Cheatgrass, an invasive annual grass that has spread to Nevada rangelands, is largely to blame for the Intermountain West’s rising wildfire risk. But researchers at the University of Nevada, Reno have found that by using targeted cow grazing during the dormant growing season and luring the cattle with stations carrying protein feed additives, fire hazards can be decreased.
“Our work establishes that protein feed supplements in the fall and early winter can attract cattle to locations dominated by cheatgrass, significantly reducing the standing fine-fuel biomass by more than 50%, while making room for native grasses to grow,” Barry Perryman, professor of rangeland sciences at the University of Nevada, Reno said. “This research builds and affirms other studies that show dormant season grazing helps control the dominance of cheatgrass,”
Invasive annual grasses have been and will continue to be one of the most ecological concerns to the ecosystems of the Intermountain West. At regional spatial scales, the non-native cheatgrass (Bromus tectorum L.) is the most troublesome invasive annual grass.
Cheatgrass is the ecologically dominating plant on more than 20% of the sagebrush steppe, and it is thought to cover 11,000 square miles of the Great Basin.
According to a study published in Elsevier’s journal Rangeland Ecology and Management, strategic supplementation offers a useful technique to target cattle grazing at certain regions within cheatgrass-invaded systems to lessen fine fuel deposition during the dormant season.
“It is difficult to concentrate animals in one place during spring for long enough periods of time to be of any use,” Perryman said. “However, cattle can be concentrated on cheatgrass during the fall, using supplementation as a tool. Reducing the amount of cheatgrass fuel carryover may effectively reduce the amount of total fuel available during the next year’s fire season. If several hundred pounds per acre of cheatgrass can be removed during the fall, through cattle grazing, that is several hundred pounds that will not be added to the next year’s fuel load.”
Land managers have choices to reduce fine fuels at specific, manager-defined locations by managing supplement station placements and cattle grazing distribution close to or bordering regions with significant ecological value or social importance.
It is difficult to concentrate animals in one place during spring for long enough periods of time to be of any use. However, cattle can be concentrated on cheatgrass during the fall, using supplementation as a tool. Reducing the amount of cheatgrass fuel carryover may effectively reduce the amount of total fuel available during the next year’s fire season. If several hundred pounds per acre of cheatgrass can be removed during the fall, through cattle grazing, that is several hundred pounds that will not be added to the next year’s fuel load.
Professor Barry Perryman
Strategically positioned supplements can lower the expense of building fence infrastructure, prevent interactions between wildlife and fences, and provide managers more freedom to move management sites in response to changes in precipitation, the availability of cheatgrass biomass, and management objectives.
In October and November from 2014 to 2017, Perryman and the scientific team employed liquid protein supplements at a production-scale working ranch with a herd size that varied from 650 to 1,200 head of cattle.
After farming was abandoned there in the late 1970s, the study pasture was a mix of rangeland and defunct farmland that had been badly overrun by cheatgrass. Cheatgrass predominated the vegetation on the site, and greasewood and cheatgrass coexisted in some sections.
Cheatgrass consumption ranged from 48% to 81% when the cattle grazed along the transect line of the supplemental feeding stations, with no variations found between the supplement stations that were closest to and farthest from the water.
“While more research is needed to fully understand the extent of how far protein supplements can successfully attract cattle away from water in large pastures, our research indicates this distance can be up to two and a half miles on relatively flat cheatgrass-invaded areas during fall and early winter in northern Nevada,” Perryman said.
Fall cow grazing is a logistically practical method to lower the amount of carryover fine fuels in big pastures in the case of near monocultures of cheatgrass.
“With strategic placement of supplements, we can direct this grazing to effectively create a linear fuel break,” Perryman said. “Cheatgrass can provide an important forage resource for cattle in much of the Great Basin and Intermountain West during the dormant season, and this can help during the fire season.”
The authors conclude that flexible grazing management options will make it easier to use targeted grazing fuel reduction projects on rangelands in the Intermountain West at advantageous times, like fall or winter, and will give more opportunities to better match livestock production and vegetation management objectives in a “win-win” situation within annual grass-invaded systems.
In previous research, a carefully controlled, small-scale targeted spring grazing project discovered that a reduction of 80% to 90% in above-ground biomass decreased flame length and the rate at which fires spread the following October.
Another study found that winter grazing reduced biomass by 40% to 60% on sagebrush and native perennial grass plant communities, which in turn reduced flame height, rate of spread, and area burned in comparison to an ungrazed control area.
In southeast Oregon, Perryman and colleagues are working on two sizable demonstration projects, and in the Vale District of Oregon, a related study is being conducted without any additional funding. Additionally, the research revealed advantages for cattle ranchers and a recovery of native grasses.
“Every operation is different,” Perryman said about ranchers adopting the idea. “It will benefit some and be of no utility for others. It has saved significant hay costs in our eastern Oregon demonstration projects.”
It seems that native grasses are able to repopulate the regions where cheatgrass has been reduced, whether by seeding or naturally, according to Perryman, who is also a member of the University’s Experiment Station.
“There was a major seeding effort on the study sight in 2018-19 by the operator (it was located on private land),” Perryman said. “In some instances areas may be seeded, while in other instances there are enough existing perennial grasses to respond. There are some published studies now showing increases in perennial grasses after about four to six years. Kirk Davies, a co-author of this study, has led that research.”
