Macquarie Island Cushion Plant (Azorella macquariensis)

Mohamed bin Zayed Species project number 11253175

The Royal Tasmanian Botanical Gardens (RTBG) was established in Hobart, Australia, in 1818 and houses the most comprehensive collection of Tasmanian and Macquarie Island plants in the world. The Subantarctic Island Plant House, opened in 2000, is currently the only public collection of subantarctic plants in the world.  The RTBG will partner with the Australian Antarctic Divison and the Biodiversity Conservation Branch of the Tasmanian State Government to conduct this project.

The project will be based on Macquarie Island, a World Hertiage Listed, subantarctic Australian Territory lying north of the Antarctic Convergence in the Tasman Sea and managed by the Tasmanian Government Parks and Wildlife Service.

Macquarie Island is unique in its origin in that it is a very rare example of recently uplifted oceanic crust formed around 11 million years ago. It is the only place on earth where rocks from the earth's mantle are being actively exposed above sea level. Unlike other Subantarctic Islands, there are no active volcanoes or glaciers creating geological deposits on the island meaning its origin is entirely oceanic.

Five plant communities have been identified on the island consisting of grassland, herbfield, fen, bog and feldmark. The vascular flora is small, consisting of 46 species of which four are endemic - Azorella macquariensis, Puccinellia macquariensis (a grass) and two orchid species, Nematoceras dienemus and Nematoceras sulcatum.

A member of the Apiaceae family, Azorella macquariensis is a low growing perennial herb, it forms tight cushions varying in size from a few centimetres to several metres in diameter.  A.macquariensis is a keystone species dominating the feldmark vegetation which occurs at altitudes between 200-400m and covers roughly half the Island.

In December 2008 it was observed by Dr Dana Bergstrom from the Australian Antarctic Division (AAD), that large areas of A.macquariensis were dead or dying back. Since then there has been extensive survey and research work conducted to determine the cause of the dieback which appears to be multifactorial, possibly including a primary or secondary pathogen, and in response to recent changes in the island's weather patterns.

A. macquariensis has been listed as Critically Endangered under the Australian Federal Government Environment Protection and Biodiversity Conservation Act 1999, which draws heavily from the assessment criteria in the IUCN red lists. 

In a review by the World Heritage Commission in 2010 it was recognised that 
A.macquariensis cushions form the main structural component of the feldmark community on Macquarie Island and that the loss of this species would cause severe modification to the Island's ecosystem, possibly leading to major erosion problems and the decline of associated species. The World Heritage Commission recommended that "the State Party urgently determine and address the cause of dieback of the Macquarie cushion plant, create larger ex situ conservation holdings of seeds and living plants, and assess the remaining healthy cushion plants in the summer of 2010" (State of conservation of World Heritage properties WHC-10/34.COM/7B, p. 44)

The Project Objectives are -
• To maintain a secure, long-term ex-situ collection of A. macquariensis on Macquarie Island and to,

•To increase viable holdings of A. macquariensis seed in the RTBG Seed Bank for future recovery programs

The RTBG has held collections of A. macquariensis and related species since 1996, and undertook the care of a small emergency ex-situ collection in 2009. Unfortunately this species has proved difficult to maintain in the long term due to the inability to replicate the extreme environmental conditions required and the costs involved in trying to artificially mimic these conditions. In April 2010 a small experimental trial of 9 potted specimens, with supplementary watering, was set up by the RTBG on Macquarie Island, and have been monitored monthly via photographs taken by field station staff. These plants have continued to grow successfully and this is now considered to be the most effective method of conserving this species, ex-situ, until large quantities of seed can be harvested.  To date seed collection has proved difficult on Macquarie Island due to the extreme weather conditions and the limited range of healthy populations of A. macquariensis from across the Island. To date the RTBG Seed Bank has received approximately 4,000 seeds. A good ex-situ collection is considered to be between 10,000 - 20,000 seeds from multiple populations across the island. The 54 plants that will comprise the ex-situ conservation collection on Macquarie Island will also be used as a "seed orchard", that is, provide a collection of plants that can be hand pollinated to increase seed set and enable easier monitoring and harvesting of seed.

http://rtbg.tas.gov.au/conservation