The QLG Fuelbreak Strategy

Paper adopted at the QLG meeting of 1/30/97

Several Forest Service projects in Region 5 have been questioned, criticized, or appealed on grounds that they propose to create Defensible Fuel Profile Zones (DFPZs), or their equivalent by some other name, which are not properly authorized or supported by Land and Resource Management Plans (LRMPs) or other governing documents and processes. QLG is sometimes credited (or blamed) for its part in developing the DFPZ concept; therefore we wish to explain the concept we actually do promote, and contrast it with some other ideas we do not support.

What the QLG Strategy IS:

Since 1994 QLG has pushed for "a network of defensible fuelbreaks" as the first stage of a comprehensive strategy to improve our protection from large-scale high-intensity wildfire. These fuelbreaks would not be instead of general area thinning, but rather the conduct of early thinning efforts in a strategic pattern. The idea is to gain immediate leverage by breaking the continuity of fuel beds and fire ladders, so that longer term, wider area fuel reduction, and other efforts at better vegetation management, would have some chance of being successful before the associated economic, wildlife, soil, and watershed resources are badly damaged or destroyed by high intensity fire.

Specifically, the first stage of the QLG strategy places the highest priority on treating 1/32 of the forested acreage each year, for at least four years, such treatment to be in strips of about 1/4 mile width, located where possible along existing roads. These strips should form a network (not a square "grid," but an irregularly shaped network) that generally reflects the pattern of existing roads and the locations of particularly hazardous fuel concentrations and assets of high value that most need immediate protection. In four years this schedule of treatment (approximately 50,000 acres per year in the QLG Area) would create a network in which the average area of fuelbreak-surrounded forest would be no larger than 10,000 to 15,000 acres.

Each quarter mile wide strip should be "thinned from below" to de-fuse the fire ladders that are essential for the initiation and propagation of crown fires and other characteristic phenomena of high-intensity wildfire. Each strip should include a firefighter safety area along the road, to provide rapid access or retreat and a safe efficient base for suppression activities.

The resulting crown cover in these strips should be thin enough to prevent crown fire propagation when not continuously fed by understory fuel, yet thick enough to retard the rapid growth of new vegetation. (It appears that 30 to 40 percent crown cover would be an appropriate balance in most forest types, but the exact balance needs to be determined for each situation, and the initial estimates need to be improved with experience.)

After the initial period of about four years, additional treatment should proceed at the same pace over the rest of the QLG "on base" area, probably creating some additional strips that further sub-divide the network, but also beginning area treatments of high priority. These area treatments would also aim to reduce fuel beds and fire ladders, but probably to a standard somewhat less strict than the defensible fuelbreak prescription, and without the need to support direct suppression of intense wildfire within these areas.

An independent assessment of the QLG defensible fuelbreak strategy appears in Volume II, Chapter 56, of the Sierra Nevada Ecosystem Project (SNEP) Final Report to Congress. Excerpts from that assessment are attached to this paper as Appendix A.

QLG also recognizes that epidemic insect infestations are a major forest health concern. Implementing the QLG strategy would not only reduce the hazard of high intensity fire, it could also greatly reduce insect problems, because one of the best and safest ways to control insects is to thin over-crowded stands by the same "thin from below" techniques that are proposed by QLG for fire protection.

What the QLG Strategy IS NOT:

These are NOT "firebreaks" skinned to bare ground. Instead, the intention of thinning the fuel beds and fire ladders is to prevent a fire from "crowning," or to bring a crown fire to ground and reduce its intensity to a level where suppression efforts will actually have a chance to be effective.

This is NOT an attempt to do away with other fire prevention and fire suppression efforts. Instead, the intention is to multiply the efficiency of fire suppression and to limit the probable size of an intense fire to a fraction of some actual fire sizes experienced in recent years. A major hazard of recent fires has been their tendency to become "complexes" of several fires from separate simultaneous ignitions (usually by lightning) that can overwhelm suppression resources and spread largely unchecked until the weather changes. With rapid access to good defense lines (and the assurance of safe retreat if needed), suppression forces will be made more efficient and less likely to be overwhelmed by simultaneous ignitions. With strips of thinned canopies and reduced understory density, an air drop of fire retardant can be more effective and/or spread over a greater area, because more of the retardant can penetrate to the understory fuel where it is most effective. Suppression will still be needed; the "leverage" attained with this strategy is to multiply the efficiency of suppression.

