ABSTRACT
Understanding the relationship between species distribution and environmental conditions is essential to develop climate change–adaptive mitigation and conservation measures. The present study discusses the vegetation distribution in the three biogeographic zones of the Indo-Gangetic region (Terai, the Gangetic plains, and the semi-arid zone) using remotely sensed imagery and canonical correspondence analysis (CCA). Here, we have assessed the species composition and distribution by analyzing satellite data-derived vegetation cover and ground-sampled data. The Terai zone exhibits humid ecosystems, whereas the Gangetic plains and semi-arid zones accommodate the dry xeric ecosystem. High resource exploitation and rapid urbanization in the Indo-Gangetic plains resulted in lower species richness from Terai to the semi-arid zone through the Gangetic plains. The highest ratio for species family was observed in the semi-arid zone 74/38 (51%), followed by the Gangetic plains 114/46 (40%) and Terai 237/72 (30%). CCA showed that precipitation, soil type, and elevation are positively related to the first synthetic gradient, whereas temperature is negatively correlated. The trees demonstrated a positive correlation with precipitation and mean temperature, and an insignificant correlation with elevation and soil type. Overall, the region shows the species distribution pattern regulated by decreasing temperature and increasing precipitation from semi-arid to the Terai zone through the Gangetic plains. Higher species richness was observed in the Terai region, indicating less human interference and more suitable environmental conditions than the Gangetic plain and semi-arid region. The results reveal the dominant contribution of precipitation in regulating species distribution in the three zones. The study demonstrated dominance of species richness and natural forest cover in humid ecosystems of Terai zone, than found in the semi-arid and Gangetic plains. The study suggests that environmental parameters and human interference play crucial roles in determining species distribution patterns and ecosystem structure in the Indo-Gangetic plains.
