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© 2020 Conscientia Beam. All Rights Reserved. 

PLANT DIVERSITY AND REGENERATION POTENTIALS IN PROTECTED AREA 
FORESTS OF SIERRA LEONE   

 

 

 Moses Fayiah1+ 
Shikui, Dong2 
Sanjah Singh3 
Roberto Xavier Supe 
Tulcan4  
Kadijatu Sheriff5 
Ibrahim Robinson  
Kargbo6 
Abdulai Barrie7 

 

1,5,6,7Department of Forestry, School of Natural Resources Management, Njala 
University, Sierra Leone. 

  
2State Key Laboratory of Water Environment Simulation, School of 
Environment, Beijing Normal University, Beijing, China; Department of 
Natural Resources, Cornell University, Ithaca, NY, USA. 

 
3Biodiversity and Climate Change Division, Indian Council of Forestry 
Research and Education, Dehradun, India. 

 
4State Key Laboratory of Water Environment Simulation, School of 
Environment, Beijing Normal University, Beijing, China. 

 

 

 
(+Corresponding author) 

 ABSTRACT 
 
Article History 
Received: 15 September 2020 
Revised: 8 October 2020 
Accepted: 30 October 2020 
Published: 18 November 2020  
 

Keywords 
Protected areas 
Regeneration 
Sierra Leone 
Flora biodiversity 
Seedlings 
Saplings & Trees. 

 
Protected areas (PAs) around the globe are considered a reservoir for biodiversity 
conservation and an engine for ecosystem function and services. The regeneration 
potential of tropical forests in (PAs) is crucial to plant diversity survival and 
conservation, amid climate change in the 21st century. The PAs conservation and 
management status of Sierra Leone is uncertain. This study assessed the seedlings, 
saplings, and trees species diversity, abundance, richness and regeneration status of 
tropical forests in four PAs across Sierra Leone. We sampled 60 quadrats in total with 
each having a dimension of 20m × 20m. We found only a few new species with good 
regeneration potential in all the forest PAs were assessed, indicating that the resilience 
of these forests is quite low in the face of anthropogenic activities especially shifting 
cultivation and logging. Plant diversity index and soil factors were positively 
correlated, indicating that a decrease or increase in soil physical and chemical 
properties could affect speciation. The results show that diameter class distribution 
mainly falls within the 0-30cm category. Furthermore, abiotic factors (like precipitation 
and temperature), species richness, ecosystem complexity and over story were predicted 
to have influenced the regeneration and flora diversity of the PAs forests significantly. 
The results imply that PAs in Sierra Leone are going through serious exploitation and 
as such, plant diversity and richness is low and the regeneration ability is poor due to 
weak conservation strategies and approaches. It recommended that strategic planning 
and forest enrichment policies be instituted to mitigate future PAs forest exploitation.  
 

Contribution/Originality: This study is one of the few studies that investigate plant diversity, regeneration 

and soil properties across PAs in Sierra Leone. The research contributes to the existing literatures in PAs and their 

ecosystem characteristics. The article concludes that; PAs in Sierra Leone plant diversity and richness and 

regeneration ability is low.  

 

 

Current Research in Agricultural Sciences 
2020 Vol. 7, No. 2, pp. 64-83. 
ISSN(e): 2312-6418 
ISSN(p): 2313-3716 
DOI: 10.18488/journal.68.2020.72.64.83 
© 2020 Conscientia Beam. All Rights Reserved. 

 
 
 

 
 
 

 

 
 
 
 

https://orcid.org/0000-0002-8339-4249
https://www.doi.org/10.18488/journal.68.2020.72.64.83


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1. INTRODUCTION 

Sierra Leone is a small country with a land area of 72,180 (sq. km), situated in the Upper Guinean, which is 

dominated by a lowland forest ecosystem with supposing rich biodiversity and biotic uniqueness in terms of 

endemic and threatened species [1-3]. The coordinates of Sierra Leone (60°55‘-100°14‘N and 100°14‘-120°17‘W) 

are reported to be the ultimate reasons that determine the vegetation and biodiversity of Sierra Leone [2]. The 

tropics of Sierra Leone are among the global tropics that play host to more plant species as compared to any other 

terrestrial ecosystem on earth [4]. Nonetheless, climate change and anthropogenic actions have had great impacts 

on forest resources across PAs in Sierra Leone [5]. Theories have proven that climate change and anthropogenic 

actions, especially in developing countries, affects virtually all aspects of plant diversity, regeneration and growth  

[5, 6]. Climatic factors and anthropogenic activities have resulted in continuous wild species transformations and 

their distribution on a broad scale across the globe due to precipitation regimes, increased accumulation of CO2 in 

the atmosphere, flooding and warm climate [5].  

