Basin and Wyoming Big (Threetip) Sagebrush Shrubland
Global Name:
Intermountain Basins Big Sagebrush Steppe
Global Rank:
G3?
State Rank:
S3
(see reason below)
External Links
State Rank Reason
This group is widespread on the landscape but has undergone conversion to grasslands and agriculture. Habitat conditions have been degraded by non-native species and from grazing practices. Habitats do not quickly recover to sagebrush following wildfires, which have become more frequent and widespread.
General Description
This National Vegetation Classification Group is a xeric shrubland group that is widespread and sometimes a landscape dominant east of the Continental Divide. It is primarily dominated by Wyoming Big Sagebrush communities, though it also includes more localized communities dominated by Basin Big Sagebrush in southwest Montana and by small patches of Threetip Sagebrush or Antelope Bitterbrush. Shrub cover is sparse to dense and consists of shrubs typically 1-3ft. tall, though heights may be up to twice that in the case of Basin Big Sagebrush.
Other shrub species are occasionally present. Perennial, herbaceous species typically contribute greater than 25% vegetative cover and often consists of both rhizomatous and bunch-forming graminoids, with a diversity of perennial forbs. These habitats typically occur in broad basins between mountain ranges, and on plains and in the foothills. Typical elevations are from 3,000-5,000ft for Wyoming Big Sagebrush communities though the group extends to elevations of approx 7,000ft for communities dominated by Antelope Bitterbrush, Basin Big Sagebrush and Threetip Sagebrush. The group 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 can occur on all aspects. Soils are shallow, fine to coarse textured, well drained and mostly non-saline.
Some communities in this group provide important wildlife habitat for species such as Sage Grouse and Pronghorn as well as many other animal and plant species.
This group encompasses the Big Sagebrush Steppe and the Big Sagebrush Shrubland Ecological Systems.
Diagnostic Characteristics
Semi-Arid Shrubland and Steppe; Intermountain and Great Plains Regions; Valleys, Plains, Foothills; Xeromorphic Shrubs, Shrub Cover >10%
Typical Dominants: Basin Big Sagebrush (Artemisia tridentata ssp. tridentata), Wyoming Big Sagebrush (Artemisia tridentata ssp. wyomingensis), Threetip Sagebrush (Artemisia tripartita), Antelope Bitterbrush (Purshia tridentata)
Similar Systems
Range
This group occurs primarily east of the Continental Divide in the Intermountain Valleys, Bighorn Basin and in the Great Plains. In the lower elevation valleys of southwest Montana, Wyoming Big Sagebrush is a common community. Basin Big Sagebrush communities are restricted mainly to stream terraces in Beaverhead County. On the Great Plains and in the foothills, Wyoming Big Sagebrush Steppe can be found in localized patches to widespread areas on the landscape where it has not been eradicated by agricultural practices or fire. In southwest Montana, including in areas west of the Continental Divide such as the Foothills surrounding the Bitterroot Valley, this Group is represented by small patches of Antelope Bitterbrush. Threetip Sagebrush communities are confined primarily to Beaverhead County.
In Montana, G302 occurs in Level III Ecoregions: 16 (Idaho Batholith), 17 (Middle Rockies), 18 (Wyoming Basin), 42 (Northwestern Glaciated Plains) and 43 (Northwestern Great Plains).
In Montana, G302 occurs or potentially occurs within these Major Land Resource Areas: 43B - Central Rocky Mountains, 44A - Northern Rocky Mountain Valleys, 44B - Central Rocky Mountain Valleys, 46 Northern and Central Rocky Mountain Foothills, 52 - Brown Glaciated Plains; 53A - Northern Dark Brown Glaciated Plains, 58A,B,C,D - Northern Rolling High Plains, 60A,B - Pierre Shale Plains.
Density and Distribution
Based on 2025 land cover layer. Grid on map is based on USGS 7.5 minute quadrangle map boundaries.
Mapped Distribution by County
Beaverhead, Big Horn, Blaine, Broadwater, Carbon, Carter, Cascade, Chouteau, Custer, Dawson, Deer Lodge, Fallon, Fergus, Gallatin, Garfield, Golden Valley, Granite, Hill, Jefferson, Judith Basin, Lake, Lewis and Clark, Madison, Mccone, Meagher, Missoula, Musselshell, Park, Petroleum, Phillips, Powder River, Powell, Prairie, Ravalli, Richland, Rosebud, Silver Bow, Stillwater, Sweet Grass, Treasure, Valley, Wheatland, Wibaux, Yellowstone
Based on 2025 land cover layer.
