Important and complex spatial decisions, such as allocating land to development or conservationoriented goals, require information and tools to aid in understanding the inherent tradeoffs. They also require mechanisms for incorporating and documenting the value judgements of interest groups and decision makers. Multiple-criteria decision analysis (MCDA) is a family of techniques that aid decision makers in formally structuring multi-faceted decisions and evaluating the alternatives. It has been used for about two decades with geographic information systems (GIS) to analyse spatial problems. However, the variety and complexity of MCDA methods, with their varying terminologies, means that this rich set of tools is not easily accessible to the untrained. This paper provides background for GIS users, analysts and researchers to quickly get up to speed on MCDA, supporting the ultimate goal of making it more accessible to decision makers. A number of factors for describing MCDA problems and selecting methods are outlined then simplified into a decision tree, which organises an introduction of key methods. Approaches range from mathematical programming and heuristic algorithms for simultaneously optimising multiple goals, to more common single-objective techniques based on weighted addition of criteria values, attainment of criteria thresholds, or outranking of alternatives. There is substantial research that demonstrates ways to couple GIS with multi-criteria methods, and to adapt MCDA for use in spatially continuous problems. Increasing the accessibility of GIS-based MCDA provides new opportunities for researchers and practitioners, including web-based participation and advanced visualisation of decision processes.

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In Canada, recent fire seasons have demonstrated the threat of wildland fire in the Wildland-Human Interface (WHI) areas, where forest fuels intermingle with or abut housing, industry, and infrastructure. Although fire activity is expected to increase further in the coming decades as a result of climate change, no WHI-specific estimates of wildland fire exposure are currently available. This study combines spatial and demographic information sources to estimate the current and future wildland fire exposures, as reflected by fire return intervals (FRI) of WHI areas and populations across Canada. The WHI covers 17.3% of the forested area in Canada. Within the WHI, we found that 19.4% of the area currently experiences FRI ≤ 250 years but, by the end of the century, this could increase to 28.8% under RCP 2.6 and to 43.3% under RCP 8.5. Approximately 12.3% of the Canadian population currently live in the Wildland-Urban Interface (WUI), which includes 32.1% of the on-reserve First Nations population. Currently, 17.8% of the on-reserve WUI population is exposed to FRI ≤ 250 years, compared to only 4.7% of the remaining WUI population. By 2100, these proportions could reach 39.3% and 17.4% respectively, under the less optimistic climatic scenarios (RCP 8.5).