Fire and Fuels

Bill Gabbert “took one for the team”- (thank you Bill!)  by reviewing a report requested by Ag and Interior of EPA. As reported by Bill on Wildfire Today, it’s kind of embarrassing that the Departments didn’t take a more active role in design of the project (case studies?) and request involvement of key researchers. It seems to me that both departments (Int and Ag)  have more than the usual amount of experts themselves- both  to focus the questions and pick the right people to get the answers. Perhaps it was a political effort to “get EPA on board” or recognize their air quality authority. If it were me, though, I’d force collaboration on any report between air quality and fire experts in all three departments, and the agencies within each; and clearly define what my questions are. Otherwise to my mind, you are just postponing and possible expanding, Potential  Future Interagency Drama, plus wasting money.

The poorly edited report is not light reading and is a slog to wade through the hundreds of pages.

Many of the report’s “key insights” will not be a surprise to land managers (or anyone with a little common sense and exposure to fire management). Here are samples from Chapter 9, “Integrated Synthesis”:

Smaller wildfires produce fewer public health impacts than larger wildfires.
Convincing the public to evacuate or use air cleaners or HVAC filters to decrease exposure to PM2.5 can decrease public health impacts from smoke.
If a wildfire spreads into an area previously treated with prescribed fire it can reduce additional spread of the wildfire.
Smoke plumes that do not intersect with high population areas or last only a few days are less likely to have substantial health impacts than fires affecting larger populations for longer periods.

What was interesting, though, was the information that Bob Yokelson of the University of Montana contributed to Wildfire Today:

We also stress that, despite the evidence for PM evaporation during aging, there are strong data discussed next, supporting the idea that wildfires produce more PM than spring or fall prescribed fires on a per fuel burned or per area burned basis. Liu et al. (2017) reported that EFs for PM1.0 (gPM1.0/kg fuel burned) are almost four times higher in wildfires (27.1 ± 6.1) than spring and fall prescribed fires (7.3 ± 4.2; May et al., 2014). Our 2 year average ΔPM2.5/ΔCO ratio in aged wildfire smoke (~0.117) is ~1.7 times higher than implied for aged, fall western montane prescribed fire smoke (~0.07) based on May et al. (2014, 2015), suggesting that a remnant of the difference in initial PM emissions can survive aging. Fuel consumption in spring/fall prescribed fires at the national level is typically 7.2 ± 2.7 Mg ha−1 (Yokelson et al., 1999, 2013) as opposed to 34.6 ± 9.9 Mg ha−1 on wildfires (Campbell et al., 2007; Santín et al., 2015).

Combining the emissions and fuel consumption differences implies that wildfires emit 18 ± 14 times more PM per area burned. Although prescribed fires cannot simply replace all wildfires (Schoennagel et al., 2017; Turner et al., 2019), their potential to reduce the level of wildfire impacts deserves more attention. In addition, incorporating higher wildfire initial emissions and temperature‐dependent, post emission OA evaporation may improve models of wildfire smoke impacts (Nergui et al., 2017).”

This OSU study by Johnston et al. is interesting because it suggests that mechanical thinning can be useful in reducing without follow-up prescribed burning, at least for a while, at least in NE Oregon.

Mechanical thinning alone can calm the intensity of future wildfires for many years, and prescribed burns lengthen thinning’s effectiveness, according to Oregon State University research involving a seasonally dry ponderosa pine forest in northeastern Oregon.

Findings of the study, led by OSU research associate James Johnston and published in Forest Ecology and Management, are important because reducing accumulated fuels on federal forestland has been a congressional priority for nearly two decades; research such as this helps determine which techniques work.

Johnston’s team looked at years of data for multiple forest parcels – mechanically thinned stands and unthinned control stands – and used computer modeling to predict the behavior of future fires. The collaboration included his Oregon State College of Forestry colleagues Julia Olszewski, Becky Miller and Micah Schmidt, plus Lisa Ellsworth of the OSU College of Agricultural Sciences and Michael Vernon of Blue Mountains Forest Partners.

