Bangladesh J. Plant Taxon. 31(2): 279-292, 2024 (December) DOI: https://doi.org/10.3329/bjpt.v31i2.78754 © 2024 Bangladesh Association of Plant Taxonomists PLANT DIVERSITY, CONSERVATION WORTHINESS AND PEOPLE’S PERCEPTION IN FUTURE MANAGEMENT OF PURBACHAL SAL FOREST, BANGLADESH MD. TARIKUL ISLAM, ABULAIS SHOMRAT AND MOHAMMAD ZASHIM UDDIN* Department of Botany, University of Dhaka, Dhaka-1000, Bangladesh. Keywords: Plant diversity; Conservation; Sal Forest. Abstract The Purbachal Sal Forest, a vital ecosystem in the outskirts of Dhaka city facing biodiversity decline, was assessed for its plant composition and public perception of its management and conservation. A total of 190 species under 61 families have been recorded from the study area following the random quadrat method. Analyses showed that among the 190 species, the most abundant tree and shrub in the forest are Shorea robusta Roxb. ex Gaertn. and Melastoma malabathricum L., respectively. In case of dominance based on the Importance Value Index, Shorea robusta is the most dominant tree, followed by Melastoma malabathricum as the most dominant shrub. The percentages of native and exotic species were found to be 75% and 25%, respectively. The Shannon-Wiener Diversity Index in the study area was 0.61, whereas Simpson’s and Margalef’s Indices were 0.178 and 4.77, respectively. From interviews with visitors and stakeholders, this study revealed that the majority of them responded negatively about the presence of exotic species in the forest, and on the other hand, they responded positively on the question of incorporating experts in the management plan of the forest. A number of threats to the species diversity of the forest were recorded through observation in the field and stakeholders’ interviews, such as invasive alien species (IAS) intrusion, habitat destruction, agricultural practice, and deforestation. A set of recommendations, including planting more wildlife-supporting native species, preventing the spread of IAS like Parthenium L. and incorporating experts in the forest’s management, was developed for present and future management of Purbachal Sal Forest. Introduction Plant diversity serves as one of the basic eco-services all over the world, and urban vegetation provides an extensive range of ecosystem services, especially to the urban dwellers (Weber, 2013). The expansion of urban areas in Bangladesh has led to the decline of natural ecosystems, including Shorea robusta forests. The degradation of these forest ecosystems and biodiversity is caused by anthropogenic activity, including the alteration, reduction, and fragmentation of habitats (Popradit et al., 2015; Tittensor et al., 2014). Shorea robusta Roxb. ex Gaertn.is a semi-evergreen, tall tree that is naturally distributed on the Pleistocene tracts (Madhupur tracts) in Bangladesh (Rahman and Vacik, 2010; Singh and Kushwaha, 2005). This species is a keystone species that supports various endangered species (Hasnat and Hoque, 2016). The Purbachal Sal Forest is thought to be a part of the Madhupur tracts that encompasses different plant species, with Shorea robusta being the dominant one. The management and conservation of this forest are crucial for preserving plant diversity and ensuring the well-being of the local communities. However, the depletion of forests has been accelerated by the anthropogenic activities for implementing the ‘Purbachal New Town Project’ of RAJUK for the extension of Dhaka city and also by the introduction of some Invasive *Corresponding author: zashim01@gmail.com https://doi.org/10.3329/bjpt.v31i2.78754 280 ISLAM et al. Alien Species (IAS). There is the possibility of decreasing plant diversity, richness, and forest area for the acquisition of land. Therefore, a detailed study is needed to know the present condition of plant diversity and dominance and possible threats to this forest for future management. Moreover, this study aimed to gather stakeholders' perceptions regarding the future management practices of this forest. Materials and Methods Study area The Purbachal Sal Forest, situated in Rupganj Upazila of Narayanganj District and Kaligonj Upazila of Gazipur district, encompasses a vast area of 144 acres located at Sector-24 and Sector- 25 in Purbachal. Precisely located between 23.860616° North and 90.497203° East, now this forest is under the management of the Forest Department, which operates under the Ministry of Environment, Forests, and Climate Change of the Government of the People's Republic of