Tree Species Composition, Diversity, and Regeneration Patterns in Undisturbed and Disturbed Forests of Barak Valley, South Assam, India

Abstract

Database on occurrence and distribution of floral species provides useful information for prioritizing sites in terms of biodiversity values and management. The effect of human disturbances on species diversity is an issue that has engaged the attention of ecologist for last several decades both from theoretical and applied standpoints. Present study was conducted to examine effect of human disturbance in forest species composition, diversity and regeneration in four tropical forests in Barak Valley, Assam. A total of 137 species were recorded in this study. Cynometra polyandra was dominant species in both the undisturbed forests (IVI values 20.1 and 27.8, respectively in Innerline undisturbed reserve forest (IRUF) and Barak undisturbed reserve forest (BRUF). In Inner line disturbed reserve forest (IRDF) Tetrameles nudiflora (IVI 36.8) and Barak disturbed reserve forest (BRDF) Artocarpus chama (IVI 19.9) were dominant the species. The results revealed that in undisturbed forest, 42-46% of the quadrats had less than 5 species while in the disturbed forest stand it is seen than 72 to 86% plots had less than 5 species. The Shannon Weaver diversity index (H) was higher in undisturbed forests (1.69 and 1.77, respectively in IRUF and BRUF) compared to disturbed forests (1.46 in IRDF and 1.52 in BRDF). The basal area and tree density in undisturbed forest stands found higher than that of disturbed forest stand. Majority of the species (91.84% to 95.65%) were contagiously distributed in all four forest stand. All the forests of the present study showed reversed J-shaped density distribution curves. 31-45% of total species were recorded in sapling stage. The density and basal area of saplings were higher in undisturbed forests than that of disturbed forests. Dominance distribution curves for all the sites fit the geometric series which confirms to the niche preemption hypothesis.