ha -1 and 83.2 ± 9 t ha -1 in public forests and between 21 ± 15 t ha -1 and 83 ± 9 t ha -1 in private forests (figure 2a). we found that agb decreased with an increase in disturbance index (kendall's tau = -0.674, p = 0.01) while agb increased with protection status kendall's tau = 0.713, p = 0.01). agb differences were seen when bulafu et al., /journal of tropical forestry and environment vol. 3, no. 02 (2013) 23-38 27 comparing tree size distribution in forest fragments or when comparing species ecological successional status (figures 2 a & b). large trees (dbh > 40 cm) contributed between 40-46% of total agb in our forests fragments, while the small trees (< 10 cm dbh) contributed between 8-13% of total agb. non-pioneer species constituted the greatest amount of agb in the public forests while in private forests, pioneer species held the most agb (figure 2b). biomass removal in the current survey showed idiosyncratic trends across size classes with highest removal taking place in the private forests (figure 3). figure 2: agb (t ha-1) estimates per dbh size class (cm) from allometric equation for forest fragments in kampala area divided by (a) dbh size classes and (b) successional status. (full names for sites a-k can be found in table 1) over time, there were high declines in the amount of agb in several of the forests. for example, private forests, particularly church forests e, f and g, had the highest declines in the amount of agb, losing between 40 and 77% (figure 2a). public forests showed minimal declines (figure 2a forest a) or slight increases in amount of agb stored over the two decades, particularly in large sized trees (figure 2a forests b and c). over two decades, biomass change generally showed idiosyncratic trends across size classes (figure 2a). forests i, j and k show compensatory growth in that agb decreased in large-trees, yet in intermediate-sized trees (dbh cm 20-40) agb increased (figure 2a), the highest proportion of change in agb was due to structural changes with species compositional changes playing a minor role, particularly in church forests (figure 4). the covariance, which relates to unequal representation of species across size classes, represented a small fraction of agb change across forest fragments (figure 4). considering the top five species contributing to the most agb across forests, no single species was consistently among the five species of highest per-hectare agb across forests. within forests, the species with the highest agb were not exactly the same five species for each time period. overall, in the non-pioneer successional status group, trilepisium madagascariense dc., pseudospondias microcarpa (a.rich.) engl., antiaris toxicaria (rumph.ex pers.) lesch., sapium ellipticum (hochst.ex krauss) pax and manilkara butugi chiov held 66% of agb while maesopsis eminii engl., piptadeniastrum africanum (hook.f.)brenan, erythrophleum suaveolens (guill. & perr.) brenan, bulafu et al., /journal of tropical forestry and environment vol. 3, no. 02 (2013) 23-38 28 pycnanthus angolensis (welw.) warb., and artocarpus heterophyllus lam. , held 64% of the agb in pioneer successional group (appendix 2). figure 3: distribution of biomass removal (mean stems/ha) per dbh size class (cm) in kampala forest fragments for the current survey. figure 4: change in agb (t ha -1 ) due to volume and density changes over two decades for forest fragments in kampala area. (full names for sites a-k can be found in table 1) bulafu et al., /journal of tropical forestry and environment vol. 3, no. 02 (2013) 23-38 29 figure 5: profile diagram of forest fragments in 2010 for: a) government forest a; b) private forest h; c) church forest f and d) sacred forest k. for forest codes see table 1. 4. discussion aboveground biomass varied strongly between forest fragments under different protection levels and ownership, with public-owned forest holding the highest agb. we additionally found a considerable reduction in agb (and consequently in carbon) over time in privately-owned forests, mainly driven by structural changes in the forests and particularly by significant reductions in stem densities over the two decades in the four size classes investigated. furthermore, large trees contained the majority of agb, our results showed that the importance of medium-sized trees in compensating for loss of large trees in some of the private fragments. in private forests, biomass removal showed idiosyncratic trends across size classes. our forest fragments are in the same climatic region and thus variations in abiotic factors such as soil, rainfall and temperature are too small to have a major effect on agb changes reported here. elsewhere these factors have been shown to have small or no explanatory power for the agb patterns (tabarelli et al., 2010; baraloto et al., 2011). human related disturbance in the form selective logging and fragmentation effects seem to be the prominent factors responsible for the observed variation between forests and over time. in our study sites, the public forests stored more agb and were less affected by structural changes than the more disturbed, private or smaller forest fragments which were under high extraction pressure thus experienced high structural changes. generally, compositional changes played a minor role in the agb changes in our study systems. the forest reserve estimates compare well with those reported elsewhere for similar tropical high forests at normal stocking densities associated with the moist lowland agro-ecological zone of uganda, which ranged between 80 and 180 t ha-1 (drichi, 2003) and other moist forest types elsewhere in africa, e.g. 120-135 t ha-1 in mozambique and 140 t ha-1 in gambia (brown, 1997). the high values of agb in reserved forests can be attributed to low changes in stem density (low structural changes), relatively high density of large trees akin to intact mature forest with minimal anthropogenic disturbances. forest types with larger trees have been shown to accumulate more agb bulafu et al., /journal of tropical forestry and environment vol. 3, no. 02 (2013) 23-38 30 hence more carbon (munishi, 2004). in the private forests, the high volume changes resulted in massive agb declines and we attributed this to high biomass extraction pressure accentuated by the greater annual demand for firewood by the community, as well as to inefficient policing and management by forest owners (bulafu et al., 2013; baranga et al., 2009). we report agb of between 21 t ha-1 and 83 t ha-1 and compared well with hardwood plantations in similar ecological zone, which can store between 88 ha-1 and 90 ha-1 (drichi, 2003). forest subjected to disturbance in the form of selective logging has been shown to have lower agb than their potential (brown, 1997). disturbance and fragmentation both increase forest edge-related effects, consequently reducing forest capacity for agb retention. studies in fragmented brazilian landscapes with high edge effects were shown to retain only one-third as much carbon as forest interior habitat (dantas et al., 2011); the strength of fragmentation effects would probably vary with climate, and forest type. in our study, the largest trees stored most (over 40%) of the agb and carbon, underlining their importance. this agrees with other studies where large trees have been reported to account for more than 30% of agb in mature forests (brown and lugo, 1992; nascimento and laurance, 2002). private forest fragments had fewer large trees compared to the forest reserve and this is again related to anthropogenic disturbance (bulafu et al., 2013). over the re-sample period, our results show a reduction in the amount of agb stored in some fragment, with high declines in basal area across size classes. these changes can be attributed to selective logging of trees and associated forest structural changes (bulafu et al., 2013). in other studies, reduction in agb and carbon retention have primarily been associated with increased mortality of large trees up to 300 m from forest edges (chambers et al., 2001; nascimento and laurance, 2004; alves et al., 2010) combined with a lack of compensatory effect of the remaining canopy and understorey (dantas et al., 2011). for instance, agb of forest edges in the amazonian forest was reduced by one third in just 10-17 years after habitat fragmentation (oliveira et al., 2008). a lesser contribution of large stems would also be expected for habitats that are more heavily logged such as most of our forest fragments (chave et al., 2003; baraloto et al., 2011). we document increases in agb in the intermediate (20-40 cm dbh size class) in three forests in our study that showed marked declines in large sized trees and we interpreted this as a form of compensatory growth. this can be attributed to either recruitment of young trees into intermediate size classes being assisted by reduced competition from mature trees, or by limited or reduced mortality from human exploitation of intermediate size classes for timber or firewood. pioneer species seemed to be responsible for this compensatory effect at least in two of the three forest fragments. the increased mortality of large trees in some fragments may facilitate proliferation of longlived pioneer species. the low value of mean wood density and subsequent per capita carbon relative to old-growth flora, suggest that increased long-lived pioneer species explain the low agb and carbon retention in disturbed forests (tabarelli et al., 2008). rather than making only a minor contribution, dantas et al., (2011) suggest that species replacement is a “key mechanism” in the recovery of biomass in stands where the large trees have been removed, such as the fragments in this study. consequently marked variation in the agb and species turnover of large trees have significant implications for carbon accounting and the future of tropical forests and calls for a better understanding of large tree allometry (goodman et al., 2012). belowground biomass was not measured in this study and estimates of it are scarce, it nevertheless represents an important stock of biomass. in tropical lowland terra firme rainforests in brazilian amazonia, belowground root biomass averaged 20% of agb (sarmiento et al., 2005).using this mean value, root biomass in our forests would range from 5-12 t ha-1 across forest fragments in the current sample. we do not have an estimate of fine litter and coarse dead wood as their dynamics are poorly understood, although it has been estimated that coarse woody debris may be 10 to 40% of the agb and can serve as a long term carbon pool. the amount given by uhl and kauffman (1990) here may be an overestimate for our forests as it is based on relatively intact forests. for large well managed forests, the 2010 value of carbon revenues based on the carbon offset market wide average of $9.2 per tonne of sequestered carbon could present significant revenues gains based on present 2010 agb. africa saw 100% growth in contracted forest credit volumes, with 97% bulafu et al., /journal of tropical forestry and environment vol. 3, no. 02 (2013) 23-38 31 of credits sold to voluntary buyers in the european union. uganda was the 4th largest offset supply country in 2011, mainly from redd+ related projects (peters-stanley et al., 2012). the majority of projects are on private land but increasingly involve communities and smallholder landholders. however, transactional costs for small natural forest owners might be prohibitive to engage in improved forest management so as to benefit from the redd+ carbon credits schemes compared to alternative agricultural land uses. in this case such forest stakeholders can be encouraged to avoid deforestation by the provision and support of alternative sources of income generation such as ecotourism, non-timber forest products production and forest commodity processing. this would help compensate the full range of economic gains that would accrue from deforestation, i.e. the opportunity cost of abandoning less sustainable activities. when combined with restoration activities such forest could have the potential to increase their carbon value. involvement of forest stakeholders in redd+ carbon schemes is dependent mainly on involvement of private-sector institutions seeking to offset emissions to increase demand coupled with appropriate price signals (peters-stanley et al., 2012). 5. conclusion we show massive agb variability between fragments over time. our results confirm our prediction that differences in protection status will translate to noticeable differences in agb loss that were driven mainly by forest structural changes. further, there were differences between private and reserved forest tin term of which species constituted the greatest agb. for instance, non-pioneer species constituted over 50% of agb in reserve forest, in contrast to private forests where pioneer species dominated. our study demonstrates the potential of private forests to hold comparable agb to plantation. reduction in exploitation pressure is required if fragments are to mitigate carbon emissions. 4.1. implications for conservation despite a lower number of large trees in the private fragments compared to reserves and research forests, urban fringe fragments in the kampala area store a considerable amount of carbon relative to plantation forests of similar size, mostly contained in large individuals that remained. proper silvicultural management of these forest fragments, allowing more trees to gain large diameters, has the potential to increase mitigation of carbon emissions. here we present more realistic estimates of the potential of poorly-managed or unprotected fragments to mitigate carbon emissions. in our forests the greatest proportion of change in agb was due to structural changes. at the current rate of agb loss, some of the forest fragments are bound to lose even more of their stored above-ground carbon. the increased proliferation of pioneer species due to anthropogenic disturbances exacerbates this loss. if we are to promote forest fragments for carbon storage, exploitation should be reduced, especially for the large sized trees and late-successional species. however, exploitation is likely to increase in such small, edge-affected fragments as are found in human-modified landscapes such as the kampala area. owners of large and well managed forests fragments can earn money from carbon credit based on the carbon dioxide equivalent. contracting them on the carbon markets will not only reduce carbon dioxide emissions but also present gains for biodiversity conservation, with associated reduction in poverty and improved livelihoods (petersstanley et al., 2012). however, owners of smaller forests might be hampered due to high transactional costs and must engage in proper management practices and restoration activities, particularly for forest fragments that have been severely degraded, in order to benefit from redd+ carbon credits schemes. references alves, d.s., soares, j.v., amaral, s., mello, e.m.k., almeida, s.a.s., silva, o.f., silveira, a.m. 1997. biomass of primary and secondary vegetation in rondônia, western brazilian amazon. global change biology 3: 451–461. alves, l.f., vieirac, s.a., scaranelloc, m.a., camargoc, p.b., santosd, f.a.m., joly, c.a., martinelli, l.a. 2010. forest structure and live above-ground biomass variation along an elevational gradient bulafu et al., /journal of tropical forestry and environment vol. 3, no. 02 (2013) 23-38 32 of tropical atlantic moist forest (brazil). forest ecology and management 260: 679–691. asner, g.p., keller, m., silva, j.n.m. 2004. spatial and temporal dynamics of forest canopy gaps following selective logging in the eastern amazon. global change biology 10: 765–783. baraloto, c., rabaud, s., molto, q., blanc, l., fortunel, c., herault, b., davila, n., mesones, i., rios, m., valderrama, e., fine, p.v.a. 2011. disentangling stand and environmental correlates of aboveground biomass in amazonian forests. global change biology 17: 2677–2688. baranga, d. 2004. forest fragmentation and primates' survival status in non-reserved forests of the 'kampala area', uganda. african journal of ecology 42: 70–77. baranga, d., chapman, c.a., kasenene, j.m. 2009. the structure and status of forest fragments outside protected areas in central uganda. african journal of ecology 47: 664–669. brown, s. 1997. estimating biomass and biomass change of tropical forests: a primer. un fao forestry paper 134. food and agriculture organisation, rome. brown, s., lugo, a.e. 1992. aboveground biomass estimates for tropical moist forests of the brazilian amazon. interciencia 17: 8–18. bulafu, c., baranga, d., mucunguzi, p., telford, r.j., vandvik, v. 2013. massive structural and compositional changes over two decades in forest fragments near kampala, uganda. ecology and evolution, 3, 3804–3823. chambers, j.q., santos, j., ribeiro, r.j., higuchi, n. 2001. tree damage, allometric relationships, and above-ground net primary production in central amazon forest. forest ecology and management 152: 73–84. chave, j., condit, r., lao, s., caspersen, j.p., foster, r.b., hubbel, s.p. 2003. spatial and temporal variation of biomass in a tropical forest: results from a large census plot in panama. journal of ecology 191: 240–252. chave, j., andalo, c., brown, s., cairns, m.a., chambers, j.q., eamus, d., folster, h., fromard, f., higuchi, n., kira, t., lescure, j.p., nelson, b.w., ogawa, h., puig, h., rie´ra, b., yamakura, t. 2005. tree allometry and improved estimation of carbon stocks and balance in tropical forests. oecologia 145: 87–99. chave, j., muller-landau, h.c., baker, t.r., easdale, t.a., ter steege, h., webb, c.o. 2006. regional and phylogenetic variation of wood density across 2456 neotropical tree species. ecological applications 16: 2356–2367. dantas de paula, m., alves-costa, c.p., tabarelli, m. 2011. carbon storage in a fragmented landscape of atlantic forest: the role played by edge-affected habitats and emergent trees. tropical conservation science 4: 349–358. dawkins, h.c. and philip, m.s. 1962. working plan for mpanga research forest. uganda forest department. drichi, p. 2003. national biomass study. technical report. forest department, ministry of water, lands and environment, kampala, uganda. eggeling, w.j. 1940. the indigenous trees of the uganda protectorate. government printer, entebbe, uganda. fao 2006. global forest resources assessment 2005: progress towards sustainable forest management. fao forestry paper. rome, food and agricultural organisation of the united nations. fra 2010. forest resources assessment. fao, forestry paper 163, roma. goodman, r.c., phillip, o.l., baker, t.r. 2012. tropical forests: tightening up on tree carbon estimates. nature 491: 527. hamilton, a.c. 1981 a field guide to uganda forest trees. makerere university printery, kampala. ipcc 2007. climate change 2007: the physical science basis. contribution of working group i to the fourth assessment report of the intergovernmental panel on climate change. in: solomon, s., qin, d., manning, m., chen, z., marquis, m., averyt, k.b., tignor, m., miller, h.l. (eds.), vol. geneva, p. 996, cambridge university press. bulafu et al., /journal of tropical forestry and environment vol. 3, no. 02 (2013) 23-38 33 langdale-brown, i., osmaston, h.a., wilson, j.g. 1964. the vegetation of uganda and its bearing to land-use. uganda government printer, kampala. lwanga, j.s. 2003. forest succession in kibale national park, uganda: implications for forest restoration and management. african journal of ecology 41: 9–22. mea [millennium ecosystem assessment]. 2005. ecosystems and human well-being: biodiversity synthesis. washington, dc, world resources institute, d.c. munishi, p.k.t. 2004. carbon storage in afromontane rain forests of the eastern arc mountains of tanzania: their net contribution to atmospheric carbon. journal of tropical forest science 16: 78– 93. naughton-treves, l., holland, m., brandon, k. 2005. the role of protected areas in conserving biodiversity and sustaining local livelihoods. annual review of environment and resources 30: 219–252. nascimento, h.e.m. and laurance, w.f. 2004. biomass dynamics in amazonian forest fragments. ecological application14 (suppl.):127–138. nascimento, h.e.m. and laurance, w.f. 2002. total above-ground biomass in central amazonian rainforests: a landscape-scale study. forest ecology and management 168: 311–321. nema [national environmental and management authority]. 2007. state of environment report for uganda. nema. kampala. oliveira, m.a., santos, a.m.m., tabarelli, m. 2008. profound impoverishment of the large-tree stand in a hyper-fragmented landscape of the atlantic forest. forest ecology and management 256: 1910–1917. oliveira, m. a., grillo, a.s., and tabarelli, m. 2004. forest edge in the brazilian atlantic forest: drastic changes in tree species assemblages. oryx 38: 389–394. peters-stanley, m., hamilton, k., yin, d. 2012. leveraging the landscape: state of the forest carbon markets. ecosystem marketplace. available at http://www.foresttrends.org/documents/files/doc_3242.pdf (accessed 20 april 2013). r core team 2013 r: a language and environment for statistical computing. r foundation for statistical computing, vienna, austria. isbn 3-900051-07-0. available at http://www.rproject.org/ (accessed 18 april 2013).sarmiento, g., pinillos, m., garay, i. 2005. biomass variability in tropical american lowland rainforests. ecotropicos 18: 1–20. schleuning, m., farwig, n., peters, m.k., bergsdorf, t., bleher, b., brandl, r., dalitz, h., fischer, g., freund, w., gikungu, m.w., hagen, m., garcia, f.h., kagezi, g.h., kaib, m., kraemer, m., lung, t., naumann, c.m., schaab, g., templin, m., uster, d., wagele, j.w., bahning-gaese, k. 2011. forest fragmentation and selective logging have inconsistent effects on multiple animal-mediated ecosystem processes in a tropical forest. plos one, 6(11) e27785. 10.1371/journal.pone.0027785 sheil, d., jennings, s., savill, p. 2000. long-term permanent plot observations of vegetation dynamics in budongo, a ugandan rain forest. journal of tropical ecology 16: 865–882. tabarelli, m., aguiar, a.v., girao, l.c., peres, c.a., lopes, a.v. 2010. effects of pioneer tree species hyperabundance on forest fragments in north-eastern brazil. conservation biology 24: 1654–1663. tabarelli, m., lopes, a.v., peres, c.a. 2008. edge-effects drive tropical forest fragments towards an early-successional system. biotropica 40: 657–661. uhl, c. and kauffman, j.b. (1990) deforestation, fire susceptibility, and potential tree responses to fires in eastern amazon. ecology 71: 437–449. http://www.forest-trends.org/documents/files/doc_3242.pdf http://www.forest-trends.org/documents/files/doc_3242.pdf http://www.r-project.org/ http://www.r-project.org/ http://doi.org/10.1371/journal.pone.0027785 bulafu et al., /journal of tropical forestry and environment vol. 3, no. 02 (2013) 23-38 34 appendix 1: summary of changes in forest fragments (government owned forests (a-c), privately owned forests (d-g church; h-j individual; k sacred) in kampala area for the period 1990 to 2010. forest areas and extent are based on 1955, 1995 and 2010 vegetation maps. disturbance index: 1: fairly intact; 2: disturbed; 3: degraded; 4: highly degraded. forest name code gps coordinates no of transects no. of plots forest size (ha) carbon disturbance index 1990 2010 1990 2010 1995 2010 1990 (t ha -1 ) 1990 total (mt) 2010 (t ha -1 ) 2010 total (mt) 1990 2010 mpanga a 0°13'n, 32°18'e 5 5 50 48 476 438 50 23.8 46 20.15 1 1 kituza b 0°16'n, 32°47'e 5 5 48 49 98 110 34 3.33 42 4.51 1 1 zika c 0°07'n, 32°31'e 3 3 25 23 10 13 34 0.34 42 0.53 1 1 kibale d 0°07'n, 32°32'e 4 4 27 31 42 38 42 1.76 24 0.84 2 2 kisubi technical e 0°07'n, 32°32'e 4 4 20 18 16 10 32 0.51 15 0.14 2 2 gogonya f 0°07'n, 32°32'e 4 4 21 21 15 11 48 0.72 11 0.12 2 3 kisubi girls g 0°07'n, 32°32'e 5 5 47 18 15 13 28 0.42 14 0.18 3 3 wamala h 0°09'n, 32°31'e 6 6 31 30 19 19 45 0.86 29 0.55 2 2 nzuki i 0°09'n, 32°33'e 5 5 20 17 10 10 34 0.34 36 0.36 2 2 bunamwaya j 0°15'n, 32°33'e 7 7 26 23 9 9 38 0.34 32 0.28 3 2 katwe k 0°11'n, 32°27'e 4 4 42 18 18 5 37 0.67 39 0.19 2 2 bulafu et al., /journal of tropical forestry and environment vol. 3, no. 02 (2013) 23-38 35 appendix 2: aboveground biomass (agb t ha -1 ) contribution by the five top tree species dbh ≥ 3.7 cm for forest fragments described in appendix 1 for the two sample periods. see appendix 1 for forest codes; a, b and c government owned whereas d-k are privately or community owned. forests species a b c d e f g h i j k 1990 2010 1990 2010 1990 2010 1990 2010 1990 2010 1990 2010 1990 2010 1990 2010 1990 2010 1990 2010 1990 2010 non pioneer species trilepisium madagascariense dc.* 9.1 4.6 9.9 12.7 10.5 5.5 19.5 4.3 4.1 5.9 6.5 pseudospondias microcarpa (a.rich.) engl.* 12.5 6.5 3.1 2.4 4.0 68.6 12.3 6.5 17.4 antiaris toxicaria (rumph.ex pers.) lesch.* 7.4 3.9 1.7 42.8 4.1 4.3 6.6 5.0 5.8 manilkara butugi chiov.* 8.3 6.0 7.4 13.9 2.1 6.6 sapium ellipticum (hochst.ex krauss) pax* 10.5 5.8 14.4 8.3 13.5 32.0 vespris nobilis engl.* 10.1 5.5 10.4 3.8 5.5 celtis durandii engl.* 14.4 7.3 5.7 5.2 tabernaemontana holstii k.schum* 7.5 5.3 3.8 58.3 celtis mildbraedii engl.* 7.9 14.0 7.0 bulafu et al., /journal of tropical forestry and environment vol. 3, no. 02 (2013) 23-38 36 forests species a b c d e f g h i j k 1990 2010 1990 2010 1990 2010 1990 2010 1990 2010 1990 2010 1990 2010 1990 2010 1990 2010 1990 2010 1990 2010 funtumia elastica (p.preuss) stapf* 5.0 5.6 syzygium guineense (willd.) dc.* 2.8 3.2 blighia unijugata bak.* 4.5 trichilia prieuriana a.juss.* 11.4 6.0 manilkara dawei (stapf) chiov.* 8.8 oxyanthus speciosus dc.* 3.8 pioneer species maesopsis eminii engl. 2.1 6.5 63.6 4.6 10.4 4.4 8.3 4.1 4.2 5.4 piptadeniastrum africanum (hook.f.) brenan 4.4 4.7 3.7 13.4 5.9 19.7 25.2 erythrophleum suaveolens (guill. & perr.) brenan 3.4 13.4 6.0 5.1 4.4 pycnanthus angolensis 5.7 7.1 2.2 1.1 9.2 bulafu et al., /journal of tropical forestry and environment vol. 3, no. 02 (2013) 23-38 37 forests species a b c d e f g h i j k 1990 2010 1990 2010 1990 2010 1990 2010 1990 2010 1990 2010 1990 2010 1990 2010 1990 2010 1990 2010 1990 2010 (welw.) warb. artocarpus heterophyllus lam. 0.7 0.9 5.7 lovoa trichilioides harms 0.7 5.9 8.0 musanga leo-errerae hauman & j.leonard 20.9 4.8 4.4 albizia zygia (dc.) macbr. 8.9 7.4 canarium schweinfurthii engl. 3.1 1.9 macaranga pynaertii de wild. 6.8 7.4 bersama abyssinica fres. 3.4 celtis zenkeri engl. 13.7 eucalyptus grandis w.hill 3.8 milicia exelsa (welw.) c.c.berg 3.4 myrianthus holstii k. 5.9 bulafu et al., /journal of tropical forestry and environment vol. 3, no. 02 (2013) 23-38 38 forests species a b c d e f g h i j k 1990 2010 1990 2010 1990 2010 1990 2010 1990 2010 1990 2010 1990 2010 1990 2010 1990 2010 1990 2010 1990 2010 schum pinus patula schltdl. & cham. 3.3 psidium guajava l. 15.0 tetrorchidium didymostemon (bail.) pax & k. hoffm. 2.5 theobroma cacao l. 15.1 . * non-pioneer species. chapter five: discussion ariyadasa /journal of tropical forestry and environment vol. 5. no 02 (2015) 1-12 1 feature article potential of biomass based electricity generation in sri lanka k.p. ariyadasa * abstract biomass has attracted much attention as a primary energy source for electricity generation due to its potential to supply low cost fuel source with considerable environmental and socio-economic benefits. despite having favorable climatic conditions to grow and use biomass for electricity generation, biomass based electricity generation in sri lanka is lagging behind due to many reasons. many countries rely on the agricultural or forestry by-products or residuals as the main source of biomass for electricity generation mainly due to the comparatively low cost and sustainable supply of these by-products. sri lanka does not have this advantage and has to rely mainly on purposely grown biomass for electricity generation. development of short rotation energy plantations seems to be the best option available for sri lanka to produce biomass for commercial scale electricity generation. the highly favorable growing conditions, availability of promising tree species and a variety of plantation management options and significant environmental and socio-economic benefits associated with energy plantation development greatly favor this option. this paper examines the potential of using plantation grown biomass as a fuel source for electricity generation in sri lanka. keywords: biomass, energy plantations, electricity generation, sri lanka 1. introduction biomass is a renewable resource comes primarily from plants and vegetation that naturally regrows. it mainly comes from agricultural and other industrial processes as a byproduct or residuals while purposely grown biomass for power generation is also available. in recent times, biomass has attracted much attention as a primary energy source for electricity generation due to its potential to supply low cost fuel source with considerable environmental benefits. socio-economic benefits such as local employment generation, mitigation of adverse impacts of climate change and potential carbon trading benefits are among other advantages of using biomass as a fuel source for power generation. coal may be the only fuel source cheaper than biomass but it is responsible for producing the most carbon emissions and other pollutants than any other fuel source. though biomass has the largest share of primary energy supply in sri lanka, which accounts for nearly 45% of the total energy supply, it is mainly used for cooking and heating and has very limited use for electricity generation. despite having favorable conditions in sri lanka to grow and use biomass for electricity generation, biomass based electricity generation is lagging behind due to many reasons. * correspondence: tel: +94 755600515 issn 2235-9370 print/issn 2235-9362 online © university of sri jayewardenepura 2 2. biomass supply chain using biomass for commercial scale power generation is in its infancy in sri lanka. suppliers and supply chains have not yet been developed and it is not clear at present how the biomass supply chain will or should develop. forest based supply chain and agricultural supply chain are the two main supply chains that provide biomass required for power generations (figure 1). figure 1: biomass primary resources input into electricity and heat generation. 2.1 forest based supply chain many countries rely on the forest based supply chain to obtain required biomass for power generation. primary resources from natural forests and forest plantations are divided into four main categories (figure 2).  logging residues including branches and non-commercial stem wood from logging of forests or forest plantations  stumps and root wood from clear cutting areas  round wood not suitable for industrial use  small diameter wood from thinning operations of forest plantations. all natural forests in sri lanka are set apart for conservation and no logging is taking place since the logging ban imposed in 1990. therefore, natural forests cannot be considered as a biomass source for power generation in sri lanka. there are about 85,000 ha of forest plantations in sri lanka and majority of these plantations are used to produce commercial timber. annual production of the plantations is about 150,000 m 3 and logging operations would generate about 35,000 m 3 of residues annually. these logging residues are currently used mainly for fuel wood. forest plantations also produce small diameter timber through thinning operations, especially during the pre-commercial forestry agriculture waste straw/ husk energy plantations other wood chips pellets biogas conversion into electricity & heat ariyadasa /journal of tropical forestry and environment vol. 5. no 02 (2015) 1-12 3 thinning in young plantations. since forest plantations in sri lanka produce comparatively small quantity of industrial wood, less than 10% of the national wood demand, the amount of logging residues generate through logging operations is also very small. as such sri lanka does not have a viable forest based supply chain to provide biomass for commercial power generation. figure 2: primary biomass sources from forests. top left logging residues, top right small diameter thinning materials, bottom left stumps and bottom right non-commercial round wood. 2.2 agricultural supply chain agricultural crop residues play the key role in supplying biomass for power generation in many countries. agricultural supply chain consists of materials from agricultural harvesting and processing (such as rice straw, paddy husk and coconut shells) and other industrial byproducts such as bagasse from sugar industry. 2.2.1 rice straw, paddy husk and coconut shells sri lanka has about 800,000 ha under paddy cultivation and the collective annual paddy production is about 4×10 6 mt in both yala (southwest monsoon period) and maha (northeast monsoon period) seasons. a considerable amount of rice straw is available after rice harvesting and most of it is put back to the rice fields as a soil conditioner and organic fertilizer. therefore, rice straw is not available in sufficient quantities for power generation. every metric ton of paddy would produce around 200 kg of paddy husk and annual production of paddy husk is about 800,000 mt. though this 4 is a sizable quantity, the surplus is rather small as it is already being used in the rice industry for parboiling of rice and in other traditional industries as a source of fuel. problems associated with the collection and transportation of surplus paddy husk further constrains the use of this material in commercial scale power generation. annual production of coconut is around 2.8 billion nuts and a large quantity of coconut shells is produced as a byproduct. as in case of paddy husk, coconut shells are also used as a fuel in traditional industries and small quantity in electricity generation and active carbon production. as such significant quantities are not available for biomass based power generation in commercial scale. 2.2.2 energy plantations energy plantations are one of the main sources of biomass for power generation and sri lanka has a great potential for producing biomass using this source. there are four basic classes of energy plantations with different plant species.  short rotation energy plantations or short rotation coppice (src)  grasses and non-woody energy plantations  agricultural energy plantations  aquatics or hydroponics crops short rotation energy plantations wood from trees has been used for biomass fuel over centuries and traditional forestry has been the primary source of wood. traditional forestry, however, aims at producing sawlogs, pulp and other forest produce in longer rotations and does not suit for producing biomass for energy. short rotation energy plantations or short rotation coppice (src), on the other hand, are managed to produce biomass for power generation in much shorter rotations. this is achieved by producing biomass capturing the highest mean annual growth increment of the tree species used. after the initial establishment of these plantations biomass are obtained through coppicing. the length of coppice rotation and the number of coppices before the next establishment depends on the species used, site conditions and cultural practices. the rotation age can vary from 1-5 years depending on the species. the production capacity of energy plantations depends on the planted species, site conditions of available lands and subsequent cultural practices. there are many fast growing tree species in sri lanka suitable for a variety of site conditions. these species can be used to establish monoculture or mixed plantations under different management regimes to obtain the biomass needed for power generation. sri lanka is primarily divided into three geographical regions namely the dry, intermediate and wet zones and sub-divided in to 24 agro-ecological zones based on the rainfall, topography and soils. though the matching of species with sites needs to be done using standard procedures, the species listed in table 1 can be considered as good candidates for three main climatic regions in the country for short rotation energy plantations. even under rain-fed cultivation these species are capable of producing 10-15 dry tons of biomass per hectare per annum and this can be improved significantly with improved management practices including irrigation and fertilization. ariyadasa /journal of tropical forestry and environment vol. 5. no 02 (2015) 1-12 5 table 1: suitable species for energy plantations. climatic zone suitable species wet zone gliricidia sepium calliandra callothyrus leucaena leucocephala acacia mangium eucalyptus robusta intermediate zone gliricidia sepium calliandra callothyrus leucaena leucocephala dry zone gliricidia sepium leucaena leucocephala acacia auriculiformis among these species g. sepium has been identified as the most promising species for biomass production. apart from wide growing range, easy establishment, ability to manage through coppicing for many years without re-establishment, ideal size of material and good quality of biomass are the desirable attributes of this species. grasses and non-woody energy plantations apart from trees, some grasses can also be used to produce biomass for energy. rhizomatous grasses such as miscanthus species are used in european countries for biomass production. this perennial grass is reported to be produced 14 dry tons of biomass per hectare per year which is comparable with the yield of short rotation energy plantations. illuk (impereta cylindrica) and mana (cymbonogon spp.) are the wide spread natural grasses in sri lanka especially in the dry zone. illuk, like miscanthus, is a rhizomatous perennial grass but it is not capable of producing no more than 5 dry tons of biomass per hectare per year mainly due to the absence of a woody stem like in miscanthus. therefore, the use of locally available grasses for biomass production is not feasible in sri lanka. agricultural energy plantations many agricultural crops have the potential for use as energy crops. they can be used directly as biomass or to provide specific product for a given energy application. sugar crops, starch crops and oil crops are the familiar agricultural crops having the potential for energy applications. there is a very limited potential in sri lanka to get materials from these sources for biomass energy production. bagasse from sugar cane is used to generate part of the electricity needed for sugar industry. the potential of using oil crops such as jatropa to produce bio diesel has been studied but the feasibility for commercial applications is yet to be proven. agricultural residues such as straw and husks and animal residues such as poultry litter have the potential to be used as raw materials for power generation. these materials are not available in sufficient quantities in sri lanka to be used in commercial energy applications and they already have more attractive alternate uses. 6 3. lands development of energy plantations perhaps is the best option for sri lanka to obtain biomass in quantities required for commercial scale power generation. in biomass based electricity generation 1 mw plant would need an extent of 500-1000 ha of lands to produce required biomass fuel depending on the species used, cultural practices and the land quality. therefore, the land, both the availability and quality, perhaps is the single most important factor in developing commercial scale energy plantations. 3.1 availability the biomass based power generation and its favorable impact on the environment, especially on climate change mitigation, depend on the availability of lands to set up energy plantations for supplying biomass required for power plants. the total land area of sri lanka, estimated at 6.5 million hectares, can be categorised into urban, agricultural, crop, forest, range, wet, water and barren land. table 2: land use in sri lanka. land use type description extent (ha) urban land built-up land 22,640 associated non-agricultural land 7,319 homestead 858,000 tree & other perennial crops tea 221,969 rubber 127,000 agricultural land coconut 394,836 cinnamon 8,880 cashew 580 oil palm 1,070 other perennial crops 54,740 paddy 525,338 crop land sparsely used cropland 1,119,665 other crop land 568,232 natural forest forest land dense forest 1,438,275 open forest 429,485 forest plantations (productive) 72,300 range land scrub land 205,630 grass land 105,000 forested wet land mangroves 15,150 non forested marsh 42,400 water 290,520 barren land 77,480 total 6,586,509 source: department of census & statistics and forest department (2012). ariyadasa /journal of tropical forestry and environment vol. 5. no 02 (2015) 1-12 7 homegardens and tree and other perennial crops are the main land use types in agricultural lands while the crop lands include paddy and other annual crops along with a category called sparsely used croplands which accounts for more than one million hectares (table 2). though in many instances the lands under this category have been identified as the potential lands for energy plantation development, there are some practical problems associated with this category of lands. the total extent of this category has apparently been derived by subtracting the known extents of agricultural land uses from the total area of agricultural lands. as such it is very difficult to verify the exact locations and ownership of these lands without extensive ground checking. this category may include some of the areas currently under shifting cultivation and some lands in the forestry sector and estate sector. there is also a possibility to categorise some of the natural ecosystems currently under the protected area network as sparsely used crop lands or barren lands as the boundaries of some of the protected areas are yet be defined. therefore, without a more detailed assessment with ground verification it is difficult to know the exact land extent under the categories of sparsely used crop lands and barren lands. according to the latest forest cover assessment (2010) there are about 430,000 ha or 7% of the land area of the country under the category of ‘sparse and open forests’ which include tropical thorn forests, natural grasslands, savannah forests and scrub lands. there are instances this category of lands has been misinterpreted as degraded lands, may be due to the physical appearance, and has cited as lands available for other development works including growing fuel wood. these are actually naturally occurring vegetation types of the country and should not be used for any other purposes. some of the forest areas, especially in the dry zone, which have been degraded due to shifting cultivation in the past, have been allowed to regenerate naturally to restore the forest cover while providing much needed habitat for wild elephants. under these circumstances a better idea about the potential lands for energy plantations could be obtained by examining the major land uses under state and private ownerships. 3.1.1 state lands majority of state lands is managed by few state agencies namely forest department (fd), department of wildlife conservation (dwlc), mahaweli authority of sri lanka, land reform commission (lrc), privatized planation companies, janatha estate development board (jedb) and sri lanka state plantation corporation (slspc) nearly 30% of the total land area of the country amounting to 2 million hectares is under natural forest cover and managed by the fd and dwlc solely for the conservation of soil, water and biodiversity in order to sustain essential environmental services. as such these lands are not available for any other development projects. a large extent of agricultural lands situated in their command areas is administered by the mahaweli authority of sri lanka and there may be a possibility of obtaining some of these lands for establishing dedicated energy plantations or for mix cropping with other agricultural crops. detailed assessment is needed to identify the exact extents available under different land use types. lrc manages a considerable extent of lands under different land uses and some of these lands are being leased out for various projects including agricultural projects. there may be a possibility of using some of these lands for energy plantation development. 8 3.1.2 privately owned and lease hold lands there is a significant extent of marginal lands in tea and rubber plantations currently managed under lease agreements by the privatized plantation companies and jedb and slspc. some of these lands are being used for forestry and agricultural projects. these estates have the potential of diversifying their operations to produce biomass based electricity on commercial scale as they have the lands, adequate labor, and enough experience in managing short rotation fuel wood plantations. homegardens provide the biggest, and perhaps the best, source of privately owned lands for energy plantations. there are about 900,000 ha of homegardens in the country which accounts for nearly 15% of the total land area. average size of a home garden is ranging from 0.4 ha in the wet zone to 0.8 ha in the dry zone. these lands are used for traditional home garden cropping and some spaces are still available for growing suitable energy crops. with right species and appropriate cropping patterns these lands can be used under out grower system to produce biomass for electricity generation. there are about 395,000 ha of coconut plantations in sri lanka and these plantations can be used to under plant energy crops during the early stage (up to 8 years) and latter part (after 25 years) of the coconut plantation cycle without jeopardizing the coconut yield. if uniform age class distribution is assumed there are about 250,000 ha, of coconut plantations suitable for under planting energy crops. there is a large extent of lands, especially in the dry zone, under shifting (chena) cultivation. though the ownership of lands remains with the state, local people have been engaged in shifting cultivation in these lands for a long period of time. most of these cultivations are seasonal and coincide with the north-east monsoon. energy crops can be incorporated in to the existing chena cultivation under conservation farming systems, especially using alley cropping, where agricultural crops are grown in between the rows of energy crops. as most of the species used for energy plantations in sri lanka are legumes they can improve the soil fertility of shifting cultivation lands which are generally very poor in soil nutrients. though the cultivation of agricultural crops in shifting cultivation areas is taking place only during the north east monsoon, the energy crops can be maintained throughout the year to produce biomass for power generation which will be an additional source of income for local farmers. 3.2 land value post war development has created a big demand for available lands for commercial agriculture. many lands referred to as marginal and barren lands, especially in the dry zone, are currently in high demand for the development of commercial crops. state lands used for shifting cultivation in the dry zone districts are being used for rubber and sugar cane cultivation through state sponsored programs. there is also an increasing demand for lands from the private sector for the development of commercial agriculture crops such as mango and banana. as such the opportunity cost of these lands has been increased considerably during past few years. 4. biomass production as discussed earlier in this paper, energy plantations are one of the main sources of producing biomass. these plantations can be managed either as large scale dedicated plantations or as small scale plantations under out grower systems. ariyadasa /journal of tropical forestry and environment vol. 5. no 02 (2015) 1-12 9 4.1 dedicated energy plantations in the absence of a reliable forest based supply chain or agricultural feedstock chain to obtain biomass as a byproduct or residuals, short rotation energy plantations seems to be the only viable option for producing materials required for commercial scale biomass based power generation in sri lanka. these plantations, especially the dedicated plantations, have the advantage of stability of supply, producing the best quality biomass and increased efficiency in harvesting and processing. at present there is no significant extent of dedicated energy plantations managed for biomass production in sri lanka. 4.2 out-grower systems out-grower systems are capable of using the unutilised and under-utilised resources for the production of biomass without placing too much burden on the existing farming systems. this system can provide much needed lands for energy crops and utilise part of idling labor for the production. this can be seen as a win-win situation as energy plantations are capable of generating additional income without jeopardising the production potential of main crop. however, the maintaining the stability of supply, quality of biomass, and harvesting and processing can be more challenging compared to the dedicated plantation management as a diverse group of people with changing priorities is involved in the production process. cost of production can vary from site to site due to the prevailing socio economic conditions and efficiency of overall management. as described in section 3.1.2, homegardens, coconut plantations and shifting cultivation areas can be used to produce biomass under out-grower systems with suitable tree species and appropriate cropping models. properly implemented out-grower system would be more appealing due to the added environmental and socio-economic benefits. 5. power generation options purpose-grown biomass either in dedicated plantations or through the out-grower systems can be used for power generation in three general applications.  stand-alone, grid-connected biomass-based power plants using plantation grown fuel  cogeneration at other existing facilities such as sugar mills and tea factories for on-site heat and power needs with export of excess power to the national grid using a combination of mill wastes (bagasse, wood waste) and plantation-grown biomass  co-firing at coal -fired electric generation facilities. there are only limited experiences in operating stand-alone biomass based power plants in sri lanka and all aspects of biomass power generation from supply chain to technological options need to be thoroughly studied prior to make substantial investment on this sector. there is, however, a very good potential for cogeneration in other existing facilities especially in tea factories in estate sector. some of these factories already generate heat and electricity for their own use using fuel wood. many estates are in the process of diversification of their operations and biomass based commercial electricity generation could be one of the viable options. some of these estates have marginal lands that could be used for energy plantations and required labour is also available within the existing labor force. they also have the experience in fuel wood plantation management and biomass based power generation which is an added advantage. 10 the third option above, co-firing at coal fired electric generation facilities, would need much more research prior to commence the commercial scale production. 6. technological options the technological options available for biomass based power generation can be broadly categorised into two groups, conventional steam cycle based plants and those based on wood gasification technology. the direct combustion systems involving conventional steam cycle is found to be cheaper in capital cost though the operating efficiencies tend to be around 20%. this established technology is suitable for generation plants with capacities ranging from 1 mw to as high as 50 mw. this may be the most suitable option for sri lankan conditions. the other advanced technologies involve the different wood gasification techniques depending on the scale of capacities. 7. economics of plantation-grown fuels for power generation feasibility studies carried out in sri lanka as well as in some other countries have shown that plantation-grown biomass to produce electricity can be financially viable provided that local resource conditions are favorable and that the cost of conventional power supplies is expensive. in sri lankan conditions biomass based electricity has to compete with the already established hydro and coal power generation. therefore, in order to improve the competitiveness of plantation-grown fuels for power generation would require:  lower cost and sustainable biomass production systems,  more efficient and lower capital cost conversion technologies at scales appropriate for biomass energy applications. the land base and the quality of sites is the key to produce low cost biomass especially in dedicated energy plantations. these two factors determine to a significant extent the degree of site preparation required, the choice of species, spacing, rotation age, required cultural management and soil amendments (fertilization, weed control, animal control, and pest management) and fuel transport and logistics. land and site quality also defines biomass productivity, the major determinant of total feedstock cost. productivity is also a key factor in determining the total size of the plantation, annual feedstock production, and the size of the conversion facility that can be supported. the lands available for dedicated plantations in sri lanka include abandoned shifting cultivation (chena) lands and marginal lands with some physical limitations such as poor soils, low rainfall and lack of irrigation facilities. these lands are small in size and scattered which make commercial energy plantation development more expensive. the biomass production capacity of these lands is likely to be lower without added inputs such as irrigation facilities and fertilizer. under these conditions opportunity cost of lands or land rent need to be significantly low to warrant investments on energy plantations. the lands available for out-grower systems such as homegardens, coconut plantations and other small sized private lands have a comparatively higher biomass production capacity. however, the ariyadasa /journal of tropical forestry and environment vol. 5. no 02 (2015) 1-12 11 development of a system to utilise these lands for biomass production with numerous suppliers is going to be a challenge. 9. information gaps not having reliable information on land base and especially with regard to the production capacities of different species under different climatic conditions has been a problem for prospective investors for some time. land issues are generally complex and the information available on suitable lands for biomass production is insufficient to make commercial investment decisions. therefore, a systematic collection of land data with ground verification is needed to facilitate the investment on biomass based electricity generation. biomass production capacities of plant species varies with the site conditions and subsequent cultural practices. much of the information currently used with regard to the biomass production potential is based on small plot data obtained under more favorable conditions. real world conditions, however, are much different in terms of scale of operation and quality of available sites. therefore, available species need to be tested in different agro ecological regions with most suitable cultural practices along with an economic analysis to obtain reliable information that can be used in the decision making process. 10. case studies case studies are needed prior to getting in to the commercial scale biomass electricity generation as the available experiences are somewhat limited. supply chain options and power generation options can be tested in the field in pilot sites. these studies can be designed to look in to technical, socio economic and managerial aspects. the production potential of biomass using promising species in dedicated plantations, shifting cultivation areas as mixed cropping, home gardens, estate sector and in permanent crops such as coconut plantations can be verified through case studies. these studies need to be designed to examine the aspects of planting, subsequent management, harvesting, transport, post-harvest processing, and storage facilities. different models can be tested in the field to identify the most suitable ones for a given site. power generation models can be tested separately or in conjunction with the biomass production to assess the efficiency, suitability and scale of operations. 11. conclusion there is a very high potential for developing biomass based electricity projects in sri lanka because it has an excellent growing conditions and a variety of tree species are available for energy plantation development to obtain required biomass for power generation. suitable lands are available for biomass production both in state and private sectors but not having a comprehensive land database has been a problem to secure these lands. a variety of power generation and technological options is also available within the country and this could be fine-tuned through further research and case studies. an appropriate mechanism is needed to capture the full environmental and economic benefits of climate change mitigation and potential carbon trade benefits associated with biomass based power generation if this form of power generation to be competitive especially in the face of falling oil prices. 12 references ariyadasa, k.p. 1996. sri lanka profile; in asia pacific agroforestry profiles (2 nd ed). apan field document no. 4 and rap publication 1996/20. asia pacific agroforestry network, bogor, indonesia and food and agriculture organization of the united nations, bangkok, thailand. ariyadasa, k.p. 2002. assessment of tree resources in the homegardens of sri lanka. ec-fao partnership program. food and agriculture organization of the united nations, regional office for asia and the pacific (rap), bangkok 10200, thailand. ariyadasa, k.p. and fedrick, d.j. 1987. above ground biomass estimation for seven tree species grown on the coastal plains of georgia. north carolina state university, raleigh, north carolina. daranagama, u., wijayatunga, p. and ariyadasa, k.p. 1998. feasibility of dendro-power based electricity generation in sri lanka. research report, energy forum, sri lanka. edirisinghe, e.a.p.n., ariyadasa, k.p. and chandani, r.p.d.s. 2012. forest cover assessment in sri lanka. the sri lanka forester, 34: 1-12. jewell, n. 1995. the use of landsat tm data for estimating the area of home gardens. the sri lanka forester. 20 (3,4): 79-86. statistical pocket book, 2012. department of census & statistics, ministry of finance and planning, colombo, sri lanka. wijayatunga, p., daranagama, u. and ariyadasa, k.p. 2005. techno-economic feasibility of biomassbased electricity generation in sri lanka. bioenergy: realizing the potential. elsevier inc. usa. sandeep et al. /journal of tropical forestry and environment vol. 5. no 01 (2015) 1-8 1 feature article evaluating generic pantropical allometric models for the estimation of above-ground biomass in the teak plantations of southern western ghats, india s. sandeep 1* , m. sivaram 2 , k.k. sreejesh 1 and t.p. thomas 1 1 kerala forest research institute, peechi, india 2 southern regional station, national dairy research institute, bangaluru, india abstract the use of suitable tree biomass allometric equations is crucial for making precise and non destructive estimation of carbon storage and biomass energy values. the aim of this research was to evaluate the accuracy of the most commonly used pantropical allometric models and site-specific models to estimate the above-ground biomass (agb) in different aged teak plantations of southern western ghats of india. for this purpose, the agb data measured for 70 trees with diameter >10 cm from different aged teak plantations in kerala part of southern western ghats following destructive procedure was used. the results show that site specific models based on a single predictor variable diameter at breast height (dbh), though simple, may grossly increase the uncertainty across sites. hence, a generic model encompassing dbh, height and wood specific gravity with sufficient calibration taking into account different forest types is advised for the tropical forest systems. the study also suggests that the commonly used pantropical models should be evaluated for different ecosystems prior to their application at national or regional scales. keywords: allometric models, above ground biomass, western ghats 1. introduction estimation of volume, biomass and carbon stocks supports several applications from the commercial exploitation of timber to the global carbon cycle. especially, in the latter context, the estimation of tree biomass with sufficient accuracy is essential to determine annual changes of carbon stored in particular ecosystems. such estimations are the core of carbon sequestration projects (sink projects) dealing with the accumulation and long-term storage of atmospheric carbon in vegetation and soil organic matter. these projects give a better understanding of nature’s carbon sinks, and the valuable information and evidence generated therein will help addressing the physical, natural, social and economic aspects of climate change in a more factual way. tropical forests, which constitute 60% of world forests and 43% of terrestrial net primary productivity (dixon et al., 1994), dominate the role of forests in the global carbon flux and stocks, and hence demand great attention with respect to carbon policies and estimations. in spite of their * correspondence: sandeepagri@gmail.com tel: +91 9495660212 issn 2235-9370 print/issn 2235-9362 online © university of sri jayewardenepura 2 importance to the carbon cycle, there is little information on the carbon budgets of tropical forest systems in south asia. efficient and accurate national systems for measurement, reporting and verification (mrv) systems are required in the region to properly assess carbon stocks and support international climate change efforts. the use of suitable allometric equations is a crucial step in such endeavours, making precise and non-destructive estimation of above and below ground biomass and carbon storage in the region. allometry, generally relates some non-easy to measure tree characteristics (i.e., volume, biomass) from easily collected data such as dbh (diameter at breast height, also denoted as d), total height, or tree age and provides relatively accurate estimates. despite their apparent simplicity, these models have to be built carefully, using the latest regression techniques. tree growth parameters vary considerably with species, site quality, location, climatic regimes, altitude etc. and therefore becomes necessary to obtain accurate and precise tree allometric estimates in order to improve understanding of the role of these carbon sinks in global carbon cycle. an unsuitable application of allometric equation may lead to considerable bias in carbon stocks estimations (henry, 2013). although, large number of allometric equations for estimating above-ground biomass (agb) have been published in south asia during the last decades (sandeep et al., 2014), the pantropical models developed by chave et al. (2005) are widely considered to be the best current approximation for sites for which local equations are not available (clark, 2007). however, the predictive power of these global models differs among sites (chave et al., 2005). for this reason, the evaluation of the accuracy of these models with new data and in different geographic locations is needed. due to the uncertainties in the generic pantropical models, a simplest and most practical approach is based only upon tree diameter at breast height (basuki et al., 2009; alvarez et al., 2012). however, scaling of dbh alone based models to a regional or global scale may have greater uncertainties than more complex models (west et al., 1999; zianis, 2008). inclusion of wood density and tree height has proved to improve biomass estimations considerably (brown et al., 1989; chave et al., 2006; ter steege et al., 2006; wang et al., 2006; patiño et al., 2009). the present work aims to evaluate the accuracy of the most commonly employed pantropical allometric models and simple dbh alone based site specific models to estimate agb in different aged teak plantations of southern western ghats. 2. materials and methods 2.1 tree harvesting and biomass estimation teak plantations in different thinning regimes and at final felling were surveyed in nilambur forest division of kerala state, india and seven sites corresponding to the prescribed felling schedule were selected for the study. presently the thinning operations are performed in teak plantations at the ages of 5, 10, 15, 20, 30, and 40 years and the plantations are clear felled at 50 years. each site represents a specific age. ten randomly selected trees were felled at each of these sites and were used for biomass estimations. before felling, dbh was measured at 1.37 m or above buttresses. the total heights (h) of the trees were measured on the ground using a measuring tape from the base towards the apex of the crown. felled trees were separated into their components (trunk, branches and foliage) and were directly weighed in the field to assess the fresh weight. root systems of the selected trees in each site were excavated manually by starting at the stump and following the roots to possible limits and weighed. sufficient samples of wood, branches and roots were taken from each tree to determine their moisture contents. biomass of various compartments were worked out by estimating sandeep et al. /journal of tropical forestry and environment vol. 5. no 01 (2015) 1-8 3 dry matter of samples by oven drying to constant weight and extrapolation to the whole biomass, which are referred to as measured biomass in this article. 2.2 evaluation of existing allometric models the accuracy of the pantropical allometric models developed by brown et al. (1989), chave et al. (2005), and zianis (2008) (table 1) were evaluated by calculating the relative error in the predicted biomass to measured biomass for each site. the relative error (re) for above-ground biomass (agb) was calculated using equation 1. table1: evaluated pantropical models for estimating the above-ground biomass (dry mass) of tropical trees from their diameter (cm), height (m), and wood density (g cm -3 ). model code allometric models source chave type i exp (-2.187 + 0.916 ln(ρ d 2 h)) = 0.112 (ρ d 2 h) 0.916 chave et al. (2005) chave type ii exp (-2.977 + 0.916 ln(ρ d 2 h)) = 0.0509 (ρ d 2 h) chave et al. (2005) chave type iii exp (-2.557 + 0.940 ln(ρ d 2 h))) = 0.0776 (ρ d 2 h)) 0.940 chave et al. (2005) brown exp (-2.4090 + 0.9522 in (ρ d 2 h)) brown et al. (1989) zianis 0.1424 d 2.3679 zianis (2008) measuredmeasuredpredicted agb)agb(agbre  (1) following chave et al. (2005), the overall biases were evaluated by examining the mean relative error (%), and the accuracy was evaluated by examining the standard deviation of relative error (%) across sites, which represented the overall predictive power of the regression (chave et al., 2005). at a local scale, the simplest models for assessing agb are based upon tree dbh (sierra et al., 2007; litton and kauffman, 2008; basuki et al., 2009). five teak specific allometric models (models 17 in table 2) based only upon dbh, developed in kerala, were evaluated for their accuracy and predictive capacities. however, a simple geometrical argument suggests that the total agb of a tree with diameter d should be proportional to the product of wood specific gravity (oven-dry wood over green volume, denoted by ρ), times trunk basal area (ba=π d 2 /4), times total tree height (h). hence, the relationship should hold across forests as in equation 2: h/4)d (πρfgb 2  (2) table 2: tree biomass models for predicting above-ground biomass (y) of teak plantations in kerala part of southern western ghats. models allometric models model-1 log (y) = 1.606 + 0.197 log (d) model-2 log (y) = 0.636 +1.265 log (d) model-3 log (y) = 0.567 +1.367 log (d) model-4 log (y) = 0.479 +1.374 log (d) model-5 log (y) = -0.150 +1.809 log (d) model-6 log (y) = 1.736 log (d) model-7 log (y)) = 0.685 +1.376 log (d) model-8 y = f x ρ x (πd 2 /4) x h 4 model 8 tries to capture this argument and hence evaluates the efficacy of equations with wood density and height factors rather than dbh alone. the multiplicative coefficient f depends on tree taper and was taken as 0.06 as predicted by cannell (1984) for broad leaved species (chave, 2005). 3. results and discussion the results show that there was a linear increase in dbh of tress with age (figure 1) and there was about 8 cm decadal increases in dbh of teak trees with age. on an average, teak plants yielded 1052.2 kg/tree (agb+roots) of which 60.4% was contributed by wood, 5.6% by bark, 17.4% by branches and 16.5% by roots (data not shown). as percent of agb, root contribution was 20%. though root biomass is as important as shoot in carbon stock estimations, there were very few documents on root growth parameters (sandeep et al., 2014). as a proportion of agb, roots were found to contribute 14%-27% to the total biomass of teak. the decline in ratio of root:agb in teak indicates accumulation of carbon in above-ground portions alone after 30 years. a g e ( y e a r s ) 0 1 0 2 0 3 0 4 0 5 0 6 0 d b h ( c m ) 0 1 0 2 0 3 0 4 0 5 0 6 0 d b h = 0 . 8 0 5 * a g e + 4 . 6 1 r 2 = 0 . 9 8 1 figure 1: trends in mean dbh of trees with age in teak plantations of kerala part of southern western ghats. overall, the chave type of table 1 (2005; hereafter chave i) model had the lowest bias for estimating the total average agb in different sites (-1.5%) (table 3). however, this model was quite unstable at the site scale (22.5%). the type ii model of chave et al. (2005; hereafter chave ii) at the site scale underestimated the average agb of the forests within acceptable limits (-5.0%). the model of brown et al. (1989; hereafter brown) had a similar but positive bias in magnitude at the site scale (9.1%) when compared with chave i and ii but highest uncertainty (26.9%) among the tested models. zianis model (2008; hereafter zianis) though underestimated agb than brown and chave (i and ii) models at the site scale, had the lowest uncertainty. the type iii model of chave et al. (2005; hereafter chave iii), tended to strikingly underestimate the agb across sites with respect to chave i and ii and brown models and had very low stability. the allometric model developed by zianis included only dbh as an explanatory variable. earlier west et al. (1999) and later chambers et al. (2001) showed that agb does not follow a simple power law scaling relation with stem diameter. the sandeep et al. /journal of tropical forestry and environment vol. 5. no 01 (2015) 1-8 5 instability in models with h, ρ and forest types may be due to some fundamental differences in the way ρ was assessed and included in the study. in the present analyses, inferred ρ values were used from the literature which have several disadvantages in comparison to field measurement data because they add an additional amount of uncertainty to the models (chave et al., 2005). table 3: variation in root biomass to agb ratio in teak plantations in kerala part of southern western ghats. age dbh (cm) agb (kg/tree) root to agb ratio min max 10 12.2 19.43 133.31 0.16 20 13.69 27.39 189.21 0.26 30 20.38 36.62 320.97 0.27 40 32.80 44.59 621.04 0.21 50 36.31 59.87 878.47 0.20 mean 340.99 0.21 the inferred ρ data assumed a unique value across the age and dbh classes. in addition to the concerns related to ρ measurement, the changes in the h:d relationship observed in the data set determined by the site variation were not detected by brown and chave model, further restricting their accuracy. all the pantropical models evaluated gave a gross underestimation for dbh values <20 cm and overestimation >40 cm. from the preliminary analysis neither of the evaluated pantropical models could be recommended for application at national or regional scales. the species-specific models used in this study also had higher biases, but were more stable (except models 1, 7 and 8). of the species-specific models at the individual scale, model 3 that used the dbh ranges 10-25 cm was statistically the best of all of the models evaluated (table 5). the study could not conclusively establish that using a single predictor ‘dbh’ in allometric models is an accurate agb estimation method across different sites, though simple and practical. table 4: relative percent error of pantropical equations in evaluating above-ground biomass in different age teak plantations in kerala part of southern western ghats. age (years) chave type i chave type ii chavetype iii brown zianis 5 -38.9 -52.8 -50.7 -38.3 -49.9 10 -44.3 -53.9 -54.2 -42.1 -39.1 15 -46.7 -53.8 -55.6 -43.5 -52.2 20 0.4 -9.3 -15.4 8.3 -14.3 30 6.6 2.1 -8.6 18.0 1.1 40 49.7 56.7 31.6 72.1 23.1 50 62.5 75.8 44.2 89.5 39.0 mean (%) -1.5 -5.0 -15.5 9.1 -13.2 sd (%) 22.5 25.8 20.3 26.9 15.0 model 8 that included dbh, wood density and height showed good performance at the individual site scale at all the evaluated dbh ranges but had very high instability, hence further refinement suggested. the form factor f in model 8 was assumed to be equal to 0.6 for this study, close to the predictions of dawkins (1961) and gray (1966) for broadleaf tree species. however, engineering 6 arguments (mcmahon and kronauer, 1976) suggest that the form factor is not a constant but trees taper as a powerlaw along the main stem. table 5: relative percent error of site specific equations in evaluating above-ground biomass in teak plantations in kerala part of southern western ghats. the assumption of a constant f will grossly reduce the stability of model 8 across dbh and height classes. wood specific gravity is another important predictive variable used in model 8. baker et al. (2004) have reported that ignoring variations in wood density would result in poor overall prediction of allometric models. several workers (brown et al. 1989; nelson et al. 1999; chave et al. 2003; baker et al. 2004) have recommended using a species-level average or a stand-level average of wood density as direct tree density measurements are seldom available. thus a model encompassing d, h and ρ with sufficient calibration for different forest types is advised for the tropical forest systems. 4. conclusion agb quantifications have major implications in assessing ecosystems capacity to sequester carbon. chave i model had the lowest bias for estimating the total average agb in different sites, but was quite unstable at the site scale. zianis model though underestimated agb than brown and chave (i and ii) models at the site scale, had the lowest uncertainty. all the pantropical models evaluated gave a gross underestimation for dbh values <20 cm and overestimation >40 cm. from the present study, neither of the evaluated pantropical models could be recommended for indiscriminate application at national or regional scales. of the species specific models at the individual scale, model 8 that included dbh, wood density and height showed good performance at the individual site scale at all the evaluated dbh ranges but had high instability. the study concludes that a model encompassing d, h and ρ is advised for the tropical forest systems. the model can be made more stable by proper substitution of ρ and form factors considering the age structure and forest types. in this regard, further work is needed to evaluate other available allometric equations besides finding out suitable ρ and form factors. references alvarez, e., duque, a., saldarriaga, j., cabrera, k., de las salas, g., del valle, i., lema, a., moreno, f., orrego, s. and rodríguez, l. 2012. tree above-ground biomass allometries for carbon stocks estimation in the natural forests of colombia. forest ecology and management, 267: 297-308. baker, t.r., phillips, o.l., malhi, y., almeida, s., arroyo, l., di fiore, a., erwin, t., higuchi, n., killeen, t.j., laurance, s.g., laurance, w.f., lewis, s.l., lloyd, j., monteagudo, a., neill, d.a., patino, s., pitman, n.c.a., silva, j.n.m. and vasquez martinez, r., 2004. variation in wood density determines spatial patterns in amazonian forest biomass. global change biology, 10(5): 545-562. models relative error (%) standard deviation model 1 -68.76 20.2 model 2 -19.42 16.3 model 3 -5.69 16.2 model 4 -21.30 13.4 model 5 -26.82 13.2 model 6 -18.20 13.2 model 7 27.30 21.6 model 8 -6.15 55.7 sandeep et al. /journal of tropical forestry and environment vol. 5. no 01 (2015) 1-8 7 basuki, t.m., van laake, p.e., skidmore, a.k. and hussin, y.a. 2009. allometric equations for estimating the above-ground biomass in tropical lowland dipterocarp forests. forest ecology and management, 257: 1684-1694. brown, s., gillespie, a. and lugo, a.e. 1989. biomass estimation methods for tropical forest with applications to forest inventory data. forest science, 35(4): 881-902. cannell, m.g.r. 1984. woody biomass of forest stands. forest ecology and management, 8: 299-312. chambers, j.q., dos santos, j., ribeiro, r.j. and higuchi, n.2001. tree damage, allometric relationships, and above-ground net primary production in central amazon forest. forest ecology and management, 152: 73-84. chave, j., condit, r., lao, s., caspersen, j.p., foster, r.b. and hubbell, s.p. 2003. spatial and temporal variation in biomass of a tropical forest: results from a large census plot in panama. journal of ecology, 91(2): 240-252. chave, j., andalo, c., brown, s., cairns, m.a., chambers, j.q., eamus, d., folster, h., fromard, f., higuchi, n., kira, t., lescure, j.p., nelson, b.w., ogawa, h., puig, h., riéra, b. and yamakura, t. 2005. tree allometry and improved estimation of carbon stocks and balance in tropical forests. oecologia, 145: 87-99. chave, j., muller-landau, h.c., baker, t.r., easdale, t.a., ter steege, h. and webb, c.o. 2006. regional and phylogenetic variation of wood density across 2,456 neotropical tree species. ecological applications, 16(6): 2356-2367. clark, d.a. 2007. detecting tropical forests’ responses to global climatic and atmospheric change: current challenges and a way forward. biotropica, 39(1): 4-19. dawkins, h.c. 1961. estimating total volume of some caribbean trees. caribbean forester, 22: 62–63. dixon, r.k., brown, s., solomon, r.a., trexler, m.c. and wisniewski, j. 1994. carbon pools and flux of global forest ecosystems. science, 263: 185-190. henry m., bombelli a., trotta c., alessandrini a., birigazzi l., sola g., vieilledent g., santenoise p., longuetaud f., valentini r., picard n. and saint-andré l. 2013. glob allome tree: international platform for tree allometric equations to support volume, biomass and carbon assessment. iforest biogeosciences and forestry, 6: 326-330. litton, c.m. and kauffman, j.b. 2008. allometric models for predicting aboveground biomass in two widespread woody plants in hawaii. biotropica, 40(3): 313-320. luizão, f., meir, p., monteagudo, a., neill, d., núñes-vargas, p., peñuela, m.c., pitman, n., priante filho, n., prieto, a., panfil, s.n., rudas, a., salomão, r., silva, n., silveira, m., soares de almeida, s., torres-lezama, a., vásquez-martínez, r., vieira, i., malhi, y. and phillips, o.l. 2009. branch xylem density variations across the amazon basin. biogeosciences, 6: 545–568. mcmahon, t.a. and kronauer, r.e. 1976. tree structures: deducing the principles of mechanical design. journal of theoretical biology, 59(2): 443-466. nelson, b.w., mesquita, r., pereira, j.l.g., de souza, s.g.a., batista, g.t. and couto, l.b. 1999. allometric regressions for improved estimate of secondary forest biomass in the central amazon. forest ecology and management, 117: 149-167. sandeep, s., sivaram, m., henry, m. and birigazzi, l. 2014. inventory of volume and biomass tree allometric equations for south asia.kfri, peechi, india. un-redd programme mrv report, 15, food & agriculture organization of the united nations, rome, italy. sierra, c.a., del valle, j.i., orrego, s.a., moreno, f.h., harmon, m.e., zapata, m., colorado, g.j., herrera, m.a., lara, w., restrepo, d.e., berrouet, l.m., loaiza, l.m. and benjumea, j.f. 2007. total carbon stocks in a tropical forest landscape of the porce region, colombia. forest ecology and management, 243: 209-309. 8 ter steege, h., pitman, n.c.a., phillips, o.l., chave, j., sabatier, d., duque, a., molino, j.f., pr´evost, m.f., spichiger, r., castellanos, h., von hildebrand, p. and vásquez, r. 2006. continental-scale patterns of canopy tree composition and function across amazonia. nature, 443: 444-447. wang, x., fang, j., tang, z. and zhu, b. 2006. climatic control of primary forest structure and dbh height allometry in northeast china. forest ecology and management, 234: 264–274. west, g.b., brown, j.h., enquist, b.j., 1999. a general model for the structure and allometry of plant vascular system. nature, 400: 664-667. zianis, d. 2008. predicting mean above ground forest biomass and its associated variance. forest ecology and management, 256: 1400-1407. divakara /journal of tropical forestry and environment vol. 4. no 02 (2014) 11-23 11 relationship of seed traits on initial progeny growth performance and divergence studies in madhuca latifolia macb. for further use in tree improvement b.n. divakara 1* 1 institute of wood science and technology, mellashwaram, bangalore, india date received: 18-01-2013 date accepted: 03-07-2014 abstract evaluation of 23 genotypes of madhuca latifolia was carried out based on relationship of seed traits with initial progeny growth performance and divergence studies as a scope for further breeding programme. variability studies revealed that, more than 12 accessions recorded above average for 100seed weight (247.5±49.2), oil content (43.8±3.7) and volume index (346.0±97.7). the maximum values observed in studied cpts were as follows: seed length (39.1 mm) in cpt-15 genotype, seed breadth (19.2 mm) in cpt–8 and cpt–9, aspect ratio (2.2) in cpt-6 and cpt-15, 2d surface area (501.4 and 491.6 mm 2 ) in cpt-9 and cpt-3 respectively. cpt–16 recorded maximum for 100 seed weight (282.4 g) and oil content (51.2%). however, maximum volume index was recorded by cpt–3 (578.3 cm 3 ) followed by cpt–16 (496.0 cm 3 ). the phenotypic and genotypic coefficients of variations are close to each other for all traits, except volume index that exhibited striking difference between pcv (40.0%) and gcv (19.9%) indicating that for most traits genetic control was quite high. trait oil content and 100 seed weight expressed high heritability (93.5%, 93.0%) accompanied with moderate genetic advance (17.2%, 15.6%), indicating that, heritability is due to additive gene effects and selection may be effective. at genotypic level 100 seed weight registered positive significant correlation with plant height (0.73), oil content with volume index (0.71). hence seeds with large breadth, high seed weight and oil content may be selected for producing better progenies. since traits viz. 100 seed weight and oil content are under strong genetic control, improvement in these characters can bring improvement in volume index. on the basis of the divergence, the 23 genotypes studied were grouped into 5 clusters, indicating wide diversity. the clustering pattern shows that geographical diversity is not necessarily related to genetic diversity. the genotypes in cluster iv and v were most heterogeneous and can be best used for within group hybridization. cluster means indicated crosses involving under cluster ii and v and cluster ii and i may result in substantial segregates and further selection for overall improvement of species. keywords: madhuca latifolia, heritability, genetic advance, genetic divergence, correlation 1. introduction madhuca latifolia macb. (syn m. indica j.f. gmel; bassia latifolia roxb.) of family sapotaceae, vernacularly and commonly known as mahua and indian butter tree is a large, branched deciduous tree indigenous to the indian subcontinent. it is predominantly grown in dry tropical and * correspondence: bndsira@gmail.com tel: +91 8022190198 issn 2235-9370 print/issn 2235-9362 online © university of sri jayewardenepura 12 sub-tropical regions of indo-pakistan subcontinent. the species is scattered in deciduous forests and dry sal plain forests. plant grows upto 18 m height with short bole, grey to black bark and round crown. it is extensively cultivated in villages of northern india and deccan peninsula for sweet fleshy corolla and ripe fruits which is used as a major source of industrial alcohol as well as country liquor, portable spirit and vinegar. seeds contain a valuable fatty oil ranging from 38% to 57%, known as mahua oil or butter of romance. mahua oil is used as edible oil, manufacture of margarine, soap, glycerin, lubricating grease and medicine. seed cake is used as biofertilisers, organic manure, biocide and fish meal. its leaves used for fodder and green manure while bark gives tannin (csir, 1998). due to presence of similar properties to that of diesel, mahua oil has gained the importance as bio-diesel and is emerging as a viable alternative to fossil fuel. importantly, the successful adoption of bio-fuels is reliant on the supply of feedstock from non-food crops with the capacity to grow on marginal land not destined to be used for the cultivation of food crops (hill et al., 2006). meeting both of these criteria and thus, can form the basis of a highly promising, profitable, and self-sustaining platform for smallscale entrepreneurship and self-employment in rural areas, ensuring optimum utilisation of wasteland resources and unemployed manpower. although m. latifolia is well known as oil yielding tree having wide adaptability and plethora of uses, little attempt has been directed to improve it as a crop plant because of long gestation period and slow growing nature. the wide gap in potential and actual yield is due to the use of locally available wild material. no systematic breeding program for breeding superior high yielding genotypes has been initiated. m. latifolia being open pollinated crop (anemophillic), provide ample scope for genetic improvement through selection of superior trees with genetic variation in seed morphology and oil content along with initial progeny performance which later can be of great potential and may have greater impact than the conventional breeding. hence, the challenging task, as of today is to screen the naturally available m. latifolia genetic resources to select the best planting material with high oil content for higher productivity. the available information in literature does not provide a complete understanding of geographical variation and its influence on improvement of seed quality and quantity. the information on the genetic structure and diversity relationship of candidate plus trees provide a basis for planning and conducting future collections and efficient utilization of genetic resources to realize the potentiality for maximizing seed and oil yield. keeping precarious scenario in view, an effort was made to investigate the relationship of seed traits with initial progeny growth performance for early selection and divergence studies to understand the diversity among 23 accessions for assessment and creation of diverse lines in m. latifolia for further use in tree improvement. 2. material and methods an extensive wild germplasm exploration survey was conducted to identify the high yielding candidate plus trees (cpts) of m. latifolia at fruiting stage from different predominant naturalized locations in jharkhand, india (table 1, figure 1). the selection was made on phenotypic assessment of characters of economic importance viz yield potential, crown spread, total height, girth at breast height, age of the tree, free from pest and diseases, seed size and seed weight. a total of 23 cpts (morphologically superior trees) covering a latitude and longitudinal range between 22 0 00 / n to 24 0 50 / n and 83 0 30 / e to 87 0 00 / e, respectively, were selected (table 1). from each cpts, 2 kg of mature capsules were collected during june-july, 2005. quantitative characterization was carried out (6 seed and 3 progeny characters) at forest research centre, institute of forest productivity mandar, ranchi district during 2005-07. divakara /journal of tropical forestry and environment vol. 4. no 02 (2014) 11-23 13 2.1 site characteristics the study area under forest research centre (latitude: 23 0 27′ 40″ n, longitude: 85 0 05′ 56″ e, altitude 2,320 ft msl approx.) has a semi-arid type of climate. mean annual rainfall is 1231.6 mm with mean number of rainy days 73.6. annual minimum and maximum temperature is recorded as 17.7 0 c and 30.2 0 c respectively with lowest temperature in january and highest temperature in may. soils of the study area is characterized by ph (5.7), ec (35), organic carbon (0.33%), nitrogen (105 ppm), phosphorus (11 ppm) and potassium (74 ppm). 2.2 seed characters samples of 300 seeds were randomly collected from each cpt to make three replicates with 100 seeds in each. measurement of morphological traits viz. seed length, seed breadth, aspect ratio and 2d surface area, was carried out using image analyzer (leica quantimet called qwin 500). seeds were spread on a glass platform of macro-viewer for each replication and images were captured using charge coupled device (ccd) camera. these images were analysed using quantimet 500+ or qwin software. the qwin identifies the object based on given specification for seed colour and calibrates captured images to actual scale. different two dimensional (2d) measurements of the detected images were measured (table 2). 2 2 2 figure 1: distribution of madhuca latifolia candidate plus trees in jharkhand, india mapped using microsoft encarta 2005 note: details of number representation is in table 1. 14 table 1: locational details of madhuca latifolia candidate plus trees (cpts) selected in jharkhand, india. cpts district location/village latitude longitude alt, m age, yr h, m d, cm seed yield, kg yr -1 crown area (m 2 ) cpt-1 lohardaga chingri nawatoli 23° 26' 19 n 84° 18' 25 e 590 95 10.0 80 300 294.19 cpt-2 simdega pharsabera kusumtoli 22° 39' 17 n 84° 31' 56 e 410 65 13.6 90 100 191.21 cpt-3 gumla samra velluwa toil 23° 03' 03 n 84° 52' 28 e 520 80 15.3 53 120 123.75 cpt-4 simdega piosokra 22° 36' 06 n 84° 43' 01 e 370 80 17.5 119 180 331.81 cpt-5 latehar hotwag 23° 47' 28 n 84° 27' 08 e 340 70 15.3 70 120 247.55 cpt-6 daltonganj sarja polpol 23° 54' 17 n 84° 31' 21 e 290 45 13.8 70 70 166.34 cpt-7 daltonganj akhra 23° 55' 59 n 84° 10' 23 e 250 100 14.4 110 200 481.30 cpt-8 garhwa singakala 23° 55' 18 n 83° 44' 15 e 385 100 13.6 110 200 452.57 cpt-9 garhwa garbandh 24° 21' 24 n 83° 28' 39 e 510 60 10.3 85 150 166.34 cpt-10 daltonganj simarbar batawa 24° 27' 39 n 84° 13' 04 e 215 70 12.0 74 100 247.55 cpt-11 chatra pitiz 24° 15' 19 n 85° 06' 50 e 375 40 10.3 55 30 133.81 cpt-12 latehar nachna 23° 51' 54 n 84° 49' 44 e 540 120 9.8 103 200 216.51 cpt-13 ranchi piska mahua toli 23° 28' 03 n 85° 26' 24 e 610 50 14.0 60 150 203.67 cpt-14 hazaribag ahoanhe moraha 23° 49' 37 n 85° 24' 55 e 510 40 10.2 54 70 166.34 cpt-15 koderma banpok 24° 34' 36 n 85° 42' 47 e 390 80 10.2 70 100 125.73 cpt-16 giridih madhgopali 23° 56' 56 n 86° 00' 44 e 340 70 11.0 78 100 212.62 cpt-17 chaibasa khas jamda 22° 09' 08 n 85° 29 54 e 550 70 12.8 80 100 229.75 cpt-18 saraikela palobera 22° 15' 52 n 85° 59' 14 e 300 45 15.4 65 60 243.38 cpt-19 jamshedpur golkatta 22° 39' 02 n 86° 27' 09 e 190 50 12.7 52 70 128.73 cpt-20 chaibasa junko 22° 45' 19 n 85° 26' 25 e 450 50 17.7 70 100 308.03 cpt-21 ranchi panimahua chamma 23° 32' 27 n 85° 06' 17 e 650 50 14.0 60 150 203.67 cpt-22 dhanbad kokra 23° 59' 50 n 86° 30' 45 e 240 90 14.3 97 100 274.76 cpt-23 latehar chandwa 23° 41' 42 n 84° 43' 36 e 520 80 13.8 106 120 335.05 2.3 the progenies seeds of all the cpts were pre-treated by soaking in cold water for 24 hours. pretreated seeds of each cpts were directly sown in polythene bags of dimension 30×12×10 cm filled with potting mixture of soil, sand and farmyard manure (2:1:1) in three replicates of 100 seeds each, during july 2005. samples of six one-year-old seedlings were planted with spacing of 3.5×3.5 m in the field with (pit size 45×45× 45 cm) for field evaluation at forest research centre in july 2006. randomised complete block design (rcbd) with three replicates was used. after 30 months of sowing (juvenile stage), observations were recorded on the trial for plant height (m) and collar diameter (cm) were measured at bimonthly intervals over a period of 18 months. the data recorded at 18 months after sowing (mas) alone was considered for variability, correlation and diversity studies. the results are given in the (table 3). table 2: methodology for measuring seed and progeny traits of madhuca latifolia. sl. no. traits method 1 seed length (mm) length of the seed at longest side. 2 seed breadth (mm) length of the seed at shortest side. 3 aspect ratio length was divided by breadth. 4 2d surface area (mm 2 ) 2d surface area of the seed in the direction of measurement. 5 100 – seed weight (g) weight of 100 seeds weighed on electronic balance was measured in grams. 6 oil content (%) estimated using soxhlet apparatus following the procedure of sadasivam and manickam (1992). 7 plant height (cm) length of the plant from ground level to tip. 8 collar diameter (cm) stem diameter near the ground level. 9 volume index (cm 3 ) [collar diameter (cm)] 2 × plant height (cm)] (manavalan 1990). divakara /journal of tropical forestry and environment vol. 4. no 02 (2014) 11-23 15 2.4 data analysis the seed parameters and progeny measurements were analysed using analysis of variance (anova) and duncan multiple range test (dmrt) to understand the significance of differences between the seeds and progenies of cpts (gomez and gomez, 1984). the phenotypic variation for each trait was partitioned into components based on genetic (hereditary) and non-genetic (environmental) factors and estimated using the following formula (johanson et al., 1955): vp = msg/r; vg = (msg – mse)/r; ve = mse (1) msg, mse and r are the mean squares of cpts, mean squares of error and number of replications, respectively. the phenotypic variance (vp) is the total variance among phenotypes when grown over the range of environments of interest, the genotypic variance (vg) is the part of the phenotypic variance that can be attributed to genotypic differences among the phenotypes, and the error variance (ve) is part of the phenotypic variance due to environmental effects. to compare the variation among traits, phenotypic (pcv) and genotypic (gcv) coefficients of variation were computed according to the method suggested by burton, (1952) pcv = (√vp/x) × 100; gcv = (√vg/x) × 100 (2) vp, vg and x are the phenotypic variance, genotypic variance and grand mean for each pod and seed-related trait, respectively. broad sense heritability (h 2 b) was calculated according to allard (1999) as the ratio of the genotypic variance (vg) to the phenotypic variance (vp). genetic advance (ga) expected and ga as per cent of the mean assuming selection of the superior 5% of the genotypes were estimated in accordance with johanson et al., (1955), as in the following equation. ga = k·h 2 b·√vp; ga (as % of the mean) = (ga/x) × 100 (3) k is the selection differential (2.06 for selecting 5% of the genotypes). phenotypic (rp) and genotypic (rg) correlations were further computed to examine inter-character relationships among seed and seedling traits following goulden (1952) as given below. rp = covp (x1, x2)/[vp(x1)·vp(x2)] ½ (4) rg = covg (x1, x2)/[vg(x1)·vg(x2)] ½ (5) covp and covg are phenotypic and genotypic covariances for any two traits x1 and x2, respectively, and vp and vg are the respective phenotypic and genotypic variances for those traits. the genetic diversity was estimated using the mahalanobis d2 statistics (mahalanobis, 1936). tracing d 2 as a generalised distance, the criterion used by tocher as described by rao (1952) was applied for determining the clustration group. average intra and inter cluster distances were determined using genres version 3.11, 1994 pascal intl. software and suggested by singh and chaudhary (1977). 16 3. results mean parent seed and progeny growth characters of twenty-three tested cpts of m. latifolia are presented in table 3. there is a significant difference among all seed and progenies traits. variability studies revealed that, more than twelve accessions recorded are above average for 100-seed weight (247.5±49.2), oil content (43.8±3.7) and volume index (346.0±97.7). maximum seed length (39.1 mm) was observed in cpt-15 genotype, while seed breadth (19.2 mm) was maximum in cpt–8 and cpt–9, aspect ratio (2.2) was highest in cpt-6 and cpt-15. 2d surface area (501.4 and 491.6 mm 2 ) was highest in cpt-9 and cpt-3 respectively. cpt–16 recorded the maximum for 100 seed weight (282.4 g) and oil content (51.2%). however, maximum volume index was recorded in cpt–3 (578.3 cm 3 ) followed by cpt–16 (496.0 cm 3 ). lowest seed weight (for 100 seed), oil content and volume index was expressed in genotypes cpt–4 (216.0 g) lowest oil content in cpt–21 (37.7 %) and lowest volume index in cpt–12 (176.5 cm 3 ) respectively. genotype cpt–19 and cpt–23 recorder lowest for seed length (26.8 mm), aspect ratio (1.6) and seed breadth (15.5 mm), 2d surface area (321.5 mm 2 ). table 3: mean performance of selected genotypes of madhuca latifolia for seed and progeny growth traits. genotype seed traits progeny traits seed length, mm seed breadth, mm aspect ratio 2d surface area, mm 2 100 seed weight, g oil content, % height, cm collar diameter, cm volume index, cm 3 cpt-1 33.45 bcd 16.97 efg 1.97 cde 408.48 de 235.93 ij 44.03 ghi 60.50 bcd 2.03 bcdef 253.61 cd cpt-2 31.55 def 16.75 fg 1.88 defg 385.18 efg 271.67 b 39.32 klm 54.67 d 1.99 cdef 235.94 cd cpt-3 37.99 a 18.11 bc 2.04 bc 491.57 a 264.27 bc 50.30 ab 81.17 ab 2.74 a 578.30 a cpt-4 30.45 efg 15.56 hi 1.95 cdef 355.43 fgh 216.00 l 40.38 kl 61.67 bcd 1.93 ef 235.93 cd cpt-5 34.39 bcd 17.98 cd 1.91 cdef 461.59 abc 286.27 a 49.18 bc 64.33 abcd 2.20 abcdef 310.97 bcd cpt-6 38.77 a 16.81 efg 2.21 a 478.49 ab 249.72 efgh 40.85 k 68.50 abcd 2.21 abcdef 344.32 abcd cpt-7 32.17 cdef 17.64 cde 1.82 fgh 417.48 cde 221.58 kl 40.25 kl 60.50 bcd 2.32 abcde 352.01 abcd cpt-8 33.69 bcd 19.19 a 1.75 gh 465.87 ab 260.20 cd 45.45 efg 70.67 abcd 2.58 ab 449.69 abc cpt-9 35.38 b 19.17 a 1.85 efgh 501.43 a 245.96 fgh 38.68 lm 71.83 abcd 2.28 abcde 385.56 abcd cpt-10 27.59 hi 18.18 bc 1.56 j 358.18 fgh 227.42 jk 45.92 def 60.17 bcd 2.28 abcde 335.69 bcd cpt-11 33.65 bcd 16.33 gh 2.00 bcd 400.78 def 242.31 ghi 44.05 ghi 66.17 abcd 2.35 abcde 387.45 abcd cpt-12 33.31 bcde 15.48 hi 2.12 ab 381.31 efg 257.81 cde 46.12 de 62.50 abcd 1.68 f 176.45d cpt-13 29.84 fgh 15.73 hi 1.90 cdefg 344.37 gh 254.89 cdef 47.48 cd 62.83 abcd 2.50 abcd 415.24 abcd cpt-14 32.25 cdef 18.38 abc 1.76 gh 436.97 bcd 240.18 hi 42.58 ij 72.17 abcd 2.41 abcde 423.82 abc cpt-15 39.12 a 16.94 efg 2.21 a 488.35 a 261.59 cd 41.02 jk 68.83 abcd 2.27 abcde 354.35 abcd cpt-16 32.86 bcde 18.08 bc 1.82 fgh 438.88 bcd 282.36 a 51.15 a 79.50 abc 2.53 abc 496.00 ab cpt-17 34.45 bcd 15.78 hi 2.12 ab 400.69 def 219.41 kl 39.02 lm 58.33 cd 1.97 def 251.05 cd cpt-18 32.23 cdef 16.96 efg 1.90 cdefg 407.17 de 225.96 k 43.82 ghi 55.50 d 2.08 bcdef 255.19 cd cpt-19 26.84 i 16.81 efg 1.60 ij 334.32 h 235.75 ij 45.05 efgh 64.83 abcd 2.43 abcde 379.78 abcd cpt-20 34.74 bc 17.25 def 2.02 bcd 440.61 bcd 250.25 efg 44.18 fghi 56.83 d 2.07 bcdef 268.84 bcd cpt-21 32.27 cdef 18.84 ab 1.71 hi 459.23 abc 226.55 jk 37.65 m 58.83 cd 2.00 cdef 252.19 cd cpt-22 32.26 cdef 16.66 fg 1.94 cdef 399.02 def 264.78 bc 48.05 c 70.50 abcd 2.24 abcde 356.74 abcd cpt-23 28.41 ghi 15.46 i 1.84 efgh 321.52 h 252.11 def 43.35 hi 83.67 a 2.34 abcde 458.01 abc mean 32.94 17.18 1.91 416.39 247.52 43.82 65.85 2.24 345.96 sem 0.89 0.27 0.04 14.08 3.09 0.58 8.90 0.23 98.07 cd (5%) 2.59 0.77 0.13 40.96 9.00 1.68 25.89 0.66 285.38 trait means not followed by the same superscript letter are significantly different at p = 0.05. the phenotypic and genotypic coefficients of variations are close to each other for all traits, except for volume index that exhibited striking difference between pcv (40.0%) and gcv (19.9%) indicating that for most traits, genetic control was quite high (table 4). all the seed traits showed high heritability while progeny growth characters showed low to moderate heritability. trait oil content and 100 seed weight expressed high heritability (93.5%, 93.0%) accompanied with moderate genetic divakara /journal of tropical forestry and environment vol. 4. no 02 (2014) 11-23 17 advance (17.5%, 15.6%) indicating that, heritability is due to additive gene effects and thus selection may be effective. trait volume index expressed moderate heritability (24.7%) accompanied with high genetic advance (20.4%). the low heritability is being exhibited due to high environment effects, since trait has high genetic advance, selection will be effective. similar trend was observed in casuarina equisitifolia relationship of cone and seed traits on progeny growth performance (mahadevan et al. 1999). table 4: genetic estimates of parent seed and progeny growth traits. seed traits variance coefficient of variation (%) heritability (%) ga (%) of mean genotypic phenotypic genotypic phenotypic seed length 9.17 11.54 9.19 10.31 79.5 16.89 seed breadth 1.29 1.50 6.61 7.13 85.9 12.61 aspect ratio 0.03 0.03 8.70 9.58 82.4 16.26 2d surface area 2571.64 3165.93 12.18 13.51 81.2 22.61 100 seed weight 379.11 407.76 7.87 8.16 93.0 15.63 oil content 14.24 15.24 8.61 8.91 93.5 17.15 height 25.17 143.95 7.62 18.22 17.5 6.56 collar diameter 0.03 0.11 8.22 14.93 30.3 9.33 volume index 4742.53 19168.55 19.91 40.02 24.7 20.40 of the 72 (36 genotypic and 36 phenotypic) correlations, 13 genotypic and seven phenotypic combinations were significant at 1% along with four genotypic and one phenotypic combinations was significant at 5% (table 5). skinner et al. (1999) suggested only those correlation coefficients, which are greater than 0.70 or smaller than -0.70 as biologically meaningful so that 50% of the variation in one trait is predicted by the other. the seed trait pair showing such high correlation was 11 and all were positive. at genotypic level 100 seed weight registered positive significant association with height (0.73) and oil content with volume index (0.71) at 30 mas. in the present investigation, attempts were made to assess the genetic diversity among the twenty-three cpt’s candidate plus trees based on seed and progeny traits using mahalanobis d 2 statistics. on the basis of d 2 values for all possible 253 pairs of populations, twenty-three genotypes were grouped into five clusters. cluster iii had maximum number of genotypes which is six and cluster iv and v followed accommodating five genotypes each. cluster i and ii had four and three genotypes respectively (table 6). the clustering pattern showed that geographical diversity is not necessarily related to genetic diversity. intra-cluster distance d values ranged between 5.59 in cluster ii to 9.56 in cluster v having three and five genotypes respectively (table 7). cluster v with 9.56 followed by cluster iv with 9.19 intra-cluster distance were the most diverse because the genotypes used for breeding programme were from different locations. the divergence within the cluster indicates the divergence among the genotypes in the same cluster. contrarily cluster ii showed the minimum intra genetic distance (5.59) between them revealing that these genotypes were somewhat similar in genetic 18 constitution and hybridization amongst these groups not showing sufficient variability. inter-cluster distance ranged from 8.73 between iii and v to 14.25 between ii and v (table 7). the highest intercluster distance 14.25 was followed by 13.14 between cluster i and ii. inter-cluster divergence suggests the distance (divergence) between the genotypes of different clusters. the tendency of genotypes from diverse eco-geographic regions to group together in the same cluster or scattered distributions of genotypes of same geographic origin in different clusters have been observed in the present study. table 5: correlation coefficient matrix of seed and progeny growth traits of madhuca latifolia. seed traits seed breadth aspect ratio 2d surface area 100 seed weight oil content height collar diameter volume index seed length g 0.197 0.765 ** 0.850 ** 0.329 -0.094 0.389 0.054 0.172 p 0.241 0.757 ** 0.859 ** 0.275 -0.041 0.027 0.009 0.015 seed breadth g -0.482 * 0.673 ** 0.148 0.034 0.351 0.600 0.550 ** p -0.428 * 0.683 ** 0.130 0.036 0.052 0.266 0.194 aspect ratio g 0.319 0.201 -0.106 0.055 -0.427 * -0.282 p 0.342 0.159 -0.064 -0.041 -0.205 -0.156 2d surface area g 0.323 -0.085 0.469 * 0.324 0.390 p 0.268 -0.044 0.041 0.106 0.080 100 seed weight g 0.604 ** 0.733 ** 0.405 * 0.518 ** p 0.573 ** 0.296 0.238 0.270 oil content g 0.680 ** 0.652 ** 0.705 ** p 0.273 0.328 0.330 height g 0.732 ** 0.861 ** p 0.643 ** 0.833 ** collar diameter g 0.978 ** p 0.947 ** * significant at p = 0.05, ** significant at p = 0.01 table 6: clustering of madhuca latifolia genotypes using tocher’s method. clusters number of accessions accessions (cpts) i 4 cpt-1, cpt-2, cpt-6, cpt-15 ii 3 cpt-3, cpt-5, cpt-16 iii 6 cpt-4, cpt-7, cpt-8, cpt-9, cpt-11, cpt-20 iv 5 cpt-10, cpt-12, cpt-13, cpt-14, cpt-22 v 5 cpt-17, cpt-18, cpt-19, cpt-21, cpt-23 divakara /journal of tropical forestry and environment vol. 4. no 02 (2014) 11-23 19 table 7: average intra and inter-cluster distance and d 2 values. * clusters i ii iii iv v i 8.056 (64.906) 13.144 (172.769) 9.092 (82.669) 11.406 (130.104) 10.394 (108.041) ii 5.591 (31.255) 12.674 (160.618) 10.322 (106.540) 14.247 (202.974) iii 8.702 (75.725) 9.739 (94.845) 8.725 (76.128) iv 9.192 (84.499) 10.079 (101.582) v 9.559 (91.366) * figures given in the parenthesis are d 2 values. table 8: cluster wise mean values of six seed traits and three progeny traits. traits\clusters i ii iii iv v percent contribution seed length (cm) 35.7 35.1 33.4 31.1 30.8 5.1 seed breadth (cm) 16.9 18.1 17.5 16.9 16.8 11.1 aspect ratio 2.1 1.9 1.9 1.9 1.8 0.0 2d surface area (mm 2 ) 440.1 464.0 430.3 384.0 384.6 0.0 100 seed weight (g) 254.7 277.6 239.4 249.0 232.0 19.8 oil content (%) 41.3 50.2 42.2 46.0 41.8 19.4 plant height (cm) 63.1 75.0 64.6 65.6 64.3 4.0 collar diameter (cm) 2.1 2.5 2.3 2.2 2.2 7.1 volume index (cm 3 ) 297.1 461.8 346.6 341.6 319.2 33.6 cluster means indicated a wide range of variation for all the seed and progeny traits (table 8). the best cluster for seed breadth of 18.1 mm, 2d surface area of 464.0 mm 2 , 100 seed weight of 277.6 g, oil content of 50.2%, plant height of 75 cm, collar diameter of 2.5 cm and volume index of 461.8 cm 3 was for cluster ii. maximum seed length (35.7 mm) and aspect ratio (2.1) was recorded by cluster i. cluster v recorded minimum for seed length (30.8 mm), seed breadth (16.8 mm) and aspect ratio (1.8) and 100 seed weight (232.0 g) while cluster i recorded minimum for oil content (41.3%), plant height (63.1 cm) collar diameter (2.1 cm) and volume index (297.1 cm 3 ). cluster ii has genotype (cpt–3, cpt–5 , cpt–16) containing high volume index (578.3 cm 3 ), 100 seed weight (286.3 g), oil content (51.2%) and cluster i has genotype (cpt-15) containing high seed length (39.1 mm) and aspect ratio (2.2). thus it may be suggested that crosses involving under cluster ii and i may result in substantial segregates and further selection for overall improvement of the species. 