Bangladesh. The annual mean air temperature of Purbachal is 28°C, and the annual precipitation is 2400 mm (Shapla et al., 2015). The hilly areas of Purbachal include scattered homesteads (i.e., settlement and residential areas) and homestead vegetation (including trees, shrubs, and herbs on and around the settlement). At the bottom of the valleys and depressions, one crop is cultivated annually (Shapla et al., 2015). Although the crop lands are being developed, Purbachal is a sanctuary of natural ecosystems supporting ecologically important species and habitats (Mamun, 2007). Fig. 1. Map showing locations of quadrats that were studied inside Purbachal Sal Forest. PLANT DIVERSITY, CONSERVATION WORTHINESS AND PEOPLE’S PERCEPTION 281 Floristic survey The floristic survey covered all the habitats and ecosystems of the study area and it was done covering all the seasons from August 2023 to August 2024 (Fig. 1). Random quadrat method (Subrahmanyam and Sambamurty, 2006) was applied for the survey and a total of 273 quadrats were surveyed in the study area. Sample size was determined using species area curve (Goldsmith and Harrsion, 1976). The quadrat size was taken as 10 m × 10 m for trees, 5 m × 5 m for shrubs and 2 m × 2 m for herbs according to Oosting (1956). In each sampling spots of 10 m × 10 m, names of the tree species present, their number of individuals and Circumference at Breast Height (CBH) (D’Eon et al., 1994) were recorded. Individuals having ≥ 30 cm CBH at breast height (1.3 m) were considered trees (Swaine and Alexander, 1987). For shrubs, species name with the individual numbers were recorded and for herbs, only the species were identified and recorded in their respective quadrats. Using a smartphone, GPS coordinates of the quadrat data were also noted in the same data sheet. Identification of species Identification of plant species was mostly done consulting experts and standard floristic literatures such as Ahmed et al. (2009a, b, c, d, e), Ahmed et al. (2008a, b), Prain (1903) and Hooker (1872-1897). High resolution smartphone camera (Samsung Galaxy S10 Plus) was used to capture close colored photos of plants to aid with identification. Moreover, for unidentified species, herbarium samples were prepared (Hyland, 1972). Some exotic plant species were identified comparing with the reports of Akter and Zuberi (2009) and Hossain and Pasha (2004). Besides, to identify unknown species, taken photographs and prepared herbarium samples were compared with herbarium specimens of Dhaka University Salar Khan Herbarium (DUSH) and Bangladesh National Herbarium (BNH). The family of each species was identified following the classification system of Cronquist (1981). Determination of phyto-sociological attributes and IVI Phyto-sociological attributes (density, frequency, abundance, their respective relative parameters and IVI = Importance Value Index) of the recorded tree and shrub species were determined for the whole site following the formulae of Shukla and Chandal (1994), Dallmeier (1992) and Verma and Agarwal (1986). To determine dominant tree and shrub species in the study site, Importance Value Index (IVI) was calculated using the following biostatistical formula (Krebs, 1989). Species diversity Species diversity was estimated using Shannon-Wiener diversity index (Shannon, 1948), Simpson‘s diversity index (Simpson, 1949) and Margalef’s index (Margalef, 1957) using the following formulae respectively. 𝑆ℎ𝑎𝑛𝑛𝑜𝑛 − 𝑊𝑖𝑒𝑛𝑒𝑟 𝐷𝑖𝑣𝑒𝑟𝑠𝑖𝑡𝑦 𝐼𝑛𝑑𝑒𝑥 = − ∑ 𝑝𝑖𝑙𝑛 𝑝𝑖 Here, pi = Proportion of observations found in category i. ln = Natural logarithm 𝑆𝑖𝑚𝑝𝑠𝑜𝑛′𝑠 𝐷𝑖𝑣𝑒𝑟𝑠𝑖𝑡𝑦 𝐼𝑛𝑑𝑒𝑥 = 1 − ∑ 𝑛 (𝑛 − 1) 𝑁 (𝑁 − 1) Here, N = Total number of individuals of all species n = Total number of individuals of a particular species 282 ISLAM et al. 𝑀𝑎𝑟𝑔𝑎𝑙𝑒𝑓 𝐼𝑛𝑑𝑒𝑥 = 𝑆 − 1 ln 𝑁 Here, S = Total number of recorded species N = Total number of individuals of all recorded species Interviews with stakeholders To gather the viewpoints of stakeholders on future management of Purbachal Sal Forest, interviews were conducted employing a structured close-ended questionnaire, following the methodology outlined by Alexiades (1996). This approach ensured that each participant was presented with the same set of questions in a consistent manner. Each question was also followed by a discussion on this study’s findings on plant diversity, so that the stakeholders could make educated comments. Results and Discussion Species composition A total of 190 species belonging to 61 families have been recorded. Among these species, 42 were