Fire Regimes in the Klamath-Siskiyou
The forests, woodlands and chaparral of the Klamath-Siskiyou Mountains, like many other ranges in the west, have been sculpted by fire and cleansed by the heat of its flames. For untold millennia fire has danced across the region’s ridges and into its deep canyons, having a profound effect on the region’s natural history, yet the role of fire is still widely misunderstood.
The complexity and diversity of fire effects can be staggering. To make generalizations regarding fire history, fire return intervals and fire intensities in the Klamath-Siskiyou is difficult at best. Soil type, topography and the diversity of vegetation have greatly influenced the effects of fire across the landscape. Historically the influence of anthropogenic fire, or cultural burning by native tribes had a dramatic effect on plant communities, especially at low elevations and around important cultural resources.
Each forest, in fact each stand, has its own personal relationship with fire, making fire ecology an extremely complex and inexact science. Despite these difficulties much is known about the influence of fire and the impacts associated with fire suppression. One way that fire ecologists break down this complexity is by describing the different types of fire as fire regimes. A fire regime is a generalized description of the role fire plays in a specific ecosystem, plus the combined historic influence of fire frequency and fire severity. Most forests and woodlands in the Klamath-Siskiyou can be broken into three main fire regimes.
Low severity fire regime
Historically Native American tribes understood fire regimes—probably better than we do today—and worked to maintain both important cultural resources and productive habitat conditions. Native tribes burned for a variety of reasons in the Klamath-Siskiyou Mountains, including the management of edible and medicinal plants, basketry and cordage materials and the maintenance of open, fire resilient conditions, both to aid in hunting and to attract game. Fire was an integral part of the indigenous subsistence cycle and greatly augmented so-called “natural” lightning ignitions.
Forest composition at low elevations was historically mainly pine, oak and other fire adapted species, with dense Douglas fir forest in the canyon bottoms or north facing slopes. The encroachment of young Douglas fir trees into upland forests on more exposed slopes is a more recent result of fire suppression. The anthropogenic use of fire cleansed the forest of fuel, recycled nutrients and created more open conditions by burning up a large percentage of the regeneration and understory fuel. This frequent disturbance moderated fire severity, deposited mineral ash as fertilizer, opened forest canopies, invigorated native herbaceous communities and encouraged both pine and oak reproduction.
Frequent, low severity fire tends to create forests, woodlands and savannas of broadly spaced trees, which