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Seward Park holds one of Seattle's treasures: the Magnificent Forest,
a rare example of an urban lowland old growth forest.
The Magnificent Forest | Birds | Geology | Birds Checklist | Plants Checklist



Osoberry Brother Alfred Brousseau

Forest Composition
Forest Succession
Fungi and the Forest
the Lakeshore
Garry Oak Prairie

While old trees can be found in a few other parks in Seattle, the Magnificent Forest, covering about 120 acres on the northern 2/3 of the Bailey Peninsula, is the largest stand of old trees in the city. Old growth forest is characterized by trees of various ages including large trees >250 years old, by a multi-layered canopy, by standing snags and by large down logs. The Magnificent Forest has these features, but for an old growth forest it is young, with many trees less than 200 years old.

Forest Composition

Pacific Willow catkins
Pacific Willow Bro. Alfred Brousseau

The dominant tree of the Magnificent Forest is Douglas fir. Western red cedar, bigleaf maple and madrona are also well-represented. Western hemlock is found mainly toward the northern end of the peninsula. The shrub understory is composed largely of salmonberry, thimbleberry, elderberry, Indian plum, hazelnut, sword fern, and Cascade Oregon grape. The abundance of madronas, both in the forest and in the developed southern part of the park, indicates a well-drained, relatively dry site. The Bailey Peninsula is one of the few sites in Seattle where bedrock reaches the surface. The shallow soils overlaying the bedrock combined with the topography of the peninsula contribute to good drainage and dryness.

Forest Succession

15,000 years ago the Puget Sound region was covered by the Vashon glaciation. After the ice receded 13,650 years ago, herbaceous plants first became established on the barren glacial debris, and it took about 1,000 years before trees (Douglas firs) became established.

Douglas fir can become established in open sunny locations, but does not grow well in shade, so shade-loving hemlocks and cedars theoretically succeed Douglas fir forests. Drier habitats, however, do not support hemlock and cedar well. In such locations, Douglas fir succeeds itself, depending on natural tree death, storms and wildfire to create openings where seedlings can become established. Tree ring dating on trees cut early this century indicated that the Magnificent Forest was severely burned in the 1490s. The relatively young age of many trees and the presence of burn scars on older trees suggest that it also burned in the early 1800s.

Fungi and the Forest

Conifers and many other trees form associations with mushrooms and other fungi in the soil. Tree roots become coated with fungal mycelium, inhibiting the growth of the root hairs that absorb water and nutrients. This does not harm the trees, but rather the fungal coating increases the efficiency with which they can absorb nutrients. The fungi in turn receive sugars from the trees. This mutually beneficial relationship is known as a mycorrhizal association. Different mushrooms and trees vary in the specificity of their choices for mycorrhizal partners. The same tree may have different associated fungi at different stages of its life. Fungal mycelium may connect adjoining trees in a nutrient web.

In addition to their crucial role in forming mycorrhizal associations, fungi perform another indispensable task in forest ecology. The decay of dead wood is carried out mainly by fleshy fungi. While woodpeckers, bark beetles and carpenter ants all contribute to the breakdown of wood, the actual decay is done almost exclusively by wood-inhabiting mushrooms, especially the polypores. These mushrooms have pores rather than gills and their fruiting bodies are often persistent on dead wood, adding a new layer of pores each year. Although decay is slow in northwest forests, the role of these fungi in returning the nutrients locked up in dead wood to the forest ecosystem is a vital one.

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Honeybee taking nectar from ornamental flower
Honeybee Antonio J. Ferreira

The Magnificent Forest is too small and isolated to support many of the animals, plants and fungi that characterize larger old growth forests, but it does provide shelter to mountain beavers, raccoons, deer mice, western screech owls, bald eagles, pileated woodpeckers and dozens of other bird species. Insects, spiders, and other invertebrates abound. The forest was home to mink until they were trapped in 1941, to deer until 1952, and to Douglas squirrels at least until the 1960s. The forest shores are visited by muskrats, beavers, river otters, red-eared turtles, and many kinds of fish and waterfowl.

