Provisional State Rank
This widespread wetland system occurs throughout the arid and semi-arid regions of North America. In Montana, this system is typically found in depressions surrounded by an upland matrix of mixed prairie, shrub steppe, or steppe vegetation. Natural marshes occur in and adjacent to ponds and prairie potholes, as fringes around lakes or oxbows, and along slow-flowing streams and rivers as riparian marshes. Marshes are classified as either seasonal or semipermanent based on the dominant vegetation found in the deepest portion of the wetland; vegetation is representative of the hydroperiod. A central shallow marsh zone dominated by graminoids and sedges characterizes seasonal wetlands, while semipermanent wetlands are continually inundated, with water depths up to 2 meters (6.5 feet) and a deeper central marsh zone dominated by cattails (Typha species) and bulrushes (Schoenoplectus species). Water chemistry may be alkaline or semi-alkaline, but the alkalinity is highly variable even within the same complex of wetlands. Marshes have distinctive soils that are typically mineral, but can also accumulate organic material. Soils characteristics reflect long periods of anaerobic conditions. Dominant vegetation often includes western wheatgrass (Pascopyrum smithii), Northwest Territory sedge (Carex utriculata), Nebraska sedge (Carex nebrascensis), broadleaf cattail (Typha latifolia), and hardstem bulrush (Schoenoplectus acutus). Alkaline marsh communities include western wheatgrass, fresh water cordgrass (Spartina pectinata), and seashore saltgrass (Distichlis spicata).
Herbaceous, depressional, mineral with A horizon greater than 10 cm, aquatic herb, deep water greater than 15 cm, saturated soil
This wetland ecological system occurs throughout western North America. In Montana, this system is found throughout the state from foothill to upper montane elevations.
Ecological System Distribution
Approximately 227 square kilometers are classified as Emergent Marsh 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, GARFIELD, GLACIER, GOLDEN VALLEY, GRANITE, HILL, JEFFERSON, JUDITH BASIN, LAKE, LEWIS AND CLARK, LIBERTY, LINCOLN, MADISON, MCCONE, MEAGHER, MINERAL, MISSOULA, MUSSELSHELL, PARK, PETROLEUM, PHILLIPS, PONDERA, POWDER RIVER, POWELL, PRAIRIE, RAVALLI, ROSEBUD, SANDERS, SILVER BOW, STILLWATER, SWEET GRASS, TETON, TOOLE, TREASURE, VALLEY, WHEATLAND, WIBAUX, YELLOWSTONE
This system is found in environments where precipitation is approximately 25 to 50 centimeters (10 to 20 inches) per year. In Montana, this system is typically found in depressions surrounded by an upland matrix of mixed prairie, shrub steppe, steppe vegetation and forests near the mountains. Natural marshes occur in and adjacent to ponds and prairie potholes, as fringes around lakes or oxbows, and along slow-flowing streams and rivers as riparian marshes. Water chemistry may be alkaline or semi-alkaline, but is highly variable even within the same complex of wetlands. Marshes have distinctive soils that are typically mineral, but can also accumulate organic material. Soils characteristics reflect long periods of anaerobic conditions, with gleying, high organic content, and redoximorphic features. Wetland marshes are classified as either seasonal or semi-permanent based on the dominant vegetation found in the deepest portion of the wetland (Stewart and Kantrud, 1971 and LaBaugh et al., 1996). Vegetation communities occurring in these marsh systems is 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 dependent on seasonal water table depths and salt concentrations (Kudray and Cooper, 2006).
Vegetation communities change according to wet-drought cycles. In seasonal ponds that dry out annually, and in semipermanent wetlands during drought years, buried seeds of both annuals and perennials germinate, covering exposed mud flats (Hansen et al., 1995). In semi-permanent marshes, the drawdown zone is typically dominated by western wheat grass (Pascopyrum smithii) near the upland edge, with Northwest Territory sedge (Carex utriculata) and Nebraska sedge (Carex nebrascensis) as the dominant sedges located down gradient, and broadleaf cattail (Typha latifolia) and hardstem bulrush (Schoenoplectus acutus) located in the deeper, central portion of the marsh. Water sedge (Carex aquatilis) is frequently co-dominant with Northwest Territory sedge. Less commonly, blister sedge (Carex vesicaria) and awned sedge (Carex atherodes) are intermixed with Northwest Territory sedge or occur as co-dominants on similar sites. Beyond the emergent vegetation, floating-leaved hydrophytes may be present in wetter sites with longer inundation periods, including water lilies (Nymphaea species), yellow pondlily (Nuphar species), buttercup (Ranunculus species) 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), mare’s tail (Hippuris vulgaris) and water milfoil (Myriophyllum species).
