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Unformatted text preview: 223 Effects of Climate Change on Range Expansion by the Mountain Pine Beetle in British Columbia Allan L. Carroll, Steve W. Taylor, Jacques Rgnire * and Les Safranyik Canadian Forest Service, Paci f c Forestry Centre, 506 W. Burnside Rd., Victoria, BC V8Z 1M5 * Canadian Forest Service, Laurentian Forestry Centre, PO Box 3800, Sainte Foy, QC G1V 4C7 Abstract The current latitudinal and elevational range of mountain pine beetle is not limited by available hosts. Instead, its potential to expand north and east has been restricted by climatic conditions unfavorable for brood development. We combined a model of the impact of climatic conditions on the establishment and persistence of mountain pine beetle populations with a spatially explicit, climate-driven simulation tool. Historic weather records were used to produce maps of the distribution of past climatically suitable habitats for mountain pine beetles in British Columbia. Overlays of annual mountain pine beetle occurrence on these maps were used to determine if the beetle has expanded its range in recent years due to changing climate. An examination of the distribution of climatically suitable habitats in 10- year increments derived from climate normals (1921-1950 to 1971-2000) clearly shows an increase in the range of benign habitats. Furthermore, an increase (at an increasing rate) in the number of infestations since 1970 in formerly climatically unsuitable habitats indicates that mountain pine beetle populations have expanded into these new areas. Given the rapid colonization by mountain pine beetles of former climatically unsuitable areas during the last several decades, continued warming in western North America associated with climate change will allow the beetle to further expand its range northward, eastward and toward higher elevations. Introduction Every aspect of an insects life cycle is dependent upon temperature because they are cold blooded. Therefore, these organisms should respond quickly to changing climate by shifting their geographical distribution and population behaviour to take advantage of new climatically benign environments. Rapid ecological and genetic adaptation by insects in response to global warming has already been documented in Europe (Thomas et al. 2001). However, for North America, despite the development of several models predicting climate change impacts (e.g., Logan and Powell 2001), there is little empirical evidence that global warming has affected insect populations. In long-lived ecosystems such as forests, insects are often primary disturbance agents (e.g., Dale et al. 2001; Logan et al. 2003). The mountain pine beetle, Dendroctonus ponderosae (Hopkins), is one of the most Mountain Pine Beetle Symposium: Challenges and Solutions. October 30-31, 2003, Kelowna, British Columbia....
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This note was uploaded on 12/25/2009 for the course ENV S 100 taught by Professor Staff during the Fall '08 term at UCSB.
- Fall '08
- The Land