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Montana Field Guide

Montana Field Guides

Big Sagebrush Steppe

Provisional State Rank: S5

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General Description

This widespread ecological system occurs throughout much of central Montana, and north and east onto the western fringe of the Great Plains. In central Montana, where this system occurs on both glaciated and non-glaciated landscapes, it differs slightly, with more summer rain than winter precipitation and more precipitation annually. Throughout its distribution, soils are typically deep and non-saline, often with a microphytic crust. Overall shrub cover may be as low as 10 percent, or as high as 25%, but this system is always dominated by perennial grasses and forbs with greater than 25% cover. In Montana and Wyoming, stands are more mesic, with more biomass of grass, and have less shrub diversity than stands farther to the west, and 50 to 90% of the occurrences are dominated by Wyoming big sagebrush with western wheatgrass (Pascopyrum smithii). Japanese brome (Bromus japonicus) and cheatgrass (Bromus tectorum) are indicators of disturbance, but cheatgrass is typically not as abundant as in the Intermountain West, possibly due to a colder climate. The natural fire regime of this ecological system maintains a patchy distribution of shrubs, preserving the steppe character. Shrubs may increase following heavy grazing and/or with fire suppression. In central and eastern Montana, complexes of prairie dog towns are common in this ecological system.

Diagnostic Characteristics

Lowland elevations, deep, aridic soils, xeromorphic shrubs, bunchgrasses, shrub cover less than 10%, Artemsisia tridentata ssp. wyomingensis, Artemsisia tridentata ssp. tridentata

Similar Systems

This system occurs throughout central and southeastern Montana, usually at elevations between 1,500 and 2,300 meters (4,921-7,546 feet). It also occurs throughout much of the Columbia Plateau and northern Great Basin, east into the Wyoming Basins, and north and east onto the western fringe of the Great Plains in Montana and South Dakota.

Ecological System Distribution
Approximately 43,271 square kilometers are classified as Big Sagebrush Steppe in the 2017 Montana Land Cover layers.  Grid on map is based on USGS 7.5 minute quadrangle map boundaries.

Montana Counties of Occurrence
Beaverhead, Big Horn, Blaine, Broadwater, Carbon, Carter, Cascade, Chouteau, Custer, Dawson, Deer Lodge, Fallon, Fergus, Flathead, Gallatin, Garfield, Glacier, Golden Valley, Hill, Jefferson, Judith Basin, Lewis and Clark, Liberty, Lincoln, Madison, Mccone, Meagher, Mineral, Missoula, Musselshell, Park, Petroleum, Phillips, Pondera, Powder River, Powell, Prairie, Ravalli, Richland, Roosevelt, Rosebud, Sanders, Silver Bow, Stillwater, Sweet Grass, Teton, Toole, Treasure, Valley, Wheatland, Wibaux, Yellowstone

Spatial Pattern
Large patch

This system occurs as extensive matrix types on level to gently rolling plains, plateaus, sideslopes and toeslopes, and as small and large patches in dissected landscapes such as breaks and badlands. Soils are alkaline and are developed from various parent materials that have weathered to predominantly heavy-textured, clay-rich Aridisols, and in more mesic conditions, Mollisols. In central Montana, this system differs slightly, with more summer rain than winter precipitation, more precipitation annually, and it occurs on glaciated and non-glaciated landscapes. Across the Montana distribution, soils are typically deep and non-saline, often with a microphytic crust. In southeastern Montana, these sites are associated with heavy soils. In north-central Montana, soils tend to be shallower often with gravelly or claypan surfaces.


In Montana, this system is dominated by Wyoming big sagebrush (Artemisia tridentata ssp. wyomingensis). Other shrubs present may include basin big sagebrush (Artemisia tridentata ssp. tridentata), silver sagebrush (Artemisia cana), greasewood (Sarcobatus vermiculatus), saltbush (Atriplex species), rubber rabbitbrush (Ericameria nauseosa), green rabbitbrush (Chrysothamnus viscidiflorus), and antelope bitterbrush (Purshia tridentata). Overall shrub cover is less than 10 percent.

Perennial herbaceous components typically contribute greater than 25% vegetative cover and consist mostly of rhizomatous and bunch-form graminoids, with a diversity of perennial forbs. In Montana, the dominant graminoid in this system is western wheatgrass (Pascopyrum smithii). Other species include Indian ricegrass (Achnatherum hymenoides), blue grama (Bouteloua gracilis),Sandberg’s bluegrass (Poa secunda), or bluebunch wheatgrass (Pseudoroegneria spicata). Dryland rhizomatous sedges such as threadleaf sedge (Carex filifolia) and needleleaf sedge (Carex duriuscula) are very common and important in the eastern distribution of this system in Montana and Wyoming.

