Land Theme Report
Australia State of the Environment Report 2001 (Theme Report)
Prepared by: Ann Hamblin, Bureau of Rural Sciences, Authors
Published by CSIRO on behalf of the Department of the Environment and Heritage, 2001
ISBN 0 643 06748 5
Introduction of novel biota into native habitats and communities
Environmental indicators reported on in this section as originally listed and defined in Hamblin (1998):
| Environmental indicator | |
|---|---|
| L4.1A | Number of reports of all, and of new, weeds, pests and diseases per AER and IBRA region |
| L4.1B | Number of passenger and cargo entries per port or entry location by IBRA region |
| L4.2 | a | b | | Impact of agriculture on conservation land by AER and State/Territory |
| L4.5 | Effectiveness of reduction in damage caused by weeds, pests and diseases that are harmful at ecosystem scale by IBRA regions |
Biota may be conveniently classified as:
- endemic (having originated within the regions now found),
- exotic (having originated in a very different region, with a different suite of associated organisms), or
- naturalised (having been exotic, but having established a viable population in the introduced habitat, often with alteration to the biology, morphology or behaviour of the organism).
Australia's long isolation assisted in the development of a high degree of endemism, but has made many species and whole ecotones vulnerable to invasion by exotics. As a consequence of Australia's 19th and early 20th century experience of exotic invasions, we have recently established very highly regulated and stringent quarantine services (National Plant Board 1999). However, even with the advantage of being an island continent, new species continue to enter the continent by many routes. These include:
- blown in by air (e.g. fungal spores, insects), particularly in northern Australia from the Indonesian archipelago,
- in or on ships and aeroplanes,
- on imported goods, and in postal items,
- with people, either legally or illegally, and
- accidentally as contaminants to another legal entry.
Once on the continent, many species may remain undetected until conditions arise that favour rapid proliferation.
Pressure
Number of new weeds, pests and diseases reported per region [L Indicator 4.1A]
The Australian Quarantine Inspection Service (AQIS) and Agriculture, Fisheries and Forestry Australia (AFFA) provide information on the number of new weeds, pests and diseases entering Australia. The National Offices of Animal and Plant Health collate the response to each entry. Their data have been used in compiling this section. Resources are not sufficient to police and prevent all potential exotics entering and spreading in Australia. The greatest effort is spent on controlling species that are potentially damaging to primary industries. This inevitably means that many organisms that may be threatening to native biota are not detected or tracked down as vigorously as those that are known to be a threat to domesticated crop and animal species. In addition, garden plants 'escape' and can carry their own suite of pests and diseases with them as they spread.
The following section concentrates on threats to vegetation, but equally there are threats to native fauna. The greatest threats to native fauna however, already exist in Australia, in the form of loss of habitat through vegetation destruction and introduced predators. These issues are dealt with in detail in the Biodiversity Theme Report.
In the past 25 years several thousand records of detections have been reported, either at quarantine barriers or already in the country, and needing control. A smaller number of unknown species are later found to have been previously unidentified natives, and a very few are initially wrongly identified or are still being identified, classified as false, or pending classification. Figure 42 summarises the total number of reports of all types. While the overall rise over time is concerning, some of this results from better detection and reporting, as well as more traffic that is causing greater pressure on the system.
Figure 42: Total reports of plant-related incursions, 1970-2000.
Source: Plant Health Australia (2001)
To give some sense of proportion, AQIS considers that perhaps 1 in 1000 notified reports will become an established weed, pest or disease, and of those perhaps only 1 in 10 will become a severe threat (i.e. 1 in 10 000 documented reports). Inevitably, it is easier for some types of organisms to be detected through inspection, such as weed seeds or other plant parts, larger insects or molluscs, whereas most disease organisms (fungi, bacteria and viruses) are detectable only through more costly quarantine assessments. Nursery, stock and crop introductions are all evaluated in this manner, within designated quarantine facilities. Figure 43 shows the trend in verified incursions over the past five years.
Figure 43: Trend in verified plant-related incursions, 1995-2000.
Source: Plant Health Australia (2001)
Insects are the largest category. Fortunately numbers are not great, but a single potentially devastating organism is of much greater concern than many that do not spread.