Nature conservation

Biodiversity Reform

Murray Darling Depression - biodiversity

Plant communities

Typical sandplain species include rosewood (Heterodendrum oleifolium), white cypress pine (Callitris glaucophylla), narrow-leaf hopbush (Dodonea viscosa), punty bush (Cassia eremophila), belah, copperburrs (Sclerolaena sp.), black bluebush (Maireana pyramidata) and variable spear grass.

The dunes support diverse mallee (Eucalyptus sp.) communities with mixed shrubs and porcupine grass (Triodia pungens). Belah (Casuarina pauper), rosewood and variable spear grass (Stipa variabilis) occupy the swales.

Lakes and depressions all have clay floors, and vegetation relates to the presence or absence of salt and gypsum. Infrequently flooded freshwater lakes carry cane grass (Eragrostis australasica), lignum (Muehlenbeckia cunninghamii) and nitre goosefoot (Chenopodium nitrariaceum), with clumps of black box (Eucalyptus largiflorens) on the margins.

The vegetation on lunettes varies. Clean sands often have white cypress pine, while brown clayey sands support mallee with porcupine grass. Mixed sand and clay lunettes carry rosewood, belah, western pittosporum (Pittosporum phylliraeoides), narrow-leaf hopbush and bluebush.

The largest rocky hills, Maccullochs Range, carry mulga (Acacia aneura) dominated vegetation very similar to much of the Cobar Peneplain. Smaller hills have more of a mixture of local sandplain species and distant rocky slope species.

Significant flora

Stipa nullanulla, now Austrostipa nullanulla, has been identified as regionally endemic to the Murray Darling Depression Bioregion and is listed as endangered in the TSC Act 1995 (Bowen and Pressey 1993, cited in Morton et al. 1995).

Significant flora species in the bioregion include Austrostipa metatoris, Mossgiel daisy (Brachycome papillosa), Atriplex infrequens, and Swainsona pyrophila, all listed as vulnerable in NSW.

The bioregion also supports irongrass (Lomandra patens), found mainly within the Cobar Peneplain Bioregion, desert carpet-weed (Glinus orygioides), found mainly in the far northwest, bluebush daisy (Cratystylis conocephala), which is very rare in NSW, Olearia calcarea, found only near White Cliffs, sand cress (Pachymitus cardaminoides), Indigofera helmsii and Menindee nightshade (Solanum karsensis) (Bowen and Pressey 1993, cited in Morton et al. 1995, Cunningham et al. 1981).

Other significant species are the salt pipewort (Eriocaulon australasicum) and Codonocarpus pyramidalis (Fox 1991, cited in Morton et al. 1995) as well as Atriplex papillata near salt lakes and the yellow Darling pea (Swainsona laxa). These are considered to be relict populations and rare in NSW, although S. laxa also occurs near Menindee in the Darling Riverine Plains Bioregion (Cunningham et al. 1981).

Significant fauna

The malleefowl (Leipoa ocellata), which is listed as endangered in the TSC Act, is found throughout western NSW, including in the Murray Darling Depression Bioregion (Priddel 1990, Garnett 1992, cited in Morton et al. 1995). The plains-wanderer (Pedionomus torquatus), listed as vulnerable in the TSC Act, is found in this bioregion as well as in the Riverina Bioregion (Baker-Gabb et al. 1990, Garnett 1992).

Black-eared miners (Manorina melanotis) are listed as endangered in both state and Commonwealth legislation, as they are at great risk of extinction and, within NSW, are now found only in the Murray Darling Depression Bioregion (Garnett 1992, cited in Morton et al. 1995).

The preferred habitat of the black-eared miner is dense, undisturbed old-growth mallee, which has undergone widespread clearing in NSW since the arrival of European settlers. This has resulted in the species occupying more open habitat, which is the preference of the yellow-throated miner (Manorina flavigula). This in turn has promoted cross-breeding between the two species, reducing the occurrence of pure forms of the black-eared miner (NSW NPWS 1999a).

The endangered eastern subspecies of the regent parrot (Polytelis anthopeplus ssp. anthopeplus) is generally confined to areas where mallee occurs adjacent to riverine woodlands in both the Murray Darling Depression and Riverina bioregions (NSW NPWS 1999b).

With an estimated NSW population of about 500 individuals, the species is considered to be at risk due to loss of potential nesting trees with the clearing of river red gum (Eucalyptus camaldulensis) and mallee communities (NSW NPWS 1999b, Morton et al. 1995).

Bush thick-knees (Burhinus grallarius) are also considered to be at risk in the bioregion (Morton et al. 1995).

Although known to occur across most of NSW, the freckled duck (Stictonetta naevosa) is recorded as breeding in the wetlands of the Great Cumbung Swamp and Lowbidgee Floodplain in the Murray Darling Depression Bioregion and other nearby bioregions (Morton et al. 1995).

Many waterbirds in the bioregion and species such as the azure kingfisher (Alcedo azurea) are reported to be of conservation concern because of changes in their habitats (Morton et al. 1995).

Birds of the chenopod shrublands in the bioregion seem to be at risk of decline (Reid and Fleming 1992, cited in Morton et al. 1995).

