In the first issue of Measures of Australia's Progress, separate headline progress dimensions of Biodiversity, Land clearance, Inland waters and Land degradation were presented along with supplementary dimensions entitled Invasive species and Land use. In this issue those dimensions have been combined into one headline dimension The natural landscape.
The Australian landscape comprises Australia's land and water and the native and introduced plants and animals that rely on them. The three are inextricably linked. Changes in the condition of Australia's land, such as increased salinity, can affect inland waters and biodiversity. Changes in the health of our inland waters (such as reduced river flow) can affect biodiversity. And changes in biodiversity (such as the clearing of native vegetation) can lead to land degradation and a decline in the health of inland waterways.
The commentary that follows comprises four subsections:
- Biodiversity: Our native plants, animals and ecosystems bring important economic benefits, are valuable to society and are globally important. Native bushland has cultural, aesthetic and recreational importance to many Australians. Most importantly, the ways in which organisms interact with each other and their environment are important to human survival: we rely on ecosystems that function properly for clean air and water and healthy soil. Headline indicators that consider changes in the condition of several groups of threatened species, and the annual area of land cleared are presented. The commentary includes information about the area of land in conservation reserves and action that is being taken to protect Australian biodiversity.
- Invasive species: An invasive species can be defined as a species occurring as a result of human activities (deliberate or accidental) outside its accepted normal distribution, which threatens valued environmental, agricultural or personal resources by the damage it causes. Invasive species include both foreign and native plants and animals. Not all introduced species (foreign species or those living in one part of Australia but native to another) are invasive: that is not all such species threaten valued resources by the damage they cause. The introduction of invasive species is a continual process, and they are an environmental, social and economic problem. Invasive species occur in all habitats, and many invasive plants and animals are increasing in number and spreading across Australia. They exert a major pressure on biodiversity, and can degrade the land and harm water quality. No headline indicators are presented, but the commentary includes information on the spread of exotic weeds and mammal species.
- Land: The condition of the soil covering Australia's land has a critical impact on our terrestrial ecosystems. Our soil resources are an important natural asset, and their degradation is a significant concern to Australian farmers, governments and the general public. Meanwhile the way in which Australia's land is used has a significant impact on our biodiversity and Inland waters. A headline indicator that considers the assets at risk of salinity is presented, and information on land use and forest cover is presented.
The commentary and statistics that follow use a range of information, much of it from outside of the Australian Bureau of Statistics. Two important sources of information, which we have used considerably, are The State of the Environment Report for 2001, and various publications from the National Land and Water Resources Audit. These are two of the most significant sources of detailed environmental data for Australia.
- Inland waters: Water is fundamental to the survival of people and other organisms. Apart from drinking water, much of our economy (agriculture in particular) relies on water. The condition of freshwater ecosystems has a critical impact on the wider environment. A headline indicator that considers the proportion of Australia's water management areas where water use is approaching or exceeding sustainable limits. Information on Australian water use and water extractions from the Murray-Darling Basin is also included.
Between 1993 and 2003 the number of terrestrial bird and mammal species listed as extinct, endangered or vulnerable rose by 40% from 118 to 165.
Although land clearing continued, the rate of clearance decreased by about 40% between 1991 and 2001. Estimates indicate that about 248,000 hectares (ha) of land were cleared in 2001, around 70% in Queensland.
Biodiversity: Extinct, endangered and vulnerable birds and mammals(a)
Biodiversity: Annual area of land cleared (hectares)
|The relationship of biodiversity to progress||Our native plants, animals and ecosystems bring significant economic benefits, are valuable to society and are globally important. Most importantly, the ways in which organisms interact with each other and their environment are important to human survival: we rely on ecosystems that function properly for clean air and water and healthy soil.|
|About the headline indicators and their limitations: Threatened bird and mammal species, annual area of land cleared||No single indicator can hope to encapsulate biodiversity, and so we focus on two aspects: the numbers of extinct and threatened Australian birds and mammals; and the clearing of native vegetation.
Although the numbers of threatened birds and mammals are only a small part of the overall biological diversity, a decline in these groups of species threatens ecological processes and can point to a wider decline in biodiversity. Changes to the list of threatened species should be treated cautiously as species can be added to or removed from the list as their status changes or due to improved knowledge.
Land clearing is a key threat to biodiversity.1 The land clearing estimates include information about forest conversion (land cleared for the first time) and reclearing, both of which have environmental impacts. The figures do not distinguish between the kinds of vegetation cleared.
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|Biodiversity: Other indicators||Threatened species trend, proportion of bioregions; Area of land in conservation reserves.|
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|Some differences within Australia||The National Land and Water Resources Audit report that threatened birds are declining across 240 of Australia's 384 subregions and threatened mammals are rapidly declining in 20 subregions and declining in 174 subregions.
Land clearance since 1788 has mainly occurred in southern and eastern Australia. More than 70% of land cleared in 2001 was in Queensland, but this is likey to reduce as a result of recent policy initiatives by the Australian and Queensland Governments.
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|Links to other dimensions||See also the commentaries The natural landscape - invasive species, land and water, Oceans and estuaries, and National income.|
In 2000, about 5.7 million hectares (ha) of Australia were assessed as having a high potential to develop dryland salinity through shallow or rising water tables.
The damming and regulation of waterways and extractions of both surface and ground water are leading to a continuing deterioration of the health of water bodies, while increasing salinity is causing deterioration in many areas. About one-quarter of Australia’s surface water management areas are close to, or have exceeded, sustainable extraction limits.
Salinity, assets at risk in areas of high potential(a) - 2000
Water management areas and units(a), proportion where use exceeded 70% of sustainable limits(b) - 2000
The natural landscape - biodiversity
|The relationship of land and inland water to progress||Our soil resources are an important natural asset. Degraded soil reduces agricultural productivity, while salinity can damage buildings and infrastructure such as water pipes, roads and sewers. Degradation can also damage habitat for wildlife, kill micro-organisms that live in the soil, and harm the quality of our inland waters.
Water is fundamental to the survival of people and other organisms. Apart from drinking water, much of our economy (agriculture in particular) relies on water. The condition of freshwater ecosystems has a critical impact on the wider environment.
|About the headline indicators and their limitations: Land degradation and water management areas used sustainably||There are several forms of soil degradation in Australia. We focus here on dryland salinity, the impacts of which are wider than lost agricultural production and include damage to water resources, biodiversity, pipelines, houses and roads.
Ideally the headline indicator would consider the health of Australia's freshwater ecosystems. But such data are unavailable for much of the country, so we focus on water use, and consider the proportion of Australia's water management areas within which water extraction is thought to be sustainable.
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|Land and water: Other indicators||Water diversions: Murray-Darling Basin; River condition biota index; Net water use; Dams greater than 100 gigalitres; River environment index; Native forest area.|
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|Some differences within Australia||More than half of Australia's dryland salinity problems are predicted to occur in Western Australia by 2050, with the south-west of that State particularly affected. New South Wales had more significantly, severely and extremely impaired river sites than any other state.|
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|Links to other dimensions||See also the commentaries The natural landscape - invasive species, The natural landscape - biodiversity, Oceans and estuaries, and National income.|
Progress and the headline indicators
Our plants, animals and ecosystems bring economic benefits, are valuable to society and are globally important (Australia is recognised as one of 17 'mega-diverse' countries, with ecosystems of exceptional variety and uniqueness2). Most significantly, the ways in which organisms interact with each other and their environment are important to human survival: we rely on ecosystems that function properly for clean air and water and healthy soil.
Ideally, the headline indicator would consider all Australian biodiversity - the abundance and diversity of micro-organisms, plants and animals, the genes they contain and the ecosystems of which they form a part. But to measure change as comprehensively as this would be difficult, if not impossible (more than 60 core indicators for monitoring biodiversity were suggested for National State of the Environment reporting, for example3) and so here we focus on two indicators: changes in the conservation status of one small component of biodiversity - mammals and birds; and the annual area of land cleared.
Mammals and birds
The numbers of threatened species are one aspect of biodiversity that can be measured. Mammals and birds are used as indicator species, as scientists have more information about these groups than many others, and they are often visible in the landscape and the most easily identified. Although the numbers of threatened birds and mammals are only a small part of overall biological diversity, a decline in these groups of species threatens ecological processes and can point to a wider decline in biodiversity.
Changes to the list of threatened species should be treated cautiously. Species can be removed or added because of improved knowledge, not necessarily because they became more or less endangered. Indeed, sometimes new species are discovered, or those thought extinct are rediscovered. That said, over time, if the numbers of threatened birds and mammals increase substantially there is reason to believe that certain species are declining.
Between 1993 and 2003 the number of terrestrial bird and mammal species assessed as extinct, endangered or vulnerable rose by 40% from 118 to 165 (of which 65 were birds and 100 were mammals). In June 2003 just under half of these species were vulnerable, one-third were more seriously threatened (endangered) and the remaining fifth were presumed extinct. There were increases in the numbers of both endangered and vulnerable species, but the rise in species assessed as vulnerable was much higher (84%) than those assessed as endangered (25%).
We do not know how much of this rise is because of new knowledge and how much is because of species decline, but many experts, such as those from the 2001 State of the Environment Committee believe that total Australian biodiversity declined during the 1990s.1
|A longer term view|
Declines in wildlife have occurred in most parts of Australia since European colonisation. Intensive land use, which has played a part in the decline, has been concentrated in the south and east of the country. Habitat loss, through cropping, grazing, forestry, mining and human settlements, has dramatically changed vegetation cover. Figures from the National Land and Water Resources Audit suggest that, since 1788, over 700,000 km2 (about 20%) of woodland and forest have been cleared or thinned, primarily for crops and grazing. A further 130,000 km2 (35%) of mallee have been cleared since 1788, along with 20,000 km2 of heath (45%), over 60,000 km2 (10%) of tussock grassland and smaller areas of other grasslands.4
Since European settlement, land clearance has been concentrated in certain areas and ecosystems. Generally those ecosystems found on the most fertile soil have suffered the highest levels of clearance, and about 90% of vegetation in the eastern temperate zone has been removed.5 Relatively little land clearance has occurred outside of the high rainfall and semiarid zones, although in these areas other pressures such as grazing (both from domestic stock and introduced herbivores), weeds and changed patterns of fire are having an impact on the land. More than 90% of land clearance has occurred in 25 of Australia’s 85 bioregions (areas of land that contain linked ecosystems). These bioregions occur across south-west Western Australia, southern South Australia, most of Victoria and New South Wales, and central and southern Queensland.4
Wildlife has declined in northern and central Australia too, where the level of land clearing has been lower. In the arid zone, about one-third of mammal species are regionally extinct, the highest extinction rate on the Australian mainland, and many birds are declining.6 The extent of cattle grazing, effects of invasive species and changes to fire regimes are factors thought to have led to a decline in many animal species in these areas.
Over the past 200 years 17 mammal species (out of about 270), and a further 7 sub-species, are thought to have become extinct in continental Australia. Fewer than 25 species are believed to have become extinct in the rest of the world over the same period, which means that Australia accounts for over 40% of the world’s mammalian extinctions since 1800.7 Some other mammals, once widespread, now survive only in tiny areas (often islands free of foxes and cats); this isolation and loss of genetic diversity make species less adaptable and more vulnerable to threats such as disease.
More than 20 exotic mammals and 20 exotic birds have become established in Australia since 1788. But it is hard to compare these with the species we have lost. All of the Australian mammals to have become extinct, for example, were found nowhere else in the world. Most of Australia’s exotic bird and mammal species, however, are common elsewhere in the world. Most have brought environmental problems with them since their establishment here.
Since 1993, the Commonwealth Government has maintained a list of threatened and extinct species and subspecies. A species is designated as vulnerable when there is strong evidence that it faces a high risk of extinction in the medium term, and endangered if it faces a very high risk of extinction in the near future. A species is classed as critically endangered if it faces an extremely high risk of extinction in the immediate future and extinct if there is no reasonable doubt that the last member of the species has died.
Threatened species trend(a), proportion of bioregions(b)
|Changes in the condition or status of threatened flowering plants, birds, mammals and reptiles are only a part of overall biological diversity, but a decline in these groups of species threatens ecological processes and can point to a wider decline in biodiversity.|
In 2002, the National Land and Water Resources Audit (NLWRA) released an assessment of Australian biodiversity, that was based on a mixture of qualitative and quantitative data from around the country.8 They reported the median changes in the condition of groups of threatened species in each Australian bioregion.
- Threatened flowering plants were declining across 177 of Australia’s 384 subregions; static in 33 and improving in five.
