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

•Habitat and substrate specialization of 77 saproxylic fungal species was assessed.•High number of specialist species were associated with deciduous forest types.•Forest type specialists were also specialists for their substrate tree species.•Fungal preference for either large or small diameter substrate was evident.

Generalist species are usually widespread and abundant, and thrive in heterogeneous environments. Specialists, in turn, are generally more restricted in their range, and benefit from more stable conditions. Therefore, increasing human-induced disturbance can have more negative effects on specialist than generalist species. We assessed the specialization of 77 wood-inhabiting fungal species across seven boreal forest types and different substratum qualities. A significantly higher number of specialist species was associated with herb-rich forests and afforested fields than with managed coniferous forests and wood pastures, the number of specialists associated with natural coniferous forests being intermediate. Also, forest type specialists were indicated to be specialists for their substratum tree species as well, but specialization in substratum diameter was not connected with other kinds of specialization. Species with restricted resource or habitat preferences can less readily respond to environmental change, and therefore are more vulnerable to extinction.