Abstract Boreal and mountainous forests are a primary focus of conservation efforts and are naturally prone to large-scale disturbances, such as outbreaks of bark beetles. Affected stands are characterised by biological legacies which persist through the disturbance and subsequent succession. The lack of long-term monitoring data on post-disturbance forest structure precludes understanding of the complex pathways by which natural disturbances affect forest structure and subsequently species presence. We analysed the response of capercaillie (Tetrao urogallus) and hazel grouse (Tetrastes bonasia) to bark beetle infestations. We combined high-resolution airborne light detection and ranging (LiDAR) with a 23-year time series of aerial photography to quantify present-day forest structure and stand disturbance history. Species presence was assessed by collecting droppings of hazel grouse and capercaillie in a citizen science project. Structural equation models showed that the probability of hazel grouse presence increased with increasing disturbance, and the probability of both hazel grouse and capercaillie presence increased with succession. Indirect effects of bark beetle infestations, such as a reduced abundance of deciduous trees and an enhanced herb layer cover, were positively associated with capercaillie presence. Decreasing canopy cover increased the probability of hazel grouse presence. The high temporal and spatial heterogeneity of bark beetle infestations created forest structures that meet the contrasting habitat requirements of both, capercaillie and hazel grouse. This heterogeneity resulted from biological legacies such as decomposing snags, and the simultaneous regrowth of natural regeneration. A benign-neglect strategy towards bark beetle infestations could hence foster capercaillie and hazel grouse in mountainous forests.

中文翻译：

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自然干扰和早期演替后的森林结构为两种鸟类旗舰物种松鸡（Tetrao urogallus）和榛鸡（Tetrastes bonasia）提供了栖息地

摘要 北方和山地森林是保护工作的主要焦点，自然容易受到大规模干扰，例如树皮甲虫的爆发。受影响林分的特点是生物遗产在干扰和后续演替中持续存在。由于缺乏关于受干扰森林结构的长期监测数据，因此无法理解自然干扰影响森林结构和随后物种存在的复杂途径。我们分析了松鸡 (Tetrao urogallus) 和榛松鸡 (Tetrastes bonasia) 对树皮甲虫侵扰的反应。我们将高分辨率机载光探测和测距 (LiDAR) 与 23 年的航空摄影时间序列相结合，以量化当前的森林结构和林分干扰历史。通过在公民科学项目中收集榛鸡和松鸡的粪便来评估物种的存在。结构方程模型表明，榛子松鸡出现的概率随着干扰的增加而增加，榛子和松鸡出现的概率依次增加。树皮甲虫侵染的间接影响，例如落叶树的丰度减少和草本层覆盖率的增加，与松柏的存在呈正相关。减少树冠覆盖增加了榛松鸡出现的可能性。树皮甲虫侵扰的高度时空异质性创造了满足松鸡和榛鸡两种不同栖息地要求的森林结构。这种异质性是由生物遗产造成的，例如分解的障碍物，以及自然再生的同时再生。因此，针对树皮甲虫侵扰的良性忽视策略可能会在山区森林中培育松鸡和榛鸡。