Print Report
A4032 Pseudoroegneria spicata - Pascopyrum smithii - Hesperostipa comata Grassland Alliance
Type Concept Sentence: This alliance is found in the northwestern Great Plains on shallow, rocky soils where Pseudoroegneria spicata is consistently abundant to dominant.
Common (Translated Scientific) Name: Bluebunch Wheatgrass - Western Wheatgrass - Needle-and-Thread Grassland Alliance
Colloquial Name: Northwestern Great Plains Bluebunch Wheatgrass - Western Wheatgrass Grassland
Hierarchy Level: Alliance
Type Concept: This alliance is found in the northwestern Great Plains. Short and medium-tall graminoids dominate and total vegetation cover is low to moderate. Pseudoroegneria spicata is consistently abundant to dominant. Other species that can be common or dominant on some sites are Pascopyrum smithii, Elymus lanceolatus, Hesperostipa comata, and Bouteloua gracilis. Associated species include Schizachyrium scoparium, Carex duriuscula, Bouteloua curtipendula, Koeleria macrantha, and Poa secunda. The alliance occurs on moderate to steep slopes. Soils tend to be shallow and with coarse rock fragments, but the alliance can be on deeper soils, too.
Diagnostic Characteristics: This northwestern Great Plains mixedgrass alliance is dominated by Pseudoroegneria spicata, sometimes in conjunction with Bouteloua gracilis, Pascopyrum smithii, or Hesperostipa comata.
Rationale for Nominal Species or Physiognomic Features: No Data Available
Classification Comments: No Data Available
Similar NVC Types: No Data Available
note: No Data Available
Physiognomy and Structure: This alliance is has a sparse to moderate cover of perennial bunchgrasses and shortgrasses. There is also a sparse to moderate cover of perennial forbs. Sparse scattered shrubs and dwarf-shrubs are often present.
Floristics: Stands are characterized by a sparse to moderate herbaceous layer that is codominated by the cool-season, medium-tall bunchgrass Pseudoroegneria spicata and the warm-season shortgrass Bouteloua gracilis. The dwarf-shrub Artemisia frigida is often present. Other characteristic species may include Heterotheca villosa, Koeleria macrantha, Opuntia polyacantha, Phlox hoodii, Poa secunda, and Sphaeralcea coccinea. Stands in Montana may be codominated by Hesperostipa comata (= Stipa comata). Other species common in the north are Liatris punctata, Ericameria nauseosa (= Chrysothamnus nauseosus), Calamagrostis montanensis, Carex duriuscula (= Carex stenophylla), and Carex filifolia. In Colorado, Achnatherum hymenoides (= Oryzopsis hymenoides), Penstemon caespitosus, Erigeron engelmannii, Artemisia tridentata ssp. wyomingensis, Ericameria parryi (= Chrysothamnus parryi), and Achnatherum pinetorum (= Stipa pinetorum) are also common.
Dynamics: Pseudoroegneria spicata is a cool-season midgrass that begins growth in the spring and continues until the soils dry out midsummer and it goes dormant. It may regrow with fall moisture. This grass tolerates dormant-period grazing well but is sensitive to defoliation during the growing season. Light spring use or fall grazing can help retain plant vigor (Comer et al. 1999). Bouteloua gracilis is a grazing-tolerant, warm-season shortgrass that is dormant during spring and does not begin growth until summer. Year-long and spring grazing favor Bouteloua gracilis and may convert these stands to shortgrass steppe. Both species usually survive fire, especially if fire occurs during dormancy (FEIS 1998).
Environmental Description: Grasslands included in this alliance occur on steeper slopes in the western Great Plains and on toeslopes in the foothills on the east side of the Continental Divide in Montana. It is also reported from windswept ridges in North Park and Middle Park in north-central Colorado. Elevations are usually below 1800 m in Montana and between 2250-2700 m in Colorado. Climate is temperate. Mean annual precipitation ranges from 25-46 cm, but the evapotranspiration rate is high. Sites are relatively dry on moderate to steep slopes with southerly to westerly exposures. Soils are typically moderately deep but are shallower in Colorado stands. They are lithic, often calcareous, gravelly loams and clay loams with pH of 7-8. Soils may be derived from a variety of parent materials that may include granite, gneiss, quartz monzonite, granodiorite, sandstone, limestone, shale, bentonite clay, volcanic ash and tuff. Surface rock ranges from 1-46% and bare ground from 1-42%. Lichens are important is some stands. Adjacent vegetation includes shrublands dominated by Artemisia arbuscula ssp. longiloba or Artemisia tridentata, and grassland dominated by Hesperostipa comata or Bouteloua gracilis.
Geographic Range: This alliance is found in the northwestern Great Plains in eastern Montana, Wyoming and in western North Dakota.
Nations: US
States/Provinces: MT, ND, WY
Plot Analysis Summary:
http://vegbank.org/natureserve/ELEMENT_GLOBAL.2.900083
Confidence Level: Low
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.b Needle-and-Thread - Blue Grama Dry Mixedgrass Prairie Group | G331 | 2.B.2.Nb.2.b |
| Alliance | A4032 Bluebunch Wheatgrass - Western Wheatgrass - Needle-and-Thread Grassland Alliance | A4032 | 2.B.2.Nb.2.b |
| Association | CEGL001663 Bluebunch Wheatgrass - Sideoats Grama Grassland | CEGL001663 | 2.B.2.Nb.2.b |
| Association | CEGL001664 Bluebunch Wheatgrass - Blue Grama Grassland | CEGL001664 | 2.B.2.Nb.2.b |
| Association | CEGL001675 Bluebunch Wheatgrass - Western Wheatgrass Grassland | CEGL001675 | 2.B.2.Nb.2.b |
Concept Lineage: This alliance is composed of two associations from old A.1265 and one from old A.1239.
Predecessors: No Data Available
Obsolete Names: No Data Available
Obsolete Parents: No Data Available
Synonomy: ? Agropyron spicatum/Bouteloua gracilis Habitat Type (Mueggler and Stewart 1980)
>< Agropyron spicatum Series (Johnson and Simon 1987)
? Roegneria spicata Series (Johnston 1987) [includes eleven Festuca idahoensis dominated plant associations.]
? North Park Resource Type (Terwilliger and Smith 1978)
>< Agropyron spicatum Series (Johnson and Simon 1987)
? Roegneria spicata Series (Johnston 1987) [includes eleven Festuca idahoensis dominated plant associations.]
? North Park Resource Type (Terwilliger and Smith 1978)
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