Review of Researches on Source and Sink of Wetland Ecosystem CO_2

Wetland ecosystem plays an important role in the fixation and release of greenhouse gases,and thus the researches on source and sink of wetland ecosystem CO2 become a hot issue.The characteristics of source and sink of wetland ecosystem CO2 in recent years were summarized,and the effects of natural environment factor and human activity on source and sink of wetland ecosystem CO2 were also discussed.Studies have shown that the majority of wetland ecosystem is a sink of atmospheric CO2 currently,while the net ecosystem exchange of CO2(NEE)changes with significant temporal and spatial characteristics.Temperature is a very important factor which affects NEE.Soil factors including temperature and pH also have obvious effects.Wetland hydrology influences NEE through changing water level.With different vegetation types and its interference,the characteristics of source and sink of wetland ecosystem CO2 is different.Wetland has become a source of atmospheric CO2 under human activities,the function as CO2 sink is restored after the ecological restoration.