Precipitation sensitivity of vegetation growth in southern China depends on geological settings

Southern China is in the only humid zone at its latitudes of Northern Hemisphere and has the most extensive karst landscapes. Although the region experienced significant greening, the fragile karst geological setting and reduced precipitation may affect the greening efforts. Here we analyze the sensitivity of vegetation to precipitation between karst and non-karst areas in the region. We find that in karst areas, vegetation growth is more affected by seasonal precipitation variations (Pre_season), with relative importance of 24.02 % for Leaf Area Index (LAI) and 25.27 % for kernel Normalized Difference Vegetation Index (kNDVI). In contrast, vegetation in non-karst areas is more temperature-dominated. After controlling temperature effects, mean annual precipitation (MAP) thresholds of 1337–1438 mm are established to identify precipitation-sensitive areas (below the thresholds), with slightly higher thresholds in karst areas. These findings imply the heightened vulnerability of southern China's karst areas to ongoing drying trends, posing a threat to the region's vegetation growth and the remarkable vegetation restoration achievements.