Community structure and regeneration status of tree species in Eastern Himalaya: A case study from Neora Valley National Park, West Bengal, India

The phytosociological attributes of temperate forests were investigated in the Upper Range, Neora Valley National Park (NVNP), Eastern Himalaya. The area was grouped into three altitudinal zones viz., lower, middle and upper temperate and tree species were sampled at three life stages (seedlings, saplings and mature trees). The average species richness of trees, saplings and seedlings per forest stands was 15.67 ± 4.04, 14.0 ± 3.61 and 14.67 ± 1.53 respectively which reflects a medium diversity status. The mean density of seedlings (32278.6 ± 3713.13 ha^(-1)) ＞ saplings (840 ± 141.07 ha^(-1)) ＞ trees (248.5 ± 22.79 ha^(-1)). Basal area ranged from 9.36 m^2 ha^(-1) to 29.95 m^2 ha^(-1) for trees, from 1.34 m^2 ha^(-1) to 2.07 m^2 ha^(-1) saplings and from 1.92 m^2 ha^(-1) to 5.75 m^2 ha^(-1) for seedlings at different study sites. It was observed that majority of the tree species at all life stage showed contiguous distribution pattern. Good regeneration status was recorded for maximum species at all the sites. Density-diameter distribution exhibited decrease in tree densities towards higher DBH classes. The present study has provided a baseline data for the long term monitoring of tree communities in the area that will help to assess the effect of present ecological consequences of ongoing and future climate changes.