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Montana Field Guide

Montana Field Guides

Big Sagebrush Shrubland

Provisional State Rank: S3
(see reason below)

External Links

State Rank Reason
The range of this system includes areas where there may be extensive oil and gas development. Annual bromes are also increasing the risk of catastrophic fire.

General Description

This system is similar to Inter-Mountain Basins Big Sagebrush Steppe, but is characterized by lower herbaceous cover, usually less than 25 percent. In Montana, it occurs as a result of historic and current overgrazing practices and can be considered a disclimax expression of sagebrush steppe. It occurs in broad basins between mountain ranges, on plains and on foothills between 670 and 1,066 meters (2,200-3,500 feet). It can occur on all aspects. Soils are usually fine to coarse textured, well-drained and non-saline. In Montana, these shrublands are dominated by Wyoming big sagebrush (Artemisia tridentata ssp. wyomingensis) and, to a lesser extent, basin big sagebrush (Artemisia tridentata ssp. tridentata). On pristine sites, the shrub layer ranges from 1.2-3.6 meters (4-12 feet). Other shrubs may be present on some occurrences, e.g., Rocky Mountain juniper (Juniperus scopulorum), saltbush (Atriplex species), greasewood (Sarcobatus vermiculatus), rubber rabbitbrush (Ericameria nauseosa) or green rabbitbrush (Chrysothamnus viscidiflorus). Perennial herbaceous cover is usually grasses, although this will vary depending on the other species present and influencing disturbance factors.

Diagnostic Characteristics

Shrubland dominated, lowland elevations, plains, alluvial plains, shallow fine to coarse textured soils, xeromorphic shrubs, shrub cover greater than 10%, Artemsisia tridentata ssp. tridentata, Artemsisia tridentata ssp. wyomingensis, herbaceous cover less than 25 percent

Similar Systems

This system occurs throughout much of the western U.S., typically in broad basins between mountain ranges, and on plains and and foothills. It occurs as far east as central and eastern Montana, although most of the sagebrush systems in the east are more properly characterized as steppe.

Ecological System Distribution
Approximately 5 square kilometers are classified as Big Sagebrush Shrubland in the 2017 Montana Land Cover layers.  Grid on map is based on USGS 7.5 minute quadrangle map boundaries.

Montana Counties of Occurrence
Big Horn, Carbon, Lewis and Clark, Teton

Spatial Pattern
Large or Small Patch

This system occurs as an extensive matrix on level to gently rolling plains, on toeslopes and in valley bottoms, as well as in small and large patches in dissected landscapes such as breaks and badlands. It is found in broad basins between mountain ranges, on plains and on foothills between 670 and 1,066 meters (2,200-3,500 feet). It can occur on all aspects. Soils are shallow, fine to coarse textured, well drained and non-saline, developed from various parent materials that have weathered to predominantly heavy-textured, clay-rich Aridisols, and in more mesic conditions, Mollisols. In southeastern Montana, these sites are associated with heavy soils developed from shales and mudstones. In north-central Montana, soils tend to be shallower, often with gravelly or claypan surfaces.


In Montana, this system occurs as a result of historic and current overgrazing practices and can be considered a disclimax expression of sagebrush steppe. These shrublands are dominated by big sagebrush (Artemisia tridentata ssp. tridentata) and/or more commonly, Wyoming big sagebrush (Artemisia tridentata ssp. wyomingensis). In some occurrences there are scattered Rocky Mountain juniper (Juniperus scopulorum), greasewood (Sarcobatus vermiculatus), and saltbush (Atriplex species). Rubber rabbitbrush (Ericameria nauseosa) and green rabbitbrush (Chrysothamnus viscidiflorus) may codominate in recently burned stands.

