Influence of edaphic factors on distribution and condition of Himalayan silver birch (Betula utilis D. Don) communities in the northwestern Indian Himalayas

The basic concept of phytosociology is crucial for the assessment of species composition and dynamic ecological succession of forests supporting ecological services, functions, disturbance, and resilience that lead to the development of integrated areas such as ecological niche modeling and contribute to identifying the valuable bio-indicators which can be used in framing conservation and management planning. B. utilis is one of the most dominant tree species of treeline ecotone in the Himalayan Region. The species is also considered as indicator species for monitoring the past and recent climate change impact. The current study was carried out in the natural populations of B. utilis from the sub-alpine zone of North-western Indian Himalaya. The birch dominated forest harbors a total of 305 plant species comprising Angiosperms (51 families, 160 genera and 277 species), Gymnosperms (03 families, 05 genera and 07 species) and Pteridophytes (07 families, 11 genera and 21 species) with Asteraceae, Ranunculaceae and Rosaceae as dominant family. Birch forests are found dominant in shady moist habitat and North West aspect. Geographical characteristics, anthropogenic and developmental activities affect the population structure of B. utilis and associated species. However, the species has fair regeneration status in the study area. The acidic nature of soil pH and spatial variation in edaphic characteristics may be due to geographical differences, rooting patterns and litter accumulation of below and above-ground vegetation. Biomass estimation of a representative population of B. utilis from each site showed that TAGBD, TCD and TBD were found maximum in ST3 (Hamta Pass II site). The CCA analysis determined that environmental variables such as altitude, organic matter, available phosphorous, organic carbon, available nitrogen, and electrical conductivity played a significant role in determining tree species composition and distribution in B. utilis dominated forests.