The Variability of Sedimentary Carbon Stock in Seagrass Ecosystem in Central Tapanuli, Indonesia

Blue carbon is a term to underline coastal ecosystem such as mangrove, seagrass, and tidal marshes capability as carbon sequestration where the organic carbon that stored in coastal sediment is greater than the organic carbon in living biomass. This study analysed the variability of sediment carbon stock in seagrass ecosystem in Central Tapanuli, Indonesia. LOI method was used to determine the carbon stock. Regression analysis showed that depth, and dry bulk density strongly influence the sedimen carbon stock in seagrass ecosystem (R² = 0.77 in Hajoran and R² = 0.79 in Jago-jago) where the total organic carbon stock in upper layer and denser sediment was higher than the organic carbon stock in middle/bottom layer sediment. Moreover, sediment type also influenced the carbon stock where sediment with finer grain size (11.80 – 13.46 Mg C/ha) captured more organic carbon than sand (6.54 – 10.34 Mg C/ha). By knowing this capacity, monitoring and maintaining coastal sediment and vegetation should become priority to mitigate the climate change.