Mapping Mangrove Foliar Photosynthesis from Space: High-Resolution Estimation of Carbon Sequestration in the Sundarbans Mangrove Forest, Bangladesh

Mangrove forests provide essential climate regulation and coastal protection, yet fine‐scale quantification of carbon dynamics remains limited in the Sundarbans due to spatial heterogeneity and tidal influences. This study estimated canopy structural and photosynthetic dynamics from 2019 to 2023 by integrating high-resolution remote sensing with a light use efficiency modeling framework. Leaf Area Index (LAI) was retrieved at 10 m resolution using the PROSAIL radiative transfer model applied to Sentinel-2 data. Gross Primary Productivity (GPP) was estimated using Sentinel-2 vegetation indices and MODIS fPAR with temperature and water availability constraints. Solar-induced chlorophyll fluorescence (SIF) was derived at 10 m resolution and compared with TROPOMI observations to assess correspondence with photosynthetic activity. LAI and GPP exhibited pronounced seasonal and interannual variability, with higher values during the monsoon growing season and lower values during dry periods. Mean NDVI declined from 2019 to 2023 and modeled annual carbon uptake ranged from approximately 43 to 65 Mt CO₂ eq, with lower sequestration in 2022–2023 associated with climatic stress. Strong correlations among LAI, NDVI, GPP, and SIF indicated consistent coupling of canopy structure and function. These results provide a fine-scale assessment of mangrove carbon dynamics relevant for conservation and climate mitigation planning.