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Wetland Plants and Plant Communities of Minnesota and Wisconsin

II. MARSHES


Marshes are characterized by emergent aquatic plants growing in permanent to seasonal shallow water. Species of shallow, open water communities, as well as those found in sedge meadows and seasonally flooded basins, also occur in marshes. Species of sedge meadows and seasonally flooded basins colonize muskrat lodges, floating mats, and muck soils exposed during droughts or artificial drawdowns. Emergent aquatic plants typically become established and spread when water levels are low or when the marsh substrate is exposed, and then persist when water levels rise. However, if water levels rise too quickly, or rise to levels higher than normal, emergent vegetation may not survive, or may rise to the water surface as floating mats. Muskrats can "eat out" emergent vegetation, creating open water areas within the marsh that favor waterfowl use. Unchecked, however, muskrats can eliminate emergent vegetation, leaving an open water area until the next drought or drawdown allows emergent vegetation to recover.

Marshes are among the most productive of all wetlands for water birds and furbearers, and they can also provide spawning and nursery habitat for some fish species. Birds that use marshes for breeding and feeding include ducks, geese, rails, herons, egrets, terns, and songbirds. Raptors such as the osprey, bald eagle, and northern harrier frequent marshes in search of prey. Important furbearers inhabiting marshes include muskrat and mink. Excellent winter habitat can be provided for upland wildlife, including ring-necked pheasant and eastern cottontail. Marshes can help replenish fish populations in adjacent lakes and rivers by providing spawning habitat, most notably for northern pike and muskellunge.

In addition to providing fish and wildlife habitat, marshes have other functions including floodwater retention, protection of shorelines from erosion, aesthetics, and water quality functions involving the trapping of sediments and assimilation of nutrients.

Marshes in Minnesota and Wisconsin are typically divided into deep and shallow marshes depending on water permanence and depth, and degree of soil saturation during the growing season. Because of the similarity of plant species, the discussion of the individual species occurring in deep and shallow marshes will be combined.

II.A. DEEP MARSHES

Deep marsh plant communities have standing water depths of between 6 inches and 3 or more feet during the growing season (Shaw and Fredine 1971). Herbaceous emergent, floating, floating-leaved, and submergent vegetation compose this community, with the major dominance by cattails, hardstem bulrush, pickerelweed, giant bur-reed, Phragmites, wild rice, pondweeds and/or water-lilies.

A deep marsh plant community
VEGETATION: This deep marsh community includes hardstem bulrush (Scirpus acutus), broad-leaved cattail (Typha latifolia), white water-lily (Nymphaea odorata), yellow water-lily (Nuphar lutea), water shield (Brasenia schreberi), lesser duckweed (Lemna minor), floating-leaved pondweed(Potamogeton natans)coontail (Ceratophyllum demersum) and water milfoil (Myriophyllum sp.).

SOILS: Lacustrine deposits.

HYDROLOGY: Permanently to semi-permanently inundated.

LOCATION: Beaver Dam Lake, Waukesha County, Wisconsin.

II.B. SHALLOW MARSHES

Shallow marsh plant communities have soils that are saturated to inundated by standing water up to 6 inches in depth, throughout most of the growing season (Shaw and Fredine 1971). Herbaceous emergent vegetation such as cattails, bulrushes, arrowheads, and lake sedges characterize this community.

A shallow marsh plant community

VEGETATION: The above shallow marsh is dominated by broad-leaved cattail (Typha latifolia) narrow-leaved cattail (Typha angustifolia), giant bur-reed (Sparganium eurycarpum), giant reed grass (Phragmites australis) and river bulrush (Scirpus fluviatilis). Other species include softstem bulrush (Scirpus validus), lake sedge (Carex lacustris), broad-leaved arrowhead (Sagittaria latifolia), lesser duckweed (Lemna minor), star duckweed (Lemna trisulca), water smartweed (Polygonum amphibium), bulblet water hemlock (Cicuta bulbifera), rice cut-grass (Leersia oryzoides), great water dock (Rumex orbiculatus) and indigo bush (Amorpha fruticosa). During the past ten years, a purple loosestrife (Lythrum salicaria) infestation has slowly expanded in spite of control efforts (removal by hand). It threatens to overtake this highly diverse shallow marsh community and establish a purple loosestrife monotype.

SOILS: Seelyeville muck (Typic Borosaprists), a very poorly-drained soil with an upper organic layer greater than 51 inches in depth (and can be many feet in depth). Landscape position is a backwater lake and marsh complex within the broad valley of the Minnesota River.

HYDROLOGY: This backwater area is primarily groundwater fed, but is also inundated during flood events of the Minnesota River. This particular shallow marsh typically has saturated to inundated soils.

LOCATION: Gun Club Lake, Fort Snelling State Park, Dakota County, Minnesota.

SPECIES ACCOUNTS:

Broad-leaved Cattail (Typha latifolia L.)
Narrow-leaved Cattail (Typha angustifolia L.)
Giant Bur-reed (Sparganium eurycarpum Engelm.)
Hardstem Bulrush (Scirpus acutus Muhl.)
Softstem Bulrush (Scirpus validus Vahl)
River Bulrush (Scirpus fluviatilis (Torrey) Gray)
Three-square Bulrush (Scirpus pungens Vahl.)
Purple Loosestrife (Lythrum salicaria L.)
Pickerelweed (Pontederia cordata L.)
Broad-leaved Arrowhead (Sagittaria latifolia Willd.)
Water Plantain (Alisma subcordatum Raf.)
Water Smartweed (Polygonum amphibium L.)
Giant Reed Grass (Phragmites australis (Cav.) Trin.)
Wild Rice (Zizania aquatica L.)
Giant Manna Grass (Glyceria grandis S. Watson)
Rattlesnake Manna Grass (Glyceria canadensis (Michx.) Trin.)
Lake Sedge (Carex lacustris Willd.)
Slough Sedge (Carex atherodes Sprengel)
Bottlebrush Sedge (Carex comosa Boott)
Porcupine Sedge (Carex hystericina Muhl.)
Soft Rush (Juncus effusus L.)


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