May 25, 2005
Wednesday

Anchorage, Alaska - It's a tree that grows fast. In spring, it blooms with fragrant white flowers. Birds feast on its red berries. Moose won't chew it up. And the long dark cold of winter doesn't faze it.

That's why the European bird cherry, what your neighbors call the "May Day tree," became one of Anchorage's landscape darlings, a sturdy ornamental that now shades parks and lawns all over town.

But this arboreal romance has soured for some, just like the tiny bitter cherries that fall from its stems.

To the dismay of botanists and forest ecologists, the city's beloved May Day Tree has been slowly, inexorably, invading greenbelts and parks, choking out native trees.

In some spots along Chester Creek greenbelt, the entire forest floor is now carpeted by May Day seedlings - not little birches or young willows, not spruce or alder or cottonwood, said Michael Shephard, a federal forest health ecologist with the U.S. Forest Service, who grew up in Anchorage.

"If anything's going to be in the canopy (in the future), it has to start out as a seedling," he said. "So for a woody species, a tree or shrub, this one seems for Anchorage to be the most invasive plant that we have right now."

In Valley of the Moon Park, surrounded by stately May Day trees, May Day sprouts and saplings shroud the forest floor and line the stream bank. Other parks around town face similar growth.

And so this European transplant to North America, Prunus padus, is listed as a species to be monitored in the 2004 annual invasive plant bulletin by the U.S. Forest Service and the University of Alaska Fairbanks Cooperative Extension Service. The Alaska chapter of the American Society of Landscape Architects has informed its members that the tree is no longer recommended.

An evaluation by seven ecologists and plant specialists rated the tree as a relatively high weed risk to Anchorage, said Russian-born botanist Irina Lapina, with the Alaska Natural Heritage Program at the University of Alaska, Anchorage. She fondly recalled the species from the Ural Mountain forests, near where she grew up. Not here.

"This plant is native of (European) boreal forest, and it doesn't create such a dense stand and doesn't out-compete other trees and shrubs because they are all in the same level of growth," she said. "But here (in Anchorage), it is probably more competitive. . . . It's interesting to see my old friend misbehave like this."

As a result, landscape architects, botanists and others dealing with invasive plants in Alaska say residents should not plant any more May Day trees in town - especially next to greenbelts or forests.

"I love this tree," said Peter Briggs, a landscape architect at Land Design North. "It's one of the best trees up here for beauty, flowers in the spring, great smelling. It's unfortunate. . . . But if people are planting new trees, I think there are a lot more responsible choices."

Others go a bit further. Shephard wants people to consider how much easier it would be to remove invasive seedlings from parks when they are still as yankable as weeds.

"It's a lot easier to deal with this now," he said.

Airport Heights resident David Gardner, a city project manager trained as a landscape architect, planted his own May Day tree in 1980 at the corner of his house. It eventually grew as high as the roof, shading his deck, drawing birds.

Gardner liked his tree too - until he realized a few years ago that scores of little May Day trees were consuming park land just outside his back fence.

They were spreading like a "shotgun splatter" - seeded by birds. "And it was all from my tree," he said.

So Gardner trimmed his May Day tree into a shrubby trunk and hacked down the invasive seedlings outside his fence. He plans no more May Day trees in any new parks or municipal projects he designs.

"I would urge people to discontinue planting them - or at least trim back the flowers so they don't become berries," he said.

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