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What
is a Wetland?
Inland
Wetlands
Where
are all the Wetlands?
Wetlands
for the Future
People
and Wetlands
Classroom
Activities
Facts
Links
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RIVERINE
WETLANDS
Riverine wetlands
occur along streams, rivers, and irrigation canals throughout the
United States. They are particularly noticeable in western states
such as Idaho because they form ribbons of trees and shrubs in an
otherwise arid landscape. You may have heard of these inland wetlands
by their other name: riparian areas.
Healthy riverine
wetlands play an essential role in maintaining healthy streams and
rivers. They typically support dense vegetation of trees such as
cottonwood and quaking aspen, shrubs such as mountain maple and
red alder, and grasses. These plants help bind the soil of banks,
protect the banks from erosion during floods, and trap additional
sediment from floodwaters. The plants also provide habitat for birds,
amphibians, reptiles, mammals, insects, and fish. For example, birds-from
tiny warblers to majestic bald eagles-use riparian areas for cover
from the weather and for breeding, resting, and foraging sites.
Riparian habitat
represents only about one percent of land in the Intermountain West,
but scientists estimate that as many as eighty percent of birds
and other animals of the West depend on riparian habitats during
all or part of their lives. Like other kinds of wetlands, riverine
wetlands are at great risk from human activity. Continue on to Chapter
Four to learn about the sources of these threats, and some solutions.
Riverine wetlands
benefit young salmon directly, by providing them with shelter during
the start of their lives. Riparian areas continue to benefit salmon
indirectly throughout their lives, by helping to keep streams and
rivers cool and free of sediment. The wetland vegetation shades
the pools along the bank, and it also traps sediments during floods
and binds the banks to prevent erosion. Sediment-free water is essential
to salmon. For example, salmon eggs and alevin (hatchlings) depend
on ample flows of clean water through gravel to bring them air and
food. Sediment can smother the eggs and young salmon, and rob them
of food. Sediment can also trap young salmon upstream and prevent
their migration to the ocean. Likewise, sediment can block adult
salmon downstream and prevent their return to spawning sites.
The wetlands
of estuaries, such as at the mouth of the Columbia River, also provide
essential resting and feeding places for salmon. Young salmon spend
at least a short time in these quiet waters before moving into the
ocean; fall chinook salmon spend months there before beginning their
adult journeys. Returning salmon also may rest briefly in the nutrient
rich waters of the estuaries, consuming one last massive meal before
they journey to their spawning grounds.
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