Invalid Unit Specified
D052 Pseudotsuga menziesii / Umbilicaria spp. - Aspidotis densa Western North American Temperate Rock Vegetation Division

The U.S. National
Vegetation Classification
Type Concept Sentence: This division is characterized by the vegetation of rocky or rock-like habitats, including outcrops, cliffs, talus, or scree, in low- to mid-elevation, temperate and boreal climatic areas of western North America. Cryptogam vegetation tends to dominate, with vascular plants species of low cover.
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Common (Translated Scientific) Name: Douglas-fir / Rocktripe Lichen species - Indian's Dream Western North American Temperate Rock Vegetation Division
Colloquial Name: Western North American Temperate Cliff, Scree & Rock Vegetation
Hierarchy Level: Division
Type Concept: This division occurs throughout temperate and boreal western North America and consists of sparsely to moderately vegetated rock outcrops and cliff faces, talus and scree from the Alaska Peninsula and Aleutian Islands, boreal Alaska, Coast Mountains of British Columbia, the Rocky Mountain Cordillera, Cascades, Sierra Nevada and other ranges tall enough to have a temperate climate. The vegetation is highly variable and is typically a sparse cover of vascular species with sparse to dense cover of lichens, mosses, ferns or fern allies. Characteristic nonvascular species include lichens of the genera Umbilicaria, Rhizocarpon, Stereocaulon, Cladonia, mosses of the genera Tortula, Racomitrium, or Polytrichum, ferns such as Aspidotis densa, Cryptogramma acrostichoides, or Woodsia oregana, or other cryptogams such as Selaginella spp. Overall, the nonvascular species are poorly characterized. Vascular plant species that can survive these harsh environments, e.g., Arctostaphylos spp., Juniperus spp., Penstemon spp., or Sedum spp., or grasses such as Festuca viridula, Poa curtifolia, or Pseudoroegneria spicata, can also occur. In deeper cracks or crevices, where soil accumulates, stunted trees can occur, including Abies concolor, Abies lasiocarpa, Abies magnifica, Pinus albicaulis, Pinus contorta, Pinus flexilis, Pinus monticola, Pinus ponderosa, Pseudotsuga menziesii, Populus tremuloides, Tsuga mertensiana, or Pinus edulis.
Diagnostic Characteristics: Vegetation is characterized by cryptogams (mosses, lichens, ferns and fern allies) with a sparse cover of herbaceous and woody vascular plants on exposed bedrock or talus. Woody plants include various shrub and tree species capable of surviving on these harsh sites. Insufficient information is available regarding diagnostic mosses and other nonvascular species; vascular plants include a range of typical western North American herb, shrub and tree species that are tolerant of the harsh conditions on these sites.
Rationale for Nominal Species or Physiognomic Features:
Classification Comments: Insufficient information is available regarding mosses and other nonvascular species on these sites. The species presented here are based on limited data. The diagnostic species for this division cannot be evaluated with the lack of information on the mosses and lichens; however, the associated vascular flora will certainly differ between this division and other rock vegetation divisions.
Similar NVC Types:
D022 Western North American Grassland & Shrubland, note: includes grassland and shrubland vegetation within the range of D052 that occurs on upland sites with better soil development.
D027 Pacific North American Coastal Scrub & Herb Vegetation, note: "includes vegetation of sea cliffs, scree slopes, rocky bluffs and beaches that are close to the Pacific coast and are exposed to wind, salt spray and occasional ocean wave action."
D051 Eastern North American Temperate Cliff, Scree & Rock Vegetation, note: "includes vegetation of similar habitats but in areas to the east of D052, characterized by a Great Plains flora."
Physiognomy and Structure: The vegetation typically contains a covering of lichens and/or mosses growing on the rock surfaces, usually with some sparse covering of vascular plants, usually growing in soil pockets. The resulting structure and physiognomy is highly variable as it can include scattered trees, shrubs, grasses or forbs along with variable moss and/or lichen cover. Trees and shrubs often grow in dense clumps out of cracks in bedrock and small soil deposits and are often stunted.
Floristics: Characteristic nonvascular species include a variety of foliose and crustose lichens of the genera Umbilicaria, Rhizocarpon, Stereocaulon, Cladina, Cladonia, dry-site mosses of the genera Tortula, Racomitrium, or Polytrichum, ferns such as Aspidotis densa, Cryptogramma acrostichoides, or Woodsia oregana, or other cryptogams such as Selaginella spp. Overall, the nonvascular species are poorly characterized even though they predominate on these sites. Many vascular plants occur on these sites; however, they are mostly of low cover and vigor, as soils are mostly thin or unstable. The species are generally vascular plants that can survive these harsh environments, e.g., Arctostaphylos spp., Ceanothus spp., Juniperus spp., Penstemon spp., or Sedum spp., or certain grasses. The associated vascular flora varies considerably over the range of this vegetation type. In forested landscapes, trees from the surrounding forests can survive on these rocky sites in small pockets of soil or, on talus, where the substrate is relatively stable. Potential trees include the full range of western North American species; however, those of dry sites are most common, e.g., Arbutus menziesii, Pinus albicaulis, Pinus flexilis, Pinus contorta var. latifolia, Pinus ponderosa, Populus tremuloides, Pseudotsuga menziesii, Pinus edulis, Quercus garryana, and Juniperus spp. In moist or high-elevation climates, other tree species can occur, including Abies concolor, Abies lasiocarpa, Pinus monticola, or Tsuga mertensiana.
Dynamics: Talus and scree are subject to ongoing downslope movement. Soil development on outcrops and cliffs is slow and is best developed in fissures where windblown materials accumulate and/or freeze-thaw action eventually results in some finer parent material.
Environmental Description: The division occurs throughout temperate and boreal western North America from the Alaska Peninsula and Aleutian Islands south to the Coast Mountains of British Columbia, the Rocky Mountain Cordillera, Cascades, Blue Mountains, Sierra Nevada and other ranges with sufficient elevation to have a temperate (as opposed to desert) climate. Sites range from moderate to steep slopes on bedrock outcrops, cliff faces, narrow canyons, and talus/scree slopes. Overall, these are dry sites, but wetter climate will somewhat ameliorate the site conditions.

