AoR 5: Kirk Davies, Invasive Annual Grass Management

Dr. Kirk Davies, lead range scientist at the Eastern Oregon Agricultural Research Center (EOARC) in Burns discusses with Tip invasive annual grass (IAG) on western rangelands and current research into promising new approaches to biological control of cheatgrass and ventenata. The conversation weaves in the role of fire in semi-arid shrub-steppe ecosystems, challenges in rehabilitating annual grass-infested rangeland, grazing as a biological control for cheatgrass, the pros and cons of sagebrush plants as refugia, and Dr. Davies' thoughts on how to promote perennial grasses simultaneous with grazing IAG. 


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>> Welcome to "The Art of Range," a podcast focused on rangelands and the people who manage them. I'm your host, Tip Hudson, range and livestock specialist with Washington State University extension. The goal of this podcast is education and conservation through conversation. Find us online at

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Welcome to "The Art of Range." My guest today on the show is Dr. Kirk Davies at the Eastern Oregon Agricultural Experiment Station in Burns. Kirk, welcome to the show.

>> Thank you, and for having me.

>> What was your pathway to becoming a range scientist, and how did you end up in Burns, Oregon?

>> Well, that's kind of interesting. So I was always really interested in being outdoors and stuff like that. So when I was getting close to graduating from high school, I thought, you know, this range field sounds really interesting. And so, I went into that, and my original plan was just to go get a four-year degree, and go out and work in the field. And I actually came to the Burns Research Station as a summer student to work for one of the other scientists here, and I started doing that. I thought, man, you know, I'm not sure I want to quit going to school. I think I might want to actually be, you know, a scientist, and get, you know, an advanced degree -- you know, a Ph.D. And so, that's kind of how I got into that. And then, of course, I end up working with one of the scientists here for my Ph.D. in Burns, and so that was kind of how I got looped in with the Burns Research Station, in terms of potentially being a scientist. And I didn't really think I'd end up in Burns, because it's a very small research unit. And so I was starting to get close to being done, and I started applying for jobs in other areas, most of them being -- you know, I'd be a professor at a university. Dr. Roger Sheely [assumed spelling] had a post-doc open, and it was like a pretty good opportunity to work with a pretty well-known scientist, but then also, at that time, I met my future wife, and she had a job here. And so she kind of was, you know, wanting to, you know, stay here for that. And so, I asked, you know, if they were -- if I would be qualified for it, and he said, "Yeah, please apply." So I took that job, and nine months into that job, they had a scientist position open here, a permanent scientist position. And so, I applied for that, and got that, and then I've been here ever since.

>> Mm-hmm, and you're the lead range scientist here?

>> I am now, yeah.

>> How many folks are here?

>> So there is -- I think we have eight scientist positions on the federal side, and we have then three on the OSU side. And right now, we're kind of in a -- we're filling a bunch of positions that have been open for a while, in terms of scientist positions.

>> In a 2012 rangeland ecology management paper that you coauthored with about a dozen others -- a big paper, titled "Revolutionary Land Use Change in the 21st Century, Is Rangeland Science Relevant?" You wrote -- or you all wrote, "The revolutionary land use changes necessary to support national and global food security while maintaining other ecosystem services make rangeland science more relevant to sustainable land management and policy now than ever." I would say this is mostly why I got into the range field, before I had enough life experience to really think much about it. Namely, what interested me was that it seemed like an integrative discipline that set out to make real-world decisions in real time, that make a difference to real people -- decisions based on a broad view of all of the resource values, and the social aspects that are relevant to a given decision. But it seems like there are fewer universities doing range research and producing range-educated graduates than when I left the University of Idaho back in 2001. Do you think that the -- that downward trend is played out, and might reverse? It feels like there's jobs out there for people who have that kind of background, even if they're not advertised specifically as rangeland jobs.

>> I'm hoping it's reversing. I haven't seen it reverse yet. As you said, I mean, the jobs are -- there are a lot of jobs out there, and some are specifically range jobs. But the number of students coming out with a range degree is really low, and for me, personally, I'm not as tied to the university as other people are. I mean, I have grad students at the university, but I'm not there seeing how many students they have come through. But what I do notice is, like, when we look to hire post-docs or full scientists, that there just isn't the number of ones that have a range degree as we would've saw, you know, 10, 15 years ago. And so, it's -- I think it's a concerning issue that hopefully will reverse itself as people realize that there's, you know, plenty of very rewarding jobs that are, you know, fairly high-paying, too.

>> Mm-hmm. In the podcast, we're doing a series of episodes on livestock management for ecological resiliency, whether ecological, economic, or social, and all three of those are important for rangeland health. That follows an episode series on some fundamentals of rangeland management, at least with regards to livestock. A lot of ranchers find themselves today on range that is infested with invasive annual grasses. That could be cheatgrass, ventenata, medusahead -- we have all those in Washington and Oregon, both, and in much of the west. There's a lot of talk about using grazing to control those grasses, but it seems like making progress -- and by progress, I mean decreasing either the extent or the density of invasive annual grass -- has been limited. And those successes seem to be relatively local, rather than regional. What have you learned here at the Burns Experiment Station about grazing to suppress invasive annual grasses?