- Threatened birds were declining across 240 subregions; had gone extinct in a further 14; were static in 38 subregions; and improving in three.
- Threatened mammals were declining in 194 subregions; had gone extinct in 24 subregions; were static in 29 subregions; and improving in four.
- Threatened reptiles were declining in 119 subregions; had gone extinct in 2 subregions; were static in 21 subregions; and improving in 11.
In 2002, the National Land and Water Resources Audit (NLWRA) released an assessment of Australian biodiversity.8 They reported the status of threatened species and found that threatened species were declining in far more areas than they were improving (see box above). Some of the report's conclusions include:
- Over 9% of the Australian landscape was protected for nature conservation, with 67% of Australia's ecosystem diversity captured by national parks and formal reserves and a further 5% in protected areas on private land.
- There are 2,891 threatened ecosystems and ecological communities across Australia, with the highest concentrations in the highly cleared regions of southern and eastern Australia. Nearly half of the threatened ecosystems are eucalypt forest and woodlands with shrubby or grassy understorey that have been extensively cleared.
- The highest number of threatened species occurred in southern and eastern Australia from the southern highlands in Victoria and New South Wales and along the coast from Sydney to north of Brisbane.
- Mammal extinction has been substantial within the past 200 years, and there is evidence that the wave of extinctions is continuing: recent evidence documents major declines in the abundance in a variety of mammal species from the top end of the Northern Territory and the Kimberley region. There has been a massive contraction in the distribution of mammals in arid and semiarid areas.
- Populations of some species of birds have markedly declined over the past 20 years, particularly the grassland, woodland and ground nesting species.
Numbers of species in selected countries(a)
|United States of America|
| (a) Data are approximate only and have been drawn from the World Resources Institute for the purpose of making international comparisons. (b) Breeding species are used because some species are migratory.|
Source: World Resources Institute.
The clearing of native vegetation is a key threat to Australia's terrestrial biodiversity,1 and perhaps the most significant threat to species and ecosystems in eastern Australia.8 Land clearing destroys plants and local ecosystems and removes the food and habitat on which other native species rely. Clearing helps weeds and invasive animals to spread, causes greenhouse gas emissions and can lead to soil degradation, such as erosion and salinity, which in turn can harm water quality. Native bushland has cultural, aesthetic and recreational importance to many Australians.
|More accurate land clearing estimates |
Knowing how much clearing is occurring is problematic, and the figures, from the Australian Greenhouse Office, are estimates. The figures are more accurate than those published in the first issue of Measuring Australia’s Progress. Earlier figures were calculated using satellite imagery which focused on areas of significant land use change. Full continental satellite coverage is now used.
The figures used to include information about land that has been cleared for the first time as well as land that has been re-cleared. They do not distinguish between the kinds of vegetation that has been cleared - for example, whether it formed part of a healthy or a degraded ecosystem. Thus the figures cannot be used to measure the net or quality-adjusted change in vegetation cover. Both clearance and re-clearance of native vegetation have environmental impacts.
Land is cleared for many reasons (particularly agriculture and urban development). Native vegetation is sometimes completely cleared
(if crops are sown, for example). At other times only a proportion of the native vegetation is removed from an area, which may occur when land is used for mining or urban development.
Ideally, the headline indicator would consider the area of native vegetation cover in Australia. Such an indicator would require a weighted measure of the extent and intensities of land clearance and modification: apart from the practical difficulties of putting weights on different types of clearance, few accurate time series data are available and so we use estimates of land clearance from the National Greenhouse Inventory (NGI). The estimates include the majority of intensive clearance of native vegetation.
The estimated 248,000 ha of Australian land cleared in 2001 is 40% smaller than the 415,000 ha cleared in 1991. Of the land cleared in 2001, less than half (120,000 ha) was 'converted' (cleared for the first time), which is less than half the area converted in 1991.
Australia's biodiversity: a world view
|Australia’s botanical diversity|
With over 15,500 species, Australia has more native higher plants (mainly flowering plants)9 than all of Europe (which has 12,500 species),10 and Queensland and Western Australia each contain around 7,500 native species.9 New species are still being discovered, like the Nightcap Oak, a large tree discovered in 2000 in northern NSW. There are possibly 10 times the number of cryptogams (fungi, algae, lichens, mosses, etc.) than higher plants, and we have barely begun to understand them.
Australia's biodiversity is very rich. In 1998 Conservation International recognised 17 countries as mega-diverse because of their extraordinarily rich biodiversity, and together they account for some two-thirds of the world's species. Australia and the USA are the only two developed countries classed as mega-diverse.11
Australia is a large country and contains a great variety of habitats and ecosystems, from coral reefs and tropical rainforests to temperate woodland, deserts, semi-arid rangelands and alpine grassland. It is, therefore, likely to have more species than many countries by virtue of size alone. But as the table shows, our fauna is highly endemic (that is, many Australian species are found nowhere else on Earth). About 90% of our reptiles and frog species are endemic, and about 80% of our mammals and 85% of flowering plants.7 We have 200 species of freshwater fish, 90% of which are endemic. Also, of the 600 species of finfish found in the southern temperate zone, about 85% are found only in Australian waters.7 Conversely groups of animals and plants found in many other countries are not found naturally here. Hooved animals, cats, canids (foxes and Dingos) and plants like thistles, for example, have been introduced and affected native biodiversity.
Far less is known about the world of invertebrates and micro-organisms, though Australia has several hundred thousand such species, the majority of which have not been described.7 There remains much to be learnt about our biodiversity. In 2000, for example, scientists announced the discovery of a new type of antibiotic - as powerful as penicillin - in the eggs of an Australian shellfish.12
Presumed mammalian extinctions(a) since 1788
|Darling Downs Hopping Mouse|
|Big-eared Hopping Mouse|
|White-footed Rabbit Rat|
|Short-tailed Hopping Mouse|
|Long-tailed Hopping Mouse|
|Lesser Stick-nest Rat|
|Crescent Nailtail Wallaby|
|(a) Excludes subspecies and extinctions from Christmas and Lord Howe Islands.|
Source: A Gap in Nature 7 and Mammals of Australia13.
|Seventeen species of mammals (and another 10 subspecies) are listed by the Commonwealth as presumed extinct in mainland Australia since 1788. Ten of these species were last seen alive in the twentieth century, ten of these animals are marsupials, and 14 of them were found predominantly in the inland arid zone. However, other groups of animals have fared rather better, at least in terms of losses through extinction.|
Over the past 200 years many elements of Australia's biodiversity have declined, and species of mammals, birds, frogs and plants are presumed to have become extinct. Our mammals have been affected particularly severely: 17 of the 270 or so species of mammal that lived in continental Australia in 1788 are now presumed extinct, under the Environment Protection and Biodiversity Conservation Act 1999. Ten of these species were lost in the past 100 years.
The table above lists the mammal species (but not subspecies) that are believed to have become extinct in Australia since 1788. A further seven subspecies are presumed extinct, and several other species now survive on offshore islands or Tasmania but are extinct on the mainland. This compares with three extinct birds from about 700 species (another four subspecies have also become extinct), four extinct frogs from over 200 species, and 61 species of flowering plants from over 15,000 species. No freshwater fish or reptile species are known to have become extinct, though other species may have become extinct before they were ever recorded (and this is probably more likely for species of fish and plants than for birds and mammals because they are less well documented).
Some differences within Australia
The numbers of extinctions in different states and territories depend on many factors such as the types of ecosystems within a state, the level of human disturbance and the impact of exotic species. But among the states and territories, South Australia has lost more mammals than any other state: at least 28 species of mammal are presumed extinct from that state (though here, as in other states, some of these animals continue to survive elsewhere in Australia). New South Wales has also lost many species (26), and Victoria 21. The Northern Territory has lost an estimated 14 mammal species, Western Australia has lost ten and Queensland four. The Australian Capital Territory does not maintain a list of extinct mammals, although in recent times only one species is believed to have been lost (the Brush-tailed Rock Wallaby), while Tasmania is thought to have lost the Thylacine but no other mammal species since 1788.
As well as considering individual species, it is useful to consider entire ecosystems, which are the result of long-term interactions between the physical environment and living species. The area of land in conservation reserves is one possible indicator of the extent to which ecosystems are protected. This has been increasing and just over 10% of Australia's land was protected in areas such as national parks in 2002.14
Among the states and the territories, in 2002 the ACT had the largest proportion of land in conservation reserves (54%), followed by Tasmania (37%), South Australia (26%) and Victoria (15%). Only 4% of Queensland was in reserves along with 5% in the NT and 7% in New South Wales.14 There are many examples of specific change, for the better or worse, in every state. For example, fox control in Western Australia helped the numbers of several threatened marsupials to increase over the 1990s, while in 2001 the NSW Government declared six woodland bird species to be vulnerable, primarily because of habitat clearing and fragmentation.15 Many endangered species face more than one threat. The box overleaf looks in more detail at four of Australia's endangered animals, and discusses why they are assessed as threatened and what is being done to protect them.
About 70% of land clearance in 2001 occurred in Queensland where an estimated 171,000 ha were cleared. Western Australia cleared a further 32,000 ha and New South Wales cleared 24,000 ha. Clearance in the other states and territories ranged from about 1,000 to 10,000 ha. Estimated rates of clearance before 1990 are less accurate, although the NGI figures indicate that land clearance in Queensland was continually higher than in any other state between 1970 and 1990. Over a longer period, however, other states have cleared a greater proportion of their land than Queensland, which has cleared 18% of land compared to 30% in New South Wales and the Australian Capital Territory and 60% in Victoria.5
Factors influencing change
|Threatened species and their conservation Dibbler|
The Dibbler (Parantechinus apicalis) is a small carnivorous marsupial that weighs up to 120 grams. It was rediscovered after more than 80 years in 1967 at Cheyne Beach near Albany on the south coast of Western Australia. At the time of European settlement Dibblers ranged across the south-western corner of Australia but are now only found in a few scattered areas of heathland including the Fitzgerald River National Park ( east of Albany), and islands off Jurien Bay (north of Perth). Scientists believe that the clearing of land and spread of the fox are in part responsible for the Dibbler’s rarity. Dibblers have been bred at Perth Zoo since 1997 and have been successfully reintroduced to Escape Island, in Jurien Bay, which is free from foxes and cats. Captive-bred Dibblers are also being reintroduced to Peniup Nature Reserve, near WA’s south coast, where fox numbers are controlled through baiting. 16
Large-eared Horseshoe Bat
The Large-eared Horseshoe Bat (Rhinolophus philippinensis) is found in the rainforest and woodlands of eastern
Queensland north of Ingham. The bats, whose ears are about one third of the length of their 6 cm long body, usually roost in caves and mines but little is known about their habits. Scientists in Queensland are working to protect the species, and are focusing on the bats’ roost sites by gating off abandoned mines to allow the bats to enter and exit but prevent people from disturbing them and by building artificial caves for the bats to use. The North Queensland Mining Council are a member of the recovery team set up to protect the species and various mining and mineral organisations gave financial support to help produce a recovery plan and associated handbook about Australian bats and mines.17
Golden-shouldered Parrots (Psephotus chrysopterygius) are closely related to the extinct Paradise Parrot. Fewer than 2000 remain, all in far North Queensland. The birds live in tropical savanna woodland and nest in termite mounds. They feed on a range of grasses, which are in short supply early in the annual wet season. The shortage can be made worse by a lack of burning in the early wet season and intense cattle and pig grazing. Altered fire patterns and grazing have also resulted in an increase in the density of woody shrubs which, it is thought, make the parrots more vulnerable to predators. Although the species declined in parts of its range between 1992 and 1998, this contraction may now have stabilised. Local landholders are working with the government to control cattle grazing, provide supplementary food and to burn at appropriate times of year. Plans are underway to reintroduce them to parts of their former range.18
Northern Hairy-nosed Wombat
The Northern Hairy-nosed Wombat (Lasiorhinus krefftii) is one of the world’s rarest mammals. About 100 animals survive in 500 hectares of grassy woodland in Epping Forest National Park, central Queensland. The wombats, which typically weigh a little more than 30 kg, were more widespread at the end of the nineteenth century when populations lived in southern New South Wales and southern Queensland. But by the early twentieth century the last remaining population was at Epping Forest. Experts believe the wombat probably declined during times of severe drought when heavy grazing by cattle and sheep left little pasture for the wombats. The Queensland Parks and Wildlife Service are working with universities and other organisations to protect the species. In 2002 they built a dingo-proof fence around the wombat’s habitat after dingoes killed 10 animals in 2000 and 2001. A major recovery program aims to establish a second wild population within five years.19
Many factors threaten biodiversity. Species are often affected by more than one threat, and one threat can affect many species. Knowledge of ecosystems and their complex relationships is limited and a decline in one species can have important consequences elsewhere.
