Comparative study on structural composition and community association of Nambor Wildlife Sanctuary and its SouthWestward extended Bornewria forest, Assam, India

Knowledge of species composition and diversity are of utmost importance, not only to understand the structure of a forest community but also for planning and implementation of conservation strategy of the community. An extensive field study was undertaken to ascertain the structural composition, species diversity and community association of two forest sites i.e. Nambor Wildlife Sanctuary (NWLS) and its South-Westward extended Bornewria forest of Assam, India. The forests represent Tropical moist semi-evergreen and moist mixed deciduous type. The entire area was embraced with a fragmented block of Gondowana formation. A total of 261 plant species were observed from the two forests sites in floristic assessment. Out of which 247 species were recorded from NWLS and in Bornewria forest 136 were enumerated. The overexploitation and shifting cultivation adversely affected the total forested area and species composition of Bornewria forest. Phytosociological studies showed that Vatica lanceaefolia (15.47) followed by Magnolia hodgsonii (10.97), Castanopsis hystrix (10.02) and Mesua ferrea (9.56) were dominated in NWLS. However, in case of Bornewria forest, Hydnocarpus kurzii expressed its dominance with highest IVI values (15.98), followed by Dysoxylum excelsum (13.52), Mesua ferrea (12.37) and Stereospermum tetragonum (11.87). Plant species diversity was quantitatively higher in NWLS in comparison to Bornewria forest because of ecological destabilization and disturbance in their natural abode. Study on regeneration status of NWLS revealed that 67.42% trees were naturally regenerated. Mesua ferrea and Vatica lanceifolia were the most ecologically successful species with IVI of 7.66 and 5.27 in the seedling stage. In Bornewria forest site 42 regenerating tree individuals were recorded. The maximum quantity of seedlings of Hydnocarpus kurzii was noticed in the forest which showed mass regeneration status of the species. Both the forest desires to curb the anthropogenic disturbance, so that protect the integrity of the forest.