Themeda Grassland on Seacliffs and Coastal Headlands
What is Themeda Grassland?
Themeda Grasslands is a vegetative community that it typically a closed tussock grassland. However it can also be structured as a open shrubland or open heath with a grassy matrix between the shrubs.
Themeda Grasslands are dominated by Themeda australis - the Kangaroo Grass, which features amongst a range of other native grasses, groundcovers and coastal scrubs.
Coastal Headland Grassland forms a component of this Endangered Ecological Community.
Where is it found?
Themeda grasslands can be found on a small number of seacliffs and coastal headlands within the Pittwater Council area. They include Long Reef Point, Narrabeen Head, Turimetta Head and Mona Vale Headland Reserve. Smaller remnant areas can also occur on other headlands with sandstone derived soils, seacliffs and talus slopes. Overall, the community has a highly restricted geographic distribution comprising small, but widely scattered patches.
What does it look like?
Because of its variable structure, Themeda Grasslands can have a range of different appearances from grassland, to open shrub to open heath. The main species which dominate Themeda Grasslands is Kangaroo Grass. Kangaroo Grass is a distinctive tufted perennial which stands prostrate and can grow up to 1.5 metres high. It produces distinct large red-brown spikelets which are wedge shaped and surrounded by leaf-like spathes. The leaves are also distinctive in that they are glaucous or wax coated.
Amongst The Kangaroo Grass are a number of native grasses, groundcovers and scattered coastal shrubs (which are usually dwarfed in form). These shrubs include the Coastal Wattle a spreading, scrambling wattle that bears bright yellow cylindrical flower heads in the spring.
Along with the Coastal Wattle is the Coastal Tea Tree a twisted scrub that has distinctive greenish-grey leaves which are obovate is shape. Some stands include the Spiny Mat Rush a tussock grass that bears long dark green strap-like leaves arching from the centre.
Why is it threatened?
There are a number of factors which have significantly reduced the distribution of Themeda Grasslands within Pittwater and the surrounding regions. They include coastal development, invasive weed species, recreational use and erosion.
Invading weed species such Bitou Bush and Lantana and native species including Coastal Wattle, Coastal Banksia and Native Rosemary out-compete the native species occurring in Themeda grassland and can convert it to dense scrubland.
Recreational use has also had an impact with erosion occurring around footpaths and tracks made by off-road vehicles. Collectively, these processes can result in a large reduction of the ecological function of the Themeda Grassland community.
At Narrabeen Headland, a long history of disturbance which includes being used for gun emplacements and a car parking area and picnic ground during the 1960s, has enabled weeds to colonise the area.
What is special about it?
Themeda Grasslands are rare. There are only four remaining sites within Pittwater where Themeda Grasslands can be seen and these are small and widely-scattered patches. A number of threatened plant species also grow in Themeda grassland.
They can include Diuris sp. aff. chrysantha, Pultenaea maritima, Rutidosus heterogama, Thesium australe and Zieria prostrata. Themeda Grassland is also a major habitat for a number of other species, including Chamaecrista maritima, Plectranthus cremnus and Stackhousia spathulata.
What plants/animals are found in Themeda Grassland?
Themeda Grassland is dominated by Themeda australis (Kangaroo Grass), with other native grasses including Microleana stipoides (Weeping veldt Grass) and Dichelachne micrantha (Plume Grass).
Looking closely, you may see the native Thysanotus tuberosus (Fringed Lily), Pimelia linifolia (Slender Rice Flower), and Lasiopetalum ferrugineum (Rusty Petals).
- Plant species list for Themeda Grassland (PDF 25KB)
Themeda Grasslands are made up of a number of grasses and groundcovers which can be important habitat for native animals including insects. The Kangaroo Grass is thought to be a likely food source for the caterpillars of the moth species Pterolocera amplicornis.
Nectar producing species such as the Coastal Wattle provide an important food source to local and nomadic possums, squirrel gliders and birds such as honey eaters, wattlebirds and lorikeets.
Themeda Grasslands also provide important habitat for predatory birds, such as the Nankeen Kestrel (Falco cenchroides). These birds require open areas to hunt small invertebrates which dominate their diet. Species which are encroaching from the neighboring Open Scrub community may be changing the nature of the habitat for these predatory species.
What is Pittwater Council doing to protect it?
Council has contracted professional bush regenerators maintain and improve existing Themeda Grassland stands through weed suppression, planting and general maintenance.
The Council It is also supporting volunteer bushcare groups with the provision of tools, removal of weeds, on-site supervision by a trained bush regenerator and employment of a professional Bushcare Program Coordinator.
What you can do to healp protect Themeda Grassland
- Control weed invasion of Lantana and Bitou Bush on your property
- Minimise Human disturbance by staying on designated pathways such as those along the Bicenntenial Coastal Walkway
- Join your local Bushcare group and help conserve and protect the remaining Themeda Grasslands. If you want further information or to join please contact the Council's Bushcare Officer on 9970 1367.
Updated: 16 Nov 2012