A vital indicator of the health of Australia's biodiversity is the status of its ecosystems and species. The Audit's Terrestrial Biodiversity Assessment provides the first comprehensive compilation of Australia's threatened ecosystems.

Ecosystems

• Australia has 2891 threatened ecosystems. 39% of bioregions have more than 30% of their ecosystems threatened. The highest number of threatened ecosystems occurs in southern and eastern Australia (Map 1).
• Nearly half of the threatened ecosystems are forest and woodland with shrubby or grassy understorey.
• Vegetation clearing and increased fragmentation of vegetation remnants are the most significant threats in eastern Australia. Additional threatening processes are firewood collection in parts of southern Australia, salinity and other changed hydrology, and exotic weeds.

Map 1: The percentage of threatened ecosystems identified across bioregions. Threatened ecosystems include ecosystems and other ecological assemblages. In some bioregions, the total number of ecosystems has not yet been determined to enable a percentage to be derived.

Species

• Very high numbers of threatened species occur in the Murray-Darling Basin and the developed coastal parts of eastern Australia, southern Australia and in south-west Western Australia, with 236 threatened species occurring in the Murray Mallee subregion in Victoria (Map 2).
• The most common threatening processes are:
  • vegetation clearing, particularly in Queensland, New South Wales and Tasmania;
  • increased fragmentation of vegetation remnants in New South Wales and south-western Australia;
  • overgrazing and feral animals across much of central and western Australia;
  • inappropriate fire regimes in northern Australia;
  • changed hydrology from various causes; and
  • increasing salinity in many developed landscapes.

Map 2: Total number of threatened species by subregion.

Further Information:

• See Australian Terrestrial Biodiversity Assessment 2002 for more details.
• Or go to the Australian Natural Resources Atlas (www.environment.gov.au/atlas).
• Email: info@nlwra.gov.au