Invalid Unit Specified
D027 Abronia spp. - Leymus mollis ssp. mollis - Erigeron glaucus Pacific North American Coastal Scrub & Herb Vegetation Division

The U.S. National
Vegetation Classification
Type Concept Sentence: This division is comprised of sparsely- to well-vegetated rocky headlands, sea bluffs, beaches and dunes along the Pacific Coast of North America that are dominated by prostrate perennials on the beach and foredune, and by graminoids and scrub on backdunes and bluffs.
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Common (Translated Scientific) Name: Sand-verbena species - American Dunegrass - Seaside Fleabane Pacific North American Coastal Scrub & Herb Vegetation Division
Colloquial Name: Pacific North American Coastal Scrub & Herb Vegetation
Hierarchy Level: Division
Type Concept: This division consists of sparsely- to well-vegetated herbaceous and shrubby vegetation on coastal sandy and cobble-on-sand beaches, beach dunes, sand spits, sea cliffs, scree slopes and rocky bluffs exposed to wind, salt spray and occasional ocean wave action, from the coast of the Aleutian Islands, south through California and into northern Mexico. Herbaceous communities on beaches, spits and nearby dunes are characterized by Abronia latifolia, Abronia maritima, Artemisia pycnocephala, Atriplex leucophylla, Carex macrocephala, Eriophyllum stoechadifolium, Isocoma menziesii, Leymus mollis ssp. mollis, Honckenya peploides ssp. major, Lathyrus japonicus var. maritimus, or Senecio pseudoarnica. Stabilized backdunes are often dominated by shrub or dwarf-shrub communities with Empetrum nigrum, Gaultheria shallon, Lupinus chamissonis, or Vaccinium ovatum. Introduced species flourishing on these sites are Cakile edentula and Cakile maritima (on the beaches) and Ammophila arenaria (on dunes). On rocky headlands, sea bluffs and cliffs, the dominant vegetation varies over the latitudinal range. Lichen cover can be high. The vascular vegetation is typically composed of grasses and low shrubs, which are restricted to small cracks in rock, or slight, sheltered depressions. In the north, dominants include Aruncus dioicus var. acuminatus, Carex macrochaeta, Chamerion latifolium, Deschampsia spp., Fragaria chiloensis, Heuchera glabra, Lupinus nootkatensis, Potentilla villosa, Prenanthes alata, and Rhodiola rosea. Coastal bluffs further south, in the Georgia Strait and Puget Sound areas, have Festuca rubra as a common dominant with associated species such as Bromus sitchensis, Grindelia integrifolia, Heuchera micrantha, Juniperus maritima, Plectritis congesta, Sedum spp., and Zigadenus venenosus. Introduced species are often present, e.g., Aira spp., Cynosurus echinatus, and Cytisus scoparius. Coastal bluff-scrub on the California coastal islands has Artemisia californica, Coreopsis gigantea, Dudleya caespitosa, Dudleya greenei, Eriogonum arborescens, Eriogonum giganteum, Eriogonum grande var. rubescens, Isocoma menziesii, Malacothrix saxatilis var. implicata, and many others, including many endemic species. The northern Baja and Sonoran coasts of the Gulf of California are typically composed of prostrate shrubs and succulents that can withstand salt spray and saline soils, as well as seasonal drought. Common species include Amaranthus watsonii, Nicotiana obtusifolia, Ficus spp., Hofmeisteria spp., Eucnide rupestris, Pleurocoronis laphamioides, and Maytenus phyllanthoides.
Diagnostic Characteristics: The herbaceous and shrubby vegetation of this division is restricted to sites immediately adjacent to the Pacific Coast that are exposed to wind, salt spray, and occasional ocean wave action. Sites include beaches, spits, dunes, sea bluffs, sea cliffs and rocky headlands. Total cover varies from very low on beaches, active dunes and rocky headlands, to moderately dense on stabilized dunes and sea bluffs. Graminoid or broad-leaved herbaceous vegetation is most characteristic, but some dwarf-shrub and low-shrub vegetation occurs. On the sandy beaches and dunes, plants are generally rhizomatous or stoloniferous. Strong diagnostic species include salt-tolerant forbs such as Abronia latifolia, Abronia maritima, Artemisia pycnocephala, Atriplex leucophylla, Dudleya caespitosa, Eriophyllum stoechadifolium, Fragaria chiloensis, Grindelia integrifolia, Isocoma menziesii, Honckenya peploides ssp. major, Lathyrus japonicus var. maritimus, Mertensia maritima, Plectritis congesta, and Senecio pseudoarnica. Grasslands are characterized by Leymus mollis ssp. mollis, Carex macrocephala, Ericameria ericoides, Eriogonum giganteum, or Festuca rubra. Characteristic shrubs include Coreopsis gigantea and Juniperus maritima. Salt-tolerant introduced species are common.
