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.

本地图所用数据源自两项ASAC项目（编号488与956），帕特丽夏·塞尔柯克（Patricia Selkirk）为该项目首席研究员。麦夸里岛（Macquarie Island，南纬54°，东经159°）为亚南极岛屿，长约35千米，宽3至5千米，地处南大洋，位于塔斯马尼亚、新西兰与南极洲之间的大致等距位置。该岛植被以草本为主，无灌木与乔木。本次植被与水系制图基于野外实地观测、卫星影像及少量斜向航空摄影资料，制图比例尺为1:25000。本次植被制图所采用的分类体系，基于植被冠层高度与地表叶盖率（即植被结构）属性，而非物种分布（即植物区系）。植被类别的空间分布与坡向、地形及岩石类型具有显著相关性。沼泽、溪流与湖泊构成了复杂的水系格局，该格局深受太平洋板块与澳大利亚板块边界处构造活跃的麦夸里海岭出露脊部的地质条件影响。全岛水系格局在本次制图中的呈现精度，远高于此前所有同类地图。