Humans have both direct and indirect effects on biodiversity. Direct effects mainly involve taking species (e.g. taking animals and plants as food, harvesting plants for ornamental purposes, or removing plants or animals that have become pests). Indirect effects happen as a result of other activities associated with human existence, such as growing food, using industrial processes that either consume natural resources or introduce heat or chemicals into the environment, and clearing land for urban development, agriculture, mining or other activities.

Harvesting of species

Since European settlement, harvesting has had major detrimental effects on many terrestrial species, including red cedar, koalas, and various kangaroos and wallabies. Harvesting of fish and other species are issues in inland water and marine environments (see Chapter 4: Inland water and Chapter 6: Marine environment). Forestry and firewood collection are discussed in Chapter 5: Land. Salvage logging (logging of trees after wildfires) is partly a harvesting issue and partly a habitat modification issue. It has major effects on wildlife, especially species that live in tree hollows.^95-96

Harvesting of native terrestrial species—such as kangaroos, wildflowers or marine species—is strictly regulated (Box 8.4). Illegal harvesting of some species, such as orchids, is frequently mentioned as a threat in species listing. In some cases, harvesting is used as a tool to manage populations of native species that are becoming pests due to changes in their environment that remove previous restrictions on population size.³⁴

Pressures related to population size and lifestyles

Various measures of a society’s ecological footprint, the amount of natural resources consumed by people and the area of land required to support that consumption are available; one of these is the Global Footprint Network (Figure 8.13). In the most recent data, Australia ranks as having the eighth largest ecological footprint of all nations. It is difficult to translate this into an effect on biodiversity, partly because the land from which Australians obtain their resources is not all within Australia, partly because people in other countries obtain their resources from Australia, and partly because the calculations do not reveal in detail which resources are being taken from which ecosystems and which species are being affected. Nevertheless, there is a strong message that lifestyles of Australians are exerting relatively strong pressures on ecosystems compared with people in many other countries.

In another international comparison, based on a set of measures of environmental degradation, Australia had the ninth worst absolute environmental impact out of 171 countries.¹⁰⁰

More than a decade of research using CSIRO’s Australian Stocks and Flows Framework, together with ecological footprint analysis and local-scale modelling, emphasises the importance for all Australian cities of managing not only population growth, but where and how people live, and the consumption of natural resources per person.⁵⁶ This research suggests, for example, that Sydney will have trouble avoiding further losses of biodiversity, because growth will require conversion of relatively undegraded habitat. However, Perth and Melbourne have the scope to minimise losses, because they can develop previously cleared areas where the major effects on biodiversity have already been felt.

Australia’s high footprint is largely caused by our lifestyles, which use high levels of natural resources in an inefficient way. In the Northern Territory, for example, the average ecological footprint of the Indigenous population is 6.4 global hectares per person, while the footprint for the non-Indigenous population is around 9 global hectares per person.¹⁰¹ (Global hectares are a measure of biocapacity—one global hectare is an average of all hectare measurements of biologically productive areas on Earth.) These analyses were based on various data sources from 1998 to 2004. The lower footprint of the Indigenous population is partly due to traditional use of ecosystem resources, but it is also due to poverty.

Consumption of water

Use of inland water for agricultural and other purposes is considered in detail in Chapter 4: Inland water. Here we summarise key points in relation to biodiversity.

Water is extracted from the environment by households and businesses and in agricultural and other production industries for a range of purposes, including direct consumption by humans (e.g. drinking, cooking) and indirect consumption (e.g. use in production of food, manufacturing of goods that contain water or rely on inputs that use water, cooling systems, transport).¹⁰²

Extraction of water from the environment places pressures on biodiversity by affecting flow rates in waterways, which affects the habitat for plants and animals living in those waterways, as well as the wetting and drying cycles that are important for many species’ breeding. It also affects the provision of food for waterway-dependent species. Indirect pressures include effects on hydrological cycles, which affect the levels and condition of underground water on which many species of plants and animals depend. The condition of soils is affected when rising watertables bring salt to the surface. Water consumption is considered in the analyses of ecological footprints.

Australia’s water consumption was 14 101 gigalitres in 2008–09, a decrease of 25% from 2004–05. Agricultural activities accounted for 7589 gigalitres or 54% of total Australian water consumption in 2008–09. This is a decrease from 2004–05 when it was 65% of water consumption, reflecting restricted supplies during southern Australia’s extended drought.

The major impacts of water consumption, changed flow regimes and changed hydrology are on wetlands and the species that depend on them, on animals and plants that live in and around waterways, and in some cases on the landscape more broadly. These impacts are discussed further in Chapter 4: Inland water and Chapter 5: Land.