Tree defense in a changing world

碳（C）是生命的核心元素，因为它可以与其他元素结合形成复杂的分子，对植物和动物的新陈代谢很重要。通过光合作用吸收的碳在植物的生长、生存和繁殖中起着重要作用，因为它们不能通过迁移来逃避干旱等压力，而只能通过战略性地分配资源来维持生命功能和代谢所需化合物的生物合成。直接参与生长、发育和繁殖的化合物被称为初级代谢物，而次级代谢物（SM）对于物种相互作用、解毒和防御非常重要。C的分配对地球上的生命也起着关键作用，因为它通过陆地植被引导太阳能并驱动全球生物地球化学循环（例如，能源、水、营养物），并介导商品生产、气候调节或生物多样性保护等生态系统服务的提供。然而，快速变化的气候正在对全球植被构成越来越大的威胁，气候变化引起的植被死亡在所有植被覆盖的大陆都有记录。这种死亡率通常是由气候、植物生理学和植物拮抗剂（例如，食草动物），并可能导致大规模植被死亡，例如森林因流行性树皮甲虫爆发而死亡。然而，对气候变化引起的植被死亡的研究往往忽视了生物因子和树木防御（即次生代谢）的作用，因此无法为植被模拟模型等预测工具提供机制关系。关于环境线索与植物初级和次级代谢之间联系的理论在几十年前就已经发展起来，但仍然缺乏经验支持，而且在快速的环境变化下可能不成立。该项目针对植物防御对持续环境变化的响应的三个重要知识缺口：1）气候变化如何影响全球树木防御模式，特别是在干旱期间和不同物种之间; 2）不同防御水平如何影响重要森林害虫的发展和生活史，欧洲云杉树皮甲虫及其相关真菌和3）使用来自2的信息，以改善预测树皮甲虫干扰在中欧森林。该项目具有挑战性，但非常有前途，因为它不仅建立在综合跨学科研究的基础上，结合了生态场操作，生理分析和生化测定，而且还利用了跨越各种物种和几个生物群落的跨大陆合作。

Carbon (C) is the central element of life because it can bind with other elements to form complex molecules that are important for plant and animal metabolism. C assimilated via photosynthesis plays a fundamental role in growth, survival and reproduction of plants, as they cannot escape stressful situations like drought by migration but only via strategically allocating resources to life-sustaining functions and biosynthesis of compounds required for metabolism. Compounds that are directly involved in growth, development, and reproduction are called primary metabolites while secondary metabolites (SM) are important for species interactions, detoxification and defense.Allocation of C plays also a critical role for life on Earth as it channels solar energy through the terrestrial vegetation and drives global biogeochemical cycles (e.g., energy, water, nutrients) and mediates provision of ecosystem services such commodity production, climate regulation or biodiversity conservation. Yet, rapidly changing climate is posing an increasing threat to the global vegetation and climate change-induced vegetation mortality has been documented across all vegetated continents. Such mortality is most often driven by an interaction between climate, plant physiology and plant antagonists (e.g., herbivores) and can lead to large-scale vegetation mortality like forest die off from epidemic bark beetle outbreaks.However, investigations of climate changed-induced vegetation mortality often neglect the role of biotic agents and tree defense, i.e. secondary metabolism, and thus cannot provide mechanistic relationships for predictive tools like vegetation simulation models. Theories on the linkages between environmental cues and the plants’ primary and secondary metabolism have been developed decades ago but still lack empirical support, and likely do not hold under rapid environmental change. Such gaps lead to substantial incertitude about the fate of the Earth’s future vegetation.The suggested project targets three important knowledge gaps of plant defense responses to ongoing environmental change: 1) how does climate change influence patterns of tree defense globally, in particular during drought and across different species; 2) how do different levels of defense influence the development and the life cycle of an important forest pest, the European spruce bark beetle as well as its associated fungus and 3) use information derived from 2 to improve predictions of bark beetle disturbance in central European forests. This project is challenging but highly promising as it builds not only on integrative transdisciplinary research that combines ecological field manipulations, physiological analysis and biochemical assays, but also capitalizes on transcontinental collaborations spanning a large variety of species and several biomes.