Influence of Fire Factor on Leymus chinensis Population in Inner Mongolia Steppe

With the method of prescribed burning, the effects of burning on Leymus chinensis population in Inner Mongolia steppe were discussed. The results showed: fire could produce unfavorable effects on the shoot development of L. chinensis, restrain the height, and decrease the dry weight per shoot. But fire could greatly promote the density and increase aboveground biomass of L. chinensis community, which showed that fire could play a positive role in promoting the development of L. chinensis population. According to the results, appropriate burning every several years (about 4～5 years) would have positive effects on the development of L. chinensis population, the effects may maintain 4～5 years. But repeated burning in successive years had unfavorable effects on L. chinensis. Moreover, the effects of fire on L. chinensis population were influenced strongly by the condition of environment; fire had unfavorable effects on L. chinensis in Stipa grandis community where the water condition and physicochemical properties of soil were relatively bad.