关键词: 西部地区开发, 退耕还林还草, 草业生态系统工程

Abstract: The suggestions on returning farmland to forests and grassland are listed here.1.The natural forests have seldom existed in the steppe,desert and frigid alpine regions due to the natural conditions of the bio-climatic zone.However in some non-climatic zone areas,Northward mountain slopes,valleys of some mountains,river shores and lakesides and the sandlands with more moisture,the forests do exist and trees could be planted.Such dialectical relationship between tree planting and bio-climatic zone is worth consideration.Moreover,the purpose of afforestation in the region,the conception of forestry,the structure of the forests and the tree species to be chosen must adjust to the arid or semiarid and the non-forest climat.The forestry andministration the scrubs and shrubbery groves with trees and forests.It could bring confusions to the conception of biology,ecology,forestry geography.2.Returning of farmland to grassland must be recognized as a brilliant start of our forage inducstry,which with grasses and animal husbandry,as its core combining feed production,eco-protective forestry,and intensive culture of useful endemic species of the steppe desert and alpine regions,form a holistic ecological and systematic project.Included in the forage industry systematic project are the vast natural grassland and the fenced and rotative grazing pastures,Grazing them is not an out dated pattern of grassland utilization,but a advanced accelerated biological nutrient cycling system,perticularly significant to China.

Key words: Development of the western regions, Farmlands returning to forests and grassland, Forage industry ecosystem project