Divergent leaf senescence changes in meadows, steppes, and cultivated vegetation on the Qinghai–Tibetan Plateau

Temporal changes in autumn leaf senescence dates and their drivers across meadows, steppes, and cultivated vegetation on the Qinghai–Tibetan Plateau (QTP) remain poorly understood. Using long-term ground observation data from 12 sites, we analyzed interannual change trends in leaf senescence date and quantified the influences of climatic factors (i.e., temperature, precipitation, and sunshine duration), soil moisture, and spring phenology on its shifts. Meadows showed a significant delaying trend (0.891 days/year), mainly driven by substantial increases in air temperature and precipitation during the growing season, particularly in the late season. Steppes exhibited an overall insignificant delaying trend (0.214 days/year), where the delaying effects of increased precipitation and reduced sunshine duration were partly offset by the late-season soil moisture decline. In cultivated vegetation, a slight advance in leaf senescence date (−0.108 days/year) was primarily caused by earlier spring green-up date, supplemented by increased temperature and precipitation during the growing season, which led plants to grow earlier and complete their life cycles sooner. Climatic influences were stronger in the late season for meadows but greater in the early season for steppes. Compared with meadows and steppes, spring phenology had the strongest effect on the timing of leaf senescence in cultivated vegetation. These findings advance our understanding of vegetation phenological shifts on the QTP and highlight the necessity of incorporating the notable differences across vegetation types into both phenological models and ecosystem management practices.