Patterns of fungal communities among and within decaying logs, revealed by 454 sequencing

Abstract

Owing to previous methodological limitations, knowledge about the fine‐scale distribution of fungal mycelia in decaying logs is limited. We investigated fungal communities in decaying Norway spruce logs at various spatial scales at two environmentally different locations in Sweden. On the basis of 454 pyrosequencing of the ITS 2 region of rDNA, 1914 operational taxonomic units (OTU s) were detected in 353 samples. The communities differed significantly among logs, but the physical distance between logs was not found to have a significant effect on whether fungal communities had any resemblance to each other. Within a log, samples that were closer together generally had communities that showed more resemblance to each other than those that were further apart. OTU s characteristic for particular positions on the logs could be identified. In general, these OTU s did not overlap with the most abundant OTU s, and their ecological role was often unknown. Only a few OTU s were detected in the majority of logs, whereas numerous OTU s were rare and present in only one or a few logs. Wood‐decaying B asidiomycetes were often represented by higher sequence reads in individual logs than A scomycete OTU s, suggesting that B asidiomycete mycelia spread out more rapidly when established. OTU richness tended to increase with the decay stage of the sample; however, the known wood decayers were most abundant in less‐decomposed samples. The fungi identified in the logs represented different ecological strategies. Our findings differ from previously published sporocarp studies, indicating that the highly abundant fruiting species may respond to environment in different ways than the rest of the fungal community.