Southeast Australia temperate savanna
Location and descriptionEdit
It is a dry area of low hills and valleys of which the southern section is the wheat-growing plain known as the Riverina and the northern section is low hills and plains mostly used for grazing sheep running north to the plains of the Darling River basin and the New South Wales–Queensland border. Rivers of the savanna include the Murray River and the Murrumbidgee in the south and the Darling River in the north. Rainfall is low and irregular, from 300–500 mm per year becoming less the further westward and inland you go.
The dry climate sustains hardy shrubs and grasses scattered with small patches of the bimble box and coolibah eucalyptus trees that once covered most of this part of Australia. The Riverina area nearer the coast contains red river gum and black box.
The effect of massive numbers of sheep on the grassland was dramatic and was noted by settlers in the grassland regions. The original soil of the grasslands was soft and absorbed rain readily, but heavy continuous stock grazing drove a degradation sequence that shifted the botanical composition of native grasslands from an ecosystem regulated by large, perennial tussock grasses such as Themeda triandra (Kangaroo Grass) to one containing abundant disturbance tolerant native grasses such as Rytidosperma spp.
These grasslands are the western limit for much of the wildlife that lives here as further west is desert. Wildlife of the savanna includes mammals such as the mouse-like kultarr marsupial (Antechinomys laniger), tiger quoll (Dasyurus maculatus), and brush-tailed rock-wallaby (Petrogale penicillata). The western barred bandicoot (Perameles bougainville fasciata) and bridled nail-tail wallaby that once lived here are now presumed extinct in New South Wales. Birds include the endangered bush stone-curlew (Burhinus grallarius), superb parrot (Polytelis swainsonii), red goshawk (Erythrotriorchis radiatus), malleefowl (Leipoa ocellata) and plains-wanderer (Pedionomus torquatus), and reptiles include an endangered skink Anomalopus mackayi. The Riverina grasslands are home to birds such as the freckled duck, and wintering populations of swift parrot (Lathamus discolor).
Threats and preservationEdit
Active preservation of habitats is required because much of the savanna has been converted to pasture or wheatland. This is particularly so in the Riverina where most has been cleared for wheat planting, a process that is ongoing, while the grasslands are vulnerable to overgrazing, and rivers including the Murray and Murrumbidgee are depleted by being water sources for large irrigation projects. As land is cleared it becomes habitat for invasive species such as noisy miner bird (Manorina melanophrys) and Australian raven (Corvus coronoides). The main protected area is the steep volcanic outcrops of Warrumbungle National Park. There are small areas of parkland elsewhere and plans to create more, but there are no large areas of original savanna under protection.
- Williams, Nicholas; Marshall, Adrian; Morgan, John, eds. (2015). Land of Sweeping Plains. CSIRO Publishing. ISBN 9781486300815.
- Hodgkins, D., D. Goldney, G. Watson, and G. Tyson. 2000. The attitudes of landholders to a range of environmental issues, including the values of remnant bushland in the central western region of New South Wales. Pages 336–350 in R. J. Hobbs and C. J. Yates, editors. Temperate Eucalypt Woodlands in Australia: biology, conservation, management, and restoration. Surrey Beatty & Sons, Chipping Norton, New South Wales, Australia
- "Southeast Australia temperate savanna". Terrestrial Ecoregions. World Wildlife Fund.