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3.1.1 An overview of the Australian Environment before human settlement.
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Continental Drift Theory
Watch the following clips to reinforce your understanding. The first provides explanations of the evidence to back up the continental drift theory. The second clips demonstrates the movement of the earths continents over the last 600 million years.
Continental Drift Theory - Youtube Clip
Earths History in the last 600 million years - Youtube Clip
Fire and Flora in Australia
Fire has played a most significant role in shaping Australia since the break up of Gondwana. Australian plants are heavily adapted to survive and even thrive (in some cases) from large scale fires. We also know that the indigenous Australians used fire to promote regrowth of vegetation.
DPI's history on major fire events in Australian history
Facts on Eucalypts in Australia
Biological Isolation
As Australia is separated from other continents, over the past 40 million years the flora and fauna has evolved in isolation, spared from interacting with other species, resulting in a unique and diverse range of plants and animals.
- Australia has 12 of the 19 known families of primitive flowering plants, two are not found anywhere else
- 95% Fungi, 85% Land Marsupials, 89% Land Reptiles, 94% Frogs, 57% Mangroves - none of these are found anywhere else in the world.
Geological Stability
As you can see on the right (picture), Australia is not situated on any tectonic plate boundaries. This means that Volcanoes and Earthquake's do not occur, resulting in a geologically stable continent. Unfortunately, these are responsible for recycling rock and soil, therefore the soil in Australia is poor in nutrients due to weathering processes (e.g. erosion). Poor soils have resulted in high levels of biodiversity, as dominant species are unable to exist. Flora is forced to co-exist, allowing for a great diversity.
Climatic Variations
Australia is, generally speaking, the driest inhabited continent. Large deserts and arid lands continue to play a role in the development of flora and fauna.
The change in ocean temperatures of South America have led to long periods of drought, and also long periods of flooding, further influencing flora and fauna. These periods of weather can range from 1-10 years.
El Nino - Drier than normal conditions across northern and eastern Australia, increasing drought and the risk of bush fires, causing haze and poor air quality. (See left map of dry winter/spring during El Nino). Drought leads to plants using strategies to conserve or reduce the need for water. Bushfire leads to adaptation from flora and fauna.
La Nina - The reverse of El Nino, resulting in higher periods of rainfall, this can lead to flooding. (See right map of wet winter/spring during La Nina, compare this to El Nino). Flooding leads to large-scale bird migration patterns, who are after wetland habitation.
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BIGSCV Examples
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Questions to complete