Does Cattle Grazing Preclude Large Blazes?

If cattle graze to bare soil, it is true that fires are slowed under such conditions, but the ecological impacts are enormous. Photo George Wuerthner 

When I worked for the BLM, us “ologists” (hydrologist, ecologists, biologists, archaeologists, geologists, and botanists) used to refer to Range Conservationists as Range “Cons” because they conned the public into believing many myths about livestock grazing.

It’s essential to keep in mind that range cons have a financial conflict of interest. If there are no cows, there is no reason to have a range conservationist on the payroll. So, what you will see over and over is that range cons will do just about anything to maintain cows on the range. And they don’t mind spending your money (taxpayer) to make this happen. Most range cons (and range professors) see their allegiance to the livestock industry, not the public interest.

One of the “cons”  heard continuously from range conservationists and repeated by uninformed media is that grazing can help preclude large “mega” fires by “reducing” fuels. This is one of those many assertions that have a grain of truth but is nevertheless misleading.


Whenever you read such pronouncements, be skeptical. Almost all the “evidence” for the value of grazing to reduce wildfires comes from government apologists with connections to the livestock industry.

Many of the studies purporting to demonstrate the influence of livestock grazing on fire spread were done on small experimental plots of land. The transfer of these findings to the larger landscape scale is questionable.

For instance, in an experimental study of cattle grazing impacts on fire, 90% of cheatgrass in plots was consumed during the “boot” stage. These grazed plots were then burned and found to slow or stop fire spread (Bailey, Derek W., et al. 2019). The problem with this and many other experiments is that given a choice, livestock will not consume cheatgrass except early in the spring while green. So, getting cattle to remove 80-90% of the grass except in experimental plots is unlikely.

Another problem is keeping cattle on the desired target area–typically this is done by transporting cattle by truck to the target site, then herding or using moveable fences to keep cattle grazing focused. All of this adds immensely to the cost of any livestock grazing operation. Most ranchers are simply not interested in spending that kind of money to get a bit of cheap forage.

Furthermore, the process of getting the cattle to remove such a high percentage of cheatgrass would decimate soil biocrusts, which slow or prevent cheatgrass establishment. Since cattle prefer to forage on native perennial grasses, if a site had any native species left, they would disproportionately be grazed, harming their competitive ability to survive cheatgrass invasion (Reisner, Michael D., et al., 2013).

In another widely cited study in Arizona, the researchers had several small plots (several acres in size). They compared the fuel remaining after fields were grazed with non-grazed plots. They concluded (with modeling) that light utilization (26%) in treated sites, the BehavePlus fire model predicted that herding reduced fire rate of spread by more than 60% in grass communities and by more than 50% in grass/shrub communities (R.A. Bruegger et al. 2016).

There are several misleading implications of this study. As in the previous study, the experiment was done on small plots where grazing was monitored and tightly controlled. This kind of monitoring and control does not exist on most public lands or even private land parcels.

But the real problem with this and many other studies that presume to show a livestock-grazing induced reduction in fire spread is that they do not work under extreme fire weather.

Bruegger and colleagues admit as much in their next to the last paragraph: “Although it is a promising tool for altering fire behavior, targeted grazing will be most effective in grass communities under moderate weather conditions.”

The weather factors are significant because nearly all massive wildfires burn under “extreme fire weather conditions.” Under such conditions, targeted grazing, prescribed burning, thinning of forests, and fuel breaks, fail to contain or stop fires. In attempting to reduce fuels, such prescriptions often lead to more fire-prone species like cheatgrass.

Extreme fire weather conditions—drought, high temperatures, low humidity, and most importantly, high winds- overwhelm all fuel reductions.  The problem for Americans is that climate change is driving large blazes, not fuels.

Windblown fire races through grazed grasslands near Helena, Montana. Photo George Wuerthner 

In an overview of various fuel reductions, the researchers (Reinhard et al. 2008) concluded that: “Extreme environmental conditions …overwhelmed most fuel treatment effects. . . This included almost all treatment methods including prescribed burning and thinning. . .. Suppression efforts had little benefit from fuel modifications.”

Although they primarily examined forest management options, the same necessary conclusions apply to reducing fuels on rangelands (Williamson, Matt. A. et al., 2019)

Other evidence is simply anecdotal. Cattle graze a strip of cheatgrass. A fire arrives, and the fire slows or is easily suppressed by firefighters. An example is here found with the title Firefighting Catt: Targeted grazing creates firebreaks in cheatgrass.

