Grasshopper Species-Area Relationship on Ungrazed and Overgrazed Grasslands

The species richness and abundance of rangeland grasshoppers were investigated at 6 sites of ungrazed and overgrazed pastures in Inner Mongolia during the autumn of 1994.The ungrazed sites supported higher richness and density of grasshoppers than the overgrazed sites.The effects of overgrazing and ungrazing on the species-area relationships of grasshoppers were directty measured.The grasshopper assemblages from the 6 sites differed significantly in the intercept or in the slopes of their species-area regressions.The greater intercept and slope values of their species-area regression were found in grasshopper assemblages on ungrazed sites.In contrast to species-area relationship regression,the species increase rate with individual number was more rapid at overgrazed sites.Implications for conservation are discussed.

The species richness and abundance of rangeland grasshoppers were investigated at 6 sites of ungrazed and overgrazed pastures in Inner Mongolia during the autumn of 1994. The ungrazed sites supported higher richness and density of grasshoppers than the overgrazed sites. The effects of overgrazing and ungrazing on the species-area relationships of grasshoppers were directly measured. The grasshopper assemblages from the 6 sites differed significantly in the intercept or in the slopes of their species-area regressions. The greater intercept and slope values of their species-area regression were found in grasshopper assemblages on ungrazed sites. In contrast to species-area relationship regression, the species increase rate with individual number was more rapid at overgrazed sites. Implications for conservation are discussed.