Earth and Environmental Science
Home > Earth and Environmental Science > Options > Introduced Species and the Australian Environment > Introduced Species and the Australian Environment: 2. Introduced species may impact on the environment
9.5 Option – Introduced Species and the Australian Environment: 2. Introduced species may impact on the environment
| Syllabus
reference (October 2002 version) |
||
|---|---|---|
2.
An analysis of introduced species indicates they may impact on either
the biological and/or the abiotic aspects of the environments |
Students learn to: | Students: |
Extract from Earth and Environmental Science Stage
6 Syllabus (Amended October 2002), © Board of Studies, NSW.
[Edit:6Aug 08]
Prior Learning: Science Stages 4–5
syllabus: Outcomes 5.10 (content 5.10 a and c).
Preliminary Course 8.3 (subsections 4,5,6).
8.4 (subsections 1 and 2).
Background: In the past people were not as aware of the importance of keeping non-native species out of Australia. For example studies weren’t done on the effect of cane toads on native and domestic animals, before they were introduced to control the cane beetle.
describe the biotic and abiotic components of a local environment
- Revise the work you did in the Preliminary Course, 8.3 The Local environment
- The biotic aspects of the environment consist of all
the living things that make up the environment. These include:
- food – including plants and animals eaten by the animals in the particular environment
- predators
- other species that organisms depend on such as symbiotic relationships
- parasites
- competing organisms
- plants that provide homes for animals
- Abiotic aspects consist of non-living features of the environment. These include:
- sunlight readily available at the earth’s surface
- air including oxygen needed by all organisms
- heat to sustain chemical reactions of life
- fresh water for the survival of plants and animals. Water is the solvent in which chemical reactions occur at the cellular level of all living organisms. Some organisms live in saltwater environments.
- minerals, including trace elements
- acidity which may enable a soil to free up nutrients or lock them in compounds
- salinity - when water contains salts it is crucial that the concentration of these salts does not affect the free flow of pure water across biological membranes (osmosis).
perform a first-hand investigation by visiting a local environment, to identify and distinguish between biological and physical aspects of the environment that have been affected by introduced species
- To perform this investigation you should take a field trip to an area that has been affected by introduced species.
- Name the introduced species.
- try to identify the aspects of the environment that have been affected by the introduced species. Then distinguish between those aspects that are biotic and those that are abiotic.
- A simple three column table could assist recording results.
| Species Name | Aspect | Description | Classification |
|---|---|---|---|
| rabbit | plant cover | Rabbits have eaten all the plants on one side of the fence right down to ground level, leaving no food for domestic or native animals | biotic |
| rabbit | soil | The soil has eroded due to the lack of plants leaving the soil bare, with no roots to hold it together. | abiotic |
Click here 
to see rabbits drinking from a water hole when they were in
plague proportions in the 1930's. ABC Science, Australia
explain how some introduced species alter the abiotic characteristics of the Australian environments they colonise and why such environments are vulnerable to change
- The Australian climate can vary from periods of excessive rain at one time to months of dry and from one region of flooding to bushfire and drought declarations in another.
- Introduced species place an extra pressure on the limited resources available to the environment. For example, the large reproductive capacity of rabbits contributes to the decline of many native animal and plant species. Because the rabbits eat seedlings, many communities of plants may not be able to mature and produce seeds for the next generation.
- When soils lose their plant cover, they become susceptible to erosion, resulting in the topsoil being lost. It is then difficult for new plants to grow in the remaining subsoils.
- Introduced animals with cloven hoofs like cattle, sheep and goats compact the soil when they walk on it constantly compared to soft padded feet that kangaroos, wallabies and all the small marsupial mammals have. These marsupials do not harm the delicate soils.
- Further erosion may cause the saline zone of some soils to be exposed hence causing a saline scald. It then becomes impossible for natural regeneration.
- Many of these processes contribute to desertification (the making of deserts).
|