Rocky Mountain Ponderosa Pine Forest and Woodland
Global Name:
Central Rocky Mountain Ponderosa Pine Forest & Woodland
Global Rank:
G4G5
State Rank:
S4S5
(see reason below)
External Links
State Rank Reason
A common and widespread type that is negatively impacted by invasive weeds and to a lesser extent by development in some of its lower elevation habitat.
General Description
This National Vegetation Classification Group is composed of Ponderosa Pine Forests and Woodlands. It occurs on warm, dry, exposed sites in the foothills and lower montane zone of the Rocky Mountains in west-central and central Montana, at the ecotone between lower elevation grasslands or shrublands and more mesic coniferous forests. It is an extensive, lower elevation forest type with small to large patch sizes depending on topography. Elevations range from 3,500-5,500 feet, with the higher elevation examples occurring in central Montana. Occurrences are found on all slopes and aspects. Habitats are characteristically an open forest with a grassy understory. East of the Continental Divide, it is most widespread around Helena and Lewistown, although it occurs throughout mountain ranges as far east as the Little Rocky and Bearpaw Mountains. Ponderosa pine (Pinus ponderosa) is the dominant conifer. Douglas-fir (Pseudotsuga menziesii) and western larch (Larix occidentalis) may be present in the tree canopy particularly west of the Continental Divide. In central Montana, limber pine (Pinus flexilis) is occasionally present. Understory vegetation is typically grasses and forbs that resprout following low to moderate intensity surface fires. Prolonged drought, beetle kill and invasion of non-native species are rapidly changing the dynamics of these habitats.
This group includes the Rocky Mountain Ponderosa Pine Woodland and Savanna Ecological System and a portion of the Rocky Mountain Foothill Woodland-Steppe Transition Ecological System.
Diagnostic Characteristics
Ponderosa Pine (Pinus ponderosa); Xeric Conifer Forest and Woodland; Tree Cover generally from 10-50%, Rocky Mtn Foothills and Montane Zone; Soils with an A Horizon <10 cm; Low Intensity, Frequent Fire Regime.
Similar Systems
Range
In Montana, this group occurs in the foothills and montane zone in mountainous areas on both sides of the Continental Divide, excluding most of southwest Montana and along the Rocky Mtn Front where Ponderosa Pine is largely absent. East of the Continental Divide in central Montana, it occurs along the lower slopes of several of the isolated mountain ranges, including the Bears Paw and Little Rockies.
In MT, G213 occurs within these Level III Ecoregions: 15 (Northern Rockies), 16 (Idaho Batholith), 17 (Middle Rockies), and 41 (Canadian Rockies).
In Montana, G213 occurs within these Major Land Resource Areas: 43A - Northern Rocky Mountains, 43B - Central Rocky Mountains, 44A - Northern Rocky Mountain Valleys, 44B - Central Rocky Mountain Valleys, 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, Blaine, 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, Musselshell, Park, Phillips, Pondera, Powell, Ravalli, Sanders, Silver Bow, Stillwater, Sweet Grass, Teton, Toole, Wheatland
Based on 2025 land cover layer.
Spatial Pattern
Matrix
Environment
In western and central Montana, this group forms a belt on warm, dry, exposed sites between lower elevation grasslands and Douglas-fir (Pseudotsuga menziesii) forests. Elevations range from 3,500-5,500 feet (Pfister etal 1977). Stands can occur at higher elevations in central Montana. It is generally found on gravelly soils with good aeration and drainage and a neutral to slightly acidic pH.
