Kappen, L/ Schroeter, B/ Scheidegger, C/ Sommerkorn, M/ Hestmark, G 1996: Cold resistance and metabolic activity of lichens below 0°C. - Advances in Space Research18(12): 119-128. [RLL List # 166 / Rec.# 9786] Keywords: COLD RESISTANCE/ FREEZING/ LOW TEMPERATURE/ PHOTOSYNTHESIS/ POIKILOHYDRIC/ TEMPERATURE/ WATER RELATIONS
Abstract: 9 fig. ["Laboratory measurements show that lichens are extremely tolerant of freezing stress and of low-temperature exposure. Metabolic activity recovered quickly after severe and extended cold treatment. Experimental results demonstrate also that CO2 exchange is already active at around -20°C. The psychrophilic character of polar lichen species is demonstrated by optimum temperatures for net photosynthesis between 0 and 15°C. In situ measurements show that lichens begin photosynthesizing below 0°C if the dry thalli receive fresh snow. The lowest temperature measured in active lichens was -17°C at a continental Antarctic site. The fine structure and the hydration state of photobiont and mycobiont cells were studied by low-temperature scanning electron microscopy (LTSEM) of frozen hydrated specimens."]