Cost–benefit analysis of ‘Blue Carbon’ sequestration by plantation of few key mangrove species at Sundarban Biosphere Reserve, India

Climate change and global warming have a destabilizing effect on the global environment, and governmental statutory bodies are emphasizing a reduction of emission coupled with restoration of degraded forest lands as a carbon sequestration–emission reduction (REDD+) initiative. Asphyxiated mangrove soil, existing on the borderline of land and sea, has the highest potential to trap ‘blue carbon’; hence, plantation programs have been initiated around the tropical coasts to restore this unique habitat. This case study provides a cost–benefit and carbon sequestration analysis for planting of five mangrove species (Avicennia marina, Bruguiera sexangula, Ceriops tagal, Rhizophora mucronata and Xylocarpus moluccensis) by various methods in a 102.4-ha area at the Indian Sundarbans. It is estimated that as per the planting methods used in the current study and physio-chemical properties of the sediment, coupled with other local factors such as anthropogenic interventions, Avicennia marina planting by the ‘propagule dibbling’ method is the most cost effective (0.002 Euro/survived plant), with the highest increment (97%) in organic carbon density (OCD), humic acid (100.86%) and fulvic acid (48.78%) over a period of 5 years. Survival rate was highest (82%) for Avicennia marina, planted by the ‘transplanting of nursery-grown seedlings’ method. The drain and trench method resulted in a 55% survival rate for Rhizophora mucronata, but the extra labor investment made this the costliest method (0.13 Euro/survived plant) and also less carbon effective (only 85% increment of OCD in 5 years). Planting methods, sediment quality, tidal inundation and salinity variations can play a major role in blue carbon burial/sequestration in mangrove lands.