Relationship between the decomposition process of coarse woody debris and fungal community structure as detected by high-throughput sequencing in a deciduous broad-leaved forest in Japan. wood decay metagenome

We examined the relationship between the community structure of wood-decaying fungi detected by high-throughput sequencing and the decomposition rate by using 13 years of data from a forest dynamics plot. For molecular analysis and wood density measurements, drill dust samples were taken from logs and stumps of Fagus and Quercus in the plot. Regression using a negative exponential model between wood density and time since death revealed that the decomposition rate of Fagus was faster than that of Quercus. The residual between the expected value obtained from the regression curve and the observed wood density was used as a decomposition rate index. Non-metric multidimensional scaling showed that fungal community compositions of both Fagus and Quercus changed with time since death. Non-metric multidimensional scaling axis scores were used as an index of fungal community composition. A structural equation model for each wood genus was used to test how strongly traits of the fungal community structure affected the decomposition rate and how the fungal community structure was determined by the traits of coarse woody debris. Results of the structural equation model suggested that the decomposition rate of Fagus was affected by community evenness and by two fungal community composition components: one that was affected by time since death and another not affected by environmental factors. In contrast, the decomposition rate of Quercus was not affected by environmental factors or fungal community structure. These findings suggest that, in the case of Fagus coarse woody debris, the fungal community structure is related to the decomposition process of its host substrate. Because fungal community structure is partly affected by the decay stage and wood density of its substrate, they affect each other interactively. Further research on interactive effects is needed to understand the relationship between fungal community structure and the woody debris decomposition process.