A typical savanna fire burning through the grass beneath the
trees. Photo: Jean-Charles
When we think of “bushfires” many people think of
the fierce wildfires that strike in the summer across southern
Australia. It may come as a surprise, therefore, that the largest
and most frequent fires in the continent occur in the southern
winter and spring – and occur in northern Australia. In terms
of sheer area, satellite images show that the vast majority of
landscapes burnt over the last several years have been in northern
Australia - as shown in the map below based on satellite imagery.
Over 98% of large bushfires occur outside the more densely
populated south-east and south-west of the country.
The northern savannas are primed for regular fire with vast
grassy landscapes that flourish during the wet season and then,
over months with very little rain, dry to a tinderbox. Although not
nearly as intense as southern bushfires, the problems these fires
are now creating for the people of the north are considerable,
whether for managing cattle stations or protecting fire-sensitive
plants and animals.
What types of fire occur in Australia's tropical savannas?
Regular, frequent fires in the far north
In the far north – the Kimberley, the Top End of the
Northern Territory and Cape York Peninsula – large fires
sweep across much of the landscape every year. The grasses that
cover the ground in these areas can grow as high as 3 metres as
they get plenty of sunshine and plenty of rain in the wet season
– usually over 800mm. Then they dry out rapidly, and can
carry fire throughout the dry season from shortly after the last
rains. These dry grasses, supplemented by litter (leaves, twigs and
bark) from the woodland trees, mostly Eucalyptus and
Corymbia species, provide most of the fuel for savanna
fires. They reach their most flammable state when the next wet
season is about to begin around October - November.
Dense stands of spear grass - which re-grows
every year - are common in the far north
These regular supplies of dry, grassy fuel for fire are one
reason why north Australia has such frequent fire, particularly in
the late dry season. The map below shows the frequency of fires
over the last several years as measured by satellite sensors. More
red patches equate to more frequent fires. Notice that the far
north is very frequently burnt - particularly the north-west of the
Northern Territory and the Kimberley and western Cape York
Fire frequencies in northern Australia 1997-2005
as detected by NOAA satellites (Landgate). The darker red areas
show areas burnt in most of the 9 years, the lighter pink areas are
burnt less frequently and the white areas unburnt by large
Less regular fires in grazed country further south and
Further inland, south and east in the tropical savannas, in the
more open landscapes of places like the Queensland gulf, less rain
falls in the wet season and there is often less grass as it is
grazed by cattle. This reduces the fuel available for fires.
Wildfires are often actively suppressed, and prescribed burning is
generally excluded so that pasture can be used as livestock forage
rather than as fuel for fire. In these landscapes fires are not as
common - as shown in the fire frequency map above.
Intensive cattle grazing reduces the grass
available to fuel fires
Extensive but not intense bushfires
If they are not burned, the grass and litter that fuel fires in
north Australia will build up over 3-5 years - however they will
not build up much further as it is continually being broken down by
active tropical decomposers like termites, fungi and bacteria. This
is in marked contrast to the situation in southern Australia's
eucalypt forests where fuel can continue building up for several
decades, preparing the ground for a massive conflagration.
As a result, even the most intense fires in the savannas are
considerably less severe than a raging bushfire in the south. Crown
fires in which the fire leaps from tree to tree, do not occur often
in the north. Nevertheless, late dry season savanna wildfires are
dangerous to people and property, and can cause severe damage to
plants and animal populations and, as described below, there is
evidence that these types of fire have increased in frequency in
recent years. Preventing them is a key objective of fire
While they are not very intense, fires in the north can spread
over vast areas with no roads or towns - across largely deserted
landscapes covered in grass. While fires in the cooler, early dry
season (April – June) are often small and patchy, once the
high temperatures and stronger winds of the late dry season
(October – December) combine with the now tinder-dry grasses
a wildfire can result and can spread and spread. In 2004 a fire in
the Tanami Desert covered around 60,000 square kilometres
–almost the size of Tasmania!
For more information see the separate section on Fire
Types , Fire Weather and Climate, Fuel
for Fire and Fire Behaviour in the menu on the left.
