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Rocky Mountain Foothill Limber Pine - Juniper Woodland

Provisional State Rank: S5

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General Description

This ecological system occurs in foothill and lower montane zones in the northern Rocky Mountains and island mountain ranges of Montana and on escarpments extending out to the western Great Plains grasslands. Elevation ranges from 1,219 to 2,286 meters (4,000-7,500 feet), occasionally higher in southwestern Montana. At higher elevations, it is limited to sites with thin soils on rock outcrops. Some of the most ecologically interesting examples occur along and within the mountains of the Rocky Mountain Front where it occurs most commonly on west and north facing aspects. At lower elevations, it can occur on all aspects and on relatively level terrain. Fire is infrequent and spotty because rocky substrates inhibit growth of the continuous canopy that would be needed to spread. This system occurs on sites that are characterized by extreme winter weather and droughty summer conditions. It is typically dominated by limber pine (Pinus flexilis) or Rocky Mountain juniper (Juniperus scopulorum). This systemis usually found below continuous forests of Douglas-fir (Pseudotsuga menziesii), or rarely, ponderosa pine (Pinus ponderosa) or lodgepole pine (Pinus contorta) in the foothills. Rocky Mountain juniper stands often occur in complex transitional zones or grow on exposed or severe sites within other forest systems. These juniper stands can exhibit a savanna-like character in southwestern Montana. In the system as a whole, because sites are so marginal for tree growth, limber pine mortality from abiotic and biotic stresses may be high. East of the Continental Divide, limber pine can occur at the upper tree line, with whitebark pine (Pinus albicaulis) in Glacier National Park and the Sweetgrass Hills. The climtate characteristic of these systems is marked by a relatively small amount of precipitation, with the wettest months during the growing season, very low humidity, and wide annual and diurnal temperature ranges. Winter conditions may be very cold but relatively dry, and often include rapid fluctuations in temperature associated with chinook winds. In Montana, limber pine and Rocky Mountain juniper stands are found mainly on calcareous substrates. Soils have a high rock component (generally over 50% cover) and are coarse- to fine-textured, often gravelly. Slopes are moderately steep to steep.


Diagnostic Characteristics

Forest and woodland, aridic, sandy, shallow soils, organic A horizon less than 10 cm, Pinus flexilis, Juniperus scopulorum


Range
This system occurs in foothill and lower montane zones in the northern Rocky Mountain Front and foothills, within the island ranges, and on escarpments extending out into the western Great Plains. This system is well represented in the Gravelly Range and Beaverhead Range, and the greater Yellowstone ecosystem and the Pryor Range in the southern portion of the state. It ranges from southern Alberta to central Colorado and east into North and South Dakota.

Ecological System Distribution
Approximately 721 square kilometers are classified as Rocky Mountain Foothill Limber Pine - Juniper Woodland in the 2016 Montana Land Cover layers.  Grid on map is based on USGS 7.5 minute quadrangle map boundaries.



Montana Counties of Occurrence
Beaverhead, Big Horn, Blaine, Broadwater, Carbon, Carter, Cascade, Chouteau, Custer, Dawson, Deer Lodge, Fallon, Fergus, Flathead, Gallatin, Glacier, Golden Valley, Granite, Hill, Jefferson, Judith Basin, Lewis and Clark, Liberty, Madison, Mccone, Meagher, Musselshell, Park, Phillips, Pondera, Powder River, Powell, Prairie, Ravalli, Rosebud, Sanders, Silver Bow, Stillwater, Sweet Grass, Teton, Toole, Valley, Wheatland, Wibaux, Yellowstone

Spatial Pattern
Large patch

Environment

The systems is usually found below continuous forests of Douglas-fir (Pseudotsuga menziesii) or lodgepole pine (Pinus contorta) in the foothills,and can occur in large stands well within the zone of continuous forests in the northern Rocky Mountains. Along the Northern Rocky Mountain Front, this system is found on west and north facing aspects in the foothills and within the mountains. At lower elevations, it can occur on all aspects and on relatively level terrain. Rocky Mountain juniper stands are often found in complex transitional zones or growing on exposed or severe sites within other forest systems. Climate is characterized by a relatively small amount of precipitation, with the wettest months during the growing season, very low humidity, and wide annual and diurnal temperature ranges. Winter conditions may be very cold but relatively dry, and often include rapid fluctuations in temperature associated with chinook winds.

