UPDATE at 2:11 p.m. MT, Feb. 16, 2012:
We contacted Nan Christianson, the Assistant Station Director – Communications at the Rocky Mountain Research Station, and asked where they stood on Open Access, and why the study, below, was only available to taxpayers if they paid $31.50 to a private company. Within a few hours they added it to a U.S. Forest Service web site, TreeSearch, where it is available at no charge. It is still listed at the private company for $31.50. We are waiting for more detailed information from the USFS concerning their policy on the Open Access of taxpayer-funded research.
February 15, 2012
At Wildfire Today we have previously written about mountain pine beetle research that used satellite data and computer models to extrapolate findings to fire behavior characteristics. Now there is a new study that measured foliar chemistry, moisture, and flammability in the lab and also draws a conclusion about fire behavior out in the real world.
The latter study, which is published behind a pay wall in the April, 2012 edition of Elsevier’s Forest Ecology and Management, was written by Matt Jolly and others at the U.S. Forest Service’s Rocky Mountain Research Station. In their study, foliar samples were taken periodically from multiple trees identified as green, recently attacked by mountain pine beetles, and red (dead). The fuel moisture content, chemical composition, and time to ignition of needles from each attack category were quantified. They found that in the lab, decreased moisture content and changes in foliar chemistry increased the flammability of beetle-attacked foliage, and red needles ignited much more quickly than green needles. They further extrapolated that “crown fire potential may be higher in attacked stands as long as foliage is retained on the tree”.
You can read the study, which American taxpayers paid for already, but you will have to pay the for-profit Elsevier corporation $31.50. This is not Open Access, which we have written about before. (The U.S. Forest Service should publish the results of all of their research immediately upon completion at no additional cost to American taxpayers. What is the point of the USFS funding research if the results are kept a virtual secret?)
In an earlier study, University of Wisconsin forest ecologists Monica Turner and Phil Townsend, in collaboration with Yellowstone National Park Vegetation Management Specialist Roy Renkin, examined the beetle and fire connection in the forests near Yellowstone National Park.
Using satellite data they studied burn patterns and fire occurrence data and the relationships to mountain pine beetle attacks.
Here is an excerpt from the NASA article:
Their preliminary analysis indicates that large fires do not appear to occur more often or with greater severity in forest tracts with beetle damage. In fact, in some cases, beetle-killed forest swaths may actually be less likely to burn. What they’re discovering is in line with previous research on the subject.
The results may seem at first counterintuitive, but make sense when considered more carefully. First, while green needles on trees appear to be more lush and harder to burn, they contain high levels of very flammable volatile oils. When the needles die, those flammable oils begin to break down. As a result, depending on the weather conditions, dead needles may not be more likely to catch and sustain a fire than live needles.
Second, when beetles kill a lodgepole pine tree, the needles begin to fall off and decompose on the forest floor relatively quickly. In a sense, the beetles are thinning the forest, and the naked trees left behind are essentially akin to large fire logs. However, just as you can’t start a fire in a fireplace with just large logs and no kindling, wildfires are less likely to ignite and carry in a forest of dead tree trunks and low needle litter.
A third study published in 2011 used computer models to predict fire behavior and how it was affected by beetle attacks. It was titled “Do mountain pine beetle outbreaks change the probability of active crown fire in lodgepole pine forests?” Here is an excerpt from the abstract:
Modeling results suggested that undisturbed, red, and gray-stage stands were unlikely to exhibit transition of surface ﬁres to tree crowns (torching), and that the likelihood of sustaining an active crown ﬁre (crowning) decreased from undisturbed to gray-stage stands. Simulated ﬁre behavior was little affected by beetle disturbance when wind speed was either below 40 km/h or above 60 km/h, but at intermediate wind speeds, probability of crowning in red- and gray-stage stands was lower than in undisturbed stands, and old post-outbreak stands were predicted to have passive crown ﬁres. Results were consistent across a range of fuel moisture scenarios. Our results suggest that mountain pine beetle outbreaks in Greater Yellowstone may reduce the probability of active crown ﬁre in the short term by thinning lodgepole pine canopies.
The paper was written by Martin Simard, William H. Romme, Jacob M. Griffin, and Monica G. Turner. A summary of their findings is HERE.
All three of these studies, while they collected some static data from the field, were executed in laboratories, and not from observed fire behavior in the real world.
So which school of thought do you subscribe to? Do you go with the most intuitive-friendly one and think lower foliar moisture content leads to more crown fires in beetle-kill areas, or do you buy into the satellite burn data and the computer model data which lean toward more resistance to crown fires in areas affected by beetles?
It may take another International Crown Fire Experiment (see photo above), like was done in Canada between 1995 and 2001, setting actual fires in healthy and beetle-affected stands, to resolve the question.