Distribution pattern of rocky desertification in southwest China and analysis of its main driving factors based on GIS and Geodetector

Rocky desertification, a pressing environmental concern in Southwest China, significantly impacts local living conditions and regional sustainability. Employing remote sensing on a macro scale, this study focuses on identifying and analyzing the spatial distribution and driving factors of rocky desertification. Conducted in Southwest China, using Landsat data from Google Earth Engine for 2020, the research quantitatively extracts information on rocky desertification patches through traditional methods. Excluding unlikely areas using land use data, spatial distribution features and driving factors are examined via GIS spatial analysis and a geodetector model. The main conclusions are as follows. Rocky desertification covers 217,530.4 km2 (accounting for 15.6% of Southwest China), with areas of slight, moderate, and severe rocky desertification at 81.3%, 7.1%, and 11.6%, respectively. Spatially, rocky desertification primarily occurs in areas where lithology is carbonate rock between clastic rocks and continuous limestone, slope exceeds 15°, elevation ranges is 1000–2000 m, land use types are grassland and woodland, precipitation is 80–120 mm, and population density is below 50 people/km2. Human activities have minimal influence. Geodetector analysis identifies lithology, land use type, and slope as primary driving factors, with interactive effects of lithology and land use type and slope and land use type jointly influencing rocky desertification formation in Southwest China.

Methods
The rocky desertification data were obtained from Landsat 8 operational land imager (OLI) image data provided by the U.S. Geological Survey (USGS) ("https://www.usgs.gov"), de-clouded based on the Google Earth Engine (GEE), and atmospherically corrected using ENVI5.3 Fast line-of-sight atmospheric analysis of spectral hypercubes (FLAASH) atmospheric correction tool with a spatial resolution of 30 m [37,38]. The land use type data with a spatial resolution of 1000 m were downloaded from the Resource and Environmental Science and Data Center of the Chinese Academy of Sciences ("https://www.resdc.cn"). The land use types in these data mainly include watersheds, rivers, and urban industrial construction land, cultivated land, woodland, grassland, and unutilized land. The overall accuracy of this dataset reached 95.41%, which met the needs of this study. The digital elevation model (DEM) data for the study area were obtained from the Geospatial Data Cloud Platform of the Computer Network Information Center of the Chinese Academy of Sciences ("http://www.gscloud.cn"), with a spatial resolution of 30 m. The precipitation data for 2020 were obtained from the China Meteorological Administration ("http://www.cma.gov.cn/"). The monthly average precipitation data of Southwest China for 2020 were obtained after kriging interpolation. The population density data were obtained from the 2020 Yearbook of the National and Local Government Statistical Bureau ("http://www.stats.gov.cn/tjsj/ndsj/").