Radiocarbon Wiggle Matching on Laminated Sediments Delivers High-Precision Chronologies

Rey, Fabian; Gobet, Erika; Szidat, Sönke; Lotter, André F.; Gilli, Adrian; Hafner, Albert; Tinner, Willy

doi:10.1017/rdc.2018.47

Cited by 21 publications

(30 citation statements)

References 58 publications

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“…, Rey et al. ), we mostly selected short‐lived and delicate plant organs (e.g., leaves, flowers, twigs, see Appendix : Table S1). Radiocarbon dates were converted to calendar years before present (i.e., before 1950 CE [Common Era], cal.…”

Section: Methodsmentioning

confidence: 99%

Unprecedented herbivory threatens rear‐edge populations of Betula in southwestern Eurasia

Morales‐Molino

Tinner

Perea

et al. 2019

Ecology

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Mediterranean rear‐edge populations of Betula, located at the southwestern Eurasian margin of the distribution range, represent unique reservoirs of genetic diversity. However, increasing densities of wild ungulates, enhanced dryness, and wildfires threaten their future persistence. A historical perspective on the past responses of these relict populations to changing herbivory, fire occurrence and climatic conditions may contribute to assessing their future responses under comparable scenarios. We have reconstructed vegetation and disturbance (grazing, fire) history in the Cabañeros National Park (central‐southern Spain) using the paleoecological records of two small mires. We particularly focused on the historical range of variation in disturbance regimes, and the dynamics of rear‐edge Betula populations and herbivore densities. Changes in water availability, probably related to the North Atlantic Oscillation (NAO) index, and land‐use history have played a crucial role in vegetation shifts. Our data suggest that heathlands (mainly Erica arborea and E. scoparia) and Quercus woodlands dominated during dry phases while Sphagnum bogs and Betula stands expanded during wet periods. Betula populations survived past moderately dry periods but were unable to cope with enhanced land use, particularly increasing livestock raising since ~1,100–900 cal. yr BP (850–1,050 CE), and eventually underwent local extinction. High herbivore densities not only contributed to the Betula demise but also caused the retreat of Sphagnum bogs. Ungulate densities further rose at ~200–100 cal. yr BP (1750–1850 CE) associated with the historically documented intensification of land use around the Ecclesiastical Confiscation. However, herbivory reached truly unprecedented values only during the last decades, following rural depopulation and subsequent promotion of big game hunting. For the first time in temperate and Mediterranean Europe, we have used the abundances of fossil dung fungal spores to assess quantitatively that current high herbivore densities exceed the historical range of variation. In contrast, present fire activity lies within the range of variation of the last millennia, with fires (mainly human‐set) mostly occurring during dry periods. Our paleodata highlight the need of controlling the densities of wild ungulates to preserve ecosystem composition and functioning. We also urge to restore Betula populations in suitable habitats where they mostly disappeared because of excessive human activities.

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Section: Methodsmentioning

confidence: 99%

Unprecedented herbivory threatens rear‐edge populations of Betula in southwestern Eurasia

Morales‐Molino

Tinner

Perea

et al. 2019

Ecology

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“…The varve counts and all 14 C ages were incorporated into an OxCal V sequence in an approach similar to that used by Rey et al (2019). The V sequence differs from the P sequence in that it does not model sediment deposition.…”

Section: Age-depth Modelingmentioning

confidence: 99%

“…Recent advances have reduced the required sample mass for AMS 14 C analysis, opening new opportunities for researchers (Delqué-Količ et al, 2013;Freeman et al, 2016;Santos et al, 2007;Shah Walter et al, 2015). The recently developed MIni CArbon DAting System (MICADAS) has the capability to analyze samples with miniature masses via the input of samples in a gaseous form, thus omitting sample graphitization (Ruff et al, 2007(Ruff et al, , 2010a(Ruff et al, , 2010bSzidat et al, 2014;Wacker et al, 2010aWacker et al, , b, 2013. Samples containing as little as a few micrograms of C can be dated using the gas-source input of the MICADAS.…”

Section: Introductionmentioning

confidence: 99%

Miniature radiocarbon measurements ( < 150 µg C) from sediments of Lake Żabińskie, Poland: effect of precision and dating density on age–depth models

