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Multicentury, regional-scale patterns of western spruce budworm outbreaks

Thomas W. Swetnam, Ann M. Lynch
Summary - what did the authors do and why?

The authors reconstructed spruce budworm infestations using tree ring chronologies from the year 1690 to present and examined the potential relationships between historic spruce budworm infestations and human land use changes and climate variation.

Publication findings:

Increased tree densities and a shift toward fire-intolerant white fir in the understory due to fire suppression have impacted the timing of and the response of forest stands to infestations to some degree. The authors explain that white fir is more susceptible to mortality from spruce budworm, and increased mortality can lead to increased fire intensity. Regional outbreaks of spruce budworm were directly related to spring precipitation amount.

Fire and Ecosystem Effects Linkages

How do fire frequency, rotation, and return interval relate to species composition, non-natives, and structure?

Increased tree densities and a shift toward fire-intolerant white fir in the understory due to fire suppression have impacted the timing of and the response of forest stands to infestations to some degree. The authors explain that white fir is more susceptible to mortality from spruce budworm, and increased mortality can lead to increased fire intensity. Regional outbreaks of spruce budworm were directly related to spring precipitation amount.