Pacific Rim Campus

Natural History

Smith Prairie is a small remnant of what was once a much larger series of prairies that stretched from Vancouver Island to Lewis County. It is bordered on the east by Douglas-fir forest, on the north by agricultural land, on the west by old game farm pens, and on the south by degraded prairie converted to exotic grassland. This is the best remaining example of a northern Puget Lowland glacial outwash prairie. The only other site is a one-acre remnant next to a golf course located in Port Townsend. These prairies are rare because they are flat, easy to build on, and contain gravel sought after for construction.

The Puget Sound region was shaped by a succession of three glaciations. Continent-wide ice sheets, 6,000 feet thick came down from the north, sweeping across what is now Canada and the northern United States. The Vashon glacier was the last of the Fraser glaciation which receded about 15,000 years ago, shaping the Puget Sound region. The retreating glacier melted, leaving behind material it had scoured from the landscape on its journey southward. This material became the foundation of our glacial outwash prairie.

The glacial outwash substrate, which is mapped as San Juan coarse sandy loam soil, supports a unique community of plants. It is a very dry environment due to its location within the rain shadow of the Olympic Mountains. Smith Prairie only receives 17 inches of precipitation per year. Most of the water that falls on the prairie quickly drains away in the gravelly soil. The plants that are able to survive under these conditions are uniquely adapted for dry conditions. Grasses are commonly associated with prairies, accounting for approximately 50% of the vegetative cover. Bunch grass, or Idaho fescue (Festuca idahoensis var. roemeri), California danthonia (Danthonia californica), and field woodrush (Luzula campestris) are dominant on glacial outwash prairies. Co-dominant with the grasses is a moss (Rhacomitrium canescens). Other species indicative of these prairies are the common camas (Cammasia quamash var. quamash), Oregon sunshine (Eriophyllum lanatum), harvest brodiaea (Brodiaea coronaria), field chickweed (Cerastium arvense), fine-leaved desert parsley (Lomatium utriculatum), death camas (Zigadenus venenosus), and many others. Some of these plants, for example, the common camas, were used by indigenous peoples for food. Presently, invasive plants have gained a foothold in Smith Prairie. These are plants that are also well adapted to dry conditions. Many are invasive European pasture weeds.

The original, pre-human, plant composition of Smith Prairie is unknown. Area residents have reported that it was a common practice of the indigenous people to burn the prairie to promote the growth of the common camas. The burning probably maintained a community like the one described above, keeping at bay larger shrubs, such as snowberry (Symphoricarpus albus) and nootka rose (Rosa nutkana), and trees, such as Douglas Fir (Pseudotsuga menziesii). The conversion of the prairie to a game farm halted this cycle and has allowed for these shrubs and trees to take over the prairie. The actual remnant glacial outwash prairie is quite small, about 3.5 acres, bordered on all sides by these unwelcome plants. It is probable that the soil underneath the shrubs contains native prairie plant seeds. Burning the area may enable these seeds to germinate, bringing back the native prairie species.

The Au Sable Institute's plan for Smith Prairie involves the removal of non-native species from the prairie, the propagation of present native prairie plant species and the overall expansion of the existing prairie remnants. This will require a great deal of research and work in order to determine how to best manage this unique system. Some options may include prescribed burning, planting and/or reseeding of the native prairie species. Methods will be tested on a small scale to see their success rate. Successful ones will then be expanded upon. It is hoped that over time the prairie will grow and begin to cover the surrounding areas.

Narrative based on study conducted by Au Sable students: Helena Yeatts, Bryan Vroom, and Jeremy Toomey, summer of 1999.

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