Influence of topographic factors on community parameters in tropical deciduous forests of Eastern India

The present research aimed to determine the NDVI-tree density relationship and the influence of topographic factors (slope, aspect, and altitude) on species richness (SR), species diversity (Hʹ), and tree density in the Sal forests of Ranchi. Random field sampling was performed using 92 belt transects (each of 0.5 ha size) to determine the community parameters, while spatial–temporal high-resolution Sentinel 2A satellite imagery was used for NDVI analysis, and the Advanced Land Observing Satellite, Phased Array Type L-band Synthetic Aperture Radar and Digital elevation model was used to deduce the topographical variability of the studied forests. The pre-monsoon (April 2016 and 2018) and post-monsoon (November 2016 and 2018). The NDVI method gives superior results for vegetation varying in densities and also for scattered vegetation from a multitemporal remote sensing image. A significant positive correlation between tree density and NDVI had been observed in April 2016 (r = 0.94, p < 0.001) and 2018 (r = 0.92, p < 0.001), in November 2016 (r = 0.89, p < 0.001) and 2018 (r = 0.94, p < 0.001) The highest SR range (3–27) was observed in SW and W aspects followed by N (3–25), NE (3–23), E (5–22), and NW (3–22) aspects. The highest Hʹ (2.76) and SR (23) were recorded in transect JH029 at the NE aspect, where tree density was quite poor (only 280 ind. ha −1 ). The density (ind. ha −1 ) of Shorea robusta ranged from 92 to 1616 in the studied Sal forests where a significant positive correlation between NDVI and tree density was observed depicting healthy forest conditions. The findings of this study may be helpful for forest managers and policymakers to identify areas where forest conservation efforts are needed, or to assess the effectiveness of existing policies (The National Forest Policy of India, 1988, National Afforestation Programme, and the Forest Rights Act, 2006) designed to promote sustainable forest management.