Distribution and Dynamics of Vegetation in Relation to Natural Disturbance Factors, Heard and McDonald Islands
Metadata record for data expected ASAC Project 423
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From the abstracts of the referenced papers:
Eight species of vascular plants were previously known from subantarctic Heard Island. three additional species, Montia fontana, Ranunculus biternatus and Poa annua, were discovered during the 1986 austral summer. Details of their habitat and known distribution on the island, and their possible means of arrival, are discussed.
The Heard and McDonald Islands are the only subantarctic group which appears to be free of human-introduced animals and plants. Vegetation changes in its species-poor flora are therefore likely to be due to natural factors. Significant glacial recession has exposed new areas for colonisation over the past 40 years. Analysis of vegetation transect data from seven glacier retreat zones and adjacent areas indicates four main patterns of primary colonisation, with moisture availability and effects of animal disturbance being major differentiating environmental factors. Vegetation colonisation can be rapid under the most favourable environmental conditions, for example abundant surface drainage from springs or snow melt with or without effects of nutrient enrichment by animals. It can be expected that with continuing climate amelioration and glacial recession, the size of vegetated areas will expand. Changes in distribution of some vascular plant species around the island have been noted and tentatively linked with climatic warming, and additional changes are predicted. Future effects of changing trends in population numbers of animals utilising and interacting with terrestrial vegetation communities are uncertain. Further changes can now be monitored from recently established reference points.