The Response and Attribution of Vegetation Productivity to Drought Sensitivity in Northwest China

Drought strongly reduces vegetation productivity and is expected to worsen with climate change; however, long-term patterns and mechanisms of the drought sensitivity of vegetation (Sdro) remain unclear for arid–semiarid Northwest China (NWC). Using satellite GPP and soil-moisture records (1982–2018), in this study, we (1) quantified spatiotemporal drought trends, (2) assessed Sdroacross major vegetation types, and (3) attributed Sdrochanges using a hierarchical segmentation mixed-effects model. We found a small but significant regional increase in drought (0.5 × 10⁻³ yr⁻¹), concentrated in the southeastern Tibetan Plateau and the Qilian and Tianshan Mountains, while declines were found in the Loess Plateau, Guanzhong Plain, and Ordos Basin. Overall, 52% of NWC shows positive drought sensitivity and Sdroincreased regionally at 0.004 yr⁻¹ (pdro(73.2% and 63.3%), but only alpine meadow showed a declining trend; moreover, croplands showed the largest increase in Sdro. Vapor pressure deficit (VPD) and precipitation (Pre) are the dominant controls (VPD was positively correlated with Sdroin 89.1% of the area; Pre was negatively correlated with Sdroin 81.1% of the area), with alpine meadows mainly influenced by Pre and temperature and temperate grasslands by solar radiation. These results clarify where and why vegetation in NWC is becoming more drought-sensitive, thus providing targeted information for regional drought management and ecosystem resilience planning.