Abstract: We comprehensively evaluated the quality of a desert grassland in Yanchi County under three grazing intensities, including fence enclosure (NG, i.e. no grazing), moderate grazing (MG, moderate grazing), and heavy grazing (HG, heavy grazing). Using principal component analysis and path analysis, we compared the differences in grassland vegetation and soil physicochemical properties under different grazing intensities, aiming to provide theoretical guidance for the restoration and reconstruction of degraded grassland ecosystems. The results showed that plant biomass under NG treatment was 10.78% and 74.85% higher than MG and HG treatments, respectively, and plant height and coverage increased by 31.21%-131.27% and 26.03%-93.29%, respectively. Macroaggregates with a particle size >0.25 mm were the main soil mechanical stable aggregates under NG, and microaggregates with a particle size <0.25 mm dominated under HG. The proportion of soil water stable aggregates with a particle size >0.25 mm, the average mass diameter and geometric mean diameter of surface soil water stable aggregates under different grazing treatments were in the order of NG > MG > HG. Soil nutrient supply potential, soil nutrient supply intensity, and soil comprehensive quality under NG treatment were significantly higher than those under HG treatment. We concluded that enclosure is a suitable measure for ecological restoration of grasslands, due to its positive effects on grassland vegetation, soil structure, and soil fertility.

Key words: desert grassland, soil aggregate, soil fertility, biomass