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Photosynthetic responses of three common mosses from continental Antarctica

Published online by Cambridge University Press:  17 August 2005

STEFAN PANNEWITZ
Affiliation:
Botanisches Institut, Christian-Albrechts-Universität Kiel, Olshausenstr. 40, D-24098 Kiel, Germany
T.G. ALLAN GREEN
Affiliation:
Biological Sciences, University of Waikato, Private Bag 3105, Hamilton, New Zealand
KADMIEL MAYSEK
Affiliation:
Dept. of Environmental Sciences and Energy Research, Weizmann Institute of Science, Rehovot 76100, Israel
MARK SCHLENSOG
Affiliation:
Biological Sciences, University of Waikato, Private Bag 3105, Hamilton, New Zealand
ROD SEPPELT
Affiliation:
Australian Antarctic Programme, Channel Highway, Kingston, TAS 7050, Australia
LEOPOLDO G. SANCHO
Affiliation:
Dep. Biologia Vegetal II, Fac. De Farmacia, Universidad Complutense, ES-28040 Madrid, Spain
ROMAN TÜRK
Affiliation:
Institut für Pflanzenphysiologie, Paris Lodron University Salzburg, Hellbrunnerstr. 34, A-5020 Salzburg, Austria
BURKHARD SCHROETER
Affiliation:
Botanisches Institut, Christian-Albrechts-Universität Kiel, Olshausenstr. 40, D-24098 Kiel, Germany

Abstract

Predicting the effects of climate change on Antarctic terrestrial vegetation requires a better knowledge of the ecophysiology of common moss species. In this paper we provide a comprehensive matrix for photosynthesis and major environmental parameters for three dominant Antarctic moss species (Bryum subrotundifolium, B. pseudotriquetrum and Ceratodon purpureus). Using locations in southern Victoria Land, (Granite Harbour, 77°S) and northern Victoria Land (Cape Hallett, 72°S) we determined the responses of net photosynthesis and dark respiration to thallus water content, thallus temperature, photosynthetic photon flux densities and CO2 concentration over several summer seasons. The studies also included microclimate recordings at all sites where the research was carried out in field laboratories. Plant temperature was influenced predominantly by the water regime at the site with dry mosses being warmer. Optimal temperatures for net photosynthesis were 13.7°C, 12.0°C and 6.6°C for B. subrotundifolium, B. pseudotriquetrum and C. purpureus, respectively and fall within the known range for Antarctic mosses. Maximal net photosynthesis at 10°C ranked as B. subrotundifolium > B. pseudotriquetrum > C. purpureus. Net photosynthesis was strongly depressed at subzero temperatures but was substantial at 0°C. Net photosynthesis of the mosses was not saturated by light at optimal water content and thallus temperature. Response of net photosynthesis to increase in water content was as expected for mosses although B. subrotundifolium showed a large depression (60%) at the highest hydrations. Net photosynthesis of both B. subrotundifolium and B. pseudotriquetrum showed a large response to increase in CO2 concentration and this rose with increase in temperature; saturation was not reached for B. pseudotriquetrum at 20°C. There was a high level of variability for species at the same sites in different years and between different locations. This was substantial enough to make prediction of the effects of climate change very difficult at the moment.

Type
Research Article
Copyright
© Antarctic Science Ltd 2005

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