Global controls on carbon storage in mangrove soils

Global-scale variation in mangrove ecosystem properties has been explained using a conceptual framework linking geomorphological processes to distinct coastal environmental settings (CES) for nearly 50 years. However, these assumptions have not been empirically tested at the global scale. Here, we show that CES account for global variability in mangrove soil C:N:P stoichiometry and soil organic carbon (SOC) stocks. Using this ecogeomorphology framework, we developed a global model that captures variation in mangrove SOC stocks compatible with distinct CES. We show that mangrove SOC stocks have been underestimated by up to 50% (a difference of roughly 200 Mg ha −1 ) in carbonate settings and overestimated by up to 86% (around 400 Mg ha −1 ) in deltaic coastlines. Moreover, we provide information for 57 nations that currently lack SOC data, enabling these and other countries to develop or evaluate their blue carbon inventories. A global model that incorporates information about coastal environmental settings indicates that mangrove soil organic carbon stocks have been significantly underestimated in carbonate settings, and overestimated in deltaic coastlines.