[MCN] Insect-killed forest at less, not more, risk of fire

Lance Olsen lance at wildrockies.org
Fri Apr 29 11:21:28 EDT 2016

Insect outbreaks reduce wildfire severity
Pine beetle, budworm outbreaks dampen forest fire impacts

Forest scientists have found an unexpected 'silver lining' to the 
insect outbreaks that have ravaged millions of trees across western 
North America.

While insect outbreaks leave trees looking like matchsticks, a new 
University of Vermont-led study finds these hungry critters 
significantly reduce wildfire severity.

The findings contrast sharply with popular attitudes - and some U.S. 
forest policies - which connect tree-eating insects with increased 
wildfire activity.

"This is surprising," says UVM forest scientist Garrett Meigs, lead 
author of the study. "Forest fires and insect outbreaks have 
increased in recent decades, causing some people to link the two in 
their minds."

"Our findings clearly show that insect outbreaks can reduce burn 
severity," says Meigs, a researcher at UVM's Gund Institute and 
Rubenstein School of Environment and Natural Resources. "So there is 
a connection, but just not the way most people thought."

The study, by scientists at UVM and Oregon State University, is 
published in the journal Environmental Research Letters. OPEN ACCESS

Analyzing 81 fires over 25 years, the study is the largest to date on 
forest fire severity following insect outbreaks. Researchers focused 
on sites in Oregon and Washington State with past outbreaks by the 
mountain pine beetle or western spruce budworm, two of North 
America's most destructive insects.

Wildfires in areas that experienced greater insect damage in the past 
burned with significantly less severity, regardless of fire size, 
season or drought conditions. The researchers measured burn severity 
- or vegetation loss - using satellite imagery taken before and after 
each fire.

"There is huge concern that insect outbreaks and forest fires will 
continue to increase with climate change," says UVM forest ecology 
professor Bill Keeton, a study co-author. "These threats remain 
significant, but our study suggests that major insect outbreaks, 
contrary to current thinking, can dampen future fire impacts - and we 
can use that knowledge to improve forest management."

The researchers say the findings can be explained by "forest 
thinning," which occurs when insects kill some trees and leave others 
to survive. This lowers forest density, which reduces the amount of 
fuel available for subsequent fires.

The study builds on previous research by Meigs and colleagues, which 
found that insect outbreaks in the Pacific Northwest did not increase 
the likelihood of wildfires.

The results give new insights to communities and forest agencies 
dealing with the effects of insect outbreaks on forestry, tourism and 

For example, the 2014 U.S. Farm Bill included fuel reduction 
provisions for forests with insects and diseases. The study suggests 
that forest managers may be able to factor in the natural "thinning 
effects" of insects into these efforts.

And while both insects reduced fire severity, each critter exhibited 
unique patterns that require different approaches by forest agencies.

"These findings will help forest managers to better prioritize 
restoration efforts designed to reduce fire risks," says Keeton, 
chair of UVM's Forestry Program.

While previous studies explored a handful of fires for shorter 
periods, recently released satellite imagery and data enabled the 
researchers to analyze a much greater number of fires over longer 
periods. The team used advanced spatial statistical analyses to 
decipher insect-fire interactions in areas with past outbreaks of 
these two key insects.

"Together, these studies tell us that not only can insects reduce 
forest fire likelihood - they also reduce potential forest fire 
impacts," says Meigs, summarizing his two recent papers on fire risk 
and severity.

"We can reduce our risks by disincentivizing housing development in 
fire-prone areas, better managing public land and rethinking the 
effectiveness of our current firefighting approach."

Incorporating Anthropogenic Influences into Fire Probability Models: 
Effects of Human Activity and Climate Change on Fire Activity in 
Michael L. Mann, Enric Batllori, Max A. Moritz, Eric K. Waller, Peter 
Berck, Alan L. Flint, Lorraine E. Flint, Emmalee Dolfi

Research Article | published 28 Apr 2016 | PLOS ONE (open access)
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://bigskynet.org/pipermail/missoula-community-news_bigskynet.org/attachments/20160429/234626f5/attachment-0002.html>

More information about the Missoula-Community-News mailing list