What are the main issues for managing fires in the
It appears that regular bushfire has long been a natural part of
landscapes across north Australia – many of the plants and
animals are adapted to some fires and evidence points to thousands
of years of regular burning by Aboriginal people. With traditional
practices, small patches of grassland were burned throughout the
year as people moved through the country. In the Top End and
northern Kimberley, many fires were lit in the early to mid-dry
season - although fires were also lit throughout the year. These
smaller and less intense fires of traditional practices maintain
more diverse habitats than large, late fires.
So why worry about bushfires in northern Australia?
Unfortunately there are increasing signs that the current patterns
of fire we are seeing in north Australia are new patterns –
and destructive ones.
For example, in the higher rainfall savanna woodlands of the far
north as much as half of the area is now burnt either every year or
every second year, typically late in the dry season (as shown in
the red areas in the map below). As these late fires are generally
intensely hot and extensive in area, they have the potential to
devastate populations of fire-sensitive native plants and animals,
to be costly and disruptive to pastoral operations, to pose a
threat to communities and property, while having implications for
greenhouse gas emissions.
Fire-affected areas as mapped by satellite in 1999 for northern
Australia. Blue areas show fire scars mapped before July 31 and the
red areas show those mapped from July 31 to the end of the
year. Source: WA Dept of Land Information
By contrast, in many of the
intensively grazed regions further inland to the south and east,
there is evidence that we are seeing new very low levels of burning
which are thought to be contributing to the unchecked growth and
increasing dominance of native trees and shrubs in once open
grasslands and woodlands. These "woody weeds" are causing problems
for beef cattle production and also degrade habitats for native
plants and animals.
Why has there been a change in fire patterns?
There is no simple answer,
but research points to a number of factors being involved in the
change in fire patterns.
Wildfires in empty landscapes
A range of evidence indicates
that for many thousands of years the landscapes of northern
Australia were home to many scattered Aboriginal communities who
used and manage fire for a number of purposes though much of the
year. Aboriginal people would have used fire for hunting, for
clearing country for walking through, for protecting important
sites and food resources such as fruit trees and for many other
reasons and consequently the country would have been subject to a
range of different fires throughout the year. This landscape of
patches of burnt and unburnt country made it difficult for any fire
to spread too far before it encountered a fire break of previously
Since European settlement,
however, the landscapes of northern Australia have become
increasingly emptied of people. Aboriginal people now live in
larger communities and do not extensively occupy, or in many cases
have access to, the landscapes they once managed. Cattle grazing
operations are increasingly automated requiring fewer people on
country. The end result is that much of the landscape is now empty
and vast areas have little fire until late in the dry season when
large amounts of fuel are primed for wildfire.
So are we seeing a more
natural situation similar to what it would have been like before
humans came to Australia with lightning driven fires? Not at all,
despite the rather deserted landscapes, the evidence from fire
agencies suggests that the overwhelming majority of bushfires
across north Australia are still started by people. Common cases
are where people light fires for fuel reduction burns, campfires or
clearing up country, but often the fires get away from them. Added
to this is the common observation that there now appear to be fewer
people who are very knowledgeable about managing fires. Because so
much land by the end of the dry season is covered with unburnt
fuel, these situations in which a small fire is lit can easily
become large wildfires that have nothing to stop them.
Reduced fire in cattle country
In the prime grazing lands,
in places like the Mitchell grass downs of Queensland and the
Barkly tablelands of the NT, grazing by cattle means there is less
grass around to burn. Graziers are also understandably reluctant to
light fires if they risk burning out the fodder they need to feed
their cattle. The end result in these landscapes is less fire over
the last century or so than there would have been during Aboriginal
occupation – and this appears to be contributing to a
“thickening” of woody shrubs and trees. This thickening
of vegetation is seen in the pair of photos below which shows the
area around Timber Creek in the grazing country of the NT. This
thickening is mostly seen in the riverine plains - other parts of
the landscape like the rocky escarpments are not thickening
Timber Creek, in the Victoria River District of
the NT in 1950 (Mettam Collection)
The same view in 1996 showing denser vegetation
next to the river and across the
Various other factors have been linked to changing fire patterns
in north Australia ranging from climate change to the spread of
introduced grasses. Of particular concern in the Northern Territory
is the spread of an introduced pasture grass, Andropogon
gayanus or gamba grass. Gamba grass is a perennial species of
African grass that is a useful pasture species and can be managed
if it is grazed by cattle. However gamba grass is now invading
savanna ecosystems throughout the Top End of the Northern Territory
and when it is not grazed it grows vigorously in tall stands that
provide fuel for intense fires. These fires in turn appear to be
helping the spread of gamba grass which is adept at invading burnt
A typically tall stand of gamba grass near
What are the impacts of the new fire patterns on
plants and animals?
