Print Report

A3985 Elymus lanceolatus - Hesperostipa comata - Phacelia hastata Central Rocky Mountain Sand Deposit Grassland Alliance

Type Concept Sentence: This alliance is characterized by a sparse to moderately dense herbaceous layer dominated by the medium-tall perennial graminoid Elymus lanceolatus with Hesperostipa comata or Phacelia hastata present to codominant and occurs in the Centennial Valley Sandhills in southwestern Montana, a high and cold valley on open, sandy flats in the Columbia River plains.

Common (Translated Scientific) Name: Streambank Wheatgrass - Needle-and-Thread - Silverleaf Scorpionweed Central Rocky Mountain Sand Deposit Grassland Alliance

Colloquial Name: Central Rocky Mountain Sand Deposit Grassland

Hierarchy Level:  Alliance

Type Concept: The vegetation of this grassland alliance is characterized by a sparse to moderately dense herbaceous layer dominated by the medium-tall perennial graminoid Elymus lanceolatus with Hesperostipa comata or Phacelia hastata present to codominant. Elymus lanceolatus binds the loose sand providing 5-25% cover. Other associated species include shrubs such as Ericameria nauseosa, Tetradymia canescens, grasses Achnatherum hymenoides, Poa secunda, and forbs Astragalus sclerocarpus, Eriogonum ovalifolium var. purpureum, Linum perenne, Oenothera pallida, Phlox longifolia, and Psoralidium tenuiflorum. Non-native species include Bromus tectorum, Centaurea diffusa, Sisymbrium altissimum, and Salsola kali. This alliance occurs in the Centennial Valley Sandhills in southwestern Montana and sandy plains along the Columbia River. Stands found in a high and cold Centennial Valley are at 2000-2135 m elevation and occur in a mosaic with active sand dunes and dune shrublands with occurrences less than one acre in size. Along the Columbia River, stands range from 300-765 m elevation. Sites are level to moderately sloping sandy plains and low dunes. Soils are deep loess or sand. Disturbance is important to the maintenance of these seral communities, and it is associated with recent blowouts.

Diagnostic Characteristics: This sand deposit grassland alliance is characterized by a sparse to moderately dense herbaceous layer dominated by the medium-tall diagnostic perennial graminoid Elymus lanceolatus often with Hesperostipa comata or Phacelia hastata present to codominant. Associated species include shrubs such as Ericameria nauseosa, Tetradymia canescens, grasses Achnatherum hymenoides, Poa secunda, and forbs Astragalus sclerocarpus, Eriogonum ovalifolium var. purpureum, Linum perenne, Oenothera pallida, Phlox longifolia, and Psoralidium tenuiflorum.

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: Vegetation included in this alliance has a sparse to moderately dense herbaceous layer dominated by medium-tall perennial grasses with perennial forbs. Scattered evergreen and deciduous shrubs may be present. Annual forbs and grasses are common in some stands.

Floristics: These sparse grasslands have been described from the Columbia River plains and the sandhills in the Centennial Valley in southwestern Montana. The cool-season perennial grass Elymus lanceolatus is usually the dominant species. It is a rhizomatous perennial grass that binds the loose sand providing 5-25% cover or higher. The bunchgrass Hesperostipa comata (= Stipa comata) and the perennial forb Phacelia hastata are codominant in some stands. Other species that may be present with sparse cover include grasses, such as Achnatherum hymenoides (= Oryzopsis hymenoides), Poa secunda, and forbs such as Achillea millefolium, Astragalus sclerocarpus, Eriogonum ovalifolium, Linum perenne, Oenothera pallida, Phlox longifolia, and Psoralidium tenuiflorum (= Psoralea tenuiflora). Very scattered patches of 1- to 2-m tall shrubs occasionally occur, including evergreen and deciduous species such as Artemisia tridentata, Ericameria nauseosa (= Chrysothamnus nauseosus), Purshia tridentata, and Tetradymia canescens. Non-native species are common especially in the Columbia Basin stands and include Bromus tectorum, Centaurea diffusa, Salsola kali, and Sisymbrium altissimum. Diagnostic of this alliance is the dominance of Elymus lanceolatus with Hesperostipa comata and Phacelia hastata in the herbaceous layer.

Dynamics:  This seral vegetation is scattered across open sandy areas where disturbance has created habitat for the strongly rhizomatous Elymus lanceolatus ssp. lanceolatus to colonize the open sandy area and stabilize the sand, providing 10-15% cover. In stands in Montana, regular fires, grazing and small mammal digging initiate the blowouts that provide the disturbance that maintains this vegetation and the habitat for a number of sensitive species. Were one to suppress fire and remove cattle over this landscape, succession would lead to stable Artemisia tridentata ssp. vaseyana- and Artemisia tripartita-dominated communities and the probable loss of the sensitive species.
Environmental Description:  This vegetation occurs as an open, sandy grassland on flat Columbia River plains and in the Centennial Valley Sandhills, a high and cold valley in southwestern Montana. The climate is semi-arid, with average annual precipitation varying across this region from 20-40 cm. Summers are typically hot and dry. Winters are moderately cold, with most precipitation falling during October through May. Stands along the Columbia River occur from 300-765 m elevations on topography composed of very low (0.5 m) dunes. Open sand comprises almost 50-90% of the cover. Sites are flat to gentle slopes with dry, deep loess or sandy soils. It often is found in a patchwork with sand dunes and dune shrublands. In southwestern Montana, elevations range from approximately 2050-2500 m. Stands are patchily distributed in the sandhills area with occurrences less than one acre in size. Sites are level to moderately sloping sandy plains and dunes. Disturbance is important to the maintenance of these seral communities, and it is associated with recent blowouts. Adjacent vegetation includes shrublands dominated by Artemisia tridentata and Artemisia tripartita.
Geographic Range: This alliance occurs in the Centennial Valley Sandhills in southwestern Montana, a high and cold valley and on open, sandy flats in the Columbia River and Snake River plains in Oregon, Washington and Idaho. It is also reported from Utah and Wyoming.

Nations: US

States/Provinces:  CO, ID, MT, OR, UT, WA, WY


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.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 A3985 Streambank Wheatgrass - Needle-and-Thread - Silverleaf Scorpionweed Central Rocky Mountain Sand Deposit Grassland Alliance A3985 2.B.2.Nf.2.c
Association CEGL001745 Thick-spike Wheatgrass - Silverleaf Phacelia Grassland CEGL001745 2.B.2.Nf.2.c
Association CEGL001746 Thick-spike Wheatgrass - Needle-and-Thread Grassland CEGL001746 2.B.2.Nf.2.c
Association CEGL005595 Thick-spike Wheatgrass - Silvery Lupine Grassland CEGL005595 2.B.2.Nf.2.c
Concept Lineage: This new alliance includes associations from Old Alliance V.A.5.N.c. Elymus lanceolatus Herbaceous Alliance (A.1242).

Predecessors: No Data Available

Obsolete Names: No Data Available

Obsolete Parents: No Data Available
Synonomy: No Data Available
Concept Author(s): K.A. Schulz, in Faber-Langendoen et al. (2014)

Author of Description: K.A. Schulz

Acknowledgements: No Data Available

Version Date: 09-29-16
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