An ecological analysis of mangroves ecosystem of odisha on the eastern coast of India

Abstract

The present paper deals with ecological investigation of mangrove ecosystem of Bhitarkanika sanctuary in Odisha. The structural parameters like height, diameter and basal area of mangrove tree species at four sites of the sanctuary viz., Bhitarkanika, Dangmal, Thakurdia and Kakranasi, were measured and compared with the mangroves of other parts of the world. Dominance diversity curve was found lognormal in shape for this area representing high diversity condition. Of the 29 species recorded from the study sites, only 8 specics were common at all sites. The trees with higher DBH classes were found in the protected core sites of Bhitarkanika and Dangmal. Avicennia officinalis and Sonneratia apelala formed the top storey in the river bank regions in Bhitarkanika and Dangmal forest blocks, whereas Sonneratia caeseolaris and Rhizophora mucronata formed top canopy in the river bank areas of Thakurdia and Kakranasi blocks. Exocaria agallocha and Hertiera fames generally have higher basal area and they formed the top storey in the interior forest areas at all sites. Across all sites and species, it was observed that Exocaria agallocha, Avicennia officinalis and Hertiera fames accounted for more than 50% of the total Importance Value Index (IVI) in Bhitarkanika sanctuary. The mangroves of Bhitarkanika have lower heights, low basal area and higher number of plants compared to other mangroves of the world. The Riverine species of Bhitarkanika ecosystem have much higher complexity index values than other mangrove ecosystems of the world, which indicates that this ecosystem is favourable to a diversity of mangrove species.