Researchers at OSU take measurements of plants in sagebrush habitat being encroached on by western juniper.
SageSTEP
An arid and fragile landscape dotted with sagebrush and perennial grasses stretches from the eastern slopes of the Cascades to beyond the Rocky Mountains and into parts of Canada. More than half of this sagebrush steppe ecosystem has been lost, threatened by climate change, invasive plants and human activity. A scientist at Oregon State University has spent more than a decade leading a team working to protect sagebrush habitats from another growing threat: huge wildfires. Lisa Ellsworth, a range ecologist and assistant professor at Oregon State University’s College of Agricultural Sciences, joins us to talk about her new research and how it’s helping inform wildfire management efforts in sagebrush habitats in Oregon, Idaho and Washington.
Note: The following transcript was created by a computer and edited by a volunteer.
Dave Miller: From the Gert Boyle studio at OPB, this is Think Out Loud, I’m Dave Miller. For the last 10 years, researchers at Oregon State University have been studying various ways to reduce the intensity of destructive wildfires in the arid west, the fragile and immense sagebrush landscape that stretches from east of the Cascades, past the Rockies, and up into Canada. Now, those researchers have more information about the best ways to balance wildfire risks and the dangers from invasive species all in our warming world. Lisa Ellsworth is a range ecologist and assistant professor at Oregon State University’s College of Agricultural Sciences. She joins us to talk about her new research, which was published in the journal Ecosphere. Lisa Ellsworth, welcome.
Lisa Ellsworth: Thanks Dave, thanks for having me.
Miller: Thanks for joining us. What were fires like historically in these lands?
Ellsworth: So historically, there was fire in the sagebrush ecosystem. It would have been much patchier than what we see today. We hear about fires on the news that are 100,000, 200,000, 400,000 acres. And we would have had some large fires historically. But the inside of the fire perimeter might have been more patchy. Some more plants would have survived those fires.
Miller: And how much did those grasses or plants evolve with that kind of fire?
Ellsworth: They evolved with fire, but less frequent fire than what we see today. Some folks have given estimates that we might have had fire around every 50 to 100 years in some of these systems. So plants are evolved to fire on that temporal scale, not on the scale of burning every couple of years like we’re starting to see now.
Miller: Every couple of years we’re seeing fires. Can you give us a sense for the scale of them now, and the intensity of them now?
Ellsworth: If you listen to the news in the summertime, it’s quite common to hear about fires that are tens if not hundreds of thousands of acres. Some of the recent big ones in Oregon have been the 2012 Long Draw Fire, which was over 500,000 acres. The 2014 Buzzard Complex was over 400,000 acres. Last year we heard a whole lot about the Bootleg Fire, which was over 400,000 acres. That was the number one priority fire in the nation for a while. We call fires that are larger than 100,000 acres megafires. So we’re seeing more and more of these megafires, and we’re not having as many of the lower intensity, more beneficial wildfires.
Miller: What’s left behind from a grassland fire? So often, we can be inexact and talk about wildfires, and conflate forest fires with grassland fires, or sagebrush steppe land fires. So what is it like after a big contemporary fire passes through?
Ellsworth: That’s a really good question. It’s variable. There’s a lot of black. It can be intimidating, I won’t understate that, because even the native grasses will be top-killed, we call it, by the fire. So the top part burns off. But the live growth tissues below the ground might still be alive. So it looks quite harsh in the beginning.
Ideally, we would have some patches of unburned plants, we call those islands, where there’s a few shrubs and a few grasses remaining, and those are going to provide the seed source for re-colonizing the burned areas. With invasive grasses that we’re getting in these systems now, there’s less patchyness to our fires, because those invasive grasses provide a really continuous fuel source. So we’re starting not to see as many of those unburned beneficial pockets for re-colonizing the post-fire environment.
Miller: What are the invasive grasses that are the biggest problems?
Ellsworth: So cheatgrass is the big one. That one is problematic all over the Intermountain West, and beyond. We also are seeing a new one called ventanata, as well as Medusa head. And they all behave fairly similarly. They’re all annual plants. So they just grow one year, they’re fairly short in stature, but they put out a ton of seeds. So they do really, really well in those post disturbance environments.
Miller: They do better post fire than native grasses do.
Ellsworth: They can do really well, just because they put out a ton of seeds. So there’s a seed source out there for them to become established after the fire.
Miller: So what were the goals of the research that you and other members of the team have been doing for the last 10 years?
Ellsworth: This is a project that’s called SageSTEP. That stands for Sagebrush Steppe Treatment Evaluation Program. And what we’ve been looking at are ways to do fuel treatments, and by fuel, I mean all of the burnable plant material that’s out there, and by treatments, I mean ways to redistribute or reduce that fuel.
