Wetlands are a diverse group of ecosystems, defined by the type of vegetation native to them, which is in turn determined by the presence of water. They are found throughout the world, on every continent except Antarctica.
Saturated soil conditions prevail in wetland ecosystems. However, the presence of water can be seasonal as is the case with prairie potholes. Water-loving or hydric soils form the foundation of these habitats. Likewise, the vegetation shares these water-loving properties and can tolerate habitat inundated with water.
Like the species that inhabit them, wetlands are endangered ecosystems. The U.S. Geological Survey estimates that the lower 48 states have lost over 50 percent of their wetlands in the last 200 years due to agriculture, development, and other human disturbances. With the loss of wetlands comes the forfeiture of their benefits.
Flood Protection from Wetlands
The most important benefit of wetlands for people is flood protection. Wetlands act as giant sponges, absorbing flood waters from extreme weather events.
According to the U.S. Environmental Protection Agency (EPA), a single acre of wetlands can hold up to 1.5 million gallons of floodwater. Coastal wetlands offer additional flood protection. These habitats absorb the brunt of storm surges from tropical storms and hurricanes, thus mitigating weather impact.
Wetlands located adjacent to areas prone to flooding or along shorelines also control soil erosion by anchoring the soil in place. Shoreline erosion is a serious problem in the United States. According to the Federal Emergency Management Agency (FEMA), ocean coasts are eroding 1 to 4 feet each year. The potential risk becomes clear when one considers that two-fifths of the world's major cities of 1 to 10 million people are located on or near coastal areas.
Improved Water Quality from Wetlands
In addition to flood control, wetlands have other environmental benefits. Wetlands filter the water entering the environment by cleaning the water of toxins from urban and agricultural runoff.
Contaminants become part of the sediment, removed from the surface water. Trapped in the sediment, they no longer constitute an immediate threat to the environment.
Wildlife Habitat
Wetlands provide vital resources for wildlife, supplying habitat for over one third of the nation's threatened and endangered species. For these species, wetlands are their only habitat. Other species rely on the presence of wetlands even if it is not as exclusive habitat. The majority of North American birds depend upon wetlands at some point during their life for food or nesting habitat.
The value of wetlands lies in the diversity of plants and animals. Despite occupying only five percent of the land surface in the United States, 31 percent of the nation's plant species are found in wetlands.
Wetland ecosystems are often misunderstood and thought of as mosquito factories. Yet, these environments are vital for both wildlife and humans. These ecosystems are ecologically rich, with value that extends beyond their boundaries.
Sources:
U.S. Environmental Protection Agency: "Functions and Values of Wetlands" epa.gov
U.S. Geological Survey: "Wetlands" npwrc.usgs.gov
