50– The fire cycle: appreciating a fundamental disturbance, with Fire Ecologist Larissa Yocom

May 11, 2021 Utah State University Office of Research Episode 50
50– The fire cycle: appreciating a fundamental disturbance, with Fire Ecologist Larissa Yocom
Show Notes Transcript

Larissa Yocom researches how fire changes ecosystems and how those changes affect people. Larissa counts tree rings to learn how an area has burned in the past. She counts twigs on forest floors to see how an area would burn in the present. In this episode, Larissa explains the history of wildfire in the west, helping us understand fire as just another force of nature. Just like storms, we can't prevent fires from happening. But, mechanical treatments and prescribed burns give us some say in when and how an area burns. Decision-makers can use fire as a tool, reducing the negative and distractions effects fire has on people and communities. Listen to this episode and hear what happened in the past and what needs to happen in the present.

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*Wyatt, the host of this podcast, is in the process of replacing his former last name with the more spellable name—Archer. Questions about the podcast can still be sent to

Larissa Yocom: [00:00:00] one of the ways people talk about fire is we lost a thousand acres of forest in this fire. And that is not, that is not, not the case. Fire just resets the forest to an earlier stage. So you're going to get seedlings come back. This is not true everywhere, but I think the word loss. From virus is misplaced.


Wyatt: [00:00:25] There's something wonderful and lovely looking at big trees and thinking about how old they are and their history, and just being sad when they're like dead and gone, but also just like people having to face their own mortality. Maybe 

Larissa Yocom: [00:00:41] I think that there are a couple of things that I've thought about recently that.

Might have something to do with that. When is that we have pretty short lifespans compared to trees. And when you think about how long the Western us has been occupied, it's pretty short amount of time. So sometimes not even a whole fire cycle. So we, we, we think that what we see on the landscape is the way it's supposed to be.

And then when a change happens, It makes people feel upset, but, um, and that's because of our short lifespans, we're not able to see the whole cycle and realize that fires are a part of this longer term cycle. And the forest that we see today started after some disturbance, whether that was. Bark beetles or fire or, or something.

I'm Larissa Yokum. I am a fire ecologist in the wildland resources department at Utah state university 

Wyatt: [00:01:46] I am Wyatt Archer. And you could be trying to keep things the way they've been, but you are listening to this instead, a podcast from the office of research at Utah state university. Get ready to change. How you think about fire in the past few years, every Western state has been hit by at least one wildfire that was larger than 500,000 acres.

Well, every state, but Utah, in this episode, you'll learn what we have in common with other States. And what makes you taught different? You are going to learn about the history of fire management in the U S and Loris. It takes us to a time when native peoples used fire as a tool to guide the landscape into providing for their needs.

So get ready to learn why some forests burn the way they do and how a hundred years of fire suppression have led us to the fire conditions we see today. Fire it's inevitable. But luckily Larissa  is here to help us understand wildfire and to maybe even appreciate it. But real quick, I want you to subscribe to the instead podcast, tell a friend about us and find us on Instagram at instead podcast.

Now, back to my conversation with Larissa Yokum 

Larissa Yocom: [00:03:09] the forest that we see today. Started after some disturbance, whether that was bark, beetles or fire or, or something. 

Wyatt: [00:03:18] Cause like, I guess like I don't love fall. Yeah. It's pretty. But like, it's going to be ugly for like five months. 

Larissa Yocom: [00:03:24] I feel the same way that you do. And also I'm going to be cold for months now. 

Wyatt: [00:03:28] Yeah. And so it's just kinda like, yeah, cool. Whatever. Yeah. But like, I know enough to know spring is coming, you know, and I know enough that I started to realize I dread winter more than I actually hate it. And so like, we're used to seeing that life cycle, you know, of just like the seasons, I guess, but we're not used to seeing the life cycle of like a forest.

And that would make it difficult if it's your first fall. 

Larissa Yocom: [00:03:55] Exactly. I think that's a really good way to look at it. Yeah. We, the cycles, the natural cycles of some of these fire-prone ecosystems are longer than we are able to see in our life. Lifetimes. I liked the way you described it. Yeah.

Wyatt: [00:04:12] You mean just like the two sentence version of what you do as best he can.

Larissa Yocom: [00:04:16] All right. I study how fires affect forests and how we can best manage both forests and, 

Wyatt: [00:04:23] yeah. Um, and why is that important? Why should we care about that?

Larissa Yocom: [00:04:30] Well, fire is a essential part of forests worldwide. Um, really all ecosystems almost. And, um, we are seeing fires increase in, in importance in the Western us as they. Um, are burning larger and hotter year after year. And there's a lot of interest in how we can reduce the negative effects that they're having on people from smoke to watershed issues, to even catastrophes like homes burning.

Wyatt: [00:05:03] Um, and how did you get interested in this? How did like whatever, like sixth grader in a science class become a fire researcher?