“Most of the studies that have been published so far suggest mechanical thinning that isn’t followed by prescribed fire is not as good for moderating fire severity than thinning combined with prescribed fire,” Johnston said. “Some studies have even suggested that thinning without prescribed fire can increase wildfire severity by adding to the buildup of fine fuels on the forest floor.”

Mechanical thinning refers to the use of commercial equipment such as a feller-buncher, which cuts and stacks whole trees, or a cut-to-length harvester and forwarder that results in logs of specific lengths being sent to the mill. In the study areas, all trees up to 53 centimeters in diameter at breast height were removed, and hand crews cut down trees too small for commercial use.

“Our work shows that mechanical thinning can moderate fire behavior even in the absence of prescribed fire,” Johnston said. “That’s good news since prescribed fire on national forests has remained flat over the last 20 years because of shortfalls in U.S. Forest Service capacity, a risk-averse agency culture and regulatory constraints on smoke.”

I guess I always thought “mechanical thinning” was cutting trees and removing them however you wanted, including hand piling and burning.
It’s interesting what Johnston ascribes the difficulties with PB to a “risk-averse agency culture” later he adds a few:

“Less than one-fifth of the area treated with mechanical thinning in the southern Blues has also been treated with prescribed fire,” Johnston said. “Prescribed fire has been significantly slowed by budget constraints, local opposition to fire use, and restrictions imposed by COVID-19 response measures.”

SF Chronicle story..very cool graphics .. also “catching people doing something right”.

Meyers and Christmas Valley area
Up and over the mountains past Echo Summit and back down the ridge, the small communities of Meyers and Christmas Valley near South Lake Tahoe were well prepared for a wildfire — so well prepared that the Caldor Fire skipped over much of it.

A Lake Tahoe Basin fire commission of more than 20 local, state and federal agencies that came together after the 2007 Angora Fire spent years fireproofing the area, which included several fuel treatment projects, which included prescribed burns. The commission produced a meticulous response map showing how firefighters could use those areas to their advantage, Anthony of Cal Fire said.

Large-scale treatment projects like the Caples restoration projects are very effective, Stewart of UC Berkeley said, but difficult to make happen because of the complicated processes and costs. They also often face opposition from area residents and environmentalists over the use of heavy machinery, air quality or change to the landscape, he added.

“We need to do (treatments) on a bigger scale,” he said. “Just look at the scale of these fires. Even with all the resources they threw out, they couldn’t slow these fires down.”

There needs to be a more practical approach to fuel treatments in California, Stewart added. He says agencies need to examine what’s working versus not through data and be willing involve people and ideas that can help projects scale up.

LA Times story:

Susie Kocher, forestry and natural resources advisor at the University of California Cooperative Extension, agreed.

“If you look at any of the fire maps, there’s a big gap between Kirkwood and Tahoe,” said Kocher, who was forced to evacuate her Meyers, Calif., home Monday. “That’s Caples.”

She said that due in part to its allure, the Tahoe area has been more successful than many parts of the Sierra in attracting resources for such projects.

The Tahoe Fire and Fuels Team, a multiagency coalition formed after the damaging Angora fire in 2007, said it has performed 65,000 acres of fuel reduction work in the Tahoe Basin over the past 13 years. The group also helps neighborhoods prepare for fire.

In a recent community briefing, Rocky Oplinger, an incident commander, described how such work can assist firefighters. When the fire spotted above Meyers, it reached a fuels treatment that helped reduce flame lengths from 150 to 15 feet, enabling firefighters to mount a direct attack and protect homes, he said.

“It takes both fuels reduction and active suppression in an environment like this to help the community and the forest survive,” Kocher said.

And an interview in the Sacramento Bee with Scott Stephens, fire researcher..during the fire.

How much consensus is there among fire scientists that these treatments do help?

I’d say at least 99%. I’ll be honest with you, it’s that strong; it’s that strong. There’s at least 99% certainty that treated areas do moderate fire behavior. You will always have the ignition potential, but the fires will be much easier to basically manage.

NEPA nerds Lake Tahoe is the only FS unit with its own CE as far as I know.

