Radiant heat, embers, and the ignitability of structures

Here are a couple of interesting videos featuring Jack Cohen, a researcher at the Missoula Fire Science Lab. The videos explain radiant heat and how difficult it is for fine fuels and structures to ignite from that alone, and the role of embers in spreading fire and burning structures.

via @FireInfoGirl

John Muir Project: “The myth of ‘catastrophic’ wildfire”

The Director of the John Muir Project, Chad Hanson, has written a paper about wildfire and its relationship to biodiversity and climate change, titled The Myth of ‘Catastrophic’ Wildfire. Here are some of his findings, as reported by New West:

• There is far less fire now in western U.S. forests than there was historically.

• Current fires are burning mostly at low intensities, and fires are not getting more intense, contrary to many assumptions about the effects of climate change. Forested areas in which fire has been excluded for decades by fire suppression are also not burning more intensely.

• Contrary to popular assumptions, high-intensity fire (commonly mislabeled as “catastrophic wildfire”) is a natural and necessary part of western U.S. forest ecosystems, and there is less high-intensity fire now than there was historically, due to fire suppression.

• Patches of high-intensity fire (where most or all trees are killed) support among the highest levels of wildlife diversity of any forest type in the western U.S., and many wildlife species depend upon such habitat. Post-fire logging and ongoing fire suppression policies are threatening these species.

• Conifer forests naturally regenerate vigorously after high-intensity fire.

• Our forests are functioning as carbon sinks (net sequestration) where logging has been reduced or halted, and wildland fire helps maintain high productivity and carbon storage.

• Even large, intense fires consume less than 3% of the biomass in live trees, and carbon emissions from forest fires is only tiny fraction of the amount resulting from fossil fuel consumption (even these emissions are balanced by carbon uptake from forest growth and regeneration).

• “Thinning” operations for lumber or biofuels do not increase carbon storage but, rather, reduce it, and thinning designed to curb fires further threatens imperiled wildlife species that depend upon post-fire habitat.

In addition to being the Director of the John Muir Project, Mr. Hanson is also a researcher at the University of California at Davis and was elected as one of the directors of the Sierra Club in 2000.

Forest fire carbon emissions grossly overestimated

Researchers are saying that previous researchers’ estimates of carbon emissions from wildfires were seriously overestimated due to erroneous assumptions about the amount of organic material that actually burned. The new research does not go so far to say that “wood smoke is good smoke”, but they do use my new favorite word, “pyrodiversity”.

From the New West:

CORVALLIS, Ore. – A recent study at Oregon State University indicates that some past approaches to calculating the impacts of forest fires have grossly overestimated the number of live trees that burn up and the amount of carbon dioxide released into the atmosphere as a result.

The research was done on the Metolius River Watershed in the central Oregon Cascade Range, where about one-third – or 100,000 acres – of the area burned in four large fires in 2002-03. Although some previous studies assumed that 30 percent of the mass of living trees was consumed during forest fires, this study found that only 1-3 percent was consumed.

Some estimates done around that time suggested that the B&B Complex fire in 2003, just one of the four Metolius fires, released 600 percent more carbon emissions than all other energy and fossil fuel use that year in the state of Oregon – but this study concluded that the four fires combined produced only about 2.5 percent of annual statewide carbon emissions.

Even in 2002, the most extreme fire year in recent history, the researchers estimate that all fires across Oregon emitted only about 22 percent of industrial and fossil fuel emissions in the state – and that number is much lower for most years, about 3 percent on average for the 10 years from 1992 to 2001.

The OSU researchers said there are some serious misconceptions about how much of a forest actually burns during fires, a great range of variability, and much less carbon released than previously suggested. Some past analyses of carbon release have been based on studies of Canadian forests that are quite different than many U.S. forests, they said.

“A new appreciation needs to be made of what we’re calling ‘pyrodiversity,’ or wide variation in fire effects and responses,” said Garrett Meigs, a research assistant in OSU’s Department of Forest Ecosystems and Society. “And more studies should account for the full gradient of fire effects.”

The past estimates of fire severity and the amounts of carbon release have often been high and probably overestimated in many cases, said Beverly Law, a professor of forest ecosystems and society at OSU.

“Most of the immediate carbon emissions are not even from the trees but rather the brush, leaf litter and debris on the forest floor, and even below ground,” Law said. “In the past we often did not assess the effects of fire on trees or carbon dynamics very accurately.”

Even when a very severe fire kills almost all of the trees in a patch, the scientists said, the trees are still standing and only drop to the forest floor, decay, and release their carbon content very slowly over several decades. Grasses and shrubs quickly grow back after high-severity fires, offsetting some of the carbon release from the dead and decaying trees.

Thanks Dick

Researchers: smoke promotes the germination of some seeds

We used to say “Wood smoke is good smoke”, when downplaying the negative aspects of putting smoke into the air during a prescribed fire. But apparently to some species that is literally the truth. Researchers have found that plant-derived smoke is a potent seed germination promoter for many species.

From an article in Science Daily:

Forest fire smoke. Photo by Bill Gabbert
Photo: Bill Gabbert

The innermost secrets of fire’s role in the rebirth and renewal of forests and grasslands are being revealed in research that has identified plant growth promoters and inhibitors in smoke. In the latest discovery about smoke’s secret life, an international team of scientists are reporting discovery of a plant growth inhibitor in smoke.

