Swamp, Marsh and Bog

Swamp, Marsh and Bog
Swamps, marshes and bogs, the most common wetland habitats, are similar in having the WATER table at, near or above the SOIL surface or root layer of PLANTS. The most important factors influencing development and maintenance of these wetlands are CLIMATE, mineral nutrient availability, water levels and water flow. Their most obvious distinguishing features are the plant species characteristically found in each and the amount of standing water present.

Swamps

Swamps are wetlands characterized by the presence of TREES growing on silty to organic muck soils. They usually occur along RIVER floodplains and in poorly drained basins. Swamps are often inundated seasonally, or remain continually flooded. Most swamps in North America are found in the southeastern US and in the GREAT LAKES region.

Representative of the swamps of this region is Ontario's Minesing Swamp, a 6000 ha wetland in the Nottawasaga River drainage basin west of Lake Simcoe. It is rich in herbaceous flowering plants and is forested by such common deciduous swamp trees as red MAPLE, black ASH, white ELM and silver maple. Eastern white CEDAR, a CONIFER, is also common in many swamp FORESTS and tends to form dense associations on shallow, wet soils where LIMESTONE is near the surface.

Marshes
Marshes are treeless wetland where lush growths of herbaceous plants (eg, GRASSES, SEDGES, reeds and CATTAILS) predominate. Marshes usually form in quiet shallows of ponds, lakes and rivers, and along sheltered coastlines where mineral nutrients are available. They are highly productive ECOSYSTEMS teeming with life.

Freshwater marshes are abundant and widely scattered across North America. In Canada, the better known freshwater marshes border Lakes St Clair, Erie and Ontario, and the shores of the upper St Lawrence River. Freshwater marshes are also common and extensive in the RED RIVER deltas of Manitoba and in the Peace-Athabasca River delta of northern Alberta.

The prairie pothole region of central North America is a vast area dotted with countless sloughs, ponds and lakes and with abundant marsh vegetation, and the region serves as the most important WATERFOWL nesting area on the continent. About 750 000 km² of this kind of habitat occurs in Canada across southern Manitoba, Saskatchewan and Alberta.

Saltwater marshes are restricted to temperate regions. In North America, they are found mainly along the southern and eastern coastlines from the Gulf of Mexico states to the Maritime provinces. TANTRAMAR MARSH, near Aulac, NB, is a historically famous and important saltwater marsh. Others of particular importance in Canada are found at Kamouraska, in Québec, along the broad low coastline of Hudson Bay and James Bay, and at the Fraser River estuary in British Columbia. In western North America, numerous inland saltwater marshes fringe the shores of saltwater lakes (the remnants of ancient seas) and alkali ponds.

Bogs
Bogs are poorly drained, peat-filled depressions dominated by sphagnum MOSSES, evergreen shrubs of the heather family and conifers such as black SPRUCE and LARCH. The water table, at or near the surface of the living moss layer, may be visible as open pools of water. The extensive cover of sphagnum mosses makes bog waters acidic, preventing the growth of many micro-organisms.

The water in bogs is low in oxygen because there is little water movement to create aeration; and bogs are also relatively cold because of the insulating effect of the surface blanket of moss. As a result, little decay occurs in the accumulating layers of organic debris, which build up as PEAT. Bogs are only one of several kinds of wetlands, called "peatlands," that develop in cool, moist, previously glaciated regions of the Northern Hemisphere.

Bogs are particularly common features of poorly drained regions of the BOREAL FORESTon the Precambrian SHIELD of northern Canada. Bogs south of the boreal forest, such as the Mer Bleue near Ottawa, are remnants of the boreal forest formed after the retreat of the ice sheets formed during the last ICE AGE. Such bogs have remained restricted to the poorly drained sites in which they were formed.

Bogs are also common features in most of Atlantic Canada. They are abundant in Newfoundland. In Nova Scotia they are found from near sea level on Briar Island at the western tip of the province to the heights of the Cape Breton Highlands.

In countries such as Ireland, dried peat has traditionally been used as fuel. Peat moss is also used extensively as a soil conditioner; peat harvesting for this purpose is readily evident along the Trans-Canada Highway in parts of the Gaspé Peninsula of Québec.

See also BIOMASS ENERGY; GROUNDWATER.

Author ERICH HABER

Suggested Reading
C.W. Johnson, Bogs of the Northeast (1985); B. Thomas, The Swamp (1976); P.D. Moore and D.J. Bellamy, Peatlands (1974); W.A. Niering, The Life of the Marsh (1966).

Links to Other Sites
Ducks Unlimited Canada
All Ducks Unlimited organizations conserve, restore and manage wetlands and associated habitats for North America’s waterfowl. These habitats also benefit other wildlife and people.

Wetlands of Ontario
An extensive resource about management of wetland ecosystems. From Environment Canada.

Glossary: Marine Ecology
A glossary of terms related to marine ecology. From the website for the Galveston Bay National Estuary Program in the US.

Hydrology
Did you know that Canada receives more snow than any other country? Click on the topic links in this course guide for scientific information about snow, rain, ice, water, and more. A University of Regina website.

Nova Scotia's Natural History
An online guide to the natural history of various regions in Nova Scotia. From the website for the Nova Scotia Museum of Natural History.

Oak Hammock Marsh Interpretive Centre
A great information source about the natural history and educational programs offered at the Oak Hammock Marsh Interpretive Centre, a major wetland conservation area and one of North America’s birding hotspots.

Marshland: Records of Life on the Tantramar
A virtual exhibition about the history of agricultural development in the northern coastal salt marsh Tantramar region of New Brunswick. From the Mount Allison University Archives.

Coastal Coalition of Nova Scotia
The website for the Coastal Coalition of Nova Scotia, an organization dedicated to the preservation, restoration and sustainable use of Nova Scotia's coastal ecosystems. Check out their interactive map of member associations.

Qu'Appelle Valley
Take a virtual tour of Qu'Appelle Valley to explore the fascinating wildlife and geological history of this picturesque region in southern Saskatchewan. Also provides clear explanations of basic ecological and geological concepts related to the natural features of this area. From the University of Regina.

Flyover Lake Saint-Pierre
Explore this colourful website devoted to the ecology of Lac Saint-Pierre, a UNESCO biosphere reserve. From the Virtual Museum of Canada.

Evidence for Conserving Biofilm for Higher-level Organisms
A summary of research into the importance of conserving biofilm found on mud flats and other aquatic environments. From Environment Canada.