1.1.7.1 Ecological systems


The Cooper subregion includes considerable ecological spatial variability as a consequence of its large area (130,000 km2) which includes important interactions between the following environmental factors:

  • a variety of surface geological features and associated soil types, including low ranges and breakaways, cracking clay plains, gibber plains, desert dune fields and alluvial floodplains
  • a gradient in amount and seasonality of rainfall from the north-east corner, where rainfall is somewhat summer-dominated, to the south-west corner, where rainfall is weakly winter-dominated
  • the strong influences of surface water redistribution after rain, even in landscapes with modest degrees of topographic relief, and of access to near-surface groundwater, as is typical of Australian arid and semi-arid landscapes (e.g. Stafford Smith and Morton, 1990).

As an indication of the variability within the Cooper subregion, 14 IBRA subregions (Figure 34; SEWPac, Dataset 1; Bioregional Assessment Programme, Dataset 2) and 27 major vegetation subgroups defined in the NVIS v4.1 classification (Figure 34, Table 10; Australian Government Department of the Environment, Dataset 3) are represented. The north-eastern half of the subregion, where mean annual rainfall is in the range 300 to 600 mm, is dominated by Mitchell grass (Astrebla) tussock grasslands and Mulga open woodlands and sparse shrublands. The south-western half, where rainfall is less than 300 mm, is dominated by Hummock grasslands and saltbush and/or bluebush shrublands, including the sparse forms occurring on gibber plains.

Wetlands listed in DIWA (Department of the Environment, 2014c; Australian Government Department of the Environment, Dataset 9) occupy 12.8% of the area of the subregion and include representation of 21 NVIS v4.1 major vegetation subgroups (Table 10). The Coongie Lakes reserve in the western part of the subregion (Reid and Gillen, 1988; Butcher and Hale, 2011) constitutes a large proportion of the DIWA-listed area. At more than 2 million ha, the Coongie Lakes and their surroundings constitute Australia’s largest area designated as a wetland of international importance under the Ramsar Convention. A smaller Ramsar wetland, Lake Pinaroo, lies immediately south of the subregion, in NSW. Nationally mapped riverine floodplains that are also potentially water dependent, at least in part on a seasonal or multi-year basis through flooding and/or elevated watertable, occupy 12.2% and also include 21 of the vegetation subgroups found within the Cooper subregion (Table 10 and Figure 36). For both the DIWA wetlands and the riverine floodplains, the mapped areas include areas of vegetation subgroups that have low likelihood of being dependent on water in excess of local incident rainfall and sourced from subterranean and/or surface water flows (hereafter termed water dependent as per Methodology for bioregional assessments of the impacts of coal seam gas and coal mining development on water resources (BA methodology; Barrett et al., 2013)). The inclusion of non-water-dependent ecosystems in DIWA wetlands and riverine floodplains is due to the coarse resolution of existing map polygons which include some areas that are sufficiently distant from water bodies and/or sit well above ecologically accessible groundwater. The remaining 84.2% of the area is of terrestrial vegetation subgroups with limited likelihood of being water dependent.

Land use includes 12 of the 37 Australian Land Use and Management (ALUM) classification scheme secondary classes, but their occurrence is highly non-uniform (see Figure 9). Pastoral cattle grazing of native and semi-natural pasture, almost exclusively on leasehold lands (Figure 37), is by far the greatest land use (81.3% of the area), which is consistent with the predominance of semi-arid and arid climates, landscapes and vegetation community types. Conservation is the principal land use for 8.6% of the area, which is equal to the national average of 8.6% in the Australian National Reserve System (excluding lands of private and Indigenous landholders who have conservation amongst multiple land use objectives), above the Queensland average of 7.5% (Department of the Environment, 2012), and below the SA average of 13.7% (excluding regional reserves and Indigenous Protected Areas; 29.8% including these two categories) (Department of the Environment, 2012).

Figure 34

Figure 34 Interim Biogeographic Regionalisation for Australia subregions within the Cooper subregion

Data: SEWPaC (Dataset 1); Bioregional Assessment Programme (Dataset 2)

Figure 35

Figure 35 National Vegetation Information System major vegetation subgroups for the Cooper subregion

Data: Australian Government Department of the Environment (Dataset 3)

Table 10 National Vegetation Information System (v4.1) major vegetation subgroups in the Cooper subregion


Vegetation subgroups (in descending order of area)

Area of subgroup in subregion

(ha)

Area of subgroup in subregion, as percentage of total area of subgroups

(%)

Area of DIWA wetlands in the subgroup

(ha)

Area of DIWA wetlands in the subgroup, as percentage of total area of subgroups

(%)

Area of watercourses and floodplains in subgroup (ha)

Area of watercourses and floodplains in subgroup, as percentage of total area of subgroups (%)

