Uphill cropland and stability assessment of gained cropland in China over the preceding 30 years

In recent years, cropland development in high-slope regions in China has alleviated the contradiction between total cropland balance and insufficient development space. However, this change in cropland slope brings risks to sustainable resource utilization. This study explored the slope characteristics of cropland in China from 1990 to 2020 and assessed the gained cropland stability. The results showed that (1) From 1990 to 2020, the lost cropland area was greater than the gained area, and the distribution showed an uphill trend. (2) The areas with a significant upslope change in cropland were mainly concentrated in the southern plain, containing the central grain-producing regions at its core and other well-developed eastern coastal areas. (3) The areas with distinct downslope cropland changes were mainly concentrated in the upper reaches of the Yangtze and Yellow rivers and the ecologically fragile areas of Inner Mongolia and the Loess Plateau. (4) The gained cropland stability was unsatisfactory; about one-third of the gained cropland was unstable, which had the highest abandonment rate within 5 years, and the gained cropland stability decreased with the slope. In addition, this study explored cropland conversion types at different slopes in different regions and discussed the reasons for slope cropland changes and gained cropland instability in different regions. Finally, optimization policies were proposed to protect and control newly gained cropland.