Lake Tahoe Basin Hazardous Fuel Reduction Projects. The 2009 Omnibus Appropriations Act (Public Law (Pub. L.) 111-8) established a CE for hazardous fuels reduction projects within the Lake Tahoe Basin Management Unit.

Within the Lake Tahoe Basin Management Unit, projects carried out under this authority are limited to the following size limitations:

a proposal to authorize a hazardous fuel reduction project, not to exceed 5,000 acres, including no more than 1,500 acres of mechanical thinning. (Sec. 423 (a))

This CE can be used if the project:
is consistent with the Lake Tahoe Basin Multi-Jurisdictional Fuel Reduction and Wildfire Prevention Strategy published in December 2007 and any subsequent revision to the strategy;

is not conducted in any wilderness areas; and

does not involve any new permanent roads. (Sec. 423 (a))

A proposal using this CE shall be subject to:

the extraordinary circumstances procedures…; and

an opportunity for public input. (Sec. 423 (b))

Document this category in a decision memo (FSH 1909.15, 33.2 – 33.3). The decision memo should include a description of the efforts taking by the Lake Tahoe Basin Management Unit provide an opportunity for public input.

Cite this authority as Pub. L. 111-8, Sec. 423

Note that this is up to 5,000 acres. I just think it’s interesting and likely related to politics. It’s more important to protect some communities than others?

Thanks to Rebecca Watson for this link to a story in the Wall Street Journal.  Well worth reading in its entirety.

Here’s an excerpt:

The Forest Service’s Moneyball effort began in 2017, spurred by growing alarm within the agency at the emergence of complex “megafires,” blazes of more than 100,000 acres. Forest Service researchers Matthew Thompson and Dave Calkin enrolled in an MIT course on how the data-analytics movement that was revolutionizing professional sports could be applied to other businesses.

The two said it got them thinking: If the Houston Rockets’ then general manager, Daryl Morey—known for using analytics—could use data to conclude that three-point shots were a more efficient way to score than midrange jumpers, could a similar concept be applied to firefighting resources?

 

Fire crews are increasingly relying on data-driven models dubbed “Moneyball for fire” within the U.S. Forest Service because they were developed in part by researchers who studied sports analytics at the Massachusetts Institute of Technology. The models take their name from the Michael Lewis book “Moneyball: The Art of Winning an Unfair Game” about how an Oakland Athletics general manager, Billy Beane, crunched numbers to assemble a winning team on a limited budget, where the intuition of team scouts had previously dominated baseball decisions.
Fire Behavior Analyst Glen Lewis views wildfire-modeling tools at the incident command post forfires including the Divide Complex in Montana last month.

The new wildfire models are more sophisticated than more-rudimentary versions used in the past and help firefighters determine how to most effectively deploy limited resources. “It used to take me four to five hours to draw a fire map,” said Mr. Volmer. “Now I can plugin a program and it will spit out all my data in about five seconds.”….

The programs can then churn out various models to predict what the fire will do in the short, near and long term. Analysts can also use the models to simulate thousands of artificial scenarios during an even longer period to predict where a fire might spread under various conditions.
“The models are looking at the history of these landscapes and saying: These are the places where fires traditionally stopped,” said Mr. Calkin. “These are the conditions and locations where you could stop them; and this is where it is probably really ugly to put your people.”
Mr. Thompson and his team began doing presentations around the country for veteran wildland firef ghters, trying to convince them that the numbers they were crunching could help inform their decisions. The team used maps showing the efficiency of the Houston Rockets’ shot selection to illustrate how to better use air-tanker drops by deploying them in locations with a high probability of controlling a fire.

They stressed that the fire crews still needed to affirm the models with what they were seeing. That information would be fed into the models to help make them more accurate. Where crews once mapped out fires by driving around or flying over the blazes, the Moneyball team could instantly show a fire’s projected path under various scenarios.

Mr. Thompson said his group’s persuasion eff orts reminded him of a scene from the film version of “Moneyball,” when a scout tells the A’s Mr. Beane, played by actor Brad Pitt, that baseball teams aren’t picked with numbers but with the scout’s gut, drawn from decades of experience. “I was in rooms where that exact sentiment was expressed,” he said.

 

And what do “on the ground” folks think?

