Linking together to protect our bioregions – a closer look at the biodiversity of South Australia

Overview

1. Introduction

Many South Australians have a strong connection to the natural environment, enjoying the outdoor life of the beach, the hills and the bush. Learning about what makes our environment special helps us to both better understand it and appreciate its uniqueness. This resource provides detailed information on the three Biomes that occur across South Australia and thevariety of biodiversityfound in them. By understanding the importance of biodiversity we can make informed choices to better protect our biodiversity for future generations.

2. Bioregions

Bioregions are areas defined by features of the natural environment and provide a context for discussing biodiversity and its conservation. South Australia’s three biomes (collections of ecosystems), contain bioregions which form a mosaic of ecological communities containing a distinctive blend of species and habitats. Biodiversity includes all the living things within and across each bioregion.

3. Biodiversity

Biodiversity, or biological diversity, is the variety of all species on earth. It is the different plants, animals and micro-organisms, their genes, and the terrestrial, marine and freshwater ecosystems of which they are a part. Biodiversity is essential for the existence and wellbeingof all species.

4. Threats

Our bioregions and biodiversity face a variety of threatening processes, most of which are influenced by people. These include:loss, fragmentation and degradation of habitat; the spread of invasive species; unsustainable use of natural resources; climate change; inappropriate fire regimes; and changes to the aquatic environment and water flows. We need to minimise threats to South Australia’s biodiversity and protect it for the long term.

5. Conservation

South Australia has developed a world class reserve system to conserve the diverse habitats and ecosystems found in our state’sland and marine bioregions. There are many conservation programs actively conserving and improving our state’s biodiversity.

6. Resources

Detailed fact sheets about the bioregions help us to learn more about and appreciate each bioregion’s unique biodiversity in terms of not only flora and fauna but cultural and geological dimensions. The fact sheets encourage exploration and connection to South Australia’s unique bioregions and include ideas for restoring and enhancing South Australia’s biodiversity.

Connect withgroups and programs taking action for biodiversity in your bioregion!

1. Introduction

This resource provides detailed information about South Australia’s bioregions and unique biodiversity. By understanding the importance of biodiversity we can make informed choices to better protect our biodiversity and maintain it for future generations.

Australians have a strong connection to the natural environment, enjoying the outdoor life of the beach, the hills and the bush. All life on earth is directly dependent on the health of our natural environment. Environmental systems, when healthy, provide us with breathable air, drinkable water, fertile soil, food, resources and a sense of wellbeing. In recognising our place in the natural environment, we recognise that the variety of life also has value in and, of itself, beyond its usefulness to us.

‘Biodiversity’ is the variety of life on earth. It is fundamental to all life and is currently under threat across the world. As well as the numbers and diversity of species, biodiversity includes ecosystems and genetic diversity. Bioregions are broader than ecosystems and include the variety and arrangement of landforms, communities and land uses. In South Australia there are seventeen terrestrial (land) bioregions and eight marine bioregions which, combined, cover the whole state. These bioregions contain ecosystems with plant and animal species; some that can be found nowhere else on earth. As with many places in the world, these ecosystems are being degraded by a range of threats including climate change and habitat loss.

South Australia has many programs and projects that work to protect South Australia’s biodiversity across the bioregions by highlighting ecosystems, threatened species and nature conservation. The No Species Loss Strategy is a state biodiversity plan for halting the loss of native species. NatureLinks is developing new biodiversity corridor links to connect a range of habitats that have been fragmented, which will enable native wildlife to survive and adapt to environmental change. In addition to its numerous land-based National Parks and Conservation Parks, South Australia has also developed protected areas within its coastal waters and these marine parks will help safeguard and conserve the precious biodiversity that exists within the sea.

However to encourage the community to support these initiatives we need tolearn not only how to live more sustainably but to explore and develop our relationship with the natural world and our role as stewards from an early an age as possible. This resource is a valuable tool in that exploration.

2. Bioregions

Bioregions are areas defined by features of the natural environment and provide a context for discussing biodiversity and its conservation. South Australia’s three biomes contain bioregions which form a mosaic of ecological communities containing an integrated mix of species and habitats. Biodiversity includes all the living things within and across each bioregion.

A bioregion is an area of land or sea defined by common patterns of natural characteristics and environmental processes (such as geology, landform patterns, climate, ecological features and plant and animal communities). Each bioregion has a unique collection of ecosystems (self-organising and self-supporting collections of species living together) as well as different patterns of land use and threats to biodiversity.

Australia’s land is divided into 89 terrestrial bioregions, of which 17 are in South Australia. The bioregions are described in the interim Biogeographic Regionalisation for Australia (IBRA) ( The IBRA is the National Reserve System's planning framework, the fundamental tool for identifying priority targets across Australia. The Integrated Marine and Coastal Regionalisation of Australia (IMCRA) (l a spatial framework for classifying Australia's marine environment into bioregions based on their ecology and is used for regional planning. There are eight marine bioregions in South Australia.

