Studys Of The Characteristic Of Vegetation And Soil And Indication Under The Different Degeneration Degree In The Meadow Steppe

The characteristics of community and structure, The physical and chemical characteristics of soil, the amount of microbes of soil in the Leymus chinensis +forb community and Stipa baicalensis + Leymus chinensis community under the different degeneration scale were investigated in 2007 and 2008. The data obtained from the experiment were analyzed with the principal components, the canonical correlation and fuzzy comprehensive evaluation method, which obtain coefficient of different degradation scale known as indication. The results were shown as follows:1. The composition of community species was gradually unitary, quantity reduced, the important value of species and the composition of Family-Genus varied obviously, and the perennial plants gradually reduced with grassland degeneration. The coverage, height, above-ground biomass, surface litter and the underground biomass of grassland community reduced obviously with grassland degeneration. The indexes ofα-diversity of community decreased obviously, the index ofβ-diversity of community increased gradually, and the similarity coefficient of community in the different degeneration scale was a declining trend with grassland degeneration.2. The physical and chemical characteristics of soil in the 0～10cm soil layer were obviously changed. The soil coarse particle and bulk density were significantly increased. Soil moisture content was significantly decreased. The soil organic matter content and the soil total nitrogen content were significantly higher in light degradation (LD) than in heavy degradation (HD) and moderate degradation (MD). The available nutrient varied significantly, but the pH had no significant change. The amount of bacterium and ray fungi reduced obviously, and the amount of fungus increased obviously.3. There were no consistent correlation between vegetation and soil factor under different degeneration scale at Leymus chinensis +forb community and Stipa baicalensis + Leymus chinensis community.4. The indication of MD and HD, according to the fuzzy comprehensive evaluation of vegetation and soil, at Leymus chinensis +forb community, were 0.7426 and 0.5611, respectively, and at Stipa baicalensis + Leymus chinensis community, were 0.7702 and 0.59804, respectively.