Young pine trees face new peril from mountain pine beetle

New research from the University of Alberta's Faculty of Agricultural, Life and Environmental Sciences shows that pine beetle attacks not only lead to the death of adult trees, but can also leave the next generation of pine vulnerable to future insect attack.

"The next pine forest is at risk," said Justine Karst, an assistant professor in restoration ecology in the Department of Renewable Resources. She's the co-lead author of a new study with Nadir Erbilgin, Canada Research Chair and associate professor in forest entomology and chemical ecology.

Karst said the beetles, which have damaged or killed more than 47 million hectares of mainly lodgepole pine forests in western North America in the past decade, start an unexpected chain of events that increase the vulnerability of future forests to damage.


Beetle Plague Spurs Canadians on U.S. Lumber-Mill Buying Spree

In the 60 years since Bob Jordan III joined his family’s North Carolina sawmill business, he hasn’t seen anything quite like the Canadian invasion of the South’s lumber industry.

“You didn’t have people coming in from the outside -- we never had this before,” Jordan, 82, president of closely held Jordan Lumber & Supply Inc., said about an estimated C$2 billion ($1.62 billion) wave of Canadian investment. “Over 50 percent of the lumber in a certain part of the South is being produced by the Canadian mills.”

Western Canadian lumber producers have good reason to be looking to the southeast corner of the continent. Chased from their home forests by rising costs and a plague of tree-killing beetles, West Fraser Timber Co., Canfor Corp. and Interfor Corp. have been on a buying spree, doubling the number of mills they own in the South since 2009 to about 34. The Canadians are drawn by the region’s 210 million acres of fast-growing forests and expanding housing markets from Texas to Virginia to Florida, according to Brooks Mendell, president of Forisk Consulting, an Athens, Georgia-based timberland researcher.


Next generation of pine beetles threatening North America

The most destructive pest to North America's mature pine forests, the mountain pine beetle, is threatening the next generation.

A study conducted by a University of Alberta researcher shows that the pine beetle not only kills adult trees, but can also leave the next generation of pine vulnerable.

"The next pine forest is at risk," said Justine Karst, an assistant professor in restoration ecology at the U of A, and co-lead author of the study with Nadir Erbilgin, Canada research chair and associate professor in forest entomology and chemical ecology.


Forests killed by the mountain pine beetle don't pose increased wildfire risk

In the past decade, the mountain pine beetle has severely impacted pine forests across more than 50 million acres of western North America. In the aftermath of this epidemic is there a significant increase in wildfire threat? For many tasked with managing wildfires the answer is a resounding "yes." However, a recent research paper from a team of scientists based in Colorado suggests that forests killed by the mountain pine beetle do not pose an increased risk to wildfire. The paper relies on the recent area burned in wildfire superimposed on the area recently infested by the beetle. Because the areas of recent wildfires and beetle activity don't overlap, the authors contend that the risk posed by the mountain pine beetle is overblown. Those in the wildland fire management and suppression fields who disagree base their disagreement on actual observations of extreme fire behavior in forests killed by the mountain pine beetle.

So who is correct in this debate? A paper published in 2014 in the online journal Fire Management Today sought to address this problem by looking at two critical factors: the history of beetle attacks in a forest and the time since beetle infestation. To many people, it would seem that the year after initial infestation when the tree crowns all turn red is the time of highest risk. It certainly can be, provided other elements of hazard are also present. Red-attacked trees, in addition to heavy accumulations of dead wood on the forest floor, are a recipe for extreme fire behavior. Red-attack trees and very little or no dead wood on the forest floor is much less of a risk and, once the needles fall off dead trees, fire risk can be low for quite some time.

The authors of the paper challenging wildfire risk do not describe the fuel structure in these forests - only the state of the tree crowns (red or grey). The lack of attention to surface fuels is a weak point in such studies. Throughout much of British Columbia, Canada, over the last several decades mountain pine beetle outbreaks have been fairly common. With each passing epidemic more and more trees in the forest are killed by beetles. After large outbreaks with high mortality, dead trees gradually fall and accumulate on the forest floor. Heavy accumulations of downed wood associated with past beetle outbreaks have contributed to some very impressive fire behavior. Since 2009, British Columbia has seen large areas of beetle-killed forest burn under very high intensity and severity with much of the area burned having experienced significant epidemics in the 1980s and mid-2000s. The fuel structure in these forests has included red and grey crowns plus large quantities of dead wood on the forest floor. Unfortunately, to mitigate the threat there are only a few options and none are very palatable to the public. An increase in logging of the attacked or soon to be attacked trees has been advocated for large areas in the West but it can often lead to a worse fuel hazard if not done diligently; large-scale prescribed burning has been done in some areas with the intent of breaking up a contiguous landscape of fuel; and, relying on natural ignitions to reduce the hazard can be effective provided the fire doesn't burn too severely.


Study Exonerates Beetle From Claims Of Added Wildfire Risk

It is climate change, not the mountain pine beetle, we should be worried about.

Researchers have found that forests infested by the mountain pine beetle (Dendroctonus ponderosae), which is present in thousands of miles of forest in western North America from Mexico to British Columbia, has no added effect on the risk of wildfires compared to forests unaffected by the insect. Instead, it is more important for policy makers to address the bigger causes of forest fires, the researchers say.

"The bottom line is that forests infested by the mountain pine beetle are not more likely to burn at a regional scale," says Sarah Hart, postdoctoral researcher at the Colorado University-Boulder and lead researcher. "We found that alterations in the forest infested by the mountain pine beetle are not as important in fires as overriding drivers like climate and topography."