Australian Natural Resources Atlas

Natural Resource Topics

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

Introduction

This report is part of the National Land and Water Resources Audit (Audit) assessment of the condition of the natural resources of Australia and examines bioregional landscapes and associated biodiversity. This report provides the foundation for the Audit's Australia-wide biodiversity assessment.

The Landscape Health in Australia Project was jointly funded and supported by the State of the Environment Reporting and the National Reserves System sections of Environment Australia, and the National Land and Water Resources Audit. It is a part of the Audit's Ecosystem Health Theme. This theme focuses on landscape, catchment, river, and estuary, health at a systems level looking at:

This report addresses the health of regional landscapes from a nature conservation perspective considering the status of their natural ecosystems and associated biodiversity values.

Broad indications of environmental decline across Australia include soil erosion, weed infestations, dryland salinity, and regional extinctions of fauna. The accumulating impact of European patterns of land use profoundly affects many Australian landscapes, ecosystems and their biological diversity. An understanding of relativities in landscape health is needed to help guide the urgent and effective responses required to prevent further long-term damage to landscape health in Australia, and where necessary repair the damage already done.

The primary aim of this project was to use existing information to assess regional differences in the health of landscapes from a natural ecosystems perspective to help guide national initiatives for biodiversity conservation.

The project was a collaborative initiative with the States and Territories, and was supported by a working group of their biodiversity conservation experts. The landscape framework used and the landscape attributes assessed were agreed between the working group, Environment Australia and the Audit, within the framework of established State of the Environment national indicators (Saunders et al. 1998, ANZECC 2000).

Landscape is a scale of study and understanding beyond the paddock or the farm. A landscape includes the:

A landscape may be drained by a number of catchments, and the characteristics of that landscape will apply to those parts of those catchments. While a catchment may contain many different geologies and associated landforms, soils and vegetation, a landscape has a characteristic suite and pattern of these, clearly differentiating it from adjacent landscapes.

Health is a concept requiring a reference point or baseline against which a relative assessment is made. The processes maintaining landscape health need to be understood so that suitable indicators of relative health can be identified. Trends in these indicators can be used to further understand the processes at work. To determine national trends a network of representative points or areas is required, where these indicators can be regularly monitored using standardised methods. In Australia, landscape change has been so rapid that there is no baseline information for most of the continent and there is little systematic long-term monitoring. Much remains unknown ecologically, and an understanding of landscape scale processes is at best rudimentary.

Attributes included:

Data sources included readily available national and State data, and expert knowledge. Other attributes were initially included but could not be used due to the absence of suitable data or the difficulty of addressing complex attributes in such a short time (e.g. despite its major influence on the health of many Australian ecosystems, the impacts of changes in fire regime could not be reported on). Most attributes relate to the current condition of the subregions. Trend in condition was also assessed for some attributes.

Reporting polygons used in this project are subregions of an IBRA 5 (see Environment Australia 2000a). These subregions delineate the major geomorphic patterns within the IBRA 5 bioregions and provide a robust framework with greater resolution for analysing landscape distribution and environmental impacts of past and present land uses. Three hundred and fifty-four subregions have been delineated, compared with the 85 bioregions of IBRA 5 (Appendix 1). The bioregions in Tasmania are treated as subregions for the purposes of this project. Subregions in the Northern Territory are indicative only. In New South Wales, the coastal analyses were bioregional, not subregional as no agreed subregional classification exists.

The continent was divided into two discrete zones for analysis and reporting of some attributes: the intensive use zone (subregions where extensive clearing has occurred or is occurring) and the extensive use zone (where land use predominantly relies on the use of native vegetation) (Figure 1). The concept is similar to extensive and intensive land use zones used by Graetz et al. 1995, but unlike thesedefined by 1:250000 scale map sheetsthey are defined by grouping subregions. Subregions in the intensive use zone have generally been cleared of more than 10% of the original native vegetation.

Data sources are a combination of published and unpublished State and national data sets, and expert knowledge drawn largely from the State and Territory land resource and nature conservation agencies. Attribute values were derived for each subregion and classed, to reduce the scale of variation in the quality and accuracy of the data used, and to simplify analysis and presentation (Appendix 2). Classed condition and trend attribute values are presented in Appendices 3 and 4 and as national maps. Numerical data are available as data through the Atlas.

Table 1: Data used for each attribute.
Attributes used Data source (qualitative/quantitative)
Condition attributes
Current extent of native vegetation State vegetation coverages - quantitative classification
Degree of connectivity in native vegetation State vegetation coverages - descriptive - qualitative classification.
Conservation of Native vegetation State vegetation coverages intersected by protected areas database (Environment Australia 1999) - quantitative
Native vegetation in tenures associated with conservative land use practices State vegetation coverages intersected by national land use map (Bureau of Resource Sciences 2000) - quantitative, classification of 'association with conservative land use practices' - qualitative
Condition of native vegetation State vegetation coverages intersected by 'biophysical naturalness' an attribute of the national data set compiled for the National Wilderness Inventory (Lesslie & Maslen 1995) - quantitative, relationship to intensity of grazing semi-quantitative (Landsberg et al. 1999).
Extent of dryland salinity Audit Australian Dryland Salinity Assessment 2000 - quantitative assessment of groundwater depth (Western Australia, South Australia, Victoria, New South Wales) - qualitative hazard assessment (Tasmania, Queensland, Northern Territory).
Degree of changed hydrological conditions State/subregion-based expert knowledge based on national land use map & native vegetation condition - descriptive classification - qualitative.
Distribution and density of non-indigenous plant species (weeds) of national importance State/subregion-based expert knowledge (absent, occasional, common, abundant) - qualitative.
Distribution and density of non-indigenous vertebrate species (feral animals) of national importance State/subregion-based expert knowledge (absent, occasional, common, abundant) - qualitative.
Threatened vertebrate animals and plants Commonwealth listings (Environment Australia 1999) - quantitative site based plus distribution modelling - qualitative expert knowledge
At risk ecological communities and threatened species Quantitative extent mapping (Queensland, Victoria and Western Australian), quantitative land form surrogates (New South Wales), extent mapping and expert (qualitative) knowledge (South Australia, Tasmania), qualitative condition assessment (Queensland).
Trend attributes
Current rates of clearing of native vegetation State and Commonwealth vegetation coverages - quantitative
Trends in the incidences of non-indigenous plant species (weeds) of national importance State/subregion-based expert knowledge (increasing, decreasing, stable, no records) - qualitative.
Trends in the incidences of non-indigenous vertebrate species (feral animals) of national importance State/subregion-based expert knowledge (increasing, decreasing, stable, no records) - qualitative.
Trends in dryland salinity Audit Australian Dryland Salinity Assessment 2000 - quantitative assessment of groundwater depth and trends (Western Australia, South Australia, Victoria, New South Wales) - qualitative hazard assessment (Tasmania, Queensland, Northern Territory).
Inappropriate fire regimes State/subregion-based expert knowledge - qualitative classification.

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