Global patterns of ectomycorrhizal introductions

Summary•  Plants have often been moved across the globe with intact root systems. These roots are likely to have housed symbiotic ectomycorrhizal (EM) fungi and the movement of plants may have facilitated the introduction of EM fungi. •  Here, we report data compiled from a newly created database of EM fungal introductions. We estimate the magnitude of EM fungal introductions around the world and examine patterns associated with these introductions. We also use the data to develop a framework for understanding the invasion biology of EM fungi. •  At least 200 species of basidiomycete and ascomycete EM fungi have been moved from native ranges to novel habitats. The majority of recorded introductions are associated with Pinus or Eucalyptus plantations in the southern hemisphere. Most introduced species appear to be constrained from spreading in novel habitats and associate only with their introduced hosts. Aspects of life history, including host range, may influence the ability of EM species to establish or invade. •  Human‐caused introductions of EM fungi are a common and global phenomenon. The mechanisms controlling EM fungi in novel habitats and potential impacts of EM fungal introductions are almost entirely unknown.