Although fungi are important decomposers in lotic environments, few studies have investigated the spatial and temporal changes in epilithic fungal communities in rivers. If epilithic organisms grow using organic matter and nutrients ultimately discharge into rivers, it is likely that the taxonomic composition of epilithic fungal communities will change spatially depending on the land use and land cover (LULC) in the drainage area. To test this hypothesis, we examined the relationship between the taxonomic composition of fungi on cobbles and the LULC in the fall and in spring. The taxonomic composition of the epilithic fungi was significantly related to ambient water temperatures and concentrations of nutrients and dissolved organic carbon. Supporting our hypothesis, the taxonomic composition of the epilithic fungi differed largely among the reaches covered mainly by different forest types and land uses in both the fall and in spring. The results suggest that the quality of the dissolved organic matter differed among the catchment areas depending on the LULC. Further analyses indicated that the sum of the LULC and within-river variables could explain 36.4 and 41.2 % of the spatial variation in the fungal taxonomic compositions in the fall and in spring, respectively. The LULC variables alone explained 16.1–18.7 % of the variations, and a similar percentage was found for within-river variables. These results suggest that the organic matter from LULC was equally as important as physical and nutrient conditions in the ambient water for determining the community structure of epilithic fungi in rivers.
ASJC Scopus subject areas