This is NOT a proposal "against" the use of prescribed fire. In our forests, with their current fuel loads, mechanical removal of large amounts of fuel, largely in small green trees, is a pre- condition for the desired increase in the use of both natural and management-ignited prescribed fire. For many reasons, large areas of low intensity fire are probably essential for the long term health of much of our forested land. Several barriers now prevent that scale of prescribed fire, but the most decisive barrier is the understory fuel load. It's easy enough to burn large areas, but in current conditions it would be impossible to control the intensity of large area prescribed fire. After a network of basic protection is in place, and when large areas have had their fuel ladders removed or greatly reduced, then large scale use of prescribed fire may be feasible. Until then, it is not a case of our being for or against prescribed fire; an adequate scale of prescribed fire is simply not a feasible solution to the immediate problem.

The QLG strategy is NOT a substitute for other forest health measures. We believe our efforts to gain some quick leverage on the hazard of intense wildfire is a pre-condition to any successful attack on the numerous other forest health and community stability problems that face us. We ask to have a very high priority for this strategy, but not to have it completely over-ride all other considerations.

The QLG Strategy Compared to Some of the Proposed DFPZs.

In 1995 the Lassen NF, the Plumas NF, and the Sierraville Ranger District of the Tahoe NF ("The QLG Area") published the Technical Fuels Report (TFR), which describes a fuel reduction strategy based on DFPZs (Defensible Fuel Profile Zones), CDZs (Community Defense Zones), and FRZs (Fuel Reduction Zones). QLG participated in this effort by requesting special funding for it, and by providing the Forest Service with explanations of the QLG defensible fuelbreak strategy, but otherwise the TFR is entirely a Forest Service document.

For the most part, QLG supports the TFR as far as it goes. Unfortunately, the concepts described in the TFR have not been subjected to the inter-disciplinary process of analysis, critique, prioritization, and further development, or to public participation in these processes, that is said to be normal Forest Service procedure. Lacking that internal development, and not having public participation, the TFR cannot legitimately be cited as authority for the implementation of this strategic concept through on-the-ground projects.

QLG has repeatedly asked the National Forests in the QLG Area to complete a long-promised follow-up of the TFR, which would subject it to inter-disciplinary and public processes, in order to build a foundation for eventual incorporation of an adequate fuel reduction strategy into the Forest LRMPs. Major deficiencies that need to be addressed in the follow-up process include:

(1) The TFR does not deal with wildlife or riparian concerns;

(2) It does not propose or validate prescriptions or guidelines for the design of fuelbreak projects;

(3) It does not establish criteria for decisions on which kinds of fuelbreak should have priority over others, or how fuelbreak priorities should be balanced against other considerations.

Until these questions, among others, are adequately addressed at landscape scale, fuelbreak implementation, no matter how well conceived and planned at the project level, will be overly vulnerable to professional and legal challenge.

In voicing these concerns, QLG is not opposing implementation of the strategic concept described in the TFR, or opposing any particular project that is directly based on that description.

QLG does oppose having the TFR and its DFPZ concept cited as authority for any projects that include inadequate or badly designed DFPZs, or for other kinds of projects that masquerade as DFPZs.

We are encouraged by recent acknowledgment in SNEP reports and in two drafts of the Cal Owl EIS that strategic fuel reduction is a necessary pre-condition for long term forest health. We continue our strong support for a strategy based initially on a network of defensible fuelbreaks, and we hope that our frank expression of concern over deficiencies and gaps in Forest-level planning for implementation of that strategy will help put it back on track.

Appendix A.

