Analyzing environmental determinants of tree species distributions and regeneration pattern in Western Himalaya, India
Abstract Proper documentation of tree distribution across the globe has been considered crucial to assess the relationships between species occurrence and changing climate, and accordingly in designing the conservation action plans. Himalaya is one of the regions in the world where the temperature is gradually increasing at a rate higher than the global average. Therefore, it becomes imperative to understand the most influential parameters for major tree species distribution and its regeneration pattern across their habitat in Western Himalaya (WH) via direct gradient analysis. We used National Forest Inventory (NFI) data which has a robust statistical design with data collected in a consistent manner across the timeline in systematic order. This allowed us carrying out detail analysis to reveal the aforesaid relationship and pattern. Three topographical factors (altitude, aspect, slope), four major climatic variables (temperature, temperature seasonality, precipitation and its seasonality) and four edaphic factors (soil depth, soil humus, soil consistency and soil coarse fragments) were considered as defining variables. The results indicated that the altitude and temperature were the most determinant factors followed by precipitation in shaping the distribution of major tree species in WH. The analysis also indicated the upward shift of regenerating individuals of these tree species towards higher altitude. These relevant information about the extent of current tree distribution and their regeneration pattern over the last one and half decade might help in systematic conservation planning and monitoring range dynamics under future climate change conditions.