In 2017, massive wildfires roared over the southern Great Plains, scorching more than 750,000 acres in Kansas, Oklahoma, and Texas. Though wildfires are a natural part of life on the Great Plains, more than a century of fire suppression has set the stage for catastrophic wildfires that have caused unprecedented losses to human life, property, livestock, and wildlife in recent years. How can we effectively reduce wildfire risk? New research shows that by pairing prescribed fire with grazing, range managers significantly reduce wildfire fuels.
The fire-grazing treatment—known as pyric herbivory, or, more commonly, patch-burning—also produces the mosaic of diverse grassland habitat that’s just right for lesser prairie-chickens and other grassland-dependent wildlife.
On the Great Plains, wildfires are three times more frequent and four times bigger than they were thirty years ago. Some of the biggest increases in both size and frequency have occurred in the southern Great Plains. That’s an immense problem for both people and wildlife.
Led by Dr. Dwayne Elmore of Oklahoma State University, the research team studied the effects of management that used prescribed fire alone (no grazing) versus management that used a combination of fire and grazing known as pyric herbivory, or patch-burn grazing.
What is patch-burning?
Patch-burning mimics the natural duo of forces—fire and grazing—that together shaped prairie-habitat for thousands of years. Ignited by lightning and by native tribes, fire killed encroaching woody plants and prompted the vigorous re-sprouting and germination of native prairie vegetation. This succulent new growth, high in protein-rich forbs, attracted herds of large herbivores, which intensively grazed the recently burned area. The resulting habitat was a mosaic of newly burned areas scattered among grassland patches of varied ages since burning.
Ranchers mimic this process by burning portions of a pasture each year. Livestock are naturally drawn to focus grazing on the tender new growth.
This dynamic tag-team of patchy fire and grazing yields far-reaching benefits to the land—improved soil health and nutrient cycling, increased native plant and wildlife diversity, reduced invasive plants, reduced fuels for wildfire, increased drought resilience, and increased carbon sequestration.
These changes, in turn, yield greater production of higher quality forage for livestock. Previous studies have already shown that patch burning increases overall biodiversity, and that diverse vegetation within a pasture produces greater stability in annual weight gain for cattle.
Why is patch-burning good for prairie-chickens? They need the kind of structurally diverse grassland habitat that patchy fire followed by grazing produces. Lesser prairie-chickens use areas with low-growing vegetation for lekking, tall and dense vegetation for nesting cover, and moderate height vegetation with lots of protein-packed invertebrates (which are known to increase in diversity and abundance following fire) for brooding rearing.
To both benefit prairie-chickens and reduce fire danger, management practices must promote structural diversity and reduce fire behavior characteristics—namely flame length and rate of spread.
What the research found
The research team’s study shows that prescribed fire alone has limited utility in reducing fuel build-up, since the plant biomass quickly rebuilds in the absence of grazing. On its own, prescribed fire would need to be performed annually to keep the fuel load down. That fire frequency would reduce biodiversity, creating a uniform grassland landscape that lacks the kind of structural and species diversity that lesser prairie-chickens and other prairie wildlife need.
The team found that patch-burn grazing, however, significantly reduced flame lengths and rates of fire spread for an extended period of time. Moreover, subtle changes in weather from day to night—like reduced wind speed and increased fuel moisture—created more significant reductions in flame heights in patch-burned treatments.
The study showed that sites treated with a combination of fire and grazing achieved greater fuels reduction than fire-only sites. Moreover, sites treated with both fire and grazing created the vegetative structure and species mix that best suit prairie-chickens.
The take-home for management? Don’t defer grazing on burned areas. As the study puts it, “We add to the evidence that deferment of grazing after fire is not warranted, at least in highly productive rangelands, such as those found in the southern Great Plains.”
“Given the reductions in rates of fire spread, we suggest pyric herbivory [patch-burning] could, if implemented at a landscape scale, result in lower area burned by wildfires in the southern Great Plains.”
That’s mighty welcome news in a fire-prone landscape.
Research and the Lesser Prairie-Chicken Initiative
The Lesser Prairie-Chicken Initiative, led by the USDA’s Natural Resources Conservation Service, helped fund this research. That’s because research studies like this one help ensure that we’re encouraging the right actions in the right places to benefit prairie-chickens. That way, we can strategically direct funds to the places and practices that will yield the greatest conservation return on investment.
The Lesser Prairie-Chicken Initiative is a partnership-based, science-driven effort that uses voluntary incentives to proactively conserve America’s western rangelands, wildlife, and rural way of life.