Advances in Wetland Status and Trends Monitoring Cumulative Error Comparisons

The number of wetlands existing in the United States since colonial settlement has declined rapidly. According to reports by the U.S. Fish and Wildlife Service (Tiner, 1984; Tiner et al., 1994; Wilen and Frayer, 1990; Dahl 1990; Dahl et al., 1991) and the National Wildlife Federation (Feierabend and Zelazny, 1987), it is believed that over 200 million acres of wetlands were present in the conterminous United States in the early 1700’s. Estimates of wetland area made during the 1950’s to 1970’s indicate the numbers have dwindled to somewhere between 86 to 99 million acres. Feierabend and Zelazny (1987) reported that wetland losses have totaled an average of 550,000 acres a year from 1954 to 1974. By the mid-1980’s, total wetland acreage constituted approximately 5.0 percent of the coextensive U.S. (Dahl et al., 1991).