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Climatic Drivers of Western Spruce Budworm Outbreak Dynamics in the Interior Pacific Northwest
Presented by Ms. Aquila FLOWER on 14 May 2013 from 11:55 to 12:15
Type: Oral Presentation
Session: Dendroecology I
Outbreaks of the western spruce budworm (WSB) often occur synchronously over broad regions of western North America. In spite of the ecological and economic significance of this species, the mechanisms controlling its population dynamics are still not fully understood. In this study, dendrochronological methods were used to reconstruct multi-century records of WSB outbreaks at thirteen sites along a transect running from central Oregon to western Montana. The reconstructions show that all thirteen sites experienced multiple WSB outbreaks over the last three centuries. Outbreaks were often synchronous across the entire transect. Comparison of the outbreak records with climate records revealed consistent relationships between moisture availability and outbreak dynamics. Climatic variability at broad spatial scales was also shown to be associated with the regional synchronicity of WSB outbreaks. Outbreak initiation at individual sites and the initiation of regionally synchronous outbreaks both tended to occur near the end of moderate droughts.