>> We haven't done a lot of it, but what we have seen of it, it's generally been not very effective. Maybe you can suppress in the short-term, but it's really hard to make that transition then to a perennial-dominated community. The -- we've been axillary associated with some of the research looking at now fall and winter grazing of annual grass-invaded areas to reverse that trend, but most of that is still pretty preliminary. Most of it hasn't had a control, versus that kind of treatment, but it looks promising. The question is, is -- in these communities, is there enough residual perennial to take advantage of any reduction in annuals? We also see that some of these areas don't really have the fall green-up of cheatgrass, or they don't have it every year. So that makes it challenging to have as an effective treatment as we would like. On the other end of it, the spring treatments to graze it generally haven't been very effective at, you know, transitioning to a different plant community, and large because it's really hard to graze the annuals when the perennials are also green and susceptible to, you know, pressure from grazing. What people have had success with that have been really on top of it, and have been, you know, very carefully monitoring. As soon as, you know, you have green-up of your native perennials, then the cows have to go somewhere else. So it's very challenging, but there is -- it looks like there's a future for more research in that, and then, hopefully, you know, some more ability of people to apply that.

>> Yeah, it seems like a lot of the writing on grazing to discourage cheatgrass have focused on targeted grazing in the spring, when the seed heads are green, and we can attempt to stop seed production, or slow it down. But Keepen Gwen [assumed spelling], who was the NRCS state range specialist for Washington State for some time, liked to say that the first rule of grazing management is that the cows have to be somewhere [laughter]. The second rule is that they can't be everywhere. And if you've got a large area in which you're trying to treat cheatgrass with cattle, and it requires annual treatment, you can't have all your cows be on every acre, which means every acre that they're not on, you've got cheatgrass growing unmolested during that period of time. Talk a bit about grazing to encourage the vigor and reproduction of perennials. You know, severe grazing, or Ken Tate [assumed spelling] calls improper grazing, results in too much pressure on perennial grasses. And that causes the plant community to shift toward plants that either tolerate heavy grazing -- you know, whether that's frequent defoliation or less frequent but severe defoliation, or maybe both together. That decline in perennial grasses is often accompanied by a complementary or corresponding increase in invasive annual grass. So heavy grazing to reduce fire risk could backfire, and increase fire risk by increasing the invasive annual grasses. I think we're at a point in this discussion, this, you know, west-wide discussion about how to manage wildfire. People are paying attention, and I'm afraid that we're going to end up with, you know, some polarized viewpoints, where you have some of the industry saying, "You know, graze it all, graze it hard. That'll slow down wildfire," and others saying, "Graze it all, graze it hard is what got us here in the first place, because these rangelands were not all covered in cheatgrass previously." What are your thoughts on grazing to encourage perennials?

>> I think that it's really challenging to encourage perennials, you know, grass and stuff, with grazing. I think the more effective way of viewing grazing with most of our native perennial grasses is grazing to not damage them, or to essentially make them respond differently to fire. The actual grazing to encourage them to grow better or more than that -- there hasn't really been any true evidence that that works. I think, as you kind of mentioned, the fire aspect -- there is an aspect with grazing to manage fire that's going to be helpful to reduce the likelihood of losing them in fires, or even having a fire. But as you know, there's a real challenge with balancing that with not encouraging annuals. And that's where I think that, you know, we've seen a kind of -- a new pressure to, or a new desire to start grazing outside the normal grazing period, and start grazing in the fall and winter where we can be mainly just removing fuels, versus actually going in and removing photosynthetic active tissues. And that's, I think, where we're hopefully to have some effect on fires, is there more -- more growing season use largely would be a risk of having, you know, some detrimental effects to grazing, which then potentially would open the plant community up to more exotic annual grass invasion. On the other end, if it's already annual grass-invaded, the management of the fuels then is a higher priority. I mean, they're -- they've lost the perennials already. We just need to manage the fuels, and fall, and spring, and summer grazing would all be methods to reduce that likelihood of a fire in the annual grassland.

>> Mm-hmm, that seemed to be the thrust of the paper in rangelands with Barry Perryman [assumed spelling] and a couple others from Idaho and Nevada. You might've been on that paper. It was looking at the possibility, you know, based on some of their observations with ranchers, that that fall and winter grazing seems to disrupt the litter in a way that is a key component of trying to stop cheatgrass. You know, they argued that we've focused on having the primary impetus in a grazing plan -- the perennials, and that in places where we have a lot of annuals, we may have to shift the primary focus on, you know, some way to interrupt the reproductive cycle of those annual grasses. And because most of the targeted grazing efforts have been on seed production rather than some other biological mechanism, it seems like we've missed that. A recent case study that I've worked on with the Richards Ranch in the Owyhees in Idaho looked at some of the Richards' observations, that cows grazing on cheatgrass range in the late fall -- and this is quite a bit lower elevation than we are here. But those cows, Tony says, were pawing through the litter to get at cheatgrass tillers that were actively growing inside that litter layer after everything else had gone dormant. And in the process, they were breaking up the litter cover, you know, consuming some of these fall-germinated live plants, and then potentially exposing soil micro-sites underneath the litter, or by opening up the litter, that might then accept a perennial grass seed. What's your reaction to the possibility of using dormant-season grazing to control cheatgrass? You've discussed that a bit, but is there any -- what research is there now on that that's either been completed, or is ongoing here at the station?

