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Biodiversity is generally defined as the variety of life forms in a particular area, including the different plants, animals, micro-organisms, and the ecosystems they are a part of.
The ecosystems in our city include an array of environments, from suburban gardens to natural shrubland, dunes, and, of course, the sea.
Vegetation
The trees and plants around our city are quite different from those before European settlement. The dunes would have been much larger, both taller and spread more inland; the estuaries played host to bull rushes, reeds, and swamp paperbarks; and in the woodlands, various eucalypti, tea-trees, acacias, and sheoaks with a diverse understorey. Today, many of our public gardens and parklands include introduced species. However, we remain committed to improving biodiversity in the natural and built environments, which will benefit the community and future generations.
Managing our biodiversity includes targeting and eradicating high-priority weeds, reintroducing rare and threatened species, and managing threats to these ecosystems. We encourage our community to connect with nature for multiple benefits, so we provide amenities such as benches and pathways.
More Information
If you are planting a water-wise, wildlife-friendly garden and looking to use local native plants, please see our green living page. If you'd like to plant up your verge with native plants, we provide a suitable list of species on our verge page, along with our verge management policy and Verge application form, which you must submit before planting.
Weeds
Weeds are defined as “plants growing where they are unwanted.” When it comes to natural areas in the City of Holdfast Bay, the plants that we define as weeds are non-indigenous. Native fauna, including bees, butterflies, and birds, rely on Indigenous plants for food and habitat, which is why keeping weeds at bay and planting Indigenous species is so important.
Weeds in South Australia are classified by the level of threat they pose to agriculture, environment, and/or public safety. This classification hierarchy helps us to decide which weeds to remove first.
The most serious weeds are “declared” and regulated through the Landscape South Australia Act 2019. Declared weeds can severely impact our natural areas, where they can outcompete Indigenous plants and completely alter ecosystems, with profound consequences for native fauna. Habitat loss and alteration are the biggest threats to native fauna locally and globally.
Here are some of the main declared weeds in the council area that you should look out for and remove, with suggested indigenous species to replace them.
| Declared Weed | Suggested Indigenous Replacement |
|---|---|
| Gazania spp. (gazania) | Lotus australis (austral trefoil) |
| Cenchrus setaceus (fountain grass) | Poa poiformis (coast tussock grass) |
| Uncultivated Olea europaea (olive) | Banksia marginata (silver banksia) |
| Coprosma repens (mirror bush) | Myoporum insulare (common boobialla) |
| Rhamnus alaternus (buckthorn) | Scaevola crassifolia (cushion fanflower) |
| Tribulus terrestris (caltrop) | Kennedia prostrata (running postman) |
| Lycium ferocissimum (African boxthorn) | Dodonaea viscosa ssp. spatulata (sticky hop bush) |
| Chrysanthemoides monilifera (boneseed) | Olearia axillaris (coast daisy bush) |
If you want to report an infestation on public land or would like some assistance identifying a plant that you think should be declared, please email the council using the customer request form with clear photos of the whole plant and clear close-up photos of the leaves, flowers, and seedheads to assist with identification.
To find out more about declared weeds, some great sources of information are the Green Adelaide Landscape Board and Primary Industries & Regions SA (PIRSA)
Declared Weed FAQs
If you want to report an infestation on public land or would like some assistance identifying a plant that you think may be declared, please complete a customer request form with clear photos of the whole plant and clear close-up photos of the leaves, flowers and seedheads to assist with identification.
You can find this information on the Department of Primary Industries and Regions SA (PIRSA) website here. PIRSA and Green Adelaide are the main government departments that review and enforce declarations. Councils across South Australia work with them to help identify and report declared weed infestations and assist to educate the community about declared weeds.
Any weed can be disposed of in your green lid FOGO bin. The heat composting process used by commercial composters kills all plant propagules as per the Australian Standards for composts, soil conditioners and mulches, AS4454-2003. Declared weeds should not be disposed of in your backyard compost.
We are working towards controlling declared weeds on public land. Unfortunately, we can’t remove them all at once, so we prioritise those in and around our natural and revegetation sites, e.g. the dunes, Gilbertson, Barton, and Pine Gullies, and Kingston Cliff Face. We can’t do this alone; it needs everyone's cooperation. So, we need help from all landowners and residents, especially because 64% of the land in Holdfast Bay is private property.
Yes. We offer a 50% Green Living rebate on the purchase of indigenous plants from an indigenous plant supplier up to $40. Please see our Green Living Rebates page for more information on how to apply. Click here to view a list of indigenous plant suppliers.
We also hold a Gazania Free Gardens Indigenous Plant Swap and an Indigenous Plant Giveaway between May and July annually. For notifications, follow our Facebook or Instagram pages or subscribe to our fortnightly newsletter.
Natural Reserves
Four designated natural areas exist in our city, each with its own history and ecology. However, they share the common purpose of preserving the natural environment as much as possible.
- Barton Gully is at our most southern boundary. The upper section opens into grasslands, while the lower section becomes steep and narrow. It has a small, unique remnant section.
- Gilbertson Gully is our largest natural open space (>3 Ha), also near our southern border. It follows an ancient seasonal watercourse through a residential area and has at least one small, unique remnant section.
- Kingston Cliff Face marks the point where the foothills meet the sea. It is our highest biodiversity site, with more than 90 native plant species, and is significant as the only coastal cliff remnant within 15 km of the CBD. At the southern base of the cliff face is the Tjilbruke Spring, a 25-square-metre shallow marsh fed by underground seepage that discharges there and drains into the sea and is an important site for the Kaurna Nation.
- Pine Gully adjoins Kingston Cliff Face and forms part of a steeply sloped gorge. It has been highly modified and is dominated by Aleppo pines. It recently underwent a major upgrade to control stormwater, increase public access, and improve biodiversity.