Abstract Intense spring freezing events can kill the recently produced cohort of leaves, forcing trees to expend additional carbon and nutrient stocks to produce a second cohort of leaves. The future trends in the frequency of late spring frosts will affect the adaptation of some tree species to their current habitats. Here we studied the effect of a late frost which occurred in 2017 on a mixed beech (Fagus sylvatica)-oak (Quercus petraea) forest located in central Spain, where these species reach their southernmost distribution limits. We followed a multi-scale approach from organ to forest levels. At the organ level, leaf and stem morphological and biochemical traits were compared between frost-damaged and non-damaged trees. At the tree level, we compared the 2017 radial growth between damaged and non-damaged trees. At the stand level, the 2017 Leaf Area Index (LAI) and daily variations of NDVI during 2017 were compared with those of average years in areas dominated by beech and oak. Finally, at the forest scale, daily NDVI dynamics during 2017 were compared with those of the three previous years. According to our results, beech trees damaged by late frost kept non-structural carbohydrate (NSC) concentrations stable by drastically reducing wood production. This growth reduction could compensate for the drop in carbon inputs due to the death of the first leaf cohort, the need to form a second leaf cohort, the one-month delay between both leaf flushes and the smaller photosynthetic surface of the second leaf cohort. In contrast, although the frost-damaged oaks lost the first cohort of leaves and formed a second one, no differences in leaf individual area and phenology, nor stem NSC concentrations and radial growth were found when comparing damaged and non-damaged oaks. The differential response between both tree species seems to provide oak with a competitive advantage over beech.

中文翻译：

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橡树和山毛榉对晚霜冻害的不同反应：从器官到森林的综合分析

摘要 春季强烈的冰冻事件会杀死最近产生的一批叶子，迫使树木消耗额外的碳和营养储备来生产第二批叶子。晚春霜冻频率的未来趋势将影响一些树种对其当前栖息地的适应。在这里，我们研究了 2017 年发生的晚霜对位于西班牙中部的混合山毛榉（Fagus sylvatica）-橡木（Quercus petraea）森林的影响，这些物种在那里达到了最南端的分布极限。我们遵循从器官到森林层次的多尺度方法。在器官水平上，比较冻害和未受害树木的叶和茎形态和生化性状。在树木层面，我们比较了 2017 年受损树木和未受损树木之间的径向生长情况。在展台层面，将2017年叶面积指数（LAI）和2017年NDVI日变化与山毛榉和橡树为主的地区的平均年份进行比较。最后，在森林尺度上，将 2017 年的每日 NDVI 动态与前三年进行了比较。根据我们的研究结果，被晚霜损坏的山毛榉树通过大幅减少木材产量来保持非结构性碳水化合物 (NSC) 浓度的稳定。这种生长减少可以补偿由于第一个叶群死亡、需要形成第二个叶群、两次叶潮之间的一个月延迟和第二个叶群较小的光合表面而导致的碳输入下降。相比之下，虽然受霜冻损害的橡树失去了第一批叶子并形成了第二批叶子，但叶子个体面积和物候没有差异，在比较受损和未受损的橡树时，也没有发现茎 NSC 浓度和径向生长。两种树种之间的差异反应似乎使橡木比山毛榉具有竞争优势。