Thematic findings: Land
ndependen Report to the Commonwealth Minister for the Environment and Heritage
Australian State of the Environment Committee, Authors
CSIRO Publishing on behalf of the Department of the Environment and Heritage, 2001
ISBN 0 643 06745 0
The word 'land' carries strong emotional overtones. Land is territory; it is what peoples and nations have always fought for. Land means food, security, wealth and power. Societies have a powerful need to feel and express a sense of place in the art, song, poems, pictures and fables of their culture.
At the end of its first century of federation, Australia is in the process of redefining its cultural identity through changing attitudes to land and landscapes. Nowhere is this more evident than in the increased recognition of the significance of what land means to Indigenous Australians since the passing of the Native Title Act 1993.
In many parts of Australia, the historical predominance of agriculture as the economic driver and user of land, water and vegetation is being challenged by new economic activities and different values. Native title rights, service industries, tourism and recreation are already important. However, emerging new attitudes are placing increased value on landscape aesthetics, water quality, native vegetation and fauna. At the beginning of the 21st century, Australia is a continent in transition.
The three levels of government in Australia have traditional roles in land management. These roles have evolved and changed as Australia's constitution has been tested and interpreted over the last 30 years. Today, Australia is at a threshold as the states and the Commonwealth come to terms with the necessity to manage our continent at local and regional scales for continental outcomes. The EPBC Act has set the stage and this report is presented as the NAP for Salinity and Water Quality is being put in place (see Inland Waters thematic findings).
In considering the condition of land, there are six key issues, also discussed below:
- accelerated erosion
- altered habitats
- invasive species
- secondary salinity and acidity
- nutrient and carbon cycling
- soil and land pollution.
A summary is presented in Key findings at the start of this report.
SoE land indicators were developed to reflect the extent to which ecosystem functions are maintained (Hamblin 1998). Six geomorphic and biological processes that support such functions have been used as criteria (Table 9). Threatening processes are interpreted as those processes of human origin that distort or disrupt natural processes (see http://www.ea.gov.au/biodiversity/threatened/tssc.html). Much of the terrestrial biodiversity of Australia depends heavily on landscape function and integrity (see the Biodiversity theme report). For this reason, SoE (2001) focuses more on the functioning of ecosystem processes and the services that ecosystems provide than did SoE (1996).
|Geomorphic processes||Human interventions||Biological processes||Human interventions|
|Wind erosion-deposition||Clearing, overgrazing, cultivation||Carbon cycling||Fossil fuel burning, vegetation planting and clearing, cultivation, animal herding, grazing|
|Water erosion-deposition||Clearing, overgrazing, cultivation||Nutrient cycling||Manufacturing, fertiliser additions, vegetation changes, animal herding, cropping, bacterial manipulation|
|Chemical weathering||Altered hydrological regime, changed vegetation types, fertiliser use||Essential nutrient cycling (P, K, S, Ca, Fe, Mg, Mn, Zn, Cu, Co, Se, Mo and B)||Vegetation planting and clearing, animal herding and grazing, manufacturing, mining, landfill and wastes|
|Mechanical weathering||Surface soil changes (mulches, loss of cover)||Chlorophyll production||Plant domestication, change to plant organs, grass, cereal and crop monocultures, synchronous ripening|
|Fluvial processes||Dams, weirs, levees, canals, drains||Carbon reducers (soil biota)||Clearing of litter and top soil, fertilisation of farm soils, N and P microfloral inoculations|
|Fire||Deliberate firing for grass production, forest and human property protection and ecological management, and arson||Carnivorous consumers (humans and carnivores)||Exotic herbivores cultivated, permanent vegetation changes, reduction in non-human predators|
Source: after Hamblin (1998).
SoE (2001) attempts to understand how well ecosystem integrity and function are being maintained in Australia. However, the responses to the condition of our lands depend on the value system of that society. Also the evaluation of condition is itself value-laden, implying as it does a specified end use.
This section can be divided into two: a snapshot of the continent and a review of the six issues. Where conditions are improving at the continental scale, the influence of better seasons has been the greatest influence. Elsewhere, conditions are often deteriorating because the scale is so large and the resources that can be brought to bear are inadequate. Pressures are tending to increase in most cases. This occurs because of increasing economic activity, greater population pressures, inappropriate land uses and lack of resources to counteract long-term persistent pressures. However, government and community responses are increasing in number. In many cases, these responses are more relevant than a decade ago, but in some, the responses are not consistent, and have conflicting results.