Change and disturbance are a natural part of every environment. But human activity almost invariably affects the direction and pace of change and the extent of disturbance, challenging the ability of ecosystems and species to respond.20 Over the past 200 years, change in Australia has, by world standards, been great and rapid, and has had a profound effect on our biodiversity. The change has taken many forms, including large scale land clearance and the introduction of many exotic species, while the use of water, primarily for agriculture, has damaged the health of freshwater ecosystems.
The changes since 1788 have had far-reaching effects on biodiversity. Species interact with one another and their environment in a complicated web of checks and balances that has developed over millions of years.
A change to one part of the system can have important, sometimes unforeseen consequences elsewhere through a cascade of effects. The removal of native vegetation is an example: clearing plants removes the food that herbivores rely on, and consequently impacts on the carnivores higher up the food chain. Removal of plants can lead to soil erosion or the loss of soil nutrients: both processes reduce the biodiversity present among the vast array of minute species that live in the soil. And as a patchwork of vegetation is cleared, the remaining islands of native vegetation can be more vulnerable to damage from threats such as weed invasions, while the animals left within these islands may be isolated and so more vulnerable to events such as the bushfires in south-east Australia in 2002.
The NLWRA concluded that vegetation clearing is the most significant threat to species and ecosystems in eastern Australia. Overgrazing, exotic weeds, feral animals and changed fire regimes are additional key threats across the country. And fragmentation of remnant native vegetation, increased salinity and firewood collection are threats to biodiversity in the highly modified regions of southern and eastern Australia.8
Together with land clearing, the Commonwealth list of key threats to biodiversity includes a number of invasive species such as: foxes and cats (which prey on native species); rabbits, pigs and goats (which compete for and degrade land); and dieback fungus (which is damaging whole forests). Other important threats identified include: water use, salinity, climate change, pollutants, and fishing.
Although Australia’s biodiversity continues to be threatened by many factors, much is being done to protect our flora and fauna. Governments, non-governmental organisations, the private sector and local communities all play a part. Conservation is promoted in many ways including legislation, the mitigation of threatening processes (such as fox and weed control), land rehabilitation, scientific research and education. And the comprehensiveness of the nation’s system of conservation reserves improved in the 1990s.1
The state and territory parks and wildlife services are working to conserve native flora and fauna, and in some areas endangered species are being reintroduced to areas where they were formerly present. Bridled Nailtail Wallabies and Yellow-footed Rock Wallabies have been reintroduced, for instance, to Idalia National Park in central Queensland. Operation Western Shield in Western Australia has significantly reduced fox numbers in parts of the State, and marsupials like the Numbat, Woylie (or Brush-tailed Bettong ) and Chudditch (or Western Quoll) have increased in numbers. Other states and the territories are working on similar schemes, while nationally, urban conservation initiatives are involving more Australians in projects focused close to where they live and work. The recent Bush Forever initiative by the Western Australian Government is a good example: it identified regionally significant urban bushland to be retained and protected.1 The area of land in protected reserves has increased over the past decade. Species recovery plans and threat abatement plans are also addressing many issues, though it is too early in some cases to gauge their effectiveness.
About 63% of Australia is held in private hands, either freehold or leasehold, and is managed for commercial use, and so private landowners can play a significant part in helping to conserve biodiversity.21 Indigenous Australians’ role in land management is increasingly recognised as important. Indigenous Australians manage around 15% of the country and they have an extensive understanding of Australian ecology from which others are learning.
Some industries are also beginning to show greater concern for protecting biodiversity. The mining industry, for example, has developed codes of practice for environmental management, and is employing biologists to help assess and minimise the impacts of mining operations.
The Natural Heritage Trust was set up by the Australian Government in 1997 to help restore and conserve our natural resources. It is the largest environmental rescue plan undertaken in Australia, and is expected to have spent $2.7 billion by 2007. Thousands of community groups have received funding for environmental projects.22 Meanwhile other work, such as the National Action Plan for Salinity and Water Quality is underway to address Australia’s natural resources, and some of these initiatives are discussed elsewhere in the Natural landscape commentary.
Protecting Australia’s land
While the pressures to clear land remain, Australians are responding to protect bushland. Ideally one would consider the total area of land that is being managed by government, organisations and individuals to conserve biodiversity. But current information on the area of all such land is not available. But there are recent data on the area of land protected inside conservation reserves. This is growing, and, in 2002, over 77 million ha (just over 10% of Australia) were in protected areas. This is an increase of about 17 million ha since 1997. Some ecosystems are protected better than others: the chart shows that, in 2002, 17 of Australia’s 85 major biogeographic regions (IBRAs) had less than 2% of their area (down from 24 IBRAs in 1997) protected; four of these regions had less than 1% of their area protected (down from 12 IBRAs in 1997) and one region had no area at all within the reserve system (down from two IBRAs in 1997).14 Legislation, such as the native vegetation acts enacted in Queensland, New South Wales and South Australia in the 1990s, targeted at controlling the clearing of native vegetation are now in force.
A little less than two-thirds of Australian land is privately owned.21 Efforts to protect biodiversity now extend beyond the reserve system into some of this private land. In 2003, for instance, there are about 4,500 community landcare groups,23 while across Australia in the late 1990s more than 1,300 conservation covenants - made between private landholders and governments - helped protect 774,000 ha of mostly private land.24 Some companies and community groups also operate conservation reserves: Birds Australia for instance now has two reserves (Gluepot and Newhaven) with a combined area of over 300,000 ha.
Proportion of ecosystems(a), area protected
Australian governments have encouraged land clearance through most of our agricultural history. Some land purchase agreements required it, taxation incentives encouraged it and agricultural departments provided advice on how to do it. But by the mid-1980s concern about the rate of loss of native vegetation had grown and governments began to establish controls on clearance.
Indeed, the Queensland and Australian governments have worked together to address land clearing in that State. And in March 2004, the Queensland Government introduced legislation to their parliament intended to phase out broadscale clearing of remnant vegetation by the end of 2006.
Area under crops - 1902 to 2002
|In 2002 about 24 million ha of land were being used to grow crops and a similar area was improved pasture. These areas together represent around 10% of Australia’s agricultural land and about 6% of all Australia. Between March 1992 and June 2002 the area of land used for crops increased by about 50% from 16,400 ha in 1992, although the total area of agricultural land holdings declined slightly. This reflects the intensification, rather than spread, of agriculture over the period.|
Although the growth of cities and towns has only affected land cover over a small area (less than 0.1%),25 it can have regional effects. Most of the urbanisation has occurred around the coast, sometimes in regions of high biodiversity, while future housing development in some areas may entail clearing threatened (now remnant) woodland communities such as the Cumberland Woodland around Sydney.26
However, agriculture has been responsible for the majority of land clearance in Australia. Although about 60% (460 million hectares) of Australia is used for agriculture, clearing has been selective, with the vegetation occupying the better soil and gentler slopes cleared first. For example, 79% of the Victorian south-east coastal plain has been cleared.5 The most intensive agricultural land clearance has occurred in areas where crops or sown pasture have been planted.
Links to other dimensions of progress
Some of the threats to biodiversity are discussed elsewhere in this publication. Headline indicators of soil degradation, inland waters, air quality and greenhouse gases each relate to areas of concern that affect our plants and animals as well as other aspects of progress. Invasive species, marine ecosystems and land use are also discussed. Another factor, discussed in the box above, is changes to the patterns of fire.
Wildlife is important to many Australians - aesthetically, recreationally and culturally, particularly for many Indigenous Australians.
|Fire and biodiversity|
There is a growing awareness of the links between fire regimes (the season, frequency, intensity and type of fires) and conservation of biodiversity. In northern Australia in particular, many animals depend on a certain pattern of fires for survival.
Experts think that fires have tended to be less frequent since European settlement than they were when Indigenous Australians managed the land. However, these less frequent fires have had more fuel to power them, and they have been more intense and, in some areas, more destructive as a result. In other parts of Australia, by contrast, experts believe that a higher frequency of low intensity fires can be more damaging to biodiversity than less frequent high intensity fires. Different fire regimes impact differently on different species, and scientists are only beginning to understand the importance and complexity of planning and implementing fire regimes.27
Biodiversity brings income and employment to Australia, through tourism for example (in 1995 half of international visitors went to a national park)28, while agriculture relies on a variety of services provided by biodiversity to keep soil healthy, water clean and crops pollinated. But economic activity - including land clearance for agriculture and flow-on effects like salinity - has been a major reason for the decline of many species. Invasive species have also played a role.
The vast majority of land that has been cleared has been used in economic production, in particular agriculture, which has generated income and employment. But land clearance has economic impacts too. It can, for instance, lead to costs associated with reduced flood control, the provision of potable water or increased salinity and soil erosion.
About 7% of Australia's total greenhouse emissions are estimated to arise from land clearance (greenhouse gases are released from the burning and decay of vegetation and from the disturbance of soil which releases carbon). Clearing vegetation plays an important role in the spread of invasive species, land degradation and declining water quality (which are important to the environment and can impose costs upon the economy).
See also the commentaries National income, Work, The natural landscape - invasive species, The natural landscape - water, The natural landscape - land, and International environmental concerns.
The natural landscape - invasive species
1 State of the Environment Committee 2002, Australia - State of the Environment Report 2001, CSIRO Publishing, Melbourne.
2 The Wilderness Society 1999, Australia's Biodiversity - A Summary. <http://www.wilderness.org.au /campaigns /policy/biodivsum/> last viewed 23 March 2004.
3 Saunders, D., Margules, C. and Hill, B. 1998, Environmental Indicators for National State of the Environment Reporting - Biodiversity, Department of the Environment, Canberra.
4 National Land and Water Resources Audit 2001, Australian Native Vegetation Assessment 2001, National Land and Water Resources Audit, Canberra.
5 Department of the Environment, Sport and Territories 1996, National Strategy for the Conservation of Australia's Biological Diversity, DEST, Canberra.
6 State of the Environment Advisory Council 1996, Australia - State of the Environment Report 1996, CSIRO Publishing, Melbourne.
7 Based on information in Flannery, T. and Schouten, P. 2001, A Gap in Nature, Text Publishing, Melbourne; and data from the Committee for Recently Extinct Organisms, <www.crea.amnh.org> last viewed 22 February 2002.
8 The National Land and Water Resources Audit 2002, Australian Terrestrial Biodiversity Assessment 2002, National Land and Water Resources Audit, Canberra.
9 Australian National Botanic Gardens 1998, Australian Flora & Vegetation Statistics, <http://www.anbg.gov.au/anbg/australian-flora-statistics.html> last viewed 23 March 2004.
10 IUCN Species Survival Commission News Release 12.0701, 'SSC expertise called on for strategy to save Europe's plants', IUCN, Switzerland, <http// www.iucn.org/themes/ssc/news/plantstrategy.html> last viewed 23 March 2004.
11 Conservation International 1998, electronically published on the Internet in 1998 <http:// www.organisation.org/web/fieldact/megadiv/ megadiv/htm>.
12 Benkendorff, K., Bremner, J.B. and Davis, A.R. 2000, 'A putative role for the precursors of Tyrian Purple in the egg masses of the Australian Muricid, Dicathais orbita', Journal of Chemical Ecology, 26.
13 Strahan, R. 1995, The Mammals of Australia, Reed Books, Chatswood, NSW.
14 Department of the Environment and Heritage. 2004, Collaborative Australian Protected Area Database 2002, Environment Australia,Canberra.<http://www.deh.gov.au/parks/nrs/capad/index.html> last viewed 1 February 2004.
15 In October 2001 the NSW scientific committee determined the following six woodland species as vulnerable: Grey Crowned Babbler (eastern form), Hooded Robin (south-eastern form), Brown Treecreeper (eastern form), Black-chinned Honeyeater (eastern form), Speckled Warbler and Diamond Firetail. <http://www.npws.nsw.gov.au/ news/tscdets/index.html> last viewed 23 March 2004.
16 Dr. Tony Friend, Western Australian Department of Conservation and Land Management, personal communication.
17 Thomson, B. 2002, Australian Handbook for the Conservation of Bats in Mines and Artificial Cave-Bat Habitats, Australian Centre for Mining Environmental Research.
