Comparative assessment of biomass, carbon storage and soil CO2 fluxes in degraded mangroves in the major estuarine gradients of the sundarban, India.

Mangroves provide critical ecosystem services, including coastal protection, biodiversity conservation, and carbon sequestration. However, global degradation reduces their carbon sequestration capacity and increases carbon dioxide (CO2) emissions. Therefore, to quantify the biomass, carbon storage potential of mangrove species, soil CO2 fluxes, and total carbon stock in the degraded mangrove systems of Sundarban, India, nine different sites were selected based on degradation status and estuarine types. Sites were categorized based on proximity to human habitation: very close (<500 m), close (500-1.5 km), and far (>1.5 km). These sites were distributed across the three major estuarine systems: Matla, Bidyadhari, and Hooghly. The above ground and root biomass of different mangrove species were estimated by using allometric equations. The carbon contents of above and below ground parts were quantified to determine the carbon storage potential of the degraded mangrove systems. The CO2 fluxes were measured using the closed chamber method. The total carbon storage potential varied in the range of 67.38 ± 1.87 (Hooghly Estuary) to 82.57 ± 2.87 Mg C ha-1 (Matla Estuary) with an average of 73.04 ± 2.31 Mg C ha-1. In the studied sites, the highest CO2 flux (117.59 ± 2.59 mg m-2 h-1) was recorded at the highly degraded sites nearer to human habitat. Degraded mangroves sites at Hooghly and Bidyadhari estuarine showed low C-storage potential due to higher anthropogenic activities, poor mangroves specified diversities and proximity to the sea. So, those regions demand greater intervention to protect the mangrove ecosystems in Sundarban, India.