Variable seasonality drives Australian ecosystems. The website of the Environment Resource Information Network (ERIN) provides a satellite view of the alternating but erratic flushes of green and brown that is Australia (Figure 15) (see http://www.ea.gov.au/land/monitoring/index.html).
Figure 15: NOAA images of 'flush difference' for 1993-94 and 1989-99 showing the difference in amount of seasonal greening between El Nio and La Nia years, respectively.
Source: Environment Australia (2001) using National Oceanic and Atmospheric Administration (NOAA) data
Since SoE (1996), Australia's land ecosystems have had less arid seasons than the first half of the decade, culminating in a very wet (La Nia) period in 1999 to 2000 (see the Atmosphere thematic findings). As a result of good rainfalls, many parts of the arid interior have more vegetation growth than at any time in the previous decade. In the central and southern interior, this has been further assisted by the up to 90% reductions in rabbit numbers following the escape and natural spread of rabbit calicivirus in 1995. In parts of the two-thirds of the continent that are used for grazing, there has also been some reduction in total grazing pressure following the drop in sheep numbers in response to low wool prices.
Regionally, there have been big differences in the net effect of rainfall, total grazing pressures, clearing, effect of fire and vegetation growth. Much of Queensland is still recovering very slowly from the effects of low seasonal rainfall between 1991 and 1994. Over the same period, western and much of southern Australia were little affected by low rainfall in the early 1990s and differences in vegetation growth have been smaller over the decade. However, in 2001, south-west Western Australia is experiencing an exceptionally dry period.
Agricultural holdings continue to influence 61% of Australia. Depending on the season, between 20 and 25 million hectares are sown to crops, and 94 million hectares of improved pastures are grazed (35 million hectares are sown to introduced legumes and grasses). There has been no clear trend in proportional land use, but annual fluctuations reflect changes in commodity prices, seasonal conditions and options for diversification. In the rangelands, however, there has been only a very small reduction of 3.7 million hectares (or 1.4%) in the total area of grazed leases.
Other land use changes have been similarly conservative, apart from an increase in the proportion of old-growth forests that have been added to the conservation estate. Australia has 16% of its 164 million hectares classified as native forest, set aside (Figure 16) in conservation reserves.
Figure 16: Location of forests, according to type, showing regions covered by RFAs
Source: National Forest Inventory (2000)
In response to both government and market forces, there has been an increase (30 000-90 000 ha/y) in new tree plantations. A net loss of native trees and woody species has continued, with probably more than 1.2 million hectares cleared over the past five years (1995-2000). However, estimates of tree loss for 1997 to 2000 are varied depending on the method of estimation. Knowing how much clearing is actually occurring is hugely problematic. The most reliable figures are provided by state and Commonwealth research agencies using remotely sensed data of tree cover changes adjusted for fire and drought. Despite this, conservation organisations continue to use licence permit numbers adjusted on past years whereas the Australian Bureau of Agricultural Resource and Economics (ABARE) uses surveys to ask landholders for area cleared. There is a pressing need to establish agreed national standards for measurement of land cover changes.
Since 1997, there has been substantial government investment in Landcare and Bushcare programs funded under the NHT. Landholders and community groups plant many millions of trees annually. In 1999, more than 80% of farmers said they had participated in some type of Landcare activity. However, the effect of this massive volunteer effort is still relatively small and the beneficial effects will not become apparent for a long time. The scale, both temporally and spatially, of the problems dwarf the noble efforts of the volunteers.
Intensification in land use is characteristic across most of the more densely settled regions of Australia. This has been formally characterised for state of the environment reporting purposes in a suite of indices for degrees of disturbance. The initial map coverage (in SoE 1996) has been progressively revised, and today less than half of the continent has a level of naturalness equivalent to that of pre-European occupation. In Victoria, less than 5% of the land is in this category, and Tasmania, often considered a wilderness destination for trekkers, has only 35% of land classed as remote and highly natural.
In SoE (1996), it was not possible to set baselines in many instances. However, there is sufficient information from that Report and other sources for SoE (2001) to assess whether there are any detectable trends for significant issues. No previous estimates are available for land pollution, and much of what is available is preliminary.
'Condition' indicators for land depend upon the prevailing seasonal conditions. Consequently, short-term changes in condition must not be interpreted as longer term trends, unless there are good historical data or modelling. Trends in social responses and, to some extent trends in human pressures, can be verified over shorter times.
