Whitebark Pine - Subalpine Larch Forest and Woodland
Global Name:
Central Rocky Mountain Whitebark Pine - Subalpine Larch Forest & Woodland
Global Rank:
G4G5
State Rank:
S3
(see reason below)
External Links
State Rank Reason
These habitats are widespread in the higher mountain ranges of the state though whitebark pine has decreased significantly due primarily to mortality from white pine blister rust. The rank reflects the combination of threats and population declines to whitebark pine but also that subalpine larch communities are included and have been more stable and have fewer threats.
General Description
This National Vegetation Classification Group is characterized by forests and woodlands dominated by Whitebark Pine (Pinus albicaulis) or Subalpine Larch (Larix lyallii), individually or in combination. Other conifers, primarily Subalpine Fir (Abies lasiocarpa) and Engelmann Spruce (Picea engelmannii) may be present, especially in Whitebark Pine stands. It occurs frequently on both sides of the Continental Divide in the subalpine zone of the higher mountain ranges and typically forms the highest elevation forested communities in many mountain ranges. Stands typically occur between elevations of 6,000 to 9,500ft. on mid to upper slopes, shoulder slopes, ridges, and exposed high-elevation benches on all aspects. Trees are often stunted and flagged as a result of harsh cold and wind at timberline. Stands in more protected sites or below timberline may reach 50ft or more in height. The understory is variable depending on substrates ranging from sparse on rockier sites to dense on more mesic sites and typically characterized by low-growing, ericaceous shrubs, graminoids and sparse forbs. Fire is infrequent in this group, though it is important in maintaining some stands and removing competition from more shade tolerant conifers. However, sparse canopies and rocky terrain limits the spread of fire at many sites.
This group is similar to the Rocky Mountain Subalpine Woodland and Parkland Ecological System.
Diagnostic Characteristics
Conifer Forest and Woodland; Rocky Mountains; Subalpine Zone, Timberline; Mixed Severity Fires.
Typical Dominants: Whitebark Pine (Pinus albicaulis), Subalpine Larch (Larix lyallii)
Similar Systems
Range
In Montana, this group occurs frequently on both sides of the Continental Divide in the subalpine zone of the higher mountain ranges. It often forms the highest elevation forested communities in many mountain ranges. It extends east to the Little Belt Mountains, the Crazy Mountains and the Beartooth Plateau where it forms extensive stands. Whitebark Pine occurs in the Sweetgrass Hills and the Big Snowy Mtns but does not appear to be abundant or extensive enough to form communities. Communities containing Subalpine Larch occur mostly west of the Continental Divide but can be found in limited stands east of the Divide in Glacier National Park and in the Bob Marshall Wilderness Complex. Further south it can be found as far east as the Flint Creek Range, the Pintlers and the Beaverhead (Big Hole) Mtns.
In MT, G223 occurs within these Level III Ecoregions: 15 (Northern Rockies), 16 (Idaho Batholith), 17 (Middle Rockies) and 41 (Canadian Rockies).
In Montana, G223 occurs within these Major Land Resource Areas: 43A-Northern Rocky Mountains, 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, Broadwater, Carbon, Cascade, Deer Lodge, Fergus, Flathead, Gallatin, Glacier, Golden Valley, Granite, Jefferson, Judith Basin, Lake, Lewis and Clark, Lincoln, Madison, Meagher, Mineral, Missoula, Park, Pondera, Powell, Ravalli, Sanders, Silver Bow, Stillwater, Sweet Grass, Teton, Toole, Wheatland
Based on 2025 land cover layer.
Spatial Pattern
Large Patch
Environment
This subalpine forest and woodland group typically occurs between elevations of 6,000 to 9,500ft. Stands occur on mid to upper slopes, shoulder slopes, ridges, and exposed high-elevation benches on all aspects. These sites are often subject to desiccating winds, heavy snowpack, and extreme diurnal temperate fluctuations. Substrates include a variety of igneous, metamorphic, and sedimentary geologic formations. Soils are well- to excessively drained and can include coarse sand, silt and clay loams. The climate is typically very cold and snowy in winter and relatively dry in summer. Yearly snow accumulations are typically greater than 6ft . Some sites have little snow accumulation because of high winds and sublimation. In this harsh, often windswept environment, trees are often stunted and flagged from damage associated with wind and blowing snow and ice crystals, especially at the upper elevations of the type. Where Subalpine Larch is dominant, soils are poorly developed and almost exclusively of fractured granitic or quartzite rocks which have not been previously colonized by other vascular plants. The majority of sites where Subalpine Larch occurs are in areas which experienced heavy alpine glaciation less than 12,000 years ago.
