For the second year in a row, the Student Conservation Association (SCA) has sent work crews to help Arboretum gardeners restore sections of the Lake Washington Boulevard corridor. For a combined three weeks in August, the local high-school students will remove invasive plants and spread mulch along Arboretum Creek and in the newly created Loop Trail wetlands.
A year ago, SCA crews helped kick off the corridor restoration project with a four-week work stint. The project was made possible by a generous gift of $275,000 that the Foundation received in spring 2018 from a longtime friend of the Arboretum. This spring, we were delighted when the same donor renewed their commitment to project with a second gift of over $120,000. Along with funding the return of the SCA crews, the money will pay for the salaries of temporary garden staff, materials, and more.
“We’re delighted to have the SCA back again this year!” says Foundation Executive Director Jane Stonecipher. “They are doing wonderful work, enhancing the curb appeal of the Boulevard corridor—and ultimately the health of the Arboretum watershed. We’re also excited to be able to connect these great kids to the professional staff at UW Botanic Gardens and Seattle Parks and Recreation, who give them hands-on training in ecological restoration.”
Seattle Parks staff will supervise the work in the Loop Trail wetlands (near the Birch Parking Lot), where the students will be removing weeds such as bittersweet nightshade and hedge bindweed, and then mulching around the native plants that were installed as part of the 520 mitigation. University staff will supervise the work along the creek in the Pinetum, where the students will be mostly battling invasive Himalayan blackberry.
The crews got off to a flying start.
“The wonderful Edmonds SCA crew came and worked with me in the Loop Trail wetlands this past week,” says Matthew Hilliard, a Seattle Parks temporary gardener assigned to the project. “We focused on weed removal, mulching, and native plant seed collection. At first the crew targeted hedge bindweed in the big open part of the wetlands. After that they removed Himalayan blackberry, bittersweet nightshade, and other pernicious weeds from the wetlands section along Lake Washington Boulevard and spread a thick layer of mulch to suppress weeds, insulate soil moisture, and enhance the soil health.”
“Then we switched gears and started doing in-stream weed removal,” continues Matthew, “as the time window recommended by the Washington Department of Fish and Wildlife for this sort of work is basically the month of August. The students targeted bittersweet nightshade, yellow flag iris, and water cress, which have been steadily amassing in the stream bed and reducing stream flow. I also taught the crew a little bit about native plant seed collection, which is important for propagating more plants and using them for continued re-vegetation of the wetlands. We focused on small-fruited bulrush, and they managed to collect over a gallon of seed. Very impressive!”
“I was utterly amazed at how quickly the crew worked, and the quality of the work they did.”
Matthew’s sentiment was echoed by Remy Mathonet, the UW Botanic Gardens temporary gardener working on the project.
“The Seattle SCA crew helped us take on walls of blackberry along Arboretum Creek just south of the Stone Bridge, says Remy. “The group did a great job of removing the blackberry brambles and creating space for the native, riparian vegetation to fill in. There are two separate project sites that we’ve been working on restoring, and the crew was able to connect the sites, creating a larger patch of healthy habitat. They also focused on pulling bittersweet nightshade, which was clogging up the stream corridor.”
“Next week, the Edmonds SCA crew will revisit an older restoration site along the creek to grub out blackberry regrowth and pull laurel and horse chestnut sprouts. It’s important to maintain sites that have been restored to keep undesirable weeds controlled and to ensure that the native plantings thrive.”
“The SCA crews are accomplishing work that would’ve taken us weeks!,” says Remy. “They have such great energy and are so fun to work with!”
A key take-home lesson for the students about ecological restoration is the importance of continued maintenance and monitoring, especially in the early phases of a project.
“The research shows that you can’t just walk away from initial restoration ecology projects—particularly in urban areas—and expect them to be successful,” says UW Botanic Gardens horticulture manager David Zuckerman. “Having the SCA come back to perform follow-up maintenance after last year’s site prep and consecutive fall and spring planting is huge for us and makes the chances for successful plant establishment increase considerably.”