Time constant for water transport in loblolly pine trees estimated from time series of evaporative demand and stem sapflow

Phillips, Nathan; Nagchaudhuri, Abhijit; Oren, Ram; Katul, Gabriel G.

doi:10.1007/s004680050102

Cited by 172 publications

(128 citation statements)

References 17 publications

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“…The two thermocouples were installed at the midpoint of 1.5 mm-diameter stainless steel needles, and inserted into aluminum tubes as described by Phillips et al [31]. Each probe was 2.5 mm in diameter and 250 mm long.…”

Section: Sap Flow Sensor Construction and Installationmentioning

confidence: 99%

Sapwood hydraulic recovery following thinning in lodgepole pine

2006

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-Sapflow in lodgepole pine (Pinus contorta) was measured over the summer of 2002 to assess the impact of reduced sapwood permeability (k) after thinning on tree water use. Lodgepole pine in recently thinned (RT), thinned five years prior (5T), and un-thinned (C) stands were instrumented with thermal dissipation sap flow sensors. Daily water use varied considerably (10.8-0.04 L Day −1 ), but trees in the thinned areas used more water. Despite lower k and leaf specific hydraulic capacity (Q L ) in both RT and 5T trees, leaf related sapflow rates (Q l ) were generally higher than for C trees. RT trees appeared to experience water stress immediately following thinning in June, but by mid August maintained higher Q l and canopy stomatal conductance than both 5T and C trees. Allocation to radial growth following thinning appears to maintain sufficient sapwood area, and may offset damage to conducting tissues enabling lodgepole pine trees to tolerate periodic water stress.

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Section: Sap Flow Sensor Construction and Installationmentioning

confidence: 99%

Sapwood hydraulic recovery following thinning in lodgepole pine

2006

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“…6). If sap flow in the branches of the upper crown is assumed to be a surrogate for transpiration, then lags between changes in sap flow in the crown and at the base of the tree reflect exchange of water between the transpiration stream and storage compartments located between the points at which sap flow is measured (Phillips et al 1997;Goldstein et al 1998). The maximum difference between crown and basal sap flow when transpiration is initially increasing during the morning hours can thus be used as an index of relative diurnal water storage capacity.…”

Section: Spatial Variation In Sap Flowmentioning

confidence: 99%

“…Capacitive exchange of water between storage compartments and the transpiration stream will introduce a lag between variations in transpiration and variations in sap flow and will increasingly dampen variations in the driving force for water movement as the base of the tree is approached. The magnitude of this lag, and therefore the duration of non-steady state flow, generally increases with tree size and with increasing distance from the crown (Phillips et al 1997;Goldstein et al 1998). Thus, even if xylem hydraulic properties were identical near the ground and at the base of the crown in a large tree, it is likely that corresponding patterns of sap flow would differ.…”

Section: Introductionmentioning

confidence: 99%

Axial and radial water transport and internal water storage in tropical forest canopy trees

Meinzer²,

et al. 2003

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Heat and stable isotope tracers were used to study axial and radial water transport in relation to sapwood anatomical characteristics and internal water storage in four canopy tree species of a seasonally dry tropical forest in Panama. Anatomical characteristics of the wood and radial profiles of sap flow were measured at the base, upper trunk, and crown of a single individual of Anacardium excelsum, Ficus insipida, Schefflera morototoni, and Cordia alliodora during two consecutive dry seasons. Vessel lumen diameter and vessel density did not exhibit a consistent trend axially from the base of the stem to the base of the crown. However, lumen diameter decreased sharply from the base of the crown to the terminal branches. The ratio of vessel lumen area to sapwood cross-sectional area was consistently higher at the base of the crown than at the base of the trunk in A. excelsum, F. insipida and C. alliodora, but no axial trend was apparent in S. morototoni. Radial profiles of the preceding wood anatomical characteristics varied according to species and the height at which the wood samples were obtained. Radial profiles of sap flux density measured with thermal dissipation sensors of variable length near the base of the crown were highly correlated with radial profiles of specific hydraulic conductivity (k s ) calculated from xylem anatomical characteristics. The relationship between sap flux density and k s was speciesindependent. Deuterium oxide (D 2 O) injected into the base of the trunk of the four study trees was detected in the water transpired from the upper crown after only 1 day in the 26-m-tall C. alliodora tree, 2 days in the 28-m-tall F. insipida tree, 3 days in the 38-m-tall A. excelsum tree, and 5 days in the 22-m-tall S. morototoni tree. Radial transport of injected D 2 O was detected in A. excelsum, F. insipida and S. morototoni, but not C. alliodora. The rate of axial D 2 O transport, a surrogate for maximum sap velocity, was positively correlated with the predicted sapwood k s and with tree height normalized by the relative diurnal water storage capacity. Residence times for the disappearance of the D 2 O tracer in transpired water ranged from 2 days in C. alliodora to 22 days in A. excelsum and were positively correlated with a normalized index of diurnal water storage capacity. Capacitive exchange of water between stem storage compartments and the transpiration stream thus had a profound influence on apparent rates of axial water transport, the magnitude of radial water movement, and the retention time in the tree of water taken up by the roots. The inverse relationship between internal water exchange capacity and k s was consistent with a trade-off contributing to stability of leaf water status through highly efficient water transport at one extreme and release of stored water at the other extreme.

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“…As emphasized by Bonan [34], using the SURFER package [35] [21 ] and that we applied for these tree species (see discussion in Cabibel and Do [8] and Goulden and Field [20] [48,70].…”

mentioning

confidence: 99%

Retrieving leaf conductances from sap flows in a mixed Mediterranean woodland: a scaling exercise

Filho¹,

Damesin²,

Rambal³

et al. 1998

Ann. For. Sci.

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Abstract-Xylem sap-flux densities were monitored continuously using Granier-type sensors on five Quercus ilex, four Arbutus unedo and one Quercus pubescens from June 1993 to October 1994. Half-hourly measurements of incoming solar radiation, air temperature and humidity, horizontal wind speed and precipitation were carried out at the top of a tower at a height of 12 m, about 2 m above the canopy. Leaf physiological measurements (stomatal conductance, water potential) on individual sunlit leaves from each of the three tree species were obtained on seven complete or partial diurnal time courses. For these three species, to estimate leaf stomatal conductance, we used the big-leaf approach of Penman-Monteith. We have divided the leaves into sunlit and shaded. The model sums the individual-leaf model for only the sunlit fraction to produce the whole-canopy predictions. Transpiration was deduced from sap flux through a transfer function taking into account stem water storage. Stomatal conductance for a given species was evaluated half-hourly from transpiration and microclimate data inverting the Penman-Monteith equation. An empirical model was identified that related stomatal aperture to simultaneous variations of microclimate and plant water potential for the 1993 period. The predicted leaf conductances were validated against porometer data and those of the 1994 period. The diurnal patterns of predicted and measured transpiration indicated that stomatal conductance was accurately predicted.

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Time constant for water transport in loblolly pine trees estimated from time series of evaporative demand and stem sapflow

Cited by 172 publications

References 17 publications

Sapwood hydraulic recovery following thinning in lodgepole pine

Sapwood hydraulic recovery following thinning in lodgepole pine

Axial and radial water transport and internal water storage in tropical forest canopy trees

Retrieving leaf conductances from sap flows in a mixed Mediterranean woodland: a scaling exercise

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