Greasewood Shrubland
Global Name:
North American Desert Alkaline-Saline Wet Scrub
Global Rank:
G4G5
State Rank:
S4
(see reason below)
External Links
State Rank Reason
Habitat condition has been negatively impacted by the combination of livestock grazing and invasive species, though the type is likely not as vulnerable to impacts as some other habitats and it is relatively widespread.
General Description
This National Vegetation Classification Group is a minor type that occurs in the valleys of southwest Montana, in the Bighorn Basin in Carbon County and on the Great Plains of central and eastern MT. These communities usually consist of open to moderately dense shrubs dominated by Black Greasewood (Sarcobatus vermiculatus) with a sparse graminoid understory. It is found on nearly level, older alluvial terraces on broad or narrow floodplains and alluvial fans in valley bottoms. It may also occur on broad expanses along lake shores and playas. Sites typically have saline or alkaline soils and a shallow water table. They flood intermittently, but the surface is dry for most of the growing season. The water table remains high enough to maintain vegetation, despite salt accumulations. In many cases, fine textured soils result in a perched water table.
As originally defined, this group is limited to arid regions of the Intermountain West, including southwest Montana and the Bighorn Basin with greasewood communities in the Great Plains Region included in G566 (Great Plains Sparsely-Vegetated Badlands) or G984 (Great Plains Saline Wet Meadow & Marsh). However, greasewood communities are mapped by NatureServe and in the Montana Landcover Layer as continuing onto the Great Plains. As such, the concept adopted here does not specifically limit these communities to the Intermountain West.
This group encompasses the portion of the Greasewood Flat Ecological System that occurs in the Intermountain Basins of southwest MT and in the Bighorn Basin in south-central MT.
Diagnostic Characteristics
Alkaline and Saline Shrubland; Lowlands, Toeslope and Valley Bottoms, Deep Silt and Clay Soils, Intermountain and Bighorn Basin Regions, Great Plains.
Typical Dominants: Black Greasewood (Sarcobatus vermiculatus)
Similar Systems
Range
This group occurs in the valleys of southwest Montana, the Bighorn Basin in Carbon County and on the Great Plains of central and eastern MT.
In Montana, G537 occurs in Level IV Ecoregions: 18b (Bighorn Basin), 43v (Pryor-Bighorn Foothills) and 17aa (Dry Intermontane Sagebrush Valleys) and in Level III Ecoregions: 42 (Northwestern Glaciated Plains) and 43 (Northwestern Great Plains).
In Montana, G537 occurs or potentially occurs within these Major Land Resource Areas: 32 - Northern Intermountain Desertic Basins, 44B - Central Rocky Mountain Valleys, 46 - Northern and Central Rocky Mountain Foothills, 52, 53A - Northern Dark Brown Glaciated Plains, 58A, B, C - Northern Rolling High Plains, and 60A and 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, Daniels, Dawson, Deer Lodge, Fallon, Fergus, Gallatin, Garfield, Glacier, Golden Valley, Granite, Hill, Jefferson, Judith Basin, Lewis and Clark, Liberty, Madison, Mccone, Meagher, Musselshell, Park, Petroleum, Phillips, Pondera, Powder River, Powell, Prairie, Ravalli, Richland, Roosevelt, Rosebud, Sheridan, Silver Bow, Stillwater, Sweet Grass, Teton, Toole, Treasure, Valley, Wheatland, Wibaux, Yellowstone
Based on 2025 land cover layer.
Spatial Pattern
Small Patch and Large Patch
Environment
In Montana, this group represents one of the driest extremes of the riparian/wetland zone. It occurs on nearly level, older alluvial terraces on broad or narrow floodplains and alluvial fans in valley bottoms. It may also occur on broad expanses along lake shores and playas. Sites typically have saline or alkaline soils and a shallow water table. They flood intermittently but remain dry for most of the growing season. However, the underlying water table stays high enough to maintain vegetation, despite salt accumulations. The group occurs where overland flow or soils or a combination of both allow for a greater than normal moisture regime. High water tables are common, typically within 10 to 12 inches of the soil surface. Soils are fine textured and range from silt to clay.
Vegetation
Black Greasewood (Sarcobatus vermiculatus) is the dominant shrub, although overall canopy cover may be low. Other shrubs present in some occurrences include Fourwing Saltbush (Atriplex canescens), Shadscale (Atriplex confertifolia), Gardner’s Saltbush (Atriplex gardneri), Wyoming Big Sagebrush (Artemisia tridentata ssp. wyomingensis), Basin Big Sagebrush (Artemisia tridentata ssp. tridentata), Silver Sage (Artemisia cana ssp. cana), Green Rabbitbrush (Chrysothamnus viscidiflorus), Rubber Rabbitbrush (Ericameria nauseosa) or Winterfat (Krascheninnikovia lanata).