Among skeptics was Rob Powell, wildfire operations chief for South Dakota. “They brought us this big pretty map with all these colors—it was like ‘Tell us something we don’t know,’ ” he said of his introduction to the models in 2018. “But now I see some of the value—especially when I can see the fire on their models before I get there.”..

Rick Stratton, a Forest Service fire-modeling analyst, said the Moneyball models were used to help fight 11 big fi res in 2017, 19 the next year and more than 90 so far this year.

One of its biggest successes this year came in the 70,000-acre Tamarack Fire, which burned in California and Nevada , started with a lightning strike south of Lake Tahoe on July 4. Mr. Stratton used modeling to show it headed toward several small communities along Highway 395 in western Nevada.
Dan Dallas, the supervisor of the Rio Grande National Forest in Colorado, who also commanded firefighting operations on Tamarack, used the modeling to request a surge in fire crews. An interagency group made up of federal and state agencies dispatched five elite “hotshot” crews to the area, helping keep the fire from destroying more property, Mr. Dallas said.

Note: Zybach wrote this a year ago, following the Labor Day fires in Oregon.

The most deadly, destructive, and widespread catastrophic wildfires in Oregon’s history erupted on Labor Day this year, driven by strong east winds. But unless we change how our national and state forests are managed, these events will be just another chapter in this age of predictable, increasing, and ever-greater firestorms.

I spent my career studying forest fires and forest health. For example, my doctoral dissertation from the OSU College of Forestry was titled, The Great Fires: Indian burning and catastrophic forest fire patterns of the Oregon Coast Range, 1491-1951.

In a 2018 interview, just before the California Camp Fire destroyed the town of Paradise, I said: “You take away logging, grazing and maintenance, and you get firebombs.” Then someone took my quote, pasted it on a forest fire photo, and the resulting meme quickly went viral on Facebook.

This September Facebook began flagging this post as “partly false” because my quote, and related interview, doesn’t mention climate change. Evidently Facebook’s executives feel their new-found forestry judgment is better than my lifetime of scientific research and hands-on forestry experience.

The broad arc of Oregon’s fire history explains why this year’s catastrophic wildfires have converted our public forests into unprecedented firebombs. What were once green trees filled with water, have now become massive stands of pitchy, air-dried firewood.

For thousands of years ancestral Oregon Indian families kept ridgeline and riparian areas open for travel, hunting, fishing, and harvesting purposes. They cleared ground fuels by firewood gathering and seasonal fires. This created systematic firebreaks in a landscape characterized by southern balds, huckleberry fields, camas meadows, oak woodlands, and islands of mostly even-aged conifers.

Following the 1910 firestorms, the US Forest Service established a nationwide system of fire lookouts and pack trails backed up by rapid response fire suppression. This system became remarkably effective over time. From 1952 until 1987, only one forest fire in all of western Oregon was greater than 10,000 acres: the 1966 43,000-acre Oxbow Fire in Lane County.

But since 1987, Oregon has had more than 30 such fires, with several larger than 100,000 acres. The 2020 Labor Day Fires alone covered more than one million acres, destroyed over 4,000 homes, caused 40,000 emergency evacuations, killed millions of wild animals, and blanketed the state with a thick, acrid smoke that obscured the sun for days.

What changed to cause this dramatic increase in catastrophic wildfire frequency and severity?

The problems began in the 1960s, with apparently well-intentioned national efforts to create large untouchable wilderness areas and cleaner air and water on our public lands.

The single biggest turning point in how public forests are managed happened on December 22, 1969: about 50 lawyers in Washington, DC created the Environmental Law Institute, and a short distance away Congress passed the National Environmental Protection Act (NEPA).

Next, the 1973 Endangered Species Act (ESA) and the 1980 Equal Access to Justice Act (EAJA) provided the growing environmental law industry with a way to be paid by the government for challenging nearly every attempt to log or otherwise actively manage public forests.

By the 1980s, the artificial creation of Habitat Conservation Plans (“HCPs”) and the listing of spotted owls as an Endangered Species laid the groundwork for today’s fires.

