Macquarie Island Vegetation and Drainage Structure Data Set

The data for this map were collected as part of two ASAC projects - 488 and 956, of which Patricia Selkirk was the chief investigator. Macquarie Island (54 degrees S 159 degrees E) is a subantarctic island (c. 35km by 3 to 5km) approximately equidistant between Tasmania, New Zealand and Antarctica in the Southern Ocean. The vegetation is herbaceous, lacking shrubs and trees. Vegetation and drainage are mapped at a scale of 1:25 000 from field observations, satellite imagery and limited oblique and aerial photography. The categories adopted for mapping vegetation are based on attributes of foliage height and percentage foliage cover of the ground surface (vegetation structure), not on species distribution (floristics). The distribution of vegetation categories is strongly correlated with aspect, topography and rock type. Mires, streams and lakes form an intricate drainage pattern that is strongly influenced by the geology of this tectonically active emergent crest of the submarine Macquarie Ridge at the boundary of the Pacific and Australian plates. The drainage pattern of the whole island is represented in a map with substantially greater accuracy than in any previous map.