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Open-File Report 2011-1048

Predicting Spread of Invasive Exotic Plants into Dewatered Reservoirs After Dam Removal on the Elwha River, Olympic National Park, Washington

By Andrea Woodward and Christian Torgersen, U.S. Geological Survey, and Joshua Chenoweth, Katherine Beirne, and Steve Acker, National Park Service

Thumbnail of and link to report PDF (6.25 MB)Abstract

The National Park Service is planning to start the restoration of the Elwha River ecosystem in Olympic National Park by removing two high head dams beginning in 2011. The potential for dispersal of exotic plants into dewatered reservoirs following dam removal, which would inhibit restoration of native vegetation, is of great concern. We focused on predicting long-distance dispersal of invasive exotic plants rather than diffusive spread because local sources of invasive species have been surveyed. We included the long-distance dispersal vectors: wind, water, birds, beavers, ungulates, and users of roads and trails. Using information about the current distribution of invasive species from two surveys, various geographic information system techniques and models, and statistical methods, we identified high-priority areas for Park staff to treat prior to dam removal, and areas of the dewatered reservoirs at risk after dam removal.

First posted March 7, 2011

For additional information contact:
Director, Forest and Rangeland Ecosystem Science Center,
U.S. Geological Survey, 777 NW 9th Street
Corvallis, Oregon 97330

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Suggested citation:

Woodward, Andrea, Torgersen, Christian, Chenoweth, Joshua, Beirne, Katherine, and Acker, Steve, 2011, Predicting spread of invasive exotic plants into de-watered reservoirs following dam removal on the Elwha River, Olympic National Park, Washington: U.S. Geological Survey Open-File Report 2011-1048, 64 p.





Long-Distance Dispersal Mechanisms of Focal Species

Distribution of Invasives

Wind Vector

Water Vector

Mammal Vectors

Bird Vectors

Road- and Trail-Associated Vectors

Priority Areas



References Cited

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