Study About Community And Soil Characteristics Under Different Utilization Patterns On Fenced Grassland In Hulunbeier Leymus Chinensis Meadow

Conducting the study about different utilization patterns on the fenced grassland of Leymus chinensis meadow provided some scientific basis for reasonable utilization and sustainable development of grassland. The fenced grassland of Hulunbeier Leymus chinensis meadow as the research object was studied. And the experiment was control by setting six kinds of utilization ways:the grazing prohibition, light grazing, heavy grazing, continuous mowing, biennial mowing and mowing+grazing. The experiment had conducted a comparative study on several aspects of grassland, including the composition of vegetation community, community characteristics, species diversity, grassland biomass, soil bulk density, soil water content, soil organic carbon content, soil total nitrogen.The result indicated that:1. Under different utilization ways, the important value of various plant species in community had changed. The important value of the community constructive specie-Leymus chinensis was the highest under grazing prohibition and it was the lowest in continuous mowing. The important value of the community companion specie -Carex duriuscula was the highest under heavy grazing. In addition, community different functional group under different using ways showed different changing trends. In the aspect of plant life-form function groups, the percentage and relative biomass of the annual and biennial plants declined with utilization degree aggravating; the miscellaneous perennial herb plants and semishrub changed unobviously. In the aspect of water ecological functional group, the percentage and relative biomass of mesophytes significantly lowered.The percentage of xerophytes and mesoxerophytes showed an increasing tendency with utilization degree aggravating, but the relative biomass of xerophytes and mesoxerophytes had less obvious changes.2. The community characteristics of grassland vegetation changed significantly under different utilization ways. The height of community from high to low was:grazing prohibition, the biennial mowing, continuous mowing, mowing+grazing, light grazing, heavy grazing. The change of community coverage was:grazing prohibition> light grazing> biennial mowing> continuous mowing> mowing+grazing> heavy grazing. The change of community density was:continuous mowing> heavy grazing> light grazing> mowing+grazing> grazing prohibition> biennial mowing.3. Under different utilization ways, the alpha diversity of community species changed significantly. Margarlef index, Shannon-Wiener index, Simpson index and Pielou index both changed " increasing-decreasing" with the utilization degree aggravating. Each index was the highest under mowing+grazing and everyone was the minimum under heavy grazing. And the two utilization ways had significant difference. The beta diversity (Whittaker index) of grassland vegetation under heavy grazing got the maximum and under grazing prohibition got the minimum.4. The change of grass aboveground biomass showed decreasing with utilization degree aggravating. Under grazing prohibition, the aboveground biomass was the highest. Under heavy grazing, the aboveground biomass was the minimum. And they had significant difference between two utilizations. The biomass of leymus chinensis also showed the same regularity. And it's higher under mowing using than under the grazing using. The distribution of the grass underground biomass with soil depth presented a type "T".The change of underground biomass was:biennial mowing> mowing+grazing> light grazing> grazing prohibition> heavy grazing> continuous mowing.5. The water content of the each soil layer under different utilization ways had significant difference. It in grazing prohibition and light grazing was significantly higher than it in continuous mowing and heavy grazing. The soil bulk density of grass surface (0-10 cm) changed significantly with different utilization ways. The soil bulk density showed increasing trend with the utilization degree's aggravating and it was significantly higher under heavy grazing than it in grazing prohibition and light grazing. In 10-20 cm and 20-30 cm soil layer, the difference of soil bulk density under different utilization ways was not significant.6. The soil nutrients (organic carbon and total nitrogen) of grassland centrally located in the 0-10 cm soil layer. The soil nutrient content had changed significantly under different utilization. In 0-10 cm soil layer, the organic carbon content showed the highest under grazing prohibition and showed the lowest under heavy grazing. The total nitrogen content showed the same ruler. It was the highest under grazing prohibition, but it was the lowest under continuous mowing. In 10-20 cm,20-30 cm soil layer, the soil organic carbon content and the soil total nitrogen content were the lowest under heavy grazing and had no significant difference between other five utilization ways.