The Science of Forest Fires: Culture, Climate, and Combustion

Published Jul 23, 2018

Professor John Bailey, an expert on all things fire, tells us about controlled burning, silviculture, and why Smokey Bear had it all wrong.

In this episode
  • John talks about topography and wildfires
  • Colleen asks John what silviculture means, and why it's important
  • John explains why he sees an entire forest as fuel
  • Colleen learns what the four housemen of the apocalypse and Smokey Bear got wrong about fire
Timing and cues

Opener (0:00-0:58)
Intro (0:58-2:20)
Interview Part 1 (2:20-13:39)
Break (13:39-13:58)
Interview Part 2 (13:58-25:28)
Sidelining Science Throw (25:28-25:45)
Sidelining Science (25:45-29:20)
Outro (29:20-30:00)

Related content
Full transcript

Welcome to the Got Science Podcast. I’m your host Colleen MacDonald. Here on the east coast, I don’t think a lot about forest fires and massive wildfires. Not the case when I was out on the West Coast recently where drought and wildfire are a constant presence. Today we’re talking to an expert on forest management.

And stick around after the episode for another example of Sidelining Science with Shreya Durvasula.

It’s wildfire season for the American West, and already large and destructive fires have forced evacuations and burned up acres in Colorado, Utah, New Mexico, California, and now Oregon where this week’s guest hails from. Wildfire watchers have warned that this year’s blazes could set records, and the heads of the USDA and the Department of the Interior have already briefed lawmakers to prepare them for a really bad one.

How did we get to this point where wildfire season starts earlier, ends later, and features more intense fires than ever? Is there anything we can do to become more resilient to more frequent and damaging fires? To answer these and other questions on this hot topic, we invited an expert in forest management on today’s show.

John Bailey is a Professor in the Department of Forest Engineering, Resources, and Management at Oregon State University. He’s co-authored the book Silviculture and Ecology of Western US Forests, along with dozens of research publications on forest fires and land management. He joined us to talk about how climate change worsens wildfires, how controlled burns can, counterintuitively, reduce damage from fires, and why Smokey the Bear was wrong about forest fires.

Colleen: So I'm here with Professor John Bailey, out on the West Coast in Corvallis, Oregon. And John, welcome to the Got Science? Podcast.

The first question I want to ask you is what the heck is "silviculture" and have I pronounced it correctly?

Bailey: You've pronounced it very close. Silviculture is just the art and science of growing trees. Like agriculture is for crops, silviculture is for trees. And it's really at the core of forestry since our land management practices, even though we can think on large scales like we will be talking about for a while in fire, we still manipulate the hill sides one tree at a time.

Colleen: Are forest fires different now than they were say, 20 or 40 years ago? It seems with climate change, they're perhaps more intense or more frequent. Give me the lay of the land.

Bailey: Sure. And I think there's pretty widespread consensus that yes, we're seeing more acres burning. The percentage that's burning at high severity is staying about the same, but if you have more acres burning in total, then you have more acres that are burning at high severity, or uncharacteristically relative to historically how we know fires burned through many other western landscapes. But, you know this has application for eastern landscapes as well. The Pine Barrens of New Jersey are fire dependent forests, and the Oak Hickory, kind of, complex in the hardwood forest has a real solid fire history associated with that. The Southeastern Coastal Plain Longleaf Pine Forest is very analogous to the ponderosa pine forest of the West. So this is, not only a western issue, and we can come back to that topic of why these large wildfires haven't been a big issue in the Southeast at least yet.

So there's consensus that we're seeing more acres burning in large fire events that represents some ecological issues, but also, big socio-economic issues as well. And here we can just think about the California fires in Santa Rosa, and the millions to billions spent on suppression activities, but the trillions of dollars that are gonna go to rebuilding and recovery and the amount of damage that was done. And there, we don't even necessarily fully understand how much damage was done. So why has it gotten worse? We can go back to the basics of just fire behavior. Just picture a triangle, and the fire behavior triangle is based on a topography because, you know, slope and the land form that is out there really influences fire, fire spreads up hill. And that's just the physics and chemistry of fire. But we can't do a lot about topography.

Topography is just the playground that fire is out there in that our land management practices are all on. There's climate, so the topography and climate. Climate, day to day weather forms a climatic pattern that drives temperature, relative humidity, and winds. Winds is…or one of the key issues that we have, and it's pretty clear and pretty established now that our fire seasons are longer, hotter, drier, and the, you know, there's always wind out there and so the probabilities are just higher that you get the conditions matched with an ignition that allows for a faster rate of spread. The third side of the triangle is fuels. You know, you have to have the fuels to spread. All other things being equal, fire only follows the fuel, the unburned fuel.

