Co-occurrence patterns of wood-decaying fungi on Picea abies logs: does Fomitopsis pinicola influence the other species?

Dominant fungi, especially primary decayers, probably influence other fungi growing together with them. Fomitopsis pinicola is one of the important primary decayers, and it has been shown that several other species regularly co-occur together with it. We asked whether the presence of common species (especially F. pinicola) affects the species richness and composition of other fungi. This study was conducted in an old-growth mountain spruce forest in the Bohemian Forest, Czech Republic. We surveyed logs on the ground for sporocarps of fungi in three successive years. Characteristics of logs such as dimensions, stage of decay and the cause of tree death (wind, competition, butt rot, bark beetles and unascertained) were recorded. F. pinicola was abundant mostly on logs that originated from trees infested by bark beetles. Analysis of covariance with the volume of logs and decay stage as covariables showed significant effect of these covariables and of F. pinicola presence on species numbers – logs in middle decay stages with the sporocarps of F. pinicola had more species than other logs. Based on Canonical Correspondence Analysis with volume, decay stage and the cause of tree death as covariables, the species composition on logs was also influenced by F. pinicola. We found such statistical effects in several other species. Redlisted species Antrodiella citrinella and Camarops tubulina co-occurred with F. pinicola.