- Within the flat treeless Nullarbor Plain in South Australia and Western Australia.
- World's largest karst region characterised by solution sculpturing of outcrop, underground drainage systems and caverns.
- The population in the bioregion is extremely low with the main settlements being Yalata, Cook and Forrest.
- The bioregion includes pastoral leases, conservation reserves, Aboriginal land and part of the Woomera Prohibited Area.
- Pastoral leaseholds for sheep grazing cover about one-third of the bioregion.
- Hot dry summers and cold winters.
Statistical Local Areas
The Nullarbor bioregion lies within the flat treeless Nullarbor Plain. The bioregion includes land within South Australia and Western Australia, totalling 197,200 sq. kms. The majority of the bioregion (70%) lies within Western Australia. The south-eastern margin of the bioregion forms part of the Great Australian Bight coastline. The population in the bioregion is extremely low. There are several small settlements at regular intervals along the Trans Australian Railway. Kitchener is the westernmost of these and Ooldea is at the eastern margin of the bioregion. The bioregion has hot dry summers and cold winters.
The Nullarbor bioregion has a semi-arid climate with mild winters. Anti-cyclone systems moving from west to east across southern Australia control the summer weather pattern. The summer is extremely variable. Hot days with daytime temperatures exceeding 40°C can be followed by mild cloudy days in the low 20's. Summer rainfall is unreliable, usually comprising localised heavy showers or coastal drizzle. The mean summer temperature ranges from 18.2°C - 32.9°C.
Winter climate is affected by northerly moving low-pressure systems off the Southern Ocean. The winter mean temperatures range from 4.4°C - 13.8°C. The Nullarbor coastal area receives winter rainfalls. By the time the system reaches the Nullarbor interior it is usually devoid of rain, rarely do low-pressure systems provide significant winter rainfall. The annual mean rainfall is generally between 100mm and 200mm across the bioregion.
Climate averages are available for Cook (SA) and Forrest (WA):
For monthly rainfall and temperature graphs refer to Bureau of Meteorology website: www.bom.gov.au/climate/forms/map_forms/new_imagemaps/sa_name.html,
Current seasonal conditions and their historical context can be provided by satellite imagery. The Normalised Difference Vegetation Index (NDVI) is a measure of the vegetation 'greenness'. The NDVI for the Nullarbor bioregion for this year and previous years can be found at: http://www.ea.gov.au/land/monitoring/ttrace/nul.html.
For background information and additional NDVI products refer to: http://www.ea.gov.au/land/monitoring.
The Nullarbor bioregion comprises the Nullarbor Plain. It forms the onshore part of the Eucla Basin, one of the world's largest karst regions. There is considerable international interest in the development of karst features in arid settings. The karst landforms are characterised by solution sculpturing of outcrop, underground drainage systems and caverns.
The Eucla Basin formed part of the Miocene (less than 65 million years ago) sea-floor, which was subsequently uplifted to form the present day plateau. The surface is gently undulating, and any change in the surface relief is due to karst development. The landscape is occasionally interrupted with 'dongas', shallow circular depressions with sufficient soil and localised drainage to support scattered small trees or large shrubs.
For more detailed geological information and map refer to the Australian Geological Survey Organisation website: www.agso.gov.au/map/ and the Primary Industries and Resources South Australia: http://www.pir.sa.gov.au/dhtml/ss/section.php?sectID=5&;tempID=18&;force=1.
The soil type across the Nullarbor bioregion is uniform due to the uniformity of the underlying geological units. The typical soil type is shallow calcareous loamy soils. There are no permanent watercourses within the bioregion.
For further information on soils refer to Digital Atlas of Australian Soils at: www.brs.gov.au/data/datasets/atlas/index.html
The treeless plain of the bioregion is dominated by bluebush (Maireana spp.) and saltbush (Atriplex spp.). The peripheral areas to the north are characterised by low open woodlands of western myall (Acacia papyrocarpa) over pearl bluebush (Maireana sedifolia) (Thackway, 1995). The southern coastal strip and eastern margins are colonized by mallee (Eucalyptus yalatensis and E. socialis).
The 'dongas' or depressions support weeping pittosporum (Pittosporum phylliraeoides), dead finish (Acacia tetragonophylaa) and wild plum (Santalum lanceolatum).
The South Australian Herbarium documented plant species along the Trans Australian Railway prior to 1940. The South Australian Pastoral Board (1975) undertook vegetation classification and mapping for the South Australian portion of the Nullarbor Plain. A vegetation map of Western Australia by Beard (1975) provides a vegetation classification for the region. For detailed vegetation description of the Western Australian portion of the bioregion refer to Beard (1990) and Mitchell, et. al. (1998).
