Fire has had a major role in shaping the forested landscapes of the American West. In recent decades, major efforts to quantify that role have been made, and characteristics of historic fire regimes have been defined: frequency, magnitude, variability, seasonality, synergism, and extent. Together, these characteristics also defined the historic landscape effects of fire in low-, moderate-, and high-severity fire regimes. Coarse-filter conservation strategies typically rely on knowledge of natural disturbance regimes to define appropriate forest structure goals, both at the stand and landscape scale, and these will differ by fire regime. Historic patch size increased across low- to high-severity spectrum, but edge was maximized in the moderate-severity fire regime. Fire exclusion in the 20th century has caused two major types of landscape change: loss of openings in once patchy landscapes, and imposition of high-severity landscape dynamics in areas where wildfire that escape suppression now burn. Effects of historical fire regimes may be in some cases either difficult to mimic or undesirable
