Short communicationHow does the richness of wood-decaying fungi relate to wood microclimate?

- The number of non-red-listed species was negatively related to extreme temperatures.
- Species numbers were related to the frequency and rate of temperature fluctuations.
- Different microclimate variables related to red-listed versus non-red-listed species.

Microclimatic conditions in dead wood influence fungal growth and hence also species composition, but it remains unclear how they influence species richness in nature. We analysed fungal species richness based on the occurrence of fruit bodies on 2 m long segments of both standing and lying trunks of Norway spruce (Picea abies). The number of non-red-listed species was related positively to moisture, and negatively to both temperature extremes and fluctuations. The numbers of both red-listed and non-red-listed species were further differently influenced by trunk diameter and by trunk properties related to the progression in wood decay. These results indicate that the richness of fungal communities in dead wood is shaped by an interaction of wood decay, moisture and temperature fluctuations.