Vegetation
This group is characterized by forests and woodlands dominated by Whitebark Pine (Pinus albicaulis) or Subalpine Larch (Larix lyallii), individually or in combination. Other conifers, primarily Subalpine Fir (Abies lasiocarpa) and Engelmann Spruce (Picea engelmannii) may be present, especially in Whitebark Pine stands. Trees are often stunted and flagged as a result of harsh cold and wind at timberline. Stands in more protected sites or below timberline may reach 50ft or more in height. The understory is variable depending on substrates ranging from sparse on rockier sites to dense on more mesic sites and typically characterized by heaths and graminoids and sparse forbs. Shrubs and subshrubs common in these sites include Kinnikinnick (Arctostaphylos uva-ursi), Pink Mountain-heath (Phyllodoce empetriformis), Grouse Whortleberry (Vaccinium scoparium) and False Huckleberry (Menziesia ferruginea). The herbaceous layer is sparse under dense shrub canopies or may be dense where the shrub canopy is open or absent. Common species include Beargrass (Xerophyllum tenax), Ross’s Sedge (Carex rossii), Pinegrass (Calamagrostis rubescens), woodrush (Luzula hitchcockii), Mountain Arnica (Arnica latifolia) and Alpine Hawkweed (Hieracium gracile). Non-native species are generally absent or incidental in these high-elevation forests.
In Montana, this group is composed of 17 Associations grouped into 2 Alliances within the National Vegetation Classification, which likely covers the diversity of types within this group in the state.
National Vegetation Classification
Download the complete NVC hierarchy for Montana
TT2 B02 Temperate-Boreal Forest and Woodland
TT2.b S92 Cool Temperate Forest and Woodland
TT2.b3 F112 Temperate Continental Conifer Forest and Woodland
TT2.b3.Nd D336 Western Cordilleran Subalpine-High Montane Forest and Woodland
TT2.b3.Nd.2 M020 Rocky Mountain Subalpine-Upper Montane Forest and Woodland
TT2.b3.Nd.2.f G223 Central Rocky Mountain Whitebark Pine - Subalpine Larch Woodland
A0631 Larix lyallii Woodland Alliance
CEGL000521 Larix lyallii - Abies lasiocarpa Forest [Placeholder]
CEGL000623 Larix lyallii Woodland
CEGL000951 Larix lyallii / Vaccinium scoparium / Luzula glabrata Woodland
CEGL005884 Larix lyallii / Vaccinium membranaceum / Luzula glabrata Woodland
A3368 Pinus albicaulis Forest and Woodland Alliance
CEGL000128 Pinus albicaulis - Abies lasiocarpa Woodland
CEGL000129 Pinus albicaulis / Carex rossii Forest
CEGL000131 Pinus albicaulis / Vaccinium scoparium Forest
CEGL000752 Abies lasiocarpa - Pinus albicaulis / Vaccinium scoparium Woodland
CEGL000754 Pinus albicaulis - (Abies lasiocarpa) / Carex geyeri Woodland
CEGL000755 Pinus albicaulis / Festuca idahoensis Woodland
CEGL000756 Pinus albicaulis / Juniperus communis Woodland
CEGL000758 Pinus albicaulis / Luzula glabrata Woodland
CEGL005836 Pinus albicaulis - Abies lasiocarpa / Menziesia ferruginea / Xerophyllum tenax Woodland
CEGL005837 Pinus albicaulis - Abies lasiocarpa / Vaccinium membranaceum / Xerophyllum tenax Woodland
CEGL005838 Pinus albicaulis - Abies lasiocarpa / Vaccinium scoparium / Xerophyllum tenax Woodland
CEGL005839 Pinus albicaulis - Abies lasiocarpa / Vaccinium scoparium / Luzula glabrata Woodland
CEGL005840 Pinus albicaulis - (Picea engelmannii) / Dryas octopetala Woodland
*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
Whitebark Pine is a slow-growing, long-lived conifer that is common at higher elevations in the upper subalpine zone. It occurs as extensive forests or as a mosaic of tree islands. In lower subalpine forests, it is a seral species, establishing after a large disturbance such as stand-replacing fire, or it is restricted to dry, rocky ridges where it competes well with shade-tolerant tree species. Without disturbance, it will be overtopped in 100-120 years by faster growing, shade-tolerant species such as Abies lasiocarpa, Picea engelmannii, Pseudotsuga menziesii, and Tsuga mertensiana. Although crown fires and high-intensity surface fires kill Whitebark Pine, it tolerates low-intensity surface fires that will kill the shade-tolerant understory. Fire intervals range from 30-300 years.
