An overview of recent native vegetation clearance in Australia and its implications for biodiversity
Biodiversity Series, Paper No. 6
Andreas Glanznig, Biodiversity Unit
Department of the Environment, Sport and Territories, June 1995
Summary of recent native vegetation clearance in Australia
The National Greenhouse Gas Inventory Committee estimated that in 1988 and 1990 some 700 000 ha and 650 000 ha of native vegetation (including regrowth) were cleared for agricultural purposes respectively (NGGIC 1994, p.129b). The magnitude of native vegetation lost during 1990 equates to over one million rugby football fields, or over two rugby football fields being cleared every minute (Cuddon 1980). These estimates have been extrapolated or projected by the Committee to indicate the extent of land cleared between 1983 and 1993. Based on this data, it has been estimated that the total land cleared between 1983 and 1993 for agricultural purposes was over
5 million ha (Buxton 1994, p.98). Table 2 below provides a State/Territories breakdown. The rate and scale of clearance in the years since 1993 may be less than previous years due to drought, lower commodity prices and other economic factors.
|State||Area cleared 1983-93 (ha)||Estimated annual average cleared 1983-93 (ha/yr)||Estimated clearing in 1987-88 (ha/yr)||Estimated clearing in 1989-90 (ha/yr)|
|NSW1||?||150 000||150 000||150 000|
|Qld2||3 000 000||300 000||500 000*||450 000*|
|SA||1983-853a||85 000||11 630||4 471||4 471|
|Tas||1983-884a||36 000||6 000||6 000||6 000*|
|Vic||1983-885a||62 628||7 776||10 438||6 157|
|WA||1983-856a||95 724*||26 028||31 908||31 908|
|NT||1983-918a||162 800||16 280||16 280||16 280|
|National total||some 500 000 ha||some 700 000 ha||some 650 000 ha|
* indicates figures extrapolated from information available for earlier or later in the decade
** recently available data indicates that 100.5 ha were permitted to be cleared and that 696.5 ha were permitted to be cleared with conditions in the period 18 April 1991 to 30 June 1993 (SANVC 1992;1993); see also South Australian section in this paper
Sources of information for estimates of clearing 1983-93:
1. John Benson, Royal Botanic Gardens, Sydney, pers comm
2. Bill Burrows, Tropical Beef Centre, QLDDPI, pers comm
3a. Land clearing permits
3b. Land clearing permits
3c. Land clearing permits
4a. Kirkpatrick (1991)
4b. No data
5a. Woodgate and Black (1988)
5b. Land clearing permits
6a. No data
6b. Kestel Research and VICDCE (1990)
6c. Land clearing permits
7. Rob Corey, ACT Department of Environment, Land and Planning, pers comm
8a. Tim Wheaton, NT Department of Lands, Housing and Local Government, pers comm
8b. Land clearing permits
Source: NGGIC (1994 p.129b)
The data in Table 2 is mostly based on land clearance permits which as mentioned on page 16, provide an indication of intent to clear rather than a direct measurement of vegetation clearance. Consequently, the data may overestimate the amount of vegetation actually cleared.
The estimate includes clearance of native vegetation on previously cleared land. In Queensland, for example, it had been thought that some 400 000 of the approximately 500 000 ha cleared in 1989 was regrowth and 'woody weeds' while the remaining 20 per cent was primarily open eucalypt communities on grazing land (Burrows QLDDPI, cited in NGGIC 1994, p.129a). Recent data, however, suggests that the overall proportion of regrowth and 'woody weeds' cleared may be less than this earlier estimate. For example, the Queensland Department of Environment and Heritage has calculated that in the shires of Bauhinia, Belyando, Emerald, Jericho and Peak Dow, only 379 806 ha or about 45 per cent of the 846 295 ha of tree clearing permits issued since 1990 were for regrowth (QLDDEH 1995a).
Some State estimates, such as for Queensland, are quite uncertain and, as such, the associated errors inherent in the national indicative estimate could be plus or minus 50 per cent (Barson 1995, pers comm); that is the estimated scale of clearing for 1989-90 (some 650 000 ha) could range from 325 000 to 975 000 ha.
The estimate does not include clearance which occurred:
- but was beyond the resolution of remote sensing techniques in instances where the data is based on Landsat imagery, such as for Tasmania (eg. clearance of small patches);
- for houses, buildings and urban infrastructure; and
- for new transport and other corridors or the widening of existing corridors.
The exclusion of data on vegetation clearance for infrastructure development and human settlements masks significant impacts which occurred since the 1970s, particularly in the coastal zone. Over the previous two decades, non-metropolitan coastal towns grew more quickly than cities, with 95 per cent of all population growth taking place in coastal areas in this period (Hamilton and Cocks 1994). Broadscale impacts in the coastal zone are very significant for biodiversity conservation since coastal ecosystems display a high degree of habitat diversity, and compared with other regions the coastal zone is considered to contain the greatest density of threatened species (ANPWS 1992).
The focus of the data on the clearance of forest and woodland communities also masks the loss of grassland ecosystems which have been converted to another use. The loss of lowland temperate grassland communities in particular is very significant for biodiversity conservation. For example, of the estimated around two million ha of lowland grassland in south-eastern Australia at the time of European settlement, the remaining more or less natural remnants add up to perhaps 10 000 ha. That is, an estimated 99.5 per cent of the original grassland vegetation has been destroyed or greatly modified (McDougall and Kirkpatrick 1994, p.158).
Table 2 indicates that in the period of 1983-93 Australia had an estimated average annual clearance rate of some 500 000 ha/year. Comparison between those countries with the highest estimated annual deforestation rates (Table 3) indicates that internationally Australia has a very high average rate of native vegetation clearance in absolute terms. A caveat is that Australia's annual clearance rate includes clearance of regrowth on previously cleared land.
It is also informative to note that during 1990 an estimated some 650 000 ha (NGGIC 1994, p.129b) were cleared in Australia compared to 1.113 million ha (Institute Nacional de Pesquisas Espaciais, 1992) in the Brazilian Amazonia. This indicates that in 1990 the clearance rate for Australia was over half that of the Brazilian Amazonia.
|Country||Annual deforestation rate (000 ha), 1981-90|
|Brazil (Amazonia region)||2 113*|
|Papua New Guinea||113|
* gross figure of deforestation for 1978-88 based on Landsat satellite survey data. Other methods have calculated higher rates of clearance for Brazil. For example FAO sourced data indicates that the annual deforestation rate for the period 1981-90 is about 3.671 million ha (WRI et al 1994, p.307). The rate of clearance in the Brazilian Amazonia appears to be tapering off after a peak in the second half of the 1980s. The amount cleared in 1990/91 was an estimated 1.113 million ha (Institute Nacional de Pesquisas Espaciais 1992).
** estimate provided in the National Greenhouse Gas Inventory for the period 1983-93 (NGGIC 1994, p.129b).
Sources: adapted from Food and Agriculture Organization cited in WRI et al (1994, pp.306-307);
*Institute Nacional De Pesquisas Espaciais (1992);
** National Greenhouse Gas Inventory Committee (1994).