SEATTLE — The holly and the ivy, the yuletide carol goes, invoke “sweet singing of the choir.” Not around here they don’t, where environmentalists and tens of thousands of volunteers mutter far harsher words as they battle to rid Northwest woodlands of the nonnative invaders.
The wet, mild climate of Western Washington and Oregon is ideal for English ivy and English holly — ornamental plants beloved when they stick to the yard or show up in Christmas wreaths and other decorations. But they are hated when they beset parks, green spaces and forests.
Ivy “smothers everything, like a blanket,” says Tor Bell, restoration manager for the Seattle environmental group Mountains to Sound Greenway.
Environmentalists say runaway holly competes with native trees, while ivy rapidly forms thick mats on forest floors and urban lots that kill all other plants. It streaks up trunks to engulf trees with a half-ton or more of vines and leaves, causing them to topple in winter storms.
For years, volunteers, ranging from Washington’s lands commissioner to Portland’s No Ivy League, have devoted themselves to the backbreaking drudgery of digging out the persistent plants.
Bell’s group is working on a project to restore the four-acre Riverfront Park in North Bend, east of Seattle, where ivy has swamped 95 percent of the trees. Ella Elman of EarthCorps says her group surveyed Seattle’s 8,000 acres of public land 10 years ago and found that if just the ground ivy were clumped together it would cover more than a square mile.
“We’re basically going to be losing our native forest if we don’t do something about it,” Elman says.
Arthur Larson knows the problem first hand. As a volunteer with the Nature Consortium, the retired carpenter joins crews that go out three times a week to fight ivy, holly and other invasive plants in the West Duwamish greenbelt, a 500-acre forest in southwest Seattle.
On a recent outing, he and five others sawed ivy vines up to 4 inches thick, killing the ones that were climbers snaking to the tops of 100-foot trees.
“It’s a good aerobic workout,” Larson says. “You just take it one tree at a time. It’s just slow, tedious work.”
Lands Commissioner Peter Goldmark will second that. He spent a September day manning a shovel with Mountains to Sound Greenway volunteers, digging out holly on Tiger Mountain, a forest preserve east of Seattle. “It was really hard work because some of these holly trees are 10 to 15 feet tall, so they’re a significant adversary,” he said.
Nearly every community in western Oregon and Washington has at least one and sometimes dozens of groups combating ivy and other invasive plants.
No one knows how many take part, but Dawn Blanch of Seattle Parks and Recreation says over 18,000 volunteers last year pulled ivy and did other restoration just in Seattle’s park land. Mountains to Sound Greenway says it had at least 4,000 such volunteers, while Mark Tomkiewicz of the Nature Consortium says 5,000 a year work in the Duwamish greenbelt.
Portland’s 8-square-mile Forest Park is at least two-thirds infested with ivy, says Kevin McWhirter, volunteer coordinator for the park department’s No Ivy League. He says Portland alone has at least 15 organizations fighting invasive plants.
English holly is common in yards and is a cash crop at small nurseries in Washington and Oregon, while English ivy was long favored as a fast-growing ground cover for landscaping.
Both are evergreens, giving them an advantage over trees that lose leaves in the winter. Both are shade-tolerant and have few natural predators — scientists note many animals won’t eat the prickly holly and almost none like waxy ivy leaves.
However, both plants produce berries, which birds eat and spread. While some herbicides work on holly, the only really effective ivy control is to rip it out.
Few believe people will give up holly for decoration or landscaping. Another variety, American holly, is native to the East Coast and prized there for its beautiful leaves and berries. English holly, originally from Eurasia, is popular on the West Coast.
McWhirter and others say it’s impossible to eradicate ivy, but it can be controlled. Tomkiewicz says that once it’s removed, native species should be immediately planted so ivy or other weeds don’t sneak in.
Homeowners, he and others say, should aggressively prune ivy so it stays in small ground patches and never forms flowers or berries.
Better yet, they say, just don’t plant it.
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