A method for measuring hydraulic conductivity and embolism in xylem

Sperry, John S.; Donnelly, J. R.; Tyree, Melvin T.

doi:10.1111/j.1365-3040.1988.tb01774.x

Cited by 943 publications

(801 citation statements)

References 19 publications

(17 reference statements)

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“…We used field measurements of branch hydraulic conductivity during ongoing mortality and simulations with a detailed plant hydraulics model to interpret and gain insight into lethal levels in CWD calculated over 2000-2013 during which a pixel of forest was likely to have experienced mortality. Branch segments (n = 104) were acquired from 33 aspen stands across a broad array of topography and hydraulic conductivity was measured via a standard protocol 29 . A detailed plant hydraulics model 21 was parameterized using published vulnerability-to-cavitation curves and extensive branch and whole-tree hydraulic data from aspen trees of the study region and then evaluated against published estimates of transpiration and whole-tree hydraulic conductance in three aspen stands.…”

Section: Methodsmentioning

confidence: 99%

Tree mortality predicted from drought-induced vascular damage

et al. 2015

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The projected responses of forest ecosystems to warming and drying associated with twenty-first-century climate change vary widely from resiliency to widespread tree mortality 1-3 . Current vegetation models lack the ability to account for mortality of overstorey trees during extreme drought owing to uncertainties in mechanisms and thresholds causing mortality 4,5 . Here we assess the causes of tree mortality, using field measurements of branch hydraulic conductivity during ongoing mortality in Populus tremuloides in the southwestern United States and a detailed plant hydraulics model. We identify a lethal plant water stress threshold that corresponds with a loss of vascular transport capacity from air entry into the xylem. We then use this hydraulic-based threshold to simulate forest dieback during historical drought, and compare predictions against three independent mortality data sets. The hydraulic threshold predicted with 75% accuracy regional patterns of tree mortality as found in field plots and mortality maps derived from Landsat imagery. In a high-emissions scenario, climate models project that drought stress will exceed the observed mortality threshold in the southwestern United States by the 2050s. Our approach provides a powerful and tractable way of incorporating tree mortality into vegetation models to resolve uncertainty over the fate of forest ecosystems in a changing climate.Forests play a central role in global water, energy and biogeochemical cycles and provide substantial ecosystem services to societies around the globe 6 . Yet the fate of forest ecosystems in a changing climate is highly uncertain. Rising atmospheric CO 2 concentrations may benefit trees, particularly through increasing water-use efficiency 7 , but concomitant increases in temperature and drought stress could potentially overwhelm these benefits, leading to widespread forest dieback in many ecosystems globally 8 . Although precipitation projections under climate scenarios are more variable and uncertain, general circulation models project consistent increases in air temperature and thus evaporation over much of the world and resulting decreases in soil moisture in many regions, leading to more intense and frequent droughts 9 . Recent studies have indicated resilience in forest biomes in response to early twenty-first-century droughts through inter-annual modulations in water-use efficiency 10 and long-term increases in forest water-use efficiency 7 . In contrast, severe regional droughts have strongly decreased the carbon sink of key forest ecosystems [11][12][13] and widespread, climate-induced tree mortality has been observed around the globe 8,14 .

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Section: Methodsmentioning

confidence: 99%

Tree mortality predicted from drought-induced vascular damage

et al. 2015

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“…Repeated conductivity measurements after Sperry et al (1988) conducted in 48-72 roots per species in summer 2008 indicated that Fagus, Fraxinus, Acer, and Carpinus roots experienced conductivity losses (PLC) in the range of 16.2-17.8% in this period which were attributed to xylem embolism; the PLC mean of Tilia roots was significantly smaller (9.3%, Table 2). In Fagus and Fraxinus roots, the conductivity loss increased with a seasonal decrease in soil matrix potential while no dependence of PLC on Ψ S was detected for the other three species (Fig.…”

Section: ±22 Amentioning

confidence: 99%

“…Prior to measurement, each segment was re-cut under water with a razor blade; the length of the root segments used for measurement was at least 6 cm. Measurements of hydraulic conductivity (k h ) were consecutively conducted at least three times in each root segment according to the specifications made by Sperry et al (1988). We used de-ionized water containing sodium-silver chloride for the flow measurement.…”

