From John Woinarski, 1998 Summary Papers from the
North Australia Fire Management Workshop, March 24–25,
Darwin, eds. Tropical Savannas CRC.
The issues | Effects of changed fire
equilibrium |Unravelling impact of fire |Managing fire for
conservation |
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Golden-shouldered parrot: studies have revealed
the bird has an intricate relationship with fire
Photo: Darryn Storch
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Essentially, there are two questions:
- what species (or environments) are being disadvantaged by the
prevailing fire regimes?
- (how) can we mould those regimes to offer better protection for
these losers?
An intricate and relatively ordered fire regime imposed on
northern Australia over the period 50,000+ years before the present
to around 50 years ago, has undoubtedly sifted the biota, retaining
only those species and environments tolerant of that regime. Rapid
and substantial changes in burning practice over the course of this
century have upset the previous equilibrium, making conditions more
favourable for some species (and environments) and less favourable
for others. Depending upon the geographic scale and magnitude of
the shift, the disadvantaged species (and environments) face local
decline to regional extinction.
Describing and mapping the contemporary pattern of fires in
northern Australia is relatively straightforward, notwithstanding
the technological sophistication required. But how can these
patterns be translated to tell us of the ecological consequences?
Conceptually, it is such a simple thing to detect which species are
declining because of now inappropriate fire regimes. Practically it
is a far more complex problem. Compared to most other areas in the
world, there is very limited historical documentation of the
distribution and abundance of the biota in northern Australia.
Landscape-scale changes here have involved a complex interplay of
factors, so that disentangling the impacts of fire from those of,
say, pastoralism is difficult, and may be unhelpful (given the
sometimes synergistic effects). The impacts of fire upon any
element of biodiversity are also extremely variable, differing with
extent, timing, intensity and frequency.
For most species and many environments, the management of fire
for conservation of biodiversity is hampered by lack of knowledge.
There have been few long-term experimental studies capable of
revealing sustained responses to fire regimes. Most of these have
involved experimental plots which are too small to detect changes
for most vertebrates (the notable exception being CSIRO's
catchment-scale study at Kapalga); and/or the dead hand of
experimental protocol has led to the imposition of unrealistically
regimented fire treatments.
A few studies have chronicled long-term changes in the
distribution of particular environments through matching of a
chronological sequence of imagery and/or through comparison with
historical records. A few studies have focussed on individual
species (e.g. Callitris, golden-shouldered parrot, frilled lizard).
These studies have revealed some strong and intricate relationships
with fire, but the more general extension of these findings to
other species and environments remains very uncertain.
Lacking information (but not abandoning the need for more of
it), is it possible to work from general principles? Maintaining
biodiversity is largely about maximising environmental
heterogeneity. More than almost any other factor which can affect
landscape patchiness, fire is a flexible tool, and fire management
should aim to impose a gamut of regimes (other than the
unreasonably extreme) across most of the landscape, at an
appropriate scale. With a little winkling, this can be translated
into four guidelines:
- fires should be small.
- fires should be planned.
- fires should happen.
- fire regimes should be heterogeneous.