Common forbs include Hood’s phlox (Phlox hoodii), sandwort (Arenaria species), prickly pear (Opuntia species), scarlet globemallow (Sphaeralcea coccinea), purple prairie clover (Dalea purpurea), gayfeather (Liatris punctata), and milkvetch (Astragalus species). Within this system, cheatgrass (Bromus tectorum), Japanese brome (Bromus japonicus) and other invasive weeds can be abundant where there is frequent disturbance.

National Vegetation Classification Switch to Full NVC View

Adapted from US National Vegetation Classification

A1528 Artemisia tripartita ssp. tripartita - Artemisia tridentata Mesic Steppe & Shrubland Alliance
CEGL001536 Artemisia tripartita ssp. tripartita - Festuca idahoensis Shrub Grassland
CEGL001537 Artemisia tripartita ssp. tripartita - Festuca campestris Shrub Grassland
CEGL001538 Artemisia tripartita ssp. tripartita - Pseudoroegneria spicata Shrub Grassland
A3179 Purshia tridentata - Artemisia tridentata Mesic Steppe & Shrubland Alliance
CEGL001494 Purshia tridentata - Festuca campestris Shrub Grassland
CEGL001495 Purshia tridentata - Pseudoroegneria spicata Shrub Grassland
CEGL001498 Purshia tridentata - Hesperostipa comata Shrub Grassland
CEGL002674 Purshia tridentata - Festuca idahoensis Shrub Grassland
A3182 Artemisia tridentata ssp. Wyomingensis Mesic Steppe & Shrubland Alliance
CEGL001047 Artemisia tridentata ssp. wyomingensis - Pascopyrum smithii Shrub Grassland
CEGL001535 Artemisia tridentata ssp. wyomingensis - Pseudoroegneria spicata Shrub Grassland
A3183 Artemisia tridentata ssp. tridentata - Artemisia tridentata ssp. Xericensis Mesic Steppe & Shrubland Alliance
CEGL001014 Artemisia tridentata ssp. tridentata - Festuca idahoensis Shrubland
CEGL001016 Artemisia tridentata ssp. tridentata - Leymus cinereus Shrubland
CEGL001017 Artemisia tridentata ssp. tridentata - Pascopyrum smithii / (Elymus lanceolatus) Shrubland
CEGL001018 Artemisia tridentata (ssp. tridentata, ssp. xericensis) - Pseudoroegneria spicata Shrub Grassland
CEGL001530 Artemisia tridentata - Festuca idahoensis Shrub Grassland
CEGL002966 Artemisia tridentata ssp. tridentata - Hesperostipa comata Shrubland
A3184 Artemisia tridentata ssp. Wyomingensis Dry Steppe & Shrubland Alliance
A3198 Artemisia tridentata - Mixed Shrub Dry Steppe & Shrubland Alliance
A3586 Artemisia cana ssp. Cana Wet Shrubland Alliance
CEGL001556 Artemisia cana ssp. cana - Pascopyrum smithii Shrub Wet Meadow
*Disclaimer: Alliances and Associations have not yet been finalized in the National Vegetation Classification (NVC) standard.  A complete version of the NVC for Montana can be found here.

Dynamic Processes

The natural fire regime of this ecological system maintains a patchy distribution of shrubs, so the general aspect of the vegetation is steppe grassland. Shrubs may increase following heavy grazing and/or with fire suppression. Response to grazing can be variable, depending on the type of grazer and the season in which grazing occurs. Needle and thread (Hesperostipa comata) can increase in abundance in response to either grazing or fire. Microphytic crust is very important in this ecological system and is easily damaged under all grazing regimes.In central and eastern, complexes of prairie dog towns are common in this ecological system, and can be a significant disturbance.

Big sagebrush is easily killed by fire at all intensities, and when exposed to fire, plants do not resprout (Wright et al. 1979). In southwestern Montana, Wambolt and others (2001) found that fire in big sagebrush is stand replacing, killing or removing most of the aboveground vegetation, and that recovery to pre-burn cover (of sagebrush) takes at least 20 years. In Montana, Wyoming big sagebrush may require a century or longer to recover from fire (Lesica et al. 2005).

Heavy grazing practices can also lead to a decrease in associated grasses and an increase in the spread of annual bromes. Sites infested with annual bromes are changing the dynamics of this system by increasing fire potential, severity and spread.

In the absence of natural fire, periodic low intensity prescribed burns can be used to maintain and restore this system to similar pre-settlement conditions. Low intensity prescribed fire is used to reduce sagebrush cover; in order to increase herbaceous forage and improve habitat quality for sage grouse and other wildlife by creating a mosaic of burned and unburned patches. Excessive grazing can result in the demise of the most common perennial grasses in this system and lead to an abundance cheatgrass or Japanese brome.