Spatial Pattern
Matrix
Environment
This group occurs throughout much of the western U.S., typically in broad basins between mountain ranges, and on plains and in the foothills. Typical elevations are from 3,000-5,000ft for Wyoming Big Sagebrush communities though the group extends to elevations of approx 7,000ft for communities dominated by Antelope Bitterbrush, Basin Big Sagebrush and Threetip Sagebrush. The group 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 can occur on all aspects. Soils are shallow, fine to coarse textured, well drained and mostly non-saline. They 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.
Vegetation
In Montana, these communities are dominated by Wyoming Big Sagebrush (Artemisia tridentata ssp. wyomingensis), Basin Big Sagebrush (Artemisia tridentata ssp. tridentata) or occasionally by Threetip Sage (Artemisia tripartita), or Antelope Bitterbrush (Purshia tridentata). Other shrubs may be present, including Silver Sagebrush (Artemisia cana), Black Greasewood (Sarcobatus vermiculatus), Shadscale (Atriplex species), Rubber Rabbitbrush (Ericameria nauseosa), and Green Rabbitbrush (Chrysothamnus viscidiflorus) depending on specific site characteristics. Shrub cover can vary significantly and stands may be open to dense. Shrub heights are typically 1-3ft., though heights may be up to twice that in the case of Basin Big Sagebrush.
Perennial herbaceous components typically contribute greater than 25% vegetative cover and consists of rhizomatous and bunchforming graminoids, with a diversity of perennial forbs. In Montana, the dominant graminoids include Western Wheatgrass (Elymus smithii), Bluebunch Wheatgrass (Elymus spicatus), Indian Ricegrass (Oryzopsis hymenoides), Needle-and-Thread (Stipa comata), blue grama (Bouteloua gracilis), Sandberg’s Bluegrass (Poa secunda). Dryland rhizomatous sedges such as threadleaf sedge (Carex filifolia) and needleleaf sedge (Carex duriuscula) are common at some sites.
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 group, cheatgrass (Bromus tectorum), Japanese brome (Bromus japonicus) and other invasive weeds can be abundant where there is frequent disturbance.
In Montana, this group encompasses 21 Associations grouped into 5 Alliances within the National Vegetation Classification. These likely cover the range of variation within vegetation communities in Wyoming Big Sagebrush dominated communities in the state.
National Vegetation Classification
Download the complete NVC hierarchy for Montana
TT5 B05 Desert and Semi-desert
TT5.a S61 Cool Semi-desert
TT5.a1 F121 Cool Desert and Semi-desert Shrub-Steppe
TT5.a1.Na D040 Western North American Cool Semi-Desert Scrub and Grassland
TT5.a1.Na.3 M169 Great Basin-Intermountain Tall Sagebrush Steppe
TT5.a1.Na.3.b G302 Intermountain Basins Big Sagebrush Steppe
A1528 Artemisia tripartita ssp. tripartita Shrub Steppe 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
A2163 Artemisia tridentata ssp. wyomingensis Dry Shrub Steppe Alliance
CEGL001042 Artemisia tridentata ssp. wyomingensis / Carex filifolia Shrubland
CEGL001044 Artemisia tridentata ssp. wyomingensis / Elymus albicans Shrubland
CEGL001047 Artemisia tridentata ssp. wyomingensis / Pascopyrum smithii Shrub Grassland
CEGL001049 Artemisia tridentata ssp. wyomingensis / Poa secunda Shrubland
CEGL005477 Artemisia tridentata ssp. wyomingensis / Bromus tectorum Ruderal Shrubland
A2265 Purshia tridentata Shrub Steppe 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
A2302 Artemisia tridentata / Pascopyrum smithii Shrub Grassland Alliance
CEGL008295 Artemisia tridentata ssp. wyomingensis / Bouteloua gracilis Northwestern Plains Shrubland
CEGL008299 Artemisia tridentata ssp. wyomingensis / Pascopyrum smithii - Pseudoroegneria spicata Shrub Grassland
A3182 Artemisia tridentata ssp. wyomingensis Dry-Mesic Shrub Steppe Alliance
CEGL001009 Artemisia tridentata ssp. wyomingensis / Pseudoroegneria spicata Shrubland
CEGL001535 Artemisia tridentata ssp. wyomingensis / Pseudoroegneria spicata Shrub Grassland
CEGL005478 Artemisia tridentata ssp. wyomingensis / Festuca idahoensis Shrubland
A3183 Artemisia tridentata ssp. tridentata - Artemisia tridentata ssp. xericensis Shrub Steppe 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
*Disclaimer: Some Alliances and Associations are considered provisional. Some require further documentation to verify their occurrence in the state
and some may be modified or deleted in future revisions after collection of additional data and information.