tree species, 32 shrub species, 88 herb species and 28 climber species (Table 1). The survey indicated that not all families have equal representations in the study area. Among the 61 families, the largest 5 families contain 42% of the species and the remaining 56 families contain the rest 58% of the total species recorded. Poacea and Fabaceae are the largest family containing 12% each of all the species followed by Euphorbiaceae (8%), Asteraceae (5%) and Cyperaceae (5%). On average about 33 individuals of tree species has been found in each quadrat having a size of 100 sq. m. This shows a relatively high density of tree population in the study area. This is because that the forest has been left undisturbed for several years and it has observed a good amount of regeneration success, especially of Sal trees. Although Malakar et al. (2010) recorded a higher number of tree species (102 species) in the Madhupur Sal Forest compared to our study in Purbachal Sal Forest, this could be attributed to the Madhupur Sal Forest's greater age and larger size. Over centuries, the Madhupur Sal Forest has had more time and space for various species to establish themselves. In contrast, the Purbachal Sal Forest, according to the local people, was once a very dense forest with tall Sal trees. However, that forest underwent enormous logging and land grabbing, and now, it only stands as a small forest with small to medium sized Sal trees. Moreover, its shorter history may also explain the lower richness of tree species compared to the Madhupur Sal Forest. Based on the usefulness of plants, species found in the study area were categorized into a number of classifications such as medicinal, timber producing, ornamental, edible fruit-bearing, wildlife supporting, fooder and vegetable (Table 1). In some cases, the species are found to have multiple uses. Majority of the plant species recorded from Purbachal Sal Forest have medicinal uses (46%) followed by wildlife supporting (13%), timber producing (10%), fodder (10%), edible fruit bearing (9%), ornamental (7%) and vegetable (5%). The high percentage of medicinal species stems from the high number of herb species in the total species composition. On the other hand, though wildlife supporting species were recorded in good quantity from the area, these species were not abundant. The limited abundance of wildlife- supporting plant species restricts the forest's ability to support a significant population size of the wildlife. Considering the IVI, the forest has different fruit bearing species like Zizuphus mauritiana, Trema orientale and Bridelia tomentosa, these species have very few individuals which are PLANT DIVERSITY, CONSERVATION WORTHINESS AND PEOPLE’S PERCEPTION 283 random but scanty in the whole forest. These species, along with the dominance of Tectona grandis were observed in Nawabganj Sal Forest, Dinajpur by Jubair et al. (2023). Moreover, Malakar et al. (2010) recorded a total of 24 fruit bearing species from Madhupur Sal Forest whereas this present study recorded 17 species of edible fruit bearing trees. Though the number of edible fruit bearing and wildlife supporting species are quite close, the concern lies elsewhere. In case of Purbachal Sal Forest, these species are only found near the periphery of the forest, and in some open spaces inside the forest that have been cleared out of Sal trees by local people. Table 1. Species composition of the study area (Origin: E = Exotic, I = Indigenous; Use: M = Medicinal, T = Timber producing, O = Ornamental, F = Edible fruit bearing, Fd = Fooder, W = Wildlife supporting, V= Vegetable). Name of the species Habit Origin Family Local name Use Albizia chinensis (Osb.) Merr. Tree E Mimosaceae Chakua Koroi T Albizia julibrissin Durazz Tree E Mimosaceae Goalpi Sirish T Albizia lebbeck (L.) Benth. & Hook. Tree I Mimosaceae Kalo Koroi T Albizia procera (Roxb.) Benth. Tree I Mimosaceae Sada Koroi T Alstonia scholaris (L.) R. Br. Tree I Apocynaceae Chhatim T Aphanamixis polystachya (Wall.) R.N. Parker Tree I Meliaceae Royna (Boddira) M Azadirachta indica A. Juss. Tree E Meliaceae Neem M Barringtonia acutangula (L.) Gaertn. Tree I Lecythidaceae Hijol T Borassus flabellifer L. Tree I Arecaceae Tal F Bridelia retusa (L.) A. Juss. Tree I Euphorbiaceae Kamkui W Bridelia tomentosa Blume Tree I Euphorbiaceae Khoi W Butea monosperma (Lamk.) Taub. Tree I Fabaceae Polash O Careya arborea Roxb. Tree I Lecythidaceae Gola Kumbhi W Cassia fistula L. Tree I Caesalpiniaceae Sonalu O Catunaregam spinosa (Thunb.) Triveng. Tree I Rubiaceae Monkanta M Dillenia indica L. Tree I Dilleniaceae Chalta F Ficus benghalensis L. Tree I Moraceae Bot W Ficus hispida L.f. Tree I Moraceae Khoksha W Ficus racemosa L. Tree I Moraceae Jaga Sumur W Ficus religiosa L. Tree I Moraceae Asswath W Lagerstroemia speciosa (L.) Pers. Tree I Lythraceae Jarul T,O Lannea coromandelica (Houtt.) Merr. Tree I Anacardiaceae Jiga T,M Lepisanthes rubiginosa (Roxb.) Leenh. Tree I Sapindaceae Ban Lichu W Macaranga peltata (Roxb.) Muell.