Plants of Macquarie Island

PLANTS OF MACQUARIE ISLAND

Macquarie Island, now a World Heritage Reserve, is part of Tasmania's territory almost 1500 kilometres southeast of Hobart, and lies just outside of the antarctic convergence (54.5 deg. S, 159 deg. E), where cold water from the southern ocean meets warmer northern waters. Located in a geologically active region notorious for earthquakes, the Island rose about 600,000 years ago, very young geologically speaking, and is a piece of deep ocean crust which was thrust above sea level by massive continental plate activity. It's quite small, 34 kilometres long, 5.5 kilometres wide and up to 433 metres above sea level and is rising at a rate of about 0.5mm per year, but being in the path of the "Furious Fifties", it experiences cool, wet, windy conditions and considerable variation in summer and winter daylight hours. Air temperatures vary only 4 - 4.5 degrees centigrade from mid winter to mid summer. It receives about 1050 mm of precipitation per annum which falls on more than 320 days of the year!

Poa foliosa

Stilbocarpa polaris

Colobanthus muscoides - showing seed

The island was discovered in 1810 when its natural resources were intensively exploited by seekers of abundant animal fur and oil until well into the 1920's. Tragically, the original populations of the fur seal were exterminated within 5 years of its discovery. The introduction of vermin such as rats, cats and rabbits had disastrous effects on the biota. Today the island itself is classed as a Tasmanian Nature Reserve with Tasmanian park management and Tasmanian Rangers but the research station on a narrow isthmus at the northern end is maintained and run by the Commonwealth Antarctic Division and is a successful example of Commonwealth-State co-operation.

                     Ranunculus crassipes
                         Cardamine corymbosa

                     Luzula crinita
                                              Aceana magellanica

The most striking feature of Macquarie Island is the abundance of seabirds - Skuas, Shearwaters, Petrels, Prions, Albatross and of course, penguins - and the mammal fauna, all of which contribute to the nutrients in the soil. As the island has never been connected to an adjacent land mass, all flora and fauna has arrived there via long-distance oceanic dispersal. The flora shows taxonomic linkage to other subantarctic islands, the continents to the west and the islands to the south of New Zealand. Those plants which have managed to reach and successfully colonise the island exhibit a range of strategies for dissemination, reproduction and colonisation. The flora is rarely over 1 m. tall and although not particularly diverse has 45 vascular plant species and 91 species of moss as well as a rich population of liverwort and lichen. The flora is classified as growing in 5 main vegetation formations - grassland, herbfield, fen, bog and feldmark. Three plants - Azorella macquariensis, Puccinellia macquariensis and Corybas dienemus are endemic. Research continues to increase the number of species discovered and reclassified. In 1981 Macquarie Island became a restricted area and collection of scientific specimens requires a permit.
UPDATE 15 July, 2006
Since this item was first presented in 1999/2000 major changes have occurred to the island vegetation. Tasmanian University scientists, Justin Shaw and Jenny Scott, have written a paper showing the devastation by rabbits during the past six years when the last of the feral cats was eradicated. This element, plus the fact that rabbits have developed a natural resistance to myxomatosis, together with a climate change bringing warmer and drier winters, has enabled rabbits to breed successsfully all year round. Until recently, winter breeding was unsuccessful because the kittens would drown or females were too thin to breed.

Pest Eradication Update December 2007
Following the announcement that the Tasmanian and Australian Government would jointly fund the $24.6 million project, Tasmanian Parks & Wildlife Service have announced details of a seven-year project to rid the island of rabbits and rodents. The plan will involve helicopters dropping pellet baits targeting rabbits, rats and mice.

Work now under way includes construction of sixteen 5x5 metre plots protected by rabbit-proof fencing in a bid to protect specific locations of plant species that are under severe pressure. These will complement other existing scientific exclosure plots and prevent reintroduction as rabbits are removed.

Other actions include over-flight trials of helicopters and test baiting around penguin colonies to determine the response of the penguins to these activities. Discussions have also been held with skilled dog trainers. Dogs will have a crucial role in the success of the project, following up the major baiting phase with on-ground hunting of surviving rabbits. The dogs will assist hunters and must be trained to focus on rabbits while avoiding non-target species, in particular native animals More information about the eradication program can be found on Parks and Wildlife Service website www.parks.tas.gov.au

References and acknowledgements
1. Flora of Australia Volume 50, Oceanic Islands 2 . Australian Government
    Publishing Service, Canberra (1993).
2. Subantarctic Macquarie Island.   P M Selkirk, R D Seppelt and D R Selkirk,
    Cambridge University Press (1990).
3. J. R. Croft and M. M. Richardson - Australian National Botanic Gardens, Canberra

The Australian Plants Society would like to thank the Royal Tasmanian Botanical Gardens for their kind co-operation in the preparation of this item.

Special thanks to M. Fountain and M. Brown of the Royal Tasmanian Botanical Gardens, Hobart

SUBANTARCTIC PLANT HOUSE