Linking biodiversity with the forest patch size of village common forests in Chittagong Hill Tracts, Bangladesh

This study evaluated the relationship of biodiversity with the patch size of village common forests (VCF) by analyzing floral biodiversity based on data from 25 selected VCFs in the Chittagong Hill Tracts (CHT), Bangladesh. The study took 225 quadratic plots by taking nine 10 m × 10 m plots from each VCF—three from each of base, mid, and top hill slopes. The coefficient of similarity (CS) among VCFs and forest community features including species richness, basal area, and popular diversity indices were calculated. Generalized linear model (GLM) assessed the bearings of patch size, slope, and elevation on stand parameters. In all, the study recorded the occurrence of 165 plant species from 52 families. Euphorbiaceae was the dominant family with 18 species. Seven least concerned and four threatened species as per the IUCN red data list of Bangladesh were found in VCFs. Vitex peduncularis had the highest importance value index (IVI) score followed by Lannea coromandelica and Ficus hispida. The mean CS of the VCFs was 0.54. The VCFs were rich in biodiversity, as indicated by observed species richness (644 species/ha), stem density (7111 plants/ha), basal area (65.56 m2/ha). Scores in biodiversity indices, viz. Shannon–Wiener diversity index (2.59), Simpson index (0.90), and evenness index (0.61), also concluded rich but heterogeneous biodiversity among VCFs comparable to other natural forests in the country. The GLM revealed the absence of significant (p ≤ 0.05) bearings of patch size, elevation, or slope on community parameters. The insensitivity of forest community parameters to patch size and elevation indicated the value of conserving VCFs irrespective of sizes and locations.