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Medusahead invasion along unimproved roads, animal trails, and random transects

Davies, Kirk W, Nafus, Aleta M., Madsen, Matthew D.
Western North American naturalist 2013 v.73 no.1 pp. 54
Taeniatherum caput-medusae, animals, grasses, introduced plants, invasive species, landscapes, roads, trails, vehicles, Oregon
Medusahead (Taeniatherum caput-medusae [L.] Nevski), an exotic annual grass, is rapidly spreading and causing ecological damage across the western United States. Because this exotic plant occupies vast areas and because management resources are limited, it is critical that land managers prioritize where they direct treatment and monitoring efforts. Identifying where and by what means medusahead is spreading could provide valuable information to assist in determining where prevention and control efforts should be applied. We compared medusahead invasion levels along unimproved roads, animal trails, and random transects at 6 sites in southeastern Oregon to determine where medusahead was more common and to identify potential vectors for its spread. Medusahead was more common and its cover was greater along unimproved roads than along trails and random transects. Medusahead infestations were also larger along roads. Medusahead was more common along animal trails than along random transects, but differences were less evident. Our results suggest that medusahead spreads along roads. This outcome implies, though not conclusively, that vehicles may be one of the most important vectors for medusahead spread. Our results also suggest that animals may be a vector for medusahead dispersal; however, invasions were much more concentrated near roads than trails, suggesting that medusahead management along roads should receive higher priority. Medusahead invasion is not random across the landscape, and thus, control and monitoring efforts can be prioritized, based on potential vector pathways, to manage this invasive plant.