The Research On The Intercorrelation Of The High-cold Ecological System And Uncultivated Cold Soil Environmental Response In The Headwaters Of The Yangtz And Yellow River

The high-cold ecosystem in the headwaters of the Yangtze and the Yellow River is a special one with a simple ecological structure and easy to be influenced. Due to the variation of the global environment and the influence of human activities, the high-cold ecological environment in the headwaters degrades to a different degree. The cold and virgin soil environment formed under the high plateau cold climatic condition is a significant component of the high-cold ecosystem. The degradation of the cold and virgin soil environment will profoundly influence the high-cold ecological environment and ecological balance. This article explains the correlations between the cold virgin soil environment in the headwaters of the Yangtze and the Yellow River and the high-cold ecosystem. By choosing the typical samplings and plots in the headwaters of the Yangtze River and the Yellow River, we carefully studied the physical and chemical properties, the soil moisture, the vegetation variation and the soil erosion of the cold virgin soil in the target area, we drew the following conclusion in the end:1. The soil environment in the target area is intensively changed under the variation of the global environment and the interference of the human activities. Both the physical and chemical properties of the soil degrade. The degradation of the soil leads to the increase of the topsoil granule, the increase of soil unit weight and the increase of sand content in the soil. In the heavily-degraded sampled area, the rockbase is uncovered, the soil is heavily granulated. Simultaneously, the soil-layer is thinning. The chemical compositions of soil also varied correspondingly with the degradation of the soil (including organic carbon, N, P and other micro-elements). The variation of the physical and chemical properties is closely correlative with the intensity of the soil degradation.2. The hydrological properties of the soil vary after the degradation. The moisture content, permeability, saturation and water-conductivity of the soil all vary to a different degree. The soil moisture content decreases after the degradation of the soil, which is closely related with the vegetation coverage. The comprehensive ecological index value decreases by 67%, the water-conductivity increases 12-17 times and the variational rates of which are 90.3% and 93.7% respectively with the variation of the soil depth. The changing process of the soil moisture varies differently according to the slope, the depth of soil and the vegetation condition after a rainfall. In three sampled areas with a different vegetation coverage (30%, 68%, 92% respectively), the runoff quantity is 0.3038m3, 0.1605m3, 0.1656m3 correspondingly.3. The vegetation groups change with the degradation of the soil. The original superior groups decrease and other protective vegetation and weeds prosper, which leads to the changes of vegetation types. The varieties of living things of the productivity of the soil decrease correspondingly. The vegetations show a tendency of undersizedness and the soil environment degrades as well.4. Making a confirmation of the area and quantity of the soil erosion, under the coverage of different vegetation in the headwaters of the Yangtze and the Yellow River by using ¹³⁷Cs tracer and remote sensing data diagram.