Birds and small mammals often eat and cache the large, wingless pine seeds and are responsible for the dispersal of this species. Most important is the Clark's nutcracker, which can transport the seeds long distances and cache them on exposed windswept and burned-over sites. This results in the regeneration of pines in clumps from forgotten caches (Eyre 1980, Steel et al. 1983, Burns and Honkala 1990a, Schmidt and McDonald 1990).
Pests include the mountain pine beetle (Dendroctonus ponderosae), which has killed many mature trees in the past, during epidemics where populations of the beetle build up in lower elevation Pinus contorta stands, then move up into the Pinus albicaulis (Steel et al. 1983; Burns and Honkala 1990a; Schmidt and McDonald 1990). The exotic pathogen white pine blister rust (Cronartium ribicola) is attacking and killing Whitebark Pine trees in many parts of the interior northwestern U.S. It is especially destructive in more mesic habitats that favor infection of its alternate host Ribes spp (Currants and Gooseberries). Whitebark Pine is very susceptible to this disease and high rates of mortality have occurred across large portions of its range. (Steel et al. 1983; Burns and Honkala 1990a; Schmidt and McDonald 1990; Tomback et al. 2001).
Subalpine Larch is a very slow-growing, long-lived tree, with individuals attaining up to 1000 years in age (Richards 1981). It is generally intolerant of shade from other trees, but extreme environmental conditions limit competition. Reproduction is typically by seed and is most favorable on moist mineral soil. Seedling growth is initially very slow and accelerates after an extensive root system is established. Major disturbances to stands of this group are windthrow and snow avalanches. Lightning damage to individual trees is common, but sparse canopies and rocky terrain serve to limit the spread of fire.
Management
In the absence of natural fire, periodic low-severity prescribed burns can be implemented during late fall months to maintain, enhance, and restore these forests. Fire facilitates nutrient cycling and encourages whitebark pine dominance in stands where succession by subalpine fir and Engelmann spruce is occurring (Arno and Hoff 1989). Fire additionally creates open sites favorable to seed caching by Clark’s nutcrackers and exposes mineral soil seedbeds favored by whitebark pine and alpine larch. A long-term study in western Montana and eastern Idaho found that prescribed fire is likely most effective at restoring whitebark pine if burn sites are in close proximity to healthy whitebark stands, or if burning is followed by planting of rust-resistant nursery stock (Keane and Parsons 2010). When selecting seed sources for supplemental planting, seed transfer guidelines should be followed to avoid maladaptation to site specific conditions (Bower and Aitken 2008).
Restoration Considerations
Restoration strategies within Whitebark Pine stands will in part depend on degree of blister rust infection. Small-scale prescribed burning during late fall after several hard frosts is recommended to prevent succession by subalpine fir and facilitate whitebark pine regeneration by providing open sites on exposed mineral soils suitable for nutcracker seed caching and seedling establishment (Fryer 2002). Blister rust damage reduces cone production and nutcracker seed caching (McKinney and Tomback 2007). When blister rust infection within a region is severe, post-burn supplemental planting with genetically rust-resistant nursery stock may be necessary (Keane and Parsons 2010). Similarly, large scale mountain pine beetle outbreaks may necessitate supplemental planting if regeneration is limited or blister-rust infection of surviving individuals is severe. When outplanting rust-resistant nursery stock is necessary, success can be improved by reducing seedling competition with overstory trees or understory grasses and sedges, and planting seedlings in microsites with favorable growth conditions, including on the leeward side of rocks and stumps (McCaughey et al. 2009).
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
Amphibians
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
M.E. Hall and M.S. Reid 2013
Montana Version Authors
S. Mincemoyer, T. Luna, M. Hart, L. Vance
Version Date
12/4/2024
References
- Literature Cited AboveLegend:
View Online Publication- Arno, S.F. and R.J. Hoff. Silvics of whitebark pine (Pinus albicaulis). 1989. General Technical Report INT-253. Ogden, UT. USDA, Forest Service, Intermountain Research Station. 11pp.
Bower, A.D. and S.N. Aitken. 2008. Ecological genetics and seed transfer guidelines for Pinus albicaulis (Pinaceae). American Journal of Botany 95(1):66-76.- Burns, R. M., and B. H. Honkala, technical coordinators. 1990a. Silvics of North America: Volume 1. Conifers. USDA Forest Service. Agriculture Handbook 654. Washington, DC. 675 pp.
