Field measurements of ultrasonic acoustic emissions and stem diameter variations.: New insight into the relationship between xylem tensions and embolism
Field measurements of ultrasonic acoustic emissions and stem diameter variations.: New insight into the relationship between xylem tensions and embolism
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DOI：
10.1093/treephys/25.2.237
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发表时间：
2005-02-01
期刊：
影响因子：
4
通讯作者：
Mencuccini, M
中科院分区：
文献类型：
--
作者：
Hölttä, T;Vesala, T;Mencuccini, M
我们通过同时监测超声波发射和茎木质部直径的变化，研究了田间条件下相互关联的木质部水分张力和栓塞动力学。用线性位移传感器测量茎木质部直径的变化，以估计汁液张力的变化。测量的超声声发射与木质部直径的变化很好地吻合，表明栓塞处的各个峰与水张力的峰同时出现。测量之间良好的时间分辨率使该方法特别适合于在短时间尺度上观察血栓动力学。也可以进行更长时间的测量来监测水紧张和血栓的每日模式，因为这些技术是非破坏性的。超声声发射主要发生在茎木质部直径减小的时期，即当水张力足够高时，水张力增加。当木质部直径增大，即水张力降低时，也会发生栓塞，但在这种情况下，栓塞管的数量很少。
We examined interrelated xylem water tensions and embolism dynamics under field conditions by simultaneously monitoring ultra-acoustic emissions and changes in stem xylem diameter. Variation in stem xylem diameter was measured with linear displacement transducers to estimate variation in sap tension. Measured ultrasonic acoustic emissions coincided well with changes in xylem diameter, indicating that individual peaks in embolism occurred simultaneously with peaks in water tension. The good time resolution between measurements makes this method especially suitable for observing embolism dynamics on a short timescale. Longer lasting measurements can also be made to monitor inter-daily patterns in water tension and embolism because the techniques are non-destructive. Ultra-acoustic emissions occurred mainly during periods of decreasing stem xylem diameter, i.e., increasing water tension, when the water tension was high enough. Embolism also occurred during periods of increasing xylem diameter, i.e., decreasing water tension, but the number of embolizing conduits under these conditions was small.