Algal crusts represent a crucial type of biological soil crust in desert grasslands and serve as an important significant “ecological engineer”. They play a vital role in soil stabilization， water retention， wind erosion resistance， and carbon and nitrogen sequestration. However， researches on the effects of different grazing intensities on the characteristics of algal crusts in desert grasslands remains relatively limited. Based on a long-term grazing experiment platform （2004-present） in the desert grassland of Siziwang Banner， Inner Mongolia， in this study we investigated the impacts of varying grazing intensities on the algal crusts characteristics and identified the key driving factors. We measured the coverage， thickness， chlorophyll-a content of algal crusts， as well as related soil physicochemical properties under different grazing intensities. The results showed that as grazing intensity increased， the coverage， thickness， and chlorophyll-a content of algal crusts significantly decreased （P<0.05）. Structural equation modeling further revealed the key soil factors driving changes in algal crusts， among which soil available nitrogen was the most critical factor influencing characteristics of algal crusts. This study demonstrated that moderate and heavy grazing significantly inhibited the growth of algal crusts in desert grasslands， with soil bulk density， capillary water holding capacity， and soil available nitrogen were the most closely related factors to the changes in algal crusts characteristics. To maintain the ecological functions of algal crusts in desert grassland ecosystems， it is essential to strictly control grazing intensity， as long-term high-intensity grazing will lead to their severe degradation.

Desert steppe  /  Algal crusts  /  Grazing intensity  /  Soil physical and chemical properties