Abstract: Soluble organic nitrogen (SON) plays a significant role in nitrogen cycle and nutrient balance of terrestrial ecosystems, and is one of the most active constituents of soil nitrogen. SON can not only be transformed into mineral nitrogen through mineralization, but also be absorbed directly by plants. Meanwhile, SON loss may cause eutrophication in aquatic ecosystems, and aggravation of N₂O emissions in soil ecosystems as well. Therefore, SON has aroused multidisciplinary attention. In order to provide a reference for studying plant uptake and utilization of nitrogen as well as nitrogen cycle in ecosystems, this paper reviewed advances in SON sources, components, extraction, determination, ecological functions, and environmental effects of its loss. In addition, some prospects for further study on SON in soil were also proposed.

Key words: landscape plant, air temperature, relative humidity, canopy structural characteristics, Koelreuteria paniculata community.