Native and Invasive Plants

Eastern Suburbs Banksia Scrub (ESBS) – Native and Invasive Plants

The Eastern Suburbs Banksia Scrub (ESBS) is made up of more than 65 different native plant species, many of which form smaller subcommunities within the ecosystem.

Native plants are essential to this community — they provide food and shelter for native animals, and are well adapted to the local climate, sandy soils, and coastal conditions.

Native Plants of the Eastern Suburbs Banksia Scrub

Wallum Banksia (Banksia aemula)

[Image: Wallum Banksia tree Banksia aemula. Credit: John Spencer/DCCEEW 145463]

• One of six banksia species found in the ESBS
• Can grow up to 8 metres tall, or spread out as a low-growing shrub
• Thrives in nutrient-poor sandy soils
• Flowers produce nectar that attracts small marsupials, birds, and insects
• As a dense shrub, it provides excellent habitat for nesting birds 

Sydney Golden Wattle (Acacia longifolia) 

[Image: Sydney Golden Wattle Acacia longifolia. Credit: Stephen Alton/DCCEEW 117449]

• Grows as a large shrub or small tree, reaching up to 8 metres tall
• Highly drought-tolerant and its phyllodes (flattened leaf stems) help reduce water loss
• Has deep roots that stabilise sand dunes and prevent erosion
• Like other acacias, it can fix nitrogen — converting atmospheric nitrogen into a form that plants can use, improving soil fertility
• Its bright yellow flowers provide nectar for many small animals, including birds and insects 

Coastal Tea-tree (Leptospermum laevigatum)

[Image: Coastal Tea-tree Leptospermum laevigatum. Credit: Alan Fairley/DCCEEW 190950]

• Grows as a shrub or small tree, between 2 and 8 metres tall
• Common in sandy, humid areas with high rainfall
• Has long roots that help stabilise sandy soils and prevent erosion
• White flowers are an important nectar source for small marsupials, birds, and insects

Invasive Species — Weeds That Threaten the Eastern Suburbs Banksia Scrub

Over time, many non-native plant species have been introduced to the ESBS ecosystem. These invasive weeds compete with native plants for light, nutrients, and space, reducing biodiversity and changing the structure of the habitat.

Weeds tend to be fast-growing and reproduce rapidly, making them difficult to control. 

African Lovegrass (Eragrostis curvula)

[Image: African Lovegrass Eragrostis curvula. Wikimedia Commons]

• A grass species native to southern Africa, introduced to Australia (likely before 1900) as a contaminant in pasture seed
• Grows well in poor soils and is highly drought-tolerant
• Each seed head contains 300–1000 seeds, which spread easily by wind, water, and animals
• Once established, it can form dense clumps that crowd out native grasses 

Lantana (Lantana camara)

[Image: Lantana Lantana camara. Credit: John Spencer/DCCEEW 178980]

• A flowering shrub native to Central and South America
• Brought to Australia as an ornamental plant in 1841 and quickly became invasive
• Thrives in warm, high-rainfall environments and grows along forest edges or disturbed areas
• Forms dense, impenetrable thickets that smother native plants, preventing them from growing
• Its seeds spread easily by fruit-eating birds, and can remain viable for over four years 

Bitou Bush (Chrysanthemoides monilifera)

[Image: Bitou Bush Chrysanthemoides monilifera. Credit: Nick Cubbin/DCCEEW 132854]

• A flowering shrub native to South Africa
• Extremely hardy, tolerating full sun, shade, salty winds, and drought
• Originally introduced to stabilise sand dunes after mining, but quickly spread beyond control
• Seeds are spread by birds and mammals that eat the fruit
• Stem fragments can also grow into new plants if buried in sand or soil
• Forms dense thickets that displace native vegetation and change the natural dune ecosystem

Native plants like banksias, wattles, and tea-trees are vital to the health of the ESBS ecosystem — they support wildlife, prevent erosion, and maintain soil fertility.

However, invasive weeds like African lovegrass, lantana, and bitou bush threaten this balance by outcompeting native species and reducing biodiversity. 
 

Protecting and restoring the ESBS requires active weed management and native plant conservation.

Methods for Surveying an Ecosystem  

There are many different methods that can be used to study and record living things in an environment. Each technique helps scientists collect data about species diversity, abundance, and change over time.  

Quadrat Sampling  

A quadrant is a small, square frame used to study a defined area within an ecosystem. Quadrats can vary in size depending on the investigation, but a 1 x 1 m frame is a good place to start. Once a quadrat is placed on the ground, all of the observed species within the quadrat are counted and recorded. To make the data more reliable, counts can be made from several different quadrats and then averaged, since ecosystems are rarely uniform.  

Transect Survey  

A transect involves stretching a line or tape measure across part of the study area and recording the living things that occur along it. This helps show how species and vegetation types change across a distance, such as from shady to sunny areas or from dry to damp soil.  

Observations  

Observation is one of the simplest and most powerful methods. An area is watched carefully and notes made about the observed species, the number of individuals of each species, and how the different species interact with one another and their surroundings.

Sketches  

Drawings can show where plants and animals are located and how the landscape looks at a particular point in time. Creating several sketches over weeks or months can reveal how an ecosystem changes.  

Secondary Source Investigation  

Online databases and existing research can support an investigation. Tools like the Atlas of Living Australia can provide species records, maps, and biodiversity data to compare with the findings of a new investigation.