Contemporary land-use pressures

2016

Grazing

Almost two-thirds of land in Australia has been modified for human uses, primarily grazing of natural vegetation. Livestock grazing accounts for 82 per cent of the area of land used in agriculture, more than one-third of which is in Queensland (ABS 2016c). Environmental issues associated with sheep and cattle grazing include habitat loss, surface soil loss, salinity, and soil and water quality issues. Grazing pressures can also result from feral and native animals, such as goats, camels, rabbits and kangaroos.

Use of grazing land showed a slight decline from 2013–14 to 2014–15 of about 7 per cent; more than one-quarter of this reduction was a reduction in grazing of improved pastures (ABS 2016c). The size of the national cattle herd also declined (Thomas 2016).

Agriculture

Cultivation

Cultivation can benefit agriculture by controlling weeds and pests, and by creating suitably sized soil aggregates for a good seed bed. However, cultivation also disrupts microbiological activity and causes oxidation of organic matter. Its effect on soil organisms and organic matter has been likened to a fire through ploughed soil: cultivation causes a decline in organic matter, which can lead to a general loss of fertility, unless counteracted by actions such as using fertilisers and rotating crops or pastures to restore organic matter levels. Loss of organic matter often leads to soil structural problems, such as surface sealing and hard-setting. Excessive cultivation was widespread during the first half of the 20th century, and still remains a problem in some locations.

Conservation agriculture is a set of soil management practices that minimise the disruption of the soil’s structure, composition and biodiversity. During recent decades, techniques of conservation agriculture have been developed that emphasise retention of crop residues, appropriate rotations with legumes and reduced tillage, or even no tillage. In these systems, seed is drilled directly into the soil, minimising disturbance of soil structure and biota, oxidation of organic matter and the threat of erosion. Maintaining soil cover on sloping land is especially important to protect against erosive rainfall. These changes have a major influence on soil condition and trend. Although declines in uptake of conservation agriculture (e.g. direct drilling) have been reported (Darbas et al. 2013), in some jurisdictions the proportion of cropping land sown using no-till methods increased from 16 per cent in 1999 to 67 per cent in 2013.

Nutrient management

Continuous dryland cropping increases run-off and causes erosion, and long-fallowing dryland cropping contributes to rising watertables. Irrigated agriculture also contributes to rising salinity levels, with run-off of sediments, nutrients and pesticides. Maintaining vegetation in riparian zones helps to reduce nutrient run-off, trap sediments and reduce erosion, particularly erosion due to summer rainfall (Darbas et al. 2013). There is also some data to suggest that wetlands have a role in sequestering nutrients from water, although this may involve accumulation in wetland soils, with the potential for remobilisation during flood events (McJannet et al. 2012).

Conservation agriculture practices have the potential to improve crop yields while maintaining soil ecological health. The minimum-tillage and direct-drilling practices of conservation agriculture, which reduce water erosion through minimal disruption of soil, are widely practised across central and southern New South Wales, south-eastern South Australia, Victoria and Tasmania (Peterson et al. 2014). Nationally in 2014–15, the most common land cultivation practice for crops and pasture was ‘zero or minimum till’ (i.e. no cultivation apart from sowing). Of the pasture land cultivated, 2.3 million hectares received no cultivation apart from sowing, and, of the crop land cultivated, 12.4 million hectares received no cultivation apart from sowing. The use of 3 or more cultivations was the least reported cultivation practice in 2014–15 and had the largest decrease of all cultivation practices, falling by 31 per cent to 660,000 hectares since 2013–14 (ABS 2016c).

The most common crop residue management practice reported in 2014–15 was for standing residue to be retained, which was undertaken on 7.4 million hectares of crops. This practice was followed by residue retained on the ground and residue grazed off, with each reported to be used on 4.8 million hectares of crops. There was a 16.7 per cent decrease in stubble being incorporated into the soil and a 3.5 per cent decrease in stubble being removed by hot burn in 2014–15 compared with 2013–14.

