Soil Property Plays a Vital Role in Vegetation Drought Recovery in Karst Region of Southwest China

Southwest China is the world's largest continuous karst region, where drought events are expected to intensify in the future. Understanding the postdrought recovery of vegetation growth sheds light on the resilience and stability of ecosystems and is of great importance to the sustainable management. However, the effects of the soil properties, beyond the climate variations, on the vegetation postdrought recovery are often overlooked and remain unknown. In this study, we characterized both the patterns and the underlying processes governing the postdrought recovery trajectories of vegetation growth after extreme droughts in karst regions of southwest China. Linear mixed-effects model analyses revealed that higher mean Normalized Difference Vegetation Index (NDVI) preceding the spring/summer drought leads to shorter drought recovery time for both forests and grasslands, while opposite pattern appears in autumn/winter drought, particularly in forests. Significant effects of precipitation during recovery period were only found in grasslands but not in forests. More importantly, we discovered a crucial impact of the depth to bedrock on vegetation postdrought recovery in forests but not in grasslands, with deeper depth to bedrock associated to a shorter drought recovery. The field capacity is more important for postdrought recovery in karst regions than in nonkarst regions, which can be most likely attributed to differences in the water-holding capacities and water use strategies of vegetation. Our understanding of the postdrought recovery of vegetation growth in karst regions will facilitate the reasonable prediction of ecosystem resilience and health to extreme climate events in such fragile ecological environments.