Fire has been used across the Australian landscape as a vegetation management tool ever since the Aboriginal people first arrived. Whether it was used initially  to defend against lightning initiated wild fires, or to freshen up vegetation to entice native animals to an area, no one knows, but both reasons were and still are valid.

Thomas Mitchell wrote in 1848 in his "Journal of an expedition into the interior of Australia" the following description of the use of fire by Aborigines:

"Fire, grass and kangaroos, and human inhabitants , seem  all dependent on each other for their existence in Australia; for any one of those being wanting, the others could no longer continue. Fire is necessary to burn the grass, and form those open forests, in which we find the large forest kangaroo; the native applies that fire to the grass at certain seasons, in order that a young green crop may subsequently spring up, and so attract and enable him to kill or take the kangaroo with nets. In summer, the burning of the long grass also discloses vermin, birds nests, etc. on which the females and children, who chiefly burn the grass, feed. But for this simple process, the Australian woods had probably contained as thick a jungle as those of New Zealand or America, instead of the open forests in which the white men now find grass for their cattle, to the exclusion of the kangaroo."

Uses of fire

 To continue the carbon cycle and prevent plant death

As explained on the page about grazing and animal impact, plants need to have old leaf and stem removed at the end of the growing season each year to stay in top health. This leaf and stem might be removed during the growing season by grazing animals or it might be grazed off after the growing season has finished and the plant has dried off.
If this old plant material isn't removed the plant can be so shaded by its own old leaves that it is weakened or, in extreme circumstances, after several years of over-resting,  even killed. This is similar to a muscle in our bodies that withers away if it is not used.
 If old plant material isn't eaten, or trampled back into the ground, fire can be used instead to freshen up the plant. Burning, grazing or trampling also returns the carbon and other minerals from the dead leaves to the soil, where it can be used again by other plants and soil organisms.
With managing very old plant material, graziers like to use fire rather than grazing because stock can not survive by eating such low quality old feed.

To maintain grasslands and control trees

The constant use of fire by Aborigines before European settlement is believed to be the reason why the Australian landscape was not covered in thick forest when Europeans arrived here. Fires need to be very frequent to prevent trees and bushes from taking over and choking out pastures. Depending on the season and time of year that a patch of scrub is burned it can take between 2 to 8 years of annual burning to reduce tree numbers by 80%.(Noble - the Delicate & Noxious Scrub)  Some people speculate that more may have been needed than fire to keep tree numbers down. They suggest that some medium sized native mammals that are now rare or extinct (such as bettongs) may have grazed on  leaves from trees and shrubs that were reshooting after fire. This would have weakened the scrub and kept it in check with fewer fires needed. (see "The Delicate and Noxious Scrub")

On the left of this photo you can see dead wattle plants killed by a recent fire. The ghost gums have not been affected because of their size and because this area is only burnt very irregularly.
On the right grass is still long and rank and shrubs are still alive.

To maintain fire dependent species of plants

Many plants in Australia not only cope well with fire but actually require fire to reproduce. Banksias and Hakeas for example have woody seed pods that release seed only after they are burnt. Some tree seeds will not germinate unless they have been exposed to smoke. When planting these seeds today, people have developed a technique of watering them with water that has smoke particles mixed in it.

The photo on the left shows how
a fire (a year previous)
stimulates a mass germination
of wattle seedlings.

Dangers of fire use

Very large scale widespread fire kills animals

Fire is best used in small patches to minimise animal deaths.
If land is rested from the impact of human fires or domestic grazing stock then over a couple of years large amounts of combustible material builds up and then a lightning strike will cause a fire that can burn fiercely over large areas.
If large areas are burnt there is nowhere for animals to retreat to avoid the fire and after the fire there is no unburnt feed with-in easy reach for grass and leaf eaters. Predators may thrive temporarily as medium-sized animals have nowhere to take cover from their enemies.
The displacement  of Aborigines with their constant patch burning practices from the land and the failure to replace them quickly  with European managed grazing and patch burning may have been responsible for some extinctions.

