Fires Were Common in Rainy Northern Forests

A 500-Year Record of Fire from a Humid Coast Redwood Forest

Fire is an example of a disturbance event that redwoods face.
Fire is an example of a disturbance event that redwoods face.

For years, Steve Norman had been told that the humid forests of coastal Northern California must be too wet to burn. Scientists who research fire acknowledge its power as a tool for reshaping the landscape, but some areas were considered nearly immune to fire. This assumption meant that the damp forests of Del Norte Coast Redwoods State Park remained a blank file in the coastal forest fire records.

Steve Norman, a researcher with the US Forest Service, set out to chart the fire history of redwood forests in Northwestern California, and in the process, he challenged assumptions about the forest itself. His area of study — which is drenched by an astounding 152 to 381 centimeters (60 to 150 inches) of rain each year — was deemed too wet to burn as other forests do. By documenting scars on trees, Norman proved that fires in this area had occurred. Scientists assumed fires happened here as rarely as once every 50 to 600 years; Norman demonstrated that between 1700 and 1850, the intervals between fires varied, but the average length between fires was only 21 years until European settlers brought fire suppression practices.

Norman’s research on northern forest fire patterns led him on a quest to unravel the history of the forest. Lightning strikes could naturally set forests ablaze, but the Tolowa Native American Indians are thought to be the primary source of ignitions in the region before 1850. The Tolowa and similar tribes burned forests annually to encourage a strong harvest of the major food source, acorns, since frequent fires kept down infestations of worms and weevils.

The fire patterns Norman revealed reflect historical records of settlement in Northwestern California. After 1850, most of the studied areas burned less frequently, since fewer Native Americans were present. The dropoff in regular fire scars on redwoods coincides with a cholera epidemic that decimated the Tolowa and other tribes. Early European settlers continued to burn extensively until the 1920s. Recent fire suppression practices are drastically different than those of these settlers.

The patterns of fire damage to redwoods also document changing cultures of fire use in the mid-1800s, reflecting the Euro-American settlement, and even the recent tendency toward fire suppression is apparent in the scarcity of fire scars. Hundreds of years from now, the wildfires and fire management practices of today will be among the stories told by redwood rings.

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