Colleen: So you've described the forest as fuel. Can you explain that? Because I think most people think of fuel as the external thing that you put on something and then light a match or a spark or…

Bailey: If you're thinking about your campfire or your woodstove, then that is fuel that has been transported from, you know, some ecosystem and brought to your controlled environment. So I just remind folks, when you use the word forest or hillside, people just picture different things. It's actually the same thing, and the mental picture, I believe is the same in most people's mind, but in terms of what they really see and feel might be scenery hiking, you know, skiing, other recreational things. Some people see it as clean water, you know, the watershed function that is so important. Eighty, 90% of the clean water in America comes from our forested landscapes. They might see it as wildlife habitat if they're birders or hunters or those kinds of things.

If you're in the timber industry and a private landowner and you have kids you want to put through college, you see that same forest as timber in future money or your investment, the equivalent of your 401(k). People see all these things and, in fact, the forest is all these things. And when I look out there now, given my line of work, I see it as fuel because it is all those things and also fuel, and it's going to burn. And yes, we haven't chopped it down and split it up and feeding it into a woodstove. It burns in place as, you know, any of the 6:00 news programs will show you. It is fuel. And as we look at that combination of topography, climate, and now fuel, there's more of it out there than really we've ever had.

We've created forest types that have never existed before through our land management practices, one of which is fire exclusion. We've kept fire purposefully out of the forest in many areas in the false belief that that was protecting and preserving the forest. So there's more fuel than we've ever had on many, many acres, most acres and therefore those acres are more connected than they've ever been to one another, allowing this fire spread uphill, downwind on very hot days and all that kind of stuff. And that is what's driving the large acreage of uncharacteristic and undesirable fire that we have.

Colleen: Do you feel that you can connect climate change to increase in wildfires?

Bailey: Yes. The actual weather data, year-to-year weather data is pretty clear in terms of the new temperature record. Each year gets warmer. The actual length of the fire season, which is not only the weather conditions, but also deployment of resources in anticipation of…in tracking fuel moisture conditions and all that kind of stuff. The fire season out in the West is 30, 40, 50, 60 days longer than it was 2 and 3 decades ago. So all of that information is clear in addition to the additional acres of high severity fire, in addition to the amount of money and the amount of resources, the percentage of the forest service budget, all of that information for people that want to track that down is available from the National Interagency Fire Center in Boise, Idaho.

Colleen: What are the traditional forest practices that have been in place, and I know you are work on, sustainable forest management practices, but let's start with what's already in place. And then you can tell me about how you would change the management to…

Bailey: Make us more resilient?

Colleen: Yes.

Bailey: To future climate and wildfire, those are typically the words that we use. And I think even before we talk about the history, we can talk about the pre-history, because of some of the lessons that that holds. I mean, you know, you can't go back in time. We now have billions of people on the planet, which is very different from our pre-history, but you know, that established a lot of the ecology and the adaptations that are out there and that we can exercise now to create a more resilient future for us. So, our native American ancestors and ancestors on the other part of the globe, you know, regularly used fire to maintain the forest conditions that they wanted and some of that were their food and game crops and that kind of stuff.

And openness and travel corridors, this is the traditional ecological knowledge that we're assembling and improving every year, medicinal plants. And I think part of it was also so that they would not live in fear of the hot, dry summers that we get every day, at least in the western United States. So, it's very predictable to get the Diablo winds than burned Santa Rosa this past year. I don't think our native American ancestors lived in fear, you know, of those winds knowing that those winds were coming. They just prepared the fuel so that they could manage the impact that it was gonna have on their own communities and their own resources. We haven't done as good a job. So then if we go to the history of Western settlement over the last 100 or 150 years in the West, for a while, we picked up on some of that message of using fire to manage the resources.

But as we expanded our western civilization with roads and railroads and buildings, wooden buildings, we suffered, our ancestors suffered enough losses from fire that the narrative changed to where fire, like wilderness, was a little on the evil side. It was a destructive. So the role of fire as a destroyer started to dominate the narrative, Stephen Pyne has written eloquently on this topic. And that led to the emergence of, a forest service culture amongst others that were really geared around fire suppression. Smokey Bear was part of that message and popular media with Disney and Bambi. Fire is presented as a danger to Bambi, and a destroyer of the fire, and the music is dramatic. There were propaganda posters around World War II that equate fire with Hitler and Mussolini and all of the evil in the world and death, even. You know, the four horsemen riding with fire.

