中文摘要：

基于GIS空间分析技术,利用数字地形高程图生成地形高程和坡度分级图,将地形高程分级图、地形坡度分级图、2000年耕地分布图和分县行政区划图叠加,提取2000年分县耕地地形分异数据,计算2006年分县适垦耕地面积,以适垦耕地指数和人均适垦耕地面积为指标,分析我国适垦耕地的空间分异特征。结果表明：1）我国耕地的地形分异特点是随着地形高程和坡度的增加,耕地面积均呈现快速下降的趋势,耕地主要集中于海拔500 m以下且坡度较小的地域。2）适垦耕地的空间分异主要受地形条件控制,海拔较低、地形平缓的平原、盆地和河谷适垦耕地指数一般在50%以上,而海拔较高、地形起伏较大的高原、山地和丘陵地区指数值普遍低于30%。3）我国人均适垦耕地面积空间分布的总体特征是北多南少,人均适垦耕地面积在0.2 hm2以上的高类和较高类大都分布在北方地区,而人均适垦耕地面积在0.067 hm2以下的低类和较低类主要集中于青藏高原及东南沿海地区。

英文摘要：

Based on spatial analysis methods of GIS,the terrain elevation and gradient classification maps were produced by using digital terrain elevation map.And then,the terrain distribution data of the cultivated land of counties of 2000 was extracted and arable cultivated land area of counties of 2006 was calculated,by overlapping the terrain elevation classification map,terrain gradient classification map,cultivated land distribution map of 2000 and administrative division map of counties.Taking arable cultivated land index and per capita arable cultivated land area as indicators,the spatial differentiation of arable cultivated land in China was analyzed.As a result,this paper found：1） The terrain distribution characteristic of cultivated land in China was that the cultivated land area descends sharply with the increment of terrain elevation and gradient.Cultivated land was mainly distributed in the region where the altitude was below 500 meters and the slope gradient was under 3°.2） The spatial differentiation of arable cultivated land was mainly controlled by terrain condition.The arable cultivated land index usually exceeded 50% in plain,basin and river valley where the altitude was relatively low and the hypsography was mild.But the index value was generally below 30% in those plateau,mountainous land and hilly-gully regions where the altitude was relatively high and the hypsography was complicated.3） The whole characteristic of spatial distribution of per capita arable cultivated land area in China was that the value of the north of China was more than the south,the types of Higher and High where the per capita arable cultivated land area was above 0.2 hm2 mainly concentrated in the north of China,and the types of Lowest and Lower where the per capita arable cultivated land area was below 0.067 hm2 mostly located in the Qinghai-Tibet Plateau and the southeast coastal areas of China.