Vegetation Patterns in Relation to Climatic and Endogenous Changes in Wilkes Land, Continental Antarctica

Abstract

1 The Windmill Islands support the best developed terrestrial vegetation in continental Antarctica. The status of the cryptogamic plant communities are examined in relation to the short-term microclimatic fluctuation and long-term climate change of this region since deglaciation 8000-5500 year$ BP. 2 The broad-scale plant patterns in the Windmill Islands suggest an ongoing expansion of lichen-dominated vegetation and a contraction of bryophyte communities to lower lying areas with reliable moisture supply. These vegetation patterns concur with glaciological and geomorphological evidence, which indicate a long-term drying of climate and uplift of the Windmill Islands since the last deglaciation. 3 Analyses of meteorological records show an average lowering of temperature of 0.101?C year-' in this region over the last decade following an earlier rise of about 0.086?C yearI since 1960. 4 There is significant recent interannual climate fluctuation in the Windmill Islands during the years 1991-94 microclimate models estimated that the time available for plant growth varied from 29.7% to 9.8% of the year for mosses and 10.4% to 6.4% of the year for lichens. 5 Despite relatively large environmental shifts, recent vegetation changes in the Windmill Islands appear to be much less drastic than those reported for sub-Antarctic regions reflecting the resilient nature and limited growth opportunities of the continental Antarctic flora. Because of the large interannual climatic variation and the lack of long-term data, the time scale of the plant community changes are very difficult to estimate and therefore the future effects of climate change on these terrestrial Antarctic communities are impossible to predict with confidence.