With a newly opened floodplain on the Dungeness River, the Jamestown S’Klallam Tribe and local college students are using the space to study floodplain vegetation restoration techniques.
Students with Peninsula College and Western Washington University’s Huxley College of the Environment on the Peninsulas spent a Saturday in February planting more than 300 seedlings of native trees and shrubs, and broadcasting alder seed by hand.
Huxley professor Jenise Bauman approached the tribe about collaborating on a project to study planting techniques in the new space.
“The college’s plot study is a good way to look at a variety of methods for floodplain restoration and help determine which works best, including doing nothing at all or using certain types of plants or seeds,” said Hilton Turnbull, the tribe’s habitat program biologist.
After a major storm damaged a 570-foot-long old wooden trestle over the river in February 2015, the tribe was able to quickly secure funding and a contractor to replace it with a 750-foot-long steel walkway. The old trestle was supported by 185 creosote pilings, blocking the river’s ability to flow into the floodplain.
With the new trestle, supported by just four large concrete piers, the river’s floodplain is now wide open and ready to support salmon habitat. High flows from recent winter storms already have spilled over the riverbanks and into small side channels under the new walkway.
The new floodplain area was divided into three sections, with four treatments in each section: nothing (control); broadcasting alder seed; broadcasting alder seed and planting bareroot seedlings of trees and shrubs; and just planting seedlings of bareroot trees and shrubs. The plantings will be monitored the next few years by Bauman’s students to see how the plants fare.
Students planted native vegetation, such as Oregon grape, ocean spray, Nootka rose, salmonberry and snowberry, which will help support salmon habitat. They’ll stabilize soils in the floodplain and prevent erosion of the riverbank. As the trees grow and fall into the river, they will provide refuge for migrating salmon.
“The replacement of the old trestle and opening up the floodplain allows the river to move back and forth like it should, while giving the river breathing room,” Turnbull said. “The new walkway gave the river space, allowing for better salmon habitat to develop.”