Shallow Emergent Marsh

Ecology and Physical Setting 

This is a broadly defined community type, including many herb-dominated wetlands that are seasonally flooded or saturated. Soils are variable but are mostly shallow mucks or mineral soils with a high organic content. Organic soil deposits are deep in some marshes. As the name implies, these marshes have shallow water, with rooted herbaceous plants emerging from the water. During spring flooding, water depths may be two feet or more, but water levels usually drop by summer, leaving only several inches of water or an exposed soil substrate for most of the growing season. When found in areas with calcareous bedrock, these marshes can be enriched, and can support some species more commonly associated with Rich Fens.

Shallow Emergent Marshes occur in a variety of physical settings and in association with many other wetland types. Along lake and pond shores they can form complex mosaics with other communities, including Deep Bulrush Marshes, Deep Broadleaf Marshes, Cattail Marshes, and Lakeside Buttonbush Swamps. In the floodplains of small streams, Shallow Emergent Marshes are commonly associated with Sedge Meadows, Alluvial Shrub Swamps, and Alder Swamps. Many of our beaver meadows are best classified as Shallow Emergent Marsh and, in these cases, may be in an early successional stage. Early-successional wetlands in abandoned agricultural land often resemble Shallow Emergent Marshes but may ultimately succeed to shrub or forested wetland types. 

Vegetation 

Shallow Emergent Marshes are dominated by a robust growth of grasses, sedges, and herbs. Scattered shrubs may be present but are not dominant. The physical structure of the vegetation and species composition vary from one marsh to another, resulting from differences in hydrology, available seed sources, and other factors. In most Shallow Emergent Marshes, the vegetation grows from low hummocks that barely rise above shallow water, although some plants, such as bur-reeds, are well adapted to growing in permanent shallow water. 

Dominant plants may include bluejoint grass, rice cutgrass, woolgrass, bur-reeds, sweet flag, and tussock sedge. Other common associates include Joe-pye weed, white boneset, blue vervain, flat-topped aster, white turtlehead, Canada mannagrass, and several species of sedges and rushes. Shrubs include meadowsweet, steeplebush, willows, and speckled alder. Scattered red maple saplings are probably the most common tree species present; they seldom reach maturity. 

With additional study of this broadly defined community type it may be possible to refine the classification into several more distinct natural community and successional types, based on vegetation dominants, hydrologic regime, and history of human disturbance. 

Wildlife Habitat

Shallow Emergent Marshes are very important for wildlife. But just as this community is variable in plant species composition, so is it variable in the wildlife habitat it provides. Two important factors affecting wildlife use are the depth and duration of standing water, and the juxtaposition of the Shallow Emergent Marsh with other wetland types and open water. Spring peepers and northern leopard frogs may be found in marshes with only seasonal flooding, while American bullfrogs and green frogs use marshes with permanent water. Muskrats may be found in marshes with more permanent water regimes, and beavers may build dams and lodges if there is an associated stream. Mink hunt along stream and lake shorelines and adjacent marshes for small mammals, small birds, frogs, and aquatic species. Red-winged blackbirds and swamp sparrows are common birds of Shallow Emergent Marshes. A group of species commonly called “marsh birds” nest and feed in these wetlands. These birds include Wilson’s snipe, Virginia rail, least bittern, American bittern, and sora. Shallow Emergent Marshes also provide nesting and feeding habitat for waterfowl, including mallard and blue-winged teal. Northern pike spawn in Shallow Emergent Marshes adjacent to Lake Champlain and other lakes.

The showy flowers in Shallow Emergent Marshes attract many fascinating insects. Harris’ checkerspot is a bright orange and brown butterfly always found near its host plant, flat-topped aster—a common species in Shallow Emergent Marshes. Taiga bluet, a damselfly, and belted whiteface, a dragonfly, are two common species found in grassy marshes and other open wetlands.

Related Communities 

• Sedge Meadow is dominated by one or more species of sedge and typically occurs on permanently saturated organic soils. 
  
   
• Cattail Marsh: Cattails are the dominant plants in these marshes. Cattail Marshes may have longer duration flooding than Shallow Emergent Marshes. 

