As wildfire behavior changes, our understanding of what fuel treatments can and can't do is also evolving. A fire ecologist shares his takeaways from the Carr Fire. Credit: Eamon Engber, Whiskeytown National Recreation Area

Fuels Treatments Aren’t a Guarantee, but They Still Matter: Gaining Perspective from the Carr Fire

By: Eamon Engber, Klamath Network Parks and Six Rivers National Forest

Topic: Fuels treatment / Prescribed fire Wildfire

Type: Success Story / Lessons Learned

I’m not sure our messaging surrounding fuel management is clear, consistent or rooted in the best available science and current fire regimes.

During the first two days that the 2018 Carr Fire blew up, the fire burned into the wildland-urban interface (WUI) community of West Redding. Based on the life, property and infrastructure at risk, firefighting resources were rightfully more focused on the WUI rather than the backcountry. During this same time frame, the fire burned through much of those less developed areas, including in and around Whiskeytown National Recreation Area (NRA). And, it burned from the (human) ignition point at the bottom of the slope, up to a ridgetop, gaining momentum along the way. Had it been a smaller fire, during a less extreme fire-danger day, located further from a community, or a lightning ignition on a ridge top, perhaps more of Whiskeytown’s previous fuels treatments could have helped confine the fire. But that’s not how it played out, and I worry that without better messaging around fuel treatments, people won’t understand why.

In total, the Carr Fire led to eight fatalities, and it burned 229,651 acres, and 1,614 structures. It burned through a majority of Whiskeytown NRA in three days, mostly at moderate (about 25 percent of the area) and high (about 55 percent of the area) severity; see the severity map for more details. It had significant negative impacts to park infrastructure, employee housing and natural and cultural resources. It made it onto CAL FIRE’s list as the eighth most destructive wildfire in California — ever (PDF, 148KB). Given that it burned through multiple fuels treatment projects that were implemented over the past 1–3 decades (a scenario that is normally one of the more exciting and fulfilling parts of the job), the fire made me pause and contemplate the role of fuels treatments under modern fire regimes. Which begs the question, is the Carr Fire an anomaly, or a window into the future of wildland fire in California? I’m an optimist but I’m also not naive, and the trends are not looking good (two other California fires in 2018 made the same “Top 20” list). So, where does that leave those of us working so diligently in fuels management?

Map showing burn severity within Whiskeytown National Recreation Area

This map depicts the Carr Fire’s burn severity within the Whiskeytown National Recreation Area boundary. The table at the bottom lists the percent area burned by severity class. Shaded areas with dates represent previous controlled burns. Credit: Eamon Engber, Whiskeytown National Recreation Area

To be clear, most fuels treatments are not designed to 1) function well under extreme burning conditions, or 2) stop a wildfire without additional intervention. However, they are designed to 1) reduce fire intensity, rate of spread and post-fire severity, thereby protecting key values at risk, and 2) provide operational opportunities for fire managers to more safely and successfully fight fire. We need to do a better job disseminating the purposes and parameters of fuels treatments if we want to maintain support for fuels management. And we need to be smarter about where and how we prioritize implementation.

Once the smoke settled, I examined several questions. First, were any of the Whiskeytown treatments effective in reducing fire intensity and severity? Was there greater tree survival within fuels treatments compared to adjacent areas? The answers are mixed, but there were some success stories and lessons learned I will share here:

  1. Many recent (as in less than 5-years-old, but mostly 1-3-years-old) prescribed fire projects slowed fire spread and reduced fire severity (again, see the fire severity map). Still, many recent burns were overpowered by topography, weather and plume-dominated fire behavior.
  2. Areas with two or more prescribed burns within the last 10 years seemed to fare better, with more tree survival, relative to untreated areas, although even some of these treatments burned hot. Modern fire regimes may require more frequent treatment intervals (which could have unintended consequences on vegetation).
  3. Areas that were thinned (from 400+ trees per acre down to 100–200 trees per acre) reduced the incidence of crown fire, but adjacent untreated stands still facilitated high levels of crown scorch within treated areas (i.e., edge effects occurred).
  4. Areas that were thinned and then received prescribed fire (see Brandy Creek project photos at the top of the post and below, a forest thinning project followed by a controlled burn completed the year prior to the Carr Fire), showed minimal overstory mortality, except on treatment perimeters. This supports the notion that thinning should be followed up with prescribed fire, whenever possible.
  5. Defensible space is critical. Many more buildings in Whiskeytown NRA may have been lost if not for the defensible space projects that facilitated the safe and effective engagement of fire resources.
Aerial view of a portion of the Carr Fire burn area, with recent fuels treatments also delineated. The units burned in 2017 appear less damaged by the Carr Fire than those treated in 2013.

