Wetlands are covered with water, either seasonally or permanently. Their ground water table is close to the ground level, which causes the accumulation of water. At the end of summer, the wetlands dry out somewhat, and reach their low level mark.

Aquatic water community:  
Submerged vegetation, floating, and with floating leaves. Water is over 2 metres deep.

Species of plants :
American tapegrass  
Feather pondweed
Pectinate pondweed
Grass-leaved water plantain
Nitella
Chara
Water stargrass
Nuttall’s waterweed
Tuberous water lily
Variegated pond lily
European frogbit
Common duckweed

Marsh :
It consists of wetlands with herbaceous vegetation, submerged to a depth of two metres during Spring floods. Average water level varies from 15 cm to 1 m. If trees and shrubs are present, they cover less than 25% of the surface of the marsh.

Species of plants :
Arrow-leaf
American bullrush
Narrow-leaved cattail  
Floating bur-reed
Aquatic zizania
Flowering rush
Cordate pickerelweed

Wet meadow :    
The vegetation here is of a herbaceous grain-bearing type. In spring, water levels vary between 15 cm et 30 cm. In summer, water is at ground level.

Species of plants :
Reed phalaris
Purple loosestrife
Canada reedgrass
Prairie cordgrass

Swamp :   
Wet, wooded land.Tree or shrub coverage is over 25%. Surface water is stagnant or slow-flowing.

Species of plants :
Silver maple
Red ash
American elm
Cottonwood
Various willow trees

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One-seventh of the surface of Canada is covered by wetlands. One quarter of all the wetlands on Earth can be found in Canada.

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The aquatic plant community occupies a very large part of the surface of Lake Saint-Pierre, because of the lake’s shallow depth.

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Wetland plants absorb the energy of the waves, hold the ground fast through their network of roots, therefore helping to reduce the effects of erosion on the banks.

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By eliminating pollutants (mercury, phosphate, nitrogen), suspended particles, and the surplus of nutrients, vegetation in these environments acts as a real natural filtration plant. Once water has seeped through the plants, it is much clearer, limpid.

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Abundant plant life absorbs CO2 from the atmosphere and transforms it into oxygen, thus playing an important role in preventing global warming.

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Wetlands act like sponges, retaining surplus water during flood periods, and releasing it during dry weather.

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