Abstract: In order to understand the effects of grazingprohibition on the species diversity of typical steppe, the species composition of typical steppe in Xilinguole of Inner Mongolia was investigated under the conditions of free grazing and of grazingprohibition since 1987, 1997, and 2003. The results showed that grazingprohibition did not change the composition of dominant species markedly, but affected the relative importance of the species, with the dominance of dominant species increased. At the same time, grazingprohibition enhanced the species diversity of the typical steppe in a definite period of time, but, as the period of grazingprohibition extended, the species diversity and the richness of the typical steppe decreased. Moreover, under the same conditions of grazing or grazingprohibition, the steppe with better water condition had higher species diversity. It was concluded that an appropriate duration of grazingprohibition and favorable water condition was in favor of the maintenance of the species diversity of typical steppe, and the decline in species diversity of typical steppe in the region could be ascribed to the overgrazing and droughty environment condition.

Key words: Moss, Culture medium, Light culture, Growth hormone