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CEGL001660 Pseudoroegneria spicata Grassland

Type Concept Sentence: No Data Available

Common (Translated Scientific) Name: Bluebunch Wheatgrass Grassland

Colloquial Name: No Data Available

Hierarchy Level:  Association

Type Concept: This grassland association occurs on rock outcrops, talus, mesas, plateaus, windswept bluffs, ridgetops and mountains in northern Colorado, northeastern and northern Utah and western and southwestern Wyoming. It frequently occurs on moderately to steep, mid- to high-slope landforms, although gentle slopes are not uncommon. Sites are relatively xeric and are often found on southerly aspects at lower elevations or on harsh or on windswept areas at higher elevation sites. Substrates are typically shallow, often calcareous, rocky soils. Ground surface often has significant cover of bare ground, gravel and/or rock (10-90% cover). Stands are also reported east of the Continental Divide in Rocky Mountain National Park on a windward knoll and at Grand Teton National Park from a very steep northeast-facing high slope. The vegetation is characterized by an open herbaceous layer that is typically dominated by the cool-season, perennial bunchgrass Pseudoroegneria spicata with low to moderate cover (5-30%) and low-growing forbs. Koeleria macrantha is repeatedly present in low abundance. Other dry grasses may be present with low cover (less than half the cover of Pseudoroegneria spicata). A sparse dwarf-shrub layer (<10% cover) occurs with a variety of woody species of Artemisia, Atriplex confertifolia, Cercocarpus, Eriogonum, Gutierrezia, Krascheninnikovia or Tetradymia depending on elevation and substrate. There are several to many low-growing forbs (cushion plants) present with low cover, such as Arenaria spp., Arenaria hookeri, Astragalus spp., Paronychia sessiliflora, Phlox spp., Stenotus acaulis, Tetraneuris acaulis, and Townsendia incana. There are no clear dominants in this list, and the percent cover of each species present will vary from site to site. A diverse and abundant forb layer probably indicates a degraded occurrence.

Diagnostic Characteristics: No Data Available

Rationale for Nominal Species or Physiognomic Features: No Data Available

Classification Comments: This association needs to be compared with ~Pseudoroegneria spicata - Cushion Plants Grassland (CEGL001666)$$ of Pryor Mountains and Bighorn Canyon in south-central Montana, the Tendoy Mountains in southwest Montana and as described in Dinosaur National Monument in northwestern Colorado. It is distinguished by its lack of significant cover by cushion plants. Both associations occur on windswept ridgelines on calcareous substrates, have relatively sparse vegetation cover and contain cushion plants. The range of this association needs further review, especially disjunct stands, because the diagnostic grass in this association can be readily confused with awned Elymus lanceolatus (note if rhizomes are present, whereas Pseudoroegneria spicata has no rhizomes). Also Pseudoroegneria spicata ssp. inermis (awnless) is often confused with Pascopyrum smithii (note asymmetrical glume) or other wheatgrasses.

Similar NVC Types: No Data Available
note: No Data Available
Physiognomy and Structure: No Data Available

Floristics: This association is characterized by an open vegetation layer that is typically dominated by the cool-season, perennial bunchgrass Pseudoroegneria spicata with low to moderate cover (7-30%) and low-growing forbs. Koeleria macrantha is repeatedly present in low abundance. Other grasses may include Achnatherum hymenoides, Hesperostipa comata, Poa fendleriana, and Poa secunda; if present, they have low cover (less than half the cover of Pseudoroegneria spicata). A sparse dwarf-shrub layer (<10% cover) may be present and includes a variety of woody species, such as Artemisia arbuscula ssp. longiloba, Artemisia frigida, Artemisia nova, Artemisia tridentata, Atriplex confertifolia, Cercocarpus intricatus, Cercocarpus montanus, Chrysothamnus greenei, Chrysothamnus viscidiflorus, Ericameria nauseosa, Eriogonum corymbosum, Eriogonum microthecum, Gutierrezia sarothrae, Krascheninnikovia lanata, Rosa woodsii, Ribes cereum, Symphoricarpos oreophilus, or Tetradymia canescens, depending on elevation and substrate. Several to many low-growing forbs (often cushion plants) are present with low cover but not codominant. Species may include Arenaria fendleri, Arenaria hookeri, Astragalus jejunus, Astragalus spatulatus, Astragalus tenellus, Chaetopappa ericoides, Draba oligosperma, Eriogonum lonchophyllum, Heterotheca villosa, Linanthus pungens (= Leptodactylon pungens), Lesquerella alpina, Linum lewisii, Machaeranthera grindelioides, Mertensia oblongifolia, Paronychia sessiliflora, Penstemon paysoniorum, Phlox austromontana, Phlox hoodii, Sphaeralcea coccinea, Stenotus acaulis, Tetraneuris acaulis (= Hymenoxys acaulis), Townsendia incana, and Trifolium gymnocarpon. There are no clear dominants in this list, and the percent cover of each species present will vary from site to site. A diverse and abundant forb layer probably indicates a degraded occurrence (R. Rondeau pers. comm. 1998). Introduced species such as Agropyron cristatum, Bromus briziformis, or Bromus tectorum are present in some stands.

