Diverse ecological roles within fungal communities in decomposing logs of Picea abies

Abstract

Fungal communities in Norway spruce (Picea abies) logs in two forests in Sweden were investigated by 454-sequence analyses and by examining the ecological roles of the detected taxa. We also investigated the relationship between fruit bodies and mycelia in wood and whether community assembly was affected by how the dead wood was formed. Fungal communities were highly variable in terms of phylogenetic composition and ecological roles: 1910 fungal operational taxonomic units (OTUs) were detected; 21% were identified to species level. In total, 58% of the OTUs were ascomycetes and 31% basidiomycetes. Of the 231 337 reads, 38% were ascomycetes and 60% basidiomycetes. Ecological roles were assigned to 35% of the OTUs, accounting for 62% of the reads. Wood-decaying fungi were the most common group; however, other saprotrophic, mycorrhizal, lichenized, parasitic and endophytic fungi were also common. Fungal communities in logs formed by stem breakage were different to those in logs originating from butt breakage or uprooting. DNA of specific species was detected in logs many years after the last recorded fungal fruiting. Combining taxonomic identification with knowledge of ecological roles may provide valuable insights into properties of fungal communities; however, precise ecological information about many fungal species is still lacking.