Most Australian plants are not only very well
adapted to fire, in some cases they depend upon it for survival.
Eucalypt species are very fire resistant, and some even use the
heat from the fire as their cue to drop seed or germinate.
Our grasses are also well adapted to fire, and
regrow rapidly if burnt at the right time. Species like black
speargrass particularly so. Their seed burrows into cracks in the
soil, protecting it from fire, while the seeds of competing grasses
From Dr Peter O'Reagain Principal
I SPENT 10 years researching South African native pastures
before immigrating to Australia in 1995. The research taught me
fire is one of the cheapest and most effective management tools
available for pasture management.
However, the big challenge in our dry and variable environment
is to link burning with rainfall. Forecasting tools like the
Southern Oscillation Index (SOI) allow us to select years with a
good chance of a reasonably good season. But even then, it is
important never to burn too much in any one year. Also you need to
spell a paddock for as long to ensure regrowth. A burn followed by
a drought could mean a whole year with no pasture!
Out of Favour
Fire has unfortunately dropped out of favour. It is not applied
nearly enough, and where it is, applied incorrectly. Sometimes
people think burning is a waste of feed. In other cases, there is
very little fuel to burn, because of heavy stocking rates.
As a result, woody weeds such as rubbervine, currant bush and
chinee apple flourish. Many people have also noticed a thickening
of our native trees, reducing grass production. Pasture condition
has declined, and fire-tolerant species, such as black speargrass
are dying out.
But before burning, we should ask: "Why am I burning?" Is it to
control trees and woody weeds, or is it to remove dead grass and
'freshen up' the pasture? Hot Fires
This critical question determines how, and when, the fire will
be applied. If the aim is to control woody weeds, then the fire
must be very hot to ensure sufficient heat to kill the trees or
To achieve a 'hot' fire, there should be a lot of fuel
present-at least 2000 kg per hectare. Also, the fire needs to be
set when conditions are at their driest, preferably near the end of
the dry season when things are very dry.
The time of the day the fire is applied is also critical to get
a hot fire. Burning should be between 10am and 3pm when the
relative humidity is low, and the fuel is at its driest.
It is also important for the fire burn with the wind, to get a
'head fire' so the heat is carried up into the trees to cause the
most damage. Follow-up burns will almost always be required for
woody weeds. If, however, the intention is to remove old grass,
then the fire should be cool.
Cool fires literally just singe the dead leaves off the plant,
and should be lit early in the morning or late in the evening when
the relative humidity is high. These fires should also be "head
fires" and burn with the wind. This ensures the flame front passes
over the plants quickly, causing minimum damage to the
To avoid damaging grass, the grass must be dormant, usually in
the dry season. But this could even be in the middle of the wet
during a long dry spell, or just after the first rains before the
grass has started to grow fully. Also, burnt areas should not be
grazed until they have regrown sufficiently. If grazed too soon
after regrowing from a fire, grass can be seriously weakened and
die, leading to a decline in pasture condition and
So the basic rules are:
- Decide why you want to burn.
- Apply the appropriate fire under the right conditions.
- Give the pasture a chance to recover before grazing.
Long Paddock: Rainfall and Pasture Growth (Qld)
The Long Paddock website provides information about rainfall, pasture growth and curing rate maps from the 1890s to the present.
Qld Dept. Natural Resources & Water: Silo
The NRW SILO website provides meteorological data for biophysical and landscape modelling. The up-to-date, Australia-wide data provided is continuous (no missing data) and is also:
- point and spatial
- historical length
- daily time-step
SILO: Agricultural and Meterological Information
The SILO web site provides climate outlook information across Australia. Some services are provided on a user-pays basis.