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Rocky Mountain Lower Montane-Foothill Shrubland

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Provisional State Rank: S5
* (see reason below)

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State Rank Reason
This system may increase under drought and climate change scenarios, as intermittent streams become more ephemeral.
 

General Description

This shrubland system is found in the lower montane and foothill regions in the Rocky Mountains, including east into the island mountain ranges. It also occurs in southern Montana, where it forms compositionally diverse shrublands. It is common in foothills and lower slopes of mountain ranges, along higher creeks, and in draws and ravines of high plateaus on the northwestern Great Plains. The communities in this system grow at the interface between larger riparian areas and the adjacent upland shrublands and forests, usually occurring as small dense thickets, narrow bands, or irregular patches. The elevational range is 680 to 2,652 meters (2,234-8,700 feet). Shrub cover ranges from 30 to 100 percent. In Montana, chokecherry (Prunus virginiana) is frequently the dominant shrub species and on some sites, American plum (Prunus americana) may be solely present or co-dominant. Other shrubs associated with Prunus-dominated shrublands include currant (Ribes species), skunkbush sumac (Rhus trilobata), western snowberry (Symphoricarpos occidentalis), serviceberry (Amelanchier alnifolia), elderberry (Sambucus spp.), birchleaf spiraea (Spiraea betulifolia), andboreal sagewort (Artemisia frigida). Antelope bitterbrush (Purshia tridentata), creeping Oregon grape (Mahonia repens), and Woods rose (Rosa woodsii) may be present in some stands, along with scattered Rocky Mountain juniper (Juniperus scopulorum).


Diagnostic Characteristics
montane, lowland, shrubland, very shallow soil, aridic, intermediate disturbance interval

Similar Systems

Range
This shrubland system is found in the lower montane and foothill regions in the Rocky Mountains, including east into the island mountain ranges. It also occurs in southern Montana, where it forms compositionally diverse shrublands. It is frequently found on outcrops and canyon slopes east onto the western Great Plains. Elsewhere, it ranges from New Mexico north to Montana and South Dakota

Ecological System Distribution
Approximately 151 square kilometers are classified as Rocky Mountain Lower Montane-Foothill Shrubland in the 2013 Montana Land Cover layers.  Grid on map is based on USGS 7.5 minute quadrangle map boundaries.



Montana Counties of Occurrence
BEAVERHEAD, BIG HORN, CARBON, CARTER, CUSTER, DAWSON, DEER LODGE, FALLON, GALLATIN, GARFIELD, JEFFERSON, LEWIS AND CLARK, LINCOLN, MADISON, PARK, POWDER RIVER, PRAIRIE, ROSEBUD, SANDERS, SILVER BOW, SWEET GRASS, TREASURE, VALLEY, YELLOWSTONE

Spatial Pattern
Large patch

Environment
This is a widespread large or small-patch shrubland that is found throughout Montana. It occurs in the foothills and lower slopes of mountain ranges, along higher creeks, and in draws and ravines of high plateaus on the Great Plains. The elevational range is 680 to 2,652 meters (2,234-8,700 feet). Shrub cover ranges from 30 to 100 percent, and is generally higher in drainage bottoms and on lowermost slopes, and lower on upper slopes. The communities in this system grow at the interface between larger riparian areas and the adjacent upland shrublands and forests, usually occurring as small dense thickets, narrow bands, or irregular patches. They often occupies draws, ephemeral creeks in steep narrow-bottomed canyons, and shallow ravines. The system can occur on slopes below seeps and springs, as small pockets on higher terraces, as narrow bands along the high-water mark of steep banks and incised channels, or at the base of cliffs adjacent to rivers. Slope varies from flat to very steep, with variable aspects, and can be associated with rock outcrops and talus. Stands are typically found on very well-drained, rocky soils but occasionally have finer soils. Soil texture ranges from sandy loam to clay loam.

