A GIS-based Study On Middle-scale Soil Spatial Distribution Pattern ---Taking Xi'an Area As An Example

Soil resource is the basis for human existence and sustainable development. The analysis of soil spatial distribution pattern is constantly an important research aspect in soil science. In this paper, the middle scale-soil spatial distribution pattern was studied. This project was supported by the national natural science foundation program named as The Middle-scale Soil Landscape Spatial Pattern Analysis.GIS spatial analysis methods, such as overlay, complex and cluster, buffer analysis, digital teirain analysis, and statistical analysis method were employed to the research on middle-scale soil distribution pattern and soil physical and chemical properties varying pattern. Experiments show all these factors have a close relationship with the terrain factors, such as elevation, aspect and distance from the river.In this paper, Xi'an area \\as taken as an example. DEMs, digital soil physical and chemical properties model including digital organic matter content model, digital PH value model, digital cation exchange capacity model and digital clay content model were established in Xi'an area. By means of DEM surface profile graph and isoline graph methods, several key analysis models are created, more graphes, such as soil organic matter content isoline graph, soil organic matter content surface profile graph, PH value surface profile graph, cation exchange capacity surface profile graph and clay content surface profile graph contribute a great deal in analyzing the relationship between physical & chemical properties and terrain variation.With GIS spatial analysis method, the spatial distribution information of soilphysical and chemical properties at different elevation, aspect and the distance fromthe river were derived, which can be used to the quantity analysis of soil physical andchemical properties spatial variation pattern. The study can be regarded as an innovation of GIS technique in the field of middle-scale soil physical and chemical properties pattern application GIS.Besides, soil database was established, which provides the perimeter, the area and the number of soil patch. Furthermore, soil homogeneous index and diversity index were counted by soil data according to landscape ecology and were also analysed statistically. The study was a beneficial research in soil landscape adopting geographic information science.The results of this research show that, the application of GIS method to soil science research is feasible. Xi'an area's soil possesses distinct spatial distribution pattern, for instance, soil distribution possesses obvious vertical zonization, soil physical and chemical properties have an obvious related variation with the terrain factors variation and soil patch homogenoeus are higher in the research region. The Statistical research method is of vital importance in the analysis of soil spatial distribution pattern. The study can be seen as a successful exploration in soil science and landscape ecology. More works will be encouraged in this field.