Blue Carbon Potential of the old Caaluan Mangrove Conservation Area, Tinambac: Biomass and Carbon Stock Assessment

Abstract

Mangrove forests are recognized as important blue carbon ecosystems because of their capacity to sequester and store substantial amounts of atmospheric carbon. This study assessed the biomass and carbon stock potential of the Old Caaluan Mangrove Conservation Area in Tinambac, Camarines Sur, Philippines. Specifically, biomass and carbon stocks were estimated in three Rhizophora stylosa plantation stands aged 7, 10, and 15 years using stratified quadrat sampling and standardized allometric equations. Measurements of diameter at breast height, tree height, and stand density were used to determine aboveground biomass and corresponding carbon stocks. Results revealed that the 15-year-old plantation stand exhibited the highest biomass (54.50 t ha−1) and carbon stock (24.53 t C ha−1), associated with larger mean diameter at breast height (8.32 cm) and tree heights ranging from 12 to 13 m. The 7-year-old stand recorded higher biomass and carbon stock values than the 10-year-old stand despite its younger age, primarily because of its greater stem density. These findings indicate that plantation age, stand density, and stand structure are important determinants of carbon accumulation and storage in mangrove ecosystems. The results demonstrate the substantial blue carbon potential of the Old Caaluan Mangrove Conservation Area and underscore its ecological importance for climate change mitigation, coastal protection, biodiversity conservation, and community resilience. The study provides baseline information that can support local carbon accounting, mangrove management, and conservation planning. Furthermore, the findings establish a foundation for long-term monitoring and future assessments that incorporate belowground biomass, soil carbon, and sediment carbon pools to improve estimates of total ecosystem carbon storage.