>> There's just a little bit, and it's more to do with medusahead, but it's the same mechanism. We actually see them consume the litter as well as the green medusahead coming up, and really, there hasn't been a lot done with it. And the problem is that, you know, these things need to be done at a fairly large scale, and what research has been done to date has all been kind of before and after. Which is good research, but to really get at the mechanisms, there needs to be more research where -- that have the controls, where it's not being fall-grazed, compared to where it is. But definitely fall and winter grazing is a very effective way to reduce annual grass litter, and probably reduce annual grass production the next year. And what we see with that is that it is probably an opportunity to help make control more effective, and maybe even re-vegetate these communities. Those next steps are what need to be researched, and what we've seen with, like, medusahead, which I'm pretty sure applies with all annual grasses, is that part of the challenge with good control sometimes is -- with herbicides is removing that litter some way to get the herbicide on the ground, versus tied up in the litter. The other thing with removing litter is that it also -- all these annual grasses germinate better with that litter cover, and they have a harder time germinating and establishing -- it's more than just germination -- on areas that are just bare ground. It's a more harsh micro-site for them, that they're not as adapted to as, you know, growing with that litter layer over the top of them.

>> Mm-hmm, now we've been saying for a long time that some litter is good, because especially in a landscape where you have natural interspaces between plants, because there's just not enough precipitation to support 100% ground cover like you would in a -- you know, a more [inaudible] solid-forming natural plant community. It's important to have some litter to protect bare soil. How much litter is enough, and how much is too much in a way that promotes the invasives?

>> Yeah, I think the challenge there is that it's all going to be site-dependent, and it's -- as we get steeper slopes, as you move more litter, especially if it's an annual grassland. We would want that litter, then. It's where the erosional forces are the -- more of the soil's surface is exposed to erosional processes. In the plant communities that are dominated by perennials, and native perennials especially, what research I've seen and stuff that I've participated in is that the actual ground litter doesn't really change with grazing in those communities. Now, if you go into an annual-dominated plant community -- sorry, I should specify. With moderate -- you know, 40% forage utilization, it doesn't change the amount of ground litter. As it goes into an annual grassland, of course, most of that stuff that's this year's crop is -- will be next year's litter, and then if the litter is consumed, then they can vastly change that litter. And I don't know how we get out what's an optimal amount of litter remaining in those communities, because every site's going to be different, and every year's going to be different. If we have, you know, a very heavy rainfall year, or snow year with lots of runoff when it melts, we're going to need more litter out there to help slow down the erosional forces. At the same time, in the long run, it would be better if we did get that litter down and perennials established in there, because over the long run, a perennial-dominated community is going to be much, much less likely to have soil erosion and other degradation of the soil resource. So it's always -- it's kind of always a question that's going to be up in the air. I think if we can establish that this is a method to get to an endpoint that's desirable, a short-term severe reduction in the litter of annual grasses is probably well worth it.

>> Mm-hmm. You guys have also done some research on various management combinations to try to reduce fire risk, and invasive annual grass control is really related to the broader issue of managing grazing to limit wildfire. And we'll kind of shift to that. You know, research indicates that we can reduce fine fuel loads in a way that limits the extent and the severity of wildfire. Probably the goal is not to eliminate wildfire, because these plant communities are fire-adapted, and many would say disturbance-driven. Agree or disagree, and what kind of management combinations have you guys looked at that may be more effective than grazing or herbicides singly?

>> I think there's -- within the first part of the question, I think we probably go from fire-tolerant originally to then -- in the lower elevations, to probably fire-adapted in the higher elevations -- communities. In the lower elevations, as we continue to have more cheatgrass invasion, they're probably becoming essentially not-adapted, or in-adapted to fire, especially as they lose the perennial bunchgrass component. Then fire becomes a huge shift in the plant community to a state that we won't recover back from without enormous inputs. But I don't think, you know, on the other end of it, that we can have, say, mountain big sagebrush communities, without fire to essentially control conifer encroachment of them. We've seen, you know, huge expanses of, you know, junipers, and pinea pine, and stuff into mountain big sagebrush communities, and if we don't have that periodic fire, we'll lose those communities. And what was the second part of the question?

>> Yeah, what research have you done looking at combinations of, say, prescribed fire plus herbicide, or prescribed fire plus grazing, or grazing plus herbicide, as a means of controlling things like cheatgrass and medusahead?

>> We kind of did, you know, kind of combinations of all of them. The most effective one, if you've got a fully-invaded site, you know, very few residual perennial bunchgrasses, is we've found that a good prescribed burn to remove the litter and potentially remove anything that's already germinated, say if it's early fall. And then spraying a pre-emergent herbicide, then waiting a year, and coming back, and seeding into them. Grazing by itself we've found generally wasn't too successful, and same with prescribed burning. But you -- especially if you combine, you know, one of those with a herbicide treatment to then control the next cohort of annuals that are going to try to come up kind of creates a window in there that we can potentially seed perennial vegetation into.

>> There's some discussion about livestock grazing being an ecological substitute for fire as a disturbance. Any thoughts on that?

