Patches of Fire and Habitat

It’s been a difficult year for conducting prescribed fires so far – the wind seems to be blowing even harder and more consistently than in recent memory.  And that’s saying something, living in the Great Plains.

A couple of weeks ago, we were able to pull off one prairie management burn here in the Platte River Prairies.  The fire went well, and this week I took a quick walk through the burned area to see how the regrowth of vegetation was coming along.  It’s been a cold and dry spring, following a dry fall and winter, so plant growth has been slow, but things are finally starting to kick in.  Within the burned area, many plant species are a little behind their compatriots growing outside the burned area, but others are ahead.  Those that are behind are the species that were already starting to grow when the fire came through – those species had to start again, so are behind schedule.  The species that are further ahead in the burned area are those that are taking advantage of the warmer soil and have either germinated or emerged faster than those in the cooler soil of unburned areas.

Regrowth in sand prairie burned a couple weeks ago.  The wildflower in the foreground is shell-leaf penstemon (Penstemon grandflorus).

Regrowth in sand prairie burned a couple weeks ago. The wildflower in the foreground is shell-leaf penstemon (Penstemon grandflorus).

Regardless, plants are growing well in the burned area.  That’s good, because cattle will arrive within the next week or so, and we want the burned area to be particularly attractive to those grazers.  One of the major objectives of our fire was to concentrate grazing in one portion (the burned patch) of the prairie this season, leaving the remainder of the pasture with much less intensive grazing.  Hopefully, the result will support our efforts to create a variety of habitat patches across our prairies, and to shift the location of those patches from place to place each year.

The patch we burned this spring has had no fire and very little grazing over the last couple of years.  Last year, it had tall vegetation and abundant thatch – conditions that favor a certain set of plants and animals, but not others.  This year, it will have very little thatch and the vegetation will be short in stature because of season-long intensive grazing.  Next year, it will begin a multiple season recovery period from that fire and grazing until it is burned again sometime down the road.  (You can read more about patch-burn grazing here.)

Burning a different patch of prairie each year helps ensure that a mixture of habitat types is always available and most or all wildlife and invertebrate species can find the habitat they need.  Our prairies usually have a patch of very short habitat, several patches in some stage of recovery from intensive grazing, and some areas that are tall and very lightly grazed – or ungrazed.  Some animals will follow those habitat patches across the landscape.  Others will go through boom and bust periods within one portion of a prairie, depending upon what conditions they thrive best under.

Because we’re always changing the location of habitat patches, plant species also experience changing conditions from year to year.  This means that some species flourish one year, but may have to wait a few years before those favored conditions return.  In the meantime, other plant species will find success.  Constantly changing conditions help ensure that no group of species becomes too dominant, but that all species can survive and maintain a place in the plant community.  Our long-term data has shown the our plant communities have stable to increasing plant diversity under this kind of management, and we’re not seeing any plant species disappear.

This burned patch makes up between a third and a fourth of a 110 acre management unit in our Platte River Prairies.  Burning only a portion of each unit each year helps ensure good wildlife habitat and changing growth conditions for plants, but also helps avoid catastrophic impacts on species vulnerable to fire.

This burned patch makes up between a third and a fourth of a 110 acre management unit in our Platte River Prairies. Burning only a portion of each unit each year helps ensure good wildlife habitat and changing growth conditions for plants, but also helps avoid catastrophic impacts on species vulnerable to fire.

Another benefit of burning only a portion of our prairies each year is that it helps us avoid catastrophic impacts on plant and animal species that are negatively impacted by fire.  Invertebrates that overwinter above ground, for example, can be destroyed by an early season fire.  Growing season fires can kill animals (invertebrates and vertebrates) that are unable to escape by leaving the area or retreating underground.  These kinds of impacts are somewhat unavoidable, regardless of the season of fire, but by burning only a portion of our prairies, we can try to restrict impacts to a relatively small proportion of the population of each species, allowing the majority of individuals to survive and recolonize the burned patch over time.  Burning an entire prairie, especially in highly fragmented landscapes in which recolonization is unlikely, can result in completely and permanently obliterating vulnerable species from a site.

Hopefully, the wind will pause a few times during the remainder of the spring, and we’ll create a few more burned patches in our prairies.  If not, we’ll try to create patches of short habitat by haying or by temporarily fencing cattle into an area to knock vegetation height down.  We’ve found that all three methods (burning, haying, temporary enclosures) can create a patch that attracts livestock grazing afterward - and therefore pulls that grazing off of other portions of prairie.  There are lots of ways to create patchy habitats, and none are necessarily best.  As long as there is always a mixture of habitat types across our sites, we feel pretty good about our management.

Hopefully, the species living in our prairies feel pretty good about that management too.

