Ecosystem carbon storage affected by intertidal locations and climatic factors in three estuarine mangrove forests of South China

Abstract

Recent studies have highlighted that mangroves could serve as an important carbon reservoir, playing an important role in climate regulation. Nonetheless, there remain uncertainties about their carbon storage estimations due to mangrove carbon-cycle processes affected by the interactions among climatic factors, hydro-geomorphic settings, and mangrove species. This study aimed to quantify how ecosystem carbon storage (ECS) (i.e., vegetation biomass and soil organic carbon (SOC)) was affected by intertidal locations and climatic factors based on new and published data from different latitudinal zones. Landward mangrove communities accumulated significantly higher carbon in both vegetation and soil compared with seaward mangrove communities. Average ECS of Dongzhai Harbor, Yingluo Bay, and Dongjiang Estuary were 351.35 Mg ha−1, 306.93 Mg ha−1, and 162.04 Mg ha−1, respectively. ECS values were underestimated because SOC storage accounting for more than 60% of ECS was only estimated on the top 100-cm sediment in this study. Compared with upland forests, there was remarkably higher SOC storage in mangroves, especially in Dongzhai Harbor and Yingluo Bay. Regression analysis indicated that ECS nonlinearly decreased as latitude increased. ECS significantly enhanced as air temperature of the coldest month (Tmin) and mean annual precipitation (Pmean) increased on a global scale, suggesting that Tmin and Pmean were the major controls of ECS. Nevertheless, ECS of mangroves in China was significantly correlated with mean annual air temperature (Tmean) and Tmin at a filed scale, and was nonlinearly increased as Tmin and Tmean increased. Therefore, the influencing factor of ECS spatial patterns was partly affected by statistical scales.