Invasive plant surveys reveal problem in plants throughout Southeast

Posted: Wednesday, November 12, 2008

It has become evident that invasive species are capable of truly altering our Alaska ecosystems. Invasive species cost the world economy of $1.4 trillion in 2006 and we must acknowledge that there is no invisible bubble deflecting invasive species from entering the state of Alaska. New species are reported in Alaska each year and the plants that are already here are spreading and colonizing more area each and every year. It is impossible to say when these plants are going to start seriously impacting Alaska's economy but it is understood that this will happen if Alaskan's don't prevent the spread in their state.

Courtesy Of Melinda Lamb
Courtesy Of Melinda Lamb

To better understand what needs to be done in Alaska, surveys for invasive plants were conducted along the majority of the road systems in Southeast Alaska. Knowing what invasive plants are in Alaska and where they are can help to prioritize the management of the most aggressive plants. We also use this information to alert the public to species of concern and work on prevention of spread.

Intensive surveys funded by the Forest Service State & Private Forestry and the National Forest System were conducted from 2005-2007. These surveys used a systematic protocol that inventoried all non-native species at ¼ mile intervals along major roads in southeast Alaska. The surveys took place around Prince of Wales Island, Ketchikan, Wrangell, Petersburg, Kake, Juneau, Sitka, Haines and Hoonah. More than 2,000 miles of roads were surveyed in Southeast Alaska.

The most invasive plant reported from the surveys was Spotted knapweed. This species costs the state of Montana over $14 million a year and is found covering more than five million acres. It has been found in seven locations around Southeast Alaska from Ketchikan to Haines. This species has not yet been found in Juneau but should be watched for ardently.

Orange and yellow hawkweeds are found throughout southeast Alaska. Orange hawkweed is much more wide spread throughout the region and has thoroughly infested Haines, Juneau, Ketchikan, Petersburg, Prince of Wales, Sitka and Wrangell. This plant is not yet found in Hoonah.

Canada thistle and bull thistle are also problematic plants in Southeast Alaska. Canada thistle is more difficult to control and has completely taken over the city street shoulders in the town of Haines. While you can also find bull thistle in Haines, the population has not exploded like the Canada thistle. Canada thistle is also found in Sitka, Petersburg, Prince of Wales, Ketchikan and Wrangell. Bull thistle can be found in Gustavus, Prince of Wales, Ketchikand and Wrangell as well.

If you want to find some invaders in Juneau, you can look for common tansy, ox-eye daisy, perennial sowthistle, white sweetclover, garlic mustard, reed canarygrass, sweetrocket, ornamental jewelweed, herb-Robert and bohemian knotweed. Also look out for opportunities to join in community weed pulls where you can learn to identify invasive plants and learn more about techniques for controlling them. For more information on future weed events or for more maps and complete summaries of the invasive plant surveys contact

• Melinda Lamb works for Forest Health Protection in the U.S. Department of Agriculture, Forest Service Alaska Region.

Not in My Backyard is a monthly feature about invasive species created by U.S. Forest Service botanist Ellen Anderson. She can be reached at

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