Abstract: Aiming at the problem of limited time and space scale in the study of cropland change in rocky desertification area, this paper takes Fuyuan county as an example, based on Landsat remote sensing data from 1990, 2000, 2010, and 2019, uses the classification method of multi-feature and random forest to extract cropland, uses cropland coverage, cropland type conversion and slope zonal statistics to analyze the characteristics of the spatial-temporal cropland change in the past 30 years (1990-2019), and discusses the driving forces for cropland change. The results show that the cropland area in Fuyuan county increased firstly (1990-2010) and then decreased (2010-2019). The main sources and transformation types of cropland area are woodland and grassland, with woodland being the most. It is mainly distributed in five towns with less rocky desertification area in the north, and mainly in the gentle slope area. The cropland coverage show a process from low to high to low, and the cropland change rate in the steep slope area vary significantly in different periods. The cropland change in Fuyuan county has been formed by the combined effects of population, economic, policy, and transportation factors under the unique geographical environment of rocky desertification area in the past 30 years. The conclusions of this paper can provide data support for the assessment of ecological security and food security in rocky desertification area.

Key words: rocky desertification area, cropland, spatial-temporal change, type conversion, zonal statistics