A Successful Prescribed Burn Depends on Details

By Gary DiGiuseppe

While fire is a good tool to manage invasive species and restore grass vigor, a burn has to be prescribed to maximize benefits and minimize any environmental losses. It’s fire, and if it escapes the burn unit, there can be losses.

“There are things that you learn when you’re doing this,” says Bowie rancher and conservation activist J.K. “Rooter” Brite. “Most of them are learned the hard way. You made a mistake, you failed to anticipate something was going to take place, and you realize what you have to do in the future to mitigate that risk. You have to have your fire crew very well briefed as to what their responsibility is, and whoever the fire boss is has to keep a constant vigil.
It all starts with the burn unit, the defined area to be exposed to the prescribed fire. Jeff Goodwin, state rangeland management specialist for USDA’s Natural Resources Conservation Service (NRCS), says, “We try to use any and all natural barriers that we can use within a pasture, burn unit or ranch.” That could be a crop field, a creek, a river, or even a county road — any natural or manmade structure that can minimize the amount of fireguard that has to be established.



Types of fireguards
The most common fireguard, he says, is a bladed, 15-foot mineral soil fireguard all the way around. But mineral fireguards in areas like Brite’s, which are highly erosive or have rocky soils, are discouraged and ineffective. “We don’t get a good break,” Goodwin explains. “Sometimes we’ll have skips or grass bridges across the fireguard, and that can lead to escapes.”
Brite solves the problem with black lines, although they’re more time consuming. “We’ll go in several weeks ahead of the fire and mow in a couple of strips on the edge of where we’re going to burn,” he says.
“We’ll skip out 5 to 6 feet between the strips, so we have 2 6-foot wide areas cut down as short as we can cut it, about 2 to 3 inches. We’ll leave a 6- to 8-foot wide area in between that we can light.”
To achieve the best control, Brite accomplishes these burns under less than optimal conditions, with higher humidity and little wind. As a result, the stubble is left a little higher than it would be otherwise. “When you start your backfire on the day of the fire, you have to watch this stubble,” Brite says. “It still has the potential to have a very low fire move across it. Since you’re doing the backfire, you have to have a follow-up truck to make sure that you don’t have an encroachment across the fire line.”
Brite will also use wet lines; a technique Goodwin says is used often and is not destructive to the environment. It can be water, or water with retardant. “Once we’ve laid down a wet line, we light a back fire off of that line into the wind to create a blackline, this process effectively creates a blackened area on the downwind sides to assist in stopping the prescribed head fire,” he says.
“The down side of a wet line is that it takes a lot more time and a lot more people to accomplish, because you don’t have that safety barrier of the 15 feet of bare ground. You are working off wet grass (fuel). Safety and attentiveness are critical when working with wet lines.”
There also have to be crewmembers with suppression equipment putting out the back fire as you go. But, Goodwin says, “There are producers who don’t want mineral fireguards at all, and in those cases we can use a combination of wet lines and natural barriers to create a burn unit. It’s more difficult, but it can be done.”
Another option, although it’s not used very often, is a green fireguard — nothing but growing plants. Goodwin doesn’t like them because, he says, “I don’t like having fuel in my fireguard, green or not.”
The fireguard stands in contrast to the burn unit itself, which contains the dry and desiccated plants of last year. “You would want to shred around the inside of the fireguard,” he says, “giving a little bit of a break in fuel, and then we can work off of that green line because the green material is not going to burn, so when it gets there it’s going to go out.” It also, obviously, has to be established well in advance.
Does prescribed fire lead to erosion?
For the most part, Goodwin says prescribed fires do not contribute to erosion — in fact, he says, “In my 16 years of burning, I have never seen a gully formed or any kind of erosive response because we burned a pasture.”
That’s because recovery is rapid — the tops of the plants are gone but the roots remain in the ground, and at most times of the year the pasture is green again within a couple of weeks. “It’s not fully grown back, but it’s grown back to the point where we’re not going to have any issues with overland flow or sheet erosion,” he says.
If you burn in December, of course, the window for green-up is somewhat longer. “Basically, the response revolves around soil moisture before and after the burn. Having adequate soil moisture before the burn will generally ensure adequate forage response depending on the timing of the burn,” Goodwin says. “Post-burn moisture is just as important to recovery times, especially when burning during the growing season.” Which makes the task that much more difficult for Frank Price. “It’s just really hard to get done on a regular basis,” says the Sterling City rancher.
