Study On Effects Of Different Vegetation Restoration Patterns On Soil Aggregate In Pingshuo Opencast Mine

Soil aggregate is the main component of soil. It has an important effect on soil physical and chemical characteristics. The quality and quantity of soil water stable aggregate were selected as the main index to assess soil erodibility. In recent years, land reclamation in opencast mine effected by the factors of anthropogenic disturbance is very large. It could improve the ecological environment of ATB opencast mine by vegetation restoration. Based on the study of changes in soil aggregate within the soil depth of 0~20cm under different vegetation restoration mode, the relationship between soil aggregate and the physical and chemical properties of soil, and the characteristics of soil aggregate organic carbon of the ATB opencast mine, this thesis will provide theoretical basis for this opencast mine to choose appropriate vegetation restoration pattern. The research results of this thesis mainly include the following contents:(1) The content of water stable aggregate greater than 0.25 mmin the soil study area is between 7.62% and 40.28%;the values of MWD and GMD are between 0.71 and1.06, and between 0.25 and0.42 respectively. The fractal could reflect physical property and the nutrition of soil, ATB opencast mine’s the fractal dimension of soil aggregate is between 2.884 to 2.991. The more stable aggregate structure, the less fractal will be. The sample areas of SIII(Pinus x Ailanthus x elm) and SIV(Pinus×Robinia)are the highest in the content of water stable aggregate, the values of MWD and GMD, and the lowest in the fractal dimension, and there is an extremely significant negative correlation between fractal dimension and soil water stable aggregate. Comprehensive analysis of the above three, the vegetation restoration pattern of SIIIand SIVis the most appropriate pattern for ATB opencast mine.(2) The soil of study area is alkaline, most of the study area’s pH value is less than Original topography and no reclamation land. It reflect that the vegetation restoration lead pH value to neutral, and make appropriate soil pH value suitable for plant growth. Although the effect of increasing the content of soil water stable aggregate for improving the soil total phosphorus and available phosphorus is not significant, it helps to improve the content of soil organic matter, total nitrogen, total potassium and other nutrients, and the sample plot of SIV shows the best effects.(3) The soil aggregate organic carbon basically shows the tendency of the larger size of aggregate, the higher of its content. The content of soil aggregate organic carbon in the sample plot of SIV is much higher than other plots. The content of soil aggregate organic carbon greater than 0.25 mm accounts for higher proportion of total organic carbon than the content of soil aggregate organic carbonless than 0.25 mm, and there is an extremely significant positive correlation between soil water stable aggregate organic carbon and total organic carbon.(4) The study concluded that vegetation restoration pattern in opencast mine in the sample plot of SIV shows the best effects. In the future, the SIV mode should be given priority in the vegetation restoration in opencast mine, as well as taking into account of other vegetation pattern, in order to improve the content of soil water stable aggregate and organic carbon, and achieve healthy and balanced development of land reclamation and ecosystem in opencast mine.