Larissa Yocom: [00:05:10]  Yeah, so I was always interested in, in the outdoors. Um, I grew up in the Northwest and saw some of the timber Wars back in the eighties and, um, and then followed that through college and.

Um, some graduate school and then took a step back and thought about how I wanted to spend my career as a scientist and decided that fire and drought were the two big issues facing the West. So I got lucky enough to get to follow that. 

Wyatt: [00:05:37] Yeah. Where in the Northwest did you grow up? If there's timber Wars?

I'm guessing Washington. 

Larissa Yocom: [00:05:41] Yeah. Washington, I grew up on the West side of Washington. Um, it was during the time when logging was really starting to Peter out, mostly because a lot of the timber had been cut already. It was framed as environmentalists versus lagers. And I remember seeing signs out in front of people's yards and businesses saying this.

Family or this business it's supported by timber dollars. People were losing, you know, one of my best friend's dad was a logger and they were losing their jobs. And so, um, I don't know why I still remember that. I don't think most kids probably don't, but I decided I wanted to work. As a scientist to inform best management practices.


Wyatt: [00:06:23] Yeah. I guess that's how personal land management can be. Like it affects people's careers and their lives and where they live. And so like it, it's the interface of, of light of human life and what people want, how are people affected by wildfire? 

Larissa Yocom: [00:06:39] You make a good point, you know, and that's why I really love being in a natural resources college.

Um, we have really wonderful. Ecology research going on, but what a lot of people are concerned about is how decisions that land managers make affect people's livelihoods and lives and quality of life. We are lucky enough to be surrounded by so much, um, undeveloped land in the West, but. With that comes a lot of work to, to manage it well.

So there's really a lot of, a lot of ways that fire can impact people, even if they're not right next to a wild land interface. So even in urban areas, I mean, some of the big cities on the West coast last summer were just socked in with smoke. You couldn't see the sun, or if you did, it was this red ball.

Um, you know, people's careers, everything from recreation, people's favorite camping spots that they grew up going to year after year. Um, and then really importantly, I think watershed issues are huge. So there've been instances where upper reaches of watersheds have burned and it has affected the drinking water for millions of people.

So I think that's why, what drew me to it is I wanted to study an issue that. Anybody that I talked to would recognize as something worth spending time and money to, to figure out more, you know, to, to, to research. 

Wyatt: [00:08:09] Yeah. Yeah. So in multiple episodes, like with historian Lawrence Culver, and with Patrick Belmont, one of your colleagues, like they've talked about how the Western United States is just predestined to burn, like wildfire is like baked into the ecology of this region.

Can you tell me about that? 

Larissa Yocom: [00:08:30] Yes. Okay. So let's start way back at the beginning, billions of years ago. Um, it's there there's research that shows that as soon as there was enough oxygen in the air and enough plant matter to burn, which is also fuel fire started burning. So this was billions of years ago.

So on earth surface fire is a process like, like storms or other things that are. Part of this earth, um, coming to a little bit more recently than that we have, I, um, I've done a lot of work with tree ring records. That was what I spent my graduate degree doing. And so what you can do by looking at tree rings and fire scars that are formed on trees, you can.

See exactly what years fires have burned for centuries. If you have records long enough of in the trees. And that also comes through when you look at plant traits where there are species that have adapted to regular fire, their traits, um, make them ideally suited for burning every. Certain number of years.

And sometimes that's a short interval and sometimes it's every couple of hundred years, but they're know plants are adapted to these disturbed, what we call disturbance regimes. And there's also charcoal records over tens of thousands of years. So no matter what timescale you look at, you can see that fire is.

Apart of these ecosystems. 

Wyatt: [00:09:57] What other areas of the globe have the only place where fire is a part of like the environment that I know of is the Western United States, but where else is it? 

Larissa Yocom: [00:10:05] I, I wish that I could show you. I want to show you maps. Okay. So honestly, the Western us barely burns compared to some places in the world.

There are these really cool satellite maps that show burning going on around the world and the Western us. You see just a few little blips. So Africa. Burns a lot, um, both in wildfires, but also because people are using fire as a tool. Um, Australia has a lot of fire and actually some of the same wooey problems that we do.

So if that's more, what you're getting at, they have, um, they have pretty similar issues going on with, um, trying to figure out how to balance the needs of people on there and their fire-prone ecosystems, but every everywhere, um, You know, Siberia burns every once in a while. You'll see Russia will have a really big fire year and smoke will just blink it their country, um, in Western Europe.

So Portugal's Spain, France, all of those Mediterranean countries have fire-prone vegetation, it's Chaparral, which is the same thing you find on the coast of California and Southern California that burns very readily. Um, so, so it's, and in Mexico, I honestly, it's hard. There is not really. Um, many places that are not, um, They don't burn.

Wyatt: [00:11:25] Yeah. So we're not special. 

