Provenza: Grazing provides benefits, reduces negative impacts from fire events
If livestock can be grazed on rangelands, wildfires are kept to a minimum, are not as devastating and don’t destroy as much habitat and soil life, according to Fred Provenza, a professor emeritus at Utah State University in the Department of Wildland Resources.
Many people today think fire is “natural,” but devastating fires are not natural. Grazing is healthier for the landscape.
“Fire can oxidize a lot of material, and it is wasted, whereas grazing recycles it better,” Provenza says.
Native Americans burned the prairies, and lightning also set some fires, but those prairies were also being grazed with large herds of bison, elk and antelope. There wasn’t always as much fuel load to carry a major fire, he says, and a fire episode was a flash-through that didn’t damage so much.
Fire is the biggest problem in areas that are not grazed enough. If there is too much fuel load, fires are often hotter fire that destroy plant roots and seed bank and damage the top layers of soil. Then, there will be nothing but opportunistic invasive weeds coming back in because the perennial grasses, forbs and shrubs are gone.
This is one reason we now have so much cheatgrass across the western U.S., and a sagebrush-fire or cheatgrass-fire cycle exacerbates the problem, he says.
“Fire can be very damaging, especially in a low rainfall area,” adds Richard Teague, Texas A&M AgriLife Research rangeland ecology and management scientist. “In the area of Texas where I am, we get an average of 22 inches of precipitation annually. I’ve asked the question, when a region burns, how long does it take for essential ecosystem functions like infiltration, nutrient status and carbon status to recover after a fire?”
Teague’s research has shown it takes three average or better-than-average-rainfall years for rangelands to recover. However, it takes eight years to get three average rainfall years.
“So, it takes longer than people realize for the land to recover,” he says.
Fire can have a negative impact on the ecosystem for a long time, especially if it burned hot enough to destroy plants, root systems, seed bank, the top layers of soil and its microbes.
“A fire can cause ecosystem degradation since it removes vegetation that protects the soil from exposure to sun, raindrop action and overland water flow, which increases soil erosion and damages soil biological function until plant cover is restored. Good grazing management is need after burning, to speed recovery,” says Teague.
Ideally, producers strive for less bare ground and higher soil organic matter, and fire can be counterproductive.
In one of his studies, Teague looked at the amount of bare ground in various range areas, because this is a well-documented way to assess erosion hazard, which increases if there is insufficient plant cover to dissipate the energy of raindrops before they strike the soil.
Previous research on rangelands around the world indicates that bare ground has considerably lower infiltration and higher runoff and erosion than ground covered by perennial grasses.
Transition to grazing
“Timing is everything on burning. Deseret Land and Livestock used to do a little burning to reduce sagebrush in some areas, but it was in the early spring, when weather was still cool and there was still some snow and the fire didn’t get out of hand,” Provenza explains. “We started working with them and showed how they could reduce sagebrush with grazing rather than fire.”
He continues, “We showed that not only could we reduce the abundance of sagebrush with fall and winter grazing – and make it just part of the mix, along with grasses and forbs – but we could also improve the range.”
“Grazing was just as effective as the herbicides and fires in reducing sagebrush and not as damaging because fire and herbicides destroy some of the things we want to keep,” Provenza adds. “Grazing does the job and provides additional benefits, supplying urine and feces for better soil fertility.”
“This also benefited the livestock by providing winter range and a forage source,” he says.
Grazing works very well in some cases, Provenza explains, using the example of an Oregon rancher who spent his life attempting to eliminate sagebrush using burning and herbicides.
“He said he never thought about grazing the sagebrush areas or feeding some of his cattle on that ground during winter,” Provenza says. “The hay provided the supplement to help the cattle utilize the sagebrush and added manure. It worked terrifically well. The sagebrush became a winter forage and the cattle helped rejuvenate those landscapes without fire.”
Grazing has worked well on a lot of sagebrush country over the years.
“Even some of the ranges down in central Utah that looked like there wasn’t much there saw benefits when sagebrush came back to greater biodiversity with winter grazing. If we knocked the sagebrush back by grazing and gave the other perennials a chance, they came back strongly,” Provenza comments. “I was amazed.”
“When we were grazing sagebrush with cattle and sheep, we were able to allow perennial plants to thrive and expand again,” he says.
“Timing is important. Winter is the best time to graze sagebrush because it’s not as nasty. The terpene compounds that make sagebrush less palatable for livestock are lower in late fall and winter,” Provenza explains. “Grazing can be the best tool to enhance biodiversity and keep the ecosystem in balance.”
Heather Smith Thomas is a correspondent for the Wyoming Livestock Roundup. Send comments on this article to firstname.lastname@example.org.