Reduction in branch sapwood hydraulic permeability as a factor limiting survival of lower branches of lodgepole pine

Protz, Clark G.; Silins, U.; Lieffers, Victor J.

doi:10.1139/cjfr-30-7-1088

Cited by 33 publications

(60 citation statements)

References 29 publications

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“…Clearwater and Meinzer (2001) found that both specific and leaf-specific hydraulic conductivities (LSC) in Eucalyptus grandis Hill ex Maiden increased with branch height in the crown, while LSC declined as the branch grew larger. Protz et al (2000) reported that hydraulic permeability in Pinus contorta Dougl. ex Loud., expressed on either leaf area or sapwood area basis, was significantly smaller in lower branches (0.16·10 À5 and 5.82·10 À5 m 2 , respectively) than upper branches (0.26·10 À5 and 10.47·10 À5 m 2 , respectively).…”

Section: Discussionmentioning

confidence: 99%

“…Therefore, within a crown, the length of the water transport pathway does not necessarily determine the resistance to the flow of water, because both the specific conductivity of xylem and the leaf area to sapwood area ratio may vary among different parts of the crown. However, there are still few studies indicating a systematic variation in xylem hydraulic capacity between the branches inserted at different heights in the stem (Joyce and Steiner 1995;Protz et al 2000;Lemoine et al 2002;Aasamaa et al 2004).…”

Section: Introductionmentioning

confidence: 99%

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Effects of light availability versus hydraulic constraints on stomatal responses within a crown of silver birch

Sellin

Kupper

2004

Oecologia

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Responses of leaf conductance (gL) to variation in photosynthetic photon flux density (QP), leaf-to-air vapour pressure difference (VPD), bulk leaf water potential (Psi(x)), and total hydraulic conductance (GT) were examined in silver birch (Betula pendula Roth) with respect to leaf position in the crown. To reduce limitations caused by insufficient water supply or low light availability, experiments were also performed with branchlets cut from two different canopy layers. The intact upper-canopy leaves demonstrated 1.8-2.0 times higher (P<0.001) daily maxima of gL compared with the lower-canopy leaves growing in the shadow of upper branches. In the morning, gL in the shade foliage was primarily constrained by low light availability, in the afternoon, by limited water supply. Leaf conductance decreased when Psi(x) fell below certain values around midday, while the sun foliage experienced greater negative water potentials than the shade foliage. Midday stomatal openness was controlled by leaf water status and temperature, rather than by transpiration rate (E) via the feedforward mechanism. Mean GT was 1.7 times higher (P<0.001) for the upper-canopy foliage compared to that of the lower canopy. At least 34-39% of the total resistance to the water flow from soil up to the shade foliage, and 54% up to the sun foliage, resided in 30-cm distal parts of the branches. Artificial reduction of hydraulic constraints raised Psi(x) and made gL less sensitive to changes in both atmospheric and plant factors. Improved water supply increased gL and E in the lower-canopy foliage, but not in the upper-canopy foliage. The results support the idea that leaves in the lower canopy are hydraulically more constrained than in the upper canopy.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effects of light availability versus hydraulic constraints on stomatal responses within a crown of silver birch

Sellin

Kupper

2004

Oecologia

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“…Their complicated branching patterns mean that each leaf on the tree will have a different path length from the ground. Also, the hydraulic architecture has been shown to be designed in such a way that branches receiving more sunlight are hydraulically favored over lower branches (Protz et al 2000). Much of this complexity could be avoided if a simpler tree species such as palms were used to study hydraulic limitation.…”

Section: Introductionmentioning

confidence: 99%

Comparative hydraulic and anatomic properties in palm trees (Washingtonia robusta) of varying heights: implications for hydraulic limitation to increased height growth

