Mangroves of India: History and palynostratigraphy of Chilka Lake, Orissa

Abstract

Fine resolution palynostratigraphy centred on Chilka Lake is aimed at the reconstruction of history of mangrove vegetation in tidal flat, salt marsh and fresh water wetland environments. Pollen analyses of air catches, lake water, lake bottom mud and surface soil samples have been collectively used to quantify the dispersal and preservation of pollen in relation to the modern vegetation. Pollen analysis of a 5.50 m deep profile from Balugaon at the western flank of the lake in prograded delta zone has been done which provides information about the changes in vegetation and depositional environments from approximately 3,100 radiocarbon years B.P. to the present. The results obtained suggest that (i) air catches are devoid of mangrove taxa instead seasonal non-arboreals and planted trees dominate, (ii) lake water, surface sediments and lake bottom mud samples have recorded the occurrence of both core mangroves and mangrove associates to the extent of 10-33 and 50-83 per cent, respectively, and (iii) Balugaon profile portrays the existence of marine, brackish and fresh water bioassemblages. On the basis of subtle changes in the vegetation, various depositional environments, transgressive and regressive facies have been determined.