by Michael Totten

Created on: October 07, 2008

Because of its long isolation from the rest of the world, Australia has evolved one of its most unique biospheres, with a biodiversity of animal and plant species seen nowhere else on earth. Even though pre-European human activity has been linked to the extinction of such creatures as the thylacine, the Aborigines of Australia had achieved a dynamic balance with their ecosphere long before the arrival of the first European boats on Australian shores. Some forty thousand years after the Aborigines had become an integral part of the Australian ecosystem, Dutch and then British explorers began to chart its coastline. On 1788, Britain established its first settlement and penal colony at Port Jackson, in what is now New South Wales.

British colonial interests saw the Australian continent as a resource to be exploited, importing British agrarian policies into a new ecosystem. Australian grassland became British pastureland, but the grass fires which had built and maintained that pasture by removing shrubs and continually encouraging new growth were seen as threats by British transportees and other colonists, who, unlike the nomadic Aborigines, were tied to their individual plots of land. Their efforts to suppress the natural cycle of fires led to an increasing suppression of pastureland by heavy brush, which in turn increased the intensity of those fires which did erupt. Forests were felled for their timber and to open new fields to agriculture. These coastal boreal ecosystems were pushed ever further into the outback, where they came into conflict with other, preexisting ecosystems already adapted to the local conditions. The introduction of large-scale irrigation allowed agriculture to push into ever drier regions, while at the same time increasing the salinity of the surrounding soils. These rapidly changing environments destroyed many species populations and seriously stressed others.

What tipped the balance for many was the additional introduction of alien species, including 56 vertebrate species, which could have no natural predators or other check on their spread. Marsupials especially tend to be vulnerable when competing with mammals for a comparable ecological niche, which elsewhere in the world has resulted in the large-scale extinction of most marsupial species. In Australia, almost every ecological niche is filled by marsupials which elsewhere is filled by mammals.

When British settlers brought their mammalian livestock with them, along with some unintentional

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