Murray Darling Depression

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Murray Darling Depression
Murray-Darling woodlands and mallee
LittleDesert.jpg
IBRA 6.1 Murray Darling Depression.png
The IBRA regions, with Murray Darling Depression in red
Ecology
Realm Australasian
Biome Mediterranean forests, woodlands, and scrub
Borders
Geography
Area197,900 km2 (76,400 sq mi)
Country Australia
States New South Wales, South Australia, and Victoria
Coordinates 35°12′S141°36′E / 35.2°S 141.6°E / -35.2; 141.6 Coordinates: 35°12′S141°36′E / 35.2°S 141.6°E / -35.2; 141.6
Conservation
Conservation status Critical/endangered
Protected31,000 km² (15%) [1]

The Murray Darling Depression , also known as the Murray-Darling woodlands and mallee, is a 19,717,651 HA biogeographic region and an ecoregion in southeastern Australia consisting of a wooded plain through which flow two of Australia's biggest rivers, the Murray and the Darling. There are several modern human settlements in the bioregion including Ivanhoe and Manilla, but the region also contains some of the oldest known human occupation sites in Australia. [2] [3] [4]

Contents

Environment

The plains have a dry Mediterranean climate with more rainfall (400mm per year) in the south than in the drier north (250mm). Fires are common in the hot dry summers. [5]

Wetlands

The depression is home to numerous wetlands which are in turn home to many rare and endangered animal and plant species. Major wetlands within the bioregion include the Darling Anabranch Lakes, Conoble Lake, Lake Victoria, Willandra lakes, and Gunnaramby Swamp. [6]

Flora

The original vegetation of the basin was mallee eucalyptus woodlands with thicker black box ( Eucalyptus largiflorens ) and river red gum ( Eucalyptus camaldulensis ) woodland on riverbanks but most has been cleared for wheat farming and pasture. The flora of the plain need to be adapted to renew itself after the summer droughts and accompanying fires.

Austrostipa nullanulla, an endangered type of spear grass, has been identified as regionally endemic to the nearby areas. [7] Several other rare plant species such as the Eriocaulon australasicum, and the Codonocarpus pyramidali are found here and considered to be relict populations. [7]

Fauna

Wildlife of the area includes large numbers of lizards, ants, and honeyeater birds (especially of the Lichenostomus and Meliphaga genera). Lizards include species of skink (especially of Ctenotus , Egernia , and Lerista genera). Ants include species of Iridomyrmex , carpenter ants, and Melophorus . Endangered species include the black-eared miner bird (Manorina melanotis) and the malleefowl (Leipoa ocellata).

Geology

Shallow seas moving across the plains several times over the last 50-60 million years have left a unique geological footprint in the area and geological records have indicated that at one point the seas coast stretched as far inland as modern day Balranald. In areas where the surface geology interact with the saline water table unique salt basins have formed. Lunettes can be observed along the edges of various lakes and swamps throughout the bioregion, these lunettes have kept record of the surrounding environment and have been used as evidence to demonstrate climate change in the area. [8]

Aboriginal history

Evidence of early human habitation dating back to at least 50,000 years can be found in the Willandra lakes region and concealed within the sand dunes surrounding Lake Mungo. [9]

Threats and preservation

Although much of the plain was cleared in the past (missing reference), this is now carefully controlled (missing reference) and areas of protected natural vegetation remain, especially in the large Ngarkat Conservation Park - Big Desert Wilderness Park on the South Australia-Victoria border. Threats to habitats today come from introduced weeds, over-salination of rivers as water is drawn off for irrigation, over-use of fire to remove dry shrubs and prevent forest fires and overgrazing by introduced goats and rabbits.

Related Research Articles

The Willandra National Park is a protected national park that is located in the Far West region of New South Wales, in eastern Australia. The 19,386-hectare (47,900-acre) national park is situated approximately 580 kilometres (360 mi) west of Sydney and comprises flat grassy plain bounded to the north by Willandra Creek, which is a tributary of the Lachlan River.