-Arg. Tree I Euphorbiaceae Pelta Bura W Mallotus polycarpus (Benth.) Kulju & Welzen Tree I Euphorbiaceae Shindur T Mangifera indica L. Tree I Anacardiaceae Aam F Melia azedarach L. Tree I Meliaceae Ghora Neem M Moringa oleifera Lamk. Tree I Moringaceae Sajna M,V Oroxylum indicum (L.) Kurz. Tree I Bignoniaceae Kanaidingi T Phoenix sylvestris Roxb. Tree I Arecaceae Khejur F Phyllanthus emblica L. Tree I Euphorbiaceae Amloki F Shorea robusta Roxb. ex Gaertn. Tree I Dipterocarpaceae Sal T Streblus asper Lour. Tree I Moraceae Sheora M Suregada multiflora (A. Juss.) Baill. Tree I Euphorbiaceae Ban-naranga F Syzygium fruticosum DC. Tree I Myrtaceae Buti Jam W Tamarindus indica L. Tree E Caesalpiniaceae Tentul F Terminalia bellirica (Gaertn.) Roxb. Tree I Combretaceae Bohera M Terminalia chebula Retz. Tree I Combretaceae Haritaki M Trema orientalis (L.) Blume Tree I Ulmaceae Jiban W 284 ISLAM et al. Name of the species Habit Origin Family Local name Use Zanthoxylum rhetsa (Roxb.) DC. Tree I Rutaceae Bajna T Ziziphus mauritiana Lamk. Tree I Rhamnaceae Boroi F Acacia pennata (L.) Willd. Shrub I Mimosaceae Bon Sirish T Dendrophthoe falcata (L. f.) Ettingsh Semi- parasite I Loganiaceae Dhaerordal F Abroma augusta (L.) L. f. Shrub I Sterculiaceae Ulotkambol M Ardisia humilis Thw. Shrub I Myrsinaceae Chaul Dhoa O Bridelia stipularis (L.) Blume Shrub I Euphorbiaceae Pat Khoi W Cajanus cajan (L.) Millsp. Shrub I Fabaceae Arhor V Calamus guruba Buch.-Ham. ex Martius Shrub I Arecaceae Bet W Calotropis gigantea (L.) R. Br. Shrub I Asclepiadaceae Akanda M Clerodendrum viscosum Vent. Shrub I Verbenaceae Bhat M Croton caudatus Geiseler Shrub I Euphorbiaceae Gograil M Flacourtia indica (Burm. f.) Merr. Shrub I Flacourtiaceae Boichi W Glochidion multiloculare (Roxb. ex Willd.) Muell.- Arg. Shrub I Euphorbiaceae Keora W Glycosmis pentaphylla (Retz.) A. DC. Shrub I Rutaceae Dantmajon W Hibiscus sabdariffa L. Shrub E Malvaceae Chukhair M Jatropha gossypiifolia L. Shrub E Euphorbiaceae Lalbherenda O Lippia alba (Mill.) Briton et Wilson Shrub E Verbenaceae Pichas Lakri M Melastoma malabathricum L. Shrub I Melastomataceae Datranga M Morinda angustifolia Roxb. Shrub E Rubiaceae Rang Gach M Phyllanthus reticulatus Poir. Shrub I Euphorbiaceae Chitki M Phyllodium pulchellum (L.) Desv. Shrub I Fabaceae Jata Salpani M Schoepfia fragrans Wall. Shrub I Olacaceae Guchchho gram M Senna alata (L.) Roxb. Shrub E Caesalpiniaceae Damardan M Senna occidentalis (L.) Link Shrub E Caesalpiniaceae Bara Kalkesunda M Senna tora (L.) Roxb. Shrub E Caesalpiniaceae Chakunda M Sesbania bispinosa (Jacq.) Wight Shrub I Fabaceae Dhoincha Fd Sida acuta Burm. f. Shrub E Malvaceae Kureta M Solanum sisymbriifolium Lamk. Shrub E Solanaceae Kanta-begun M Tabernaemontana divaricata (L.) R. Br. ex Roem. & Schult. Shrub I Apocynaceae Tagor O Ziziphus oenopolia (L.) Mill. Shrub I Rhamnaceae Jaungli Boroi W Ziziphus rugosa Lamk. Shrub I Rhamnaceae Bon Boroi W Antidesma ghaesembilla Gaertn. Shrub I Euphorbiaceae Khudijam W Grewia nervosa (Lour.) Panigrahi Shrub I Tiliaceae Assar W Achyranthes aspera L. Herb I Amaranthaceae Apang M Ageratum conyzoides (L.) L. Herb E Asteraceae Fulkuri M Alternanthera philoxeroides (Mart.) Griseb. Herb E Amaranthaceae Malancha Shak M Amaranthus spinosus L. Herb E Amaranthaceae Kantakhure M Anisomeles indica (L.) O. Kuntze Herb I Lamiaceae Gobura M Axonopus compressus (Sw.) P. Beauv. Herb E Poaceae Carpet Durba Fd Cheilanthes tenuifolia (Burm.f.)Sw Herb I Pteridaceae Shuklata M Chromolaena odorata (L.) King & Robinson Herb E Asteraceae Bara Shialmuti M Chrysopogon aciculatus (Retz.) Trin. Herb I Poaceae Chorkanta Fd Chrysopogon zizanioides (L.) Roberty Herb I Poaceae Benna Fd Commelina benghalensis L. Herb I Commelinaceae Kanchira M Crotalaria juncea L. Herb E Fabaceae Jhunjhuni M PLANT DIVERSITY, CONSERVATION WORTHINESS AND PEOPLE’S PERCEPTION 285 Name of the species Habit Origin Family Local name Use Crotalaria pallida Aiton Herb E Fabaceae Jhunjhuni M Curculigo orchioides Gaertn. Herb I Liliaceae Tali O