Functions of Wetlands
Long regarded as wastelands, wetlands are now recognized as important features in the landscape that provide numerous beneficial services for people and for fish and wildlife. Some of these services, or functions, include protecting and improving water quality, providing fish and wildlife habitats, storing floodwaters, and maintaining surface water flow during dry periods. These beneficial services, considered valuable to societies would wide, are the result of the inherent and unique natural characteristics or wetlands.
Wetland functions include water quality, improvement, floodwater storage, fish and wildlife habitat, aesthetics and biological productivity. The value of a wetland is an estimate of the importance or worth of one or more of its functions by the revenue generated from the sale of fish that depend on the wetland, by the tourist dollars associated with the wetland, or by public support for protecting fish and wildlife.
- Water Storage: Wetlands function like natural tubs or sponges, storing water and slowly releasing it. This process slows the water's momentum and erosive potential, reduces flood heights and allows for ground water recharge which contributes to base flow to surface water systems during dry periods. Although a small wetland might not store much water, a network of many small wetlands can store and enormous amount of water. The ability of wetlands to store floodwaters reduces the risk of costly property damage and loss of life – benefits that have economic value to us. For example, the U.S. Army corps of engineers found that protecting wetlands along the Charles River in Boston saved $17 million in potential flood damage.
- Water Filtration: After being slowed by a wetland, water moves around plants, allowing the suspended sediment to drop out and settle to the wetland floor. Nutrients from fertilizer application, manure, leaking septic systems, and municipal sewage that are dissolved in the water are often absorbed by plant roots and microorganisms in the soil. Other pollutants stick to soil particles. In many cases, this filtration process removes much of the water's nutrient and pollutant load by the time it leaves a wetland. Some types of wetlands are so good at the filtration function that environmental managers construct similar artificial wetlands to treat storm water and wastewater.
- Biological Productivity: Wetlands are some of the biologically productive natural ecosystems in the world, comparable to tropical rain forests and coral reefs in their productivity and the diversity of species they support. Abundant vegetation and shallow water provide diverse habitats for fish and wild life. Aquatic plant life flourishes in the nutrient-rich environment, and energy converted by the plants is passed up the food chain to fish, waterfowl, and other wildlife and to us as well. This function supports valuable commercial fish and shellfish industries.
DID YOU KNOW?
- In 1991 wetland-related ecotourism activities such as hunting, fishing, bird watching, and photography added approximately $59 billion to the national economy.
- According to the Pacific Coast Federation of Fishermen's Association, almost $79 billion per year is generated from wetland-dependent species, or about 71% of the nation's entire $111billion commercial and recreational fishing industry in 1997,
- An acre of wetland can store 1-15 million gallons of floodwater.
- The Great flood of 1993 in the upper Mississippi River Basin caused billions of dollars in property damage and resulted in 38 deaths. Historically, 20 million acres of wetlands in this area had been drained or filled, mostly for agricultural purposes. I the wetlands had been preserved rather than drained, much property damage and crop loss could have been avoided.
- Although wetlands keep only about 5% of the land surface in the conterminous U.S., they are home to 31% of our plant species.