Forest Vines to Snow Tussocks: The Story of New Zealand Plants
Subalpine and Alpine Communities
Subalpine and Alpine Communities185
Despite its size, the continent of Australia has generally low relief and it is only in the south-east and in Tasmania that mountains rise above treeline. The mountains are not of alpine form, but are basically raised plateaus with fringing scarps. Glaciation was extensive during the Ice Age in Tasmania and as a result there are more steep and rocky sites in the mountains there than on the mainland.
The zone 400–500 m below treeline is occupied by woodland dominated by a few small species of Eucalyptus (Snowgums). In Tasmania there are, in addition, thickets of a shrubby deciduous species of Nothofagus, N. gunnii, which belongs to the N. fusca group. Associated with page 226the Nothofagus are species of Athrotaxis, the only southern hemisphere genus of the conifer family Taxodiaceae.
Frosty valley floors below and above treeline are occupied by a tussock grassland with species of Poa, Danthonia and other genera.
Above treeline, particularly on the mainland, an important plant community is a herbfield of short grasses and such genera as Celmisia, Craspedia and Euphrasia growing on fairly deep, well-drained soils. Below persistent snow patches is an even shorter herbfield with species of Plantago, Neopaxia, Caltha and Ranunculus as in New Zealand. Less common on the mainland, but well developed in Tasmania is a shrubbery on rocky sites comprising genera shared with the heaths of the lowlands.
Poorly drained sites support bogs with Sphagnum moss, a variety of small shrubs, sedges and small species of Astelia. In Tasmania alone cushion bogs with species the same as or related to those of New Zealand are frequent. Species present include Donatia novae-zelandiae and Phyllachne colensoi (shared with New Zealand) and species of Oreobolus and Astelia.
Above snow patches comes a type of fellfield with low species of Coprosma and Colobanthus and, on wind-exposed rounded ridge crests, a different type with, among other genera, Chionohebe and Drapetes, which are also shared with New Zealand. From photographs the latter community looks not unlike the summit plateau fellfield of Macquarie Island.