title: Chlorophyll a fluorescence and CO2exchange of Umbilicaria aprina under extreme light stress in the cold.
abstract: A lichen growing in a continental Antarctic region with low temperatures and strong irradiance in summer was investigated for evidence of photoinhibition. Field experiments with Umbilicaria aprina from a sheltered site with heavy snowpack showed no effects of photoinhibition when the lichen was exposed to strong sun irradiance for nearly 11 h a day. This was evident from CO2exchange and simultaneous chlorophyll a fluorescence measurements. CO2exchange was also not affected if quartz glass allowing greater UV penetration, was used as a lid for the cuvette. The dependency of net photosynthesis on photosynthetic photon flux density suggests that the lichen is photophilous.
authors.affiliation: Botanisches Institut, Olshausenstrasse 40, D-24098 Kiel Germany, , , , , , DE.
authors.forename: L
authors.initials: L
authors.lastname: Kappen
authors.affiliation: Botanisches Institut, Olshausenstrasse 40, D-24098 Kiel Germany, , , , , , DE.
authors.forename: B
authors.initials: B
authors.lastname: Schroeter
authors.affiliation: Biological Sciences, University of Waikato, Hamilton, New Zealand, , , , , , NZ.
authors.forename: T G A
authors.initials: TG
authors.lastname: Green
authors.affiliation: Australian Antarctic Division, Kingston, Tasmania, Australia, , , , , , AU.
authors.forename: R D
authors.initials: RD
authors.lastname: Seppelt
keywords: CO2 exchange; Chlorophyll a fluorescence; Key wordsUmbilicaria aprina; Low temperatures; Photoinhibition