18 Dr. Stephen Garnett, Queensland Environmental Protection Agency, personal communication.
19 Dr. Alan Horsup, Queensland Environmental Protection Agency, personal communication.
20 Saunders, D., Hopkins, A., and How, R. 1990, 'Australian Ecosystems: 200 Years of utilization, degradation and reconstruction', in Proceedings of the Ecological Society of Australia, 16, ESA, Canberra.
21 AUSLIG (Australian Land Survey Information Group) 1993, Land Tenure Map.<http://www.auslig.gov.au/ facts/tenure/index.htm> last viewed 23 March 2004.
22 For more information about the Natural Heritage Trust see <http://www.nht.gov.au> last viewed 1 March 2004.
23 Landcare Australia 2004, Landcare Groups <www.landcareaustralia.com.au/groups.asp> last viewed 19 March 2004.
24 Binning, C. and Young, M. 1999, Talking to the Taxman about Nature Conservation, Research Report 4/99, Environment Australia, Canberra.
25 Barson, M., Randall, L. and Bordas, V. 2000, Land cover changes in Australia. Results of the Collaborative Bureau of Rural Sciences-State Agencies Project on Remote Sensing of Land Cover Change, Bureau of Rural Sciences, Canberra.
26 National Parks and Wildlife Service NSW 2001, Endangered Ecological Community Information: Cumberland Plain woodland, National Parks and Wildlife Service NSW. <www.npws.gov.au/wildlife/thr_profiles/Cumberland%20Plain%20 Woodland.pdf> last viewed 18 February 2002.
27 Gill, A.M, Groves, R.H. and Noble I.R. (eds) 1981, Fire and the Australian Biota, Australian Academy of Science, Canberra.
28 Blamey, R. and Hatch, D. 1998, Profiles and Motivations of Nature-based Tourists Visiting Australia, Bureau of Tourism Research Occasional Paper No.2, BTR, Canberra.
It is difficult to conceive of a single indicator that could measure the impact of invasive species on Australia, because of the difficulty in measuring their environmental and financial cost. Few national data are available on the impact that many of the thousands of invasive species have had. Although it is difficult to assess change in this area, invasive species have had an important impact on aspects of Australian progress. This commentary discusses some of those species, together with the ways in which they have become established and what is being done to control them.
|An invasive species can be defined as a species occurring as a result of human activities (deliberate or accidental) outside its accepted normal distribution, which threatens valued environmental, agricultural or personal resources by the damage it causes. Invasive species include both foreign and native plants and animals (although not all such animals threaten valuable resources, and so not all are necessarily invasive).|
The introduction of invasive species is a continual process, and they are an environmental, social and economic problem. Invasive species occur in all habitats, and many invasive plants and animals are increasing in number and spreading across Australia. They exert a major pressure on biodiversity, and can degrade the land and harm water quality.
The Australian continent's long isolation from the rest of the world has endowed us with a unique set of plants and animals. Like other islands, our isolation has also made our flora and fauna susceptible to the impact of invasive species: native species have not had prior exposure to organisms like many of those that have arrived from overseas. Some invasive species thrive in Australia because the predators and parasites that controlled them at home do not exist here, while some species grow more quickly, breed more prolifically or have more varied diets than their Australian counterparts. Environmental disturbance, particularly clearing and modification of native vegetation and habitat fragmentation, is widely thought to help many invasive species to establish and spread.1
Many of Australia's most serious animal pests (invasive animals) were introduced deliberately, and species are still being introduced, deliberately and accidentally. The foxes, first sighted in Tasmania in early 2002, the establishment of fire ants in Brisbane (now apparently under control), and the discovery of several species of exotic ants in the Northern Territory are new concerns. Estimates published in 2002, said that 30 of the more serious animal pest species cost the economy at least $420m a year (mainly in lost agricultural production).1
A plant which has, or has potential to have, a detrimental effect on economic, conservation or social values, is considered to be a weed.2 In other words it is a plant growing in the wrong place. Weeds (invasive plants) alone were estimated to have cost the Australian economy $3.3b each year in lost agricultural production and control costs during the early 1990s,2 while the cost to the wider environment is virtually unknown.
Species-threatening invasive animals, number of species threatened(a)
|Birds and mammals threatened by Invasive species |
The Environment Protection and Biodiversity Conservation Act 1999 lists processes which threaten native species. This list of key threatening processes includes a number of invasive animals. The graph shows the number of bird and mammal species listed as threatened by these invasive animals (some native species are threatened by more than one invasive animal). In 2004, cats were listed as threatening 25 mammals and 10 bird species with extinction, while foxes threatened 21 mammals and seven bird species.
In 2004, 26 mammals, 20 birds, four reptiles, one amphibian and at least 23 freshwater fish species introduced from overseas were established in Australia,1,3 along with about 2,000 plants.4 The abundance and range of a number of native animals and plants have also changed because of human activity. Not all of these species are invasive or widespread now, but many have the potential to become invasive.
Some invasive species from overseas
Introduced predators like the fox and cat have spread over much of Australia and have contributed to the decline or extinction of some native species, through predation or the spread of disease. Cane Toads have advanced through Queensland to Cape York, south to Port Macquarie and into the Northern Territory, and have reached Kakadu. They eat mainly insects, but also frogs, small mammals and snakes. And because they are poisonous, they kill many animals that prey on them such as goannas, quolls (tiger cats);1 and some birds (although certain birds are learning to kill the toads and eat their organs while avoiding the poisonous glands).5
Rabbits have at times reached plague proportions over much of Australia, competing with native animals for resources, overgrazing vegetation and digging holes which damage soil structure.
Goats strip vegetation, erode slopes and compete with rock wallabies for food and shelter. Donkeys and pigs cause erosion and spread weeds (pigs also eat rare plant species).Commercial honeybees are an invasive insect, found in nearly every habitat.6 They compete for nectar with native insects as well as birds and mammals from which they also take nestholes.
Exotic mammal species established in the wild and bioregions affected, 2002
No. of bioregions
|Five Striped Palm Squirrel|
|Source: The National Land and Water Resources Audit, Australian Terrestrial Biodiversity Assessment 2002.|
All states and territories have populations of fish introduced from overseas. Thirty-five exotic fish species have become established in inland waters, with eight identified as having a significant effect. Many exotic fish species continue to increase in range and abundance. Programs to eradicate exotic fish species are being attempted in some areas.7 And exotic marine animals (often introduced into coastal waters from ships' ballast or riding on hulls), have entered and disrupted native food chains, and can dominate local communities.
|At least 26 exotic mammal species were established in Australia at the start of 2002. Some, like the House Mouse, Cat and Dingo are found throughout the country’s 76 mainland bioregions. Others, like the Polecat and Polynesian Rat have a much more localised distribution but have a high risk of increasing their range to the detriment of indigenous wildlife.|
Other introduced organisms, such as dieback fungus (Phytophthera cinnamomi), invade plant communities, killing selected species, and disrupting ecological processes. Dieback is the most important threat to the biodiversity of the Stirling Range National Park in Western Australia. Some plants (such as banksias and grevilleas) are highly susceptible, and 80% to 100% of infected individuals may die. The exposed ground is often invaded by weeds.8
Native species which are invasive
Outside their natural range or in increased numbers, native species may be as serious a threat to biodiversity as exotic ones. Many are spreading and increasing in abundance because of recent human activity. Plant species native to one part of Australia have been introduced to other parts where they have become invasive. For example, the Sweet Pittosporum, a rainforest tree from south-east Australia, now grows wild in Western Australia, South Australia and western Victoria, invading open woodlands and shading out rare plants.6
Large areas of grass and crops, together with more watering points, have encouraged Galahs, for example, to expand their range and colonise much of Australia. Galahs compete for nest sites with birds native to the area, like Carnaby's Cockatoo, an endangered black cockatoo from south-west Western Australia.8
Weeds - invasive plants
The National Weeds Strategy states that weeds are among the most serious threats to Australia's primary production and natural environment, and are increasingly moving into or towards almost all ecosystems of immediate economic, social or conservation value.2 They displace native species, and the effects flow on to animals, such as insects and birds, that rely on native plants for food and shelter. Many weeds also interfere with agricultural production.
About 350 weed species in Australia have been declared noxious.9 To help focus national efforts addressing the weed problem, a 'Top 20' list of 'Weeds of National Significance' has been compiled.
Weeds of national significance, distribution - 1999
Weeds also cause environmental damage that is difficult to quantify. Some species cover very large areas. Blackberry ranges over 9% of Australia. Weeds also affect important conservation regions. Mimosa, which threatens the Kakadu World Heritage Area, can grow to a height of six metres, and produces so many seeds that it can double in area every year, turning species-rich tropical wetlands of northern Australia into a Mimosa monoculture.11 These weeds, and many more, pose a serious threat to biodiversity.
So-called sleeper weeds (weeds that are established or newly arrived but are not as yet a widespread problem) are now recognised to be of major concern.7 For years Athel Pine did not pose a problem until the wet year of 1974, when thousands of seedlings, washed from homestead gardens, sprouted along inland waterways.6 It now grows along water courses in central Australia, changing the river flow, displacing red gums and raising water tables thereby contributing to salinity.8
Distribution in 1999
|Common name||Origin of weed|
|Athel pine||North Africa, Arabia, Iran and India|
|Bitou bush/Boneseed||South Africa|
|Bridal creeper||South Africa|
|Cabomba||United States of America|
|Chilean needle grass||South America|
|Pond apple||The Americas and west Africa|
|Prickly acacia||Africa and Asia|
|Serrated tussock||South America|
|Willows||Europe, America and Asia|
|Source: Weeds Australia 1999;2 Thorp and Lynch 2000.10|
Weeds also cause flow-on effects. Some weeds are either more flammable or more fire retardant than the species they displace, and can alter the fire patterns of the communities they invade (which may have effects on native animals living in those communities). Other weeds provide food and shelter for invasive animals.
A history of introductions
Despite Australia's isolation, over millions of years species have arrived naturally from elsewhere in the world. Birds have flown here, and seeds have been carried by ocean currents or blown by the wind. But since European colonisation, the rate of invasion has changed: thousands of foreign animals, plants, insects and fungi have arrived and become established since 1788, compared to an estimated rate before that of one or two species per millennium.6
Exotic mammals have existed in Australia for a long time. Dingos, which were bred from wolves in Asia, first arrived in Australia some 4,000 years ago, probably brought here by people from Indonesia.6 Experts are still debating whether cats arrived in Australia before Europeans.
However, the vast majority of foreign species have arrived since European colonisation. Many were introduced deliberately. Early settlers brought species like pigs and blackberries with them. They released the animals into the wild and sowed seeds as they travelled to provide a source of food for those who followed them. Rabbits and foxes were introduced to be hunted for sport. And the 'acclimatisation societies' of the nineteenth century introduced animals which became pests, like sparrows, starlings and carp, to enrich Australia's native fauna.
Controlling invasive species
The problems caused by invasive organisms are widely recognised and work is being done to combat them. Effort for invasive plants is being focused through the National Weeds Strategy, which was released for the first time in 1997 and updated in 1999. It lists 20 weeds of national significance and another 28 species that pose a potential threat to biodiversity. Threat abatement plans have also been developed for the fox, rabbit, cat and goat to combat their threat to endangered native species. And a threat abatement plan for dieback fungus was adopted in late 2001 to assist in addressing this major threat to biodiversity.12
The Australian Quarantine and Inspection Service (AQIS) continues to develop new ways to prevent potentially invasive species from entering this country. For instance, it is working closely with Torres Strait Islanders to reduce the risks of invasive species entering the country across the Torres Strait, while AQIS scientists monitor our northern shores searching for new introductions. AQIS officers also work overseas helping neighbouring countries to control species before they spread to Australia.
Biological control, which involves introducing parasites, predators or diseases, can reduce populations of invasive species. Myxomatosis and calicivirus have helped reduce rabbit numbers in many parts of Australia. And in 1994, 16 Dingos were released onto Townshend Island, central Queensland to control goats. By 1996 all but four of the island's 1,700 goats had died.6 However, while biological control can be very effective (such as against prickly pear in the 1930s) it can also fail. When used against weeds for example, it failed to produce significant benefits more than three-quarters of the time.2 Worse than simply not working, the new control species could potentially become a pest species itself, as happened with the Cane Toad: all introductions are now handled more carefully and extensively researched before they are released.