So some of the things that we’ve tried, in sites all across the Intermountain West, are prescribed burning, intentionally putting fire out there under less severe conditions so we can get the kind of fire that we want. We tried mechanical treatments, which means taking a tractor out there and literally mowing the sagebrush down to about half of its height. We tried a couple of herbicide treatments that didn’t work super well.
The goal of these treatments is to either reduce or redistribute the fuel so that it’s closer to the ground. So when fire comes through, the flames aren’t as high. Flame length is a measure of fire intensity.
Miller: So even, for example, if you mow, and you leave behind some chopped up bits of sagebrush, that’s not as big a problem as letting those plants get taller?
Ellsworth: If they’re taller, you’re going to have higher flames. And if you have over about 4ft flame lengths, you can’t get suppression crews in there. So in order to make the future fire that’s always coming one that can be fought by suppression resources, we want to keep those flame lengths lower.
Miller: What was the problem with herbicides?
Ellsworth: That’s a good question. Part of the original goals of the project were to restore the understory grasses. And using herbicide to kill some of the shrub canopy did do that. However, from a fuels perspective and a fire risk perspective, a bunch of dead sagebrush standing out there is kind of worse than a bunch of live ones, in terms of stuff that’s going to burn. So the herbicide treatment that we tried is not something that I would recommend from a fire risk perspective.
Miller: So correct me if I’m wrong. but one of the big findings of this is that mechanical thinning and controlled burns were both pretty effective in lowering severe wildfire risk going forward. But the controlled burns were more likely to lead to more invasive species in the future. Is that right?
Ellsworth: Possibly. The study that just came out looked at the fire behavior. It’s correct that the prescribed fire gave us the longest term risk reduction in terms of more desirable fire behavior in a wildfire. However, we do know that, as we just talked about, invasive species do really well after disturbance. So there’s some trade off to consider with introducing some risk now with these fuel treatments, to possibly prevent a larger risk later.
Miller: Can you give us a sense for the sheer size of the landscape that we’re talking about here?
Ellsworth: The sagebrush steppe is huge. I’m sitting here in Oregon, but if I drive up and over the mountains and come down to about Bend, we start to hit sagebrush. That sagebrush will continue all the way across the state, all the way over to the Rocky Mountains, and some even beyond the Rocky Mountains, into the Colorado Plateau, and even into the western part of the Plains States. So this is a giant ecosystem.
Miller: How does that complicate what we’re talking about if one of the potentially most useful interventions are people on tractors? You’re talking about an unimaginably vast landscape.
Ellsworth: Well, it’s divided up into treatment units. And the Bureau of Land Management is the largest public lands manager and steward in these areas. They’re actually currently implementing what’s called the Tri-state Fuel Break Project, where they’re working across Oregon, Nevada, and Idaho to put in 435 miles of mostly mowed fuel breaks. So there are management partners on the ground that are very actively working on this. BLM is one of our very close partners in research and management in doing this work.
Miller: What role does cattle grazing play in terms of the two twin issues we’re talking about here: invasive species, plants like cheatgrass or medusa head or others becoming more plentiful, and the risk of serious wildfires? How does grazing affect those?
Ellsworth: Grazing is a lot of different things. Around the late 1800s, early 1900s, a lot of the sagebrush steppe was very severely over-grazed. So there’s this legacy of degradation that predates the situation that we have out here right now. Animals were much more intensively using rangelands than what they are today. So I want to temporally separate a little bit of what the grazing impacts are. We still use these areas as grazing lands, and not all grazing is created equal. The timing of grazing matters. The type of animals matters, the seasonality, the frequency. So grazing is something that can be very destructive to sagebrush ecosystems.
It’s also a tool to remove some of the fuel in advance of these wildfires in some places. For example, places that are already completely hammered with invasive grasses, folks will go in and use animals to reduce some of that invasive grass fuel load.
Miller: Before we say goodbye, on your twitter bio, you call yourself a “pyroecofeminist”. What does that word mean?
Ellsworth: The “pryoeco” is a recognition of the fact that our plant and animal communities and our ecological processes, like fire, are inextricably linked. I think we hear a lot about “fire is bad.” But these plant communities and these wildlife species evolved with fire and need fire in a lot of cases.
The feminist part, my career started as a wildland firefighter, and I was usually the only woman in the room, and the only woman on the crew. And so, one of my personal and professional goals is to broaden participation for people who identify as women and other underrepresented groups in the fire sciences. So for example, yesterday I took my lab of seven women and they all got fire fire certified. We’re all sore from doing the pack test today.
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