Repeat photography, or rephotography, is an established method for studying landscape change. A big advantage of this technique is that it can provide a record going back decades wherever there is old photographs of scenes which can be relocated. Another advantage is the compelling visual story of change that a time series of photographs can present, for example dramatic images of glaciers retreating. These advantages tend to compensate for the rather limited quantitative data that can be obtained using this method.
While historical rephotography projects document changes in streetscapes, vegetation and landforms using photographs from incidental sources such as old postcards, more recent rephotography projects are intentionally set up with precisely located camera positions (using GPS or marker posts) to capture a baseline photograph and subsequent images.
On Macquarie Island several long-term vegetation monitoring plots provide a detailed record of changes in plant species composition and abundance, but for large parts of the island we have no such data. Aerial photography and satellite images with useful resolution extend back to the late 1980s and early 1990s. To go further back in time we can turn to the relatively old technology of the handheld camera.
Veteran Macquarie Island expeditioners have repeatedly photographed the same scenes over many years resulting in time series photographs which offer an insight into changes in the vegetation and landscape from around 1980 to the present. Around 100 landscape scenes have been systematically rephotographed at various time providing a valuable visual record of change – and stability – in the Subantarctic environment.
My research group is currently analyzing these repeat photographs to build up a story of change over time and space on Macquarie Island.