Multitemporal Analysis of Mangrove Aboveground Carbon in the Perancak Estuary, Indonesia Using PlanetScope Imagery from 2020 to 2025

Abstract

Mangroves are among the most effective vegetation types for carbon sequestration, storing carbon absorbed through photosynthesis in stems, leaves, roots, and substrates. Conventional methods for estimating Above Ground Carbon (AGC), such as destructive sampling, can damage mangrove ecosystems and are generally inefficient. Remote sensing offers a more efficient and less invasive alternative, enabling improved monitoring in terms of time, labor, and cost. This study maps and monitors mangrove AGC in the Perancak Estuary, Bali, Indonesia, using PlanetScope imagery. Field-based carbon measurements were conducted using the Diameter at Breast Height (DBH) method, which was converted to biomass using species-specific allometric equations and then to AGC using a conversion factor of 47% of total biomass. Three vegetation indices were evaluated: the Normalized Difference Vegetation Index (NDVI), the Normalized Difference Red Edge Index (NDRE), and the Green Normalized Difference Vegetation Index (GNDVI). Model performance was assessed using the coefficient of determination (R²) and Root Mean Square Error (RMSE). NDRE yielded the best performance, with an R² of 0.341 and an RMSE of 0.039. The estimated AGC at the study site in 2025, derived from PlanetScope imagery using the NDRE index, ranges from 8.04 to 78.60 Mg C ha⁻¹. Multitemporal analysis shows that AGC remains relatively stable over time but increases significantly in 2025, indicating potential mangrove growth and enhanced carbon storage capacity.