Australian Natural Resources Atlas

Natural Resource Topics

Rangelands - Overview

Location map of Cobar Peneplain bioregion

Cobar Peneplain

Summary

ATSIC Boundaries Catchment Basins Statistical Local Areas

Introduction

The Cobar Peneplain occupies an area of 73,500 sq. kms within the state of New South Wales and represents 9% of the State. It spans central and far-western New South Wales and extends almost to Bourke in the north to Griffith in the south. It is bounded by the Darling and Bogan Rivers in the north-west and north-east respectively. The section of this bioregion lying south of the Lachlan River has been developed for cropping, as has the eastern margin of the bioregion.

Natural Environment

Climate

The Cobar Peneplain Bioregion is a semi-arid area with rainfall ranging from 260mm in the north-west to about 500mm in the south-east. Rainfall is highly variable over the whole region and prolonged periods of low rainfall with intermittent floods are characteristic (Pickard & Norris, 1994). Rainfall is summer-dominant in the north of the region and winter-dominant in the south. November to March is the hottest period, with frequent maximum daily temperatures in excess of 38? C. The coldest month is July and frequent frosts occur between June and August.

The town of Cobar is situated close to the centre of this bioregion. It has a mean annual rainfall of approximately 353mm. The daily mean maximum temperature ranges between 15.5 C and 34 C.

Climate averages are available for Cobar and Nyngan:

http://www.bom.gov.au/climate/map/climate_avgs/a53.shtml.

For monthly rainfall and temperature graphs refer to Bureau of Meteorology website: www.bom.gov.au/climate/forms/map_forms/new_imagemaps/nsw_name.html.

Current seasonal conditions and their historical context can be provided by satellite imagery. The Normalised Difference Vegetation Index (NDVI) is a measure of the vegetation 'greenness'. The NDVI for the Cobar Peneplains bioregion for this year and previous years can be found at: http://www.environment.gov.au/erin/ndvi/ttrace/cp.html.

Landforms and hydrology

The Cobar Peneplain is part of the Lachlan Fold Belt, which predominantly consists of folded and faulted Palaeozoic rocks (251-545 million years ago). The region is dominated by undulating low rounded to steep ridges, rolling downs and plains.

The north and east borders of the bioregion are bound by the alluvial plains of the Darling and Bogan Rivers, which comprise the Darling Riverine Plains bioregion. The western boundary is identified by the sandy dunes and plains of the Murray Darling Depression bioregion. The indistinct south-eastern boundary is formed with the New South Wales South-western Slopes bioregion of the Eastern Highlands.

The Lachlan River flows through the southern portion of the bioregion. A northwest trending watershed from Louth to Condobolin drains streams to the north and west into the Darling and Lachlan River systems, although many of the creeks spread out over plain areas and rarely reach the river systems.

For more detailed geological information and map refer to the Australian Geological Survey Organisation website: www.agso.gov.au/map/ and the Mineral Resources New South Wales: www.minerals.nsw.gov.au/.

Soils

The bioregion contains a wide range of soil types. Sands, sandy earths and red earth soils are dominant in the upland areas. The footslopes and lower areas are predominantly colluvial and aeolian (wind deposited) sediments with alluvial sediments associated along streams.

For further information on soils refer to the Murray-Darling Basin Soil Information at: www.brs.gov.au/mdbsis

Vegetation

The Cobar Peneplain has a number of distinct vegetation communities.

The northern areas of the region (south of the Darling River) are characterised by open woodlands and woodlands of bimble box (Eucalyptus populnea). The more arid bimble box / red box (Eucalyptus intertexta) woodlands form communities with mulga (Acacia aneura).

The arid north-western parts of the region are dominated extensively by mulga communities, interspersed with bimble box along the lowlands. Horse mulga (Acacia ramulosa) and belah-rosewood (Casuarina pauper - Alectryon oleifolius) communities occur along the north western bioregional boundary.

The ridges and low rises in the central-south eastern parts of the region are characterised by white cypress pine (Callitris glaucophylla) communities, often in conjunction with red box on the rises and bimble box on the flats. The white cypress pine often develops into dense stands of 'whipstick' regrowth. Mallee communities occupy many of the rocky hills and ridges throughout the region.

South of the Lachlan River, the vegetation communities are comparatively complex when compared to those of the northern parts. The south is typically dominated by grey box (Eucalyptus microcarpa), which blends with white box (Eucalyptus conica) towards the east. Mugga ironbark (Eucalyptus sideroxylon) occurs on the stony ridge-tops.

