Abstract: Over-grazing on the Tibetan Plateau is a human disturbance that has occurred for a long time. It has seriously harmed the structure, function, and services of the alpine meadow ecosystem. Because of its simplicity and effectiveness, enclosure has been widely used for the restoration of deteriorated grassland. However, it can have positive and negative effects, so it is vital to assess the quality of grassland under enclosure systematically and scientifically. The aim of this study was to comprehensively assess the quality of an alpine meadow after 7 years of enclosure. The quality of the alpine meadow was analyzed by determining community biomass, species biodiversity, and soil physico-chemical properties. After 7 years of enclosure, most of the indexes related to soil physico-chemical properties had improved to a certain extent, but only nitrate N had increased significantly (by almost double). Community biomass and plant litter were 35.73% and 65.75% greater, respectively, in the enclosed area than in the grazed area. However, there was no significant difference in species diversity between the enclosed and grazed areas. A principal component analysis showed that the soil quality was better in the enclosed area than in the grazed area (mean comprehensive scores of 0.1 and -0.02, respectively). The effects of various factors on meadow quality were evaluated by analyzing the association between biomass weight values and certain indexes. The meadow quality was restored after 7 years of enclosure, and this was largely due to improved soil physico-chemical properties. In summary, enclosure plays a positive role in restoring deteriorated alpine meadow. Further studies should assess the restoration effect of enclosure on deteriorated grassland at regular intervals to understand the timing and duration of its restorative effects.

Key words: fence, grazing, grassland quality, soil physic-chemical properties, community biomass, species diversity