Can rDNA analyses of diverse fungal communities in soil and roots detect effects of environmental manipulations—a case study from tallgrass prairie

Abstract

We tested whether fungal communities are impacted by nitrogen deposition or increased precipitation by PCR-amplifying partial fungal rRNA genes from 24 soil and 24 root samples from a nitrogen enrichment and irrigation experiment in a tallgrass prairie at Konza Prairie Biological Station in northeastern Kansas, U.S.A. Obtained fungal sequences represented great fungal diversity that was distributed mainly in ascomycetes and basiodiomycetes; only a few zygomycetes and glomeromycetes were detected. Conservative extrapolated estimates of the fungal species richness suggest that the true richness may be at least twice as high as observed. The effects of nitrogen enrichment or irrigation on fungal community composition, diversity or clone richness could not be unambiguously assessed because of the overwhelming diversity. However, soil communities differed from root communities in diversity, richness and composition. The compositional differences were largely attributable to an abundant, soil-inhabiting group placed as a well-supported sister group to other ascomycetes. This group likely represents a novel group of fungi. We conclude that the great fungal richness in this ecosystem precluded a reliable assessment of anthropogenic impacts on soil or rhizosphere communities using the applied sampling scheme, and that detection of novel fungi in soil may be more a rule than an exception.

• Fungi
• soil DNA
• environmental change
• precipitation
• nitrogen
• biodiversity

This study was partially funded by National Science Foundation (DEB-0344838 to AJ). The irrigation transects were maintained by Konza Prairie Biological Station and funded by National Science Foundation Long Term Ecological Research program. Daniel Neises and Emily King assisted in the screening of the clone libraries. Dr. John F. Walker assisted with the jackknife estimators to obtain extrapolated species diversity. Earlier drafts of the manuscript were improved by the helpful comments from Charles Kramer, Nick Simpson and John F. Walker.