The effect of forest fuel harvesting on the fungal diversity of clear-cuts

The removal of logging residues and stumps from clear-cuts has become a common forestry practice. Forest fuel harvesting decreases the initially low volume of dead wood in managed forests, but the biodiversity effects are poorly known. We studied the effects of forest fuel harvesting on decomposer fungi on clear-cut Norway spruce stands in central Finland. The number of occurrences and taxa of polypores, saprotrophic agarics and pleurotoid agarics were determined on 10 forest fuel harvested and 10 control clear-cuts 4–5 years after logging. In total, we recorded 148 fungal taxa. The total number of taxa, the number of polypore occurrences, and the number of polypore species within small area were lower at forest fuel harvested sites. The effect on the number of saprotrophic agaric taxa became obvious with increasing area. Most of the common polypore species had fewer occurrences on forest fuel harvested sites while the commonest agaric species increased due to forest fuel harvesting. Concerning different dead wood types, there were fewer fungal species and occurrences on stumps and fewer occurrences on logs on forest fuel harvested sites. Most of the effects of forest fuel harvesting were explained by the reduction in resource availability. We conclude that forest fuel harvesting, especially stump removal, has negative effects on decomposer fungi and that there is a risk that populations of certain species still thriving in managed forests will decline in the future.

► We studied the effects of forest fuel harvesting on forest fungi.
► We compared forest fuel harvested clear-cuts to control clear-cuts.
► Harvesting decreased the number of decomposer fungi.
► Especially stump removal had strong negative effects.
► Harvesting benefited some disturbance-favouring species.