The Vegetation of Subantarctic Campbell Island

The vegetation of Campbell Island and its offshore islets was sampled quantitatively at 140 sites. Data from the 134 sites with more than one vascular plant species were subjected to multivariate analysis. Out of a total of 140 indigenous and widespread adventive species known from the island group, 124 vascular species were recorded; 85 non-vascular cryptogams or species aggregates play a major role in the vegetation. Up to 19 factors of the physical environment were recorded or derived for each site. Agglomerative cluster analysis of the vegetation data was used to identify 21 plant communities. These (together with cryptogam associations) include: maritime crusts, turfs, megaherbfields, tussock grasslands, and shrublands; mid-elevation swamps, flushes, bogs, tussock grasslands, shrublands, dwarf forests, and induced meadows; and upland tundra-like tussock grasslands, tall and short turf-herbfields, bogs, flushes, rock-ledge herbfields, and fellfields. Axis 1 of the DCA ordination is largely a soil gradient related to the eutrophying impact of marine spray, sea mammals and birds, and nutrient flushing. Axis 2 is an altitudinal (or thermal) gradient. Axis 3 is related to soil reaction and to different kinds of animal influence on vegetation stature and species richness, and Axis 4 also appears to have fertility and animal associations. Autecological interpretation of the data demonstrates clear niche segregation of congeneric species and species with similar growth forms. The notable megaherbs and giant tussocks may be an adaptation to harvesting nutrients from the aerosol precipitate. Heat harvesting in the cool, cloudy, wet, and windy climate may also be implicated. The history of farming and natural disturbances has resulted in a complex mosaic of vegetation-soil systems of varying maturity. Their putative dynamic interrelationships are depicted in terms of impacts of burning, grazing, marine animals and climate change and subsequent recovery or primary and secondary succession. __________________________________________________________________________________________________________________________________