权衡耕地保护与城市扩张的永久基本农田划定--以武汉市为例

Demarcating of Permanent Prime Farmland for Synergy of Farmland Protection and Urban Expansion: A Case Study of Wuhan

永久基本农田划定是实现耕地保护、土地集约利用以及保障粮食安全的有效方式。然而城市的快速扩张给永久基本农田划定带来了挑战,如何协调城市扩张与耕地保护两者的关系、科学合理地划定永久基本农田亟待解决。本文以武汉市为例,结合LESA(Land Evaluation and Site Assessment)方法及LANDSCAPE模型(LAND System Cellular Automata Model for Potential Effects)综合考虑永久基本农田划定与城市扩张的冲突,进行永久基本农田划定,试图协调耕地保护与城市扩张对土地资源需求的矛盾,为"多规合一"背景下科学划定永久基本农田提供方法借鉴,为优质耕地保护及土地利用优化布局提供决策参考。①运用LESA方法对武汉市的耕地进行综合质量评价及等级划分;②基于LESA综合评价结果,运用LANDSCAPE模型对武汉市永久基本农田划定及城镇建设用地扩张进行模拟;③将LANDSCAPE模型划定的永久基本农田结果与基于LESA方法划定的结果进行数量、质量和空间形态上的对比分析。结果表明:2种方法划定的永久基本农田面积相当,质量差异不大。但在空间形态上,基于LANDSCAPE模型的划定结果明显优于基于LESA方法:划定的永久基本农田集中连片分布,形状较为规则。值得注意的是,LESA方法划定的永久基本农田中有15.8%将被新增城镇建设用地侵占,而LANDSCAPE模型能够有效避免这部分永久基本农田被侵占。

Demarcating permanent prime farmland is an effective way to realize farmland protection, intensive land use and food security. With the challenging of rapid urban expansion, the completion between urban expansion and farmland protection is unavoidable. It is urgent to reasonably demarcating permanent prime farmland by synergizing farmland protection and urban expansion. In view of this conflict, taking Wuhan as an example, this paper carries out the demarcation of permanent prime farmland by using LESA(Land Evaluation and Site Assessment) method and LANDSCAPE( LAND System Cellular Automata model for Potential Effects)model, attempting to achieve balanced development of urban expansion and farmland protection, which provides reference for scientific demarcation of permanent prime farmland under the background of multiplanning integration, and provides support for prime farmland protection and optimizing of land allocation. Firstly,comprehensive evaluation and classification of farmland in Wuhan is carried out through LESA, then based on this result, simulation of demarcation of permanent prime farmland and urban expansion is carried out through LANDSCAPE model, at last, the results of the two methods are compared in quantity, quality and spatial patterns. The results show that permanent prime farmlands demarcated in two methods have little difference in quantity and quality. The area of permanent prime farmland demarcated by LESA method is 243 259 hm2,45.63% of which land fertility grade of cultivated land is between grade 1 and grade 3. The area of permanent prime farmland demarcated by LANDSCAPE model is 243 200 hm2, 45.77% of which land fertility grade of cultivated land is between grade 1 and grade 3. There are more than 80% of the permanent prime farmland that land fertility grade is between grade 1 and grade 5 in both methods, which shows that the total quality of permanent prime farmland is good in either method. However, the result of LANDSCAPE model is better in spatial patterns, which permanent prime farmland demarcated by LANDSCAPE model distributes concentrated and is regular in shape. It’s remarkable that 15.8% of permanent prime farmlands demarcated by LESA are overlapped by urban constructive land in the processing of urban expansion, which has been effectively avoided by LANDSCAPE model. The possible cause of this conflict are as follows:(1) The permanent prime farmland demarcated by LESA method is based on ranking of integrated score, in which the requirements for concentrated fragmentation and shape index of permanent prime farmland are not considered;(2) The conflict of farmland protection and urban expansion is not considered in LESA method.