Optimization of the spatial layout of farmland from the perspective of multi-scale administrative balance

The optimal spatial layout of farmland is of great significance in improving the production capacity. The agricultural and geographical patterns can also be better matched for the national food security. However, the previous researches focus mainly on the spatial layout at the scale of specific administrative districts. It is still lacking in the replacement of farmland with the restored land. Taking Fengkai County in Guangdong Province as an example, this study aims to follow the micro adjustment on "transferring out existing farmland and transferring in restored land". Firstly, the spatial superposition and comprehensive evaluation methods were used to identify the farmland that transferred out with the fragmented, unstable and low production potential. Secondly, the screening utility function was constructed based on the three objectives of the maximization of agricultural production suitability, the minimization of the importance of ecosystem service functions, and the maximization of layout compactness of the restored land. An optimal model was also constructed to adjust the spatial layout of farmland, according to the two aspects of transferring in and out. Taking the balance of the number of transfers in and out as a constraint, the spatial layout of farmland was optimized at different administrative scales. The results showed that: 1) A total of 1,689.89 hm² of farmland was transferred out of the study area, accounting for 7.62% of the total area of farmland. The overall distribution of farmland was characterized by "global fragmentation and local aggregation". 2) The average suitability of agricultural production and integrated ecosystem services in the restored land were 67.04 and 40.52, respectively, indicating the superior resource endowment in agricultural and ecological production. 3) There were significant differences in farmland that transferred in at administrative scales. The average suitability of agricultural production increased by 2.08 in the farmland that transferred in, whereas, the mean value of comprehensive ecosystem services decreased by 0.67 in the intra-county balance scenario, compared with the intra-town one. The screening of farmland that transferred in was more effective at a wider spatial scale. 4) The quality, stability, and contiguity of optimal farmlands were improved in both scenarios. The optimization was much more outstanding in the intra-county balance scenario, compared with the intra-town one. There were also significant impacts on the administrative scales. An optimal expansion in the screening scale of restored land can be expected to improve the overall quality of farmland and reduce the probability of screening ecologically important land. There were two contributions of this study. Firstly, an optimal model was constructed on the spatial layout with better applicability. The dynamic adjustment was realized to optimize the current farmland and the restored land. Secondly, there were some differences in the spatial layout of farmland at the scale of administrative regions. The administrative regions can be considered to formulate the policies for farmland protection. The finding can provide a strong reference for the decision-making on the optimization of spatial layout of restored land and farmland.