 Cushion plants have been shown to be a keystone species in the ecosystem in which they occur.For example, "Azorella macquariensis" is the only cushion-forming plant that occurs on Macquarie Island and it plays a vital role in the ecosystem as it makes up the major structural component of feldmark vegetation on the island (Threatened Species Section, 2012).Cushion plants are also often considered "nurse species", as their presence is necessary in order for many other alpine species to become established.