Oak wilt disease may reduce the initial decay rate of dead Quercus serrata stems by altering wood-inhabiting fungal communities

Oak wilt causes severe dieback of Quercus serrata, a dominant tree species
in the lowlands across Japan. Here, we evaluated the effects of oak wilt
on the wood-inhabiting fungal community and the decay rate of deadwood
using a field monitoring experiment. We demonstrated the fungal
metabarcoding community from 1147 wood samples obtained from 120
experimental logs from three forest sites at five different time points
during the initial 1.5 years of the experiment. Death due to wilt
significantly influenced the fungal community composition and reduced
fungal diversity, probably due to the dominance of a limited number of
species. The Operational taxonomic unit (OTU) richness, occurrence
frequency, and DNA copy number of white rot fungi were also enhanced on
the logs killed by wilt, depending on the sites. Structural equation
modeling suggested that the wilt-initiated changes in the fungal community
reduced the decay rate of oak logs. Temperature and wood moisture also
affected the fungal community and log decomposition. These results
suggested that, in addition to the direct effect of climate, oak wilt
indirectly affects log decomposition via structuring fungal community.
Continuous monitoring is essential to evaluate the longer-term effects of
oak wilt on the fungal decomposition of wood.