Differential carbon stocks and burial rates in natural versus planted mangrove forests under varied hydrogeomorphic conditions

Abstract

Current research on mangrove ecosystems has highlighted their critical role in carbon sequestration, but significant knowledge gaps remain regarding the dynamics of organic carbon burial and its sources under different hydrogeomorphic conditions. This study investigated these dynamics in natural and restored mangrove forests. Our findings revealed that estuarine natural forests exhibited the highest carbon stocks, and greater inputs of local carbon sources compared to other mangrove types (estuarine restored forests, coastal restored forests and coastal natural forests). The turnover rate of organic carbon was found to be highest in estuarine natural forests, indicating relatively lower stability and a greater capacity to sequester more carbon into the soil. Additionally, external carbon sources, particularly phytoplankton, significantly impacted the burial of organic carbon, with higher proportions in coastal environments than in estuarine environments. These findings clearly indicated that hydrogeomorphic conditions played a crucial role in shaping the dynamics of organic carbon sequestration in mangrove ecosystems. Our study emphasized the necessity of incorporating both natural and restored mangrove forests into carbon accounting frameworks to more accurately assess and promote their role in climate change mitigation.