Abstract: Leaching of dissolved organic carbon (DOC) is a key process in carbon cycling of terrestrial ecosystems. Forests are one of the main sources of DOC in terrestrial ecosystems. DOC can reach the bottom layer of soil through leaching, resulting in changes of organic carbon in the bottom layer of soil. The DOC in forest ecosystems enters water systems through surface runoff and groundwater seepage, and finally participates in marine carbon cycle. Therefore, exploring the underlying mechanisms of DOC leaching in forest ecosystems is of great significance for understanding key processes of global carbon cycle. Here, we reviewed the sources and sinks of DOC in forest ecosystems, and summarized several important underlying mechanisms of DOC leaching, including land use changes, climate change, acid deposition, atmospheric CO₂ increase, soil Fe-Al oxides. The advantages and disadvantages of empirical statistical models and process-based models for simulating DOC leaching and output fluxes were summarized. Considering the current status and shortcomings of DOC-related researches in forest ecosystems of China, we propose to establish a DOC leaching observation network across forest ecosystems in China to provide accurate and solid data for predicting DOC changes. Moreover, field observations, laboratory experiments, and model simulations should be combined to explore the underlying mechanisms of DOC leaching in forest ecosystems. It is necessary to strengthen the modeling of DOC leaching at typical regional and national scales in the context of environmental change.

Key words: light-response curves, tillage practices, winter wheat, diurnal variation of photosynthesis, grain yield.