Temporal distance decay of similarity of ectomycorrhizal fungal community composition in a subtropical evergreen forest in Japan.

Community compositions of ectomycorrhizal (ECM) fungi are known to show spatial distance decay of similarity, which arises from both deterministic niche-based processes and stochastic spatial-based processes (e.g. dispersal limitation). Recent studies have highlighted the importance of incorporating the spatial-based processes in the study of community ecology of ECM fungi. However, few studies have investigated the temporal distance decay of similarity of ECM fungal communities. More specifically, the role of stochastic temporal-based processes, which could drive the temporal distance decay of similarity independently of niche-based processes, in the temporal variation of the communities remains unclear. Here we investigated ECM fungi associated with roots of Castanopsis sieboldii at 3-month intervals over a 2-year period. We found that dissimilarity of the ECM fungal community composition was significantly correlated with temporal distance but not with environmental distance among sampling dates. Both climatic and temporal variables significantly explained the temporal variation of the community composition. These results suggest that temporal variations of ECM fungi can be affected not only by niche-based processes but also by temporal-based processes. Our findings imply that priority effects may play important roles in the temporal turnover of ECM fungal community at the site.
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