Tag Archives: impacts

Compatibility of Cows, Conservation and Climate Change?

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I’ve been asked a number of times why I advocate for cattle grazing in prairies when cattle are such strong contributors to greenhouse gas emissions and rapid climate change.  It’s a fair question, but also a complicated one.  I don’t have a definitive answer, but I can share some of what makes it a thought-provoking subject.  Rather than providing a lot of specific research citations, I’m aiming instead to provide some general information that highlights the complexity of the topic.  Feel free to contribute additional information and perspectives in the comments section below (as long as you keep it constructive and polite).

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Cattle graze among leadplant and prairie clover at Konza Prairie in the Kansas Flint Hills.  What are the ramifications of cattle grazing for greenhouse gas emissions and other contributing factors to climate change?

Cattle: The Downsides

First, here are some reasons people are concerned about the impact of cattle on climate change.  According to the EPA, agriculture is responsible for about 9% of the U.S. greenhouse gas emissions, and beef production makes the largest contribution to that category.  Most of the impact comes not from carbon emissions, but from methane and nitrous oxide, both of which influence climate change more strongly (pound for pound) than does carbon.  “Enteric methane” (cow burps) is a big part of that equation, but so is manure, urine, and application of fertilizers to pastures.  These emissions are bad enough, but there are other negative impacts from beef production as well, including emissions from growing corn and other feed for cattle, emissions from manure in feedlots, water consumption by cattle and feed production, and pollution from sedimentation and nutrient runoff of pastureland.  Reading a list of bad stuff like this, it’s easy to see how people might wonder why I keep talking about grazing like it’s a good thing.

Cattle

Cattle are sometimes their own worst enemy in terms of advocating for their own existence.  I mean, come on, man!  This is just not a good look.

Predecessors to Cattle

As I provide some counterpoints, I’m going to do so from the perspective of the central Great Plains – the area of the world I’m most familiar with.  Outside the Great Plains, the situation varies greatly; there are places in the world where grazing may not be compatible with local ecosystems, for example, and where forest or other land cover types are being converted to pasture.  Here in my part of the country, however, we are in the heart of the historic bison range.  Before Europeans entered the picture in the Great Plains, prairies here were being grazed by bison, elk, pronghorn, and other large animals.  There are many arguments about the size of those historic bison populations, fluctuations in herd size and geographic range over time, and when/where bison impacts were important for prairie ecology.  For the purposes of this discussion, the important point is that cattle (and their emissions) weren’t introduced into a landscape with no history of methane emissions.  Bison were here prior to cattle, and they burped too.

The most cited article I’ve seen on the issue of methane emissions from historic bison populations is by Francis Kelliher and Harry Clark.  They use a fairly standard estimate of 30 million bison across the Great Plains prior to European contact.  Based on their calculations, the methane (CH4) emissions from those bison (2.2 Tg CH4 year-1) are not hugely different from those of today’s 36.5 million cattle across the same geography (2.5 Tg CH4 year-1).  The exact numbers are less important than this basic idea: the prairie ecosystem was contributing large amounts of methane to the atmosphere before humans brought cattle to the Plains.

Of course, feedlots, fertilization, and forage production, along with all the greenhouse gas emissions and other concerns associated with them, were not part of the historic bison landscape.  We definitely have an obligation to examine those aspects of cattle production and do what we can to limit their negative impacts.  In addition, the fact that cattle on native rangeland are producing emissions similar to their bison predecessors doesn’t release us from the responsibility of trying to reduce those emissions where possible.  I’m hopeful that research over the next decade or so will provide us with more guidance on how we might do that.

Bison

Before there were cattle, bison roamed (and burped) across the Plains.

Get Rid of Cattle?

What if we just stopped grazing cattle on the Great Plains?  Well, since the vast majority of the Great Plains is privately owned, grassland still exists primarily because it produces income.  Without cattle production, much of that grassland would likely be converted to row crop agriculture – a scenario that would probably be worse for climate change and would certainly spell disaster for prairie ecosystems.  Some have argued that a majority of the Great Plains should be turned into public land that would support both wildlife and tourism.  There are way too many economic and social issues associated with that for me to deal with here, but from a climate change emissions standpoint, I’m not sure it would solve the problem.  Either cattle would be replaced by bison again (see previous paragraph) or, if bison were not reintroduced, prairies would suffer from the loss of grazing, a major component of ecosystem function (see next paragraphs).

Simply getting rid of cattle altogether is probably not a great strategy for conservation. Plus, how could you get rid of something this cute?

