The Historical Pattern of Annual Burned Area in Canada

The record of national annual burned area from 1918 to 1986 is smoothed and presented as three kinds of running averages: simple arithmetic means, exponential means, and binomial means. The main features of the whole sequence are 1) a gradually decreasing trend for the first few decades followed by a sharp rise in the 1970s and early 1980s, and 2) a subsidiary rise and fall at a fairly regular interval of about ten years. The chance that these patterns are just statistical accidents is very low. Climatic cycles or trends that affect the weather with respect to forest fire are the most likely cause. Whatever the reasons, the fires of the 1970s and early 1980s have quite upset the pre-1970 trend of decreasing national annual burned area.