Pooled versus separate measurements of tree-ring stable isotopes

Dorado‐Liñán, Isabel; Gutiérrez, Emília; Helle, Gerhard; Heinrich, Ingo; Andreu‐Hayles, Laia; Planells, Octavi; Leuenberger, Markus; Bürger, Carmen; Schleser, Gerhard H.

doi:10.1016/j.scitotenv.2011.02.010

Cited by 64 publications

(37 citation statements)

References 39 publications

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“…Most tree‐ring studies in natural environments have yielded results consistent with this strategy (Frank et al, ; Keller et al, ; Peñuelas et al, ; Saurer et al, ). However, there is also empirical support for plants following scenario (i) with constant c i (Dorado Liñán et al, ) or scenario (ii) where c i increases at the same rate as c a (McCarroll et al, ; Treydte et al, ). Other tree‐ring studies moreover have indicated intermediate situations between the constant c i and constant c i / c a scenarios, implying a more than expected increase in iWUE leaf , or between the constant c a – c i and constant c i / c a scenarios, associated with relatively moderate increase in iWUE leaf (Andreu‐Hayles et al, ; Lavergne et al, ; Leonardi et al, ; Urrutia‐Jalabert, Malhi, Barichivich, & Lara, ).…”

Section: Trends Reported In the Literature From Observationsmentioning

confidence: 99%

Observed and modelled historical trends in the water‐use efficiency of plants and ecosystems

Lavergne

Graven

Kauwe

et al. 2019

Global Change Biology

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Plant water‐use efficiency (WUE, the carbon gained through photosynthesis per unit of water lost through transpiration) is a tracer of the plant physiological controls on the exchange of water and carbon dioxide between terrestrial ecosystems and the atmosphere. At the leaf level, rising CO2 concentrations tend to increase carbon uptake (in the absence of other limitations) and to reduce stomatal conductance, both effects leading to an increase in leaf WUE. At the ecosystem level, indirect effects (e.g. increased leaf area index, soil water savings) may amplify or dampen the direct effect of CO2. Thus, the extent to which changes in leaf WUE translate to changes at the ecosystem scale remains unclear. The differences in the magnitude of increase in leaf versus ecosystem WUE as reported by several studies are much larger than would be expected with current understanding of tree physiology and scaling, indicating unresolved issues. Moreover, current vegetation models produce inconsistent and often unrealistic magnitudes and patterns of variability in leaf and ecosystem WUE, calling for a better assessment of the underlying approaches. Here, we review the causes of variations in observed and modelled historical trends in WUE over the continuum of scales from leaf to ecosystem, including methodological issues, with the aim of elucidating the reasons for discrepancies observed within and across spatial scales. We emphasize that even though physiological responses to changing environmental drivers should be interpreted differently depending on the observational scale, there are large uncertainties in each data set which are often underestimated. Assumptions made by the vegetation models about the main processes influencing WUE strongly impact the modelled historical trends. We provide recommendations for improving long‐term observation‐based estimates of WUE that will better inform the representation of WUE in vegetation models.

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Section: Trends Reported In the Literature From Observationsmentioning

confidence: 99%

Observed and modelled historical trends in the water‐use efficiency of plants and ecosystems

Lavergne

Graven

Kauwe

et al. 2019

Global Change Biology

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“…A cost-effective solution is to pool the wood from several trees prior to the chemistry and mass spectrometry (Borella et al, 1998;Dorada-Liñan, 2011;Lavergne et al, 2017;Leavitt, 2008;Liu et al, 2015;Szymczak et al, 2012). A cost-effective solution is to pool the wood from several trees prior to the chemistry and mass spectrometry (Borella et al, 1998;Dorada-Liñan, 2011;Lavergne et al, 2017;Leavitt, 2008;Liu et al, 2015;Szymczak et al, 2012).…”

Section: 1029/2019gb006195mentioning

confidence: 99%

“…Although there is clear potential for constructing long, well-replicated isotope chronologies using oak, this work can be constrained by the high cost of separating the alpha cellulose from individual latewood samples and measuring the samples individually by mass spectrometry. A cost-effective solution is to pool the wood from several trees prior to the chemistry and mass spectrometry (Borella et al, 1998;Dorada-Liñan, 2011;Lavergne et al, 2017;Leavitt, 2008;Liu et al, 2015;Szymczak et al, 2012). However, doubts have been raised about the wisdom of such an approach, as it has been argued that the isotope ratios from the rings of individual trees are influenced by tree age as well as by climate, and therefore require statistical detrending to remove these nonclimatic trends (Esper et al, 2010;Helama et al, 2015).…”

