IMPACT OF LANDUSE CHANGES ON PLANT SPECIES DIVERSITY OF NOKREK BIOSPHERE RESERVE, MEGHALAYA, INDIA

摘要

The impact of land use changes driven by various anthropogenic disturbances on the taxonomic diversity of Nokrek Biosphere Reserve (NBR) in north-east India has been studied. Twelve ecosystems representing natural, semi-natural, man-managed and man-damaged ecosystems were identified. In total, 710 vascular plant species belonging to 465 genera and 140 families were recorded from these communities. The flora of the NBR exhibits saturation of eastern Asiatic elements. Although the elements from 11 biogeographical regions of the world were found in the flora of the undisturbed ecosystems of the NBR, Indo-Malayan, Himalayan and Indo-Burman elements dominated the flora constituting about 86% of the total species content. Ninety-nine threatened categoriesof species, including 43 endemics, were recorded from the NBR. The presence of a large number of rare taxa with small populations and habitat-specificity indicates the vulnerability of threatened category of species.The taxonomic diversity of the secondary forest communities on mining areas and other man-made ecosystems has been drastically reduced. The pace of recovery in species diversity in the communities on the jhum fields was slow, as only 67% of the total species content could recover after 12 years of vegetation development.