Most of the extant eastern mallee (Eucalyptus sp.) and its former range (now mostly wheatfields) lies in the Murray Darling Depression Bioregion. There are several large and many small mallee remnants in the bioregion. Three bird species are found mostly or entirely in the long unburnt mallee in this bioregion; the red-lored whistler (Pachycephala rufogularis), the vulnerable mallee emu-wren (Stipiturus mallee) and the endangered black-eared miner (Manorina melanotis).

Major populations of the endangered eastern subspecies of regent parrot (Polytelis anthopeplus), which moves between mallee and river red gum vegetation, are found in the bioregion.

The western whipbird (Psophodes nigrogularis), the vulnerable malleefowl (Leipoa ocellata) and the endangered plains wanderer (Pedionomus torquatus), the range of which is centred on the Riverina, can also be found.

More than 4 per cent of birds observed in the bioregion are exotic species, including the Eurasian skylark (Alauda arvensis), European goldfinch (Carduelis carduelis) and the common starling (Sturnus vulgaris), all of which have adapted well to the agricultural landscapes of the bioregion.

Numbers of the musk lorikeet (Glossopsitta concinna) have increased in the bioregion, as have temperate forest and temperate woodland birds. Conversely, grassland, ground-nesting birds and ground-feeding insectivorous species have decreased in numbers.

The general trend in this bioregion is a gradual decline in numbers in isolated habitat fragments, and extinctions that occur in major mallee blocks during rare, large-scale fires. The future of many bird populations in the bioregion may be dependent on appropriate fire management as well as the restoration, expansion and linking of habitat fragments.

The skink (Ctenotus brachyonyx) inhabits spinifex grasslands in the Murray Darling Depression and Simpson-Strzelecki Dunefields bioregions in NSW and also occurs in Qld. Populations of the elapid snake (Notechis scutatus) are declining in riverine habitats along the Murray-Darling system, while the python (Morelia spilota variegata) also appears to be declining in several vegetation types (Sadlier and Pressey 1994, cited in Morton et al. 1995).

The distribution of the southern bell frog (Litoria raniformis) seems to be retracting from its northwestern limit (Sadlier and Pressey 1994, cited in Morton et al. 1995).

Significant wetlands

The Darling Anabranch Lakes provide large areas of habitat for waterbirds when inundated (ANCA 1996). The lakes are considered to be in a fair condition, although they are declining due to changed hydrology caused by salinity, water abstraction and regulation, weir construction upstream, construction of levee banks and lake bed cropping.

The Lowbidgee Floodplain has also been described as degraded although it provides an important refuge when other wetlands are dry, and it supports breeding colonies of Australian white ibis (Threskiornis molucca), glossy ibis (Plegadis facinellus), straw necked ibis (Threskiornis spinicollis), royal spoonbill (Platalea regia), great egret (Casmerdius albus) and intermediate egret (Egretta intermedia) (ANCA 1996).

Conoble Lake is a significant wetland of the bioregion, and is predicted to be able to support 11,000 waterbirds. There have been many sightings of the vulnerable Major Mitchell's cockatoo (Cacatua leadbeateri) near Conoble Lake, while two endangered plants, Kippistia suaedifolia and Dysphania plantaginella, have also been recorded.

Lake Victoria supports the endangered southern bell frog (Litoria raniformis), the vulnerable Major Mitchells Cockatoo and the endangered regent parrot (Australian Terrestrial Biodiversity Assessment 2002), as well as providing habitat for 20,000 waterbirds (Kingsford et al. 1997).

The Willandra Creek and Lakes is one of the most significant wetland areas in the bioregion, supporting a variety of threatened species even though it has been described as being in a degraded condition and declining (Australian Terrestrial Biodiversity Assessment 2002).

Many sightings have been recorded here including the blue-billed duck (Oxyura australis), freckled duck (Stictonetta naevosa), black-breasted buzzard (Hamirostra melanosternon), Australasian bittern (Botaurus poiciloptilus), Major Mitchells cockatoo, painted honeyeater (Grantiella picta), barking owl (Ninox connivens), little pied bat (Chalinolobus picatus), inland forest bat (Vespadelus baverstocki), stripe-faced dunnart (Sminthopsis macroura), long-haired rat (Rattus villosissimus), slender darling pea (Swainsona murrayana) and mossgiel daisy (Brachyscome papillosa).

Endangered species found at Willandra Creek include the southern bell frog (Litoria raniformis), Australian bustard (Ardeotis australis) and plains wanderer (Pedionomus torquatus) (Australian Terrestrial Biodiversity Assessment 2002).

Two other wetlands, which provide significant habitat for waterbirds but are currently described as being in a degraded condition are Gunnaramby Swamp and Moornanya Lake.

Gol Gol Lake (Benanee) lies partly in the Murray Darling Depression Bioregion but occurs mostly within the Riverina. Nettlegoe Lake and Poopelloe Lake fall partly in the bioregion but mainly in the Darling Riverine Plains Bioregion.

Threats to wetlands in the Murray Darling Depression Bioregion include feral animals, exotic weeds, salinity, water abstraction and regulation, and regulation producing perennial flooding (National Biodiversity Audit).

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Page last updated: 26 April 2016