Delimitating permanent prime farmland reserve areas on the perspective of suitability-cluster-stability

Abstract: Permanent prime farmland reserve areas have served as the direct supplementary sources of capital cultivated land. This type of high-quality cultivated land can widely be expected to extend for the ecological protection, and the sustainable "balance of occupation and supplement". Meanwhile, the reserve resources of cultivated land have been posed a great challenge on the occupation of new construction land, particularly with the recent acceleration of industrialization and urbanization. Therefore, it is very necessary to launch the spatial zoning of permanent prime farmland reserve areas, further to ensure national food security, quantity and quality stability of an optimal land pattern under an ecological protection for the high-quality cultivated lands. In this study, an evaluation system of permanent prime farmland reserve area was established from three dimensions of suitability, cluster and stability. Taking 2030 as the target year, a risk index of cultivated land conversion was also introduced to maximize the land use benefits. The policy requirements were firstly sorted to clarify the connotation of permanent prime farmland reserve areas. A FLUS model was then selected to estimate the land use structure under the multiple objectives of food security, economic development, and ecological protection. A conversion probability of cultivated land was also combined to predict the possibility of conversion of cultivated land to other land types, in order to achieve the stability of permanent prime farmland reserve areas during the conversion of cultivated land. A weighted superposition was conducted to evaluate the comprehensive quality of general cultivated land, where the permanent prime farmland reserve areas were classified, according to the evaluation. A three-dimensional Rubik's cube spatial classification was also selected to divide into some consolidation zones. As such, the Jintan District of Changzhou City of Jiangsu Province was taken as a case study. The results showed as follows. 1) Two types of delimitation criteria (constraint and evaluation) were conducive to the rational decision-making on the permanent prime farmlands. 2) The comprehensive quality score of general cultivated land in the study area ranged from 35.52-100, with an average score of 67.76, which was generally at a relatively high level. A large number of cultivated lands with high comprehensive quality cannot be classified into the permanent prime farmland, where there was no protection. Therefore, it is highly urgent to protect the high-quality cultivated land by designating the permanent prime farmland reserve area. 3) A total of 7 465.58 hm2 permanent prime farmland reserve area was designated in the study area using the index evaluation of cultivated land suitability, cluster, and stability. 4) Four types of potential areas can also be divided into the comprehensive utilization, production improvement, development ascension, and the production improvement-development ascension, particularly with the comprehensive quality of cultivated land. Anyway, the finding can be beneficial to implement the regulatory measures for different types, further to improve the suitability, cluster and stability of permanent prime farmland.