Interior PNW Douglas-fir Forest and Woodland
Global Name:
Central Rocky Mountain Dry Mixed Conifer Forest & Woodland
Global Rank:
G4G5
State Rank:
S4
(see reason below)
External Links
State Rank Reason
These forests are relatively common in western MT. Habitat has been impacted in the past and continues to be by the combination of fire suppression and increased fuel loads in conjunction with more recent increases in severe wildfires. Other threats currently appear to be limited in scope or severity, such that the habitat appears to be relatively secure.
General Description
This National Vegetation Classification Group is composed of montane coniferous forests dominated by Douglas-fir (Pseudotsuga menziesii) often with a Ponderosa Pine (Pinus ponderosa) component; these forests have an affinity to the Interior Pacific Northwest in terms of distribution and floristic affinities. As such, it occurs predominantly west of the Continental Divide in Montana, though some of the Associations contained within it also occur east of the Divide. This is a common and widespread group in western Montana. However, the distinction between this group and G215 Rocky Mtn Douglas-fir Forest, which occurs more on the eastside of the Continental Divide in Montana is not clearcut and additional review and refinement of the two groups is still needed.
Other seral conifer species typical of these stands include, Lodgepole Pine (Pinus contorta), Western White Pine (Pinus monticola), and Western Larch (Larix occidentalis). Grand Fir (Abies grandis), a fire-sensitive, shade-tolerant species has increased on many sites once dominated by Douglas-fir. These were historically maintained by low-severity wildfire. Understories may be dominated by shrubs or graminoids. A potential realignment of Associations with G215 is needed before a comprehensive summary of understory vegetation can be provided that better distinguishes between the two groups.
This group incorporates portions of the Rocky Mountain Dry-Mesic Montane Mixed Conifer Forest Ecological System and the Rocky Mountain Montane Douglas-fir Forest and Woodland.
Diagnostic Characteristics
Conifer Forest and Woodland; Montane Zone; Inland Pacific Northwest and Rocky Mtn Region
Typical Dominants: Douglas-fir (Pseudotsuga menziesii) with Ponderosa Pine (Pinus ponderosa) as a codominant.
Similar Systems
Range
In Montana, this group occurs primarily west of the Continental Divide where it may be found in all the major mountain ranges and major river drainages within this area. East of the Divide, it is found in more localized patches where it overlaps with G15.
In MT, G210 occurs within these Level III Ecoregions: 15 (Northern Rockies), 16 (Idaho Batholith), 17 (Middle Rockies), and 41 (Canadian Rockies).
In Montana, G210 occurs within these Major Land Resource Areas: 43A-Northern Rocky Mountains; 43B-Central Rocky Mountains, and 44A - Northern Rocky Mountain Valleys.
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, Deer Lodge, Flathead, Granite, Lake, Lewis and Clark, Lincoln, Mineral, Missoula, Pondera, Powell, Ravalli, Sanders, Teton
Based on 2025 land cover layer.
Spatial Pattern
Matrix
Environment
This group is associated with a submesic climate regime typical of the Inland Pacific Northwest. It is typified by warm, dry summers and cold winters. Annual precipitation ranges from 20-40 inches, with a maximum in winter or late spring. Winter snowpacks typically melt off in early spring at lower elevations. Elevations range from 2,000 to 6,700ft.
Vegetation
This montane coniferous forest group is dominated by Douglas-fir (Pseudotsuga menziesii), often with Ponderosa Pine (Pinus ponderosa), though pine is sometime absent from these sites. Other conifer species may occur in the tree canopy, including Western Larch (Larix occidentalis), Lodgepole Pine (Pinus contorta), and Western White Pine (Pinus monticola). Stands of this group often occur as large patches. Grand Fir (Abies grandis), a fire-sensitive, shade-tolerant species has increased on many sites once dominated by Douglas-fir (Pseudotsuga menziesii) and Ponderosa Pine (Pinus ponderosa), which were formerly maintained by low-severity wildfire. The floristic affinities of this group are allied with the maritime-influenced climate of the Interior Pacific Northwest.
Understories may be dominated by shrubs or graminoids. The Douglas-fir/pinegrass (Calamagrostis rubescens) type is the most ubiquitous association found within this group in Montana. A potential realignment of Associations with G215 is needed before a comprehensive summary of understory vegetation can be provided that better distinguishes between the two groups.
In Montana, this group is currently composed of 11 Associations in 2 Alliances. However, the relationship of this group to G215 requires further evaluation. At a minimum, several Associations within these groups need to be realigned. It may be better to combine these two groups into one group due to the large amount of geographic and floristic overlap.