>> I think in some systems, it could be. I think it's a little harder in the sagebrush communities. The one kind of scenario that you could see it being a substitute for fire potentially is just reducing the fine fuels, and keeping those turning over at a faster rate. But by and large, fire in this system affected the woodies more than the herbaceous, and at least grazing with cattle isn't generally affecting the woodies. They're generally avoiding them, or consuming very, very minute amounts of them. So in that case, no, grazing really wouldn't be a substitute for fire. But what we have seen, I think, that's kind of, you know, what some of that alludes to, is that we can manage the fine fuels with it, to the point that the fires are less severe. And that's important now because of the fact that when we have a severe fire, then annual grasses are a threat, versus historically there wasn't an annual that would then take over the plant community and shift the trajectory to something that we would have a hard time coming back from.

>> Mm-hmm. There's some evidence that limiting sagebrush canopy cover below some threshold percentage may be critical in preventing a fire of severity that results in a standard-placing fire, potentially replacing both the shrubs and the bunchgrasses if there's sufficient heat to kill the crown of the bunchgrasses. Any research on that here? Any thoughts about methods for sagebrush canopy reduction?

>> Yeah, that's a challenging one, but there's pretty strong mechanistic research. And I was involved with this at CHATA [assumed spelling]. Boyd [assumed spelling] was actually the lead on it, but it showed that, in the Wyoming big sagebrush communities, that almost all the mortality of bunchgrasses occurred within, like, 50 centimeters of that basal -- the trunk, essentially, of the sagebrush plant. As you got between the sagebrushes, those plants generally survived the fire. As we get more and more sagebrush, and it thickens up in there, then that distance between the sagebrush is so small that you have a huge amount of the area essentially suffering high mortality. The challenge in those communities -- and we've looked at some of this -- is that, you know, mechanical treatments or herbicide treatments to reduce the shrubs would be, you know, essentially the only -- well, not the only way, but the most easy-to-apply method to change then the level of sagebrush cover. What we've seen, though, is that once you have really high sagebrush cover, then the risk with treating that sagebrush is then that opens the plant community up to annual grasses, just by this disturbance of reducing that dominant vegetation. Probably -- there's probably some method of using maybe a browser, such as sheep, at the right time that could maybe reduce them, and slowly over time, so that the perennial bunchgrasses could respond favorably. I would say our probably better bet is to try to limit that from happening in the first place, and from a lot of our long-term sagebrush stuff, we see that if we manage these -- Wyoming big sagebrush, especially -- fairly well, that they don't really thicken up to the point that they're going to have that high risk. Now, on the higher end, where there's more moisture, they're going to get really thick with sagebrush, because there's just more resources available. However, those plant communities -- they're more resilient, and I think a lot of those will recover naturally after a fire in them. But probably more important in those to keep it from getting overly thick is to keep that infrequent fire occurring, which we haven't done so far. Which, you know, you thicken up with sagebrush, and then you have that transition, then, if it's available, a conifer encroaching there. And then you have an even more severe fire, because when a juniper burns, you have a very hot, you know -- you know, essentially, bare spot after the fire where that juniper was, because of all that dry, woody vegetation releasing so much heat energy into the soil.

>> With fire on sagebrush, and the mortality on perennial grasses near the sagebrush, is that because it's hotter right there, or because the residence time of the heat is longer?

>> It's a combination of both. We did some research where we actually had thermocouples underneath the sagebrush in the interspaces, and it was that combination that -- with that woody vegetation, it was much hotter, but it was also then, you know, much longer period of time that you had these elevated temperatures. And what research is out there is pretty strong that that combination of elevated temperatures and elongated elevated temperatures is where you see your high mortality of your perennial bunchgrasses, as well as, you know, others, like perennial forbs.

>> Yeah. And you say managing sagebrush well so that it doesn't expand too much -- does that primarily include protecting perennial grasses so that they're providing some pushback and competing below the ground with the sagebrush?

>> Yes. When I said managing sagebrush, I meant actually more manage the sagebrush community, and that's having a good grazing system that's allowing those perennial bunchgrasses to maintain their size and their density across the landscape.

>> I've seen a number of estimates on what the historic fire return interval was on different kinds of sagebrush plant communities, and there's -- you know, those numbers range from 35 to 200 years, depending on what kind of sagebrush it is and, you know, potentially other factors, like fine fuel loads in the sagebrush ecosystems. What's your guess as to how often, you know, these shrub steppe plant communities in central Washington, that are characteristic of quite a bit of Washington as well, and other parts of the intermountain west and the great basin -- what do you think we could expect, in terms of a fire return interval that we could -- should consider natural?

>> I think the prior estimates you quoted are probably pretty accurate. As we go from low elevation to high elevation, more productive to less -- or vice versa, that it's just so variable, and we see areas -- of course, there is some exceptions. There are areas that maybe didn't have a lot of potential for a naturally-occurring fire, but then there's a lot of fires that were lit by Native Americans. And I think that that wide range is probably just what it is, that -- I don't think there's one standard, you know, fire return interval that would apply for all. As we get the higher elevations -- you know, Rhett Miller [assumed spelling] has some areas that he's documented fire return intervals, you know, as short, I think, as, like, maybe 12 to 14 years. And then of course -- then there'll be a period that there's, you know, 44 years without a fire, and then they'll have two back-to-back. And you come down these Wyoming big sagebrush communities, especially some of these at really low productivity -- it would be very hard to carry a fire in there at all. And so, it must've been, you know, a heck of a, you know, weather event, you know, high winds and stuff like that, to carry these fires. So, sadly, I don't think there's one or even very -- you know, there's no good estimate for it all, because it's so variable across the landscape, and across the region.