Saltbush and/or bluebush shrublands

2,895,096

22.27%

1,064,180

64.16%

286,785

18.05%

Mitchell grass (Astrebla) tussock grasslands

2,002,662

15.41%

45,703

2.76%

4,528

0.28%

Hummock grasslands

1,474,259

11.34%

2,650

0.16%

4,522

0.28%

Mulga (Acacia aneura) open woodlands and sparse shrublands +/– tussock grass

1,381,198

10.63%

9,585

0.58%

10,952

0.69%

Wet tussock grassland with herbs, sedges or rushes, herblands or ferns

1,137,495

8.75%

116,449

7.02%

580,947

36.56%

Other tussock grasslands

589,746

4.54%

75,173

4.53%

192,393

12.11%

Acacia (+/– low) open woodlands and sparse shrublands +/– tussock grass

578,449

4.45%

84

0.01%

583

0.04%

Other grasslands

562,621

4.33%

27,524

1.66%

172,415

10.85%

Eucalyptus low open woodlands with tussock grass

451,653

3.47%

37

0.00%

5,043

0.32%

Mixed chenopod, samphire +/– forbs

345,079

2.65%

21,343

1.29%

26,014

1.64%

Other Acacia tall open shrublands and shrublands

254,801

1.96%

11,567

0.70%

1,194

0.08%

Other Acacia forests and woodlands

239,818

1.84%

0

0.00%

4,914

0.31%

Lignum shrublands and wetlands

233,256

1.79%

111,559

6.73%

219236

13.80%

Acacia (+/– low) open woodlands and sparse shrublands with hummock grass

178,675

1.37%

2,263

0.14%

453

0.03%

Freshwater, dams, lakes, lagoons or aquatic plants

133,003

1.02%

62,975

3.80%

5,138

0.32%

Eucalyptus open woodlands with a grassy understorey

81,374

0.63%

280

0.02%

26,213

1.65%

Acacia (+/– low) open woodlands and sparse shrublands with chenopods

78,322

0.60%

0

0.00%

1

<0.01%

Acacia (+/– low) open woodlands and sparse shrublands with a shrubby understorey

65,586

0.50%

0

0.00%

1

<0.01%

Eucalyptus woodlands with a shrubby understorey

64,726

0.50%

28,867

1.74%

12,994

0.82%

Cleared, non-native vegetation, buildings

61,652

0.47%

0

0.00%

319

0.02%

Salt lakes and lagoons

41,465

0.32%

31,142

1.88%

5,190

0.33%

Mulga (Acacia aneura) woodlands and shrublands +/- tussock grass +/– forbs

37,025

0.28%

0

0.00%

1,042

0.07%

Eucalyptus (+/– low) open woodlands with a chenopod or samphire understorey

36,358

0.28%

36,358

2.19%

23,880

1.50%

Eucalyptus open woodlands with shrubby understorey

21,376

0.16%

4,669

0.28%

2,415

0.15%

Other open woodlands

11,006

0.08%

0

0.00%

0

0.00%

Mallee with hummock grass

10,269

0.08%

0

0.00%

0

0.00%

Eucalyptus woodlands with a tussock grass understorey

10,084

0.08%

0

0.00%

2

<0.01%

Eucalyptus low open woodlands with a shrubby understorey

8,667

0.07%

2,079

0.13%

1,518

0.10%

Unknown/No data

4,528

0.03%

450

0.03%

438

0.03%

Naturally bare, sand, rock, claypan, mudflat

3,786

0.03%

3,766

0.23%

36

<0.01%

Eucalyptus low open woodlands with hummock grass

2,458

0.02%

0

0.00%

0

0.00%

Mulga (Acacia aneura) woodlands and shrublands with hummock grass

1,583

0.01%

0

0.00%

0

0.00%

Brigalow (Acacia harpophylla) forests and woodlands

825

0.01%

0

0.00%

0

0.00%

Sedgelands, rushes or reeds

360

<0.01%

0

0.00%

0

0.00%

Unclassified native vegetation

17

<0.01%

17

<0.01%

17

<0.01%

Total

12,999,278

100.00%

1,658,720

100.00%

1,589,183

100.00%

Data: Australian Government Department of the Environment (Dataset 3, Dataset 9); Geoscience Australia (Dataset 14)

Watercourses and floodplains from the combination of all other datasets listed as sources for Figure 36

Figure 36

Figure 36 Conservation areas (including wetlands listed in A directory of important wetlands in Australia), springs and riverine floodplains with potential for water dependence for the Cooper subregion

Data: Bioregional Assessment Programme (Dataset 4); Queensland Herbarium, Environmental Protection Agency (Dataset 5); Australian Government Department of the Environment (Dataset 3); Geoscience Australia (Dataset 6, Dataset 7, Dataset 8); Australian Government Department of the Environment (Dataset 9, Dataset 10)

Table 11 Australian Land Use and Management Classification (version 7) land use classes in the Cooper subregion


ALUM secondary land use class

Area in subregion

(ha)

Area in subregion, as percentage of total

(%)

Grazing natural vegetation

10,568,872

81.30%

Nature conservation

1,113,135

8.56%

Mining

814,609

6.27%

Marsh/wetland

401,843

3.09%

Lake

96,063

0.74%

River

2,298

0.02%

Utilities

1,500

0.01%

Transport and communication

346

<0.01%

Reservoir/dam

160

<0.01%

Services

179

<0.01%

Residential and farm infrastructure

178

<0.01%

Manufacturing and industrial

95

<0.01%

Total

12,999,278

Data: ABARE-BRS (Dataset 15)

Figure 37

Figure 37 Land tenure as at 2009 for the Cooper subregion

Data: Geoscience Australia (Dataset 11, Dataset 12, Dataset 13)

Last updated:
5 January 2018
Thumbnail of the Cooper subregion

Product Finalisation date

2015

ASSESSMENT