Invasive Plant Management

The Exotic Plant Management Team treating dandelions in Kenai Fjords National Park.

NPS

Effective management of invasive plant species takes an integrated approach incorporating inventory and prevention, treatment, and restoration.

Inventory

Preventing the establishment of invasive species is always the best choice. Inventories, or field surveys, are used to assess the condition of our park lands and look for any new establishment of invasive plants. For a state the size of Alaska, field surveys for invasive plants are critical for detecting infestations before they get out of control. Rather than randomly surveying for invasive plants, areas are prioritized according to the amount of human access and use that has occurred there in the past. Global positioning system (GPS) units enable the Alaska Exotic Plant Management Team (EPMT) to mark an infestation once found, so that its location is recorded for the future.

Treatment

Controlling invasive plants poses a special dilemma because once an infestation is identified it is often already so large that containment is not only difficult, but also expensive. In Alaska parklands, a special emphasis is placed on early detection of infestations and prevention of new infestations. The Alaska EPMT generally takes an integrated approach, using a combination of the following three methods to contain weed infestations and eradicate them where possible.1

Manual

Hand-pulling and root removal works for small infestations of most species, but it's difficult, time intensive, expensive, and requires repeated efforts.

Mechanical

Cutting is effective for some species, like Melilotusalba (white sweetclover), but not others, like Cirsium arvense(Canada thistle).

Chemical

Herbicides are generally most effective in controlling weeds and stopping their spread, but they can be expensive and may have environmental impacts if used improperly.

Restoration

Before beginning any weed control effort, it is important to consider what plant species are likely to colonize an area after management actions and if it is necessary to revegetate the area with native plants or if it is possible to allow the area to be restored through natural processes. Generally, the plant species most likely to successfully establish and resist weeds at a disturbed site are those native species commonly found in disturbed areas. Native species that have been successfully used for revegetation in Alaska's parklands include Hedysarum alpinum (eskimo potato), Oxytropis campestris (milk vetch), Elymus macrourus (tufted wheatgrass), and Poa alpine (arctic bluegrass).

Due to concerns about introducing non-local genetics into the parks, all seeds and plants used are locally sourced.