Life form and water source interact to determine active time and environment in cryptogams: an example from the maritime Antarctic

Antarctica, with its almost pristine conditions and relatively simple vegetation, offers excellent opportunities to investigate the influence of environmental factors on species performance, such information being crucial if the effects of possible climate change are to be understood. Antarctic vege...

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Bibliographic Details
Published in:Oecologia 2013-09, Vol.173 (1), p.59-72
Main Authors: Schlensog, Mark, Green, T. G. Allan, Schroeter, Burkhard
Format: Article
Language:English
Subjects:
Animal and plant ecology
Animal, plant and microbial ecology
Antarctic Regions
Biological and medical sciences
Biological monitoring
Biomedical and Life Sciences
Bryophyta - metabolism
Bryophyta - physiology
Bryophytes
Chlorophyll
Chlorophyll - metabolism
Climate Change
Climatology. Bioclimatology. Climate change
Cryptogams
Earth, ocean, space
Ecology
Ecosystem
Exact sciences and technology
External geophysics
Fluorescence
Fundamental and applied biological sciences. Psychology
General aspects
Global temperature changes
Hydrology/Water Resources
Lichens
Lichens - metabolism
Lichens - physiology
Life Sciences
Meteorology
Microclimate
Mosses
Photosynthesis
PHYSIOLOGICAL ECOLOGY
Physiological ecology - Original research
Plant Sciences
Plants
Precipitation
Sea water ecosystems
Synecology
Temperature
Thallus
Time Factors
Vegetation
Water
Water - metabolism
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Summary:Antarctica, with its almost pristine conditions and relatively simple vegetation, offers excellent opportunities to investigate the influence of environmental factors on species performance, such information being crucial if the effects of possible climate change are to be understood. Antarctic vegetation is mainly cryptogamic. Cryptogams are poikilohydric and are only metabolically and photo-synthetically active when hydrated. Activity patterns of the main life forms present, bryophytes (10 species, ecto- and endohydric), lichens (5 species) and phanerogams (2 species), were monitored for 21 days using chlorophyll a fluorescence as an indicator of metabolic activity and, therefore, of water regime at a mesic (hydration by meltwater) and a xeric (hydration by precipitation) site on Léonie Island/West Antarctic Peninsula (67°36′S). Length of activity depended mainly on site and form of hydration. Plants at the mesic site that were hydrated by meltwater were active for long periods, up to 100 % of the measurement period, whilst activity was much shorter at the xeric site where hydration was entirely by precipitation. There were also differences due to life form, with phanerogams and mesic bryophytes being most active and lichens generally much less so. The length of the active period for lichens was longer than in continental Antarctica but shorter than in the more northern Antarctic Peninsula. Light intensity when hydrated was positively related to the length of the active period. High activity species were strongly coupled to the incident light whilst low activity species were active under lower light levels and essentially uncoupled from incident light. Temperatures were little different between sites and also almost identical to temperatures, when active, for lichens in continental and peninsular Antarctica. Gradients in vegetation cover and growth rates across Antarctica are, therefore, not likely to be due to differences in temperature but more likely to the length of the hydrated (active) period. The strong effect on activity of the mode of hydration and the life form, plus the uncoupling from incident light for less active species, all make modelling of vegetation change with climate a more difficult exercise.
ISSN:0029-8549
1432-1939
DOI:10.1007/s00442-013-2608-9