三区三线统筹划定中永久基本农田布局优化方法与实证

科学统筹划定"三区三线"，是落实主体功能区战略、构建国土空间开发保护新格局的重要举措。针对"三区三线"底版不统一、边界不一致、存在交叉冲突等问题，提出了基于"三区三线"统筹和第三次全国国土调查成果的永久基本农田布局优化技术路线及布局优化原则，构建了永久基本农田生产-生态-景观综合评价指标体系，并在吉林省梅河口市进行了验证。结果表明：1）梅河口市永久基本农田优化后面积为91 680.82 hm2，增加1 290.69 hm2；质量等别为10级的耕地面积增加3 523.99 hm2、12级耕地面积减少2 324.85 hm2；耕地连片度提高，平均图斑面积由1.91 hm2增至2.61 hm2。优化后永久基本农田面积增加、质量提升、布局相对稳定。2）生态保护红线内的20.74 hm2永久基本农田以"开天窗"形式保留，城镇开发边界内的永久基本农田划出1 388.47 hm2（主要为零星破碎、生态质量较差、不稳定的永久基本农田图斑），对仍在城镇开发边界内的优质永久基本农田，以"开天窗"的形式保留，使三条控制线无交叉无重叠。3） 构建的永久基本农田生产-生态-景观综合评价指标体系，将水环境风险指标作为生态功能评价二级指标，考虑了农业面源对水环境的污染风险，兼顾农田生态系统的生态调节和保护功能。该方法充分体现了保障粮食安全、保护生态环境、兼顾城市发展思路，农业、生态、城镇空间布局得到统筹优化，可为新形势下科学开展"三区三线"统筹及国土空间规划编制提供方法借鉴。

Optimization method and empirical study on the layout of permanent basic farmland in the overall delimitation of "three land spaces and three control lines"

Abstract: A national scheme of "Three land spaces and three control lines" has been one of the most important strategies for land spatial planning and land policy in China. It is a high demand to delimitate the boundaries, and then implement the strategy of functional zones, particularly for the new pattern in the territorial space. In this study, a technical route and optimization principles were proposed for the permanent basic farmland layout using the overall delimitation of the "three land spaces and three control lines". The "three land spaces and three control lines" were also efficiently delineated, in order to deal with the disunity of the base map, inconsistency, and crossing of the boundary. The Third National Land Resource Survey data and the production-ecology-landscape indicators of comprehensive quality evaluation were constructed for the permanent basic farmland. Specifically, the comprehensive quality evaluation indicators were selected using the production condition, ecological condition, and location condition of cultivated land, which were the three primary indicators. Each primary indicator included several secondary indicators, including cropland quality, planting suitability, ecological protection importance, ecological regionalization, water environment risk, and cropland contiguity. Each indicator was assigned as several classification threshold values and weights, in order to evaluate and score the cultivated land parcal. More importantly, the water environment risk was selected as the indicator, considering the risk of water pollution from the non-point source of cultivated land. A case study was finally selected in Meihekou City, Jilin Province, China. The results showed that: 1) The specific area of optimized permanent basic farmland was 91 680.82 hm2 with an increase of 1 290.69 hm2. The area of cultivated land quality at level 10 increased by 3 523.99 hm2, and that of level 12 decreased by 2 324.85 hm2. The average area of permanent basic farmland patches increased from 1.91 hm2 to 2.61 hm2. The area and quality of permanent basic farmland were improved after optimization, indicating a much more stable layout in the study area. 2) Among them, the permanent basic farmland of 20.74 hm2 remained within the ecological red lines as the permanent basic farmland. In addition, the overlapped area was deleted from the ecological red lines. There was also the permanent basic farmland of 1 388.47 hm2 within the urban development boundary, which was removed from the permanent basic farmland, due to its low quality. The high-quality permanent basic farmland was still reserved within the urban development boundary, whereas, the overlapped area was removed from the urban development boundary, indicating the spatially consistent three lines. Food security, ecological protection, and urban development were considered in this case. The spatial layout of agriculture, ecology, and town space was optimized with coordination. The finding can provide a strong reference for the decision-making on the "three land spaces and three control lines" and land spatial planning.