Abstract Extreme drought events exert both immediate and prolonged influences on terrestrial ecosystems, yet the patterns and mechanisms of the delayed effects of extreme drought on alpine ecosystems remain largely unknown. In this study, we use satellite-derived normalized difference vegetation index (NDVI) data to examine the legacy effect of severe drought events on vegetation greenness across the Tibetan Plateau (TP). A pervasive, negative drought legacy effect, lasting about one year, is detected for all plant functional types including forests, shrubs and grasslands on the TP. The magnitude of the identified legacy effect, namely, the reduced growing-season NDVI in the first year post-drought, is spatially heterogeneous and exhibits a clear altitude dependence, while divergent relationships between elevation and the legacy effect are observed between alpine meadow and steppe. For alpine meadow, more pronounced legacy effects occur at higher altitudes with lower precipitation and temperature, suggesting a weaker drought resilience of alpine meadow under dryer and colder conditions. Whereas for alpine steppe, the magnitude of the negative legacies reduces as precipitation decreases along the elevation, which might be due to a greater adaptability to drought under more arid conditions that enables plant communities to recover to their normal state faster in these very dry regions. Our results advance the understanding of drought legacy effects on TP alpine ecosystems and highlight future avenues for research into how different alpine ecosystem types will respond to drought stress.

中文翻译：

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青藏高原干旱遗留效应对植被绿度的海拔依赖性

摘要 极端干旱事件对陆地生态系统既有直接影响，也有长期影响，但极端干旱对高寒生态系统延迟影响的模式和机制仍然未知。在这项研究中，我们使用卫星衍生的归一化植被指数 (NDVI) 数据来检查严重干旱事件对青藏高原 (TP) 植被绿度的遗留影响。对于青藏高原上的所有植物功能类型，包括森林、灌木和草地，都检测到了普遍的、持续约一年的负面干旱遗留效应。确定的遗留效应的大小，即干旱后第一年生长季节 NDVI 的减少，在空间上是异质的，表现出明显的高度依赖性，而在高寒草甸和草原之间观察到海拔和遗产效应之间的不同关系。对于高寒草甸，更明显的遗留效应发生在降水和温度较低的高海拔地区，表明在干燥和寒冷条件下高寒草甸的抗旱能力较弱。而对于高山草原，负遗产的程度随着降水沿海拔的减少而减少，这可能是由于在更干旱的条件下对干旱的适应性更强，使这些非常干燥地区的植物群落能够更快地恢复到正常状态。我们的研究结果促进了对干旱遗产对 TP 高山生态系统影响的理解，并突出了研究不同高山生态系统类型将如何应对干旱压力的未来途径。