Delineation of a permanent basic farmland protection area around a city centre: Case study of Changzhou City, China

- We constructed a systematic classification model of farmland.
- Farmland contiguity was analyzed from pixel scale.
- We developed an evaluation model for comprehensive farmland productivity.
- A model was proposed to delineate permanent basic farmland for plain areas in China.

The delineation of permanent basic farmland will safeguard the production baseline of China's agricultural development by securing easily appropriated, high-quality farmland surrounding urban areas, thereby strictly controlling the use of farmland (especially high-quality farmland surrounding urban areas) facing accelerated urban expansion. This study researched the delineation of permanent basic farmland in a typical region undergoing rapid urbanization. By constructing a systematic classification model, farmland was classified into matrix, edge, and island farmlands in order to analyze farmland contiguity and fragmentation. Based on the indicator requirements of various plans related to farmland, an evaluation indicator system was constructed in order to develop an evaluation model for comprehensive farmland productivity. From the perspective of farmland spatial contiguity and highly efficient productivity, a delineation model for permanent basic farmland was proposed to delimit the permanent protection and utilization boundaries for high-quality farmland around urban areas. The results show the following: (1) matrix and edge farmlands can intuitively display farmland contiguity characteristics; (2) comprehensive farmland productivity was closely related to farmland spatial patterns, supporting infrastructure, and policy management and protection; and (3) there was a high degree of spatial overlap between contiguous and highly productive farmland. The model took both comprehensive farmland productivity and spatial clustering into consideration in order to delineate permanent basic farmland, which is a beneficial factor in protecting farmland quality and safeguarding sustainable farmland utilization. It can also be used as a control line to limit urban sprawl, guide urban cluster development, and improve economical and intensive urban land use.