Biodiversity publications archive

Refugia for biological diversity in arid and semi-arid Australia

Biodiversity Series, Paper No. 4
S.R. Morton, J. Short and R.D. Barker, with an Appendix by G.F. Griffin and G. Pearce
Biodiversity Unit
Department of the Environment, Sport and Territories, 1995

8. Foci of biological diversity in New South Wales (continued)

8.5. Murray-Darling Depression

Area

150,133km².

Primary land-use

Sheep grazing, agriculture.

National Parks and Nature Reserves

New South Wales: Mallee Cliffs National Park, Mungo National Park, Willandra National Park, Yanga Nature Reserve, Yathong Nature Reserve, Nombinnie Nature Reserve, Round Hill Nature Reserve, Pulletop Nature Reserve, Quanda Nature Reserve.

Victoria: Murray-Sunset National Park, Hattah-Kulkyne National Park.

South Australia: Calperum Reserve.

Management problems

Land degradation through over-grazing (Pickard 1991; Pickard and Norris 1994; Wilcox and Cunningham 1994); birds of the chenopod shrublands appear to be particularly at risk of decline (Reid and Fleming 1992). Fragmentation of mallee vegetation is a major conservation concern (Noble
et al. 1990; Mallee Vegetation Management Working Group 1991). Water quality in the rivers of the Region is declining rapidly, mainly as a result of removal of water for irrigation and from increased salinity caused chiefly by irrigation runoff (e.g. Helman and Estella 1983; Pressey and Harris 1988; Dendy and Coombe 1991; Richardson 1994; Sharley and Huggan 1994). Clearing for agriculture in marginal lands continues to be a problem (Benson 1991; Cambell 1994). Finally, control of vertebrate pests (Freudenberger 1993; Newsome 1994).

ANZECC-listed species

Birds: Malleefowl Leipoa ocellata (E) are under intensive management in NSW (Priddel 1990; Garnett 1992, pp. 32-4). Plains-wanderers Pedionomus torquatus (V) occur (Baker-Gabb et al. 1990; Garnett 1992, pp. 48-49). Black-eared miners Manorina melanotis (E) are confined to the Region and are at great risk of extinction (Garnett 1992, pp.133-4).

Plants: Parsons (1990) listed the following plants from the Victorian mallee: Halosarcia flabelliformis (V), Myriophyllum porcatum (V), Phebalium lowanense (V), and Lepidium monoplocoides (E). Fox (1991) listed Eriocaulon australasicum and Codonocarpus pyramidalis and Bowen and Pressey (1993) noted these as well as Stipa metatoris, Brachycome papillosa, Atriplex infrequens, and Swainsona pyrophila (all V) from New South Wales.

Species that are regionally endemic

Birds: The mallee emu-wren Stipiturus mallee is confined to fragmented mallee south of the Murray River in Victoria and South Australia (Garnett 1992, pp. 117-8). It is at risk because of clearance of habitat, fire, and grazing.

Plants: Stipa nullanulla (Bowen and Pressey 1993).

Relict populations

Noble et al. (1990) noted that mallee regions have undergone massive changes since European settlement through clearing, grazing, and altered fire regimes. Within the Murray-Darling Depression, virtually all mallee is now residual, as perhaps as much as 90% of mallee vegetation has already been cleared. Populations of many species are now too small or too isolated to remain viable; Noble et al. (1990) consider that now all remnants should be considered part of the conservation network. Parsons (1990) listed 13 rare or threatened plants from the Victorian mallee; including the ANZECC-listed species mentioned above, they are Epaltes tatei, Elachanthus glaber, Stipa nullanulla, Brachycome gracilis, Pterostylis xerophila, Spyridium spathulatum, Pimelea williamsonii, Swainsona laxa, and Phlegmatospermum eremaeum. He also reviewed cases of plant species which are not successfully regenerating and which persist only because the adult individuals are so long-lived. Fox (1991) listed Atriplex papillata and Swainsona laxa as rare or threatened species in New South Wales.

Many populations of the 29 species of fishes within the Murray-Darling system have contracted markedly due to dramatic changes in the rivers (Lloyd et al. 1991). The Murray hardyhead Craterocephalus fluviatilis was originally widespread in the Murray River system, but is now confined to small areas of the middle Murray (Wager and Jackson 1993).

Other significant populations

Mammals: Dickman et al. (1993) considered the greater long-eared bat Nyctophilus timoriensis and the yellow-bellied sheath-tail bat Saccolaimus flaviventris to be sparse and at risk because their tree-roosting behaviour exposed them to loss of habitat and predation by cats.

Birds: Populations of striated grasswrens Amytornis striatus striatus occur in mallee remnants throughout the Region (Garnett 1992, pp.119-20). Populations of the painted snipe Rostratula benghalensis are prominent in the Region (Garnett 1992, pp. 46-47). The eastern subspecies of the regent parrot Polytelis anthopeplus anthopeplus is at risk from clearance of mallee and loss of nest-trees (Garnett 1992, pp. 68-9). Freckled ducks Stictonetta naevosa breed in the Region (Blakers et al. 1984). Remaining populations of masked owls Tyto novaehollandiae and bush thick-knees Burhinus grallarius are at risk (Smith and Smith 1994). Smith et al. (1994) considered many waterbirds and the azure kingfisher Alcedo azurea to be of conservation concern because of alterations to their habitats.

Reptiles: The skink Ctenotus brachyonyx occurs in spinifex only in this Region and in the Simpson-Strzelecki Dunefields of north-western New South Wales and adjacent Queensland (Sadlier and Pressey 1994). Populations of the elapid snake Notechis scutatus are declining in riverine habitats along the Murray-Darling system, and the python Morelia spilota variegata is also declining in several vegetation types (Sadlier and Pressey 1994).

Frogs: The bell-frog Litoria raniformis appears to be contracting from its north-western margin (Sadlier and Pressey 1994).

Fishes: Two-spined blackfish Gadopsis bispinosus, Murray jollytail Galaxias rostratus, Australian rainbowfish Melanotaenia fluviatilis, Macquarie perch Macquaria australasica, Murray cod Maccullochella peeli, silver perch Bidyanus bidyanus are endemic to the Murray-Darling system (Lloyd et al. 1991).

Plants: Bowen and Pressey (1993) reported Lomandra patens, Glinus orygioides, Cratystylis conocephala, Olearia calcarea, Pachymitus cardaminoides, Atriplex papillata, Indigofera helmsii, and Solanum karsensis.

Wetlands

Great Cumbung Swamp and Lowbidgee Floodplain: The wetland comprises the terminal drainage swamp of the Lachlan River and its surrounding floodplain, together with the contiguous floodplain of the lower Murrumbidgee River near Balranald, New South Wales. Significant natural flooding occurs in about one in five years, and controlled annual flooding of large areas occurs during spring and summer as part of agricultural practices. The Great Cumbung Swamp comprises principally an area of common reed. The surrounding Lachlan floodplain and much of the Murrumbidgee floodplain are covered by woodland of river red gum Eucalyptus camaldulensis and black box E. largiflorens, with some areas of lignum Muehlenbeckia cunninghamii. This area would provide drought refuge when wetlands in other parts of the inland are dry. The system supports large numbers of waterbirds (including freckled ducks), many of which breed in the area ( Kingsford et al. 1990; Maher 1990).

Refugia

The Great Cumbung Swamp (see section 14.8) and the mallee remnants (14.9) are listed as refugia.