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)

8.4. Riverina

Area

92,260 km².

Primary land-use

Sheep grazing, agriculture.

National Parks and Nature Reserves

Barmah State Park, Terrick Terrick State Park, Leaghur State Park.

Management problems

Land degradation through over-grazing (Benson 1991; Pickard 1991; Pickard and Norris 1994; Wilcox and Cunningham 1994). Birds of the chenopod shrublands appear to be particularly at risk of decline due to these effects (Reid and Fleming 1992). 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).

ANZECC-listed species

Birds: The core of the distribution of the plains-wanderer Pedionomus torquatus (V) lies in the Region (Baker-Gabb et al. 1990; Garnett 1992, pp. 48-49). Its conservation is dependent upon management of habitat to avoid cultivation, burning or over-grazing.

Fishes: The trout cod Maccullochella macquariensis (E) is endemic to the Riverina section of the Murray-Darling system (Lloyd et al. 1991; Wager and Jackson 1993; Douglas et al. 1994).

Plants: Maireana cheelii (V) (Cunningham et al. 1981).

Species that are regionally endemic

None identified.

Relict populations

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). In particular, the Macquarie perch Macquaria australasica has contracted on the western side of the Great Divide to certain streams in the Riverina, notably the Murrumbidgee and Lachlan Rivers (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: Remaining populations of masked owls Tyto novaehollandiae and bush thick-knees Burhinus grallarius are at risk (Smith and Smith 1994). Freckled ducks Stictonetta naevosa breed in the Region (Blakers et al. 1984). Smith et al. (1994) considered many waterbirds to be of conservation concern because of alterations to their habitats.

Reptiles: Populations of the elapid snake Notechis scutatus are declining in riverine habitats along the Murray-Darling system (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, and trout cod are endemic to the Murray-Darling system (Lloyd et al. 1991).

Wetlands

The following information is based on Wettin et al. (1993).

Booligal Wetlands: Wetlands occurring on the floodplains of the Merrimajeel and Muggabah Creeks, distributaries of the Lachlan River. Major wetlands include Booligal Swamp, Lower Gum Swamp, Murrumbidgil Swamp and Lake Merrimajeel. The creeks and channels are surrounded by lignum Muehlenbeckia cunninghamii and scattered stands of river red gum Eucalyptus camaldulensis, black box E. largiflorens and river cooba Acacia stenophylla. Several depressions along each of the creeks retain water after the creeks cease to flow. Large numbers of waterbirds congregate to breed and forage in the area during flood years, and so the Booligal wetlands provide valuable drought refuge habitat when wetlands in other parts of the inland are dry (Briggs and Maher 1985; Briggs et al.1985; Kingsford et al. 1990).

Merrowie Creek: Merrowie Creek is a distributary of the Lachlan River, leaving the river near Hillston, NSW. It consists of a series of weirs which pool water; beyond Cuba Dam the creek spreads into a series of channels before flowing into several large lake bodies, including Tarwong Lakes and Chillichil Swamp. Tarwong Lakes are a series of shallow depressions with a fringe of river red gum and surrounding black box and lignum. This area is inundated by floods to form an excellent waterfowl habitat. Large numbers of waterbirds, including the freckled duck Stictonetta naevosa, breed at Cuba Dam, Tarwong Lakes and Chillichil Swamp.

Millewa Forest: The wetland occurs on the floodplains of the Murray and Edward Rivers downstream of Deniliquin. The Murray is a regulated stream and has suffered some reduction in the frequency of flooding. The higher areas of the floodplain are forested with river red gums, while the low-lying marshes are dominated by rushes. Following flooding, large numbers of many species of waterbirds breed. Controlled inundation of extensive areas is practised so as to maintain the breeding of colonial nesting waterbirds following initiation of breeding by high winter-spring flows. The area is contiguous with Victoria's Barmah Forest which is presently listed on Ramsar.

Lake Brewster: A large shallow lake with patches of Typha located on the floodplain of the Lachlan River between Lake Cargelligo and Hillston. A valuable wetland supporting a high diversity of wildfowl including the freckled duck, which breed in this Lake. Because it is used as an off-river storage, it often retains water longer than surrounding natural lakes and so may offer refuge habitat.

Refugia

The Booligal wetlands are recognised as a refuge (see section 14.7).