Excerpts from Sierra Nevada Ecosystem Project (SNEP) Final Report to Congress, Chapter 56

Landscape-Level Strategies for Forest Fuel Management

C. Phillip Weatherspoon and Carl N. Skinner,
Pacific Southwest Research Station, U.S. Forest Service.

(The text quoted is in sequence but not in its entirety. Skips are not necessarily marked.)

[In the Sierra Nevada] As a result of largely human activities during the past 150 years, including but not limited to fire suppression, fires now occur less frequently and cover much less area but are much more likely to be large and severe when they do occur. In aggregate, such high-severity fires are well outside the natural range of variability for these ecosystems and are considered by many to be the greatest single threat to the integrity and sustainability of Sierra Nevada forests.

[In the period from 1650 to 1850] A much greater percentage of biomass historically was stored in the boles of large trees and in herbaceous vegetation in relatively open stands, whereas now much more goes into small trees in dense stands.

In pre-settlement forests most biomass ultimately was oxidized by frequent low- to moderate-intensity fires. High-intensity fires more than a few acres in size were unusual. Across much of the landscape, dead biomass on the forest floor was kept at low levels, and most small understory trees were killed and subsequently consumed by fire. While small areas of high-severity fire killed patches of large trees, most large trees survived the fires and were consumed at some point after their death by subsequent fires. Physical removal from the site was a minor component of total biomass disposition...

If we skip now to the twentieth century, the relative roles of fire and biomass removal have changed drastically. As fire suppression was initiated and took effect early in the century, the proportion of biomass consumed by fire dropped precipitously, as did annual burned area. Large fires have composed an increasing proportion of that burned area as the century has progressed. In recent years, large fires have become less controllable and more severe, evidently reflecting in part increased fuel loadings.

As managers began to see the consequences of increased fuel loads, they undertook a variety of fuel-management activities. For the Sierra Nevada as a whole, however, vegetation management activities have produced considerably more new fuels than they have eliminated. Furthermore, the increasing problem of live understory fuels has been addressed inadequately in silvicultural or fuel-management activities. Efforts to treat accumulating amounts of natural fuels, often with prescribed fire, also have fallen far behind rates of fuel accretion, due in large part to inadequate funding and various concerns about the use of prescribed fire. Even the active prescribed burning programs in Sierran national parks over the past twenty-five years, utilizing both natural and management ignitions, have restored fire to the forests at rates well below pre-settlement levels. Consequently, these burns have been unable even to keep up with new biomass accumulation, let alone to consume all the excess biomass generated by decades of fire suppression. The basic problem is the same outside the parks: current quantities of flammable biomass--primarily small trees and surface fuels--in low- to middle-elevation Sierran forests are unprecedented during the past several thousand years and are continuing to accumulate at a much faster rate than they are being removed.

Given current federal and state budget climates, increasing suppression costs, and attrition of skilled firefighters, reductions in suppression forces seem more likely than substantial increases. According to a growing consensus among fire managers, more suppression capability is not the answer anyway.

If more suppression is not the answer, and if flammable biomass continues to accumulate at current rates, and if we do nothing substantial to arrest that accumulation, simple physics and common sense dictate that the area burned by high-severity fire will escalate accordingly. This conclusion is strengthened by the fact that recent "drought" years, during which many large severe fires burned, appear to be relatively common when viewed on a time scale of centuries.

Therein lies the rationale for large-scale fuel management. Given the massive scope of the problem and budget constraints, brute force is likely to be neither feasible nor adequate. A carefully considered strategy is required. Treatments need to begin in the most logical, efficient, cost-effective places. Specific components of biomass--mostly small trees and surface fuels--need to be targeted. We must devise ways to pay for the needed treatments. In general, conditions need to be moved away from dense, small-tree-dominated forests toward more open, large-tree-dominated forests. And the rate of treatment needs to be carefully planned: in the short term, rates of biomass removal may well need to exceed rates of production in order to return these forests to a more sustainable, fire-resilient condition.


