Effects of grazing on structure and productivity of functional group of steppe communities in middle section on northern slope of Tianshan Mountains

By dynamic measuring,the community structure and functional group productivity of Festuca ovina steppe in the middle section on northward slope of Tianshan Mountains were studied.The results show that the structure of life forms and functional group in F.ovina steppe community were not changed,and perennial grasses with high quality occupied predominantly under grazing conditions.They were ranging separately at 30.74%～44.99% and 30.81%～35.71% under grazing and no grazing.Moderate grazing could increase the number of plant species in community,but the dominating status of F.ovina,Stipa capillat and Carex liparocarpos had not been changed with their dominances ranging as 11.64%～19.40%,11.05%～19.70% and 11.65%～23.79% respectively.In the components of functional group of life form,positive correlations of biomass existed obviously among shrubs and half shrubs,perennial grasses,forbs,perennial legumina,grasses and forbs,and the ecological compensation effects were significant.