Renninger

Phillips

Hodel

2009

Trees

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As trees grow taller, the energetic cost of moving water to the leaves becomes higher and could begin to limit carbon gain and subsequent growth. The hydraulic limitation hypothesis states that as trees grow taller, the path length and therefore frictional resistance of water flow increases, leading to stomatal closure, reduced photosynthesis and decreased height growth in tall trees. Although this hypothesis is supported by the physical laws governing water movement in trees, its validation has been complicated by the complex structure of most tree species. Therefore, this study tested the hydraulic limitation hypothesis in Washingtonia robusta (H. Wendl.), a palm that, while growing to tall heights, is still structurally simple enough to act as a model organism for testing. There were no discernable relationships between tree height and stomatal conductance, stomatal densities, guard cell lengths, leaf dry mass per unit area (LMA) or sap flux, suggesting that these key aspects of hydraulic limitation are not reduced in taller palms. Taller palms did, however, have higher maximum daily photosynthetic assimilation rates, lower minimum leaf water potentials that occurred earlier in the day and fewer, smaller leaves than did shorter palms. Leaf epidermal cells were also smaller in taller palms compared with shorter ones. These findings are consistent with hydraulic compensation in that tall palms may be overcoming the increased path length resistance through smaller, more efficient leaves and lower leaf water potentials than shorter palms.

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“…Opposite patterns of hydraulic capacity have often been revealed within crowns of both coniferous and broad-leaved trees: specific hydraulic conductivity of branches (Protz et al 2000;Lemoine et al 2002;Jerez et al 2004;Burgess et al 2006) or shoot hydraulic conductance increased with branch height in the crown (Aasamaa et al 2004). Also apparent soil-to-leaf hydraulic conductance (G T ), defined as a current transpiration rate divided by water potential drop from soil to leaves (Meinzer et al 1995;Wullschleger et al 1998), has been shown to increase from basal to top branches (Sellin and Kupper 2004, 2005a, 2007a.…”

Section: Introductionmentioning

confidence: 99%

“…Distribution of hydraulic conductance within the crown is an essential factor driving canopy development during forest maturation. Protz et al (2000) suggested that reduction in branch sapwood hydraulic conductivity over time limits survival of lower branches, and therefore controls the vertical crown recession in closed-canopy trees. On the other hand, forest management operations may have substantial consequences on plant hydraulics, affecting both growth rate of trees and wood characteristics (Renninger et al 2006).…”

Section: Introductionmentioning

confidence: 99%

Distribution of vessel size, vessel density and xylem conducting efficiency within a crown of silver birch (Betula pendula)

Sellin

Rohejärv

Rahi

2007

Trees

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Spatial patterns in vessel diameter, vessel density and xylem conducting efficiency within a crown were examined in closed-canopy trees of silver birch (Betula pendula). The variation in anatomical and hydraulic characteristics of branches was considered from three perspectives: vertically within a crown (lower, middle and upper crown), radially along main branches (proximal, middle and distal part), and with respect to branch orders (first-, second-and third-order branches). Hydraulically weighted mean diameter of vessels (D h ) and theoretical specific conductivity of the xylem (k t ) exhibited no vertical trend within the tree crown, whereas leaf-specific conductivity of the xylem (LSC t ) decreased acropetally. Variation in LSC t was governed by sapwood area to leaf area ratio (Huber value) rather than by changes in xylem anatomy. The acropetal increase in soil-to-leaf conductance (G T ) within the birch canopy is attributable to longer path length within the lower-crown branches and higher hydraulic resistance of the shade leaves. D h , k t and LSC t decreased, while vessel density (VD) and relative area of vessel lumina (VA) increased distally along main branches. A strong negative relationship between vessel diameter and VD implies a trade-off between hydraulic efficiency and mechanical stability of xylem. D h and VD combined explained 85.4% of the total variation of k t in the regression model applied to the whole data set. Xylem in fast-growing branches (primary branches) had greater area of vessel lumina per unit crosssectional area of sapwood, resulting in a positive relationship between branch radial growth rate and k t . D h , k t and LSC t decreased, whereas VD increased with increasing branch order. This pattern promotes the hydraulic dominance of primary branches over the secondary branches and their dominance over tertiary branches. In this way crown architecture contributes to preferential water flow along the main axes, potentially providing better water supply for the branch apical bud and foliage located in the outer, betterinsolated part of the crown.

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Reduction in branch sapwood hydraulic permeability as a factor limiting survival of lower branches of lodgepole pine

Cited by 33 publications

References 29 publications

Effects of light availability versus hydraulic constraints on stomatal responses within a crown of silver birch

Effects of light availability versus hydraulic constraints on stomatal responses within a crown of silver birch

Comparative hydraulic and anatomic properties in palm trees (Washingtonia robusta) of varying heights: implications for hydraulic limitation to increased height growth

Distribution of vessel size, vessel density and xylem conducting efficiency within a crown of silver birch (Betula pendula)

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