Abstract: Research on ecosystem stability and state transition is important for evaluation of degraded grassland ecosystem health. We established a structuralfunctional state transition model (STSFM) based on the characteristics of grazing-induced degradation of Leymus chinensis grassland in the Xilin River Basin, Inner Mongolia. We systematically reviewed the grassland ecosystem states in the process of grazing-induced degradation of L. chinensis grassland and the characteristics of transitions among states. We further elaborated the instability of the grassland ecosystem and the unsustainability of grassland utilization. We found four different degradation states to form this STSFM in the degradation process of L. chinensis grasslands. Among these states, three states, i.e. nondegraded L. chinensis, slightly degradedStipa (S. grandis and S. krylovii), and moderately degraded Cleistogenes squarrosa communities, have similar environmental characteristics, and they can be positively or negatively transferred to each other. When the grassland is further degraded into Artemisia frigida community, the structure and function of the community will change, and environmental conditions will also deteriorate. Therefore, the restoration of A. frigidacommunity could not complete the succession to the former type, but will transfer into a new status with lower function. Our work enriches the theory of stability maintenance in grassland ecosystems and provides guidance for grassland restoration and utilization.

Key words: Inner Mongolia, grassland, ecosystem stability, grazing.