4. discussion seed weight, depends on reserve food material, which is produced as a result of double fertilization (endosperm) and is dominated by the maternal traits and is also influenced by the nutrient availability at the time of seed setting and environmental factors (allen, 1960; johnsen et al., 1989). embryo development and its physiological function are contributed by the maternal as well as by paternal (pollen grain) traits in the species. the occurrence of m. latifolia over a wide range of habitats with diverse geo-climatic conditions was expected to be reflected in the genetic constitution of its 20 populations. in the present study, the seeds from various cpts exhibited significant seed trait variability (table 3) which could be attributed to population isolations that inturn influence gene flow. significant variability of seed characters like; seed size and weight was observed in seeds of the selected plus trees (bagchi and sharma, 1989) and among various provenances of santalum album (veerendra et al., 1999). genetic control of seed size traits has been observed in several tree species (loha et al., 2006). though the selection of superior trees was carried out intensively and clonal superiority over seed raised plants was established (kumar, 1995), genetic superiority per se needs to be determined. genetic estimates could considerd as useful tools in predicting the amount of gain expected in short period of time. the variation among genotypes is commonly used as an estimate of total genetic variation and to calculate the degree of genetic control for a particular trait (foster and shaw, 1988). marginal difference between pcv and gcv and high estimates of heritability for all pod and seed traits studied revealed the presence of heritable nature in variability (table 4). the magnitude of the error variance was relatively lower than the genotypic variance for all traits except for height, collar diameter and volume index (data not given). higher magnitude of genotypic variance over error variance on one hand and close values of phenotypic and genotypic variances on the other hand for all the seed traits, indicated considerable scope for selection. relatively high value of genotypic variance that resulted in high estimates of heritability which contributed to the high genetic gains expected in oil content. gains from tree breeding programs depend on the type and extent of genetic variability. in the present study the genotypic coefficient of variation and the genetic gain were found to be comparatively higher for an important trait such as volume index, 100-seed weight and oil content. the high estimates of heritability combined with high genetic advance suggests that population means for volume index may be changed considerably by selecting the superior 5% of the genotypes. high heritability for growth parameters have been reported in tectona grandis (gera et al., 2001) and accompanied by high genetic advance in prosopis cineraria (solanki et al., 1984). as variation among genotypes is used for estimation of genetic variation and genetic gain, covariance estimates between traits can be used to estimate genetic correlations between the traits (foster, 1986). in genetic improvement of m. latifolia clear understanding of the relationships among different seed and progeny traits is very essential. correlation establishes the extent and cause of association between seed traits and its attributes so that these components may form additional criteria for selection in breeding program. correlated quantitative traits are of a major interest in an improvement program, as the improvement of one character may cause simultaneous changes in the other character. similar correlation trend was seen in jatropha curcas (kaushik et al., 2007a) and pongamia pinnata (kaushik et al., 2007b) seed traits. hence 100 seed weight may be included among the criteria for selection of plus trees. the genotypic correlation is an estimated value, whereas, phenotypic correlation is a derived value from the genotype and environmental interaction (chaturvedi and pandey 2004). the genotypic correlation is, therefore, a more reliable estimate for examining the degree of relationship between character pairs. the present study indicates the correlation of 100 seed weight and oil content to growth of m. latifolia at juvenile stage. positive correlation between seed weight and seedling height in pinus spp. has been observed but it disappeared with the growing age of the seedlings (righter, 1945). however correlation between seed weight and height till 15 years was observed in pinus taeda (robinson and van buijtenen, 1979). khalil (1981) stated that, significant positive correlation and regression between 1,000 seed weight and height at four years in picea glauca which is not mere carryover of the initial effect in the first year growth but appears to be genetically correlated and recommended that seed weight may be included among the criteria for selection of plus trees. divakara /journal of tropical forestry and environment vol. 4. no 02 (2014) 11-23 21 genetic diversity in plant species is a gift to mankind as it forms the basis for selection and further improvement. in jatropha curcas kaushik et al. (2007a) attempted to analyse the diversity among the 24 cpt’s from haryana of india. in the present study clustering pattern showed that geographical diversity is not necessarily related to genetic diversity (table 6). in rice it is reported that this kind of genetic diversity might be due to differential adoption, selection criteria, selection pressure and environment (vivekananda and subramanian, 1993). this indicated that genetic drift produces greater diversity than the geographic diversity (singh et al., 1996). absence of any relationship between genetic diversity and geographical distribution is in accordance with the findings of kaushik et al. (2007a) and gohil and pandya, (2008) in j. curcas. the contribution of individual characters to the diversity has been studied. the trait volume index contributed maximum for 33.6% for genetic diversity and rank total of 85. the character contributing maximum diversity can be given more emphasis for the purpose of fixing priority of parents in hybridization program. cluster v and cluster iv with high intra-cluster distance were the most diverse and the divergence within the cluster indicates the divergence among the genotypes in the same cluster (table 7). hence, best suited for within group is the hybridisation. cluster means indicated crosses involving under cluster ii and v and cluster ii and i may result in substantial segregates and further selection for overall improvement of species. in general, the cluster ii and i, v exhibited high and low mean values respectively for most of the characters (table 8). it is also suggested that for creating variability and developing the best selection a large number of divergent lines, instead of few should be used in the hybridization. earlier studies, in crop plant had indicated that inter-mating of divergent groups would lead to greater opportunity for crossing over which would release latent variation by breaking up predominantly repulsion linkage (thoday, 1960) and utilization of diverse parents in breeding was also stressed by (singh et al., 1981). 5. conclusions cpt-3, cpt-5 and cpt-16 found to be superior for volume index, 100 seed weight and oil content respectively; hence seeds of these cpt may be given importance for massive afforestation programme. the traits 100 seed weight and oil content were highly correlated with growth (volume index) of the tree. in addition, seed breadth expressed correlation with volume index. hence identification of good cpts may be graded based on seed weight and/or size and/or shape is advantageous. since traits viz. 100 seed weight and oil content are under strong genetic control, improvement in these characters can bring improvement in volume index. the divergence among the genotypes in cluster v and cluster iv as indicated by intra-cluster distance can be best used for within group hybridization. inter-cluster distance suggested that crosses involving under cluster ii & v and cluster ii and i may result in substantial segregates and further selection for overall improvement of the species. as tree improvement is a continuous programme, progenies of all cpts will further be evaluated for total yield and oil content in future to check the pattern of character association and selection of elite material. the present study can however serve as a pointer to be compared with the results to be obtained at later stages especially seed and oil yield and also to establish the correlations. this study would perspectively determine whether genetic analysis at early stage is reliable. if reliable, genetic assessment for other population can also be carried out with suitable correlation factors the extent of relationship can be determined acknowledgements the author is grateful to national bank for agriculture and rural development (nabard), mumbai for financial assistance in the form of research and development grants and the director, 22 institute of forest productivity (icfre), ranchi for providing the necessary facilities. sincere thanks are due to ccf (research) and field staff of jharkhand forest department for their cooperation in survey and identification and collection of clones. reference allard, r.w. 1999. principles of plant breeding, (2 nd edition) john wiley & sons, ny, pp.254. allen, g.s. 1960. factors affecting the viability and germination behaviour of coniferous seed. iv. stratification period and incubation temperature, pseudostuga menziesii (mirb.) franco. forestry chronicle, 36: 18-19. bagchi, s.k. and sharma, v.p. 1989. biometrical studies on seed characters of santalum album l. silvae genet, 38: 152-153. burton, g.w. 1952. quantitative inheritance of grass. proceedings of 6 th international grassland congress held at pennsylvania state college. pa. u.s., 1: 74-83. chaturvedi, o.p. and pandey, n. 2004. correlation and path analysis studies between biomass and other characters in bombax ceiba l. silvae genetica, 53: 5-6. csir. 1998. wealth of india: a dictionary of indian raw material and industrial products. vol. vi (lm) council of scientific and industrial products, new delhi, pp. 207-216. foster, g.s. 1986. provenance variation of eastern cottonwood in the lower mississippi valley. silvae genet, 35: 32-38. foster, g.s. and shaw, d.v. 1988. using clonal replicates to explore genetic variation in a perennial plant species. theor. appl. genet, 76: 788-794. gera, m., gera, n. and sharma, s. 2001. estimation of variability in growth characters of forty clones of tectona grandis. indian forester, 127: 639–43. gohil, r.h. and pandya, j.b. 2008. genetic diversity assessment in physic nut (jatropha curcas l.) international journal of plant production, 2(4): 321-326. gomez, a.k. and gomez, a.a. 1984. statistical procedure for agricultural research. john wiley and sons, inc. goulden, c.h. 1952. some distance properties of latent root and vector methods used in multivariate analysis. biometrica, 53: 325-338. hill, j., nelson, e. and tilman, d. 2006. environmental, economic and energetic costs and benefits of biodiesel and ethanol biofuels. proceedings of national academic of science, usa, 103: 11206–11210. johanson, h.w., robinson, h.f. and comstock, r.e. 1955. estimate of genetic and environmental variability in soyabeans. agron. j, 47: 314-318. johnsen, o., dietrichson, j. and skaret, g. 1989. phenotypic changes in progenies of northern clones of picea abies (l.) karst. grown in a southern seed orchard. iii. climate changes and growth in a progeny trial. scand. j. for. res, 4: 343–350. kaushik, n., kumar, k., kumar, s., kaushik, n. and roy, s. 2007a. genetic variability and divergence studies in seed traits and oil content of jatropha (jatropha curcas l.) accessions. biomass bioenergy, 31: 497-502. kaushik, n., kumar, s., kumar, k., beniwal, r. s., kaushik, n. and roy, s. 2007b. genetic variability and association studies in pod and seed traits of pongamia pinnata (l.) pierre in haryana, india. genet resour crop evol, 54: 1827-1832. khalil, m.a.k. 1981. correlation of juvenile height growth with cone morphology and seed weight in white spruce. silvae genetica, 30(6): 179-181. divakara /journal of tropical forestry and environment vol. 4. no 02 (2014) 11-23 23 kumar, a. 1995. genetic improvement of casuarina equisetifolia. phd thesis, forest research institute (deemed university), dehra dun, india. loha, a., tigabu, m., teketay, d., lundkvist, k. and fries, a. 2006. provenance variation in seed morphometric traits, germination and seedling growth of cordia africana lam. new forests, 32: 71-86. mahadevan, n.p., sivakumar, v. and gurudev singh, b. 1999. relationship of cone and seed traits on progeny growth performance in casuarina equisetifolia forst. & forst. silvae. genet, 48(6): 273-277. mahalonobis, p.c. 1936. on the generalized distance in statistics. proceeding of national institute of sciences, india, 2: 49-55. manavalan, a. 1990. seedlind vigour and bioproductivity in woody biomass species. ph.d. thesis, madurai kamaraj university, madurai, india. rao, c.r. 1952. advanced statistical methods in biomatrics research. john wiley and sons, inc., newyork, 260pp. righter, f.i. 1945. pinus: the relationship of seed size and seedling size to inherent vigor. journal of forestry, 43: 131-137. robinson, j.f. and van buijtenen, j.p. 1979. correlation of seed weight and nursery bed traits with 5, 10 and 15 year volume in loblolly pine progeny test. forest science, 35(4): 591-596. singh, a.k., singh, s.b. and singh, s.m. 1996. genetic divergence in scented and fine genotypes of rice (oryza sativa l.) ann agric res, 17: 163-166. singh, r.k. and chaudhary, b.d. 1977. biometrical methods in quantitative genetic analysis. kalyani publication, new delhi, pp.596. singh, y.p., kumar, a. and chauhan, b.p.s. 1981. genetic divergence in pearl millet. indian journal of genetics, 41: 186-190. skinner, d.z., bauchan, g.r., auricht, g. and hughes, s. 1999. a method for the efficient management and utilization of large germplasm collections. crop science, 39: 1237-1242. solanki, k.r., muthana, k.d., jindal, s.k. and arora, g.d. 1984. variability, heritability and correlation for growth parameters in prosopis cineraria. journal of tree science, 3: 86-8. thoday, j.m. 1960. effect of disruptive selection. iii. coupling and repulsion. heredity, 14: 35-49. veerendra, h.c.s., ramalakshmi, s. and mallesha, b.b. 1999. variation in seed characterstics in provenances of sandal (santalum album l.). indian forester, 125: 308-312. vivekananda, p. and subramaninan, s. 1993. genetic divergence in rainfed rice. oryza, 39: 60-62. qasim /journal of tropical forestry and environment vol. 7, no. 02 (2017) 121-127 121 forest carbon stock assessment of the musk deer national park, azad jammu andkashmir (ajk) m. qasim national forest inventory expert, national redd+ office, ministry of climate change, government of pakistan, adventure foundation complex, garden avenue, islamabad, pakistan. date received: 08-09-2017 date accepted: 21-12-2017 abstract in order to tackle with the increasing challenges of climate change, forests are considered as a viable option. schemes such as reduced emissions from deforestation and forest degradation plus (redd+) are regarded as financial ventures for not only tackling climate change but also conserving forestry resources and for alleviating poverty. such schemes however require the exercise of forest carbon stock assessments. it is therefore essential to understand the dynamics of carbon stocks in various forest ecosystems. the study therefore was conducted to assess the carbon stocks of the forests of musk deer national park, ajk. standard methods were used to calculate the carbon stocks of the musk deer national park. the results revealed that the sampled area of the park contained mean carbon stocks per hectare (ha) of 44.64±12.44 mg ha-1. the piceasmithianawith 25.40±14.53 mg ha-1 had the highest of the mean carbon stocks per ha followed by abiespindrowwhich had the mean carbon stocks per ha of 17.77±11.80 mg ha-1. the study was the first attempt, to the extent of my knowledge, for forest carbon stock assessment of the musk deer national park. the results can be helpful in developing redd+ projects in future, which can assist in forest resource conservation and poverty alleviation. 1. introduction the adverse impacts of climate change are becoming quite evident, which can also be observed if we observe the global events(houghton et al., 2009). the brunt of which is mainly being faced by the developing countries. the developing countries do not have the resources and technology to cope with the hazards of climate change. forests however are considered to be the cheapest option for tackling climate change(tobin and nieuwenhuis, 2007). most of the global population, but, residing in the developing countries is highly relying on the forests. forests thereby deliver various tangible and intangible benefits to the wider societies(paquette and messier, 2010). unfortunately despite manifold benefits associated with forests, they are still not accounted for in policies of many developing countries, further augmenting the problems of deforestation and forest degradation. reduced emissions fromdeforestation and forest degradation plus (redd+), regarded as a financial mechanism, is focused upon reducing carbon emissions from deforestation and forest degradation, aimedtowards the conservation and enhancement of forest carbon stocks, and sustainable forestmanagement which includes ecological and social targets (bluffstone et al., 2013). *correspondence: mohammadqasimkhan@yahoo.com tel: issn 2235-9370 print / issn 2235-9362 online © university of sri jayewardenepura mailto:mohammadqasimkhan@yahoo.com 122 it has been considered as one of the viable options for not just tackling climate change but also conserving unique forestry resources along with alleviating poverty(ngo et al., 2013). due to the above mentioned, it has also been identified as one of the most economically feasible mitigation options (stern, 2007). for redd+ initiatives, however, forest carbon stock assessments and monitoring is essential. it is thus important that carbon stock assessments of various forest types should be conducted. in view of the above, a study was conducted in musk deer national park. the main objective of the study was the carbon stock assessment of the forests of the musk deer national park. thereby for this purpose, the carbon stocksin aboveground biomass of the trees of the musk deer national parkwere estimated. 2. materials and methods 2.1 study area the musk deer national park, gurez, is located in district neelum of azad jammu andkashmir (ajk). the park is spread over an area of 52,817 hectares. the altitudinal range is between 2,107 m to 4,345 m. it was established by the government of ajk in 2007, mainly for the conservation of himalayan musk deer (moschuschrysogaster; qureshi et al., 2013). the park is mostly comprised of moist temperate forests, except for the sub-alpine forests which lies between 3352 m to 3657 m (qureshi et al., 2013). the park is comprised of 19 villages, relying heavily on the natural resources of the park(jalil et al., 2016). 2.2 data collection and analysis overall 24 circular plots were sampled. the circular plots were with 20 m radius. the random sampling approach was adopted with laying of plots(qasim et al., 2016b). in each plot, diameters at breast height (dbh) of trees with dbh above then 5 cm were measured. the dbh were measured with the help of a diameter tape at 1.3 m above the ground level (qasima et al., 2016). the height of the trees was measured with the blumeleiss hypsometer(qasima et al., 2016). the observed slopes were adjusted following (sharma et al., 2011). the tree volume for each was measured with the help of following formula1adopted from (philip, 1994); 𝑉𝑜𝑙𝑢𝑚𝑒 (𝑚3) = (𝜋/4) 𝐷𝐵𝐻2 𝑥 ℎ 𝑥 𝑓 (1) where: h= tree height f= form factor the form factors were sourced from available literature(masota et al., 2014). the stem biomass was further calculated using following formula 2. 𝑆𝑡𝑒𝑚 𝐵𝑖𝑜𝑚𝑎𝑠𝑠 (𝑘𝑔) = 𝑉𝑜𝑙𝑢𝑚𝑒 𝑥 𝑊𝐷 (2) where: wd = basic wood density the wd (kg m3) for the trees species were sourced from available literature (sharma et al., 2016). the total biomass was calculated using biomass expansion factor (bef). the bef were taken from the available literature(alam and nizami, 2014;haripriya, 2000). the total biomass was converted into carbon stocks by using a conversion factor of 0.5 (tan et al., 2010). the density was taken as the total number of trees per hectare (ha). the basal area was calculated following (qasim et al., 2016). qasim /journal of tropical forestry and environment vol. 7, no. 02 (2017) 121-127 123 2.3 statistical analysis the normal distributions of different variables were tested using the shapiro-wilk test. the means±standard deviations (sd) for averages of different variables were calculated. the kruskal wallis rank sum test was used for exploring differences between more thantwo variables. the post-hoc analysis for significant differences between means of different variables was done using tukey’s test.a significance level of 0.05 was used for all the statistical tests. the version 3.1.0 of rwas used for statistical analysis and for producing graphs. 3. results the highest mean carbon per hawas recorded for piceasmithiana which was 25.40±14.53 mg ha1. the abiespindrow recorded the second highest mean carbon per ha, which was 17.77±11.80mg ha-1. the betulautilis and acer ceasium recorded mean carbon per ha of 1.00±0.84mg ha-1 and 0.45±0.06mg ha-1respectively (table 1). the highest mean biomass was recorded for the piceasmitheana which was 5.23±2.99 mg. it was followed by abiespindrow, which showed mean biomass of 3.66±2.43 mg (table 1). similarly, the highest mean volume was recorded for piceasmithiana with 7.53±4.30 m3.the lowest mean volume on the other hand was recorded for acer ceasium, which was 0.08±0.01 m3 (table 1). the highest mean basal area per ha was recorded for piceasmithiana, with 7.17±3.98m2ha-1 and it was followed by abiespindrowwith5.58±3.20m2ha-1 (table 1). the highest mean dbh was also recorded for piceasmithiana, with 97.01±4.95 cm and the lowest dbh was recorded for acer ceasium with 19.01±1 cm (table 1). the highest mean density per ha was recorded for betulautilisas92.98±57.02 trees ha-1, which was followed by abiespindrow, with 72.45±41.11 trees ha-1 (table 1). table 1: structural characteristics of the forests of musk deer national park. no. tree species mean density (trees ha-1) mean dbh (cm) mean height (ft) mean basal area (m2 ha-1) mean volume (m3) mean biomass (mg) mean carbon (mg ha-1) 1 abiespindrow 72.45 ± 41.11 85.57 ± 30.57 52.91 ± 13.01 5.58 ± 3.20 5.04 ± 3.35 3.66 ± 2.43 17.77 ± 11.80a 2 piceasmithiana 32.38 ± 21.17 97.01 ± 4.95 61.66 ± 15.41 7.17 ± 3.98 7.53 ± 4.30 5.23 ± 2.99 25.40 ± 14.53a 3 betulautilis 92.98 ± 57.02 24.46 ± 9.7 25.02 ± 5.63 0.45 ± 0.31 0.19 ± 0.16 0.20 ± 0.17 1.00 ± 0.84b 4 acer ceasium 48.57 ±1.58 19.01 ± 1 20 ±0.70 0.27 ±0.02 0.08 ±0.01 0.09 ±0.01 0.45±0.06b overall 44.64± 12.44 the mean carbon (mg ha-1) for the species not sharing common lower case differ significantly not sharing a common (p<0.05) based on tukey’s test. the total mean carbon stocks per ha for the sampled area of the forests of musk deer national park was recorded as 44.64±12.44mg ha-1. the highest mean carbon stock was measured for plot 8, which was 7.46 mg ha-1. the lowest was recorded for plot 11, which was 0.11 mg ha-1 (figure 1). the maximum mean dbh of 95.28 cm was recorded for plot 8 and the minimum mean dbh of 19.35 cm was recorded for plot 11. the highest mean height of 55 feet (ft) was recorded for plot 13 and the lowest mean height of 25 ft was recorded for plot 11. significant differences were recorded between the mean carbon stock of the four trees species, abiespindrow, piceasmithiana, betulautilis and acer ceasium(p<0.05; wilcoxon test). the significant differences between the mean carbonswere recorded between 124 betulautilis-abiespindrow, betulautilis-piceasmithiana, acerceasium-abiespindrowandacer ceasiumpiceasmithiana(p<0.05; tukey’s test; table 1). figure 1: carbon stocks at musk deer national park. the dbh distribution of the forests of musk deer national park has displayed an inverted j (figure 2). most of the trees have been recorded in the lower dbh classes comparing to the highest dbh classes (figure 2). for the height distribution, most of the trees were recorded for lower dbh classes (figure 3). figure 2: dbh distribution of the forests of the musk deer national park. qasim /journal of tropical forestry and environment vol. 7, no. 02 (2017) 121-127 125 figure 3: height distribution of forest of musk deer national park. 3. discussion results from this study for the mean carbon stocks of spruce smithiana and abiespindrow are close to the results of a. ahmad et al.(2014). the mean densities of spruce smithiana and abiespindrowfrom our study are also close to the results of a. ahmad et al.(2014). the result from this study for mean carbon stocks of moist temperate forests is in correspondence with kumar and sharma(2015). the results from this study for mean carbon stocks of temperate forests is also close to sharma et al. (2011). the mean volume of piceasmithiana. from this study, was close to the mean volume of the same species reported by ahmad et al. (2014). the volume of betulautilisfrom this study is close to the volume reported by alam and nizami(2014). the result for carbon stocks for betulautilisfor this study is not in correspondence with alam and nizami(2014). this could be attributed to the quality of the site(cummings et al., 2002). the dbh distributions provide the spatial relationship between the trees and their environment. these are widely adopted for extrapolating forest structures(burgess et al., 2005). the dbh distributions can help forest managers in relating of various parameters such as age and density (schreuder and swank, 1974). growth and yield predictions are often widely based on dbh distributions(zeide, 1989). the dbh distribution of the forests of musk deer national park followed aninverted j shape. the trees were found to be mostly in the lower dbh classes, which infers good recruitment and reproduction(gebrehiwot and hundera, 2014). such dbh distribution pattern was also reported by siddiqui et al.(2013)in other mountainous areas of pakistan. tree height is also considered as one of the most important variables in forest management (gómez-garcía et al., 2014). tree height is essential because it helps in characterizing the forest stand structures, for estimation of single tree volume and forest stand volumes, and for determining dominant heights and site index of forests (peng et al., 2001). the lowest mean height was recorded for betulautilis, 15 ft, in the musk deer national park and the highest mean heights were recorded for piceasmithiana and abiespindrow, which were 80 ft each. 126 4. conclusions the mean carbon stocks per ha for the sampled area of the forests of the musk deer national park was recorded as 44.64±12.44 mg ha-1. significant differences were recorded between the mean carbon stocks per ha of all four trees species abiespindrow, piceasmithiana, betulautilis and acer ceasium. the dbh distribution of the sampled plots have shown an inverted j, where most of the trees have been recorded in the lower dbh classes. the height distribution has also displayed higher occurrence of trees in lower dbh classes. the study was the first attempt, to the extent of my knowledge, for quantifying the carbon stocks of the forests of the musk deer national park. studies such as this can be helpful in developing forest carbon stock tables which can be included in the forest management plans of the national park. moreover, the data can also be helpful for developing redd+ projects in the future, which can support the cause of conservation of the forest resources but as well as the poverty alleviation in the area. references ahmad, a., mirza, s.n., nizami, s., 2014. assessment of biomass and carbon stocks in coniferous forest of dir kohistan, kpk. pak j agric sci 51, 35–350. ahmad, s., ahmad, a., moazzam, n., 2014. assessment of biomass expansion factor of picea smithiana (wa-ll) boiss. int. j. sci. eng. res. 5, 1232–1239. alam, k., nizami, s.m., 2014. assessing biomass expansion factor of birch tree betula utilis d. don. open j. for. 4, 181. bluffstone, r., robinson, e., guthiga, p., 2013. redd+and community-controlled forests in low-income countries: any hope for a linkage? ecol. econ. 87, 43–52. doi:10.1016/j.ecolecon.2012.12.004 burgess, d., robinson, c., wetzel, s., 2005. eastern white pine response to release 30 years after partial harvesting in pine mixedwood forests. for. ecol. manag. 209, 117–129. cummings, d., kauffman, j.b., perry, d.a., hughes, r.f., 2002. aboveground biomass and structure of rainforests in the southwestern brazilian amazon. for. ecol. manag. 163, 293–307. gebrehiwot, k., hundera, k., 2014. species composition, plant community structure and natural regeneration status of belete moist evergreen montane forest, oromia regional state, southwestern ethiopia. momona ethiop. j. sci. 6, 97–101. gómez-garcía, e., diéguez-aranda, u., castedo-dorado, f., crecente-campo, f., 2014. a comparison of model forms for the development of height-diameter relationships in even-aged stands. for. sci. 60, 560–568. houghton, r., hall, f., goetz, s.j., 2009. importance of biomass in the global carbon cycle. j. geophys. res. biogeosciences 114. jalil, a., khan, k., arshad, m., yiping, l., 2016. socio-economic impact on natural resources in musk deer national park (mdnp)-guraiz valley, district neelum, azad kashmir, pakistan. science, technology and development 35, 110–116. doi:10.3923/std.2016.110.116 kumar, a., sharma, m., 2015. estimation of carbon stocks of balganga reserved forest, uttarakhand, india. for. sci. technol. 11, 177–181. masota, a.m., zahabu, e., malimbwi, r.e., bollandsås, o.m., eid, t.h., 2014. volume models for single trees in tropical rainforests in tanzania. journal of energy and natural resources 3, 66–76. doi:10.11648/j.jenr.20140305.12 ngo, k.m., turner, b.l., muller-landau, h.c., davies, s.j., larjavaara, m., bin nik hassan, n.f., lum, s., 2013. carbon stocks in primary and secondary tropical forests in singapore. for. ecol. manag. 296, 81–89. paquette, a., messier, c., 2010. the role of plantations in managing the world’s forests in the anthropocene. front. ecol. environ. 8, 27–34. qasim /journal of tropical forestry and environment vol. 7, no. 02 (2017) 121-127 127 peng, c., zhang, l., liu, j., 2001. developing and validating nonlinear height–diameter models for major tree species of ontario’s boreal forests. north. j. appl. for. 18, 87–94. philip, m.s., 1994. measuring trees and forests. cab international, wallingford. qasim, m., porembski, s., sattler, d., stein, k., thiombiano, a., lindner, a., 2016a. vegetation structure and carbon stocks of two protected areas within the south-sudanian savannas of burkina faso. environments 3, 25. qasim, m., porembski, s., stein, k., lindner, a., 2016b. rapid assessment of key structural elements of different vegetation types of west african savannas in burkina faso. j. landsc. ecol. 9, 36– 48. qureshi, b., anwar, m., hussain, i., beg, m., 2013. habitat utilization of himalayan musk deer (moschus chrysogaster) in the musk deer national park guraiz, azad jammu and kashmir, pakistan. j. anim. plant sci. 23, 1366–1369. schreuder, h.t., swank, w.t., 1974. coniferous stands characterized with the weibull distribution. can. j. for. res. 4, 518–523. sharma, c., gairola, s., baduni, n., ghildiyal, s., suyal, s., 2011. variation in carbon stocks on different slope aspects in seven major forest types of temperate region of garhwal himalaya, india. j. biosci. 36, 701–708. sharma, c., mishra, a.k., krishan, r., tiwari, o., rana, y., 2016. variation in vegetation composition, biomass production, and carbon storage in ridge top forests of high mountains of garhwal himalaya. j. sustain. for. 35, 119–132. siddiqui, m.f., ahmed, m., shaukat, s.s., khan, i.a., sarangzai, a.m., khan, n., 2013. present status and size class structure of some conifer dominating forests from moist temperate area of western himalayan and hindukush region of pakistan. fuuast j. biol. 3, 141. stern, n., 2007. climate. stern review: the economics of climate change. universit y press, cambridge. tan, z., zhang, y., yu, g., sha, l., tang, j., deng, x., song, q., 2010. carbon balance of a primary tropical seasonal rain forest. j. geophys. res. atmospheres 115. tobin, b., nieuwenhuis, m., 2007. biomass expansion factors for sitka spruce (picea sitchensis (bong.) carr.) in ireland. eur. j. for. res. 126, 189–196. zeide, b., 1989. accuracy of equations describing diameter growth. can. j. for. res. 19, 1283–1286. issn 2235-9370 print / issn 2235-9362 online © university of sri jayewardenepura karunarathne and gunawardena/ journal of tropical forestry and environment vol. 10 no. 01 (2020) 51-62 _____________________________________________ *correspondence: prasanth@sjp.ac.lk tel: +94 714166159 © university of sri jayewardenepura 51 economic value of urban green space: a travel cost approach for viharamahadevi urban park, sri lanka h.m.l.p. karunarathne 1 and u.a.d.p. gunawardena2* 1 department of estate management and valuation, university of sri jayewardenepura, nugegoda, sri lanka 2 department of forestry and environmental science, university of sri jayewardenepura, nugegoda, sri lanka date received: 10-05-2020 date accepted: 25-06-2020 abstract urban green spaces could bring cities and their inhabitants with vitality in terms of ecological, social, and economic benefits. recognising and estimation of economic values of parks is important for their sound management and for justification of the current use over various alternative uses. non recognition of values of the services of such green spaces may lead to unsound management and degradation resulting in depriving urban communities of those benefits. viharamahadevi urban park is the oldest and largest park in colombo which offers recreation and green space to the inhabitants and visitors of the city. the purpose of this study is to estimate the recreational value of the park using individual travel cost method (itcm). visitors of viharamahadevi urban park selected using purposive sampling method were interviewed with a structured questionnaire. data on visitation frequencies, preferences for park characteristics and socio economic parameters were collected using face-to-face interviews. in order to cater for the data issues of the itcm, a zero truncated negative binomial regression analysis was performed in estimating the demand function. results indicate that household income and the enjoyment of the visitors significantly and positively determine the number of visits made by the people. the annual social welfare generated from the recreational value of the viharamahadevi park is lkr 55.7 billion. the estimated value will be able to provide significant guidance towards future park management decisions. keywords: individual travel cost method, viharamahadevi park, recreation values, urban green space 1. introduction urban green spaces could insert cities with vitality in terms of ecological, social, and economic benefits. research indicate that having urban green spaces may largely mitigate social problems in the urban areas and provide an attractive environment to residents, lessen urban heat island effect, act as carbon sink, increase the access to shade, improve water penetration, protect bio-diversity, and eventually improving well-being of people (ulrich et al., 1991; zhou and rana, 2012; rakhshandehroo et al., 2017). further, green spaces increase the economic value of spaces, reduces the social gap in the community and ensures socio-environmental sustainability (chen and jim, 2008; zhou and rana, 2012). conserving urban green spaces in the city is therefore an important strategy to maintain sustainability (social, environmental and economic) and it is a major responsibility of municipalities to play a great role in preserving, improving, and maintaining parks in urban areas. doi: https://doi.org/10.31357/jtfe.v10i1.4688 52 accordingly, economic valuation of parks can be considered as a valuable source of information not only for the municipalities but for the society in general for a sound management of parks and to understand the services provided by these parks. moreover, economic efficiency in resource management requires knowledge of the flow of park benefits and costs. the non-recognition of the value of services of ecosystems/ parksmay result in degrading and unsound management of such resources and finally depriving people the full use of the services of these ecosystems. hence, it is important to identify the recreational values for the sound management of these parks. in that context, valuation can be used to measure the benefits derived from the park (mathieu et al., 2003; alvarez and larkin, 2008). accordingly, this study intends to determine the recreational value of viharamahadevi urban park, colombo, sri lanka. however, ascertainment of value is a complex task in the absence of market values. in order to value recreational benefits of public parks, different types of valuation approaches can be employed. the present study has employed individual travel cost method (itcm). accordingly, individuals‟ willingness to pay for a visit to a site can be estimated based on the number of trips they make at different travel costs (twerefou and ababio, 2012). this method is one of the most appropriate means of determining the recreational value of non-market goods like forests and parks. the unique advantage of tcm compared to other valuation approaches is that, the method is based on actual behaviour. applications of tcm to value recreational resources is abundant in sri lanka for wild life parks (rathnayake and gunawardena, 2002; rathnayake and gunawardena, 2011) viewing leopards (wickramarachchi and gunawardena, 2012), botanical gardens (jayaratne and gunawardena, 2004 and madhuwanthika and gunawardena, 2017) and for urban recreational sites (marawila and thibbotuwawa, 2010). this research enhances the knowledge on environmental valuation in the urban park context. the rest of the paper is organized as follows: the next section provides an overview on benefits and economic values of urban parks which is followed by study methodology, results, discussion, conclusion and policy implications. 2. urban parks and their values urban green space can be recognised as an integrated area comprising natural, semi-natural, or artificial green lands which supply benefits to different groups of people within the city (tzoulas et al., 2007; zhou and rana, 2012). it can be further defined as “an open space situated within the city limits with a good vegetation cover planted deliberately or inherited from pre-urbanisation vegetation and left by design or by default” (jim and chen, 2006). urban green space consists with urban forest as well as other green areas for example, public parks, edges of roads, sport fields, public or private gardens, and remnant patches of natural vegetation as well as individual street trees (davies et al., 2008; wu, 2008; zhou and rana, 2012). some researchers also have used the term “green infrastructure” to consider the urban green space as a coherent planning entity (ahem, 2007; zhou and rana, 2012). research shows that the availability of urban green space may largely mitigate social problems in the urban context and provide a beautiful and healthy environment to residents (ulrich et al., 1991; zhou and rana, 2012). urban green space can bring ecological, social, and economic benefits to people resulting in a better quality of life for people (smith et al., 2005; barbosa et al., 2007; jorgensen et al., 2002; ulrich et al., 1991; takano et al., 2002; jackson, 2003; givoni, 1991; heidt and neef, 2008; zhou and rana, 2012; chen and jim, 2008). therefore, it is vital to maintain green spaces in the urban areas. one of the most important reasons for the vulnerability of urban green space is that the value of green space is not directly expressed in monetary terms. as a result, the planners and policy makers cannot clearly understand the values of different land covers, and the decision-making process cannot be karunarathne and gunawardena/ journal of tropical forestry and environment vol. 10 no. 01 (2020) 51-62 53 effectively facilitated. although benefits of green space cannot be fully measured in a monetary terms, this valuation process can at least provide more weight to green space when making tradeoffs between the green land cover and others (luttik, 2000; zhou and rana, 2012). in other words, valuation gives clear way to explain the extent to which green space benefits people in monetary terms. 2.1 valuation of benefits of urban recreational resources several environmental valuation techniques have been developed to measure the economic value of non-marketed environmental goods such as national parks, geo-forest parks, beach, which include travel cost method (tcm), hedonic pricing method, contingent valuation method, and choice modelling approach among others (matthew et al., 2013). 2.2 travel cost method tcm is an indirect method used for estimating user benefits from visits to recreational sites. the expenditure incurred in getting to the site would be considered as a “price” paid by the visitor for usage of the site and underlying assumption of the tcm is the costs incurred visiting a site in some way reflect the recreational value of that site (perman et al., 2003). these variables allow for the estimation of a demand function and the estimation of consumer surplus of recreation sites (freeman, 2003). despite various practical and theoretical problems in this method, it remains a popular technique for estimating the benefits from a particular outdoor recreational site (iamtrakul et al., 2005). tcm is relatively uncontroversial, because it is based on standard economic techniques for measuring value, and it uses information from the visitors to the site. furthermore, tcm is less expensive than the other methods, and the interpretation of results is relatively easier (limaei, et al, 2014; farber et al., 2002). 3. methodology 3.1 theoretical background the itcm proposes the optimisation problem (freeman et al., 2014) described in the equation 1. max u (q, i, z); subject to: tc·q+z = i and t∗=tw+tq where: u represents utility obtained from consuming a quantity of a recreational good q; i is income; z represents the consumption of other goods; and tc are the travel costs. t* is the discretionary time, tw and tq are the time devoted to work and to travel to the recreational site, respectively; and w represents wage. from the first order conditions and assuming rational consumer behavior, the following equation 2 is obtained. q = f (tc, i, z) this denotes the recreational demand function of the site, which is determined by travel cost, consumption of other goods and available income. thus, consumer surplus (cs) per person is given by integration of the demand function. the itcm proposes a function where the frequency of visits approximates the quantity demanded. for a given visitor, the demand of visits to a site follows the equation 3. vi = f (tci, xi)+ei, where: vi represents the number of visits made by the user to a site during a given period of time; tci is the total cost of travel to the site; xi is a vector of additional features including user characteristics such as income, age, or gender, indicators of environmental quality and substitute sites; and ei is an error term (freeman et al., 2014). (1) (2) (3) 54 in the estimation of the previous function, since the number of visits (vi) cannot take continuous values (only integer values), the use of a regression with ordinary least squares can lead to errors. the solution to this is to use a regression model based on a poisson distribution. the poisson distribution assumes that the average number of visits is the same as the variance. however, in practice, this assumption is not met since the data show a greater dispersion. then the most appropriate alternative is the use of negative binomial distributions which allows the variance of the probability function to differ from the mean (haab and mcconell, 2002). there are two other issues associated with the itcm. the first issue is that since the demand for visits is collected through on site surveys and the non-users are not included in the sample, the variable for the annual frequency of visits cannot take zero values. secondly, the probability of being sampled is affected by the number of visits made. thus, a zero-truncated negative binomial regression is used which reduce the potential bias caused by the presence of truncated variables (haab and mcconell, 2002). thus equation 3 can be transformed into the following equation 4. logvi = β0+βtctci+βxxi where: βtc is the coefficient for travel cost and βx represents coefficients for other variables the consumer surplus (for finite travel costs) is given by cs = q/-βtc where: cs is the consumer surplus, q is average of the total annual number of visits 3.2 study site viharamahadevi park is located in colombo 07 (figure 1) with an extent of 18.8 ha (university of moratuwa, 2011). the park is named after queen viharamahadevi, the mother of king gemunu who was an important figurehead of sri lanka‟s history. this park was developed on the land donated by charles henry de zoysa during the british rule of sri lanka and initially named as „victoria park‟ (cmc, 2020). in 2013, with the commencement of the 23 rd commonwealth heads of government meeting in colombo, the government implemented a complete makeover of the viharamahadevi park as a beatification project. the fences and gates around the park were removed which restricted free access of visitors and paved pathways, palm trees were added under the project (lakpura, 2020). (4) (5) karunarathne and gunawardena/ journal of tropical forestry and environment vol. 10 no. 01 (2020) 51-62 55 3.2 data collection the primary source of data for the study was a survey conducted among the visitors of viharamahadevi urban park. a detailed questionnaire was developed based on a pilot study conducted in the site. respondents were asked to report on their origins of travel, travel distances, travel costs (including information on travel modes and travel time), time spent at the site and size of the party. the frequency of travel in a year and the costs spent at the site was also obtained. preferences for park characteristics were obtained under a likert scale and socio economic parameters such as age, education, employment, household size and income were also collected. face-to-face style interviews were conducted to confirm that all questions were properly understood. the survey resulted in total usable 100 responses. 3.3 estimation of the travel cost function and consumer surplus data were summarised first and then analysed using the stata statistical package. total travel cost of individuals was derived using the travel costs (considering the travel mode) and the opportunity cost of time. the following individual travel cost model (equation 6) was estimated using zero truncated negative binomial regression. log v = f (c, e, a, y, h, n, ed) where: v=number of visits made per year by an individual c=individual's total cost of visiting site e=individual‟s estimate of the proportion of the day's enjoyment contributed by the visit a=age of an individual y=income of individual's household h=size of individual's household n=size of individual's party ed=level of education of individual a suitable model with significant variables was selected to establish the demand curve. 4. results 4.1 sample profile table 1 presents the summary statistics related to the sampled respondents. on average the visitation is dominated by relatively young visitors with a mean income of about 50,000 and with a mean travel cost of 1,300. table 2 presents distribution of gender in the sample, indicating that the visitors are male dominant. table 1: summary statistics of the survey respondents. variable mean std. dev. minimum maximum age 38.5 9.22 17 60 income 53,500 23,170.00 12,500 137,500 number of family members 4.43 1.10 2 8 total travel cost 1,306.3 908.60 69 5,076 day enjoyment 4.08 0.49 3 5 number of people visited 4.86 4.13 1 35 annual visits per year 6.68 8.82 1 51 (6) figure 1. location of viharamahadevi park. 56 education 4.24 1.26 2 9 table 2. gender distribution of the sample. category frequency percent (%) male 75 75.0 female 25 25.0 total 100 100.0 source: survey data, 2016 table 3 summarises education level of the survey respondents. within the sample, advanced level qualifications represent the highest percentage (70%) followed by ordinary level qualifications and then by graduates indicating that the park is frequented by educated groups. table 3: education levels of the respondents. education category frequency percent (%) up to grade 5 2 2.0 passed o/l 28 28.0 passed a/l 42 42.0 diploma 5 5.0 graduate 20 20.0 postgraduate 2 2.0 professional courses 1 1.0 table 4: household income distribution. household income per month frequency percent (%) <25,000 1 1.0 25,001-50,000 57 57.0 50,001-750,00 24 24.0 75,001-100,000 15 15.0 100,001-125,000 1 1.0 125,001-150,000 2 2.0 total 100 100.0 household income distribution (table 4) indicates that majority of the sample is in the category of rs. 25,001-50,000. in addition, 81% of the sample is having household income per month in the range of rs. 25,000 to 75,000. according to table 05, majority of sample were employed while self-employed and unemployed categories are next in the list. table 5: employment status of the respondents. job status frequency percent (%) student 7 7.0 employed 52 52.0 self-employed 20 20.0 unemployed 17 17.0 karunarathne and gunawardena/ journal of tropical forestry and environment vol. 10 no. 01 (2020) 51-62 57 pensioner 4 4.0 table 6: travel modes to arrive at the park. travel mode frequency percent (%) bus 31 31.0 own vehicle 43 43.0 on foot 1 1.0 bike 9 9.0 taxi 1 1.0 trishaw 13 13.0 other 2 2.0 table 6 shows that highest percentage of visitors have used their own vehicles. the next highest mode is buses and trishaws and bikes have been used sparingly. table 7: satisfaction about the park. the view the services provided park is clean park facilities easy accessibility relaxing environment enjoyed being in park mean 4.78 3.28 4.77 3.47 3.51 4.55 4.52 median 5.00 3.00 5.00 3.00 3.00 5.00 5.00 source: survey data, 2016 according to the table 7, visitors are more satisfied with the view, cleanliness, relaxing environment, and enjoyment, respectively where mean values are higher than 4.5 as per the likert scale. in addition, it is evident that people expect more improvement in the context of services, facilities and accessibility. 4.2 estimation of the demand function a zero truncated negative binomial regression (ztnbr) was run using stata statistical software. several combinations of variables were tested to select the best model. table 8 gives parameter estimates and full model is given in table 9. table 8: parameter estimates of ztnbr. parameter value number of observations 100 truncation point 0 lr chi2 (4) 18.22 dispersion mean prob> chi2 0.0011 log likelihood -269.80998 pseudo r2 0.0327 table 9: results of the zero-truncated negative binomial regression. variable coefficient std. err. z p>|z| income 0.0000164 5.52e-06 2.97 0.003 total cost| -0.0002009 0.0001442 -1.39 0.164 day enjoyment 0.6700661 0.2432458 -2.29 0.006 number of people visited -0.0761482 0.0332672 -1.95 0.022 constant -1.434487 1.084693 -1.32 0.186 58 lnalpha 0.21889 0.3207997 alpha 1.244694 0.3992976 lr test of alpha=0: chibar2 (01)=338.71prob>=chibar2=0.000 zero-truncated negative binomial regression is used to model count data for which the value zero cannot occur and when there is evidence of over dispersion. the model, as a whole, is statistically significant. the value of the coefficient for income suggests that the log count of visits to the park increases by 0.0000164 for each unit increase in income. this coefficient is statistically significant. this finding is in line with the theoretical expectations. the log count of the visits to the park increases by 0.6701 for each unit increase in day enjoyment. this coefficient is statistically significant indicating that people‟s expectations of the park. it is evident that the log count of visits to the park decreases by 0.0761 for each unit increase in number of people in a group. this coefficient is statistically significant. the total visit cost variable has a negative (-) value which shows that there is an opposite relation between the visit costs and the annual number of visits. in other words, as the visit costs increase, the number of annual visits decreases. thus, this negative relationship is responsible for the negative slope of the demand curve. these findings are consistent with kaliampakos and damigos (1999) and navrud and mungatana (1994). the estimate for alpha is 1.244694. for comparison, a model with an alpha of zero is equivalent to a zero-truncated poisson model. the likelihood-ratio chi-square test that alpha equals zero is 338.71 with one degree of freedom. this is significant result indicates that the negative binomial model is a better choice than a poisson model. further, the variable of the size of the individual household and size of the individual party, age, and level of education have negative (-) values, which means that increase the size of family, the size of the individual party, age and level of education affect the number of the annual visits negatively. other variables of household income and day enjoyment had a positive relationship with the number of annual visits. 4.3 estimation of consumer surplus next, consumer surplus is calculated to derive the recreational value based on the equation 5 indicated under methodology. cs=q/-β cs=6.68/-(-0.0002009) cs=6.68/0.0002009 cs=33,250.37 as per the above calculation, individual‟s annual consumer surplus of the viharamahadevi park is lkr 33,250.37. then social welfare or the aggregated consumer surplus for the site is calculated by multiplying the individual consumer surplus with the number of individuals visiting the site annually (das, 2013). according to the data of colombo municipal council (2016), on average 5,000 individuals visit the park per day. accordingly, total consumer surplus of the viharamahadevi park range from lkr 60,681,925,250 (lkr 60.68 billion) assuming all 365 days with 5000 visitors to lkr 50,706,814,250 assuming 305 days with 5000 visitors (considering 2 months of heavy rainy period). average cs or the annual social welfare is therefore lkr 55,694,369,750 (55.7 billion). this value can be compared with the average land value of the park which is lkr 52,640,000,000 (52.6 billion) assuming an average per perch value of 17.5 million (in 2020 prices). a simple calculation will show that the social welfare can be maximised with the current use of the land. if karunarathne and gunawardena/ journal of tropical forestry and environment vol. 10 no. 01 (2020) 51-62 59 the land were to be sold at its current land value and the money to be invested under the current rates (10%), this would yield annual financial benefit of lkr 5,264,000,000 (5.2 billion). this value has to be adjusted with the environmental damages done to the site with the development activities associated with such an undertaking. in comparison, current land use which is the park will yield annual welfare of lkr 55.7 billion to the users. in addition, the park provides a greenery for the passersby and the rest of the country including its symbolic value and nonuse values, values which are yet to be realised. the estimated individual annual consumer surplus (lkr 33,250.37) is comparable with a value of diyawanna oya wetlands individual cs value of lkr 36,022.35 and the annual consumer surplus of lkr 3,890 million (marawila and thibbotuwawa, 2010). similar studies related to other urban recreational sites indicate much lower values compared to the present study. for example, weras ganga recreational park has a value of lkr 138 million (weerasekara, 2015) and value of nawala park of lkr has been estimated as 130 million (disanayaka, 2015). compared to above two parks viharamahadevi park is located in very significant land lot in the heart of colombo, and it covers 18.8 ha of land. further, recent infrastructure development and park beautifications added immense value to the viharamahadevi park. 5. discussion identification of value of the recreational use of parks is crucial for the sound management and to create the awareness of the services of green spaces for the society in general. the absence of recognising the value of the recreational use of parks may result in degrading and unsound management of these urban parks, making people denied the full use of the services of these green spaces. further, economically efficient resource management requires knowledge of the flow of park benefits and costs, and in that context, valuation can be used to measure the benefits derived from the park. accordingly, this study used itcm which is based on the assumption that travel costs represent the price of access to a recreational site, and peoples‟ willingness to pay for visiting a site is thus estimated depending on the number of trips that they make at different travel costs. accordingly, itcm measures only the 'use value' of recreation sites, and itcm is not capable of producing any total economic value. this is because the basis of the technique is the level of use-based costs incurred by visitors in visiting a site. as per the analysis, the social welfare generated from the recreational use value of viharamahadevi park is lkr 55,694,369,750. this value is on par with other estimates from itcm based valuations of urban areas. data for the study was obtained through a survey of visitors at the viharamahadevi park. non visitors were not sampled nor their concerns are included in the final estimations. multiple purpose trips pose complications in the analysis and sometimes the portioning of the cost is not logical. therefore, this study has only considered only single-purpose trips the actual total welfare generated by the park is much higher considering many other ecosystem services generated by the park including air purification, carbon storage in the vegetation and provision of bird resting site in the middle of a busy city. there are benefits to the passer by community: a green scenery and for a rest of the country a place with greenery and a land mark in the city of colombo. the park can sometimes be congested during school vacations and weekends which may affect the enjoyment obtained by the people. further research (for example, rathnayake and gunawardena, 2013) can be recommended to investigate the effects of such crowding for the benefits obtained by the people. economic values should not be the only concern in justifying environmental policy decisions 60 (gunawardena, 2012). however, estimates that are inclusive of environmental values (pearce et al, 1989) are one of the second best choices available at present. 6. conclusions and policy implications economic values of outdoor recreation could lead to establish better environmental policy decisions. tcm has been mostly used to support such decisions, including investments in recreational infrastructure and recreational management decisions. the estimated annual social welfare value of lkr 55.7 billion for the park implies that the current land use is the best among its many alternative uses. in addition, the park provides a greenery for the passersby and rest of the country derives benefits including its symbolic value and nonuse values, values which are yet to be realised. the unestimated other ecosystem service benefits of the park also provides further economic justification for the park. additional value enhancements of the park while keeping the nature intact and keeping the visitor crowding effects will increase the benefits obtained by the society. creating similar parks at least around the boundary of the city will generate immense welfare to the congested city dwellers. the results of this study will provide justifications for such undertakings in many urban city centers in the country. references ahem, j., 2007. green infrastructure for cities: the spatial dimension, in novotny v. and brown, p. (eds), cities of the future: towards integrated sustainable water and landscape (pp. 267-283), iwa publishing, london. alvarez, s. and larkin, s.l., 2008. valuing recreational benefits of a national park in andean columbia, selected paper prepared for presentation at the southern agricultural economics association annual meetings dallas. barbosa, o., tratalos, j.a., armsworth, p.r., davies, r.g., fuller, r.a., johnson, p. and kevin j.g., 2007. who benefits from access to green space? a case study from sheffield, uk, landscape and urban planning, 83:187-195. chen, w.y. and jim, c.y., 2008. assess and valuation of the ecosystem services provided by urban forests, in carreiro, m.m., song, y.c. and wu, j. (eds), ecology, planning, and management of urban forests: international perspectives(pp. 53-83), springer, new york. cmc, 2020. retrieved june, 15 from https://www.colombo.mc.gov.lk/parks.php. das, s., 2013. travel cost method for environmental valuation, centre of excellence in environmental economics, madras school of economics. davies, r.g., barbosa, o., fuller, r.a., tratalos, j., burke, n., lewis, d., warren, p.h. and gaston, k.j., 2008. city-wide relationships between green spaces, urban land use and topography, urban ecosystem, 11:269-87. disanayaka, d.m.r., 2015. asses the social value of the nawala recreational park-a contingent valuation method, research report of department of estate management and valuation, university of sri jayewardenepura. farber, s.c., costanza, r., and wilson, m.a., 2002. economic and ecological concepts for valuing ecosystem services. ecological economics, 41:375-392. http://doi.org/10.1016/s09218009(02)00088-5. freeman, m., 2003. the measurement of environmental and resource values: theory and methods; resources for the future: washington, dc, usa. freeman iii, a.m., herriges, j.a. and kling, c.l., 2014. the measurement of environmental and resource values: theory and methods. routledge. givoni, b., 1991. impact of planted areas on urban environmental quality: a review, atmospheric environment, 25:289-99. karunarathne and gunawardena/ journal of tropical forestry and environment vol. 10 no. 01 (2020) 51-62 61 gunawardena, u.a.d.p., 2012. an inquiry into ethical foundations of cost benefit analysis. journal of environmental professionals sri lanka, vol. 1 no. 2 haab, t., mcconell, k., 2002. valuing environmental and natural resources: the econometrics of non-market valuation; edward elgar: northampton, uk. heidt, v. and neef, m., 2008. benefits of urban green space for improving urban climate, in carreiro, in m.m., song, y.c. andwu, j. (eds), ecology, planning, and management of urban forests: international perspectives (pp. 84-96), springer, new york. iamtrakul, p., teknomo, k., and hokao, k., 2005. public park valuation using travel cost method, proceedings of the eastern asia society for transportation studies, 5:1249-1264. jackson, l.e., 2003. the relationship of urban design to human health and condition. landscape urban planning, 64:191-200. jayaratne, c.t. and gunawardena, u.a.d.p., 2004. estimation of local recreational value of hakgala botanical garden. proceedings of ninth international forestry and environment symposium of the department of forestry and environmental science, university of sri jayewardenepura, sri lanka, 27-28 february. jorgensen, a., hitchmough, j., and calvert, t., 2002. woodland spaces and edges: their impact on perception of safety and preference. landscape urban planning, 60:135-150. jim, c.y. and chen, w. y., 2006. recreation-amenity use and contingent valuation of urban green spaces in guangzhou, china. landscape and urban planning, 75:81-96. kaliampakos, d., anddamigos, d., 1999. using environmental economics to evaluate quarry rehabilitation alternatives. 60 conference of environmental science and technology. samos. lakpura, 2020. retrieved 15, june from https://lakpura.com/viharamahadevi-park. limaei, s. m., ghesmati, h., rashidi, r. and yamini, n., 2014. economic evaluation of natural forest park using the travel cost method (case study; masouleh forest park, north of iran), journal of forest science, 60:254-261. luttik j., 2000. the value of trees, water and open space as reflected by house prices in the netherlands, landscape and urban planning, 48:161-167. maduwanthika m.c.a. and gunawardena u.a.d.p., 2017. estimation of local recreational value of seethawaka wet zone botanical garden, 22 nd international forestry and environment symposium, organized by: deptment of forestry and environmental science, university of sri jayewardenepura, tangerine beach hotel, kalutara, 10-11 november. marawila t.d. and m. thibbotuwawa, 2010. to develop or to conserve? the case of the diyawanna oya wetlands in sri lanka, (sandee working paper no. 52-10, kathmandu nepal. mathieu, l.f., langford,i.h. and kenyon, w., 2003. valuing marine parks in a developing country: a case study of the seychelles, environment and development economics, 8:373-390. matthew, n.k, shuib, a., ramachandran, s. and herman, s., 2013. demand model of international visitors to the kilim karst geoforest park, langkawi: application of item model, journal of applied economics and business, 1:51-66. navrud, s., and mungatana, e.d., 1994. environmental valuation in developing countries: the recreational value of wildlife viewing, ecological economics, 135-151. pearce, d., markandya, a., barbier, e.b., 1989. blueprint for a green economy. earthscan publications limited, london. perman, r., ma, y., mcgilvray, j. and common, m., 2003. natural resource and environmental economics. pearson education. rakhshandehroo, m., yusof, m.j., m., arabi, r., parva, m., and nochian, a., 2017. the environmental benefits of urban open green spaces. alam cipta, 10:10-15. 62 rathnayake, r.m.w. and gunawardena, u.a.d.p., 2002. estimation of recreational value of the wasgamuwa national park. paper presented at the international conference on relating the environment to regional development organised by usj/ sida/ sarec research co-operation project and ministry of environment and natural resources, colombo, sri lanka, 16-18 september. rathnayake, r.m.w. and gunawardena, u.a.d.p., 2013. social carrying capacity of horton plains national park, sri lanka. sri lanka journal of social sciences, vol 35. rathnayake, r.m.w. and gunawardena, u.a.d.p., 2011. estimation of recreational value of horton plains national park in sri lanka: a decision making strategy for natural resource management. journal of tropical forestry and environment, 1:71-86. smith, r.m., gaston, k.j., warren, p.h., and thompson, k., 2005. urban domestic gardens (v): relationships between land cover composition, housing and landscape. landscape ecology, 20:235-253. takano, t., nakamura, k. and watanabe, m., 2002. urban residential environments and senior citizens longevity in megacity area: the importance of walkable green spaces, journal epidemiol community health, 56:913-18. twerefou, d.k., and ababio, d.k.a., 2012. an economic valuation of the kakum national park: an individual travel cost approach, african journal of environmental science and technology, 6:199-207. tzoulas, k., korpela, k., venn, s., yli-pelkonen, v., kaz ´mierczak, a., niemela, j. and james, p., 2007. promoting ecosystem and human health in urban areas using green infrastructure: a literature review, landscape and urban planning, 81:167-78. ulrich, r.s., simons, r.f., losito, b.d., fiorito, e., miles, m.a. and zelson, m., 1991. stress recovery during exposure to natural and urban environments, journal of environmental psychology, 11:201-230. university of moratuwa, 2011. environmental screening report for model zone development of town hall square, uni consultancy service, university of moratuwa. weerasekara, l.h.p., 2015. an approach of contingent valuation method of weras ganga recreational park, research report of department of estate management and valuation, university of sri jayewardenepura. wickramarachchi, a.h. and gunawardena, u.a.d.p., 2012. estimation of recreational value of leopards at yala national park sri lanka. proceedings of the seventeenth international forestry and environment symposium organised by the department of forestry and environmental science, university of sri jayewardenepura. wu, j., 2008. toward a landscape ecology of cities: beyond buildings, trees, and urban forests, in: carreiro, m.m., song, y.c. and wu, j. (eds), ecology, planning, and management of urban forests: international perspectives (pp. 10-28), springer, new york. zhou, x., and rana, m.m.p., 2012. social benefits of urban green space: a conceptual framework of valuation and accessibility measurements, management of environmental quality: an international journal, 23:173-189. 404 not found wijesingha et al. /journal of tropical forestry and environment vol. 7, no. 02 (2017) 97-107 97 pathological characterization of corynesporacassiicolaisolates from traditional and non-traditional rubber growing areas y.l. wijesingha1*, t.h.p.s. fernando2andk.m.e.p. fernando1 1department of botany,faculty of applied sciences, university of sri jayewardenepura 2department of plant pathology and microbiology, rubber research institute, agalawatta date received:25-10-2017 date accepted: 18-12-2017 abstract rubber (heveabrasiliensis) is one of the major economically important estate crops andgeneratesthe third largest export income of sri lanka. rubber plantations established mostly in wet zone and certain regions in intermediate zone and the cultivated areas are known as traditional areas.however, presently rubber cultivation has been expanded to the dry zone of country and the cultivated areas are known as non-traditional areas. corynesporacassiicola is the most destructive foliar pathogen of the rubber plantcausing corynesporaleaf fall disease (clfd) and the disease has caused a major devastation in rubber industry resultingin a remarkable economic loss. this study aimedto determine the variability ofc. cassiicola isolates from traditional and non-traditional rubber growing areas using pathological factors. ten isolates of c. cassiicolawhich had been isolated from diseased leaves of different clones grown in traditional (five isolates) and non-traditional (five isolates) areas were used for characterization.variability inpathogenicity, temperature sensitivity,growth rate,conidia production,fungicide sensitivity to two fungicides; mancozeb and carbendazim and toxin production were examined. data were statisticallyanalyzedand the final analytical output revealed a statistically significant difference (p <0.05) between the isolates, but not between two geographical regions for all parameterstested except for toxin production and sensitivity to carbendazim. though isolates of c.cassiicolashowsignificant difference in pathological factors among isolates irrespective of geographical location, they do not behave differently in different climatic regions. keywords: corynesporacassiicola, clfd, toxins, traditional and non-traditional areas 1. introduction rubber (heveabrasiliensis) is the major source of natural rubber and cultivated commercially as a plantation crop. rubber has a high demand in local and export market as sheet rubber, crepe rubber and rubber wood which make rubber as income generatingplantation crop in sri lanka. rubber industry is the third largest export income of the country (edb blog, 2015). earlier rubber plantations were mainly confined to the wet zone of the country; kaluthara, kegalla, gampaha, rathnapura, colombo, mathara and galle, and intermediate zone; kurunegala,matale and moneragala administrative districts and rubber growing areas are called as traditional areas. expansion of rubber cultivation to the dry zone; monaragala, vauniya, hambanthotaand ampara administrative district was commenced in 2003(iqbalet. al, 2010) andthese areas under rubber plantations are calledas non-traditional areas (rodrigo, 2007). continuous planting resulting in physicaland chemical property exhaustion of soil,change in land use pattern, urbanization and industrializationand high annual *correspondence: yashodawijesingha92@gmail.com tel: +94713047008 issn 2235-9370 print / issn 2235-9362 online ©university of sri jayewardenepura 98 rainfall being a constraint for latex harvesting have led the expansion of rubber cultivation to new potential sites in non-traditional areas (nugawela, 2002). both traditional and non-traditional rubber cultivations are affected by many biotic and abiotic factors. corynesporacassiicola, a biotic factor causes delay in growth and maturity in immature trees and marked reduction in latex yield of mature trees (jingiet al., 2007).corynesporaleaf fall disease (clfd) causes a significant impact on rubber cultivations in asian and african region(jayasinghe, 2000) and the first clfdepidemic in sri lanka was reported in late 1980’s. the characteristic symptom of the fungus on rubber leaves is known as “railway track-like lesions”. c.cassiicolaisolates show different characteristics in morphology, pathogenicity, toxin production and spore production even though isolates are obtained from the similar agro climatic zone (jayasinghe, 1999;fernando etal., 2012).the diversity and variability of c.cassiicolaare prime important factors to be considered in the development of resistant clone (fernnadoet al., 2009).occurrence of clfd is reported in rubber plantations in non-traditional areas (unpublished data).possibility of emerging different physiological races ofc.cassiicolain different climatic zoneshas not been explored in sri lanka. this study aimed to determine the variability and pathological factors of corynesporacassiicola isolates from traditional and non-traditional rubber growing areas. 2. methodology 2.1collection of isolates ten isolates ofc.cassiicola which had been isolated from symptomatic leaves of different clones grown in traditional and non-traditional areas were obtained from rubber research institute of sri lanka. ten isolates comprisedfive from traditional areas and five from non-traditional areas (table 1). table 1: rubber clones, location and geographical regions of corynesporacassiicola isolates. isolate no. rubber clone location geographical region ta1 rrisl 110 galewaththa traditional tb2 rrisl 200 batuwita traditional tc3 rrisl 202 kuruwita traditional td4 rrisl 217 neboda traditional te5 rric 222 batuwita traditional ntf6 rric 121 thelulla non – traditional ntg7 rric 121 padiyathalawa non – traditional nth8 rric 121 padiyathalawa non – traditional nti9 seedlings monaragala non – traditional ntj10 seedlings monaragala non – traditional wijesingha et al. /journal of tropical forestry and environment vol. 7, no. 02 (2017) 97-107 99 2.2 pathogenicity pathogenicity of the 10 isolates was tested using the detached leaf method (brown and soepena, 1994). aqueous spore suspensions were prepared using tenday old cultures of the isolates grown on pda. conidial density was enumerated using a haemocytometer and inoculum size was adjusted to 1.0×104spores/ml.copper brown leaves of a resistant clone (rrisl 121) and a susceptible clone (rrisl 201) were inoculated with respective spore suspensions. six leaves (replicates) were usedfor each isolate. each leaf was inoculated by placing six drops of spore suspension (10 µl)on both sidesof the mid rib of the upper surface of the leaves. sterile distilled water (sdw) was used as the control. after inoculation, leaves were kept in a humid chamber under approximately 100% rh for 72 h.lesion sizes were measured along the two diameters. 2.3 temperature sensitivity to determine the effect of temperature on growth of each isolate, 5.0 mm mycelial plugs wereplaced centrally on pda medium in 9.0 cm petri dishand incubated at 5, 10, 15, 20, 25, 30, 35 and 40oc for 10 days, and the colony diameter of each isolate was measured along two lines perpendicular to each other throughout the incubation period. five replicates were used for each isolate. 2.4colony growth rate on pda mycelial plugs (5mm diameter) were placed centrally on pda medium in 9.0 cm petri dish. five replicates were used for each isolate. cultures were incubated at room temperature (28±oc)for 10 days. the colony diameter of each isolate was measured along two lines perpendicular to each other throughout the incubation period. 2.5conidia production mycelial plugs (5mm diameter) were placed on pda medium and cultures were incubated at room temperature for 10 days and conidia production (no. of conidia/cm2) was enumerated for each isolate. 2.6 fungicide sensitivity poison food technique was performed. eight-day old mycelial plugs (5mm diameter)were placed on pda medium containing different fungicide concentrations. carbendazim, 2, 3 and 4 ppm andmancozeb, 50, 100, 200, 400, 800, 1000 and 1600 ppm concentrations were in the test medium. three replicates were used for each concentration. plates were incubated at room temperature for 10 days. the colony diameter of each isolate was measured along two lines perpendicular to each other throughout the incubation period. following formula was used calculate percentage of the inhibition. 𝐼 = 100 (𝐶 – 𝑇) / 𝐶 (1) where: i = percentage of the inhibition c = growth in the control without fungicide t = growth in the treatment 2.7toxin production 100 toxic metabolite was extracted using cazpek’sdox broth (cdb). two of the most spore producing isolates from each group (traditional and non-traditional) were selected for the toxin assay. leaf wilt bioassay apple green leaves from the susceptible (rrisl 201) and resistant (rrisl 121) clones were used to detect the toxin activity. broth cultures were prepared using cdb (100 ml)inoculated with 10 day old three mycelial plugs (5 mm) and incubating for different time intervals. after the particular incubation period, crude toxin was filtered through sterile whatman no.1 filter papers. fresh leaves were excised under water and immediately dipped in 5 ml of crude toxin filtrate and leftfor 24 h at room temperature. three replicates were used for each isolate. the control leaves were dipped in 5 ml of sterile cdb. after 24 hours of incubation, leaves were examined for theintensity of wilting and categorized on a visual basis; group i=no reaction, group ii=mild wilting, group iii= moderate wilting, group iv=severe wilting. leaf-wilt bioassay was used to determine the optimum incubation period for toxin extraction where severe wilting is resulted. leaf puncture bioassay toxinswere extracted as described in above and incubated at room temperature for 12 days. after the incubation period, the toxin was extracted filtering through sterile whatman no.1 filter papers and then using milipore membranes. apple green leaves fromclones rrisl 201(susceptible) and rrisl 121(resistant) were collected for leaf puncture bioassay. six leaves (replicates) were used foreach isolate. each leaf was inoculated by placing six drops of the filtered toxic metabolite (20 μl) on both sides of the mid rib of the upper surface of the leaf. sterile cdb was used as the control. after inoculation leaves were kept in a humid chamber under approximately 100% rh for 72 h. the lesion size was measured along two diameters. 2.8statistical analysis data for pathogenicity, temperature sensitivity, growth rate, conidia production, fungicide sensitivity and toxin production were obtained using crd (complete randomized design). data were analyzed using pc sas proc glm version 9.1 (sas institute, cary, north carolina) and the mean separation was done by dmrt (duncan’s multiple range test) at p<0.05 level. 3. results 3.1. pathogenicity disease severity was higher in rrisl 201 infected by ta1 compared to other isolates irrespective of growing region exhibiting highest pathogenicity in the susceptible clone (figure 1). in the susceptible clone, rrisl 201,richmycelial masses were developed from the selected isolatesafter 72 h of incubation. isolate nti9 showed lowest pathogenicity in the resistant clone rrisl 121 while a remarkably higher pathogenicity was observed in clone rrisl 201.different fungal isolates showed a significant variation (p<0.05) on pathogenicity. however, based on duncan’s multiple grouping analysis, pathogenicity of traditional isolates and non-traditional isolates was not significantly different. wijesingha et al. /journal of tropical forestry and environment vol. 7, no. 02 (2017) 97-107 101 figure 1: mean lesion size vs. c. cassiicola isolates for pathogenicity. values are means of six replicates. error bars represent standard error of means.ta1 – te5: isolates from traditional rubber growing areas. ntf6 – ntj10: isolates from non-traditional rubber growing areas. 3.2temperature sensitivity growth of all the isolates was inhibited at 5oc and 40oc (figure 2: a and b). figure 2: growth rate of traditional and nontraditional isolates c. cassiicola in different temperatures. values are means of three replicates. error bars represent standard error of means. ta1 – te5: isolates from traditional rubber growing areas. ntf6 – ntj10: isolates from non – traditional rubber growing areas. 102 the optimum temperature for the growth of isolates ta1 and td4 was 30oc. and for every other isolate, the optimum temperature was recorded as 25oc.different fungal isolates showed a significant variation (p<0.05) on temperature sensitivity.however, based on duncan’s multiple grouping analysis, temperature sensitivity of isolates from traditional isolates and non-traditional isolates was not significantly different. 3.3growth rate isolate ta1 showed the maximum growth rate while te5 showed the minimum growth rate (figure 3). isolates from non-traditional areas showed more or less uniform growth and the growth rates are non – significant. different fungal isolates showed a significant variation (p<0.05) on the growth rate.however, based on duncan’s multiple grouping analysis, the growth rate of different isolates from traditional areas and nontraditional areas was not significantly different. 3.4 conidia production isolates ntf6 and nth8 showed the highest conidia production while isolate td4 showed the lowest conidia production (figure 4). figure 3: growth rate of c. cassiicola isolates from traditional and nontraditional areas. values are means of five replicates. error bars represent standard error of means. ta1 – te5: isolates from traditional rubber growing areas. ntf6 – ntj10: isolates from non-traditional rubber growing areas. figure 4: conidia production per area of traditional and nontraditional c. cassiicola isolates. values are means of three replicates. error bars represent standard error of means. ta1 – te5:isolates from traditional rubber growing areas. ntf6 – ntj10: isolates from non-traditional rubber growing areas wijesingha et al. /journal of tropical forestry and environment vol. 7, no. 02 (2017) 97-107 103 rest of isolates produced more or less same amount of conidia. different fungal isolates showed a significant variation (p<0.05) on conidia production. however, based on duncan’s multiple grouping analysis, conidia production in traditional isolates and non-traditional isolates was not significantly different. 3.5 fungicide sensitivity variability in the sensitivity to the fungicide, mancozeb isolate nti9 exhibited the minimum percentage inhibition for all concentrations. the isolates; ta1, td4 and ntf6 expressed the highest percentage inhibition for 50ppm, 100–800ppm and 1000– 1600ppm respectively (figure 5).different fungal isolates showed a significant variation (p<0.05) on sensitivity to the fungicide, mancozeb. however, based on duncan’s multiple grouping analysis, sensitivity of isolates to mancozeb from traditional isolates and non – traditional was not significantly different. figure 5: percentage inhibition of traditional and nontraditional c. cassiicola isolates in different concentrations of mancozeb. values are means of three replicates. error bars represent standard error of means. ta1 – te5: isolates from traditional rubber growing areas. ntf6 – ntj10: isolates from non-traditional rubber growing areas 104 variability in the sensitivity to the fungicide, carbendazim growth of ten isolates wastotally inhibited at 4 ppm carbendazim concentration while 95% of growth inhibition observed in tc3 (figure 6).different fungal isolates didnot show a significant variation (p<0.05) on sensitivity to the fungicide,carbendazim. 3.6. toxin production results of the leaf wilt bioassay showed sufficient toxin production in cdb broth inoculated with mycelial plugs after 12 days of inoculation. therefore, leaf puncture bioassay was done using 12 day old broth culture. toxin activity indices in the susceptible clone were higher compared to the resistant clone (figure 7). different fungal isolates showed a significant variation (p<0.05) on toxin activity. the toxin activity of the selected isolates demonstrated two different statistics. in the resistant clone (rrisl 121) toxin activity of isolate ta1 and isolate ntf6 expressed a statistically significant difference. duncan grouping confirmed this difference. isolate ntf6 expressed more toxin activity than the isolateta1. figure 6: percentage inhibition of traditional and non-traditional c. cassiicola isolates in different concentrations of carbendazim. values are means of three replicates. error bars represent standard error of means. ta1 – te5: isolates from traditional rubber growing areas. ntf6 – ntj10: isolates from non-traditional rubber growing. ( b) wijesingha et al. /journal of tropical forestry and environment vol. 7, no. 02 (2017) 97-107 105 however, in the susceptible clone (rrisl 201), such significant difference could not be observed in the toxin activity by the two isolates. duncan grouping confirmed the absence of difference. however, according to duncan grouping, the toxin activity of the isolate ta1 in rrisl 201was slightly higher than isolate ntf6. 4. discussion presently, rubber is grown as plantation crop in traditional and non-traditional areas of the country. destructive foliar disease corynespora leaf fall occurs in non-traditional areas too. however, characterization of c. cassiicola isolates from new locations in the dry zone has not been done which is important in designing management strategies. present study focused on investigating variability of c.cassicola isolates from two different geographical regions. results reveal that the pathogenicity of c.cassicola isolates varies between susceptible and resistant clones. the same results were found in a previous study which reports variability of pathogenicity among isolates of c.cassicola (cheeet al., 1987). pathogenic effect was higher in all isolates in the disease susceptible clone rrisl 201 compared to resistant clone rrisl 121. although there is a significant difference between the isolates, difference in pathogenicity between the two geographical regions is non-significant.it is evident that a significant variation in the growth pattern of the selected isolates of c.cassiicola and the findings agree with the observations of fernando et.al (2009) where all c.cassiicolaisolates examined, had shown similar growth patterns on pda witha significant variation in the growth rates.present study based on two different climatic zones reveals that there is no significant difference in growth rate between the two geographical regions.results revealed that the optimum temperature for the growth of c.cassiicolaisolateslie in the range of 25 -30oc. previous studies also reported the optimum temperature is between 25-30oc for c. cassiicolamycelial growth, and 30oc is the most favorable temperature (chunxiaet al., 2010). however, isolates didnot express a significant difference in the temperature sensitivity between the two geographical regions where temperature difference exists over the year with different monsoons. variation in conidia production under controlled environmental conditions was observed in test isolates irrespective of origin of isolates. similar finding is reported; typical slender, needle shaped conidia and significant variation in conidia production in different c.cassiicola isolates (schlubet figure 7: mean lesion size vs. c. cassiicola isolates for toxin activity. values are means of three replicates. bars represent standard error of means. ta1 – te5: isolates from traditional rubber growing areas. ntf6 – ntj10: isolates from non – traditional rubber growing areas. 106 al.,2012). results of the present study reveal a slight variation in production in different isolates indicating different climatic conditions do not affect conidia production. hence, present findings provide the information on the similar potential of secondary infection in both geographical regions. mancozebis the mainly used fungicide to control clfd. but due its adverse effects on the environment, rubber research institute is now promoting carbendazim, which has shown low toxicity levels. therefore, both of fungicides were evaluated inthis study. it was found that both mancozeb and carbendazimare effective fungicides against tested isolates from both regions and effective concentrations of different fungicides are totally different. the results of the present study are agreeable with the results of previous study on mancozeb and carbendazimagainst c.cassiicolafrom rubber plants reported by fernando et al., (2010). when comparing both fungicides, carbendazim showed drastically low inhibition concentrations. since inhibitory effect of carbendazim on growth of all tested isolates is higher compared to mancozeb, carbendazim can be recommended as effective fungicide against c. cassiicolaisolates in the country. in the chemical control of corynespora leaf fall disease, carbendazim is a promising chemical agent to achieve successful growth suppression with minute amounts. further, it provides direct economic advantage as an effective product. on the other hand, environment pollution due to excessive amounts of chemicals can be minimized with application of fungicides in reduced amounts. however, it is important to evaluate its possible negative effectsbefore applying it in large scale plantations.susceptibility or resistance of a clone is determined by the ability of a pathogen to establish in that particular clone. in nature, toxic metabolite production is commenced after the establishmentof the pathogen inside the plant tissue. in this study toxins were applied externally for the bioassay, and lesion development was taken as the effect of toxin on pathogenic activity of c.cassiicola on susceptible and resistant clones. when considering the toxin activity between the two geographical regions, a significant difference was observed between the two geographical regionsin both susceptible and resistant clones. in a previous study, it was observed that there is variability in the virulence of different c.cassiicola isolates. this difference was resulted by a gene called cas, which is responsible for the production of the toxin, cassiicolin (reshmaet al., 2016). pathogenicity of c.cassiicola in corynespora leaf fall disease of rubber is related to a host selective toxincassiicolin (breton etal., 2000). it is evident that pathogenicity factor, cassiicolin production rate of individual isolates determines the degree of pathogenicity of individual isolate in different geographic regions. prevailing climatic conditions in non-traditional areas favors considerable amount of toxin production even in resistant clone rrisl 121. when in view of these results, it is apparent that hevea clone might play a role in the different manner in toxin activity of isolates from different geographical regions. present study shows there is no remarkable difference between the isolates from two geographical regions. this may be due to the climatic difference between two regions not being diverse enough for the emergence of new physiological races. moreover, since similar hevea clones are cultivated in both regions probability of developing altered pathogenic factors within a short duration is low. 5. conclusions present study shows there is no remarkable difference between the isolates from two geographical regions. this study reveals that carbendazim is a promising fungicide against corynesporacassiicola isolates found in different regions and the fungicide, carbendazim can be used in clfd management in traditional and non-traditional rubber growing areas of the country. wijesingha et al. /journal of tropical forestry and environment vol. 7, no. 02 (2017) 97-107 107 references brown, a.e. andsoepena, p. 1994. pathogenicity of colletotricumacutatum and c. gloesporiodesonhevea spp. mycological research.98, 264-266. breton, f., sanier, c. and d'auzac, j. 2000.role of cassiicolin, a host-selective toxin, in pathogenicity of corynesporacassiicola, causal agent of a leaf fall disease of hevea. journal of rubber research.3(2),115-128. chee, k. h., 1987. studies on sporulation, pathogenicity and epidemiology of corynesporacassiicola on hevearubber.proceedings of the irrdb symposium. thailand, chiang mai. 6 – 17. chunxia, z., mingxia, h., jiazhi, l., jinqiang, w., guizhi, j. and jianyong, h. 2010. biological characteristics of corynesporacassiicola causing corynespora leaf fall disease. plant protection.2, 25. edb blog. 2015. the natural rubber industry of sri lanka. [online] available at: http://www.srilankabusiness.com/blog/sri-lanka-natural-rubber-industry.html. [accessed: 26 november 2016] fernando, t.h.p.s., jayasinghe, c.k., wijesundera, r.l.c. and siriwardena, d. 2009. variability of hevea isolates of corynesporacassiicolafrom sri lanka. journal of plant diseases and protection. 116 (3), 115 – 117. fernando, t.h.p.s., jayasinghe, c.k., wijesundera, r.l.c. and siriwardena, d. 2010. screening of fungicides against corynespora leaf fall disease of rubber under nursery conditions. journal of plant diseases and protection. 117(3), 117 121. fernando, t. h. p. s., jayasinghe, c. k., wijesundera, r. l. c. and siriwardane, d. 2012. some factors affecting in vitro production, germination and viability of conidia of corynesporacassiicola from heveabrasiliensis. journal of the national science foundation of sri lanka., 40(3), 241–249. iqbal, s.m.m., rodrigo, v.h.l. and karunathilake, p.k.w. 2010.feasibility of rubber (heveabrasiliensismuell. arg.) cultivation in eastern province of sri lanka with the peasant community. journal of the rubber research institute of sri lanka.90, 18-30. jayasinghe, c.k., silva, w. p. k. and wettasinghe, d. s. 1999. syptoms on hevearubber.bulletin of the rubber research institute of sri lanka.39, 1–5. jinji p., zhang x., qi y., xie y., zhang h. and zhang h. 2007.first record of corynespora leaf fall disease of hevea rubber tree in china.australian plant disease notes 2.35 − 36. nugawela, a. 2002. the need to expand cultivation of rubber into alternate areas of the country: a technological perspective. bulletin of the rubber research institute of sri lanka. 44, 69–71. jayasinghe, c. k. 2000. corynesporaleaf fall: the most challenging rubber disease in asian and african continents.bulletin of the rubber research institute of sri lanka. 42, 56–64. reshma, m., philip, s., rose, d., joseph, a., prem, e. and joseph, j.2016. pathogenicity and toxin production of corynesporacassiicola isolates causing corynespora leaf fall disease in heveabrasiliensis. rubber science. 29(3), 277-285. rodrigo, v.h.l., 2007. ecophysiological factors underpining productivity of heveabrasiliensis. journal of plant physiology. 19(4), 245-255. schlub, r.l. and smith, l.j. 2007. diagnostic features of corynesporacassiicola and its associated diseases. npdn national meeting abstract. january, 39. issn 2235-9370 print / issn 2235-9362 online ©2017 university of sri jayewardenepura issn 2235-9370 print / issn 2235-9362 online ©university of sri jayewardenepura issn 2235-9370 print / issn 2235-9362 online ©2017 university of sri jayewardenepura (1) issn 2235-9370 print / issn 2235-9362 online ©2017 university of sri jayewardenepura (2) issn 2235-9370 print / issn 2235-9362 online ©2017 university of sri jayewardenepura (3) issn 2235-9370 print / issn 2235-9362 online ©2017 university of sri jayewardenepura (4) issn 2235-9370 print / issn 2235-9362 online ©2017 university of sri jayewardenepura (5) issn 2235-9370 print / issn 2235-9362 online ©2017 university of sri jayewardenepura (6) issn 2235-9370 print / issn 2235-9362 online ©2017 university of sri jayewardenepura (7) issn 2235-9370 print / issn 2235-9362 online ©2017 university of sri jayewardenepura (8) chapter five: discussion 40 identification and quantification of tree species in open mixed forests using high resolution quickbird satellite imagery s. arockiaraj 1 , a. kumar 2* , n. hoda 3 , a.t. jeyaseelan 4 1 integrated coastal and marine area management project directorate, ministry of earth sciences, chennai, india 2 center for land resource management, central university of jharkhand, ranchi, india 3 jharkhand space applications center, department of information technology and egovernamce, jharkhand, ranchi, india 4 national remote sensing center, department of space, hyderabad, india date received: 25-05-2015 date accepted: 01-08-2015 abstract present study deals with identification and quantification of tree species within an open mixed forest in parts of ranchi district jharkhand, india using high resolution quickbird satellite data using image processing and gis techniques. a high resolution quickbird satellite image was used for shadow enhancement and tree crown area extraction. the first principal component of quickbird satellite images was employed to enhance the shadowed area and subsequently shadow and nonshadow area were classified using isodata. the satellite image was used for crown area extraction with standard deviation of ndvi value and the crowns were classified into five classes using maximum likelihood supervised algorithm. result shows that barring few limitation, the high resolution quickbird image provides rapid and accurate results in terms of identification and quantification of tree species in conjugation with field verification and attained 88% of classification accuracy. it reduces the time required for obtaining inventory data in open mixed forest. results also showed that total 5,522 trees of various species were present in the study area and dominated by shorea robusta (80.48%) followed by ziziphus mauritiana (16.26%), unknown tree (1.81%), ficus religiosa (0.98%) and mangifera indica (0.47%). the demography patterns of the locals mainly tribal (89.9%) exhibited their direct as well as indirect dependency on mixed forests resources for their subsistence and livelihood. the study necessitate towards the effective implication of policies to raise the standard of living of tribal people in the region. keywords: open mixed forest, tree quantification, tribal people, quickbird, remote sensing 1. introduction forests provide invaluable ecological services for the environmental security as well as provide a wide spectrum of livelihoods especially to the rural and marginalised strata of society in the form of direct employment, self-employment and secondary employment. forests are rich sources of timber, firewood, bamboo, fodder and at the same time they provide employment opportunity to a large section * correspondence: amit.iirs@gmail.com tel: +91 8603860814 issn 2235-9370 print/issn 2235-9362 online © university of sri jayewardenepura arockiaraj et al. /journal of tropical forestry and environment vol. 5. no 02 (2015) 40-53 41 of the tribal and other disadvantageous rural communities (fsi, 2011; ajaz-ul-islam, 2013). forest is the second largest landuse in india after agriculture covering 21.05% of the total geographical area of the country. state of forest report (2011) states that jharkhand state has 23,605 km 2 of recorded forest area, which is 3.06% of national coverage and produces 130,000 m 3 yr -1 (i.e., 0.4% of the national estimated production). that report also indicates that 16% of total livestock depends on forests in jharkhand against the national average of 38.49% (fsi, 2011). mixed forests represent significant proportion (30%) of the world’s forest resources. this forest ecosystem is subjected to rapid adverse changes due to natural and anthropogenic influences due to its multifarious advantages. various factors influencing the forest ecosystem and for proper management based on rational exploitation and development of forest resources is on scientific lines. proper and sustainable management of forest resources require spatio-temporal coverage and species-wise vegetation quantification. there are prevalent various conventional methods of ground surveys techniques in order to collect reliable required data. however, field survey is more accurate but time consuming and remote sensing analysis together with field survey is more economical both in terms of time and money provided the precision is satisfactory. the forest cover mapping and species identification through remote sensing technology in conjugation with field inputs is very popular in recent decades using mainly courser to medium resolution satellite data (tm, liss-iii etc.). tree counting outside forest is also in practice employing medium resolution satellite data (seiler and mcbee, 1992; maco and mcpherson, 2002; fsi, 2011), but identification of tree species in open mixed forest employing high resolution satellite (hrs) images remote sensing technology is under research due to spectral mixing of vegetation species and degradation (brandtberg, 1998). launch of a very high spatial resolution satellites (ikonos, quickbird, orbview) in the last decade, as well as development of new classification algorithms have initiated a new era in forest management using remote sensing technology (plantier et al., 2006). very high spatial resolution satellite images such as ikonos and quickbird have the potential to generate regional scale forest analysis through fusion of digital image analysis techniques with ground based forestry (greenberg et al., 2005). moreover quickbird satellite data is being used for bathymetric mapping (lyons et al., 2011), detection of new plastic greenhouses (agüera et al., 2006), generation of digital surface model using stereo pairs (crespi et al., (2007), for mapping impervious surface distribution (lu, 2011), delineation of soil erosion-prone areas (uddin et al., 2014), stem volume estimation by tree crown area (ozdemir, 2008), classifications for mapping and discriminating pyrus bourgaeana trees within a mixed mediterranean forest (arenas-castro et al., 2014). quickbird characteristics provide an opportunity for capturing quantitative parameters of floristic changes across small topographic gradients at a very fine spatial resolution to capture spectra from individual units such as a tree crown (souci, 2008). inventory attributes depend on whether the stand types were predominantly comprised of coniferous, deciduous or mixed wood species (hall and skakun, 2007). tree attributes and spectral response patterns of high resolution quickbird satellite image have shown strong association. band 2 (green) and band 3 (red) in the visible region and band 4 (nir) have revealed significant associations with forest parameters (islam and donoghue, 2004). culvenor et al. (1999) proposed timbrs, a semi-automated algorithm, originally developed for eucalyptus forests. identification and quantification of trees species using high resolution satellite data have some limitations. in case of standing trees in crop field, the pixels of the tree cover mix up with the crops in the field and also in case of leaf fall, the sensor cannot capture the actual status of the tree cover (singh et al., 2005). although remotely sensed imagery provide an accurate total tree count, its 42 accuracy depends upon the image resolution (spatial and spectral) properties adopted against the type of forest and its age class. on the other hand, individual tree sampling could provide an alternative method to plot-based inventory, avoiding per hectare sampling variation across the standing trees (deadman and goulding, 1979; gordon et al., 1995; 2006). mather (2004) emphasised on the multiband visible/ near infrared images of vegetated areas that will exhibit negative correlations between the near infrared and visible red bands. principal component analysis (pca) technique is commonly used on the image to de-correlate it. pca2 is likely to be most suitable for the vegetation features as it emphasises highly on the uncorrelated features of the bands. pca1 contains variability due to overall scene brightness (nag and kudrat, 1998). in the present study, an attempt was made to evaluate the potential of very high resolution quickbird satellite data in identification and quantification of tree species in the open mixed forests, ranchi, jharkhand using shadow enhancement and crown area extraction techniques. later, livelihood contributions of enumerated tree species to the tribal people were evaluated. 2. methodology 2.1 study area this study was conducted in numkum block, the southern region of ranchi district of jharkhand state, india located between 23 o 12ʹ n to 23 o 11ʹ n latitude and 85 o 17ʹ e to 85 o 18ʹ e longitude at an elevation of 510 m above mean sea level (figure 1). it covers total area of ca. 332.77 ha and consists of rural set up with primarily covering kalamati village (khunti district) and small parts of dundu of ranchi district, nehaldih and argoi villages of khunti district. the study area is a complex of plains and hilly region with the undulating landscape. the existing landuse pattern is as natural and open mixed forest, un-irrigated cultivable land, cultivable and uncultivable wasteland. majority of forest area comprises of ziziphus mauritiana, ficus religiosa, shorea robusta, mangifera indica l. figure 1: location and the detailed map of the study area. arockiaraj et al. /journal of tropical forestry and environment vol. 5. no 02 (2015) 40-53 43 the population is 299 persons (145 males and 154 females) in kalamati village, 625 persons (298 males and 327 females) in dundu village, 86 persons (46 males and 40 females) in nehaldih village and 96 persons (52 males and 44 females) in argoi village (census, 2001). the area falls under tropical climate with three distinct and well-marked seasons, summer, monsoon and winter. the average annual normal rainfall is 1,400 mm; the mean minimum temperature is 22° c and the mean maximum temperature is 38° c in the area. the educational, medical, social, economic, irrigation, communication and transportation facilities in these villages are very limited and in poor condition. the livelihood systems in the area are primarily dependent on combinations of forests, labouring and agriculture. the forest resources are the important contributor to the total livelihoods among the tribal communities in the area. the people are relied on diversified pattern of occupations, as no single activity provides sufficient resources to entirely ensure their livelihood (malik et al., 2011, sinha and kumar, 2013). 