Wildfires

• What is a wildfire?

  a large uncontrollable fire that quickly spreads through vegetation
• What is a materials flash point?

  temperature that something will burst into flames
• What is woods flash point?

  300 degrees
• What is the temporal and spatial distribution of wildfires?

  • Rare in areas so dry that little vegetation grows and where rainfall is high
  • wetter season for vegetation to grow followed by prolonged dry season
  • continental interiors
  • common in boreal forests of Canada
• Describe ground fires

  • beneath surface litter - peat
  • 540 degrees
  • smoulder
  • long
• Describe surface fires

  • dry
  • in litter layer
  • can be controlled
  • organic
  • 900 degrees
• Describe crown fires

  • little control
  • quick
  • in canopy
  • 1100 degrees
  • needs strong winds, steep slopes and heavy fuel load
• What is the ladder effect?

  fuel that can carry fire burning in low vegetation to taller vegetation
• How does vegetation type favour wildfires?

  • thick undergrowth or closely spaced trees allow fire to travel easily
  • grassland fires rarely produce the same intensity and degree of threat as forest fires
  • moisture content
  • eucalyptus trees shed strips of bark which help fire spread
  • oil - eucalyptus in Australia and pine in boreal forests