Tag Archives: prescribed fire

A Long-Awaited Fire

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This week, about 22 people from a variety of organizations gathered to conduct a prescribed fire at The Niobrara Valley Preserve. The 900 acre burn unit was on the north side of the Niobrara River. Before a big wildfire in the summer of 2012, the area was covered with mixed-grass and tallgrass prairie, bur oak savanna, and ponderosa pine/eastern redcedar savanna/woodland.

That wildfire swept across more then 70,000 acres, including more than 30,000 acres of the Preserve. North of the river, it wiped out the vast majority of the ponderosa pine and eastern redcedar trees and top-killed many of the bur oaks, though the oaks resprouted from their bases. Where the pines and cedars had been, smooth sumac quickly filled in, spreading quickly across much of the area and forming large clones that now cover hundreds of acres (and are still spreading).

Remember to click on photos to see bigger/sharper versions. If you’re reading this in your email, you’ll have to click on the post’s title to open it online so you can click photos.

Here’s a photo of part of the area we burned this week, taken back in September of this year. You can see the red sumac clones, the green bur oaks, and the white skeletons of pine and cedar trees. The Niobrara River is just out of frame to the right.

This area has been the subject of countless hours of discussion about how we should guide it into its next ecological phase. We could just let the sumac spread unimpeded, creating a huge shrubland. Unfortunately, eastern redcedars are reinvading that area too. Letting sumac spread ahead of that invasion would suppress grass growth, and without grass we’d be unable able to use prescribed fire to control the cedars. Since we know dense stands of eastern redcedar provide poor habitat for wildlife and suppress the diversity of plants and other species, we want to avoid that.

We’d be glad to have some ponderosa pines come back, but they are notoriously slow to re-seed themselves after a ‘stand-replacing fire’, especially when there aren’t mature trees around to drop pine cones. We can plant some (and the Nebraska Forest Service has already planted a fair number for us on the steeper slopes), but any fire hot enough to kill young eastern redcedars would kill pines too, unless we plant them in steep rocky areas where there’s insufficient grass to carry fire. Of course, those are the same places where it’s difficult for trees to establish because the ground, such as it is, is dry and hard.

The consensus reached among stewardship staff was that we needed to get a fire through the area, both to remove a lot of the downed wood (making it easier to access the area) and to kill the numerous invading cedar trees. It would be nice not to kill the small pines, but controlling the cedar invasion is a bigger priority right now. One fire won’t suppress the sumac much, but staff might be able to mow or otherwise treat those sumac stems in the year following the fire to amplify the suppression effect.

Deciding to burn the area was relatively easy compared to the task of figuring out the logistics and prepping the site. Firebreak routes had to be found on the steep slopes between the flat above the ridge and the river below. Huge numbers of dead pine and cedar skeletons – some standing, some on the ground – had to be cleared away from those firebreaks to give us a chance to control the fire along those boundaries. Chad Bladow, fire manager and burn boss for the fire, had to figure out how to get crews, water, and vehicles into places where the terrain made that difficult.

Eventually, though, everything came together and we assembled this week to make it happen. My role was pretty small. I showed up and did as I was told. The crew at the Niobrara Valley Preserve had already put in tremendous effort getting the site ready, coordinating the crew and their needs, working with local fire departments to get permission and support, and doing all the little things that go into making a big event happen.

We started the burn on the big flat above the ridge, where we could use trucks to lay down a wet line ahead of igniters.
Here, we’re widening the backing fire (on the downwind edge of the unit) to make it wide enough to stop any fire coming at the line later in the day.

We had help from some nearby ranchers, Nebraska Game and Parks Commission, Northern Prairies Land Trust, Central Platte Natural Resources District, the Bureau of Indian Affairs Pine Ridge Agency, and others. There was a lot of expertise and experience among crew members, as well as some people who were still relatively new to prescribed fire. Even for many of us with quite a bit of experience, this would be a more complex burn than we’re used to. Fortunately, Chad Bladow and several others on the crew were very capable leaders, and the fire was pulled off smoothly and effectively.

We started by burning a big flat area above the ridge, but the line I was on quickly started working down some very steep slopes, igniting as we went. Getting water to those slopes so we could control the fire took a lot of planning and equipment. A big tank was set up above the ridge and a very long hose was connected to it and stretched downslope. A pump charged up the hose with water so the crew could spray the edges of the firebreak and keep the fire contained.

The east boundary had some very steep areas, where we couldn’t use any vehicles. The crew set up a ‘hose lay’ – a long stretch of fire hose stretching down the slope (right/dark yellow) with multiple smaller hoses (left/pale yellow) that fed off the main. A gas-powered pump pulled water from a big tank and into the hoses, which crews used to control the fire as we ignited down the slope.
Former Hubbard Fellow (and current Nebraska Game and Parks Commission employee) Chelsea Forehead was part of the crew. Here she’s igniting down one of the steep slopes.