Larissa Yocom: [00:11:27] No, no. The problem that we have created for us, for ourselves, which is that we were so successful at suppressing fire for about a century. The better term is fire exclusion. We got rid of fire for so long. We thought we had it vanquished.

And so people moved right into the wild land, urban interface. Um, and, and I think for much of this, the 20th century, didn't have to think about fire very much. And now with climate change and this huge amount of fuels and heterogeneous homogeneous forest that we have, um, we just have really set the perfect stage for, um, a lot of problem fire.

The Western us is where. I think the most surprising that people that fire is still a force that we're going to have to deal with. 

Wyatt: [00:12:21] What. How did we exclude fire? How do we prevent fires from happening for that a hundred years. Okay. 

Larissa Yocom: [00:12:28] Okay. So it started with the finishing of the transcontinental railroads in the late 18 hundreds.

And what that did is it allowed livestock to be grazed in massive numbers in the West and shipped back East to a market. So there weren't enough people here to hundreds of thousands, millions of sheep out on the, on the. On the landscape. Um, but once those railroads were built, they could ship sheep back in huge numbers.

And so basically what happened is, and this is really most relevant in those Ponderosa pine and other frequent fire systems. Those animals ate all of the fine fuel that served as the, as the fuel for those frequent buyers combined with some logging, other changes to the ecosystem. Um, what happened is a huge crop of new trees.

Came in. And so instead of having these grassy under stories that would burn regularly, you got this crop of new trees that were really thick and dense. Um, they didn't, they didn't burn for a couple of decades and that allowed them to get established. And so the forest that used to be open. What they call park-like and grassy are now dense thickets of kind of scrawny trees.

There's they're much thicker than they were before. And so when a fire does occur, it can get up into the crowns and, and, and race through with a tremendous amount of fuel that has built up over, over a century, livestock logging. And then. Um, starting in about the thirties, we started to get fire towers where lookouts were stationed to look for smoke.

There was what was called the 10:00 AM policy that got put in place. So every fire was supposed to be out by 10:00 AM. The next day, really aggressive firefighting. And then after world war two, all of those planes and people came back from the war effort and were put to use with firefighting. And it really became almost a military.

Style war against fire. They got really good at it. Very effective at putting out fires very quickly. Smoke jumpers became a thing. Um, and this kind of industry built up that hadn't been there before. So, so suppression got really good in the fifties. Um, but before that it was those animals and, and some logging as well.


Wyatt: [00:14:47] So now. Getting a fire under control can be incredibly difficult. Is that because the fires that were being suppressed in the fifties were smaller because the timeline of suppression was still shorter. 

Larissa Yocom: [00:15:00] Yeah. So you're asking why we're not able to control all the fires today, whereas they did do a good job of that in the fifties.

Yeah. That's a good question. I think that that's probably true to some Cate, some degree that the fuels were not as thick as they are now and climate I think has to do with it too. So some of the, you know, California's I just saw a presentation the other day, five of six, five of the top six largest fires in California's modern history burned last year.

That is. Because of the hot, dry conditions that we're seeing. So I think is it's, that's, it's a, that is a good question. Whether it's fuels or climate and it's both, but I think in recent years, climate is really starting to dominate the changes. 

Wyatt: [00:15:47] Tell me about. The fire situation here in Utah, what makes it unique?

Larissa Yocom: [00:15:50] 

Okay. So when I got here, which was about almost four years ago, now I had a similar question, which was why Utah has not had, um, a 500,000 acre fire. Yet most States surrounding Utah have had that at least in forest city, the biggest fire in Utah history is a grassland fire. Um, but Arizona has had to. Half million acre fires, California clearly has had million plus acre fires.

So, and you know, Washington, Oregon, Colorado, Idaho, Montana, all of them have had these. Super mega fires. It's not a term, please don't use that, but it hasn't. The biggest one that we've had is somewhere under 200,000 now in the last couple of years. And that's still very big, but I've been wondering whether it's luck or whether there's some reason that Utah hasn't had those very large fires.

I think part of it is that. The topography in Utah, doesn't allow for fire spread as easily. As in some other places, we have very steep topography and fires. Um, but that might not be a good answer actually, because there are places where a fire could get pretty big. So it might be luck. Um, I think also we have a shorter fire season than in many places because we have the high elevation forests where the snowpack lasts till June.

So that could be part of it. But I do think that's going to change. It's going to change. It's already changing. I mean there's yeah, the snowpack the ski resorts know this already. There's snow pack has been declined being for a couple of decades. We are due for some more or big fires in Utah. 

Wyatt: [00:17:34] Definitely.

Yeah. Yeah. Take like. Logan Canyon or Cottonwood Canyon for settler influence. How often, where maybe those like going up in flames? 

