Arizona researchers are mapping out invasive grasses to figure out where wildfires might strike

Invasive grasses like buffelgrass and stinknet have grown across large swaths of our Sonoran Desert, and they’re fueling wildfires — literally adding fuel to the fire.

Now, researchers from all three Arizona state universities are working together to figure out where those invasive grasses are, map them out and evaluate different approaches to manage them.

It’s being done in partnership with the Arizona Department of Forestry and Fire Management funded by a Regents’ Grant from the Arizona Board of Regents.

The Show spoke with two of the researchers more about it: Andi Thode, a professor of fire ecology and management in the School of Forestry at Northern Arizona University and Fabio Albuquerque, associate professor at the School of Applied Sciences and Arts at Arizona State University.

Full conversation

ANDI THODE: With the Sonoran Desert being the most biodiverse desert in the world, we also have a large diversity of invasive species that are causing problems, and they include grasses and forbs. So things like red brome, buffelgrass, fountain grass, stinknet and some Schismus species, which people sometimes call Mediterranean grass, are some of the bigger players in driving fire in these ecosystems.

And the big issue with these is that our desert is really patchy, and these species have come in and filled in those open patches between the native vegetation, and that allows fire to carry through the deserts when fire didn’t before, and it’s something we call the grass-fire cycle.

LAUREN GILGER: Have we seen wildfires in the state that are really fueled by these kind of invasive grasses?

ANDI THODE: Yes, we’ve had some very distinct years for that, and those fires have gotten — some of them have gotten over 100,000 acres.

LAUREN GILGER: So when we talk about sort of the patchiness of the desert, I think what’s striking to me about what you just said there is that we don’t think of the desert as a place that’s really prone to wildfire. But are those species what’s changing that narrative?

ANDI THODE: Yes, absolutely. With those open patches, there wasn’t a lot of vegetation between our large palo verdes and mesquite trees and our saguaros. There was some shrubs here and there, but there was open ground, and that open ground is now filled with invasives, and that’s the problem. In certain years, it’s not every year, but it really is moisture dependent.

LAUREN GILGER: So this project is funded from a grant from the Arizona Board of Regents. It’s taking professors from all three state universities, and you two are representing two of them here.

But the idea, it sounds like, is to get a better handle on where it is that these kind of invasive species are so that fire managers can be better prepared. Tell us, how do you approach something like this?

FABIO ALBUQUERQUE: Yes, so first thing to know is we need to fill gaps of knowledge. So a bigger problem, like Andi said, the invasive grasses, they can change the landscape, they can make more wildfires, they can make them more frequent, destructive.

But what we don’t really know is where they are, right? And we do not really understand deeply their cycle in the desert. So we want to get that information first, so we can generate some information for managers, we can create some kind of risk maps where managers can visualize where these areas could be located over the space and maybe over the time, too.

LAUREN GILGER: Right, so if you don’t know where these non-native grasses have taken over, it’s difficult to predict where a wildfire might erupt.

FABIO ALBUQUERQUE: Correct. So knowing where these species are is the first step towards understanding the process.

LAUREN GILGER: OK, so give us the logistics here. How do you go about mapping something like this? Is this like you have to physically fly over the place, drive out there?

FABIO ALBUQUERQUE: That’s a very good question. So we don’t have a lot of information, a lot of data on the field information. So we use some kind of modeling that would allow us to relate the basic information we have — so we don’t have a lot of information, right, where these species are located — we relate these locations with the environment that these species live in, and then we predict over the space. So we basically use modeling to predict where these species are over the space.

LAUREN GILGER: So, Andi, you’re on the forestry, fire management side of this. How would you like this data to be used by fire officials, right? Like you’re talking about support tools, like actual maps of this. Is this something you imagine them being able to look at in terms of how they’re treating these grasses, trying to get rid of them before wildfire season hits?

ANDI THODE: Yes, our project actually takes it a little further than this. We’re really going to be putting in some experiments on the ground to look at what sort of treatments people can do that would be most effective.

That’ll be done in two different ways. One way will be looking at treatments that they’re already putting in and monitoring what they’re doing. And then another way will be putting in actual experimental blocks where we might try some new, novel treatments in areas across the desert.

LAUREN GILGER: What does that look like? What is the traditional approach to managing this versus some novel ideas?

ANDI THODE: Well, traditional approaches vary from hand pulling, mechanical pulling, to herbicide use. Some people have tried using fire. With the species that we have in the desert, that doesn’t always play well, but we’re looking at some alternatives to that, which is propane burning, which is a very targeted burning of just the invasives with very little damage to the natives, which is a completely different idea than using prescribed fire.

So there’s a lot of different ways. Some people are even thinking about grazing with sheep and goats as a potential. And with all of these treatments, there’s pros and cons to them, and so the balance is finding what treatment can affect the non-native and invasive species the most while helping to do the least damage to the desert natives, which is actually a tricky thing to do.

LAUREN GILGER: Right, so you’re talking about burning the grasses that surround saguaros, which we want to keep, and not damaging the saguaros. Is that possible?

ANDI THODE: With this propane burning treatment, that is possible. There’s also people are looking at pruning some parts of the desert as well. You know, there’s a lot of different treatments that managers are doing out there, and in some places, they’re pulling from treatments that have been done in forest ecosystems and bringing those down to the desert. Those are really thought, many of them, to be inappropriate and actually doing some damage to the desert, but managers are also struggling to know what to do.

So that’s the hope is that we can help move things forward in a sense where we have some data, we have some information, and we have a range of effectiveness and a range of knowledge on these and create sort of a menu of treatments.

FABIO ALBUQUERQUE: If they know where they are, if they know where higher risk is, they can target, they can monitor, they can do fire prevention, they can protect the habitat, so there are so many things that they can do that this mapping can help them to take these better decisions.

LAUREN GILGER: All right, well, lots to watch for in terms of how this comes about. That is Fabio Albuquerque, an associate professor at the School of Applied Sciences and Arts at ASU; Andi Thode, professor of fire ecology and management in the School of Forestry at NAU, principal investigator for this three-year project that’s just getting started.

Fabio, Andi, thank you so much for coming on. Thanks for explaining this. Good luck with it.

ANDI THODE: Thank you so much, appreciate it.

FABIO ALBUQUERQUE: Thank you so much for the invitation. I appreciate it as well.