Dry Spruce-fir Forest
Global Name:
Rocky Mountain Subalpine Dry-Mesic Spruce - Fir Forest
Global Rank:
G4G5
State Rank:
S4S5
(see reason below)
External Links
State Rank Reason
Relatively common and widespread habitat with few, pervasive threats and trends that have been relatively stable or only experienced minor declines in condition and/or extent.
General Description
This National Vegetation Classification Group is composed of forests dominated by Engelmann Spruce and Subalpine Fir, either in mixed stands or individually. They occur frequently on both sides of the Continental Divide in the upper montane and subalpine zones. This group occurs at the drier end of the Spruce-fir forest type and site characteristics and the understory vegetation should reflect that in relation to G218 Mesic Spruce-Fir. Other conifers are often present in these stands, typical species include Lodgepole Pine, Douglas-fir or Whitebark Pine. The forest understory may be composed of low shrubs, graminoids and/or forbs. Composition varies widely by geography, site characteristics and association. In some stands the understory will be depauperate and mosses may be prevalent.
Dry to mesic spruce-fir dominated forests occur as low as 3,000 feet west of the Continental Divide, and up to 9,500 feet east of the Continental Divide, particularly in southwestern Montana. Some occurrences are found in locations with cold-air drainage or ponding, or where snowpacks lingers late into the summer, such as north-facing slopes and high-elevation ravines. They can extend down in elevation below the subalpine zone in places where cold-air ponding occurs, especially on north and east aspects. Spruce-fir forests are found on gentle to very steep mountain slopes, high-elevation ridge tops and upper slopes, plateau-like surfaces, basins, alluvial terraces, well-drained benches, and inactive stream terraces. Soils are derived from a variety of parent materials, and are usually rocky or gravelly with good aeration and drainage.
The drier Spruce-fir forests of this group are especially common on steep slopes at upper elevations throughout the eastern Rocky Mountains, whereas the more mesic stands of G218 form substantial cover west of the Continental Divide in the Flathead, Lolo, Bitterroot and Kootenai river drainages.
This group is equivalent to the Rocky Mountain Subalpine Dry-Mesic Spruce-Fir Forest and Woodland Ecological System.
Diagnostic Characteristics
Subalpine Fir (Abies lasiocarpa), Engelmann Spruce (Picea engelmannii) Dominated; Xeric Conifer Forest and Woodlands; Upper Montane and Subalpine Zones; Moderate to Dense Canopies; Moderate to Long Fire Return Intervals, Mixed Severity or Stand Replacing Fires.
Similar Systems
Range
In Montana, this Group occurs frequently on both sides of the Continental Divide in the upper montane and subalpine zones. It extends east to the Bears Paw Mountains where it occurs in very limited amounts, the Highwoods Mtns, the Snowy Mtns, and the Pryor and Bighorn Mtns.
In MT, G219 occurs within these Level III Ecoregions: 15 (Northern Rockies), 16 (Idaho Batholith), 17 (Middle Rockies) and 41 (Canadian Rockies).
In Montana, G219 occurs within these Major Land Resource Areas: 43A-Northern Rocky Mountains, 43B - Central Rocky Mountains, 44A - Northern Rocky Mountain Valleys, and 46 - Northern and Central Rocky Mountain Foothills.
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, Big Horn, Broadwater, Carbon, Cascade, Chouteau, Deer Lodge, Fergus, Flathead, Gallatin, Glacier, Golden Valley, Granite, Hill, Jefferson, Judith Basin, Lake, Lewis and Clark, Liberty, 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-Matrix
Environment
This group occurs at relatively low to high elevations west of the Continental Divide and mid to high elevations east of the Divide throughout the mountains and island ranges of north-central and west-central Montana. These forests are found on gentle to very steep mountain slopes, high-elevation ridge tops and upper slopes, plateau-like surfaces, basins, alluvial terraces, well-drained benches, and inactive stream terraces. Occurrences are also found in locations with cold-air drainage or ponding, or where snowpacks linger late into the summer, such as north-facing slopes and high-elevation ravines. They can extend down in elevation below the subalpine zone in places where cold-air ponding occurs, especially on north and east aspects. Dry to mesic spruce-fir dominated forests occur as low as 3,000 feet west of the Continental Divide, and up to 9,500 feet east of the Continental Divide, particularly in southwestern Montana. Soils are derived from a variety of parent materials, and are usually rocky or gravelly with good aeration and drainage.