Rates of adoption of conservation agriculture have decreased in the Queensland Murray–Darling Basin catchments, in part as a result of reduced soil extension services, unclear profitability and, possibly, costs of practices. Similarly, although understanding of the farming practices that result in soil erosion and salinity is high in the New South Wales Murray–Darling Basin, adoption of conservation agriculture is low and sometimes decreasing (Darbas et al. 2013).

Production forestry

Industrial plantations are typically made up of single species, often exotic to the region. They have a range of impacts on the environment, from altering local biodiversity to changing soil chemistry to increasing erosion during harvesting and planting. The more extensive native forest production estates (forests available and suitable for commercial wood production) rely on selective harvest of target species. They arouse controversy mainly because of their interruption of ecosystem processes that are critical to some species—for example, selective harvest of mature trees will reduce the population of overmature, and subsequently dying and dead, trees, which are critical in providing large nesting hollows for some birds and marsupials, as well as providing habitat for wood-boring invertebrates and their larvae.

Industrial plantation forests cover 2 million hectares, and native forest production estates cover 36.6 million hectares, 7.5 million of which are public, and 29.1 million of which are leasehold and private (ABARES 2014). It should be noted that the most significant source of native forest wood products is the public multiple-use forests.

Urban and rural residential use

As our population grows and expectations for a higher standard of living increase, urban encroachment continues to cause an iterative loss of strategically valuable agricultural lands in local government areas across most states and territories. Various policies and planning mechanisms are now in place to protect and maintain remaining areas, with all states and territories having specific legislation to enable spatial land-use planning. However, there is ongoing pressure for the sale of agricultural land and consequently an increase in land-use conflicts at the peri-urban boundary. Urban and peri-urban expansion into greenfield sites has an impact on high-value agricultural floodplains around our non–capital cities. As demand for agricultural products increases and there is growing recognition of the need to address the issue of urban encroachment on agricultural land, some jurisdictions are imposing tighter controls on land releases. For example, Tasmania has a State Policy on the Protection of Agricultural Land (2009), which aims to conserve and protect agricultural land so that it remains available for the sustainable use and development of agriculture, recognising the particular importance of prime agricultural land.

Horticultural areas are often located near large urban centres for access to markets and distribution hubs. Encroachment of peri-urban development on horticultural areas can result in pressure on growers to change or cease farming practices that cause odour, noise or dust. Peri-urban areas can also host pests and diseases, posing a biosecurity risk to enterprises.

Local government zoning to prevent such issues may mean that horticultural areas are rezoned as rural, which can limit land value (Horticulture Australia 2006).

Mining

Australia has a significant mining industry, with the sector contributing 8 per cent of gross domestic product in 2012—the fourth largest single sector (ABS 2012a). Although 2014–15 was a period of significant downturn, mining is still a major industry in many regions, particularly in Western Australia, Queensland and New South Wales.

Environmental management in the mining industry before the 1970s was inadequate, and the legacy included contaminated and degraded land with chronic environmental problems. There are also an estimated 50,000 abandoned mines on public and private land in Australia, ranging from single shafts to large complexes (Unger et al. 2015). Inadequate resources are available to rehabilitate them all.

Environmental impacts are now more actively managed, as a result of tighter environmental regulation and the need for companies to obtain a ‘social licence to operate’—this is the set of demands and expectations held by local stakeholders and broader society for how the industry should operate. However, the industry is still rapidly expanding, and the scale of disturbance in some regions is transforming the landscape and causing profound environmental change. Recent controversial approvals for expansion of mining in the Galilee Basin in Queensland and the Hunter Valley in New South Wales had been challenged, in part on the basis of their environmental impacts, including on-ground impacts, air pollution, greenhouse gas emissions associated with combustion and, for the Galilee Basin, the potential risks of contamination of the Great Barrier Reef as a result of shipping from the Abbott Point Terminal.

