Australian Natural Resources Atlas

Natural Resource Topics

Rangelands - Overview

Location map of Riverina bioregion

Riverina

Summary

ATSIC BoundariesCatchment BasinsStatistical Local Areas

Introduction

The Riverina bioregion covers 95,900 sq. kms of grazing and agricultural land in New South Wales and Victoria. Approximately 25% of this bioregion is on the Victorian side of the border and 75% lies within New South Wales. Most of the rangeland grazing areas are in New South Wales so the information provided here is in relation to this state only. In New South Wales, the Riverina bioregion extends from the Murray River in the south to Mossgiel and Roto in the north. The eastern boundary includes the city of Griffith and includes a narrow strip of country along the Murray River through to South Australia. It includes other major towns such as Hay, Jerildrie, Hillston, Deniliquin and Coleambally

Natural Environment

Climate

The Riverina bioregion is semi-arid with low rainfall, hot summers and cool winters. The mean annual rainfall decreases from about 400mm in the east near Griffith to 310mm at Balranald in the west. The rainfall is slightly winter dominant but there are high intensity thunderstorms in summer that are of short duration, unreliable and local in their influence. Most pasture growth takes place between May and October because winter rainfall is the most reliable. Droughts are common with rainfall variability being greatest in the north and west of the bioregion.

The hottest month is January and the coldest month is July. The average daily temperature at Hay in January is 17.2? C - 33.0? C and for July it is 3.6? C - 14.8? C. The average daily temperature for January is about two degrees higher in the north than the south. The highest evaporation rates are in the west and occur between November and February.

For further details on climate averages in this region refer to the Bureau of Meteorology site: http://www.bom.gov.au/climate/map/climate_avgs/a75.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 Riverina bioregion for this year and previous years can be found at: http://www.environment.gov.au/erin/ndvi/ttrace/riv.html.

 

Landforms and hydrology

This bioregion consists of a plain with low relief. It slopes gradually to the west with an elevation of 150m along its eastern edge down to 60m at Balranald in the west. There are some rocky ranges but they are not extensive and only rise to around 250m. The bioregion is essentially a riverine floodplain created by ancestral rivers and streams and now dissected by present-day creek and river systems. Major river systems are a feature of this bioregion. The Murray River crosses the full width of the bioregion and forms the border between New South Wales and Victoria. The Lachlan River runs down much of the western boundary and the Murrumbidgee River system and other tributaries of the Murray River lie within this bioregion. Some aeolian features occur on the alluvial plains and these have formed dunes and lunettes around dry lake-beds.

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/.

For further details on wetlands within the bioregion refer to:

www.biodiversity.environment.gov.au/environm/wetlands/directory/wetdir.htm.

Soils

The bioregion is characterised by four main soil types:

Red-brown earths are the dominant soil type in the eastern part of Riverine Plain between Hay, Deniliquin and Griffith. These are moderately fertile but with a hard-setting topsoil that is prone to structural breakdown.

Grey, brown and red clays are common on the Riverine Plain in the Mossgiel - Hay - Moulamein area and along the floodplains of the main river and creek systems. These are deep soils that are less subject to erosion.

Red earths occur in the north east of the bioregion. They have weakly developed horizons with very little organic matter and moderately susceptible to windsheeting and gullying but the hardsetting surface crust gives some protection against erosion. There is extensive dryland cropping on these soils.

Solonised brown soils occupy an extensive area in the west. They contain large amounts of calcareous material in the profile. They are susceptible to windsheeting and drift that can result in limestone scalds.

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

Vegetation

There are five major vegetation associations in the Riverina bioregion: grey-box, river red gum, black box, bimble box and white cypress pine complex; mallee and belah/rosewood woodland communities; bladder saltbush and black bluebush shrublands; native grasslands; and wetlands.These are described below.

The generally treeless plains communities of bladder saltbush and black bluebush, and native grasslands dominate and provide the characterisation of the bioregion.

Eucalypt and Pine woodlands

Grey box (Eucalyptus microcarpa) dominated communities occur on the level to undulating country on the red-brown earths. The groundcover generally consists of perennial grasses such as whitetop (Danthonia caespitosa), together with annual and perennial forbs.

