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).