Tanami Desert

Category: Desert Biomes.

Geographic Location: Australia.

Summary: This remote desert region is valued for its biological diversity, its vast new wildlife preserve, and its management by Aboriginal Australians.

Australia is the world’s driest continent after Antarctica; arid zones cover 65 percent to 75 percent of its landmass. Situated between Darwin in the north and Alice Springs in the south, and located in the Northern and Western Australia Territories, the Tanami Desert is one of the nation’s five major desert regions. Annual precipitation ranges from 8 to 16 inches (200 to 400 millimeters). Together with the neighboring Sandy Desert, Gibson Desert, and Central Ranges xeric (drought-tolerant) scrubland, the combined extent of ecoregion is vast—nearly 500,000 square miles (1.3 million square kilometers) of arid biomes.

Arid regions of Australia tend to have extensive sand dune formations. Underlying much of the Tanami bioregion is the Tanami dune field. The associated surface communities include sand plains, dune fields, and extensive hummock grassland habitats. Other landforms include alluvial plains, rocky hills and rises, clay pans, and freshwater and saline lakes. This habitat diversity contributes to high biological diversity, and the desert serves as a refuge for a variety of threatened species.

In addition to grasslands, which are often dominated by spinifex grasses in the genus Triodia, the region contains sparse shrublands, like those containing saltbush (Atriplex spp.), and open woodlands with many Acacia and Eucalyptus species.

Biodiversity

The Australia government considers the Tanami Desert to be one of the country’s most important landscapes for the protection of rare and endangered species. Mammalian species of interest include marsupials, such as the long-tailed planigale (Planigale ingrami) and bilby (Macrotis lagotis); and nonmarsupials, such as the western chestnut mouse (Pseudomys nanus) and little native mouse (P. delicatulus). The region has lost some small and medium-size mammals still found elsewhere in Australia, including the western quoll (Dasyurus geoffroii). Bird species of significance include the gray falcon (Falco hypoluecos) and the freckled duck (Stictonetta naevosa).

Despite its desert status, the region also houses a variety of aquatic habitats ranging from isolated desert water holes to larger lakes. Lake Gregory in the Western Australia Territory is a permanent water source and is considered to be a freshwater lake at times of high rainfall when it is full. In the Northern Territory, Lake Surprise, at the end of the Lander River, is the largest body of water in the Tanami Desert when its level is high. It is considered to be a critical resource for birds during times of drought.

Lake Gregory has been designated an Important Bird Area by Birdlife International because it supports more than 1 percent of the world’s population of at least six species. Approximately 100,000 to 600,000 individual waterbirds may be found there during many seasons. Elsewhere in the region, the Davenport and Murchison ranges contain waterholes that are critical resources for birds in times of drought. These catchments also hold species of fish of biogeographical significance because of their isolation from other river systems.

Human Settlement

Because of its remote location in north-central Australia, the Tanami was not fully explored by scientists until the twentieth century. However, Aboriginal occupation and management of the region are thought to extend back as far as 40,000 years, and continues into the present. Human population density is low, probably less than one person per 0.4 square mile (1 square kilometer). Modern land uses are grazing, mining, and various indigenous practices, including the harvesting of native plants and animals. Tourism has also become increasingly important.

Climate change threatens to alter this area significantly. The entire Australian Outback is receiving more annual precipitation than ever before, which could alter the size and scope of this desert habitat. Annual rainfall in some parts of the Tanami has doubled from the 1970s to the 2020s.

Environmental Threats

The most significant land-management issues in this region are land degradation due to grazing, fire, and the effects of nonnative species on the native flora and fauna. The Tanami Desert is of great national and international importance because of its high biological diversity value.

Site conditions vary considerably throughout the region. Where significant land-management issues occur, they mostly stem from one of three factors: grazing, fire, or invasive species. Grazing has its strongest negative effects near bodies of water, where livestock tend to congregate. Some grassland communities have also been degraded by grazing.

In combination with grazing, fire has negatively affected native vegetation. Fire is a natural and regular feature of this landscape; however, changes in traditional burning practices have resulted in a shift from frequent burning and small average fire sizes to less frequent burning that results in larger and more intense fires. This can inflict serious, long-lasting damage on habitats.

Several exotic vertebrate and plant pest species cause significant problems for native species and for human land use in the Tanami Desert. Non-native rabbits and foxes, as well as feral cats, cause problems for native flora and fauna as competitors, grazers, or predators of native species. At least 21 weedy plant species have been recorded here, including buffel grass (Cenchrus ciliaris), an invasive that is native to North Africa and the Middle East. This species has shown the capacity to outcompete native grasses and to increase the frequency of wildfires.

Despite these problems, the Australian Land Disturbance Database lists most of the Tanami as having high “biophysical naturalness and wilderness quality.” In 2012, the Australian government declared an immense southern swath of the Tanami Desert—nearly 25 million acres (10 million hectares)—a conservation zone. Easily the largest such area set aside in Australia, this desert-and-savanna reserve was established to help the stabilization and recovery of such endangered species as the bilby and the great desert skink, a burrowing lizard. Aboriginal rangers will manage this new sanctuary, dubbed the Southern Tanami Indigenous Protected Area.

Bibliography

“The Australian Desert And Climate Change.” Outback Australia Travel Guide, 2022, www.outback-australia-travel-secrets.com/australian-desert.html. Accessed 30 Aug. 2022.

Kelly, K. Tanami—On Foot Across Australia’s Desert Heart. Sydney, Australia: Pan Macmillan, 2003 .

Morton, S. R., J. Short, and R. D. Barker. Refugia for Biological Diversity in Arid and Semiarid Australia, Biodiversity Series Paper No. 4. Canberra, Australia: Department of Environment and Heritages, 2004 .

Newell, Janet. “The Role of the Reintroduction of Greater Bilbies (Macrotis Lagotis) and Burrowing Bettongs (Bettongia Lesueur) in the Ecological Restoration of an Arid Ecosystem: Foraging Diggings, Diet, and Soil Seed Banks.” Research Theses of the School of Earth and Environmental Sciences, University of Adelaide (2009).