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Alpine Dwarf-Shrubland

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Provisional State Rank: S4
* (see reason below)

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State Rank Reason
Climate change is the major threat over the long term.
 

General Description

This system occurs above upper treeline throughout the Rocky Mountains and east into the mountain island ranges of central Montana. Elevation ranges from as low as 1,981 meters (6,500 feet) in northwestern Montana to 3,200 meters (10,500 feet) in southern Montana. The climate is very cold, with heavy snow accumulation and a very short growing season (60 to 90 days). This system occurs on level or concave glacial topography with late-lying snow and subirrigation from surrounding slopes. It can occur on all aspects, but is most common on north and east facing aspects. These sites are characterized as snow bed communities, where snow persists until mid or late summer, or occasionally, until fall. Soil temperatures remain colder than in the surrounding alpine meadows throughout the growing season. Soils are moist but well-drained, strongly acidic, and often with substantial peat layers. These dwarf shrublands are characterized by a semi-continuous layer of ericaceous dwarf-shrubs or dwarf willows which form a heath type ground cover less than 0.5 m (1.6 foot) in height. The ericaceous shrub community is dominated by western moss heather (Cassiope mertensiana), white arctic mountainheather (Cassiope tetragona), yellow mountain heath (Phyllodoce glanduliflora), pink mountain heath (Phyllodoce empetrifomis), and alpine bog laurel (Kalmia microphylla). Grouse whortleberry (Vaccinium scoparium), bilberry (Vaccinium myrtillus) or mountain huckleberry (Vaccinium membranaceum) are often found within the heath shrublands in northwestern Montana. The willow community forms localized thickets on level areas or on the perimeter of depressional areas and can be dominated by either mat forming or dwarf -shrub alpine willows (Salix spp.). The herbaceous understory is composed of a diversity of alpine sedges (Carex ssp.), rushes (Juncus spp.), woodrushes (Luzula spp.), alpine grasses and forbs.


Diagnostic Characteristics
alpine, patterned ground, glaciated, udic, acidic soils, alpine slopes, dwarf shrubland, very long disturbance interval

Similar Systems

Range
This system occurs above upper treeline throughout the Rocky Mountain ranges, and east into the mountain island ranges of central and south-central Montana. Elsewhere, this system ranges from the Canadian Rocky Mountains of British Columbia and Alberta south to northern New Mexico and the mountains of Utah and Nevada. It is found west from Montana throughout the mountains of Idaho, Oregon and the Cascade and Olympic Mountains of Washington.

Ecological System Distribution
Approximately 280 square kilometers are classified as Alpine Dwarf-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, CARBON, DEER LODGE, FLATHEAD, GALLATIN, GLACIER, GRANITE, LEWIS AND CLARK, LINCOLN, MADISON, MISSOULA, PARK, PONDERA, POWELL, RAVALLI, STILLWATER, SWEET GRASS, TETON

Spatial Pattern
Large patch

Environment
This system is found in areas of level or concave glacial topography with late-lying snow and subirrigation from surrounding alpine slopes. Elevation ranges from as low as 1,981 meters (6,500 feet) in northwestern Montana to 3,200 meters (10,500 feet) in southwestern Montana. Sites are characterized as snow bed communities, which form in concave, depressional areas that retain snow until mid to late summer. It can occur on all aspects but is most common on north and east facing aspects. Soil temperatures remain colder than in the surrounding alpine meadow throughout the growing season. Soils have become relatively stabilized in these sites, and are moist but well-drained, strongly acidic, and often with substantial peat layers. Vegetation in these areas is controlled by snow retention, wind desiccation, and a short growing season, usually only 60 to 90 days.

Vegetation

This system is composed of dwarf shrublands of ericaceous dwarf-shrubs or dwarf, alpine willows forming a low shrubland ground cover less than 0.5 meters (1.6 feet) in height. The ericaceous shrub community is dominated by western moss heather, white arctic mountainheather, yellow mountain heath, pink mountain, and alpine bog laurel. Grouse whortleberry, bilberry, or mountain huckleberry are often found within the heath shrublands, especially in northwestern Montana. Common graminoids and forbs include showy sedge (Carex spectabilis), shortstalk sedge (Carex podocarpa), Rocky Mountain sedge (Carex scopulorum), Hitchcock’s woodrush (Luzula glabrata var. hitchcockii) and Piper’s woodrush (Luzula piperi). Forbs such as alpine pussytoes (Antennaria species), arnica (Arnica species), Indian paintbrush (Castilleja species), glacier lily (Erythronium grandiflorum), alpine Saint John’s wort (Hypericum formosum), viviparous bistort (Polygonum viviparum) and Rocky Mountain groundsel (Packera cymbalarioides) are found within the heath-dominated shrubland.

