Isotopic studies of leaf water. Part 1: A physically based two-dimensional model for pine needles

Shu, Yong; Feng, Xiahong; Posmentier, Eric S.; Sonder, Leslie J.; Faiia, Anthony M.; Yakir, Dan

doi:10.1016/j.gca.2008.05.062

Cited by 18 publications

(17 citation statements)

References 49 publications

(103 reference statements)

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“…Despite the known issues with the approach, we have confidence in the general veracity of the method based on several lines of evidence. First, the isotopic enrichment along single leaves is consistent with values observed through cryogenic extraction and Isotope Ratio Mass Spectrometry (not shown) [ Farquhar and Gan , ; Shu et al , ], second, the slope of δ D versus δ 18 O in the stem waters falls along the slope derived from precipitation samples (i.e., the local meteoric water line) measured (Figure ), and third, the filter paper calibrations and blanks provided a sound reference.…”

Section: Methodsmentioning

confidence: 99%

The nocturnal water cycle in an open‐canopy forest

Berkelhammer

Bailey

et al. 2013

JGR Atmospheres

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[1] The movement of moisture into, out-of, and within forest ecosystems is modulated by feedbacks that stem from processes which couple plants, soil, and the atmosphere. While an understanding of these processes has been gleaned from Eddy Covariance techniques, the reliability of the method suffers at night because of weak turbulence. During the summer of 2011, continuous profiles of the isotopic composition (i.e., ı 18 O and ıD) of water vapor and periodic measurements of soil, leaf, and precipitation pools were measured in an open-canopy ponderosa pine forest in central Colorado to study within-canopy nocturnal water cycling. The isotopic composition of the nocturnal water vapor varies significantly based on the relative contributions of the three major hydrological processes acting on the forest: dewfall, exchange of moisture between leaf waters and canopy vapor, and periodic mixing between the canopy and background air. Dewfall proved to be surprisingly common ( 30% of the nights) and detectable on both the surface and within the canopy through the isotopic measurements. While surface dew could be observed using leaf wetness and soil moisture sensors, dew in the foliage was only measurable through isotopic analysis of the vapor and often occurred even when no dew accumulated on the surface. Nocturnal moisture cycling plays a critical role in water availability in forest ecosystems through foliar absorption and transpiration, and assessing these dynamics, as done here, is necessary for fully characterizing the hydrological controls on terrestrial productivity.

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Section: Methodsmentioning

confidence: 99%

The nocturnal water cycle in an open‐canopy forest

Berkelhammer

Bailey

et al. 2013

JGR Atmospheres

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“…Stem water flows into leaves where transpiration (evaporation from leaf stomata) enriches it in D and 18 O (e.g. Shu et al, 2008), with the magnitude intimately dependent upon leaf structure, transpiration rates and climate (Kahmen et al, 2008). Plant water signatures are transferred to plant-wax hydrogen with a negative offset due to biochemical fractionation (Sessions, 2006;Smith and Freeman, 2006;Hou et al, 2008).…”

Section: Competing Influences On Plant-wax Dd Valuesmentioning

confidence: 99%

“…Indeed, isotope models for soil evaporation and plant transpiration are derived from the same equations governing the hydrologic and isotopic balance of lake systems (e.g. Gonfiantini, 1986;Barnes and Allison, 1988;Shu et al, 2008). The enrichment of lake water relative to precipitation (e LW/ppt ) is a potentially useful measure of climatic effects on evaporative enrichment of waters in plants and soils and ultimately on plant-wax dD variations.…”

Section: Aridity Increases N-alkane Dd and E Amentioning

confidence: 99%

Effects of aridity and vegetation on plant-wax δD in modern lake sediments

Polissar¹,

Freeman²

2010

Geochimica et Cosmochimica Acta

169

116

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“…2a, c, Table 2). Non-steady-state models have been developed (Cuntz et al 2007, Shu et al 2008, Ferrio et al 2009) to better describe temporal and/or spatial variation in the isotopic composition of water within leaves that steady-state models do not address (Yakir et al 1990, Helliker and Ehleringer 2000, Sˇantru˚cˇek et al 2007). Indeed, non-steady-state models would have better predicted the diurnal variation in Dd l .…”

