ABSTRACTAim  The conservation of biological and genetic diversity is a major goal of reserve systems at local, regional, and national levels. The International Union for the Conservation of Nature and Natural Resources suggests a 12% threshold (area basis) for adequate protection of biological and genetic diversity of a plant community. However, thresholds based on area may protect only a small portion of the total diversity if the locations are chosen without regard to the variation within the community. The objectives of this study were to demonstrate methods to apply a coarse‐filter approach for identifying gaps in the current reserve system of the Psuedotsuga menziesii (Douglas‐fir) forest type group based on current climatic conditions and a global climate change scenario.Location  Western United States.Method  We used an ecological envelope approach that was based on seven bioclimatic factors, two topographic factors, and two edaphic factors. Multivariate factor analysis was then used to reduce the envelope to two dimensions. The relative density of habitat and protected areas were identified in each part of the envelope based on the current climate and potential future climate. We used this information to identify gaps in the reserve system.Results  Although the protected areas occurred in all parts of the envelope, most existed in colder and drier areas. This was true for both the current climate and potential future climate.Main conclusion  To protect more of the ecological envelope, future conservation efforts would be most effective in western Oregon, north‐western Washington, and north‐western California.