Australia's changing forests

Australia's forests and woodlands have evolved over the past 60 million years. Following the breakup of the ancient land mass, Gondwana, Australia became hotter and drier and the once extensive areas of rainforest were displaced by hard-leafed vegetation adapted to withstand drier conditions.

Poor soils, drought and fire have all played a role in the evolution of Australia's distinctive and highly endemic vegetation. The incidence and spread of fire increased, initially with the onset of drier conditions and later with the arrival of humans over 40 000 years ago. Fire played a dominant role in the evolution of an enormous diversity of species within the genus Eucalyptus which now dominates our forest (Attiwell 1994).

The genus Eucalyptus has been described by Pyne (1992) as both the universal and ideal Australian, being 'versatile, tough, sardonic, contrary, self-mocking, with a deceptive complexity amid the appearance of massive homogeneity; an occupier of disturbed environments; a creature of fire'.

The regular burning practiced by Aborigines ceased with European settlement and was followed by an era of uncontrolled wildfires that were lit to protect settlements and farms, to improve access and to improve grazing.

From the available evidence Australia's present-day forest differ appreciably from those at the time of first European settlement. Ryan, Ryan, and Starr (1996) provide extracts from the early writing of explorers and settlers who describe the landscape as open woodland and forest with large, widely spaced trees, few woody shrubs and an abundance of grass.

It seems to me that its [Australia's] condition, when we took possession of it, was largely attributable to its aboriginal inhabitants ... the blackfellow was constantly setting fire to the grass and trees, both accidentally and systematically for hunting purposes. Living principally on wild roots and animals he tilled his land and cultivated his pastures with fire; and we shall not, perhaps, be far from the truth if we conclude that almost every part of New Holland was swept over by a fierce fire, on the average, once every five years ...

The omission of the annual periodic burning by natives, of grass and young saplings, has already produced in the open forest nearest Sydney, thick forests of young trees, where formerly a man might gallop without impediment, and see whole miles before him. Kangaroos are no longer seen there; the grass is choked by under wood; neither are there natives to burn the grass, nor is fire longer desirable there amongst the fences of the settler.

As remarkable as it seems, the altered fire regime of the last 200 years has seen rain forest and dense eucalypt establish on what in Banks' time was clearly open woodland.

The disappearance of perhaps as many as seventeen such species from the arid and semi-arid zones correlates with nothing but the removal of the traditional Aboriginal way of life in the area.