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Study: Bark beetle outbreak not the culprit in recent rash of western fires

Scott Black, Xerces Society for Invertebrate Conservation; (503) 449-3792,
Dominik Kulakowski, Clark University; (508) 793-7383, 
Barry Noon, Colorado State University; (970) 491-7905,
Dominick DellaSala, Chief Scientist and President of Geos Institute (541) 621-7223

PORTLAND, Ore.—A new paper published today in the Natural Areas Journal (click here for the full text) indicates that bark beetle outbreaks that have turned millions of acres of forests in the Inter-mountain West a noticeable red coloration (from tree death) do not substantially increase the risk of active crown fire in lodgepole pine and spruce forests as commonly assumed. Instead, “Do Bark Beetle Outbreaks Increase Wildfire Risks in the Central U.S. Rocky Mountains? Implications from Recent Research” documents evidence that active crown fires in these forest types are primarily triggered by dry conditions exacerbated by climate change.

“Outbreaks of mountain pine beetle and spruce beetle do not appear to substantially increase the risk of subsequent fire under most conditions,” said Dominik Kulakowski assistant professor of geography and biology at Clark University in Worcester, MA, and co-author of the paper. “Instead, fire risk is strongly tied to warm and dry conditions, such as those of recent decades. As long as the severe droughts we have been seeing in recent years persist, we can expect a high risk of fire—regardless of beetle outbreaks. The relationship is not so much that outbreaks lead to fires as much as it is that recent climatic conditions are increasing both outbreaks and fires. Fire risk has been increasing, but that increased risk is primarily driven by climate and not outbreaks. Drought is the trump card in this case,” Kulakowski said.  

Looking at multiple studies the paper also concludes that although preemptive thinning for bark beetle control may reduce susceptibility to small outbreaks there is no evidence that thinning will reduce susceptibility to large, landscape-scale epidemics. Also once beetle populations reach epidemic levels, logging measures aimed at stopping them are not likely to reduce forest susceptibility to outbreaks.  

“Drought and high temperature are likely the overriding factors behind the current bark beetle epidemic in the western United States”, said Scott Hoffman Black, executive director of the Xerces Society for Invertebrate Conservation and co-author of the paper. “Because logging and thinning cannot effectively alleviate the overriding effects of climate, it will do little or nothing to control these large-scale outbreaks.”

Logging and thinning can also inadvertently lead to heightened insect activity by removing large, dead trees that are often used as habitat by species that prey on bark beetles. Therefore, logging could prolong outbreaks because of a reduction in the beetles’ natural enemies, including both insects and bird species that feed on mountain pine beetles. Thinning or logging to control bark beetles can also have adverse consequences for wildlife and water quality, if roads are used to implement these logging projects.   

“The roads needed to implement large-scale thinning or logging can have extremely adverse impacts on fish and other aquatic life and fragment forests, negatively affecting wildlife such as Colorado’s blue-ribbon trout streams,” said Barry R. Noon, a professor in the Department of Fish, Wildlife, and Conservation Biology at Colorado State University.   

The authors recommend that instead of implementing large-scale logging projects priority be given to removing hazardous trees, which were killed by fire or insects and that might fall across roads or in campgrounds in areas of high-human use to limit damages and potential loss of life. Moreover, the report indicates that concentrating fuel reduction measures in the immediate vicinity of homes is the best way of reducing existing and future risks of fire. “Given our limited resources, focusing fuel reduction treatments around homes and communities rather than in remote beetle-affected forests would be more effective at reducing fire risk to those structures,” Kulakowski said.  

“Based on our findings, land managers and decision makers should exercise caution in jumping to a logging conclusion when dealing with bark beetle epidemics, as the costs to wildlife and clean water from logging outweigh any remedial benefit,” said Dominick A. DellaSala, chief scientist and president of the Geos Institute and co-author of the report.    


About the Authors  

Scott H. Black is the executive director of the Xerces Society for Invertebrate Conservation. He also serves as the Chair of the International Union for Conservation of Nature (IUCN) Butterfly Specialist Group and as a member of the IUCN Invertebrate Conservation Subcommittee. He has a Master of Science degree from the Graduate Degree Program in Ecology, through the College of Agricultural Sciences at Colorado State University. Scott has authored or co-authored more than 100 scientific and popular publications two books and dozens of technical reports on land management issues. Scott received the 2011 Colorado State University College of Agricultural Sciences Honor Alumnus Award.  

Dominik Kulakowski is an assistant professor of geography and biology at Clark University in Worcester, MA. For close to fifteen years, Kulakowski’s research has focused on how outbreaks and fires interact, as well as how climate affects these and other forest disturbances. He has published numerous scientific papers on interactions among disturbances, as well as on other topics dealing with forests of the Rocky Mountains and other mountain ecosystems.  

Barry R. Noon is a professor in the Department of Fish, Wildlife, and Conservation Biology at Colorado State University in Fort Collins, CO. He has conducted research on the effects of land management practices on wildlife populations for the past 36 years. During this period, he has published over 100 scientific papers and co-authored four book-length reports to the federal government on the sustainable management of public lands. For 11 years, he directed a Forest Service Research Lab in the Pacific Northwest (USA) and served for a year as chief scientist of the National Biological Service, Department of the Interior during the administration of President Clinton.  

Dominick A. DellaSala is the chief scientist and president of the Geos Institute in Ashland, OR, and president of the Society for Conservation Biology, North America Section. He is an international author of over 150 technical publications, including Temperate and Boreal Rainforests of the World: Ecology and Conservation (, acknowledged for “outstanding academic excellence” by Choice magazine (2012). Dominick has received conservation leadership awards from World Wildlife Fund (2000, 2004) and Wilburforce Foundation (2006).    


The following photographs can be obtained from Forestry Images at the URLs given.  

Mountain pine beetle (Dendroctonus ponderosae); adult.
Credit: Whitney Cranshaw, Colorado State University,  

Mountain pine beetle (Dendroctonus ponderosae); dead adult “pitched out” of hole by tree.
Credit: Whitney Cranshaw, Colorado State University,

Damage caused to lodgepole pines (Pinus contorta) at Rabbit Ear’s pass, Colorado, by mountain pine beetle (Dendroctonus ponderosae).
Credit: Whitney Cranshaw, Colorado State University,

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