Spatial prediction of plant species richness and density in high-altitude forests of Indian west Himalaya

Abstract

Abstract The spatial distributions of plant species are results of variable environmental gradients, including climatic and edaphic factors, biotic factors, different eco-physiological processes, species-specific characteristics, and resource requirements, thus producing spatial heterogeneity. The species distribution and their rate of change across elevational gradients in nineteen forest communities were studied using the quadrat method and statistical modeling tools. Pindari-Sunderdhunga-Kafni (PSK) area of the Kumaun region and the Lata-Tolma-Phagti (LTP) area in the Garhwal region in the buffer zone of Nanda Devi Biosphere Reserve were selected as the extensive study sites. A total of 4278 individual trees belonging to 42 families in the PSK site and 6436 individual trees belonging to 25 families in the LTP site were recorded across elevational gradients between 2050 to 3800 m a.s.l. Because of the narrow elevational range and complexity in the field-based data structure, Generalized Additive Model (GAM) was used to predict the rate of change of species richness and species density. The results showed a significant decrease in density at a rate of 319–355 ind ha-1 per 100 m elevation in the Pindari-Sunderdhunga-Kafni site (P