The Simpson Desert is one of the world’s largest deserts of longitudinal dunes. It contains 1100 dunes arranged in a closely packed array, with some dunes running south-east to north-west for 200 km. Dunes can reach 90 m in height.
The Simpson and Strzelecki deserts form the Simpson–Strzelecki Dunefields (SSD) bioregion, comprising long parallel sand dunes, fringing dunefields, extensive sandplains, dry watercourses and saltpans. The arid dunefields and sandplains support sparse shrubland and spinifex hummock grassland, with cane grass on deep sands along dune crests. The swales of claypans and stony plains support a sparse shrubland of acacias, and coolabah woodlands fringe the creeks and floodouts.
Most of the SSD bioregion that lies within South Australia is within nature reserves, with over 3.5 M hectares held within the Munga-Thirri-Simpson Desert Conservation Park and Regional Reserve. One million hectares of the Queensland section of the Simpson Desert is held within the Munga-Thirra National Park.
The Simpson Desert extends across 180,000 square kilometres of land that straddles the border area Northern Territory, Queensland and South Australia.
The SSD bioregion has an arid, subtropical climate and includes the driest area of Australia. Rainfall is unreliable but usually occurs in summer storms. The median annual rainfall (1890–2005) averaged across the entire bioregion is 125 mm.
Arabana, eastern, southern and lower Arrernte, Dieri, Wangkamadla and Wangkangurra Yarluyandi lands.
Flora and fauna
The vegetation of the Simpson Desert is predominantly spinifex hummock grasslands with sparse acacia shrublands and some narrow river red gum (Eucalyptus camadulensis) and coolibah (E. coolabah) riverine woodlands. Sandhill canegrass (Zygochloa paradoxa) and sandhill wattle (Acacia ligulata) cover the dune crests and mobile slopes, while hard spinifex (Triodia basedowii) grows on stable slopes and the sandy corridors between dunes. Various species of acacia, eremophila and grevillea are found with these grasses. Low woodlands or tall shrublands of coolibah, Georgina gidgee (Acacia georginae), mulga (A. aneura) and other acacias and hakeas are found in the less sandy dune corridors. Low open shrublands of saltbush (Atriplexspp.) and bluebush (Maireana) are also present.
The fauna of the Simpson Desert is perhaps the most well understood of all of Australia’s deserts. The Eyrean grasswren (Amytornis goyderi), once thought to be extinct, is sparsely distributed across the Simpson Desert. The desert is important habitat for Ampurta/crest-tailed mulgara (Dasycercus cristicauda), kowari (Dasyuroides byrnei) and Wilkiniti/dusky hopping mouse (Notomys fuscus).
Threatened or vulnerable species found within the Simpson Desert include:
- Sea heath (Frankenia plicata)
- Slender Darling pea (Swainsona murrayana)
- Ampurta/Crest-tailed mulgara (Dasycercus cristicauda)
- Itjaritjara/southern marsupial mole (Notoryctes typhlops)
- Wilkiniti/dusky hopping mouse (Notomys fuscus)
- Plains mouse (Psuedomys australis)
- Eyrean grasswren (Amytornis goyderi)
- Grey grasswren (Amytornis barbatus)
- Australian bustard (Aredeotis australis)
- Grey falcon (Falco hypoleucos)
- Painted honeyeater (Grantella picta)
- Plains wanderer (Pedionomus torquatus)
- Woma python (Aspidites ramsayi)
Ten plant species and sixteen animal species found within the Simpson Desert are listed as rare or vulnerable in South Australia.
Introduced predators such as red foxes and feral cats have been a primary cause of the extinction of small-to medium-sized mammals across Australia’s arid inland. Along with wild dogs, they continue to pose significant threats to mammals, reptiles and ground-dwelling birds across all of Australia’s desert ecosystems.
Introduced herbivores such as camels, donkeys, horses and rabbits cause significant damage to desert ecosystems through overgrazing, particularly around water sources where they tend to congregate in dry times. Camels foul waterholes and have significant impacts upon fragile salt lake and freshwater ecosystems. The Simpson Desert has a high density of camels, particularly in the Northern Territory and South Australian sections.
Invasive species in particular buffel grass (Cenchrus ciliaris) poses the greatest threat to Australia’s desert ecosystems as it can quickly come to dominate the ground layer of vegetation. It burns hotter and more quickly than the native grasses it replaces. Buffel grass invasion in combination with larger and more intense wildfires driven by climate change have the potential to devastate the biodiversity of arid ecosystems.
High pasture utilisation of the interdune and drainage areas in the Queensland section of the Simpson Desert threatens vegetation by creating extensive areas of low cover that are prone to wind erosion.
Extraction and diversion of water from inland river systems reduces the water these areas receive and store, leading to the reduced health of waterholes, riverine and floodplain vegetation and the habitat they provide for fauna.