In Montana, this system occurs grows mainly on limestone substrates, where roots follow the pattern of fractured and weathered rock (Burns and Honkala, 1990). Soils have a high rock component (typically over 50% cover) and are coarse- to fine-textured, often gravelly and calcareous. Soils are generally poorly developed, shallow, have low moisture holding capacity and are easily erodable, so in some occurrences, little topsoil is present. Although the system can be seen on gently rolling terrain, limestone cliffs, and exposed bluffs, it is most often found on rocky ridges and steep rocky slopes, and can survive in extremely windswept areas at both lower and upper tree line. Slopes are typically moderately steep to steep. Elevation ranges from 1,219-2,286 meters (4,000-7,500 feet) (Pfister et al, 1977). In the Beaverhead Mountain range, it occurs at higher elevations (Cooper et al, 1999).


Vegetation

Vegetation is characterized by an open-tree canopy or patchy woodland that is dominated by either limber pine or Rocky Mountain juniper. In the Pryor Mountains Utah juniper (Juniperus osteosperma) is sometimes seen at its northernmost extent within this system. Douglas-fir regularly occurs, but ponderosa pine and lodgepole pine are comparatively rare within these forests. Prolonged drought and white pine blister rust (Cronartium rubicola) have decimated limber pine along the Rocky Mountain Front (and elsewhere), resulting in a skeleton woodland with scattered Douglas-firs as the only living trees. At the northern end of its range in Montana, limber pine is mostly associated with common juniper (Juniperus communis) and creeping juniper (Juniperus horizontalis), whereas in the southern end of its range, it is associated with Rocky Mountain juniper. A sparse to moderately dense short-shrub layer is usually present. Within north-central and northwestern Montana, the most common shrubs include bearberry (Arctostaphylos uva-ursi), creeping juniper, shrubby cinquefoil (Dasiphora fruticosa ssp. floribunda),and Canadian buffaloberry (Shepherdia canadensis). Other shrubs that may be present in west-central and southern Montana includebig sagebrush (Artemisia tridentata), black sagebrush (Artemisia nova), curl-leaf mountain mahogany (Cercocarpus ledifolius), rubber rabbitbrush (Ericameria nauseosa), skunkbush sumac (Rhus trilobata), Woods’ rose (Rosa woodsii), common snowberry (Symphoricarpos albus), or western snowberry (Symphoricarpos occidentalis). Herbaceous layers are generally sparse, but range to moderately dense; they are typically dominated by perennial graminoids such as blue grama (Bouteloua gracilis), Idaho fescue (Festuca idahoensis), rough fescue (Festuca campestris), poverty oatgrass (Danthonia intermedia), spike fescue (Leucopoa kingii), needle and thread (Hesperostipa comata), prairie junegrass (Koeleria macrantha), Indian ricegrass (Oryzopsis hymenoides), Sandberg’s bluegrass (Poa secunda), or blue bunch wheatgrass (Pseudoroegneria spicata). Common forbs include yarrow (Achillea millefolium), fringed sage (Artemisia frigida), arrowleaf balsamroot (Balsamorhiza sagittata), prairiesmoke (Geum triflorum), hymenopappus (Hymenopappus species), four-nerve daisy (Hymenoxys species), dotted gayfeather (Liatris punctata), stone seed (Lithospermum ruderale), silver lupine (Lupinus argenteus), pricklypear (Opuntia species), crazyweed (Oxytropis species), and cushion plants such as draba (Draba species), phlox (Phlox species), Rocky Mountain douglasia (Douglasia montana) and Howard’s alpine forget-me-not (Eritrichium howardii).

This system often occurs in complex ecotones on severe sites within other forest systems. It often intergrades with Rocky Mountain Dry-Mesic Montane Mixed Conifer, Rocky Mountain Lower Montane, Foothill and Valley Grassland, Mountain Mahogany Woodland and Shrubland, and Montane Sagebrush Steppe.


