Alpine Bedrock and Scree
Global Name:
Rocky Mountain & Sierran Alpine Bedrock & Scree
Global Rank:
G4G5
State Rank:
S5
(see reason below)
External Links
State Rank Reason
These high elevation, rock-dominated and sparsely-vegetated habitats are relatively common and stable.
General Description
This National Vegetation Classification Group consists of exposed rock and rubble with very little vascular plant cover, occurring at or above the upper treeline in the mountains of western and central Montana. It is dominated by barren and sparsely vegetated alpine substrates, including bedrock outcrops, and talus and scree slopes occurring on upper mountain slopes, ridges and summits. Sparse cover of forbs, grasses, low shrubs and krummholz may be present with total vascular plant cover generally less than 10%, occasionally up to 25%. The high coverage of exposed rock limits the potential for additional vascular plant growth. Lichen-dominated communities covering the rock substrate are common and may greatly exceed 25% cover in some areas. The lower elevational limit for the alpine zone varies with latitude and aspect, ranging from about 8,000-9,500 feet in the southern part of the state to 6,000-7,000 feet in northwest Montana. Exposure to desiccating winds, rocky and sometimes unstable substrates, and a short growing season limit vascular plant growth. Unstable scree and talus, isolated boulder pockets and exposed bedrock constitute the majority of the surface cover. This group may occur as small patches intermingled with other alpine vegetation or as large discreet patches. In some areas it may transition seamlessly into G565 Rocky Mountain Cliff, Scree & Rock Outcrops Group below the upper treeline.
This group is equivalent to the Alpine Bedrock and Scree Ecological System.
Diagnostic Characteristics
Alpine; Treeline; Talus and Scree; Rock Outcrops; Alpine Slopes; Shallow, Patchy Soils; Less than 25% Vascular Plant Cover.
This Group can be distinguished from other alpine types by the sparse vegetation (often <10%) and high coverage of rock. It is separated from G565 (Rocky Mtn Cliff, Scree and Rock Outcrop) primarily by occurring at or above timberline and by representation of species found primarily in alpine habitats.
Similar Systems
Range
This group occurs in all the higher elevation mountain ranges in Montana that have some area above treeline.
In Montana, G571 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, G571 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, Fergus, Flathead, Gallatin, Glacier, Granite, Lake, Lewis and Clark, Lincoln, Madison, Meagher, Mineral, Missoula, Park, Pondera, Powell, Ravalli, Sanders, Silver Bow, Stillwater, Sweet Grass, Teton, Wheatland
Based on 2025 land cover layer.
Spatial Pattern
Large Patch
Environment
This group occurs above treeline in the alpine zone which starts at about 9,000 feet in the southern part of the state to as low as 6,000 feet in northwest Montana. It is composed of barren and sparsely vegetated alpine substrates, including bedrock outcrops, and talus and scree slopes, occurring on upper mountain slopes, ridges and summits. Igneous, metamorphic and/or sedimentary rocks alone or in combination may form the substrate of this type. It may occur on all aspects and slopes though is more common on moderate to steep slopes. Exposure to desiccating winds, rocky and sometimes unstable substrates, heavy snow loads, and a short growing season limit vascular plant growth. Steep, wind-scoured, talus and scree fields and exposed bedrock are often blown free of snow during winter, exposing plants to severe environmental conditions.
Soil development is very limited, and soils are usually very shallow, patchy, and gravelly or rocky. The limited soils can be either acidic or calcareous depending upon the local parent material. Organic matter is typically only found in very limited quantities in pockets among boulders, or in fractures or crevices. This group is characterized by a very cold climate and high winds during winter, and by high winds, and high UV radiation during the summer months. South and west-facing slopes may experience relatively high, daytime, surface temperatures during the summer. Annual precipitation in these alpine environments typically ranges from 30-70 inches with significant amounts of that falling as snow for more than half the year.
