Abstract: Dissolved organic carbon (DOC) in freshwater is an important component of the global carbon cycle, and is also carbon and energy source for heterotrophs in freshwater. The response of freshwater DOC to global change will affect the size of global carbon sink, and structure and function of freshwater ecosystems. We reviewed the influence of global change on freshwater DOC, and the feedback of freshwater DOC dynamics to climate change. We pointed out that interactions among global change factors affected freshwater DOC, and the influencing degrees of global change factors varied with time and space. The feedback of freshwater DOC to global change was also substantially different across time and space. But there is little information regarding the feedback of freshwater DOC to global change, and much less is known about the feedback mechanism of freshwater DOC to global change. Based on present researches, more attention should be devoted to the three aspects: (1) to expand research areas to understand the temporal dynamic characteristics of DOC in freshwater ecosystems in different regions; (2) to better understand the effect of global change on DOC composition and structure in freshwater ecosystems; and (3) to gain better insight into the feedback degree and mechanism of freshwater DOC to global change.

Key words: winter wheat farmland ecosystem, flux footprint, the North China Plain., eddy covariance system