Pressures arising from climate change, population, industry and invasive non-native species can compound (see the Interactions between pressures and cumulative impacts section in the Biodiversity chapter). The addition of more pressures reduces the effectiveness of management efforts that target individual pressures, and can lead to a tipping point for ecosystem collapse (Dakos et al. 2019, Bergstrom et al. 2021). For Australia’s land environment, increasing climate change pressures are likely to compound and complicate the impacts of all other pressures such as altered fire regimes (Abram et al. 2021) and invasive species (Webber et al. 2014).
An example of the impact of compounding pressures is the Australian sandalwood tree (see case study: Australian sandalwood – native forest product or threatened species?, in the Plants section in the Overview chapter). Like many old-growth, slow-growing native species, it is affected by combinations of land-use and climate change stressors. Commercial harvest of wild populations has continued, despite only around 10% of their original extent remaining, and it appears that virtually no new trees have emerged in the wild for 60–100 years due to unsuitable establishment conditions (McLellan et al. 2021). Dramatic declines may be overlooked until a population crash becomes unequivocally evident, requiring urgent and reactive responses (e.g. Bayraktarov et al. 2021). Yet often the cascading signs of collapse can be predicted decades earlier from a basic understanding of the biology, ecology, land-use history, and altered climate and disturbance regimes, which may no longer provide the environmental conditions required for the species to persist (Burton et al. 2020). Understanding these cumulative impacts requires long-term detailed studies, combined with integrated monitoring methods (e.g. Lindenmayer & Taylor 2020, Sparrow et al. 2020).
An increasing number of studies are looking at the cumulative and coincident pressures of human modification of the land that directly or indirectly alter or impact natural areas (Kennedy et al. 2019). Kennedy et al. (2019), for example, found that moderately modified ecosystems dominate the terrestrial biosphere and fall within critical land-use thresholds (see also Theobald et al. 2020, Theobald et al. 2021). These and related analyses of the human footprint (e.g. Watson & Venter 2019, Beyer et al. 2020, Grantham et al. 2020, Williams et al. 2020b) highlight regions where proactive spatial planning is needed to maintain biodiversity and ecosystem function before important environmental values are lost.
Climate change is accelerating and exerting pressure on natural and managed systems to adapt, compounded by the interacting and unrelenting pressure of invasive non-native species. Land use in Australia continues to intensify in some regions, though we can expect some areas of deintensification or abandonment as aridity or climate extremes reduce profitability. Competition for land resources in Australia is intensifying at the expense of natural capital, and the legacy of past unsustainable practices or contaminated lands is only minimally abated. Land clearing is still a significant contributor of environmental degradation across many regions of Australia, though is more localised with a shift towards reclearing forest regrowth and potentially increasing pressure on extensive areas of sparse woody vegetation.
Related to United Nations Sustainable Development Goal targets 11.a, 12.4, 13.2, 15.1, 15.2, 15.3, 15.8
Climate change is accelerating and exerting greater pressure on both natural and managed systems to adapt. Ecosystems are deteriorating and many species are in decline, though some are being advantaged. Farming systems are increasingly needing to adapt to changed conditions or diversify as aridity under climate change reduces profitability.
Clearing of relatively natural environments and conversion to more intensive uses are still a significant cause of environmental disturbance across Australia. Land clearing has increased in recent years, particularly in Queensland and New South Wales, and in more localised areas of agricultural or urban development elsewhere. While there is still substantial primary conversion of native vegetation, there has been a greater shift to reclearing or thinning of forest regrowth, with longer-term impacts on land sustainability.
Extensive areas of grazing and cropping are significant land uses that are intensifying in production regions, with a range of potential impacts. There continues to be significant new mine and waste-site developments in conflict with other land uses. The legacy of past mining is still large and there is considerable public concern about unconventional gas developments. Urban and residential uses are replacing high-value agricultural land, and placing multiple-use pressures on remnant natural areas and leading to higher fire frequencies to reduce disaster risk.
The burden of introduced species with potential to become invasive remains high and is increasing, though the rate of increase may have slowed. Most invasive non-native species are associated with intensive land-use zones, but highly invasive transformer species are altering the structure and function of ecosystems even on remote lands in the relatively natural zone.
Australia’s biosecurity arrangements are some of the best in the world and have been partially effective, but new threats continue to emerge.
Progress has been made in developing national approaches to weeds, pests and diseases, and additional resources have been made available.