Wetlands: Ecosystems Worth Protecting

Wetlands are estimated to cover nearly 10% of Quebec’s territory. These ecosystems, the best-known examples of which are marshes, swamps and peatlands, are teeming with life. And yet, over several generations, they were drained to make way for cities and monoculture fields. They had, and all too often still have, a reputation for hindering development.

In this article, we offer a definition of wetlands, a description of their various ecological functions and an overview of the different types of wetlands.

What is a wetland?

Wetlands are ecosystems with high biodiversity, mainly because they are partly terrestrial and partly aquatic. They therefore offer a wide variety of environmental conditions and various sources of nutrients.

Water may be trapped in a wetland or flood it occasionally. It may be stagnant or flowing.

Wetlands may be man-made or natural. In all cases, they contain vegetation adapted to the presence of water, as well as hydromorphic soils.

In its guide Identification et délimitation des milieux humides du Québec méridional, Quebec’s Ministère de l’Environnement, de la Lutte contre les changements climatiques, de la Faune et des Parcs (MELCCFP) defines wetlands as all sites that are saturated with water or flooded for a period long enough to influence the soil or vegetation components, where these are present.

What are wetlands for?

Wetlands support a multitude of biological processes that help ecosystems function properly. These are the ecological functions of wetlands.

The main ecological functions of wetlands

Among the ecological functions listed in the Government of Quebec’s Act to affirm the collective nature of water resources and to promote better governance of water and associated environments, those that apply most specifically to wetlands are:

• Pollutant filtration
• Sediment retention
• Erosion protection
• Groundwater recharge
• Reduced risk of flooding and drought
• Carbon sequestration
• Mitigation of the impacts of climate change
• Habitat for feeding, shelter and reproduction of various species
• Landscape quality

Types of wetlands found in Quebec

• Pond
• Marsh
• Swamp
• Peatland

Pond

Ponds are natural or artificial bodies of water. They are shallower than lakes, with a depth of less than 2 m when their water level is at its lowest (low-water level). They can nonetheless cover a large area.

Ponds are often found in areas with gentle slopes. The dominant plants are floating or submerged aquatic plants, with no more than 25% emergent plants.

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Marsh

Marshes are dominated by herbaceous vegetation and may have mineral or organic soil. Trees and shrubs, if present, cover less than 25% of the marsh area.

Marshes are often associated with river, riparian and lake areas. Their water level therefore varies considerably with tides, flooding and evapotranspiration. Marshes may be permanently or temporarily flooded.

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Swamp

Unlike marshes, swamps have trees or shrubs over at least 25% of their area. Their soil is generally mineral and poorly drained.

The MELCCFP guide identifies two types of swamps. The riparian swamp is subject to seasonal flooding or has a high water table with water circulation enriched in dissolved minerals. The isolated swamp is fed by runoff or groundwater resurgence.

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Peatland

Peatlands are mainly characterized by their vegetation, which consists of either sphagnum mosses or herbaceous plants. In peatlands, the rate of organic matter production is always higher than its rate of decomposition, which leads to an accumulation of peat. This peat forms an organic soil that can be very deep.

Peatlands are constantly flooded or waterlogged, because the water table is at or slightly below ground level and drainage is poor.

According to the MELCCFP guide, there are two main types of peatlands: ombrotrophic (bog) and minerotrophic (fen). They are distinguished by their water source and dominant vegetation.

Also according to the MELCCFP guide, a peatland may be forested or non-forested (open). In a forested peatland, trees taller than 4 m cover more than 25% of the area.

In addition, peatlands are known for their rich biodiversity and their effectiveness at storing large quantities of carbon.

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Working in wetlands

Given the importance of the ecological services provided by wetlands, several laws and regulations protect them. Before starting work in or near what appears to be a wetland, check with:

• Your municipality
• Your regional county municipality (RCM)
• Quebec’s Ministère de l’Environnement, de la Lutte contre les changements climatiques, de la Faune et des Parcs
• Quebec’s Ministère des Ressources naturelles et des Forêts
• Fisheries and Oceans Canada

Or contact the friendly professionals at Avizo Experts-Conseils.

References

• Identification et délimitation des milieux humides du Québec méridional
• Ministère de l’Environnement, de la Lutte contre les changements climatiques, de la Faune et des Parcs