Impact of harvesting intensity on wood-inhabiting fungi in boreal aspen forests of Eastern Canada

Environmental change, including human disturbance, can have a striking impact on the biodiversity of ecosystems. We used a molecular fingerprinting technique to determine how communities of saproxylic fungi on trembling aspen deadwood change under the influence of silvicultural treatments designed to emulate natural stand dynamics. We describe changes in richness, diversity, and species composition of fungal communities of trembling aspen logs and snags caused by these silvicultural practices. Our study was conducted in the SAFE Project, a series of silvicultural experiments that tests an ecosystem management model based on natural dynamics. We found that large trembling aspen logs and in advanced decay stages had approximately 9% higher fungal species richness and 10% higher fungal diversity than small and large logs at medium decay stages. The effect of log diameter was in turn strongly dependent on the silvicultural treatment. In burned stands, larger logs supported higher fungal richness and diversity, therefore potentially acting as fungal refuge. A negative relationship between the fungal diversity of logs and snags and the volume of fine woody debris was also related to silvicultural treatments, as fine woody debris increased with silvicultural intensity. Our results underline the negative effects of intense silvicultural practice on fungal diversity and species richness by modifying community composition, but they also highlight the benefits of partial harvest, which retain coarse woody debris volume.

► Large and well-decayed logs increase the species diversity of saproxylic fungi.
► High FWD volumes after harvesting decrease logs and snags fungal diversity.
► Large logs act as refuge for fungi in burned stands compared to uncut stands.
► Partial-cutting maintain CWD volume vs. FWD compared to even-age treatments.
► Partial-cutting seems to be a reasonable approach to ecosystem management of fungi.