Geoscience Reference
In-Depth Information
2.5 Wetland classifi cation
Given the great variety of wetland environ-
ments, many classii cation schemes have been
proposed and utilized over the years. The U.S.
Fish and Wildlife Service developed a hierarchy
that consists of wetland systems, subsystems,
and classes (Table 2-1). At the highest level are
i ve wetland systems (Schot 1999):
• Marine - Open ocean, continental shelf,
including beaches, rocky shores, lagoons,
and shallow coral reefs (Fig. 2-17). Normal
marine salinity to hypersaline water chemis-
try; minimal inl uence from rivers or estuar-
ies. Where wave energy is low, mangroves,
mudl ats or sabkhas may be present.
• Estuarine - Deep-water tidal habitats with
a range of fresh-brackish-marine water
chemistry and daily tidal cycles. Salt and
brackish marshes, intertidal mudl ats, man-
grove swamps, bays, sounds, and coastal
Figure 2-14.
Coontail, also known as hornwort
(
Ceratophyllum demersum
), a submerged wetland
plant. It has stout stems up to 2 m long with featherlike
leaves that grow almost entirely underwater. The long,
ropelike stems drift in slow-moving water of springs
and spring-fed streams. Coontail prefers cool, slightly
alkaline water with a high calcium content (hard
water). Seen here in a shallow spring-fed stream with
watercress in the foreground. Turner Falls, southern
Oklahoma, United States; photo by J.S. Aber.
Figure 2-15.
Zonation of fresh-water marsh vegetation: a) spatterdock
(Nuphar luteum
), b) pickerelweed
(
Pontederia cordata
) and narrow-leaved cattail (
Typha angustifolia
), and c) duckweed (
Lemna minor
). Conneaut
Marsh, northwestern Pennsylvania, United States. View southward with the village of Geneva in the background.
Blimp airphoto by J.S. Aber and S.W. Aber.
