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TWIN FALLS — When it comes to greater sage grouse management, grazing often has a bad rap. But the two greatest threats to the iconic bird’s survival are wildfire and invasive species, and grazing can help reduce both hazards.

“Grazing has always been a part of a sagebrush ecosystem,” said Karen Launchbaugh, a University of Idaho range ecology professor. She’s been studying the effects of grazing on the sagebrush ecosystem including fire management and sage grouse nesting for many years.

Cows have a role in both fire management and invasive species control, two separate but interwoven issues. Since the 1980s, the number of fires in southern Idaho has decreased but the size and intensity of those fires has increased. Interestingly, the number of livestock on Idaho rangeland has also decreased over that time.

Cheatgrass and medusa grass are both excellent fuel sources that are easy to ignite. Both grasses are winter annuals that start growing early in the season and then dry up early, which extends the fire season.

“We’re finding that if we don’t graze, cheatgrass will come,” she said during a UI range management seminar held earlier in the winter.

But studies have shown that moderate grazing, especially early spring grazing when the cheatgrass is bolting, can significantly reduce cheatgrass populations compared to pastures that have not been grazed. A study in California showed that early grazing can reduce cheatgrass and increase perennial grasses by eight times.

The trick is to graze off the cheatgrass early and then remove cattle to give the perennial grasses time to flower. It’s not a quick fix. Even if cattle remove all of this year’s seed heads, seed that dropped in the past can remain viable for three to five years.

Winter grazing can also be highly effective at controlling cheatgrass by removing the duff from the soil surface. Cheatgrass is an annual so it must sprout each year from seed. Removing the duff, removes that nice warm bed from above the seed which reduces germination.

“Grazing can reduce fire intensity and increase range recovery,” Launchbaugh said. “We won’t stop a fire with grazing but we can reduce the intensity and size.”

She points to the Murphy Complex fire ten years ago as an example. The fire was roaring along but stopped when it reached pastures that had been grazed.

“We can handle a fire in the ecosystem if it is mild and patchy,” she said.

Grazing within an ecosystem can create that patchiness that slows the fire and helps fire fighters control it. But grazing can also reduce flame length, which helps keep the fire fighters themselves safe. At 50 percent utilization, the old maxim of graze half and leave half, flame length can be reduced by 39 percent.

Launchbaugh is about halfway through a long-term study to evaluate the effects of grazing on sage grouse using five sites across southern Idaho. Researchers are evaluating four different grazing systems including spring grazing on alternate years, no grazing, and both spring and fall grazing. Birds have been collared so they can be followed.

Nesting success and hen weights has fluctuated from year to year but grass height seems to be a factor in nest success. Grass height is about 12 percent higher at hatched nests than unsuccessful nests.

Cattle tend to graze between shrubs leaving taller grass under sagebrush where nests are typically found. She’s measured 14 different species of grass and found all species were greater than 7 inches tall even when grazed. The most common grass species in southern Idaho is Sandberg bluegrass, which sage grouse don’t seek out.

Launchbaugh is also evaluating how grazing impacts insect populations since insects are an important food source for chicks. Sweep net and trap counts have shown rested pastures have less insect biomass than grazed pastures. Ants are one of the most important insects for sage grouse chicks and she’s seen a 32 percent increase in ant biomass in grazed pastures.

It’s still too early in the study to know for sure what’s going on, but it could be that grazed pastures have more succulent plant growth that insects prefer. Or that targeted grazing has increased the population of preferred perennial species.

Cattle have had a role in the sagebrush ecosystem for more than 100 years. Whether that role is good or bad often depends on how and when an area is grazed, Launchbaugh said.

“It’s all in the skill of the manager.”

“Grazing can reduce fire intensity and increase range recovery. We won’t stop a fire with grazing but we can reduce the intensity and size.” Karen Launchbaugh, University of Idaho range ecology professor

“Grazing can reduce fire intensity and increase range recovery. We won’t stop a fire with grazing but we can reduce the intensity and size.” Karen Launchbaugh, University of Idaho range ecology professor
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