Distribution and plant diversity of mangroves in the west coast of Kerala, India

Abstract

Mangroves in India account for about 5 per cent of the world’s mangrove vegetation and are spread over an area of about 4,500 km² along the coastal States/UTs of the country. Various studies showed that mangrove vegetation cover only 1,095 ha in Kerala (Kurien, et al., 1994). According to another estimate, Kerala once supported about 700 km² mangroves and what we see now are only relics of a great past (Ramachandran et al., 1985). It can be noted that out of the total 1671 ha of mangroves in Kerala, 1470 ha are with private holders (Basha, 1991). The present investigation was carried out in the mangrove areas of Kerala to document the extent of mangroves, various attributes of plant diversity, causes of degradation and regeneration etc. during 2010- 2012 by involving experts, activists, scientists etc. under the leadership of Kerala Sasthrasahithya Parishath, an NGO working in Kerala. Data collection was based on frequent visit to mangroves areas and gathering information from the local activists, scientists and local self government officials. According to the estimate of this study, the extent of mangroves of Kerala is 2502 ha out of which 1189 ha belongs to the state but 1313 ha is under private ownership. The mangrove flora is unique in nature due to its restricted distribution only to the tidal zones. A total of 15 pure mangroves species and about 33 semi mangrove species were recorded in the study. It is also observed that except few areas, most of the mangroves in Kerala are in an irreversible process of degradation. The Mangroves had been degraded due to construction of a number of barrages for irrigation purposes, clear felling and lack of fresh water supply, lack of tidal flushing of the degraded areas, release of pollutants from various domestic and industrial sources, changes in water quality, Illegal sand mining etc. Natural regeneration in underutilized lands in backwater systems, afforestation programmes, conservation initiatives and growing awareness on the mangrove ecosystems have highlighted the need to conserve and manage them sustainably.