Phellinus nigrolimitatus—a wood-decomposing fungus highly influenced by forestry

Abstract

In this study, we document the habitat (substrate) requirements of the red-listed fungus Phellinus nigrolimitatus and assess the effect of forest management (forest age, amount of dead wood), climatic zone, topography, forest type, and site productivity on the occurrence of this fungus. We investigated 159 sample sites with different histories of logging activity, in four climatic zones in SE Norway and recorded the fungus on 93 out of 4146 inspected logs in 33 of the 159 sites. The fungus was clearly most frequent on Picea abies (5.8%) but we also found it on five Pinus sylvestris logs (0.4%). The frequency of the species depended highly upon the decay class and diameter of the logs. We never found P. nigrolimitatus on recently dead logs and only once on a weakly decayed log. The frequency increased sharply on moderately decayed logs and even further on very decayed logs. We rarely found the species on small spruce logs, but found it on nearly a quarter of spruce logs in the diameter class >40 cm. P. nigrolimitatus exhibited a clear trend in being more frequent on spruce logs in highly productive sites compared to logs in sites of medium and low productivity. Furthermore, P. nigrolimitatus showed a clear trend in being systematically more frequent from young to old-growth forest. When we related the frequency directly to the forest management history, as defined by the coarse woody debris profile, it turned out that the fungus was found on 35% of the suitable logs in the stands that had been unmanaged for several tree generations, while it was found on 4–9% of the suitable logs in managed forests. We found an average frequency reduction of 82% from natural forests to managed forests when we compared similar substrates. This frequency reduction in combination with reduced substrate availability suggests a population decline larger than 95% from the period before widespread logging, several centuries ago, until today.