Is prescribed fire science still developing?

Last week the Secretary of the Department of Sustainability and Environment (DSE) in Victoria, Australia told the Royal Commission that is looking into last year’s Black Saturday fires that he would not support a 4 to 6 percent increase in prescribed burning, partly because the science was still developing.

But a seven-member panel made up of fire ecologists, CSIRO fire researcher Phil Cheney, and Jerry Williams, former Chief of the U. S. Forest Service, said there is plenty of science available to support burning 5 to 10 percent of Victoria’s forests each year.

Cheney said a good prescribed fire will stop a bushfire for one to two years, and after three years will have a “profound effect” in reducing the rate of spread. For as long as 20 years embers and flame height will be reduced.

Jerry Williams said prescribed fire had an effect even in extreme conditions.

A person might say the science of prescribed burning has been developing for many centuries since indigenous people began routinely setting prescribed fires to enhance the habitat for the plants and animals they needed for survival. In 1804 and 1805 Lewis and Clark documented the use of prescribed fire by native Americans (but at least one of them had an unfortunate result). At some point we have to admit that the science has reached a level of maturity.

Abraham Lincoln said:

Things may come to those who wait…but only the things left by those who hustle.

From the DSE’s Fire Ecology web page:

Fire is a natural part of the Australian environment and has been so for millions of years. Natural ignition (lightning) and indigenous burning practices have shaped our ecosystems over tens of thousands of years.

From Bill Gabbert, February 22, 2010:

Prescribed fire, when applied wisely by experienced fire management personnel, is an essential land management tool.


via @FireInfoGirl

Researchers study how prescribed fires affected Black Saturday fires

Research scientist Lachlan McCaw led a team that studied the effects that previous planned or unplanned fires had on the spread of the disastrous Black Saturday fires a year ago in Australia. Unsurprisingly, he concluded that the intensity was reduced and the areas provided anchor points for firefighters, but larger prescribed fires were more effective than small ones.

DUH. To many of us this is intuitive, but documenting this data can help to rebut the uninformed rants of those in Australia that are opposed to prescribed fires.

Here is an excerpt from a report in The Australian:

Dr McCaw said that across the areas burned on Black Saturday, there was no evidence that small-area fuel reduction had curbed the fires, but strong evidence of an impact where planned or unplanned burns had occurred within four years and over broad areas of more than 600ha.

Where the Kilmore fire, burning with great intensity about 3pm on Black Saturday, met a relatively small area of four-year-old growth, it was quickly outflanked.

About 6.30pm, when the fire met a 1600ha area burnt by wildfire in January 2006, it burned with low intensity.

Dr McCaw said the severity of the Beechworth fire on Black Saturday was reduced by burns that had been conducted one year, two years and four years previously, that had also provided “anchor points” for fire fighting.

Asked about the effectiveness of small “mosaic” burns that left areas of unburnt vegetation for biodiversity conservation, Dr McCaw said if the primary objective of planned burning was community protection, “you would have to be pursuing fairly high levels of fuel reduction”.

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