Wetlands are lands that are nearly always wet. These lands filter the water that passes through them
removing sediment and contaminants. They help recharge groundwater supplies and hold a large
proportion of near-surface carbon. Wetlands also provide habitat for a great variety of species, particularly
waterfowl.
Distribution of Wetlands in Canada
Canada has one of the largest areas in the world that are covered
by wetlands reflecting about 25% of the world's wetlands. In Canada
there are more than 1.2 million square kilometres of wetlands (127
million hectares) or 14% of Canada's total land area. The distribution
of wetlands varies greatly across Canada.
Wetlands occur across most of Canada and their location usually
depends on local factors, such as drainage, topography and surface
materials. At a national scale, the distribution of wetlands is
best explained on the map by including a thematic map layer showing
geological provinces. It shows that wetlands are commonly found
in the platform (flat-lying areas) particularly in the Interior
Platform areas just south and west of the Canadian Shield's southern
border, and in the Hudson Bay Lowlands lying to the south of the
Hudson and James Bays. Most parts of the Shield have wetlands, but
these are scattered and result from localized factors of terrain
and soils.
The types of wetlands across Canada are described in more detail
in the table below.
Table 1. Features of Wetlands in the Wetland Regions of Canada
Features of Wetlands in the Wetland Regions of canada
| Arctic |
Five
percent
of the land area is covered by wetlands. |
| This
region contains 20% of all Canada's wetlands. |
| Permafrost
plays an important role in wetland development by prohibiting
internal drainage and concentrating available water at
the surface. |
| Subarctic |
Thirty
percent of the region is covered by wetland habitats. |
| The interaction of
excess water, severe climate, and discontinuous permafrost
produce distinctive wetland forms. |
| Part of this region,
the Hudson Bay Lowlands, covers an area larger than Great
Britain. |
| Salt
marshes
constitute 85 to 90% of the Hudson Bay Lowland |
| Boreal
|
On
average, 20% of the land in the Boreal wetland region
is covered by wetlands. |
| Bogs
and fens
are common. |
| Coniferous
and hardwood swamps are prevalent in the southern part
of this region. |
| Delta
marshes are common around large lakes and rivers, notably
the Slave River delta (which is found in Great Slave Lake),
and the Peace-Athabasca delta (located just west of Lake
Athabasca). |
| There
are over 100 000 beaver ponds in the Boreal Region, covering
5 to 10% of its total area. |
| Prairie |
Five
to twenty-five percent of
the Prairie Region is wetland. |
| Common
wetland forms in this area include freshwater marshes,
shallow open waters and saline marshes and individual
pothole marshes. |
| Half
of the migratory birds on the continent pass through this
region and use its wetlands. |
| Temperate |
Five
to fifteen percent
of this region is covered by wetlands. |
| Common
wetland forms are hardwood tree swamps, extensive freshwater
marshes, and saline marshes. |
| Ninety
to ninety-five percent of wetlands along the Lakes Erie
and Ontario shores have been destroyed to enable urban
development and agricultural production. |
| Oceanic |
Wetlands
cover less than 5% of the Pacific part of this region,
but there is a variety of wetland types, including coastal
marshes, forested swamps, and fens. |
| Wetlands
in the Atlantic part of this region are generally small.
These wetlands feature coastal salt marshes behind barrier
beaches and in protected bays, as well as bogs, fens,
and forested swamps. |
| Mountain |
Note
that this region is in two widely-separated parts: most
is in the Western Cordillera, but a small part is in the
Torngat Mountains of eastern Canada. |
| Common
types of wetlands in both parts are floodplain marshes,
potholes and shallow basin marshes in valley bottoms.
The estuarine wetlands in the Fraser River Delta support
the highest densities of over-wintering waterfowl, shorebirds,
and birds of prey anywhere in Canada. |
|
Source: P.D.N. Hebert. Canada's Aquatic Environments. Habitats - Wetlands.
Guelph, Ontario: University of Guelph, 2000.
|
