Effect of Changes in Leaf Water Oxygen Isotopic Composition on Discrimination Against C18O16O During Photosynthetic Gas Exchange

Flanagan, LB; Phillips, SL; Ehleringer, JR; Lloyd, Jon; Farquhar, Graham D.

doi:10.1071/pp9940221

Cited by 60 publications

(81 citation statements)

References 38 publications

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“…This positive correlation with transpiration rate is wiped out upon normalization against ⌬ C , as shown in Figure 8. Nonetheless, a positive trend of 1 Ϫ ⌬ lw,bulk ⌬ C with E, consistent with the Péclet model, has been reported (Walker et al, 1989;Flanagan et al, 1994;Barbour et al, 2000). All of the studies mentioned made direct isotopic measurements of extracted leaf water except for that of Barbour and co-workers (2000).…”

Section: Lower Enrichment Of Bulk Leaf Water Arising From Péclet Effectsupporting

confidence: 63%

“…Although the Craig-Gordon model basically describes water enrichment at the sites of evaporation compared with locally transpired water, it cannot adequately account for other aspects of leaf water enrichment, particularly the spatial variation of leaf water 18 O and/or D contents (Luo and Sternberg, 1992; Bariac et al, 1994;Wang and Yakir, 1995;Helliker and Ehleringer, 2000). Also, the Craig-Gordon model has often been found to overestimate the isotopic enrichment of bulk leaf water (Allison et al, 1985; Bariac et al, 1989;Walker et al, 1989;Walker and Brunel, 1990;Yakir et al, 1990;Flanagan et al, 1991aFlanagan et al, , 1991bFlanagan et al, , 1994Wang et al, 1998). To explain such observations, several other models have been suggested in conjunction with the Craig-Gordon model, namely the two-pool model (Leaney et al, 1985), the Péclet model , and the string-of-lakes model (Gat and Bowser, 1991).…”

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confidence: 99%

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18O Spatial Patterns of Vein Xylem Water, Leaf Water, and Dry Matter in Cotton Leaves

et al. 2002

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Three leaf water models (two-pool model, Péclet effect, and string-of-lakes) were assessed for their robustness in predicting leaf water enrichment and its spatial heterogeneity. This was achieved by studying the 18 O spatial patterns of vein xylem water, leaf water, and dry matter in cotton (Gossypium hirsutum) leaves grown at different humidities using new experimental approaches. Vein xylem water was collected from intact transpiring cotton leaves by pressurizing the roots in a pressure chamber, whereas the isotopic content of leaf water was determined without extracting it from fresh leaves with the aid of a purpose-designed leaf punch. Our results indicate that veins have a significant degree of lateral exchange with highly enriched leaf water. Vein xylem water is thus slightly, but progressively enriched in the direction of water flow. Leaf water enrichment is dependent on the relative distances from major veins, with water from the marginal and intercostal regions more enriched and that next to veins and near the leaf base more depleted than the Craig-Gordon modeled enrichment of water at the sites of evaporation. The spatial pattern of leaf water enrichment varies with humidity, as expected from the string-of-lakes model. This pattern is also reflected in leaf dry matter. All three models are realistic, but none could fully account for all of the facets of leaf water enrichment. Our findings acknowledge the presence of capacitance in the ground tissues of vein ribs and highlight the essential need to incorporate Péclet effects into the string-of-lakes model when applying it to leaves.The isotopic composition of leaf water reflects local humidity, and its imprints on plant cellulose and other fossil materials have been widely explored for palaeoclimatic reconstruction. To date, isotopic values of wood cellulose (Epstein et al., 1977;Yapp and Epstein, 1982;Edwards et al., 1985;Edwards and Fritz, 1986;Roden et al., 2000), grassland phytoliths (Webb and Longstaffe, 2000), and deer bone (Cormie et al., 1994) have been shown to be related to leaf water isotopic composition. Leaf water isotopic signature is not only imprinted on plant organic matter but is also recorded in atmospheric CO 2 and O 2 . The CO 2 interacts and undergoes isotopic exchange with leaf water, and O 2 is released by the plant during photosynthesis. Changes in the oxygen isotope ratios of CO 2 and O 2 can thus be used to study variations in the net exchange of CO 2 in terrestrial ecosystems and in the balance of terrestrial and marine productivity (Bender et al., 1985;Bender et al., 1994). Because all of these applications critically depend on estimation of the leaf water oxygen isotopic ratio, a good understanding of the nature of leaf water enrichment is needed.The isotopic composition of leaf water is most commonly estimated from the model of a freely evaporating water surface (Craig and Gordon, 1965) where isotopic fractionation is driven by the lower vapor pressure and diffusivity of the heavier molecules. Although the Craig-Gordon m...