Tim Flannery reports in his book "The Future Eaters" :
"The most critical work in this regard has been done by Dr.Ken Johnson and his colleagues at the Arid Zone Research Institute near Alice Springs, and Dave Gibson of Conservation and Land Management, Western Australia. They have been able to demonstrate that the extinction of middle-sized mammals occurred in areas where domestic stock never reached and where foxes are virtually unknown. They have also shown that  many extinctions happened as late as the 1960's and that they followed the departure of Aboriginal people from their tribal lands.

They suggest that Aboriginal firestick farming was an important factor in maintaining suitable conditions for the middle-sized mammal species. This was because Aborigines continually burned small patches of habitat. This created a mosaic of old, dense, unburnt vegetation which provided shelter, with newly burnt patches which were rich in newly sprouting leaves and shoots."   

Constant fire simplifies ecosystems and reduces biodiversity

Occasional fire can create greater diversity but frequent fires alone tend to simplify the ecosystem. A simplified ecosystem is one with less variety of plants and animals. A simplified ecosystem is more vulnerable to change. For example a pasture with only two species of grass in it may be completely wiped out if a flood hits the property and both species dislike being waterlogged. If the pasture had contained ten species of grass the chances would be greater that some of them could survive flooding and could feed stock and protect the soil until the other species recovered.

The following is a quote from Charles Darwin in his book "The Voyage of the Beagle" written in1845:

"The extreme uniformity of the vegetation is the most remarkable feature in the landscape of the greater part of New South Wales....In the whole country I scarcely saw a place with-out the marks of a fire; whether these had been more or less recent - whether the stumps were more or less black, was the greatest change which varied the uniformity, so wearisome to the traveller's eye."

According to Alan Savory, in his book "Holistic Management:  A New Framework for Decision Making",  test plots in both Zambia and Zimbabwe that were burned annually for over forty years were eventually dominated by one or two species of grass with self-drilling seeds adapted to charred , cracked and bare ground.

With European management fire has become a less regularly used management tool, being replaced to a large degree by grazing. Modern farming tends to simplify ecosystems through the use of technology and introduced plants rather than through overuse of fire.

Fire reduces plant litter and exposes soil surface

One of the main problems with the use of fire is that it burns up litter on the soil surface making it bare and therefore increasing the risk of erosion and soil capping (see information on soil surface capping on "tree pulling" page). Soil capping reduces water infiltration which means drier soils. This leads to more frequent drought conditions and at the same time larger amounts of water run off down creeks leading to more frequent floods. No wonder Australia which has been so reliant on fire is known as a land of "droughts and flooding rains".

Fire causes pollution and nutrient loss
When plants are burned not all of the nutrients contained in them are returned to the soil. Some nutrients escape directly into the atmosphere as smoke. Also because the litter cover has been reduced to ash there is nothing to stop the ash being easily washed down creeks with the first rains or blown away with wind.

Quoting again from "The Future Eaters":

"It has been estimated for example that for every hectare of grassland burned in the Katherine region of the Northern Territory, four-and-one-half kilograms of nitrogen is lost as nitrous oxide due to combustion . On Fraser Island it has been calculated that between 30 percent and 51 percent of sulphur is lost through volatilization from sclerophyll forest as a result of fire."

Again to quote from "Holistic Management: A New Framework for Decision Making":

"In 1994 scientists at Germany's Max Planck Institute found that disturbingly high levels of methyl bromide were also being produced by fires in Siberian forests, California chaparral, and South African savannas. The bromine in methyl bromine is potentially 50 times more efficient than the chlorine in chloroflurocarbons (CFCs) in destroying upper-level  atmospheric ozone."


In summary, fire is a necessary tool in the Australian landscape as an option for
Continuing the carbon cycle
Freshening up plant growth
Controlling tree thickening and regrowth
Maintaining fire dependent species
but it has many drawbacks including
Pollution and nutrient loss
Exposing the soil surface
Risking biodiversity loss from overuse
It may be wise to use an alternative whenever possible. For example good management of stock grazing and trampling can reduce the amount of burning needed to keep plants from being choked with old growth. It has been speculated that very short duration but intense grazing and trampling could kill tree seedlings and knock down shrubs and bushes which would reduce the amount of fire needed to control tree increase (see Grazing and animal Impact). Intensive management practices like this are new to the rang elands of Australia and difficult to implement but many graziers around Australia are beginning to consider and trial them.