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Questions: In production forest landscapes, threatened species are increasingly confined to fragments of natural forest. Protecting such fragments is a priority to halt further biological degradation, but its effectiveness depends on external impacts on the fragments. In this study, we ask: how does woody vegetation in protected old-forest fragments vary depending on management of their adjacent areas, also in combination with natural site conditions? What are the management impacts on habitat quality of the fragments in the long term? Location: Pinus-dominated and Picea mixed-wood forests in Estonia (hemiboreal Europe). Methods: Forest structure and microclimate were measured at the edge and interior of protected old-forest fragments. Woody vegetation layers, shrub species composition, coarse woody debris, and presence of cut stumps were measured in 107 fragments (adjacent to clearcuts, partial cuts, and unthinned production forests) and in 20 control stands embedded within natural forest. Air temperature and humidity were measured at the edges vs the interior of mixed-woods. Edge age effects were explored along 80 years of post-harvest chronosequences. Results: All edge types studied had multiple, partly forest-type-specific, external effects on stand structure. Some clear-cutting effects on woody layers reversed in later decades, but there was also persistent impoverishment of deadwood pools of the fragments probably related to unreported tree removal. There was a likely indirect pathway of edge effects through overstorey loss, and shrub cover was reduced in the long term. Exotic species were rare. Edges at clear-cut stands influenced humidity regimes rather than temperature regimes. Conclusions: The moderate external effects on stand structure were tightly linked to low overstorey mortality and a lack of exotic species across the forest landscapes studied. Changes in these key factors constitute risks for the future. Protecting setasides from occasional tree cutting, and establishing forest buffers around small fragments and as a precautionary strategy are current priorities in these forest landscapes. [ABSTRACT FROM AUTHOR]

A major question in fungal conservation is why many species are confined to old forests, and how they could be supported by contemporary landscape matrix. Specifically, forestry that retains large biological legacies across landscape could reduce old-forest dependencies to species that require unusual substrate conditions. We sampled polypores in 112 2 ha plots (both old and harvested stands) in a semi-natural forestry context in Estonia and modelled the habitat factors of species confined to old growth. The results confirmed that old-growth assemblages emerged mostly due to diverse and abundant substrate supply (notably downed CWD). Only 10 species (five spruce-dwellers) were confined to old growth; of these, only Fomitopsis rosea and Oxyporus corticola were additionally affected by forest connectivity. The forestry system studied appeared particularly favourable for the species inhabiting deciduous wood. To better address habitat degradation in conservation, expert lists of ‘old-forest (indicator) fungi’ should be replaced with evidence-based focal taxa. [ABSTRACT FROM AUTHOR]

• We measure the habitat relationships of wood-inhabiting fungi using DNA metabarcoding. • Old stands had larger species pools, at the landscape but not at the trunk scale. • High landscape-scale forest cover supported trunk scale fungal richness. • Increase in local dead-wood volume increased number of red-listed species per trunk. • Conservation conclusions based on DNA in wood same as in former fruit-body surveys. Understanding the distribution of biodiversity across forest landscapes is a key issue for the spatial planning of conservation management. Obtaining such spatial perspective is challenging because a large part of biodiversity remains hidden to the conventional survey approaches. High-productivity forests are probably the hotspots of hidden biodiversity and, at the same time, under severe timber harvesting pressure. We used DNA-metabarcoding approach to assess habitat quality of successional high productivity forests for wood-inhabiting fungi, focusing on fungal diversity that remains hidden in fruit-body surveys. We sampled a fixed amount of coarse fallen Norway spruce trunks in 40 naturally developing stands ranging from 44 to 140 years of age in hemi-boreal Estonia. We found three main habitat quality patterns. The total number of fungal OTUs in older (>80 years) stands exceeded that in younger stands due to the accumulation of rare fungi. The proportion of trunks hosting highest number of OTUs and trunk-scale richness of rare fungi were greatest in stands surrounded by extensive forest area. The average number of red-listed species per trunk increased mainly along with the volume of fallen dead wood; large volumes provided quality habitats already before the stands had reached 80 years of age. These results support the view that both substrate amount in the forest stand and habitat connectivity on a landscape scale support fungal diversity in dead wood. Earlier studies on wood-inhabiting fungi have reached similar conclusions based on observations of fungal fruit-bodies. Thus, the overall principle of focusing conservation efforts to remaining high quality habitats and landscapes extends to the fungi hidden to the conventional survey methods. [ABSTRACT FROM AUTHOR]