Without knowing the circumstances of the fire’s burn and weather conditions at the time, one can’t assume that grazing had anything to do with the fire’s behavior. Did the wind shift directions or simply stop. Was the fire even burning under “extreme conditions” which are the only times you have large fires-the very fires that cattle grazing advocates are suggesting grazing is effective in halting or slowing?

Typically, under extreme weather conditions which always includes high winds, any wind-blown fire spews embers up to a mile or more beyond the burning front.  Such a blaze will easily skip over a strip of grazed land, making such fuel breaks or targeted grazing ineffective.


Severe grazing can reduce fuels that would allow fires to spread. Still, grazing to this level creates a lot of collateral damage, including soil compaction, which reduces water infiltration (Warren, S.D. et al., 1986, Belsky et al. 1999), social displacement of native herbivores like elk and deer (Clegg 2014, Frisina 1992), water pollution (Carter, 2002), destruction of riparian areas (the green line of vegetation influenced by water) (Kauffman et al 2001, Kauffman 2004), consumption of plants needed by other wildlife like forbs consumed by sage grouse (Doherty et al. 2014), and reduction of hiding cover for wildlife, and many other impacts (Fleischner 1994, Freilich et al., 2003).

Collateral damage from livestock grazing includes cattle damage to riparian zones (the green vegetation area near water). Photo George Wuerthner 

It is important to note that much of the grassland/shrub ecosystems of the western United States west of the Great Plains evolved in the absence of large herds of grazing herbivores like bison (Mack and Thompson 1982), thus are vulnerable to heavy grazing pressure.

Alternatively, and far more critical these days, livestock grazing is one factor in the spread of cheatgrass, an annual exotic that is extremely flammable (Belsky, A.J. and J. L. Gelbard, 2000). Merriam et al. (2006) found that nonnative plant abundance was considerably higher on fuel breaks than in adjacent wildland areas, especially when the heavy ground disturbance was involved, providing a potential vector for weed invasion

Therefore, cheatgrass has increased fire frequency in sagebrush ecosystems, causing complete type conversion of sagebrush steppe in many areas (Reisner Michael D. et al. 2013).

Cheatgrass surrounds a relict perennial native grass. Photo George Wuerthner 

The factors that favor cheatgrass spread, including livestock grazing. Selective grazing of preferred perennial grasses reduces their competitive abilities, permitting cheatgrass colonization (Maestas et al. 2019)

Besides, biological soil crusts (BSC) found in the interspaces between bunchgrasses inhibits cheatgrass establishment. Cattle trample these BSC (Root, Miller, and Rosentreter. 2019).

Biological crust covers the surface of soil. Cattle trampling crusts creates habitat for cheatgrass establishment. Photo George Wuerthner

Maintaining healthy stands of perennial grasses has been shown to inhibit cheatgrass spread (Strand et al., 2017).

Another study that looked at fuel breaks created by targeted grazing and other measures like bulldozing native vegetation cautioned that the “cure might be worse than the disease” since the destruction of soil biological crusts and loss of native grasses that occur with targeted grazing, bulldozing. Other fuel reductions create a disturbance habitat that favors the spread of cheatgrass.

Fuel break on BLM land creates the ideal habitat for cheatgrass establishment. Photo George Wuerthner

The authors cautioned: “these projects could also add thousands of kilometers of new fuel breaks to the region over the next decade or two, directly altering hundreds of thousands of hectares through habitat conversion, and indirectly affecting sagebrush plant and animal communities through the creation of new edge effects and habitat fragmentation” (Shinneman et al. 2018).

Furthermore, the probability that any area “treated” by targeted grazing and other fuel reductions will encounter a blaze when fuel removal is effective is extremely small (Rhodes and Baker 2008). Thus, targeted grazing and further fuel reductions, which have their own set of impacts, occur now, potentially reducing a fire that may or may not come in the future.


Using livestock grazing to preclude large wildfires is an ineffective means of coping with blazes. Livestock grazing has little influence on large-scale blazes, primarily driven by extreme climate/weather events. The probability that a large fire will encounter a recently grazed area is small, but livestock grazing’s ecological impacts are enormous and assured. The best way to reduce wildfire’s threat is to fire-safe the home and ultimately reduce global climate warming, driving many of the more enormous blazes experienced in the West.



