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Photosynthetic response of the Antarctic moss Polytrichum alpestre Hoppe to low temperatures and freeze-thaw stress

Kennedy, Andrew D.. 1993 Photosynthetic response of the Antarctic moss Polytrichum alpestre Hoppe to low temperatures and freeze-thaw stress. Polar Biology, 13 (4). 271-279. 10.1007/BF00238763

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Abstract/Summary

The effect of low temperatures and freeze-thaw stress on photosynthetic carbon exchange in an Antarctic population of the turf-forming moss species Polytrichum alpestre Hoppe was investigated using infra-red gas analysis. Photosynthetic recovery from freezing was found to depend on the absolute depth of low temperature experienced. Repeated freeze-thaw cycles caused a greater reduction in gross photosynthesis than constant freezing over the same period of time suggesting that the freeze-thaw event itself, and not just cold temperatures, causes damage. The frequency of freeze-thaw events was significant: freeze-thaw cycles every 12 h inflicted more damage than freezethaw cycles every 24 or 48 h. Most damage occurred during the first cycle; relatively little was recorded during subsequent cycles. At +10°C, gross CO2 flux was directly proportional to moss water content between 0.3 and 3.5 g·g−1 dry mass. Moss samples with a low water content withstood freeze-thaw cycles to -5, -10 and-20°C better than samples with a high water content indicating that desiccation in the field may improve survival at low temperatures. Microclimate data for field populations of Polytrichum alpestre at Signy Island suggest that sub-zero temperatures and freeze-thaw stress may act as limiting factors on the species' distribution and viability, particularly when the insulating effect of snow cover is small.

Item Type: Publication - Article
Digital Object Identifier (DOI): 10.1007/BF00238763
Programmes: BAS Programmes > Pre 2000 programme
ISSN: 0722-4060
Date made live: 19 Sep 2017 13:03 +0 (UTC)
URI: http://nora.nerc.ac.uk/id/eprint/517861

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