Satellite imagery for change detection in the sub-Antarctic: using Heard Island as a proof of concept

Heard Island is a pristine and remote volcanic sub-Antarctic island in the Southern Ocean, south of the Antarctic Polar Frontal Zone (APFZ). Heard Island arguably provides one of the most rapidly changing environments for plant growth in the sub-Antarctic region, due to extensive and rapid glacial retreat which has been accelerated by rising temperatures. There has been minimal human impact on the ecosystem of Heard Island, but warmer conditions will increase the ease for invasion of new species. Its location, climate conditions, and pristine nature make Heard Island an ideal site to study the regional effects of climate change. Up-to-date and accurate spatial information on vegetation is of crucial importance to manage this World Heritage Area and to study its changes. During previous expeditions to Heard Island in 1987/1988 and 2003/2004 terrestrial plant ecology has been studied and vegetation maps have been produced from field samples and aerial photography. These field surveys are expensive, labour intensive, potentially intrusive, and often only cover small areas. Because of the island's remoteness and harsh environment, satellite imagery provides advanced and cost-effective means to map its vegetation cover and to quantify vegetation changes.