Smokey the Bear is on the outs with ecologists. This fuzzy forest ranger is famous for his admonition, "Only you can prevent forest fires," but many scientists are asking if that's a good thing. Some pine cones, for instance, can't open without the tickling of flames, and America's grasslands would be woodlands without fire to clear the trees, says ecologist Meg Krawchuk of the University of California, Berkeley. But just as science adopts a complex view of blazes, global warming is set to reshuffle where and when fires spark up worldwide.
Krawchuk comes to fire not as a pyromaniac but as a pyrogeographer, exploring blazes over space and time. Fire studies gained immediacy in 2009 after hungry infernos in Southern California tore through hundreds of thousands of acres near major cities.
But changing rates of global fire won't just threaten homes and lungs; they also may reshape plant and animal communities, Krawchuk says. She took 16 different climate forecasts and compared them to historic fire rates and plant ranges across the planet to get a view for how global warming will affect global fire. And even though Earth is getting hotter, she says fires won't light up everywhere. Some areas will feel the heat, but others may see blazes drop. We need to understand fire's future, Krawchuk says, to keep our planet's wild spaces from going up in smoke.
SciCom's Daniel Strain had some burning questions for Krawchuk at the February 2010 meeting of the American Association for the Advancement of Science in San Diego.
How does someone get into a field like pyrogeography?
It's becoming an interesting term that has popped up over the last year or two. Every time I say pyrogeography, people get really excited and say, "Oh, that's really neat," "Oh, I like that idea." My interest has always been not specifically in fire but more ecosystems, and I just happened to be studying fire as a disturbance process.
So, your main interest is in forces that disturb habitats, and fire happens to be one of those forces?
Strangely, one that I think is underappreciated in terms of how it affects systems.
How so?
There's a longstanding debate of how much fire actually plays a role in where we see different ecosystems. There's often an argument that it's not fire that changes this. It's differences in soil, differences in precipitation, and fire just happens to be there, but it's not the driver. However, we're beginning to find more strong evidence that fire is the driving factor.
So, that changing understanding led to this new field of pyrogeography?
It's not necessarily a one-person idea, but the time was right for pyrogeography and global thoughts of fire.
"You've been having fire in Southern California forever. I don't know why every single year people get excited and say, 'Oh my, why is this happening?'"
What made the time right? Was it scientific developments, or large fires like the ones we've seen recently in Southern California?
You've been having fire in Southern California forever. I don't know why every single year people get excited and say, "Oh my, why is this happening?" That's not necessarily the driver for it. It's more the technology and data becoming available.
Do scientists get into pyrogeography because there's a certain excitement—a Backdraft interest in fire?
For me, I started studying the environmental causes and ecological outcomes of fire before I ever saw a "live" fire—something more than a campfire. Campfires illustrate how enticing a fire can be, but a live wildfire or forest fire is a completely different beast from a campfire. I'm certainly drawn to the beauty and power of a wildfire burning. My feeling is that those who are really drawn to fire in a pyromaniacal way end up working with it more from an operations perspective, like firefighting.
There's this popular notion that fires are chaotic, unpredictable. The whole field of pyrogeography seems based on the opposite assumption.
Certainly, there are very strong climate drivers of where we see fire. When you're driving down the highway and you see red or green signs, those are based on fire prediction systems that integrate preceding weather and the current day's weather. The idea that there's a relationship between climate or weather and fire is not novel, although the idea of scaling up in extent to look at the whole globe is.
What roles are humans playing in causing fires in locations where we didn't see them before?
Within the tropics, they're actually breaking up the micrometeorology [weather close to Earth, such as forest fog, rather than high in the air column] that makes the area so wet. Once you've opened up the canopy, the moisture is able to escape, and burning is able to occur. If you look at Africa, most of that is human burning. It has been for hundreds and hundreds of years. But you still see such a strong climate signal. Yes, humans are forming these ignition patterns, but it's all within the window that climate provides.
I've been seeing a resurgence of Smokey the Bear public service announcements recently. Is that a bad thing?
The Smokey the Bear phenomenon is really strange. It led to a lot of suppression of fires back in the 1960s and 1970s, which led to fuel accumulations that were beyond normal levels. Those places are going to burn regardless. What you're doing is pushing it off so that when it does burn, it'll probably be more intense. I wouldn't say Smokey the Bear is coming back. If anything, I think they're trying to modify Smokey the Bear to have a message of thinking about fire, rather than all fire being bad.
