Coastal Dunes

Oregon Coastal Dunes
Oregon Coastal Dunes Strategy Habitat Photo Credit: Rebecca Kennison, Creative Commons

Occurring along the Oregon coastline, coastal dunes provide habitat for species that prefer open, sandy habitats with a high degree of disturbance from winds and tides.

 

Ecoregions

Coastal dunes are a Strategy Habitat in the Coast Range ecoregion.

Characteristics

The Coastal Dunes Strategy Habitat includes beaches, foredunes, sand spits, and active to stabilizing back dunes. The vegetation varies from sparse to forested, as influenced by sand scour, deposition, movement, and erosion. Species composition is also influenced by salt spray, storm tidal surges, wind abrasion, and substrate stability. Beaches and sandspits are directly influenced by tidal action and are unvegetated. Foredunes generally have unstable sand and sparse to moderate vegetative cover, including dunegrass, seashore bluegrass, gray beach peavine, large-headed sedge, beach morning glory, yellow sandverbena, and silver burweed. In dunes with greater sand stability, red fescue, seashore lupine, coastal strawberry, beach knotweed, and yarrow are dominant. With plant succession, dunes convert over time to shrublands dominated by salal and evergreen huckleberry and forests dominated by shore pine, then eventually Sitka spruce, western hemlock, and Douglas-fir.

Conservation Overview

Coastal dune communities have been altered dramatically through the introduction and spread of non-native European beachgrass, which outcompetes native vegetation and stabilizes foredunes. The stabilized foredunes block movement of sand inland and artificially accelerate plant succession toward shrubland and forest. Dunes artificially stabilized by European beachgrass have contributed to commercial and residential development of sandy habitats that were once naturally active, moving systems. In Oregon, approximately 90 percent of coastal dunes have been altered from their natural state since 1850.

Species that live in coastal dune habitats prefer open, sandy habitats with a high degree of disturbance from winds and tides. Strategy Species associated with coastal dunes include Western Snowy Plover, pink sandverbena, and Wolf’s evening primrose.

Western Snowy Plovers nest on the beach, making their eggs and young susceptible to disturbance from recreational activities.
Photo Credit: USFWS. Western Snowy Plovers nest on the beach, making their eggs and young susceptible to disturbance from recreational activities.

Limiting Factors and Recommended Approaches

Limiting Factor: Beachgrass Invasion

European beachgrass stabilizes dunes, resulting in changes in vegetative communities and loss of open sandy habitats that are vital to native species.

Recommended Approach

Use mechanical and chemical treatment to control European beachgrass in priority areas, such as Western Snowy Plover nesting areas and near pink sandverbena populations. Build on existing restoration efforts to control beachgrass.

Limiting Factor: Invasive Plants

Stabilized dunes are vulnerable to invasive species, such as Pampas grass, Scotch broom, and gorse, which displace native plants and animals and accelerate succession.

Recommended Approach

Control key invasive plants using site-appropriate tools, such as mechanical (e.g., mowing, girdling, pulling), chemical, and biocontrol (for gorse) treatments.

Limiting Factor: Increasing Development

Stabilized dunes are being developed for residential housing.

Recommended Approach

Use voluntary cooperative approaches, such as financial incentives, Candidate Conservation Agreements with Assurances, and conservation easements to maintain dune habitats. Work with agency partners to support and implement Statewide Land Use Goal 18, Beaches and Dunes.

Limiting Factor: Recreational Impacts

In some areas, recreational use can cause disturbance to wildlife (e.g., Western Snowy Plover nesting areas). Off-highway vehicles can impact vegetation and disturb wildlife.

Recommended Approach

Work with land managers to direct recreational use away from highly sensitive areas. Provide recreational users with information on coastal dune conservation issues and low-impact uses.

Resources for more information