| Avon Wheatbelt Western Australia | |||||||||||||||
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 The interim Australian bioregions, with Avon Wheatbelt in red | |||||||||||||||
| Area | 95,171.04 km2 (36,745.7 sq mi) | ||||||||||||||
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The Avon Wheatbelt is a bioregion in Western Australia. [1] It has an area of 9,517,104 hectares (23,517,280 acres). [2] It is considered part of the larger Southwest Australia savanna ecoregion. [3]
The Avon Wheatbelt bioregion is mostly a gently undulating landscape with low relief. It lies on the Yilgarn Craton, an ancient block of crystalline rock, which was uplifted in the Tertiary and dissected by rivers. The craton is overlain by laterite deposits, which in places have decomposed into yellow sandplains, particularly on low hills. Steep-sided erosional gullies, known as breakaways, are common. [4]
In the south and west (the Katanning subregion), streams are mostly perennial, and feed rivers which drain westwards to empty into the Indian Ocean. [4] In the centre, east, and north (Merredin subregion) there is no connected drainage. Here streams, which are remnants of ancient drainage systems, flow only during wet years, and drain to chains of salt lakes. [5]
It has within it two subregions named after localities within the region:
The bioregion has a semi-arid Mediterranean climate, with hot, dry summers and mild winters, with most rainfall occurring in the winter months. [5] The Avon Wheatbelt is generally drier than the Darling Scarp to the west.
Scrub-heath, characterized by shrubs in the Proteaceae family, are common on sandplains and lateritic uplands. These scrub-heaths are species-rich, and include many endemic plants. Mixed eucalypt woodlands with salmon gum ( Eucalyptus salmonophloia ) and rock sheoak ( Allocasuarina huegeliana ), and woodlands of jam ( Acacia acuminata ) and York gum ( Eucalyptus loxophleba ), are found on granite-derived soils and the alluvial soils of plains and stream valleys. There are smaller areas of wandoo woodland. [5]
The Wongan Hills are a range of flat-topped hills, dissected by steep gullies, in the northern portion of the bioregion. They are the largest area of intact vegetation in the northern Wheatbelt. The hills are home to remnant woodlands of salmon gum, York gum, gimlet ( Eucalyptus salubris ), and silver mallet ( Eucalyptus falcata ), and low forest of jam (Acacia acuminata), plant communities were once widespread but now rare in the Wheatbelt. The hills are home to 90 species of birds. Plants endemic to the Wongan Hills include Acacia botrydion, Acacia pharangites, Acacia pygmaea, Banksia bella, Eremophila ternifolia, Philotheca wonganensis , and Chenopodium aciculare . [5]
Granite outcrops, like Boyagin Rock, Kokerbin Rock, and Yilliminning Rock, are important as seasonal habitats and refuges for native fauna. Some are home to some endemic species, including the tree Eucalyptus caesia endemic to Boyagin Rock and the lichens Paraparmelia sammyi and Paraparmelia sargentii endemic to Yilliminning Rock. Granite pools are home to 350 species of aquatic invertebrates, including 50 thought to be endemic to the Wheatbelt. [5]
Native mammals include the red-tailed phascogale (Phascogale calura), black-flanked rock-wallaby (Petrogale lateralis lateralis), western brush wallaby (Macropus irma), and common brushtail possum (Trichosurus vulpecula). Several other once-native mammals are now locally extinct. [5] [4]
Native birds include malleefowl (Leipoa ocellata), Carnaby's black cockatoo (Calyptorhynchus latirostris), Baudin's black cockatoo (Calyptorhynchus baudinii), and Australian bustard (Ardeotis australis). [5] [4]
Toolibin Lake is an important breeding area for waterbirds in the inland drainage systems of south-western Australia, particularly freckled duck (Stictonetta naevosa). [4]
Much of the land is used for dryland farming, particularly wheat. Extensive areas have been converted to pasture for livestock grazing. [5] [4]
Less than 5% of the Avon Wheatbelt bioregion is in protected areas. [6]
The Wheatbelt is one of nine regions of Western Australia defined as administrative areas for the state's regional development, and a vernacular term for the area converted to agriculture during colonisation. It partially surrounds the Perth metropolitan area, extending north from Perth to the Mid West region, and east to the Goldfields–Esperance region. It is bordered to the south by the South West and Great Southern regions, and to the west by the Indian Ocean, the Perth metropolitan area, and the Peel region. Altogether, it has an area of 154,862 square kilometres (59,793 sq mi).