According to the FAO [7] report, only 5% of Sierra Leone is covered with high forest. The decline in forest 

cover is primarily a result of climate change, anthropogenic actions, weak forest resources protection policy, and the 

11 years civil war period, where in the total forest cover per chiefdoms in Sierra Leone declined from 67.5% to 

57.9% [6, 8]. Although a few studies on plant diversity have been conducted, primarily in Gola Rain Forest 

National Park a well-protected park in the eastern part of the country, the extensive literature on plant diversity, 

and regeneration status of plant species in Sierra Leone is grossly scanty and most times unavailable. As noted by 

Norden, et al. [9] the human-impacted tropics face a critical shortage of ecosystem dynamics understanding and 

information. The availability of forest resources information and ecosystem dynamics understanding will give a 

platform for sustainable planning and management of PAs forests in Sierra Leone. The most comprehensive 

inventory of vegetation study of Sierra Leone, titled Tress of Sierra Leone by Savill and Fox [10] is dated back to 

1967. Reports from comprehensive research done by different authorities [2, 11, 12] affirmed that plant diversity 

information of Sierra Leone is incomplete with no reliable data on species status of PAs except Gola Forest 

National Park.  

Wadsworth and Lebbie [13] recently posed a question of what happened to the forests of Sierra Leone?. 

Numerous researchers reported the impacts of natural drivers such as climate change and human drivers such as 

war and land-use change as degradation culprits on forest resources and diversity decline in Sierra Leone [8, 14, 

15]. Jones, et al. [16] recently employed a strategy to detect rule-breaking using optimal monitoring approach on 

the Gola Forest National Park Sierra Leone using field data. This approach gives an insight on changes occurring 

in the protected area over time due mainly to hunting. Similarly, Wilebore, et al. [17] adopted a randomized 

control trial to assess the influence of unconditional livelihood payment to indigenous communities on land use 

situated outside of Gola Forest National Park in Sierra Leone.  

A comprehensive review done by Mascia and Pailler [18] uncovered massive PAs downsizing, downgrading 

and degazettement in 89 instances across 27 countries from 1900.  PAs are generally believed to be the bedrocks of 

international and national biodiversity protection and conservation strategies [19] especially in Africa. Mascia and 

Pailler [18] referred to PAs as the ―foundation of global efforts to conserve biological diversity”. They are the backbones 

for biodiversity conservation and at the same time supporting people‘s livelihood.  Most notably at the local level 

[20] PAs are places of natural development that deserve ecological restoration [19]. An estimate of PAs by IUCN 

and UNEP [21]; Mascia and Pailler [18] and United Nations [22] suggested that there are more 122, 000 

designated PAs occupying around 12% of the global land surface.   

Biodiversity in the PAs worldwide is under severe anthropogenic stresses [23-27] and climate change threats 

[28, 29] with developing countries being more prone to threats than developed nations. The continuous growth in 

population coupled with rapid economic development, as well as the escalating per-capital impacts in the previous 

century have led to massive degradation of the PAs [30, 31]. Even though the destruction of natural resources in 



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the PAs is minimal as compared to nearby unprotected forests, many protected areas remain mere ‗paper parks‘. 

Most of the world‘s flagship protected (World heritage sites) areas are being threatened increasingly by 

anthropogenic activities due to the lack of adequate protection [19, 32]. 

 In the context of Sierra Leone, population growth, unemployment, mining, shifting cultivation and other forms 

of land use activities have contributed significantly to the degradation and loss of biodiversity in PAs with such 

activities threatening the planet‘s life support system [33] potentially affecting ecosystem health [34]. There are 

48 designated PAs, in Sierra Leone including forest reserves, wildlife sanctuaries, national parks and conservation 

sites, covering 284, 592ha or 4% of Sierra Leone‘s territory [11, 35, 36] relatively less than the global average of 

6.2% and Africa‘s average of 5.9% respectively [37]. However, only 29 of Sierra Leone PAs are under strategic 

management [2]. From 1967 to date, much biodiversity in Sierra Leone has been lost, leading to many plant species 

becoming extinct or on the verge of extinction [2]. In the policy dimension, biodiversity and tropical forests of 

Sierra Leone are protected by the country‘s Biodiversity Strategy and Action Plan [11].  However, the overlap of 

the mandate by other ministries renders the efficient protection of PAs areas in Sierra Leone challenging and 

uncertain [38]. 

Natural regeneration of any forest is the biological and reproductive process that facilitates the replacement 

and sustainable growth of that forest over time [6, 39-42]. The abundance of seedlings, saplings and trees greatly 

determine the regeneration potential of a forest [6]. The assessment of life stages of plant species helps in 

determining the relative importance of their niche as well as their community assembly neutral processes [9, 41].  

