Mangrove blue carbon stocks estimation in South Sulawesi Indonesia

Mangroves are the major sink of blue carbon in coastal ecosystems. However, due to high levels of anthropogenic activities, mangroves rapidly disappear worldwide, resulting in a significant loss of carbon stocks. This study aims to quantify the biomass carbon stock of mangroves (standing live trees and roots) and soil organic carbon stocks at six sample sites affected by aquaculture pond expansions in the Barru District, South Sulawesi Province. We investigated the structure and composition of mangrove vegetation at each site in a 20 m × 50 m transect and sampled six soil cores at depths of 0 cm–15 cm, 15 cm–30 cm, 30 cm–50 cm, and 50 cm–100 cm. We used allometric equations for specific species from previous studies to estimate biomass carbon stocks and used the Loss on Ignition method for soil analysis. Based on the carbon stocks value, the mean values of aboveground (tree) and belowground (root) carbon of mangroves were 100.66 ± 23.44 Mg C ha^-1 and 2.81 ± 1.16 Mg C ha^-1, respectively, while the mean value of soil organic carbon was 570.76 ± 97.70 Mg C ha^-1. The over-exploitation of mangrove areas in this region in the last two decades (for various purposes, but mainly related to aquaculture pond development) has resulted in lower blue carbon estimates than in other regions in Indonesia. Therefore, protecting intact mangrove areas and rehabilitating and restoring areas that have been degraded or lost is essential to conserve blue carbon and rebuild and increase carbon stocks to mitigate climate change and ensure mangrove sustainability.