“We’ve tried to burn 4 pastures in a year in different grazing units — I tried for 6 one year — but 3 is the most we ever got burned. Everybody talks about how successful the burns are, and how you ought to get into a regular burning cycle on all the rangeland.
I came to the realization that is never going to happen, at least in the environment that my son and I work within, because with so many different climatic factors to work with, you have to have the fuel load for the fire and the proper conditions as far as rainfall, wind conditions and humidity.”
Price, who with his son Sims won the National Cattlemen’s Foundation Environmental Stewardship Award in 2013, says the key to the operation is the way they graze their livestock. “It’s a single herd program, where we’re using traditional pastures and work those cattle as the same herd through those existing pastures,” he says. “It’s worked very well for us as far as leaving the rangeland more sustainable than we had in the past. We’ve even reached the point where we do not feed our mature cattle in the wintertime because of the improved grazing conditions. It’s been very productive for us.”
Post-fire grazing
The cattle play a big role in Price’s burn programs. Pastures targeted for a burn are grazed very lightly, or not at all, to build the fuel load. “Recently, I was going through a pasture that we burned last August and was trying to determine if we’re going to graze it this spring or not, because we had very limited rainfall this winter,” he said. “We’re going to do what we call a ‘flash graze’ this spring and graze it very lightly, and then move on.”
Whether or not you’re conducting prescribed burns, Price believes the animal impact on the land is very important. “The ‘trampling and grazing effect’ during grazing stimulates the grasses,” he says, “and it is a very good tool in preparing for a burn, and of course, you have to be very careful after burning. A lot of folks make the mistake of putting too much livestock back in it too quickly after a wildfire or prescribed burn, thus not allowing the grass plants adequate time to recover and that’s not good for the grass. It’s all a judgment call that the range manager has to make with every burn. That includes planning pre-burn and post-burn. Just because the fire is out does not mean you are finished with the prescribed burn.”
Price started conducting prescribed burns in the 1980s. Sims is a state-Certified Burn Manager. “It’s an excellent tool,” Frank says, but the region’s habitual dryness makes it that much harder to plan and complete a good burn.
He has used assistance from USDA’s Environmental Quality Incentives Program (EQIP) to clear a 500-foot side strip from the north and east sides of burn pastures. Then, they use black lines to reduce the risk of fire escape during the burn.
“We haven’t had a fire get away from us,” he says, but adds that they have come close. “One of the biggest problems with burning is putting the labor force together, and getting all of the climatic conditions on that day of the burn to actually get it done,” Price notes. “You can wear out a lot of people just trying to get the fire completed safely.” That, he says, is where the pre-cleared 500-foot strips pay off.
He says a lot of their perennial grasses still have not recovered from the wildfire that came through on April 15, 2011. It was followed by 100 consecutive days of 100-plus degree temperatures with no rainfall.
“That ground was scorched bare and literally baked, and soil temperatures a foot below the surface reached 140+ degrees,” he says. “Some said that the soil was ‘cooked’ to the point that it would be sterile, but it is recovering very well in some places — with the help of tender loving care from our grazing program.”
Price says they prefer to work with fire under their terms — prescribed burns — but benefits can even be found from a wildfire. In 2011, they got some very good control of cedar and prickly pear, and even had the “opportunity” to rebuild some fences in places to enhance their grazing program.
“All of the major resource areas in Texas evolved under some sort of a fire regime,” says Goodwin. “We’ve taken that fire dependence out of a lot of our plant communities, and they have evolved into a fire-independent state, such as cedar breaks. Any time we can get some sort of fire back on the landscape, it’s going to be one of our most economical practices to slow down woody brush encroachment. From a standpoint of ecological significance, it also can be one of the most effective, depending on the target species. Most of the time, it provides positive responses at the end of the day.”
“All you’re doing with fire on brush is suppression,” Brite points out. “It’s not elimination. It’s just management and, in a sense, it is the same way with decadent growth on grass. Every few years, depending on how you’ve managed that range, it can need a fire to run across it to get optimum performance out of it.”
Price offers an anecdote on the healing properties of fire. During his first burn, he says, “There was a motor grader that we used to blade the fire guards. It was parked in the area we were going to burn. We couldn’t get it started, so we just took the drip torches and burned around the outside of that motor grader. The buffalo grass where the motor grader was sitting did not burn. For 2 years after the burn, the buffalo grass was taller and more vigorous where we burned than where that motor grader was sitting. That was very telling as to what fire can do.” -TC