黄土高原地区的可能退耕规模及其减产效应

退耕还林还草工程是黄土高原地区水土保持和生态环境建设的重大举措。如何在水土保持和生态建设过程中保障粮食自给，是恢复全区生态环境和社会经济发展的关键。该文根据土地利用详查与实地调查资料，利用多目标规划模型与退耕压力指数模型，定量分析了黄土高原地区退耕的可能规模及其粮食减产效应。研究认为：在保证人均耕地0.1 hm²前提下，黄土高原地区退耕面积可达236.46×10⁴ hm²，占现有耕地的1/5强；对应的粮食减产量为195.26×10⁴t，是1996—2000年平均粮食产量的12.69%；全区基于人均粮食占有量的退耕压力指数达0.20，晋陕甘黄土丘陵沟壑台塬区是退耕压力最大的区域。

The Scale of Land Conversion and Its Effect on the Grain Production in Loess Plateau Area

The conversion of cultivated land back into forest or pasture is an important campaign to improve the ecosystem and protect the environment in the Loess Plateau,but the key is how to improve grain productivity in the remaining arable land and ensure the grain self-sufficiency in the process of ecosystem construction and water conservation,which concerns the ecological environment recovery and socioeconomic development of the area.Based on land use statistics and on-spot survey data,and using the models of target programming and pressure index,the paper analyzes the possible scale of converting cultivated land back into forest or pasture and its pressure on Loess Plateau,suggesting that when 01 hm² per capita cultivated land is ensured,the farmland converted on the slopes above 15 degrees will be 236.46×10⁴　hm²,meaning a little over a fifth of the present area of the arable land,that the corresponding reduction of grain will be 195.26×10⁴　t，accounting for 12.69% of average annual grain production from 1996 to 2000,and that the pressure index based on per capita grain possession will be 0.20 for the whole area,making the Loess Plateau Area in Shanxi,Shaanxi,and Gansu Provinces the most heavily impacted area by the conversion.