Engelmann spruce and subalpine fir forests comprise a substantial part of subalpine forests in Montana, including the island ranges of north-central and west-central Montana and southern Montana. In the driest mountain ranges east of the Continental Divide (such as the Bull Mountains, Snowy Mountains, Pryor Mountains, and Dillon area), these forests are restricted to cool exposures, usually on north and east facing aspects. The drier Spruce-fir forests of this group are especially common on steep slopes at upper elevations throughout the eastern Rocky Mountains, whereas the more mesic stands of G218 form substantial cover west of the Continental Divide in the Flathead, Lolo, Bitterroot and Kootenai river drainages.
Vegetation
These forests are dominated by Engelmann Spruce and Subalpine Fir, either in mixed stands or individually. Other conifers are often present and typically may include Lodgepole Pine, Douglas-fir or Whitebark Pine, with Lodgepole Pine more typical of earlier successional stands, Douglas-fir at lower elevations and Whitebark Pine at higher elevations. This group occurs at the drier end of the Spruce-fir forest type and site characteristics and the understory vegetation should reflect that in relation to G218 Mesic Spruce-Fir.
The forest understory may be composed of low shrubs, graminoids and/or forbs. Composition varies widely by geography, site characteristics and Association. Common shrubs in these drier Spruce-fir forests include Grouse Whortleberry (Vaccinium scoparium), Dwarf Huckleberry (Vaccinium cespitosum), Common Juniper (Juniperus communis), Ninebark (Physocarpus malvaceus), Canada Buffaloberry (Shepherdia canadensis), Spiraea (Spiraea betulifolia), Creeping Oregon-grape (Berberis repens) and Snowberry (Symphoricarpos albus). Common forbs include Arnica (Arnica cordifolia, Arnica latifolia), Clematis (C. columbiana, C. occidentalis), Fragrant Bedstraw (Galium triflorum) and Twinflower (Linnaea borealis). Graminoids are generally few with Pinegrass (Calamagrostis rubescens), Geyer’s sedge (Carex geyeri), and Ross’ sedge (Carex rossii) the common components on these drier sites. Moss may be common in some depauperate understories. Non-native species are typically absent or uncommon in these communities.
In Montana, this group is represented by 15 Associations grouped into 3 Alliances within the National Vegetation Classification, though 2 Alliances only have 1 Association each. These likely represent the diversity of types within this group in Montana.
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.b G219 Rocky Mountain Subalpine Dry-Mesic Spruce - Fir Forest
A3643 Abies lasiocarpa - Picea engelmannii Rocky Mountain Dry-Mesic Forest Alliance
CEGL000298 Abies lasiocarpa - Picea engelmannii / Arnica cordifolia Forest
CEGL000299 Abies lasiocarpa - Picea engelmannii / Arnica latifolia Forest
CEGL000301 Abies lasiocarpa - Picea engelmannii / Calamagrostis rubescens Forest
CEGL000304 Abies lasiocarpa - Picea engelmannii / Carex geyeri Forest
CEGL000306 Abies lasiocarpa / Clematis columbiana var. columbiana Forest
CEGL000337 Abies lasiocarpa - Picea engelmannii / Symphoricarpos albus Forest
CEGL000344 Abies lasiocarpa - Picea engelmannii / Vaccinium scoparium Forest
CEGL000368 Picea engelmannii / Hypnum revolutum Forest
CEGL000381 Picea engelmannii / Vaccinium scoparium Forest
CEGL000919 Abies lasiocarpa - Picea engelmannii / Juniperus communis Woodland
CEGL002676 Picea engelmannii / Physocarpus malvaceus Forest
CEGL005918 Abies lasiocarpa - Picea engelmannii / Vaccinium cespitosum / Clintonia uniflora Forest
CEGL005925 Picea engelmannii / Juniperus communis Forest
A3644 Abies lasiocarpa - Picea engelmannii Dry-Mesic Scree and Talus Woodland Alliance
CEGL000925 Abies lasiocarpa Scree Woodland
A3645 Abies lasiocarpa - Populus tremuloides Rocky Mountain Dry-Mesic Forest Alliance