Rationale for Nominal Species or Physiognomic Features:
Classification Comments: The plant species of this division show latitudinal and climatic variation, from the near desert conditions of the Baja, to the Mediterranean climates of California, to the temperate coast of Oregon, Washington, British Columbia, and the boreal transition of Alaska. The northern limit of this division is likely best characterized by the northern boreal and arctic climates where Honckenya peploides ssp. diffusa replaces Honckenya peploides ssp. major, and Leymus mollis ssp. villosissimus replaces Leymus mollis ssp. mollis. Mertensia maritima occurs throughout the northern boreal and arctic coast, but also runs south along the coast of southeastern Alaska and Haida Gwaii (Queen Charlotte Islands). At the southern end, this division extends to the Viscaino Peninsula in central Baja. South of here, and on the littoral of much of the Sea of Cortez, the vegetation is more truly tropical: there is very little Abronia spp. and there are more pan-tropical littoral genera or species such as Scaevola, Cocos, or Ipomoea pes-caprae, and several species of mangroves. The coastal sand dunes there also have tropical grasses such as Jouvea pilosa.
Similar NVC Types:
D035 Temperate & Boreal Pacific Coastal Salt Marsh, note: includes salt-tolerant coastal vegetation of the inter-tidal zone (i.e., estuarine vegetation).
D146 Arctic Coastal Scrub & Herb Vegetation, note: includes coastal vegetation in boreal and arctic regions to the north of D027.
D052 Western North American Temperate Cliff, Scree & Rock Vegetation, note:
D022 Western North American Grassland & Shrubland, note: includes upland grassland and shrubland vegetation further inland from the coastal vegetation of D027.
D031 Western North American Temperate Freshwater Marsh, Wet Meadow & Shrubland, note: includes freshwater wetland vegetation over the range of D027, but mostly further inland.
Physiognomy and Structure: Vegetation is generally comprised of creeping to low-statured perennial grasses, forbs, succulents, or dwarf-shrubs. Plants of beaches and dunes are usually rhizomatous or stoloniferous. Total cover varies from very low on beaches, active dunes and sea cliffs to moderately dense on stabilized dunes and sea bluffs. Lichen or moss cover can be high on sea cliffs and rocky headlands. Dense shrublands can occur on stabilized dunes. Stunted trees can occur, clinging to cliff faces, bluffs and balds exposed to salt spray of the ocean.
Floristics: The vegetation on beaches, spits and dunes consists of communities of salt-tolerant forbs and grasses. In northern areas, sites are dominated by species such as Achillea millefolium var. borealis, Carex macrocephala, Cochlearia groenlandica, Honckenya peploides ssp. major, Lathyrus japonicus var. maritimus, Leymus mollis ssp. mollis, Mertensia maritima, and Senecio pseudoarnica. In central and southern areas, the sites are dominated by Ambrosia chamissonis, Abronia latifolia, Abronia maritima, Atriplex leucophylla, Artemisia pycnocephala, Eriophyllum stoechadifolium, Isocoma menziesii, Lupinus arboreus, as well as Leymus mollis ssp. mollis. Common associates include Camissonia cheiranthifolia (= Camissoniopsis cheiranthifolia), Ericameria ericoides, Erigeron glaucus, Lupinus arboreus, Lupinus chamissonis, Lupinus littoralis, and Polygonum paronychia. Non-native species can dominate the vegetation in some areas, e.g., Ammophila arenaria is a common dune grass; Cakile edentula and Cakile maritima occur on beaches. Further south, into Baja California, Mexico, sites are composed of Abronia maritima, Astragalus anemophilus, Atriplex canescens var. linearis, Atriplex julacea, Atriplex magdalenae, Chaenactis lacera, Croton californicus, Encelia ventorum, Euphorbia misera, Frankenia palmeri, Helianthus niveus, Lotus bryantii, Lycium californicum, Lycium brevipes (= Lycium richii), Maytenus phyllanthoides, and Suaeda taxifolia. Dwarf-shrub communities on stabilized dunes are dominated by Empetrum nigrum, Gaultheria shallon, or Vaccinium ovatum.

