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.
Western Mallee is roughly defined as the western half of the Mallee biogeographic region. It has an area of 47,636 square kilometres, which is only lightly populated. The main towns are Hyden, Gnowangerup and Lake Grace; lesser towns include Kulin, Ongerup, Duggan, Newdegate, Lake King and Kondinin.
The subregion contains a number of ecologically important freshwater wetlands, including the Lake Bryde-East Lake Bryde wetlands, a DIWA Wetland of National Significance and habitat for a critically endangered threatened ecological community of shrub lake beds; the Lake Grace system of wetlands, also a DIWA Wetland of National Significance; and the Lake Cronin system. [1]
Western Mallee is situated on south-eastern parts of the Yilgarn Craton. It has a gently undulating landscape, with somewhat more relief than eastern parts of the Mallee region. There are a variety of soils, including clays and silts over kankar; sand; lateritic pavements; and granite outcrops. Gypsum dunes also occur in the area. The subregion has occluded drainage, with a number of lakes, both saline and fresh. [1]
Western Mallee is semi-arid, with a warm, dry, Mediterranean climate. It has seven to eight dry months, and a winter rainfall typically between 250 and 500 millimetres (10–19 in). [1]
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Year | ||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Mean daily maximum temperature | 33.5°C 92.3°F | 32.8 °C 91.0 °F | 29.8 °C 85.6 °F | 25.5 °C 77.9 °F | 20.6 °C 69.1 °F | 17.2 °C 63.0 °F | 16.3 °C 61.3 °F | 17.3 °C 63.1 °F | 20.2 °C 68.4 °F | 24.4 °C 75.9 °F | 28.2 °C 82.8 °F | 31.9 °C 89.4 °F | 24.8 °C 76.6 °F | |
| Mean daily minimum temperature | 15.3 °C 59.5 °F | 15.7 °C 60.3 °F | 14.1 °C 57.4 °F | 11.1 °C 52.0 °F | 7.7 °C 45.9 °F | 5.7 °C 42.3 °F | 4.7 °C 40.5 °F | 4.7 °C 40.5 °F | 5.9 °C 42.6 °F | 8.1 °C 46.6 °F | 11.4 °C 52.5 °F | 13.8 °C 56.8 °F | 9.9 °C 49.8 °F | |
| Mean total rainfall | 19.4 mm 0.76 in | 19.9 mm 0.78 in | 20.6 mm 0.81 in | 24.6 mm 0.97 in | 40.2 mm 1.58 in | 51.2 mm 2.02 in | 47.1 mm 1.85 in | 41.2 mm 1.62 in | 27.6 mm 1.09 in | 20.8 mm 0.82 in | 17.7 mm 0.70 in | 13.5 mm 0.53 in | 334.9 mm 13.19 in | |
| Mean number of rain days | 2.2 | 2.1 | 2.2 | 3.4 | 5.9 | 8.2 | 9.0 | 7.7 | 5.6 | 3.9 | 2.8 | 2.1 | 55.1 | |
| Source: Bureau of Meteorology [2] | ||||||||||||||
Only about 30% of the subregion retains its native vegetation. Within this area, most soil types carry mallee communities consisting primarily of Eucalyptus species. Sands and laterites support scrub-heath of Myrtaceae and Proteaceae, and the finer-textured soils support Eucalyptus woodlands; the latter have a particularly high diversity of flora, of which around 25% is rare. Granite outcrops also support a characteristic vegetation. [1]
There are also a number of vegetation communities of lesser extent, including some that are considered endangered or at risk. Most notable is the critically endangered community of Muehlenbeckia horrida subsp. abdita and Tecticornia verrucosa that occurs on the lake beds of the Lake Bryde-East Lake Bryde wetland system. Gypsum dunes support a vulnerable ecological community of herblands and bunch grasslands, and an at-risk community of Eucalyptus aff. incrassata over low scrub; at least 80 plant species are likely to occur only on gypsum dunes, including several threatened species. Some plant communities of the Bremer Range are also considered vulnerable. [1]
Information on Western Mallee's flora and fauna is scarce, as the area has not had a thorough biodiversity survey. What information is available has been gathered in the context of conservation assessment:
The subregion contains many endemic plant species in the Eucalyptus , Acacia , Proteaceae such as Grevillea , Hakea and Banksia ; and various Asteraceae. It contains numerous rare, endangered and priority flora. It also supports a number of rare or endangered fauna, including some that fall within the critical weight range for predation by foxes. The pig-footed bandicoot (Chaeropus ecaudatus) and crescent nailtail wallaby (Onychogalea lunata) previously occurred in the subregion, but both are now extinct. The rufous hare-wallaby (Lagorchestes hirsutus) is now extinct in the wild, and a further ten species of mammal are extinct in the subregion. The endangered red-tailed phascogale (Phascogale calura) still occurs in the region, as do the vulnerable black-flanked rock-wallaby (Petrogale lateralis) and heath rat (Pseudomys shortridgei), and the western brush wallaby (Macropus irma). [1]
Western Mallee falls within what the Department of Agriculture and Food terms the "Intensive Land-use Zone" (ILZ), the area of Western Australia that has been largely cleared and developed for intensive agriculture such as cropping and livestock production. Within this zone, the vast majority of land has been cleared for agricultural purposes. In Western Mallee's case, only 31% of the area retains its native vegetation. [3]