CEGL000529 Populus tremuloides - Abies lasiocarpa / Shepherdia canadensis Forest
*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
Major disturbances include occasional blowdown, insect outbreaks (30-50 years), and fire. Fire return intervals average approximately 130 years and are either mixed severity or stand replacing (U.S. Department of Agriculture 2012). Fires in this group are generally more frequent and less intense than those in G218 Mesic Spruce-Fir Forest and Woodland. Both subalpine fir and Engelmann spruce are highly susceptible to fire, in part due to their shallow roots, thin bark, and dense stand growth habits (Alexander and Shepperd 1990; Uchytil 1991). Following fire, spruce is more successful at establishing on mineral soils. Subalpine fir, in contrast, is better at establishing in the shade and on organic substrates. Post-fire, subalpine fir establishment may be immediate if nearby seed sources exist and seral lodgepole pine is not present. In forests undisturbed by fire or subjected to spruce budworm attacks, subalpine fir assumes greater dominance. Over a period of 500 years, subalpine fir will largely replace spruce on most of these sites.
Insects and disease can play a major role in the successional direction of these forests. Throughout Montana, subalpine fir and spruce are affected by western spruce budworm (Choristoneura occidentalis) attacks. The spruce beetle (Dendroctonus rufipennis) also causes extensive damage to spruce in this group. Severe wind events that cause extensive blowdown are often followed by spruce beetle outbreaks, as downed trees provide an abundant food supply and are favored by the beetles (Lindemann and Barker 2001). Other disturbances that cause an abundance of downed material, including landslides and avalanches, may also contribute to increases in beetle populations within a region (Jenkins et al. 2014). When outbreak conditions occur, or when downed material is unavailable, spruce beetles will also attack live trees, favoring large size classes and overmature individuals (Alexander and Shepperd 1990). Beetle outbreaks have implications for watershed function, wildlife habitat, recreation, and stand species composition (Jenkins et al. 2014).
Historically, spruce beetle outbreaks have been related to drought conditions as drought weakens spruce resistance mechanisms to beetle attack (DeRose and Long 2012; Jenkins et al. 2014). Drought has additionally been found to have lag effects on mortality for spruce, subalpine fir and lodgepole pine, with drought having the most substantial and long-lasting effects on subalpine fir, and the smallest impact on lodgepole pine (Bigler et al. 2007). Large stands of these subalpine forests can be killed following several years of drought or unusually mild winters.
Spruce broom rust (Chrysomyxa arctostaphyli) also occurs in this group causing deformation, and increased vulnerability to windbreak (Alexander and Shepperd 1990). Subalpine fir is additionally affected by western balsam bark beetle (Dryocoetes confuses), balsam wooly adelgid (Adelges piceae), and the fir engraver beetle (Scolytus ventralis). Root and wood rots also affect the dominant species in this group by weakening their defenses to insect attack and increasing vulnerability to windfall (Jenkins et al. 2014).
Management
In the absence of natural fire, periodic prescribed burns can be used to maintain this group. Maintaining historic fire return intervals may decrease stand susceptibility to spruce beetle outbreak (Bebi et al 2003; Kulakowski and Veblen 2006). Old stands have a greater abundance of downed material and overmature individuals that are vulnerable to attack. Moderate to severe fires change the age structure of a stand thereby decreasing susceptibility to future beetle attack (Kulakowski and Veblen 2006).
