Is Fire Really Essential in Prairies?

How critical is fire to the health and survival of prairies? 

I think the answer might depend upon whether we’re talking prairie, as in the ecosystem, or a prairie, as in an individual patch of grassland.  It might also depend on whether we’re talking about history or the present.

Prairie fires have been an integral part of prairies for a very long time.

Here are some things I think are true about fire in prairies:

  • Fire is one of three major forces (along with climate and grazing) responsible for creating, shaping, and sustaining prairie landscapes.
  • Fire can influence the competition between woody plants (trees and shrubs) and herbaceous plants (grasses, wildflowers, etc.) in grasslands.  It can outright kill some woody plants (such as eastern redcedar) and top-kills others, forcing them to restart their growth at the ground’s surface.
  • Fire can also affect competition between herbaceous plants.  A dormant season fire can speed up and enhance the growth of early spring plants.  A growing season fire can suppress the growth of plants that are active at the time of the fire.  Plants that begin their seasonal growth spurt right after the fire benefit greatly because it removes many of their competitors for light, nutrients, and moisture. See here for more on the timing of fires.
  • Fire can remove litter (dead vegetation from previous years), exposing the soil beneath.  Sunlight hitting that soil can increase microbial and root activity, making nutrients more available to plants and triggering seed germination among some species. 
  • Fire releases bound-up nitrogen from dead vegetation, sending most of it into the air as part of the smoke.  Other nutrients, including phosphorus and potassium, tend to stay behind in the ash.
  • Fire alters habitat structure by removing aboveground plant material.  This has varying effects, both short-term and long-term, on animals and plants.
  • Fire attracts large herbivores, if they are present, because of the nutritious fresh growth of plants following a burn event.  If both burned and unburned areas are available, large grazers focus their time in the most recently burned areas.  This adds another layer of complexity to the impacts of fire on habitat.
  • Most importantly, fire has been used as a land management tool by people for as long as today’s prairies have existed.  Since the end of the Pleistocene era (aka Ice Age) and the re-emergence of prairies in central North America, people have actively managed those grasslands with the strategic use of fire.  As a result, people and prairie are intrinsically intertwined.

With all that in mind, I think it’s fair to say that fire was an essential component in the development and persistence of the prairie ecosystem in central North America.  The consistent occurrence of fires set by people, as well as through lightning, probably kept prairie from becoming woodland.  That’s especially true in the eastern half of the prairie region, where drought tends not to be frequent or prolonged enough to suppress invasion by trees and shrubs. 

Eastern redcedars like this one are easy to kill and control with fire. Many other species can be suppressed, but regrow quickly after fire.

In addition, the relationship between fire and large grazers created a shifting mosaic of habitat conditions for both animals and plants.  Across an immense grassland landscape those shifting conditions helped sustain a rich diversity of species and a resilient ecosystem.  The impacts of fire (and grazing) on nutrient cycling was also a major part of that story.

At least historically, then, fire was essential to the function and survival of the prairie landscape.  What about today?

This is where it gets tricky. 

I think it’s essential to have fire as an available tool for managing prairies, just as it has been for thousands of years.  There is no question that fire can be an efficient way to combat woody encroachment in grasslands, though it is not always sufficient on its own – especially as shrubs become increasingly competitive with rising levels of atmospheric carbon dioxide.

Fire is unquestionably an important tool for prairie managers.

In addition, fire can still influence grazing patterns and behavior in important ways.  There is ample evidence that patchy fires, combined with large herbivore grazing, can create important habitat heterogeneity, even on a relatively small scale (20 or 30 acres or less).  In large prairie landscapes, where bison or cattle can roam over thousands of acres, patch-burn grazing may be the best approach we have for creating the kind of shifting habitat mosaic that seems to sustain diversity and resilience.

But – is fire really essential for the management of individual prairies?  I think about this a lot because our family prairie has never seen fire, as far as I know.  That’s true at least as far back as the early 1960’s when the majority of it was replanted to grassland after being farmed (there are scattered unplowed patches of prairie as well).  I could use fire at our prairie, but I don’t – primarily because I burn so much at work that the idea of trying to find the time and energy to also burn our own prairie seems overwhelming.

Despite that lack of fire, I’ve seen positive progress in terms of plant diversity and I feel really good about the habitat being provided and used by animals, including vertebrates and invertebrates.  In our case, we manipulate cattle grazing with fences (using the open gate rotation approach I’ve discussed before) and create a shifting mosaic of habitat.  We control woody encroachment by manually cutting trees, sometimes aided by herbicide for species that regrow after being cut. 

