Study Of The Grazing-induced Erosion In Degenerated Succession Stages On Alpine Meadow In The Source Region Of The Yangtze And Yellow River, Qinghai-Tibetan Plateau,China

There are a large number of degraded grasslands in China due to climatic change and over grazing. And the degradation of grassland inevitably leads to soil erosion, so the soil erosion has become the dominant parading of grassland degradation in Source Region of the Yangtze and Yellow Rive and threatened the ecological security of our country and the survival and development of the pastoralists in the areas. The ecological system of this region is very fragile and the main land use pattern is grazing, so that the soil erosion type has its own characteristics. It has important significance to reveal soil erosion mechanism of alpine meadows, explore the grassland degeneration and build grassland recovery system by comprehensive analysis the factors which lead to soil erosion. According to this, the object of the study was investigating the barren patches in alpine meadows of Maqin country in Qinghai-Tibet plateau, China and establishing degradation sequence. We measured the surface temperature (underground5cm), the content of soil organic matter, soil particle size, soil erosion modulus and set up the digital elevation model. The main results are:1. The geometric features of barren patch in grazing grassland was calculated by GIS software (ArcView GIS3.2a) using digital imaging to measure the fractal characteristic of barren patches. It provides a new innovative technique in grazing ecology to explain the complicated problem of barren patch appearance in grazing grassland.2. The statistical analysis of surface temperature in degenerated succession stages on alpine meadow showing that the more serious of degradation the more strong of heat island phenomenon. The relationship among>0°accumulative temperature, the area percentage of barren patch and Soil organic matter could described by bivariate regression model(R2=0.957, P=0.043<0.05).3. This study using137Cs tracer technique to investigate soil erosion modulus in the sample site, the result showing that, the Extreme degraded site(101529.86t/km2·a)> Heavy degraded site(101529.86t/km2·a)>Medium degraded site(101529.86t/km2·a)>Non-degrade site(101529.86t/km2·a).4. To established regression model between soil particle fractal dimension (x1), slope (x2), soil organic matter (x3) and soil erosion modulus (y) of the sample site in degenerated succession stages on alpine meadow, the regression equation is:y=101818.856x1+174.652x2-1551.835x3-278374.217(R2=0.722, P=0.000)...