Restoration Considerations

Successful restoration of native grasses within this system may be limited to sites where pre-fire cheatgrass cover was low. Fall germination and rapid elongation of roots provide cheatgrass with a competitive advantage over native perennial species (Harris 1967). In trials, cheatgrass reduced growth of bluebunch wheatgrassseedlings and was capable of producing twice the root quantity of bluebunch wheatgrass during the first 45 days of growth (Aguirre and Johnson, 1991). Prolific seed production also contributes to the competitive advantage of this species over native grasses. However, some selections of bluebunch wheatgrass exhibit desirable growth characteristics that hold promise for establishing this species on cheatgrass-infested sites.

Severely burned sites may require replanting with mountain big sagebrush seedlings due to slow recovery time and low rates of natural seedling recruitment. Generally, larger container volume of nursery stock results in higher outplanting success; 10 to 20 cubic inch container stock is recommended.

Wyoming big sagebrushhas been shown to have subspecies and ecotypes that are morphologically and ecologically distinct. Collecting seeds from the appropriate subspecies in the proposed out-planting site is recommended (Mahalovich and McArthur, 2004). The geographic ranges of each subspecies should serve as the geographic boundary for each seed collection zone, with the additional restriction that seeds and plants should not be moved further than 483 kilometers (300 mi) to a target planting site, or outside their native distribution. These seed transfer guidelines are an indication of the habitat requirements of the subspecies.

Polyploidy is also an important factor in adaptation. Polyploidy can influence plant fertility and vigor, and polyploidy patterns are evident at the ecotonal interfaces and within populations. Polyploids are better adapted to extreme ecological environments than diploids (Sanderson et al, 1989; McArthur and Sanderson, 1999). Thus, specific ecotypes or ploidy level of Wyoming big sagebrush may also be useful for selecting seed sources for outplanting, especially on droughty or mineral soils (Mahalovich and McArthur, 2004).

Species Associated with this Ecological System
  • Details on Creation and Suggested Uses and Limitations
    How Associations Were Made
    We associated the use and habitat quality (common or occasional) of each of the 82 ecological systems mapped in Montana for vertebrate animal species that regularly breed, overwinter, or migrate through the state by:
    1. Using personal observations and reviewing literature that summarize the breeding, overwintering, or migratory habitat requirements of each species (Dobkin 1992, Hart et al. 1998, Hutto and Young 1999, Maxell 2000, Foresman 2012, Adams 2003, and Werner et al. 2004);
    2. Evaluating structural characteristics and distribution of each ecological system relative to the species' range and habitat requirements;
    3. Examining the observation records for each species in the state-wide point observation database associated with each ecological system;
    4. Calculating the percentage of observations associated with each ecological system relative to the percent of Montana covered by each ecological system to get a measure of "observations versus availability of habitat".
    Species that breed in Montana were only evaluated for breeding habitat use, species that only overwinter in Montana were only evaluated for overwintering habitat use, and species that only migrate through Montana were only evaluated for migratory habitat use.  In general, species were listed as associated with an ecological system if structural characteristics of used habitat documented in the literature were present in the ecological system or large numbers of point observations were associated with the ecological system.  However, species were not listed as associated with an ecological system if there was no support in the literature for use of structural characteristics in an ecological system, even if point observations were associated with that system.  Common versus occasional association with an ecological system was assigned based on the degree to which the structural characteristics of an ecological system matched the preferred structural habitat characteristics for each species as represented in scientific literature.  The percentage of observations associated with each ecological system relative to the percent of Montana covered by each ecological system was also used to guide assignment of common versus occasional association.  If you have any questions or comments on species associations with ecological systems, please contact the Montana Natural Heritage Program's Senior Zoologist.

    Suggested Uses and Limitations
    Species associations with ecological systems should be used to generate potential lists of species that may occupy broader landscapes for the purposes of landscape-level planning.  These potential lists of species should not be used in place of documented occurrences of species (this information can be requested at: or systematic surveys for species and evaluations of habitat at a local site level by trained biologists.  Users of this information should be aware that the land cover data used to generate species associations is based on imagery from the late 1990s and early 2000s and was only intended to be used at broader landscape scales.  Land cover mapping accuracy is particularly problematic when the systems occur as small patches or where the land cover types have been altered over the past decade.  Thus, particular caution should be used when using the associations in assessments of smaller areas (e.g., evaluations of public land survey sections).  Finally, although a species may be associated with a particular ecological system within its known geographic range, portions of that ecological system may occur outside of the species' known geographic range.