2.2 methodology in the present study, a quickbird satellite image acquired on 26 th december 2006 was used. quickbird satellite carries a single instrument capable of producing panchromatic images with a spatial resolution of between 0.61 and 0.73 m plus multispectral imagery with a spatial resolution of 2.44 and 2.88 m at nadir and off nadir respectively. the sensor has across track mode and swath of 16.5×16.5 km at nadir. it has 04 multispectral (mss) and 01 panchromatic (pan) bands. the spatial resolution of panchromatic image is 65 cm and multispectral image is 2.62 m. the details of the sensor are provided in table 1. table 1: sensor specification of quickbird satellite. characterisation information launched on 18 october 2001 orbit altitude 450-km orbit inclination 97.2°, sun-synchronous swath 16.5 km x 16.5 km at nadir radiometric resolution 11-bits per pixel revisit time 1 to 3.5 days, depending on latitude (30° off-nadir) spatial resolution sub-meter resolution 65 cm panchromatic at nadir 2.62 m multispectral at nadir spectral resolution 4 multispectral and 1 panchromatic bands wavelength region (µm) 1 0.430-0.545 (blue) 2 0.466-0.620 (green) 3 0.590-0.710 (red) 4 0.715-0.918 (near-ir) pan 0.405-1.053 the fusion of images can enhance the recognition ability of features (wenbo et al., 2008). in the present study, panchromatic and multi spectral images of quickbird satellite were fused using the principal component technique (shamshad et al., 2004). experimental results showed that the results from pan-sharpened images are significantly better than original multispectral images (zhang 2002; 44 wang et al., 2005). the fused image was then geo-rectified using the cartosat-i image acquired on december 2005 (2.5 m spatial resolution) in utm projection system and wgs 84 datum using adequate number of ground control points. the rms error was 0.40 m. all the digital image processing and gis analysis were carried out using erdas imagine 9.2 and arcgis 9.2 respectively. later in the study, pca 1 was performed for the shadow enhancement and the output decorrelated image was then subjected to isodata (iterative self organizing data analysis technique) classification. this technique assigns each candidate pixel to a cluster. the isodata algorithm was repeated by modifying the criteria until the appropriate separation of shadow enhancement was achieved. the maximum iterations were limited to 10 times with only 02 classes for shadowed and non-shadowed area. due to the less spectral variability between the shadowed area and water body, ndvi (normalized difference vegetation index) was performed on multispectral quickbird images to extract water bodies (pixel values ≤ 0). this image was used to mask the water body areas from the classified image (figure 2). figure 2: shadow enhanced area of pan-sharpened quickbird image. in the open mixed forest while captured through the off-nadir angle, there was some overlapped crown area comprising of multiple crowns. these compactly clustered trees pose a difficulty in counting the individual number of trees. therefore, the multispectral quickbird satellite image was arockiaraj et al. /journal of tropical forestry and environment vol. 5. no 02 (2015) 40-53 45 subjected to ndvi (normalised difference vegetation index). ndvi normalises the difference of brightness values from infrared and red for monitoring vegetation (rouse et al., 1993). the standard deviation 1 (σ) of ndvi image (i.e., ndvi threshold >0.028) was used to extract the tree crown area from the quickbird satellite image. the output image has pixel values of mature trees as well as the low laying shrubs. here, it was observed that at many places the low laying shrubs also approximately have the similar ndvi values as compare to the mature trees. therefore, the original pixel values of tree crown cover were extracted using the ndvi threshold value from multispectral quickbird satellite image, and thereafter subjected to supervised classification. crown area was divided into five classes. homogenous tree classes were extracted individually and vectorised (figure 3). tree crown area and enhanced shadowed area were merged. the merged image represents mature individual tree, mature clustered trees as well as crown shadow. trees having shadow represent mature status and were retaken into consideration for the tree quantification and species identification. figure 3: extracted crown area (in vector) overlaid on high resolution quickbird satellite image. supervised classification method was used in this study with the maximum likelihood (ml) classifier. while working through ml algorithm, it is necessary to have well defined training areas and 46 pure signatures to acquire an expected result (jensen, 1996). since quickbird image is of a high resolution data, the signatures sites can clearly be delineated (frick et al., 2005). as maximum number of training sites contribute to the higher classification accuracy, therefore, the types of trees were identified using the supervised classification with fifty numbers of training sites for each class (except m. indica l., which is less than 50 in numbers within the study area). based on the spectral characteristics of species and adopted classification algorithm, the tree cover was regrouped into 10 classes. for accuracy assessment, 100 points were taken for ground verification (conducted on october 2009) with minimum of 15 points against each class. the overall classification accuracy was 88%. the producer accuracy of classes ranges from 60% to 97% and the user accuracy ranges from 66% to 100% with overall kappa statistic of 0.83 (table 2). wrong identification of pixels was corrected using recoding technique and the final classified image was used for tree quantification of particular class. five types of tree species were present viz., z. mauritiana, ficus religiosa, s. robusta, m. indica l. and unknown tree. thereafter, each class was extracted individually and converted into vector format. the vector was then used in quantification of individual trees and trees in each cluster. all the five types of classified tree crowns were extracted separately and then converted to vector for the area based statistics calculation. quantification of trees was based on the sample mean crown area of each type. there were at least 20 sample tree crowns selected for each type and their mean crown value were calculated, which is 48.18 m 2 for z. mauritiana, 207.49 m 2 for f. religiosa, 35.73 m 2 for s. robusta, 214.81 m 2 for m. indica l., 82.33 m 2 for unknown tree (table 3). the mean values (mean crown area) of sampled crown were used for quantification of each homogeneous tree type. the consideration of individual trees was made, where crown area of a particular tree falls within the mean value of that particular tree type. whereas the consideration of tree cluster of a particular tree type were made, where the crown area value is more than the mean crown area. the tree clusters of each type were extracted from the classified image and the number of trees was derived through the following derivation (equation 1). (1) where: n = number of trees b = crown area of the multiple crowns and m = mean value of the sampled crown area table 2: accuracy assessment of classified image. species producers accuracy users accuracy kappa ziziphus mauritiana 97.50% 88.64% 0.81 ficus religiosa 60.00% 100.00% 1.00 unknown tree 73.33% 91.67% 0.90 shorea robusta 93.75% 85.71% 0.79 mangifera indica l. 66.67% 66.67% 0.65 overall classification accuracy = 88.00% overall kappa statistics = 0.83 arockiaraj et al. /journal of tropical forestry and environment vol. 5. no 02 (2015) 40-53 47 308 51 45 236 23 590 3 55 4208 3 0 1000 2000 3000 4000 5000 z. mauritiana f. religiosa unknown tree s. robusta m. indica l. n u m b e r o f tr e e s tree species individual tree species tree species in cluster table 3: crown area estimation and quantification of individual tree species and tree species in cluster. species individual species species in clusters total no. of species % of the total species mean crown area (m 2 ) no. of species no. of species in clusters mean crown area (m 2 ) no. of species z. mauritiana 48.18 308 147 48.18 590 898 16.26 f. religiosa 207.49 51 03 207.49 03 54 0.98 unknown tree 82.33 45 14 82.33 55 100 1.81 s. robusta 35.73 236 527 35.73 4208 4444 80.48 m. indica l. 214.81 23 01 214.81 03 26 0.47 total 393 4859 5522 100.00 3. results and discussion the tree species within an open mixed forest were identified and quantified using very high resolution quickbird satellite data using shadow enhancement and crown area extraction techniques. the open forest comprised of matured trees, tree clusters, bushes, cultivable land and bare soil cover. the improvement in spatial resolution of satellite imageries also implies to make use of other image characteristics viz., shadows (irvin and mckeown, 1989; arévalo et al., 2008). shadow of the mature trees as well as tree clusters is a significant attribute associated with the satellite imagery. therefore, the shadow was used to distinguish the matured trees from low lying vegetation (shrubs). also, the livelihood contributions of enumerated tree species to the tribal people were studied. 3.1 tree species quantification according to this study, total of 5,522 trees were present within the study area during 2006 (table 3, figure 4). figure 4: quantified individual tree species and tree species in cluster as observed through high resolution quickbird satellite data. 48 among individual species within the study area, z. mauritiana was counts the maximum (308) followed by s. robusta (236). f. religiosa was 51. there were 45 unknown species. m. indica l. was the least among the individual tree species. among the species in clusters, s. robusta had the maximum (4,208) followed by z. mauritiana (590) and unknown tree (55). on the contrary, f. religiosa (03) and m. indica l. (03) were the minimum. the total individual species and species in clusters exhibits that the majority of species in the study was s. robusta (80.48%; n=4,444) followed by z. mauritiana (16.26%; n=898), unknown tree (1.81%; n=100), f. religiosa (0.98%; n=54) and m. indica l. (0.47%; n=26). 3.2 demography pattern the population in these villages are very limited (1,106 persons in 2001 and 3,643 persons in 2011), though an increase (229% growth) were observed during 2001-11. village-wise population exhibits that the maximum growth was observed in nehadih village (459) followed by kalamati villages (1,454), argori (430) and dundu (194) (figure 5 (a) and (b)). it also exhibit that the village dundu and kalamati most populated village in the study area. figure 5: human population in villages during (a) 2001 and (b) 2011. (source: census of india, 2001 & 2011). the demographic composition represents that major chunk of population in the study area belong to schedule tribe (st). as mapped during census year, the 89.9% of population was st in 2001 and the percent ratio increased to 90.3% in 2011, whereas the population of schedule caste (sc) was very limited to 0.6% in 2001, which increased to 1.4% in 2011. the village wise distribution exhibit that maximum increase in actual number of persons was in kalamati village followed by dundu village (figure 6 (a)). the per cent increase of total, st and sc population represents maximum increase in kalamati village followed by nihaldih village and argori village (figure 6(b)). the demographic composition with reference to gender in the villages exhibits comparable male female ration as surveyed during census year in 2001 (51.1% female against 48.9% male) and 2011 (50.3% females against 49.7% male). the village-wise male: female ratio represents that the female population is always higher compare to male population in the villages except nehaldih village in 2001 and 2011 and in argori village in 2001 (figure 6 (c)). (a) (b) arockiaraj et al. /journal of tropical forestry and environment vol. 5. no 02 (2015) 40-53 49 figure 6 (a): demographic composition (st/ sc) during 2001-11. figure (b): percent change in total population and demography composition (st/sc) during 2001-11. figure 6(c): demographic composition (male, female) during 2001-11 in the villages of study area. (source: census of india, 2001 & 2011). 3 1 .0 4 8 6 .3 5 3 3 .7 4 4 7 .9 0 4 5 7 .1 0 0 2 8 .4 6 3 4 .3 4 6 9 .8 3 9 1 .1 0.0 200.0 400.0 600.0 800.0 dundu kalamati nehaldih argori % c h a n g e villages total population sc population st population 0 7 0 0 602 216 86 90 23 76 0 6 4 39 8 0 773 1586 490 442 42 128 47 84 0 400 800 1200 1600 2000 dundu kalamati nehaldih argori dundu kalamati nehaldih argori n u m b e r o f p e r so n s villages sc st other sc st other 2001 2011 298 145 46 52 327 154 40 44 393 872 289 256 426 881 256 270 0 400 800 1200 1600 2000 dundu kalamati nehaldih argori dundu kalamati nehaldih argori n u m b e r o f p e r so n s villages male female male female 2001 2011 50 3.3 tree quantification and the local people the demography pattern in the villages exhibits that the major chunk of the population is tribe and relied on these local forest resources for their livelihoods through the sale of fuel wood and fodder, livestock rearing, grazing, forest based handicrafts and cottage industries, leaf plate making, liquor making, rope making and basketry, medicines, collection and marketing of non-timber forest products, bidi making, timber yielding, cultivation of agricultural crops etc. identification of tree species in the forest ensures the reliability of livelihood and income sources for the local people. shorea robusta is the timber yielding tree, whereas mangifera indica and ziziphus mauritiana are basically fruit plant. also ficus religiosa and mangifera indica are religiously important and shorea robusta and the unknown tree are being used as fuel wood by the locals. the name of tree species and their use category are listed in table 4. 4. conclusion the study exhibits the potential of high resolution quickbird satellite data for tree quantification in the open mixed forest area using image processing, gis techniques. the crown area extraction and its relation with shadow area in identifying the mature tree clusters were achieved with 88% of accuracy, when compared with the field information. the high resolution quickbird image provides accurate results in terms of identification and quantification of tree species in conjugation with field verification. the inaccuracy pertaining to the classification may be minimized through incorporating high number of training sites during post field classification process and tanking pure pixels. though, the study represents certain limitation in quantification of species in tree clusters. the major limitation of tree quantification is obstructed in the tree clusters, where the immature trees (of varied ages) within the middle of tree clusters. trees along with the shrubs and bushes may also reduce the accuracies of tree quantification. as the study deals with the tree identification specifically in the open mixed forest, the classification of tree types using the maximum likelihood classifier, if enhanced more than 88%, the crown area will have a more accurate result. also the crown area measurement is sensitive to the choice of season. barring few limitations, the methodology may help in rapid assessment of tree cover spread in open mixed forest and trees outside forest, thus assist in decision making. it also ensures the subsistence and livelihood of the local tribal people. the demography patterns of the locals exhibited their direct as well as indirect dependency on mixed forests. and the different tree species enumerated in the study were being used to fulfill different day today need of the local people. the high resolution remotely sensed images may also necessitate towards the effective implication of various policies to uplift the standard of living of tribal people in the region. table 4: usage of forest species enumerated in the study. species local name as used by the local people ziziphus mauritiana ber fruit ficus religiosa pipal religious and sacred unknown tree fire wood shorea robusta sal timber and religious mangifera indica l. mango multipurpose (fruit, timber, fuel wood, religious) arockiaraj et al. /journal of tropical forestry and environment vol. 5. no 02 (2015) 40-53 51 references agüera, f., aguilar, m.a. and aguilar, f.j. 2006. detecting greenhouse changes from quickbird imagery on the mediterranean coast. international journal of remote sensing, 27(21): 47514767. ajaz-ul-islam, m., quli, s.m.s., rai, r. and sofi, p.a. 2013. livelihood contributions of forest resources to the tribal communities of jharkhand. indian journal of fundamental and applied life sciences, 3(2): 131-144. arenas-castro, s., fernández-haeger, j. and jordano-barbudo, d. 2013. evaluation and comparison of quickbird and ads40-sh52 multispectral imagery for mapping iberian wild pear trees (pyrus bourgaeana, decne) in a mediterranean mixed forest. forests, 5: 1304-1330. arévalo, v., gonzález, j., valdes, j. and ambrosia, g. 2006. detecting shadows in quickbird satellite images.isprs commission vii mid-term symposium. enschede, the netherlands: 8-11 pp. brandtberg, t. 1998. automated delineation of individual tree crowns in high spatial resolution aerial images by multiple-scale analysis. machine vision and applications, 11: 64–73. census of india, 2001. population totals and data productsjharkhand 2001, government of india. census of india, 2011. population totals and data productsjharkhand 2011, government of india. crespi, m., de vendictis, l., grün, a., iannucci, g., poli, d., volpe, f. and wang, x. 2007. dsm extraction from quickbird and cartosat stereopairs: quality assessment and comparison. in: 8 th conference on optical 3d measurement techniques, zurich, switzerland, proceeding of the conference, 1: 195-203. culvenor, d.s., coops, n.c., preston, r. and tolhurst, k. 1999. a spatial clustering approach to automated crown delineation. in: proceedings of the forum on automated interpretation of high spatial resolution digital imagery for forestry. hill d.a. and d.g. leckie (eds.), 67-80. deadman, m.w. and goulding, c.j. 1979. a method for the assessment of recoverable volume by logtypes. new zealand journal of forestry science 9(1): 225-239. forest survey of india 2011. india state of forests report. dehradun, ministry of environment & forest, government of india. frick, a., weyer, g., kenneweg, h. and kleinschmit, b. 2005. a knowledge-based approach to vegetation monitoring with quickbird imagery. isprs workshop 2005-high resolution earth imaging for geospatial information, hannover, 1-8. gordon, a.d., lawrence, m.e. and pont, d. 1995. assessing the potential log yield of stands prior to harvesting. in: proceedings of the institute of foresters of australia 16 th biennial conference on applications of new technologies in forestry. ballarat, victoria, 18-21 pp. gordon, a.d., wakelin, s.j. and threadgill, j.a. 2006. using measured and modelled wood quality information to optimise harvest scheduling and log allocation decisions. new zealand journal of forestry science, 36(2/3): 198–215. greenberg, j.a., dobrowsk, s.z. and usti, s.l. 2005. shadow allometry: estimating tree structural parameters using hyperspatial image analysis. remote sensing of environment, 97: 15-25. hall, r.j. and skakun, r.s. 2007. mapping forest inventory attributes across coniferous, deciduous and mixed wood stand types in the northwest territories from high spatial resolution quickbird satellite imagery. in: proceedings of our common borders – safety, security and the environment through remote sensing. american society for photogrammetry and remote sensing (asprs), 28 oct – 1 nov, 2007, ottawa, ontario, canada. irvin, r.b. and mckeown, d.m. 1989. methods for exploiting the relationship between buildings and their shadows in aerial imagery. ieee transactions on systems, man and cybernetics, 19(6): 1564–1575. 52 islam, s.t. and donoghue, d.n.m. 2004. an evaluation of quickbird data for assessing woodland resource in deciduous sal forests in bangladesh. in: remote sensing and photogrammetry society annual conference, [http://www.macaulay.ac.uk/workshop/ remotesensing2004/ st_full_paper.pdf] jensen, j.r. 1996. introductory digital image processing: a remote sensing perspective. prentice hall, new jersey, 225-232. lu, d., hetrick, s. and moran, e. 2011. impervious surface mapping with quickbird imagery, international journal of remote sensing, 32(9): 2519-2533. lyons, m., phinn, s. and roelfsema, c. 2011. integrating quickbird multi-spectral satellite and field data: mapping bathymetry, seagrass cover, seagrass species and change in moreton bay, australia in 2004 and 2007. remote sensing, 3: 42-64. maco, s.e. and mcpherson, e.g. 2002. assessing canopy cover over streets and sidewalks in street tree populations. journal of arboriculture, 28(6): 270-276. malik, m.s., kaushal, p. and sah, r.b. unpublished report. socio-economic upliftment of tribal communities in jharkhand through agroforestry based farming system, faculty of forestry, birsa agricultural university, ranchi. mather, p.m. 2004. computer processing of remotely-sensed images: an introduction (3 rd edition). chichester: wiley nag, p. and kudrat, m. 1998. digital remote sensing. concept publication: new delhi: 234 ozdemir, 2008. estimating stem volume by tree crown area and tree shadow area extracted from pan sharpened quickbird imagery in open crimean juniper forest. international journal of remote sensing, 29(19): 5643-5655. plantier,t., loureiro,m., marques, p. and caetano, m. 2006. spectral analysis and classification of ikonos images for forest cover characterization. in: proceedings of the 2 nd workshop of the earsel sig on land use and land cover: 260-268. pp. rouse, j.w., haas, r.h., schell, j.a. and deering, d.w. 1993. monitoring vegetation systems in the great plains with erts. in: proceedings of 3 rd erts symposium, nasa sp-351, greenbelt, dm: 309-317 pp. seiler, j.r. and mcbee, p.n. 1992. a rapid technique for the evaluation of mature tree crown growth. journal of arboriculture, 18(6): 325-328. shamshad, a., hussin, w.m.a., wan, and sanusi, s.a. 2004.comparison of different data fusion approaches for surface features extraction using quickbird images. international symposium on geoinformatics for spatial infrastructure development in earth and allied sciences 2004, hanoi, vietnam, 423-431. singh,p.k., singh, b.k. and singh, a. 2005. managing tree cover in yamunanagar district of haryana: a remote sensing and gis approach. journal of the indian society of remote sensing, 33(2): 219-225. sinha, h. and kumar, a. 2013. governance of commons and livelihood security, xavier institute of social service. ranchi, india. souci, j.w.s. 2008. innovative woody biomass resource assessment using multiple resolution satellite imagery and geobia technology, 2. [http://homepages.ucalgary.ca/~gjhay/ geobia/ proceedings/sessions/session8/6732_san_souci_proc.pdf.] http://www.macaulay.ac.uk/workshop/%20remotesensing2004/%20st_full_paper.pdf http://www.macaulay.ac.uk/workshop/%20remotesensing2004/%20st_full_paper.pdf http://homepages.ucalgary.ca/~gjhay/%20geobia/%20proceedings/sessions/session8/6732_san_souci_proc.pdf http://homepages.ucalgary.ca/~gjhay/%20geobia/%20proceedings/sessions/session8/6732_san_souci_proc.pdf arockiaraj et al. /journal of tropical forestry and environment vol. 5. no 02 (2015) 40-53 53 uddin, k. dhakal, m. and joshi, g. 2014. an optical high and medium spatial resolution approach for erosion-prone areas assessment in mustang, nepal. international journal of geosciences, 5: 383-393. wang, r., hu, y. and zhang, x. 2005. extraction of urban road network using quickbird pansharpened multispectral and panchromatic imagery. geomatica, 59(3): 263-273. wenbo, w., lijing, b. and yang, j.i. 2008. application of tm and sar images fusion for land monitoring in coal mining areas. the international archives of the photogrammetry, remote sensing and spatial information sciences, 37(b7): 1140. zhang, y. 2002. problems in the fusion of commercial high resolution satellite images as well as landsat 7 images and initial solutions. international archives of photogrammetry and remote sensing (iaprs), 34(4). sen and bhakat/ journal of tropical forestry and environment vol. 10 no. 01 (2020) 17-39 _____________________________________________ *correspondence: uudaysen@gmail.com tel: +91 9002524806 © university of sri jayewardenepura 17 floristic and phytoclimatic study of an indigenous small scale natural landscape vegetation of jhargram district, west bengal, india u.k. sen* and r.k. bhakat ecology and taxonomy laboratory, department of botany and forestry, vidyasagar university, west bengal, india date received: 29-09-2019 date accepted: 28-06-2020 abstract sacred groves are distinctive examples of biotic components as genetic resources being preserved in situ and serve as secure heavens for many endangered and endemic taxa. from this point of view, the biological spectrum, leaf spectrum and conservation status of the current sacred grove vegetation, sbt (swarga bauri than) in jhargram district of west bengal, india, have been studied. the area's floristic study revealed that sbt‟s angiosperms were varied and consisted of 307 species belonging to 249 genera, distributed under 79 families of 36 orders as per apg iv. fabales (12.05%) and fabaceae (11.73%) are the dominant order and family in terms of species wealth. biological spectrum indicates that the region enjoys “thero-chamae-cryptophytic” type of phytoclimate. with respect to the spectrum of the leaf size, mesophyll (14.05%) was found to be high followed by notophyll (7.84%), microphyll (7.19%), macrophyll (7.84%), nanophyll (6.86%), leptophyll (6.21%), and megaphyll (2.29%). the study area, being a sacred grove, it has a comparatively undisturbed status, and the protection of germplasm in the grove is based on traditional belief in the social system. keywords: biodiversity conservation, biological spectrum, leaf spectra, life-form, sacred grove 1. introduction sacred groves are indigenous small scale natural landscape of native vegetation kinds that are traditionally protected and managed by local populations. a range of taboos and prohibitions are used to preserve biodiversity in „sacred groves‟ (colding and folke, 1997, 2001; berkes, 2009). many of them are connected to the premises of tiny temples. these sacred groves comprise plant species that are endemic, rare and endangered. they are therefore natural nursery with rare, threatened and endemic plant species, many of which have vanished outside the groves from the region (colding and folke, 1997). local communities preserve and protect sacred groves because of their religious convictions and the related traditional rituals that run through several generations. they may consist of multi-species, multitier primary forests or a clump of trees, depending on the history of the vegetation (gokhale et al., 2011). according to hughes and chandran (1998), these groves are landscape segments comprising vegetation and other types of life and geographical characteristics that are delimited and protected by human communities, believing that maintaining them in a comparatively undisturbed state is an expression of human relationship with the divine or nature. such groves are often situated in biodiversityrich areas, ranging from a few trees to multi-acre forestland. adapting a plant to certain ecological circumstances determines a type of life; therefore, it is a significant feature of physiognomy that has been commonly used in vegetation assessment. it shows the macro and microclimate and human disturbances of a certain area (cain and castro, 1959). doi: https://doi.org/10.31357/jtfe.v10i1.4686 18 the word “biological spectrum” was suggested by raunkiaer (1934) to describe the distribution of life-form in a flora as well as the phytoclimate under which the prevailing life-forms developed.under this scheme, plant species can be divided into five primary groups, i.e., phanerophytes, chamaephytes, hemicryptophytes, cryptophytes and therophytes. the percentage of various life form classes put together is called as the biological spectrum. raunkiaer (1934) built a standard spectrum that could behave as a null model, compared to different spectra of life form. the standard spectrum of raunkiaer (1934) shows a phanerophytic community, and the deviation (from it) determines the habit's phytoclimate. the occurrence in separate areas of comparable biological spectra shows comparable climatic circumstances. thus, the differences between normal spectrum and biological spectrum life forms may point out which life form characterises the phytoclimate or vegetation. climatic types may be characterised by the prevailing plant life forms in the plant communities under a specific climatic regime (raunkiaer, 1934; cain, 1950; muller and ellenberg, 1974; saxena et al., 1982). the indian region's biological spectrum is linked to particular edaphic, altitude and climatic variables (meher-homji, 1964; rana et al., 2002; reddy et al., 2011; sen and bhakat, 2009, 2012; singh and gupta, 2015; sen, 2016, 2018; sen and bhakat, 2018, 2019a, b, c). studying life-form is therefore a significant component of the description of vegetation, ranking next to floristic structure (batalha and martins, 2004). therefore, the biological spectrum is helpful as an index of forest landscape health status. biological spectrum may set rules for a community's optimisation and eco-restoration when performed at regular intervals. life form may also be categorised using leaf size i.e., leptophylls, nanophyll, microphyll, notophyll, mesophyll, macrophyll and megaphyll. it has some justification for using a leaf size to characterise distinct kinds of vegetation based on percentages of the distinct leaf dimensions present. however, light intensity and soil conditions, especially nitrogen and phosphorus accessible; also have a significant impact on the size of the leaf even within the same genotype (cunningham et al., 1999). 2. materials and methods 2.1 study site a) the sacred grove the study was conducted in a forested sacred grove namely sbt on outer edge of a tribal dominated chhotopindara, ranijhor and dochakhuria villages along the south-western bank of a perennial rivulet palpala, under gidni block (latitude 22 o 26 / 00.09 // -22 o 26 / 01.48 // n and longitude 86 o 50 / 00.90 // -86 o 50 / 01.56 // e, average altitude 86.7 m asl) in jhargram district of west bengal, india (figure. 1, 2, 3). the grove houses a brick-made small temple and is spread over a 3.5 acre public land. the grove is located about 38 km southeast from district headquarters at jhargram town, located in the southern part of west bengal, india (figure. 1). it represents a 400-450-year-old relict forest patch consisting of evergreen, deciduous and semideciduous plants. after the eight days of annual paus sankranti (a ritual celebrated on the last day of the bengali month paus or middle of january) and every tuesday and saturday local people, both tribal and non-tribal of gidni and adjoining blocks, visit the grove and worship the deity. since the grove is an abode of deity, the entire area along with plants and other life forms is considered sacred. owing to this socio-cultural tag on the grove, local people do not cut or disturb the grove flora, thus strictly adhering to the taboos and ethics. sen and bhakat/ journal of tropical forestry and environment vol. 10 no. 01 (2020) 17-39 19 jhargram district covers an area of 3,037.64 km 2 and had a population of 1,136,548 in the 2011 census. 96.52% of the total population were rural and only 3.48% were urban population. 20.11% of the total population belonged to scheduled castes and 29.37% belonged to scheduled tribes. its population growth rate over the decade 2001-2011 was 10.9%. the literacy rate was 72% in 2011, where the male literacy rate was 81% and female at 64%. the sex ratio was 979 females per 1,000 males (anon, 2011). 2.2 field survey and data collection during the period from december 2012 to january 2019, the study area was carefully surveyed in various seasons to explore the botanical and social wealth. a short floristic study was conducted on the grounds of “spot identification”. samples of plants with flowers or fruits have been gathered for unknown plants. the samples were processed, maintained, poisoned and assembled on herbarium sheets using conventional and modern herbarium methods after collection (jain and rao, 1977). in the sacred grove, photographs were taken of some prevalent, locally rare, endemic and valuable plant species. herbarium sheets have been recognised by matching properly annotated materials available at vidyasagar university's herbarium. for identification purpose, different relevant catalogue (anderson, 1862), regional floras (hooker, 1872-1897; prain, 1903; haines, 1921-1925; bennet, 1979; sanyal, 1994), monographs (mitra, 1958), revisionary works (datta and majumdar, 1966) and other literature were consulted. the socio-cultural functions surrounding the grove were recorded through information collected by interviewing and cross-interviewing the local people. 2.3 analysis of vegetation in the systematic enumeration of the taxa; clade, order, family, species along with habit, lifespan, flowering and fruiting time, raunkiaer‟s life-form with sub-type, leaf spectra, iucn status (iucn, 2020) and distribution of the plants in the grove have been arranged according to angiosperm phylogeny group iv classification (chase et al., 2016) (table 1). all the species were categorised into various raunkiaer‟s life form categories depending on the position of regenerating parts or propagules in all the collected species. thus a biological spectrum was prepared for the grove that was subsequently compared with the raunkiaer‟s normal spectrum to determine the phytoclimate of the grove (raunkiaer, 1934; muller and ellenberg, 1974). the knowledge of leaf size helped us understand the physiological status of plants and the plant communities were useful in classifying the associations of plants. plants were divided into (a) leptophyll (<25 mm 2 ), (b) nanophyll (25-225 mm 2 ), (c) microphyll (225-2,025 figure 1. location of the study area. figure 2. google earth image showing sbt sacred. grove. figure 3. small temple in sbt sacred grove. 20 mm 2 ), (d) notophyll (2,025-4,500 mm 2 ), (e) mesophyll (4,500-18,225 mm 2 ), (f) macrophyll (18,225164,025 mm 2 ) and (g) megaphyll (>164,025 mm 2 ) (raunkiaer, 1934). 3. results and discussion 3.1 different plant taxa in the present study, a total of 307 species belonging to 249 genera distributed over 79 families under 36 orders (apg iv, 2016) were recorded from the sacred grove. the top two clades are rosids and asterids. more than 81% of the flora is represented by orders of eudicot and core eudicot, of which the major contributions in terms of descending species number (≥10 species) are from fabales 37 (12.05%), lamiales 36 (11.73%), gentianales 28 (9.12%), poales 28 (9.12%), malvales 20 (6.51%), asterales 17 (5.54%), malpighiales 17 (5.54%), myrtales 15 (4.89%), solanales 14 (4.56%), sapindales 13 (4.23%) and caryophyllales 12 (3.91%) (table 1, figure. 4). similar types of distribution of orders were highlighted by gnanasekaran et al., 2012; sen, 2016, 2018 and sen and bhakat, 2018, 2019a, b, c. figure 4. major contribution of orders (≥10 species) in the sbt. the fourteen well represented families in species (≥6 species), are: fabaceae 36 (11.73%), poaceae 20 (6.51%), malvaceae 19 (6.19%), apocynaceae 18 (5.86%), asteraceae 17 (5.54%), lamiaceae 15 (4.89%), acanthaceae 12 (3.91%), euphorbiaceae 9 (2.93%), rubiaceae 9 (2.93%), cyperaceae 8 (2.61%), solanaceae 8 (2.61%), amaranthaceae 6 (1.95%), combretaceae 6 (1.95%) and convolvulaceae 6 (1.95%) (table 1, figure. 5). cucurbitaceae, moraceae and phyllanthaceae comprised 5 (1.62%) species each. four families contained 4 (1.30%), eight families contained 3 (0.98%) and thirteen families covered 2 (0.65%) species. another 37 families each had only a single species (table 1). t o ta l n o . o f sp e c ie s dominant orders (≥10 species) figure 5. major contribution of families (≥6 species) in the sbt. total no. of the species n a m e o f th e f a m il ie s sen and bhakat/ journal of tropical forestry and environment vol. 10 no. 01 (2020) 17-39 21 same type dominant families of sacred groves in india were observed by rajendraprasad et al., 1998; ghildiyal et al., 2016; sen, 2016 etc. in the global context, such family dominance was shown by batalha and martins, 2004; badshah et al., 2016; chigani et al., 2017 etc. asteraceae, fabaceae and poaceae emerged as the common families in the investigated area. mendez (2005) also stated that the abundance of the same families in laguna (mendoza, argentina). the members of fabaceae and poaceae were dominant due to their distribution with wide ecological amplitude. 3.2 species diversity in different growth forms the present floristic study of the sacred grove showed that it harboured a total of 307 plant species [dicots 249 (81.11%) and monocots 58 (18.89%)] belonging to 249 genera [dicots 203 (81.53%) and monocots 46 (18.47%)] of 79 families [dicots 62 (78.48%) and monocots 17 (21.52%)] under 36 orders [dicots 27 (75%) and monocots 9 (25%)]. among these, 119 (38.76%) of the reported species were herbs followed by shrubs 63 (20.52%), trees 76 (24.76%) and climbers 49 (15.96%) respectively. amongst the total dicots 249 (81.11%) and monocots 58 (18.89%), herbs, shrubs, trees and climbers represented 79, 59, 70, 41 and 40, 4, 6, 8 species respectively, representing 25.73%, 19.22%, 22.80%, 13.36% and 13.03%, 1.30%, 1.95%, 2.61% of the total species (table 2, figure 6). figure 6. total angiosperm taxa. -50 0 50 100 150 200 250 300 orders families genera herbs species shrubs trees climber total t o ta l n o . o f sp e c ie s different angiosperm taxa 22 table 1: floristic list of sbt sacred grove. name of the species habit life-span fl. and fr. time raunkiaer‟s life-form sub-type leaf spectra iucn red list status piperales bercht. and j. presl aristolochiaceae juss. aristolochia indica l. c a jul.-jan. cr no ne magnoliales juss. ex bercht. and j. presl annonaceae juss. annona reticulata l. t p jul.-dec. ph n me ne annona squamosa l. t p mar.-sep. ph n me lc laurales juss. ex bercht. and j. presl lauraceae juss. litsea glutinosa (lour.) c. b. rob. t p apr.-sep. ph m ma lc independent lineage: unplaced to more inclusive clade alismatales r. br. ex bercht. and j. presl araceae juss. alocasia macrorrhizos (l.) g. don h p apr.-may cr me ne amorphophallus paeoniifolius (dennst.) nicolson h a jun.-dec. cr mg lc colocasia esculenta (l.) schott h a jul.-oct. cr mg lc scindapsus officinalis (roxb.) schott c p cr mg ne hydrocharitaceae juss. hydrilla verticillata (l. f.) royle h a nov.-mar. cr le lc dioscoreales mart. dioscoreaceae r. br. dioscorea alata l. c p aug.-dec. cr ma ne dioscorea bulbifera l. c p aug.-dec. cr ma ne dioscorea pentaphylla l. c p sep.-feb. cr me ne pandanales r. br. ex bercht. and j. presl pandanaceae r. br. pandanus odorifer (forssk.) kuntze s p jul.-may ph n ma lc liliales perleb colchicaceae dc. gloriosa superba l. c p jul.-sep. cr no lc smilacaceae vent. smilax ovalifolia roxb. ex d. don c p jun.-dec. ch me ne asparagales link orchidaceae juss. vanda tessellata (roxb.) hook. ex g. don h p apr.-jul. ph n no lc sen and bhakat/ journal of tropical forestry and environment vol. 10 no. 01 (2020) 17-39 23 hypoxidaceae r. br. name of the species habit life-span fl. and fr. time raunkiaer‟s life-form sub-type leaf spectra iucn red list status curculigo orchioides gaertn. h p aug.-oct. cr mi ne xanthorrhoeaceae aloe vera (l.) burm.f. h p dec.-feb. cr me ne amaryllidaceae j. st.-hil. crinum asiaticum l. h p aug.-oct. cr mg ne asparagaceae juss. agave americana l. s p sep.-mar. cr mg ne asparagus racemosus willd. c p aug.-dec. cr le ne yucca gloriosa l. s p nov.-jun. cr me ne arecales bromhead arecaceae bercht. and j. presl borassus flabellifer l. t p mar.-oct. ph mm mg en phoenix acaulis roxb. s p feb.-jun. ch me ne phoenix sylvestris (l.) roxb. t p feb.-jun. ph m me ne commelinales mirb. ex bercht. and j. presl commelinaceae mirb. commelina benghalensis l. h a aug.-nov. th mi lc murdannia nudiflora (l.) brenan h a jul.-nov. th na ne zingiberales griseb. costaceae nakai cheilocostus speciosus (j. koenig) c. d. specht h p jul.-sep. cr ma ne zingiberaceae martinov curcuma aromatica salisb. h p may-jun. cr ma ne kaempferia galanga l. h p may-jun. cr ma ne poales small cyperaceae juss. cyperus difformis l. h p jul.-nov. he le lc cyperus dubius rottb. h p sep.-dec. he le lc cyperus platystylis r. br. h p may-jun. he le ne cyperus rotundus l. h p sep.-dec. he le lc fimbristylis cymosa r. br. h p feb.-may he le lc fimbristylis dichotoma (l.) vahl h p aug.-oct. he le lc fimbristylis quinquangularis (vahl) kunth h p aug.-nov. he le lc rhynchospora colorata (l.) h. pfeiff. h p may-oct. he le ne poaceae barnhart aristida setacea retz. h p aug.-dec. he le ne 24 bambusa bambos (l.) voss t p jul.-feb. ph m me lc brachiaria reptans (l.) c. a. gardner and c. e. hubb. h a aug.-oct. he mi lc name of the species habit life-span fl. and fr. time raunkiaer‟s life-form sub-type leaf spectra iucn red list status chloris barbata (l.) sw. h p aug.-nov. he le ne chrysopogon aciculatus (retz.) trin. h p sep.-dec. he le ne chrysopogon zizanioides (l.) roberty h p jun.-oct. he le ne coix lacryma-jobi l. h a aug.-jan. he no ne cymbopogon citratus (dc.) stapf. h a oct.-dec. he le ne cynodon dactylon (l.) pers. h p all he le ne digitaria sanguinalis (l.) scop. h p mar.-jun. he le ne echinochloa crusgalli (l.) p. beauv. h a aug.-nov. he na lc echinochloa frumentacea link h a aug.-nov. he na lc eleusine indica (l.) gaertn. h p aug.-nov. he le lc eragrostis amabilis (l.) wight and am. h p aug.-feb. he le ne eragrostis ciliaris (l.) r. br. h p aug.-feb. he le ne imperata cylindrica (l.) raeusch. h p oct.-dec. he na lc paspalum scrobiculatum l. h p aug.-nov. he na lc pennisetum glaucum (l.) r. br. h p aug.-oct. he mi lc setaria glauca (l.) r. br. h p aug.-nov. he le ne sporobolus indicus (l.) r. br. h p aug.-nov. he na ne eudicots ranunculales juss. ex bercht. and j. presl papaveraceae juss. argemone mexicana l. h a dec.-apr. th ma ne menispermaceae juss. stephania japonica (thunb.) mier. c p jul.-dec. ph n me ne tinospora sinensis (lour.) merr. c p feb.-jun. ph n me ne core eudicots superrosids saxifragales bercht. and j. presl crassulaceae j. st. -hil. bryophyllum pinnatum (lam.) oken h p mar.-jun. ch ma ne rosids vitales juss. ex bercht. and j. presl vitaceae juss. ampelocissus latifolia (roxb.) planch. c p jun.sep. ph n me ne cayratia trifolia (l.) domin. c p aug.-dec. ph n no ne cissus quadrangularis l. c p jul.-jan. ph n no ne sen and bhakat/ journal of tropical forestry and environment vol. 10 no. 01 (2020) 17-39 25 leea asiatica (l.) ridsdale c p jul.-sep. ph n me ne zygophyllales link zygophyllaceae r. br. name of the species habit life-span fl. and fr. time raunkiaer‟s life-form sub-type leaf spectra iucn red list status tribulus terrestris l. c a feb.-sep. th na lc fabales bromhead fabaceae lindl. abrus precatorius l. c p aug.-mar. ph n na ne acacia pennata (l.) willd. t p feb.-oct ph m na lc acacia polyacantha willd. t p feb.-oct ph m na lc acacia rugata (lam.) fawc. and rendle t p feb.-oct ph m na ne acacia auriculiformis benth. t p feb.-oct. ph m me lc acacia nilotica (l.) delile t p jun.-sep. ph m na lc adenanthera pavonina l. t p mar.-jan. ph m no lc albizia lebbeck (l.) benth. t p mar.-feb. ph mm mi ne albizia saman (jacq.) merr. t p mar.-feb. ph mm me ne bauhinia vahlii wight and arn. c p apr.-feb. ph n mg ne bauhinia variegate l. t p feb.-jun. ph m me lc butea superba roxb. c p feb.-jul. ph m ma ne caesalpinia pulcherrima (l.) sw. t p mar.-sep. ph m mi lc caesalpinia bonduc (l.) roxb. c p aug.-apr. ph n mi lc caesalpinia globulorum bakh. f. and p. royen c p mar.-sep. ph n mi ne cajanus scarabaeoides (l.) thouars c a sep.-feb. ph n mi lc clitoria ternatea l. c a all ph n no ne codariocalyx motorius (houtt.) h. ohashi s a aug.-dec. ch na ne crotalaria pallida aiton s a aug.-jan. ch no ne crotalaria prostrata willd. h a aug.-jan. th no ne derris indica (lam.) bennet c p jul.-jan. ph n na ne flemingia strobilifera (l.) w. t. aiton h a feb.-sep. ch me ne indigofera tinctoria l. h b aug.-nov. th mi ne mimosa pudica l. h p jul.-nov. th na lc mimosa rubicaulis lam. s p jul.-nov. ch na ne mucuna pruriens (l.) dc. c a sep.-may ch le ne parkinsonia aculeate l. t p oct.-jun. ph n mi lc peltophorum pterocarpum (dc.) k. heyne t p mar.-jan. ph mm mi ne pongamia pinnata (l.) pierre t p apr.-feb. ph m me lc senna alata (l.) roxb. s a aug.-nov. ch ma lc senna occidentalis (l.) link s p aug.-dec. ch no ne 26 senna tora (l.) roxb. h a sep.-dec. th mi ne sesbania sesban (l.) merr. s p dec.-apr. ch ma lc tamarindus indica l. t p apr.-jan. ph mm na lc tephrosia purpurea (l.) pers. h p sep.-dec. th na lc name of the species habit life-span fl. and fr. time raunkiaer‟s life-form sub-type leaf spectra iucn red list status zornia gibbosa span. h a aug.-nov. th na ne polygalaceae hoffmanns. and link polygala arvensis willd. h a jul.-dec. th me ne rosales bercht. and j.presl rhamnaceae juss. ventilago denticulata willd. c p sep.-jun. ph n me ne ziziphus jujube mill. t p sep.-mar. ph m no lc ziziphus oenopolia (l.) mill. c p nov.-mar. ph n no lc ulmaceae mirb. holoptelea integrifolia planch t p jan.-jun. ph mm me ne moraceae gaudich. artocarpus heterophyllus lamk. t p jan.-aug. ph m ma ne ficus benghalensis l. t p mar.-sep. ph mm ma ne ficus religiosa l. t p jun.-aug. ph mm ma ne ficus racemose l. t p mar.-aug. ph m ma lc streblus asper lour. t p feb.-jun. ph n mi lc cucurbitales juss. ex bercht. and j. presl cucurbitaceae juss. cayaponia laciniosa (l.) c. jeffrey c a jun.-jan. ph n mi ne coccinia grandis (l.) voigt c p mar.-dec. ph n me ne momordica dioica roxb. ex willd. c a aug.-dec. ph n me ne trichosanthes cucumerina l c p aug.-dec. ph n me ne trichosanthes tricuspidata lour. c a apr.-sep. ph n me ne celastrales link celastraceae r. br. celastrus paniculatus willd. c p apr.-dec. ph n me ne oxalidales bercht. and j. presl oxalidaceae r.br. averrhoa carambola l. t p feb.-sep. ph n ma ne oxalis corniculata l. h a all th na ne malpighiales juss. ex bercht. and j. presl clusiaceae lindl. garcinia xanthochymus hook. f. ex t. anderson t p mar.-jan. ph m no ne sen and bhakat/ journal of tropical forestry and environment vol. 10 no. 01 (2020) 17-39 27 violaceae batsch hybanthus enneaspermus (l.) f. muell. h p jul.-nov. th na ne salicaceae mirb. flacourtia indica (burm. f.) merr. s p sep.-may. ch mi lc name of the species habit life-span fl. and fr. time raunkiaer‟s life-form sub-type leaf spectra iucn red list status euphorbiaceae juss. acalypha indica l. h a all th no ne croton bonplandianus baill. h p all th no ne euphorbia antiquorum l. t p jan.-apr. ph n le ne euphorbia hirta l. h a feb.-dec. th na ne euphorbia neriifolia l. s p oct.-feb. ch le ne jatropha curcas l. s p mar.-aug. ch ma ne jatropha gossypifolia l. s p mar.-aug. ch ma ne ricinus communis l. s p jan.-apr. ph n mg ne tragia involucrata l. c p mar.-jan. ph n me ne phyllanthaceae martinov antidesma acidum retz. t p jun.-dec. ph n me lc breynia vitis-idaea (burm. f.) c. e. c. fisch. s p apr.-dec. ph n mi lc bridelia retusa (l.) a. juss. t p mar.-dec. ph n me lc phyllanthus amarus schumach. and thonn. h a apr.-sep. th na ne phyllanthus virgatus g. forst. h a apr.-sep. th na ne myrtales juss. ex bercht. and j. presl combretaceae r. br. combretum album pers. c p nov.-may ph n me ne combretum decandrum jacq. c p nov.-may ph n me ne combretum indicum (l.) de filipps c p all ph n me ne terminalia arjuna (roxb. ex dc.) wight and arn. t p apr.-feb. ph mm ma ne terminalia bellirica (gaertn.) roxb. t p apr.-feb. ph mm ma ne terminalia tomentosa (roxb.) wight and arn. t p apr.-may ph mm ma ne lythraceae j.st.-hil. ammannia baccifera l. h a sep.-feb. th le lc lawsonia inermis l. s p oct.-dec. ph n na ne punica granatum l. s p mar.-oct. ph n na lc rotala densiflora (roth) koehne h a aug.-nov. th le lc onagraceae juss. ludwigia octovalvis (jacq.) p. h. raven h a sep.-jan. th mi lc myrtaceae juss. 28 eucalyptus tereticornis sm. t p mar.-jul. ph mm me ne psidium guajava l. t p apr.-oct. ph n me lc syzygium cumini (l.) skeels t p mar.-jul. ph mm me lc melastomataceae juss. melastoma malabathricum l. s p may-jan. ch me ne name of the species habit life-span fl. and fr. time raunkiaer‟s life-form sub-type leaf spectra iucn red list status sapindales juss. ex bercht. and j. presl anacardiaceae r. br. lannea coromandelica (houtt.) merr. t p feb.-jun. ph m mg ne mangifera indica l. t p feb.-jun. ph m ma dd semecarpus anacardium l. f. t p jul.-dec. ph m mg ne sapindaceae juss. cardiospermum halicacabum l. c a jul.-dec. ph n no ne sapindus emarginatus vahl t p dec.-may ph m me ne schleichera oleosa (lour.) merr. t p mar.-jul. ph mm ma lc rutaceae juss. aegle marmelos (l.) corrêa t p may-jul. ph m me ne glycosmis pentaphylla (retz.) dc. t p sep.-feb. ph n me lc limonia acidissima groff t p jan.-dec. ph m na ne murraya koenigii (l.) spreng. t p apr.-jun. ph n na ne simaroubaceae dc. ailanthus excelsa roxb. t p jan.-jun. ph mm ma ne meliaceae juss. azadirachta indica a. juss. t p mar.-jul. ph m no lc melia azedarach l. t p feb.-nov. ph m no lc malvales juss. ex bercht. and j. presl malvaceae juss. abelmoschus crinitus wall. s a mar.-sep. ch no ne abelmoschus moschatus medik. s a mar.-aug.. ch no ne abutilon indicum (l.) sweet s a jun.-dec. ch ma ne ambroma augusta l. f. s p jan.-mar. ph n ma ne azanza lampas (cav.) alef. s a sep.-dec. ch ma ne corchorus aestuans l. h a jul.-nov. th me ne gossypium arboreum l. s p aug.-feb. ch ma nt gossypium barbadense l. s p dec.-apr. ch ma lc grewia helicterifolia wall, ex g. don t p jun.-sep. ph n ma ne grewia asiatica l. t p jun.-aug. ph n me lc helicteres isora l. s p sep.-feb. ph n me ne hibiscus rosa-sinensis l. s p all ch me ne sen and bhakat/ journal of tropical forestry and environment vol. 10 no. 01 (2020) 17-39 29 hibiscus vitifolius l. s a oct.-feb. ch me ne pterospermum acerifolium (l.) willd. t p jan.-aug. ph mm ma ne sida acuta burm. f. s a aug.-dec. th no ne sida cordata (burm.f.) borss. waalk. h a aug.-feb. th no ne sida cordifolia l. s a aug.-dec. th no ne triumfetta rhomboidea jacq. s a sep.-jan. th me ne name of the species habit life-span fl. and fr. time raunkiaer‟s life-form sub-type leaf spectra iucn red list status urena sinuata l. s a sep.-dec. ch no ne bixaceae kunth bixa orellana l. t p oct.-mar. ph n me lc brassicales bromhead capparaceae juss. capparis zeylanica l. c p mar.-oct. ph m no ne crateva nurvala buch.-ham. t p mar.-jul. ph m me ne cleomaceae bercht. and j. presl cleome gynandra l. h a jul.-sep. th no ne cleome viscosa l. h a sep.-apr. th no ne superasterids santalales r. br. ex bercht. and j. presl santalaceae r. br. viscum cruciatum sieber ex boiss. s p jan.-jun. ph n le ne loranthaceae juss. loranthus cordifolius wall. s a jul.-nov. ph n no ne scurrula atropurpurea (blume) danser s a nov.-mar. ph n no ne caryophyllales juss. ex bercht. and j. presl droseraceae salisb. drosera burmanni vahl h a nov.-apr. th le lc amaranthaceae juss achyranthes aspera l. h a sep.-feb. th mi ne aerva lanata (l.) juss. h a nov.-jan. th le ne alternanthera sessilis (l.) r. br. ex dc. h a jul.-feb. th mi lc amaranthus spinosus l. h a all th na ne amaranthus viridis l. h a all th na ne celosia argentea l. h a sep.-feb. th na ne aizoaceae martinov trianthema portulaccastrum l. h a apr.-oct. th mi ne nyctaginaceae juss. boerhavia diffusa l. h a jun.-dec. th mi ne 30 portulacaceae juss. portulaca oleracea l. h a jun.-dec. th mi ne cactaceae juss. cereus pterogonus lam. s p jun.-jul. ch le ne opuntia stricta (haw.) haw. s p apr.-aug. ch le lc asterids name of the species habit life-span fl. and fr. time raunkiaer‟s life-form sub-type leaf spectra iucn red list status cornales link cornaceae bercht. and j. presl alangium salviifolium (l. f.) wangerin t p mar.-jul. ph n me ne ericales bercht. and j. presl lecythidaceae a. rich. careya arborea roxb. t p jan.-apr. ph m mg ne sapotaceae juss. madhuca longifolia var latifolia (roxb.) a. chev. t p mar.-jul. ph mm ma ne mimusops elengi l. t p apr.-sep. ph mm me lc ebenaceae gurke diospyros melanoxylon roxb. t p apr.-jul. ph mm ma ne gentianales juss. ex bercht. and j. presl rubiaceae juss. gardenia gummifera l. f. t p mar.-aug. ph n no lc gardenia resinifera roth s p feb.-jun. ph n no ne haldina cordifolia (roxb.) ridsdale t p jun.-dec. ph mm ma ne hedyotis neesiana arn. h a jun.-nov. th na ne meyna spinose roxb. ex link s p mar.-jun. ch me ne morinda citrifolia l. t p feb.-may ph n ma ne neolamarckia cadamba (roxb.) bosser t p jul.-nov. ph mm ma ne oldenlandia corymbosa l. h a aug.-feb. th le lc spermacoce articularis l. f. h a all th na ne loganiaceae r.br. ex mart. strychnos nux-vomica l. t p mar.-jan. ph mm me ne apocynaceae juss. alstonia scholaris (l.) r. br. t p nov.-aug. ph mm me lc calotropis gigantean (l.) dryand. s p mar.-feb. ch ma ne carissa spinarum a. dc. c p mar.-oct. ph n no ne cascabela thevetia (l.) lippold t p all ph n mi lc catharanthus roseus (l.) g. don. s p all th no ne sen and bhakat/ journal of tropical forestry and environment vol. 10 no. 01 (2020) 17-39 31 cryptolepis dubia (burm.f.) m.r.almeida c p apr.-mar. ph n no ne gymnema sylvestre (retz.) r.br. ex sm. c p apr.-mar. ph n mi ne hemidesmus indicus (l.) r. br. ex schult. c p aug.-jan. ph n mi ne holarrhena pubescens wall. ex g. don t p apr.-feb. ph n ma lc ichnocarpus frutescens (l.) w. t. aiton s p sep.-mar. ph n no ne marsdenia sylvestris (retz.) p. l. forst. c p apr.-mar. ph n mi ne nerium oleander (l.) s p jul.-apr. ph n no lc name of the species habit life-span fl. and fr. time raunkiaer‟s life-form sub-type leaf spectra iucn red list status pergularia daemia (forssk.) chiov. c p sep.-jan. ph n me ne plumeria rubra (l.) t p oct.-may ph m no lc rauvolfia serpentina (l.) benth. ex kurz s p mar.-dec. th me ne rauvolfia tetraphylla l. s p feb.-dec. ch no ne tylophora indica (burm. f.) merr. c a apr.-oct. ph n no ne vallaris solanacea (roth) kuntze c p apr.-jan. ph n me ne boraginales juss. ex bercht. and j. presl boraginaceae juss. heliotropium indicum l. h a oct.-jan. th no ne solanales juss. ex bercht. and j. presl convolvulaceae juss. cuscuta reflexa roxb. c p nov.-mar. ph n ap ne evolvulus alsinoides (l.) l. h a jul.-feb. th na ne ipomoea aquatica forssk. h p all th no lc ipomoea mauritiana jacq, c p aug.-dec. ph n ma ne jacquemontia paniculata (burm. f.) hallier f. t p sep.-jan. ph n mi ne rivea hypocrateriformis choisy c p aug.-oct. ph n no ne solanaceae juss. datura metel l. s p aug.-may ch ma ne datura stramonium l. s p jul.-oct. ch ma ne physalis minima l. h a aug.-dec. ch ma ne solanum americanum mill. h a dec.-jun. th ma ne solanum rudepannum dunal h a dec.-jun. th ma lc solanum surattense burm. f. h a aug.-dec. th ma ne solanum torvum sw. h p jul.-mar. ch ma ne solanum virginianum l. h a dec.-jun. th ma ne lamiales bromhead oleaceae hoffmanns. and link nyctanthes arbor-tristis l. t p sep.-jan. ch mi ne plantaginaceae juss. 32 bacopa monnieri (l.) pennell h a apr.-jan. th na lc limnophila indica (l.) druce h a sep.-jan. th na lc scoparia dulcis l. h a may-dec. th na ne martyniaceae horan. martynia annua l. h a aug.-dec. ch me ne acanthaceae juss. andrographis echioides (l.) nees h a jul.-oct. th no ne andrographis paniculata (burm. f.) nees h a sep.-apr. th no ne name of the species habit life-span fl. and fr. time raunkiaer‟s life-form sub-type leaf spectra iucn red list status barleria lupulina lindl. s p dec.-apr. ch mi ne barleria prionitis (l.) s p dec.-apr. ch mi ne dicliptera bupleuroides nees h a jun.-oct. th no ne ecbolium viride (forsk.) alston h p dec.-apr. ch mi ne hemigraphis hirta t. anders. h a aug.-nov. th mi ne hygrophila auriculata (schumach.) heine h a sep.-jan. th mi lc justicia adhatoda l. s p feb.-apr. ch me ne justicia gendarussa burm.f. s p feb.-apr. ch me ne ruellia tuberosa l. h a aug.-nov. th mi ne rungia pectinata (l.) nees h a all th mi ne bignoniaceae juss. tecoma stans (l.) juss. ex kunth t p nov.-mar. ph n me ne stereospermum chelonoides (l. f.) dc. t p aug.-feb. ph m me ne verbenaceae j. st. hil. lantana camara (l.) s p nov.-feb. ch no ne lippia javanica (burm. f.) spreng. s p sep.-apr. ch mi ne lamiaceae martinov anisochilus carnosus (l. f.) wall. s a sep.-jan. ch no ne anisomeles indica (l.) kuntze h a sep.-jan. ch mi ne clerodendrum infortunatum l. s p feb.-jul. ch ma ne hyptis suaveolens (l.) poit. s a sep.-jan. ch me ne leonotis nepetifolia (l.) r. br. s a apr.-jul. th me ne leonurus sibiricus l. s a sep.-feb. ch mi ne leucas cephalotes (roth) spreng. h a sep.-dec. th mi ne mentha longifolia (l.) l. s a apr.-jul. th mi lc ocimum americanum l. s p all ch na ne ocimum basilicum l. h p may-jul. ch na ne ocimum tenuiflorum l. s p aug.-jan. ch na ne plectranthus amboinicus (lour.) spreng. h a may-sep. th mi ne sen and bhakat/ journal of tropical forestry and environment vol. 10 no. 01 (2020) 17-39 33 premna mollissima roth t p may-jul. ph m no ne tectona grandis l. f. t p jul.-jan. ph mm mg ne vitex negundo l. t p mar.-jun. ph n mi lc asterales link asteraceae bercht. and j.presl ageratum conyzoides (l.) l. h a nov.-mar. th mi lc ayapana triplinervis (vahl) r. m. king and h. rob. h a aug.-dec. th mi ne name of the species habit life-span fl. and fr. time raunkiaer‟s life-form sub-type leaf spectra iucn red list status baccharoides anthelmintica (l.) moench h a sep.-mar. th me ne blumea lacera (burm.f.) dc. h a aug.-feb. th mi ne chromolaena odorata (l.) r. m. king and h. rob. s a mar.-sep. ch mi ne cyanthillium albicans (dc.) h. rob. h a aug.-mar. th mi ne cyanthillium cinereum (l.) h. rob. h a nov.-feb. th me ne eclipta prostrata (l.) l. h a all th mi lc elephantopus scaber l. h a sep.-jan. th no ne enydra fluctuans dc. h a dec.-mar. th mi lc grangea maderaspatana (l.) poir. h a dec.-may th le lc sonchus oleraceus (l.) l. h a sep.-jan. th na ne sphaeranthus senegalensis dc. h a nov.-apr. th le lc sphagneticola calendulacea (l.) pruski h a all th me ne synedrella nodiflora (l.) gaertn. h a sep.-jan. th no ne tridax procumbens (l.) l. h a all th na ne xanthium strumarium l. h a sep.-apr. th me ne apiales nakai apiaceae lindl. centella asiatica (l.) urb. h a jul.-jan. th no lc abbreviation in habit: c-climber; h-herb; s-shrub; t-tree in life-span: a-annual; b-biennial; p-perennial in flowering and fruiting time: jan.-january; feb.-february; mar.-march; apr.-april; jun.-june; jul.-july; aug.-august; sep.-september; oct.-october; nov.november; dec.-december; all-all season in raunkiaer’s life-form and sub-type: ch-chamaephytes; cr-cryptophytes; he-hemicryptophytes; m-mesophanerophyte; mm-megaphanerophytes; nnanophanerophytes; ph-phanerophytes; th-therophytes in leaf spectra: ap-aphyllous; le-leptophyll; na-nanophyll; mi-microphyll; no-notophyll; me-mesophyll; ma-macrophyll; mg-megaphyll in iucn red list status: dd-data deficient; lc-least concern; ne-not evaluated; vu-vulnerable; nt-near threatened 34 table 2: total angiospermic taxa. group orders families genera species herbs shrubs trees climber total dicots 27 62 203 79 59 70 41 249 monocots 9 17 46 40 4 6 8 58 total 36 79 249 119 63 76 49 307 3.3 life span in the sacred grove, 109 (35.50%) annual plants would go through their life cycle in one growing season. as many as 1 (0.33%) biennial plant whose life cycle spans two years. as many as 197 (64.17%) perennial plants that could survive most unfavorable conditions and stayed alive for more than two years (table 1). 3.4 life form and biological spectrum the biological spectrum shows that phanerophytes 128 (41.69%) was the dominant, followed by therophytes 81 (26.38%), chamaephytes 52 (16.95%), hemicryptophytes 27 (8.79%), and cryptophytes 19(6.19%). of the phanerophytes, nanophanerophytes 73 (23.78%) was dominant than mesophanerophytes 31 (10.10%) and megaphanerophytes 24 (7.82%) (table 3, figure 7). it reveals that therophytes, chamaephytes, and cryptophytes constituted the higher percentage 13.38%, 7.95% and 0.19% respectively than the normal spectrum exhibiting “thero-chamae-cryptophytic” phytoclimate. further, the number of hemicryptophytes (17.21%) and phanerophytes (4.31%) was comparatively smaller in percentage than the raunkiaer‟s normal spectrum. of the phanerophytes, nanophanerophytes (8.78%) and megaphanerophytes (4.82%) were somewhat larger and mesophanerophyte (17.9%) was a comparatively smaller value than the raunkiaer‟s normal spectrum (table 3, figure 7). this result was probably due to the local protection under certain taboos of the sacred grove. the dominant therophytes, chamaephytes, and cryptophytes altogether constituted 49.52% of the life forms proportion. therophytes showed the maximum divergence of the normal spectrum; other workers had also reported a similar phytoclimatic association for different tracks of vegetation (misra et al., 1979; saxena et al., 1982; rajendraprasad et al., 1998; sen, 2018). the dominance of therophytes (81 species, 26.38%) indicates that the investigated area was under mild biotic pressure (sher et al., 2014). many plant species were decreasing in the area. it would be the moral and ethical duty of the local people to protect the plant resources. table 3: biological spectrum (% of all life forms) of study site and its comparison with raunkiaer‟s normal spectrum. life forms total no. of species biological spectrum (%) of the study site raunkiaer‟s normal spectrum (%) deviation=(raunkiaer‟s normal spectrum biological spectrum) phanerophytes (ph) 128 41.69 46.00 -4.31 megaphanerophytes (mm) 24 7.82 3.00 4.82 mesophanerophytes (m) 31 10.10 28.00 -17.90 nanophanerophytes (n) 73 23.78 15.00 8.78 chamaephytes (ch) 52 16.95 9.00 7.95 hemicryptophytes (he) 27 8.79 26.00 -17.21 cryptophytes (cr) 19 6.19 6.00 0.19 therophytes (th) 81 26.38 13.00 13.38 total 307 100.00 100.00 sen and bhakat/ journal of tropical forestry and environment vol. 10 no. 01 (2020) 17-39 35 figure 7. comparison of biological spectrum with raunkiaer‟s normal spectrum. 3.5 leaf size spectra the overall leaf size spectra showed that there were leptophyll 34 (11.11%), nanophyll 42 (13.73%), microphyll 50 (16.34%), notophyll 52 (16.99%), mesophyll 67 (21.90%), macrophyll 49 (16.01%) and megaphyll 12 (3.92%). cuscuta reflexa is only aphyllous species. as regards the leaf size spectra, mesophyll was found to be high followed by notophyll, microphyll, macrophyll, nanophyll, leptophyll, and megaphyll (table 1, 4). in case of leaf spectra, the presence of leptophyll 19 (6.21%), nanophyll 21 ( 6.86%), microphyll 22 (7.19%), notophyll 24 (7.84%), mesophyll 43 (14.05%), macrophyll 24 (7.84%) and megaphyll 7 (2.29%) have the maximum in comparison to hemicryptophytes, therophytes, therophytes, phanerophytes, phanerophytes, phanerophytes and phanerophytes respectively (table 4). cyperaceae 8 (2.61%), poaceae 5 (1.63%), fabaceae 9 (2.93%), apocynaceae 8 (2.61%), malvaceae 6 (1.95%), solanaceae 8 (2.61%) and araceae 3 (0.98%) were dominant families of leptophyll, nanophyll, microphyll, notophyll, mesophyll, macrophyll and megaphyll respectively (table 4, figure 8). this result was also similar to other tropical forests in asia (bohman, 2004; gillison, 2018). table 4: life-form analysis with different leaf size. abbreviation in raunkiaer’s life-form: ch-chamaephytes; cr-cryptophytes; he-hemicryptophytes; m-mesophanerophyte; mmmegaphanerophytes; n-nanophanerophytes; ph-phanerophytes; th-therophytes raunkiaer‟s life form leaf spectra total ap le na mi no me ma mg ph 1 2 11 16 24 43 24 7 128 mm 1 2 7 12 2 24 m 5 1 8 9 5 3 31 n 1 2 5 13 16 27 7 2 73 ch 4 5 9 8 11 15 52 he 19 5 2 1 27 cr 2 1 2 4 5 5 19 th 7 21 22 17 9 5 81 total 1 34 42 50 52 67 49 12 307 0 10 20 30 40 50 60 ph ch he cr th o f p la n t sp e c ie s% raunkiaer's life form biological spectrum (%) of the study site raunkiaer‟s normal spectrum (%) 36 in leaf spectra: ap-aphyllous; le-leptophyll; na-nanophyll; mi-microphyll; no-notophyll; me-mesophyll; mamacrophyll; mg-megaphyll figure. 8. analysis of life form with different leaf size. 3.6 conservation status and iucn categories among these 307 plant species, 220 plants have not been evaluated still now. there were 85 least concerned (lc), 1 data deficient (dd), 1 near threatened (nt) species according to the iucn (iucn, 2020) (table 1). based on the above-mentioned phytosociological analysis with ecological information on iucn red listed plants, it is revealed that plants are still present and regenerate in the sacred grove but locally disappear in highly disturbed areas. this study would highlight the status and distribution of the species in the study area, the ecological characteristics necessary for their survival, and the threats to some of the species identified by following the iucn (2020) criteria. it is because iucn red list applications are a global plant diversity barometer (brummitt et al., 2008). various factors caused the increase in numbers of threatened species in the area. grasing was a major cause which led to the destruction of seedlings. the most critical factor that caused the decline of the endemic useful species was human activity, such as pilgrimage, dying of the plant and land use change. 4. conclusion the current study indicates the option of using raunkiaer's strategy to ascertain the notable differences between the populations of angiosperm plants in a forested landscape or biome and their associations, the part of species in the percentage of floristic life-forms that resulted by the existing ecological parameters and environmental gradients. life-form analysis provides a clear image of the sacred grove's biological spectrum. in the present study therophytes, chamaephytes and cryptophyte share the importance depicting the “thero-chamae-cryptophytic” phytoclimate. it may also be noted that the information acquired from this study will in future serve as a database of life forms for research of change detection and tenacity of bioclimate or phytoclimate (raju et al., 2014). comparing and contrasting the neighboring natural strands pattern along the environmental gradients will also be useful, revealing more than the mere forest covers in the ecosystem data; suggesting that biotic variables play a significant part in shaping a landscape's vegetation by guiding succession. this shows the impact in the 0 10 20 30 40 50 60 70 80 ap leaf spectra le na mi no me ma mg r a u n k ia e r' s li fe f o rm leaf spectra ph ch he cr th sen and bhakat/ journal of tropical forestry and environment vol. 10 no. 01 (2020) 17-39 37 sacred grove of anthropogenic disturbances that favor the development of more therophytes. further disruption to the current sacred grove can therefore promote future changes in its current phytoclimate. acknowledgement the authors are indebted to the informants and local tribal communities for cooperating and sharing their knowledge. without their contribution, this study would have been impossible. references anderson, t., 1862. catalogue of plants indigenous in the neighbourhood of calcutta with directions for examination and preservation of plants, calcutta, india. anon, 2011. district human development report, paschim medinipur, government of west bengal, development and planning department, 306. badshah, l., hussain, f. and sher, z., 2016. floristic inventory, eco-logical characteristics and biological spectrum of plants of parachinar, kurram agency, pakistan. pakistan journal of botany, 48:1547-1558. batalha, m.a. and martins, f.r., 2004. floristic, frequency, and vegetation life-form spectra of a cerrado site. brazilian journal of biology, 64:201-209. bennet, s.s.r., 1979. flora of howrah district, dehradun, india, international book distributors, 406. berkes, f., 2009. community conserved areas: policy issues in historic and contemporary context. conservation letters, 2:20-25. bohman k., 2004. functional and morphological diversity of trees in different land use types along a rainforest margin in sulawesi. [ph.d. thesis] indonesia, gottingen, university of gottingen. brummitt, n., bachman, s.p. and moat, j., 2008. applications of the iucn red list: towards a global barometer for plant diversity. endanger species research, 6:127-135. cain, s.a. and castro, g.d.o., 1959. manual of vegetation analysis, new york, usa, harper and brothers, 325. cain, s.a., 1950. life-form and phytoclimates. botanical review, 16:1-32. chase, m.w., christenhusz, m.j.m., fay, m.f., byng, j.w., judd, w.s., soltis, d.e., mabberley, d.j., sennikov, a.n., soltis, p.s. and stevens p.f., 2016. an update of the angiosperm phylogeny group classification for the orders and families of flowering plants: apg iv. botanical journal of linnaean society, 181:1-20. chigani, h.k., javadi, s.a., zahedi-amiri, g., khajeddin, s.j. and jafari, m., 2017. vegetation composition differentiation and species-environment relationships in the northern part of isfahan province. land degradation and development, 9:161-175. colding, j. and folke, c., 1997. the relations among threatened species, their protection, and taboos. conservation ecology, 1:6. colding, j. and folke, c., 2001. social taboos: “invisible” systems of local resource management and biological conservation. ecological applications, 11:584-600. cunningham, s.a., summerhayes, b. and westoby, m., 1999. evolutionary divergences in leaf structure and chemistry, comparing rainfall and soil nutrient gradients. ecological monographs, 69:569588. datta, s.c. and majumdar, n.c., 1966. flora of calcutta and vicinity. bulletin of botanical society of bengal, 20:16-120. ghildiyal, j.c., barthwal, n. and khantwal, a., 2016. life-forms and biological spectrum of deeva ka daanda a sacred grove in garhwal himalaya. indian forester, 142:167-178. gillison, a.n., 2018. latitudinal variation in plant functional types. in: geographical changes in vegetation and plant functional types, springer, cham, pp. 21-57. 38 gnanasekaran, g., nehru, p. and narasimhan, d., 2012. angiosperms of sendirakillai sacred grove (ssg), cuddalore district, tamil nadu, india. check list, 8:113-129. gokhale, y., pala, n.a., negi, a.k., bhat, j.a. and todaria, n.p., 2011. sacred landscapes as repositories of biodiversity: a case study from the hariyali devi sacred landscape, uttarakhand. international journal of conservation science, 2:37-44. haines, h.h., 1921-1925. the botany of bihar and orissa, vol 1-6 (reprint 1961), calcutta, india, botanical survey of india. hooker, j.d., 1872-1897. the flora of british india, vols. 1-7 (repr. 1973), dehra dun, india, bishen singh mahendra pal singh. hughes, j.d. and chandran, m.d.s., 1998. sacred groves around the earth: an overview. in: ramakrishnan, p.s., saxena, k.g., chandrashekara, u.m. (eds.), conserving the sacred for biodiversity management. oxford and ibh publ. co. pvt. ltd., new delhi, india, pp. 69-86. iucn, 2020. the iucn red list of threatened species. version 2020-1, https://www.iucnredlist.org. accessed 29 june 2020. jain s.k. and rao, r.r., 1977. a handbook of field and herbarium methods, today and tomorrow‟s printers and publishers, new delhi, india, 157. meher-homji, v.m., 1964. life forms and biological spectra as epharmonic criteria of aridity and humidity in tropics. journal of indian botanical society, 43:424-430. mendez, e., 2005. the vegetation of the laguna de llancanelo provincial reserve (mendiza, argentina). candollea, 60:123-148. misra, m.p., mishra, p.n. and pandey, b.n., 1979. an ecological account of the vegetation of brahmyoni hills (gaya). proceedings of the indian science congress, 3:108-109. mitra j.n., 1958. flowering plants of eastern india, vol. 01. monocotyledons, the world press private ltd., calcutta, 388. muller d. and ellenberg, h., 1974. aims and methods of vegetation ecology, john wiley and sons, new york, usa, p. 547. prain d., 1903. bengal plants, vol. 01 and 02, botanical survey of india, calcutta, india, p. 670. rajendraprasad, m., krishnan, p.n. and pushpangadan, p., 1998. the life form spectrum of sacred grove and a functional tool to analyse the vegetation. tropical ecology, 39:211-217. raju, v.s., krishna, p.g. and suthari, s., 2014. environmental assessment of climate of a habitat through floristic life-form spectra, a case study of warangal north forest division, telangana, india. journal of natural sciences, 2:77-93. rana, t.s., datt, b. and rao, r.r., 2002. life forms and biological spectrum of the flora of tons valley, garhwal himalaya (uttaranchal), india. taiwania, 47:164-169. raunkiaer c., 1934. the life forms of plants and statistical plant geography, clarendon press, oxford, p. 632. reddy, s.c., krishna, h.p., meena, s.l., bhardwaj, r. and sharma, k.c., 2011. composition of life forms and biological spectrum along climatic gradient in rajasthan, india. international journal of environmental science, 7:1632-1639. sanyal, m.n., 1994. flora of bankura district, bishen singh mahendra pal singh, dehra dun, india, p. 555. saxena, a.k., pandey, p. and singh, j.s., 1982. biological spectrum and other structural functional attributes of the vegetation of kumaun himalaya. plant ecology, 49:111-119. sen, u.k. and bhakat, r.k., 2009. ecological role of sacred groves in plant conservation. effects of environmental toxicology on human health, national environmental science academy, new delhi, india, pp. 211-219. sen and bhakat/ journal of tropical forestry and environment vol. 10 no. 01 (2020) 17-39 39 sen, u.k. and bhakat, r.k., 2012. sacred grove and plant conservation: an insight from taxonomy and ecology. in: maiti, g.g., mukherjee, s.k. (eds.), mutidisciplinary approaches in angiosperm systamatics. department of botany, university of kalyani, west bengal, india, pp. 410-421. sen, u.k. and bhakat, r.k., 2018. in situ conservation of a sacred grove in west midnapore district, west bengal, india: an integrated socio-ecological approach. journal of economic and taxonomic botany, 42:49-64. sen, u.k. and bhakat, r.k., 2019a. floristic and phytoclimatic study of a sacred grove vegetation of west midnapore district, west bengal, india. journal of tropical life science, 9:119-138. sen, u.k. and bhakat, r.k., 2019b. assessment of the floristic composition, biological spectrum, leaf size spectra and traditional conservation management of a sacred grove in west midnapore district, west bengal, india. indian forester, 145:156-171. sen, u.k. and bhakat, r.k., 2019c. floristic composition, biological spectrum and conservation status of a sacred grove from jhargram district, west bengal, india. indian journal of forestry, 42:161172. sen, u.k., 2018. assessing the social, ecological and economic impact on conservation activities within human-modified landscapes: a case study in jhargram district of west bengal, india. international journal of conservation science, 9:319-336. sen. u.k., 2016. botanical and socio-cultural studies on some sacred groves of west midnapore district, west bengal, ph.d. thesis, midnapore, india, vidyasagar university, p. 321. sher, z., hussain, f. and badshah, l., 2014. biodiversity and ecological characterization of the flora of gadoon rangeland, district swabi, khyber pukhtunkhwa, pakistan. iranian journal of botany, 20:96-108. singh, r.i. and gupta, a., 2015. life-form classification and biological spectrum of amambilok sacred grove, andro, manipur in northeast india. pleione, 9:356-364. 20 recommendations for co-existence of coral reef conservation and tourism at pigeon island national park n. perera 1* and s.w. kotagama 2 1 department of zoology, faculty of natural sciences, university of colombo, sri lanka 2 ministry of sustainable development and wildlife, government of sri lanka date received: 19-11-2015 date accepted: 15-03-2016 abstract pigeon islands national park (pinp) is one of the three marine national parks in sri lanka with coral reefs being the major habitat protected. a study was undertaken at pinp with the objective of understanding the challenges encountered and opportunities available for managing the park addressing both coral reef conservation and increasing tourism potential. field visits, formal and informal group discussions, expert opinions, web based information and literature surveys were the methodology utilized. despise the impose of an entrance fee in may 2011, 146,375 tourists visited the 471 ha park within 40 month period. pinp earned lkr 37,000 ha -1 in 2013 indicating that one hectare of coral reefs can earn more revenue than larger terrestrial parks with charismatic species such as elephants. foreign tourist arrivals had increased from 11.9% in 2011 to 25.13% by 2014. visitor reviews indicates that their experience was either excellent (46%) or very good (30%) due to abundance of marine life, while12% had either a poor or a terrible visitor experience at the site owing to overcrowding, reef damage and high price. with only 21% of live coral cover in 2013, it is evident that the reef is being degraded, indicating that a protected area which emphasizes on collecting user-fee revenues can lose sight of its primary conservation objectives and is not undertaking sustainable tourism. park management effectiveness is not at desirable level (43%), mainly due to non-implementation of a scientifically based management plan. a continuous monitoring programme to check the health of the reef is need, while the introduction of a multi-tiered user fee structures can enhance the economic reruns. incorporating pinp into wider seascape/landscape management through utilizing special area management approach with relevant stakeholder participation needed to be promoted. keywords: coral reefs, pigeon island national park, management effectiveness, sustainable tourism, stakeholders 1. introduction *correspondence: nmpperera@yahoo.com tel: + 94 779964451 issn 2235-9370 print/issn 2235-9362 online © university of sri jayewardenepura perera and kotagama /journal of tropical forestry and environment vol. 6. no 01 (2016) 20-35 21 pigeon island national park (pinp) is located 1 km off shore of the nilaveli beach, in the trincomalee district, sri lanka (8 0 45’0” n and 81 0 9’0” e to 8 0 36’0” n and 81 0 14’0” e). in 1974, 4.6 ha area consisting of the two islands were declared as a sanctuary under fauna and flora protection ordinance (ffpo) for the purpose of protecting the nationally endangered wild rock pigeons (columba livia), that colonize the rocky cliffs in large numbers. realizing the importance of protecting the adjoining healthy reef system, the islands together with the surrounding sea area within a one-mile radius was upgraded in to a national park in 2003 (iucn sl/cea, 2006; iucn, 2002). the park boundaries is measured at 1,000 m radius from the central point between the two islands and extend to 471.4 ha, while part of pinps buffer zone lies within the nilaveli beach, which is a popular tourist destination (figure 1). figure 1: location of the pigeon island national park. (prepared based on a map obtained from dwlc) pinp is one of out of the three marine national parks declared so far, the other two being the hikkaduwa and the adams bridge. available literature reveals that large scale destruction of coral reefs pinp occurred during the 1970s due to invasion of acanthaster planci (crown of thorn starfish – cots), but have since recovered, with branching and tabulate acropra spp being the dominant corals (de bruin, 1972; rajasuriya et al, 2005). to date, over 100 species of corals, and 222 species of reef fish have been identified, while three species of globally endangered marine turtles (eretmochelys imbricata, chelonia mydas and lepidochelys olivacea) are also recorded. the chetodon spp. are found in large numbers indicating that the reefs are not threatened by the 22 aquarium trade. these reefs were not affected by the 1998 coral bleaching event or damaged by the december 2004 tsunami, yet had suffered from reef walking, unregulated souvenir collection and the accumulation of solid waste (rajasuriya, 2005; iucn sl/cea, 2006; green tech, 2009). globally, coral reef associated tourism plays a major role in revenue earning and is estimated to provide around us $ 9.6 billion per year. reefs not only support niche sub-market in scuba diving and snorkeling excursions, they also add value to the tourism product through associated images of exoticism and natural beauty. in this context, it is no surprise that in many developing nations with reef resources, tourism is an alternative industry to develop. recreation can also pose distinct but potentially manageable threats to coral reefs including physical impacts from the use by snorkelers and divers. once coral reefs are damaged, they are less able to support the many creatures that inhabit them and also loses value as a tourist destination. yet by comparison to many other commercial uses of coral reefs, such as fisheries and mining, the direct impact of tourism is low, and therefore well planned tourism is likely to offer the most sustainable and profitable use of reef resources (jobbins, 2006; cesar et al., 2003). only recently tourism has become a popular mechanism to generate revenues and in this regard, user fees are the most popular instrument utilized. examples of user fee types include admission to parks, fees charged to divers, special fees for accommodations, trophy and hunting fees or even special fees for rescue services (hawkins, 1998). in the sri lankan context, out of the five existing categories of protected areas that falls under the purview of department of wildlife conservation (dwc), presently tourism is actively promoted as a source of revenue generator only within national parks (np). as stipulated in ffpo 1937 and its subsequent amendments, in a np the public can view and study wildlife by obtaining a permit paying a prescribed fee from an authorized person of the dwc. application of an entrance fee to enter into pinp took place only in may 2011. with the ending of the armed conflict in may 2009, the roads and access were opened to the eastern province leading a boom in the tourism industry in the region (dsd kuchchaveli, 2014; eml consultants, 2010; usaid, 2009). in the above context, the present study was undertaken with the objective of obtaining a better understanding of the opportunities available and answers to challenges encountered in the future coexistence of coral reef conservation and tourism at pinp, and to deliver a set of recommendations for better management of the coral reef and other biological resources of the area for the sustainability of the tourism industry associated with it. the methodology of the study was designed to find answers to following aspects: 1. visitor statistics and revenue generation through tourism 2. understanding the factors contributing to visitor satisfaction and dissatisfaction 3. present status of the coral reefs within pinp and whether the park management status is adequate to address the existing challenges 2. materials and methods information for the study was collected through field visits, formal and informal group discussions, expert opinions and literature surveys. semi-structured interviews were used to obtain key stakeholder (wildlife officials, hoteliers, boat and dive tour operators) perceptions and experience in coral reef management and conservation issues. the study was built upon the perera and kotagama /journal of tropical forestry and environment vol. 6. no 01 (2016) 20-35 23 information available on three recent reports produced under donor funded projects; greentech, 2009; and eml consultants, 2013 and 2010. the best available secondary literature on the mpa was gathered through web-based search as well as visiting the government and non-governmental institutions involved in coral reef conservation activities. in order to understand the perceptions of tourists with regard to their experience at pinp, online web–based information available at trip advisor was utilised. this is acceptable as the importance of the online social travel networks for tourism businesses is gaining new attention in the academic literature (xiang, 2010; ban and ramsaran-fowdar, 2013). the management effectiveness the pinp was calculated utilizing the score card method developed by the world bank-wwf alliance (staub and hatziolos, 2004). 3. results 3.1 visitor statistics and revenue generation preliminary study visit to pinp in october 2010 revealed that tourist were entering the national park without obtaining a permit to view wildlife, as stipulated by ffpo. when visitors were questioned on site as well as off-site, it was evident that they were not aware of the protected status of the park or that they were actually doing an activity which is prohibited by the law. the log book kept by the navy indicated that considerable number of people visited the island, especially during the holidays and weekends. for example, 2,045 individuals had visited the island in the month of september 2010. pinp was re-opened to the public and the issue of a permit was implemented by the dwc from 28 th may 2011. as illustrated by figure 2, within a 40 month period, a total of 146,375 tourists had visited the park and the largest visitor number was recorded in august 2014, with 14,368 individuals paying a visit to the tiny island. annually there are two peak visitor seasons, which seems to be coincide with school holidays and international tourist arrival to the country. in april, the park is mainly visited by locals, while in august both locals and foreigners visit the area. higher foreign tourist turnover is found in july-september period and the percentage of foreign tourist had increase from 11.9% in 2011 to 25.13% in 2014. with the onset of north-east monsoons in mid-october, the number of visitors drops considerably and therefore in december, tourist numbers are low. parallel to visitor numbers, the revenue generated by dwlc through the issue of permits had also increased and for the year 2013, the park earned lkr 17,510,460.00 (us $ 134, 695.85) being the np, that earned the highest revenue per ha of area protected (lkr. 37,000 ha -1 ). this is a considerable achievement compared to much larger category 1 parks † such as yala, and wilpattu (figure 3). for the year 2013 of the 18 nps that were open to visitors, pinp earned the number fifth and seventh positions in visitor preference and revenue generation. during that year nearly three percent of the revenue generated was from the pinp indicating that healthy coral reefs are preferred by tourist much as larger wild charismatic animals such as elephants and leopards. † as per the regulations under section 71 of ffpo (no. 1612/37, 31st july 2009), the entry fee paid by tourists to enter category 1 national parks are higher (local adult rs. 60 and foreign adult us$ 15 or equivalent to sri lankan rupees) than for category ii national parks (local adult rs. 40 and foreign adult us$ 10 or equivalent to sri lankan rupees) and pinp is considered as a category ii national park. charges specified for vehicles, services and vat are the same for the two categories 24 figure 2: visitor arrival at pinp from may 2011 to september 2014. (source: dwc). the issue of a permit to the tourists to observe wildlife within pinp (as per gazette extraordinary no. 1612/37, 31st july 2009) is complex and promotes “group tourism” rather than providing individual options. this permit includes different categories of monetary allocations and there is vast difference in the final payment of a local and a foreign visitor (table 1), indicating that a larger proportion of income generated is from foreign tourists. table 1: comparison of different financial allocations included with in a permit issued by the dwlc to local and foreign visitors at pinp (in sri lankan rupees). category of allocation local foreign park fees for entry (tourist) 40 1,280 local adult (boat driver) 40 service charges 300 1024 charges for parking the vehicle (boat) 125 125 12% vat 55.8 296.28 total for 1 individual 520.80 2,765.28 total for 8 individuals (including the boat driver for foreign tourists) 834.40 11,366.88 source: notice board of pinp ticketing office. as per legislation, this visitor permit can be issued to a party of person consisting of a maximum of 10 persons (including the driver) and in the case of pinp this number is reduced to eight as it is the maximum carrying capacity of most boats entering the park. this fee system is perera and kotagama /journal of tropical forestry and environment vol. 6. no 01 (2016) 20-35 25 displayed at the ticketing counters and personal observations indicate that it confused especially the foreign tourists. discussions with officials at dwc headquarters revealed that a new gazette is about to be issued simplifying the present payment system and that individual tickets will be available thereafter. figure 3: comparison of visitor numbers, revenue earned and income/ha in national parks for the year 2013. 3.2 boat operators and their concerns presently 50 boats bring in tourists to the pinp, and out of this 33 belongs to the nilaveli tourist boat and service co-operative society ltd (ntbscs), which is registered in the provincial economic ministry since april 2014. six boats are operated by the hotels located within the nilaveli beach stretch including nilaveli beach hotel, sea view, pigeon island beach resort, pigeon island view and the jungle beach. other boats are operated by the dive centers (e.g. poseidon, aqua diving center etc.), and about five boats are entering the park from other parts of trincomalee (e.g. boats belonging to hotel chaaya blue, which is located about 10 km away from the pinp). other than that sri lanka navy utilises boats to bring in their staff members to the island, who are stationed there for security purposes. 26 the boats of the ntbscs are operated from two points within the nilaveli beach, which is presently not a continuous beach stretch due to the installation of a navy radar system. 15 boats are operated near to nilaveli beach hotel, while 18 enter the park from gopalapuram. when considering the ethnic composition of the boat operators of these two locations, there is a considerable variation to be seen, with in gopalapuram the majority being tamils, while at nilaveli beach point the majority are muslims (figure 4). an ethnicity difference was a barrier that was overcome when forming ntbscs, which took few years’ continuous deliberations. figure 4: ethnic composition of the boat operators of ntbscs. of the 33 ntbscs boats, nine are driven by the owners, while the rest is operated by hired drivers (mainly fisherman from the area) for a daily payment (lkr. 500 for one trip and lkr 800 for two trips). from april 2014, the society charge lkr 2,000 from tourists for a trip to pinp and the boat can accommodate a maximum of seven tourists. although the distance to the park slightly differs from the two boat launching points, the charge is the same. ntbscs is still not issuing a receipt for the boat service and the amount charged is too not displayed. if possible they try to overcharge the visitors. as illustrated in figure 5, the monthly revenue earned by the operators fluctuates and they face financial hardships, from november to march with limited turns to operate due to rough sea conditions. for example, in january 2014, for 14 days no boats were operated, while for the whole month only 120 boat terns were reported. the highest financial gains are from august. for example in 2013, 2,542 boat terns were reported, and if assuming that 40 boats were in operation during that month, they earn more than lkr. 127,100 per boat during that period. these operators also rent snorkeling gears to tourists, charging lkr 300-600 per set. additionally they also offer whale watching and deep sea fishing tours and thereby diversify their livelihoods. lack of parking space at pinp is also an issue faced by the boat operators as well as the visitors. presently there is space to park 15 boats and during the peak season these slots are mainly occupied by boats belonging to hotels and diving centers, who bring in divers and snorkelers that spend more than two hours in the park. therefore, the ntbscs operators have to anchor outside perera and kotagama /journal of tropical forestry and environment vol. 6. no 01 (2016) 20-35 27 the park limits or go back to the point of origin. they have turn this opportunity brings more tourists during the peak periods and this some time lead to arguments between the visitors and boat operators. figure 5: boat turns and no of days without boats entering pinp. source: dwc. 3.3 dive tour establishments another stakeholder who directly depends on pinp is the dive tour establishments. the diving season in nilaveli starts in april and ends in september or mid-october. there are eight diving centers within the vicinity of pinp. this diving center not only offers diving expeditions, but also the opportunity to obtain padi diving license. as per the information gathered from discussion with dive tour operators, around the sea coast of trincomalee there are around 12 diving sites. the park is not a preferred diving site due to two reasons; entrance fee and the shallowness of the area. yet the park is used for training padi divers as well as for snorkeling and many dive centers utilized sea areas just adjoining the park boundary for diving. 3.4 visitor perceptions the visitor reviews (n=150) downloaded from trip advisor (11 th october 2014) were from tourist that have visited the pinp from july 2012 to october 2014, with majority visiting the island in 2014. the contributors belong to 34 countries, with 50% being from europe (figure 6 a and b). the reviews indicates that the main objective of visiting pinp is for snorkeling, while personal observations indicated that bathing is preferred by most local tourists. the overall visitor experience for pinp was “very good” with 76% indicating that their experience was either excellent (46%) or very good (30%). abundance of marine life and swimming with harmless reef sharks were sighted as reasons for the positive experience (figure 7 and table 2). 28 figure 6: analysis of trip advisor reviews by the (a) year and (b) country. table 2: five most positive and negative visitor comments and suggestions to overcome the negative issues. positive comments % negative comments % suggestions abundance of colourful marine life 69.1 overcrowded 27.0 go before 10.30 a.m., limit the daily visitor numbers swimming with harmless reef sharks 56.6 reef damage 22.4 awareness, guides to direct the visitors; zonation; construct a platform to reach deeper areas; not letting the locals use the area as bathing site easy access to reefs 15.8 high price 21.1 go as a group variety/good coral cover 14.5 lack of visitor facilities (water, food, changing rooms, toilets, and shelter) 19.8 bring your own food and water; come attired for swimming; apply sun screen encounter with turtles 13.2 lack/poor management 15.8 re-think the park strategy; park guards to be more proactive; utilize the revenue generated for conservation purposes these ratings when compared to hnp (where only 9% had an excellent trip, while 33% had a poor or terrible experience) is good, yet when comparing with terrestrial nps such as minneriya , udawalawe and horton plains where less than 5% of the visitors had poor or a terrible visitor experience, is not so encouraging. as indicated in table 2 the main reason for poor visitor experience at pinp was overcrowding, which directly affect reef health. only very few tourists venture inside the island to observe other attractions such as geological features or the nationally threatened wild rock pigeons. perera and kotagama /journal of tropical forestry and environment vol. 6. no 01 (2016) 20-35 29 figure 7: visitor experience in six national parks of sri lanka. source: http://www.tripadvisor.com (accessed on 11 th october 2014). 3.5 present status of the coral reef continuous in-depth scientific studies on the coral reefs ecosystem of pinp are lacking, and this is mainly due to inability to access the area during the civil conflicts that lasted for 30 years. most of the information available is based on ad hoc surveys undertaken under various short-termed projects and initiatives. a research conducted in 1999 concluded that the live coral cover was 40% (rajasuriya and karunaratne, 2000). the live coral cover at pinp has reached its peak in 2005 (74 %) as indicated in rajasuriya, 2005, yet a study undertaken in 2013 reveals that only 21% of live coral cover is available (eml consultants, 2013). this reduction can be attributed to increased threats and disparities in methodology utilised (especially the placement of transect including the location and the depth range) for each study. as per expert opinion, threats such as visitor pressure, cots infestation, accelerating growth of halimeda sp., solid waste and coral bleaching are presently affecting the health of the coral reefs at pinp (table 3). further in 2010 there was severe bleaching of the coral reefs in the area, and they are now somewhat recovered (rajasuriya, 2012). pressures from destructive fishing including dynamiting, although reduced within the park limits are still practices in the vicinity and thereby influence the biological diversity, with serious impact on populations of mobile and mid-sized schooling species like snappers, sweetlips, trevally etc. setting of fish traps in shallow reef areas is another threat recorded. although pinp is strictly a “no take zone”, under the provision of the ffpo, yet prohibited fishing activities are still reported sporadically. as per information obtained by dwlc office at pinp reveals that during the last three year period (january 2012 – september 2014) dwlc had filed six cases against 10 fishermen who were involved in illegal fishery activities within the park boundaries. the offenders are prosecuted under two offences; entering the park without a permit http://www.tripadvisor.com/ 30 and remaining and catching fish. in a case that was concluded in 2014 the offenders were fined lkr 15,000 per individual for the first offence and lkr 20,000 for the second. it is encouraging to note that the fishery permit issued under the fisheries and aquatic resources act (fara) by the fishery inspector of trincomalee north clearly stipulates that fishing is prohibited with in pinp limits. this stipulation has made it easy to prosecute the offenders. recently a case was filed by a concerned tourist with regard to breaking of live coral corals within the np and the verdict in this regard is still pending. this case highlights the fact that awareness in law amongst the general public can assist the concerned authorities to protect the natural resource base. table 3: expert opinion on reasons for coral reef degradation at pinp. threat ranking of threat * reasons for damage / general comments 10 years ago present condition threats related to visitor pressure 5 3 collection of coral as souvenirs had reduced, yet visitor pressure had increased with incidents of reef trampling and boat damage to corals this pressure is localized. crown of thorn starfish infestations 4 3 increase of cots has been reported, which could change with season. ad hoc removal takes place. destructive fishing activities including blast fishing 2 3 applies to fish populations in the adjacent areas, to np. but serious impact on fish populations and to tourism in the longer run accelerating growth of calcareous algae (halimeda sp.) 4 3 the bleaching event in may 2010 have led to a phase shift occurred where other species benefitted, which included calcareous algae. invasion by corallimorpharians 3 4 corallimorpharians invaded parts of the reef in 19992000 period. the areas carpeted by this species have not increased significantly cyclones not aware of damage by cyclones tsunami 4 low damage to pinp medium damage to coral island. coral bleaching 5 3 severe bleaching in 2010, but all corals did not die and recovery is taking place. sedimentation 5 5 there is not much sediment here solid waste 5 4 the degree of wastes from visitors has decreased due to awareness, yet marine debris that drift with the current get accumulated on the island edges. coral diseases 4 4 ? nutrient inputs ? 4 sewage pollution along the shoreline water in nilaveli * percentage is based on the extent of damage compared to the whole area. recovery is estimated from the time the threat is removed. very high (1): extensive damage (80%–90%) to almost the entire habitat and will take at least 10 years to recover; high (2): significant damage (50%–79%) and damaged areas can recover within 7 years; medium (3): damage (20%-49%) is readily visible and damaged areas can recover in 4 years; low (4): damage (10%-19%) is very localized but readily visible, and recovery is within 2 years; very low (5): damage is <9% and very localized and visible only by searching for damaged areas. perera and kotagama /journal of tropical forestry and environment vol. 6. no 01 (2016) 20-35 31 accelerated ad hoc development is also posing a threat to the survival of pinp. nilaveli beach front is earmarked for tourism development. as indicated previously part of the buffer zone of pinp falls within the nilaveli beach and stipulated by ffpo no development is permitted with in this area. as this situation is not helpful for the hotel industry development, the option of degazetting of pinp was considered in 2013. due to pressure from environmental groups, it did not materialize, yet now the policy makers are looking at the option of shifting the boundaries of the park to facilitate tourism development. 3.6 present park management status at present, the enforcement at pinp by its management authority (the dwc) is not up to desirable levels as indicated in visitor perceptions and by the value received for management effectives through the score card approach (42.98% as indicated in table 4). lack of a management plan as well as staff that are well trained in managing mpas are hindering dwc’s ground level management efforts. dwc manage two ticketing/permit issue points within the nliaveli beach stretch (i.e. the same locations where the boat operates: near to nilaveli beach hotel and gopalapuram) and also maintain two other small offices: one in the nilaveli beach and the other in the village. presently there are only eight staff member including four volunteers (who are daily paid). as ticketing is done manually, at least four staff members are required in the two ticketing offices, especially during peak tourist season and as a result the number of staff on the island itself to manage the visitors are limited to one or two. frequent transfer of staff is also a problem. a motorboat has been recently acquired through a gef funded small grant project, while navy and police assist in monitoring visitors. table 4: management effectiveness of pinp score card summary (as of october 2014). maximum possible score your score final score (%) acontext where are we now bplanning -where do we want to be cinputs -what do we need dprocess how do we go about management eoutputs –what were the results foutcomeswhat did we achieve 26 14 14 25 33 27 14.5 04 07 8.5 15.75 10 55.76 28.57 35.71 50 34.0 47.7 total score 139 59.75 42.98 it is well known fact that at entrance points park managers have the most control over visitor numbers, distribution and behavior. ideally as in other popular terrestrial nps, when visitors arrive, they proceed immediately through a reception area where they can be met, have regulations explained, numbers counted, entrance fees collected and tours arranged with a tracker. yet, as this is not practical at pinp, a visitor center that will ensure visitors have information about where to go, what to do and what not to do during the visit is required on land. 32 4. discussion tourism, like other economic development tools, is a two-edged sword, with the economic, learning and political benefits of tourism come potentially significant social and environmental costs, and these costs may be particularly deleterious in and near protected areas. with careful sensitive management attending to the notion of sustainability, these costs can be minimized (mccool, 2006). as tourism demand at pinp is increasing, there is the need to move towards greater industry selfregulation, training and accreditation to ensure more efficient management of tourism use at the park as well its surroundings. if managed in isolation, coastal and marine protected areas are vulnerable to natural resource development and exploitation occurring outside these areas and therefore it is recommended widely that mpas should be integrated into spatial development strategies for larger areas, under the umbrella of integrated coastal and ocean management (icm). a good example in this regard is found from belize barrier reef, the current 14 mpas are treated as tools for achieving icm (cicin‐sain and belfiore, 2005). with respect pinp, participating in special management area (sam) process of the coast conservation department (ccd) is vital in this regard. the 2006 coastal zone management plan prepared by ccd identifies the nilaveli beach and the pigeon island as a potential sam site. amendments to the coast conservation act, no. 57 of 1981, in february 2011, provides legal provision to declare sam sites through gazette notifications if it need to adopt a collaborative approach to planning resource management within the defined geographic area. further the minister in charge of ccd may make regulations prescribing the manner and mode in which, and the persons by whom, such sam site should be administered, the persons entitled to have access to these areas and the activities which can be carried out within such areas. gef funded participatory coastal zone restoration and sustainable management in the eastern province of post-tsunami sri lanka, which is being presently implemented by the ministry of fisheries and the coast conservation department, promotes the restoration and sustainable use of ecosystems along the eastern coast of sri lanka damaged by the indian ocean tsunami through the sam approach. this project will strengthen the capacity of dwc to manage pigeon island national park and enforce park rules. dwc will be supported in developing a management plan for pigeon island and its vicinity that meshes with the community co-management plan with the aim of establishing a sanctuary to demarcate a strict conservation area for the core reef with limited resource extraction beyond. coordination between the national park management plan and the community co-management plan will be essential to ensure no conflicts arise. the capacity to apply different types of fee system from different park users has not been explored at the pinp. this is not the case in elsewhere of the world. for example a survey conducted in caribbean and central america indicate that out of 74 mpas throughout the region, 53 mpas (70%) use different types of fee system with charges being levied per dive, per day, per boat, and per tank. in some cases charges are not levied on individual divers but on operators as an annual fee or percentage of income. thirty-four (64%) of the mpas charging scuba divers levy a fee on individual divers. this ranges between usd 1 and usd 50 although fees at the lower end of this scale are most usual (green and donnelly, 2003). further studies conducted in three major dive destinations in philippines indicate that most divers would be willing to pay an entrance fee to maintain sanctuaries where fishing one of the perera and kotagama /journal of tropical forestry and environment vol. 6. no 01 (2016) 20-35 33 major threats to coral reefs is prohibited. moreover, the entrance fee may be used as a tool to regulate the number of visitors to minimize visitor damage. these revenues could be used to support coral reef conservation and possibly the creation of alternative employment opportunities for locals who would be barred from fishing, their traditional income generating activity (arin and karmer, 2002). however, at pinp, very limited portion of the revenue generated is used for conservation purposes at the site itself, while the larger portion of the money earned from permits is either sent to the treasury of the central government and to the dwc headquarters. 4. conclusion and recommendations the proposition that pinp management should lead to win-win outcomes for both conservation and tourism development satisfying the needs of all relevant stakeholders including conservationists, government officials, tourists, and tourism operators was the dominant paradigm addressed in this case study. the successful achievement of this dual mandate is more complex than in theory and therefore the park management options needed to be re-thought off. it is evident that the growth of tourism in the east coast has resulted in an increasing number of tourists visiting pinp, despise the impose of an entrance fee system. analysis of data indicated that one hectare of healthy coral reef can earn more revenue than from a larger terrestrial parks that provide a home to charismatic species such as elephants and leopards with bigger home ranges. the examining visitor perceptions indicated that swimming with a multitude of colourful fish, and the black tip reef shark is the main attraction for snorkelers. it also reveals that the reef is being degraded at pinp and the park is over-crowded especially in april and again in august– september period, leading to visitor dissatisfaction as well as reef degradation. this indicates that although user fees can be useful for raising much-needed revenue, there are several dangers in this funding mechanism. one is the risk of over-commercialisation promoting mass tourism. a pa which emphasizes user-fee revenues can lose sight of its primary conservation objectives and overdevelop facilities designed to produce income rather than protect natural resources. other risks include deploying scarce resources toward collecting fees rather than protecting resources, creating controversy and public opposition, a fact that is evident from the visitor reviews, where poor/nonpark management interventions as well as lack of visitor services have been highlighted. further the degradation of reef ecosystem due to a. planci attacks as well as a continuous monitoring programme to check the health of the reef need to be addressed in a more systematic manner, with the involvement of stakeholders including universities, dive tour operators as well as boat operators. given the seasonal nature of tourism industry incomes that mainly depend on weather patterns, the boat operators find it difficult to secure a dependable livelihood throughout the year. providing them with alternative sources of income as well as proper guidance in conducting tourism will assist in both. park management must pay close attention to tourism impacts in the future. failure to do this could result in a destructive feedback loop that would contribute to the degradation of the reef and, ultimately, pinp’s diminished competitiveness in the tourism industry as a destination for viewing a healthy coral reef. as stated by one tourist “the national parks department really need to rethink their strategy here, otherwise there will be nothing left in five years and you can wave goodbye to the sharks and turtles”. 