Subtropical forests, recognized for their intricate vertical canopy stratification, exhibit high resistance to extreme drought. However, the response of leaf phenology to drought in the species‐rich understory remains poorly understood. In this study, we constructed a digital camera system, amassing over 360,000 images through a 70% throughfall exclusion experiment, to explore the drought response of understory leaf phenology. The results revealed a significant advancement in understory leaf senescence phenology under drought, with 11.75 and 15.76 days for the start and end of the leaf‐falling event, respectively. Pre‐season temperature primarily regulated leaf development phenology, whereas soil water dominated the variability in leaf senescence phenology. Under drought conditions, temperature sensitivities for the end of leaf emergence decreased from −13.72 to −11.06 days °C−1, with insignificance observed for the start of leaf emergence. Consequently, drought treatment shortened both the length of the growing season (15.69 days) and the peak growth season (9.80 days) for understory plants. Moreover, this study identified diverse responses among intraspecies and interspecies to drought, particularly during the leaf development phase. These findings underscore the pivotal role of water availability in shaping understory phenology patterns, especially in subtropical forests.

中文翻译：

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干旱通过促进叶子衰老缩短亚热带林下生长季节

亚热带森林以其复杂的垂直冠层分层而闻名，对极端干旱表现出很强的抵抗力。然而，在物种丰富的林下，叶子物候对干旱的反应仍然知之甚少。在这项研究中，我们构建了一个数码相机系统，通过 70% 的穿透排除实验收集了超过 360,000 张图像，以探索林下叶物候的干旱响应。结果显示，干旱条件下林下叶片衰老物候显着进步，落叶事件开始和结束分别为 11.75 天和 15.76 天。季前温度主要调节叶片发育物候，而土壤水主导叶片衰老物候的变化。在干旱条件下，出叶结束时的温度敏感性从-13.72天℃下降到-11.06天℃−1，对于叶子出现的开始观察到的意义微不足道。因此，干旱处理缩短了林下植物的生长季节（15.69 天）和高峰生长季节（9.80 天）。此外，这项研究还确定了种内和种间对干旱的不同反应，特别是在叶子发育阶段。这些发现强调了水的可用性在塑造林下物候模式中的关键作用，特别是在亚热带森林中。