The role of novel forest ecosystems in the conservation of wood‐inhabiting fungi in boreal broadleaved forests

Abstract

The increasing human impact on the earth's biosphere is inflicting changes at all spatial scales. As well as deterioration and fragmentation of natural biological systems, these changes also led to other, unprecedented effects and emergence of novel habitats. In boreal zone, intensive forest management has negatively impacted a multitude of deadwood‐associated species. This is especially alarming given the important role wood‐inhabiting fungi have in the natural decay processes. In the boreal zone, natural broad‐leaved‐dominated, herb‐rich forests are threatened habitats which have high wood‐inhabiting fungal species richness. Fungal diversity in other broadleaved forest habitat types is poorly known. Traditional wood pastures and man‐made afforested fields are novel habitats that could potentially be important for wood‐inhabiting fungi. This study compares species richness and fungal community composition across the aforementioned habitat types, based on data collected for wood‐inhabiting fungi occupying all deadwood diameter fractions. Corticioid and polyporoid fungi were surveyed from 67 130 deadwood particles in four natural herb‐rich forests, four birch‐dominated wood pastures, and four birch‐dominated afforested field sites in central Finland. As predicted, natural herb‐rich forests were the most species‐rich habitat. However, afforested fields also had considerably higher overall species richness than wood pastures. Many rare or rarely collected species were detected in each forest type. Finally, fungal community composition showed some divergence not only among the different habitat types, but also among deadwood diameter fractions. Synthesis and applications: In order to maintain biodiversity at both local and regional scales, conserving threatened natural habitat types and managing traditional landscapes is essential. Man‐made secondary woody habitats could provide the necessary resources and serve as surrogate habitats for many broadleaved deadwood‐associated species, and thus complement the existing conservation network of natural forests.

Resource use of wood-inhabiting fungi in different boreal forest types

“…However, the dead wood profile does not seem to be the only determining factor explaining the differences in fungal communities among different forest types. For example, previously (Juutilainen et al 2016) we found that the dead wood profile did not explain why the fungal species richness and the number of rare species was relatively high in afforested fields compared to other habitats, even though the amount and diversity of dead wood in the afforested fields is very limited.…”

“…insperata, which was one of the most abundant species in afforested fields, but absent from every other forest type. This species was practically always found on small diameter birch wood (only one additional observation from unidentified deciduous wood), a substratum very common in all the deciduous forest types (Juutilainen et al 2016) and also present in all coniferous forests (Juutilainen et al 2014). It seems that some unknown factors play an additional role in the habitat selection of this and of other similar species.…”

“…Fine woody debris is a very abundant resource in most forest types (Juutilainen et al 2011, Juutilainen et al 2014, Juutilainen et al 2016) and its supply is continuous in most forests. Thus, specialization in finest woody debris could rationally be a winning evolutionary strategy.…”

“…The high level of specialization of species in afforested fields is a surprising result, as one may expect that only opportunistic species with wide niche are able to inhabit novel habitats. It may be that some specialists that we found in afforested fields are actually species associated with habitats our sampling did not include such as peatland forests, riverine/shore forests or shrub lands (see also discussion in Juutilainen et al (2016)). Therefore, to resolve the habitat requirements of the specialist species found in afforested fields requires that future studies should also encompass nonforest habitats in addition to the main forest types we studied.…”

“…The abundance data used in this paper combines the datasets of two earlier studies (Juutilainen et al 2014, Juutilainen et al 2016. The complete data comprises over 10 000 observations of woodinhabiting fungi, including species and genus level observations as well as unidentified specimens belonging to higher level taxa (Supplementary Appendix B).…”