Curcuma longa L. Herb I Zingiberaceae Holud M Cyanthillium cinereum (L.) H. Rob. Herb I Asteraceae Kukshim M Cynodon dactylon (L.) Pers. Herb I Poaceae Durba M Cyperus distans L. f. Herb I Cyperaceae Pani Malacha Fd Cyrtococcum accrescens (Trin.) Stapf Herb I Poaceae Not known Fd Cyrtococcum oxyphyllum (Steud.) Stapf Herb I Poaceae Sada kandari Fd Desmodium gangeticum (L.) DC. Herb I Fabaceae Salpani M Desmodium heterocarpon (L.) DC. Herb I Fabaceae Karpo-mpdi M Desmodium laxiflorum DC. Herb I Fabaceae Boro aduulia M Desmodium triflorum (L.) DC. Herb I Fabaceae Kulaliya M Desmodium triquetrum (L.) DC. Herb I Fabaceae Ulucha M Elephantopus scaber L. Herb I Asteraceae Shamdala M Emilia sonchifolia (L.) DC. Herb I Asteraceae Sadimudi M Eragrostis cilianensis (All.) Vignolo-Lutati Herb E Poaceae Dudh Nal M Eragrostis tenella (L.) P. Beauv. ex Roem. & Schult. Herb E Poaceae Koni Ghas Fd Euphorbia hirta L. Herb E Euphorbiaceae Dudhia M Euphorbia hyssopifolia L. Herb E Euphorbiaceae Jungli badam M Fimbristylis rigidula Nees Herb E Cyperaceae Hari tandul Fd Flemingia javanica C.Y. Wu Herb E Fabaceae Bara Salpan M Floscopa scandens Lour. Herb I Commelinaceae Hangsapadi Ghas M Fuirena ciliaris (L.) Roxb. Herb I Cyperaceae Mutha Fd Glinus oppositifolius (L.) Aug. DC. Herb I Molluginaceae Gema Shak V Heliotropium indicum L. Herb I Boraginaceae Hatisur M Hellenia speciosa (J. Koenig) S.R. Dutta Herb I Costaceae Keumul M Hemarthria protensa Steud. Herb E Poaceae Challey Ghas M Hypolytrum nemorum (Vahl) Spreng. Herb I Cyperaceae Kodal patar M Hyptis suaveolens (L.) Poit. Herb E Lamiaceae Tokma M Imperata cylindrica (L.) P. Beauv. var. latifolia (Hook. f.) C. E. Hubb. Herb I Poaceae chon Fd Leersia hexandra Sw. Herb I Poaceae Arali Ghas Fd Leucas aspera (Willd.) L. Herb I Lamiaceae Dandokolosh M Lindernia anagallis (Burm. f.) Pennell Herb I Scrophulariaceae Pani Ghas M Ludwigia prostrata Roxb. Herb I Onagraceae Shayankura M Mimosa diplotricha C. Wright ex Sauv. var. diplotricha Nielsen Herb E Mimosaceae Assam Lajuk O Murdannia elata (Vahl) Brck Herb I Commelinaceae Lamba Murdan M Mimosa pudica L. Herb E Mimosaceae Lojjaboti O Murdannia spirata (L.) Beck Herb I Commelinaceae Sishir Murdan M Nelsonia canescens (Lamk.) Spreng. Herb I Acanthaceae Nelson's spurge M Oplismenus compositus (L.) P. Beauv. Herb I Poaceae Ghas Fd Panicum brevifolium L. Herb I Poaceae Ghas M Panicum notatum Retz. Herb E Poaceae Panita Ghas Fd Panicum paludosum Roxb. Herb I Poaceae Ghas Fd Panicum repens L. Herb I Poaceae Dhani Ghas M Paspalum conjugatum Bergius Herb E Poaceae Moisshya Ghas Fd Paspalum scrobiculatum L. Herb I Poaceae Goicha M 286 ISLAM et al. Name of the species Habit Origin Family Local name Use Pennisetum poystachion (L.) Schult. Herb E Poaceae Shuti Ghas M Phyllanthus niruri L. Herb E Euphorbiaceae Bhui Amla M Physalis minima L. Herb I Solanaceae Ban Tepari M Rhynchospora rubra (Lour.) Makino Herb I Cyperaceae Lalthuti Ghas M Rhynchospora rugosa (Vahl) Gale Herb E Cyperaceae Kadathuti Ghas M Richardia scabra L. Herb E Rubiaceae Nakal Ipecac M Saccharum spontaneum L. Herb I Poaceae Kash O Schoenoplectus articulatus (L.) Palla Herb E Cyperaceae Choto Chenchra M Scleria levis Retz. Herb I Cyperaceae Chas Ghas Fd Scleria oblata S.T. Blake Herb I Poaceae Rialata Ghas Fd Scleria terrestris (L.) Fassett Herb I Cyperaceae Dharalik M Scoparia dulcis L. Herb E Scrophulariaceae Chinigura M Spermacoce latifolia Aublet Herb E Rubiaceae Ban dhatura M Sphagneticola trilobata (L.) Pruski Herb E Asteraceae Tinkona Daisy M Spilanthes acmella (L.) L. Herb I Asteraceae Surjakoynna M Strobilanthes hirta (Vahl) Blume Herb I Acanthaceae Burir Chul M Synedrella nodiflora (L.) Gaertn. Herb E Asteraceae Nak Phul M Tephrosia purpurea (L.) Pers. Herb I Fabaceae Bo Nil M Tridax procumbens L. Herb E Asteraceae Tridahara M Triumfetta rhomboidea Jacq. Herb I Tiliaceae Bon Okra M Uraria lagopus DC. var. neglecta (Prain) Ohashi Herb I Fabaceae Bonkathi M Urena lobata L. Herb I Malvaceae Okra M Zingiber montanum (Koen.) Dietr. Herb I Zingiberaceae Am Ada M Christella dentata (Forssk.) Brownsey & Jermy Herb E Theypteridaceae Bish Deki M Diplazium esculentum (Retz.) Sw. Herb I Athyriaceae Neutenga shak M Lygodium flexuosum (L.) Sw. Herb I Lygodiaceae Lata Dheki M Nephrolepis biserrata (Sw.) Schott. Herb I Nephrolepidaceae Bagan Dheki M Pteris pellucida Presl Herb I Pteridaceae Dheki Shak M Bambusa bambos (L.) Voss Herb I Poaceae Boro Bansh T Bambusa vulgaris Scharad. ex Wendl. Herb E Poaceae Jai Bansh T Cajanus scarabaeoides (L.) Thouars Climber I Fabaceae Lata Arhor V Coccinia grandis (L.) Voigt Climber I Cucurbitaceae Telakucha M Dioscorea belophylla (Prain) Voigt ex Haines Climber I Dioscoreaceae Shora Alu M Dioscorea bulbifera L. var. bulbifera L. Climber I Dioscoreaceae Gonj Alu M Dioscorea bulbifera L. var. sativa (Hook. f.) Prain Climber I Dioscoreaceae Gen Alu M Dioscorea hamiltonii Hook. f. Climber I Dioscoreaceae Miltoni Alu M Dioscorea pentaphylla L. Climber I Dioscoreaceae Jhum Alu M Dioscorea tomentosa Koen. ex Spreng. Climber I Dioscoreaceae Kenda M Dysolobium pilosum (J.K. Klein ex Willd.) Maréchal Climber I Fabaceae Dudhi lata M Merremia hederacea (Burm. f.) Hallier f. Climber I Convolvulaceae Kaladana M Mikania cordata (Burm.f.) B.L.Rob. Climber E Asteraceae Assam-lata M Mucuna pruriens (L.) DC. Climber I Fabaceae Alkushi M Mukia maderaspatana (L.) M. Roem. Climber I Cucurbitaceae Gol Akri M Operculina turpethum (L.) S. Manso Climber I Convolvulaceae Dudh Kolmi M Smilax ovalifoila Roxb. Climber I Smilacaceae Kumarilata M Smilax perfoliata Lour. Climber I Smilacaceae Kumarilata M Stephania japonica (Thunb.) Miers Climber I Menispermaceae Nimukha M Tinospora cordifolia (Willd.) Hook. f. & Thoms. Climber I Menispemaceae Ghora Gulancha M Lygodium microphyllum (Cav.) R.Br. Climber I Lygodiaceae Lata Dheki M PLANT DIVERSITY, CONSERVATION WORTHINESS AND PEOPLE’S PERCEPTION 287 Name of the species Habit Origin Family Local name Use Dalbergia volubilis Roxb. Climber I Fabaceae Bara siriskath M Derris cuneifolia Benth. Climber I Fabaceae Shagun M Derris scandens (Roxb.) Benth. Climber I Fabaceae Kali-lata M Spatholobus parviflorus (Roxb. ex DC.) O. Kuntze Climber I Fabaceae Hati Lata M Hemidesmus indicus (L.) R. Br. Climber I Apocynaceae Ananta Mul M Ipomoea aquatica Forssk. Climber I Convolvulaceae Kolmi V Merremia hirta (L.) Merr. Climber I Convolvulaceae Ghena lota M Merremia umbellata (L.) Hallier f. Climber E Convolvulaceae Sada Kolmi M Pueraria montana (Lour.) Merr. Climber E Fabaceae Kudzu M Exotic Plant Species The current study revealed that 25% of recorded plant species are exotic whereas 75% are indigenous or native. As the forest is dominant by a single tree, the number of exotics and their abundance have been found to be very less. These exotics such as Parthenium hysterophorus, Mimosa pudica, Mikania cordata, Chromolaena odorata are relatively common in the forest edges and near the roads, not inside the forest vegetation. Besides, different pockets inside the forest and many canals and water bodies also contain these plants in their banks in more or less amount. Though the invasion hasn’t gained that much momentum, considering the aspects of accelerated fragmentation and disturbance in the forest, the exotics might be a serious problem in the near future. While Rahman et al. (2010) documented the presence of exotic species like Acacia auriculiformis, Eucalyptus camaldulensis, and A. mangium in other Sal forests of central Bangladesh, the Purbachal Sal Forest remains free of these species. Unlike in some areas where these exotics have been intentionally planted, the Purbachal Sal Forest has not adopted such practices. Quantitative Attributes of Tree Species Importance Value Index (IVI) was calculated to determine the predominant tree species in the overall area of study site. According to the analysis, Shorea robusta is the most dominant tree species followed by Albizia procera, Barringtonia acutangula, Cassia fistula, Trema orientale, Ziziphus mauritiana, Albizia julibrisshin, Lagerstroemia speciosa, Zanthoxylum rhetsa and Bridelia tomentosa (Table 2). Table 2. Top 10 tree species based on IVI. Species RD RF RA IVI Shorea robusta 85.9 42.9 90 219 Albizia procera 1.88 4.56 1.5 7.94 Barringtonia acutangula 0.67 3.77 2.11 6.56 Cassia fistula 5.22 0.47 0.05 5.74 Trema orientalis 0.6 3.62 0.31 4.53 Ziziphus mauritiana 0.49 3.62 0.12 4.23 Albizia julibrissin 0.36 2.67 0.56 3.6 Lagerstroemia speciosa 0.32 2.36 0.32 2.99 Zanthoxylum rhetsa 0.33 2.52 0.13 2.97 Bridelia tomentosa 0.24 2.36 0.18 2.79 288 ISLAM et al. The top 10 most abundant tree species, based on number of individuals, on overall research area are given in Fig. 2. Shorea robusta is the most abundant tree species followed by Albizia procera, Barringtonia acutangula, Trema orientalis, Ziziphus mauritiana, Albizia julibrissin, Lannea coromandelica, Zanthoxylum rhetsa, Lagerstroemia speciosa and Bridelia tomentosa. Fig. 2. Top 15 species with individuals. The Sal tree, S. robusta, asserts its dominance