Puget Sound Lowland Prairies

Ancient oaks stand in a native camas grassland at Fort Lewis's 13th Division Prairie.

These unique grasslands are perhaps the most rare, imperiled and least-known of the ecosystems in western Washington.The purpose of this page is to provide images of these rare environments, most of which survive intact today only behind the fences of Fort Lewis and McChord Air Force Base and at a few small parks and preserves. When the Europeans arrived in the 1840s, our prairies were the easiest terrain to use for farming and building, for they are flat, open country. Many places on today's topographic maps are labeled "prairie", notably in the Tenino area, but most have been significantly altered, so that only the flatness of the land tells you of the environment that once was there.

Fort Lewis: An oasis in suburbia

Camas bloom under the gnarled oaks at 13th Division Prairie.

It's hard to imagine that an Army base could be the largest wilderness in the Puget Sound lowlands, but it's a fact! Set aside in 1917, much of 90,000-acre Fort Lewis has been spared the ravages of our modern world. There are few areas on the base where humans have not set foot, but Army activities have been surprisingly compatible with nature. Unique habitats eradicated elsewhere thrive behind barbed wire and security gates.

Most of Fort Lewis is not open for visitation by the public without advanced permission. The largest native prairie left in Washington, for example, is the 7000-acre artillery impact range (91st Division Prairie)! Curiously enough, decades of explosions from tracer rounds and bombs, along with tank maneuvers, have been a boon to the prairies, for they have kept invasive plants from taking over. Scotch broom, an insidious invader from Europe, has completely choked what used to be prime prairie lands in most other areas. Invasion is also starting to occur at Johnson, Weir (Tenalquot) and 13th Division Prairies, the other large grasslands at the Fort, but in cooperation with the Nature Conservancy, a program of controlled burns and logging of invading Douglas-fir is beginning. Large areas of Scotch broom at 13th Division Prairie have been killed off in the last few years, but it's a constant battle, as each plant can produce thousands of seeds which sprout on the poorest of soils with great success. Additionally, the Army and the Conservancy have worked together to establish Research Natural Areas on the Fort, protecting unique wetlands, white oak woodlands, grasslands and old growth forests. Tank maneuvers are not allowed in these areas, which harbor some of the rarest animals in our state. Many extremely rare plants can be seen on the prairies, too, such as the Oregon whitetop aster at Weir Prairie. Early May is the peak of the most colorful blooming, with camas, buttercup, Oregon lilies, harvest brodiaea, shooting stars, violets and countless others bringing brilliant colors to the native grasslands. It is during this time that several uncommon varieties of butterfly, such as the Mardon skipper and Edith's checkerspot, make their appearance, too. A rare species was just found living on the bombardment range prairie, for example!

How did these prairies get here? They are the legacy of great continental glaciers that plowed through the northern half of Washington over 18,000 years ago. This great carving created Puget Sound and was the genesis of the appearance of the lowlands and foothills we see today. As the great Vashon Glacier receded, its meltwaters poured into what is now south Puget Sound, creating the gigantic Lake Russell. As billions of tons of silt, rock and gravel coursed off the retreating ice, huge outwash plains of deep gravelly deposits were created. Dig a hole in the ground in the Yelm or Lacey area, and you will encounter thousands of these rocks. These soils were poor and drained very quickly, leaving a habitat that specialized plant communities could evolve in, a habitat found nowhere else in the state.

Interestingly enough, pollen records prove that these barren outwash deposits were colonized and then forested for thousands of years by Douglas-fir forests. Then, several thousand years after the glacier had melted, a drier, warmer climate developed in the Puget Sound trough, allowing oak forests and associated plant communities to move north from the Columbia River. The prairies remaining today are a reminder of that drier epoch.

Thousands of years after this, the Natives of our area burned these open lands periodically, keeping them open to increase populations of game animals and of camas, an important food source. In some locations, large Douglas-fir and ponderosa pine survived these fires, leaving strange open parklands of prairie habitat interspersed with the giant trees. Some examples of these "wolf" trees can be seen at Fort Lewis and on the edges of the Mima Mounds Preserve. The Puget Sound prairies of the present, then, are a legacy both of human and geological forces and changes.

The changes we are bringing to the prairies today, however, are much more long-term and detrimental. It's estimated that only 3 percent of the south Sound's prairies remain in a pristine condition, out of some 250,000 acres that existed in pre-settlement times. 85% of all the remaining native Puget Sound grasslands exist behind Fort Lewis's fences, about 20,700 acres. Several of these prairies are well over several thousand acres in size. Perhaps a little more than 3000 acres of functioning prairie exist beyond the military base boundaries, most in widely scattered pockets.