Knowing the regeneration status of flora biodiversity of any PAs helps in the design of effective interventions 

and adaptive management, improving conservation communication and management strategies. In order to narrow 

the decades-long knowledge gap of plant diversity and regeneration status, we conducted surveys in four protected 

areas with aims to address the following research questions: what is the regeneration status of plant diversity in 

protected areas of Sierra Leone? Could the current plant diversity in Sierra Leone be sustained for another decade? 

Does the soil type affect plant diversity and regeneration across protected areas in Sierra Leone? What are the 

driving factors of poor species regeneration? The answers to these research hypotheses can provide vital 

information about the flora biodiversity, plant regeneration status, and the relationship between plant diversity and 

soil properties of the protected areas.  

 

2. MATERIALS AND METHOD  

2.1. Study Location 

The research was carried out in four forest PAs including forest reserves and national parks, which are 

Western Area Peninsular National Park (17,800ha) in the West; Kangari Hills forest reserve (8,537ha) in Central 

North; Kambui forest reserve (21,213ha) in the East and Kasewe forest reserve (2,333ha) in the South of the country 

respectively Figure 1.  

These four PAs were selected based on their strategic geographical locations, vegetation and protected area 

status as well as their biotic activity and settlement proximity characteristics. The elevation of these protected areas 

ranges from 100m to 700m Table 1. All four PAs fall under category IV of the International Union for the 

Conservation of Nature (IUCN) designation [43] and cover five major ecosystems in Sierra Leone, i.e., low land 

tropical rain forests; montane forests; coastal marine; savanna woodlands, and freshwater & wetlands [3]. Sierra 

Leone‘s climate is tropical humid with two pronounced seasons, i.e., the dry season from November to April and the 

wet season from May to October. 

Species and family dominance are report in Table 1 together with the region and elevation of each study 

location Tables describes. Additionally, the geographical location of each study area is recorded in Table 1.   

 



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Figure-1. Map of Sierra Leone showing Districts and sampling sites (forest reserves). 

 
Table-1. Location and dominant species in study areas. 

Name  St Geographic location  Al (asl) Dominate 
species 

Dominate. 
family  

Region  

 
WAF  

NP N 08⁰ 07' 08.7''- W 012⁰ 
04'23.1' 

N 08⁰ 20' 55.7''- W013⁰ 10' 
40.2'' 

50-300m Phyllocosmus 
africanus       

Euphorbiaceae West 

 
Kangari 
F 

FR N 08⁰ 20' 55.5'' -W013⁰ 10' 
40.2'' 

N08⁰ 31' 40.2'' - W011⁰ 40' 
10.4'' 

55-550m Heriteria utilis   Euphorbiaceae Central/North 

 
Kambui 
F  

FR N 07⁰ 31' 40.1'' -W011⁰ 40' 
01.6'' 

N07⁰ 54' 48.8''-  W011⁰ 13' 
45.8'' 

132-
600m 

Diospyros 
cooperi 

Ebanaceae East 

 
Kasewe F  

FR N 08⁰ 07' 09.1''- W012⁰ 04' 
22.9'' 

N08⁰ 19' 24.8'' - W012⁰ 10' 
28.4'' 

100-
300m 

Guibourtia 
copallifera 

Euphor piaceae South 

Note: F= Forest; NP= National Park; FR= forest reserves; Al= Altitude; D= Dominant; St= Stat. Source: Researcher, 2019. 

 
Table-2. Temperature and precipitation in Sierra Leone. 

Climate Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Anu 

Av Max 
Tem 

29.9 30.3 30.9 31.2 30.9 30.1 28.7 28.4 29 29.9 30.1 29.7 29.9 

Av Min 
Tem 

23.8 27.6 24.4 24.8 24.4 23.6 23.1 23 23.1 23.4 24 24.1 23.8 

Av Prep mm 3.4 3.6 12.5 46.9 177.2 323 734.3 791.1 484.1 265.8 87.9 15.9 2945.3 
Note: Av= Average, Max= Maximum, Min=Minimum and Prep= Precipitation. 
Source: ClimTemp.com (http://www.freetown.climatemps.com/temperatures.php). 

 

2.2. Vegetation Sampling and Analysis  

The vegetation was sampled from four protected forests in Sierra Leone from December 2018 to March 2019. 