And fire, you know, does have an element of destruction to it, but fire is also a creator. And so I think the prehistory saw the balance between fire as a creator and fire as a destroyer. We lost our understanding of the creative power and the management uses of fire. So with the emergence of the science of fire ecology, understanding that fire history and these ecological adaptations to fire, the role of fire in the natural landscapes and all that really started to solidify 20, 30 years ago, or really in my career. And, you know, I've been part of a much larger effort that builds our understanding of that and starts to translate it. My role has been to try to actively translate that into force management, current, sustainable forest management practices. As we move away from a history of logging where, you know, we were interested in the logs and the economic value that they held. Now, we can balance that also against a more general harvesting practices or maybe we could even call it fuel manipulation because every harvesting practice including logging and getting the big logs out of there, has implications on the fuel.


Colleen: So a follow up question to when you were saying native cultures used fired to prepare. I guess one question is, how do you burn burn certain areas to prepare without having it burn up everything else that you don't want burned?

Bailey: It's an excellent question, and part of it ties to choosing the conditions under which you burn. So I want to come back to that. And part of it is having a fuel limited managed landscape in which, you know, the fire cannot get out of control in a widespread case.

Colleen: So, you could somehow create a barrier or something and then you burn the part that you want and it doesn't?

Bailey: So there are many landscapes have many natural barriers to fire in terms of ridge lines where fire behavior is burning up. Hill hits the top of the ridge, then it has to burn downhill. So it has to…most of the heat and physics is going back into areas where the fuel's already been consumed. So it just uses…it loses a lot of its energy and that positive feedback, and may even go out and may become endothermic rather than exothermic and just go out on its own. So our native ancestors, you know, used that kind of understanding of choosing the conditions under which you burn, so that this year's fire, when it bumps up against last year's fire or the fire three years ago, runs out of fuel and you connect that to the rivers and the lakes and changes in forest vegetation type and how fire spreads differently in grass than it does in shrubs than it does in the forest.

And so I hear stories and read this traditional ecological knowledge where when there's still snow on the ground in certain landscape positions, elevations, north-facing slopes and all that kind of stuff, our native ancestors were burning on dry, south-facing slopes to encourage grass production for game and a handful of medicinal plants that grew in those areas. And then as the fire season developed, even very hot dry conditions, they had already burned the fuel off of these other areas. So those become the fire lines, the holding lines for subsequent fire. And…

Colleen: So it's really the pattern of doing this year after year of, manipulating and moving where you're starting the fire.

Bailey: Think of a jigsaw puzzle in time and space, because the previous burns and the conditions under which fuel regrows, how fast it regrows and what kind of fuel regrows varies how that puzzle piece becomes burnable again, somewhere in the future.

Colleen: So as I'm understanding this story, we've become fearful of fire. So we don't want to burn anything, and then all of our fuels building up and building up and building up and then...

Bailey: The puzzle pieces get thicker, start gluing themselves together into very big flammable pieces. And then when we get an ignition during the really hot, dry conditions, it has a big hunk of the puzzle that it can, that it burns through it once.

Colleen: If I had a magic wand and I said, "Okay, John, we're starting all over and you're gonna run this show here." How would you manage things?

Bailey: So, yeah, we do, we operate and do forestry within the context of social license and that starts with the laws, but then also, our own interpretations of those laws and the training that we give our workforce and the interactions that they have, you know, with the public and all those kinds of things. You know, we haven't been doing as much land management over the last couple of decades as we could have. And that's just backlash from the logging days and the early parts of the environmental movement and the preservation movement. So a first step is to acknowledge that those wars are over, and we've gotta we've got to put that behind us. There is a role of active management of our lands out there. They don't... We don't have to... The preservation model doesn't work in dynamic ecosystems. We know…the science is clear on that.

We've got to see this disruption that we've created in time and space and the fuel bed that we have now and what subsequent wildland fire, what wildland fire so far has been doing to that. And it's pretty easy to see what subsequent wildland fires going to be doing to individual acres, but the larger landscape patterns. So the landscape ecologist are really worried about losing the landscape memory of these patterns of different forest types in different ecosystems on hillsides when wildfire just rolls through everything for that. Step one is just acknowledging that we have that issue, that the preservation model just doesn't work for dynamic ecosystems. It works small spacial scales, and small temporal scales, preservation is a great thing. I use the analogy of pickles, you know. We know that when we try to preserve pickles, you do it in small batches and they're good for a couple of years.

So we now have that acknowledgement and then get moving with active forest management, you know, public and private lands with this new vision that, "Oh yeah, that's right." This is all fuel and wildland fire is going to be an issue because everything that we're doing in our normal course of business for timber, for fiber, for carbon, for recreation, for scenery, for wildlife, habitat for fisheries, all of that kind of stuff. You know, we're motivated, you know, to do a certain amount of land management to meet the needs of our society. We've got to remember that it's also fuels to make sure that all that other stuff we're doing, you know, also has the mindset that, "Oh yeah, these are fuels."

