Spatial And Temporal Variation Of Soil Nutrients And Environmental Interpretation Of Opencast Coal Mine Dump Area

The opencast coal mine dump destroyed and occupied a great of land resources, polluted the environment seriously, so it is important to have ecological rehabilitation in mined area. Vegetation restoration is the first choice of the restoring degraded ecosystem and improving soil fertility, and it is very effective and economic. Soil improvement results from the comprehensive effects such as climate, terrain and so on. Different platforms have different emission years, different vegetation coverage, different vegetation restoration years and different geography, so the improvement effects are different. Analysis of the soil and its relationships with environmental factors are important to grasp the dynamics driving force and choose the right variety of plant combinations. This paper based on the theory of geostatistics and biogeographic, mainly presents the relationship between soil and environmental factors in opencast coal mine dump area. The main works of this research are as follows:(1) Research on the spatial and temporal variation of soil in the dump. According to theory of geostatistics, included the regionalized variables, the semi-variance function and Kriging Interpolation, combining with the classical statistics theory and the platform of ArcGIS 9.3,This paper main study the spatial and temporal variation of the dump soil. The results show that contents of the elements have been improved. From the spatial distribution of soil nutrients, the OM, NH4_N, P and AK present the uneven distribution in the northeast than the southwest, which completely different from Ca, S, and pH. From the coefficient of variation, variation coefficient of OM, pH, S increased slightly, which shows that the spatial distributions of them tended to be inhomogenous, Other elements increased slightly, but not very much. The C0/(C+C0) of other nutrients were over 70% except pH, Ca ,which means spatial correlation of the soil nutrients were very weak.(2) Research on the relationships between soil nutrients and environmental factors. From the data analysis, different emission years caused different soil-forming parent materials. Emission years have positive correlation with the soil-forming parent material. Other things being equal, Green bristlegrass+Robinia pseudoacacia+ Ulmus pumila in platforms of 4 and 5 grown best,which vegetation coverage reached 80%-90%,altitude were negative with soil nutrients. Similarly, Green bristlegrass+Robinia pseudoacacia are better for the soil recovery in the early period of restoration of the vegetation under the same conditions. By using the classification and sorting method in quantitative ecology, Canonical Correspondence Analysis(CCA)method. The results show that:the first axles of the ordination diagram makes the greatest contribution by up to 64.6%,Five factors have a certain extent effect on the soil properties and distribution, the influence degree in order is the emissions fixed number of year, Vegetation restoration fixed number of year, vegetation types, elevation, vegetation coverage. The soil elements evenly distributed around the midpoint, at the same time, they are closer to the vertical distance of the arrow which represent environment. But the OM, NH4-N are closer to the arrow which represent emissions fixed number of year, Vegetation restoration fixed number of year. So the connections between each other are better. The soil square samples are divided into four types using this method, corresponding four different vegetation combinations: Green bristlegrass+Bulrush+Cleistogenes spuarrosa,Green bristle grass+Mugwort+Ulmus pumila,Green bristlegrass+Robinia pseudoacacia,Bulrush+Green bristlegrass+False indigo,and the classification results are consistent with field investigation. The results show that Green bristlegrass+Robinia pseudoacacia are better for the soil recovery in the early period of restoration of the vegetation.