It is often difficult to use poisons or herbicides to control invasive species without harming native species as well: poison baits, for example, used to kill cats or foxes, can easily be eaten by native wildlife. But certain poisons can be effective in targeting the right animals. Some native animals have evolved an immunity to a poison called 1080 which is found in native plants of the genus Gastrolobium in south-west Western Australia. This poison has been successful in significantly reducing fox numbers in parts of Australia, although native animals in some places (especially areas far from south-west Western Australia) have little or no immunity to the poison and can also be affected.
Some of our native species are beginning to adapt to life with invasive plants and animals. Wedge-tailed Eagles and other raptors feed frequently on rabbits in parts of Australia, while house mice are an important part of the diet of Barn Owls in parts of the country. Some endangered birds and mammals are beginning to depend on weeds for shelter (such as the Black-Breasted Button Quail which now live in lantana thickets).6 Trout were introduced as game fish, and an American minnow, commonly known as the Mosquito Fish, was introduced in the hope it would eat mosquito larvae and rid our cities of mosquitoes.
Some endangered birds and mammals are beginning to depend on weeds for shelter (such as the Black-Breasted Button Quail which now live in lantana thickets).6 Trout were introduced as game fish, and an American minnow, commonly known as the Mosquito Fish, was introduced in the hope it would eat mosquito larvae and rid our cities of mosquitoes.
The Cane Toad was introduced in the 1930s to help sugar cane farmers to control a native beetle that was eating their crop. The toad had little effect on the beetle, but it has had a very significant impact on many native species. And research agencies have introduced many foreign grasses as pasture, some of which have become major weeds.
Research agencies and pastoralists continue to introduce foreign grasses and legumes in an attempt to make rangelands more profitable. Between 1947 and 1996, for example, over 460 exotic plant species were introduced as pasture. Only 5% of these have proved useful as fodder, yet 13% have become major weeds, including Para Grass, which has spread into Kakadu National Park, reducing habitat for water birds.8
The Department of Agriculture, Fisheries and Forestry has set up a risk assessment process for invasive species. This assesses the potential invasiveness of species that people want to bring into Australia, to try to prevent the importation of further invasive species.13
However, nurseries and garden centres still sell many species of recognised weeds, and garden plants comprise many of the top 20 worst weeds and are the main management problem in some national parks.6 For example, Rubber Vine from Madagascar now smothers large areas of woodland and forest (its current distribution is some 600,000 km2, but it could potentially spread over five times that area).10
The pet trade imports millions of live fish each year, some of which carry diseases that can infect native species. Exotic aquarium fish, plants and snails have entered our waterways, sometimes after owners have dumped them, or when ponds overflowed. Two of the top 20 worst weeds, Cabomba and Salvinia, are aquarium plants.6
Australia's growing trade links with the rest of the world provide a threat. Because Australia exports so many bulk commodities, we are a net importer of water carried as ballast by ships, water which has originated in other parts of the world and carries foreign plants and animals. Some, like the Northern Pacific Seastar, which eats oysters, mussels and other sedentary species, are having a major impact on our waters.7 Ships also carry barnacles from around the world, while insects, spiders and reptiles arrive in cargo crates.
International travellers can carry foreign seeds on their clothing, and those travelling within Australia move native and non-native species around on their cars, while diseases such as Dieback Fungus have invaded reserves on road building machines.6 And exotic diseases, such as the virus which killed very large numbers of pilchards in our southern waters during the mid-1990s, are difficult to detect and can enter the country in a variety of ways.6
|New threats |
Foxes in Tasmania
In early 2002 there was evidence that the fox was becoming established in hitherto fox-free Tasmania, after illegal introductions. If established the fox could threaten the survival of several animals that are either extinct or endangered elsewhere in Australia. In February 2002, the Tasmanian Parks and Wildlife Service estimated that up to 20 foxes might be living on the island and a campaign was underway to remove them.14
Between January 2002 and January 2004, the Fox Taskforce received over 650 reports of fox sightings, more than 100 of which were classed as ‘highly credible’. Fox footprints and scats have been found, a fox was shot and another was hit by a vehicle near Burnie. In July 2003 the Fox Taskforce began a large baiting program around fox ‘hotspots’; in the north, north-west and south of the island. Around 13,000 fox baits were laid by December 2003, effectively covering about 260,000 hectares of Tasmania.
A reduction in evidence and sightings from areas that have had repeat baiting programs in late 2002 and 2003 has been seen. Baiting is expected to recommence in April 2004.15
Fire Ants were recorded in Australia for the first time in February 2001 when they were found in Brisbane. By February 2002 the ants had been found on several hundred properties around Brisbane. Because the ants can be transported in soil or machinery, a national eradication program is trying to destroy them before they become more widely established.
These ants, which have been described as the greatest ecological threat to Australia since the rabbit, could potentially spread to most of the major coastal cities and throughout the tropical north. The ants are aggressive and will feed on small ground fauna including insects, frogs, lizards, birds and mammals. They usually nest on the ground, but often infest (and so damage) electrical equipment (causing fires) and machinery. In the United States of America (where fire ants are an invasive species), the Federal Department of Agriculture reports that the ants attack and sometimes kill newborn domestic animals, destroy crops, and damage and sometimes kill young citrus trees. Their painful bites give people blisters.
By June 2003, 650 people from the Queensland Department of Primary Industries were working on Fire Ant eradication and the species seemed to be under control, with 98% of affected properties in South East Queensland now Fire Ant-free, although people were still being asked to remain alert.16
At the end of 2003 nine species of exotic ants were discovered in the Tiwi Islands off the coast of northern Australia in significant numbers. Although the ants have been living in Australia for the past hundred years their populations have recently reached a size at which they are starting to spread rapidly. The ants, which cause problems similar to Fire Ants (see above), present a significant social, economic and environmental threat to the Aboriginal communities living in the affected areas. Three species - the African Big-Headed Ant, the Ginger Ant and the Singapore Ant - are causing particular concern. Meanwhile another species, the Yellow Crazy Ant had invaded north east Arnhem Land, and had the potential to spread to Broome. CSIRO are working with the Northern Land Council and Tiwi Land Council to control the pests.17
Links to other dimensions of progress
Invasive species have had significant impacts on Australian biodiversity. Weeds have affected agricultural productivity, have contributed to salinity and have affected the quality of our freshwater ecosystems. As the health of those ecosystems has declined, some foreign fish have been able to out-compete native species. Animals such as rabbits, pigs and goats have caused erosion and grazed heavily on native vegetation.
Many invasive species appear to do best in a disturbed environment, and land clearance is recognised as helping many invaders to spread. Gardeners and agriculture have also been responsible for the introduction of many invasive species from overseas.
See also the commentaries The natural landscape - biodiversity, The natural Landscape - inland waters, Oceans and estuaries, National income, and Competitiveness and openness.
The natural landscape - land
Progress and the headline indicator
1 Bomford, M. and Hart, Q. 2002, 'Non-indigenous vertebrates in Australia', in Environmental and Economic Costs of Alien Plant, Animal and Microbe Invasion, CRC Press, New York (in press).
2 Weeds Australia 1999, The National Weeds Strategy: A Strategic Approach to Weed Problems of National Significance, <http://www.weeds.org.au> last viewed 23 March 2004.
3 The National Land and Water Resources Audit 2002, Australian Terrestrial Biodiversity Assessment 2002, National Land and Water Resources Audit, Canberra.
4 Australian National Botanic Gardens 1998, Australian Flora & Vegetation Statistics <http://www.anbg.gov.au/anbg/australian-flora-statistics.html> last viewed 23 March 2004.
5 Frog Decline Reversal Project 2002, The Unwanted Amphibian <www.fdrproject.org/pages/Toads.htm> last viewed 23 March 2004.
6 Low, T. 2000, Feral Future, Viking Books, Ringwood.
7 State of the Environment Advisory Council (SoE) 2002, Australia - State of the Environment Report 2001, State of the Environment Advisory Council, CSIRO Publishing, Melbourne.
8 State of the Environment Advisory Council (SoE) 1996, Australia - State of the Environment Report 1996, State of the Environment Advisory Council, CSIRO Publishing, Melbourne.
9 Weeds Australia 2004, Noxious Weed List <http://www.weeds.org.au/cgi-bin/weednet.cgi> last viewed 8 March 2004.
10 Thorp, J. and Lynch. R. 2000, The Determination of Weeds of National Significance, Natural Heritage Trust/National Weeds Strategy Executive Committee, Launceston.
11 Lonsdale, M. 1999, 'Weeding out the enemy', Ecos July-September 1999, pp. 32-37.
12 Environment Australia 2001, Threat Abatement Plan for Dieback caused by the root-rot fungus, Environment Australia <http://www.deh.gov.au/biodiversity/threatened/tap/phytophthora/> last viewed 23 March 2004.
13 AFFA 2002, The Weed Risk Assessment System Agriculture Fisheries and Forestry~Australia <http://www.affa.gov.au> last viewed 22 February 2002.
14 Tasmanian Parks and Wildlife, Fox Sightings, Tasmanian Department of Primary Industries, Water and Environment, Hobart.
<www.dpiwe.tas.gov.au/inter.nsf/WebPages/SJON-56P2RG?open> last viewed 23 March 2004.
15 Chris Emms, Tasmanian Department of Primary Industries, Water and Environment, personal communication.
16 Queensland Department of Primary Industries 2004, Fire ants - General information about fire ants, Queensland DPI <www.dpi.qld.gov.au/fireants/8061> last viewed 15 January 2004.
17 Commonwealth Scientific & Industrial Research Organisation 2003, Exotic ants threaten Aboriginal communities <http://www.csiro.au/index.asp?type=mediaRelease&id=Prants> last viewed 29 January 2004.
Our soil resources are an important natural asset, and their degradation is a significant concern to Australian farmers, governments and the general public. When left untreated, degraded soil reduces agricultural productivity, while salinity can damage buildings and infrastructure such as water pipes, roads and sewers. Degradation can also damage habitat for wildlife, kill micro-organisms that live in the soil, and harm the quality of our inland waters.
There are several forms of soil degradation in Australia. The natural acidity and salinity of some of our soils have been exacerbated by the way we use the land. Soil is eroded by wind and water or can be compacted. Ideally, the headline indicator would measure the land area affected by different types of degradation, and perhaps place a dollar value on the cost of degradation to agriculture, infrastructure and the environment. It might also measure whether the ways we use the land that lead to degradation are continuing. But many forms of degradation overlap one another, and there is no single measure of the area of degraded land in Australia. Moreover, some of these concerns (such as acidity) predominantly affect farm profits and so are primarily a financial concern to one part of the economy, rather than a key influence on the natural landscape.1
We focus here on dryland salinity, the impacts of which are wider than lost agricultural production and include damage to water resources, biodiversity, pipelines, houses and roads.2 Dryland salinity is a widespread form of soil degradation. It is linked to other forms of degradation such as soil erosion, is expensive to rectify and adversely affects agricultural or pastoral yields on about 3.3 million ha,2 compared to 5.7 million ha judged to have a high potential to develop salinity.2
Some of the practices that have led to salinity have raised agricultural production and brought economic benefits. But, once established, salinity can have adverse effects on agriculture. The cost to agricultural productivity from salinity, estimated at $187m in 2000, is less than the cost of some other forms of degradation such as acidity, estimated at over $1b in 2000. But the cost of salinity goes further.1 Salinity harms flora and fauna (primarily through loss of habitat), while saline water damages bitumen and concrete.2 In 2000 some 1,600 km of rail, 19,900 km of roads and 68 towns were at risk of damage from salinity.
