Date of Award
Master of Science
Exotic plant species can be a serious threat to native ecosystems and the human economy. They have often been found to grow in greater abundance along roadsides, and seem to use them as corridors of invasion into the surrounding habitats. This study sought to determine whether there were any relationships between the distribution of exotic plant species and adjacency to roads in southern Illinois. To test this question, I conducted two research projects. For the first project, I ran transects from active and abandoned roadsides into adjacent forest interiors to collect data on the presence and abundance of exotic species. Along most roads, exotic species richness declined with increasing distance from the road. In most cases, abandoned roads were more likely than active roads to have a high abundance of Lonicera japonica and Rosa multiflora. For the second project, I collected geographical data for exotic species from field studies, herbaria records, and literature records, and compared them based on distance from the nearest road, family composition, and life form composition by both number of species and number of records. On average, herbaria records were farther from the road than field studies. Composition of families and variety of life forms were not significantly different when comparing by number of species, but were significantly different when comparing by number of records.
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