Lewis and Clark National Historical Park
State and national parks in Clatsop County approach invasive plants with different levels of intensity, but none of them can afford to ignore the invaders.
Such management could become a more active part of work done at the Nehalem Bay Management Unit, a complex of state parks in Clatsop and Tillamook counties that includes popular parks like Ecola and Nehalem Bay. The unit is finishing up an integrated pest management plan, a tool to more efficiently deal with pests — both animal and plant — in the parks.
Similar plans have existed for awhile at other state parks but they were never implemented consistently across Oregon.
“I think the thing we’ve gotten better at is education, letting people know that what they do in their landscapes at home or as they bring things into the parks that come from another region — what potential that has for devastating consequences,” said Ben Cox, park manager of the Nehalem Bay unit.
The Nehalem Bay unit parks have actively procured firewood for campers from regional sources and included education about invasive plants in interpretive offerings like ranger and campfire talks.
What has been missing is more of the active management like the follow-up work that needs to happen after crews have dealt with invaders.
“That’s the thing we’ve missed as a department and we’re getting back to that,” Cox said.
‘A weed is not a weed’
“Like many issues, the more you know about invasive species, the more complicated it becomes,” said Carla Cole, natural resources project manager at Lewis and Clark National Historical Park.
“A weed is not a weed is not a weed is not a weed,” she said. “No species is inherently ‘bad.’ It all depends on where it is, and how it is interacting with the ecosystem it has ended up in.”
At Lewis and Clark, the biggest threats include the usual suspects: holly, blackberry species and English ivy. English laurel is on the rise.
Plant management entwines with restoration work in the park — it’s hard to separate one from the other — and so invasive plants are often a top priority.
Invasive species impact every acre of the 3,400 acres at Lewis and Clark, though not necessarily by their physical presence, said Chris Clatterbuck, the park’s chief of resource management.
Pacific Northwest forests are productive environments, capable of growing and sustaining diverse plant populations. With invasive plants already present in portions of the park and in the private lands around the park, the threat of invasion is real.
“Because what might be perfectly great habitat, all native species, a bird could drop a holly berry and you’ll find a holly tree after a while,” Clatterbuck said.
The park collaborates with school groups and organizations like the Clatsop Soil and Water Conservation District or the North Coast Land Conservancy to manage invaders like Scotch broom or yellow iris and purple loosestrife in the Youngs Bay watershed. Through these partnerships, park staff can curb the spread of invasive species into the park.
“This is much more cost-effective than waiting until the infestations get out of control and into our parklands and eradication costs skyrocket,” Cole said.
The Nehalem Bay unit is in the middle of a project to clear 20 acres of trees and invasive brush north of the Nehalem Bay State Park airstrip. The project will close down an entrance to the park on weekdays throughout most of March.
The trees need to be cleared for the airstrip to be usable, but the park plans to take advantage of the situation to remove rampant Scotch broom, replace it with native kinnikinnick and control the invaders’ progress by introducing desired competitors for that prime real estate.
At Lewis and Clark, invasive plant management can also be about protecting historic characteristics of the sites — the landscapes native people navigated, the plants they used for medicine, food, clothing and basketry, the world that the explorers who give the park its name encountered.
“It’s important to be able to maintain those cultural landscapes,” Clatterbuck said.
This kind of management can be years in the making. At this point, park staff feel they have a handle on older, mature invasive plants, but some species have become naturalized over the years. In some cases, it would take an inordinate amount of control to convert the landscape back. There is no aggressive anti-dandelion policy, for example.
Rangers focus on new infestations and on species that are particularly aggressive, species that will crowd out other species and create a monoculture.
The battle against invasive plants is a constant and seemingly never-ending process. Victories may feel scattered, rare and temporary, but park staff can point to several positive changes over the years.
The park at one point acquired around 900 acres of forest that hadn’t been treated for common invasive plants like holly and ivy. Over the years, crews eliminated much of the seed-producing holly. Where the park has done tidal restoration, it has been possible to drown out invasive plants.
“You see what was once a mixture of pasture grasses is now a full wetland community with a whole suite of native wetland species,” Clatterbuck said.