Brush the invaders off your boots

Refuge Notebook
Boot brushes are now installed at 25 trailheads and 5 boat launches, part of an integrated pest management approach to controlling the spread of exotic invasive plants into the interior of the Kenai National Wildlife Refuge.

You've probably heard a lot about invasive plants, maybe to the point that the message goes in one ear and out the other. A lot of exotic invasive plants have desirable attributes like showy flowers that look good in a garden -- think oxeye daisy, toadflax, common tansy -- which is often why they get introduced to the Kenai Peninsula in the first place. Other exotic invasives were introduced because they make good forage or stabilize road banks (reedcanary grass) or fix soil nitrogen for agriculture (sweetclover).


The problem is that by the time weed populations are big enough and dense enough to show their undesirable attributes like clogging our streams or displacing native vegetation, it's too late to do much about it. Decades of experience in the Lower 48 and elsewhere in the world tell us that the best way to protect natural areas is to not introduce them. If that fails, the next best thing is to eliminate them as soon as they're detected -- similar to the way we deal with cancers. This approach is called Early Detection and Rapid Response (EDRR).

Biological staff have been practicing EDRR at the Kenai National Wildlife Refuge for several years. We initially surveyed the human footprint on the refuge (trails, seismic lines, roads, pipelines, campgrounds) in 2005. In 2005 and 2006, we surveyed historic cabins on the far end of Tustumena Lake after the Glacier Creek Fire. Also In 2006, we sampled the Hansen Horse Trail and worked with scientists from Colorado State University to establish 74 permanent monitoring plots on disturbed areas of the refuge. In 2007 and 2009, we surveyed the facilities, 62 pads and adjoining roads in the Swanson oil and gas field. 

Along the way, we found 71 exotic plant species, many of which are both invasive and potentially injurious. And we didn't just document them. We eliminated orange hawkweed in the permitted wood cutting area, toadflax at the Visitor Contact Station on the Sterling Highway, bird vetch near Jim's Landing, oxeye daisy enroute to the lower Skilak boat launch, Scotch broom on Funny River Road, perennial sowthistle in the Swanson oil and gas field, and yellow hawksbeard in gravel around our hangar at the Soldotna Airport. We've been treating reedcanary grass, sweetclover, and yellow hawkweeds in the Swanson oil and gas field with herbicide for several years to try to eliminate them before they can spread down the Swanson River.

Even as we clean up the refuge, we've been trying to prevent more weeds from dispersing into the refuge interior. We do our best to keep the refuge's hangar, floatplane dock, and maintenance yard (where our vehicle fleet is kept) weed free with herbicides. Employing this same strategy of minimizing spread by targeting access points on the refuge, we apply herbicide and have deployed boot brushes at 25 public trailheads and five boat launches (see photo).

The idea is simply to prevent weeds from spreading into the refuge interior by stopping them at discrete points where they can be managed.

We certainly can't win this war against weeds alone. The 175-mile refuge boundary that runs from Point Possession in Turnagain Arm to the Fox River at the headwaters of Kachemak Bay is a rapidly expanding urban interface. Land practices associated with new cabins in the Caribou Hills and north of Captain Cook State Park may introduce exotic invasive plants into remote areas of the refuge that we can't treat effectively. The discovery of Elodea in rivers and lakes around Fairbanks and Anchorage, the first truly submerged freshwater invasive plant in Alaska, doesn't bode well for the Kenai where float planes and motor boats from other parts of the state are regular visitors.

So even as the Kenai Refuge has taken action, we've worked with our partners through the Kenai Peninsula Cooperative Weed Management Area ( to develop a strategic plan for managing reedcanary grass, identify species of management concern, host weed pulls, and spread the message through sponsoring an annual weed workshop, publishing brochures, and giving talks. We keep track of exotic plant distributions by helping to fund, and contributing our survey data to, the online Alaska Exotic Plants Information Clearinghouse ( 

And not only is the risk of introducing new exotic, invasive and injurious plants increasing with the addition of about 1,000 new residents to the Kenai Peninsula Borough every year, our warming climate increases the likelihood of these species getting established. Our new ecologist, Libby Bella, modeled invasive species spread in response to climate change as part of her doctoral dissertation at the University of California-Davis. You can see her spatial models that predict future distributions in Alaska at

At the end of the day, we need your help as well: stay informed, don't plant species that can spread outside the garden, hose off your ATV, and clean your boat props. Switch your pack horse over to certified weed-free forage while using refuge trails.

If you see a new infestation of an invasive plant or a plant you've never seen, please call the refuge, the Homer or Kenai Soil & Water Conservation Districts, or the University of Alaska Cooperative Extension. Times have changed -- despite Nancy Sinatra's 1966 ode to how your boots are made for walkin', please use the boot brush first.  

John Morton is the supervisory biologist at Kenai National Wildlife Refuge. You can find more information about the refuge at or