Dynamics:  Wind appears to be an important factor in many stands of this association, by removing snow in the winter and rendering sites too dry to support shrublands. Grazing has a negative effect on this association, and it is believed that it now occupies a very small portion of the original range. Pseudoroegneria spicata does not tolerate grazing and will eventually convert to a Koeleria macrantha or Poa secunda grassland if grazing pressures continue. The stands may also convert to non-native species such as Bromus tectorum under continuous pressure or when combined with other disturbances, such as fire.
Environmental Description:  This herbaceous association occurs in northern Colorado, northeastern and northern Utah, and western and southwestern Wyoming (Hull and Hull 1974, Baker 1982b, Baker and Kennedy 1985). Stands occur on rock outcrops, talus, mesas, plateaus, windswept bluffs, ridgetops and mountains. It frequently occurs on moderate to steep, mid- to high-slope landforms, although gentle slopes are not uncommon. Elevation ranges between 1680 and 2840 m (5500-9310 feet) in Colorado and down to 1340-1590 m (4400-5200 feet) in Utah. Stands reported from Fossil Butte National Monument and Grand Teton National Park occur between 2234 and 2382 m (7328-7810 feet) elevation on well-drained clay soils that are very prone to erosion. Sites are relatively xeric and are often found on southerly aspects at lower elevations or on harsh, steep or windswept areas at higher elevations. Substrates are typically shallow, often calcareous, rocky soils and include sandstone and marlstone of the Uinta and Green River formations, Madison limestone, Mancos shale, Wasatch Formation shale and Morgan/Round Valley and Lodore formations and granite. Ground surface often has significant cover of bare ground, gravel and/or rock (10-90% cover). Evidence of erosion is often present.
Geographic Range: This association occurs in Piceance Basin and Dinosaur National Park in western Colorado and the Cache Valley of northeastern Utah. Stands are reported from Fossil Butte National Monument and Grand Teton National Park in Wyoming and Rocky Mountain National Park in Colorado.

Nations: US

States/Provinces:  CO, MT, NV, UT, WY


Confidence Level: Moderate

Confidence Level Comments: No Data Available
Grank: G2

Greasons: No Data Available
Type Name Database Code Classification Code
Class 2 Shrub & Herb Vegetation Class C02 2
Subclass 2.B Temperate & Boreal Grassland & Shrubland Subclass S18 2.B
Formation 2.B.2 Temperate Grassland & Shrubland Formation F012 2.B.2
Division 2.B.2.Nf Western North American Grassland & Shrubland Division D022 2.B.2.Nf
Macrogroup 2.B.2.Nf.3 Tufted Hairgrass - Licorice-root species - Mountain Muhly Subalpine-High Montane Mesic Meadow Macrogroup M168 2.B.2.Nf.3
Group 2.B.2.Nf.3.a Arizona Fescue - Thurber''s Fescue - Mountain Muhly Grassland Group G268 2.B.2.Nf.3.a
Alliance A3953 Arizona Fescue - Mountain Muhly - Muttongrass Southern Rocky Mountain Montane Grassland Alliance A3953 2.B.2.Nf.3.a
Association CEGL001660 Bluebunch Wheatgrass Grassland CEGL001660 2.B.2.Nf.3.a
Concept Lineage: No Data Available

Predecessors: No Data Available

Obsolete Names: No Data Available

Obsolete Parents: No Data Available
Synonomy: = Agropyron spicatum var. inerme Western Slope Grassland (Baker 1982b)
= Pseudoroegneria spicata - Arenaria hookeri Plant Association (Baker and Kennedy 1985)
= Pseudoroegneria spicata Herbaceous (Jones and Ogle 2000)
< Grassland (Hull and Hull 1974) [This paper refers to Pseudoroegneria spicata-dominated grasslands in protected or moderately grazed areas in the Cache Valley of Utah.]
Concept Author(s): D. Zoellner

Author of Description: D. Zoellner, K.A. Schulz and J. Coles

Acknowledgements: No Data Available

Version Date: 05-06-08
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  • Baker, W. L., and S. C. Kennedy. 1985. Presettlement vegetation of part of northwestern Moffat County, Colorado, described from remnants. Great Basin Naturalist 45(4):747-777.
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  • Erixson, J., and D. Cogan. 2012c. Vegetation inventory project report: Nez Perce National Historical Park. Natural Resource Report NPS/UCBN/NRR--2012/531. National Park Service, Fort Collins, CO. 380 pp.
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  • Stevens, J. E., D. S. Jones, and K. J. Benner. 2015. Vegetation classification and mapping project report: Bighorn Canyon National Recreation Area. Natural Resource Report NPS/GRYN/NRR--2015/1070. National Park Service, Fort Collins, CO. 350 pp.
  • WNDD [Wyoming Natural Diversity Database]. No date. Unpublished data on file. Wyoming Natural Diversity Database, University of Wyoming, Laramie, WY.
  • Western Ecology Working Group of NatureServe. No date. International Ecological Classification Standard: International Vegetation Classification. Terrestrial Vegetation. NatureServe, Boulder, CO.