Effects Of Grazing Intensity On Community Characteristics And Spatial Distribution Of Stipa Breviflora On Desert Steppe

Desert steppe is dominate by Stipa breviflora,which is one of the important part of the Inner Mongolia grassland.Grazing is the main use of the grassland in the area.In this study,plant community Characteristics,spatial heterogeneity of plant community and the distribution pattern of species abundance in grassland ecosystem under different stocking rates were studied by field experiment and indoor mathematical analysis.The objective is to illustrate the effects of grazing on plant community Characteristics,spatial heterogeneity and spatial distribution of plant community and the distribution pattern of species abundance and to provide basic information for sustainable utilization for desert steppe.The results are as follows:1.The aboveground biomass,plant height,density and coverage of plant communities varied with year and grazing intensity(P<0.05).The biomass decreased as grazing intensity increased in every year(P<0.05).Community coverage in heavy grazing treatment was significantly lower than that of the control(P<0.05),moderate and light grazing(P<0.05).The density of the moderate and heavy grazing areas was significantly lower than that of the control(P<0.05).2.Grazing intensity and year both had effects on a species diversity of the community.Grazing intensity and year interacted with year in terms of their effects on Pielou index.The increase of grazing intensity resulted in a significant decrease in species diversity(P<0.05),and the effect of grazing intensity on species diversity was greater than that of year.3.The effect of grazing intensity on the number of species was higher than that of year.The number of species decreased with the increase of grazing intensity.The number of species in control,light,moderate and heavy grazing area was 24,21,21 and 19,respectively(P<0.05).The frequency of different species was various under different grazing intensity.S.brevfilora was significantly increased with the increase of grazing intensity(P<0.05),and Cleistogenes songorica has the same tendency of the change with that of S.brefilora.Artemisia frigida and Convolvulus ammannii increased significantly with the increase of grazing intensity(P<0.05).4.The geometric progression model can optimally fit the species abundance pattern of desert grassland,and the pattern of species abundance was not changed by year and with the change of grazing intensity,while S.brevflora.plays a key role in the species abundance pattern of desert steppe.5.The spatial heterogeneity of the community was the same in each year,but spatial heterogeneity of the community was higher than the random distribution in each grazing intensity,and the spatial heterogeneity of the community increased with the increase of grazing intensity.The heterogeneity index of Stipa S.breviflora and C.songorica was higher than that of community heterogeneity in each grazing intensity.