Tree Diversity Pattern in Sub-Humid Tropical Foothill Forest of Indian Eastern Himalayas

A study was conducted at Chilapatta Reserve Forest, West Bengal India to assess its tree diversity and to document its floristic characteristics. Stratified random nested quadrate sampling was adopted for analyzing the quantitative characters. One hundred fifty nine tree species were recorded, of which twenty nine are yet to be identified. Identified species represented 41 families and 91 genera. The tree diversity index, concentration of dominance, Shannon and Wiener index and evenness index estimated was 2.07, 0.018, 4.70 and 1.43, respectively. Highest and lowest frequency recorded was 0.19 and 54.39 while relative frequency varied from 0.01 to 5.15. Tree -1 density ranged from 0.44 to 172.81 individuals ha⁻¹ and relative density ranged from 0.01to 1.96%.Trees were widely distributed and its abundance ranged from 0.60 to 17.83 while relative abundance ranged from 0.07 to 1.89. %. IVI ranged between 0.13 and 8.74. The tree stratum was clearly distinguished in to three layers according to the size of the trees i.e. the height they attained (tall, medium and low heights). The forest can be classified as dense forest having more or less continuous tree canopy with more than 80% interception of incident PAR. Higher IVI value indicates ecological significance of the tree species in the forest. The tree density, dominance and diversity will indicate changes and susceptibility to anthropogenic stressors among various vegetation categories and their formation.