Forest harvesting changes forest habitat and impacts forest dependent species. Uneven-aged management is often considered better for biodiversity than even-aged management, but there is an ongoing discourse over the benefits and disadvantages of different silvicultural systems. This systematic review contributes to the public discussion and provides evidence for policy making by synthesising current evidence on impacts of even-aged and uneven-aged forest management on biodiversity in boreal forests of Fennoscandia and European Russia. In this review even-aged and uneven-aged forest management are compared directly to each other as well as to natural forest to provide a broad basis for public discussion. Both peer-reviewed and grey literature were searched in bibliographical databases, organizational webpages and internet search engines in English, Finnish, Swedish and Russian. Articles were screened for relevance by their title/abstract and again by full text. The inclusion of studies was assessed against pre-defined criteria published in an a priori protocol. A narrative synthesis and meta-analysis were conducted to describe the evidence base and to compare species richness and abundance between differently managed forests. The influence of habitat specialism, taxon, years since harvesting, deadwood availability and harvesting intensity on species richness and abundance were also tested. Searching identified 43,621 articles of which 137 articles with 854 studies had independent data and were included in the narrative synthesis. Of those, 547 studies were included in the meta-analysis. The most studied taxa were arthropods, vascular plants, bryophytes, fungi, and lichens. Results showed that forests with less disturbance (uneven-aged and mature even-aged) host more forest dependent species than young even-aged forests (< 80 years old) although the difference was only marginally significant for mature even-aged forests (> 80 years old). Uneven-aged forest had similar number of species and individuals than natural forest whereas even-aged forest had less species than natural forest. Open habitat species and their individuals were more numerous in young even-aged forests and forests undergone retention harvest. Effect sizes found were mostly large indicating strong and uniform impact of forest management based on species’ habitat preferences. In addition to habitat specialism, years since harvest explained some of the differences found in species richness and abundance due to increase of open habitat species in the early successional stages and forest dependent species in late successional stages. Taxon had limited explanatory power. Habitat preferences determine species’ response to different harvesting methods and the magnitude of effect is large. Less disturbance from harvesting is better for forest dependent species whereas opposite is true for open habitat species. Uneven-aged and mature even-aged forests (> 80 years old) are important to maintain biodiversity in boreal forests. However, the results also highlight that natural forests are needed to ensure the future of forest dependent species in Fennoscandia and European Russia. Given that a broader set of biodiversity aspects are to be protected, best overall biodiversity impacts for a variety of species at landscape level can be achieved by ensuring that there is a mosaic of different forests within landscapes.

中文翻译：

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芬诺斯堪的亚和欧洲俄罗斯的均匀和不均匀森林管理对北方森林生物多样性有什么影响？系统评价

森林采伐改变了森林的栖息地并影响了森林依赖物种。人们通常认为，不均衡管理对于生物多样性要比均衡管理更好，但是关于不同造林系统的利弊的讨论仍在进行中。这项系统的审查有助于公众讨论，并通过综合有关均匀年龄和不均匀年龄森林管理对芬诺斯堪的亚和欧洲俄罗斯北方森林生物多样性的影响的现有证据，为决策提供证据。在这篇综述中，将平均年龄和不均匀年龄的森林管理直接相互比较，并与天然林进行了比较，为公众讨论提供了广阔的基础。在书目数据库，组织网页和互联网搜索引擎中，通过英语搜索了同行评审和灰色文献，芬兰文，瑞典文和俄文。通过文章的标题/摘要和全文来筛选文章的相关性。根据先验方案中发布的预定义标准评估研究的纳入。进行了叙述性综合和荟萃分析，以描述证据基础并比较不同管理的森林之间物种的丰富度和丰度。还测试了栖息地专长，分类单元，收获以来的年限，枯木的可利用性和收获强度对物种丰富度和丰度的影响。检索确定了43,621篇文章，其中137篇文章进行了854项研究，这些文章具有独立数据，并包含在叙述性综合中。在这些研究中，有547项研究被纳入荟萃分析。研究最多的类群是节肢动物，维管植物，苔藓植物，真菌和地衣。结果表明，干扰程度较小的森林（不均匀年龄和成熟的均匀年龄）比年轻的均匀年龄森林（<80岁）拥有更多的依赖森林的物种，尽管对于成熟的均匀年龄森林（> 80）而言，差异仅是很小的。岁）。高龄林的物种和个体数量与天然林相似，而高龄林的物种和个体数量少于天然林。在年轻的均匀老龄森林中，开放栖息地物种及其个体数量更多，并且森林经历了保留采伐。发现的影响大小大多很大，表明基于物种生境偏好的森林管理具有强大而统一的影响。除了栖息地专长之外，采伐以来的多年解释了物种丰富度和丰度方面的一些差异，这是由于在演替初期开放的栖息地物种增加以及在演替后期增加了依赖森林的物种。分类单元的解释力有限。生境的偏好决定了物种对不同收获方式的反应，其影响程度很大。较少的采伐干扰对依赖森林的物种更好，而对开放生境物种则相反。不平均年龄和成熟的平均年龄森林（> 80年历史）对于维持北方森林的生物多样性很重要。但是，结果还强调，需要天然森林来确保芬诺斯坎迪亚和欧洲俄罗斯的森林依赖物种的未来。鉴于将保护更广泛的生物多样性方面，