Effect Of Soil Physical Character And Plant Community In Leymus Chinensis Steppe Under Grazing Intensities

The experiment was carried out in Leymus chinenesis steppe in the Xilin River Basin. According to the classification method of rangeland degeneration series of Li Bo, 4 grazing intensities, normal, light degraded, moderate degraded and heavy degraded were determined. Soil physical characteristics and vegetation characteristics under different grazing intensities, also including the relationship between soil physical characteristics and vegetation characteristics were discussed. The result showed that with the increasce of grazing intensities:(1) the compaction and bulk density of soil increased;(2) but soil moisture content decreased, which had great relevance with rainfall; (3)soil porosity degree had tendency first with decrease, then increased, and decreased in the end; (4) the richness and diversity indies of plant community in the 4 levels were not relevant; (5) the richness of the heavy degraded plant community in 2005 was smaller than others',which in 2006 the value was as equal as moderate degraded's,but small than others'; (6)above-ground biomass, vegetation coverage and net biomass of rangeland indicated an obviously decreased trend; (7) vegetation coverage had little relevance with the compaction and bulk density of soil, but obvious relevance with soil moisture content and soil porosity degree, the coverage of litter had obvious relevance with biomass of plants. Accordding to the relevance, build Linear Regression Models,such as plant coverage with soil porosity degree, soil moisture content; biomass of plants with the coverage of litter, biomass of plants with soil moisture content; the coverage of litter with soil moisture content.