National Vegetation Classification Switch to Full NVC View

Adapted from US National Vegetation Classification

A0540 Pinus flexilis Rocky Mountain Woodland Alliance
CEGL000805 Pinus flexilis - Festuca idahoensis Woodland
CEGL000806 Pinus flexilis - Festuca campestris Woodland
CEGL000807 Pinus flexilis - Juniperus communis Woodland
CEGL000810 Pinus flexilis - Leucopoa kingii Woodland
CEGL000815 Pinus flexilis Scree Woodland
A2035 Pinus flexilis Intermountain Basins Forest & Woodland Alliance
CEGL000804 Pinus flexilis - Cercocarpus ledifolius Woodland
A3202 Krascheninnikovia lanata Steppe & Dwarf-shrubland Alliance
CEGL001325 Krascheninnikovia lanata - Phlox spp. Dwarf-shrubland
A3210 Juniperus scopulorum - Juniperus virginiana Woodland Alliance
CEGL000747 Juniperus scopulorum - Piptatherum micranthum Woodland
A3424 Pinus flexilis / Shrub Understory Central Rocky Mountain Woodland Alliance
CEGL000808 Pinus flexilis - Juniperus osteosperma Woodland
CEGL000809 Pinus flexilis - Juniperus scopulorum Woodland
A3425 Pinus flexilis / Grass Understory Central Rocky Mountain Woodland Alliance
CEGL000813 Pinus flexilis - Pseudoroegneria spicata Woodland
A3426 Juniperus osteosperma - Juniperus scopulorum / Shrub Understory Central Rocky Mountain Woodland Alliance
CEGL000734 Juniperus osteosperma - Cercocarpus ledifolius Woodland
CEGL000742 Juniperus scopulorum - Artemisia nova Woodland
CEGL000743 Juniperus scopulorum - Artemisia tridentata Woodland
CEGL000744 Juniperus scopulorum - Cercocarpus ledifolius Woodland
CEGL000745 Juniperus scopulorum - Cercocarpus montanus Woodland
A3427 Juniperus osteosperma - Juniperus scopulorum / Grass Understory Central Rocky Mountain Woodland Alliance
CEGL000748 Juniperus scopulorum - Pseudoroegneria spicata Woodland
A3496 Juniperus osteosperma / Shrub Understory Woodland Alliance
CEGL000730 Juniperus osteosperma - Artemisia tridentata Woodland
A3497 Juniperus osteosperma / Herbaceous Understory Open Woodland Alliance
CEGL000738 Juniperus osteosperma - Pseudoroegneria spicata Open Woodland
*Disclaimer: Alliances and Associations have not yet been finalized in the National Vegetation Classification (NVC) standard.  A complete version of the NVC for Montana can be found here.

Dynamic Processes

Major disturbances in this system include fire, soil erosion from over-used range, and biotic vectors. Clark's nutcrackers have co-adapted an important mutualism with limber pine, and are the primary harvester and disperser of its seeds. These woodlands often originate with and are likely maintained by fire. Regeneration on burns is largely from germination of seedlings from Clark's nutcracker seed caches. Fire can easily kill young limber pine and Rocky Mountain juniper because of their thin bark (Fischer and Clayton, 1983), however, fuel loads in this system are generally light due to open rocky terrain, and fires do not generate severe damage or considerably alter vegetation composition. In comparison with upper treeline limber pine communities, foothill populations are thought to experience greater disturbance frequency (Schuster et al., 1995), and fire return intervals vary between 50 and 400 years (U.S. Department of Agriculture, 2012). Over time limber pine woodlands have shifted both up- and down-slope in response to changing climate and drought, and are considered to be particularly sensitive to future change (Means 2010).

This system occurs on dry, rocky sites that are typified by extreme winter weather and droughty summer conditions that offer marginal conditions for tree growth. Consequently, mortality from abiotic and biotic stressors is high in some areas. Limber pine is highly susceptible to white pine blister rust (Cronartium ribicola), the pine needle pathogen (Dothistroma septospora), and mountain pine beetles (Dendroctonus ponderosae). It can also be heavily infected or killed by limber pine dwarf-mistletoe (Arceuthobium cyanocarpum), particularly in south-central and southwestern Montana (Jackson et al., 2010), and is susceptible to infestation by cone beetles (Conophthorus contortae), the ponderosa pine cone worm (Dioryctria auranticella), and the western conifer seed bug (Leptoglossus occidentalis). Resistance to blister rust and mountain pine beetle is lower for limber pine than for other North American pines affected by these biotic agents (Hoff and McDonald 1993; Means 2010), and drought can exacerbate vulnerability to pine beetle attack (Jackson et al., 2010). The most significant damage due to biotic factors appears to occur at locations on the Lewis and Clark National Forest along the northern Rocky Mountain Front, the Gravelly range and sections of the Yellowstone ecosystem in southwestern Montana. Large numbers of trees have very thin crowns and poor terminal growth, and severe mortality is occurring in some areas.

