Cleistogenes squarrosais a dominant C_4 species in the Inner Mongolia grassland.Its responses to global change and human disturbance can influence the structure,function,and service of the Inner Mongolia grassland.In this paper,we reviewed the photosynthesis,water use,and nitrogen use characteristics of this species and illustrated its physiological and ecological responses to grazing,precipitation variation, nitrogen addition,and desertification.Further ecological studies was required to examine the response of water use efficiency to global change and the underlying mechanisms,explore the nutrient relations with other plants,and the effect of the change of the biomass proportion in community on ecosystem carbon cycle.