Rangeland reference areas

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Rangeland trend is the change in vegetation present at a particular site over time. Detecting and understanding changes caused by different land uses requires measuring and monitoring those attributes that define how well they are functioning as ecosystems, relative to what is expected from areas largely unaffected by land use (called pristine or reference areas). 

A project to identify, describe and map areas of country in as near to original range condition as possible within the Murchison River catchment area was published in 2004. Its findings are summarised.

Summary of a cooperative project between West Australian Department of Agriculture and Environmental Protection Authority

Resource Management Technical Report 141, 2004. ISSN 0729-3135

Author: David Blood


The rangeland survey program conducted jointly by the Departments of Agriculture (WADA/DAFWA) and Land Administration (DOLA/RDL) since 1970 provides resource information about landforms, soils and vegetation and their condition status in pastoral areas. About 60% of the pastoral areas had been surveyed and mapped by 2004 but final reports had not been published for all areas.

A major use of the survey information is to assist the pastoral industry to develop sustainable grazing management practices. One aspect of sustainable management which DAFWA intends to further promote is the inclusion of areas of rangeland in excellent condition as references for grazing and conservation management in pastoral areas. Small areas of rangelands protected from grazing (such as exclosures and benchmark sites) are important tools in providing reference data for rangeland managers, researchers and administrators. Because of the lack of areas in true reference condition, additional sites are required.

In order to identifty such key areas from existing survey information, a study was initiated. Also WADA/DAFWA wishes to promote the concept of cooperative management of these reference areas with station managers, Land Conservation District Committees (LCDCs) and other key stakeholders.

The concept essentially involves encouraging collaboration between station managers and research and administrative organisations on management of ecologically valuable land and the extension to the industry of possible benefits. The most immediate benefit to pastoral managers is assist them to evaluate the effects of
their management practices on different classes of country.

Reference areas may also have other significant benefits, both to managers and ecologists, for example:

  • protection of genetic resources that may decline under pressure from grazing animals
  • as a source of representative and unmodified natural environments on which to base investigations of arid zone ecological processes
  • provision of future options for multiple land use such as tourism in areas of exceptional natural features or as a destination for educational scientific excursions
  • at a local and practical level, reference areas provide an ideal source of native seed stocks for use in regeneration of degraded land.

Findings and discussion

The table below indicates that poorly accessible land types were less intensively sampled than the survey average, whereas the more accessible washplains were sampled at the same intensity as the survey average. The more productive alluvial river plains were sampled more intensively than average.

Summary of traverse ratings by land type for condition class 0011
Land type Total area (km2) % of total area Total no. of ratings % of total ratings Total 001 ratings % of 001 ratings2 Sampling intensity3
Rough hills 4724 5.5 344 2.5 16 4.6 14
Stony hills and plains 1927 2.2 310 2.3 9 2.9 6
Quartz hills and plains 10 050 11.7 1222 9 16 1.3 8
Breakaways and granitic plains 12 584 14.7 1897 13.9 53 2.8 7
Complex stony and alluvial plains 1722 2.0 294 2.2 9 3.1 6
Permian stony plains 987 1.2 152 1.1 5 3.3 6
Plains of laterite and parent rock 3013 3.5 580 4.3 19 3.3 5
Saline stony plains 471 0.5 118 0.9 2 1.7 4
Spinifex sandplain 67 0.1 21 0.2 5 23.8 3
Bowgada sandplain 9076 10.6 929 6.8 109 11.7 10
Mallee sandplain 290 0.3 17 0.1 2 11.8 17
Sandplain with drainage floors 1087 1.3 143 1.0 4 2.8 8
Hardpan plains and wanderrie banks 6875 8.0 1067 7.8 31 2.9 6
Wash plains on hardpan 23 284 27.2 4220 31.0 78 1.8 6
Calcreted river plains 2091 2.4 535 3.9 27 5.0 4
Alluvial river plains 5689 6.6 1557 11.4 38 2.4 4
Salt lakes with alluvial plains 1649 1.9 185 1.4 33 17.8 9
Clay plains 76 0.1 19 0.1 2 10.5 4
Partly saline lake beds 55 0.1 11 0.1 0 0 5
Totals 85 717 100% 13 621 100% 458 3.4 6.4

1 Condition class 001 = no wind or water erosion, very good vegetation condition.

2 Per cent of 001 ratings per land type = number of 001 ratings/total number of ratings.

3 Sampling intensity = the number of square kilometres per traverse rating.
The table also shows the uneven distribution of 001 traverse ratings. Less pastorally valuable land types such as extensive sandplain have a much higher proportion of 001 ratings than do more productive land types. The very low proportion of 001 ratings on some land types suggests that locating reference areas on these types may be difficult.

Eighty-three potential reference areas were identified. Of these, 42 satisfied the criteria of having three or more sequential 001 ratings, 14 satisfied the criteria of two consecutive 001 ratings and 27 satisfied less rigorous criteria.

On six of the land types, no reference areas satisfying the major criteria of having three or more 001 ratings were found. In some instances this was because of the land types' small size and lack of sampling. But in other cases, it reflected the overall poor condition of the land type. In order to locate some potential reference sites, it was necessary to adopt the lesser criteria as previously described.

Additional information is available from detailed inventory and condition sampling sites adjacent to the possible reference areas as an appendix to the full report

Contact information

Kath Ryan
+61 (0)8 9166 4015


Kath Ryan