Once our crew made it off the steeper slopes and down to the relatively flat areas at the bottom, everything moved much more quickly. We ignited all the way down to the river, which then acted as the south boundary for the fire. Meanwhile, the other half of the crew worked west along the top and then came down the slopes on the west side until they also hooked into the river. From there, it was a matter of lighting off everything in the interior before it got dark and temperatures dropped and relative humidity rose.

Here’s an aerial view (via drone) at about 2pm, after the perimeter was blacked-out on the east half of the unit and much of the interior had been ignited to allow fire to spread.

That interior ignition was partially accomplished by people with drop torches – directed by others who stood on vantage points and guided them down the slopes via radio directions. Additional ignition, especially in really steep areas, was done with a specialized flare gun. Even with all that effort, the difficult terrain and the short period of daylight at this time of year meant that the sun went down before everything could be ignited. (A subset of the crew went out the following day and lit off the remainder.)

Here’s Chelsea again, lighting a flat area near the river.
This drone photo shows the crew moving west (into the wind) and igniting the lower parts of the slopes and the area between the river (center) and the road (out of frame to the right).
The fire should top-kill these sumac stems, but they’ll grow back quickly unless we follow up with mowing or some other treatment next season.
Here’s a drone shot showing the east half of the unit shortly after a line of fire (to the left) was ignited and starting spreading to the northeast, pushed by the wind.

As the sun went down, many of us had little to do besides watch the fire spread across the interior of the site and patrol the outer edges. With permission, I grabbed my camera and took advantage of the late day light and smoke to get some ‘mood shots’.

A smoky scene with a tree in the foreground and sumac and other shrubs behind it.
I thought these three looked like they were walking away from the final scene of an action movie.
As sunset approached, the fire started to spread more slowly and some of the crew gathered along the road.
Crew silhouettes in the smoke.
Waiting for everything to burn.
More sunset smoke.

I also did some (relatively) close-up photography of small patches of fire. I love the way flames look when captured in still photos.

Close-up fire portrait.
Another fire portrait.
and another.
Bur oak leaves burning.

As darkness settled in, the remnants of the fire kept burning. We knew the bigger logs and standing dead trees would burn through the night, but we had wide bands of blackened ground around the perimeter to contain the fire. The overnight forecast was also favorable, with high humidity and temperatures well below freezing, which would keep the fire from spreading. After assuring the perimeter was secure, the crew retreated to the Preserve headquarters just across the river to watch from there while putting away equipment, grabbing some food, and reviewing the day’s events.

As darkness set in, I got this drone photo of the river and part of the fire. For those of you who know the area, the Preserve Headquarters are just to the right of the scene and the Norden Chute is just out of the bottom of the frame. (Click to see a better version of the image.)
I took this photo from across the river well after dark. You can just see a few stars above the big tree.

Ecologically speaking, the 900 acres we burned this week is a very small portion of the 56,000 acre Niobrara Valley Preserve, and neighboring properties contain similar habitat that stretches in all directions for miles. We’re hoping to learn what we can from this fire and any follow-up treatments so we can apply that to other areas of the Preserve. More importantly, we hope our experiences will be helpful to our neighbors, who are dealing with very similar issues in terms of sumac expansion, eastern redcedar invasion, and slow recruitment of ponderosa pine.

If you’re interested, you can look back at some of my old blog posts to see what this site looked like immediately after the wildfire and during the next couple of years. The grasslands on Conservancy land and neighboring properties bounced back from the summer wildfire quickly, as grasslands do. The woodland and savanna areas, though, were a bigger question mark for us because there is less collective wisdom about how those kind of sites respond to a big fire like that.

Since summer wildfires in sites invaded by eastern redcedar are becoming more common, we all need to work together to figure out what kind of land stewardship is most helpful after an area burns. Hopefully, this week’s fire and its impacts will be educational for us and others. In the meantime, it sure felt good to be able to pull off a burn we’ve been talking about for a very long time.

On behalf of all our staff at the Niobrara Valley Preserve – thank you to everyone who helped with the fire this week!

What’s the Best Burn Schedule for Prairies?

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Fire has been part of prairie ecosystems for as long as prairies have existed.  In many parts of North America, prairies both came into existence and then persisted because of intentional and thoughtful application of fire by Native peoples.  Forces such as drought and lightning, intertwined with human management, have helped maintain prairie habitat for millennia.  Fire, people, and prairies are inextricably linked.

Great!  So how often should I burn my prairie?  And what time of year should I burn it?

Ok, hang on. 

While those questions are reasonable in the right context, they’re almost useless on their own.  You’d never ask an experienced baker, “hey – how much flour should I use and when do I add it?”  The obvious response would be, “I don’t know, what are you trying to make?”

Prairie burns should be conducted for specific reasons, not just because the calendar says it’s time to burn.

There is no set recipe for good prairie management.  If prairies are anything, they are dynamic.  That dynamism necessitates an adaptive approach to management.  Burning, like all other management treatments, should be part of that approach.  Every fire should be planned and conducted on its own merits, not as part of a pre-planned schedule.

Weather fluctuations, alone, can strongly influence the growth and flowering of plants.  Insect populations are directly tied to weather as well, but also linked to what happens to plants.  Because so many other species eat, or are eaten by insects, anything that affects them ripples through the entire ecosystem. 