The 1994 Clinton Plan for Northwest Forests might have been the final nail in the coffin. The subsequent never-ending environmental lawsuits, new Wilderness and HCP creations, access road decommissionings, and fruitless public planning exercises have created tens of millions of acres of massive fuel build-ups and “let it burn” policies that have decimated our forests.

The predicted result has been ever larger western Oregon forest fires. More than 90% of these large- and catastrophic-scale fires have taken place in federal forestlands, which only represent 50% of Oregon’s forested areas.

Even if — like Facebook executives — you believe these fires were somehow sparked by climate change, you should be very concerned with what will happen next.

Lessons from the 1933-1951 “Six-Year Jinx” Tillamook Fires and the 1987-2018 Kalmiopsis Wilderness Fires are clear: unless removed, the dead trees resulting from these fires will fuel even greater and more severe future fires.

Forests of dead trees are far more flammable, dangerous, and unsightly than those with living trees. Dead trees dry out, and dead forests become firebombs that almost certainly will burn again and again, unless something is done.

The 2020 fire-killed trees should be mapped, sold, and harvested ASAP. Prices for Douglas fir logs are at a record high, and there is a great need for good-paying rural jobs. The initial focus should be on the dead trees east of Portland, Salem, Eugene, Ashland and the rural towns directly affected by this year’s fires.

Salvage logging must be done soon to be economical: dead trees deteriorate rapidly.

The 1962 Columbus Day windstorm downed 9 billion board feet on a Friday, and by the following Monday salvage logging on public lands had already started. But the 2002 Biscuit Fire burned a roughly equivalent amount of timber, and it took years to develop salvage logging plans and deal with court challenges.

All the delays meant salvage logging actually lost the US Forest Service money; very little needed logging was ever completed, and the 2017 Chetco Bar Fire resulted, burned hotter, and spread wider.

This year’s fires killed at least twice as much timber as the 2002 Biscuit Fire, and it greatly damaged and affected urban areas near major cities. So it will be interesting to see if we can learn from Oregon’s fire history and take the prompt, decisive actions needed to avoid the clearly predictable coming firestorms.

Dr. Bob Zybach

This is from the Ten Common Questions paper, a synthesis published in Ecological Application. I’m posting each answer separately. If you use the search box and look for Ten Common Questions, you can find them all.  My introduction to the paper is here. Please put any questions for the authors in the comments; I’ll try to get answers from them. I’d appreciate if the tone were respectful (think graduate seminar, not Twitter).

4. “Should active forest management, including forest thinning, be concentrated in the wildland urban interface (WUI)?”

A question often asked by land managers is where to locate fuel treatments to maximize their advantage while minimizing adverse impacts. The 2000 National Fire Plan (USDA and USDI 2001) and
the 2002 Healthy Forests Initiative identified the need to reduce wildfire risk to people, communities, and natural resources. The 2003 Healthy Forests Restoration Act (HFRA, US Congress 2003) then specified that >50% of fuel reduction funding be spent on projects within the Wildland Urban Interface (WUI), and it reduced environmental review within 2.41 km (1.5 miles) of at-risk communities. The significant increase in homes lost and suppression dollars spent in the WUI in subsequent years (Mell et al. 2010) has catalyzed extensive research on the WUI environment and population expansion into wildlands (Radeloff et al. 2018). Subsequent studies demonstrating fuel treatment effectiveness in the WUI (Safford et al. 2009, Kennedy and Johnson 2014) and spatial methods for optimizing WUI fuel treatments (Bar Massada et al. 2011, Syphard et al. 2012) could be taken to suggest that most fuel reduction should be implemented in the WUI to protect homes and lives.