Belsky, A.J., A. Matzke, and S. Uselman. “Survey of Livestock Influences on Stream and Riparian Ecosystems in the Western United States.” 1999. Journal of Soil and Water Conservation, Vol. 54. Online. Aug 25, 2003.

Belsky, A.J., and J. L. Gelbard, 2000. Livestock Grazing and Weed Invasions in the Arid West, Oregon Natural Desert Association, Bend, Ore, USA, 2000.

Bruegger, Retta A. et al. (2016). Targeted Grazing in Southern Arizona: Using Cattle to Reduce Fine Fuel Loads Rangeland Ecology & Management Volume 69, Issue 1, January 2016, Pages 43-51

Carter, John. 2002. Stink Water: Declining Water Quality Due to Livestock Production. In Welfare Ranching: The Subsidized Destruction of the American West Edited by George Wuerthner and Mollie Matteson.

Clegg, Kenneth. 1994. Density and Feeding Habits of Elk and Deer in Relation to Livestock Disturbance Master of Science Utah State University.

Diamond, Joel, Christopher A. Call, and Nora Devoe. 2009. Effects of targeted cattle grazing on fire behavior of cheatgrass-dominated rangeland in the northern Great Basin, USA International Journal of Wildland Fire 2009, 18, 944–950

Doherty, Kevin, David E. Naugle, Jason D. Tack, Brett L. Walker, Jon M. Graham, and Jeffrey Beck. 2014. Linking conservation actions to demography: grass height explains variation in greater sage-grouse nest survival.  Wildlife Biology, 20(6):320-325. 2014

Freilich et al., 2003. Ecological Effects of Ranching: A Six-Point Critique. August 2003 / Vol. 53 No. 8 • BioScience 759

Fleischner, Thomas. 1994. Ecological Costs of Livestock Grazing on Western North America. Conservation Biology 8, no. 3629-644.

Frisina, M.R., 1992. Elk habitat use within a rest rotation grazing system. Rangelands 14(2) 93—96.

Kauffman, J. B. 2001. The multiple influences of riparian/stream ecosystems on fires in western forest landscapes: summary report. Rocky Mountain forest and Range Experiment Station, Stream Systems Technology center, Ft Collins, CO. 209p

Kauffman, B., Andrea Thorpe, and Jack Brookshire. (2004) LIVESTOCK EXCLUSION AND BELOWGROUND ECOSYSTEM RESPONSES IN RIPARIAN MEADOWS OF EASTERN OREGON Ecological Applications, 14(6), 2004, pp. 1671–1679 q 2004 by the Ecological Society of America

Mack Richard N. and John N. Thompson. 1982. Evolution of the Steppe with few large, hoofed mammals The American Naturalist. Vol 19. No. 6.

Maestas, Jeremy,  Mike Pellant, Lance Okeson, Derek Tilley, Doug Havlina, Trisha Cracroft, Brendan Brazee, Mark Williams, and Derek Messmer (2019) Technical Note: Fuel Breaks to Reduce Large Wildfire Impacts in Sagebrush Ecosystems. Boise, Idaho..

Merriam, K.E, Jon Keeley, and Jan l. Beyers. Fuel Breaks Affect Nonnative Species Abundance in California Plant Communities. Ecological Applications, 16(2), 2006, pp. 515–527

Reinhardt etc. (2008) Objectives and considerations for wildland fuel treatment in forested ecosystems of the interior western United States.

Reisner, Michael D. et al., 2013.  Conditions are favouring Bromus tectorum dominance of endangered sagebrush steppe ecosystems. Journal of Applied Ecology 2013

Root, Heather et al., 2019. Grazing disturbance promotes exotic annual grasses by degrading soil biocrust communities. Ecological Applications, 0(0), 2019, e02016

Shinneman, Douglas J., Cameron L. Aldridge, Peter S. Coates, Matthew J. Germino, David S. Pilliod, and Nicole M. Vaillant. 2018. A Conservation Paradox in the Great Basin—Altering Sagebrush Landscapes with Fuel Breaks to Reduce Habitat Loss from Wildfire. Open-File Report 2018-1034 Frontiers in Ecology and the Environment

Strand, E. et al., 2017. Do perennial bunchgrasses competitively exclude Bromus tectorum in post-fire rehabilitation across spatial scales? Fire Science JFSP PROJECT ID: 15-2-01-22

Warren, S.D. et al., 1986.  The Influence of Livestock Trampling under Intensive Rotation Grazing on Soil Hydrologic Characteristics. JOURNAL OF RANGE MANAGEMENT 39(6). November 1966

Williamson, Matt. A. et al., 2019. Fire, livestock grazing, topography, and precipitation affect occurrence and prevalence of cheatgrass (Bromus tectorum) in the central Great Basin, USA Biol Invasions,-vols() 0123458697().,-volV)


  1. Maggie Frazier Avatar
    Maggie Frazier

    Mr. Wuerthner, do you consider wild horses to be as damaging to these areas as livestock is? I would think that with enough predators in the area (as there are not in allotments) and the fact that wild horses wouldnt hang around a riparian area any more than other wildlife would that they might be a better answer to this problem. Along with the fact that their digestive systems are completely different than cattle.