The Lakeshore

Unlike the forest, the lakeshore is very young. The present shoreline was created in 1916 when the Montlake cut of the Lake Washington Ship Canal was opened, lowering the lake by about 9 ft. Subsequently the shoreline was graded to make the loop road. Ornamental trees such as Lombardy poplar, cherries, catalpa, and others were planted in many places along the shore, but most of the shoreline appears to have revegetated naturally. Both the forest and the marshy areas drained by the lake lowering probably served as sources of seeds. Douglas firs and thimbleberries came from the forest, and Oregon ashes, Sitka willows, rushes, sedges, cattails, and others probably came from nearby wetlands. The new shores also provided opportunity for invasive species such as Himalayan blackberry, reed canary grass, and yellow loosestrife.

The Garry Oak Prairie

Garry oak with oak apple galls, produced by tiny parasitic stingless gall wasps. The galls serve to protect and feed the gall wasp larvae and do not cause measurable harm to the oaks.

Clark’s Prairie

In 1852 E. A. Clark and John Harvey, fresh from the California gold rush, staked adjacent claims and built a cabin just south of here in an area that came to be called Clark’s Prairie. They probably picked this spot because the natural oak prairie or savanna here required less forest to be cleared in order to farm. Evidence of Clark’s Prairie can still be seen in the Garry oaks found in Seward Park and Martha Washington Park, in the local street names Oakhurst and Oaklawn, and in the fire-adapted plants associated with oak ecosystems that are found on the south side of Pinoy Hill in front of you.

Fire Ecology

Oak prairies and savannas are the most threatened ecosystems in western Washington, because cities have been built over them and because of a century of fire suppression. Native Americans maintained these ecosystems against the encroachment of Douglas-fir forests by burning them. Thick-barked Garry oak and other fire-adapted prairie plants survive fires that kill Douglas–firs and hemlocks. Native Americans encouraged prairies because they were rich in game and edible plants, including acorns. An 1861 land survey from this area mentions oaks and describes “deadenings” that suggest active burning by the local Lake People, who may have planted the oaks here.

Fire-Adapted Plants

Camas, distinguished by its blue flowers in spring, was a major prairie food plant for native peoples throughout the west. Camas bulbs were boiled, roasted in pits, or dried and ground into flour for making cakes.

Snowbrush is a fire-adapted species that requires fire to germinate its seeds. Extremely rare in Seattle, a few snowbrush are found scattered on the hillside above you. Snowbrush can fix nitrogen like lichens, legumes or alder, giving it an advantage in re-colonizing burned-over areas after a fire.

Snowbrush or sticky laurel is easily recognized by its sprays of white flowers and its evergreen sticky leaves with three prominent veins.

Poison-oak is uncommon in Seattle but abundant on the south side of Pinoy Hill. It is a fire-adapted species that is unrelated to oaks, but shares their habitat. While most people are highly allergic to it, the California Indians used it in basketry without ill effects. The shiny leaves of three leaflets turn brilliant crimson in the fall.
“Leaflets three, let it be
Berries white, poisonous sight”

Prairie Restoration

In 2007 the Friends of Seward Park received a grant from the Washington Native Plant Society to help restore the understory of Clark’s Prairie in Seward Park, both for habitat enhancement and for public education about Washington’s oak ecosystems. The Friends partnered with Seattle Parks and Recreation, Seward Park Environmental and Audubon Center, sixth grade classes from Orca K-8 School and other volunteers to plant over 200 prairie plants including camas, chocolate lily, Henderson’s shooting star, and Roemer’s fescue. The restored prairie is a focus of educational programs by the Seward Park Environmental and Audubon Center, including long-term monitoring for plant survival and reseeding, and for the return of birds, butterflies, garter snakes, and other prairie animals.

Prepared for the Friends of Seward Park by Paul Talbert.

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