Alpine Dwarf-Shrubland and Krummholz
Global Name:
Rocky Mountain-Sierran Alpine Dwarf-shrubland & Krummholz
Global Rank:
G4G5
State Rank:
S4
(see reason below)
External Links
State Rank Reason
This alpine group occurs in all the higher mountain ranges. They are primarily threatened by increased temperatures and changes in precipitation patterns and amounts, specifically decreases in winter snowpack, though they are relatively common and widespread.
General Description
This National Vegetation Classification Group occurs in the alpine zone and near the treeline in the upper subalpine zone in most of the higher elevation mountain ranges of Montana. The vegetation in this group is generally dominated or composed of a semi-continuous layer of low-growing shrubs including dwarf shrubs and subshrubs as well as krummholz communities. The elevations of these sites range from as low as 6,000 feet in northwestern Montana to 10,500 feet in southwestern Montana. As this group encompasses a variety of communities, site factors such as topographic position, slope, aspect, moisture conditions, parent material and soil characteristics are variable. Communities may be dominated by heath-like, ericaceous, dwarf-shrubs, others by subshrubs in fellfield or turflike conditions, by krummholz communities or rarely by other short-statured shrubs.
Sites dominated by Avens (Dryas) are typical of exposed, drier fellfields on ridges and saddles, while those dominated by dwarf willows vary from fellfield to turf-like communities. Mountain heather and heath communities often occur on level or concave glacial topography with late-lying snow and subirrigation from surrounding alpine slopes. The low shrub communities may form a dense, heath type ground cover less than 0.5 meters (1.6 feet) in height, communities dominated by dwarf-shrubs in fellfield-like habitats or as patches of low-growing shrubs. Some communities within this group are very similar to G314 - Alpine Turf and Fellfields except that they are dominated by dwarf shrubs instead of herbaceous species.
This group is equivalent to the Alpine Dwarf-Shrubland Ecological System as well as krummholz communities included in the Rocky Mountain Subalpine Woodland and Parkland, and the Spruce-Fir Forest and Woodland Ecological Systems.
Diagnostic Characteristics
Alpine Zone; Vegetation Cover >15%; Dwarf Shrubs, Subshrubs, Krummholz; Short Growing Season; Timberline; Fellfield, Turf and Snowbed Communities.
Similar Systems
Range
This group occurs in the higher elevation mountain ranges in Montana that have vegetated, alpine areas above treeline, including the island mountain ranges of central and south-central Montana.
In Montana, G316 is confined to areas within or immediately adjacent to Level IV Ecoregions 15h (High Northern Rockies), 16h (High Idaho Batholith), 17h (Middle Rockies Alpine Zone) and 41b Canadian Rockies Crestal Alpine-Subalpine Zone.
In Montana, G316 occurs within these Major Land Resource Areas: 43A-Northern Rocky Mountains and 43B-Central Rocky Mountains.
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, Carbon, Deer Lodge, Flathead, Gallatin, Glacier, Granite, Lake, Lewis and Clark, Lincoln, Madison, Meagher, Missoula, Park, Pondera, Powell, Ravalli, Silver Bow, Stillwater, Sweet Grass, Teton
Based on 2025 land cover layer.
Spatial Pattern
Small Patch and Large Patch
Environment
This group occurs in the alpine zone and along the treeline in the upper subalpine zone on various topography depending on the specific vegetation community. The elevation ranges from as low as 6,000 feet in northwestern Montana to 10,500 feet in southwestern Montana. The climate is very cold, with heavy snow accumulation and a very short growing season (60 to 90 days). As this group encompasses a variety of communities, site factors such as topographic position, slope, aspect, moisture conditions, parent material and soil characteristics are variable. Sites dominated by Avens (Dryas) are typical of exposed, drier fellfields on ridges and saddles, while those dominated by dwarf willows vary from fellfield to turf-like communities. Mountain heather and heath communities often occur on level or concave glacial topography with late-lying snow and subirrigation from surrounding alpine slopes. These sites are often characterized as snowbed communities, which form in concave, depressional areas that retain snow until mid to late summer and can occur on all aspects but are most common on north and east-facing aspects. Here, the soil temperatures remain colder throughout the growing season than on surrounding slopes and aspects. Soils have become relatively stabilized in these sites and are moist but well-drained and often acidic. Krummholz can occur on a variety of sites near timberline on relatively level to steep slopes.
Vegetation
The vegetation in this group is often composed of a semi-continuous layer of low-growing shrubs including dwarf shrubs and subshrubs as well as krummholz communities. The low shrub communities may take the form of a dense, heath type ground cover less than 0.5 meter (1.6 feet) in height, communities dominated by dwarf-shrubs in fellfield-like habitats, or as patches of low-growing shrubs on alpine slopes. The drier sites are similar to fellfield communities but have a relative dominance of dwarf shrubs. Some windswept and drier sites that are fellfield-like may be dominated by or have a relatively high coverage of Eight-petal Mountain-avens (Dryas hookeriana). The dwarf willows, Arctic willow (Salix arctica) and Net-veined Willow (Salix reticulata) are the relative dominants in dry to mesic sites that are similar to turf and fellfield communities of G314. The ericaceous heaths or mountain heathers (Cassiope mertensiana, Cassiope tetragona, Phyllodoce empetriformis, Phyllodoce glanduliflora) form heath type ground covers or patches in areas near timberline to areas higher in the alpine. Other shrubs that may be found as components of this group include Kinnikinnick (Arctostaphylos uva-ursi) on dry fellfield-like sites, Shrubby Cinquefoil (Dasiphora fruticosa, syn. Potentilla fruticosa), Alpine Bog Laurel (Kalmia microphylla) on mesic sites, Ribes montigenum, Salix vestita, and Grouse Whortleberry (Vaccinium scoparium).
