Impacts of increased water and nitrogen availability on photosynthesis of the continental Antarctic lichen Usnea sphacelata

TL;DRAbstract

Water availability and low temperatures are believed to be the main ecological limits for continental Antarctic lichens. Lichen growth may also be limited by nitrogen availability. Thallus nitrogen content of two dominant Antarctic macro lichens decreases significantly at the onset of the summer snow melt, but the causes are unknown. Over the past 40 years precipitation rates have increased in the Windmill Islands region of continental Antarctica. An increase in snow fall may result in lichens being wet for longer periods during the summer, which may result in an increase in photosynthetic activity. Should lichen growth be limited by nitrogen availability, however, increases in growth due to increased precipitation may increase the demand for nitrogen beyond supply. Consequently, this may affect long term lichen survival. Usnea sphacelata is the dominant terrestrial macrolichen of continental Antarctica. In order to examine the impact of increased precipitation, in situ stands of U sph

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