Abstract: To explore the effects of grazing on the vegetation communities and soils in the lowland. This study analyzed the above-ground biomass, important value of species,vegetation dominance, species richness, Shannon-Wiener diversity index, Pielou evenness index, Simpson ecological dominance index, 0-10cm soil clay, soil silt, soil sand, soil organic carbon and total nitrogen content in the lowland between the Hunshandake Sandy Land. The results showed that:(1)above-ground biomass, soil clay, soil silt, soil sand, soil organic carbon and total nitrogen content were significantly different under different grazing levels (P<0.01), The difference of species richness, Shannon-Wiener diversity index and Pielou evenness index were not significant at different grazing levels (P>0.05), and the Simpson ecological dominance index was significantly different under different grazing levels (P<0.05). (2)The grazing area was dominated by Gramineae,the above-ground biomass of Gramineae vegetation accounts for 54.88%-57.76% of the whole vegetation community; the above-ground biomass of heavy grazing area was 63.59 g·m^-2, which was 26.61% lower than the light grazing area. (3)Leymus chinensis and Setaria viridis were the dominant species in grazing areas, with important values corresponding to 14.16% (heavy grazing areas) and 19.10% (light grazing areas), 13.40% (severe grazing areas) and 15.42% (light grazing areas). The important values of heavy grazing under the Bassia dasyphylla、Stipa krylovii and Artemisia scoparia were significantly higher than those of light grazing, while L. chinensis was lower than the light grazing area. (4)Heavy grazing exacerbated soil desertification, increased sand content, decreased grassland productivity, and decreased soil organic carbon and total nitrogen content.

Key words: grazing, lowland, vegetation community, soil, Hunshandake Sandy Land