Fauna

The diversity of habitat provided by the landscape and vegetation of the region supports a wide variety of fauna species. Of the 658 vertebrate fauna species identified in the Western Zone of New South Wales, some 405 have been recorded within the Cobar Peneplain.

There are 36 vulnerable and seven endangered fauna species within the bioregion. An additional 64 birds; 12 mammals; 23 reptiles and eight frogs are of conservation concern because they are declining, or locally extinct within the bioregion are identified.

Birds that are dependent on woodlands are threatened throughout this bioregion because of land clearing, habitat change such as woody weed invasion and grazing. The major mitchell's cockatoo (Cacatua leadbeateri), the turquoise parrot (Neophema pulchella), and the painted honeyeater (Grantiella picta) are significantly threatened by the loss of bimble box and white cypress pine (Callitris glaucophylla) woodlands.

Other species of threatened birds are the striated grasswren (Amytornis striatus), the shy heathwren (Hylacola cauta), the pied honeyeater (Grantiella picta), the southern scrub-robin (Drymodes brunneopygia), the red-lored whistler (Pachycephala rufogularis), gilbert's whistler (Pachycephala inornata), the masked owl (Tyto novaehollandiae), the swift parrot (Lathamus discolor) and the superb parrot (Polytelis swainsonii).

The kultarr (Antechinomys laniger) has declined markedly in this bioregion. Other species that have declined are the koala (Phascolarctos cinereus), the southern bell frog (Litoria raniformis), the narrow-banded snake (Simoselaps fasciolatus), the stripe-faced dunnart (Sminthopsis macroura), the brush-tailed rock-wallaby (Petrogale penicillata), and the greater long-eared bat (Nyctophilus timoriensis).

For more information on threatened species refer to the NSW National Parks and Wildlife Service at: http://www.npws.nsw.gov.au/wildlife/index.html.

Land Tenure & Use

Land tenure

About 60% of the Cobar Peneplain bioregion lies within the Western Division administrative area of New South The remaining 40% lies in the Central Division. Lands in the Western Division are predominantly leasehold tenure and those of the Central Division are predominantly freehold.

Twelve areas are reserved as national park or nature reserve within the Cobar Peneplain. The total area of the Cobar Peneplain occupied by these reserves is 118,900 ha. They occupy approximately 2 % of the bioregion. The major nature reserves include, Cocoparra National Park, Gundabooka National Park, Round Hill Nature Reserve, Woggoon Nature Reserve, Yathong Nature Reserve and a number of small nature reserves.

Further information on conservation reserve is available at the NSW National Parks and Wildlife Service website: http://www.npws.nsw.gov.au/parks/index.html.

Land use

The primary land use in the rangelands portion of this bioregion is sheep grazing (Woinarski, et. al., in prep.). The border dingo fence protects the area. Cattle grazing occurs but it not as important as the sheep industry. Dryland cropping also occurs in the rangelands area as new varieties and agronomic techniques move the wheatbelt further west.

Cobar is also an important mining centre in New South Wales. It has been the States largest producer of copper and a notable producer of silver-lead-zinc and gold.

Condition Of the Landscape

Land degradation

Clearing controls on the leasehold Western Division lands has resulted in less clearing of native vegetation on the rangelands portion of this bioregion than has occurred elsewhere in New South Wales. However, a number of applications to clear for cropping are approved and this results in blocks of cleared country referred to as window-pane clearing.

Grazing is extensive, and so whilst many woodland communities have intact over-storey vegetation, their under-storeys may often be non-existent. Soil structure decline and erosion are significant problems in both Divisions, particularly in the north-west, where sheet erosion and gullying are common.

The dominance and spread of unpalatable native species of woody weeds such as budda (Eremophila mitchellii), turpentine (E. sturtii) broad-leaf hop-bush(Dodonaea viscosa) and punty bush (Sennaartemisioides) has occurred over significant areas of the region.

Pest species

Vertebrate pests are an issue of significance for this bioregion. The most notable of these is the feral pig. It is a serious pest of agricultural crops and even livestock such as lambs. It also preys on wildlife and destroys wetland habitats by rooting out vegetation. Feral goats also cause damage but they are now valued as a resource and mustered or trapped for sale which means they do not build up to the numbers that were once common in this bioregion. High populations of kangaroos also contribute to total grazing pressure from time to time and can be difficult to manage in the woodland environment. Rabbits are generally not a problem on the hard ridges of the bioregion.