By 2050 some 5,100 km of roads, 67,400 km of rail and 219 towns are predicted to be at risk. About 11,800 km of streams and lake perimeters are at risk now, a figure predicted to rise to 41,300 km by 2050.2 The 2002 ABS Survey of Salinity on Australian Farms found that about 20,000 farms and 2 million ha of agricultural land (rather than all land as reported by the NLWRA) showed signs of salinity. Some 800,000 ha of this land could not be used for agricultural production.3
Australia's soils are old and shallow, and are susceptible to degradation by agricultural activities. Salinity occurs when the water table rises, bringing natural salts to the surface (in sufficient quantity, these salts are toxic to most plants). When trees or other deep-rooted vegetation are replaced with vegetation that uses less water, the water table may rise to cause dryland salinity. (If the water table rises through increased irrigation then irrigation salinity can occur. While irrigation salinity is well understood and managed, dryland salinity is more difficult to remedy.2)
Analysts often discuss the on- and off-farm costs of degradation. The NLWRA estimates lost yield from dryland salinity to be about $190m in 2000. Off-farm costs are much more difficult to estimate, but the NLWRA suggests that by 2020 the annual costs of salinity arising from damaged infrastructure and declining water quality might amount to some $700m, without attempting to take account of any costs associated with damage to biodiversity.1
Impacts of salinity
For many farms affected, dryland salinity has meant loss of productivity and income. There are many off-farm impacts, the most significant of which appears to be the salinisation of rivers, which affects drinking and irrigation water (e.g. in Western Australia some surface water is already too saline for domestic use).1
Rising groundwater levels and the salt contained in the water damage road pavement, bitumen and concrete, while pipelines and other structures can also be affected. Wagga Wagga is one of the worst affected towns in New South Wales, where salinity is damaging roads, footpaths, parks, sewerage pipes, housing and industry. Other provincial towns in New South Wales and Victoria (such as Dubbo and Bendigo), as well as western Sydney, are also affected. Predictions suggest that about 30 rural towns in Western Australia will be threatened by rising water tables by 2050.2
Dryland salinity also threatens biodiversity, through loss of habitat on land and in water. Areas near water are often worst affected because they occupy the lowest parts of the landscape where saline groundwater first reaches the surface. Areas of remnant and rehabilitated native vegetation are under threat in Western Australia, South Australia, New South Wales and Victoria.2
Australia’s responses to salinity
Salinity is difficult to slow, halt or reverse.2 In southern Australia key responses include improving the water balance (through farming techniques or revegetation), draining or intercepting and evaporating salty groundwater, or living with salinity and implementing saline agriculture and aquaculture. In 2002 nearly 30,000 farms had implemented salinity management practices: some 3.2 million ha of crops, pasture and fodder were planted for salinity management along with 776,000 ha of trees; about 446,000 ha of land was fenced to manage salinity and over 200,000 km of earthworks (banks, levees and drains) had been built. Just over 7,000 irrigated farms had made changes to irrigation practices for salinity management.3
Different strategies suit different regions because salinity control invariably involves trade-offs between social, financial and environmental goals. And better understanding of salinity provides an opportunity for forestalling problems in northern Australia.
Land use: Agriculture
Cattle and sheep numbers
Agriculture is the major form of land use in Australia. In 2002, 58% of Australia was used for agricultural activity: 3% for crops, 3% for pastures and grasses4, with the remaining 52% of land holdings mainly used for grazing. Different agricultural activity affects the land in different ways, and the effects of land clearance (a necessity if crops are to be grown or pasture sown) are discussed in the biodiversity section of the Natural landscape dimension.
Once land has been cleared of native vegetation, the impacts of agriculture depend on the crops grown and farming practices used. While 24 million hectares (ha) of Australian land were used for growing crops in 2002, far more of Australia was used for grazing sheep and cattle.4
Until recently, interest in the links between changes in land use and the conservation of Australian biodiversity have focused on southern and eastern Australia where broad-scale clearing has been widespread.5 There is now a growing appreciation of the effects of changes in land use on central, western and northern Australia.
The pastoral industry covers about half of the continent. Numbers of cattle have increased almost four-fold since 1903, from 7 million cattle to 27 million in 2003. Numbers of sheep were 80% higher in 2003 than they were in 1903 (about 98 million sheep in 2003 compared to 54 million in 1903). But sheep numbers in 2003 were considerably lower than periods in the 1960s, 1970s and late 80s. The national flock peaked in 1970 at almost 180 million animals.
Grazing by stock in arid and semiarid regions exerts a pressure on the land and is one of the major threats to native vegetation (along with grazing by feral animals and change in fire frequency).6
Altered fire and hydrological regimes and invasive species (including exotic grasses introduced in an attempt to improve pasture) have had potentially significant effects on the biodiversity of arid and semi-arid Australia. Increases in the number of large herbivores have also had a direct impact. Domestic and feral livestock remove vegetation cover and break up the soil surface, exposing it to wind and water erosion, while an increase in pasture and numbers of watering points, and a reduction in dingoes, appear to have helped some species of kangaroos to increase in numbers in some areas. Kangaroos also put pressure on vegetation cover.
Australian land use, 2001
Native forest tenure - 2003
Land use: mining
|Public multiple-use forests|
|Other crown land|
|Nature conservation reserves|
|Source: National Forest Inventory.7|
There are many mines throughout Australia, though less than 1% of our total land area is used for mining or by mining leases.8 Some sites are affected by land clearance or waste disposal, while the roads and infrastructure that provide access to remote mines have also had an impact on the environment.8 Pollution from mine sites can affect the air, water and land, and some of the toxic compounds used to extract minerals at mines are a particular concern.
It is difficult to assess changes in the effects of mining on the Australian environment over recent years, but the mining industry has taken steps to reduce its impact on the environment. In 1996, for example, the Minerals Council of Australia instituted a self-regulating environmental code of practice to provide effective monitoring and reporting of mine site and mineral processing operations. Forty one companies had signed up to the revised code by July 2002, who together accounted for 300 operations and 92% of Australia's mineral production.9
Land use: native forests
In 2001 there were an estimated 163 million ha of native forest in Australia. More than 12% of this forest was in nature conservation reserves. The majority of native forest in Australia was eucalypt forest (nearly 80%), with acacia forest accounting for another 10%. 7
Plantation forests are an important source of timber. In 2001-02, 60% of the $1.3b worth of logs taken to saw mills or exported came from plantations.7 When planted on land that was previously cleared, plantations can bring environmental benefits, such as lowering the water table (and hence reducing salinity) or reducing erosion.
However, plantations (whether exotic or native) have vastly simplified ecosystems - with fewer species of plants and animals - when compared to forests that have matured over thousands of years. Plantations can also assist the spread of pests and disease, and can increase the risk of exotic species invading nearby areas of natural forest. Therefore we focus here on the progress of Australia’s non-plantation forests.
|Regional Forest Agreements|
Regional Forest Agreements (RFAs) are a significant recent change in the management of Australian forests. RFA s were entered into between the Commonwealth Government and state governments to try to guarantee access to forest resources and set up an adequate, comprehensive and representative reserve system for the biological diversity of Australian forests.
As part of the process, old-growth forests were mapped systematically and comprehensively for the first time.5RFAs have led to an increase of about 1.7 million ha of forest area included in conservation reserves between 1997 and 2002.7
The process has attempted to balance conservation with social and economic concerns. Some people still believe that all logging in old-growth forests should be stopped, while others believe that too much land is now protected from commercial harvesting.
Our forests are an important carbon sink (i.e. they absorb the greenhouse gas CO2, as discussed in the Greenhouse gases commentary). They are used for many purposes, including recreation, biodiversity conservation, timber harvesting (the forestry industry and associated wood and paper manufacturing are important sources of income and work in Australia, particularly for some towns), water catchment protection and honey production. All of these uses have impacts on the natural landscape, but the extraction of timber has attracted most attention.
The environmental impacts of timber harvesting are of greatest concern in native forests, where clearfelling and associated fire regimes frequently result in major changes to the species composition and structure of forests.10 Forestry can damage soil structure, cause siltation of streams and rivers, and assist invasive plants and animals to spread.
One major impact of timber extraction is on animals that live in tree hollows. About one in seven of our vertebrate species (mammals, birds, frogs and reptiles) depend on tree hollows.11 Suitable large hollows tend only to develop in trees older than 150 years, but sections of forests are typically logged every 55-120 years,11 which means that large hollows will not develop in logged forests unless habitat trees are retained by forest management agencies.
The number of trees left standing to develop hollows has increased in recent years because of changes to the Codes of Forest Practice during the Regional Forest Agreement process (see box). In south-east NSW for example, only one hollow bearing tree was retained on every three hectares in 1991. By 1997 this had risen to 15 trees retained on every three hectares.12
Assessing change in forest areas during the 1990s is difficult. Although the National Forest Inventory released data for Australia's forest area in several years, changes between years come from a range of factors, particularly from improvements in mapping, as well as actual change in forest area.
Areas with high potential to develop dryland salinity
High potential 2000
High potential 2050
4 363 000
5 658 000
17 000 000
|Source: National Land and Water Resources Audit.2|
Some differences within Australia
More than half of Australia's dryland salinity problems are predicted to occur in Western Australia (the south-west of the State in particular, one-third of which is predicted to be at risk by 2050).2 Much less land is currently affected by salinity in Victoria and Queensland, although in both states it could rise to over 3 million ha by 2050.
Northern Australia has far less dryland salinity than temperate Australia, although experts believe it is not necessarily immune to the problem.2
Factors influencing change
|Improved land management|
The 2001 State of the Environment report concludes that the response to the continued pressures on Australian landscapes is improving, although it is too early to know whether it will result in an improvement in land condition.5
Since the late 1990s there has been substantial investment in Landcare and Bushcare programs. Landholder and community groups plant many millions of trees each year and, in 2000-01, more than 50% of farmers participated in some type of landcare activity.13 Volunteers work around the country such as those working on the Paddock Adoption Program at Calperum and Taylorville stations near Renmark in South Australia. The stations cover over one-third of the 900,000 ha Bookmark Biosphere reserve, which is managed by a partnership of government, non-government and private landholders.14 The volunteers' work, which involves activities including fox and goat control, helps protect threatened species like the Mallee Fowl.
By 2001, two-thirds of grain farmers had adopted land management practices aimed at preventing land degradation.5 Surveys indicate that farmers now plant or protect trees primarily for shade, environmental conservation or land rehabilitation, and not for commercial purposes.5 And more than 7.5 million ha of Australian farmland are managed organically.5
Australia's soils are, in places, naturally saline. But salinity has been exacerbated by human activity, mainly agriculture. In some regions, problems originated over 100 years ago, from factors including excessive land clearance and large scale planting of pasture and crops that used relatively little water, pressures which remain today. In other areas salinity is coming to light after more recent land use changes. Because some of the problems began so long ago it is very unlikely that they can be repaired easily. Salinity problems, for instance, only become apparent after long time lags, often 100 years or more (depending on the soil type).2
The National Action Plan for Salinity and Water Quality was endorsed in 2000 by the Council of Australian Governments. Under the plan, 21 priority regions have been targeted and governments and communities are working together to prevent, stabilise and start to reverse trends in dryland salinity, and improve water quality.
Links to other dimensions of progress
Some forms of agricultural production, land clearance and other factors such as the weather can all contribute to salinity. National income and wealth are also affected, not just through the loss of agricultural production but also because of damage to roads, rail and buildings (the severity of these effects varies considerably from region to region).
Salinity is a major threat to the health of many inland water systems. (Soil erosion, another form of degradation, can affect inland waters too, as well as estuaries and inshore marine environments, such as the Great Barrier Reef.)
Some 630,000 ha of native vegetation are at risk already from salinity, and this is predicted to rise to more than 2 million by 2050.2 This degradation of both water and native vegetation will impact upon biodiversity in affected areas. In Western Australia for example, some 450 endemic plant species are threatened with extinction from salinity,1 while Western Australia's Conservation and Land Management department has estimated that there has already been a 50% decline in waterbird species using wetlands in the Western Australian wheatbelt because of the death of vegetation due to salinity.15
Land clearance can lead to soil erosion and, when it results in a changing water balance, it leads to dryland salinity. Soil erosion, which is also linked to overgrazing from both livestock and invasive species such as rabbits and goats, can cause fine particle air pollution.
See also the commentaries National income, National wealth, The natural landscape - biodiversity, The natural landscape - inland waters, The natural landscape - invasive species, Oceans and estuaries and The human environment.
The natural landscape - inland waters
Progress and the headline indicator
1 National Land and Water Resources Audit (NLWRA) 2002, Australians and Natural Resource Management 2001, NLWRA, Canberra.
2 National Land and Water Resources Audit (NLWRA) 2001, Australian Dryland Salinity Assessment 2000, NLWRA, Canberra. The NLWRA's salinity projections are based on a range of assumptions and data including an assumption of a continued rate of increase and no change to water balances.
3 Australian Bureau of Statistics 2002, Salinity on Australian Farms, 2002, cat. no. 4615.0, ABS, Canberra.
4 Australian Bureau of Statistics 2003, Agricultural Commodities, 2001-02, cat. no. 7121.0, ABS, Canberra.
5 State of the Environment Advisory Council (SoE) 2002, Australia - State of the Environment Report 2001, SoE, CSIRO Publishing, Melbourne.
6 National Land and Water Resources Audit (NLWRA) 2001, Rangelands - Tracking Changes, NLWRA, Canberra.
7 Bureau of Rural Sciences 2003, National Forest Inventory Database, BRS, Canberra.
8 State of the Environment Advisory Council 1996, Australia - State of the Environment Report 1996, SoE, CSIRO Publishing, Melbourne.
