Climatic niche of the mountain pine beetle during its recent range expansion in North America

Authors: Dongmei Chen*, University of Oregon, Patrick Bartlein, University of Oregon, Daniel Gavin, University of Oregon, Christopher Bone, University of Victoria
Topics: Biogeography, Spatial Analysis & Modeling, Human-Environment Geography
Keywords: Climate space, climate change, mountain pine beetle, outbreak expansion, North America, spatial analysis
Session Type: Poster
Day: 4/4/2019
Start / End Time: 8:00 AM / 9:40 AM
Room: Lincoln 2, Marriott, Exhibition Level
Presentation File: Download

The mountain pine beetle (MPB) has expanded its geographical outbreak range, a pattern that has been broadly attributed to a warming climate. We test whether areas of outbreaks have been simply tracking the climate and the climatic niche of the beetle has remained static or whether the beetle range has expanded into a different climate space. We computed annual (1996-2015) bioclimatic variables that are known to be relevant for beetle survivorship using interpolated Climatic Research Unit data. Then we plotted climate space to show the climatic constraints for beetles’ expanding further in host range. We also used quantile regression combined with a bootstrap test to estimate the significant change in the thresholds of the beetle’s climate space during beetle range expansion and between the defined core regions and expanded regions. We found that minimum temperatures and the seasonal temperature variation are the most important variables constraining beetle climate space. The medians of bioclimatic variables (including constraint variables) have been stable. However, the lower quantiles of the minimum temperatures in the beetle outbreak range have slightly decreased and increased in higher quantiles, mirroring a regional increase in minimum temperature variability. Although the long-term climatic changes showed a warmer-trending climate and drier-trending summers in the current beetle outbreak range, the beetle populations might have also increased their thresholds to minimum temperatures. Our results suggest that the mountain pine beetle has been constrained in warmer space with lower temperature variation and also expanded its climate space to colder regions.

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