Print Report

A4039 Pascopyrum smithii - Bouteloua gracilis Great Plains Grassland Alliance

Type Concept Sentence: This alliance is found in the southwestern Great Plains and into western New Mexico where Pascopyrum smithii and Bouteloua gracilis dominate in swales and valleys.

Common (Translated Scientific) Name: Western Wheatgrass - Blue Grama Great Plains Grassland Alliance

Colloquial Name: Great Plains Western Wheatgrass - Blue Grama Grassland

Hierarchy Level:  Alliance

Type Concept: This alliance of the southern Great Plains and western New Mexico mountains of the United States was once an extensive grassland. Ground cover is characterized by scattered bunchgrasses and patches of the rhizomatous grasses and litter with exposed soil and gravel in the intergrass spaces. Luxuriant cover that can be dominated by either Bouteloua gracilis or Pascopyrum smithii typifies this grassland. Graminoid diversity is usually low, with scattered grasses such as Elymus elymoides, Koeleria macrantha, and Muhlenbergia repens often present. In Kansas, Bouteloua curtipendula and Bouteloua dactyloides may also be present. The shrub layer is very open and moderate in diversity and generally includes Atriplex canescens and Krascheninnikovia lanata (which both occur as phases and can become dominant in disturbed areas), as well as Cylindropuntia imbricata and Opuntia phaeacantha. Forb diversity and cover are generally low. Stands occur within montane swales or along upland valley bottoms. It generally occurs on northerly or northeasterly aspects at elevations between 915 and 2440 m (3000-8000 feet). Slopes are typically gentle with fine-textured and well-developed soils that are predominantly from eroded Paleozoic sandstone and limestone.

Diagnostic Characteristics: This alliance is characterized by stands dominated by Pascopyrum smithii and Bouteloua gracilis.

Rationale for Nominal Species or Physiognomic Features: No Data Available

Classification Comments: This alliance currently contains only one association (CEGL001578). This alliance should be considered in relation to ~Pascopyrum smithii - Nassella viridula Northwestern Great Plains Grassland Alliance (A4031)$$. This alliance (A4039) has similar dominants, though it occurs further south than A4031. Current description is based strongly on New Mexico patterns, which may be sufficiently distinct from Great Plains to warrant further review. The limits of this type in western Oklahoma needs review.

Similar NVC Types: No Data Available
note: No Data Available
Physiognomy and Structure: This is an herbaceous alliance, dominated by short to mid-height graminoids. Mid grasses are the dominant vegetation in most examples of this alliance, although short grasses can be codominant. The vegetation tends to be denser where the mid grasses are predominant and more open where shorter graminoids are abundant. The mid grasses grow to 0.5-1.0 m on favorable sites, while the short grasses are less than 0.5 m tall. Both forb and shrub species are minor in this alliance. If shrubs are present, they are typically less than 1 m in height.

Floristics: Luxuriant cover that can be dominated by either Bouteloua gracilis or Pascopyrum smithii typifies this grassland. Graminoid diversity is usually low, with scattered grasses such as Elymus elymoides, Koeleria macrantha, and Muhlenbergia repens often present. In Kansas, Bouteloua curtipendula and Bouteloua dactyloides (= Buchloe dactyloides) may also be present. In the Texas panhandle, Buchloe dactyloides and Bouteloua curtipendula are common associates. Bouteloua spp disappear in wetter swales. The shrub layer is very open and moderate in diversity and generally includes Atriplex canescens and Krascheninnikovia lanata (which both occur as phases and can become dominant in disturbed areas), as well as Cylindropuntia imbricata (= Opuntia imbricata) and Opuntia phaeacantha. New Mexico stands contain a somewhat distinct set of associates. Forb diversity and cover are generally low. In New Mexico, forbs are common but variable; the most abundant are Artemisia campestris ssp. caudata, Engelmannia peristenia, Glandularia bipinnatifida, and Penstemon virgatus. Juniperus monosperma or Pinus edulis communities usually surround this swale association the mountains of New Mexico. In New Mexico, Atriplex canescens is the most frequently occurring and abundant shrub, with Ericameria nauseosa, Opuntia phaeacantha, and Gutierrezia sarothrae common associates, but overall cover seldom exceeds 2.5%.

Dynamics:  Pascopyrum smithii is rhizomatous and is tolerant of moderate grazing. If severely overgrazed, Pascopyrum smithii will decline and may be replaced by less desirable warm-season grasses and exotic species such as Poa pratensis.
Environmental Description:  Stands occur along upland valley bottoms, or in New Mexico, within montane swales, where it generally occurs on northerly or northeasterly aspects at elevations between 915 and 2500 m (3000-8000 feet). Slopes are typically gentle with fine-textured and well-developed soils that are predominantly from eroded Paleozoic sandstone and limestone. In Kansas, stands are common on nearly level uplands or shallow depressions in uplands. Soils are silty clay loam with an impermeable or slowly permeable claypan subsoil layer. Ground cover is characterized by scattered bunchgrasses and patches of the rhizomatous grasses and litter with exposed soil and gravel in the intergrass spaces.
Geographic Range: This alliance is found in the southern Great Plains, of the United States, ranging from Colorado and Kansas south to Texas. It occurs in the Oklahoma panhandle, Southeast Colorado and northeast New Mexico.

Nations: CA,US

States/Provinces:  CO, KS, NM, OK, TX


Confidence Level: Moderate

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.Nb Central North American Grassland & Shrubland Division D023 2.B.2.Nb
Macrogroup 2.B.2.Nb.2 Needle-and-Thread - Western Wheatgrass - Plains Rough Fescue Grassland Macrogroup M051 2.B.2.Nb.2
Group 2.B.2.Nb.2.a Little Bluestem - Sideoats Grama - Western Wheatgrass Mixedgrass Prairie Group G133 2.B.2.Nb.2.a
Alliance A4039 Western Wheatgrass - Blue Grama Great Plains Grassland Alliance A4039 2.B.2.Nb.2.a
Association CEGL001578 Western Wheatgrass - Blue Grama Grassland CEGL001578 2.B.2.Nb.2.a
Association CEGL001702 Needle-and-Thread Colorado Front Range Grassland CEGL001702 2.B.2.Nb.2.a
Concept Lineage: This alliance contains one association from old A.1232.

Predecessors: No Data Available

Obsolete Names: No Data Available

Obsolete Parents: No Data Available
Synonomy: No Data Available
Concept Author(s): J. Drake, in Faber-Langendoen et al. (2013)

Author of Description: J. Drake, D. Faber-Langendoen

Acknowledgements: No Data Available

Version Date: 12-18-14
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