LAUSR

Background Karst areas in southwestern China exhibit ecological degradation in the form of rocky desertification. Local governments launched large-scale afforestation and other ecological restoration programs to curb this trend. Soil thickness is a key limiting factor for vegetation restoration in Karst areas, but the relationship between ecological restoration and soil thickness remains unclear. Further, afforestation consumes large amounts of water, which impacts water supply in karst areas. In this study, we used GIS and statistical analyses to determine rocky desertification sensitivity and its driving factors in karst areas of Chongqing municipality over the past decade. Results Soil thickness is one of the key factors that restrict ecological restoration of rocky desertification. From 2000 to 2010, rocky desertification sensitivity in karst areas was on the rise along with an increase in afforestation. Areas of high sensitivity were mainly distributed in Pengshui County, Wulong District, and Youyang County; Shizhu County had the lowest overall incidence of desertification. Spatial distribution of rocky desertification was significantly affected by rainfall and soil thickness. Regression analysis showed that the main factors controlling changes in rocky desertification in natural forest over time were precipitation which explained 23.73% of total variance, and soil thickness which explained 23.42% of total variance. Soil thickness and soil water content had a higher correlation coefficient (at 0.516) in natural forests than in planted forests. Conclusion This study showed that increases in soil thickness in a karst area had a significant positive impact on the fragile ecological environment. This indicates that ecosystem restoration in karst areas will benefit from addressing soil thickness.