Caring for this iconic Columbia River island requires vigilance...and some heavy equipment.
This spring, Columbia Land Trust’s stewardship team spent a lot of time plying the waters between Beacon Rock State Park and Pierce Island. They hauled chippers and chainsaws and propane torches—machinery needed to battle desert false indigo (Amorpha fruticosa). The noxious weed with woody stems and a bushy appearance had colonized an 85-acre footprint on the island, outcompeting native vegetation and choking the island’s gravelly shores.
Desert false indigo had to go. Removing the invader was the first of many restoration projects Columbia Land Trust has planned for Pierce Island. In July, the Nature Conservancy transferred Pierce to our care—and also furnished a $120,000 endowment that will allow us to improve Pierce Island’s habitat. That includes black cottonwood–Oregon ash forest, an important type of woodland that provides perching and nesting sites for eagle and osprey. “We want to return some of the historic habitat complexity back to the land,” says Stewardship Director Ian Sinks. “That will benefit a wide variety of wildlife species—both on shore and in the river.”
Pierce Island is habitat for several species that don’t thrive in many other places, among them persistent sepal yellowcress (Rorippa columbiae), a Washington State–endangered plant that likes Pierce Island’s gravelly shores. “This is one of only two areas left in the state where this little-seen botanical treasure exists,” says Columbia Land Trust’s Forestry Initiative Manager Cherie Kearney.
Pierce Island’s shore and surrounding waters are important spawning, rearing and feeding habitat for chum and Chinook salmon. Though not as celebrated as Chinook, chum—also known as “dog salmon”—are in serious peril. The annual estimated Columbia River chum run is just 3,000 to 4,000, compared to an historic estimate of some 1.4 million. Once found in nearly every major Columbia River tributary, as well as at sites throughout the river’s main stem, today chum are limited to only two significant population areas in the entire lower Columbia River.
One of those areas happens to be Hamilton Creek, whose waters empty directly across from Pierce Island’s neighbor, Ives Island. Chum and Chinook even spawn in spots around the rocky perimeters of the islands.
Caring for a Columbia River island requires constant monitoring and on-the-ground management: The river’s changing flows reliably deposit a steady supply of unwanted weed seeds as well as garbage ranging from beer cans to fishing line to fences. Elk, which swim to Pierce Island from the mainland, can decimate new plantings. The whole island can shift in shape and size.
While Pierce Island’s future is not entirely up to Columbia Land Trust (subject as it is to water’s powerful forces), we will be working to ensure it can continue to support a thriving diversity of life. —Columbia Land Trust staff