9 Minerals Council of Australia 2004, Sustainable Development Report, 2002 <www.minerals.org.au/downloads/pdf/sd_report02.pdf> last viewed 11 February 2004.
10 Mackey, B., Leslie, R., Lindenmayer, H., Nix, H. and Incoll, R. 1998, The Role of Wilderness in Nature Conservation: A Report to the Australian and World Heritage Group, Environment Australia, Canberra.
11 Gibbons, P., Lindenmayer, D.B., Barry, S.C. and Tanton, M.T. 2000, 'Hollow formation in eucalypts from temperate forests in south eastern Australia', in Pacific Conservation Biology, Vol. 6, pp. 218-228.
12 Recher, H.F. 1996, 'Conservation and management of eucalypt forest vertebrates' in Conservation of Faunal Diversity in Forested Landscape, eds DeGraff, R. and Miller, I., pp. 339-388, Chapman and Hall, London.
13 Australian Bureau of Statistics 2002, Agricultural Survey: Farm Business Operation and Management, Australia, 2001-2002, cat. no. 7111.0.55.001, ABS, Canberra.
14 The Natural Heritage Trust 2001, The Journal of the Natural Heritage Trust, No. 10, Environment Australia and Agriculture, Fisheries and Forestry - Australia, Canberra.
15 Dillon, B., Lewis, S., Holmes, A., McNamara, K., Burley, J., Hofman, H., Briggs, S., Lyon, P., Scott, A., Loan, L. and Saunders, D. 2001, Implications of Salinity for Biodiversity Conservation and Management, Task force report for ANZECC Standing Committee on Conservation.
Water is fundamental to the survival of people and other organisms. Apart from drinking water, much of our economy (agriculture in particular) relies on water. The condition of freshwater ecosystems has a critical impact on the wider environment.
Some 80% of Australia is classed as semiarid, making this the driest inhabited continent. But our low population density means we have more water than many countries in per-capita terms.1 However, we also have one of the world's highest levels of water consumption per head,2 and water supply and demand vary strongly across the country. In the tropics, for example, only a fraction of available fresh water is used by people. In other areas, such as the Murray-Darling basin, pressure on water resources is acute.
Ideally the headline indicator would consider the health of Australia's freshwater ecosystems. Changes in the quantity and quality of all surface and groundwater would be measured, together with impacts from factors such as invasive species and changes to river flow. But such data are unavailable for much of the country, so we focus on water use, and consider the proportion of Australia's water management areas within which water extraction is thought to be sustainable.3
In 2000, about 11% of Australia's surface water management areas were overdeveloped. Another 15% were approaching sustainable extraction limits (i.e. highly developed). Some 11% of groundwater management units were over-developed, and a further 19% were highly developed.
A variety of information from around the country points to a decline in some water resources. Increased water use in areas such as the Murray-Darling Basin during the past 10 years will have contributed to a decline in river health. Data from the National Land and Water Resources Audit (NLWRA) show that turbidity was a worsening problem in Australia, while more than half of the basins it assessed had increasing nutrient loads, and just under half of the basins assessed for salinity showed increasing trends.4 Factors including sedimentation, pollution, and the spread of exotic fish and aquatic weeds have all contributed to a decline in biodiversity. However, although overall water extractions increased during the last decade, residential water use per household appears to be declining.5
Net water use
In 1983-84, Australia used an estimated 14,600 gigalitres (GL) of water. By 1996-97 this had risen to 22,200 GL, an increase of over 50% in 14 years.6
There was some fluctuation in use through the mid-1990s, perhaps in part because of the influence of our highly variable climate, but overall the trend was one of increasing use. Water use rose by 3,600 GL between 1993-94 and 1996-97; a large proportion of this increase is attributed to agricultural activity, in particular livestock, pasture, grains (excluding rice) and other agriculture.6 There were also increases in the use of water in the rice and cotton industries, with smaller increases for use among farmers growing grapes, or other fruit and vegetables.
Net water use(a)
Water resource development
Water resource development has been integral to the growth of Australia's economy, towns and cities. It has also affected the health of many river systems.
As human settlements and agriculture increased in the nineteenth century, so did the need for reliable water supplies. Australia's unpredictable climate caused highly variable river flows which could not support intensive settlement.7 Dams were built to regulate rivers and store water, primarily for domestic, industrial and agricultural use.
The number of dams in Australia increased during the first half of the twentieth century, but the increase was particularly rapid after the 1950s. Australia now has over 80 major dams, each with a capacity greater than 100 GL. (One hundred GL is the volume of water contained in 100,000 Olympic-size swimming pools).8 However, only one major dam was constructed between 1991 and 2001.
Dams greater than 100 gigalitres
Dam construction and water diversions have influenced the hydrology and ecology of some of our river systems. The patterns of flow in some rivers, once highly variable, have been changed and the flow of water has been reduced. Some of the impacts of these changes are discussed below.
Groundwater is also an important resource. Up to four million Australians are totally or partly dependent on groundwater for domestic water supplies.5 In 1996-97 approximately 5,000 GL of groundwater were extracted.9Groundwater and surface water systems are connected to each other to varying degrees in different parts of the country. The use of one affects the other. However, the interactions between the two systems are not well understood in most parts of the country. Relatively little is known about the impact of groundwater extraction on the Australian environment: many land and water ecosystems are dependent on groundwater for at least some of the time, but the interactions between groundwater and these systems are quite poorly understood.
Urban water use
Although Australia’s water use increased by about 20% between 1993-94 and 1996-97, urban water use per person in several state capitals declined, in part at least because of an increased awareness of the need to reduce water wastage along with changes in water pricing. Industrial use of urban (as opposed to all) water is falling as industries become more water efficient.4In a typical Australian household people use more than 270 litres of water a day. Gardening is responsible for up to half of the water used each day; flushing toilets uses about another quarter.4 People in Asia, Africa and Latin America typically use 50-100 litres of water a day, although in the USA people use 400-500 litres a day.
Effects of development
The development of water resources has had many effects on freshwater ecosystems. In 2002, the NLWRA produced an Environment Index that assessed river condition depending on the nutrient and sediment in the water, the hydrological and catchment disturbance, and the condition of streamside vegetation.10 The degree of modification depends on the extent of change from these factors. A moderately modified river, for example, has a catchment dominated by land uses that disturb the river, with associated water extraction, habitat changes (such as a reduction in streamside vegetation of 50%-75% of original cover) and loads of sediment or nutrients above natural levels. Some 90% of Australian rivers were assessed. Among these rivers, the index found that:
- 66% of river length was moderately modified
- 19% was substantially modified
Two-thirds of river length assessed in the Northern Territory is in largely unmodified condition, as is about two-fifths of Tasmanian river length assessed. In the other states and territories more than 80% of assessed river length was moderately modified or worse. 10
- 1% was severely modified.
Irrigation and tree clearing have caused rising water tables and increased the salt in groundwater in many places. This increasing salinity is a threat to the health of our aquatic ecosystems and our water supplies.5
|Protecting Australia’s inland waters|
Australian governments and others are responding in a number of ways to the continuing deterioration in the health of many bodies of water. Although overall water use has risen (most of Australia's water is used by agriculture, which is also largely responsible for the increase), there was a decline in domestic water use for most large urban centres during the 1990s. The decline has been linked to a combination of water pricing, consumer education, the use of water-saving appliances and higher residential densities (linked to smaller gardens and lower outdoor water use).5 There is potential to get more from the water we extract: on average only 77% of diverted water reaches the customer; the rest is lost to seepage or evaporation.9
Governments have introduced a range of reforms to the water industry, which have included creating a market for water so that it can be reallocated to higher value crops or uses. And in southern and eastern Australia, caps on extraction (such as that operating in the Murray -Darling Basin) are being introduced to try to prevent further degradation of inland waters and provide better security of supply for industry. Recent initiatives aimed at protecting inland waters include the Council of Australian Government’s 2003 National Water Initiative, the Commonwealth’s National Action Plan on Salinity and Water Quality (2000) and the Murray-Darling Basin Commission’s 2003 Living Murray initiative.
Although there is still much to learn, research and reporting into Australia's water resources by the National Land and Water Resources Audit, the ABS, State of the Environment Reporting programs and state and territory water management agencies are improving our knowledge of this valuable resource.
Drinking water for most of South Australia and many inland towns in New South Wales is at risk from increasing salinity.5 If salinity is not controlled in the Murray River, Adelaide's drinking water has been predicted to exceed guidelines for salinity on two days in five by the year 2020.5 Nationwide, 80 of 851 nationally important wetlands are affected by salinity, and this is predicted to rise to 130 by the year 2050. Many of these wetlands contain species at risk from salinity.5 The causes of salinity and its impact are discussed in the commentary Land.
The removal of streamside vegetation allows increased sediment into the river, which can add nutrients and pollution harmful to aquatic species and overall river health. This vegetation is seriously degraded in many catchments from clearing, grazing and salinity: in some areas of Western Australia, for example, 50% of rivers and creeks have lost their streamside vegetation and fewer than 10% of wetlands have healthy fringing vegetation.5
There are as yet few nationwide data on the extent and impacts of pollutants entering inland waters. Although Australia uses much lower levels of pesticides than other OECD countries, pesticide use is thought to have increased strongly here since the early 1980s.5
Cotton, rice, sugar cane and horticultural crops are the highest users of pesticides.5 Since 1990 at least 20 fish kills in New South Wales rivers have been attributed to pesticides.5 Other pollutants, such as heavy metals and oil, may have localised effects. But in some states and territories at least, the management of these sources has improved in the views of the State of the Environment Committee.5 For example, stormwater management plans have been set up for all urban catchments in New South Wales, while the use of pollution licensing systems has increased throughout Australia. 5
Effects of development - river flow
Water resource development has altered the seasonal characteristics, rate and variability of flows in many river systems. For example, the flow of the Murray River at Albury would naturally peak in spring and be at its lowest in February. Now, water is stored in dams in winter and spring and released for irrigation in summer and autumn. As a result, peak flows, which are reduced, occur in summer, with minimum flows in the winter.13
Ecological processes have been altered by changes in the size and variability of flows. Natural wetting and drying processes have changed, and many in-stream habitats, floodplains and wetlands have become permanently flooded.14 This, in tandem with the overall decrease in flows, has led to a reduction in available habitat and also reduced the reproductive cues of many aquatic species.14,15 And so the reproductive patterns of both wetlands water birds and native freshwater fish have been affected, leading to a decline in their abundance.
Natural and actual flows per month, Murray River at Albury - 1998-99
The release of cold water from storages has also affected the reproductive cycle of many aquatic species,13 while changes in flow patterns have helped exotic species, such as carp, to spread and out-compete native species.15 Reduced flows are one factor that can lead to more severe algal bloom outbreaks because of stagnation.
Algae are tiny organisms and an important part of the food chain. But when some algae multiply in sufficient concentrations to 'bloom' they can poison the water, affecting people, wildlife and livestock. Some types of algae are not toxic, but others carry poisons that can cause liver damage or tumour growth, acute poisoning and paralysis in animals, and skin and eye irritation.11
Outbreaks of algal blooms have been recorded as far back as 1878 in Australia;11 but they are now far more common. Blooms are often indicative of a decline in the ecological health of freshwater systems. They are not caused by a single factor and can occur in urban or rural areas. They are most common in storages, lakes, wetlands and stretches of rivers that have still waters and are enriched with plant nutrients, nitrogen and phosphorus (these substances can enter water from fertiliser run-off, fish farms, sewage and stock manure as well as from urban storm water). They are a significant problem in reservoirs and other water storage areas because of the increased costs of treatment, management and sometimes provision of alternative water supplies.
The location and frequency of algal blooms vary across Australia, but they are common and persistent in many waterways throughout Australia where they impose a significant economic cost on the community, industry and government in both urban and rural areas.5
It has been estimated that algal blooms cost Australian water users over $150m annually. 12
Water diversions(a), Murray-Darling Basin - 1933 to 2003
|The Murray-Darling Basin|
The Murray-Darling Basin covers 14% of Australia's area and is an important agricultural centre. The basin contains around 75% of Australia's irrigated land and supports 40% of all Australian farms.20 The river system, which for many years was primarily devoted to irrigation, is showing signs of environmental stress: salinity, loss of fish species and algal blooms.18 The graph shows the quantity, in gigalitres (GL), of water diverted from the basin's river systems, which is the key pressure on the health of its freshwater ecosystems (the condition of these ecosystems also depends on factors such as the timing of extraction and land management practices).