Seasonal marshes are typically dominated by western wheat grass (Pascopyrum smithii), beaked sedge (Carex utriculata), inflated sedge (Carex vesicaria), Nebraska sedge (Carex nebrascensis), creeping spikerush (Eleocharis palustris), Baltic rush (Juncus balticus) and cattail (Typha latifolia or angustifolia). During wetter years, annuals disappear and marshes become dominated by emergent perennials. Common perennial forbs include common willow herb (Epilobium ciliatum), marsh cinquefoil (Potentilla palustris), Gmelin’s buttercup (Ranunculus gmelinii), greater creeping spearwort (Ranunculus flammula), hemlock water parsnip (Sium suave), willow dock (Rumex salicifolius), field mint (Mentha arvensis), leafy aster (Symphyotrichum foliaceum) and broadleaf arrowhead (Sagittaria latifolia). Fern allies such as water horsetail (Equisetum fluviatile) and field horsetail (Equisetum arvense) often form significant cover within seasonal marshes. Grasses common to marshes include small floating mannagrass (Glyceria borealis), tufted hairgrass (Deschampsia caespitosa), and bluejoint reedgrass (Calamagrostis canadensis).
Seasonal and semi-permanent marshes with more alkaline water chemistry are commonly found throughout central and eastern Montana. Typical species include hardstem bulrush, cattail, common threesquare (Schoenoplectus pungens), alkali bulrush (Schoenoplectus maritimus) and inland saltgrass (Distichlis spicata), red swampfire (Salicornia rubra) and prairie cordgrass (Spartina pectinata) in adjacent drawdown zones. These marsh communities are brackish and support species adapted to saline and alkaline water and soil conditions, similar to Western Great Plains Saline Depression systems.
Typically, riverine marshes subjected to unaltered, seasonal water flow and annual flooding are characterized by zonal vegetation determined by water depth with stands of bulrush (Schoenoplectus species), softstem bulrush (Schoenplectus tabernaemontani), and cattail in deeper water, and manna grass (Glyceria species), water sedge, inflated sedge, water horsetail and common spikerush in shallower water zones. Riverine marshes can be influenced by beaver activity and human caused influences that can change the structure and species richness of these plant communities. Beaver activity can increase species richness and diversify community structure by altering water flow, depth, and organic sediment accumulation.
Alliances and Associations
- (A.1403) (Beaked Sedge, Northwest Territory Sedge) Seasonally Flooded Herbaceous Alliance
- (A.1763) (Waterthread, Slender False Pondweed) Permanently Flooded Herbaceous Alliance
- (A.1984) American White Water-lily - Yellow Pond-lily species Permanently Flooded Temperate Herbaceous Alliance
- (A.1374) Baltic Rush Seasonally Flooded Herbaceous Alliance
- (A.1400) Bluejoint Seasonally Flooded Herbaceous Alliance
- (A.1419) Clustered Field Sedge Seasonally Flooded Herbaceous Alliance
- (A.1431) Common Reed Semipermanently Flooded Herbaceous Alliance
- (A.1433) Common Threesquare Semipermanently Flooded Herbaceous Alliance
- (A.1747) Duckweed species Permanently Flooded Herbaceous Alliance
- (A.1443) Hardstem Bulrush - (Softstem Bulrush) Semipermanently Flooded Herbaceous Alliance
- (A.2501) Inflated Sedge Seasonally Flooded Herbaceous Alliance
- (A.1332) Inland Saltgrass Intermittently Flooded Herbaceous Alliance
- (A.1417) Nebraska Sedge Seasonally Flooded Herbaceous Alliance
- (A.1347) Prairie Cordgrass Temporarily Flooded Herbaceous Alliance
- (A.1818) Red Saltwort Seasonally Flooded Herbaceous Alliance
- (A.1381) Reed Canarygrass Seasonally Flooded Herbaceous Alliance
- (A.1444) Saltmarsh Clubrush Semipermanently Flooded Herbaceous Alliance
- (A.1445) Small Floating Mannagrass Semipermanently Flooded Herbaceous Alliance
