Leclerc Marc-Antoine, Simard Martin, Morin Hubert
Department of Fundamental Sciences, Université du Québec à Chicoutimi, Chicoutimi, Québec, Canada.
Department of Geography, Université Laval, Québec City, Québec, Canada.
PLoS One. 2025 Aug 12;20(8):e0329406. doi: 10.1371/journal.pone.0329406. eCollection 2025.
Applying a centennial or millennial perspective to disturbance regimes permits an understanding of how these events have varied in the past in relation to climate change. Correctly interpreting this variability is crucial when preparing sustainable forest management practices for future warming. The eastern spruce budworm (Lepidoptera) is the most important biotic disturbance in the eastern Canadian boreal forest. Adult moths are covered by chitinous scales, and lepidopteran scale records in lake sediments have been analyzed to reconstruct Holocene spruce budworm populations. However, the magnitude of these scale accumulations has yet to be calibrated using an independent proxy. Here, we determine whether the impacts of spruce budworm defoliation are recorded by both sedimentary lepidopteran scale accumulations and tree-ring widths. Agreement between proxies was found at five of nine sites and strongest between the proportion of affected trees and scale accumulations while agreement in signal synchronicity was found at six of nine sites and strongest when comparing scale accumulations to a growth suppression index. A species-based composite chronology relying on white spruce produced the clearest outbreak record for both proxy records. Peak scale accumulations correlated well with smaller tree-ring widths, demonstrating that larger scale accumulations correspond to more severe defoliation events. Therefore, lepidopteran scales provide reliable records of spruce budworm abundance serving as a proxy record ameliorating our understanding of how budworm impacts have fluctuated at centennial and millennial time scales in the context of past climate change.
从百年或千年的视角来看待干扰动态，有助于理解这些事件在过去如何随气候变化而变化。在为未来变暖制定可持续森林管理实践时，正确解读这种变异性至关重要。东部云杉芽虫（鳞翅目）是加拿大东部北方森林中最重要的生物干扰因素。成年蛾覆盖着几丁质鳞片，人们已对湖泊沉积物中的鳞翅目鳞片记录进行分析，以重建全新世云杉芽虫种群。然而，这些鳞片积累的规模尚未通过独立的代理指标进行校准。在此，我们确定云杉芽虫落叶的影响是否通过沉积的鳞翅目鳞片积累和树木年轮宽度来记录。在九个地点中的五个地点发现了代理指标之间的一致性，受影响树木比例与鳞片积累之间的一致性最强，而在九个地点中的六个地点发现了信号同步性的一致性，将鳞片积累与生长抑制指数进行比较时一致性最强。基于白云杉的物种综合年表为两个代理记录产生了最清晰的爆发记录。鳞片积累峰值与较小的树木年轮宽度相关性良好，表明更大的鳞片积累对应更严重的落叶事件。因此，鳞翅目鳞片提供了云杉芽虫丰度的可靠记录，作为一种代理记录，有助于我们更好地理解在过去气候变化背景下，芽虫影响在百年和千年时间尺度上是如何波动的。