Under natural conditions, Rocky Mountain juniper seedlings become established on moist sites in partial shade (Burns and Honkala 1990). Stands found in southwestern Montana may exhibit a savanna-like character due to the inability of Rocky Mountain juniper to establish on drier micro-sites. Rocky Mountain juniper is generally shallow rooted, and forest health can be negatively affected by heavy grazing, especially on exposed sites with erodible soils. Although Rocky Mountain juniper is relatively resistant to disease and tolerant of insects, several insect pests do attack this species including cedar flathead borers () and bark beetles (Phloeosinus spp.) (Scher, 2002). Additionally, mistletoes (Phoradendron spp.), a blight caused by Cercospora sequoia, and cedar apple rust (Gymnosporangium juniper virgiananae) can be especially problematic (Burns and Honkala 1990).


Management
In the absence of natural fire, periodic low to moderate intensity prescribed burns can be implemented during late fall months to maintain and enhance limber pine regeneration, although results may be variable due to insufficient ground fuels and rocky terrain typical of this system. Fire may kill young trees of limber pine and Rocky Mountain juniper because of their thin bark. Thinning may also be used in particularly dense stands to reduce spread of mountain pine beetles (Bureau of Land Management, 2011). In light of blister rust prevalence, stands can be managed to maintain limber pine forest composition, and to diversify age structure to include regeneration, thereby encouraging natural selection of rust resistant individuals (Jackson et al., 2010). On sites with slopes and forage that support domestic livestock, use can be monitored to maintain soil integrity.

Restoration Considerations

Reintroduction of prescribed fire fosters limber pine restoration because it provides open sites and exposed mineral soils that are suitable for Clark's nutcracker to cache seeds, and for seedlings to establish. Augmenting natural limber pine regeneration with seed sources that exhibit some resistance to blister rust or, in some cases, with nursery stock, will be necessary in areas where seed sources are absent or greatly reduced. Blister rust-resistant or tolerant trees can be identified in previously infected stands, or by screening for an identified resistance gene (Schoettle and Sniezko 2007; Schoettle et al. 2014). Direct seeding may be the most practical restoration method on most sites, however seed-transfer guidelines should be considered when the seed source is a considerable distance from the seeding site (Schoettle and Sniezko 2007). Germination will take place during the first growing season after fall caching or direct seeding.

Because this system is characterized by shallow soils, outplanting of nursery stock may be limited to microsites with deeper soil pockets. Out-planted seedling survival has been shown to be higher when seedlings are planted on microsites with some cover, when seedlings are planted in clumps rather than singly, and when competition from surrounding vegetation is minimized (Asebrook et al. 2011). Seedling health was marginally improved in burned areas compared to unburned areas within an experimental area in Waterton Lakes National Park, Alberta (Asebrook et al., 2006).


Species Associated with this Ecological System
  • Details on Creation and Suggested Uses and Limitations
    How Associations Were Made
    We associated the use and habitat quality (common or occasional) of each of the 82 ecological systems mapped in Montana for vertebrate animal species that regularly breed, overwinter, or migrate through the state by:
    1. 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, Foresman 2012, Adams 2003, and Werner et al. 2004);
    2. Evaluating structural characteristics and distribution of each ecological system relative to the species' range and habitat requirements;
    3. Examining the observation records for each species in the state-wide point observation database associated with each ecological system;
    4. Calculating the percentage of observations associated with each ecological system relative to the percent of Montana covered by each ecological system 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, and species that only migrate through Montana were only evaluated for migratory habitat use.  In general, species were listed as associated with an ecological system if structural characteristics of used habitat documented in the literature were present in the ecological system or large numbers of point observations were associated with the ecological system.  However, species were not listed as associated with an ecological system if there was no support in the literature for use of structural characteristics in an ecological system, even if point observations were associated with that system.  Common versus occasional association with an ecological system was assigned based on the degree to which the structural characteristics of an ecological system matched the preferred structural habitat characteristics for each species as represented in scientific literature.  The percentage of observations associated with each ecological system relative to the percent of Montana covered by each ecological system was also used to guide assignment of common versus occasional association.  If you have any questions or comments on species associations with ecological systems, please contact the Montana Natural Heritage Program's Senior Zoologist.

