Mulga Lands - biodiversity
As its name suggests, the predominant vegetation of the bioregion is mulga (Acacia aneura).
The eastern and northern parts of the bioregion support mulga, western bloodwood (Eucalyptus terminalis) and poplar box (Eucalyptus populnea), with mallee (Eucalyptus sp.), white cypress pine (Callitris glaucophylla), silver-leaf ironbark (Eucalyptus melanophloia), beefwood (Grevillea striata), leopardwood (Flindersia maculosa) and bluebush (Maireana sp.).
Spinifex (Triodia sp.) is found on the Block Range ridges. Few trees grow on the western stony plateaus.
Dense areas of woody shrubs extend across the sandplains. Mulga with ironwood (Acacia excelsa), white cypress pine, wilga (Geijera parviflora), gidgee (Acacia cambagei), brigalow (Acacia harpophylla), rosewood (Heterodendrum oliefolium), budda (Eremphila mitchellii), belah (Casuarina cristata) and sandhill wattle (Acacia ligulata) occupy sandplains, dunes and red soil rises.
Poplar box lines depressions in red country and occurs on the grey soil floodplains in the east.
Black box (Eucalyptus largiflorens), coolabah (Eucalyptus microtheca), river cooba (Acacia stenophylla), yapunyah (Eucalyptus ochrophloia) and eurah (Eremophila bignoniflora), together with lignum (Muehlenbeckia cunninghamii), canegrass (Eragrostis autralasica), saltbush (Atriplex sp.) and copperburr (Sclerolaena sp.) are typical of the alluvial clays, with some gidgee, leopardwood and wilga on claypan margins.
Sparse mulga can be found on lunettes.
Although there are no strictly endemic species in the Mulga Lands Bioregion, there are several significant flora species.
These include spiny sedge (Cyperus gymnocaulos), bore-drain sedge (C. laevigatus, found only between Milparinka and Wanaaring), smooth heliotrope (Heliotropium curassavicum) and Ellangowan poison-bush (Myoporum deserti) towards the east of the bioregion (Cunningham et al. 1981, Morton et al. 1995).
The bioregion also supports a Utricularia species, most likely the golden bladderwort Utricularia aurea, which has one or two records from the Paroo River but is mostly found along the coastal fringe of eastern Australia (Cunningham et al. 1981, Morton et al. 1995).
The salt pipewort Eriocaulon carsonii, listed as endangered in the TSC Act, has been identified as a relict species of the bioregion and is also found in SA and Qld (Briggs and Leigh 1995).
A review of fauna information in 1997 showed that 256 bird, 56 mammal, 94 reptile and 23 amphibian species have been recorded for the bioregion (National Land and Water Resources Audit). The eucalypt woodlands associated with riparian areas show the highest species richness (Sattler and Williams 1999).
The western quoll (Dasyurus geoffroii geoffroii), once believed to have been present in the bioregion, is presumed to be extinct. The greater bilby (Macrotis lagotis), night parrot (Pezoporus occidentalis) and plains rat (Pseudomys australis) are all believed to be Mulga Lands species that are endangered (Sattler and Williams 1999).
The Mulga Lands support similar faunal assemblages to other semi-arid bioregions in NSW. The woodlands of the bioregion are particularly important for avifauna, including the limited range species, the Hall's babbler (Pomatostomus halli).
Numbers of freshwater birds increased in this bioregion due to an increase in rainfall from the first survey period (1977-1981) and the second survey period (1998-2001), as did ground nesters, some seed-eaters and insect-eaters as well as some woodland species.
Grassland birds have not decreased significantly as is the trend in the majority of other bioregions (Australian Terrestrial Biodiversity Assessment 2002). Long-term trends indicate probable decline in bird species numbers as a result of ongoing land clearing in the bioregion.
Other significant fauna of the Mulga Lands is most often found in the wetlands of the bioregion, as detailed below.
There are six significant wetlands of the Paroo-Warrego area, which comprises the eastern half of the Mulga Lands Bioregion. All these wetlands are considered to be in good condition, providing habitat for large numbers of waterbirds.
Lower Bells Lake supports many waterbird populations, including the pink-eared duck (Malacorhynchus membranaceus) and grey teal (Anas gracilis), as well as providing nesting habitat for the black swan (Cygnus atratus).
The Cuttaburra Channels provide an important refuge for many waterbirds, sometimes to extreme numbers of up to 10,000 individuals.
The floodplain has provided nesting habitat for the Pacific black duck (Anas superciliosa), Pacific heron (Ardea pacifica), black swan (Cygnus atratus), whiskered tern (Sterna hybrida), red-necked avocet (Recurvirostris novaehollandia) and straw-necked ibis (Threskiornis aethiopica).
The Kichimiloo Claypan area is also thought to provide habitat for up to 10,000 waterbirds.
The Kerribree Creek floodplain supports the annual grass channel millet (Echinochloa inundata), which is considered to be rare and was used as grain by local Aborigines prior to European settlement (Vickery 1975, cited in Cunningham et al. 1981). This wetland has also been described as providing habitat for up to 20,000 waterbirds.
Another significant wetland is the Warrego River floodplain, which could support up to 14,000 waterbirds. However, like many other wetlands in the area, feral animals, exotic weeds and changed hydrology are slowly degrading the current habitat values.
The Warrego/Darling River confluence provides a home for the vulnerable barking owl (Ninox connivens) and red-tailed black cockatoo (Calyptorhynchus banksii) (Birds Australia/RAOU).
The vulnerable Major Mitchells cockatoo (Cacatua leadbeateri) and brolga (Grus rubicunda), and the endangered Australian bustard (Ardeotis australis) have all been recorded in the vicinity of this wetland.
Threats to these wetlands are feral animals, exotic weeds, water extraction, sedimentation and grazing pressure.
Other significant wetlands include Peery Springs and Paroo Wetlands, which have been identified as refugia for biodiversity in the bioregion (Morton et al. 1995).
Peery Springs are a pair of mound springs at the edge of Peery Lake towards the centre of the NSW part of the Mulga Lands Bioregion. These springs have remained active in a part of the Great Artesian Basin where, of the 45 springs in NSW, most are no longer actively flowing (Morton et al. 1995). These springs are now protected in Peery National Park.
The Paroo Wetlands are an enormous wetlands complex which are located on pastoral leases in the bioregion as well as being partly reserved in Nocoleche Nature Reserve which lies across this and the Darling Riverine Plains bioregions.
The wetlands are formed in swamps and playa lakes that are filled about every five years, when floodwaters flow southwest from Qld along the Paroo and Warrego Rivers and Cuttaburra Creek (Morton et al. 1995). These wetlands are threatened by changes to hydrology resulting from agriculture and vegetation changes caused by overgrazing (Morton et al. 1995).
These wetlands also provide habitat for large populations of waterbirds, many of which, such as the freckled duck (Stictonetta naevosa), are significant to the bioregion (Morton et al. 1995).
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Page last updated: 27 February 2011