Wetland Types

Wetlands vary in appearance and habitat function depending upon where they are located and what conditions they exist in. Some are very open with large areas of water while others have almost no open water at all. What they have in common is the presence of shallow water that may be invisible because of the density of plant growth. The three types of wetlands found in our area are marshes, swamps and peatlands.

Marshes

The kind of wetland that most people picture is a marsh. This is the most common type of wetland in southern Ontario and in the Hamilton area. Marshes have soils that are less organic than other wetlands and they are characterised by emergent vegetation, examples of which can be found in the wetland plant section.

'Emergent' means coming out of the water: emergent plants have their roots underwater, often rooted in the sediment, and most of their leaves above water, such as cattails (Typha spp.). There is also submergent vegetation, which has its entire mass underwater, and floating vegetation, which has its leaves on the water surface and their roots dangling down below.

Marshes usually have an equal area of open water and vegetation. Marshes are prime duck habitat and also excellent muskrat (Ondatra zibethicus) territory.

These habitats can be found along the shores of the Great Lakes and in sheltered bays such as Cootes Paradise and also along rivers or in other depressions across the broader landscape. They have fluctuating water levels, particularly when they are isolated from large water bodies.

Swamps

Swamps are often associated with the deep southern United States, like the Okefonokee Swamp in Georgia, but we have our own swamps right here in our area. Swamps are forested wetlands and the Hamilton area is one of the best places in Canada to see them. Most of our swamps are dominated by hardwood tree species, in particular Red Maple (Acer rubrum) and Silver Maple (Acer saccharinum). These wetlands can form along lakeshores but are more often found along shallow rivers or in low-lying areas where the soil is not flooded all year long. By combining the properties of forest and wetland together, they make very good habitat for birds in particular. Beverly Swamp and the Valens Conservation Area are excellent places to see these ecosystems.

The rarest wetlands in southern Ontario, peatlands are wetlands where the soil is highly organic because is it formed mostly from incompletely decomposed plants. This soil is called peat and its presence is what defines peatlands. Plant material does not break down very easily in waterlogged conditions and the plants that dominate peatlands, such as Sphagnum mosses (Sphagnum spp.) or sedges (Carex sp.), are especially slow to decompose. In addition, many peatland plants produce chemical compounds that slow decomposition further, particularly the Sphagnum mosses. These non-vascular plants are also known as 'peat mosses' because they form peat soils.

'Vascular plants' have vascular tissue; a layer of tube-like tissue made up of connected cells that allows nutrients and water to be transported through the plant between roots and leaves. In woody plants this layer is found under the bark, while in herbaceous plants the bundle of vascular tubes is in the centre of the stems. Plants that have no vascular tissue are called 'non-vascular plants' and they use other methods to acquire water and nutrients. In peat mosses this involves the surface structure of the moss, which like some fabrics, acts like a wick and retains water. This water can pass into the plant directly through the outer cell layers.

The slow decomposition found in peatlands results in soils that are very old. It can take as much as 1,000 years for a peatland to produce as little as 15 centimetres of peat soil. Incredible! This is why peat is not a renewable resource; it is formed over very long periods of time. One nearby peatland, the Summit Bog at Copetown, is 12,000 years old and has peat soil that is 8 metres deep. This means that, on average, this peat soil has taken 1,000 years to deepen by 65 centimetres. There are two main types of peatlands in southern Ontario, bogs and fens. Both form peat but bogs have no significant inflows or outflows of water while fens receive water from surrounding mineral soil, sometimes resulting in a mix of peatland and marsh vegetation.