Social & Economic Aspects

People

The townships of Cobar, Canbelego, Nymagee, Mt Hope, Euabalong West, Lake Cargelligo and Rankin Springs are located within the bioregion's boundaries whilst Louth, Nyngan, Tottenham, Tullamore, Condobolin and Griffith lay along its boundaries. Eight local government areas lie wholly or partly within the Cobar Peneplain. These are Bourke, Bogan, Brewarrina, Bland, Carrathool, Lachlan, Cobar and Narrandera.

The bioregion is within the ATSIC regions of Wagga Wagga and the regional councils of Binaal Billa (McLennan, 1997). www.atsic.org.au/about_atsic/board_regional_councillors/regional_information.htm For more information on the Aboriginal people of this region refer to Horton (1994) and the relevant web sites on the reference list.

Many landcare groups operate within the bioregion. For more information about landcare across the New South Wales western region contact the Department of Land and Water Conservation's Cobar office. The Department of Land and Water Conservation provides technical support to individuals and landcare groups in the areas of vegetation management, groundwater advice, water quality monitoring, riparian management, rangelands management and rehabilitation, catchment management advice and regional landcare support. The regional office for the western region of New South Wales is at Dubbo, and relevant district offices servicing the area are at Condobolin, Bourke, Nyngan and Cobar.

West 2000 is a voluntary partnership program established for landholders in the Western Division by the New South Wales and Commonwealth Governments. It aims to increase the viability and sustainability of the Western Division.

Resources, References & Contacts

Publications

Ayers, D., Nash, S., & Baggett, K. 1996, Threatened Species of Western New South Wales, NSW Soil Conservation Service, Government Printer, Sydney, NSW.

Beadle, N. C. W. 1948, The Vegetation and Pastures of Western New South Wales, with Special Reference to Soil Erosion, NSW Department of Conservation, Hurstville, NSW.

Creaser, P. M. & Knight, A. T. 1996, Bioregional Conservation Strategy for the Cobar Peneplain; Stage I. Unpublished Report, NSW National Parks and Wildlife Service, Hurstville, NSW.

Cunningham G. M., Mulham W. E., Milthorpe P. L. & Leigh J. H. 1981, Plants of Western NSW. Government Printer, Sydney, NSW.

Davis, B. W. & Drake, G. A. 1983, Australia's Biosphere Reserves: Conserving Ecological Diversity, Australian National Commission for UNESCO, Australian Government Printing Service, Canberra, ACT.

Irons, N.M. and Quinlan, E. E. 1988, A Review of Information Relevant to the Mulga Rangelands of Western N.S.W., Technical Report No 5 Soil Conservation Service of N.S.W.

Iwaszkiewicz, A. and Semple, W.S. 1988, A Review of Information Relevant to the Bimble Box-Pine and Associated Rangelands of Western N.S.W., Technical Report No 6 Soil Conservation Service of N.S.W.

Morgan, G. & Terrey, J. 1992, Nature Conservation in Western NSW, National Parks Association of NSW, Sydney, NSW.

Noble, J. and Tongway, D. 1986, 'Pastoral Settlement in Arid and Semi-Arid Rangelands' in Australian Soils - the Human Impact, eds. J. S. Russell and R. F. Isbell, University of Queensland Press in association with the Australian Society of Social Science, St. Lucia, Queensland.

Smart, J. M., Knight, A. T. & Robinson, M. 2000, A Conservation Assessment for the Cobar Peneplain Biogeographic Region - Methods and Opportunities, NSW National Parks and Wildlife Service Report, Hurstville, NSW

Horton, D. R. 1994, The Encyclopaedia of Aboriginal Australia, Aboriginal Studies Press for the Australian Institute of Aboriginal and Torres Strait Islander Studies, Canberra, ACT.

McLennan. W. 1997, 1994 National Aboriginal and Torres Strait Islander Survey: Social Atlas, Australian Bureau of Statistics, Canberra, ACT.

Mazzer, T., Ellis, M., Smith, J., Cooper, M., Wallace, G., Langdon, A., 1988, 'Fauna of western NSW - the Southern Mallee Region,' National Parks and Wildlife Service NSW, Sydney, NSW.

