AffluenceAustralia: A Unique Continent
What's so special about this place?
The general poverty of Australian soils is due to lack of volcanic or glacial activity required to renew soil. the most recent volcanic activity was ten million years ago in the South East portion of the continent (which is relatively fertile). Australia has few permanent rivers. Extensive manipulation of its fragile river systems for irrigation, combined with massive deforestation, has accelerated soil degradation and contributed to extensive salinisation and creeping desertification. The 'islands' of comparative fertility are also the preferred habitat of most Australian fauna, which must compete for these areas with the rapidly growing, highly urbanised human population. What are some characteristics thought to be typical of Australian ecosystems?Dr Tim Flannery, of the Australian Museum, wrote about the following special characteristics of Australian and other 'Oceania' ecosystems in a terrific book called The Future Eaters (Reed Books, 1994). He won the Australian scientific "Eureka Prize" for this book. It is now widely believed that Australian animal and plantlife have adapted to prevailing conditions over the past 40 million years or so, using some of the following typical characteristics: They grow and reproduce very slowly. The number of big warm blooded carnivores at the top of the food chain is very small and those animals tend to be little. The biggest carnivores tend to be cold blooded, like lizards and crocodiles, which have lesser energy requirements. Metabolisms tend to be slow to conserve energy use. Diversity of species is extremely high with a correspondingly minutely adjusted ecosystem incorporating highly specialised characteristics and co-operative behaviours. Some interesting adaptations amongst plants include the fact that Australia possesses the largest variety of carnivorous plants in the world. It is thought that these plants supplement our notoriously nitrogen deficient soil by obtaining nitrogen from live prey. "...poor soils and the El Nino Southern Oscillation cycle have put a premium upon retaining and rapidly recycling nutrients. This can be done most efficiently by various species developing intimate relationships. Species which belong to an ecosystem which does not have such efficient nutrient recycling are rapidly selected against. Those which co-operate in large, complex systems to maximise the availability of nutrients - such as corals, fish and other creatures of the Great Barrier Reef, or the plants and animals of the Australian rainforests - have a competitive edge..." "The highly co-evolved ecosystems that have resulted from this evolutionary pressure are extraordinarily good at maximising whatever nutrients are available ... [but they are] extremely fragile." What is the reason for Europe's famously fertile soil?Europe is mountainous and fertile with predictable seasonal patterns. Only 8000 years ago the last glaciers of the most recent European ice age melted, leaving a rich legacy of countless millions of tons of pulverised rock, releasing nutrients and laying down deep and fertile soils. What are the differences between European and Australasian ecosystems?Consider the difference between European and Australasian ecosystems. The plants and animals that survived in the post ice age European environment were those that could survive close to human settlement and that bred fast, travelled far, were not highly specialised, and could quickly take over new territory and out breed, outstrip and outhunt less consumeristic species. These animals and plants didn't need to worry about conserving energy because there was no nutrient shortage. The plant species we call "weeds" all have such characteristics. So does the fox, the rabbit, the rat and European man, to give just a few examples. "Europe is only slightly larger than Australia, but is home to
over 660 million people, compared with Australia's 18 million.
Despite [Europe's] enormous human population, it still has the
resources needed to support 27 species of mammalian carnivores,
including two species of bears, which are the largest land based
carnivores of all. [But] the warm blooded carnivore assemblage of
Australia is pitiful by comparison, the largest of its few
species (most now extinct) weighing a mere 60kg."
|
