Climate change and plant invasions are altering many environments worldwide, with potential consequences for soil microbial composition. To predict future trajectories of microbial communities, we must identify the dominant environmental controls over their structure. In the current study we constructed a phylogenetic tree with all published 18S and 28S rDNA soil fungal sequences in GenBank to determine how phylogeny, plant community type, soil type, precipitation, and temperature influence the global distributions of fungal functional groups. We hypothesized that (1) arbuscular mycorrhizal fungi (AMF), ectomycorrhizal fungi (ECM), and plant pathogens, which are dependent on host plants, should be correlated with plant community composition; (2) saprotrophic or decomposer fungi should be correlated with precipitation and temperature owing to biological and physical constraints imposed by the decomposition process; and (3) fungi from different phyla, specifically Ascomycota, Basidiomycota and Glomeromycota, should differ in their response to environmental parameters due to physiological differences between taxa.  
Results/Conclusions

Arbuscular mycorrhizal fungi were significantly correlated with soil temperature and plant community composition. The community composition of ECM fungi was controlled by soil moisture regardless of phylogeny. Pathogenic fungi within the Ascomycota were associated with plant community composition, while pathogens within the Basidiomycota were unrelated to any factors. The community composition of saprotrophic fungi within the Ascomycota was correlated with soil temperature while saprotrophic fungi within the Basidiomycota were correlated with soil moisture. Overall, some plant-associated fungi were highly correlated with plant community composition. In contrast, fungi that are saprotrophic or potentially mixotrophic (ECM) were associated with environmental parameters. Since temperature, precipitation, and vegetation structure are altered by global change, fungal distributions are likely to be affected as well.