Study on Spatiotemporal Changes of Cultivated Land in the Major Grain-Producing Areas of the Middle and Lower Reaches of the Yangtze River

Cultivated land is the primary form of rural land use and a critical resource for human survival. Investigating the spatiotemporal variation characteristics of cultivated land resources holds profound significance for strengthening cultivated land protection and optimizing spatial distribution patterns. This study used land-use data from four periods (1990, 2000, 2010, and 2023) in the Major Grain Producing Areas of the Middle and Lower Reaches of the Yangtze River. Using a land-use transition matrix and a dynamic degree model of land use, we analyzed the spatiotemporal evolution of cultivated land resources in this region. The results indicate: (1) Cultivated land resources exhibited uneven spatial distribution, with higher concentrations in the northeastern regions and lower densities in the southwestern areas. Between 1990 and 2023, except for Jiangxi Province, which experienced an increase of 454.32 km² in cultivated land area, all other provinces demonstrated decreasing trends. Specifically, Jiangsu, Anhui, Hubei, and Hunan provinces recorded reductions of 12,895.67 km², 8,207.89 km², 2,797.64 km², and 958.44 km², respectively. (2) Regarding the dynamics of cultivated land changes: From 1990 to 2000, while Hubei Province showed expansion tendencies, other provinces experienced contraction; between 2000 and 2010, Hunan Province underwent significant expansion while Jiangsu Province faced substantial reduction, with other provinces maintaining contraction trends; during 2010–2023, apart from dramatic expansion in Jiangxi Province, other provinces exhibited minor reduction tendencies. (3) Throughout the study period, significant conversions occurred between cultivated land and other land-use types. Cultivated land was primarily converted to forests and impervious surfaces, while newly added cultivated land mainly originated from forest conversion. Over the 33 years, the total cultivated land area in the study region decreased by 24,405.31 km².