近几年来中国耕地占补的空间分异特征

Spatial Features of Occupation and Supplement Cropland Based on Topographic Factors in China from 2008-2010

地形是影响人类生产和生活的重要环境因子之一,也是影响土地资源结构及其变化的重要因素之一。本文基于全国地形数据和2008年-2010年土地利用动态变化数据,以占补耕地的海拔、坡度以及破碎度为主要参数,分析近年来中国占补耕地的地形分布特征。结果表明:①2008年-2010年,全国耕地占补呈现南占北补的空间分布格局,黑河-腾冲线以西以补充耕地为主,而黑河-腾冲线以东以占用耕地为主。其中新疆耕地补充较多,占全国补充耕地的76.8%,长三角、京津冀等地区耕地占用较为严重。甘肃、内蒙古、黑龙江等北方城市占用与补充耕地交错分布,在数量上基本达到占补耕地的动态平衡;②我国耕地重心向西北方向移动。耕地占用主要发生在华北、华中等地区,而补偿耕地主要在北方以及西北地区。从各省的情况看,产粮大省耕地占用较多,补偿不到位,且占用耕地地形要素较为优越,而补充耕地地形要素较差不利于农作物生长,如若不引起重视会对我国的粮食安全产生威胁;③从占补耕地的地形分布特征来说,全国38.7%的省份占用耕地的坡度小于全省耕地的平均坡度,而补偿耕地的平均坡度大于全省耕地的平均坡度,海拔、破碎度与耕地占补的关系也表现出与坡度类似的特征。这说明,我国在城市化加速的进程中,优质耕地资源存在被占用的情况,而在对耕地资源进行补偿的过程中,往往不能做到等质等量的耕地补偿,尤其是当占用了大量连片耕地时,补偿过程以零散地块补偿为主,大大削弱了耕地的生产能力,降低了耕地的规模化生产价值,增加了农业的投入产出比。

Terrain is one of the most important environmental factors affecting human life, production, land resource structure, and changes in these. Based on topographic data and land use dynamic change from 2008 to 2010 we analyzed China＇ s terrain features related to occupation and supplemental cropland using elevation, slope, and degree of fragmentation. We found a spatial distribution pattern of occupation cropland in southern China and supplemental cropland in northern China. The Heihe-Tengchong line still plays an important role, to the west of the line supplement cropland was more common than occupation cropland, while east of the line the opposite is true. Xinjiang had more supplemental cropland, accounting for 76.8% of the supplemental cropland in China. The occupation of cropland in the Yangtze River Delta, Beijing-Tianjin-Hebei and other areas is serious. Occupation and supplement cropland of Gansu, Inner Mongolia, Heilongjiang and other northern areas are interlaced in distribution and almost in dynamic balance. The barycenter of cropland moved northwest, from the view of China＇ s cropland dynamic change characteristics. China＇s cropland occupation occurred mainly in northern and central China, while supplemental cropland is mainly in northern and northwest China. Provinces that produced large quantities of food occupied more cropland, but supplement was not in place. The terrain elements of occupation cropland are of better quality, while terrain elements of supplement cropland are poorer quality and not conducive to the growth of crops. From topographical distribution characteristics of occupation-supplement cropland, the slope of occupation cropland is less than the average slope of the cropland across the province. The slope of supplemental cropland was above the average slope of the provincial cropland for 38.7% of provinces. Relationships among elevation, fragmentation degree and occupation-supplement cropland followed a similar pattern to that found for slope. China occupies a large number of high quality cropland resources in the process of accelerated urbanization, and cannot supplement the same amount and quality of cropland in the process of cropland compensation. Supplemental cropland occurs mainly as scattered plots and this greatly weakens the production capacity of cropland, reduces the large-scale production value of cropland, and increases the agricultural input-output ratio.