VALE – When a fire scorches a large swath of rangeland it not only impacts cattle but demolishes an unseen ecosystem that allows wildlife to thrive.
A range fire disrupts a carefully-balanced structure of plants and sagebrush that benefits everything from snakes and bats to sage grouse to deer and pronghorn antelope.
“It’s a very rich wildlife community out there hidden from the human eye,” said Christian Hagen, an associate professor at the College of Agriculture Sciences at Oregon State University.
That balance has been upset across huge swaths of Malheur County range damaged by megafires.
Sagebrush is especially key in that ecosystem as it provides forage and cover for animals.
“Healthy sagebrush is home to mule deer, pronghorn, a whole suite of reptiles and amphibians in riparian areas. We can’t forget about the predators out there – mountain lions, bobcats, badgers, weasels,” said Hagen.
All of those animals, plant species and sagebrush are “pretty tremendously” dependent on each other, said Hagen.
“You have animals tied to a certain plant species. Then you have your usual interrelation between predator and prey species,” said Hagen.
A range fire delivers a series of blows to wildlife, some immediate while other impacts are not evident for months.
“The most immediate thing is mortality. Some individuals can’t make it out and they die,” said Rachel Germain, an assistant professor in the Department of Zoology at the University of British Columbia.
She is an expert regarding evolutionary ecology and how different species interact with each other.
Germain said in an interview that over the next couple months, animals on the range “don’t have any food.”
“So, they have a starvation response and a lower body mass,” she said.
Many wildlife species are “creatures of habit” and return to a burned area after the fire is out, said Hagen. Yet they do not find the ecosystem they expected. Instead their habitat is gone and with it, food.
“What we’ve seen with sage grouse, even after a massive fire, they came back because that is all they know but it literally costs them their lives,” he said.
Hagen said mule deer and pronghorn also return to burned areas they once roamed.
“That’s because they are trying to eke out a living and ultimately they will figure out there is no food and we got to go,” he said.
Fire isn’t a new phenomenon to rangeland, said Hagen.
Fire is factored into the rangeland ecosystem, an important part of its evolution and structure.
“There is no doubt that fire, prior to European and Eurasian settlement, and even in early European settlement, was a natural driver of change in the desert,” he said.
What’s changed, he said, is the frequency and intensity of those range fires.
“So, it doesn’t allow the natural system to reboot. Recovery from fire, just naturally speaking, is a very slow process and if you increase the frequency of fire it makes it more difficult for the system to recover,” he said.
One result of such intense fires is the encroachment of invasive grass species like cheatgrass and Medusahead, said Hagen.
“Cheatgrass gets into the understory which is just a tinderbox of fuel,” he said.
The understory is a layer of vegetation or shrubs like sagebrush and other grasses such as western wheatgrass or wildrye.
When a fire burns through an area, invasive weeds can return and outcompete native vegetation, such as sagebrush. That can turn burned areas into “a biological desert,” said Hagen.
“If we are looking at a fire like Cow Valley, what will it come back as is healthy sagebrush or if there are enough invasive species it will transition into a whole new ecological state that won’t serve anything,” said Hagen.
Hagen said he’s seen rangeland burned by a big fire respond both ways.
Recently, Hagen and other scientists finished a 12-year study of the impact of the Holloway Fire on sage grouse. That blaze consumed more than 500 square miles of rangeland in Oregon and Nevada in 2012.
Hagen said some areas of the burn zone on the Holloway Fire became a biological desert where the sagebrush will never return.
“You move up in elevation, the cheatgrass has a little harder time competing and native grasses tend to recover better so there are places on the mountains where you can’t tell if there was ever a fire,” he said.
Yet there are large strips of land on the high desert where invasive grasses rule.
“They (sections of land) are likely going to be lost without intervention to try to transition out of this invasive grass system,” said Hagen.
Tucker Freeman, a district wildlife biologist for the Ontario office of the Oregon Department of Fish and Wildlife, said the range ecosystem is more susceptible to “(fire) starts and more prone to intense fires that consume and essentially eliminate habitat for a long period of time.”
Tucker also said invasive weed species play a role in fire intensity.
“Where you have large scale effects where you lose large swaths of habitat it is replaced by invasive species and it burns fast and carries that fire into the brush,” he said.
Freeman said the long-term question for wildlife habitat in a fire zone is “how bad was the burn?”
“Especially here, they need that sagebrush component because they need the cover and the food component,” he said.
He said for the long-term most big game species won’t return in large numbers to scorched range unless there is some sort of landscape restoration.
Freeman said it can take up to 40 years for mature sagebrush to return to a burned area of range.
“That’s part of the problem we are facing. Sagebrush is such an integral part of the Great Basin ecosystem,” he said.
Freeman said there are no plans to restrict hunting locally because of the fires.
“We’re not going to see a large decrease in the numbers out of a unit per se where it will affect tag numbers,” he said.
News tip? Contact reporter Pat Caldwell at [email protected]
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