Wet-drought year climatic cycles in Montana, often in 10 to 20 year cycles, influence the ecological communities in these systems (Hansen et al., 1995). During this climatic cycle, wetlands go through a dry marsh, regenerating marsh, degenerating marsh and a lake phase that is regulated by periodic drought and deluge (Mitsch and Gosselink, 2000). During drought periods, seeds from annuals and perennials germinate and cover exposed mud flats, but when precipitation floods the depressions, the annuals drown and the perennials survive, regenerating the marsh. Over a series of years, perennials dominate and submersed and floating-leaved hydrophytes return. After a few years of the regenerating phase, emergent vegetation begins to decline and eventually the marsh reverts to an open water system. Muskrats may play an important role in the decline of emergent vegetation in some of these systems. During drought, the drawdown to mudflats is necessary so that emergent vegetation can become reestablished. Flooding, drawdown and the eventual exposure of mud flats drive the water-level vegetation cycle. In saline soil marshes, increase in precipitation during exceptionally wet years can dilute the salt concentration in the soils, allowing for less salt-tolerant species to occur.
Species richness can vary considerably among individual examples and is especially influenced by adjacent land use. Agriculture and forestry operations, when adjacent, may cause nutrient and herbicide runoff.
Changes will occur in the plant communities due to climatic conditions and/or management activities. Draining, ditching or conversion to agriculture and pastureland can alter the hydrology of the system. Moderate to heavy grazing practices can greatly decrease cover of beaked sedge, and cause soil compaction. Invasive and exotic species such as reed canarygrass (Phalaris arundinacea), common reed (Phragmites australis) and Canadian thistle (Cirsium arvense) become established in areas of heavy grazing or other disturbances. Diversion or lateration of seasonal flooding in riverine systems can change the species composition and succesional direction of riverine marsh communities.
In marsh systems 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 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 systems are rhizomatous, thus exhibit 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 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:
- 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);
- Evaluating structural characteristics and distribution of each ecological system 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 ecological system;
- 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.
- 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.
- Native Species Commonly Associated with this Ecological System
- Native Species Occasionally Associated with this Ecological System
Original Concept Authors
Montana Version Authors
- Classification and Map Identifiers
Cowardin Wetland Classification:
National Vegetation Classification Standard:
||Wetland or aquatic bed wetland
||Temporarily, seasonally, semi-permanently or permanently flooded
|Geographically Isolated Wetland
||Shrubland and Grassland
||Temperate and Boreal Shrubland and Grassland
||Temperate and Boreal Freshwater Wet Meadow and Marsh
||Western North America Warm Desert Freshwater Marsh
||Warm Desert Freshwater Shrubland, Meadow and Marsh
|Element Global ID
||CES300.729, North American Arid West Emergent Marsh
9222: North American Arid West Emergent Marsh
- Additional ReferencesLegend: View Online Publication
Do you know of a citation we're missing?
- 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.
- Kudray, G.M. and S.V. Cooper. 2006. Montana's Rocky Mountain Front: Vegetation Map and Type Descriptions. Report to the United States Fish and Wildlife Service. Montana Natural Heritage Program, Helena, Montana. 26 pp. plus appendices.
- LaBaugh, J. W., T. C. Winter, G. A. Swanson, D. O. Rosenberry, R. D. Nelson, and N. H. Euliss. 1996. "Changes in Atmospheric Circulation Patterns Affect Midcontinent Wetlands Sensitive to Climate". Limnology and Oceanography. 41 (5): 864-870.
- Mitsch WJ, Gosselink JG. 2000. Freshwater Marshes. In: Wetlands. 3rd Edition. John Wiley and Sons, Inc. 920 p.
- Stewart, R. E. and H. A. Kantrud. 1971. Classification of natural ponds and lakes in the glaciated prairie region. US Department of the Interior, Fish and Wildlife Service, Resource Publication #92, Washington, D.C.