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Losses and Gains in Palustrine and Estuarine Wetlands between 1992 and 1997

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This map shows wetland losses and gains from 1992 to 1997. Bar charts show the total loss and gain in wetlands acreage for each NRCS region and for the nation. Gain and loss data values are in thousands of acres. Net wetland losses averaged 32.6 thousand acres per year between 1992 and 1997. Wetlands includes palustrine and estuarine wetlands identified using the cowardin system, it does not include deepwater habitats. Shifts between wetlands and other aquatic systems are not considered either gains or losses. Hawaii is included in the West region. Puerto Rico and the U.S. Virgin Islands are included in the Southeast region.

Cautions for this Product:
Shifts between wetlands and other aquatic systems are not considered either gains or losses. The map does not include deepwater habitats or wetlands on Federal Land. Data are not collected on Federal land.


Source: National Resources Inventory, 1997
Distributor: USDA-NRCS-RIAD
NRI sample data are generally reliable at the 95% confidence interval for state and certain broad substate area analyses. Generally, analyses that aggregate data points by smaller geographic areas and/or more specific criteria result in fewer data points for each aggregation and therefore less reliable estimates. NRI maps reflect national patterns rather than site- specific information.


Aggregate Layer: NRCS Regions
Other Layers Displayed: State


Cowardin system:
A classification system of wetlands and deep water habitats of the United States, officially adopted by the U.S. Fish and Wildlife Service (FWS) used to develop wetland data bases. The system was developed by Lewis M. Cowardin of the U.S. Fish and Wildlife Service and others. The five major systems are recognized in the NRI: Estuarine, Lacustrine, Marine, Palustrine, and Riverine. [USFWS]

Deepwater habitat:
Any open water area in which the mean water depth exceeds 6.6 feet in nontidal areas or at mean low water in freshwater tidal areas, or is covered by water during extreme low water at spring tides in salt and brackish tidal areas, or covers the deepest emerging vegetation, whichever is deeper [USFWS]

Estuarine system:
Deepwater tidal habitats and adjacent tidal wetlands that are semienclosed by land but have open, partly obstructed, or sporadic access to the open ocean, and in which ocean water is at least occasionally diluted by freshwater runoff from the land. [USFWS]

Federal land:
A land ownership class designating land that is owned by the Federal Government. It does not include, for example, trust lands administered by the Bureau of Indian Affairs nor Tennessee Valley Authority (TVA) land. No data are collected for any year that land is in this ownership. [NRI-97]

Forest land:
A Land Cover/Use that is at least 10 percent stocked by single stemmed forest trees of any size which will be at least 4 meters (13 feet) tall at maturity. When viewed vertically, canopy cover is 25 percent or greater. Also included are areas bearing evidence of natural regeneration of tree cover (cutover forest or abandoned farmland) and not currently developed for nonforest use. For classification as forest land, an area must be at least one acre and 100 feet wide. [NRI-97]

Palustrine system:
All non-tidal wetlands dominated by trees, shrubs, persistent emergents, emergent mosses, or lichens, and all such wetlands that occur in tidal areas where salinity due to ocean derived salts is below 0.5 percent [U.S.FWS]

Areas that have a predominance of hydric soils and that are inundated or saturated by surface or ground water at a frequency and duration sufficient to support, and under normal circumstances do support, a prevalence of hydrophytic vegetation typically adapted for life in saturated soil conditions. [NFSAM]

Wetland System:
Complex of wetland habitats that share the influence of similar hydrologic, geomorphologic, chemical, or biological factors. [U.S. FWS]

Product Information

Product ID: 5817
Production Date: 12/12/00
Product Type: Map

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