VEGETATION PATTERNS IN RELATION TO CLIMATIC AND ENDOGENOUS CHANGES INWILKES-LAND, CONTINENTAL ANTARCTICA

1 The Windmill Islands support the best developed terrestrial vegetati on in continental Antarctica. The status of the cryptogamic plant comm unities are examined in relation to the short-term microclimatic fluct uation and long-term climate change of this region since deglaciation 8000-5500 years sp. 2 The broad-scale plant patterns in the Windmill I slands suggest an ongoing expansion of lichen-dominated vegetation and a contraction of bryophyte communities to lower lying areas with reli able moisture supply. These vegetation patterns concur with glaciologi cal and geomorphological evidence, which indicate a long-term drying o f climate and uplift of the Windmill Islands since the last deglaciati on. 3 Analyses of meteorological records show an average lowering of t emperature of 0.101 degrees C year(-1) in this region over the last de cade following an earlier rise of about 0.086 degrees C year(-1) since 1960. 4 There is significant recent interannual climate fluctuation i n the Windmill Islands during the years 1991-94 microclimate models es timated that the time available for plant growth varied from 29.7% to 9.8% of the year for mosses and 10.3% to 6.4% of the year for lichens. 5 Despite relatively large environmental shifts, recent vegetation ch anges in the Windmill Islands appear to be much less drastic than thos e reported for sub-Antarctic regions reflecting the resilient nature a nd limited growth opportunities of the continental Antarctic flora. Be cause of the large interannual climatic variation and the lack of long -term data, the time scale of the plant community changes are very dif ficult to estimate and therefore the future effects of climate change on these terrestrial Antarctic communities are impossible to predict w ith confidence.