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| Signs of 2002’s Missionary Ridge Fire are still visible from the Animas Valley. Although it’s known that fire can be beneficial for the forest, a new study sheds light on how vital a tool fire is in forest management./ Photo by Steve Eginiore |
Fuel for the fire
Study further demonstrates benefits of the burn in the backcountry
by Tracy Chamberlin
The instinct is to put the fire out. Grab the bucket of water or the hose and snuff out the flames.
The instinct is to put the fire out. Grab the bucket of water or the hose and snuff out the flames.
But when it comes to the forest, fire is part of the natural cycle. In fact, the fight to suppress fires might just be making things worse.
“You can only put them out for so long,” said Julie Korb, assistant professor in the Biology Department at Fort Lewis College.
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Just the Facts
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Korb will talk about fire, its relationship to the mixed conifer forests of the San Juans and land management practices that can benefit that relationship at 6:30 p.m. Tuesday at the college’s Center of Southwest Studies.
For more than a century, the Forest Service’s goal has been to fight fire. But, the results of that protocol have actually disrupted the relationship between the forest and its natural fire regime. This has left the forest more vulnerable to high-intensity crown fires, which can destroy not just the diversity of the forest but its ability to recover. It could also facilitate the introduction of a new type of ecosystem, changing the natural balance of the forest.
“We need to put fire back into these ecosystems,” Korb said.
In 2002, the year of the Missionary Ridge Fire, Korb and her colleagues began a study of warm/dry mixed conifer forests in Southwest Colorado. Her talk, “High Variability of Mixed Conifer Forests in the San Juan Mountains: Implications for Ecological Restoration,” explains the methods and results of that 10-year study.
She also plans to touch on some information gathered at the Southwest Fire Ecology Conference she attended at the end of February in Santa Fe.
What Korb hopes people will take away from her talk, sponsored by the San Juan/Four Corners Native Plant Society, is that “all fire is not the same.”
Korb and her colleagues began the study by determining the history of fire in the mixed conifer forest. They used dendrochronology, the science of studying tree rings, to reconstruct past forest conditions.
The team looked at tree rings and fire scars to determine the forest’s previous relationship with fire. Korb said this is the first time this type of data has been used to design and test restoration treatments. Korb plans to bring some of the tree ring samples to the lecture, so she can show, not just tell, about the forest’s history.
According to her tree rings, fires occurred approximately every 10 years. “Fire is a part of this landscape and always will be,” Korb said.
Restoring forests to that historical timetable would ultimately make the forest more resistant to the devastating fires common in today’s warmer, drier climate.
In the past, land managers have focused on keeping controlled burns confined to the surface, not allowing them to grow to the canopy. But Korb said when the burn area is not surrounded by homes, it is all right to let crown fires burn in small patches.
When fires are suppressed, they can often return with vigor, burning hotter and destroying more acreage, like 2011’s Wallow Fire in New Mexico, which scorched 470,000 acres.
According to Korb, 90 percent of fire money goes toward fighting fires and protecting the wildland-urban interface, where homes butt up to natural terrain.
This sort of reactive attitude has been the approach of land management for the past century, but Korb said it’s time to become proactive. After all, fire danger is only expected to intensify as the Southwest grows warmer and drier, as predicted.
Some of the evidence in favor of this argument is in the trees. In the study, a control area of mixed-conifer, which saw no thinning or controlled burns, experienced a 22 percent decrease in tree density over a six-year period.
“What’s happening is that the trees are stressed,” Korb said.
This is not considered a significant tree mortality rate, but it can have future implications. An ecosystem already susceptible to insects and pathogens due to drought will require a different approach to land management.
In order to discover if thinning and burning could help forest restoration, the team set up three areas of study, each given a different treatment. One received tree thinning and a controlled burn; another received the burn only; and the third was the control area, where no mitigation took place.
Prior to any treatment, the areas were examined in 2003 for fire history and ecological diversity. The areas were examined again in 2009, after administering the burn and burn/thinning.
The team discovered the area that was thinned and burned most closely resembled historical conditions and recovered the quickest. However this was also the most costly area. The burn-alone area showed signs of a slower recovery, albeit at a much cheaper cost.
But it’s not all about the burn. Korb plans to tell attendees why the mixed conifer forest matters and why it is so important to the overall health of the forest.
Ponderosa pine forests, another key subsection of the San Juan Mountains, are known to be highly tolerant of drought and fire. Mixed conifer forests, on the other hand, are poorly understood and difficult to characterize because of their diversity, according to Korb. Known as “transition forests,” they are an important ecosystem and no two are alike. The ones in California are very different from the ones in Colorado, and even the ones on the Front Range and different from the ones in the San Juans.
One of the conclusions of the 10-year study is that more site-specific studies are needed to make the best recommendations to land managers. After all, the study is not just about appreciating the importance of the forest. The results can help land managers develop plans to work with the natural fire cycle and stay ahead of the flames as the climate gets drier and warmer.
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