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Assessment of Natural Regeneration Status and Diversity of Tree Species in the Biodiversity Conservation Areas of Northeastern Bangladesh

Md. Habibur Rahman
Department of Forestry and Environmental Science, School of Agricul-ture and Mineral Sciences, Shahjalal University of Science and Technology, Sylhet-3114, Bangladesh;

Md. Abu Sayed Arfin Khan
Department of Forestry and Environmental Science, School of Agricul-ture and Mineral Sciences, Shahjalal University of Science and Technology, Sylhet-3114, Bangladesh; Department of Disturbance Ecology, University of Bayreuth, Bayreuth, Germany.

Bishwajit Roy
Department of Forestry and Environmental Science, School of Agricul-ture and Mineral Sciences, Shahjalal University of Science and Technology, Sylhet-3114, Bangladesh

Most. Jannatul Fardusi
Department of Forestry and Environmental Science, School of Agricul-ture and Mineral Sciences, Shahjalal University of Science and Technology, Sylhet-3114, Bangladesh;

Abstract/ Executive Summary:

A study was conducted at two-biodiversity conservation areas of Northeastern Bangladesh (a part of Sylhet Forest Division) to assess the species composition, diversity and density of natural regeneration of tree species both indigenous and exotic species. Data were collected by stratified random quadrate method during January 2010 to July 2010. Totally 200 circular plots of 2 m×2 m in size had 5 different habitat types of plants namely; forest, roadside, homestead (surrounding forest dwellers house), fallow land and others (canals, streams and tea gardens side), which included a total of 55 regenerating species belonging to 28 families. Meliaceae is the dominant family and shows the highest family importance value (26.3), having six species, followed by Moraceae (24.24). Among the five habitat types, forest (43 species) possess the highest number of species, followed by roadside (23 species). Total 15 exotic species among 9 families and 40 indigenous species with 24 families were recorded. For exotic species, Tectona grandis possess the high-est relative density (11.7%) and relative frequency (10.5%); Senna siamea had highest relative abundance (7.83%). In case of indigenous species, Chickrassia tabularis possess the highest relative density (4.23%) and relative frequency (4%); Dipterocarpus turbinatus had the highest relative abundance(3.92%). Tectona grandis (29.66) and Chickrassia tabularis (10.8) had the highest IVI for exotic and indigenous species respectively. Different diversity indices such as Shanon-Winner diversity index, species diversity index, species richness index, species evenness index, Simpson index and species dominance index, etc. were applied to quantify definite diversity. The regeneration of species associated with low levels of disturbance was in the exotic species. Study suggests that proper protection from human disturbances and scientific management of The online version is available at http:// www.springerlink.com Md. Habibur Rahman1 • Md. Abu Sayed Arfin Khan1,2 • BishwajitRoy1() • Most. Jannatul Fardusi11Department of Forestry and Environmental Science, School of Agriculture and Mineral Sciences, Shahjalal University of Science and Technology, Sylhet-3114, Bangladesh; 2 Department of Disturbance Ecology,University of Bayreuth, Bayreuth, Germany. Email: ahir_sust@yahoo.com Responsible editor: Zhu Hong natural regeneration of two-study forests may lead a rich biodiversity site in the country.

Keywords: Biodiversity; Exotic species; Family importance value; Indigenous species; Quantitative characters

Location: Northeastern Bangladesh (a part of Sylhet Forest Division)

Start Date: 00-01-2010

End Date: 00-07-2010

Program Area: Conservation and Biodiversity

Commodity: Plant

Objectives:

The aim of this study was to assess the natural regeneration composition, status and diversity of tree species in two biodiversity conservation areas namely Khadimnagar National Park and Tilagaor Eco-Park of Northeastern Bangladesh. In both the study sites, the ground is covered with herbs, ferns, bamboo, and rattan. Regeneration is occurring mainly through dispersed seeds from the forest.

