Characteristics of Wetlands

Impact of wetlands

Wetlands perform many essential services that are increasingly vital to global ecosystems -- carbon storage, flood control, maintenance of biodiversity, fish production, and aquifer recharge are all examples of these. Recognizing the exponential significance of these functions is an important beginning step toward worldwide conservation solutions. People can complete every-day activities that can contribute to the conservation of Wetlands.

How the Wetlands are Deteriorating

Tipping the Balance

In the last hundred years, the delicate balance that existed between water, wildlife, and land began to collapse. To prevent flooding and create more "usable" land, engineers started tinkering with the Kissimmee River, Lake Okeechobee, and the Everglades. Canals were built and rivers were channeled to speed up water flow from the Kissimmee River to Lake Okeechobee and from Lake Okeechobee to the Gulf. And canals built south of Lake Okeechobee drained much of the Everglades' water into the Atlantic Ocean. This not only prevented flooding in many areas, but it also caused huge sections of the Everglades to dry up. Farmers planted thousands of acres of sugar cane and other crops on many of the once-thriving wetland areas. Other former wetland areas became pastures for livestock.

As southern Florida became more populated, development crept farther and farther into pristine wetland areas. More flood control measures were initiated, including the building of expensive channels, dikes, and diversions. Much of the rich peatland that had taken hundreds of years to form was drained and turned into farmland. Fertilizers from farms and lawns seeped into Lake Okeechobee, reducing the water quality of the lake.

Water Out of Control

Finally the tinkering took its toll. The Everglades became too wet at times and too dry at other times. Uncontrollable fires raged across the land. Salt water began seeping into freshwater aquifers. And the loss of wildlife was great--from drowned fawns to wood storks that were unable to raise their young. With the water flow out of control and unpredictable, areas that were once gently washed with water were now either bone dry or completely flooded. Many biologists were concerned that the Everglades was so greatly altered that it would never function normally again.

Has the Tide Turned?

In the last few years, many people in southern Florida--including government officials have gained a new respect for their valuable wetland systems. Instead of draining and filling wetland areas, Florida is now taking steps to turn the area back into what it once was by restoring the natural flow of water through the state. In a program called Save Our Everglades, federal, state, and local agencies, along with concerned citizens and private organizations, are working together to buy important wetland areas adjacent to the Everglades, to divert the Kissimmee River back closer to its original river channel, and to limit any future draining and channelization.

Important Services provided by Wetlands

• Wetlands are critical components of watersheds and are essential for ecosystem sustainability. Destruction or degradation of headwater wetlands can have extensive effects on the health and productivity of all the streams, lakes, and rivers downstream (Meyer et al. 2003).

• Wetlands recharge water supplies. In northern glaciated prairies, one hectare of forested wetland overlying permeable soil may release up to 939,500 liters of water per day into groundwater (Hayashi et al. 2003). Wetlands also have the potential to store snowmelt runoff. Destruction of wetlands can reduce groundwater levels. Ewel (1990) has estimated that if 80% of a Florida cypress swamp were drained, the associated groundwater would be reduced by approximately 45%.

• Wetlands stabilize shorelines, retaining sediment and reducing erosion.

• Wetlands act as natural filters that can improve water quality (Kadlec and Knight 1996) and reduce the threat of eutrophication (Mitsch et al. 2001), as well as store large amounts of sediment (Day et al. 2007).

• Wetlands can be carbon sinks, with important implications for global climate change. For example, global peatlands can store between 400 and 500 gigatons (Gt) of carbon (Roulet 2000).

• Wetlands help control floods through the storage of large amounts of water. Wetland restoration in the upper Mississippi River Basin would most likely have stored enough water to accommodate the 1993 floods in the US Midwest (Hey and Philippi 1995).

• Wetlands maintain biodiversity by providing habitat for many animal and plant species The Amazon supports more than 2000 fish species, and even African savanna mammals depend upon wetlands during dry periods (Keddy 2000).

• Wetlands produce consumer products such as fish and shellfish, cranberries, blueberries, rice, and timber, as well as medicines derived from wetland plants. Shrimp production in the Gulf of Mexico, for example, can be related to the area of salt marshes (Turner 1977).

• Wetlands are used for a broad range of consumptive and nonconsumptive recreational activities. In Canada alone, the economic value of nature-related activities in 1996 was estimated to contribute $11 billion to the gross domestic product (Environment Canada 2000), although the proportion of this attributable to wetlands alone is not known.

The breadth of services provided by wetlands is illustrated in table 1. We will discuss three services in more depth: carbon cycling and climate regulation, freshwater supply, and biodiversity maintenance.


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