The prairies reach their esthetic peak on the so-called "oak savanna." These are vast areas of native fescue grasses interspersed with groves of Garry oak, also called Oregon white oak. With their gnarled thick trunks, these trees are bizarre indeed in the conifer-dominated landscape of western Washington. They grow very slowly and the largest five-hundred-year-old trees may reach more than six feet in diameter. When heavy limbs break off (which can happen on a totally calm day with no wind), the hollow that is exposed provides hiding and nesting places for dozens of birds and other species. Insects and spiders find oaks to be an advantageous habitat, and some of them are found only on this tree. The best remaining oak savannah is to be found at Fort Lewis and McChord AFB. You can observe beautiful oak stands near Tenino, Oakville and Rainier, and even in Chehalis and Woodland (where the Washington record oak can be found), but their associated prairie ecosystems have been removed by human activities. The endangered western gray squirrel, larger than the introduced eastern grays of our parks and neighborhoods, depends on these oak stands for survival. Over forty of these rare mammals have been found at Fort Lewis, and it's estimated that there are about 200 of them on the base, although these numbers are dropping. The Mazama pocket gopher and related subspecies are also in decline and are making their last stand on intact prairie at the fort and a few dozen areas beyond it, including such unlikely places as the Mason County Corrections Center and the Olympia Airport!

     Western gray squirrel . Photo by Rod Gilbert.                                           Mazama pocket gopher. Photo by Washington
                                                                                                                            Nature Conservancy.

Pierce County has plans to build a new sprawl-inducing highway from Parkland to Steilacoom, slicing through some of the best oak habitat remaining for the squirrels, although with the transportation funding crunch in our state, this project will hopefully not get beyond the planning stage. The squirrels also help distribute acorns, which perpetuate the oak stands, and they feed on the cambial layer of young fir trees, killing them and slowing their invasion of the prairies. Fort Lewis managers and the Nature Conservancy are trying to increase oak habitat through controlled burns, logging of Douglas-fir that have shaded out oak stands and through the planting of seedlings. About 3600 acres of oak woodlands exist today on the Fort, with some more at McChord.

Camas fields at 13th Division Prairie. On their journey through Idaho,
Lewis and Clark mistook distant meadows of camas for lakes.

Fort Lewis has also constructed 400 bluebird nesting boxes, which have been highly successful at increasing the birds' population, so successful, in fact, that some of them have been captured and moved to their former range in the San Juan Islands. Only the Skagit River has a larger number of wintering bald eagles, and threatened or endangered species such as the purple martin, the extremely rare Mazama pocket gopher (recently rediscovered at Fort Lewis), the northern red-legged frog, pileated woodpecker and common loon (now very uncommon) can be found on Fort lands. At McChord Air Force Base, plants believed to be extirpated from the Puget Sound basin, such as Torrey's peavine, have also been rediscovered in rare wetland habitats. In September of 2008, five-hundred juvenile Oregon spotted frogs, a species nearly extinct in the Northwest, was re-introduced to a Fort Lewis lake and wetland complex.

Unlike most wetlands, those of the Fort have been only minimally disturbed. Important lakes and swamps exist in the woods and adjacent to the prairies, Chambers Lake being one of the prettier ones. These areas shelter such rare wildlife. Fort Lewis's wetlands would be an ideal reintroduction location for the endangered Western pond turtle. They have already been released at the nearby South Puget Sound Wildlife Area in Lakewood. The turtles were once common in quiet, stagnant wetland areas, most of which have been altered or destroyed outside the fences of the Fort. (The frog and toad deformities being found across the United States have, unfortunately, touched Fort Lewis in the last few years. Recent evidence points to a fungus introduced into the wild from African clawed frogs used in human pregnancy tests decades ago).

Visitors to the Fort will also notice the anthills! With the large numbers of conifers in the area, there are billions of needles for the ants to collect and incorporate into their nests, which rise like bizarre haystacks in open areas of forest, dozens per acre in places. Some of them are more than four feet high! These strange monuments can be seen easily from the edges of the grasslands.

A Fort Lewis anthill.

The benefits of the Army's new RNAs on the Fort have a double advantage: they are also helping to protect Muck Creek, an important Pierce County fish stream, which has its source on the Fort's lands. Several miles of the stream wind through 13th Division Prairie, with old growth oaks, grand fir and Douglas-fir lining the banks. Oregon ash and cottonwood woodlands can also be found along the creek.

