Several thousand acres of forested land around Flagstaff received prescribed burns in recent weeks. KNAU’s Melissa Sevigny spoke with fire ecologist and director of the Arizona Wildfire Initiative at Northern Arizona University Andi Thode about why it’s critical to take advantage of a narrow “burn window” offered by cool, rainy weather this spring.
We’ve been seeing a lot of prescribed burns in the area recently. I wonder if you can talk about: why now? What are the conditions that make it a good time for a prescribed burn?
A lot of what it depends on is our fuel moistures, which means the moisture in the vegetation on the ground, and also the dead vegetation on the ground, so logs, sticks, things like that, how much moisture they have, and how much moisture we have in the grasses. It’s a balance between not having too much moisture so that things actually burn and carry, but having enough moisture that things don’t take off.
So it’s a fairly narrow window, often, in which you can safely put fire on the ground?
It is. And this is right before our wildfire season, and so sometimes it’s harder to actually do prescribed fire in the spring, in that sense, and it’s nice when there are windows like there are this year, for managers to be able to do a lot of good on the ground.
Okay, so tell me about how this helps reduce the risk of big wildfires.
Having more frequent fire or prescribed fires come through when weather conditions are more amenable to having low flame lengths, so 1 to 2 -foot kind of flame lengths—those flame lengths don’t climb up into the trees, they don’t move up the ladder fuels and cause crown fires that can run through the crowns. And so doing that frequently, having less surface fuel, allows less heat in general so that you don’t move it into the crowns. That’s the kind of fire that ponderosa pine historically had, and the kind of fire we want as homeowners with our houses next to the ponderosa pine forest.
Tell me about some of the challenges that land managers face in terms of getting more fire on the ground. What are the barriers to doing this more often?
One is what we talked about a little before, is that these windows to be able to burn—prescribed fires are not something that managers decide they’re going to do and then they just go take some drip torches out and throw some fire on the ground. There’s a large planning process that goes with this, actually for many years ahead of burns. That planning process defines: what are the relative humidities, what are the winds, based on the fuels of the site, when is an appropriate time to burn? We call those the burn windows. Those burn windows are hard to hit sometimes, depending on what’s going on with our weather. That’s one barrier, definitely, is being able to have windows.
The other is smoke. The fire managers live in our communities too, they suck the smoke from prescribed fires as well. No one really enjoys sucking smoke. It’s not good for us, and everyone knows that. But at the same time, it’s comes down to how do you take your smoke? Do you want it in a big wildland fire where it’s much heavier and much more uncontrolled? Or do you want it in small bursts?
Managers are always trying to juggle really important events going on in town, other things, tourism, all of that, with being able to have these windows where they can actually put fire on the ground in a reasonable manner.
What’s the main thing that you want folks who live in northern Arizona to know about prescribed fire?
That it’s really important, that it’s hard to do, that it’s planned and planned well—and well in advance. These aren’t things that happen willy-nilly, they really something that are important to our systems, that managers spend a lot of time planning for and getting ready for. I think having some support for getting these things on the ground—smoke is never fun, it’s always going to be inconvenient to somebody at some point or to some kind of event, but wildfire is far more inconvenient to our lives, a wildfire in a bad way.
Andi Thode, thank you so much for speaking with me.
Thanks for having me.
See maps of current wildfires or prescribed burns at Inciweb and the Southwest Coordination Center.
