What are Wetlands?

Wetlands are areas where water covers the soil, or is present near the surface of the soil, for varying periods of time during the year. Water saturation (hydrology) largely determines how the soil develops and the types of plant and animal communities living in and on the soil. Wetlands may support both aquatic and terrestrial species. The prolonged presence of water creates conditions that favor the growth of specially adapted plants (hydrophytes) and promote the development of characteristic wetland (hydric) soils.

Wetlands vary widely because of regional and local differences in soils, topography, hydrology, water chemistry, climate, vegetation, and other factors including human disturbance. Wetlands are found from the tundra to the tropics and on every continent except Antarctica. Wetlands come in a variety of forms including: mangrove swamps in Florida; bogs and fens in the Northeast; wet meadows and wet prairies in the Midwest; bottomland hardwood swamps in the South; tidal salt marshes along the Coasts; and even tundra wetlands in Alaska. Many of these wetlands are seasonal and may dry out one or more seasons every year. But even wetlands that appear dry at times for significant parts of the year can provide critical habitat for wildlife adapted to feeding and breeding exclusively in these areas.

Why are Wetlands Important?

Wetlands provide many benefits. They support many species of plants and animals; control flooding; improve water control and quality; moderate the global climate; provide natural products; and enhance recreation and education opportunities.

Support Many Species. Wetlands are among the most biologically productive natural ecosystems in the world and are similar to tropical rain forests and coral reefs in the diversity of species they support. The presence or absence of water during the seasons heavily influences the life cycle of native plants and animals. As plants die, plant leaves and stems break down in the water to form small particles of organic material called detritus. Detritus is food for insects, shellfish, and forage fish, and it provides nutrients for wetland plants and algae. These plants and animals are, in turn, food for larger predatory fish, reptiles, amphibians, birds, and mammals.

Wetlands are vital to the survival of various animals and plants, including threatened and endangered species like the wood stork, Florida panther, and whooping crane. More than one-third of the United States' threatened and endangered species live only in wetlands, and nearly half use wetlands at some point in their lives. For many other species, such as the blue heron, wood duck, and muskrat, wetlands are primary habitats. For others, wetlands provide important seasonal habitats where food, water, and shelter are plentiful, especially during migration and breeding.

Control Flooding. Wetlands often function like natural sponges, storing floodwater and slowly releasing it. Trees, root mats and other wetland vegetation help slow floodwaters. This combined storage and slowing can lower flood heights and reduce the energy of flood-swollen rivers, thereby minimizing damage potential. Wetlands thus reduce the likelihood of flood damage to crops, control the volume of run-off in urban areas and buffer shorelines against erosion.

Improve Water Control and Quality. Once wetlands intercept surface run-off, they retain excess nutrients and some pollutants, thereby reducing sediment that would clog waterways and affect fish and amphibian egg development. In addition to improving water quality through filtering, some wetlands maintain stream flow during dry periods and replenish the groundwater that many Americans depend upon for drinking.

Moderate the Global Climate. Wetlands' microbes, plants, and wildlife are part of global cycles for water, nitrogen, and sulfur. Furthermore, scientists are beginning to realize that atmospheric maintenance may be an additional wetlands function. Wetlands store carbon within their plant communities and soil instead of releasing it to the atmosphere as carbon dioxide, thereby moderating the effects of Global Warming.

Provide Natural Products. Wetlands furnish a wealth of natural products, including fish, timber, wild rice, furs and medicines that are derived from wetland soils and plants. Many of the nation's fishing and shellfishing industries harvest wetland-dependent species; this catch is valued at $15 billion a year. In the Southeast, for example, 96% of the commercial catch and over 50% of the recreational harvest are fish and shellfish that depend on the estuary-coastal wetlands system.

Enhance Recreation, Education and Research. Wetlands have important recreational, historical, scientific, and cultural values. More than half of all U.S. adults (98 million) hunt, fish, birdwatch or photograph wildlife. They spend a total of $59.5 billion annually on these activities. Painters and writers continue to capture the beauty of wetlands on canvas and paper, or through cameras, and video recorders. Other people appreciate these wonderlands through hiking, boating, and other recreational activities.

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