Abstract: Plant characteristics can indicate the function and structure of grassland ecosystems. A field experiment was conducted to examine potential impacts of different land management systems on the dominant grassland species (Stipa krylovii and Cleistogenes squarrosa) in a typical steppe in Inner Mongolia, China. The characteristics of the two dominant species were described under three land management systems; continuous grazing, 1995 enclosure and 2003 enclosure (livestock excluded). Above-ground biomass, the distribution of above-ground biomass and below-ground biomass are reported. Land management significantly affected above- and below-ground biomass of both species (P<0.05). Compared with the enclosed areas (1995 and 2003), continuous grazing reduced total above-ground biomass, leaf biomass, stem biomass and seed biomass of both species (P<0.05) but increased below-ground biomass of both species (P<0.05). The C₃/C₄ ratio was higher in enclosed areas than under grazing (P<0.05).