Demarcating permanent basic farmland considering the ecosystem connectivity

In the context of ecological civilization, it is of great significance to explore the method of permanent basic farmland demarcate that takes into account the protection of arable land resources and the maintenance of ecosystems in order to build a new pattern of spatial development of the national territory.The study has been constructed a set of permanent basic farmland demarcate method considering ecosystem connectivity by combining land evaluation and site assessment method and future land use simulation model on the basis of identifying ecological sources, ecological corridors and "stepping stone" through the model of minimum cumulative resistance model and circuit theory, In order to provide some theoretical references for the demarcate of permanent basic farmland in Shiyan City. The results show: 1) Shiyan City has a total of 26 ecological sources, mainly forests and waters, distributed in the southern and central hilly areas; a total of 66 ecological corridors, centrally located in the territory of Zhuxi County, Zhushan County, Fang County, etc.; and a total of 121 "stepping stones". 2) According to the comprehensive evaluation score of land evalution and site assessment and the permanent basic farmland demand target of Shiyan City, the arable land with a comprehensive score ≥48.68 will be designated as permanent basic farmland, and the final area of permanent basic farmland is 167 800.23 hm², which is mainly distributed in the southwestern part of Zhushan County, northern part of Zhuxi County, the central part of Fang County, and the central and northern part of Danjiangkou City, etc. However, there are serious conflicts with the important ecosystem connectivity land, including 1 772.64 hm² with ecological sources, 4 274.19 hm² with ecological corridors, and 391.86 hm² with "stepping stones". 3) Based on the FLUS model to simulate the process of permanent basic farmland demarcate in Shiyan City, the demarcated area is 167800.05 hm², mainly located in the flat area of the river valley on the border of Zhushan County and Zhuxi County, the northern part of Danjiangkou City, the eastern part of Yunyang District, etc., with a high degree of centralization and contiguity; moreover, the demarcated permanent basic farmland effectively avoids encroachment on ecological source, ecological corridor and "stepping stone", realize the permanent basic farmland protection and ecosystem connectivity maintenance and coordinated development.4) Comparing the results of LESA with those of permanent basic farmland demarcate with consideration of ecosystem connectivity, it is found that permanent basic farmland demarcated based on the LESA method ignores the serious impact on ecosystem connectivity, while permanent basic farmland demarcated with consideration of ecosystem connectivity not only takes into account the impact on ecosystem connectivity, but also follows the historical pattern of urban expansion, realizing the harmonization of permanent basic farmland protection, ecosystem connectivity preservation and urban growth. In addition, the permanent basic farmland demarcated by the ecosystem connectivity approach is of higher quality, more concentrated and contiguous, and has a more regular shape, which is more conducive to mechanized farming, thus playing an important role in guaranteeing China's food security, advancing the structural reform of the agricultural supply side, and realizing the revitalization of the countryside.