Ours is not a unique story.  I’ve seen many other prairies with far greater plant and animal diversity than ours that have not seen fire for many decades.  Some are managed with grazing, others with haying, and woody encroachment is controlled by some combination of cutting and herbicides, as needed. 

If you’re concerned about the use of herbicides, I’ll add here that there are plenty of prairies managed with frequent fire that are still losing ground to trees and shrubs, and that manual cutting/shredding and herbicide use are necessary components of management success.  In other words, the use of fire by itself is often not sufficient on its own. Also, in some prairies where frequent fire is holding back woody encroachment, there are significant concerns about how that fire frequency is negatively impacting populations of plants and animals.

So, what’s missing from these prairies that aren’t being burned?  I’ve asked this question to many people with lots of expertise in fire and prairie ecology.  To date, I’ve not heard an answer that has pushed me to make fire a bigger priority on our family prairie or to push harder on other landowners/managers to do the same.  Please chime in if you think you’ve got a convincing argument.  I’m not saying fire isn’t necessary, I’m just saying I am not currently convinced that it is.

The answer to my question matters because training, equipment, neighborhood attitudes, and other factors make prescribed fire a real challenge for many landowners.  Even for conservation organizations and private landowners who have invested in everything needed to conduct fires, weather and other logistics still present lots of complications. 

Can ranchers and other prairie managers give prairies what they need to thrive without fire? Or is prescribed fire a necessary part of good management?

If we say the only way to manage prairies effectively is to include the use of prescribed fire, that’s a tall order, and one that is probably not feasible for most landowners.  It will also likely alienate many people who think they’re doing a pretty good job of prairie management without fire.  We’d better be really sure before we tell those folks their work is insufficient.

To sum up, fire was one of the major reasons prairies developed and persisted following the last ice age.  Indigenous people’s strategic use of fire helped keep grasslands from becoming overwhelmed by trees and created the dynamic habitat and species diversity that maintained prairie resilience.  Today, fire continues to be an effective tool for maintaining the health of prairies, and I think it’s essential that prescribed fire is available as an option for all landowners and land managers. 

However, while it might seem heretical to some, I am not convinced that fire is an essential tool for all prairies.  Or at least, I’m not convinced that prairie managers can’t maintain diverse and resilient prairies without the use of prescribed fire.  I’d be happy to be proven wrong.

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About Chris Helzer

Chris Helzer is the Director of Science for The Nature Conservancy in Nebraska. His main role is to evaluate and capture lessons from the Conservancy’s land management and restoration work and then share those lessons with other landowners – both private and public. In addition, Chris works to raise awareness about the importance of prairies and their conservation through his writing, photography, and presentations to various groups. Chris is also the author of "The Ecology and Management of Prairies in the Central United States", published by the University of Iowa Press. He lives in Aurora, Nebraska with his wife Kim and their children.

44 thoughts on “Is Fire Really Essential in Prairies?

  1. Now you’ve opened a hornet’s nest. I have met some folks that are absolutely adamant about having to burn (and I’m guessing you’ll here from them), but I’m with you on this. Fire is a great tool to have in the arsenal, but all is not lost if you can’t or don’t use it.

  2. In general I agree. As long as there’s some sort of periodic consumptive use and the “local” ecosystem/one’s own prairie isn’t taking a nose dive off in the wrong direction over a topping point that can’t be fixed… Spend your resources elsewhere, with family enjoying the prairie.

  3. Personally I believe that fire in a well functioning grassland/prairie is only necessary when grazing and/or haying just isn’t possible.
    In that situation the buildup of dead plant litter over time, will suffocate most of the less competitive species.
    And the problem with fire for the ecosystem is of course that a lot of vertebrates and invertebrates will be killed off in the process. Too frequent fire is not good in any case.

  4. Hmm…thought provoking. I’m not a professional land manager. However, I own and manage a small prairie in SE Nebraska near Lincoln. I add that piece about where I’m at because I think every place has it’s own set of influences that affect the relative need or value of fire. I use frequent fire as a management tool on my property to maintain an inventory of over 100 native plant species while retaining a regionally imperiled population of Regal Fritllary butterfly. A major factor influencing that approach is the lack of woody plant management on many adjacent properties. The seed rain is intense. What’s happening in my neighborhood is the value of the land is not exclusively driven by ag production potential or sustainability. Many of the former pastures/prairies in the area that survived the plow have been subdivided into smaller parcels that have become acreages (including my own). Much of the land is owned by investors (often absentee) who lease the land in transition to farmers who are simply there to make a buck. Once subdivided, cutting hay or pasturing stops and those little woody plants held back by former land management are released. Many acreage owners then leave the land “go to nature” welcoming the weed trees on their property to provide privacy. Road rights of way are full of weed trees that see almost no management at all.