Aerial post-Carr Fire imagery, displaying forest thinning units that were also treated with prescribed fire one year prior to the Carr Fire. Credit: Eamon Engber, Whiskeytown National Recreation Area

Forested area with scorch on understory shrubs but retention of overstory trees

Brandy Creek thin-and-controlled-burn project area, displaying scorch on understory shrubs but retention of overstory trees following the Carr Fire. Credit: Eamon Engber, Whiskeytown National Recreation Area

Moving forward, my team is looking at all the options to make Whiskeytown NRA more fire resilient in the future: following up with controlled burns in areas that fared well during the Carr Fire (to maintain low fuel loads), emphasizing the fundamentals of defensible space around structures and infrastructure, and trying to better understand the conditions under which fuels treatments become ineffective in volatile vegetation types. As fire regimes increase in intensity, scale and frequency, I believe fuels management continues to be an important component of fire management, but we need to understand and acknowledge that treatments may bear shorter lifespans, require different intervals or techniques, and in the most extreme cases, be ineffective. Treatments create opportunities for intervention during wildfires, but complex wildland fire environments may sometimes compromise the ability for treatments to be utilized. This needs to be acknowledged.

That said, I’m still optimistic about the value of this work ⁠— it can be effective, and the small success stories from the Carr Fire speak to this. But, we need to collectively refine our messaging surrounding fuels management, and we need to be diligent about choosing those places where we are most likely to have success, acknowledging that the fire environment is changing. Then we need to get out and do the work, with a sense of urgency commensurate with the values at risk.

Eamon Engber is an interagency fire ecologist with the National Park Service — Klamath Network Parks — and the Six Rivers National Forest.

Eamon’s “Carr Fire Story/Effects of Rx Fire on Wildfire” presentation, which he delivered at the 2019 Northern California Prescribed Fire Council spring meeting, can be viewed online.

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8 thoughts on “Fuels Treatments Aren’t a Guarantee, but They Still Matter: Gaining Perspective from the Carr Fire”

  1. Denise Enea says:

    Thank you for your article. Seems that creating a healthier forest by thinning likely is also a benefit for reducing tree mortality especially in drought years. Increased tree mortality we know will have a large effect of intensity and rate of spread. Pretreatments therefore could have a measurable impact in areas near the WUI in keeping the forest healthier than in just left untreated.

  2. Thank you. This is very helpful for our Fire Safe Council

  3. D. WOODHAM says:

    YES to this article for so many reasons! Explaining to landowners unfamiliar with wildfire that we can’t change the weather, we can’t change topography but we CAN change the fuels is what make sense them. Then following that up with an explanation of how fuels manipulation can help to alter potential fire spread and behavior, as well as potentially provide safer management opportunities to fire crews, MAKES SENSE. People GET THAT! But the conversation HAS to have both components- the steps to alter potential & the basic fire operations. People envision fire management to be some mysterious enigma, but are always surprised to learn it’s actually common sense.

  4. Eamon Engber says:

    Thanks for the positive comments. We’re facing some big challenges in fire management right now but they are not insurmountable and doing nothing is not a good option. That said we need to be thinking critically about the best use of limited funds and prioritizing treatments where they will have the most benefit. And we all have a stake in this – from small landowners up to the agencies. Keep up the good work!

  5. D. B. Carlson says:

    Very thoughtful and useful. Thanks. It would also be helpful to have examples of the effects of fire in different types of woodland. Most examples seem to consist primarily of areas populated with conifers. What differences occur in CA oak woodlands or woodland/grassland situations, if there’s any experience? Is the incidence of crown fire different, and if so, how? Is the flammability of understory in oak woodlands comparable to, or different from that of conifer forest?

  6. I like the terminology when talking about changing the fuel levels, ie “altering potential” for fires to burn intensely. We in Australia use terms like “mitigation” but lowering the potential for intense fires and thus allowing fire operations to occur makes more sense.

  7. Lyn Javier says:

    Thank you for the article Eamon, great information for our FSC & Fire & CERT.
    Thanks to all you who shared too.

  8. Gary Marshall says:

    Thank you for this article, it explains vegetation fuel and treatments that will reduce fire intensity which can aid firefighters. It also assists forest health in many ecosystems. We need to add that structures are fuel and often will ignite as easily as vegetation and will burn much longer producing excessive heat with larger fire brands. The greatest amount of structures that burn are ignited from airborne embers landing either on or at the base of the structure. The flammability of the structure and its immediate surroundings (including other structures) will determine if a structure will survive, leading me to ask the question, are we targeting the right fuel. I believe in the vegetation fuel treatments but there is so much more the public can be doing to prevent structure ignition. Better land-use laws, lower density housing and using exterior fire resistant building materials and practices in addition the use of fire resistive plants and maintenance of other man made fuels around the structure. Most building codes are based on a firefighter response. Firefighters do a wonderful job. We also know that 2-3% of all fires, there may not be the resources for suppression activities, therefore the structure is on its own.

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