Wetlands are an extremely important part of the natural world, filled with diverse plant and animal life. In fact, there are more plants and animals living in wetlands than in any other ecosystem in Canada!
Wetlands are important to us humans too; we need and use them to fulfill a variety of purposes. But sometimes our activities harm the wetlands, so it's up to us to do what we can to rebuild them.
What does that mean? Let's take a look.
Wetlands are places where the land is saturated with water for so long that the soil in and around them can't drain and dry out. As a result, they house water-loving plants and other life suited to wet places. Not all wetlands are the same, though. In fact, there are five kinds of wetlands: bogs, fens, marshes, shallow water ponds, and swamps. And all of them are an important part of a healthy water cycle.
But for a wetland to be a useful part of the water cycle, it must be healthy. A healthy wetland ecosystem should have three areas: an aquatic zone (the area below the high water mark), a riparian area (the area around the water where water-loving plants live) and an upland habitat (the driest part of the wetland, where grasses, shrubs, and trees live). Different species will live in these three areas of the wetlands.
In the aquatic zone, where the water levels change regularly, you'll find three types of plants: emergent plants that grow up out of the water, submergent plants that grow below the water, and floating plants that float on top of the water.
The riparian area is the border of moisture-loving plants along the edges of wetlands. The plants are only adapted for occasional flooding. The riparian area has flowers, sedges grasses, shrubs and deciduous trees that like wet soil, like willow and cottonwood poplar.
Finally, in the upland habitat – the driest areas furthest from the wetlands – you'll find trees, shrubs, and grasses that like less moisture than the ones in the riparian area. The uplands also provide important food, nesting cover and shelter for wetland animals.
The three zones of the wetlands (aquatic, riparian and uplands) don't function separately from each other. In fact, it's vital that they all work together to create a healthy ecosystem. That's because the land around the water affects the water itself. So if there is any change or pollution in the uplands, then the riparian will have to work harder to filter out any pollution before it reaches the water and affects the aquatic zone.
Let's look at some of the different parts of the wetland and investigate how they can be impacted and changed by the wetland as a whole.
Emergent plants that grow up out of the water, like bulrushes and cattails, provide habitats for a range of animals. For birds and other animals, they offer shelter from predators, nesting material, and food, and for aquatic invertebrates and fish they provide shelter and food in the parts of the plants under the water. Submergent and floating plants like pondweed, filamentous algae, and water lilies, provide food and shelter for underwater animals such as invertebrates and frogs.
When it is healthy, a wetland will have many different kinds of plants. But as a wetland becomes damaged, the number of plants and the number of types of plants begins to decrease. It's also important to recognize that not all plants help the ecosystem. For example, purple loosestrife is an emergent plant that is an invasive, non-native species, and can cause serious damage to the wetlands.
Aquatic Invertebrates are a necessary food for waterfowl, fish, and other invertebrates and form the base of the food chain. Invertebrates are animals with no backbone, such as insects, worms and snails.
Some aquatic invertebrates can survive in water with more pollution than others. If those pollution tolerant species make up most of the invertebrate species it may mean that the water quality is poor.
The profile (the shape and depth) of a marsh is usually less than 3m deep, but water levels can change for natural reasons (like changes in precipitation or water flow) or because of human actions (like being taken out to be used by industrial or agricultural operations).
However, if water levels drop below 1.5m, it may decrease the number of submergent plants in the wetland, and a water level of less than 0.25 m significantly decreases the diversity of plants and animals in a wetland.
There are a number of different types of measurements to take to assess water quiality, but two of the most important for wetlands are water nutrients and water oxygen levels.
Water nutrients like phosphorus and nitrogen are important for plants in and around the water. However, these nutrients must stay in balance because having too many nutrients is just as bad as having too few. For example, if there are too many nutrients in the water, algae will grow out of control and then die, and when the algae decomposes, a great deal of oxygen is used up.
Because marshes don't usually contain flowing water, oxygen levels are low compared to rivers, but healthy wetlands still need to have enough oxygen for aquatic invertebrates and fish even though many of them can survive with less oxygen than larger and faster animals.
There are a number of different types of birds in the wetlands. In fact, you'll find birds in all of the wetland zones.
Riparian birds and other animals find food and shelter in the plants and shrubs along the shoreline of marshes. Waterfowl (birds that swim and find their food in water) tend to frequent the aquatic zone where they find plants and animals to eat, but they also often need the shelter of the riparian plants for nesting.
One sign of a healthy wetland ecosystem is that it has many kinds of birds in the three different zones.
Wetlands are home to an amazing number of plants and animals. As a result, they have many functions. Let's look at a few.
1. Water resource
Wetlands act like a giant sponge to trap water. When there is a flood, or a lot of rain or snow melting, wetlands can soak up much of it to stop it from damaging our houses and washing away our farm-land. All the plants in a wetland work together to slow down water long enough for it to flow down into the groundwater or evaporate instead of running off the surface into the nearest lake or river. The plants and their roots help to hold the soil together to prevent it washing away (erosion).
Wetlands store water on the surface where we can use it.
2. Life support
Wetlands provide habitat (food, water, shelter, space) for many species. They support many plants and animals that are at risk of becoming extinct.
3. Water quality
Wetlands help to filter out sediment from the water, absorb left-over nutrients, take out chemical pollution, reduce pathogens and clean wastewater.
4. Economic support
Wetlands support hunting, trapping, and fishing businesses by providing habitat for wildlife. They are an excellent environment for growing crops like wild rice. They are a source for peat harvesting. And they support tourism with activities such as photography, canoeing, bird watching, and other wildlife viewing.
5. Social enjoyment/ heritage appreciation/ educational resource
People are drawn to wetlands by their beauty and because so many different animals and plants can be found there. They are also valuable for scientific research and education, providing places for studying plants and animals in their natural setting.
Reclamation is the process of returning changed land to restore its function. Wetland reclamation means creating wetlands either where there was never a wetland or where a wetland was lost or damaged.
Reclaiming a wetland isn't simple though. So when reclaiming a wetland we need to think about all the components that make up a wetland, and we need to ask ourselves: will the new wetland fulfill its function and will it remain a healthy wetland ecosystem over time?
By looking at the effects that different activities will have on the wetland we can make changes that will reclaim lost or damaged wetlands, and return them as close to the way they were as possible. However, for wetland reclamation to work, we need information from a wide range of people. From scientists who work with water, soil, plants and ecology, to construction workers, many people play a key role in reclaiming wetlands. And once a wetland has been reclaimed, we need to continue studying it as it grows to help it become a complete and healthy wetland.