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.Nb D337 Rocky Mountain Foothills and Montane Forest and Woodland
TT2.b3.Nb.3 M501 Central Rocky Mountain Montane Forest and Woodland
TT2.b3.Nb.3.b G210 Central Rocky Mountain Dry Mixed Conifer Forest and Woodland
A3392 Pseudotsuga menziesii - Pinus ponderosa Dry-mesic Central Rocky Mountain Forest and Woodland Alliance
CEGL000429 Pseudotsuga menziesii / Calamagrostis rubescens Woodland
CEGL000447 Pseudotsuga menziesii / Physocarpus malvaceus Forest
CEGL000459 Pseudotsuga menziesii / Symphoricarpos albus Forest
CEGL008730 Pseudotsuga menziesii / Symphoricarpos oreophilus Central Rockies Forest
A3395 Pseudotsuga menziesii - Pinus ponderosa Dry Central Rocky Mountain Woodland Alliance
CEGL000424 Pseudotsuga menziesii / Arctostaphylos uva-ursi Forest
CEGL000439 Pseudotsuga menziesii / Juniperus communis Forest
CEGL000440 Pseudotsuga menziesii / Juniperus osteosperma Forest
CEGL000900 Pseudotsuga menziesii / Festuca idahoensis Woodland
CEGL000901 Pseudotsuga menziesii / Festuca campestris Woodland
CEGL000908 Pseudotsuga menziesii / Pseudoroegneria spicata Woodland
CEGL008961 Pseudotsuga menziesii / Carex geyeri Central Rockies 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
Disturbances in these forests are primarily caused by fire and insects. Fire return intervals generally range from 20-45 years, although fire-free periods may be longer at more mesic or higher elevation sites (Steinberg 2002; U.S. Department of Agriculture 2012). The majority of fires are mixed-severity, although stand replacement and low-severity fires may also occur (U.S. Department of Agriculture 2012). Douglas-fir regenerates well following fire, with higher regeneration following low-severity burns (Harvey et al. 2013). After about 40 years, trees develop fire-resistant bark that promotes tolerance of low to moderate intensity surface fires (Steinberg 2002). In the absence of disturbance, Douglas-fir will continue to regenerate under shaded conditions, and becomes dominant in undisturbed stands.
Pre-settlement fire regimes may have been characterized by frequent, low intensity ground fires that maintained relatively open stands. Under present conditions, the fire regime is mixed severity and more variable, with stand-replacing fires more common, encouraging forest homogeneity. With vigorous fire suppression, longer fire-return intervals are now common, and multi-layered stands provide ladder fuels, making these forests more susceptible to high-intensity, stand-replacing fires. In some areas, these forests have been priorities for timber harvesting and grazing. An additional consequence of fire suppression has been the establishment of Douglas-fir in sagebrush steppe and grassland ecosystems in southwestern Montana. Historically, frequent fires confined Douglas-fir growth to particularly rocky or moist microsites. (Arno and Gruell 1986; Heyerdahl et al. 2006).
Fire additionally interacts with biotic disturbance dynamics in this group. The Douglas-fir bark beetle (Dendroctonus pseudotsugae) causes abundant damage, and fire-affected stands tend to be more vulnerable to attack (Negron et al. 1999; Hood et al. 2007; Six and Skov 2009). A study from southwestern Montana found that large trees with high levels of crown scorch in dense stands were most vulnerable to beetle attack post-fire (Hood et al. 2007). In some cases, post-fire beetle infestations may spread to nearby trees not injured by fire (DeNitto et al. 2000). Post-fire mortality may also occur as the result of Douglas-fir tussock moth (Orgyia pseudotsugata), western spruce budworm (Choristoneura occidentalis), and wood borers. Trees infected with Douglas-fir dwarf mistletoe (Arceuthobium douglasii) may be more susceptible to fire due to the accumulation of dense brooms that serve as ladder fuels (Steinberg 2002).
In recent years, these forests have been subjected to prolonged periods of drought, creating conditions where stands are susceptible to outbreaks of Douglas-fir tussock moth and Douglas-fir bark beetle. The combination of prolonged drought and fire suppression have also contributed to an increase in the intensity and duration of western spruce budworm epidemics, increased Douglas-fir bark beetle populations, and increased dwarf mistletoe infestation (Steinberg 2002). In addition to the effects of drought, disturbances such as snow breakage and windthrow may increase stand susceptibility to insect attack (Negron et al. 1999).
