Document Detail

Variation in the radial patterns of sap flux density in pubescent oak (Quercus pubescens) and its implications for tree and stand transpiration measurements.
MedLine Citation:
PMID:  17241996     Owner:  NLM     Status:  MEDLINE    
Radial variation in sap flux density across the sapwood was assessed by the heat field deformation method in several trees of Quercus pubescens Wild., a ring-porous species. Sapwood depths were delimited by identifying the point of zero flow in radial patterns of sap flow, yielding tree sapwood areas that were 1.5-2 times larger than assumed based on visual examinations of wood cores. The patterns of sap flow varied both among trees and diurnally. Rates of sap flow were higher close to the cambium, although there was a significant contribution from the inner sapwood, which was greater (up to 60% of total flow) during the early morning and late in the day. Accordingly, the normalized difference between outer and inner sapwood flow was stable during the middle of the day, but showed a general decline in the afternoon. The distribution of sap flux density across the sapwood allowed us to derive correction coefficients for single-point heat dissipation sap flow measurements. We used daytime-averaged coefficients that depended on the particular shape of the radial profile and ranged between 0.45 and 1.28. Stand transpiration calculated using the new method of estimating sapwood areas and the radial correction coefficients was similar to (Year 2003), or about 25% higher than (Year 2004), previous uncorrected values, and was 20-30% of reference evapotranspiration. We demonstrated how inaccuracies in determining sapwood depths and mean sap flux density across the sapwood of ring-porous species could affect tree and stand transpiration estimates.
Rafael Poyatos; Jan Cermák; Pilar Llorens
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Tree physiology     Volume:  27     ISSN:  0829-318X     ISO Abbreviation:  Tree Physiol.     Publication Date:  2007 Apr 
Date Detail:
Created Date:  2007-01-23     Completed Date:  2007-05-31     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  100955338     Medline TA:  Tree Physiol     Country:  Canada    
Other Details:
Languages:  eng     Pagination:  537-48     Citation Subset:  IM    
Institute of Earth Sciences Jaume Almera (CSIC), Lluís Solé Sabarís s/n, 08208 Barcelona, Spain.
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MeSH Terms
Circadian Rhythm
Plant Transpiration / physiology*
Quercus / physiology*

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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