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Maximum heat ratio: bi-directional method for fast and slow sap flow measurements

Gutierrez Lopez, Jose and Pypker, Thomas and Licata, Julian and Burgess, Stephen S. O. and Asbjornsen, Heidi (2021). Maximum heat ratio: bi-directional method for fast and slow sap flow measurements. Plant and Soil. 469 , 503-523
[Research article]

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Abstract

Background As sap flow research expands, new challenges such as fast sap flows or flows co-occurring with freeze/thaw cycles appear, which are not easily addressed with existing methods. In order to address these new challenges, sap flow methods capable of measuring bidirectional, high and slow sap flux densities (F-d, cm(3) cm(-2) h(-1)), thermal properties and stem water content with minimum sensitivity to stem temperature are required. Purpose In this study we assessed the performance of a new low-power ratio-based algorithm, the maximum heat ratio (MHR) method, and compare it with the widely known heat ratio (HR) method using a cut-tree study to test it under high flows using Eucalyptus grandis trees, and a freeze/thaw experiment using Acer saccharum trunks to test its response to fast changing stem temperatures that result in freeze/thaw cycles. Results Our results indicate that MHR and HR had a strong (R-2 = 0.90) linear relationship within a F-d range of 0-45 cm(3) cm(-2) h(-1). Using the MHR algorithm, we were able to estimate wood thermal properties and water content, while extending the measuring range of HR to approximately 0-130 (cm(3) cm(-2) h(-1)). In our freeze/thaw experiment, the main discrepancy between MHR and HR was observed during freezing, where HR had consistently lower F-d (up to 10 cm(3) cm(-2) h(-1)), with respect to MHR. However, both algorithms identified similar zero flows. Conclusion Consequently, MHR can be an easy-to-implement alternative algorithm/method capable of handling extreme climatic conditions, which can also run simultaneously with HR.

Authors/Creators:Gutierrez Lopez, Jose and Pypker, Thomas and Licata, Julian and Burgess, Stephen S. O. and Asbjornsen, Heidi
Title:Maximum heat ratio: bi-directional method for fast and slow sap flow measurements
Series Name/Journal:Plant and Soil
Year of publishing :2021
Volume:469
Page range:503-523
Number of Pages:21
Publisher:SPRINGER
ISSN:0032-079X
Language:English
Publication Type:Research article
Article category:Scientific peer reviewed
Version:Published version
Copyright:Creative Commons: Attribution 4.0
Full Text Status:Public
Subjects:(A) Swedish standard research categories 2011 > 4 Agricultural Sciences > 401 Agricultural, Forestry and Fisheries > Soil Science
Keywords:Maximum heat ratio, Thermal diffusivity, Volumetric water content, Freeze, thaw cycles, Volumetric heat capacity
URN:NBN:urn:nbn:se:slu:epsilon-p-113814
Permanent URL:
http://urn.kb.se/resolve?urn=urn:nbn:se:slu:epsilon-p-113814
Additional ID:
Type of IDID
DOI10.1007/s11104-021-05066-w
Web of Science (WoS)000698058700002
ID Code:26658
Faculty:S - Faculty of Forest Sciences
Department:(S) > Dept. of Forest Ecology and Management
Deposited By: SLUpub Connector
Deposited On:05 Jan 2022 11:25
Metadata Last Modified:05 Jan 2022 11:31

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