A local exploratory assessment of mangrove aboveground carbon stocks based on Sentinel-2 NDVI in Pangpang Bay, Indonesia

Mangrove ecosystems play an important role in climate change mitigation through their capacity to store large amounts of blue carbon. Accurate estimation of aboveground biomass (AGB) is therefore essential for monitoring carbon dynamics and supporting sustainable mangrove management. This study evaluated the applicability of Sentinel-2-derived Normalized Difference Vegetation Index (NDVI) for estimating mangrove aboveground biomass and carbon stocks in Pangpang Bay, East Java, Indonesia. Field measurements from 13 sample plots were used to develop an empirical relationship between NDVI and AGB. The resulting regression model (AGB = − 871.15 + 4562.73 × NDVI) showed a significant positive relationship (R² = 0.649, p < 0.001), indicating that NDVI explained approximately 65% of the observed biomass variability. Application of the model to multitemporal Sentinel-2 imagery (2019, 2022, and 2025) revealed substantial spatial and temporal variation in mangrove biomass and carbon stocks. Biomass and carbon declined markedly between 2019 and 2022, corresponding to a 35.1% reduction in mean NDVI, and showed only limited recovery by 2025. Areas dominated by mature Rhizophora and Bruguiera stands consistently exhibited higher biomass and carbon stocks than Sonneratia-dominated stands. These findings suggest that Sentinel-2 NDVI provides a practical and cost-effective approach for monitoring mangrove biomass dynamics and supporting blue carbon assessment, ecosystem restoration, and monitoring, reporting, and verification (MRV) programs in data-limited coastal environments.