Human disturbance intensity reduces drought resistance without prolonging recovery in karst forests of southwest China

Abstract

Role of human disturbance in shaping forest drought responses remains insufficiently understood, particularly in widely-distributed and ecologically-fragile karst landscapes. Here, we analyzed six major drought events over the past two decades in the karst forests of Southwest China, a region representative of tropical and subtropical karst ecosystems with intensive human activity. Using high-resolution gross primary productivity (GPP) and Standardized Precipitation Evapotranspiration Index (SPEI) datasets, we compared drought resistance and recovery time between low- and high-disturbance forests. High-disturbance forests experienced significantly greater maximum GPP losses during droughts, with differences reaching up to 13% under comparable drought intensities. Beyond the dominant influence of drought intensity, climatic conditions (temperature and precipitation) and soil factors (soil organic carbon and soil thickness) exerted stronger effects on drought-induced GPP loss in high-disturbance forests than in low-disturbance ones. Interestingly, despite suffering greater productivity loss, high-disturbance forests exhibited comparable, and occasionally even shorter, recovery times than low-disturbance forests, suggesting a possible trade-off between drought resistance and recovery capacity. Although recovery time was not consistently prolonged, the greater productivity losses and elevated climatic and edaphic sensitivity in high-disturbance forests indicate reduced resistance and heightened vulnerability to future climate extremes and progressive drying trends.