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Literature » Ultrasonic acoustic emissions in drought-stressed trees - more than signals from cavitation?
Ultrasonic acoustic emissions in drought-stressed trees - more than signals from cavitation?
| Publication Type: | Journal Article |
| Year of Publication: | 2008 |
| Alkuperäinen tekijä: | Zweifel, Zeugin |
| Journal: | New Phytologist |
| Volume: | 179 |
| Numero: | 4 |
| Pagination: | 1070 - 1079 |
| Date Published: | Jan-09-2008 |
| ISSN: | 0028646X |
| Avainsanat: | cavitation, drought stress, embolism, tree water deficit, ultrasonicacoustic emission |
| Abstract: | -
Ultrasonic acoustic emission (UAE) in trees is often related to collapsing water columns in the flow path as a result of tensions that are too strong (cavitation). However, in a decibel (dB) range below that associated with cavitation, a close relationship was found between UAE intensities and stem radius changes.
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UAE was continuously recorded on the stems of mature field‐grown trees of Scots pine (Pinus sylvestris) and pubescent oak (Quercus pubescens) at a dry inner‐Alpine site in Switzerland over two seasons. The averaged 20‐Hz records were related to microclimatic conditions in air and soil, sap‐flow rates and stem‐radius fluctuations de‐trended for growth (ΔW).
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Within a low‐dB range (27 ± 1 dB), UAE regularly increased and decreased in a diurnal rhythm in parallel with ΔW on cloudy days and at night. These low‐dB emissions were interrupted by UAE abruptly switching between the low‐dB range and a high‐dB range (36 ± 1 dB) on clear, sunny days, corresponding to the widely supported interpretation of UAE as sound from cavitations.
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It is hypothesized that the low‐dB signals in drought‐stressed trees are caused by respiration and/or cambial growth as these physiological activities are tissue water‐content dependent and have been shown to produce courses of CO2 efflux similar to our courses of ΔW and low‐dB UAE.
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| URL: | http://blackwell-synergy.com/doi/abs/10.1111/nph.2008.179.issue-4 |
| DOI: | 10.1111/nph.2008.179.issue-410.1111/j.1469-8137.2008.02521.x |