>> In sagebrush plant communities, what do we lose if we prevent it from burning periodically? Is it mostly -- you mentioned that sagebrush canopy dominance is likely, you know, somewhat limited internal to the plant community, and not just by fire. Are there other things that we lose if it doesn't burn sometimes?

>> Yeah, I think the -- especially the higher elevation. That's where our -- our most obvious effects of not having fire, and what we see there is that, you know, over time, that the conifers generally will encroach. And you will lose the sagebrush community, which then means it's not habitat for anything that needs sagebrush, like sage grouse. We've also looked at even just burning within those, and you do -- with fires, you create a different habitat out there that maybe has more insects, or different types of insects, more flowering forbs, or different flowering forbs, different shrubs for a short period of time. And then, you know, it goes back to sagebrush in throughout there. When we don't have any fire across the landscape, then you essentially lose those different types of habitat, and that probably affects productivity, in terms of different wildlife species. The lower elevation sites -- it's challenging, because at this point in time, there's such a risk of annual grasses coming in after any kind of disturbance that, you know, removes a dominant vegetation, whether it's perennial bunchgrasses or shrubs. And so, at this point, I don't know what we lose versus -- by not having fire, compared to what we'd lose if we had fire. I think they're starting to, you know, balance each other out, or even, you know, be more negative to have it burn, and have annual grass come in. Now, that being said, we do see that some of these plant communities -- big sagebrush plant communities that are in really good condition, if they burn, they don't have that cheatgrass invasion, or medusahead, or ventenata, that they're dominated by perennial bunchgrasses. You maybe don't have shrubs for a long time, but you have a nice native grassland, that at some point, so long as it doesn't, you know, continue to burn too frequently, will then be re-dominated by shrubs. But I think at the lower elevations, that we don't really have a problem with that because of the increased fuel loads with annual grass, stuff like that -- that we've seen most of those areas be -- you know, burn too frequently, or be at risk of burning. That those -- which probably isn't a big issue to not have fire in them, compared to the higher elevations where we need fire to limit conifer encroachment.

>> There's been quite a bit written about how rangelands are characterized more by variability than by aridity, and that if that's the case, that maybe abiotic factors or episodic biological events may drive plant community change more than grazing management. Your thoughts on that? What's the variability around here? I've seen some charts that show, you know, coefficient of inter annual variability in precipitation. What does that look like in central Oregon?

>> Yeah, so we have a really interesting data set from our experimental range just between here and Bend, and we just look at the annual precipitation. Our average for over, you know, 50 years is about 11 inches there. But then, if you actually say, you know, how often does precipitation in a given year fall within, you know, 10% of that mean? And we find out that 75% of the time, it's greater than that 10%. So most of the time, we don't have average precipitation, so like you said, it's really variable. And it goes from, you know, double the amount of precipitation in a year to then less than half of that, and -- is pretty common. So most of the time, we're dealing with -- most of the time, we're dealing with drought, and then we have these few years that bring the average up. And so, that's, of course, a real challenge to management, sustainability of these rangelands, but I do think that if grazing is properly managed, that we generally see that it has very minor, if at all, impacts on plant communities. As we learn more about some of these destructive fires in the lower elevations, and annual grass invasion, we can actually see the benefits of it. Now, that being said, I think, you know, heavy, repeated defoliation in the spring clearly has some detrimental effects to the plant community. If that happens long enough, it will, of course, cause an undesirable shift in that plant community to an annual grass community. So it's all really about the management of the grazing, whether or not it's having a negative impact on the plant community or not, or even having a beneficial impact.

>> And that was going to be my next question. You know, we can say that managed grazing -- or well-managed grazing allows just natural processes to dominate, rather than herbivory, but the million-dollar question is, you know, where is that threshold of grazing that's heavy enough, or too frequent enough, or severe enough that it causes a negative change? And you -- you began to answer that with heavy grazing in the springtime. A couple episodes ago, we talked with Karen Launchbaugh, and then later with Floyd Reed about some grazing rules of thumb that maybe have worked or haven't worked -- the good, the bad, and the ugly. And, you know, one of the things that we talked about was the recent paper by Wayne Burkhardt and Ken Sanders [assumed spellings] looking and trying to do a synthesis of everything that was out there on growing-season grazing of bunchgrasses, specifically. And my take away from that was that they concluded as long as the plants are allowed to produce seed periodically, you're probably going to be okay. And it seems like a lot of what happened across the west, you know, maybe 100 years ago was that we were trying to apply good animal husbandry principles to range management, you know, where you're trying to match the animals' nutrient demand with the forage supply curve. And if you do that, you've got cows grazing spring range potentially every year. Any other thoughts on rules of thumb, or things that a person for sure should not do in order to avoid crossing this threshold where grazing becomes the dominant factor influencing the plant community?