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Section: Lower Enrichment Of Bulk Leaf Water Arising From Péclet Effectsupporting

confidence: 63%

mentioning

confidence: 99%

18O Spatial Patterns of Vein Xylem Water, Leaf Water, and Dry Matter in Cotton Leaves

et al. 2002

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“…1974). However, these models tend to overestimate the heavy isotope enrichment of evaporated leaf water, an offset that increases with increasing transpiration (Barnes & Walker 1989;Flanagan et al . 1994).…”

Section: Stable Isotopes In Leaf Water Of Conifersmentioning

confidence: 99%

Needle cell elongation and maturation timing derived from pine needle cellulose δ¹⁸O

Wright

Leavitt

2005

Plant Cell & Environment

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“…The remaining two-thirds diffuse back to the atmosphere after dissolving and isotopically equilibrating with chloroplast water. The retrodiffused CO2 is enriched in 180 relative to the soil water that feeds the plant because of evaporative enrichment of leaf water [Flanagan et al, 1994;Yakir et al, 1994]. …”

Section: The Leaf Component Co2 Diffusing Into Leaves Duringmentioning

confidence: 99%

Measurement of ¹⁸O/¹⁶O in the soil‐atmosphere CO₂ flux

Miller¹,

Yakir²,

White³

et al. 1999

Global Biogeochemical Cycles

111

218

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We demonstrate that during measurements "invasion" of atmospheric CO2 (the diffusion of ambient CO2 into the soil, followed by partial equilibration and retrodiffusion) must be considered to accurately calculate the 180 of the soil-respired CO2. The impact of invasion in natural settings is also considered. We also have determined the effective kinetic fractionation of CO2 diffusion out of the soil to be 7.2 +_ 0.3%0. High-resolution (1 cm) depth profiles of 18 0 of near-surface (top 10 cm) soil CO2 were carried out by gas chromatography--isotope ratio mass spectrometry (GC-IRMS). This novel technique allowed us to observe the competitive diffusion-equilibration process near the soil surface and to test simulations by a diffusion and equilibration model of the soil CO2 18 0 content.

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Effect of Changes in Leaf Water Oxygen Isotopic Composition on Discrimination Against C18O16O During Photosynthetic Gas Exchange

Cited by 60 publications

References 38 publications

18O Spatial Patterns of Vein Xylem Water, Leaf Water, and Dry Matter in Cotton Leaves

18O Spatial Patterns of Vein Xylem Water, Leaf Water, and Dry Matter in Cotton Leaves

Needle cell elongation and maturation timing derived from pine needle cellulose δ¹⁸O

Measurement of ¹⁸O/¹⁶O in the soil‐atmosphere CO₂ flux

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Effect of Changes in Leaf Water Oxygen Isotopic Composition on Discrimination Against C18O16O During Photosynthetic Gas Exchange

Cited by 60 publications

References 38 publications

18O Spatial Patterns of Vein Xylem Water, Leaf Water, and Dry Matter in Cotton Leaves

18O Spatial Patterns of Vein Xylem Water, Leaf Water, and Dry Matter in Cotton Leaves

Needle cell elongation and maturation timing derived from pine needle cellulose δ18O

Measurement of 18O/16O in the soil‐atmosphere CO2 flux

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Product

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Needle cell elongation and maturation timing derived from pine needle cellulose δ¹⁸O

Measurement of ¹⁸O/¹⁶O in the soil‐atmosphere CO₂ flux