In contrast to the low shrub dominated communities, the Krummholz communities within this group are dominated by stunted trees at timberline, formed by the harsh climate at these high elevations. Communities of this type form a mosaic of dense patches of matted, dwarfed, evergreen conifer trees usually less than 6 feet (2 meters) tall, occasionally with scattered, short, upright trees among the mats. In Montana, Subalpine Fir (Abies lasiocarpa), Engelmann Spruce (Picea engelmannii), and Whitebark Pine (Pinus albicaulis) are the primary krummholz-forming species.
Various alpine forbs and graminoids occur within these communities as scattered individuals or forming patches in a mosaic with the low shrub and krummholz communities. Frequent species include Showy Sedge (Carex spectabilis), Shortstalk Sedge (Carex podocarpa), Rocky Mountain Sedge (Carex scopulorum), Carex nigricans, 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), Luetkea pectinata, Luzula piperi, Oreostemma alpigenum, Pedicularis spp., Polemonium viscosum, Polygonum bistortoides, Polygonum viviparum, Sibbaldia procumbens and Rocky Mountain Groundsel (Packera cymbalarioides). Additional floristic information may be found in: Bamberg (1961), Bamberg and Major (1968), Cooper et al. (1997), and Billings (2000).
In Montana, this group is represented by 12 Associations grouped into 5 Alliances. These habitats have been well documented and this likely covers all the types expected to occur within this group in the state.
National Vegetation Classification
Download the complete NVC hierarchy for Montana
TT6 B06 Polar and Alpine
TT6.b S64 Temperate-Polar Alpine and Tundra
TT6.b2 F128 Temperate Alpine Grassland and Shrubland
TT6.b2.Nb D043 Western North American Alpine Tundra
TT6.b2.Nb.1 M099 Rocky Mountain-Sierran Alpine Tundra
TT6.b2.Nb.1.a G316 Rocky Mountain-Sierran Alpine Dwarf-shrubland and Krummholz
A3175 Ribes cereum - Ribes montigenum - Dasiphora fruticosa Alpine Shrubland Alliance
CEGL005833 Dasiphora fruticosa / Artemisia michauxiana Alpine Shrub Meadow
A3176 Salix arctica - Salix nivalis - Salix reticulata Alpine Dwarf-shrubland Alliance
CEGL001431 Salix arctica - (Salix petrophila, Salix nivalis) / Polygonum bistortoides Dwarf-shrubland
CEGL001435 Salix reticulata / Caltha leptosepala Dwarf-shrubland
CEGL005878 Salix arctica / Carex nigricans Dwarf-shrubland
A3177 Phyllodoce empetriformis - Phyllodoce glanduliflora / Sibbaldia procumbens Alpine Snowbed Dwarf-shrubland Alliance
CEGL001405 Phyllodoce empetriformis / Antennaria lanata Dwarf-shrubland
CEGL005877 Phyllodoce glanduliflora / Sibbaldia procumbens Dwarf-shrubland
A3178 Dryas integrifolia - Dryas octopetala - Arctostaphylos uva-ursi Rocky Mountain Fell-field Dwarf-shrubland Alliance
CEGL001890 Dryas integrifolia - Carex spp. Alpine Dwarf-shrub Meadow
CEGL001892 Dryas octopetala - Carex rupestris Alpine Dwarf-shrub Meadow
CEGL001893 Dryas octopetala - Carex spp. Alpine Dwarf-shrub Meadow
CEGL001894 Dryas octopetala - Polygonum viviparum Alpine Dwarf-shrub Meadow
CEGL005832 Arctostaphylos uva-ursi / Solidago multiradiata Dwarf-shrubland
A3640 Abies lasiocarpa - Picea engelmannii - Pinus flexilis Dry-Mesic Rocky Mountain Krummholz Alliance
CEGL000985 Abies lasiocarpa - Picea engelmannii Krummholz
*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 fire disturbance interval is typically very long within these communities. Historically, stand-replacing fires occur infrequently in adjacent subalpine woodlands (Arno 1979). Lightning strikes can cause fire within these communities, although severity and spread are usually limited.
Management
This system is especially fragile due to the very limited growing season and limited soil development. Species that occur in these systems are generally slow growing and decrease in cover and vigor in areas of trampling.
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
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
K.A. Schulz 2015
Montana Version Authors
S. Mincemoyer, L. Vance, T. Luna
Version Date
11/25/2024
References
- Literature Cited AboveLegend:
View Online Publication
Bamberg, S. A. 1961. Plant ecology of alpine tundra area in Montana and adjacent Wyoming. Unpublished dissertation, University of Colorado, Boulder. 163 pp.- 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.
- Billings, W. D. 2000. Alpine vegetation of North America. Pages 537-572 in: M. G. Barbour and W. D. Billings, editors. North American terrestrial vegetation. Second edition. Cambridge University Press, New York. 434 pp.
- Cooper, Stephen V., Peter Lesica, and Deborah S. Page-Dumroese. 1995. 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.
- Additional ReferencesLegend: View Online Publication
Do you know of a citation we're missing?- Pojar J., and A. MacKinnon. 2013. Alpine Plants of the Northwest: Wyoming to Alaska. Lone Pine Publishing. Edmonton, AB, Canada. 527pp.
- Zwinger, A. H., and B. E. Willard. 1996. Land above the trees: A guide to American alpine tundra. Johnson Books, Boulder, CO. 425 pp.
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