CANCELLED - Continental wind flow patterns structure soil fungal communities

Background/Question/Methods

Fungi are dominant members of soil food webs and regulate key biogeochemical cycles. Understanding the drivers of variation in soil fungal communities is critical to predicting their cumulative impact on decay rates, nutrient cycling, and plant growth. Wind represents the key dispersal vector for most mushroom forming fungal taxa, allowing spores to disperse long distances in wind parcels. Variation in wind direction and velocities is known to shape the biogeography and genetic structure of plant species, however the impact of wind on fungal community structure remains especially understudied. The dispersal of fungal spores is notoriously difficult to observe, and instead we study the outcome of fungal dispersal by testing several independent hypotheses relating wind direction and velocity with fungal community structure at the scale of the North American continent. Large-scale spatially explicit wind-flow data agglomerated and averaged 30-year window was integrated with landscape connectivity algorithms to probe the role of wind flow patterns in fungal biogeography. To study soil fungal communities, we leveraged two bioinformatically compatible continental-scale sampling networks including NEON sites spanning over 7000 soil cores, and employed molecular sequencing of the ITS1 region and clustering of sequences into operational taxonomic units (OTUs) at 97% similarity.

Results/Conclusions

We applied a generalized dissimilarity modeling (GDM) framework to assess the key environmental drivers of fungal community composition. Broadly, we identify the role of pH, mean annual temperature, and plant overstory as primary determinants of fungal community structure. Secondly, we tested the hypothesis that fungal community similarity is greatest when wind flow between sites is high. We calculated a directionless measure of wind connectivity for a given pair of sites by averaging the two directional wind flows and compared this measure to community similarity. After considering other environmental co-variates and geographic structure, we find support for the hypothesis that fungal communities connected by greater wind speeds are more compositionally similar across multiple scales of taxonomic organization. Notably, this correlation was strongest for mushroom forming fungal community members. Wind flow patterns are inherently asymmetric, with the possibility that between two sites, wind strength can be stronger in one direction than another. We tested the hypothesis that sites linked by more directionally asymmetrical wind flow patterns have more imbalanced community dissimilarity ratios. We find statistical support for this hypothesis, with variation across forest and grassland biomes. Together we identify a strong role for wind in influencing the distribution of soil fungal communities.