Studies on Community Stability under Different Grazing Systems on Desert Steppe

A comparative study on plant importance values and community diversity under different grazing systems was conducted in desert steppe of Inner Mongolia Plateau. The results showed that the importance values of Stipa breviflora, Cleistogenes songoriea, Allium polyrhizum and C. squarrosa were higher in the rotational grazing area and in closed area than in the free stocking area, while the importance values of annual plants were higher in the free stocking area. In year 2002, Shannon-Wiener index, Simpson index, and Pielou index were all found higher in the free stocking area than in the rotational grazing area. However, the distribution of importance values for the influential factors with these indexes was concentrated on several dominant and constructive species, which indicated that rotational grazed grassland was more stable than the free stocked one.