However, prioritizing the WUI-only for fuel reduction treatments is often too narrow in scope to address broader landscape-scale objectives. For example, Schoennagel et al. (2009) found that more than two-thirds of the area within a 2.5 km radius of at-risk communities was privately owned and unavailable for federally-funded fuel treatments. This finding partly elucidates why most hazard reduction fuel treatments are implemented outside of HFRA-designation. Fuel treatments on federal lands near communities may also be significantly more difficult, expensive, and risky to implement, while air quality regulations and associated risks create disincentives to treating near homes. Alternatively, agencies may be able to meet both annual prescribed burning accomplishment targets and ecological objectives in areas more distant from the WUI with fewer risks, less money, and fewer personnel (Kolden and Brown 2010, Schultz et al. 2019). Further, there is increasing evidence that treating fuels across larger spatial extents in strategically planned wildland locations, rather than immediately adjacent to WUI, can indirectly reduce risk to communities (Smith et al. 2016, Bowman et al. 2020). Benefits of this strategy include increased initial attack and short-term suppression effectiveness, reduced crown fire potential and ember production, reduced smoke impacts to communities, and increased forest resilience (Ager et al. 2010, Stevens et al. 2016).

Fuel reduction treatments can support cultural, ecological, ecosystem service, and management objectives beyond the WUI. For example, treatments that restore the ecological resilience of old growth forests and patches with large and old trees are critical to long term maintenance of wildlife habitats (Hessburg et al. 2020) of seasonally dry forests and terrestrial carbon stocks, and slowing the feedback cycle between fire and climate change (Hurteau and North 2009). Treatments in watersheds that are distant from the WUI and protect municipal and agricultural water supplies are critical to minimizing high-severity fire impacts that can jeopardize clean water delivery (Bladon 2018, Hallema et al. 2018). For example, post-fire erosion and debris flows may cause more detrimental and longer term impacts to watersheds than the wildfires themselves (Jones et al. 2018, Kolden and Henson 2019).

Finally, treated areas outside the WUI can serve as defensible positions for fire suppression personnel that can be used to establish control lines or allow for more flexible suppression strategies,
freeing up resources to protect WUI infrastructure or forests in another area (Thompson et al. 2017), or can support rapid and organized evacuation when they are implemented along evacuation routes (Kolden and Henson 2019). Across complex landscapes, it is more effective in the long-term to prioritize fuel treatments that maximize benefits across large areas and over long time frames, rather than constrain them to the WUI.

*************************

I don’t think any of this is news to TSW readers, though perhaps the citations are and may be very handy to NEPA folks.  We have heard for years the argument that the FS shouldn’t treat fuels “miles from communities”.  And yet yesterday there was a story of a California wildfire traveling up to 8 miles in a single day.  As I’ve said for many years, keeping fires out of town is generally thought to be a good thing.

This is from the Ten Common Questions paper, a synthesis published in Ecological Application. I’m posting each answer separately. If you use the search box and look for Ten Common Questions, you can find them all.  My introduction to the paper is here. Please put any questions for the authors in the comments; I’ll try to get answers from them. I’d appreciate if the tone were respectful (think graduate seminar, not Twitter).

Question 3: “Can forest thinning and prescribed burning solve the problem?”

Fire has been a tool that has been actively used for millennia. Indigenous burning practices maintained prairies, oak and pine savannas, riparian areas, mixed-conifer, hardwood, and dry forests,
and high mountain huckleberry and beargrass assemblages for food, medicine, basketry and other resources (Trauernicht et al. 2015, Roos et al. 2021). Following prolonged fire exclusion, many
seasonally dry forest landscapes that were once frequently burned now are densely stocked with multi-layered canopies that often require thinning prior to restoring fire (North et al. 2012, Ryan et al. 2013). Prescribed burning on its own and in combination with mechanical thinning are essential fuel reduction treatments with demonstrated effectiveness in reducing fire severity, crown and bole scorch, and tree mortality compared to untreated forests (Safford et al. 2012, Kalies and Yocom Kent 2016).  Thinning and burning in partnership with local Indigenous knowledge and practice can support culturally-valued practices, traditions, livelihoods, and food and medicine security (Sowerwine et al. 2019).

