The role of decaying logs in nursing soil fungal diversity varies with decay classes in the forest ecosystem.

Soil fungi are crucial drivers of log decomposition in forest ecosystems, but how soil fungal community composition varies during the process of log decomposition remains poorly understood. We conducted an experiment incubating decaying logs in a subalpine coniferous forest on the eastern Qinghai‐Tibet Plateau, China. Five classes of decaying Minjiang fir (Abies faxoniana) logs were incubated on the forest floor, and the composition and diversity of fungal communities in soils underneath decaying logs were measured using high‐throughput sequencing. A total of 4321 operational taxonomic units (OTUs) were detected by Illumina NovaSeq sequencing analysis. Soil fungal diversity differed significantly during the process of log decomposition and was highest in decay classes III or IV. Basidiomycota and Ascomycota were dominant phyla regardless of log decay classes. Moreover, the proportion of arbuscular mycorrhiza, wood saprotroph and saprotrophs increased during the process of log decomposition, but that of ectomycorrhiza decreased. The structure of soil fungal community underneath decaying logs varied greatly with decay classes. Different decay classes of logs favour special fungal groups, implying that the ecological effects of logs at differing decay classes on soil fungal communities were different. Highlights: Effects of logs at differing decay classes on soil fungal community were different.Soil fungal diversity was highest in decay classes III or IV.Basidiomycota and Ascomycota were dominant phyla regardless of decay classes.Soil fungi groups on guilds and relative abundance of genera differed by decay classes. [ABSTRACT FROM AUTHOR]