Contrary to common belief, wildfires popping up in the dry forests of the West in recent years are not bigger and badder than those in the distant past.
That is according to findings by scientists at the University of Wyoming at Laramie.
A 2010 study of a 30-foot core sample taken from the bottom of upper Squaw Lake in the Applegate River watershed found intense fires were common in the region going back 2,000 years.
The study by scientists Daniele Colombaroli and Daniel G. Gavin, which dated charcoal layers in the sediment core, determined that current wildfires are no more severe than during the past two millennia.
Gavin is an assistant professor at the Department of Geography at the University of Oregon. Colombaroli, a former post-doctoral researcher in the department at UO, teaches at the University of Bern, Switzerland.
A 2009 regional study by Ashland ecologists Dominick DellaSala and Dennis Odion that used satellite images also concluded that wildfires are no more severe now than in the past.
Based on studies of copious notes written by General Land Office surveyors around 1880 in Oregon, Colorado and Arizona, fire and landscape ecology professor William Baker and Mark Williams, who recently completed his doctorate in ecology at the university, conclude that many wildfires back in the day were as intense as those in the latter part of the 20th century and early 21st century.
In addition to determining that more highly intense fires are not occurring now, they found much more forest diversity, in part from the areas having experienced a wide range of wildfire behavior over time, Baker told the Mail Tribune.
That means that current practices of land-management agencies need to be reassessed, he said.
"Our study suggests that current management approaches will not generally restore these forests, if used uniformly across large areas, not because of poor management, but because managers did not know that these forests were historically much more variable in density and fires than previously thought," Baker said.
"The advantage of restoring them is that these forests have been through thousands of years of climatic change, fires, droughts and beetle attacks," he continued. "Their historical structure and variability in that structure is perhaps not all that is needed, but is among the best insurance available that they will be able to respond to a variety of future threats."
Baker and Williams' findings, published earlier this year in Global Ecology and Biogeography, fly in the face of other opinions that fire suppression over the past century has resulted in more intense fires in modern times, observed Dominick DellaSala, a forest ecologist and chief scientist at the Geos Institute, an environmental think tank in Ashland.
"Bill is a paradigm smasher, and that is a good thing in science," DellaSala said. "If we get too locked in on something, it becomes a self-fulfilling truth."
DellaSala sees the studies as important components in the growing body of research among ecologists studying wildfires and their impacts on forestlands.
The consensus has been that the forests a century ago and beyond were park-like and endured only low-level fires, he concurred.
"The interesting thing about this debate over what Bill has brought to the table with his analysis is that it highlights the fact we have a tendency to look at the world through a very short time frame," DellaSala said. "We tend to look at the world in the lifetime of a person or even less. But nature operates on a much longer time horizon.
"If you look back at cyclical, long-term trends in the relationship between forest and climate, you get an interesting picture," he added. "How you draw your conclusions depends on where you enter that time slice."
The bottom line, he said, is that looking at a smaller time slice can cause the study to be incomplete.
"We need to be looking at as much of a time frame as we can to get the complete picture," he said. "The debate in ecology right now is very time and location specific. We are trying to extrapolate beyond the bounds of what we can do with these studies. It is a healthy debate."
But Tom Sensenig, the U.S. Forest Service's ecologist for southwestern Oregon, says the research offers little relevance for today's forest-management practices.
"What is important is the current condition of our forests relative to its risk of fire and the ecological consequences when they burn today," he said.
"Let's assume for a moment that Baker's interpretation is correct and that the majority of forest stands were very dense and routinely burned up entirely in fires — so what?" he added. "That doesn't mean that this scenario is desirable or meets the objectives defined for our forests today."
Moreover, he said, the interpretation of their research is not consistent with that reached by agency scientists in their studies.
"We also know that most, if not all, of our older forest stands survived multiple fires over their lifetime, yet they increasingly no longer survive when they burn today as a result of the increase in available fuel that has accumulated over the last 100 years or so," he said.
"We use measurable facts in our analyses, as opposed to broad-scale generalizations to make assertions based solely on the interpretation of descriptions written by others," he added.
The General Land Office survey information was filled with precise details long overlooked by scientists seeking answers to yesterday's forests, noted Baker, a member of a U.S. Fish and Wildlife Service working group developing plans to help bolster northern spotted owl populations in dry forests.
In addition to poring over some 13,000 surveyor descriptions of forests, Baker and Williams retraced the surveyors' steps on the ground, covering more than 250 miles. The accuracy and error rates of the survey data have been analyzed in an extensive statistical trial published in Ecological Monographs, one of the world's top ecological science journals, Baker said.
Of the 1 million acres they studied in the past two years, about 26 percent had evidence of high-intensity fire at the time of the surveys, while 50 percent had experienced low- and mixed-severity fires, he said.
They also found that understory trees and shrubs were historically abundant on 84 percent of the dry forest area, while small trees and shrubs were dense across 45 percent of the landscape, he said.
"Thinning a forest may make the surviving larger trees more resistant to damage in future fires, but fire is not the main worry for these forests in the future," he said.
"The large trees are the ones least likely to survive impending changes," he continued. "Larger trees are actually more prone to scarring in fires, which leaves them with more wounds that allow fungi to rot the tree."
Small trees, in contrast, are more likely to survive droughts, he said, noting they have less tissue to support.
"Just as in human populations, the kids represent the best hope for the future," he said. "It is sensible insurance to not thin the small trees, or at least leave lots of them."
Reach reporter Paul Fattig at 541-776-4496 or email him at firstname.lastname@example.org.