Tropical protected and reserved forests are the most active and diversified ecosystem that plays a significant role in maintaining the ecological balance. These forests are experiencing the problem of extensive forest deforestation due to illegal encroachment by the surrounding communities. Assessing forest cover dynamics and its health assessment plays a significant contribution to the management of the forest biodiversity and ecosystem. The present study aims to assess the forest dynamics using multi-temporal satellite data from 1990-2022 (i.e., 10 years intervals of satellite images from Landsat-5 and Landsat-8). The study has been conducted in Behali Reserve Forest (BRF) located in the northeastern Himalayas. Furthermore, we assessed its health conditions based on biophysical and biochemical parameters derived from Sentinel-2A satellite images and near-proximal sensors. The key findings indicate that over the span of 1990-2022, there is considerable forest cover losses of 15% during the 1990s, with a gain of 1.3% during the 2000s and 0.01 % during the 2010s. The net change in forest dynamics showed about 25.2 km2 (17.3%) areas undergone deforestation while 3.7 km2 (2.5%) areas expanded under afforestation in the last three decades (1990-2022).
Health assessment was performed by using LAI and leaf chlorophyll which serves as a key indicator of leaf canopy density and photosynthetic pigment, respectively. The key findings related to health assessment indicate that LAI ranged from 1 to 5.5 and the healthy dense forests showed LAI ≥ 4.5. The Normalized Area Over Reflectance Curve (NAOC) index based leaf chlorophyll content of dense forests showed that chlorophyll ranged between 30 and 45 μg/cm2. The leaf chlorophyll content from satellite and field-based measurements exhibited a coefficient of determinants (R2) of 0.88, indicating strong relationships. We can conclude that this study helps to exemplify the potential of remote sensing techniques to evaluate the dynamics of tropical forests and their biophysical and biochemical properties. It provides critical information about forest dynamics and its health conditions, which are useful for forest conservation and management.
