Vegetation sensitivity to drought depends on bedrock type in a subtropical karst landscape in Southwest China

Droughts pose a significant global threat to ecosystem stability and plant diversity. The sensitivity of vegetation to drought is highly variable, influenced by both vegetation types and landscape properties. However, little is known about whether bedrock type influences vegetation drought sensitivity, especially in karst regions, where unique hydrogeology creates severe water stress for surface vegetation. In this study, we quantify the effect of bedrock types (i.e., limestone, dolomite, and clastic rocks) on vegetation drought sensitivity karst regions across Guizhou Province (China). We found that during the early growing season, vegetation sensitivity to drought was 1.3-1.8 times higher in limestone areas than in dolomite and clastic areas. We also determined that the duration of dry spells is a critical temporal factor that amplifies drought stress. Hierarchical modeling indicated that models jointly incorporating bedrock type and dry spell duration significantly improve predictions of vegetation activity. These findings highlight the crucial role bedrock's in shaping vegetation growth under drought conditions, supporting the integration of bedrock data into hydrologic and climate models to improve their predictive accuracy under drought stress.