Water diversions have increased steadily since 1930. The amount of water diverted increased substantially in the early 1950s. More recently, average annual diversions between the periods 1989-1993 and 1999-2003 fell by 3%, largely driven by a decline in water use in Victoria and New South Wales (where use fell by 13% and 7% respectively), partially offset by an 8% rise in use in South Australia and a 9% rise in Queensland. Some 95% of diverted water is used for irrigation, and New South Wales used just over half.
In the late 1990s, environmental degradation and increasing water demand led to a ‘Cap’ on river diversions in the Murray-Darling Basin. The Cap was seen as a first step towards achieving a better balance between production and the environment. Because of continuing environmental degradation in the Murray-Darling Basin, a major initiative called 'Living Murray' is now under way. As a first step in this initiative in 2003, 500 GL of water was made available for environmental flows. The water will be targeted at achieving the desired environmental outcomes at six icon sites along the river Murray.
Native freshwater fish
Of over 200 native species of freshwater fish in Australia, the Commonwealth lists 11 species as endangered and 10 as vulnerable to extinction.16 There are at least six threats to our fish: degradation of habitat; pollution; reduced environmental flows; barriers to fish migration; introduced species; and fishing pressures. The extent of each threat varies across Australia, reflecting differences in water resources and urban and agricultural development. While fishing has played a role in the decline of fish populations, the modification and degradation of fish habitats have had the most substantial impact.17
The construction of dams, for example, has altered fish habitat by creating a barrier to movement, changing water temperatures, altering flow patterns and reducing water flow. Changes to natural flooding regimes have had different effects, such as allowing exotic fish like the European Carp to dominate or out-compete native species (the latter are less able to adjust to the new regimes). This has led to the decline of native fish in lowland regions of the Murray and Murrumbidgee rivers. 13
Some 35 exotic fish species have become established in inland waters, with eight identified as having a significant impact.5 Many were introduced into Australia for ornamental or fishing purposes.18 Some, such as trout and carp, are harming native fish. Carp feed by uprooting and killing aquatic plants which native species feed on. The carp thereby disrupt the river bank and stir up sediments which free nutrients that enhance toxic algae (they also contribute to algal blooms by preying on the species which feed on the algae).19
Five species of trout and salmon have been introduced to Australia, and over 5.5 million exotic trout and salmon were stocked into our inland waters in 1998-99 alone, although some of these were into artificial compounds where exotic stock can be monitored to try to prevent risk to native fish.18 Trout have had an impact on the native galaxid family of fish, nine species of which are considered to be at risk. Adult trout are known to eat galaxids, while juvenile trout compete with galaxids for food.21
Some differences within Australia
Some 70% of water used nationally in 1996-97 was used by agriculture.6 In order to compare the amount of water used by industries of different sizes, one needs to standardise by size. The value of industry value added (IVA, which looks at the value of goods and services sold less the cost of intermediate inputs) per megalitre (ML) of water used is one standardisation. In 1996-97, agriculture had the lowest IVA per ML water used ($588/ML) (i.e. it used more water than any other industry relative to its size). Manufacturing's ratio, by contrast, was about $87,500 IVA per ML of water.6
Among different irrigated crops, vegetable and fruit growing returned the highest gross value added per ML of water used, returning respectively about $1,800 and $1,500 in 1996-97. The rice industry had the lowest ratio of gross value added per ML water used (i.e. it used more water than any other crop industry relative to its size) at around $190 in 1996-97.6
River condition (biota index), by state
% of sites assessed where biota was
|Source: National Land and Water Resources Audit.5|
|The National Land and Water Resources Audit (NLWRA) has recently published an index of river condition.5 NLWRAs assessment collated and interpreted data for rivers in the more intensively used parts of Australia. The assessment builds on other river assessment initiatives such as the National River Health Program. The data are based on the work of scientists who examined the water to measure the diversity of macroinverterbrates (bugs) that inhabit different stretches of river. Because macroinvertebrates are sensitive to changes to river catchments (e.g. land clearing) as well as changes to the condition of the river (e.g. water quality) and spend much of their life in the river, they are good indicators of river condition.|
The data show that 23% of assessed sites were significantly impaired, and had lost 20%-50% of macroinverterbrates expected to be present. A further 6% were severely impaired (had lost 50%-80% of expected macroinvertebrates) and 2% were extremely impaired (had lost more than 80% of expected macroinverterbrates). The majority of impaired river basins were in New South Wales.
Source: National Land and Water Resources Audit 2002, Australian Terrestrial Biodiversity Assessment 2002, NLWRA, Canberra.
|Wetlands and Riparian Zones|
Australia probably has the most variable wetland and floodplain systems in the world, reflecting the nature of our climate, particularly in the inland. Wetlands are essential for maintaining biodiversity, and the NLWRA found that about 50% of wetlands are estimated to have been destroyed since European settlement. The NLWRA’s assessment of biodiversity reported on the condition of 851 nationally important wetlands (classed as important because of their role in protecting biodiversity and ecological processes). They assessed wetlands and riparian zones as either degraded (recovery unlikely in the medium term); fair (recovery requires significant intervention); good (recovery in short-term with minimum intervention); and near pristine. The report found that:
- Some 58% of the wetlands assessed were in good condition. These wetlands occurred principally in northern and eastern Australia. Nationally important wetlands in several subregions - on Cape York Peninsula, Tasmania and parts of the Channel Country - were assessed as near pristine. The nationally significant wetlands in the rangelands and south-west of Western Australia, and most of New South Wales were in fair condition or degraded.
- Changes in the condition of wetlands were also assessed. The condition of wetlands in 59% of subregions was static, and was declining in 37% of subregions assessed.
Rivers and their riparian zones have a fundamental role in the functioning of ecosystems. The NLWRA found that:
- Riparian zones were assessed as fair in 38% of subregions and degraded in 31% of subregions.
- The trend in the condition of riparian zones across 73% of Australia was one of decline, with over grazing, exotic weeds, changed hydrology, increased fragmentation, feral animals and changed fire regimes all listed as common threats.
Factors influencing change
In Australia, patterns of low rainfall vary over the years, and so climatic variation is a major influence on water use. Over the longer term, population growth has led to increased water use, but its contribution has been small in recent times. The main changes in the 1990s (and recent decades) have come from increased agricultural and industrial use (to a large degree, these are independent of population growth).
Most of the 19% rise in total water consumption between 1993-94 and 1996-97 was due to the agricultural sector; which increased water use by 28%;6 despite an increase in the sector's real gross value added of less than 10% over the period.22
Changes in economic activity affect water use, each industrial sector using water according to its size and needs, so the economy's industry composition is important. New industries, such as those in the growing service sector, use water much less intensively than agriculture, manufacturing and mining, and so the economy as a whole is now less reliant on intensive water use. In theory at least, future economic growth could be accompanied by reduced water use. Meanwhile, a greater focus on efficient use of water has led to an increase in the volume of waste water re-used. In 1996-97 approximately 134 GL of water were reused, up from 94 GL in 1993-94.6 At less than 5% of all waste water, this figure has the potential to grow significantly.
Australian governments are working on a framework for 'water reform' aimed at halting degradation in inland waters and minimising unsustainable use. Its main elements include provisions for water entitlements and trading, environmental requirements, institutional reform, water pricing, research and public education. Recent initiatives aimed at protecting inland waters include the Council of Australian Government's 2003 National Water Initiative, the Commonwealth's National Action Plan on Salinity and Water Quality (2000) and the Murray-Darling Basin Commission's 2003 Living Murray initiative.
Experts debate the impacts of water use and land clearing in different areas. For instance, a salinity audit conducted in the Murray-Darling Basin predicted that if nothing is done, the average salinity in half of the basin's Rivers will exceed World Health Organisation (WHO) standards for drinking water by 2100 because of their salinity (fewer than 10% of rivers fall into this category at the moment).23
Links to other dimensions of progress
Economic production, in particular agriculture, is the major user of water. Water degradation is strongly linked to inappropriate land management (often in the past) such as land clearance and forms of soil degradation, while much of our biodiversity depends on healthy freshwater ecosystems.
The quality of our inland water and changes to the land are linked to one another. For example, increasing river salinity caused by dryland salinity can result in water becoming too saline for drinking or irrigation. It can also kill streamside vegetation. This, in turn, can increase erosion in river banks, which can cause further deterioration in water quality and loss of aquatic species.
Contaminated water can affect the health of ecosystems, people and livestock, while managing contamination involves a significant economic cost (e.g. the total costs of managing algal blooms were estimated to be in the order of $200m a year during the late 1990s).12
See also the commentaries Health, National income, The natural landscape - biodiversity, The natural landscape - land, and Oceans and estuaries.
1 World Bank 2002, 2001 World Development Indicators <http://www.worldbank.org/data/wdi2001/pdfs/tab3_5.pdf> last viewed
23 March 2004.
2 Gleick, P. 2000, The World's Water 2000-2001, The Biennial Report on Freshwater Resources, Island Press, Washington DC.
3 The National Land and Water Resources Audit (NLWRA) has made estimates of the sustainable yield of Australian groundwater and surface water resources. It defines sustainable yield as the volume of water that can be extracted without affecting other users and the environment. These preliminary estimates were used in compiling the headline indicator data; additional scientific data and knowledge are required before the sustainable yields can be determined conclusively.
4 The National Land and Water Resources Audit 2001, Australian Water Resources Assessment 2000, National Land and Water Resources Audit, Canberra.
5 State of the Environment Committee 2002, Australia - State of the Environment Report 2001, CSIRO Publishing, Melbourne.
6 Australian Bureau of Statistics 2000, Water Account for Australia 1993-94 to 1996-97, cat. no. 4610.0, ABS, Canberra.
7 Murray-Darling Basin Commission (MDBC) 1990, The River Murray system, The Regulation and distribution of River Murray Waters, MDBC, Canberra.
8 With an olympic swimming pool being 20m x 50m x 1m.
9 National Land and Water Resources Audit (NLWRA) 2001, Australian Water Resources Assessment 2000, Surface Water and Groundwater - Availability and Quality, NLWRA, Canberra.
10 National Land and Water Resources Audit. (NLWRA) 2001, Australian Catchment, River and Estuary Assessment 2001, NLWRA, Canberra.
11 Flett, D. and Thoms, M.C. 1994, 'Blue-green algae and our degraded waterways', in (eds) Hirsh, P. and Thoms, M.C., Australasian Geography for the 1990s, Department of Geography, University of Sydney, Sydney.
12 Land and Water Resources and Development Corporation (LWRDC) 1999, Cost of Algal Blooms. Submitted by the Atech Group to the Land and Water Resources and Development Corporation and The Murray-Darling Basin Commission, LWRDC Occasional Paper 26/99, Canberra.
13 Murray-Darling Basin Commission (MDBC) 2000, Impacts of Water Regulation and Storage on the Basin's Rivers, MDBC, Canberra.
14 Kingsford, R.T. 2000, 'Ecological impacts of dams, water diversions and river management on floodplain wetlands in Australia', Austral Ecology, Vol. 25, pp. 109-127.
15 Gehrke, P.C., Brown, P., Schiller, C.B., Moffatt, D.B. and Bruce, A.M. 1995, 'River regulation and fish communities in the Murray-Darling River System, Australia', Regulated Rivers: Research and Management. Vol. 11, pp. 363-375.
16 The Environment Protection and Biodiversity Conservation Act 1999, Commonwealth Government of Australia.
17 Davies, K.M., Kearney, R.E. and Beggs, K.E. 2000, 'Research priorities for Australia's Freshwater Fisheries', Australian Journal of Environmental Management, pp. 28-37.
18 Australian Bureau of Statistics 2001, Australia's Environment: Issues and Trends, cat. no. 4613.0, ABS, Canberra.
19 Crabb, P. 1997, Murray-Darling Basin Resources, Murray-Darling Basin Commission, Canberra.
20 Murray-Darling Basin Commission (MDBC) 2000, Review of the Operation of the Cap: Economic and Social Impacts, MDBC, Canberra.
21 Cadwaller, P.L. 1996, Overview of the Impacts of Introduced Salmonids on Australian Native Fauna. Australian Nature Conservation Agency, Canberra.
22 Australian Bureau of Statistics 2001, Australian System of National Accounts, cat. no. 5204.0, ABS, Canberra.
23 Murray-Darling Basin Commission (MDBC) 1999, The Salinity Audit of the Murray-Darling Basin. A 100 year perspective, MDBC, Canberra. (These forecasts are complex and should be treated cautiously.)