August 19, 2009
A Fire Adapted Ecosystem
The Salmon River is part of the coniferous and mixed evergreen forests of the Klamath-Siskiyou region, which are widely recognized for their globally outstanding levels of biodiversity. The watershed lies at an important biological corridor connecting the interior Basin and Range biomes with the Pacific Coast. It is a land of biodiversity superlatives and boasts one of the greatest coniferous tree diversities in the world - a convergence of trees found in both Alaska and Mexico.
In its natural state, the Salmon River watershed is a fire-adapted landscape that has evolved with a relatively frequent recurrence of non-catastrophic wildfires. The average return interval for fires in this ecosystem is 10-25 years. The Salmon River's diverse ecosystem types - mixed hardwood/coniferous forests, coniferous forests, oak woodlands, grasslands, and riparian plant communities--have evolved with fire as a natural process. With naturally-balanced fire and the resulting fuel consumption, wildfires typically did not devastate large areas of the watershed with high-intensity burns, but instead traveled slowly, lower to the ground, and did not damage large areas of soil or consume vast stands of forest. Many components of the ecosystem require fire to maintain their natural balance and species composition.
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How it Starts
The primary causes of fire in this region, both historically and in the present, are lightning and human ignition. Naturally-occurring wildfires are ignited by lightning strikes during infrequent but powerful summer thunderstorms. Noted fire ecologist Jim Agee reports that the Siskiyou Mountains exhibit the highest pattern of lightning occurrence in the Pacific Northwest, with as many as twice the number of lightning ignitions as either the Cascades or Olympics.
Human-caused ignitions are also an important factor in the fire history of the Salmon River. The native tribes of the area used fire as a tool to manage the landscape in order to maintain oak stands, aid in the collection of mushrooms and acorns, clear travel ways, and improve habitat for favored plants and game animals. With Euro-American settlement, burning by Native Americans decreased dramatically. Unlike the more localized and controlled burning done by native tribes, the typical intent of burning by white settlers was to burn off as much vegetation as possible.
Traditional aboriginal burning, uncontrolled European settler burning practices, and a severe fire year in 1910, precipitated the passage of the Weeks Act in 1911. With this act, Congress initiated the policy of systematically and efficiently suppressing forest fires.
Fire Out of Balance
The balance of natural, fuel-reducing fire occurrence was changed with the advent of large-scale fire suppression in the early 1900's. As an unintended result of preventing nearly all natural fires, fuel loads increased throughout the watershed. Ultimately, any fire not suppressed would grow many times its natural potential size as it consumed this additional fuel load. In essence, fire suppression demanded further suppression in order to prevent conflagrations. Logging, road-building, and other activities also significantly increased fuel loads.
Complete suppression is, of course, not possible and the Salmon River watershed began experiencing a series of large, catastrophic wildfires beginning in the second half of the 20th century. It is estimated that more than 70% of the watershed has burned since 1911, with more than half of that having burned since 1977.
A struggle is now in process to bring fire adapted ecosystems back into balance. As evidence of the true consequences of long term fire suppression builds, the policy of rabidly suppressing all fire is gradually giving way to a more measured approach. An array of tactics such as fuels reduction, controlled burning, and wildland fire use are now being employed to gradually reintroduce fire to our long suffering forests.
The SRRC is a participant in and advocate for the use of these techniques to return fire to its natural place in the Salmon River. The wildfires of 2008, which burned approximately 80,000 acres in the Salmon River, were another in a series of large, high impact burns which the watershed has endured in the past several decades. With each incident we learn more about how to live with, use, and control fire in ways that keep both our human and natural communities safe and healthy.
For more information: www.srrc.org
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Salmon River Restoration Council
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TOC for Forest & River News, Summer 2009