In black spruce forests in Alberta, past wildfires can have a protective effect. When firefighting is initiated at fire sizes ≤1 ha, the probability of the fire escaping is low during the initial 20–45 years of post-fire stand development, except under the most extreme fire weather conditions.

Other positive explanatory variables include the size of the fire at the initiation of firefighting and a relative rating of the expected rate of fire spread, the Initial Spread Index (ISI) of the Canadian Forest Fire Weather Index System.

Black spruce forests are characterised by high-intensity crown fires and early detection and containment of fires while they are small is crucial for averting progression to fire intensities that exceed suppression capabilities.
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In this study, we used logistic regression analysis to explore whether or not the time elapsed since prior wildfire in black spruce forests had an influence on the likelihood that initial attack efforts would fail to contain the fire.

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