causes to a wild fire

• Forest fires are common in places around the world where climates are moist enough to allow the growth of trees and shrubs, but have extended dry, hot periods.
• What factors make wildfires burn more?

  • Wind strength
  • Humidity
  • Seasons
  • Space between fuels
  • Slope (topography)
• • Wind strength – this determines the rate of spread – e.g. the Black Saturday fires in Australia were driven by winds of up to 125 km/h (80mph). 
• Humidity – the drier it is, the longer the fire is likely to last and the more intense it is likely to be.
• Seasons – some locations experience drastic differences in temperature depending on the season it is – e.g. in Feb 2009 (Australia’s summer), temperatures had risen about 40 degrees C! 
• Space between fuels – denser vegetation is likely to lead to the continued spread of the fire. 
• Slope (topography) – fires on a 20 degree slope will advance at up to four times faster than on a flat surface! Have a look at the next slide…
• The ‘ladder effect’ describes the process of fires spreading from the forest floor to the canopy

  
• Pyrophytes = plants which have adapted to tolerate fire – surprisingly, fire acts favourably for some species
• Passive Pyrophytes = resist the effects of fire, particularly when it passes over quickly, and hence can out-compete less resistant plants which are damaged.
• Active Pyrophytes = have a similar competing advantage to passive pyrophytes, but they also contain volatile oils and hence encourage the incidence of fires which are beneficial to them
• Phyrophile = plants which require fire in order to complete their cycle of reproduction.
• Eucalyptus is packed full of VOCs (Volatile Organic Compounds) which enhance its flammability – this includes the bark and the leaves.
• Lightning strikes the Earth over 100,000 times a day. Of these, 10-20% cause a fire. 
• Forest fires move faster uphill than downhill! The steeper the slope, the faster the fire travels. If you live on a hill, you might want to leave your house if a wildfire is near.