Climate: The climate is typical of temperate and boreal western North America, with considerable range of temperature and precipitation regimes over the type. Temperature regimes vary from maritime to continental, and from warm to cool.

Soils/substrate: On rock outcrops and cliffs, the rock is the dominant substrate, with soil accumulating in cracks or depressions. The small pockets of soil vary in texture and coarse fragments depending upon their genesis. Bedrock types in this division include a full range of geology, including volcanic, igneous (intrusives), sedimentary, and metamorphic bedrock types. In the Cascades and Klamath Mountains thin rocky, ultramafic (peridotite, serpentinite) soils are also common. Scree and talus slopes have surface stones of varying depth and size. They are steep, well-drained sites, with an unstable surface. They may have some soil beneath the rock surface, of varying depth and texture, depending upon bedrock type, slope position, and genesis; however, soil development is limited.

Biogeography: Little is known of the nonvascular flora and its distribution on sites of this division. The upland vegetation within the range of this division spans a wide range of vegetation, from coastal rainforests to grasslands, from dry montane woodlands to interior cedar - hemlock forests to subalpine woodlands. As such, the vascular plants associated with communities of this division will differ over the wide range of ecological conditions.
Geographic Range: This division occurs from the Alaska Peninsula and Aleutian Islands, boreal Alaska, south along the Coast Mountains of British Columbia and southeastern Alaska, then east to the Rocky Mountain Cordillera, and south through the Rocky Mountains, Cascades, Sierra Nevada and other ranges, to the mountains of Texas, New Mexico, Arizona, California and northern Mexico, on mountains tall enough to have a temperate climate.
Nations: CA, MX, US
States/Provinces: AB, AK, AZ, BC, CA, CO, ID, MT, MXBC, NM, NV, OR, TX, UT, WA, WY
US Forest Service Ecoregions (2007)
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Plot Analysis Summary:
Confidence Level: Moderate
Confidence Level Comments:
Grank: GNR
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Concept Lineage:
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Obsolete Names:
Pseudotsuga menziesii / Umbilicaria spp. - Aspidotis densa Western North American Temperate & Boreal Rock Vegetation
Western North American Temperate & Boreal Cliff, Scree & Rock Vegetation
Obsolete Parents:
Synonomy:
Concept Author(s): Faber-Langendoen et al. (2015)
Author of Description: D. Meidinger
Acknowledgements: K.A. Schulz
Version Date: 11Jan2016
References:
  • 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]