PLANTS OF MACQUARIE ISLAND
 
Poa foliosa 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  
                    Stilbocarpa polaris
Colobanthus muscoides - showing seed
     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
                     Ranunculus crassipes
Cardamine corymbosa
                         Cardamine corymbosa
 
Luzula crinita  
                     Luzula crinita
Aceana magellanica

                                              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


Update November, 2009
Azorella macquariensis.
In December 2008, a botanist from the Australian Antarctic Division first noticed that more than 90 per cent of this endemic cushion plant had died or is dying. There are a number of possible reasons for this die-back, the first being that the mean temperature has increased by more than half a degree over the past 50 years and the island is drying out and warming up. It is not so much a case of less rain than a change in rain and wind patterns.  This situation is affecting other sub-polar islands around the world.

Secondly there is the over-population of rabbits (since the eradication of feral cats - see above), which are causing a lot of physical damage.  Warmer temperatures has enabled the rabbit kittens to survive.  This problem should be ameliorated when the hunters and their specially trained dogs set their sights on the island in May 2010.

Thirdly a pathogen may be responsible for the plant's plight.

It is now considered to be critically endangered and the Antarctic Division has joined forces with the Royal Tasmanian Botanical Gardens in Hobart,  the DPIPWE (Dept of Primary Industries, Parks, Water and Environment),  Parks and Wildlife,  UTAS (University of Tasmania) and New Town Laboratory to try to save this cushion plant population.  Dr Jenni Whinan, senior ecologist of DPIPWE  fears any  increase in the die-back will bring a new set of environmental concerns including soil erosion, to the island.

Seeds of Azorella macquariensis have been collected for the Millenium Seed Bank and plant material has been set aside for tissue culture testing.  Twenty healthy plants, currently in quarantine, are also to be located at the botanical gardens in Hobart. Work is under way to try and mimic the sub-polar conditions the species needs to survive while in captivity."It is proving very difficult to give the plant the same conditions here", Dr Whinan said. "The lights have been changed in the quarantine area where the plants are housed, along with temperature, and fans are used to try and keep the plants, which normally grow in very exposed conditions, as healthy as we can."

Tight biosecurity measures are in place to ensure any pathogen does not leave the island and cause environmental problems in mainland Tasmania.

Pest Eradication Update 18 April 2010
In an effort to restore environmental damage caused by the excessive rabbit population, special baiting is about to commence. This will be followed in August by the use of hunting dogs which have been especially trained to be “prey specific”, to  protect the general wildlife.
Seed from some of the heavily damaged plant species have been collected and brought back to the Royal Hobart Botanical Gardens, for germination and ultimately used to repair the depleted areas.

Pest Eradication Update #2 27 August 2010
The pest eradication programme, planned for August, when highland areas were to be baited, with follow-up hunting, had to be abandoned due to extremely bad weather.  Some baits, already laid, had the unfortunate effect of poisoning some seabirds.  The programme will be resumed in April 2011.

Pest Eradication Update #3  20 April 2011 (Adapted from a report by Felicity Ogilvie)
Another attempt is underway to try to kill every rabbit, rat and mouse on the island. In 2010 the program had to be stopped because of bad weather, but the staff are heading to the island a lot earlier this year.  There was also some collateral damage last year when native sea birds were killed by the bait. Steps have been taken to prevent that from happening again.  After an extensive review process extra staff are being taken on site to collect the carcasses.   There is one big difference this year - calicivirus has been released this summer which has been enormously successful and has taken out at least 50% of the rabbit population already.  It’s too early to know if the baiting has made any difference to the destruction of the vegetation and the land slips, but early
signs suggest that vegetation could recover extemely quickly once continued browing
by animals ceases. 

Pest Eradication Update #4  26 April 2012. (Adapted from a report by Fiona Breen)

Greenery returns to rabbit-ravaged hills

The arrival of hunting dogs and their handlers, added to the affects of the calicivirus was almost the final straw in the decimation of the rabbits.  The island is already showing a rapid regrowth of plants, especially the endemic cabbage and the tall tussock grass and there is a return of seabirds which are breeding  more successfully since the predatory rats have gone.  Now that poisons are not used to kill the rabbits, the sad loss of seabirds (who died after eating the carcasses) has not recurred.
A new team of six dog handlers, 10 dogs and another group of hunters will keep up the search. Another group of hunters will follow this one in 2014 until every rabbit is caught.

For the many who work and visit this magnificent island there's a real hope that the eradication team will succceed and the island will return to the flora and fauna sanctuary of the past.

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

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