with an unparalleled Importance Value Index (IVI) of 219. This metric, a measure of a species' relative abundance, frequency, and dominance within a community, underscores the Sal's exceptional status. In stark contrast, the other species ranked among the top 10 most-IVI-containing species pale in comparison, with IVIs that barely reach 10. The Sal's dominance actually shapes the very fabric of the forest ecosystem. For example, while the Sal trees flourish in the forest area, their less competitive counterparts i.e. other species are relegated to the margins, often confined to areas that have been disturbed by human activities. Though the number of associate trees is greater in Madhupur Sal Forests than in Purbachal Sal Forest, the dominance of Sal in Purbachal exceeds that of Madhpur (IVI 120.99) (Malakar et al., 2010). In case of Bhawal Sal Forest, the dominance of Sal is quite high (277.94), surpassing both the Purbachal and Madhupur Sal Forests (Rahman and Vacik, 2010). Diversity of Tree Species Analysis of the Sal Forest’s tree species diversity revealed moderate species richness (Margalef's Index: 4.77) contrasting with low diversity (Shannon-Wiener Index: 0.61). This pattern suggests a community with a moderate number of species, but one species, the dominant Sal (Shorea robusta), exhibiting significantly higher abundance compared to others. This dominance is further supported by the low Shannon-Wiener index, which incorporates both species richness and evenness of abundance. While a moderate Simpson's Diversity Index (0.178) might suggest otherwise, the lower value in this context likely reflects the presence of a highly abundant species alongside a less abundant long tail of species. This observed pattern of moderate richness with low diversity is commonly documented in sal forests. Potential explanations for this phenomenon include efficient regeneration strategies of Sal trees, shade tolerance allowing them to thrive under their own canopy, or a combination of these factors. PLANT DIVERSITY, CONSERVATION WORTHINESS AND PEOPLE’S PERCEPTION 289 Quantitative Attributes of Shrub Species Among the 32 shrub species recorded from the study area, based on IVI, the most dominant shrub plant is Melastoma malabathricum, Phyllodium pulchellum, Solanum sissymbrifolium, Clerodendrum viscosum, Glycosmis pentaphylla, Calamus guruba, Grewia nervosa, Abroma augusta, Sesbania bispinosa and Lippia alba (Table 3). Table 3. Top 10 shrub species based on IVI. Name of the species RD RF RA IVI Melastoma malabathricum L. 13.53 13.9 2.94 30.42 Phyllodium pulchellum (L.) Desv. 6.58 5.64 3.54 15.76 Solanum sisymbrifolium Lamk. 5.48 5.04 3.3 13.83 Clerodendrum viscosum Vent. 5.48 4.45 3.74 13.67 Glycosmis pentaphylla (Retz.) A. DC. 4.75 5.93 2.43 13.12 Calamus guruba Buch.-Ham. ex Martius 4.75 3.26 4.42 12.43 Grewia nervosa (Lour.) Panigrahi 4.2 5.64 2.26 12.1 Abroma augusta (L.) L. f. 4.02 2.08 5.87 11.97 Sesbania bispinosa (Jacq.) Wight 1.83 0.59 9.34 11.77 Lippia alba (Mill.) Briton et Wilson 4.02 4.75 2.57 11.34 According to the analysis, the top 15 most abundant shrub species in the study area are Melastoma malabathricum, Phyllodium pulchellum, Clerodendrum viscosum, Solanum sisymbrifolium, Calamus guruba, Grewia nervosa, Abroma augusta, Lippia alba, Cajanus cajan, Morinda angustifolia, Croton caudatus, Sida acuta, Ziziphus oenopolia, Bridelia stipularis and Ziziphus rugosa. It is noteworthy that the IVI of M. malabathricum is second to Sal (Shorea robusta) when compared to both trees and shrubs, highlighting its relative abundance within the forest community. The presence of a single shrub species, M. malabathricum, with such a high IVI alongside Sal trees suggests a possible niche specialization or competitive advantage that allows it to thrive in the understory of the sal forest. Further investigation into the ecological adaptations of M. malabathricum could provide insights into how it coexists with Sal trees and other shrub species. Herb Species of Purbachal Sal Forest A total 88 herb species belonging to 27 families have been found in the study sites. The scientific name, common name, family, habit, origin and uses were all recorded in the list (Table 1). All plant species in the families, are not equally represented. In this instance, 5 families represent 62% of all species, whereas the remaining 22 families represent 42%. Poaceae is the largest family followed by Fabaceae, Cyperaceae, Asteraceae and Commelinaceae. People’s Perception One hundred and eight participants