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Individual Highlight

Elevational Shifts in Thermal Suitability for Mountain Pine Beetle in a Changing Climate

Photo of Mountain pine beetle-caused whitebark pine mortality near Black Butte, MT. Barbara Bentz, U.S. Department of Agriculture Forest Service.Mountain pine beetle-caused whitebark pine mortality near Black Butte, MT. Barbara Bentz, U.S. Department of Agriculture Forest Service.Snapshot : By the end of the century, climate change-driven optimal temperature suitability for mountain pine beetle population growth is predicted to be greatest at the lowest and highest elevations.

Principal Investigators(s) :
Bentz, Barbara J.  
Research Location : Idaho, Montana, Wyoming, Utah
Research Station : Rocky Mountain Research Station (RMRS)
Year : 2016
Highlight ID : 1172

Summary

Future forests are being shaped by changing climate and disturbances. Climate change is causing large scale forest declines globally, in addition to distributional shifts of many tree species. Because environmental cues dictate insect seasonality and population success, climate change is also influencing tree killing bark beetles. The mountain pine beetle is a major disturbance in pine forests of the western U.S. Using a temperature-driven phenology-based model describing mountain pine beetle population growth, coupled with Global Climate Models, Forest Service scientists predicted future elevational shifts in suitability for pine forests in the U.S. Department of Agriculture Forest Service Northern Region. Model predictions suggest that by the end of the century, the greatest mountain pine beetle-caused tree mortality will occur in low- and high-elevation forests where thermal suitability for mountain pine beetle population growth will be most optimal. Model results can facilitate predictions of future forest vulnerability to changing climate. Using a mechanistic, phenology-based demographic model driven by downscaled daily temperature data the scientists describe recent and future spatial and temporal thermal suitability for mountain pine beetle population growth in a topographically complex region.

Trends in model-predicted growth rates among Global Climate Models were similar and suggest that, relative to future trends, mountain pine beetle population growth within the past 60 years was most optimal at middle elevations and least optimal at the lowest and highest elevations. This trend aligns with observed mountain pine beetle-caused tree mortality that was greatest at middle elevations between 1997 and 2013, as estimated from Aerial Detection Surveys; however, thermal suitability for optimal phenological synchrony was predicted to shift in recent years, and by the end of the century the best thermal habitats for mountain pine beetle will be at the lowest and highest elevations. Mechanistic demographic models are valuable tools for modeling future thermal regimes that may be both beneficial and maladaptive for mountain pine beetle population growth and subsequent tree mortality.

Forest Service Partners

External Partners

 
  • Jacob Duncan, Utah State University
  • Jim Powell, Utah State University

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