Larissa Yocom: [00:17:44] That that's actually a really good question that I don't have a good answer for because there hasn't been enough work done on that. There hasn't been a fire ecologist in Utah focused on that.

Really ever. I actually have permission to take it out there with a chainsaw to go cut some fire scars the summer. And so we know so much more about the Southwest and even, I mean, I did all my PhD work in Mexico and I feel like we know more about that too. Mostly Douglas firs, what you start the first Connor for UC as you start driving up the Canyon.

So some of the Douglas verb, maybe every. But you probably never went up in flames all at the same time. In the same year, it was probably patchy. So maybe every couple of decades you have a fire that took out some of it. And then at the higher elevations probably longer. So maybe every couple hundred years in the spruce and the fir, so it depends on the elevation and yeah.

Wyatt: [00:18:33] So when we have fires, like. They're not patchy. They're huge, right? Until, um, it can be contained or whatever, what allowed those fires in the past to be patchy. 

Larissa Yocom: [00:18:46] Exactly what you just said. So historically, if you had patchy fires, they would form patches of young vegetation that didn't burn as easily. And so it was kind of the self-limiting process where a fire would burn a couple of decades later.

Another fire would burn, run into that young moisture. Rich. Young vegetation and maybe burn itself out. So regular fire probably helped limit subsequent fires. So it, instead of having this mountain range full of. Homogeneous vegetation that there's really no break in. It was, it would have been more broken up by previous disturbances.

Wyatt: [00:19:25] So it's just kind of when fires were happening regularly, there just wasn't as much fuel that was connected. 

Larissa Yocom: [00:19:32] Okay. So this is why it's really hard to get. Across fire ecology in a soundbite, you really have to think of what the species are that are there. And there are different types of historical fire regimes.

So the poster child of frequent low severity fires is Ponderosa pine. And that's the species that you find in Arizona, New Mexico, down into Mexico, Southern Utah, but it also goes into Colorado and Eastern Oregon and Washington. So it's pretty widespread spread species, but that. That tree is known for having very frequent buyer historically, and a grassy understory a lot of times.

And so in some places that those forests would burn every three to five years or maybe every 10 years very frequently. And it would just, those fires would burn along the surface. They're called surface fires. They'd burn in the grass and not really usually kill very many of the overstory, the large adult trees.

Maybe leave a fire scar, which is how we know what year the fire burned and then, um, burn again a few years later. So those that's a type of fire that, you know, it probably wouldn't have left patches. It would've just been maybe burned for a couple of months throughout the summer. Take off the top of the grass.

The roots would still be fine. The grass would re-sprout greener than ever. Um, and it would burn again. Subsequently the poster child on the other end of the spectrum is lodgepole pine. And that's the tree that you find the Northern Rockies it's, um, there's a lot of it in Yellowstone national park. A lot of it was what burned in the 1988 Yellowstone fires that, you know, made headlines around the world.

And so that type of fire historically would have burned in patches maybe actually in pretty large. Patches that those 1988 fires, maybe weren't historically unprecedented and those fires would have burned, um, every couple of hundred years. Very high severity. They would kill all of the trees, but those trees have these, what are called serotinous cones, where they open up with the heat of the fire.

And afterwards new lodgepole Pines are just, they come up like crazy. So that's a different type of fire regime. And then there's a whole spectrum in between. So. So these kind of the patchy mosaic that I was talking about, that's probably something like you'd find in parts of Utah in some places in Southern Utah, for example, and on the foothills of the Uintas, the low slopes, we have Ponderosa pine.

And so those fires fires there would have burned at low severity pretty frequently, especially when you have native American people who. Set fires for all sorts of reasons.

Wyatt: [00:22:22]  So does that help? Does that, I mean, no, 

Larissa Yocom: [00:22:24] I'm excited. Okay. I mean, that's why I can't, it's really hard to just the mosaic patchy thing is not, it's only in some areas.

Wyatt: [00:22:34] Yeah. Yeah. Um, what are like the physical features that make lodgepole Pines and Ponderosa Pines burn differently. 

Larissa Yocom: [00:22:43] Great, great question. Okay. So this, yeah, because they are kind of the poster threes of these different fire regimes. Um, they have very different characteristics and so Ponderosa Pines tend to have very thick bark and that insulates them from those surface fires.

So the. He doesn't get all the way to the Cambium, which is the living cells, right. Between the bark and the wood. And. They also do what's called self pruning. So they drop off their lower branches. So any kind of surface fire doesn't get into the needles and isn't able to spread to the, to the crowns. So those two things are characteristics of Ponderosa pine that make them ideally suited for those low severity.

Frequent surface fires. Lodgepole has very thin bark. It doesn't invest any energy into thick bark because thick bark wouldn't save them from a crown fire. Which is a fire burning through the canopies and they don't self prune. So they have branches that are, that can be kind of low to the ground. Um, And then they have this serotinous cones, which makes them be resilient after a fire.

