The Mullen fire tore through 175,000 acres, the largest wildfire in Wyoming in recent history. Photo: Zach Alexander

CASPER, Wyo. (AP) — The morning of Sept. 17, as Scott Butler clambered over fallen log after fallen log and around dead trees as far as he could see, he thought about how only a fire could create the renewal long needed.

The Savage Run Wilderness, nestled in the southern end of the Snowy Range, had been ravaged for years by the mountain pine beetle. Like most of the range, it was covered in more dead trees than live ones.

And now, more than a month after the Mullen Fire tore through more than 175,000 acres of mountainside and destroyed dozens of homes and buildings, wildlife biologists, hunters and other forest users are beginning to think about that transition from beetle kill to wildfire. If there is a silver lining to the largest wildfire in Wyoming’s recent history, it’s the eventual benefit for wildlife, they say.

“It really pushed a reset button for the entire forest,” said Ryan Amundson, terrestrial habitat biologist for the Wyoming Game and Fish Department. “If we could have done it on our terms, I would like to see 170,000 acres burned over 20 years, not all at once, but we have places to look to like the Yellowstone fires of ’88 where there is a tremendous response. It will come back.”

Even as destructive as fires have become in a changing climate — burning entire communities on the West coast and blanketing states with apocalyptic orange smoke — wildlife biologists remind people that fire is also still a natural part of our forest’s process, the Casper Star-Tribune reported.

“The wildfire will create a flush of new life, a reset and rebirthing,” said Jesse McCarty, Laramie Ranger district wildlife biologist for the Medicine Bow-Routt National Forest.

Burning what’s already dead

Mountain pine beetles are endemic to the Rocky Mountains, but by the late ’90s, drought and warming temperatures combined to produce a perfect storm for the tiny beetle. The insects bore into trees – largely lodgepole pine in southeast Wyoming – and feed. Some trees can naturally kick the insects out if there aren’t too many. Most trees eventually die.

The result by the early 2010s was over 100 million acres in the Rocky Mountains of dead lodgepole pines turning from green to red to brown to gray.

A couple of fires whipped through since then. The Squirrel Creek Fire in 2012 burned about 10,600 acres and in 2018, the Badger Creek Fire consumed more than 20,000 acres.

But most of the forest remained untouched as standing dead trees prevented sunlight from reaching and growing anything new underneath, Amundson said.

In the past decade, many of those dead trees began falling, allowing for some new growth underneath. But the process to turn over an entire forest like that would be “painfully slow,” Amundson said.

“With fire you get more rapid decomposition and release of nutrients into the soil.”

Much of the area burned by the Mullen Fire, including the Savage Run and Platte River wildernesses, is under part of the Medicine Bow National Forest’s recent landscape vegetation analysis. The plan was “developed to respond to unprecedented landscape-level tree mortality from bark beetles and other forest health issues,” and called for nearly 300,000 acres of management including clear-cutting, prescribed fires, and hand thinning.

But logging came with its own problems as more trees fell across the forest, Amundson said. And even the most ambitious plans can still create what forestry officials call an “ice cream patch” where new growth is limited to patches and wildlife eat most of the new growth before it can be established.

A large fire like the Mullen Fire will, in some ways, wipe the slate clean, allowing aspens, lodgepole pines, grasses, shrubs, and wildflowers to flourish. How long that takes, and if invasive species can be kept at bay, is a bit more complicated.

Winners and losers

McCarty is quick to ask people not to place value judgments on fire. It’s neither good nor bad.

“There are winners and losers,” he said. “Ultimately this will reset succession. Those early succession species will survive and late succession species will decline.”

McCarty lost five buildings on his property to a wildfire once. He knows the devastation they can cause. But for wildlife, he points to the benefit to the Snowy Range’s elk, mule deer, and bighorn sheep herds, said Amundson.

Fewer than 100 bighorn sheep live in the Douglas Creek herd, and have been constricted in the last few decades by dense trees, Amundson said. Bighorn sheep need wide, open areas near cliffs to use their vision as a primary means of defense. Game and Fish biologists have collared some of the sheep in the herd, so will be able to track them as they move into newly burned areas.

For elk and mule deer, the benefit will be less about tree cover and more about a sudden abundance of food.

When a fire burns, it clears out conifers like lodgepole pines. The aftermath is twofold. First, aspen trees reappear. Aspens require much less water than conifers because they’re typically smaller and are dormant for half the year. That means more water on the ground for grasses, wildflowers, and wildlife. Aspens also grow quickly, sometimes reaching 2 or 3 feet tall mere months after a spring fire. And to elk and deer, aspen may as well be candy, but the nutritious kind.

All that water also acts as a natural fire break in the event of another fire, Amundson said.

Fire, ironically, also benefits lodgepole pines. Lodgepole pine cones are serotinous, which means they’re sealed with wax that only open and release seeds with high heat. The cones can open occasionally with direct sunlight, but they generally require fire for distribution.

“Can you have too much of a good thing? Yeah. We wouldn’t want to see the entire mountain range go up,” Amundson said. “Deer and elk are on the forest a portion of the year but still have intact winter ranges they’re going to.”

But for other species like some amphibians and fish requiring clean water, excess nitrogen and phosphorous run off could prove detrimental, McCarty said. Some bird species including goshawks that require high forest canopies and brown creepers, which scoot up large trees and eat bugs, will likely decrease, at least in the short term.

Biologists are also worried about invasive species that can take advantage of newly-burned soil, particularly cheatgrass.

Exactly how plants regrow may depend on the fire’s severity. The hotter the fire the longer it will take for regeneration, said both Amundson and McCarty.

“Things die in wildfires, but it’s also a reset button,” McCarty said. “With beetle kill, it could be a good reset.”