  5. Where a piece of prairie is starting from (past management and current species composition) can result in different answers. I don’t think there is a single answer that would be correct for all prairies. Many prairies lost their fire dependent species or landscape structure long ago. Here on the Texas coast where we get 52+ inches of rain and have a year round growing season, fire appears to be essential for some plant species to remain common enough to be ecologically relevant. The further east and the more common natural fire is, the more numerous these species become.

    Hay cutting is probably a very good replacement for fire and grazing. Mowing/shredding alone seems to lead to an impoverished forb community at least in SE Texas.

    An important consideration is that unlike tractors and mowers and even cattle to some extent, fire is applied without the possible extensive spreading of invasive plant propagules.

  6. Another excellent, thought-provoking piece, Chris. Having spent a good part of my career setting fires in prairies (as I know you have as well), in the last several years I have found myself mulling over many of the same points you raise here. I’d like to add a couple of additional thoughts that I think need to be emphasized when considering the use of fire in these systems.

    First, I think it is imperative that managers be as explicit as possible in describing what they are hoping to achieve through the use of fire, and then follow up their burns with a careful evaluation of the degree to which such objectives were actually achieved. Too often, I think prescribed fires are conducted largely based on the rationale that prairies (and the species and processes that comprised them) historically required fire, and that reintroducing fire will bring them back or improve their condition. This logic may or may not be accurate, and its validity depends on numerous factors that need to be examined closely, such as fire season, frequency, intensity, time since last burn, fuel availability, landscape context, native seed availability, impacts of non-native species, status of target species and populations, interactions with other factors – the list is extensive.

    It is especially critical that managers pay attention to factors that may differ considerably from their historical condition, and which therefore may result in quite different outcomes. Perhaps the most important of these in the area in which I now work (the Pacific Northwest) is the presence of non-native species, many of which tolerate or are encouraged by fire. Prescribed burning alone may do little or nothing to control many unwanted exotics and may, in fact, produce exactly the opposite result. Many native species have been absent (or nearly so) from our prairies for so long that there is little or no seed present that would enable them to re-establish following fire, and even when present, may be so seed-limited or otherwise constrained that they cannot compete with abundant non-natives. Other important factors may differ greatly from their historical condition as well. Where prairies have been reduced to fragmented, discontinuous patches, the metapopulation dynamics that once permitted organisms to repopulate burned areas from adjacent patches may no longer be operative. The absence today of Native American harvesting (camas bulbs in our area) likely presents a significantly different fuel bed on which burns occur than what was present when millions of bulbs were annually dug.

    These are just a few of the factors that can result in prescribed burns producing very different outcomes than what may have occurred historically. From my experience, the most common mistakes we have made and continue to make when applying fire to prairie systems (and I include myself in this) is a failure to carry out all of the following: 1) Develop a clear, prioritized picture of desired fire outcomes, 2) Accurately assess current conditions and how they may differ from historical conditions, 3) Carefully evaluate alternative management strategies to determine which may be most likely to produce desired results, and 4) Conduct a thorough post-treatment assessment of actual outcomes to see how closely you accomplished (by burning or whatever) what was expected.

    Sorry for the length of this but you obviously struck a chord with me here.

  7. You attended the 2019 Grassland Restoration Network Workshop. You saw Dr. Amy Alstad’s presentation. I don’t remember all of Dr. Alstad’s points, but in simple terms she found fire was very important to maintaining prairie diversity in Wisconsin. Likewise, fire is important to maintaining prairie diversity in Illinois. In Cook County, the best remaining prairies are given priority and burned annually if at all possible.

    The above being said, I wonder if such a high fire frequency would be needed if prairies were large enough that woody species had more difficulty invading. In addition, the introduction of non-native invasive woody species has changed ecosystems in many ways. Non-native woody species are super abundant compared to native woody species. Non-native woody species increase shading, cause mesophication, have allelopathic effects, and in some cases even cause all the topsoil to erode away. All these factors act as a catalyst for the shifting away from prairies and other fire adapted ecosystems. Frequent fire does not completely stop the invasion by non-native species, but it at least keeps the woody invasive species from completely dominating. Frequent fire is used to help keep invasive woody species under control at Nachusa.

