STUDY ON EXCHANGING TREE AND GRASS WITH GRAIN AND SUSTAINABLE DEVELOPMENT IN HEXI REGION——TAKING WUWEI PREFECTURE AS A CASE
以甘肃武威地区为例，分析石羊河流域因贫困、经济利益驱动和管理不善导致的森林破坏、荒漠化等问题，探讨国家通过粮食和补贴鼓励农民退耕还林还草以促进生态重建和可持续发展的必要性及待研究的问题。
Shiyanghe, an inland river, locates in eastern Hexi region of Gansu Province. Wuwei Prefecture mainly consists ofShiyanghe valley. The water from Qilianshan, which is upper reach of Shiyanghe valley, bred glorious Wuwei oasis culture. However, for reasons of poverty, motivation of high economic benefit and weak management, the water-beating forest andsoil-preserving forest in Qilianshan were destroyed heavily in the past. Some turned into cultivated land while others becamebald. The water-bearing function of forest decayed and sand content of rivers increased. Meanwhile, with increase in irrigationarea of upper and middle reaches, the water flowing to lower reach becomes less and less, which causes large-scale utilizationof underground water. A great deal of sand vegetation died for less and less ground water and deeper and deeper underground wa-ter. Desertification and salinization trouble the lower reach. The ecological rebuilding is confined by poverty, low economic benefits of peasants and population pressure, etc. In thiscase, the method of providing grain and subsidy by national government for peasants to replant tree and grass in slope land isnecessary for Wuwei Prefecture to rebuild ecological environment and promote sustainable development. Such things as peasants'willingness, relatively economic benefit and methods of organization and management are needed further study. The method ofexchanging tree and grass with grain may not resolve all problems. To restore ecological balance and realize sustainable develop-ment, efforts of all sides and from all channels are hoped.