Great Plains Wet Meadow, Marsh and Shrub Swamp
Global Rank:
GNR
State Rank:
S3S4
(see reason below)
External Links
State Rank Reason
These freshwater wetlands are widespread though they occupy a small area. They have experienced past declines and continue to experience threats from invasive species, grazing practices, agriculture, hydrologic changes, water use and development. The uncertainty in or lack of data available for this group in terms of condition and degree of threats leads to uncertainty in the overall rank.
General Description
This National Vegetation Classification Group is composed of herbaceous-dominated wet meadows (wet prairie) and freshwater marshes as well as localized areas of riparian or wetland shrub communities throughout areas of the Great Plains region. This is a minor group in Montana with a sporadic distribution and relatively poor documentation. The wet meadows (wet prairie) component of this group occurs along drainages, in basins and lowland sites in areas flooded for brief periods during the growing season via runoff or that flood after snowmelt or heavy rains. These lowland sites often have standing water for several weeks each year and they are commonly dominated by Sedges (Carex spp), Western Wheatgrass (Elymus smithii), Prairie Cordgrass (Spartina pectinata), or Switchgrass (Panicum virgatum).
Prairie marshes occur mostly as small patches on the landscapes and are largely confined to limited areas in suitable floodplain or basin topography. They are seasonally, semi-permanently or permanently flooded habitats. Water is at or above the soil surface for most of the growing season. This group includes shallow, freshwater to slightly brackish waters found in bottomlands along drainages, in river floodplain depressions, along side channels, and at the margins of, ponds, stock ponds, ditches and slow-moving streams. A consistent source of freshwater is essential to the function of these communities. Vegetation communities include those dominated by Cattails (Typha sp), Bulrushes (Schoenoplectus spp, Scirpus spp), Sedges (Carex spp), Rushes (Juncus spp), Spikerushes (Eleocharis spp). Soils are muck, mineral, or muck over mineral soil, and water is high in nutrients. This wetland group occurs throughout the Great Plains region and is separable from the related G531 Arid West Freshwater Marsh & Wet Meadow primarily by geography.
Wet or riparian shrublands usually dominated by Sandbar Willow (Salix exigua, Salix interior) are found along rivers and streams, typically in alluvial sand or gravel. Heights of these shrubland communities are less than 15ft tall. They also occur along irrigation ditches, and other low wet areas that are not subject to frequent flooding and scouring.
This group encompasses portions of the Emergent Marsh, the Great Plains Closed Depressional Wetland, the Great Plains Open Freshwater Depressional Wetland and the Great Plains Prairie Pothole Ecological Systems.
Diagnostic Characteristics
Wetlands; Marsh and Wet Meadow; Shrubby wetlands; Herbaceous or Shrub Dominated; Great Plains Region; Seasonally, Vernally or Permanently Saturated; Hydric Soils
Typical Dominants: Sedges (Carex spp), Western Wheatgrass (Elymus smithii), Prairie Cordgrass (Spartina pectinata), Switchgrass (Panicum virgatum), Spikerushes (Eleocharis), Cattails (Typha sp), Bulrushes (Schoenoplectus spp, Scirpus spp); Rushes (Juncus spp); Sandbar Willow (Salix exigua, Salix interior)
Similar Systems
Range
This wetland group occurs sporadically throughout the Great Plains Region in Montana, excluding areas in or adjacent to the island mountain ranges that are more appropriately classified as G521, G526, or G531.
In Montana, G1213 occurs in Level III Ecoregions: 42 (Northwestern Glaciated Plains) and 43 (Northwestern Great Plains).
In Montana, G1213 occurs or potentially occurs within these Major Land Resource Areas: 52 - Brown Glaciated Plains, 53A - Northern Dark Brown Glaciated Plains, 53B - Central Dark Brown Glaciated Plains, 54 - Rolling Soft Shale Plain, 58A,B,C,D - Northern Rolling High Plains, 60A,B - Pierre Shale Plains.
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
Big Horn, Blaine, Broadwater, Carbon, Carter, Cascade, Chouteau, Custer, Daniels, Dawson, Fallon, Fergus, Gallatin, Garfield, Glacier, Golden Valley, Hill, Judith Basin, Lewis and Clark, Liberty, Mccone, Meagher, Musselshell, Park, Petroleum, Phillips, Pondera, Powder River, Prairie, Richland, Roosevelt, Rosebud, Sheridan, Stillwater, Sweet Grass, Teton, Toole, Treasure, Valley, Wheatland, Wibaux, Yellowstone
Based on 2025 land cover layer.
Spatial Pattern
Small Patch
Environment
The wet meadows (wet prairie) component of this group occurs along drainages, in basins and lowland sites in areas flooded for brief periods during the growing season via runoff or that flood after snowmelt or heavy rains. These lowland sites often have standing water for several weeks each year. The water may be fresh or mildly saline. Soils can be mineral but mucks often form through the buildup of organic material (Looman 1982).
Marshes occur mostly as small patches on the landscape and are largely confined to limited areas in suitable floodplain or basin topography. They are seasonally, semi-permanently or permanently flooded habitats. Water is at or above the soil surface for most of the growing season and includes shallow freshwater to slightly brackish waters found in bottomlands along drainages, in river floodplain depressions, along side channels, below seeps and at the margins of lakes, ponds, stock ponds, ditches and slow-moving streams. Sites can have water levels from completely drained (exposed soil) to approximately 1.5 meters deep but are usually is less than 1 meter. Water levels can vary by up to 1 m during the year. A consistent source of freshwater is essential to the function of these communities. Soils are muck, mineral, or muck over mineral soil, and water is high in nutrients.
