EXPOSURE AND NUTRIENTS AS DELIMITERS OF LICHEN COMMUNITIES IN CONTINENTAL ANTARCTICA

Lichens dominate the terrestrial vegetation of the ice-free regions of continental Antarctica. Vegetation patterns were studied in the Windm ill Islands Oasis, Wilkes Land, continental Antarctica, in relation to edaphic features to elucidate the factors that govern lichen distribu tion and abundance. Vegetation was studied on a low rounded knell on C lark Peninsula some 3 km North East of the present Casey station. Subs tratum nutrient levels vary considerably across the knell due to the p resence of an abandoned penguin rookery on the crest and the uneven to pography provides both sheltered and exposed sites. Along a 130 m-long transect crossing the knoll from South to North, a total of 25 specie s of lichen and one moss were identified, the vegetation being dominat ed by Umbilicaria decussata, Pseudephebe minuscula, Usnea sphacelata a nd U. antarctica. TWINSPAN analysis of species distributions identifie d six sociations, the distribution of which were related to substratum structure and chemistry. Several species were restricted to nutrient- rich zones while late-lying snow restricted all species to varying deg rees. (C) 1995 The British Lichen Society