The fickleness of the weather can make a prairie act very differently from one year to another.  On top of that, the behaviors of invasive species, disease organisms, herbivores, pollinators, predators, and other members of prairie communities are also driven by complex, interconnected, and unpredictable forces.  It’s a big, glorious mess.

As a result, the answer to how a prairie should be burned depends on lots of factors. What is your overall objective for your prairie management?  What has the weather been doing?  How did prairie communities respond to recent management treatments (fire or otherwise)?  What are the significant invasive species threats and what influences their ability to become dominant?

This site was burned to control eastern redcedar trees. The timing of the burn was aimed at creating enough localized heat to kill the target trees.

Even bakers don’t always follow a fixed recipe.  Based on how the dough is shaping up, they might add a little extra flour – or not.  Factors like humidity and altitude cause ingredients to act and interact differently and it’s not always possible to accurately predict those responses.  As a result, bakers are constantly testing, learning, and adapting. 

Prairie management has to be even more flexible and adaptive than baking.  Knowing what the average historic fire frequency was in your area is instructive, but it shouldn’t necessarily dictate how often you burn your prairie.  You should be burning when/if it will help you achieve your broader objectives, and if your recent observations show that it would be helpful.

Scientists and historians have estimated historic fire frequencies for most prairie regions.  That’s interesting information, but remember that those are based on long-term averages, which smooth over a lot of variation.  You can be sure the people setting fires centuries ago weren’t gridding out the landscape and deciding when to burn a patch based solely on a regimented schedule.  They burned when it made sense for their objectives, which means some areas surely burned more frequently than others.  Lightning fires, too, would have ignited on irregular schedules, driven by the capriciousness of forces like thunderstorms, drought cycles and grazing.

Historic fire frequencies are mathematic syntheses of irregular events, they’re not instruction manuals.  At their best, they can help us understand the kind of world prairies evolved in.  That’s definitely useful, but the world is significantly different than it used to be, so what might have been appropriate in the past might not always apply today.  Use history as context, not as a template to be blindly followed.

There is much discussion about how common summer fires were in historical prairies. That’s an interesting conversation, but it’s even more important to evaluate what the impacts of summer fires are today and how they might (or might not) achieve local objectives.

Similarly, the optimal seasonal timing for a burn should be based on what you want to accomplish with that particular treatment.  What timing will make the most sense for your objectives?  What are the potential negative consequences of that timing?  The predominant season of fires hundreds of years ago helped shape today’s prairies, but – just as with fire frequencies – that history shouldn’t be the only guide to what we do now. 

With regard to both the seasonal timing and frequency of fires, it can also be important not to get locked into a rigid pattern.  Every fire has both positive and negative consequences.  If you always burn at the same time of year, the same species will always be negatively impacted, and that will surely include some species you don’t want to suppress.  Mixing up the seasonality of burns now and then can help ensure you don’t drive any species to local extinction.

Burning on the same schedule over many years in a row can also cause problems.  Regardless of what frequency you choose, there will be some species that thrive in that regime and others that don’t.  If you don’t ever vary the pattern, you risk losing the species that aren’t suited to it.

Most importantly, be sure there are adequate unburned refuges available any time you burn so you don’t eradicate whole populations of animals (especially invertebrates).  Again, every fire has negative consequences, no matter the timing.  Populations of some species will likely be wiped out, or nearly so, within the burn footprint. 

This beetle was fortunate to find a mini refuge within this fire and will probably survive, but many of its peers might not have been so lucky.

In landscapes with lots of prairie, affected species can probably recolonize from nearby unburned areas – though that process may take more than a year or two.  That recolonization works much less well in fragmented landscapes.  If you burn the only 40 acres of prairie within miles, populations of animals that perish in the fire are unlikely to re-establish.  Even if there is other grassland habitat around, you might have invertebrates in your prairie that are tied to plant species not present in those neighboring habitats.  That will put those invertebrates at risk of local extinction if a burn snuffs out their entire population.

This summer burn covered only a portion of the management unit and there is a lot of other prairie habitat nearby to supply recolonizers from any species negatively impacted by the fire.

Prescribed fire is a powerful force in prairies.  Every fire has both positive and negative consequences, driven by the timing and frequency (as well as its intensity) of its application.  Prescribed burning should be used as part of an adaptive management approach.  Every management treatment (fire, grazing, mowing, herbicide application, etc.) should be applied when it will help achieve objectives and in response to observation and evaluation of what’s happening on site.  After all, smart bakers and prairie managers both know it’s risky to rely too much on a set recipe. 

You might say they both knead to be adaptable and roll with the punches. 

…Or you might not. You might not say that at all.

Hey!  Some of you might remember Evan Barrientos from when he was a Hubbard Fellow about six years ago.  Evan’s doing great work these days as a conservation photographer, videographer, and storyteller.  His latest personal project is called Fireforest.  It’s a terrific examination of the role of fire in Colorado forests – I encourage you to check it out!