Effects On Plant And Soil Of Human Disturbance In Xilamuren Grassland

This paper take Xilamuen grassland as research object. By using the priciples and methods of plant ecology and soil science, depent on the mean which is combine field survey and laboratory simulation tests together, study on the changes and the relationship between soil physical and chemical properties and vegetation characteristics under four human disturbance methods those are irrigation, enclosing, grazing and tourism in Xilamuren grassland, this paper has reveal the changing features of grassland vegetation and soil under different human disturbances. Results are as follows.(1) The human disturbance has significant effects on grassland community structure. From irrigation area to tourism area, all the plant height, coverage, density, aboveground biomasses show decreasing trend. With revegetation, all the species abundance index, diversity index and uniformity index take increaseing trend significantly, and the ecological dominance reduce significantly, the similarity index only is 0.38 between irrigation area and tourism area.(2) In the 0-30cm soil layer, the bulk density of tourism area are higher than enclosing area, grazing area and irrigation area and the number is 6.67%,15%and 16.79% respectively. In Xilamuren grassland, because of the human disturbance such as over-grazing and unreasonable tourism method, the particulate matter of the soil was blowned gradually by wind erosion and the soil began to change in to coarsening and singling.(3) The soil moisture content changing rule is: irrigation area>enclosing area> grazing area> tourism area. Cover with gravel can control the soil evaporation effectively. By this, the evaporate speed can slow down in the evaporation prophase and there are still contain more soil moisture in the anaphase, so it can provide more water for the growth of vegetation.(4) In the 0-30cm soil layer, from irrigation area to tourism area, all the means of organic matter, total N, total P, available N, available P, and available K show reducing trend. With the increasing of the soil depth, the influence of human disturbance on soil nutrient is decreased. All the plant average height, coverage aboveground biomass and biodiversity has positive correlative relationship with soil nutrient and negative correlative relationship with soil bulk density (p<0.05).