Objective The karst region in southern China is an ecologically fragile area where karst rocky desertification is widely prevalent. Investigating the spatiotemporal changes of karst rocky desertification in southern China and its underlying mechanisms is instrumental in formulating scientific and reasonable control plans and ecological restoration measures for this phenomenon.

Methods Using Landsat 8 remote sensing imagery as the data source, information on karst rocky desertification was extracted based on fractional vegetation cover and rock exposure rate. Combined with field investigations, the spatiotemporal evolution of rocky desertification in 16 southern provinces (autonomous regions and municipalities) was analyzed at the county scale.

Results The area of karst rocky desertification in southern China was 84,472.09 km² in 2020, with light karst rocky desertification accounting for 62.75% of the total area of karst rocky desertification. From 2015 to 2020, the number of counties with karst rocky desertification areas greater than 400 km² decreased by 19. Notable improvements in karst rocky desertification were observed in Du'an County, Masan County, and Debao County in Guangxi Province; Sinan County and Weining County in Guizhou Province; Huize County and Qiubei County in Yunnan Province; and Batang County in Sichuan Province. However, the karst rocky desertification areas in Guangnan County, Wenshan City, and Yanshan County in Yunnan Province exceeded 1000 km², exacerbating the situation.

Conclusions The peaks and valleys primarily formed by dissolution were concentrated in 30% of the counties with severe karst rocky desertification. Karst rocky desertification in limestone areas accounted for more than 33% due to the intense dissolution and soil erosion processes. With the decline in rural population, the proportion of rocky desertification in cultivated land decreased to 26.54%, while the proportion of rocky desertification in shrubland and grassland increased to 20.51% and 24.11%, respectively. This study will provide a reference for the formulation of comprehensive control plans for karst rocky desertification at the county scale.