Chapter 6 Flashcards
What is Pangaea
The supercontinent consisting of all the earth’s land masses. Split into two large land masses called Laurasia (north) and Gondwana (south)
Why was Pangaea important to Australia
Important stage in the physical isolation that was to give Australia’s biota such distinctive characteristics
What was Laurasia
The northern supercontinent formed after Pangaea broke up. Included North America, Europe, Asia, Greenland and Iceland
What is Gondwana
The southern super continent that drifted apart to form Antartica, India, Africa, Australia and South America
What is continental drift
The theory describing movement of continents resulting from movement of plates in the Earth’s crust
How are ice cores used as an evidence of change
Drilling down into ice at the poles and within large glaciers produces cores that have preserved a continuous record of past climactic conditions. Trapped gas bubbles and the presence or absence of traces of organisms reveal information about changes in temperature and concentrations of atmospheric gases
Define succession
The progressive change of communities over time
Define nudation and give examples of what causes it
The development of bare sites with no organisms inhabiting the affected area. Caused by volcanic eruptions, cyclones, earthquakes and tsunamis
What is a pioneer plant
A plant capable of invading bare sites, such as newly exposed soil surface
What is primary succession
The colonisation of plants in a barren place
What is an example of primary succession
Autotrophic organisms (lichens) are first to become established in harsh surroundings. Acids secreted by the lichens attack the rocky surface allowing dust particles to settle in cracks. Shallow soil makes it possible for mosses to grow. When they die they add nutrients.
What is secondary succession
through natural disaster and human impact, dramatic changes to organisms occur. The cycling of matter and flow of energy are interrupted as the components of the ecosystem are affected
What is a climax community
The end point in a community succession where the community has become relatively stable (eg old growth forests)
What is an example of Australian climax communities
The old growth forests of Cooloola National Park in south east Queensland and the temperate rainforest pockets scattered throughout the east coast of Australia
Effect of fire on ecosystems
Loss of vegetation, reduction of leaf litter and a decrease in animal numbers
What is an urban ecosystem
An ecosystem with reduced biodiversity and us dominated by people. There is little recycling of matter and an increase in output of wastes into the atmosphere, land and water
how much Habitat destruction has occurred in aus
Since 1750, more than 20% of Australia’s forests have been cleared for crops and grazing with nearly 90% of the vegetation cleared in fertile lands
What causes land and soil degradation
Hard hooved animals compact the soil when they craze. Those creates opportunities for invasive, shallow rooted, introduced plants at the expense of the deep rooted native plants
Define monoculture practices
When only one species of an organism is grown and biodiversity is reduced. Often requires extensive use of fertilizers and pesticides. Easy for pests to spread as natural enemies are no longer present
Name the 5 ways the distribution of water for human use has changed ecosystems
- Irrigation (places demands on supplies of water)
- Engineering (construction of dams deprive vegetation of flooding essential for survival and fish can become stranded)
- Degradation of urban streams and waterways (Drains deliver stormwater into streams causing physical and chemical disturbance to marine ecosystems)
- Desnagging (removal of logs from waterways for boats which reduces breeding sites for fish and increases erosion rates)
- Drainage of wetlands (important for processing large quantities of pollutants that would normally pass downstream)
How can introduced species become pests?
Without natural predators many introduced species become pests that affect habitats, food chains and the ecosystem. Examples include deer, camels, pigs cats and dogs
Explain how commercial fishing is causing marine organisms to be at risk of extinction
- Hunting: sharks hunted for leather, fish meal and fertilizer
- Over fishing: penguins and seals compete with the fishing industry for food
- Pollution: abandoned fishing lines and plastic kill turtles, seals and birds
- By catch: As populations of fish decrease, there are fewer fish reaching reproductive age to sustain population growth
- Pollutants such as oil can disrupt marine ecosystems
what is DDT
DDT was a commonly used pesticide as it was cheap and effective. IT affects the nervous system by interfering with normal nerve impulses DDT was a commonly used pesticide as it was cheap and effective. IT affects the nervous system by interfering with normal nerve impulses
What are the effects of DDT
In humans can cause nausea, diarrhea, tremors
In animals can cause chronic effects on the nervous system. DDT is insoluble in water and is highly toxic to aquatic organisms
Why was DDT used
- initially used by military in ww2 to control malaria, typhus, body lice and bubonic plague
- Farmers used DDT on crops as a pesticide
- Used in buildings for pest control
