Maple photo by John F. Williams

wetlands take many forms

This article explores the different types of wetlands found in our region. Our focus is on the types of plants commonly found in each wetland community and the animals you might see there. This is not intended to be a scientific description of wetland types or categories (you can find those in other articles in this issue), but rather a general guide. Keep in mind that different types of wetlands often occur together, creating a mosaic of communities. Also, wetlands change over time, such as when a beaver dam blocks a stream, flooding a forested swamp; the trees eventually die and the forested swamp becomes a pond. Over many years the pond fills with sediment, allowing a shrub wetland to grow in. And so on.

freshwater ponds

Ponds have cattails, sedges, rushes, and even lily pads interspersed with areas of open water. Ponds that have year-round water might support fish such as bass. If the water is still, you will likely find a green layer of duckweed floating on the surface. Waterfowl, from ducks and coots to mergansers, use ponds as nesting spots or places to grab a quick bite along their migratory routes. In late winter, you can often find the egg masses of frogs or salamanders along the shallow margins of a pond, attached to a twig or reed. Dragonflies lay their eggs in ponds, and their larvae mature underwater until emerging as winged adults.

Shrubs such as Douglas spirea and willow may grow around the edge of a pond where the water is shallower. This fringing vegetation provides perches for dragonflies and birds, such as cedar waxwing, that swoop out to capture flying insects over the water. A pond wouldn’t be complete without a great blue heron stalking around its edges.

forested swamps

When you hear the word “swamp” you might think of mossy cypress trees of the South where alligators and water moccasins roam. We have forested swamps in Puget Sound as well, with western red cedar, red alder, Sitka spruce, and black cottonwood being common trees.

It’s not unusual to find a stream meandering through the wetland. For the hiker, forested swamps can be hard to navigate, with pockets of deep, wet soils interspersed with higher hummocks. If you can find one, a boardwalk trail is an ideal pathway through this type of wetland. This terrain creates a unique mosaic where water-lovers, such as skunk cabbage, can be neighbors with upland species like western hemlock.

The dense vegetation of the forest can make it hard to spot wildlife, but you might see or hear signs of deer, racoons, owls, woodpeckers, coyotes, and many other species taking advantage of the hiding places and food sources available in the swamp.

emergent wetlands

 Emergent wetlands lack shrubs or trees, and they are instead dominated by grasses, sedges, rushes, and other ground cover species that “emerge” or poke up from the water. Unlike duckweed, which floats, these plants are rooted in the soil. This type of wetland usually has seasonal flooding in winter and spring, with wet soils but little surface water by summer. A good place to find them is in river floodplains, as well as pastures and ungrazed meadows. Some of the emergent plants, such as creeping buttercup, are widespread and can be found in backyards as well as wetlands. Others, such as spikerush, are particular to wetlands.

The diversity of plants in an emergent wetland can be amazing if you look closely at the seeming tangle of green herbs. The saying “rushes are round and sedges have edges” is good to keep in mind when identifying emergent wetland species. You might find tiny plants such as American brooklime with delicate flowers. Depending on the season, an emergent wetland might support ducks dabbling in early spring ponds, or deer browsing on tender summer grass, or swallows hunting a swarm of insects.

salt marshes

Salt marshes are wetlands along the shores of Puget Sound where the water is saline enough to affect the types of plants that can grow there. In many places a stream or river flows through the marsh into the Sound, diluting the salt and making the water brackish. This is sometimes called an estuarine marsh or marine marsh.

In addition to salinity, the plants of a salt marsh live with the rising and falling of the tide, and each species has a preference for how much salt and how much inundation it can tolerate. For example, some species, such as Puget gumweed and Pacific silverweed, tolerate salt spray but not much tidal inundation; they grow at higher elevations in the marsh. Others, such as Lyngby’s sedge, grow at lower elevations and prefer brackish water.

Other common salt marsh species include pickleweed, fleshy jaumea, fat hen, saltgrass, and seaside plantain. Salt marshes are incredibly important for fish and wildlife, from creatures living in the mud, to young salmon finding a refuge, to bald eagles and great blue herons.

bogs

Bogs form when layers of sphagnum moss grow and die, year after year, creating deep peat soils. They often form in potholes left by the glaciers. The very acidic conditions in a bog support a unique community of plants and animals. These include carnivorous plants, like sundew, that attract and then digest insects to supplement their diet. Other common bog plants include Labrador tea (in the rhododendron family), bog cranberry, sedges, and bog laurel.

Rare plant species and insects, along with more common wildlife, inhabit bogs. Bogs themselves are very rare in our region today. Some were mined for peat and are now open water lakes. Others have been used as discharge points for stormwater, changing their water supply and chemistry so much that the plant communities have been altered.

According to the Washington Department of Ecology, once a bog has been lost it can’t be recreated. The good news is, some remaining bogs have been protected in natural area preserves and other set-aside areas. For more details about local bogs, see King County’s web site.

Table of Contents, Issue #9, Autumn 2020