Our natural environment
Australia is the sixth largest country in the world. Its ocean territory is the world's third largest, spanning three oceans and covering around 12 million square kilometres.
Nearly seven million square kilometres, or 91 per cent of Australia, is covered by native vegetation. Although this figure may seem high, many of Australia's desert landscapes are covered by native plants such as saltbush, albeit sparsely.
For tens of thousands of years, the lives and sense of cultural identity of Indigenous Australians were inextricably linked to the land, its forms, flora and fauna. Today, the identity of all Australians is shaped by a relationship with the natural environment.
Australia is one of the most urbanised and coast-dwelling populations in the world. More than 80 per cent of Australians live within 100 kilometres of the coast.
Australia has some of the oldest land surface on earth and while rich in biodiversity its soils and seas are among the most nutrient poor and unproductive in the world. This is due mainly to the country's geological stability, which is a major feature of the Australian land mass, and is characterised by, among other things, a lack of significant seismic activity.
Only six per cent of the Australian landmass is arable. Large volumes of water are required from both surface and groundwater supplies. Australian soils are highly dependent upon vegetation cover to generate nutrients and for stability. Land clearing, water extraction and poor soil conservation are all causes of a decline in the quality of Australia's soils.
Australia is the driest inhabited continent on earth, with the least amount of water in rivers, the lowest run-off and the smallest area of permanent wetlands of all the continents.
One third of the continent produces almost no run-off at all and Australia's rainfall and stream-flow are the most variable in the world.
Human activity continues to exert pressure on marine environments. Pollution is the most serious problem and the vast majority of marine pollution is caused by land based activities — soil erosion, fertiliser use, intensive animal production, sewage and other urban industrial discharges.
Australia currently has 65 Ramsar (an international convention that provides the framework for conservation of wetlands) listed wetlands covering 7.5 million hectares and more than 850 of national importance. Australia's marine environment is home to 4000 fish species, 500 coral species in the northern reefs alone, 50 types of marine mammal and a wide range of seabirds. It is estimated that as many as 80 per cent of marine species found in southern Australian waters occur nowhere else
Australia is one of the most biologically diverse countries on the planet. It is home to more than one million species of plants and animals, many of which are found nowhere else in the world, and less than half have been described scientifically.
About 85 per cent of flowering plants, 84 per cent of mammals, more than 45 per cent of birds, and 89 per cent of inshore, freshwater fish are unique to Australia.
Australia is richly endowed with marsupials — there are more than 140 species.
At least 18 exotic mammals have established feral populations in Australia, with cats and foxes responsible for the decline and extinction of several native animals.
At least 2700 non-native (introduced) plants have established populations in Australia. Sixty-eight per cent of these introduced plants are considered a problem for natural ecosystems.
Flora and fauna
The high diversity of flora includes large numbers of species in ecologically significant genera such as Acacia, Eucalyptus, Melaleuca, Grevillea and Allocasuarina. Acacias tend to dominate in drier inland parts of Australia, while eucalypts dominate in wetter parts.
The most common vegetation types today are those that have adapted to arid conditions, where the land has not been cleared for agriculture. The dominant type of vegetation in Australia — 23 per cent — is the hummock grasslands in Western Australia, South Australia and the Northern Territory. In the east eucalypt woodlands are prevalent, and in the west there are Acacia forests, woodlands and shrublands. Tussock grasslands are found largely in Queensland.
In Australia there are more than 378 species of mammals, 828 species of birds, 300 species of lizards, 140 species of snakes and two species of crocodiles. Of the mammals, almost half are marsupials. The rest are either placental mammals or monotremes.
Among Australia's best-known animals are the kangaroo, koala, echidna, dingo, platypus, wallaby and wombat.