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Western Innovator: Researcher establishes grazing as fire tool

Ungrazed areas had larger, hotter fires, more damage to native plants.

By Brad Carlson

Published on October 4, 2018 9:41AM

Kirk Davies, lead rangeland scientist for the USDA Agricultural Research Service, in Burns, Ore.

Kirk Davies, lead rangeland scientist for the USDA Agricultural Research Service, in Burns, Ore.

Courtesy USDA ARS, Burns, Ore.
Fire in an ungrazed sagebrush community.

Courtesy USDA ARS, Burns, Ore. Fire in an ungrazed sagebrush community.

Capital Press

Kirk Davies and his fellow rangeland scientists in southeastern Oregon for years produced studies showing earlier grazing reduces future fire risk while benefiting native plants.

Now they are working to figure out how to apply these lessons on the larger scale that the vast sagebrush steppe landscape often demands.

“With these findings established, now the challenge becomes prioritizing where to apply this in land management,” said Davies, lead rangeland scientist with USDA Agricultural Research Service in Burns, Ore.

Issues inherent in working on the usually large-scale range include coordinating and moving people, equipment and cattle; a limited number of cattle available; and some public opposition to public-lands grazing altogether, let alone as a management tool, he said.

“We are hoping to work with more landscape ecologists, looking at how it applies across the landscape,” Davies said. That would include investigating, long-term, how rangeland plant communities respond to fire whether they are grazed or not, and deriving a grazing approach to suit a location’s unique fire risk — deciding how much to graze and in which season, for example.

The U.S. Bureau of Land Management Burns District has used targeted grazing to help reduce fine fuels, particularly annual grasses, District Manager Jeff Rose said. The effort is on a fairly small scale now, but the district is working with ARS to help scale it to a level that will be effective in larger landscapes, he said.

Fires haven’t yet materialized on treated, grazed, areas and it’s hard to predict where a fire will start, Rose said. “There is a lot of anecdotal evidence that it will work,” he said.

Davies and colleagues conducted research for years before publishing a 2009 paper documenting that grazing can help native plants.

“We saw that long-term ungrazed areas, when they were burned, were subsequently invaded by exotic annual grasses,” he said. “We found moderately grazed areas recovered to the native plant community. They didn’t have that invasion and were much better off.”

The 2009 study’s text said in part that even plant communities that aren’t accumulating fire fuels beyond historical levels may need low-severity, fuel-reducing disturbances to improve resilience to more severe disturbances.

Researchers in turn began looking into fire severity.

In ungrazed areas, “we found we had larger and hotter fires, and those fires caused higher mortality of desired native annual bunch grasses,” Davies said. “We also found ungrazed areas were much more likely to ignite with an ignition source and more likely to spread …with higher flame heights and faster-moving fire.”

Even areas that went ungrazed for just one or two years were found to have greater fire risk, he said. Moreover, grazing in the fall or spring ahead of peak summer fire season greatly reduced the risk of severe fire.

Findings from the researchers’ 2010 study included that moderate grazing reduces wildfire risk by decreasing fine fuels available for ignition, and limiting spread by reducing fuel continuity, the text said in part. While moderate grazing makes prescribed burning more difficult, it can help produce a mosaic burn effect that can reduce a fire’s speed and overall size.

Their other studies found that dormant-season grazing increased moisture levels to an extent that an area was at risk of fire some two months later into the summer season; and that winter grazing can reduce wildfire size, intensity and spread in shrub areas (both 2015); prefire grazing increases post-fire resistance to exotic annual grass invasion and dominance for decades (2016); and fall and spring grazing — especially spring — decreased ignition probability and a fire’s ability to spread by increasing fine-fuel moisture while decreasing fuel mass and height (2017).

“Essentially we are looking at the effects of grazing on fire risk, behavior and severity, and even post-fire recovery,” Davies said.

He researches rangeland comprehensively, from plants, soils, grazing and fire to weeds, encroaching vegetation — like Western Juniper — and various environmental conditions.

Name: Kirk Davies

Title: Lead rangeland scientist, USDA Agricultural Research Service, Burns, Ore.

Age: 40

Hometown: Princeton, Ore.

Education: Ph.D., rangeland ecology, Oregon State University; dual B.S., rangeland resources, crop & soil science, OSU.

Family: Wife and three children


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