What Are Wetlands?
Wetlands are areas of land that are temporarily or permanently submerged or permeated by water.
In Canada, the Canadian Wetland Classification System lists five wetland classes – bog, fen, marsh, swamp, and shallow water.
Bogs are wetlands containing partially decayed plant matter called peat. They store water from and release water to the surrounding land but are not connected to lakes or streams.
The surface of bogs is generally acidic in nature and nutrient-poor, and there is typically at least 40cm of peat present. Bogs usually contain peat mosses, ericaceous shrubs, and black spruce trees.
Fens are similar to bogs, except that they are connected to slow-flowing water such as lakes and streams. As with bogs, the surface water of fens is nutrient-poor, and there is a peat layer of at least 40cm. However, since fens are connected to freshwater, they are more biologically diverse. Common plants and trees include black spruces, tamaracks, sedges, grasses, and mosses.
Marshes are wetlands that are regularly inundated by standing or slowly moving water. As a result, they are nutrient-rich and contain reeds and rushes but few trees. Marshes may also contain well-decomposed peat.
Swamps are similar to marshes, except they are predominantly forested. Like marshes, swamps contain standing or gently moving water and are nutrient-rich. Vegetation generally consists of dense coniferous or deciduous forest or tall shrub thickets.
Shallow Open Water
Shallow open water wetlands are small bodies of standing water, representing the transition between lakes and marshes. The depth of the water is usually less than 2 metres.
What Are The Condition of Canada’s Wetlands?
Canada contains around 1.29 million km2 of wetlands, covering about 13% of the country. However, wetlands used to be significantly more prevalent. Sadly, wetlands have been destroyed in many predominantly urban areas around the country. In southern Ontario, 68% of wetlands have been converted from their natural state to support agriculture and housing. In southwestern Manitoba, only around 25% of the original wetlands remain. However, in the north of the country, almost all wetlands remain intact.
Why is it Important to Conserve Wetlands?
Wetlands contain some of the most diverse ecosystems in the world. They provide a habitat for many unique animals and plants. They also act as spawning grounds for various fish species and provide nesting and foraging opportunities for amphibians, reptiles, birds, insects, and other animals.
For example, in Ontario, over 80 species of fish rely directly on coastal wetlands at some point in their life cycle. Around 50 species depend on them for the entirety of their life cycle. Wetlands in the Canadian prairie landscape also support about 60% of North America’s waterfowl population.
Additionally, more than a third of endangered species in the United States live in wetlands. Many U.S breeding bird populations- including geese, woodpeckers, ducks, hawks, and wading birds – also raise their young in wetlands.
Protection Against Climate Change
Wetlands are carbon ‘sinks’ that contain large amounts of carbon dioxide. Plants growing in wetlands break down and decompose in the waterlogged soil, which traps the carbon dioxide they have absorbed by photosynthesis. Therefore, wetlands lock carbon dioxide into the ground, thus reducing climate change.
By locking the carbon dioxide into the ground, these wetlands slow down climate change. When wetlands are destroyed, the carbon they were storing is released, accelerating climate change.
In addition to sequestering vast amounts of carbon dioxide, wetlands also act as large water filters. In many wetlands, plants and microorganisms absorb chemical runoff from agriculture and industry., therefore purifying the water. Also, plants such as Water Hyacinth and Duckweed, both found in wetlands, can absorb metals such as copper and iron, effectively removing them from water.
Protection from Flooding
Wetlands are also essential for flood mitigation since they reduce the amount of water sent downstream. Wetlands act as natural sponges that trap and slowly release rain, snowmelt, and floodwater, reducing the potential for flooding. Wetland vegetation also slows the flow of water and evenly distributes it across flood plains.
This flood protection is particularly vital in urban areas, where fast flooding can cause immense damage.
What are the Risks to Wetlands?
Arguably the biggest risk to wetlands is invasive species. An invasive species is an organism that “causes environmental or economic harm in a new environment where it is not native.”
Canada’s most widely spread invasive plant is phragmites australis, or European Common Reed, a tall wetland reed that can grow to 6m tall. Phragmites australis arrived in Canada through the St.Lawrence river in 1916 and has spread widely since. It is almost impossible to eradicate as it has rhizomes that send out shoots in all directions below the surface, producing thousands of seeds per plant and creating dense strands that can be difficult to access.
Also, phragmites plants are allelopathic, meaning that they release toxins from their roots, preventing most other plants from surviving in their vicinity. When phragmites take over, they create dead biodiversity zones, uninhabitable for plants and animals, producing no value.
Wetlands are particularly vulnerable to our warming climate. Warmer temperatures and the increased use of water for irrigation reduces the supply of water for wetlands, which leads to a higher concentration of pollutants, such as agricultural chemicals, that settle there. Such high concentrations of contaminants can destroy wetlands and every living organism that lives there.
Also, changes in temperatures can significantly change the plant and animal life of wetlands. For example, changes in precipitation caused by climate change can harm plants and animals that require specific amounts of rain at certain times of the year.
Urban and Agricultural Development
Another important risk to wetlands is urban development. We constantly drain and build upon wetlands to fuel our ever-expanding cities. 50% of the Great Lakes Coastal wetlands, for example, have been lost to urban development. In Toronto, coastal wetlands at the Don river’s mouth were drained and built upon in the early 20th century. Now, a century later, after continual flooding and other issues, the city is spending billions to partly restore them.
Similarly, in rural areas, wetlands are frequently drained to create good farmland. The few wetlands that remain in areas are often so polluted by fertilizers and pesticides that their biodiversity potential is destroyed.
How Can Wetlands be Protected?
Remove Invasive Species
While very difficult, one of the most effective ways to protect wetlands is to remove invasive species such as phragmites australis.
In Ontario, the Nature Conservancy is putting significant effort into eradicating phragmites australis to save wetlands. In a joint initiative with the Ministry of Natural Resources, the organization has been combating the grass in the wetlands, the long point region of Lake Erie. The infestation was so advanced that the only way to remove the ferns was to use a Heath Canada-approved herbicide. As of early 2021, the grass has not been entirely eradicated, but the wetland’s health has improved.
In wetland areas where phragmites australis is not as advanced, it can be controlled or removed by mowing, prescribed burning, hand pulling or mechanical excavation. If you see phragmites australis in Ontario, please report it to the province’s State of Resources department at [email protected].
Wetland Restoration and Creation
If damaged, wetlands can be restored so that they can begin storing carbon once more. This process can include removing invasive species, altering water levels, and planting locally native plants.
Also, new wetlands can be created, although this is a huge undertaking. In 2019, Nature Conservancy Canada created a new 62-acre wetland on Pelee Island in Lake Erie.
Conclusion: It is Very Important to Conserve Wetlands
In conclusion, there are many reasons why it is essential to conserve wetlands. They are vital for biodiversity, purifying water, reducing flooding, and fighting against climate change.
However, once damaged or destroyed, the carbon they were storing is released into the atmosphere and is impossible to recapture. This is why as they continue to be destroyed, we must fight for their protection.