Restoration work is protecting the city-owned riparian area along the Cozine Creek corridor and hillside behind the McMinnville Police Department building on NE Adams Street. it's an important project in removing growth of an invasive plant species and clearing areas overgrown with blackberries and other weeds.
Restoration began about 18 months ago. Tim Stieber, former Yamhill Soil and Water Conservation District executive director, and I approached Jay Pearson, city parks and recreation director, about partnering on the project. We wanted to remove the invasive weeds and restore the area by planting native trees and shrubs.
YSWCD was especially interested in the project because patches of invasive Japanese knotweed (Fallopia japonica) were growing near the stream but were unreachable behind the 6-foot-tall blackberry brambles.
The Oregon Department of Agriculture identifies Japanese knotweed as a native of Eurasia that was introduced to the United States as an ornamental. These plans, according to ODA, "grow vigorously along roadsides, waste areas, streams and ditch banks; create dense colonies that exclude native vegetation; and greatly alter natural tree regeneration. Established populations are extremely persistent and do not respond to mowing or cutting. Large infestations can be eliminated with approved herbicides, but treatments are costly and time consuming. It poses a significant threat in riparian areas, where it disperses during flood events, rapidly colonizing scoured shorelines, islands and adjacent forest land."
City and YSWCD staffs decided to apply for a small grant from the Oregon Watershed Enhancement Board. We planned to mechanically remove the blackberries, chemically treat and kill the knotweed, and replant the 1.2-acre area with native trees and shrubs. The OWEB small grant program, designed to fund small-scale projects that improve watershed health, is competitive, so it was good news when our proposal was accepted.
Last fall, YSWCD hired a contractor to mow the blackberries with a skid-steer mower, and we removed a small amount of concrete fill that had settled into the bottom areas. Because of the steep slope on part of the site, the Yamhill County corrections crew assisted us, using weed-whackers on hard-to-reach areas. It took more than three days to remove the blackberries and knotweed.
After the first mowing, weeds were allowed to grow back partially. Once green re-growth appeared, it was chemically treated with a herbicide approved for use on stream sides.
Knotweed is particularly invasive and known to re-sprout from small stem segments. Therefore, YSWCD staff decided to pile and burn the mowed plant material before winter flooding could flush plants downstream, preventing establishment of additional invasive patches. In the spring, we re-treated the entire site chemically for the knotweed and blackberries that came back.
For the re-planting portion of the project, district staff and local volunteers potted up bare root plants purchased at the 2011 YSWCD native plant sale and grew them out another year at the Miller Woods native plant nursery. The extra grow-time should make the plants hardier and give them a greater survival rate once they are in the ground.
Sunrise Rotary Club members had been instrumental in successful development of the wetland at Joe Dancer Park, so Pearson asked them for help with re-planting along the Cozine. The club believes this restoration project is another important public improvement of natural resources within the city.
The restoration planting will include Oregon white oak, Douglas fir, big leaf maple, Oregon ash, Nootka rose, Oregon grape, red-flowering currant, Douglas spirea and Pacific ninebark. Also, the area will be seeded with blue wild rye, which typically is used for restoration because of its hardy growth. Plants will be surrounded by chicken wire to protect them from the deer that frequent the area.
Unfortunately, because of the dry fall weather, we were forced to postpone the final planting until early November. Look for public announcements inviting community members to participate in the work party.
And thanks go to all our partners for making this restoration project possible.
Guest writer Marie Vicksta has been a conservation planner with the Yamhill Soil and Water Conservation District for more than two years. She works primarily with private landowners to implement projects that improve water quality, reduce erosion and enhance wildlife habitat.
Submitted photos
The hillside behind the McMinnville Police Department’s parking lot borders Cozine Creek. Patches of invasive Japanese knotweed, upper right, had to be removed carefully. A skid-steer mower, above left, cut down the blackberry brambles and other brush to prepare the site for replanting with native plants and grass.
