Local freshwater wetlands are diverse and abundant throughout
the Columbia Coast. These habitats include fens, which
are complexes of swales and dunes with a variety of
wetlands in the swales, swamps, shrublands, marshes,
sphagnum, seasonal wetlands, wet prairies, riparian
habitats, seeps and springs and wet rock slopes. A few
true bogs with isolated hydrology can also be found
on upland sites. Though local usuage calls both sphagnum
marshes and cranberry farms "bogs," neither
wetland is isolated from groundwater or a true bog in
the hydrological sense.
are dune-swale complexes, found on Clatsop Plains, Long
Beach Peninsula and Twin Harbors beaches. These wetlands
are hydrologically connected by groundwater from swale
to swale. Common wetland species include Nootka reedgrass,
slough sedge, Hooker's Willow, Douglas's aster, western
crabapple, and red alder. Fen complexes contain marshes,
open water areas, swamps, seasonal wetlands and adjacent
upland vegetation. In these areas, upland vegetation
goes through succession from dune grassland to shore
pine forest to Sitka spruce forest to western hemlock.
(See Swamps for details).
in the fens have been severely altered in the past century,
resulting in lower winter water levels and drier summer
surfaces. In addition, filling for development fragmented
and isolated many wetlands, impeding drainage, and with
agriculture and urban development, virtually eliminated
native plant communities by displacement with cultivated
non-native species and weeds.
are too wet to grow conifers, but support a
variety of shrubs, including willows, sweet gale, Douglas's
spirea, western crabapple, bog Labrador tea, bog laurel,
and sedges. They are often important habitats for migratory
warblers and amphibians.
are dominated by grasses, sedges and rushes, with some
shrubby species. They represent either a transitional
stage between young interdunal wetlands and coastal
forest, or a permanently wet site, so wet that trees
cannot establish. Common species include slough sedge,
Sitka sedge, common or soft rush, ladyfern, Douglas
spirea, sweet gale and western crabapple. Spirea and
willows may grow throughout marshes, or only on the
edges. In swales along the ocean, shore pine and willows
rapidly invade marshes, beginning the transition to
marshes are rare, usually found in older marsh sites,
with low growing acid-tolerant plants. Bog Labrador
tea, sedges, creeping bunchberry, and sundew are common
plants. Floating bogs are found in a few places. These
marshes tend to have high species diversity, and to
be restricted to very wet, old marsh sites, such as
on the eastern borders of fens north and south of the
Columbia River. Many low marshes were destroyed in the
past century by changes in hydrology.
true bogs can be found on the Columbia Coast.
These sites are hydrologically isolated from groundwater
by geology, and are dominated by sphagnum moss and acid-tolerant
flowering plants, very similar in composition to sphagnum
marshes in fens.
wetlands / vernal pools are common along the
coast in swales. These interdunal wetlands, with low
growing plants and some open soil, may more correctly
be called vernal pools. They tend to have standing water
in winter, and to be dry in summer. Common species include
a variety of rushes, creeping spearwort, veronica, and
cinquefoil. They are short-lived habitats that soon
vegetate with dense stands of sedges, which in turn
are invaded by willows, shore pine and other species
of coastal swamps.
prairies are low marshes, found on open, sunny
inland sites in river valleys. Often highly disturbed
by ditching and draining for agriculture, they are floristically
related to similar sites in the Willamette - Puget Trough.
Sedges, grasses and a group of unique wetland herbs
are found in these prairies.
Wet rocky slopes can be sites for showy
annuals and perennials, including Nuttall's saxifrage,
frigid shooting star, small-leaved montia, western saxifrage.
Wet slopes on Saddle Mountain grow a wide variety of
Seeps and springs are found on open sunny
slopes and in deep shade. Sunny, open wet sites often
have many flowering species, while those deep in forest
shade will have mosses, liverworts and ferns.
Riparian areas are above the reach of
tides, and include river and stream edges. They grow
a wide variety of plants depending on substrate and
light conditions. Cattails, small-seeded bulrush, slough
sedge and canary reedgrass are common in slower moving
waters. Soft rush, docks, Pacific water parsley
Aquatic habitats are permanently wet,
with free-floating and rooted aquatic plants. Species
include watershield, yellow pond-lily, several pondweeds,
smartweeds, duckweed, cattails, bur-reed, and several
aggressive non-natives, including Brazilian elodea (now
Egeria), purple loosestrife, crisp pondweed and Eurasian
watermilfoil. Many of these species are also found in
backwaters of the Columbia and other rivers.