If you build it, they will come: Roads facilitate the spread and establishment of invasive plants

Background/Question/Methods

Roads and road networks are major contributors to the spread and success of invasive plants. Not only do roads increase the movement of people, vehicles and equipment into an area, roadsides are also a prime habitat for the establishment of invasive plants. The frequent disturbance and greater light availability can greatly enhance the success of non-native plants and other weedy species. The creation of new roads is associated with the invasion of new species, and the maintenance of existing roads also disperses invasives into new areas. Both paved and unpaved roads have been associated with higher prevalence of invasives and dispersal of new invasive plants. We report on a series of experiments looking at the association between roads and the prevalence of invasive plants, as well as the human-mediated dispersal and establishment of invasives through natural gas development in Pennsylvania. We also synthesize from other studies examining how to mitigate these problems through roadside management and vehicle cleaning programs.

Results/Conclusions

Invasive species are more prevalent closer to roads versus further away from roads. For example, Microstegium vimineum has the highest predicted occurrence 10 m from roads, with much smaller probability of occurrence 150 m from roads. Human activities such as road maintenance are spreading invasive seeds several orders of magnitude further than natural dispersal. Certain invasive plants have stronger associations with roads than others. Road creation and maintenance are necessary parts of our current society that we expect will continue, and these results highlight the need for careful consideration of the increase in plant invasion associated with roads.