- Eyre, F.H. (ed). 1980. Forest cover types of the United States and Canada. Society of American Foresters, Washington, DC. 148 pp.
- Fryer, J.L. 2002. Pinus albicaulis. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory.
- Keane, R.E. and R.A. Parsons. 2010. Restoring whitebark pine forests of the northern Rocky Mountains, USA. Ecological Restoration 28(1):56-70.
- McCaughey, W., G.L. Scott,and K.L. Izlar. 2009. Technical note: whitebark pine planting guidelines. Western Journal of Applied Forestry 24(3):163-166.
- McKinney, S.T. and D.F. Tomback. 2007. The influence of white pine blister rust on seed dispersal in whitebark pine. Canadian Journal of Forest Research 37(6);1044-1057.
- Richards, J. H. 1981. Ecophysiology of a deciduous timberline tree: Larix lyallii Parl. Ph.D. thesis, University of Alberta, Edmonton. 228 pp.
- Schmidt, W. C., and K. J. McDonald, compilers. 1990. Proceedings-Symposium on whitebark pine ecosystems: Ecology and management of a high-mountain resource. March 29-31 1989, Bozeman, MT. USDA Forest Service General Technical Report INT-270. Intermountain Research Station, Ogden, UT. 386 pp.
- Steele, R.W., S.V. Cooper, D.M. Ondov, D.W. Roberts, and R.D. Pfister. 1983. Forest habitat types of eastern Idaho - western Wyoming. USDA Forest Service General Technical Report INT-144. Intermountain Forest and Range Experiment Station, Ogden, UT. 122 pp.
- Tomback, D. F., S. F. Arno, and R. E. Keane, editors. 2001. Whitebark pine communities: Ecology and restoration. Island Press. Washington, DC. 440 pp.
- Additional ReferencesLegend: 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.
- Arno, S.F., and J.R. Habeck. 1972. Ecology of alpine larch (Larix lyallii Parlatore) in the Pacific Northwest. Ecological Monographs 42(4):417-450.
- Bockino, N.K.and D.B. Tinker. 2012. Interactions of white pine blister rust and mountain pine beetle in whitebark pine ecosystems in the southern Greater Yellowstone Area. Natural Areas Journal 32(1):31-40.
- Callaway, R.M. 1998. Competition and facilitation on elevation gradients in subalpine forests of the northern Rocky Mountains, USA. Oikos 561-573.
- Habeck, R. J. 1991. Larix lyallii. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory.
- Klasner, Frederick L., and Daniel B. Fagre. 2002. "A Half Century of Change in Alpine Treeline Patterns at Glacier National Park, Montana, U.S.A.". Arctic, Antarctic, and Alpine Research. 34 (1): 49-56.
- McCaughey, W.W. 1990. Biotic and microsite factors affecting Pinus albicaulis establishment and survival. Ph.D. Dissertation. Bozeman, MT: Montana State University. 78 p.
- McCaughey, W.W. and D.F. Tomback. 2001. The natural regeneration process. pp105-120. In: Whitebark pine communities: ecology and restoration. Washington D.C.: Island Press.
- Pfister, R. D., B. L. Kovalchik, S. F. Arno, and R. C. Presby. 1977. Forest habitat types of Montana. USDA Forest Service. General Technical Report INT-34. Intermountain Forest and Range Experiment Station, Ogden, UT. 174 pp.
- Smith, C.M., B. Shepherd, C. Gillies,and J. Stuart-Smith. 2012. Changes in blister rust infection and mortality in whitebark pine over time. Canadian journal of forest research 43(1):90-96.
- Smith-Mckenna, E.K., L.M. Resler, D.F. Tomback, H. Zhang, and G.P. Malanson. 2013. Topographic influences on the distribution of white pine blister rust in Pinus albicaulis treeline communities. Ecoscience. 20:(3): 215-229.
- Tomback, D.F. 2005. The impact of seed dispersal by Clark’s nutcracker on whitebark pine: multi-scale perspective on a high mountain mutualism. pp. 181-201. In: Mountain Ecosystems. Springer Berlin Heidelberg.
- Tomback, D.F., K.G. Chipman, L.M. Resler, E.K. Smith-McKenna, and C.M. Smith. 2014. Relative abundance and functional role of whitebark pine at treeline in the Northern Rocky Mountains. Arctic, Antarctic, and Alpine Research 46(2):407-418.
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