    Literature Cited
    • Adams, R.A.  2003.  Bats of the Rocky Mountain West; natural history, ecology, and conservation.  Boulder, CO: University Press of Colorado.  289 p.
    • Dobkin, D. S.  1992.  Neotropical migrant land birds in the Northern Rockies and Great Plains. USDA Forest Service, Northern Region. Publication No. R1-93-34.  Missoula, MT.
    • Foresman, K.R.  2012.  Mammals of Montana.  Second edition.  Mountain Press Publishing, Missoula, Montana.  429 pp.
    • Hart, M.M., W.A. Williams, P.C. Thornton, K.P. McLaughlin, C.M. Tobalske, B.A. Maxell, D.P. Hendricks, C.R. Peterson, and R.L. Redmond. 1998.  Montana atlas of terrestrial vertebrates.  Montana Cooperative Wildlife Research Unit, University of Montana, Missoula, MT.  1302 p.
    • Hutto, R.L. and J.S. Young.  1999.  Habitat relationships of landbirds in the Northern Region, USDA Forest Service, Rocky Mountain Research Station RMRS-GTR-32.  72 p.
    • Maxell, B.A.  2000.  Management of Montana's amphibians: a review of factors that may present a risk to population viability and accounts on the identification, distribution, taxonomy, habitat use, natural history, and the status and conservation of individual species.  Report to U.S. Forest Service Region 1.  Missoula, MT: Wildlife Biology Program, University of Montana.  161 p.
    • Werner, J.K., B.A. Maxell, P. Hendricks, and D. Flath.  2004.  Amphibians and reptiles of Montana.  Missoula, MT: Mountain Press Publishing Company. 262 p.

Original Concept Authors
Natureserve Western Ecology Group

Montana Version Authors
L.K. Vance, T. Luna, S.V. Cooper

Version Date

  • Classification and Map Identifiers

    Cowardin Wetland Classification: Not applicable

    NatureServe Identifiers:
    Element Global ID 28616
    System Code CES304.778, Inter-Mountain Basins Big Sagebrush Steppe

    5454: Inter-Mountain Basins Big Sagebrush Steppe

  • Additional ReferencesLegend:   View Online Publication
    Do you know of a citation we're missing?
    • Aguirre, Lucrecia, and Douglas A. Johnson. 1991. "Influence of Temperature and Cheatgrass Competition on Seedling Development of Two Bunchgrasses". Journal of Range Management. 44 (4): 347-354.
    • Harris, G.A. 1967. Some competitive relationships between Agropyron spicatum and Bromus tectorum. Ecological Monographs 37:89-111.
    • Lesica, P., S.V. Cooper, and G.M. Kudray. 2005. Big sagebrush shrub-steppe postfire succession in southwest Montana. Prepared for U.S. Department of the Interior, Bureau of Land Management, Dillon Field Office. Montana Natural Heritage Program, Helena, MT. 29 pp. plus appendices.
    • Mahalovich, Mary F., and E. Durant McArthur. 2005. "Sagebrush (Artemisia spp.) Seed and Plant Transfer Guidelines". Native Plants Journal. 5 (2): 141-148.
    • McArthur, E. Durant, and Stewart C. Sanderson. 1999. "Cytogeography and Chromosome Evolution of Subgenus Tridentatae of Artemisia (Asteraceae)". American Journal of Botany. 86 (12): 1754-1775.
    • Mueggler, W. F. and W. L. Stewart. 1980. Grassland and shrubland habitat types of western Montana. USDA Forest Service Gen. Tech. Rep. INT-66, Intermountain Forest and Range Exp. Sta., Ogden, Utah. 154 pp.
    • Sanderson SC, McArthur ED, Stutz HC. 1989. A relationship between polyploidy level and habitat in western shrub species. In: Wallace A, McArthur ED, Haferkamp MR, editors. Proceedings: symposium on shrub ecophysiology and biotechnology.1987. June 30-July 2; Logan, UT. Ogden, UT: U.S. Department of Agriculture. Forest Service. Intermountain Research Station; p 23-30.
    • Wambolt, C. L., K. S. Walhof and M. R. Frisina. 2001. Recovery of big sagebrush communities after burning in southwestern Montana. Journal of Environmental Management 61: 243-252.
    • Wright, H. A., L. F. Neuenschwander, and C. M. Britton. 1979. The role and use of fire in sagebrush-grass and pinyon-juniper plant communities: A state of the art review. USDA Forest Service General Technical Report INT-58. Intermountain Forest and Range Experiment Station. Ogden, UT.

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Citation for data on this website:
Big Sagebrush Steppe — Inter-Mountain Basins Big Sagebrush Steppe.  Montana Field Guide.  Retrieved on , from