The Carnarvon xeric shrublands is a deserts and xeric shrublands ecoregion of Western Australia. The ecoregion is coterminous with the Carnarvon Interim Biogeographic Regionalisation for Australia (IBRA) bioregion.
Southwest Australia is a biogeographic region in Western Australia. It includes the Mediterranean-climate area of southwestern Australia, which is home to a diverse and distinctive flora and fauna.
The Murchison is a loosely defined area of Western Australia located within the interior of the Mid West region. It was the subject of a major gold rush in the 1890s and remains a significant mining district. The Murchison is also included as an interim Australian bioregion. The bioregion is loosely related to the catchment area of the Murchison River and has an area of 281,205 square kilometres (108,574 sq mi).
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.
Wongan Hills is a range of low flat-topped hills in the Avon Wheatbelt bioregion of Western Australia. It is located at 30°48′S116°37′E, in the Shire of Wongan–Ballidu.
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.
Warren, also known as Karri Forest Region and the Jarrah-Karri forest and shrublands ecoregion, is a biogeographic region in southern Western Australia. Located in the southwest corner of Western Australia between Cape Naturaliste and Albany, it is bordered to the north and east by the Jarrah Forest region. Its defining characteristic is an extensive tall forest of Eucalyptus diversicolor (karri). This occurs on dissected, hilly ground, with a moderately wet climate. Karri is a valuable timber and much of the karri forest has been logged over, but less than a third has been cleared for agriculture. Recognised as a region under the Interim Biogeographic Regionalisation for Australia (IBRA), and as a terrestrial ecoregion by the World Wide Fund for Nature, it was first defined by Ludwig Diels in 1906.
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.
Eastern Mallee is an Interim Biogeographic Regionalisation for Australia (IBRA) subregion in southern 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.
Hampton is an interim Australian bioregion located in southeastern coastal Western Australia, with a small portion (4%) extending into adjacent South Australia. It has an area of 1,088,198 hectares. The Hampton bioregion is part of the Coolgardie woodlands ecoregion.
Jarrah Forest, also known as the Southwest Australia woodlands, is an interim Australian bioregion and ecoregion located in the south west of Western Australia. The name of the bioregion refers to the region's dominant plant community, jarrah forest – a tall, open forest in which the dominant overstory tree is jarrah.
Yalgoo is an interim Australian bioregion located in Western Australia. It has an area of 5,087,577 hectares. The bioregion, together with the Avon Wheatbelt and Geraldton Sandplains bioregions, is part of the larger Southwest Australia savanna ecoregion as classified by the World Wildlife Fund.
Western Australia occupies nearly one third of the Australian continent. Due to the size and the isolation of the state, considerable emphasis has been made of these features; it is the second largest administrative territory in the world, after Yakutia in Russia, despite the fact that Australia is only the sixth largest country in the world by area, and no other regional administrative jurisdiction in the world occupies such a high percentage of a continental land mass. It is also the only first level administrative subdivision to occupy the entire continental coastline in one cardinal direction.
Eucalyptus drummondii, commonly known as Drummond's gum or Drummond's mallee, is a species of mallee or tree that is endemic to the southwest of Western Australia. It has smooth bark, narrow elliptical to egg-shaped adult leaves, flower buds in groups of seven, white flowers and hemispherical fruit.
The Einasleigh Uplands is an interim Australian bioregion, with vegetation consisting of savanna and woodland located on a large plateau in inland Queensland, Australia. It corresponds to the Einasleigh Uplands savanna ecoregion, as identified by the World Wildlife Fund.
Boyagin Rock is located 10 km (6.2 mi) south west of Brookton and 26 km (16 mi) north west of Pingelly in the Wheatbelt region of Western Australia, which is approximately 175 km (109 mi) south east of Perth. The Boyagin Rock outcrop rises 50 m (160 ft) above the surrounding land and is an crestal area of a granite inselberg within the geological Yilgarn Craton framework.
The Pilbara shrublands is a deserts and xeric shrublands ecoregion in Western Australia. It is coterminous with the Pilbara IBRA region. For other definitions and uses of "Pilbara region" see Pilbara.
Gawler is an interim Australian bioregion located in South Australia. It has an area of 12,002,883 hectares. Gawler bioregion is part of the Tirari–Sturt stony desert ecoregion.