Random sampling was carried out as per [44, 45]. Sixty quadrats the sizes of 20 m × 20 m2 were laid randomly in 

the forests, with 15 quadrats from each PAs. In each quadrat, two subplots the size of 3 m × 3 m and 1 m × 1 m2 



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were nested to enlist the saplings and seedlings. In each quadrat, plant individuals were considered as trees when 

their diameter at breast height (Dbh) was ˃10cm Dbh, as saplings when their Dbh was ≤ 10 cm and as seedlings, 

when their DBH was ≤ 3m [46]. The flora vegetation and analysis followed acceptable global flora biodiversity 

assessment in tropical forests protocols as per [45, 47-49]. A checklist of trees species was prepared using the 

―Trees of Sierra Leone‖ [10]. The diameter at breast height =1.3m was recorded for each tree above 10cm for the 

determination of basal area and cover by extension r2 (the radius). Importance value index (IVI), density, frequency, 

and the basal area was calculated based on Mishra. [45] formulae and regeneration, as described by Singh, et al. 

[50] and Shankar [51].  

 

2.3. Soil Sampling and Analysis 

The soil in the study areas was moderately acidic with a loamy, sandy texture Table 3. Samples of soil were 

collected from three points within the quadrats viz a vice two opposite corners and in the Centre at a 0-15cm depth, 

mixed and placed in a soil sample polythene bag. The combined samples from each quadrat in each site were 

thoroughly mixed to form one composite soil sample. The samples were analyzed in the laboratory as per [52, 53] 

for both physical chemical soil parameters as seen in Table 3.  

 

2.4. Formula of Different Diversity Indices used to Analyze Data 

I. Simpson Diversity index:                                                                                                                                        Eq1 

𝐷 = 1 - Ʃ (𝑛-1)  

                 (𝑁-1) 

where, 

 n = refers to the number of each individual species. 

 N = refers to a total number of all individual species. 

II. Shannon Diversity index:                                                                                                                                  Eq2 





S

i
ii PPSHDI

1

)ln(  

Where:  

H= refers to Shannon-Wiener Index of diversity, Pi = the individual proportion of a species, S = Species number in 

the community, Σ = summation symbol, In = Natural logarithm to the base e. 

III. Evenness diversity                                                                                                                                            Eq3 

 

Where H represents the Shannon diversity index. 

S means the number of species. 

N= the total number of individuals in a given community. 

ni= the number of individual species in the ith species. 

IV. Equitability J:                                                                                                                                               Eq4 

E= H/Ins 

Where H= Shannon diversity index was divided by the logarithm of the number of given taxa. 

3. RESULTS  

3.1. Floral Composition in Different PAs 

Across the four protected areas, a total of 129 species from 53 families were recorded Appendix A. Specifically, 

there were 68 species (trees, saplings, and seedlings) from 38 families of vascular plants in Kangari forest; 69 species 

from 34 families in Kambui forest reserve; 46 species from 27 families in Kasewe reserve, and 50 species from 31 



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families in Western Area reserve Table 4. The dominant tree species in the four PAs were Diospyros cooperi in 

Kambui, Phyllocomos africanus in Kangari, Heriteria. Utilis in Kasewe and Guibourtia copallifera in Western Area 

forest national park, respectively Table 1. The pH of the four sites ranged from 4.11 to 4.99, with a mean of 4.64 

pH. Soil Electrical Conductivity ranges from 11.35 to 30.00, with a mean value of 19.34 (μS/cm). The highest total 

Nitrogen value was (1.19 %) while the Western Area Forest recorded the least (0.35%). Total P was the highest in 

the Western Area Forest (119.00 mg/kg) and the lowest (99.00 mg/kg) in Kasewe forest. 

 

 
Figure-2. Total number of species per sampling plot in the four PAs. 

 

Kambui and Kangari forest recorded the highest number of species while Kasewe recorded the lowest Figure 2. 

Both Western area and Kasewe forest reserve recorded 50 individual trees species.  

 

 
Figure-3. Average number of species diversity per PAs vegetation stages. 

 

Trees had the highest number of species followed by sapling and seedlings. Western area forest however 

recorded the lowest number of species in all vegetation stages Figure 3.  



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Figure-4. Species abundance as per trees diameter at breast height (DBH). 

 

Kangari forest recorded the highest number of trees species within 10-30cm diameter at breast height range 

Figure 4. In all four study sites, the highest densities of species were observed in the lower class of DBH (0-30cm) 

 

 
Figure-5. Species richness per individual species in protected areas. 

 

 
Figure-6. Species richness per sampling sites. 

 



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The richness of species per individual and sampling sites is demonstrated in Figures 5 & 6. Kambui forest 

recorded high species richness as compared to the other forests. Alternately, Kasewe forest reserve recorded the 

lowest species per site and individual pool.   

 

 
Figure-7. Species richness against elevation. 

 

A statistical significance at (< 0.05) was detected between species richness and altitude Figure 7. The figure 

demonstrates that Kangari and Kambui forest had higher species richness and elevation.   