Around 10% of the subregion is held within nature reserves for conservation purposes, [1] covering about 25% of the remaining vegetation. [3] There is also a small amount of gypsum mining, and a tourist industry centred on Wave Rock near Hyden. The subregion contains populations of Eucalyptus and Melaleuca species that produce commercial quantities of cineole oil, so in future the subregion is likely to support a plantation-based oil mallee industry, at least as a source of breeding material if not also land. [1]
The subregion's nature reserves are poorly managed. Little information is available for management purposes, as the subregion has not had a thorough biodiversity survey, vegetation mapping is available only at 1:250,000 scale, and there are virtually no historical records of fires or other significant events. Other than routine baiting of foxes in some reserves, there is little done to manage threats. The main threat, rising salinity, is completely unmanaged, despite having already caused widespread population declines and extinctions in lowland communities. [1]
The subregion was given a Continental Stress Class of 3 when measured against the criteria, but the authors of that assessment stated that it should more properly be rated at 2 or even 1, because of the poor connectivity of reserves within cleared areas. [1]
Western Mallee was introduced in IBRA Version 6.1. Its region code is MAL2. It is one of two subregions of the Mallee region, the other being Eastern Mallee. [4] The Mallee, Avon Wheatbelt and Geraldton Sandplains regions together comprise Hopper's Transitional Rainfall Zone of Beard's South West Botanical Province. [5] [6] Under the World Wide Fund for Nature's regionalisation of the world's terrestrial surface into "ecoregions", the Western Mallee subregion falls within the Esperance Mallee ecoregion, one of 6 ecoregions comprising the Southwest Australia ecozone.
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.
The Interim Biogeographic Regionalisation for Australia (IBRA) is a biogeographic regionalisation of Australia developed by the Australian government's Department of Sustainability, Environment, Water, Population, and Communities. It was developed for use as a planning tool, for example for the establishment of a national reserve system. The first version of IBRA was developed in 1993–94 and published in 1995.
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 Swan Coastal Plain in Western Australia is the geographic feature which contains the Swan River as it travels west to the Indian Ocean. The coastal plain continues well beyond the boundaries of the Swan River and its tributaries, as a geological and biological zone, one of Western Australia's Interim Biogeographic Regionalisation for Australia (IBRA) regions. It is also one of the distinct physiographic provinces of the larger West Australian Shield division.
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.
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.
Esperance mallee is an ecoregion on the south coast of Western Australia, a coastal strip where the predominant vegetation consists of short eucalyptus trees and shrubs.
Lake Bryde-East Lake Bryde is a DIWA-listed freshwater wetland system located in the Great Southern region of Western Australia. The system consists of two lakes: Lake Bryde, with an area of 50 hectares ; and East Lake Bryde, with an area of about 1.4 square kilometres (0.54 sq mi). They are located at the head of a chain of lakes that extend to Lake Magenta, and ultimately form part of the Swan-Avon drainage system.
Eastern Mallee is an Interim Biogeographic Regionalisation for Australia (IBRA) subregion in southern 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.
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.
The Brigalow Belt is a wide band of acacia-wooded grassland that runs between tropical rainforest of the coast and the semi-arid interior of Queensland, Australia. The Interim Biogeographic Regionalisation for Australia (IBRA) divides the Brigalow Belt into two IBRA regions, or bioregions, Brigalow Belt North (BBN) and Brigalow Belt South (BBS). The North and South Brigalow Belt are two of the 85 bioregions across Australia and the 15 bioregions in Queensland. Together they form most of the Brigalow tropical savanna ecoregion.
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.
The Eyre Yorke Block, also known as the Eyre and Yorke mallee, is an interim Australian (IBRA) bioregion and a World Wildlife Fund ecoregion covering part of the Eyre Peninsula and all of Yorke Peninsula as well as land to its immediate east in South Australia.
The Tirari–Sturt stony desert is a deserts and xeric shrublands ecoregion in central Australia.
{{cite journal}}: Cite journal requires |journal= (help)CS1 maint: multiple names: authors list (link)