So the trees that are actually there usually don't survive a fire when it happens, but their offspring is ideally suited to come back after the fire. 

Wyatt: [00:23:58] Um, new can loo new lodgepoles like sprout from like the roots of fired ones. Are they done? No Pines? 

Larissa Yocom: [00:24:03] Can't there are a few species of Pines that can resprout the trees that can resprout in the West that are.

Great are coming back after fire from the roots are Aspen and Gambel Oak. Those are a couple of, um, species that can read. 

Wyatt: [00:24:20] So you mentioned that native peoples would set fires for all kinds of reasons. Tell me, give me some of those reasons or all of those reasons. 

Larissa Yocom: [00:24:27] Yeah. So, um, And I can come back to this.

If, if I forget some things I might email you, but, um, so they would burn for hunting. Sometimes they would burn to increase the forage available to game animals. So like I mentioned, grass comes back greener after fire. And so if they burned, they would, you know, a place where animals might want to come and it would be it, uh, a hunting opportunity.

In other cases, they would burn and to drive animals. Physically at the actual moment into, for example, a box Canyon where they would be trapped. Um, they would also burn for warfare apparently. Um, they would also burn for some of the same reasons that, um, prescribed fires are set today to reduce fuel hazards.

So to reduce the likelihood of a wildfire burning their village, um, also to reduce pests. Like grasshoppers or ticks, things like that. And actually what's interesting is that people around the world still burn for many of the same reasons. So there are, um, places in, in other, on other continents where fire is still used as a tool every single day.

And there's the, some of the same reasons there, um, burning, burning vegetation. Another reason is, uh, travel ways. So if you burn, it's much easier to get through. Um, The vegetation without, you know, running into a snake or something else dangerous. So yeah. Lots of, lots of reasons. 

Wyatt: [00:25:55] What makes would they use to like limit the scope of a fire?

Would they like, Oh, we'll burn in like mid may so that it doesn't go too crazy or 

Larissa Yocom: [00:26:04] that's a great question. And I don't know how much information there is on that kind of on that. Um, I, I, I suspect that because there was just what much more fire than there is on the landscape today that some of the, you know, the fires would be somewhat self-limiting just by running into previous fires from other years.

But I also think that there were probably instances where fires really did get going. I don't know if they, they probably, you know, they didn't have, um, Fire lines necessarily. Yeah. So, um, one other thing I'll just mention in case you're interested is that they would also burn to promote particular plants.

So there are plants that do really well with fire plants that they use to make baskets, for example. So they would burn or Oaks in California, they would burn to promote those plants so that they'd have their food resource or their. Basket making resource, um, in, in more quantities than they would without fire.

And I'll also mention that several tribes around the West are restrengthening their fire programs. So some of the tribal lands in California in Arizona for example, are just using fire more and more, um, and teaching, uh, people about their use of fire. Um, and there's a lot of interest in that right now, but to use that knowledge, uh, on a larger scale.

Wyatt: [00:27:25] historically, how were fire started? I know today a lot of them are caused by gender reveal parties or, um, poorly maintained power infrastructure. How were fires initiated before settlers came? 

Larissa Yocom: [00:27:41] Okay. So lightning is a big cause of fire. It probably depends on the location. What proportion.

There was certainly enough lightening in lots of areas that lightening alone could have set most of the fires, but we know that people also were setting fires. So yeah, one thing to remember though, is vegetation has to be dry enough and plentiful enough to burn. So even if someone set a fire. It may not go anywhere.

And so I think that that is the more than ignitions, the conditions for burning more, the more limiting factors. Yeah. 

Wyatt: [00:28:17] Yeah. So what role does prescribed burns have in controlling fire and how can that. Eight us in the future. How can we use that as a tool like the native Americans and people in other countries do ?

Larissa Yocom: [00:28:30] Prescribed fire is really one of the best tools that we have to reduce fuels and try to influence the way that buyers were will burn in the future.

Fire behavior is controlled by three factors, and this is called the fire behavior triangle it's weather, typography, and fuels. So whether that means in hot, dry, windy conditions. A fire is more likely to move quickly and burn hot. Um, in terms of topography, fire moves more quickly uphill, for example, and then fuel the type of fuel, the amount of fuel, how wet the fuel is.

Those things are all factors in the way that a fire burns as well. When you think about what people can control fuel is the only leg of the triangle that we have any influence over. We don't control the weather and we can't realistically change typography. So. Prescribed fire and McCain. What we call mechanical treatments are our options for how to change the fuel complex.

And so prescribed fire can reduce the amount of surface fuel. In a surface fire prone environment. There also are high severity prescribed fires where managers typically on a smaller scale will set a crown fire and actually burn a patch, a large patch of trees and try to kill them to promote new growth, for example, and again, break up that landscape.