>> Yeah, I think you hit that one right on the -- nail on the head, that repeated spring use, essentially not allowing the plants to complete their life cycle and produce seeds in a year -- that's the one thing that we know for sure we should never do. We've seen with some of our research that we -- even with fairly heavy grazing, that the plants are resistant to that for a number of years. But over time, you'll start seeing them shrink in their base layers. That's -- the crown of the bunchgrass will get smaller and smaller, and at a certain point, then they'll die out of the plant community. Whereas all we have to do is start alternating that season of use, where we're grazing, you know, in the spring for, you know, one year, and the next year, we wait until after they've completed their life cycle and set seed, not interfering with them in that year. And that's -- kind of balances out. The trouble we generally run into is when people, you know, say, "Oh, we'll just reduce the numbers, and we'll still graze the spring one, you know, every spring."

>> Right.

>> And what you see then in that scenario is, yes, there's a lot of the plant communities look fine across that landscape, but the areas they select, they'll select year after year after year. And those areas will suffer. So the best option is to always practice this kind of -- you -- alternating the season of use, and then it doesn't hurt, of course, to apply an infrequent complete rest, and we'll give it a whole year without any grazing, just to make sure all those seeds are getting on the ground. So generally, you know, as a rule of thumb, you know, do that, and then generally take, you know, 40, 50% of the available forage, but no more than that. What we don't know, and it's kind of out in the air, is -- or unsettled, is that -- what happens if we start grazing these dormant seasons, and how heavy can we go there? Because we know we're not taking off actually the growing tissue that's, you know, needed to produce seeds and stuff like that. You know, how much of that can be removed compared to growing-season use is still un-established, so to speak, because clearly, we can take more forage off in the off-season without negatively affecting the plants. It may, then, have -- affect habitat value for species and stuff like that.

>> Yeah, that's interesting, and I'm curious. When people say dormant-season grazing, I associate that with grazing after seed shatter, but sometimes dormant-season grazing is also used to refer to fall and wintertime grazing. Which may be after the plants have begun to green back up, and are -- have a little bit of sort of photosynthetic material, you know, sitting there waiting to get a jump on the spring. I've seen extremely positive results from grazing in what I would call late summer, when the plant has produced seed, and it's dry enough that really nothing's actively growing anymore, but before you get the full green-up. How would you define dormant-season grazing?

>> Yeah, I think we're thinking along the same lines, just when it's not growing. And what we have -- in this part of the world, we really don't have fall green-up generally. Not -- you know, there's years that are exceptional to that of our large native perennial bunchgrasses. We will fairly -- if we have green-up of annuals, we'll probably have green-up of Sandberg's bluegrass. The cows don't really graze it. It's just too short. As a matter of fact, it's generally classified as an increaser. If you graze too hard, it increases in those plant communities. Now, as you do go to areas that are lower elevation, or warmer in the winter than we are here, you would need to be very careful not to apply fall and winter grazing when those plants are actively growing. Because you would run the risk of severely damaging them as they're trying to, you know, start growing, versus if you were planning it in the dry part of the summer. You could really apply a lot heavier grazing with no negative impacts. So that is something that we -- I often refer to it as dormant-season grazing, talking about fall and then winter here, but it isn't the same, you know, if you go somewhere that's warmer or has wetter falls earlier than we do. But generally, you know, here, our plants are pretty -- you know, our large -- bunchgrasses are generally not growing until, you know, February. Right, and sometimes even later, depending on -- not what elevation you're at, but -- yeah, so definitely -- when I'm talking about dormant-season grazing, I'm talking to the physiology of the plant, but this region it generally is fall and winter.

>> Got you. Going back to the discussion about variability, I've seen somebody from Utah State University, maybe one of their experiment stations, gave a presentation at the SRM a while back where they -- they were looking at, you know, 50, 60 years of plant community data. Combining that with precipitation or other weather data, looking for, you know, something that would correlate between meteorological events, or temperature, or precipitation, or something, and attaching that to, you know, a real punctuated change in the plant community. And what they found, as I recall, was that where you had back-to-back years of light spring precipitation, that really drove a marked change in the plant community. The idea was that year one with that high light spring precipitation, when everything is actively growing -- you got a higher percentage of viable seed, and more seed production in total. And then, year two, if you had a second year with above-average light spring precipitation, that germinated most of that seed, and they were able to establish those plants. Do you see anything like that here, any anecdotal or experimental observations about those kind of punctuated changes?

>> Yeah. So we have some long-term data sets from a lot of different Wyoming big sagebrush plant communities, and we do see those that are really driven by precipitation, and especially, like, our forbs. A lot of times, we don't see -- and a lot of these plant communities are in really good shape, so they're not desperately needing to establish new perennial bunchgrasses. But the fluctuation in the forbs is just off the charts, and it all depends on, you know, a year or two of precipitation, and especially, you know, availability in the spring, when they're trying to grow. So it makes a huge difference in those plant communities. We see a similar thing at times, though, with our perennial bunchgrasses, that, you know, they may be -- they'll -- we get a lot of seedlings of perennial bunchgrass almost every year in all these plant communities, but most of them, of course, don't survive. Now, if we get, you know, back-to-back wet springs, usually, then, they survive, and are recruited into the plant community if there's available space. If, you know, it's a full plant community, it's -- they're not going to survive. But if they have, you know, a neighbor that has died out, plant community -- or, like, there's a significant reduction for some reason in that plant community over time, that that's an opportunity to fill it back in. Sadly, a lot of times, we don't get those back-to-back years.