<span class="mw-page-title-main">Willandra Lakes Region</span> UNESCO World Heritage Site in New South Wales, Australia

The Willandra Lakes Region is a World Heritage Site in the Far West region of New South Wales, Australia. The Willandra Lakes Region is the traditional meeting place of the Muthi Muthi, Ngiyampaa and Barkinji Aboriginal tribes. The 240,000-hectare (590,000-acre) area was inscribed on the World Heritage List at the 5th Session of the World Heritage Committee in 1981.

<span class="mw-page-title-main">Esperance Plains</span> Bioregion in Western Australia

Esperance Plains, also known as Eyre Botanical District, is a biogeographic region in southern Western Australia on the south coast between the Avon Wheatbelt and Hampton bioregions, and bordered to the north by the Mallee region. It is a plain punctuated by granite and quartz outcrops and ranges, with a semi-arid Mediterranean climate and vegetation consisting mostly of mallee-heath and proteaceous scrub. About half of the region has been cleared for intensive agriculture. Recognised as a bioregion under the Interim Biogeographic Regionalisation for Australia (IBRA), it was first defined by John Stanley Beard in 1980.

<span class="mw-page-title-main">Mallee bioregion</span> Biogeographic region in southern Western Australia

Mallee, also known as Roe Botanical District, is a biogeographic region in southern Western Australia. Located between the Esperance Plains, Avon Wheatbelt and Coolgardie bioregions, it has a low, gently undulating topography, a semi-arid mediterranean climate, and extensive Eucalyptus mallee vegetation. It has an area of 73,975.59 square kilometres (28,562.13 sq mi). About half of the region has been cleared for intensive agriculture. Recognised as a region under the Interim Biogeographic Regionalisation for Australia (IBRA), it was first defined by John Stanley Beard in 1980.

<span class="mw-page-title-main">Western Mallee</span> Biioregion in Western Australia

Western Mallee is an Interim Biogeographic Regionalisation for Australia (IBRA) subregion in southern Western Australia. It is a sparsely populated subregion with an area of about 47,000 square kilometres, roughly centred on the town of Newdegate. Largely cleared for intensive agriculture, it still retains patches of native vegetation, but these are under environmental stress from threats such as rising salinity, and are poorly managed.

<span class="mw-page-title-main">Avon Wheatbelt</span> Bioregion in Western Australia

The Avon Wheatbelt is a bioregion in Western Australia. It has an area of 9,517,104 hectares. It is considered part of the larger Southwest Australia savanna ecoregion.

<span class="mw-page-title-main">Coolgardie bioregion</span> Bioregion in Western Australia

Coolgardie is an Australian bioregion consisting of an area of low hills and plains of infertile sandy soil in Western Australia. It has an area of 129,122.09 square kilometres (49,854.32 sq mi). It includes much of the Great Western Woodlands.

<span class="mw-page-title-main">Paroo-Darling National Park</span> Protected area in New South Wales, Australia

The Paroo-Darling National Park is a protected national park that is located in the Far West region of New South Wales, in eastern Australia. The 178,053-hectare (439,980-acre) national park spans two distinct regions in the outback area. This region covers the arid catchments of the Paroo River and the Paroo-Darling confluence to the south.

<span class="mw-page-title-main">Mulga Lands</span>

The Mulga Lands are an interim Australian bioregion of eastern Australia consisting of dry sandy plains with low mulga woodlands and shrublands that are dominated by Acacia aneura (mulga). The Eastern Australia mulga shrublands ecoregion is coterminous with the Mulga Lands bioregion.

<span class="mw-page-title-main">Southeast Australia temperate savanna</span>

The Southeast Australia temperate savanna ecoregion is a large area of grassland dotted with eucalyptus trees running north–south across central New South Wales, Australia.

<span class="mw-page-title-main">Coolgardie woodlands</span> Terrestrial ecoregion in Western Australia

The Coolgardie woodlands is an ecoregion in southern Western Australia. The predominant vegetation is woodlands and mallee scrub. The ecoregion is a transitional zone between the Mediterranean-climate forests, woodlands, and shrublands of Southwest Australia and the deserts and dry scrublands of the Australian interior.