 

 
Figure-8. Relatioship between sampling sites and quadrats. 

 

The relationship between sampling sites and quadrats is shown in Figure, 8. The figure shows the distribution 

of sampling quadrat per forest reserve. The figure clearly explain the sampling sites and how randomly the 

quadrats were laid in each site Figure, 8.   

 



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Figure-9. Plant multi-diversity indices of plants. 

 

The Shannon and Simpson diversity was higher in Kangari and Kambui forest at a (<0.05) significance level 

Figure 9. However, the trend was different with species evenness index, Berger index, and J evenness.  

 

 
Figure-10. Regeneration status of seedlings, saplings and trees. 

 

Majority of plants were seen in the tree stage while only few were observed in the seedling stage Figure 10. 

The mature trees species dominates in all four protected areas. Only 12-15% of trees showed a good regeneration 

potential across the four study sites Figure 10.  

 

 

 



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Table-3. Physicochemical parameters of the soil in the study sites. 

Sample  Kambui  Forest Kangari Forest Kasewe Forest Western Area Forest 

pH 4.11 4.94 4.51 4.99 

EC (μS/cm) 20.00 11.35 30.00 16.00 

% OC 4.20 3.40 2.20 4.70 
% N 0.11 0.16 0.12 0.23 
Ava. P (mg/kg) 8.10 6.30 5.50 4.00 
Exc. K (mg/kg) 103.5 94.8 94.8 77.4 
Exc. Ca (mg/kg) 25.00 50.00 25.00 25.00 

Exc. Mg (mg/kg) 10.00 80.00 100.00 25.00 
Total P (mg/kg) 102.00 118 99.00 119.00 
Total N % 1.19 0.56 0.77 0.35 

Note: EC= Electrical conductivity; OC= Organic carbon; N= Nitrogen; Ava= Available; P= phosphorus; K= potassium; Ca= Calcium; Mg= Magnesium; 
Exc= Exchangeable.  

 

The soil pH for the four study site was found to be moderately acidic with a loamy sand texture.  The 

exchangeable elements displayed low values in all the forests. The EC ranged from 11.35 to 30.00 μS/cm. 

 

Table-4. Correlations between plant diversity and soil chemical and physical factors. 

Diversity 
parameters 

 Shannon diversity Soil chemical and physical factors 

Richness Trees Sap Seed TP TN OC Ca K Mg pH EC 

Richness 1            
Shannon, Trees .823 1           

Shannon, Sapling .950 .695 1          
Shannon, 
Seedling 

.835 .999** .722 1         

Total P    (TP) .140 .493 -.169 .450 1        
Total N   (TN) .490 .148 .738 .195 -.778 1       

Organic Carbon  .322 .795 .207 .788 .553 -.146 1      

Calcium  (Ca) .544 .334 .322 .309 .541 -.254 -.138 1     
Potassium  (K) .604 .107 .789 .146 -.670 .908 -.383 .132 1    

Magnesium (Mg) -.352 -.721 -.370 -.734 -.153 -.241 -.907 .406 .085 1   
pH -.275 -.004 -.562 -.054 .866 -.967* .140 .489 -.792 .281 1  

EC -.610 -.825 -.342 -.797 -.868 .369 -.641 -.669 .246 .344 -.539 1 
Note: **. The correlation is significant at the 0.01 level * significant at 0.05 level (2-tailed).  EC= Electrical conductivity; T.P= Total Phosphorus; T.N=Total 
Nitrogen; O.C= Organic Carbon; Ca=Calcium K= Potassium; Mg= Magnesium; Sap= Saplings; Seed= Seedlings.   

 

Plant richness and diversity of the four sites were positively correlated with soil factors such as total P, total N, 

OC, and exchangeable K, but negatively correlated with exchangeable Magnesium respectively at a significant level 

of P< 0.05 Table 4. 

 
Table-5.  Jaccard Similarity index of seedling, sapling and tree among all the study sites. 

Plant code K1Sa K1 Se K1Tr K2Sa K2 Se K2Tr K3 Sa K3 Se K3 Tr W1Sa W1Se 

K1 Sa 1.00           
K1 Se 0.41 1.00          
K1 Tr 0.23 0.13 1.00         
K2 Sa 0.26 0.26 0.16 1.00        
K2 Se 0.20 0.26 0.15 0.32 1.00       
K2 Tr 0.21 0.12 0.29 0.17 0.21 1.00      
K3 Sa 0.24 0.18 0.12 0.24 0.17 0.14 1.00     
K3 Se 0.24 0.24 0.10 0.24 0.17 0.08 0.39 1.00    
K3 Tr 0.12 0.09 0.19 0.16 0.15 0.21 0.28 0.18 1.00   
W1 Sa 0.26 0.19 0.11 0.19 0.18 0.14 0.24 0.19 0.09 1.00  