Vegetation

Stands can be dominated by one species but are often a mix of three to six shrub species, which can be as abundant or even more abundant than the dominant species. In Montana, for example, chokecherry is frequently the dominant shrub species and on some sites, American plum may be solely present or co-dominant. Other shrubs associated with Prunus-dominated shrublands include currant, skunkbush sumac, western snowberry, serviceberry, elderberry, birchleaf spiraea andboreal sagewort. Antelope bitterbrush, creeping Oregon grape, and Woods’ rose may be present in some stands, along with scattered Rocky Mountain juniper.

In drainage bottoms, herbaceous cover is usually less than 10 percent. On slopes, shrubs typically occur within grasslands, and graminoid cover can be greater than 75 percent. Graminoid species include mountain brome (Bromus carinatus), needle and thread (Hesperostipa comata), basin wildrye (Leymus cinereus), and bluebunch wheatgrass (Pseudoroegneria spicata). Mesic sites support forb species such ascow parsnip (Heracleum maximum) and starry Solomon’s seal (Maianthemum stellatum). Smooth brome (Bromusinermis), cheatgrass (Bromus tectorum), Kentucky bluegrass (Poa pratensis), and Canadian thistle (Cirsium arvense) are introduced species.


Alliances and Associations
Alliances
  • (A.825) Antelope Bitterbrush Shrubland Alliance
  • (A.919) Chokecherry Shrubland Alliance
  • (A.2565) Fringed Sagebrush Dwarf-shrubland Alliance
  • (A.2636) Shinyleaf Meadowsweet Shrubland Alliance
  • (A.1537) Skunkbush Sumac Shrub Herbaceous Alliance
  • (A.923) Wax Currant Shrubland Alliance
  • (A.961) Western Snowberry Temporarily Flooded Shrubland Alliance

Dynamic Processes
Fire impacts these shrublands at a frequency of every 50 to 100 years, but these systems will persist for longer periods. All shrub species regenerate following low to moderate intensity fires by re-sprouting from the root systems. Fire suppression may have allowed an invasion of trees into some of these shrublands, but in many cases sites are too xeric for tree growth. Under present conditions, the fire regime is mixed severity and more variable, with stand-replacing fires being more common in adjacent forested habitats. Heavy grazing impacts can limit productivity of associated graminoids and forbs, leading to the increasing spread of introduced grasses and invasive forbs.

Management
In the absence of natural fire, periodic prescribed burns can be used to maintain this system.

Restoration Considerations
Post-fire restoration strategies will depend largely on fire severity. Light to moderately burned areas usually recover quickly from fire; most dominant shrubs resprout from rhizomatous root systems and root crowns. In some cases, severely burned sites on very steep terrain may need to be reseeded to prevent soil erosion. Intense fires that occur during summer months cause considerable damage to these shrublands and seed banks.

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 (high, medium, or low) 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 2001, 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 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 associated as using 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 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.  High, medium, and low habitat quality was assigned based on the degree to which the structural characteristics of an ecological system matched the preferred structural habitat characteristics for each species in the 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 assignments of habitat quality.  If you have any questions or comments on species associations with ecological systems, please contact Bryce Maxell at bmaxell@mt.gov or (406) 444-3655.

    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.  2001.  The wild mammals of Montana.  Special Publication No. 12.  Lawrence, KS: The American Society of Mammalogists.  278 p.
    • 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
2/15/2010

References
  • Classification and Map Identifiers

    Cowardian Wetland Classification: Not applicable

    National Vegetation Classification Standard:
    Class Shrubland and Grassland
    Subclass Temperate and Boreal Shrubland and Grassland
    Formation Temperate Grassland, Meadow and Shrubland
    Division Vancouverian and Rocky Mountain Grassland and Shrubland
    Macrogroup Northern Rocky Mountain Lowland Grassland and Shrubland

    NatureServe Identifiers:
    Element Global ID 28658
    System Code CES306.822, Rocky Mountain Lower Montane-Foothill Shrubland

    ReGAP:
    5263: Rocky Mountain Lower Montane-Foothill Shrubland



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Citation for data on this website:
Rocky Mountain Lower Montane-Foothill Shrubland.  Montana Field Guide.  Retrieved on November 28, 2014, from http://FieldGuide.mt.gov/displayES_Detail.aspx?ES=5263
 
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