Invasive Plants

Yellow Toadflax is a highly invasive ornamental plant.

P. Miller

What is "invasive"?
Organisms which don't occur naturally in a particular area but have been introduced (intentionally or otherwise) by human activity are known as "exotic species," "non-native species," or "alien species." These terms are interchangeable. "Invasive" refers specifically to non-natives which cause significant harm to the ecosystem or to human health or wellbeing. Only a small portion of non-native species are well-suited enough to a particular environment to become invasive there. A tomato planted in an Alaskan garden is certainly an exotic species, but it's very unlikely that it could ever become invasive. Some garden plants, however, such as Yellow Toadflax (Linaria vulgaris, also called butter and eggs or wild snapdragon), are highly invasive and can wreak havoc on Alaskan ecosystems.

How do invasive plants cause problems?
The native species in any given ecosystem have coexisted and evolved alongside one another for thousands or millions or years. Each has its own distinct niche in the ecosystem. Invasive plants disrupt this balance in a number of ways. Some simply outcompete natives by growing larger and shading them out. Many invasive plants rapidly colonize disturbed areas, upsetting the natural process of succession. Others release chemicals which damage other plants or inhibit their ability to reproduce. Invasive plants can change how an ecosystem functions, reduce biodiversity, and even cause the extinction of native species. In some cases, they can also be economically damaging or detrimental to human health.

Invasive Plants in Kenai Fjords National Park
Alaska's geographic isolation and cold climate have helped to slow the spread of invasive species. Compared to other regions where many invasive plants have become too widespread to control, most of Alaska's infestations are in an early stage during which eradication or containment are still possible. In Kenai Fjords National Park, invasive plants are mostly restricted to disturbed and high-traffic areas along the road to Exit Glacier, near the parking areas and along trails. Some backcountry infestations have been found, but most of the park remains invasive plant-free. Keeping it that way will require ongoing effort in terms of visitor education, community involvement, and rigorous monitoring and management of existing infestations.

Some of the invasive plants found in or near the park include common dandelion (Taraxium officinale), annual bluegrass (Poa annus), pinapple weed (Matricarea discoidea), common plantain (Plantago major), common timothy (Phleum pratense), and white sweetclover (Melilotus alba).

 

This boot brush at the Exit Glacier Nature Center helps prevent the spread of invasive plants.

NPS Photo

What You Can Do
Seeds from invasive plants can hide on shoes, clothing, backpacks, and vehicles. Before hiking in the park or other natural areas, inspect your clothing and gear to make sure you're not carrying any stowaways - especially if you've been hiking in another region or country where you might have picked up seeds. There is a special boot brush in front of the nature center at Exit Glacier. Before you go out on the trails, take a moment to brush off your boots. It's also important to avoid planting potentially invasive plants in your own garden. For more information, see the University of Fairbanks Cooperative Extension Service's guide for gardeners, "Don't Plant a Problem".

 

-For more information about specific invasive plants in Alaska, visit the Alaska Exotic Plants Information Clearinghouse (AKEPIC) website.

-For information on local volunteer and community weed-control programs, see the Kenai Pensinsula Cooperative Weed Management Area website.

-For more about the National Park Service's efforts to control invasive species and how you can help, visit the Alaska Exotic Plant Management Team.