    Laura Rericha givens quotes from early settlers regarding the yearly burning of prairies by Native Americans in “Flora of the Chicago Region.” She has some discussion of the subject. Although the primary purpose of her book is recording plant associations including other plants, animals, or fungi.

    If eastern red cedar was your biggest problem, I could see how you could maintain prairie with control efforts and not need to burn. However, when you also have to deal with common buckthorn, glossy buckthorn, several species and hybrids of Asian bush honeysuckles, multiflora rose, autumn olive, Osage orange, black locust, etc. then you will quickly not have a prairie if you are not burning. It is simply impossible to control all the woody species with herbicide over any significant area if they are not being knock back by fire or mowing. The Forest Preserves of Cook County have found prescribed fire to be economical. Unlike mowing, prescribed fire tends to kill at least some of the smaller woody prairie invaders. This saves a lot of time with control efforts.

    In conclusion, the need for using fire to maintain an ecosystem depends largely on where someone is located.

  8. Chris–You wrote, in part:
    “Also, in some prairies where frequent fire is holding back woody encroachment, there are significant concerns about how that fire frequency is negatively impacting populations of plants and animals.”
    What are these significant concerns? I have burned our 40 ac. prairie annually for close to 20 years here in Central IL and am wondering if I should alter my practice.

    • Hi Tom,

      First, I’m not trying to tell you you’re doing something wrong. There are many great examples of annual burning maintaining a diverse plant community while staving off woody encroachment, especially in eastern tallgrass prairies.

      However, there are important tradeoffs too, especially when the whole prairie is being burned each year, and even more so when that prairie is relatively isolated from others. One example is that burning homogenizes habitat structure – all 40 acres of your prairie will be thatch-free, start from short and grow tall, and provide great habitat for animals who appreciate that kind of structure. But it doesn’t do much good for species that rely on litter and standing dead vegetation – including species of small mammals, birds, and invertebrates, among others. It also doesn’t provide habitat for species that rely on short/sparse vegetation structure during the summer months or that thrive best in patchy habitats where there is a combination of short and tall vegetation interspersed throughout the prairie.

      In addition, any burn is going to kill a lot of invertebrates, including those (and there are many) overwintering in that dead vegetation or – for growing season burns – living amongst that vegetation. If the whole prairie is burned every year, you’re essentially causing local extinctions of many of those species – a number of which are unlikely to recolonize, especially if the prairie is isolated from others.

      Again, though, what you’re doing isn’t necessarily wrong. Managing small(ish) prairies like yours comes with a lot of difficult decisions and you have to make the best ones you can. My best advice is to be as clear as you can about your objectives for the prairie. If your 40 acres is an isolated site, you’re pretty limited on the larger vertebrate wildlife species that are likely to have viable populations, no matter how you manage. The same might be true for many invertebrate species too. On the other hand, if your site is isolated, there may not be many other sites those species can survive in the local area, making your site more important for them.

      See what I mean? Difficult choices. That’s why clear objectives are really important. You might very justifiably decide that you’re going to focus on managing for a diverse plant community because that’s what seems most feasible to support at your site. You’d be making some assumptions about the long-term viability of that if the invertebrate community declines in abundance/diversity over time, of course, but as I said above, that might happen despite your best management efforts anyway.

      This is much too complicated to discuss fully in a comment. You might find this earlier blog post helpful too: https://prairieecologist.com/2012/03/05/how-should-we-manage-small-prairies/

      In the end, the best way to ensure that your 40 acre prairie survives, with as many species as possible, into the future is to make it bigger by restoring land around it to prairie. That sounds great, but is rarely logistically or financially feasible. If it’s not, you just have to do the best you can with what you have. Think about what you want from the prairie, do your best to manage for that, and enjoy the results. Good luck!

      • You said “If the whole prairie is burned every year, you’re essentially causing local extinctions of many of those species – a number of which are likely to recolonize, especially if the prairie is isolated from others.”
        But I think you meant to say ‘unlikely’ instead of ‘likely’ didn’t you?

        After 25 years of active management, we no longer burn our 80 acre prairie/savanna even though we have been urged by many within our prairie stewardship network to do so. One reason (other than it is wholly counterproductive because it over-stimulates woody understory) is that we don’t know what we’re burning other than the obvious forbs and woody plants on site; we don’t know what invertebrates live here, and we never will unless a bevy of entomologists take up residence, do an exhaustive multi-year inventory, and advise which of the thousands of species they find benefit from fire or are extinguished by fire. That’s not going to happen.