>> Right, right. An agronomist would say that most perennial grasses have to have their seed come in contact with bare mineral soil to germinate. Is that the case, and for native perennial grasses and not just, you know, say, improved irrigated pasture species? And is that a compounding factor with the litter created by invasive annual grasses?

>> Yeah, they need to have good seed-soil contact. I mean, preferably, most of these would have, you know, some seed -- or some soil even over the top of them, which, you know, as they fall naturally from a plant, that usually doesn't happen. But a lot of times, we see the ones that are successful, you know, have fallen into, like, a little crack or something, so they get a really good contact with the soil. And, yeah, if you have a litter layer, and the seeds are getting stuck in it, our natives are not adapted to grow in litter, compared to, like, our exotics, which are. The exotic annuals are well-adapted to grow, you know, through a little layer, or up through it, where ours are slow-growing, and they're not -- they're wanting to be at that nice contact with the soil -- seed-soil surface.

>> Yeah, I saw some data from UC Davis showing that cheatgrass -- the radicle coming off of a cheatgrass seed would go through as much as seven inches of litter in order to go find some moisture, but they would germinate with -- you know, with incredible volumes of litter.

>> Yeah, and the same thing with medusahead. You know, I can pull up medusahead and see a seed in the middle of the -- middle of the litter layer growing root down into the soil.

>> If you were giving advice to a rancher on how to graze healthy rangeland that's not infested with invasive annual grass, to keep it that way, what would you tell them?

>> I'd probably, like -- essentially what I said earlier about the -- grazing it in this kind of pattern where you alternate between season of use. So you're grazing, you know, during the actual growing season, then you're waiting until after seed set, and then, infrequently, just complete periods of rest. I would suggest to a guy that's in an area that has a high risk of wildfires, especially in the lower elevations, you know, where we don't want them to burn for risk of annual grasses -- I would suggest when you have a couple of years of above-average production. That you probably want to really consider, you know, that fall-winter grazing, at least in this area, to reduce that buildup of fuels that would carry a wildfire in the subsequent, you know, coming wildfire season. I think one of the other things that's hard to do, but we have some people that do it, is monitoring your rangelands, and seeing that, you know, either you're not having an effect, or you're having a desirable effect, you know, such as measuring your frequency of perennial bunchgrass, and stuff like that. And making sure that what you're doing is working as you had hoped it had, or if it's not, you know, being ready to make a change. I think too often that our monitoring a lot of times is just us looking out there, saying, "It looks good still, and looks good still." You know what? It doesn't look good anymore, and then we're, you know, too late, whereas if we'd been monitoring, we might have been able to make changes earlier.

>> Mm-hmm. We had a bit of this discussion in the episode with Floyd Reed. We were talking about the book that he coauthored with Dave Bradford and Robbie LeValley, looking at 100 years of change there in eastern Colorado -- western Colorado. And they had repeated photographs that were taken by some early explorers to look at how the landscape had changed over time, and we talked quite a bit about fixed-point repeat photography as a good means of doing long-term monitoring. Do you have any recommendations for ranchers on what they could do to add to the subjective data of photos to provide some objective measurements of rangeland health?

>> Yeah. I know their time's really limited, and so that's where, you know, these fixed-point repeated photography is really useful. I would think in areas that -- if you have a little concern, or you're trying something new, just getting the density of the large perennial bunchgrasses, repeatedly measuring that would probably be a really good way to ensure that you're meeting your objectives.

>> Describe a method for that. Say a belt transect?

>> I would say, you know, something like a belt transect, something you can just walk across. And I know there's other methods out there. I'm more familiar with the ones that are more aligned for statistic analysis, but there are some pretty good ones that -- I think that, are, like, in the rangeland monitoring handbook that would probably be adequate for, you know, that kind of -- you know, just monitoring versus research. But I do know that, you know, there's a lot of extension agents out there that have a lot of experience with this kind of stuff, and matter of fact, some have even developed, you know, kind of protocols for ranchers. And that hitting up those types of guys, and gals for that matter, would be really good for, you know, getting something that they've kind of tested out with ranchers already.

>> Mm-hmm. Yeah, I've heard quite a few ranchers say that they took over a new piece of ground, or changed management, and they almost invariably say, "You should've seen what this looked like 20 years ago," but of course, nobody has any evidence. And they always mean that it looks better than it used to, but without some proof of that, you know, we all have this arbitrary range of rangeland health values. And so, you know, they -- in their mind, maybe it went from a two to a six on a scale of one to 10. But if they're working with somebody who has less history with the site -- you know, say a brand-new BLM range -- or something, and in their scale in their head, they think it's at a four, and they'd like it to be at an eight. And they want to change the management. It seems like it's useful, in those circumstances, for the rancher to have some evidence that what they're describing as positive change has actually been taking place. Have you seen any of that around here?

