Abstract: Nitrogen (N) is one of the most important pollutants in water. Riparian buffer zone, an ecological zone between terrestrial and aquatic ecosystems, performs excellently in removing N pollutants and thus is an effective way to control N output to water. Here, we introduced the process of N migration in riparian zone. The removal mechanisms of N by riparian buffer zone were elucidated from the perspective of physical, chemical and biological processes. We summarized research methods, removal efficiency and influencing factors of N reduction by riparian zone. Vegetation structure, soil permeability, and water holding characteristics, riverbank width and slope were the main factors affecting N removal by physical processes. Vegetation type, seasonal dynamics, and plant growth were the factors affecting N removal by plant assimilation. Soil temperature, organic carbon content, pH, nitrate and oxygen content contents were the main factors affecting N removal by denitrification. Finally, the problems in the current research and the future application were discussed.

Key words: Longxi River, Wenchuan earthquake, vegetation coverage, remote sensing., vegetation recovery