Australia Yearbook - 2009-10

3. BIOREGIONS OF AUSTRALIA, Interim Biogeographic Regionalisation for Australia (IBRA) and
Interim Marine and Coastal Regionalisation for Australia (IMCRA)
Interim Biogeographic Regionalisation for Australia (IBRA)
Interim Marine and Coastal Regionalisation for Australia (IMCRA)
Source: Australian Government Department of the Environment, Water, Heritage and the Arts.
The list of nationally threatened species
continues to grow in Australia, with 426 animal
species (including presumed extinctions) and
1,339 plant species listed as threatened under
the EPBC Act. 9 Furthermore, there is some
evidence that the rates of recovery once a
species has been listed as threatened, whilst it
is difficult to determine in short time periods,
may be particularly low. In a study conducted
on 38 threatened species recovery plans across
every state and territory, evidence of ongoing
decline in populations was displayed in 37 per
cent of cases.
Species and ecosystems have complex and
important interrelationships. Some species play
important roles in the maintenance of
ecosystems, and the extinction of individual
species can have flow-on effects and impact
significantly on the function of the broader
ecosystem. The Cassowary, for example, plays
an important role in the dispersal of rainforest
seeds, with the rate of germination of many
plant species significantly higher after
Cassowary digestion of the seeds. Equally so,
many ecosystems play significant roles in
nurturing a variety of other species. Coral reefs
and mangrove forests are both very important
ecosystems in nurturing a great number of
marine species. The decline of these
ecosystems can affect hundreds of species that
depend on them.
The importance of species in
maintaining ecosystems
Species such as the bilby and the burrowing
bettong (boodie) move huge amounts of soil in
digging burrows and in foraging. These
activities, along with their selective browsing
on native shrubs, help shape the entire
ecosystem through seed entrapment, plant
germination and establishment, soil nutrient
stores and fluxes, water infiltration and storage,
soil respiration, microbial activity and litter
decomposition. Unfortunately these species are
now missing from most of their previous range.
The ecosystems which depended on the role
these species played are now also in decline. 10
8 Year Book Australia 2009–10