>> Yeah. I think the trouble is, everyone's so busy that they don't do that, and they're -- especially when they're first starting out, or they buy a new ground. They're desperately trying to financially make it work, and make these improvements, and the monitoring just goes to the wayside. And it's too bad it has, because it is critical when it comes down to proving that you're a good stewardship, or keep on a path that's working. As you said, if you get a new range con coming out there, and it's your -- and he says, "This doesn't look very good," and the rancher's like, "It was terrible when we got it. And what we've been doing is working." And someone new comes in there, and says it looks bad compared to, you know, their ideal rangeland, and so they're wanting to change management to make it better, versus it might already be going in the right direction. But, you know, it's easier said than done. I've personally bought 300-some acres, and it was very weed-infested. I've been doing all kinds of treatments, and seeding stuff, and do I have hardly -- I have hardly any monitoring data. It's like, I have a few pictures, and here, I'm a range scientist. So it's really easy to go by the wayside, so -- but it's well worth it, especially if you're dealing with something that you're not the sole manager of, such as public lands.

>> You've been a range scientist for long enough now that you've quite a few papers with your name on them. How often are you surprised by research results?

>> Usually, the stuff that comes down to publishing, I'm not overly surprised, but before you set up a study, a lot of times you have something kind of -- you know, a mini-scale study going on, or you're doing another study. And you see a surprising result, which makes you think, oh, you know, man, we need to test this out. So I would say there's probably, you know, 25 to 35% of the time when you're doing research -- there's at least something completely unexpected that you can pull out of that. Yes, a lot of stuff we do, we kind of have an idea of what the endpoint might be, but there's a lot of variation out there. And we see new things all the time, and that, a lot of time, drives the next project, which we're trying to potentially confirm what we observed in a different study. So there's a lot of -- there's a lot of variability out there, and a lot of new things. And so, you generally do get, you know, somewhat surprised. Sometimes it's good. Sometimes it's not good [laughter].

>> Yeah, so it's often those preliminary or smaller-scale studies that give you the ideas to pursue with larger-scale, something that's got a statistic setup on it.

>> Yeah, or even just -- you know, you have another large project, and something that really wasn't part of the study pops out. And you're like, oh, man, we've got to actually do a study just to test that, because that might be, you know, a huge deal.

>> What's the favorite part of your job?

>> I think it's seeing people actually use our research to either change management or try to restore stuff. I think actually seeing it be useful to people is my most rewarding part of the job.

>> Yeah, and what do you -- is there anything in particular you'd like to chase down, in terms of research results over the next, say, 10 years?

>> I think one of the biggest challenges we're facing is managing fires and managing annual grasses -- that those ones are challenging, and trying to do them in such a way that it's economically feasible, and then also we achieve desirable ecological outcomes. And that's kind of where I plan on spending probably the rest of my career, working on that, and hopefully perfecting some of that stuff. But that's one of the more challenging issues, but also, I see it as -- any headway in those areas will be very rewarding.

>> Very good. I look forward to seeing that. Dr. Kirk Davies, it's been a pleasure to talk with you. Thank you for your time today.

>> Well, thank you for -- me. It was a pleasure.

>> Thank you for listening to "The Art of Range" podcast. You can subscribe to and review the show through iTunes or your favorite podcasting app, so you never miss an episode. Just search for "Art of Range." If you have questions or comments for us to address in a future episode, send an e-mail to For articles and links to resources mentioned in the podcast, please see the show notes at Listener feedback is important to the success of our mission -- empowering rangeland managers. Please take a moment to fill out a brief survey at This podcast is produced by Connors Communications and the College of Agricultural, Human, and Natural Resource Sciences at Washington State University. The project is supported by the University of Arizona, and funded by the Western Center for Risk Management Education through the USDA National Institute of Food and Agriculture.

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Mentioned Resources

  • The scientists at the EOARC are prolific publishers. This OSU/USDA research station makes their journal articles and research papers available to the public on their website. and
  • Journal article: An Alternative Management Paradigm for Plant Communities Affected by Invasive Annual Grass in the Intermountain West. May 2018 in Rangelands by Berry Perryman, Brad Schultz, Kent McAdoo, Sherman Swanson. Full text available at
  • Implications of Longer Term Rest from Grazing in the Sagebrush Steppe, journal article by Kirk Davies, Martin Vavra, Brad Schultz, and Neil Rimbey. They conclude from a wide literature review that "Not grazing can cause an accumulation of fine fuels that increase fire risk and severity and, subsequently, the probability of sagebrush steppe rangelands converting to exotic annual grasslands. One common theme they found was that shifts in plant communities (i.e., exotic annual grass invasion and western juniper encroachment), caused in part from historical improper grazing, cannot be reversed by long-term rest. This synthesis suggests that land managers should carefully consider if long-term rest will actually achieve their management goals and if a change in grazing management would achieve similar results."…blication/798.pdf
  • Adaptive Management for Invasive Annual Grasses: A Step-By-Step User's Guide for Implementing EBIPM, by Roger Sheley, Brenda Smith, Kimberly Reever-Morghan, and Tony Svejcar. 40pp.…agement%20sm.pdf
  • Grazing Invasive Annual Grasses: The Green & Brown Guide, by Brenda Smith, Roger Sheley, and Tony Svejcar.
  • Post-fire Grazing Management in the Great Basin, fact sheet for Sage Grouse Initiative.…razing.pdf

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