Perennial grasses are the most common herbaceous cover, with Western Wheatgrass (Elymus smithii) tending to dominate in undisturbed communities. Other graminoids commonly occurring in this group include Slender Wheatgrass (Elymus trachycaulus), Nutall’s Alkaligrass (Puccinellia nuttalliana), Sandberg’s Bluegrass (Poa secunda), Inland Saltgrass (Distichlis spicata), Alkali Sacaton (Sporobolus airoides), Prairie Sandreed (Calamovilfa longifolia), and Basin Wildrye (Elymus cinereus). Common forb species include yarrow (Achillea millefolium), Goldenweed (Pyrrocoma uniflora), Fringed Sage (Artemisia frigida), Western Sagewort (Artemisia ludoviciana), Goosefoot (Chenopodium species), Scarlet Globemallow (Sphaeralcea coccinea), Western Saltwort (Salicornia rubra) and Curlycup Gumweed (Grindelia squarrosa).
Adjacent drier communities are dominated by upland shrub or grassland communities such as Salt Desert Scrub or Big Sagebrush (Artemisia tridentata) shrublands. Wetter adjacent communities may be dominated by Inland Saltgrass (Distichlis spicata) or willow-cottonwood (Salix-Populus species) dominated communities.
In Montana, this group is represented by 1 Alliance with 4 Associations within the National Vegetation Classification, which likely cover the diversity of types within this group. Black Greasewood communities within the Great Plains Region are part of either G566 - Great Plains Sparsely-Vegetated Badlands or G984 - Great Plains Saline Marsh & Wet Meadow.
National Vegetation Classification
Download the complete NVC hierarchy for Montana
TP1 B08 Palustrine Wetland
TP1.b S70 Emergent Open Wetland
TP1.b3 F139 Inland Salt Marsh
TP1.b3.Nb D036 Western North American Inland Saline Marsh
TP1.b3.Nb.1 M082 North American Desert Alkali-Saline Marsh, Playa and Shrubland
TP1.b3.Nb.1.b G537 Desert Alkaline-Saline Wet Scrub
A1046 Sarcobatus vermiculatus Intermountain Shrubland Alliance
CEGL001359 Sarcobatus vermiculatus - Artemisia tridentata Wet Shrubland
CEGL001360 Sarcobatus vermiculatus / Atriplex gardneri Wet Shrubland
CEGL001363 Sarcobatus vermiculatus / Distichlis spicata Wet Shrubland
CEGL001366 Sarcobatus vermiculatus / Leymus cinereus Wet 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
Soil-water dynamics within these communities support a restricted range of species. Communities in good condition typically have 30 to 40 % shrub cover. Under continued disturbance, greasewood and western wheatgrass decrease in cover, while species such as foxtail barley (Hordeum jubatum) and yarrow (Achillea millefolium), and exotics like cheatgrass (Bromus tectorum), Japanese brome (Bromus japonicus) and Kentucky bluegrass (Poa pratensis), increase in cover.
Management
Overgrazing practices can significantly impact vigor and cover of the principal shrub species, leading to an increase in cheatgrass and other exotics, although herbaceous cover in this group is often too low to attract cattle away from surrounding uplands. Off-road travel can be a disturbance, especially in the early season, when clayey soils are still soft. In any season, heavy off-road travel can be harmful to the very slow growing dominant shrub species.
Restoration Considerations
In cases where the habitat has been impacted by heavy grazing, a rest-rotation regime with limited fall grazing may allow this habitat to recover by allowing regrowth of principal graminoid and shrub species. Severely impacted sites should be re-seeded to decrease soil erosion potential, to re-establish a native community, and to decrease weedy invasion by exotic species. Western Wheatgrass can be used as the principal restoration species and can be seeded or transplanted as plugs. Once established this species spreads vigorously by rhizomes. Both Greasewood and Western Wheatgrass exhibit excellent soil erosion control characteristics. Replanting with Greasewood seedlings may be necessary due to the slow recovery time within this habitat and low rates of natural seedling recruitment.
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
Invertebrates
- Diagnostic, Dominant, or Codominant Plant Species for this Community
Vascular Plants
- Other Native Species Commonly Associated with this Community
Vascular Plants
Original Concept Authors
G. Kittel 2015
Montana Version Authors
S. Mincemoyer, C. McIntyre, L. Vance, T. Luna
Version Date
12/5/2024
References
- Additional ReferencesLegend:
View Online Publication
Do you know of a citation we're missing?- 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.
Shiflet, T. N., editor. 1994. Rangeland cover types of the United States. Society for Range Management. Denver, CO. 152 pp.- West, N. E. 1983b. Intermountain salt desert shrublands. Pages 375-397 in: N. E. West, editor. Temperate deserts and semi-deserts. Ecosystems of the world, Volume 5. Elsevier Publishing Company, Amsterdam.
- Web Search Engines for Articles on "North American Desert Alkaline-Saline Wet Scrub"
