The on-going discussion in the Register Guard about wildfire, and our forests is very important to the Eugene area and Oregon in general. Not to beat a dead horse, but the viewpoints of timber industry representatives tends to ignore much new ecological science and relies on old ideas and/or partial truths. So with that in mind, I am submitting another editorial that I hope provides some more nuance and insight to these issues. The ecological perspective below is likely counter intuitive to most people. For instance, more fuels do not necessary create large fires, and “healthy” forests are those with an abundance of dead trees. However, I hope what I present below starts to help people understand how forests and wildfire really work. — George Wuerthner wuerthner@earthlink.net

…Mr. Dubrasich conflates very different fire regimes into one narrative that inaccurately portrays the causes of recent large blazes as well as the influence that fire suppression may have had on PNW forests. Only the lowest elevation grasslands, oak savannas and ponderosa pine forests tended to burn frequently and contrary to timber industry rhetoric even these forest occasionally burned in stand replacement fires. Fire suppression may have increased fuels in these forests, but since only a small proportion of our woodlands are of this forest type, the influence of fire suppression is greatly exaggerated. The bulk of all forest types in the PNW, including most fir, hemlock, spruce, and other mid-higher elevation forests historically burned infrequently and as mixed or high severity stands replacement fires.

Because of the naturally long interval between fires–often hundreds of years–fire suppression has had a minimum affect on most forests types since they have not “missed” a fire rotation and there is no unusual fuel buildup. This is important because the majority of acreage burned annually occurs in higher elevation, longer fire regime kinds of forest types. Large blazes in these forest types cannot be attributed to fire suppression activities, nor are large stand replacement fires “abnormal” or a sign of “unhealthy” forests as timber industry advocates try to portray.

…The 2002 Biscuit Fire illustrates this finding. Old growth stands and north slopes—the very forest types with the highest fuel loadings and greatest biomass–were the least likely to burn. By contrast younger forests, open savannas of Jeffrey pine and shrub dominated south slopes which had far lower fuel accumulations made up the bulk of acreage charred by the blaze. Another study found that areas that had been “salvage logged” after the Silver Fire and subsequently reburned in the Biscuit Fire had higher fire severity than unlogged stands, even though these stands obviously had far less biomass (fuel) than unlogged stands. The explanation is simple—north slopes and old growth forests retained moisture better–and despite the high fuel loads, are more difficult to burn. By contrast, open forests and south slopes exposed to the sun dry out sooner and typically had more “fine” fuels, thus burn better.

This is one reason why “thinning” can enhance the chances that a stand will burn because removing trees opens up the forest to higher solar radiation and wind—both of which contribute to fire spread. Another misconception perpetuated by the timber industry is the idea that dead trees are somehow undesirable and an indicator of “unhealthy” forests. In reality dead trees are the foundation for forest soil productivity. Dead trees are also important for most forest dwelling species—with fully 2/3 of all forest species dependent upon them at some point in their lives. Wildfires, along with insects, are the major agents for producing dead trees and contributors to healthy forests. Contrary to popular opinion, our managed forests are the ones that are “unhealthy” and “sick”. Managed forests typically have less dead trees, and are biologically impoverished and degraded.

–Author Bio: George Wuerthner is a former BLM biologist who has taken 28 ecology and more than 60 science courses. He has taught ecology and environmental studies courses for UC Santa Cruz, UC Santa Barbara, San Francisco State University, Prescott College, and the U of Vermont. He is the author of Wildfire: A Century of Failed Forest Policy and 33 other books related to natural resources, geography and conservation history. wuerthner@earthlink.net