The Dixie Fire: Is a landscape level fire-resistant forest possible?

 

By Mike Yost

Member Quincy Library Group

 

The Dixie Fire has been the most severe and the most resistant to control of any fire we have experienced here. It has impacted ecosystems and lifestyles we will have to live with for a long time.

This mega-fire has highlighted the importance for homeowners to develop defensible space around structures as well as hardening homes against wildfire embers.

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However, the most important lesson to be learned from the Dixie Fire is that current fire-fighting strategies are not sufficient to control today’s wildland fires with the dense fuel and the hot, dry weather conditions that accompany climate change.

Climate change is beyond the control of local forest managers, but landscape-level strategies for managing fires can and must be developed.

One strategy that shows promise was implemented in the early 1990’s by the Quincy Library Group. These were shaded fuel breaks, also known as “Defensible Fuel Profile Zones” or “DFPZs.”  The Quincy Library Group developed the “Community Stability Proposal” in 1993 and lobbied Congress to pass the Forest Recovery Act in October 1998. A  major component of the Act was to direct the U.S.Forest Service to construct a strategic network of DFPZ’s on the Plumas, Lassen, and Sierra Ranger District of the Tahoe National Forests. It was suggested that DFPZ’s be constructed around communities, along ridge-tops and roads throughout the QLG Pilot Project Area. 

It was also suggested that the network of DFPZs be inter-connected. Over the next decade, many DFPZ’s were constructed. However, few of them were designed to protect communities and most were not connected in a network.

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Shaded Fuel Breaks, including DFPZs, are usually 1/4 mile wide and as long as topography dictates. Most understory fuel is removed and the overstay is thinned so that crowns are not touching. This creates a forest stand that is very similar to pre-settlement forests.

During the 1990’s fire fighters reported of use of previously constructed DFPZs successfully suppressed wildland fires that interacted with them. In 2010 the Plumas Forest Fuels Officer, the Plumas Forest Ecologist, and the Regional Fuels Officer reviewed all the fires that had interacted with DFPZs within the Quincy Library Group Pilot Project Area from 1999 to 2010. The results of their study were published in a USDA Report in 2010 entitled:  A Summary of Fuel Treatment Effectiveness in the Herger-Feinstein Quincy Library Group Pilot Project Area by Kathy Murphy, Pete Duncan and Colin Dillingham (This report is available online)

A brief summary of their findings includes the following:

Summary of Key Findings

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° “Fuel treatments were effective in modifying fire behavior, resulting in a reduction in final fire size and reduced suppression costs.”

° “Thinning and prescribed fire, used in combination, modified wildfire behavior more effectively than thinning alone and with less tree mortality than lop and scatter and mastication treatments.”

° “Treated areas had the least vegetation mortality and resulted in retaining a forest after wildfire, maintaining ecological and social benefits of a forest such a wildlife habitat, recreational enjoyment, and numerous other benefits.”

° “Untreated areas experienced the most severe fire effects and vegetative mortality.”

° “Treated areas increased fire suppression options and enhanced opportunities for safe, low-severity burnout operations with reduced potential for spotting and torching.”

° “Smoke volume was reduced significantly when fire reached treated areas.”

The Report concludes that of the 20 wildfires that interacted with DFPZs from 1999 to 2010, 19 were successfully contained within the fuel break areas. One fire spotted over the DFPZ.

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DFPZs are not expected to be a final solution. They are the first stage of a comprehensive strategy — a place to start. Eventually, large portions of the landscape would be treated similarly. The strategic placement of DFPZs is designed to create a network in which the average area of fuelbreak-surrounded forest would be no larger than a few thousand acres. Firefighting efforts would be directed toward containment of fires within these areas.

The ultimate goal would be to thin most of the forest landscape.

The results of this experiment should be enough to encourage the U.S.Forest Service to continue constructing DFPZs across the forest landscapes. With no other reliable strategy known, now may be the time to develop a DFPZ network throughout Sierran forests.

Fire has been an integral component of Sierra Nevada mixed conifer forests for millenia. Prior to Euro-American settlement, frequent fires played a significant role by reducing accumulated surface fuels and maintaining open under-stories relatively free of fuel ladders that carry fire into the forest canopy. Fire was also a major factor in maintaining the ecological balance of tree species in these forests. Frequent fires reduced the density of shade-tolerant, fire-sensitive species and favored the more fire-resistant species.

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These fires were mostly started by lightning and by native Americans burning to clear the under-story around their settlements. Locally, the Maidu people, like native Americans throughout California, used fire extensively to facilitate hunting and food resource management.

All that changed about 150 years ago.  By the middle to late 1800’s Native American burning was halted by the destruction of their cultures when non-native settlement occurred throughout the Western U.S.  Then in 1910, the newly created U.S.Forest Service adopted a policy of suppression of all fires on national forests as quickly as possible. This policy was a response to an extremely large fire on national forests in Idaho and Montana (the “Big Burn”) which destroyed 3 million acres in 36 hours, killed 97 people on 10 national forests, and destroyed whole towns.

That fire suppression policy continues to this day.

Ponderosa Pine was once the dominant species here. These old trees, growing in open stands, were very large in diameter and had thick bark and deep tap roots which increased their resistance to damage from ground fires. Harvesting these trees and suppressing the light ground fires over the past 110 years has resulted in a much denser forest of under-under-story White Fir, Douglas Fir, and Incense Cedar. These species thrive when there are no fires and they typically have foliage extending to the ground because they have adapted to growing in shaded conditions, Now, when fires do occur, these trees become torches and in dry, windy conditions allow fire to spread vertically up into the crowns of older and taller trees.

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The exclusion of widespread, low severity natural fire, combined with logging of large, fire resistant old growth trees, has resulted in mixed conifers stands with dense under-stories and fire ladders of shade-tolerant, fire-sensitive conifers. Under these conditions, fires tend to be larger, more severe, and increasingly more difficult and dangerous to control.

A network of DFPZs, followed by major thinning and prescribed fire will take decades, but may be the only way to achieve a fire resistant forest.