W1 Se 0.21 0.18 0.16 0.31 0.21 0.14 0.23 0.18 0.13 0.33 1.00 
W1 Tr 0.20 0.06 0.32 0.08 0.09 0.28 0.11 0.11 0.20 0.16 0.16 

Note: K1= Kambui; K2= Kangari; K3 =Kasewe; W1 = Western area; Se=Seedling; Sa=Sapling; Tr=Trees. 
The Jaccard similarity index showed that Western Areas shared 30% similarity with trees of Kambui forest, and 31% similarity with saplings of Kangari 
forest. Similarly, Kambui forest shared 26% sapling and seedling similarity with Kangari forest Table 5. 

 

 



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4. DISCUSSIONS  

Understanding the species composition, biodiversity, and regeneration status of vegetation in PAs is imperative 

in order to implement an effective conservation strategy for any protected forest [41]. Similarly, knowledge of the 

regeneration, composition, structure and function of species diversity and pattern is essential for the conservation of 

undisturbed area is critical for forest ecosystems [54]. This information is a pre-condition for other ecological 

studies [55]. According to FAO [7] estimation only 5% of Sierra Leone is covered with natural forest while the 

rest is either categorized as farm bush or secondary forest. However, Wadsworth and Lebbie [13] refuted this and 

other recent estimate done by various environmental organizations as well as government reports. Also the current 

study is the first in four decades that attempts to assess the flora biodiversity status, regeneration status and 

potential, and distribution of species, as well as soil factors across the four protected areas in Sierra Leone.  

 

4.1. Species Composition in Forest PAs of Sierra Leone 

The density of trees in the four forest PAs in Sierra Leone ranged from 676 to 820 plants per hectare (ha). For 

a protected tropical forest reserve, these figures depict a decline in vegetation due to deforestation and degradation 

[56]. Climatic factors such as precipitation and temperature, and species richness, ecosystem complexity, and over 

story were believed to have influenced the regeneration and flora diversity of the protected area forests significantly 

[5, 6]. Although Sierra Leone experiences only two pronounced seasons, the rainfall, sunshine and temperature 

distributional patterns vary across the four regions. For example, the intensity of rain that fall in the southeast is far 

more than the north. Additionally, anthropogenic activities undertaken across the four PAs contribute greatly to 

the current status of these PAs. However, the frequency of seedlings and saplings in the studied PAs were relatively 

high. The species richness and diversity of plants in these four PAs denoted that these forests are degraded when 

compared to floral biodiversity in the Gola Forest National Park located in the east of Sierra Leone. Laurin, et al. 

[56] at the Gola Forest in East Sierra Leone recorded 133 plant species in a single forest. While Kargbo [57] and 

Bendu [58] recorded 1,320 individuals and 42 plant species in the South East, respectively. Comparing the species 

abundance in the sub-Western African region, Pereki, et al. [59] recorded 258 plant species belonging 63 families 

in Togo. Appiah [60] recorded 40 species from 32 families in a 40ha forest in Ghana. Therefore, less than 70 

species recorded in the four PAs in this study suggest that these PAs are under high biotic and climatic stress. The 

variation in species richness across the four PAs is believed to be linked with their proximity to urban setting, 

anthropogenic pressure and the little or no adequate forest protection measures and policies [2, 61, 62]. Each forest 

displayed a unique dominance in term of species. Our findings were similar with the result of Bendu [58] who 

recorded Guibouria copallifera (45) as the dominant species in Kasewe forest; Fayiah, et al. [63] also recorded 

Nosogodonia papaverifera and Guibourtia copallifera as the dominant species in Kambui forest eastern Sierra Leone. 

Similarly, Mattia, et al. [64] and Bangura [65] recorded Octhnocosmus africanus and Nosogordonia papaverifera as the 

dominant species within Moyamba District in Southern Sierra Leone. The absolute dominance of a single species in 

any given forest showed the attribute of lesser diversity [60, 66].  

