Fires and pests
Across Canada, 9,000 to 12,000 forest fires occur annually, burning 2 to 7 million hectares. Wildfire is an inescapable aspect of the forest cycle, periodically removing overmature trees to clear the way for vigorous new growth. Many plants flourish in direct sunlight and the mineral-rich soil left by fire.
In the Boreal Shield, fire benefits poplar and birch, which spread seeds widely after a conflagration. Although most fires result from human carelessness — an untended campfire or a smoldering cigarette — 85 percent of the forest area burned annually is caused by lightning strikes. In built-up areas, fire suppression is essential to protect property and commercial timber stands. Firefighting may involve clearing fire lines and trenches to halt the fire, or using airplanes to douse a blaze with water.
Insect infestation is also a major forest menace. Spruce budworm, the dominant infestation of the Boreal Shield, takes hold in about 10 million hectares annually. According to some estimates, insects cause nine times more damage than fire.
A slide show of four images of people fighting forest fires.