Abstract: In order to provide scientific data to inform decisions on the restoration of wetland on the Qinghai-Tibet Plateau, a study was conducted of degraded alpine river wetlands in the source area of the Yellow River in Three-River Headwaters Region, and scattered sites forming a degradation time series were selected to represent the different wetland degradation stages. The plant community and soil physical and chemical characteristics across the alpine wetland degradation series were analyzed to elucidate the process of wetland degradation. Soil pH (0-20 cm soil depth) was 8.0 for undegraded wetland, but was significantly higher (8.5-9.0) in the various stages of degradation, though without any clear time-trend. With degradation, the vegetation height, coverage and biomass decreased gradually, the community structure became more complex; the soil salt enrichment layer gradually moved downward in the profile, the soil total carbon content and soil water content decreased significantly, and the alkali nitrogen content was reduced. Across the degradation series, the total phosphorus content tended to increase, while the available phosphorus content showed no significant changes. In general, the results show that the changes in soil moisture content were the main driver of degradation in the Maduo River wetland, and the degradation most affected the height of the plant community. With increasing intensification of degradation, soil water moisture and total carbon decreased significantly. Changes in soil moisture were closely related to changes in the community structure.

Key words: degraded wetland, alpine river wetland, vegetation community structure, soil nutrient