Unconventional gas—coal-seam gas (CSG), shale gas and tight gas—offers significant current and future energy resources, with CSG, in particular, being developed in the major coal basins of eastern Australia. Although the footprint of individual wells may be limited, concern has been raised that, in the Bowen and Surat basins in Queensland, which contain almost two-thirds of Australia’s known CSG reserves, the impact of CSG development will add to existing ecologically threatening processes—such as fragmentation, clearing, increased invasive species and changed fire regimes—in a region that is already highly disturbed (Ponce Reyes et al. 2016). Such concern about cumulative impacts has led to consideration of regional planning initiatives to ensure strategic and coordinated approaches to both development and monitoring of impacts (WA EPA 2014). The $60 billion already invested in infrastructure to facilitate exploitation in Queensland has also triggered significant regulatory change, both to ensure safe operation and to meet public concern about the environmental and social impact of the industry (Towler et al. 2016).

Waste disposal and contamination

Burying waste has been the most common form of waste management in Australia since urban incineration was phased out in the 1940s and 1950s. Since the 1990s, the siting, design and operation of landfill sites have faced tightening environmental regulation and economic pressures. As a result, the number of active landfill sites has been reduced, their average size has grown, and they are increasingly owned and operated by large private companies. Nearly 500 landfill sites are reported across mainland Australia and Tasmania (Pickin 2013).

From 1997 to 2012, the population of Australia increased by 22 per cent, gross value added (the value of goods and services produced in an area, industry or sector) increased by 64 per cent, and waste generation increased by 145 per cent (ABS 2013; Figure LAN11). During 2009–10, 53.7 million tonnes of waste were generated within the Australian economy. The largest contributor to this total was the construction industry, which produced more than 16.5 million tonnes, much of it masonry. The estimated 8.4 million households in Australia produced about 1.5 tonnes of waste each, totalling 12.4 million tonnes. Nearly half of all waste from households was organic waste, and almost a quarter was paper and cardboard waste. Of the total waste generated in 2009–10, 25.2 million tonnes were recovered domestically, 24.9 million tonnes were disposed of to landfill, and 3.7 million tonnes were exported (ABS 2013; Figure LAN12).

The provision of kerbside recycling schemes helped 97 per cent of households to recycle paper and cardboard, glass, plastic bottles or containers, and aluminium or steel cans. The volume of recovered paper increased from 2.0 million tonnes in 2003–04 to 3.1 million tonnes in 2013–14, which reflects an increased recovery rate, from 48.5 per cent of the paper products consumed in 2003–04 to 87.4 per cent in 2013–14 (ABARES 2014).

New initiatives are seeking to combat the environmental and economic cost of sending materials to landfill. For example, it is estimated that every tonne of expanded polystyrene that goes to landfill costs the owner $1500 to $2500. In response, the New South Wales Government has initiated a series of grants to purchase compactors, shredders and storage cages; the resultant polystyrene blocks are sufficiently valuable to make transport to Sydney for resale financially viable (DoE 2014b).

soe2016_lan_fig12_ABS_infographic_on_waste_generation_and_treatment.png

An image showing the disposal and recovery pathways taken during treatment of the 53.7 million tonnes of waste generated and imports from 2009 to 2012. The different sources and destinations of waste, and the amounts, are explained in the main text. Nearly half of all waste ended up in landfill, with the remainder mostly recovered and a small amount exported.

Source: ABS (2013)

Figure LAN12 Waste generated and waste services provided, 2009–12

Nature conservation reserves, other protected areas, minimal-use land and Indigenous land

The principal pressures on the environmental values of land under conservation, land not formally protected but subject to minimal use, and land formally owned and managed by Indigenous Australians are grazing by pest animals, grazing by domestic livestock (on those tenures where it is allowed), weed infestation, altered fire regimes and, in the longer term, changed climatic patterns. These pressures are discussed in their relevant sections and in the Drivers report.

About 7 million hectares of agricultural land are set aside for conservation or protection purposes, although this fell by nearly 20 per cent in 2014–15 compared with 2013–14 (ABS 2016c). 

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Metcalfe D, Bui E (2016). Land: Contemporary land-use pressures. In: Australia state of the environment 2016, Australian Government Department of the Environment and Energy, Canberra, https://soe.environment.gov.au/theme/land/topic/2016/contemporary-land-use-pressures, DOI 10.4226/94/58b6585f94911