State of the Environment 2011 (SoE 2011)
State of the Environment 2011 Committee. Australia state of the environment 2011.
Independent report to
the Australian Government Minister for Sustainability, Environment, Water, Population and Communities.
Canberra: DSEWPaC, 2011.
7 Antarctic environment
3.2 Pressures on the terrestrial environment
3.2 Pressures on the terrestrial environment
As for the marine environment, pressures on the terrestrial environment operating on a global scale include anthropogenic climate change (e.g. atmospheric warming and changes to water regimes), while local pressures include the introduction of alien species and impact from human activities.
Climate change impacts in Antarctica and the subantarctic include changes in trends in climate parameters (such as air temperature, precipitation and wind speed), as well as increased frequency and impact of extreme or pulse events.207 Both are regionally specific. In Antarctica, flooding from an extreme summer warming event in 2002 altered species abundances in nematode communities in the Dry Valleys,207 and an extreme warming event in the winter of 2009 negatively impacted moss communities in the Windmill Islands (M Ball, Australian National University, pers. comm., April 2011).
The introduction of alien species has significantly altered the landscape, composition of ecosystems, and species interactions on many subantarctic islands not under Australian jurisdiction.208 Studies of the flora at the French subantarctic Kerguelen Island date back to 1874 when three introduced plants were collected209 Large-scale surveys mainly in the 1970s and 1980s discovered a total of 168 introduced plant species on Possession, Kerguelen and Amsterdam islands. During a survey in 2000, 118 of these were still present. On some islands, the alien species are well established and outnumber the native species. For example, at Kerguelen Island, 68 introduced plant species were present in 2000 compared with only 14 native species.209 In addition, there are 30 known invertebrate alien species.
On Australia's Macquarie Island, there are only 3 alien plant species but 28 alien invertebrate species. Recent research has suggested that the presence of some alien invertebrates has a negative impact on native invertebrate species richness and density.210 Australia's McDonald Island appears to be the only island in the subantarctic that is free of introduced species. Nearby Heard Island has one known alien plant, the grass Poa annua, and three invertebrate species: the earthworm Dendrodrilus rubidus, the mite Tyrophagus putrescentiae and the small thrips Apterothrips apteris,211 but no introduced vertebrates.
Climate change and the intrusion of invasive species may combine as pressures.145,212 As global warming progresses and ambient temperatures rise, non-native species formerly unable to survive in the region may now be capable of establishing themselves and outcompeting the native organisms.145 New species that become established in a warming environment tend to be more competitive than native species because of better dispersal mechanisms or lack of predators, or may occupy niches that previously did not exist. Under such circumstances, food webs and ecosystem functioning could be altered dramatically (e.g. Convoy & Lebouvier213).
| Component | Summary | Assessment grade | Confidence in grade | Confidence in trend | |||
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| Very high impact | High impact | Low impact | Very low impact | ||||
| Changes in ambient temperature | At the Antarctic Peninsula, populations of two native flowering plants are expanding rapidly; similar observations have been made on subantarctic islands where ice-free areas are increasing; composition of plant assemblages may change |
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| Changes in water availability | In East Antarctica, mosses are drying out rapidly due to ice melt and channel run-off away from existing moss beds |
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| Introduction of alien species and pathogens | Invasive species can have a devastating effect on endemic species and communities. The eradication program currently under way at Macquarie Island will have a positive effect on seabird populations Further warming of the atmosphere may help pathogens to become established |
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| Erosion | More ice-free areas are likely to suffer from erosion, especially on subantarctic islands |
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| Pollution | Deposition of solid and liquid wastes can impact both terrestrial and marine communities. Impacts tend to be localised, but pollutants are also received from non-local sources and are likely to contaminate much larger regions |
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| Wildlife disturbance | Increased visitation puts pressure on wildlife populations; with increasing demands to see wildlife, more areas may be visited more frequently and in greater numbers |
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| Physical disturbance and habitat loss | Many human activities significantly alter the natural environment (e.g. stations); visitation can negatively affect habitat through trampling |
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| Recent trends | Improving | Stable | Confidence | Adequate high-quality evidence and high level of consensus |
| Deteriorating | Unclear | Limited evidence or limited consensus | ||
| Evidence and consensus too low to make an assessment | ||||
| Grades | Very low impact: There are few short-term, reversible impacts from this factor | |||
| Low impact: There are transitory impacts from this factor but locally restricted | ||||
| High impact: There are significant impacts from this factor (may be cumulative); impacts are regional and may become irreversible in future | ||||
| Very high impact:There are predicted significant impacts from this factor that are irreversible; impact is regional | ||||
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