Search Field Guide
Advanced Search
MT Gov Logo
Montana Field Guide

Montana Field Guides

Lowland - Montane Riparian Deciduous Forest
Global Name: Central Rocky Mountain Lowland & Foothill Riparian Forest

No photos are currently available

Global Rank: G3?
State Rank: S3S4

(see reason below)

External Links




State Rank Reason
These riparian habitats have experienced some decrease in condition and extent due to hydrologic changes and water use, and from invasion by non-native species. However, they are still relatively abundant along major drainages in the western portion of the state.
 

General Description
This National Vegetation Classification Group is a riparian, forested group dominated primarily by Black Cottonwood. In Montana, this group occurs on both sides of the Continental Divide from valley bottoms into the foothills and montane zones along rivers and streams, lake margins and other wet sites. It is more common west of the Divide; east of the Divide it is more localized and scattered along low elevation streams and rivers into the montane zone in the island ranges of central Montana. It encompasses riparian forest and woodland communities dominated by Black Cottonwood (Populus balsamifera ssp. trichocarpa) or Balsam Poplar (Populus balsamifera ssp. balsamifera). These two taxa are practically indistinguishable and are often treated as a single species. In many stands, Quaking Aspen (Populus tremuloides) may be present or co-dominate. Conifer species such as Ponderosa Pine (Pinus ponderosa), Douglas-fir (Pseudotsuga menziesii) or Engelmann Spruce may be present. The undergrowth may be dominated by various shrubs or herbaceous species. Black Cottonwood communities often occur in a mosaic with willow-dominated riparian habitats.

This group is similar to the Northern Rocky Mountain Lower Montane Riparian Woodland and Shrubland and the Rocky Mountain Lower Montane-Foothill Riparian Woodland and Shrubland Ecological Systems.

Diagnostic Characteristics
Riparian & Wetland Forest; Rocky Mountain Region; Valleys, Foothills and Montane Zones; Floodplains; Deciduous Trees

Typical Dominants: Black Cottonwood (Populus balsamifera ssp. trichocarpa), Balsam Poplar (Populus balsamifera ssp. balsamifera)

Similar Systems

Range
In Montana, this group is found primarily west of the Continental Divide from the major river drainages to montane streams. East of the Divide, it is more localized and scattered along low elevation streams and rivers into the montane zone of the island ranges of central Montana.

In MT, G796 occurs within these Level III Ecoregions: 15 (Northern Rockies), 16 (Idaho Batholith), 17 (Middle Rockies), and 41 (Canadian Rockies).

In Montana, G796 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, Lincoln, Madison, Meagher, Missoula, Musselshell, Park, Phillips, Powell, Ravalli, Sanders, Stillwater, Sweet Grass, Teton, Valley, Wheatland
Based on 2025 land cover layer.

Spatial Pattern
Small Patch

Environment
These riparian communities occur at lower elevations in valleys and in the foothills and montane zones on alluvial terraces, streambanks, and floodplains along low to gradient streams and rivers. Soils are usually Entisols overlying river cobbles and gravel. Inceptisols and Mollisols can be found on older sites of relative stability that have had significant time for soil development. Soil texture varies from loam to coarse sand. Water tables may drop in late summer to 50 centimeters (20 inches) below the soil surface, but surface horizons remain moist due to capillary action. The coarse textured soils, stream gradients, and large amounts of coarse rock fragments create rapid movement of highly aerated water. Sites occur at elevations of 2,500-4,000 feet west of the Continental Divide. East of the Continental Divide, this group ranges up to 5,500 feet (Hansen et al. 1995). This group is dependent on a natural hydrologic regime, especially annual or episodic flooding. Occurrences are found within the flood zone of major rivers and the associated islands, sand or cobble bars, and along adjacent streambanks. It can occur as a large, wide patch on mid-channel islands in larger rivers or as narrow bands along small, montane streams and on well-drained benches. It is also found along backwater channels and other perennially wet but less scoured sites, such as floodplains, swales and irrigation ditches.

Vegetation
This group encompasses riparian forest and woodland communities dominated by Black Cottonwood (Populus trichocarpa or Populus balsamifera ssp. trichocarpa) or Balsam Poplar (Populus balsamifera ssp. balsamifera). These two taxa are practically indistinguishable and are often treated as a single species. In many stands, Quaking Aspen (Populus tremuloides) may be present or co-dominate. Conifer species such as Ponderosa Pine (Pinus ponderosa), Douglas-fir (Pseudotsuga menziesii) or Engelmann Spruce may be present, especially in older stands or on more stable floodplains. The undergrowth may be dominated by various shrubs or herbaceous species. Common shrubs include Woods’ Rose (Rosa woodsii), Western Snowberry (Symphoricarpos occidentalis), Common Snowberry (Symphoricarpos albus), Red-osier Dogwood (Cornus sericea), Currants and Gooseberries (Ribes spp), Serviceberry (Amelanchier alnifolia), Chokecherry (Prunus virginiana) and willows (Salix spp). Common graminoids are mainly non-native species and include Kentucky Bluegrass (Poa pratensis) Canada Bluegrass (Poa compressa), Common Timothy (Phleum pratense, Redtop (Agrostis stolonifera) (Hansen etal 1995). The forb component ranges from very sparse to moderately dense or patchy with a diversity of potential native and non-native species within these habitats. Individual associations should be referenced for common forbs in each type.

