Effect of different factors dominated by water level environment on wetland carbon emissions.

Abstract

The exacerbation of global warming has led to changes in wetland carbon emissions worldwide. Therefore, we conducted a meta-analysis of methane (CH4) and carbon dioxide (CO2) emissions in wetland ecosystem and explored the underlying mechanisms. Our finding indicated that (1) water level of -50 to 30cm (the negative value represents the depth of the groundwater table, whereas the positive value represents the height of the above-ground water table) and -10cm will result in a large CH4 and CO2 emissions, respectively;(2) CO2 and CH4 massive emissions occurred at the temperature range of 15-20°C and > 20°C, respectively;(3) CH4 and CO2 emissions were higher when the mean annual precipitation (MAP) was between 400 and 800mm, but lower at an range of 800-1200mm; (4) there was no significant difference in CH4 and CO2 emissions in marshover time; however, CO2 emissions in fenwere relatively high; (5) there was no significant difference in CO2 emissions between the forest, grass, and shrub groups; there was also no significant difference in CH4 emission within the forest group;and(6) MAP has a low impact (0.577) on the CO2 emissions of wetlands. Collectively, our findings highlight the characteristics of wetland CH4 and CO2 emissions under different conditions dominated by water level, enhance our understanding of the potential mechanisms that govern these effects, and provide basis for future wetland management and restoration in the future.