Natural Grasslands of the Murray Valley Plains is a community dominated by perennial tussock grasses and a large range of forbs. It differs from grasslands in more northern parts of the Riverina that are considered derived from grassy chenopod shrublands with dominant Maireana, Atriplex and Chenopodium spp. and Nitraria; or derived forms of the EEC “Myall Woodland in the Darling Riverine Plains, Brigalow Belt South, Cobar Peneplain, Murray-Darling Depression, Riverina and NSW South Western Slopes bioregions”.
The community Natural Grasslands of the Murray Valley Plains, which is not regarded as derived, is generally characterised by tussock grasses and forbs, the composition and abundance of which depends on soil, drainage, current and historic management, particularly grazing, seasonality and rainfall patterns. Dominant grasses include Rytidosperma spp., Chloris truncata and Austrostipa nodosa or A. scabra on well-drained red brown soils, while Enteropogon acicularis, Walwhalleya proluta and sometimes Austrostipa aristiglumis occur on grey clay soils on lower-lying areas. A broad range of forbs can dominate or exist in the inter-tussock spaces, include species of lilies such as Arthropodium and Bulbine, daisies such as Calotis, Chrysocephalum, Leptorhynchos, Minuria and Rhodanthe,as well as species of Swainsona, Ptilotus and Sida. Small shrubs such as Atriplex spp. and Maireana spp. may also be present. Trees and tall shrubs are generally absent, however where present may include Acacia oswaldii, A. pendula, Allocasuarina luehmannii and Eucalyptus spp. from intergrading communities. Anumber of flora species that occur in the community are listed under the NSWTSC Act or the Commonwealth EPBC Act, as vulnerable, endangered or critically endangered, including Goodenia macbarronii, Leptorhynchos orientalis, Maireana cheelii, Pterostylis despectans, Sclerolaena napiformis, Swainsona murrayana, Swainsona plagiotropis and Swainsona sericea.
Distribution
Natural Grasslands of the Murray Valley Plains occur in south-west NSW, bounded by Swan Hill in the west, just north of Conargo in the north and Lockhart in the East, down to the Victorian Border. Climatic range extends from temperate through to semi-arid. This community is also found extensively in Victoria.
Habitat and ecology
- Unlike other temperate grassland communities in south-eastern Australia, it occurs primarily on quaternary alluvial sediments of the Murray Valley plains, in areas with heavy-texture grey, brown and red clays, which favour grasslands rather than trees.
- Average annual rainfall ranges from approximately 300 to 500 millimetres with a gradient of increasing rainfall from north-west to south-east, although rainfall is highly variable from year to year. There is generally a small peak in rainfall during the winter.
- Much of this community has been cleared and what remains is often disturbed or degraded, however this TEC listing aims to protect patches that are functional, relatively natural and in relatively good condition.
- In its northern extent in NSW this community can be distinguished from grasslands derived from former Acacia pendula woodlands or chenopod shrublands through a comparative list of species tabled in the Listing Advice. Having a soil type and landscape position that correspond to the Listing, as well as there being no reliable evidence that an area was once woodlands or shrubland with > 10% cover are useful diagnostic features that help to identify this community.
- Condition thresholds specify that the percentage cover of perennial and annual native vascular plants should be greater than the cover of perennial exotic species. In addition small patches of a minimum of 0.04 hectares in size should have at least 15 native species and one or more indicator species (see Listing Advice); or in larger patches of at least 1 ha in size there should be at least 10 native species.
Regional distribution and habitat
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