Max Planck Institute for Biogeochemistry, Hans-Knöll-Str. 10, 07745, Jena, Germany.
Department of Forest Health, Forest Research Institute Baden-Württemberg, 79100, Freiburg, Germany.
New Phytol. 2020 Jan;225(1):26-36. doi: 10.1111/nph.16173. Epub 2019 Oct 8.
Drought has promoted large-scale, insect-induced tree mortality in recent years, with severe consequences for ecosystem function, atmospheric processes, sustainable resources and global biogeochemical cycles. However, the physiological linkages among drought, tree defences, and insect outbreaks are still uncertain, hindering our ability to accurately predict tree mortality under on-going climate change. Here we propose an interdisciplinary research agenda for addressing these crucial knowledge gaps. Our framework includes field manipulations, laboratory experiments, and modelling of insect and vegetation dynamics, and focuses on how drought affects interactions between conifer trees and bark beetles. We build upon existing theory and examine several key assumptions: (1) there is a trade-off in tree carbon investment between primary and secondary metabolites (e.g. growth vs defence); (2) secondary metabolites are one of the main component of tree defence against bark beetles and associated microbes; and (3) implementing conifer-bark beetle interactions in current models improves predictions of forest disturbance in a changing climate. Our framework provides guidance for addressing a major shortcoming in current implementations of large-scale vegetation models, the under-representation of insect-induced tree mortality.
近年来，干旱导致了大规模的昆虫诱导的树木死亡，对生态系统功能、大气过程、可持续资源和全球生物地球化学循环造成了严重后果。然而，干旱、树木防御和虫害爆发之间的生理联系仍然不确定，这阻碍了我们在持续的气候变化下准确预测树木死亡的能力。在这里，我们提出了一个跨学科的研究议程，以解决这些关键的知识空白。我们的框架包括野外操作、实验室实验和昆虫与植被动态的建模，重点关注干旱如何影响针叶树和树皮甲虫之间的相互作用。我们建立在现有理论的基础上，检验了几个关键假设：（1）树木在初级和次级代谢物（如生长与防御）之间的碳投资存在权衡；（2）次级代谢物是树木抵御树皮甲虫和相关微生物的主要防御成分之一；（3）在当前的模型中实施针叶树-树皮甲虫的相互作用，可以提高对气候变化下森林干扰的预测。我们的框架为解决当前大规模植被模型实施中的一个主要缺陷提供了指导，即对昆虫诱导的树木死亡的代表性不足。
