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 ITS2 region of rDNA, 1914 operational taxonomic units (OTUs) 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. OTUs characteristic for particular positions on the logs could be identified. In general, these OTUs did not overlap with the most abundant OTUs, and their ecological role was often unknown. Only a few OTUs were detected in the majority of logs, whereas numerous OTUs were rare and present in only one or a few logs. Wood-decaying Basidiomycetes were often represented by higher sequence reads in individual logs than Ascomycete OTUs, suggesting that Basidiomycete 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.

Linking molecular deadwood-inhabiting fungal diversity and community dynamics to ecosystem functions and processes in Central European forests

“…This is inconsistent with the findings of fructification pattern studies, which indicated that the abundance of fruiting bodies was highest at intermediate stages of decay (Heilmann-Clausen 2001; Hoppe et al 2014). However, the fact that fungal OTU richness increased with losses of mass and density (i.e., as the decay class increased) is in agreement with the results of previous studies on spruce deadwood that used molecular techniques (Kubartova et al 2012;Rajala et al 2012). The discrepancy between these findings may be due to the fact that many fungi tend to reside as vegetative mycelia in deadwood and therefore do not develop fruiting bodies (Kubartova et al 2012).…”

“…However, the fact that fungal OTU richness increased with losses of mass and density (i.e., as the decay class increased) is in agreement with the results of previous studies on spruce deadwood that used molecular techniques (Kubartova et al 2012;Rajala et al 2012). The discrepancy between these findings may be due to the fact that many fungi tend to reside as vegetative mycelia in deadwood and therefore do not develop fruiting bodies (Kubartova et al 2012). Only a small proportion of the sequences obtained from deadwood of Picea abies were assignable to Ascomycota, though the ratio of taxonomically assigned OTUs was balanced to Basidiomycota.…”

“…This work builds on earlier studies that used high-throughput sequencing to investigate fungal community structures in deadwood (Kubartova et al 2012;Ovaskainen et al 2013) by providing the first comparison of two morphologically The significance estimates were based on 999 permutations. Significant factors (Bonferroni corrected P<0.05) are indicated in bold.…”

“…In contrast, high-throughput sequencing allows for detailed analysis of community composition and may thus uncover a hitherto concealed fungal diversity residing in deadwood. This approach has been used to study WIF communities within and among Norway spruce (Picea abies) logs (Kubartova et al 2012) and to test the link between fungal life history and population dynamics (Ovaskainen et al 2013). As expected, these studies revealed much higher fungal species richness than previously published sporocarp surveys and suggested that highly abundant fruiting species may be only weakly representing the fungal community as a whole.…”

“…All of the European high-throughput sequencing based studies on WIF conducted to date focused on deadwood of either gymnosperm tree species, Picea abies, in a single biome, the boreal forest zone of Northern Europe (Kubartova et al 2012;Ovaskainen et al 2010Ovaskainen et al , 2013 or two angiosperm tree species, Fagus sylvatica and Quercus robur in temperate forests (Hiscox et al 2015;van der Wal et al 2015). Therefore, our information on community dynamics of WIF in deadwood of different tree species in the same forest ecosystem at different locations is still limited.…”