Status and trends of U.S. wetlands and deepwater habitats

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Approximately 215 million acres3 of wetlands existed in the conterminous U.S. at the time of the nation's settlement. By the mid-1970's, 99 million acres remained. The U.S. wetland resource for the 'lower 48' states encompassed 93.7 million acres of palustrine wetland of which 49.7 million were forested, and 5.2 million acres of estuarine wetlands of which 0.5 million were either shrubs, scrub trees or forested. Wetlands now cover about 5% of the land surface, and total wetland acreage amounts to an area roughly the size of California. Half of these wetlands are forested. Annual wetland losses averaged 458 000 acres: 440 000 acres of palustrine losses of which 300 000 are forested, and 18 000 acres of estuarine wetland losses of which less than 1000 acres are shrubs, scrub trees or forested. This annual loss equals an area about half the size of Rhode Island. Of these losses, 66% are forested wetlands. Agricultural development was responsible for 87% of wetland losses and 90% of the losses of forested wetlands. Urban development and other development caused only 8% and 5% of the losses, respectively. Forested-wetland losses caused by urban development and other development were 6% and 4%, respectively. © 1990.

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Forest Ecology and Management