ANALYSIS ABOUT THE KEY POINT OF ECO-ENVIRONMENT CONSTRUCTION ON LOESS PLATEAU
开发西部切入点的研究──以黄土高原生态环境建设切入点为例

The western development is an important strategy task in our country ,but it is limited by soil erosion and land desertification, so the key point to carry out the western development is defined by the preservation and construction of eco- environment. According to the occurrence and development of soil erosion process, the key point to carry out the eco-environment construction has been studied and analyzed further in the paper. The natural erosion changing into the accelerated erosion was also demonstrated since the geological and historical period, which revealed that the contradiction in human-land system caused by the destruction forest and grass land and unteasonable reclamation is the main cause of aggravating soil erosion and worse eco-environment. Based on plenties of data by field investigation and dynamic observation, the damage of soil erosion from slope farmland was analyzed, including the change of soil erosion types and erosion intensity, the increase of river sediment the landform evolution, the soil quality degeneration and the ecio-environment deterioration. It was showed that to control soil erosion of slope farmland is the main problem of soil conservation and to return slope farmand into forest and grass land is the key point to carry out the eco-environment construction. The key point to return slope farmland into forest and grass land was analyzed in the paper, which should integrate with the erosion environment instigation. The suitable slope degree to withdraw slope farmland in the different districts was studied further. To strengthen study on the vegetation evolution and reconstruction, the mechanism of dynamic balance of energy flow and matter cycle between vegetation and its living environment was proposed.