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Dolores R Piperno - One of the best experts on this subject based on the ideXlab platform.
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Phytolith radiocarbon dating in archaeological and paleoecological research a case study of Phytoliths from modern neotropical plants and a review of the previous dating evidence
Journal of Archaeological Science, 2016Co-Authors: Dolores R PipernoAbstract:Abstract Recent carbon-14 studies of Phytoliths from modern plants collected from extra-tropical regions of the world have yielded dates that are too old by several hundred to thousands of years. These findings have prompted questions about the suitability of Phytolith-derived carbon for dating in archaeological and paleo-environmental research. In this paper, Phytolith 14 C ages are determined from a number of modern Neotropical plant taxa collected between 1964 and 2013. The specimens studied are maize ( Zea mays L.), two squash species ( Cucurbita ecuadorensis H.C.Cutler & Whitaker and C. ficifolia Bouche), and two trees common in Neotropical forest, Hirtella americana L. and Socratea durissima (Oersted) H. Uendl. They represent families, genera, and species that are well-represented in Neotropical archaeological and paleoecological sediments. Every Phytolith sample returned a post-bomb 14 C Phytolith age reflecting collection after 1955, with the exception of a herbarium specimen that was treated with chemicals containing radiocarbon-dead carbon. The Phytolith dates do not indicate a source of extraneous old or young carbon occurring on the surfaces or inside of Phytoliths that bias their ages. Such findings are also reflected by previous Phytolith 14 C studies of ancient Neotropical sites. Possible reasons for the differences in results between these and other studies and varying interpretations of soil and sediment Phytolith 14 C analyses by different investigators are discussed.
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Phytoliths a comprehensive guide for archaeologists and paleoecologists
2006Co-Authors: Dolores R PipernoAbstract:1 The Production, Deposition, and Dissolution of Phytoliths 2 Phytolith Morphology 3 Phytoliths in Domesticated Plants and Their Wild Ancestors 4 Field Techniques and Research Design 5 Laboratory Techniques 6 The Interpretation of Phytolith Assemblages: Method and Theory 7 The Role of Phytoliths in Archaeological Reconstruction 8 The Role of Phytoliths in Paleoecology
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evidence for the control of Phytolith formation in cucurbita fruits by the hard rind hr genetic locus archaeological and ecological implications
Proceedings of the National Academy of Sciences of the United States of America, 2002Co-Authors: Dolores R Piperno, Irene Holst, Linda Wesselbeaver, Thomas C AndresAbstract:Many angiosperms, both monocotyledons and dicotyledons, heavily impregnate their vegetative and reproductive organs with solid particles of silicon dioxide (SiO2) known as opaline Phytoliths. The underlying mechanisms accounting for the formation of Phytoliths in plants are poorly understood, however. Using wild and domesticated species in the genus Cucurbita along with their F1 and F2 progeny, we have demonstrated that the production of large diagnostic Phytoliths in fruit rinds exhibits a one-to-one correspondence to the lignification of these structures. We propose that Phytolith formation in Cucurbita fruits is primarily determined by a dominant genetic locus, called hard rind (Hr), previously shown to code for lignin deposition. If true, this evidence represents a demonstration of genetic control over Phytolith production in a dicotyledon and provides considerable support to hypotheses that silica Phytoliths constitute another important system of mechanical defense in plants. Our research also identifies Hr as another single locus controlling more than one important phenotypic difference between wild and domesticated plants, and establishes rind tissue cell structure and hardness under the effects of Hr as an important determinant of Phytolith morphology. When recovered from pre-Columbian archaeological sites, Cucurbita Phytoliths represent genetically controlled fossil markers of exploitation and domestication in this important economic genus.
Elizabeth A Webb - One of the best experts on this subject based on the ideXlab platform.