Since 1996, over 66% of grain farmers have adopted some form of minimum tillage, direct drilling and stubble retention for at least some of their crops. Membership of Landcare groups has increased steadily. Current activities, however, cannot halt or quickly restore the extensive land degradation that has occurred. Many of these problems had their origin in the late 19th and early 20th century when the effects of overgrazing, exacerbated by severe droughts in the 1890s to 1900s, had a severe but not well-recorded impact. In Western Australia, New South Wales and Queensland, land degradation was accelerated by further extensive clearing after World War II. Secondary salinity becomes apparent only after lag phases of between 15 years (sandy regions of Western Australia) and 150 years (dense clays in riverine plains of the Murray-Darling Basin).
Although accelerated soil erosion (i.e. above that expected from natural erosion) continues to affect much of the arid interior and northern regions, 1995 to 2000 has seen some significant improvements (Figure 17). This is particularly marked where pastoral grazing management has been modified to allow natural restoration to take place. However, accelerated erosion continues to occur through the action of intensive storm events, with much of the erosion taking place in first-order streams that crisscross paddocks rather than in the more vegetated, larger stream channels.
Figure 17: Estimates of continental sheet erosion based on 1997 land use distributions, 1990 to 1999 (normalised vegetation difference index, NDVI) seasonal greenness and rainfall regimes.
Source: Lu et al. (2001)
Wind erosion remains a persistent feature of sandy soil crop lands, such as the Western Australian wheatbelt and in the mallee. The degraded mulga lands of south-west Queensland, western New South Wales, South Australia and south-east Northern Territory continue to be a source of windblown dust to southern and eastern Australia (Figure 18).
Figure 18: Dust storm index with 300 and 500 mm median rainfall lines, and accelerated erosion index for 1996 to 1999.
Source: McTainsh et al. (2001)
Satellite image of sediment plume extending 50 km from the mouth of the Gascoyne River two weeks after a major cyclone. SPOT image of 2 March 1995 showing the sediment plume from the flooding Gascoyne River, WA. Seriously degraded inland areas can also be seen in this image.
Source: WA Department of Land Administration, Remote Sensing Services.
Findings from recent data in Lu et al. (2001) show that the extent of land decline by erosion is not as severe as estimated. However, the effects of hydrological imbalance and consequential salinity on the landscape are a cause of concern.
Trend: Accelerated erosion
Pressures are reducing, condition is improving and response is variable.
People living in Australia's urban, southern and coastal regions continue to become concerned about a 'fragile and often degraded environment'. In these regions, the traditional pre-eminence of agricultural and mining land uses has been replaced by the competitive demand for urban land, tourism, recreation, aquaculture, service industries and retirement investments in rural-residential lifestyles.
Throughout Australia, but particularly in the north and west, Indigenous interests in land have become a factor in land transactions. This has been through direct purchase of land and through native title and land rights processes. In northern Australia, increasing concern for biodiversity conservation is juxtaposed against those who still see the north as the last frontier of development opportunity.
Land use change has been rapid in areas where net migration of people to previously rural regions of coastal New South Wales and southern Queensland, and along the transport corridors from Melbourne to Sydney, has occurred at growth rates of over 5% over the period. In coastal Western Australia, south of Perth, the growth rate has been over 7% per annum. Elsewhere in rural Australia, people have migrated towards larger towns and coastal regions. Increases in population in some interior statistical local areas has occurred through expansion of mining and service industries. Projections for the present period (see Human Settlements theme report) show these trends increasing.
Fragmentation of native habitats is increasing in the areas of rapid population growth, with variable responses from local and state planning authorities. Some coastal environments have been increasingly protected by the creation of national parks and reserves, with 63% of Victoria, 33% of New South Wales and 25% of Queensland coasts now protected. Since 1995, 60 000 hectares have been added to New South Wales coastal parks. In addition, 96% of the Victorian coast is publicly owned, and a consent process for coastal Crown land provides an opportunity for governments to ensure appropriate use and development.
Forested regions have been the focus of new management arrangements under RFAs in Tasmania, Victoria, south-west Western Australia, east coast of New South Wales and parts of south-east Queensland (see http://www.rfa.gov.au/ ).
Surveys indicate that there is an increasing diversity of attitudes to land and to trees in the landscape. Farmers themselves plant or conserve trees on farms primarily for shade, environmental conservation or land rehabilitation, not for commercial purposes. Landcare group membership has had a strong effect on farmer attitudes to farm trees.
Trend: Altered habitats
Pressure is constant or increasing, condition is deteriorating and response is improving.
