Spatial-temporal characteristics of cropland distribution and its landscape fragmentation in China

Analysing China's cropland changes highlights the intertwined dynamics of urbanization, industrialization, and ecological policies, offering insights into cropland efficiency and advancing agricultural modernization. This study analysed China's county-level cropland area and landscape fragmentation from 1990 to 2021 using land use data. The results revealed an uneven cropland distribution in China, which was mainly concentrated in regions such as Northeast China, the North China Plain, the Sichuan Basin, and the Middle-Lower Yangtze Plains, with most cropland occurring north of the Qinling Mountains-Huaihe River boundary. In the past three decades, China's cropland area has decreased by 8.68 million ha. Approximately 72.14% of the counties experienced a decline, and 24 provinces reported a net loss. Notably, there was large-scale land use type replacement in China, which was primarily manifested as the spatial displacement of cropland with forest, grassland, and impervious surfaces. As a result, the net reduction in cropland accounted for only 22.24% of the total cropland decrease. From 1990 to 2021, 52.04% of China's county-level cropland exhibited no significant changes in total area (TA) or patch density (PD), maintaining a stable cropland landscape. A total of 20.70% of the counties had significant TA reductions without PD changes, primarily in the Huang-Huai-Hai Plain. Counties without TA changes but significant PD declines represented 11.72%, mainly distributed in transitional zones of the second and third steps of China's terrain, the Loess Plateau, the Yunnan-Guizhou Plateau, and some areas of the Southeast Hills. Counties with significant TA reductions and PD increases accounted for 7.79%, primarily found in the border areas between Henan and Anhui, as well as Jiangsu. Thus, whether cropland loss in China over the past 30 years has led to increased fragmentation has shown clear spatial heterogeneity. This study provides scientific support for guiding cropland utilization to enhance sustainability and resilience in China.