The Environmental Protection Agency describes wetlands as “our vital link between land and water.”
Also referred to as marshes, bogs or swamps, wetlands are among the most diverse and productive of ecosystems, and perform many important functions that benefit both people and wildlife. Wetlands collect and store stormwater, filter and purify that water, provide habitat for birds and other animals, include a wide diversity of specialized plant life, and are often beautiful as well. Wetlands are highly productive natural communities and provide habitat and food resources for a wide range of species. Wetlands have a high level of nutrients and, coupled with the availability of water, they provide ideal habitat for fish, amphibians, shellfish and insects. Additionally, many birds and mammals rely on wetlands for food, water, breeding grounds and shelter.
An area must be inundated or saturated with water at least part of the year to qualify as a wetland. There are several types of wetlands, classified by factors such as salinity, mineral or organic soil type, and the plants and animals found there. For example, there are both salt- and freshwater wetlands. Some wetlands are covered by trees and grasses, others by floating-leaf plants and open water.
To be called a wetland, an area must be filled or soaked with water at least part of the year. Depending on the type of wetland, it may be covered with trees, grasses, shrubs or moss. Some grassy wetlands are actually dry at certain times of the year.
Like the many endangered species that count on this highly variable ecosystem for their survival, wetlands themselves are endangered by development and over-use. They can be drained and paved over for construction, polluted by urban run-off, or stripped of resources for their fish and fuel. With wetlands shrinking around the world, including in the United States, mitigation banking provides an opportunity to counter an unfortunate ecological trend.