Wet or riparian shrublands usually dominated by Sandbar Willow (Salix exigua, Salix interior) are found along rivers and streams, typically in alluvial sand or gravel. They also occur along irrigation ditches, and other low wet areas that are not subject to frequent flooding and scouring.
Vegetation
The wet meadows (wet prairie) component of this group are commonly dominated by short to tall species such as Sedges (Carex spp), Western Wheatgrass (Elymus smithii), Prairie Cordgrass (Spartina pectinata), or Switchgrass (Panicum virgatum). The vegetation of these communities is usually moderate to dense and the dominant vegetation is typically 0.5-1.0 m tall. Forbs can be common, but shrubs are rarely found in this type. In wetter sites, the most abundant species are often Calamagrostis stricta, Carex pellita, Carex sartwellii, Anemone canadensis, Apocynum cannabinum, Symphyotrichum lanceolatum, Eleocharis spp, Juncus arcticus ssp. littoralis, Phalaris arundinacea, Polygonum amphibium, and Schoenoplectus americanus. These wetter sites are similar to G325 Great Plains Freshwater Marsh but have standing water for a much shorter amount of time each year.
Vegetation in marshy habitats is often patchy or zonal and is driven by the depth of standing water or lack thereof across the growing season. Communities dominated by Cattails (Typha sp), Bulrushes (Schoenoplectus spp, Scirpus spp), Sedges (Carex spp), Rushes (Juncus spp), and Spikerushes (Eleocharis spp) are the most common. Species richness can vary considerably among individual marshes and wetlands and is influenced in part by adjacent land use. Heights of common vegetation types mostly vary from 0.5 meter to 2 meters tall. Vegetation communities occurring in marshes are representative of their hydroperiod; some basins dry to bare soil after seasonal flooding, while others will have a variety of wetland types in a zoned pattern depending on seasonal water table depths and salt concentrations (Kudray and Cooper, 2006). In semi-permanent marshes, typical communities may include annuals in the drawdown zone near the upland edge, with sedges (Carex species) down gradient, and Broadleaf Cattail (Typha latifolia) and Hardstem Bulrush (Schoenoplectus acutus) located in the deeper, central portion of the marsh. Beyond the emergent vegetation, floating-leaved hydrophytes may be present in wetter sites with longer inundation periods, including Water Buttercup (Ranunculus aquatilis) and Pondweed (Potamogeton species). Other floating species may be present in shallow water, such as Duckweed (Lemna species), and submergents such as Common Hornwort (Ceratophyllum demersum), Horned Pondweed (Zannichellia palustris), and Common Water-milfoil (Myriophyllum sibiricum).
Sandbar Willow (Salix exigua, Salix interior) is the dominant shrub and often the only woody species present. Other shrubs that may be present include Salix eriocephala (syn S. famelica, S. lutea) and Cornus sericea. Stands can have other woody species such as saplings of Salix amygdaloides and Populus deltoides. The understory is usually moderate to lush but can be sparse if subject to a recent major flood. The herbaceous layer is typically dominated by mid and tall graminoids such as Carex spp., Western Wheatgrass, Switchgrass, Prairie Cordgrass, and Schoenoplectus spp. in wetter areas. Other common herbaceous species include Horsetails (Equisetum hyemale), Xanthium strumarium, Polygonum spp., and Ambrosia artemisiifolia.
In Montana, this group is represented by vegetation communities classified into 7 Alliances and 12 Associations within the National Vegetation Classification. Additional vegetation types may occur, and further review is needed.
Dynamic Processes
Communities in this group are dependent on hydrological factors from groundwater recharge, snow melt, surface flows and rain events during the growing season. Drought cycles, annual fluctuations in precipitation and local changes in hydrology directly affect these sites and will result in changes to the vegetation patterns within these marsh and wetland habitats.
Management
Focus on maintaining hydrology of these sites and minimizing or eliminating on-site impacts should be the primary consideration. Additionally, impacts to and activities on adjacent sites may detrimentally impact these communities via changes in hydrology, nutrient and pollution runoff, or increased chances of spread of invasive species onto these sites.
Restoration Considerations
In marsh habitats where water has been drained or altered, the original hydrology of the system must be restored. If water levels are restored, re-growth and re-colonization from dormant rhizomatous root systems of common marsh species often can occur within a few years. Cattle grazing must be eliminated or controlled to allow regrowth, recolonization and resprouting from existing root systems. Many of the characteristic species found in marsh habitats are rhizomatous, thus exhibiting excellent erosion control properties. In some cases, if hydric soils are heavily altered due to pugging or compaction, addition of organic material may be needed to facilitate vegetation recolonization.
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
Mammals
Birds
Reptiles
Amphibians
Invertebrates
- Other Native Species Occasionally Associated with this Community
Mammals
Birds
Reptiles
Invertebrates
Original Concept Authors
Vinge-Mazer et al. (2025)
Montana Version Authors
S. Mincemoyer
Version Date
7/6/2025
References
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