Another unique Fort Lewis landscape is Bower Woods, a ponderosa pine woodland. Ponderosa pine is a well-known species east of the Cascades, but at Fort Lewis, about 2500 acres of these trees exist in a savanna environment. Adapted to a mild, wet climate and emerging in a time when periodic fires burned through the area, the pines are genetically different from their eastern Washington counterparts. Some of the trees are over 250 years old and 150 feet tall. A variety of plants rarely seen in the Puget Sound basin thrive here, including the Puget or deltoid balsamroot, a lovely member of the sunflower family. While other ponderosa pines can be found around Puget Sound, only the groves at the Fort remain in their natural landscape. Bower Woods is also protected as a natural area, and Burlington Northern Railroad has entered into an agreement to protect the pines along its line through the Fort. Giant remnant ponderosas can be seen along Highway 7 in the heavily developed Spanaway area.

A beautiful prairie of Garry oak, Lomatium triternatum and Balsamorhiza deltoidea at training
area 7S at Fort Lewis. This area is not far from Madigan Hospital. (Photo by Van Perdue)

Several highways cross Fort Lewis, and while most, such as I-5, traverse dreary Scotch broom wastelands, some travel through beautiful forests or along the edges of prairies. The Rainier Highway, which runs between that town and Lacey, has one of the few undisturbed lowland forest drives to be found outside of parks in the Puget Sound region, a pretty tour through mature Doug-fir and hemlock, with old growth "wolf" trees here and there. Hopefully, as it manages forest lands on the Fort, the Army will leave this rare landscape undisturbed.

Fort Lewis also owns 2.5 miles of undeveloped Puget Sound shoreline at its northwestern edge, as well as the few undeveloped miles of the Nisqually River between its source in Mt. Rainier National Park and the Nisqually Wildlife Refuge. One significant area along the Nisqually harbors 300-year-old Douglas-fir and the rare sessile trillium (Trillium chloropetalum), and is a protected research area.

At Fort Lewis and McChord Air Force Base, the last, vast areas of un-peopled Puget Sound lowland landscape remain, and only here can you see the landscape as it would have appeared before 1850. Oak forests can be found in the San Juan Islands, Okanogan National Forest and in the eastern reaches of both the Columbia Gorge and south Cascades, but only in the Puget Sound area do they exist in a prairie environment. See a map of Fort Lewis ecosystems.
See a map of Fort Lewis Natural Area Preserves.

Oak savanna at 13th Division Prairie.

Why my interest in these prairie environments? First of all, they are a little-known, incredibly diverse habitat with more colors in the spring than any garden. They harbor unique species and landscapes that have been wiped out in the urban and suburban landscapes that are creeping to the very edge of Fort Lewis and McChord Air Force Base.

My real connection goes back to childhood, however. Our family has had a summer home on Totten Inlet on the south Sound for more than fifty years. I remember from a very young age that turn off of Highway 101 onto Steamboat Island Road, and the slow drive past the massive, gnarled oaks of Schneider Prairie. I wanted to know why those trees were there and not all over the landscape of the state, and why did I see the same trees suddenly in the Tacoma and Olympia areas, but not further north? And what were those pretty purple flowers that exploded from nowhere every May under those old trees?

My curiosity has led me to explore these prairies on my own, which has been a wonderful process of discovery. I also love nature photography, particularly that of landscapes, and the prairies are one of the best photo subjects one could choose! Besides, why travel to Kansas or Oklahoma when our own native grasslands are so diverse and spectacular? (Though buffalo-free!)
Puget Sound's prairies need your help! Many of them are vanishing forever either through sprawl or through neglect. Douglas fir and Scotch broom are swallowing up the unmanaged pieces that remain. By joining a group dedicated to saving these special places, you can do your part. The Nature Conservancy is helping to restore the best pieces that remain and to purchase remaining tracts still worth preserving. In the best of all worlds, many thousands of acres of these habitats would be open space and wildlife habitat, but we've lost that opportunity. The best we can do is save what's left and restore what we can. Once you experience these habitats, you will find them fascinating and worth saving for the future.

This site was last updated on December 18th, 2009. More pictures and content coming soon, including how to make your own prairie habitat at home!

Mt. Rainier dominates the skyline on the prairies.

Go on to Visting Puget Prairie habitats