On a recent sunny Saturday, Jean Spohn used a hand saw to cut into the one-inch stem of a perfectly healthy, leafy green plant.

Spohn then pulled up the roots of the plant and tossed them aside. Over 15 minutes, she cleared the same plants from a three-foot ring around the thick gray trunk of a century-old big leaf maple tree.

Standing back, Spohn smiled at the destruction she had wrought in the forest of the Walker Preserve in Normandy Park.

While clearing vegetation may seem like a contradictory way to help the environment, Spohn was working on a project to control English ivy.

"English ivy is an imported, invasive plant that could destroy our urban forests if we do nothing about it," she said.

Removing ivy from the base of native trees is the first step in saving local forests across Highline.

Ivy clearing is an example of the type of local stewardship opportunities people can volunteer for this Saturday, April 19, to show their commitment to Earth Day.

Projects include:

Ivy removal at Des Moines Creek Park in Des Moines, Marine View Park in Normandy Park and Shorewood Park in Burien.

Invasive weed removal and tree mulching on Miller Creek in Burien.

General cleanup and weeding around the Des Moines Marina.

Clearing a vacant lot of debris and graffiti at the North SeaTac Community Center.

And weeding and mulching at two sites on the Duwamish River in north Tukwila.

(See sidebar for contact information to learn more about specific projects and sign up.)

As Spohn and 10 other volunteers worked among the trees along Walker Creek last month, they found ivy vines as thick as three inches in diameter strangling native trees like maple and Douglas fir.

Sometimes volunteers could hear a quiet "snap" as tension was released when they sawed through the vines encircling the trees.

On some trees, ivy had climbed 75 feet high up the trunk. When ivy reaches that high up a tree, she explained, it increases the weight hanging on the tree and expands "sail area."

In winter storms, strong winds topple ivy-incrusted trees more easily than healthy trees free of ivy. If ivy already covers the surrounding forest floor, it makes it difficult for native trees to grow back.

The unchecked spread of ivy also could kill trees along neighboring Walker Creek, home to coho and chum salmon and cutthroat trout. Native trees along the stream provide shade to keep the water cool.

They also create a home for insects that fall into the stream and provide food for the fish.

And if these ivy-caused problems aren't enough to get your attention, Spohn added with a laugh, "Ivy also provides a good home for rats!"

Stewardship Needed Year Round

Most of the projects that offer volunteer opportunities this Saturday are not one-time events.

While Spohn recently volunteered to remove ivy at the Walker Preserve, she also organizes monthly work parties of her own to control ivy at Shorewood Park in Burien.

"We hope that lots of new volunteers will come out on April 19 and learn about the important work that's going on to improve the health of our environment and our community in general," said Spohn.

"People will experience for themselves how satisfying it is to work alongside their neighbors to improve their little part of the world and decide they want to help out again."

Stewardship work parties occur across the Highline area throughout the year, with the number peaking in the spring and fall.

Spring is good time to control emerging weeds. Ivy is easy to see and reach when the deciduous trees haven't fully leafed out.

While some tree planting occurs in the spring, autumn is the preferred time for planting native trees and shrubs because less watering is needed.

After three hours of laboring on March 22, the volunteers had succeeded in clearing ivy from around nearly all the trees in the preserve.

Their work is part of a larger plan to improve the Walker Preserve - a public park owned by the city of Normandy Park.

On June 7, volunteers will return to clear the remaining ivy from inside a loop trail.

In the fall, evergreen trees such as western red cedar and spruce will be planted in the cleared area to improve the diversity of the forest.

These efforts also will improve the forest's ability to absorb carbon dioxide - a gas that is believed by many to contribute to global warming.

Normandy Park Councilman Clarke Brant was one of the volunteers who ended the morning workout tired and dusty but happy to have helped.

"I'm glad I volunteered. Sometimes environmental problems seem overwhelming," Brant said.

"But when you actually do something like this with a bunch of other people, you realize that you can solve even difficult problems by working together, one step at a time."

Dennis Clark is the half-time Miller and Walker Creek Basin Steward. Burien, Normandy Park, SeaTac, the Port of Seattle, and King County jointly fund his work. Contact him at 206-296-1909 or dennis.clark@kingcounty.gov.