Farmland transition and its influences on grain production in China

Land use transitions and socio-economic transitions jointly drive urban-rural transformation development in China. Farmland resources are a core element contributing to food security, and the characteristics of farmland transition and its influences on grain production in the urban-rural transformation development process help reveal the underlying laws governing farmland transition. Farmland transition characteristics also help effectively regulate grain production transition in China. Given the "man-land relationship" defined by large populations with relatively little arable land in China, this paper constructs a theoretical model for farmland transition using the per capita farmland area (PCFA) metric, which consists of the temporal changes in PCFA and PCFA spatial transitions as elevations change. Based on the theoretical model for farmland transition, we designed a coupling coefficient between PCFA and per capita grain possession, uncovering the inner link between farmland transition and grain production transition in China. Based on transitions measured at a 1 km gridded resolution of PCFA across the country, this study found that China's PCFA transitioned from a gradual decline to a steady rise during 1990-2010. In addition, the spatial transition trends for farmland were significant. The elevations of 1000 m and 500 m marked two important lines in the spatial transition of farmland, representing inflection points for the PCFA change trend and PCFA growth rate, respectively. The study concludes that regional differences in grain production transition are significant in the farmland transition process. While traditional agricultural areas gradually transitioned from an "Intensive type" to a "Modern type," grain production in South China experienced a significant "Declining type" transition trend. Regulating the farmland transition process can provide a basis for decision making about appropriate grain production scales of farmers in China. Farmland transition and urban-rural transformation development are closely related; as such, properly coordinating the relationship between them can help stabilize the socio-economic transition in China.