Methodology:

Study sites The study was conducted in and around biodiversity conservation areas namely, Khadimnagar National Park (KNP) and Tila-gaor Eco-Park (TGEP). These areas were selected purposively considering their unique geo-physical features in biological di-versity. KNP (N 24º56'−24º58' and E 91º55'−91º59') and TGEP (N 23º55'−25º14' and E 90º55'−92º31') are located at North Sylhet Range-1 in Sylhet Forest Division under tropical evergreen and semi-evergreen bio-geographic zone. KNP was declared as National Park in 2006, which was formerly known as Khadim-nagar Reserve Forest. Total area of KNP is 679 ha, surrounded by three tea gardens, and submerged with several watersheds locally known as “chara”. TGEP was declared as Eco-Park in 2006 with a total area of 45.35 ha. The hills of these areas are generally low and gently sloping. Soil ranges from clay loams to pale brown (acidic) clay loams on the hills. The tropical monsoon climate prevails in the area with an average maximum temperature of 30.7 °C and average minimum temperature of 18.9°C. The average annual rainfall is 3931mm, most of which falls be-tween June-September (BBS/UNDP 2005). The forest areas are undulating with slopes and hillocks, locally called tilla. The study forests are semi-deciduous tropical forest type. Methods The present study was carried out from January 2010 to July, 2010. A stratified random quadrate method was used to deter-mine the regeneration status of the tree species of KNP and TGEP of Northeastern region, Bangladesh. Sample plots in the study areas were selected from five different habitats namely; forest, roadside, homestead (surrounding forest dwellers house), fallow land and others (canals, streams and tea gardens side).Total 200 sample plots (100 from KNP and 100 from TGEP) of 2 m×2 m in size. The characteristics of all seedlings/saplings and coppices of both indigenous and exotic species were recorded. Species density, frequency and abundance were calculated by the methods of Shukla and Chandal (2000). The relative density, relative frequency and relative abundance were calculated by the methods of Misra (1968). Importance Value Index (IVI) were calculated by the methods of Shukla and Chandal (2000). The collected species were identified (Prain 1903; Brandis 1906; Heining 1925; Das et al. 2001; Dey 2006). During the present study, eight diversity and richness indices were analyzed to get a clear picture of regeneration diversity tree species in the study areas: SDI=S/N (1) where, SDI is the species diversity index (Odum 1971); S the total number of species; N the total number of individuals of all the species. R= (S-1) / Ln(N)(2) where, R is the species richness index (Margalef 1958); n is the number of individuals of each species. H = -∑ PiLnPi (3) where, H is the Shannon-Winner diversity index (Michael 1990), and Pi is the number of individuals of one species/Total number of individuals in the samples. Hmax=Ln (S) (4) where, Hmax is Shannon’s maximum diversity index (Kent et al. 1992), S is the total number of species. EH=H/Hmax (5) where, EH is Shannon’s equitability index (Kent et al. 1992); H the Shannon-Winner diversity index; Hmax the Shannon’s maxi-mum diversity index. E= H/Log (S) (6) where is E is the species evenness index (Pielou 1966), H the Shannon-Winner diversity index, and S the total number of species. D=∑ Pi2 (7) where, D is the Simpson index (Magurran 1988), Pi is the Number of individuals of one species/Total number of individuals in the samples. As biodiversity increases, the Simpson index de-creases. Therefore, it is worthy to get a clear picture of species dominance. D'=1- D (8) where, D'is dominance of Simpson index.

Source of Information: Journal of Forestry Research (2011) 22(4): 551-559

Article Link (Online Journal): DOI 10.1007/s11676-011-0198-0

Funding Source:

Budget:

Total Budget (Tk.) :

Achievement/Findings:

The findings of present study provide a complete view of regeneration status in the study areas and possess a rich regeneration species composition, status and diversity. Data from five types of habitats proved that they are also profound in their surrounding locations. The present study suggests that disturbances such as extraction of seedling/saplings for fuel wood, grazing, disturbance of seed dispersal, etc. has brought a decline in plant communities. The present study in and around two-biodiversity conservation areas is a small sample for exploring the actual thing for natural regeneration composition, status and diversity. Further study is highly recommended to reexamine the present findings. The study finally concludes that a proper protection from human interferences and scientific management of natural regeneration of the study areas may lead a biodiversity rich site in the country.

Knowledge Management: Journal