Floristic Composition and Change in Species Diversity over Long Temporal Scales in Upper Bhotekoshi Hydropower Project Area in Nepal

摘要

Forest and vegetation of particular ecosystem is generally influenced by external factors especially from development activities. Nepal has been endowed with an immense variety of forest resources with its unique biodiversity. The current study is conducted in the temperate forest of central Nepal to compare the state of vegetation recorded during 1995 with the present condition. To identify floristic composition, species distribution and diversity, same location and same size of quadrates were selected in natural forest and planted or regenerated area as in previous study. Measurement and analytical tools for forest and vegetation reveled a total of 19 species and 341 individuals in 0.14 ha regenerated area and 18 species, 17 genera and 260 individuals in 0.16 ha, natural forest areas. However, in 1995, total 31 individuals of 20 woody species, 18 genera and 15 families were recorded within the sampling plots of 0.16 ha of natural forest. Moreover, Alnus nepalensis is found dominating regenerated area and Caryopteris odorata in natural forests whereas in 1995, Litsea chartacea and Maesa chisia were recorded dominant. The Shannon’s diversity H’ = 2.908, E = 0.970 and Var H’ = -0.00 and Simpsons D = 0.027 recorded in 1995 is found to be with higher values when compared with the analysis of present study. Furthermore, in comparison to 1995 study, this study showed lower basal area and timber volume with declining species diversity. Although, the natural forest is found with higher species composition compared to rehabilitated forest, species of herbs and shrubs were found extensively growing.