Conclusion
Our results show a global pattern of anthropogenic disturbance influencing the distribution of plant cover associated with the different types of mycorrhizal fungi in mountains. AM and NM vegetation cover increased along mountain roads, while the cover of EcM and ErM vegetation decreased. This pattern was consistent across regions but varied in intensity along gradients of environmental factors and depending on the prevailing type of mycorrhiza in the natural vegetation. Indeed, cold-climate regions with higher representation of EcM and ErM vegetation showed greater increases in AM vegetation as a result of road disturbance. Non-native plants were almost exclusively associated with AM fungi or NM, and in turn more successful in environments strongly dominated by AM associations, suggesting that disturbance could be facilitating non-native plant invasion through changes in local mycorrhizal communities. While we hypothesize that this shifting effect of disturbance on the distribution of mycorrhizal types could be caused by changing abiotic factors and in particular by changes in nutrient availabilities, further research with a focus on testing individual drivers associated with disturbance in an experimental setting would be required to truly understand which underlying processes drive the shifts we observed. Regardless, our results represent an important first global study of the role of anthropogenic disturbances in shaping plant communities through the mycorrhizal fungi they associate with. These findings have important implications for vegetation restoration worldwide, as they suggest that roadside disturbance can change the fundamental make-up of EcM- and ErM-dominated plant communities, potentially shifting communities between alternative stable states of mycorrhizal dominance that could be very difficult to reverse (Averill et al. 2022; Fukami et al. 2017).