Differential responses of fungal guilds to climatic effects mediated by changes in dominant vegetation.

Climate is a major driver of fungal species distributions and community composition, yet disentangling the effects of climate-mediated changes in dominant vegetation from other climatic effects remains a key challenge. To separate climatic effects mediated by dominant vegetation from other climatic effects on soil fungal communities, we analyzed soil fungal communities from eight European altitudinal gradients including sites with homogeneous and heterogeneous dominant vegetation. We combined community-level analyses with species-level hierarchical modeling to assess how different fungal ecological guilds respond to climate. Our results reveal clear contrasts among fungal ecological guilds. Ectomycorrhizal fungi showed significantly higher community turnover along the climatic gradient than any other group and responded only weakly to changes in dominant vegetation, whereas plant pathogens, root endophytes, and saprotrophic fungi showed consistently stronger responses under heterogeneous vegetation. The realized climatic niche of ectomycorrhizal fungi therefore appears only weakly constrained by dominant vegetation, whereas the distributions of plant pathogens, root endophytes, and saprotrophic fungi are more strongly associated with climate-mediated vegetation change. Together, our findings demonstrate that fungal guilds differ markedly in the pathways through which climate shapes their distributions.