Evidence for the natural occurrence of treeless grasslands in the Riverina region of south-eastern Australia
Keith L. McDougallPresent address: NSW Department of Environment and Climate Change, PO Box 733, Queanbeyan, NSW 2620, Australia. Email: keith.mcdougall@environment.nsw.gov.au
Australian Journal of Botany 56(6) 461-468 https://doi.org/10.1071/BT08036
Submitted: 3 March 2008 Accepted: 4 August 2008 Published: 16 September 2008
Abstract
Grasslands in the Riverina region of south-eastern Australia have long been thought to be derived from woodland dominated by Acacia pendula A.Cunn. ex G.Don and Atriplex nummularia Lindl. following over-grazing and clearing in the 19th Century. Despite the broad acceptance of this view, there is little evidence for such a universal change having occurred. Phytosociological and historical evidence is presented here, which suggests that, although many of the existing grassland remnants are floristically similar to remnants of A. pendula woodland and are probably derived from woodland, natural treeless grassland also probably occurs in the Riverina. Such grassland is floristically distinct from remnant woodland and generally spatially separate, being prevalent in the southern Riverina. Although the delineation of natural and derived grassland boundaries may now be difficult, grassland vegetation in general is of immense biodiversity significance, containing a large number of highly localised rare or threatened species. A decrease in rainfall during the winter and spring growing season, as predicted by climate-change models, may be detrimental to natural grassland, which is restricted to the higher rainfall portion of the Riverina.
Acknowledgements
I am grateful to Matt White (Victorian Department of Sustainability and Environment) for provision of electronic data for Victorian quadrat sites, to Megan McNellie for provision of much of the NSW data and to Damon Oliver for comments on an early draft. Ian Lunt greatly helped with transforming the paper into its published form.
Benson JS,
Ashby EM, Porteners MF
(1997) The native grasslands of the Riverine Plain, New South Wales. Cunninghamia 5, 1–48.
Benson JS,
Allen C,
Togher C, Lemmon J
(2006) New South Wales vegetation classification and assessment: Part 1. Plant communities of the NSW Western Plains. Cunninghamia 9, 383–451.
Lunt ID
(1997) The distribution and environmental relationships of native grasslands on the lowland Gippsland Plain, Victoria: an historical study. Australian Geographical Studies 35, 140–152.
| Crossref | GoogleScholarGoogle Scholar |
Moore CWE
(1953) The vegetation of the south-eastern Riverina, New South Wales. I. The climax communities. Australian Journal of Botany 1, 485–547.
| Crossref | GoogleScholarGoogle Scholar |
Morcom LA, Westbrooke ME
(1998) The pre-settlement vegetation of the western and central Wimmera Plains of Victoria, Australia. Australian Geographical Studies 36, 273–288.
| Crossref | GoogleScholarGoogle Scholar |
Porteners MF
(1993) The natural vegetation of the Hay Plain, Booligal-Hay and Deniliquin-Bendigo 1 : 250 000 maps. Cunninghamia 3, 1–122.
Williams OB
(1969) Studies in the ecology of the Riverine Plain. V. Plant density response of species in a Danthonia caespitosa grassland to 16 years of grazing by Merino sheep. Australian Journal of Botany 17, 255–268.
| Crossref |