        So a question: if you do know the botanical composition of a prairie, can you make an accurate inference about the invertebrate composition, and if you can make that inference, can you also know their adaptability and/or risk to fire?

        Thank you for your valuable insight. I look forward to your address at the February 2021 TPE Annual conference in Wisconsin.

  9. Wow, Chris! I agree this will be taken as heretical by some. But I hope your essay starts a vigorous conversation about the questions you raise.
    I will say that here in the humider regions to the east and south of Nebraska, fire appears to be closer to essentil for grassland management … But is it?

      • It’s a matter of scale. Some very small prairies have been maintained without fire by dedicated individuals who treat invading woody species carefully with herbicide. Another refuge for prairie plants that is managed without fire are utility corridors. However, none of these areas are big enough to be habitat for grassland birds. Prairies need to be big to be suitable habitat for all their species. The only way large prairies can be maintained given resources is by using prescribed burning. I apply herbicide to invasive species. It is a tedious process that makes little headway compared to if burning had been done to prevent the invasive species from establishing in the first place.

  10. As someone managing small patches of prairie and oak savanna in northeast WI, this article and sentiment is very helpful. I tend to fall more on the ‘fire is essential’ side. But one of our prairies that was hand planted and has only been mowed for 8 years would be another good example to back up your argument. Very good diversity, very few invasives.

  11. The main goal with annual burning historically (as inherited from Europe) was probably for farmers to maximize the nutritional value of grasslands for the livestock.
    But for the wild ecosystem that’s not the case; a point nobody even thought about back then. Natural grassland was everywhere.

  12. Chris: “However, while it might seem heretical to some, I am not convinced that fire is an essential tool for all prairies. Or at least, I’m not convinced that prairie managers can’t maintain diverse and resilient prairies without the use of prescribed fire. I’d be happy to be proven wrong.”
    ===
    Good for you. We live in an era of when fire, fire, fire is celebrated as the #1 tool and I disagree. I think animals are. I follow ranchers who actually are hands on and do things right. Once animals have made the disturbance and mowed back much of the fuel content, then if fire happens it’s not as severe. But never as the first tool, same for forests or other shrubland habitat. I’m also not a fan of parroting it’s good because the Native Americans did it and they had a mystic knowledge of the land we don’t. They used fire for exploiting the land for it’s resources the same as human beings do today. They also used fire to war against hated enemies. In the old west the earliest Steam Locomotives caused fire, hence those large spark arresters on the stacks. We will never really know for sure without time machine what impace the megafauna had on various landscapes, but we can get a close idea. I’ve pulled away from almost every environmental group who has an intolerance for any type of ranching, even the responsible ones because so much of their stance anymore has to do with political ideology as opposed to the truth. Thanks for posting this.

    • Native Americans historical use of fire is not mysticism. It has been recorded in the journals of numerous settlers and in scars on tree rings. Review “Flora of the Chicago Region” by Laura Rericha for a sampling of settler’s accounts. In recent decades more species have been found to disappear from prairies that are not being burned. Review Dr. Amy Alstad’s paper, “The pace of plant community change is accelerating in remnant prairies.”

      • I would have to say that European immigrants/farmers in the 1800’s and earlier more likely brought with them the old habits from Europe, where the old tradition was to burn annually to improve grasslands. But even so they didn’t use to burn the same patch every year.
        One has to remember that Europe has been burned, grazed and farmed intensively for many thousands of years, and that’s why most of the soils are very poor compared to the American prairies.
        That said, fire during early spring can do a good job at a time when there’s just too much litter to get rid of.

  13. The flip side of this issue is what happens when you may be able to use fire, but grazing is less of an option for various reasons (finding good partner, maintaining fencing, etc). Put another way, if grazing isn’t an option, is fire necessary to maintain prairie?

    • Hiya Patrick,

      It’s a good question to ask. I definitely think fire becomes more important when grazing isn’t feasible or wanted at a site. That’s just math, right? If you have three options (fire, haying, grazing, for example) and then reduce those options to two, each becomes proportionally more important. Whether fire becomes ‘necessary’ at that point, though, is still an open question. Now, if you also remove haying as a viable option (for example, on steep loess hill prairies with scattered tree stumps, etc.) then we’re getting closer to fire becoming ‘necessary’ because there just aren’t that many other ways to remove thatch, fight off woody plants, etc. However, that still doesn’t necessarily mean fire is essential at all sites, especially those with more management options available.

