Floristic diversity and distribution of biomass carbon: A preliminary study of mangroves in Chilaw lagoon, Sri Lanka

Mangrove ecosystems across the island face many threats to their survival despite the multitude of benefits provided by them. Their superior carbon sequestration and storage capacity make them ideal for climate change mitigation. However, the conservation and management of these ecosystems are difficult mainly due to the lack of baseline information. The present study is a preliminary investigation of the diversity of mangroves and the distribution of biomass carbon across mangrove species in the Chilaw lagoon in the western coast of Sri Lanka. The study identified 12 species of mangroves belonging to six families in the Chilaw lagoon complex. Shannon’s diversity index (1.90) and evenness (0.76) indicates a relatively higher diversity compared to other lagoon complexes in the island. The most abundant species identified was Bruguiera cylindrica followed by Avicennia marina and A. officinalis. Xylocarpus granatum and B. sexangula were the least abundant species identified. Biomass carbon was calculated from 357 plant stems. The above- and below-ground biomass carbon were 12.80 and 2.6 Mg C, respectively, and thus total biomass carbon content of the Chilaw lagoon was estimated to be 102.8 Mg C ha^-1. The highest contribution to biomass carbon was from B. cylindrica. A. marina too contributed significantly to the biomass carbon, despite fewer individuals encountered.