Although the use of prescribed burning, often in combination with mechanical thinning, has been shown to be highly effective at mitigating wildfire severity and increasing forest resilience to drought, insects and disease (Hood et al. 2015), these treatments alone cannot address forest management challenges across wNA. Fuel reduction treatments are not appropriate for all conditions or forest types (DellaSala et al. 2004, Reinhardt et al. 2008, Naficy et al. 2016). In some mesic forests, for instance, mechanical treatments may increase the risk of fire by increasing sunlight exposure to the forest floor, drying surface fuels, promoting understory growth, and increasing wind speeds that leave residual trees vulnerable to wind throw (Zald and Dunn 2018, Hanan et al. 2020). Furthermore, prescribed surface fire is difficult to implement in many current mesic forests since fire readily spreads into tree crowns via abundant fuel ladders and can result in crown fires. In other forest types such as subalpine, subboreal, and boreal forests, low crown base heights, thin bark, and heavy duff and litter loads make trees vulnerable to fire at any intensity (Agee 1996, Stevens et al 2020). Fire regimes in these forests, along with lodgepole pine, are dominated by moderate- and high-severity fires, and applications of forest thinning and prescribed underburning are generally inappropriate. However, landscape burning and maintenance of high elevation forests and meadows is part of cultural burning, and high-intensity
crown fire is used operationally on national forests and parks within the US and Canada for landscape restoration objectives (Table 2).

Even where socially and ecologically appropriate, thinning and low-intensity prescribed burning generally require repeated treatments to meet fuel reduction objectives. For example, without prior
thinning, low-intensity prescribed fire, on its own, may not consume enough fuel or cause enough tree mortality to change forest structure and reduce crown fire hazard (e.g., Lydersen et al. 2019b). In contrast, prescribed burns in heavy slash may result in high tree mortality. The first harvest entry into fire-excluded stands often leaves high surface fuel loads and dense understories that require one or more prescribed burning treatments to reduce surface and ladder fuels (Goodwin et al. 2018, Korb et al. 2020). Thus, it often takes multiple treatments and/or fire entries, as well as ongoing maintenance, to realize resilience and adaptation goals (Agee and Skinner 2005, Stevens et al. 2014, Goodwin et al. 2020). Given the extent and variability of forest ecosystems that have experienced prolonged fire exclusion, active forest management can be only one tool to increase adaptation to climate and future fires.

Although thinning and prescribed burning have been shown to be highly effective, the current scale and pace of these treatments do not match the scale of the management challenge (Barnett et al. 2016b, Kolden 2019). Mechanical treatments are constrained by land management allocations and their enabling legislation (e.g., wilderness and roadless areas), operational constraints (e.g., steep slopes, distance to roads, costs), and administrative boundaries (e.g., riparian areas, areas managed for species of concern). In the central Sierra Nevada for example, these constraints – combined with large areas of non-productive timberland that are unsuitable for commercial treatment due to steep slopes or distance from roads – left only 28% of the landscape available for mechanical thinning and prescribed burning treatments (North et al. 2015a). In the remaining area, prescribed burning alone and/or use of managed wildfires may be suitable replacement treatments (Boisramé et al. 2017, Barros et al. 2018). However, prescribed fire-only treatments are frequently limited by cost, liability, air quality regulations, equipment availability, personnel capacity and training, and the need for ongoing maintenance treatments (Quinn-Davidson and Varner 2012, Schultz et al. 2019).

In light of these constraints, some researchers and managers have called for the expanded use of landscape-scale prescribed burns and managed wildfires in addition to fuel reduction treatments as a promising approach to expand the pace and scale of adaptive management (see below). Increasingly collaborative restoration partnerships with Indigenous cultures can increase opportunities for reinstating tribal stewardship practices (Lake et al. 2018, Long and Lake 2018). Under appropriate weather and safety conditions, and where infrastructure is not at risk, managed wildfire may serve as a useful and cost-effective tool for reintroducing wildfire to fire-excluded forests and achieve broadscale management goals.

Sharon’s reflection: In policy studies, we always say that framing the problem is crucial. These scientists ask the question “can thinning and prescribed burning solve “the problem”?” In the abstract, the authors state “We review science-based adaptation strategies for western North American (wNA) forests that include restoring active fire regimes and fostering resilient structure and composition of forested landscapes.”..perhaps how to restore fire regimes and foster climate resilience.  If I were framing the problem I might call it “how can humans in western North America live with fire, including restoring/designing fire resilient forested landscapes.”  It’s not exactly the same thing, but perhaps the answer (thinning and PB can’t do it alone) is the same.