Australia's Natural Resources
1997-2002 and beyond
National Land and Water Resources Audit, 2002
Key Findings—Biodiversity
Vegetation
Australia now has a standardised approach to collating native vegetation information.
- Through an Australia-wide partnership a hierarchical classification of Australia's native vegetation has been implemented. This can be summarised by presenting native vegetation in major vegetation groups.
Figure 46. Major native vegetation groups in Australia.
 |
There have been significant changes to the extent of native vegetation.
- About 33% of Australia's native vegetation in the intensively used areas, primarily agricultural and urban land uses, have been cleared or modified.
Figure 47. Extent of native vegetation in Australia.
 |
The level of clearing of native vegetation in each State and Territory varies substantially.
- Re-vegetation programs and protective management programs can be targeted according to the level of clearing of vegetation in each State and Territory. At the State scale, for example, Northern Territory, with the most intact native vegetation might be a priority for protective management activities whereas Victoria, with the least native vegetation intact, might be a priority for targeted re-vegetation programs under Bushcare.
Table 7. Native vegetation remaining in the intensively used (as defined by Graetz et al. 1995) areas of Australia.
Area native vegetation remaining
(km2)Percent remaining
(%)Victoria 84 541 37 Western Australia 234 423 56 South Australia 174 966 64 New South Wales 470 604 67 Australian Capital Territory 1 620 69 Queensland 772 452 72 Tasmania 42 520 80 Northern Territory 186 629 98 Australia (intensive land use zone) 1 967 754 68
The vegetation types most impacted by clearing can now be defined.
- Mapping in major vegetation groups provides context for finer-scale vegetation management and conservation activities.
Figure 48. Area (km2) of pre-European and present major vegetation groups in Australia.
 |
Clearing and fire are key threatening processes for Australia's native vegetation.
- Clearing of native vegetation remains the single most significant threat to terrestrial biodiversity. Land clearing has decreased in most States and Territories. Likewise, determining and then applying appropriate fire regimes is a major challenge for Australia's biodiversity managers. Comparative estimates of the population density of woodland birds, for example, indicate that between 1000 and 2000 birds permanently lose their habitat for every 100 ha of woodland cleared (Glanzig & Kennedy 2000).
Figure 49. Cleared major vegetation groups.
 |
The current protection status of the major vegetation groups varies substantially.
- With the development through the Audit of Australia-wide consistent mapping and classification of native vegetation, managers can now assess the conservation status of major plant communities and plan further reservations accordingly.
Table 8. Area (km2) of major vegetation groups in protected areas.
- indicates that this major vegetation group does not exist in a particular jurisdiction or that the scale and type of mapping compiled has not captured this major vegetation groupMajor vegetation group Western
AustraliaNorthern
TerritorySouth
AustraliaQueensland New
South
WalesAustralian
Capital
TerritoryVictoria Tasmania Australia Rainforest and vine thickets - 265 - 5 058 1 545 - 134 4 241 11 244 Eucalypt tall open forests 554 - - 48 1 286 4 4 550 1 569 8 011 Eucalypt open forests 1 705 6 806 87 4 016 21 580 858 2 844 3 657 41 552 Eucalypt low open forests 106 70 17 104 509 42 77 31 957 Eucalypt woodlands 9 543 4 280 1 311 15 437 10 478 179 7 887 1 420 50 534 Acacia forests and woodlands 8 065 10 659 3 326 539 - 97 6 12 701 Callitris forests and woodlands - - 220 67 1 157 4 279 - 1 728 Casuarina forests and woodlands 163 - 7 363 223 647 2 42 16 8 457 Melaleuca forests and woodlands 348 1 695 1 5 744 1 - 24 - 7 812 Other forests and woodlands 751 127 10 731 2 197 2 - 1 290 252 15 350 Eucalypt open woodlands 4 236 8 190 7 050 6 990 2 166 48 333 33 29 047 Tropical eucalypt woodlands/grasslands 10 073 17 072 - 1 757 - - - - 28 903 Acacia open woodlands 75 24 8 953 1 899 8 - - - 10 959 Mallee woodlands and shrublands 14 763 1 318 47 809 - 2 919 - 8 675 - 75 484 Low closed forests and closed shrublands 276 - 2 115 31 - 403 1 388 2 214 Acacia shrublands 12 427 1 305 2 748 2 073 1 664 - 5 3 20 225 Other shrublands 4 291 1 9 374 1 863 23 7 2 390 329 18 278 Heath 5 294 - 2 011 140 730 9 1 405 765 10 354 Tussock grasslands 2 314 701 6 166 5 033 1 994 40 165 144 16 556 Hummock grasslands 54 689 5 870 54 404 10 441 - - - - 125 403 Other grasslands, herblands, sedgelands and rushlands 873 1 913 261 405 204 - 395 6 385 10 437 Chenopod shrubs, samphire shrub and forblands 21 363 441 32 696 2 003 740 - 704 5 57 952 Mangroves, tidal mudflats, samphires and bare areas, claypans, sand, rock, salt lakes, lagoons, lakes 3 127 265 22 900 633 300 10 272 733 28 240
Analysis of fragmentation of native vegetation at the subregional scale provides an information base for setting priorities for re-vegetation and protection through reservation of remnants.
