The natural and old-growth forests and their associated biodiversity continues to fade worldwide due to anthropogenic impact in various forms. The boreal forests in Fennoscandia have been subject to intensive clearfelling forestry since the middle of twentieth century. As a result, only a fraction of forests with long temporal continuity remains at the landscape level. In Sweden, some of these primary forests have been formally protected, whereas other forests with known high conservation values are not. Collectively, both protected and not protected known valuable primary forests are included in a nationally delineated network of high conservation value forests (HCVF). In addition to HCVF, older forests that have not been clearfelled since the mid-1900s, i.e., “proxy continuity forests,” have recently been mapped across the entire boreal biome in Sweden. In this paper, we analyze how these proxy continuity forests may strengthen the HCVF network from a green infrastructure perspective. First, we evaluate the spatial overlap between proxy continuity forests and HCVF. Second, we perform a large-scale connectivity analysis, in which we show that adding proxy continuity forests located outside HCVF strongly increases the structural connectivity of the network of protected forests. Finally, by assessing habitat suitability for virtual species specialized in pine, spruce, and broadleaf forests, we find large regional differences in the ability to secure habitat and thereby functional green infrastructure by considering currently unprotected primary forest. We show that, by adding those forests to the network, the area of habitat for low-demanding species dependent on spruce or pine forests can be largely increased. For high-demanding species, additional habitat restoration in the landscape matrix is needed. By contrast, even counting all valuable broadleaf forests available is not enough to provide a suitable habitat for their associated species, which indicates a large need for landscape-scale habitat restoration initiatives, in particular, for broadleaf forests.

中文翻译：

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加强北方地区高保护价值森林网络

由于各种形式的人为影响，天然和古老的森林及其相关生物多样性在全球范围内继续消退。自 20 世纪中叶以来，芬诺斯坎迪亚的北方森林一直受到密集的砍伐森林的影响。因此，只有一小部分具有长期时间连续性的森林保留在景观层面。在瑞典，其中一些原始森林已受到正式保护，而其他已知具有高保护价值的森林则没有。总体而言，受保护和未受保护的已知有价值的原始森林都包含在国家划定的高保护价值森林 (HCVF) 网络中。除了 HCVF，自 1900 年代中期以来没有被砍伐过的老森林，即“代理连续性森林，”最近在瑞典的整个北方生物群落中绘制了地图。在本文中，我们从绿色基础设施的角度分析了这些代理连续性森林如何加强 HCVF 网络。首先，我们评估代理连续性森林和 HCVF 之间的空间重叠。其次，我们进行了大规模的连通性分析，其中我们表明添加位于 HCVF 外部的代理连续性森林大大增加了受保护森林网络的结构连通性。最后，通过评估专门从事松树、云杉和阔叶林的虚拟物种的栖息地适宜性，我们发现通过考虑目前未受保护的原始森林，在保护栖息地的能力以及功能性绿色基础设施方面存在巨大的区域差异。我们表明，通过将这些森林添加到网络中，依赖云杉或松林的低要求物种的栖息地面积可以大大增加。对于高要求的物种，需要在景观矩阵中进行额外的栖息地恢复。相比之下，即使计算所有可用的有价值的阔叶林也不足以为其相关物种提供合适的栖息地，这表明非常需要景观规模的栖息地恢复计划，特别是阔叶林。