34 following recommendations are provided for meeting the challenges for promoting both reef conservation and sustainable tourism at pinp.  the boundary of pinp could be re-demarcated in a manner that will not have an impact on tourism developments in the nilaveli beach, but it should captures more marine areas so that illegal activities such as blast fishing can be better managed.  dwc to actively involve all relevant stakeholders in all stages of pa management planning, development and implementation. i.e. in reef monitoring removal of cots, patrolling, financial resources.  in depth studies are needed to be undertaken for better understanding on the importance of maintaining a healthy reef at pinp. such studies include spillover effect, visitor carrying capacity, economic analysis (willingness to pay extra for preserving the reef and limiting the tourist numbers).  introducing concept such as “green-fin operators” to protect and conserve coral reefs by establishing and implementing environmental friendly guidelines for divers need to be looked into.  the nilaveli tourist boat and service co-operative society ltd (ntbscs) need to be empowered with a professional outlook in handling visitors as well as managing the society. due to seasonality of the industry, alternative livelihoods need to be introduced.  maintaining two ticketing issue offices by dwc is not practical in the long run and one central office complex together with visitor interpretation facilities needed to be established.  implementation of a variety of user fee structures can be applied to enhance the economic rerun from the park and thereby making it more attractive to government for keeping it protected.  to channel tourist demand from the fragile coral reef ecosystem to more impact-resilient areas such as a theme park can be built in the surrounding beach front.  pinp could be included within a much wider management system such as a special area management site. acknowledgment the authors thank the department of wildlife conservation and especially its officials based at pigeon island national park. mr. arjan rajasuriya and nishan perera is acknowledged for providing feedback on coral reef status. references arin, t., and kramer, r., 2002. divers’ willingness to pay to visit marine sanctuaries: an exploratory study. ocean & coastal management 45:171–183. ban, j., and ramsaran-fowdar, r.r., 2013. developing a model for online social travel networks in the tourism industry. proceedings of 23rd international business research conference 18-20 november, 2013, marriott hotel, melbourne, australia, isbn: 978-1-922069-36-8. cicin-sain, b., and belfiore, s., 2005. linking marine protected areas to integrated coastal and ocean management: a review of theory and practice. ocean & coastal management 48(1112): 847-868. cesar, h., burke, l., and pet-soede, l., 2003. the economics of worldwide coral reef degradation. cesar environmental economic consulting, amsterdam. perera and kotagama /journal of tropical forestry and environment vol. 6. no 01 (2016) 20-35 35 de bruin, g., 1972. the crown of thorn starfish acanthaster planci (linne) in ceylon. bull. fish, res. stin., sri lanka, 23(1 & 2): 37-41. dsd kuchchaveli., 2014: divisional resource profile of kuchchaveli division, 2014. eml consultants (pvt) ltd., 2013. consultancy services for establishing baseline inventories of flora and fauna in three identified coastal ecosystem in the eastern province part i – pigeon island national park and surrounding coastal ecosystems. eml consultants (pvt) ltd., 2010. an analysis of current and future economic value of coastal resources in the eastern province in sri lanka. study 14. north east coastal community development project. green, e., and donnelly, r., 2003. recreational scuba diving in caribbean marine protected areas: do the users pay? ambio 32(2). royal swedish academy of sciences 2003. 140-144. greentech consultants., 2009. a review of coral reefs on the east coast of sri lanka: distribution, ecology, status and threats, final report, pp 93, annexure 04, august 2010, nec/po/tecs(iii)/08/18,neccdep/greentech consultants, adb loan 2027 sri (sf): north east coastal community development project (neccdep). iucn sri lanka and the central environmental authority. 2006. national wetland directory of sri lanka, colombo, sri lanka. 229-233. iucn sri lanka., 2002 conservation of coral reefs around pigeon island, trincomalee, issue paper, prepared by iucn sri lanka with technical inputs from nara. jobbins, g., 2006. tourism and coral reef conservation: can they co-exist? in isabelle m.c. and john, d.r. (eds) coral reef conservation. conservation biology cambridge university press. 13: 237-262. mccool, s., 2006. managing for visitor experiences in protected areas: promising opportunities and fundamental challenges parks. the international journal for protected area managers. the visitor experience challenges. 16(2): 3-9. rajasuriya, a., 2012. provisional checklist of corals in sri lanka. in weerakoon, d.k. and wijesundara, s. (eds) the national red list 2012 of sri lanka; conservation status of the fauna and flora. ministry of environment, colombo, sri lanka. 376-383. rajasuriya, a., perera n., fernando m., 2005. status of coral reefs in trincomalee, sri lanka. in souter, d. and lindėn, o. (eds). coral reef degradation in the indian ocean: status report 2005. cordio, department of biology and environmental science, university of kalmar, sweden. 97-103. rajasuriya, a., 2005. the status of coral reefs in sri lanka in the aftermath of the 1998 coral bleaching event and the december 2004 tsunami. in souter, d. and lindėn, o. (eds). coral reef degradation in the indian ocean: status report 2005. 83-96. rajasuriya, a., and karunaratne, c., 2000. post-bleaching status of the coral reefs of sri lanka. coral reef degradation in the indian ocean: status report and project presentations 2000. 5463. staub, f., and hatziolos, m., 2004. score card to assess progress in achieving management effectiveness goals for marine protected areas. prepared for the world bank. revised version july 2004. usaid, 2009. assessment of tourism in eastern, uva and north central provinces of sri lanka. prepared under usaid contract number 383-c-00-08-00500-00. sri lanka connecting regional economies (usaid/core) programme. xiang, z., and gretzel, u., 2010. role of social media in online travel information search. tourism management, 31:179-188. chapter five: discussion izekor & erakhrumen /journal of tropical forestry and environment vol. 5. no 01 (2015) 31-40 31 physico-mechanical properties of cement-bonded particle boards of bambusa vulgaris and gmelina arborea fibres d.n. izekor * and a.a. erakhrumen department of forest resources and wildlife management, faculty of agriculture, university of benin, benin city, nigeria date received: 03-01-2015 date accepted: 25-05-2015 abstract this study investigated the effect of pre-treatment and particle geometry/stratification on the physical and mechanical properties of cement-bonded particle boards (cbpbs). 6 mm thick homogeneous cement-bonded particle boards were made from gmelina arborea roxb. sawdust and bambusa vulgaris shard. fibres with type 1 portland cement. the cbpbs were manufactured at four particle geometry/stratification levels and three pre-treatment levels. the cbpb was manufactured with a cement wood ratio of 3:1, board density of 1500 kg/m 3 , board size of 350×350×6 mm and a pressing pressure of 1.23 n/mm 2 . the cbpbs were tested for modulus of rupture (mor), modulus of elasticity (moe), thickness swelling (ts) and water absorption (wa). the mor obtained for each of the 12 factor combinations in this experiment ranged from 2.02 to 11.27 n/mm 2 while moe value ranged from 253.88 to 4942.60 n/mm 2 . the mean percentage for water absorption (wa) values ranged from 8.78% to 35.66% while mean ts values ranged from 0.16% to 15.71%. stronger and stiffer boards were produced using the sawdust/fibre/sawdust geometry stratification. calcium chloride pre-treatment increased the mechanical properties of the boards, while al2(so4)3 improved their physical properties. there were significant differences between particle geometry and pre-treatment on both physical and mechanical properties of cement-bonded particle board (p<0.05). keywords: fibre stratification, modulus of rupture, modulus of elasticity, thickness swelling, water absorption 1. introduction fibre reinforcement of concrete remains an exciting and innovative technology because of its unique engineering properties. presently, the major raw materials for cement-bonded particle boards consist mainly of wood, cement and water with or without a catalyst (ajayi, 2005; papadopoulos, 2008; ajayi, 2011). the acceptability of these products stems from their availability and widespread distribution of local raw materials. the scarcity of the economically preferred wood species and overexploitation of natural and plantation hardwood species coupled with lack of effective utilisation of wood resources due to huge wastes by wood processing industries call for concerted efforts by researchers and wood scientists to initiate common solutions to the rapid depletion of wood resources in nigeria. finding alternative sources of raw materials for wood industries to manufacture panel * correspondence: david.izekor@uniben.edu tel: +234 08039280692 issn 2235-9370 print/issn 2235-9362 online © university of sri jayewardenepura 32 products would meet the ever increasing demand of wood products for construction works in nigeria and the world in general. the extraordinary mechanical performances of bamboo originate mainly from its fibre components (amada and untao, 2001). bamboo fibres are much stronger and stiffer than most wood fibres, indicating that more attention should be focused on the utilisation of bamboo fibres in the production of high performance fibre reinforced composites (yu et al., 2011a; 2011b). bamboo and wood fibre composite are exceptional, not only because of their eco-friendly nature, but also because they provide an economic and socially useful outlet for bamboo chips, wood residues and agricultural wastes. the combination of bamboo and wood particles with the inorganic cement binder in the production of a cement bonded particle board (cbpb) can produce a new class of building products that will reflect the good characteristics of wood, non-wood and concrete. particle geometry influences virtually all properties of cement-bonded particle board (frybort et al., 2008). wood composite properties can be engineered to an extent, by adjusting the particle geometry and their arrangement. this implies that particle geometry affects the strength and physical properties of the composite and as such the mixture of different fibre particles and particle geometry in a layered arrangement of a multi-layered cement-bonded particle board (cbpb) should have a significant effect on the strength and physical properties of the product. the objective of this study is to determine the effects of different particle stratification and geometry on the physical and mechanical properties of cement-bonded plastic composites. the influences of particle layering and different pretreatment on the properties of the composites were also evaluated. 2. methodology the study was carried out at the forest product development and utilisation department of forestry research institute of nigeria (frin), located at jericho in ibadan, the capital of oyo state, nigeria. 2.1 fibre acquisition two components were involved in fibre acquisition. these were the non-wood component and the wood component. for the non-wood (bamboo fibre) component, fresh culms of bambusa vulgaris were harvested and the nodes on the culms were removed and prepared into chips. the processed chips were then processed for fibre analysis. the second component involved the collection of gmelina arborea sawdust from the sawmill section of the forestry research institute of nigeria. the sawdust was air-dried to a constant moisture content of 12% in a controlled laboratory and then processed for fibre/particle analysis. 2.2 fibre analysis bambusa vulgaris maceration was done by soaking the chips in water for 48 hours and then gently beaten to release the fibres (wise et al., 1946; gills and onuga, 1989). the fibre dimensions were thereafter measured and recorded. gmelina arborea the dried sawdust was thoroughly sieved using 2.0 mm and 1.0 mm sieves while the geometry was obtained by passing the sawdust through the sieves. izekor & erakhrumen /journal of tropical forestry and environment vol. 5. no 01 (2015) 31-40 33 2.3 pre-treatment and treatment additives both bamboo fibre and gmelina wood sawdust were pre-treated with hot water in an aluminium hot bath at 100 0 c for a period of one hour. thereafter, the water was drained off and the particles were dried to a moisture content of 12%. three treatment regimens were carried out for the four board types. the first was the control regime with no treatment followed by the calcium chloride (cacl2) additive and the aluminium sulphate (al2(so3)4) additive. for each mineralising chemical additives, 2% weight of cement was added to the cement-wood slurry. 2.4 sample preparation six sample boards were produced for each particle geometry type and treated according to the cement-wood mixing ratio 3:1. from these sample boards, two test samples were cut out for physical and mechanical properties tests, using prescribed dimensions. a total of 12 test samples were used for each fibre geometry type. the wood particles and the cement for the board manufacture were weighed, recorded and labelled for identification. the required quantity of wood particles and cement was weighed and placed in a plastic container. the solution of 2% calcium chloride and water was added in a uniform proportion and blended together to form slurry. this same procedure was done for other treatment regimens. wooden moulds of known dimensions were placed on a wooden plate and covered with a polythene sheet to prevent sticking of the formed boards onto the plate. the slurry was now spread out on the plate in the wood mould, after which, a wood press was used to pre-press the furnish within the mould to enhance uniform mat formation and to reduce the thickness of the formed mat. the mat formed was properly labelled using a paper cello tape to distinguish between boards from different particle geometry and different treatment regimens. the labelled mat was covered with polythene sheet, thereafter a top metal plate was placed on it and transferred to the cold press under a pressing pressure to a specified thickness for a period of 24 hours before demoulding. cold pressing was done using a hydraulic cold press machine. after pressing, the demoulded boards were stored inside sealed polythene bags for 28 days to enhance curing of the cement binder. the cured boards were trimmed to avoid edge effect and cut into test specimen sizes for testing. the boards were tested for modulus of rupture (mor), modulus of elasticity (moe), water absorption (wa) and thickness swelling (ts). 2.5 testing for physical properties test samples measuring 50×50 mm were used for physical properties determination according to british standard 373 (1989). the properties tested were water absorption and thickness swelling. measurements of thickness (mm) and weight of the samples were taken prior to test as initial parameters while the final measurement was taken after immersion in distilled water for 24 hrs. digital calliper and electronic weighing balance was used to measure thickness swelling and weight of the test samples. the different parameters were calculated using the equation. water absorption   100 w1 w1 w2%wa        (1) where: wa= water absorption (%) w2 = final weight after treatment (g) w1 = initial weight before treatment (g) 34 thickness swelling   100 t1 t1 t2%ts        (2) where: ts (%) = thickness swelling in percentage t2 = final thickness after treatment (mm) t1 = initial thickness before treatment (mm) mechanical properties the modulus of rupture test was carried out using test samples measuring 50×150 mm on a hounsfield tensiometer machine according to british standard 373 (1989). the test samples were supported by two rollers at both ends and loaded at the middle of the span until failure occurs. mor was calculated from the maximum load at which each sample failed. modulus of elasticity (moe) was calculated using the load to deflection curve plotted on the graph by the hounsfield tensiometer testing machine as expressed in the equation below: 2 2bd 3pl mor  where: mor = modulus of rupture (nmm -2 ) p = the ultimate failure load (n) l = the wood sample span between the machine support (mm) b = width of the wood sample (mm) d = thickness of the wood sample (mm) δs4bd δpl moe 3 3  (4) where: moe = modulus of elasticity (nmm -2 ) p = increment in load (n) l = the span of the sample between the machine support (mm) b = width of the sample (mm) d = thickness of the sample (mm) ∆s = increment in deflection corresponding to increment in load. analysis of variance was carried at 0.05% probability level to estimate the level of significance among the various parameters tested while separation of means was carried out using duncan multiple range test. 3. results and discussion 3.1 physical properties water absorption the results of the mean values of cement-bonded particle boards (cbpbs) after 24 hours of water absorption (wa) with cacl2 treatment after 24 hours are presented in figures 1 and 2. the values were 11.75, 8.78, 25.89 and 12.08% for sawdust-fibre-sawdust (s-f-s), fibre-sawdust-fibre (fs-f), sawdust only (s only), and fibre only (f only) particle geometry/stratification levels respectively. (3) izekor & erakhrumen /journal of tropical forestry and environment vol. 5. no 01 (2015) 31-40 35 the mean values of cbpbs for water absorption treated with al2(so4)3 were 11.84, 13.27, 12.00 and 13.93% for s-f-s, f-s-f, s only and f only particle geometry/stratification levels respectively while the mean values for cbpbs produced with no chemical treatment were 14.60, 27.44, 35.66 and 24.94 for s-f-s, f-s-f, s only and f only particle geometry/stratification levels respectively (figures 1 and 2). cement-bonded boards produced with additive chemical of al2(so4)3 had a lower rate of water absorption compared to those produced with additive chemical of cacl2 while cement-bonded board produced with no chemical treatment had the highest rate of water absorption. the high rate of water absorption observed in cbpbs treated with cacl2 could be attributed to the hygroscopic nature of the chemical. this observation is similar to earlier report by xu and stark (2005). the authors reported that within each treatment, it was observed that boards produced with the s-f-s (sawdust/fibre/sawdust) matrix stratification were the most resistant to water absorption. thickness swelling the results of thickness swelling percentage of cement-bonded particle boards are presented in figures 1 and 2. the mean thickness swelling percentage of cbpbs treated with cacl2 after 24 hours of water absorption were 2.66, 3.39, 0.95 and 1.13% for sawdust-fibre-sawdust (s-f-s), fibre-sawdustfibre (f-s-f), sawdust only (s only), fibre only (f only) particle geometry/stratification levels respectively. the mean thickness swelling percentage of cbpbs treated with al2(so4)3 after 24 hours of water absorption were 0.83, 1.37, 0.16 and 0.33% for s-f-s, f-s-f, s only and f only particle geometry/stratification levels respectively while the mean thickness swelling percentage for cbpbs produced with no chemical treatments were 1.44, 15.71, 2.30 and 5.58% for s-f-s, f-s-f, s only and f only particle geometry/stratification levels respectively. cement-bonded boards produced with the al2(so4)3 treatment additives exhibited the least change in thickness swelling (figure1). this was followed by boards produced with the cacl2 and no treatment additive respectively. within each treatment as shown in figure 3, boards produced with sawdust only exhibited the least mean thickness swelling values. this shows that boards produced with sawdust only were the most dimensionally stable in terms of thickness swelling, followed by boards produced with fibres only. the observation made on the mean thickness swelling of the treated boards ranged from 0.16% to 3.39% compared to the thickness swelling values of cbpbs with no chemical treatment which ranged from 1.44% to 15.71%. this shows the effect of chemical treatment on thickness swelling. the thickness swelling percentages observed in this study compared favourably with ranges of 1.56% to 3.95% as previously reported by morteza et al. (2011) on the influence of wood extractive and additives on the hydration kinetics of cement paste. 0 5 10 15 20 25 30 cacl2 al2(so4)3 no treatment cacl2 al2(so4)3 no treatment water absorption thickness swelling p e r c e n ta g e ( % ) figure 1: effect of pre-treatment on water absorption and thickness swelling of cbpbs. 36 figure 2: effect of chemical treatments and fibre geometry on water absorption of cement-bonded particle boards. figure 3: effect of chemical treatments and fibre geometry/stratification on thickness swelling of cement-bonded particle boards. 3.2 mechanical properties modulus of rupture the results of the mechanical properties of cement-bonded particle boards are presented in figure 4. the mean values of mor for cbpbs treated with cacl2 were 11.27, 7.34, 6.34 and 10.20 nmm -2 for sawdust-fibre-sawdust (s-f-s), fibre-sawdust-fibre (f-s-f), sawdust only (s only), fibre only (f only) particle geometry/stratification levels respectively. the mean values obtained for mor for cbpbs treated with al2(so4)3 were 6.27, 3.43, 3.86 and 3.20 nmm -2 for s-f-s, f-s-f, s only and f only particle geometry/stratification levels respectively while the mean values obtained for cbpbs produced with no chemical pre-treatment were 3.35, 4.72, 5.21 and 2.02 nmm -2 for s-f-s, f-s-f, s only and f only particle geometry/stratification levels respectively. the effects of chemical pretreatment on the modulus of rupture of cement-bonded particle boards are presented in figure 5. it was observed that cacl2 treated boards has the highest mor values, followed by boards treated with al2(so4)3. cbpbs produced with no chemical pre-treatment have the lowest mor values. also cbpbs produced using different particle geometry had greater mor values in the sawdust/fibre/sawdust stratification followed by fibre/sawdust/fibre stratification. 0 5 10 15 20 25 30 35 40 s-f-s f-s-f s only f only s-f-s f-s-f s only f only s-f-s f-s-f s only f only cacl2 al2(so4)3 control w a ( % ) production factors 0 2 4 6 8 10 12 14 16 18 s-f-s f-s-f s only f only s-f-s f-s-f s only f only s-f-s f-s-f s only f only cacl2 al2(so4)3 control t h ic k n e ss s w e ll in g ( m m ) production factors izekor & erakhrumen /journal of tropical forestry and environment vol. 5. no 01 (2015) 31-40 37 3.2.2 modulus of elasticity the mean values of moe obtained for cbpbs treated with cacl2 pre-treatment were 3796.10, 3575.90, 2835.80 and 4942.60 nmm -2 for sawdust-fibre-sawdust (s-f-s), fibre-sawdust-fibre (f-s-f), sawdust only (s only), fibre only (f only) particle geometry/stratification levels respectively. the mean moe values obtained for boards with al2(so4)3 pre-treatment were 1747.20, 745.52, 842.82 and 1472.60 nmm -2 for s-f-s, f-s-f, s only and f only particle geometry/stratification levels respectively. the mean moe values obtained for cbpbs with no pre-treatment were 629.44, 1110.20, 1686.30 and 253.88 nmm -2 for s-f-s, f-s-f, s only and f only particle geometry/stratification levels respectively. figure 6 shows the effect of chemical pre-treatment and fibre geometry/stratification on the moe of the cbpbs produced. it was observed that cbpbs pre-treated with cacl2 had the highest values of moe followed by boards produced with pre-treated al2(so4)3 while boards with no treatments had the lowest moe values. comparing the overall means for each geometry/stratification of fibre, cbpbs produced using the sawdust/fibre/sawdust had the highest mean followed by cbpbs produced with fibres only. the lowest values of moe were observed in cement-bonded boards produced with no treatment. figure 4: effect of pre-treatment on mor and moe of cement-bonded particle boards. figure 5: effect of chemical treatments and fibre geometry on mor of cement-bonded particle boards. 0 5 10 15 20 25 30 35 40 cacl2 al2(so4)3 no treatment cacl2 al2(so4)3 no treatment mor moe n /m m 2 0 2 4 6 8 10 12 s-f-s f-s-f s only f only s-f-s f-s-f s only f only s-f-s f-s-f s only f only cacl2 al2(so4)3 control m o r ( n /m m 2 ) production factors 38 figure 6: effect of different treatment and fibre geometry on moe of cement-bonded particle boards. 3.2 results of analysis of variance the results of analysis of variance carried out on the effects of pre-treatment, fibre geometry and fibre stratification on cement-bonded particle boards were significant at 0.05% probability level (table 2). this implies that pre-treatment chemical additives, fibre geometry and fibre stratification has impact on the water absorption, thickness swelling, modulus of rupture and modulus of elasticity of cement bonded particle boards. this result agrees with the work of frybort et al. (2008) that particle geometry influences almost all properties of cement-bonded particle boards. separation of means of the different pre-treatment and geometric particle sizes was carried out using duncan multiple range test as presented in table 2. the effects of cacl2 and al2(so4)3 were not significantly different for water absorption and thickness swelling on cement-bonded particle boards. however, cbpbs pre-treated with al2(so4)3 has the lowest values for water absorption and thickness swelling while cbpbs with no pre-treatment has the highest values for water absorption and thickness swelling. this implies that al2(so4)3 is the best pre-treatment additives for cbpbs against water absorption and thickness swelling. the mean values of the strength properties of cbpbs shows that mor and moe with cacl2 treatment had the highest value while the lowest mean value for mor and moe was observed in cbpbs with no pre-treatment. therefore, the best pre-treatment for cbpbs production is cacl2. the results of the particle geometry/stratification presented in table 2 shows that cbpbs produced with sawdust/fibre/sawdust particle geometry stratification had the highest mean value and were significantly different from other particle geometry/stratification. table 1: analysis of variance on the physical and mechanical properties of cbpbs. source of variation df variance wa ts mor moe pre-treatment 2 8.14* 1.85* 32.74* 23.74* fibre geometry 3 3.54* 1.59* 2.65* 0.31* fibre stratification 6 1.49* 0.92* 3.76* 1.49* error 36 total 47 *significant at 0.05% probability level. 0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 5500 s-f-s f-s-f s only f only s-f-s f-s-f s only f only s-f-s f-s-f s only f only cacl2 al2(so4)3 control m o e ( n /m m 2 ) production factors izekor & erakhrumen /journal of tropical forestry and environment vol. 5. no 01 (2015) 31-40 39 table 2: results of dmrt on pre-treatment, particle geometry/stratification of cbpbs. means in columns with the same superscript were not significantly different (p>0.05) 4. conclusion cement-bonded particle boards were produced using different chemical pre-treatment, particle geometry and stratification. it was observed that modulus of rupture (mor) and modulus of elasticity (moe) were greater in the cbpbs produced using sawdust/fibre/sawdust stratification levels compared to cbpbs produced using other particle geometry/stratification levels. thickness swelling (ts) was lowest in boards produced with sawdust only, this was followed by the sawdust/fibre/sawdust while water absorption (wa) was lower in the sawdust/fibre/sawdust stratification. thus, sawdust/fibre/sawdust particle stratification on the average, produced boards of greater physical and mechanical properties. cement-bonded particle boards produced with pre-treatment were more dimensionally stable and has better strength properties than the untreated cbpbs. pre-treatments increased the mor and moe values and reduced the wa and ts values for boards produced. boards produced with the cacl2 treatment additive had the greatest mor and moe values, while cbpbs produced with al2(so4)3 had the least wa and ts values. therefore, cacl2 treatment additive increased the strength properties of cbpbs while al2(so4)3 increase its resistance to water absorption and dimensional failure. pretreatment, particle geometry and stratification has positive effect on the physical and mechanical properties of cement-bonded particle boards. references ajayi, b. 2005. cement-bonded particle boards manufactured from coffee chaff. journal of applied tropical agriculture, 10(1): 63-66. ajayi, b. 2011. durability characteristic of cement-bonded particle boards form maize stalk residue. journal of forestry research, 18(2): 73-89. amanda, s. and untao, s. 2001. fracture properties of bamboo. composites. part b, 32: 451-459. b.s d373 1989. british standard institution specification for wood chipboard and methods of test for particle board bs. 5669. frybort, s., raimund, m., alfred, t. and muller, u. 2008. cement bonded composites: a mechanical review, 3(2): 602-626. gills, l.s. and onuga, j.e. 1989. a comparative study of the trachery elements of some commercial wood of nigeria. feddes repertorium, 95: 645-655. morteza, n., ebrahim, g. and mohammed, d.g. 2011. the influence of wood extractives and additives on the hydration kinetics of cement paste and cement-bonded particle board. journal of applied sciences, 11: 2186-2192. pre-treatment wa ts mor moe cacl2 14.62 a 2.03 a 8.79 b 3787.60 b al2(so4)3 12.76 a 0.67 a 4.19 a 1202.00 a no-treatment 24.94 b 5.58 a 3.83 a 919.95 a particle geometry/stratification sawdust / fibre / sawdust 12.74 a 1.64 a 6.96 b 2057.60 b fibre /sawdust fibre 16.49 b 6.83 b 5.16 a 1810.50 a sawdust only 24.50 c 1.41 a 5.14 a 1788.30 a fibre only 16.01 b 1.45 a 5.14 a 2223.00 b 40 papadopoulos, a.n. 2008. natural durability and performance of hornbeam cement bonded particle board. technological educational institute of kavala, branch of drama, department of forestry and management of natural environment, laboratory of wood and wood products. tk 66100, drama, greece. wise, l.e., murphy, m. and addieco, a.a. 1946. chloroite holocellulose, its fractionation and bearing on summative wood analysis and on studies on the hemicellulose. paper trade journal.122: 35-43. xu, q. and stark, j. 2005. early hydration of ordinary portland cement with an alkaline shotcrete accelerator. advances in cement research, 17(1): 1-8. yu, y., fei, b.h., wang, h.v. and tian, g.l. 2011a. longitudinal mechanical properties of cell wall of masson pine (pinus massoniana lamb) as related to moisture content: a nanoindentation study. holzforschung, 65(1): 121-126. yu, y., jiang, z.h., fei, b.h., wang, g. and wang, h.k. 2011b. an improved microtensile technique for mechanical characterisation of short plant fibre. a case study of bamboo fibres. journal of natural science, 46: 739-746. the association of environmental changes and the replacement of mosquito fauna in the colombo district, sri lanka priyangika, de silva, jayatunga-katuwawalage & wickramasinghe/journal of tropical forestry and environment vol. 4, no 01 (2014) 59-66 59 the association of environmental changes and the replacement of mosquito fauna in the colombo district, sri lanka b.a.s. priyangika 1 , b.g.d.n.k. de silva 1 *, d.p.w. jayatunga-katuwawalage 1 and m.b. wickramasinghe 2 1 department of zoology, university of sri jayewardenepura, nugegoda, sri lanka. 2 retired entomologist, anti-malaria campaign, colombo 5, sri lanka. date received: 18-01-2013 date accepted: 08-04-2014 abstract a mosquito survey was carried out for 8 months between october 2009 and may 2010 in 12 randomly selected urban (6) and semi-urban (6) areas in the colombo district of sri lanka. thirty eight mosquito species were identified from which anopheles interruptus, an. pseudojamesii, aedes stevensoni, ae. edwardsi, ae. vittatus, culex barraudi, cx. fatigans, cx. univittatus, cx. aculeatus, cx. purplexus, cx. spiculosus, cx. quadripalpis, cx. halifaxi, uranotaenia atra, ur. unguiculata were new findings that were not recorded during a previous survey conducted in 1981-1982 in the same locations. rainfall had a direct relationship (p=0.000) with the distribution and the density of mosquitoes. unplanned urbanization, anthropogenic activities and irregular or non-disposal of domestic waste products may have led to population replacement of the mosquito fauna in these locations. keywords: environmental changes, mosquito fauna, sri lanka __________________________________________________________________________________ 1. introduction mosquitoes are insects of the order diptera and family culicidae (service, 2004). there are about 4,000 known mosquito species distributed worldwide (who, 2007). however, less than 10% are regarded as efficient vectors of diseases which directly or indirectly cause a severe impact on human health and welfare. anopheles culicifacies is the major vector of malaria in sri lanka while an. subpictus, under favourable ecological conditions acts as a secondary vector. several other anophelines including an. annularis, an. barbirostris, an. jamesii, an. nigerrimus, an. peditaeniatus, an. tessellatus and an. varuna occur in the island and several of them can be regarded as potential vectors of malaria (perera et al., 2008). both aedes aegypti and ae. albopictus are vectors of dengue, dengue haemorrhagic fever and chickungunya. culex tritaeniorhynchus, cx. gelidus transmit the japanese encephalitis virus. urban filariasis is transmitted by cx. quinquefasciatus while rural filariasis is transmitted by mansonia annulifera, ma. indiana and ma. uniformis (service, 2004). armigeres subalbatus is a vector of dirofilaria for domestic cats and dogs. chelliah et al. (1986) and chelliah & jayasekara (1981) listed 131 species of mosquitoes belonging to 16 genera recorded from sri lanka. chelliah et al. (1986) subsequently reported 45 species in surveys carried out in the colombo district during the period 1981-1982. during the period of 1982-2009 there has been a shift in the environmental conditions in the * correspondence: nissankakolitha@gmail.com tel: +94 112802914 issn 2235-9370 print/issn 2235-9362 online © university of sri jayewardenepura 60 colombo district. internal migrations due to rapid development of industries, education and increased school attendance, garment factories, occupational distribution, decrease of agricultural lands, increase of slum areas, urbanization and establishment of head offices of ministries and widening of the parliament complex and office quarters in colombo had caused severe impacts on the environment. all such changes may have indirectly resulted in climatic change leading to a changing of breeding habitats of mosquitoes. amerasinghe et al. in 1994 conducted a study in the area of the mahaweli project in order to check and compare breeding patterns of ground water mosquitoes before and after irrigation according to the changing of breeding habitats. the present study focused on assessing changes in the mosquito fauna in the localities previously surveyed in the colombo district, sri lanka by chelliah et al. (1986). 2. materials and methods 2.1 the study area investigations were carried out in 12 randomly selected semi-urbanized areas namely, beddagana, battaramulla, madiwela, pelawatte, thalapathpitiya, thalawathugoda, and urbanized areas namely, ethulkotte, kotte, nawala, nugegoda, pitakotte, welikada in the colombo district of sri lanka. fig. 1: townships and villages of the study area in the colombo district. star denotes the parliamentary complex 2.2 mosquito surveys mosquito surveys were carried out fortnightly during the period october 2009 to may 2010. both adult and larval collections were made. a total of 30 houses and the surroundings were investigated between 05.00-21.00 hours. adults were gathered by cattle-baited net-trap parliament complex diyawanna oya …… …… …... ,,,,, ,,,,, ,,,,, +++ +++ +++ …… …… …… ,,,,, ,,,,, ,,,,, +++ +++ +++ marshy land paddy field 61 and exit/inlet window trap collections. resting mosquitoes were also collected from vegetation with hand nets and from domestic animals using aspirators. larval collections were made using earthenware pot-traps and ovitraps. larvae from streams were collected by dipping with a standard ladle and larvae breeding in artificial containers were gathered using a dropper. representative sample of adults, third and fourth stage larvae were identified using morphotaxonomic keys of amerasinghe et al. (1992) and col & sewel (1933, 1934). the first and second stage larvae were reared in the laboratory to third and fourth stages and pupae to adults respectively which were then identified morphologically. 3. results thirty eight species of mosquitoes belonging to seven genera and 11 sub-genera were collected during the study period, of which 18 species are medically important (tables 1 and 2). twenty-three species of mosquitoes were commonly recorded both in the previous and the present surveys in the same localities (table 1). mosquito species totaling 15 in the present study were not recorded in the previous survey while 21 species collected in the previous survey were not found in the present survey (table 2). culex quinquefasciatus was the predominant species, constituting 22.58% (table 3) and was particularly dense in the urbanised areas in the colombo district. during the study period the ambient temperature and humidity ranged from 27.59 0 c-29.04 0 c and 66%-86%, respectively (fig. 2). p-values obtained using minitab 14 for mosquito percentage in relation to rainfall, humidity and temperature amounted to p=0.000, 0.076 and 0.678 respectively. table 1: mosquito species commonly found in previous (1981-1982) and present (2009-2010) surveys in colombo district. 1. anopheles(ano) barbirostris 9. ae. (stg) albopictus 17. cx. (cux) sitiens 2..an. (ano) nigerrimus 10. armigeres (arm)subalbatus 18. cx. (cux)tritaeniorhynchus 3. an. (ano) peditaeniatus 11. culex (cux) fuscocephala 19. cx. (cux) whitmorei 4. an. (cel) jamesii 12. cx. (eum) brevipalpis 20. ficalbia minima 5. an. (cel) maculatus 13. cx. (lop) infantulus 21. mansonia (mnd)annulifera 6. an. (cel) pallidus 14. cx. (lop) minutissimus 22. ma. (mnd) indiana 7. an. (cel) subpictus 15. cx. (cux) gelidus 23. ma. (mnd) uniformis 8. aedes (stg) aegypti 16. cx. (cux) quinquefasciatus*  medically important species table 2: replacement of mosquito species found in the colombo district during 1981-1982 survey and 2009-2010 (present) survey. mosquito species exclusively recorded in 1981-1982 survey mosquito species recorded exclusively in 2009-2010 survey 1. anopheles (cel) tessellatus 1. an. (ano) interruptus 2. an. (cel) vagus 2. an. (cel) pseudojamesii 3. aedes (fin) gubernatoris 3. ae. (fin) stevensoni 4. ae. (adm) pipersalatus 4. ae. (stg) edwardsi 5. ae. (adm) vexans 5. ae. (stg) vittatus 6. ae. (neo) lineatopennis 6. cx. (lut) halifaxi 7. ae. (ver) pseudomediofasciatus 7. cx. (lop )aculeatus 62 (adm) sub genus aedimorphus (ano) sub genus anopheles (arm) sub genus armigeres (cel) sub genus cellia (coq) sub genus coquillettidia (cui) sub genus culiciomyia (cux) sub genus culex (eto) sub genus etorleptiomyia (eum) sub genus eumelanomyia (fin) sub genus finlaya (lop) sub genus lophoceratomyia (lut) sub genus lutzia (mim) sub genus mimomyia (mnd) sub genus mansonioides (neo) sub genus neomelaniconio (pfc) sub genus pseudoficalbia (stg) sub genus stegomyia (tox) sub genus toxorhynchites (ura) sub genus uranotaenia (ver) sub genus verrallina table 3: total numbers and percentages of adults and larvae of each mosquito species collected from the colombo district in the present survey (2009-2010). species total adults & larvae (%) species total adults & larvae (%) 1. an. (ano) barbirostris 8 0.02 20. cx. (lop) aculeatus 2 0.006 2. an. (ano) nigerrimus 783 2.57 21. cx. (lop) spiculosus 1 0.003 3. an. (ano)peditaeniatus 11 0.03 22. cx. (lop) quadripalpis 1 0.003 4. an.(ano) interruptus 859 2.82 23. cx. (cux) fuscocephala 1 0.003 5. an.(cel) jamesii 10 0.03 24. cx. (cux) gelidus 4,851 15.94 6. an.(cel) maculatus 60 0.19 25. cx. (cux)quinquefasciatus 6,780 22.58 7. an.(cel) pallidus 112 0.36 26. cx. (cux )sitiens 2 0.006 8. an.(cel) subpictus 4 0.01 27. cx.(cux)tritaeniorhynchus 4,335 14.25 9. an.(cel)pseudojamesii 90 0.29 28. cx. (cux) whitmorei 21 0.06 10. ae.(fin) stevensoni 2 0.006 29. cx. (cux) barraudi 17 0.05 11. ae.(stg) aegypti 508 1.67 30. cx. (cux) fatigans 4 0.01 12. ae.(stg) albopictus 5,740 18.87 31. cx. (cux) purplexus 2 0.006 13. ae.(stg) edwardsi 7 0.02 32. cx. (cux) univittatus 23 0.07 14. ae.(stg) vittatus 15 0.04 33. fi. minima 5 0.01 15. ar.(arm) subalbatus 3,781 12.43 34. ma. (mnd) annulifera 299 0.98 16. cx. (lut) halifaxi 7 0.02 35. ma. (mnd) indiana 415 1.36 17. cx.(eum) brevipalpis 1 0.003 36. ma. (mnd) uniformis 1,510 4.96 18. cx .(lop )infantulus 23 0.07 37. ur. atra 8 0.02 19. cx.(lop)minutissimus 27 0.08 38. ur. unguiculata 3 0.009 total 30,418 100 8. coquillettidia (coq) crassipes 8. cx. (lop) spiculosus 9. culex (lut) fuscanus 9. cx. (lop) quadripalpis 10. cx. (cui) nigropunctatus 10. cx. (cux) barraudi 11. cx. (cui) pallidothorax 11. cx. (cux) fatigans 12. cx. (cui) spathifurca 12. cx. (cux) purplexus 13. cx. (cux) infula 13. cx. (cux) univittatus* 14. cx. (cux) pseudovishnui 14. ur. (ura) atra 15. cx. (cux) sinensis 15. ur. (ura) unguiculata 16. mimomyia (mim) hybrida 17. mi. (eto) luzonensis 18. malaya genurostris 19. toxorhynchites (tox) splendens 20. uranotaenia (ura) lateralis 21. ur.(pfc) bicolor 63 table 4: larval habitats of mosquito species collected in the present survey (2009-2010). larval species e a rt h e n w a re p o t t ra p o v it ra p s larval/pupal habitats in d o o r l a rv a e c o ll e c ti o n g ro u n d p o o l w it h a q u a ti c v e g e ta ti o n m a rs h y l a n d s p a d d y f ie ld s r u b b e r ti re s c e m e n t ta n k s g a rb a g e c h a n n e ls p la n t a x il s a rt if ic ia l c o n ta in e rs l a k e s & s tr e a m s w e ll s anopheles interruptus an. nigerrimus aedes aegypti ae. albopictus ae. edwardsi ae. stevensoni ae. vittatus armigeres subalbatus culex aculeatus cx. barraudi cx. brevipalpis cx. fatigans cx. fuscocephala cx. gelidus cx. halifaxi cx. infantulus cx. minutissimus cx. quinquefasciatus cx. sitiens cx. spiculosus cx. tritaeniorhynchus cx. univittatus cx. whitmorei ficalbia minima mansonia annulifera ma. indiana ma. uniformis uranotaenia atra ur. unguiculata x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x 64 month m o s q u it o ( % ), t e m p e r a tu r e ( 'c ), r a in fa ll (m m ), h u m id it y (% ) mayaprmarfebjandecnovoct 90 80 70 60 50 40 30 20 10 0 variable humidity (%) mosquito % temperature ( c) rainfall (mm) plot of mosquito(% ), temperature( 'c) , rainfall(mm), humidity(%) vs month fig. 2: the impact of temperature, rainfall and humidity on the percentage of mosquitoes collected monthly during the current study period 2009-2010. 4. discussion the present mosquito survey was carried out in the same areas previously surveyed by chelliah et al. (1986), during which a total of 44 species representing nine genera were detected. in the previous survey (1981-1982), some of these areas were considered rural, some semi-urban while some were identified as urban. the categories of urbanized, semiurbanized and rural areas used in the current study were based on the official classification specified by the respective municipal or the urban council. during the present study, all the study areas were found to be semi-urban or urban to a greater or lesser extent according to the official classification. the present study covered a total of 30 houses in the same areas while the previous study had investigated a total of 15 houses at each visit. the highest percentage of mosquito species amounting to 22.58% was formed by culex quinquefasciatus breeding in polluted waters. such suitable habitats for profuse breeding of this mosquito species have been created due to disposal of toilet and kitchen waters by the residents of areas in to branches of the “diyawanna oya”, that flow through these areas. cx. gelidus and cx. tritaeniorhynchus, which breed more or less under similar conditions formed 15.94% and 14.25% respectively cx. quinquefasciatus, cx. tritaeniorhynchus and cx. gelidus were found in higher number in urban areas than in semi-urban areas as the water was polluted due to stagnant water bodies in blocked drains and uncovered dilapidated toilet pits. ar. subalbatus being a zoophilic, outdoor mosquito was detected in garbage channels and artificial containers in domestic environments as its main targets are domestic animals such as cats and dogs. outdoor mosquitoes, aedes aegypti and ae. albopictus, formed 1.67% and 18.87% respectively. human activities in these areas had created artificial container habitats suitable for breeding of these two species despite massive campaigns of source reduction been conducted by municipal councils and other government institutions. 65 a total of 2,250 of medically important adult female mosquitoes were collected from human dwellings within 12 months in 1981-1982 period which had drastically reduced to a value of 1,603 during eight months study period of the current study, within the same area after 27 years. rainfall is a major climatic factor that creates habitats for mosquito breeding. the current study clearly indicated a significant relationship (p=0.000) between mosquito density and rainfall. mean monthly rainfall for 1981-1982 and 2009-2010 periods were 156.3 mm (climatic data, 1981-1982department of meteorology, sri lanka) and 264.1mm (climatic data, 2009-2010: department of meteorology, sri lanka), respectively. mean rainfall of the study area had much increased within the past 27 years. the respective p values for humidity and temperature with mosquito density, p=0.076 and 0.678 respectively showed no relationship and hence they could not be considered as significant climatic factor changes accounting for mosquito density, within the study area during the study period. it is noteworthy that a study conducted in saudi arabia (alshehri, 2013) has shown that there is a strong correlation between ae. aegypti mosquito density and climatic factors of temperature and relative humidity. comparison of the mosquito population compositions of the two surveys clearly shows the changes taken place of mosquito species in the colombo district within a span of 27 years. it seems to have been caused by changes in the environment leading to creation of suitable breeding habitats for some mosquito species. human population in the colombo district had increased to 788,759 from 1981 to 2009 due to internal migration (sri lanka, ministry of finance and planning, department of census and statistics, 2009). even though the recent development projects spearheaded by the government (from 2009), (“maga neguma”road development, “gama neguma”build houses and home gardens, “diwi neguma” agriculture etc.) have improved the quality of life to some extent, the results of the present study are indicative that unplanned urbanization, town development, destruction of vegetation, filling marshes, irregular or non-disposal of house-hold waste products such as artificial containers, polythene bags, yoghurt cups etc. are major contributory factors for breeding of vector mosquito species of serious human diseases. breeding habitats formed due to these activities for non-vector mosquitoes too would form a health problem as their bites affect humans physically and mentally. similar studies conducted elsewhere (rejmánková et al., 2010) have indicated that in marshes, the replacement of a certain mosquito by another can be due to changes in vegetations caused by increasing of nutrients from agricultural practices. the human induced changes in wetland habitats combined with habitat selection by mosquito females can lead to replacement of a less efficient disease vector by a more efficient one. the present study confirms that the mosquito replacement detected in the study area after 27 years of time is due to environmental change caused by urbanization in the form of increased mosquito breeding habitats. 5. conclusion thirty eight mosquito species were identified of which anopheles interruptus, an. pseudojamesii, aedes stevensoni, ae. edwardsi, ae. vittatus, culex barraudi, cx. fatigans, cx. univittatus, cx. aculeatus, cx. purplexus, cx. spiculosus, cx. quadripalpis, cx. halifaxi, uranotaenia atra and ur. unguiculata were not recorded previously in the period 1981-1982 from the same locations. twenty one species which were recorded in the previous study 66 (1981-1982) were not recorded in this survey. this mosquito replacement may be a result of human activities which include unplanned urbanization together with creation of unattended stagnant water bodies and discarded receptacles which spontaneously become mosquito breeding habitats. there were 18 medically important vector mosquitoes recorded reiterating 16 previous records in the study area indicating that attention should be paid for stringent measures adopted to control vector mosquitoes in the colombo district. 6. acknowledgements the authors wish to thank officers in the sugarcane research institute, medical research institute, anti filariasis unit, anti malaria campaign and dengue control unit for the support given in acquiring data as well as in identifying mosquito species. references alshehri, m.s.a., 2013. dengue fever outburst and its relationship with climatic factors. world applied sciences journal, 22(4):506-515. amerasinghe, f.p., amerasinghe, p.h., karunaratne, s.h.p.p., peiris, j.h.m., ratnayake, c.b., tsai t.f., 1992. japanese encephalitis in sri lanka: the study of an epidemic: vector incrimination, porcine infection and human disease. transactions of the royal society of tropical medicine and hygiene, 86(3):307-313. amerasinghe, f.p., indrajith, n.g., 1994. post irrigation breeding patterns of ground water mosquitoes in an area of the mahaweli project, sri lanka. journal of medical entomology, 31:516-523. chelliah, r.v., jayasekara, n., 1981. an annotated checklist of mosquitoes of sri lanka, department of entomology, medical research institute, colombo 8, mab-unesco – man and biosphere national committee for sri lanka, publication no. 8. published by the national science foundation, colombo 07, sri lanka. chelliah, r.v., jansen, c.g., jayasekara, n., pathmanathan, s., 1986. mosquito studies in sri jayewardenepura-the new capital of sri lanka. mosquito borne diseases bulletin, 2(4), 87-93. col, l., sewel, r. b. s., 1933. the fauna of british india including ceylon and burma, diptera, vol. v, family culicidae, tribes anophelini. today and tomorrow’s printers & publishers, new delhi-110005. col, l., sewel, r. b. s., 1934. the fauna of british india including ceylon and burma, diptera, vol. v, family culicidae, tribes megarhinini and culicini. today and tomorrow’s printers & publishers, new delhi-110005. ministry of finance & planning, department of census and statistics, 1981. census of population and housing, population by sex in rural areas and towns of aga divisions colombo, sri lanka. district report, vol. 1: part 1. perera, m.d.b., hemingway, j., karunaratne, s.h.p.p., 2008. multiple insecticide resistance mechanisms involving metabolic changes and insensitive target sites selected in anopheline vectors of malaria in sri lanka. malaria journal, 7:168. rejmánková, e., 2010. marshes, mosquitoes and malaria and what about nutrients. sws research brief 0001. service, m.w., 2004. medical entomology for students, 3 rd edition, the press syndicate of the university of cambridge, cambridge, united kingdom, pp.1-73. who, 2007. anopheline species complexes in south and south-east asia, world health organization, regional office for south-east asia, searo technical publication no: 57. http://www.sciencedirect.com/science/journal/00359203 http://www.sciencedirect.com/science/journal/00359203 http://www.sciencedirect.com/science?_ob=publicationurl&_tockey=%23toc%2313100%231992%23999139996%23489614%23flp%23&_cdi=13100&_pubtype=j&view=c&_auth=y&_acct=c000054817&_version=1&_urlversion=0&_userid=9454469&md5=915965b4e43b1789b690cef8511ce348 wijesekara and manage /journal of tropical forestry and environment vol. 7, no. 02 (2017) 71-84 71 in vitro screening of, antibacterial antifungal and cytotoxicity activities in crude extract of freshwater cyanobacterium oscillatoria sp. w.a.m.a. wijesekara and p.m. manage* center for water quality and algae research, department of zoology, university of sri jayewardenepura, gangodawila, nugegoda, sri lanka. date received: 25-07-2017 date accepted: 01-12-2017 abstract cyanobacteria, highly diverse group of prokaryotes are recognized as a potent source of biologically active compounds with antiviral, antibacterial, antifungal, and anticancer properties.the aim of the present study was to screen antibacterial, antifungal and cytotoxic activities of intracellular secondary metabolites of freshwater cyanobacterium oscillataria sp. cyanobacterium oscillatoria sp. was isolated from senanayaka samudraya reservoir (70 11’ 37.370n 810 31’ 47.130e), sri lanka.in vitro antibacterial and antifungal activity of oscillatoria sp. was screened against grampositive methicillin-resistant staphylococcus aureus (mrsa) atcc 25923, bacillus anthracis and gram-negative pseudomonas aeruginosa (atcc 25853), salmonella typhi and escherichia coli (atcc 25922) and fungi, unicellular candida albicans (atcc 60192) and candida tropicalis using agar disc diffusion method.the minimum inhibitory concentrations (mic), minimum bacteriocidal concentration (mbc), minimum fungicidal concentrations (mfc) and cytotoxic effects (brine shrimp bioassay) of oscillatoria crude extract were determined. 10% and 60% of biomass was extracted with hexane and methanol respectively.gas chromatography-mass spectrometry (gc-ms) was used to identify compounds in the crude extract. the highest antibacterial and antifungal activity of crude extract were detectedin methanol extract against s.aureus (19±2 mm)and c.albicans (10±1 mm) within 24 hours wherein the hexane extract, antibacterial activity was detected only for s. aureus and mean diameter of inhibition zone was 11±1mm within 24 hours.the lowest mic of methanol extract against s. aureus wasfound as 156.25 µg/ml. the lowest mbc and mfc of methanol extract againsts. aureus and c.albicans were 0.63 mg/ml and 1.25mg/ml respectively. lethal concentration, 50% of the crude extract against brine shrimp was recorded at 2.50 g/l, 1.25 g/l and 0.625 g/l for 6, 12, 24 hrs intervals respectively. gc-ms analysis revealed that the methanol crude extract of oscillatoria sp. contains important fatty acid namely hexadecanoic acid methyl ester, methyl tetradecane and 13-tetradecanoic acid and n-hexane extract contains bis (2-ethylhexyl hydroxypyridine oxide, 1 2-benzenedicarboxylic acid mono (2-ethylhexyl) ester, phthalic acid 6ethyl-3-octyl heptyl ester and phthalic acid dodecyl nonyl ester which may possess antibacterial and antifungal properties. keywords:oscillatoria sp., mfc, mic, mbc, cytotoxicity 1. introduction over the past decades, an alarming number of clinically efficacious antibiotics have become less effective due to the direct implications in human morbidity and mortality, leading to the development of microorganisms that are resistant to antibiotics (liyanage and manage, 2016). 72 consequently, an increase in the failure of chemotherapeutic and antibiotic resistance by pathogenic microorganisms has led to the screening of several other alternative sources for potential antimicrobial activity (osman et al., 2011). eventually, researchers came up with a rational alternative for synthetic drugs; bioactive compounds derived from cyanobacteria and algal extracts and it has always been recognized that humans, animals, and plants benefit from cyanobacteria and algae and their extracts (chojnacka et al., 2012). cyanobacteria are morphological, physiological, and metabolically a diverse group which originated 3.5 billion years ago (kaushik and chauhan, 2008;sethunga and manage, 2009). they are not only widespread in freshwater, marine and terrestrial ecosystems but also found in extreme habitats such as hot water springs, hypersaline localities, freezing environments and arid deserts (wijesekara and manage, 2016; manage et al., 2009a). to survive in a highly competitive environment, often exhibiting widely fluctuating chemical and physical parameters, they have developed defensive and adaptive strategies, including the synthesis of a tremendous diversity of compounds from different metabolic pathways (yadav et al., 2010). recent scientific studies have documented that various strains of cyanobacteria are known to produce intracellular and extracellular metabolites with diverse biological activities such as antibacterial, antifungal, cytotoxic, algaecide, immunosuppressive and antiviral chemicals (ghasemi et al., 2003; jaki et al., 1999; manage et al., 2009b).the majority of them were originated from the filamentous genera lyngbya, oscillatoria, and symploca (williams et al., 2001; osswald et al., 2007; grindberg et al., 2008,) and a high degree of diversity in the bioactivities due to the presence ofsecondary metabolites. recent studies on biologically active secondary metabolites from cyanobacteria led to the identification of a wide range of antibiotic compounds (singh et al., 2005). ethyl acetate extract of spirulina platensis consisted of heptadecane and tetradecane which can inhibit some gram +ve and gram-ve bacteria and candida albicans(ozdemir et al., 2004). el-sheekh et al. (2005) showed that phenolic compounds from nostoc muscorum exhibited antagonistic activity against gram +ve and gram-ve bacteria. ghasemi et al. (2003) isolated substances belonging to groups of peptides, polypeptides, amides and alkaloids from fischerella ambigua, anabaena spp. which produce a number of bioactive compounds, mostly lipopeptides that have antibiotic, antialgal, anticancer, antiinflammatory, cytotoxic and enzyme-inhibiting effects (burja et al., 2001; fujii et al., 1997). thus the present study was aimed to screen the antibacterial and antifungal activity o f the isolated oscillatoria sp. against both gram positive and gram negative human pathogenic bacteria and fungal species and evaluate the cytotoxicity effect against artemia. finally, to identify the individual components of their methanol and hexane extract by gas chromatography (gc) coupled with a mass spectrometer (ms). 2. material and methods 2.1 isolation of cyanobacteria cyanobacteria used in this study was isolated fromfreshwater sample collected from the senanayake samudraya reservoir (70 11’ 37.370 n 810 31’ 47.130 e), sri lanka. water samples were brought to the laboratory in an aseptic condition and the bg11 medium was used for isolation and maintenance of the cyanobacterium (manage et al., 2001; manage et al., 2009). unifilamentous oscillatoria sp. was isolated using a pasture pipette following the spread plate method (manage et al., 1999). isolated oscillatoria sp. in bg-11culture was maintained without aeration at 25±1°c, at a light intensity of 2,000-3,000 lux (10 μmol m-2s-1) provided by cool white tubes and with a light/dark cycle of 18 h /6 h. bacterial contamination states were confirmed by standard tyg (tryptone, yeast extract and glucose) protocol (vaara et al., 1979). the fernbach and mass cultures of oscillatoria sp. wijesekara and manage /journal of tropical forestry and environment vol. 7, no. 02 (2017) 71-84 73 was prepared and mass culture was grown under laboratory condition for a period of 30 days in 10 litres of bg 11 medium. the exponential growth phase of the culture was determined by chlorophylla content and the culture was harvested within 1015 days by centrifugation at 10°c, 6,500 rpm for 10 minutes. 2.2 preparation of oscillatoria crude extract one gram of dried biomass was ground to fine powder and extracted using two different extraction solvent; hexane and methanol. the powder form of biomass was dissolved in 100 ml of nhexane and the cells were broken in an ultrasonic water bath for 7 min at 35 khz. then, the biomass was extracted under magnetic stirring for 2 h following centrifugation at 4,100 rpm for 10 min at 10°c and then the supernatant was separated from the residue. this step was repeated three times. the biomass residue was dried overnight and further extraction was carried out with 3 x 150 ml meoh. complete removal of solvent was achieved by rotary evaporation at 40o c (ika hb 10, germany). the meoh extract and hexane extract were weighed and kept in sealed vials in -20°c freezer for further use. to prevent oxidation, all steps were carried out in the dark while the flask was covered with aluminium foil. 2.3 pathogenic bacteria and fungal strains screening for antibacterial and antifungalactivity of methanol and hexane extract was carried out using human pathogenic gram-positive; staphylococcus aureus(mrsa) atcc 25923 andbacillus anthracis and gram-negative; pseudomonas aeruginosa (atcc 25853), escherichia coli (atcc 25922) and salmonella typhiand fungi; unicellular candida albicans (atcc 60192)and candida tropicalis obtained from department of microbiology, faculty of medical sciences, university of sri jayewardenepura. nutrient agar (na) was used for the cultivation of target bacteria and all bacteria cultures were incubated at 37ºc for 24 hrs and fungal species were grown in potato dextrose agar (hi-media) at ambient temperature for 72 h. 2.4 antimicrobial assay disc diffusion method for antimicrobial susceptibility test was carried out according to the standard method given by mundt et al. (2001) to assess the presence of antibacterial and antifungal properties of the extract. bacterial and fungal cultures (which have been adjusted to 0.5 mcfarland standard), were used for lawn muller hinton and pda agar plates respectively. the plates were dried for 15 minutes and then used for the sensitivity test. the discs which had been impregnated with a series of crude extracts (5µg/disc, 400 µg/disc) were placed on the muellerhinton agar and potato dextrose agar surface. each test plate comprised four discs. one positive control (ciprofloxacin (antibacterial), amphotericin b (antifungal) 5µg/disc) which was a standard commercial disc, one negative control (dmso 100%), and two treated discs.the petri dish was kept at 4°c about 3 h for pre-diffusion. afterwards, the plates were incubated for 24 h at 37°c for bacteria and fungi in an inverted position. at the end of the incubation period, the inhibition zones were measured using callipers and expressed as the diameter of the clear zone, with the diameter of the paper disc. the test was repeated three times to ensure reliability. 74 2.5 determination of relative percentage inhibition the relative percentage inhibition with respect to positive control was calculated by using the following formula. relative percentage of inhibition of test extract = 100×(𝑎−𝑏) 𝐶 (1) where: a=inhibition zone of test extract b=inhibition zone of the solvent c=inhibition zone of the standard drug (ciprofloxacin, amphotericin b ) 2.6 ttc (2,3,5triphenyl tetrazolium chloride) bioassay figure 1: preparation of the microtiter plate for mic estimation against test bacterial and fungal species. c1-highest concentration of crude extract (2.5 mg/ml), phighest concentration of standard antibiotic (cloxacillin 2.5 mg/ml) bcontrol (nutrient broth, and bacteria suspension) negative (n)control (pbs buffer, bacteria suspension). the minimum inhibitory concentration of crude extract of oscillatoria sp. was determined by broth dilution methods using 96-well microtiter plates against gram-positive bacteria (s. aureus,b. anthracis) gram-negative bacteria (p. aeruginosa, e. coli, s. typhi) and fungi (unicellular c. albicans (atcc 60192), c.tropicalis). for the broth dilution method, inocula of the microbial strains were prepared from the overnight nutrient broth cultures for bacteria and potatoes dextrose broth for fungi. bacterial and fungal suspensions were adjusted to 0.5 mcfarland standard turbidity. the crude extract was dissolved in pbs buffer to get stock solutions c1 (2.5 mg/ml) and the positive control was prepared using standard cloxacillin (2.5 mg/ml) for bacteria andamphotericin b (2.5 mg/ml) for fungi. different concentrations of extract were prepared using two-fold dilution techniques and transferred to each well of 96 well plate. bacterial and fungal suspension and pbs buffer were used as negative control (n-control) and pbs, nutrient broth or pda broth with bacteria and fungi suspension was used as b control. 100 μl of the standardized bacterial and fungi suspension was pipetted into all wells from 1st row to 11th row. the well h12 was kept empty as a photometric blank (figure 1) and the plate was incubated at 37°c for 24 h.after the incubation, microbial growth was determined by adding 20 μl of 0.5% triphenyl tetrazolium chloride (ttc) aqueous solution following 30 min incubation (sartoratto et al. 2004). c1 b-control. c1 b-control. c1 b-control. c1 b-control. p n-control. p n-control. p n-control. p blank 1 2 3 4 5 6 7 8 9 10 11 12 a c d e b f g h wijesekara and manage /journal of tropical forestry and environment vol. 7, no. 02 (2017) 71-84 75 minimum inhibitory concentration (mic) was defined as the lowest concentration of the samples inhibiting visible growth (red coloured solution of the wells) after addition of ttc. the od was measured using multiskan ex, microplate reader at 480 nm. 2.7determination of minimum bactericidal concentration (mbc) and minimum fungicidal concentration (mfc) the mbc/mfc is defined as the concentration of the antimicrobial agent that results in the 99.9% reduction in cfu/ml, compared with the organism concentration in the original inocula. the mbc was determined by using the test plates which were previously used for mic test. 50 µl aliquots from each well were spread separately on the entire surface of the sterile nutrient agar and pda plates with the help of sterile glass spreader and incubated in inverted position overnight at 37oc for bacteria and three days for fungi at room temperature. the test was run in duplicate and the aliquots of wells that were not given a visible growth defined the mbc/mfc of the compound. 2.8brine shrimp cytotoxicity assay brine shrimp lethality test was carried out according to the method described by piyathilaka et al., (2015) with minor modification. brine shrimp eggs (artemia salina) obtained locally were hatched in artificial seawater (38 g/l) for 24 hours. following 24 hr of hatching, 10 larvae were collected and transferred into 24-microwell plate. a stock solution (500 mg/ml) of the extract was prepared by suspending dried extract in salt water and the suspension was mixed for 5 min. different concentrations of extract was prepared from stock solution (500, 250, 50, 25, 12, 6 mg/ml) and 5 ml was transferred into each well. following 24 hr of incubation, the number of dead larvae was counted with the aid of a light microscope (labomed, usa) and then the lethal concentration (lc50) was determined. 2.9gas chromatography/mass spectrometry (gc/ms) the volatile constituents of methanol and hexane extracts of oscillatoria sp. were analysed by gc/ms using a thermo scientific capillary gas chromatography (an agilent technologies 7890 a gc/5975c mass selective detector (msd). the dried extract was re-dissolved in extracting solvent and subjected to gc/ms analysis. the gc/ms analysis was performed on a 30-m × 0.25-mm i.d. db225ms capillary column under the following conditions: oven temperature program from 40 °c (3 min) to 280° c at 5° c/min, then isothermal at 280ºc for 5 min, flow rate of carrier gas (helium) was 1 ml/min, the injected sample volume was 1 μl, splitless injection technique, and ionization energy of 70 ev in the electron ionization (ei) mode. identification was carried out by comparing the retention indices and fragmentation pattern in mass spectra. the antibacterial activity of the methanol and hexane extracts of oscillatoria sp. is presented in table1.the extracts showed different degrees of antimicrobial activity against test microorganisms. the antibacterial and antifungal activity of the extracts were classified based on the average zones of inhibition into four levels namely resistant (iz=6-16 mm), moderate activity (iz=16-20 mm) and strong activity (iz=22< mm) against 400 µg/disc concentration according to the national committee for clinical laboratory standards guidelines(nccls). the methanol extract showed moderate antibacterial activity against all the test bacteria and low activity against fungi. nhexane extract exhibited low antibacterial activity only against s. aureus. 76 3. result and discussion table 1: antibacterial and antifungal activities (average zone of inhibition in mm±sd) of the methanol and hexane crude extracts of the oscillatoria sp. within 24 hr by disc diffusion assay. pathogenic bacteria and fungi bacteria oscillatoria sp. crude extract diameter of inhibition zone (positive control) diameter of inhibition zone methanol extract hexane extract 400 µg/disc 5 µg/disc 400 µg/disc 5 µg /disc 5 µg /disc s.aureus 19 mm ± 2 9 mm ± 1 14 mm ± 1 7 mm ± 1 30 mm ± 1 p.aeruginosa 16 mm ± 1 12 mm ± 2 nd nd 38 mm ± 1 s.typhi 16 mm ± 1 7 mm ± 1 nd nd 30 mm ± 1 e.coli 16 mm ± 1 10 mm ± 1 nd nd 40 mm ± 1 b.anthracis 17 mm ± 1 10 mm ± 1 nd nd 25 mm ± 1 fungi c.albicans 10 mm ± 1 nd nd nd 15 mm ± 1 c.tropicalis 9 mm ± 1 nd nd nd 14mm ± 1 positive control: 5 gµ/disc of ciprofloxacin to bacteria and amphotericin b to fungi nd: not detected figure 2: relative % inhibition of methanol extract and n-hexane extract of oscillatoria sp. against positive control (black barsmethanol extract, hass barshexane extract). wijesekara and manage /journal of tropical forestry and environment vol. 7, no. 02 (2017) 71-84 77 figure 3: zone of inhibition of methanol crude extractof oscillatoria sp. against test bacteriapositive control (5μg/disc ciprofloxacin), bnegative control, ccrude extract (400 μg/disc), dcrude extract (5 μg/disc) ab. anthracis bp. aeruginosa ce.coli ds. aureus e-s.typphi. figure 4: zone of inhibition of methanol crude extractof oscillatoria sp. against testfungal species.(a methanol extract, bnegative control, cmethanol extract, d-positive control (amphotericin b ), aoscillatoria sp. methanol extract against, c.tropacalis, b-oscillatoria sp. methanol extract against c.albicans). a a b a d a c b a b a c d a b c d b a b c d c a b c d d a d c b a b c d a b e 78 the figure shows relative % inhibition of methanol extract and n-hexane extract of oscillatoria sp. against test bacteria and fungi. the highest relative % inhibition was recorded (68 %) in the methanol extract against b. anthracis. table 2a:minimum inhibitory concentration (mic) and minimum bactericidal concentration (mbc) of oscillatoria sp. crude extractagainst test bacteria species. test microorganisms bacteria species antimirobial susceptible test mic (µg/ml) mbc (μg/ml) s. aureus 156.25 625 p. aeruginosa 312.50 1250 s. typhi 312.50 1250 e. coli 312.50 1250 b.anthracis 312.50 1250 table 2b:minimum inhibitory concentration (mic) and mfc minimum fungicidal concentration (mfc)of oscillatoria sp. crude extract against test fungal species. antimirobial susceptible test fungi species mic (μg/ml ) mfc (μg/ml) c.albicans 312.50 1250 c.tropicalis 625.00 2500 the methanol crude extract was subjected mic assay and showed potent mic and mbc property and the results were correlated with the zone of inhibition recorded by disc diffusion (table 1). on screening the mic activity, the lowest mic was obtained as 156.25 µg/ml against s. aureus followed with 312.50 µg/ml against p. aeruginosa, s. typhi, e. coli and b.anthracis. on the other hand, methanol extract showed lower mbc against s. aureus and theconcentration was 625 µg/ml. figure 5: mean mortality of artemia salina against methanol crude extracts of oscillatoria sp. after 6 hrs, 12 hrs and 24 hrs of incubation. wijesekara and manage /journal of tropical forestry and environment vol. 7, no. 02 (2017) 71-84 79 mean mortality of artemia against oscillatoria sp. methanol crude extract was evaluated (figure 5). ic 50 value of oscillatoria sp. methanol crude extract at 6, 12, 24 hrs recorded 2.5 g/l, 1.25 g/l and 0.63 g/l respectively. similarly, assessment by maruthanayagam et al., (2013) showed for pseudoscytonema sp.and oscillatoria sp. had weak toxicity, while the geitlerinema sp. and o. boryana extracts exhibited stronger toxicity against artemia salina with lc 50 of 32, 61 µg /ml. further, the compounds has lc 50 values lower than ˂10 µg/ml are considered as very actively toxic whereas the lc50 between 100-500 µg/ml is was considered moderately toxic and lc50 values greater than 1000 µg/ml was non-toxic for artemia assay (babajide et al., 2010; meyer et al., 1982). table 3: gc-ms analysis of the different chemical components in methanol and hexane extracts of oscillatoria sp. no methanol extract compounds retention time (min) area (%) 1 methyl tetradecanoate 31.01 0.261 2 13-tetradecynoic acid, methyl ester 34.72 0.128 3 1-butene, 2-ethyl-3-methyl 34.90 0.134 4 hexadecanoic acid, methyl ester 35.12 0.769 hexane extract 5 bis(2-ethylhexyl hydroxypyridine oxide 22.32 0.995 6 1 2-benzenedicarboxylic acid mono(2-ethylhexyl)ester 45.82 1.581 7 phthalic acid 6-ethyl-3-octyl heptyl ester 47.14 0.147 8 phthalic acid dodecyl nonyl ester 48.57 0.169 chemical components in methanol and hexane extract of oscillatoria sp. were analyzed using gas chromatography-mass spectrometry method. table 3 shows the chemical components in methanol and hexane extract. according to the mass spectroscopy reading, most of them are fatty acid compounds with more than 97% similarity. 4. discussion with regard to increasing human pathogenic bacterial and fungal diseases and rising antimicrobial resistance, the current antimicrobial drug development is not adequate to combat bacterial and fungal diseases. in the present study, the potential of isolated cyanobacteria isolate to produce substances inhibiting the growth of some selected human pathogenic bacteria and fungal species were evaluated.it was documented that different screening methods can lead to dissimilar results due to different sensitivities of the methods and permeability of bioactive substances into the test organisms (pawar and puranik, 2008). thus, in the present study antimicrobial screening of intracellular substances, isolated from freshwater cyanobacterium oscillatoria species was carried out using the agar diffusion method and broth microdilution method. high metabolite yield was obtained in the methanol extract (60%) compared with hexane (10%) extract, this may be due to the presence of moderately polar compounds in methanol extract. a similar result was recorded by mundt et al., 2001 for chlorococcus species in methanol extract. it was foundthat high percentage of methanol extracts with positive effects against s. aureus indicated a 80 higher chance of finding antimicrobial chemicals in methanol extracts. the highest effective zone of inhibition by methanol extract of anabaena variabilis against s. aureus, e. coli, p. aeruginosa and s. typhi were recorded by kaushik et al., (2009). in the present study, similar impressed results of antibacterial and antifungal properties were found in methanol extract compared to hexane extract. cyanobacteria belong to the gram-negative bacteria; therefore, their metabolites have stronger activity against gram-positive bacteria and yeasts (mundt et al., 2001). this fact supports the assumption that these metabolites can be produced to protect cyanobacteria themselves from competing for organisms (piccardi et al., 2000; mundt et al., 2001; bhadury and wright, 2004; martins et al., 2008). furthermore, activity against gram-positive bacteria and rare activity against gram-negative bacteria were documented (cannell et al., 1988b; moore, 1996; kreitlow et al., 1999; mundt et al., 2001; svircev et al., 2008; medina-jaritz et al., 2011). in the present study, methanol extract showed strong antibacterial activity whereas hexane extract showed the antibacterial activity only against s. aureus (table 1). previous studies also showed poor antibacterial activity in hexane extract (moore, 1996). however, there are certain drawbacks of the disc diffusion method. aspaper disc retains the active component and does not allow it to diffuse into the muller hinton agar, diffusion of the active compound depends on the starch content of the agar medium, depth of the solid agar medium and diffusion capacity of the active compound. hence, in the present study, broth microdilution assay was used to overcome the practical issues of the disc diffusion assay. broth microdilution assay was carried out using ttc (tri phenyl tetrazolium chloride). use of 2, 3, 5-triphenyltetrazolium chloride (ttc) for determination of mic is possible due to its ability to change the colour of the broth from light yellow to pink. when present with bacteria, ttc act as the artificial electron acceptor, which was changed from colourless to red triphenyl formazan (tpf). ttc is reduced to red formazan which is directly proportional to the viable active cells. the inhibitory effects of oscillatoria sp. extract concentrations were remarkably higher against s. aureus and c.albicans than other test bacteria and fungal species tested which was indicated by the wider diameter of inhibition zones (table 1). the correlation between relative formazan absorbance and relative colony count was more evidenced in s. aureus than in other tested bacteria species, especially in the low values (table 2a), and that may be attributed to the higher activity against gram-positive bacteria to reduce ttc into red formazan, compared to gram-negative species. determination of the mic and mbc of present extracts was apparent for effective antimicrobial property which reasonably correlates with recent records of kaushik et al., (2009) and pramanik et al., (2011). kaushik et al., (2009) reported for effective antimicrobial activity against extracts of cyanobacterial for s. aureus, e.coli, p.aeruginosa and s. typhi with the lowest mic value of 256 μg/ml. in a similar study, pramanik et al., (2011) demonstrated that the mic value for crude extracts of lyngbya, phormidium, oscillatoria and synechocystis against s. aureus, e. coli, b. subtilis was 250 μg/ml whereas 500 μg/ml for p. aeruginosa. further investigation on ethyl acetate extracts of anabaena sp. showed strong antibacterial activity against pathogenic aeromonas species at the lowest mic of 55.30 μg/ ml (abdel-raouf and ibraheem, 2008). the brine shrimp (a. sauna) lethality assay is considered a useful tool for preliminary assessment of cytotoxicity. literature data suggested a good correlation between the brine shrimp assay and some tumour cell lines (soils et al., 1993) as well as hepatotoxic activity (kiviranta et al., 1991). the high ic 50 value recorded in the present study by oscillatoria extract against artemia after 24 hr incubation (650 μg/ml) indicates the low cytotoxic effect of the methanol crude extract. wijesekara and manage /journal of tropical forestry and environment vol. 7, no. 02 (2017) 71-84 81 according to the gc-ms result (table 3), eight compounds were identified and they were constituting 96.45% of the total component. tetradecanoic acid and hexadecanoic acid detected in the present study is to be the common major volatile component in many other cyanobacteria species. the compounds such as tetradecanoic acid and hexadecanoic were found in both algae and plants showed anticancer, antioxidant and antimicrobial activity (bergsson et al., 1999; benkendorff, 2010, galbraith et al., 1971). unsaturated hydroxylated fatty acids and linolenic acid synthesized by cyanobacteria are involved in defence reactions against cohabitants in the biotope (mundt et al 2003). fatty acids are able to change the permeability of the cell membrane, interact with proteins and lipids of the cell membrane, inhibit special enzymes or form a layer around the cells. it was hypothesized by lampe et al., (1998) that lipids kill microorganisms by leading to disruption of the cellular membrane because they can penetrate the extensive meshwork of peptidoglycan in the cell wall without visible changes and reach the bacterial membrane leading to its disintegration. then the chemical found in the methanol extract of oscillatoria sp. is a potential organism to produce pharmaceuticals in near future. 5. conclusion the methanol extract of oscillatoria sp. showed better antibacterial and antifungal activity against both gram-positive and gram-negative human pathogenic bacteria and pathogenic fungi than hexane extract. methanol extract also showed low cytotoxicity according to the artemia bioassay. further, gc-ms result revealed that methanol crude extract contains four fatty acid compounds and antibacterial activity may be due to the presence of fatty acid in the crude extract. an improved knowledge of composition, analysis, and properties of osillatoria sp. with respect to antimicrobial compounds would assist in effort in the pharmaceutical application of this cyanobacteria. acknowledgement the authors wish to thank university of sri jayewardenepura in sri lanka for providing the financial support for the study ( asp/01/re/sci/2015/24). refe rence s abdel-raouf, n. and ibraheem, i.b. (2008). antibiotic activity of two anabaena species against four fish pathogenic aeromonas species. african journal of biotechnology, 7(15). babajide, o.j., mabusela, w.t., green, i.r., ameer, f., weitz, f. and iwuoha, e.i. (2010). phytochemical screening and biological activity studies of five south african indigenous medicinal plantsj. med. plants res. (4): 1924–1932. benkendorff, k. ( 2010). molluscan biological and chemical diversity: secondary metabolites and medicinal 511 resources produced by marine molluscs. biological reviews. 85, 757-775. bergsson, g., steingrímsson, ó. and thormar, h. (1999). in vitro susceptibilities of neisseria gonorrhoeae to fatty acids and monoglycerides. antimicrobial agents and chemotherapy 43:118. bhadury, p. and wright, p. c. (2004). exploitation of marine algae: biogenic compounds for potential antifouling applications. planta. 219(4): 561-578. burja, a. m., banaigs, b., abou-mansour, e., grant burgess, j. and wright, p. c. (2001). marine cyanobacteria -a prolific source of natural products. tetrahedron. 57(46): 9347-9377. 82 cannell, j. p. r.; owsianka, a. m. and walker, j. m. (1988b). results of a large-scale screening programme to detect antibacterial activity from freshwater algae. british phycological journal 23(1): 41-44. chojnacka. k., saeid. a., witkowska. z., and tuhy. l., (2012) biologically active compounds in seaweed extracts the prospects for the application. the open conference proceedings journal. 3(1): 20-28. el-sheekh, m. m., el-shouny, w. a., osman, m. e. h. and el-gammal, e. w. e. (2005). growth and heavy metals removal efficiency of nostoc muscorum and anabaena subcylindrica in sewage and industrial wastewater effluents. environmental toxicology and pharmacology. 19(2): 357-365 fujii, k., sivonen, k., adachi, k., noguchi, k., shimizu, y., sano, h., hirayama, k., suzuki, m. and harada, k.i. (1997). comparative study of toxic and non-toxic cyanobacterial products: a novel glycoside, suomilide, from non-toxic nodularia spumigena hkvv. tetrahedron letters. 38(31): 5529-5532. galbraith, h., miller, t.b., panton, a.m and thompson j.k (1971). antibacterial activity of long chain fatty acids and the reversal of calcium, magnesium ergocalciferol and cholesterol. journal of applied bacteriology 34: 803-813. ghasemi, y., yazdi, m. t., shokravi, s., soltani, n. and zarrini, g. (2003). the antifungal and antibacterial activity of paddy-fields cyanobacteria from the north of iran. journal of sciences, islamic republic of iran. 14(3): 203-209. grindberg, v. r., shuman, f. c., sorrels, m. c., wingerd, j. and gerwick, h. w. (2008). neurotoxic alkaloids from cyanobacteria. morden alkaloids: structure, isolation, synthesis and biology. fattorusso e. and taglialatela-scafati o.: wiley-vch. jaki, b., orjala, j. and sticher, o. (1999). a novel extracellular diterpenoid with antibacterial activity from the cyanobacterium nostoc commune. journal of natural products. 62(3): 502-503. kaushik, p., chauhan, a., chauhan, g. and goyal, p. (2009). antibacterial potential and uv-hplc analysis of the laboratory-grown culture of anabaena variabilis. international journal of food safety, 11: 11-18. kaushik, p. and chauhan, a. (2008). in vitro antibacterial activity of laboratory-grown culture of spirulina platensis. ind. j. microbiol. 48: 348-2. kiviranta, j., sivonen, k., niemelk, s. i., and huovinen, k. (1991). environ toxicol. wat. qual. 6: 423-436. kreitlow, s., mundt, s. and lindequist, u. (1999). cyanobacteria a potential source of new biologically active substances. journal of biotechnology 70: 61-63. lampe, d.j., grant, t.e. and robertson, h.m. (1998). factors affecting transposition of the himar1 mariner transposon in vitro. genetics 149(1): 179-187. (export to ri) liyanage. g.y. and manage. p.m. (2016) occurrence, fate and ecological risk of antibiotics in hospital effluent water and sediments in sri lanka, international journal of agriculture and environmental research, 2(4): 909-935. manage, p.m., edwards, c and lawton, l.a. (2009b). biodegradation of microcystin-lr by natural bacterial populations. interdisciplinary studies on environmental chemistry environmental research in asia: 277–285. manage, p.m., edwards, c., singh, b.k. and lawton, l.a. (2009a) isolation and identification novel microcystin-degrading bacteria. applied environmental microbiology. 75(21): 6924–6928. manage, p.m, zen`ichiro kawabata & shin-ichi nakano (2001) dynamics of cyanophages-like particles and algicidal bacteria causing microcytis aeruginosa mortality. limnology 2: 73-78. wijesekara and manage /journal of tropical forestry and environment vol. 7, no. 02 (2017) 71-84 83 manage, p.m., zen`ichiro kawabata and shin-ichi nakano. (1999). seasonal changes in densities of cyanophage infectious to microcytis aeruginosa in a hypereutrophic pond. hydrobiologia 411: 211-216. maruthanayagam, v., nagarajan, m. and sundararaman, m. (2013). cytotoxicity assessment of cultivable marine cyanobacterial extracts in artemia salina (brine shrimp) larvae and cancer cell lines. toxin reviews, 32(1): 1-9. martins, r.f., ramos, m. f., herfindal, l., sousa, j. a., skærven, k. and vasconcelos, v. m. (2008). antimicrobial and cytotoxic assessment of marine cyanobacteria synechocystis and synechococcus.marine drugs. 6(1): 1–11. medina-jaritz, n.b., pevez-solis, d.r., ruiloba de leon, s.l., rolveraramirez, f.and olveraramírez, r. (2011).antimicrobial activity of the aqueous and methanolic extract of arthrospora maxima, science against microbial pathogens communicating current research and technological advances.a. méndezvilas (ed),©formatex12671271. meyer, b.n., ferrigni, n.r., putnam, j.e., jacobsen, l.b., nichols, d.j. and mclaughlin, j.l. (1982). brine shrimp: a convenient general bioassay for active plant constituents. planta medica, 45(05): 31-34. moore, r. e. (1996). cyclic peptides and depsipeptides from cyanobacteria: a review. journal of industrial microbiology and biotechnology. 16(2): 134-143. mundt, s., kreitlow, s., nowotny, a. and effmert, u. (2001). biochemical and pharmacological investigations of selected cyanobacteria. international journal of hygiene and environmental health. 203(4): 327-334. mundt, s., kreitlow, s., jansen, r. and mundt, s. (2003). fatty acids with antibacterial activity from the cyanobacterium oscillatoria redekei hub 051. journal of applied phycology. 15: 263– 267. osman. m.e.h., aboshady. a.m., elshobary. m.e (2011). production and characterization of antimicrobial active substance from some macroalgae collected from abuqir bay (alexandria) egypt. african journal of biotechnology, 12(49): 6847-6858. osswald, j., rellán, s., gago, a. and vasconcelos, v. (2007). toxicology and detection methods of the alkaloid neurotoxin produced by cyanobacteria, anatoxin-a. environment international. 33(8): 1070-1089. ozdemir, c.y., akyol and alçıtepe.e. (2004). morphological and anatomical studies on two endemic crocus species of turkey area. pak. j. bot., 36(1): 103-113. pawar, s. t. and puranik, p. r. (2008). screening of terrestrial and freshwater halotolerant cyanobacteria for antifungal activities. world journal of microbiology and biotechnology. 24(7): 1019-1025. pedersén, m. and dasilva, e. j. (1973). simple brominated phenols in the blue-green alga calothrix brevissimawest. planta. 115(1): 83-86. piccardi, r., frosini, a., tredici, m. r. and margheri, m. c. (2000). bioactivity in free-living and symbiotic cyanobacteria of the genus nostoc. journal of applied phycology. 12(3): 543-547. piyathilaka, m.a.p.c., pathmalal, m.m., tennekoon, k.h., de silva, b.g.d.n.k., samarakoon, s.r. and chanthirika, s. (2015).microcystin lr induced cytotoxicity and apoptosis in human embryonic kidney (hek 293) and human kidney adenocarcinoma (achn) cell lines microbiology papers in press. published january 29, 2015, as doi:10.1099/mic.0.000046. pramanik, a., sundararaman, m., das, s., ghosh, u. and mukherjee, j. (2011). isolation and characterization of cyanobacteria possessing antimicrobial activity from the sundarbans, the world’s largest tidal mangrove forest. journal of phycology,47(4): 731-743. 84 sartoratto, a.l.m., machado, c., delarmelina, g.m., figueira, c.t.v., duarte marta, l.g. and rehder braz. j.(2004). composition and antimicrobial activity of essential oils from aromatic plants used in brazil. microbiol 35: 275–280. singh, s., kate, b. n. and banerjee, u. c. (2005). bioactive compounds from cyanobacteria and microalgae: an overview. critical reviews in biotechnology. 25(3): 73-95. sethunga. and manage, p.m. (2009). killing of microcystis aeruginosa by the predacious protozoa. first national symposium on natural resource management, sabaragamuwa university sri lanka. 29-30 august, 2009. solis, p.n., wright, c.w., anderson, m.m. (1993). a microwell cytotoxicity assay using artemia salina (brine shrimp). planta medica. 1993; 59:250-252. svircev, z., cetojevic-simin, d., simeunovic, j., karaman, m. and stojanovic, d. (2008). the antibacterial, antifungal and cytotoxic activity of terrestrial cyanobacterial strains from serbia. science in china series c: life sciences. 51(10): 941-947. vaara, t., vaara, m. and niemela, s.n. (1979). two improved methods for obtaining axenic cultures of cyanobacteria. applied and environmental microbiology. 38 (5): 1011-1014. wijesekara, m.a. and manage. p.m. (2016).in vitro screening of antibacterial and antioxidant properties of freshwater cyanobacterium lyngbya sp. proceeding of the international conference on multidisciplinary approaches:09. williams, p. g., yoshida, w. y., moore, r. e. and paul, v. j. (2001). isolation and structure determination of obyanamide, a novel cytotoxic cyclic depsipeptide from the marine cyanobacterium lyngbya confervoides. journal of natural products. 65(1): 29-31. yadav. v., shinto. and bourdette, p. (2010). complementary and alternative medicine for the treatment of multiple, sclerosis natl, inst health 6: 381-395. chapter five: discussion yalew /journal of tropical forestry and environment vol. 5. no 01 (2015) 19-30 19 the perplex of deforestation in sub-saharan africa a.w. yalew * dresden leibniz graduate school, leibniz institute of ecological urban and regional development, tu dresden, germany date received: 08-10-2014 date accepted: 10-05-2015 abstract deforestation has been a complex phenomenon to study in sub-saharan africa. the average annual deforestation rate in the region is by far higher than the world average. what causes and drives deforestation in the region are debated to date. the present paper is motivated by this debate. it attempts to test whether the maintained hypotheses on the causes of deforestation can give answer to the problem in sub-saharan africa. it used average cross-national data of forty eight countries in the region. the data are retrieved from international sources. the spearman’s rank correlation coefficients between two deforestation indicators and five often-cited causes of deforestation were computed. the role of public forest ownership, share of forest and agricultural products in total exports, and the year of forest laws enacted are also discussed. however, it finds no clear, strong, and systematic pattern to argue that population density, rural population, rural poverty, industrial logging for exports, economic growth, late enactment of forest laws, and public ownership of forests are underlying causes of deforestation in the region. the trends of forestland in rwanda and zimbabwe vividly present the finding. therefore, future studies related to the topic in the region shall focus on sub-national panel data. keywords: deforestation, population, economy, institutions, sub-saharan africa 1. introduction deforestation is one of the major environmental problems in sub-saharan africa (ssa). the share of forest area in ssa has declined from 29.3% in 1990 to 26.1% in 2007 (world bank, 2010). africa has lost about 3.4 million hectares of forest each year in 2000-2010 (fao, 2010). the average annual rate of deforestation of the region (0.8%) is still by far higher than the world average (0.15%) in 1990-2010 (fao, 2010). nevertheless, africa has settled at the bottom in terms of public expenditure on forest sector per hectare (fao, 2010). in contrast of its clear trend, however, deforestation in ssa has been a very complex phenomenon to study (sieboek, 2002; rudel, 2013). what exactly causes deforestation in the region is open to debate. with poor score to halt deforestation and scientific consensus on what causes and exacerbates deforestation in the region, the success of recent forest management initiatives such as clean development mechanism (cdm) and reducing emissions from deforestation and forest degradation (redd and redd+) will be questionable because, without proper understanding of true causes, effective policies cannot be designed and implemented (pearce, * correspondence: a.yalew@dlgs.ioer.de tel: +49 35146342349 issn 2235-9370 print/issn 2235-9362 online © university of sri jayewardenepura mailto:a.yalew@dlgs.ioer.de 20 2001). among others, testing the maintained theoretical hypothesis that links different demographic, economic, and institutional factors with deforestation helps to identify and understand the root causes of deforestation in the region. this is the main motivation of this paper. for data consistency and completeness, international data sources, world bank, fao, oecd, and penn world tables were used. it uses two methods of analysis. first, each maintained hypothesis was tested against the data from ssa. however, it finds no clear, strong, and systematic correlation to argue that population density, rural population, rural poverty, industrial logging for exports, economic growth, late enactment of forest laws, and public ownership of forests as underlying causes of deforestation in ssa. second, partial rank correlation coefficients (spearman’s rho) were calculated for orderable factors. but, it only affirms the afore mentioned conclusion. the findings based on average cross-national data undermine the importance of incumbent hypothesis to explain the deforestation in ssa. at the same time, it is hardly possible to provide simple generalisation on the relative importance of some factors over the others. therefore, future studies should focus on sub-national panel data. better research funds should be available from ssa countries themselves to unpin researchers from international data. the rest of the paper is organised as follows. section 2 discusses the methodology while section 3 presents and discusses the results. the conclusions are given in section 4. 2. methodology 2.1 data and data sources the study used secondary data from international sources on forests, demographic, economic, and institutional indicators. the demographic, economic, and institutional factors considered here are based on the theoretical and empirical literature on the causes of deforestation in tropical regions (butler and laurance, 2008; titenberg, 2000; laurance, 1999), in the ssa region (rudel, 2013; mitchard and flintrop, 2013; diarrassouba and boubacar, 2009; boahene, 1998; barnes, 1990) and countries in the ssa (sieböck, 2002; rusing, 2000). table 1: description of the data and data sources. variable description measure data of data source lfa net loss of forest area as percentage of total land area % 2007 & 1990 world bank 2010 adr average annual rate of deforestation % 1990-2010 fao 2005, 2010 ysfl year of specific forests laws was enacted year country specific fao 2010 pbc share of total forest under public ownership % 2005 fao 2010 pvt share of total forest under private ownership % 2005 fao 2010 othr share of total forest under other than public & private % 2005 fao 2010 egr average annual economic growth rate (at 2005 price) % 1990-2007 heston et al. 2009 ge average government effectiveness index 1996-2012 kaufmann et al. 2013 ag/gdp average share of agriculture in gdp % 1990-2010 world bank 2013 exp share of forest and agricultural commodities in the total exports % 2008 oecd 2010 pd population density (number of people per square kilometer) % 2004 & 2008 fao 2005, 2010 pr rural population (% total population a country) % 2004 & 2008 fao 2005, 2010 prp rural poverty (% of rural poor in the total rural population of a country) % 1990-2010 (of available years) oecd 2010, world bank 2010 yalew /journal of tropical forestry and environment vol. 5. no 01 (2015) 19-30 21 the international data sources were preferred for comprehensiveness of factors and consistency of the data. data is averaged overtime to compensate the missed as well as lagged effects of the factors. table 2 below summarises the data. table 2: summary of data. forests demographic economic institutional country lfa adr pd pr prp ag/gdp egr exp ge pbc pvt othr ysfl angola 1.97 0.2 12.6 53 94 9.63 3.8 0 -1 100 0 0 1955 benin 9.95 1.1 70.2 57 33 33.7 1.1 38 -0 99 1 0 1993 botswana 3.55 1 3.03 44 na 3.48 2.9 0 0.6 24 5 71 1968 burkina faso 1.49 1 50.6 81 52 35.2 2 63 -1 100 0 0 1997 burundi 6.05 2.2 300 90 37 45.3 -2 53 -1 100 0 0 1985 cameroon 7.91 1 37.6 45 50 22.8 -1 15 -1 100 0 0 1994 cape verde -6.6 -1.4 122 42 55 10.9 5 0 -0 100 0 0 na central african rep 0.81 0.1 6.67 59 na 52.1 -1 46 -2 91 0 9 2008 chad 1.07 0.7 8.01 74 67 31.5 3.8 95 -1 100 0 0 2008 comoros 4.08 7.5 366 68 na 44.3 -1 63 -1 100 0 0 na congo 0.85 0.1 11.2 43 58 7.58 -0 0 -1 100 0 0 2000 cote d'ivorie -0.7 -0.1 59.5 53 na 25.8 -1 29 -1 99 1 0 1965 djibouti 0 0 33.9 15 49 3.49 0.4 24 -1 100 0 0 na dr congo 3.33 0.2 26.1 67 76 48.2 -6 0 -2 100 0 0 2002 equatorial guinea 9.22 0.7 20.5 56 na 28.2 23 0 -1 100 0 0 1997 eritrea 0.57 0.3 46.7 79 na 20 0.7 8 -1 na na na 2006 ethiopia 1.97 1.1 72 84 45 52.1 1.6 54 -1 100 0 0 na gabon 0.67 0 5.67 15 45 6.8 -1 1 -1 100 0 0 2001 gambia -3.3 -0.4 155 59 63 22.7 0.4 49 -1 94 6 0 1998 ghana 9.5 2.1 97.8 52 39 39 1.8 43 -0 100 0 0 1998 guinea 3.08 0.5 36.4 65 na 22.1 0.7 0 -1 99 1 0 1989 guinea-bissau 5.84 0.5 55.3 68 na 56 0.9 93 -1 100 0 0 1991 kenya 0.37 0.3 62.5 69 49 29.3 0.3 22 -1 39 61 0 2005 lesotho -0.1 -0.5 63.8 79 na 13.9 2.5 54 -0 14 0 86 1998 liberia 10.6 0.7 37.4 46 na 67.8 -2 13 -2 100 0 0 1973 madagascar 1.6 0.4 31.4 72 74 28.4 -1 17 -0 98 2 0 1997 malawi 5.95 0.9 138 82 47 35.6 1.1 67 -1 na na na 1997 mali 1.39 0.6 9.89 68 76 42.2 2 77 -1 100 0 0 1995 mauritania 0.16 3.3 2.92 48 61 32 0.9 0 -0 97 3 0 2007 mauritius 1.18 0.3 620 57 na 7.76 3.8 29 0.6 48 52 0 1983 mozambique 1.08 0.5 26.2 63 55 30.6 3.4 0 0.5 100 0 0 1999 namibia 1.52 0.9 2.74 65 na 10.6 1.4 0 0.1 na na na 2001 niger 0.56 1.9 10.8 81 66 39.4 -0 0 -1 100 0 0 2002 nigeria 7.65 3.3 160 52 na 37.2 3.1 0 -1 100 0 0 na rwanda -8.8 -1.9 367 81 63 38.1 2.8 30 -1 79 21 0 1988 sao tome and principe 0 0 167 51 na 18.6 0.2 68 -1 na na na na senegal 3.97 0.5 58.7 54 na 18.1 0.9 0 -0 100 0 0 1998 seychelles 0 0 186 47 na 3.33 2.7 0 0 77 23 0 1955 sierra leone 4.59 0.9 77 61 79 50.9 -2 0 -1 14 86 0 1988 somalia 2.08 1 14.9 64 na na -2 26 -2 na na na na south africa 0 0 39.3 41 na 3.6 1.6 0 0.7 60 40 0 1998 sudan 4.21 0.3 15.7 59 na 37.4 3.6 0 -1 91 9 0 2002 swaziland -4.6 -0.9 66.6 76 75 10.6 1.5 35 -1 78 22 0 2001 tanzania 7.91 1.1 44.7 69 39 37.6 2.1 12 -0 100 0 0 2002 togo 6.23 4.6 105 61 na 36.8 -1 56 -1 27 73 0 2008 uganda 7.46 2.4 146 86 42 36.2 3.4 39 -0 32 68 0 2003 zambia 10.2 0.3 15.6 64 74 21.5 2.5 0 -1 100 0 0 1973 zimbabwe 13.8 1.8 33 64 48 17.8 -2 12 -1 63 37 0 1949 ssa average 2.92 0.84 85.4 61 58 28.2 1.3 26 -1 84 12 4 source: author compilation based on sources given in table 1. na: data not indicated in these data sources. zero values in column 9 do imply the forest and agricultural (raw or processed) items are not reported in the first three main export items of that country. 22 2.2 research method the overall method of analysis is comparing and contrasting the relative position of a country (or a group of countries) in terms of deforestation and in terms of sources of deforestation which are demographic, economic, and institutional variables. in that way, if a country (or a group of countries) is placed in close positions in terms of deforestation and hypothesised cause of deforestation, then that specific hypothesis holds true in ssa. in other words, the nearer is the distance between the ranks, the more is that demographic, economic or institutional factor is responsible for deforestation in the region. first, each hypothesis linking a demographic, economic, or institutional factor with deforestation is compared with the empirical data in ssa. such discussion helps to see the role of factors where ranking makes less sense. for example, all forests are under public ownership right in half of the countries. in addition, for some factors like rural poverty, data is available for only 28 countries. then, partial rank correlation coefficients between the two deforestation indicators and five often-cited drivers of deforestation are computed. partial rank correlation coefficients (spearman’s rho, ρ) measure the dependence between two orderable variables. for a sample size of n, rank correlation coefficient is computed as in equation 1: ∑ ( ) ( ) where: di = the difference between the ranks of the dependent variable and the independent variable the dependent variable is either of the two deforestation indicators. the independent variable is any of the five socio-economic factors. for deforestation, countries are ranked from highest to lowest value. the rank of countries for the socio-economic factors is from the expected association with the rank of deforestation. for instance, government effectiveness was ranked from worse (negative) to better (positive) as deforestation is expected to be higher in countries with ineffective governments. the ranks are given in table 3 in the following section. 3. results and discussion 3.1 maintained hypotheses versus empirical data in ssa population and deforestation population and its growth have been argued long to cause deforestation in developing countries (laurance, 1999; pearce, 2001). increase in population increases demand for agricultural products and hence agricultural land. the search for extra agricultural land induces forest clearance. if the population growth specially happens in rural areas, it increases the fuelwood demand which still threatens forest (barnes, 1990). in addition, as population increases the demand for industrial wood products will increase which in turn escalates the industrial logging. hence, the fact that population and its growth puts pressure on the environment is indisputable. nevertheless, linking population and its growth directly with deforestation is oversimplification (sieböck, 2002). therefore, population density may better metrics (sieböck, 2002). therefore, average population density (number of peoples per square kilometer) was used as proxy to population pressure on forestlands. yalew /journal of tropical forestry and environment vol. 5. no 01 (2015) 19-30 23 only mauritius (620), rwanda (367), comoros (366), and burundi (300) have population density greater than 200 km -2 . among the four, burundi lost 6% forest area (% total land) in the period of 1990-2007. while the average annual deforestation rate (1990-2010) is 2.2% well above the world and ssa average rate of deforestation in the two decades. the net loss of forest area in comoros is 4.08% (1990-2007) but with highest annual rate of deforestation 7.5% (1990-2010). linking population density and deforestation is also cogent enough to explain the deforestation (in terms of both indicators) in uganda, nigeria, malawi, and togo which all have population density between 100 and 200, and rate of deforestation above the ssa’s average. in contrast, this maintained hypothesis cannot explain for the case of rwanda, seychelles, sao tome and principe, gambia, and cape verde which still do have population density above 100 km -2 but gained net area of forest in terms of both indicators in the period. alternatively, we can test the hypothesis if there is no or little deforestation in countries with low population density. the average annual deforestation rate in mauritania, a country with the lowest population density (3 km -2 ), is 2.7%. the population density in zimbabwe, which lost about 13% forest area and annual deforestation rate 1.8%, is 39 km -2 . likewise, equatorial guinea, cameroon, niger, liberia, and benin do have population density below ssa’s average (which is 85 km -2 ). whereas the deforestation rates in this countries are above the ssa average in both indicators of deforestation. in sum, the empirical data supports little to generalise that population density is a main force behind deforestation in ssa. rural poverty and deforestation natural resources represent important part of the asset base of the poor (pearce, 2001). many poor families find many forest products (timber, herbal medicines, fruits, and firewood) in the basket of their basic necessities (diarrassouba and buobacar, 2009). thus, poor always tend to place higher discount rate on environment (nayak, 2004). nor rural poor invest in land development (sieböck, 2002). rural peasants will see forestland as an opportunity to become landowner (tietenberg, 2000). therefore, some tend to conclude that poverty is the primary cause of deforestation in the tropics (diarrassouba and buobacar, 2009). rural population (% national population) and rural poverty were taken as a proxy to rural society. we consider each in turn. the average rural population in ssa is 61% of the total population. the two countries with lowest rural population are djibouti (14.5%) and gabon (15.3%). coincidentally the deforestation (in terms of both indicators) in both countries is negligible. of the 26 nations with proportion of rural population higher than ssa’s average, only 12 of them have experienced average annual rate of deforestation higher than the ssa’s average. in contrast, in 14 countries that loss of 5% and higher, only 5 have rural population which is higher than the ssa’s average. cameroon, liberia, ghana, nigeria, and benin have low percentage of rural population but higher deforestation rate (in both measures) compared to rwanda, lesotho, and swaziland which have higher rural population percentage. countries placed at bottom in terms of rural population (<40%) uganda, ghana, tanzania, burundi, and benin assumes the reverse rank in terms of deforestation. rural poverty data was available only for 28 countries. even though about 60% rural population lived under poverty, rwanda and swaziland still gained forest areas. republic of congo and cape verde have rural poverty ratio higher than zimbabwe, malawi, and ethiopia but scored better when it comes to deforestation. 