Over 60 reptile species and 135 bird species have been recorded within the Nullarbor region. Records of mammals for the Nullarbor are scant. Studies have focused on particular mammals, such as the hairy-nosed wombat (Lasiorhinus latifrons) and the stick-nest rat (Leporillus conditor). There is evidence from subfossil material and early collections that there has been a change in mammal species in the Nullarbor region (Woinarski, et. al., in prep.). A recent survey documents 21 mammal species in the bioregion with 11 previously documented mammal species unrecorded and presumed to be now regionally extinct (McKenzie & Robinson, 1987). These species include the dasyurids (Antechinomys laniger, Dasycercus cristicauda and Dasyurus geoffroii), bandicoots (Macrotis lagotis and Perameles bougainville) and bettong (Bettongia lesueur and Bettongia peniciilata) (McKenzie & Robinson, 1987).
The Nullarbor caves provide refuge to a wide range of species. Large colonies of bats (Chalinolobus morios) breed in the Nullarbor caves. The cave dwelling masked owl (Tyto novaehollandie) has been observed in the bioregion. The Nullarbor caves are home to an evolutionarily relict species of troglobites and troglophiles (Morton, et. al., 1995). Davy, et. Al. (1992) documents the full bibliography of this unique fauna.
An assessment of rabbits and dingoes in the Maralinga atomic testing site in the northeast of the bioregion was undertaken by the Ecological Survey Unit in 1977 to determine the level of plutonium present in the body tissue (McKenzie & Robinson, 1987).
For more information on fauna refer to the bioregional wildlife survey for the Nullarbor region by McKenzie & Robinson (1987).
The Nullarbor bioregion contains pastoral leases, conservation reserves, Aboriginal land and part of the Woomera Prohibited Area. The Aboriginal land in the bioregion includes part of the Maraling Tjarutja and the Yalata Land Holdings (McLennan, 1997).
Conservation reserves include: Nullarbor National Park (SA, 231,900 ha), Nullarbor Regional Reserve (SA), Yumbarra Conservation Reserve (SA), Wahgunyah Conservation Reserve (SA) and part of the Great Victoria Desert Nature Reserve (WA, 2, 495,777 ha), Unnamed Conservation Park (SA, 2,132,600 ha), Plumridge Lake Nature Reserve (WA, 308, 990 ha) and Nuytsland Nature Reserve (WA).
The Great Victoria Desert Nature Reserve is the largest reserve in Western Australia and represents the driest part of the Nullarbor. The Nullarbor National Park was former pastoral land and is characterised by the extensive treeless plain. The largest conservation area in South Australia is the Unnamed Conservation Park in the north of the bioregion. The area is largely unaffected by humans and contain a variety of unique ecosystems. Plumridge Lake Nature Reserve preserves areas of myall (Acacia spp.) over bluebush (Maireana sedifolia) and areas of mulga (Acacia spp.) (Morton, et. al., 1995).
For more information on National Parks refer to the South Australian National Parks and Wildlife Service web site:
http://www.atn.com.au/parks/saparks.html and CALM web site: www.calm.wa.gov.au/national_parks/previous_parks_month/ppm_splash.html.
Much of the bioregion remains undeveloped (Woinarski, et. al., in prep.). Pastoral leaseholds for sheep grazing cover about one-third of the bioregion, mainly near the coastal margin in Western Australia (Woinarski, et. al., in prep.). Pastoralism is limited due to the lack of availability of bore water. Some salt lakes in the southeast of the region are mined for high-grade gypsum and salt. For more information on land use in the south-east area of the bioregion refer to the Far West Coast Soil Conservation District Board: http://www.soil.pir.sa.gov.au/html/nav_dist.htm.
About 17% of the Western Australian portion of the bioregion is conservation reserve. The South Australian portion of the bioregion comprises about 58% conservation reserves (including regional reserves) (Woinarski, et. al., in prep.).
Overgrazing is the main cause of land degradation in the region, which is limited to localised occurrences. The Western Australian portion of the bioregion has been impacted by a combination of rabbits, fire and drought (Woinarski, et. al., in prep.). A marker of this degradation is the elimination of perennial shrubs, especially chenopod (Maireana sedifolia) due to ring barking by rabbits. The Nullarbor region, especially the 'dongas', has suffered continuing degradation by rabbits and invasive weeds (McKenzie & Robinson, 1987). Cave damage is a potential problem resulting from uncontrolled visitors.
For information on the land condition for the Western Australia portion of the bioregion in 1974 refer to Mitchell, et. al., (1998).
There are several pest species established in the bioregion including mice, rabbits, foxes, cats and camels. Rabbits have been plentiful prior to the introduction of Rabbit Calicivirus Disease (RCD).
