Causes of Palustrine and Estuarine Wetland Losses between 1992 and 1997, by NRCS Region
Description
This map shows wetland loss and reasons for
wetland conversion from 1992 to 1997. The pie
charts indicate the reasons for wetland
conversion. Pies are proportional to the amount
of wetland loss. Nationally, development
accounted for 49% while agriculture accounted
for 26%. Net wetland losses averaged 32.6
thousand acres per year between 1992 and 1997.
Agriculture includes cropland, pastureland,
CRP, and other farmland. Development includes
urban areas and rural transportation land.
Silviculture includes all non-Federal forest
land. Miscellaneous includes rangeland and all
other land uses. 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.
Sources
Source:
National Resources Inventory, 1997
Distributor:
USDA-NRCS-RIAD
Reliability:
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.
Layers
Aggregate Layer:
NRCS Regions
Other Layers Displayed:
State
Definitions
Conservation Reserve Program (CRP):
A Federal program established under the Food
Security Act of 1985 to assist private
landowners to convert highly erodible cropland
to vegetative cover for 10 years. [NMCSP]
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]
Cropland:
A Land cover/use category that includes areas
used for the production of adapted crops for
harvest. Two subcategories of cropland are
recognized: cultivated and noncultivated.
Cultivated cropland comprises land in row crops
or close-grown crops and also other cultivated
cropland, for example, hayland or pastureland
that is in a rotation with row or close-grown
crops. Noncultivated cropland includes permanent
hayland and horticultural cropland. [NRI-97]
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]
Developed land:
A combination of land cover/use categories,
Urban and built-up areas, and Rural
Transportation Land.
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]
Pastureland and Native Pasture:
A Land Cover/Use category of land managed
primarily for the production of introduced or
native forage plants for livestock grazing.
Pastureland may consist of a single species in a
pure stand, a grass mixture or a grass-legume
mixture. Management usually consists of
cultural treatments-fertilization, weed control,
reseeding, or renovation and control of
grazing. (For the NRI, includes land that has a
vegetative cover of grasses, legumes, and/or
forbs, regardless of whether or not it is being
grazed by livestock.) [NRI-97]
Rangeland:
A Land cover/use category on which the climax or
potential plant cover is composed principally of
native grasses, grasslike plants, forbs or
shrubs suitable for grazing and browsing, and
introduced forage species that are managed like
rangeland. This would include areas where
introduced hardy and persistent grasses, such as
crested wheatgrass, are planted and such
practices as deferred grazing, burning,
chaining, and rotational grazing are used, with
little or no chemicals or fertilizer being
applied. Grasslands, savannas,
many wetlands, some deserts, and tundra are
considered to be rangeland. Certain communities
of low forbs and shrubs, such as mesquite,
chaparral, mountain shrub, and pinyon-juniper,
are also included as rangeland.
[NRI-97]
Wetland:
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:
5818
Production Date:
12/12/00
Product Type:
Map
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