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A3221 Artemisia arbuscula ssp. longiloba Steppe & Shrubland Alliance

Type Concept Sentence: Artemisia arbuscula ssp. longiloba is dominant in the shrub canopy and is widespread in the Intermountain West, the southern Rocky Mountains, and in the western Great Plains.

Common (Translated Scientific) Name: Alkali Sagebrush Steppe & Shrubland Alliance

Colloquial Name: Alkali Sagebrush Steppe & Shrubland

Hierarchy Level:  Alliance

Type Concept: This shrub-herbaceous alliance occurs in the Intermountain West, into the southern Rocky Mountains and in the western Great Plains. The structure of these stands may be shrub-herbaceous or shrub-dominated. The shrub layer may be sparse to open and dominated by the low shrub Artemisia arbuscula ssp. longiloba. Shrub associates include Artemisia nova, Artemisia tridentata ssp. vaseyana, Artemisia tridentata ssp. wyomingensis, Artemisia tripartita, Chrysothamnus viscidiflorus, Gutierrezia sarothrae, and Purshia tridentata. Perennial grasses are dominant in the understory and may have sparse to very dense cover where they are more prominent than shrubs. Dominant to common grass species include Danthonia parryi, Elymus lanceolatus, Festuca idahoensis, Festuca thurberi, Pascopyrum smithii, Poa secunda, and Pseudoroegneria spicata. Other perennial grasses that may be present include Achnatherum hymenoides, Elymus elymoides, Hesperostipa comata, and Koeleria macrantha. Forb cover is typically minor. Stands occur on a variety of landforms, from flats and depressions to slopes and ridges. Soils are generally characterized by a heavy clay subsoil occurring within 25 cm of the soil surface, which restricts rooting depth. Soils are also alkaline and calcareous. Diagnostic of this alliance is a moderate (>20% cover) perennial graminoid layer with an Artemisia arbuscula ssp. longiloba-dominated low-shrub layer that has 10-40% cover. At least 40% of the total shrub cover is Artemisia arbuscula ssp. arbuscula.

Diagnostic Characteristics: Diagnostic of this alliance is the Artemisia arbuscula ssp. longiloba-dominated low-shrub layer (or codominated with >40% relative shrub cover of the nominal species).

Rationale for Nominal Species or Physiognomic Features: No Data Available

Classification Comments: Stands included in this alliance occur in environments (climate or substrates) that limit the growth of perennial graminoids or may be the result of heavy livestock grazing depleting the perennial graminoid layer of stands of shrub-herbaceous vegetation. The range of this association is currently restricted to Nevada. More survey and classification work are needed to fully describe the range of this alliance.

Similar NVC Types: No Data Available
note: No Data Available
Physiognomy and Structure: This alliance is characterized by a sparse to moderate microphyllous evergreen dwarf-shrub canopy (0.1-0.4 m in height). Cespitose graminoids dominate the understory with cover ranging from 10-70% and 0.3-1.0 m tall.

Floristics: The structure of these stands may be shrub-herbaceous or shrub-dominated. The shrub layer may be sparse to open (10-40% cover) and dominated by the low shrub Artemisia arbuscula ssp. longiloba. Shrub associates include Artemisia nova, Artemisia tridentata ssp. vaseyana, Artemisia tridentata ssp. wyomingensis, Artemisia tripartita, Chrysothamnus viscidiflorus, Gutierrezia sarothrae, and Purshia tridentata. Perennial grasses are dominant in the understory and may have sparse to very dense cover where they are more prominent than shrubs. Dominant to common grass species include Danthonia parryi, Elymus lanceolatus, Festuca idahoensis, Festuca thurberi, Pascopyrum smithii, Poa secunda, and Pseudoroegneria spicata. Other perennial grasses that may be present include Achnatherum hymenoides (= Oryzopsis hymenoides), Elymus elymoides, Hesperostipa comata (= Stipa comata), and Koeleria macrantha. Forb cover is typically minor.

