Inter-specific Relations Of Stipa Breviflora Desert Steppe Community At Different Stocking Rates

In order to clarify the effect of different stocking rates on inter-specific relation of the desert steppe community, change mechanism of the important value of communities and inter-specific association were analyzed at different stocking rates. On the basis of conducting a quadrat survey on each community, the research methods such as X2 test, Pearson correlation coefficient and Spearman rank correlation coefficient test were used to make inter-specific association and correlation Analysis, and acquired results showed as following.Changes of the important value of species showed that species'composition and structure had variation in different intensities of stocking disturbance, that dominant species'status took place replacements: under heavy grazing, the most dominant specie was Salsola collina Pall., it was Cleistogenes mutica Keng under moderate grazing, and Artemisia frigida Willd. under light grazing, Cleistogenes mutica Keng in forbidden grazing control group.With the strengthening in intensities of stocking disturbance, species to significant correlation (including very significant) showed decreasing trend. It was the most and the negative significant correlation (including very significant) being higher than the significant correlation (including very significant) in forbidden grazing control group. There is similar negative significant correlation (including very significant) and the significant correlation (including very significant) in lighter grazing. There is more negative significant correlation (including very significant) than the significant correlation (including very significant) in sever grazing. These result showed there was more stable community in moderate grazing intensity and forbidden grazing control group compared with higher grazing intensity.In Stipa breviflora desert steppe community, the association between species mostly showed negative correlation although the amount of species to significant and very significant was less, and the more association between dominant species showed negative significant correlation in different grazing intensities. These result showed that In Stipa breviflora desert steppe community, differentiations were happened between communities during long-term succession and each species occupied a certain ecological niche, however, due to limited resources, mostly association had not been stable, environment and resource competition between species was fierce, and communities were still at succession period.