Section: Discussionmentioning

confidence: 99%

“…modeling results of Song et al (2011) who predicted leaf water of conifers should be less enriched in 18 O and thus the leaves would appear to have had lower temperatures due to non-steady-state behavior. Although our data add to the growing evidence of differences in leaf water enrichment between hardwoods and conifers, additional robust data sets will be required before it is possible to partition isotopic variation between non-steady-state behavior vs. differences in progressive enrichment of water with leaf length or distance from the leaf vein xylem (sensu Helliker and Ehleringer 2000, Gan et al 2002, Shu et al 2008.…”

Section: Leaf Water Isotopic Signals and Temperaturementioning

confidence: 99%

Reconstructing relative humidity from plant δ¹⁸O and δD as deuterium deviations from the global meteoric water line

Voelker

Brooks

Meinzer³

et al. 2014

Ecological Applications

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Cellulose delta18O and deltaD can provide insights on climates and hydrological cycling in the distant past and how these factors differ spatially. However, most studies of plant cellulose have used only one isotope, most commonly delta18O, resulting in difficulties partitioning variation in delta18O of precipitation vs. evaporative conditions that affect leaf water isotopic enrichment. Moreover, observations of pronounced diurnal differences from conventional steady-state model predictions of leaf water isotopic fractionation have cast some doubt on single isotope modeling approaches for separating precipitation and evaporation drivers of cellulose delta18O or deltaD. We explore a dual isotope approach akin to the concept of deuterium-excess (d), to establish deuterium deviations from the global meteoric water line in leaf water (deltad(l)) as driven by relative humidity (RH). To demonstrate this concept, we survey studies of leaf water delta18O and deltaD in hardwood vs. conifer trees. We then apply the concept to cellulose delta18O and deltaD using a mechanistic model of cellulose delta18O and deltaD to reconstruct deuterium deviations from the global meteoric water line (deltad(c)) in Quercus macrocarpa, Q. robur, and Pseudotsuga menziesii. For each species, deltad(c) showed strong correlations with RH across sites. deltad(c) agreed well with steady-state predictions for Q. macrocarpa, while for Q. robur, the relationship with RH was steeper than expected. The slope of deltad(c) vs. RH of P. menziesii was also close to steady-state predictions, but deltad(c) were more enriched than predicted. This is in agreement with our leaf water survey showing conifer deltad(l) was more enriched than predicted. Our data reveal that applications of this method should be appropriate for reconstructing RH from cellulose delta18O and deltaD after accounting for differences between hardwoods and conifers. Hence, deltad(c) should be useful for understanding variability in RH associated with past climatic cycles, across regional climates, or across complex terrain where climate modeling is challenging. Furthermore, deltad(c) and inferred RH values should help in constraining variation in source water delta18O.

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Isotopic studies of leaf water. Part 1: A physically based two-dimensional model for pine needles

Cited by 18 publications

References 49 publications

The nocturnal water cycle in an open‐canopy forest

The nocturnal water cycle in an open‐canopy forest

Effects of aridity and vegetation on plant-wax δD in modern lake sediments

Reconstructing relative humidity from plant δ¹⁸O and δD as deuterium deviations from the global meteoric water line

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Isotopic studies of leaf water. Part 1: A physically based two-dimensional model for pine needles

Cited by 18 publications

References 49 publications

The nocturnal water cycle in an open‐canopy forest

The nocturnal water cycle in an open‐canopy forest

Effects of aridity and vegetation on plant-wax δD in modern lake sediments

Reconstructing relative humidity from plant δ18O and δD as deuterium deviations from the global meteoric water line

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Reconstructing relative humidity from plant δ¹⁸O and δD as deuterium deviations from the global meteoric water line