2.1 Boundaries

A bioregion’s borders are defined by natural boundaries such as soils, mountains and rivers. These boundaries help define and break down large landscapes into smaller areas that are more easily understood and managed. Though bioregions have set areas based on natural boundaries; they do not come to an abrupt halt at their border. Instead, they blend into each other at the fringes - fringes which may be a few metres or many kilometres in breadth. While this resource focuses on South Australia, many of the bioregions cross over state or territory borders.

2.2 The Ecological Hierarchy
  • biosphere – the earth's ecosystem which includes all living organisms in the atmosphere (air), lithosphere (land) and hydrosphere (water).
  • biomes – collections of ecosystems with different patterns of climate, land use, vegetation and habitat.
  • bioregions – areas of land or sea defined by common patterns of natural characteristics and environmental processes
  • ecosystems – self-organising and self-supporting collections of species living together (CSIRO)
  • communities – populations of living organisms in an ecosystem interacting with each other
  • populations – the species of the same kind in a particular ecosystem
  • species – a group of organisms that share a set of common features.
  • genes – the genetic information contained in all individual living things, which varies within and between populations of organisms.
2.3 Ecosystems in South Australia

The ecosystems in South Australia are quite diverse. The bioregions are part of three biomes - the Arid Lands, Mediterranean and Marine biomes - which all support a range of plant and animal species. Each biome represents a simplified but unique collection of ecological communities with different patterns of climate, land use, vegetation, habitat and threats to biodiversity.

The biomes represent discrete spatial units but they are dynamic; they connect with each other, and species and ecological processes interact across them. It is critical to conserve connectivity, both within and between biomes, through appropriate landscape and seascape planning.

2.3.1 The Arid Lands Biome

In the north and west of the State is the Arid Lands Biome, which covers 87% of South Australia. There is significant variation in climate from the semi-arid south to the arid north. South Australia’s arid lands are characterised by episodic wet and dry cycles, where prolonged dry periods are often broken by high-intensity rains. These rains are highly unpredictable, infrequent and variable, and have shaped the natural processes. Animals and plants cope with prolonged dry periods and respond quickly to intense bursts of rainfall when the natural environment flourishes. Landforms represented in the Arid Lands include gibber and gypsum plains, dunefields and sand plains, and rugged, volcanic and quartzite mountain ranges. The biome also contains river systems with enormous variability in flow, arid watercourses, lakes, artesian springs, wetlands of international and national importance (including sites of national importance for migratory shorebirds), salt lakes, and major ephemeral watercourses which drain towards Lake Eyre. The high levels of intact vegetation include spinifex hummock and tussock grasslands, chenopod shrublands, open and low mallee, and eucalypt woodlands. The Great Artesian Basin underlies about 50% of this biome to the east. Four of Australia’s 12 plant ecosystems occur in the region, providing habitats for a significant proportion of South Australia’s reptiles (70%), birds, (57%), frogs (50%) and mammals (50%).

The Arid Lands biome includes the bioregions of:

  • Broken Hill Complex
  • Central Ranges
  • Channel Country
  • Eyre Yorke Block
  • Finke
  • Flinders Lofty Block
  • Gawler
  • Great Victoria Desert
  • Murray Darling Depression
  • Nullarbor
  • Simpson-Strzelecki Dunefields
  • Stony Plains.

Goyder's Line is a boundary across South Australia established in1865 which was believed to indicate where the level of rainfall would support agriculture. Above the boundary was considered too dry for cropping but suitable for grazing. The boundary follows clear changes in vegetation – mainly mallee scrub in the south and salt-bush in the north. With the increasing impacts of climate change this boundary is now considered to need moving about 100 kilometres south to around Clare.

2.3.2 The Mediterranean Biome
  • The southern part of South Australia contains the Mediterranean biome. The climate of the Mediterranean biome is cool to warm; tending to winter rains. The biome is characterised by undulating plains and foothills, low ranges, steep rocky gorges and creek lines. The highly fragmented vegetation includes chenopod shrublands, native grassland, sedgelands, samphireshrublands, native grassland, open mallee, eucalypt woodlands and sand dune fields. Its watercourses and rivers range from ephemeral to permanent and Kangaroo Island is uniquely fox and rabbit free. There is significant seabird nesting habitat on offshore islands. Although much smaller than the Arid Lands biome, the Mediterranean biome contains wetlands of international and national importance, which are also sites of national importance for migratory shorebirds (only 30% of pre-European wetlands remain).

