| As a result of special geographical position and wicked environment, the Western China became the main region which environment conditions need to be improved. At the same time, unreasonable using and extensive management to sloping plantation resulted in soil degenerating, output of food supplies being low and unsteady, regional environment becoming worse and worse. Under these circumstance, the State government put forward bringing the engineering of converting farmland to forest into effect. The engineering was fundamentality of the west region development. It was beneficial to adjust the country economic structure and promote boorish enrichment. Moreover, it may improve local climate of the Western China. However, there were not ready-made theory, technique, model and corresponding criterion of appraising benefit. After converting farmland to forest, how to increase boorish earning and keep the engineering stabilization for a long time, how to develop latter industry so as to bring into play the benefit adequately were the key and difficult problems of converting farmland to forest.On the basis of investigate the using and management of sloping farmland, this paper integrated and constituted existent research production of improving ecological environment and controlling loss of water and soil. Moreover, based on the ecological economics and restoration ecology, it established the experimentation exemplary areas to long systemic local-oriented observation. Through systemic study, the results were as follows:1. Comparing the foreign and Chinese current situation of converting farmland to forest, the results showed that the common ground was improving the quality of ecological environment and enhancing the ecological benefit. The tenets of converting farmland to forest in China were to not only maintain the ecological balance and improve the environment quality, but also solve boorish living problems. Its main purposes were to prevent loss of water and soil, control the desertification, reduce the frequency and degree of nature disaster. But the foreign purposes were to protect biology diversity, to prevent loss of water and soil, to rebuild the landscape and these were touch with significant problems, such as the global climate change, soil using change, etc.. On the other hand, the foreign engineering of converting farmland to forest all did not form so large scale as ours, and the farmer quantity were far from ours. Meanwhile, comparing other country, the engineering of converting farmland to forest in China still had special characteristics, for example, imperative disposal measures for ecology deterioration, timely change for policy of soil management, etc..2. The important factor of causing soil erosion was grade. The gradient critical value in soil erosion in Loess Plateau was 15~20 , and it in other regions was 25-30 . If the gradient was more than 25 , it was unable to produce the safety problems in food supplies after converting farmland to forest. If reducing the grade, it would be have some conflicts between food supplies and plantation. Because of unreasonable using and own characters, steep sloping field was ranged to agriculture ecosystem. Its character mainly include systemic structure being too simple, systemic productivity reducing, soil degeneration and nutrient decline,systemic function degeneration.3. The concept meaning and main character of converting farmland to forest were discussed. Its meaning was an special engineering which based on different natural economic and social conditions and beneficial forests' efficiency, integrated and constituted existent research production, and planted the forest in steep sloping field. This engineering was on the basis of ecological benefits and its core was economic benefits and its final aim was social sustainable development. Converting farmland to forest had natural, economic social and integrative characters.4.The converting farmland to forest engineering was some subjects' integration. And in course of formation and...
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