Variation of Sstipa krylovii grazing grassland resources from 2003,2007, and 2010

Plant community diversity was investigated in 5 typical residential points of Stipa krylovii steppe during winter-spring and summer-autumnal seasons of 2003,2007,and 2010.The results demonstrated that there were almost 60 plant species in the fenced plots of S.krylovii steppe.The dominance index of S.krylovii and Leymus chinensis increased gradually for the two growth seasons during the whole studied period,while,the dominance index of Salsola collina——a symbol of grassland desertification,decreased gradually.There were also seasonal differences of plant community between two growth seasons.The dominance index of L.chinensis and Allium polyrhizum in summer-autumnal seasons was higher than that in winter-spring seasons whereas the dominance index of S.krylovii and Carex duriuscula in winter-spring seasons was higher than that in summer-autumnal seasons.The dominance index of the other species was similar in these two growth seasons.As stock-carrying capacity decreased or kept consistent,the dominance index of some zonal plant species such as S.krylovii and L.chinensis increased,whereas the dominance index of S.collina decreased sharply.S.collina gradually quitted from the rank of dominant species after stoct-carrying capacicty3.5 ha·livestock-1 three years.In S.krylovii steppe of Xilin Gol,the plant community successions of grazing grassland during 30 years correlated with the changes of grazing systems and ownership of grazing grassland induced by government reforms.Short-term plant community succession of plant community correlated with stock-carrying capacity.