Print Report

CEGL005653 Pascopyrum smithii Central Rocky Mountain Grassland

Type Concept Sentence: Common mesic grassland of the central Rocky Mountains dominated by Pascopyrum smithii.

Common (Translated Scientific) Name: Western Wheatgrass Central Rocky Mountain Grassland

Colloquial Name: Central Rocky Mountain Western Wheatgrass Mixedgrass Prairie

Hierarchy Level:  Association

Type Concept: This midgrass prairie type is found in the central Rocky Mountains, and extends into Canada at elevations from 600-3000 m (1960-9850 feet). Stands occur on level to gently sloping terrain. They are found on alluvial fans, swales, river terraces, floodplains, valley floors and basins. The soils are typically clay, clay loam, and silt loam but may include sand or loamy sand. Pascopyrum smithii strongly dominates the open to dense (15-100% cover) mixedgrass herbaceous layer that grows 0.5-1 m tall. Other graminoids that co-occur and may achieve local dominance are Koeleria macrantha, Eleocharis palustris, and Poa spp. Many other species common in midgrass prairies and other grasslands are also found in this community, including Artemisia ludoviciana, Eriogonum spp., Bouteloua gracilis, and Hesperostipa comata. Shrubs and dwarf-shrubs are rare in this community, but occasional woody plants, such as Artemisia tridentata, Symphoricarpos spp., Ericameria nauseosa, or Krascheninnikovia lanata, may be present. Introduced species, such as Bromus tectorum, Bromus inermis, Poa pratensis, Melilotus spp. or Cirsium arvense, are common in some stands, especially where disturbed.

Diagnostic Characteristics: This association is characterized by an open to dense (15-100% cover) mixedgrass herbaceous layer that grows 0.5-1 m tall and is strongly dominated by Pascopyrum smithii.

Rationale for Nominal Species or Physiognomic Features: No Data Available

Classification Comments: This community is similar to several others that are dominated or codominated by Pascopyrum smithii. This association has been restricted to the Rocky Mountain foothills, meadows, and portions of the Intermountain West. Sites in the Great Plains dominated by Pascopyrum smithii are placed in other associations.

Similar NVC Types: No Data Available
note: No Data Available
Physiognomy and Structure: Perennial herbaceous graminoid growth from 0.5 to up to 1 m in height.

Floristics: This association is characterized by an open to dense (15-100% cover) mixedgrass herbaceous layer that grows 0.5-1 m tall and is strongly dominated by Pascopyrum smithii. Herbaceous cover may be significantly less on drier sites or after scarce cool-season precipitation. Other graminoids that co-occur and may achieve local dominance are Bouteloua gracilis, Distichlis spicata, Eleocharis palustris, Koeleria macrantha, and Sporobolus airoides. Many other species common in prairies and other grasslands are also found in this community, including Achnatherum lettermanii, Achillea millefolium, Artemisia frigida, Artemisia ludoviciana, Carex spp., Eriogonum spp., Hesperostipa comata (= Stipa comata), Juncus arcticus ssp. littoralis (= Juncus balticus), Lupinus argenteus, Pseudoroegneria spicata (= Elymus spicatus), Poa fendleriana, Poa secunda, and Solidago sp. Shrubs and dwarf-shrubs are rare in this community, but occasional woody plants, such as Artemisia arbuscula ssp. longiloba, Artemisia tridentata, Artemisia tridentata ssp. vaseyana, Atriplex canescens, Ericameria nauseosa, Krascheninnikovia lanata, Rhus trilobata, or Symphoricarpos spp., may be present. Introduced species, such as Agropyron cristatum, Cirsium arvense, Bromus arvensis (= Bromus japonicus), Bromus tectorum, Ceratocephala testiculata, Conyza canadensis, Iva axillaris, Lactuca serriola, Melilotus spp., Poa pratensis, Salsola kali, Sisymbrium altissimum, and Taraxacum officinale, are common in some stands, especially where disturbed.

Dynamics:  In semi-arid climates, this association is found in relatively mesic topographic positions such as swales, river terraces, floodplains and basins that may be temporarily or intermittently flooded, or in some classes, the fine-textured soil sometimes perches the water table (Hansen et al. 1995, Hall and Hansen 1997).
Environmental Description:  Elevation ranges from 600-3000 m. Stands occur on level to gently sloping terrain. They are found on alluvial fans, swales, river terraces, floodplains, valley bottoms and basins. The soils are typically deep (40-100 cm), slightly alkaline and well-developed with clay, clay loam, and silt loam textures, but also coarser textures such as sand and loamy sand. Some stands occur on perched water tables. Parent materials include Quaternary landslide deposits, volcanic rocks, sandstones and shale that have eroded and deposited as secondary stream alluvium.
Geographic Range: This midgrass prairie type is found in the central Rocky Mountains, ranging from Montana, Wyoming and Idaho and into Alberta, Canada.

Nations: CA,US

States/Provinces:  AB, ID, MT, WY


Confidence Level: Low - Poorly Documented

Confidence Level Comments: No Data Available
Grank: GNR

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.2 Saskatoon Serviceberry / Idaho Fescue - Bluebunch Wheatgrass Grassland & Shrubland Macrogroup M048 2.B.2.Nf.2
Group 2.B.2.Nf.2.c Rough Fescue - Idaho Fescue - Bluebunch Wheatgrass Central Rocky Mountain Foothill Grassland Group G273 2.B.2.Nf.2.c
Alliance A3988 Idaho Fescue - Bluebunch Wheatgrass - Western Wheatgrass Mesic Grassland Alliance A3988 2.B.2.Nf.2.c
Association CEGL005653 Western Wheatgrass Central Rocky Mountain Grassland CEGL005653 2.B.2.Nf.2.c
Concept Lineage: No Data Available

Predecessors: No Data Available

Obsolete Names: No Data Available

Obsolete Parents: No Data Available
Synonomy: = Agropyron smithii Habitat Type (Hall and Hansen 1997)
= Agropyron smithii Habitat Type (Hansen et al. 1995)
= Agropyron smithii Sodgrass Steppe (Thilenius et al. 1995) [a more playa-like wheatgrass type.]
= Brown''s Meadow Grassland (Christensen and Welsh 1963) [included in Wasatch Mountain meadow.]
= Western Wheatgrass (Elymus smithii) Dominance Type (Jones and Walford 1995)
= Western Wheatgrass Herbaceous Vegetation (Pascopyrum smithii Herbaceous Vegetation) (Bell et al. 2009)
= Wheat Grass Association (Ramaley 1919b)
= Wheatgrass (Aldous and Shantz 1924)
Concept Author(s): M.S. Reid

Author of Description: J. Drake, K.A. Schulz, J. Coles and G. Kittel

Acknowledgements: No Data Available

Version Date: 06-30-17
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