River red gum (E. camaldulensis) communities occur along the rivers and creeks and where the watertable is high enough to saturate the root zone. A variety of groundcover occurs including grasses, sedges and forms as well as low shrubs such as ruby saltbush (Enchylaena tomentosa).

Black box (E. la.giflorens) communities are found on the grey clay soils associated with watercourses and depressions that are experience less inundation than those with river red gum.

Bimble box (E. populnea) and white cypress pine (Callitris glaucophylla) communities are found on the red earths and red-brown earths particularly in the north east of the bioregion.

Mallee and Belah-Rosewood

Mallee (E. dumosa & E.socialis) species are found in the bioregion. Those dominated by E. dumosa occur in the north-east and south-west of the bioregion. Green mallee (E. viridis) communities occur on the low ridges in the north east of the bioregion on skeletal or shallow gravelly soils. Mallee often occurs as a continuous stand but it may contain other species such as ironbark.

Belah/rosewood (Casuarina cristata, Alectron leifolium) communities are found on solonise d brown soils in general, but can be found occurring in most soil types. Other species found include a variety of acacias & sennas as well as wilga (Geijera spp.) and cypress pine (Callitris spp.). Shrubs associated with these communities include thorny and ruby saltbushes (Rhagodia spp.).

Saltbush and Bluebush

Bladder saltbush (Atriplex vesicaria) occurs on the grey and brown clays and shallow surfaced red-brown earths in the western part of the bioregion. They are mainly treeless although scattered trees such as black box may be present.

Black bluebush (Maireana pyramidata) occur on brown and red clays in the western parts of the bioregion. Other shrubs present include pearl bluebush (M.sedifolia), satiny bluebush (M.georgii) and dillon bush as well as a variety of perennial and annual forbs and grasses (such as Stipa spp, Sclerolaena spp, Medicago spp and Plantain spp).

Native Grasslands

Native grasslands can be dominated by the perennial wallaby grass (Danthonia caespitosa). These communities occur on the clay soils and loamy red earths throughout the bioregion. They contain other grass species and are mainly treeless except for scattered individual trees. Annual species of grass can be abundant in winter and spring. Many grasslands are now considered to be disclimax shrublands or boree or myall(Acacia pendula) woodlands.

Wetlands

There are significant wetlands throughout the bioregion as well as other areas subject to periodic flooding that contain similar vegetation. Lignum (Muehlenbeckia florulenta) is the most common species associated with these sites. Canegrass communities occur on lakebeds with compact clay soils. Reed and rush communities occur throughout the bioregion on sites that are more or less permanently inundated.

Fauna

The Riverina bioregion contains a rich and diverse fauna. There are a variety of habitats due to the combination of grasslands, shrublands woodlands and wetlands in close proximity in a relatively fertile region. Many of these habitats remain but the area was highly desirable for agriculture and the changed circumstances that have occurred means that many of the original fauna can no longer be found in the bioregion.

There are 12 species of plants and 46 species of birds and mammals are listed as threatened species in this bioregion. The plains-wanderer (Pedionomus torquatus) is an example of one of the threatened fauna species. It was once widespread but now has its core distribution within the bioregion. The National Parks and Wildlife Service are preparing a Recovery Plan for this species. Many individual fish species and total fish populations have also diminished because of the physical changes to the river system such as weirs and irrigation diversion of water and water quality through impacts such as salinity.

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

Most of this bioregion is freehold land. However, part of it extends into the Western Division of New South Wales, which is held as leasehold.

There are also a number of nature reserves in the region, including Willandra National Park, Goonawarra Nature Reserve, Lake Urana Nature Reserve and Yanga Nature Reserve.

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

Agriculture is the main economic activity in this bioregion and it is one of the most productive in Australia. The total value of agricultural production in the bioregion was approximately $1.3 billion( Rochelle I could not check this figure- it may need substantiation?) in 1996, which represented 18% of total agricultural production for all of New South Wales. The reason for this high agricultural production lies in a combination of availability of water for irrigation and extensive areas of relatively fertile soils. This provides a base for a diverse range of enterprises.

