Wetlands of Louisiana
The wetlands of Louisiana are water-saturated coastal and swamp regions of southern Louisiana.
The Environmental Protection Agency defines wetlands as "those areas that are inundated or saturated by surface or groundwater at a frequency and duration water to support, and that under normal circumstances do support, a prevalence of vegetation typically adapted for life in saturated soil conditions (e.g. swamps, bogs, fens, marshes, and estuaries)." Different kinds of wetland arise due to a few key factors, principally water levels, fertility, natural disturbance and salinity. Around Lake Pontchartrain, for example, these few factors produce wetlands including bottomland hardwoods, cypress swamp, freshwater marsh and brackish marsh. High levels of flooding reduce the abundance of trees, leaving four principle marsh types: saline, brackish, intermediate and fresh
Although these areas make up a very small percentage of the total land found in the United States, southern Louisiana contains 40 to 45 percent of the wetlands found in the lower states. This is because Louisiana is the drainage gateway to the Gulf of Mexico for the Lower Mississippi Regional Watershed. The Lower Mississippi Regional Watershed drains more than 24 million acres (97,000 km2) in seven states from southern Illinois to the Gulf of Mexico. Hence the wetlands of this area are important at the national scale.
On the east side of Louisiana, coastal wetlands intergrade with long leaf pine savannas, which support many rare and unusual species such as pitcher plants and gopher tortoises. On the western side, they intergrade with wet prairies, an ecosystem type that was once vast, and now has been all but eliminated. The larger vertebrate fauna such as wolves and bison was exterminated. The eastern coastline of Louisiana is much more susceptible to erosion than the western coastline because much of the eastern coastline was created by silt deposits from the Mississippi River. This natural process of sediment deposition has been blocked by an extensive levee system that directs flood water past wetlands The western coastline is marshy, but the marshes only extend inland by 30 miles (48 km) at the most, then the elevation begins to increase and the marshes fade into solid grounded prairies. Therefore, rising sea levels due to global warming and coastal erosion, may not affect the western coastline as profoundly as it will the eastern half, which may be replaced in open water over substantial areas.
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