Effects of Grazing Intensity on Vegetation in Sandy Grassland of Horqin

To study the variation of vegetation characteristics in different grazing intensities in sandy grassland of Horqin sandy land,we contracted the variation of vegetation characteristics,such as cover,community composition,species diversity,above-under-ground biomass and litter biomass in enclosed,moderate grazing and heavy grazing sandy grassland.The results were as follows:(1)The dominant plant was annual among enclosed,moderate grazing and heavy grazing sandy grassland,but the dominance of grasses in enclosed and moderate grazing sandy grassland was higher than heavy grazing,the dominance of annual of heavy grazing sandy grassland was the biggest;(2)Grazing intensity had significant impacts on cover,aboveground biomass and litter biomass;and with the increase of grazing intensity,cover,aboveground biomass and litter biomass were declined;(3)The differences of species richness and diversity of enclosed,moderate grazing and heavy grazing sandy grassland were not significant.(4)The grazing intensity,the depth of soil and their interactions had significant impacts on underground biomass.The total underground biomass was decreased with the increase of grazing intensity.While,the underground biomass of three different soil depth in heavy grazing sandy grassland was not significant.Grazing changed the community composition of sandy grassland,and the cover and productivity were greatly reduced.Especially,heavy grazing dramatically increased the advantage of annuals,and had the greatest effect on the decrease of shallow rootsdistribution.