Abstract: Silicon, with the abundance of 28.8%, is one of the most abundant elements in the earth’s crust. It is a beneficial element for the growth of most plants. In ecosystems, silicon cycle is closely related to the cycles of carbon and other nutrient elements. Most researches of silicon cycle are focused on marine or terrestrial ecosystems. Few studies focused on the processes of silicon cycle and their effects on carbon and nutrient cycles in lake-watershed systems. This review summarized the speciation and distribution of silicon in lake-watershed systems, elaborated the basic processes of silicon cycle in lakewatershed systems, and illustrated the underlying mechanisms for the controlling of silicon cycle on carbon and nutrient cycles. We suggest that futureresearch should analyze silicon sources of lakes and quantify the amount of carbon sequestered by phytoliths and diatoms in lake sediments. It is necessary to strengthen the study on the stoichiometric relationships of nitrogen, phosphorus and silicon in lakes and to build ecosystem models coupled with silicon carbon-nutrient cycles for lake-watershed system. This review is helpful for fully understanding silicon cycle and its effects on carbon and nutrient cycles, and provides reference for mitigating the eutrophication of lake-watershed systems and the impacts of global climate change.

Key words: nitrogen addition, species, leaf, non-structural carbohydrates