<span class="mw-page-title-main">Mount Lofty woodlands</span> Ecoregion in South Australia

The Mount Lofty woodlands, or the Peppermint Box Grassy Woodland of South Australia is an ecoregion in South Australia, which includes woodlands, shrublands, and grasslands in the Mount Lofty Ranges, Fleurieu Peninsula, and Kangaroo Island.

<span class="mw-page-title-main">Naracoorte woodlands</span> Ecoregion in southern Australia

The Naracoorte woodlands is an ecoregion in southern Australia. It covers the Naracoorte coastal plain in southeastern South Australia and southwestern Victoria. It is coterminous with the Naracoorte Coastal Plain IBRA region. Only 10% of the ecoregion's area still has its original vegetation; most has been converted to agriculture and pasture.

<span class="mw-page-title-main">Yathong Nature Reserve</span> Protected area in New South Wales, Australia

The Yathong Nature Reserve is a protected nature reserve that is also a nationally and internationally recognized biosphere situated in the central-western region of New South Wales, in eastern Australia. The 107,240-hectare (265,000-acre) reserve was listed by UNESCO in 1977 as a Biosphere Reserve under the Man and the Biosphere Programme (MAB). The reserve is significant for its biodiversity in both native plant and animal species. Cultural heritage and historical grazing activities add to the significance of this site as a conservation area.

<span class="mw-page-title-main">Ecology of Sydney</span> Geographic aspect of Sydney, Australia

The ecology of Sydney, located in the state of New South Wales, Australia, is diverse for its size, where it would mainly feature biomes such as grassy woodlands and some sclerophyll forests, with a few pockets of mallee shrublands, subtropical and temperate rainforests (evergreen), heathlands, and wetlands. The combination of climate, topography, moisture, and soil influence the dispersion of these ecological communities across a height gradient from 0 to 200 metres. There are many hiking trails, paved and unpaved roads for exploring the many different biomes and ecosystems.

<span class="mw-page-title-main">Southeast Australia temperate forests</span> Terrestrial ecoregion in Australia

The Southeast Australia temperate forests is a temperate broadleaf and mixed forests ecoregion of south-eastern Australia. It includes the temperate lowland forests of southeastern Australia, at the southern end of the Great Dividing Range. Vegetation ranges from wet forests along the coast to dry forests and woodlands inland.

The Weeping Myall Woodlands is an endangered ecological community, under the EPBC Act of the Commonwealth of Australia. It is found in inland Queensland and inland New South Wales, on alluvial plains west of the Great Dividing Range. It takes its name from Acacia pendula, the weeping myall.

References

  1. Dinerstein, Eric; Olson, David; et al. (June 2017). "An Ecoregion-Based Approach to Protecting Half the Terrestrial Realm". BioScience. 67 (6): 534–545. doi: 10.1093/biosci/bix014 . PMC   5451287 . PMID   28608869.{{cite journal}}: CS1 maint: date and year (link) Supplemental material 2 table S1b.
  2. "Map of Ecoregions 2017". Resolve. Retrieved August 20, 2021.
  3. "Murray-Darling woodlands and mallee". Digital Observatory for Protected Areas. Retrieved August 20, 2021.
  4. "Murray-Darling woodlands and mallee". The Encyclopedia of Earth. Retrieved August 20, 2021.
  5. "Murray-Darling woodlands and mallee". Terrestrial Ecoregions. World Wildlife Fund.
  6. Morelli, Josephine (1996). A directory of important wetlands in South Australia. South Australian Dept. of Environment and Natural Resources. OCLC   39665062.
  7. 1 2 Cunningham, GM; Mulham, WE; Milthorpe, PL; Leigh, JH (2011). "Plants of Western New South Wales". doi:10.1071/9780643104273.{{cite journal}}: Cite journal requires |journal= (help)
  8. NSW Government. "Murray Darling Depression". NSW Environment and Heritage. Retrieved 2022-10-03.
  9. "Willandra Lakes | Heritage NSW". apps.environment.nsw.gov.au. Retrieved 2022-10-03.