And then there's also things like thinning or other treatments that can be done with chainsaws or heavy machinery where you convert canopy fuels to surface fuels, or you try to just reduce the amount of fuels. And I'm sure everyone in Utah has seen piles being burned. So a lot of times people will cut trees or shrubs and then pile them up and maybe burn them in the winter.

And again, that's a fuel reduction technique. So those are all very good options. The one that you can get the most acreage done quickly is a prescribed fire, but also there's another idea that's coming out in more and more with more and more support. And that's, what's called managed wildfire where a lightening ignition is used to try to get some benefits out on the landscape because, um, Really, those are the ones where you really get the most acreage.

This is another example of, um, native American tribes taking the lead on this kind of thing. There's, um, a tribe in Arizona that has burned almost their entire tribal lands. Now, um, in these managed wildfires, I think their biggest one was 70,000 acres. And typically those are occurring in conditions that are not the most extreme.

That's the key. So. Wildfires that are out of control where people really honestly don't have many options to control them are occurring in the most hot, most dry, most windy conditions. If it occurs a little bit, you know, and shoulder season. May do some really good work without the, as much of the risks as if they occurred at the peak of the fire season.

You know, I think managed wildfire is not even the right term anymore. I think that they're all wildfires. Um, but there's another reason to not. Immediately suppressed fires as small as possible. And that's firefighter safety back off a little bit, get to a safe place to suppress a fire and allow it to come to that safe place.

Yeah. And so there's, it's not just for resource benefits, which is what they call it now. 

Wyatt: [00:32:03] What are people's reservations to wildfire? I remember hearing my dad talk about the 1980 Yellowstone fire kind of frustrated by that instead of it being put out as quickly as possible. So I guess tell me the timeline of.

Introducing the ideas of letting fires, burn and prescribed burns. And then tell me about people's like reservations towards that. 

Larissa Yocom: [00:32:23] Yeah. Okay. So we're going to back up again. And, um, there was a debate back in the late 18 hundreds, early 19 hundreds about. Fire. There were people who thought fire should be used as a tool, you know, settlers were using it to clear land to plant.

And then there were the people that thought that fire was a waste of our natural resources. People viewed themselves as stewards of the land, but also it was like a God given natural resource that they should protect from this kind of evil. Yeah, um, of fire. And a lot of my information comes from Steven pine, who is a fire historian at Arizona state university.

So in 1910, there is what was called the big burn. Several million acres burned across the Northwest and Idaho and Montana and smoke reached across the country. And it was huge news. So much old growth timber was burned. People were killed and whole towns were burned. And that was the event. That settled, this debate and.

Made the general public and decision makers come down on the side of fire protection. So the forest service was formed in the early 19 hundreds, and they were pretty immediately tasked with fire protection with, you know, very few men and resources. Um, but that was some of the, you know, what people expected is that the timber resources would not be burned, but would be protected from fire then.

There were still some, a few voices of dissent about this that noticed that native Americans had successfully been using fire for hundreds of years. Um, but they were drowned out. Um, and I actually had an undergrad student who did a directed reading semester with me, and we read a lot of these old papers.

There were so interesting. It was fun. Then in the, in the forties and fifties, a couple of foresters, um, brought back the idea of prescribed fire and started. Practice experimenting with prescribed fire actually on, on, um, tribal lands, um, in Washington. And, um, I think a little bit later in Arizona and then in the seventies, the park service started reintroducing fire in, um, Yosemite was one of the first places and then Yellowstone and Yellowstone.

They. Would try to let fires burn and they wouldn't really do much. They would burn maybe a dozen, maybe a couple hundred acres. Um, and so they were, they. Started to think that they were not, it would be difficult to get a lot of acres to burn. So then the 1988 fires happened and that shocked everyone that shut down the, um, fire use program for a while.

So then in the nineties, I think is when it started to reemerge again and the Southwest, um, and elsewhere, but there were people that put in a lot of work, some of the fire. Um, scar studies were instrumental in, um, showing how frequent fire was historically. Um, and I think, you know, over the last 20 years or so, it's really, um, increased to the point where a lot of support is out there now for prescribed fire.

I think that the idea of a managed wildfire is still a little bit. Yeah. 

Wyatt: [00:35:47] Yeah, less supportive. If you had a magic wand and your job was to just like change how you taught, handles fire, you were given like complete control. What things would you start doing? 

Larissa Yocom: [00:35:58] I mean, this is why I'm doing this interview is to start to have people realize that fire is inevitable.

It's an inevitable part of our ecosystems. It will burn and we. Have a little bit of a choice in how it burns and when it burns, but not whether it's going to burn. And so in that light, I think if I had a magic wand, I would convince people that we need buyer in order to prevent disaster fires. And so I would try to increase the amount of support for their land managers who know all of this as well as I do.

Um, Public support for doing things like prescribed fire, managed wildfire. Um, we need more funding for those prevention measures. Most of the forest service budget budget now has gone to fire suppression away from the preventative management. And that's, you know, it's not the district Rangers fault or any.