Dynamics:  Due to the low-shrub stature of Artemisia arbuscula ssp. longiloba, this shrubland alliance is less susceptible to natural fire than taller Artemisia spp. shrublands. Grazing appears to have little effect on shrub densities, but tends to decrease the importance of tall bunch grasses and increase the cover of Arenaria congesta (Johnston 2001). Heavy livestock grazing may deplete the perennial graminoid layer and convert stands that are shrub-herbaceous in structure to those that are strictly shrub-dominated.
Environmental Description:  This shrub-herbaceous alliance occurs in the Intermountain West, into the southern Rocky Mountains and in the western Great Plains from 1600-3200 m (5500-10,600 feet) elevation. Stands occur on a variety of landforms, from flats and depressions to slopes and ridges. Soils are generally characterized by a heavy clay subsoil occurring within 25 cm of the soil surface, which restricts rooting depth. Soils are also alkaline and calcareous. Beetle and Johnson (1982) report that Artemisia arbuscula ssp. arbuscula grows in soils with a high volume of gravel (even though soil may be in clay textural class, or contain a clay-rich layer that impedes drainage), and that Artemisia arbuscula ssp. longiloba grows in clay soils, often alkaline, that contain no gravels.
Geographic Range: This alliance is widespread in the western United States, occurring from the Intermountain West, into the southern Rocky Mountains and the western Great Plains.

Nations: US

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


Confidence Level: Moderate

Confidence Level Comments: No Data Available
Grank: GNR

Greasons: No Data Available
Type Name Database Code Classification Code
Class 3 Desert & Semi-Desert Class C03 3
Subclass 3.B Cool Semi-Desert Scrub & Grassland Subclass S11 3.B
Formation 3.B.1 Cool Semi-Desert Scrub & Grassland Formation F033 3.B.1
Division 3.B.1.Ne Western North American Cool Semi-Desert Scrub & Grassland Division D040 3.B.1.Ne
Macrogroup 3.B.1.Ne.2 Little Sagebrush - Black Sagebrush - Scabland Sagebrush Steppe & Shrubland Macrogroup M170 3.B.1.Ne.2
Group 3.B.1.Ne.2.b Little Sagebrush - Bigelow''s Sagebrush - Black Sagebrush Steppe & Shrubland Group G308 3.B.1.Ne.2.b
Alliance A3221 Alkali Sagebrush Steppe & Shrubland Alliance A3221 3.B.1.Ne.2.b
Association CEGL001414 Alkali Sagebrush Shrubland CEGL001414 3.B.1.Ne.2.b
Association CEGL001415 Alkali Sagebrush / Western Wheatgrass Shrub Grassland CEGL001415 3.B.1.Ne.2.b
Association CEGL001416 Alkali Sagebrush / Bluebunch Wheatgrass Shrub Grassland CEGL001416 3.B.1.Ne.2.b
Association CEGL001522 Alkali Sagebrush / Idaho Fescue Shrub Grassland CEGL001522 3.B.1.Ne.2.b
Association CEGL001523 Alkali Sagebrush / Sandberg Bluegrass Shrub Grassland CEGL001523 3.B.1.Ne.2.b
Association CEGL002585 Alkali Sagebrush / Thick-spike Wheatgrass Shrubland CEGL002585 3.B.1.Ne.2.b
Association CEGL005996 Alkali Sagebrush / Cushion Plants Shrubland CEGL005996 3.B.1.Ne.2.b
Association CEGL005997 Alkali Sagebrush / Muttongrass Shrubland CEGL005997 3.B.1.Ne.2.b
Concept Lineage: This alliance is the combination of the former Artemisia arbuscula ssp. longiloba Shrubland (A.2549) and Artemisia arbuscula ssp. longiloba Shrub Herbaceous Alliances (A.2552).

Predecessors: No Data Available

Obsolete Names: No Data Available

Obsolete Parents: No Data Available
Synonomy: < SRM Cover Type #406 - Low Sagebrush (Shiflet 1994)
Concept Author(s): C. Jean, J. Kagan, P. Lyon, E. Peterson, K.A. Schulz, in Faber-Langendoen et al. (2013)

Author of Description: M.E. Hall

Acknowledgements: No Data Available

Version Date: 03-14-14
  • Beetle, A. A., and K. L. Johnson. 1982. Sagebrush in Wyoming. Wyoming Agricultural Experiment Station Bulletin 779. University of Wyoming, Laramie.
  • Faber-Langendoen, D., J. Drake, M. Hall, G. Kittel, S. Menard, C. Nordman, M. Pyne, M. Reid, M. Russo, K. Schulz, L. Sneddon, K. Snow, and J. Teague. 2013-2019b. Screening alliances for induction into the U.S. National Vegetation Classification: Part 1 - Alliance concept review. NatureServe, Arlington, VA.
  • Johnston, B. C. 2001. Ecological types of the Upper Gunnison Basin. Technical Report R2-RR-2001-01. USDA Forest Service, Rocky Mountain Region. Denver, CO.
  • Shiflet, T. N., editor. 1994. Rangeland cover types of the United States. Society for Range Management. Denver, CO. 152 pp.