24 taken together, the analysis based on average data offers no systematic relationship between rural population and rural poor and deforestation in ssa. being poor and rural dweller is not a sufficient reason to be blamed for deforestation. this goes with angelsen et al. (1999) (cited in sieböck, 2002) which finds that there is little empirical evidence to support that poverty is the underlying cause of deforestation. nayak (2004) also finds no clear pattern between poverty and environmental degradation in rural india. opposite to this, there are even some experiences in which rural and poor community has used forests and other natural resources in very sustainable manner (sieböck, 2002). especially if forest (other natural resources) management power is devolved to the local community, forests can successfully be used in poverty reduction beyond controlling deforestation (shyamsundar et al., 2005). agriculture and deforestation shifting cultivation for subsistence agriculture, cash crops cultivation, and overgrazing involve clearing forests. one way to look at the linkage between agriculture and deforestation is through what happens to forests in countries which heavily depends on agricultural products, i.e., livestock, sesame, coffee, cocoa, cotton, cashew nuts, tea, fruits, flower cuts, tobacco, and sugar cane exports. as to 2008, agricultural commodities are among the three main export items in 21 ssa countries (oecd, 2010). of these countries, only 10 exhibit average deforestation rate higher than the ssa average. this leaves us with no strong evidence in defense of tradable cash crop cultivation is underlying cause of deforestation in ssa. another way to test the linkage is through the share of agriculture in gross domestic product (gdp) and deforestation 1 . agriculture accounts more than 30% of gdp in 13 of the 18 ssa nations with higher average rate of deforestation. in 10, out of 14 countries with high forest area lost, agriculture contributes more than 30%. excepting botswana, in all countries where agriculture contribution less than 10% of gdp, deforestation is meager. another exception is the situation in zimbabwe and rwanda where, respectively, agriculture contributes 17% and 38% of gdp. this contrasts the 13% loss and 8.7% gain, respectively in zimbabwe and rwanda. keeping these exceptions, the view that agricultural encroachment causes or triggers deforestation loosely explains the situation in ssa. industrial logging and deforestation industrial logging without tree replacement depletes forest (butler and laurance, 2008; tietenberg, 2000; laurance, 1999). commercial logging also opens up previously inaccessible forests for new settlers which exacerbates deforestation. in addition, industrial forest products are seen as means of generating foreign exchange earnings for debt repayment in low-country income countries (tietenberg, 2000). this premise holds true for ssa where industrial logging is primary for export. thus, we can intertwine the two views together. the view whether industrial logging leads to deforestation in ssa can be captured by the deforestation in countries where forest products constitute the three main export items. forest products (lumber, tropical hardwoods and natural rubber latex) are among the three main export items in cameroon (8.1% of total exports), liberia (12.8% of total exports) central africa republic (45.5% of total exports), and chad (94% of total exports). the deforestation 1 agriculture, value added (% of gdp) here corresponds to isic divisions 1-5 and it includes forestry, hunting, and fishing, as well as cultivation of crops and livestock production. value added is the net output of a sector after adding up all outputs and subtracting intermediate inputs. it is calculated without making deductions for depreciation of fabricated assets or depletion and degradation of natural resources (world bank, 2013). yalew /journal of tropical forestry and environment vol. 5. no 01 (2015) 19-30 25 data, however, shows the reverse. thus, linking industrial logging and the share of forest products export directly, therefore, may be oversimplification as the discussion here does not substantiate the industrial logging-deforestation nexus in titenberg (2000) and laurance (1998). however, it goes in line with (sieböck, 2002) which pointed “there are several examples for commercial logging operators carrying out sustainable forest management in the tropics such as precious woods in costa rica and the amazon or compagnie équatoriale des bois (ceb) thanry in gabon”. economic growth and deforestation economic growth imposes detrimental effects on forests especially in countries where forest and agricultural products take the largest share in total exports and real gdp. in other words, if high economic growth rate is recorded in countries with high rate of deforestation (or net loss of forest area), then the share of agriculture in gdp and/or agricultural and forest products in total exports in the same countries is expected to be high 2 . agriculture contributes more than 50% of the gdp in liberia, guinea-bissau, central republic africa, ethiopia, and sierra leone. while forest products constitute among the three main export items in liberia and central republic africa, agricultural products are among the three main exports in ethiopia, guinea-bissau, and liberia. therefore, economic growth, if it happens, in liberia, central republic africa, ethiopia, and guinea-bissau would trigger deforestation either due direct export purpose and/or due to land encroached for agricultural purpose. liberia is highly deforested in both indicators but with only -2% average rate of real gdp growth. guinea-bissau has lost about 6% of its forest area (% of total land area), but scored only 0.9% average rate of real gdp growth. alternatively, we can see whether countries with high deforestation rate (and at the same time high gdp growth rate) are dependent on agriculture and forests for livelihood and export. equatorial guinea scored an average of 23% real gdp growth rate and lost 9% of its forest area (% total land area). however, neither agricultural nor forest items are mentioned in the three main export items in equatorial-guinea. on the reverse, forest products constitute 94% of the total export in chad and ranked fourth in terms of real gdp growth rate (3.77%). but, the deforestation rate in chad is modest. this leaves us with little evidence to conclude that economic growth causes or exacerbates deforestation in agriculture and forest dependent nations in ssa. weak institutions and deforestation very recent studies in the environment-society nexus place more on emphasis on the role of institutions and governance. accordingly, lack of good governance drives of deforestation rather than industrial logging, rural poverty, and agricultural encroachment per se (sieböck, 2002). this lack of governance in forest management is manifested through lack of government commitment, corrupted and rent-seeking bureaucrats and bureaucracy, weak monitoring and law enforcement, political instability, and highly centralised power structures. three indicators of institutional aspects were considered here. these are government effectiveness (ge) indicator, the years of forest laws enacted, and public ownership of forest in different countries of the region. 2 the economic growth rate after 2007 is excluded in order to control the effect of global financial and economic crisis especially on oil and mineral exporting nations so that will not affect the ranking and, the economic growth rates refer to real gdp growth rates measured at 2005 price (heston et al., 2009). 26 ge is one of the six major worldwide governance indicators calculated and updated since 1996 by kaufmann and others. 3 ge reflects “perceptions of the quality of public services, the quality of the civil service and the degree of its independence from political pressures, the quality of policy formulation and implementation, and the credibility of the government's commitment to such policies” (kaufmann et al., 2013). the value of ge ranges between -2.5 (weak) and 2.5 (strong). somalia (-2.05) scores the most ineffective government and south africa (0.66) the better one. however, deforestation in somalia is far less than deforestation in ghana, benin, tanzania, and uganda where the average ge indicates good governance even by the ssa standard. early year of specific forest law enactment indicates early acknowledgment of the problem. then, it is natural to presume that efforts to have been placed to arrest the problem since the specific forest laws are introduced in the country. zimbabwe (in 1949), liberia (in 1976), burundi (in 1985) (1993), cameroon (1994) are among the pioneers to enact specific of forest laws but unable to halt deforestation in 1990-2010. out of 15 nations that enacted in 2000-2008, only four, togo, mauritania, uganda, tanzania and niger reported high deforestation rate. in sum, it can be concluded that neither higher government effectiveness nor earlier implementation of forest laws have saved forests in ssa. private property right regime leads efficient and sustainable use of natural resources (tietenberg, 2000). in other words, public ownership and management of natural resources (or forests in our case) may be sources of deforestation. government failure for sustainable forest management can easily be captured if deforestation is high in countries with high percentage of public ownership and management of forests. deforestation in togo (73% non-public) and uganda (86% non-public) is as high as the deforestation in nigeria, ghana or liberia where all forests are owned by the public. deforestation in south africa, seychelles, swaziland and rwanda where 80% and 60% are public is almost negligible. though public ownership is zimbabwe than in rwanda and swaziland, deforestation in the former is by far higher than the latter. therefore, we see that neither private nor public ownership per se can be blamed for deforestation. in closing, the qualitative discussion does support little the maintained hypotheses on the causes and drivers of deforestation in developing countries. the following section goes further to check the validity of the discussion in this section by computing partial correlation coefficients between the two deforestation indicators and five orderable factors. 3 the six dimensions include: voice and accountability, political stability and absence of violence/terrorism, government effectiveness, regulatory quality, rule of law and control of corruption. all the available data (1996-2012) is used to compensate for the years in 1990-1995. yalew /journal of tropical forestry and environment vol. 5. no 01 (2015) 19-30 27 table 3: rank of countries. country lfa adr egr ag/gdp pd ge pr zimbabwe 1 9 47 35 31 16 23 liberia 2 21 45 1 28 3 41 zambia 3 30 14 31 37 22 21 benin 4 10 23 20 16 38 31 ghana 5 7 18 11 13 42 37 equatorial guinea 6 20 1 26 35 6 32 tanzania 7 11 15 13 25 37 13 cameroon 8 14 36 28 27 26 42 nigeria 9 3 9 15 7 18 36 uganda 10 5 7 17 9 36 2 togo 11 2 40 16 12 5 26 burundi 12 6 43 7 4 7 1 malawi 13 17 24 18 10 28 4 guinea-bissau 14 27 26 2 22 10 16 sierra leone 15 19 44 5 14 9 25 sudan 16 31 6 14 36 13 29 comoros 17 1 42 8 3 8 15 senegal 18 26 27 34 21 41 33 botswana 19 16 10 46 46 47 43 dr of the congo 20 35 47 6 34 2 18 guinea 21 25 29 30 29 19 19 somalia 22 13 46 … 38 1 22 ethiopia 23 12 20 4 15 20 3 angola 24 34 3 40 39 12 34 madagascar 25 28 38 25 32 34 12 namibia 26 18 22 39 48 45 20 burkina faso 27 15 17 19 23 31 5 mali 28 23 16 9 42 27 17 mauritius 29 33 5 41 1 46 30 mozambique 30 24 8 23 33 35 24 chad 31 22 4 22 43 15 11 congo 32 37 34 42 40 11 44 central african republic 33 36 39 3 44 4 27 gabon 34 39 37 43 45 29 47 eritrea 35 32 28 32 24 17 8 niger 36 8 35 10 41 23 7 kenya 37 29 32 24 19 32 14 mauritania 38 4 25 21 47 40 39 djibouti 39 38 31 45 30 24 48 são tomé and príncipe 40 40 33 33 6 30 38 seychelles 41 41 12 47 5 44 40 south africa 42 42 19 44 26 48 46 lesotho 43 45 13 36 18 39 9 côte d'ivoire 44 43 41 27 20 14 35 gambia 45 44 30 29 8 33 28 swaziland 46 46 21 38 17 21 10 cape verde 47 47 2 37 11 43 45 rwanda 48 48 11 12 2 25 6 source: based on table 1. 28 3.2 evidence from rank-correlation coefficients table 4 below summarises the partial rank correlation coefficient. it affirms the conclusion from the previous discussion. that is rank based on average data provides no/little ground to support weak institutions, high proportion of rural population, higher economic growth, and high population density cause deforestation in ssa. it is only the share of agriculture in gdp which loosely supports the established view. table 4: summary of partial rank correlation coefficients. ρ ar ρ a1 ρ a2 ρ a3 ρ a4 ρ a5 0.7084 -0.0200 0.0695 0.4188 -0.0996 0.2828 ρ ra ρ r1 ρ r2 ρ r3 ρ r4 ρ r5 0.7084 -0.0200 0.2408 0.4931 -0.1420 0.1324 source: based on the table 3 ρ=spearman’s rho, a=net forest area lost, r=average annual deforestation rate, 1=average population density, 2=average percentage of rural population, 3=average share of agriculture in gdp, 4=average economic growth rate, and 5=average government effectiveness. 3. conclusion average empirical data from ssa was used to test the maintained hypotheses on drivers of deforestation in developing countries. however, this paper finds no strong, clear and systematic pattern to defend that population density, rural population and poverty, industrial logging, forest product export, economic growth and lack or late enactment of forest laws causes deforestation in ssa. considering rwanda and zimbabwe makes the findings more vivid. looking at the hypotheses on causes of deforestation (population density, rural poverty, percentage of rural population, agricultural share in gdp, and enactment of forest laws), one may contemplate that deforestation in rwanda to be alarming than in zimbabwe whereas the deforestation statistics confirms the opposite. between 1990 and 2007, the forest area as percentage of total land area increased by 8% in rwanda while it decreases by in zimbabwe 13%. the annual average rate of deforestation (1990-2010), respectively, was -1.9% in rwanda and 1.8% in zimbabwe. this contradicts laurance (1999) which generalised that population pressure, weak government institutions and poor policies and industrial logging for export is the four key drivers of deforestation in tropical regions in which africa was its sample. the results also challenge sieböck (2002) which strongly concluded that deforestation in ssa is mainly due to governance problems. high deforestation rate is reported in countries with better government effectiveness in the region like botswana, ghana, and benin. nor it agree with rudel (2013) which associated lower deforestation in wetter congo basin with the transition to minerals and oils revenues coupled with declines in agriculture and increased imports of cereals from abroad because countries with high share of oil and mineral exports in their total exports (i.e., nigeria, zambia, zimbabwe of benin, liberia, equatorial-guinea and ghana) have also scored high rate of deforestation. better information would have been gleaned from sub-national panel data on the loss of different forests overtime in different countries. such data, however, is hardly available in ssa countries. therefore, it requires ssa countries themselves to avail better research funds to detach researchers from international data and incumbent hypotheses based on studies in other developing regions like latin america and south asia. in addition, governments shall look beyond merely enacting specific forest laws. law enforcements should be improved. otherwise, the success of recent forest management initiatives such as cdm and redd+ in the region will be under question. yalew /journal of tropical forestry and environment vol. 5. no 01 (2015) 19-30 29 references arcand, j., guillaumont, p. and sylviane, g.j. 2008. deforestation and the real exchange rate. journal of development economics, 86(2): 242-262. barbier, e.b. and burgess j.c. 2001. the economics of tropical deforestation. journal of economic survey, 5(3): 412-433. barnes, d.f. 1990. population growth, wood fuels, and resource problems in sub-saharan africa. energy series paper no. 26. industry and energy department working paper. world bank. boahene, k. 1998. the challenge of deforestation in tropical africa: reflections on its principal causes, consequences and solutions. land degradation and development, 9: 247-258. butler, r.a. and laurance, w.f. 2008. new strategies for conserving tropical forests. trends in ecology and evolution, 23(9): 469-472. culas, r.j. 2007. deforestation and the environmental kuznets curve: an institutional perspective. ecological economics, 61(2-3): 429-437. de sherbinin, a., lopez-carr, d., cassels, s., jiang, l., lopez-carr, a. and miller, k. 2014. population-environment theory and contemporary applications. encyclopaedia of earth. web. http://www.eoearth.org/view/article/5378ed20cf2aafa2ccd987e. [accessed 10 september 2014] deacon, r.t. 1999. deforestation and ownership: evidence from historical accounts and contemporary data. land economics, 75(3): 341-359. diarrassouba, m. and boubacar, i. 2009. deforestation in sub-saharan africa. selected paper for presentation at the southern agricultural economics association annual meeting, atlanta, georgia, january 31, february 3. food and agriculture organization of the united nations (fao). 2005. global forest resources assessment 2005. fao forestry paper 147. rome. food and agriculture organization of the united nations (fao). 2010. global forest resources assessment 2010. fao forestry paper 163. rome. heston, a., summers, r., and aten, b. 2009. pwt6.3. center for international comparisons of production, income and prices at the university of pennsylvania. web. https://pwt.sas.upenn.edu/php_site/pwt_index.php. [accessed 24 december 2013]. kaufmann, d., kraay, a. and mastruzz, m. 2013. the worldwide governance indicators: 2013 update. website. www.govindicators.org. [accessed 21 june 2014]. matthews, e., payne, r., rohweder, m. and murray, s. 2000. pilot analysis of global ecosystems: forest ecosystems. world resources institute. washington, dc. mitchard, e.t. and flintrop, c.m. 2013. woody encroachment and forest degradation in sub-saharan africa's woodlands and savannas 1982-2006. phil.trans.r.soc.b.2013 368. motel, p. 2010. causes of deforestation. encyclopaedia of earth. web. http://www.eoearthorg/view/article/150961. [accessed 1 september 2014]. naoto, j. 2006. international trade and terrestrial open-access renewable resources in a small open economy. canadian journal of economics, 39(3): 790-808. nayak, p. 2004. poverty and environmental degradation in rural india: a nexus. neea annual conference. january, dibrugarh, assam, india. organization for economic cooperation and development (oecd). 2010. african economic outlook 2010. paris, france. pearce, d.w. 2001. the economic values of forest ecosystems. ecosystem health. 7(4): 284-296. ramon, l. and galinato, g. 2005. trade policies, economic growth, and the direct causes of deforestation. land economics, 81(22): 145-169. http://www.eoearth.org/view/article/5378ed20cf2aafa2ccd987e https://pwt.sas.upenn.edu/php_site/pwt_index.php http://www.govindicators.org/ http://www.eoearthorg/view/article/150961 30 reusing, m. 2000. change detection of natural high forests in ethiopia using remote sensing and gis techniques. international archives of photogrammetry and remote sensing. xxxiii: b7. rudel, t.k. 2013. the national determinants of deforestation in sub-saharan africa. phil.trans.r.soc. b 2013 368. shashi, k. and berry, a.r. (eds.). 2005. institutions, sustainability, and natural resources: institutions for sustainable forest management. springer, netherlands. shyamsundar, p., araral, e. and weeraratne, s. 2005. devolution of resource rights, poverty and natural resource management: a review. environmental economics series. paper no. 104. world bank publisher, washington dc. sieböck, g. 2002. a political, legal and economic framework for sustainable forest management in cameroon. concerted initiatives to save the rainforests. master thesis (unpublished). lund university, sweden. tietenberg, t. 2000. environmental and natural resource economics. (5 th ed). addison wesley longman, new york. world bank. 2010. millennium development goals. world bank publishers, washington dc. world bank. 2013. world bank data base: agriculture and rural development. http://data.worldbank.org/topic/agriculture-and-rural-development. [accessed 13 july 2014]. http://data.worldbank.org/topic/agriculture-and-rural-development 10 bioactivity and volatile profiling of azadirachta indica leaves for the management of maize weevil, sitophilus zeamais (motsch.) infestations a.g.w.u. perera*1, m.m.s.c. karunaratne1 and s.d.m. chinthaka2 1 department of zoology, university of sri jayewardenepura, nugegoda, sri lanka 2 department of chemistry, university of sri jayewardenepura, nugegoda, sri lanka date received: 2018-04-26 date accepted: 2018-05-08 abstract neem (azadirachta indica a. juss), is known to possess a wide range of pharmacological properties and is thus commercially exploitable. apart from its medicinal potential, a considerable progress has been achieved regarding biological potential and chemical composition of the leaves which is an ever-increasing interest to the scientific community. during this study, biological phenomena and secondary metabolite composition of a. indica leaves were examined in the management of sitophilus zeamais on stored maize. insecticidal and repellent potential of a. indica leaf powders were evaluated in both contact and fumigant forms. phytochemical screening of 11 phyto constituents was performed following the standard procedures for n-hexane, dichloromethane, ethyl acetate, methanol and aqueous leaf extracts. volatile profile of a. indica leaves was characterized by employing headspace-solid-phase micro extraction coupled with gas chromatography-mass spectrometry (hs-spme/gc-ms). over 60% weevil repellency was recorded at doses above 23.33%, whereas 100% and 67% contact and fumigation mortalities were observed respectively, 9 days after treatment at the dose of 33.33% and the respected ld50 values were 1.56 g and 4.48 g. thirty two volatile compounds were identified in three distinct chemical classes (monoterpenoid, sesquiterpenoid and purine nucleosides). γ-elemene (24.06%), 3,7 (11)-eudesmadiene (6.83%), caryophyllene (6.40%), and 10s,11s-himachala-3(12),4-diene (6.36%) were the major constituents of neem leaf volatiles, followed by other compounds present in less than 4% which might be responsible for varied biological activities observed. thus the odour impact of the bioassayguided study clearly implies that a. indica leaves can be harnessed against s. zeamais infestations. keywords: azadirachta indica, sitophilus zeamais, headspace-solid-phase micro-extraction, insecticidal activity, repellency 1. introduction maize (zea mays) is a versatile crop among the three most important cereal crops of the world, the other two being wheat and rice. it possesses a prominent genetic diversity and is grown over a range of agro climatic zone (ministry of environment, forests & climate change, government of india and department of biotechnology, 2011). in sri lanka, the maize cultivation has become a highly commercialized venture during the last several years (department of agriculture, 2013). though, the factors restricting the maize production are also diverse, the most threatening being the insect attack during the storage (ortega, 1987). more recently, in every respect of the world, attention of the researchers has been paid towards the exploitation of plant products as stored grain protectants against insect pests due to the increasing public concern over the level of insecticidal residues in food (dubey et al., 2008). * correspondence: wathsalauda@gmail.com issn 2235-9370 print/issn 2235-9362 online © university of sri jayewardenepura daham doi: 10.31357/jtfe.v8i1.3479 perera et al. /journal of tropical forestry and environment vol. 8, no. 01 (2018)/ 10-24 11 ipm programs have demonstrated that current levels of insecticidal use in many circumstances are not necessary and, frequently, are even counter-productive (khater, 2012). many farmers in sri lanka may not be able to afford synthetic insecticides and even when those are affordable to growers through government subsidies, limited literacy and lack of protective equipment make way to thousands of accidental poisonings annually (isman, 2006). the plant kingdom offers a rich source for a wide array of structural biodiversity of natural secondary metabolites (el-wakeil, 2013). insect-plant interactions have been studied for many years, but an extraordinarily discerning account on these complex co-adaptive relationships could provide a basis for using plant derived chemicals in green approaches for a better management of insect pests inhabiting stored grains (coats et al., 1991). they can play a huge role in developing countries like ours as a new class of eco-friendly and biodegradable products for controlling pests. also, they offer unique and challenging opportunities for exploration, development and commercialization of their own botanicals. there is a wide scope for the use of plant-based insecticides in the integrated management of stored insect pests because botanicals may help in preventing the dumping of tons of insecticides on earth (khater, 2012; adeyemi and mohammed, 2014). moreover, the advances in chemical and biological technologies combined with increasing need and environmental pressure, greatly increase the interest in the development of plant products as green insecticides (khater, 2012). one such phenomenal source of green insecticide is the neem tree (azadirachta indica a. juss; meliaceae). the components taken from this evergreen tree (leaves, seeds and bark) have demonstrated an unusual biological effectiveness against a wide spectrum of insect pests (zeringue and bhatnagar, 1994). although many reviews have been published on the biological activity of other neem components, chemical basis underlying the bioactivity of neem leaves has not received much attention in the suppression of insect pest infestations. as a step in the path towards the exploration and continuation of the studies on neem tree components, the impetus of this research was to assess the insecticidal activity of neem leaves against the maize weevil (sitophiuls zeamais, motsch) which is a serious cosmopolitan field-to-store insect pest of maize and other cereal grains in tropical and subtropical regions of the world. in order to obtain a more realistic picture of the entire range of volatile organic compounds emitted by neem leaves which detected by maize weevils that responded to leaf organic volatiles, headspace solid-phase microextraction (hsspme) technique was also employed in the present study. 2. materials and methods a series of experimental designs were conducted at the agricultural insect pest management laboratory of department of zoology, faculty of applied sciences, university of sri jayewardenepura, sri lanka from january to july 2016. the relative humidity and ambient temperature during the experimental period were 84±2% rh and 29±2o c respectively. all the assessments carried out in this study were replicated five times. 2.1 collection of plant material fresh, mature and healthy leaves of azadirachta indica were collected from gangodawila area. these were ground into a fine powder using a domestic electric grinder (multinational®, 2101, india) and were packed in glass containers with tight lids and stored in a refrigerator at 4o c prior to use in the bioassays. 12 2.2 maintenance of sitophilus zeamais cultures sitophilus zeamais used for the study were obtained from infested stock of maize in the local market and then reared on un-infested maize grains in glass jars covered with muslin cloth held in place with rubber bands for the passage of air and prevention of the weevil escape. unsexed adult weevils of 37 days old were used for all experiments. 2.3 sample preparation for phytochemical screening the coarse powders were subjected to successive extraction in various solvents such as water, nhexane, ethyl acetate, methanol and dichloromethane using soxhlet apparatus. the collected extracts were then taken up for further investigations. 2.4 contact repellent effect the freshly powdered plant leaves were admixed with clean and un-infested maize grains at 5 doses (3.33%, 10%, 16.67%, 23.33%, and 33.33% w/w) per thirty grams (30 g) in separate small plastic cups (height 8 cm, diameter 7.5 cm). one week old, 20 adult weevils were introduced into each cup. the top ¼ height of the small plastic cup was perforated using a soldering gun (220v/240v, 40w, china). these holes were made to allow the weevils to escape from the plastic cup if they are repelled by the plant powders. this small plastic cup was placed inside a large plastic bottle (height 15 cm, diameter 7.5 cm) to trap the weevils moving out through the holes. before the onset of each experiment, the holes were covered with a sticky tape for 10 minutes to let the introduced maize weevils settle down inside the plastic cup. the bio apparatus was then covered with muslin cloth held in place with rubber bands to allow ventilation of weevils. the same bio apparatus filled only with 30g of rice without leaf powder was considered as the control. the number of repelled insects in the large plastic bottle was counted 1 hour after their introduction to estimate maize weevil repellency. 2.5 fumigation repellent effect the bio apparatus used was somewhat similar to the setup in the contact repellency bioassay but with some alterations. the bottom of the small plastic cup was removed and replaced by a nylon cloth which was then fitted with a small plastic container (height 4 cm, diameter 5 cm) to place the leaf powders inside the latter. this adjustment allowed the vapor of leaf powders inside the container to pass through the cloth and reach the weevils. leaf powder was then put in the plastic container at the 5 rates of 3.33%, 10%, 16.67%, 23.33%, and 33.33% w/w, and 30 g of maize grains were placed in the small plastic cups. one week old, 20 adult weevils were introduced into the small plastic cups. grains in the control test contained no leaf powders. number of repelled weevils in the large plastic bottle was counted one hour after introduction. 2.6 contact toxic effect contact toxicity was assayed by admixing 30 g of uninfested maize grains with powdered leaves of plants at the doses of 3.33%, 10%, 16.67%, 23.33%, and 33.33% w/w in the plastic containers (height 8 cm, diameter 7.5 cm). one week old, 20 adult weevils were introduced into each cup. the containers were covered with muslin cloth held firmly with rubber bands to prevent the escape of the weevils and to ensure adequate aeration. maize grains with no plant powders were included to serve as the control. the contact mortality of the weevils was recorded at 24 hour intervals up to 10 days of weevil exposure. 2.7 fumigation toxic effect the bio apparatus for the fumigation toxicity test was consisted of a small plastic container (height 4 cm, diameter 5cm) attached to a plastic cup (height 8 cm, diameter 7.5 cm). the bottom of the plastic perera et al. /journal of tropical forestry and environment vol. 8, no. 01 (2018)/ 10-24 13 cup was removed and replaced by a nylon cloth to allow the vapor of plant powders in the container to pass through the cloth and reach the weevils. leaf powders were put in the separate plastic containers at the doses of 3.33%, 10%, 16.67%, 23.33%, and 33.33% w/w while 30 g of clean and uninfested maize grains were placed in the plastic cups. one week old, 20 adult weevils were introduced into each plastic cup. the bio apparatus was covered with muslin cloth held in place with rubber bands. bio apparatus without the leaf powders was kept as the positive control. fumigant mortality of the maize weevils was evaluated daily for 10 days of weevil exposure. 2.8 preliminary qualitative phytochemical screening the crude n-hexane, dichloromethane, ethyl acetate, methanol and aqueous leaf extracts were subjected to phytochemical screening following the standard methods as described by harborne (1998) and hsu et al. (1981). 2.9 isolation of volatile organic compounds (vocs) spme fibers spme holder and fiber assemblies for manual sampling were provided from agillent technologies (palo alto, ca) and used without modification. the fiber coatings assayed were as follows: polydimethylsiloxane (pdms 30 µm), polyacrylate (pa 85 µm) (table 1). before measurements, the fiber was conditioned in the injector for 30 minutes at 250o c with split vent open to fully remove any contaminant that might cause high baseline noise and large ghost peaks. then the fiber was repeatedly injected into the gc until interfering peaks disappeared. during this desorption process the gc column oven temperature was maintained at 250o c. table 1: spme fibers used during the microextraction technique. fiber type acronym full name volume of coating (mm3) medium-polar pdms 30 polydimethylsiloxane, 30µm 0.132 polar pa 85 polyacrylate, 85 µm 0.521 headspace solid-phase microextraction procedure the hs-spme extraction after optimization was performed by placing 0.3 g of freshly ground neem leaf powder in 12 ml crimp-top headspace vial (diameter 2 cm, height 6.7 cm), capped with porous poly-tetrafluoroethylene (ptfe) silicon rubber septum. the sample in the headspace vial was heated by supporting them with a clamp in a hot water bath (60o c). after 10 minutes, needle of the spme device was pierced the septum of the vial and the fiber was immersed to the headspace of the sample for 30 minutes, 1 cm above the leaf powder, which was kept at 60o c. after extraction, the fiber was inserted into the hot injector of the gc systems for analysis. gas chromatography–mass spectroscopy (gc-ms) analysis conditions chromatographic analysis was performed using an agilent technologies 7890a gas chromatograph (palo alto, ca) equipped with an agilent technologies 5975c inert xl ei/ci mass selective detector. a db-5ms fused silica capillary column of 30 m×0.25 mm i.d.×0.25 µm film thickness (j & w scientific, folsom, ca) was used. helium was used as the carrier gas at a flow rate of 1ml/min and detector gases were hydrogen and air. the temperature was programmed as follows: initial oven temperature was 40o c for 3minutes, and then was increased at 10o c/min up to 280o c, where it was held for 3 minutes and maintained constant for 30 minutes. the injection port was in the splitless mode. spme fiber was introduced in the injector port, held at 250o c for chromatographic analysis and remained in the inlet for 30 minutes. identification of components in the sample was based on the chromatographic 14 criteria (retention times) and ms spectral library at the chemistry department in university of sri jayewardenepura, sri lanka. 2.10 analysis of data all data were subjected to one-way analysis of variance (anova) using the “minitab”, version 14.0. tukey’s multiple comparison test was used to separate mean values of the experiments, where significant differences existed (p<0.05). probit analysis was used to estimate lc50 values to determine the lethal concentrations needed to kill 50% of weevils. 3.0 results and discussion 3.1 contact insecticidal effect the contact toxic effect of neem leaf powders on the survival of maize weevil adults are presented in table 2. tested leaf powders of a. indica significantly (p˂0.05) reduced the longevity of adults on treated maize grains apart from the control which gave no weevil mortalities. at highest dose of 33.33 % w/w, all the leaf powders produced contact weevil mortalities ranging from 34–100% and 7-52% at the lowest dosage (3.33% w/w) within 1-10 day time period. accordingly, a. indica leaf powders showed its superiority in suppressing sitophilus zeamais populations evoking 100% contact mortality, at the highest dosage after 9 days of weevil exposure. moreover, as the exposure time proceeds, there was a progressive increase in the insecticidal potential of the botanical to the maize weevils, resulting in considerably high mortality of s. zeamais. according to some previous literature, neem leaves were sufficient enough in protecting cacao beans and jola seeds from insects and found to exhibit insecticidal activities over ephestia cautella. additionally, these leaves have been placed in 6-8 cm layers which then protected the grains from sitophilus oryzae, sitotroga cerealella and rizopertha dominica. it was also reported that dried neem leaves have been admixed with stored paddy or a thick layer of 20-30 cm leaves between the bags and floor to protect stored paddy from insects moreover, neem leaves are evidenced in protecting rice and wheat grains stored in gunny bags against wide array of grain boring insects. furthermore, neem leaf powder displayed toxicity to callosobruchus chinensis and absolute grain protection on rizopertha dominica for 6 months in storage while reducing adult emergence of corcyra cephalonica by 52-56% and larval mortality by 40-45% in sorghum (prakash and rao, 1997). the neem leaf powder on application usually covers the testa of maize grains, serving as food poison to the adult insects (ileke and oni, 2011). azadirachtin, the neem’s agent of controlling insects (rejitha et al., 2014), produces an antiperistalitic wave in the insect alimentary canal thus creating a vomiting sensation in the insect. due to that lethal sensation, the insect does not feed on the neem treated surfaces and their ability to swallow is also blocked thus eventually leading to their death (lokanadhan et al., 2012). perera et al. /journal of tropical forestry and environment vol. 8, no. 01 (2018)/ 10-24 15 table 2: contact toxic effect of a. indica leaf powders on s. zeamais at 24 hour interval up to 10 days. *means followed by the same letters in each row are not significantly different according to the tukey’s test at p<0.05; *mean percentage contact mortality±sd for five replicates (n = 100); had – days after treatment; nd=not detected 3.2 fumigation insecticidal activity the evaluation of fumigation toxicity of a. indica leaf powder against maize weevils, revealed its potential of controlling test insects as a fumigant (table 3). least fumigation mortality (29.00±2.24%) was observed when the maize grains were treated at 3.33% w/w of lowest dose, while the highest dose (33.33% w/w) was producing 77.00±2.74% s. zeamais mortality after 10 day time interval while positive control displaying no mortality. farmers in sri lanka have long been used to burn neem leaves to generate smoke for fumigation against insect pests of stored paddy and pulses (ranasinghe, 1984; saxena, 2009). it is noted that the pungent smell of this natural fumigant not only kills insect pests but also affects them negatively by acting as feeding and oviposition deterrent, mating disruptor and growth inhibitor in the protection of stored grains (lokanadhan et al., 2012) and would not allow the formation of resistant races of the insect which is quite common with most of the synthetic insecticides (shukla et al., 2007). it was also recorded that neem leaf volatiles drastically reduces the hatchability of the cotton bollworm, earias vittella (prakash and rao, 1997). mulungu et al. (2007) and yohannes et al. (2014) have noted that fumigation mortality occurs as a result of physical barrier effects exerting by the plant powders on insects. in that context, powders have the tendency to block spiracles of the insects thus causing asphyxiation and impair physiological processes by penetrating the insect body via respiration system ultimately leading to the death of insects (melo et al., 2015). *mean % contact mortality ± sd time/ had dose (w/w %) control 3.33 10.00 16.67 23.33 33.33 1 nd 7.00±2.74b 11.00±2.74bc 13.00±2.74c 16.00±4.18c 34.00±5.48d 2 nd 9.00±2.24 16.00±4.18c 24.00±2.24 30.00±0.00e 48.00±2.74f 3 nd 12.00±2.74b 18.00±2.74c 29.00±4.18d 42.00±2.74e 57.00±2.74f 4 nd 13.00±4.47b 26.00±2.24c 32.00±2.74d 43.00±2.74e 68.00±2.24f 5 nd 16.00±2.74b 30.00±5.00c 34.00±3.54c 44.00±2.74d 72.00±2.74e 6 nd 23.00±2.74b 34.00±4.18c 38.00±2.74d 46.00±2.24e 79.00±2.24f 7 nd 26.00±4.18b 41.00±4.18c 47.00±4.47c 62.00±2.74d 86.00±5.00e 8 nd 39.00±2.24b 57.00±4.47c 68.00±2.74d 71.00±4.18d 94.00±4.18e 9 nd 42.00±2.74b 65.00±5.00c 73.00±2.74d 82.00±2.74e 100.00±0.00f 10 nd 52.00±4.47b 72.00±2.74c 76.00±4.18c 84.00±4.18d 100.00±0.00e 16 table 3: fumigation toxic effect of a. indica leaf powders on s. zeamais at 24 hour interval up to 10 days. *means followed by the same letters in each row are not significantly different according to the tukey’s test at p<0.05; *mean percentage fumigation mortality ± sd for five replicates (n = 100); had – days after treatment; nd=not detected the leaf powders of a. indica exerted significant (p˂0.05) contact and fumigation insecticidal activities against s. zeamais with respect to the median lethal dose (ld50) values after 9 days of exposure (table 4). however, it was observed that the fumigation treatment (4.48 g) was 3 times less active against the maize weevils than the contact treatment (1.56 g). table 4: median lethal doses (ld50) of s. zeamais due to a. indica leaf powders after 9 days of exposure. treatment ld50 (g) confidence interval slope±se p value lower upper contact 1.56 1.17 1.93 0.73±0.08 0.00 fumigation 4.48 3.66 5.52 0.52±0.08 0.00 95% lower and upper fiducial limits are shown in parenthesis ld50 – lethal dosage that kills 50% of the population 3.3 contact and fumigation repellent activity mean percentage contact and fumigation repellency of s. zeamais adults to maize grains treated with varying leaf powder doses of a. indica are presented in figure1. *mean % fumigation mortality ± sd time/ had dose (w/w %) control 3.33 10.00 16.67 23.33 33.33 1 nd 0.00±0.00a 0.00±0.00a 2.00±2.74a 8.00±4.47b 14.00±2.24c 2 nd 0.00±0.00a 0.00±0.00a 5.00±5.00b 10.00±3.54b 21.00±4.18c 3 nd 0.00±0.00a 3.00±4.47a 11.00±4.18c 14.00±4.18c 25.00±3.15d 4 nd 8.00±2.74b 13.00±2.74b 21.00±2.24c 24.00±2.24c 33.00±4.47d 5 nd 12.00±2.74b 16.00±2.24b 25.00±2.54c 28.00±2.74c 39.00±4.18d 6 nd 13.00±2.74b 18.00±4.47b 30.00±0.00c 32.00±2.74c 47.00±2.74d 7 nd 19.00±4.18b 27.00±4.47c 35.00±3.54d 40.00±3.54d 49.00±2.24e 8 nd 23.00±2.74b 32.00±4.47c 37.00±4.47c 43.00±2.74d 54.00±2.24e 9 nd 21.00±4.18b 46.00±5.48c 53.00±2.74d 59.00±2.24d 67.00±2.74e 10 nd 29.00±2.24b 48.00±2.74c 60.00±0.00d 65.00±0.00e 77.00±2.74f perera et al. /journal of tropical forestry and environment vol. 8, no. 01 (2018)/ 10-24 17 figure 1: contact and fumigation repellency effect of neem leaf powder on s. zeamais within an hour of weevil exposure. it was evidenced that s. zeamais adults were more significantly susceptible to contact treatments than to the fumigation treatments with regards to repellency. leaf powders of a. indica hindered the orientation of 74% and 47 % of adults in contact and fumigation treatments respectively at the highest dose of 33.33% w/w. it is noteworthy that all tested doses in both treatments produced less than 50% repellent effects on maize weevils except for 23.33% and 33.33% w/w doses in contact treatment. the relatively lower fumigation effects would be due to the low potentiality of neem leaf volatiles as fumigants which may not be enough to repel maize weevils. in sri lanka, chopped green leaves of a. indica were being kept over the heap of paddy in a container to hinder the insect orientation towards the paddy or to repel the insects from the grains (saxena, 2009). 3.4 preliminary qualitative phytochemical screening table 5 shows the list of classes of plant secondary metabolites present in a. indica leaves that accentuate some concrete evidences on their defensive roles against insect pests. the results indicated that methanol leaf extract exhibited the presence of the highest number of phytochemicals whereas hexane and aqueous extracts demonstrated the lowest. phenols were present in all leaf extracts while saponins were found in none. due to the important role of secondary metabolites, which play in insect-plant interaction that are often involved with plant defense, their bioactivities can be used against stored grain insect pests (rajashekar et al., 2014). thus, the presence of secondary metabolite classes may be a useful indicator for both efficacy and potential of phytochemical bioactivity (gupta et al., 2013). leaf powders of a. indica that were used as bio-insecticides and proved effective on s. zeamais were found to contain various constituents after subjecting them to phytochemical screening that were also comparable to those of other researchers who investigated in this regard. however, there were some changes that somewhat not strictly in line with the content of chemical composition of a. indica grown in sri lanka (biu et al., 2009; 18 krishnaiah et al., 2009; raphael, 2012; gupta et al., 2013; susmitha et al., 2013; shuaibu et al., 2015). these differences in chemical composition of a. indica could be due to the different effects of climatic, seasonal, geographical and environmental factors and also may result from different metabolic pathways in the plant (guo et al., 2015). table 5: phytochemical constituents of azadirachta indica in, hexane, dichloromethane, ethyl acetate, methanol and aqueous extracts. (+)=presence; (-) =absence generally, plants produce a wide array of secondary metabolites that often include insecticidal, repellent, antifeedant or growth retardant properties to control broad spectrum of insect pest damages (mundi and alhassan, 2012). some insects are found to repelled by azadirachtin, isolated from a. indica which is a limonoid in the class of terpenoids at the concentrations as low as few parts per million (defago et al., 2006; adeyemi, 2011). not only that, azadirachtin is a natural insecticide that has also been reported to have strong insecticidal, antifeedant and growth disrupting activities towards insect pests, but with very low toxicity to humans and environment (biu et al., 2009; krishnaiah et al., 2009). tannins are toxic to insects because they bind to salivary proteins and digestive enzymes including trypsin and chymotrypsin resulting in protein inactivation, eventually leading to the death of insects. alkaloids are known as a large class of bitter-tasting nitrogenous compounds that have powerful detrimental effects on animal physiology (adeyemi, 2011). therefore, it can be suggested that compounds found in a. indica leaves either individually or in combination may also be responsible for the observed insecticidal and repellent activities of the maize weevils. additionally, further research on the note of using one or more specific compounds isolated from a. indica against the s. zeamais might be of great importance. phytochemical constituent n-hexane dichloro methane ethyl acetate methanol aqueous alkaloids + (-) (-) (-) + saponins (-) (-) (-) (-) (-) flavonoids (-) (-) (-) (-) + tannins (-) (-) + + (-) steroids (-) + + + (-) terpenoids + (-) + + (-) anthraquinones (-) + + + (-) glycosides (-) + (-) + (-) phlobatannins (-) + (-) (-) (-) coumrins + (-) (-) (-) + phenols + + + + + perera et al. /journal of tropical forestry and environment vol. 8, no. 01 (2018)/ 10-24 19 3.5 analysis of the volatile organic compounds with the view of characterising and identifying which volatile organic compounds might be responsible for the fumigation bioactivity demonstrated by the fresh neem leaf powders in the suppression of s. zeamais, headspace-solid-phase micro extraction coupled with gas chromatography-mass spectrometry (hs-spme/gc-ms) was employed. table 6 presents the area values and the number of volatile organic compounds extracted from headspace of the leaves of a. indica using two different fibers. two fibers of pdms 30 and pa 85 µm were chosen because both combine the best signal-to-noise ratio with maximum extraction of compounds. at present, this study represents the first ever report on the characterization of volatile compounds from the leaves of a. indica by using hs-spme technique. thirty two volatile organic compounds were identified in the leaf of a. indica in different proportions with the two spme fibers. however, higher number of compounds was detected with the medium-polar fiber (pdms 30 µm) exhibiting comparatively greater area percentages/ relative abundances than with the polar fiber (pa 85 µm). the major extracted volatile organic compounds were found to be γ-elemene (24.06%), 3,7(11)eudesmadiene (6.83%), caryophyllene (6.40%), 10s,11s-himachala-3(12),4-diene (6.36%), neoisolongifolene (3.41%), β-selinene (3.35%), 1,4,7-cycloundecatriene,1,5,9,9-tetramethyl (3.31%), βelemene (2.91%), δ-cadinene (2.33%), 2,4-dimethylthiophene (2.31%), longifolene (2.30%) and αcadinene (2.15%) occupying approximately 65.72% of the total spectrum while other compounds were present in amounts less than 2%. chemical class composition of the volatile compounds in the headspace from a. indica leaves are illustrated in table 7. the leaf volatile profile which better extracted from the pdms 30 µm fiber was dominated by 27 aliphatic molecules (74.97%) followed by 5 aromatic molecules (3.36%), where 21 sesquiterpenoids (71.10%) and 4 monoterpenoids (3.47%) occupied the highest composition of aliphatic molecules. the major sesquiterpenoid contributors in the aliphatic molecular framework were, notably γelemene, with the low abundances of 3,7(11)-eudesmadiene, caryophyllene and 10s,11s-himachala3(12),4-diene constituting over 43% of the fragrant headspace of a. indica whilst other constituents present in influential amounts were making a significant contribution in the leaf volatiles of a. indica. in an earlier study, zeringue and bhatnagar (1994) had observed the significance of inhibitory effects exerted by the volatile compounds of neem leaves on the fungal growth and aflatoxin production in aflatoxigenic aspergillus parasiticus cultures. they trapped the volatiles on small tenax glass columns and reported 68 compounds in the gc-ms separation and identification, which were entirely and chemically distinct from those reported in the present study. it must be noted that the above study reported the presence of principal classes of ketones, alcohols, aldehydes, hydrocarbons and miscellaneous compounds while referring 3-hydroxy-2-butanone (19.67%), 2-propanone (12.84%), 2,3butanediol (9.70%), 1-heptanol (5.43%), 4-pentenal (3.83%) and 2-heptenal (2.60%) as the major contributors in neem leaf volatile composition. thus, it is apparent that the differences in the nature and composition of volatile organic compounds of neem were the result of the differences in the extraction protocols. on the other hand, shivashankar et al, (2012) reported the volatile organic compounds present in seed and seed cake of a. indica which analyzed by the same extraction protocol as used as in the present study, the hs-spme/gc-ms. according to their report, most abundant volatile organic components were (z)-9,7-octadecadienal and palmitic acid comprising 25.47% and 14.97% of the total spectrums in a. indica seed and cake respectively. 20 table 6: spme headspace analysis of volatile compounds from leaves of azadirachta indica using pa 85 µm and pdms 30 µm fibers. volatile organic compounda pa 85 µm pdms 30 µm rtb relative peak area (%)* rtb relative peak area (%)* 1 2,4-dimethylthiophene nd 3.587 2.31 2 3,4-dimethylthiophene nd 3.801 0.86 3 bicyclo[4.1.0]hept-2-ene,3,7,7-trimethyl (2-carene) 9.950 0.79 nd 4 4-carene nd 9.955 1.76 5 4-methylene-1-(1-methylethyl) cyclohexene (β-terpinene) nd 10.091 1.71 6 3a,7-methano-3ah-cylopentacyclooctene, 1,4,5,6,7,8,9,9a-octahydro1,1,7-trimethyl-[3ar-(3a.alpha., 7.alpha.,9a.beta)] (clovene) nd 10.319 0.42 7 α-cubebene 10.499 0.57 nd 8 copanene nd 10.504 1.34 9 cyclobuta[1,2,3,4]dicyclopentene,decahydro-3a-methyl-6-methylene-1(1-methylethyl)-, [1s-(1.alpha.,3a.alpha.,3b.beta.,6a.beta.,6b.alpha)] (βbourbonene) nd 10.632 1.01 10 cyclohexene,1-ethenyl-1-methyl-2,4-bis(1-methylethenyl)—[1s(1.alpha.,2.beta.,4.beta.)] (β-elemene) 10.691 1.35 10.706 2.91 11 isocaryophillene nd 10.942 0.79 12 caryophyllene nd 11.129 6.40 13 γ-elemene 11.233 22.39 11.332 24.06 14 4,7-methanoazulene,1,2,3,4,5,6,7,8-octahydro-1,4,9,9-tetramethyl,[1s(1.alpha.,4.alpha.,7.alpha.)] (β-patchoulene) 11.449 1.02 nd 15 neoisolongifolene nd 11.501 3.41 16 1,4,7-cycloundecatriene,1,5,9,9-tetramethyl 11.551 0.40 11.590 3.31 17 1h-cyclopropazulene,decahydro-1,1,7-trimethyl-4-methylene-[1ar(1a.alpha.,4a.beta.,7.alpha.,7a.beta.,7b.alpha)] (alloaromadedrene) 11.615 0.73 11.813 1.33 18 naphthalene,1,2,4a,5,8,8a-hexahydro-4,7-dimethyl-1-(1-methylethyl)-, (1.alpha.,4a.beta.,8a.alpha) (α-cadinene) 11.993 1.06 12.015 2.15 19 naphthalene,decahydro-4a-methyl-1-methylene-7-(1-methylethenyl),[4ar-(4a.alpha.,7.alpha.,8a.beta)] (β-selinene) nd 12.084 3.35 20 bicyclo[3.1.1]hept-2-ene, 2,6-dimethyl-6-(4-methyl-3-pentenyl) (α-bergamotene) 12.269 0.56 nd 21 1h-benzocycloheptene,2,4a,5,6,7,8-hexahydro-3,5,5,9-tetramethyl (β-himachalene) nd 12.283 1.06 22 naphthalene,1,2,3,5,6,8a-hexahydro-4,7-dimethyl-1-(2-methylethyl) (δ-cadinene) 12.385 0.61 12.407 2.33 23 β –humelene 12.452 0.42 12.468 0.85 24 10s,11s-himachala-3(12),4-diene 12.572 2.16 12.609 6.36 25 naphthalene,1,2,3,4,4a,5,6,8a-octahydro-4a,8-dimethyl-2-(1methylethyldiene) (3,7(11)-eudesmadiene) 12.655 2.18 12.701 6.83 26 longifolene 12.809 0.26 12.878 2.30 27 azulene,1,2,3,4,5,6,7,8-octahydro-1,4-dimethyl-7-(1-methylethenyl)-, [1s-(1.alpha.,4.alpha.,7.alpha.)] (α-guaiene) 12.904 0.17 13.117 0.54 28 5-allylsulfanyl-1-(4-methoxy-phenyl)-1h-tetrazole nd 13.559 0.40 29 cadina-1(10),6,8-triene nd 13.657 0.07 30 cycloisolongifolene,8,9-dehydro nd 13.794 0.10 31 naphthalene,1,2,3,5,6,7,8,8a-octahydro-1,8a-dimethyl-7-(1methylethenyl)-, [1s-(1.alpha.,7.alpha.,8a.alpha.)] (valencene) nd 15.146 0.25 32 1-(2-methyoxyphenyl)-2,5-dihydro-1h-pyrrole-2,5-dione nd 15.366 0.12 total 34.67 78.33 acompounds listed in order of elution, brt=retention time, *data are expressed as percentage of the total peak area, nd=not detected table 7: chemical class composition of volatile organic compounds of leaves of azadirachta indica. perera et al. /journal of tropical forestry and environment vol. 8, no. 01 (2018)/ 10-24 21 molecular framework class percentage (%) pa 85 µm pdms 30 µm aliphatic monoterpenoids 1.35 3.47 sesquiterpenoids 33.32 71.10 other 0.40 aromatic purine nucleosides 0.07 other 3.29 total 34.67 78.33 several reports have demonstrated that the plant volatiles produce insect mortality by inhibiting acetylcholinesterase enzyme and bio-fumigants could be neurotoxic based on behavioral symptoms similar to those produced by organophosphates (rajashekar et al., 2014). in that account, the insecticidal and repellent nature of the leaf powders of a. indica manifested by adult insects of s. zeamais in both contact and vapor forms may be linked to the main volatile compounds extracted reportedly acting alone or in synergy with other minor constituents (adjalian et al., 2015). monoterpenoids exhibit acute toxic, repellent and antifeedant effects or effects on growth and development or reproduction against target insect species while establishing their biological activity as ovicides, fumigants and contact toxicants on various insect pests. they are typically volatile and rather lipophilic compounds that can penetrate into insects rapidly interfering with their physiological functions (lee, 1997). accordingly, β-himachalene, a monoterpenoid has been found to possess insecticidal properties as reported by singh (2014). meanwhile sesquiterpenoids have already been better proven for their repellent activities against a wide array of insect pests (gross and coats, 2014). caryophyllene and its derivatives reportedly possess acaricidal, insecticidal, repellent, attractive and antifungal properties. during the laboratory experiments in previous attempts it has been found that this sesquiterpene also mediates the behavioural changes in aedes aegypti leading to a reduction in oviposition, thus suggesting that the compound could be used in controlling the spread of dengue mosquito (santos da silva et al., 2015). additionally, alloaromadendrene, humulene and caryophyllene had been proved to be the the most active toxic sesquiterpenes against the south asian termites (neotermes spp.) by messer et al (1960) and choong and achmadi (1996). furthermore, alloaromadendrene is one of the major components in crude resin of dipterocarupus trees that is responsible for the insecticidal properties of this resin against insect pests (gijsen et al., 1995). α-bergamotene, a volatile defense compound as well as a sesquiterpene performs multiple activities including, repelling herbivorous invaders, decreasing their rates of oviposition and also recruiting their natural predators (redei, 2008). structural characteristics of compounds such as shapes, degree of saturation and types of functional groups influence the insecticidal activity and species-specific susceptibility. the potencies of compounds vary because their chemical properties and structural diversities can elicit different degrees of toxicity (lee, 1997). additionally, grodnitzky and coats (2002) developed quantitative structure-activity relationship (qsar) models to explain the chemical basis or importance of electronic properties of compounds responsible for various biological and physiochemical effects, that provide insight into the important regions of the molecules responsible for their insecticidal properties. they further suggested that the compounds in aliphatic framework may also have a different mode of action than the compounds in the aromatic model. 22 4. conclusion secondary metabolite and biological experiments performed during the current study confirm the eco-chemical phenomena underscoring the insecticidal and repellent properties of neem leaf powders observed against the maize weevil infestations. though a. indica leaves have long been successfully used for the protection of stored grains from insect pest attack in agriculture, it is suggested that further investigations should be directed in line with the above findings towards the quantification and exploration of biological aspects of the principle volatiles produced by neem leaves identified during this study, thereby providing new insights on how a. indica leaves showcase their insecticidal and repellent activities, thus making them available to humankind and prospering sustainable development of the nature. references adelino de melo, b., molina-rugama, a.j., haddi, k., leite, d.t., eduardo de oliveira, e., 2015. repellency and bioactivity of caatinga biome plant powders against callosobruchus maculatus (coleoptera: chrysomelidae: bruchinae). florida entomologist. 98(2), 417-423. adeyemi, m.m.h., 2011. a review of secondary metabolites from plant materials for post harvest storage. international journal of pure and applied sciences and technology. 6(2), 94-102. adeyemi, m.m., mohammed, m., 2014. prospect of antifeedant secondary metabolites as post harvest material. international journal of innovative research in science, engineering and technology. 3(1), 8701-8708. adjalian, e., sessou, p., odjo, t., figueredo, g., kossou, d., avlessi, f., et al, 2015. chemical composition and insecticidal and repellent effect of essential oils of two premna species against sitotroga cerealella. journal of insects. 1-6. biu, a.a., yusufu, s.d., rabo, j.s., 2009. phytochemical screening of azadirachta indica (neem) (meliaceae) in maiduguri, nigeria. bioscience research communications. 21(6), 281-283. choong, e.t., achmadi, s.s., 1996. utilization potential of the dipterocarp resources in international trade, in: schulte, a., schone, d. (eds), dipterocarp forest ecosystem: towards sustainable management. world scientific publishing co. pte. ltd., singapore, pp. 503. coats, j.r., karr, l.l., drewes, c.d., 1991. toxicity and neurotoxic effects of monoterpenoids in insects and earthworms, in: hedin, p.a. (eds.), naturally occurring pest bioregulators: developed from symposia sponsored by the division of agrochemicals at the 197th and 198th national meetings of the american chemical society and the international chemical congress of pacific basin societies at the 1989 international chemical congress of pacific basin societies. american chemical society, washington, dc. pp. 306. defago, m., valladares, g., banchio, e., carpinella, c., palacios, s., 2006. insecticide and antifeedant activity of different plant parts of melia azedarach on xanthogalera luteola. fitoterapia. 77, 500505. department of agriculture, 2013. annual performance report 2012. department of agriculture, peradeniya. dubey, n.k., srivastava, b., kumar, a., 2008. current status of plant products as botanical pesticides in storage pest management. journal of biopesticides. 1(2), 182-186. el-wakeil, n.e., 2013. botanical pesticides and their mode of action. gesunde pflanzen. 65, 125-149. gijsen, h.j.m., wijnberg, j.b.p.a., de groot, a., 1995. structure, occurrence, biosynthesis, biological activity, synthesis and chemistry of aromadendrane sesquiterpenoids, in: barrera, j.b., gijsen, h.j.m., gonzalez, a.g., de groot, ae., prota, g. (eds.), fortschritte der chemie organischer perera et al. /journal of tropical forestry and environment vol. 8, no. 01 (2018)/ 10-24 23 naturstoffe/ progress in the chemistry of organic natural products. springer vienna, vienna, pp. 167. grodnitzky, j.a., coats, j.r., 2002. qsar evaluation of monoterpenoids’ insecticidal activity. journal of agricultural and food chemistry. 50, 4576-4580. gross, a.d., coats, j.r. 2014. can green chemistry provide effective repellents, in: frances, s.p., strickman, d. (eds), insect repellents handbook (2nd ed.). crc press, pp. 81. guo, s.s., you, c.x., lian, j.y., zhang, w.j., geng, z.f., wang, c.f., du, s.s., lei, n., 2015. chemical composition and bioactivities of the essential oil from etlingera yunnanensis against two stored product insects. molecules. 20, 15735-15747. gupta, a.k., ahirwar, n.k., shinde, n., choudhary, m., rajput, y.s., singh, a., 2013. phytochemical screening and antimicrobial assessment of leaves of adhatoda vasica, azadirachta indica and datura stramonium. uk journal of pharmaceutical and biosicences. 1(1), 42-47. harborne, j.b., 1998. phytochemical methods: a guide to modern techniques of plant analysis, eds. chapman and hall, london. hsu, c.c., dobberstein, r.h., bingel, a.s., fong, h.h., farnsworth, n.r., morton, j.f., 1981. biological and phytochemical investigation of plants xvi: strumpfia maritime (rubiaceae). journal of pharmaceutical sciences. 70 (6), 682-683. ileke, k.d., oni, m.o., 2011. toxicity of some plant powders to maize weevil, sitophilus zeamais (motshulsky) [coleoptera: curculionidae] on stored wheat grains (triticum aestivum). african journal of agricultural research. 6(13), 3043-3048. isman, m.b., 2006. botanical insecticides, deterrents, and repellents in modern agriculture and an increasingly regulated world. annual review of entomology. 51, 45-66. khater, h.f., 2012. prospects of botanical biopesticides in insect pest management. pharmacologia. 3(12), 641-656. krishnaiah, d., devi, t., bono, a., sarbatly, r., 2009. studies on phytochemical constituents of six malaysian medicinal plants. journal of medicinal plants research. 3(2), 67-72. lee, s.k., 1997. insecticidal properties of monoterpenoids and their derivatives as a new natural means of crop protection. retrospective theses and dissertation, paper 11478. lokanadhan, s., muthukrishnan, p., jeyaraman, s., 2012. neem products and their agricultueal applications. journal of biopesticides. 5,72-76. messer, j., peters, g.a., bennet, w.a., 1960. cause of death and pathological findings in 304 cases of bronchial asthma. dis. chest. 38, 616-624. moef&cc, dbt, 2011. biology of zea mays (maize). series of crop specific biology documents. ministry of environment, forests and climate change and the department of biotechnology, ministry of science and technology, new delhi. prakash, a., rao, j., 1997. botanical pesticides in agriculture. crc press, boca raton, pp 36-38. mulungu, l.s., lupenza, g., reuben, s.o.w.m., misangu, r.n., 2007. evaluation of botanical products as stored grain protectant against maize weevil, sitophilus zeamais (l.) on maize. journal of entomology. 4(3), 258-262. mundi, a.d., alhassan, u., 2012. preliminary determination of phytochemicals in some plant seed powders that are effective in controlling storage bruchid of bambara groundnut. international journal of science and advanced technology. 2(9), 54-59. ortega, c., a., 1987. insect pests of maize: a guide for field identification. international maize and wheat improvement center, mexico. 24 rajashekar, y., raghavendra, a., bakthavatsalam, n., 2014. acetylchoinesterase inhibition by biofumigant (coumarin) from leaves of lantana camara in stored grain and household insect pests. biomed research international. 1-6. ranasinghe, m.a.s.k., 1984. neem and other promising botanical pest control materials from sri lanka, international workshop on the use of botanical pesticides, international rice research institute, manila, pp 15. raphael, e., 2012. phytochemical constituents of some leaves extract of aloe vera and azadirachta indica plant species. global advanced research journal of environmental science and toxicology. 1(2), 14-17. redei, g.p., 2008. encyclopedia of genetics, genomics, proteomics and informatics, third ed. springer, new york, pp. 1001. rejitha, t.p., reshma, j.k., mathew, a., 2014. study of repellent activity of different plant powders against cockroach (periplanata americana). international journal of pure and applied bioscience. 2(6), 185-194. santos da silva, r.c., millet-pinheiro, p., bezerra da silva, p.c., gomes da silva, a., vanusa da silva, m., navarro, d.m.a.f., et al., 2015. (e)-caryophyllene and α-humulene: aedes aegypti oviposition deterrents elucidated by gas chromatography-electrphysiological assay of commiphora leptophloeos leaf oil. plos one. 10(12), 1-14. saxena, r.c., 2009. practical applications of neem against pests of stored products. acesso 23(5), 110,114. shivashankar, s., roy, t.k., krishna moorthy, p.n., 2012. headspace solid phase micro extraction and gc/ms analysis of the volatile components in seed and cake of azadirachta indica a. juss. chemical bulletin of “politehnica” university of timisoara. 57(71), 1-6. shu’aibu, i., hamman, j.b., goje, l.j., mu’inat, a.m., jauro, h.a., kabiru, m.y., 2015. phytochemical analysis and evaluation of bacteriostatic effect of neem (azadirachta indica) leaves on some clinical bacterial isolates. journal of harmonized research in applied sciences. 3(3), 152-157. shukla, r., srivastava, b., kumar, r., dubey, n.k., 2007. potential of some botanical powders in reducing infestation of chickpea by callosobruchus chinensis l. (coleoptera: bruchidae). journal of agricultural technology. 3(1), 11-19. singh, d., 2014. advances in plant biopesticides. sushmitha, s., vidyamol, k.k., ranganayaki, p., vijayaragavan, r., 2013. phytochemical extraction and antimicrobial properties of azadirachta indica (neem). global journal of pharmacology. 7(3), 316-320. yohannes, a., asayew, g., melaku, g., derbew, m., kedir, s., raja, n., 2014. evaluation of certain plant leaf powders and aqueous extracts against maize weevil, sitophilus zeamais motsch. (coleoptera: curculionidae). asian journal of agricultural sciences. 6(3), 83-88. zeringue, h.j.j.r., bhatnagar, d., 1994. effects of neem leaf volatiles on submerged cultures of aflatoxigenic aspergillus parasiticus. applied and environmental microbiology 60, 3543-3547. chapter five: discussion ratnasekera & rupasingha /journal of tropical forestry and environment vol. 5. no 02 (2015) 67-75 67 morpho-physiological dynamics of weedy rice seeds collected from two contrasting agro-ecological zones in sri lanka d. ratnasekera 1* and k.m.a.s.k. rupasingha 1 1 department of agricultural biology, faculty of agriculture, university of ruhuna, sri lanka date received: 29-08-2015 date accepted: 10-10-2015 abstract weedy rice (oryza sativa l. f. spontanea), seeds remain a longer period in soils at different depths enriching soil seed bank and that contribute to the success of weedy rice as a “weed.” hence basic information on the level of longevity, dormancy and germination behaviour of weedy rice seeds with relation to its morphology is very important to implement efficient control measures. in this study, weedy rice seeds were collected from six infested locations in ampara and matara districts representing two different agro-ecological zones in sri lanka. two widely grown improved varieties (at 362 and bg 379-2) were assembled as check lines. thirty panicles per population were randomly collected from each location to determine their morphological characteristics including awn lengths, seed shape, hull colour, pericarp colour along with physiological phenologies such as degree of dormancy, viability, longevity and rate of survival. significant variability of seed shape, awn length, hull colour and pericarp colour was observed. germination rate and survival rates were highly variable and closely associated with awn characteristics. our study clearly indicated that prolong longevity (more than 24 weeks) and viability of weedy rice seeds in field conditions implying their key role as a weed by enriching soil seed bank. awned populations are dormant and influence weedy rice population dynamics leading to the competitiveness of this weed. therefore, management practices have essentially to take them into account and be adapted accordingly. further, this study inferred that the morpho-physiological variation of the weedy rice seed populations was not associated with the agro-ecological conditions; for example, the dry and the wet zone suggesting rapid seed mediated gene flow throughout the country. keywords: dormancy, germination, seed viability, seed morphology 1. introduction weedy rice (oryza sativa complex) has become the most dominant and competitive conspecific weed relative of cultivated rice (oryza sativa l.) that occurs in rice fields worldwide (michael et al., 2010). it is the main competitor with cultivated rice, affecting both growth and yield, especially in regard to space and nutrient availability (zainudin et al., 2010). weedy rice is vegetatively very similar to cultivated rice but has some key differences viz. shattering seed dispersal, red pericarp pigmentation, * correspondence: disnaratnasekera@gmail.com tel: +94 718232808 issn 2235-9370 print/issn 2235-9362 online © university of sri jayewardenepura 68 and the ability of seeds to persist in the soil (delouche et al., 2007). the management of weedy rice infestations is much more difficult than that of other rice weeds because of the high biological similarity with cultivated rice and the extended germination over a long period of rice growth (fogliatto et al., 2010). weedy rice has close affinity with cultivated rice, in terms of morphological and physiological characteristics (fogliatto et al., 2011). this similarity has even led weedy rice to be classified as the same species as cultivated rice (vaughan et al., 2001). morphologically, weedy rice is highly variable in almost all the vegetative and reproductive characteristics with each other and appears to be an intermediate between wild and cultivated rice (cao et al., 2006). in addition, it is considered as a useful germplasms, as it has successfully adapted to the natural growing conditions (heu et al., 1990). it also has many useful genes for cold tolerance (chang et al., 2004), grain quality and germination characteristics (ma et al., 2008) and high salinity and drought tolerance (jiang et al., 1985). weedy rice was first identified in mid 1990’s as a threat from vavunia, ampara, and batticaloa districts (marambe and amarasinghe, 2000) and at present that is most common in all rice growing areas in sri lanka. the superior competitive ability of weedy rice over cultivated rice has contributed to its rapid spread in the country (abeysekera et al., 2010). the seed-mediated gene flow of weedy rice along with the long-distance exchange of farmer-saved rice seeds between weedy-rice contaminated regions in sri lanka has significant influence in spreading weedy rice throughout the country (he et al., 2014). lack of a selective herbicide for the control of weedy rice, or other effective measures, has made its control a subject of national significance in the country. morphological traits such as seed colour and seed shapes and awn characteristic are highly variable in weedy rice while physiological traits such as degree of dormancy, germination ability, viability and longevity also showed high diversity. higher levels of seed shattering and seed dormancy have enriched the soil seed bank of weedy rice in infested fields. seeds in the soil seed bank may germinate as soon as conditions are favourable (e.g., soil moisture, oxygen, and temperature), while other seeds will germinate at later days or when other factors change. the variable and prolonged periods during which seeds remain dormant are major factors that contribute to the success of weedy rice as a “weed”. strategies for the control of weedy rice are diverse and their implementation depends on the specific site conditions. however, any control measure should aim to reduce the weedy rice seed bank in soil in the medium or long term (labrada, 2010). weedy rice seed banks together with other seed characteristics therefore play an important role in determining the severity of infestation in rice fields (abeysekera et al., 2010). it also highlighted the importance of testing germination behaviour of weedy rice that similar to field conditions to implement efficient control measures. this study attempted to determine the basic seed characteristics and physiological phenologies viz. germination percentage, viability over time under field conditions and survival rate with relation to contrasting ecological conditions. the information gathered in this study will provide a useful guideline for designing effective strategies to control and manage weedy rice in sri lanka. 2. methodology 2.1 sample collection an extensive field survey was carried out at ampara (representing dry zone) and matara (representing wet zone) districts in sri lanka and total of six weedy rice infested locations were selected intentionally as sampling sites. the selected sites were akuressa, thihagoda and mulatiyana from matara district and akkareipattu, ampara and lahugala from ampara district. panicles from 30 individuals were collected from each location twice in yala and maha season in year 2012 and 2013 and tested separately. ratnasekera & rupasingha /journal of tropical forestry and environment vol. 5. no 02 (2015) 67-75 69 2.2 seed germination and morphology seed morphology was recorded by considering awn traits, seed shape, seed size and pericarp pigmentation. the collected mature seeds were dried to 13% of moisture and 10 weedy rice seeds were randomly collected from each panicle per individual and totally 300 seeds from each population, mixed well and randomly collected 100 seeds per one population were used for dormancy and germination test. weedy rice seeds were soaked in water for 24 hours, covered for 24 hours by cloth bag (standard germination percentage testing method) and were kept on the humid filter paper in the petri dish with sufficient light. every population was tested four times and germinated seeds were transferred into mud trays and healthy plants were counted after 21 days. survival rate was assessed as the percentage of germinated seeds. the rate of seed germination was calculated according to maguire (1962) using gr=σdn/σn where, d is the number of days counted from the beginning of sprouting and n is the number of newly emerged seedlings on day d. 2.3 seed viability germination and viability of samples were tested in all test lines before commencing the experiment. seeds were soaked for 18 hours in water and select the 100 seeds and they were split in two halves trough embryo. splited seeds were kept in 1% triphenyl-tetrazolium chloride (ttc) solution for two hours in dark for staining and reddish-pink stained seeds were counted as viable seeds. 2.4 burial test the burial test was conducted twice during 2013 in a rice field of the experimental garden at faculty of agriculture, university of ruhuna, sri lanka. weedy rice seeds collected from different locations in each district were mixed well to get a representative sample, and they were put into separate nylon bags at the rate of 200 seeds per bag. four bags representing each district, but collectively three locations from each district were prepared per each depth for the burial test. in addition to weedy rice two widely grown improved varieties (at 362 and bg 379-2) were included in the study as check lines. bags were buried 15 and 30 cm depths in paddy field respectively with four replicates. over a period of 24 weeks, bags of the buried seeds were dug up at two-week intervals commencing from the four weeks after burying (wab) for testing their viability and germination ability. 3. results 3.1 seed morphological diversity our results showed that there was a great diversity in seeds in terms of seed shape, awn length, hull colour and pericarp colour. however, those variations showed no association with agro-ecological conditions. morphological and topographical characteristics of plant organs such as the shape and size of seeds and the structure of incidental features have been useful weapons in identifying and classifying the plant and weed species (noda et al., 1985; prathepha, 2009). weedy rice seeds collected from matara and ampara districts showed greater variation in awn length, which varied from 0 (awnless) to 10 cm (figure 1a). a considerable diversity was observed in seed shape (figure 1b) and hull colour, which varied from pale white to ashy-black (figure 1c). pericarp colour varied from white to brownish red (figure 1d). the variability observed were comparatively distributed among populations as well as within the populations in same extend in both 70 locations. the plants observed from the study showed grains with and without awns. the size and the colour of the awn were also highly variable. figure 1: morphological variability of weedy rice seeds collected from ampara and matara districts. table 1: percentages of seed morphological traits of weedy rice collected from matara and ampara districts in 2012-2013. population hull colour (%) pericarp colour (%) awn length (%) seed shape (%) s b g r br w l m a l i ro akuressa 60 10 30 88 8 4 25 35 40 30 45 25 thihagoda 70 5 25 80 15 5 22 26 52 32 43 25 mulatiyana 62 13 25 90 6 4 48 34 18 30 55 15 ampara 50 22 28 81 15 4 30 25 45 45 43 12 akkareipattu 56 15 29 83 11 6 35 25 40 48 38 14 lahugala 63 16 21 81 12 7 50 32 18 55 35 10 a=awnless; b=black; br=brown; g=gray; i=intermediate; l=long; m=medium; r=red; ro=round; s=straw; w=white referring to all populations, straw hull colour seeds occur in a higher percentage (>50%) than black (<25%) and gray (<30%) hull coloured seeds. the pericarp colour red is more prominent (>80%) compare to white pericarp seeds (<7%) (table 1). a. variation in awn length b. variation in seed shapes c. variation in hull colour d. variation in pericarp colour ratnasekera & rupasingha /journal of tropical forestry and environment vol. 5. no 02 (2015) 67-75 71 3.2 dormancy and germination rate the degree of seed dormancy of weedy rice was not uniform. the lahugala (lh) population of ampara district representing dry zone showed strong dormancy during 5-50 dah while the rest of the two populations from the same district displayed medium seed dormancy similar to check lines used. the mulatiyana (ml) population of matara district representing wet zone has relatively high degree of dormancy similar to lahugala population inferring variation of the weedy rice populations was not associated with the agro-ecological conditions. in general, all test lines required nearly three months to be overcome dormancy (table 2). the majority of tested weedy rice populations had the medium seed dormancy as same with the cultivated rice bg 379/2 and at 362. however, weedy rice populations do not had gp of seeds uniformly as compared to cultivated rice. this trait may be contributed to the reason why weedy rice is present in the field for the succeeding seasons when they meet favourable conditions in the long run. table 2: dormancy and germination behaviour of weedy rice populations collected from ampara and matara districts representing 03 locations from each district. 5 dah 20 dah 50 dah 80 dah 100 dah 120 dah 140 dah ak 10.47 d 73.41 d 85.77 b 94.66 a 96.64 b 94.68 b 68.53 b am 25.42 e 73.66 d 87.77 b 98.00 b 98.34 b 90.66 a 66.66 b lh 2.66 a 11.00 a 63.67 a 93.83 a 98.64 b 85.98 a 60.22 ab th 30.22 e 74.26 d 90.66 b 99.00 b 98.66 b 95.33 b 70.32 b ml 9.76 cd 46.54 b 58.78 a 98.66 b 90.00 a 87.00 a 54.66 a ar 27.54 e 60.75 c 90.00 b 98.72 b 98.00 b 90.00 a 61.21 ab bg379/2 5.51 bc 58.44 c 87.45 b 98.00 b 98.33 b 95.00 b 73.65 c at362 3.87 ab 57.66 c 90.33 b 99.00 b 98.00 b 91.00 a 73.00 c dah=days after harvest; ak=akkareipattu; am=ampara; lh=lahugala; th=thihagoda; ml=mulatiyana; ar=akuressa data in a column followed by the same letter are not significantly different by dmrt. all the test lines showed lower germination percentages (gp) when seeds germinated after at 5 days after harvesting (dah), indicating considerable degree of dormancy. 3.3. seeding servival rates survival percentage was highly variable in weedy rice population in ampara and matara districts. ampara population showed highest survival percentage (90%) while lahugala population showed lowest survival percentage (43.33%). except lahugala and mulatiyana populations, other populations showed high survival rates (figure 2). 72 figure 2: survival percentage of weedy rice populations collected from ampara and matara districts. vertical bars on the columns showed standed errors. 3.4. burial test both weedy rice and improved rice varieties showed more than 85% viability and more than 80% germination before burying. the difference between viability and germination of weedy rice was low, inferring that the degree of seed dormancy of weedy rice was not considerable between two locations tested. germination percentage of improved rice buried at 15 cm and 30 cm depth was 45% and 50% respectively at 4wab and it declined sharply to zero at 16wab (figure 3a). the same pattern of results followed a similar pattern for the two improved rice varieties. germination percentage of weedy rice buried at 15 cm and 30 cm depth was 60% and 70% respectively at 4wab and it declined gradually to 32% and 35% respectively at 24wab. viability percentages also followed similar pattern (figure 3b) for improved and weedy rice seeds buried at 15 cm and 30 cm depth. these experiments revealed that weedy rice seeds could remain viable under soil for more than 24 weeks compared with the improved rice varieties, which did not remain viable beyond 16 wab. viability and germination ability of seeds always higher in deep soil (30 cm) compared with surface soil (15 cm depth) for both weedy and improved rice (figures 3 and 4). these results supported the observations of the persistent nature of weedy rice. further, the findings highlight the importance of management measures to decrease the weedy rice soil seed bank of infested fields and of long-term strategies to minimize the soil seed bank of weedy rice. 0 10 20 30 40 50 60 70 80 90 100 s u rv iv a l p e rc e n ta g e population ratnasekera & rupasingha /journal of tropical forestry and environment vol. 5. no 02 (2015) 67-75 73 (a) (b) weedy rice seeds at 15 cm depth weedy rice seeds at 30 cm depth improved (at 362) seeds at 15 cm depth improved (bg 359) seeds at 30 cm depth figure 3: germination and viability percentage of improved rice and weedy rice seeds from 4 to 24 weeks after burying in paddy soil. figure 4: comparison of seed viability in weedy and improved rice at two different depths (15 cm &30 cm) at 12 wab by using ttc test. 4. discussion constantin (1960) reported three types of red rice based on hull colour. further, straw hull red rice is more common than black hull (huey and baldwin, 1978; smith, 1981). presence of awn in seeds was a characteristic feature to weedy rice, but occurrence of awn less seeds also in a considerable percentage (>35%) in the all populations was noticed. similarly, perera et al. (2010) reported that higher variation in weedy rice seeds among and within the locations of amapara district, and reported 4 categories of awn types, which has been supported by the observation by marambe and amarasinghe, in 2000. 0 10 20 30 40 50 60 70 80 90 4 6 8 10 12 14 16 18 20 22 24 s e e d v ia b il it y ( % ) weeks after burial weedy rice (15 cm depth) weedy rice (30 cm depth) cultivated rice (15 cm depth) cultivated rice (30 cm depth) 0 10 20 30 40 50 60 70 80 2 4 6 8 10 12 14 16 18 20 22 24 s e e d v ia b il it y ( % ) weeks after burial weedy rice (15 cm depth) weedy rice (30 cm depth) cultivated rice (15 cm depth) cultivated rice (30 cm depth) 74 our study clearly indicated that prolong longevity (more than 24 weeks) and viability of weedy rice seeds in field conditions implying their key role as a weed by enriching soil seed bank. one previous study found that certain weedy rice populations from temperate rice planting regions have either extremely weak or no seed dormancy (delouche et al., 2007). xia et al. (2011) confirmed that weedy rice in temperate rice planting regions evolved directly from domesticated rice and have weak or no dormancy. by contrast, the seed dormancy of tropical weedy rice may be attributable to a hybrid ancestry involving a wild species that donated genes for dormancy (veasey et al., 2004). in addition, morphological diversity, not only among the weedy rice populations but also within them, offers an array of traits that could be studied and incorporated to future rice-breeding programs (griselda et al., 2004). previous studies have reported that diversity of seed traits such as hull colour in weedy rice is greater than cultivated rice (fogliatto et al., 2011). our results showed that great diversity in weedy rice seeds and the favourable characteristics such as high germination percentage, high survival ability, awn less seeds, proper seed shape and pericarp colour can be incorporated into cultivated rice varieties in rice breeding programs. in particular, the awned populations showed the greater diversity in traits that can impact species’ weediness (fogliatto et al., 2011). we found large variability in germination pattern characteristics known to influence seed bank dynamics and infestation evolution. from an evolutionary point of view, awned populations would be favoured under different environmental and cropping systems, being able to adapt more easily. according to this study, awned populations are usually dormant and influence weedy rice population dynamics and eventually the competitiveness of this weed. therefore, management practices have essentially to take them into account and be adapted accordingly. our study also inferred that the morphophysiological variation of the weedy rice seed populations was not associated with the agro-ecological conditions; for example, the dry and the wet zone. this is probably caused by seed-mediated gene flow via farmers’ frequent exchange of rice cultivar seeds and through other media such as the machinery used for rice harvesting and water canals. acknowledgement authors wish to acknowledge the financial support from the transforming university of ruhuna to international status (turis) 2011 project for this experiment. references abeysekara, a.s.k., herath, h.m.s., wickrame, u.b., nugaliyadde, l. and johnson, d.e. 2010. germinability, viability, and longevity of weedy and cultivated rice in sri lanka. int. rice research conference, 2010, hanoi, vietnam. arrieta-espinoza, g., sanchez, e., vargas, s., lobo, j., quesada, t. and espinoza, a.m. 2005. the weedy rice complex in costa rica: morphological study of relationships between commercial rice varieties, wild oryza relatives and weedy types. genet. resour. crop ev. 52, 575-587. cao, q.j., lu, b.r., xia, h., rong, j., sala, f., spada, a. and grassi, f. 2006. genetic diversity and origin of weedy rice (oryza sativa f. spontanea) populations found in north-eastern china revealed by simple sequence repeat (ssr) markers. annals of botany. 98(6): 1241-1252. chang, s.o., yong, h.c., seung, j.l., dong, b.y., huhn, p.m. and sang, n.a. 2004. mapping of quantitative trait loci for cold tolerance in weedy rice. breed. sci. 54: 373-380. constantin, m.j. 1960. characteristics of red rice in louisiana. phd thesis, agriculture and mechanical college, louisiana state university, la. delouche, j.c., burgos, n.r., gealy, d.r., de san martin, g.z. and labrada, r. 2007. weedy rice: origin, biology, ecology and control. food and agriculture organisation, rome, italy. ratnasekera & rupasingha /journal of tropical forestry and environment vol. 5. no 02 (2015) 67-75 75 fogliatto, s., vidotto, f. and ferrero, a. 2010. effects of winter flooding on weedy rice (oryza sativa l.) journal of crop protection. 29:1232-1240. fogliatto s, vidotto f, ferrero a., 2011. morphological characterisation of italian weedy rice (oryza sativa) populations. weed res.52: 60-69. he, z., jiang, x., ratnasekera, d., grassi, f., perera, u. and lu, b-r. 2014. seed mediated gene flow promotes withinpopulation genetic variation of weedy rice: implication for weed management. public library of science one 9(12): e112778. heu, m.h., cho, y.c. and suh, h.s. 1990. cross affinity of korean weedy rice to the cultivars, korean journal of crop science. 35: 233-238. huey, b.a. and baldwin, f.l. 1978. red rice control. in e.f. eastin (ed.) red rice: research and control. texas agric. exp. stn. bull.b-1270, 19-25 pp. jiang, h., wu, j.l. and wang, g.l. 1985. studies on ludao of lianyungang, crop genet. res.2: 4-7. labrada, r. 2010. weedy rice problems and solutions for its management. international rice commission newsletter, 55: 114-118. ma, d.r., wang, n., wang, y., jia, d.t. and chen, w.f. 2008. germination dynamics of weedy rice in northern china at different sowing depths, chin. j. rice sci. 22:215-218 (in chinese). maguire, j.d. 1962. speed of germination-aid in selection and evaluation for seedling emergence and vigor. crop sci. 2:176-177 marambe, b. and amarasinghe, l. 2000. weedy rice in sri lanka. in wild and weedy rice in rice ecosystems in asia-a review.(eds. b.b. baki, d.v chin, a.m. mortimer), international rice research institute, philippines:79-82 michael, r., thurber, c.s., gross, b.l., olsen, k.m., jia, y. and caicedo, a.l. 2010. "genomic patterns of nucleotide diversity in divergent populations of u.s. weedy rice" bmc evolutionary biology 10. noda, k., prakongvongs, c. and chaiwiratnukul, l. 1985. topography of the seeds and leaves of tropical weeds – with a scanning electron microscope. national weed science research institute project. 158. perera, u.i.p., ratnasekera, w.a.d.p.r. and senanayake, s.g.j.n. 2010. morphological diversity of weedy rice accessions collected in ampara district. proceedings of the 15 th international forestry and environmental symposium, university of sri jayewardenepura, sri lanka, 190194 pp prathepha, p. 2009. seed morphological traits and genotypic diversity of weedy rice populations found in thai hom mali rice fields of north-eastern thailand. weed biol. manage: 1-9 smith, r.j. jr. 1981. control of red rice (oryza sativa) in water-seeded rice (o. sativa). weed sci. 29:663-666. vaughan, l.k., ottis, b.v. and prazak-havey, a.m. 2001. is all red rice found in commercial rice really oryza sativa? weed sci. 49:468-476. veasey, e.a., karasawa, m.g., santos, p.p., rosa, m.s., manani, r.e. and oliveira, g.c.x. 2004. variation in the loss of seed dormancy during after ripening of wild and cultivated rice species. annals botany, 6: 875-882. xia, h-b., xia, h., ellstrand, n.c., chao yang, c. and lu, b-r. 2011. rapid evolutionary divergence and ecotypic diversification of germination behaviour in weedy rice populations. new phy. 191(4):1119-1127. zainudin, p.m.d.h., azmi, m., ahmad, s. and othman. 2010. morphological study of the relationships between weedy rice accessions (oryza sativa complex) and commercial rice varieties in pulau pinang rice granary area. j. trop. life sci. res. 21(2): 7-40. chapter five: discussion caldera & amarasekera /journal of tropical forestry and environment vol. 5. no 01 (2015) 71-82 71 investigation of sawmill management and technology on waste reduction at selected sawmills in moratuwa, sri lanka h.t.s. caldera * and h.s. amarasekera department of forestry and environmental science, university of sri jayewardenepura, nugegoda, sri lanka date received: 14-07-2014 date accepted: 25-10-2014 abstract the demand for sawn timber and wood-based products is rising steadily with new developments and the growing domestic consumption in sri lanka. therefore, it is important to strike a balance between the increasing demand and consumption of forest resources. thus, the key objective of this study was to investigate the effects of sawmill management and technological parameters on loss in conversion from logs to sawn timber and to compare the sawmill efficiency in private sawmills with the state timber corporation sawmill. sawmill management and technological parameters were studied in 21 private sawmills and state timber corporation sawmill in kaldemulla to evaluate the effects on loss in conversion. the selected sawmills represent all types available in sri lanka, i.e., frame saw, circular saw and band saw mills. based on the results, mean percentage loss in conversion of teak and mahogany timber for all sawmills (private and state timber corporation) in moratuwa found to be 53.10%. significant differences were observed in loss in conversion values between the three categories of private sawmills as well as within sawmills of the same category. it was shown that loss in conversion values also varied with sawmill management and technological parameters such as type of machinery employed, sharpening frequency and sawyer’s experience, saw setting, availability of log alignment equipment and saw guards, oversizing and sawn timber sizes. keywords: sawmill, loss in conversion, waste reduction, mahogany, teak 1. introduction forests covered over four billion hectares of land or 30% of the earth’s land surface globally. in 2005, 3.5 billion m 3 of wood of 434 billion m 3 of growing stock were removed from the forests where 60% of this amount was industrial round wood and the rest was fuel wood (kirilenko and sedjo, 2007). north america, asia and western europe, are the key suppliers in contributing for the world wood demand (sandvik, 1999). as a result of natural forests shrinkage and restrictions on felling and transport there is declining trend in the timber supply from natural forests in sri lanka (amarasekara, 1996). despite the * correspondence: savindi.c.@gmail.com tel: +61 451779663 issn 2235-9370 print/issn 2235-9362 online © university of sri jayewardenepura 72 fact that the forest cover is depleting it was forecasted that the demand for sawn wood will grow from 0.544 million m 3 in 1993 to 0.885 million m 3 in 2020, showing an increase of about 12,600 m 3 /year at an average annual growth rate of 2% (fsmp,1995). sawmilling is a primary industry which provides raw materials to other industries such as construction, joinery, furniture and others. sawmills can be categorised according to size, machinery and raw materials requirements (weerawansa and amarasekera, 1997). sawing of logs is an essential requirement to their proper and ultimate use and sawmilling plays a significant role in wood utilisation. substantial amount of total industrial wood products reaches the consumer after sawing (dwivedi, 1977). as there is scarcity of raw materials and the level of technology is low, sri lankan sawmills are categorised as “small” by world standards. there are number of saw types namely bandsaw, frame saw and circular saw used to breakdown logs and cut into desired sizes of sawn timber. the choice of machinery depends on log resources (species, quality, sizes) financial facilities and available technical knowledge (blackwell and walker, 2006). awe (2000) describes that the conversion as a measure of sawmill efficiency and it is defined as the percentage volume of sawn timber that can be cut from a given volume of debarked log. blackwell and walker (2006) stated that green conversion ranges from 40-65% in sawmills cutting for grade, which shows a loss in conversion of 35-60%. when considering the waste in converting logs to timber, there are two types such as saw dust and off cuts (briggs, 1994). it is apparent that there is a major impact on the loss in conversion during log processing due to factors such as type of wood species, the type of machines employed and the skills and the experience of the operators. the effective utilisation of raw materials amalgamated with skilled labour will lead to effective, efficient and profitable sawmilling (lundahl, 2007). nonetheless, the wood waste can be minimised at various points of the log sawing process. if the above factors are taken into account and managed well, sawn wood available to cater the market demand will increase. this will pave the way to reduce the exploitation pressure on the timber resources in sri lanka. the raw material used in sawmills consists of logs which come from different forests which leads to different log characteristics. smith and joe (2006) asserted that the timber yield is affected by several log characteristics such as log diameter, length, taper, eccentricity and sweep. the yield optimisation system can significantly improve timber conversion value in sawmills considering the differences in log characteristics. badejo (1990) emphasised that, the sizes of log being processed, regardless of the species, have important influence on timber recovery. weerawansa and amarasekera (1997) noted that there is high wastage in the sawmill industry in the western province of sri lanka and this research was designed with the purpose of assessing the current situation of the sawmill industry and to conduct a comprehensive study on existing practices on sawmill management and technologies adopted. therefore, the key objective of the study was to investigate the effects of the sawmill management and technological parameters such as different sawmill machinery, milling characteristics, saw doctoring and sawyers’ experience on loss in conversion in sawmills and to compare the sawmill efficiency in private sawmills with the state timber corporation sawmill. caldera & amarasekera /journal of tropical forestry and environment vol. 5. no 01 (2015) 71-82 73 2. methodology 2.1 study site moratuwa area was selected as the study site as it has the highest number of sawmills in the country. moratuwa is popular for its skilled carpentry work and furniture industry, which provides employment opportunities for many people in that area. moratuwa town is located in the colombo district of the western province on the southern direction of city of colombo. it is bounded by dehiwala-mt.lavinia municipal council to the north, indian ocean to the west and bolgoda river to the south and to the east. total extent of the municipal area is approximately 23.4 km 2 . the municipal area is divided into 17 wards (moratuwa municipal council, 2002). there are more than 206 registered sawmills distributed throughout the moratuwa area and 10% of them was selected for the study. 2.2 selection of sawmills stratified random sampling was used to select the samples for the field survey. sawmills were divided into three categories based on the headrig machine (main saw) employed which were considered as stratums. samples were randomly selected from different sawmill categories as shown in table 1. an initial survey was carried out among 45 sawmills in order to decide on the percentage of samples from each category and other related information. a questionnaire was used to interview the sawmill owners and sawmill workers to collect information on sawmill management, technologies utilised, timber species used and to decide on the sampling percentage in the main study. after considering the initial survey results, 21 sawmills were selected for the main study. in addition data were obtained from the state timber corporation sawmill located at kaldemulla to compare the results between government sawmill (stc) and private sawmills. figure 1: study site. 74 table 1: the distribution of samples. type of headrig no. of sawmills sampling% calculated from initial survey frames saw 12 57.14% circular saw 7 33.33% band saw 2 9.52% 2.3 tree species teak (tectona grandis) and mahogany (swietenia macrophylla) were the two types of timber species selected for the study. during sampling, logs with minimum visual defects and less curvature were selected. 2.4 investigation sawmill management under sawmill management several attributes were studied as given in table 2. table 2: qualitative data collected in the study. qualitative data levels skill of sawyer sawyer’s education levelacademic qualifications training-onsite training or national vocational qualifications experience-number of years working in the sawmilling industry as a sawyer saw doctoring type of saw setting done sharpening frequency availability of saw doctoring facility in the sawmill cutting pattern type of cutting pattern (through and through/ cant/ grade/ quarter ) method of log alignment manual or availability of machinery method of log turning manual or availability of machinery sizes sawn by the sawmills different sawn wood products produced and their dimensions consistency of the thickness in the sawn timber and the cutting marks on the surface width measured at different places of sawn timber surface texture (appearancerough/ smooth) 2.5 investigation of sawmill technology the type of machinery used in each sawmill were studied to investigate the level of technology. a variety of saws were used progressively to cut the log into timber of the desired dimensions of sawn timber. the measurements that were taken are given in table 3. instruments such as measuring tape, diameter tape, vernier caliper, ruler and compass were used to collect data. saw blade geometry in circular saws were further measured to assess whether loss in conversion varies with tooth pitch, hook angle, clearance angle and tooth height. caldera & amarasekera /journal of tropical forestry and environment vol. 5. no 01 (2015) 71-82 75 table 3: quantitative data collected in the study. 2.6 calculation of loss in conversion five logs from each species (teak and mahogany) from each sawmill were sampled which accounts to 210 in total. log length and under bark diameter (top, mid and bottom) of each log were measured. extremely large logs and small logs were not considered and logs with considerable external visual defects were not sampled to avoid errors. log volume was calculated using the following formula (newton’s formula) with the values of parameters collected (equation 1). sawn timber produced by the selected 210 logs was measured immediately after sawing and sawn timber volume was calculated using equation 2. loss in conversion of each log was calculated as a percentage by using equation 3 (blackwell & walker, 2006) which will provide an indication of the efficiency of the sawmill operations. ( ) where: l= log length dt= top diameter dm= mid diameter db=bottom diameter ) ) ) 3 data obtained for sawmilling wastage from private sawmills and state timber corporation sawmill were computed for both timber species (teak and mahogany) and for different machines. correlation, regression and mann-whitney-u test were used for advance statistical analysis. furthermore, 1-way-anova was used to test the significance of factors within turkey’s pairwise comparison method. quantitative data levels log dimensions diameter at bottom (cm) diameter at top (cm) diameter at middle (cm) height (m) sawn timber dimensions width (cm) thickness (cm) length (m) saw blade geometry tooth height (cm) tooth pitch (cm) hook angle ( 0 ) milling characteristics oversizing (cm) blade thickness (mm) kerf (mm) 76 3. results 3.1 sawmill management number of sawyers and educational levels results showed that the number of workers employed in sawmills varied from 2 to 7. the main sawyer was responsible to feed the log to the headrig while others assist him in it and do their tasks in edging, cross cutting and other auxiliary processes in sawn timber production. sawyers educational level and training all sawyers interviewed have studied up to grade 8 or gce ordinary level in secondary education and none of the sawyers have pursued up to gce advance level examination. sawyers of the state timber corporation which accounts for 5% of total sawyers received training on sawmilling and saw doctoring from timber technology training institute. all sawyers work in private sawmills did not receive any specific skill training but have undergone onsite training where they have learned through experience. saw setting in sawmills out of the 22 sawmills sampled, 68% used spring setting as the saw setting technique while 32% adopted swage setting. it was observed that the swage-set tooth points have less opportunity of sideways deflection whereas with spring-set teeth have is a gap between one side and the timber. carbide tips were observed in all circular sawmills in moratuwa where they adopted swage setting. log turning, log alignment and cutting pattern log turning and log alignment in all sawmills were manually done and hence the productivity of these operations depend on the proficiency of the sawyer in terms of knowledge and skill in checking for wood defects and deciding cutting patterns to produce maximum volume of sawn timber. it was observed that the main sawyer is responsible for feeding the log into the headrig where some of them have developed that skill of log alignment, checking for the “crack directions from the pith” and feed the log perpendicular to that to minimise the effects of the crack in the sawn timber. all sawmills followed the through and through cutting pattern which is frequently used for sawing planks. log storage, sawmill housekeeping and utilisation of wood waste most sawmills stored logs in an adjacent land to sawmill. however, there were no special measures taken to protect logs in the log yard. green logs and sawn timber were just laid on the ground without proper stacking and was exposed to insects, fungi and weather changes. poor housekeeping was observed in sawmills as sawdust and wood parts were lying haphazardly. 18 sawmills sell the collected sawdust and off cuts to buyers who use them for boilers, to manufacture briquettes and off cuts to produce small furniture such as toys and for wood composite industry. stc sawmill provide some amount of sawdust for free of charge to local community to use as fuel. the rest of sawmills dispose the sawdust to a dump yard or nearby water source close by creating environmental issues. 