Global climate changes will lead to regionally divergent trajectories for ectomycorrhizal communities in North American Pinaceae forests

Ectomycorrhizal fungi (ECMF) are partners in a globally distributed tree symbiosis that enhanced ecosystem carbon (C)-sequestration and storage. However, resilience of ECMF to future climates is uncertain. We sampled ECMF across a broad climatic gradient in North America, modeled climatic drivers of diversity and community composition, and then forecast ECMF response to climate changes over the next 50 years. We predict ECMF richness will decline over nearly half of North American Pinaceae forests, with median species losses as high as 21%. Mitigation of greenhouse gas emissions can reduce these declines, but not prevent them. Warming of forests along the boreal-temperate ecotone results in projected ECMF species loss and declines in the relative abundance of C demanding, long-distance foraging ECMF species, but warming of eastern temperate forests has the opposite effect. Sites with more ECMF species had higher activities of nitrogen-mineralizing enzymes, suggesting that ECMF species-losses will compromise their associated ecosystem functions.