 

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About Chris Helzer

Chris Helzer is an ecologist and Eastern Nebraska Program Director for The Nature Conservancy. He supervises the management and restoration of approximately 4,000 acres of land in central and eastern Nebraska - primarily along the central Platte River. Chris is also the author of "The Ecology and Management of Prairies in the Central United States", published by the University of Iowa Press.
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11 Responses to Patches of Fire and Habitat

  1. Keith Long says:

    I like patch burning too, but really like enclosing the cows (or steers) in a small temporary fence and force them to eat and stomp old forage into the ground. You get most of the benefits of burning plus you get the manure from the cows, and, unlike burning, the ground stays covered so erosion is reduced. The only drawback is that you don’t burn up the woodies, which is why I still burn at times.

  2. Steve Clubine says:

    High stock density can do good things but, as you noted, Keith, it won’t kill woodies like cedar. That takes fire and if don’t realized that, cedars will soon overwhelm you.

    Great post, Chris.

  3. Laura Hubers says:

    Chris – we are planning a patch burn graze on an 1100 ac native tallgrass prairie site that will be divided into 6 patches (120-150 ac in size) and I’m having trouble figuring out a stocking rate and length of graze. I see you graze all season, others have suggested a light stocking rate and grazing only until July. Any words of wisdom?

    • Chris Helzer says:

      Laura – there is no easy right answer to your questions. It all depends upon objectives and the conditions at the particular site. I’d be happy to brainstorm with you about this if you like. Send me an email with the particulars if you’re interested in talking more about it. chelzer@tnc.org

    • Rex Peterson says:

      I recommend you also visit with your local university extension agent who can get you in touch with a range ecologist familiar with your prairie.

  4. James McGee says:

    In the eastern tall grass region we often get enough snow to flatten the thatch. The deer can be really hard on the cedars in areas with higher deer populations. I think the bigger problem for eastern tall grass prairies is gray dogwood. Even with heavy deer browse the dogwood will take over a restoration area unless it receives regular burns. Fires also help knock back invasive woody species like buckthorn and Asian honeysuckles which can be more easily herbicided right after resprouting.

    This was another good post Chris. It is very timely considering I just found my first casualty of this spring’s burn season while planting plugs yesterday. The garter snake must not have been able to find a hole fast enough. Maybe our restorations need some of those “darn gophers.” :)

  5. Pingback: Patches of Fire and Habitat | Gaia Gazette

  6. Gisela Fisher says:

    So interesting, Chris. I really enjoy reading your posts. Thanks for writing them.

  7. Suzanne Smith says:

    Chris,

    I live in East-Central IL but want to let you know I so enjoy reading your blog and have a learned a GREAT DEAL from your posts (and had a few good laughs, too). Thank you!

    Not sure if you have time to respond to inquiries, but I have a small ~1/4 acre prairie restoration going on that was burned for the first time this spring. This is an irregular piece of farmland that was taken out of production 5 years ago now. I know that is not much compared to your projects but with your experience I thought I would ask your help.

    My problem is that there is brome grass along two roadside edges of this parcel that has been intruding into the prairie area and it seems to be taking over. We are in the tallgrass prairie region but it is a rather dry patch so I am attempting to establish little bluestem and a variety of forbs but big bluestem and now Indian grass are also growing here. The Indian grass especially will take over if I do not keep it in check. Argh! Any suggestions? Is there any hope of establishing some sort of balance?

    Thanks. Sue

    • James McGee says:

      Chris seems to be busy so I will try to answer your question. Indian grass tends to invade quickly but gets out competed over time. Other grasses like big bluestem and switch grass can be much more dominating in restoration settings. Smooth brome is commonly planted in pastures. Smooth brome tends to thin with repeated prescribe burns giving way to better adapted prairie species. A quarter acre is a rather small planting. You should be able to handle weed control on such a small site if you put the effort into it. In contrast, removing weeds from 1000 acres is much more difficult task.

    • Chris Helzer says:

      Sue – so sorry to have missed your larger message. When I read it initially, I only saw your first couple of sentences. Balancing cool-season grass dominance vs. warm-season grass dominance is doable. What’s trickier is managing so that neither warm-season or cool-season grasses become so dominant that they outcompete all your forbs. Mowing or burning when right before grass flowers is often the most effective way to reduce its vigor and tip the balance away from it. Unfortunately, if you really do have both brome and indiangrass trying to become dominant, weakening one might just allow the other one to gain ground – and, again, forbs still lose.

      One suggestion might be to use early spring or late fall herbicide (Roundup) treatments to eliminate most of the smooth brome. If this is a restored prairie, it likely doesn’t have a lot of forbs or native grasses/sedges that are actively growing in the very early spring or very late fall? If that’s the case, herbicide treatment at that time of year might not have much of an impact on species other than brome. If you could knock brome out of the way (mostly), then you could concentrate on indiangrass. Trying some periodic summer mowing treatments in the areas where indiangrass looks like it’s becoming dominant might knock it back and allow some other plants a chance. I would try not to mow the entire patch every summer, unless it looks really necessary, but rather work the spots that need it each year. If brome starts coming back, you might be able to get away with just spot spraying it as it tries to creep back in.

      It’s not an easy task, and will likely take some adaptive management as you try various ideas, but those are some thoughts to help you get started. Good luck! Let me know how it goes.

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