Bursts of CO2 released during freezing offer a new perspective on avoidance of winter embolism in trees |
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| Authors: | A Lintunen L Lindfors P Kolari E Juurola E Nikinmaa T H?ltt? |
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| Institution: | 1Department of Forest Sciences, University of Helsinki, Post Office Box 27, FI-00014, Helsinki, Finland;2Department of Physics, University of Helsinki, Post Office Box 64, FI-00014, Helsinki, Finland |
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| Abstract: | MethodsCO2 efflux measurements were conducted during freezing experiments for saplings of three Scots pine (Pinus sylvestris) and three Norway spruce (Picea abies) trees under laboratory conditions, and the magnitudes of the freezing-related bursts of CO2 released from the stems were analysed using a previously published mechanistic model of CO2 production, storage, diffusion and efflux from a tree stem. The freezing-related bursts of CO2 released from a mature Scots pine tree growing in field conditions were also measured and analysed.ConclusionsAll gases dissolved in the xylem sap are not trapped within the ice in the stem during freezing, as has previously been assumed, thus adding a new dimension to the understanding of winter embolism formation. The conduit water volume not only determines the volume of bubbles formed during freezing, but also the efficiency of gas efflux out of the conduit during the freezing process. |
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| Keywords: | Bubble formation cavitation CO2 efflux freezing propagation Norway spruce Picea abies Pinus sylvestris Scots pine winter embolism wood respiration |
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