• Severe weather events can cause pockets or large areas of forest to blowdown, which can result in some or all trees within an area to break off or uproot.
  • Blowdown events in Ontario usually range from 5 to 50 hectares in size, but can get as large as 500,000 hectares, particularly in the boreal forests of northern Ontario.
  • Other terms used include: windthrow, windblow and stem breakage.

Poplar forest damaged by severe weather

Damage characteristics

  • Some blowdown events level most or all of the trees in a stand, with the trees lying in the same direction on the ground.
  • This is common in spruce and jack pine stands in the boreal forest.
  • In poplar or mixed-wood stands, often only tops or portions of trees are damaged, breaking off near the crown.
  • Areas of blowdown become a fire hazard as the dead trees dry out.
  • Blowdown is often caused by a straight-lined wind storm that is referred to as a “derecho”.
  • The 2005 blowdown near Lac Seul in northwest Ontario was over half a million hectares in size.

Blowdown in Red Lake