In Yosemite National Park, they've had a very long fire use program. When lightning fires occur in the park, they let them burn if they're not a threat to any humans. We need systems to start having fire back in them again.
It's a strange idea, but how can fire actually help natural communities?
When you think of the strategies of certain species, some are light lovers. They love open space. In the absence of fire, species that have those capabilities might not be able to compete. You might end up with a change in the composition of a community.
And this becomes an interesting debate: What is it that we think is natural? What effects did First Nations [indigenous Canadian tribes] have? We try to emulate historical patterns, but we don't know the extent to which historical patterns are human-caused or whether they're climate generated. Those questions of what we want these landscapes to look like are very philosophical.
How might changes in fire regime affect natural communities?
If you end up burning more often, you're likely to burn the regenerative individuals of certain communities, so that it will be unlikely for them to reach maturity. The example people have seen on the other end of the spectrum are the woodland-savanna boundaries, where frequent fire maintains a grassland system. In the absence of fire, trees are able to establish. Once the trees are established, the fire that does come through is more of an understory fire, and it doesn't kill the trees. That will trickle down to animal species.
Your model predicts that fires will go up in certain areas but drop in others. That seems counterintuitive.
On first read, it might seem counterintuitive, but not when you think of the relationship between climate and productivity in plants. When we compared parts of northern Australia in the near future to the distant future, we saw that there was a likelihood of fire increases between 2010 to 2039. But when we looked at the end of the century, there was a decrease in fire projected for that area. As it becomes drier, you burn more. Then you go through this transition period where you'll have less grasses and less shrubs because it's more of a desert. Even though the temperature might be warmer, you no longer have anything to burn there.
So is that the big factor in controlling fires, how much vegetation you have?
Definitely biomass [the total greenery in an area]. Because without biomass, there's nothing to burn. The crazy/frustrating thing about fire is that even though we talk about biomass and then climate, you can't really ever untangle those two. Climate really influences where biomass occurs.
Do you do field work to balance your modeling? Is it relaxing to go to Yosemite after spending a lot of time at your computer?
I like to get out to smell the numbers, as I like to say. This includes participating in prescribed burn projects—actually setting forest fires and watching them burn. In many ways, all my outdoor excursions end up being somewhat like field work. As an ecologist, I am constantly asking questions, such as what is that tree? Why are those plants living there? How old is that burned patch of forest?
To use an analogy, it seems like most of your work is taking a wide-angled lens to fire. Once you have that wide picture, do you plan to then zoom in?
One of the neat projects that I'm working on now is in China. There's been a long fire suppression policy there. They haven't recognized the role of fire. The Nature Conservancy from China has approached us to start looking at what fire regimes in China might have been. There are hundreds of fire ecologists working in the United States, and there are still so many things we don't know. So going to a place where there are very few people looking at fire becomes a very exciting and enticing idea.
Is there a morbid excitement among ecologists that climate change is no longer hypothetical?
It's scary that we're entering what was once the future. I think there's a fear now that we'll lose a vision for the past. Living in your neighborhood, you forget that it used to be something very different because it changed so gradually. We're getting further and further away from the world before all these climate change projections.
What sort of relationship or feedback is there between fire and climate?
It depends on where the fire is. In boreal systems [forests just below the Arctic circle], you end up burning the carbon dioxide. But then you have regeneration through photosynthesis taking up all the carbon. You move into places where the land use changes—specifically the Amazon, where you're taking forests that don't burn very often and you burn that biomass. In that case, you're not regenerating any of that structure, so you end up with more of a net emission of carbon into the atmosphere. The effect is largely unaccounted for in any of the climate modeling that goes on. It's an exciting unknown and a worrisome unknown.
I guess it's scientifically exciting.
[Laughs] Yes, and it's worrisome from a cultural point of view and from a global population point of view.
Daniel Strain, a graduate student in the Science Communication Program at UC Santa Cruz, earned his bachelor's degree in ecology and evolutionary biology from UCSC. He has worked as an intern at the UCSC news office, the Salinas Californian, and the Woods Institute for the Environment at Stanford University. This summer, he will write and produce multimedia materials for the U.S. National Park Service in Point Reyes, California.
© 2010 Daniel Strain
