One of the most complex and contentious issues in Australian ecology
concerns the environmental impact of
Aboriginal landscape burning. This issue is not only important for the
development of a comprehensive
understanding of the dynamics and evolution of the Australian biota, but
is central to the formulation of
appropriate strategies for the conservation of the nation's biodiversity.
Ethnographic evidence leaves little doubt
that Aboriginal burning played a central role in the maintenance of the
landscapes subsequently colonized by
Europeans. Both 19th century European colonists and anthropologists in
the 20th century documented the
indispensability of fire as a tool in traditional Aboriginal economies,
which have aptly been described as ‘fire-stick
farming’. Aborigines used fire to achieve short-term outcomes such
as providing favourable habitats for
herbivores or increasing the local abundance of food plants, but it is
not clear whether or not Aborigines had a
predictive ecological knowledge of the long-term consequences of their
use of fire. A large body of ecological
evidence suggests that Aboriginal burning resulted in substantial changes
in the geographic range and
demographic structure of many vegetation types. Aboriginal burning was
important in creating habitat mosaics
that favoured the abundance of some mammal species and in the maintenance
of infrequently burnt habitats upon
which the survival of specialized fauna depends. Aboriginal fire regimes
were probably critical for the maintenance
of at least one species of tree (Callitris intratropica) in the
monsoon tropics.
The question of the original impact of humans on the Australian environment
is fundamentally speculative
because of vague, disputed time frames proposed for the waves of colonization
and shifting settlement patterns of
Aborigines in the late Quaternary period. There is an inherent circular
argument concerning the cause and effect
of climate change, vegetation change, and burning through the late Quaternary.
Charcoal and pollen evidence from
long sedimentary cores is ambiguous and cannot be used to demonstrate unequivocally
the initial impact of
Aboriginal people on the landscapes of Pleistocene Australia. The sparse
available evidence does not support the
hypotheses that Aboriginal burning was primarily responsible for the extinction
of Pleistocene megafauna; was
critical for the maintenance of habitats of small mammals that have become
extinct following European
colonization; initiated widespread accelerated soil erosion rates in either
the Pleistocene or Holocene; or forced
the evolutionary diversification of the Australian biota. Burning may have
caused the extinction of some fire-sensitive
species of plants and animals dependent upon infrequently burnt habitats,
and it must have maintained
structurally open vegetation such as grasslands and also extended the range
of fire-adapted species, such as
Eucalyptus, into environments climatically suitable for rain forest.
Palaeoecological research concerning prior
impacts of Aborigines must give way to focused studies of the role of different
anthropogenic fire regimes in
contemporary ecosystems that have not been destroyed by European colonization.
Such research is crucial for
comprehending the role of Aboriginal burning in the maintenance of Australia's
unique, rich biodiversity.