Land management

Introduction

Land management refers to the way in which humans use the land, along with the plants and animals living on it, as a resource to fulfil the needs of society. The ways in which humans have utilised the land in Australia - the driest and least fertile inhabited continent of the world - have transformed markedly over the past 200 years.

In contrast to this mode of land management, the European pattern of settling in permanent locations, using the land for agriculture and depleting natural resources for industry (often driven by economics rather than absolute need) was an entirely new concept. While increasing the productivity of the land has brought about economic gains and much richness in terms of food and material goods, vast areas of the Australian landscape have been degraded. Now, unable to rejuvenate, much of our land can no longer be considered a resource.

Key human impacts and resulting environmental concerns

All of the factors discussed below have significantly altered ecosystems and brought about a reduction in native plant and animal populations in Australia. The range of living organisms in an ecosystem is known as biodiversity (refer to Chapter 5 of this topic).

Agriculture and secondary salinity

Agriculture can be defined as the process of cultivating plants and domesticating animals (livestock such as sheep, cattle and pigs) for the production of food and other goods intended for human consumption. Agriculture is one of Australia's most vital national industries. It plays a key role in the nation's economic well being (through exports), as well as the domestic population's well being (through providing food). Australia is now one of the world's largest exporters of farm commodities such as wool, wheat, sugar, cotton and beef.

In terms of its impact on Australia's land, water and biodiversity (range of plant and animal species) agriculture has also been the most environmentally damaging industry, with economic and environmental interests in a perennial state of tension. The European methods of farming, pastoralism (the use of the land to graze livestock) and cropping introduced by early settlers did not suit the hostile climatic conditions of the drought and flood-prone Australian outback. These practices have probably had a more severe impact on the physical environment of Australia than anything else since 1788.

Agriculture is the major cause of Australia's salinity crisis, which is now one of the nation's most pressing environmental concerns. There are two types of salinity that affect Australian landscapes: primary salinity and secondary salinity. Primary salinity occurs as a result of natural processes such as low rainfalls and high levels of evaporation. Australia is naturally prone to this type of salinity in certain areas. Secondary salinity however, is caused by humans using the land in ways that interfere with the natural properties of the soil. Secondary salinity can be classed as either dryland or irrigation salinity.

Land clearing for agriculture

In order to establish an agricultural industry, vast areas of the Australian outback were cleared of their native vegetation. This was so that farmers could create pastures for their sheep and cattle, and fields to grow their crops. The large-scale clearing of forests and bushland has meant that, during periods of heavy rain, more water is able to seep into the ground, which causes water tables to rise. As water tables rise, they bring with them salts that are naturally found deep beneath the surface of the land. This excess salt then accumulates at the surface and increases the salinity of the top soil to unnatural levels, which makes it almost impossible for any remaining vegetation to survive.

As more and more vegetation disappears, this cycle continues and the surface of the land becomes exceptionally dry and infertile. This problem is known as dryland salinity and it has affected millions of hectares of land across Australia. The area most affected by dryland salinity in Australia, and possibly the world's worst example of the problem, is Western Australia's wheatbelt. See animation 1

Land clearing for timber harvesting

Enormous areas of bushland have also been logged (cleared) in many parts of Australia so that the timber can be harvested for wood chipping and the building and construction industries. These processes have also exacerbated Australia's salinity crisis. As with the process of salinity described earlier, logging allows more water to seep into the deeper layers of earth. As water tables creep upwards, salt rises and accumulates at the surface.

The process of logging also exposes top soil and makes the land extremely sensitive to wind and water erosion, particularly during dust storms and periods of heavy rain. Problems associated with water erosion are worse when vegetation is cleared in mountainous regions. This is because when it rains the water begins to flow in channels, which become progressively deeper and larger over time. This process is known as gully erosion. See image 1

Irrigation and the use of chemicals

Another major cause of salinity is the use of river water to irrigate (water) crops and pastures. This is known as irrigation salinity. When water is pumped out of our rivers for these purposes, it absorbs the salts from the soil (which have already accumulated due to rising water tables) and then drains back into the river. The problems this causes for water management will be discussed in the next chapter.

Since the early days of agriculture, farmers began to use chemicals and fertilisers in order to accommodate the harsh Australian soils, which were naturally unsuitable for the cultivation of European-style crops. As dryland salinity caused by land clearing made the problem of infertile soils worse, the use of chemicals became more and more widespread. This then led to the problem of acid soil and toxic soil. During periods of heavy rain, runoff from land where these products had been used began to contaminate our rivers, causing massive algal blooms (build-ups of toxic blue-green algae) - a problem for which Australia unfortunately held the world record during the 1990s. See image 2

Technological advancements in agriculture

In an economic sense, technological advancements throughout the twentieth century have also significantly changed the way the land has been managed in Australia. The creation of monocultures (large areas of a single crop) for example, has been enabled by the use of heavy machinery and sophisticated irrigation technology. While such advancements may have made farming less labour intensive and been economically advantageous in the short-term, they have been environmentally and socially negative. Impacts have included a further reduction in humans' contact and relationship with the land, further degradation of soil composition and structure, and a decrease in employment and population levels in rural areas.

Sustainable agriculture

In order to sustain life we are dependent upon our natural environment for food, water and raw materials. If there is to be any hope of meeting production needs and simultaneously alleviating the range of environmental problems caused by damaging land management practices, land use in Australia will need to shift towards using sustainable methods. In the commercial sector, however, only economically viable initiatives are considered. Pressure to maximise production and increase profit is an issue which influences the nature our agricultural and natural resource industries.

Positively, recent trends show that more sustainable methods of farming and agriculture are experiencing an increase in popularity in Australia. A common example is merging crops and farm animals together in mixed systems. Many farmers now also opt to completely replace synthetic chemicals and fertilisers with natural substitutes such as farmyard manure. This is known as organic farming.

Replacing unsuitable crops with legumes and cereals (which are more suited to Australia's physical environment) has also helped to minimise some of the problems, as has replanting trees in areas that were cleared for agriculture. Although these new approaches have been positive, many of the impacts of land degradation are unfortunately irreversible. Only changes that are environmentally, socially and economically sustainable will have the capacity to reverse this situation.

Genetic engineering in agriculture

Increasingly, although somewhat controversially, genetic engineering (sometimes referred to as biotechnology) is now being used in the Australian agricultural industry, particularly by cotton and canola growers. In 2001 around one-third of all cotton produced in Australia was from GM crops.

There are, however, risks and benefits associated with this trend. Proponents of genetic engineering argue that it could be used to create crop strains that are resistant to pests and weeds, thereby reducing the need for farmers to use toxic chemicals. While this may be true, many farmers and environmentalists are against the use of biotechnology, believing that the potential dangers override the benefits.

An example of a potential advantage of genetic engineering is that increased yields from genetically-modified (GM) crops may mean that less land is cleared to create crop fields and more of the Australian landscape can be revegetated. An example of a potential risk in using GM crops is that varieties engineered to be chemically resistant to certain pests may end up killing non-target species, thereby posing a threat to biodiversity.