Eucalypt forests

Understanding our world

Earth's natural systems are a framework for understanding our world. The systems include the atmospheric system, the hydrological system, the geomorphic system and the ecological system.

Using the systems approach we can analyse geographical observations by identifying the system, the circulations and cycles and recognising the processes that occur within and between systems. 

For example, to understand how plants produce biomass we consider their role as primary producers. Just like a factory they have different inputs and outputs. One input is carbon dioxide, a component of the atmospheric system. Through the process of photosynthesis, plants use carbon dioxide and produce oxygen. This is a key element of the oxygen cycle. Through this same process plants convert carbon dioxide into organic carbon resulting in plant growth and is measured as biomass. This is one element of the carbon cycle. By examining each system in turn students will develop and appreciate how natural processes shape the environment, influence climate patterns, impact ecosystems and ultimately affect human societies.

Learning through fieldwork 

Fieldwork enables students to make observations on geographical phenomena. Asking why, sparks a curiosity and a fascination as to why things are the way they are. In the Eucalypt forests of Sydney questions may include:

• Why do some plants have thick bark and others have none?

• Why are Australian soils low in nutrients?

• Do eucalypt trees encourage fire?

• Can eucalypt trees survive in prolonged drought?

• Would plants increase biomass if there were higher levels of carbon dioxide in the atmosphere?

These questions can be examined by analysing the processes, cycles and circulations of Earth's natural systems.

Eucalypt forests of Australia

Australia was once part of Gondwana. This supercontinent was covered in ancient rainforests. Approximately 40 million years Australia broke away and drifted north. The climate became warmer, drier, the soils less fertile and as a result fire prone eucalypts evolved. Eucalypt forests are now the most common forest type in Australia covering 77% of Australia's total native forest area. 

Today rainforests cover only 0.25% of the continent, 17% of which occurs in NSW and includes The Gondwana Rainforests of Australia World Heritage listed area in southeast Queensland and northeast New South Wales.

The change from rainforest to eucalypt forest is called ecological succession. It is a result of long term changes that occurred as a result of continental drift and climate change and consequent adaptation of plant and animal species.  

Classifying eucalypt forests

Eucalypt forest types are classified by vegetation structure and composition. Structure refers to the crown cover (tree foliage as viewed from above), plant height and the forest layers that includes the canopy and understorey layers. Composition refers to the plant species found within a vegetation community. 

In Australia Eucalypt forests are divided into three classes based on:

• crown cover - woodland forest (20 to 50% crown cover), open forest (>50 to 80% crown cover) and closed forest (>80 to 100% crown cover) - Source 1 - Australian Bureau of Agricultural and Resource Economics and Sciences.

• mature tree height - low (2 to 10 metres), medium (>10 to 30 metres), tall (>30 metres) - Source 2 - Australian Bureau of Agricultural and Resource Economics and Sciences.

In eucalypt forests, eucalypt trees dominate the canopy with an understorey of shrubs and grasses. 

The vegetation is described as sclerophyll. The term comes from the Greek 'sclero' meaning hard and 'phyllon' leaf. Plants are evergreen with leaves that are generally tough, thick, leathery and fall parallel or oblique to direct sunlight in order to reduce water loss. 

Forests at the Field of Mars Reserve

The eucalypt forest in the Field of Mars Reserve is classified as open forest with medium trees (>10 to 30 metres). This forest type has an open canopy allowing light to infiltrate to the forest floor. It receives an average annual rainfall exceeding 600 millimetres and has low soil fertility.

Learn more about eucalypt forests using the Field of Mars Environmental Education Centre Fact sheet and government fact sheets located in the Resources section of this website.

Forest plants

Activity 1

View the carousel of images to learn more about the plants that inhabit the forest at the Field of Mars Reserve. 

Select two plants for further investigation.

1. Conduct a photo sketch of your two selected plants. Identify the species and it's position in the forest as either canopy or understorey species.  Label and colour your sketch.

2. Conduct internet research on traditional uses of these plants.  

3. Conduct internet research on how the plant's features have enabled it to survive in its environment. 

4. Compare and/ or contrast the adaptations of your two plants.

Energy flows

A food chain is a linear representation of the flow of energy and nutrients through an ecosystem. It illustrates the feeding relationships between different organisms, showing how energy is transferred from one organism to another. The food chain typically starts with primary producers, such as plants then progresses through various levels of consumers, including herbivores and carnivores.

Each step in the food chain represents a trophic level, and the transfer of energy from one trophic level to the next demonstrates the interconnectedness of different organisms and highlights the dependence of each level on the one below it. 

Cycles

• carbon cycle

• nutrient cycle

• oxygen cycle

• water cycle

• rock cycle

Processes

• absorption

• biomass

• decompostion

• energy flow

• gas exchange

• photosynthesis

• productivity

• soil stabilisation

• transpiration