Vegetation
Ponderosa pine (Pinus ponderosa) is the dominant conifer. Douglas-fir (Pseudotsuga menziesii) and Western Larch (Larix occidentalis) may be present in the tree canopy west of the Continental Divide and the former is also present east of the Divide in areas such as the foothills around Helena. In central Montana, limber pine may be a component of some stands. The understory may have a shrub component though habitats are mostly dominated by grasses. Shrubs such as antelope bitterbrush, snowberry, serviceberry (Amelanchier alnifolia), bearberry (Arctostaphylos uva-ursi), common juniper (Juniperus communis) and skunkbush occur in forests on benchlands and rocky slopes in the central portion of the state. Total shrub cover in these sites is relatively low. Understory vegetation is more typically perennial grasses and forbs. These more open stands support grasses such as bluebunch wheatgrass (Elymus spicatus), Idaho fescue (Festuca idahoensis), rough fescue (Festuca campestris), prairie junegrass (Koeleria macrantha) and needle and thread (Stipa comata), as well as dryland sedges like threadleaf sedge (Carex filifolia) and sun sedge (Carex inops ssp. heliophila). Common forbs include yarrow (Achillea millefolium), rosy pussytoes (Antennaria rosea), arrowleaf balsamroot (Balsamorhiza sagittata), Indian blanket flower (Gaillardia aristata), and silky lupine (Lupinus sericeus). Invasive species such as Cheatgrass (Bromus tectorum) and Spotted Knapweed (Centaurea stoebe) are prevalent at some sites.
In Montana, this Group is represented by 2 Alliances and 9 Associations. These are generally well-described and likely represent the diversity of types on the landscape.
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.d G213 Central Rocky Mountain Ponderosa Pine Forest and Woodland
A4708 Pinus ponderosa Central Rockies Mesic Shrubby Woodland Alliance
CEGL000189 Pinus ponderosa / Physocarpus malvaceus Forest
CEGL000203 Pinus ponderosa / Symphoricarpos albus Forest
CEGL005648 Pinus ponderosa / Purshia tridentata Central Rocky Mountain Woodland
CEGL005841 Pinus ponderosa / Vaccinium cespitosum Woodland
A4709 Pinus ponderosa Central Rocky Mountain Dry Open Woodland Alliance
CEGL000185 Pinus ponderosa / Festuca campestris Woodland
CEGL000195 Pinus ponderosa / Purshia tridentata / Festuca idahoensis Woodland
CEGL000197 Pinus ponderosa / Purshia tridentata / Pseudoroegneria spicata Woodland
CEGL000865 Pinus ponderosa / Pseudoroegneria spicata Woodland
CEGL008959 Pinus ponderosa / Festuca idahoensis Central Rockies 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
Under natural conditions, ponderosa pine woodlands and grasslands are maintained by frequent surface fires (Arno 1980), and in western Montana low-severity fires occur at mean return intervals of 15 to 23 years (Smith and Fischer 1997). In comparison to the Great Plains Ponderosa Pine Woodlands in central and eastern Montana, this group experiences a larger percentage of mixed-severity fires (U.S. Department of Agriculture 2012). The threat of stand-replacing fires is high in areas where periodic fires have been suppressed. A study at the Sawmill Resource Natural Area in the Bitterroot National Forest found an average fire return interval of 13 years prior to the initiation of systematic fire suppression policies. The thick bark and open crown structure of ponderosa pines allows them to withstand fire, a necessity in this group to control competition and allow for successful regeneration. In the absence of fire, forest density increases, and less fire tolerant species like Douglas-fir become more common (Gayton et al. 2006). Increased forest density also leads to increased incidence of high severity fires and greater susceptibility to insect attack (Jenkins etal. 2014; Habeck 1992).
Many biotic disturbances affect this group. Seedlings and saplings can be deformed by shoot borers (Eucosma sonomana) and tip moths (Rhyacionia bushnelli), and defoliation can occur as a result of insects like the pine butterfly (Neophasia menapia). The insects that cause the most extensive mortality in this group are of the genus Dendroctonus, and include the western pine beetle (Dendroctonus brevicomis) and the mountain pine beetle (Dendroctonus ponderosae) (Graham and Jain 2005; Habeck 1992). Bark beetles generally occur at endemic levels in this group. However, in recent years, prolonged summer drought, milder winters, and exclusion of low severity fires resulting in increased stand density have contributed to greater susceptibility to and increasing severity of bark beetle outbreaks (Kolb etal. 2007). Fire may also decrease tree defenses to beetle attack immediately post-fire, resulting in increased vulnerability to insect attack (Davis etal. 2012). Additionally, pathogens like dwarf mistletoe (Arceuthobium campylopodum) influence ponderosa pine growth rates and interact with the effects of beetle attacks to increase downed woody surface fuels (Klutsch et al., 2014). Ponderosa pine mortality is high in many areas of Montana, especially in the west-central area of the state. Increased incidence of beetle outbreaks in ponderosa pine stands can have ecosystem-level effects including changes to carbon cycling (Kurz et al., 2008), hydrology (Bearup et al., 2014; Mikkelson et al., 2013), and fuel structure and flammability (Hicke et al. 2012; Jolly et al. 2012).
