AimDrought reduces plant growth and hastens the process of leaf senescence in autumn. Concurrently, increasing atmospheric CO2 concentrations likely amplifies photosynthetic activity while increasing plant water‐use efficiency. However, how drought affects the date of leaf senescence (DLS) and whether elevated CO2 can alleviate this remain unknown. Here, we explore the effect of drought on DLS under recent climate change and explore the underlying mechanisms.LocationNorthern mid‐high latitudes.Time Period2000–2019.Major Taxa StudiedPlants.MethodsWe conducted comprehensive analyses based on satellite remote sensing, eddy covariance flux observations, in situ phenology observations and land‐surface models. Linear regression analysis and a ten‐year moving window were adapted to investigate the spatiotemporal patterns in DLS sensitivity to drought (Sdd). The partial least squares regression method was used to attribute the main factors for the variation in Sdd, and land‐surface models in different scenarios were used to verify the robustness of the results.ResultsOur study presented divergent spatial patterns of Sdd, where the highest Sdd was concentrated in dry and warm regions. Temporally, multiple datasets consistently illustrate a significant decrease in the Sdd during recent decades (p < 0.05). We also observed a nonlinear relationship between the trend of Sdd and aridity gradient, which presented a slightly positive Sdd trend in dry regions but a negative trend in wet regions. We found these observed changes were primarily attributed to elevated CO2, alleviating the drought stress on DLS in nearly 40% of the study area.Main ConclusionsOur findings demonstrate the complex role that atmospheric CO2 plays in regulating plant leaf senescence during drought stress, highlighting the need to incorporate the effects of elevated CO2 on vegetation autumn phenology into land‐surface models for projecting vegetation growth and carbon uptake under continued global change.

中文翻译：

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大气中 CO2 上升减轻了干旱对北部中高纬度地区秋叶衰老的影响


AimDrought 会减少植物生长并加速秋季叶片衰老的过程。同时，大气中 CO2 浓度的增加可能会放大光合作用活性，同时提高植物的水分利用效率。然而，干旱如何影响叶片衰老日期 （DLS） 以及升高的 CO2 是否可以缓解这种情况仍是未知数。在这里，我们探讨了近期气候变化下干旱对 DLS 的影响，并探讨了其潜在机制。位置北部中高纬度地区。时间段2000–2019.主要分类群研究植物.方法我们基于卫星遥感、涡流协方差通量观测、原位物候观测和陆表模型进行了综合分析。线性回归分析和十年移动窗口用于研究 DLS 对干旱敏感性 （Sdd） 的时空模式。采用偏最小二乘回归法对 Sdd 变化的主要因素进行归因，并使用不同情景下的陆地表面模型来验证结果的稳健性。结果本研究呈现出 Sdd 的不同空间格局，其中最高的 Sdd 集中在干燥和温暖地区。从时间上看，多个数据集一致表明近几十年来 Sdd 显着下降 （p < 0.05）。我们还观察到 Sdd 趋势与干旱梯度之间存在非线性关系，干旱地区 Sdd 趋势略为正，而湿润地区呈负趋势。我们发现这些观察到的变化主要归因于 CO2 升高，缓解了近 40% 的研究区域对 DLS 的干旱压力。主要结论我们的研究结果表明，大气中 CO2 在干旱胁迫期间调节植物叶片衰老中起着复杂的作用，突出了将 CO2 升高对植被秋季物候的影响纳入陆表模型的必要性，以预测持续全球变化下植被生长和碳吸收。