Journal Article

Variability with xylem depth in sap flow in trunks and branches of mature olive trees

Nadezhda Nadezhdina, Valeriy Nadezhdin, Maria Isabel Ferreira and Andrea Pitacco

in Tree Physiology

Volume 27, issue 1, pages 105-113
Published in print January 2007 | ISSN: 0829-318X
Published online January 2007 | e-ISSN: 1758-4469 | DOI: http://dx.doi.org/10.1093/treephys/27.1.105
Variability with xylem depth in sap flow in trunks and branches of mature olive trees

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Knowledge of sap flow variability in tree trunks is important for up-scaling transpiration from the measuring point to the whole-tree and stand levels. Natural variability in sap flow, both radial and circumferential, was studied in the trunks and branches of mature olive trees (Olea europea L., cv Coratina) by the heat field deformation method using multi-point sensors. Sapwood depth ranged from 22 to 55 mm with greater variability in trunks than in branches. Two asymmetric types of sap flow radial patterns were observed: Type 1, rising to a maximum near the mid-point of the sapwood; and Type 2, falling continuously from a maximum just below cambium to zero at the inner boundary of the sapwood. The Type 1 pattern was recorded more often in branches and smaller trees. Both types of sap flow radial patterns were observed in trunks of the sample trees. Sap flow radial patterns were rather stable during the day, but varied with soil water changes. A decrease in sap flow in the outermost xylem was related to water depletion in the topsoil. We hypothesized that the variations in sap flow radial pattern in a tree trunk reflects a vertical distribution of water uptake that varies with water availability in different soil layers.

Keywords: automatic irrigation control; heat field deformation method; multi-point sensors; Quercus suber; sap flow radial pattern; vertical profile of root absorption; water stress indicator

Journal Article.  0 words. 

Subjects: Plant Sciences and Forestry

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