Willow dominated communities form localized thickets on more level areas or around the perimeter of depressional areas. These depressional areas can have greater peat development. Dwarf, mat-forming species such as arctic willow (Salix arctica) and snow willow (Salix reticulata) are common associates. Other willow bed communities composed of shrubs that are less than .5 metrs (1.6 feet) tall include undergreen willow (Salix commutata), grayleaf willow (Salix glauca), plane leaf willow (Salix planifolia), and, in areas underlain by calcareous parent material, shortfruit willow (Salix brachycarpa) (Bamberg and Major, 1968). Sedges and rushes dominate in the depressional or level areas and are usually the last to emerge after snowmelt. These areas are species poor and are dominated by black sedge (Carex nigricans), Drummond’s rush (Juncus drummondii) and tufted hairgrass (Deschampsia cespitosa) or purple mountain hairgrass (Vahlodea atropurpurea). Sibbaldia (Sibbaldia procumbens), Ross’ avens (Geum rossii), and marsh marigold (Caltha leptosepala) often occur in openings in the peat (Cooper et al., 1997). Alpine dwarf shrublands occur as distinct patch types within Rocky Mountain Alpine Fell-Fields or adjacent to Rocky Mountain Alpine-Montane Wet Meadows or at the upper elevational limit of Rocky Mountain Subalpine Woodlands and Parklands.


Alliances and Associations
Alliances
  • () 
  • (A.1114) (Dwarf Bilberry, Whortleberry, Grouseberry) Dwarf-shrubland Alliance
  • (A.1096) Alpine Laurel Saturated Dwarf-shrubland Alliance
  • (A.1117) Arctic Willow Dwarf-shrubland Alliance
  • (A.1124) Arctic Willow Saturated Dwarf-shrubland Alliance
  • (A.1577) Eight-petal Mountain-avens Dwarf-shrub Herbaceous Alliance
  • (A.963) Grayleaf Willow Temporarily Flooded Shrubland Alliance
  • (A.1125) Net-vein Willow Saturated Dwarf-shrubland Alliance
  • (A.1083) Pink Mountain-heath Dwarf-shrubland Alliance
  • (A.1081) Western Moss Heather Dwarf-shrubland Alliance
  • (A.1089) Western Moss Heather Temporarily Flooded Dwarf-shrubland Alliance
  • (A.1576) White Mountain-avens Dwarf-shrub Herbaceous Alliance
  • (A.1084) Yellow Mountain-heath Dwarf-shrubland Alliance

Dynamic Processes
The fire disturbance interval is typically very long (500 years or greater) within this system. Historically, stand-replacing fires occur infrequently in adjacent associated subalpine woodlands (Arno, 1979). Lightning strikes can cause fire within these systems, although severity and spread is usually variable. Other disturbances include high elevation mining, heavy recreational use, and grazing.

Management
This system is especially fragile due to the extreme limited growing season and soil development. Species that occur in these systems are generally slow growing and decrease in cover and vigor in areas of trampling or grazing.

Restoration Considerations
Removal of disturbance is necessary before any kind of restoration can be considered. Natural recovery may occur over time.

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 Polar and High Montane Vegetation
    Subclass Temperate and Boreal Alpine Vegetation
    Formation Alpine Scrub, Forb Meadow and Grassland
    Division Western North America Alpine Scrub, Forb Meadow and Grassland
    Macrogroup Rocky Mountain Alpine Scrub, Forb Meadow and Grassland

    NatureServe Identifiers:
    Element Global ID 28646
    System Code CES306.810, Rocky Mountain Alpine Dwarf-Shrubland

    National Land Cover Dataset:
    52: Scrub/Shrub

    ReGAP:
    5207: Rocky Mountain Alpine Dwarf-Shrubland


  • Additional ReferencesLegend:   View WorldCat Record   View Online Publication
    Do you know of a citation we're missing?
    • Arno, S. F. 1980. Forest fire history in the northern Rockies. Journal of Forestry 78(8):460-465.
    • Bamberg, S. A., and J. Major. 1968. Ecology of the vegetation and soils associated with calcareous parent materials in three alpine regions of Montana. Ecological Monographs 38(2):127-167.
    • Cooper, Stephen V, Peter Lesica, and Deborah S. Page-Dumroese. Plant Community Classification for Alpine Vegetation on the Beaverhead National Forest, Montana. Ogden, UT (324 25th Street, Ogden 84401: U.S. Dept. of Agriculture, Forest Service, Intermountain Research Station, 1997. Print.


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Citation for data on this website:
Alpine Dwarf-Shrubland — Rocky Mountain Alpine Dwarf-Shrubland.  Montana Field Guide.  Retrieved on October 22, 2014, from http://FieldGuide.mt.gov/displayES_Detail.aspx?ES=5207
 
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