All species in this group are vulnerable to windthrow. Mechanical thinning for silvicultural or fire risk reduction purposes should therefore consider stand blowdown as a potential result of thinning treatment. Risk of windfall increases in stands with shallow soils and poor drainage, high degree of root and wood rot, and old, dense stand structure (Alexander and Shepperd 1990). Alternatively, thinning may be useful to promote natural regeneration and reduce abundance of overmature individuals in a stand, altering stand age structure, and thereby decreasing susceptibility to future spruce beetle outbreaks. However, logging residue may contribute to beetle population increases, and downed woody material may therefore need to be removed from the site to reduce potential for future beetle outbreak (Jenkins et al. 2014).
Restoration Considerations
Post-fire restoration strategies will be largely dependent on the severity of the fire. Because lightly burned areas recover quite quickly from fire, reseeding is usually not necessary if an intact, native understory was present before the fire. Early successional stages may be dominated by fireweed, arnica, aster, pearly everlasting (Anaphalis margaritacea), mountain hollyhock (Iliamina rivularis) and other forbs, and small amounts of forest graminoids. Both dominant species are good seed producers and are capable of regenerating well following fire. Spruce is capable of regenerating well on bare mineral soils if adequate moisture is present during the first two years of growth. Subalpine fir colonizes sites with both mineral soil and those with some organic matter. At the higher elevation occurrences of this group, seedling survival may be greater where duff seedbeds are present as they protect seedlings from harsh climatic conditions (Uchytil 1991).
Large, prescribed, stand-replacement fires are not recommended in areas where spruce is in severe decline. Small-scale prescribed burning during late fall after several hard frosts can facilitate regeneration and increase stand heterogeneity in terms of age structure and species composition, thereby decreasing susceptibility to insect outbreaks (Jenkins et al. 2014). In some cases, nursery stock may be used to expedite regeneration on severely burned areas if seed rain from adjacent stands is not likely to occur, or if bare mineral soil following severe insect outbreak is limited (Jenkins et al. 2014). When supplemental planting is required, cold, moist stratification is necessary for germination of subalpine fir and spruce (Uchytil 1991). Success of seedling establishment will be greatest when spring and early summer conditions are relatively moist and late summer drought is not intense (Alexander and Shepperd 1990).
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
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
K.A. Schulz 2013
Montana Version Authors
S. Mincemoyer, L. Vance, T. Luna, M. Hart
Version Date
12/4/2024
References
- Literature Cited AboveLegend:
View Online Publication
Alexander, R.R. and W.D. Shepperd. 1990. Picea engelmannii Parry ex Engelm. Silvics of North America 1:187-203.- Bebi, P., D. Kulakowski, and T.T. Veblen. 2003. Interactions between fire and spruce beetles in a subalpine Rocky Mountain forest landscape. Ecology 84(2):362-371.
- Bigler, C., D.G. Gavin, C. Gunning, and T.T. Veblen. 2007. Drought induces lagged tree mortality in a subalpine forest in the Rocky Mountains. Oikos 116(12):1983-1994.
- DeRose, R.J. and J.N. Long. 2012. Factors influencing the spatial and temporal dynamics of Engelmann spruce mortality during a spruce beetle outbreak on the Markagunt Plateau, Utah. Forest Science 58(1): 1-14.
- Jenkins, M.J., E.G. Hebertson, and A.S. Munson. 2014. Spruce beetle biology, ecology and management in the Rocky Mountains: an addendum to spruce beetle in the rockies. Forests 5(1):21-71.
- Kulakowski, D. and T.T. Veblen. 2006. The effect of fires on susceptibility of subalpine forests to a 19th century spruce beetle outbreak in western Colorado. Canadian Journal of Forest Research 36(11):2974-2982.
- Lindemann, J.D. and W.L. Baker. 2001. Attributes of blowdown patches from a severe wind event in the Southern Rocky Mountains, USA. Landscape Ecology 16(4):313-325.
- U.S. Department of Agriculture, Forest Service, Missoula Fire Sciences Laboratory. 2012. Information from LANDFIRE on Fire Regimes of Rocky Mounatin Subalpine Mixed-Conifer Communities. In: Fire Effects Information System, [Online]. U.S. Department of Agr
- Uchytil, R.J. 1991. Abies lasiocarpa. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory.
- 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.
- 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.
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