Although the geological and geographical isolation has endowed Australia with a unique and highly endemic biota, it has also made the continent's flora and fauna particularly susceptible to the effect of invasive species. During the 1990s, mounting air and sea traffic has increasingly challenged the Australian Quarantine Inspection Service (AQIS). Over 220 incursions have been reported, a further 90 species already arrived have spread to other states, while another 110 species initially detected and eradicated have been re-reported and need re-eradication. The eradication of the Fire Ant in Queensland, for example, is expected to cost $123 million.
Since 1996, the proliferation of Internet trading has added to the problem of introductions (e.g. seeds can now be ordered over the Internet and posted to Australia). The recent outbreak of foot-and-mouth disease in the United Kingdom has demonstrated the potential catastrophic effect of the incursion of an exotic disease. In response, the Commonwealth government has increased funding to AQIS to improve surveillance of incoming passengers and goods.
Australia has insufficient resources to tackle even those species of identified national significance, let alone the threat from new incursions, and spreads of 'sleepers' or existing known problems (e.g. Diamondback Moth, Phytophthora spp., Western Flower Thrips - which all attack hundreds of endemic species). The risk assessment protocols, strategies for containment are all very weak for exotic threats in non-agricultural species.
Trend: Invasive species
Pressures are constant or increasing, condition is deteriorating and response is constant or increasing.
Dieback-affected native vegetation in south-west Western Australia.
Source: Environment Australia.
In many regions, land managers today are paying the costs of land remediation as well as paying the conversion costs associated with more sustainable practices. Since 1996, for example, it is estimated that an additional 0.5 million hectares of secondary salinity has become evident with the common cause being hydrological imbalance. The National Land and Water Resources Audit (NLWRA 2001a) has indicated that 5.7 million hectares are at risk from salinity. This area could increase to 17 million hectares by 2050 (Figure 19). A major challenge is to develop agricultural systems that, as a minimum, restore hydrological balance (see Drowning in a Dry Landscape).
Figure 19: Forecasted areas of high risk (predicted) or hazard (estimated) of dryland salinity by 2050 in Australia.
Source: NLWRA (2001a)
Since 1991, the area of soils affected by acidification has increased by an estimated 13 million hectares. This has occurred because of draining of coastal acid sulfate soils and from the continued acidification of agricultural soils. Acidification could be halted with lime applications, but these are uneconomic for landholders faced with very low returns from extensive animal farming.
A similar situation occurs with sodic soils (heavy soils with a large amount of sodium in their clay), which swell and disperse in water. Such soils occupy nearly one-third of Australia. When used for agriculture, they infiltrate rain very slowly, and plant growth is restricted by both lack of water and high pH. These soils improve in structure when they are conditioned with gypsum, yet the amount of gypsum applied is similarly small relative to the extent of potential benefit. Integration of agricultural land management and conservation management into landscape management is complex. The mining of soil conditioners such as lime and gypsum can cause environmental problems where these materials are located in areas of high biodiversity value.
Trend: Secondary salinity and acidity
Pressures are constant or increasing, condition is deteriorating and response is increasing (salinity only).
Fertiliser consumption has risen over the past two decades as farmers have altered agricultural production in response to the cost-price squeeze. Strategies for increasing the returns from agriculture include increasing yield per area, increasing the value of the product (e.g. from a low protein to high protein grain), changing the product to one of greater value (e.g. canola and grain legumes rather than barley or wheat), and developing controlled environment systems (glasshouses, intensive animal units, irrigated fruit and vegetables).
Nearly all such steps require higher use of fertilisers, pesticides, water and labour; they are much more demanding in terms of the management skills required. Horticultural crop production has more than doubled from a farm-gate value of $2.0 billion in 1987-88 to an estimated $5.1 billion in 1998-99.
Most improved pastures received annual dressings of phosphate fertilisers well into the 1970s and 1980s, but have had lower applications in the 1990s because of the lower returns from grazing industries. The phosphate bank built up in many such soils remains although it may not be available to plants. Soils are now often nutritionally deficient in potash and nitrogen. Low nutrient replenishment is as much a concern as overuse of fertilisers.
Fertiliser use increases the potential for nutrients to move through the landscape and enter coastal and inland water systems. This is a particular problem where soil erosion occurs and soil particles containing nutrients are mobilised. When combined with point-source pollution, this is a major concern (see the Inland Waters and Coasts and Oceans theme reports).
In 1998, when Australia became a signatory to the Kyoto Protocol, the reason for identifying gains and losses of carbon in landscapes became more urgent. The AGO is developing techniques to monitor woody and soil carbon through the use of geographical information system (GIS) remote sensing. This may provide sufficient data through a modelling approach on the result of land clearing in the 1990s.
