Stand Structure and Species Composition in Three Mangrove Forests of Kerala, India

Stand structure and species composition of three ecologically important mangrove forests in Kunhimangalam (the least disturbed and the largest), Mangalavanam (a bird sanctuary with intense anthropogenic activities), and Puthuvypu (an emerging forest) in Kerala state of India were studied. Together they occupied an area of 5.78 km2 and supported 12 true mangrove species. This comes to 80% of the entire true mangrove species occurring in Kerala and 26% reported from India. Avicennia officinalis was the dominant in all the three mangrove forests studied. Kunhimangalam showed more species diversity with ten true mangrove species, followed by Puthuvypu. Kunhimangalam mangrove forests were found to be structurally older with the oldest stock of A. officinalis in Kerala. No distinct zonation was observed in these mangrove forests as their coastal area is very narrow. Low salinity of soil due to the constant influx of freshwater from nearby rivers helps to support commendable species diversity and complex stand structure in the mangroves studied. So, seedling competition and herbivory could be the factors determining the species distribution in these forests.