Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan, 430074, P.R. China.
University of Chinese Academy of Sciences, Beijing, 100049, P.R. China.
Glob Chang Biol. 2023 Jun;29(12):3463-3475. doi: 10.1111/gcb.16675. Epub 2023 Mar 20.
Trees at their upper range limits are highly sensitive to climate change, and thus alpine treelines worldwide have changed their recruitment patterns in response to climate warming. However, previous studies focused only on daily mean temperature, neglecting the asymmetric influences of daytime and nighttime warming on recruitments in alpine treelines. Here, based on the compiled dataset of tree recruitment series from 172 alpine treelines across the Northern Hemisphere, we quantified and compared the different effects of daytime and nighttime warming on treeline recruitment using four indices of temperature sensitivity, and assessed the responses of treeline recruitment to warming-induced drought stress. Our analyses demonstrated that even in different environmental regions, both daytime and nighttime warming could significantly promote treeline recruitment, and however, treeline recruitment was much more sensitive to nighttime warming than to daytime warming, which could be attributable to the presence of drought stress. The increasing drought stress primarily driven by daytime warming rather than by nighttime warming would likely constrain the responses of treeline recruitment to daytime warming. Our findings provided compelling evidence that nighttime warming rather than daytime warming could play a primary role in promoting the recruitment in alpine treelines, which was related to the daytime warming-induced drought stress. Thus, daytime and nighttime warming should be considered separately to improve future projections of global change impacts across alpine ecosystems.
在其上限范围内，树木对气候变化高度敏感，因此全球高山树线已经改变了它们的繁殖模式以应对气候变暖。然而，以前的研究仅关注日平均温度，而忽略了白天和夜间变暖对高山树线繁殖的不对称影响。在这里，基于北半球 172 条高山树线的树木繁殖系列汇编数据集，我们使用四个温度敏感性指数量化和比较了白天和夜间变暖对树线繁殖的不同影响，并评估了树线繁殖对变暖引起的干旱胁迫的响应。我们的分析表明，即使在不同的环境区域，白天和夜间变暖都可以显著促进树线繁殖，然而，树线繁殖对夜间变暖的敏感性远高于白天变暖，这可能归因于干旱胁迫的存在。主要由白天变暖而不是夜间变暖驱动的不断增加的干旱胁迫可能会限制树线繁殖对白天变暖的响应。我们的研究结果提供了令人信服的证据，表明夜间变暖而不是白天变暖可能在促进高山树线的繁殖中发挥主要作用，这与白天变暖引起的干旱胁迫有关。因此，为了提高对高山生态系统中全球变化影响的未来预测，应该分别考虑白天和夜间变暖。
