The Big Burn and the Mid-Seral Bulge

By Ryan Haugo, forest ecologist 

and Jon Schwedler, associate director,conservation programs

Earlier this winter PBS ran a documentary based on Timothy Egan’s bestselling book “The Big Burn”, the story of the massive wildfires of 1910 that reshaped many forests across north Idaho and western Montana.  With current snowpack at or near record low levels across much of the Northwest, many people are already worried about our forests and the upcoming fire season.  As we think ahead to this summer, it’s a good time to revisit the lessons of the original Big Burn. 

As part of the roll-out of the PBS documentary Ryan Haugo was interviewed by Jon Schwedler with the Conservancy’s Restoring America’s Forests team about the lasting impacts of the Big Burn on our forests today and our current forest conservation efforts. 

Ryan Haugo © Rheta Rabe

Following are excerpts from Still Feeling the Big Burn, by Jon Schwedler

It might seem like the Big Burn is interesting history, but not really relevant for forest management today. And nothing could be further from the truth. To understand why, you need to know a perhaps funny-sounding term: mid-seral bulge.

For those of us of a certain age, that phrase may prompt a self-conscious gaze down to our mid-sections. But in truth, the term is not about waistlines, although it does have an interesting parallel to those among us who are Baby Boomers.

Mid-seral bulge is actually a scientific term foresters and scientists use in describing a preponderance of middle-aged forests across large portions of forested land. This condition can result in a uniformity of habitat that poses problems for wildlife trying to make a home in that forest, as they often rely on more than one age group of trees for food and shelter. Unfortunately, many of our nation’s forests, particularly in the West, are in a state of mid-seral bulge.

 

Understanding the Bulge

The “bulge” specifically refers to the spike observed when same-age trees are plotted on a graph. Just as a graph plotting the ages of the U.S. population would reveal a bulge reflecting the Baby Boomers, so too a mid-seral bulge reveals a spike in a number of same-age trees within a forest.

At 36 years old and a lean 6’1”, The Nature Conservancy of Idaho’s forest ecologist Ryan Haugo can’t shed much light about waistline bulges or Baby Boomers, but he can describe how mid-seral bulges came about in the U.S. Northern Rockies, and what The Nature Conservancy is doing to address them.

“First, it’s important for us to remember there is no one ‘perfect’ stage of natural forest— forests everywhere are in a constant state of transition due to fire, storms, and insect infestation, and wildlife and plants have evolved to take advantage of the different habitats created by those forces,” Ryan explains.“Our forests in the Northern Rockies have especially been shaped by natural fires, which historically created a diverse mosaic of tree ages, heights, and densities within individual forests.” 

Meadow Creek © Bill Mullins

But Ryan points to a seminal event in the history of north Idaho and western Montana that put in motion the causes of today’s glut of same-age trees in his region— the Big Burn of 1910. That year a huge series of fires hit the communities and forests of the region like a fiery sledgehammer.“The fires of 1910 were tragic, with 78 people dying in those fires, and several towns burned,” Ryan says. “On the forest side, millions of acres were scorched.” Across thousands of mountainous square miles in the Northern Rockies a new generation of trees sprouted to life following the fires, the seedlings of today’s mid-seral bulge.

After the Burn

Consequences large and small of the Big Burn spread beyond the region, too. In Washington, D.C., the shock over loss of life spurred the empowerment of the newly-created federal agency, the U.S. Forest Service we know today.  However, Ryan says, many of the lessons were more of a mixed bag.“Because the Big Burn was so tragic, as a nation we started to think that fire was purely a bad thing, and we needed to put out all forest fires whenever they occurred,” he says. “The result of that approach, though, has been a long steady build-up of woody fuels in our forests, which ironically are feeding today’s severe fires.”

On average, fires in the United States today are nearly five times larger than fires from just forty years ago, and the fire season is two months longer. Most of the nation’s worst fire years in terms of total acres burned has come since 2000, and the U.S. Forest Service estimates about half of the forested land they manage is at risk to severe fires and in need of restoration.

Ryan says other factors also contributed to the mid-seral bulge seen in our forests today.“We did a lot of clearcutting mid-century, which also created large swaths of same-age stands of forest vulnerable to big, uncharacteristically severe fires.”

 

Big Burn Graphic © Nathan Welch/TNC

Clearwater Basin

In the Clearwater Basin of Idaho where Ryan works, The Nature Conservancy and its many partners are reducing the density of trees and restoring forests to a more historic, natural condition, where a mosaic of tree ages and heights provide better habitat and reduce severe fire risk. In other words, they are losing the mid-seral bulge.

“Over the past five years our forest collaborative has helped the Forest Service treat 75,000 acres of forest to improve wildlife habitat and lower severe fire risk, while creating and maintaining 653 local jobs in the process. That’s an accomplishment all of the partners can be proud of.”

Much of the Clearwater work was accomplished through support from the federal Collaborative Forest Landscape Restoration Program, which also funds 22 other forest restoration projects around country. Since 2010 this program has reduced the risk of uncharacteristically severe fire on 1.3 million acres, improved wildlife habitat on 1.2 million acres, and generated $661 million in labor income for local workers.

 

“Our forests face a lot of challenges these days, mid-seral bulge is just one thing,” Ryan says. “Climate change is daunting, and we need to figure out a better way to fund proactive and reactive firefighting.  But another lesson we learned from the Big Burn is that nature is resilient. If we don’t give up on nature, it won’t give up on us.”

Kelly Creek in the Clearwater Basin where the Conservancy is working with partners to help the forest lose its mid-seral bulge © Bill Mullins