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Rocky Mountain Subalpine-Montane Riparian Woodland

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General Description

This riparian woodland system includes seasonally flooded forests and woodlands found at montane to subalpine elevations in the Rocky Mountains. This habitat ranges from narrow streamside forests lining, confined low-order mountain streams to stands along broader, meandering tributaries, but they are typically dominated by coniferous tree species. Stands generally occur at elevations between 4,600 and 8,800 feet. In subalpine environments where there are steep gradients and high-energy flows controlled by precipitation and hydrological events, the transport and accumulation of sediments constantly creates and destroys sites for the establishment of vegetation (Melanson and Butler, 1991). In western Montana, this system is typically dominated by grand fir (Abies grandis), subalpine fir (Abies lasiocarpa), Engelmann spruce (Picea engelmannii), western red cedar (Thuja plicata) and western hemlock (Tsuga heterophylla) in moister sites, and by Douglas-fir (Pseudotsuga menziesi), ponderosa pine (Pinus ponderosa), and Rocky Mountain juniper (Juniperus scopulorum) in drier areas (Ellis and Richard, 2003). The understory in this riparian system is typically sparse, but along the banks and on gravel bars, willow (Salix spp.), alder (Alnus spp.) and redosier dogwood (Cornus sericea) can be found. These riparian conifer types contribute to animal and plant diversity because they tend to have a more diverse forest structure than adjacent upland habitats. Although riparian areas make up a relatively small percent of cover in the Rocky Mountain West, they provide important migratory corridors, foraging areas and shade cover for Montana’s birds, fish, insects and mammals (Ellis and Richard, 2003).


Diagnostic Characteristics
montane, forest and woodland, riverine, alluvial, short flooding interval (< 5 years)

Similar Systems

Range
This system is found at montane to subalpine elevations in the Rocky Mountains, from southern New Mexico north into Montana, Alberta and British Columbia, and west into the Intermountain region and the Colorado Plateau. In Montana, riparian conifer systems are found throughout the state, but are more common in the moister forested regions west of the Continental Divide.

Ecological System Distribution
Approximately 21 square kilometers are classified as Rocky Mountain Subalpine-Montane Riparian Woodland in the 2013 Montana Land Cover layers.  Grid on map is based on USGS 7.5 minute quadrangle map boundaries.



Montana Counties of Occurrence
BROADWATER, CARBON, FLATHEAD, GALLATIN, LINCOLN, MEAGHER, MISSOULA, PARK, POWELL, RAVALLI, STILLWATER, SWEET GRASS, WHEATLAND

Spatial Pattern
Linear

Environment

This riparian woodland system includes seasonally flooded forests and woodlands found at montane to subalpine elevations of the Rocky Mountains. Stands typically occur at elevations between 4,600-8,800 feet. This system is common to the poorly-developed floodplains and terraces of V-shaped, narrow valleys and canyons, and less frequently, it occurs in moderate to wide valley bottoms on large floodplains along broad, meandering rivers such as the South Fork of the Flathead, and on pond or lake margins. In subalpine environments where there are steep gradients and high-energy flows controlled by precipitation and hydrological events, the transport and accumulation of sediments constantly creates and destroys sites for the establishment of vegetation (Melanson and Butler, 1991).


Vegetation

Vegetation composition and structure can vary depending on latitude, elevation and climate. A woody riparian area in the subalpine zone of the Rocky Mountains in Montana is typically dominated by grand fir, subalpine fir and Engelmann spruce. Grand fir and Engelmann spruce are considered late seral species, while subalpine fir is predominantly found in climax communities at higher elevations or at lower elevations in frost pockets (Hansen et al., 1995). In the montane zone, dominant vegetation changes to a community dominated by ponderosa pine, western larch (Larix occidentalis) and Douglas fir (Pseudotsuga menziesii). Western red cedar (Thuja plicata) and western hemlock (Tsuga heterophylla) occur in moister sites west of the Continental Divide, and Some sites support Rocky Mountain juniper. The understory is typically sparse, but along the banks and on gravel bars, willow, alder and redosier dogwood can be present. Some sites support scattered black cottonwood (Populus balsamnifera) and/or small stands of quaking aspen (Populus tremuloides). The vegetation in these systems relies on a consistent shallow water table to meet individual plant requirements; however, periodic flooding is necessary for community maintenance. Flooding transports sediments and creates establishment sites for plant colonization. Many plants have acquired adaptive traits as a result of this disturbance regime. Mechanical adaptations such as stem flexibility and specialized oxygen-holding cells assist riparian plants to endure through the physical strains of flooding. Reproductive adaptations, including water-dispersible seeds, vegetative budding, and adventitious roots allow plants to colonize and regenerate by seed and asexual methods.