Section: Native Root Hydraulic Conductivity and Embolismmentioning

confidence: 99%

“…Initial and maximum axial hydraulic conductivity of segments of small-diameter roots (2-6 mm in diameter) were determined empirically following the protocol given by Sperry et al (1988). Twelve root segments per tree (48-72 per species) were collected on different occasions between July and September 2008 in the topsoil (0-10 cm depth).…”

Section: Native Root Hydraulic Conductivity and Embolismmentioning

confidence: 99%

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Hydraulic properties and embolism in small-diameter roots of five temperate broad-leaved tree species with contrasting drought tolerance

Köcher

Horna

Beckmeyer

et al. 2012

Annals of Forest Science

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Abstract& Context It has been estimated that about half of a plant's total hydraulic resistance is located belowground, but it is not well known how temperate tree species differ in root hydraulic properties and how these traits vary with the species' drought tolerance. & Aims We examined root anatomical and hydraulic traits in five broad-leaved tree species with different drought tolerance, analyzed the relation between root anatomy and hydraulic conductivity and root embolism, and investigated the relation of these traits to the species' drought tolerance. & Methods In small-diameter roots (2-6 mm), we measured vessel diameters and vessel density, specific hydraulic conductivity, and the percental loss of conductivity ("native" embolism) during summer in a mixed forest. & Results Specific conductivity was positively related to vessel diameter but not to vessel density. Drought-tolerant Fraxinus showed the smallest mean vessel diameters and drought-sensitive Fagus the largest. Specific conductivity was highly variable among different similar-sized roots of the same species with a few roots apparently functioning as "high-conductivity roots". & Conclusion The results show that coexisting tree species can differ largely in root hydraulic traits with more droughtsensitive trees apparently having larger mean vessel diameters in their roots than tolerant species. However, this difference was not related to the observed root conductivity losses due to embolism.

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“…Twigs were collected on day 15 of each month. Measurements were taken using the hydraulic equipment first described by Sperry et al (1988) and modified by Lo Gullo & Salleo (1991). Briefly, twigs were cut off while immersed in water, before dawn (i.e.…”

Section: Hydraulic Measurements Of Xylem Embolismmentioning

confidence: 99%

Drought resistance of Quercus pubescens as a function of root hydraulic conductance, xylem embolism and hydraulic architecture

Nardini

Pitt

1999

New Phytologist

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Water relations, xylem embolism, root and shoot hydraulic conductance of both young plants in the field and potted seedlings of Quercus pubescens have been studied with the aim of investigating whether these variables may account for the well known adaptation of this oak species to arid habitats. Our data revealed that Q. pubescens is able to maintain high leaf relative water contents under water stress conditions. In fact, relative water contents measured in summer (July) did not differ from those recorded in April. This was apparently achieved by compensating water loss by an equal amount of water uptake. Such a drought avoidance strategy was made possible by the recorded high hydraulic efficiency of stems and roots under water stress. In fact, root hydraulic conductance of field-grown plants was maintained high in summer when the percentage loss of hydraulic conductance of stems was lowest. The hydraulic architecture of young plants of Q. pubescens measured in terms of partitioning of hydraulic resistances along the water pathway revealed that the highest hydraulic resistance was located in stems of the current year's growth. This hydraulic architecture is interpreted as consistent with the adaptation of Q. pubescens to arid habitats as a consequence of the recorded seasonal changes in water relation parameters as well as in root and stem hydraulics.

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A method for measuring hydraulic conductivity and embolism in xylem

Cited by 943 publications

References 19 publications

Tree mortality predicted from drought-induced vascular damage

Tree mortality predicted from drought-induced vascular damage

Hydraulic properties and embolism in small-diameter roots of five temperate broad-leaved tree species with contrasting drought tolerance

Drought resistance of Quercus pubescens as a function of root hydraulic conductance, xylem embolism and hydraulic architecture

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