Person charged with managing lands in Utah. It's at a much higher level than that. And yeah, it's, their hands are tied. 

Wyatt: [00:37:12] So prescribed buyers, thinning, like all of these techniques are being done. But you just said, it's not on a scale that's needed. What is the scale that's needed? Is it five times as much, 10 times as much, 

Larissa Yocom: [00:37:23] you know, the scale that's being done, we're just falling behind further and further every year.

So what we have done so far is not making a dent and in fact, isn't even enough to keep up with the need. So it's probably, it's probably 20 times as much or something. Yeah. There's numbers out there, but yeah, it's better than nothing, but it's not barely. 

Wyatt: [00:37:39] Yeah. Yeah. Bummer. So, if I were to follow you on an interesting day of research, what would I see?

And then you can tell me about a boring day of research later. 

Larissa Yocom: [00:37:52] I think that some of the exciting research would be, um, one of the things that we've done recently is we're looking at. What species are coming back after fires in Utah and beyond. And so, um, one of the interesting things that we have looked at in the last couple of years is Aspen regeneration.

Historically, it was thought that Aspen's pretty much only re sprouted from the roots after a fire. But what we have recently discovered is that they also come back through seed. So they, they send their cottony fluffy seed across the landscape 

Wyatt: [00:38:28] They look like little caterpillar worms.

Larissa Yocom: [00:38:28] Yeah. And it can fly miles and it can land in places where there weren't Aspen before.

And so we've discovered Aspen seedlings are everywhere. They are much more common than. We thought. And so it's actually exciting to find an Aspen seedling in a place where you can't actually see an adult Aspen. And so I had a student that went to 15 fires last summer and looked for Aspen and he found seedlings, not suckers.

Suckers are the term for what comes back from the roots. He found seedlings in 12 of them across. Most of them, most of those fires were in Utah. So that's an exciting day. Although even then the. Specific work you're doing is pretty tedious. You're hunched along with your face at the looking at the ground.

Wyatt: [00:39:16] Yeah. Yeah. What else are you doing when you're outside research? 

Larissa Yocom: [00:39:20] So we're sometimes we're measuring fuels. Um, so right now we have a project that there's this idea that Aspen might be a nice, um, way to protect. Wild land, urban interface, communities from fire firefighters and managers have seen it multiple times.

Um, where fire in in the crowns of trees will drop to the ground and either go out or burn as a surface fire and be easier to control when it hits an Aspen stand. We are researching the details of that. How big does the Aspen stand need to be? How pure does it need to be? Um, are there age considerations to, you know, are there other fuels the understory fuel does that matter?

So we have lots of, we're kind of working on that question from many directions. We've sent out a survey to managers to ask them and what they've seen, we're measuring fuels and fuel moistures and Aspen and conifer forests. Um, we're looking at. Historical fires in Utah to see if burn severity is lower, where Aspen cover was higher.

So that's kind of an interesting line of research. I think that, um, I'm excited about. And so field research for that project will include, um, measuring how much fuel is in a particular spot, how wet it is and what kind of species are there. 

Wyatt: [00:40:46] How do you measure fuels? Do you like just. Square off a section of ground, take everything from it and put it in a blender, or like what 

Larissa Yocom: [00:40:54] you can do that you can, you can collect it all and weigh it.

But there are also established techniques that translate a particular method in the field to loads, which is that's how fuel is measured is in biomass. And so, or by weight. And so you lay out a tape on the ground, um, And it's, uh, it's 75 foot tape and you walk along and you count how much fuel is in different classes.

There's different size fuels that people talk about one hour, 10 hour, a hundred hour and thousand hour fuels. And that refers to the size of the fuels. 

Wyatt: [00:41:27] Is that like, Oh, this tree is this tall. So that's, there's a 10 hour fuel here. 

Larissa Yocom: [00:41:31] No, it actually has. So when our fuels are, um, up to a quarter inch, so little twigs and then a 10 hour is quarter to one inch and then a hundred hour is when.

One to three inches in a thousand hour fuel is anything bigger than three inches. So those are the fuels that are on the ground. Like those surf, like twigs logs, things like that, dead dead. Would he stop you on the ground? Yes. And then for, for things like grasses, then yeah, you can either. The one, yeah, you could clip all the grasses and weigh it and weigh it back in the lab once you've dried it out.

So, you know, how much, how much actual fuel is there? So most of the time, what you're measuring is of Woody fuels on the ground and any kind of forest it system, because that's, what's going to what they call, carry the fire. That's what the fire is going to be able to spread through. So that's how you think about fuels is what is the dominant type of fuel, whether it's dead, Woody fuel.

Why verbatious fuel, which is like grasses and Forbes. If it's, you know, you have to think about how the fire, what is going to allow it to continue to spread. And so a lot of times in forest, it's that Woody dead material, the most important thing. 

