The vegetation, soil chemistry characteristics and altitudinal distributions of 23 habitats in 7 habitat complexes on sub-Antarctic Marion Island (47°S, 38°E) are described. The habitat complexes (number of habitats in complex) are: Coastal Salt-spray Complex (2); Fellfield Complex (2); Slope Complex (6); Biotic Grassland Complex (3); Biotic Herbfield Complex (3); Mire Complex (6); Polar Desert Complex (1). The habitat classification closely reflects the between-habitat variation in the relative magnitudes of the main forcing variables that determine ecological succession on the island (moisture, exposure, parent soil material, salt-spray and manuring and trampling by seals and seabirds). Hence, it can serve as a framework against which to detect and evaluate ecological responses to the marked climatic change currently occurring in the sub-Antarctic. Suggestions are made on how the habitats might respond to climatic change (warming,drying) and other perturbations (increasing or decreasing influences of salt-spray and manuring).