Section: 1029/2019gb006195mentioning

confidence: 99%

Absence of Age‐Related Trends in Stable Oxygen Isotope Ratios From Oak Tree Rings

Duffy

McCarroll

Loader

et al. 2019

Global Biogeochemical Cycles

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The potential for age‐related trends in the stable oxygen isotope ratios of latewood alpha cellulose was investigated in samples of living oak trees and historic building timbers from the UK. When the series are examined individually, it is clear that the strongest trends in individual trees and timbers reflect concurrent trends in climate. Nonclimatic trends are very small and represent random noise that can be removed by averaging. If the same data are analyzed using the more conventional approach of aligning the series by ring number and fitting a regression line, so that the magnitude of the age trend is based on the slope of the mean and the statistical significance on the correlation coefficient, the results are very different. We demonstrate that this conventional approach regularly produces spurious age trends with grossly inflated probabilities, because of offsets in the mean values of series of different length. We conclude that there is no need to detrend stable oxygen isotope series from individual trees or timbers of oak from the UK and that to do so would remove important climatic information. Long isotope chronologies can safely be constructed by combining data from multiple individual trees, or by pooling material from trees prior to chemical treatment and isotopic measurement. Age‐related trends may occur in other species or in other regions, but where they have been identified using the conventional “slope of the mean” approach they should be reassessed using the “mean of the slope” approach.

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“…The small ring size would have also created an unacceptably high risk of measurement error. Several recent studies have tested and proved that representativeness of pooled isotopic series for tree-ring carbon (d 13 C) compared to the individual isotopic series (Leavitt 2008;Liñán et al 2011;Liu et al 2012;Szymczak et al 2012;Woodley et al 2012). As the pooled mean will be within the mean obtained by averaging d 13 C values of individual trees, so that the ''error'' (probably more appropriately called ''the difference'') is negligible with respect to the error due to the preparation and analysis (Leavitt 2008).…”

Section: Stable Carbon Isotope Analysis and The Basic Equationsmentioning

confidence: 99%

Long-term variation of tree growth and intrinsic water-use efficiency in Schrenk spruce with increasing CO2 concentration and climate warming in the western Tianshan Mountains, China

Xiao-hong

Chen

et al. 2015

Acta Physiol Plant

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We combined dendrochronological methods and interannual d 13 C measurements to investigate radial growth and physiological responses of Schrenk spruce (Picea schrenkiana) in response to rising atmospheric CO 2 concentration (C a ) and changing climate in high-elevation forests in China's western Tianshan Mountains. The mean maximum temperature in May to August, reconstructed from d 13 C, revealed an overall warming trend, with persistent warm periods from 1910 to 1920, and from 1970 to 1980. Intrinsic water use efficiency (iWUE) increased by 28 % over the last 160 years; temporal trends in iWUE were calculated under three theoretical scenarios as a baseline for interpreting the observed gas-exchange at increasing C a . Basal area increment (BAI) increased by 51.4 % since 1850 with two apparent increases and decreases. Trees exhibited sharp declines in BAI along with enhanced iWUE during the warmer periods; this was possibly due to a reduced stomatal conductance which prevented excessive water loss from trees. Conversely, BAI increased at reduced iWUE (-3.6 %, -7.4 %) during two cold-wet periods (e.g., 1880 to 1992, and 1945 to 1960), suggesting that a diminished water stress caused the observed growth pattern. However, BAI increased significantly (49.4 %) from 1965 to 1983 with constant intercellular atmospheric CO 2 concentrations (C i ) response scenario under acute water limitations, indicating the CO 2 stimulation of tree growth. These results showed that even at high elevations, increased iWUE may not lead to longterm enhancement of tree growth, and other factors may counteract CO 2 -fertilization effects, especially those related to a warming-induced drought. The results of this study suggest that the current models may overestimate the sink capacity of temperate forests, and indicate that multi-proxy records are needed to disentangle the role of a limiting factor in modulating the response of the Schrenk spruce forest to current climate change scenarios.

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Pooled versus separate measurements of tree-ring stable isotopes

Cited by 64 publications

References 39 publications

Observed and modelled historical trends in the water‐use efficiency of plants and ecosystems

Observed and modelled historical trends in the water‐use efficiency of plants and ecosystems

Absence of Age‐Related Trends in Stable Oxygen Isotope Ratios From Oak Tree Rings

Long-term variation of tree growth and intrinsic water-use efficiency in Schrenk spruce with increasing CO2 concentration and climate warming in the western Tianshan Mountains, China

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