Dynamic Processes
The natural fire regime of sagebrush habitats 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 group by increasing fire potential, severity and spread.
Management
Some communities in this group provide important wildlife habitat for species such as Sage Grouse and Pronghorn as well as many other animal and plant species. In the absence of natural fire, periodic prescribed burns can be used to maintain and restore this group 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; followed by light grazing, fire may be a way of rejuvenating mountain big sagebrush stands. Furthermore, prescribed fire or wildfire generally causes 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 group and promote the spread of cheatgrass.
In the absence of natural fire, periodic low intensity prescribed burns can be used to maintain and restore this group 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 group and lead to an abundance of Cheatgrass or Japanese Brome.
Restoration Considerations
Severely burned sites may require replanting with Wyoming 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 sagebrush has 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.
Successful restoration of native grasses within this group 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 wheatgrass seedlings 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.
Species Associated with this Community
- How Lists Were Created and Suggested Uses and Limitations
Animal Species Associations
Please note that while all vertebrate species have been systematically associated with vegetation communities, only a handful of invertebrate species have been associated with vegetation communities and invertebrates lists for each vegetation community should be regarded as incomplete. Animal species associations with natural vegetation communities that they regularly breed or overwinter in or migrate through were made by:
- 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, Werner et al. 2004, Adams 2003, and Foresman 2012);
- Evaluating structural characteristics and distribution of each vegetation community relative to the species' range and habitat requirements;
- Examining the observation records for each species in the state-wide point observation database associated with each vegetation community;
- Calculating the percentage of observations associated with each vegetation community relative to the percent of Montana covered by each vegetation community 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. Species that only migrate through Montana were only evaluated for migratory habitat use. In general, species are listed as associated with a vegetation community if it contains structural characteristics known to be used by the species. However, species are not listed as associated with a vegetation community if we found no support in the literature for the species’ use of structural characteristics of the community even if point observations were associated with it. If you have any questions or comments on animal species associations with vegetation communities, please contact the Montana Natural Heritage Program's Senior Zoologist.
Plant Species Associations
Please note that while diagnostic, dominant, or codominant vascular plant species for a vegetation community have been systematically assigned to those communities and vascular plant Species of Concern were systematically evaluated for their associations with vegetation communities, the majority of Montana’s vascular plant species have not been evaluated for their associations with vegetation communities and no attempt has been made to associate non-vascular plants, fungi, or lichens with vegetation communities. Plant species associations with natural vegetation communities were made in a manner similar to that described above for animals, but with review of Lesica et al. (2022) and specimen collection data from the Consortium of Pacific Northwest Herbaria. If you have any questions or comments on plant species associations with vegetation communities, please contact the Montana Natural Heritage Program's Program Botanist.
Suggested Uses and Limitations
Species associations with vegetation communities 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 or predicted habitat suitability models (this information can be requested at: https://mtnhp.mt.gov/requests/), or systematic surveys for species and onsite evaluations of habitat by trained biologists. Users of this information should be aware that the land cover data used to generate species associations is based on satellite imagery from 2016 and was only intended to be used at broader landscape scales. Land cover mapping accuracy is particularly problematic when the vegetation communities 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 vegetation community within its known geographic range, portions of that vegetation community 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.
- Consortium of Pacific Northwest Herbaria. https://www.pnwherbaria.org/ Last accessed May 30, 2025.
- 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.
- Lesica P., M. Lavin, and P.F. Stickney. 2022. Manual of vascular plants, 2nd Edition. Brit Press. 779 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.
- Species of Concern Associated with this Community
Vascular Plants
Mammals
Birds
Reptiles
Amphibians
- Diagnostic, Dominant, or Codominant Plant Species for this Community
Vascular Plants
- Other Native Species Commonly Associated with this Community
Vascular Plants
Original Concept Authors
M.E. Hall and K.A. Schulz 2015
Montana Version Authors
S. Mincemoyer, L. Vance, T. Luna, S.V. Cooper
Version Date
12/5/2024
References
- Literature Cited AboveLegend:
View Online Publication- 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.
- 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. 2004. 'Sagebrush (Artemisia spp.) Seed and Plant Transfer Guidelines'. Native Plants Journal. 5 (2): 141-148.- 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.
- Additional ReferencesLegend: View Online Publication
Do you know of a citation we're missing?- 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.
- Shiflet, T. N., editor. 1994. Rangeland cover types of the United States. Society for Range Management. Denver, CO. 152 pp.
- West, N. E. 1983c. Western Intermountain sagebrush steppe. Pages 351-374 in: N. E. West, editor. Temperate deserts and semi-deserts. Ecosystems of the world, Volume 5. Elsevier Publishing Company, Amsterdam.
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