- Of Australia's 354 subregions, 42 have less than 30% of native vegetation remaining, with 22 of these having the remaining vegetation highly fragmented. These subregions occur in south-western Western Australia, south-eastern South Australia, central and western Victoria, the New England Tablelands in New South Wales and southern and central eastern Queensland. These subregions are likely to be priority areas for strategic re-vegetation, re-establishing linkages and wildlife corridors across the landscape. Protective management of the native vegetation remnants in these subregions is also an imperative and provides a cost-effective way to retain native vegetation in these landscapes.
Figure 50. Fragmentation classes in subregions.
 |
Nearly half of Australia's subregions are in excellent environmental health, presenting opportunities for protective management.
- Australia's 354 subregions were assigned to one of a six-tiered classification of the extent of 'landscape stress'. This assessment took account of the extent and fragmentation of native vegetation; threatened ecosystems and species; and frequency of salinity, weeds and feral animals. One hundred and fifty-two regions are in relatively good condition. Protective management activities across all tenures in these subregions are likely to be most cost-effective and will ensure these subregions remain in good condition. Approximately 10% of Australia's subregions have been identified as stressed, with 17 subregions appearing in the highest stress category and a further 20 in the second tier, together representing 10% of the nation's subregions. These subregions would require substantial investment to regain key conservation values.
Figure 51. Continental landscape stress.
 |
Australia is increasingly focusing on strategic weed management
- Australia has defined 20 weeds as 'weeds of national significance'. A number, including lantana and parthenium weed have the potential to colonise suitable habitats across much of Australia and are expanding aggressively. In 1955, for example, parthenium, a native of the Caribbean, was first identified in northern Queensland. Between 1955 and 1979 it spread through 170 000 km2 of north-eastern Queensland, with lighter infestations gradually extending southwards. Parthenium reached the New South Wales border in 1979 and Victoria by 1989. Local infestations have been found in the Roper River area of the Northern Territory and the Kimberleys. Other long-established weeds such as blackberries have probably reached the limits of their ecological adaptation and have had considerable impact on natural and agricultural ecosystems. They are still proving difficult to manage, despite the introduction of biological control measures.
Figure 52. Distribution of parthenium weed.
 |
Figure 53. Extent of blackberry distribution (2000).
 |
Mammals
Australia has a unique fauna.
- The 305 indigenous species of mammals include 258 (85%) that are endemic to Australia. The remainder, mostly bats, are shared with New Guinea and nearby islands.
Figure 54. Species richness (number of species) of the pre-European mammal fauna in each bioregion.
 |
Twenty-six exotic species of mammals have been introduced to Australia.
- Competitive pressures from introduced species have contributed to declines in populations and losses by extinction of Australian mammals.
Figure 55. Known and predicted occurrences of threatened vertebrate fauna.
 |
Australia's vertebrate pests have vastly expanded in range since their introduction.