3.2 milling characteristics the mean diameter in middle of the mahogany log sample (105 logs) was 34.5 cm and the mean mid diameter of the teak log sample (105 logs) was 34.2 cm and the mean log length of the 210 logs was 3.3 m. through the interview, it was revealed that sawmills produce oversized timber accommodating planning allowance and shrinkage allowance. results showed that 62% of sawmills use oversizing of (0.32 cm while a 4% of sawmills use an oversizing of (0.48 cm . caldera & amarasekera /journal of tropical forestry and environment vol. 5. no 01 (2015) 71-82 77 diameter and length of timber species sampled from private sawmills figure 1 illustrates the relationship between log length and loss in conversion. the line shows an increasing trend with the increase in log length. there was a significant correlation between these two variables. figure 2 shows the relationship between log mid diameter and loss in conversion which shows a decreasing trend with the increase in mid diameter of logs. the correlation between these two variables was significant. figure 2: variation of loss in conversion with the mid diameter of logs. 3.3 loss in conversion in private sawmills mean percentage loss in conversion of private sawmills in moratuwa was 56.9% (conversion of 43.1%). the highest average loss in conversion value was observed in inserted tooth circular sawmill. the lowest average loss in conversion was showed in band sawmill. the effects of various factors on loss in conversion are described in the following section. mid diameter (cm) l o s s i n c o n v e r s io n % 5550454035302520 75 70 65 60 55 50 45 40 figure 1: variation of loss in conversion with log length. log length(m) l o s s i n c o n v e r s io n 87654321 0.75 0.70 0.65 0.60 0.55 0.50 0.45 0.40 78 effect of the type of machinery and timber species on loss in conversion the results in table 5 showed the mean loss in conversion% values. the highest mean loss in conversion was shown in the inserted tooth circular saw for mahogany and teak recorded mean loss in conversion values of 65.05% and 63.77% respectively. the lowest mean loss in conversion was shown when timber was sawn by band saw which was 45.19% and 46.75% for mahogany and teak respectively. table 5: results of anova test carried out for mean loss in conversion between sawmill type and timber species. one-way anova tests conducted between sawmill types for mahogany timber species indicated significant results (table 6). this indicated a significant difference between loss in conversion values of band, circular and frame saw when sawing mahogany. similarly the results were significant for teak as well. this indicates that the sawmill technology or the machinery deployed have caused a variation of loss in conversion. table 6: results of anova test carried out for mean loss in conversion within sawmill type. timber type sawmill type p value significance teak frame saw 0.000 significant circular saw 0.004 significant band saw 0.029 significant mahogany frame saw 0.000 significant circular saw 0.004 significant band saw 0.029 significant table 7 shows the mean loss in conversion values of private and stc sawmills which used a bandsaw for headrig. mean loss in conversion values of mahogany and teak species were lower in private sawmills when compared to stc sawmill. mean loss in conversion value of teak in stc was higher than that of private sawmills as stc remains the sapwood while private sawmills utilise it. however, mann-whitney u test did not show significant difference between the mean loss in conversion values between stc sawmill and private band sawmills. machine/ species mahogany % teak % mean loss in conversion % band 45.19 46.75 45.97 circular 65.05 63.77 64.41 frame 54.03 54.66 54.34 species private sawmills% stc sawmill% mahogany 45.88 (sd=0.31) 46.74 (sd=0.03) teak 42.35 (sd=0.14) 52.04 (sd=0.08) table 7: mean loss in conversion of private sawmills and stc. caldera & amarasekera /journal of tropical forestry and environment vol. 5. no 01 (2015) 71-82 79 effect of blade thickness on loss in conversion figure 3 illustrates the variation of loss in conversion with the blade thickness. the highest mean loss in conversion was observed when the blade thickness was 4.19 mm whilst the lowest mean loss in conversion value was observed when the blade thickness was 1.24 mm. mean loss in conversion increased with the increase in blade thickness. it can be observed that the blade thickness varied in the different machineries which caused variation of loss in conversion. a significant correlation also proved the effect of blade thickness in loss of conversion. blade thickness (mm) m e a n l o s s i n c o n v e rs io n % 4.03.53.02.52.01.51.0 70 65 60 55 50 45 40 saw ty pe band c ircular frame figure 3: variation of mean loss in conversion for different blade thickness. effect of kerf on loss in conversion figure 4 illustrates the variation of loss in conversion with kerf which is a parameter measured under milling characteristics. mean loss in conversion increased with the increase in kerf. the highest mean loss in conversion was observed when the kerf was 4.50 mm whilst the lowest mean loss in conversion value was observed when the kerf was 2.2 mm. therefore, if the kerf is low a lower loss in conversion is occurred. kerf (mm) m e a n l o s s i n c o n v e rs io n % 5.04.54.03.53.02.52.0 70 65 60 55 50 45 40 saw ty pe band c ircular frame effect of circular saw geometry on loss in conversion a positive correlation was observed between tooth height and loss in conversion whereas a negative correlation was shown between the hook angle and the tooth pitch and the loss in conversion figure 4: variation of mean loss in conversion with different kerf. 80 (table 8). when the tooth height increases further after a certain level it generates more saw dust during cutting and increases the loss in conversion as the gullet area gets expanded. table 8: inserted tooth circular saw geometry. e y ’ xp figure 5 showed the variation of mean loss in conversion with the sawyer’s experience in number of years. there is a decreasing trend of mean loss in conversion with the increase sawyer’s experience. figure 5: variation of loss in conversion with sawyer’s experience. 4. discussion the present study was based on assessing effects of sawmill management and technological parameters on loss in conversion, which provides an indication on the level of sawmill efficiency. the calculations were carried out using the method described by blackwell and walker (2006) taking log volume and sawn timber volume into consideration. based on the results, the average percentage loss in conversion of teak and mahogany timber for all sawmills (private and stc) in moratuwa is 53.10% (conversion 46.9%) which is within the green conversion range of 40-65% in sawmills cutting for grade suggested by blackwell and walker (2006). 0 10 20 30 40 50 60 70 80 0 5 10 15 20 25 30 m e a n l o ss i n c o n v e r si o n % main sawyer's experience in years sawmill tooth pitch (cm) hook angle ( o ) tooth height (cm) mean loss in conversion % c1 7.3 30 5.7 63.46 c2 9.5 35 4.1 62.13 c3 7.2 30 5.9 66.80 c4 7.8 30 6.2 66.26 c5 9.4 35 4.0 61.86 c6 7.5 30 6.0 66.57 caldera & amarasekera /journal of tropical forestry and environment vol. 5. no 01 (2015) 71-82 81 loss in conversion values between the three sawmill categories varied at a statistically significant level. under the private sawmills the highest wastage was observed in inserted tooth circular saw which recorded a mean loss in conversion value of 64.4%. this can be caused by using thick tungsten carbide tipped blades used in those sawmills. weerawansa and amarasekera (1997) stated the most wasteful machine was inserted tooth circular saw which was proved in the current study as well. the difference in gauge of the carbide tips can also cause the variation of the saw dust generated and the volume of the solid wood waste (slabs) produced. as saw guards were unavailable in most circular sawmills, it led to disorient the log as the machine vibrates and results in crooked cuts and inconsistent planks. moreover the surface texture is irregular and rough when timber is sawn using inserted tooth circular saw. percentage loss in conversion values were relatively low in frame saw and band saw which were 54.3% and 46.0% respectively. the lowest loss in conversion showed in band sawmills can be attributed to thin flexible cutting blades employed in those mills. steele (1984) also showed that band sawing which use a thinner blade cut drastically changes the yield. a high loss in conversion can be caused by to circular saw machine deployed, lack of experienced sawyers, poor skills in log turning and log alignment, excess oversizing and poor saw doctoring. in converse the lowest mean loss in conversion in band sawmills can be attributed to band saw machine used, experienced sawyers and effective sawmill management. for the variation in loss in conversion values within the same sawmill category can be attributed to sawyer’s level of education, training, experience, the state of saw doctoring (saw sharpening and maintenance), skill in log alignment and log turning, and milling characteristics such as oversizing, product sizes sawn and kerf. the difference in gauge (blade thickness) of the carbide tips in inserted tooth circular saw and the variation in blade thickness of frame and band saw can also cause the deviation of the saw dust generated and the volume of the solid wood waste (slabs) produced in sawmills with in the same category. the results show that the loss in conversion increased with the increased blade thickness and kerf. kukogho et al (2011) also found saw kerf is directly proportional to the volume of sawdust produced during sawing. results revealed that band saws have thinner blade thickness and kerf compared to circular saw. bratkovich (1996) also stated when circular saws are compared to band saws, then band saws would be considered higher gauge (lower blade thickness). it was observed that when the hook angle increases and the tooth it has a tendency to wear off and break. tooth geometry is subject to a number of interactions. walker (2006) also states that increasing the hook angle and reducing the sharpness of tooth will affect the tooth to wear faster and is more likely to break. according to the primary log data gathered, some logs with similar dimensions had different loss in conversion values, which could be attributed to the grade of the timber. grade is assessed by the nature and number log defects which reflects the quality of the timber. therefore the timber grade has an impact on the recovery of the sawn timber. 5. conclusion it was shown that loss in conversion values varied with sawmill management and technological parameters such as type of machinery employed, sharpening frequency and sawyer’s experience. furthermore loss in conversion can be affected by saw setting, availability of log alignment equipment and saw guards, oversizing and sawn timber sizes as well. therefore, the loss in conversion in sawmilling is determined by an interaction of several factors. 82 the results depicted that the blade thickness significantly affect the loss in conversion value. high wastage was caused by using thick tungsten carbide tipped blades used these saw sawmills. in contrast lowest loss in conversion was showed in band sawmills with thin flexible cutting blades. it is important to replace obsolete machinery with new technology to reduce wood waste in form of sawdust. upgrading of machinery can be done by means of using thin kerf saws and hence band saw can be recommended. in order to saw denser species band saws with tungsten carbide tips can be proposed. through the interviews it was revealed that there is an issue of metal wires and particles inside the logs hindering the functioning of the saw, a metal detector or a scanning device will be conducive for detecting the presence of metal parts in the log. references amarasekara, h. 1996. selecting alternatives in place of naturally grown timber species. local timbers for future, 49-52. awe, o.a. 2000. assessment of wood conversion efficiency in some sawmills in ondo state, unpublished nd project, federal college of forestry, jericho, ibadan. badejo, s.o. 1990. sawdust utilization for building material manufacturing in nigeria, technical report, forestry research institute of nigeria, ibadan, january, 2001. blackwell, p. and walker, j.c. 2006.sawmilling in primary wood processing. springer, netherlands. bratkovich, s. 1996. thin kerf sawing: a technology worth adopting, usda forest service, northeastern area state & private forestry. briggs, d.g. 1994. forest products measurements and conversion factors: with special emphasis on the us pacific northwest. college of forest resources, university of washington, seattle. dwivedi, a. 1977.handbook of saw milling. fsmp. 1995. forestry sector master plan, forest resources development division, ministry of agriculture, lands and forestry. kirilenko, a.p. and sedjo, r.a. 2007. climate change impacts on forestry. proceedings of the national academy of sciences, 104(50): 19697-19702. kukogho, j., aghimien, e., ojo, m., adams, b. and akinbosoye, b. 2011. assessment of wood waste generated in some selected sawmills in kajola local government area of oyo state. continental journal of agricultural economics, 5(2). lundahl, c.g. (2007). optimized processes in sawmills: luleå tekniska universitet/ltu skellefteå/träteknologi. moratuwa municipal council, 2002.city profile, http://www.unhabiat.lkdownload/scp/moratuwa.pdf. sandvik, a.b. 1999. the handbook of production use and maintainace of wood bandsaw blades. sandvik coromant, sweden. smith, a.j. and joe, b. 2006.factorsdetermining lumber recovery in sawmilling. national board of vocational education, forestry training programme for developing countries, helsinki, finland. steele, p.h. (1984). factors determining lumber recovery in sawmilling. retrieved from http://oai.dtic.mil/oai/oai?verb=getrecord&metadataprefix=html&identifier=ada142080 walker, j.c. (2006). primary wood processing: principles and practice. springer science and business media. weerawansa, p.s. and amarasekera, h.s. 1997. evaluation of the sawmilling wastage of sawmills in western province of sri lanka, proceedings of the 3 rd annual forestry symposium of the department of forestry and environmental science, university of sri jayewardenepura, sri lanka. http://www.unhabiat.lkdownload/scp/moratuwa.pdf 62 impact of land use changes on soil properties and organic carbon distribution using tracer techniques in selangor state of malaysia m.b. hossain1*, k. jusoh2 and s. fatimah2 1soil science division, bangladesh institute of nuclear agriculture (bina), bau campus, mymensingh, bangladesh 2school of environmental and natural resource sciences, faculty of science and technology, university kebangsaan malaysia, bangi, selangor, malaysia date received:21-09-2017 date accepted: 23-12-2017 abstract root and litter biomass on carbon dynamics and its effect on other soil properties information are needed to explore in malaysia due to rapid change of land use.objective of this study was to determine the effect of root and litter biomass of forest and oil palmunder different soil depths on soil organic carbon and its stock,soil available water, bulk density, ph, electrical conductivity. in this regard, twoland use systems (forest and oil palm) were selected for the study. in each land use we collected litter biomass, root and soil samples from four different locations. for the characterization of soil and root three core samples were taken (0-5, 5-15, 15-30, 30-60 and 60-90 cm)from each location, and then combined and air-dried.soil samples were air-dried for 2 weeks at room temperature, grounded and sieved (<2 mm). soil available water content, soil organic carbon, ph and ec were determined by standard methods.results revealed that maximum organic matter (6.75%) was found in forest soil at 0-5 cm depth of soil. soc content was decreased with the increase of soil depth in forest. on average soil organic carbon stock was significantly higher under oil palm (3.09 t ha-1) than forest (2.28 t ha-1) up to 90 cm depth of soil. available water content was higher in surface soil (0-15 cm) than subsurface soil due to mechanization of oil palm plantation area. soil reaction (ph) was higher in forest soil than oil palm plantation soil.litter biomass or droppings performed δ13c dilution in surface soilbut root system enriched δ13c in subsurface soil. 13c isotope tracer technique confirmed that root and litter biomass of forest and oil palm plantation can greatly influence on vertical distribution of organic carbon when soils show gradual increase of δ13c values with depth. keywords: land use,forest and oil palm,soil depth,carbon,tracer techniques 1. introduction land-use changes in tropical ecosystem lead to major modifications of soil properties and processes. in 2012 malaysia had 5.08 million hectares of oil palm plantation. over the year’s oil palm plantation keep increasing since 2008 by 11.8% and contributed 39% of the world's total palm oil production (board, 2012). a rapid change of land use from natural forest to plantation agriculture inmalaysia is increased due to attain sufficiency for food, oil, and biofuels (fargione et al., 2008; gibbs et al., 2008; kurniawan, 2016). specially land use affects soc stock, co2 exchange and soil physicalchemical properties.several investigators have reported a net loss of soc (kotowska et al., 2015). conversely, others had reported that the conversion to oil palm plantations led to a net gain of soil c stock (flynn et al., 2012; frazao et al., 2013; patthanaissaranukool and polprasert, 2011; siangjaeo et al., 2011).land use changes can perform a great variation on litter biomassto soil surface and plant root hossain et al. /journal of tropical forestry and environment vol. 7, no. 02 (2017) 62-70 63 density in soil(laganiere et al., 2010). in accordance with the knowledge of authors, information about the effect of biomass distribution and root systemsin forest and oil palm plantation on carbon distribution and other soil propertiesis generally scarce in selangor state of malaysia.plant functional types significantly affected the vertical distribution of soc.carbon isotope tracer technique was also used to confirm the source of carbon stored in forest and oil palm soils because decomposition of soc directly effects its isotopic composition. the present investigation was planned to examine the effect of litter biomass and plant roots of forest and oil palm plants on vertical distribution and source of soil organic carbon using 13c tracer technique and also to evaluate the impact of land use changes in soil available water, bulk density, ph and electrical conductivity. 2. materials and methods 2.1 study site two land uses namely tropical forest and oil palm plantation located at bangi in selangor state, malaysia were selected for the study (figure 1).oil palm plantationis of 37 years old at university putra malaysia (upm). figure 1:map showing the locations of the study areas (forest area:university kebangsaan malaysia (ukm), oil palm area: university putra malaysia (upm) in selangor state of malaysia. the university kebangsaan malaysia (ukm) permanent forest reserve is an area within the main campus of ukm in bangi, developed in an area formerly known as bangi forest reserve (bfr).the bangi forest reserve (bfr) lies between 2° 54' and 101° 4.5' e in the district of rulu langat, selangor darul ehsan, some 35 km south of kuala lumpur.this quartzite soft rock-based forest is bordered by the langat river in the north and kuala lumpur-seremban highway in the south. topographically the area is moderately flat with several small streams and patches of swamps, at altitude of 40 m to 110 m above sea level. 64 2.2 sampling and analysis experiment was carried out from june to december; 2016.two land use systems (forest and oil palm) were selected for the study. figure2: oil palm root at different depths of soil. in each land use we collected litter biomass, root and soil samples from four different locations. for the characterization of soil and root three core samples were taken (0-5, 5-15, 15-30, 30-60 and 6090 cm) from each location (figure 2). three soil core samples from each depth were mixed in homogenously to make composite sample.then the samples were dried, grinded and sieved with a <2.0mmsieve and stored. litter biomass was collected from 1.0 m2 area and it converted in g/0.10 m2. amount of root was estimated from different soil profiles in respect of their depth. depth-wise soil sampleswere collected using a metal core sampler for bulk density analysis (blake and hartage, 1986). soil ph (soil:water 1:2.5) and electrical conductivity (ec) was determined by following standard methods (jackson, 1967).available water contents were determined using ceramic plates (townend et al., 2001). 2.3 soil organic carbon stock calculation organic carbon stock results were estimated using the total forest and oil palm plantation areas (18,270,000 and 222,778 ha) (mspo, 2015; nre, 2016), respectively. the size of the total c stock is calculated following the method as described by batjes (1996). it involves calculation of soil organic carbon (soc) bymultiplying the proportion of organic carbon in a given site by bulk density and the thickness of the horizon for individual soil sample with different thicknesses varying from 0–5, 5-15, 1530, 30-60 and 60-90 cm. the total soc stock was calculated using this formula. soc stock in soil =bd × corg × d × a (1) where: bd = bulk density of soil (g cm−3) corg = mass concentration of organic carbon (%) in soil d = depth of soil (cm) a = area of land covered by forest and oil palm and lastly socstock converted in t ha−1. isotopic composition is expressed in δ notation (in %) rsample hossain et al. /journal of tropical forestry and environment vol. 7, no. 02 (2017) 62-70 65 δ(‰) = [-------------------1] × 1000 (2) rstandard where: r = molar ratio of heavy to light isotope of the sample or the international pdb reference. accordingly, 13c enrichment leads to less negative δ13c values. in natural systems, kinetic fractionation leads to a substrate 13c enrichment.appropriate statistical analyses were performed with the mean data of each parameter. mean differences of different parameters were tested by analysis of variance (gomez and gomez, 1984; table 1) except litter biomass and its organic carbon content. standard deviation was used for litter biomass and its organic carbon. 3. results to determine the contribution of plant roots and litter biomass onsoil organic carbon (soc), we analysed the mean root dry weight and litter biomass fresh and dry weight values up to 90 cm i.e. five depths of soil profile (figure3a,b & c). figure3: mean root dry weight (a), root organic carbon at different land use with soil depth and fresh, dry weight of biomass of litter and organic carbon content (c) on surface soil. the mean root dry weight value (mean value of five soil depth profile) was higher under oil palm plantation (1.94 g) than under forest (0.31 g) except 0-5 cm depth of soil (figure 3a). maximum root dry 0.00 0.50 1.00 1.50 2.00 2.50 3.00 3.50 0-5 5-15 15-30 30-60 60-90 r o o t w t. ( g ) soil depth (cm) a forest root oil palm root 0 10 20 30 40 50 0-5 5-15 15-30 30-60 60-90 o rg a n ic c a rb o n in r o o t (% ) soil depth (cm) b forest soil oil palm soil 98.64±82.1 3 38.78±50.8 3 4 1 .9 3 ± 8 .7 7 150.29±31 .89 86.76±14.3 6 4 2 .8 7 ± 4 .9 7 0 20 40 60 80 100 120 140 160 fresh wt dry wt %oc b io m a ss w t. ( g /0 .1 m 2 ), a n d o c c o n te n t (% ) biomass of litter c oil palm 66 weight was obtained from 30-60 cm soil depth and the minimum root dry weight was found in 60-90 cm depth of soil in forest area. root organic carbon content results are presented (figure3b).higher root organic carbon was found in oil palm plantation soil than forest soil. maximum organic carbon content was observed in 5-15 cm depth of soil both in oil palm and forest soil. litter biomass as well as organic carbon content results are presented (figure3c).maximum fresh and dry weights of surface residue were obtained from forest area and minimum fresh and dry weights of residue were found in oil palm plantation area. little bit higher organic carbon was found in forest residue. more or less similar trend organic carbon content was observed in forest and oil palm plantation. the effects of soil depth and land use on organic matter and its stock, available water, bulk density, ph and ec results are presented (figure4a, b, c, d, e & f). figure4: mean soil organic matter (a), soil carbon stock (b), available water (c), bulk density (d), ph (e) and ec (f) at different land use with soil depth. organic matter in forest soils was higher at 0-5 cm depth than oil palm soil (figure 4a). in forest soil, organic matter decreased with the increase of soil depth except 15-30 cm depth. maximum soil organic matter (6.75%) was found in forest soil at 0-5 cm depth. inconsistent results of organic matter were found in oil palm plantation soil. maximum organic matter was found in 15-30 cm depth of oil palm soil. on average, organic matter increased (5%) in oil palm plantation over forest soil.organic carbon 0 2 4 6 8 0-5 5-15 15-30 30-60 60-90 o rg a n ic m a tt e r (% ) soil depth (cm) a forest soil oil palm soil 0.0 1.0 2.0 3.0 4.0 5.0 6.0 0-5 5-15 15-30 30-60 60-90 o rg a n ic c a rb o n s to ck ( t h a -1 ) soil depth (cm) b forest soil palm oil soil 0.00 0.40 0.80 1.20 1.60 2.00 2.40 0-5 5-15 15-30 30-60 60-90 a v a il a b le w a te r (c m 3 cm -3 ) soil depth (cm) c forest soil 0.00 0.50 1.00 1.50 2.00 0-5 5-15.0 15-30 30-60 60-90 b u lk d e n si ty ( g c m -3 ) soil depth (cm) d forest oil palm 0.00 0.50 1.00 1.50 2.00 2.50 3.00 0-5 5-15 15-30 30-60 60-90 e c ( d s -1 ) soil depth (cm) f forest soil oil palm soil 4.2 4.4 4.6 4.8 5.0 5.2 5.4 0-5 5-15 15-30 30-60 60-90 p h soil depth (cm) e forest soil oil palm soil hossain et al. /journal of tropical forestry and environment vol. 7, no. 02 (2017) 62-70 67 stock, significant variation was found in different land use with soil depth (figure 4b). maximum organic carbon stock was found in 30-60 cm depth in oil palm soil. organic carbon stock was higher in oil palm soil than forest soil in different depth of soil except 0-5 cm depth.available water content results in forest and oil palm soil are presented (figure4c).higher available water was also observed at lower soil depths in forest area.on the other hand, higher available water contain was found in 0-15 cm depthin oil palm soil but there after it was decreased up to 90 cm soil depth.soil bulk density (bd) results for the two land use types at different soil depths are shown in figure 4d. bd in forest soils was lower at 0-5 and 5-15 cm depths than oil palm soil and the latter depths bd were higherin forest soil than oil palm soil.soil bd was decreased with the increase of soil depth in oil palm plantation but the opposite results were found in forest soil. figure4e shows the results of soil ph for forest and oil palm plantation.there were significant differences in forest and oil palm plantation systems.soil ph for oil palm plantation was significantly lower than for forest soil. the ph value increased with the increase in different depths of forest soil but the inconsistent results were found in oil palm plantation in respect of soil depth.the ranged of ph 4.94 5.27 in forest soil. maximum ph (4.96) was found in 30-60 cm depth of oil palm soil.therefore high som in soils lowers soil ph.electrical conductivity (ec) results are shown (figure4f).ph results increased with the decreased of electrical conductivity. the δ13c distribution results with depth in soils of forest and oil palm plantation are presented (figure5).the δ13c values in different depths of soil in forest were higher than oil palm plantation. the δ13c values, however, were similar in 5-15 cm depth of soil both forest and oil palm plantation. figure5: impact of forest conversion by oil palm plantation on δ13c distributions in different land use with soil depth. the lowest δ13c distribution value was found in 60-90 cm depth of soil. δ13c distribution values were more or less similar trend in oil palm plantation soil. at 60-90 cm soil depth, δ13c values were higher in forest soil than oil palm plantation soil. oil palm plantation soil contained more root biomass than forest biomass. mean square of soil and vegetation of different land use systems are presented (table 1). table 1:mean square of soil properties and vegetation in different land uses of malaysia. source of variation df organic matter organic carbon in residues ph ec forest palm forest palm forest palm fores palm -35 -30 -25 -20 -15 -10 -5 0 0-5 5-15 15-30 30-60 60-90 δ 1 3 c v a lu e depth of soil (cm) forest soil palm soil 68 t soil depth 4 23.05ns 1.82ns 98.27ns 115.7ns 0.08** 0.01ns 0.09* 0.06ns error 12 7.82 2.84 79.59 231.70 31.41 79.59 0.02 0.04 source of variation df soil water dry root wt. bulk density carbon stock forest palm forest palm forest palm forest palm soil depth 4 0.02ns 2.65** 0.16** 4.14ns 0.13** 0.05** 1.11** 11.52* * error 12 0.02 0.06 0.02 5.69 0.01 0.02 0.15 0.14 4. discussion 4.1 soil organic matter maximum organic matter (6.75%) was found in forest soil at 0-5 cm depth. this is because the litter biomass of forest land is not removed by man and animal those contribute organic carbon from their droppings. maximum organic matter was found in 15-30 cm depth of oil palm soil. on average, organic matter increased (5%) in oil palm plantation over forest soil. this can be due to higher amount of root as well as organic carbon content in oil palm soil. the contribution of root inputs to organic c can greatly influence both the total amount and vertical distribution of soc in different depth of soil (oelbermann and voroney, 2007; rumpel and kogel-knabner, 2011).similar findings were reported by keen et al. (2011). conversion to oil palm plantation led to a net gain of soil c stock (flynn et al., 2012; frazao et al., 2013; patthanaissaranukool and polprasert, 2011; siangjaeo et al., 2011) due to suitable land management systems (adugna and abegaz, 2016; six et al. 2002). land use change can lead to an alteration of the amounts and qualities of som (coleman et al., 1989) and can potentially either release or sequester soil carbon (mendham et al., 2003). rasse et al. (2005) also reported that the incorporation of c into the soil was much greater due to plant roots than due to aboveground litter. this information are strongly supported to our findings. 4.2 soil bulk density, ph and ec higher soil bulk densities in the forest soil may have enhanced the soil’s ability to retain water. higher soil bulk densities were found in 5-15 cm depth of soil due to mechanization in oil palm plantation soil. these phenomena may hinder the permeability of water from surface soil to subsurface soil. yahya et al. (2010) reported that the effect of mechanization increased the bulk density of oil palm plantation soil. they also reported that soil bd was affected by the compaction only within the first 0-10 cm depth and there after it was not affected by the mechanization. this information on the effect of land use changes are supported to our research findings. intercultural operations and fertilizer management performed the decline of soil ph in oil palm area. organic and inorganic acids are formed from the decomposed som. these can reduce the soil ph due to soil organic matter (som) is low in base forming cations (brady and weil, 1996). ec value was higher in forest soil than oil palm soil in respect of soil depth. highest and lowest ec values were found at 0-5 cm soil depth both in forest oil palm soil, respectively. at 60-90 cm soil depth ec value was more or less similar to forest and oil palm soil. 4.3 δ13c distribution in different depths of soil maximum negative δ13c value was obtained from 0-5 depth of soil in forest area due to higher biomass on top soil which was controlled by local environmental condition. negative δ13c value decreased with the increase of soil depth in forest and oil palm soil. decomposition of droppings performed δ13c dilution in surface soil. werth and kuzyakov (2010) also reported that top soils δ13c hossain et al. /journal of tropical forestry and environment vol. 7, no. 02 (2017) 62-70 69 values distribution were higher than subsoil because root-to-shoot ratio increases with soil depth, which might enrich soc with 1.2% δ13c by root. as a result, more advanced decomposition in older soc, physical mixing favors the migration of smaller and more strongly decomposed soc particles down the soil profile. this leads to a higher proportion of older and more decomposed soc in deeper horizons. similar results were found by trumbore (2000). 5. conclusions land use significantly affected litter and root biomass, soil ph, ec, organic carbon, available water content in soil. soil organic carbon decreased with the increase of soil depth. the highest organic carbon content was found at 0-5cm depth of forest soil. root biomass as well as lower soc mineralizationcontributed less negative δ13c value in subsurface soil. on the other hand, surface soil was more negative δ13cvalue due to incorporation of litter biomass. sub-surface soc was lower than surface soil in forest soil. this could be caused by reduced incorporation of soc into smaller fractions in lower depth of soil. carbon isotope (δ13c) tracer technique proved that the soil organic carbon dynamics were showed different patterns in different depth of soil due to mineralization of soc, litter biomass and root systems. so, δ13c depth profiles may be a powerful tool to determine the source of organic carbon and to estimate the degree of soc mineralization after conversion of natural forest tooil palm plantation. acknowledgements the authors would like to thank the ministry of agriculture, people’s republic of bangladesh and bangladesh institute of nuclear agriculture for financial support. authors also thank to the school of natural and environmental resource sciences, university kebangsaan malaysia, malaysia for providing the laboratory facility. references adugna, a., abegaz,a. 2016. effects of land use changes on the dynamics of selected soil properties in northeast wellega, ethiopia. soil, 2(1): 63-70. batjes, n.h. 1996. total carbon and nitrogen in the soils of the world. eurasian journal of soil science, 47: 151-163. blake, g.r.,hartage,k.h. 1986. bulk density. in: klute, a. (ed.), method of soil analysis,part i, 2nd ed. physical and mineralogical methods: agronomy monograph no.9,pp. 363–375. board, m.p.o. 2012. overview of the malaysian oil palm industry 2011: selangor: economics & industry development division brady, n.c.,weil,r.r.1996. the nature and properties of soils. prentice hall, pp. 343-490. coleman, d.c., oades, j.m. vehara, g. 1989. dynamics of soil organic matter in tropical ecosystems. niftal project, pp. 5-32. soil and plant analysis council, inc. (2000). soil analysis handbook of reference methods, pp. 33-35. fargione, j., hill,j.,tilman, d., polasky, s.,hawthorne,p. 2008. land clearing and the biofuel carbon debt. science, 319(5867): 1235-1238. flynn, h.c., keller,e.,king, h., sim, s.,hastings,a.,wang, s.,smith,p. 2012. quantifying global greenhouse gas emissions from land‐use change for crop production. global change biology, 18(5): 1622-1635. frazao, l.a., paustian, k., pellegrino cerri, c.e. cerri,c.c. 2013. soil carbon stocks and changes after oil palm introduction in the brazilian amazon. gcb bioenergy, 5(4): 384-390. 70 gibbs, h.k., johnston, m., foley,j.a., holloway, t., monfreda, c., ramankutty, n. zaks,d.2008. carbon payback times for crop-based biofuel expansion in the tropics: the effects of changing yield and technology. environmental research letter, 3(3): 034001. kotowska, m.m., leuschner,c., triadiati, t.,meriem, s., hertel,d. 2015. quantifying above‐and belowground biomass carbon loss with forest conversion in tropical lowlands of sumatra (indonesia). global change biology, 21(10): 3620-3634. kurniawan, s. 2016. conversion of lowland forests to rubber and oil palm plantations changes nutrient leaching and nutrient retention efficiency in highly weathered soils of sumatra, indonesia. gomez, k.a., gomez,a.a. 19984. statistical procedure for agricultural research. 2nd edn. john & wileysons, n.y.,pp. 97-411. jackson, m.l. 1967. soil chemical analysis. prentice hall of india pvt, new delhi, india. pp. 205–226. laganiere, j., angers, d.a.,pare,d. 2010. carbon accumulation in agricultural soils after afforestation: a meta-analysis. global change biology,16: 439-53. mspo(malaysian sustainable palm oil). 2015. malaysia sets timeline for mspo certification compliance, malaysian palm oil certification council (mpocc) official website, http://www.mpocc.org.my/single-post/2017/02/25/malaysia-sets-timeline-for-mspocertification-compliance mendham, d.s., o’connell, a.m. grove,t.s. 2003. change in soil carbon after land clearing or afforestration in highly weathered lateritic and sandy soils of southwestern australia. agriculture ecosystems environment, 95: 143-156. nre(natural resources and environment). 2016. total forested area in malaysia (1990-2014). ministry of natural resources and environment, wisma sumber asli, no. 25 persiaran perdana, presint 4, 62574 putrajaya, malaysia. oelbermann, m., voroney,r.p. 2007. carbon and nitrogen in a temperate agroforestry system: using stable isotopes as a tool to understand soil dynamics. ecological engineering, 29: 342–349. patthanaissaranukool, w., polprasert,c. 2011. carbon mobilization in oil palm plantation and milling based on a carbon-balanced model-a case study in thailand. environment asia, 4(2): 17-26. rasse, d.p., rumpel,c.,dignac,m.f. 2005. is soil carbon mostly root carbon? mechanisms for a specific stabilisation. plant soil, 269: 341–356. rumpel, c. and i. kogel-knabner, 2011. deep soil organic matter – a key but poorly understood component of terrestrial c cycle. plant soil, 338. siangjaeo, s., s.h., gheewala, k. u., chidthaisong,a. 2011. implications of land use change on the life cycle greenhouse gas emissions from palm biodiesel production in thailand. energy sustainable development, 15(1): 1-7. six, j., feller, c.,denef,k., ogle,s., sa, j.c.d.m.,lbrecht,a.a. 2002. soil organic matter, biota and aggregation in temperate and tropical soils-effects of no-tillage. agronomie, 22(7-8): 755-775. townend, j., reeve,m.j.,carter,a. 2001. water release characteristics. soil environ. anal. phy. meth. 2nd edn. revised and expanded, isbn: 0824704142, pp: 111. trumbore, s. 2000. age of soil organic matter and soil respiration: radiocarbon constraints on belowground c dynamics. ecological applications, 10: 399-411. werth, m., kuzyakov,y. 2010. 13c fractionation at the root–microorganisms–soil interface: a review and outlook for partitioning studies. soil biology &biochemistry, 42: 1372–1384. yahya, z., husin,a.,talib, j.,othman, j.,ahmad, o.h., jalloh,m.b. 2010. soil compaction and oil palm (elaeis guineensis) yield in a clay textured soil. american journal of agricultural biological sciences,5(1): 15-19. chapter five: discussion 54 greenhouse gas emissions from plantation to the proceeded wood products via state timber corporation depots for selected tree species using life cycle assessment d.k.l. senadheera 1 , d.m.s.h.k. ranasinghe 2* , w.a.s.b. wahala 3 and h.s. amarasekera 2 1 carbon consulting company, colombo 05, sri lanka 2 department of forestry and environmental science, university of sri jayewardenepura, sri lanka 3 department of tourism management, sabaragamuwa university, sri lanka date received: 20-06-2015 date accepted: 25-09-2015 abstract life cycle assessment (lca) provides a methodological framework for evaluating environmental performance over the life cycle of a product, process, or an activity. in sri lanka, majority of timber for wood based industries comes from homegardens and government owned forest plantations. state timber corporation (stc) is the authoritative body for timber harvesting in state owned forest plantations. this lca study was carried out to calculate greenhouse gas (ghg) emissions of the stc timber movements from the plantation to the finished product. the study concentrated on teak, eucalypt and mahogany species as they represented fast moving commercial timber of high significance. assessment boundary was from the harvesting to the product. updated emission factors were used to calculate the co2 eq units. when considering the emissions during the process, the highest was recorded in the sawmilling process (48% from sawing, 9% from surfacing and 9% from drying). the transportation accounted for 31.25% of emissions while harvesting contributed to 6%. other indirect emissions accounted for 2.75%. keywords: greenhouse gas emissions, embedded carbon, life cycle assessment, forest operations 1. introduction forest ecosystems are important as sinks or sources as a function of their management and condition. it has been estimated that 680×10 6 tcyr -1 is sequestered in forests (eriksson et al., 2007). the amount of carbon in soil is globally about twice that in the atmosphere and three times as much as in the vegetation (ipcc, 2001). thoughtful environmental professionals have long recognised that environmental loads and impacts do not begin and end with the manufacturing process. forest harvesting for wood products alters the natural cycle of carbon. on a country scale, harvesting may significantly change the net c sink source balance related to country’s forest resources and wood utilization (winjum et al., 1998). harvesting influences the soil organic carbon stock. a decline in soil organic carbon following harvesting is commonly assumed because of decreasing litter input and * correspondence: hemanthi.ranasinghe@gmail.com tel: +94 718538975 issn 2235-9370 print/issn 2235-9362 online © university of sri jayewardenepura senadheera et al. /journal of tropical forestry and environment vol. 5. no 02 (2015) 54-59 55 possibly an increased decomposition rate. as a consequence, over a period of about two decades, lifecycle assessment (lca) methodology has been developed with the objective of providing a framework for comprehensive evaluations of resource consumption and environmental emissions associated with the production, use, and disposal of products. the lca studies in forestry and forest products sector is very limited especially due to the traditional thinking that forestry is already environmentally friendly due to the biological production and the wide variety of positive ecological and sociological functions of forest ecosystems. however, the use of agrochemicals in plantation establishment, forest harvesting, processing etc. involved in a forest product emits a considerable amount of greenhouse gases and attempts could be made to minimise these emissions using lca studies. a life cycle analysis for wood begins with the planting to harvesting trees and ends with the disposal of wood products made from those trees. two parallel and related streams of ghg impacts result directly from the harvesting, processing, use and disposal of wood products. firstly, carbon is lost at each step of the processing chain due to the physical breakdown of wood, releasing carbon dioxide, methane and other by-products. secondly, the transportation of wood to mills, transforming into varieties of products and delivery to customers and eventually to landfills (gower, 2003). according to the forest inventory database (fordata) of the forest department sri lanka, forest plantations are distributed over 17 forest divisions, which are largely based on administrative districts, covering all three major climatic zones (i.e., intermediate and dry zones). the database lists 86,363.8 ha of forest plantations in the country. the majority of the forest plantations, except for those in the northern and eastern provinces have been mapped and inventoried. the state timber corporation is the official designated entity to harvest these forests. therefore the main objective of the study was to estimate the greenhouse gas (ghg) emissions of the main processors considering stc as the focal entity using lca method with a view to provide recommendations for minimising ghg emissions. 2. methodology three timber species were selected for this study based on the largest plantations, largest timber volume movements and having key commercial value in the state sector. the boundary of the study was from the plantation (harvesting), transport and processing for the finished product. teak and eucalypt timber came from the state owned plantations located in anuradhapura, kurunegala, kandy, ampara, moneragala and polonnaruwa (for teak) and nuwara eliya and badulla (for eucalypt) while mahogany logs came from mostly homegardens. timber stock movements and transportation data of timber species were obtained from stc regional timber depots. 2.1 wood material flow analysis the flow of the wood material was analysed in each stage of the conversion. generated waste and the by-products were separately quantified and the process conversions were examined. wooden biomass was weighted in each stage. wood volume passed through the process was weighed and the residuals which were separated as left overs, recyclable materials and waste was weighed separately to conduct the wood material flow in selected unit. 56 material 2.2 ghg emission calculation greenhouse gas emissions of the main processors were estimated considering stc as the focal entity and the boundary was harvesting point to the timber depots and the finished product. figure 1 shows the operational boundary of the study. ghg emissions were estimated in each identified functional unit. activity data shown in the table 1 were collected by conducting sample surveys in selected timber depots. figure 1: carbon flow process and emission sources identification within the system boundary. table 1: inventory data collected from sri lanka forest department. process inventory data felling process average age of the log, thinning practices, type of machine used to harvest, working hours, type of fuel and the fuel consumption transportation mode of transportation, type of fuel, fuel consumption, mileage sawmill type of machines used, working hours of the machines, volume of the products, type of fuel used and its consumption, electricity consumption the lca was done following the basic principles of iso 14040 and iso 14044. the global warming potential was calculated using the values of the ipcc fourth assessment report (2007). the results were analysed with centre of environmental science (cml) methodology stated in the lca operational guide to the oso standard (guinée et al., 2001). teak, eucalyptus, mahogany forest plantation / regeneration harvesting primary processing secondary processing wood product manufacturing final disposal transportation energy products by products waste ghg emissions senadheera et al. /journal of tropical forestry and environment vol. 5. no 02 (2015) 54-59 57 the system boundary defines the unit processes to be included in the system. the unit systems included were inputs and outputs in the main manufacturing/processing sequence, distribution/ transportation, production and use of fuels, electricity and heat and manufacture of ancillary materials. co2 emission factors were sourced from the department of food and rural affairs (defra) emission factor data base, the international energy agency (2010), the u.s. environmental protection agency inventories (2008/2013) and the ipcc guidelines for national greenhouse gas inventories 2006. updated emission factors were used to calculate the co2 eq units. table 2 shows the global warming potential in each ghg gas according to the fourth assessment report of the ipccc. table 2: global warming potential, according to the fourth assessment report published by ipccc. greenhouse gas chemical formula gwp carbon dioxide co2 1 methane ch4 25 nitrous oxide n2o 298 hydro fluorocarbons hfcs 124 14,800 per fluorocarbons pfcs 7,390 12,200 sulphur hexafluoride sf6 22,800 methane and nitrous oxide emission factors for grid electricity were derived from the national grid, mix compositions from the sustainable energy authority, sri lanka (2013) and international energy agency (2010) and the intergovernmental panel on climate change (2006) for electricity. in addition to that, emission factor data base (efdb) software developed by ipcc was used to obtain relevant emission factors to calculate ghg sources. following generalized equation was used to calculate ghg emissions for each identifies emission sources. 3. results 3.1 material flow analysis in the primary processing, logs removed from the harvested sites represented approximately 60% of the total volume, hence the storage carbon. it was estimated that 10% was taken as fuel wood, 5% as leftovers at the harvesting site, 23% at the primary processing stage and 2% at the secondary processing stage. 3.2 ghg emissions when considering the total emissions during the process, 6% emissions were from harvesting while transportation accounted for are approximately 31.25%. sawmilling was the highest ghg emitting sub process contributing 48% from sawing and 9% from surfacing and 9% was drying. other indirect emissions accounted for 2.75 % (figure 2). (1) 58 figure 2: percentage contribution of ghg emissions of state timber corporation’s operations. 4. discussion in the present study, the highest emissions were involved in the timber processing which included sawing (48%), surfacing (9%) and drying (9%) followed by transportation (32%), harvesting (6%) and then other indirect emissions (3%). results of similar nature were recorded by peuttmann and bowyer (2002) in usa where 25% out of the total ghg emissions was due to drying of lumber. this was also endorsed by the findings of wilson (2005) who reported that up to 92% of the energy in the lumber and veneer manufacture was spent on kiln-drying. in the present study, the total ghg emissions in the drying process was 9% and the main reason for the reduced figure in the present study was that state timber corporation use air drying against kiln drying which uses less energy. on average, transportation accounted for the next high ghg emissions in the present study and this could be due to many factors including the distance between the plantation to the depot, the conditions of the vehicles, the lack of transport planning etc. in a study on ghg emissions from the use of primary energy in forest operations and long distance transportation of timber in finland, karjalainen and asikainen (1996) reported that from the total emissions of 424.2 gg carbon dioxide, forest improvement work accounted for 8%, cutting of timber 13%, haulage 18% and long distance transportation 57%. findings of the present study were also in agreement with the trend where the emissions from sawmilling and transportation recorded highest compared with harvesting. as the plantation management of the different species was not taken into account, there was no significant differentiation observed between the plant species used in the study. 5. conclusion use of air drying against kiln drying reduced the emissions significantly. however, the large electricity consumption during the sawmilling sub process increases ghg emissions. the type and condition of the equipment in the sawmills and resorting to cleaner fuels could reduce the ghg emissions in the sawmilling stage. locating new depots close to existing plantations may reduce the transportation cost significantly and reduce the ghg emissions. felling 6% transportation 31% sawmilling 48% drying 9% surfacing 3% other 3% senadheera et al. /journal of tropical forestry and environment vol. 5. no 02 (2015) 54-59 59 references amarasekera, h.s. 1996. alternative timber species: a review of their properties and uses. forestry for development, proceedings of annual forestry symposium 1995, depart. of forestry & env. sci., univ. of sri jayewardenepura, sri lanka. eriksson, e., gillesple, a.r., gustavsson, l, langvall, o, olsson, m. sathre, r. and stendhal, j. 2007. integrated carbon analysis of forest management practices and wood substitution, canadian journal of forest research, 37(3): 671-681. gielen, d., kram, t. and brezet. h. 1999. integrated energy and materials scenarios for greenhouse gas emission mitigation. iea/doe/epa workshop on technologies to reduce ghg emissions: engineering-economic analysis of conserved energy and carbon. may 5-7, washington dc, usa. gower, s.t.a, mckeon-ruedifer, reitter, a., bradly, m., refkin, d.j., tollefson, t., souba, f.j., taup, a., embury-williams, l., schiavone, s., weinbauer, a.c., janetos, a. and jarvis, r. 2003. following the paper trails: the impacts of magazine and dimensional lumber production on case study. the h. john heins iii centre for science, economics and the environment, washington d.c. gower, s. 2003. patterns and mechanism of the forest carbon cycle. annual review of environmental resources 28: 169-204. guinee, j.b., bruijn h. de., duin, r.v., huijbregts, m.a.j. 2001. report of a danish-dutch workshop on lca methodologies, 16-17 september 1999 at cml, leiden. international energy agency. 2010. world energy outlook. international energy agency, france. inventory of u.s. greenhouse gas emissions and sinks: 1990-2013 (april 2015) [http://www3.epa. gov/climatechange/ghgemissions/usinventoryreport.html#fullreport] intergovernmental panel on climate change. 2006. ipccc guidelines for national greenhouse gas inventories. japan institute for global environmental strategies (iges) for the ipccc. johnson, l., lippke, b., marshall, j.d., and comnick, j. 2005. life cycle impacts of forest resources activities in the pacific northwest and southeast united states. wood and fibre science 37: 3046. karjalainen, t., pussinen, a. 1994. role of wood based products in absorbing atmospheric carbon. silva fennica 28 (2): 67-80. kinj, ohuchi, t., kii, h., murase, y. 2005. studies on life cycle assessment of sugi lumber. journal of faculty of agriculture of kyushu university, 50(2): 343-351. mackeever, a. and anderson, a., 1998. timber products used to build us single family houses, forest product journal 42(4): 11-18. miner, r.a. and lucier, a.a. 1994. life cycle assessment: considerations in performing life cycle assessments on forest products. environmental toxicology and chemistry 13(8): 1375-1380. nunery, j.s. and keeton, w.s. 2010. forest carbon storage in the northeastern united states: net effects of harvesting frequency, post-harvest retention, and wood products. forest ecology and management, 259(8): 1363-1375. puettmann, m.e. 2000. environmental life cycle assessment of southern pine lumber treated with borate wood preservatives. ph.d thesis, university of minnesota. st. paul, minnesota. sustainable energy authority, sri lanka (2013), grid emission factors. [http://www.info.energy.gov. lk/] winjum, jk, brown, s. and schlamadinger, b. 1998. forest harvest and wood products: sources and sinks of atmospheric carbon dioxide. forest science, 42(2): 272-284. subasinghe /journal of tropical forestry and environment vol. 8, no. 01 (2018) 1-9 1 feature article data dissemination in forestry sector: need, constraints and trends s.m.c.u.p. subasinghe* centre for forestry and environment, department of forestry and environmental science, university of sri jayewardenepura, nugegoda, sri lanka abstract one of the main constraints involved with research and situation analysis in forestry sector is the lack of re-measured data over a long period of time. since the forest dynamics and tree growth takes such a long time to provide valuable insight, the data gathered in a short time period is mostly not useful. further long-term data measured at regular intervals to detect such changes is not feasible without an intervention of a dedicate institute or group of institutes so that they can implement a formal system to collect required data and disseminate in effective manner in a selected platform. due to the rapid change of technology, data disseminated via printed form become less popular at present. further, raw data cannot be provided in bulk via those methods. therefore web-based data dissemination systems, especially web portals became very much popular among the present generations. in addition to the ease of data storage, there are many advantages of having portals such as data upload, data filtering etc. however, if the portals are poorly maintained or if those do not successfully cater the user requirements, the popularity will decline. this paper discusses about the different users of forestry sector data, characteristics of good data dissemination systems, problems faced by the users in data availability and different methods of data dissemination. in addition, advantages and disadvantages of web-based data dissemination systems, especially web portals are also discussed in detail. keywords: web portal, public access to data, stakeholder coordination, improved communication 1. introduction data dissemination is simply defined as getting the right information to the right people at the right time so they can make right things (brigman & hanson, 2000). such a system is necessary to produce and disseminate high-quality statistical data and information timely to meet the various and changing needs of different users. good data dissemination system in forestry sector should provide with an acceptable amount of data or information for varying purposes from basic understanding, policy making to high quality research. data obtained from this type of entity can be used to addresses the full range of issues prevail in the forestry sector by compiling and disseminating data and making explicit plans for improvement of national procedures with best practices (gdds, 2013). good data dissemination system is a structured process through which the related orgnisations commit to improve the quality of the data compiled and disseminated by their statistical systems over the long run to meet the user needs (knbs data dissemination and access policy, 2012). the members that participate in the system determine themselves the priorities they will pursue in a set of statistical development plans that reflect the migration toward full realiaation of the objectives of the data dissemination system as well as recognition of the resource and other constraints that determine the pace of the migration (gdds, 2013). * correspondence: upuls@sjp.ac.lk tel: +94 714450339 issn 2235-9370 print/issn 2235-9362 online © university of sri jayewardenepura daham doi: 10.31357/jtfe.v8i1.3478 2 data or information related to the forestry sector available in different forms are useful for various purposes such as resource assessment (availability of wood and non-wood forest products, conservation values, social values etc.); resource monitoring (forest cover change, quality and existence of habitats, timber yield monitoring etc.); reporting (progress of project activities, status and severity of damages, expansion due to reforestation programmes etc.); planning (implementation of decisions taken on resource management such as harvesting, reforestation, afforestation etc.) and research (conducted by various institutes to find out new information etc.). in order for generating accurate outcomes, it is essential to maintain a proper data dissemination system minimising the bias while increasing the precision. 2. variety of users of forestry data and access although the users of forestry related data vary in numerous way, they can generally be divided into two groups as non-commercial and commercial users. individuals or groups of non-commercial entities such as universities, non-profitable non-governmental organisations and government institutes are grouped into the non-commercial category. they do not make profits by using the available data. however, users of the business sector such as forestry investment companies or regional plantation companies in sri lanka, multinational firms, businesses that have operations all over the world, value added geospatial technology companies etc. can be grouped into the commercial sector. the use of data by this group leads to income generating opportunism for them. both commercial and non-commercial users are re-divided into end-users and value added users. the outputs of the end-users cannot be further used as input data for further analysis and therefore they are considered as consumers of data. the outputs of the value added users, who are considered as data integrators or re-disseminators, can be used as input data for further activities or analysis (global spatial data workshop, 2004). there is a serious concern among certain stakeholders on the matter of right to access data and dissemination of all forms of data collected in forestry sector. this concern is primarily based on three factors which was debated for many years, yet a conclusive agreement has not been reached. the first factor is that the forestry related institutes are public funded and therefore some experts argue that the interested public should bear the right to access data (knbs data dissemination and access policy, 2012). some argue against that view as if all available data are freely disseminated, those data can be unlawfully used against the same institutes or the government which may create unnecessary unpleasant situations. certain countries such as united states of america accepts the right to access to forestry related data and therefore they have a good dissemination system. however, those data may not be provided in raw form and the user may have to make a payment to receive them. the last factor is that most of the forestry sector data are not ethically sensitive or confidential and therefore dissemination will not create issues. further, provision of data increases the transparency of the particular institute so that there is a higher trust on them by the public. 3. characteristics of good information it is important to note that just storing a large amount of data in any form of platform does not efficiently support the users. therefore the factors given below are considered essential for a good data dissemination system. 3.1 coverage if the data collection procedure effectively represent the entire geographic variation in any country covering all forest types, its value becomes very significant. even for a smaller country like sri lanka, the differences of the forest types are high due to its climate and geographic variability. in addition sri lanka has a large amount of forest plantations established in all three climate zones, viz., dry, intermediate and wet, using different species such as teak, eucalyptus, mahogany etc. therefore a good data dissemination system should cover all those variations to cater the requirements of the users. subasinghe /journal of tropical forestry and environment vol. 8, no. 01 (2018) 1-9 3 3.2 periodicity and timeliness proper data dissemination system should recognise that the importance of production and dissemination increases with appropriate periodicity and timeliness (dissemination policy on microdata, 2007). periodicity refers to the frequency of compilation of the data (viz., the relevant period covered by a data observation, e.g., annual, quarterly, monthly, weekly, daily, etc.). the periodicity of a particular data category reflects several factors, including the ease of data collection and compilation, and the needs of analysis (gdds, 2013). 3.3 access by the public dissemination of official data is an essential feature to maintain the trust of the public because readiness and equal access are principal needs for them (gdds, 2013). however, in reality, access rights given for different user groups identified by data dissemination systems could be different, but the possibility of finding or filtering the required information should be reasonably high (knbs data dissemination and access policy, 2012). the advantage of having a web-based data dissemination system is that the access is easier than any other method. further, there is an opportunity for selecting the right users by the agency which disseminates the data by registering them which will hinder the access of unwanted users. some data can be disseminated under payment procedures, e.g., digital maps of different scales etc. in the same system via a payment gateway. 3.4 integrity data integrity refers to the validity of data, but it can also be defined as the accuracy and consistency of stored data. it relates to the validity of data for the period of time during which it is relevant from that source. when data is described as having integrity, it is viewed as being genuine and resilient during a period of time and hence reliable for future use. in order to maintain the integrity, it requires assurances that there are mechanisms in place to prevent accidental and/or intentional unauthorised modification of the data (http://www.blazent.com/difference-data-quality-data-integrity/). 3.5 quality when the term quality is used in reference to data, it conveys a clear statement to the individual consuming it. this largely reflects the context in which it will be used, and therefore its intention and meaning must be clear. different terms such as complete, relevant and consistent are also used to describe data quality. the result of poor data quality, e.g. wrong and inconsistent data, is poor investments and excessively expensive operations. (http://www.blazent.com/difference-data-qualitydata-integrity/). data quality must further given a high priority and thereby the users should be provided with information to assess quality and quality improvements. 4. problems faced by the users in data availability different users of forestry related data expect different data types varying from just averaged values to detailed tree-wise data. therefore with all the efforts made by the data dissemination organisations, problems described below can still be arisen with the available data and information. 4.1 non-existence of required data/information certain cases, the data required by the users may not be available in the dissemination system. therefore the requirements of such users may not be fulfilled. even if such data are available, they could be outdated due to lack of regular updates. 4.2 accuracy, inconsistency and inadequacy available data in the system may not be accurately collected by maintaining required precision. sampling accuracy could also be poor due to improper coverage of the entire geographical variation. http://www.blazent.com/difference-data-quality-data-integrity/ http://www.blazent.com/difference-data-quality-data-integrity/ http://www.blazent.com/difference-data-quality-data-integrity/ 4 they could also be low value because the number of individuals, for example, trees, measured are not sufficient to represent the respective population. 4.3 use of outdated methods for data collection forestry data are sometimes collected using outdated methods causing low accuracy or providing less information (global spatial data workshop, 2004). this is much related to remote sensing where different countries use satellite images of different resolutions for forest cover analysis. for example, landsat tm images provide 30 m spatial resolution while spot images provide 6 m. although forest fragmentation is prominent in tropical countries at present, accurate details may not be available with the data generated using low resolution images such as landsat tm. 4.4 non-availability of data collected at regular intervals other than spatial resolution, temporal resolution of data collection is important to detect the changes of forest cover and ecological succession. therefore the re-measured data should be adequate enough to detect such changes of the resource of interest. the measurement intervals should not be too long so that the important changes will be detected during the analysis. 4.5 lack of coordination between different stakeholder agencies/institutes this becomes a serious problem when the ownership of particular resource is shared by different organisations where the information is gathered and disseminated by all of them. discrepancies between those agencies will arise on the matter of collection of data and their quality minimising the status of the service expected by the users. 4.6 selection of the users in order to minimise the unnecessary data sharing issues, data dissemination organisations need to identify proper users. type of data distributed can also be changed depending on this matter. for example, raw data can be given to the researchers working in the universities and research institutes while summaries of those data can be given to the other types of users. 4.7 prior publications using collected data there could be instances that the users who obtain data from available dissemination systems publish the findings without acknowledging the relevant organisation which provided data. this kind of actions create complexities between two parties because the data dissemination agency looses the ownership of the data and the credibility of the hard work implemented in data collection. 4.8 confidentiality in a few cases, forestry related data come from very sensitive sources which will reveal the information of the persons involved with forest offences. although legally those should be revealed to the police, it is unethical to highlight their identities in research. therefore confidentiality must be strictly maintained by the users or else such data can be kept within the collection organisation without storing in the dissemination platform. 5. methodology of making data available figure 1 illustrates the simplified process of dissemination of data after the collection. the collected data, should, however, be certified by the organisation itself or by an authorised person to increase the quality, integrity and credibility (knbs data dissemination and access policy, 2012). only such data should be made available in a suitable archive so that the users can access via appropriate methods defined by those data dissemination organisations. forestry related data can be made available either separately by each relevant organisation or many organisations working as a single team on a single platform (figure 2). if each organisation separately disseminates the data, e.g., department of forest conservation, sri lanka, such organisation subasinghe /journal of tropical forestry and environment vol. 8, no. 01 (2018) 1-9 5 should maintain its own data dissemination system which could be similar to that of other organisations or unique to the particular organisation. on the other hand, if many organisations such as department of forest conservation, state timber corporation, and department of wildlife conservation work together for data dissemination, it has to be done via a separate team which is responsible for the quality and integrity of data. although the second method is less costly, issues could rise due to the mismatch of interests, data collection procedures, accuracy levels and data collection intervals. therefore those who are responsible for data management archive have to work in very carefully to minimise those issues while maintaining the quality of data. data can easily be disseminated by above mentioned systems using web-based methods. the basic strategy is to disseminate information simultaneously through various media. an increasing emphasis being put on electronic dissemination, may also be supported by multi-languages (knbs data dissemination and access policy, 2012). publications and data may be freely downloaded or ordered directly on the server. data shops is another dedicated way of disseminating data in both print and electronic forms. in close collaboration with the national statistical institutes, data shops sell publications and data to their users, while providing a wide range of tailor-made services, up-to-date products, information searches, data calculation on request etc. databases also provide data for the specific users on their requirements. this could be the widely available type at present as web based databases can be easily formed and such systems are mostly free of charge. publications, another common way of distributing data and related information, are disseminated through the networks of the publication institutes. although raw data in large quantities may not be disseminated though publications, the summaries and the availability of detailed data are included. figure 1: simplified diagram of data dissemination. archiving dissemination collection certifying 6 figure 2: data sharing by different organisations separately (above) and many organisations on a single platform (below). 6. use of web portal for data dissemination with the increase of technology and the use of computers, laptops and smartphones, electronicbased data disseminations become highly popular during the recent past. among such methods, dedicated web portals are considered to be important than the rest (tella et al., 2012). web portal is a specially designed website that brings information from diverse sources, like emails, online forums and search engines, together in a uniform way. usually, each information source gets its dedicated area on the page for displaying information; often, the user can configure which ones to display (dias, 2001). variants of portals include mashups (which uses contents from more than one source) and intranet "dashboards" for executives and managers. 6.1 advantages of a portal in data dissemination numerous advantages of using a portal for data dissemination are seen at present as described in the following sections. due to those reasons, use of portals for data storage and dissemination has become very popular among the forestry sector orgnisations and users. improved communication data can be uploaded through web portals and discussion forums can be established among different user groups. some forestry projects are conducted by a number of experts working in different countries. in such circumstances, data sharing, upload of results and discuss the findings are much easier with a dedicated archive maintained in internet (guzmain, 2005; tella et al., 2012). it will also help to maintain the information up-to-date. institute 01 own dissemination program certifying institute 02 own dissemination program certifying monitoring/maintaining body institute 01 corporate dissemination certifying institute 02 institute 03 institute 04 institute 05 subasinghe /journal of tropical forestry and environment vol. 8, no. 01 (2018) 1-9 7 streamlined processes of access lengthy processes such as exchanging emails etc. which are required for obtaining approval to use data can be minimised via a portal. however, there should be a need of a registration process with proven identities, but still it will save much time of the users. data management newly collected data can be easily uploaded to the portals rather than dissemination via other forms such as annual reports. therefore there is a significant reduction of print and distribution costs. user guidelines can also be easily maintained which helps to increase the knowledge in working with stored data. cross-platform usage data portals can be easily accessed from different operating systems and browsers which are used by different users (ofoegbu et al, 2014; popovic et al., 2009). gradual growth portal can be set up at smaller scale at the beginning to cater the available data dissemination at that time. it will later be grown with the time to be compatible with increase data uploads and number of users. 6.2 issues in web portal development according to the information of the portal, content and collaboration summit (2012), 10% to 15% of portal initiatives are scrapped altogether due to many reasons (http://www.prescientdigital.com/articles/intranet-articles/five-common-portal-problems-and-theirsolutions) as shown in the following section. ignorance of the user requirements by developers end-users may not see a significant value in a portal if it does not directly help them to find the required information. many organisations fail to effectively communicate the benefits of the newly created portals. in such circumstances, it is important to make sure to know the capabilities and qualities that will make the work-lives of the users easier. change of work by the new generation of employees effective knowledge transference has become very much important in the modern world than in the past. the present generations tend to work at their living places rather than dedicated offices and therefore the portals should be compatible not only with different web browsers, but also with different devices such as laptops, tables, mobile phones etc. (global spatial data workshop, 2004). underestimation of the cost and complexity of portal redevelopment projects this can be a source of confusion when trying to narrow down the scope of a portal development project which leads to increased cost/complexity while it grows. in such circumstances, it is inevitable to collapse the whole system losing a platform to disseminate important data in the forestry sector. lack of fresh and relevant content creating contents for users should be viewed as a lifecycle and not as one-time event. therefore the information update should be made at reasonable intervals to keep the faith of the users which leads to enhance the popularity of the data portal. http://www.prescientdigital.com/articles/intranet-articles/five-common-portal-problems-and-their-solutions http://www.prescientdigital.com/articles/intranet-articles/five-common-portal-problems-and-their-solutions 8 lack of a governance model for portals assigning ownership can be one of the most important but challenging tasks during portal development projects, especially when multiple organisations are working together (global spatial data workshop, 2004). this will create conflicts of interests on different data types, causing ultimate destruction of the entire data dissemination system. 7. discussion data dissemination should be considered as one of the key objectives of forestry sector. as in present-day society, access to relevant information is considered to be a strategic privilege, by means of mass media the potential discrimination between the public authorities, the legal civil associations, the business and public sectors is eliminated (dissemination policy on microdata, 2007). it is believed that everyone who is interested has the same opportunity to reach the basic statistical data and to be informed under equal conditions. openness of statistics can be easily realised by means of mass media where the scope of presented data is beyond limitation (ofoegbu et al, 2014). dissemination can be considered like a dandelion whose seed-head is scattered by the wind until it falls on the fertile soil. confusion is one of the major problem with the use of available data as the user may not be able to decide which dataset to be used. this becomes serious once the same information is provided with different projection systems (knbs data dissemination and access policy, 2012). further data on the same natural resource could be disseminated by different agencies in different manner confusing the users. in addition, the slow updates of the data become useless as the importance of such data will be lower with the time. one of the major problem for the users in data access is the need of following lengthy procedures to obtain the permission. there are simple to complex data sharing agreements available in different institutes, even in sri lanka. the process becomes much lengthy if the permission process requires certified letters and multi-scale approvals. some countries, there are national policies which restrict the data access for most of the society and therefore there is no opportunity for obtaining detailed information. further, if the dissemination agency poorly manages the data and dissemination, slow in update assembly and assimilation, the interest of the user will decline. this will further creates issues if there is a weak mechanism for data and information sharing, including collaborative analysis. official statistics must have the confidence of their users to fulfil the purpose of providing the public with information. in turn, confidence in the statistics ultimately becomes a matter of confidence in the objectivity and professionalism of the agency producing the statistics. transparency of its practices and procedures is a key factor in creating this confidence (gdds 2013). acknowledgement the financial support provided by food and agriculture organization of the united nations, usaid and silvacarbon is acknowledged. subasinghe /journal of tropical forestry and environment vol. 8, no. 01 (2018) 1-9 9 references dias c. (2001). corporate portals: a literature review of a new conception information management. international journal of information management, 21, 269–287. dissemination policy on microdata (2007). department of census and statistics sri lanka gdds (2013) the general data dissemination system: guide for participants and users. international monetary fund, washington, d.c. global spatial data workshop (2004). global spatial data and information: development, dissemination and use. lamont-doherty earth observatory, columbia university, palisades, new york, usa guzmán, r. (2005). e-learning for localisation tool training. translation today, 1(2), 14-16. knbs data dissemination and access policy (2012), kenya national bureau of statistics, herufi house, nairobi, kenya. ofoegbu e.o., fayemiwo m.a., omisore m.o., olanrewaju p.o. (2014) a web portal architectural design and implementation for private universities in nigeria. international journal of scientific and research publications, 4(9): 1-8. popovic, a.; lindic, j. stemberger, m.i. jaklic, j. (2009). web triad: the impact of web portals on quality of institutions of higher education: case study of faculty of economics, university of ljubljana, slovenia. issues in informing science and information technology pp. 313-324. tella a, bashorun m.t, adu e.o. (2012) impact of web portals on e-learning. arpn journal of science and technology, 2(8) 717-724. http://www.blazent.com/difference-data-quality-data-integrity/ accessed on 19th may 2018. 36 diversity and distribution of avifauna at the tropical montane cloud forests of horton plains national park p.h.s.p chandrasiri, w.d.s.c. dharmarathne and w.a.d mahaulpatha* department of zoology, university of sri jayewardenepura, sri lanka date received: 2018-03-07 date accepted: 2018-04-08 abstract diversity and distribution of avifauna was studied at the tropical montane cloud forests of horton plains national park, situated in the highland plateau of the nuwara eliya district from september 2015 to may 2016. three main habitats were identified; cloud forest habitat, cloud forest die-back habitat and grassland habitat. nine, 300 m line transects were marked in each of the habitats. avifauna was recorded on three consecutive days of each month while travelling along these transects. seventy eight species of birds were recorded during the study period. this included 66 resident species (with 13 endemic species) and 12 migratory species. the maximum value of the shannon wiener index h' of 2.56 was recorded from the cloud forest habitat. in the cloud forest die-back habitat the h' was 2.49 and in the grassland habitat the h' was 2.31.the jaccard similarity index, between cloud forest and cloud forest die-back was 0.58, and these two habitats had more common species. cloud forest is the major habitat to be protected, with other habitats, in hpnp. hence management of the hpnp should plan more actions to improve long term monitoring plans to warrant the protection of threatened species. keywords: bird diversity and distribution, endemic birds, horton plains, tropical montane cloud forest 1. introduction sri lanka is a tropical island in the indian ocean, at the southern point of the indian sub-continent, with a main island and several small islands. sri lanka is one of the eight ‘hottest hotspots’ out of the 36 biodiversity hotspots in the world (myers et al., 2000). therefore, sri lanka is ranked among the highest in asia, in terms of ‘biodiversity per unit area’ (moe, 2012). sri lanka is rich with 453 avifaunal species recorded at present, including 240 species of breeding residents, of which 27 are endemics and six proposed endemics (gunawardena and weerakoon, 2012). the country is divided into six avifaunal zones, according to the distribution patterns of the resident bird species (kotagama, 1993). these zones are northern or indian zone, low country wet zone, mid-country wet zone, hill country wet zone, dry zone and uva zone. hill country wet zone is one of them, which is rich and abundant with most of the endemic and threatened species (kotagama, 1993, harrison and worfolk, 1999). *correspondence: : mahaulpatha@sjp.ac.lk issn 2235-9370 print / issn 2235-9362 online © university of sri jayewardenepura mailto:mahaulpatha@sjp.ac.lk daham doi: 10.31357/jtfe.v8i1.3481 chandrasiri et al. /journal of tropical forestry and environment vol. 8, no. 01 (2018) 36-49 37 furthermore, there are some threats to the avifauna in sri lanka. because the forest area coverage in sri lanka in 2015 was 33.0%, and despite the value being recorded to be, so it is fast declining (world bank, 2016). there is a difference in the vegetation of highland forests in sri lanka, above 1,500 m (ashton et al., 1997). these forests have been classified as tropical montane cloud forests (wcmc, 1997). in sri lanka, horton plains, hakgala nature reserve, peak wilderness sanctuary and knuckles are the main forests of this particular type. the horton plains national park (hpnp) is a well-known place in sri lanka, as a saddle shaped highland plateau (pethiyagoda, 2012) surrounded by tea and eucalyptus plantations. there were previous studies carried out in the hpnp, as floral and faunal inventory (mfc, 1994), national conservation review (green and gunawardena, 1997) and management plan (dwc, 2005). moreover, they have studied the avifaunal diversity on that studies. however, there were no recorded study after the biodiversity baseline survey at hpnp which was conducted in 2007 by department of wildlife conservation. the aim of this research to fill the research gaps of avifaunal studies in the hpnp. therefore, this study was conducted to record the avifaunal diversity and to determine the population distribution of birds in different habitats in the hpnp. 2. materials and methods 2.1 study area the study was conducted at the horton plains national park (6°47′-6°50′n, 80°46′-80°50′e) in nuwara eliya district at the eastern extremity of the central highlands (figure 1). the hpnp is a protected area under the department of wildlife conservation. the elevation of hpnp is about 2,000 m from mean sea level. the area of the national park is 31.6 km². hpnp was divided into three main habitat types, according to different characteristics of vegetation by using the methods of biodiversity baseline survey at horton plains national park (dwc, 2007). these three habitats were cloud forest, cloud forest die-back and grasslands. the cloud forest was distributed within 1,236 ha (39.7% of total area) with an undisturbed old-growth forest which is low in height (15-20 m) and the canopy trees were characteristically gnarled and twisted, due to the lower temperatures and high winds. the cloud forest die-back was distributed within 956 ha (30.7% of total area). larger area of the canopies in the cloud forest were dead, and therefore it was known as the cloud forest die-back. there were three types of habitats which were totally considered as grasslands. these habitats were dwarf bamboo, tussock grass and carpet grass (dwc, 2007). grassland habitat was distributed in 806 ha (25.8% of the total area) of the national park. 2.2 site selection sampling areas were located by using 1:50 000 analogue maps and 1:10 000 digital topographical maps, of the department of survey. a global positioning system device (garmin, etrex® 10) was used to mark transects within habitats. nine, 300 m line transacts with 20 m swath, were marked in the cloud forest, cloud forest die-back and grassland habitats. 38 figure 1: vegetation map of horton plains national park (source: dwc, 2007). 2.3 data collection all the species of birds seen or heard within transect, were identified by using a 10x50 binocular (nikon, monarch) and recorded by using field guides of harrison and worfolk (1999). identified bird species were classified according to the national red list of 2012 (moe, 2012) and the revised avifaunal list of sri lanka (kaluthota and kotagama, 2009) population of the birds was recorded on three consecutive days of each month, from september 2015 to may 2016 by traveling along transacts, from 05.30 a.m. to 09.30 a.m. finally, opportunistic data and incidental observations were used to supplement information (sutherland et al., 2004). 2.4 data analysis relative abundance [(number of individuals per species/total number of individuals)x100%], shannon weiner diversity index h' was calculated using the equation 1. h'= -∑ (pi ln pi) (1) where; pi=the proportion of the total sample belonging to the i th species to measure the avifaunal diversity chandrasiri et al. /journal of tropical forestry and environment vol. 8, no. 01 (2018) 36-49 39 significant differences between the monthly diversity indices were calculated using the t test. [t= (h'h)/ (varh1 + var h2)1/2] (magurran, 1988). jaccard similarity index {sj} was calculated between the habitat by using the equation 2. sj=sa / (sa + sb + sc) (2) where; sa=number of species unique to the first habitat sb=number of the species unique to the second habitat sc=number of species common in both habitats microsoft excel™ was used to store data and further more calculations and illustrations of the figures. minitab 17™ was used for statistical analysis of variance and t test. 3. results although there were 31 species recorded in the first month, this value was increased to seventy eight by the ninth month. furthermore, the cumulative number of the species was recorded as a plateau in the last five months (figure 2). therefore, it was determined that the sampling effort was adequate for final calculations and analysis. seventy eight species within 33 families of birds were recorded during the study period (table 1). this included 66 resident species (with 13 endemic species) and 12 migratory species. a total of 4,537 individuals belonging to 60 species were recorded in the cloud forest habitat. 1,870 individuals belonging to 45 species were recorded in the cloud forest die-back habitat. moreover 2,897 individuals that belong to 41 species were recorded in the grassland habitat. 31 53 61 64 72 73 76 77 78 0 10 20 30 40 50 60 70 80 90 s e p te m b e r o c to b e r n o v e m b e r d e c e m b e r ja n u a ry f e b ru a ry m a rc h a p ri l m a y 2015 2016 n u m b e r o f b ir d s p e c ie s figure 2: cumulative number of bird species. 40 table 1: resident bird species and total number of species recorded during the study period. scientific name common name ncs gcs c d g prior records family: phasianidae coturnix chinensis linnaeus,1766 blue quail en lc 2 2 0 √ gallus lafayetii lesson, 1831 e sri lanka junglefowl lc lc 144 49 87 √ family: picidae dendrocopos nanus (vigors,1832) brown-capped woodpecker lc lc 1 0 0 √ picus xanthopygaeus (gray & gray, 1846) streak-throated woodpecker en lc 3 0 0 chrysocolaptes lucidus (scopoli, 1786) pe greater flameback lc 8 0 0 √ family: alcedinidae alcedo atthis (linnaeus,1758) common kingfisher lc lc 1 0 0 √ family: meropidae merops philippinus linnaeus,1766* blue-tailed bee-eater cr lc 0 0 16 √ family: cuculidae cuculus varius vahl, 1797 common hawk-cuckoo en lc 2 0 0 √ centropus sinensis(stephens, 1815) greater coucal lc lc 4 0 0 √ cuculus micropterus gould,1838 * indian cuckoo lc lc 2 0 0 √ family: apodidae collocalia unicolor (jerdon,1840) indian swiftlet lc lc 12 17 35 √ hirundapus giganteus(temminck, 1825) brown-backed needletail nt 0 0 2 √ cypsiurus balasiensis (gray,1829) asian palm-swift lc lc 951 189 782 √ tachymarptis melba(linnaeus, 1758) alpine swift en lc 42 13 67 √ family: hemiprocnidae hemiprocne coronata (tickell,1833) crested treeswift lc 1 0 0 family: columbidae columba livia gmelin, 1789 rock pigeon cr lc 0 2 17 √ columba torringtoniae(blyth & kelaart, 1853)e sri lanka woodpigeon vu vu 14 3 0 √ stigmatopelia chinensis(scopoli, 1786) spotted dove lc lc 0 0 1 chalcophaps indica(linnaeus, 1758) emerald dove lc lc 1 0 0 √ ducula aenea (linnaeus,1766) green imperial-pigeon lc lc 5 8 0 √ family: rallidae rallina eurizonoides lafresnaye, 1845* slaty-legged crake cr lc 0 0 2 family: charadriidae vanellus indicus (boddaert,1783) red-wattled lapwing lc lc 0 0 24 √ family: accipitridae pernis ptilorhyncus(temminck, 1821) oriental honeybuzzard nt lc 3 1 1 √ haliastur indus (boddaert,1783) brahminy kite lc lc 6 2 7 spilornis cheela (latham,1790) crested serpent-eagle lc lc 0 0 12 √ accipiter badius (gmelin,1788) shikra lc lc 2 0 1 √ ictinaetus malayensis (temminck, 1822) black eagle nt lc 5 5 4 √ spizaetus nipalensishodgson, 1836 mountain hawk-eagle vu 2 1 0 √ family: corvidae corvus levaillantii lesson,1831 jungle crow lc lc 142 48 144 √ family: campephagidae pericrocotus flammeus(forster, 1781) scarlet minivet lc lc 46 0 0 √ hemipus picatus (sykes,1832) bar winged flycatcher shrike lc lc 48 19 0 √ family: rhipiduridae rhipidura aureola lesson,1830 white-browed fantail lc lc 0 1 0 family: turdidae myophonus blighi(holdsworth, 1872) e sri lanka whistling thrush en en 8 0 1 √ turdus merula linnaeus,1758 eurasian blackbird en 46 4 31 √ family: muscicapidae eumyias sordidus (walden,1870) e sri lanka dull blue flycatcher vu nt 104 60 2 √ copsychus saularis(linnaeus, 1758) oriental magpie robin lc lc 0 0 4 √ chandrasiri et al. /journal of tropical forestry and environment vol. 8, no. 01 (2018) 36-49 41 saxicola caprata (linnaeus,1766) pied bush chat en lc 3 25 188 √ culicicapa ceylonensis swainson, 1820 greyheaded canaryflycatcher lc lc 37 0 0 √ family: sturnidae acridotheres tristis (linnaeus,1766) common myna lc lc 5 2 34 √ gracula ptilogenys blyth, 1846e sri lanka myna vu nt 2 0 0 √ family: sittidae sitta frontalis swainson, 1820 velvet fronted nuthatch lc lc 120 10 0 √ family: paridae pavus major linnaeus, 1758 great tit lc 68 51 0 √ family: hirundinidae hirundo domicola jerdon,1844 hill swallow vu lc 564 173 819 √ family: pycnonotidae pycnonotus cafer (linnaeus,1766) red-vented bulbul lc lc 0 9 4 √ pycnonotus penicillatus blyth, 1851e sri lanka yellow-eared bulbul vu nt 602 445 0 √ family: cisticolidae cisticola juncidis (rafinesque,1810) zitting cisticola lc lc 13 2 84 √ prinia socialis sykes, 1832 ashy prinia lc lc 3 11 0 family: zosteropidae zosterops ceylonensis holdsworth, 1872e sri lanka white eye nt lc 797 447 16 √ family: sylviidae bradypterus palliseri (blyth,1851) e sri lanka bush warbler en nt 25 23 0 √ orthotomus sutorius(pennant, 1769) common tailorbird lc lc 41 7 0 √ family: timaliidae garrulax cinereifrons blyth, 1851e sri lanka ashy-headed laughingthrush en vu 5 4 0 √ pellorneum fuscocapillus(blyth, 1849) e sri lanka brown capped babbler lc lc 3 0 0 √ pomatorhinus melanurus blyth, 1847e sri lanka scimitar babbler lc lc 50 19 0 √ dumetia hyperythra (franklin,1831) tawny-bellied babbler lc lc 1 1 0 rhopocichla atriceps (jerdon,1839) dark fronted babbler lc lc 86 51 0 √ chrysomma sinense (gmelin,1789) yellow eyed babbler lc lc 1 0 0 turdoides rufescens (blyth,1847) e sri lanka orange billed babbler vu nt 17 0 0 √ turdoides affinis (jerdon, 1845) yellow billed babbler; lc lc 2 9 2 √ family: dicaeidae dicaeum erythrorhynchos(latham, 1790) pale billed flowerpecker lc lc 414 108 23 √ family: nectariniidae nectarinia asiatica (latham,1790) purple sunbird lc lc 4 4 0 √ nectarinia lotenia (linnaeus,1766) long billed sunbird lc lc 24 8 11 √ nectarinia zeylonica (linnaeus, 1766) purple rumped sunbird lc lc 4 3 0 √ family: motacillidae anthus rufulus vieillot, 1818 paddyfield pipit lc lc 0 7 105 √ family: estrildidae lonchura striata (linnaus,1766) white rumped munia lc lc 0 0 22 √ lonchura punctulata(linnaeus, 1758) scaly breasted munia lc lc 0 2 55 √ lonchura malacca (linnaeus,1766) tricoloured munia lc lc 5 13 242 √ 42 maximum number of individuals was the hills wallow followed by the asian palm swift. the highest number of species was recorded from the family timaliidae (babblers). the most significant about these findings was that all the species of that family whereas present at horton plains national park. table 2: migratory birds and vagrants species recorded during the study period. (* only the breeding population has been considered in this assessment) scientific name common name ncs gcs c d g prior records family: muscicapidae ficedula subrubra(hartert & steinbacher, 1934) kashmir flycatcher vu 4 0 0 √ muscicapa dauurica pallas, 1811 asian brown flycatcher lc 0 4 0 √ muscicapa muttui (layard, 1854) brown-breasted flycatcher lc 1 0 0 luscinia brunnea (hodgson, 1837) indian blue robin lc 1 0 0 √ family: laniidae lanius cristatus linnaeus, 1758 brown shrike lc 3 3 8 √ family: motacillidae dendronanthus indicu s (gmelin, 1789) forest wagtail lc 9 2 7 √ motacilla flava linnaeus, 1758 yellow wagtail lc 7 0 1 motacilla cinerea tunstall, 1771 grey wagtail lc 12 8 25 √ family: hirundinidae hirundo rustica linnaeus, 1758 barn swallow lc 3 8 11 √ riparia riparia (linnaeus, 1758) sand martin lc 0 0 7 family: laridae chlidonias hybrida (pallas, 1811) whiskered tern lc 0 0 1 family scolopacidae gallinago stenura (bonaparte, 1830) pintail snipe lc 0 0 2 √ abbreviations: c=cloud forest, d=cloud forest die-back, e=endemic species, g=grassland, gcs=global conservation status, ncs=national conservation status, pe=possibly endemic critically endangered (cr), endangered (en), vulnerable (vu), near threatened (nt), least concern (lc) out of the 12 species from the recorded migratory birds at hpnp, the highest number of species were recorded from family muscicapidae (table 2). moreover three species of wagtails were recorded. in addition aquatic birds; whiskered tern and pintail snipe were recorded. of the 78 species that were included for this research there were ten species, which only one individual was recorded (table 1 and 2). lowland common species such as the common kingfisher and the spotted dove were recorded in the least numbers. a total of 19 species of birds that were believed to be nationally endangered, were recorded within the study period. of them blue-tailed bee-eater, rock pigeon (taking into consideration only the wild population for this purpose) and slaty-legged crake were in the cr (critically endangered) category. besides blue quail, streak-throated woodpecker, common hawk-cuckoo, alpine swift, sri lanka whistling thrush, eurasian blackbird, pied bush chat, sri lanka bush warbler and sri lanka ashyheaded laughing thrush were in the en (endangered) category. additionally, sri lanka wood pigeon, mountain hawk-eagle, sri lanka dull blue flycatcher, sri lanka myna, hill swallow, sri lanka yellow-eared bulbul and sri lanka orange billed babbler were in the vu (vulnerable) category. chandrasiri et al. /journal of tropical forestry and environment vol. 8, no. 01 (2018) 36-49 43 there were globally threatened species were recorded: sri lanka whistling thrush (en), sri lanka wood pigeon (vu), sri lanka ashy-headed laughing thrush (vu) and the kashmir flycatcher (vu). there were eight new breeding resident species (streak-throated woodpecker, crested treeswift, spotted dove, slaty-legged crake, brahminy kite, white-browed fantail, ashy prinia, tawny-bellied babbler and yellow-eyed babbler) and four migratory species (brown-breasted flycatcher, yellow wagtail, sand martin and whiskered tern) recorded for the first time in hpnp. of the species of birds which were recorded from the fixed line transects, only 35 species were from the cloud forest while 26 species were from the cloud forest die-back and 23 species from the grassland. therefore these species were only subjected to statistical analysis, while the other recorded species were treated as opportunistic observations. table 3: relative abundance of cloud forest. rank species relative abundance % 1 asian palm swift 20.96 2 sri lanka white-eye 17.56 3 sri lanka yellow-eared bulbul 13.26 4 hill swallow 12.43 5 pale billed flowerpecker 9.12 6 sri lanka junglefowl 3.17 7 jungle crow 3.12 8 velvet-fronted nuthatch 2.64 9 sri lanka dull-blue flycatcher 2.29 10 dark-fronted babbler 1.89 11 great tit 1.49 12 sri lanka scimitar babbler 1.10 13 bar-winged flycatcher-shrike 1.05 14 scarlet minivet 1.02 15 eurasian blackbird 1.01 16 alpine swift 0.92 17 common tailorbird 0.90 18 grey-headed canary flycatcher 0.81 19 sri lanka bush warbler 0.55 20 long-billed sunbird 0.52 21 sri lanka orange-billed babbler 0.37 22 sri lanka woodpigeon 0.30 23 zitting cisticola 0.28 24 indian swiftlet 0.26 25 grey wagtail 0.26 26 forest wagtail 0.19 27 sri lanka whistling-thrush 0.17 28 greater flameback 0.17 29 yellow wagtail 0.15 30 brahminy kite 0.13 31 black eagle 0.11 32 sri lanka ashy-headed laughing thrush 0.11 33 common myna 0.11 34 black-headed munia 0.11 35 green imperial pigeon 0.11 44 table 4: relative abundance of the cloud forest die-back. rank common name relative abundance % 1 sri lanka white-eye 23.90 2 sri lanka yellow-eared bulbul 23.79 3 asian palm swift 10.10 4 hill swallow 9.25 5 pale-billed flower-pecker 5.77 6 sri lanka dull-blue flycatcher 3.20 7 dark-fronted babbler 2.72 8 great tit 2.72 9 sri lanka junglefowl 2.62 10 jungle crow 2.56 11 pied bushchat 1.33 12 sri lanka bush warbler 1.22 13 bar-winged flycatcher-shrike 1.01 14 sri lanka scimitar babbler 1.01 15 indian swiftlet 0.90 16 black-headed munia 0.69 17 alpine swift 0.69 18 velvet-fronted nuthatch 0.53 19 yellow-billed babbler 0.48 20 red-vented bulbul 0.48 21 barn swallow 0.42 22 long-billed sunbird 0.42 23 grey wagtail 0.42 24 green imperial pigeon 0.42 25 paddyfield pipit 0.37 26 common tailorbird 0.37 according to the relative abundance values in the cloud forest habitat (table 3) the asian palm swift was the most common bird (relative abundance=20.96% ) followed by the sri lanka white-eye, the sri lanka yellow-eared bulbul, the hill swallow and the pale-billed flowerpecker. in the cloud forest die-back habitat (table 4) the most common species was the sri lanka white-eye (relative abundance=23.90%) followed by the asian palm swift, the black-headed munia, the pied bush chat and the jungle crow. in the cloud forest die-back habitat (table 5), the most common species was the hill swallow (relative abundance=28.2706) followed by the asian palm swift, the black-headed munia, the pied bush chat and the jungle crow. chandrasiri et al. /journal of tropical forestry and environment vol. 8, no. 01 (2018) 36-49 45 table 5: relative abundance of grassland. rank common name relative abundance % 1 hill swallow 28.27 2 asian palm swift 26.99 3 black-headed munia 8.35 4 pied bushchat 6.48 5 jungle crow 4.97 6 paddyfield pipit 3.62 7 sri lanka junglefowl 3.01 8 zitting cisticola 2.89 9 alpine swift 2.31 10 scaly-breasted munia 1.89 11 indian swiftlet 1.20 12 common myna 1.17 13 eurasian blackbird 1.07 14 grey wagtail 0.86 15 red-wattled lapwing 0.82 16 pale-billed flowerpecker 0.79 17 white-rumped munia 0.75 18 rock pigeon 0.58 19 sri lanka white-eye 0.55 20 blue tailed bee-eater 0.55 21 crested serpent eagle 0.41 22 barn swallow 0.37 23 brown shrike 0.27 from the total species taken into account in this study, 50 species of birds (table 06) were observed opportunistically, while some rare species were also recorded in least numbers and a special feature being, the record of the oriental honey-buzzard in all three habitats. 2.56 2.49 2.31 2.1 2.2 2.3 2.4 2.5 2.6 cloud forest cloud forest die-back grassland habitat figure 3: shannon wiener index of the main three habitats of horton plains. 46 table 6: opportunistic data recorded at three habitats. number common name cloud forest cloud forest die-back grassland total 1. kashmir flycatcher 4 4 2. greater coucal 4 4 3. purple sunbird 4 4 8 4. purple rumped sunbird 4 3 7 5. pied bushchat 3 3 6. brown-capped babbler 3 3 7. oriental honey-buzzard 3 1 1 5 8. barn swallow 3 3 9. ashy prinia 3 1 4 10. streaked-throated woodpecker 3 3 11. brown shrike 3 3 6 12. yellow-billed babbler 2 2 4 13. sri lanka hill myna 2 2 14. shikra 2 1 3 15. indian cucoo 2 2 16. mountain hawk eagle 2 1 3 17. common hawk cucoo 2 2 18. blue-breasted quail 2 2 4 19. yellow-eyed babbler 1 1 20. indian blue robin 1 1 21. emerald dove 1 1 22. brown-breasted flycatcher 1 1 23. crested treeswift 1 1 24. tawny bellied babbler 1 1 0 4 25. common kingfisher 1 1 26. brown-capped pygmy woodpecker 1 1 27. black eagle 5 4 9 28. eurasian blackbird 4 4 29. sri lanka ashyheaded laughing thrush 4 4 30. asian brown flycatcher 4 4 31. sri lanka woodpigeon 3 3 32. scaly-breasted munia 2 2 33. forest wagtail 2 7 9 34. rock pigeon 2 2 35. common myna 2 2 36. brahminy kite 2 7 9 37. zitting cisticola 2 2 38. white-browed fantail flycatcher 1 1 39. sand martin 7 7 40. oriental magpie robbin 4 4 41. red-vented bulbul 4 4 42. sri lanka dull-blue flycatcher 2 2 43. slaty-legged crake 2 2 44. brown-breasted needle-tail 2 2 45. pintail snipe 2 2 46. yellow wagtail 1 1 47. sri lanka whistling thrush 1 1 48. spotted dove 1 1 49. long-billed sunbird 1 1 50. whiskered tern 1 1 chandrasiri et al. /journal of tropical forestry and environment vol. 8, no. 01 (2018) 36-49 47 maximum shannon wiener index (h') was recorded from cloud forest habitat (h'=2.56) while a minimum h' was recorded from grassland habitat (h'=2.31). moreover after applying the t-test, in the cloud forest die-back habitat, the h' is 2.4 (figure 3). bird diversity differed significantly between the cloud forest die-back habitat and the grassland habitat (t=2.2587, df=3826) as well as between the cloud forest and grassland habitats (t=3.9484, df=6484).bird diversity of the cloud forest did not differ significantly from the cloud forest die-back bird diversity (t=0.9325, df=3529). table 7: jaccard similarity index. habitat sa sb sc sum jaccard index cloud forest; cloud forest die-back 22 6 38 66 0.58 cloud forest die-back; grassland 17 14 27 58 0.47 cloud forest ;grassland 24 15 26 65 0.40 jaccard similarity index (table 7) between the cloud forest and cloud forest die-back was at 0.58 and these habitats had more similar species. moreover between the cloud forest die-back and the grasslands, the value was at 0.47 and minimum value, 0.40 was recorded between the cloud forest and the grasslands which had less similar species. 4. discussion though the horton plains national park is relatively smaller than other national parks (dwc, 2007), this area is rich in avifaunal diversity with a large number of bird species (total number of species=78). there are endemic bird species with high population, present within the hpnp. within the study there were some bird species that were not recorded in any of the previous surveys. they consisted of resident breeders such as, the streak-throated woodpecker, the crested tree swift, the spotted dove, the slatylegged crake, the brahminy kite, the white-browed fantail, the ashy prinia, the tawny-bellied babbler and the yellow-eyed babbler. moreover there were migratory species such as the brownbreasted flycatcher, yellow wagtail, sand martin and the whiskered tern. in this study, percentage of the sri lankan breeding residents, 30.19% were recorded. furthermore out of the endemic birds (27 considered endemic birds according to the national red list: moe, 2012) there were 48.15% were from horton plains national park. although the rock pigeon (threatened category:cr) had recoded within the study, however, they were recorded near habitats which were disturbed by humans. therefore, this pigeons should be feral pigeons (columba livia intermedia) which were in lc category. in previous diversity studies done by floral and faunal inventory (mfc, 1994) they have mentioned 87 bird species with 14 endemic species. in addition national conservation review (green and gunawardena, 1997) has recorded 26 species with 5 endemic birds. furthermore management plan (dwc, 2005) has mentioned 87 species with 14 endemics. final study about the bird diversity done by the department of wildlife conservation has recorded 64 species with 13 endemic birds (dwc, 2007). out of the newly recorded species, though the slaty-legged crake was previously not recorded from horton plains national park. however they were appeared in victoria park of nuwara eliya (pethiyagoda, 2012). on the contrary, common bird species within lowlands such as spotted dove and 48 brahminy kite were also observed by present study. sand martin was an irregular visitor (vagrant) and a migratory species, recorded for the first time. there is a significant difference of diversity and distribution of birds, among three habitats. there were more common bird species recorded from the cloud forest and cloud forest die-back habitats. this may be because of there was only little distinction between these two habitats in terms of floristic characteristics (dwc, 2007). habitat preference is highest in the cloud forest, according to the species richness (60) and species diversity (shannon wiener index=2.56). cloud forest is the major habitat to be protected, with other habitats, in hpnp. furthermore, in this study some previously recorded (mfc, 1994) bird species were not observed. night birds such as, spot-bellied eagle owl (bubo nipalensis, hodgson, 1836), was not observed because this study was carried out only in the morning period. moreover, some species such as the black-winged kite (elanus caeruleus, desfontaines, 1789), montagu's harrier (circus pygargus, linnaeus, 1758), crested goshawk (accipiter trivirgatus, temminck, 1824), booted eagle (hieraaetus pennatus, gmelin, 1788) and common kestrel (falco tinnunculus, linnaeus, 1758) were not recorded because of the time limitation. in addition, endemic birds such as sri lanka spurfowl (galloperdix bicalcarata, forster, 1781) and sri lanka grey hornbill (ocyceros gingalensis, shaw, 1811) was not recorded in this study. however, the study is ongoing and the authors will publish their new findings in near future. 5. conclusion present study reveals about the diversity and population distribution of the bird species at the horton plains national park. hence management of the hpnp should plan more actions to improve further long term monitoring plans of avifauna to warrant the protection by minimizing threats. the hpnp is a protected area, however there are other plantations around this area. therefore, it is important to encourage the surrounding plantations to improve resources by practicing environmental friendly performances, such as to develop mixed plantings of eucalyptus with other native fast-growing species (williams, 2015). acknowledgement the authors wish to thank research grant of university of sri jayewardenepura (asp/01/re/sci/2015/34), department of wildlife conservation (permit no wl/3/2/13/15), idea wild organization, the staff of horton plains national park, the research crew of wildlife circle, department of zoology university of sri jayewardenepura and the department of english university of sri jayewardenepura. references ashton, m.s., gunatilleke, s., de zoysa, n., dassanayake, m.d., gunatilleke, n. and wijesundera, s., 1997. a field guide to the common trees and shrubs of sri lanka. colombo, sri lanka: wht publications.430pp. dwc, 2005. horton plains national park. management plan. final draft. protected areas management and wildlife conservation project, department of wildlife conservation, colombo. 