The Adelaide and Mount Lofty Ranges region of the Mediterranean biome covers approximately 780,000 ha with around 97,000 ha of native vegetation remaining. It includes the Barossa and Mount Lofty Ranges, Fleurieu Peninsula, metropolitan Adelaide, 63 parks and reserves, and significant areas of native vegetation on private land, roadsides and council reserves. The region is effectively an island of habitat surrounded by desert and mallee. Its relatively high rainfall and hilly topography provide habitat for many threatened species and declining vegetation types. The region is home to many endemic species.

The Mediterranean biome includes the bioregions of:

  • Central Ranges
  • Eyre Yorke Block
  • Great Victoria Desert
  • Hampton
  • Kanmantoo
  • Murray-Darling Depression
  • Naracoorte Coastal Plain
  • Riverina
  • Victorian Volcanic Plain.
2.3.3 The Marine Biome

The coastal, estuarine and marine environments make up the marine biome. The marine biome includes variable and diverse currents around the coast with low nutrient, sheltered salty gulf waters; warmer waters of the Bight; and cooler nutrient rich waters of the south east. In the marine biome there are rough-water rocky shores and sub-tidal reef systems, sandy beaches, marine wetlands, extensive calm water mud flats, kelp forests, intertidal sandy flats, estuarine wetlands and sand dunes, seagrass, salt marsh and mangrove forest habitats.

South Australia's waters are amongst the most biologically diverse in the world. They provide habitat for a massive variety of plants and animals, including internationally and nationally important species such as Southern Right Whales, Australian Sea Lions, dolphins and Leafy Seadragons. Our waters support more than 6000 invertebrate species, 1200 types of algae, 350 fish species, 16 breeding seabird species, 33 mammal species and 12 seagrass species. In the Southern Ocean, 75% of the red algae, 85% of the fish species and 95% of seagrasses are found nowhere else in the world, giving them local, national and international significance. In comparison, the Great Barrier Reef shares more than 80% of its fish, coral reefs and other marine organisms with other countries in the tropics.

The Marine biome contains the bioregions of:

  • Coorong
  • Eucla
  • Eyre
  • Murat
  • North Spencer Gulf
  • Otway
  • Spencer Gulf
  • St Vincent Gulf.
2.4 Habitat

Habitat is the natural environment where an animal, plant or organism lives. An animal’s habitat includes a place to shelter and rear young and a reliable source of food and water. A plant’s habitat will have conditions suited to growing and reproducing, such as an adequate supply of nutrients, space, light and water.

Each living thing has its own unique habitat requirements within an ecosystem. For example, koalas spend most of their time in the canopy of gum trees. Their habitat does not include small shrubs, as they cannot eat the leaves, nor find adequate shelter from predators.

Species also vary in their space requirements. Sometimes this relates to the animal’s size. For example, hopping mice occupy very small territories, while kangaroos roam much larger areas. It can also depend on climate or the availability of food and water. As an example, the Red Kangaroo roams over large areas of arid Australia in search of grasses and plants. Its local distribution is often influenced by the availability of food, which is why, after a wet season, kangaroo numbers can grow rapidly in an area.

Animals often live and use more than one habitat type. Migratory species are an excellent example of this. Some species of water birds live in different places during different seasons and fly enormous distances to access seasonal food resources.

2.5 Connectivity

Connectivity encompasses the ways in which bioregions connect with each other that includes species and ecological processes interacting across different habitats or bioregions. Nature corridors provide important connections between fragmented and isolated habitats and are important for a number of reasons, such as maintaining species diversity, assisting migration and providing animals with room to move if the health of their habitat is changed. For these reasons it is critical to conserve connectivity both within and between bioregions.

Another aspect of connectivity is recognising and understanding how we are all connected to and dependent on each other and the earth. Urbanisation is a relatively recent phenomenon. In the previous 99% of human history, people lived a nomadic or agrarian existence in natural habitats. Currently more than 50% of the global population lives in urban areas and this figure is increasing every year, putting more pressure on biodiversity and ecological systems.

Because most of us live highly modified environments and are often removed from the original sources of our food and water, we lack an appreciation of how we are all interconnected with ecosystems. It is now better understood that the interconnections between each other and the natural world are vital to our lives and wellbeing.

2.6 Natural Systems

Nature is composed of integral often complex systems encased within other, larger systems. The biosphere (the whole planet) is a self-regulating closed system. Changes that occur within systems can affect not only the immediate system but also the systems nested within them and the larger systems around them. Within these systems communities of species are in dynamic relationships networking with each other and their environment. There is a continuous cyclic exchange of resources in the system as well as a continuous flow of energy from the sun. Each species in an ecosystem is needed to continue the entire food web. If these complex biological relationships break down, our basic needs, including our survival as a species, may not be met.