东北地区坡耕地空间分布及其对水土保持的启示

Spatial Distribution of Sloping Croplands in Northeast China and Its Implication on Soil and Water Conservation

土壤侵蚀正损害着东北地区的坡耕地,威胁国家粮食安全。然而,目前对东北地区坡耕地的宏观认识还很有限。该文利用高精度的空间数据,查明了整个东北地区及其各地貌分区、土壤类型、流域和行政区中坡耕地的面积和坡度特征。在此基础上,定量评估了治理工作的重要性,并在措施选择、治理工作布局等方面提供了建议。结果表明:(1)东北地区坡耕地的面积大、坡度小。总面积达到19.5万km2,平均坡度为3.4°。东北地区坡耕地面积占全国耕地总面积的14%,治理工作具有重要意义。(2)等高沟垅种植适用于全区大部分坡耕地。与之相关的技术手段、配套措施和管理制度应该被重视。>15°的坡耕地和风沙土等土壤类型中的坡耕地,产粮贡献小,侵蚀危险度高,应及早退耕。长白山地和暗棕壤区既是治理的重点地区,也是治理的难点地区,应被更多重视。(3)各县坡耕地治理的任务量和难度差异很大,且不宜使用县陆地面积和县耕地面积来评估。

Soil erosion is causing damage to the sloping croplands of northeast China and threatening the food security of China.However,little is known about them at macro scale.This study aims to investigate the area and slope gradient in different geomorphologic regions,soil types,watersheds and administrative divisions of the northeast region in order to guide the implementation of conservation management practices.The results indicate that:(1)sloping cropland of northeast China is characterized by large area with gentle slope gradients,the total area is about 195 000 km^2,with a mean slope of 3.4 degrees,the total area is about 195 000 km^2,with a mean slope of 3.4 degrees,the total area of sloping cropland of northeast China is about 14% of the total cropland area of China;therefore,management of these sloping croplands is important;(2)contour farming is suitable to most of the sloping croplands;Therefore,technologies,conservation practices and management systems related to sloping cropland deserve more attention;sloping croplands steeper than 15 degree,those located in the aeolian sandy soil,and some other soil types contribute little to grain production and exhibit a high erosion hazard,therefore,these croplands should be reused for the other purposes;the Changbaishan mountainous region and the dark-brown earth region are the key regions and difficult regions of management,and more attention should be paid to these regions;(3)the work load and difficulty of conservation management vary widely among counties,therefore,each county should be dealt with on its individual merits and not by the macroscale management decisions across counties,the load and difficulty of the management work of each county should not be evaluated by land area and cropland area.