Quantifying effective wind loads on trees through analysis of crown reconfiguration (TreeCon)

在过去的70年里，风暴是欧洲森林面临的最严重的自然灾害。当树木暴露在破坏性的风荷载下时，就会发生风暴破坏。由于其广泛的范围，冬季风暴造成的最大数量的损坏木材。在过去的30年里，冬季风暴对欧洲森林木材破坏的重要性有所增加。七场最严重的冬季风暴中有六场发生在1990年之后。在过去，针叶树种特别受到冬季风暴的影响，因为与落叶树种不同，它们全年都保留着针叶。冬季树叶有效地促进动能从近地面气流转移到树冠，因为它们暴露在风中的表面积很大。鉴于气候持续变化，可以预计，未来除了冬季风暴外，对流风暴事件将更加频繁，导致树木和森林全年受损，特别是在夏季。破坏性对流风暴事件的全年发生将减少落叶树种的季节性树叶的优势。风暴事件会降低受影响地区剩余林分的活力，诱发次生生物自然灾害，如树皮甲虫侵扰，并造成经济损失。风暴破坏影响到生态系统服务，如木材生产、娱乐功能、水和侵蚀控制以及二氧化碳固存。灾难性风暴可以在短时间内大大减少森林的二氧化碳吸收能力。全面了解作用在树木上的风荷载对于最大限度地减少风暴对树木和森林的破坏至关重要。(i)虽然许多以前的研究（包括我自己的）已经确定和描述的风树相互作用的模式，（ii）仍然有一个基本的知识差距，关于绝对瞬时的风荷载的大小，触发风树的相互作用。这种基本的知识差距的存在，因为只有基本的定量知识是关于变形（重新配置）的树冠在实际的风力条件下。重构在确定向树冠传递动能的过程中起着至关重要的作用。TreeCon项目旨在解决这一知识差距。预期的结果和相关的新见解将有助于尽量减少未来风暴对树木和森林的破坏。为了获得这一新知识，将采用一种新颖的、具有成本效益的测量系统，并将其与现有的测量系统相结合，解决以前未回答的问题并测试假设。该测量系统特别适用于落叶树木的研究。

In the past 70 years, storms have posed the most significant natural hazard to European forests. Storm damage occurs when trees are exposed to destructive wind loads. Due to their widespread extent, winter storms caused the largest amounts of damaged timber. The significance of winter storms in terms of timber damage in European forests has increased in the last 30 years. Six out of the seven most severe winter storms occurred after 1990. In the past, coniferous tree species were particularly affected by damage from winter storms because, unlike deciduous species, they retain their needles throughout the year. Winter foliage efficiently facilitates kinetic energy transfer from the near-surface airflow to the tree crowns due to their large surface area exposed to the wind. Given the ongoing climate change, it can be expected that in the future, in addition to winter storms, convective storm events will become more frequent, leading to tree and forest damage year-round, especially in summer. The year-round occurrence of destructive convective storm events will diminish the advantage of seasonal foliage in deciduous tree species. Storm events can reduce the vitality of remaining stands in affected regions, induce secondary biotic natural hazards such as bark beetle infestations, and result in economic loss. Storm damage affects ecosystem services such as timber production, recreational functions, water and erosion control, and carbon dioxide sequestration. Catastrophic storms can significantly reduce forests' carbon dioxide sink capacity in a short exposure time. Comprehensive knowledge of wind loads acting on trees is fundamental to minimizing storm damage to trees and forests. (i) While numerous previous studies (including my own) have identified and described patterns of wind-tree interactions, (ii) there is still a fundamental knowledge gap concerning the absolute instantaneous magnitudes of wind loads that trigger wind-tree interactions. This fundamental knowledge gap exists because only rudimentary quantitative knowledge is available regarding the deformation (reconfiguration) of tree crowns under actual wind conditions. Reconfiguration plays a crucial role in determining the transfer of kinetic flow energy to tree crowns. The TreeCon project aims to address this knowledge gap. The expected results and associated new insights will contribute to minimizing future storm damage to trees and forests. To acquire this new knowledge, a novel, cost-effective measurement system will be employed and integrated with existing measurement systems, resolving previously unanswered questions and testing hypotheses. This measurement system is particularly suitable for studies on deciduous trees.