Spatio-Temporal Variations in Mangrove Vegetation in conjunction with Related Environmental Factors in Pichavaram (India) 1996-2016

The major objective of the study is to explore the inter-annual vegetation changes of Pichavaram mangroves over two decades (from 1996 to 2016). The study mainly focuses on the summer and onset monsoon season, where the variability in vegetation is easily noticed. Vegetation indices like Normalized Difference Vegetation Index (NDVI), Land Surface Temperature (LST) and Land Surface Water Index (LSWI) were estimated from the remotely sensed data of Landsat imagery. A comprehensive evaluation of the relationship among the vegetation indices reveals that there is an increase in the area occupied by the mangroves throughout the years. Correspondingly, the area under the mangrove cover have also faced an increase in the surface temperature, but much lesser when compared to the adjacent areas. According to the results obtained, NDVI, LSWI, LST, can be used to understand the status of mangrove vegetation with increase and decrease of temperature and water. It is found that the correlation among the remotely sensed indices depend on the season of the year. The summer season in general exhibited higher negative correlation with NDVI and LST and also between LST and LSWI than the onset monsoon season. It is also apparent that with the passing of years, the correlations among the indices are also found to be increasing. Thus in the global scenario of variable climate change, it is important to monitor the seasonal changes in vegetation, especially mangroves, for their effective conservation.