Conservation Status and Management Considerations 

Shallow Emergent Marshes provide important wetland functions, and they need protection, both through regulation and through education. Many have been converted to agricultural uses or are used for pasture. Non-native invasive plants pose a particular threat to Shallow Emergent Marshes, which often have a history of natural or human disturbance. Purple loosestrife is common in this community, often becoming established in the disturbed soils of wet pastures and spreading to adjacent wetlands. The native strain of reed canary grass was once a component of this community, but today almost all the reed canary grass we see is of European origin. This European strain forms near monocultures in some marshes and produces a dense thatch that limits germination of other species. Research indicates that the ability of this strain to form monocultures is the result of its high genetic diversity (Lavergne and Molofsky 2007). 

Distribution/Abundance 

Shallow Emergent Marshes are found throughout Vermont, and similar communities occur across the Northeast and adjacent Canada.

Characteristic Plants

Shrubs

Occasional Species

Meadowsweet – Spiraea alba

Steeplebush – Spiraea tomentosa

Common pussy willow – Salix discolor

Bebb’s willow – Salix bebbiana

Speckled alder – Alnus incana

Red maple – Acer rubrum

Herbs

Abundant Species

Bluejoint grass – Calamagrostis canadensis

Rice cutgrass – Leersia oryzoides

Woolgrass – Scirpus cyperinus

Black-green bulrush – Scirpus atrovirens

Giant bur-reed – Sparganium eurycarpum

American bur-reed – Sparganium americanum

Tussock sedge – Carex stricta

Occasional to Locally Abundant Species

Joe-pye weed – Eutrochium maculatum

White boneset – Eupatorium perfoliatum

Blue vervain – Verbena hastata

Flat-topped aster – Doellingeria umbellata

Purple-stemmed aster – Symphyotrichum puniceum

White turtlehead – Chelone glabra

Canada mannagrass – Glyceria canadensis

Pointed broom sedge – Carex scoparia

Stipitate sedge – Carex stipata

Fox sedge – Carex vulpinoidea

Hoary sedge – Carex canescens

Bristly sedge – Carex comosa

Nodding bur marigold – Bidens cernua

Water horsetail – Equisetum fluviatile 

Common soft rush – Juncus effusus

Short-tailed rush – Juncus brevicaudatus

Canadian rush – Juncus canadensis

Sweet flag – Acorus calamus

Swamp candles – Lysimachia terrestris 

Swamp milkweed – Asclepias incarnata

Non-Native Invasive Plants

Reed canary grass – Phalaris arundinacea

Purple loosestrife – Lythrum salicaria

Flowering rush – Butomus umbellatus

Phragmites – Phragmites australis ssp. australis

Yellow iris – Iris pseudacorus

Rare and Uncommon Plants

Barbed-bristle bulrush – Scirpus ancistrochaetus

Mild water-pepper – Persicaria hydropiperoides

Tapering rush – Juncus acuminatus

Bristly crowfoot – Ranunculus pensylvanicus

Twig rush – Cladium mariscoides 

Cyperus-like sedge – Carex pseudocyperus

Associated Animals

Spring peeper – Pseudacris crucifer 

Gray treefrog – Hyla versicolor 

Northern leopard frog – Lithobates pipiens

American bullfrog – Lithobates catesbeianus 

Green frog – Lithobates clamitans

Painted turtle – Chrysemys picta

American beaver – Castor canadensis 

Muskrat – Ondatra zibethicus 

Mink – Neovison vison 

Meadow vole – Microtus pensylvanicus

Meadow jumping mouse – Zapus hudsonius

Red-winged blackbird – Agelaius phoeniceus 

Swamp sparrow – Melospiza georgiana 

Wilson’s snipe – Gallinago delicata 

Virginia rail – Rallus limicola 

Mallard – Anas platyrhynchos 

Northern pike – Esox lucius 

Harris’ checkerspot – Chlosyne harrisii

Taiga bluet – Coenagrion resolutum 

Belted whiteface – Leucorrhinia proxima

Rare and Uncommon Animals

Eastern ribbonsnake – Thamnophis sauritus

Common watersnake – Nerodia sipedon

Least bittern – Ixobrychus exilis

American bittern – Botaurus lentiginosus 

Sora – Porzana carolina 

Blue-winged teal – Anas discors 

Green-winged teal – Anas crecca 

Places to Visit 

Victory Basin Wildlife Management Area, Victory, Vermont Fish and Wildlife Department



Abbey Pond, Ripton, Green Mountain National Forest



Ethan Allen Homestead, Burlington, Winooski Valley Park District