Is it climate or chemistry? Soil fungal communities respond to soil nutrients in a multi-year high-resolution analysis

Abstract

Predicting potential responses of soil fungal communities and fungal diversity to environmental change is limited by relatively few long-term data sets, despite the important role fungi play in ecosystem processes. In this study, we examined the relative importance of environmental factors (weather or climate factors and chemical factors) on fungal communities over a period of five years. We examined fungal communities in an old-growth beech-maple forest in northeastern Ohio, located within the snow belt of Lake Erie, which receives an average of 287 cm of snowfall. Soil was collected every month from long-term plots and divided into different soil depths; a total of 1080 samples were collected and used for fungal community and chemical analysis. We used DNA fragment analysis methods to examine fungal community response to environmental factors, and used next-generation sequencing to examine specific responses of fungal species and quantify diversity in forest soil. Tests for phylogenetic signal were used to explore whether fungal responses are similar among close relatives or divergent within clades. Fungal communities responded significantly to chemical factors such as soil phosphorus but responded weakly to climate factors such as soil temperature, suggesting that fungal community composition reflects temporal variation in microsite environmental conditions. Sequencing revealed high degrees of fungal species richness, with an average of 384 operational taxonomic units (OTUs) within each soil core and more than 1000 OTUs within our study site. Fungal taxa associated with phosphorus availability and soil moisture were also distributed broadly across fungal clades (e.g., Basidiomycota, Ascomycota). Our study suggests that microsite chemical factors (e.g., soil moisture, P availability) correlate more strongly with fungal community variation than climate factors (e.g., soil temperature). In addition, environmental responses were not conserved among close relatives, suggesting that relatedness may not be sufficient to predict potential responses to these factors.