Typical patchwork of land uses across mid-rainfall regions of eastern Australia.
Source: A Hamblin.
Most Australian cropping soils have probably lost about half their original topsoil organic matter through repeated cultivation and resultant oxidation of organic materials. However, although it may be possible to reverse the decline in soil organic matter, the achievement of such a change depends on institutional, economic and social factors.
Trend: Nutrient and carbon cycling
Pressures are constant or increasing, condition is static and response is increasing (carbon).
Contamination can be separated into point sources and dispersed sources. Point sources are where pollution is focused (e.g. around a mine, factory, treatment works or intensive animal unit). Dispersed (or diffuse) sources are where chemicals have been widely dispersed across the landscape and are subsequently mobilised. From July 1998, industrial facilities using more than a specified threshold for fossil fuel combustion, specified chemicals, or total nitrogen and phosphorus emissions have been required to monitor and report to the National Pollutant Inventory (NPI). Thirty-six substances were selected for reporting in 1998 to 2001, and 90 substances have been selected for initial monitoring from 2001. Although the NPI as yet has only limited data, most emissions being monitored are released into the atmosphere, while only 5% are discharged to land. The most significant problems associated with land emissions are those that are likely either to move into groundwater and streams. These include petroleum-derived polycyclic hydrocarbons, heavy metals and acid soluble metal salts. Animal waste effluents from intensive feedlots, abattoirs and dairying activities are not yet all covered by NPI guidelines. Dairy produce factories are required to report emissions from 1999-2000 if reporting thresholds are exceeded. Agricultural activities such as irrigation, crop production, intensive animal grazing and other primary extraction processes such as logging are not covered by the NPI process.
Australia uses much lower levels of pesticides and fertilisers than other OECD countries (e.g. from the 1970s, average fertiliser use was one-tenth the amount in the UK). Environmental contamination from such pollutants is also less than in comparable developed countries. One view is that very low levels of agricultural subsidies in Australia has kept the use of agrichemicals efficient, compared with other OECD countries, where the average level of subsidy was 40% compared with Australia at 9%, and New Zealand, 4%. Australia also has more than 7.5 million hectares under organic management.
Since 1996, there have been several concerted actions to reduce agrichemical use in the horticultural, cotton, grain and sugar cane industries. Many weeds have become resistant to herbicides and some insects to insecticides (e.g. resistance of the Cotton Bollworm, Helicoverpa armigera). Integrated pest management, with less reliance on a single group of chemicals, and more reliance on suitable cultural practices, is now widely used. The use of genetically modified BT cotton has enabled substantial reductions in insecticide use, although the environmental effects of the use of such materials are not fully understood.
Norwich Park mine in the Bowen Basin.
Total pesticide expenditure has grown from $670 million in 1995 to $920 million in 1999. This increase has been mostly for weed control, but dollars do not necessarily reflect their impact. Most new generation chemicals are so biologically potent that they need to be applied in a targeted manner at low rates. They are, however, between two and 10 times more costly than out-of-patent compounds. The rise in expenditure does not mean that the total amount of pesticides in the environment has increased.
Many of Australia's environments are little affected by pesticides. This single factor should be substantiated and used positively when marketing our goods as 'clean and green'. For those rural industries where pesticide use is heavy (and remains so to maintain levels of productivity and profitability), the most effective action is to provide the documentation on usage.
The number of pesticide violations in fresh food products is now almost nil in every category, according to the National Office of Food Safety. In addition, most agricultural land, comprising 90 million hectares of rough pasture and 442 million hectares of rangeland, has never had any pesticides applied other than for occasional locust control. However, environmental monitoring programs have found pesticide residues in surface water in regions associated with summer cropping.
There is a lack of a data on contaminated sites including industrial, urban, rural processing and orphan sites (i.e. where ownership and responsibility for remediation of a site is not clear) other than mining. The location of past contaminated sites and their management is a 'grey' area: regulation of small and medium enterprises that fall outside NPI are not well documented. In addition, a lack of scientific knowledge of effects on biota and pathways to groundwater and other water bodies still hampers monitoring and regulation. The cost of clean-up is often inhibitory except where high visibility leads to political pressure.
Trend: Soil and land pollution
No trends are assessable, no previous data are available for pressures, the condition is variable (some are improving, some unknown) and the response is increasing from a low base.
Since 1996, the pressures on Australia's landscapes have intensified and the condition of Australia's lands continues to deteriorate. The response, however, is gaining momentum, although it is too early to know if this growing response will result in a progressive improvement in land condition.