insulating properties of past growth under the surface of the cushion plants and the peaty soils in which they grow prevents temperatures around the roots dropping below -1 °C, which stops the roots from freezing. Surrounding plants species have adapted to not only benefit, but rely on these conditions the cushion plants provide to survive and grow, and are restricted to habitats in which cushions are present. Threats Three Tasmanian cushion plant species are listed as "under threat": Veronica ciliolata (subspecies fiordensis), Azorella macquariensis and Colobanthus pulvinatus. Tasmanian endemic species, Veronica ciliolata subspecies fiordensis, is listed as vulnerable under both the Threatened Species Protection Act 1995 and the Environment Protection and Biodiversity Conservation Act 1999. The total population of mature individuals is estimated to be from 1500 to 2000. Threats include: Ski field expansion and other inappropriate development of the Ben Lomond plateau, in which the population is restricted, Climate change and an increase in temperatures that may negatively affect this species if suitable alpine habitat within possible dispersal range diminishes Stochastic events including landslides, drought, pathogens and inadvertent damage. The species' low range has made it particularly vulnerable if such events occur. Azorella macquariensis, which is endemic to Macquarie Island, is listed as endangered under the Threatened Species Protection Act 1995 and Critically Endangered under the Environment Protection and Biodiversity Conservation Act 1999. Since 2008, this species has encountered substantial dieback and has had a catastrophic decline in population size. The cause of the dieback is unknown and under investigation. Once dead, the cushions may erode and as a result could have adverse impacts on the rest of feldmark vegetation due to its vital structural role in the ecosystem. Potential factors that threaten Azorella macquariensis include: Feldmark vegetation has been identified to be at risk to a change in climate if temperatures increase, drier soil conditions, less rainfall and increased frosts occur. The introduction of an alien species such as a plant, vertebrate, invertebrate or pathogen, could have detrimental effects on the species, either directly, through infection or competition, or indirectly, through habitat degradation. Colobanthus pulvinatus is listed as rare under the Threatened Species Protection Act 1995. References Cushion plants Flora of Tasmania Flora of Macquarie Island