In places where oxygen is limited, such as inside trunks or roots growing underground, fires can burn for days. Sometimes these smoldering fires, which are smoky but burning, can suddenly burst in hot wind conditions. This is one of the ways new fires can start. For this reason, it’s important to completely put out any fire (such as a bonfire) when you leave it.
You need some sort of heat to start a bushfire.
Sometimes the heat comes from lightning striking a dry area of plants. Sometimes, albeit less frequently, it results from the sparks that can occur when one stone falls on another and is scratched.
However, unfortunately, most fires are caused by humans. Sometimes people start fires on purpose, but most of the time it’s accidental.
For example, a person may accidentally let a small fire get out of control. Unexpected sparks from machinery, electrical systems and power lines can also cause fires.
Ignition control, where heat can start a fire, is an important part of reducing fires. This is why we sometimes have total fire bans in some places on hot and windy days. A total fire ban means that no one can start a fire in that area, not even a small bonfire.
Plants provide fuel for fires. Dry grass and litter are more prone to burning. Green leaves usually don’t burn easily because they contain water. But if the fire is very strong and it’s a dry and windy day, even the green leaves can burn. Under the most extreme conditions, entire tree crowns are burned in what are known as “canopy fires”.
Some plants burn more easily than others; some (such as succulents) are quite difficult to burn and others (such as eucalyptus) burn very easily.
The more fuel there is to burn the fire, the bigger the fire. This is why fire makers try to reduce the amount of fuel by removing dead plants or carefully burning a small number of plants (when it’s safe to do so) so that it doesn’t start a big fire later.
We need forest fires
Some people want to believe that fires can be completely eliminated from the environment. But this is a very bad idea, because fires are part of the natural environment. Fires have occurred since plants colonized the earth’s surface more than 400 million years ago.
The bigger question is how to best manage fires and learn to live with them, so that our homes and places we appreciate are not destroyed.
We must prevent fires by managing the amount of fuel and reducing the possibility of ignition. It is as important as fighting fires by putting them out.
Aborigines have learned to cope with forest fires by cleverly lighting fires to reduce the amount of fuel and create habitat for wildlife. As fires become more common and intense due to climate change, the challenge in the 21st century is to relearn these lessons from traditional Australian landowners.