Plant diversity patterns along environmental gradients in Nanda Devi Biosphere Reserve, West Himalaya

Mid to high-altitude vegetation in part of west Himalaya, India has been investigated and analyzed for assessing species distribution in relation to environmental variables. The buffer zone site of Nanda Devi Biosphere Reserve (NDBR) in Pindari–Sunderdhunga–Kafni (PSK) area (30 forest stands in 11 forest communities) of Kumaun and Lata–Tolma–Phagti (LTP) area (30 forest stands in 8 forest communities) of Garhwal region having 11 forest communities along different elevation gradients was identified for detailed surveys. Species composition showed a total of 451, distributed in NDBR along Pindari–Sunderdhunga–Kafni site and Lata–Tolma–Phagti transects. Among communities, Quercus semecarpifolia and Mixed Abies pindrow-Quercus spp. communities in Pindari–Sunderdhunga–Kafni site with 23 species each and Pinus wallichiana community in Lata–Tolma–Phagti site with 18 species showed highest species composition. The interrelationship between environmental variables and species distribution was analysed using Simple Linear Correlation analysis and Canonical Correspondence Analysis (CCA). Simple Linear Correlation and CCA indicated compositional differences in forest types that perhaps was caused by differences in species richness and forest composition. In both the sites, among all the environmental variables, elevation, slope and organic carbon were found to be the most controlling factor for species distribution. Different forest structural components like species richness, total basal area, canopy density was found to be varying greatly with environmental factors and human disturbance, however, more datasets of vegetation dynamics and responses are required to further strengthen this premise.