Grazing by domestic livestock may reduce bunchgrasses, and in cases of intensive overgrazing, cheatgrass (Bromus tectorum) may be dominant in the understory. Disturbances including wind, snow, and ice result in decreased stand density and provide canopy openings that allow for regeneration (Graham and Jain 2005).
Management
In the absence of natural fire, periodic prescribed burning in late fall, selective thinning, and reduction of ladder and basal fuels to prevent crown fires can be used to maintain and restore this group to similar pre-settlement conditions. Habeck (1992) suggests prescribed burning at intervals of 20 to 25 years to maintain ponderosa pine dominance and nutrient cycling within this group. Prescribed burning may increase long-term mortality of old growth ponderosa pine, particularly when combined with increased drought stress (Kolb et al. 2007). Thinning of understory trees and removal of ladder fuels and accumulated organic matter from the base of large trees may be necessary to protect old growth from mortality during prescribed burns (Kolb et al. 2007). Mechanical thinning has the added benefit of decreasing stand susceptibility to mountain pine beetle attack and dwarf mistletoe as outbreaks are generally associated with high stand densities (Jenkins et al. 2014; Klutsch et al. 2014).
Periodic burning is used to expose mineral soils, provide nutrient availability, reduce competition, stimulate native grass and forb production, increase basal diameter growth of overstory ponderosa pine, and provide favorable seedbeds. Management actions that increase basal diameter growth may also favor resistance to bark beetle attacks (Kolb et al. 2007). In some cases, especially on sites heavily infested with cheatgrass, frequent prescribed burning may stimulate greater cheatgrass cover following fire, especially if the burn does not eliminate the seed bank. Increasing time between prescribed fires may inhibit cheatgrass by increasing surface fuels (both herbaceous and litter) which directly inhibit establishment. Postfire cheatgrass dominance has been shown to be most strongly controlled by the pre-fire seed bank, soil moisture, fire intensity, soil nitrogen, and duration of direct sunlight (Keeley and McGinnis 2007). Excessive grazing can lead to the loss of the most common perennial grasses and increased abundance of exotic grasses. Cheatgrass establishment in low-elevation ponderosa pine and Douglas-fir forests can be enhanced by disturbance that opens the understory, removes litter, or both (Mack and Pyke 1983). Prolific seed production also contributes to the competitive advantage of this grass over native grasses and associated perennial forbs (Aguirre and Johnson 1991).
Restoration Considerations
Post-fire restoration strategies will depend largely on fire severity. Because fire creates favorable seedbeds for seedling establishment, lightly burned areas recover quite quickly from fire and restoration practices are generally not necessary. In cases where severe, stand-replacing fires have occurred, reseeding or replanting efforts may be necessary. When supplemental seeding or planting is necessitated, germination and seedling survival are enhanced by a period of cold stratification and relatively moist conditions (Habeck 1992). To ensure successful establishment, repeated browsing by deer or trampling by livestock should be minimized (Habeck 1992).
Wildfire severity and frequency are expected to increase in this group threatening old growth ponderosa pine stands that historically experienced frequent low-severity fires. In the absence of natural fire, restoration treatments such as mechanical thinning or prescribed burning reduce fuels that accumulate in the understory leading to high intensity, stand replacing fires. Additional benefits of thinning include a reduction of competition stress on old trees, which may in turn reduce mortality associated with drought and mountain pine beetles (Jenkins et al. 2014; Kolb et al. 2007).
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, K.A. Schulz and M. Manning
Montana Version Authors
S. Mincemoyer
Version Date
12/4/2024
References
- Literature Cited AboveLegend:
View Online Publication- Aguirre, Lucrecia, and Douglas A. Johnson. 1991. "Influence of Temperature and Cheatgrass Competition on Seedling Development of Two Bunchgrasses". Journal of Range Management. 44 (4): 347-354.
Arno, S. F. 1980. Forest fire history in the northern Rockies. Journal of Forestry 78(8):460-465.- Bearup, L.A., R.M. Maxwell, D.W. Clow, and J.E. McCray. 2014. Hydrological effects of forest transpiration loss in bark beetle-impacted watersheds. Nature Climate Change 4(6):481-486.
