In 1971, more than half of Alberta’s boreal forest by area was classified as regenerating or young, and a third was “immature.” By 2011 more than 40 per cent ha

In 1971, more than half of Alberta’s boreal forest by area was classified as regenerating or young, and a third was “immature.” By 2011 more than 40 per cent had become “mature” and more than 20 per cent “overmature,” a category all but absent earlier. This change is because of aggressive fire suppression. Before these major wildfire suppression efforts, boreal forests historically burned on an average cycle ranging from 50 to 200 years as a result of lightning and human-caused wildfires. In 2011, an out of control wild fire burned the town of Slave Lake and four nearby communities. A prescient 2012 Alberta report on that disaster blamed rigorous wildfire suppression, stating: " due to reduced wildfire activity, forests of Alberta are aging, which ultimately changes ecosystems and is beginning to increase the risk of large and potentially costly catastrophic wildfires. " http://wildfire.alberta.ca/wildfire-prevention-enforcement/wildfire-reviews/documents/FlatTopComplex-WildfireReviewCommittee-A-May18-2012.pdf http://wildfire.alberta.ca/wildfire-prevention-enforcement/w... The report, while 95 pages, makes for compelling and moving reading, even without the context of the ongoing disaster near Fort McMurray.