Abstract：
Extreme droughts can have long-lasting effects on forest community dynamics and species interactions. Yet, our understanding of how drought legacy modulates ecological relationships is just unfolding. We tested the hypothesis that leaf chemistry and herbivory show long-term responses to premature defoliation caused by an extreme drought event in European beech (Fagus sylvatica L.). For two consecutive years after the extreme European summer drought in 2018, we collected leaves from the upper and lower canopy of adjacently growing drought-stressed and unstressed trees. Leaf chemistry was analyzed and leaf damage by different herbivore-feeding guilds was quantified. We found that drought had lasting impacts on leaf nutrients and on specialized metabolomic profiles. However, drought did not affect the primary metabolome. Drought-related phytochemical changes affected damage of leaf-chewing herbivores whereas damage caused by other herbivore-feeding guilds was largely unaffected. Drought legacy effects on phytochemistry and herbivory were often weaker than between-year or between-canopy strata variability. Our findings suggest that a single extreme drought event bears the potential to long-lastingly affect tree-herbivore interactions. Drought legacy effects likely become more important in modulating tree-herbivore interactions since drought frequency and severity are projected to globally increase in the coming decades.
摘要：
极端干旱会对森林群落动态和物种相互作用产生长期影响。然而，我们对干旱遗产如何调节生态关系的理解正在展开。我们测试了以下假设：叶片化学和食草动物对欧洲山毛榉（FagussylvaticaL.）的极端干旱事件引起的过早落叶具有长期响应。在2018年欧洲夏季极端干旱之后的连续两年中，我们从相邻生长的干旱胁迫和无胁迫树木的上下冠层中收集叶子。分析了叶片化学，并量化了不同食草动物饲喂行会对叶片的损害。我们发现干旱对叶片养分和专门的代谢组学谱具有持久的影响。然而,干旱并不影响初级代谢组。与干旱有关的植物化学变化影响了咀嚼叶片的食草动物的损害，而其他食草动物饲喂行会造成的损害在很大程度上不受影响。干旱对植物化学和草食性的影响通常弱于年际或冠层间的变化。我们的发现表明，单个极端干旱事件具有长期持久影响树木与食草动物相互作用的潜力。由于干旱的频率和严重程度预计在未来几十年将在全球范围内增加，干旱的遗产效应可能在调节树木-草食动物的相互作用方面变得更加重要。
