Landscape Ecology

, Volume 30, Issue 6, pp 1075–1093

Geographically variable response of Dendroctonus ponderosae to winter warming in the western United States

  • Aaron S. Weed
  • Barbara J. Bentz
  • Matthew P. Ayres
  • Thomas P. Holmes
Research Article

DOI: 10.1007/s10980-015-0170-z

Cite this article as:
Weed, A.S., Bentz, B.J., Ayres, M.P. et al. Landscape Ecol (2015) 30: 1075. doi:10.1007/s10980-015-0170-z

Abstract

Context

Milder winters have contributed to recent outbreaks of Dendroctonus ponderosae in Canada, but have not been evaluated as a factor permitting concurrent outbreaks across its large range (ca.1500 × 1500 km) in the western United States (US).

Objectives

We examined the trend in minimum air temperatures in D. ponderosae habitats across the western US and assessed whether warming winters explained the occurrence of outbreaks using physiological and population models.

Methods

We used climate data to analyze the history of minimum air temperatures and reconstruct physiological effects of cold on D. ponderosae. We evaluated relations between winter temperatures and beetle abundance using aerial detection survey data.

Results

Extreme winter temperatures have warmed by about 4 °C since 1960 across the western US. At the broadest scale, D. ponderosae population dynamics between 1997 and 2010 were unrelated to variation in minimum temperatures, but relations between cold and D. ponderosae dynamics varied among regions. In the 11 coldest ecoregions, lethal winter temperatures have become less frequent since the 1980s and beetle-caused tree mortality increased—consistent with the climatic release hypothesis. However, in the 12 warmer regions, recent epidemics cannot be attributed to warming winters because earlier winters were not cold enough to kill D. ponderosae.

Conclusions

There has been pronounced warming of winter temperatures throughout the western US, and this has reduced previous constraints on D. ponderosae abundance in some regions. However, other considerations are necessary to understand the broad extent of recent D. ponderosae epidemics in the western US.

Keywords

Climate change Demography Mountain pine beetle Process-based model Bark beetles Pinus Cold tolerance 

Supplementary material

10980_2015_170_MOESM1_ESM.docx (11.6 mb)
Supplementary material 1 (DOCX 11927 kb)

Copyright information

© Springer Science+Business Media Dordrecht (outside the USA) 2015

Authors and Affiliations

  • Aaron S. Weed
    • 1
  • Barbara J. Bentz
    • 2
  • Matthew P. Ayres
    • 1
  • Thomas P. Holmes
    • 3
  1. 1.Department of Biological SciencesDartmouth CollegeHanoverUSA
  2. 2.USDA Forest ServiceRocky Mountain Research StationLoganUSA
  3. 3.USDA Forest ServiceSouthern Research StationResearch Triangle ParkUSA

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