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The ABS's environmental statistics reporting fails the basic test of rigour

By Jennifer Marohasy - posted Monday, 29 March 2004


No species extinctions have been recorded in Australia over the past two decades. Several species have been rediscovered, including the mahogany glider. If the ABS had chosen to compare the number of known extinctions to the number of rediscoveries or, for example, reported on the increase in area of conservation reserve set aside for biodiversity protection, then the report might have concluded that biodiversity in Australia is actually increasing.

Land Clearance

Land clearance is the second environmental "headline indicator" in the ABS report. The report’s main conclusion is that "Land clearing continues to have a major impact on our biodiversity, soil and water. Since the mid-1990s, the rate of land clearance has increased. Estimates indicate that about 470,000 hectares of land were cleared in 1999, around 90 per cent in Queensland." The ABS, however, does not place the 470,000 hectares in any context relative to the land mass of Australia, the area planted to new forests, and the area of trees naturally thickening and regenerating.

Instead, the ABS report describes the area cleared in terms of numbers of football fields, attributes the clearing to agriculture, and laments the number of birds which it estimates permanently lose their habitat as a consequence of the clearing.

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Interestingly, the 2002 ABS report only presents data up to 1999 for land clearance. The omission of the 1999 to 2001 data has the effect of excluding data which show an approximate 50 per cent reduction in land clearance in Queensland from 1999 to 2001.

The national clearing rate in the ABS report of 470,000 hectares in 1999, while not trivial, actually represents less than 0.2 per cent of the land area of Queensland and less than 0.06 per cent of the land area of Australia. According to Australia’s State of the Forests Report 2003, 638,000 hectares were planted to hardwood in 2002, mostly on land that was once used for agriculture.

It is interesting to compare the ABS conclusion that "40 per cent more land (135,000 hectares) was cleared in 1999 than in 1991" with Australia’s State of the Forests Report 2003 conclusion that 240,000 hectares were cleared in 1998 — a reduction on the area cleared in 1988 of 546,000 hectares. The difference in area cleared between the two reports relates, at least in part, to differences in definitions of "forest" and "vegetation" used by the two different Federal government departments.

The 2003 forest report actually shows an increase of 7 million hectares of forest cover in Australia but suggests that the increase does not represent a real increase in forest cover but rather an improvement in forest mapping. It has been argued that there is actually ambiguity and discrepancy with respect to 31 million hectares of forest cover between the 1998 and 2003 forest reports.

Most of the land clearance reported in the ABS report is associated with cattle grazing in Queensland — an activity occurring over about 50 million hectares of rangeland. Studies indicate that at the time of European settlement many of these rangeland areas were not climax (that is, in a mature state) but rather were a fire-mediated sub-climax developed over 5,000 years of Aboriginal burning. In the absence of fire and with increased grazing pressure, there has been a general and rapid vegetation thickening, resulting in many more trees per hectare now than there were 150 years ago.

Worldwide, vegetation thickening is an issue in rangelands with potentially significantly impacts on biodiversity, carbon and water balances. Queensland satellite data show that 26 per cent of all clearing in 2000–2001 was of land that had no trees in 1991. In Texas (USA), landholders are encouraged to clear trees to improve water supplies.

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Land clearance can potentially increase biodiversity in a situation where vegetation thickening threatens native grasslands. Indeed, grassland animals have evolved with adaptations (pdf, 1.4MB) including reaction times and escape speeds suited to a treeless environment. The shorter spacing between trees in woodlands and thickening woodland can make them easy prey. When all this is considered, linking an increase in land clearance with a decrease in biodiversity is highly misleading.

In conclusion

The ABS purports to "assist and encourage informed decision-making, research and discussion within governments and the community, by providing a high quality, objective and responsive national statistical service".

The first two "headline indicators" in its much-quoted Measuring Australia’s Progress report are concerned with biodiversity. An increase in the numbers of species listed under the EPBC Act, and an apparent increase in land-clearance rates in Queensland, are purported to indicate that Australia’s biodiversity is in decline. However, the analysis lacks rigour and objectivity.

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This article was first published in The IPA Review on 15 December 2003.



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About the Author

Jennifer Marohasy is a senior fellow with the Institute for Public Affairs.

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