Global patterns and driving factors of the carbon accumulation rate in coastal wetlands

Abstract

Coastal wetlands play crucial roles in sequestering organic carbon, which is vital for mitigating climate change. However, the global patterns and determinants of the organic carbon accumulation rate (CAR) in coastal ecosystems remain highly uncertain. In this study, we evaluate the spatial variability of the CAR across coastal wetlands around the world. In addition, we assess the direct and indirect effects of climatic, edaphic, vegetative, marine, and anthropogenic factors by compiling a global CAR database. The results show that the average global CAR in coastal wetlands is 202.75 ± 252.31 g C m⁻² yr⁻¹, with significant differences between tidal marshes and mangroves (p < 0.05). Soil carbon is the primary direct driving factor of CAR variations globally, whereas climatic and marine factors are the primary indirect driving factors. Climate influences the CAR by affecting the vegetation, soil, and marine conditions. Marine factors, especially salinity, have a negative effect on the CAR, whereas global mean sea level rise has a positive effect. Human activities indirectly influence the CAR by affecting the characteristics vegetation and soil. Our findings highlight that natural forces exert dominant control over carbon accumulation in coastal wetlands, whereas anthropogenic interventions can exert both positive and negative impacts on this process. These results emphasize the effects of interactions among multiple environmental driving factors and human activities on global CAR patterns.