      At least that’s the way I think about it.

      • I always go back to your premise that the goal of management should be to allow every native plant species to complete their life cycle at least once every 2-3 years. Regardless of the management tools used, that should be the goal. So if one only cares about grass, one does not really care about prairie.

        • Patrick, yes, I still think that’s a good rule of thumb. Maybe every 4-5 years. Of course, it’s also important to think about animals in our objectives too, but I think most management that meets the plant-species-life-cycle-rule-of-thumb would be good for animals as well if it’s employed as some kind of shifting mosaic approach.

  14. We know that prairie evolved with and is maintained by three ecological processes: climate, fire, and grazing.

    I think we have to acknowledge the known historical ecological fire regimes (or Fire Return Intervals), which are – very generally – thought to be about 2-5 years in tall grass prairie, ~5-10 years in mixed grass prairie, and much more variable, ~8-25+ years in short grass prairie.

    In my experiences in prairie management (ND and MT), the most important thing for health is the periodic and necessary “defoliation,” which can come in many forms – grazing, fire, haying, etc. It is simply too arid in the Great Pains for plant (grass) leaves to break down on their own – and the resultant litter build up is deadly at some point. So, when it is not conducive to use fire (or grazing), haying will remove that residual vegetation build up of litter – which is critical to prairie health. Very good. I too have seen prairies maintained well with “defoliations” but no fire.

    BUT – I can’t help but wonder what we lose when we don’t have fire on the landscape. I wonder about the nutrient cycling. I know that grazing and burning facilitate two different types of nutrient cycling, but I don’t know enough of the details to understand fully the implications. When we hay and take all of that biomass off-site, I can’t help but wonder on the full effects.

    Makes me think of Leopold’s quote about the fine art of tinkering – “keep all the parts.” When we can, I think we should! Great discussion here, everyone. Do what you can out there!

    “If the land mechanism as a whole is good then every part is good, whether we understand it or not…To keep every cog and wheel is the first precaution of intelligent tinkering.” Aldo Leopold

    • Great points Beth, and I think you’re right about the importance of defoliation and the varied ways we have to provide that.

      Two things:
      First, I actually think we should pay a lot less attention to historic fire return intervals than many people do because I think today’s prairies and their landscape context are so different from those historic landscapes. The way we use fire should be driven by how today’s prairies respond and by what those prairies need for management to keep them diverse and resilient. In some cases, I think that drives people to use fire more frequently because trees aren’t suppressed by the historic fire frequency. Obviously, there can be negative ramifications from that frequent fire use, but it’s also true in many places that a 2-5 year frequency just isn’t going to prevent today’s prairies from being swamped by woody plants. Historic intervals are important to understand as context, but I still think fire frequencies (and all other management treatments) need to be focused on today’s prairies and their issues.

      Second, you’re absolutely right that nutrient cycling and microbial communities and their responses to fire are important and far from well-understood. I think that’s probably the most likely area of study that could push me in the direction of talking about fire as ‘essential’ in all prairies. One thing to think about in terms of haying and burning is that many prairies today are getting essentially fertilized by nitrogen deposition (caused by cars, industrial effluents, livestock confinements, etc.) to the point where many get 10 lbs of nitrogen a year or more, just from the air. Fire and haying both pull nitrogen out of the system, which could actually be helpful in re-balancing nitrogen in prairies. Since higher nitrogen tends to reduce plant diversity by favoring grasses over forbs, that could be really important. It’s not that simple, of course, but it’s fascinating to throw those factors into the thinking about fire and haying, isn’t it?

      Thanks again for your thoughtful comments.

      • My observation from my small sedge meadow garden in my backyard is the portions that I burn has Carex buxbaumii with very green leaves. In contrast, the areas I don’t burn have the typical bluish-green colored leaves of this species. Since leaf color is an indicator of nitrogen content, the C. buxbaumii in the burned areas are likely greener because they have more nitrogen. This could be scientifically measured with a colorimeter.

        A lot of nitrogen released by burning goes into the air. However, some of the nitrogen released goes back into the soil.

        I back burn and keep the fire small. The intensity of the fire must be important in determining whether soil nitrogen increases or decreases after a fire.

