Recently GaLTT received a question about best practices for planting native species to prevent soil erosion on the banks above the ocean. Shoreline stability is a problem that will worsen as the effects of climate change affect the stresses put on the land edging the ocean.
While it’s difficult to answer in detail without knowing the specifics of a site (e.g., soil moisture, aspect, exposure), here are some general principles landholders can follow.
Don’t plant invasive species!
Check the status of any non-native plants you are considering.
Plant a mix of vegetation types
Sites with a wide variety of vegetation of various ages (groundcovers, shrubs, trees of deciduous and evergreen species) are usually stable, because each plant from large to small contributes to the stabilization of the soil in different ways that come together to form a strong mat.
Plant native species
Generally, a mix of native species including deep rooted shrubs and grasses with fibrous surface roots would work well. Suitable shrubs would include roses (baldhip or Nootka), ocean spray, Oregon grape, evergreen huckleberry, snowberry and kinnikinnick. Salal is salt-tolerant.
Dune grass and oat-grass are grass options. Look for native plant seed mixes that include perennial grass and forb mixtures. (Forbs are herbaceous plants that aren’t grass, sedges, or rushes, the category includes “wildflowers.”)
Trees are excellent for stabilizing slopes; local options would include Douglas-fir, arbutus, shore pine, Douglas maple, and bigleaf maple. Many people are concerned about losing their view—but appropriate planting and pruning can save both the view and reduce damage to slopes and shoreline.
On highly erodible foreshores vegetation might not be enough to solve all problems, but it’s a critical component. And remember: one of the great benefits of using native species in plantings is that they usually require less watering once established.
More information
There’s a lot of information out there on this subject, some of it highly technical. Here are a few starter resources.
- Washington State University’s “Shore Stewards Guide for Shoreline Living” (pdf download) gives a good overview.
- Greenbelt Consulting provides a lot of easy-to-read articles relating to this subject (and much more!):
- Habitat Acquisition Trust has an excellent plant selection guide that covers our area: “Gardening With Native Plants“
- Washington King County’s “Marine Shoreline Planting Guide” has a graphic showing where to plant things for best results.