By definition, perennial herbs contribute less than 25% of the vegetative cover (NatureServe 2009) and consist mostly of graminoids, which can vary greatly in composition, depending on the surrounding vegetation type. Dominant grasses can be either rhizomatous or bunch grasses. Perennial forb diversity is quite variable depending on site and treatment; with livestock use the number of introduced species can easily exceed eight on a given site. Common graminoid species can include Indian ricegrass (Achnatherum hymenoides), blue grama (Bouteloua gracilis), threadleaf sedge (Carex filifolia), thickspike wheatgrass (Elymus lanceolatus), needle and thread (Hesperostipa comata), basin wildrye (Leymus cinereus), western wheatgrass (Pascopyrum smithii), Sandberg’s bluegrass (Poa secunda), or bluebunch wheatgrass(Pseudoroegneria spicata). Bluebunch wheatgrass- bunchgrass dominated sites are most prevalent in western Montana. Sod-forming species such as thickspike wheatgrass and western wheatgrass are more common in the eastern portion of the state. Common forbs include yarrow (Achillea millefolium), arrowleaf balsamroot (Balsamorhiza sagittata), scarlet globe mallow (Sphaeralcea coccinea), American vetch (Vicia americana), and plains prickly pear (Opuntia polyacantha) on especially xeric sites. Within this system, cheatgrass (Bromus tectorum) or other annual bromes and invasive weeds can be abundant.

National Vegetation Classification Switch to Full NVC View

Adapted from US National Vegetation Classification

A3179 Purshia tridentata - Artemisia tridentata Mesic Steppe & Shrubland Alliance
A3182 Artemisia tridentata ssp. Wyomingensis Mesic Steppe & Shrubland Alliance
CEGL001009 Artemisia tridentata ssp. wyomingensis - Pseudoroegneria spicata Shrubland
CEGL001047 Artemisia tridentata ssp. wyomingensis - Pascopyrum smithii Shrub Grassland
CEGL001049 Artemisia tridentata ssp. wyomingensis - Poa secunda Shrubland
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
CEGL001041 Artemisia tridentata ssp. wyomingensis - Bouteloua gracilis Shrubland
CEGL001042 Artemisia tridentata ssp. wyomingensis - Carex filifolia Shrubland
CEGL001044 Artemisia tridentata ssp. wyomingensis - Elymus albicans Shrubland
A3196 Ericameria nauseosa Steppe & Shrubland Alliance
A3198 Artemisia tridentata - Mixed Shrub Dry Steppe & Shrubland Alliance
A3202 Krascheninnikovia lanata Steppe & Dwarf-shrubland Alliance
CEGL001327 Krascheninnikovia lanata - Hesperostipa comata Dwarf-shrubland
A3207 Artemisia tridentata ssp. spiciformis - Artemisia tridentata ssp. Vaseyana Steppe & Shrubland Alliance
CEGL001028 Artemisia tridentata ssp. vaseyana - Pascopyrum smithii Shrubland
A4213 Artemisia spp. - Mixed Shrub Ruderal Understory Shrubland Alliance
*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 sagebrush systems maintains a patchy distribution of shrubs, so in disturbance-free areas, steppe systems would be typical.. However, shrubs increase following heavy grazing and/or with fire suppression. Heavy grazing can lead to a decrease in native bunchgrasses and an increase in exotic grasses such as Kentucky bluegrass (Poa pratensis) and other species.

Big sagebrush is easily killed by fire at all intensities, and when exposed to fire, plants do not re-sprout (Wright and others 1979). In southwestern Montana, researchers have found that fire in mountain 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 (Wambolt et al. 2001, Lesica et al. 2005). In Montana, Wyoming big sagebrush may require a century or longer to recover from fire (Lesica et al. 2005).

Heavy grazing practices have also led to a decrease in native grasses and an increase in the spread of annual bromes in some areas of Montana. 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 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, to increase herbaceous forage and to improve habitat quality for sage grouse and other wildlife by creating a mosaic of burned and unburned patches. Researchers in southwestern Montana found that prescribed fire resulted in an average increase of 13% in grass canopy cover, so followed by light grazing, fire may be a way of rejuvenating mountain big sagebrush stands. Furthermore, prescribed fire or wildfire will cause only a small increase in the cover of forbs overall, and will have no effect on the abundance of plants in the Cichorieae tribe of the Asteraceae, an important food source for rearing sage grouse broods (Lesica et al, 2005). Excessive grazing can result in the loss of the most common perennial grasses in this system and promote the spread of cheatgrass.

Restoration Considerations

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

Version Date

  • Classification and Map Identifiers

    Cowardin Wetland Classification: Not applicable

    NatureServe Identifiers:
    Element Global ID 28615
    System Code CES304.777, Inter-Mountain Basins Big Sagebrush Shrubland

    5257: Inter-Mountain Basins Big Sagebrush Shrubland

  • 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.
    • NatureServe. NatureServe Explorer: Inter-Mountain Basins Big Sagebrush Shrubland.
    • 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.

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