- Despite some success at control measures, feral goats, which have a serious impact on plant biodiversity, remain in high density in some areas. Feral cats, threatening many small native mammals, have become ubiquitous over most of the country. Policy measures that encourage continued effort to reduce vertebrate pest numbers can be targeted based on the now documented ranges of each particular feral animal. Such measures would be part of protective management activities across all tenures to retain Australia's biodiversity.
Figure 56. Goats have become a major feral pest in southern and western Australia.
 |
Figure 57. Feral cats are widely distributed across the Australian landscape.
 |
Australia's mammal populations require strategic and targeted approaches.
- Some mammal species have contracted to less than 10% of the regions they originally occupied (Figure 58) principally in the desert and cereal crop regions.
Figure 58. Number of mammal species, of the original fauna in each region, whose range has contracted from >90% of the regions original occupied, showing a measure of environmental change.
 |
Rehabilitation and protective management to conserve remnant biodiversity
- Rehabilitation and protective management are essential in those bioregions that now contain populations of mammal species which were once widespread. The Avon wheatbelt in the south west of Western Australia and channel country of the Lake Eyre Basin are examples of bioregional refuges for mammals.
Figure 59. Number of mammal species that have undergone Australia-wide range reduction > 50%.
 |
Rivers & Estuaries
River reaches provide a spatial framework for river management and monitoring.
- A river reach is a section of river with relatively uniform physical characteristics. Fourteen thousand, six hundred and six reaches have been defined for Australia's more intensively used catchments. With further finetuning to meet State and Territory needs, these reaches will provide a rigorous and consistent reporting framework for tracking progress in river management.
Figure 60. Climate zones in Australia relevant to river condition-also showing those reaches assessed for the Audit's work on rivers.
 |
Aquatic biota, as represented by macro-invertebrate indicator species provide a partial measure of river condition.
- The collated National River Health Program – Australian River Assessment Scheme (AusRivAS) data sets suggest that, based on macro-invertebrates as indicators, little change from apparently natural conditions has occurred in 67% of river reach length. Within the remaining 33% of river length with impaired aquatic biota, almost 25% has lost between one fifth and one half of the macro-invertebrate groups used as indicators of river biodiversity.
Figure 61. Condition of river reaches based on the aquatic biota (macro-invertebrate ) index.
 |
An assessment of environmental modification provides the key to management opportunities for Australia's rivers.
- Over 85% of river length was classified as having undergone some environmental modification, including catchment disturbance, reduced riparian vegetation, hydrological disturbance and increases in the load of suspended sediments and nutrients. New South Wales, South Australia and Western Australia have the greatest percentage of modified river length (97%, 96% and 93% respectively) and the Northern Territory has the smallest amount (34%).
Table 9. River environment index results for each State and Territory.
Total length of reach (km) in each category and percentage of total in parentheses Percent of total length with data Largely unmodified Moderately modified Substantially modified Extensively modified Queensland 8 743 (13) 48 214 (71) 10 599 (16) 0 (0) 93 New South Wales 1 619 (3) 39 232 (68) 17 089 (29) 18 (0) 97 Australian Capital Territory 43 (16) 191 (71) 36 (13) 0 (0) 100 Victoria 3 085 (20) 9 042 (60) 3 099 (20) 0 (0) 97 Tasmania 2 028 (37) 3 250 (59) 194 (4) 0 (0) 98 South Australia 299 (4) 4 666 (61) 2 635 (35) 0 (0) 79 Western Australia 1 487 (7) 15 927 (78) 2 929 (14) 12 (1) 80 Northern Territory 9 165 (66) 4 630 (34) 0 (0) 0 (0) 67 Total 26 468 (14) 125 152 (66) 36 581 (19) 31 (1) 90
Riparian and in-stream habitats are key management factors for the health of Australia's rivers.
- Protection of existing riparian habitat and its re-establishment in most catchments together with improved catchment management to minimise sediment and nutrient inputs is essential. Largely unmodified rivers occur especially in far north Queensland, eastern Victoria and Tasmania. These require protective management to ensure their condition is maintained. Rivers with the most modified condition are in parts of the Murray-Darling Basin, the Western Australian wheatbelt, western Victoria and the South Australian cropping areas. Riparian areas of many of these rivers are dominated by weeds.