This group includes 1 Alliance with 10 Associations within the National Vegetation Classification, which are attributed to MT. Several of the Associations are very similar and may represent ecotones. Some Associations such as the Populus balsamifera ssp. trichocarpa - Populus tremuloides - Conifer/Calamagrostis canadensis Riparian Forest (CEGL005909) are also very similar to the Populus tremuloides/Calamagrostis canadensis Swamp Forest Association (CEGL000574), which is part of G505 Rocky Mountain-Great Basin Swamp Forest. Also contained in this group at the current time is an Abies lasiocarpa - Thuja plicata/ Oplopanax Wet Slope Forest Alliance (A2216) which has no related Associations and no description of the concept. This Alliance is very similar to vegetation types currently within the concept of G505 Rocky Mountain-Great Basin Swamp Forest including the Abies lasiocarpa - Picea engelmannii/Oplopanax horridus Swamp Forest Association (CEGL000322) and the Thuja plicata - Tsuga heterophylla/Oplopanax horridus Rocky Mountain Swamp Forest Association (CEGL000479). A2216 if a valid and distinct concept should almost certainly be combined with similar types in G505.

National Vegetation Classification

Download the complete NVC hierarchy for Montana

TP1 B08 Palustrine Wetland
TP1.a S69 Forested Wetland
TP1.a2 F136 Temperate-Boreal Forested Wetland
TP1.a2.Nd D195 Rocky Mountain-Great Basin Montane Flooded and Swamp Forest
TP1.a2.Nd.1 M034 Rocky Mountain-Great Basin Montane Riparian and Swamp Forest
TP1.a2.Nd.1.c G796 Central Rocky Mountain Lowland and Foothill Riparian Forest
A0311 Populus balsamifera ssp. trichocarpa Central Rockies Riparian Forest Alliance
CEGL000542 Populus balsamifera ssp. trichocarpa - (Populus tremuloides) / Heracleum maximum Riparian Forest
CEGL000670 Populus balsamifera ssp. trichocarpa / Betula papyrifera Riparian Forest
CEGL000672 Populus balsamifera ssp. trichocarpa / Cornus sericea Riparian Forest
CEGL000675 Populus balsamifera ssp. trichocarpa / Phleum pratense - Mixed Herbs Ruderal Riparian Forest
CEGL000677 Populus balsamifera (ssp. trichocarpa, ssp. balsamifera) / Symphoricarpos (albus, oreophilus, occidentalis) Riparian Forest
CEGL005845 Populus balsamifera ssp. trichocarpa / Calamagrostis canadensis Riparian Forest
CEGL005905 Populus balsamifera ssp. trichocarpa - Populus tremuloides - Conifer / Cornus sericea Riparian Forest
CEGL005906 Populus balsamifera ssp. trichocarpa - Populus tremuloides - Conifer / Clintonia uniflora Riparian Forest
CEGL005907 Populus balsamifera ssp. trichocarpa - Picea engelmannii / Equisetum arvense Riparian Forest
CEGL005909 Populus balsamifera ssp. trichocarpa - Populus tremuloides - Conifer / Calamagrostis canadensis Riparian Forest
CEGL005910 Populus balsamifera ssp. trichocarpa - Populus tremuloides - Conifer / Heracleum maximum Riparian Forest
A2216 Abies lasiocarpa - Thuja plicata / Oplopanax Wet Slope Forest Alliance
View more information on the NVC standard in Montana
*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
Flooding is crucial for the establishment and maintenance of Cottonwood stands within floodplain environments and acts as primary control on plant succession. High flow events lead to scouring and deposition of gravels and sediments where Cottonwoods can establish. Sediment accumulating in these systems often creates gravel bars at or near the surface of the river, creating bands of mixed vegetation occupying different stages of succession. Increasing vegetation traps even more sediment, so that over time the size and height of the gravel bar increases. Cottonwoods and the associated shrub understory are adapted to these flooding events.

Management
Alteration of hydrology by dams and diversions are major influences on the structure, composition, and function of cottonwood communities. In Montana, dams have eliminated the ability of cottonwood to regenerate by seeds in many places. As the cottonwood stand dies, successional processes will tend toward other communities unless flooding deposits new sediments that support seedling regeneration. Heavy grazing by cattle, or in some cases by elk and deer, along these streams and rivers can result in increased erosion and eliminate the vegetative regeneration of cottonwood sprouts. In sites where there is prolonged disturbance, shrub cover will decrease, resulting in a more open canopy.

Restoration Considerations
Maintaining an undisturbed buffer strip of cottonwood species adjacent to rivers and streams can stabilize riverbanks and will serve as a source for seedling and branch colonization if the hydrology of the river system is restored. Cottonwood requires full sunlight and a moist seed bed for colonization. If the site still has a fairly high water table and a remnant shrub population, the shrubs are capable of resprouting and will stabilize embankments and reduce sedimentation. If the site is highly impacted, seedlings or live cuttings can be used for more intensive restoration practices.

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:
    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, Werner et al. 2004, Adams 2003, and Foresman 2012);
    2. Evaluating structural characteristics and distribution of each vegetation community 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 vegetation community;
    4. 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.

Original Concept Authors
G. Kittel (2015)

Montana Version Authors
S. Mincemoyer, L. Vance, C. McIntyre, T. Luna

Version Date
12/6/2024


References
  • Literature Cited AboveLegend:   View Online Publication
    • 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.
Login Logout
Citation for data on this website:
Lowland - Montane Riparian Deciduous Forest.  Montana Field Guide.  Retrieved on , from