The Bob Marshall Wilderness Complex is a great place to hunt, fish and hike for many folks. It’s also a great place to do science. University of Montana professor Andrew J. Larson has been studying the cycles of wildfire in the Bob’s South Fork for years now.
The Bob is a great place to study wildfire because the Forest Service today primarily lets fires in the wilderness burn. But that wasn’t always the case. At the turn of the 20th century and earlier, the West saw some huge fires, including an active fire year in 1889 and the notable 1910 fire, to name a few.
In 1905 the Forest Service was founded and fire was enemy No. 1.
The following is an excerpt from the “Use Book” of 1905, by Forest Service Chief Gifford Pinchot.
“The injury to all persons and industries which results from the destruction of forests by fire and careless use is a matter of history in older countries, and has long been the cause of anxiety and loss in the United States. The protection of forest resources still existing is a matter of urgent local and national importance,” he wrote.
But Forest managers in the era like Elers Koch fought blaze after blaze, only to lose. Koch openly questioned suppressing all fires and the millions, even back then, that it cost to battle them.
But Koch lost the argument and by the 1930s, the Service created the 10 a.m. policy, which meant that as many resources as possible would be used to put out any wildfire by 10 a.m.
So for decades, the Bob didn’t see hardly any large fires and certainly nothing on the scale of the thousands of acres that burn today. The reasons were twofold — people put them out and in the ‘40s, ‘50s, and ‘60s, it was generally cooler and wetter on average, Larson noted.
But the Wilderness Act was passed in 1964 and managers began to argue that fighting the fires was contrary to the act itself, that fire suppression was an imprint of man on the landscape.
On Aug. 17, 1972 a lightning-caused fire in the Selway-Bitterroot was allowed to burn as part of the “White Cap Study.” The fire didn’t amount to much, but it marked a seachange in the way wildfires in the wilderness were managed.
Today, Adams, uses the Bob as a classroom and a research landscape. He’s studied fires from multiple aspects, but perhaps most fascinating is the research of areas that have burned twice or more in the past 34 years.
There are some places in the South Fork alone that have burned over as many as four times. Each fire changes the landscape.
From 2005-2014, the South Fork saw substantial areas of reburn. The fires also reshape the woods themselves. Species like Douglas fir and spruce don’t generally survive a fire. Spruce have thin bark and fir, while they have thicker bark, will often succumb to beetle infestations after a blaze. Larch are the hardiest, by far.
The second burn, when it comes through, acts as a fuels reduction treatment, cleaning up the understory, burning the downed and dead logs and adding another important element to the soils — charcoal. Charcoal can last for hundreds of years in the dirt and helps make it more fertile.
Places that have burned three, even four times have far fewer trees and more brush and grass, as one might expect. But they’re generally not devoid of trees, Larson noted.
“The Bob wants to be a forest,” Larson said.
Under the right conditions, secondary fires can create idyllic savanna-like woods, with large trees and a grassy groundcover — groves of old larch and ponderosa pine are coveted camping areas in the Bob.
Having said that, a real hot fire will kill everything, Larson cautioned.
If one views a fire history map of the wilderness, it’s literally covered with the scars of fire. Still, there are groves of old growth that have withstood the test of time. Some larch in the Bob are more than 700 years old, living in places where even the most intense fires generally don’t reach.
Left alone, fires with mixed severity also result in a more complex woods. Larson has also compared natural fire to prescribed treatments. He found that natural wildfires had eight to 10 times more regeneration than prescribed treatments.
The prescribed burns, he found, generally didn’t burn hot enough, though he noted that land managers over the years have been tweaking the methods to get better results.
One thing is for certain. The woods in the wilderness will continue to burn. The summers continue to get hotter and drier. And the Bob, untrammeled by man, will continue to evolve.