OOS 4-1 - Direct and indirect effects of climate change on bark beetle outbreaks 

Monday, August 8, 2011: 1:30 PM
14, Austin Convention Center
Barbara Bentz, Rocky Mountain Research Station, USDA Forest Service, Logan, UT, James A. Powell, Mathematics and Statistics/Biology, Utah State University, Logan, UT, Jacques Régnière, Canadian Forest Service, Quebec, QC, Canada, Jeffrey A. Hicke, Department of Geography, University of Idaho, Moscow, ID and Stephen Seybold, USDA Forest Service, Pacific Southwest Research Station, Davis, CA

Outbreaks of native bark beetles are one of the most important disturbances in conifer ecosystems of the western US, and often result in widespread tree mortality that alters species composition, carbon sequestration and moisture transport properties. In recent decades, billions of coniferous trees across millions of hectares have been killed by native bark beetles in forests ranging from Mexico to Alaska.  Bark beetle population irruptions are directly sensitive to climate change components, and can also be influenced by landscape pattern that is created by antrhopogenic and/or natural disturbances. As with many poikilotherms, climate change can influence bark beetle population success through direct effects of temeprature on beetle phenology and survival, and indirectly through effects on host trees and associated microorganisms. Synhcronous adult emergence and life-cycle timing, ciritical strategies used by many bark beetle species to kill trees, are in large part dictated by several temperature-dependent physiological processes. Bark beetles are one of the few biological systems for which mechanistic models relating temperature and population demographics have been developed that also describe 'tipping point' behavior.


The role of temperature in bark beetle outbreaks is described.  Mechanistic models of bark beetle demographics, coupled with climate projections, are used to show changes in western coniferous landscapes throughout this century. Genetic variability among the widely distributed populations is described and potential for local adaptation, range expansion and extirpation are discussed.

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