Wyatt: [00:42:39] Yes. Because you can see a forest and be like, yeah, there's a forest there that'd burn.

If things got hot enough and big enough, And the fuels on the ground is what gets it hot enough and big enough. 

Larissa Yocom: [00:42:51] Exactly. Yes. It's very rare for a fire to be able to burn through the canopy of trees without a lot of fuel on the ground, because the heat from the fuel on the ground is what heats up the canopy fuels and allows the fire to move through the crown as well.

Wyatt: [00:43:07] Um, tell me more about. Grassland fires. Like we've talked about tree fires. That's like the kind of fires we think of, but what happens when like miles and miles of Sage brush burn up or, you know, how does that 

Larissa Yocom: [00:43:21] okay, so grasslands are very fire prone. And, um, historically, um, fires would have burned and grasslands, EV you know, some places can burn every year, every couple of years, every few years.

So it's thought that most of the mid, you know, the Prairie's of the Midwest would have burned pretty regularly. And there've been experiments to show that some of the native grasses actually will start to go in decline if they're not burned every, every couple of years. So a lot of the prairies of our country have been turned into wheat fields or other, you know, farm fields, but in the few remaining pockets of Prairie, they do use fire as a regular tool to, um, to promote those native grasses.

In Utah. And some of the other places that have been, this is a whole other topic, but in places that have been invaded by non native grasses, like cheatgrass, that's a different story. So in places where sagebrush is dominant at this point, fire can be detrimental because it kills. Sagebrush and cheat grass, which is an exotic invasive species thrives with fire.

And so it's called this called the grass fire cycle. And basically what happens is cheat grass burns very easily. It thrives with fires. So once you get fire into a system like that, it can burn. All the time and sagebrush doesn't have time to regenerate between fires. So in Utah and a lot of the great basin fire is suppressed for very good reasons because, um, once cheat grass gets into a system it's really hard to get out and it's really hard to get sagebrush reestablished.

So invasive species are a whole, it's a whole other complication. Um, 

Wyatt: [00:45:11] one other random question, sheep eating. Like fuels and then sending those sheep back to back East for whatever was something that was done back in the day. Is there. Is increased grazing, like another tool that could be used for fire management today.

Larissa Yocom: [00:45:27] There are, um, there's kind of a renewed interest in that. Um, it's called targeted grazing and especially goats. Goats will eat anything. So putting them on like a Chaparral hillslope above. Homes in California, for example, might be a good solution, especially for places where, you know, close to communities where you really want to prevent fire.

But again, I would caution against trying to eliminate fire from all landscapes, because that's going to be counterproductive in the end. So that would be a tool that might be useful, um, on, you know, in the wild land, urban interface, for example, all, you know, prescribed fire and thinning and all of those.

Fuel treatments. You know, there are arguments that those should really only be used use to reduce the severity of fire. So reduce. The likelihood that it's going to get up into the tree canopies or the likelihood that it's going to be out of control, but we really shouldn't focus as much on acreage as a metric of success.

So you see a large amount of acreage burned in a particular year. Great. But really we should focus more on the neck, you know, actual negatives, which are homes, burned or watersheds. Um, Impacted, 

Wyatt: [00:46:39] what should the metrics of success be then? 

Larissa Yocom: [00:46:42] Yeah, I've been thinking about how, you know, coming up with a new metric for fire seasons, the separates out the ecological from the human impact.

So acreage alone is not a good metric because fire can have ecological benefits. So if we think more about maybe the costs, the amount of money we've spent on suppression in a particular year, or buildings burned, or, um, Smoke impacts the numbers that are more directly tied to human outcomes. 

Wyatt: [00:47:10] Like what are some of the funniest like research moments?

You're still excited about that you got to do. 

Larissa Yocom: [00:47:17] I'm getting out to a place, you know, where, where I've figured out. I need to go based on random sampling, for example, you lay out a grid and then you use your GPS. Unit to navigate to a point on the ground that in your office was just a random spot and you get there and you realize that there's no other reason you would have ever been able to, to go to that spot.

And maybe you see this amazing view or you. See, you know, something along the way that you wouldn't have gotten to see otherwise. And I, I, I love that part too. I just love where it has taken me physically. And the, um, I think what I've learned about how big the world is because of those, those moments. Um, I think I always appreciate those moments.

Wyatt: [00:48:03] That was my conversation with Larysa YOKA. If you want to learn more about wildfire, you can RSVP for her virtual research landscapes event. At research, there will also be a link in the show notes. This episode was produced by me, Wyatt Archer. If I had a lot of help on past episodes from Nick Vasquez.

And I want to tell him congratulations on graduating next off to some big city. Nick, thank you for your friendship and thank you for helping me make this podcast. As part of our work in the office of research at Utah state university.