How do bushfires occur and progress?

For a bushfire to start there needs to be fuel, in the form of leaves and/or wood and a ignition or flame point.

This ignition can be caused either naturally by a lightning strike, spontaneous combustion or a deliberate/accidental flame.

Australian Bushfires are particularly severe as eucalyptus tree leaves contain large amounts of oil that act much like any oil and burn very fast and hot.

So how does a house burn down in a bushfire even if there are no trees are directly touching the house?


Three main reasons:

  • The water pressure at the local tap is too low for fire fighters to do anything.
  • Wind can send flying embers from the main fire which catch in gutters and ignite leaves or other materials around the house.
  • Gas lines leak and may explode.

Other  tips for protecting your House

  1. people should avoid living in or too close to the bush.
  2. avoid planting tall eucalypts near their houses
  3. reduce fuel load - get rid of leaves, fallen bark, dry wood around houses
  4. plant deciduous trees around the house rather than native trees
  5. ensure gutterings are clear of dry vegetation.

Thanks to Kath O'Brian for this

So, remember to keep your property clear of leaves if possible.

How do bush fires progress?

There are several major factors that affect the progress of a bushfire

  • high winds (provide more oxygen)
  • amount of fuel( eg leaves)
  • low humidity
  • high air temperature

All these contribute to the way a bushfire progresses. These factors then combine with the terrain. 


The kind of terrain, eg hills and slopes, for example fires tend to spread faster up sides of hills.

Additionally flying burning embers of a main fire front can set spot fires ahead. The fire basically basically leaps ahead of itself helped by the wind.


How are plants and animals affected by bushfires?

Plants, typically their leaves and bark, burn but many plants are adapted to regrow. Though it sometimes depends on how hot the fire is.

A detailed article on plant ecology and biodiveristy of how plants are affected, in some cases benefit from bushfires...Australian National Botanical Gardens

Animals have a much harder time. The only animal able to properly survive are wombats that dig under the ground. Many animals die from smoke or are burnt.