 

4.2. Plant Diversity in the Forest PAs of Sierra Leone 

The increase in diversity can increase the regeneration of forests (Malik and Bhatt, 2016). In this study, the 

Shannon diversity ranged from (0-2.8) in the four PAs. These values were comparable to previous studies within 

Sierra Leone and the sub-region. Laurin, et al. [56]; Bangura [65] and Fayiah, et al. [63] recorded Shannon 

diversity ranging from 0- 3.24 for the plants in forest reserves in the East and South of Sierra Leone. However, 

Bendu [58] and Fayiah. and Koroma [67] reported lower Shannon diversity index of 0.75 and 0.96 from a study 

within Moyamba District Southern Sierra Leone. In the sub-region, Aigbe, et al. [68] reported Shannon values of 

3.827 and 3.795 for plants in two forest reserves in Nigeria. Appiah [60] recorded a mean Shannon index of 4.52 for 

the plants in different forest PAs, while Gatti, et al. [66] recorded Shannon values of 4.23; 4.26 and 4.35 for the 



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plants in three different forests PAs in Ghana. The plant diversity in the forest PAs in Sierra Leone is generally low 

as compared to countries with similar vegetation in the subcontinent. This may be attributed to the nature of 

anthropogenic activities, ecological degradation and climate change [60, 63]. Moreover, the changes in soil 

properties may also significantly affect tree species richness and abundance [12, 69].   

 

4.3. Similarity and Difference of Saplings, Seedlings and Trees in the Forest PAs of Sierra Leone 

The Jaccard similarity index showed that most sites had common species. The Western area contained 30% 

similar trees species with Kambui forest and 31% similar sapling species with Kangari forest. Kangari showed 26% 

of similar sapling and seedlings with Kambui forest species. These findings were in agreement with Fayiah.., et al. 

[70] results that recorded 26% similarity between species from Kasewe forest and that of a community riparian 

forest in Moyamba District. The similarity of species among sites could be connected with soil type, soil pH, soil 

texture, soil nutrients and climatic patterns [71] as well as the climatic condition. The correspondence analysis 

showed that there was no congruence among tree species and the saplings and seedlings among all the study sites. 

There was an even distribution with high evenness from 0.5 to 0.7 in all the study sites except Kasewe reserve, 

which recorded lower evenness value.  

The proportion of trees with various diameters at breast height classes can predict the growth and stem volume 

status of any given forest. The diameter distributions of the tree species in all the sites in the present study were not 

unique, although the majority of the sizes fell within the range of 0-30cm, which was supported by the Rocky and 

Mligo [72] findings in Tanzania. The diameter class displayed different patterns and exhibited a decrease in 

diameter as the richness of plant species increased [40]. The dominance of smaller class diameter at breast height 

suggested that these forests are undergoing natural regeneration after stresses, as the forests with high density in 

lower size class have the potential to regenerate if proper measures are provided to curb pressures [41].  

 

4.4. Regeneration Status and Potential of Forest PAs in Sierra Leone 

The wealth of any given forest depends much on the regeneration potential of the component species of that 

forest in space and time [73]. Typically, good regeneration potential of a forests is determines by a good number of 

species in all categories, i.e. seedlings> saplings > trees [40, 72]. Similarly, the number of different categories of life 

stages such as trees, saplings and seedlings of diverse species can help in forecasting future changes, regeneration, 

and status of flora biodiversity in any forest [41].  

In this study, the abundance of trees species against saplings and seedlings denoted poor or no regeneration in 

the four PAs. Similarly, Fayiah, et al. [70] recorded a fair regeneration for two forests reserves inventoried in 

southern Sierra Leone. They concluded that the regeneration potential of the two forests ranged from fair to poor 

and that may even worsen if urgent measures are not put in place to curb the rate of forest resource exploitation 

within these two forest areas. In the sub-continent, Rocky and Mligo [72] concluded that native species had better 

regeneration potential than exotic species in Tanzania. Poorter, et al. [74] recorded no regeneration along the 

Liberia and Cote d‘Ivoire border in West Africa. According to numerous researchers [74, 75] these problems have 

been dated back decades. In this study, the majority of species were found in the tree stage depicting non-

regeneration ability, while some species were found in all growth stages. Many factors such as climate change, 

shade tolerance, fire resistance, dormancy ability, and soil properties could be attributed to these phenomena [76, 

77]. On a larger scale, the regeneration of natural forests dramatically depends on both abiotic factors such as 

temperature, rainfall, and soil fertility and biotic factors such as diversity, composition and richness [6].  

 

4.5. Soil Physicochemical factors and Plant Diversity in Forest PAs of Sierra Leone 

Accurate soil information is vital in achieving the sustainable development target 15.3 of eradicating land 

degradation/forest globally [78]. Recent discoveries has noted that accurate soil information is essential in not 



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only forecasting climate change impacts on global food production [79]  but also help in halting forest degradation 

and desertification. The vegetative community and soil chemical and physical factors have been proven to have a 

reciprocal relationship [80, 81]. In recent years, researchers have proven that the floral composition of plants, 

spatial and temporal distribution, and community structure were significantly controlled by the type of soil and 

land creation [71, 82].  

