The U.S. Fish and Wildlife Service prepares reports on the status and trends of wetlands and deepwater habitats of the conterminous United States on a 10-year cycle, in accordance with the Emergency Wetlands Resources Act of 1986 {16 U.S.C. 3931(a)}.

The most recent report in the series (Dahl and Johnson 1991) evaluated wetland trends for the period from the mid-1970's to mid-1980's. The national study design was such that region-specific -- and in some cases state-specific -- information also could be developed. The present report analyzes data collected for the 10-state Southeast Region of the Fish and Wildlife Service (Fig.1).

Figure 1.
Study area: Southeast Region of the U.S. Fish and Wildlife Service

The design of this regional study consisted of a stratified random sample of 2,204 plots drawn from the national sample of 3,629 plots. Aerial photography from the mid-1970's and mid-1980's (mean dates 1974 and 1983) for each of the plots was analyzed to detect changes in wetlands and deepwater habitat acreage. Changes were determined to be either natural or human-induced. The wetland acreage estimate for the mid-1980's was subtracted from the estimate for the mid-1970's and divided by the nine-year study period for an estimate of average annual net loss.

Results show an estimated 51.2 million acres of wetlands in the 10 Southeast states in the mid-1970's. By the mid-1980's, wetlands were reduced to 48.9 million acres, including 44.6 million acres of freshwater wetlands and 4.3 million acres of estuarine wetlands. The net loss within the region was more than 2.3 million acres, making the average annual net loss approximately 259,000 acres. Nearly all the losses were from freshwater wetlands.

Cat Island, Louisiana
PALUSTRINE FORESTED
© NANCY WEBB

In the mid-1980's, wetlands comprised 16 percent of the regional landscape. By contrast, wetlands covered only 5 percent of the total area of the lower 48 states. Southeast wetlands represented 47 percent of the total wetlands in the conterminous United States. Nearly half of the freshwater wetlands and over three-quarters of the estuarine wetlands of the lower 48 states are in the region. Wetland losses within the Southeast represented 89 percent of the net national losses during this period.

Estuarine (saltwater) wetlands declined by about 1 percent, with an estimated net loss of 50,000 acres. The loss rate for estuarine wetlands was substantially less than estimates for previous decades. However, the estuarine loss did not encompass all coastal wetland losses, because some coastal areas also contain extensive freshwater wetlands that had losses. Most estuarine wetland losses occurred along the northern Gulf Coast, especially in Louisiana. Estuarine wetland acreage remained stable throughout the rest of the region.

Palustrine (freshwater) wetlands showed a net decline of 2.3 million acres (4.8 percent). Over 3.1 million acres of forested wetlands (bottomland hardwoods, cypress sloughs, etc.) were lost or converted to other wetland types. Losses were particularly acute in the Lower Mississippi Alluvial Plain (Louisiana, Mississippi and Arkansas) and in the Gulf-Atlantic Coastal Flats of North Carolina (Fig. 2).

Figure 2.
Map of the physical subdivisions of the Southeast (Hammond 1970).

Palustrine nonvegetated wetlands increased by 400,000 acres. Most of the increase came from conversion of non-wetlands to farm ponds, ponds in residential areas and other small impoundments.

Although urban development increased, the effect on wetlands was relatively small compared to other factors. Wetland conversions to non-wetlands were distributed nearly evenly between agriculture and "other" land, such as forests and barren lands. This is a change from previous decades when agricultural development was the primary cause of wetland loss.