Fire plays an important role in restoring health to our forests and maintains biodiversity by creating a mosaic of forest stands of varying age structure. Forests in the Montane and Subalpine ecoregions have become overgrown and dense. Fire history studies have suggested that fire use by First Nations was common, although probably not ubiquitous. The removal of most human caused fires by the beginning of the 20th century along with fire suppression and landscape fragmentation since that time have greatly decreased area burned and modified fire regimes. The Area Burned Condition Class (ABCC) measure has been designed to be evaluated and reported as a condition monitoring measure within the Parks Canada Agency National Ecological Integrity (EI) Monitoring program in all national parks with fire-dependent vegetation. This measure is based closely on the fire cycle concept and assesses the degree of departure (Area Burned Difference) from historic or reference area burned levels within a park.