Responses of soil organic carbon to wetland restoration—A global meta-analysis

Wetlands are an important part of the terrestrial carbon pool in the global carbon cycle, and exploring the impact of wetland restoration on soil organic carbon (SOC) is of great significance for implementing effective wetland restoration measures to mitigate global warming. We conducted a global meta-analysis to analyze the response of SOC content to different wetland restoration approaches by comparing restored wetlands with degraded and natural wetlands, respectively. We also aimed to identify their temporal evolution, driving factors and potential mechanisms of wetland restoration. The results of this study showed that natural restoration methods, such as farmland abandonment and grazing prohibition, were effective in increasing wetland SOC. Specifically, the SOC contents of wetlands restored using these methods were significantly higher than those of degraded wetlands. Wetland restoration initially caused SOC to show a rapid growth trend, peaking in years 10-20, before levelling off over a longer period of time. After 40 years of restoration, wetland SOC levels were able to approach those of natural wetlands. Important factors driving wetland SOC restoration include total nitrogen, mean annual temperature, and mean annual precipitation. This study would provide insights for mitigating climate change through wetland SOC restoration.