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
The state of the Australian lands is reported using the Pressure, Condition, Response and Implications (PCRI) model. The available data on land indicators has been grouped into six broad issues:
- accelerated erosion and loss of surface soil,
- physical changes to natural habitats,
- introduction of novel biota into native habitats and communities,
- secondary salinity and acidity of soil,
- soil nutrient and carbon cycling, and
- soil and land pollution.
The principal findings of SoE for 2001 are summarised in Table 1. Overall the level of response to environmental change are improving across all issues however, the effectiveness of these responses in the face of generally increasing pressures is a matter of concern. The result is that while indicators of erosion show improvement, in part reflecting a wetter period, the indicators of landscape function grouped under salinity, acidity, nutrients and carbon all indicate that an increased level of response will be required if land sustainability is to be achieved. The period 1995-2000 corresponded to a La Nia (wet) climatic phase, whereas the 1996 SoE Report described the previous five-year El Nio (dry) phase. The difference in vegetation response, clearly visible in continental greening (see Figure 1) has been fortuitously enhanced by reductions in grazing by sheep and rabbits, that clearly show the massive influence of total grazing pressure on many aspects of Australian ecosystems.
Figure 1: NOAA images of flush difference, 1993-1994 and 1998-1989, showing differences in seasonal greening between dry and wet phases of the Southern Oscillation.
Source: Environment Australia 2001 using National Oceanic and Atmospheric Administration (NOAA) data
|Altered habitats||Constant / increasing||Deteriorating||Improving|
|Novel biota incursions||Constant or increasing||Static or deteriorating||Constant or increasing|
|Secondary salinity and acidity||Constant or increasing||Static or deteriorating||Increasing (salinity only)|
|Nutrient and carbon cycling||Constant or increasing||Static||Increasing (carbon)|
|Pollution||No trend assessable, no previous data||Variable; some improving, some unknown||Increasing from a low base|
Of particular concern is the deteriorating landscape hydrological balance with resultant salinity and the continuing levels of unsophisticated irrigation and clearing of perennial vegetation that will inevitably lead to more salinity.
Also of concern are the progressive changes in soil pH and structure which if not addressed through adequate liming, gypsum and mulching have the potential to rival salinity as an issue at the landscape scale.