Estimating the impact of the new fire patterns (also know as
fire "regimes") draws on a number of different sources of
knowledge: the traditional and observational knowledge of
Aboriginal people, the experience and practical knowledge of other
land managers and fire managers, and the knowledge that has come
from scientific research into fire management.
Various lines of evidence indicate that a number of different
species of plants and animals are declining in their numbers and
distributions as a result of changed fire regimes. These include
fire-sensitive plants such as cypress pine and groups such as the
grain-eating birds. See our section on fire and biodiversity.
The Gouldian finch is a seed-eating bird that is
thought to be threatened by, among other factors, changed fire
Two large-scale experiments, among many measuring the impact of
fire on savanna woodlands, have been conducted in the NT. Among
other findings these experiments have highlighted the importance
that the frequency of fire has on plants and animals. It is
important for the survival of some plant and animals species that
their savanna habitat is burnt not more than once every few years -
yet in many parts of the Top End of the NT, fire frequencies are
greater than this. See our section on fire experiments.
Fore more information see the section on Fire
Impacts on Biodiversity in the menu at the left.
What are the impacts of the new fire patterns on people and
Frequent and intense late dry season fires affect many different
aspects of the landscape, many of which are significant to
Aboriginal people: for example the occurrence of bush tucker. Thus
the new fire regimes can have a major impact on Aboriginal culture.
See the section on Aboriginal fire management.
Fire also has an impact on the city dweller and on tourists.
Smoke from fire drifts over towns and cities and can aggravate
respiratory complaints and the blackened landscapes left by fires
can often shock visitors to north Australia.
Northern fires can produce a great deal of smoke
which can affect air quality over towns and cities particularly in
the late dry season.
What are the impacts of the new fire patterns on agricultural
Other parts of north Australia have different fire management
issues. Evidence from savanna cattle runs, particularly in north
Queensland, suggests that a lack of burning in recent decades has
contributed to widespread land degradation. One of the reasons for
the absence of fire — in addition to a reluctance by many
graziers to burn their land — is that increased stocking
rates have reduced the availability of fuel. This has resulted in
reduced fresh pasture growth, deteriorating pasture species
composition, erosion, and a growing problem with woody weeds.
In most cases, fire is the only tool available to graziers for
tackling these shrubs that are taking over their pastures. While
much remains to be learnt about which fire regimes will be most
effective, it seems that intense fires generally have the biggest
impact. This raises difficult questions such as how to adjust
stocking to allow the fuel build-up needed to carry hot fires and
how to manage the fires safely.
In some situations, frequent low-intensity fires may be as
effective as less frequent intense fires. Where the choice exists,
this is likely to be the preferred alternative as it should be best
for pasture rejuvenation, reducing the hazards of wildfire and the
general health of the tropical savanna environment.
For more information see the sections on Fire
and People, and Fire and Indigenous Culture in the menu at
How can we better manage bushfires in north Australia?
People living in the savanna country have to recognise that
managing the country, to a large extent, means managing fire.
Wildfires can have devastating impacts on plants and animals as
well as endangering lives and property. But, as part of the natural
cycle in the savannas, fire also brings benefits. It promotes
'green pick' favoured by wildlife and stock, it regenerates food
plants such as yams, and creates habitat for various native
reptiles, mammals and birds.
A key part of managing fire will be using 'adaptive management',
in which we learn from our mistakes in a constructive way.
A number of other initiatives are worth pursuing:
- Developing better ways of monitoring fire so we can more
easily learn using adaptive management. The North
Australian Fire Information website is one monitoring
- Developing better fire management techniques to tackle
distinctive north Australian problems such as woody weed invasion
and the need to protect large fire-sensitive areas like the
sandstone escarpments from frequent fire.
- Supporting Aboriginal communities so they can build on
Indigenous Ecological Knowledge and put this into practice on their
country along with tools from western scientific knowledge.
- Provision of better education and other information resources
on fire management in north Australia. For example see the Tropical
Savanna CRC's Tropical Savanna Knowledge in Schools project.