Invasive weeds such as ward's weed (Carrichtera annua) is spreading dramatically particularly in previously overgrazed or disturbed areas.
The major transport services within the bioregion are the Trans Australian Railway and Eyre Highway. There are several small railway towns along the railway, from west to east these include, Naretha, Rawlinna, Haig, Loongana, Forrest, Reid, Deakin and Cook. The main centre in the bioregion is Yalata with a population of 273 (O'Donoghue & McKennan, 1996). The Yalata Community has developed a management plan for the establishment of whale watching to draw tourists to the area.
The bioregion lies within the ATSIC region of Port Augusta and the associated regional council of Nulla Wimila Kutja (McLennan, 1997). For more information on the Aboriginal people of this region refer to Horton (1994) and the relevant websites in the reference list.
Beard, J. S. 1975, Nullarbor: the Vegetation of the Nullarbor Area, University of Western Australia Press, Nedlands, Western Australia.
Beard, J. S. 1990, Plant life of Western Australia, Kangaroo Press, Kenthurst, New South Wales.
Davy, A. G., Gray, M. R., Grimes, K. G., Hamilton-Smith, E., James, J. M., & Spate, A. P. 1992, World Heritage Significance of Karst and Other Landforms in the Nullarbor Region, Department of the Arts, the Environment and Territories, Commonwealth of Australia, Canberra, ACT.
Horton, D. R. 1994, The Encyclopedia of Aboriginal Australia, Aboriginal Studies Press for the Australian Institute of Aboriginal and Torres Strait Islander Studies, Canberra, ACT.
McKenzie, N. L. & Robinson, A. C. 1987, A Biological Survey of the Nullarbor Region, South and Western Australia in 1984, South Australian Department of Environment and Planning, Western Australia Department of Conservation and Land Management, Australian National Parks and Wildlife Service, Adelaide, South Australia.
McLennan, W. 1997, 1994 National Aboriginal and Torres Strait Islander Survey: Social Atlas, Australian Bureau of Statistics, Canberra, ACT.
Mitchell, A. A., McCarthy, R. and Hacker, R. B. 1988, A Range Inventory and Condition Survey of Part of the Western Australian Nullarbor Plain, 1974, ed. C, H. Trotman, Western Australian Department of Agriculture Technical Bulletin No. 47, Perth, Western Australia.
Morton, S. R., Short, J. & Barker, R. D. with an Appendix by Griffin, G. F. & Pearce, G. 1995, Refugia for Biological Diversity in Arid and Semi-arid Australia, Department of the Environment, Sport and Territories, Canberra, ACT.
O'Donoghue, L., & McKennan, W., 1996. National Aboriginal and Torres Strait Islander Survey 1994: Regional Statistics, Ceduna ATSIC Region. Aboriginal Torres Strait Islander Commission & Australian Bureau of Statistics.
South Australian Pastoral Board 1975, A Vegetation and Range Site Plan of the Arid Zone, South Australian Pastoral Board, South Australia.
Thackway R. and Cresswell I.D. (eds.) 1995, An Interim Biogeographic Regionalisation for Australia: A framework for setting priorities in the National Reserves System Cooperative Program, Version 4.0. Australian Nature Conservation Agency, Canberra, ACT.
Woinarski J., Fensham, R., Whitehead, P. & Fisher, A., with map production by Verhagen, C. in prep., Biodiversity in the Australian Rangelands: a Review of Changes in Status and Threatening Processes. Draft report prepared as a resource document for Project 3: Developing an Adaptive Framework for Monitoring Biodiversity in Australia's Rangelands, of the National Land and Water Resources Audit, Theme 4 (Rangelands monitoring) by the Tropical Savannas Cooperative Research Centre, Darwin, Northern Territory.
Aboriginal languages of Australia:
Aboriginal Studies WWW Virtual Library:
Aboriginal and Torres Strait Islander Commission (ATSIC):
Australian Geological Survey Organisation, Geology of Australia:
Bureau of Meteorology, Climate averages:
Bureau of Meteorology, Temperature/rainfall graphs:
Bureau of Rural Sciences, Digital Atlas of Australian Soils:
Connors G., Oliver B., & Woinarski, J., 1996. Bioregions in the Northern Territory: conservation values, reservations status and information gaps.
Conservation and Land Management, WA National Parks:
Environment Australia, Normalized Difference Vegetation Index (NDVI) information including bioregional information:
Far West Coast Soil Conservation District Board:
Landcare South Australia:
Primary Industries and Resources South Australia: www.pir.sa.gov.au/dhtml/ss/section.php?sectID=5&tempID=18&force=1.
South Australian National Parks and Wildlife Service:
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