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effects of leaf length and development stage on the triple oxygen isotope signature of grass leaf water and Phytoliths insights for a proxy of continental atmospheric humidity
Biogeosciences, 2019Co-Authors: Elizabeth A WebbAbstract:Abstract. Continental relative humidity (RH) is a key climate parameter, but there is a lack of quantitative RH proxies suitable for climate model–data comparisons. Recently, a combination of climate chamber and natural transect calibrations have laid the groundwork for examining the robustness of the triple oxygen isotope composition ( δ′18 O and 17 O-excess) of Phytoliths, that can preserve in sediments, as a new proxy for past changes in RH. However, it was recommended that besides RH, additional factors that may impact δ′18 O and 17 O-excess of plant water and Phytoliths be examined. Here, the effects of grass leaf length, leaf development stage and day–night alternations are addressed from growth chamber experiments. The triple oxygen isotope compositions of leaf water and Phytoliths of the grass species F. arundinacea are analysed. Evolution of the leaf water δ′18 O and 17 O-excess along the leaf length can be modelled using a string-of-lakes approach to which an unevaporated–evaporated mixing equation must be added. We show that for Phytoliths to record this evolution, a kinetic fractionation between leaf water and silica, increasing from the base to the apex, must be assumed. Despite the isotope heterogeneity of leaf water along the leaf length, the bulk leaf Phytolith δ′18 O and 17 O-excess values can be estimated from the Craig and Gordon model and a mean leaf water–Phytolith fractionation exponent ( λPhyto-LW) of 0.521. In addition to not being leaf length dependent, δ′18 O and 17 O-excess of grass Phytoliths are expected to be impacted only very slightly by the stem vs. leaf biomass ratio. Our experiment additionally shows that because a lot of silica polymerises in grasses when the leaf reaches senescence (58 % of leaf Phytoliths in mass), RH prevailing during the start of senescence should be considered in addition to RH prevailing during leaf growth when interpreting the 17 O-excess of grass bulk Phytoliths. Although under the study conditions 17 O-excess Phyto do not vary significantly from constant day to day–night conditions, additional monitoring at low RH conditions should be done before drawing any generalisable conclusions. Overall, this study strengthens the reliability of the 17 O-excess of Phytoliths to be used as a proxy of RH. If future studies show that the mean value of 0.521 used for the grass leaf water–Phytolith fractionation exponent λPhyto-LW is not climate dependent, then grassland leaf water 17 O-excess obtained from grassland Phytolith 17 O-excess would inform on isotope signals of several soil–plant-atmosphere processes.
Frederic Prie - One of the best experts on this subject based on the ideXlab platform.
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Effects of leaf length and development stage on the triple oxygen isotope signature of grass leaf water and Phytoliths: insights for a proxy of continental atmospheric humidity
Biogeosciences, 2019Co-Authors: Elizabeth Webb, Clément Piel, Corinne Sonzogni, Jean-charles Mazur,, Monique Pierre, Frederic PrieAbstract:Continental relative humidity (RH) is a key climate parameter, but there is a lack of quantitative RH proxies suitable for climate model-data comparisons. Recently, a combination of climate chamber and natural transect calibrations have laid the groundwork for examining the robustness of the triple oxygen isotope composition (delta O-'18 and O-17-excess) of Phytoliths, that can preserve in sediments, as a new proxy for past changes in RH. However, it was recommended that besides RH, additional factors that may impact delta'O-18 and O-17-excess of plant water and Phytoliths be examined. Here, the effects of grass leaf length, leaf development stage and day-night alternations are addressed from growth chamber experiments. The triple oxygen isotope compositions of leaf water and Phytoliths of the grass species F. arundinacea are analysed. Evolution of the leaf water delta'O-18 and O-17-excess along the leaf length can be modelled using a string-of-lakes approach to which an unevaporated-evaporated mixing equation must be added. We show that for Phytoliths to record this evolution, a kinetic fractionation between leaf water and silica, increasing from the base to the apex, must be assumed. Despite the isotope heterogeneity of leaf water along the leaf length, the bulk leaf Phytolith delta'O-18 and O-17-excess values can be estimated from the Craig and Gordon model and a mean leaf water-Phytolith fractionation exponent (lambda(Phyto-LW)) of 0.521. In addition to not being leaf length dependent, delta'O-18 and O-17-excess of grass Phytoliths are expected to be impacted only very slightly by the stem vs. leaf biomass ratio. Our experiment additionally shows that because a lot of silica polymerises in grasses when the leaf reaches senescence (58 % of leaf Phytoliths in mass), RH prevailing during the start of senescence should be considered in addition to RH prevailing during leaf growth when interpreting the O-17-excess of grass bulk Phytoliths. Although under the study conditions O-17-excess(Phyto) do not vary significantly from constant day to day-night conditions, additional monitoring at low RH conditions should be done before drawing any generalisable conclusions. Overall, this study strengthens the reliability of the O-17-excess of Phytoliths to be used as a proxy of RH. If future studies show that the mean value of 0.521 used for the grass leaf water-Phytolith fractionation exponent lambda(Phyto-LW) is not climate dependent, then grassland leaf water O-17-excess obtained from grassland Phytolith O-17-excess would inform on isotope signals of several soil-plant-atmosphere processes.
Changsui Wang - One of the best experts on this subject based on the ideXlab platform.
