Old growth cushion plants and mosses on sub-Antarctic Macquarie Island are being decimated by recent climate change. New research that we published in the Journal of Applied Ecology reveals the cushion plants, Azorella macquariensis, estimated to be hundreds of years old, are dying due to windier and drier conditions.
The dieback of the cushion plants and mosses is rapid, progressive and widespread across the island.
Cushion plants have survived for thousands of years on the island but are now struggling to cope with the rapid changes occurring on the Island. Over the past four decades the environment has altered dramatically from wet and misty to one subject to periods of drying.
Our study, undertaken by 18 scientists from 10 institutions, looked at 115 sites across the Macquarie Island alpine tundra. Between 2008 and 2013 we found that 88% of the study areas had dieback present, often leaving a desert-like landscape. The extent of the death of this keystone endemic cushion plant is so severe that it has been declared critically endangered.
We have concluded that the primary cause of the species’ collapse is most likely failure of cushion plants and mosses to withstand changes in summer water availability. For 17 years in a row there was not enough water available to the plants during their summer growing conditions. Additionally, between 1967 and 2011, there has been increases in sunshine hours, wind speed and water loss from the leaves of the plants and soil and this is despite an overall increases in rainfall from storm events. Also some water stressed plants appear to be getting sick with disease.
This rapid ecosystem collapse on Macquarie Island is giving us a window into the potential impact of climate-induced environmental change on vulnerable ecosystems elsewhere.
Healthy plants (above), dying plants (below)
Macquarie Island is a Sub-Antarctic island located in the Southern Ocean, approximately half way between Australia and Antarctica.
It is a Tasmanian State Reserve managed by the Tasmanian Parks and Wildlife Service and was inscribed on the World Heritage List in 1997.
A more detailed account can be read