Restoration of natural legacies of fire in European boreal forests: an experimental approach to the effects on wood-decaying fungi

Effective fire suspension in Fennoscandian boreal forests has caused a number of species to become threatened. To compensate for the negative ecological impacts of fire elimination, prescribed burning of forests as a restoration method has been introduced recently. We studied the effects of controlled burning on assemblages of wood-decaying polypores (Basidiomycota), including red-listed species, in a large-scale field experiment in Finland. A total of 24 forest sites were included in the factorial study design with two factors: logging and burning. The presence of polypore fruiting bodies was documented 1 year before the treatments, and 1 and 4 years after the treatments. Over 11 000 observations of 104 species of polypores were made. Change in the fungal species composition due to logging and burning was clear after 4 years. At the species level, the responses to logging and fire varied depending on the species. Treatments increased fruiting of pioneer decayers; however, most red-listed species seemed to suffer. Thus, prescribed burning does not offer immediate benefits for most red-listed species. In unlogged forests, the restorative effects of fire are likely to be seen later as the death and decay processes of trees continue and provide more resources for polypores.