  15. I really enjoy reading these comments and this blog. I don’t know the best metaphor to describe the feeling I get when discussions like this come up. Maybe this will work…We are like doctors debating treatments for a patient who is drowning….how do we get rid of that nasty rash, what to do about the hemorrhoids, he should really loose some weight, etc… Don’t get me wrong, these are all things that need attention. The historical tallgrass/mixed grass region has lost 10’s of thousands of acres of grasslands just in the last 10-20 years to row crop conversion…because of economics. The economics have to change or our patient will drown.

    Now…That would be a lively discussion for this blog

    • I can only agree with you. However, there are very few people in this world who can influence the economics, and they’re still mainly going in the wrong direction unfortunately.

      Anyways, if grazing is impossible, a cost effective way of managing grasslands would be to get interested local farmers/ranchers to do the haying – only once during late summer/early autumn of course – so they could use it as winter feed for their livestock.

    • Bob – hard to argue with any of that. The economics are absolutely important. I’d argue, though, that the economics are ultimately driven by values. If we’re going to fix any of this, the real challenge is to get the public at large to care about prairies and conservation enough that they (directly and by influencing policy makers) change priorities. Just because we can make more money off of farming marginally-productive soils doesn’t mean it’s the right thing to do. It happens because there aren’t enough people on the side of prairies when policy decisions are made. It’s hard enough to get people to prioritize forests, which are an easier sell to the public. We’re starting out a little behind with prairies because we first have to show people why prairies are attractive and important and THEN we have to try to convince them to make them a higher priority when we make societal decisions.

      • Thanks Chris. I like your take. Are there any large scale success stories that could be used for reference on how ecosystem revaluation by public/policy makers has changed economics favorably for landowners?

  16. Here is an interesting video on plots that was posted to the Southeastern Grasslands Initiative Ecology, History, Biodiversity Facebook Page.

  17. Wow, this is a cold take!

    Haha I should say I really appreciate this post and the points that are brought up, it’s engaging to think about this stuff, and healthy to challenge assumptions.

    I’ll state at the outset that I agree with Chris: an individual prairie can be fine without fire, and with careful management can achieve all of the goals you have for your plot of land.

    The differences in eastern vs. western prairies are probably central to why I disagree with Chris’s thesis, however. The entire landscape context is much more fragmented in eastern tallgrass praire, preserves are smaller, large contiguous grassland tracts are rare, and seed rain and encroachment from woody species perennially threaten these prairie systems.

    With grazing you may be able to maintain diversity without using fire, but for prairies from roughly eastern Minnesota to the east, grazing is rare.

    The forms of disturbance other than fire have tradeoffs as well. Again, most of this comes down to a difference between eastern and western prairie. For instance, you wouldn’t graze a 1-acre railroad remnant with white lady’s slippers… they would quickly disappear from the site. The stocking rate and size of the preserve are factors that can affect the success of grazing.

    Mowing a prairie can be time consuming. With topography, like the goat/bluff prairies in the Driftless areas of MN, WI, IA, and IL, mowing can be impossible. Mowing can introduce invasive propagules as well. A study in Wisconsin found that replacing hay mowing with fire increased species richness by about 50% and species richness per quadrat doubled:

    https://www.researchgate.net/publication/232679607_Replacing_Hay-mowing_with_Prescribed_Fire_Restores_Species_Diversity_and_Conservation_Value_in_a_Tallgrass_Prairie_Sampled_Thrice_A_59-Year_Study

    Cutting and treating woody encroachment in prairies is time consuming and expensive, at least in eastern tallgrass, and can have off target impacts on vegetation. Depending on the equipment used it can damage the prairie turf and it often requires many years of follow-up.Taking a piece of land in the eastern tallgrass prairie and leaving it unburned quickly and deleteriously invites an insane amount of brush invasion that on just a 40 acre piece of land might be difficult to keep up with annually.

    I might also address what you’re missing with a lack of fire. Without releasing nitrogen due to fires, you may be adversely affecting one of the largest families, fabaceae. Small scale diversity may decrease. And finally, I believe you’re restricting flowering and seed production. In plots that I’ve studied and in other research I’ve seen in eastern tallgrass, flowering production after a burn shows huge increases.Thus, if you’re working with a small and isolated preserve, and never burn it, species may simply blink out from lack of reproductive success.

    Just because you can manage a preserve without fire, doesn’t mean it’s a good idea that you should manage it without fire. Overall, I believe fire is the most economical method for controlling brush invasion and maintaining florisitic quality in eastern prairies. I think it’s a deeply flawed logic to suggest that prairies in general don’t need fire; from Konza, to the Stoddard Plots to Cedar Creek, we see that fire maintains the prairie ecosystem.

