Mangrove Responses to Climate Change along the Southwestern Coast of India during Holocene: Evidence from Palynology and Geochronology

Abstract

Mangrove vegetation is an important component of the coastal ecosystem and is associated with near-shore marine habitat in the tropics and subtropics of the world. Indian mangrove vegetation covers about 6749 km2 along the 7516 km long coast line, including Island territories (Mandal and Naskar, 2008). The distribution of mangrove areas along the Indian coast is influenced by physical forces such as geomorphology, climate, tidal amplitude and duration and quantity of freshwater inflow (Selvam, 2003). In fact, the geomorphic setting of the mangroves of east coast of India is different from that of the west coast (Ahmed, 1972). The coastal strip of west coast is narrow, and steep in slope as compared to the gentle slope of east coast. Though there are large number of small rivers bringing enormous quantity of sediment to the Arabian Sea along the west coast, deltas are not developed, possibly due to the high-energy conditions of the coast. This topographic set up gives a contrasting pattern of mangrove vegetation in India. Accordingly, the mangrove wetlands of west coast are small, less diverse and less complicated in tidal creek network, while the east coast has larger mangrove wetlands with high species diversity. Besides, beach morphological changes along the west coast are controlled by the southwest monsoon. Therefore it is interesting to ascertain the consequences of mangroves in response to climate changes along the Kerala coast, southwestern India using the sedimentary archives of the coastal plains.