The effects of temperature and moisture on CO2 uptake and total resistance to water loss in the antarctic foliose lichen Umbilicaria antarctica

• Published in: New Phytologist
• Main Authors: Harrisson, P.M., Walton, David W.H., Rothery, P.
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: New Phytologist Trust 1989
• Subjects: Botany; Antarctic; The Antarctic; Antarc*; Antarctica
• Online Access: http://nora.nerc.ac.uk/id/eprint/521243/; https://doi.org/10.1111/j.1469-8137.1989.tb02362.x

Maximum net photosynthesis of field‐fresh thalli, illuminated at 200 μmol photons m−2 s−1 (PAR), was attained at 13 °C and 1.10 g g−1 water content. Small but significant rates of photosynthesis were measured at −5.5 °C. Depression of net photosynthesis at high thallus water contents is explained in terms of thallus anatomy. Calculation of evaporative resistance of the thallus by a new method showed a moisture‐dependent response pattern, and was in agreement with direct observations made on other foliose species.