The understory shrub species often form in a narrow band in the gravel bars and embankments along the stream channel. In the montane zone, species such as thinleaf alder (Alnus incana), redoiser dogwood and willows such as Bebb’s willow (Salix bebbiana), Booth’s willow (Salix boothii), Drummond’s willow (Salix drummondiana), dusky willow (Salix melanopsis), and Geyer’s willow (Salix geyeriana) are common. In western Montana riparian forests dominated by spruce or subalpine fir, devil’s club (Oplopanax horridus) may be a codominate in the understory, but this is an infrequent plant association. Other minor shrubs include thimbleberry (Rubus parviflorus), elderberry (Sambucus species), Douglas hawthorn (Crataegus douglasii), black twinberry (Lonicera involucrata), alder buckthorn (Rhamnus alnifolia), serviceberry (Amelanchier alnifolia), common snowberry (Symphoricarpos albus) and Woods’ rose (Rosa woodsii).

In the subalpine elevations, sitka alder (Alnus viridis) and Drummond’s willow are frequently dominant. Water birch (Betula occidentalis) or resin birch (Betula glandulosa) may also be present. Planeleaf willow (Salix planifolia), undergreen willow (Salix commutata), Barclay’s willow (Salix barclayi), shortfruit willow (Salix brachycarpa) and grayleaf willow (Salix glauca) become common at higher elevations. Herbaceous vegetation forms a minor component of this system but may include small patches of bluejoint reedgrass (Calamagrostis canadensis), drooping woodreed (Cinna latifolia) and sedges such water sedge (Carex aquatilis). Common forbs include arrowleaf groundsel (Senecio triangularis), angelica (Angelica spp.) baneberry (Actaea rubra) western meadow rue (Thalictrum occidentale), starry solomon’s seal (Maianthemum stellatum), fragrant bedstraw (Galium triflorum), Virginia strawberry (Fragaria virginiana), sweet-cicely (Osmorhiza species), common cow parsnip (Heracleum maximum), clasp-leaf twistedstalk (Streptopus amplexifolius) and green false hellebore (Veratrum viride). Common ferns and fern allies are often present, such as horsetail (Equisetum species), American ladyfern (Athryium filix-femina), and oak fern (Gymnocarpium dryopteris).


Alliances and Associations
Alliances
  • (A.311) Black Cottonwood Temporarily Flooded Forest Alliance
  • (A.191) Engelmann Spruce Seasonally Flooded Forest Alliance
  • (A.572) Engelmann Spruce Seasonally Flooded Woodland Alliance
  • (A.179) Engelmann Spruce Temporarily Flooded Forest Alliance
  • (A.566) Engelmann Spruce Temporarily Flooded Woodland Alliance
  • (A.188) Lodgepole Pine Seasonally Flooded Forest Alliance
  • (A.175) Lodgepole Pine Temporarily Flooded Forest Alliance
  • (A.562) Lodgepole Pine Temporarily Flooded Woodland Alliance
  • (A.274) Quaking Aspen Forest Alliance
  • (A.340) Quaking Aspen Seasonally Flooded Forest Alliance
  • (A.300) Quaking Aspen Temporarily Flooded Forest Alliance
  • (A.422) Subalpine Fir - Quaking Aspen Forest Alliance
  • (A.190) Subalpine Fir Seasonally Flooded Forest Alliance
  • (A.177) Subalpine Fir Temporarily Flooded Forest Alliance

Dynamic Processes
Stochastic flood events and variable fluvial conditions are crucial to the development of establishment sites for riparian plants, and actl as a primary control on plant succession. Steep gradients and high-energy flows controlled by precipitation causes flooding events that transport sediments. The scouring out and accumulation of sediments creates and destroys sites for the establishment of vegetation (Melanson and Butler, 1991). Sediment accumulating in more meandering examples of these systems often creates gravel bars at or near the surface of the water where colonizing vegetation creates bands of mixed vegetation that occupies different stages of succession (Melanson and Butler, 1991). Ground water seepage from snowmelt may create shallow water tables or seeps that vegetation depends on for a portion of the growing season

Management

Grazing along narrow, low order streams can result in increased erosion and channel downcutting (Mitsch and Gosellink, 2000). Sites that are subjected to heavy grazing practices may transition to an herbaceous understory consisting of introduced grasses and forbs such as Kentucky bluegrass (Poa pratensis) and Canadian thistle (Cirsium arvense). In addition, fire suppression, timber harvest and reduced flood frequency can affect the succession of riparian communities.