    Suggested Uses and Limitations
    Species associations with ecological systems 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 (this information can be requested at: http://mtnhp.org/requests/default.asp) or systematic surveys for species and evaluations of habitat at a local site level by trained biologists.  Users of this information should be aware that the land cover data used to generate species associations is based on imagery from the late 1990s and early 2000s and was only intended to be used at broader landscape scales.  Land cover mapping accuracy is particularly problematic when the systems 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 ecological system within its known geographic range, portions of that ecological system 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.
    • 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.
    • 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.

Original Concept Authors
G. Jones, K. Schulz, mod. G. Kittel (NatureServe ed. date 20Apr2006)

Montana Version Authors
T. Luna, L.K. Vance, M. Hart

Version Date
1/1/2017

References
  • Classification and Map Identifiers

    Cowardin Wetland Classification: Not applicable

    NatureServe Identifiers:
    Element Global ID
    System Code CES306.955, Rocky Mountain Foothill Limber Pine - Juniper Woodland

    National Land Cover Dataset:
    42: Evergreen Forest

    ReGAP:
    4236: Rocky Mountain Foothill Limber Pine - Juniper Woodland


  • Literature Cited AboveLegend:   View Online Publication
    • Asebrook, J.M., J. Lapp, and T. Carolin. 2011. Whitebark and limber pine restoration and monitoring in Glacier National Park. Pp. 335-337 In: Proceedings of the high five symposium on the future of high-elevation, five-needle white pines in western North America, Keane, R.E., Tomback, D.F., Murray, M.P., and Smith, C.M. Missoula, MT: USDA Forest Service, Rocky Mountain Research Station. RMRS-P-63.
    • Bureau of Land Management (BLM). 2011 Whitebark and Limber Pine (Five Needle Pine) Management Guidelines for Wyoming BLM. In: FY 2011 Memorandums. Wyoming: U.S. Department of the Interior, Bureau of Land Management.
    • Fischer, W.C. and B.D. Clayton. 1983. Fire ecology of Montana. Forest habitat types east of the continental divide. USDA, Forest Service Gen. Tech. Rpt. INT-141.
    • Hoff, R.J. and G.I. McDonald. 1993. Variation of virulence of white pine blister rust. European journal of forest pathology 23(2):103-109.
    • Jackson, M., A. Gannon, H. Kearns, K. Kendall. 2010. Current Status of Limber Pine in Montana. Report 10-06. Missoula, MT: U.S. Department of Agriculture, Forest Service, Northern Region. 14 p.
    • Means, R.E. 2010. Synthesis of lower treeline limber pine (Pinus flexilis) woodland knowledge, research needs, and management considerations. Pp. 29-36 In: Proceedings of the high five symposium on the future of high-elevation, five-needle white pines in western North America, Keane, R.E., Tomback, D.F., Murray, M.P., and Smith, C.M. Missoula, MT: USDA Forest Service, Rocky Mountain Research Station. RMRS-P-63.
    • 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.
    • Scher, J.S. 2002. Juniperus scopulorum. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory.
    • Schoettle, A.W. and R.A. Sniezko. 2007. Proactive intervention to sustain high-elevation pine ecosystems threatened by white pine blister rust. Journal of Forest Research 12(5):327-336.
    • Schoettle, A.W., R.A. Sniezko, R.A., A. Kegley, and K.S. Burns. 2014. White pine blister rust resistance in limber pine: evidence for a major gene. Phytopathology 104(2):163-173.
    • Schuster, W.S., J.B. Mitton, D.K. Yamaguchi, and C.A. Woodhouse. 1995. A comparison of limber pine (Pinus flexilis) ages at lower and upper treeline sites east of the Continental Divide in Colorado. American Midland Naturalist 133(1):101-111.
    • U.S. Department of Agriculture, Forest Service, Missoula Fire Sciences Laboratory. 2012. Information from LANDFIRE on Fire Regimes of Limber Pine Communities. In: Fire Effects Information System. Missoula, MT: USDA Forest Service, Rocky Mountain Research
  • Additional ReferencesLegend:   View Online Publication
    Do you know of a citation we're missing?
    • Asebrook, J.M. 2006. Revegetation Monitoring Reports: Glacier National Park. West Glacier, MT: Research Reports, Glacier National Park.
    • 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.
    • Cooper, S.V., C. Jean, and B.L. Heidel. 1999. Plant associations and related botanical inventory of the Beaverhead Mountains Section, Montana. Unpublished report to the Bureau of Land Management. Montana Natural Heritage Program, Helena. 235 pp.

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Rocky Mountain Foothill Limber Pine - Juniper Woodland.  Montana Field Guide.  Retrieved on , from