Abstract
In the short term, trees rely on the internal storage of water because it affects their ability to sustain photosynthesis and growth. However, water is not rapidly available for transpiration from all the compartments of the plant and the living tissues of the stem act as a buffer to preclude low water potentials during peaks of transpiration. In this paper, electronic dendrometers were used from mid-June to mid-September 2008 to compare the radius variations in stem and roots of black spruce [Picea mariana (Mill.) B.S.P.] in two sites of the boreal forest of Quebec, Canada, with different soil characteristics and water retention. The duration of the daily cycles was similar between sites and measurement heights but greater amplitudes of contraction and expansion were observed on the stem and in the site with the shallowest soil organic layer. The expansion phase had higher amplitudes and lasted longer than contraction. On average, the contraction phase occurred between 07:00 and 16:30 (legal time), while expansion lasted 14.5 h. The roots in the site with the deepest organic layer showed a wider variation in the onset of contraction, which could be as late as 13:00. The probability of observing the contraction phase depended on precipitation. With a precipitation <0.5 mm h−1, the bivariate posterior probabilities estimated >60% probability of observing contraction between 05:00 and 21:00, decreasing to 20% with precipitation >1.1 mm h−1. These findings demonstrated that the depth of the organic layer plays an important role in maintaining the internal water reserve of trees. The dynamics of water depletion and replenishment can modify the water potential of xylem and cell turgor during the enlargement phase, thus affecting radial growth. Changes in temperature and precipitation regime could influence the dynamics of internal water storage in trees growing on shallower and drier soils.
Highlights
In the short term, trees rely on internal storage to constantly fulfill their water needs because there may be a significant delay between water loss from leaves and water uptake by roots (Cermak et al, 2007)
With a precipitation 60% probability of observing contraction between 05:00 and 21:00, decreasing to 20% with precipitation >1.1 mm h−1. These findings demonstrated that the depth of the organic layer plays an important role in maintaining the internal water reserve of trees
In the boreal forest, precipitation is an important factor in the replenishment of the internal water reserves in trees growing on the shallowest and driest organic layers
Summary
Trees rely on internal storage to constantly fulfill their water needs because there may be a significant delay between water loss from leaves and water uptake by roots (Cermak et al, 2007). Trees can store water in three different compartments: (i) in sapwood, (ii) in the cell walls or inactive vessels, and (iii) within the living cells of leaves, bark, and wood rays (Zimmermann, 1983). The water stored in the living cells of bark can more efficiently contribute to the daily transpiration stream because of the elasticity of the tissue and their high connectivity with xylem (Herzog et al, 1995; Steppe et al, 2005). There is evidence that the living cells of the bark parenchyma, phloem, and cambium are among the most important compartments for water storage in trees (Lassoie, 1973; Waring et al, 1979; Steppe et al, 2005)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