Sea bluffs, sea cliffs and rocky headlands are characterized by a mix of forbs, grasses and shrubs. On sea cliffs and headlands, vascular plants establish on ledges and in cracks. Mosses can be abundant on rock bluffs; lichens can dominate rocky headlands and cliffs. The vegetation varies considerably from north to south. On the Alaska Peninsula, common species are Alnus viridis ssp. sinuata, Aruncus dioicus var. acuminatus, Campanula spp., Carex macrochaeta, Chamerion latifolium, Deschampsia spp., Fragaria chiloensis, Heuchera glabra, Lupinus nootkatensis, Phegopteris connectilis, Potentilla villosa, Prenanthes alata, and Rhodiola rosea. On Haida Gwaii, Festuca rubra is a common dominant of rocky headlands, with associated species including Achillea millefolium, Conioselinum gmelinii, Fragaria chiloensis, Maianthemum dilatatum, Mimulus guttatus, Plantago maritima, Potentilla villosa, and stunted Picea sitchensis.

Coastal bluffs further south (Georgia Strait and Puget Sound areas) also have Festuca rubra but associated species include Grindelia integrifolia, Heuchera micrantha, Plectritis congesta, Sedum spp., and Zigadenus venenosus. Juniperus maritima may also occur. Mosses can be abundant, including Racomitrium canescens, Polytrichum piliferum, or Dicranum spp. Introduced species are often found, e.g., Aira spp., Cynosurus echinatus, and Cytisus scoparius.

Coastal bluff-scrub on the California coastal islands has species such as Artemisia californica, Coreopsis gigantea (= Leptosyne gigantea), Dudleya caespitosa, Dudleya greenei, Eriogonum arborescens, Eriogonum giganteum, Eriogonum grande var. rubescens, Isocoma menziesii, and Malacothrix saxatilis var. implicata.
Dynamics: Sites are subject to exposure to waves, eroding and desiccating winds, slope failures, and sheet erosion.
Environmental Description: This division occurs on sandy beaches, spits, dunes, rocky headlands, bluffs and sea cliffs found along the coast, where wind exposure and salinity are major drivers of the vegetation, with occasional wave action playing a role on beaches and spits. The dunes can extend inland from the sea to wherever the wind and sandy/gravelly site conditions restrict tree growth. Although these communities typically occur at low elevations, salt spray from winter storms may affect exposed cliffs at 100-200 m elevation.

Climate: Much of the vegetation of this division is influenced by a broadly temperate maritime climate; however, in the south, the climate is Mediterranean.

Soils/substrate: Soils of beaches and spits and dunes are usually sandy and well-drained, although some areas may have a cobble layer on top of sand. Rocky headlands, cliffs and sea bluffs generally have thin soils that are limited to fine materials blown into cracks and fissures in the bedrock substrate.

Biogeography: The vegetation of this division does vary over the wide latitudinal range. Cold-temperate, warm-temperate and Mediterranean climates are included, and the floristics differ somewhat in each of these regions. Peinado et al. (2009, cited in Peinado et al. 2011a) have distinguished seven phytogeographical provinces over the range of this division: Aleutian, Sitkan, Oregonian, Northern Californian, Southern Californian, Martirense, and Baja Californian. Peneido et al. (2011a) also assign one of 15 phytogeographical elements to each species in their vegetation tables so it is possible to understand the biogeography of the vegetation units.
Geographic Range: This division occurs along the coastline and islands from the Aleutian Islands south through Alaska's central and southeastern coastline, British Columbia, Washington, Oregon, California and into Mexico to the Viscaino Peninsula.
Nations: CA,MX,US
States/Provinces: AK, BC, CA, MXBCN, OR, WA
US Forest Service Ecoregions (2007)
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Plot Analysis Summary:
Confidence Level: High
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Grank: GNR
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Synonomy: < Beach and Dune (Barbour et al. 2007a)
Concept Author(s): M. Peinado, F.M. Ocaña-Peinado, J.L. Aguirre, J. Delgadillo, M.�. Macías, and G. Díaz-Santiago (2011a)
Author of Description: D. Meidinger
Acknowledgements: Gwen Kittel
Version Date: 29Oct2015
  • Barbour, M. G., T. Keeler-Wolf, and A. A. Schoenherr, editors. 2007a. Terrestrial vegetation of California, third edition. University of California Press, Berkeley.
  • Faber-Langendoen, D., J. Drake, S. Gawler, M. Hall, C. Josse, G. Kittel, S. Menard, C. Nordman, M. Pyne, M. Reid, L. Sneddon, K. Schulz, J. Teague, M. Russo, K. Snow, and P. Comer, editors. 2010-2019a. Divisions, Macrogroups and Groups for the Revised U.S. National Vegetation Classification. NatureServe, Arlington, VA. plus appendices. [in preparation]
  • Peinado, M., F. M. Ocaña-Peinado, J. L. Aguirre, J. Delgadillo, M. Ã�. Macías, and G. Díaz-Santiago. 2011a. A phytosociological and phytogeographical survey of the coastal vegetation of western North America: Beach and dune vegetation from Baja California to Alaska. Applied Vegetation Science 14:464-484.
  • Peinado, M., M. Ã�. Macías, J. L. Aguirre, and J. Delgadillo. 2009b. Fitogeografía de la costa del Pacífico de Norteamérica. Anales del Jardín Botánico de Madrid 66(2):1-44.