  2. Beeline Avatar

    In my experience the threat of fire, no matter how unreal, was routinely used by livestock lessees as one of their primary arguments to increase grazing on public lands.

    Maggie’s right. I think that the authorship here should do a comprehensive article on the “wild” horse problem. The amount of over-grazing is sacrificing the future of wildlife on public lands. I’ll throw in a couple quotes below.

    “We are living off the ecological interest that was generated by a healthy ecological bank account long ago, but we are eating up the principle of that account at a steady and alarming rate”. Prof. Doug Tallamy, Ecologist University of Delaware

    “Wild horses are the most wicked natural resource problem facing the West” T. Messmer Utah State University

    “When looking at the effects of intensity of use, our study shows that an individual horse can have a greater effect of riparian attributes such as stream bank disturbance, vegetation height and plant biomass than an individual cow”. Rangelands 40(2)8pages

    “Laws and policies that mandate the continual presence of an invasive species (horses) unduly affect the ability of wildlife professionals to effectively manage and promote healthy native wildlife populations and habitats. They divert resources- both human and financial from the management of native species, undermine the principles of wildlife biology/conservation and harm the public credibility of wildlife biologists”.

    “Feral horses value to society must be weighed against their ecological costs” Beaver & Aldridge 2011

    AS of December 2018 the BLM had set the Appropriate Management Level of horses at 26,690; the actual number on BLM managed range was 81,951 or more than three times the recommended carrying capacity. And there were 50,873 horses already in off range holding areas. from Congressional Research Serviced Report.

    The wild horse and burro program is probably the most expensive single species program ever devised. The BLM’s budget for this program was said to be 75 million for FY 2018. A super subsidy for a kind of re-invented “super” species that has been granted a special status that over shadows even the Endangered Species Act. The heavy load of this program should not fall on the tax payers back any longer.

    We need an honest reality check and not a bunch of hyperbole on this subject.

    1. Maggie Frazier Avatar
      Maggie Frazier

      Yes this program likely IS the most expensive program. The BLM’s “budget” is nothing more than an excuse for the roundups & warehousing of wild horses. AND we only have the BLM’s voice with the number of actual wild horses on public or forested lands (and FS). Rangeland’s comparison between one horse & one cow? But its never only one cow – at least not in the pictures of livestock on public lands – its many & they hang at water sources.
      The title of “feral” – which I seem to remember as meaning wild – is given by any source that lines up with the livestock lobby.
      I will go online & read the articles though. Yes an HONEST reality check.

      1. Maggie Frazier Avatar
        Maggie Frazier

        Found Dr. Messner at Utah St. Univ. but couldnt find anything authored by HIM that made that statement – found an article by the Wildlife Society (an organization that is definitely opposed to wild horses) telling about all the damage the horses do but sounded like the horses were all alone – no livestock anywhere? – The WS appeared to be horrified that there was a CNN program that actually told the wild horse side of the story as opposed to cattlemen!
        I have to say hearing about the AML – the BLM’s “managing system” – I always wonder how they come up with a figure for the horses yet continue to put greater numbers of cattle on these same areas.
        The excuse is: the cows are only there part of the time – IF there are no trespass ranchers. And there would seem to be!

  3. Chris Zinda Avatar
    Chris Zinda

    Here goes GW again, parsing “conservation,” never mentioning preservation.

    The only “cons” are conservationists implying they are preservationists, never providing a clear moral choice, constantly muddying the water.

    “Preservation” will never happen as long as GW and others continue to self identify as conservationists. That, after years of bugging him regarding this semantic, he continues to use the terms incorrectly means nothing will change.


George Wuerthner is an ecologist and writer who has published 38 books on various topics related to environmental and natural history. He has visited over 400 designated wilderness areas and over 200 national park units.

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George Wuerthner