Holly, ivy not welcome in Northwest woodlands

The holly and the ivy, the yuletide carol goes, invoke "sweet singing of the choir."

Not around here, 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.

But they are hated when they beset parks, green spaces and forests.

Ivy "smothers everything, like a blanket," says Tor Bell, restoration manager for Mountains to Sound Greenway.

Environmentalists say runaway holly competes with native trees, while ivy 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 plants.

Bell's group is working on a project to restore Riverfront Park in North Bend, 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.

Nearly every community in Western Oregon and Washington has at least one and sometimes dozens of groups combating ivy and other invasive plants.

Dawn Blanch of Seattle Parks and Recreation says over 18,000 volunteers last year pulled ivy and did other restoration in Seattle's parks.

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.

Tomkiewicz says that once invaders are removed, native species should be immediately planted so ivy or other weeds don't sneak in.

Homeowners, he and others say, should sharply prune ivy so it stays in small ground patches and never forms flowers or berries.

Better yet, they say, just don't plant it.