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Title: Impacts of icing events on sub-arctic heathland vegetation
Author: Preece, Catherine
ISNI:       0000 0004 2742 2713
Awarding Body: University of Sheffield
Current Institution: University of Sheffield
Date of Award: 2011
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The Arctic is experiencing large climatic changes, particularly during winter, including warming, rain-on-snow events and increased frequency of freeze-thaw cycles. These changes are predicted to lead to an increase in the frequency of icing events. During these events vegetation can become encased in ice which may damage plants through freezing, hypoxia or high C02 (created within impermeable ice layers) and mechanical injury. To date however, ice encasement impacts on arctic vegetation remain largely unknown. In the study area in sub-arctic Sweden, snow pack surveys verified the occurrence of impermeable ice layers within open and forest dwarf shrub heathland (the dominant vegetation types of the region). Field manipulation experiments were established in these two habitats with icing events simulated in January and March of2008, 2009 and 2010. Impacts of ice encasement on the growth, reproduction, phenology and abundance of four widely distributed dwarf shrub species were determined in the following growing seasons. Additionally, a suite of physiological indicators of damage were monitored including foliar electrolyte leakage, chlorophyll fluorescence and ethanol accumulation. Overall, plants demonstrated an intermediate to high level of tolerance to icing with responses being species-specific. To investigate the relationship between ice encasement and hypoxia and CO2 build-up within ice, a novel field chamber experiment was established, simulating winter-time hypoxic and high CO2 conditions. In this study also, the species showed high tolerance to hypoxia and whilst high CO2 did have some negative impacts, overall effects were rare. This tolerance may therefore provide one explanation for the general tolerance of icing seen in the ice simulation studies. In conclusion, whilst icing events have been shown to have some impacts on sub- arctic dwarf shrubs, community impacts may take many years of repeated icing events to become apparent given the intermediate to high level of tolerance of the plants.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available