Additionally, other factors influencing soil properties were topography and microclimate [80]. The average pH 

of 4.6 showed that the soil was moderately acidic can affect speciation [71]. This finding agree with the global 

gridded soil information published by Hengl, et al. [78] using machine learning approach. The Soil Grids is a 

global database that predicts standard and accepted numeric physical and chemical properties of soil depth ranging 

from 0-200cm respectively [83].  

 A match exist when comparing global Soil Grids information with national data in terms of physical and 

chemical soil properties in most cases [78]. In general; acidification of soil changes the available soil nutrients in 

many different ways [84]. Medinski [85] and Huston [86] concluded that soil texture, pH, and EC were essential 

indicators for explaining the richness of plant species in forests. The inadequacies of primary and micronutrients of 

soils are common in Sierra Leone, leading to low soil fertility [87]. Palpurina, et al. [71] suggested that the pH of 

the soil should be considered as an essential catalyst of fine-scale floral species richness in the terrestrial ecosystem. 

The low physicochemical property of soil in the study sites is believed to have affected species composition and 

richness as well [71, 78, 82, 85, 87]. In agreement with Gol, et al. [80] we predict that the physical and chemical 

properties of soil may have affected regeneration, density, and diversity of plants in the forest PAs of Sierra Leone.  

 

5. IMPLICATION FOR CONSERVATION 

The findings of this study provide a good insight into the current status of PAs in Sierra Leone. Our findings 

revealed differences between the study sites of four forest PAs in Sierra Leone in terms of species diversity, 

regeneration status, and soil properties. Kambui and Kangari forests protected areas showed richer plant diversity, 

while Kasewe and Western forest PAs showed a lower percentage of plant species in all categories. We found only a 

few new species and other species with good regeneration potential in all the forest PAs, indicating the resilience of 

these forests is quite low in the face of degradation.  

Richness, plant diversity and soil factors were positively correlated, indicating that a decrease or increase in soil 

could affect speciation. The various phytosociological attributes and diversity indices showed that the plant 

diversity status of forest PAs in Sierra Leone is at a crossroad. Abiotic factors (like precipitation and temperature), 

species richness, ecosystem complexity and over story were believed to have influenced the regeneration and flora 

diversity of the protected area forests significantly. Drastic management policies and appropriate strategies are 

urgently needed to prevent the forest PAs from further degradation. The regeneration ability of plant diversity in 

the four PAs was generally poor with the majority of the species in the tree stage. The future survival of PAs in 

Sierra Leone is uncertain, and most tree species are at the risk of extinction. The findings on species regeneration, 

distribution and composition, and diversity in this study may be beneficial for sustainable management of protected 

areas across Sierra Leone and the subregion.  

This study will help policy and decision-makers have an idea of the status of protected forests and the urgency 

needed in tackling their exploitation. Going forward, the timely design and implementation of strategic 

management approaches would save the forest from further degradation in the near future. It will be in the best 

interest of forest resources protection in Sierra Leone if the decades-old 1988 forest protection law is replaced with 

a sound policy that addresses current challenges. Forest protection institutions should be strengthened and given 

political support in carrying out their mandates without any fear. This article serves as a baseline for researchers 

and forest management practitioners in Sierra Leone.  

 



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© 2020 Conscientia Beam. All Rights Reserved. 

Funding: This research was financially supported by the grants from the Second Tibetan 
Plateau Scientific Expedition and Research Program (2019QZKK0307), National Key R&D 
Program of China (2016YFC0501906), Qinghai Provincial Key R&D program (2019-SF-145 & 
2018-NK-A2), Qinghai innovation platform construction project (2017-ZJ-Y20). The authors 
would also thank the anonymous reviewers for their helpful comments. 
Competing Interests: The authors declare that they have no competing interests.  
Acknowledgement: Many thanks is extended to Mr M. Swarray (Botanist) attached to the 
Gola Rainforest National Park in Sierra Leone for trees species identification. Many more 
thanks is extended to authors field researchers assistants, Mr. Mohamed Shaw, Salia P. Sannoh, 
Mr. Edward H. Sama and Mr. Musa M. Swarray for their support in collecting data in the field. 

 

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SUPPLEMENTARY MATERIALS  

 

Figure-1. Diversity index of the four Study area. 

 

Figure-2. Trees DBH and their abundance. 

 

 
Figure-3. H Alpha diversity of the four protected areas. 

 



Current Research in Agricultural Sciences, 2020, 7(2): 64-83 

 

 
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© 2020 Conscientia Beam. All Rights Reserved. 

 
Figure-4. Species Rank and abundance of the four protected areas. 

 

 
Figure-5. Diversity per site and scale. 

 
Figure-6. Cluster diagram of sampling location. 

 

 

 

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