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S national Park Service U. S. Department of the Interior Sequoia and Kings Canyon National Parks Management Directive No. 038 Preventing Introduction and Spread of Invasive Non-Native Plants August 18, 2004 contents

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The intense soil disturbance inherent in construction, coupled with the import of equipment and materials that may harbor non-native plant seeds, make construction sites high-risk areas for invasion of non-native plants. Invasive non-native plants spread rapidly and aggressively from disturbed construction sites into adjacent natural communities. Once non-native plants become established, they can be very difficult and costly to eliminate. For example, until recently, Yosemite National Park was free of the highly invasive yellow star thistle (Centaurea solstitialis) until it was imported in contaminated soil on a Federal Lands Highway Project. It subsequently spread rapidly onto surrounding steep slopes, where control is extremely difficult and expensive.

Restoration sites, areas that have sustained high-intensity fire, fire line, and fuel breaks are also vulnerable to import and spread of non-native plants. Soils are disturbed to restore natural topography or to build fire line. Mechanized equipment, which can harbor non-native plant seeds, is often brought into the park. Materials that are imported to help mitigate soil erosion, such as straw and blanket, can contain non-native plant seeds.
The following principles will be followed in construction, restoration, and fire activities:

  1. Before any equipment is brought into the park, it will be pressure or steam washed in order to remove seed-containing soil. Examples of equipment are backhoes, tractors, loaders, excavators, dozers, bobcats, wheeled compressors, or trucks and trailers that have traveled off-road. This restriction shall not apply to equipment responding to initial attack of wildland fire where fire spread is threatening life or property.

  1. Staff is encouraged to wash equipment that has been off-road before moving it from place to place within the park, particularly when moving from lower to higher elevations.

  1. Topsoil shall not be imported into the park.

  1. Construction and restoration materials will be free of invasive weed seeds or other propagative plant parts. Such materials include boulders, soil, sand, gravel, rock, road base, straw, and silt and erosion control materials. Weed-free status may be ensured by pressure washing, steam washing, fumigation, heat sterilization, or certification from the supplier. Eliminating invasive plant seeds may raise the cost of some projects, but will prevent much more costly and prolonged invasive plant control efforts in the future.

  1. Large quantities of construction and restoration materials may be prohibitively expensive to sterilize. The risk of importing invasive plants in bulk materials will be minimized by inspecting proposed quarries or source sites for presence of invasive plants. If no local weed-free sources can be located, potentially contaminated materials may be accepted if mitigation is implemented. Mitigation might include stripping the top 12 inches of material or requiring fresh material stored less than one month, as specified by Vegetation Management staff.

For example, Yellowstone National Park uses a ranking system that considers the potential threat posed by the non-native species present in the quarry, the number of non-native plants present, the location of the plants (near crushing-loading sites vs. on the periphery), and whether the quarry has a weed management plan.

For construction projects, the project manager and/or COR will be responsible for contacting Vegetation Management staff to inspect sources. For materials procured by the park for use by park staff, the park Contracting Officer will be responsible for contacting Vegetation Management staff to inspect sources.

  1. Minimize the area of soil disturbance. Use hand line rather than dozer line where possible. Consider realigning trails or reducing the trail width to minimize disturbance. When removing invasive plants, consider using herbicides rather than digging out roots. Scrape road shoulders only where steep, material-shedding slopes make this action necessary.

  1. Consider the location of soil disturbance. On fires, resource advisors and incident staff should consult park Vegetation Management staff when locating hand line and dozer line in areas known to have populations of invasive species. Dozer line and hand line should be located well away from invasive species whenever possible. To avoid patches of invasive species when aligning new trails, planners should consult Vegetation Management staff.

  1. Minimize the frequency of soil disturbance. For example, disturbing an area once every five years creates less risk than disturbing it every year. If a site has to be cleared of vegetation yearly, consider paving it.

  1. After completing construction, or when rehabilitating fire line, revegetate the area or cover bare soil with local litter and duff mulch as soon as possible. This mulch will provide a source of seeds to reestablish native vegetation and reduce the risk of non-native seeds germinating. Ideally, the litter and duff should be collected from surrounding areas, but do not denude the collection area. Leave at least 50 percent of the material in place and don’t disturb vegetation.

  1. On fires, Vegetation Management specialists should be assigned as resource advisors to the incident management team whenever the spread of invasive species is probable. Vegetation Management specialists should be consulted in the development of fire line and burned area rehabilitation plans.

  1. If funding or staff is available, survey and remove invasive plants from future burn units and construction sites at least one year before a planned ignition or the start of construction. One year’s pre-construction survey should be funded by construction projects whenever possible. Contact Vegetation Management staff to conduct surveys.

  1. After fire or construction, and until sites are fully revegetated, schedule annual surveys by qualified botanical technicians for early detection of invasive plants to prevent them from becoming problems. One year’s follow-up survey should be funded by construction projects whenever possible.

  1. Consider the risk of non-native plant invasion when locating perpetually disturbed facilities, such as campgrounds and corrals. For example, campsites adjacent to meadows create a high risk for non-native plants to become established at the campsite and enter the meadow. Consider closure of such high-risk campsites.

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