ABSTRACT
Mangroves contribute to wave attenuation, sediment trapping and wave erosion reduction. A loss of approximately 50% in the worldwide mangrove population is observed since 1990. Anthropogenic activities as well as tidal variations due to climate change are to be blamed along with natural calamities. Thus, proper regular monitoring with policy development from the authorities is a must along with keeping a check on the global climate change propagating activities. This research was conducted to monitor such changes over a period of three decades. For the purpose, multispectral Landsat 5 TM image for the 1990 data and Sentinel 2 image for the 2020 data were used in this multi-decadal study having 30 years span. Biophysical parameters, Leaf Area Index (LAI) and Percentage Canopy Cover (PCC), were studied to analyze the changes in the mangrove forest. Vegetation indices like the normalized difference vegetation index and the modified simple ratio vegetation index were used in the derivation of these parameters. The study shows a mean increment in the LAI during last three decades. This in turn concludes that the individual tree stands have grown to be healthier over the decades. Areal extents for the mangrove positions were taken from the Global Mangrove Watch. A decrease in the areal extent (from 1996 to 2016) was found solely in the Indian portion of the Sundarbans. The spatio-temporal changes in the canopy cover density were also identified. All these change analyses can be helpful to assess overall health status of this important ecosystem over India.
