Immediate disturbances induced by tropical cyclone Fani on the coastal forest landscape of eastern India: A geospatial analysis

Abstract

An extremely severe tropical cyclone Fani made its landfall on 3rd May, 2019 along the coastal region of Odisha, India causing profound damage to its natural and human resources. This study examines the immediate effects of the cyclone on vegetation dynamics and patterns of canopy gap formation in Balukhand Wildlife Sanctuary of this region. Sentinel 2A data of pre and post-Fani scenarios were used to derive Normalized Difference Vegetation Index (NDVI) and relevant landscape metrics of patch and class levels for this forest from coast (zone A) to inland (zone C). Results showed that even the maximum NDVI values of the post-cyclone scenario were either less than or equal to the mean NDVI values of the pre-cyclone scenario for most of the grids of three zones. Among the twenty three grids, severe damage was identified in seven grids mostly covering western parts of the forest owing to high levels of exploitative human interventions. Species like Casuarina equisetifolia and Eucalyptus globulus had suffered the most. The individual as well as combined interactions of land cover and cyclone scenario were found to have significantly strong effects on patch metric values (p < 0.01) in three-way analysis of variance. Regarding canopy gaps, zone A was characterized by clusters of few large patches (> 1 ha area; > 400 m perimeter) and multiple tiny patches but canopies of zone B and C were primarily perforated through multitudes of tiny, irregular cum amorphous gaps. Zone-wise ecological restoration was recommended to mitigate the statistically significant losses of vegetated patches (p < 0.001) due to the cyclone and accordingly relevant species were suggested for site-specific plantation.