Effects of spatial scale on the perception and assessment of risk of natural disturbance in forested ecosystems: Examples from Northeastern Oregon

Abstract

The perception and measurement of the risk of natural disturbances often varies depending on the spatial and temporal scales over which information is collected or analyzed. This can lead to conflicting conclusions about severity of current or past disturbances or the risk of future ones. Failure to look across scales also complicates local implementation of policies developed from broad-scale perceptions of risk because perception of risk is relative and depends on context. Methods that help policymakers, managers, and the public look across spatial and temporal scales can improve their understanding of the long-term dynamics of disturbances like wildfire and insect outbreaks. This capability provides a foundation for prioritizing restoration management activities, especially in forest types prone to frequent or severe disturbances. Although techniques for estimating risk over increasingly large spatial scales are becoming more widespread, the connection of risk assessments from broad to fine scales is not well established. We use a synthesis of five existing analyses to illustrate how scale affects the perception and interpretation of risk as information, models, and findings are stepped down from broad scale (interior Columbia basin) to mid scale (parts of a river basins) to fine scale (watersheds). We present results from the Interior Columbia Basin Ecosystem Management Project (ICBEMP) and the Interior Northwest Landscape Analysis System (INLAS) efforts that compare wildfire risk and other resource attributes. Our findings compare action and no-action alternatives to illustrate the use of multiple-scale “step-down” analysis for understanding the relation of broad-scale policy to the feasibility and impact of local management.