In this era of biodiversity loss and climate change, quantifying the impacts of natural disturbance on forest communities is imperative to improve biodiversity conservation efforts. Epiphytic and epixylic lichens are effective forest quality bioindicators, as they are generally long-lived organisms supported by continuity of specific forest structures and their associated microclimatic features. However, how lichen communities respond to the effects of fluctuating historical disturbances remains unclear. Using a dendrochronological approach, this study investigates how natural disturbance dynamics indirectly influence various lichen community metrics in some of Europe's best-preserved primary mixed-beech forests. Mixed modelling revealed that natural historical disturbance processes have decades-long effects on forest structural attributes, which had both congruent and divergent impacts on lichen community richness and composition. Total species richness indirectly benefited from both historical and recent higher-severity disturbances via increased standing dead tree basal area and canopy openness respectively - likely through the presence of both pioneer and late-successional species associated with these conditions. Red-listed species richness showed a dependence on habitat continuity (old trees), and increased with disturbance-related structures (standing dead trees) whilst simultaneously benefiting from periods without severe disturbance events (old trees and reduced deadwood volume). However, if the disturbance occurred over a century in the past, no substantial effect on forest structure was detected. Therefore, while disturbance-mediated forest structures can promote overall richness, threatened species appear vulnerable to more severe disturbance events – a concern, as disturbances are predicted to intensify with climate change. Additionally, the high number of threatened species found reinforce the critical role of primary forest structural attributes for biodiversity maintenance. Hence, we recommend a landscape-scale conservation approach encompassing forest patches in different successional stages to support diverse lichen communities, and the consideration of long-term disturbance dynamics in forest conservation efforts, as they provide critical insights for safeguarding biodiversity in our changing world.

中文翻译：

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维持森林生物多样性：探索长期自然干扰动态对原始森林生态系统中当代地衣群落的影响


在这个生物多样性丧失和气候变化的时代，量化自然干扰对森林群落的影响对于改善生物多样性保护工作势在必行。附生和附生地衣是有效的森林质量生物指标，因为它们通常是长寿的生物体，由特定森林结构的连续性及其相关的小气候特征支持。然而，地衣群落如何应对历史动荡的影响仍不清楚。本研究采用树木年代学方法，调查了自然扰动动态如何间接影响欧洲一些保存最完好的原始混合山毛榉林中的各种地衣群落指标。混合模型表明，自然历史扰动过程对森林结构属性具有长达数十年的影响，这对地衣群落的丰富度和组成既有一致的影响，也有不同的影响。总物种丰富度间接受益于历史和最近更严重的干扰，分别通过增加直立死树的基础面积和树冠开放度 - 可能是通过与这些条件相关的先驱和晚期演替物种的存在。红色名录物种丰富度显示出对栖息地连续性（老树）的依赖，并随着与干扰相关的结构（站立的死树）而增加，同时受益于没有严重干扰事件的时期（老树和减少的枯木体积）。然而，如果干扰发生在一个多世纪以前，则没有检测到对森林结构产生实质性影响。 因此，虽然干扰介导的森林结构可以促进整体丰富度，但受威胁的物种似乎容易受到更严重的干扰事件的影响——这是一个令人担忧的问题，因为预计干扰会随着气候变化而加剧。此外，发现的大量受威胁物种强化了原始森林结构属性对于维持生物多样性的关键作用。因此，我们建议采用景观规模的保护方法，包括不同演替阶段的森林斑块，以支持不同的地衣群落，并考虑森林保护工作中的长期干扰动态，因为它们为在不断变化的世界中保护生物多样性提供了重要的见解。