论文在1988～2000年全国土地利用矢量图的基础上,分析了城镇占用耕地的空间分布特征。利用城镇占用耕地指数将全国分县市占用剧烈程度进行分级,沿海及平原地区侵占剧烈程度为3～6级的占全国耕地损失的88.68%,华北平原、长江三角洲和珠江三角洲地区造成耕地损失分别占全国总数的31.27%、17.8%和6.02%,这3个地区是全国城镇扩展最快、耕地损失面积最大的地区。按地区分析,城镇占用耕地面积最大的是江苏、山东、河南、河北和广东,占全国的50.99%;其次是北京、浙江、四川、广西和上海,占全国的22.85%;从城镇造成耕地资源减少的速度看,北京、上海占用耕地最快,其次是江苏、广东、浙江、天津、山东、河北、海南等。耕地资源减少在某些地区已经造成了粮食产量减少的问题,北京、上海、浙江等地区粮食总产量降低较快。随着城镇化及经济的快速发展,城镇扩展与耕地资源的矛盾将会更加突出,只有加强土地资源的管理才能取得耕地资源的动态平衡和维护中国的粮食安全。

After the implementation of Reform and Open policy,the double-pressure of rapid economic development and population growth has imposed an unprecedented profound impact on Chinese dynamic change of land-use patterns.One of the most important problems is the urba-nization encroachment on cultivated land.China's per capita arable land is0.106ha,only making up44.9%of the world average.In the coastal area,a great amount of cultivated land was en-croached by urban expansion.Two-time TM images in1988and2000are used to monitor urban encroachment on cultivated land.The dynamic results revealed that of the land occupied due to urban expansion,80.2%is cultivated land and19.8%is forest land,grass land,rural area and other land.Index RI (Urban encroachment on cultivated land taken total land percent in the city and county)is built to study the regional difference.The cultivated land loss from grade3～6in coastal and plain area is about 88.68%while North China Plain is31.27%,Yangtze River delta17.8%and Pearl River delta is6.02%.The three parts witnessed the fastest urban expansion and cultivated land loss in China.The urban encroachment on cultivated land in Jiangsu,Shandong,Henan,Hebei and Guangdong takes about 50.99%and Beijing,Zhejiang,Sichuan,Guangxi,Shanghai takes22.85%.Except for Henan(located in North China Plain)and Sichuan(in Sichuan Basin),the others are coastal provinces.The cultivated land loss rate in Beijing and Shanghai is the fastest while that in Jiangsu,Guangdong,Zhejiang,Tianjin,Shandong,Hebei and Hainan comes second.With the rapid economic development and urbanization,the paradox between urban expansion and cultivated land will be more serious.Only more positive measures are taken to slow down the rate of cultivated land loss can the grain security be guaranteed.Firstly,the high-productive land should be protected.Secondly,high technology and machines should be applied to increase per unit area grain production.Thirdly,the rural residential land should be reclaimed with the local residents' immigration into cities and towns.