The study appears in ACS’s Journal of Natural Products.
“Smoke plays an intriguing role in promoting the germination of seeds of many species following a fire,” Johannes Van Staden and colleagues point out in the report. They previously discovered a chemical compound in smoke from burning plants that promotes seed germination. Such seeds, which remain in the undercover on forest and meadow floors after fires have been extinguished, are responsible for the surprisingly rapid regrowth of fire-devastated landscapes.

In their new research, the scientists report discovery of an inhibitor compound that may block the action of the stimulator, preventing germination of seeds. They suspect that the compounds may be part of a carefully crafted natural regulatory system for repopulating fire-ravaged landscapes. Interaction of these and other compounds may ensure that seeds remain dormant until environmental conditions are best for germination. The inhibitor thus may delay germination of seeds until moisture and temperature are right, and then take a back seat to the germination promoter in smoke.

The research was conducted at the University of KwaZulu-Natal, the University of Stellenbosch, the University of Copenhagen,  and the Academy of Sciences of the Czech Republic.

Thanks Stephen

Series of articles about wildfire, by Miller-McCune

The Miller-McCune web site has started a five-part series about wildfire.


Here is a brief excerpt from Part 1, which covers at length many different options and technologies for collecting and distributing real-time or near-real time intelligence about going fires.

The Viz Lab is a large, dimly lit, war room dominated by huge, computer-generated maps projected onto dark walls. Its tool kit includes an array of links to information and imaging feeds gathered by satellites, airplanes, unmanned aerial vehicles (or UAVs) and helicopters from sources like NASA and Google Maps. The lab is bent on delivering real-time (or pretty darned close) computer mapping and imaging to a wildfire’s first responders so they’ll know just what the blaze is doing, where and when.

Data fusion is the name of the game at the San Diego State University’s Immersive Visualization Center — layering sophisticated weather, atmospheric, smoke and fire data and images onto, say, a topographical Google Earth map. It provides an illuminating picture for emergency operations chiefs who urgently need to pinpoint trouble spots and interpret fast-changing developments.

Once, fire perimeters were indicated by simple black lines on old-fashioned land maps — best guesses made from the field without benefit even of GPS. Now, satellites or aircraft use “look down” technology to create 3-D topographical images of what lies below dark, billowing smoke. Tools distinguish live from burned vegetation and show in various colors rapidly updated information on a blaze’s “hot spots” and accelerating or subsiding dangers.

“It’s absolutely dramatically more useful,” explained Eric Frost, co-director of the Viz Lab.

The Viz Lab normally focuses on geographic information systems research for homeland security and disaster relief. But it also proactively tracks everything from brush fires on its doorstep to natural disasters worldwide. Last February, for example, it helped map wildfires in Australia that killed 173 people. “It takes less than half a second to go from here to Australia on fiber optics,” Frost noted.

Here is a video about an unmanned aerial vehicle, or UAV, being developed by San Diego State University. The researchers have been working with firefighters in an attempt to show them its usefulness on fires.

Researchers: chimpanzees can predict fire behavior

Researchers from Iowa and Pennsylvania have concluded that chimpanzees have a basic understanding of wildland fire behavior and can predict the movement of a fire. Here is an excerpt from physorg.com:


The use and control of fire are behavioral characteristics that distinguish humans from other animals. Now, a new study by Iowa State University anthropologist Jill Pruetz reports that savanna chimpanzees in Senegal have a near human understanding of wildfires and change their behavior in anticipation of the fire’s movement.

An ISU associate professor of anthropology, Pruetz and Thomas LaDuke, an associate professor of biological sciences at East Stroudsburg (Pa.) University, co-authored the paper, which will be posted online Friday by the American Journal of Physical Anthropology. It will be published in a 2010 edition of the journal.

Data on the chimps’ behavior with seasonal fires was collected by Pruetz during two specific encounters in March and April 2006. She reports that wildfires are set yearly by humans for land clearing and hunting, and most areas within the chimpanzees’ home range experience burning to some degree.

Chimps have calm understanding of wildfires

The researchers interpret the chimpanzees’ behavior to the wildfires as being predictive, rather than responsive, in that they showed no signals of stress or fear — other than avoiding the fire as it approached them.

“It was the end of the dry season, so the fires burn so hot and burn up trees really fast, and they [the chimps] were so calm about it. They were a lot better than I was, that’s for sure,” said Pruetz, who was selected a 2008 National Geographic Emerging Explorer for her previous research on the savanna chimpanzees at the Fongoli research site in Senegal.

“They [the chimps] were experts at predicting where it was going to go,” she continued. “I could predict it, sort of, but if it were just me, I would have left. At one time, I actually had to push through them because I could feel the heat from the fire that was on the side of me and I just wasn’t that comfortable with it.”

Pruetz says it was hard to find previous research on how other animals interacted with fire. But the few examples that she and LaDuke found — such as elephants’ encounters with similar wildfires — reported that those animals were highly stressed and experienced high mortality rates.

In their paper, the researchers wrote that the control of fire by humans involves the acquisition of these three cognitive stages:

1. Conceptualization of fire. An understanding of the behavior under varying conditions that would allow one to predict its movement, thus permitting activity in close proximity to the fire.
2. The ability to control fire. Involving containment, providing or depriving the fire of fuel and perhaps the ability to put it out.
3. The ability to start a fire.

According to Pruetz, the Fongoli chimpanzees have mastered the first stage, which is the prerequisite to the other two. But she doesn’t see them figuring out how to start a fire anytime soon — at least, not without help.

“I think they could learn. It might be difficult only because of their dexterity, since they’re less dexterous than us,” she said. “But naturally, I can’t ever see them making fire. I think cognitively they are able to control it (stage 2).”


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