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Title: The effect of warmer winters on the demography of an outbreak insect is hidden by intraspecific competition

Warmer climates are predicted to increase bark beetle outbreak frequency, severity, and range. Even in favorable climates, however, outbreaks can decelerate due to resource limitation, which necessitates the inclusion of competition for limited resources in analyses of climatic effects on populations. We evaluated several hypotheses of how climate impacts mountain pine beetle reproduction using an extensive 9-year dataset, in which nearly 10,000 trees were sampled across a region of approximately 90,000 km 2, that was recently invaded by the mountain pine beetle in Alberta, Canada. Our analysis supports the hypothesis of a positive effect of warmer winter temperatures on mountain pine beetle overwinter survival and provides evidence that the increasing trend in minimum winter temperatures over time in North America is an important driver of increased mountain pine beetle reproduction across the region. Although we demonstrate a consistent effect of warmer minimum winter temperatures on mountain pine beetle reproductive rates that is evident at the landscape and regional scales, this effect is overwhelmed by the effect of competition for resources within trees at the site level. Our results suggest that detection of the effects of a warming climate on bark beetle populations at small spatial scales may be difficult withoutmore » accounting for negative density dependence due to competition for resources.« less
ORCiD logo [1] ;  [2] ;  [3] ;  [4] ;  [5] ;  [6] ;  [1] ;  [1]
  1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  2. Utah State Univ., Logan, UT (United States). Dept. of Mathematics and Statistics
  3. Univ. of Minnesota, Minneapolis, MN (United States). Dept. of Entomology
  4. Alberta Agriculture and Forestry, Edmonton, AB (Canada). Forestry Division
  5. Natural Resources Canada, Victoria, BC (Canada). Canadian Forest Service
  6. Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Publication Date:
Report Number(s):
LA-UR-17-30013; PNNL-SA-133988
Journal ID: ISSN 1354-1013
Grant/Contract Number:
AC52-06NA25396; AC05-76RL01830; XWPB00 CPF8GMAN
Published Article
Journal Name:
Global Change Biology
Additional Journal Information:
Journal Name: Global Change Biology; Journal ID: ISSN 1354-1013
Research Org:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23); LANL Laboratory Directed Research and Development (LDRD) Program; PNNL Laboratory Directed Research and Development (LDRD) Program
Country of Publication:
United States
54 ENVIRONMENTAL SCIENCES; bark beetle; climate change; density dependence; dynamics; insect; outbreak; population ecology
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1439363; OSTI ID: 1441314; OSTI ID: 1457766