Morton, S. R., Short, J. & Barker, R. D., with an appendix by G. F. Griffin & G. Pearce 1995, Refugia for Biological Diversity in Arid and Semi-arid Australia, a report to the Biodiversity Unit of the Department of Environment, Sport and Territories, Biodiversity Series, Paper no. 4, Dept. of the Environment, Sport and Territories, Canberra, ACT.

New South Wales National Parks and Wildlife Service, Western Directorate. Unpublished report on Murray Darling Depression Bioregion.

Parkes, J., Henzell, R. & Pickles, G. 1996, Managing Vertebrate Pests: Feral Goats, Australian Government Publishing Service, Canberra, ACT.

Pickard J. and Norris E.H. 1994, The Natural Vegetation of North-Western New South Wales. Notes to accompany the 1:1 000 000 vegetation map sheet. Cunninghamia 3(3), 423-464.

Robson, A.D. 1994, The Case for Multiple Use Reserves in Woody Weed Country. Working papers; 8th Biennial Conference of the Australian Rangeland Society, 21-23 June 1994, Katherine, Northern Territory.

Thackway R. and Cresswell I.D. (Eds) 1995: An Interim Biogeographic Regionalisation for Australia: A framework for setting priorities in the National Reserves System Cooperative Program, Version 4.0. Australian Nature Conservation Agency, Canberra.

Saunders, G., Coman, B., Kinnear, J. & Braysher, M. 1995, Managing Vertebrate Pests: Foxes, Australian Government Publishing Service, Canberra, ACT.

Walker, P.J. (comp.) 1991, Land Systems of New South Wales: Technical Report No. 25, Soil Conservation Service of NSW.

Williams, K., Parer, I., Coman, B., Burley, J. & Braysher, M. 1995, Managing Vertebrate Pests: Rabbits, Bureau of Resource Sciences and CSIRO Division of Wildlife and Ecology, Australian Government Publishing Service, Canberra, ACT.

Woinarski J., Fensham, R., Whitehead, P. & Fisher, A., with map production by Verhagen, C. in preparation, Biodiversity in the Australian Rangelands: a Review of Changes in Status and Threatening Processes. Draft report prepared as a resource document for Project 3: Developing an Adaptive Framework for Monitoring Biodiversity in Australia's Rangelands, of the National Land and Water Resources Audit, Theme 4 (Rangelands monitoring) by the Tropical Savannas Cooperative Research Centre, Darwin, Northern Territory.

Websites and contacts

Aboriginal languages of Australia:

http://www.dnathan.com/VL/

Aboriginal Studies WWW Virtual Library:

http://www.ciolek.com/WWWVL-Aboriginal.html

Australian Landcare Council:

www.dpie.gov.au/agfor/landcare/org/alc.html.au

Aboriginal Torres Strait Islander Commission (ATSIC):

www.atsic.org.au/about_atsic/board_regional_councillors/regional_information.htm

Australian Geological Survey Organisation, Geology of Australia:

www.agso.gov.au/map/

Bureau of Meteorology, Climate averages:

http://www.bom.gov.au/climate/map/climate_avgs/a53.shtml

Bureau of Meteorology, Temperature and rainfall graphs: www.bom.gov.au/climate/forms/map_forms/new_imagemaps/nsw_name.html

Bureau of Rural Sciences, Digital Atlas of Australian Soils:

www.brs.gov.au/data/datasets/atlas/index.html

Environment Australia, Normalized Difference Vegetation Index (NDVI) information including bioregional information:

www.environment.gov.au/erin/ndvi/index.html

Mineral Resources New South Wales:

http://www.minerals.nsw.gov.au/

Murray-Darling Basin Soil Information:

www.brs.gov.au/mdbsis

Murray-Darling Basin Commission:

http://www.mdbc.gov.au/

NSW Agriculture:

http://www.agric.nsw.gov.au

NSW Department of Land and Water Conservation:

www.dlwc.nsw.gov.au/

NSW Department of Local Government:

http://www.dlg.nsw.gov.au/

NSW National Parks and Wildlife Service, Wildlife and National Park information:

http://www.npws.nsw.gov.au/parks/index.html

http://www.npws.nsw.gov.au/wildlife/index.html

Plant Information Network System of the Royal Botanic Gardens:

www.plantnet.rbgsyd.gov.au/,

Royal Botanic Gardens:

www.rbgsyd.gov.au/html/science.html

Tourism NSW:

www.tourism.nsw.gov.au/tnsw/

WEST 2000:

www.west2000.org.au

Link to the Map Maker to make a map using this information.

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