were selected for interviews from a variety of backgrounds, including retired and incumbent govt. officers, businessmen, private job holders, housewives, teachers, and plot owners. Each interviewee was asked nine close-ended questions in the form of a questionnaire. Each question resulted in a different percentage of positive and 290 ISLAM et al. negative feedback. Moreover, they helped in pointing out many challenges of managing Purbachal Sal Forest and also in suggesting recommendations that were duly noted during the interviews. The public survey exposes a deep concern for the Purbachal Sal Forest's health. The presence of invasive exotic plants is overwhelmingly disapproved of (90%), highlighting public awareness of the threat they pose. There is near-unanimous agreement (95%) on the importance of consulting environmental specialists for managing plant diversity, reflecting a public desire for professional guidance. Stricter enforcement of laws to protect the forest from human activities like cutting and habitat destruction finds strong support (over 90%), demonstrating public awareness of the anthropogenic pressures on the forest. While nearly three-quarters (76%) see a role for local communities in conservation efforts, a significant minority is unsure, suggesting a need for outreach programs to raise awareness and encourage participation. Public opinion is unanimous (100%) on the need for the government to allocate more resources towards forest protection and management. Reforestation programs that focus on planting native species are overwhelmingly endorsed (89%), aligning with the concern over invasive plants and emphasizing the public's desire to restore the forest's natural heritage. Finally, over three-quarters (77%) believe the loss of the Sal Forest would significantly impact the local climate and ecosystem, highlighting public understanding of the critical role the forest plays in environmental stability. In conclusion, the survey reveals a clear public mandate for protecting the Purbachal Sal Forest. By acknowledging these concerns and incorporating public sentiment into conservation strategies, policymakers and forest managers can develop more effective and well-supported plans for safeguarding this vital ecosystem for the future. Threats to Plant Diversity in Purbachal The Purbachal Sal Forest is threatened by multifaceted problems. Invasive alien species like Chromolaena odorata, Mikania cordata, Mimosa pudica, Parthenium hysterophorus, Sphagneticola trilobata, and Acacia auriculiformis are outcompeting native plants, disrupting the forest’s ecosystem balance. Habitat destruction caused by urbanization, deforestation, and unsustainable practices like firewood collection and agricultural expansion is further exacerbating the problem. The clearing of land for various purposes, including infrastructure development and housing, is leading to significant deforestation. Additionally, the dumping of waste is polluting the forest and harming its biodiversity. These combined factors pose a serious threat to the forest's ecological integrity and its ability to provide essential services. Recommendations The Purbachal Sal Forest, despite its promising regeneration as evidenced by its high tree density, faces significant challenges posed by invasive species and the uneven distribution of fruit- bearing trees. To address these issues and ensure the forest's long-term health, a comprehensive management plan is essential. This plan should incorporate strategies such as mixed-species regeneration in forest pockets, targeted planting of some wildlife-supporting trees, effective control of invasive species, active community involvement, stricter enforcement of forest laws, and involvement of expert in managing the forests. By implementing these measures, the Purbachal Sal Forest can be effectively protected and its biodiversity could be enhanced, safeguarding this vital ecosystem for future generations. Acknowledgement The first author acknowledges the NST fellowship provided by the Ministry of Science and Technology, Government of the People’s Republic of Bangladesh. PLANT DIVERSITY, CONSERVATION WORTHINESS AND PEOPLE’S PERCEPTION 291 References Ahmed, Z.U., Begum, Z.N.T., Hassan, M.A., Khondker, M., Kabir, S.M.H., Ahmad, M., Ahmed, A.T.A., Rahman, A.K.A. and Haque, E.U. (Eds). 2008a. Encyclopedia of Flora and Fauna of Bangladesh, Vol. 6. Angiosperms: Dicotyledons (Acanthaceae – Asteraceae). Asiat. Soc. 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