Not all flame's the same: Columbia Plateau

How fire historically shaped the Columbia Plateau

Fire ignited by Indigenous land stewards and lightning was historically the primary factor that shaped the landscapes of the Columbia Plateau before Euro-American settlement in the region. Fire occurred frequently in landscapes dominated by grasslands, as windy conditions helped fire spread through perennial grasses, resulting in better conditions for regeneration of fire-adapted plant species.

Sagebrush and juniper ecosystems experienced fire less frequently, as the lack of dense vegetation meant that fuels to burn and carry fire were limited. Fire, in turn, burned in a patchwork pattern that affected some areas but left other vegetation unburned for periods, making it difficult for fire to spread rapidly across large landscapes.

Forestlands in the foothills of the East Cascades and Blue Mountains experienced frequent, low-severity fires that promoted large, widely spaced trees. These trees would often grow for centuries as fire repeatedly burned off much of the competing vegetation. Indigenous land stewards used fire in all these ecosystems to promote the growth of roots, berries, game and other useful goods that helped sustain their livelihoods and the health of the land. Overall, fire across the Columbia Plateau helped to maintain a diverse landscape with a broad variety of different plant communities.

Changes to the Columbia Plateau fire patterns

Land use change and the introduction of invasive species have been the primary factors in changing how fire burns across the Columbia Plateau. Agricultural lands and human infrastructure now occupy a large amount of the region. Invasive annual grasses have filled in vegetation gaps across much of the undeveloped land, creating continuous fuels across large landscapes that allow fire to spread more readily.

Due to climate change, warmer temperatures have led to longer fire seasons, less snowpack and drier vegetation during fire season. Fire suppression during the last century reduced the amount of fire activity on the landscape, leading to more build-up and continuity of vegetation and dead fuels, altered plant communities and significant expansion of western juniper into areas formerly composed of grasses, forbs and shrubs.

How fire shapes the Columbia Plateau today

Fire has largely been excluded from the Columbia Plateau over the past century, as effective fire suppression practices have kept most fires small. But several factors have led to larger fires in recent years. The presence and spread of highly flammable invasive annual grasses allow fire to rapidly spread across large landscapes. Warmer temperatures have led to longer fire seasons, less snowpack and drier vegetation that is more likely to burn. Lack of periodic fire has resulted in denser and more continuous vegetation and significant expansion of western juniper into rangelands.

With more fuels to consume in these ecosystems, fires burn hotter and longer, resulting in more tree mortality and other negative impacts. Human ignitions are now common in this region, as farm equipment and recreational users inadvertently start fires in the dry summer months. The 2018 Substation Fire is an example of the high risk that fire poses to communities in this region. Close to 80,000 acres of agricultural and high-value recreational areas were burned as the fire moved rapidly across an area near The Dalles.

Many agricultural landowners and managers are now trained in basic fire suppression, and many retrofit their equipment with firefighting gear. This can help to offset the impact of human-caused ignitions, but fires can quickly overwhelm their firefighting capacity in dry, hot and windy conditions.