A slew of plants and insects make their way to the Northwest each year, entangling themselves in other plants and eventually eating away at the native flora. Some of them, like knapweed, are toxic to the touch.
Local, state and federal agencies across Southwest Washington and in the Gifford Pinchot National Forest are constantly working out the best ways to handle plants that are not just obnoxious but dangerous to a delicate ecosystem that will only get more vulnerable in a warming climate.
“The native plants here co-evolved and rely on each other in some way or another,” said Brad Krieckhaus, a botanist and invasive species specialist with the Gifford Pinchot National Forest. “When an invasive species comes in, it disrupts those relationships.”
Managing invasive species can be a difficult job that relies on constant surveyance and self-reporting, said Andrea Thorpe, a natural resources program manager with Washington State Parks.
“We have people who are trained to identify invasive species, and we have some of these sentinel efforts to try to find them,” Thorpe said. “And then in addition to that, there are different ways that the public can report invasive species that they see.”
Giant hogweed, a Class-A federal noxious weed and on the state’s invasive species list, was discovered last summer in the county. By state law, a noxious weed is “a plant that is highly destructive, competitive, or difficult to control by cultural or chemical practices.”
Property owners are paying for removal of these destructive plants, too, at $4.82 per parcel and 10 cents per acre. The program has seen success since 2020, officials say.
In April, the U.S. Forest Service joined an interagency agreement with Cowlitz County to add $40,000 to support the management of noxious weeds at the Mount St. Helens Volcanic Monument, according to a Daily News report.
In the Mount St. Helens region, traps are set by the U.S. Department of Agriculture in preparation for the spongy moth that comes north on an annual basis. Some traps can be seen near Lake Sacajawea in Longview. The traps employ artificial lights and sticky pheromone-coated glue to attract and ensnare the moth, according to sustainable magazine Plantura.
Native to Europe, the spongy moth can cause defoliation as it eats away at a wide variety of hardwood and softwood trees, according to Canada’s Invasive Species Centre.
People can also report when they see what looks like an invasive species to the Washington Invasive Species Council, Thorpe said.
Other species that overtake some of the flora and wildlife include the emerald ash borer and knapweed, Thorpe said. The department sends out arbor teams to find these species and work to manage them once they are spotted.
In Cowlitz County, the list includes insects such as scotch broom, dalmatian toadflax, Bruchidus villosus, Exapion fuscirostre, Mecinus janthiniformis and larinus, according to the county’s website.
“Another example that’s really pertinent to (Southwest Washington) is the emerald ash borer, which is a beetle that attacks our native ash trees as well as some other species of trees that was recently found down in the Portland area,” Thorpe said. “And while it hasn’t been found in Washington yet, if it were to come to Washington, it could devastate a lot of our natural species.”
Hawkweed species have also been “highly invasive” in the region, said Jennifer Mendoza, program coordinator with the Cowlitz County Noxious Weed Control Program, in an email to The Daily News.
Species can get established from disturbances in the ground, soil or waterways that can bring buried seeds to the surface, Mendoza said.
The 1980 Mount St. Helens is an example of an event that “provided significant disturbance,” she added.
High foot traffic also increases the potential for invasive species, as visitors to parks can unwittingly carry plants in or out on the bottom of their shoes or clothes, Mendoza said.
And sometimes invasive plants were brought in on purpose. Scotch broom was originally planted to stabilize embankments and has since become “quite a problem,” Krieckhaus said, because of how easily the seeds spread. The same is true for knapweed, he added.
Surveys have to be done constantly to help officials target and identify infestations, Mendoza said.
Knapweed especially causes a headache for researchers who have been trying to manage the plant for a decade now, Krieckhaus said.
“We’re trying to protect habitats. ... It’s a tough plant to get rid of,” Krieckhaus said.
Researchers generally know what to expect each season, Thorpe said. But a warming climate, which has made heat waves and droughts more common, has made that job harder in recent years.
“With a changing climate, it’s hard to say which native or invasive species may dwindle or thrive,” Mendoza said in an email, “though invasive species seem to hold an advantage in adapting to a changing climate.”
Spongy moths have begun to invade western Canadian forests, according to the Canadian Forest Service, creating a new problem for forests that typically didn’t have to deal with the insects.
“That’s also making it easier for some of these species to move around,” Thorpe said. “Some of the insects that maybe couldn’t have lived here before, because it got colder in winter, potentially (will be) able to get established here. It’s going to become a bigger and bigger issue moving forward. And so hopefully we can find some additional resources to deal with that as conditions change.”
