Prairie Fires

By Graduate Research Associate Carl Elliot

Walking through the Douglas fir forests in the mist and rain of the Pacific Northwest does not conjure up thoughts of wildfire. Most people, residents and non-residents alike, picture a Northwest landscape of grand old growth forests standing forever enriched by cool weather and rain. A closer inspection in many forested areas in the Puget lowland reveals that fire did have an influence on the plant ecology and landscape. On the few sites that still support the growth of ancient trees, occasional fire scars can be seen coating the bark and gnarled lower branches of the oldest residents.  The frequency of fires in the Puget lowlands by “natural” causes such as lightning strikes is around one every 500 years.  However, the evidence of fire return times from sites in the San Juan Islands down to South Puget Sound show much more frequent fire intervals.

The most frequent fires in the maritime areas of the Pacific Northwest may have been ignited by First Peoples. Fire was a tool used in numerous ways to secure necessary food and materials. Fire could be managed to herd or see game and promote the growth of the available browse plants. Perennial understory and woodland edge plants such as blackcap raspberries, wild strawberries, blue elderberry, bracken fern, and other food sources would increase in abundance and production in response to fire occurring every five years of so.

The most documented and common use of fire was    found on the landscape of Garry oak woodlands and prairies throughout the Puget basin. The burning practices provided vital resources to “inland groups” of First Peoples who had limited access to Puget Sound waterways and tidelands. The oak woodlands primarily provided acorns and camas bulbs, along with a diverse diet of roots and berries. Anthropological research has documented complex family ownership of distinct oak woodlands, camas fields, nettle and berry patches. These areas were burned yearly and harvest techniques of camas in particular involved cultivation practices to ensure long term fertility and abundance. For an excellent overview of Northwest Coast traditional plant use and cultivation see Keep it Living edited by Douglas Deur and Nancy J. Turner.

The first arrival of European and U.S. agriculturalist brought a drastic change in the use of fire as a tool to produce food. Fires were viewed as destructive and dangerous, and indeed they are, catastrophic fires have been battled throughout the west since the time of the first agricultural settlements. Active fire suppression has had definite consequences to the ecology of the western landscape.   For prairies in the Pacific Northwest in particular, fire suppression created a number of changes that can be seen in prairie plant composition and the density of plant cover. Fire suppression allows Douglas-fir and shrubs to increase in abundance, shrinking the overall landscape of the prairie. The reduction in disturbance increases the dominance of large grasses that reduces nectar and forage plants for insects. In general, without fire the biodiversity of the oak woodland and prairie landscape decreases greatly affecting habitat quality.

Accompanying the suppression of fire, European agriculture and animal husbandry introduced pasture grasses and invasive plants. The introduction of domestic stock reduces the vigor of native bunch grasses and forbs and increases the abundance of invasive grasses and forbs. Invasive plants such as Scot’s broom readily dominate the low fertility prairie soils in the absence of fire. These numerous stressors reduce the biodiversity and habitat quality of prairies throughout the region. Of the remaining remnant prairies less than 1% contains healthy populations of native plants. This change in plant composition has had a drastic impact on the insects and animals that utilize the prairies as habitat.

Restoration ecologists are actively working to restore prairie habitat for numerous threatened and endangered species including the Taylor’s Checkerspot, Mardon Skipper and Puget Blue butterflies, as well as the streaked-horned lark and the diminutive Mazama pocket gopher. The re-introduction of fire is one restoration tool to improve habitat on prairies.  These fires are control burns requiring complex organization and cooperation among numerous State and Federal agencies. The majority of the prairie landscape occurs on Joint Base Lewis McCord (JBLM). In the summer of 2011, JBLM implemented an ambitious program that completed almost 2000 acres of controlled burns. These fires provide dramatic pictures of the changes fire brings to a landscape.

The re-introduction of fire is only the first step in the restoration process. Fire performs well to eliminate invasive woody plants and Douglas-fir trees from the prairie. However, the reduction woody plants create a great amount of bare ground suitable for seed germination. Without active next steps in the restoration process the use of fire may result in a further degraded prairie through the introduction of non-native plants. Many of the native plants are limited in distribution and abundance by the amount of seed or propagules that are left in the remnant prairies. This is where the Sustainable Prisons Project becomes involved. The role of the Conservation Nursery at Stafford Creek Corrections Center is to provide the necessary plants to produce seed that can be distributed after the fire. The native species are grown at the nursery to be planted out in seed beds at JBLM. The seed is then harvested and cleaned to be drilled in or spread across the restored prairies.

There are numerous changes and adaptations that have to occur to make the restoration process a success. Often it seems as if no two prairies go through the same trajectories after restoration, leading to a great amount of uncertainty as to how to restore and measure a healthy habitat.  Questions regarding appropriate sowing rates, effective germination and establishment of native plants; pollination,  noxious weed control and endangered species re-introduction are just a few of the research objectives scientists are working on.. Since prairies require control burns every three to five years, humans will be actively involved in their care for as long as we value the prairie landscape.






  1. SPP Plant Profile: Golden Paintbrush (Castilleja levisecta) « Sustainability in Prisons Project

    […] component of the prairie ecosystem, has also led to the decline of populations (see previous post on Prairie Fires).  The U.S. and Washington Department of Fish and Wildlife are actively reintroducing this species […]

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