et al. 2020

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Abstract. The recent development of the MIni CArbon DAting System (MICADAS) allows researchers to obtain radiocarbon (14C) ages from a variety of samples with miniature amounts of carbon (<150 µg C) by using a gas ion source input that bypasses the graphitization step used for conventional 14C dating with accelerator mass spectrometry (AMS). The ability to measure smaller samples, at reduced cost compared with graphitized samples, allows for greater dating density of sediments with low macrofossil concentrations. In this study, we use a section of varved sediments from Lake Żabińskie, NE Poland, as a case study to assess the usefulness of miniature samples from terrestrial plant macrofossils for dating lake sediments. Radiocarbon samples analyzed using gas-source techniques were measured from the same depths as larger graphitized samples to compare the reliability and precision of the two techniques directly. We find that the analytical precision of gas-source measurements decreases as sample mass decreases but is comparable with graphitized samples of a similar size (approximately 150 µg C). For samples larger than 40 µg C and younger than 6000 BP, the uncalibrated 1σ age uncertainty is consistently less than 150 years (±0.010 F14C). The reliability of 14C ages from both techniques is assessed via comparison with a best-age estimate for the sediment sequence, which is the result of an OxCal V sequence that integrates varve counts with 14C ages. No bias is evident in the ages produced by either gas-source input or graphitization. None of the 14C ages in our dataset are clear outliers; the 95 % confidence intervals of all 48 calibrated 14C ages overlap with the median best-age estimate. The effects of sample mass (which defines the expected analytical age uncertainty) and dating density on age–depth models are evaluated via simulated sets of 14C ages that are used as inputs for OxCal P-sequence age–depth models. Nine different sampling scenarios were simulated in which the mass of 14C samples and the number of samples were manipulated. The simulated age–depth models suggest that the lower analytical precision associated with miniature samples can be compensated for by increased dating density. The data presented in this paper can improve sampling strategies and can inform expectations of age uncertainty from miniature radiocarbon samples as well as age–depth model outcomes for lacustrine sediments.

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“…The varve counts and all 14 C ages were incorporated into an OxCal V-sequence in an approach similar to that used by Rey et al (2019). We input the number of varves in 10 cm intervals to the V-sequence as an age 'Gap' with associated uncertainty.…”

Section: Age-depth Modelingmentioning

confidence: 99%

“…Extremely precise age estimates were also produced using this method for Moossee, Switzerland by Rey et al (2019). A combination of varve counts and C ages from the Moossee sediments generated a V-sequence output with a mean 95% CI of 38 years.…”

Section: The Oxcal V-sequence Best-age Estimatementioning

confidence: 99%

Miniature radiocarbon measurements (

Zander¹,

Szidat²,

Kaufman³

et al. 2019

Preprint

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Abstract. The recent development of the MIni CArbon DAting System (MICADAS) allows researchers to obtain radiocarbon (14C) ages from a variety of samples with miniature amounts of carbon (<&#8201;150&#8201;&#956;g&#8201;C) by using a gas ion source input that bypasses the graphitization step used for conventional 14C dating with accelerator mass spectrometry (AMS). The ability to measure smaller samples, at reduced cost compared with graphitized samples, allows for greater dating density of sediments with low macrofossil concentrations. In this study, we use a section of varved sediments from Lake &#379;abi&#324;skie, NE Poland, as a case study to assess the usefulness of miniature samples from terrestrial plant macrofossils for dating lake sediments. Radiocarbon samples analyzed using gas-source techniques were measured from the same depths as larger graphitized samples to compare the reliability and precision of the two techniques directly. We find that the analytical precision of gas-source measurements decreases as sample mass decreases, but is comparable with graphitized samples of a similar size (approximately 150&#8201;&#956;g&#8201;C). The age uncertainty is consistently less than 150 years (uncalibrated 1&#963;) for samples larger than 40&#8201;&#956;g&#8201;C. The reliability of 14C ages from both techniques is assessed via comparison with a best-age estimate for the sediment sequence, which is the result of an OxCal V-sequence that integrates varve counts with 14C ages. No bias is evident in the ages produced by either gas-source input or graphitization. None of the 14C ages in our dataset are clear outliers; the 95&#8201;% confidence intervals of all 48 calibrated 14C ages overlap with the median best-age estimate. The effects of sample mass (which defines the expected analytical age uncertainty) and dating density on age-depth models are evaluated via simulated sets of 14C ages that are used as inputs for OxCal P-sequence age-depth models. Nine different sampling scenarios were simulated in which the mass of 14C samples and the number of samples were manipulated. The simulated age-depth model results suggest that the lower analytical precision associated with miniature samples can be compensated for by increased dating density. The data presented in this paper can improve sampling strategies and can inform expectations of age uncertainty from miniature radiocarbon samples as well as age-depth model outcomes for lacustrine sediments.

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Radiocarbon Wiggle Matching on Laminated Sediments Delivers High-Precision Chronologies

Cited by 21 publications

References 58 publications

Unprecedented herbivory threatens rear‐edge populations of Betula in southwestern Eurasia

Unprecedented herbivory threatens rear‐edge populations of Betula in southwestern Eurasia

Miniature radiocarbon measurements ( < 150 µg C) from sediments of Lake Żabińskie, Poland: effect of precision and dating density on age–depth models

Miniature radiocarbon measurements (

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Radiocarbon Wiggle Matching on Laminated Sediments Delivers High-Precision Chronologies

Cited by 21 publications

References 58 publications

Unprecedented herbivory threatens rear‐edge populations of Betula in southwestern Eurasia

Unprecedented herbivory threatens rear‐edge populations of Betula in southwestern Eurasia

Miniature radiocarbon measurements ( &lt; 150 µg C) from sediments of Lake Żabińskie, Poland: effect of precision and dating density on age–depth models

Miniature radiocarbon measurements (

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Miniature radiocarbon measurements ( < 150 µg C) from sediments of Lake Żabińskie, Poland: effect of precision and dating density on age–depth models