And so what that's going to translate to in reality is getting some of the fuel mechanically off of the landscape, and reintroducing fire in the form of prescribed burning and/or generally opening up the window to actually use wildland fire when we get natural ignitions out there.

Colleen: When you say, "Get rid of it mechanically," what… Does that mean just remove it?

Bailey: Remove it… and, you know, make it into useful products, you know, where we can, and from a carbon perspective in as long lived products as we possibly can.

Colleen: So what would an example be?

Bailey: Houses. Houses for the homeless, right? We have an affordable housing crisis emerging in America, or at least many parts of America. And yet we're sitting on this massive wave of fuel, which is building material.

Colleen: So as you were talking about it before, I was imagining the fuel being trees and all sorts of scrubby, underbrush or whatever, and is that... Is it all part of the fuel?

Bailey: It is all of that and the arrangement, and the physical arrangement of that. So, yeah, so a certain amount of it is not gonna have any building material value, but it might have a biomass value for, you know a small community. Boiler plants for winter heat, summer electricity generation. The Scandinavians have wonderful models for energy independence, get away from fossil fuel consumptions and all.

Colleen: Great. So we remove some of it, we burn some of it. What else can be done?

Bailey: You partner when we get the natural ignitions. So right now we get natural ignitions or careless human ignitions during a full spectrum of fire weather conditions, and in the lowest, you know, end of those, the coolest, most moist, less windy, kind of, conditions, it's really easy to go and put fire out. As a matter…fire…at the far end of that, fire just goes out by itself before we ever even get out there to it. Then we start getting into the part of the spectrum where it's just, kind of, you know, that we fire folks talk about skunky. Fires just, kind of, skunking around out there. And that's doing a lot of ecological good. I think that's a lot of what our ancestors did with this very low intensity, slow rates of spread, very short flame links, flame heights, non-hazardous kind of burning. All in the lower end of that spectrum, but that's when we go and put them out because it's so easy to put them out.

And so when we talk about the fact that we suppress 98%, 97% of fires, those are all ones that we're putting out. The 2% and 3% and maybe it's going to climb to 4% that we can't put out are under the hottest, driest, windiest conditions. And those conditions are getting more frequent, and the probability of them encountering this fuel matrix that we've created has also increased. So you just run the numbers. We're going to have more and more fire. I mean, that is just... It's just inevitable. The…

Colleen: How can you scale up though, when you talk about our ancestors doing this in small scale areas, how do you, you know, at for a state, for the state of Oregon, how do you make that? That's a…that's a big change.

Bailey: Right, and that's where much of the research is these days because on a acre by acre basis, we know how to do these fuels treatments. We know how to connect them to carbon programs, timber programs, wildlife habitat programs, fisheries, stream protection programs. We know all that on a acre by acre basis. The big challenge is ramping up. If, all of a sudden, we handed this climatic and fuel condition to our ancestors 4,000 years ago, they'd be in big trouble because they would not have the resources to address this issue. You know, we at least have all these other interests in our landscape and many more tools and techniques and science to be able to start getting at this issue, doing more of the burning down in this favorable part of the spectrum. Breaking up the fuel beds so that whenever we get the ignitions in their hottest, driest conditions, they don't have as far to go, you know, that's the only solution under those conditions.

We're not going to have enough people. We're not gonna have enough money. We're not going to have enough airplanes. We're just not going to be able to do anything about those conditions other than wait for the weather to change, or have treated areas that it burns into that can give us some chance to put it out under those weather conditions. But we have to resist putting it out under the really favorable weather conditions. So that's a big cultural change. That said, this is still a monstrous issue that we created. Over 100 years, it's taken us to develop this problem. So it's going to take decades to fix this problem, and so we're going to have a period where we're trying to ramp up and scale up and tie fuels management to all the other things we do, and maybe even elevate the role of the fuels management.

Do some as, we…and on public lands we have been doing some of this, where we go in and do fuels management project that have none of those other objectives tied to it. We just needed to get a firebreak at the edge of town. And some of those are even paying off now for that. Get fuels into the mix, elevate fuels treatments to those ideas for land management. But that's still only going to be thousands of acres when there's hundreds of thousands of acres, millions of acres that are now out of balance, out of their normal fuel loading, normal fuel matrix. So wildland fire is going to do a certain amount of this work for us. And so again, we come back to that issue of do we always just wait until the worst weather conditions when we have no other choice, or do we partner with wildfire to do this work in the tens and hundreds of thousands of acres scale when the conditions aren't so bad?

Colleen: Well John, thank you for joining me on the Got Science? Podcast.

Bailey: Thank you for having me

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Sidelining Science: Shreya Durvasula
Editing and music: Brian Middleton
Research and writing: Pamela Worth
Executive producer: Rich Hayes
Host: Colleen MacDonald

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