The most detailed fuel-management strategies to date have been proposed for the northern end of the Sierra Nevada--the Lassen and Plumas National Forests and the Sierraville Ranger District of the Tahoe National Forest. The two strategies, which were developed semi-independently by the QLG and the U.S. Forest Service, have much in common and build on many of the ideas cited earlier. Rapid implementation of a network of broad fuelbreaks is key to both proposals.

QLG proposes that an intensive four-year effort be focused on installing a network of strips approximately 0.25 mi. in width, mostly along existing roads, that break up fuel continuity across the landscape and provide defensible zones for suppression forces. During this period, essentially all forest management activities, including biomass and other thinnings, salvage activities, and treatment of surface fuels, would be focused on implementing this fuelbreak network. Each year 1/32 of the total forest acreage would be treated, so that at the end of the four-year period 1/8 of the forest would be part of these strips. The strips would have reductions in stand density, lower canopy ladder fuels, and surface fuels, and they would have relatively low levels of snags and large downed woody debris. After the initial period, a longer term fuel-management strategy would add some strips to isolate areas of high value and/or high risk, but the emphasis generally would shift to area-wide treatments.

The Technical Fuels Report is similar in several respects to the QLG proposal. The "defensible fuel profile zone" (DFPZ), a concept first described by Olson (1993), is central to the strategy. Much like a broad fuelbreak, the DFPZ is a low-density, low-fuel zone averaging 0.25 mi in width, located mostly along roads, and designed to support suppression activities. Like the strips in the QLG proposal, DFPZs are intended to be installed over a period of just a few years. [The authors] describe the "community defense zone" (CDZ) as another component of their strategy. A CDZ is designed to reduce the threat of wildfire spreading onto national forest land from private land, or vice versa. Like DFPZs, CDZs would have a high priority for completion within a short period of time. A third type, the "fuel reduction zone" (FRZ), refers to general area fuel treatment that would take place mainly after the high-priority system of DFPZs and CDZs is in place.

[Weatherspoon and Skinner introduce their own "Potential Fuel-Management Strategy for Sierra Nevada Forests," intended to achieve three goals:

(1) Reduce substantially the area and average size burned by large, high-intensity wildfires.

(2) Restore more of the ecosystem functions of frequent low-to moderate-intensity fire.

(3) Improve the health, integrity, and sustainability of Sierra Nevada ecosystems.]

Given the massive scope of the problem that goal 1 is intended to address, a carefully considered strategy is required for prioritizing fuel treatments. We focus our discussion in this section on DFPZ networks. Multiple benefits of DFPZs may include: (1) reducing severity of wildfires within treated areas, (2) providing broad zones within which firefighters can conduct suppression operations more safely and more efficiently, (3) effectively breaking up the continuity of hazardous fuels across a landscape, (4) providing "anchor" lines to facilitate subsequent area-wide fuel treatments, and (5) providing various non-fire benefits. We know of no other strategy with as great a potential in the short term to progress reasonably rapidly toward achieving goal 1. [emphasis added]


A reasonable nominal width for DFPZs is probably 0.25 mi. until experience indicates otherwise. Using the fire-growth model FARSITE to model various fuel-treatment alternatives, van Wagtendonk (1996) found that fires burning under ninety-fifth-percentile weather conditions spotted across 300-ft fuelbreaks under most fuel treatment scenarios but did not spot across 0.25 mi. fuelbreaks under any of the scenarios.




[W]e do not have to have all the answers before beginning needed restoration work. We know enough at this point to recognize that current conditions in most low to middle-elevation forests of the Sierra Nevada are unacceptable in terms of wildfire hazard, diversity, and sustainability. Regardless of the extent to which pre-settlement conditions are used as a guide to desired conditions, most informed people would agree that these forests generally should be less dense, have less fuels, and have more large trees. Even if we have not precisely identified target conditions, we certainly know the direction in which we should begin moving. That beginning alone will require a large measure of commitment and hard work. We can adjust along the way as we learn more and become better able to define desired conditions for Sierran forests.

[end of excerpts from the SNEP report]