| The typical grassland in Inner Mongolia was taken as the research object; experimental design of randomized block was adopted to study the influences to Stipa grandis steppe community characteristics from three kinds of cutting system (twice-a-year mowing, once-a-year mowing, mowing 50 meters and retain 10 meters everyear) from 2011. Ecological model was introduced to analyze the abundance distribution of plant species; Power function rule was applied to explore the changes of spatial heterogeneity of phytocoenosium, the main research results were as follows, 1. The once-a-year mowing would lead to species reduction in Stipa grandis grassland, the importance value of the species with poor mowing resistance and relatively high plant height, such as Leymus chinensis, Astragalus galactites, Ephedra sinica would be reduced, while the importance value of the species with strong mowing resistance and relatively low plant height, such as Cleistogenes squarrosa, Corispermum hyssopifolium would be increased, but the dominant species in the community did not change. There were no significant changes of the height and cover degree in the community (P>0.05); The biomass with mowing in successive years was significantly lower than control group and the twice-a-year mowing area (P<0.05); The mowing would significant increase the a diversity in the community. Thus the twice-a-year mowing was more reasonable. 2. The overlapping-niche model could fit the species abundance distribution in different mowing and control group area better; the short-term mowing could not change the species abundance distribution. 3. The spatial heterogeneity of Stipa grandis typical grassland vegetational community was higher than the random distribution, mowing could increase the spatial heterogeneity of the community. The changes of the spatial heterogeneity after mowing were different due to the biological characteristics of the plants and the different pressure adaptive strategies to the mowing. |
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