Abstract: In normal season of grassland fire occurrence, the effect of different fire regimes on plant composition of Aneurolepidium chinense on Hulunber and Xilinguole grasslands is studied. The results show that on Hulunber grassland, the community density, species richness and diversity are increased, but the eveness is decreased after early spring burning. On Xilinguole grassland, the community density, species diversity and eveness are decreased, but the species richness is increased after Autumn burning. Continuous twice burning induces the increase of population density of A. chinense and several annual and biennial plant species, the decrease of community density and diversity of other populations, and the withdrawing of some species from the community.

Key words: Fire regime, Community composition, Aneurolepidium chinense steppe, migration, forest soil, stabilization mechanism., black carbon, organic carbon, soil type