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Montana Field Guide

Montana Field Guides

Mixed Salt Desert Scrub

Provisional State Rank: S1
* (see reason below)

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State Rank Reason
This is a very limited system within Montana, with small patches occuring in the Wyoming Basin ecoregion. Its state rank is based on its limited distribution; nationally it is more secure.
 

General Description

This is a very minor ecological system found in southeastern Montana at elevations of 1,065- 1,220 meters (3,500-4,000 feet) on steep-facing erodible badlands. The environment in this region of Montana is characterized by annual precipitation of 12 inches or less, warm to hot summers and cold winters with variable amounts of snow cover. Soils on sites supporting this system are alkaline or saline Entisols. This shrub- dominated community typically contains one or more saltbush (Atriplex) species, such as shadscale saltbush (Atriplex confertifolia) or fourwing saltbush (Atriplex canescens). Some occurrences contain a mixture of saltbush species and Wyoming sagebrush (Artemisia tridentata ssp. wyomingensis) and other shrub species. The understory is dominated by grasses, e.g, Indian ricegrass (Achnatherum hymenoides), blue grama (Bouteloua gracilis), western wheatgrass (Pascopyrum smithii), Sandberg’s bluegrass (Poa secunda), alkali sacaton (Sporobolus airoides), needle and thread (Hesperostipa comata), saline wild rye (Leymus salinus), bluebunch wheatgrass (Pseudoroegneria spicata) and inland saltgrass (Distichlis spicata). Forb cover is generally very low. Disturbances within this system may lead to an increase in invasive annual grasses and forbs.


Diagnostic Characteristics

Lowland, alluvial flat, alluvial plain, plains, badland, shrubland, alkaline soil, saline substrate chemistry, calcareous, silt or clay soil texture, xeromorphic shrub, dwarf-shrub, Atriplex species


Similar Systems

Range
This system occurs in Montana on steep facing, erodible badlands in Carbon County at 1,065-1,220 meters (3,500-4,000 feet), but it is not well developed or represented. In Wyoming, it occurs in the Great Divide and Bighorn Basins. Elsewhere, it occurs throughout the western interior and intermountain United States, and in areas of the southern Great Plains in eastern New Mexico.

Ecological System Distribution
Approximately 1 square kilometers are classified as Mixed Salt Desert Scrub in the 2016 Montana Land Cover layers.  Grid on map is based on USGS 7.5 minute quadrangle map boundaries.



Montana Counties of Occurrence
Big Horn, Carbon, Gallatin, Park

Spatial Pattern
Matrix

Environment
This is typically a system of extreme climatic conditions, with warm to hot summers and freezing winters. In Montana, annual precipitation is generally 30 centimeters (12 inches) or less. Precipitation usually occurs in spring after snowmelt as intermittent spring rains and sometimes during late summer or fall. Soils are shallow to moderately deep, poorly developed, and a product of an arid climate with little precipitation. Soils are often alkaline or saline, poorly developed Entisols.

Vegetation

Vegetation is composed of one or more saltbush (Atriplex) species, such as shadscale saltbush (Atriplex confertifolia) or fourwing saltbush (Atriplex canescens). Some occurrences contain a mixture of saltbush species and Wyoming sagebrush (Artemisia tridentata ssp. wyomingensis). Spiny hopsage (Grayia spinosa) tends to occur on silty coppice dunes. Other shrubs may include winterfat (Krascheninnikovia lanata), green rabbitbrush (Chrysothamnus viscidiflorus), rubber rabbit brush (Ericameria nauseosa), broom snakeweed (Gutierrezia sarothrae),budsage brush (Picrothamnus desertorum), shortspine horse brush (Tetradymia spinosa) andsoapweed yucca (Yucca glauca).Prickly pear (Opuntia species) may be present in some occurrences. Trees are not usually present, but some scattered RockyMountain juniper (Juniperus scopulorum) may be found.

