No. 27. Coastal Headlands and Islets

Christopher B. Chappell and David H. Johnson

Geographic Distribution. This shrubland, grassland, and nearshore rocky island habitat occurs along slopes and exposed headlands along the outer coast, from Cape Flattery, Clallam County, Washington, southward to (and beyond) California. On small islands it also extends into the Strait of Juan de Fuca and the inland marine waters of Puget Sound and Hood Canal, Washington. Sporadic along the Washington coast (absent between Point Grenville and Cape Disappointment), this habitat becomes most extensive on the southern Oregon coast.

Physical Setting. Wind is extreme in this environment and, in combination with abundant salt-spray, limits tree growth. Fog is common in the summer. Climate is generally mild and moist to wet, with mean annual precipitation ranging from about 70 to 120 inches (178 to 305 cm). Elevation is sea level to about 500 ft (152 m). This habitat occurs mainly on coastal headlands, bluffs, and islands with steep slopes or cliffs. Soils are typically shallow to bedrock or consist of exposed glacial deposits on steep erodable bluffs. Slopes range from gentle to very steep. In some areas, seeps create moist to wet micro-sites.

Landscape Setting. This habitat is always located adjacent to, or in the case of the rock islets ("sea stacks"), within the Marine Nearshore habitat. It is found mainly along the outer coastline where it typically occupies small areas between the Marine Nearshore and Westside Lowland Conifer-Hardwood Forest or on small islands. Cliffs are a common feature. In far southern Oregon (Curry County), it occupies continuous ocean-facing slopes for many miles. Land use is recreation or low-density residential.

Structure. This habitat is a shrubland, grassland, forbland, rocky island, or often a mosaic of these. The dominant shrubs may be tall or short and composed of evergreen or deciduous broadleaf shrubs. Native grasses can be short or up to 5 ft (1.5 m) in height and rhizomatous or cespitose. Forbs or ferns dominate some patches. Coniferous trees are sometimes scattered, occur in small clumps, or form dominant patches of short wind-blasted individuals.

Composition. Shrublands are dominated by salal (Gaultheria shallon), evergreen huckleberry (Vaccinium ovatum), salmonberry (Rubus spectabilis), black twinberry (Lonicera involucrata), California wax-myrtle (Myrica californica), thimbleberry (Rubus parviflorus), or the dwarf shrub, crowberry (Empetrum nigrum). Deer brush (Ceanothus integerrimus) and hairy manzanita (Arctostaphylos columbiana) become important on the southern Oregon coast, as does the non-native gorse (Ulex europaeus). Sitka spruce (Picea sitchensis) is the most common tree, although western hemlock (Tsuga heterophylla), Douglas-fir (Pseudotsuga menziesii), or red alder (Alnus rubra) also may occur. Native dominant grasses are red fescue (Festuca rubra) or Nootka reedgrass (Calamagrostis nutkaensis). Blue wildrye (Elymus glaucus), California danthonia (Danthonia californica), and Sitka brome (Bromus sitchensis) can also be important. A diversity of forbs occurs, with some of the most prominent being Canada goldenrod (Solidago canadensis), Martindale’s lomatium (Lomatium martindalei), giant vetch (Vicia gigantea), giant horsetail (Equisetum telmateia), and coastal wormwood (Artemisia suksdorfii). Bracken (Pteridium aquilinum) is a fern that often co-dominates. Southern Oregon has a number of unique herbaceous species.

Other Classifications and Key References. Franklin and Dyrness ⁸⁸ described portions of this habitat as oceanfront communities on northern Oregon headlands and the southern Oregon coast. The Oregon Gap II Project ¹²⁶ and Oregon Vegetation Landscape-Level Cover Type ¹²⁷ that would represent this type is coastal strand. The Washington Gap project mapped parts of this habitat as coastline, sandy beaches, and rocky islands. Other important references describe elements of the habitat ^{7, 63, 177, 183}.

Natural Disturbance Regime. Wind may topple trees if they do attain upright stature. Charcoal in the soil at some sites in Oregon suggests that this habitat may have had occasional fires in the past ¹⁸³.

Succession and Stand Dynamics. Little is known about the dynamics of this habitat. Trees slowly invade some areas of this habitat. As they do so, herbaceous or shrub-dominated vegetation declines. Fires would favor maintenance of grasslands or forblands.

Effects of Management and Anthropogenic Impacts. Livestock grazing of the grasslands results in decreasing importance of native grasses, especially bunchgrasses, and increasing importance of exotic species. Sweet vernalgrass (Anthoxanthum oderatum), common velvetgrass (Holcus lanatus), and orchardgrass (Dactylus glomerata) are major exotic grass species that dominate significant areas. Gorse has invaded large areas on the southern Oregon coast.

Status and Trends. This habitat occupies a very small area relative to other habitats in the Pacific Northwest.  Condition of the grasslands is generally poor, with an abundance of non-native species. Grasslands continue to decline in condition and extent over time. Shrublands are probably more stable. Three of 5 plant associations listed in the National Vegetation Classification are considered imperiled ¹⁰, but portions of this habitat have not been described at the association level.