A Study On Grazing Degenerate Sueeession Of Meadow Steppe In Inner Mongolia

The trial was conducted in meadow steppe in Inner Mongolian from. 2005a to 2008a. Four grazing degraded stages of control, light, moderate, and heavy grazing were set up in order to understand grassland characteristics and soil physical properties. The results are as follows:1. The different grazing intensities were classified by utilization factor of vegetation.2. The grazing intensity and the climate have significant influence on the net primary productivity. The changes of litter under different grazing intensities were obvious, namely CK>LG>MG>HG. Plants became smaller with grazing. LG and MG obviously increased the species number. Plant reproduction was affected by precipitation and grazing intensity and no obvious change regulation with them.3. Grass functional group plays a significant ecological role in the plant functional groups. The functional groups show better climatic stability under control and moderate grazing. The importance values of the main plants are different and consistency among years, which made grassland in different succession stages under different grazing intensities.4. Soil bulk density and soil compaction increased with the increase of grazing intensity. Soil moisture content had the tendency of decrease, which had few relevance with rainfall. Sand content decreased with the increase of grazing intensity while silt content increased. No significant change was accrued in clay. Sand content increased with the increase of soil depth, clay content did not change significantly by reducing silt content.5. Soil organic matter decreased with the increase of grazing intensity. Grazing made the soil total nitrogen increase in soil surface layer. Grazing was benefit to soil total phosphor accumulation, but in different intensities the differences were not obvious. Grazing increased soil available nitrogen accumulation. Soil available phosphor in surface layer increased in HG, and output of phosphor increased obviously in subsoil. Soil available potassium increased with the increase of grazing intensity.