Remote Sensing-Based Assessment of Mangrove Forest Health and Carbon Sequestration Capacity Along the Coasts of the Sundarbans Biosphere Reserve.

Mangrove forests within the Sundarbans Biosphere Reserve provide critical ecosystem services, notably functioning as vital coastal buffers and substantial blue carbon sinks. However, these halophytic communities face accelerating pressures from cyclonic disturbances, sea-level rise, and anthropogenic encroachment. This study presents a multi-temporal remote sensing assessment of mangrove forest health and carbon sequestration capacity across the Indian Sundarbans from 2018 to 2023. Using high-resolution multispectral imagery from Sentinel-2 MSI and Landsat-8/9 OLI, we calculated vegetation vigor metrics—including the Normalized Difference Vegetation Index (NDVI) and Normalized Difference Red Edge Index (NDRE)—and coupled these with ground-truth inventory data to model Aboveground Biomass (AGB) via a tuned Random Forest regression framework (R² = 0.84, RMSE = 18.32 Mg ha⁻¹). The results reveal significant spatial heterogeneity: while pristine interior zones dominated by Heritiera fomes and Bruguiera gymnorhiza exhibited high biomass densities exceeding 220 Mg ha⁻¹ and sequestered up to 7.12 Mg C ha⁻¹ yr⁻¹, peripheral seaward and western zones showed marked degradation and canopy thinning driven by elevated salinity and cyclone impacts. Overall, total aboveground carbon stocks were estimated at 24.18 ± 2.6 Tg C. This investigation demonstrates the efficacy of integrating red-edge spectral indices with machine learning for precise monitoring of blue carbon dynamics, offering quantitative benchmarks for regional conservation and climate mitigation frameworks.