Restoration Considerations

Restoration strategies are dependent on the degree and type of disturbance event. Restoration efforts must first concentrate on restoring thestream's hydrology, so floods can re-occur. In-stream habitat enhancement (e.g., additions of logs or boulders) should be employed after restoring natural processes or where short-term improvements in habitat are needed (e.g., for species in recovery).

Removing or strictly limiting grazing by livestock and wildlife will allow the system to recover if hydric soils have not been lost due to extensive soil compaction, pugging, or down cutting of stream channels, and if there are existing populations of herbaceous native species (Carex, Juncus, and native grasses) that possess rhizomatous root systems capable of re-colonizing bare soils. Rhizomatous, highly adaptable exotic grasses such as Kentucky bluegrass, common timothy and smooth brome and pasture forbs such as clovers (Trifoliumspecies) and common dandelion (Taraxacum officinale) will persist on the site and may compete with existing populations of native graminiods and forbs. In these cases, land managers must determine whether the exotic density is small enough that an adequate stand of native graminoids and forbs can become established on the site if reseeding efforts are used. In all cases, grazing must be excluded for several years to allow adequate re-growth and recovery of existing shrubs and the herbaceous understory.

Because all major shrub species within this riparian system are capable of re-sprouting and typically possess extensive, spreading root systems, modified land management practices in areas of low to moderate impact can minimize additional restoration needs. Vigor, health and degree of vegetative regeneration of existing trees and shrubs must be evaluated to determine if these components of the community are capable of recovery in an acceptable time frame. Intensive revegetation efforts should be limited to sites where a catastrophic wildfire or prolonged heavy grazing has destroyed existing trees, shrubs and the seed bank.


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 (high, medium, or low) 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 2001, 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 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 associated as using 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 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.  High, medium, and low habitat quality was assigned based on the degree to which the structural characteristics of an ecological system matched the preferred structural habitat characteristics for each species in the 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 assignments of habitat quality.  If you have any questions or comments on species associations with ecological systems, please contact Bryce Maxell at bmaxell@mt.gov or (406) 444-3655.

    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.  2001.  The wild mammals of Montana.  Special Publication No. 12.  Lawrence, KS: The American Society of Mammalogists.  278 p.
    • 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
Natureserve Western Ecology Group

Montana Version Authors
L.K. Vance, C. McIntyre, T. Luna

Version Date
2/15/2010

References
  • Classification and Map Identifiers

    Cowardian Wetland Classification:
    System Palustrine
    Class Forested Wetland
    Water Regime Temporarily to seasonally flooded
    Geographically Isolated Wetland No


    National Vegetation Classification Standard:
    Class Forest and Woodland
    Subclass Temperate Forest and Woodland
    Formation Temperate Flooded and Swamp Forest
    Division Western North America Flooded and Swamp Forest
    Macrogroup Rocky Mountain and Great Basin Flooded and Swamp Forest

    NatureServe Identifiers:
    Element Global ID 28668
    System Code CES306.833, Rocky Mountain Subalpine-Montane Riparian Woodland

    ReGAP:
    9171: Rocky Mountain Subalpine-Montane Riparian Woodland


  • Additional ReferencesLegend:   View WorldCat Record   View Online Publication
    Do you know of a citation we're missing?
    • Cowardin, L.M., et al. 1979. Classification of wetlands and deepwater habitats of the United States. U.S. Fish and Wildlife Service, FWS/OBS-79/31. 103pp.
    • Ellis, Janet H., and Jim Richards. 2003. A planning guide for protecting Montana's wetlands and riparian areas. Bozeman, MT: Montana Watercourse.

    • Hansen, P. L., R. D. Pfister, K. Boggs, B. J. Cook, J. Joy, and D. K. Hinckley. 1995. Classification and management of Montana's riparian and wetland sites. Montana Forest and Conservation Experiment Station, School of Forestry, University of Montana, Miscellaneous Publication No. 54. 646 pp. + posters.
    • Malanson, George P., and David R. Butler. 1991. "Floristic Variation among Gravel Bars in a Subalpine River, Montana, U.S.A.". Arctic and Alpine Research. 23 (3): 273-278.
    • Mitsch WJ, Gosselink JG. 2000. Riparian Ecosystems. In: Wetlands. 3rd Edition. John Wiley and Sons, Inc. 920 p.

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Citation for data on this website:
Rocky Mountain Subalpine-Montane Riparian Woodland.  Montana Field Guide.  Retrieved on September 1, 2014, from http://FieldGuide.mt.gov/displayES_Detail.aspx?ES=9171
 
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