- Davis, R.S., S. Hood, and B.J. Bentz. 2012. Fire-injured ponderosa pine provide a pulsed resource for bark beetles. Canadian Journal of Forest Research 42:2022-2036.
- Gayton DV, Weber MH, Harrington M, Heyerdahl DK, Sutherland BB, Hall C, Hartman M, Peterson L, Merrel C. 2006. Fire history of a western Montana ponderosa pine grassland: A pilot study. In: Speer JH, editor. Experiential learning and exploratory research: The 13th annual North American dendroecological fieldweek (NADEF). Prof. Paper Ser. No. 23. Terre Haute, IN: Department of Geography, Geology, and Anthropology, Indiana State University; p 30-6.
- Graham, R.T. and T.B. Jain. 2005. Ponderosa pine ecosystems. pp. 1-32. In: Proceedings of the Symposium on Ponderosa Pine: Issues, Trends, and Management, Gen. Tech. Rep. PSW-GTR-198. Albany CA: Pacific Southwest Research Station, Forest Service, US Department of Agriculture, Klamath Falls, OR.
- Habeck, R.J. 1992. Pinus ponderosa var. ponderosa. In: Fire Effects Information System. Missoula, MT: USDA Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory. 1 p.
- Hicke, J.A., M.C. Johnson, J.L. Hayes, and H.K. Preisler. 2012. Effects of bark beetle-caused tree mortality on wildfire. Forest Ecology and Management 271:81-90.
- Jenkins, M.J., J.B. Runyon, C.J. Fettig, W.G. Page, and B.J. Bentz. 2014. Interactions among the mountain pine beetle, fires, and fuels. Forest Science 60:489-501.
- Jolly, W.M., R.A. Parsons, A.M. Hadlow, G.M. Cohn, S.S. McAllister, J.B. Popp, and J.F. Negron. 2012. Relationships between moisture, chemistry, and ignition of Pinus contorta needles during the early stages of mountain pine beetle attack. Forest Ecology and Management 269:52-59.
- Keeley, J. E., and T. W. Mcginnis. 2007. "Impact of Prescribed Fire and Other Factors on Cheatgrass Persistence in a Sierra Nevada Ponderosa Pine Forest". International Journal of Wildland Fire. 16 (1): 96-106.
- Klutsch, J.G., R.D. Beam, W.R. Jacobi, and J.F. Negrón. 2014. Bark beetles and dwarf mistletoe interact to alter downed woody material, canopy structure, and stand characteristics in northern Colorado ponderosa pine. Forest Ecology and Management 315:63-71.
- Kolb, T.E.,J.K. Agee, P.Z. Fule, N.G. McDowell, K. Pearson, A.Sala, and R.H. Waring. 2007. Perpetuating old ponderosa pine. Forest Ecology and Management 249(3):141-157.
- Kurz, W.A., C.C. Dymond, G. Stinson, G.J. Rampley, E.T. Neilson, A.L. Carroll, and L. Safranyik. 2008. Mountain pine beetle and forest carbon feedback to climate change. Nature 452(7190):987-990.
- Mack, Richard N., and David A. Pyke. 1983. "The Demography of Bromus Tectorum: Variation in Time and Space". The Journal of Ecology. 71 (1): 69-93.
- Mikkelson, K.M., L.A. Bearup, R.M. Maxwell, J D. Stednick, J.E. McCray, and J.O. Sharp. 2013. Bark beetle infestation impacts on nutrient cycling, water quality and interdependent hydrological effects. Biogeochemistry 115(1-3):1-21.
- 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, J. K. and W. C. Fischer. 1997. Fire ecology of the forest habitat types of northern Idaho. Gen. Tech. Rep. INT-GTR-363. USDA Forest Service, Ogden, UT.
- U.S. Department of Agriculture, Forest Service, Missoula Fire Sciences Laboratory. 2012. Information from LANDFIRE on Fire Regimes of Northern Rocky Mountain Ponderosa Pine Communities. In: Fire Effects Information System. Missoula, MT: USDA Forest Servic
- Web Search Engines for Articles on "Central Rocky Mountain Ponderosa Pine Forest & Woodland"
