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2002 Exotic Plant Management - Chemical Control

Devils Tower NM
Ann Hebig
Devils Tower National Monument (DETO) was designated by President Theodore Roosevelt in 1906 as the nation's first national monument. It is part of the Black Hills Region in northeastern Wyoming and encompasses 1,347 acres. There are 56 exotic plant species within the Monument (Tessler 1991). Of these, 12 have been designated as noxious weeds by the state of Wyoming (WY Dept. of Ag. 1973). The Monument's Interim Exotic Plant Management Plan (1991a) lists 22 exotic plants as widespread disruptive, six as localized disruptive, and 27 as innocuous. The current extent of exotic plant coverage in the Monument is probably having community level or ecosystem level effects thereby significantly altering natural processes such as fire regimes, nutrient cycling, hydrology, successional patterns, or altering species composition and reducing populations of native plants and animals. Monument staff uses mechanical, chemical, and biological control methods in controlling exotic plants. Beginning in FY2002, the Northern Great Plains Exotic Plant Management Team (NGP EPMT) began assisting the park with exotics control. Annually, the park is schedule to be served approximately 10-15 days by the team. Last year the EPMT provided us with over a million flea beetles for leafy spurge, surveyed almost 200 acres, and treated 79 acres of leafy spurge with herbicide.

The Exotic Plant Management Plan states there are three goals to controlling exotic plants: (1) protect natural animal and plant communities and processes within the monument, (2) keep Wyoming designated noxious, exotic plants from spreading to land surrounding the monument, and (3) maintain aesthetic views for visitors of the monument. Objectives to accomplish these goals include: manage areas for release of biological control insects; control Wyoming designated noxious exotic plants near developed areas, roads, and trails; confine widespread disruptive, exotic plant species; control localized-disruptive exotic plant species; and remove aesthetically intrusive exotic plant species near developed areas, roads, and trails.

In 2002, five staff members were dedicated to the control of exotic plants within the Monument. One staff member was a Natural Resource Management Specialist in the National Park Service Intake Trainee program. Another staff member was a Student Conservation Association Resource Assistant funded by the Devils Tower Natural History Association. Three additional employees were biological science technicians hired specifically for the exotic plant management program. Herbicide spray methods included the use of backpacks, all-terrain vehichles (ATVs), and high-capacity truck mounted sprayers. These methods are illustrated in the included digital photos. A total of 238 acres of exotic plants were treated with herbicides by park staff and the EPMT throughout the park. This included 18 acres of common mullein, 54 acres of hound's tongue, 29 acres of Canada thistle, and 137 acres of leafy spurge (58 by DETO staff and 79 by the EPMT).

Field data was collected by all staff using a Trimble GeoExplorer 3 GPS unit with a data dictionary. Data was differentially corrected, edited and exported to ArcView shapefile format using Pathfinder Office v 2.7 software. All exotic plant data was originally collected in NAD27 UTM zone 13 north, but was later converted to NAD83. The map shows the distribution of exotic plants treated during the 2002 field season.
April 08, 2004