Designing Weed Treatment Projects

Designing Weed Treatment Projects

Table . Treatment project objectives by weed classification

Treatment projects should be based on an established inventory including necessary mapping of infestations. Program or project plans should emphasize areas where weed management actions can be focused to (1) eradicate (locally), (2) contain, or (3) control high risk invasive species. Treatment efforts may be focused on dispersed areas or areas of concentrated use. Dispersed areas include, but are not limited to transportation and utility ROWs, fuels treatment areas, sensitive habitat for rare species, water bodies and wetlands, irrigation ditches, grazing allotments, wildlife winter range, fire-breaks in burned areas, timber sale areas, wilderness areas, research natural areas, etc. Examples of areas of concentrated use include developed recreation sites, boating areas, facilities, corrals, stock ponds, and fire camps. High use recreation areas (trails, campgrounds, etc.) and commonly used livestock trails in particular should have high priority for weed control. For prescribed burns, the project area should be inventoried and evaluated for potential weed spread with regard to the fire prescription. Areas with moderate to high weed cover should be managed for at least two years prior to the prescribed burn to reduce the number of weed seeds in the soil. Vigilant weed management will be necessary after the burn.

To prevent expansion of weed populations, infestation perimeters and satellite populations should generally be treated first since weeds often spread as an advancing front (Enloe, 2006). Treatment of satellite populations of relatively large infestations should be emphasized over infestation perimeters because of potentially higher rates of spread associated with satellite populations (Moody and Mack, 1988). A combination of containment and strategically located eradication treatments may be used to stop large infestations from spreading (Zamora et al., 1989). EDRR for new infestations will be a necessary component of any containment-eradication plan using adaptive management. When large-scale weed control over a landscape does become necessary, relatively large areas may be divided up into smaller units and worked from the outer edges toward the interior of the infestation (Enloe, 2006). For invasive plant species found in riparian areas, treatment projects should be implemented first at the top of the watershed and then moved down the watershed in successive treatments.

It should be anticipated that many weed populations will recover to pre-treatment densities over the long term unless the underlying causes of weed invasion are corrected (Jacobs, 2007). Underlying causes for the original invasive plant infestations (overgrazing, off-road driving, fire regime change, etc.) should be addressed in project planning. In some cases, early seral invasive species can dominate a treated area but can be expected to disappear over time due to natural succession (Jacobs, 2007). Treatment projects should always consider necessary measures for rehabilitation and restoration as part of an overall plan. When possible, perennial native grasses that have been suppressed by weed infestations should be encouraged to regain dominance and forestall return of weeds. In some cases, revegetation with native species may be necessary.