Multidimensional Vegetation Drought Response to Meteorological and Soil Moisture Deficits Across the Yellow River Basin

Drought poses substantial threats to terrestrial ecosystems, yet whether vegetation vulnerability patterns systematically diverge between soil moisture and meteorological droughts—and how long-term hydrological adaptation governs ecosystem susceptibility to rare extreme droughts—remains poorly understood. Here, we systematically quantify vegetation responses to soil moisture drought (Standardized Soil Moisture Index, SSI) and meteorological drought (3-month Standardized Precipitation Evapotranspiration Index, SPEI-3) across the Yellow River Basin from 1982 to 2022, examining resistance, resilience, and peak loss alongside their spatial differentiation and temporal lags. SSI and SPEI-3 identified droughts exhibit distinct event characteristics: meteorological droughts occur more frequently with shorter durations, whereas soil moisture droughts persist 2–3 times longer once initiated, consistent with the buffering and memory effects of soil water storage. Vegetation response patterns diverge substantially between drought definitions, with SSI-derived resistance showing stronger associations with drought duration, whereas SPEI-3 conditions elevate the importance of drought-period climate. Wetter regions and deciduous-mixed forests exhibit the highest standardized peak losses despite comparable or higher resistance, consistent with the hypothesis that vegetation adapted to long-term water-abundant conditions may be more susceptible to rare extremes. Random Forest and SHapley Additive exPlanations analyses demonstrate that resistance is associated with drought attributes and drought-period climatic conditions, resilience is strongly associated with drought-period temperature and post-drought climate conditions, and peak loss shows the strongest background environmental dependence. Temporal lags between peak vegetation loss and drought intensity vary spatially, with stronger heterogeneity under SSI than SPEI-3. Our findings demonstrate that comprehensive vulnerability assessment requires integrating complementary drought metrics and multidimensional response frameworks, providing critical insights for improving drought monitoring, ecological risk assessment, and sustainable ecosystem management under climate change.