Environment

Where Is The Nullarbor Plain?

The world's largest expanse of exposed limestone bedrock covers more than 75,000 square miles in southern Australia.

Description

The 270,000 square-kilometer Nullarbor Plain in Australia is the world’s largest limestone karst plain landscape. It has over 250 limestone caves with their own unique fauna, and has no known permanent surface water and trees. The plain is in one of nine diverse landscapes in the Alinytjara Wilurara Natural Resources Management (AW-NRM) region that covers the northwestern third of the state of South Australia, and is dedicated to the conservation and traditional Aboriginal use and habitation of the area, according to the South Australian Government's Department of Environment, Water, and Natural Resources. Nullarbor Plain spans 2,000 kilometers between Norseman town in Western Australia and Ceduna town in South Australia, according to the Wilderness Society (TWS) Australia. Two-thirds of the plain are in Western Australia, and the other third in South Australia.

Historical Role

Recent research conducted by the University of Melbourne implies that the now barren Nullarbor Plain was once covered by a forest that received four times the rain seen falling there today. That precipitation enabled the plain to support the growth of gum and eucalyptus trees, flowering plants, and banksia shrubs. But a dramatic climatic transformation that occurred about 5 million years ago caused the vegetation to change to its currently negligible state. Traces of ancient Aboriginal “art” have also been discovered recently in the Koonalda Cave in the Nullarbor Plain. These aboriginal markings, according to the Australian Heritage Council (AHC), date back to the Pleistocene age over 22,000 years ago. They help give us an understanding of the earliest years of Aboriginal occupation in Australia. The Kanoola Cave also helped confirm the Aboriginal people survived in the semi-arid region of the Nullarbor Plain during the last ice age, also according to AHC.

Modern Significance

Nullabor Plain best captures the Australian Outback experience for many of its tourists. Visitors to the plain go on self-driven tours across the plain on the Eyre Highway, and see the mallee vegetation dotting the plain along the way, including the salt-bush and blue-bush on the plateaus. The highway is named after John Eyre, the first white human to walk across the Nullarbor Plain in 1841. Along the route are kangaroo habitats and hotels where one can dine and lodge as they journey across the plain. Commercial grazing is also carried out on 32 percent of the Nullarbor bio-region, according to Australia’s Department of Environment.

Habitat and Biodiversity

Nullarbor Plain has a desert climate that’s arid to semiarid, with annual rainfall of between 150 and 250 millimeters. This sustains the treeless plains that are instead covered with salt-bush and blue-bush plants, and hardy shrubs that are drought-resistant and salt-tolerant, according to TWS. There also are Myall acacias on the edges of the Nullarbor Plain. Collectively, there are 794 vascular plant species, 56 mammal species, 249 bird species, 86 reptile species, and 1 frog species native to the plain. Nullarbor Plain’s birds of prey include the osprey, the White-bellied Sea eagle, and the Peregrine falcon. The endemic birds there include the Nullarbor quails and Nareth Blue Bonnet birds. Also, the largest Hairy-nosed wombat populations are found here, as well as the Dingoes and Nullarbor Bearded dragons. There are 11 threatened flora species, including the Nullarbor emu bushes, living here according to AW-NRM. When it rains or precipitates, water collects in circular depressions called dolines and rock holes.

Environmental Threats and Territorial Disputes

The fragile flora's biodiversity in the Nullarbor Plain is prone to the effects of off-road vehicle damage caused by visitors driving off of designated trails. Furthermore, overgrazing by commercial livestock decimates the vegetative cover of Nullarbor, according to the Encyclopedia of the Earth. The introduction of feral animals like cats, camels, foxes, and rabbits has caused ecological imbalances across the Nullarbor Plain. The rabbits eat young seedlings resulting in the decline of certain shrubs, hence affecting resident bird species and other wildlife dependent on the vegetative cover, according to TWS. Alien weeds also compete with and destroy the natural vegetation of the Nullarbor Plain.

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