Research Highlights: Bark beetles are important agents of disturbance regimes in temperate forests, and specifically in a connected wind-bark beetle disturbance system. Large-scale windthrows trigger population growth of the European spruce bark beetle (Ips typographus L.) from endemic to epidemic levels, thereby allowing the killing of Norway spruce trees over several consecutive years. Background and Objectives: There is a lack of evidence to differentiate how outbreaks are promoted by the effects of environmental variables versus beetle preferences of trees from endemic to outbreak. However, little is known about how individual downed-tree characteristics and local conditions such as tree orientation and solar radiation affect beetle colonization of downed trees. Materials and Methods: To answer this question, we investigated the infestation rates and determined tree death categories (uprooted, broken, and stump) in wind-damaged areas in Western Tatra Mts. in Carpathians (Slovakia) from 2014–2016, following a windthrow in May 2014. In total, we investigated 225 trees over eight transects. For every tree, we measured its morphological (tree height, crown characteristics), environmental (solar radiation, terrain conditions, trunk zenith), temporal (time since wind damage), and beetle infestation (presence, location of attack, bark desiccation) parameters. We applied Generalized Additive Mixed Models (GAMM) to unravel the main drivers of I. typographus infestations. Results: Over the first year, beetles preferred to attack broken trees and sun-exposed trunk sides over uprooted trees; the infestation on shaded sides started in the second year along with the infestation of uprooted trees with lower desiccation rates. We found that time since wind damage, stem length, and incident solar radiation increased the probability of beetle infestation, although both solar radiation and trunk zenith exhibited nonlinear variability. Our novel variable trunk zenith appeared to be an important predictor of bark beetle infestation probability. We conclude that trunk zenith as a simple measure defining the position of downed trees over the terrain can anticipate beetle infestation. Conclusions: Our findings contribute to understanding of the bark beetle’s preferences to colonize windthrown trees in the initial years after the primary wind damage. Further, our findings can help to identify trees that are most susceptible to beetle infestation and to prioritize management actions to control beetle population while maintaining biodiversity.

中文翻译：

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严重风吹后云杉树皮甲虫（Ips typographus）的侵害

研究重点：树皮甲虫是温带森林，特别是在相连的风树皮甲虫干扰系统中干扰机制的重要推动力。大规模的大风引发欧洲云杉树皮甲虫（Ips typographusL.）从流行到流行的程度，从而使挪威云杉树木连续数年被杀死。背景和目的：缺乏证据来区分环境变量与甲虫对流行的影响（从流行到暴发）如何促进暴发。但是，人们对单个倒下的树木特征和局部条件（例如树木的方向和太阳辐射）如何影响倒下的树木的甲虫定植知之甚少。材料和方法：为了回答这个问题，我们调查了西塔特拉山风灾地区的病虫害发生率并确定了树木死亡类别（连根拔起，折断和残肢）。2014年5月大风吹过之后，2014-2016年在喀尔巴阡（斯洛伐克）进行了调查。我们总共调查了8个样带的225棵树。对于每一棵树，我们测量了它的形态（树高，树冠特征），环境（太阳辐射，地形条件，树干天顶），时间（自风害起的时间）和甲虫侵染（存在，攻击位置，树皮干燥）参数。我们应用了广义可加混合模型（GAMM）来阐明印刷术侵扰。结果：在第一年中，甲虫更喜欢攻击连根拔起的树木上的破树和阳光直射的树干侧面；阴影侧的侵扰始于第二年，同时干燥率较低的连根拔起的树木也开始侵扰。我们发现自风害，茎长和入射太阳辐射以来的时间增加了甲虫侵扰的可能性，尽管太阳辐射和树干天顶均表现出非线性变化。我们新颖的可变树干天顶似乎是树皮甲虫侵扰概率的重要预测指标。我们得出的结论是，将天顶作为一种简单的方法来定义被砍伐树木在地形上的位置，可以预见甲虫的侵扰。结论：我们的发现有助于了解主要风灾后最初几年树皮甲虫在被风吹倒的树木上定殖的偏好。此外，我们的发现可以帮助确定最容易受到甲虫侵扰的树木，并确定管理措施的优先次序，以在保持生物多样性的同时控制甲虫种群。