91 pp. dwc, 2007.biodiversity baseline survey: horton plains national park. department of wildlife conservation, ministry of environment and natural resources, colombo.40 pp. chandrasiri et al. /journal of tropical forestry and environment vol. 8, no. 01 (2018) 36-49 49 green, m.j.b. and gunawardena, e.r.n., 1997. designing an optimum protected areas system for sri lanka's natural forests. 2 volumes. environmental management in forestry developments project, forest department, government of sri lanka, colombo.399 pp. gunawardena,k. and weerakoon, d.k. 2012. the taxonomy and conservation status of birds in sri lanka. ministry of environment, colombo, sri lanka.114117. harrison, j. and worfolk, t., 1999. a field guide to the birds of sri lanka. oxford university press, oxford. 219 pp. kaluthota, c. d. and kotagama, s.w., 2009. revised avifaunal list of sri lanka. occasional paper no.02.field ornithology group of sri lanka 32pp. kotagama, s. w., 1993. wildlife conservation and development of the south east dry zone. in the southeast dry zone of sri lanka. colombo: agrarian research and training institute. magurran, a. e., 1988. ecological diversity and its measurement. croom helm limited, london. 179 pp. mfc, 1994. research in horton plains national park, sri lanka. final report sumitted to biodiversity support programme. march for conservation, colombo. 68 pp. moe, 2012. the national red list 2012 of sri lanka; conservation status of the fauna and flora. ministry of environment, colombo, sri lanka. 476pp. myers, n., mittermeier, r.a., mittermeier, c.g., da fonseca, g.a. and kent, j., 2000. biodiversity hotspots for conservation priorities. nature, 403. 853–858. pethiyagoda, r., 2012. horton plains sri lanka’s cloud-forest national park, wildlife heritage trust, lake crescent, colombo 2, sri lanka. 320pp. sutherland, w.j., newton, i. and green, r., 2004. bird ecology and conservation: a handbook of techniques (no. 1). oxford university press. 408pp. wcmc, 1997. a global directory of tropical montane cloud forests .aldrich, m., billington, c, edwards, m. and laidlaw, r (eds).world conservation monitoring centre, cambridge, uk. 268pp. williams, r.a., 2015. mitigating biodiversity concerns in eucalyptus plantations located in south china. journal of biosciences and medicines, 3(06). 1-8. world bank, 2016. forest area (% of land area). retrieved on (2016, march, 29) from http://data.worldbank.org/indicator/ag.lnd.frst.zs chapter five: discussion weerakoon et al. /journal of tropical forestry and environment vol. 5. no 01 (2015) 41-46 41 impact of canopy cover on butterfly abundance and diversity in intermediate zone forest of sri lanka b.m.b. weerakoon *1 , a.m.r.s. bandara 2 and k.b. ranawana 3 1 post graduate institute of science, university of peradeniya, sri lanka 2 scienceeducation unit, faculty of science, university of peradeniya, sri lanka 3 department of zoology, faculty of science, university of peradeniya, sri lanka date received: 30-12-2014 date accepted: 14-05-2015 abstract this study was designed to identify the influence of canopy cover on butterfly abundance in young secondary forest and regenerating forest at maragamuwa area of kumaragala forest reserve in naula, matale district of sri lanka. line transect method was used to collect data. hundred meter long five transects were established in each forest area. butterfly abundance data were collected weekly for eight months from january to august 2014. regenerating forest had low canopy cover (<50%) than young secondary forest (20-90%). total of 2,696 butterflies belonging to 87 species in six families were recorded. some butterfly species were restricted to shady areas, but most butterflies were abundant in sunny areas. butterflies in some families (family lycanidae, nymphalidae, pieridae) were abundant in sunny conditions and some families (family hesperiidae, papilionidae) abundant in shade. anova was conducted to identify the variation of number of species (f=54.05, p<0.001) and among abundance (f=10.49, p<0.05) with the canopy cover. species richness was high in moderate canopy cover (20±5%). negative pearson correlation coefficient stated butterfly abundance decreased with the canopy cover (r=-0.91) and species richness decreased with canopy cover (r=-0.85). some butterflies were common in sunny areas and some species were confined to shady areas. however, most of the species were generally found throughout the area. regenerating forest encountered more shrubs than in young secondary forest, which butterflies preferred to food on. main findings of the study were that butterfly abundance was high in sunny areas and butterfly species richness was high in moderate shady areas. keywords: canopy cover, understory, young secondary forest, regenerating forest 1. introduction canopy is the primary barrier on preventing light penetration to forest floor. through the forest succession, canopy cover influence beneath forest vegetation. hence, canopy affects the species heterogeneity of the forest vegetation. thick canopy cover causes reduced understory which dominate by shrubs and herbs. these shrubs and herbs are rich in flowers which serve as a good food source for nectar feeding organisms such as bees and butterflies. butterflies are an important insect group in plant * correspondence: buddhikavray@gmail.com tel: +94 713391713 issn 2235-9370 print/issn 2235-9362 online © university of sri jayewardenepura mailto:buddhikavray@gmail.com 42 pollination. the mutually benefited relationship among plants and butterflies is important in plant reproduction. plants get pollinated while butterfly gets nectar. therefore, butterflies attract to nectar sources around their range. logging and forest fires are the main threats that influence depletion of canopy cover. unlogged forests have significantly large trees, forest density, tree sizes and greater canopy cover compared to logged forests (hill, 1999). through the succession process of a logged forest to a mature secondary forest, different types of vegetation structures dominate. this variation and habitat heterogeneity increases the quality of the habitat. moreover, quality of a particular habitat depends on the number of species utilising it. disturbance to canopy cover changes the habitat quality. canopy gaps influence the understory growth of those areas. as other organisms, butterfly species richness and composition is affected by the habitat quality (collinge et al., 2003). undisturbed canopy has recorded high butterfly abundance and diversity (addai and baidoo, 2013). unlogged forests have significantly high butterfly species richness, abundance, evenness and index of taxonomic distinctiveness (hill et al., 1995). some butterfly species prefer sunny conditions while some others prefer shady conditions. most butterflies which prefer sunny conditions are habitat generalists. they are abundant throughout a wide geographic range. shade preferring butterflies are habitat specialists and have a narrow geographic range. those habitat specialists are mostly confined to climax forests and adversely affected by forest logging (spitzer et al., 1993; hamer et al., 2003; malabika, 2011). hence, there may be a difference in butterfly abundance and diversity under different shade levels. main objective of this study was to identify the impact of canopy cover on butterfly abundance and diversity. 2. methodology the study was conducted in young secondary forest (7°41 / 57 // n, 80°42 / 26 // e) and adjoining regenerating forest (7°41 / 47 // n, 80°42 / 34 // e) in maragamuwa area within kumaragala forest reserve in naula area in matale district in sri lanka. the forest reserve is under the preview of the forest department of sri lanka. vegetation structure of the 30 year old young secondary forest was much mature than the structure of ten year old regenerating forest. young secondary forest consists with few emergent tree species, thick canopy and sub canopy cover, relatively low understory and ground layer. generally ground is covered with dead leaves and fallen branches. but the regenerating forest consists of low canopy cover with short trees, rich understory and ground layer. understory mainly dominates by shrubs and herbs, and ground layer is covered with grass species. hundred meters long line transects were used to collect butterfly abundance data. five transects were established in regenerating forest and five transects in young secondary forest. twenty minutes were spent in each transect. all butterfly species and their abundance was recorded up to five meters distance on both left and right from transect. butterflies were identified according to d’ abrera (1998) and banks and banks (2014). canopy cover in each observation was recorded and it was measured by hemispherical densiometer. data were collected once a week for eight months from january to august 2014 spending morning hours to collect data. one way anova was carried out to identify the variation of species richness and abundance with canopy cover. pearson correlation coefficient was used to identify the relationships among species richness and abundance with the canopy cover using minitab 14 software. relative abundance of butterflies in each family at different canopy cover levels was also calculated. weerakoon et al. /journal of tropical forestry and environment vol. 5. no 01 (2015) 41-46 43 3. results total of 2,696 butterflies of 87 species belonged to six families were recorded during the study. of the 87 species recorded, most species belong to family nymphalidae (n=28) followed by family lycanidae (n=20). least species were belonged to family riodinidae (n=1). regenerating forest had less canopy cover (<50%) compared to young secondary forest (20-90%). canopy in the young secondary forest is more constantly connected with few canopy gaps. however, canopy in regenerating forest is poorly spread and there were more canopy gaps than canopy cover. more individuals and species were recorded at low canopy area, while less abundance and number of species were observed in shade areas. the highest number of butterfly species was recorded at 20±5% canopy level (figure 1). highest butterfly abundance recorded at 10% canopy cover (figure 2). individuals of more light preferring butterflies were recorded in these areas. figure 1: distribution of recorded number of species with percent canopy cover. figure 2: variation of recorded number of butterfly individuals with canopy cover. more adult feeding plants were found in the regenerating forest, which had less canopy cover. most of the understory herbs and shrubs were nectar resources for adult butterflies. most of the butterflies frequently fed on plant species such as lantana camera, stachytarpheta sp. and eupatorium sp. butterflies tend to feed on flowers of tree species in the flowering season. (i.e., homalanthus populifolius, vitex pinnata, cassia siamea and grewia damine). most of herbs and shrubs in understory showed seasonal growth. after the rain these plants grow and blossom. in the dry season 44 these plants dry up. there was a strong negative correlation between canopy cover and butterfly recordings. both recorded number of individuals and number of species decreased with the canopy cover, but recorded number of species increased with number of individuals (r=0.81) (table 1). table 1: pearson correlation coefficient values between abundance and number of species with canopy cover. canopy cover number of individuals number of individuals -0.91 number of species -0.85 0.81 there is a significant difference of recorded abundance between each shade level (p<0.05). furthermore, recorded number of species were significantly differed in each canopy cover level (p<0.001) (table 2). table 2: comparison of abundance and number of species with canopy cover using anova test. canopy cover f p 10% 20% 30% 40% 50% 60% 70% 80% 90% number of individuals 816 632 417 184 313 128 50 124 17 10.49 0.005 number of species 47 61 55 36 45 33 21 34 13 54.05 0.000 all butterfly families (except hespiiridae and riodinidae) showed the highest relative abundance at low canopy cover. moreover, papilionid butterflies were more abundant in moderately sunny areas. species of family hesperiidae preferred moderate shade conditions while family riodinidae mainly recorded in all conditions (table 3). most of the butterflies preferred the sunny conditions, although some preferred shade conditions (i.e., common evening brown-melanitis leda, plain tiger-danaus chrysippus). species with more than ten records were used to produce a box and whiskers plot. according to mean canopy cover of their presence few low shade specialists were found. they were mostly found in more sunny areas, but there were some outlying recordings. most of the butterfly species prefer moderate shade conditions (figure 3). table 3: relative abundance of each butterfly family at different canopy levels. canopy cover family hesperiidae lycanidae nymphalidae papilionidae pieridae riodinidae 10% 12.63 37.57 43.54 19.21 27.31 25 20% 18.95 19.54 23.13 26.60 21.24 0 30% 20.00 14.04 12.59 14.78 17.11 0 40% 13.68 6.26 5.68 4.43 7.28 0 50% 25.26 12.71 7.24 11.82 13.23 25 60% 3.16 2.85 2.96 10.34 6.43 0 70% 1.05 1.33 1.48 3.94 1.82 25 80% 3.16 4.93 3.05 7.39 5.10 25 90% 2.11 0.76 0.33 1.48 0.49 0 weerakoon et al. /journal of tropical forestry and environment vol. 5. no 01 (2015) 41-46 45 figure 3: distribution of each butterfly species with canopy cover%. (note: graph containing butterfly species recorded more than ten times) 4. discussion small herbs and shrubs grow faster and bloom in a short time period. most of these plants are seasonal. flowers of these herbs and shrubs provide nectar for adult butterflies for their energy requirement. regenerating forest hosts many seasonal herbs and shrubs than natural forest. therefore, it provides more floral nectar yield for butterflies than the natural forest. lantana camera, eupatorium sp. are some invasive shrubs that commonly found in regenerating area. these plants have more flowers than native plants. therefore, these plants pollinate via nectar feeding insects such as butterflies than other plants. furthermore, petal color of these invasive plants may be attracting more butterflies. plants such as lantana sp. contain several colors of flowers. thus, these flowers can gather many butterfly species. in terms of nutrients, the main energy source of adult butterflies is floral nectar. hence, nectar is the primary energy source, butterflies assemble where flowers present. canopy cover decreases radiation penetration to forest ground layer. solar radiation is the energy for plant photosynthesis. therefore, shaded areas lack a rich understory. understory consists with many flowering plants which contain sweet nectar. these plants can attract many butterfly species. therefore, these areas support rich butterfly abundance. butterfly abundance and species richness decreased with the canopy cover. however, slight amplified abundance and richness was observed around 50% shade area. most areas had 50% canopy cover. highest shade level in regenerating forest was 50% and young secondary forest had noticeable 50% shade areas. hence, decreasing pattern of abundance and species richness was altered. at 80% shade, another increased abundance and species richness was recorded. this was due to the shade c o m m o n n a m e p e r c e n t c a n o p y c o v e r p s y c h e t a il e d j a y t a m il y e o m a n q u a k e r c o m m o n s m a ll f la t c o m m o n g u ll c e y lo n b ir d w in g b r o w n k in g c r o w c o m m o n r o s e d a r k c e r u le a n m e d u s b r o w n c o m m o n l in e b lu e y e ll o w o r a n g e t ip b lu e m o r m o n a n g le d c a s t o r d a r k w a n d e r e r g r e a t o r a n g e t ip b lu e b o t t le c h e s t n u t b o b c o m m o n c e r u le a n l e s s e r a lb a t r o s s g la s s y t ig e r t h r e e s p o t g r a s s y e ll o w c o m m o n c r o w c o m m o n m o r m o n c o m m o n a lb a t r o s s b lu e t ig e r t in y g r a s s b lu e d a r k b lu e t ig e r c h o c o la t e s o ld ie r c r im s o n r o s e c o m m o n s a il o r l e m o n e m ig r a n t j e z e b e l w h it e f o u r r in g l e m o n p a n s y p la in t ig e r 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0.0 46 preferring butterflies. few butterfly species were shade preferring and they were confined to mature parts of the young secondary forest. presence of these butterfly species affected the abundance pattern and small increase in abundance and richness recorded (figure1 and 2). since butterflies are ectothermic organisms their activity is basically depend on environment temperature. basking is the basic adaptation of butterflies for their thermoregulation. butterflies select a suitable substrate to rest and adjust their wings to reflect maximum solar radiation on their thorax. therefore, most of the butterflies prefer the sunny conditions than shady conditions. however, a few butterfly species prefer shade and these butterflies have dark wing colors to increase the absorbance of solar radiation. more solar radiation increases the environmental temperature and decreases relative humidity. most of the butterfly species prefer conditions with moderate relative humidity. butterflies tend to rest at very low and very high relative humidity conditions. therefore, highest number of species was recorded at moderate canopy cover. regenerating forests were the early stages in forest succession. during succession process young secondary forests will replace regenerating forest. mature secondary forests could be observed following young secondary forests. thus, regenerating forest adjoining to young secondary forest may provide good spectrum of canopy coverage. regenerating forest had low canopy cover with more canopy gaps, while young secondary forest had more constant canopy. therefore, findings of the study were applicable for any forest succession process. 5. conclusion findings of the study highlight that more butterflies prefer sunny and moderately shady areas. however, some species restrict to more shady areas and these species are rare and found only in rich forest habitats. therefore, forests should be preserved to protect these species from extinction. references addai, g. and baidoo p.k. 2013. the effects of forest destruction on the abundance, species richness and diversity of butterflies in the bosomkese forest reserve, brongahafo region, ghana. journal of applied biosciences, 64: 4763-4772. banks, j. and bank, j. 2014. a selection of the butterflies of sri lanka, (3 rd ed), pannipitiya. collinge, s.k., prudic, k.l. and oliver, j.c. 2003. effects of local habitat characteristics and landscape context on grassland butterfly diversity. conservation biology, 17(1): 178-187. d’abrera, b. 1998. the butterflies of ceylon, (1 st ed), d’abrera, colombo 8. hamer, k.c., hill, j.k.,benedick, s.,mustaffa, n., sherratt, t.n., maryati, m. and chey v.k. 2003. ecology of butterflies in natural and selectively logged forests of northern borneo: the importance of habitat heterogeneity. journal of applied ecology, 40: 150-162. hill, j.k., hamer, k.c., lace, l.a. and banham, w.m.t. 1995. effects of selective logging on tropical forest butterflies on buru, indonesia. journal of applied ecology, 32: 754-760. hill, j.k. 1999. butterfly spatial distribution and habitat requirements in a tropical forest: impacts of selective logging. journal of applied ecology, 36: 564-572. malabika, s.k. 2011. impact of tropical forest degradation on nymphalid butterflies: a case study in chandubi tropical forest, assam, india. international journal of biodiversity and conservation, 3(12): 650-669. spitzer, k., novotny, v., tonner, m. and leps, j. 1993. habitat preferences, distribution and seasonality of the butterflies (lepidoptera, papilionoidea) in a montane tropical rain forest, vietnam. journal of biogeography, 20: 109-121. chapter five: discussion bai et al. /journal of tropical forestry and environment vol. 5. no 01 (2015) 47-58 47 biocontrol potential of metarhizium anisopliae (metsch.) sorokin (deuteromycotina: hyphomycetes) against ailanthus defoliator, eligma narcissus (cram.) n.s. bai 1* , t.o. sasidharan 1 , o.k. remadevi 2 and p. dharmarajan 1 1 ashoka trust for research in ecology and the environment, royal enclave, bengaluru, india 2 institute of wood science and technology, malleswaram, bengaluru. india date received: 04-01-2015 date accepted: 11-05-2015 abstract eligma narcissus is recognised as a serious pest of ailanthus in southern india and defoliation of ailanthus by this pest causes apparent loss of growth increment. the common control methods for this pest is mostly insecticides and the concern about the environmental effects of chemical insecticides, has emphasised the use of environmentally more benign microbial agents. among entomopathogens, fungi are the most explored and often act as important natural control agents that limit insect populations. on this point of view, bio efficacy of 25 isolates of metarhizium anisopliae was assessed to establish their virulence against e. narcissus in the laboratory and effective formulations of two potent isolates were subsequently evaluated in the field. mis7 and mis13 were more effective among the different isolates evaluated against e. narcissus. the median lethal concentration (lc50) of all the isolates ranged from 6.46×10 5 conidia/ml to 628.92×10 5 conidia/ml. median lethal concentration of (lt50) of 4.9 and 5.4 days were recorded for mis7 and mis13 respectively at a concentration of 1× 10 7 conidia/ml. virulence tests of the isolates mis7 and mis13 and 0.5% pongamia pinnata seed oil, individually and in different combinations, indicated improved efficacy of the isolates when used in combination and also when combined with seed oil. formulations composed of “mis7+mis13+0.5% pongamia pinnata seed oil” and “mis7+mis13” proved to be superior against e. narcissus, causing 76.30% and 93.93% mortality, respectively. field evaluation of the formulation mis7+mis13+0.5% pongamia pinnata seed oil recorded 5.79 larvae per plant resulting in 60.53% reduction of infestation while the formulation, mis7+mis13 showed 53.76% reduction of infestation with 6.56 larvae per plant. the observations from this study suggest the prospects of using the entomopathogenic fungus, m. anisopliae for the control of e. narcissus. keywords: ailanthus, defoliation, eligma narcissus, metarhizium anisopliae, biocontrol 1. introduction ailanthus excelsa roxb. is a genus of trees belonging to the family simaroubaceae. it is one of the promising fast growing multipurpose tree species in india (tewari, 1992). like any other forest tree, * correspondence: sapnabai@gmail.com tel: +49 19746548242 issn 2235-9370 print/issn 2235-9362 online © university of sri jayewardenepura http://en.wikipedia.org/wiki/tree http://en.wikipedia.org/wiki/simaroubaceae 48 ailanthus is also submitted to the attacks of insect pests. bhasin and roonwal (1954) reported 17 insects associated with ailanthus belonging to 5 orders such as coleoptera, lepidoptera, hemiptera, thysanoptera and isoptera. among the various pest species, eligma narcissus is recognised as a serious pest of ailanthus in southern india (chatterjee and sen sarma, 1968). it is distributed all over india and feeds on almost all species of ailanthus. several species have been recognised and the one that occurs in india has been identified as e. narcissus (roonwal, 1982). it does not show any clear seasonal trend in occurrence. pest build up is generally on increase during september-january (varma, 1986, 1991). jha and sen sarma, (2008) opined that the occurrence of the pest is unpredictable and generally no association is observed with rainfall and the incidence followed a clustered pattern each time the density of the population increased. they feed on young as well as mature leaves. about 20-40 larvae feed voraciously on each leaf at times of heavy defoliation. pest incidence in older plantations is rare compared to young plantations (david and ananthakrishnan, 2004). usually saplings up to five years old are infected and mature trees are free from attack. larvae are reported to feed on green parts of the stem when all the leaves are consumed. defoliation by this pest causes apparent loss of growth increment (varma, 1986; nair, 2007).the common control methods reported for this pest is by using chemicals, mostly insecticides although a few bacterial pathogens and plant extracts are tried. in recent times there has been growing public concern about the environmental effects of synthetic chemical insecticides, which has led to increased use of specific, environmentally more benign microbial agents (cunningham and frankenhuyzen, 1991). biological control involves employment of natural enemies such as predators, parasitoids, pathogens or competitors of a pest to help keep its numbers in check. in general the pathogens function naturally in the environment as population suppressors (saxena, 2008). fungi are the maximum explored organisms among entomopathogens and often act as important natural control agents that limit insect populations (weinzierl and henn, 1991). m. anisopliae is a recognised pathogen of more than 200 insect species, including several major pests. metarhizium has been developed into commercial products for use in several countries (kabuluk et al., 2001). while the products of this fungus have found major use in many developed countries, the efforts on these lines are yet to get popularized in india. hitherto, there are no reports of any study on efficacy of metarhizium fungi against e. narcissus in india. in view of this, the present investigation was undertaken to evaluate the potential of various isolates of m. anisopliae for controlling e. narcissus. bioefficacy of 25 isolates of m. anisopliae was assessed for their virulence against e. narcissus with the objective of identifying potential strains. two most promising isolates and pongamia pinnata seed oil were evaluated individually and in different combinations in the laboratory and the effective formulations were tested in the field. 2. methodology 2.1 insect culture healthy larvae of e. narcissus (figure 1) collected from field were reared in the laboratory and allowed to pupate and develop into adults. male and female moths were released into glass bottles covered with muslin cloth. diluted sucrose (10%) was provided on cotton balls as food. the muslin cloths with eggs were surface sterilized with 1% sodium hypochlorite for 15 min and dipped in sterile distilled water for 10 min and placed over a blotting paper for drying. it was then covered with tender ailanthus leaves and transferred to glass bottles for hatching. the larvae initially established on tender leaves were transferred with fine camel hair brush to plastic boxes (14 cm diameter, 6 cm height) with fresh ailanthus leaves. the petiole of the leaves were wrapped in a layer of moist tissue paper and sealed with parafilm to prevent wilting. every two days, fresh leaves were provided. the pupae were bai et al. /journal of tropical forestry and environment vol. 5. no 01 (2015) 47-58 49 removed from the rearing containers within 24 hours of pupation and transferred to rearing cages for emergence. figure 1: healthy larva of e. narcissus. 2.2 fungus among the 25 fungal isolates used in this study, 16 were collected from field and nine received from different institutions. the isolates from field were recovered and purified from soil and insects. soil samples were collected up to a depth of 30 cm from different study areas. galleria bait method was used to isolate the fungus from soil samples. after removing roots and gravel, soil samples were sifted through a 5 mm sieve. thereafter, plastic boxes (10 cm high, 8 cm diameter) were filled with 100 g of soil and ten galleria mellonella late instar larvae were introduced. the lids were punched for making air holes. the larvae were incubated at 20°c in dark conditions. during the first five days, the boxes were turned once daily to make bait insects penetrate as much soil as possible. after 7-10 days, boxes were examined every other day and dead larvae were collected. cadavers thus obtained and those collected from field were surface-sterilised by dipping sequentially in 70% ethyl alcohol, 1% sodium hypochlorite, and sterile distilled water; each for 3 min. the larvae were dissected and placed on pda/veen’s medium and incubated at 28±1°c and 90% rh to facilitate growth and sporulation of the fungus. slant cultures were prepared from a single colony and stored at -20°c. the viability and virulence of the cultures were maintained by sub culturing and passage through the host at regular intervals (zimmermann, 1986; zayed, 2003). 2.3 pathogenicity studies inoculum preparation metarhizium spores were harvested from pday plate culture by flooding with 10 ml of 0.05% tween 80 in sterile distilled water and dislodging the conidia into suspension with a glass rod. the suspension was filtered through a double layered sterile cheese cloth and centrifuged at 1,700 rpm for 15 min. the supernatant was discarded and the conidia re-suspended in 5 ml sterile distilled water. this stock spore suspension was stored at 4°c for 24 h until spore viability was determined. only cultures with >90% viability were used. counts of conidia were made from the stock suspension using an improved neubauer haemocytometer. spore suspensions containing 1×10 3 , 1×10 4 , 1x10 5 , 1×10 6 , 50 1×10 7 and 1×10 8 conidia/ml sterile distilled water with 0.05% tween 80 were prepared from the stock for bioassay. bioassay bioassay of all the 25 isolates was carried out against the selected pests using inoculum concentrations ranging from 10 3 -10 8 conidia/ml to determine the multiple dose-mortality (lc50) and time-dose-mortality (lt50) responses. ten second instar pest larvae were placed separately in sterile 20 ml vials and 10 ml of fungal suspension was added. the vials were capped and inverted five times over a 5 s period, to ensure that the insects were completely drenched. for the controls, insects were treated with 0.05% tween 80 in the same manner. treated and untreated (control) e. narcissus were transferred with fine camel hair brush into separate plastic boxes (14 cm diameter, 6 cm height) with fresh ailanthus leaves as food source. the petiole of the leaves were wrapped in a layer of moist tissue paper and sealed with parafilm to prevent wilting. the boxes were incubated at 26±1°c, 90% rh, 12:12 (l:d). once in two days, the leaves were replaced with fresh leaves. each concentration of a single isolate was replicated four times. mortality of larvae was recorded every 24 h for eight days after exposure. dead larvae were counted and removed each day to prevent horizontal contamination. the dead larvae from each treatment were incubated in moist conditions to determine if death resulted from mycosis. symptoms of mycosis in cadavers included distension and rigidity, a mottled rusty brown coloring, and development of m. anisopliae hyphae on the exterior of the integument (figure 2). figure 2: mycosed cadavers of e. narcissus. the efficacy of two most promising isolates, mis7 (10 7 conidia/ml) and mis13 (10 7 conidia/ml), and 0.5% p. pinnata seed oil was further evaluated individually and in different combinations as per the above method to determine the synergistic effect of combinations on the mortality of e. narcissus. field trial two formulations of each of the isolates, mis7 and mis13, which proved promising in the laboratory, were evaluated in ailanthus plantations at two locations of odagathur forest division in the vellore district of tamil nadu where peak pest attack was observed. different treatments viz., water formulation of conidia: t1 (mis7 and mis13 at a concentration of 10 14 conidia/ml 0.08% tween 80), oil formulation of conidia:t2 (mis7 and mis13 at 10 14 conidia/ml of 0.08% tween 80 with 0.5% p. bai et al. /journal of tropical forestry and environment vol. 5. no 01 (2015) 47-58 51 pinnata seed oil) along with control t3 (0.08% tween 80) were field evaluated in four year old ailanthus plantation infested by e. narcissus. germination test of the formulations was done one day prior to application and was found to be over 80%. the field layout was in a randomised block design (rbd) consisting of three treatments (two treatments and control) in a plot of size 82×46 m 2 with each treatment replicated four times. the subplots measuring 22×12 m 2 in each replication had seven rows (ten plants each), 2 m apart (five main rows and two skip rows, one on either side of main rows). each subplot was separated from the other by two skip rows 2 m apart (one row from each subplot). the population counts of e. narcissus were recorded a day before the imposition of treatments. the total numbers of larvae on all the leaves of ten randomly selected tagged plants in each plot were recorded. the treatments were imposed using power sprayer. post treatment observations on the number of larvae were recorded at seven and fifteen days after the spray. for each treatment, the averages of all the observations from two locations were used to determine the average percent reduction of pest population calculated using henderson and tilton equation (henderson and tilton, 1955). 2.4 statistical analysis median lethal concentration (lc50) and median lethal time (lt50) values were calculated using probit analysis (finney, 1971). field trial data were subjected to analysis of variance (anova). 3. results 3.1 bioassay mis7, mis13, mis2 and mis20 were more effective among the different isolates evaluated against e. narcissus. the lc50 values of all the isolates ranged from 6.46×10 5 conidia/ml to 628.92×10 5 conidia/ml. the least lc50 value of 6.46×10 5 conidia/ml was exhibited by isolate mis7, followed by mis13 (14.48×10 5 conidia/ml) (table 1). the lt50 values were 4.9, 5.7, 6.8 and 7 days for mis7 at 1×10 7 , 1×10 6 , 1×10 5 and 1×10 4 conidia/ml respectively and 5.4, 6.1, 6.8 and 7.1 days for mis13 (table 2). the least lc50 and lt50 values of mis7 proved it to be the most effective isolate against e. narcissus followed by mis13. hitherto there are no reports of any study on efficacy of metarhizium fungi against e. narcissus in india. the present study assumes significance in this context. chatterjee et al. (1969) reported the ability of entomopathogenic fungi, beauveria bassiana to cause white muscardine disease on e. narcissus. paecilomyces farinosus was isolated from naturally infected pupae of e. narcissus. mortality of e. narcissus larvae within 48-72 h of incubation and 40% pupal mortality were reported due to p. farinosus (mohanan and varma, 1988). p. fumosoroseus was also recognised to be effective in controlling larvae and pupae of e. narcissus (david and ananthakrishnan, 2004). laboratory studies by releasing e. narcissus larvae on host plant leaves treated with p. farinosus spores showed mortality within 72 h which ranged from 77% for late instar larvae to 90% for early instars. some of the inoculated larvae which could pupate, failed to emerge and even when emerged died in few hours (mohammed ali and varma, 1992; mohammed ali et al., 1991). varma and mohammed ali (1986) isolated a bacterial pathogen, bacillus firmus from field population of e. narcissus and confirmed their pathogenicity with 80-100% mortality in larvae within 18-24 h under laboratory conditions. the antifeedant and growth inhibitory effects of methanolic extract of neem seed kernel (nske) was evaluated against final instar larvae of e. narcissus which pointed out the feeding deterrence and growth inhibition of the treated larva in a dosedependent manner (joseph, 2000). 52 table 1: dose-mortality response (lc50) of metarhizium isolates to e. narcissus. e=exponent table 2: time-dose-mortality response (lt50) of metarhizium isolates to e. narcissus. isolates conc. lt50 fiducial limits slope±se χ 2 p lower upper mis 1 1x10 4 8.1 7.2±3.50 0.15 0.99 1x10 5 7.0 15.7±13.90 0.06 0.99 1x10 6 6.7 5.8 12.5 5.8±1.70 0.20 0.99 1x10 7 5.9 5.1 8.0 4.1±0.90 1.81 0.77 mis 2 1x10 4 8.1 7.2±3.50 0.15 0.99 1x10 5 7.0 6.0 29.8 7.0±2.50 0.91 0.92 1x10 6 6.5 5.6 11.0 5.3±1.40 0.43 0.98 1x10 7 5.2 4.6 6.1 4.6±0.90 0.16 0.99 mis 3 1x10 4 8.1 7.2±3.50 0.15 0.99 1x10 5 7.2 6.1 72.7 7.1±2.70 0.35 0.98 1x10 6 7.1 5.9 18.8 5.8±1.80 0.12 0.99 1x10 7 5.8 5.3 7.2 7.1±1.80 0.38 0.98 mis 4 1x10 4 9.0 6.6±3.50 0.25 0.99 1x10 5 8.1 7.2±3.50 0.15 0.99 1x10 6 7.7 6.2 64.9 5.5±1.80 0.26 0.99 1x10 7 6.8 5.6 12.8 4.5±1.20 1.13 0.88 mis 5 1x10 4 9.0 6.6±3.50 0.25 0.99 1x10 5 8.7 6.5 36.5 5.2±1.90 0.82 0.93 1x10 6 7.5 14.3±10.70 0.04 1.00 1x10 7 6.5 5.7 11.0 6.4±1.90 1.12 0.89 mis 6 1x10 4 8.1 7.2±3.50 0.15 0.99 1x10 5 7.6 7.4±3.30 0.23 0.99 1x10 6 7.5 14.3±10.70 0.04 1.00 1x10 7 6.5 5.6 11.0 5.3±1.40 0.43 0.98 rank isolates lc50 (×10 5 ) fiducial limits slope±se χ 2 p lower(×10 5 ) upper(×10 5 ) 1 mis7 6.46 1.37450 57.47463 2.6±0.7 0.027 0.986 2 mis13 14.48 2.29119 1562.76166 2.2±0.7 0.124 0.940 3 mis2 17.87 4.41148 267.80663 3.0±0.8 0.082 0.960 4 mis20 37.35 8.76363 1164.59796 3.2±0.8 0.448 0.799 5 mis1 62.61 13.85899 3275.18707 3.3±0.8 0.264 0.876 6 mis3 110.02 12.70988 56424919.74126 2.3±0.7 0.018 0.991 7 mis19 116.42 14.60324 4672517.23670 2.5±0.8 0.139 0.933 8 mis15 123.14 33.27831 3809.16306 4.8±1.2 0.612 0.736 9 mis23 156.12 22.38051 656584.13095 2.9±0.8 0.320 0.852 10 mis18 157.60 20.04840 3631025.35580 2.7±0.8 0.118 0.943 11 mis4 178.96 63.58669 2.458914e+49 2.5±0.8 0.019 0.990 12 mis10 192.66 31.65834 127503.57566 3.5±0.9 0.087 0.958 13 mis14 201.92 38.73739 53822.93829 4.0±1.0 1.366 0.505 14 mis9 217.13 26.95383 3925480.88407 2.9±0.8 0.107 0.948 15 mis16 256.41 34.62919 1531082.54686 3.3±0.9 0.268 0.874 16 mis8 300.48 32.58871 35029799.27609 2.9±0.8 0.226 0.893 17 mis17 314.67 44.20990 959879.03055 3.6±0.9 0.075 0.963 18 mis6 344.54 41.35598 8152760.21599 3.3±0.9 0.093 0.955 19 mis11 362.13 59.99479 475700.31977 4.3±1.1 0.762 0.683 19 mis21 362.13 59.99479 475700.31977 4.3±1.1 0.762 0.683 19 mis22 362.13 59.99479 475700.31977 4.3±1.1 0.762 0.683 20 mis5 414.59 52.44195 3709702.67431 3.6±1.0 0.106 0.948 21 mis25 416.82 39.57977 5.414953e+21 2.8±0.7 0.187 0.915 22 mis12 424.41 39.57977 5.414953e+13 2.9±0.8 0.712 0.700 23 mis24 628.92 41.49018 1.1956121e+30 2.7±0.8 0.065 0.971 bai et al. /journal of tropical forestry and environment vol. 5. no 01 (2015) 47-58 53 mis 7 1x10 4 7.0 7.4±3.30 0.23 0.99 1x10 5 6.8 5.7 13.1 5.1±1.40 0.48 0.97 1x10 6 5.7 4.9 7.9 3.8±0.80 0.46 0.97 1x10 7 4.9 4.4 5.9 3.8±0.70 0.90 0.92 mis 8 1x10 4 9.0 6.6±3.50 0.25 0.99 1x10 5 8.1 6.5±2.80 0.76 0.94 1x10 6 7.0 6.0 29.8 7.0±2.50 0.91 0.92 1x10 7 6.2 5.4 8.8 5.6±1.50 0.30 0.99 mis 9 1x10 4 9.0 6.6±3.50 0.25 0.99 1x10 5 8.1 7.2±3.50 0.15 0.99 1x10 6 7.1 5.9 18.8 5.8±1.80 0.12 0.99 1x10 7 6.2 5.4 8.8 5.6±1.50 0.30 0.99 mis 10 1x10 4 11.5 5.6±3.40 0.66 0.95 1x10 5 8.1 7.2±3.50 0.15 0.99 1x10 6 7.2 6.1 72.7 7.1±2.70 0.35 0.98 1x10 7 6.2 5.4 8.8 5.6±1.50 0.30 0.99 mis 11 1x10 4 9.0 6.6±3.50 0.25 0.99 1x10 5 7.6 7.4±3.30 0.23 0.99 1x10 6 7.5 14.3±10.70 0.04 1.00 1x10 7 7.0 6.0 27.3 7.0±2.50 0.50 0.97 mis 12 1x10 4 9.5 4.6±1.70 0.37 0.98 1x10 5 9.0 6.6±3.50 0.25 0.99 1x10 6 7.5 6.2 45.2 7.0±2.80 0.47 0.97 1x10 7 6.4 5.6 10.3 5.2±1.40 0.40 0.98 mis 13 1x10 4 7.1 5.9 18.8 5.8±1.80 0.12 0.99 1x10 5 6.8 5.7 13.1 5.1±1.40 0.48 0.97 1x10 6 6.1 5.3 8.6 4.6±1.10 0.47 0.97 1x10 7 5.4 4.8 6.6 4.7±1.00 0.06 1.00 mis 14 1x10 4 9.0 6.6±3.50 0.25 0.99 1x10 5 8.1 7.2±3.50 0.15 0.99 1x10 6 7.2 6.1 72.7 7.1±2.70 0.35 0.98 1x10 7 6.7 5.6 12.3 4.2±1.00 0.27 0.99 mis 15 1x10 4 9.0 6.6±3.50 0.25 0.99 1x10 5 8.2 6.3 11.1 5.7±2.30 1.85 0.76 1x10 6 7.7 6.2 64.9 5.5±1.80 0.26 0.99 1x10 7 6.5 5.5 10.6 4.3±1.00 0.41 0.98 mis 16 1x10 4 8.1 7.2±3.50 0.15 0.99 1x10 5 7.5 14.3±10.70 0.04 1.00 1x10 6 7.2 6.1 72.7 7.1±2.70 0.35 0.98 1x10 7 6.5 5.5 10.6 4.3±1.00 0.41 0.98 mis 17 1x10 4 9.0 6.6±3.50 0.25 0.99 1x10 5 7.5 14.3±10.70 0.04 1.00 1x10 6 7.2 6.1 72.7 7.1±2.70 0.35 0.98 1x10 7 6.5 5.6 11.0 5.3±1.40 0.43 0.98 mis 18 1x10 4 9.0 6.6±3.50 0.25 0.99 1x10 5 7.5 6.2 45.2 7.0±2.80 0.47 0.97 1x10 6 7.1 5.9 18.8 5.8±1.80 0.12 0.99 1x10 7 6.0 5.3 8.4 4.8±1.20 1.02 0.90 mis 19 1x10 4 8.1 7.2±3.50 0.15 0.99 1x10 5 8.1 6.3 167.1 5.0±1.70 0.46 0.97 1x10 6 6.7 5.8 12.5 5.8±1.70 0.20 0.99 1x10 7 5.9 5.3 7.4 6.2±1.50 0.30 0.98 mis 20 1x10 4 8.1 7.2±3.50 0.15 0.99 1x10 5 8.0 6.3 167.1 5.0±1.70 0.46 0.97 1x10 6 6.2 5.4 8.8 5.6±1.50 0.30 0.99 1x10 7 5.7 5.0 7.3 4.7±1.00 0.13 0.99 54 mis 21 1x10 4 1x10 5 9.0 6.6±3.50 0.25 0.99 1x10 6 7.5 6.2 45.2 7.0±2.80 0.47 0.97 1x10 7 6.9 5.8 14.6 5.2±1.50 0.77 0.94 mis 22 1x10 4 1x10 5 7.5 6.1 37.0 5.3±1.70 0.22 0.99 1x10 6 7.0 15.7±13.90 0.06 0.99 1x10 7 6.5 5.5 10.6 4.3±1.00 0.41 0.98 mis 23 1x10 4 1x10 5 8.1 7.2±3.50 0.15 0.99 1x10 6 7.2 6.0 24.0 5.9±1.90 0.38 0.98 1x10 7 6.2 5.4 8.8 5.6±1.50 0.30 0.99 mis 24 1x10 4 9.3 5.6±2.60 1.26 0.86 1x10 5 7.5 14.3±10.70 0.04 1.00 1x10 6 7.5 6.1 37.0 5.3±1.70 0.22 0.99 1x10 7 6.4 5.4 10.2 4.2±1.00 0.25 0.99 mis 25 1x10 4 1x10 5 8.1 7.2±3.50 0.15 0.99 1x10 6 7.1 5.9 18.8 5.8±1.80 0.12 0.99 1x10 7 5.9 5.1 8.0 4.4±1.00 0.13 0.99 significant difference in mortality was observed between the seven combinations tested. increased mortality was recorded with the combination treatments compared to individual treatments. evaluation of various formulations revealed the combination mis7+mis13+0.5% p. pinnata seed oil to be superior over the other treatments which resulted in 76.30% mortality. mis7+mis13 showed 74.82% mortality (table 3). about 6-18% increase in mortality was reported with formulations when used in combinations. synergistic effects of different isolates of a single fungal species, especially metarhizium on insect mortality have not been reported. however, the effect of interaction of b. bassiana, m. anisopilae and l. lecanii was tested by mahmoud (2009). these authors analysed the synergistic and antagonistic interactions based on a comparison of mortality of adults by these fungi when used alone and in combination. the combination of b. bassiana+m. anisopilae gave a synergistic response while the combination of b. bassiana+l. lecanii and m. anisopliae+l. lecanii gave an antagonistic response. the possibility of using mixtures of different species of entomopathogenic fungi for the control of western flower thrips, frankliniella occidentalis was reported by gouli et al. (2008). interaction between the fungi b. bassiana, m. anisopilae and the diatomaceous earth dusts with negligible effect on the viability of conidia was observed by batta (2008). oil based formulations have shown better tolerance to temperature and desiccation, enhanced speed of germination of conidia, improved environmental stability and overall performance as fungal biopesticides (jackson et al., 2010). in the present study, usage of p. pinnata seed oil would have provided these advantages in addition to its insecticidal activity. bai et al. /journal of tropical forestry and environment vol. 5. no 01 (2015) 47-58 55 table 3: evaluation of different combinations of m. anisopliae isolates and p. pinnata seed oil against e. narcissus. treatments mean mortality of e. narcissus mis7 70.33 mis13 64.80 0.5% pongam oil 58.86 mis7 + mis13 74.82 mis7+0.5% pongam oil 73.18 mis13+0.5% pongam oil 68.25 mis7 + mis13+0.5% pongam oil 76.30 sed cd(.05) cd(.01) 0.43 0.87 1.17 sed = standard error of the difference between means; cd = critical difference 3.2 field trial mean number of pest larvae in the experimental plots prior to treatment ranged from 13.07 to 14.13 per plant in location i and 13.99 to 14.27 in location ii. after seven days of treatment, the treatment t2 (mis7+mis13+0.5% p. pinnata seed oil) proved to be superior over other treatments as indicated by the high reduction of infestation in both locations. the treatment t2 recorded 5.01 larvae per plant in location i and 6.59 larvae per plant in location ii which differed significantly from the treatment t1. mean number of 14.12 larvae/plant in location i and 15.03 larvae/plant in location ii were recorded in treatment t3 (untreated control). observations recorded after fifteen days of imposition of treatments revealed significant differences between the treatments. treatment t2 recorded a mean number of 6.13 larvae/plant in location i while t1 recorded 5.57 larvae. in location ii also, t2 was found promising with 5.43 larvae per plant. the control (t3) recorded 14.38 larvae/plant and 15.91 larvae/plant in location i and ii respectively. overall reduction of infestation for different treatments was calculated by combining the data from both the locations. the treatment t2 recorded a mean number of 5.79 larvae/plant which works out to 60.53% reduction of infestation. 53.76% reduction of infestation was observed in t1 (table 4). augmenting the formulation with p. pinnata seed oil increased the overall reduction in infestation of e. narcissus by about 7%. there has been no field trial studies reported using metarhizium isolates against e. narcissus. in one reported case of natural infection by an entomopathogenic fungus p. farinosus, 40% pupal mortality of e. narcissus was reported by mohanan and varma (1988) indicating the prospects of using entomopathogenic fungi for biological control of this pest. control of e. narcissusin nurseries and young plantations using insecticides, fenvalerate and quinalphos was reported by varma (1986) and roonwal (1990). the observations from this study suggest the prospects of using the entomopathogenic fungus, m. anisopliae for the control of e. narcissus. the death of the host insect results from the invasion and colonization of the host body by the fungus and/or due to the toxins produced by the fungus. many chemical pesticides are now being phased out because of their wider impact on ecosystems and this study reaffirms the fact that entomopathogenic fungi can be an important alternative to chemicals for pest management. 56 table 4: reduction of e. narcissus infestation on a. excelsa. treatments average number of larvae/plant location-i location-ii location mean r i (%) 1 dbt 7 dat 15 dat mean 1 dbt 7 dat 15 dat mean dbt dat t1 13.07 6.87 5.57 6.22 13.99 7.38 6.42 6.90 13.53 6.56 53.76 t2 13.86 5.01 6.13 5.57 14.18 6.59 5.43 6.01 14.02 5.79 60.53 t3 14.13 14.12 14.38 14.25 14.27 15.03 15.94 15.47 14.20 14.86 sed cd (0.05) cd (0.01) l-location 0.02270 0.04615 0.06193 t-treatment 0.02780 0.05652 0.07585 d-days 0.02780 0.05652 0.07585 l t 0.03931 0.07993 0.10727 t d 0.04815 0.09790 0.13137 l d 0.03931 0.07993 0.10727 l t d 0.06809 0.13845 0.18579 dbt= day before treatment; dat= days after treatment; ri: reduction of infestation, t1mis7+mis13; t2mis7+mis13+pongam oil (0.5%); t3-0.08% tween 80 (control) the key question that arises with the use of fungi in field is the long term storage and viability as the conservation of viability and efficacy after long term storage and field persistence are very important for the successful application of the formulation under field conditions. further studies to ascertain the efficacy of the isolates in the field even after storage and methods to enhance the field persistence will pave way for successful application of these formulations as a biocontrol agent for ailanthus defoliator, e. narcissus. acknowledgement the authors acknowledge the department of biotechnology, new delhi for providing financial support to carry out this work. authors also acknowledge the director, atree and iwst, bangalore for providing facilities to undertake the study. the permission granted by the pccf karnataka and pccf kerala to undertake survey in the states is also acknowledged. references batta, y.a., 2008. control of main stored grain insects with new formulations of entomopathogenic fungi in diatomaceous earth dusts. international journal of food engineering, 4(1): 56-64. bhasin, g.d. and roonwal, m.l. 1954. a list of insect pests of forest plants in india and adjacent countries. part 2. lists of insect pests of plant genera a (aberia to azima). indian for. bull, 171(1): 93. chatterjee, p.n. and sen sarma, p.k. 1968. important current problems of forest entomology in india. indian forester, 94: 112-117. chatterjee, p.n., singh, p. and misra, r.n. 1969. studies on the biology, ecology, life cycle and parasite complex of ailanthus defoliator, eligma narcissus cramer (noctuidae: lepidoptera), together with morphology of adult and immature stages. indian forester, 95: 541-550. cunningham, j.c. and frankenhuyzen,v.k. 1991. microbial insecticides in forestry. the forestry chronicle, 67(5): 473-480. bai et al. /journal of tropical forestry and environment vol. 5. no 01 (2015) 47-58 57 david, b.v. and ananthakrishnan t.n. 2004. general and applied entomology. tata mc graw-hill publishing company limited, new delhi. finney, d.j. 1971. probit analysis (ed.3). cambridge university press, cambridge, uk. gouli, s., gouli, v., skinner, m., parker, b., marcelino, j. and shternshis, m. 2008. mortality of western flower thrips, frankliniella occidentalis, under influence of single and mixed fungal inoculations. journal of agricultural technology,4(2): 37-47. henderson, c.f. and tilton, e.w. 1955. tests with acaricides against the brow wheat mite. journal of economic entomology, 48: 157-161. jackson, m.a., dunlap, c.a. and jaronski, s.t. 2010. ecological considerations in producing and formulating fungal entomopathogens for use in insect biocontrol. biocontrol, 55: 129-145. jha, l.k. and sen-sarma, p.k. 2008. forest entomology. aph publishing corporation, new delhi. joseph, t.m. 2000. antifeedant and growth inhibitory effects of neem seed kernel extract on ailanthus defoliator, eligma narcissus indica roth. (lepidoptera: noctuidae). entomon, 25(1): 67-72. kabuluk, t., goettel, m., vernon, b. and noronha, c. 2001. evaluation of metarhizium anisopliae as a biological control for wireworms. pacific agri-food research centre (agassiz) contribution no. 165. lomer, c.j., bateman, r.p., johnson, d.l., langewald, j. and thomas, m.b. 2001. biological control of locusts and grasshoppers. annual review of entomology, 46: 667-702. mahmoud,m.f. 2009. pathogenicity of three commercial products of entomopathogenic fungi, beauveria bassiana, metarhizum anisopilae and lecanicillium lecanii against adults of olive fly, bactrocera oleae (gmelin) (diptera: tephritidae) in the laboratory. plant protection science, 45(3): 98-102. mohammed ali, m.i. and varma, r.v. 1992. fungal pathogens of eligma narcissus indica with special reference to paecilomyces sp. phytophaga, 4: 101-109. mohammed ali, m.i., varma, r.v. and sudheendrakumar, v.v. 1991. evaluation of microbial pathogens for biocontrol against insect pests of teak and ailanthus. kfri research report no.73. kfri, peechi. mohanan, c. and varma, r.v.1988.paecilomyces farinosus, a potential biocontrol agent of some lepidopterous tree pests in india. transactions of the british mycological society. 90(1): 119122. nair, k.s. s.2007. tropical forest insect pests: ecology, impact, and management. cambridge university press, cambridge, uk. roonwal, m.l. 1990. field-ecological observations on the ailanthus excelsa defoliator, eligma narcissus indica (lepidoptera, noctuidae), in peninsular india. indian journal of forestry. 13(2): 81-84. roonwal, m.l. 1982. illustration of the life history stages of the ailanthus defoliator eligma narcissus indica (lepidoptera: noctuidae). indian journal of forestry. 54: 270-276. saxena, h. 2008. microbial management of crop pest. journal of biopesticides, 1(1): 32-37. senapati, s.k.1999. conservation and utilisation of natural enemies of crop pests and diseases under terai region of west bengal. research report submitted to bidhan chandra krishi viswavidyalaya, north bengal campus, west bengal. tewari, d.n.1992. tropical forestry in india. international book distributors, dehra dun. varma, r.v. 1986. seasonal incidence and possible control of important pasts in plantations of ailanthus triphysa. kfri research report no.39. varma, r.v. 1991. spatial and temporal distribution of ailanthus pests, eligma narcissus and atteva fabriciella. kfri research report no. 78. 58 varma, r.v. and mohammed ali, m.i. 1986. bacillus firmus as a new insect pathogen on a lepidopteran pest of ailanthus triphysa. journal of invertebrate pathology. 47: 379-380. weinzierl, r. and henn, t. 1991. alternatives in insect management: biological and biorational approaches. north central regional extension publication, cooperative extension service, univ. of illinois at urbana-champaign. weinzierl, r., henn, t., koehler, p. g. and tucker, c. l. 2005.microbial insecticides. series eny-275 (in081), entomology and nematology department. ifas extension, university of florida. zayed, a. 2003. pathogenecity of two beauveria bassiana indigenous isolates towards the greater wax moth galleria mellonella larvae in egypt. efflatounia. 3: 10-14. zimmermann, g. 1986. the galleria bait method for detection of entomopathogenic fungi in soil. journal of applied entomology.102: 213-215. chapter five: discussion liyanage & manage /journal of tropical forestry and environment vol. 5. no 02 (2015) 13-25 13 optimisation of environmental factors on oil degrading bacteria isolated from coastal water and sediments in sri lanka g.y. liyanage1 and p.m. manage1 * 1 department of zoology, university of sri jayewardenepura, sri lanka date received 25-11-2015: date accepted: 07-12-2015 abstract better understanding of the mechanisms of hydrocarbon degrading microorganisms and effect of some environmental factors is critical for the optimisation of the bioremediation processes. temperature, ph, nitrate and phosphate are the major factors that influence there mediation process of bacterium. in the present study, optimisations some selected physico-chemical parameters (temperature, ph, nitrate and phosphate) were carried out on bacillus cereus, enterobacter sp. and enterobacter ludwigii which were previously isolated as potential oil degraders. the bacteria showed maximum degradation of crude oil at 33 o c where the desirable ph was 8.6 for all the isolates except e. ludwigii (ph 5.4). a significant degradation (p < 0.05) of oil was detected by b. cereus (80% to 98%), enterobacter sp. (73% to 90%) and e. ludwigii (70% to 83%) respectively with increasing of nitrate concentration from 0.1 to 2.5 ppm. significant degradation of oil was not detected in the control and when bacteria were enriched with phosphate. results of this study revealed that the bacterial remediation of oil is governed by nutritional status with special emphasis of nitrate enrichment in the environment. thus, the results revealed that bacteria could be a useful tool to remove oil from the contaminated environment as eco-friendly, low cost application. key words: bioremediation, crude oil, bacillus cereus, enterobacter sp., enterobacter ludwigii 1. introduction oil spill pollution, a severe environmental problem across the world, is growing with increased levels of oil production and global transport. its causes are either accidental or due to operation wherever oil is produced, transported, stored and used on sea or land (mehrasbi et al., 2003). the hydrocarbons like pahs (poly aromatic hydrocarbons) have caused extensive damage to the local ecosystems since accumulation of pollutants in animals and plant tissues may cause progeny’s death or mutation (alvarez et al., 1991). this is mainly due to an accumulation of pahs through food chain. ultimately the effect on human health in high because humans are frequently the last part of the food chain. therefore, dealing with these problems and to adopt appropriate solutions, fundamental and advance researches with policies are needed. hanson et al. (1997), sartoros et al. (2005), xiaojun et al. (2008) and joel et al. (2011) documented that bioremediation is more affordable application to remove oil contamination when compare with available physical and chemical removal methods. bioremediation is the treatment process that uses microorganisms such as yeast, fungi and bacteria to break down, or degrade hazardous substance into less toxic or nontoxic substances (kim et al., 2005). * correspondence: pathmalal@sjp.ac.lk tel: +94 718538975 issn 2235-9370 print/issn 2235-9362 online © university of sri jayewardenepura 14 during the remediation process, specific microorganisms consume organic substances in crude oil as sole carbon source for their energy requirement (bouwer and zehnder, 1993) and the aerobic and anaerobic respiration mechanisms convert hazarders’ hydrocarbon in the environment to less harmful compounds such as carbon dioxide, methane and water (farshid et al., 2011). corynebacterium ulcerans, c. amycolatum, bacillus badius and micrococus varians were recorded as potential oil degradates (omotayo et al., 2012) where chin et al., (2008) documented that yokenella spp., alcaligenes spp., roseomonas spp., flavobacter spp., sphinogo bacterium spp. and moraxella spp. as petroleum hydrocarbon-degraders. liyanage and manage (2014) reported that b. cereus, enterobacter sp. and e. ludwigii as crude oil degraders which were isolated from coastal environment in sri lanka. bioremediation processes are governed by some environmental factors such as type and amount of crude oil present in the environment, environmental temperature, nutrients such as no 3, po4 3, ph, aeration, water acidity, type and population density of hydrocarbon degrading microorganisms and contaminant mobility (dragun, 1998; mace, 2012). microbial growth rates in the environment are mainly depending on the temperature and rates of degradation decrease with decreasing temperature. (gibb et al., 2001). toone et al., (2013) documented that degradation mechanisms are enzyme mediated and depend on intracellular and extracellular enzyme activity of the bacteria. furthermore, the incomplete microbial degradation occurs when the ambient environment does not contain significant concentrations of nutrients such as nitrogen and phosphorous (prince et al., 2002). thus, inorganic nutrients are limiting factors for the natural biodegradation process (trindade et al., 2002; efsun et al., 2013). the majority of microorganisms thrive best in the ph range of 6 to 8 (omatayo et al., 2012) and adjustment of ph range from 4.5 to 7.4 was resulted in a near doubling of biodegradation rates of hydrocarbon (leahy and colwell, 1990). thus, the manipulation and optimisation of these factors are needed to enhance the remediation process of pollutants in the environment (dragun, 1998; boopathy, 2000). south asian countries not only import much of oil for domestic consumption, but india, maldives, pakistan and sri lanka lie close to the main shipping route that connects the middle east to the far east (itopf, 2012). several oil spills were recorded around the sri lankan sea during past few years (mepa, 2012). spillage near to panadura sea area was the most recent event. considering the danger and environment impact on biodiversity, numerous solutions have been proposed by national and international agencies to remove oil from contaminated areas. however, the main limitations to use available techniques are inefficient trace level adsorption, hazardousness of chemicals and non-accessibility due to high cost (kishore. and ashisk, 2007). thus, to minimise the environmental effects of oil pollution, in situ bioremediation has been suggested (mepa, 2012). therefore, the present study discusses the in vitro optimisation of environmental factors for three crude oil degrading bacteria strains isolated from oil contamination sites in the coastal environment in sri lanka. those bacteria strains were identified as bacillus cereus (km504128), enterobacter sp. (km4055978) and e. ludwigii (km504129) using 16s rna sequences. 2. methodology 2.1. materials and reagents crude oil (100%) required for the present study was received from sri lanka petroleum corporation (pvt) ltd. bacteriological grade chemicals were purchased from sigma, aldrich © while molecular grade chemicals were purchased from promega © , usa. liyanage & manage /journal of tropical forestry and environment vol. 5. no 02 (2015) 13-25 15 2.2 bacteria for degradation studies previously isolated oil degrading bacteria (liyanage and manage, 2014), identified as bacillus cereus (km504128), enterobacter sp. (km4055978) and e. ludwigii (km504129) were used in the present study to optimise some selected physio-chemical environmental factors for bacterial degradation kinetics. 2.3 preparation of bacteria cultures for optimization of environmental factors a loop of each bacterial strain was transferred into 5 ml of liquid lurial bertani (lb) medium and incubated at 25 o c. exponentially growing cultures were centrifuged at 1000 rpm for 15 minutes. the resulted pellets were re-suspended in 0.01m phosphate buffer solution (pbs) and kept overnight to let out residual carbon content. then the suspensions were centrifuged at 1000 rpm for 15 minutes and the pellets were washed three times using pbs. turbidity of all bacterial suspensions were equalized (a 590=0.35) using spectrophotometer (spectro uv-vis double beam pc) (manage et al., 2009). equalised bacterial suspensions were used to optimisation some of the physic-chemical factor such as temperature, ph, phosphate and nitrate. 2.4 effect of temperature on crude oil degradation filtered sterilised sea water was inoculated by 0.5 ml of overnight starved bacteria culture. then 1% (v/v) crude oil was added to make final volume of 10 ml in universal bottles. samples were incubated in three different temperatures at 23 o c, 28 o c and 33 o c respectively in the shaking incubator at 100 rpm. one milliliter of sub-samples was collected at two days intervals for a period of 14 days to determine the concentration of crude oil. 2.5 effect of phosphate and nitrate concentration on crude oil degradation phosphate concentration in sea water varies between 0.002-0.05 ppm while the nitrate levels were between 0.1-2.5 ppm (james, 2009; liyanage and manage, 2014). in order to determine the effect of phosphate on the crude oil degradation, filtered sterile sea water was prepared at final concentrations of 0.002 ppm and 0.05 ppm supplemented with kh2po4. filter sterilised sea water was inoculated by 0.5 ml of overnight starved bacteria culture and 1% (v/v) crude oil at final volume of 10 ml in universal bottles. the bottles were incubated at 33 o c in 100 rpm. the temperature was determined based on the results of the present study and literature (efsun et al., 2013). one milliliter of sub-samples was removed at two days intervals for a period of 14 days and the concentration of crude oil was measured spectrophotometrically. same set of experiment procedure was followed to study the effect of on remediation of crude oil by the bacterium. nh4no3 enriched sea water with varying concentrations (0.1-2.5 ppm) were used as nitrate source. 2.6 effect of ph on crude oil degradation filtered sterile sea water in triplicate was supplemented with 1% (v/v) crude oil and 0.5 ml of exponentially growing culture of bacteria at final volume of 10 ml into the universal bottles. ph was adjusted to 5.4, 7.2 and 8.6 by adding 1.0m naoh or 1.0m hcl where appropriated. the samples were incubated in the shaking incubator at 33 o c in 100 rpm. one millilitre of subsamples was collected at two days intervals for a period of 14 days to determine the concentration of crude oil. 16 0 2 4 6 8 10 12 0 2 4 6 8 10 12 14 c r u d e o il c o n c e n tr a ti o n (g /m l) × 1 0 -3 incubation time (days) 0 2 4 6 8 10 12 0 2 4 6 8 10 12 14 c r u d e o il c o n c e n tr a ti o n (g /m l) × 1 0 -3 incubation time (days) 2.7 estimation of crude oil concentration in order to estimate residual crude oil, 10 ml of analytical grade n-hexane was added to a flask containing 1 ml of sub-sample removed from the degradation experiment and then transferred in to a separating funnel to extract oil. the extracted aliquot was evaporated to dryness in the water bath at 69 o c and residue oil was dissolved in 10 ml of n-hexane and the concentration was measured according to omatayo et al., (2012) using visible spectrophotometer at 400 nm. concentration of oil in the sample was obtained using the pre-prepared standard curve and the dilution factor was considerate to calculate the actual concentration (latha and kalaivani, 2012). recovery of analytical procedure was maintained to keep more than 95% before samples were subjected to final measurement (liyanage and manage, 2014). 2.8 determination of degradation rates the degradation rates (h) of the bacteria were calculated using the equation bellow, where “co” and “c” are the concentration of crude oil at the beginning and at the end of the time interval “t” respectively (manage et al., 2000). 3. results 3.1 effect of water temperature on bacterial degradation of crude oil figure 1: (a) (b) (c). degradation of crude oil (0.01 gml -1 ) by bacteria in different temperatures. 23 o c (black square), 28º c (close circle) and 33º c (open circle). (a) b. cereus 0 2 4 6 8 10 12 0 2 4 6 8 10 12 14 c r u d e o il c o n c e n tr a ti o n (g /m l) × 1 0 -3 incubation time (days) (b) enterobacter sp. (c) e. ludwigii liyanage & manage /journal of tropical forestry and environment vol. 5. no 02 (2015) 13-25 17 figure 1 (a), (b) and (c) illustrate the degradation of crude oil by b. cereus, e. ludwigii and enterobacter sp. at three different temperatures. when temperature increased to 28 o c and 33 o c the degradation of crude oil by the bacteria isolates were initiated without a lag phase was detected. on the other hand, degradation at 23 o c was slow in all bacteria strains and remained less than 60% except b. cereus following 14 days of incubation. table 1: degradation rates of crude oil by bacteria isolates in different temperature. incubation time (days) name of bacteria degradation rate (day -1 ) 23 o c 28 o c 33 o c 0-2 b. cereus 0.540 ±0.008 0.740 ±0.008 1.510 ±0.002 enterobacter sp. 0.470 ±0.007 0.652 ±0.008 0.812 ±0.011 e. ludwigii 0.350 ±0.005 0.581 ±0.008 0.678 ±0.003 2-4 b. cereus 0.480 ±0.008 0.642 ±0.008 1.213 ±0.002 enterobacter sp. 0.450 ±0.007 0.583 ±0.008 0.585 ±0.011 e. ludwigii 0.420 ±0.005 0.564 ±0.008 0.572 ±0.003 4-6 b. cereus 0.475 ±0.008 0.689 ±0.008 1.012 ±0.002 enterobacter sp. 0.472 ±0.007 0.595 ±0.008 0.523 ±0.011 e. ludwigii 0.465 ±0.005 0.578 ±0.008 0.575 ±0.003 6-8 b. cereus 0.515 ±0.008 0.712 ±0.008 1.112 ±0.002 enterobacter sp. 0.532 ±0.007 0.612 ±0.008 0.586 ±0.011 e. ludwigii 0.486 ±0.005 0.593 ±0.008 0.590 ±0.003 8-10 b. cereus 0.315 ±0.008 0.432 ±0.008 0.765 ±0.002 enterobacter sp. 0.332 ±0.007 0.392 ±0.008 0.543 ±0.011 e. ludwigii 0.416 ±0.005 0.393 ±0.008 0.323 ±0.003 12-14 b. cereus 0.115 ±0.008 0.102±0.008 0.117±0.002 enterobacter sp. 0.087±0.007 0.088 ±0.008 0.102 ±0.011 e. ludwigii 0.076 ±0.005 0.077 ±0.008 0.089 ±0.003 at 33 o c 92% removal of oil was detected by b. cerues, whereas enterobacter sp. and e. ludwigii removed 79% and 88% respectively at 14 days of incubation. the highest degradation percentage of oil was recorded at 33 o c and it was significantly different from the removal percentages of crude oil obtained at 23° c and 28° c respectively. the rate of crude oil degradation by any bacterial isolate relies mainly on the incubation temperature. the highest degradation rate of oil was detected for all bacteria strains at 33 o c (table 1) where b. cereus showed the highest degradation rate (1.510 ±0.002 d -1 ) after two days of incubation. thus, 33 o c temperature was selected as optimum temperature to carry out the rest of experiments planned in the present study. degradation rate of b. cereus was 0.540±0.008 d -1 and 0.740±0.008 d -1 at 23 o c and 28 o c respectively. enterobacter sp. and e. ludwigii showed 0.812±0.011 d -1 and 0.678 ±0.003 d -1 degradation rates at 33 o c after 2 days of incubation respectively. in order to evaluate the possible influence of nutrients, especially nitrates and phosphates on bacterial degradation of crude oil, bacterial cultures were incubated separately in different concentrations of nitrate and phosphate with crude oil. 18 0 2 4 6 8 10 12 0 2 4 6 8 10 12 14 c r u d e o il c o n c e n tr a ti o n (g /m l) × 1 0 -3 incubation time (days) (b) enterobacter sp. 3.2 effect of nutrients on degradation of crude oil the phosphate concentration in the sea water at the time of bacterial isolation was ranged between 0.002 to 0.05 ppm. similar concentration range of phosphate was used to study degradation kinetics of oil in vitro in the present study. significant degradation of oil with inoculation of phosphate was not recorded (figure 2). the degradation rate of b. cereus varied between 0.735±0.002 d -1 0.755±0.008 d -1 at 0-2 days of incubation and maintained more or less constant degradation rate (0.642±0.008-0.692±0.005 d -1 ) at 2-8 days of incubation for each phosphate concentration. then degradation rate increased from 0.642±0.008 d -1 to 0.756±0.003 d -1 at 8-10 days of incubation and then decreased to 0.102±0.002 d -1 at 10-14 days of incubation (figure 2(a)). degradation rate of oil by enterobacter sp. was changed between 0.457±0.003 d -1 -0.682±0.021 d -1 at 0-8 days and was increased to 0.692±0.001 d -1 at 8-10 days. there after degradation rate was decreased from 0.692±0.021 d -1 to 0.069±0.003 d -1 at 10-14 days (figure 2(b)). significant difference of degradation rates was not detected between control and experiments setup for enterobacter sp. as well. at each phosphate concentration e. ludwigii also showed less or more constant range of degradation (0.386 to 0.525 d -1 ) at 0-12 days and then gradually decrease (0.072 to 0.083 d -1 ) at 12-14 days of incubation (figure 2(c)). figure 2: degradation of crude oil (0.01g/ml) by bacteria isolates with phosphate enrichment. (a) b. cereus (b) enterobacter sp. (c) e. ludwigii; 0.002 ppm (close square), control (close circle) and 0.05 ppm (open square). 0 2 4 6 8 10 12 0 2 4 6 8 10 12 14 c r u d e o il c o n c e n tr a ti o n ( g /m l) × 1 0 -3 incubation time (days) (a) b. cereus 0 2 4 6 8 10 12 0 2 4 6 8 10 12 14 c r u d e o il c o n c e n tr a ti o n (g /m l) × 1 0 -3 incubation time (days) (c) e. ludwigii liyanage & manage /journal of tropical forestry and environment vol. 5. no 02 (2015) 13-25 19 0 2 4 6 8 10 12 0 2 4 6 8 10 12 14 c r u d e o il c o n c e n tr a ti o n (g /m l) × 1 0 3 incubation time (days) 0 2 4 6 8 10 12 0 2 4 6 8 10 12 14 c r u d e o il c o n c e n tr a ti o n (g /m l) × 1 0 3 incubation time (days) table 2: degradation rates of crude oil by bacteria with phosphate enrichment. incubation time (days) name of bacteria degradation rate (day -1 ) control 0.002 ppm 0.005 ppm 0-2 b. cereus 0.735 ±0.008 0.740 ±0.008 0.755 ±0.002 enterobacter sp. 0.682 ±0.007 0.652 ±0.008 0.675±0.011 e. ludwigii 0.479 ±0.005 0.481 ±0.008 0.478 ±0.003 2-4 b. cereus 0.657 ±0.008 0.642 ±0.008 0.659 ±0.002 enterobacter sp. 0.595 ±0.007 0.603 ±0.008 0.585 ±0.011 e. ludwigii 0.429 ±0.005 0.432 ±0.008 0.439 ±0.003 4-6 b. cereus 0.675 ±0.008 0.689 ±0.008 0.654 ±0.002 enterobacter sp. 0.587 ±0.007 0.593 ±0.008 0.579 ±0.011 e. ludwigii 0.458 ±0.005 0.461 ±0.008 0.455 ±0.003 6-8 b. cereus 0.683 ±0.008 0.692 ±0.008 0.678 ±0.002 enterobacter sp. 0.457 ±0.007 0.476 ±0.008 0.467 ±0.011 e. ludwigii 0.397 ±0.005 0.393 ±0.008 0.386 ±0.003 8-10 b. cereus 0.789 ±0.008 0.756 ±0.008 0.765 ±0.002 enterobacter sp. 0.687±0.007 0.692 ±0.008 0.674 ±0.011 e. ludwigii 0.495 ±0.005 0.512 ±0.008 0.525 ±0.003 10-12 b. cereus 0.105 ±0.008 0.108±0.008 0.111±0.002 enterobacter sp. 0.079±0.007 0.083 ±0.008 0.087 ±0.011 e. ludwigii 0.503 ±0.005 0.512 ±0.008 0.499 ±0.003 12-14 b. cereus 0.105 ±0.008 0.102±0.008 0.107±0.002 enterobacter sp. 0.078±0.007 0.069 ±0.008 0.083 ±0.011 e. ludwigii 0.072 ±0.005 0.083 ±0.008 0.082 ±0.003 (b) enterobacter sp. 0 2 4 6 8 10 12 0 2 4 6 8 10 12 14 c r u d e o il c o n c e n tr a ti o n (g /m l) × 1 0 3 incubation time (days) (a) b. cereus (c) e. ludwigii figure 3: degradation of crude oil (0.01 g/ml) by bacteria in the presence of nitrate. (a) b. cereus (b) enterobacter sp. (c) e. ludwigii; 1.0 ppm (black square), 0.1 ppm (open square) and 2.5 ppm (close circle). 20 table 3: degradation rates of crude oil by bacteria in the presence of nitrate. incubation time (days) bacteria degradation rate (day -1 ) control 0.1 ppm 2.5 ppm 0-2 b. cereus 0.742 ±0.008 0.738 ±0.008 0.749 ±0.002 enterobacter sp. 0.654 ±0.007 0.664 ±0.008 0.672±0.011 e. ludwigii 0.572 ±0.005 0.578 ±0.008 0.583 ±0.003 2-4 b. cereus 0.603 ±0.008 0.598 ±0.008 0.612 ±0.002 enterobacter sp. 0.575 ±0.007 0.583 ±0.008 0.585 ±0.011 e. ludwigii 0.323 ±0.005 0.357 ±0.008 0.378 ±0.003 4-6 b. cereus 0.597 ±0.008 0.621 ±0.008 0.632 ±0.002 enterobacter sp. 0.632 ±0.007 0.648 ±0.008 0.663 ±0.011 e. ludwigii 0.356 ±0.005 0.392 ±0.008 0.401 ±0.003 6-8 b. cereus 0.595 ±0.008 0.626 ±0.008 0.628 ±0.002 enterobacter sp. 0.432 ±0.007 0.412 ±0.008 0.441 ±0.011 e. ludwigii 0.345 ±0.005 0.357 ±0.008 0.489 ±0.003 8-10 b. cereus 0.621 ±0.008 0.791 ±0.008 0.845 ±0.002 enterobacter sp. 0.689 ±0.007 0.698 ±0.008 0.732 ±0.011 e. ludwigii 0.534 ±0.005 0.567 ±0.008 0.592 ±0.003 10-12 b. cereus 0.374 ±0.008 0.432 ±0.008 0.692 ±0.002 enterobacter sp. 0.112 ±0.007 0.231 ±0.008 0.541 ±0.011 e. ludwigii 0.521 ±0.005 0.572 ±0.008 0.579 ±0.003 12-14 b. cereus 0.015 ±0.008 0.132±0.008 0.147±0.002 enterobacter sp. 0.079±0.007 0.081 ±0.008 0.083 ±0.011 e. ludwigii 0.071 ±0.005 0.076 ±0.008 0.082 ±0.003 a rapid degradation of crude oil was recorded by all three strains at 14 days of incubation with the increase of nitrate concentration in the medium from 0.1 to 2.5 ppm. crude oil degradation percentage for b. cereus increased from 80% to 98% where enterobacter sp. from 73% to 90% and in e. ludwigii from 70% to 83% respectively (figure 3). out of two nitrate concentrations, 2.5 ppm proved to be the most potent nitrate concentration which seems accelerates bacterial growth. the degradation rate of b. cereus gradually decreased from 0.749±0.05 to 0.628±0.03 d -1 during 0-8 days of incubation and thereafter increased rapidly to 0.845 d -1 during 8-10 days when medium contain 2.5 ppm nitrate. the lowest degradation rate (0.147 d -1 ) by the b. cereus was showed at 12-14 of incubation. the other two bacterial strains showed lower degradation rate throughout the incubation period compare to b. cereus. at 2.5 ppm nitrate concentration, oil degradation rate of enterobacter sp. decreased from 0.672 to 0.441 d -1 during 0-8 days of incubation where more or less similar degradation rate was recorded by e. ludwigii (0.583 to 0.489 d -1 ).thereafter, degradation rate was gradually increased by enterobacter sp. (0.732d -1 ) and e. ludwigii (0.592 d -1 ) at 8-10 days of incubation and decreased again to 0.083 and 0.082 d -1 respectively for enterobacter sp., e. ludwigii at 12-14 days of incubation. liyanage & manage /journal of tropical forestry and environment vol. 5. no 02 (2015) 13-25 21 0 2 4 6 8 10 12 0 2 4 6 8 10 12 14 c r u d e o il c o n c e n tr a ti o n ( g /m l) × 1 0 -3 incubation time (days) 3.3 effect of ph on degradation of crude oil bacteria isolates employed in the present study showed different degradation rates in different ph. the highest degradation (84%) showed in acidic medium (ph 5.4) by e. ludwigii. in contrast b. cereus (94%) and enterobacter sp. (88%) showed great degradation trends along with incubation in alkaline medium (ph 8.6). the highest degradation rate (0.767 d -1 ) was detected at 0-2 days of incubation and the degradation rate was decreased from 0.534±0.03 to 0.082±0.03 d -1 during 4-14 days of incubation, where degradation rate of enterobacter sp. decreased gradually from 0.634±0.04 d -1 to 0.098±0.05 d -1 during 0-14 days when the medium was alkaline (ph= 8.6) at 33 o c (table 4). figure 4: degradation of crude oil (0.01g/ml)by the bacteria in different ph. (a) b. cereus (b) enterobacter sp.(c) e. ludwigii; ph= 5.4 (black square), ph= 8.6 (close circle) and ph=7.2 (open circle). results of the present study revealed that favourable environmental factors often lead to increase the bioremediation rate of native crude oil degrading bacteria. among the favourable factors; water temperature, nitrate and phosphate concentration and ph were considered as an essential component maintaining the balance of natural bacterial community. 0 2 4 6 8 10 12 0 2 4 6 8 10 12 14 c r u d e o il c o n c e n tr a ti o n (g /m l) × 1 0 -3 incubation time (days) (a) b. cereus (c) e. ludwigii 0 2 4 6 8 10 12 0 2 4 6 8 10 12 14 c r u d e o il c o n c e n tr a ti o n (g /m l) × 1 0 -3 incubation time(days) (c) e. ludwigii (b) enterobacter sp. 22 table 4: degradation rates of bacterial strains in different ph values. incubation time (days) bacteria degradation rate (day -1 ) 5.4 control (7.2) 8.6 0-2 b. cereus 0.232 ±0.008 0.740 ±0.008 0.767 ±0.002 enterobacter sp. 0.634 ±0.007 0.652 ±0.008 0.687 ±0.011 e. ludwigii 0.678 ±0.005 0.581 ±0.008 0.357 ±0.003 2-4 b. cereus 0.213 ±0.008 0.341 ±0.008 0.349 ±0.002 enterobacter sp. 0.342 ±0.007 0.586 ±0.008 0.678 ±0.011 e. ludwigii 0.572 ±0.005 0.564 ±0.008 0.327 ±0.003 4-6 b. cereus 0.237 ±0.008 0.225 ±0.008 0.534 ±0.002 enterobacter sp. 0.357 ±0.007 0.599 ±0.008 0.623 ±0.011 e. ludwigii 0.575 ±0.005 0.578 ±0.008 0.278 ±0.003 6-8 b. cereus 0.132 ±0.008 0.337 ±0.008 0.421 ±0.002 enterobacter sp. 0.123 ±0.007 0.215 ±0.008 0.634 ±0.011 e. ludwigii 0.583 ±0.005 0.593 ±0.008 0.221 ±0.003 8-10 b. cereus 0.098 ±0.008 0.339 ±0.008 0.419 ±0.002 enterobacter sp. 0.142 ±0.007 0.392 ±0.008 0.597 ±0.011 e. ludwigii 0.457 ±0.005 0.393 ±0.008 0.189 ±0.003 10-12 b. cereus 0.087 ±0.008 0.338 ±0.008 0.415 ±0.002 enterobacter sp. 0.156 ±0.007 0.387 ±0.008 0.512 ±0.011 e. ludwigii 0.323 ±0.005 0.393 ±0.008 0.106 ±0.003 12-14 b. cereus 0.085 ±0.008 0.079±0.008 0.082 ±0.002 enterobacter sp. 0.134 ±0.007 0.102 ±0.008 0.098 ±0.011 e. ludwigii 0.066 ±0.005 0.077 ±0.008 0.057 ±0.003 4. discussion sri lanka is exposed as the worst polluter of the indian ocean (nceas, 2012) and the irresponsible use of land practices, dumping oil waste to the sea, shipping activities are enhanced the contamination load of hydrocarbons, inorganic chemicals in the indian ocean (mepa, 2012). therefore, the sites where the bacterial strains were isolated are more vulnerable to oil contamination with massive shipping activity and improper practices. recently national and international agencies have received greater attention on oil pollutant status of sea and bioremediation application was suggested as an effective and eco-friendly solution (mace, 2012). a limited number of research has been carried out up to date on microbial degradation of crude oil. recent time, the contamination of crude oil in coastal area is becoming a problem and poses a potential threat to human health as well. thus, application of microbes to remediate oil is important as natural method (thavasi et al., 2011; hassanshahian et al., 2012). liyanage and manage, (2014) reported isolation and characterization of oil degrading bacteria from coastal zone in sri lanka as a first report, and the present study was aimed to optimize the environmental factors that effect on the bacterial isolates. bioremediation processes are governed by some environmental factors such as type and amount of crude oil present in the environment, environmental temperature, nutrients such as no 3, po4 3, ph, aeration, water acidity, type and population density of hydrocarbon degrading microorganisms and contaminant mobility (dragun, 1998; mace, 2012). leahy and colwell, (1990) reported the degradation liyanage & manage /journal of tropical forestry and environment vol. 5. no 02 (2015) 13-25 23 of hydrocarbon reached 29.8% after 3 days of treatment at 30 o c, whereas at 20 o c, the degradation of tph (total petroleum hydrocarbon) reached only 7%. this indicates that bacteria prefer higher temperatures, which enhance bacteria growth, following accelerates bioremediation. in the present study, at 23°c, all strains showed low degradation of crude oil and pronounced degradation was detected with increase temperature at 33 0 c for all the bacterial strains. however, alberty (2011) recorded that when temperature increases higher than 33 °c was resulted a decreasing degradation ability of bacterial strains. it is likely that at high temperatures, bacterial cells are unable to produce crude oil degrading enzymes which may result slow degradation rates (amer et al., 2014). the studies carried out by zaccone et al., (2002) have clearly described the effect of seasonal variance of nutrients in water which enhance the metabolic activities of heterotrophic bacteria. odu, (1978) documented that, after 12 weeks of incubation oil degradation by bacteria was not significantly increased in the media which was treated with phosphate. similar results were obtained from the present study as the degradation of oil by the bacterium was not significant when the media was supplemented with phosphate (figure 2). zahra and alireza, (2005) documented that nh4no3 is the best nitrogen source which maximize the degradation of oil by bacteria. results of the present study also showed that increasing of nitrate concentration in the medium from 0.1 to 2.5 ppm, enhance the oil degradation by all bacterial species (figure 3). ronald, (1996) documented that phosphate concentration on oil degradation is less effective compare with nitrogen. the analysis of the effect of phosphate and nitrate concentrations on crude oil degradation percentage showed that phosphate concentration does not have a potent on removal of crude oil where nitrate performs a major role on degradation process; through the degradation rate was subjected to fluctuation (figure 3 and figure 4). biochemical reactions of microorganisms are catalysed by enzymes (zahra and alireza, 2012) and it is well known fact that enzymatic reactions occur within a suitable ph range for microorganisms which are sensitive to alterations of ph (zahra and alireza, 2012; ron and rosernberg, 2014). results of the present study also revealed that all the bacteria isolates except e. ludwigii showed the highest degradation when the medium was alkaline (ph=8.6) (figure 4) where similar condition was recorded by diaz-ramirez et al., (2013) for degradation of oil by the bacillus sp. in alkaline media as well. thus, the results of the present study showed the effect of ph is one of the limiting factors for bio stimulation which enhance the bacterial bio remediation process in the natural environment. in addition to the results revealed that favourable environmental factors often lead to increase the bioremediation rate of native crude oil degrading bacteria. further researches in this field can result in the development of most efficient and less time consuming microbial technologies which are important for developing country like sri lanka as accelerated development has lounged international shipping harbours and fishing harbours along the coast of the country. put in harnessing microbes to degradation of petroleum became world interest and scientists are being established soon remediation methods efficient, economic, versatile and environmentally sound treatment to remove hydrocarbons form the contaminated environment. the results of the present study have showed that the bacterium b. cereus, enterobacter sp. and e. ludwigii can be used as microbial agents to remove crude oil from contamination sites of the environment and temperature, ph and nitrate concentrations are critically effect on natural oil degradation process in the environment. acknowledgement authors acknowledge the financial assistance of university of sri jayewardenepura. 24 references amer, r., el-gendy, n. s., taha, t., farag, s. and adel fattah, y. 2014. biodegradation of crude oil and its kinetics using indigenous bacterial consortium isolated from contaminated area in egyptian mediterranean ecosystem. jokull journal, 64(4): 42-52. alvarez. p.j.j., anid. p.j. and vogel, t.m. 1991. kinetics of aerobic biodegradation of benzene and toluene in sandy aquifer material. biodegradation, 2: 43-51. boopathy. r. (2000) factors limiting bioremediation technology. bioresource technology. 74: 63-67. bouwer. e.j. and zehner. a.j.b. 1993. bioremediation of organic compounds; putting microbial metabolism to work. trends biotechnology, 11: 360-367. chin. k.j., sharma. m.l., russel. l.a. and lovely, d.r. 2008. quantifying expression of a dissimilatory (bi) sulphite reductase gene in petroleum-contaminated marine harbour sediments. microbial ecology, 55: 489-499. dragun. j. 1998. the soil chemistry of hazardous materials. 2 nd edition. amherst scientific publisher, amherst. ma. efsun. d., fatma. o.t. and huseyin. s.b. 2013. bioremediation of petroleum contaminated soil. biological environmental science, 7: 39-47. farshid. k., sara. r. and yaghoob. t. 2011. evaluation of bioremediation of naphthalene using native bacteria isolated from oil contaminated soils in iran. biological research, 6: 610-616. gibb. a., chu. r., wong. k. and goodman. r.h. 2001. bioremediation kinetics of crude oil at 5 0 c. environmental engineering, 127(a): 818-824. hanson. k.g., nigam. a. and kapadia. m. 1997. bioremediation of crude oil contamination with acinetobactersp. microbiology, 35. 191-193. hassanshahian, m., mehdi, g., and cappello, s. 2012. "isolation and characterization of crude-oildegrading bacteria from the persian gulf and the caspian sea. marine pollution bulletin, 64.1: 7-12. itopf. (2012).www.itopf.com/information-services/date-and-statistics/ statistics/#top. [accessed 05 august 2015]. joel. e.k., prakash. o., will. a. and stefan. j. 2011. hydrocarbon degrading bacteria and the bacterial community response in gulf of mexico beach sands impacted by the deep water horizon oil spill. applied and environmental microbiology, 77: 7962-7974. kishore. d. and ashisk. m. 2007. crude petroleum oil biodegradation efficiency of bacillus subtilis and pseudomonas aeruginosa strains isolated from a petroleum contaminated soil. bioresource technology, 98(7): 1339-1345. kim. s.j., choi. d.h. and sim. d.s. 2005. evaluation of bioremediation effectiveness on crude oil contaminated sand. chemosphere, 59: 845-852. leahy. j.g. and colwell. r.r. 1990. microbial degradation of hydrocarbons in the environment. microbiology and molecular biology reviews, 54: 305-315. liyanage. y. and manage. p.m. 2014. isolation and characterisation of oil degrading bacteria from coastal water and sediments, 19 th international forestry and environment symposium proceeding, university of sri jayewardenepura, sri lanka, pp 129. liyanage & manage /journal of tropical forestry and environment vol. 5. no 02 (2015) 13-25 25 mace. g.b. 2012. ecological impacts of the deep water horizon oil spill; implications for immunotoxicity. toxicologic pathology, 40: 315-320. manage. p.m., christine e., linda. and lawton, a. 2009. biodegradation of microcystin –lr by natural bacterial population. applied environmental microbiology, 75(21): 5928-5932. manage. p.m., zen’ichiro. k. and shin-ichi. 2000. algicidal effect of the bacterium alcaligenes denitrification on microcystis spp. aquatic microbial ecology, 22: 111-117. nceas. 2012 available at:www.nceas.ucsb.edu/product. [accessed 05 august 2015]. mepa. 2012. oil spill events. www.mepa.gov.lk/web/index.php? option=com_content&view =article&id=56&itemid. [accessed 12 august 2015]. widdel. f. and rabus. r. 2001. anaerobic biodegradation of saturated and aromatic hydrocarbons. current opinion in biotechnology, 12: 259-276. omatayo. a.e., ojo. o.y. and amund. o.o. 2012. crude oil degradation by microorganisms in soil composts. microbiology, 7: 209-218. prince. r.c., clark. j.r. and lee. k. 2002. bioremediation effectiveness; removing hydrocarbons while minimizing environmental impacts. 9 th international petroleum environmental conference. ipec. albuquerque. nm. ronald. m. atlas. 1996. petroleum biodegradation and oil spill bioremediation. oceanographic literature review, 43(6): 351-357. ron, e.z. and rosenberg, e. 2014. enhanced bioremediation of oil spills in the sea. current opinion in botechnology, 27: 191-194. santos. h.f., carmo. f.l., paes. j.e., rosado. a.s. and pexioto, r.s. 2011. bioremediation of mangroves impacted by petroleum. water, air and soil pollution, 216. 329-350. thavasi, r., singaram j. and ibrahim m. b. 2011. application of biosurfactant produced from peanut oil cake by lactobacillus delbrueckii in biodegradation of crude oil. bioresource technology, 1023: 3366-3372. trindade. p., sobral. l.g., rizzo. a.c., leite. s.g.f. and lemos. l.s. 2002. evaluation of the biostimulation and bioaugmentation techniques in the bioremediation process of petroleum hydrocarbon contaminated soils. 9 th international petroleum environmental conference. ipec. albuquerque. nm. toone. e., winde. h., steffan. r.j. and ramos, j.l. 2013. environmental biotechnology. current opinion in biotechnology, 24: 367-549. xiaojun. li., peijun. li., xin. lin., chungui. z. and qi, l. 2008. biodegradation of aged polycyclic aromatic hydrocarbons by microbial consortia in soil and slurry phases. hazardous materials, 150. 21-26. zahra. y. and alireza. f. 2012. survey effect of ph on isolated petroleum degrading bacteria. agriculture; research and review, 2(5): 652-65. the modeling of above ground biomass in ranges of corbett tiger reserve using dual-polarization alos palsar data y. kumar * , s. singh and r.s. chatterjee indian institute of remote sensing, dehradun, india date received: 05-10-2017 date accepted: 07-12-2017 abstract the study has been carried out in the pauri garhwal district of uttarakh and keeping the focus on corbett tiger reserve (ctr). the total area of ctr covered in the scene is 889 sq. km. the main aim of the paper is to develop a model by establishing a relationship between backscatter coefficients generated from dual polarization l-band alos palsar data acquired in july 2008 and the field inventory data collected by forest survey of india team in 2010. a total of 120 sample plots data were collected in the area out of which 60 plots were used for the training of the model and the remaining 60 plots were left for the validation of the most significant model. the simple regression analysis was computed between hh & hv backscatter as independent variable and per plot biomass as dependent variable. the linear, logarithmic and polynomial best fit regression models were analyzed. it was found that the coefficient of determination is more with hv backscatter (r 2 =0.75) using logarithmic model as compared among hv in linear and polynomial on one hand and hh in linear, logarithmic and polynomial on the other hand. to improve the accuracy and to know the combined effects of both the polarizations, multiple linear regression analysis (mlr) was applied. there was a significant improvement in correlation coefficients (r 2 =0.86). the in-situ field inventory data shows that the biomass in the ctr ranges from 9.6 t/ha to 322.6 t/ha. the simple regression modelled biomass ranges from 26.2 t/ha to 401.43 t/ha, whereas the mlr modelled biomass ranges from 10.96 t/ha to 312.64 t/ha. the majority of the area was found to be in the range of 100 t/ha to 150 t/ha biomass. the coefficient of determination (r 2 ) between observed and predicted biomass was found to be 0.734 with simple regression, whereas it was found to be 0.83 with mlr. key words: biomass, modeling and remote sensing 1. introduction in the regulation of global climate change “forests” play a key role. it retains large amount of carbon over a long period and thus acts as both sink and source of carbon dioxide (co2). the estimation and monitoring of co2 source and sink are required for the greenhouse gas inventories, terrestrial carbon accounting and modelling climate change (dobson et al., 1992; falkowski et al., 2000; schimel et al., 2001; canadell et al., 2004; houghton, 2005; schulze, 2006; heimann and reichstein, 2008; le quere et al., 2009; loarie et al., 2009). approximately 50% of the carbon is stored in biomass, thus continuous and effective monitoring is required to estimate the vegetation biomass especially in forest ecosystem. * correspondence: yogesh.iirs@gmail.com tel: issn 2235-9370 print/issn 2235-9362 online © university of sri jayewardenepura 108 mailto:yogesh.iirs@gmail.com kumar et al. /journal of tropical forestry and environment vol. 7, no. 02 (2017) 108-120 the forest ecosystem is changing; the rate of change, growth and addition of biomass should be carefully understood to develop a more accurate methodology for the estimation of factors responsible for change. the destruction in the forest ecosystem leads to the emission of co2 and other greenhouse gases which results in climate change. the climate change will result in large shifts in the distribution of forest biomes which in turn will significantly change the amounts and patterns of carbon storage in these ecosystems. the mapping and to understand the pattern of change in the forest above ground biomass (agb) and carbon is an important and challenging task to perform. in earlier days destructive method was adopted which was also known as the harvest method (goetz et al., 2009; malhi et al., 2004). according to gibbs et al (2007) this method was the most direct method for the estimation of above ground biomass and the carbon stocks stored in the forest ecosystem. this method is used for development of location and species-specific allometric equations used for accessing biomass on large scale. the allometric method (chave et al., 2005; fao, 1997; ipcc, 2006) is based on the principle that every components of trees shows relationship with each other. it is a non-destructive method for the estimation of biomass without felling and thus widely used. in the forest inventories different biometric parameters of trees like diameter at breast height, circumference at breast height (cbh), height, wood density, crown diameter etc. are measured and used to establish an allometric equation by establishing the relationship between these parameters with above ground biomass. in india biomass, carbon stock and carbon budget estimation is done by various workers (ravindranath et al., 1997; lal and singh, 2000; chhabra et al., 2002) on the basis of growing stock (gs) volume data of forest inventories and appropriate conversion factor related to both biomass and carbon. remote sensing data are playing an important role in biomass assessment. an approach for the assessment of forest biomass and carbon is boosting day by day using remote sensing technology. as the biomass or carbon cannot be measured directly from remote sensing sensors, it needs the in-situ ground inventory data for establishing a relationship between the biomass and sensor signals (rosenqvist et al., 2003). the optical remote sensing data was widely used for the mapping and modelling of agb by establishing a relationship between spectral responses or vegetation indices derived from multispectral image and plot level biomass. the optical remote sensing has limited capacity to predict the accurate biomass because of low saturation level of the spectral bands and the derived spectral indices which results in poor correlation between spectral indices and biomass. the frequent cloud cover in the tropical region hindered the acquisition of high quality data in all weather conditions. from the last two decades the focus has changed from optical data to sar data for the assessment. the main advantage of sar data is its all weather and night availability with longer wavelength and deeper penetration depth, greater sensitivity to biomass and availability of data (santoro et al., 2006; santoro et al., 2009; morel et al., 2011). the sar data have been used numerously by scientists to estimate the retrieval of biomass using radar data and variations in the forest ecosystem biomass (sader, 1987; wu, 1987; hussain et al., 1991; dobson et al., 1992; kasischke, 1992; le toan et al., 1992; kasischke et al., 1994a). the longer wavelength of sar data (l and p bands) proves to be more useful than shorter wavelengths (x and c bands) because of increasing backscatter range. the strength of the relationship depends on the size of the sample plots (mitchard et al., 2009; saatchi et al., 2011) and hence should be carefully chosen and laid. the simplest approach of biomass modelling is used in the upper stretches of ctr i.e. the backscattering coefficient derived from the data is correlated with the field inventory data. this approach has been tested throughout different forest types in the world with high degree of correlation between observed and predicted forest biomass (hussein et al., 1991; le toan et al., 1992; dobson et al., 1992). the 109 potential of l-band radar backscatter to estimate aboveground biomass (agb) has been studied for most forest types (harrell et al., 1995; imhoff, 1995; kasischke et al., 1995; le toan et al., 1992; lucas et al., 2010; pulliainen et al., 1996; santoro et al., 2006). the saturation of the sar data is one of the challenge in the biomass modelling. the reported saturation level for the l-band data ranges between 40 t/ha (luckman et al., 1997; imhoff, 1995) to 150 t/ha (kuplich et al., 2005; lucas et al., 2007; mitchard et al., 2009). the saturation level for biomass in x and c band is very low (30 t/ha to 50 t/ha). remote sensing, being an advanced technology is quite useful for reliable estimation of vegetation biomass and carbon over large areas. furthermore, remote sensing is also useful for stratification of forests and in selection of proper sample plots for enumeration which is otherwise not possible through convention methods. most of the studies with optical sensors have estimated biomass indirectly because of the several inherent limitations of optical data such as: inability to penetrate the vegetation canopy, insufficient sensitivity to forest structure and above ground biomass, inadequate temporal frequency because of persistent cloud cover etc. it is proposed to evolve methods to improve the assessment of phytomass/carbon using optical and microwave remote sensing data and suggest method for improvements in estimates of biomass. taking the advantage of the deeper penetration of longer wavelength in the forest canopy, an attempt was made to develop empirical relationships between microwave backscatter from satellite and the biomass levels so as to estimate the forest biomass of the study area. the significant empirical relationship was used for the spectral modelling of biomass in the whole study area. 2. materials and methods 2.1. the study area the corbett tiger reserve lies between the latitudes 29 o 25' n to 29 o 40'n & longitudes 78 o 5' e to 79 o 5' e. it spreads through 3 districts of uttarakhand namely pauri, nainital, almora and a small part falls in amangarh, bijnore district of eastern uttar pradesh. the ramganga, palain and sonanadi river flow through these valleys. the vegetation in ctr is of forests, grasslands and riparian types. floral diversity of ctr is very rich as the major portion of the reserve is confined to bhabar tract of shiwalik formation. there are 617 species of the flora under 410 genera 111 families of angiosperms (monocot-132, dicots-462), 1 gymnosperm and 22 fern and fern allies. there are more than 110 tree species in the forest. notably 73% is constituted by sal (shorea robusta) forests. a frequent associate of sal is adina cordifolia. the predominant species in the higher ridges is bakli (anogiesus latifolia) and the other associates are bauhinia rausinosa), lagerstromia parviflora, cassia fistula, semecarpus anacardium. chir (pinus roxburghii) the only conifer is confined to some of the highest ridges around sultan. the river valley, high banks and islands are dominated by delbergia sissoo. lantana camara is profusely invading in the reserve, inhibiting the growth of other species. cannabis sativa is also found extensively in the grasslands. 2.2. satellite data the phased array type l-band synthetic aperture radar (palsar) is an active microwave sensorusing l-band frequency to achieve cloud-free and day-and-night land observation. alos palsar fine beam dual polarization (fbd) scene was obtained from the alaska satellite facility. the data of july 2008 was downloaded which consists of two bands in hh and hv polarization having spatial resolution of 15.85 m. 110 kumar et al. /journal of tropical forestry and environment vol. 7, no. 02 (2017) 108-120 figure 1: plot locations for field data inventory. 2.3. field data collection a two stage sampling design is formulated for national forest inventory. in the first stage the country is divided into homogeneous strata based on physiography, climate and vegetation. samples of 10 percent districts proportion to their sizes are selected randomly for the detailed inventory. for each selected districts, survey of india (soi) topo sheets of 1:50,000 scales (size 15’×15’) are divided into 36 grids of 21/2’×21/2’ which is further divided into sub-grids of 11/4’×11/4’ forming the basic sampling frame. two of these sub-grids are then randomly selected to lay out the sample plots. the sample plot of size 31.62×31.62m was laid and the diameter at breast height (dbh) of all tress having dbh 10cm and above using caliper, double bark thickness using 6 2 steel scale, height of the tress using hypsometer and crown width were measured and recorded. the sample plot is divided into sub-sample plots of 5×5m for herbs and 1×1m for shrubs. 2.4. plot level biomass the allometric equations developed by forest survey of india (1996) were used. the data base of the field data was created in the ms excel sheet and analyzed in spss software. the circumferences at breast height were converted into diameter and basal area was calculated. the volume of each tree within the plot was estimated using aforementioned allometric relationship. the selection of volume equation for a species depends upon the ‘n’ (total number of sample tree on which regression equation are based) and ‘r 2 ’ (coefficient of determination). the value obtained from the equation was multiplied with wood specific gravity (forest research institute, 1996) to estimate the biomass. = × the total biomass of all the trees within the plot were obtained by multiplying the obtained biomass with biomass expansion factor (bef) and the oven dry weight of shrubs, herbs and litters were all added to get the plot level biomass which was further taken on to pixel level biomass. 111 2.5. image processing the dual polarization alos palsar data acquired is imbedded with inherent speckle noise which reduces the appearance of data. multilook operator was used to reduce the inherent speckle and to get a nominal image pixel size. the terrain correction was carried out using 30m resolution srtm dem obtained usgs earth explorer in asf tool of polsar-pro followed by speckle filtering. the data was provided with the digital numbers (dn) which was converted in to backscattering coefficient using the formula: °[ ] = 10 10( )2 + shimada, et al. , 2009 where: cf = -83 [db] the formula was applied on both the hh and hv polarizations to get backscattered images. the backscattering coefficients values were different for both the polarizations. the range boundaries of the corbett tiger reserve were used in arc-gis to extract the area falls under the reserve. the sampling was done for the whole region to reduce the uncertainty in the modelling. 2.5.2. biomass modelling and mapping the global positioning system (gps) locations of the sample plots were converted into point shape using arc gis software. half of the sample plot information was used for the training of models for the assessment of biomass and the remaining half was used for the validation of the model. the plot information used for the training was overlaid on back scattered image of hh and hv polarizations. the sigma naught (σ o ) backscattering coefficient values were extracted from the plots. the backscattered values for both the polarizations were correlated with the plot level biomass. the best fit model was selected for the modelling of biomass in the corbett tiger reserve. 3. results and discussion 3.1. plot level biomass the destructive methodology has been preceded by non-destructive methodology for biomass estimation. the plot level basal area was taken as variable for the estimation of biomass. a significant coefficient of correlation (r 2 =0.94) was found between the basal area and biomass in 120 sample plots. the biomass in the region ranges between 10.12 t/ha and 322.61 t/ha. the majority of the area was found to be in the range of 100 t/ha to 150 t/ha biomass. the possible explanation for significant degree of determination might be related to the fact that this region is a protected area in which periodic silvicultural practices has been applied for its management. 3.2. biomass modelling and estimation the satellite image was extracted for the ranges lies within corbett tiger reserve. the aim was to estimate the biomass in the tiger reserve, thus the remaining regions were not used in the modelling. the figure 3 & 4 shown below are the backscatter image of both the polarizations falls within the tiger reserve. the backscattering coefficients for the field plots ranged from -31.52 to 12.75 db in hv polarization (figure 3) whereas it ranges from -26.76 to 16.64 db in hh polarization (figure 4). the hv backscatter was observed to be less as compared with hh polarization. 112 kumar et al. /journal of tropical forestry and environment vol. 7, no. 02 (2017) 108-120 the less value of hv polarization is due to its multiple interactions with the forest canopy as compared with hh polarization. the less negative values and higher positive values were discarded before setting up the relationship. figure 3: hv backscatter image of alos figure 4: hh backscatter image of palsar alos palsar the biomass values were to be predicted (dependent variable) on the basis of backscatter coefficients (independent variable). thus, simple regression analysis was performed for the analysis. the plot level biomass were plotted on the y-axis and the backscatter values were plotted on the x-axis to obtain scatter plot. the best fit regression models were tried on the data sets. the linear best fit regression line between plot level biomass and hv and hh backscatter are shown in figure 5a & 5b. the coefficient of determination is more with hv backscatter (r 2 =0.75). it shows that 75% variability in the biomass can be addressed by hv backscatter. it was found low with hh backscatter (r 2 =0.45). similarly, the logarithmic best fit regression line was applied with both the polarizations. it was found that the logarithmic regression provides the best regression model with hv polarization having a highest coefficient of determination (r 2 =0.754) with respect to hh (r 2 =0.48) polarization (figure 5c & 5d). polynomial equation was considered to be least significant among other equations for the modelling. the figure 5e and 5f represents its regression with hv and hh polarization. the coefficient of determination (r 2 ) was observed to be 0.73 with hv backscatter and 0.48 with hh polarization. it was observed from the graphs that the regression lines were saturating when the range of biomass crosses 150 t/ha. the regression graphs are shown below in figure 5. 