Revegetation Success and Weed Resilience of Wyoming Right-Of-Way Reclamation

RS02218Roadside revegetation within highway rights-of-way is a final step in road construction, and often occurs in areas that are difficult to reclaim due to harsh climate conditions and impacts of land disturbance, including topsoil removal, soil compaction, and the presence of noxious and invasive weeds. Wyoming Department of Transportation managers have focused on reseeding native plant species since the 1990s, and seed mixes are designed for application among six Level II ecoregions across the state. A study of 73 sites along 12 highways in central and southern Wyoming revealed that 36 percent of seeded species were present among sampled sites between two and twenty years after projects were completed. In addition, a minimum of one seeded species was detected along transects for all 31 roadside projects. Grasses were the most likely plant type to establish from seed mixes despite both the number of forbs in seed mixes, and the large number of native and non-native forbs present at field sites. While many seeded species were not detected along reclaimed roadsides, a higher abundance of seeded plants corresponded to a significantly lower number of introduced weeds. Moreover, a higher number of weeds along roadsides positively correlated with a higher number of weeds over the fence line, providing evidence that weeds may be spreading along road corridors and into nearby, undisturbed rangeland. Results of this study support seeding roadsides with native vegetation to minimize the number and abundance of undesirable, non-native species. Further study is needed to determine the factors that prevent establishment of seeded forbs along road rights-of-way in Wyoming