Management
In the absence of natural fire, periodic prescribed burns can be used to maintain this group. Low-severity burning decreases fuel loading, probability of stand-replacing fires, and increases available nutrients in the soil (Arno et al. 1995). Prescribed fire may additionally be useful for limiting invasion of Douglas-fir into sagebrush steppe and grassland ecosystems in southwestern Montana (Steinberg 2002; Heyerdahl et al. 2006). It may be important to consider the consequences of prescribed burning on stand susceptibility to Douglas-fir beetles, as beetles respond quickly to available resource pulses (i.e. fire damaged trees) following fire (Negron et al. 1999; Six and Skov 2009).
Restoration Considerations
Post-fire Douglas-fir forest restoration strategies will depend largely on the severity of the fire. Because these forests recover well following light to moderate intensity burns, restoration practices are generally not necessary. Recovery may be slow after large-scale stand-replacing fires, as seeds are wind-dispersed and rely on nearby stands to provide a seed source. Severely burned sites on steep slopes will require sediment retention and erosion control actions before and during restoration. When supplemental seeding or planting is necessitated, Douglas-fir establishment is best on mineral soil or thin organic seedbeds, and survival is greatest at relatively dry sites with partial shading (Steinberg 2002). Prescribed fire may be an additional valuable restoration strategy in stands with high levels of dwarf mistletoe. High severity burning controls Douglas-fir dwarf mistletoe by eliminating infected trees and promoting regeneration of uninfected individuals (Alexander and Hawksworth 1976). However, when utilizing prescribed burning as a restoration strategy, the effects of fire on local Douglas-fir beetle populations should be considered.
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
M.S. Reid and K.A. Schulz
Montana Version Authors
S. Mincemoyer
Version Date
12/4/2024
References
- Literature Cited AboveLegend:
View Online Publication
Alexander, M.E. and F.G. Hawksworth. 1976. Fire and dwarf mistletoes in North American coniferous forests. Journal of Forestry 74(7):446-449.- Amo, S.F., M.G. Harrington, C.E. Fiedler, and C.E. Carlson. 1995. Restoring fire-dependent ponderosa pine forests in western Montana. Restoration and Management Notes 13:32-36.
- Arno, S.F. and G.E. Guell. 1986. Douglas-fir encroachment into mountain grasslands in southwestern Montana. J. Range Management 39(3):272-276.
- DeNitto, G., B. Cramer, K. Gibson, B. Lockman, T. McConnell, L. Stipe, and J. Taylor. 2000. Survivability and deterioration of fire-injured trees in the northern rocky mountains: a review of the literature. The Bark Beetles, Fuels, and Fire Bibliography 1.
- Harvey, B.J., D.C. Donato, W.H. Romme, and M.G. Turner. 2013. Influence of recent bark beetle outbreak on fire severity and postfire tree regeneration in montane Douglas-fir forests. Ecology 94(11): 2475-2486.
- Heyerdahl, E.K., R.F. Miller, and R.A. Parsons. 2006. History of fire and Douglas-fir establishment in a savanna and sagebrush–grassland mosaic, southwestern Montana, USA. Forest Ecology and Management 230(1):107-118.
- Hood, S, B. Bentz, K. Gibson, K. Ryan, and G. DeNitto. 2007. Assessing post-fire Douglas-fir mortality and Douglas-fir beetle attacks in the northern Rocky Mountains. Gen. Tech. Rep. RMRS-GTR-199. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station. 31 p.
- Negron, J.F., W.C. Schaupp, K.E. Gibson, J. Anhold, D. Hansen, R. Their, and P. Mocettini. 1999. Estimating extent of mortality associated with the Douglas-fir beetle in the central and northern Rockies. Western Journal of Applied Forestry 14(3):121-127.
- Six, D.L. and K. Skov. 2009. Response of bark beetles and their natural enemies to fire and fire surrogate treatments in mixed-conifer forests in western Montana. Forest Ecology and Management 258(5):761-772.
- Steinberg, P. D. 2002. Pseudotsuga menziesii var. glauca. In: Fire Effects Information System, [Online}. U. S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory.
- U.S. Department of Agriculture, Forest Service, Missoula Fire Sciences Laboratory. 2012. Information from LANDFIRE on Fire Regimes of Northern Rocky Mounatin Montane Mixed-Conifer Communities. In: Fire Effects Information System, [Online]. U.S. Department
- Additional ReferencesLegend: View Online Publication
Do you know of a citation we're missing?- Arno, S. 1979. Forest regions of Montana. Research paper Int-218, USFS Intermountain and Range Experiment Station, Ogden, Utah.
- 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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