Purpose of Review

Nonstructural carbohydrates (NSC) promote tree survival when photosynthesis is impeded by factors whose impact is expected to increase under climate change, like droughts, herbivory, and fires. Nonetheless, it remains unclear whether NSC are depleted under natural conditions and if they mediate tree recovery. To determine if there is a general pattern of NSC variation, we reviewed the recent (2008–2018) literature reporting NSC changes in response to droughts, insect herbivory, and fires, in woody species under natural conditions.

Recent Findings

We found 25 cases in 16 studies examining NSC dynamics post-drought, most of them conducted in species of Pinaceae or Fagaceae in Mediterranean Europe. Drought-affected trees had lower NSC, starch, and sugars concentrations than unaffected counterparts, although these results were entirely driven by roots and trunks of Pinaceae. We found only six studies examining NSC responses to herbivory, which indicate both increases and decreases in NSC concentrations inconsistently related to changes in growth or survival. Fire led to consistent decreases in NSC that mediated a successfully regrowth in absence of drought.

Summary

NSC decrease related equivocally to the occurrence of drought, fire, and herbivory and also to post-disturbance recovery, indicating no clear pattern of decreasing forest resilience under current climate change. An exception seems to be Pinaceae, which showed decreased NSC and performance in response to drought or herbivory. We suggest that a more water conservative strategy and smaller NSC pools in gymnosperms relative to angiosperms underlie these results.

中文翻译：

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气候变化下非结构性碳水化合物的储存在森林抗灾力中的作用

审查目的

当预期在气候变化下其影响会增加的因素（例如干旱，草食和火灾）阻碍光合作用时，非结构性碳水化合物（NSC）会促进树木的生存。尽管如此，目前尚不清楚NSC是否在自然条件下枯竭以及它们是否介导树木恢复。为了确定是否存在NSC变化的一般模式，我们回顾了最近（2008-2018年）的文献，其中报道了NSC在自然条件下对干旱，昆虫食草和火灾响应的变化。

最近的发现

我们在16个研究中发现了25个案例，这些案例研究了干旱后NSC的动态，其中大多数是在地中海欧洲的松科或菊科物种中进行的。受干旱影响的树木的NSC，淀粉和糖含量低于未受灾的树木，尽管这些结果完全由松科的根和树干驱动。我们发现只有六项研究检查了NSC对草食动物的反应，这表明NSC浓度的增加和减少与生长或存活的变化不一致。大火导致NSC持续下降，这在没有干旱的情况下介导了成功的再生长。

概要

NSC的减少与干旱，火灾和食草的发生以及扰动后的恢复模棱两可，这表明在当前气候变化下，森林抗灾力没有明显下降的趋势。松科似乎是一个例外，它显示出对干旱或食草的响应，NSC和性能下降。我们建议，相对于被子植物，裸子植物中更节水的策略和较小的NSC库是这些结果的基础。