Simply getting rid of cattle altogether is probably not a great strategy for conservation. Besides, how could you get rid of something this cute?

Grazing as a Positive Force

Despite the fact that chronic overgrazing can cause degradation of prairies (loss of plant species and habitat, soil erosion, etc.), grasslands and large grazers evolved together and grazing is still an essential component of grassland ecosystems.  This is especially true in North America’s Great Plains where there are still grasslands large enough to support wide-ranging wildlife species such as grouse and pronghorn.  Grazing, along with fire and drought, is one of the three major forces that affects prairies and prairie species.  For example, large herbivore grazing helps keep grasses from being so competitive that they overwhelm and reduce the diversity of plant communities, something that leads to a cascade of negative and interconnected impacts on pollinators, productivity, wildlife/insect communities, and more.  In addition, grazing alters vegetation structure, creating a wide range of habitat conditions.  Ungrazed prairie provides fairly uniform vegetation structure, even if it is hayed or burned.  Grazed prairie (under the right management) is heterogeneous, with patches of tall/dense vegetation, patches of short/sparse vegetation, and many other habitat types in-between – allowing the widest possible spectrum of prairie wildlife and insect species to thrive.

Maintaining plant and animal diversity, ecosystem function, and ecological resilience within the historic range of American bison would be very difficult without some kind of large ruminant, and in the face of climate change, we need our grasslands to be as resilient as possible.  Resilient grasslands will better adapt and maintain their ecological functions as climate changes, and that means they’ll continue to pull carbon from the atmosphere and store it belowground – an incredibly important part of our global climate change strategy.  While the impact of grazing on carbon storage of grasslands is, in itself, a complex topic, the general scientific consensus seems to be that a moderate level of grazing facilitates more carbon storage than no grazing (and more than chronic overgrazing).

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Strategic cattle grazing can create a variety of wildlife habitat structure types and help sustain plant diversity and ecological diversity.  It can also help maximize carbon storage in grasslands.

The Upshot

In the Great Plains of North America, grazing is an essential part of grassland ecosystems – a component that maintains the ecological health and resilience of prairies.  Cattle have mostly replaced bison as the large ruminant on stage at the moment, but they are filling many of the same basic roles – regulating plant competition and creating wildlife habitat, and also pooping, peeing, and burping.  We absolutely need to find ways to minimize the impacts of today’s grazing on climate change.  Livestock confinement operations, pasture fertilization, forage production, and other related practices provide opportunities for continued improvement.  In addition, some rangeland grazing practices, such as chronic overgrazing, are known to be detrimental, and not just from a climate change standpoint, so that’s an obvious place to focus.  Beyond that, we need to figure out how best to limit methane and nitrous oxide emissions and increase carbon storage on rangeland.  That will likely mean changing techniques for managing cattle in pastures, but also dealing with issues related to pasture fertilization, forage production, forage and animal transportation, feeding operations, and more.

The topic of cattle grazing and climate change is incredibly complex.  There is much more involved than I could possibly cover here, and what I did include is plenty complicated.  I don’t pretend to fully understand all the facets of the issue, but for now, I feel comfortable in my stance that cattle (and/or bison) grazing can be compatible with responsible conservation of our prairies here in the Great Plains.

 

More Information and Acknowledgements

Several scientists from The Nature Conservancy wrote a really helpful piece on the beef supply-chain and its impacts on water, wildlife, and climate.  You can see a summary and get access to the full report here.

Special thanks to Jon Fisher and Joe Fargione, who both helped me refine and improve this post.  Any remaining errors are my fault, not theirs.

 

The Much Maligned Coyote

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Here in Nebraska, we’ve lost most of our largest predators.  Bears and wolves are gone (excepting rare long-distance wanderers).  Mountain lions are making a slow comeback in the northern and western parts of Nebraska, but the agricultural character and fragmented nature of our state makes it difficult to imagine a much stronger presence of large predators than we have right now.  That’s not a critique – it’s just reality.  It’s difficult to know what effect the absence of those predators has on our wildlife and natural landscapes, but based on what we know from research elsewhere, it’s surely significant.  Throughout the world, and across a wide range of habitat types, major predators stimulate complex cascades of impacts far beyond simply suppressing the populations of their favored prey species.  In fact, the diversity and abundance of many plant, invertebrate, and wildlife species have been shown to decline dramatically when dominant predators disappear.

Illustration by Kim Tri

Coyote illustration by Kim Tri, one of our Hubbard Fellows and, obviously, a talented artist.