    All of this is not to say that everything has to be burned annually, just that I believe going in to a management plan and explicitly excluding fire would seem to be a plan for failure in eastern prairies. I also believe that a lack of prescribed fire on the southern Wisconsin landscape is the single most detrimental thing happening to our natural areas. Florida leads the nation in prescribed burn acreage at 200,000 ac per year, while WI, a similar size, only conducts 40,000 acres of burns each year. A lot of that has to do with available habitat to burn, but in visiting natural areas all over the Midwest, areas with long histories of prescribed fire stand out for their floristic quality and avian richness.

    As a piece of sweeping advice (which I know you weren’t suggesting) I think excluding fire is deeply flawed. Fire may not be a necessary prescription for all prairies, but I believe it’s a necessary prescription for almost all prairies. At least farther east, the tools and time needed to mimic that fire are simply insurmountable.

    I should add that I’m not trying to be critical, this is all great to think about, I’m just pointing out that taking up this viewpoint where I live and work seems problematic and damaging.

    Another component is the invertebrates. From research I’ve seen, it’s usually a mixed bag when it comes to fire and invertebrates. Some populations will decline, but typically won’t go extinct. Other populations recover quickly. For one insect that I keep an eye on, the silphium borer moth–which is evident in June/July when prairie dock leaves brown–I’ve seen no effect of fire on the moths, in fact frequent fire seems better because it stimulates flowering, creates a soil bed for germinating seed, and increases population of the host plant. Could anyone recommend more comprehensive studies on insect populations and fire?

    To answer your question about what’s missing from your family prairie: it’s hard to say until you burn it! Sounds like a fun research project lol. Take quadrat data, insect abundance and richness, and avian abundance and richness, and maybe even small mammal data, and compare it before and after you’ve burned a couple of times. Should take about 8 years and you can get back to us. Easy!

  18. I think a thing missing from this discussion is scale. When talking about individual prairies that are actively managed, I would agree fire is not essential. If you zoom out and talk about thousands of acres across hundreds of different parcels, things change. The labor and time required to hay these or manage the livestock to graze them isn’t feasible. Fire is a powerful management tool and at the landscape scale I do not know of a replacement.

    • Yes, like Chris also has pointed out here, if the only possible option is using fire then obviously that is the best solution.
      However, I personally don’t think it’s good for the ecosystem to burn annually because that’s not a normal occurrence of wildfires.

  19. Another bullet point for the intro – Fire distributes a bit of recalcitrant carbon (char) that can incorporate into the soil over the whole burn. Once charged with fertility elements charcoal is a great soil enhancer.

  20. Chris, you’re a heretic. And proud of it. I’m wondering if your question isn’t a little bit misleading by asking whether or not fire is essential in managing prairies. Fire is simply a part of nature and without prairie fires a part of nature is essentially missing. There are many reasons why a prairie manger may not be able to burn or want to burn. The complex interactions mentioned in many of the replies to your post are all valid concerns. I know you have spent a career working to understand the intricacies of prairies and, yet, even as a whole group we can only understand fragments of these interactions. But, without fire, one aspect of prairies will be missing. Is sacrificing one part of nature necessary to save another? Maybe or maybe not.

  21. Pingback: Fayette Prairie Chapter Library – NPAT

  22. Thank you, Chris for instigating this blog discussion that has spurred such a variety of comments.
    Prairie management is not easy. Every prairie is different, climate is changing, known and different exotic species continue to expand, increases in elements and nutrients from our pollutants affect precipitation, plants, and soils across the landscape, and there is so much more, all making conclusions about our management increasingly more difficult.
    I managed Lostwood National Wildlife Refuge in northwestern North Dakota with prescribed fire and prescribed grazing from 1978 through 2001. During this period and for a few years following my retirement, many scientists studied plant and wildlife responses to these defoliations. Since I retired, I spent 10 years pulling together what we learned. I have tried to summarize this information in a document entitled “A Story of Dedication – Returning the Northern Mixed Grass Prairie to Lostwood”. (It can be downloaded at https://ecos.fws.gov/ServCat/Collection/Profile/1351.)
    Within the document, I have also tried to present the many varying changes that are making prairie management increasingly more difficult, but for sure, without some form of defoliation, native grasslands will die.
    [Smith, K. 2020. A Story of Dedication – Returning the Northern Mixed Grass Prairie to Lostwood. Lostwood National Wildlife Refuge. Region 3 NWRS General Technical Report Series no. 2020(1)]

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