Floristic Structure, Diversity and Edaphic Attributes of Mangroves of the Andaman Islands, India

Abstract

The mangroves of Andaman and Nicobar Islands are considered as one of the finest vegetation in India with respect to species composition as well as structure. However scientific information on the influence of edaphic attributes on the structure of Andaman mangroves are lacking. Hence, we assessed the floristic composition, structural attributes, zonation pattern and its relation to edaphic variables of mangroves of the Andaman islands. Quadrat method was employed to estimate the different structural variables and multiple regression analysis to explain the influence of edaphic variables over structural attributes. Floristic analysis of 420 quadrats (10x10m) revealed a mixed species composition with 28 true mangroves in Andamans, of which Avicennia officinalis, Rhizophora apiculata, and R. mucronata were designated as the most important species based on the importance value index. Stem density varied from 133 to 14,000 ha−1 and individual basal area 0.07–78.75 m2 ha−1, further, most of the mangrove habitats showed very high stand basal area. Relatively higher Maturity Index Value was observed indicating high structural maturity in Andamans. Species zonation pattern typically varies based on the tidal inundation. Multiple regression analysis revealed the importance of soil pH, silt, total carbon, total Nitrogen and salinity in shaping the structure of Andaman mangroves. The data evolved in the study would be valuable in the site-specific management and conservation approaches of mangroves in Andamans.