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point count estimation of articulated husk Phytoliths of foxtail millet and its prospective use in agricultural archaeology
Quaternary International, 2016Co-Authors: Xue Shang, Xin Wang, Pengfei Sheng, Changsui WangAbstract:Abstract Many researchers have focused on the precise identification of Phytoliths extracted from archaeological samples, and on the extraction methods of Phytolith from all kinds of samples as well. Additionally, it is important to perfect the scientific method of Phytolith quantification. Phytoliths, especially from the husk, are easily broken after being long-buried or during extraction treatment. These can result in uncertainties about quantification of grain numbers and varies under different conditions. Here we introduce a method of point count estimation of articulated millet husk Phytoliths, and evaluate its accuracy. As a result, we successfully used the point count method into estimating the area of husk Phytolith in unit weight of modern millet samples, which will broaden the available data in archaeobiological research. We suggest precise estimations can therefore be done with this method.
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comparison of dry ashing and wet oxidation methods for recovering articulated husk Phytoliths of foxtail millet and common millet from archaeological soil
Journal of Archaeological Science, 2014Co-Authors: Xin Wang, Hongen Jiang, Xue Shang, Weilin Wang, Yan Wu, Pengcheng Zhang, Changsui WangAbstract:Phytolith research on foxtail and common millets represent one of the keys to explore early agricultural activities in the Yellow River basin in China. However, the Phytoliths of these two millets easily disintegrate during burial and the extraction process. In this paper, both dry ashing and wet oxidation methods were applied to determine the effects on Phytolith extraction from archaeological soil samples. The results indicated that the dry ashing method had two significant advantages over wet oxidation: (1) the morphology of husk Phytoliths was retained to a greater extent; and (2) nearly all the charcoalified tissues were removed successfully. The dry ashing method proved to be a better method for Phytolith extraction of both foxtail millet as well as common millet from archaeological samples. (C) 2014 Elsevier Ltd. All rights reserved.
Elizabeth Webb - One of the best experts on this subject based on the ideXlab platform.
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Effects of leaf length and development stage on the triple oxygen isotope signature of grass leaf water and Phytoliths: insights for a proxy of continental atmospheric humidity
Biogeosciences, 2019Co-Authors: Elizabeth Webb, Clément Piel, Corinne Sonzogni, Jean-charles Mazur,, Monique Pierre, Frederic PrieAbstract:Continental relative humidity (RH) is a key climate parameter, but there is a lack of quantitative RH proxies suitable for climate model-data comparisons. Recently, a combination of climate chamber and natural transect calibrations have laid the groundwork for examining the robustness of the triple oxygen isotope composition (delta O-'18 and O-17-excess) of Phytoliths, that can preserve in sediments, as a new proxy for past changes in RH. However, it was recommended that besides RH, additional factors that may impact delta'O-18 and O-17-excess of plant water and Phytoliths be examined. Here, the effects of grass leaf length, leaf development stage and day-night alternations are addressed from growth chamber experiments. The triple oxygen isotope compositions of leaf water and Phytoliths of the grass species F. arundinacea are analysed. Evolution of the leaf water delta'O-18 and O-17-excess along the leaf length can be modelled using a string-of-lakes approach to which an unevaporated-evaporated mixing equation must be added. We show that for Phytoliths to record this evolution, a kinetic fractionation between leaf water and silica, increasing from the base to the apex, must be assumed. Despite the isotope heterogeneity of leaf water along the leaf length, the bulk leaf Phytolith delta'O-18 and O-17-excess values can be estimated from the Craig and Gordon model and a mean leaf water-Phytolith fractionation exponent (lambda(Phyto-LW)) of 0.521. In addition to not being leaf length dependent, delta'O-18 and O-17-excess of grass Phytoliths are expected to be impacted only very slightly by the stem vs. leaf biomass ratio. Our experiment additionally shows that because a lot of silica polymerises in grasses when the leaf reaches senescence (58 % of leaf Phytoliths in mass), RH prevailing during the start of senescence should be considered in addition to RH prevailing during leaf growth when interpreting the O-17-excess of grass bulk Phytoliths. Although under the study conditions O-17-excess(Phyto) do not vary significantly from constant day to day-night conditions, additional monitoring at low RH conditions should be done before drawing any generalisable conclusions. Overall, this study strengthens the reliability of the O-17-excess of Phytoliths to be used as a proxy of RH. If future studies show that the mean value of 0.521 used for the grass leaf water-Phytolith fractionation exponent lambda(Phyto-LW) is not climate dependent, then grassland leaf water O-17-excess obtained from grassland Phytolith O-17-excess would inform on isotope signals of several soil-plant-atmosphere processes.