April 19, 2012
A wetland is the general term we use to describe parts of the landscape where water and land meet and intermingle.
Wetlands include the edges of streams, rivers and lakes, as well as springs and a whole range of soggy lands from sloughs to peat bogs and fens. Although the degree of stability of wetlands varies naturally, all wetlands perform ecological functions, whether they contain water on a seasonal or year-round basis.
“Wetlands of all types are integral components of Alberta’s landscape and play an important role in sustaining healthy watersheds. In turn, wetland health is influenced by a variety of factors including climate, groundwater, surface water, vegetation, soils, and human and animal activity.”
(Government of Alberta, Wetland Consultation Workbook, 2007)
Wetlands provide a great variety of valuable ecological services, including the following:
Approximately one-fifth of Alberta’s landbase is covered in wetlands. In Alberta, wetlands can be divided into two broad categories: peatlands and non-peatlands.
Peatlands, such as bogs and fens, are characterized by their peat-based soils and are found mostly in the forested northern part of the province. In fact, 90 percent of Alberta’s wetlands are peatlands located in the boreal region.
The northern part of Alberta, known as the boreal forest, contains more than 100,000 km2 of bogs and fens, amounting to about 11 percent of Canada’s peatlands. Until very recently, these were considered to have little value except for the production of peat used by gardeners and in industrial filtration. Peatlands are now being recognized as representing unique ecosystems that provide habitat for over 400 species of plants, many of them threatened or endangered. Many wildlife species are associated with peatlands as well, including the endangered woodland caribou. The role these vast peat bogs play in climate stability is just beginning to be understood, and this may be their greatest ecological service.
Non-peatlands, comprising mostly marshes, ponds, swamps, and shallow open water, are found primarily in the more settled Parkland and Prairie Regions of the southern half of the province.
Up to 70 percent of Canadian prairie wetlands have been drained and filled in, mainly to facilitate agriculture. In Alberta, 64 percent of wetlands in the White Area have been lost. The estimated wetland loss in Alberta’s Parkland Region alone is 61 percent. Today we have a better understanding of the vital role wetlands play in maintaining wildlife and ecosystem health and in storing, cleaning, and replenishing vital water supplies. Unaltered wetlands are one of the most cost-effective means of controlling floods and cleaning water.
While there has been some success in restoring prairie wetlands disturbed by agriculture and industrial activities, it is generally acknowledged that a restored wetland does not function as optimally as an original intact wetland. In the Wetland Consultation Workbook, 2007, produced by the Alberta Water Council, it is acknowledged that “it is almost impossible to fully replicate the complexity of a natural wetland ecosystem.” Peat-based wetlands are especially complex. They develop over thousands of years and there is currently scientific consensus that once damaged, they are impossible to restore to their original ecological functionality.
Wetlands are nature’s kidneys, functioning on a broad scale to filter and clean water and to recharge surface and underground water supplies. Cities like Calgary are moving toward retaining and even building wetlands. Wetlands are gaining increasing regard for their ability to settle and clean storm water, which is often very contaminated with dog feces, spilled solvents, paint and oil, salt from winter streets, and so on. Wetlands also provide urban wildlife habitats and enhance city aesthetics.
Prince’s Island Park in downtown Calgary is home to a constructed wetland designed to help filter storm water. Many groups collaborated to build an interpretive trail to help educate Calgarians about the many benefits wetlands provide and what we can all do to reduce the amount of contaminants making their way into the Bow River through the storm sewer system.
The real workers in wetlands are plants, mud bacteria and fungi, and filter feeders like freshwater mussels. Research shows that the plants in healthy wetlands located in agricultural areas can remove up to 92 percent of nitrogen and 95 percent of phosphorous from over-fertilization of fields. While drawing water through their systems, plants chemically alter or filter out many toxins and detrimental chemicals. Bacteria and fungi in wetland muds gradually convert most filtered toxins, except for heavy metals, into benign materials.