Australia Yearbook - 2009-10

Diversity of Australian
landscapes – from the Alps to
the Desert
The Australian Alps are located in the
south-east of Australia, forming part of the
Great Dividing Range. The Alps contain the
highest peaks in Australia, with the
Kosciuszko Plateau including the most
striking examples of glacier-formed
landscapes on the continent. Distinctive
features of the Australian Alps include high
altitude peaks and plateaus, glacial lakes and
alpine and sub-alpine ecosystems. Many
distinctive species have adapted to the cold
climate of the Alps, including snow gums,
unique wildflower species, mountain pygmy
possums and migratory Bogong moths.
The Simpson Strzelecki Dunefields extend
from the southeast of the Northern
Territory, through the northeast of South
Australia and into Queensland and New
South Wales. In contrast to the Australian
Alps, the landscape of the Simpson
Strzelecki Dunefields is characterised by
long parallel sand dunes, fringing dunefields,
extensive sand plains, dry watercourses and
saltpans. The predominant vegetation is
Spinifex hummock grasslands, sparse acacia
shrublands and some river red gum and
coolibah river woodlands.
A very different range of distinctive species
have adapted to this environment to that of
the Australian Alps. Species such as Acacia
nelsonii, the Eyrean grasswren and the Lake
Eyre dragon are endemic species which have
adapted to the unique desert landscapes of
the area.
Because of Australia’s geographic isolation,
many of its aquatic species are endemic and
include species that have existed continuously
in Australia for millions of years (such as
syncarid shrimps, petalurid dragonflies,
lungfish and salamander fish). Studies of
Australia’s freshwater biodiversity have
identified the likelihood of high levels of local
endemicity, groups of species and subspecies
that are difficult to separate on physical
characteristics (e.g. shrimps), and some species
with limited distribution (mountain stream
frogs, crayfish, and some species of mayflies,
stoneflies, caddisflies, dragonflies and
damselflies). This means that there are likely to
be many more aquatic species in Australia than
are currently described.
Marine and coastal ecosystems
Australia’s marine and coastal environment is
one of the most expansive and diverse in the
world. The oceans of Australia cover 16 million
square kilometres, and Australia’s 37,000
kilometre coastline is one of the world’s
longest. Australia’s Exclusive Economic Zone is
divided into 41 provincial bioregions; the
continental shelf is further divided into 60
meso-scale bioeregions. 6 Marine habitats
within Australia’s oceans range from tropical
marine to sub-Antarctic ecosystems. They
include extensive coral reefs (both the largest
coral reef province – the Great Barrier Reef –
and the only extensive fringing reef on the west
coast of a continent in the world – Ningaloo
Reef), the largest areas of seagrass plains in the
world, giant kelp forests, sand-bottomed
habitats that cover much of the continental
shelf, seamounts, and extensive mangrove
forests (with more than 50 per cent of the
world’s mangrove species).
Australia’s diverse marine ecosystems are home
to 11 per cent of the world’s known marine
species. They support over 5000 species of fish
– one of the world’s most diverse fish faunas –
and about 30 per cent of the world’s sharks and
rays. The southern Australian coastline alone is
home to one of the most diverse collections of
crustaceans, sea squirts, sea mats and sea
mosses in the world as well as the highest
known diversity of red and brown algae – more
than 1150 species.
Biodiversity decline in
Australia
Biodiversity decline is the loss of variety in
living systems. Decline can be measured
through a number of characteristics: it can be
decline in the number and range of species in a
particular region, the loss of genetic diversity
within populations of individual species, or
more broadly, the loss and simplification of
ecosystems.
6 Year Book Australia 2009–10