113 0 y = 0.5564x 19.758 -5 r² = 0.7508 ba ck sc at te r -10 h v σ -15 -20 -25 0 5 10 15 20 25 biomass t/0.1ha 5a. linear relationship between hv and plot biomass y = 4.8561ln(x) 24.796 0 r² = 0.7543 -5 b a c k s c a t t e r -10 -15 h v σ -20 -25 0 5 10 15 20 25 biomass t/0.1ha 5c. logarithmic relationship between hv and plot biomass y = -0.0153x2 + 0.8901x 21.212 0 r² = 0.7386 -5 backscatter -10 -15 h v σ -20 -25 0 5 10 15 20 25 biomass t/0.1ha 5e. polynomial relationship between hv and plot biomass 0 y = 0.5003x 13.672 -2 r² = 0.4482 -4 backsccater10 -6 -8 σ -12 h h -14 -16 -18 0 5 10 15 20 25 biomass t/0.1ha 5b. linear relationship between hh and plot biomass y = 4.1071ln(x) 17.746 0 r² = 0.4814 -2 σb ac ks cc at er -4 -6 -8 -10 -12 hh-14 -16 -18 0 5 10 15 20 25 biomass t/0.1ha 5d. logarithmic relationship between hh and plot biomass 0 y = -0.0319x 2 + 1.1146x 16.107 r² = 0.4862 -2 -4 backsccater10 -6 -8 σ -12 h h -14 -16 -18 0 5 10 15 20 25 biomass t/0.1ha 5f. polynomial relationship between hh and plot biomass figure 5: regression graphs 114 kumar et al. /journal of tropical forestry and environment vol. 7, no. 02 (2017) 108-120 among different curve progression (linear, logarithmic, polynomial) of correlation the optimal equation with high coefficient of determination (r 2 =0.75) was derived from hv backscatter in logarithmic model when used independently and was found to be: = 4.8561 ln − 24.796 (1) where: y=backscatter coefficient (σ 0 [db]) x = biomass the results were compared with the studies carried out on the similar principle across the world. it was found that the backscatter from the forests depends on the structural properties (imhoff, 1995a). it has been demonstrated that there is a strong relationship between backscatter coefficients and above ground biomass within a particular forest types (le toan et al., 1992; dobson et al., 1992; imhoff, 1995b). a model based approach had been investigated for stem wise forest stem volume retrieval using jers-1 l-band sar data in sweden, finland and siberia. in dense forest the backscatter shows a difference of ~4db, whereas in sparse forests, the backscatter depends on the dielectric properties of the forest floor showing smaller difference throughout the year (santoro et al., 2006). a similar study had been conducted by luckman et al., (1997) in the central amazon basin using ers-1 & jers-1 satellite. it was concluded that the longer wavelength (l-band) is more suitable to discriminate between different levels of forest biomass up to a certain threshold because of its deeper penetration into the vegetation canopy. the cross polarized backscatter is more sensitive to changes in biomass density because of its crown scattering mechanism. in the case with shorter wavelength (c-band), it has been difficult to differentiate between vegetation and bare soil when it is dry. in the simple regression analysis only one independent variable was used for the prediction of biomass in the region. to improve the accuracy and to know the combined effects of both the polarizations, multiple regression analysis was applied. the multi-linear regression analysis has been done using plot level biomass as dependent variable and hh & hv polarizations as independent variables. there was a significant improvement in correlation coefficients (r 2 =0.86). the equation developed using multi-linear regression analysis was found to be: = 1.364 − 0.098 + 28.20 (2) this equation 2 obtained from independent hv backscatter and biomass using logarithmic model and the equation 3 obtained from mlr analysis were used for above ground biomass mapping in ctr. both the models were run independently to predict the biomass from plot level to the whole study area. the modelled biomass using equation 2 varies from 26.2 t/ha to 401.43 t/ha. the modelled biomass using equation 3 varies from 10.96 t/ha to 312.64 t/ha. the predicted biomass range using equation 3 was very close with the field data because of the combined potential of both the polarization. a simple approach to evaluate the model is to regress predicted verses observed values. thus, the biomass maps obtained through the modelling using both the equations 2 & 3 were plotted against the remaining in-situ plot biomass (60 sample plots) left for the validation of the model. the observed plot biomass was represented on x-axis and the predicted biomass was represented on y-axis. a significant coefficient of determination (r 2 =0.734) is obtained between observed biomass and predicted biomass in case of values predicted by single regression analysis 115 using hv backscatter (fig 6). whereas, a strong coefficient of determination has been observed with multiple linear regression based biomass map and in-situ data (r 2 =0.83) (figure 7). the total of 83% variability can be addressed by observed value to explain predicted values using mlr based equations whereas only 73.4% variability can be addressed using simple regression model. the result explains that both the parameters are essential for the estimation of biomass using microwave data. the figure 8 represents the biomass distribution map in the ranges of corbett tiger reserve. the map clearly shows the majority of the area is dominated with the biomass range between 100 t/ha to 150 t/ha. it was observed during the field visit that few regions which were showing high biomass region i.e. more than 200 t/ha was actually not existing. the reason for this overestimation was due to the topographic distortion of layover and foreshortening in the sar image. this topographic effect can be reduced by using different incidence angle sar images in both the ascending and descending mode. the accuracy of the model can further be improved by utilizing the capabilities of fully polarimetric data. the semi-emperical models such as water cloud model (wcm), extended water cloud model (ewcm) will have the capabilities to improve the biomass estimation in the region. the launch of nisar mission in 2020 is going to be a great opportunity for mapping the biomass and carbon stock all across the country with a reliable and accurate means. figure 6: observed vs predicted figure 7: observed vs predicted biomass using mlr. 116 kumar et al. /journal of tropical forestry and environment vol. 7, no. 02 (2017) 108-120 figure 8: distribution of biomass in ctr. 4. conclusions the potential of l-band alos palsar dual polarization data has been investigated for the biomass retrieval in the ctr. the l-band alos palsar data is proved to be sensitive to the differences in the biomass and thus very useful in the agb mapping in ctr. the simple regression analysis and multi-linear regression have been tried for biomass mapping in ctr. the best correlated model is derived from the relationship between backscatter coefficient of alos palsar and plot level biomass. among the two polarizations hh & hv, hv found to be strongly correlated with plot biomass. the field inventory data shows that the biomass in the ctr ranges from 9.6 t/ha to 322.6 t/ha. the modelled biomass represents that the majority of the area is dominated with the biomass ranges from 100 t/ha to 150 t/ha. the total biomass in the upper stretches of ctr covering an area of 889 sq. km is found to be 8.9 million tonnes. a significant coefficient of determination is observed between the observed and predicted biomass on 95% confidence interval modelled using mlr. the mlr proves to be more effective for modelling as compared with slr modelling. it was observed that the sample plot should be large enough to obtain a better relationship between backscattering coefficients and agb as the area is rich in biodiversity and have complex structure of vegetation. the intensity of backscatter also gets saturated around 100 mg/ha. some uncertainties have been observed through the area having steep slopes. the layover and foreshortening were the major causes for the uncertainty. the overall accuracy of the result can further be enhanced using quad polarization data and through the technique of polarimetric decomposition. acknowledgements the work in this paper was carried out with the support of ‘forest inventory unit’ forest survey of india, dehradun. the author wishes to thank director general (dg) and assistant director general (adg) forest survey of india for valuable guidance and support. references canadell, j., ciais, p., cox, p., &heimann, m. (2004). quantifying, understanding and managing the carbon cycle in the next decades. climatic change, 67(2–3), 147–160. 117 chhabra, a.; palria, s. and dadhwal, v.k. (2002). a spatial distribution of phytomass carbon in indian forests. global change biology 8(12): 1230-1239. chave, j., andalo, c., brown, s., cairns, m. a., chambers, j. q., eamus, d., et al. (2005). tree allometry and improved estimation of carbon stocks and balance in tropical forests. oecologia, 145, 87−99. dobson, m. c., ulaby, f. t., le toan, t., kasische, e s., and christensen, n. (1992), dependence of radar baekseatter on coniferous forest biomass. ieee transaction on geoscience and remote sensing, 30(2):412-415. falkowski, p., scholes, r., boyle, e., canadell, j., canfield, d., elser, j., et al. (2000). the global carbon cycle: a test of our knowledge of earth as a system. science, 290(5490), 291–296. fao (1997). estimating biomass and biomass change of tropical forests: a primer. fao forestry paper, 134, rome, italy: food and agriculture organization (fao). gibbs, h. k., brown, s., niles, j. o., & foley, j. a. (2007). monitoring and estimating tropical forest carbon stocks: making redd a reality. environmental research letters, 2, 1−13. goetz, s. j., baccini, a., laporte, n. t., johns, t., walker, w., kellndorfer, j., et al. (2009). mapping and monitoring carbon stocks with satellite observations: a comparison of methods. carbon balance and management, 4, 1−7. harrell, p. a., bourgeau-chavez, l. l., kasischke, e. s., french, n. h. f., & christensen, n. l. (1995). sensitivity of ers-1 and jers-1 radar data to biomass and stand structure in alaskan boreal forest. remote sensing of environment, 54, 247–260. heimann, m., & reichstein, m. (2008). terrestrial ecosystem carbon dynamics and climate feedbacks. nature, 451, 289–292. houghton, r. (2005). aboveground forest biomass and the global carbon balance. global change biology, 11(6), 945–958. hussain, y.a., reich, r.m., and hoffer, r.m., 1991. estimating slash pine biomass using radar backscatter. i.e.e.e. transactions on geoscience and remote sensing, 29, 427-431. imhoff, m. l. (1995). a theoretical analysis of the effect of forest structure on synthetic aperture radar backscatter and the remote sensing of biomass. ieee transactions on geoscience and remote sensing, 33, 341–352. imhoff, m. l. (1995). radar backscatter and biomass saturation: ramifications for global biomass inventory. ieee transactions on geoscience and remote sensing, 33, 511–518. ipcc (2006). ipcc guidelines for national greenhouse gas inventories. in s. eggleston, l. buendia, k. miwa, t. ngara, & k. tanabe (eds.), japan: iges. kasischke, e. s., christensen, n. l., &bourgeau-chavez, l. l. (1995). correlating radar backscatter with components of biomass in loblolly pine forests. ieee transactions on geoscience and remote sensing, 33, 643–659. kasischke, e.s., 1992. monitoring changes in above ground biomass in loblolly pine forests using multi-channel synthetic aperture radar data. phd. dissertation. the university of michigan, ann arbor, mi 48109. 118 kumar et al. /journal of tropical forestry and environment vol. 7, no. 02 (2017) 108-120 kasischke, e.s., bourgeau-chavez, l. l., christensen, n.l.jr., and haney, e., 1994a. observation on the sensivity of ers-1 sar image intensity to change in above-ground biomass in young loblolly pine forests. international journal of remote sensing, 15, 3-16. kuplich, t. m., curran, p. j., & atkinson, p. m. (2005). relating sar image texture to the biomass of regenerating tropical forests. international journal of remote sensing, 26, 4829−4854. lal, m., and singh, r.(2000). carbon sequestration potential of indian forests. environment monitoring assessment 60:315-327. le quere, c., raupach, m., canadell, j., marland, g., bopp, l., ciais, p., et al. (2009). trends in the sources and sinks of carbon dioxide. nature geoscience, 2, 831–836. le toan, t., beandoin, a., and guyon, d. (1992), relating forest biomass to sar data, ieee trans. geosci. remotesens. 30(2):403-411. loarie, s., asner, g., & field, c. (2009). boosted carbon emissions from amazon deforestation. geophysical research letters, 36, l14810, doi:10.1029/2009gl037526. lucas, r. m., mitchell, a. l., rosenqvist, a., proisy, c., melius, a., & ticehurst, c. (2007). the potential of l-band sar for quantifying mangrove characteristics and change: case studies from the tropics. aquatic conservation—marine and freshwater ecosystems, 17, 245−264. lucas, r., armston, j., fairfax, r., fensham, r., accad, a., carreiras, j., et al. (2010). an evaluation of the alos palsar l-band backscatter — above ground biomass relationship queensland, australia: impacts of surface moisture condition and vegetation structure. ieee journal of selected topics in applied earth observation and remote sensing, 3, 576–593. luckman, a., baker, j., kuplich, t. m., yanasse, c. d. f., &frery, a. c. (1997). a study of the relationship between radar backscatter and regenerating tropical forest biomass for spaceborne sar instruments. remote sensing of environment, 60, 1−13. malhi, y. p. (2002), forests, carbon and global climate. philosophical transactions of the royal society of london a ,pp 15671591. malhi, y., baker, t. r., phillips, o. l., almeida, s., alvarez, e., arroyo, l., et al. (2004). the aboveground coarse wood productivity of 104 neotropical forest plots. global change biology, 10, 563−591. mitchard, e. t. a., saatchi, s. s., woodhouse, i. h., nangendo, g., ribeiro, n. s., williams, m., et al. (2009). using satellite radar backscatter to predict above-ground woody biomass: a consistent relationship across four different african landscapes. geophysical research letters, 36. morel, a.c., saatchi, s. s.,malhi, y., berry, n. j., banin, l., burslem, d., et al. (2011). estimating aboveground biomass in forest and oil palm plantation in sabah, malaysian borneo using alos palsar data. forest ecology and management, 262, 1786–1798. pulliainen, j. t., mikkela, p. j., hallikainen, m. t., &ikonen, j. p. (1996). seasonal dynamics of cband backscatter of boreal forests with applications to biomass and soilmoisture estimation. ieee transactions on geoscience and remote sensing, 34, 758–770. ravindranath, n.h.,somashekhar, b.s. and gadgil, m. (1997). carbon flows in indian forests. climate change 35:297-320. 119 rosenqvist, a., shimada, m., igarashi, t., watanabe, m., tadono, t., & yamamoto, h. (2003). support to multi-national environmental conventions and terrestrial carbon cycle science by alos and adeos-ii-the kyoto and carbon initiative. proceedings of 2003 ieee international on geosciences and remote sensing symposium, 3. (pp. 1471–1476). saatchi, s., marlier, m., chazdon, r. l., clark, d. b., & russell, a. e. (2011). impact of spatial variability of tropical forest structure on radar estimation of aboveground biomass. remote sensing of environment, 115(11), 2836–2849. sader, s. (1987), forest biomass, canopy structure, and species composition relationships with multipolarization l band synthetic aperture radar data. photogrammetric engineering and remote sensing , 55, pp 193–202. santoro, m., eriksson, l., askne, j., &schmullius, c. (2006). assessment of stand-wise stem volume retrieval in boreal forest from jers-1 l-band sar backscatter. international journal of remote sensing, 27, 3425–3454. santoro, m., fransson, j. e. s., eriksson, l. e. b., magnusson, m., ulander, l. m. h., & olsson, h. (2009). signatures of alos palsar l-band backscatter in swedish forest. ieee transactions on geoscience and remote sensing, 47, 4001–4019. schimel, d., house, j., hibbard, k., bousquet, p., ciais, p., peylin, p., et al. (2001). recent patterns and mechanisms of carbon exchange by terrestrial ecosystems. nature, nature, 414(6860), 169–172. schulze, e. (2006). biological control of the terrestrial carbon sink. biogeosciences, 3(2), 147–166. shimada, m., isoguchi, o., tadono, t., &isono, k. (2009). plasar radiometric calibration and geometric calibration. ieee transaction on geosciences and remote sensing, 3, 765–768. wu, s.t., 1987. potential application of multipolarization sar for pine – plantation biomass estimation. i.e.e.e. transactions on geoscience and remote sensing, 25, 403-409. 120 36 a study on the phytoremediation potential of azolla pinnata under laboratory conditions l.l.u. mandakini 1* , n.j.g.j. bandara 1 , d. gunawardana 2 1 department of forestry and environmental science, university of sri jayewardenepura, sri lanka 2 department of botany, university of sri jayewardenepura , sri lanka date received: 01-12-2015 date accepted: 10-06-2016 abstract heavy metal contamination in aquatic environments has become one of the major environmental problems all over the world. phytoremediation is a plant based technology that utilises special plants known as hyperaccumulators to purify heavy metal contaminated sites. hyperaccumulators are capable of absorbing heavy metals in greater concentrations. azolla pinnata is an aquatic macrophyte that has been earmarked for its hyperaccumulation ability. this study was conducted under laboratory conditions to assess the ability of a. pinnata for the removal of cr, ni, cd and pb through rhizofiltration. under three main experiments, phytoremediation ability of this species was investigated. in the first experiment, a. pinnata was exposed to prepared solutions of cr, ni and pb of 2 ppm, 4 ppm, 6 ppm, 8 ppm and 10 ppm and of cd solutions of 0.5 ppm, 1.0 ppm, 1.5 ppm, 2.0 ppm, 2.5 ppm and 3.0 ppm respectively. experiments were carried out separately for cr, ni, cd and pb concentrations for 7 days. presence of cr, ni, cd and pb caused a maximum inhibition of a. pinnata growth by 47%, 54%, 52% and 45% respectively while the highest removal percentages of cr-98%, ni-57%, cd88% and pb-86% were recorded in 2 ppm, 2 ppm, 0.5 ppm and 8 ppm treatments respectively. the highest bio-concentration factor (bcf) for cr was 1,376.67 when treated with 6 ppm, 684.95 at 4 ppm for ni, 1,120.06 at 0.5 ppm for cd and 1,332.53 at 8 ppm for pb respectively. at the end of the experiments toxic symptoms were observed in plants exposed to cd and ni. the findings of this experiment revealed that a. pinnata is an excellent candidate for the removal of pb and cr even at higher concentrations and for cd at lower concentrations while it is only partially efficient for ni removal. the ability of a. pinnata to remove cr, ni, cd and pb from open dump site leachate was investigated in the experiment three. a. pinnata was exposed to a leachate dilution series of 5%, 15%, 25%, 50%, 75% and 100%. for all four metals, the highest removal percentages as well as the highest bcfs were given by the plants exposed to 5% leachate concentration. influence of interactive effects of cr, cd, ni and pb on their removal capacities of a. pinnata and the metal selectivities were determined by the experiment two. the metal selectivity of a. pinnata was pb> cd> cr> ni. a. pinnata can be designated as a good phytoremediation tool for the mitigation of heavy metal pollution due to its high bcfs (over 1,000) in relation to pb (2-10 ppm), cr (2-10 ppm) and cd (0.5-1 ppm). 1 keywords: phytoremediation, azolla pinnata, heavy metals, bio concentration factor, metal accumulation * correspondence: upekhamandakini@gmail.com tel: + 94 715181704 issn 2235-9370 print/issn 2235-9362 online © university of sri jayewardenepura mandakini et al. /journal of tropical forestry and environment vol. 6. no 01 (2016) 36-49 37 1. introduction many aquatic environments are polluted by heavy metals due to a myriad of reasons including industrial effluents, leaching of heavy metals from soil or bedrock and agrochemical usage in contemporary agriculture. heavy metals are metallic chemical elements with a high atomic weight and densities five times greater than water (sood et al., 2011). many heavy metals are essential to the life cycles of both flora and fauna but are capable of reaching toxic levels when the supply of heavy metals through natural and anthropogenic sources exceeds their demand by inherent biological systems. heavy metals are considered a dangerous threat to the environment due to three key criteria, i.e. persistence, bioaccumulation and toxicity. heavy metals are non-degradable chemical residues which possess long persistence times in the environment and gradually enter food chains and accumulate within higher trophic levels, endangering both animal and human life. therefore the mitigation or attenuation of heavy metals from polluted aquatic environments is of great importance in protecting both the environment and human health. heavy metals from aquatic environments can be removed by a variety of techniques which include chemical, physical and biological techniques such as precipitation, ion exchange, chemical reduction and oxidation, membrane filtration, solvent extraction, reverse osmosis and activated carbon adsorption. however, the applications of these advanced remediation strategies are limited especially in developing countries as they are not economically feasible and require high sophisticated equipment which can be expensive to acquire. generation of secondary wastes, metal specificity and suitability only in a narrow range of concentrations, are the other major limitations of the above methods. one technology that is widely utilised for remediation of polluted environment is phytoremediation which is based on exploiting a plant’s intrinsic mechanisms to accumulate or detoxify heavy metals from the soil or from aquatic environments. phytoremediation is a low cost green technology and has been shown to be effective in diverse aquatic systems including reservoirs and ponds. certain plants known as hyperaccumulators are capable of absorbing heavy metals which have no importance for plant metabolic processes. these hyperaccumulating plants which possess the capacity to absorb non-essential heavy metals are suitable candidates for efficient phytoremediation. in hyperaccumulation, heavy metal pollutants are absorbed by the roots of the plants and are concentrated in the plant tissues or decomposed to less harmful forms. plants that can absorb and tolerate high levels of heavy metals are considered as potent candidates of phytoremediation. floating aquatic macrophytes are defined as plants that float on the water surface with submerged roots. many aquatic macrophytes are potential candidates of phytoremediation as they demonstrate strong capacities to absorb non-essential heavy metals and concentrate them in tissues (salt et al, 1995). in addition, the rapid proliferation and direct contact of aquatic macrophytes with the contaminated environment facilitates the purification process and ensures the sanitation of polluted water bodies. 38 azolla pinnata is a small free-floating aquatic fern that lives in a mutual symbiosis with a cyanobacterium (nostoc azollae), which resides within dorsal cavities of the fronds. nostoc azollae can fix atmospheric nitrogen into ammonium ions, which are a source of nitrogen to the water fern. subsequent decomposition of the water fern enriches the soil of paddy fields with nitrogen and due to its benefit as a nitrogen biofertilizer, a. pinnata is cultivated widely among rice cultivars to ensure that there is a constant supply of nitrogen to the soil. in this study, the phytoremediation potential of a, pinnata was assessed in an ex-situ tankbased experimental system, where its phytoaccumulation capacity for four heavy metals, namely chromium (cr), cadmium (cd), nickel (ni) and lead (pb). the data generated in this study showed that a. pinnata is a good phytoremediation candidate for the sequestration of cr and pb and possesses limited capacity to be an efficient phytoremediation agent for cd. 2. materials and methods 2.1 plants acquisition and acclimatization a. pinnata was obtained from paddy fields at the rice research and development institute labuduwa, galle. healthy mature plants were selected for the experiment and rinsed with tap water in order to remove adhering mud particles and epiphytes. in order to adapt to the experimental conditions and to obtain substantial biomass, those plants were grown in a plastic trays containing distilled water with albert solution for 10 days in the greenhouse of department of forestry and environmental science, university of sri jayewardenepura. 2.2 preparations of stock solutions and treatment/experiment series experiment 1 concentrations of heavy metals used in the experiments largely agreed with the environmentally measured values, although in certain experiments, higher treatments exceeded the environmental pollution levels. treatment solutions of cr, cd, ni and pb were prepared by diluting the respective stock solutions of 1,000 ppm concentration. a treatment series of 2 ppm, 4 ppm, 6 ppm, 8 ppm and 10 ppm was performed for cr, pb and ni, while a series of 0.5 ppm, 1.0 ppm, 1.5 ppm, 2.0 ppm, 2.5 ppm and 3.0 ppm was used for cd, on par with the environmental levels of the respective heavy metals. experiments for all four metal ions were carried out separately in the greenhouse at an ambient temperature of 25 c. rectangular glass aquariums with the dimensions of 28×15×10 cm were used to perform the experiment. aquariums were filled with 2 l of each treatment solution in triplicates and distilled water in the absence of the metal was used as the control. one gram of albert solution was added into each aquarium to supply the nutrient requirements and ph of the solutions were maintained between 6.5-7.5 throughout the experiment by titration with hcl and naoh. healthy and matured a. pinnata plants were selected, rinsed with distilled water and blotted on filter papers to remove adherent water and 10 g of the water fern were laid on the surface of each aquarium. all the experiments were run for a 7 day period. twenty milliliters water samples were mandakini et al. /journal of tropical forestry and environment vol. 6. no 01 (2016) 36-49 39 withdrawn from each individual replicate at 12 hour intervals. distilled water was added based on necessity, to compensate for the water loss through evaporation and transpiration. sample analysis water samples were filtered with whatmann no.1 filter papers and analysed by flame atomic absorption spectrometer (faas, gbc 932 plus) for cr, ni, cd and pb. on the 7th day of the experiment a. pinnata plants in each individual replicate were harvested, rinsed with distilled water to remove any ions adhere to plant’s surface and dried out by blotting on filter papers separately. then the fresh biomass was weighed, dried for hours in an o en at c and the dry weights were subsequently measured. dried plant biomass were digested by wet digestion method according to kalra, (1998) and analyzed by faas (gbc 932 plus) to determine the metal concentrations in a. pinnata tissues. experiment 2 the objective of this experiment was to determine the influence of the interactive/competitive effects of cr, cd, ni and pb on their removal capacities of each metal by a. pinnata. experimental design the treatment solution was prepared as a mixture of all four metals. thus, it comprised of cr, cd, ni and pb concentrations which gave the highest bio concentration factor (bcf) values in experiment 1. table 1: initial concentrations of cr, ni, cd and pb in the treatment solution. metal treatment concentrations that gave the highest bcfs in experiment 1 (ppm) cr 6.0 ni 4.0 cd 0.5 pb 8.0 same experimental conditions were maintained as in experiment 1. fifty millilitres of water samples were withdrawn from each individual replicate at 24 hours intervals and on the last day of the experiment a. pinnata plants were harvested, weighed after rinsing with distilled water and the adherent water removed using filter papers. sample analysis was also done in the same manner as experiment 1. experiment 3 sample collection leachate samples were collected from karadiyana solid waste dumpsite which is located adjacent to the bolgoda river. all samples were collected at the inlets of leachate collection drains around the dumpsite in order to obtain leachate with maximum contamination of heavy metals. leachate samples were collected in polypropylene bottles and immediately transported to the greenhouse. 40 experimental design all collected leachate samples were mixed in order to get a homogenous mixture. a concentration series of 5%, 15%, 25%, 50%, 75% and 100% were prepared by diluting the leachate and 2 l of each was filled into 28×15×10 cm sized rectangular glass containers in the form of triplicates. tap water was used as the control treatment. healthy mature a. pinnata plants were selected, rinsed with distilled water and the water removed by blotting on filter paper. ten grams of a. pinnata was introduced to each aquarium. the experiment was run for seven days at an ambient temperature of 25 c. of leachate samples were withdrawn from each individual replicate at 24 hour intervals. a. pinnata plants were harvested at the end of the experiment and fresh weights determined by removing adherent water using filter papers, following rinsing with distilled water. 2.3 atomic absorption spectrometry analysis water samples were filtered with whatmann no.1 filter papers and analysed by flame atomic absorption spectrometer (faas, gbc 932 plus) for cr, ni, cd and pb. dried plant biomass digested by wet digestion method according to kalra (1998), were also analysed by faas (gbc 932 plus) to determine the metal concentrations in a. pinnata tissues. for experiment 3, a portion of original leachate was analysed for cr, cd, ni and pb in order to determine their initial concentrations. leachate samples withdrawn at 24 hours intervals were digested according to apha, (1999) and analyzed by faas (gbc 932 plus) to determine the remaining cr, cd, ni and pb concentrations in leachate treatments. plant materials were digested and analyzed in the same manner as described above. 2.4 measurement of fresh and dried biomass on the 7 th day of the experiment a. pinnata plants in each individual replicate were har ested, rinsed with distilled water to remo e any ions adhering to plant’s surface and dried out by blotting on filter papers separately. then the fresh biomass was weighed, dried for 48 hours in an o en at c and the dry weights subsequently measured. 2.5 calculations the following parameters were calculated using the mean values of the data obtained from the experiments. relative growth the relative growth of the plants exposed to the treatment solutions were calculated using the initial fresh weights and final fresh weights of a. pinnata biomass as follows (xiaomei et al., 2004). (1) mandakini et al. /journal of tropical forestry and environment vol. 6. no 01 (2016) 36-49 41 removal efficiency the removal percentage of metal ions by a. pinnata was determined by using the initial metal concentrations of the treatment and the final concentrations at the end of the experiment (bakar et al., 2013). (2) metal uptake capacity the accumulation of metal ions in a. pinnata tissues was calculated by using the dried weights. the metal concentrations of digested biomass were calculated as follows (bediako, 2013). (3) bio concentration factor (thayapara et al., 2013) (4) 3. results 3.1 phytoremediation of chromium by azolla pinnata high removal efficiencies were observed in all treatments, with 98% (2 ppm) to 77% (10 ppm) removal efficiencies detected in the tested range (2 to 10 ppm) of cr concentrations. in all treatments, high bcfs of over 1000 were observed with the highest bcf (1376.67) recorded in the 6 ppm cr treatment. the relative growth of all cr treatments were comparatively reduced to the negative control with a relative growth value of 1.14 observed in a. pinnata plants treated with the most concentrated treatment of cr (10 ppm) (table 2). table 2: mean values of removal efficiency, relative growth, uptake and bio concentration factor (bcf) of chromium by a. pinnata. parameter control 2 ppm 4 ppm 6 ppm 8 ppm 10 ppm removal efficiency (%) 0 98 93 96 80 77 relative growth 2.14 1.94 1.50 1.53 1.45 1.14 cr uptake (mg/kg) 13.63 2,158.60 5,498.70 8,260.01 10,887.66 11,229.30 bcf 1,078.81 1,374.67 1,376.67 1,360.96 1,122.93 42 3.2 phytoremediation of cadmium by a. pinnata the highest cd removal efficiencies were observed in the 0.5 ppm and 1 ppm treatments, where 88% and 76% removal efficiencies were recorded in the respective treatments. the calculated bcfs of the 0.5 ppm and 1 ppm treatments were above 1,000. in contrast, at concentrations above 1 ppm, the calculated bcfs were well below 1,000. in all treatments, there was a significant reduction in growth with only scarce growth observed after 7 days in all treatments above 0.5 ppm cd. 3.3 phytoremediation of nickel the highest ni removal efficiency of 57.05% was observed in the 2 ppm treatment. all bcfs of a. pinnata exposed to ni treatments were well below 1,000. in all treatments, there was a strong growth retardation observed in a. pinnata plants, even though the ni removal efficiencies were below 57% for all concentrations (2 to 10 ppm) of ni tested (table 3). table 3: mean values of removal efficiency, relative growth, uptake and bio concentration factor of nickel by a. pinnata. parameter control 2 ppm 4 ppm 6 ppm 8 ppm 10 ppm removal efficiency (%) 0 57 50 42 40 25 relative growth 2.26 1.64 1.26 1.14 1.13 1.05 ni uptake (mg/kg) 0 1,095.84 2,739.79 3,173.48 3,567.91 4,366.93 bcf 547.92 684.95 528.91 445.99 436.69 3.4 phytoremediation of lead by a. pinnata the highest removal efficiency of pb (86%) was observed in the 8 ppm treatments. the highest pb accumulation of 10,660.22 mg/ kg of dry weights of plants was shown in a. pinnata plants exposed to 8 ppm treatment. bio concentration factors of a. pinnata exposed to pb treatments of 4, 6 and 8 ppm, exceeded 1000, where respective bcfs of 1,158.51, 1,113.29 and 1,332.53 were calculated (table 4). table 4: mean values of removal efficiency, relative growth, uptake and bio concentration factor (bcf) of lead by a. pinnata. parameter control 2 ppm 4 ppm 6 ppm 8 ppm 10 ppm removal efficiency (%) _ 79 81 85 86 76 relative growth 2.81 2.40 2.37 2.13 2.02 1.54 pb uptake (mg/kg) 6.29 1,875.31 4,634.03 6,679.72 10,660.22 9,824.71 bcf _ 937.65 1,158.51 1,113.29 1,332.53 982.47 mandakini et al. /journal of tropical forestry and environment vol. 6. no 01 (2016) 36-49 43 3.5 phytoremediation of each heavy metal ion in a collective pool of each other a treatment of all four heavy metal ions was formulated by collectively pooling each heavy metal ion at the concentration at which the highest bcf was reported in each of our individual experiments. the concentration of each heavy metal ion that was used for this collective treatment is as follows; cr–6 ppm, cd–0.5 ppm, ni–4 ppm and pb–8 ppm. table 5: relative growth, removal efficiency, metal uptake and bcfs of a. pinnata for cr, ni, cd and pb in a collective pool of each other. the initial concentrations of each metal in the collective treatment are provided in the table below. removal percentage (%) heavy metal initial con. final con. removal % cr 6 1.15 81 ni 4 1.78 56 cd 0.5 0.09 83 pb 8 1.20 85 relative growth 1.39 uptake capacity (mg/kg) cr 6142.64 ni 2719.87 cd 524.19 pb 7518.18 bcf cr 1023.77 ni 679.97 cd 1048.39 pb 939.77 our results demonstrate that in the collective pool of heavy metal ions, cr (6 ppm) and cd (0.5 ppm) were sequestered efficiently as reported by their high bcf factors. however, a. pinnata showed a significant decline in the phytoremediation potential of ni in the collective presence of the four heavy metal ions and is likely weakened by competitive ions and polluters which act to perturb the growth and physiology of the a. pinnata plant. furthermore, consistent with what was reported earlier in this study, a. pinnata was a poor candidate in the removal of ni from heavy-metal infested reservoirs. 3.6 phytoremediation of industrial effluents containing heavy metals since data are strongly favorable for the use of a. pinnata in the phytoremediation of cr, cd and pb, it was important to extend the ex-situ experiments to assess the sanitisation of industrial effluents by the a. pinnata water fern. the collected leachate were serially diluted to a form a series of dilutions (5%, 15%, 25%, 50%, 75%, 100%) and the dilutions were phytoremediated in triplicate using a. pinnata. our data demonstrate that up to a dilution strength of 15%, cr, cd and pb are 44 efficiently sanitized by a. pinnata, as indicated by the high bcf factors calculated for a. pinnata in the 5% and 15% leachates. table 6: bio concentration factor of a. pinnata for cr, cd, ni and pb in different leachate concentrations. metal ion 5% 15% 25% 50% 75% 100% cr 1248.51 1185.60 609.11 721.98 449.32 473.97 cd 1199.19 1040.90 882.02 442.50 341.64 328.62 ni 867.33 746.78 570.71 272.87 165.97 114.85 pb 1355.43 999.19 993.24 535.38 336.45 227.62 4. discussion a. pinnata possesses a remarkable capacity to hyperaccumulate heavy metals from polluted water bodies (wagnar, 1997). ex situ research carried out by salt et al., (1995), bennicelli et al., (2004), jangwattana., (2010), sood et al., (2011), deval et al., (2012), moradi et al., (2013), sufian et al., (2013), thayapara et al., (2013) have shown the uptake and retention capacities of a. pinnata species to different heavy metal ions. these findings suggest at the potential and the applicability of a. pinnata species to phytoremediate heavy metal polluted water reservoirs. the primary characteristics of macrophytes that possess strong phytoremediation capacities are their faster growth rates, higher biomass and greater adaptability to wide range of environmental conditions. the ability of the endosymbiont in a. pinnata (nostoc azollae) to assimilate atmospheric nitrogen and to enhance the overall growth of the plant is an important attribute that is utilised to engender profuse propagation of the water fern in irrigated environments. moreover, the free floating nature of a. pinnata and other macrophytes facilitates harvesting and their higher water content in fresh biomass (9094%), which drastically reduces in volume after drying, solves to a great degree the disposal dilemma of harvested material. the dry a. pinnata biomass can easily be transported to recycling sites for the recovery of the heavy metals (sood, 2011). furthermore, a. pinnata possesses a remarkable ability to survive in highly polluted waters with wide spectra of ph, temperature and salinity, reflecting its suitability for phytoremediation applications. 4.1 phytoremediation potential of a. pinnata in environmentally-relevant ranges of heavy metals there are many sources of heavy metal ions to the wider environment including waterways. cr is primarily generated through disposed batteries, anodizing and other metal finishing operations, tannery, paint and textile industries while pb is released from disposable batteries, paints, via fossil fuel combustion and through runoff from road sediments of pb which pollute urban waterways. cd though is largely produced by the agrochemical triple super phosphate (tsp) which contains between 23.5 to 71.7 cd/kg (noble et al., 2014) and such release of cd is thought to be the main contributory factor for the presence of the often fatal illness, ckdu, in the dry zone of sri lanka. there are environmental standards determined by international bodies and local regulatory organisations that ensure that heavy metals are kept below a threshold level of contamination of mandakini et al. /journal of tropical forestry and environment vol. 6. no 01 (2016) 36-49 45 public waterways/catchments as well as public water supply. for example, the maximum concentration of cd in drinking water as enforced by who stands at 0.003 ppm. however, it is of strong concern that in a study undertaken by bandara, (2003), cd levels of 0.03-0.06 ppm were reported in water samples from several reservoirs especially in north central province. therefore, although in this study we have strived to treat ex-situ reservoirs with environmentally-relevant level of the tested heavy metals, it should be noted that higher contamination levels are often encountered in pollution sites. our results demonstrate that environmentally-relevant cr and pb, are easily phytoremediated up to a concentration of 10 ppm of the treated heavy metal. the bcfs for cr at all treated concentrations were above a value of 1000 and for pb, only the bcf values at 2 ppm and 10 ppm were marginally lower to the threshold level (937 and 982 ppm respectively), suggesting that for both cr and pb, there is strong phytoremediation of the respective heavy metal ions from the treated water aquariums. in the case of cr, the removal percentages dropped with increased treatment concentrations which were analogous to the data reported on a. pinnata (bennicelliet et al., 2004). in the case of cd, there was sound phytoremediation at 0.5 and 1 ppm, where bcf values were over 1,000, but beyond this value cd sequestration was hindered in particular by toxicity effects of cd. cd, which is both a residue of agrochemicals and industrial effluents has been pointed as one of the primary candidates for the etiology of ckdu and the transmission of cd up the food chain is of grave danger to human health. therefore it appears that a. pinnata is an efficient tool for the removal of low levels of cd (below 1 ppm) from polluted water reservoirs. a separate study has also demonstrated that a. pinnata is a sound phytoremediation tool and a useful bio fertilizer up to a concentration of 1ppm cd, beyond which both growth and photosynthesis was handicapped due to oxidative damage induced by superoxide radicals and hydrogen peroxide (prasad and freitas, 2003). it is of significance that ni was not efficiently remediated by the a. pinnata as indicated by the low bio-concentration factors for all treatments tested. still, there was some removal of ni from waterways suggesting that even ni can by accumulated in tissues of a. pinnata. 4.2 phytoremediation by a. pinnata in collective enrichments of heavy metals past studies have reported that in the presence of an array of contaminants, there can be varying consequences on the individual uptake of a heavy metal ion, due to complex formation, reactivities, decreased bioavailability, competition and inhibitory effects. it is due to such phenomena that we tested the sequestration of individual heavy metal ions, in aquariums treated with all heavy metal ions used in this study. it has been reported that one of the most critical influences on individual heavy metal uptake is the supplementary metal concentrations in the medium (marbaniangand chaturvedi., 2014). for example, in a study by rofkar et al., (2014), it was demonstrated that the presence of silicon (si) and copper (cu), decreased the accumulation of arsenic (as) by azolla caroliniana. this experiment was designed to entertain collectively the concentrations with the highest bcfs for individual ions, as determined by the bcfs calculated for a. pinnata in a series of individual treatments for each heavy metal ion. the bcf values obtained from collective treatment 46 of cr, cd, pb and ni, demonstrated that high bcf values were retained for cr (6 ppm) and for cd (0.5 ppm) even in the presence of competing ions, suggesting that there was minimal displacement of uptake of cr and cd by the presence of auxiliary heavy metals. on the other hand, the phytoremediation of pb was marginally decreased in the presence of three other co-polluting heavy metal ions, suggesting that there may have been interactive or competitive effects that could have hindered the accumulation of lead by the a. pinnata. 4.3 applications of a. pinnata to industrial effluents/treated samples numerous studies have demonstrated that industrial effluents can be sanitised by using plants of high phytoremediation potential. for example, in a study by rizwana et al., (2014), the phytoremediation potential of eicchornia crassipes, lemna trisulca, oenathe javanica and lepronia articulate were identified, due to their efficient removal of cd and pb from textile industry effluents. however growth retardations, such as in vetivaria zizanioides, due to the presence of mn, fe and cu, as reported by roontanakiat et al., 2007, are a common characteristic due to the toxic nature of heavy metal ions. in this experiments with industrial effluents, it was observed that cr and cd was amenable for phytoremediation at 5% and 15% dilutions of leachate as indicated by bcfs over 1000 for both. pb too showed a high bcf values nearing or above 1000 for the 5% and 15% leachates demonstrating that at lower dilutions of effluents (such as following chemical or physical treatment), there is good potential for phytoremediation by a. pinnata. it is suggested that industrial leachates which are treated initially with chemicals or filtered through membranes/adsorption surfaces, and thus diluted, are sound contenders to be phytoremediated by macrophytes such as a. pinnata. therefore a shallow to medium-depth pondbased system where a. pinnata is cultivated as a surface lining can be used successfully to cleanse industrial effluents such as cr, cd and pb and such a system is worth an effort to exploit the potential of biological heavy metal quenchers such as a. pinnata to sanitize industrial residue, prior to their contamination of public waterways. 4.4 growth responses of a. pinnata to selective and collective heavy metals growth changes are often the first and most obvious indicators of plants under heavy metal stress (deval et al., 2012). in this study, plant growth was measured in terms of relative growth of the treated plants as compared to the corresponding negative control (in the absence of heavy metal treatment). in the presence of cr and pb (between a range of 2 and 10 ppm), the growth of a. pinnata was inhibited by 9-47% and 14%-45% respectively compared to the corresponding controls and there was a dose-dependency of the retardation of growth to the level of treatment of the selected heavy metal. the presence of ni (2 to 10 ppm) caused a direct reduction of a. pinnata growth by 27-54% relative to the negative control even though the removal efficiencies of ni were low at all concentrations tested. a growth reduction of 12-52% was observed in the presence of cd (0.5–3 ppm) relative to the negative control. a. pinnata exposed to 0.5 ppm treatment showed the highest relative growth of mandakini et al. /journal of tropical forestry and environment vol. 6. no 01 (2016) 36-49 47 1.95 and in all other treatments (1-3 ppm), there was no significant growth recorded, while the plants appeared to undergo chlorophyll degradation due to the decoloration of fronds. similar observations were made by lu et al., (2004) and hasan et al., (2006) where the relative growth of water hyacinth plants were significantly decreased with moderately high cd concentrations (2 and 4 ppm). uysal and taner (2009) also reported that high cd concentrations created various toxicity symptoms on lemna minor such as yellow coloration of plant leaves and decomposition of plants. in another study by delgado et al., (1993) concerning the phytotoxic effect stemming from the uptake of cd, cr and zn by water hyacinths, cd was identified as most toxic to the water hyacinth plants. therefore, our results agree with past findings on the formidable toxicity of cd to macrophytes and other water plants. 5. conclusion we conclude by nominating a. pinnata as a phytoremediation agent that can be used for the sanitization of selective heavy metals, namely cr, cd and pb and this technology offers efficient, easy, cost-effective, environmentally-sustainable solution to the problem of heavy metal accumulation in public reservoirs and waterways. it is of significance that in sri lanka, a fatal and debilitating condition designated as ckdu is fast reaching epidemic status and cd which has been shown to be relevant to the etiology of this illness, requires to be extracted from contaminating sites such as irrigated rice fields, waterways and reservoirs. a. pinnata, which is abundantly used as a nitrogen-infuser for rice cultivation provides a vehicle for purifying water bodies infested with cd, and thus allows for the arrest of transport of cd up the food chains and through water consumption and consequently will contribute towards the management of the disease and the diseased in relation to ckdu. it is also suggested that artificial pond-based systems cultivated with a. pinnata can easily be employed as a biological filter to quench heavy metal ions from industrial effluents and to let the resultant flow-through exit from the drainage system. using such a filter-system will ensure that industrial pollutants are trapped, removed and destroyed prior to their contamination of public water bodies. the easily harvestable nature of a. pinnata is of significant benefit both in industrial ponds and in rice fields where pollution from effluent discharge and agrochemical usage is of major concern. the use of mechanical or manual harvesting can easily be performed and the heavy-metal enriched water ferns can be used for the chemical extraction of heavy metals such as cr and pb, which have numerous applications once recycled. therefore, a. pinnata, although not a panacea for heavy metal contamination, offers a feasible solution to remediate polluted water bodies by the entrapment of selective heavy metals within the biological tissues of this miniature green wonder. references apha 1999. standard method for examination of water and waste water. american public health association, american water works association and water environment federation. bakar, a.f.a., yusoff, i., fatt, n.t., othman, f. and ashraf, m.a. 2013. arsenic, zinc, and aluminium removal from gold mine wastewater effluents and accumulation by submerged aquatic plants (cabomba piauhyensis, egeria densa, and hydrilla verticillata). biomed research international, http://dx.doi.org/10.1155/2013/890803. bandara, n.i.g.j., 2003. water and wastewater issues in sri lanka. water science & technology, 47: 305-312. http://dx.doi.org/10.1155/2013/890803 48 bediako, e.o., 2013. potentials of adiantum raddianum and nephrolepis exaltata for phytoextraction of heavy metals in spiked soils. m. sc. thesis, department of environmental science, kwame nkrumah university of science and technology, ghana. bennicelli, r., stezpniewska, z., banach, a., szajnocha, k. and ostrowski, j. 2004. the ability of azolla caroliniana to remove heavy metals (hg(ii), cr(iii), cr(vi)) from municipal waste water. chemosphere, 55: 141–146. delgado, m., bigeriego, m., guardiola, e. 1993. uptake of zn, cr and cd by water hyacinth, water research, elsevier, 27(2): 269–272. deval, c. g., mane, a. v., joshi, n. p. and saratale, g. d. 2012. phytoremediation potential of aquatic macrophyte azolla caroliniana with references to zinc plating effluent. emir. journal of food agriculture, 24(3): 208-223. hasan, s.h., talat, m. and rai, s. 2006. sorption of cadmium and zinc from aqueous solutions by water hyacinth (eichchorniacrassipes). bioresource technology, science direct, 98: 918– 928. jangwattana, r. 2010. using azolla pinnata for waste water treatment from poultry farm. international journal of environmental and rural development, 1(2). kalra, y.p. 1998. handbook of reference methods for plant analysis. soil and plant analysis council, crc press, taylor & francis group. lu, x., kruatrachue, m., pokethitiyook, p.and homyok, k. 2004. removal of cadmium and zinc by water hyacinth, eichhornia crassipes. science asia, 30: 93-103. marbaniang, d., and chaturvedi, s.s. 2014. assessment on cr, cd, as, ni and pb uptake and phytoremediation potential of scirpus mucronatus, international journal of scientific research & management, 2(6): 965-969. moradi, s., yosefi, r. and ghaderi, o. 2013. bioconcentration factor and relative growth rate of azolla (azolla caroliniana) in arsenic and salinity stress conditions. international journal of agronomy & plant production, 4 (10). noble, a.; amerasinghe, p.; manthrithilake, h.; arasalingam, s. 2014. review of literature on chronic kidney disease of unknown etiology (ckdu) in sri lanka. colombo, sri lanka: international water management institute (iwmi), 41p. (iwmi working paper 158), doi: 10.5337/2014.206. prasad, m.n.v. and freitas, h.m. 2003. metal hyperaccumulation in plants-biodiversity prospecting for phytoremediation technology. electronic journal of biotechnology, 6(3). rizwana, m., darshan, m. and nilesh, d. 2014. phytoremediation of textile waste water using potential wetland plant: eco sustainable approach. international journal of interdisciplinary & multidisciplinary studies, 1(4): 130-138. rofkar, j.r., dwyer, d.f. and bobak, d.m. 2014. uptake and toxicity of arsenic, copper, and silicon in azolla caroliniana and lemna minor. international journal of phytoremediation, 16(2): 155-166, doi: 10.1080/15226514.2012.759534. roongtanakiat, n., tangruangkiat, s. and meesat, r. 2007. utilization of vetiver grass (vetiveria zizanioides) for removal of heavy metals from industrial wastewaters. science asia, 33: 397403. salt, d.e., blaylock, m., kumar, n.p.b.a., dushenkove, v., ensley, b.d., chet, i., raskin, i., 1995. phytoremediation: a novel strategy for the removal of toxic metals from the environment using plants. biotechnology, 13. mandakini et al. /journal of tropical forestry and environment vol. 6. no 01 (2016) 36-49 49 sood, a., uniyal, p.l., prasanna, r. and ahluwalia, a.s. 2011. phytoremediation potential of aquatic macrophyte, azolla, royal swedish academy of sciences, springer, 41: 122-137. [online] doi 10.1007/s13280-011-0159-z. sufian, j., golchin, a., avanes, a. and moradi, s. 2013. potentials of azolla (azollam caroliniana) for uptake of arsenic from contaminated waters with different levels of salinity. international journal of agriculture and crop sciences, 6(12): 778-783. thayapara, m., iqbal, s.s., chathuranga, p.k.d. and iqbal, m.c.m. 2013. rhizofiltration of pb by azolla pinnata. international journal of environmental sciences, 3(6), doi:10.6088/ijes.2013030600002. uysal, y. and taner, f. 2009. effect of ph, temperature, and lead concentration on the bioremoval of lead from water using lemna minor, international journal of phytoremediation, 11(7): 591-608, doi: 10.1080/15226510902717648. wagnar, g.m. 1997. azolla: a review on its biology and utilization. botanical reviews, 63: 1–26. xiaomei, l., maleeya, k., prayad, p. and kunaporn, h. 2004. removal of cadmium and zinc by water hyacinth, eichhornia crassipes. scienceasia, 30: 93-10. islam and chowdhury. /journal of tropical forestry and environment vol. 7, no. 02 (2017) 85-96 85 equation for estimating stem volume for agar tree(aquilaria malaccensis lamk) grown in the plantationsin bangladesh s.m.z. islam1, 2* and m.a.m. chowdhury2 1, 2 forest inventory division, bangladesh forest research institute, chittagong, bangladesh 2jamal nazrul islam research centre for mathematical and physical sciences, university of chittagong, chittagong-4331, bangladesh date received:04-10-2017 date accepted: 01-12-2017 abstract agar tree (aquilaria malaccensis lamk, familythymeleaceae) has drawn unique position due to the production of world’s most expensive essential oil used in fragrances and also medicine. it is one of the most valuable and economically important commercial tree speciesplanted in some potential forest areas of bangladesh. the main aim of this study is to develop mathematical models for total volume estimation of agar tree. in order to meet the requirements we have selected 21 models of volume equation which are tested by regression technique. among them for one way volume equation 2cdbdav  and for two way volume equation hddchbdav 2 appeared to the best model for estimating the agar tree volume.from these models conversion factors equationfr = d/(a+bd+cd 2)(r =11, 13, 15) has been determined to estimate under bark volume and under bark volume of different top end diameters of 11, 13, and 15 centimeters. keywords:aquilaria malaccensis, model,stem volume andvalidation 1. introduction volume equations play an important role in forest management. the importance ofvolume equations are indicated by the existence of numerous such equations andthe constant search for their improvement.among various characteristics volume estimation is the most important features to know. for more than a century, researchers make an effort to estimate the volume of different trees over the time. now a days reasonably a number of volume equations have been used to estimate tree and stand volume, and have played a significant role in forest inventories and management.sustainable forest management requires among othersknowledge on the total volume of the growing forest stock.usually volume is estimated as total volume per unit area,whereby models predicting total tree volume of individualtrees are used. studies of tree volume began in the early nineteenth century. a numerous equations has been published in forest literature (spurr 1952, clutter et al. 1983, avery & burkhart 2002, abel 2014,latif & islam 2014). because of inherent morphological differences among tree species, it is generally necessary to develop separate standard volume equations for each species or closely related species group (burkhart & gregoire 1994). these are simple methods and tools that can be used to obtain individual tree volume and the volumes of entire stands. such information is vital for forest management. the objective of any volume equations to provide accurate estimates with acceptable levels of local bias over the entirediameter range in the data.equations that provide accurate predictions of volumewithout local bias over the entire range of diameter are one of the basic building blocks of a forest growth and yield simulation system (bi & hamilton 1998). *correspondence: zahir.fid.bfri@gmail.com tel: 088 01837000010 issn 2235-9370 print / issn 2235-9362 online ©university of sri jayewardenepura 86 development of sound management practice is oneof the major priorities oftheforestry sector. tree volume equation provide to the tree biomass and carbon estimation in non-destructive way.even though volume equations have been studied for many years, but still the research is continuing even more vitally. one reason is that there is no single theory in volume equations that can be used satisfactorily for all tree species (clutter et al. 1983; muhairwe 1999). another reason is that volume equations are required to be increasingly accurate and flexible in their predictions. forest measurement needs to be improved because market requirements for timber have become more specific in recent years. volume equations have been developed more than forty different important tree species in bangladesh (latif and islam 2014; islamet al. 2014). a considerable amount of work on volume has been done by researchers of bangladesh forest research institute (bfri). however, there have been no studies on volume equation for agar tree(aquilaria malaccensis lamk) plantations in bangladesh. agar treeis an evergreen tropical tree species found in the aquilaria species of the thymelaeaceae family. the most highly valuable non-timber forest products itisharvested from tropical forests and used in the manufacture of perfume, incense, traditional medicine, and other commercial products by muslims and asian buddhists (turjaman et al.,2006). the aromatic resin known as locally ‘agar’ yield an essential oil that is a key perfume ingredient through distillation, meanwhile, incense are commonly processed from distillation residues and lesser quality material. agar tree(a. malaccensis lamk) is a major producer of agar wood in bangladesh for international trade. natural populations of agar treeare distributed in south and southeast asia and in bangladesh it occurs mostly in the forests of sylhet, chittagong and chittagong hill tracts (rahman and basak 1980). this tree is also found in nepal, bhutan, north eastern india (assam, arunachal pradesh, nagaland, meghalaya, mizoram, manipur, and tripura), myanmar, thailand, laos, indonesia, malaysia, vietnam, cambodia, south-eastern china, brunai darus-salam, the philippines, islands of east indias and papua new guinea (baksha et al. 2009, burkhill 1966). agar tree (a. malaccensis lamk)is known to be one of the most important species of commerce and valued for production of its impregnated resinous heart wood that gives fragrance. bangladesh has favorable climate for agar tree plantation(baksha et al. 2009). the bangladesh forest department has taken an initiative to expand and popularize agar plantation in the country from 1998-2005 considering the economic value of such a unique forest resource, particularly for its demand in the international market (bfd).about 800 ha of land have been planted under this project. among these plantations 324 ha are in sylhet, 282 in chittagong, 189 in cox’s bazar and 5 ha in and chittagong hill tracts (baksha et al. 2009).following this it has been extensively used as a plantation species different ngos (brac) and private planters.the aim of the present study is to develop volume equations foragar tree(aquilaria malaccensis lamk) plantations in the potential forest areas of bangladesh. 2. material and methods 2.1 study area the bangladesh forest department has taken an initiative to expand and popularize agar plantation in the country considering the economic value of such a unique forest resource, particularly for its demand in the international market. they cultivate agar tree under agar plantation project in many potential places in sylhet, chittagong, cox's bazar and in the districts of chittagong hill islam and chowdhury. /journal of tropical forestry and environment vol. 7, no. 02 (2017) 85-96 87 tracts. the study has been conducted in the remnant the existence agar tree plantationin several forest beat of these forest areas. 2.2 measurement of trees data were collected from available plantation in sylhet, chittagong, cox's bazar and the districts of chittagong hill tracts. 250 standing agar trees in representing different diameter classes were selected at random for preparation of mathematical volume equation and tables. trees diameter at breast height (dbh) in cm and total height in meter were measured with diameter tape and hagaaltimeter respectively. the collected data were categorized on the basis of dbhand height of the trees. the dbh-height class distribution of the sample trees are given in table 1. the diameter and bark thickness at one meter intervals up to 7.5 cm top end diameterin the stem were measured by climbing the trees with a ladder. the mid diameter of big branches also measure for branch volume. the bark thicknesses of the samples were measured with a bark gauge.summary statistics of the collected representative trees are shown in table 2. table 1:dbhand total height class distribution of the sampled trees selected for volume estimation of agar tree(aquilaria malaccensis lamk) plantation in bangladesh. dbhclasses (cm) total height class total number of trees <5 (5-8) (8-11) (11-14) [14-17) ≥ 17 [8-11) 4 9 13 [11-14) 12 18 2 32 [14-17) 5 30 15 50 [17-20) 1 20 36 3 60 [20-23) 4 30 15 1 50 [23-26) 6 19 7 32 ≥ 26 9 4 13 4 27 72 89 46 12 250 table 2:summary statistics of dbh and height of sample trees. variables n mean min max s.e sd dbh (cm) 250 18.4 8.6 38.5 0.3 5.4 height (m) 250 11.5 4.0 19.5 0.2 3.3 2.3 compilation of data volumes of all sections except top and bottom section were determined by using the crosssectional areas of the two ends of each section following smalian’s formula, 𝐶𝑢𝑏𝑖𝑐 𝑣𝑜𝑙𝑢𝑚𝑒 = [(𝐵 + 𝑏)/2]𝐿 (1) where: b= the cross-sectional area at the large end of the log b= the cross-sectional area at the small end of the log l= log length 88 in determining the volume of bottom sections (frustum), the volume of a conoidoid of basal diameter d, top diameter d and height h is calculated as: 𝑉 = 𝜋𝐻 12 × (𝐷2 + 𝐷 × 𝑑 + 𝑑2). assuming the top section as cone the volume was computed to one third of the cylindrical volume of the portion. we considered the top end diameter measurement for each tree as the base diameter of the cone. the branch log volume calculated by cylindrical volume formula. in computing the under bark volume of the tree the volume of top section i.e. cone was ignored. the volume of the tree is the sum of the volume of total sections and big branches found in a tree. the individual tree volumes (v), dbh (d) and total height (h) were variable in regression techniques using various functions and transformations as required in the models. 2.4 computation of volume function multiple regression analysis techniques were used to select the best suited model equations. the following 21 models (clutter et al. 1983; bi and hamilton 1998)were tested to select the equation of best fit with different variables as follows. bdav  (2) 2 cdbdav  (3) 2 bdav  (4) 2 bdadv  (5) 1  bdadv (6) 2  bdadv (7) bdav )log( (8) )log( dbav  (9) )log()log( dbav  (10) hbdav 2  (11) chbdav  (12) hcdbdav 2  (13) cdhbdav  (14) ddhchbdav  (15) hddchbdav 2  (16) ddhchbdav  2 (17) hddchbdav 22  (18) hddcdhbdav 22  (19) )log()log( hcdbav  (20) )log()log()log( hcdbav  (21) 11   chbdav (22) islam and chowdhury. /journal of tropical forestry and environment vol. 7, no. 02 (2017) 85-96 89 where: v= total volume over bark in cubic meters d= diameter at breast height in centimeters h= total height in meters a = regression constant b, c, d= regression coefficients the logarithmic functions are to the base e following original and transformed variables were used to select the best suited regression models. dependent variables: v, log (v) independent variables: d, d,d-1, d-2, h, h-1, dh, d 2 h, log (d), log(h) the dependent variables mentioned above were regressed with the independent variables. the equations of the best fit based on the highest multiple coefficients of determination (r2); f-ratio, lowest residual mean square (rmse), aic value and durbin-watson statistic were chosen. models for estimation of the total volume over bark were selected and to estimate under bark volume and under bark volume to top end diameters of approximately 11, 13and 15 cm were also estimated. 2.5 model validation statistical validation the best suited models were tested with a set of data recollected from 30 trees of different diameter class and complied in the same procedure as earlier. the actual volumes of these trees were collectively compared with the corresponding volume predicted by the selected models. the independent tests for validation were the absolute paired t-test, chi-square test,deviation percentand 45 degree line test (islam et al. 1992). 2.6 data analysis data collected were organized and screened (removing the outliers) for analysis. descriptive statistical analysis was further carried out in order to summarize the data. all analysis carried out were conducted using ms excel 2013, spss 17 inc and eviews (quantitative micro software, llc) statistical package version 9. 3. results and discussions 3.1 dependent and independent variables for efficient and accurate tree volume modeling, field data must be statistically and biologically valid before using them to develop models. in this study the data used were carefully obtained from the field and subjected to biological validation and the results indicated a normal distribution pattern as lower diameter to highest diameter. the collected data shows that number of the trees are increased lower diameter to mid-diameter simultaneously decreases from mid-diameter to highest diameter (figure 1). hence the number samples normally distributed with independent variable. 90 (a) (b) figure 1:distribution of sample trees by (a) diameter and (b) height classes for estimating total volume of agar tree (aquilaria malaccensis lamk). total volume over bark has been calculated from total of 250 individual trees in this study. the scatter plot of the individual actual total volume and dbh& height for individual trees of agar treeplantations in bangladesh is presented by figure 2. it is also scatter relationship between dependent variable (volume) and independent variables (dbh and height) using the actual field data before model fitting. from the figure it is shows that tree volume increased rapidly as dbh increased; however, as the dbh increased further, the increase in tree volume slowed down and the volumedbhcurve became less steep (figure 2a). it is also shows that tree volume increased slowly as height increased upto 15m, then it was increased rapidly(figure 2b). present study performed to develop one way and two way volume equation of agar tree by using these variables. (a) (b) figure 2:the scatter plot of the individual actual total volume with independent variable (a) diameter and (b) height of agar tree(aquilaria malaccensis lamk). 13 32 50 60 50 32 13 0 10 20 30 40 50 60 70 n u m b e r o f tr e e s diameter classes (cm) 4 27 72 89 46 12 0 20 40 60 80 100 <5 [5-8) [8-11) [11-14) [14-17) >=17 height classes (m) 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.0 10.0 20.0 30.0 40.0 50.0 t o ta l v o lu m e ( m 3 ) diameter at breast height(cm) 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0 5 10 15 20 25 total height (m) islam and chowdhury. /journal of tropical forestry and environment vol. 7, no. 02 (2017) 85-96 91 3.2 estimated parameters estimated parameters of fitted models are presented in table 3. the 21 models were tested to develop equation for total volume of agar tree. the first 9 models are one way volume models and the 12 remaining models at the bottom are two way volume models. nine models had two, seven models had three and five models had four estimated parameters. the standard errors given in the table show that all the partial regression coefficients were significant except for model 6. table 3:values of coefficients for different models obtained for fitting data set. model no estimated parameter standard error of parameter a b c d a b c d 1 -0.2386 0.0226 0.0076 0.0004 2 -0.1226 0.0105 0.0003 0.0182 1.80e-03 4.24e-05 3 -0.0188 0.0005 0.0039 9.10e-06 4 -0.0014 0.0006 0.0004 1.75e-05 5 0.0159 -1.9163 0.0003 0.0812 6 0.0135 -17.5016 0.0002 1.0054 7 -4.3638 0.1291 0.0601 0.0032 8 -0.9864 0.4058 0.0319 0.0111 9 -9.2309 2.5244 0.1146 0.0398 10 0.0340 2.97e-05 0.0030 4.77e-07 11 -0.2464 0.0211 0.0032 0.0079 0.0007 0.0011 12 -0.0900 0.0100 1.72e-05 0.0139 0.0011 1.44e-06 13 -0.1553 0.0122 0.0005 0.0118 0.0013 5.63e-05 14 -0.0139 0.0051 -0.0134 0.0011 0.0202 0.0014 0.0016 9.16e-05 15 -0.0975 0.0094 0.0018 1.68e-05 0.0143 0.0011 0.0009 1.45e-06 16 0.0016 0.0002 -0.0074 0.0009 0.0148 4.41e-05 0.0026 0.0001 17 -0.0542 0.0003 0.0065 8.10e-06 0.0114 4.57e-05 0.0010 2.83e-06 18 -0.0386 0.0003 0.0005 1.82e-07 0.0080 4.19e-05 5.83e-05 3.17e-06 19 -0.9885 0.4141 -0.0091 0.0322 0.0202 0.0184 20 -9.0504 1.8123 0.7766 0.0773 0.0486 0.0443 21 0.5458 -6.7319 0.3140 0.0157 0.4592 0.2269 table 4 compares the fit statistics for each of the equations except model 6 used. the r2 values were generally high and acceptable for all the equations except model 7, 8, 19 and 21 (considered only r2 ≥ 0.9) while rmse values were very low except for model 9 and 20. in this table also shows that aic values are low which are ranked as closed to zero. the positive serial correlation attains in all models as durbin-watson statistic measuresbelongs to (0, 2). final ranking showed that model 2 ranked first for one way volume prediction followed by model 9, 1, 3, 4 and 5. similarly, model 15 ranked first for two way volume prediction followed by model 20, 13, 10, 12, 17, 11, 14, 16 and 18. 92 table 4:fit statistics for volume equations of agar tree(aquilaria malaccensis lamk). models no df r2 rmse aic dw ∑rank final rank one way 1 248 0.93 (3) 0.03 (1) -3.9 (4) 1.6 8 3 2 247 0.95 (1) 0.03 (1) -3.1 (2) 1.6 4 1 3 248 0.93 (3) 0.03 (1) -3.9 (4) 1.5 8 3 4 248 0.93 (3) 0.03 (1) -3.9 (4) 1.5 8 3 5 248 0.90 (4) 0.04 (2) -3.5 (3) 1.4 9 4 7 248 0.87 0.27 0.2 1.1 8 248 0.84 0.05 -3.1 1.4 9 248 0.94 (2) 0.18 (3) -0.5 (1) 1.3 6 2 two way 10 248 0.94 (4) 0.03 (1) -4.1 (3) 1.3 8 3 11 247 0.93 (5) 0.03 (1) -4.1 (3) 1.5 9 4 12 247 0.96 (2) 0.03 (1) -4.3 (6) 1.5 9 4 13 247 0.95 (3) 0.03 (1) -4.2 (4) 1.4 8 3 14 246 0.96 (2) 0.03 (1) -4.4 (7) 1.4 10 5 15 246 0.97 (1) 0.03 (1) -3.4 (2) 1.5 4 1 16 246 0.96 (2) 0.03 (1) -4.4 (7) 1.4 10 5 17 246 0.95 (3) 0.03 (1) -4.3 (5) 1.5 9 4 18 246 0.96 (2) 0.03 (1) -4.4 (7) 1.5 10 5 19 247 0.84 0.05 -3.1 1.4 20 247 0.94 (4) 0.12 (2) -1.3 (1) 1.6 7 2 21 247 0.71 0.07 -2. 5 1.3 values in the parentheses give the ranks. model 2 and 15 performed the best fit model of one way and two way volume equations respectively. figure 3 (a and b) illustrates the predicted volumes ofall trees in data set by the best fitted equation against the observed (actual) volumes. the figure shows that the volumes had a curvilinear relationship with diameter at breast height(d). (a) (b) figure 3:the scatter plot of the observed volume and predicted volume against d by selected model (a) one way and (b) two way of agar tree(aquilaria malaccensis lamk). 0 0.2 0.4 0.6 0.8 1 0.0 20.0 40.0 60.0 t o ta l v o lu m e ( m 3 ) diameter at breast height(cm) observed volume predicted volume 0 0.2 0.4 0.6 0.8 1 0.0 20.0 40.0 60.0 diameter at breast height(cm) observed volume predicted volume islam and chowdhury. /journal of tropical forestry and environment vol. 7, no. 02 (2017) 85-96 93 3.3 volume equations the regression models number 2 and 15 are best suited for one way and two way volume equations. the volume equations have been selected for estimation of the stem volume over bark (v) and conversion factors to estimate under bark stem volume and under bark volume to different top end diameters of 11, 13, and 15 centimeters form these models. the coefficients of determination for selected volume equations are 0.95 and 0.97 for one way and two way volume equations respectively. this means that the selected models describe over 95 (one way) and 97 (two way) percent of the total variations. the best fitted models were selected for estimation of volume on dbhand total height. the selected volume equations and conversion factor equations are given in table 5. table 5:selected tree volume equation for different proportion of agar tree(aquilaria malaccensis lamk) planted in bangladesh. volume equations r-squared observation 𝑉𝑜𝑏 = −0.122589 + 0.010486 × d + 0.000292 × 𝐷 2 0.95 250 𝑉𝑜𝑏 = −0.097547 + 0.009443 × d + 0.001784 × h + 0.000017 × 𝐷2 × h 0.97 250 𝐹𝑢𝑏 = 0.801610 + 0.009261 × d − 0.000120 × 𝐷 2 0.96 250 𝐹11 = 𝐷/(16.213335 − 0.004324 × d + 0.017740 × 𝐷 2) 0.90 250 𝐹13 = 𝐷/(28.151346 − 0.553977 × d + 0.023831 × 𝐷 2) 0.88 246 𝐹15 = 𝐷/(62.345233 − 2.852730 × d + 0.062848 × 𝐷 2) 0.91 241 where: d = diameter at breast height in centimeter h = total height in meters vob= total volume over-bark in cubic meters fub= conversion factor for under-bark volume f11 , f13 and f15 = conversion factors for the volume to 11 cm, 13 cm and 15 cm top end diameter respectively. 3.4 model validation statistical validation the statistical requirement to best fitted models by considering those equations having the highest r2 with lowestrmse, akaike information criterion (aic) and the durbin–watson statistic (dw) were tested. results were presented in table (4). independent test the best suited volume equations for one way and two ways were tested with a set of data recollected from 30 trees of different diameter class and complied in the same procedure as earlier. the actual volumes of these trees were collectively compared with the corresponding volume predicted by the selected models. the independent tests for validation were the chi-square test, paired t-test, absolute deviation percent (%ad) and 45 degree line test (islam et al. 1992). the computed chi-square, t-values, absolute deviation percent and slope for total height of aquilaria malaccensis lamk (agar tree) are given table (6). 94 table 6:result of independent test. models chi t %ad slopeo one way 0.127 0.34 0.17 44.4 two way 0.128 0.49 0.12 43.7 chi-square test the computed chi-square values of total volume over bark represent in table 4 were less than the tabular valuesx20.95,29 = 17.71. this implies that there is no significant difference between the actual values from the 30 test sample trees and the corresponding expected values as predicted by the selected models. paired t-test the result of pared t-test for total volume over bark of a. malaccensis lamk (agar tree) planted in bangladesh are given in table 4computed t-ratio for all the estimation were less than the tabular values 045.229,95.0 t . these imply that there were also no significant differences between the observed and predicted values. thus the prediction models might be accepted. percent absolute deviation (%ad) test absolute deviation percent (%ad) between the observed and predicted values for total volume over bark with diameter at breast height and dbh & height for this study species was minimum, which also confirmed validity of the selected models. 45degree line test graphs comparing the observed values and the predicted values were plotted in the graph paper. the observed values and the predicted values yielded slops very closed to 45 degrees, whic h have been presented in table 5. it was observed that the models tend to make an angle 45 degrees with the axes, meaning there were no significant difference between the actual and the predicted values. figure 4 shows that the predicted total volume over bark plotted against actual total volume over bark with 45-degree line test for best sited equation for tree volume estimation of aquilaria malaccensis lamk (agar tree) planted in bangladesh. islam and chowdhury. /journal of tropical forestry and environment vol. 7, no. 02 (2017) 85-96 95 (a) (b) figure 4: observed vs. predicted tree volume over bark for the validation data set with 45-degree line test by selected models for (a) one way (b) two way volume of aquilaria malaccensis lamk (agar tree) planted in bangladesh. confidence limits these volume equations should not be used to estimate volumes of individual trees in a stand. these tables may be used for the mean tree of a stand which may be multiplied by the number of stems to get the total volume of the stand. estimation of the volumes for the trees outside the height and dbh ranges shown in the stand table should only be done with caution. most of the models except models 19 and 21 were equally good fitted models with statistical and biological validation. the model 2 and model 15 are performed well in both the fitting and validation process for one way volume and two way volume respectively. model 15 was the most precise and least biased model of them. it was ranked first by three statistics including r2, rmse and aic (table 4) which better than selected single-entry model. it is clear that the model of the form using dbh, ht (height) and dbh2×ht as the predictor variables provided good estimates of volume for agar tree planted in bangladesh. in model 20 the natural logarithmic form using dbh and height as the predictor variables provided also good estimates of volume. it was ranked second by three same statistics(table 4). 4. conclusions it can be concluded from the study that the combined variable two equations (model 2 and 15) performed well in both the fitting and validation process. therefore, it can be used to predict volume for agar tree(a. malaccensis lamk) in the study area. the contrasting results obtained between model fitting and validation emphasis the need for model validation as an important step in the model construction process in order to get the best choices. acknowledgements the authors are thankful to the ministry of environment and forestry of bangladesh, for providing the study leave for this study. we are gratefully acknowledged to the bangladesh agriculture research council provided support for phd project from which this research has come. we also grateful to all respective forest officers and stuffs of bangladesh forest department who providing support during data collection of this study. y = 0.9805x 0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.00 0.20 0.40 0.60 0.80 p re d ic te d v o lu m e ( m 3 ) actual volume (m3) y = 0.9562x 0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.00 0.20 0.40 0.60 0.80 actual volume (m3) 96 references abel, m. m., eliakimu, z., rogers, e. m., ole, m. b., tron, h. e., 2014. volume models for single trees in tropical rainforests in tanzania. journal of energy and natural resources. vol. 3, no. 5, 2014, pp. 66-76. doi: 10.11648/j.jenr.20140305.12 avery, t.e., burkhart, h.e. 2002. forest measurements. boston: mcgraw-hill. 456 pp. baksha, m. w., akhter, s., basak, a. c., rahman, m. s., 2009. bangladeshy agar chas o agar kutirsilpo (agar cultivation and cottage industry in bangladesh). bangladesh forest research institute, chittagong 20pp (a booklet in bangla) huiquan, bi,hamilton, f., 1998. stem volume equations for native tree species in southern new south wales and victoria. australian forestry 61(4): 275-286. burkhart, h. e., gregoire, t. g. 1994. handbook of statistics, vol. 12, chap. forest biometrics, pp377-407. new york: elsevier science publisher. (vol. 12). new york: elsevier science publisher. burkill, i. 1966. a dictionary of economic products of the malay peninsula. vol. i. government of malaysia and singapore. the ministry of agricultural and cooperatives, kuala lumpur. 198206 pp. clutter, j.l.,fortson, j.c.,pienaar, l.v.,brister, g.h.,bailey, r.l., 1983. timber management: a quantitative approach. john wiley & sons, usa. 333 pp. islam, s. m. z., khan, m.i., ahmed, k.u., 2014. mathematical volume equation and table of rubber tree, (hevea brasiliensis. muell arg.), bulletin no. 10. forest inventory division. bangladesh forest research institute, p. o. box-273, chittagong 4000, bangladesh. 24 pp islam, s.s, waziullah, a.k.m., reza, n.a., 1992. validation of the existing volume tables of telyagarjan (dipterocarpus turbinatus) in bangladesh. bangladesh j. for. sci. 21(182):60-66 latif, m.a., islam, s. m. z., 2014. growth, yield, volume and biomass equation and tables for important trees in bangladesh. forest inventory division. bangladesh forest research institute, p. o. box-273, chittagong 4000, bangladesh. 106 pp muhairwe, c.k., 1999. taper equations for eucalyptus pilularis and eucalyptus grandis for the north coast in new south wales, australia. forest ecology and management 113: 251-269. rahman, m.a., basak, a.c., 1980. agar production in agar trees by artificial inoculation and wounding. bano bigan patrika 9 (1&2): 86 93. spurr, s.h., 1952. forest inventory. ronald press, new york. 476pp. turjaman, m.,santoso, e.,sumarna, y., 2006. arbuscural mycorrhizal fungi increased early growth of gaharu wood of aquilaria malaccensis and a. crasna under greenhouse conditions. j. for. res., 2: 139-148. issn 2235-9370 print / issn 2235-9362 online ©university of sri jayewardenepura table 6:result of independent test. madurapperuma & dellysse /journal of tropical forestry and environment vol. 8, no. 01 (2018) 25-35 25 coastal fringe habitat monitoring using kite aerial photography: a remote sensing-based case study b.d. madurapperuma1, 2* and j.e. dellysse2 1department of forestry and wildland resources, humboldt state university, usa 2department of environmental science and management, humboldt state university, usa date received: 2017-11-26 date accepted: 2018-06-15 abstract monitoring coastal ecosystem resilience for climatic and/or anthropogenic vulnerabilities is challenging with moderately resolution landsat images. a simple, low-cost kite aerial photograph platform (kap) was vital to obtain high-resolution images for a small area to develop coastal gis models. this study examines post-tsunami relief in two coastal shrub ecosystem and a mangrove ecosystem in terms of vegetation bioshield mass and sea level rise perspectives. a kap platform was created using two light-weight automatic cameras with dual bandpass red-nir filters, a picavet stabilizing rig, a gps tracker and a parafoil kite. the kap images were processed to build mosaic images, orthorectified and geo-referenced digital elevation model (dem) using structure-from-motion (sfm) and remote sensing software (agisoft photoscan and envi respectively). kap has been utilised for coastal mapping under three scenarios: (i) object-orient feature extraction for discriminate prosopis juliflora, an invasive alien species, and texture analysis for coastal shrub and herbaceous vegetation classification (ii) dem for sea level rise, and (iii) normalized difference vegetation index (ndvi) for mangrove bioshield mass estimation. the image processing produced a point cloud with an average density of 35 points/m2; a dem with 17 cm resolution; and an orthophoto mosaic with an average resolution of 4.0 cm. the results showed that object orient feature extraction can discriminate prosopis juliflora from the coastal shrubs with 62% accuracy, while supervised classification accuracy was 51%. mangrove vegetation in rekawa was discriminated from grassland and other coastal shrub vegetation types at ≥4 ndvi threshold resulted in 0.33 ha of mangroves (28% of 1.15 ha of the total area). the kahandamodara beach coastal vegetation was dominant by ipomoea pes-capre with 26% coverage. in conclusion, kap has a wide potential to bridge science with high spatial/temporal resolution in-situ data for coastal habitat mapping, where the researchers can utilize the data within a low-cost budget. keywords: kite mapping, coast, dem, mangrove, ndvi 1. introduction coastal habitats are dynamic ecosystems that are critically important to conserve and provide better ecological services. in sri lanka, diverse coastal habitats are vulnerable to natural and/or anthropogenic disturbances such as tsunami, climate change, land-use/cover change and invasion of alien species etc. for example, coastal highlands in sri lanka transform to different land-uses often due to human settlements (chen and ye, 2014), agriculture (dellysse and madurapperuma, 2017), fish hatcheries (cattermoul and devendra, 2002), and tourist industries (savundranayagam et al., 1994). *correspondence: bdm280@humboldt.ed issn 2235-9370 print/issn 2235-9362 online © university of sri jayewardenepura daham doi: 10.31357/jtfe.v8i1.3480 this leads to change coastal geomorphology as well as coastal biomass loss causing environmental vulnerabilities such as flooding, cyclones and sea level rise. therefore, monitoring historical land-use change along the coastline is important to make sustainable land-use planning in future to mitigate climatic and/or anthropogenic disturbances. a wide-scale mapping conducts using medium resolution images, such as landsat images (dellysse and madurapperuma, 2017; dellysse et al., 2017) due to limited availability of high-resolution images. for example, a coastal gis model was developed to measure the changes to coastal vegetation and assess the resilience of several coastal biomes of sri lanka pre and post 2004 tsunami based on landuse categories; paddy, garden, coconut, dense forest, open forest, water bodies and other types of landuses (dellysse and madurapperuma, 2017). furthermore, dellysse et al. (2017), reported that humaninduced land uses such as paddy and garden were more vulnerable than natural vegetation for tsunami disaster in hambantota district. these land-use categories were used to extrapolate changes and as indicators of health and resilience for several coastal biological services or biomes; mangrove forests, salt marshes, home gardens and coastal scrubs (bambaradeniya et al., 2005). these biological services offer protection from previous and current coastal land disturbances i.e. increased wave action from sea level rise (slr) and large, infrequent actions i.e., tsunamis. furthermore, these biomes and root structures offer coastal stabilization of terrestrial soil structures and prevent coastal ecosystem degradation while acting as a biosheild. almost half of sri lanka's southern coastline was affected by the devastating effects of seawater inundation and related debris contamination post-tsunami (illangasekare, 2006). much of the coastal and inland ecosystems were severely affected by salt water and a host of other contaminants (dellysse et al., 2017). when analyzing the effects on these ecosystems by wave action, inland flooding from slr and tsunamis the inevitable consequences and vulnerability of these low lying coastal communities and habitats becomes apparent. kite aerial photography (kap) is very reliable for coastal mapping in sri lanka due to low-cost, high resolution, limited regulation and easy flying during high wind velocity. kap has been used for different coastal applications such as coral reefs mapping (currier, 2015), sediment depositional characteristics (bryson et al., 2016), coastal erosion (madurapperuma et al., 2017a) and sea level rise (madurapperuma et al., 2017a). this study examines post-tsunami relief and recovery of coastal shrub and mangrove vegetation in hambantota utilizing kap for vegetation bioshield mass characteristics and sea level rise scenarios. there are three main objectives of this study. one is to compare prosopis juliflora (an invasive alien species) extent in coastal habitat using feature extraction and supervised classification methods. the second is classify coastal vegetation using high-resolution kite aerial images and estimate the mangrove vegetation extent using ndvi threshold. the third objective is to create dem and elevation profiles in coastal habitat to determine the sea level rise vulnerabilities. 2. methodology 2.1 study area the preliminary study on coastal land-use change pinpointing tsunami in hambantota using landsat images (dellysse and madurapperuma, 2017) were subjected to a fine scale assessment using high-resolution kite aerial photographs to understand long-term recovery from boxing day tsunami. we sampled three tsunami study sites in hambantota (adopted from bambaradeniya et al., 2006; site 20: beach near sea spray hotel in hambantota, site 12: kahandamodara beach, and site 10: rekawa turtle sanctuary) by acquiring kite aerial photographs to observe vegetation recovery at two coastal shrub and a mangrove vegetation (figure 1). 26 madurapperuma & dellysse /journal of tropical forestry and environment vol. 8, no. 01 (2018) 25-35 27 figure 1: google earth image showing the three study sites of hambantota district: two coastal shrub vegetation (kahandamodara and hambantota beach areas) and a mangrove vegetation (rekawa). 2.2 equipment and methods a kap platform was created using two light-weight automatic cameras with dual bandpass rednir filters, picavet stabilizing rig (bryson et al., 2012), gps tracker and a parafoil kite (figure 2). the kite was flown 10-15 minutes under 15-20 mph wind speed. aerial images collected using two downwards-facing canon power shot a490 digital camera (one color and one near-infrared) at 15 m altitude. a perpendicular transects from shoreline to interior coastal vegetation were made to cover an average extent of one ha. ground control points were collected from land-use features, such as rock, fishing boats, fence posts and trees using a garmin gps receiver with 5 m accuracy (madurapperuma et al., 2017a). figure 2: kap platform build-up with two cameras (left), attached picavet stabilizing rig to a string (middle) and parafoil kite in the air (right). 2.3 image processing and analysis the high-resolution kap images were processed to build mosaic images, orthorectified and georeferenced dems using structure-from-motion (sfm) and remote sensing software (agisoft photoscan and envi respectively). high-resolution orthomosaic imagery has been utilized for coastal mapping under three scenarios: (i) vegetation classification using object-oriented feature extraction, supervised classification and unsupervised classification (madurapperuma et al., 2018) (ii) digital elevation model for sea level rise (madurapperuma al., 2017a) (iii) normalized difference vegetation index (ndvi) for vegetation bioshield mass estimation (madurapperuma al., 2017b). vegetation classification the coastal shrub vegetation in hambantota beach area was co-dominant by two invasive alien species viz., prosopis juliflora in the overstory and opuntia dillenii in the understory. the study estimated the p. juliflora extent using two methods, such as object-oriented feature extraction and supervised classification (madurapperuma al., 2018). a 150 random points were generated from the vegetated area to perform the accuracy assessment for p. juliflora occurrence habitats to evaluate the accuracy of two classification methods. another coastal habitat in kahandamodara beach area was mapped using texture analysis and unsupervised classification. texture analysis is a method of calculating varying texture differences in each pixel by comparing its neighboring pixels (srinivasan and shobha, 2008). in order to perform texture analysis, mean and standard deviation of band 3 (red band) and band 1 (blue band) that sensitive to vegetation signature was performed using focal statistics function in arcgis©. the composite image was created combing the mean and standard deviation images and natural color image. the composite image (eight bands together) was classified into five classes using an unsupervised classification and then the classes further collapsed into three land-use classes, namely coastal shrub, coastal herbaceous and open space. sea level rise (slr) the dem that created from the kap images and ground control points was used to create slr model. a google earth image was used to create elevation profile from shoreline to upland vegetation that is useful to get the inundation levels when creating slr. for example, the elevation for the study area 28 madurapperuma & dellysse /journal of tropical forestry and environment vol. 8, no. 01 (2018) 25-35 29 ranged from 3 to 9 m and therefore the slr was created for 3, 5, 7 and 9 m inundation levels (a detailed slr adopted to this study is available at: http://gsp.humboldt.edu/olm_2016/activities/gsp_270/09_sealevelrise_rasters/lab9_rasteranalysisi. html). normalized difference vegetation index (ndvi) the ndvi was calculated using red and nir bands of the kap image using band math function of envi® using the following equation. ndvi = (nir red) / (ir + red) (1) the mangrove vegetation was extracted using ndvi threshold ≥ 4 as suggested by vo et al. (2013). 3. results the kap is useful for multi-scale assessment of coastal habitat vulnerabilities that produces detail information, for example, coastal biomass health to pinpoint tsunami mitigation measures. the results present here for two coastal shrub vegetation and a mangrove vegetation in hambantota showing the results of vegetation classification, sea level rise model and ndvi for assessing of vegetation biosheild health. figure 3: vegetation bioshield at hambantota coastal area (6.132588 n; 81.130718e). the overstory vegetation dominant by prosopis juliflora and understory vegetation dominant by opuntia dillenii (a). the kap images of coastal vegetation at 15 m altitude: (i) rgb color (b) and (ii) nir color (c). vegetation bioshield at hambantota coastal area is studied using high-resolution kite aerial photographs. a coastal shrub vegetation of hambantota beach was mainly dominant by prosopis juliflora in the overstory and opuntia dillinii in the understory (figure 3). two classification techniques were used to compare the prosopis juliflora acreage in the coastal shrub vegetation. feature extraction techniques estimated 1.32 ha of p. juliflora, while supervised classification estimated 3.11 ha. the accuracy assessment for the two methods revealed that comparatively high accuracy for feature extraction technique (figure 4). kap images at kahandamodara beach area were used to classify coastal shrub and herbaceous vegetation using texture analysis and unsupervised classification. the extent of the area is one ha. the unsupervised classification identified three classes, such as coastal shrub, coastal herbaceous and open space (figure 5). the major vegetation type is coastal shrub dominant by pandanus odoratissimus, scaevola takkada and calotropis gigantea (bambaradeniya et al., 2006). the leading herbaceous species is ipomoea pes-capre. the total coverage of coastal shrub and coastal herbaceous was 55% and 26% respectively. figure 4: estimation of prosopis juliflora extent in coastal shrub vegetation in hambantota (6.132548 n; 81.130816 e) using feature extraction (a) and supervised classification (b) techniques. a locator map and high-resolution kite aerial photograph are shown in fig 1c. 30 madurapperuma & dellysse /journal of tropical forestry and environment vol. 8, no. 01 (2018) 25-35 31 figure 5: vegetation bioshield at kahandamodara beach area (6.063593 n; 80.89767 e). a google earth image of kahandamodara beach area (a), color image (b) and texture analysis and unsupervised classified image (c). the elevation profile from coastline to inland vegetation was created using the google earth imagery and the elevation was ranged from 3 m to 9 m (figure 6). this elevation range was used to create sea level rise model at 2 m intervals, i.e. 3 m, 5 m, 7 m and 9 m. the slr results show that 3 m elevation inundates coastline, while 9 m elevation floods some coastal vegetation (figure 7). figure 6: elevation profile of the study area from the sea level 3m to the upland 9 m. figure 7: sea level rise model created from dem at hambantota coastal shrub vegetation. figure 8: vegetation bioshield at rekawa mangrove area (6.056456 n; 80.854696 e). a google earth image of rekawa mangrove area and its surrounding (a). a nir image (b) and the ndvi image (c) mangrove vegetation. we assessed vegetation health at rekawa mangrove restoration area in hambantota using ndvi that was derived from nir images (figure 8). the vegetation cover in the area is 1.15 ha with 4 cm spatial resolution and the point cloud density is 56 points/m2. mangrove acreages within the study area 32 madurapperuma & dellysse /journal of tropical forestry and environment vol. 8, no. 01 (2018) 25-35 33 were estimated using ndvi threshold of 0.4 that adopted by vo et al. (2013) and the ndvi ranged for this study was 0.4 to 0.95. according to the results, 0.33 ha (28% of total area) was mangroves and 0.46 ha (40%) was grassland and other coastal shrub vegetation. 4. discussion in the coming decades, the coastal biomes will be primary indicators of ecological, agricultural and sociological health as climate change intensifies the natural forces along the world's coastlines in the coming decades (liquete et al., 2013). the predicted slr up to 1.3 m by 2100 will adversely affect for a small island like sri lanka causing flooding, seawater inundation at agricultural lands and coastline erosion (grinsted et al., 2010). for example, madurapperuma et al. (2017a) slr model at oluvil beach showed that the proposed oluvil harbor will significantly flood at 1.5 m level due to severe coastal erosion (ameer, 2015). coastal gis and remote sensing models are useful to recognize spatial patterns of biophysical features of the coast and bioshield mass resilience from slr and tsunami. various sensors and algorithms have been utilized in remote sensing for mapping biomass in coastal habitats. landsat images with moderate resolutions of (~30 m) have been used for regional coastal vegetation mapping at community levels (i.e., xie, 2008; o’donnell and schalles, 2016; dellysse and madurapperuma, 2017; dellysse et al., 2017). ndvi as a graphical indicator is a widely used algorithm for estimating biomass with in-situ empirical biomass data that plugs into mathematical equations (o’donnell and schalles, 2016). however, the landsat data is limiting when mapping particular species distribution. kap was acquired at three study sites of bambaradeniya et al. (2006) and therefore one-to-one habitat characteristics of two sites were compared to evaluate the rehabilitation of coastal vegetation. according to bambaradeniya et al. (2006) survey, hambantota beach site was poorly regenerated with ipomoea pescaprae but in this study showed prosopis juliflora and opuntia dillenii were occupied the habitat. as previous research suggested p. juliflora and o. dillinii established very well in degraded coastal ecosystems due to high survival rate in the poor saline soil, high regeneration and the nature of invasive behavior (dilhan, 2005, chandrasekara et al., 2001, seneviratne et al., 2001). kahandamodara beach (bambaradeniya et al. 2006) had high beach replenishment with >60% plant regeneration with ipomoea pes-caprae, calotropis gigantea and scaevola taccada. the dominant coastal shrub species recorded in this study area was pandanus odoratissimus (figure 5), which has high resistance potential for waves. the species composition changes after tsunami disaster have to be considered for best coastal management implications. the kite flew in the coast at low altitude and obtained kap at 4 cm spatial resolution, which was useful to make vegetation classification and sea level rise model using high-resolution dem. similarly, kap has taken for mapping of intertidal landscapes at sub-centimeter resolution (bryson et al., 2013), intertidal vegetation monitoring at 4 cm resolution (pauly and clerck, 2011) and ecological surveys of coral reef at 15 cm resolution (currier, 2015). kap has been utilized for several coastal applications to address the knowledge gaps. for example, this study was able to extract p. juliflora from kap derived orthoimagery using feature extraction technique, which is useful to forest managers to apply management priority for controlling the species based on its invasiveness. furthermore, the ndvi derived from this study can adopt to estimate biomass of p. juliflora as procedures described by gunawardena et al. (2014). furthermore, coupling ndvi with texture analysis was able to estimate mangrove extent in rekawa, which is useful to monitor deforestation on mangrove vegetation and implementing best coastal conservation plans to mitigate human-induced pressures on coastal vegetation. despite kap advantages (low-cost, high spatial resolution, limited regulation) there are a few limitations, such as gps not being available in low cost, lightweight cameras onboard as in unmanned aerial vehicle that can geotag each image and therefore many ground control points need geo-referencing kap. this affected the creation of a dem and some software (precision mapper) could not recognize kap images due to an unbranded camera. some mosaic images have holes and blur features cause errors when image analysis was applied. in addition, some human footprints and gcp markers deteriorate the image quality. although with such limitations, we depicted multi-scale utility of kap through our groundbreaking research. furthermore, this preliminary study will be utilized to a larger scale study using uav imageries to pinpoint gis model and coastal recommendations to protect the sri lanka coastline from slr and future tsunami damage. 5. conclusions monitoring finer changes of vegetation and capturing micro-topographical features of coastal habitats are challenging with 30 m resolution landsat images. however, high-resolution aerial imageries are the limited resource available freely for public and therefore we utilized kap for vegetation bioshield mass assessment using automated image analysis methods. this study estimated p. juliflora extent in coastal habitat using feature extraction and supervised classification methods, which is useful to forest managers to find out critical areas for conservation priorities. the mangrove vegetation delineation using kap derived ndvi is precise due to high spatial resolution (~4 cm) compared to landsat images that have moderate spatial resolution (~30 m). creating very high-resolution dem using kap is essential to see how coastal habitats are vulnerable to sea level rise. overall, kap has a great potential to bridge science with high spatial/temporal resolution in-situ data for coastal habitat monitoring, where our researchers can utilize the data within a low-cost budget. references ameer, f., 2015. physical impacts of oluvil harbour. 5th international symposium 2015 – intsym 2015, seusl, pp 450-461. bambaradeniya, c., perera, s.,samarawickrema, p., 2006. a rapid assessment of post-tsunami environmental dynamics in relation to coastal zone rehabilitation and development activities in the hambantota district of southern sri lanka. iucn occasional paper no. 10. bryson, m., duce, s., harris, d., webster, j.m., thompson, a., vila-concejo, a., williams, s.b., 2016. geomorphic changes of a coral shingle cay measured using kite aerial photography. geomorphology, 270, 1-8. bryson, m., johnson-roberson, m., murphy, r. j., bongiorno, d., 2013. kite aerial photography for lowcost, ultra-high spatial resolution multi-spectral mapping of intertidal landscapes. plos one, 8(9), e73550. bryson, m., johnson-roberson, m., murphy, r., 2012. low-cost, ultra-high spatial and temporal resolution mapping of intertidal rock platforms. international archives of the photogrammetry, remote sensing and spatial information sciences, volume xxxix-b8, 2012xxii isprs congress, 25 august – 01 september 2012, melbourne, australia, 243-248. cattermoul, n., devendra, a., 2002. a measurement of the ecological footprint of shrimp farming in the chilaw lagoon area, fieldwork report 2.3a, university of portsmouth cemare, 1-33. chandrasekara, c.m.c.p., perera, g.a.d., senevirathne, g., 2001. effect of soil nutrient status on the invasion of prosopis juliflora and opuntia dillenii at bundala national park. proceedings of the 57th annual sessions of the sri lanka association for the advancement of science. chen, m., ye, c., 2014. differences in pattern and driving forces between urban and rural settlements in the coastal region of ningbo, china. sustainability, 6(4), 1848-1867. currier k., 2015. mapping with strings attached: kite aerial photography of durai island, anambas islands, indonesia, journal of maps, 11:4, 589-597, doi: 10.1080/17445647.2014.925839. dellysse, j.e., madurapperuma, b.d., 2017. tsunami effects and mitigation results for south-east regions in sri lanka, ideafest conference, 21st april 2017, 2nd floor library, humboldt state university. dellysse, j.e., madurapperuma, b.d., kuruppuarachchi, k.a.j.m. 2017. preliminary study on biomass mapping along the coastal zone of hambantota region, sri lanka using landsat imagery, the open university research sessions, 16th and 17th november 2017, 497-500. 34 madurapperuma & dellysse /journal of tropical forestry and environment vol. 8, no. 01 (2018) 25-35 35 dilhan, m.a.a., 2005. vegetation structure and floristic composition in the irrigation extension area of the lower walawe basin, sri lanka. m.phil. thesis, postgraduate institute of science, university of peradeniya. grinsted, a., moore, j.c., jevrejeva, s., 2010. reconstructing sea level from paleo and projected temperatures 200 to 2100 ad. climate dynamics, doi: 10.1007/s00382-008-0507-2. gunawardena, a.r., fernando, t.t., nissanka, s.p., dayawansa, n.d.k., 2015. assessment of spatial distribution and estimation of biomass of prosopis juliflora (sw.) dc. in puttlam to mannar region of sri lanka using remote sensing and gis. tropical agricultural research. 25(2), 228– 239. doi: http://doi.org/10.4038/tar.v25i2.8144 illangasekare, t., tyler, s.w., clement, t.p., villholth, k.g., perera, a.p.g.r.l., obeysekera, j., gunatilaka, a., panabokke, c.r., hyndman, d.w., cunningham, k.j., kaluarachchi, j.j., 2006. impacts of the 2004 tsunami on groundwater resources in sri lanka. water resources research, 42(5): w05201. liquete, c., piroddi, c., drakou, e.g., gurney, l., katsanevakis, s., charef, a., egoh, b., 2013. current status and future prospects for the assessment of marine and coastal ecosystem services: a systematic review. plos one, 8(7), e67737. madurapperuma, b., close, p., fleming, s., collin, m., thuresson, k., lamping, j., dellysse, j., cortenbach, j., 2018. habitat mapping of ma-le'l dunes coupling with uav and naip image. in proceedings of the 2nd international electronic conference on remote sensing, 22 march–5 april 2018; sciforum electronic conference series, vol. 2, 2017, doi:10.3390/ecrs-2-05182 madurapperuma, b.d., dellysse, j.e., zahir, i.l.m., iyoob, a.l., 2017a. mapping shoreline vulnerabilities using kite aerial photographs at oluvil harbour in ampara, 7th international symposium 2017 (intsym2017)-seusl 07th & 08th december 2017, 197-204. madurapperuma, b.d., dellysse, j.e., kuruppuarachchi, k.a.j.m., dissanayake, g.k.p., 2017b. mapping topographic and vegetation bioshield mass recovery along the shoreline using kite aerial photography. proceedings of the 22nd international forestry and environment symposium 2017 of the department of forestry and environmental science, university of sri jayewardenepura, sri lanka. p.78. o’donnell, j.p., schalles, j.f., 2016. examination of abiotic drivers and their influence on spartina alterniflora biomass over a twenty-eight year period using landsat 5 tm satellite imagery of the central georgia coast. remote sensing, 8(6), 477. doi:10.3390/rs8060477 pauly, k., clerck, o., 2011. low-cost very high resolution intertidal vegetation monitoring enabled by near-infrared kite aerial photography. www.vliz.be/imisdocs/publications/225813.pdf savundranayagam, t., de alwis, l., joseph, l., siripala, n., 1994. the economic significance of the coastal region of sri lanka, working paper no. 06, coastal conservation department and the coastal resources management project, sri lanka. seneviratne, g.i., algama, a.l.m.n.s., 2001. invasive species prosopis juliflora in the coastal region of hambantota district. sri lankan biodiversity review 1, 79-83. srinivasan, g.n., shobha, g., 2008. statistical texture analysis. in proceedings of world academy of science, engineering and technology, vol. 36, 1264-1269. vo, q.t., oppelt, n., leinenkugel, p., kuenzer, c., 2013. remote sensing in mapping mangrove ecosystems—an object-based approach. remote sensing, 5(1), 183-201. xie, y., sha, z., yu, m., 2008. remote sensing imagery in vegetation mapping: a review. journal of plant ecology, 1(1), 9-23.