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Appropriate conservation management of old-forest species depends on the causes of their old-forest affinity, which, however, are insufficiently known. Calicioid fungi are often considered old-forest dependent because of their special requirements for microhabitat, microclimate, and stand continuity for at least two tree generations. We demonstrate that, for several methodological or interpretational problems, published studies do not provide unequivocal evidence for such mechanisms and even for old-forest dependency of calicioids in general. We then analyse a large Estonian dataset (ca. 2300 records of 32 species) representing various management types and site types to answer whether old forests have more calicioid species, and any specific species, than could be expected for the substratum availability observed. Although old growth had more species and records than mature managed stands or cutover sites, those substratum types that occurred at roughly similar abundances also hosted comparable numbers of species in different management types. The characteristic substrata adding extra species to old growth were snags and root-plates of treefall mounds; wood surfaces in general comprised more than half of all calicioid records. Although substratum abundance did not fully explain the species-richness contrast between old growth and mature stands, additional evidence suggested that the unexplained variance is rather due to small-scale habitat characteristics than stand-scale continuity or microclimate. Finally, we review the evidence for old-forest affinity of calicioid species and distinguish a set of threatened species. We conclude that the availability of specific substrata is the main limiting factor for calicioid fungi in forests, and its quantitative and stochastic nature explains the large random and region-specific variation in the published lists of âold-forest speciesâ.

In navigating the biodiversity crisis, a major uncertainty is the conservation status of inconspicuous, yet megadiverse and functionally crucial, soil organisms. Massive datasets on soil biota are accumulating through molecular sampling approaches, but to date these datasets have provided only limited input into conservation planning and management. We investigated how environmental DNA (eDNA) data of soil macrofungi contribute to regional Red List assessments, which are currently based on fruiting bodies (hereafter, fruit‐bodies). In our test region of Estonia (northern Europe), which contained ~15,000 fruit‐body records for 1583 assessed species, an average soil sample increased the range estimates of Threatened and Near Threatened fungal species by 0.18%. Five hundred soil samples almost doubled their known localities and added 19% previously unrecorded species. However, even after accumulating >1000 soil samples, about half of the Threatened and Near Threatened species known by fruit‐bodies remained undetected through eDNA techniques. Effective conservation assessment of soil fungi thus requires both fruit‐body and eDNA data; therefore, special efforts are needed to make these data available to conservationists. [ABSTRACT FROM AUTHOR]

Fungal diversity drives key processes in terrestrial ecosystems, but remains challenging to measure in the field and to monitor over time. In particular, we lack methods capable of describing both the regional biotas and fungal related conservation values, such as habitats for rare and threatened fungi. Environmental DNA (eDNA) could serve this purpose, once its validity to capture fungal assemblage properties is established.Using three approaches (full‐season eDNA sampling from air, snapshot visual surveys, and eDNA sampling from dead wood), we present the first comparative assessment of fungal diversity at forest stand scale. The focus was on two well‐known fungal groups (lichens and wood inhabiting basidiomycetes) in old hemiboreal forests.Aerial eDNA revealed regional‐scale cryptic diversity not detected in visual surveys, particularly among lichens and including species of conservation concern. However, at the local population scale, both aerial eDNA and eDNA sampled from dead wood often missed visually detected species. In particular, eDNA sampled from dead wood performed only as a supplementary source of species data. The methods differed in detecting the spatial covariance of wood fungal and lichen diversity, with the combined (most complete) dataset indicating the strongest congruence.Synthesis and applications. Neither eDNA approaches nor visual surveys were able to detect full diversity of local fungi and all species of specific conservation value. However, there is clear merit in combined use of these methods, particularly in pairing aerial eDNA with visual observation‐based surveys on selected taxon groups. This approach can be especially valuable in fungal groups that have challenging taxonomy, inhabit partly inaccessible microhabitats, or have overall high diversity (such as lichens). [ABSTRACT FROM AUTHOR]

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