Examining Historical and Current Mixed-Severity Fire Regimes in Ponderosa Pine and Mixed-Conifer Forests of Western North America

The other day I got the following note and link to some new relevant research from Douglas Bevington, author of The Rebirth of Environmentalism: Grassroots Activism and the New Conservation Movement, 1989-2004.  Bevington’s note is shared below with his permission, along with a link to the new study and article. . – mk

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I wanted to let you know about an important new study that was just published by the high-profile science journal PLOS ONE. The article, titled “Examining Historical and Current Mixed-Severity Fire Regimes in Ponderosa Pine and Mixed-Conifer Forests of Western North America,” was co-authored by 11 scientists from various regions of the western US and Canada.

Their study found that there is extensive evidence from multiple data sources that big, intense forest fires were a natural part of ponderosa pine and mixed-conifer ecosystems prior to modern fire suppression. These findings refute the claims frequently made by logging and biomass advocates that modern mixed-severity forest fires (erroneously called “catastrophic” fires) are an unnatural aberration that should be prevented through more logging (“thinning”) and that more biomass facilities should be built to take the resulting material from the forest.

In contrast to these claims, logging done ostensibly to reduce fire severity now appears to be not only unnecessary, but also potentially detrimental when it is based on erroneous notions about historic forest conditions and fire regimes. These findings have big implications for biomass and forest policy, so I encourage you to take a look at this article.

The full article in PLOS ONE is available here.

Here are a few key points from the abstract and conclusion:

Abstract, p. 1

“There is widespread concern that fire exclusion has led to an unprecedented threat of uncharacteristically severe fires in ponderosa pine and mixed-conifer forests of western North America. These extensive montane forests are considered to be adapted to a low/moderate-severity fire regime that maintained stands of relatively old trees. However, there is increasing recognition from landscape-scale assessments that, prior to any significant effects of fire exclusion, fires and forest structure were more variable in these forests….We compiled landscape-scale evidence of historical fire severity patterns in the ponderosa pine and mixed-conifer forests from published literature sources and stand ages available from the Forest Inventory and Analysis program in the USA. The consensus from this evidence is that the traditional reference conditions of low-severity fire regimes are inaccurate for most forests of western North America….Our findings suggest that ecological management goals that incorporate successional diversity created by fire may support characteristic biodiversity, whereas current attempts to ‘‘restore’’ forests to open, low-severity fire conditions may not align with historical reference conditions in most ponderosa pine and mixed-conifer forests of western North America.”

Conclusion: p. 12

“Our findings suggest a need to recognize mixed-severity fire regimes as the predominant fire regime for most of the ponderosa pine and mixed-conifer forests of western North America….For management, perhaps the most profound implication of this study is that the need for forest ‘‘restoration’’ designed to reduce variation in fire behavior may be much less extensive than implied by many current forest management plans or promoted by recent legislation. Incorporating mixed-severity fire into management goals, and adapting human communities to fire by focusing fire risk reduction activities adjacent to homes, may help maintain characteristic biodiversity, expand opportunities to manage fire for ecological benefits, reduce management costs, and protect human communities.”