The changing extent and distribution of vegetation on subantarctic islands is considered to be an environmental indicator that will provide insights into the terrestrial effects of regional climate change.
A long term project has been mapping the extent of vegetation on Heard Island in an effort to document the changes in vegetation over time.
The study is utilising a combination of aerial photographs taken in 1980 and in 1986/87, ground control points surveyed using a global positioning system (GPS) in 2000/01 and 2003/04, oblique aerial photographs from 1987, field-based vegetation maps from 1986/87 and 1987/88 and a 2003 high resolution satellite image showing vegetation in the eastern part of the island.
By digitising the old data and overlaying it on a digital elevation model (DEM) of the island, an accurate map of the vegetation on eastern Heard Island in 1987 has been produced. Once the field data for the same period has been similarly mapped for the remainder of the island, this will provide an invaluable ‘baseline’ for monitoring and comparing current and future changes in vegetation extent and distribution.
Vegetation and landscape change is also being assessed through a wide-scale photo-monitoring study. Several hundred photos taken on the ground in 1987 have been re-taken from the same locations, and will be examined to look for any differences. The photo locations were accurately recorded using global positioning systems (GPS) to allow similar monitoring in the future.