Graminoids dominate the sparse, or sometimes moderately dense, herbaceous understory. Species present depends on habitat, the alkalinity/salinity of site and past land use, and may includeIndian ricegrass (Achnatherum hymenoides), blue grama (Bouteloua gracilis), western wheatgrass (Pascopyrum smithii), Sandberg’s bluegrass (Poa secunda), alkali sacaton (Sporobolus airoides), needle and thread (Hesperostipa comata), saline wild rye (Leymus salinus), bluebunch wheatgrass (Pseudoroegneria spicata) and

Inland saltgrass (Distichlis spicata). Forb cover is generally very low. Annual native species are common on recently disturbed sites within this system and include species such as plantain (Plantago species), sixweeks fescue (Vulpia octoflora), or Nuttall’s povertyweed (Monolepis nuttalliana). Halophytic annuals include western glasswort (Salicornia rubra)and seepweed (Suaeda species). Perennial forbs may include boreal sagewort (Artemisia frigida), scarlet globe mallow (Sphaeralcea coccinea),and blazing star (Mentzelia species). Exotic annuals such as Russian thistle (Salsola kali) and cheatgrass (Bromus tectorum) are frequently found in this system.


National Vegetation Classification Switch to Full NVC View

Adapted from US National Vegetation Classification

A0870 Atriplex confertifolia Scrub Alliance
CEGL001293 Atriplex confertifolia Wyoming Basins Shrubland
CEGL001300 Atriplex confertifolia - Ericameria nauseosa Shrubland
CEGL001452 Picrothamnus desertorum Shrubland
A3198 Artemisia tridentata - Mixed Shrub Dry Steppe & Shrubland Alliance
CEGL001040 Artemisia tridentata ssp. wyomingensis / Atriplex confertifolia Shrubland
A3202 Krascheninnikovia lanata Steppe & Dwarf-shrubland Alliance
CEGL001327 Krascheninnikovia lanata - Hesperostipa comata Dwarf-shrubland
*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

Species of the salt-desert shrub complex have different degrees of tolerance to salinity and aridity, and so tend to sort themselves out along a moisture/salinity gradient (West 1982). The harsh environmental conditions of these systems slow down community dynamics. The same species or species similar in stature or appearance often succeed each other after disturbances. Fire frequency was historically very low in this system. Heavy sheep grazing practices can significantly impact vigor and cover of the principal shrub species, leading to an increase of annual bromes (Bromus species) and other exotic annual forbs. Sites invaded with exotic annuals are changing the dynamics of this system by increasing fire potential, severity and spread.


Management
Historically, fire was rare in this system due to the characteristic low plant cover. Excessive grazing can result in the demise of the most common perennial grasses in this system and lead to an abundance cheatgrass and other invasive annuals. Off-road vehicle travel can be a significant disturbance.

Restoration Considerations
Natural regeneration of saltbush species and their associates occurs where old plants existed in the interspaces, due to accumulated organic matter and nutrients and more favorable moisture (West, 1982). Shrub seedlings should be planted in these microsites, where and when they exist on a restoration site, to improve survival rates. Dominant species have been used to stabilize soils and to reclaim disturbed sites (Carlson et al, 1984).

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: http://mtnhp.org/requests/default.asp) 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
T. Luna and L.K. Vance

Version Date
1/1/2017

References
  • Classification and Map Identifiers

    Cowardin Wetland Classification: Not applicable

    NatureServe Identifiers:
    Element Global ID 28622
    System Code CES304.784, Inter-Mountain Basins Mixed Salt Desert Scrub

    ReGAP:
    5258: Inter-Mountain Basins Mixed Salt Desert Scrub


  • Additional ReferencesLegend:   View Online Publication
    Do you know of a citation we're missing?
    • Carlson, J. R., J. G. Schutz, and W. R. Oaks. 1983. Seed production technique of two chenopods: Gardner saltbush and winterfat. Pp. 191-195 in A. R. Tiedemann, E. D. McArthur, H. C. Stutz, R. Stevens, and K. C. Johnson, comps., Proc. Symposium on the Biology of Atriplex and related chenopods. USDA For. Serve Gen. Tech. Rep. INT-172. 309 pp.
    • West NE. 1982. Dynamics of plant communities dominated by chenopod shrubs. Internationl Journal and Ecology and Environmental Science(8):73-84.

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Citation for data on this website:
Mixed Salt Desert Scrub — Inter-Mountain Basins Mixed Salt Desert Scrub.  Montana Field Guide.  Retrieved on , from