Frequent Dry–Hot Extremes Slow the Loss of Semi‐Arid Ecosystem Resilience

Compound dry-hot events (CDHEs) are intensifying globally, positioning the Yellow River Basin (YRB) as a critical sentinel for understanding semi-arid ecosystem stability under climate change. This study investigates the spatiotemporal dynamics of vegetation resilience in the YRB (2001-2023) by integrating satellite-derived vegetation indices (NDVI), meteorological data, and Critical Slowing Down (CSD) indicators. Testing the hypothesis of a "Resilience Paradox," we reveal a counter-intuitive buffering mechanism: while high-intensity and prolonged CDHEs accelerated resilience loss, frequent but sublethal events significantly slowed this decline by triggering ecological memory and adaptive hardening. However, this buffering capacity is not limitless; mediation analysis identifies soil moisture as a strict boundary condition, meaning "training effects" fail in severely water-limited zones. Spatially, we delineate three functional management zones requiring distinct strategies: (1) conservation of the hydrological buffer in the water-abundant Source Region; (2) strict adherence to carrying capacity limits in the frequency-driven Loess Plateau to prevent tipping; and (3) active mitigation of prolonged stress in the agricultural Lower Reaches. By linking regional resilience mechanisms to global dryland dynamics, this study offers predictive insights for ecological restoration initiatives-such as the Great Green Wall-shifting the focus from maximizing biomass to sustaining functional persistence under future compound extremes.