1998年～2006年中国耕地资源的时空变化特征

Spatiotemporal Changes in Cultivated Land Area in China from 1998 to 2006

根据1998年～2006年全国土地利用变更和全国耕地变化情况数据，对中国耕地资源的时空变化特征进行了分析。研究表明：①1998年～2006年间，耕地资源结构变化的区域分异明显。黄淮海平原、长江中下游平原以及东部和东南沿海这些水热条件好、优质耕地集中的区域，灌溉耕地面积减少，耕地生产力降低；②除新疆和黑龙江耕地面积净增加外，全国其它地区耕地面积均呈下降趋势。耕地变化最为剧烈的地区分布在京津塘、长江三角洲、珠江三角洲的经济快速发展区和内蒙长城沿线农牧交错带；③耕地资源增减分布的区域差异明显。耕地减少区域主要分布在黄土高原区、内蒙古及长城沿线的农牧交错带区和东部水热条件较好的平原及丘陵区；耕地增加区域呈明显的西移趋势，由此而导致耕地的整体生态条件恶化；④耕地增减变化的原因亦存在区域差异。在黄土高原区和内蒙古及长城沿线的农牧交错区，耕地减少的主要原因是生态退耕；在经济发达的东部沿海区，耕地减少的主要原因是农业结构调整和建设用地扩张。对于新增耕地而言，在西部地区，主要来自土地开发；在中东部地区，主要来自土地开发和整理；⑤建设用地占用耕地主要是由于独立工矿和村庄的扩张，其区位分布恰和我国重要的粮食生产区域相重叠。

We used provincial data on current land use and conversion between different land types during 1998 - 2006 to analyze the spatiotemporal changes in cultivated land in China. The results showed distinct changes in the spatial structure of cultivated land, with declining conditions in the Huang-Huai-Hai Plain, the Yangtze River Plain, and the southeastern coastal region of China. There were 20 provinces which experienced a reduction in irrigated cultivated land, and six of these lost more than 7 % of total irrigated area. Cultivated land area decreased linearly from 1998 in all provinces except Xinjiang and Heilongjiang, with the most area lost in Inner Mongolia. The most notable changes were in regions that experienced rapid economic growth, including the Beijing-Tianjin-Tangshan region, the Yangtze River Delta and the Pearl River Delta. The mixed agro-pastoral zone on the Inner Mongolian plateau and areas along the Great Wall also exhibited strong changes. There was significant regional variation in the increase and decrease of cultivated land area. Cultivated land was reduced mainly in the Loess Plateau, Inner Mongolian plateau, along the Great Wall, and in the eastern regions. Increases in cultivated land occurred mainly in western China, causing environmental degradation. The reasons for changes in cultivated land area also varied. In the Loess Plateau, Inner Mongolia plateau, and the area along the Great Wall, reduction was due to government programs to reduce environmental degradation. In the developed eastern coastal regions, the reduction of cropland was mainly due to adjustment of agricultural structure and use of cultivated land for construction. In the western regions, the reason for increased cultivation was land exploitation, while in the eastern regions, the reasons for the increase were land exploitation and land consolidation. Building on previous farmland occurred mainly due to independent mining and expansion of villages, which occurred in the important national grain production regions. All of these factors led to an overall reduction in the quality of cultivated land and environmental degradation, which threatens China＇ s food security. Therefore, it is necessary to strengthen the intensive use of land resources and achieve a dynamic balance of cultivated land quantity and quality using protective measures such as limits on the use of cropland for construction, as well as strict controls on the unchecked expansion of large and medium-sized cities, strengthened rural planning, and protection of fertile cultivated land.