Species-wise Assessment of Above-Ground Biomass and Carbon Sequestration Potential in the Mangroves of Maharashtra, India

Abstract. Mangroves are highly productive ecosystems and are considered the largest potential sinks of atmospheric carbon. However, variability among species and communities significantly influences total carbon stock. This study evaluates the species-wise above-ground biomass (AGB) and carbon stock potential of mangrove species in Maharashtra, India, using primary field data from 44 geotagged plots. The available biomass equations were used to estimate the AGB and carbon at the plot level. Total carbon content was determined by multiplying per hectare AGB with the mangrove area for the 2018–19. Comparative assessment was carried out for the biomass and carbon between different mangrove species, class (dense and open) in the northern (Palghar, Thane, Mumbai, Raigarh districts) and southern zones of Maharashtra (Ratnagiri and Sindhudurg districts).

Out of 18 recorded species, Avicennia marina contributes the highest carbon stock per hectare (particularly in the dense plots of the northern zones) of more than 1500 t/ha, followed by A. officinalis and Sonneratia apetala. The lowest biomass was observed in Sonneratia alba (within open plots in the southern region) with values falling below 100 t/ha. The top 8 carbon-storing species together accounted for more than 90% of total estimated carbon.

Species contribution of the different mangrove species to the average carbon stock in the northern zone was in the order of. Avicennia marina > Avicennia officinalis > Sonneratia apetala, and in the southern zone it was broadly Avicennia officinalis > Lumnitzera racemosa > Excoecaria agallocha.

The biomass recorded was specific for each mangrove species, which may be attributed to adaptabilities of these species to environmental variables. The accumulation of biomass is primarily influenced by species, wood density, age of tree, climate, management regime, proximity to water channel, and nutrient sediment that supplement mangrove productivity (Kairo et al., 2008; Fatoyinbo et al., 2008).

This study confirms significant inter-species variability in carbon sequestration potential among mangrove species in Maharashtra. Species such as Avicennia marina and A. officinalis should be prioritized in restoration projects for maximizing carbon benefits.