中文摘要：

该文利用遥感与地理信息系统技术研究北京平原区农用地内部粮田、菜地和林地三大类农地利用类型的变化。结果表明：2004年至2014年这10 a间,粮田转变为林地与菜地是北京平原区农地利用变化主流。粮田转变为林地面积是969.97 km2,其土地利用变化重要性指数高达72.11%,在各类农地利用变化类型中居首。而粮田转为菜地则主要是粮田转变为设施菜地,10 a间粮田转变为设施菜地面积是163.53 km2,其土地利用变化重要性指数为12.16%,在各类农地利用变化类型中居次;同时,10 a间北京平原区农地利用变化存在空间分异特征。主城近郊区与远郊平原区农地利用变化主要是粮田转为林地,两大分区中该变化类型土地利用变化重要性指数分别为84.18%、76.21%,明显高于其他农地利用变化类型土地利用变化重要性指数。在城市新区,粮田则分别转为林地与设施菜地;10 a间北京平原区农地利用空间分布均具有圈层特征,由近郊向远郊,农地内部结构都呈现林地为主类型,到粮田、菜地与林地混合利用类型,再到粮田与林地组合利用类型的空间格局。而10 a间随着主城区的外扩,上述农地利用圈层特征出现了由近郊向远郊外移、且林地与蔬菜面积占比增加的现象。研究认为：农地内部粮、菜、林3地类的转变和农地利用圈层外移是农户追求经济效益最大化与政府为改善生态环境所致;而改善生态不应以牺牲粮田为代价,应充分利用粮田的生态系统服务功能以实现生态绿化目的。

英文摘要：

This research used the techniques of the remote sensing （RS） and geographic information system （GIS） to obtain the data of agricultural land use classifications by analyzing and interpreting the multi-spectrum remote sensing images, which were extracted from Landsat TM image in 2004 and Landsat OLI image in 2014. According to the situation of agricultural land use in Beijing plain, the agricultural land use were classified as the grain crop fields, vegetables cultivated in greenhouse, vegetables cultivated in the open fields and forest land. Then it analyzed spatial-temporal change characteristics of the agricultural land use in Beijing plain over the past decade （2004 to 2014） by combination of the quantitative geography model and geographic information system （GIS）. The results showed that the grain crop fields were changed into forest land and greenhouse vegetable fields, which was the major trend. The area of grain crop fields changed into forest land was 969.97 km2 whose land use change intensity index was 72.11%, at the top of all kinds of land use change intensity indexes. The area of grain crop fields changed into greenhouse vegetable fields was 163.53 km2 during the past 10 years, whose land use change intensity index was 12.16%, and ranked at the second among all kinds of land use change intensity indexes. Meanwhile the agricultural land use change had spatial characteristic in Beijing plain over the past 10 years. The leading type of agricultural land use changes was that grain crop fields turned into forest land in the suburban area and the distant suburb plain of Beijing, where land use change intensity indexes of grain crop fields into forest land were 84.18% and 76.21%, respectively and higher than the other agricultural land use change intensity indexes obviously. The overwhelming urbanization was encroaching upon a lot of grain crop fields, which leaded the agricultural land use to concentrate on the forest land in the suburban districts. At the same time grain crop fields changed