Classification of Wetlands and Deepwater Habitats of the United States
Regionalization for the Classification System
In this classification system, a given taxon has no particular
regional alliance; its representatives may be found in one or many
parts of the United States. However, regional variations in
climate, geology, soils, and vegetation are important in the
development of different wetland habitats; and management problems
often differ greatly in different regions. For these reasons,
there is a need to recognize regional differences. Regionalization
is designed to facilitate three activities: (1) planning, where it
is necessary to study management problems and potential solutions
on a regional basis; (2) organization and retrieval of data
gathered in a resource inventory; and (3) interpretation of inventory
data, including differences in indicator plants and animals among the
We recommend the classification and map
(Fig. 7) of Bailey
(1976) to fill the need for regionalization inland. Bailey's
classification of ecoregions is hierarchical. The upper four
levels are domain (defined as including subcontinental areas of
related climates), division (defined as including regional climate
at the level of Köppen's  types), province (defined as
including broad vegetational types), and section (defined as
including climax vegetation at the level of K�chler's 
types). On the map, the boundaries between the different levels
are designated by lines of various widths and the sections are
numbered with a four-digit code; digits 1 through 4 represent the
first four levels in the hierarchy. The reader is referred to
Bailey (1976, 1978) for detailed discussion and description of the
units appearing on his map, reproduced in our
The Bailey system terminates at the ocean, whereas the present
wetland classification includes Marine and Estuarine habitats.
Many workers have divided Marine and Estuarine realms into series
of biogeographic provinces (e.g., U.S. Senate 1970; Ketchum 1972).
These provinces differ somewhat in detail, but the broader
concepts are similar.
Figure 7 shows the distribution of 10 Marine
and Estuarine provinces that we offer for North America.
Use of Bailey's sections for the Riverine, Lacustrine, and
Palustrine Systems and the Provinces defined above for the Marine
and Estuarine Systems provides a regional locator for any Wetland
in the United States.
- Arctic Province extends from the southern tip of Newfoundland
(Avalon Peninsula), northward around Canada to the west coasts of
the Arctic Ocean, Bering Sea, and Baffin and Labrador basins. It
is characterized by the southern extension of floating ice, the 4°C summer isotherm, and Arctic biota.
- Acadian Province extends along the Northeast Atlantic Coast
from the Avalon Peninsula to Cape Cod and is characterized by a
well developed algal flora and boreal biota. The shoreline is
heavily indented and frequently rocky. It has a large tidal range
and is strongly influenced by the Labrador Current.
- Virginian Province extends along the Middle Atlantic Coast from
Cape Cod to Cape Hatteras. The province is transitional between
the Acadian and Carolinian Provinces. The biota is primarily
temperate, but has some boreal representatives. The Labrador
Current occasionally extends down to Cape Hatteras and winter
temperatures may approach 4°C. The tidal range is moderate.
- Carolinian Province is situated along the South Atlantic Coast
from Cape Hatteras to Cape Kennedy. It contains extensive marshes
and well developed barrier islands. Waters are turbid and
productive. The biota is temperate but has seasonal tropical
elements. The Gulf Stream is the primary influence, and winter
temperatures reach a minimum of 10°C; summer temperatures
are tropical (in excess of 20°C). The tidal range is small
- West Indian Province extends from Cape Kennedy to Cedar Key,
Florida, and also includes the southern Gulf of Mexico, the
Yucatan Peninsula, Central America, and the Caribbean Islands. The
shoreland is usually low-lying limestone with calcareous sands and
marls, except for volcanic islands. The biota is tropical and
includes reef corals and mangroves. Minimum winter temperatures
are about 20°C and the tidal range is small.
- Louisianian Province extends along the northern coast of the
Gulf of Mexico from Cedar Key to Port Aransas, Texas. The
characteristics of the province are similar to those of the
Carolinian, reflecting the past submergence of the Florida
Peninsula. The biota is primarily temperate and the tidal range is
- Californian Province extends along the Pacific Coast from
Mexico northward to Cape Mendocino. The shoreland is strongly
influenced by coastal mountains and the coasts are rocky.
Freshwater runoff is limited. In the southern part volcanic sands
are present; marshes and swamps are scarce throughout the
province. The climate is Mediterranean and is influenced by the
California Current. The biota is temperate, and includes well
developed offshore kelp beds. The tidal range is moderate.
- Columbian Province extends along the northern Pacific Coast from
Cape Mendocino to Vancouver Island. Mountainous shorelands with
rocky foreshores are prevalent. Estuaries are strongly influenced
by freshwater runoff. The biota is primarily temperate with some
boreal components, and there are extensive algal communities. The
province is influenced by both the Aleutian and California
Currents. The tidal range is moderate to large.
- Fjord Province extends along the Pacific Coast from Vancouver
Island to the southern tip of the Aleutian Islands. Precipitous
mountains, deep estuaries (some with glaciers), and a heavily
indented shoreline subject to winter icing are typical of the
coast. The biota is boreal to subArctic. The province is
influenced by the Aleutian and Japanese Currents, and the tidal
range is large.
- Pacific Insular Province surrounds all the Hawaiian Islands. The
coasts have precipitous mountains and wave action is stronger than
in most of the other provinces. The biota is largely endemic and
composed of tropical and subtropical forms. The tidal range is
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