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In this section you will find detailed information, including national overviews and state and regional level assessments, from the 2000-2002 National Land and Water Resources Audit theme assessments.
Landscape Health In Australia
A rapid assessment of the relative condition of Australia's bioregions and subregions
Gethin Morgan
Environment Australia, 2000
ISBN 0 642 37119 9
Future directions
Limitations of the study
Major limitations of this study relate to the:
- sources of data used, and hence its repeatability; and
- currency of the data used.
The absence of relevant or current data for some attributes meant that expert knowledge was the most suitable data to provide this snapshot of current relativities in landscape health. This means that:
- some of the attribute data presented cannot be reliably compared with the results of subsequent subregional assessments to determine trends;
- some data is not strictly comparable between States. This also applies to some of the more quantitative data used, which was collected differently by the different States and Territory, and sometimes was collected over different time periods.
In general these issues of relativity between the various data sources for a particular attribute have been minimised by using classed data in the analyses. Where the particular attribute class for a subregion is critical for a particular decision, the primary data needs to be checked to determine how close to the class threshold the subregion lies and how accurate that data is. Any final assessment should then be made in that context.
Data needs
The fundamental constraints to this study are the absence of appropriate data sets to determine current landscape health, and the lack of monitoring data through time that would enable trends in health to be identified and quantified. In the absence of this data, it has been necessary to use surrogate indicators that, although clearly linked to landscape health and the status of subregional biodiversity, are not underpinned by a body of clear and irrefutable scientific literature that demonstrates the landscape or ecosystem scale processes involved. In particular:
- there is no ecological basis for identifying clear thresholds for the long-term landscape changes that are the focus of this study; and
- the ecology of Australian landscapes and their biota is an area requiring urgent, coordinated and intensive study.
Fundamental data sets to support the study of landscape ecology are also conspicuously lacking. These include:
A consistent map of the major land types of the continent.
This is one of the principle data sets required for landscape health assessments. It would identify the elements of the geomorphic patterns of the continent, and the associated vegetation and soil types, and provide the necessary framework for ecological studies into landscape processes. The most appropriate scale in the short to medium term would vary between 1:100000 or larger in the intensive use zone, and 1:250000 in the extensive use zone.
Extent of native vegetation
For the purposes of improving reporting within the framework established by this project a fundamental requirement is for current information. Queensland has the most current (1999) state-wide map of the remaining extent of native vegetation in the intensive use zone. Queensland is also the only jurisdiction regularly mapping state-wide change in the extent of native vegetation, and is therefore the only State in which it is possible to track rates of clearing.
Soil condition
No State or Territory has a soil map that shows change in soil characteristics due to European land use; most do not have a soil map of a suitable scale to investigate such change. The absence of suitable land use maps is also a major constraint, the national land use coverage used having considerable limitations of scale, particularly with regard to the extent of cultivated areas.
Grazing intensity
The 'Biophysical Naturalness' cover used as an indicator of grazing intensity requires updating to incorporate new watering points, vegetation mapping and land use change.
Species level information
Accurate information at the species level is also required, to more confidently describe the distribution, density and trend of threatened native species, and of significant introduced species. This information is particularly limiting in the extensive use zone.
Institutional issues
Overriding all these information constraints is the problem that where information concerning a particular attribute has been collected over time, it has rarely been assessed using the same methods. This is due to changing technology, and to the lack of continuity in funding of particular work groups or organisations. To improve the capacity for national landscape health assessments both increased levels of resourcing and institutional leadership are required.
Further data analysis
Values allocated to attributes are based on the best information available within the constraints of the project. A broader review of some of the expert data (e.g. distribution, densities and trends in weeds and feral animals) would refine the analysis, adding to its value, particularly for State-level uses. Any changes are likely to be minor without the collection of new field data.
While the continental landscape stress synthesis provides a general overview of relativities in landscape health and biodiversity in Australia, it reflects attributes selected as indicators, and thresholds used. A sensitivity analysis to explore the impact of changes in classes or thresholds on relativities between subregions would be desirable for this report to be used to guide Commonwealth priorities in its environmental initiatives.
Other combinations of attributes, and the introduction of weighting, could be explored. For example the relative number of threatened species recently recorded in a subregion may be less an indicator of stress than the number of locally extinct species (i.e. those no longer present in the subregion) and could be dropped from the stress analysis. Similarly the relative significance of the different attributes as indicators of biodiversity decline, and any associated thresholds, may differ between subregions. Attributes are also likely to differ in significance as a subregion becomes more stressed. For example the impact of weeds on biodiversity in a fragmented natural landscape is likely to increase rapidly as remnant size falls below particular thresholds.
To gain a more accurate understanding of relativities between subregions, the attributes need to be assessed individually for each subregion, and the differences assessed on this basis.
The subregions also provide a framework to characterise and assess wetlands, suites of particular wetlands being characteristic of particular subregions. The likely health of lacustrine, riverine and estuarine wetlands could be approximated by using the condition attributes of the subregions within their catchments, or, if their catchments lie within a single subregion, the condition attributes of that subregion. This is akin to the assessment methods that have been employed in the Audit's Catchment Condition project.
Improving Australia's capacity to assess landscape health.
The subregions used in this study provide a robust framework for national, landscape-scale reporting. However, consultation and refinement is required if they are to be accepted by all agencies within the jurisdictions. This will need collaboration between the agencies responsible for biodiversity assessment, and those with responsibility for soil and land survey. Refinement is not just necessary for its broader relevance, but also to ensure that the reporting framework is relatively stable at a suitable scale for national reporting.
Deficiencies that need to be addressed in the shorter term to enable the framework to be more useful for other land assessment and planning purposes include:
- delineation of equivalent subregions in the bioregions of eastern New South Wales; and
- review and delineation of subregions at a larger scale in the Northern Territory.
If ecosystem-scale issues are to be used in national reporting, a national map of integrated mapping units that reflect the major land types of the continent will be necessary to ensure uniformity and consistency.
With these fundamental, hierarchical mapping units in place and stable, the major needs in reporting would be:
- national consistency in attributes;
- consistency in the methods of collection and assessment of relevant information; and
- regularity in collection.
While appropriate attributes are defined within the national State of the Environment framework, consistency and regularity of data collection in some attributes remains a significant obstaclemainly due to frequent policy and organisational changes. This lack of continuity in the collection of nationally relevant landscape information needs to be addressed Australia wide. The current development of the Australian Collaborative Rangelands Information System may provide some direction to this critical issue.
Potential applications
This study indicates the relative significance of issues associated with landscape health in general and biodiversity status in particular for each subregion of Australia's bioregions. It shows the geographic distribution of these issues, and their relative magnitude. It provides a broad indication of the scale of the challenges Australia faces in maintaining or restoring landscape health, yet enables these challenges to be broken down into geographic extents that can be used to develop and guide responses.
Each subregion requires specific institutional or on-ground responses that can only be determined by more detailed subregional assessments. This study provides the context and priorities for that closer assessment, and a framework for the extrapolation of its results across subregions with similar issues or needs. This analysis would provide a more precise estimate of the needs and costs of sustaining regional landscapes in Australia, and provide clear directions for community and government to do so.
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