Today, in the absence of wolves and bears, coyotes have stepped into the role of top mammalian predator across much of Nebraska.  It’s hard to know if they are as effective as their larger counterparts at maintaining ecosystem function, but there is strong scientific evidence for the strong and positive impacts coyotes have on a number of other grassland species.  Much of the research on this topic was published 15-20 years ago, but few people seem to be familiar with it.  In fact, rather than being celebrated for their importance, coyotes are widely reviled, and often shot on sight, by many (most?) rural citizens across much of prairie regions of North America.

There is much unfortunate irony in the vilification of coyotes.  One common coyote narrative is that coyotes are hard on nesting birds, especially game species like pheasants, quail, turkeys, grouse, and ducks.  In reality, coyotes feed mainly on rodents, and the major predators of birds and their nests tend to be smaller animals, including foxes, raccoons, and cats (especially feral house cats).  Coyotes are large and aggressive enough to intimidate or kill those “mesopredators”, keeping their numbers low and driving them into areas where coyotes spend the least time, such as wooded draws, farmsteads, and even surburbia.  In fact, numerous studies have documented detrimental impacts to bird populations ranging from songbirds to ducks and grouse when coyote numbers are suppressed and mesopredator populations swell.

One of the most dramatic studies of coyote impacts on the structure and function of ecological communities took place on 20,000 hectares of west Texas land back in the 1990’s.  Researchers halved the number of coyotes in one portion of the study area and left the population alone elsewhere.  Within a year of coyote control, the area with fewer coyotes experienced higher populations of bobcats, badgers, and gray foxes.  Perhaps as a result, 11 of the 12 rodent species in that area disappeared, leaving only a skyrocketing population of kangaroo rats.  Jackrabbits also tripled their numbers in the coyote control area, much to the chagrin of ranchers, since jackrabbits compete with livestock for forage.

Another great coyote illustration by Kim Tri.

Another great coyote illustration by Kim Tri.

Speaking of ranchers, many tend not to be coyote fans, in large part because coyotes are sometimes hard on livestock.  Sheep ranchers can suffer big losses to coyotes if they don’t actively protect sheep with dogs, overnight enclosures, and other strategies.  Cattle ranchers can also have trouble with coyotes killing livestock, especially just-born calves.  Coyotes are very good at killing young deer fawns – a great reason for prairie enthusiasts to be coyote fans, by the way – but some transfer that skill to calves as well.  While any self-respecting cow can protect her calf from coyotes under most circumstances, even the toughest mother is weakened enough by the process of giving birth that she is vulnerable to a quick sneak attack.

Unfortunately, the response to livestock losses is often the indiscriminate killing of whatever coyotes ranchers can find.  Research has shown that kind of “coyote control” to be largely ineffective, in part because it usually fails to kill the individuals actually causing problems.  For example, a fourteen year study showed that almost every sheep killed by coyotes was taken by the “alpha pair” in the pack’s social structure.  Those alpha animals are also the wiliest and most difficult to kill.  Furthermore, of course, in the unlikely event that coyote control efforts succeed at suppressing the population in an area, the results might not turn out in favor of the rancher.  Higher numbers of raccoons and foxes, not to mention jackrabbits, along with fewer ducks, grouse, and quail, might take the thrill out of the temporary victory.

Even if coyotes gain wider recognition for their positive effects on natural systems, however, the relationship between coyote and human is bound to be complicated.  As we continue to alter their habitat, coyotes will continue to adapt and survive as best they can.  At times, that will bring them into conflict with us.  It is understandable, for example, that a rancher needs to address livestock losses, and sometimes that could mean tracking down and killing the individual coyote(s) responsible.  However, that kind of careful, targeted response is much different (and more effective) than current broad, indiscriminate campaigns against an animal whose bad reputation is largely based on innuendo and misinformation.

Ideally, seeing coyote tracks on their property would be a positive experience for landowners.

Ideally, seeing coyote tracks on a property would be a positive experience for landowners.

Coyotes and other predators play critically important roles in grassland ecosystems.  It’s easy to understand how they directly suppress populations of their primary prey species.  However, as we continue to study predators, we find more and more of the kind of indirect impacts that ripple through ecological systems in ways that are difficult to predict.  While it seems unlikely that wolves and bears will ever return to prominence in Nebraska or most other prairie regions of North America, coyotes may be able to cover at least some of the ecological roles those larger predators once played.

But only if we let them.