Climate Change in the Pacific Region
Pacific Region


Pests in Pacific Northwest Forested Systems

The increased disturbance in forests from insects and other pathogens are occurring more rapidly and dramatically than imagined a decade ago. Understanding how these disturbances are influenced by climate change is therefore critical for quantifying and projecting effects. (Kliejunas, 2011, and Vose et al., 2012)

Pine beetle occurrence in the West is the most significant of these threats.  Populations have increased substantially and will likely continue to increase in a warmer climate along with other forest pathogens.  Some pine beetle broods have increased from one to two generations per year due to warming (Mitton and Ferrenberg, 2012).  Drought also increases tree vulnerability to mountain pine beetle.  Other pests and diseases, including sudden oak death, have been spreading northward from California into southwestern Oregon since the beginning of the 21st century.  In the case of sudden oak death, extreme precipitation events tend to infect more trees, which then become more vulnerable to mortality during droughts.  Generally, insects and diseases will expand northward in latitude, toward the coast and upward in elevation in a warming climate.  See Kliejunas et al. (2012) for a detailed risk assessment of forest diseases on forest ecosystems in the Western United States and Canada.







Learn more and read about the research that provided the information above by checking out the links below:

Kliejunas, John T. 2011. A risk assessment of climate change and the impact of forest diseases on forest ecosystems in the Western United States and Canada. Gen. Tech. Rep. PSW-GTR-236. Albany, CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest Research Station. 70 p.

Mitton, J.B., Ferrenberg S.M. 2012. Mountain Pine Beetle Develops an Unprecedented Summer Generation in Response to Climate Warming, The American Naturalist, Vol. 179, No. 5, pp. E163-E171
Vose, James M.; Peterson, David L.; Patel-Weynand, Toral, eds. 2012. Effects of climatic variability and change on forest ecosystems: a comprehensive science synthesis for the U.S. forest sector. Gen. Tech. Rep. PNW-GTR-870. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. 265 p.


Last updated: September 3, 2013

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