Nearly all of Australia's rice is grown in this bioregion alone. Irrigation also provides for a major horticultural industry that includes wine grapes, vegetables and citrus.

Wheat and other broadacre crops such as sorghum, maize and soybeans are major enterprises. Underlying these are the grazing industries, which apart from the usual sheep and cattle enterprises includes dairy farming. Many of the well-known merino sheep studs of southern NSW occur in this bioregion. The availability of locally produced grain has also attracted intensive pig, beef feedlotting and poultry enterprises. While the majority of the land area of this bioregion is used for extensive pastoralism the high production areas of irrigation development generate the major income for the area.

Condition Of the Landscape

Land degradation

The major cause of land degradation in the area is through over-grazing; while river water quality decline and increased salinity have resulted from the extensive development of irrigation districts within the bioregion. Extensive clearing of native vegetation has also occurred. This does not only involve tree clearing but also includes shrublands and grasslands. The Western Riverina Vegetation Management Plan has made significant progress in addressing native vegetation management.

The flat topography of the riverine plain with its deeper soils means that much of the area is protected from severe soil erosion caused by runoff. Some water erosion does occur in the eastern parts of the bioregion. Soil structure decline is a problem on the extensive dryland cropping areas and these require appropriate management.

Pest species

The main introduced pest animals are the rabbit, cat, pig and fox. It is widely believed that the cat and fox have had, and continue to have, a significant impact on birds and small to medium sized mammals.

A number of introduced weeds such as bathurst burr (Xanthium spinosum), capeweed (Arctotheca calendula), patterson's curse (Echium plantagineum) and spear thistle (Cirsium vulgare), are a problem in the bioregion. Two of these introduced species, tobacco bush (Nicotiana glauca) and african boxthorn (Lycium ferocissimum), have become established as woody weeds. Infestations of native woody weed species are also affecting some of the more arid parts of the bioregion such as around Hillston.

Social & Economic Aspects

People

There are seven known Aboriginal language groups in this bioregion, although there is still debate about the extent of land each might have occupied and the existence of other groups and how they may have interacted. The seven groups are the Ngiyampaa, Wiradjuri, Yota Yota, Nari-Nari, Baraba-Baraba, Wamba-Wamba and Wadi-Wadi.

The bioregion is within the ATSIC regions of Tamworth, Wagga Wagga, Bourke and Roma and are managed by their respective regional councils, Kamilaroi, Binaal Billa, Murdi Paaki and Goolburri (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.

The Aboriginal mounds on the Hay Plain that was occupied by the Nari Nari are unique on an international scale. They were only recently found by Europeans and indicate that there are many other significant Aboriginal sites yet to be recognised. The Western Riverina Regional Vegetation Committee will develop a Regional Vegetation Management Plan for the greater part of this bioregion.

The multicultural aspects of the irrigation area communities have had a major influence on the social and cultural development of the bioregion.

Land and Water Management Plans under the Department of Land and Water Conservation (DLWC) have been developed for a number of the Irrigation Districts in the bioregion. DLWC also provide support to rangelands enterprises from offices at Hay and Buronga. Up until the late 1980s CSIRO carried out significant rangelands research from their Deniliquin research facility. The bioregion covers the local government Shires of Balranald, Central Darling, Hay, Wakool, Windouran, Murray, Deniliquin, Conargo, Berrigan, Jerilderie, and parts of Leeton, Griffith and Carrathool Shires. The Sturt Highway crosses the New South Wales portion of this bioregion entering near Griffith in the east and leaving it near Balranald in the west. The Sturt Highway is joined by the Mid Western Highway at Hay. The Riverina Highway runs north to south across the middle of the bioregion and joins the Murray Valley Way just across the Victorian border.

Resources, References & Contacts

Publications

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/a75.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

Environment Australia, Wetland sites:

www.biodiversity.environment.gov.au/environm/wetlands/directory/wetdir.htm

Mineral Resources New South Wales:

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 Parks 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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