Himalayas provide high altitudinal gradients and extreme slopes which may lead to rapid changes in climatic zones over a small distance and that reflected in the noticeable changes in the composition of forest communities. We identified and analyzed various forest communities for their woody species dominance, basal cover, regeneration pattern, and ecological indices with effect of climatic variables and altitudes in the Singalila National Park, Khangchendzonga Landscape, Eastern Himalayas (India). We encountered 2075 woody individuals belonging to 70 species in the whole transect along 2000 m to 3636 m asl. The species richness and estimators (Jackknife1 and Chao2) showed a strong negative correlation with the altitude. The entire forest regime reflected a dominance of young trees as per DBH analysis. Actual evapotranspiration, potential evapotranspiration, and moisture index are the measures of available environmental energies which drives the final shape of community composition and structure of the forest. The study revealed that these forces showed a significant positive correlation with the species richness and a negative correlation with the altitudinal gradient. Our study helps to weigh up the effect of geometric constrains and environmental factors in giving shape to the present structure of forest community composition in the Singalila National Park.