Figure 62. Condition of river reaches.
 |
Native fish populations are a key indicator of river health for which we need more information.
- Issues for management include barriers to fish movement, poor water quality, reduction in habitat and competition from exotic species. These impact on fish populations and need to be analysed for each of our major river basins. Some species of freshwater crayfish are also considered to be at risk, primarily from loss of habitat.
Reductions in Australia's waterbird populations reflect the decline in wetland condition.
- Fifty percent of Australia's inland waterbirds are listed as vulnerable or threatened, mainly from loss of wetland and riparian habitat. Further assessment is required to provide input to management.
Management needs and opportunities for investment vary.
- Most river reaches in Queensland and northern coastal New South Wales, western Victoria and south-west Western Australia have largely unmodified riparian habitat. The condition of these rivers is affected by very high instream nutrient and suspended sediment loads. Sediment and nutrient sources vary in relative proportions, providing an indication of where management activities are likely to deliver the highest return (Figures 63, 64). The total loads vary for these regions (Figure 19).
Figure 63. Proportion of phosphorus (%) from different types of erosion in the assessed regions.
 |
Figure 64. Proportion of nitrogen (%) from different types of erosion in the assessed regions.
 |
The fate of nitrogen and phosphorus entering rivers also varies.
- With an understanding of the location of nutrient change (deposition or loss), managers can start to understand key differences in processes and management opportunities. In far north Queensland, for example, less than 40% of phosphorus and nitrogen ends up on floodplains, with the remainder transported down river to estuary. In the Burdekin and Fitzroy, further south, more than 60% of the phosphorus is captured by floodplains. The total loads vary for these regions (Figure 19).
Figure 65. Proportion of phosphorus (%) to different locations of deposition and export to the coast in the assessed regions.
 |
Figure 66. Proportion of nitrogen (%) to different locations of deposition and export to the coast in the assessed regions.
 |
An understanding of estuary type allows managers to identify the key sinks for sediments and nutrients.
- The dominant processes that drive estuary behaviour determine the susceptibility of estuaries and their adjacent near-shore areas to various catchment pressures such as changes in turbidity, circulation and sediment trapping/nutrient enrichment. Sedimentation caused by catchment erosion, for example, is particularly significant for wave-dominant estuary systems because this type of estuary has a high tendency to trap sediment in the lake environments that characterise them. In comparison, tide-dominant estuaries efficiently transport sediments to the near-shore marine zone with consequential marine environmental impacts.
Figure 67. Estuary types and their typical characteristics.
 |
For the 1000 estuaries assessed, key processes and therefore management opportunities and constraints vary.
- In much of southern Australia, wave-dominated systems are common, with most of the catchment-derived sediment and enrichments staying within the estuaries. For much of tropical Australia, tide-dominated systems are common, with the estuary acting more as a conduit than a sink. In these systems much of the catchment-derived sediments and enrichments are exported to the near-shore zone, such as to the Great Barrier Reef lagoon.
Figure 68. Distribution of Australia's estuaries by process type.
 |
Half of Australia's 1000 estuaries are in near-pristine condition.
- Of the remaining 50% of Australia's estuaries that are not in near-pristine condition, a further 22% are largely unmodified, 19% are considered modified and 9% are regarded as extensively modified.
Figure 69. Location of the near-pristine, the largely unmodified, the modified, and the extensively modified Australian estuaries.
 |
Estuaries have value as productive ecosystems and a key role in biodiversity and fisheries.
- Many fish species are estuary-dependent in larval or juvenile phases. Protective management arrangements for Australia's pristine estuaries will deliver multiple benefits. They will also be more effective in the long term obviating the necessity to undertake rehabilitation that may be expensive or even not possible. These pristine estuaries are spread around the States and provide the keystone for an effective estuarine and marine management program.
Figure 70. Condition of Australian estuaries by State and Territory (%).