Vegetation
Plant cover in this alpine community is often less than 10% with exposed, unstable scree, talus and bedrock constituting the remainder of cover. Sparse cover of forbs, grasses, low shrubs and krummholz may be present with total vascular plant cover less than 25% due to the high cover of exposed rock. Most scree and bedrock inhabiting plants are highly adapted to this harsh environment and occur as singular plants among the exposed rocks or in bedrock fractures. These species are typically cushioned, matted or succulent, or grow as rosettes, often with thick leaf cuticles or a dense cover of hairs. Vascular plants growing on loose substrates typically have either an extensive, shallow root and rhizome system or a large taproot that anchors the plant.
Forbs occur singly or in small patches among the exposed talus and scree and in fractures of the bedrock or the leeside of bedrock where organic matter has accumulated. Forb species occurring in these habitats are many and vary across the state. In northwestern Montana, common forbs include, Common Yarrow (Achillea millefolium), Penstemon ellipticus, Phacelia species, Polemonium viscosum, Alpine Springbeauty (Claytonia megarhiza), Sandworts (Minuartia species), Cut-leaf Daisy (Erigeron compositus), Draba species, Oxytropis borealis, Oxytropis sericea, Senecio canus, Arnica alpina, Moss Campion (Silene acaulis), Spotted Saxifrage (Saxifraga bronchialis), Buckwheat (Eriogonum ovalifolium), Alpine Forget-me-not (Myosotis alpestris) and Eurybia sibirica. Shrubs and subshrubs such as Mountain-avens (Dryas hookeriana), Shrubby Cinquefoil (Dasiphora fruticosa) and Rock Willow (Salix vestita) may be present. In southwestern Montana, common forbs include Common Yarrow (Achillea millefolium), Lanceleaf Stonecrop (Sedum lanceolatum), Draba species, Fleabanes (Erigeron species), Potentilla species, and Alpine Smelowskia (Smelowskia calycina). Several species of ferns may also occur in protected microsites within this habitat across the state.
Graminoid cover is usually very low and often occurs within small patches and mats of forbs or woody species. Common species vary somewhat by geography but include Carex albonigra, Carex elynoides, Carex phaeocephala, Carex nardina, Carex ruprestris, Carex scirpoidea, Luzula spicata, Juncus drummondii, Parry’s rush (Juncus parryi), Idaho Fescue (Festuca idahoenisis), Poa alpina, and Trisetum spicatum. (Cooper et al. 1999; Cooper etal 1997).
Crustose and foliose lichen cover may be high (sometimes greater than 50%) on certain types of exposed talus and bedrock. Common lichen genera include Rhizocarpon, Xanthoria, Lecidea, and Umbilicaria species. Mosses are typically found in bedrock fractures and the leeside of bedrock slabs and chutes below the summits, especially on the north and east facing aspects. Several northern Rocky Mountain endemic species and Montana Species of Concern inhabit these alpine communities.
Currently only two Alliances and four Associations within the National Vegetation Classification are described and attributed with occurring in MT. Additional plant communities probably occur within this Group in MT, either undocumented or undescribed, or not currently attributed to MT.
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.c G571 Rocky Mountain and Sierran Alpine Bedrock and Scree
A4021 Rocky Mountain Alpine Sparse Herb Bedrock and Scree Alliance
CEGL005867 Carex spectabilis - Arnica x diversifolia Alpine Meadow
CEGL005900 Athyrium americanum - Cryptogramma acrostichoides Alpine Sparse Vegetation
CEGL005902 Saxifraga bronchialis Scree Slope Alpine Sparse Vegetation
CEGL005903 Saxifraga mertensiana Alpine Cliff Crevice
A4022 Rocky Mountain Alpine Nonvascular Bedrock and Scree Alliance
*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
High winds and desiccation, heavy snow loads, short growing seasons, and unstable slopes and surfaces are the dominant processes in this alpine environment.
Management
Extremely limited growing seasons, limited soil development and often poor access into these habitats limit potential uses and impacts.
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
Invertebrates
- 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- Cooper, S.V., C. Jean, and B.L. Heidel. 1999. Plant associations and related botanical inventory of the Beaverhead Mountains Section, Montana. Unpublished report to the Bureau of Land Management. Montana Natural Heritage Program, Helena. 235 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.
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