Australia’s Flora

1. Australia’s Flora Year 10 Banksia by Sydney Parkinson (1759-68). Image courtesy of National History Museum, London.

2. Australia’s Flora • Australia’s distinctive flora dates back to a time when the continent separated from the rest of Gondwanaland: about 30 to 40 million years ago. • Since then it has evolved in isolation. • As a result, 80% of all Australian plant species are endemic. Endemic: Flora and Fauna species that do not occur naturally anywhere else in the world.

3. Acacias Australia’s Dominant Vegetation Eucalypt Casuarinas Hummock Grasses Grass Trees Banksias

4. Eucalypts • One of the most dominant and abundant flora species in Australia is that of the Eucalypt. • Australia’s eucalypts are well adapted to the conditions in which they live. • Their small, hard, leathery and spiny leaves are an adaptation to low- nutrient soils and dry conditions. • Plants whose leaves are adapted in this way are referred to as sclerophylls

5. There are 4 main types of Eucalypt forests in Australia: • Wet sclerophyll forests- These generally occupy moist gullies and the southern aspect of hillsides in areas with relatively high rainfall. • Dry sclerophyll forests- This vegetation type has specifically evolved to suit the low-nutrient soils, to withstand drought and to regenerate after fire. This type of forest is a typical example of ‘the Australian Bush’ as most of us know it. • Eucalypt woodlands- Australia’s woodlands are a combination of Eucalypts and grasslands; the mix is determined by the local conditions of aspect, soil and topography. • Mallee woodlands- Mallees are stunted multi-stemmed eucalypts growing as small trees, which are adapted to drought and fire. Most Mallee country has now been cleared for agriculture.

6. Non- Eucalypt vegetation types • Acaciasare almost as widespread as eucalypts. They dominate in drier areas. • Mulgaoccupies about 20% of the continent. • Casuarinas have a pine like appearance growing often along riverbanks and creeks • Hummock grassesoccupy arid and semi arid areas.

8. Rainforests • Rainforests once covered the whole of the continent. • Today they cover just 0.25 %. • As the continent drifted to the north and the continent’s climate became drier, the rainforest vegetation retreated to the isolated pockets of land where rainfall was at least 600mls a year and the risk of fire was minimal.

9. Flowering Plants • Australia’s long period of isolation has also resulted in it having some of the worlds most exotic and spectacular flowers. • The international demand for these flowers has resulted in an export trade worth at least $40million a year.

10. The Australian Coat of Arms, showing the branches, leaves and flowersof the Golden Wattle.

11. Revision: Account (state reasons)for Australia being so dry. • A combination of factors contributes to the dryness of the Australian continent:

12. Answer • dominance of high pressure systems: with dry subsiding air diverging at the surface, producing fine, stable weather. • flatness of the Australian continent: absence of any substantial mountain range except for the Great Dividing Range which is poorly positioned close to the east coast preventing moisture penetrating inland. • Compact shape of the continent: no large bodies of water extending the maritime influence further inland. • Cold ocean currents off the west coast: cooling the air and reducing evaporation so little moisture moves onto the continent from the west. • (You may include influence of El Nino: a climatic variability associated with colder sea temperatures adjacent to northern Australia resulting in less moisture coming onto the continent)

13. Describe (provide characteristics and features)the features of the physical environment that create such a unique continent in Australia.

14. Answer • Features that may be included: • The world’s smallest continent and largest island. • Immense geologic age and stability have resulted in it retaining many of the oldest things on Earth eg. rocks and fossils, soils, plants and animals. • Lowest and flattest of the earth’s landmasses because of millions of years of denudation. • Isolation resulted in distinctive flora and fauna with 80% of species endemic to Australia. • The world’s hottest and driest( inhabited) continent. • The great age of Australia has resulted in large deposits of valuable minerals and energy resources.