Flagging

New methods will be developed, and existing methods will be improved in the area of risk assessment. We suggest that using the proposed framework for comparing tools will assist tool selection for a given situation and to improve understanding of the differences between tools in terms of precision, uncertainty, and resources required. In addition to ensuring that the set of tools forms a cohesive toolkit, it will also be important to improve the application of tools. That is, evaluating the applicability of a tool in a given situation needs to be easy, and usage of the method should be as straightforward and transparent as possible.

Although the examples we present focus on mountain pine beetle in lodgepole pine forests, the concepts underlying the risk-assessment methods and the classification gradient apply to other bark beetle species and forest systems. Susceptibility rating systems have been developed for MPB in ponderosa pine, Pinus ponderosa Laws. (Chojnacky and others 2000; Negron and Popp 2004) and whitebark pine, P. albicaulis Engelm. (Perkins and Roberts 2003). Dodds and others (2004) and Negron (1998) examined risk rating for Douglas-fir beetle (Dendroctonus pseudotsugae Hopk.). Susceptibility rating systems have been developed for spruce beetle (D. rufipennis Kby.) in Alaska (Reynolds and Holsten 1996). Connectivity analysis for risk assessment is not very common at present. We have ongoing work to explore risk of spruce beetle (across a large area of southwestern Yukon, Canada, using connectivity methods. In addition to susceptibility rating, statistical methods to examine spatial and temporal autocorrelation of environmental factors (Gumpertz and others 2000) and simulation-based approaches (Mawby and Gold 1984) have been applied to the southern pine beetle (D. frontalis Zimm.).

Applying methods in new systems presents a number of challenges and high levels of uncertainty. MPB have been expanding the northeastern limit of their range and are approaching boreal jack pine (P. banksiana Lamb.) forests in Alberta, Canada (H. Ono, pers. comm.). These changes increase uncertainty due both to the dynamic character of the changes and because little information is known on MPB—host interactions in these forests. Nonetheless, managers of these systems are faced with challenging decisions, and risk-rating systems can provide some insights. In conjunction with climatic suitability work (Taylor and others 2006), we have ongoing work to adapt and apply susceptibility and connectivity methods in the boreal forest of BC and Alberta, Canada.