Commonwealth of Australia
Inclusion of ecological communities in the list of threatened ecological communities under section 181 of the Environment Protection and Biodiversity Conservation Act 1999 (EC 117)
I, TONY BURKE, Minister for Sustainability, Environment, Water, Population and Communities, pursuant to paragraph 184(1)(a) of the Environment Protection and Biodiversity Conservation Act 1999, hereby amend the list referred to in section 181 of that Act by:
including in the list in the critically endangered category
Natural Grasslands of the Murray Valley Plains
as described in the Schedule to this instrument.
Dated this…........28th............................day of…............August..........................2012
Minister for Sustainability, Environment, Water, Population and Communities
Natural Grasslands of the Murray Valley Plains
The Natural Grasslands of the Murray Valley Plains ecological community occurs on the plains of western and northern Victoria, extending into southern New South Wales. The grasslands are naturally treeless or almost so, with sparse tree cover. Most occurrences of the Natural Grasslands of the Murray Valley Plains ecological community are associated with Quaternary alluvial sediments, consisting of calcareous clay loams and clays on wetter sites, including self-mulching (cracking) clays. The ecological community is mainly restricted to the heavy-textured grey, brown and red clays.
The ecological community ranges from open to closed tussock grassland, but may also be dominated or co-dominated by a range of forb species, depending on seasonal conditions and management history. At other sites, the grassland may grade into an open grassy shrubland where low chenopod shrubs become co-dominant with the grass component. Trees and large shrubs are generally absent to sparse, amounting to less than 10% projective foliage cover for emergent trees or shrubs within a patch.
Species composition of the ecological community is strongly influenced by soil and climatic variables and there is, accordingly, a high degree of variation across the ecological community’s range. The composition of the ecological community also will vary depending on factors such as past and present grazing pressure as well as drought and rainfall patterns. Additionally, some species may not always be evident above-ground, but instead exist in the seedbank, or as dormant structures such as bulbs, corms, rhizomes or rootstocks in some seasons or under certain conditions.
Grasses are characteristically represented by one or more of the following genera: Rytidosperma (wallaby-grasses), Austrostipa (spear-grasses), Chloris (windmill grasses) and Enteropogon (windmill grass, spider grass).
Widespread perennial forbs may include Arthropodium spp. (vanilla lilies), Bulbine spp. (bulbine lilies), Calocephalus sonderi (pale beauty-heads), Chrysocephalum sp. 1 (recognised as C. apiculatum in NSW) (common everlasting), Leptorhynchos squamatus (scaly buttons), Minuria leptophylla (minnie daisy), Oxalis perennans (grassland wood-sorrel), Ptilotus nobilis subsp. nobilis (lambs-tails), Rhodanthe corymbiflora (paper sunray) and Sida corrugata (variable sida). Perennial herbs that are less widespread but are characteristic of the community include Calotis scabiosifolia (rough burr-daisy), Convolvulus angustissimus (pink bindweed), Plantago gaudichaudii (narrow-leaf plantain), Swainsona plagiotropis (red swainson-pea) and Wurmbea latifolia (broad-leaf early nancy). In higher rainfall areas of the ecological community or in depressions and wetter sites, Pycnosorus globosus (billy buttons) may be present.
Other important groups of native species in the ecological community include small annual forbs and small shrubs. The most common annuals are Eriochlamys behrii (woolly mantle), Goodenia pusilliflora (small-flowered goodenia), Isoetopsis graminifolia (grass cushion), Levenhookia dubia (hairy stylewort) and Triptilodiscus pygmaeus (common sunray). The most common small shrubs present are usually chenopods. Chenopods that characteristically occur in the ecological community may include: Atriplex semibaccata (creeping saltbush), Maireana decalvans (common bluebush), M. enchylaenoides (wingless bluebush), M. excavata (bottle bluebush), M. humillima (dwarf bluebush) and M. pentagona (slender bluebush).
The key diagnostic characteristics for the Natural Grasslands of the Murray Valley Plains are:
Distribution is primarily in the Riverina Bioregion and the Wimmera plains of the Murray Darling Depression Bioregion (as defined in version 6.1 of the Interim Biogeographical Regionalisation of Australia, IBRA). Other outlying occurrences are also in the Murray Darling Depression Bioregion and the NSW South Western Slopes Bioregion. The approximate northern limit of the ecological community is in the Murrumbidgee subregion (IBRA RIV2), near the northern boundary of the Murray Catchment Management Authority (CMA) in NSW (as at 2012).
It typically occurs on a landscape of flat alluvial lowland plains with heavy-textured grey, brown and red clays. The ecological community is typically dominated by a range of perennial grasses and/or forbs or co-dominated by small shrubs. Sites are not necessarily dominated by any particular plant species. Characteristic genera present typically include:
for grasses – Rytidosperma (formerly Austrodanthonia), Austrostipa, Chloris and Enteropogon. for forbs – Arthropodium, Bulbine, Calotis, Chrysocephalum, Leptorhynchos, Minuria, Ptilotus, Rhodanthe, Sida and Swainsona.
o for small shrubs – Atriplex and Maireana.
Trees and large shrubs (>1 m tall) are generally absent to sparse, amounting to less than 10% projective foliage coverfor emergent trees or shrubs.