Models of vegetation and soil coupling coordinative degree in grain for green project in depressions between karst hills

Coupling coordinative relationship of vegetation and soil is the key for ecological restoration and for implementing grain for green project. Based on the investigation and analysis of vegetation and soil in seven grain for green patterns in depressions between karst hills, a two-level target system of nine vegetation factors and fifteen soil factors was conducted, and the weight of factors was determined by step weight analysis and models of vegetation and soil coupling degree and coupling coordinative degree were constructed. The results showed that the relationships of coupling degree and coupling coordinative degree of grain for green patterns were not one-to-one correspondence in the region, and the integrative indexes of vegetation in the patterns didn’t quite fit with those of soil. The vegetation effects of Zenia insignis + Guimu No. 1 Forage pattern and the soil improvement effects of Toona sinensis pattern were best in these patterns. The status of vegetation and soil coupling coordination in the patterns after 5 years’ was still not ideal, as except for patterns of Toona sinensis and deserting cultivation were in the stage of middle level coordinative development, and other patterns were in the stages of deterioration caused by disorders or overdevelopment. Only the models of vegetation and soil coupling coordinative degree for patterns of Guimu No. 1 Forage and deserting cultivation were in synchronization. Therefore, improvement of vegetation growth and soil management should be done during the application of grain for green project in depressions between karst hills.