Articles
DECOUPLING STRUCTURAL AND ENVIRONMENTAL DETERMINANTS OF SAP VELOCITY USING HEAT PULSE METHODS
Article number
846_5
Pages
69 – 76
Language
English
Abstract
Our work presents a novel theoretical framework for the study of individual tree sap flow that incorporates both spatial and temporal variability in sap velocities.
The instantaneous sap velocity at any point in the radial profile of xylem tissue is defined as the product of two components: (1) a time-invariant sap velocity distribution linked to the species-specific anatomical and structural properties of the conducting xylem, and (2) a time-varying term linked to the dynamics of the atmospheric water demand and available soil moisture.
The separation of structural and temporal variation in sap velocity observations provides a direct mechanism for investigating how sap flow is governed by variation in environmental conditions as well as a means for comparing characteristic rates of plant water use among individuals of varying size.
Experimental evidence supports our theoretical framework in the case of a population of sugar maples in a mixed deciduous forest, where observations were taken using the compensation heat pulse technique from a wide range of tree sizes, under varying soil water availability and atmospheric transpiration demand.
While these results require further confirmation in order to be generalized, they nevertheless offer the basis to improve our understanding of the dependence of sap flow velocity from variability in bio-geophysical determinants of tree transpiration.
The instantaneous sap velocity at any point in the radial profile of xylem tissue is defined as the product of two components: (1) a time-invariant sap velocity distribution linked to the species-specific anatomical and structural properties of the conducting xylem, and (2) a time-varying term linked to the dynamics of the atmospheric water demand and available soil moisture.
The separation of structural and temporal variation in sap velocity observations provides a direct mechanism for investigating how sap flow is governed by variation in environmental conditions as well as a means for comparing characteristic rates of plant water use among individuals of varying size.
Experimental evidence supports our theoretical framework in the case of a population of sugar maples in a mixed deciduous forest, where observations were taken using the compensation heat pulse technique from a wide range of tree sizes, under varying soil water availability and atmospheric transpiration demand.
While these results require further confirmation in order to be generalized, they nevertheless offer the basis to improve our understanding of the dependence of sap flow velocity from variability in bio-geophysical determinants of tree transpiration.
Publication
Authors
D. Dragoni, K.K. Caylor
Keywords
sap flow, sugar maple, Acer saccarum, sap velocity profile, transpiration
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