Soil organic carbon changes following wetland cultivation: A global meta-analysis

Wetland cultivation has a profound effect on soil organic carbon (SOC) and global soil carbon cycles. However, the global patterns of the changes in SOC following wetland cultivation are still not well understood, especially with respect to the conditions under which SOC can increase in cultivated wetlands. We synthesized the results from 64 study sites and carried out a meta-analysis to quantify the changes in SOC following wetland cultivation and identify the underlying mechanisms. Although wetland cultivation led to a reduction in SOC under most conditions, wetland cultivation may result in an increase (p < .05) in SOC under the following conditions: the original wetland was a tidal or salt wetland, and the initial SOC content was <30 g/kg. We also observed close correlations between SOC and total nitrogen, soil pH, and bulk density throughout the wetland cultivation process. These results indicate that it is possible to increase SOC following wetland cultivation. The changes in SOC after cultivation depended on wetland cultivation age, cultivation type, type of natural wetland hydrology or hydrology change type, and the initial SOC content. More generally, during the management of wetlands, the original SOC content before wetland cultivation and the balance of SOC inputs and outputs throughout the wetland cultivation process are important aspects that should be considered.