Biodiversity in Adelaide

Did you know that over 70 species of native bee live in the Adelaide Park Lands?

Australian native bees rely heavily on Australian native plants. The abundance of flowering native plants in the Adelaide Park Lands, which provide nectar and pollen, attract an abundance of native bees. But not just any plant species will do – many bee species need particular plant species to feed on, and the lack of flowers from suitable plants is the largest threat to Australian native bees.

However, suitable habitat is also important. About 70% of native species dig nests in the ground, but the remaining 30% use hollows in stems and wood or dig nests in soft stems. Carefully designed ‘bee hotels’ provide the necessary habitat for these species and are helping to support native bee diversity in the Adelaide Park Lands.

Three such bee hotels are located around the Park Lands, and recent surveys have shown that locally native bee species have moved in. Hotels installed by the City of Adelaide in Bonython Park / Tulya Wardli (Park 27), G S Kingston Park / Wirrarninthi (Park 23), and Mistletoe Park / Tainmuntilla (Park 11) were found to be supporting seven different species of native bee.

These hotels are great for providing nesting sites for some of our native bee species, but they’re also a great opportunity for human visitors to get up close and observe our native bees which are non-aggressive and are unlikely to sting unless heavily provoked!

Downstream of the Torrens Weir, Karrawirra Pari (Red Gum Forest River) runs through Bonython Park / Tulya Wardli (Park 27). This section of river is a natural oasis thanks to a concerted revegetation effort to transform the area into a riverbank (riparian) ecosystem that more closely resembles its natural condition.

Years of colonial mismanagement had left the area in a degraded state with a high abundance of invasive weed species. Early stages of the restoration project removed large woody weeds such as willow and ash trees, as well as smaller herbaceous weeds. This was followed by the planting of 100,000 locally native plants which have since established well and are providing habitat for a range of animal species.

This stretch of Karrawirra Pari is now in much better condition and is a more pleasant space to visit and explore. Ongoing effort is being made to restore the riparian environment to a healthy Karra / River Red Gum (Eucalyptus camaldulensis) Woodland.

Pest species are any plants or animals that cause detrimental effects to an ecosystem. One such species that has caused significant damage to Australia’s waterways is the European Carp (Cyprinus carpio). Since 2011, the City of Adelaide has engaged South Australian Research and Development Institute (SARDI) to reduce the population of carp in the Torrens Lake to improve water quality and the health of aquatic vegetation.

Over this time, 3563 individual carp have been removed from the system. Using electrofishing, whereby fish are temporarily stunned and selectively removed, the density of carp in the Torrens Lake has reduced from 390 kilograms of carp per hectare in 2016 to 65 kg/ha in 2023. This is an 83% reduction in carp density and will have significantly beneficial effects on water clarity and aquatic vegetation which will benefit other native species and overall ecosystem health.

Weedy plants are managed daily using targeted herbicide and physical removal. Invasive plants can outcompete native species and reduce the quality of native habitat – they are managed to improve habitat condition and promote enhanced native biodiversity.

Trees are an important part of ecosystems. Their canopies cool the air by providing shade and releasing water from their leaves, and they improve air quality by filtering out pollutants. They also provide resources for many animal species such as food via their fruits and flowers, and habitat via their branches and hollows.

However, trees alone are not enough. Healthy ecosystems have multiple layers of vegetation that provide structural diversity – a variety of habitat types that cater to the different needs of different animal species. Shrubs, grasses, and groundcover plants are highly important in providing a diversity of habitats and therefore supporting a diversity of animals that fulfil different roles in a system. This is why the City of Adelaide is focusing conservation and restoration efforts on protecting and enhancing understorey habitat, including by planting a variety of locally native shrubs, grasses, and groundcover plants. By planting these understorey species, the City of Adelaide is helping to provide structural diversity and habitat resources that will improve the health of the ecosystem.

You can do the same! Planting locally native understorey species at home will help provide important habitat for invertebrates, small birds, and lizards that are often missing from areas lacking understorey plants. Providing necessary habitat will improve local biodiversity by attracting more than just the generalist species (ahem, Noisy Miners).